WorldWideScience

Sample records for scatter photocoagulation treatment

  1. Laser photocoagulation - eye

    Science.gov (United States)

    Laser coagulation; Laser eye surgery; Photocoagulation; Laser photocoagulation - diabetic eye disease; Laser photocoagulation - diabetic retinopathy; Focal photocoagulation; Scatter (or pan retinal) photocoagulation; Proliferative ...

  2. Green laser photocoagulator for the treatment of diabetic retinopathy ...

    Indian Academy of Sciences (India)

    An all-solid-state green laser photocoagulator at 532 nm with output power varying from 100 mW to 1 W in a step of 10 mW and exposure time varying from 50 ms to 1000 ms in a step of 10 ms is developed for the treatment of diabetic retinopathy. The output power stability is better than ± 1.5% with a nearly diffraction-limited ...

  3. Photocoagulation treatment for clinically significant radiation macular oedema

    Energy Technology Data Exchange (ETDEWEB)

    Kinyoun, J.L.; Zamber, R.W.; Lawrence, B.S.; Barlow, W.E.; Arnold, A.M. [Washington Univ., Seattle, WA (United States)

    1995-02-01

    Macular oedema is a leading cause of vision loss in patients with radiation retinopathy. In an effort to find an effective treatment for this vision threatening complication, 12 eyes (eight patients) were treated with photocoagulation for clinically significant radiation macular oedema (CSRMO) defined as central macular thickening, exudates threatening the macular centre, or one disc area of thickening in the macula. Median visual acuity improved from 20/100 pre-operatively to 20/90 at the initial post-operative examination (mean follow up 5 months) and to 20/75 at the final post-operative examination (mean follow up 39 months). At the final post-operative examination, visual acuity had improved in eight (67%) eyes and six (50%) eyes had complete resolution of the CSRMO; two (17%) other eyes had improved anatomically in that fewer CSRMO criteria were present. These results suggest that macular photocoagulation is effective in decreasing macular oedema and improving vision in eyes with CSRMO. (author).

  4. Clinical research of retinal laser photocoagulation and Ranibizumab on the treatment of neovascular glaucoma

    Directory of Open Access Journals (Sweden)

    Wei-Peng Jiang

    2015-10-01

    Full Text Available AIM: To explore the improvement of visual function and the adverse reactions of retinal laser photocoagulation combined with ranibizumab for the treatment of neovascular glaucoma(NVG, to provide the basis for clinical treatment.METHODS: One hundred patients with 129 eyes in our hospital from January 2012 to June 2014 were selected. They were randomly divided into the observation group and the control group, 50 cases in each one. Patients in the control group(67 eyeswere treated with retinal laser photocoagulation, and those in the observation group(62 eyeswere given retinal laser photocoagulation combined with ranibizumab treatment. After the treatment, the degeneration of iris neovascularization, visual acuity, intraocular pressure, ocular fundus and the adverse reactions were evaluated. Optical coherence tomography(OCTwas used to detect retinal nerve fiber layer(RNFLthickness and visual field defect. RESULTS: The degeneration rate of the iris neovascularization in the observation group was 95.2%(59/62, higher than that of the control group 83.6%(56/67(PPPPPP>0.05.CONCLUSION: The treatment of NVG with laser photocoagulation combined with ranibizumab has good clinical efficacy, and can significantly improve the vision and retinal structure and function of the patients, and is safer.

  5. The potential neuroprotective effects of weekly treatment with glatiramer acetate in diabetic patients after panretinal photocoagulation

    Directory of Open Access Journals (Sweden)

    Mitne S

    2011-07-01

    Full Text Available Somaia Mitne1,2, Sergio Henrique Teixeira1, Michal Schwartz3, Michael Belkin4, Michel Eid Farah1, Nilva S Bueno de Moraes1, Luciana da Cruz Nóia1, Ângela Tavares Paes2, Cláudio Luiz Lottenberg2, Augusto Paranhos Júnior1,21Department of Ophthalmology, Federal University of São Paulo, 2Instituto Israelita de Ensino e Pesquisa Albert Einstein, HIAE, São Paulo, Brazil; 3Department of Neurobiology, The Weizmann Institute of Science, Rehovot, 4Goldschleger Eye Research Institute, Tel-Aviv University, Sheba Medical Center, Tel HaShomer, IsraelPurpose: Evaluation of the neuroprotective effect of weekly glatiramer acetate (GA on retinal structure and function in diabetic patients who underwent panretinal photocoagulation (PRP.Patients and methods: Patients with severe nonproliferative or early proliferative diabetic retinopathy and no previous laser treatment were randomly divided into two groups: (1 those who received four GA treatments and (2 those who received placebo treatment. The subcutaneous injections were administered 1 week prior to laser and weekly in the subsequent three sessions of PRP in both groups. All patients underwent a full ophthalmic examination (best-corrected logMAR visual acuity, slit lamp examination, applanation tonometry, fundus biomicroscopy and indirect fundus examination; functional examination (standard automated perimetry, electroretinography and frequency-doubling technology C-20 visual field and anatomic examination (color photography, optical coherence tomography (OCT and Heidelberg retinal tomography. The examinations were performed before the photocoagulation and repeated 1,3,6, and 12 months after treatment (in a double-masked manner. To compare the two groups, generalized estimating equation models were performed to account for the dependence between eyes of the same patient.Results: Thirteen patients (23 eyes were included in the study group and 13 patients (24 eyes were included in the control group. OCT

  6. [Lack of correlation between retinal variables before treatment and poor functional response after focal photocoagulation in diabetic macular oedema].

    Science.gov (United States)

    Ávila-Alcaraz, Yoloxochilth; Razo Blanco-Hernández, Dulce Milagros; García-Rubio, Yatzul Zuhaila; Lima-Gómez, Virgilio

    2016-01-01

    Although photocoagulation reduces the incidence of moderate visual loss in eyes with focal diabetic macular oedema, some eyes may lose some vision after treatment. The proportion of eyes with poor functional response after photocoagulation, and whether any retinal variable is associated with this, is unknown. To determine the proportion of eyes with diabetic macular oedema that have a poor functional response after focal photocoagulation, and their associated features. A non-experimental, longitudinal, comparative and retrospective study was conducted. The proportion and 95% confidence intervals (CI) of diabetics with macular oedema that had a poor functional response after focal photocoagulation (any visual loss after 6 weeks) were identified. The means of retinal variables before treatment were compared between eyes with and without a poor functional response using the Student t test for independent means. The study included 115 eyes of patients aged 59.3 (SD 9.24) years. Visual acuity was greater than or equal to 0.5 in 63 eyes (54.8%). A total of 33 eyes had a poor functional response after photocoagulation (28.7%, 95% CI: 13.3 to 44.1). The comparison between retinal variables and visual acuity before treatment did not show any differences between eyes with or without a poor functional response and eyes. Retinal thickening and visual acuity improved or did not change in 71.3% of eyes with diabetic macular oedema with a single photocoagulation procedure. Retinal variables that are usually evaluated were unable to identify the remaining 28.7%, which could lose vision after that treatment, and would require additional interventions. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.

  7. Combined treatment with intravitreal bevacizumab and laser photocoagulation for exudative maculopathy in facioscapulohumeral muscular dystrophy.

    Science.gov (United States)

    Matos, Rita; Beato, João; Silva, Marta; Silva, Sérgio; Brandão, Elisete; Falcão-Reis, Fernando; Penas, Susana

    2017-01-01

    To report a rare case of exudative maculopathy in a patient with facioscapulohumeral muscular dystrophy (FSHD), and its management. Observational case report. A 62-year-old man with genetically confirmed FSHD was referred to our department complaining of decreased visual acuity in his left eye. At presentation, right eye examination was unremarkable and best-corrected visual acuity (BCVA) was 20/20. Left eye BCVA was 20/100 and it presented a dense cataract with the evidence of macular lipid exudation. Cataract surgery combined with intravitreal bevacizumab improved BCVA to 20/20. Postoperative fundus examination disclosed focal macular retinal microvascular dilations with lipid exudation inferotemporal to the fovea. Fluorescein angiography highlighted these macular telangiectatic abnormalities but no peripheral lesions were detected. Spectral domain optical coherence tomography (SD-OCT) showed mild temporal retinal thickening, sparing the fovea. A diagnosis of exudative maculopathy due to macular telangiectasia secondary to FSHD was established. One year later, his left eye vision dropped to 20/32 and macular SD-OCT showed an aggravation of the intraretinal fluid and exudation. He was then submitted to a second intravitreal injection of bevacizumab followed by one angio-guided focal laser photocoagulation session, with a significant improvement. Twelve months later, his BCVA remained 20/20 on both eyes with no recurrence of exudation. The present work shows that in cases of visual-threatening macular exudation, intravitreal anti-vascular endothelial growth factor injections combined with focal laser photocoagulation may be a safe and effective treatment. This article also highlights that all FSHD patients should be screened for asymptomatic retinal vascular disorders.

  8. Treatment of presumed iris melanoma in dogs by diode laser photocoagulation: 23 cases.

    Science.gov (United States)

    Cook, Cynthia S.; Wilkie, David A.

    1999-01-01

    A semiconductor diode laser was used to cause remission of isolated presumed iris melanoma in 23 dogs. All cases presented as unilateral areas of raised iris hyperpigmentation, ranging in size from 2x 3 mm to 4x12 mm. Cases were treated using a diode laser delivery system through either an operating microscope adapter (OMA) or a laser indirect ophthalmoscope (LIO) with a 20D lens. Laser treatment was delivered 'to effect' using power ranging from 80 to 1000 mW and cumulative durations up to 14 min, 31 s (14:31). Immediate shrinkage of the mass was noted following treatment. Five cases required more than one laser treatment with three eyes receiving two treatments and two eyes receiving three treatments. Follow-up from the last laser treatment ranged from 6 months to 4.5 years during which time the lesions exhibited no enlargement. Minor complications related to laser treatment were seen, including: dyscoria, iris hyperpigmentation, and corneal edema due to collateral hyperthermia. Glaucoma and cataract formation were not observed. Non-invasive diode laser photocoagulation appears to be a safe and effective method of treatment for isolated, pigmented iris masses in dogs.

  9. Research progress on combined therapy of traditional Chinese medicine with laser photocoagulation for treatment of diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Xue-Zheng Sun

    2015-07-01

    Full Text Available Diabetic retinopathy(DRis the most severe complication of diabetic eye disease, which can eventually lead to irreversible blindness, thus seriously impacting on patients' quality of life. At present, surgical operation has been widely carried out on the treatment of DR in China. For the pre proliferative DR(PDRand PDR, panretinal photocoagulation has often been adopted. By damaging the retina in ischemic area so as to reduce oxygen demand, the neovascularization can be prevented and the patient's condition can be stopped from getting worse. Traditional Chinese medicine(TCMhas an abundant and personalized therapeutic regimen for the treatment of DR. This paper reviews the research progress on combined therapy of TCM with laser photocoagulation for treatment of DR.

  10. A comparison of argon and diode photocoagulation combined with supplemental oxygen for the treatment of retinopathy of prematurity.

    Science.gov (United States)

    Benner, J D; Morse, L S; Hay, A; Landers, M B

    1993-01-01

    The efficacy of argon and diode laser photocoagulation of the avascular peripheral retina for threshold retinopathy of prematurity (ROP) was compared in a prospective trial. The study group included 9 premature infants (17 eyes). In each infant, one eye was treated with the diode laser indirect ophthalmoscope (LIO), and the fellow eye was treated with the argon LIO. Supplemental oxygen therapy was administered after laser treatment to all nine infants. The mean duration of the follow-up period was 9.7 +/- 2.6 months. All 17 eyes (100%) had complete regression of ROP and favorable outcomes. The diode and argon LIO appear to be equally effective in treating threshold ROP. Two patients sustained burns of the tunica vasculosa lentis and anterior lens capsule in the argon laser treated eye but not in the fellow diode treated eye. Photocoagulation with either the diode or argon LIO, combined with supplemental oxygen treatment, appears to be a promising treatment for retinopathy of prematurity.

  11. Photochemical injury to the foveomacula of the monkey eye following argon blue-green panretinal photocoagulation.

    OpenAIRE

    Parver, L M

    2000-01-01

    PURPOSE: Visual loss following panretinal photocoagulation was found in the Diabetic Retinopathy and the Early Treatment Diabetic Retinopathy Studies. This study was designed to test the hypothesis that light scattered in the monkey eye during a procedure designed to mimic a clinical panretinal photocoagulation (PRP) can produce a photochemical injury to the foveomacula. METHODS: Ten eyes of 5 adult cynomologous monkeys underwent a PRP using an argon blue-green laser. Three eyes in 2 monkeys ...

  12. Transscleral cyclodiode laser photocoagulation in the treatment of aqueous misdirection syndrome.

    Science.gov (United States)

    Stumpf, Thomas H; Austin, Michael; Bloom, Philip A; McNaught, Andrew; Morgan, James E

    2008-11-01

    To describe the outcome of using transscleral cyclodiode laser ciliary body ablation as a novel treatment for aqueous misdirection syndrome. Retrospective case series review. Five patients diagnosed with aqueous misdirection syndrome. Patients successfully managed using transscleral cyclodiode laser. To evaluate demographic information, risk factors, visual acuity, medical treatment, intraocular pressure (IOP) control, and complications. The patients were aged 27 to 78 years and 3 were female. All were hyperopic, with narrow iridocorneal angles and patent peripheral iridotomies (PI). Four developed aqueous misdirection syndrome after intraocular surgery and 1 developed it spontaneously in the presence of a patent PI after losing vision in the fellow eye to the same condition 8 years earlier. All 5 patients responded to transscleral cyclodiode laser photocoagulation with rapid deepening of the anterior chamber; 1 patient required a second treatment 1 year later. All patients had good long-term vision and IOP control. The outcome of transscleral cyclodiode ciliary body ablation in these patients supports the use of this technique in cases of aqueous misdirection syndrome where medical treatment has not been sufficient to control the IOP.

  13. Bilateral Hypertensive Retinopathy Complicated with Retinal Neovascularization: Panretinal Photocoagulation or Intravitreal Anti-VEGF Treatment?

    Science.gov (United States)

    Georgiadis, Odysseas; Kabanarou, Stamatina A; Batsos, Georgios; Feretis, Elias; Xirou, Tina

    2014-05-01

    To present the case of a patient with bilateral hypertensive retinopathy complicated with retinal neovascularization who received anti-VEGF intravitreal injection in one eye and panretinal photocoagulation (PRP) in the fellow eye. A 33-year-old male patient presented with gradual visual loss in both eyes for the last 5 months. At that time, he was examined by an ophthalmologist and occlusive retinopathy due to malignant systematic hypertension was diagnosed. He was put on antihypertensive treatment but no ophthalmic treatment was undertaken. At presentation, 5 months later, best-corrected visual acuity (BCVA) was 0.1 in the right eye (RE) and 0.9 in the left eye (LE). Fundus examination was compatible with hypertensive retinopathy complicated with retinal neovascularization. Fluorescein angiography (FFA) revealed macular ischemia mainly in the RE and large areas of peripheral retinal ischemia and neovascularization with vascular leakage in both eyes. The patient was treated with two anti-VEGF (ranibizumab) injections with 2 months interval in the RE and PRP laser in the LE. Follow-up examination after 12 months showed mild improvement in BCVA, and FFA documented regression of retinal neovascularization in both eyes. Hypertensive retinopathy can be rarely complicated with retinal neovascularization. Treatment with PRP can be undertaken. In our case, the use of an intravitreal anti-VEGF agent seemed to halt its progression satisfactorily.

  14. Pattern scan laser versus single spot laser in panretinal photocoagulation treatment for proliferative diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Shu Zhang

    2017-02-01

    Full Text Available AIM: To investigate the efficacy of 577-nm pattern scan laser in panretinal photocoagulation(PRPtreatment in newly diagnosed proliferative diabetic retinopathy(PDR.METHODS:Prospective and comparative observation was performed in totally 32 patients with high-risk PDR. They were randomly divided into group 1(using pattern scan laser, PSLand 2(using single spot laser, SSL, each containing 16 subjects to which totally 20 eyes received PRP. Non-perfusion region was identified with fundus fluorescein angiography(FFAbefore and 3mo after final PRP. The advantage of PSL was verified in terms of the number and the duration of PRP sessions needed for satisfactory outcomes, and the pain score.RESULTS: Three PRP sessions were needed for each eye to complete the treatment using PSL, while 4 sessions were needed using SSL. The duration of each session with PSL in group 1 was 7.3±2.3min, which was significantly shorter than that with SSL in group 2(13.2±4.1, t38=5.596, PPCONCLUSION: PSL showed clear advantages over SSL in the PRP treatment of PDR, not only in the improved efficacy, but also in the reduction of pain and the improvement of effectiveness.

  15. Subthreshold diode-laser micropulse photocoagulation as a primary and secondary line of treatment in management of diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Othman IS

    2014-03-01

    Full Text Available Ihab Saad Othman,1 Sherif Ahmed Eissa,1 Mohamed S Kotb,1 Sherin Hassan Sadek21Cairo University, Cairo, 2Fayoum University, Al Fayoum, EgyptBackground: The purpose of this study was to evaluate subthreshold diode-laser micropulse (SDM photocoagulation as a primary and secondary line of treatment for clinically significant diabetic macular edema (CSDME.Methods: In this prospective nonrandomized case series, 220 cases of nonischemic CSDME were managed primarily and secondarily by SDM photocoagulation on a 15% duty cycle with a mean power of 828 mW and a spot size of 75–125 µm. SDM treatment was repeated at 3–4-month intervals if residual leakage was observed. Additional intravitreal pharmacologic therapy was used according to the response. Follow-up varied from 12 to 19 (mean 14±2.8 months. Novel software designed by the authors was used to record the subvisible threshold laser applications and their parameters on the fundus image of the eye. Evaluation of the results of treatment was done using fluorescein angiography and optical coherence tomography (OCT. Primary outcome measures included changes in visual acuity and foveal thickness at OCT. Secondary outcome measures included visual loss of one or more Snellen lines and laser scars detectable on fundus biomicroscopy or fluorescein angiography.Results: In the primary treatment group, there was significant improvement or stabilization of visual acuity after the first 3–4 months, which was stable thereafter. Visual acuity was stable in the secondary treatment group. A corresponding reduction of macular thickness on OCT was noted during the follow-up period in both groups. Additional therapy included repeat SDM photocoagulation, intravitreal injection of triamcinolone, and pars plana vitrectomy. Laser marks seen as changes in retinal pigment epithelium on fundus biomicroscopy and fluorescein angiography were noted in 3.3% and 5.7% of cases. Our novel software could accurately record the

  16. Automatic temperature controlled retinal photocoagulation

    Science.gov (United States)

    Schlott, Kerstin; Koinzer, Stefan; Ptaszynski, Lars; Bever, Marco; Baade, Alex; Roider, Johann; Birngruber, Reginald; Brinkmann, Ralf

    2012-06-01

    Laser coagulation is a treatment method for many retinal diseases. Due to variations in fundus pigmentation and light scattering inside the eye globe, different lesion strengths are often achieved. The aim of this work is to realize an automatic feedback algorithm to generate desired lesion strengths by controlling the retinal temperature increase with the irradiation time. Optoacoustics afford non-invasive retinal temperature monitoring during laser treatment. A 75 ns/523 nm Q-switched Nd:YLF laser was used to excite the temperature-dependent pressure amplitudes, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. A 532 nm continuous wave Nd:YAG laser served for photocoagulation. The ED50 temperatures, for which the probability of ophthalmoscopically visible lesions after one hour in vivo in rabbits was 50%, varied from 63°C for 20 ms to 49°C for 400 ms. Arrhenius parameters were extracted as ΔE=273 J mol-1 and A=3.1044 s-1. Control algorithms for mild and strong lesions were developed, which led to average lesion diameters of 162+/-34 μm and 189+/-34 μm, respectively. It could be demonstrated that the sizes of the automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

  17. Improved external valvuloplasty, intravenous laser photocoagulation and local sclerotheraphy treatment of primary deep venous valvular insufficiency: long term result

    Science.gov (United States)

    Wang, Chun-xi; Han, Li-na; Gu, Ying; Liang, Fa-qi; Zhang, Li; Liu, Hong-yi; Zhao, Wen-guang; Wang, Qi; Wang, Xiao-ling

    2007-11-01

    The purpose of this article is to report long-term follow-up of improved external vulvuloplasty, intravenous laser photocoagulation and local sclerotherapy treatment of primary deep venous valvular insufficiency in eight hundred and seventy-two patients from Nov. 2000 to May 2006. Patients were evaluated clinically and with duplex ultrasound at 1, 3, and 12 months, and yearly thereafter until the fifth year to assess treatment efficacy and adverse reactions. Successful occlusion of the great saphenous vein and absence of deep vein reflux on color Doppler imaging, were noted in 956 limbs of 852 cases( 1 month follow-up), 946 limbs of 842 cases (6 month to 1 year follow-up), 717 of 626 (1~2 year follow-up), 501 of 417 (2~3 year follow-up), 352 of 296 (3~5year follow-up), 142 of 106 (5 year follow-up) after initial treatment. The cumulative total number of recurrence of reflux was fifteen cases. The respective competence rate was 95.18%, 96.23%, 94.23%, 95.25%, 94.23% and 94.12%. Of note, all recurrence occurred before 9 months, with the majority noted before 3 months. Bruising was noted in 0.7% of patients, tightness along the course of treated vein in 1.0% of limbs. There have been no paresthesia of cases, skin burns and deep vein thrombosis.

  18. Efficacy of intravitreal injection of Ranibizumab combined with laser photocoagulation in treatment of macular edema secondary to branch retina vein occlusion

    Directory of Open Access Journals (Sweden)

    Rui-Fang Yang

    2016-01-01

    Full Text Available AIM:To observe the effect and safety of Ranibizumab intravitreal injection combined with laser photocoagulation in treatment of macular edema secondary to branch retina vein occlusion(BRVO.METHODS:Forty-four patients(44 eyeswith macular edema secondary to BRVO were enrolled. Patients received intravitreal injection of ranibizumab(0.05mL/0.5mgand laser photocoagulation(ranibizumab groupor laser photocoagulation alone(control group. Patients in ranibizumab group were given laser photocoagulation at 1mo after intravitreal injection. Then ranibizumab was given again if needed. The best corrected visual acuity(BCVA, slitlamp examination, fundus examination, non-contact tonometer examination and fundus fluorescein angiography were taken. All patients were followed up for 6mo. We analyzed the changes on BCVA,central macular thickness(CMTbefore and 1,4,12 and 24wk after treatments, and related complications were recorded. RESULTS:Outcomes are significantly better in ranibizumab group with reduced retinal thickness and improved visual acuity. In ranibizumab group, both visual acuity and CMT values were significantly better than those before treatments(visual acuity:t=5.781,7.496,7.341,7.836, all P=0.000; CMT:t=9.784,11.893,11.573,11.437, all P=0.000.In control group, the improvement on visual acuity was not significantly better than that before treatment at 1wk(t=2.130,P=0.053; while the improvement on visual acuity was significantly better at 4,12 and 24wk(t=3.524,6.429,6.922,P=0.04,0.000,0.000.The improvements on visual acuity after treatments in ranibizumab group were significantly better than those in control group at 1,4,12 and 24wk(t=2.604,3.223,3.303,3.296,P=0.015,0.03,0.04,0.03.CMT values after treatments in ranibizumab group were significantly better than those in contral group at 1,4,12 and 24wk(t=43.231,50.504,56.074,38.103,all P=0.000.No severe ocular and systematic side effect was found.CONCLUSION:Intravitreal injection of ranibizumab

  19. Laser photocoagulation for retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    K. A. Mirzabekova

    2015-03-01

    Full Text Available Retinal vein occlusion (RVO is one of the leading causes of permanent vision loss. In adults, central retinal vein occlusion (CRVO occurs in 1.8% while branch retinal vein occlusion (BRVO occurs in 0.2%. Treatment strategy and disease prognosis are determined by RVO type (ischemic/non-ischemic. Despite numerous studies and many current CRVO and BRVO treatment approaches, the management of these patients is still being debated. Intravitreal injections of steroids (triamcinolone acetate, dexamethasone and vascular endothelial growth factor (VEGF inhibitors (bevacizumab, ranibizumab were shown to be fairly effective. However, it is unclear whether anti-VEGF agents are reasonable in ischemic RVOs. Laser photocoagulation remains the only effective treatment of optic nerve head and/or retinal neovascularization. Laser photocoagulation is also indicated for the treatment of macular edema. Both threshold and sub-threshold photocoagulation may be performed. Photocoagulation performed with argon (514 nm, krypton (647 nm, or diode (810 nm laser for macular edema provides similar results (no significant differences. The treatment may be complex and include medication therapy and/or surgery. Medication therapy includes anti-aggregant agents and antioxidants, i.e., emoxypine which may be used in acute RVO as well as in post-thrombotic retinopathy. 

  20. Laser photocoagulation for retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    K. A. Mirzabekova

    2015-01-01

    Full Text Available Retinal vein occlusion (RVO is one of the leading causes of permanent vision loss. In adults, central retinal vein occlusion (CRVO occurs in 1.8% while branch retinal vein occlusion (BRVO occurs in 0.2%. Treatment strategy and disease prognosis are determined by RVO type (ischemic/non-ischemic. Despite numerous studies and many current CRVO and BRVO treatment approaches, the management of these patients is still being debated. Intravitreal injections of steroids (triamcinolone acetate, dexamethasone and vascular endothelial growth factor (VEGF inhibitors (bevacizumab, ranibizumab were shown to be fairly effective. However, it is unclear whether anti-VEGF agents are reasonable in ischemic RVOs. Laser photocoagulation remains the only effective treatment of optic nerve head and/or retinal neovascularization. Laser photocoagulation is also indicated for the treatment of macular edema. Both threshold and sub-threshold photocoagulation may be performed. Photocoagulation performed with argon (514 nm, krypton (647 nm, or diode (810 nm laser for macular edema provides similar results (no significant differences. The treatment may be complex and include medication therapy and/or surgery. Medication therapy includes anti-aggregant agents and antioxidants, i.e., emoxypine which may be used in acute RVO as well as in post-thrombotic retinopathy. 

  1. Real-time temperature determination during retinal photocoagulation on patients

    Science.gov (United States)

    Brinkmann, Ralf; Koinzer, Stefan; Schlott, Kerstin; Ptaszynski, Lars; Bever, Marco; Baade, Alexander; Luft, Susanne; Miura, Yoko; Roider, Johann; Birngruber, Reginald

    2012-06-01

    The induced thermal damage in retinal photocoagulation depends on the temperature increase and the time of irradiation. The temperature rise is unknown due to intraocular variations in light transmission, scattering and grade of absorption in the retinal pigment epithelium (RPE) and the choroid. Thus, in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which can lead to extended neuroretinal damage and strong pain perception. This work focuses on an optoacoustic (OA) method to determine the temperature rise in real-time during photocoagulation by repetitively exciting thermoelastic pressure transients with nanosecond probe laser pulses, which are simultaneously applied to the treatment radiation. The temperature-dependent pressure amplitudes are non-invasively detected at the cornea with an ultrasonic transducer embedded in the contact lens. During clinical treatment, temperature courses as predicted by heat diffusion theory are observed in most cases. For laser spot diameters of 100 and 300 μm, and irradiation times of 100 and 200 ms, respectively, peak temperatures range between 70°C and 85°C for mild coagulations. The obtained data look very promising for the realization of a feedback-controlled treatment, which automatically generates preselected and reproducible coagulation strengths, unburdens the ophthalmologist from manual laser dosage, and minimizes adverse effects and pain for the patient.

  2. Realtime temperature determination during retinal photocoagulation on patients

    Science.gov (United States)

    Brinkmann, Ralf; Koinzer, Stefan; Schlott, Kerstin; Ptaszynski, Lars; Bever, Marco; Baade, Alex; Miura, Yoko; Birngruber, Reginald; Roider, Johann

    2011-03-01

    Retinal photocoagulation is a long time established treatment for a variety of retinal diseases, most commonly applied for diabetic macular edema and diabetic retinopathy. The damage extent of the induced thermal coagulations depend on the temperature increase and the time of irradiation. So far, the induced temperature rise is unknown due to intraocular variations in light transmission and scattering and RPE/choroidal pigmentation, which can vary inter- and intraindividually by more than a factor of four. Thus in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which lead to extended retinal damage and strong pain perception. The final goal of this project focuses on a dosimetry control, which automatically generates a desired temperature profile and thus coagulation strength for every individual coagulation spot, ideally unburden the ophthalmologist from any laser settings. In this paper we present the first realtime temperature measurements achieved on patients during retinal photocoagulation by means of an optoacoustic method, making use of the temperature dependence of the thermal expansion coefficient of retinal tissue. Therefore, nanosecond probe laser pulses are repetitively and simultaneously applied with the treatment radiation in order to excite acoustic waves, which are detected at the cornea with an ultrasonic transducer embedded in the contact lens and then are processed by PC.

  3. Transscleral and indirect ophthalmoscope diode laser retinal photocoagulation: experimental quantification of the therapeutic range for their application in the treatment of retinopathy of prematurity.

    Science.gov (United States)

    Obana, A; Lorenz, B; Birngruber, R

    1993-07-01

    Laser indirect ophthalmoscope (LIO) photocoagulation and transscleral photocoagulation through the conjunctiva and subconjunctiva were performed in the fundus of chinchilla gray rabbits using various exposure times and powers, and the thresholds for retinal blanching and choroidal hemorrhage were determined. The therapeutic range was described for both applications as the ratio between energy values to produce grayish white lesions and hemorrhage at 50% probability. The therapeutic range appeared to remain almost constant with different exposure times. The mean ratio with LIO was 3.2 +/- 0.28, similar to that with slit-lamp delivery reported in our previous study. The mean ratio with transscleral photocoagulation through the conjunctiva and subconjunctiva were 2.48 +/- 0.28 and 2.38 +/- 0.26, respectively. The variability of LIO appeared to be a little lower than with transscleral photocoagulation. There was no significant difference between the variability with transscleral photocoagulation through the conjunctiva and subconjunctiva.

  4. Selective fetoscopic laser photocoagulation of superficial placental anastomoses for the treatment of severe twin-twin transfusion syndrome

    Directory of Open Access Journals (Sweden)

    Rodrigo Ruano

    2009-02-01

    Full Text Available OBJECTIVE: To report our initial institutional experience with fetoscopic laser photocoagulation of placental anastomoses in severe twin-twin transfusion syndrome using a 1.0 mm endoscope. METHODS: Between July 2006 and June 2008, 19 monochorionic diamniotic twin pregnancies complicated by severe TTTS (Quintero stages III and IV underwent fetoscopic laser therapy. Perinatal data were prospectively collected and compared according to the Quintero stages. RESULTS: Nine patients were classified as stage III and ten as stage IV. The Mean gestational ages at diagnosis and procedure were 20 (range: 17-25 and 22.0 (range: 19.0-26.0 weeks, respectively, with no statistical difference between the two groups. Preterm premature rupture of the membranes occurred in two cases (10.5%, and spontaneous preterm delivery in eight (42.1%. Overall mean gestational age at delivery was 32.1 (range: 26.0-38.0 weeks. Prematurity was more severe in stage IV patients (p<0.01. Among all cases, the overall survival rate was 52.6%, and the percentages of pregnancies with survival of both babies and at least one twin were 26.3% and 78.9%, respectively. In the case of stage III patients, the overall survival rate was 61.1%. Of the stage III pregnancies, 33.3% resulted in both babies surviving, and 88.9% of these pregnancies resulted in at least one surviving twin. For stage IV, as the corresponding statistics were 45.0%, 20.0% and 70.0% respectively. CONCLUSIONS: Our initial institutional experience with 1.0 mm fetoscopic laser therapy for severe TTTS showed results similar to those reported in the literature for larger endoscopes.

  5. Pars plana vitrectomy with juxtapapillary laser photocoagulation versus vitrectomy without juxtapapillary laser photocoagulation for the treatment of optic disc pit maculopathy: the results of the KKESH International Collaborative Retina Study Group.

    Science.gov (United States)

    Abouammoh, Marwan A; Alsulaiman, Sulaiman M; Gupta, Vishali S; Mousa, Ahmed; Hirakata, Akito; Berrocal, Maria H; Chenworth, Megan; Chhablani, Jay; Oshima, Yusuke; AlZamil, Waseem M; Casella, Antonio Marcelo; Papa-Oliva, Gabriela; Banker, Alay S; Arevalo, J Fernando

    2016-04-01

    To compare the functional and anatomic outcomes of pars plana vitrectomy (PPV) with juxtapapillary laser photocoagulation (JLP) versus vitrectomy without JLP in optic disc pit maculopathy. This was a multicentre, retrospective study of 46 consecutive patients with optic disc pit maculopathy presenting at tertiary eye centres between 1992 and 2012. Indications for surgery included distorted or decreased vision. Surgical intervention included PPV, posterior vitreous detachment, with or without gas tamponade. Twenty-four patients received laser photocoagulation at the temporal edge of the optic disc pit (group A) and 22 patients had no laser (group B). Postoperative best-corrected visual acuity (BCVA) and optical coherence tomography findings were the main outcome measures. Mean follow-up was 44 months (range 12-98 months). BCVA in group A improved significantly from 0.7 logMAR (20/100) preoperatively to 0.5 logMAR (20/60) postoperatively (p=0.017). In group B, BCVA improved from 0.7 logMAR (20/100) preoperatively to 0.4 logMAR (20/40) postoperatively (p=0.014). The difference in final BCVA between groups was not statistically significant (p=0.693). The mean central macular thickness (CMT) in group A improved significantly from 750 μm preoperatively to 309 μm at last follow-up (pmaculopathy had similar functional and anatomic outcomes compared with vitrectomy without JLP. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  6. Treatment of diffuse diabetic maculopathy with intravitreal triamcinolone and laser photocoagulation: randomized clinical trial with morphological and functional evaluation

    National Research Council Canada - National Science Library

    Gil, Alberto Luiz; Azevedo, Mirela Jobim de; Tomasetto, Giovani Generali; Muniz, Carlos Henrique Gervini; Lavinsky, Jacó

    2011-01-01

    .... The purpose of this double blind randomized clinical trial was to compare the treatment of diffuse diabetic macular edema with intravitreal triamcinolone or laser in type 2 diabetes mellitus patients...

  7. Efficacy of anti-VEGF and laser photocoagulation in the treatment of visual impairment due to diabetic macular edema: a systematic review and network meta-analysis.

    Directory of Open Access Journals (Sweden)

    Stephane Régnier

    Full Text Available Compare the efficacy of ranibizumab, aflibercept, laser, and sham in the first-line treatment of diabetic macular edema (DME to inform technology assessments such as those conducted by the UK National Institute for Health and Care Excellence (NICE.MEDLINE, Embase, Cochrane Library, congress abstracts, ClinicalTrials.gov registry and Novartis data on file.Studies reporting 6- or 12-month results of randomized controlled trials (RCTs evaluating at least two of ranibizumab 0.5 mg pro re nata, aflibercept 2.0 mg bi-monthly, laser photocoagulation or sham. Study quality was assessed based on likelihood of bias in selection, attrition, detection and performance.Improvement in best-corrected visual acuity (BCVA measured as the proportion of patients gaining ≥10 letters on the Early Treatment Diabetic Retinopathy Study scale. The outcome was chosen following acceptance by NICE of a Markov model with 10-letter health states in the assessment of ranibizumab for DME.Bayesian network meta-analyses with fixed and random effects adjusted for differences in baseline BCVA or central retinal thickness.The analysis included 1,978 patients from eight RCTs. The random effects model adjusting for baseline BCVA was the best model based on total residual. The efficacy of ranibizumab was numerically, but not statistically, superior to aflibercept (odds ratio [OR] 1.59; 95% credible interval [CrI], 0.61-5.37. Ranibizumab and aflibercept were statistically superior to laser monotherapy with ORs of 5.50 (2.73-13.16 and 3.45 (1.62-6.84 respectively. The probability that ranibizumab is the most efficacious treatment was 73% compared with 14% for aflibercept, 12% for ranibizumab plus laser, and 0% for laser.Three of the eight RCTs included are not yet published. The models did not adjust for all potential effect modifiers.Ranibizumab was non-significantly superior to aflibercept and both anti-VEGF therapies had statistically superior efficacy to laser.

  8. Treatment of diffuse diabetic maculopathy with intravitreal triamcinolone and laser photocoagulation: randomized clinical trial with morphological and functional evaluation

    Directory of Open Access Journals (Sweden)

    Alberto Luiz Gil

    2011-10-01

    Full Text Available PURPOSE: Treatment of diffuse macular edema in diabetes mellitus is currently unsatisfactory. The purpose of this double blind randomized clinical trial was to compare the treatment of diffuse diabetic macular edema with intravitreal triamcinolone or laser in type 2 diabetes mellitus patients using a morphofunctional assessment. METHODS: Fourteen patients (21 eyes with clinically significant diffuse macular-edema, previously untreated and with a macular thickness >250 µm at optical coherence tomography were randomized for treatment with laser or intravitreal injection of triamcinolone acetate. Optical coherence tomography, biomicroscopy, fundoscopy, fluorescein angiography, tonometry, scotometry, visual and contrast acuities were performed at 0, 1, 3 and 6 months. RESULTS: At pre-treatment stage, Laser (n=9 and Triamcinolone (n=12 groups did not differ regarding retinal thickness, visual and contrast acuities. In Triamcinolone group macular thickness decreased after 1 month (424.1 ± 19.9 µm to 358.4 ± 18.2 µm; p=0.04 and started to return to the initial values in the 3rd month (p=0.02. No changes occurred in macular scotometry and visual and contrast acuities. No side effects were observed with both treatments. CONCLUSION: During the study macular thickness diminished in the triamcinolone group, especially in the first month of treatment. At 3 and 6 months there was no difference. Macular thickness did not change during the study in the laser group. In the study sample it was not possible to demonstrate differences relates to visual acuity and scotometry between the two groups. CLINICALTRIALS.GOV IDENTIFIER: NCT00668239

  9. Treatment of diffuse diabetic maculopathy with intravitreal triamcinolone and laser photocoagulation: randomized clinical trial with morphological and functional evaluation.

    Science.gov (United States)

    Gil, Alberto Luiz; Azevedo, Mirela Jobim de; Tomasetto, Giovani Generali; Muniz, Carlos Henrique Gervini; Lavinsky, Jacó

    2011-01-01

    Treatment of diffuse macular edema in diabetes mellitus is currently unsatisfactory. The purpose of this double blind randomized clinical trial was to compare the treatment of diffuse diabetic macular edema with intravitreal triamcinolone or laser in type 2 diabetes mellitus patients using a morphofunctional assessment. Fourteen patients (21 eyes) with clinically significant diffuse macular-edema, previously untreated and with a macular thickness >250 µm at optical coherence tomography were randomized for treatment with laser or intravitreal injection of triamcinolone acetate. Optical coherence tomography, biomicroscopy, fundoscopy, fluorescein angiography, tonometry, scotometry, visual and contrast acuities were performed at 0, 1, 3 and 6 months. At pre-treatment stage, Laser (n=9) and Triamcinolone (n=12) groups did not differ regarding retinal thickness, visual and contrast acuities. In Triamcinolone group macular thickness decreased after 1 month (424.1 ± 19.9 µm to 358.4 ± 18.2 µm; p=0.04) and started to return to the initial values in the 3(rd) month (p=0.02). No changes occurred in macular scotometry and visual and contrast acuities. No side effects were observed with both treatments. During the study macular thickness diminished in the triamcinolone group, especially in the first month of treatment. At 3 and 6 months there was no difference. Macular thickness did not change during the study in the laser group. In the study sample it was not possible to demonstrate differences relates to visual acuity and scotometry between the two groups. CLINICALTRIALS.GOV IDENTIFIER: NCT00668239.

  10. A prospective randomized multicenter trial of amnioreduction versus selective fetoscopic laser photocoagulation for the treatment of severe twin–twin transfusion syndrome

    Science.gov (United States)

    Crombleholme, Timothy M.; Shera, David; Lee, Hanmin; Johnson, Mark; D’Alton, Mary; Porter, Flint; Chyu, Jacquelyn; Silver, Richard; Abuhamad, Alfred; Saade, George; Shields, Laurence; Kauffman, David; Stone, Joanne; Albanese, Craig T.; Bahado-Singh, Ray; Ball, Robert H.; Bilaniuk, Larissa; Coleman, Beverly; Farmer, Diana; Feldstein, Vickie; Harrison, Michael R.; Hedrick, Holly; Livingston, Jeffrey; Lorenz, Robert P.; Miller, David A.; Norton, Mary E.; Polzin, William J.; Robinson, Julian N.; Rychik, Jack; Sandberg, Per L.; Seri, Istvan; Simon, Erin; Simpson, Lynn L.; Yedigarova, Larisa; Wilson, R. Douglas; Young, Bruce

    2009-01-01

    Objective To examine the effect of selective fetoscopic laser photocoagulation (SFLP) versus serial amnioreduction (AR) on perinatal mortality in severe twin-twin transfusion syndrome (TTTS). Study Design 5-year multicenter prospective randomized controlled trial. The primary outcome variable was 30-day postnatal survival of donors and recipients. Results There is no statistically significant difference in 30-day postnatal survival between SFLP or AR treatment for donors at 55% (11/20) vs 55% (11/20) (p=1, OR=1, 95%CI=0.242 to 4.14) or recipients at 30% (6/20) vs 45% (9/20) (p=0.51, OR=1.88, 95%CI=0.44 to 8.64). There is no difference in 30-day survival of one or both twins on a per pregnancy basis between AR at 75% (15/20) and SFLP at 65% (13/20) (p=0.73, OR=1.62, 95%CI=0.34 to 8.09). Overall survival (newborns divided by the number of fetuses treated) is not statistically significant for AR at 60% (24/40) vs SFLP 45% (18/40) (p=0.18, OR=2.01, 95%CI=0.76 to 5.44). There is a statistically significant increase in fetal recipient mortality in the SFLP arm at 70% (14/20) versus the AR arm at 35% (7/20) (p=0.25, OR=5.31, 95%CI=1.19 to 27.6). This is offset by increased recipient neonatal mortality of 30% (6/20) in the AR arm. Echocardiographic abnormality in recipient twin Cardiovascular Profile Score is the most significant predictor of recipient mortality (p=0.055, OR=3.025/point) by logistic regression analysis. Conclusions The outcome of the trial does not conclusively determine whether AR or SFLP is a superior treatment modality. TTTS cardiomyopathy appears to be an important factor in recipient survival in TTTS. PMID:17904975

  11. Combination of Intravitreal Ranibizumab and Laser Photocoagulation for Aggressive Posterior Retinopathy of Prematurity

    Directory of Open Access Journals (Sweden)

    Ágata Mota

    2012-04-01

    Full Text Available Purpose: To report on 2 cases of aggressive posterior retinopathy of prematurity (ROP treated with intravitreal ranibizumab (Lucentis® and laser photocoagulation. Methods: Two premature females, born at 25 and 26 weeks’ gestation with a birth weight of 530 and 550 g, respectively, with aggressive posterior ROP received combined treatment with laser photocoagulation and intravitreal ranibizumab (0.3 mg [30 µl] to each eye. Structural outcomes were evaluated by indirect ophthalmoscopy and documented by retinography. Results: An intravitreal injection was made at 34 weeks of postmenstrual age in the first case, followed by laser photocoagulation 1 week later. There was a partial regression of ROP with treatment. Five weeks later, neovascularization regrowth with bleeding in both eyes (intraretinal and subhyaloid occurred and retreatment with combined therapy was performed. In the second case, single therapy with laser photocoagulation was made at 34 weeks of postmenstrual age. In spite of the confluent photocoagulation in the avascular area, progression to 4A ROP stage occurred 1 week later. Both eyes were retreated 1 week later with intravitreal ranibizumab and laser photocoagulation. Treatment resulted in ROP regression in both cases. There were no signs of systemic or ocular adverse side effects. Conclusion: The cases presented show that combination therapy of indirect laser photocoagulation and intravitreal ranibizumab can be effective in the management of aggressive posterior ROP. Further investigation on anti-VEGF safety in premature infants is necessary . Additional studies are needed to define the role of anti-VEGF in ROP treatment.

  12. Efficiency and safety of laser photocoagulation with or without intravitreal ranibizumab for treatment of diabetic macular edema: a systematic review and Meta-analysis

    Directory of Open Access Journals (Sweden)

    Tian-Wei Qian

    2017-07-01

    Full Text Available AIM: To compare the therapeutic effect and safety of laser photocoagulation along with intravitreal ranibizumab (IVR versus laser therapy in treatment of diabetic macular edema (DME. METHODS: Pertinent publications were identified through comprehensive searches of PubMed, EMBASE, Web of Science, Cochrane Library, and ClinicalTrials.gov to identify randomized clinical trials (RCTs comparing IVR+laser to laser monotherapy in patients with DME. Therapeutic effect estimates were determined by weighted mean differences (WMD of change from baseline in best corrected visual acuity (BCVA and central retinal thickness (CRT at 6, 12, or 24mo after initial treatment, and the risk ratios (RR for the proportions of patients with at least 10 letters of improvement or reduction at 12mo. Data regarding major ocular and nonocular adverse events (AEs were collected and analyzed. The Review Manager 5.3.5 was used. RESULTS: Six RCTs involving 2069 patients with DME were selected for this Meta-analysis. The results showed that IVR+laser significantly improved BCVA compared with laser at 6mo (WMD: 6.57; 95% CI: 4.37-8.77; P<0.00001, 12mo (WMD: 5.46; 95% CI: 4.35-6.58; P<0.00001, and 24mo (WMD: 3.42; 95% CI: 0.84-5.99; P=0.009 in patients with DME. IVR+laser was superior to laser in reducing CRT at 12mo from baseline with statistical significance (WMD: -63.46; 95% CI: -101.19 to -25.73; P=0.001. The pooled RR results showed that the proportions of patients with at least 10 letters of improvement or reduction were in favor of IVR+laser arms compared with laser (RR: 2.13; 95% CI: 1.77-2.57; P<0.00001 and RR: 0.37; 95% CI: 0.22-0.62; P=0.0002, respectively. As for AEs, the pooled results showed that a significantly higher proportion of patients suffering from conjunctival hemorrhage (study eye and diabetic retinal edema (fellow eye in IVR+laser group compared to laser group (RR: 3.29; 95% CI: 1.53-7.09; P=0.002 and RR: 3.02; 95% CI: 1.24-7.32; P=0.01, respectively. The

  13. Long-term associations between serum lipids and panretinal photocoagulation in type 1 diabetes

    DEFF Research Database (Denmark)

    Jørgensen, Jesper Skovlund; Mejnert Jørgensen, Trine; Green, Anders

    2013-01-01

    To examine the predictive value of serum lipids on the need for panretinal photocoagulation (PRP) treatment in a long-term follow-up of a cohort of Danish type 1 diabetic patients.......To examine the predictive value of serum lipids on the need for panretinal photocoagulation (PRP) treatment in a long-term follow-up of a cohort of Danish type 1 diabetic patients....

  14. Real time speckle monitoring to control retinal photocoagulation

    Science.gov (United States)

    Bliedtner, Katharina; Seifert, Eric; Brinkmann, Ralf

    2017-07-01

    Photocoagulation is a treatment modality for several retinal diseases. Intra- and inter-individual variations of the retinal absorption as well as ocular transmission and light scattering makes it impossible to achieve a uniform effective exposure with one set of laser parameters. To guarantee a uniform damage throughout the therapy a real-time control is highly requested. Here, an approach to realize a real-time optical feedback using dynamic speckle analysis in-vivo is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633 nm diode laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. An algorithm is presented that can discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes and that seems to be robust to noise in-vivo. Tissue changes in rabbits during retinal coagulation could be observed for different lesion strengths. This algorithm can run on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage.

  15. Dye-enhanced diode laser photocoagulation of choroidal neovascularizations

    Science.gov (United States)

    Klingbeil, Ulrich; Puliafito, Carmen A.; McCarthy, Dan; Reichel, Elias; Olk, Joseph; Lesiecki, Michael L.

    1994-06-01

    Dye-enhanced diode laser photocoagulation, using the dye indocyanine green (ICG), has shown some potential in the treatment of choroidal neovascularizations (CNV). A diode laser system was developed and optimized to emit at the absorption maximum of ICG. In a clinical study at two retinal centers, more than 70 patients, the majority of which had age-related macular degeneration, were treated. Eighteen cases with ill-defined subfoveal CNV were followed an average of 11 months after laser treatment. The results show success in resolving the CNV with an average long-term preservation of visual function equal to or superior to data provided by the Macular Photocoagulation Study for confluent burns of low intensity applied to the CNV. Details of the technique and discussion of the controversies inherent in such a treatment strategy will be presented.

  16. Effect of laser photocoagulation combined with calcium dobesilate for diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Zhen-Tao Zhu

    2017-02-01

    Full Text Available AIM: To investigate the clinical effect of panretinal laser photocoagulation combined with calcium hydroxide in the treatment of diabetic retinopathy(DR. METHODS: Selected 120 cases(204 eyesof DR patients who were treated in our hospital from January 2014 to December 2015 were randomly divided into study group(116 eyes in 66 patientswith calcium hydroxide, control group(88 eyes in 54 patients. Two groups were treated with panretinal laser photocoagulation, and the clinical effect of the two groups were compared. RESULTS: At 6mo after surgery, BCVA of study group was higher than that of control group, the difference was statistically significant(PPPP>0.05. CONCLUSION: Compared with simple laser photocoagulation, panretinal laser photocoagulation combined with calcium hydroxide for III - IV stage DR reduce fluorescein leakage area and CMT.

  17. Diode laser photocoagulation in PHACES syndrome hemangiomas: a case series

    Science.gov (United States)

    Romeo, U.; Russo, N.; Polimeni, A.; Favia, G.; Lacaita, M. G.; Limongelli, L.; Franco, S.

    2014-01-01

    PHACES syndrome is a pediatric syndrome with cutaneous and extra-cutaneous manifestations, such as Posterior fossa defects, Hemangiomas, Arterial lesions, Cardiac abnormalities/aortic coarctation, Eye abnormalities and Sternal cleft. Facial hemangiomas affect the 75% of patients and may arise on the oral mucosa or perioral cutaneous regions. In this study we treated 26 Intraoral Haemangiomas (IH) and 15 Perioral Haemangiomas (PH) with diode laser photocoagulation using a laser of 800+/-10nm of wavelength. For IH treatment an optical fiber of 320 μm was used, and the laser power was set ted at 4 W (t-on 200 ms / t-off 400ms; fluence: 995 J/cm2). For PH treatment an optical fiber of 400 μm at the power of 5 W was used (t-on 100 ms / t-off 300 ms; fluence: 398 J/cm2). IH healed after one session (31%), the other (69%) after two sessions of Laser therapy. In each session, only a limited area of the PH was treated, obtaining a progressive improvement of the lesion. Diode laser photocoagulation is an effective option of treatment for IH and PH in patients affected by PHACE because of its minimal invasiveness. Moreover laser photocoagulation doesn't have side effects and can be performed repeatedly without cumulative toxicity. Nevertheless, more studies are required to evaluate the effectiveness of the therapy in mid and long time period.

  18. Gas tamponade combined with laser photocoagulation therapy for congenital optic disc pit maculopathy.

    Science.gov (United States)

    Lei, L; Li, T; Ding, X; Ma, W; Zhu, X; Atik, A; Hu, Y; Tang, S

    2015-01-01

    To evaluate the long-term clinical efficacy and safety of gas tamponade combined with laser photocoagulation for optic disc pit maculopathy. Seven consecutive patients with unilateral maculopathy associated with optic disc pit and one patient with bilateral optic disc pit maculopathy were given octafluoropropane (C3F8) tamponade combined with focal laser photocoagulation treatment. Patients were followed up for 21-62 months after treatment. Main outcomes were determined by optical coherence tomography (OCT) and best-corrected visual acuity (BCVA). Treatment with C3F8 tamponade followed by laser photocoagulation in ODP maculopathy patients resulted in resolution of sub-retinal and/or intra-retinal fluid in six out of eight patients. The remaining two patients had significant reduction in fluid, as determined by OCT, and funduscopy, as well as an improvement in anatomical architecture. Visual acuity improved obviously in seven eyes and remained stable in two eyes. Central visual field loss after photocoagulation was not clinically appreciable by visual field examination. No post-operative complications of maculopathy occurred during the follow-up period. Although repeated treatment was needed in some patients, C3F8 tamponade combined with laser photocoagulation is still a simple, effective, minimally invasive, and economic therapy for optic disc pit maculopathy.

  19. Interstitial laser photocoagulation of uterine leimyoma

    Science.gov (United States)

    Gordon, Alastair D.; Buonaccorsi, Giovanni A.; Patel, Bipin L.; Broadbent, Jeff J.; Thurrell, Wendy; Bown, Stephen G.

    1996-01-01

    Uterine leiomyomas (fibroids) are common benign tumors which may cause heavy or painful periods, may present as a pelvic mass and are associated with infertility. Local excision of symptomatic lesions can be difficult and hazardous, and the alternative is hysterectomy. We are investigating interstitial laser photocoagulation (ILP) as a less invasive alternative. Initial experiments were undertaken on 40 fibroids after surgical removal. One or two bare tipped, precharred fibers from a 25 W semiconductor laser (805 nm) were inserted into the center of the fibroid and treatment delivered with 2 - 10 W for 100 - 1000 sec. Specimens were subsequently sectioned perpendicular to the fiber track. Fibroids are very pale and apart from occasional charred tracts there was little evidence of thermal coagulation macroscopically or after haematoxylon and eosin staining. However, using a diaphorase stain technique we were able to demonstrate ellipsoid zones of devitalized tissue up to 20 mm across (15 mm for single fibers). These results suggest that ILP is producing gentle, uniform coagulation which could lead to resorption of treated areas. With appropriate numbers of treatment sites, this could permit minimally invasive management of clinically significant lesions. Clinical studies have commenced treating fibroids with ILP at the time of surgical excision by myomectomy or hysterectomy.

  20. Panretinal photocoagulation versus intravitreal injection retreatment pain in high-risk proliferative diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Célia Regina Farias de Araújo Lucena

    2013-02-01

    Full Text Available PURPOSE: To compare pain related to intravitreal injection and panretinal photocoagulation in the management of patients with high-risk proliferative diabetic retinopathy. METHODS: Prospective study including patients with high-risk proliferative diabetic retinopathy and no prior laser treatment randomly assigned to receive panretinal photocoagulation (PRP group or panretinal photocoagulation plus intravitreal ranibizumab (PRPplus group. In all patients, panretinal photocoagulation was administered in two sessions (weeks 0 and 2, and intravitreal ranibizumab was administered at the end of the first laser session in the PRPplus group. Retreatment was performed at weeks 16 and 32 if active new vessels were detected at fluorescein angiography. Patients in the PRPplus group received intravitreal ranibizumab and patients in the PRP group received 500-µm additional spots per quadrant of active new vessels. After the end of retreatment, a 100-degree Visual Analog Scale was used for pain score estimation. The patient was asked about the intensity of pain during the whole procedure (retinal photocoagulation session or intravitreal ranibizumab injection. Statistics for pain score comparison were performed using a non-parametric test (Wilcoxon rank sums. RESULTS: Seventeen patients from PRPplus and 14 from PRP group were evaluated for pain scores. There were no significant differences between both groups regarding gender, glycosylated hemoglobin and disease duration. Mean intravitreal injection pain (±SEM was 4.7 ± 2.1 and was significantly lower (p<0.0001 than mean panretinal photocoagulation pain (60.8 ± 7.8. Twelve out of 17 patients from the PRPplus group referred intensity pain score of zero, while the minimal score found in PRP group was found in one patient with 10.5. CONCLUSION: In patients with high-risk proliferative diabetic retinopathy who needed retreatment for persistent new vessels, there was more comfort for the patient when retreatment

  1. Clinical therapeutic effects of intravitreal Ranibizumab injection combined laser photocoagulation for macular edema in BRVO

    Directory of Open Access Journals (Sweden)

    Bin Liu

    2014-11-01

    Full Text Available AIM: To evaluate the clinical therapeutic efficacy of intravitreal ranibizumab injection combined grid laser photocoagulation for macular edema secondary to branch retinal vein occlusion(BRVO. METHODS: Forty-two confirmed cases(42 eyeswith macular edema secondary to BRVO were randomized into 3 groups, each group contained 14 eyes. The ranibizumab group was received intravitreal injection of ranibizumab(0.05mL, the laser group was received grid laser photocoagulation, and the combined group was received a second therapy of grid laser photocoagulation after 1wk of the intravitreal injection of ranibizumab. Recorded the best-corrected visual acuity(BCVAand the central macular thickness(CMTpreoperative and at 1, 3, 6mo after therapy. RESULTS: The BCVA and the CMT had no differences among three groups pretherapy(P>0.05. While BCVA was much better and CMT was reduced significantly posttherapy than pretherapy in all three groups(PPP>0.05. While the BCVA was better and the CMT was thinner in the combined group than ranibizumab group and laser group at every time point(PPCONCLUSION: The intravitreal ranibizumab injection combined grid laser photocoagulation is an effective treatment method for the macular edema secondary to BRVO, it is more effective in improving BCVA than intravitreal ranibizumab or grid laser photocoagulation alone.

  2. Retinal hemodynamic influence of compound xueshuantong capsule on nonproliferative diabetic retinopathy after laser photocoagulation

    Directory of Open Access Journals (Sweden)

    Yu-Yan Wang

    2014-07-01

    Full Text Available AIM: To observe retinal hemodynamic influence of compound xueshuantong capsule on nonproliferative diabetic retinopathy(NPDRafter laser photocoagulation. METHODS: A total of 41 patients(72 eyeswith NPDR after laser photocoagulation were enrolled in this study. They were all given compound xueshuantong capsule, and used color Doppler flow imaging for detection of retinal hemodynamics. RESULTS: After treatment, patients with retinal blood perfusion significantly improved; central retinal arterial peak systolic velocity(PSV, end-diastolic velocity(EDVand medial velocity(Vmwere increased, while the resistance index(RIdecreased. The difference have statistical significance(PCONCLUSION: Compound xueshuantong capsule can improve retinal blood perfusion for nonproliferative diabetic retinopathy after laser photocoagulation, which is related to improvement of visual prognosis.

  3. Bullous Exudative Retinal Detachment after Retinal Pattern Scan Laser Photocoagulation in Diabetic Retinopathy

    Directory of Open Access Journals (Sweden)

    Shohei Nishikawa

    2017-10-01

    Full Text Available Laser retinal photocoagulation is the gold standard treatment for diabetic retinopathy. We describe 3 cases in which bullous exudative retinal detachment (ERD developed after pattern scan laser photocoagulation (PASCAL in diabetic retinopathy. ERD spontaneously resolved in all 3 cases with various visual courses. This case series highlights 2 key points: first, ERD can occur regardless of gender, age, glycemic control, or vitreous status and despite a moderate number of laser shots, even with PASCAL; second, ERD in nonvitrectomized eyes may cause irreversible visual loss, even if the ERD resolves within 1 month.

  4. VISUAL OUTCOME POST RETINAL LASER PHOTOCOAGULATION IN PATIENTS WITH DIABETIC RETINOPATHY

    Directory of Open Access Journals (Sweden)

    Vrunda Gangadhar Morepatil

    2017-09-01

    Full Text Available BACKGROUND Diabetes Mellitus (DM is a global epidemic with significant morbidity. Diabetic Retinopathy (DR is the specific microvascular complication of DM and affects 1 in 3 persons with DM. DR remain a leading cause of vision loss in working adult populations. Patients with severe levels of DR are reported to have poorer quality of life and reduced levels of physical, emotional and social wellbeing and they utilise more healthcare resources. The aim of the study is to determine the visual outcome of laser treatment in diabetic retinopathy patients. MATERIALS AND METHODS A total of 100 eyes of 60 patients with diabetic retinopathy in different stages were subjected to retinal laser photocoagulation using double frequency Nd:YAG laser. Focal laser was used in 9 eyes, panretinal photocoagulation was done in 55 eyes, grid and panretinal photocoagulation was done in 32 eyes and grid and focal laser was done in 2 eyes. The best corrected visual acuity was noted and fundus examination was carried out prior to photocoagulation and at follow up visits. At last follow up, results were assessed. Design- Prospective, non-comparative study. RESULTS Nonproliferative diabetic retinopathy was present in 82 eyes. Following laser treatment, best corrected visual acuity improved in 17%, remained static in 81% and deteriorated in 2%. Maculopathy improved in 11%, remained static in 89%. After laser BCVA in PDR improved in 6% and remained unchanged in 94%. In male patients following laser BCVA improved in 11%, remained static in 87% and in females BCVA improved in 23% and remained static in 74%. CONCLUSION Our study concludes that retinal laser photocoagulation plays an important role in stabilisation of vision in patients with diabetic retinopathy. There was no gender or age-related bias in the results of study. HbA1c value has no predictive role in visual outcome post retinal laser photocoagulation.

  5. Lesion strength control by automatic temperature guided retinal photocoagulation

    Science.gov (United States)

    Schlott, Kerstin; Koinzer, Stefan; Baade, Alexander; Birngruber, Reginald; Roider, Johann; Brinkmann, Ralf

    2016-09-01

    Laser photocoagulation is an established treatment for a variety of retinal diseases. However, when using the same irradiation parameter, the size and strength of the lesions are unpredictable due to unknown inter- and intraindividual optical properties of the fundus layers. The aim of this work is to investigate a feedback system to generate desired lesions of preselectable strengths by automatically controlling the irradiation time. Optoacoustics were used for retinal temperature monitoring. A 532-nm continuous wave Nd:YAG laser was used for photocoagulation. A 75-ns/523-nm Q-switched Nd:YLF laser simultaneously excited temperature-dependent pressure transients, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. The temperature data were analyzed during the irradiation by a LabVIEW routine. The treatment laser was switched off automatically when the required lesion strength was achieved. Five different feedback control algorithms for different lesion sizes were developed and tested on rabbits in vivo. With a laser spot diameter of 133 μm, five different lesion types with ophthalmoscopically visible diameters ranging mostly between 100 and 200 μm, and different appearances were achieved by automatic exposure time control. The automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

  6. Dependence of optoacoustic transients on exciting laser parameters for real-time monitoring of retinal photocoagulation

    Science.gov (United States)

    Langejürgen, J.; Schlott, K.; Bever, M.; Hausmann, K.; Koinzer, S.; Ptaszynski, L.; Roider, J.; Birngruber, R.; Brinkmann, R.

    2009-07-01

    The extent of retinal laser coagulations depends on the temperature increase at the fundus and the time of irradiation. Due to light scattering within the eye and variable fundus pigmentation the induced temperature increase and therefore the extent of the coagulations cannot be predicted solely from the laser parameters. We use optoacoustics to monitor the temperature rise in real-time in vivo (rabbit) and ex vivo (porcine eye) and to automatically control the coagulation strength. Continuous wave treatment laser radiation and pulsed probe laser light (1-1100 ns) are coupled into the same fibre and are imaged onto the retina by a laser slit lamp. The temperature dependent pressure waves are detected by an ultrasonic transducer embedded in a customary contact lens. Below the coagulation threshold the increase in acoustic amplitude due to thermal tissue expansion is up to 40 %. Best signal to noise ratios > 10 are achieved with probe pulse durations of 1 to 75 ns. Further a time critical algorithm is developed which automatically ceases laser treatment when a certain preset coagulation strength is achieved. Coagulations with similar extent are obtained with this method in vitro and in vivo even when varying the power of the treatment laser by 50 %. These preliminary results are very promising, thus this method might be suitable for an automatic feedback controlled photocoagulation with adjustable coagulation strength.

  7. CT-guided percutaneous laser photocoagulation of osteoid osteomas of the hands and feet

    Energy Technology Data Exchange (ETDEWEB)

    Zouari, Leila; Bousson, Valerie; Hamze, Bassam; Roqueplan, Francois; Laredo, Jean-Denis [Hopital Lariboisiere, Service de Radiologie Osteo-Articulaire, Paris (France); Roulot, Eric [Clinique Jouvenet, Institut de la main, Paris (France)

    2008-11-15

    Percutaneous local ablation of osteoid osteoma has largely replaced surgery, except in the small bones of the hands and feet. The objective of this study was to describe the technical specificities and results of computed tomography (CT)-guided percutaneous laser photocoagulation in 15 patients with osteoid osteomas of the hands and feet. We retrospectively examined the medical charts of the 15 patients who were treated with CT-guided percutaneous laser photocoagulation therapy at our institution between 1994 and 2004. The 15 patients had a mean age of 24.33 years. None of them had received any prior surgical or percutaneous treatment for the osteoid osteoma. The follow-up period was 24 to 96 months (mean, 49.93). The pain resolved completely within 1 week. Fourteen patients remained symptom-free throughout the follow-up period; the remaining patient experienced a recurrence of pain after 24 months, underwent a second laser photocoagulation procedure, and was symptom-free at last follow-up 45 months later. No adverse events related to the procedure or to the location of the tumor in the hand or the foot were recorded. CT-guided percutaneous laser photocoagulation is an alternative to surgery for the treatment of osteoid osteomas of the hands and feet. (orig.)

  8. Demarcation laser photocoagulation induced retinal necrosis and rupture resulting in large retinal tear formation.

    Science.gov (United States)

    Quezada, Carlos; Pieramici, Dante J; Matsui, Rodrigo; Rabena, Melvin; Graue, Federico

    2015-06-01

    Retinal tears after laser photocoagulation are a rare complication that occurs after intense laser. It is talked about among retina specialist occurring particularly at the end of a surgical case while applying endophotocoagulation; to the best our knowledge, there are no reports in the literature of a large retinal tear induced after attempted in-office demarcation laser photocoagulation (DLP) that simulated a giant retinal tear. DLP has been employed in the management of selected cases of macula sparring rhegmatogenous retinal detachment (RRD). Even though extension of the retinal detachment through the "laser barrier" is considered a failure of treatment, few complications have been described with the use of this less invasive retinal detachment repair technique. We describe a case of a high myopic woman who initially was treated with demarcation laser photocoagulation for an asymptomatic retinal detachment associated with a single horseshoe tear and a full thickness large retinal tear was created where the laser was placed. Intense laser photocoagulation resulted in abrupt laser induced retinal necrosis and rupture creating this large retinal break. Proper laser technique should reduce the risks associated with this procedure. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Combination of Anti-VEGF and Laser Photocoagulation for Diabetic Macular Edema: A Review

    Directory of Open Access Journals (Sweden)

    Laura N. Distefano

    2017-01-01

    Full Text Available Diabetic macular edema (DME is the most common cause of vision loss in diabetic patients. Thirty years ago, the Early Treatment Diabetic Retinopathy Study (ETDRS demonstrated that focal/grid laser photocoagulation reduces moderate vision loss from DME by 50% or more; thus, macular photocoagulation became the gold standard treatment for DME. However, with the development of anti-VEGF drugs (bevacizumab, ranibizumab, and aflibercept, better outcomes were obtained in terms of visual acuity gain and decrease in macular thickness in some studies when antiangiogenic drugs were administered in monotherapy. Macular laser therapy may still play an important role as an adjuvant treatment because it is able to improve macular thickness outcomes and reduce the number of injections needed. Here, we review some of the clinical trials that have assessed the efficacy of macular laser treatment, either as part of the treatment protocol or as rescue therapy.

  10. Targeted photocoagulation of peripheral ischemia to treat rebound edema

    Directory of Open Access Journals (Sweden)

    Singer MA

    2015-02-01

    Full Text Available Michael A Singer,1 Colin S Tan,2 Krishna R Surapaneni,3 Srinivas R Sadda4 1Medical Center Ophthalmology Associates, San Antonio, TX, USA; 2National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore; 3University of Texas Health Science Center at San Antonio, San Antonio, TX, USA; 4Doheny Eye Institute, Los Angeles, CA, USA Introduction: Peripheral retinal ischemia not detectable by conventional fluorescein angiography has been proposed to be a driving force for rebound edema in retinal vein occlusions. In this report, we examine the treatment of peripheral retinal ischemia with targeted retinal photocoagulation (TRP to manage a patient’s rebound edema.Methods: To assess the extent of peripheral nonperfusion, an Optos 200Tx device was used. To target the treatment to peripheral ischemia areas, a Navilas Panretinal Laser was used.Results: A 64-year-old male with a central retinal vein occlusion and a visual acuity 20/300, and central macular thickness 318 µm presented with rubeosis. Angiography revealed extensive peripheral nonperfusion. Despite TRP to areas of irreversible ischemia, after 2 months, he continued show rubeosis and rebound edema. Additional TRP laser was repeatedly added more posteriorly to areas of reversible nonperfusion, resulting in eventual resolution of rubeosis and edema.Conclusion: In this study, we demonstrate the use of widefield imaging with targeted photocoagulation of peripheral ischemia to treat rebound edema, while preserving most peripheral vision. In order to treat rebound edema, extensive TRP, across reversible and nonreversible areas of ischemia, had to be performed – not just in areas of nonreversible peripheral ischemia. These areas need to be mapped during episodes of rebound edema, when ischemia is at its maximum. In this way, by doing the most TRP possible, the cycle of rebound edema can be broken. Keywords: macular edema, retinal vein occlusion 

  11. Enhanced photocoagulation with catheter-based diffusing optical device

    Science.gov (United States)

    Kang, Hyun Wook; Kim, Jeehyun; Oh, Jungwhan

    2012-11-01

    A novel balloon catheter-based diffusing optical device was designed and evaluated to assist in treating excessive menstrual bleeding. A synthetic fused-silica fiber was micro-machined precisely to create scattering segments on a 25 mm long fiber tip for uniform light distribution. A visible wavelength (λ=532 nm) was used to specifically target the endometrium due to the high vascularity of the uterine wall. Optical simulation presented 30% wider distribution of photons along with approximately 40% higher irradiance induced by addition of a glass cap to the diffuser tip. Incorporation of the optical diffuser with a polyurethane balloon catheter considerably enhanced coagulation depth and area (i.e., 3.5 mm and 18.9 cm2 at 1 min irradiation) in tissue in vitro. The prototype device demonstrated the coagulation necrosis of 2.8±1.2 mm (n=18) and no thermal damage to myometrium in in vivo caprine models. A prototype 5 cm long balloon catheter-assisted optical diffuser was also evaluated with a cadaveric human uterus to confirm the coagulative response of the uterine tissue as well as to identify the further design improvement and clinical applicability. The proposed catheter-based diffusing optical device can be a feasible therapeutic tool to photocoagulate endometrial cell layers in an efficient and safe manner.

  12. Dynamic study of ocular hemodynamic changes on DR before and after panretinal photocoagulation

    Directory of Open Access Journals (Sweden)

    Yu-Fei Gao

    2017-07-01

    Full Text Available AIM: To explored the treatment effects of retinal laser photocoagulation and the applications of color Doppler flow imaging(CDFIin the diabetic retinopathy.METHODS: We collected 60 patients(120 eyeswith diabetic retinopathy(Ⅲ~Ⅳstagefrom February 2013 to February 2014 in Anyang Eye Hospital admitted in fundus disease department. The health control(HCgroup of 55 normal people was established simultaneously. Ocular blood flow velocity of the 55 normal people(110 eyesand the 60 patients(120 eyeswas examined by CDFI of central retinal artery(CRAand posterior ciliary artery(PCAsusing the PHILIPS HD6. Peak systolic velocity(PSVwas recorded. The examinations of CDFI, electroretinogram(ERGand the vision were performed in pre-operation, 1,7d, 1, 3 and 6mo postoperatively. RESULTS: Compared the PSV of CRA of the DR group before and after photocoagulation to the data of the HC group, there was a significant difference(PPPPP>0.05. Compared the aA and bA of ERG of the DR group before and after photocoagulation to the data of the HC group, there was a significant difference(PPP>0.05. The vision of 49 cases(98 eyeswas improved 1 to 3 rows, the effective rate was 82%.The vision of 11 cases(22 eyesremained constant.CONCLUSION: Retinal laser photocoagulation is an effective treatment to diabetic retinopathy patients, which can significantly reduce the peak systolic velocity of the central retinal artery, improve and stabilize the condition, protect visual function in long-term clinical effect. Color doppler flow imaging can observe the changes of ocular vessel flow velocity in diabetic' eyes noninvasively, repeatedly and in real time, providing a basis for clinical treatments.

  13. Recurrent twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a systematic review of the literature.

    LENUS (Irish Health Repository)

    Walsh, C A

    2012-11-01

    Selective fetoscopic laser photocoagulation (SFLP) is now the treatment of choice for twin-twin transfusion syndrome (TTTS). The incidence of recurrent TTTS following SFLP has been inconsistently reported across different studies. We performed a systematic review of TTTS recurrence following SFLP.

  14. Intravitreal ranibizumab and laser photocoagulation in the management of idiopathic juxtafoveolar retinal telangiectasia type 1: a case report.

    Science.gov (United States)

    Ciarnella, Angela; Verrilli, Sara; Fenicia, Vito; Mannino, Cristina; Cutini, Alessandro; Perdicchi, Andrea; Recupero, Santi Maria

    2012-09-01

    Idiopathic juxtafoveolar retinal telangiectasia (IJRT) type 1 represents an uncommon cause of congenital unilateral visual loss and it typically affects males. Decrease in visual acuity is caused by serous and lipid exudation into the fovea with cystoid macular edema. In some cases, spontaneous resolution may be observed, but when there is a progressive loss of visual acuity, laser photocoagulation is often necessary. This treatment is not always successful and therapy for this condition is still controversial. A 57-year-old man referred a 2-month history of blurred and distorted vision in the right eye. Best-corrected visual acuity was 20/50 in the right eye and 20/20 in the left eye. Fundus examination showed temporal macular edema, confirmed by optical coherence tomography. Fluorescein angiography showed a localized area of hyperfluorescence probably due to telangiectasia type 1 located below the inferior temporal area of the fovea. A combined therapy of intravitreal ranibizumab injection and laser photocoagulation was performed. Visual acuity improved from 20/50 to 20/32 and the therapy was well tolerated by the patient. After 3 years of follow-up, both visual acuity and fundus examination were stable. This case suggests that the combined use of ranibizumab and laser photocoagulation may be considered an effective treatment for JRT type 1, leading to an improvement in both visual acuity and macular edema. We believe that intravitreal ranibizumab injection associated with laser photocoagulation should be considered as treatment for IJRT type 1.

  15. [Efficacy of topical ketorolac for improving visual function after photocoagulation in diabetic patients with focal macular edema].

    Science.gov (United States)

    Razo Blanco-Hernández, Dulce Milagros; Lima-Gómez, Virgilio; Asbun-Bojalil, Juan

    2014-01-01

    Photocoagulation reduces the incidence of visual loss in diabetic patients with focal macular edema, but it can induce it for Efficacy of topical ketorolac for improving visual function after photocoagulation in diabetic patients with focal macular edema 6 weeks after treatment and produces visual improvement in some cases. Topical ketorolac may reduce the inflammation caused by photocoagulation and improve visual outcome. To determine the efficacy of topical ketorolac for improving visual function after photocoagulation in diabetic patients with focal macular edema. An experimental, comparative, prospective, longitudinal study in diabetic patients with focal macular edema was conducted. Eyes were randomized into two groups of topical treatment for 3 weeks after photocoagulation (A: ketorolac, B: placebo). Best corrected visual acuity before and after treatment was compared in each group (paired t test), and the proportion of eyes with visual improvement was compared between groups (χ(2)). The evaluation was repeated after stratifying for initial visual acuity (≥ 0.5, visual acuity changed from 0.50 to 0.58 (p= 0.003), and from 0.55 to 0.55 in group B (n= 59, p= 0.83); mean percent change was 22.3% in group A and 3.5% in group B (p= 0.03). Visual improvement was identified in 25 eyes from group A (54.3%) and 19 from group B (32.2%, p= 0.019, RR 1.65); the difference only persisted when initial visual acuity was ≥ 0.5 (10 [40%], group A, 5 [14.7%], group B, p= 0.02, RR 2.72). Topical ketorolac was more effective than placebo to improve best corrected visual acuity in diabetic patients with focal macular edema.

  16. Peripapillary RNFL Thickness Changes after Panretinal Photocoagulation.

    Science.gov (United States)

    Yazdani, Shahin; Samadi, Poorya; Pakravan, Mohammad; Esfandiari, Hamed; Ghahari, Elham; Nourinia, Ramin

    2016-09-01

    To evaluate changes in peripapillary retinal nerve fiber layer (RNFL) thickness as determined by spectral domain optical coherence tomography (SD-OCT) after panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR). Forty-two eyes of 42 diabetic patients who were scheduled for PRP were enrolled in this interventional case series. Peripapillary RNFL thickness was measured using SD-OCT (OCT 1000; Topcon Co., Tokyo, Japan) at baseline and 1, 3, and 6 months after PRP. Mean global RNFL thickness was increased significantly by 3 μm (p = 0.04) 1 month after PRP and was then decreased marginally significantly by 2.4 μm at 6 months (p = 0.054) as compared to baseline values. After 1 month, RNFL thickness was increased in all quadrants, but only changes in the temporal quadrant were significant (p = 0.009). At 6 months, progressive RNFL thinning occurred in all quadrants; however, only changes in the superior quadrant were significant (p = 0.041). Visual acuity was improved by an average of 0.02 logMAR after 6 months, but this change was not statistically significant. Shortly after PRP, RNFL thickness (as determined by SD-OCT) increases, but a decrease in RNFL thickness occurs at 6 months post-PRP. RNFL thickness changes based on OCT should be interpreted with caution in diabetic eyes undergoing PRP.

  17. Development of transrectal diffuse optical tomography combined with 3D-transrectal ultrasound imaging to monitor the photocoagulation front during interstitial photothermal therapy of primary focal prostate cancer

    Science.gov (United States)

    He, Jie; Weersink, Robert; Veilleux, Israel; Mayo, Kenwrick; Zhang, Anqi; Piao, Daqing; Alam, Adeel; Trachtenberg, John; Wilson, Brian C.

    2013-03-01

    Interstitial near-infrared laser thermal therapy (LITT) is currently undergoing clinical trials as an alternative to watchful waiting or radical surgery in patients with low-risk focal prostate cancer. Currently, we use magnetic resonance image (MRI)-based thermography to monitor treatment delivery and determine indirectly the completeness of the target tissue destruction while avoiding damage to adjacent normal tissues, particularly the rectal wall. However, incomplete tumor destruction has occurred in a significant fraction of patients due to premature termination of treatment, since the photocoagulation zone is not directly observed. Hence, we are developing transrectal diffuse optical tomography (TRDOT), in combination with transrectal 3D ultrasound (3D-TRUS), to address his limitation. This is based on the large changes in optical scattering expected upon tissue coagulation. Here, we present forward simulations of a growing coagulated lesion with optical scattering contrast, using an established finite element analysis software platform (NIRFAST). The simulations were validated in tissue-simulating phantoms, with measurements acquired by a state-of-the-art continuous wave (CW) TRDOT system and a recently assembled bench-top CW-DOT system, with specific source-detector configurations. Two image reconstruction schemes were investigated and evaluated, specifically for the accurate delineation of the posterior boundary of the coagulation zone as the critical parameter for treatment guidance in this clinical application.

  18. Dynamics of pulsed holmium:YAG laser photocoagulation of albumen

    Energy Technology Data Exchange (ETDEWEB)

    Pfefer, T.J. [Biomedical Engineering Program, The University of Texas at Austin, Austin, TX 78712 (United States). E-mail: jpfefer at helix.mgh.harvard.edu; Chan, K.F.; Hammer, D.X. [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Welch, A.J. [Biomedical Engineering Program, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712 (United States)

    2000-05-01

    The pulsed holmium:YAG laser ({lambda} = 2.12 {mu}m, {tau}{sub p} = 250 {mu}s) has been investigated as a method for inducing localized coagulation for medical procedures, yet the dynamics of this process are not well understood. In this study, photocoagulation of albumen (egg white) was analysed experimentally and results compared with optical-thermal simulations to investigate a rate process approach to thermal damage and the role of heat conduction and dynamic changes in absorption. The coagulation threshold was determined using probit analysis, and coagulum dynamics were documented with fast flash photography. The nonlinear computational model, which included a Beer's law optical component, a finite difference heat transfer component and an Arrhenius equation-based damage calculation, was verified against data from the literature. Moderate discrepancies between simulation results and our experimental data probably resulted from the use of a laser beam with an irregular spatial profile. This profile produced a lower than expected coagulation threshold and an irregular damage distribution within a millisecond after laser onset. After 1 ms, heat conduction led to smoothing of the coagulum. Simulations indicated that dynamic changes in absorption led to a reduction in surface temperatures. The Arrhenius equation was shown to be effective for simulating transient albumen coagulation during pulsed holmium:YAG laser irradiation. Greater understanding of pulsed laser-tissue interactions may lead to improved treatment outcome and optimization of laser parameters for a variety of medical procedures. (author)

  19. Rubber band ligation and infrared photocoagulation for the outpatient treatment of hemorrhoidal disease Ligadura elástica e fotocoagulação com radiação infravermelha no tratamento ambulatorial da doença hemorroidária

    Directory of Open Access Journals (Sweden)

    Maurício Pichler Ricci

    2008-02-01

    Full Text Available PURPOSE: To compare the results of rubber band ligation and infrared photocoagulation for the treatment of hemorrhoidal disease through the analysis of the incidence of complications after each treatment and respective success rate. METHODS: Forty-eight patients with first, second or third degree hemorrhoidal disease were randomized to recieve treatment with either rubber band ligation (n=23 or infrared photocoagulation (n=25. Each patient was assessed at 1 week and 4 week intervals after treatment. We compared the incidence of complications and efficiency of each treatment modality and Qui-square, Fisher's Exact Test and Student's t Test were used to statistical analysis. RESULTS: Bleeding occured in eigth (34,7% patients treated with rubber band ligation and in four (16,0% after infrared photocoagulation (p=0,243. Thirteen (52,0% patients felt pain during infrared photocoagulation and 9 (39,1% after rubber band ligation (p=0,546. After rubber band ligation, 14 (60,8% required medication for pain relief. One patient (4,0% required medication after infrared photocoagulation (pOBJETIVO: Comparar os resultados da ligadura elástica com os da fotocoagulação com radiação infravermelha no tratamento da doença hemorroidária através da análise de suas respectivas morbidades e eficácia. MÉTODOS: Foi realizado ensaio clínico casualisado com 48 pacientes portadores de doença hemorroidária graus I, II e III. Após randomização, os pacientes foram submetidos à ligadura elástica (n=23 ou fotocoagulação com radiação infravermelha (n=25. Os pacientes compareceram para consulta ambulatorial 1 semana e 4 semanas após o procedimento. A avaliação foi feita através da análise da incidência de morbidades após cada procedimento e eficácia, com quatro semanas de acompanhamento. As análises estatísticas foram realizadas através do teste do Qui-quadrado, Teste Exato de Fisher e Teste t de Student. RESULTADOS: Dos pacientes submetidos

  20. [Photocoagulation guided by fundus camera (new photocoagulation method of the retina with a non-contact and wide field system)].

    Science.gov (United States)

    Fernández-Vigo, J; Macarro, A; Viguera, F J; Calles, C; Usón, J

    2002-10-01

    To design a device that integrates a laser photocoagulator in a fundus camera so that the functions of both are incorporated for their simultaneous use. This system would allow the visualizacion of the fundus during photocoagulation, with a no-contact, no hand-helped lens technique. To test the device we used a fundus camera Fx500 (Kowa) and a diode laser Oculight SLx (Iris Medical). We analysed the physical and power laser parameters, performing a comprehensive control of the device's safety. In order to measure the error in the precision of the laser, we designed a micrometric test to evaluate the directionality of the beam and the focusing system. Finally, we test the size, time of exposure and intensity necessary to obtain an effective impact. With our system, transpupilar photocoagulation fullfils the main safety requirements on laser radiation and illumination in retinoscopy. After diverse adjustments, the laser impacts were placed in the desired retinal areas. The lesions generated in the pig eyes were quite similar to those obtained by conventional techniques and they were time and intensity dependent. Photocoagulation with our sytem is very simple and potentially safe and effective. It may facilitate the photocoagulation process inasmuch as it is more comfortable and user-friendly.

  1. Grid pattern Argon Laser photocoagulation for diabetic diffuse macular edema

    Directory of Open Access Journals (Sweden)

    Karkhane R

    1998-05-01

    Full Text Available Purpose: to determine the effect of Grid pattern laser photocoagulation on diabetic diffuse macular edema with assessment of visual outcome. Patients & Methods: The author reviewed the medical records of 84 eyes of 62 patients with diabetic diffuse macular edema treated with Grid pattern green Argon laser photocoagulation in Farabi Eye Hospital between the years 1992-1995, the follow-up period was 16-48 months (average 24.55±6.42, median 28 mounths. Results: Visual acuity was improved in 11.9%; unchanged in 65.4% and worsened in 22.7% of eyes. Conclusion: In assessing long-term visual outcome, Grid laser photocoagulation is an effective modality in maintaining or improving visual acuity.

  2. Observation of clinical efficacy of pattern scan laser photocoagulation on diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Zhi-Hua Peng

    2013-08-01

    Full Text Available AIM: To evaluate the clinical efficacy of pattern scan laser photocoagulation(Pascalon proliferative diabetic retinopathy(PDR.METHODS: A total of 93 patients with retinopathy(186 eyeswere randomly divided into treatment group(96 eyes of 48 patientswho treated with panretinal photocoagulation(PRPusing Pascal at one time and control group(90 eyes of 45 patientswho treated with PRP using multi-wavelength krypton laser in 4-5 times. The visual acuity, FFA, OCT, visual field will be evaluated of each patient before and after the treatment.RESULTS: The visual acuity findings were stated as below: the overall effective rate of visual acuity in treatment group is 85.4% while it is 82.2% in control group. The overall effective rate in two groups has no significant difference. The retinal sensitivity has no significant decrease in the treatment group while which decreased significantly in the control group.CONCLUSION: The clinical efficacy of Pascal on treating the PDR is better than which of the regular argon laser. The field of vision has no significant narrowed after the Pascal treatment which can efficiently shorten the length of treatment and reduce the pain sensation.

  3. Fetoscopic laser photocoagulation for twin-twin transfusion syndrome.

    Science.gov (United States)

    Sago, Haruhiko; Ishii, Keisuke; Sugibayashi, Rika; Ozawa, Katsusuke; Sumie, Masahiro; Wada, Seiji

    2018-02-13

    The aim of this study was to review fetoscopic laser photocoagulation (FLP), which ablates placental vascular anastomoses to treat twin-twin transfusion syndrome (TTTS). A review of studies reporting on the procedures, outcomes, complications and nonconventional applications of FLP for TTTS was conducted. FLP has been established as the primary treatment for monochorionic twin pregnancy associated with TTTS at 16-26 weeks. FLP is the only therapy that directly addresses the underlying pathophysiology. The recent technique modification of FLP, referred to as the 'Solomon technique', induces selective coagulation to connect the anastomoses ablation sites and has been introduced to reduce residual anastomoses. The perinatal survival following FLP improved significantly with advances in the technique after its introduction. The recent survival rates of both twins and at least one twin are 70% and more than 90%, respectively. However, there is still an 11-14% risk of long-term neurodevelopment impairment. The premature rupture of membranes that leads to preterm labor is a common complication after FLP. FLP is a valuable treatment option for feto-fetal transfusion syndrome in triplets and for TTTS after 26 weeks. FLP for selective intrauterine growth restriction may be potentially beneficial when accompanied by abnormal Doppler findings and oligohydramnios. FLP is the optimal treatment option for TTTS at 16-26 weeks of gestation. FLP appears to be applicable in triplets, TTTS after 26 weeks and cases of selective intrauterine growth restriction with abnormal Doppler findings and oligohydramnios. FLP is the most common and successful fetal intervention. Improvement in the neurodevelopmental outcomes after FLP is a future focus. © 2018 Japan Society of Obstetrics and Gynecology.

  4. Factors affecting reading speed in patients with diabetic macular edema treated with laser photocoagulation.

    Directory of Open Access Journals (Sweden)

    Elizabeth Pearce

    Full Text Available PURPOSE: To study the factors that may affect reading speed in patients with diabetic macular edema previously treated with laser photocoagulation. METHODS: Consecutive patients with type II diabetes treated with laser photocoagulation for diabetic macular edema (DME at least twelve months previously, with best corrected visual acuity of better than 65 letters (approximately 20/40 measured with Early Treatment Diabetic Retinopathy Study (ETDRS charts were included in this study. Patients previously treated with pan-retinal photocoagulation, vitrectomy, intravitreal steroid or anti-VEGF therapy were excluded. Any other ocular co-morbidities that may influence reading ability such as cataract, glaucoma or macular degeneration were also excluded. All patients were refracted by a certified examiner, the following measurements were collected: best corrected visual acuity (BCVA, contrast sensitivity with Pelli-Robson chart, reading speed with MNREAD chart, microperimetry with Nidek MP1, and central subfield thickness with Zeiss spectral domain optical coherent topography. RESULTS: The slow reading group had poorer contrast sensitivity (p = 0.001, reduced retinal sensitivity (p = 0.027 and less stable fixation (p = 0.013. Most interestingly the reduced retinal sensitivity findings were driven by the microperimetry value on the right subfield (p = 0.033, (nasal to the fovea in the right eye and temporal to the fovea in the left eye. Multiple linear regression analysis showed that contrast sensitivity is probably the most important factor that affects reading speed (p = 0.001. CONCLUSION: Reduced retinal sensitivity after laser treatment is associated with reduced reading speed in patients with diabetic macular edema.

  5. Factors affecting reading speed in patients with diabetic macular edema treated with laser photocoagulation.

    Science.gov (United States)

    Pearce, Elizabeth; Sivaprasad, Sobha; Chong, Ngaihang V

    2014-01-01

    To study the factors that may affect reading speed in patients with diabetic macular edema previously treated with laser photocoagulation. Consecutive patients with type II diabetes treated with laser photocoagulation for diabetic macular edema (DME) at least twelve months previously, with best corrected visual acuity of better than 65 letters (approximately 20/40) measured with Early Treatment Diabetic Retinopathy Study (ETDRS) charts were included in this study. Patients previously treated with pan-retinal photocoagulation, vitrectomy, intravitreal steroid or anti-VEGF therapy were excluded. Any other ocular co-morbidities that may influence reading ability such as cataract, glaucoma or macular degeneration were also excluded. All patients were refracted by a certified examiner, the following measurements were collected: best corrected visual acuity (BCVA), contrast sensitivity with Pelli-Robson chart, reading speed with MNREAD chart, microperimetry with Nidek MP1, and central subfield thickness with Zeiss spectral domain optical coherent topography. The slow reading group had poorer contrast sensitivity (p = 0.001), reduced retinal sensitivity (p = 0.027) and less stable fixation (p = 0.013). Most interestingly the reduced retinal sensitivity findings were driven by the microperimetry value on the right subfield (p = 0.033), (nasal to the fovea in the right eye and temporal to the fovea in the left eye). Multiple linear regression analysis showed that contrast sensitivity is probably the most important factor that affects reading speed (p = 0.001). Reduced retinal sensitivity after laser treatment is associated with reduced reading speed in patients with diabetic macular edema.

  6. Efficacy of intravitreal ranibizumab injection combined with macular grid photocoagulation for diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Hu-Lin Jiang

    2014-07-01

    Full Text Available AIM:To evaluate the clinical efficacy of intravitreal injection of ranibizumab combined with macular grid photocoagulation for diabetic macular edema(DME.METHODS:Totally 60 eyes(60 patientswith DME were randomly divided into 2 groups: 30 eyes of simple injection group underwent intravitreal injection of ranibizumab, and 30 eyes of combined treatment group underwent intravitreal injection of ranibizumab and macular grid photocoagulation 1wk later. The best corrected visual acuity(BCVA, central macular thickness(CMTmeasured by optical coherence tomography(OCTand postoperative complications were observed.RESULTS:In simple injection group, the BCVA after operation were separately 0.390±0.075(4wk, 0.367±0.088(8wkand 0.319±0.064(12wk,the CMT after operation were separately 221.63±112.34μm(4wk, 337.73±99.56μm(8wkand 432.92±100.46μm(12wk, which were much better than pre-operation. But during follow-up, the BCVA presented down trend and the CMT was on the rise slowly. In combined treatment group, the BCVA after operation were separately 0.385±0.036(4wk, 0.382±0.079(8wkand 0.377±0.097(12wk,the CMT after operation were separately 249.77±106.55μm(4wk, 270.40±92.88μm(8wkand 275.84±97.34μm(12wk, which were satisfactory and steady during follow-up, better than simple injection group(PCONCLUSION:Intravitreal injection of ranibizumab can effectively improve visual acuity and decrease central foveal thickness for patients with DME, combining with macular grid photocoagulation can ensure therapeutic effects steady and permanent.

  7. Visual Outcome after Laser Photocoagulation for Stage 4 ...

    African Journals Online (AJOL)

    Objective: The objectives of this research is to evaluate the visual outcome after peripheral laser photo-coagulation for Goldberg stage-4 proliferative sickle cell retinopathy patients seen in Eye Foundation Hospital Lagos between January and December 2002. Methodology: A hospital-based retrospective case review study ...

  8. The evaluation of efficacy of subtenon triamcinolone injection combined with focal laser photocoagulation in diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Hüseyin Öksüz

    2012-06-01

    Full Text Available Objectives: The aim of this study was to investigate efficacyand safety of subtenon triamcinolone (ST in combinationwith focal laser photocoagulation in diabetic macularedema (DME.Materials and methods: Medical records of patients withDME, treated with 40 mg subtenon injection of triamcinoloneacetonid prior to focal laser photocoagulation wereretrospectively analyzed. Seventeen eyes of 17 patientswith DME were enrolled in the study. All patients underwenta comprehensive ophthalmological examinationbefore the treatment. Efficacy of the treatment after STinjection was evaluated by visual acuity and flouresceinangiography (FA. Follow-up visits were performed at 1st,3rd, 6th and 12th months. Repeated measures ANOVA wasused for statistical analysis.Results: The mean age was 61.5 ± 8.7 years and themean visual acuity in the study eyes was 0.22 ± 0.13 beforethe treatment, 0.39 ± 0.15 at 1st month, 0.36 ± 0.18at 3rd month, 0.33 ± 0.15 at 6th month and 0.34 ± 0.16 at12th month. The differences in the visual acuity before thetreatment and follow-up visits were significant (p ˂0.05.Visual acuity was increased in 13 (%76,4 patients, decreasedin 1 (%5,8 and unchanged in 3 (%17,6.Conclusion: Injection of 40 mg of triamsinolon via subtenonroute combined with focal laser photocoagulation isa safe and beneficial treatment in cases of DME

  9. Quantum Theory of (H,H{Sub 2}) Scattering: Approximate Treatments of Reactive Scattering

    Science.gov (United States)

    Tang, K. T.; Karplus, M.

    1970-10-01

    A quantum mechanical study is made of reactive scattering in the (H, H{sub 2}) system. The problem is formulated in terms of a form of the distorted-wave Born approximation (DWBA) suitable for collisions in which all particles have finite mass. For certain incident energies, differential and total cross sections, as well as other attributes of the reactive collisions, (e.g. reaction configuration), are determined. Two limiting models in the DWBA formulation are compared; in one, the molecule is unperturbed by the incoming atom and in the other, the molecule adiabatically follows the incoming atom. For thermal incident energies and semi-empirical interaction potential employed, the adiabatic model seems to be more appropriate. Since the DWBA method is too complicated for a general study of the (H, H{sub 2}) reaction, a much simpler approximation method, the “linear model” is developed. This model is very different in concept from treatments in which the three atoms are constrained to move on a line throughout the collision. The present model includes the full three-dimensional aspect of the collision and it is only the evaluation of the transition matrix element itself that is simplified. It is found that the linear model, when appropriately normalized, gives results in good agreement with that of the DWBA method. By application of this model, the energy dependence, rotational state of dependence and other properties of the total and differential reactions cross sections are determined. These results of the quantum mechanical treatment are compared with the classical calculation for the same potential surface. The most important result is that, in agreement with the classical treatment, the differential cross sections are strongly backward peaked at low energies and shifts in the forward direction as the energy increases. Finally, the implications of the present calculations for a theory of chemical kinetics are discussed.

  10. Comparison of pain scores between patients undergoing panretinal photocoagulation using navigated or pattern scan laser systems

    Directory of Open Access Journals (Sweden)

    Umit Ubeyt Inan

    2016-02-01

    Full Text Available ABSTRACT Purpose: To compare the pain responses of patients with proliferative diabetic retinopathy (PDR undergoing panretinal photocoagulation (PRP using either pattern scan laser (PASCAL or navigated laser photocoagulation (NAVILAS. Methods: Patients diagnosed with PDR were randomly assigned to undergo either PASCAL or NAVILAS photocoagulation treatment. PRP was performed using the multi-shot mode with a spot size of 200-400 µm and a pulse duration of 30 ms to obtain a white-grayish spot on the retina. Parameters were identical in both procedures. After 30 min of PRP application, patients were asked to verbally describe their pain perception as either "none," "mild," "moderate," "severe," or "very severe" using a verbal rating scale (VRS and visual analog scale (VAS by indicating a score from "0" to "10," representing the severity of pain from "no pain" to "severe pain." Results: A total of 60 eyes of 60 patients (20 females and 40 males diagnosed with PDR were treated. The mean age of patients was 62.22 ± 9.19 years, and the mean diabetes duration was 195.47 ± 94.54 months. The mean number of laser spots delivered during PRP was 389.47 ± 71.52 in the NAVILAS group and 392.70 ± 54.33 in the PASCAL group (p=0.57. The difference in pain responses between patients in the NAVILAS and PASCAL groups was significant with regard to the mean VRS (1.10 ± 0.67 and 1.47 ± 0.69, respectively; p=0.042 and mean VAS (2.13 ± 1.17 and 2.97 ± 1.35, respectively; p=0.034 scores. Conclusions: Pain responses in patients undergoing PRP with a 30-ms pulse duration were significantly milder in the NAVILAS group than in the PASCAL group.

  11. Intravitreal Ranibizumab and Laser Photocoagulation in the Management of Idiopathic Juxtafoveolar Retinal Telangiectasia Type 1: A Case Report

    Directory of Open Access Journals (Sweden)

    Angela Ciarnella

    2012-09-01

    Full Text Available Background: Idiopathic juxtafoveolar retinal telangiectasia (IJRT type 1 represents an uncommon cause of congenital unilateral visual loss and it typically affects males. Decrease in visual acuity is caused by serous and lipid exudation into the fovea with cystoid macular edema. In some cases, spontaneous resolution may be observed, but when there is a progressive loss of visual acuity, laser photocoagulation is often necessary. This treatment is not always successful and therapy for this condition is still controversial. Case Presentation: A 57-year-old man referred a 2-month history of blurred and distorted vision in the right eye. Best-corrected visual acuity was 20/50 in the right eye and 20/20 in the left eye. Fundus examination showed temporal macular edema, confirmed by optical coherence tomography. Fluorescein angiography showed a localized area of hyperfluorescence probably due to telangiectasia type 1 located below the inferior temporal area of the fovea. A combined therapy of intravitreal ranibizumab injection and laser photocoagulation was performed. Visual acuity improved from 20/50 to 20/32 and the therapy was well tolerated by the patient. After 3 years of follow-up, both visual acuity and fundus examination were stable. Conclusions: This case suggests that the combined use of ranibizumab and laser photocoagulation may be considered an effective treatment for JRT type 1, leading to an improvement in both visual acuity and macular edema. We believe that intravitreal ranibizumab injection associated with laser photocoagulation should be considered as treatment for IJRT type 1.

  12. Aniridia Associated with Lens Coloboma and Secondary Glaucoma Treated with Transcorneal Argon Laser Ciliary Body Photocoagulation: A Case Report

    Directory of Open Access Journals (Sweden)

    Sandro Sbordone

    2013-06-01

    Full Text Available Purpose: The aim of this study is to describe the management of cataract and refractory glaucoma in a case of congenital aniridia (AN-1. Methods: In an 18-year-old female patient affected by congenital AN, bilateral coloboma of the zonula and lens, cataract and glaucoma, pars plana vitrectomy, cataract extraction and subsequent transcorneal ciliary body argon laser photocoagulation were performed. Results: Five years after laser treatment, the best-corrected visual acuity was 20/50 and the intraocular pressure was stable at 18 mm Hg with topical pharmacological management consisting of timolol 0.5% and latanoprost 0.005%. Conclusions: From our experience, transcorneal ciliary body photocoagulation after cataract extraction and vitrectomy could be a useful technique to manage high ocular pressure in eyes affected by congenital AN.

  13. Resolution of pinguecula-related dry eye disease after argon laser photocoagulation

    Directory of Open Access Journals (Sweden)

    Napoli PE

    2017-07-01

    Full Text Available Pietro Emanuele Napoli,1 Raffaele Sanna,1 Claudio Iovino,1 Maurizio Fossarello,1,2 1Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy; 2Clinica Oculistica, San Giovanni di Dio hospital, Azienda Ospedaliera Universitaria di Cagliari, Cagliari, Italy Purpose: To describe an unusual case of unilateral, chronic symptoms and signs of dry eye, and recurrent episodes of ocular irritation related to pinguecula, which were refractory to prior medical treatments, successfully treated with argon laser photocoagulation.Methods: A 36-year-old man presented with an elevated yellowish mass on his conjunctiva in his left eye, which was associated with dry eye symptoms and general discomfort, such as “tightening sensation” and “stiffness”. On clinical assessment, the left eye revealed a mild conjunctival injection, a fluorescein break-up time (FBUT of 3.5 s, an abnormal fluorescein staining, and a Schirmer I test of 5 mm. Optical coherence tomography (OCT imaging ­evidenced a height at the most elevated point of the pinguecula of 740 µm. The patient underwent ­argon-laser photocoagulation. Results: After 2 weeks postoperatively, no residual of pinguecula or focal injection of the conjunctiva was detected by slit-lamp biomicroscopy and there was a significant improvement of clinical symptoms and signs: Schirmer I test and FBUT increased to 12 mm and >10 s, respectively, and fluorescein staining was absent. OCT imaging revealed a smooth structure of conjunctival contour, with a height of 404 µm. According to an ex juvantibus line of reasoning, definitive diagnosis was pinguecula-related dry eye disease.Conclusion: Based on the concept that tear film instability and inflammation are two key components of the pathogenesis of dry eye, we coined the term “pinguecula-related dry eye disease,” which can be successfully treated by a complete, accurate removal of the lesion with argon laser photocoagulation. Keywords

  14. Posterior Pole Sparing Laser Photocoagulation Combined with Intravitreal Bevacizumab Injection in Posterior Retinopathy of Prematurity

    Directory of Open Access Journals (Sweden)

    Rebecca Kim

    2014-01-01

    Full Text Available Purpose. To report the results of the posterior pole sparing laser photocoagulation combined with intravitreal bevacizumab injection (IVB in retinopathy of prematurity (ROP. Methods. A retrospective chart review of premature babies with ROP, all of whom received laser photocoagulation with IVB. Eleven eyes of 6 infants with advanced zone I ROP underwent laser ablation sparing posterior pole with concurrent IVB. The results were compared with those of full-laser treatment combined with IVB to 8 eyes of 5 infants with advanced ROP without involvement of the posterior pole. Results. The posterior pole sparing laser with IVB was performed with zone I, stage 3+ ROP at the mean postmenstrual age of 36 weeks and 5 days. The plus sign decreased significantly at postoperative day 1, the neovascular proliferation regressed by postoperative week 1, and the normal vascularization started at postoperative day 32 on the average. Two months after treatment, vascularization of the spared avascular area was completed. There was no macular dragging, tractional retinal detachment, foveal destruction by laser scars, or any other adverse event. No significant anatomical differences were identified from those of full-laser ablation combined with IVB. Conclusions. Posterior pole sparing laser with IVB can give favorable results without destruction of posterior pole retina.

  15. A Computational Model of Peripheral Photocoagulation for the Prevention of Progressive Diabetic Capillary Occlusion

    Directory of Open Access Journals (Sweden)

    Thomas J. Gast

    2016-01-01

    Full Text Available We developed a computational model of the propagation of retinal ischemia in diabetic retinopathy and analyzed the consequences of various patterns and sizes of burns in peripheral retinal photocoagulation. The model addresses retinal ischemia as a phenomenon of adverse local feedback in which once a capillary is occluded there is an elevated probability of occlusion of adjacent capillaries resulting in enlarging areas of retinal ischemia as is commonly seen clinically. Retinal burns of different sizes and patterns, treated as local oxygen sources, are predicted to have different effects on the propagation of retinal ischemia. The patterns of retinal burns are optimized with regard to minimization of the sum of the photocoagulated retina and computer predicted ischemic retina. Our simulations show that certain patterns of retinal burns are effective at preventing the spatial spread of ischemia by creating oxygenated boundaries across which the ischemia does not propagate. This model makes no statement about current PRP treatment of avascular peripheral retina and notes that the usual spot sizes used in PRP will not prevent ischemic propagation in still vascularized retinal areas. The model seems to show that a properly patterned laser treatment of still vascularized peripheral retina may be able to prevent or at least constrain the propagation of diabetic retinal ischemia in those retinal areas with intact capillaries.

  16. Management of peripheral polypoidal choroidal vasculopathy with intravitreal bevacizumab and indocyanine green angiography-guided laser photocoagulation

    Directory of Open Access Journals (Sweden)

    Pukhraj Rishi

    2012-01-01

    Full Text Available A 69-year-old lady presented with complaints of decreased vision in left eye since one month. Best Corrected Visual Acuity (BCVA was 6/18 in that eye. Fundus examination revealed non-central geographic atrophy and soft drusens at macula in both eyes. Temporal periphery of left eye revealed subretinal exudates with altered sub-RPE hemorrhage mimicking peripheral exudative hemorrhagic chorioretinopathy (PEHCR. Fundus Fluorescein Angiogram showed window defects at macula and blocked fluorescence at temporal periphery in left eye. However, Indocyanine green angiography (ICGA revealed active peripheral choroidal polyps. The patient was successfully treated with intravitreal bevacizumab and ICGA-guided laser photocoagulation. 27 months after laser treatment, BCVA improved to 6/9. Rationale of consecutive anti-vascular endothelial growth factor (VEGF treatment followed by more definitive laser photocoagulation is that anti-VEGF aids in resolution of subretinal fluid, thus making the polyp more amenable to focal laser photocoagulation which stabilizes the choroidal vasculature and prevents further leakage.

  17. Clinical effects and safety of treating diabetic macular edema with intravitreal injection of ranibizumab combined with retinal photocoagulation

    Directory of Open Access Journals (Sweden)

    Yan PS

    2016-04-01

    Full Text Available Panshi Yan, Cheng Qian, Wenzhan Wang, Yi Dong, Guangming Wan, Yue Chen Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China Background: This study was designed to examine the clinical effects of treating diabetic macular edema with an intravitreal injection of ranibizumab in combination with retinal photocoagulation.Methods: Sixty-two cases (75 eyes with confirmed severe proliferative diabetic retinopathy or proliferative diabetic retinopathy in combination with macular edema were randomly divided into the observation group (37 eyes were given an intravitreal injection of ranibizumab combined with retinal photocoagulation and the control group (38 eyes received retinal photocoagulation only. Vision, fundus condition, central macular thickness, and the macular leakage area were recorded before and after treatment.Results: The best-corrected visual acuity and macular leakage area were similar between the observation and control groups (P>0.05. The best-corrected visual acuity in the observation group was higher than that in the control group 3 and 6 months after treatment (P<0.05 and showed a rising tendency. The macular leakage area in the observation group was significantly lower than that in the control group 1 and 3 months after treatment (P<0.05. However, the macular leakage area was similar 6 months after treatment (P>0.05. The central macular thickness of the observation group was lower than that in the control group 1, 3, and 6 months after treatment (P<0.05. The laser energy used in the observation group was also smaller than that in the control group (P<0.05. The intraocular pressure was not significantly different between the groups (P<0.05. No patients in the two groups developed eye or systemic complications, such as glaucoma, cataract, or vitreous hemorrhage during treatment. Conclusion: Intravitreal injection of ranibizumab combined with retinal photocoagulation

  18. Pilot study about dose-effect relationship of ocular injury in argon laser photocoagulation

    Science.gov (United States)

    Chen, P.; Zhang, C. P.; Fu, X. B.; Zhang, T. M.; Wang, C. Z.; Qian, H. W.; San, Q.

    2011-03-01

    The aim of this article was to study the injury effect of either convergent or parallel argon laser beam on rabbit retina, get the dose-effect relationship for the two types of laser beams, and calculate the damage threshold of argon laser for human retinas. An argon laser therapeutic instrument for ophthalmology was used in this study. A total of 80 rabbit eyes were irradiated for 600 lesions, half of which were treated by convergent laser and the other half were done with parallel laser beam. After irradiation, slit lamp microscope and fundus photography were used to observe the lesions, change and the incidence of injury was processed statistically to get the damage threshold of rabbit retina. Based on results from the experiments on animals and the data from clinical cases of laser treatment, the photocoagulation damage thresholds of human retinas for convergent and parallel argon laser were calculated to be 0.464 and 0.285 mJ respectively. These data provided biological reference for safely operation when employing laser photocoagulation in clinical practice and other fields.

  19. Laser photocoagulation around extra foveolar foci of toxoplasma retinochoroiditis: a way to decrease frequency of recurrence

    Science.gov (United States)

    Labalette, P.; Desmettre, Thomas; Mordon, Serge R.; Constantinides, G.

    1995-01-01

    Thirty four patients with retinochoroiditis initially treated with medical treatment and later treated with laser photocoagulation around the foci were retrospectively evaluated for the risk of recurrence of the eretinochoroiditis. We used a Kaplan-Meier representation to show the evolution of the number of patients without recurrence as a function of time and as the number of patients followed up decreases (rate of patients without recurrence at 1 year: 86 +/- 12.3% for 26 patients exposed; at 2 years: 75 +/- 16.4% for 20 patients exposed; at 3 years and at 4 years 70 +/- 17% for 17 patients exposed). The recurrence rates were compared to the data previously published in the literature. We failed to demonstrate the efficacy of laser photocoagulation on inactive retinochoroiditis for prevention of recurrence of ocular toxoplasmosis. However, the heterogeneity of our series, the great amount of patients lost to follow up, and the heterogeneity of the recurrence rates of the literature contribute to explain that result.

  20. Long-term outcomes of argon laser photocoagulation in small size cyclodialysis cleft.

    Science.gov (United States)

    Han, Jong Chul; Kwun, Young Kyo; Cho, Seok Ho; Kee, Changwon

    2015-09-24

    To evaluate the long-term outcomes of Argon laser photocoagulation compared to surgical direct cyclopexy in small-size cyclodialysis cleft patients. This is a retrospective study. Small-size cyclodialysis cleft patients who underwent Argon laser photocoagulation and surgical direct cyclopexy were reviewed. The mean follow-up period were 82.4 (range, 61 - 145) months and 99.9 (range, 62 - 184) months in both groups. The comparison of best corrected visual acuity (BCVA), intraocular pressure (IOP), postoperative peak IOP and time to normalization of IOP before and after the treatment. The causes of all included 15 cyclodialysis cleft cases were blunt trauma. seven patients underwent Argon laser photocoagulation and eight patients underwent surgical direct cyclopexy. The mean age of included patients was not significantly different (p = 0.38). Preoperatively, the mean logMAR BCVA (standard deviation, SD) was 0.7 (0.2) and 1.1 (0.9) and mean IOP was 4.4 (2.4) mmHg and 3.0 (1.5) mmHg in Argon laser group and surgical direct cyclopexy group (p = 0.24 and p = 0.18, respectively). The extension of cyclodialysis and duration of cyclodialysis cleft were not significantly different between the two groups (p = 0.08 and p = 0.24, respectively). The mean follow-up period were 82.4 (range, 61 - 145) months and 99.9 (range, 62 - 184) months in both groups (p = 0.41). Postoperatively, the mean logMAR BCVA was 0.0 (0.1) and 0.2 (0.3) and mean IOP was 14.5 (3.1) mmHg and 16.8 (2.5) mmHg (p = 0.15 and p = 0.16, respectively). Postoperative peak IOP and time to normalization of IOP were not different between the two groups (p = 0.75 and p = 0.91, respectively). It is necessary to use invasive treatment such as cryotherapy or surgical direct cyclopexy in cyclodialysis cleft with hypotonic maculopathy. In the present study, Argon laser photocoagulation showed good prognosis in a small-size cyclodialysis cleft below 1.5 clock-hours. Considering

  1. Resonance Elastic Scattering and Interference Effects Treatments in Subgroup Method

    Directory of Open Access Journals (Sweden)

    Yunzhao Li

    2016-04-01

    Full Text Available Based on the resonance integral (RI tables produced by the NJOY program, the conventional subgroup method usually ignores both the resonance elastic scattering and the resonance interference effects. In this paper, on one hand, to correct the resonance elastic scattering effect, RI tables are regenerated by using the Monte Carlo code, OpenMC, which employs the Doppler broadening rejection correction method for the resonance elastic scattering. On the other hand, a fast resonance interference factor method is proposed to efficiently handle the resonance interference effect. Encouraging conclusions have been indicated by the numerical results. (1 For a hot full power pressurized water reactor fuel pin-cell, an error of about +200 percent mille could be introduced by neglecting the resonance elastic scattering effect. By contrast, the approach employed in this paper can eliminate the error. (2 The fast resonance interference factor method possesses higher precision and higher efficiency than the conventional Bondarenko iteration method. Correspondingly, if the fast resonance interference factor method proposed in this paper is employed, the kinf can be improved by ∼100 percent mille with a speedup of about 4.56.

  2. A new treatment of nonlocality in scattering process

    Science.gov (United States)

    Upadhyay, N. J.; Bhagwat, A.; Jain, B. K.

    2018-01-01

    Nonlocality in the scattering potential leads to an integro-differential equation. In this equation nonlocality enters through an integral over the nonlocal potential kernel. The resulting Schrödinger equation is usually handled by approximating r,{r}{\\prime }-dependence of the nonlocal kernel. The present work proposes a novel method to solve the integro-differential equation. The method, using the mean value theorem of integral calculus, converts the nonhomogeneous term to a homogeneous term. The effective local potential in this equation turns out to be energy independent, but has relative angular momentum dependence. This method is accurate and valid for any form of nonlocality. As illustrative examples, the total and differential cross sections for neutron scattering off 12C, 56Fe and 100Mo nuclei are calculated with this method in the low energy region (up to 10 MeV) and are found to be in reasonable accord with the experiments.

  3. Interstitial laser photocoagulation in the treatment of liver tumors. Personal technique, short term results and complications in patients with normal and impaired liver function; Fotocoagulazione laser-interstiziale ecoguidata dei tumori maligni del fegato: tecnica personale, risultati immediati e complicanze a breve termine nei pazienti con funzionalita' epatica normale e alterata

    Energy Technology Data Exchange (ETDEWEB)

    Giorgio, A.; Tarantino, L.; De Stefano, G.; Farella, N. [Azienda Ospedaliera D. Cotugno, Naples (Italy). Servizio di Ecografia ed Ecointerventistica; Catalano, O.; Cusati, B. [Ospedale S. Maria delle Grazie, Pozzuoli, NA (Italy). Servizio di Radiologia; Alalia, A. [Azienda Ospedaliera D. Cotugno, Naples (Italy). Servizio di Anestesia e Rianimazione; Del Vescovo, L. [Naples Univ. II, Naples (Italy). Ist. di Radiologia

    2000-04-01

    The work reports the personal experience with interstitial laser photocoagulation in patients with liver tumors (mostly cirrhotics with hepatocellular carcinoma). The aim was to evaluate the short term efficacy of percutaneous interstitial laser photocoagulation in inducing focal ablation of liver tumors and the possible complications in patients with normal and impaired liver function. [Italian] Il presente lavoro riporta l'esperienza personale con l'utilizzazione della fotocoagulazione laser-interstiziale per tumori maligni del fegato, rappresentati in gran parte da epatocarcinomi in cirrosi. Lo scopo e' quello di verificare l'efficacia terapeutica in termini di volume di necrosi e di valutare gli effetti collaterali e le complicanze a breve termine sulla riserva funzionale del fegato e di altri organi, soprattutto nei pazienti con alterata funzionalita' epatica.

  4. Comparative effects of argon green and krypton red laser photocoagulation for patients with diabetic exudative maculopathy.

    Science.gov (United States)

    Khairallah, M; Brahim, R; Allagui, M; Chachia, N

    1996-01-01

    AIMS/BACKGROUND: Focal treatment of diabetic macular oedema is usually done using a haemoglobin absorbing wave-length, such as argon green laser. This study aimed to compare photocoagulation with argon green (514 nm) and krypton red (647 nm), which is poorly absorbed by haemoglobin, in the focal treatment of patients with diabetic exudative maculopathy. METHODS: A total of 151 eyes of 78 outpatients were assigned randomly to receive either argon green (n = 79) or krypton red (n = 72) laser treatment. Pretreatment and post-treatment ocular examinations included visual acuity, fundus biomicroscopic examination, and fluorescein angiography. A total of 141 eyes of 73 patients were available for evaluation after 1 year follow up. RESULTS: No statistically significant difference was found between the two treatment groups with respect to visual acuity results, resorption of hard exudates, and resolution of focal retinal oedema. CONCLUSION: Krypton red laser was effective in the treatment of diabetic exudative maculopathy. Our data suggest that differential absorption of the various wavelengths by haemoglobin within microaneurysms may not be an important factor for ultimate success of focal treatment. PMID:8703882

  5. Real-time optical coherence tomography observation of retinal tissue damage during laser photocoagulation therapy on ex-vivo porcine samples

    Science.gov (United States)

    Steiner, P.; Považay, B.; Stoller, M.; Morgenthaler, P.; Inniger, D.; Arnold, P.; Sznitman, R.; Meier, Ch.

    2015-07-01

    Retinal laser photocoagulation represents a widely used treatment for retinal pathologies such as diabetic chorioretinopathy or diabetic edema. For effective treatment, an appropriate choice of the treatment energy dose is crucial to prevent excessive tissue damage caused by over-irradiation of the retina. In this manuscript we investigate simultaneous and time-resolved optical coherence tomography for its applicability to provide feedback to the ophthalmologist about the introduced retinal damage during laser photocoagulation. Time-resolved and volumetric optical coherence tomography data of 96 lesions on ex-vivo porcine samples, set with a 577 nm laser prototype and irradiance of between 300 and 8800 W=cm2 were analyzed. Time-resolved scans were compared to volumetric scans of the lesion and correlated with ophthalmoscopic visibility. Lastly, image parameters extracted from optical coherence tomography Mscans, suitable for lesion classification were identified. Results presented in this work support the hypothesis that simultaneous optical coherence tomography provides valuable information about the extent of retinal tissue damage and may be used to guide retinal laser photocoagulation in the future.

  6. Effect of Ginkgo biloba on the lesions induced by retinal argon laser photocoagulation in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Clairambault, P.; Pairault, C.; Droy-Lefaix, M.T.; Magnier, B.; Magnier, M.

    1986-01-09

    In rabbits, retinal argon laser photocoagulation disrupts the arrangement of cell layers and produces interstitial edema. Photochemical and thermal energy is released with production of free oxygenated radicals that are responsible for destruction of cell membranes. Retinal argon laser photocoagulation in rabbits was used as a pharmacologic model to evaluate the protective effect of EGB 761 against membrane lesions and edema. As a strong free radicals scavengers, EGB 761 confirms its protective action on cells membranes and its anti-edema effect.

  7. The permeability of the posterior blood ocular barrier after xenon photocoagulation: a study using fluorescein labelled dextrans.

    OpenAIRE

    McNaught, E I; Foulds, W S; Johnson, N. F.

    1981-01-01

    Xenon photocoagulation burns in the rabbit fundus were studied angiographically with fluorescein labelled dextrans of molecular weights in the range 3000 to 150 000. Recent photocoagulation burns showed dye leakage to all molecular weights used. Angiograms 2 days after burns had been produced showed leakage of dextrans of molecular weights up to and including 70 000 but no leakage of dextran of 150 000 molecular weight. At 7 days after photocoagulation healed burns remained permeable to dextr...

  8. Real-time multimodal retinal image registration for a computer-assisted laser photocoagulation system.

    Science.gov (United States)

    Broehan, A Martina; Rudolph, Tobias; Amstutz, Christoph A; Kowal, Jens H

    2011-10-01

    An algorithm for the real-time registration of a retinal video sequence captured with a scanning digital ophthalmoscope (SDO) to a retinal composite image is presented. This method is designed for a computer-assisted retinal laser photocoagulation system to compensate for retinal motion and hence enhance the accuracy, speed, and patient safety of retinal laser treatments. The procedure combines intensity and feature-based registration techniques. For the registration of an individual frame, the translational frame-to-frame motion between preceding and current frame is detected by normalized cross correlation. Next, vessel points on the current video frame are identified and an initial transformation estimate is constructed from the calculated translation vector and the quadratic registration matrix of the previous frame. The vessel points are then iteratively matched to the segmented vessel centerline of the composite image to refine the initial transformation and register the video frame to the composite image. Criteria for image quality and algorithm convergence are introduced, which assess the exclusion of single frames from the registration process and enable a loss of tracking signal if necessary. The algorithm was successfully applied to ten different video sequences recorded from patients. It revealed an average accuracy of 2.47 ± 2.0 pixels (∼23.2 ± 18.8 μm) for 2764 evaluated video frames and demonstrated that it meets the clinical requirements.

  9. Acid Treatment of Titania Pastes to Create Scattering Layers in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Trystan Watson

    2012-01-01

    Full Text Available In dye-sensitized solar cells (DSC scattering layers are used to increase the path length of light incident on the TiO2 film. This is typically achieved by the deposition of an additional TiO2 layer on top of an existing transparent film and designed to trap light. In this work we show that a simple acid pretreatment can lead to the formation of a scattering “skin” on the surface of a single TiO2 film performing a similar function to a scattering layer without any additional depositions. This is important in increasing manufacturing throughput for DSCs as further TiO2 depositions require additional materials and heat treatment. The pretreatment leads to self-assembly of a scattering layer of TiO2 which covers the surface on short-term immersion (<30 min and penetrates the bulk layer upon longer immersion. The method has been shown to increase the efficiency of the device by 20%.

  10. Anaesthesia modalities during laser photocoagulation for retinopathy of prematurity: a retrospective, longitudinal study.

    Science.gov (United States)

    Jiang, Jing-Bo; Strauss, Randy; Luo, Xian-Qiong; Nie, Chuan; Wang, Yan-Li; Zhang, Jia-Wen; Zhang, Zhi-Wei

    2017-01-24

    Laser photocoagulation surgery is a routine treatment for threshold retinopathy of prematurity (ROP). However, little is known about which anaesthesia protocols provide efficient pain control while minimising exposure risk to vulnerable infants. In this study, therefore, we assessed the efficacy and tolerability of multiple anaesthesia techniques used on premature infants during laser therapy. Anaesthesia modalities consisted of topical eye drops anaesthesia, general anaesthesia and intravenous fentanyl sedation with mechanical ventilation. Laser treatment efficacy and detailed operative information were retrospectively and consecutively analysed. Cardiorespiratory stability was assessed and compared. The Neonatal Pain Agitation and Sedation Scale (N-PASS) was used to evaluate tolerability in infants that underwent intravenous fentanyl sedation. 97 cases of prematurity were included in this study. In 94/97 (96.9%) cases, vascular proliferation regressed. In the topical anaesthesia groups, the ophthalmologist needed 12-16 min more to complete the treatment. During the 3 postoperative days, topical anaesthesia demonstrated the greatest instability; 4/31 (12.90%) infants in this group suffered from life threatening events requiring resuscitation. The only instability observed in general anaesthesia and fentanyl sedation was attributed to difficulty in extubating within 24 hours after surgery. During laser therapy, the N-PASS score increased to 1.8 in the fentanyl sedation group. Topical anaesthesia was associated with more cardiorespiratory instability during ROP laser treatment. While general anaesthesia and fentanyl sedation had similar postoperative cardiorespiratory results, the latter demonstrated acceptable pain stress control. However, the difficulty of weaning off mechanical ventilation in some cases after surgery needs to be addressed in future studies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a

  11. In-vivo wound healing modulation after irradiation with a blue LED photocoagulator

    Science.gov (United States)

    Rossi, Francesca; Cicchi, Riccardo; Magni, Giada; Tatini, Francesca; Bacci, Stefano; Paroli, Gaia; Alfieri, Domenico; Tripodi, Cristina; De Siena, Gaetano; Pavone, Francesco S.; Pini, Roberto

    2017-07-01

    A faster healing process was observed in superficial skin wounds after irradiation with a blue LED (EmoLED) photocoagulator. EmoLED is a compact handheld device, used to induce a thermal effect and thus coagulation in superficial abrasions. We present the results of an in vivo study, conducted in different mouse model, to analyze the induced wound healing. Two superficial abrasions were produced on the back of the mice: one area was treated with EmoLED (1.4 W/cm2, 30 s treatment time), while the other one was left naturally recovering. During the treatment, a temperature around 40-45°C was induced on the abrasion surface. Mice back healthy skin was used as a control. We compared the treatment in black mice, healthy albino mice, diabetic albino mice and albino mice with coagulation problem. The animals underwent a follow up study and were sacrificed at 0, 3, 6, 9, 18, 24 hours p.o.. Samples from the two abraded areas were harvested and examined by histopathological and immunofluorescence analysis, SHG imaging and confocal microscopy. The aim of the study was to compare the effects in the different target groups and to investigate the early phase of the wound healing process. Our results show that the effects are comparable in all the treated groups and that the healing process appears to be faster in respect to the naturally recovered wounds. This study confirms the previous results obtained in a study on a rat model an in a study on healthy albino mice: the selective photothermal effect we used for inducing immediate coagulation in superficial wounds seems to be associated to a faster and improved healing process.

  12. The rationale of argon green laser photocoagulation for diabetic maculopathy.

    Directory of Open Access Journals (Sweden)

    Dastur Y

    1994-01-01

    Full Text Available Eighty-four patients of bilateral diabetic retinopathy were divided into 2 groups: Group I comprised of 60 patients (mean age 46 yrs having non-proliferative diabetic retinopathy with maculopathy (total no. of eyes = 120. Group II consisted of 24 patients (mean age 49.1 yrs with proliferative diabetic retinopathy with maculopathy (total no. of eyes under study = 48. One eye of each patient in group I was treated as a control and the other was subjected to focal laser therapy. While 48/60 control Group I eyes (80% had 6/24 vision at the outset, at one year follow-up only 39/60 cases (65% had 6/24 vision. Diabetic maculopathy persisted in all the 60 control eyes at one year. In contrast, 44/60 eyes (73% subjected to focal laser therapy in Group I, had 6/24 vision at outset but one year later, 49/60 eyes (81% had 6/24 vision. Maculopathy completely regressed in 48/60 eyes (80%. The 48 eyes of Group II patients were subjected to focal and scatter laser therapy. 20/48 eyes (41.6% had 6/24 vision prior to treatment but one year after treatment, 25/48 eyes (52% had 6/24 vision. Neovascularization and macular edema regressed after one year in 42/48 eyes (87.1% and only 4/48 eyes (8.3% developed localized vitreous hemorrhage. Laser therapy in Group I improved visual acuity by reducing macular edema. In Group II, it improved the vision and reduced the risk of vitreous hemorrhage, detachment and glaucoma.

  13. Macular laser photocoagulation guided by spectral-domain optical coherence tomography versus fluorescein angiography for diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Gallego-Pinazo R

    2011-05-01

    Full Text Available Roberto Gallego-Pinazo1,2, Ana Marina Suelves-Cogollos1, Rosa Dolz-Marco1, J Fernando Arevalo3, Salvador García-Delpech1, J Luis Mullor4, Manuel Díaz-Llopis1,2,51Department of Ophthalmology, Hospital Universitario La Fe, Valencia, Spain; 2Centro de Investigación Biomédica en Red de Enfermedades Raras, Valencia, Spain; 3Retina and Vitreous Service, Clinical Ophthalmology Center, Caracas, Venezuela; 4Unit of Experimental Ophthalmology, Hospital Universitario La Fe, Valencia, Spain; 5University of Valencia, Faculty of Medicine, Valencia, SpainBackground: The aim of this study was to compare the efficacy of spectral-domain optical coherence tomography (SD-OCT and fluorescein angiography (FA in the guidance of macular laser photocoagulation for diabetic macular edema.Methods: This was a prospective interventional clinical comparative pilot study. Forty eyes from 24 consecutive patients with diabetic macular edema were allocated to receive laser photocoagulation guided by SD-OCT or FA. Best-corrected visual acuity (BCVA, central macular thickness, and retinal volume were assessed at baseline and two months after treatment.Results: Subjects treated using FA-guided laser improved BCVA from the logarithm of the minimum angle of resolution (logMAR 0.52 ± 0.2 to 0.37 ± 0.2 (P < 0.001, and decreased mean central macular thickness from 397.25 ± 139.1 to 333.50 ± 105.7 µm (P < 0.001 and retinal volume from 12.61 ± 1.6 to 10.94 ± 1.4 mm3 (P < 0.001. Subjects treated using SD-OCT guided laser had improved BCVA from 0.48 ± 0.2 to 0.33 ± 0.2 logMAR (P < 0.001, and decreased mean central macular thickness from 425.90 ± 149.6 to 353.4 ± 140 µm (P < 0.001 and retinal volume from 12.38 ± 2.1 to 11.53 ± 1.1 mm3 (P < 0.001. No significant differences between the groups were found in two-month BCVA (P = 0.505, two-month central macular thickness (P = 0.660, or two-month retinal volume (P = 0.582.Conclusion: The short-term results of this pilot study

  14. Temporal changes in retinal vascular parameters associated with successful panretinal photocoagulation in proliferative diabetic retinopathy

    DEFF Research Database (Denmark)

    Torp, Thomas Lee; Kawasaki, Ryo; Wong, Tien Yin

    2018-01-01

    PURPOSE: We aimed to investigate changes in retinal vascular geometry over time after panretinal photocoagulation (PRP) in patients with proliferative diabetic retinopathy (PDR). METHODS: Thirty-seven eyes with PDR were included. Wide-field fluorescein angiography (Optomap, Optos PLC., Dunfermlin...

  15. Noninvasive monitoring of the thermal stress in RPE using light scattering spectroscopy

    Science.gov (United States)

    Schule, Georg; Huie, Philip; Vankov, Alexander B.; Vitkin, Edward; Fang, Hui; Hanlon, Eugene B.; Perelman, Lev T.; Palanker, Daniel V.

    2004-07-01

    Introduction: Light Scattering Spectroscopy has been a recently developed as a non-invasive technique capable of sizing the cellular organelles. With this technique, we monitor the heat-induced sub-cellular structural transformations in a human RPE cell culture. Material and Methods: A single layer of human RPE cells (ATCC) was grown on a glass slide. Cells are illuminated with light from a fiber-coupled broadband tungsten lamp. The backscattered (180 degree) light spectra are measured with an optical multichannel analyzer (OMA). Spectra are measured during heating of the sample. Results: We reconstructed the size distribution of sub-micron organelles in the RPE cells and observed temperature-related changes in the scattering density of the organelles in the 200-300nm range (which might be peroxisomes, microsomes or lysosomes). The sizes of the organelles did not vary with temperature, so the change in scattering is most probably due to the change in the refractive indexes. As opposed to strong spectral variation with temperature, the total intensity of the backscattered light did not significantly change in the temperature range of 32-49 °C. Conclusion: We demonstrate that Light Scattering Spectroscopy is a powerful tool for monitoring the temperature-induced sub-cellular transformations. This technique providing an insight into the temperature-induced cellular processes and can play an important role in quantitative assessment of the laser-induced thermal effects during retinal laser treatments, such as Transpupillary Thermal Therapy (TTT), photocoagulation, and Photodynamic Therapy (PDT).

  16. Evaluation of the Treatment of Diabetic Retinopathy A Research Project

    Science.gov (United States)

    Kupfer, Carl

    1973-01-01

    Evaluated is the treatment of diabetic retinopathy (blindness due to ruptured vessels of the retina as a side effect of diabetes), and described is a research project comparing two types of photocoagulation treatment. (DB)

  17. Changes in retinal venular oxygen saturation predict activity of proliferative diabetic retinopathy 3 months after panretinal photocoagulation

    DEFF Research Database (Denmark)

    Torp, Thomas Lee; Kawasaki, Ryo; Wong, Tien Yin

    2018-01-01

    BACKGROUND/AIMS: Proliferative diabetic retinopathy (PDR) is a severe blinding condition. We investigated whether retinal metabolism, measured by retinal oximetry, may predict PDR activity after panretinal laser photocoagulation (PRP). METHODS: We performed a prospective, interventional, clinical...

  18. Corneal perforation associated with argon laser photocoagulation for a retinal tear.

    Science.gov (United States)

    Keithahn, M A; Gross, R H; Mannis, M J; Morales, R B; Morse, L S

    1997-01-01

    To report a corneal perforation during argon laser photocoagulation around a retinal tear following pneumatic retinopexy. The patient was examined and found to have a corneal perforation with pigment in the base of the wound. To help explain this phenomenon, we evaluated the ability of argon blue-green laser to create a corneal perforation in a cadaver eye. In a cadaver eye, we induced a corneal perforation with argon laser only when a pigmented substance was present on the corneal surface. We hypothesize that pigmented material such as an eyelash or mascara caught between the cornea and contact lens interface may have facilitated this rare complication. Clinicians should be wary of any pigmented substance on the surface of the cornea or ophthalmoscopic lens when performing argon laser photocoagulation.

  19. Photocoagulation of dermal blood vessels with multiple laser pulses in an in vivo microvascular model.

    Science.gov (United States)

    Jia, Wangcun; Tran, Nadia; Sun, Victor; Marinček, Marko; Majaron, Boris; Choi, Bernard; Nelson, J Stuart

    2012-02-01

    Current laser therapy of port wine stain (PWS) birthmarks with a single laser pulse (SLP) does not produce complete lesion removal in the majority of patients. To improve PWS therapeutic efficacy, we evaluated the performance of an approach based on multiple laser pulses (MLP) to enhance blood vessel photocoagulation. The hamster dorsal window chamber model was used. Radiant exposure (RE), pulse repetition rate (f(r)), total number of pulses (n(p)), and length of vessel irradiated were varied. Blood vessels in the window were irradiated with either SLP with RE of 4-7 J/cm(2) or MLP with RE per pulse of 1.4-5.0 J/cm(2), f(r) of 0.5-26.0 Hz, and n(p) of 2-5. The laser wavelength was 532 nm and pulse duration was 1 ms. Either a 2 mm vessel segment or entire vessel branch was irradiated. Digital photographs and laser speckle images of the window were recorded before and at specific time points after laser irradiation to monitor laser-induced blood vessel structural and functional changes, respectively. We found that: (1) for a SLP approach, the RE required to induce blood vessel photocoagulation was 7 J/cm(2) as compared to only 2 J/cm(2) per pulse for the MLP approach; (2) for MLP, two pulses at a repetition rate of 5 Hz and a RE of 3 J/cm(2) can induce photocoagulation of more than 80% of irradiated blood vessel; and (3) irradiation of a longer segment of blood vessel resulted in lower reperfusion rate. The MLP approach can induce blood vessel photocoagulation at much lower RE per pulse as compared to SLP. The 5 Hz f(r) and the need for two pulses are achievable with modern laser technology, which makes the MLP approach practical in the clinical management of PWS birthmarks. Copyright © 2012 Wiley Periodicals, Inc.

  20. A Comparative Study of Retinal Function in Rabbits after Panretinal Selective Retina Therapy versus Conventional Panretinal Photocoagulation

    Directory of Open Access Journals (Sweden)

    Young Gun Park

    2015-01-01

    Full Text Available Purpose. This study evaluates functional changes in electroretinographic findings after selective retina therapy (SRT compared to panretinal photocoagulation (PRP in rabbits. Methods. The right eyes of 12 Chinchilla rabbits received 200 laser treatment spots. The right eyes of six rabbits received SRT (SRT group, whereas the other six animals were treated using PRP on the right eye (PRP group. The eyes were investigated using full-field ERG 1 hour and 3 weeks after treatment. Histologic exam to assess the tissue response of lasers was performed on 3 weeks. Results. No significant changes in the mean ROD or CR b-wave amplitudes of the SRT lesions were evident, compared to baseline, 1 h after laser treatment (p=0.372 and 0.278, resp.. In addition, the OPs and 30 Hz flickers of the SRT lesions were not significantly altered (p=0.17 and 0.243, resp.. At 3 weeks, similar results were found. Comparing the two groups, the ROD b-wave amplitude was reduced in the PRP and SRT groups to 60.04±4.2% and 92.32±6.43% of baseline (p<0.001. Histologically, there was no visible photoreceptor alterations on week 3. Conclusions. SRT in rabbit eyes induced less functional loss than PRP in both rod-mediated retinal function and cone-mediated retinal function. In addition, SRT irradiated eyes had no functional loss compared to its control.

  1. Correlation with OCT and histology of photocoagulation lesions in patients and rabbits.

    Science.gov (United States)

    Koinzer, Stefan; Saeger, Mark; Hesse, Carola; Portz, Lea; Kleemann, Susanne; Schlott, Kerstin; Brinkmann, Ralf; Roider, Johann

    2013-12-01

    To examine spectral domain optical coherence tomographic (OCT) and histological images from comparable retinal photocoagulation lesions in rabbits, and to correlate these images with comparable OCT images from patients. 508 rabbit lesions were examined by HE-stained paraffin histology. 1019 rabbit lesions versus 236 patient lesions were examined by OCT, all at the time-points 1 hr, 1 week and 4 weeks after photocoagulation. We analysed 100 μm lesions (in humans) and 133 μm lesions (in rabbits) of 200 ms exposures at powers titrated from the histological threshold up to intense damage. Lesions were matched according to morphological criteria. Dome-shaped layer alterations, retinal infiltration by round, pigmented cells, outer nuclear layer interruption, and eventually full thickness retinal coagulation are detectable in histology and OCT. Horizontal damage extensions are found 1½ times larger in OCT. More intense irradiation was necessary to induce comparable layer affection in rabbit OCT as in histology. Restoration of the inner retinal layers is only shown in the OCT images. Comparable primary lesions caused more pronounced OCT changes in patients than in rabbits during healing. Optical coherence tomographic images indicate different tissue changes than histologic images. After photocoagulation, they show wider horizontal damage diameters, but underestimate axial damage particularly during healing. Conclusions on retinal restoration should not be drawn from OCT findings alone. Retinal recovery after comparable initial lesions appears to be more complete in rabbit than in patient OCTs. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  2. Evaluation of ocular and periocular elasticity after panretinal photocoagulation: an ultrasonic elastography study.

    Science.gov (United States)

    Pekel, Gökhan; Ağladıoğlu, Kadir; Acer, Semra; Yağcı, Ramazan; Kaşıkçı, Alper

    2015-03-01

    Our aim was to evaluate the effects of argon laser panretinal photocoagulation on ocular and periocular ultrasound elastography values in diabetic retinopathy. Also, we wanted to test the applicability of ultrasound elastography in ophthalmological practice. This is a prospective cross-sectional study comparing proliferative diabetic retinopathy patients (study group) who had undergone panretinal photocoagulation and non-proliferative diabetic retinopathy patients (control group). There were 15 participants (11 males and 4 females) in the study group and 16 participants (10 males and 6 females) in the control group. The ultrasound elastography measurements were done with the LOGİQ E9 Ultrasound Elastography. The elastography values of vitreous, retrobulbar fat, and optic nerve were similar in both groups (p > 0.05). But, the mean retina-choroid-scleral elastography value of the study group was higher than that of the control group, which indicates increased hardness (p = 0.002). The argon laser panretinal photocoagulation decreases elasticity of the retina-choroid-sclera complex. The ultrasound elastography technique, that gives reproducible and consistent values, could be used effectively in ophthalmological practice.

  3. The effect of laser pan-retinal photocoagulation with or without intravitreal bevacizumab injections on the OCT-measured macular choroidal thickness of eyes with proliferative diabetic retinopathy.

    Science.gov (United States)

    Preti, Rony C; Mutti, Anibal; Ferraz, Daniel A; Zacharias, Leandro C; Nakashima, Yoshitaka; Takahashi, Walter Y; Monteiro, Mario L R

    2017-02-01

    To investigate the effect of laser pan-retinal photocoagulation with or without intravitreal bevacizumab injections on macular choroidal thickness parameters in eyes with high-risk proliferative diabetic retinopathy. High-risk proliferative diabetic retinopathy patients undergoing laser treatment were prospectively enrolled in this study. One eye was randomly selected for laser treatment combined with bevacizumab injections, study group, whereas the corresponding eye was subjected to laser treatment alone, control group. Spectral-domain optical coherence tomography with enhanced depth imaging was used to measure the macular choroidal thickness prior to and 1 month after treatment. Measurements in both groups were compared. Clinicaltrials.gov: NCT01389505. Nineteen patients (38 eyes) with a mean±standard deviation age of 53.4±9.3 years were evaluated, and choroidal thickness measurements for 15 patients were used for comparison. The greatest measurement before treatment was the subfoveal choroidal thickness (341.68±67.66 μm and 345.79±83.66 μm for the study and control groups, respectively). No significant difference between groups was found in terms of macular choroidal thickness measurements at baseline or after treatment. However, within-group comparisons revealed a significant increase in choroidal thickness parameters in 10 measurements in the study group and in only 5 temporal measurements in the control group when 1-month follow-up measurements were compared to baseline values. The macular choroidal thickness does not appear to be significantly influenced by laser treatment alone but increases significantly when associated with bevacizumab injections in patients with proliferative diabetic retinopathy and macular edema. Because bevacizumab injections reduce short-term laser pan-retinal photocoagulation-induced macular edema, our findings suggest that the choroid participates in its pathogenesis.

  4. Intravitreal Bevacizumab Alone or Combined with Macular Laser Photocoagulation for Recurrent or Persistent Macular Edema Secondary to Branch Retinal Vein Occlusion

    Directory of Open Access Journals (Sweden)

    Takafumi Hirashima

    2014-01-01

    Full Text Available Background. To evaluate the efficacy of intravitreal bevacizumab (IVB injection with or without macular laser photocoagulation (MLP for recurrent or persistent macular edema (ME secondary to branch retinal vein occlusion (BRVO. Methods. Thirty-four eyes underwent IVB injection for ME secondary to BRVO as a primary treatment. Twenty of the 34 eyes experienced recurrent or persistent ME after the first IVB. Nine of the 20 eyes (Group 1 were retreated with IVB combined with MLP. The remaining 11 eyes (Group 2 were retreated with IVB alone. Results. In Group 1, the postoperative best corrected visual acuity (BCVA improved compared with the preoperative value at all follow-up visits, although no statistically significant improvement was observed at 6 months. In contrast, BCVA significantly improved from 0.53 to 0.40 at 6 months (P<0.05 in Group 2. Conclusion. Combined therapy tended to have a smaller effect on visual acuity compared with IVB monotherapy.

  5. Imaging microscopic distribution of antifungal agents in dandruff treatments with stimulated Raman scattering microscopy

    Science.gov (United States)

    Garrett, Natalie L.; Singh, Bhumika; Jones, Andrew; Moger, Julian

    2017-06-01

    Treatment of dandruff condition usually involves use of antidandruff shampoos containing antifungal agents. Different antifungal agents show variable clinical efficacy based on their cutaneous distribution and bioavailability. Using stimulated Raman scattering (SRS), we mapped the distribution of unlabeled low-molecular weight antifungal compounds zinc pyrithione (ZnPT) and climbazole (CBZ) on the surface of intact porcine skin with cellular precision. SRS has sufficient chemical selectivity and sensitivity to detect the agents on the skin surface based on their unique chemical motifs that do not occur naturally in biological tissues. Moreover, SRS is able to correlate the distribution of the agents with the morphological features of the skin using the CH2 stretch mode, which is abundant in skin lipids. This is a significant strength of the technique since it allows the microscopic accumulation of the agents to be correlated with physiological features and their chemical environment without the use of counter stains. Our findings show that due to its lower solubility, ZnPT coats the surface of the skin with a sparse layer of crystals in the size range of 1 to 4 μm. This is consistent with the current understanding of the mode of action of ZnPT. In contrast, CBZ being more soluble and hydrophobic resulted in diffuse homogeneous distribution. It predominantly resided in microscopic lipid-rich crevasses and penetrated up to 60 μm into the infundibular spaces surrounding the hair shaft. The ability of the SRS to selectively map the distribution of agents on the skin's surface has the potential to provide insight into the mechanisms underpinning the topical application of antifungal or skin-active agents that could lead to the rational engineering of enhanced formulations.

  6. Risk of a second cancer from scattered radiation in acoustic neuroma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Myonggeun; Lee, Hyunho; Sung, Jiwon [Korea University, Seoul (Korea, Republic of); Shin, Dongoh [Kyung Hee University Medical Center, Seoul (Korea, Republic of); Park, Sungho [Ulsan University Hospital, Ulsan (Korea, Republic of); Chung, Weonkuu; Jahng, Geonho; Kim, Dongwook [Kyung Hee University Hospital at Gangdong, Seoul (Korea, Republic of)

    2014-06-15

    The present study aimed to compare the risk of a secondary cancer from scattered and leakage doses in patients receiving intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic radiosurgery (SRS). Four acoustic neuroma patients were treated with IMRT, VMAT, or SRS. Their excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) of a secondary cancer were estimated using the corresponding secondary doses measured at various organs by using radio-photoluminescence glass dosimeters (RPLGD) placed inside a humanoid phantom. When a prescription dose was delivered in the planning target volume of the 4 patients, the average organ equivalent doses (OED) at the thyroid, lung, liver, bowel, bladder, prostate (or ovary), and rectum were 14.6, 1.7, 0.9, 0.8, 0.6, 0.6, and 0.6 cGy, respectively, for IMRT whereas they were 19.1, 1.8, 2.0, 0.6, 0.4, 0.4, and 0.4 cGy, respectively, for VMAT, and 22.8, 4.6, 1.4, 0.7, 0.5, 0.5, and 0.5 cGy, respectively, for SRS. The OED decreased as the distance from the primary beam increased. The thyroid received the highest OED compared to other organs. A lifetime attributable risk evaluation estimated that more than 0.03% of acoustic neuroma (AN) patients would get radiation-induced cancer within 20 years of receiving radiation therapy. The organ with the highest radiation-induced cancer risk after radiation treatment for AN was the thyroid. We found that the LAR could be increased by the transmitted dose from the primary beam. No modality-specific difference in radiation-induced cancer risk was observed in our study.

  7. Risk of a second cancer from scattered radiation in acoustic neuroma treatment

    Science.gov (United States)

    Yoon, Myonggeun; Lee, Hyunho; Sung, Jiwon; Shin, Dongoh; Park, Sungho; Chung, Weon Kuu; Jahng, Geon-Ho; Kim, Dong Wook

    2014-06-01

    The present study aimed to compare the risk of a secondary cancer from scattered and leakage doses in patients receiving intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic radiosurgery (SRS). Four acoustic neuroma patients were treated with IMRT, VMAT, or SRS. Their excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) of a secondary cancer were estimated using the corresponding secondary doses measured at various organs by using radio-photoluminescence glass dosimeters (RPLGD) placed inside a humanoid phantom. When a prescription dose was delivered in the planning target volume of the 4 patients, the average organ equivalent doses (OED) at the thyroid, lung, liver, bowel, bladder, prostate (or ovary), and rectum were 14.6, 1.7, 0.9, 0.8, 0.6, 0.6, and 0.6 cGy, respectively, for IMRT whereas they were 19.1, 1.8, 2.0, 0.6, 0.4, 0.4, and 0.4 cGy, respectively, for VMAT, and 22.8, 4.6, 1.4, 0.7, 0.5, 0.5, and 0.5 cGy, respectively, for SRS. The OED decreased as the distance from the primary beam increased. The thyroid received the highest OED compared to other organs. A lifetime attributable risk evaluation estimated that more than 0.03% of acoustic neuroma (AN) patients would get radiation-induced cancer within 20 years of receiving radiation therapy. The organ with the highest radiation-induced cancer risk after radiation treatment for AN was the thyroid. We found that the LAR could be increased by the transmitted dose from the primary beam. No modality-specific difference in radiation-induced cancer risk was observed in our study.

  8. Determination of pulse profile characteristics of multi spot retinal photocoagulation lasers.

    Science.gov (United States)

    Clarkson, Douglas McG; Makhzoum, Osama; Blackburn, John

    2015-10-01

    A system is described for determination of discrete pulse train characteristics of multi spot laser delivery systems for retinal photocoagulation. While photodiodes provide an ideal detection mechanism, measurement artifacts can potentially be introduced by the spatial pattern of the delivered beam relative to a discrete photodiode element. This problem was overcome by use of an integrating sphere to produce a uniform light field at the site of the photodiode detector. A basic current driven photodiode detection circuit incorporating an operational amplifier was used to generate a signal captured by a commercially available USB interface device at a rate of 10 kHz. Studies were undertaken of a Topcon Pascal Streamline laser system with output at a wavelength of 577 nm (yellow). This laser features the proprietary feature of 'Endpoint Management' ™ where pulses can be delivered as 100% of set energy levels with visible reaction on the retina and also at a reduced energy level to create potentially non visible but clinically effective lesions. Using the pulse train measurement device it was identified that the 'Endpoint Management' ™ delivery mode of pulses of lower energy was achieved by reducing the pulse duration of pulses for non-visible effect pulses while maintaining consistent beam power levels within the delivered pulse profile. The effect of eye geometry in determining safety and effectiveness of multi spot laser delivery for retinal photocoagulation is discussed. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  9. Fetoscopic laser photocoagulation for amniotic fluid discordance bordering on twin-twin transfusion syndrome: Feasibility, perinatal and long-term outcomes.

    Science.gov (United States)

    Ozawa, Katsusuke; Sugibayashi, Rika; Wada, Seiji; Sumie, Masahiro; Ishii, Keisuke; Nakata, Masahiko; Murakoshi, Takeshi; Ito, Yushi; Sago, Haruhiko

    2017-08-01

    This study investigated the feasibility and safety of fetoscopic laser photocoagulation (FLP) for amniotic fluid discordance (AFD) bordering on twin-twin transfusion syndrome (TTTS) with an absent or reverse end-diastolic velocity (AREDV) in the umbilical artery (UA), and evaluated the perinatal and long-term outcomes. A prospective intervention study was performed between 20 + 0 and 25 + 6 weeks of gestation (UMIN000004165). AFD bordering on TTTS was defined as maximum vertical pocket (MVP) of amniotic fluid in one twin's sac ≤3 cm and amniotic fluid MVP in the other twin's sac ≥7 cm excluding TTTS. Neurodevelopmental outcome was evaluated at 6 months and at 3 years of age. Eleven women were treated without complications between September 2010 and July 2011. In all cases amnioinfusion was required, with a median surgical time of 70 min. There were nine cases of selective intrauterine growth restriction in which the growth discordant rate was >25%. The survival rates of the donor and recipient twins were 27.3% (3/11) and 100% (11/11), respectively. None of the surviving donor twins and two of the 11 recipient twins had hemiplegia at 6 months of age. One additional recipient twin had developmental delay at 3 years of age. Fetoscopic laser photocoagulation for AFD bordering on TTTS with AREDV in the UA was feasible without complications but frequently resulted in donor twin death and a high survival rate of the recipient twin, albeit with neurodevelopmental abnormalities in some cases. FLP does not seem to be a promising treatment option for AFD bordering on TTTS. © 2017 Japan Society of Obstetrics and Gynecology.

  10. Creation, destruction, and transfer of atomic multipole moments by electron scattering: Quantum-mechanical treatment

    Science.gov (United States)

    Csanak, G.; Kilcrease, D. P.; Fursa, D. V.; Bray, I.

    2008-12-01

    Using the wave-packet propagation method of Rodberg and Thaler and the density matrix method of Fano and Blum, we have defined by completely quantum-mechanical methods the cross sections for the creation, destruction, and transfer of atomic multipole moments by both elastic and inelastic scattering of electrons by atomic targets. All cross sections obtained quantum mechanically, except for the coherence transfer cross sections, agree in form with those obtained semiclassically by Fujimoto and co-workers. We also used the converged close-coupling (CCC) method to calculate numerically some of the above cross sections for selected transitions in electron scattering from hydrogen and barium atoms.

  11. Improvement in retinal venous oxygen saturation after panretinal photocoagulation is predictive of progression of proliferative diabetic retinopathy

    DEFF Research Database (Denmark)

    Torp, Thomas Lee; Kawasaki, Ryo; Wong, Tien Yin

    We performed a prospective, interventional clinical study on patients with proliferative diabetic retinopathy (PDR) in order to investigate changes in retinal oximetry before and three months after panretinal photocoagulation (PRP) and to correlate this to PDR-activity. Thirty-nine eyes from 34 p...

  12. Finite volume treatment of $\\pi\\pi$ scattering in the $\\rho$ channel

    CERN Document Server

    Albaladejo, M; Oller, J A; Roca, L

    2013-01-01

    We make a theoretical study of $\\pi\\pi$ scattering with quantum numbers $J^{PC}=1^{--}$ in a finite box. To calculate physical observables for infinite volume from lattice QCD, the finite box dependence of the potentials is not usually considered. We quantify such effects by means of two different approaches for vector-isovector $\\pi\\pi$ scattering based on Unitarized Chiral Perturbation Theory results: the Inverse Amplitude Method and another one based on the $N/D$ method. We take into account finite box effects stemming from higher orders through loops in the crossed $t,u-$channels as well as from the renormalization of the coupling constants. The main conclusion is that for $\\pi\\pi$ phase shifts in the isovector channel one can safely apply L\\"uscher based methods for finite box sizes of $L$ greater than $2 m_\\pi^{-1}$.

  13. Variational treatment of electron-polyatomic-molecule scattering calculations using adaptive overset grids

    Science.gov (United States)

    Greenman, Loren; Lucchese, Robert R.; McCurdy, C. William

    2017-11-01

    The complex Kohn variational method for electron-polyatomic-molecule scattering is formulated using an overset-grid representation of the scattering wave function. The overset grid consists of a central grid and multiple dense atom-centered subgrids that allow the simultaneous spherical expansions of the wave function about multiple centers. Scattering boundary conditions are enforced by using a basis formed by the repeated application of the free-particle Green's function and potential Ĝ0+V ̂ on the overset grid in a Born-Arnoldi solution of the working equations. The theory is shown to be equivalent to a specific Padé approximant to the T matrix and has rapid convergence properties, in both the number of numerical basis functions employed and the number of partial waves employed in the spherical expansions. The method is demonstrated in calculations on methane and CF4 in the static-exchange approximation and compared in detail with calculations performed with the numerical Schwinger variational approach based on single-center expansions. An efficient procedure for operating with the free-particle Green's function and exchange operators (to which no approximation is made) is also described.

  14. X-ray scattering evaluation of ultrastructural changes in human dental tissues with thermal treatment.

    Science.gov (United States)

    Sandholzer, Michael A; Sui, Tan; Korsunsky, Alexander M; Walmsley, Anthony Damien; Lumley, Philip J; Landini, Gabriel

    2014-05-01

    Micro- and ultrastructural analysis of burned skeletal remains is crucial for obtaining a reliable estimation of cremation temperature. Earlier studies mainly focused on heat-induced changes in bone tissue, while this study extends this research to human dental tissues using a novel quantitative analytical approach. Twelve tooth sections were burned at 400-900°C (30-min exposure, increments of 100°C). Subsequent combined small- and wide-angle X-ray scattering (SAXS/WAXS) experiments were performed at the Diamond Light Source synchrotron facility, where 28 scattering patterns were collected within each tooth section. In comparison with the control sample, an increase in mean crystal thickness was found in burned dentine (2.8-fold) and enamel (1.4-fold), however at a smaller rate than reported earlier for bone tissue (5-10.7-fold). The results provide a structural reference for traditional X-ray scattering methods and emphasize the need to investigate bone and dental tissues separately to obtain a reliable estimation of cremation temperature. © 2014 American Academy of Forensic Sciences.

  15. Miniaturized high-resolution wide-field contact lens for panretinal photocoagulation

    Directory of Open Access Journals (Sweden)

    Koushan K

    2014-04-01

    Full Text Available Keyvan Koushan, KV Chalam Department of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL, USA Background and objective: We describe a miniaturized lightweight high-refractive-index panretinal contact lens for diagnostic and therapeutic visualization of the peripheral retina. Instrument design: The miniaturized high-resolution wide-field contact lens includes three optical elements in a light (15 g and miniaturized (16 mm footplate, 24 mm external aperture, and 21 mm vertical height casing contributing to a total dioptric power of +171 diopters. This lens provides up to 165° visualization of the retina for diagnostic and therapeutic applications while allowing easier placement due to its miniaturization. Conclusion: This new lens (50% lighter and 89% smaller improves upon earlier contact lenses for visualization of the peripheral retina. Keywords: contact lens, panretinal photocoagulation, retinal examination, peripheral retina, high resolution view, wide-angle lens, lens

  16. Fulminant proliferative diabetic retinopathy in the non-photocoagulated eye following acute renal failure.

    Science.gov (United States)

    Jang, Liuna; Herbort, Carl P

    2016-12-01

    Management of diabetic retinopathy should follow more strict and aggressive rules in patients at risk for severe acute renal impairment. Such patients should be identified and possibly prophylactically laser treated to avoid the severe consequences demonstrated in this case report. A 34-year-old type 2 diabetes patient with a stabilized diabetic retinopathy developed acute and severe retinal decompensation within weeks after acute renal failure complicated his chronic stable renal impairment. Fluorescein angiographic and optical coherence tomographic illustrations of the rapid evolution of the retinal condition are presented. The patient had previously been treated with panretinal photocoagulation in his left eye. After 8 years of regular 6-monthly checked stability, he developed rapid-onset proliferative diabetic retinopathy and macular edema in his right eye within 3 months of his last ocular check-up. Fluorescein angiography showed neovessels and major ischemic areas. Emergency panretinal photocoagulation and a sub-Tenon's injection were necessary to achieve control of the situation with regression of neovessels and complete regression of macular edema. This case shows that it is imperative for nephrologists to be well informed about a patient's ocular situation in order to give timely information to the ophthalmologist who can intervene to protect the retina in case of renal failure. On the other hand, the ophthalmologist should be familiar with the renal function of his patient with renal impairment so that he can decide to perform prophylactic retinal panphotocoagulation that should be imperatively considered even without strict indications in patients with renal impairment at risk for further deterioration of renal function, in order to prevent such explosive ischemic and proliferative retinopathy putting vision at risk.

  17. Finite volume treatment of pi pi scattering and limits to phase shifts extraction from lattice QCD

    CERN Document Server

    Albaladejo, M; Oset, E; Rios, G; Roca, L

    2012-01-01

    We study theoretically the effects of finite volume for pipi scattering in order to extract physical observables for infinite volume from lattice QCD. We compare three different approaches for pipi scattering (lowest order Bethe-Salpeter approach, N/D and inverse amplitude methods) with the aim to study the effects of the finite size of the box in the potential of the different theories, specially the left-hand cut contribution through loops in the crossed t,u-channels. We quantify the error made by neglecting these effects in usual extractions of physical observables from lattice QCD spectra. We conclude that for pipi phase-shifts in the scalar-isoscalar channel up to 800 MeV this effect is negligible for box sizes bigger than 2.5m_pi^-1 and of the order of 5% at around 1.5-2m_pi^-1. For isospin 2 the finite size effects can reach up to 10% for that energy. We also quantify the error made when using the standard Luscher method to extract physical observables from lattice QCD, which is widely used in the lite...

  18. The effect of pattern scan laser photocoagulation on peripapillary retinal nerve fiber layer thickness and optic nerve morphology in diabetic retinopathy.

    Science.gov (United States)

    Lee, Dong Eik; Lee, Ju Hyang; Lim, Han Woong; Kang, Min Ho; Cho, Hee Yoon; Seong, Mincheol

    2014-10-01

    To evaluate the effect of pattern scan laser (PASCAL) photocoagulation on peripapillary retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), and optic nerve morphology in patients with diabetic retinopathy. Subjects included 35 eyes for the PASCAL group and 49 eyes for a control group. Peripapillary RNFL thickness, cup-disc area ratio and CMT were measured before PASCAL photocoagulation and at 2 and 6 months after PASCAL photocoagulation in the PASCAL or control groups. The average RNFL thickness had increased by 0.84 µm two months after and decreased by 0.4 µm six months after PASCAL photocoagulation compared to baseline, but these changes were not significant (p = 0.83, 0.39). The cup-disc area ratio was unchanged after PASCAL photocoagulation. CMT increased by 18.11 µm (p = 0.048) at two months compared to baseline thickness, and partially recovered to 11.82 µm (p = 0.11) at six months in the PASCAL group. PASCAL photocoagulation may not cause significant change in the peripapillary RNFL thickness, CMT, and optic nerve morphology in patients with diabetic retinopathy.

  19. Effect of laser photocoagulation and bevacizumab intravitreal in proliferative diabetic retinopathy: review on biomarkers of oxidative stress

    Directory of Open Access Journals (Sweden)

    Andi A. Victor

    2014-06-01

    Full Text Available Background: This study was aimed to compare the effect of laser photocoagulation (LF, intravitreal bevacizumab (IVB and combined treatments on biomarkers of oxidative stress such as aldehhyde dehidrogenase (ALDH, malondialdehyde (MDA level, superoxide dismutase (SOD activities, and vitreal vascular endothelial growth factor (VEGF on proliferative diabetic retinopathy (DR patients.Methods: In this single blind randomized clinical trial, 72 eyes from 69 cases of proliferative DR in Cipto Mangunkusumo Hospital between February 2011 - June 2013 were randomized into 4 groups : 1 control (n = 18; 2 LF pre-vitrectomy (n = 18; 3 IVB pre-vitrectomy (n = 18; and 4 combined IVB and LF pre-vitrectomy (n = 18. One-way ANOVA was used to compare oxidative stress parameters in the four groups.Results: There were no statistically significant differences in the average plasma ALDH activity (0.034 ± 0.02; 0.027 ± 0.02; 0.025 ± 0.02; 0.031 ± 0.11 IU/mg protein; p = 0.66, vitreal MDA level (1.661 ± 1.21; 1.557 ± 1.32; 1.717 ± 1.54; 1.501 ± 1.09 nmol/mL; p = 0.96 and SOD activity (0.403 ± 0.50; 0.210 ± 0.18; 0.399 ± 0.49; 0.273 ± 0.32 U/mL; p = 0.38 among these four groups, respectively. However, the VEGF vitreal level (pg/mL showed a statistically significant difference (0.356 ± 0.60; 0.393 ± 0.45; 0.150 ± 0.24; 0.069 ± 0.13; p = 0.05. The VEGF level in combination group was five times lower than the control group (p = 0.05.Conclusion: Combined treatments of DR by IVB and LF were correlated with lower vitreal MDA and plasma VEGF level, but did not have any effect on plasma ALDH and vitreal SOD in proliferative DR. Combined treatments with IVB and LF are recommended for the management of proliferative DR patients.  

  20. Effect of adding oral calcium dobesilate to laser photocoagulation on the macular thickness in patients with diabetic macular edema: a randomized clinical trial.

    Science.gov (United States)

    Feghhi, Mostafa; Farrahi, Fereydoun; Abbaspour, Mohammadreza; Takhtaeian, Akbar

    2014-12-01

    To evaluate the effect of oral calcium dobesilate (Doxium) on macular thickness in clinically significant macular edema (CSME). Overall, 71 eyes of 40 patients with non-proliferative diabetic retinopathy and clinically significant macular edema were included. All patients were received laser treatment for macular edema. Coherence optical tomography was used to determine the retinal thickness. Patients were randomized into two groups: group A received three Doxium capsule daily and group B received three placebo capsule daily for six months. The mean macular thickness before and after treatment in the group A was 340 and 257 micrometers respectively (24.5% reduced), and in the group B was 336 micrometers and 263 micrometers respectively (21.5% reduced). Macular thickness significantly decreased after treatment in both groups and the reduction in group A is higher but the difference of reduction between the two groups was not statistically significant (P>0.05). In respect to the effect of adding oral Doxium to Laser Photocoagulation on the macular thickness in patients with diabetic macular edema, this study showed no statistically significant difference between Doxium and placebo.

  1. Effect of Adding Oral Calcium Dobesilate to Laser Photocoagulation on the Macular Thickness in Patients with Diabetic Macular Edema: A Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Mostafa Feghhi

    2014-12-01

    Full Text Available Purpose: To evaluate the effect of oral calcium dobesilate (Doxium on macular thickness in clinically significant macular edema (CSME. Methods: Overall, 71 eyes of 40 patients with non-proliferative diabetic retinopathy and clinically significant macular edema were included. All patients were received laser treatment for macular edema. Coherence optical tomography was used to determine the retinal thickness. Patients were randomized into two groups: group A received three Doxium capsule daily and group B received three placebo capsule daily for six months. Results: The mean macular thickness before and after treatment in the group A was 340 and 257 micrometers respectively (24.5% reduced, and in the group B was 336 micrometers and 263 micrometers respectively (21.5% reduced. Macular thickness significantly decreased after treatment in both groups and the reduction in group A is higher but the difference of reduction between the two groups was not statistically significant (P>0.05. Conclusion: In respect to the effect of adding oral Doxium to Laser Photocoagulation on the macular thickness in patients with diabetic macular edema, this study showed no statistically significant difference between Doxium and placebo.

  2. Scattering theory

    CERN Document Server

    Friedrich, Harald

    2016-01-01

    This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...

  3. Magnetic Resonance-Guided Interstitial Laser Photocoagulation for the Treatment of Breast Cancer

    National Research Council Canada - National Science Library

    Harms, Steven

    1998-01-01

    ... by most diagnostic imaging methods, MR imaging is used to define tumor margins and extent. Our research group has developed a high-contrast, high-resolution method for MR imaging of the breast, called RODEO...

  4. Survival Rate without Brain Abnormalities on Postnatal Ultrasonography among Monochorionic Twins after Fetoscopic Laser Photocoagulation for Selective Intrauterine Growth Restriction with Concomitant Oligohydramnios.

    Science.gov (United States)

    Ishii, Keisuke; Wada, Seiji; Takano, Mayumi; Nakata, Masahiko; Murakoshi, Takeshi; Sago, Haruhiko

    2018-02-20

    We aimed to clarify the survival rate without brain abnormalities (BA) after fetoscopic laser photoco-agulation (FLP) for monochorionic diamniotic twin gestations (MCDA) with selective intrauterine growth restriction (sIUGR) accompanied by abnormal umbilical artery (UA) Doppler waveforms and isolated oligohydramnios in the sIUGR twin. This retrospective study included 52 cases that underwent FLP. The main outcome was survival rate without BA of the twins at age 28 days. BA was defined as severe intraventricular hemorrhage and periventricular leukomalacia on postnatal ultrasonography. Median gestational age at FLP was 20 (16-24) weeks. Ten cases were classified as type III based on Doppler for the UA. For all cases, including 20 cases of anterior placenta, FLP was completed without major intraoperative complications. Amnioinfusion was required in 49 cases for better fetoscopic visualization. Fetal loss occurred in 29 sIUGR twins and two larger twins, whereas one larger twin experienced neonatal death. Survival rates without BA were 44% (n = 23) for sIUGR twins and 94% (n = 49) for the larger twins. FLP for MCDA with sIUGR presenting with oligohydramnios in the sIUGR twin might be considered a prenatal treatment option. © 2018 S. Karger AG, Basel.

  5. Scattering of electromagnetic waves by obstacles

    CERN Document Server

    Kristensson, Gerhard

    2016-01-01

    The main purpose of Scattering of Electromagnetic Waves by Obstacles is to give a theoretical treatment of the scattering phenomena, and to illustrate numerical computations of some canonical scattering problems for different geometries and materials.

  6. Evaluating the Efficiency of the Device in Shielding Scattered Radiation during Treatment of Carcinoma of the Penis

    Energy Technology Data Exchange (ETDEWEB)

    Gim, Yang Soo; Lee, Sun Young; Lim, Suk Gun; Gwak, Geun Tak; Park, Ju Gyeong; Lee, Seung Hoon; Hwang, Ho In; Cha, Sook Yong [Dept. of Radiation Oncology, Chonbuk National University Hoispital, Jeonju (Korea, Republic of)

    2009-03-15

    We evaluated the device that was created for maintaining the patient's setup and protecting the testicles from scattered radiation during treatment of carcinoma of the penis. The phantom testicles were made of vaseline cotton gauze and the device consisted of 5 mm of acryl box and 4 mm of lead shielding. 3 x 3 cm{sup 2}, 4 x 4 cm{sup 2}, 5 x 5 cm{sup 2}, 6 x 6 cm{sup 2}, 7 x 7 cm{sup 2} field sizes were used for this study and measurement was made at 4, 5, 6, 7, 8, 10 cm from the lower edge of the field for 10 times with lead shielding and without the shielding respectively. 200 cGy was delivered using 6 MV photons. The scatted radiation without lead shielding at 4, 5, 6, 7, 8, 10 cm from the lower edge of the field were 14.8-4.7 cGy with 3 x 3 cm{sup 2}, 15.7-5.2 cGy with 4 x 4 cm{sup 2}, 17.6-5.5 cGy with 5 x 5 cm{sup 2}, 19.9-6.6 cGy with 6 x 6 cm{sup 2}, 22.2-7.6 cGy with 7 x 7 cm{sup 2} and the measured dose without lead shielding were 7.1-2.6 cGy with 3 x 3 cm{sup 2}, 8.9-3.6 cGy with 4 x 4 cm{sup 2}, 12.3-4.8 cGy with 5 x 5 cm{sup 2}, 14.6-5.0 cGy with 6 x 6 cm{sup 2} and 21.1-6.4 cGy with 7 x 7 cm{sup 2}. As shown above, the scatted radiation decreased after using lead shielding. Depending of the range of field sizes, the resulting difference between without shielding values and with shielding values were: 7.8-1.1 cGy at 4 cm, 5.1-1.2 cGy at 5 cm, 3.8-1.1 cGy at 6 cm, 3.4-1.7 cGy at 7 cm, 2.8-1.7 cGy at 8 cm, 2.4-2.5 cGy at 9 cm and 2.1-1.8 cGy at 10 cm. In the situation as described above, the range in values depending on the distance was 7.8-1.1 cGy with 3 x 3 cm{sup 2}, 6.9-1.6 cGy with 4 x 4 cm{sup 2}, 5.3-0.8 cGy with 5 x 5 cm{sup 2}, 5.3-1.5 cGy with 6 x 6 cm{sup 2} and 1.1-1.8 cGy with 7 x 7 cm{sup 2}. Using the device we created to shield the testicles from scattered radiation during treatment of carcinoma of the penis, we have found that scattered radiation to the testicles is decreased by the phantom testicles, and by increasing the distance

  7. Hypofractionated passively scattered proton radiotherapy for low- and intermediate-risk prostate cancer is not associated with post-treatment testosterone suppression

    Energy Technology Data Exchange (ETDEWEB)

    Kil, Whoon Jong; Nichols, Romaine C. Jr. [Dept. of Radiation Oncology, Univ. of Florida, Gainesville (United States); Univ. of Florida Proton Therapy Inst., Jacksonville (United States)], e-mail: rnichols@floridaproton.org; And others

    2013-04-15

    Background: To investigate post-treatment changes in serum testosterone in low- and intermediate-risk prostate cancer patients treated with hypofractionated passively scattered proton radiotherapy. Material and methods: Between April 2008 and October 2011, 228 patients with low- and intermediate-risk prostate cancer were enrolled into an institutional review board-approved prospective protocol. Patients received doses ranging from 70 Cobalt Gray Equivalent (CGE) to 72.5 CGE at 2.5 CGE per fraction using passively scattered protons. Three patients were excluded for receiving androgen deprivation therapy (n = 2) or testosterone supplementation (n = 1) before radiation. Of the remaining 226 patients, pretreatment serum testosterone levels were available for 217. Of these patients, post-treatment serum testosterone levels were available for 207 in the final week of treatment, 165 at the six-month follow-up, and 116 at the 12-month follow-up. The post-treatment testosterone levels were compared with the pretreatment levels using Wilcoxon's signed-rank test for matched pairs. Results: The median pretreatment serum testosterone level was 367.7 ng/dl (12.8 nmol/l). The median changes in post-treatment testosterone value were as follows: +3.0 ng/dl (+0.1 nmol/l) at treatment completion; +6.0 ng/dl (+0.2 nmol/l) at six months after treatment; and +5.0 ng/dl (0.2 nmol/l) at 12 months after treatment. None of these changes were statistically significant. Conclusion: Patients with low- and intermediate-risk prostate cancer treated with hypofractionated passively scattered proton radiotherapy do not experience testosterone suppression. Our findings are consistent with physical measurements demonstrating that proton radiotherapy is associated with less scatter radiation exposure to tissues beyond the beam paths compared with intensity-modulated photon radiotherapy.

  8. Effects of Laser Physical Parameters on Lesion Size in Retinal Photocoagulation Surgery: Clinical OCT and Experimental Study

    Directory of Open Access Journals (Sweden)

    Soleimani A.

    2017-12-01

    Full Text Available Introduction: The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT, fundus camera, physical eye model and computer simulation in a clinical study. Materials and Methods: Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants. Lesion size was measured for spot sizes 50 and 100 μm, with 100 and 150 mW laser power, and pulse duration 50 and 100 ms by OCT. Artificial eye and Zemax-optical design software were used with the same laser parameters. Results: Appearance of OCT and fundus images showed direct relationship between retina burn size and lesion intensity with exposure time and power and also reverse relationship with laser spot size. Compared to red wavelength, burn size and lesion intensity increased in green wavelength. On the other hand, results from physical eye model were the same as clinical examination shown. Laser spot size in retina with Zemax simulation demonstrated that red wavelength was greater than green one. Conclusion: This study showed shorter pulses provide decrease in duration of laser surgery with significantly reduced pain. Results and calculations described in this article can help clinicians adjusting the required total coagulated area, the number of lesions and pattern density.

  9. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kostorz, G. [Eidgenoessische Technische Hochschule, Angewandte Physik, Zurich (Switzerland)

    1996-12-31

    While Bragg scattering is characteristic for the average structure of crystals, static local deviations from the average lattice lead to diffuse elastic scattering around and between Bragg peaks. This scattering thus contains information on the occupation of lattice sites by different atomic species and on static local displacements, even in a macroscopically homogeneous crystalline sample. The various diffuse scattering effects, including those around the incident beam (small-angle scattering), are introduced and illustrated by typical results obtained for some Ni alloys. (author) 7 figs., 41 refs.

  10. [Analysis of choroidal thickness in AP-ROP, threshold disease and ROP without laser photocoagulation].

    Science.gov (United States)

    Gökgöz-Özisik, G; Akkoyun, Imren; Oto, S; Bayar, S A; Tarcan, A; Kayhan, Z; Yilmaz, G

    2016-01-01

    Enhanced depth imaging (EDI) and spectral domain optical coherence tomography (SD-OCT) provide high-definition cross-sectional images of the choroid. Information on alterations in choroidal thickness (CT) after laser photocoagulation (LC) in aggressive posterior retinopathy of prematurity (APROP) and threshold disease (TD) is rare. A total of 75 eyes were retrospectively analyzed in 4 groups. Groups 1 and 2 included patients with APROP and TD, respectively, who underwent LC. Group 3 included ROP children who did not undergo LC and group 4 included full-term children. Infants aged ≥4 EDI-OCT, visual acuity (VA), spherical equivalent (SE), anterior segment and fundus examination, axial lenght (AXL) were included. The results of SFCT, VA and SE at the age of ≥ 4 < 7 years, AXL, gestational age (GA), birth weight (BW) and age at examination were compared between the groups. Potential risk factors (GA, BW, SE, AXL and SFCT) influencing visual acuity were evaluated by using multivariate linear regression analysis. The results of SFCT and AXL were not significantly different between groups 2 and 3 or between groups 3 and 4. There was a significant difference between the other groups for SFCT and AXL and VA was significantly different between all groups. The SE was not significantly different between groups 3 and 4 but there was a significant difference for SE, BW and GA between the groups. Age at examination was not significantly different between the groups. Multivariate linear regression analysis revealed SFCT for groups 1 and 2, GA for group 3 and GA, SFCT and AXL for group 4 as independent risk factors influencing visual acuity. The regression model used for groups 1-4 explains the variation of the dependent risk factor LogMar VA for groups 1-4 with 31.2 %, 43.5 %, 9.6 % and 69.4 %, respectively. These values expressed in percentage demonstrate that even more predictors may influence the dependent factor LogMar VA than evaluated in the study.

  11. Efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity Eficácia e segurança da fotocoagulação com laser verde na retinopatia da prematuridade limiar

    Directory of Open Access Journals (Sweden)

    Rodrigo Pessoa Cavalcanti Lira

    2008-02-01

    Full Text Available PURPOSE: To report the efficacy and safety of green laser photocoagulation for threshold retinopathy of prematurity (ROP. METHODS: We reviewed the clinical records of the neonates who had undergone green laser photocoagulation for threshold ROP at the Federal University of Pernambuco in Brazil between January 2004 and January 2006. All procedures were conducted with local anesthetic drops. The neonates were monitored throughout the procedure by a neonatologist. A frequency-doubled solid state laser, diode-pumped, with 532 nm wavelength was used. The presence of tunica vasculosa lentis or cataract were excluded before laser treatment. The following preoperative data were obtained for each patient: age, birth weight and the grade of ROP. Postoperative data included complications associated with the laser treatment, grade of ROP and evaluation whether further surgery was necessary due to failure of laser photocoagulation. RESULTS: Twenty-two neonates underwent photocoagulation with green laser for threshold ROP. A total of 31 eyes were included in the study. The mean gestational age was 30 ± 3 weeks and the mean birth weight was 1120 ± 490 g. Regression of the disease after laser therapy was observed in 30 eyes (96.7%. Despite treatment one eye presented stage 4A. Only 7 eyes required repetitive laser therapy. No adverse effects such as burning anterior segment tissues or bleeding in the anterior chamber occurred. No posterior segment side-effects were observed. Cataract formation was not observed at the last follow-up examination. CONCLUSIONS: Green laser photocoagulation remains an effective and safe alternative to red laser photocoagulation and to cryotherapy in the treatment of threshold ROP.OBJETIVOS: Avaliar a eficácia e segurança da fotocoagulação com laser verde na retinopatia da prematuridade (ROP limiar. MÉTODOS: Foram revisados prontuários dos neonatos submetidos à fotocoagulação com laser verde para ROP limiar, na

  12. Monte Carlo simulation and parameterized treatment on the effect of nuclear elastic scattering in high-energy proton radiography

    Science.gov (United States)

    Xu, Hai-Bo; Zheng, Na

    2015-07-01

    A version of Geant4 has been developed to treat high-energy proton radiography. This article presents the results of calculations simulating the effects of nuclear elastic scattering for various test step wedges. Comparisons with experimental data are also presented. The traditional expressions of the transmission should be correct if the angle distribution of the scattering is Gaussian multiple Coulomb scattering. The mean free path (which depends on the collimator angle) and the radiation length are treated as empirical parameters, according to transmission as a function of thickness obtained by simulations. The results can be used in density reconstruction, which depends on the transmission expressions. Supported by NSAF (11176001) and Science and Technology Developing Foundation of China Academy of Engineering Physics (2012A0202006)

  13. Thomson Scattering

    NARCIS (Netherlands)

    Donne, A. J. H.

    1994-01-01

    Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is

  14. An examination of errors in computed water-leaving radiances due to a simplified treatment of water Raman scattering effects

    Science.gov (United States)

    Bismarck, Jonas von; Fischer, Jürgen

    2013-05-01

    Studies in the past have shown that solar shortwave radiation that has been Raman scattered in the ocean, and therefore undergone a wavelength shift, can contribute significantly to the signals observed by remote sensing satellites. While radiative transfer models that qualitatively approximate the effect of water Raman scattering on the water leaving irradiance have been available for a while, we have developed a new version of the radiative transfer code MOMO, which enables the accurate and fully angle resolved inclusion of inelastic scattering sources, and therefore allows detailed quantitative analyses of the effect on the light field in the ocean-atmosphere system. This article focuses on a study performed with this new model on the impact of azimuthally averaging the Raman scattering phase function, which is done in some RT models and significantly decreases computation time, on the water-leaving radiance. At the request of the authors and Proceedings Editors the above article has been updated to include a number of post-publication amendments. Changes made to the previously published article are detailed in the pages attached to the end of the updated article PDF file. The updated article was re-published on 15 August 2013.

  15. Ultrastructure of Bruch's membrane after krypton laser photocoagulation. II. Repair of Bruch's membrane and the role of macrophages.

    Science.gov (United States)

    Pollack, A; Korte, G E; Heriot, W J; Henkind, P

    1986-09-01

    The accompanying ultrastructural study showed that ophthalmoscopically white krypton laser photocoagulation in rats is followed by cellular invasion causing breakdown of Bruch's membrane (BM). We have expanded these observations, using scanning electron microscopy, transmission electron microscopy, and high-voltage transmission electron microscopy to describe the healing process. The repair of BM involves regenerating retinal pigment epithelial cells and choriocapillaris (CC) that form new basement membranes and fibroblasts that secrete collagen and elastin. The reformation of the CC is also associated with subretinal neovascularization. The involvement of macrophages was evident throughout the process of BM repair and formation of new vessels. We propose that the macrophages act as a common factor linking the diverse diseases associated with choroidal subretinal neovascularization, deduced from our evaluation of the healing process and the reformation of choriocapillaris.

  16. Prenatal spontaneous disruption of the dividing membrane in monochorionic diamniotic twins detected at the time of fetoscopic laser photocoagulation.

    Science.gov (United States)

    Yoshimura, Kazuaki; Aiko, Yukiyo; Inagaki, Hirohide; Nakata, Masahiko; Hachisuga, Toru

    2009-12-01

    Spontaneous antepartum rupture of the dividing membrane occurring in monochorionic diamniotic twins (MD twin) is an extremely rare complication and difficult to diagnose prenatally. We present a case of pseudo-monoamniotic twins derived from an MD twin gestation, which was suspected by ultrasound and was confirmed by antepartum fetoscopy. A 28-year-old woman, gravida 1, para 1 at 24 weeks of gestation was referred because of suspected polyhydroamnios in an MD twin. Ultrasound suggested twin-twin transfusion syndrome stage III, spontaneous rupture of the dividing membranes and cord entanglement. Fetoscopic laser photocoagulation (FLP) was performed using the Nd:YAG laser on 12 placental vascular connections. Fetoscopy revealed the spontaneous rupture of the dividing membrane and cord entanglement. The remainder of the pregnancy was managed as a monoamniotic twin gestation. Elective cesarean section was performed at 32 weeks of gestation following antenatal steroids and concordantly grown healthy male infants were delivered.

  17. Effects of argon (green) laser treatment of soft drusen in early age-related maculopathy: a 6 month prospective study.

    Science.gov (United States)

    Frennesson, I C; Nilsson, S E

    1995-01-01

    AIM--To evaluate whether perifoveal laser photocoagulation of soft drusen reduces the total area occupied by drusen. METHOD--In a prospective, randomised study, 20 patients (mean age 71.3 (SD 7.7) years) with early age-related maculopathy (ARM) in the form of soft drusen and pigmentary changes and with good visual acuity (0.94 (0.09)) were treated with argon green laser photocoagulation. Mild laser burns (200 microns) were placed within a temporal horseshoe-shaped area, extending from a distance of no less than 500 microns from the centre of the fovea to the vascular arcades. They were placed on the drusen and scattered over areas where no drusen were present. Fundus colour photography and fluorescein angiography were performed at study entry as well as after 3 and 6 months. Nineteen age-matched patients (68.5 (6.2) years) with soft drusen maculopathy (visual acuity 0.95 (0.10)) were followed as a control group. Using a computer system, the area occupied by drusen was determined as a portion of the total area of a circle with a radius corresponding to 1250 microns in the fundus for the angiograms and 2500 microns for the colour photographs, respectively. At study entry, the mean area occupied by drusen in the treatment group was not significantly (p > 0.5-0.7) different from that of the control group. RESULTS--The mean drusen area of the angiograms and fundus colour photographs in the treated group decreased significantly from 19.3% to 13.8% (p = 0.002) and from 7.84% to 5.02% (p = 0.005), respectively. In the untreated group, the mean area occupied by drusen increased significantly from 17.4% to 20.4% (p = 0.030) and from 8.33% to 9.23% (p = 0.002), respectively. No significant changes in visual acuity (p > 0.05-0.5) or in visual fields (p > 0.05-0.3) occurred in either of the two groups during 6 months. CONCLUSION--The study suggests that the area occupied by soft drusen in patients with early ARM decreases after perifoveal laser photocoagulation but increases in

  18. Critical scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics

    1996-12-31

    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.

  19. Efficacy of patterned scan laser in treatment of macular edema and retinal neovascularization

    Directory of Open Access Journals (Sweden)

    Dimple Modi

    2009-08-01

    Full Text Available Dimple Modi, Paulpoj Chiranand, Levent AkdumanSaint Louis University School of Medicine, Department of Ophthalmology, Saint Louis University Eye Institute, St. Louis, Missouri, USAPurpose: To analyze the benefits, efficacy, and complications of the PASCAL® photocoagulation laser system (OptiMedica, Santa Clara, CA, USA in patients treated at our institution.Methods: We conducted a retrospective chart review of 19 patients (28 eyes who underwent laser treatment using the PASCAL® photocoagulation system from November 2006 to November 2007. These 28 eyes were divided into two groups; group 1 eyes underwent macular grid laser and group 2 eyes underwent panretinal photocoagulation. Treatment was performed for macular edema or for iris or retinal neovascularization. Outcomes measured included best-corrected visual acuity (BCVA, efficacy of laser treatment, complications, duration of the procedure, and pain perception, which were noted in the charts for panretinal treatments.Results: Follow-up was 5.9 ± 2.6 months for group 1 and 5.9 ± 4.0 months for group 2. In group 1, 9/28 eyes required a second treatment for remaining edema. BCVA was stable or better in 66% (14/21 and average central foveal thickness on ocular coherence tomography improved in 71% (15/21. Time to completion for a number of laser patterns for grid photocoagulation was felt to be too long for completing the total pattern safely, although we have not noted any related complications. In group 2, the neovascularization regressed at least partially in 3/7 patients. Patient-reported pain perception was 3.6 on a scale of 1 to 10 for group 2. Occasional hemorrhages occurred secondary to irregular laser uptake at different spots in the patterns. We observed no visual outcome consequences because of these hemorrhages during follow-up.Conclusions: Retinal photocoagulation by the PASCAL® laser has comparable efficacy to historical results with conventional retinal photocoagulation in short

  20. Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.

  1. Dispersion Decay and Scattering Theory

    CERN Document Server

    Komech, Alexander

    2012-01-01

    A simplified, yet rigorous treatment of scattering theory methods and their applications Dispersion Decay and Scattering Theory provides thorough, easy-to-understand guidance on the application of scattering theory methods to modern problems in mathematics, quantum physics, and mathematical physics. Introducing spectral methods with applications to dispersion time-decay and scattering theory, this book presents, for the first time, the Agmon-Jensen-Kato spectral theory for the Schr?dinger equation, extending the theory to the Klein-Gordon equation. The dispersion decay plays a crucial role i

  2. Synchrotron X-ray Scattering Analysis of the Interaction Between Corn Starch and an Exogenous Lipid During Hydrothermal Treatment

    Energy Technology Data Exchange (ETDEWEB)

    E Hernandez-Hernandez; C Avila-Orta; B Hsiao; j Castro-Rosas; J Gallegos-Infante; J Morales-Castro; L Ochoa-Martinez; C Gomez-Aldapa

    2011-12-31

    Lipids have an important effect on starch physicochemical properties. There exist few reports about the effect of exogenous lipids on native corn starch structural properties. In this work, a study of the morphological, structural and thermal properties of native corn starch with L-alpha-lysophosphatidylcholine (LPC, the main phospholipid in corn) was performed under an excess of water. Synchrotron radiation, in the form of real-time small and wide-angle X-ray scattering (SAXS/WAXS), was used in order to track structural changes in corn starch, in the presence of LPC during a heating process from 30 to 85 C. When adding LCP, water absorption decreased within starch granule amorphous regions during gelatinization. This is explained by crystallization of the amylose-LPC inclusion complex during gelatinization, which promotes starch granule thermal stability at up to 95 C. Finally, a conceptual model is proposed for explaining the formation mechanism of the starch-LPC complex.

  3. Reprint of Testing scattering matrices: a compendium of recipes

    NARCIS (Netherlands)

    Hovenier, J.W.; van der Mee, C.V.M.

    2010-01-01

    Scattering matrices describe the transformation of the Stokes parameters of a beam of radiation upon scattering of that beam. The problems of testing scattering matrices for scattering by one particle and for single scattering by an assembly of particles are addressed. The treatment concerns

  4. On the effect of thermal treatment and hydrogen vibrational dynamics in sodium alanates: An inelastic neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Albinati, A., E-mail: Alberto.Albinati@unimi.it [Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Universita degli Studi di Milano, via G. Venezian 21, 20133 Milan (Italy); Colognesi, D. [Consiglio Nazionale delle Ricerche, Istituto di Sistemi Complessi, via Madonna del Piano 10, 50019 Sesto Fiorentino (Finland) (Italy); Georgiev, P.A. [Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Universita degli Studi di Milano, via G. Venezian 21, 20133 Milan (Italy); Jensen, C.M. [Department of Chemistry, University of Hawaii, Honolulu, HI 96822 (United States); Ramirez-Cuesta, A.J. [ISIS facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer High resolution INS spectra of thermally treated NaAlH{sub 4} and Na{sub 3}AlH{sub 6}. Black-Right-Pointing-Pointer Detailed spectral features assignments based on high quality DFT(GGA) calculations. Black-Right-Pointing-Pointer Treated materials spectra are described as sum of the corresponding reactants and products. Black-Right-Pointing-Pointer The existence of AlH{sub 3} and AlH{sub 5}{sup 2-} species is not observed in the bulk, under equilibrium. - Abstract: We have measured inelastic neutron scattering (INS) spectra from Ti-doped polycrystalline alanates (NaAlH{sub 4} and Na{sub 3}AlH{sub 6}), at low temperature, in the energy transfer range 3-500 meV, both for thermally treated and untreated samples. From the spectral range corresponding to the fundamental vibrational bands of these aluminohydrides, accurate one-phonon spectra and hydrogen-projected densities of phonon states have been extracted and analyzed using ab initio lattice dynamics calculations. Satisfactory agreement has been found for the untreated samples. In the case of thermally treated samples, due to thermal decomposition, different ionic species are present and the sample composition could be quantitatively evaluated. No evidence for the existence of intermediate species such as AlH{sub 3} or AlH{sub 5}{sup 2-} has been found.

  5. Hydrogen treatment-improved uniform deposition of Ag nanoparticles on ZnO nanorod arrays and their visible-light photocatalytic and surface-enhanced Raman scattering properties.

    Science.gov (United States)

    Lin, Sio-Le; Hsu, Kai-Chih; Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2013-07-16

    ZnO nanorod arrays were synthesized by chemical bath deposition. After heat treatment in hydrogen or air, Ag nanoparticles were deposited on ZnO nanorod arrays by photo-reduction method. The size of Ag nanoparticles as well as the surface morphology, structure, composition, and optical property of ZnO nanorod arrays before and after the deposition of Ag nanoparticles were characterized by SEM, XRD, EDS, and UV/VIS/NIR spectrophotometer. As compared to the samples with heat treatment in air or without heat treatment, the ZnO nanorod arrays after heat treatment in hydrogen allowed Ag nanoparticles to be deposited more uniformly, densely, and numerously. Also, they exhibited higher efficiency for the visible light-driven photocatalytic degradation of Rhodamine 6G (R6G) dye. The effects of the amount of Ag nanoparticles, initial dye concentration, and temperature on the photocatalytic degradation efficiency were investigated. Furthermore, they also exhibited better surface-enhanced Raman scattering property for the detection of R6G dyes.

  6. Intravitreal bevacizumab injection alone or combined with triamcinolone versus macular photocoagulation in bilateral diabetic macular edema; application of bivariate generalized linear mixed model with asymmetric random effects in a subgroup of a clinical trial

    Directory of Open Access Journals (Sweden)

    Mehdi Yaseri

    2014-01-01

    Full Text Available Purpose: To compare the efficacy of intravitreal bevacizumab (IVB injection alone or with intravitreal triamcinolone acetonide (IVB/IVT versus macular photocoagulation (MPC in bilateral diabetic macular edema (DME. Methods: In this study we revisited data from a subset of subjects previously enrolled in a randomized clinical trial. The original study included 150 eyes randomized to three treatment arms: 1.25 mg IVB alone, combined injection of 1.25 mg IVB and 2 mg IVT, and focal or modified grid MPC. To eliminate the possible effects of systemic confounders, we selected fellow eyes of bilaterally treated subjects who had undergone different treatments; eventually 30 eyes of 15 patients were re-evaluated at baseline, 6, 12, 18, and 24 months. Using mixed model analysis, we compared the treatment protocols regarding visual acuity (VA and central macular thickness (CMT. Results: Improvement in VA in the IVB group was significantly greater compared to MPC at months 6 and 12 (P = 0.037 and P = 0.035, respectively but this difference did not persist thereafter up to 24 months. Other levels of VA were comparable at different follow-up intervals (all P > 0.05. The only significant difference in CMT was observed in favor of the IVB group as compared to IVB/IVT group at 24 months (P = 0.048. Conclusion: Overall VA was superior in IVB group as compared to MPC up to 12 months. Although the IVB group showed superiority regarding CMT reduction over 24 months as compared to IVB/IVT group, it was comparable to the MPC group through the same period of follow up.

  7. Intravitreal bevacizumab injection alone or combined with triamcinolone versus macular photocoagulation in bilateral diabetic macular edema; application of bivariate generalized linear mixed model with asymmetric random effects in a subgroup of a clinical trial.

    Science.gov (United States)

    Yaseri, Mehdi; Zeraati, Hojjat; Mohammad, Kazem; Soheilian, Masoud; Ramezani, Alireza; Eslani, Medi; Peyman, Gholam A

    2014-01-01

    To compare the efficacy of intravitreal bevacizumab (IVB) injection alone or with intravitreal triamcinolone acetonide (IVB/IVT) versus macular photocoagulation (MPC) in bilateral diabetic macular edema (DME). In this study we revisited data from a subset of subjects previously enrolled in a randomized clinical trial. The original study included 150 eyes randomized to three treatment arms: 1.25 mg IVB alone, combined injection of 1.25 mg IVB and 2 mg IVT, and focal or modified grid MPC. To eliminate the possible effects of systemic confounders, we selected fellow eyes of bilaterally treated subjects who had undergone different treatments; eventually 30 eyes of 15 patients were re-evaluated at baseline, 6, 12, 18, and 24 months. Using mixed model analysis, we compared the treatment protocols regarding visual acuity (VA) and central macular thickness (CMT). Improvement in VA in the IVB group was significantly greater compared to MPC at months 6 and 12 (P = 0.037 and P = 0.035, respectively) but this difference did not persist thereafter up to 24 months. Other levels of VA were comparable at different follow-up intervals (all P > 0.05). The only significant difference in CMT was observed in favor of the IVB group as compared to IVB/IVT group at 24 months (P = 0.048). Overall VA was superior in IVB group as compared to MPC up to 12 months. Although the IVB group showed superiority regarding CMT reduction over 24 months as compared to IVB/IVT group, it was comparable to the MPC group through the same period of follow up.

  8. 'A problem shared is a problem halved': success of a statewide collaborative approach to fetal therapy. Outcomes of fetoscopic laser photocoagulation for twin-twin transfusion syndrome in Victoria.

    Science.gov (United States)

    Teoh, Mark; Walker, Sue; Cole, Stephen; Edwards, Andrew

    2013-04-01

    To evaluate the performance of a collaborative fetal therapy service for treatment for twin-twin transfusion syndrome (TTTS). The Victorian Fetal Therapy Service (VFTS) was developed in 2006. It is a state-based three-centre collaborative service comprising a surgical team and clinical leadership group, designed to optimise access to, and performance of, fetoscopic procedures in Victoria. This is a prospective cohort study of VFTS patients referred for fetoscopic laser photocoagulation (FLP) for TTTS since 2006. Forty-nine consecutive women with advanced (stage 2-4) TTTS between 2006 and 2011 were included in this study. Overall survival was 67 of 98 (68%), and survival of ≥1 twin was seen in 42 of 49 pregnancies (86%). There was no difference in survival by disease stage at diagnosis (≥1 survivor: 66% (stage 2 or 3 TTTS) vs 77% (stage 4 TTTS), P = 0.44), nor by surgical era (≥1 survivor: 60% (2006-2008) vs 74% of cases (2009-2011), P = 0.21). The median gestation gained post-FLP was 10.5 weeks. These results are consistent with published series and confirm the success of a novel service delivery model for fetal therapy in Victoria. We suggest that collaborative models such as ours should be considered for fetal conditions where treatment is complex and the total number of cases is small to ensure a consistent approach to assessment, management and follow-up of patients and to optimise training and research opportunities. © 2013 The Authors ANZJOG © 2013 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

  9. Fabrication and characterization of homogeneous surface-enhanced Raman scattering substrates by single pulse UV-laser treatment of gold and silver films.

    Science.gov (United States)

    Christou, Konstantin; Knorr, Inga; Ihlemann, Jürgen; Wackerbarth, Hainer; Beushausen, Volker

    2010-12-07

    The fabrication of SERS-active substrates, which offer high enhancement factors as well as spatially homogeneous distribution of the enhancement, plays an important role in the expansion of surface-enhanced Raman scattering (SERS) spectroscopy to a powerful, quantitative, and noninvasive measurement technique for analytical applications. In this paper, a novel method for the fabrication of SERS-active substrates by laser treatment of 20, 40, and 60 nm thick gold and of 40 nm thick silver films supported on quartz glass is presented. Single 308 nm UV-laser pulses were applied to melt the thin gold and silver films. During the cooling process of the noble metal, particles were formed. The particle size and density were imaged by atomic force microscopy. By varying the fluence, the size of the particles can be controlled. The enhancement factors of the nanostructures were determined by recording self-assembled monolayers of benzenethiol. The intensity of the SERS signal from benzenethiol is correlated to the mean particle size and thus to the fluence. Enhancement factors up to 10(6) with a high reproducibility were reached. Finally we have analyzed the temperature dependence of the SERS effect by recording the intensity of benzenethiol vibrations from 300 to 120 K. The temperature dependence of the SERS effect is discussed with regard to the metal properties.

  10. Incorporating quantitative single photon emission computed tomography into radiation therapy treatment planning for lung cancer: impact of attenuation and scatter correction on the single photon emission computed tomography-weighted mean dose and functional lung segmentation.

    Science.gov (United States)

    Yin, Lingshu; Shcherbinin, Sergey; Celler, Anna; Thompson, Anna; Fua, Tsien-Fei; Liu, Mitchell; Duzenli, Cheryl; Gill, Brad; Sheehan, Finbar; Powe, John; Worsley, Daniel; Marks, Lawrence; Moiseenko, Vitali

    2010-10-01

    To assess the impact of attenuation and scatter corrections on the calculation of single photon emission computed tomography (SPECT)-weighted mean dose (SWMD) and functional volume segmentation as applied to radiation therapy treatment planning for lung cancer. Nine patients with lung cancer underwent a SPECT lung perfusion scan. For each scan, four image sets were reconstructed using the ordered subsets expectation maximization method with attenuation and scatter corrections ranging from none to a most comprehensive combination of attenuation corrections and direct scatter modeling. Functional volumes were segmented in each reconstructed image using 10%, 20%, …, 90% of maximum SPECT intensity as a threshold. Systematic effects of SPECT reconstruction methods on treatment planning using functional volume were studied by calculating size and spatial agreements of functional volumes, and V(20) for functional volume from actual treatment plans. The SWMD was calculated for radiation beams with a variety of possible gantry angles and field sizes. Functional volume segmentation is sensitive to the particular method of SPECT reconstruction used. Large variations in functional volumes, as high as >50%, were observed in SPECT images reconstructed with different attenuation/scatter corrections. However, SWMD was less sensitive to the type of scatter corrections. SWMD was consistent within 2% for all reconstructions as long as computed tomography-based attenuation correction was used. When using perfusion SPECT images during treatment planning optimization/evaluation, the SWMD may be the preferred figure of merit, as it is less affected by reconstruction technique, compared with threshold-based functional volume segmentation. 2010 Elsevier Inc. All rights reserved.

  11. On scattered subword complexity

    CERN Document Server

    Kása, Zoltán

    2011-01-01

    Special scattered subwords, in which the gaps are of length from a given set, are defined. The scattered subword complexity, which is the number of such scattered subwords, is computed for rainbow words.

  12. Bidirectional optical scattering facility

    Data.gov (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

  13. [Surgical treatment of the optic disc pit maculopathy].

    Science.gov (United States)

    Krásnik, V; Strmen, P; Atefanicková, J; Ferková, S

    2007-01-01

    To evaluate long-term effects of anatomic and functional changes after the surgical treatment of the optic disc pit maculopathy in a retrospective study. Six patients with unilateral optic disc pit maculopathy were included in this study. Four were females and 2 males, age ranged from 13 to 35 years (mean, 26 years). All patients underwent the pars plana vitrectomy, internal limiting membrane peeling and the intraocular tamponade with the air-gas mixture. These 6 patients were divided into two groups: group A, the surgical treatment without aimed argon laser photocoagulation, and group B, the surgical treatment with aimed argon laser photocoagulation during 2 months after the pars plana vitrectomy. The follow-up period ranged from 41 to 73 months (mean, 53.3 months). In the group A, the best-corrected visual acuity improved by 2 and more lines (Snellen optotype) in all 3 patients. In the group B, the improvement by 2 and more lines was found out in 2 patients and the decrease by 2 lines was observed in one patient. The recurrence of the maculopathy occurred in 2 patients from the group A. In the group B, the recurrence of the maculopathy was recorded in one patient 53 months after pars plana vitrectomy and aimed argon photocoagulation. The surgical intervention by pars plana vitrectomy for the optic disc pit maculopathy improves the anatomic and functional prognosis. The suitable aimed argon laser photocoagulation after the surgical treatment in selected patients improves outcome and reduce the recurrence of the optic disc pit maculopathy.

  14. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  15. Diabetic retinopathy (treatment).

    Science.gov (United States)

    Mohamed, Quresh Amir; Ross, Adam; Chu, Colin Jonathan

    2011-05-25

    Diabetic retinopathy is the most common cause of blindness in the UK, with older people and those with worse diabetes control, hypertension, and hyperlipidaemia being most at risk. Diabetic retinopathy can cause microaneurysms, haemorrhages, exudates, changes to blood vessels, and retinal thickening. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments in people with diabetic retinopathy? What are the effects of treatments for vitreous haemorrhage? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 58 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: peripheral retinal laser photocoagulation, focal and grid laser photocoagulation for maculopathy, corticosteroids for macular oedema, vascular endothelial growth factor inhibitors, and vitrectomy for vitreous haemorrhage.

  16. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  17. Pauli Principle and Pion Scattering

    Science.gov (United States)

    Bethe, H. A.

    1972-10-01

    It is pointed out that if the Pauli principle is taken into account in the discussion of pion scattering by complex nuclei (as it ought, of course, to be) some rather implausible consequences of some earlier treatments of this problem can be avoided. (auth)

  18. Lectures in scattering theory

    CERN Document Server

    Sitenko, A G

    1971-01-01

    Lectures in Scattering Theory discusses problems in quantum mechanics and the principles of the non-relativistic theory of potential scattering. This book describes in detail the properties of the scattering matrix and its connection with physically observable quantities. This text presents a stationary formulation of the scattering problem and the wave functions of a particle found in an external field. This book also examines the analytic properties of the scattering matrix, dispersion relations, complex angular moments, as well as the separable representation of the scattering amplitude. Th

  19. A new SERS: scattering enhanced Raman scattering

    Science.gov (United States)

    Bixler, Joel N.; Yakovlev, Vladislav V.

    2014-03-01

    Raman spectroscopy is a powerful technique that can be used to obtain detailed chemical information about a system without the need for chemical markers. It has been widely used for a variety of applications such as cancer diagnosis and material characterization. However, Raman scattering is a highly inefficient process, where only one in 1011 scattered photons carry the needed information. Several methods have been developed to enhance this inherently weak effect, including surface enhanced Raman scattering and coherent anti-Stokes Raman scattering. These techniques suffer from drawbacks limiting their commercial use, such as the need for spatial localization of target molecules to a `hot spot', or the need for complex laser systems. Here, we present a simple instrument to enhance spontaneous Raman scattering using elastic light scattering. Elastic scattering is used to substantially increase the interaction volume. Provided that the scattering medium exhibits very low absorption in the spectral range of interest, a large enhancement factor can be attained in a simple and inexpensive setting. In our experiments, we demonstrate an enhancement of 107 in Raman signal intensity. The proposed novel device is equally applicable for analyzing solids, liquids, and gases.

  20. Scattering resonances in a degenerate Fermi gas

    DEFF Research Database (Denmark)

    Challis, Katharine; Nygaard, Nicolai; Mølmer, Klaus

    2009-01-01

    We consider elastic single-particle scattering from a one-dimensional trapped two-component superfluid Fermi gas when the incoming projectile particle is identical to one of the confined species. Our theoretical treatment is based on the Hartree-Fock ground state of the trapped gas and a configur......We consider elastic single-particle scattering from a one-dimensional trapped two-component superfluid Fermi gas when the incoming projectile particle is identical to one of the confined species. Our theoretical treatment is based on the Hartree-Fock ground state of the trapped gas...... and a configuration-interaction description of the excitations. We determine the scattering phase shifts for the system and predict Fano-type scattering resonances that are a direct consequence of interatomic pairing. We describe the main characteristics of the scattering resonances and make a comparison...

  1. Oral vascular malformations: laser treatment and management

    Science.gov (United States)

    Romeo, U.; Rocchetti, F.; Gaimari, G.; Tenore, G.; Palaia, G.; Lo Giudice, G.

    2016-03-01

    Vascular malformations are a very heterogeneous group of circulatory system's diseases that can involve different kind of vessels: arterial, venous or lymphatic ones. Many treatments, such as conventional surgery, embolization, steroid therapy and laser therapy, are available for vascular lesions. The laser approach relies more therapeutic techniques: the transmucosal thermophotocoagulation, intralesional photocoagulation, the excisional biopsy. Today laser is demonstrated to be the gold standard technique to treat vascular lesions that allows a safe and efficient treatment and a lower post-operative healing time. The only disadvantage is the risk of carbonization that could be avoided by using the multiple-spot single pulsed wave technique.

  2. Extension and applications of switching model: Range theory, multiple scattering model of Goudsmit-Saunderson, and lateral spread treatment of Marwick-Sigmund

    Science.gov (United States)

    Ikegami, Seiji

    2017-09-01

    The switching model (PSM) developed in the previous paper is extended to obtain an ;extended switching model (ESM). In the ESM, the mixt electronic-and-nuclear energy-loss region, in addition to the electronic and nuclear energy-loss regions in PSM, is taken into account analytically and appropriately. This model is combined with a small-angle multiple scattering range theory considering both nuclear and electronic stopping effects developed by Marwick-Sigmund and Valdes-Arista to formulate a improved range theory. The ESM is also combined with the multiple scattering theory with non-small angle approximation by Goudsmit-Saunderson. Furthermore, we applied ESM to lateral spread model of Marwick-Sigmund. Numerical calculations of the entire distribution functions including one of the mixt region are roughly and approximately possible. However, exact numerical calculation may be impossible. Consequently, several preliminary numerical calculations of the electronic, mixt, and nuclear regions are performed to examine their underlying behavior with respect to the incident energy, the scattering angle, the outgoing projectile intensity, and the target thickness. We show the numerical results not only of PSM and but also of ESM. Both numerical results are shown in the present paper for the first time. Since the theoretical relations are constructed using reduced variables, the calculations are made only on the case of C colliding on C.

  3. Treatment for Retinopathy of Prematurity in an Infant with Adenoviral Conjunctivitis

    Directory of Open Access Journals (Sweden)

    Murat Gunay

    2015-01-01

    Full Text Available Retinopathy of prematurity (ROP has been a major problematic disorder during childhood. Laser photocoagulation (LPC has been proven to be effective in most of the ROP cases. Adenoviral conjunctivitis (AVC is responsible for epidemics among adult and pediatric population. It has also been reported to be a cause of outbreaks in neonatal intensive care units (NICU several times. We herein demonstrate a case with AVC who underwent LPC for ROP. And we discuss the treatment methodology in such cases.

  4. Scattering anomaly in optics

    CERN Document Server

    Silveirinha, Mario G

    2016-01-01

    In time-reversal invariant electronic systems the scattering matrix is anti-symmetric. This property enables an effect, designated here as "scattering anomaly", such that the electron transport does not suffer from back reflections, independent of the specific geometry of the propagation path or the presence of time-reversal invariant defects. In contrast, for a generic time-reversal invariant photonic system the scattering matrix is symmetric and there is no similar anomaly. Here, it is theoretically proven that despite these fundamental differences there is a wide class of photonic platforms - in some cases formed only by time-reversal invariant media - in which the scattering anomaly can occur. It is shown that an optical system invariant under the action of the composition of the time-reversal, parity and duality operators is characterized by an anti-symmetric scattering matrix. Specific examples of photonic platforms wherein the scattering anomaly occurs are given, and it is demonstrated with full wave n...

  5. Scattering of Skyrmions

    Directory of Open Access Journals (Sweden)

    David Foster

    2015-08-01

    Full Text Available In this paper, we present a detailed study of Skyrmion–Skyrmion scattering for two B=1 Skyrmions in the attractive channel where we observe two different scattering regimes. For large separation, the scattering can be approximated as interacting dipoles. We give a qualitative estimate when this approximation breaks down. For small separations we observe an additional short-range repulsion which is qualitatively similar to monopole scattering. We also observe the interesting effect of “rotation without rotating” whereby two Skyrmions, whose orientations remain constant while well-separated, change their orientation after scattering. We can explain this effect by following preimages through the scattering process, thereby measuring which part of an in-coming Skyrmion forms part of an out-going Skyrmion. This leads to a new way of visualising Skyrmions. Furthermore, we consider spinning Skyrmions and find interesting trajectories.

  6. Introduction to neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    We give here an introduction to the theoretical principles of neutron scattering. The relationship between scattering- and correlation-functions is particularly emphasized. Within the framework of linear response theory (justified by the weakness of the basic interaction) the relation between fluctuation and dissipation is discussed. This general framework explains the particular power of neutron scattering as an experimental method. (author) 4 figs., 4 refs.

  7. Elastic scattering phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Mackintosh, R.S. [The Open University, School of Physical Sciences, Milton Keynes (United Kingdom)

    2017-04-15

    We argue that, in many situations, fits to elastic scattering data that were historically, and frequently still are, considered ''good'', are not justifiably so describable. Information about the dynamics of nucleon-nucleus and nucleus-nucleus scattering is lost when elastic scattering phenomenology is insufficiently ambitious. It is argued that in many situations, an alternative approach is appropriate for the phenomenology of nuclear elastic scattering of nucleons and other light nuclei. The approach affords an appropriate means of evaluating folding models, one that fully exploits available empirical data. It is particularly applicable for nucleons and other light ions. (orig.)

  8. Neutron scattering from fractals

    DEFF Research Database (Denmark)

    Kjems, Jørgen; Freltoft, T.; Richter, D.

    1986-01-01

    -angle neutron scattering studies of the variation with aggregation rate are presented. These results allow a very detailed comparison to be made with the theoretical scattering curves. Preliminary incoherent inelastic data on the low-frequency dynamics of hydroxylated silica particle aggregates show a clear...

  9. Incoherent Thomson scattering

    NARCIS (Netherlands)

    Donne, A. J. H.

    1996-01-01

    Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is

  10. Purely bianisotropic scatterers

    Science.gov (United States)

    Albooyeh, M.; Asadchy, V. S.; Alaee, R.; Hashemi, S. M.; Yazdi, M.; Mirmoosa, M. S.; Rockstuhl, C.; Simovski, C. R.; Tretyakov, S. A.

    2016-12-01

    The polarization response of molecules or meta-atoms to external electric and magnetic fields, which defines the electromagnetic properties of materials, can either be direct (electric field induces electric moment and magnetic field induces magnetic moment) or indirect (magnetoelectric coupling in bianisotropic scatterers). Earlier studies suggest that there is a fundamental bound on the indirect response of all passive scatterers: It is believed to be always weaker than the direct one. In this paper, we prove that there exist scatterers which overcome this bound substantially. Moreover, we show that the amplitudes of electric and magnetic polarizabilities can be negligibly small as compared to the magnetoelectric coupling coefficients. However, we prove that if at least one of the direct-excitation coefficients vanishes, magnetoelectric coupling effects in passive scatterers cannot exist. Our findings open a way to a new class of electromagnetic scatterers and composite materials.

  11. Efficacy and safety of intravitreal ranibizumab with panretinal photocoagulation followed by trabeculectomy compared with Ahmed glaucoma valve implantation in neovascular glaucoma.

    Science.gov (United States)

    Sun, Jin-Tao; Liang, Hai-Jing; An, Meng; Wang, Da-Bo

    2017-01-01

    To evaluate the efficacy and safety of intravitreal ranibizumab (IVR) with panretinal photocoagulation (PRP) followed by trabeculectomy compared with Ahmed glaucoma valve (AGV) implantation in neovascular glaucoma (NVG). This was a retrospective comparative study. We reviewed the cases of a total of 45 eyes from 45 NVG patients among which 23 eyes underwent AGV implantation and the other 22 underwent trabeculectomy. The causes of neovascular glaucoma included: diabetic retinopathy (25 eyes), and retinal vein occlusion (20 eyes). All patients received preoperative IVR combined with postoperative PRP. The mean best-corrected visual acuities (BCVA) were converted to the logarithms of the minimum angle of resolution (logMAR) for the statisitical analyses. Intraocular pressure (IOP), the logMAR BCVA and surgical complications were evaluated before and after surgery. The follow-up period was 12mo. A total of 39 cases showed complete regression of iris neovascularization at 7d after injection, and 6 cases showed a small amount of residual iris neovascularization. The success rates were 81.8% and 82.6% at 12mo after trabeculectomy and AGV implantation, respectively. In the trabeculectomy group, the logMAR BCVA improved at the last follow-up in 14 eyes, remained stable in 6 eyes and decreased in 2 eyes. In 4 cases, slight hyphemas developed after trabeculectomy. A shallow anterior chamber developed in 2 cases and 2 vitreous hemorrhages. In the AGV group, the logMAR BCVA improved in 14 eyes, remained stable in 5 eyes and decreased in 4 eyes. Slight hyphemas developed in 3 cases, and a shallow anterior chamber in 3 cases. The mean postoperative IOP was significantly lower in both groups after surgery (F=545.468, PAGV implantation+PRP and IVR+trabeculectomy+PRP in eyes with NVG.

  12. Manipulating scattering features by metamaterials

    Directory of Open Access Journals (Sweden)

    Lu Cui

    2016-01-01

    Full Text Available We present a review on manipulations of electromagnetic scattering features by using metamaterials or metasurfaces. Several approaches in controlling the scattered fields of objects are presented, including invisibility cloaks and radar illusions based on transformation optics, carpet cloak using gradient metamaterials, dc cloaks, mantle cloaks based on scattering cancellation, “skin” cloaks using phase compensation, scattering controls with coding/programmable metasurfaces, and scattering reductions by multilayered structures. Finally, the future development of metamaterials on scattering manipulation is predicted.

  13. Modelling Hyperboloid Sound Scattering

    DEFF Research Database (Denmark)

    Burry, Jane; Davis, Daniel; Peters, Brady

    2011-01-01

    The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...... both physical and digital models at three distinct scales. The results suggest hyperboloid geometry, while difficult to fabricate, facilitates sound scattering.......The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...

  14. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2016-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...

  15. Scattering from randomly oriented scatterers with strong permittivity fluctuations

    Science.gov (United States)

    Yueh, S. H.; Kong, J. A.; Shin, R. T.

    1990-01-01

    Strong permittivity fluctuation theory is used to solve the problem of scattering from a medium composed of completely randomly oriented scatterers under a low frequency limit. Gaussian statistics are not assumed for the renormalized scattering sources. Numerical results on effective permittivity are illustrated for oblate and prolate spheroidal scatterers and compared with the results for spherical scatterers. The results are consistent with discrete scatterer theory. The effective permittivity of a random medium embedded with nonspherical scatterers shows a higher imaginary part than the spherical scatterer case with equal correlation volume. Under the distorted Born approximation, the polarimetric covariance matrix for the backscattered electric field is calculated for half-space randomly oriented scatterers. The nonspherical geometry of the scatterers shows significant effects on the cross-polarized backscattering returns, and the correlation coefficient between HH and VV returns. The polarimetric backscattering coefficients can provide useful information in distinguishing the geometry of scatterers.

  16. Applied electromagnetic scattering theory

    CERN Document Server

    Osipov, Andrey A

    2017-01-01

    Besides classical applications (radar and stealth, antennas, microwave engineering), scattering and diffraction are enabling phenomena for some emerging research fields (artificial electromagnetic materials or metamaterials, terahertz technologies, electromagnetic aspects of nano-science). This book is a tutorial for advanced students who need to study diffraction theory. The textbook gives fundamental knowledge about scattering and diffraction of electromagnetic waves and provides some working examples of solutions for practical high-frequency scattering and diffraction problems. The book focuses on the most important diffraction effects and mechanisms influencing the scattering process and describes efficient and physically justified simulation methods - physical optics (PO) and the physical theory of diffraction (PTD) - applicable in typical remote sensing scenarios. The material is presented in a comprehensible and logical form, which relates the presented results to the basic principles of electromag...

  17. Gravitational Bhabha scattering

    Science.gov (United States)

    Santos, A. F.; Khanna, Faqir C.

    2017-10-01

    Gravitoelectromagnetism (GEM) as a theory for gravity has been developed similar to the electromagnetic field theory. A weak field approximation of Einstein theory of relativity is similar to GEM. This theory has been quantized. Traditional Bhabha scattering, electron-positron scattering, is based on quantized electrodynamics theory. Usually the amplitude is written in terms of one photon exchange process. With the development of quantized GEM theory, the scattering amplitude will have an additional component based on an exchange of one graviton at the lowest order of perturbation theory. An analysis will provide the relative importance of the two amplitudes for Bhabha scattering. This will allow an analysis of the relative importance of the two amplitudes as the energy of the exchanged particles increases.

  18. Impaired retinal autoregulation in small retinal arterioles before and after focal laser treatment for diabetic maculopathy.

    Science.gov (United States)

    Jeppesen, P; Bek, T

    2006-02-01

    To study the effect of an acute increase in the arterial blood pressure on the diameter response of retinal arterioles supplying areas with focal diabetic macular oedema before and after laser photocoagulation, and control arterioles supplying areas without oedema. In 17 diabetic patients the diameter response of arterioles after an increase in the arterial blood pressure induced by isometric exercise was studied using the retinal vessel analyser (RVA). In each patient a study arteriole supplying a focal area of macular oedema as well as a control arteriole supplying a retinal area without retinopathy lesions was selected, and the diameter response of these vessels was performed immediately before, and 1 hour and 3 months after focal laser photocoagulation of the focal oedema area. The diameter response was impaired in both study arterioles and control arterioles before focal laser photocoagulation. The treatment induced regression of the focal retinal oedema, but did not affect the diameter response in the arteriole supplying this area (p = 0.85). Impairment of the diameter response in small arterioles from diabetic patients does not parallel the regional distribution of retinopathy lesions. Other factors than disturbed autoregulation are probably involved in generating flow disturbances and oedema in diabetic maculopathy.

  19. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen

    1986-01-01

    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer excitati......Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...

  20. Inverse scattering theory: renormalization of the Lippmann-Schwinger equation for acoustic scattering in one dimension.

    Science.gov (United States)

    Kouri, Donald J; Vijay, Amrendra

    2003-04-01

    The most robust treatment of the inverse acoustic scattering problem is based on the reversion of the Born-Neumann series solution of the Lippmann-Schwinger equation. An important issue for this approach to inversion is the radius of convergence of the Born-Neumann series for Fredholm integral kernels, and especially for acoustic scattering for which the interaction depends on the square of the frequency. By contrast, it is well known that the Born-Neumann series for the Volterra integral equations in quantum scattering are absolutely convergent, independent of the strength of the coupling characterizing the interaction. The transformation of the Lippmann-Schwinger equation from a Fredholm to a Volterra structure by renormalization has been considered previously for quantum scattering calculations and electromagnetic scattering. In this paper, we employ the renormalization technique to obtain a Volterra equation framework for the inverse acoustic scattering series, proving that this series also converges absolutely in the entire complex plane of coupling constant and frequency values. The present results are for acoustic scattering in one dimension, but the method is general. The approach is illustrated by applications to two simple one-dimensional models for acoustic scattering.

  1. Clinical efficacy of intravitreal aflibercept versus panretinal photocoagulation for best corrected visual acuity in patients with proliferative diabetic retinopathy at 52 weeks (CLARITY): a multicentre, single-blinded, randomised, controlled, phase 2b, non-inferiority trial.

    Science.gov (United States)

    Sivaprasad, Sobha; Prevost, A Toby; Vasconcelos, Joana C; Riddell, Amy; Murphy, Caroline; Kelly, Joanna; Bainbridge, James; Tudor-Edwards, Rhiannon; Hopkins, David; Hykin, Philip

    2017-06-03

    Proliferative diabetic retinopathy is the most common cause of severe sight impairment in people with diabetes. Proliferative diabetic retinopathy has been managed by panretinal laser photocoagulation (PRP) for the past 40 years. We report the 1 year safety and efficacy of intravitreal aflibercept. In this phase 2b, single-blind, non-inferiority trial (CLARITY), adults (aged ≥18 years) with type 1 or 2 diabetes and previously untreated or post-laser treated active proliferative diabetic retinopathy were recruited from 22 UK ophthalmic centres. Patients were randomly assigned (1:1) to repeated intravitreal aflibercept (2 mg/0·05 mL at baseline, 4 weeks, and 8 weeks, and from week 12 patients were reviewed every 4 weeks and aflibercept injections were given as needed) or PRP standard care (single spot or mutlispot laser at baseline, fractionated fortnightly thereafter, and from week 12 patients were assessed every 8 weeks and treated with PRP as needed) for 52 weeks. Randomisation was by minimisation with a web-based computer generated system. Primary outcome assessors were masked optometrists. The treating ophthalmologists and participants were not masked. The primary outcome was defined as a change in best-corrected visual acuity at 52 weeks with a linear mixed-effect model that estimated adjusted treatment effects at both 12 weeks and 52 weeks, having excluded fluctuations in best corrected visual acuity owing to vitreous haemorrhage. This modified intention-to-treat analysis was reapplied to the per protocol participants. The non-inferiority margin was prespecified as -5 Early Treatment Diabetic Retinopathy Study letters. Safety was assessed in all participants. This trial is registered with ISRCTN registry, number 32207582. We recruited 232 participants (116 per group) between Aug 22, 2014 and Nov 30, 2015. 221 participants (112 in aflibercept group, 109 in PRP group) contributed to the modified intention-to-treat model, and 210 participants (104 in

  2. Segmented Liner to Control Mode Scattering

    Science.gov (United States)

    Gerhold, Carl H.; Jones, Michael G.; Brown, Martha C.

    2013-01-01

    The acoustic performance of duct liners can be improved by segmenting the treatment. In a segmented liner treatment, one stage of liner reduces the target sound and scatters energy into other acoustic modes, which are attenuated by a subsequent stage. The Curved Duct Test Rig is an experimental facility in which sound incident on the liner can be generated in a specific mode and the scatter of energy into other modes can be quantified. A series of experiments is performed in which the baseline configuration is asymmetric, that is, a liner is on one side wall of the test duct and the wall opposite is acoustically hard. Segmented liner treatment is achieved by progressively replacing sections of the hard wall opposite with liner in the axial direction, from 25% of the wall surface to 100%. It is found that the energy scatter from the (0,0) to the (0,1) mode reduces as the percentage of opposite wall treatment increases, and the frequency of peak attenuation shifts toward higher frequency. Similar results are found when the incident mode is of order (0,1) and scatter is into the (0,0) mode. The propagation code CDUCT-LaRC is used to predict the effect of liner segmenting on liner performance. The computational results show energy scatter and the effect of liner segmentation that agrees with the experimental results. The experiments and computations both show that segmenting the liner treatment is effective to control the scatter of incident mode energy into other modes. CDUCT-LaRC is shown to be a valuable tool to predict trends of liner performance with liner configuration.

  3. X-Ray-Scattering Measurements Of Strain In PEEK

    Science.gov (United States)

    Cebe, Peggy; Lowry, Lynn E.; Chung, Shirley Y.; Yavrouian, Andre H.; Gupta, Amitava

    1988-01-01

    Internal stress relieved by heating above glass-transition temperature. Report describes wide-angle x-ray scattering and differential scanning calorimetry of specimens of poly(etheretherketone) having undergone various thermal treatments. Wide-angle x-ray scattering particularly useful in determining distances between atoms, crystallinity, and related microstructurally generated phenomena, as thermal expansion and strain. Calorimetric measurements aid interpretation of scattering measurements by enabling correlation with thermal effects.

  4. Corticosteroid Treatment in Diabetic Macular Edema

    Directory of Open Access Journals (Sweden)

    Burcu Nurözler Tabakcı

    2017-06-01

    Full Text Available Diabetic macular edema is the most common cause of visual impairment in patients with diabetes mellitus. The pathogenesis of macular edema is complex and multifactorial. For many years, laser photocoagulation has been considered the standard therapy for the treatment of diabetic macular edema; however, few patients achieve significant improvements in visual acuity. Today the intravitreal administration of anti-inflammatory or anti-angiogenic agents together with the use of laser photocoagulation represents the standard of care for the treatment of this complication. The intravitreal route of administration minimizes the systemic side effects of corticosteroids. Steroid-related ocular side effects are elevated intraocular pressure and cataract, while injection-related complications include endophthalmitis, vitreous hemorrhage, and retinal detachment. In order to reduce the risks and complications, intravitreal implants have been developed recently to provide sustained release of corticosteroids and reduce repeated injections for the management of diabetic macular edema. In this review, the efficacy, safety, and therapeutic potential of intravitreal corticosteroids in diabetic macular edema are discussed with a review of recent literature.

  5. Efficacy and safety of intravitreal ranibizumab with panretinal photocoagulation followed by trabeculectomy compared with Ahmed glaucoma valve implantation in neovascular glaucoma

    Directory of Open Access Journals (Sweden)

    Jin-Tao Sun

    2017-03-01

    Full Text Available AIM: To evaluate the efficacy and safety of intravitreal ranibizumab (IVR with panretinal photocoagulation (PRP followed by trabeculectomy compared with Ahmed glaucoma valve (AGV implantation in neovascular glaucoma (NVG. METHODS: This was a retrospective comparative study. We reviewed the cases of a total of 45 eyes from 45 NVG patients among which 23 eyes underwent AGV implantation and the other 22 underwent trabeculectomy. The causes of neovascular glaucoma included: diabetic retinopathy (25 eyes, and retinal vein occlusion (20 eyes. All patients received preoperative IVR combined with postoperative PRP. The mean best-corrected visual acuities (BCVA were converted to the logarithms of the minimum angle of resolution (logMAR for the statisitical analyses. Intraocular pressure (IOP, the logMAR BCVA and surgical complications were evaluated before and after surgery. The follow-up period was 12mo. RESULTS: A total of 39 cases showed complete regression of iris neovascularization at 7d after injection, and 6 cases showed a small amount of residual iris neovascularization. The success rates were 81.8% and 82.6% at 12mo after trabeculectomy and AGV implantation, respectively. In the trabeculectomy group, the logMAR BCVA improved at the last follow-up in 14 eyes, remained stable in 6 eyes and decreased in 2 eyes. In 4 cases, slight hyphemas developed after trabeculectomy. A shallow anterior chamber developed in 2 cases and 2 vitreous hemorrhages. In the AGV group, the logMAR BCVA improved in 14 eyes, remained stable in 5 eyes and decreased in 4 eyes. Slight hyphemas developed in 3 cases, and a shallow anterior chamber in 3 cases. The mean postoperative IOP was significantly lower in both groups after surgery (F=545.468, P<0.05, and the mean postoperative logMAR BCVA was also significantly improved (F=10.964, P<0.05 with no significant difference between two groups. CONCLUSION: It is safe and effective to treat NVG with this combined procedure, and we

  6. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2017-01-01

    . In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus......We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  7. Electromagnetic scattering theory

    Science.gov (United States)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  8. Quantum Optical Multiple Scattering

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær

    . In the first part we use a scattering-matrix formalism combined with results from random-matrix theory to investigate the interference of quantum optical states on a multiple scattering medium. We investigate a single realization of a scattering medium thereby showing that it is possible to create entangled...... states by interference of squeezed beams. Mixing photon states on the single realization also shows that quantum interference naturally arises by interfering quantum states. We further investigate the ensemble averaged transmission properties of the quantized light and see that the induced quantum...... interference survives even after disorder averaging. The quantum interference manifests itself through increased photon correlations. Furthermore, the theoretical description of a measurement procedure is presented. In this work we relate the noise power spectrum of the total transmitted or reflected light...

  9. Λ scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Humberto [Instituto de Fisica - Universidade de São Paulo,Caixa Postal 66318, 05315-970 São Paulo, SP (Brazil); Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia)

    2016-06-17

    The CHY representation of scattering amplitudes is based on integrals over the moduli space of a punctured sphere. We replace the punctured sphere by a double-cover version. The resulting scattering equations depend on a parameter Λ controlling the opening of a branch cut. The new representation of scattering amplitudes possesses an enhanced redundancy which can be used to fix, modulo branches, the location of four punctures while promoting Λ to a variable. Via residue theorems we show how CHY formulas break up into sums of products of smaller (off-shell) ones times a propagator. This leads to a powerful way of evaluating CHY integrals of generic rational functions, which we call the Λ algorithm.

  10. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2016-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  11. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  12. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  13. Treatment of severe proliferative retinopathy and diabetic maculopathy.

    Science.gov (United States)

    Ooi, C G; Hardy, K J

    1999-01-01

    Strict blood glucose control, early detection and surveillance of diabetic retinopathy by means of validated screening programmes, and judicious use of laser photocoagulation can greatly reduce the risk of visual loss in diabetes. Some patients however, have aggressive neovascular disease resistant to laser treatment, or present at a late stage with advanced fibroproliferative disease, and may progress rapidly to blindness. In the elderly with Type 2 disease, diabetic maculopathy is more common and requires a different therapeutic approach. The present article describes two diabetic patients and discusses the management of patients with severe proliferative retinopathy or diabetic maculopathy. Copyright 1999 John Wiley & Sons, Ltd.

  14. Risk factors influencing the treatment outcome in diabetic macular oedema

    Directory of Open Access Journals (Sweden)

    Gupta Amod

    1996-01-01

    Full Text Available A multivariate analysis was done on 96 eyes to evaluate the effect of various risk factors on the final visual outcome after laser photocoagulation for clinically significant macular oedema (CSME in diabetic retinopathy. Advanced age of the patient, large size of CSME and poor baseline visual acuity were found to be significantly associated with poorer outcome (p<0.05. The association of nephropathy and hypertension with poorer visual outcome was of boderline significance (p = 0.054 and 0.07, respectively. Wavelength of the laser (argon or krypton used for treatment did not significantly influence the outcome.

  15. Optic disc pit maculopathy: the value of small-gauge vitrectomy, peeling, laser treatment, and gas tamponade.

    Science.gov (United States)

    Rizzo, Stanislao; Belting, Claudia; Genovesi-Ebert, Federica; Di Bartolo, Emanuele; Cresti, Federica; Cinelli, Laura; Allegrini, Luca

    2012-01-01

    To report the outcome of 10 patients with optic pit maculopathy (OPM) and evaluate the role of small-gauge vitrectomy, gas endotamponade, and additional laser photocoagulation treatment. We retrospectively investigated 10 patients who underwent small-gauge, sutureless vitrectomy for OPM, detachment of the posterior hyaloid, internal limiting membrane (ILM) peeling, endolaser photocoagulation on the temporal margin of the optic disc, and gas tamponade. Preoperative and postoperative best-corrected visual acuity (BCVA) was recorded and optical coherence tomography (OCT) imaging was performed. Seven out of 10 patients gained at least 2 lines of vision; 2 patients gained 1 line of vision. Visual improvement occurred more than 3 months after surgery. One myopic patient developed a macular hole postoperatively, resulting in a poor functional result even though complete retinal attachment was achieved. The functional outcome did not always correlate well with the OCT imaging, in which complete retinal reattachment was observed in 5 out of 10 eyes. The therapeutic approach should include both small-gauge vitrectomy and ILM peeling to relieve vitreoretinal traction, as well as laser photocoagulation of the temporal margin of the optic disc in order to prevent vitreous fluid from entering the subretinal/intraretinal space. In addition, the patients should be told that visual recovery can take a long time.

  16. Inversion assuming weak scattering

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus

    2013-01-01

    due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...

  17. Small Angle Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Volker S [ORNL

    2012-01-01

    Small Angle Neutron Scattering (SANS) probes structural details at the nanometer scale in a non-destructive way. This article gives an introduction to scientists who have no prior small-angle scattering knowledge, but who seek a technique that allows elucidating structural information in challenging situations that thwart approaches by other methods. SANS is applicable to a wide variety of materials including metals and alloys, ceramics, concrete, glasses, polymers, composites and biological materials. Isotope and magnetic interactions provide unique methods for labeling and contrast variation to highlight specific structural features of interest. In situ studies of a material s responses to temperature, pressure, shear, magnetic and electric fields, etc., are feasible as a result of the high penetrating power of neutrons. SANS provides statistical information on significant structural features averaged over the probed sample volume, and one can use SANS to quantify with high precision the structural details that are observed, for example, in electron microscopy. Neutron scattering is non-destructive; there is no need to cut specimens into thin sections, and neutrons penetrate deeply, providing information on the bulk material, free from surface effects. The basic principles of a SANS experiment are fairly simple, but the measurement, analysis and interpretation of small angle scattering data involves theoretical concepts that are unique to the technique and that are not widely known. This article includes a concise description of the basics, as well as practical know-how that is essential for a successful SANS experiment.

  18. Critical fluid light scattering

    Science.gov (United States)

    Gammon, Robert W.

    1988-01-01

    The objective is to measure the decay rates of critical density fluctuations in a simple fluid (xenon) very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such experiments were severely limited on Earth by the presence of gravity which causes large density gradients in the sample when the compressibility diverges approaching the critical point. The goal is to measure fluctuation decay rates at least two decades closer to the critical point than is possible on earth, with a resolution of 3 microK. This will require loading the sample to 0.1 percent of the critical density and taking data as close as 100 microK to the critical temperature. The minimum mission time of 100 hours will allow a complete range of temperature points to be covered, limited by the thermal response of the sample. Other technical problems have to be addressed such as multiple scattering and the effect of wetting layers. The experiment entails measurement of the scattering intensity fluctuation decay rate at two angles for each temperature and simultaneously recording the scattering intensities and sample turbidity (from the transmission). The analyzed intensity and turbidity data gives the correlation length at each temperature and locates the critical temperature. The fluctuation decay rate data from these measurements will provide a severe test of the generalized hydrodynamic theories of transport coefficients in the critical regions. When compared to equivalent data from binary liquid critical mixtures they will test the universality of critical dynamics.

  19. Inelastic magnon scattering

    Directory of Open Access Journals (Sweden)

    Robert de Mello Koch

    2017-05-01

    Full Text Available We study the worldsheet S-matrix of a string attached to a D-brane in AdS5×S5. The D-brane is either a giant graviton or a dual giant graviton. In the gauge theory, the operators we consider belong to the su(2|3 sector of the theory. Magnon excitations of open strings can exhibit both elastic (when magnons in the bulk of the string scatter and inelastic (when magnons at the endpoint of an open string participate scattering. Both of these S-matrices are determined (up to an overall phase by the su(2|22 global symmetry of the theory. In this note we study the S-matrix for inelastic scattering. We show that it exhibits poles corresponding to boundstates of bulk and boundary magnons. A crossing equation is derived for the overall phase. It reproduces the crossing equation for maximal giant gravitons, in the appropriate limit. Finally, scattering in the su(2 sector is computed to two loops. This two loop result, which determines the overall phase to two loops, will be useful when a unique solution to the crossing equation is to be selected.

  20. Inelastic magnon scattering

    Science.gov (United States)

    de Mello Koch, Robert; van Zyl, Hendrik J. R.

    2017-05-01

    We study the worldsheet S-matrix of a string attached to a D-brane in AdS5 ×S5. The D-brane is either a giant graviton or a dual giant graviton. In the gauge theory, the operators we consider belong to the su (2 | 3) sector of the theory. Magnon excitations of open strings can exhibit both elastic (when magnons in the bulk of the string scatter) and inelastic (when magnons at the endpoint of an open string participate) scattering. Both of these S-matrices are determined (up to an overall phase) by the su(2 | 2) 2 global symmetry of the theory. In this note we study the S-matrix for inelastic scattering. We show that it exhibits poles corresponding to boundstates of bulk and boundary magnons. A crossing equation is derived for the overall phase. It reproduces the crossing equation for maximal giant gravitons, in the appropriate limit. Finally, scattering in the su (2) sector is computed to two loops. This two loop result, which determines the overall phase to two loops, will be useful when a unique solution to the crossing equation is to be selected.

  1. Point sources and multipoles in inverse scattering theory

    CERN Document Server

    Potthast, Roland

    2001-01-01

    Over the last twenty years, the growing availability of computing power has had an enormous impact on the classical fields of direct and inverse scattering. The study of inverse scattering, in particular, has developed rapidly with the ability to perform computational simulations of scattering processes and led to remarkable advances in a range of applications, from medical imaging and radar to remote sensing and seismic exploration. Point Sources and Multipoles in Inverse Scattering Theory provides a survey of recent developments in inverse acoustic and electromagnetic scattering theory. Focusing on methods developed over the last six years by Colton, Kirsch, and the author, this treatment uses point sources combined with several far-reaching techniques to obtain qualitative reconstruction methods. The author addresses questions of uniqueness, stability, and reconstructions for both two-and three-dimensional problems.With interest in extracting information about an object through scattered waves at an all-ti...

  2. Polarimetric scattering and SAR information retrieval

    CERN Document Server

    Jin, Ya-Qiu

    2013-01-01

    Taking an innovative look at Synthetic Aperture Radar (SAR), this practical reference fully covers new developments in SAR and its various methodologies and enables readers to interpret SAR imagery An essential reference on polarimetric Synthetic Aperture Radar (SAR), this book uses scattering theory and radiative transfer theory as a basis for its treatment of topics. It is organized to include theoretical scattering models and SAR data analysis techniques, and presents cutting-edge research on theoretical modelling of terrain surface. The book includes quantitative app

  3. Small angle neutron scattering

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of

  4. Rayleigh's Scattering Revised

    Science.gov (United States)

    Kolomiets, Sergey; Gorelik, Andrey

    This report is devoted to a discussion of applicability limits of Rayleigh’s scattering model. Implicitly, Rayleigh’s ideas are being used in a wide range of remote sensing applications. To begin with it must be noted that most techniques which have been developed to date for measurements by means of active instruments for remote sensing in case of the target is a set of distributed moving scatters are only hopes, to say so, on measurements per se. The problem is that almost all of such techniques use a priori information about the microstructure of the object of interest during whole measurement session. As one can find in the literature, this approach may happily be applied to systems with identical particles. However, it is not the case with respect to scattering targets that consist of particles of different kind or having a particle size distribution. It must be especially noted that the microstructure of most of such targets changes significantly with time and/or space. Therefore, the true measurement techniques designed to be applicable in such conditions must be not only adaptable in order to take into account a variety of models of an echo interpretation, but also have a well-developed set of clear-cut criteria of applicability and exact means of accuracy estimation. So such techniques will require much more parameters to be measured. In spite of the fact that there is still room for some improvements within classical models and approaches, it is multiwavelength approach that may be seen as the most promising way of development towards obtaining an adequate set of the measured parameters required for true measurement techniques. At the same time, Rayleigh’s scattering is an invariant in regard to a change of the wavelength as it follows from the point of view dominating nowadays. In the light of such an idea, the synergy between multivawelength measurements may be achieved - to a certain extent - by means of the synchronous usage of Rayleigh’s and

  5. Light scattering reviews 8 radiative transfer and light scattering

    CERN Document Server

    Kokhanovsky, Alexander A

    2013-01-01

    Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.

  6. FDTD scattered field formulation for scatterers in stratified dispersive media.

    Science.gov (United States)

    Olkkonen, Juuso

    2010-03-01

    We introduce a simple scattered field (SF) technique that enables finite difference time domain (FDTD) modeling of light scattering from dispersive objects residing in stratified dispersive media. The introduced SF technique is verified against the total field scattered field (TFSF) technique. As an application example, we study surface plasmon polariton enhanced light transmission through a 100 nm wide slit in a silver film.

  7. Electromagnetic scattering from random media

    CERN Document Server

    Field, Timothy R

    2009-01-01

    - ;The book develops the dynamical theory of scattering from random media from first principles. Its key findings are to characterize the time evolution of the scattered field in terms of stochastic differential equations, and to illustrate this framework

  8. PERSISTENT SCATTERER INTERFEROMETRY USING SENTINEL-1 DATA

    Directory of Open Access Journals (Sweden)

    M. Crosetto

    2016-06-01

    Full Text Available This paper is focused on deformation monitoring using a Persistent Scatterer Interferometry technique and the interferometric SAR data acquired by the Sentinel-1 satellite of the European Space Agency. The first part of the paper describes the procedure used to process and analyze Sentinel-1 interferometric SAR data. Two main approaches are described. The first one is a simplified Persistent Scatterer Interferometry approach that exploits two key properties of the Sentinel-1 data: the high coherence of the 12-day interferograms and the reduced orbital tube. The second approach is a full Persistent Scatterer Interferometry approach, where a more sophisticate data treatment is employed. The second part of the paper illustrates the results obtained with the two processing approaches. Two case studies are described. The first one concerns landslide detection and monitoring. In this case, the simplified Persistent Scatterer Interferometry approach was used. The second one regards the deformation monitoring of an urban area. In this case, a full Persistent Scatterer Interferometry approach was used.

  9. Scattering of Rossby and Poincare waves off rough lateral boundaries

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A; Prahalad, Y; Sengupta, D.

    Unified treatment of wave scattering from a rough boundary, which was originally developed by Nakayama et al. is presented. The stationary nature of the boundary process is used to show that the wave field is also stationary, and therefore can...

  10. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)

    2014-11-04

    Nov 4, 2014 ... A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world's first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density ...

  11. Double parton scattering theory overview

    NARCIS (Netherlands)

    Diehl, Markus; Gaunt, Jonathan R.

    2017-01-01

    The dynamics of double hard scattering in proton-proton collisions is quite involved compared with the familiar case of single hard scattering. In this contribution, we review our theoretical understanding of double hard scattering and of its interplay with other reaction mechanisms.

  12. Seamount acoustic scattering

    Science.gov (United States)

    Boehlert, George W.

    The cover of the March 1 issue of Eos showed a time series of acoustic scattering above Southeast Hancock Seamount (29°48‧N, 178°05‧E) on July 17-18, 1984. In a comment on that cover Martin Hovland (Eos, August 2, p. 760) argued that gas or “other far reaching causes” may be involved in the observed acoustic signals. He favors a hypothesis that acoustic scattering observed above a seeping pockmark in the North Sea is a combination of bubbles, stable microbubbles, and pelagic organisms and infers that this may be a more general phenomenon and indeed plays a role in the attraction of organisms to seamounts

  13. Scattering problems in elastodynamics

    CERN Document Server

    Diatta, Andre; Wegener, Martin; Guenneau, Sebastien

    2016-01-01

    In electromagnetism, acoustics, and quantum mechanics, scattering problems can routinely be solved numerically by virtue of perfectly matched layers (PMLs) at simulation domain boundaries. Unfortunately, the same has not been possible for general elastodynamic wave problems in continuum mechanics. In this paper, we introduce a corresponding scattered-field formulation for the Navier equation. We derive PMLs based on complex-valued coordinate transformations leading to Cosserat elasticity-tensor distributions not obeying the minor symmetries. These layers are shown to work in two dimensions, for all polarizations, and all directions. By adaptative choice of the decay length, the deep subwavelength PMLs can be used all the way to the quasi-static regime. As demanding examples, we study the effectiveness of cylindrical elastodynamic cloaks of the Cosserat type and approximations thereof.

  14. Molecular-beam scattering

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  15. Means on scattered compacta

    Czech Academy of Sciences Publication Activity Database

    Banakh, T.; Bonnet, R.; Kubiś, Wieslaw

    2014-01-01

    Roč. 2, č. 1 (2014), s. 5-10 ISSN 2299-3231 R&D Projects: GA ČR(CZ) GAP201/12/0290 Institutional support: RVO:67985840 Keywords : scattered compact space * mean operation Subject RIV: BA - General Mathematics http://www.degruyter.com/view/j/taa.2014.2.issue-1/taa-2014-0002/taa-2014-0002. xml

  16. K sup + - scattering

    CERN Document Server

    Farhan, A M

    2002-01-01

    A prescription is given to construct an effective interaction that may describe the scattering of K sup + by spin-zero nuclei in a more reliable way. This prescription is based on the Lorentz invariant representation of the meson-nucleon amplitude and the use of the Klein-Gordon equation of motion. Good results for K sup + - sup 1 sup 2 C as well as K sup + - D total cross sections at various energies have been obtained. (author)

  17. Neutron scattering in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Knott, R.B. [Australian Nuclear Science and Technology Organisation, Menai (Australia)

    1994-12-31

    Neutron scattering techniques have been part of the Australian scientific research community for the past three decades. The High Flux Australian Reactor (HIFAR) is a multi-use facility of modest performance that provides the only neutron source in the country suitable for neutron scattering. The limitations of HIFAR have been recognized and recently a Government initiated inquiry sought to evaluate the future needs of a neutron source. In essence, the inquiry suggested that a delay of several years would enable a number of key issues to be resolved, and therefore a more appropriate decision made. In the meantime, use of the present source is being optimized, and where necessary research is being undertaken at major overseas neutron facilities either on a formal or informal basis. Australia has, at present, a formal agreement with the Rutherford Appleton Laboratory (UK) for access to the spallation source ISIS. Various aspects of neutron scattering have been implemented on HIFAR, including investigations of the structure of biological relevant molecules. One aspect of these investigations will be presented. Preliminary results from a study of the interaction of the immunosuppressant drug, cyclosporin-A, with reconstituted membranes suggest that the hydrophobic drug interdigitated with lipid chains.

  18. Plasma scattering of electromagnetic radiation

    CERN Document Server

    Sheffield, John

    1975-01-01

    Plasma Scattering of Electromagnetic Radiation covers the theory and experimental application of plasma scattering. The book discusses the basic properties of a plasma and of the interaction of radiation with a plasma; the relationship between the scattered power spectrum and the fluctuations in plasma density; and the incoherent scattering of low-temperature plasma. The text also describes the constraints and problems that arise in the application of scattering as a diagnostic technique; the characteristic performance of various dispersion elements, image dissectors, and detectors; and the ge

  19. Gravitational scattering of electromagnetic radiation

    Science.gov (United States)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  20. A comprehensive dosimetric study of pancreatic cancer treatment using three-dimensional conformal radiation therapy (3DCRT), intensity-modulated radiation therapy (IMRT), volumetric-modulated radiation therapy (VMAT), and passive-scattering and modulated-scanning proton therapy (PT)

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Xuanfeng; Dionisi, Francesco; Tang, Shikui; Ingram, Mark; Hung, Chun-Yu; Prionas, Evangelos; Lichtenwalner, Phil; Butterwick, Ian; Zhai, Huifang; Yin, Lingshu; Lin, Haibo; Kassaee, Alireza; Avery, Stephen, E-mail: stephen.avery@uphs.upenn.edu

    2014-07-01

    With traditional photon therapy to treat large postoperative pancreatic target volume, it often leads to poor tolerance of the therapy delivered and may contribute to interrupted treatment course. This study was performed to evaluate the potential advantage of using passive-scattering (PS) and modulated-scanning (MS) proton therapy (PT) to reduce normal tissue exposure in postoperative pancreatic cancer treatment. A total of 11 patients with postoperative pancreatic cancer who had been previously treated with PS PT in University of Pennsylvania Roberts Proton Therapy Center from 2010 to 2013 were identified. The clinical target volume (CTV) includes the pancreatic tumor bed as well as the adjacent high-risk nodal areas. Internal (iCTV) was generated from 4-dimensional (4D) computed tomography (CT), taking into account target motion from breathing cycle. Three-field and 4-field 3D conformal radiation therapy (3DCRT), 5-field intensity-modulated radiation therapy, 2-arc volumetric-modulated radiation therapy, and 2-field PS and MS PT were created on the patients’ average CT. All the plans delivered 50.4 Gy to the planning target volume (PTV). Overall, 98% of PTV was covered by 95% of the prescription dose and 99% of iCTV received 98% prescription dose. The results show that all the proton plans offer significant lower doses to the left kidney (mean and V{sub 18} {sub Gy}), stomach (mean and V{sub 20} {sub Gy}), and cord (maximum dose) compared with all the photon plans, except 3-field 3DCRT in cord maximum dose. In addition, MS PT also provides lower doses to the right kidney (mean and V{sub 18} {sub Gy}), liver (mean dose), total bowel (V{sub 20} {sub Gy} and mean dose), and small bowel (V{sub 15} {sub Gy} absolute volume ratio) compared with all the photon plans and PS PT. The dosimetric advantage of PT points to the possibility of treating tumor bed and comprehensive nodal areas while providing a more tolerable treatment course that could be used for dose

  1. Scattering Solar Thermal Concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Giebink, Noel C. [Pennsylvania State Univ., State College, PA (United States)

    2015-01-31

    This program set out to explore a scattering-based approach to concentrate sunlight with the aim of improving collector field reliability and of eliminating wind loading and gross mechanical movement through the use of a stationary collection optic. The approach is based on scattering sunlight from the focal point of a fixed collection optic into the confined modes of a sliding planar waveguide, where it is transported to stationary tubular heat transfer elements located at the edges. Optical design for the first stage of solar concentration, which entails focusing sunlight within a plane over a wide range of incidence angles (>120 degree full field of view) at fixed tilt, led to the development of a new, folded-path collection optic that dramatically out-performs the current state-of-the-art in scattering concentration. Rigorous optical simulation and experimental testing of this collection optic have validated its performance. In the course of this work, we also identified an opportunity for concentrating photovoltaics involving the use of high efficiency microcells made in collaboration with partners at the University of Illinois. This opportunity exploited the same collection optic design as used for the scattering solar thermal concentrator and was therefore pursued in parallel. This system was experimentally demonstrated to achieve >200x optical concentration with >70% optical efficiency over a full day by tracking with <1 cm of lateral movement at fixed latitude tilt. The entire scattering concentrator waveguide optical system has been simulated, tested, and assembled at small scale to verify ray tracing models. These models were subsequently used to predict the full system optical performance at larger, deployment scale ranging up to >1 meter aperture width. Simulations at an aperture widths less than approximately 0.5 m with geometric gains ~100x predict an overall optical efficiency in the range 60-70% for angles up to 50 degrees from normal. However, the

  2. Barrier distributions and scattering

    Energy Technology Data Exchange (ETDEWEB)

    Timmers, H.; Leigh, J.R.; Dasgupta, M.; Hinde, D.J.; Mein, J.C.; Morton, C.R.; Newton, J.O. [Department of Nuclear Physics, Australian National University, Canberra, ACT 0200 (Austria); Rowley, N. [Centre de Recherches Nucleaires, 23 Rue du Loess, F-67037 Strasbourg CEDEX 2 (France); Stefanini, A.M.; Ackermann, D.; Corradi, L.; He, J.H. [INFN, Laboratori Nazionali di Legnaro, Legnaro (PD) (Italy); Beghini, S.; Montagnoli, G.; Scarlassara, F.; Segato, G.F. [Universita di Padova and INFN Sezione di Padova, Padova (Italy)

    1997-10-01

    The extraction of representations of the fusion barrier distribution from backward-angle, quasi-elastic, elastic and transfer excitation functions is discussed. Such excitation functions have been measured for {sup 16}O, {sup 32}S and {sup 40}Ca projectiles incident on a variety of targets. The results are compared with representations obtained from fusion excitation functions. Varying in their sensitivity, all representations show evidence of the barrier structure. Differences between the scattering and the fusion representations can be related to the effects of coupling to residual, weak reaction channels. (author)

  3. Wave propagation scattering theory

    CERN Document Server

    Birman, M Sh

    1993-01-01

    The papers in this collection were written primarily by members of the St. Petersburg seminar in mathematical physics. The seminar, now run by O. A. Ladyzhenskaya, was initiated in 1947 by V. I. Smirnov, to whose memory this volume is dedicated. The papers in the collection are devoted mainly to wave propagation processes, scattering theory, integrability of nonlinear equations, and related problems of spectral theory of differential and integral operators. The book is of interest to mathematicians working in mathematical physics and differential equations, as well as to physicists studying va

  4. Raman scattering in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.F.

    1988-09-30

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  5. Scattering cross section of unequal length dipole arrays

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents a detailed and systematic analytical treatment of scattering by an arbitrary dipole array configuration with unequal-length dipoles, different inter-element spacing and load impedance. It provides a physical interpretation of the scattering phenomena within the phased array system. The antenna radar cross section (RCS) depends on the field scattered by the antenna towards the receiver. It has two components, viz. structural RCS and antenna mode RCS. The latter component dominates the former, especially if the antenna is mounted on a low observable platform. The reduction in the scattering due to the presence of antennas on the surface is one of the concerns towards stealth technology. In order to achieve this objective, a detailed and accurate analysis of antenna mode scattering is required. In practical phased array, one cannot ignore the finite dimensions of antenna elements, coupling effect and the role of feed network while estimating the antenna RCS. This book presents the RCS estimati...

  6. Efeito do tratamento térmico na microestrutura, turbostraticidade e superfície de carbono vítreo reticulado analisado por XPS, espalhamento Raman e voltametria cíclica Thermal treatment effect on the microstructure, turbostraticity, and surface of reticulated vitreous carbon analyzed by xps, Raman scattering, and cyclic voltammetry

    OpenAIRE

    Emerson Sarmento Gonçalves; Mirabel Cerqueira Rezende; Maurício Ribeiro Baldan; Neidenêi Gomes Ferreira

    2009-01-01

    The structural and surface properties of reticulated vitreous carbon (RVC) were discussed as a function of its heat treatment temperature (HTT), for samples produced in the range from 700 to 2000 ºC, using the furfuryl precursor resin. The samples were analyzed by x-ray photoelectron spectroscopy, first and second order Raman scattering as well as electrochemical response. Exploring the material turbostraticity concept, the interdependence between the RVC chemical surface variation and its de...

  7. Electron scattering and transport in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, G. J.; Cocks, D. G.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville 4810 (Australia); McEachran, R. P. [Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2015-04-21

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies.

  8. Electromagnetic Scattering and Material Characterization

    CERN Document Server

    Omar, Abbas

    2011-01-01

    Based on the author's more-than 30 years of experience, this first-of-its-kind volume presents a comprehensive and systematic analysis of electromagnetic fields and their scattering by material objects. The book considers all three categories of scattering environments commonly used for material measurements – unbounded regions, waveguides, and cavity resonators. The book covers such essential topics as electromagnetic field propagation, radiation, and scattering, containing mathematically rigorous approaches for the computation of electromagnetic fields and the explanation of their behavior.

  9. Development of general X-ray scattering model

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Joe, E-mail: jngray@iastate.edu; Wendt, Scott, E-mail: jngray@iastate.edu [Center for NDE, Iowa State University, Ames, IA 50011 (United States)

    2015-03-31

    X-ray scattering is a complex process made difficult to describe due to the effects of a complex energy spectrum interacting with a wide range of material types in complex geometry. The scattering is further complicated by the volume of material illuminated and the experimental configuration of the data acquisition. The importance of accounting for the key physics in scattering modeling is critical to the viability of the model. For example, scattering in the detector and the speed of the detector, as measured by the absorbed dose needed to produce a signal, are important in capturing undercut effects. Another example is the noise properties of the detectors are dependent on photon energy. We report on a semi-empirical treatment of x-ray scattering that includes a full energy treatment for a wide range of material types. We also include complex geometry effects that the part shape introduces. The treatment is based on experimental measurements using an energy dispersive germanium detector over energies from treatment is showing good results with experimental measurements of the scattering component agreeing with the model results to the 10% level over the range of x-ray energies and materials typical in industrial applications. Computation times for this model are in the 20 keV to 320 keV. Detector stripping routines for detector artifacts were developed. The computation time is in the range of a few minutes on a typical PC.

  10. Advances in total scattering analysis

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas E [Los Alamos National Laboratory; Kim, Hyunjeong [Los Alamos National Laboratory

    2008-01-01

    In recent years the analysis of the total scattering pattern has become an invaluable tool to study disordered crystalline and nanocrystalline materials. Traditional crystallographic structure determination is based on Bragg intensities and yields the long range average atomic structure. By including diffuse scattering into the analysis, the local and medium range atomic structure can be unravelled. Here we give an overview of recent experimental advances, using X-rays as well as neutron scattering as well as current trends in modelling of total scattering data.

  11. Light scattering by small particles

    CERN Document Server

    Hulst, H C van de

    1981-01-01

    ""A must for researchers using the techniques of light scattering."" ? S. C. Snowdon, Journal of the Franklin InstituteThe measurement of light scattering of independent, homogeneous particles has many useful applications in physical chemistry, meteorology and astronomy. There is, however, a sizeable gap between the abstract formulae related to electromagnetic-wave-scattering phenomena, and the computation of reliable figures and curves. Dr. van de Hulst's book enables researchers to bridge that gap. The product of twelve years of work, it is an exhaustive study of light-scattering properties

  12. Intravitreal ranibizumab as a primary or a combined treatment for severe retinopathy of prematurity

    Directory of Open Access Journals (Sweden)

    Arámbulo O

    2015-10-01

    Full Text Available Odalis Arámbulo,1 Gabriel Dib,1 Juan Iturralde,1 Fahir Duran,1 Miguel Brito,1 João B Fortes Filho2 1Department of Ophthalmology, University Hospital of Maracaibo, Maracaibo, Venezuela; 2Department of Ophthalmology, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil Purpose: The aim of the study was to assess the outcomes of severe retinopathy of prematurity (ROP in zone I or posterior zone II treated with intravitreal ranibizumab (IVR as monotherapy or combined treatment with laser photocoagulation.Methods: This is a retrospective study analyzing clinical records of the included patients. Patients were divided into two groups: group 1 included patients who received only IVR treatment; and group 2 was subdivided into group 2A – including patients with IVR as initial treatment and complementary laser photocoagulation if retinal neovascularization or plus disease did not regress, and group 2B – including patients with initial laser photocoagulation and IVR as rescue therapy. Favorable outcomes were regression of the retinal neovascularization and plus disease, meaning control of the disease. Unfavorable outcomes were progression to stages 4 and 5 of ROP.Results: Fifty-seven eyes were included in the study. Mean birth weight and gestational age were 1,281±254 g and 29.5±2.1 weeks, respectively. Group 1 comprised of 16 eyes, with favorable outcomes in 14 eyes (87.5%. Group 2 comprised of 41 eyes, with favorable outcomes in 29 eyes (70.7%, in a mean follow-up period of 12.8 months.Conclusion: IVR was effective to treat severe cases of ROP as a primary or a combined treatment. Forty-three of the 57 treated eyes (75.4% achieved regression of ROP and favorable outcomes. Keywords: aggressive posterior ROP, bevacizumab, prematurity, ranibizumab, retinopathy of prematurity, therapy, treatment, VEGF

  13. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  14. Elliptic scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, Carlos [Physics Division, National Center for Theoretical Sciences, National Tsing-Hua University,Hsinchu, Taiwan 30013 (China); Gomez, Humberto [Instituto de Fisica - Universidade de São Paulo,Caixa Postal 66318, 05315-970 São Paulo, SP (Brazil); Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia)

    2016-06-16

    Recently the CHY approach has been extended to one loop level using elliptic functions and modular forms over a Jacobian variety. Due to the difficulty in manipulating these kind of functions, we propose an alternative prescription that is totally algebraic. This new proposal is based on an elliptic algebraic curve embedded in a ℂP{sup 2} space. We show that for the simplest integrand, namely the n−gon, our proposal indeed reproduces the expected result. By using the recently formulated Λ−algorithm, we found a novel recurrence relation expansion in terms of tree level off-shell amplitudes. Our results connect nicely with recent results on the one-loop formulation of the scattering equations. In addition, this new proposal can be easily stretched out to hyperelliptic curves in order to compute higher genus.

  15. Scatter correction for cone-beam CT in radiation therapy.

    Science.gov (United States)

    Zhu, Lei; Xie, Yaoqin; Wang, Jing; Xing, Lei

    2009-06-01

    Cone-beam CT (CBCT) is being increasingly used in modern radiation therapy for patient setup and adaptive replanning. However, due to the large volume of x-ray illumination, scatter becomes a rather serious problem and is considered as one of the fundamental limitations of CBCT image quality. Many scatter correction algorithms have been proposed in literature, while a standard practical solution still remains elusive. In radiation therapy, the same patient is scanned repetitively during a course of treatment, a natural question to ask is whether one can obtain the scatter distribution on the first day of treatment and then use the data for scatter correction in the subsequent scans on different days. To realize this scatter removal scheme, two technical pieces must be in place: (i) A strategy to obtain the scatter distribution in on-board CBCT imaging and (ii) a method to spatially match a prior scatter distribution with the on-treatment CBCT projection data for scatter subtraction. In this work, simple solutions to the two problems are provided. A partially blocked CBCT is used to extract the scatter distribution. The x-ray beam blocker has a strip pattern, such that partial volume can still be accurately reconstructed and the whole-field scatter distribution can be estimated from the detected signals in the shadow regions using interpolation/extrapolation. In the subsequent scans, the patient transformation is determined using a rigid registration of the conventional CBCT and the prior partial CBCT. From the derived patient transformation, the measured scatter is then modified to adapt the new on-treatment patient geometry for scatter correction. The proposed method is evaluated using physical experiments on a clinical CBCT system. On the Catphan 600 phantom, the errors in Hounsfield unit (HU) in the selected regions of interest are reduced from about 350 to below 50 HU; on an anthropomorphic phantom, the error is reduced from 15.7% to 5.4%. The proposed method

  16. Treatment

    National Research Council Canada - National Science Library

    Safaa M. Raghab; Ahmed M. Abd El Meguid; Hala A. Hegazi

    2013-01-01

    ... composed. This paper presents the results of the analyses of leachate treatment from the solid waste landfill located in Borg El Arab landfill in Alexandria using an aerobic treatment process which was applied...

  17. Finite-element method for multigroup neutron transport: anisotropic scattering in 1-D slab geometry

    Energy Technology Data Exchange (ETDEWEB)

    Riyait, N.S.; Ackroyd, R.T.

    1987-01-01

    Proof-tests on 1-D multigroup neutron transport problems are reported for strong anisotropic scattering. These tests have been undertaken as part of the validation of the 3-D multigroup finite-element transport code FELTRAN for anisotropic scattering media. To illustrate the treatment of within-group and intergroup anisotropic scattering in the finite-element method the relevant theory is outlined. Ingroup scattering is checked using the backward-forward-isotropic (BFI) scattering law for source and eigenvalue problems. With this law anisotropic scattering problems can be transformed into equivalent isotropic scattering problems. In this way the well-validated isotropic scattering version of FELTRAN is used to validate the anisotropic version. Intergroup scattering effects are checked by solving few-group source problems for P/sub 1/ and P/sub 3/ scattering and the BFI scattering law. For P/sub 1/ and P/sub 3/ scattering checks are made with the discrete-ordinate finite-difference code ANISN and the spherical harmonics finite-difference code MARC/PN. For the BFI scattering law comparison is made with two-group exact solutions of Williams (1985) for 1-D systems.

  18. Thermal diffuse scattering in transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, B.D.; D' Alfonso, A.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Findlay, S.D. [School of Physics, Monash University, Victoria 3800 (Australia); Van Dyck, D. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); LeBeau, J.M. [North Carolina State University, Raleigh, NC 27695-7907 (United States); Stemmer, S. [Materials Department, University of California, Santa Barbara, CA 93106-5050 (United States); Allen, L.J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia)

    2011-12-15

    In conventional transmission electron microscopy, thermal scattering significantly affects the image contrast. It has been suggested that not accounting for this correctly is the main cause of the Stobbs factor, the ubiquitous, large contrast mismatch found between theory and experiment. In the case where a hard aperture is applied, we show that previous conclusions drawn from work using bright field scanning transmission electron microscopy and invoking the principle of reciprocity are reliable in the presence of thermal scattering. In the aperture-free case it has been suggested that even the most sophisticated mathematical models for thermal diffuse scattering lack in their numerical implementation, specifically that there may be issues in sampling, including that of the contrast transfer function of the objective lens. We show that these concerns can be satisfactorily overcome with modest computing resources; thermal scattering can be modelled accurately enough for the purpose of making quantitative comparison between simulation and experiment. Spatial incoherence of the source is also investigated. Neglect or inadequate handling of thermal scattering in simulation can have an appreciable effect on the predicted contrast and can be a significant contribution to the Stobbs factor problem. -- Highlights: Black-Right-Pointing-Pointer We determine the numerical requirements for accurate simulation of TDS in CTEM. Black-Right-Pointing-Pointer TDS can be simulated to high precision using the Born-Oppenheimer model. Black-Right-Pointing-Pointer Such calculations establish the contribution of TDS to the Stobbs factor problem. Black-Right-Pointing-Pointer Treating spatial incoherence using envelope functions increases image contrast. Black-Right-Pointing-Pointer Rigorous treatment of spatial incoherence significantly reduces image contrast.

  19. Juvenile diabetes eye complications and treatment

    Directory of Open Access Journals (Sweden)

    Dujić Mirjana P.

    2009-01-01

    Full Text Available Background/Aim. Diabetes mellitus (DM is a metabolic disorder characterized by hyperglycemia. The aim of this study was to explore the prognosis of patients with juvenile DM regarding diabetic eye complications, as well as the course of the diabetic eye disease related to the treatment undertaken. Methods. The study series involved 33 patients with juvenile DM during the period 1992-2007. The influence of the following factors on the course of the disease was estimated: age, the age of the disease onset, time when eye complications appeared, treatment modalities. Results. Of the total of 33 diabetics 15 patients were followed for 10 or more years and 18 from 5 to 9 years. At the time of their first visit the mean age was 23.12 ± 6.39 and the mean duration of DM was 17.42 ± 7.42 years. On their first visit, 7 eyes were without any complication. Most of the patients already developed clinical signs of proliferative diabetic retinopathy (41.39%, the signs of nonproliferative diabetic retinopathy (13.13% and macula involvement (10.10%. Diabetic cataract was found in 8.8% as well as tractional retinal detachment. Eleven out of 66 eyes were with vitreous hemorrhage. Two patients (5.5% suffered neovascular glaucoma. There was 1 (2.2% patient with developed rubeosis iridis and simplex glaucoma. Panretinal photocoagulation was performed in 65% of patients, focal photocoagulation in 15%, 12% patients underwent pars plana vitrectomy and 4% had cataract surgery with intraocular lens implantation and peripheral retinal kryopexy. Conclusion. Total vision loss due to eye complications of juvenile DM may be prevented if timely diagnosed with regular check ups and early treatment.

  20. Dynamic measurement of forward scattering

    DEFF Research Database (Denmark)

    Appel-Hansen, Jørgen; Rusch, W.

    1975-01-01

    A dynamic method for the measurement of forward scattering in a radio anechoic chamber is described. The quantity determined is the induced-field-ratio (IFR) of conducting cylinders. The determination of the IFR is highly sensitive to 1) multiple scattering between the cylinder and the obpring...

  1. Quantum scattering at low energies

    DEFF Research Database (Denmark)

    Derezinski, Jan; Skibsted, Erik

    2009-01-01

    For a class of negative slowly decaying potentials, including V(x):=−γ|x|−μ with 0quantum mechanical scattering theory in the low-energy regime. Using appropriate modifiers of the Isozaki–Kitada type we show that scattering theory is well behaved on the whole continuous spectrum...

  2. Quantum scattering at low energies

    DEFF Research Database (Denmark)

    Derezinski, Jan; Skibsted, Erik

    For a class of negative slowly decaying potentials, including with , we study the quantum mechanical scattering theory in the low-energy regime. Using modifiers of the Isozaki--Kitada type we show that scattering theory is well behaved on the {\\it whole} continuous spectrum of the Hamiltonian...

  3. Light scattering in ophthalmic research

    Science.gov (United States)

    Tuchin, Valery V.

    1994-06-01

    In the overview optical models of cornea, sclera, and crystalline lens humor will be presented. On the basis of these models eye tissue transmittance spectra and scattering indicatrices for the main informative elements of the mueller matrix will be analyzed. This paper will discuss some problems of eye tissue optical characteristics control, and possibilities and perspectives of elastic scattering spectroscopy in cataract diagnostics.

  4. Quantum scattering in one dimension

    Energy Technology Data Exchange (ETDEWEB)

    Barlette, Vania E. [Centro Universitario Franciscano, Santa Maria, RS (Brazil); Leite, Marcelo M. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil); Adhikari, Sadhan K. [Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, SP (Brazil)

    2000-09-01

    A self-contained discussion of non-relativistic quantum scattering is presented in the case of central potentials in one space dimension, which will facilitate the understanding of the more complex scattering theory in two and three dimensions. The present discussion illustrates in a simple way the concepts of partial-wave decomposition, phase shift, optical theorem and effective-range expansion. (author)

  5. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)

    2014-11-04

    Nov 4, 2014 ... determine the charge density distributions of short-lived exotic nuclei by elastic electron scattering. The first collision ... Electron scattering of highly unstable nuclei is not easy because it is difficult to produce ... both ends form a mirror potential to keep the ions longitudinally inside the SCRIT device, and the ...

  6. Light scattering by soap films

    NARCIS (Netherlands)

    Vrij, A.

    A theory is constructed describing the scattering from a liquid film (e.g., a soap film) of a light beam polarized normal to the plane of incidence. This scattering is due to the small irregular corrugations caused by thermal motion. The interference of the reflected incident beam with its multiple

  7. Surface scattering from ceramic phosphors

    Science.gov (United States)

    Lenef, Alan; Kelso, John; Peters, Christopher

    2012-02-01

    Scattering from phosphor converters and epitaxial surfaces is critical for solid state lighting device performance. Volume and surface scattering in solid state lighting devices can play a critical role in efficiency/efficacy, color points, and color angular consistency. Surface scattering in particular has not been well characterized in solid state lighting devices and can be complex to model. Because large angle scattering is important in lighting applications, surface scattering models generally require vector electromagnetic theory to avoid ambiguities often associated with scalar theory at these angles. Furthermore, surface features are often on the order of a few wavelengths, bringing ray tracing approaches into question. In this work, experimental angular scattering measurements are made on ceramic phosphor components where surface scattering dominates. The surface ceramic grain structure is responsible for the scattering. The results are compared to approximate statistical vector theory predictions that use the height autocorrelation functions as input. The autocorrelation measurements were derived from atomic-force microscopy topography measurements. Resulting predictions are in fairly good agreement with measurements.

  8. Prophylactic laser treatment in early age related maculopathy reduced the incidence of exudative complications

    Science.gov (United States)

    Frennesson, C; Nilsson, S

    1998-01-01

    AIM—To investigate the effect of prophylactic laser treatment on drusen area and incidence of exudative lesions in patients with soft drusen maculopathy.
METHODS—In a prospective study, patients with early age related maculopathy (ARM) and good visual acuity were randomised to laser treatment or to a control group. Each group consisted of two subgroups: a fellow eye group and a bilateral drusen group. At 3 years, 36 of 38 enrolled patients remained in the study. Photocoagulation was performed with an argon green laser, approximately 100 mild laser burns being placed on and between the drusen in a perifoveal temporal horseshoe-shaped area. Both cases and controls were subjected to fundus colour photographs and fluorescein angiograms at regular intervals, and the drusen area was calculated in both photographs and angiograms. At baseline, there were no significant differences (p>0.3-0.8) in drusen area between the groups.
RESULTS—In the treatment group, mean drusen area decreased significantly in the fundus photographs as well as in the angiograms (plaser treatment causes a reduction in drusen area in patients with soft drusen maculopathy and may lower the incidence of exudative lesions.

 Keywords: age related maculopathy; exudative complications; laser photocoagulation; soft drusen PMID:9924306

  9. Thomson scattering from a three-component plasma.

    Science.gov (United States)

    Johnson, W R; Nilsen, J

    2014-02-01

    A model for a three-component plasma consisting of two distinct ionic species and electrons is developed and applied to study x-ray Thomson scattering. Ions of a specific type are assumed to be identical and are treated in the average-atom approximation. Given the plasma temperature and density, the model predicts mass densities, effective ionic charges, and cell volumes for each ionic type, together with the plasma chemical potential and free-electron density. Additionally, the average-atom treatment of individual ions provides a quantum-mechanical description of bound and continuum electrons. The model is used to obtain parameters needed to determine the dynamic structure factors for x-ray Thomson scattering from a three-component plasma. The contribution from inelastic scattering by free electrons is evaluated in the random-phase approximation. The contribution from inelastic scattering by bound electrons is evaluated using the bound-state and scattering wave functions obtained from the average-atom calculations. Finally, the partial static structure factors for elastic scattering by ions are evaluated using a two-component version of the Ornstein-Zernike equations with hypernetted chain closure, in which electron-ion interactions are accounted for using screened ion-ion interaction potentials. The model is used to predict the x-ray Thomson scattering spectrum from a CH plasma and the resulting spectrum is compared with experimental results obtained by Feltcher et al. [Phys. Plasmas 20, 056316 (2013)].

  10. Heavy-ion nucleus scattering

    CERN Document Server

    Rahman, M A; Haque, S

    2003-01-01

    Heavy ion-nucleus scattering is an excellent laboratory to probe high spin phenomena, exotic nuclei and for the analysis of various exit channels. The Strong Absorption Model or the generalized diffraction models, which are semi-classical in nature, have been employed in the description of various heavy ion-nucleus scattering phenomena with reasonable success. But one needs to treat the deflection function (scattering angles) quantum mechanically in the Wave Mechanical picture for the appropriate description of the heavy-ion nucleus scattering phenomena. We have brought the mathematics for the cross-section of the heavy-ion nucleus scattering to an analytic expression taking account of the deflection function (scattering angles) quantum mechanically. sup 9 Be, sup 1 sup 6 O, sup 2 sup 0 Ne and sup 3 sup 2 S heavy-ion beams elastic scattering from sup 2 sup 8 Si, sup 2 sup 4 Mg and sup 4 sup 0 Ca target nuclei at various projectile energies over the range 20-151 MeV have been analysed in terms of the 2-paramet...

  11. Light scattering reviews 9 light scattering and radiative transfer

    CERN Document Server

    Kokhanovsky, Alexander A

    2014-01-01

    This book details modern methods of the radiative transfer theory. It presents recent advances in light scattering (measurements and theory) and highlights the newest developments in remote sensing of aerosol and cloud properties.

  12. Synthetic Fourier transform light scattering.

    Science.gov (United States)

    Lee, Kyeoreh; Kim, Hyeon-Don; Kim, Kyoohyun; Kim, Youngchan; Hillman, Timothy R; Min, Bumki; Park, Yongkeun

    2013-09-23

    We present synthetic Fourier transform light scattering, a method for measuring extended angle-resolved light scattering (ARLS) from individual microscopic samples. By measuring the light fields scattered from the sample plane and numerically synthesizing them in Fourier space, the angle range of the ARLS patterns is extended up to twice the numerical aperture of the imaging system with unprecedented sensitivity and precision. Extended ARLS patterns of individual microscopic polystyrene beads, healthy human red blood cells (RBCs), and Plasmodium falciparum-parasitized RBCs are presented.

  13. Vector boson scattering at CLIC

    Energy Technology Data Exchange (ETDEWEB)

    Kilian, Wolfgang; Fleper, Christian [Department Physik, Universitaet Siegen, 57068 Siegen (Germany); Reuter, Juergen [DESY Theory Group, 22603 Hamburg (Germany); Sekulla, Marco [Institut fuer Theoretische Physik, Karlsruher Institut fuer Technologie, 76131 Karlsruhe (Germany)

    2016-07-01

    Linear colliders operating in a range of multiple TeV are able to investigate the details of vector boson scattering and electroweak symmetry breaking. We calculate cross sections with the Monte Carlo generator WHIZARD for vector boson scattering processes at the future linear e{sup +} e{sup -} collider CLIC. By finding suitable cuts, the vector boson scattering signal processes are isolated from the background. Finally, we are able to determine exclusion sensitivities on the non-Standard Model parameters of the relevant dimension eight operators.

  14. A Discrete Scatterer Technique for Evaluating Electromagnetic Scattering from Trees

    Science.gov (United States)

    2016-09-01

    distribution is unlimited. 1 1. Introduction Developing sensing capabilities for the detection of ground targets concealed in a forest environment...scatterer simulation are 369 MB and 33 min/frequency, respectively, on a Dell Precision T7500 workstation with Intel Xeon CPU of 2.67 GHz, while those...2. Thirion L, Colin E, Dahon C. Capabilities of a forest coherent scattering model applied to radiometry, interferometry, and polarimetry at P

  15. Minimal Invasive Approach for Lips Venous Lake Treatment by 980 nm Diode Laser with Emphasis on the Aesthetic Results. А Clinical Series

    Directory of Open Access Journals (Sweden)

    Voynov Parvan P.

    2016-06-01

    Full Text Available Introduction: A venous lake (VL is a vascular lesion with common occurrence in many patients, manifested as a dark blue-to-violet compressible papule, caused by dilation of venules. The main reasons for the treatment of VL are aesthetic. The haemorrhaging episodes or impairment of oral normal functions are also under considerations. Treatment of lip VL includes surgical excision, selective photocoagulation, cryotherapy, sclerotherapy and electrodessication. The high-intensity diode laser is an option. The 980 nm diode laser is selectively absorbed by haemoglobin and selectively destroys blood vessels, minimising injury to the surrounding healthy skin.

  16. Rays, waves, and scattering topics in classical mathematical physics

    CERN Document Server

    Adam, John A

    2017-01-01

    This one-of-a-kind book presents many of the mathematical concepts, structures, and techniques used in the study of rays, waves, and scattering. Panoramic in scope, it includes discussions of how ocean waves are refracted around islands and underwater ridges, how seismic waves are refracted in the earth's interior, how atmospheric waves are scattered by mountains and ridges, how the scattering of light waves produces the blue sky, and meteorological phenomena such as rainbows and coronas. Rays, Waves, and Scattering is a valuable resource for practitioners, graduate students, and advanced undergraduates in applied mathematics, theoretical physics, and engineering. Bridging the gap between advanced treatments of the subject written for specialists and less mathematical books aimed at beginners, this unique mathematical compendium features problems and exercises throughout that are geared to various levels of sophistication, covering everything from Ptolemy's theorem to Airy integrals (as well as more technica...

  17. Exact results for chaotic scattering and experimental validation

    Science.gov (United States)

    Guhr, Thomas

    2017-12-01

    As scattering experiments are the key tool to obtain information on nuclei and other quantum systems, the foundations of scattering theory were laid already a long time ago. Compound nucleus scattering prompted the study of generic statistical features. In the Heidelberg approach, those are taken into account by assuming that the reaction zone is fully quantum chaotic. Later on, this approach turned out to be applicable to a large variety of systems on different scales, including classical wave systems. For a long time, the distribution of the off-diagonal scattering-matrix elements resisted analytical treatment. In two recent studies [1, 2], we fully solved this problem and we also carried out a comparison with data from microwave experiments. Some comment are made on our very recent results for the cross-section distributions.

  18. Laser light scattering basic principles and practice

    CERN Document Server

    Chu, Benjamin

    1994-01-01

    Geared toward upper-level undergraduate and graduate students, this text introduces the interdisciplinary area of laser light scattering, focusing chiefly on theoretical concepts of quasielastic laser scattering.

  19. Critical appraisal of ranibizumab in the treatment of diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Stewart MW

    2013-06-01

    Full Text Available Michael W StewartDepartment of Ophthalmology, Mayo School of Medicine, Jacksonville, FL, USAAbstract: Diabetic retinopathy is the leading cause of blindness among individuals of working age in industrialized nations, with most of the vision loss resulting from diabetic macular edema (DME. The formation of DME depends on the action of several growth factors and inflammatory mediators, but vascular endothelial growth factor (VEGF appears to be critical for breaking down the blood-retinal barrier and promoting the accumulation of macular edema. Laser photocoagulation has been the standard-of-care for three decades, and although it stabilizes vision, significant gains in visual acuity after treatment are unusual. Several VEGF inhibitors (pegaptanib, aflibercept, and ranibizumab have been initially developed and tested for the treatment of age-related macular degeneration and subsequently for DME. In Phase I, II, and III trials for DME, ranibizumab has been shown to be superior to macular laser photocoagulation and intraocular triamcinolone acetonide injections for improving visual acuity and drying the macula. As a result, ranibizumab is the only anti-VEGF drug that has been approved by the United States Food and Drug Administration for the treatment of DME. Most experts now consider intravitreal anti-VEGF therapy to be standard-of-care for DME involving the fovea.Keywords: aflibercept, bevacizumab, diabetic macular edema, diabetic retinopathy, ranibizumab, vascular endothelial growth factor

  20. Fiber 1.56-1.9 μm lasers in treatment of vascular malformations in children and adults

    Science.gov (United States)

    Abushkin, Ivan A.; Privalov, Valeriy A.; Lappa, Alexander V.; Minaev, Vladimir P.

    2013-03-01

    A few new low invasive fiber laser technologies for treatment of 1) capillary malformations (port-wine stains), 2) venous, arterial, and arteriovenous malformations, 3) lymphatic malformations of 3 types: micro, small and large-cystic lymphangiomas are presented in this work. There were applied 1.56 μm laser distant photocoagulation, 1.56 μm laser endovascular thermotherapy, 1.9 μm laser instant ablation, 1.9 μm laser interstitial thermotherapy, and 1.9 μm laser excision. The technologies were applied to about 300 patients. Good clinical and esthetic results have been achieved in great majority cases.

  1. The hydrogen anomaly problem in neutron Compton scattering

    Science.gov (United States)

    Karlsson, Erik B.

    2018-03-01

    Neutron Compton scattering (also called ‘deep inelastic scattering of neutrons’, DINS) is a method used to study momentum distributions of light atoms in solids and liquids. It has been employed extensively since the start-up of intense pulsed neutron sources about 25 years ago. The information lies primarily in the width and shape of the Compton profile and not in the absolute intensity of the Compton peaks. It was therefore not immediately recognized that the relative intensities of Compton peaks arising from scattering on different isotopes did not always agree with values expected from standard neutron cross-section tables. The discrepancies were particularly large for scattering on protons, a phenomenon that became known as ‘the hydrogen anomaly problem’. The present paper is a review of the discovery, experimental tests to prove or disprove the existence of the hydrogen anomaly and discussions concerning its origin. It covers a twenty-year-long history of experimentation, theoretical treatments and discussions. The problem is of fundamental interest, since it involves quantum phenomena on the subfemtosecond time scale, which are not visible in conventional thermal neutron scattering but are important in Compton scattering where neutrons have two orders of magnitude times higher energy. Different H-containing systems show different cross-section deficiencies and when the scattering processes are followed on the femtosecond time scale the cross-section losses disappear on different characteristic time scales for each H-environment. The last section of this review reproduces results from published papers based on quantum interference in scattering on identical particles (proton or deuteron pairs or clusters), which have given a quantitative theoretical explanation both regarding the H-cross-section reduction and its time dependence. Some new explanations are added and the concluding chapter summarizes the conditions for observing the specific quantum

  2. Scattering unitarity with effective dimension-6 operators

    Science.gov (United States)

    Ghosh, Swagata; Islam, Rashidul; Kundu, Anirban

    2018-01-01

    The effects of physics beyond the Standard Model (SM) may be parametrized by a set of higher-dimensional operators leading to an effective theory. The introduction of these operators makes the theory nonrenormalizable, and one may reasonably expect a violation of unitarity in 2\\to 2 scattering processes, depending on the values of the Wilson coefficients (WC) of the higher dimensional operators. Bounds on these coefficients may be obtained from demanding that there be no such unitarity violation below the scale of the effective theory. We show, at the lowest level, how the new operators affect the scattering amplitudes with longitudinal gauge bosons, scalars, and t\\overline{t} in the final state, and find that one may expect a violation of unitarity even at the LHC energies with small values of some of the new WC. For most of the others, such a violation needs large coefficients, indicating nonperturbative physics for the ultraviolet-complete theory, although a proper treatment necessitates the inclusion of even higher-dimensional operators. However, deviations from the SM expectations may be observed with even smaller values for these coefficients. We find that {WW}\\to {WW}, {WW}\\to {ZZ}, and {ZZ}\\to {hh} scatterings are the best possible channels to probe unitarity violations.

  3. Scattering of light by crystals

    CERN Document Server

    Hayes, William

    2012-01-01

    This authoritative graduate-level text describes inelastic light scattering by crystals and its use in the investigation of solid-state excitation, with experimental techniques common to all types of excitation. 1978 edition.

  4. Integration rules for scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Baadsgaard, Christian; Bjerrum-Bohr, N.E.J.; Bourjaily, Jacob L.; Damgaard, Poul H. [Niels Bohr International Academy and Discovery Center,Niels Bohr Institute, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark)

    2015-09-21

    As described by Cachazo, He and Yuan, scattering amplitudes in many quantum field theories can be represented as integrals that are fully localized on solutions to the so-called scattering equations. Because the number of solutions to the scattering equations grows quite rapidly, the contour of integration involves contributions from many isolated components. In this paper, we provide a simple, combinatorial rule that immediately provides the result of integration against the scattering equation constraints for any Möbius-invariant integrand involving only simple poles. These rules have a simple diagrammatic interpretation that makes the evaluation of any such integrand immediate. Finally, we explain how these rules are related to the computation of amplitudes in the field theory limit of string theory.

  5. Light Scattering in Solid IX

    CERN Document Server

    Cardona, Manuel

    2007-01-01

    This is the ninth volume of a well-established series in which expert practitioners discuss topical aspects of light scattering in solids. It reviews recent developments concerning mainly semiconductor nanostructures and inelastic x-ray scattering, including both coherent time-domain and spontaneous scattering studies. In the past few years, light scattering has become one of the most important research and characterization methods for studying carbon nanotubes and semiconducting quantum dots, and a crucial tool for exploring the coupled exciton--photon system in semiconductor cavities. Among the novel techniques discussed in this volume are pump--probe ultrafast measurements and those which use synchrotron radiation as light source. The book addresses improvements in the intensity, beam quality and time synchronization of modern synchrotron sources, which made it possible to measure the phonon dispersion in very small samples and to determine electronic energy bands as well as enabling real-time observations...

  6. Compton scattering at high intensities

    Energy Technology Data Exchange (ETDEWEB)

    Heinzl, Thomas, E-mail: thomas.heinzl@plymouth.ac.u [University of Plymouth, School of Mathematics and Statistics, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2009-12-01

    High-intensity Compton scattering takes place when an electron beam is brought into collision with a high power laser. We briefly review the main intensity signatures using the formalism of strong-field quantum electrodynamics.

  7. Neutron scattering and models: Titanium

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.

    1997-07-01

    Differential neutron elastic-scattering cross sections of elemental titanium were measured from 4.5 {r_arrow} 10.0 MeV in incident energy increments of {approx} 0.5 MeV. At each energy the measurements were made at forty or more scattering angles distributed between {approx} 17 and 160{degree}. Concurrently, differential neutron inelastic-scattering cross sections were measured for observed excitations of 0.975 {+-} 0.034, 1.497 {+-} 0.033, 2.322 {+-} 0.058, 3.252 {+-} 0.043, 3.700 {+-} 0.093, 4.317 {+-} 0.075 and 4.795 {+-} 0.100 MeV. All of the observed inelastically-scattered neutron groups were composites of contributions from several isotopes and/or levels. The experimental results were used to develop energy-average optical, statistical and coupled-channels models.

  8. Modeling fluctuations in scattered waves

    CERN Document Server

    Jakeman, E

    2006-01-01

    Fluctuations in scattered waves limit the performance of imaging and remote sensing systems that operate on all wavelengths of the electromagnetic spectrum. To better understand these fluctuations, Modeling Fluctuations in Scattered Waves provides a practical guide to the phenomenology, mathematics, and simulation of non-Gaussian noise models and discusses how they can be used to characterize the statistics of scattered waves.Through their discussion of mathematical models, the authors demonstrate the development of new sensing techniques as well as offer intelligent choices that can be made for system analysis. Using experimental results and numerical simulation, the book illustrates the properties and applications of these models. The first two chapters introduce statistical tools and the properties of Gaussian noise, including results on phase statistics. The following chapters describe Gaussian processes and the random walk model, address multiple scattering effects and propagation through an extended med...

  9. Parity nonconserving asymmetry in neutron-deuteron and proton-deuteron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kloet, W.M.; Gibson, B.F.; Stephenson, G.J. Jr.; Henley, E.M.

    1983-06-01

    Parity nonconservation in nucleon (N )-deuteron(d) scattering is examined at low energies (< or =40 MeV), particularly at 15 MeV. A Faddeev treatment is employed. For the strong N-N force a separable interaction, which fits scattering cross sections up to 60--100 MeV, is used; for the weak parity nonconserving NN force, an isoscalar short range term due to rho and ..omega.. exchanges and an isovector pion exchange contribution are included. Comparisons with parity nonconserving experimental asymmetries in NN scattering are made. For the parity nonconserving asymmetry in N-d scattering the contributions of various terms are separated, so that the model dependence of our results can be discussed. It is found that multiple scattering effects are important. The energy dependence of the parity nonconserving asymmetry in N-d scattering is found to differ qualitatively from that in NN scattering.

  10. Electromagnetic Scattering from Vegetation Canopies.

    Science.gov (United States)

    Sarabandi, Kamal

    Satellite-borne imaging radar has been proposed by the remote sensing community as a potential sensor for the acquisition of quantitative information about forested area on a global scale. To achieve this goal, it is necessary to develop retrieved algorithms that can provide reasonable estimate of vegetation biomass, leaf moisture content, and other physical parameters of tree canopies from multifrequency/multipolarization observations of their radar backscattering coefficients. Retrieval algorithms often are called "inverse problem" because their input/output parameters are the inverse of those associated with the direct problem, which in the present case refers to the development of a radar scattering model that relates the radar response to the canopy architecture and associated parameters. This thesis provides electromagnetic solutions to several problems associated with scattering from tree canopies. The forest canopy is modelled in the form of layers comprised of randomly distributed particles with known statistical properties. In Chapters 2-8 effective scattering models for different constituent particles of vegetation canopies are developed by employing appropriate asymptotic solutions and approximations. The effects of various physical features of the particles, such as curvature and variation in thickness for planar leaves and roughness for tree trunks, on their scattering behavior are examined. In Chapter 9 the scattering problem of inhomogeneous layered media is formulated via the vector radiative transfer equations and a first-order solution for the radar scattering coefficients is obtained. The radiative transfer solution is formulated in terms of two sets of input functions: the scattering matrices of the constituent particles, which are given in Chapters 2-8, and the size and orientation distribution functions of the particles. The radar scattering model and associated input functions can be used to conduct sensitivity analyses to determine the

  11. Radar interferometry persistent scatterer technique

    CERN Document Server

    Kampes, Bert M

    2014-01-01

    This volume is devoted to the Persistent Scatterer Technique, the latest development in radar interferometric data processing. It is the only book on Permanent Scatterer (PS) technique of radar interferometry, and it details a newly developed stochastic model and estimator algorithm to cope with possible problems for the application of the PS technique. The STUN (spatio-temporal unwrapping network) algorithm, developed to cope with these issues in a robust way, is presented and applied to two test sites.

  12. Isogeometric analysis of acoustic scattering

    OpenAIRE

    Venås, Jon Vegard

    2015-01-01

    Acoustic scattering has been thoroughly analyzed with the use of finite element analysis (FEA). The problem at hand is a coupled fluid-structure interaction problem on an unbounded domain, where an object of elastic material is surrounded by fluid. Using physical assumptions, the fluid is described by the wave equation which is transformed to the Helmholtz equation. That is, the frequency domain is considered instead of the time domain. In particular one is interested in the scattered pressur...

  13. Double parton scattering in CMS

    CERN Document Server

    Sunar Cerci, Deniz

    2017-01-01

    Recent results on the double parton scattering measurements performed using the proton-proton collision data collected with the CMS detector are presented. The observables, which are sensitive to double parton scattering, are investigated after being corrected for detector effects and selection efficiencies. Multivariate analysis techniques are used for increasing the sensitivity. The effective cross section, $\\sigma_{eff}$ is also extracted using different processes at various center-of-mass energies.

  14. Scattered light characterization of FORTIS

    Science.gov (United States)

    McCandliss, Stephan R.; Carter, Anna; Redwine, Keith; Teste, Stephane; Pelton, Russell; Hagopian, John; Kutyrev, Alexander; Li, Mary J.; Moseley, S. Harvey

    2017-08-01

    We describe our efforts to build a Wide-Field Lyman alpha Geocoronal simulator (WFLaGs) for characterizing the end-to-end sensitivity of FORTIS (Far-UV Off Rowland-circle Telescope for Imaging and Spectroscopy) to scattered Lyman α emission from outside of the nominal (1/2 degree)2 field-of-view. WFLaGs is a 50 mm diameter F/1 aluminum parabolic collimator fed by a hollow cathode discharge lamp with a 80 mm clear MgF2 window housed in a vacuum skin. It creates emission over a 10 degree FOV. WFLaGS will allow us to validate and refine a recently developed scattered light model and verify our scatter light mitigation strategies, which will incorporate low scatter baffle materials, and possibly 3-d printed light traps, covering exposed scatter centers. We present measurements of scattering intensity of Lyman alpha as a function of angle with respect to the specular reflectance direction for several candidate baffle materials. Initial testing of WFLaGs will be described.

  15. [Validation of a scatter correction method for IMRT verification using portal imaging].

    Science.gov (United States)

    Kyas, Ina; Partridge, Mike; Hesse, Bernd-Michael; Oelfke, Uwe; Schlegel, Wolfgang

    2004-01-01

    Complex dose-delivery techniques, as currently applied in intensity-modulated radiation therapy (IMRT), require a highly efficient treatment-verification process. The present paper deals with the problem of the scatter correction for therapy verification by use of portal images obtained by an electronic portal imaging device (EPID) based on amorphous silicon. It also presents an iterative method for the scatter correction of portal images based on Monte Carlo-generated scatter kernels. First applications of this iterative scatter-correction method for the verification of intensity-modulated treatments are discussed on the basis of MVCT- and dose reconstruction. Several experiments with homogeneous and anthropomorphic phantoms were performed in order to validate the scatter correction method and to investigate the precision and relevance in view of its clinical applicability. It is shown that the devised concept of scatter correction significantly improves the results of MVCT- and dose reconstruction models, which is in turn essential for an exact online IMRT verification.

  16. Fundamentals of neutron scattering by condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Scherm, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1996-12-31

    The purpose of this introductory lecture is to give the basic facts about the scattering of neutrons by condensed matter. This lecture is restricted to nuclear scattering, whereas magnetic scattering will be dealt with in an other course. Most of the formalism, however, can also be easily extended to magnetic scattering. (author) 17 figs., 3 tabs., 10 refs.

  17. Current approaches and perspectives in the medical treatment of diabetic retinopathy.

    Science.gov (United States)

    Porta, Massimo; Allione, Attilio

    2004-08-01

    Diabetic retinopathy is a leading cause of visual loss in industrialized countries. Its classification includes preclinical, nonproliferative (mild, moderate, and severe or preproliferative diabetic retinopathy) and proliferative stages (low risk, high risk, and advanced). Diabetic maculopathy (exudative, edematous, or ischemic) may be associated with either nonproliferative or proliferative retinopathy. Prevention requires the tightest possible control of both blood glucose and blood pressure. Laser photocoagulation remains the only procedure recommended for severe nonproliferative or proliferative retinopathy and maculopathy. Since it reduces legal blindness by more than 90% in proliferative retinopathy and prevents severe sight loss in diabetic maculopathy, photocoagulation is probably one of the most effective forms of treatment known today. Less destructive approaches are desirable, however, and those currently under phase 3 trial include blockade of angiotensin receptors, the beta-isoform of protein kinase C, and growth hormone secretion by long-acting analogues of somatostatin. Evidence from past randomized controlled studies does not support a role for inhibitors of platelet aggregation, aldose reductase, and advanced glycosylation end products in the prevention/treatment of retinopathy. Future approaches might include the use of thiamine and its analogues in the primary and secondary prevention of early retinopathy and blockers of vascular endothelial growth factor/vascular permeability factor in more advanced stages.

  18. Treatment of subretinal fluid associated with dome-shaped macula.

    Science.gov (United States)

    Chinskey, Nicholas D; Johnson, Mark W

    2013-11-01

    Dome-shaped macula is a recently described disorder seen in eyes with myopic posterior staphyloma. Vision loss may accompany sub-macular fluid accumulation, for which no effective treatment has been reported. The authors report the successful treatment of two female patients, aged 34 and 59 years, with chronic exudative macular detachment associated with dome-shaped macula. Symptoms of subretinal fluid had been present for at least 2 years in each case, and the fluid was refractory to multiple intravitreal bevacizumab injections in one eye. After a single session of half-fluence verteporfin photodynamic therapy, the submacular fluid resolved completely in each eye. In one eye, recurrent submacular fluid 2 years later responded partially to repeat photodynamic therapy and completely to focal laser photocoagulation. [Ophthalmic Surg Lasers Imaging Retina. 2013;44:593-595.]. Copyright 2013, SLACK Incorporated.

  19. High frequency and pulse scattering physical acoustics

    CERN Document Server

    Pierce, Allan D

    1992-01-01

    High Frequency and Pulse Scattering investigates high frequency and pulse scattering, with emphasis on the phenomenon of echoes from objects. Geometrical and catastrophe optics methods in scattering are discussed, along with the scattering of sound pulses and the ringing of target resonances. Caustics and associated diffraction catastrophes are also examined.Comprised of two chapters, this volume begins with a detailed account of geometrically based approximation methods in scattering theory, focusing on waves transmitted through fluid and elastic scatterers and glory scattering; surface ray r

  20. Treatment

    Directory of Open Access Journals (Sweden)

    Safaa M. Raghab

    2013-08-01

    The main goal of this study is to utilize a natural low cost material “as an accelerator additive to enhance the chemical treatment process using Alum coagulant and the accelerator substances were Perlite and Bentonite. The performance of the chemical treatment was enhanced using the accelerator substances with 90 mg/l Alum as a constant dose. Perlite gave better performance than the Bentonite effluent. The removal ratio for conductivity, turbidity, BOD and COD for Perlite was 86.7%, 87.4%, 89.9% and 92.8% respectively, and for Bentonite was 83.5%, 85.0%, 86.5% and 85.0% respectively at the same concentration of 40 mg/l for each.

  1. Thermal neutron scattering evaluation framework

    Science.gov (United States)

    Chapman, Chris; Leal, Luiz; Rahnema, Farzad; Danon, Yaron; Arbanas, Goran

    2017-09-01

    A neutron scattering kernel data evaluation framework for computation of model-dependent predictions and their uncertainties is outlined. In this framework, model parameters are fitted to double-differential cross section measurements and their uncertainties. For convenience, the initial implementation of this framework uses the molecular dynamics model implemented in the GROMACS code. It is applied to light water using the TIP4P/2005f interaction model. These trajectories computed by GROMACS are then processed using nMOLDYN to compute the density of states, which is then used to calculate the scattering kernel using the Gaussian approximation. Double differential cross sections computed from the scattering kernel are then fitted to double-differential scattering data measured at the Spallation Neutron Source detector at Oak Ridge National Laboratory. The fitting procedure is designed to yield optimized model-parameters and their uncertainties in the form of a covariance matrix, from which new evaluations of thermal neutron scattering kernel will be generated. The Unified Monte Carlo method will be used to fit the simulation data to the experimental data.

  2. Luminosity calibration from elastic scattering

    CERN Document Server

    Stenzel, H

    2006-01-01

    The absolute luminosity of the LHC at the ATLAS interaction point will be calibrated by the measurement of the t-distribution of elastic pp-scattering in the Coulomb-Nuclear interference region. The ALFA detector housed in Roman Pots located 240m away from IP1 is designed to approach the beam at mm distance and to measure elastic pp-scattering at micro-radian scattering angles. This measurement will be performed with dedicated runs using a special beam optics with high beta* and parallel-to-point focusing in order to access the Coulomb regime. In this note the expected performance of this method, evaluated with a simulation of the experimental set-up, is presented.

  3. Quantifying entanglement with scattering experiments

    Science.gov (United States)

    Marty, O.; Epping, M.; Kampermann, H.; Bruß, D.; Plenio, M. B.; Cramer, M.

    2014-03-01

    We show how the entanglement contained in states of spins arranged on a lattice may be lower bounded with observables arising in scattering experiments. We focus on the partial differential cross section obtained in neutron scattering from magnetic materials but our results are sufficiently general such that they may also be applied to, e.g., optical Bragg scattering from ultracold atoms in optical lattices or from ion chains. We discuss resonating valence bond states and ground and thermal states of experimentally relevant models—such as the Heisenberg, Majumdar-Ghosh, and XY models—in different geometries and with different spin numbers. As a by-product, we find that for the one-dimensional XY model in a transverse field such measurements reveal factorization and the quantum phase transition at zero temperature.

  4. Helium atom scattering from surfaces

    CERN Document Server

    1992-01-01

    High resolution helium atom scattering can be applied to study a number of interesting properties of solid surfaces with great sensitivity and accuracy. This book treats in detail experimental and theoretical aspects ofthis method as well as all current applications in surface science. The individual chapters - all written by experts in the field - are devoted to the investigation of surface structure, defect shapes and concentrations, the interaction potential, collective and localized surface vibrations at low energies, phase transitions and surface diffusion. Over the past decade helium atom scattering has gained widespread recognitionwithin the surface science community. Points in its favour are comprehensiveunderstanding of the scattering theory and the availability of well-tested approximation to the rigorous theory. This book will be invaluable to surface scientists wishing to make an informed judgement on the actual and potential capabilities of this technique and its results.

  5. SCATTERING FROM RAMIFIED POLYMERIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    M.Benhamou

    2004-01-01

    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  6. Scattering functions of Platonic solids

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xin [Rensselaer Polytechnic Institute; Shew, Chwen-Yang [City University of New York (CUNY); He, Lilin [ORNL; Meilleur, Flora [ORNL; Myles, Dean A A [ORNL; Liu, Emily [Rensselaer Polytechnic Institute; Zhang, Yang [ORNL; Smith, Greg [ORNL; Herwig, Kenneth W [ORNL; Pynn, Roger [ORNL; Chen, Wei-Ren [ORNL

    2011-01-01

    The single-particle small-angle scattering properties of five Platonic solids, including the tetrahedron, hexahedron, octahedron, dodecahedron and icosahedron, are systematically investigated. For each given geometry, the Debye spatial autocorrelation function, pair distance distribution function and intraparticle structure factor (form factor) are calculated and compared with the corresponding scattering function of a spherical reference system. From the theoretical models, the empirical relationship between the dodecahedral and icosahedral structural characteristics and those of the equivalent spheres is found. Moreover, the single-particle scattering properties of icosahedral and spherical shells with identical volume are investigated, and the prospect of using different data analysis approaches to explore their structural differences is presented and discussed.

  7. Scattering functions of Platonic solids

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ren [ORNL; Herwig, Kenneth W [ORNL; Li, Xin [ORNL; Liu, Emily [Rensselaer Polytechnic Institute (RPI); Pynn, Roger [ORNL; Shew, Chwen-Yang [City University of New York (CUNY); Smith, Gregory Scott [ORNL; Myles, Dean A A [ORNL; He, Lilin [ORNL; Meilleur, Flora [ORNL

    2011-01-01

    In this report the single-particle scattering properties of five Platonic solids, including tetrahedron, hexahedron, octahedron, dodecahedron and icosahedron, are investigated in a systematic manner. For each given geometry, the Debye spatial autocorrelation function (r), pair distance distribution function (PDDF) p (r) and intraparticle structure factor (form factor) P (Q) are respectively calculated and compared to the corresponding scattering function of the spherical referential system. Based on our theoretical models, the empirical relationship between the dodecahedral and icosahedral structural characteristics and those of the equivalent spheres is found. Moreover, the single-particle scattering properties of the icosahedral and the spherical shells with the same volume are further investigated and the prospect of using different data analysis approaches to explore their structural difference is also presented and discussed.

  8. Optical Waveguide Scattering Reduction. II.

    Science.gov (United States)

    1980-12-01

    straightforward (23)application of Fraunhofer diffraction theory: ik(z 4-a/2) . 1/2 A(y,z) = A oe 0 2ik an [ix(z-z 0)Io , 0 0 a/2 eikr f e iky ’ ,dy. (45) -a12 The...scattering analysis in the Rayleigh-Debye limit. 45 17 Definition of parameters for determining the scattered field in the Fraunhofer zone...They present photo- graphs showing lO-pm sized triangular and hexagonal inclusions which they describe as metal particles from the crucible. We have not

  9. Optical scattering measurement and analysis

    CERN Document Server

    Stover, John C

    2012-01-01

    Newly included are scatter models for pits and particles as well as the use of wafer scanners to locate and size isolated surface features. New sections cover the multimillion-dollar wafer scanner business, establishing that microroughness is the noise, not the signal, in these systems. Scatter measurements, now routinely used to determine whether small-surface features are pits or particles and inspiring new technology that provides information on particle material, are also discussed. These new capabilities are now supported by a series of international standards, and a new chapter reviews t

  10. Optical properties of two-dimensional magnetoelectric point scattering lattices

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Sersic, Ivana; Koenderink, A. Femius

    2013-01-01

    We explore the electrodynamic coupling between a plane wave and an infinite two-dimensional periodic lattice of magnetoelectric point scatterers, deriving a semianalytical theory with consistent treatment of radiation damping, retardation, and energy conservation. We apply the theory to arrays of...

  11. Minimal Invasive Approach for Lips Venous Lake Treatment by 980 nm Diode Laser with Emphasis on the Aesthetic Results. А Clinical Series.

    Science.gov (United States)

    Voynov, Parvan P; Tomov, Georgi T; Mateva, Nonka G

    2016-01-01

    A venous lake (VL) is a vascular lesion with common occurrence in many patients, manifested as a dark blue-to-violet compressible papule, caused by dilation of venules. The main reasons for the treatment of VL are aesthetic. The haemorrhaging episodes or impairment of oral normal functions are also under considerations. Treatment of lip VL includes surgical excision, selective photocoagulation, cryotherapy, sclerotherapy and electrodessication. The high-intensity diode laser is an option. The 980 nm diode laser is selectively absorbed by haemoglobin and selectively destroys blood vessels, minimising injury to the surrounding healthy skin. The purpose of this study was to evaluate the effectiveness of diode laser in the treatment of VL lesions with the accent on the postoperative defects and aesthetic results. 35 patients aged 37 to 71 were included in this study. A 980 nm diode laser was used in noncontact mode, under local anaesthesia in continuous wave (2-3W, for 20-60s). All patients received only one procedure. Healing process was completed within 2 to 4 weeks after treatment with no scarring. None of the typical adverse effects were observed in the process of healing. Selective photocoagulation is an effective method for treatment of VL. Lower morbidity, minimal patient discomfort and satisfactory functional and aesthetic results are favourable for patients. To optimise the results and to reduce the adverse effects, basic knowledge on lasers and laser-tissue interactions is requisite.

  12. Optical scattering in glass ceramics

    NARCIS (Netherlands)

    Mattarelli, M.; Montagna, M.; Verrocchio, P.

    2008-01-01

    The transparency of glass ceramics with nanocrystals is generally higher than that expected from the theory of Rayleigh scattering. We attribute this ultra-transparency to the spatial correlation of the nanoparticles. The structure factor is calculated for a simple model system, the random

  13. Nuclear matter and electron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sick, I. [Dept. fuer Physik und Astronomie, Univ. Basel (Switzerland)

    1998-06-01

    We show that inclusive electron scattering at large momentum transfer allows a measurement of short-range properties of nuclear matter. This provides a very valuable constraint in selecting the calculations appropriate for predicting nuclear matter properties at the densities of astrophysical interest. (orig.)

  14. Antiproton-Proton Glory Scattering

    CERN Multimedia

    2002-01-01

    This experiment measures @*p and K|-p backwards scattering between 8 and 16 GeV/c in the Omega spectrometer using the S1 beam, with sensitivities of several events per nanobarn. The mechanism responsible for backward scattering in channels not mediated by particle exchange is not understood, and could be almost energy-independent glory scattering, especially since relatively high cross sections of 190~(@*p) and 120~(K|-p)nb have been measured earlier at 5~GeV/c. @p|-p backwards scattering is measured for monitoring purposes. The trigger requires a forward particle of momentum close to the beam momentum. Absence of light in the two forward Cerenkov counters indicates that the particle is a proton. Combinations of an incident @p|- and an outgoing K|+, or an incident K|- or @* and an outgoing @p|+, cover the following byproducts: @*p~@A~@p|+@p|- which is an (allowed) baryon exchange reaction, and the exotic exchange reactions @p|-p~@A~K|+Y K|-p~@A~@p|+Y|-, where Y|- may be the @S|- or the Y*|-(1385).

  15. Coupling between minimum scattering antennas

    DEFF Research Database (Denmark)

    Andersen, J.; Lessow, H; Schjær-Jacobsen, Hans

    1974-01-01

    Coupling between minimum scattering antennas (MSA's) is investigated by the coupling theory developed by Wasylkiwskyj and Kahn. Only rotationally symmetric power patterns are considered, and graphs of relative mutual impedance are presented as a function of distance and pattern parameters. Crossed......-dipoles and helices are considered in order to establish a correspondence with simple antenna structures....

  16. Pentagon diagrams of Bhabha scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, J. [Bielefeld Univ. (Germany). Fakultaet fuer Physik]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Riemann, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Gluza, J.; Kajda, K. [Uniwersytet Slaski, Katowice (Poland). Inst. Fizyki

    2007-12-15

    We report on tensor reduction of five point integrals needed for the evaluation of loop-by-loop corrections to Bhabha scattering. As an example we demonstrate the calculation of the rank two tensor integral with cancellation of the spurious Gram determinant in the denominator. The reduction scheme is worked out for arbitrary five point processes. (orig.)

  17. ENZYME CATALYTIC RESONANCE SCATTERING SPECTRAL ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. Hydrogen peroxide oxidized guaiacol to form tetramer particles that exhibited a strong resonance scattering (RS) peak at 530 nm in the presence of horseradish peroxidase (HRP) in citric acid-Na2HPO4 buffer solution of pH 4.4. The RS peak increased when the concentration of hydrogen peroxide increased.

  18. Thermally stimulated scattering in plasmas

    DEFF Research Database (Denmark)

    Dysthe, K. B.; Mjølhus, E.; Pécseli, H. L.

    1985-01-01

    A theory for stimulated scattering of a laser beam is formulated where the dominant nonlinearity is the ohmic heating of the plasma. The analysis is carried out with particular reference to experimental investigations of CO2 laser heating of linear discharge plasma. In the conditions characterizing...

  19. Simple model for molecular scattering

    Science.gov (United States)

    Mehta, Nirav; Ticknor, Christopher; Hazzard, Kaden

    2017-04-01

    The collisions of ultracold molecules are qualitatively different from the collisions of ultracold atoms due to the high density of bimolecular resonances near the collision energy. We present results from a simple N-channel scattering model with square-well channel potentials and constant channel couplings (inside the well) designed to reproduce essential features of chaotic molecular scattering. The potential depths and channel splittings are tuned to reproduce the appropriate density of states for the short-range bimolecular collision complex (BCC), which affords a direct comparison of the resulting level-spacing distribution to that expected from random matrix theory (RMT), namely the so-called Wigner surmise. The density of states also sets the scale for the rate of dissociation from the BCC to free molecules, as approximated by transition state theory (TST). Our model affords a semi-analytic solution for the scattering amplitude in the open channel, and a determinantal equation for the eigenenergies of the short-ranged BCC. It is likely the simplest finite-ranged scattering model that can be compared to expectations from the approximations of RMT, and TST. The validity of these approximations has implications for the many-channel Hubbard model recently developed. This research was funded in part by the National Science Foundation under Grant No. NSF PHY-1125915.

  20. Sizing of Microparticles from Angular Scattering Ratio

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Karamehmedovic, Mirza

    This technical note deals with light scattering measurements for sizing of micrometer-scale particles in a suspension.......This technical note deals with light scattering measurements for sizing of micrometer-scale particles in a suspension....

  1. Time-Reversal Analysis for Scatterer Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D H; Berryman, J G

    2003-11-05

    Only the simplest monopole scattering behavior has usually been treated in previous time-reversal analyses. A new application of time-reversal processing of wave scattering data permits characterization of scatterers by analyzing the number and nature of the singular functions (or eigenfunctions) associated with individual scatterers when they have multiple contributions from monopole, dipole and/or quadrupole scattering terms. We discuss acoustic, elastic, and electromagnetic scattering problems for low frequencies (ka < 1, k being the wavenumber and a the radius of the scatterer). Specific examples for electromagnetic scattering from one of a number of small conducting spheres show that each sphere can have up to six distinct time-reversal eigenfunctions associated with it.

  2. Adenovirus Particle Quantification in Cell Lysates Using Light Scattering.

    Science.gov (United States)

    Hohl, Adrian; Ramms, Anne Sophie; Dohmen, Christian; Mantwill, Klaus; Bielmeier, Andrea; Kolk, Andreas; Ruppert, Andreas; Nawroth, Roman; Holm, Per Sonne

    2017-10-01

    Adenoviral vector production for therapeutic applications is a well-established routine process. However, current methods for measurement of adenovirus particle titers as a quality characteristic require highly purified virus preparations. While purified virus is typically obtained in the last step of downstream purification, rapid and reliable methods for adenovirus particle quantification in intermediate products and crude lysates to allow for optimization and validation of cell cultures and intermediate downstream processing steps are currently not at hand. Light scattering is an established process to measure virus particles' size, though due to cell impurities, adequate quantification of adenovirus particles in cell lysates by light scattering has been impossible until today. This report describes a new method using light scattering to measure virus concentration in nonpurified cell lysates. Here we report application of light scattering, a routine method to measure virus particle size, to virus quantification in enzymatically conditioned crude lysates. Samples are incubated with phospholipase A2 and benzonase and filtered through a 0.22 μm filter cartridge prior to quantification by light scattering. Our results show that this treatment provides a precise method for fast and easy determination of total adenovirus particle numbers in cell lysates and is useful to monitor virus recovery throughout all downstream processing.

  3. Scattering of light and other electromagnetic radiation

    CERN Document Server

    Kerker, Milton

    1969-01-01

    The Scattering of Light and Other Electromagnetic Radiation discusses the theory of electromagnetic scattering and describes some practical applications. The book reviews electromagnetic waves, optics, the interrelationships of main physical quantities and the physical concepts of optics, including Maxwell's equations, polarization, geometrical optics, interference, and diffraction. The text explains the Rayleigh2 theory of scattering by small dielectric spheres, the Bessel functions, and the Legendre functions. The author also explains how the scattering functions for a homogenous sphere chan

  4. Spatial photon correlations in multiple scattering media

    DEFF Research Database (Denmark)

    Smolka, Stephan; Muskens, O.; Lagendijk, A.

    2010-01-01

    We present the first angle-resolved measurements of spatial photon correlations that are induced by multiple scattering of light. The correlation relates multiple scattered photons at different spatial positions and depends on incident photon fluctuations.......We present the first angle-resolved measurements of spatial photon correlations that are induced by multiple scattering of light. The correlation relates multiple scattered photons at different spatial positions and depends on incident photon fluctuations....

  5. Conservative treatment modalities in retinoblastoma

    Science.gov (United States)

    Chawla, Bhavna; Jain, Amit; Azad, Rajvardhan

    2013-01-01

    Retinoblastoma is the most common primary intraocular malignancy of childhood. A potentially curable cancer, its treatment has improved significantly over the last few decades. The purpose of this article is to review the literature on various conservative treatment modalities available for the treatment of retinoblastoma and their effectiveness, when used alone or in combination. Pubmed, Medline, Embase, and the Cochrane library were searched through 2012 for published peer reviewed data on conservative treatment modalities for retinoblastoma. Various studies show that while enucleation remains the standard of care for advanced intraocular tumors, conservative modalities that can result in globe salvage and preservation of useful vision are being increasingly employed. Such modalities include systemic chemotherapy, focal consolidation with transpupillary thermotherapy, laser photocoagulation and cryotherapy, plaque brachytherapy, and delivery of local chemotherapy using subconjunctival, sub-tenon, or intra-arterial routes. When used alone or in combination, these treatment modalities can help in avoidance of external beam radiotherapy or enucleation, thus reducing the potential for long-term side effects, while salvaging useful vision. Radioactive plaque brachytherapy has an established role in selected patients with intraocular retinoblastoma. Local injections of chemotherapeutic agents via the sub-tenon or sub-conjunctival route have been used with varying degrees of success, usually as an adjunct to systemic chemotherapy. Intra-arterial ophthalmic artery delivery of melphalan has shown promising results. It is important to recognize that today, several treatment options are available that can obviate the need for enucleation, and cure the cancer with preservation of functional vision. A thorough knowledge and understanding of these conservative treatment modalities is essential for appropriate management. PMID:24104705

  6. Conservative treatment modalities in retinoblastoma

    Directory of Open Access Journals (Sweden)

    Bhavna Chawla

    2013-01-01

    Full Text Available Retinoblastoma is the most common primary intraocular malignancy of childhood. A potentially curable cancer, its treatment has improved significantly over the last few decades. The purpose of this article is to review the literature on various conservative treatment modalities available for the treatment of retinoblastoma and their effectiveness, when used alone or in combination. Pubmed, Medline, Embase, and the Cochrane library were searched through 2012 for published peer reviewed data on conservative treatment modalities for retinoblastoma. Various studies show that while enucleation remains the standard of care for advanced intraocular tumors, conservative modalities that can result in globe salvage and preservation of useful vision are being increasingly employed. Such modalities include systemic chemotherapy, focal consolidation with transpupillary thermotherapy, laser photocoagulation and cryotherapy, plaque brachytherapy, and delivery of local chemotherapy using subconjunctival, sub-tenon, or intra-arterial routes. When used alone or in combination, these treatment modalities can help in avoidance of external beam radiotherapy or enucleation, thus reducing the potential for long-term side effects, while salvaging useful vision. Radioactive plaque brachytherapy has an established role in selected patients with intraocular retinoblastoma. Local injections of chemotherapeutic agents via the sub-tenon or sub-conjunctival route have been used with varying degrees of success, usually as an adjunct to systemic chemotherapy. Intra-arterial ophthalmic artery delivery of melphalan has shown promising results. It is important to recognize that today, several treatment options are available that can obviate the need for enucleation, and cure the cancer with preservation of functional vision. A thorough knowledge and understanding of these conservative treatment modalities is essential for appropriate management.

  7. Scattering by two spheres: Theory and experiment

    DEFF Research Database (Denmark)

    Bjørnø, Irina; Jensen, Leif Bjørnø

    1998-01-01

    on three issues: (1) to develop a simplified theory for scattering by two elastical spheres; (2) to measure the scattering by two spheres in a water tank, and (3) to compare the theoretical/numerical results with the measured data. A number of factors influencing multiple scattering, including...

  8. Quasielastic Neutron Scattering by Superionic Strontium Chloride

    DEFF Research Database (Denmark)

    Dickens, M. H.; Hutchings, M. T.; Kjems, Jørgen

    1978-01-01

    The scattering, from powder and single crystal samples, appears only above the superionic transition temperature, 1000K. The integrated intensity is found to be strongly dependent on the direction and magnitude of the scattering vector, Q, (which suggests the scattering is coherent) but does not ...

  9. Classical and quantum scattering in optical systems

    NARCIS (Netherlands)

    Puentes, Graciana

    2007-01-01

    The central topic of the Thesis concerns light scattering experiments with entangled photons. Specifically, we study the effect of scattering processes on polarization-entanglement of twin-photons. The main idea is that scattering generally couples polarization and spatial degrees of freedom of

  10. Scattering amplitudes in gauge theories

    CERN Document Server

    Henn, Johannes M

    2014-01-01

    At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge.   These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum ...

  11. Scattering of muonic hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Mulhauser, F. [Universite de Fribourg (Switzerland); Adamczak, A. [Institute of Nuclear Physics (Poland); Beer, G.A. [University of Victoria (Canada); Bystritsky, V.M. [Joint Institute for Nuclear Research (Russian Federation); Filipowicz, M. [Institute of Physics and Nuclear Techniques (Poland); Fujiwara, M.C. [University of British Columbia (Canada); Huber, T.M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [Universite de Fribourg (Switzerland); Kammel, P. [University of California (United States); Kim, S.K. [Jeonbuk National University (Korea, Republic of); Knowles, P. [Universite de Fribourg (Switzerland); Kunselman, A.R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V.E. [Paul Scherrer Institute (Switzerland); Marshall, G.M. [TRIUMF (Canada); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T.A. [University of Victoria (Canada); Stolupin, V.A. [Joint Institute for Nuclear Research (Russian Federation); Wozniak, J. [Institute of Physics and Nuclear Techniques (Poland)] (and others)

    1999-06-15

    Our measurement compares the energy dependence of the scattering cross-sections of muonic deuterium and tritium on hydrogen molecules for collisions in the energy range 0.1-45 eV. A time-of-flight method was used to measure the scattering cross-section as a function of the muonic atom beam energy and shows clearly the Ramsauer-Townsend effect. The results are compared with theoretical calculations by using Monte Carlo simulations. The molecular pd{mu} and pt{mu} formation creates background processes. We measure the formation rates in solid hydrogen by detecting the 5.5 MeV (pd{mu}) and 19.8 MeV (pt{mu}) {gamma}-rays emitted during the subsequent nuclear fusion processes.

  12. Scattering characteristics from porous silicon

    Directory of Open Access Journals (Sweden)

    R. Sabet-Dariani

    2000-12-01

    Full Text Available   Porous silicon (PS layers come into existance as a result of electrochemical anodization on silicon. Although a great deal of research has been done on the formation and optical properties of this material, the exact mechanism involved is not well-understood yet.   In this article, first, the optical properties of silicon and porous silicon are described. Then, previous research and the proposed models about reflection from PS and the origin of its photoluminescence are reveiwed. The reflecting and scattering, absorption and transmission of light from this material, are then investigated. These experiments include,different methods of PS sample preparation their photoluminescence, reflecting and scattering of light determining different characteristics with respect to Si bulk.

  13. Spectroscopy, scattering, and KK molecules

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J. [Univ. of Mississippi, University, MS (United States)

    1994-04-01

    The author presents a pedagogical description of a new theoretical technique, based on the multichannel Schroedinger equation, for simultaneously applying the quark model to both meson spectroscopy and meson-meson scattering. This is an extension of an earlier analysis which led to the prediction that the f{sub o}(975) and a{sub o}(980) scalar mesons are K{bar K} molecular states.

  14. Scattering from Foliage Covered Terrain.

    Science.gov (United States)

    1985-03-01

    approximate theories are derived from continuous random media theory while only a relatively few are based on the truly dis- S crete nature of the random media...The primary difficulty with trying to use continuous randon media theory for truly discrete media is that one is forced into defining a number of...scattering properties of an infinite half-space of foliage and a layer of foliage on a planar ground, respectively, using discrete ran- corn media theory . For

  15. Narrowband Compton Scattering Yield Enhancement

    Science.gov (United States)

    Rykovanov, Sergey; Seipt, Daniel; Kharin, Vasily

    2017-10-01

    Compton Scattering (CS) of laser light off high-energy electrons is a well-established source of X- and gamma-rays for applications in medicine, biology, nuclear and material sciences. Main advantage of CS photon sources is the possibility to generate narrow spectra as opposed to a broad continuum obtained when utilizing Bremsstrahlung. However, due to the low cross-section of the linear process, the total photon yield is quite low. The most straightforward way to increase the number of photon-electron beam scattering events is to increase the laser pulse intensity at the interaction point by harder focusing. This leads to an unfortunate consequence. Increase in the laser pulse normalized amplitude a0, leads to additional ponderomotive spectrum broadening of the scattered radiation. The ponderomotive broadening is caused by the v × B force, which slows the electron down near the peak of the laser pulse where the intensity is high, and can be neglected near the wings of the pulse, where the intensity is low. We show that laser pulse chirping, both nonlinear (laser pulse frequency ''following'' the envelope of the pulse) and linear, leads to compensation of the ponderomotive broadening and considerably enhances the yield of the nonlinear Compton sources. Work supported by the Helmholtz Association via Helmholtz Young Investigators Grant (VH-NG-1037).

  16. Rg propagation: Scatter versus Attenuation

    Science.gov (United States)

    Cleveland, M.; Phillips, W. S.; MacCarthy, J.

    2016-12-01

    At near local distances, the Rg seismic phase is often the largest seismic arrival for shallow sources. While Rg is classically defined for the period range of 8-12 s, we use the term generically to refer to short-period observations of Rayleigh waves from shallow sources [e.g. Langston, 1987; Bonner and Russell, 2013]. There is significant interest in using Rg as a basis for seismic discrimination and magnitude (e.g. Bonner and Russell, 2013). However, the propagation of this phase is poorly understood. At Nevada National Security Site, while Rg is well observed near the source, it quickly disappears at greater distances. This observation raises the fundamental question of how much of the Rg energy is simply attenuating versus scattering into other seismic phases. Understanding this is critical to interpreting not only the observed Rg seismic energy, but also the possible enrichment of other seismic phases resulting from Rg scattering. In this study, we use waveform data from the Bighorn Arch Seismic Experiment (BASE) and Source Physics Experiment (SPE) to investigate Rg propagation, looking to identify how much energy from the phase attenuates with distance and how much scatters into other seismic phases.

  17. Efeito do tratamento térmico na microestrutura, turbostraticidade e superfície de carbono vítreo reticulado analisado por XPS, espalhamento Raman e voltametria cíclica Thermal treatment effect on the microstructure, turbostraticity, and surface of reticulated vitreous carbon analyzed by xps, Raman scattering, and cyclic voltammetry

    Directory of Open Access Journals (Sweden)

    Emerson Sarmento Gonçalves

    2009-01-01

    Full Text Available The structural and surface properties of reticulated vitreous carbon (RVC were discussed as a function of its heat treatment temperature (HTT, for samples produced in the range from 700 to 2000 ºC, using the furfuryl precursor resin. The samples were analyzed by x-ray photoelectron spectroscopy, first and second order Raman scattering as well as electrochemical response. Exploring the material turbostraticity concept, the interdependence between the RVC chemical surface variation and its defects were demonstrated. The influence of heteroatom presence was discussed in the material ordering for HTT lower than 1300 ºC while the graphitization process evolution was also pointed out for HTT higher than 1500 ºC.

  18. Light Scattering Spectroscopy: From Elastic to Inelastic

    Science.gov (United States)

    Perelman, Lev T.; Modell, Mark D.; Vitkin, Edward; Hanlon, Eugene B.

    This chapter reviews light scattering spectroscopic techniques in which coherent effects are critical because they define the structure of the spectrum. In the case of elastic light scattering spectroscopy, the targets themselves, such as aerosol particles in environmental science or cells and subcellular organelles in biomedical applications, play the role of microscopic optical resonators. In the case of inelastic light scattering spectroscopy or Raman spectroscopy, the spectrum is created due to light scattering from vibrations in molecules or optical phonons in solids. We will show that light scattering spectroscopic techniques, both elastic and inelastic, are emerging as very useful tools in material and environmental science and in biomedicine.

  19. Scattering theory of stochastic electromagnetic light waves.

    Science.gov (United States)

    Wang, Tao; Zhao, Daomu

    2010-07-15

    We generalize scattering theory to stochastic electromagnetic light waves. It is shown that when a stochastic electromagnetic light wave is scattered from a medium, the properties of the scattered field can be characterized by a 3 x 3 cross-spectral density matrix. An example of scattering of a spatially coherent electromagnetic light wave from a deterministic medium is discussed. Some interesting phenomena emerge, including the changes of the spectral degree of coherence and of the spectral degree of polarization of the scattered field.

  20. Wave propagation and scattering in random media

    CERN Document Server

    Ishimaru, Akira

    1978-01-01

    Wave Propagation and Scattering in Random Media, Volume 2, presents the fundamental formulations of wave propagation and scattering in random media in a unified and systematic manner. The topics covered in this book may be grouped into three categories: waves in random scatterers, waves in random continua, and rough surface scattering. Random scatterers are random distributions of many particles. Examples are rain, fog, smog, hail, ocean particles, red blood cells, polymers, and other particles in a state of Brownian motion. Random continua are the media whose characteristics vary randomly an

  1. Multiphoton Scattering Tomography with Coherent States.

    Science.gov (United States)

    Ramos, Tomás; García-Ripoll, Juan José

    2017-10-13

    In this work we develop an experimental procedure to interrogate the single- and multiphoton scattering matrices of an unknown quantum system interacting with propagating photons. Our proposal requires coherent state laser or microwave inputs and homodyne detection at the scatterer's output, and provides simultaneous information about multiple-elastic and inelastic-segments of the scattering matrix. The method is resilient to detector noise and its errors can be made arbitrarily small by combining experiments at various laser powers. Finally, we show that the tomography of scattering has to be performed using pulsed lasers to efficiently gather information about the nonlinear processes in the scatterer.

  2. Mechanism of nuclear rainbow scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ohkubo, S. [Department of Applied Science and Environment, Kochi Women University, Kochi 780-8515 (Japan)

    2001-09-01

    Full text: Nuclear rainbow phenomenon has been widely observed in light heavy ion scattering such as {sup 16} 0 + {sup 16} 0, {sup 16} 0 + {sup 12} C and {sup 12} C + {sup 12} C and great progress has been made experimentally and theoretically especially in the nineties. The nuclear rainbow has been understood quite often in analogy to meteorological rainbow caused by scattering of light from water droplets, because they are both considered to be a refractive phenomenon. Traditionally nuclear rain- bow has been explained by the far side component of the scattering amplitudes in the presence of a strong attractive force: The observed Airy structure in the angular distributions has been understood by the interference between it's two sub amplitudes in analogy to the interference of two refractive waves in meteorological rainbow, although it was not easy to theoretically extract its components separately. By studying the {sup 16} 0 + {sup 16} 0 scattering measured at Strasbourg, we have theoretically succeeded in extracting the sub amplitudes of the far side scattering in a rigorous but easy way: the sub amplitudes are obtained by decomposing the calculated scattering amplitude into its internal wave and barrier wave components. It is found that the Airy structure observed in the angular distributions in the E L = 75-145 MeV is caused by the interference between the far side internal-wave and far side barrier-wave. The minima in the 90-excitation function, which has been interpreted to be the passage of the Airy elephants, can also be explained as the interference between the far side internal- wave and barrier-wave. It is noted that although the internal wave is a refracted wave the barrier wave is a reflected wave, which does not feel the attractive potential in the very internal region. This means that the nuclear Airy structure is caused by the interference between the refractive wave and reflective wave. This finding is very different from the traditional

  3. Evaluation of beam hardening and photon scatter by brass compensator for IMRT.

    Science.gov (United States)

    Hashimoto, Shimpei; Karasawa, Katsuyuki; Fujita, Yukio; Miyashita, Hisayuki; Chang, Weishan; Kawachi, Toru; Katayose, Tetsurou; Kobayashi, Nao; Kunieda, Etsuo; Saitoh, Hidetoshi

    2012-11-01

    When a brass compensator is set in a treatment beam, beam hardening may take place. This variation of the energy spectrum may affect the accuracy of dose calculation by a treatment planning system and the results of dose measurement of brass compensator intensity modulated radiation therapy (IMRT). In addition, when X-rays pass the compensator, scattered photons are generated within the compensator. Scattered photons may affect the monitor unit (MU) calculation. In this study, to evaluate the variation of dose distribution by the compensator, dose distribution was measured and energy spectrum was simulated using the Monte Carlo method. To investigate the influence of beam hardening for dose measurement using an ionization chamber, the beam quality correction factor was determined. Moreover, to clarify the effect of scattered photons generated within the compensator for the MU calculation, the head scatter factor was measured and energy spectrum analyses were performed. As a result, when X-rays passed the brass compensator, beam hardening occurred and dose distribution was varied. The variation of dose distribution and energy spectrum was larger with decreasing field size. This means that energy spectrum should be reproduced correctly to obtain high accuracy of dose calculation for the compensator IMRT. On the other hand, the influence of beam hardening on k(Q) was insignificant. Furthermore, scattered photons were generated within the compensator, and scattered photons affect the head scatter factor. These results show that scattered photons must be taken into account for MU calculation for brass compensator IMRT.

  4. PREFACE: Atom-surface scattering Atom-surface scattering

    Science.gov (United States)

    Miret-Artés, Salvador

    2010-08-01

    It has been a privilege and a real pleasure to organize this special issue or festschrift in the general field of atom-surface scattering (and its interaction) in honor of J R Manson. This is a good opportunity and an ideal place to express our deep gratitude to one of the leaders in this field for his fundamental and outstanding scientific contributions. J R Manson, or Dick to his friends and colleagues, is one of the founding fathers, together with N Cabrera and V Celli, of the 'Theory of surface scattering and detection of surface phonons'. This is the title of the very well-known first theoretical paper by Dick published in Physical Review Letters in 1969. My first meeting with Dick was around twenty years ago in Saclay. J Lapujoulade organized a small group seminar about selective adsorption resonances in metal vicinal surfaces. We discussed this important issue in surface physics and many other things as if we had always known each other. This familiarity and warm welcome struck me from the very beginning. During the coming years, I found this to be a very attractive aspect of his personality. During my stays in Göttingen, we had the opportunity to talk widely about science and life at lunch or dinner time, walking or cycling. During these nice meetings, he showed, with humility, an impressive cultural background. It is quite clear that his personal opinions about history, religion, politics, music, etc, come from considering and analyzing them as 'open dynamical systems'. In particular, with good food and better wine in a restaurant or at home, a happy cheerful soirée is guaranteed with him, or even with only a good beer or espresso, and an interesting conversation arises naturally. He likes to listen before speaking. Probably not many people know his interest in tractors. He has an incredible collection of very old tractors at home. In one of my visits to Clemson, he showed me the collection, explaining to me in great detail, their technical properties

  5. Eliminating electromagnetic scattering from small particles

    CERN Document Server

    Vehmas, Joni; Karilainen, Antti; Tretyakov, Sergei

    2012-01-01

    This paper presents and discusses the conditions for zero electromagnetic scattering by electrically small particles. We consider the most general bi-anisotropic particles, characterized by four dyadic polarizabilities and study the case of uniaxially symmetric objects. Conditions for zero backward and forward scattering are found for a general uniaxial bi-anisotropic particle and specialized for all fundamental classes of bi-anisotropic particles: omega, "moving", chiral, and Tellegen particles. Possibility for zero total scattering is also discussed for aforementioned cases. The scattering pattern and polarization of the scattered wave are also determined for each particle class. In particular, we analyze the interplay between different scattering mechanisms and show that in some cases it is possible to compensate scattering from a polarizable particle by appropriate magneto-electric coupling.

  6. Positronium and Electron Scattering on Helium

    Science.gov (United States)

    DiRienzi, Joseph

    2011-01-01

    A recent work [1] establishes experimentally that Positronium scattering by atoms of various elements is surprisingly close in total cross-section to that of an isolated electron of the same velocity. In this work we will look at the scattering of Ps on Helium and compare it to a determination of the scattering of an e- with the same element. For both the Ps scattering and the e- scattering on He, we assume the symmetrization of the e- with the closed shell He electrons is the dominant interaction. A local effective potential employed in [2] and [3] is used to model the electron exchange and cross- sections are determined for a set of partial waves. For the Ps scattering we include as a secondary effect the Van der Waals interaction. For single e- scattering of He, we also employ a short range Coulomb potential and dispersion as contributing effects. Results of the cross-sections determined in each case are then compared

  7. Room scatter effects in Total Skin Electron Irradiation: Monte Carlo simulation study.

    Science.gov (United States)

    Nevelsky, Alexander; Borzov, Egor; Daniel, Shahar; Bar-Deroma, Raquel

    2017-01-01

    Total Skin Electron Irradiation (TSEI) is a complex technique which usually involves the use of large electron fields and the dual-field approach. In this situation, many electrons scattered from the treatment room floor are produced. However, no investigations of the effect of scattered electrons in TSEI treatments have been reported. The purpose of this work was to study the contribution of floor scattered electrons to skin dose during TSEI treatment using Monte Carlo (MC) simulations. All MC simulations were performed with the EGSnrc code. Influence of beam energy, dual-field angle, and floor material on the contribution of floor scatter was investigated. Spectrum of the scattered electrons was calculated. Measurements of dose profile were performed in order to verify MC calculations. Floor scatter dependency on the floor material was observed (at 20 cm from the floor, scatter contribution was about 21%, 18%, 15%, and 12% for iron, concrete, PVC, and water, respectively). Although total dose profiles exhibited slight variation as functions of beam energy and dual-field angle, no dependence of the floor scatter contribution on the beam energy or dual-field angle was found. The spectrum of the scattered electrons was almost uniform between a few hundred KeV to 4 MeV, and then decreased linearly to 6 MeV. For the TSEI technique, dose contribution due to the electrons scattered from the room floor may be clinically significant and should be taken into account during design and commissioning phases. MC calculations can be used for this task. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  8. Current Treatments of Diabetic Macular Edema

    Directory of Open Access Journals (Sweden)

    Wei-Chun Chan

    2011-12-01

    Full Text Available Diabetic macular edema (DME is a major cause of visual impairment in diabetic patients. Laser photocoagulation is the standard management strategy for macular edema, but its results remain unsatisfactory. Several clinical trials of new treatment modalities for DME have been conducted over the past 10 years. We performed a literature search of English articles, published between 2000 and 2010, by using the PubMed database. The keywords searched included “diabetic macular edema and treatment” with limits set to include only clinical trials and review articles, over 50 articles were reviewed. Among the newer treatment modalities reviewed, therapy with anti-vascular endothelial growth factor (VEGF antibodies showed significantly better efficacy, with level I evidence. However, multiple injections were required to maintain its efficacy. Therefore, the associated complications and cost implications are the major limitations of this treatment. Several combinations of different modalities have been evaluated in the literature, but none are more efficacious than monotherapy with anti-VEGF antibodies. Since DME is a multifactorial disease, further studies involving combinations of modalities or new treatments modalities may be needed to reduce the number of injections required or improve the visual outcomes in case of DME.

  9. Light scattering near phase transitions

    CERN Document Server

    Cummins, HZ

    1983-01-01

    Since the development of the laser in the early 1960's, light scattering has played an increasingly crucial role in the investigation of many types of phase transitions and the published work in this field is now widely dispersed in a large number of books and journals.A comprehensive overview of contemporary theoretical and experimental research in this field is presented here. The reviews are written by authors who have actively contributed to the developments that have taken place in both Eastern and Western countries.

  10. Barrier distributions from elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, N. [Manchester Univ. (United Kingdom). Dept. of Physics]|[Surrey Univ., Guildford (United Kingdom). Dept. of Physics; Timmers, H.; Leigh, J.R.; Masgupta, M.; Hinde, D.J.; Mein, J.C.; Morton, C.R.; Newton, J.O. [Australian National Univ., Canberra, ACT (Australia). Dept. of Nuclear Physics

    1996-01-01

    A new representation of the distribution of potential barriers present in heavy ion reactions is defined in terms of the elastic scattering excitation function. Its validity is demonstrated for the systems {sup 16}0 + {sup 144,} {sup 154}Sm, {sup 186}W, {sup 208}Pb, for which precise measurements have been made. Compared with fusion barrier distributions, which show structures characteristic of collective inelastic couplings, the elastic distributions are less detailed. This appears to be due to couplings to weaker direct reaction channels. 20 refs., 3 figs.

  11. Compton scattering on $^{208}$Pb

    CERN Document Server

    Alberico, W M

    1982-01-01

    The authors briefly review the formalism of the nuclear Compton scattering in the frame of the low-energy theorems (LET). They treat the resonant terms of the amplitude, having collective intermediate nuclear states, as a superposition of Lorentz lines with energy, width and strength fixed by the photo-absorption experiments. The gauge terms are evaluated starting from a simple, but realistic, nuclear Hamiltonian. Dynamical nucleon-nucleon correlations are consistently taken into account, beyond those imposed by the Pauli principle. The comparison of the theoretical predictions with the data of elastic diffusion of photons from /sup 208/Pb shows that LET are insufficient to account for the experiment.

  12. Small angle scattering and polymers

    Energy Technology Data Exchange (ETDEWEB)

    Cotton, J.P. [Laboratoire Leon Brillouin (LLB) - Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1996-12-31

    The determination of polymer structure is a problem of interest for both statistical physics and industrial applications. The average polymer structure is defined. Then, it is shown why small angle scattering, associated with isotopic substitution, is very well suited to the measurement of the chain conformation. The corresponding example is the old, but pedagogic, measurement of the chain form factor in the polymer melt. The powerful contrast variation method is illustrated by a recent determination of the concentration profile of a polymer interface. (author) 12 figs., 48 refs.

  13. New Techniques in Neutron Scattering

    DEFF Research Database (Denmark)

    Birk, Jonas Okkels

    Neutron scattering is an important experimental technique in amongst others solid state physics, biophysics, and engineering. This year construction of European Spallation Source (ESS) was commenced in Lund, Sweeden. The facility will use a new long pulsed source principle to obtain higher....... The instrument is ideally suited for solid state experiments with extreme sample environments such as large pressures and strong magnetic fields. CAMEA combines the time-of-flight technique to determine the energy of the incoming neutrons with a complex multiplex backend that will analyse and detect...

  14. Hadron scattering, resonances, and QCD

    Energy Technology Data Exchange (ETDEWEB)

    Briceno, Raul [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-12-01

    The non-perturbative nature of quantum chromodynamics (QCD) has historically left a gap in our understanding of the connection between the fundamental theory of the strong interactions and the rich structure of experimentally observed phenomena. For the simplest properties of stable hadrons, this is now circumvented with the use of lattice QCD (LQCD). In this talk I discuss a path towards a rigorous determination of few-hadron observables from LQCD. I illustrate the power of the methodology by presenting recently determined scattering amplitudes in the light-meson sector and their resonance content.

  15. Scattering amplitudes in open superstring theory

    Energy Technology Data Exchange (ETDEWEB)

    Schlotterer, Oliver

    2011-07-15

    The present thesis deals with the theme field of the scattering amplitudes in theories of open superstrings. Especially two different formalisms for the handling of superstrings are introduced and applied for the calaculation of tree-level amplitudes - the Ramond- Neveu-Schwarz (RNS) and the Pure-Spinor (PS) formalism. The RNS approach is proved as flexible in order to describe compactification of the initially ten flat space-time dimensions to four dimensions. We solve the technical problems, which result from the interacting basing world-sheet theory with conformal symmetry. This is used to calculate phenomenologically relevant scattering amplitudes of gluons and quarks as well as production rates of massive harmonic vibrations, which were already identified as virtual exchange particles on the massless level. In the case of a low string mass scale in the range of some Tev the string-specific signatures in parton collisions can be observed in the near future in the LHC experiment at CERN and indicated as first experimental proof of the string theory. THose string effects occur universally for a wide class of string ground states respectively internal geometries and represent an elegant way to avoid the so-called landscape problem of the string theory. A further theme complex in this thesis is based on the PS formalism, which allows a manifestly supersymmetric treatment of scattering amplitudes in ten space-time dimension with sixteen supercharges. We introduce a family of superfields, which occur in massless amplitudes of the open string and can be naturally identified with diagrams of three-valued knots. Thereby we reach not only a compact superspace representation of the n-point field-theory amplitude but can also write the complete superstring n-point amplitude as minimal linear combination of partial amplitudes of the field theory as well as hypergeometric functions. The latter carry the string effects and are analyzed from different perspectives, above all

  16. Benign Spine Lesions: Advances in Techniques for Minimally Invasive Percutaneous Treatment.

    Science.gov (United States)

    Tomasian, A; Wallace, A N; Jennings, J W

    2017-05-01

    Minimally invasive percutaneous imaging-guided techniques have been shown to be safe and effective for the treatment of benign tumors of the spine. Techniques available include a variety of tumor ablation technologies, including radiofrequency ablation, cryoablation, microwave ablation, alcohol ablation, and laser photocoagulation. Vertebral augmentation may be performed after ablation as part of the same procedure for fracture stabilization or prevention. Typically, the treatment goal in benign spine lesions is definitive cure. Painful benign spine lesions commonly encountered in daily practice include osteoid osteoma, osteoblastoma, vertebral hemangioma, aneurysmal bone cyst, Paget disease, and subacute/chronic Schmorl node. This review discusses the most recent advancement and use of minimally invasive percutaneous therapeutic options for the management of benign spine lesions. © 2017 by American Journal of Neuroradiology.

  17. Introduction to ground penetrating radar inverse scattering and data processing

    CERN Document Server

    Persico, Raffaele

    2014-01-01

    This book presents a comprehensive treatment of ground penetrating radar using both forward and inverse scattering mathematical techniques. Use of field data instead of laboratory data enables readers to envision real-life underground imaging; a full color insert further clarifies understanding. Along with considering the practical problem of achieving interpretable underground images, this book also features significant coverage of the problem's mathematical background. This twofold approach provides a resource that will appeal both to application oriented geologists and testing specialists,

  18. Scattering amplitudes in gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Henn, Johannes M. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Plefka, Jan C. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2014-03-01

    First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.

  19. Intrabeam scattering in the LHC

    CERN Document Server

    Mertens, Tom; Sousa Da Costa, Miguel

    2011-01-01

    Intrabeam Scattering (IBS) is the process where particles within an accelerator beam elastically scatter off each other. The effect of IBS is not to be confused with the Coulomb repulsion due to the fields generated by the other particles in the beam. The Coulomb repulsion effects are referred to as space-charge effects in Accelerator Physics and become less important than IBS at high energies because of the 1/gamma^2 that occurs in the space-charge equations making IBS one of the most important causes of beam size growth. At high energies (for example at 7 TeV or the LHC nominal operation energy) IBS effects are counteracted by Radiation Damping effects, in some cases leading to decrease in beam sizes instead of beam growth. But at the time of writing the operation energies were still low enough to neglect Radiation Damping Effects in comparison with IBS effects (Radiation Lifetimes were a factor five to ten higher than the IBS Lifetimes in the cases presented at the end of this text). Because of its effect ...

  20. Optical Sensors Using Stimulated Brillouin Scattering

    Science.gov (United States)

    Christensen, Caleb A (Inventor); Zavriyev, Anton (Inventor)

    2017-01-01

    A method for enhancing a sensitivity of an optical sensor having an optical cavity counter-propagates beams of pump light within the optical cavity to produce scattered light based on Stimulated Brillouin Scattering (SBS). The properties of the pump light are selected to generate fast-light conditions for the scattered light, such that the scattered light includes counter-propagating beams of fast light. The method prevents the pump light from resonating within the optical cavity, while allowing the scattered light to resonate within the optical cavity. At least portions of the scattered light are interfered outside of the optical cavity to produce a beat note for a measurement of the optical sensor. The disclosed method is particularly applicable to optical gyroscopes.

  1. Scattering of acoustic waves by small crustaceans

    Science.gov (United States)

    Andreeva, I. B.; Tarasov, L. L.

    2003-03-01

    Features of underwater sound scattering by small crustaceans are considered. The scattering data are obtained with the use of unique instrumentation that allows one to measure quantitative scattering characteristics (backscattering cross sections and angular scattering patterns) for crustaceans of different sizes, at different frequencies (20 200 kHz) and different insonification aspects. A computational model of crustaceans is considered with allowance for both the soft tissues of the main massive part of the animal's body and the stiff armour. The model proves to be advantageous for explaining some scattering features observed in the experiments. The scattering cross sections of crustaceans measured by other researchers are presented in a unified form appropriate for comparison. Based on such a quantitative comparison, relatively simple approximate empirical formulas are proposed for estimating the backscattering cross sections of small (within several centimeters) marine crustaceans in a broad frequency range.

  2. Scattering from isotropic plasma coated nihility sphere

    Science.gov (United States)

    Hussan, M. M.; Ghaffar, A.; Alkanhal, Majeed A. S.; Naz, M. Y.; Ur Rehman, Sajjad; Khan, Y.

    2017-06-01

    In this study, it is observed that when an isotropic collisional plasma coating layer is produced on a nihility sphere, its back scattering efficiency becomes non-zero. Field equations, at each interface, are expanded in terms of spherical wave vector functions (SWVFs) by enforcing the extended classical wave scattering theory. Electromagnetic boundary conditions are applied at both interfaces, i.e., free space-plasma and plasma layer-nihility sphere core to obtain the scattering coefficients. The obtained scattering coefficients are used to calculate the forward scattering, back scattering, and extinction efficiencies. The obtained computational results show that an increase in collisional frequency causes a decrease in both forward and backscattered efficiencies and an increase in extinction efficiency. Furthermore, the numerical results indicate that an increase in plasma density causes an increase in both forward and backscattered efficiencies and a decrease in extinction efficiency.

  3. Large momentum transfer scattering and hadronic bremsstrahlung

    CERN Document Server

    Blankenbecler, Richard

    1975-01-01

    The interchange theory provides a simple picture of large momentum transfer scattering which correlates many features of hadrons and their interactions. It is simple to compute and has considerable predictive power. It unites the electromagnetic structure of hadrons as expressed through their form factors and inelastic structure functions with elastic and inelastic hadron-hadron scattering. The theory joins smoothly onto Regge behavior which controls forward scattering and in fact predicts such behaviour. The unified description of large and small momentum transfer scattering provided by the interchange model should allow considerable insight into the interaction of hadrons and their possible composite nature. It already yields a remarkably simple quantitative description which seems valid all the way from large angle elastic scattering at 5 GeV/c to inclusive scattering at the CERN-ISR. (13 refs).

  4. Optical phantoms with adjustable subdiffusive scattering parameters

    Science.gov (United States)

    Krauter, Philipp; Nothelfer, Steffen; Bodenschatz, Nico; Simon, Emanuel; Stocker, Sabrina; Foschum, Florian; Kienle, Alwin

    2015-10-01

    A new epoxy-resin-based optical phantom system with adjustable subdiffusive scattering parameters is presented along with measurements of the intrinsic absorption, scattering, fluorescence, and refractive index of the matrix material. Both an aluminium oxide powder and a titanium dioxide dispersion were used as scattering agents and we present measurements of their scattering and reduced scattering coefficients. A method is theoretically described for a mixture of both scattering agents to obtain continuously adjustable anisotropy values g between 0.65 and 0.9 and values of the phase function parameter γ in the range of 1.4 to 2.2. Furthermore, we show absorption spectra for a set of pigments that can be added to achieve particular absorption characteristics. By additional analysis of the aging, a fully characterized phantom system is obtained with the novelty of g and γ parameter adjustment.

  5. An electrical analogy to Mie scattering.

    Science.gov (United States)

    Caridad, José M; Connaughton, Stephen; Ott, Christian; Weber, Heiko B; Krstić, Vojislav

    2016-09-27

    Mie scattering is an optical phenomenon that appears when electromagnetic waves, in particular light, are elastically scattered at a spherical or cylindrical object. A transfer of this phenomenon onto electron states in ballistic graphene has been proposed theoretically, assuming a well-defined incident wave scattered by a perfectly cylindrical nanometer scaled potential, but experimental fingerprints are lacking. We present an experimental demonstration of an electrical analogue to Mie scattering by using graphene as a conductor, and circular potentials arranged in a square two-dimensional array. The tabletop experiment is carried out under seemingly unfavourable conditions of diffusive transport at room-temperature. Nonetheless, when a canted arrangement of the array with respect to the incident current is chosen, cascaded Mie scattering results robustly in a transverse voltage. Its response on electrostatic gating and variation of potentials convincingly underscores Mie scattering as underlying mechanism. The findings presented here encourage the design of functional electronic metamaterials.

  6. Neutron–19C scattering: Towards including realistic interactions

    Directory of Open Access Journals (Sweden)

    A. Deltuva

    2017-09-01

    Full Text Available Low-energy neutron–C19 scattering is studied in the three-body n+n+C18 model using a realistic nn potential and a number of shallow and deep n–C18 potentials, the latter supporting deeply-bound Pauli-forbidden states that are projected out. Exact Faddeev-type three-body scattering equations for transition operators including two- and three-body forces are solved in the momentum-space partial-wave framework. Phase shift, inelasticity parameter, and cross sections are calculated. For the elastic n–C19 scattering in the JΠ=0+ partial wave the signatures of the Efimov physics, i.e., the pole in the effective-range expansion and the elastic cross section minimum, are confirmed for both shallow and deep models, but with clear quantitative differences between them, indicating the importance of a proper treatment of deeply-bound Pauli-forbidden states. In contrast, the inelasticity parameter is mostly correlated with the asymptotic normalization coefficient of the C19 bound state. Finally, in the regime of very weak C19 binding and near-threshold (bound or virtual excited C20 state the standard Efimovian behaviour of the n–C19 scattering length and cross section was confirmed, resolving the discrepancies between earlier studies by other authors (Mazumdar et al., 2006 [20], Yamashita et al., 2007 [23].

  7. Neutron-19C scattering: Towards including realistic interactions

    Science.gov (United States)

    Deltuva, A.

    2017-09-01

    Low-energy neutron-19C scattering is studied in the three-body n + n +18C model using a realistic nn potential and a number of shallow and deep n-18C potentials, the latter supporting deeply-bound Pauli-forbidden states that are projected out. Exact Faddeev-type three-body scattering equations for transition operators including two- and three-body forces are solved in the momentum-space partial-wave framework. Phase shift, inelasticity parameter, and cross sections are calculated. For the elastic n-19C scattering in the JΠ =0+ partial wave the signatures of the Efimov physics, i.e., the pole in the effective-range expansion and the elastic cross section minimum, are confirmed for both shallow and deep models, but with clear quantitative differences between them, indicating the importance of a proper treatment of deeply-bound Pauli-forbidden states. In contrast, the inelasticity parameter is mostly correlated with the asymptotic normalization coefficient of the 19C bound state. Finally, in the regime of very weak 19C binding and near-threshold (bound or virtual) excited 20C state the standard Efimovian behaviour of the n-19C scattering length and cross section was confirmed, resolving the discrepancies between earlier studies by other authors (Mazumdar et al., 2006 [20], Yamashita et al., 2007 [23]).

  8. Current treatments for radiation retinopathy

    Energy Technology Data Exchange (ETDEWEB)

    Giuliari, Gian Paolo; Simpson, E. Rand (Princess Margaret Hospital, Univ. of Toronto, Dept. of Ophthalmology and Vision Sciences, Toronto (Canada)), e-mail: gpgiuliari@gmail.com; Sadaka, Ama (Schepens Eye Research Inst., Boston, MA (United States)); Hinkle, David M. (Massachusetts Eye Research and Surgery Institution, Cambridge, MA (United States))

    2011-01-15

    Background. To review the currently available therapeutic modalities for radiation retinopathy (RR), including newer investigational interventions directed towards specific aspects of the pathophysiology of this refractory complication. Methods. A review of the literature encompassing the pathogenesis of RR and the current therapeutic modalities available was performed. Results. RR is a chronic and progressive condition that results from exposure to any source of radiation. It might be secondary to radiation treatment of intraocular tumors such as choroidal melanomas, retinoblastomas, and choroidal metastasis, or from unavoidable exposure to excessive radiation from the treatment of extraocular tumors like cephalic, nasopharyngeal, orbital, and paranasal malignancies. After the results of the Collaborative Ocular Melanoma Study, most of the choroidal melanomas are being treated with plaque brachytherapy increasing by that the incidence of this radiation complication. RR has been reported to occur in as many as 60% of eyes treated with plaque radiation, with higher rates associated with larger tumors. Initially, the condition manifests as a radiation vasculopathy clinically seen as microaneurysms and telangiectasis, with posterior development of retinal hard exudates and hemorrhages, macular edema, neovascularization and tractional retinal detachment. Regrettably, the management of these eyes remains limited. Photodynamic therapy, laser photocoagulation, oral pentoxyphylline and hyperbaric oxygen have been attempted as treatment modalities with inconclusive results. Intravitreal injections of anti-vascular endothelial growth factor such as bevacizumab, ranibizumab and pegaptanib sodium have been recently used, also with variable results. Discussion. RR is a common vision threatening complication following radiation therapy. The available therapeutic options are limited and show unsatisfactory results. Further large investigative studies are required for developing

  9. Full Boltzmann equations for leptogenesis including scattering

    CERN Document Server

    Hahn-Woernle, F; Wong, Y Y Y

    2009-01-01

    We study the evolution of a cosmological baryon asymmetry produced via leptogenesis by means of the full classical Boltzmann equations, without the assumption of kinetic equilibrium and including all quantum statistical factors. Beginning with the full mode equations we derive the usual equations of motion for the right-handed neutrino number density and integrated lepton asymmetry, and show explicitly the impact of each assumption on these quantities. For the first time, we investigate also the effects of scattering of the right-handed neutrino with the top quark to leading order in the Yukawa couplings by means of the full Boltzmann equations. We find that in our full Boltzmann treatment the final lepton asymmetry can be suppressed by as much as a factor of 1.5 in the weak wash-out regime (K1), the full Boltzmann treatment and the integrated approach give nearly identical final lepton asymmetries (within 10 % of each other at K>3). Finally, we show that the opposing effects of quantum statistics on decays/i...

  10. Semiclassical scattering amplitudes of dressed gravitons

    OpenAIRE

    Kang, Kyungsik; Kondrashuk, Igor

    2004-01-01

    We consider effective action for the Einstein gravity and show that dressed mean fields are actual variables of the effective action. Kernels of this effective action expressed in terms of dressed effective fields are constituent parts of scattering amplitudes for gravitons. Possible applications to the graviton scattering and black hole formation are discussed at the semiclassical level. In particular, we consider graviton scattering in four dimensions based on the Lipatov effective action f...

  11. Coulomb correction to elastic. alpha. -. alpha. scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bera, P.K.; Jana, A.K.; Haque, N.; Talukdar, B. (Department of Physics, Visva-Bharati University, Santiniketan-731235, West Bengal, India (IN))

    1991-02-01

    The elastic {alpha}-{alpha} scattering is treated within the framework of a generalized phase-function method (GPFM). This generalization consists in absorbing the effect of Coulomb interaction in the comparison functions for developing the phase equation. Based on values of scattering phase shifts computed by the present method, it is concluded that the GPFM provides an uncomplicated approach to rigorous Coulomb correction in the {alpha}-{alpha} scattering.

  12. Dispersion Relations in Scattering and Antenna Problems

    OpenAIRE

    Sohl, Christian

    2008-01-01

    This dissertation deals with physical bounds on scattering and absorption of acoustic and electromagnetic waves. A general dispersion relation or sum rule for the extinction cross section of such waves is derived from the holomorphic properties of the scattering amplitude in the forward direction. The derivation is based on the forward scattering theorem via certain Herglotz functions and their asymptotic expansions in the low-frequency and high-frequency regimes. The result states that, for ...

  13. Kaons and antiproton-nucleus scattering

    CERN Document Server

    Haque, S; Rahman, S N

    2003-01-01

    The elastic scattering of Kaons and antiprotons from several nuclei is studied in the framework of the generalized diffraction model due to Frahn and Venter. The systematics of reaction cross section and the standard nuclear radius, as given by the model, are discussed. The parameters obtained from the elastic scattering analyses are used, without any adjustment, to reproduce some inelastic scattering angular distributions and the corresponding deformation parameters are determined.

  14. Hierarchy in chaotic scattering in Hill's problem

    CERN Document Server

    Kovács, Z

    1997-01-01

    Hierarchic properties of chaotic scattering in a model of satellite encounters, studied first by Petit and Henon, are examined by decomposing the dwell time function and comparing scattering trajectories. The analysis reveals an (approximate) ternary organization in the chaotic set of bounded orbits and the presence of a stable island. The results can open the way for a calculation of global quantities characterizing the scattering process by using tools of the thermodynamic formalism.

  15. Circular Intensity Differential Scattering of chiral molecules

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, C.J.

    1980-12-01

    In this thesis a theory of the Circular Intensity Differential Scattering (CIDS) of chiral molecules as modelled by a helix oriented with respect to the direction of incidence of light is presented. It is shown that a necessary condition for the existence of CIDS is the presence of an asymmetric polarizability in the scatterer. The polarizability of the scatterer is assumed generally complex, so that both refractive and absorptive phenomena are taken into account.

  16. Scattering from Rock and Rock Outcrops

    Science.gov (United States)

    2015-09-30

    Scattering from Rock and Rock Outcrops Derek R. Olson The Pennsylvania State University Applied Research Laboratory, P.O. Box 30 State...In terms of target detection and classification, scattering from exposed rock on the seafloor, (i.e., individual rocks and rock outcrops) presents...levels, and other statistical measures of acoustic scattering from rocks and rock outcrops is therefore critical. Unfortunately (and curiously

  17. Representation theorems and Green's function retrieval for scattering in acoustic media.

    Science.gov (United States)

    Vasconcelos, Ivan; Snieder, Roel; Douma, Huub

    2009-09-01

    Reciprocity theorems for perturbed acoustic media are provided in the form of convolution- and correlation-type theorems. These reciprocity relations are particularly useful in the general treatment of both forward and inverse-scattering problems. Using Green's functions to describe perturbed and unperturbed waves in two distinct wave states, representation theorems for scattered waves are derived from the reciprocity relations. While the convolution-type theorems can be manipulated to obtain scattering integrals that are analogous to the Lippmann-Schwinger equation, the correlation-type theorems can be used to retrieve the scattering response of the medium by cross correlations. Unlike previous formulations of Green's function retrieval, the extraction of scattered-wave responses by cross correlations does not require energy equipartitioning. Allowing for uneven energy radiation brings experimental advantages to the retrieval of fields scattered by remote lossless and/or attenuative scatterers. These concepts are illustrated with a number of examples, including analytic solutions to a one-dimensional scattering problem, and a numerical example in the context of seismic waves recorded on the ocean bottom.

  18. Cloaking through cancellation of diffusive wave scattering

    Science.gov (United States)

    Chen, P. Y.; Guenneau, S.; Bağcı, H.; Salama, K. N.; Alù, A.

    2016-01-01

    A new cloaking mechanism, which makes enclosed objects invisible to diffusive photon density waves, is proposed. First, diffusive scattering from a basic core–shell geometry, which represents the cloaked structure, is studied. The conditions of scattering cancellation in a quasi-static scattering regime are derived. These allow for tailoring the diffusivity constant of the shell enclosing the object so that the fields scattered from the shell and the object cancel each other. This means that the photon flow outside the cloak behaves as if the cloaked object were not present. Diffusive light invisibility may have potential applications in hiding hot spots in infrared thermography or tissue imaging. PMID:27616925

  19. Charmed Meson Scattering from Lattice QCD

    CERN Document Server

    Moir, Graham

    2016-01-01

    State-of-the-art lattice QCD calculations of scattering amplitudes in coupled-channel $D\\pi$, $D\\eta$ and $D_{s}\\bar{K}$ scattering, as well elastic $DK$ scattering are discussed. The methodology employed allows a determination of the relevant poles in the scattering matrix, while also providing a measure of the coupling of each channel to a given pole. By investigating $S$, $P$ and $D$ wave interactions, the nature of states with $J^{P} = 0^{+}$, relevant for the $D^{*}_{0}(2400)$ and $D^{*}_{s0}(2317)$, as well as states with $J^{P} = 1^{-}, 2^{+}$ are discussed.

  20. Spontaneous Brillouin scattering in a microdroplet

    Science.gov (United States)

    Ching, S. C.; Leung, P. T.; Young, K.

    1990-05-01

    Spontaneous Brillouin scattering in a micrometer-sized liquid droplet is analyzed from first principles, using the spherical-wave normal-mode basis. Instead of the conservation of linear momentum, this interaction is governed by a selection rule due to the conservation of angular momentum. The Brillouin spectrum is then calculated, both for observation at a given angle and for the sum over all angles, and compared with scattering in a bulk medium. Special attention is paid to the case where the incident and scattered radiation fall on an electromagnetic resonance of the droplet. The analysis lays the foundation for formulating stimulated Brillouin scattering in the same system.

  1. Parallel QR Decomposition for Electromagnetic Scattering Problems

    National Research Council Canada - National Science Library

    Boleng, Jeff

    1997-01-01

    This report introduces a new parallel QR decomposition algorithm. Test results are presented for several problem sizes, numbers of processors, and data from the electromagnetic scattering problem domain...

  2. Forward Scattering of Loaded and Unloaded Antennas

    DEFF Research Database (Denmark)

    Gustafsson, Mats; Andersen, Jørgen Bach; Kristensson, Gerhard

    2012-01-01

    Forward scattering of antennas is related to antenna performance via the forward-scattering sum rule. The forward-scattering sum rule is an integral identity that shows that a weighted integral of the extinction cross section over all spectrum is proportional to the static polarizability...... of the antenna structure. Here, the forward-scattering sum rule is experimentally verified for loaded, short-circuit, and open-circuit cylindrical dipole antennas. It is also shown that the absorption efficiency cannot be greater than 1/2 for reciprocal linearly polarized lossless matched antennas...

  3. Compton scatter tomography in TOF-PET

    Science.gov (United States)

    Hemmati, Hamidreza; Kamali-Asl, Alireza; Ay, Mohammadreza; Ghafarian, Pardis

    2017-10-01

    Scatter coincidences contain hidden information about the activity distribution on the positron emission tomography (PET) imaging system. However, in conventional reconstruction, the scattered data cause the blurring of images and thus are estimated and subtracted from detected coincidences. List mode format provides a new aspect to use time of flight (TOF) and energy information of each coincidence in the reconstruction process. In this study, a novel approach is proposed to reconstruct activity distribution using the scattered data in the PET system. For each single scattering coincidence, a scattering angle can be determined by the recorded energy of the detected photons, and then possible locations of scattering can be calculated based on the scattering angle. Geometry equations show that these sites lie on two arcs in 2D mode or the surface of a prolate spheroid in 3D mode, passing through the pair of detector elements. The proposed method uses a novel and flexible technique to estimate source origin locations from the possible scattering locations, using the TOF information. Evaluations were based on a Monte-Carlo simulation of uniform and non-uniform phantoms at different resolutions of time and detector energy. The results show that although the energy uncertainties deteriorate the image spatial resolution in the proposed method, the time resolution has more impact on image quality than the energy resolution. With progress of the TOF system, the reconstruction using the scattered data can be used in a complementary manner, or to improve image quality in the next generation of PET systems.

  4. Scatter corrections for cone beam optical CT

    Energy Technology Data Exchange (ETDEWEB)

    Olding, Tim; Holmes, Oliver [Department of Physics, Queen' s University (United Kingdom); Schreiner, L John [Medical Physics Department, Cancer Centre of Southeastern Ontario (Canada)], E-mail: Tim.Olding@krcc.on.ca

    2009-05-01

    Cone beam optical computed tomography (OptCT) employing the VISTA scanner (Modus Medical, London, ON) has been shown to have significant promise for fast, three dimensional imaging of polymer gel dosimeters. One distinct challenge with this approach arises from the combination of the cone beam geometry, a diffuse light source, and the scattering polymer gel media, which all contribute scatter signal that perturbs the accuracy of the scanner. Beam stop array (BSA), beam pass array (BPA) and anti-scatter polarizer correction methodologies have been employed to remove scatter signal from OptCT data. These approaches are investigated through the use of well-characterized phantom scattering solutions and irradiated polymer gel dosimeters. BSA corrected scatter solutions show good agreement in attenuation coefficient with the optically absorbing dye solutions, with considerable reduction of scatter-induced cupping artifact at high scattering concentrations. The application of BSA scatter corrections to a polymer gel dosimeter lead to an overall improvement in the number of pixel satisfying the (3%, 3mm) gamma value criteria from 7.8% to 0.15%.

  5. Hadron scattering and resonances in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, Jozef J. [Old Dominion Univ., Norfolk, VA (United States)

    2016-05-01

    I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study pi pi elastic scattering, including the rho resonance, as well as coupled-channel pi K, eta K scattering. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.

  6. Scattered UV irradiation during VISX excimer laser keratorefractive surgery.

    Science.gov (United States)

    Hope, R J; Weber, E D; Bower, K S; Pasternak, J P; Sliney, D H

    2008-04-01

    To evaluate the potential occupational health hazards associated with scattered ultraviolet (UV) radiation during photorefractive keratectomy (PRK) using the VISX Star S3 excimer laser. The Laser Vision Center, National Naval Medical Center, Bethesda, Maryland, USA. Intraoperative radiometric measurements were made with the Ophir Power/Energy Meter (LaserStar Model PD-10 with silicon detector) during PRK treatments as well as during required calibration procedures at a distance of 20.3 cm from the left cornea. These measurements were evaluated using a worst-case scenario for exposure, and then compared with the American Conference of Governmental Industrial Hygeinists (ACGIH) Threshold Value Limits (TVL) to perform a risk/hazard analysis. During the PRK procedures, the highest measured value was 248.4 nJ/pulse. During the calibration procedures, the highest measured UV scattered radiation level was 149.6 nJ/pulse. The maximum treatment time was 52 seconds. Using a worst-case scenario in which all treatments used the maximum power and time, the total energy per eye treated was 0.132 mJ/cm2 and the total UV radiation at close range (80 cm from the treated eye) was 0.0085 mJ/cm2. With a workload of 20 patients, the total occupational exposure at 80 cm to actinic UV radiation in an 8-hour period would be 0.425 mJ/cm2. The scattered actinic UV laser radiation from the VISX Star S3 excimer laser did not exceed occupational exposure limits during a busy 8-hour workday, provided that operating room personnel were at least 80 cm from the treated eye. While the use of protective eyewear is always prudent, this study demonstrates that the trace amounts of scattered laser emissions produced by this laser do not pose a serious health risk even without the use of protective eyewear.

  7. Grassmannian geometry of scattering amplitudes

    CERN Document Server

    Arkani-Hamed, Nima; Cachazo, Freddy; Goncharov, Alexander; Postnikov, Alexander; Trnka, Jaroslav

    2016-01-01

    Outlining a revolutionary reformulation of the foundations of perturbative quantum field theory, this book is a self-contained and authoritative analysis of the application of this new formulation to the case of planar, maximally supersymmetric Yang–Mills theory. The book begins by deriving connections between scattering amplitudes and Grassmannian geometry from first principles before introducing novel physical and mathematical ideas in a systematic manner accessible to both physicists and mathematicians. The principle players in this process are on-shell functions which are closely related to certain sub-strata of Grassmannian manifolds called positroids - in terms of which the classification of on-shell functions and their relations becomes combinatorially manifest. This is an essential introduction to the geometry and combinatorics of the positroid stratification of the Grassmannian and an ideal text for advanced students and researchers working in the areas of field theory, high energy physics, and the...

  8. Scattering theory for Riemannian Laplacians

    DEFF Research Database (Denmark)

    Ito, Kenichi; Skibsted, Erik

    condition is certain bounds of derivatives up to order one of the trace of this quantity. These conditions are shown to be optimal for existence and completeness of a wave operator. Our theory does not involve prescribed asymptotic behaviour of the metric at infinity (like asymptotic Euclidean or hyperbolic......In this paper we introduce a notion of scattering theory for the Laplace-Beltrami operator on non-compact, connected and complete Riemannian manifolds. A principal condition is given by a certain positive lower bound of the second fundamental form of angular submanifolds at infinity. Another...... metrics studied previously in the literature). A consequence of the theory is spectral theory for the Laplace-Beltrami operator including identification of the continuous spectrum and absence of singular continuous spectrum....

  9. Neutron scattering and models : molybdenum.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.

    1999-05-26

    A comprehensive interpretation of the fast-neutron interaction with elemental and isotopic molybdenum at energies of {le} 30 MeV is given. New experimental elemental-scattering information over the incident energy range 4.5 {r_arrow} 10 MeV is presented. Spherical, vibrational and dispersive models are deduced and discussed, including isospin, energy-dependent and mass effects. The vibrational models are consistent with the ''Lane potential''. The importance of dispersion effects is noted. Dichotomies that exist in the literature are removed. The models are vehicles for fundamental physical investigations and for the provision of data for applied purposes. A ''regional'' molybdenum model is proposed. Finally, recommendations for future work are made.

  10. Critical review of NNbar scattering

    CERN Document Server

    Bradamante, Franco

    1999-01-01

    Nucleon-antinucleon scattering experiments carried out at LEAR are briefly reviewed. Differential cross-section data of high accuracy are now available at many energies, and for the first time also analysing power data and some data on spin correlation parameters. Excellent fits to the NNbar data base have been performed by the Nijmegen group, both with a phase-shift analysis and with a coupled-channel potential model. The high precision cross section data from experiment PS206 have allowed a determination of the charged pion-nucleon coupling constant by a simple extrapolation to the pion pole. A phenomenological analysis of the line-reversed reaction np -> pn and pbarp -> nbarn data is ongoing, to single out the basic dynamical features of the long-range part of the interaction and possibly experimental manifestations of the G-parity rule.

  11. Vertical spatial coherence model for a transient signal forward-scattered from the sea surface

    Science.gov (United States)

    Yoerger, E.J.; McDaniel, S.T.

    1996-01-01

    The treatment of acoustic energy forward scattered from the sea surface, which is modeled as a random communications scatter channel, is the basis for developing an expression for the time-dependent coherence function across a vertical receiving array. The derivation of this model uses linear filter theory applied to the Fresnel-corrected Kirchhoff approximation in obtaining an equation for the covariance function for the forward-scattered problem. The resulting formulation is used to study the dependence of the covariance on experimental and environmental factors. The modeled coherence functions are then formed for various geometrical and environmental parameters and compared to experimental data.

  12. Enhanced incoherent scatter plasma lines

    Directory of Open Access Journals (Sweden)

    H. Nilsson

    Full Text Available Detailed model calculations of auroral secondary and photoelectron distributions for varying conditions have been used to calculate the theoretical enhancement of incoherent scatter plasma lines. These calculations are compared with EISCAT UHF radar measurements of enhanced plasma lines from both the E and F regions, and published EISCAT VHF radar measurements. The agreement between the calculated and observed plasma line enhancements is good. The enhancement from the superthermal distribution can explain even the very strong enhancements observed in the auroral E region during aurora, as previously shown by Kirkwood et al. The model calculations are used to predict the range of conditions when enhanced plasma lines will be seen with the existing high-latitude incoherent scatter radars, including the new EISCAT Svalbard radar. It is found that the detailed structure, i.e. the gradients in the suprathermal distribution, are most important for the plasma line enhancement. The level of superthermal flux affects the enhancement only in the region of low phase energy where the number of thermal electrons is comparable to the number of suprathermal electrons and in the region of high phase energy where the suprathermal fluxes fall to such low levels that their effect becomes small compared to the collision term. To facilitate the use of the predictions for the different radars, the expected signal- to-noise ratios (SNRs for typical plasma line enhancements have been calculated. It is found that the high-frequency radars (Søndre Strømfjord, EISCAT UHF should observe the highest SNR, but only for rather high plasma frequencies. The VHF radars (EISCAT VHF and Svalbard will detect enhanced plasma lines over a wider range of frequencies, but with lower SNR.

  13. Survey of background scattering from materials found in small-angle neutron scattering

    OpenAIRE

    Barker, J. G.; Mildner, D. F. R.

    2015-01-01

    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300?700?K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a 3He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scatter...

  14. Cooperative scattering of scalar waves by optimized configurations of point scatterers

    Science.gov (United States)

    Schäfer, Frank; Eckert, Felix; Wellens, Thomas

    2017-12-01

    We investigate multiple scattering of scalar waves by an ensemble of N resonant point scatterers in three dimensions. For up to N = 21 scatterers, we numerically optimize the positions of the individual scatterers, to maximize the total scattering cross section for an incoming plane wave, on the one hand, and to minimize the decay rate associated to a long-lived scattering resonance, on the other. In both cases, the optimum is achieved by configurations where all scatterers are placed on a line parallel to the direction of the incoming plane wave. The associated maximal scattering cross section increases quadratically with the number of scatterers for large N, whereas the minimal decay rate—which is realized by configurations that are not the same as those that maximize the scattering cross section—decreases exponentially as a function of N. Finally, we also analyze the stability of our optimized configurations with respect to small random displacements of the scatterers. These results demonstrate that optimized configurations of scatterers bear a considerable potential for applications such as quantum memories or mirrors consisting of only a few atoms.

  15. Degree of coherence in curvilinear coordinates and its application to scattering.

    Science.gov (United States)

    Tong, Zhisong

    2012-07-01

    In the traditional treatment of the spectral degree of coherence, the Cartesian coordinate system is deployed to describe the electromagnetic field. In the description of the far field scattered from random media, however, the spherical polar coordinates system is more suitably used due to the field's outgoing spherical form. We hence derive the expression for the spectral degree of coherence in the spherical polar coordinates system. An example of one polychromatic plane wave scattered by a collection of identical particles is given.

  16. Blue Skies, Coffee Creamer, and Rayleigh Scattering

    Science.gov (United States)

    Liebl, Michael

    2010-01-01

    The first physical explanation of Earths blue sky was fashioned in 1871 by Lord Rayleigh. Many discussions of Rayleigh scattering and approaches to studying it both in and out of the classroom are available. Rayleigh scattering accounts for the blue color of the sky and the orange/red color of the Sun near sunset and sunrise, and a number of…

  17. Fluctuations in doubly scattered laser light

    NARCIS (Netherlands)

    Rijswijk, F.C. van; Smith, U.L.

    1975-01-01

    Fluctuations in laser light, doubly scattered by brownian particles, were analysed by measuring the spectral noise power of the photodetector current. Scattering took place at two spatially separated systems of spherical particles. Analytic expressions for the field and intensity correlations are

  18. Critical Magnetic Scattering of Neutrons in Iron

    DEFF Research Database (Denmark)

    Passell, L.; Blinowski, K.; Brun, T.

    1964-01-01

    scattered at small angles in iron and determined the spin correlation range 1∕κ1 and a parameter Λ associated with the lifetime of the fluctuations. Our results confirm the recent observation of Jacrot, Konstantinovic, Parette, and Cribier that the scattering is not elastic even at the Curie temperature. We...

  19. Efficient Fixed-Offset GPR Scattering Analysis

    DEFF Research Database (Denmark)

    Meincke, Peter; Chen, Xianyao

    2004-01-01

    The electromagnetic scattering by buried three-dimensional penetrable objects, as involved in the analysis of ground penetrating radar systems, is calculated using the extended Born approximation. The involved scattering tensor is calculated using fast Fourier transforms (FFT's). We incorporate i...

  20. Inelastic Neutron Scattering from Cerium under Pressure

    DEFF Research Database (Denmark)

    Rainford, B. D.; Buras, B.; Lebech, Bente

    1977-01-01

    Inelastic neutron scattering from Ce metal at 300 K was studied both below and above the first order γ-α phase transition, using a triple axis spectrometer. It was found that (a) there is no indication of any residual magnetic scattering in the collapsed α phase, and (b) the energy width of the p...

  1. Hermite scatterers in an ultraviolet sky

    Science.gov (United States)

    Parker, Kevin J.

    2017-12-01

    The scattering from spherical inhomogeneities has been a major historical topic in acoustics, optics, and electromagnetics and the phenomenon shapes our perception of the world including the blue sky. The long wavelength limit of ;Rayleigh scattering; is characterized by intensity proportional to k4 (or λ-4) where k is the wavenumber and λ is the wavelength. With the advance of nanotechnology, it is possible to produce scatterers that are inhomogeneous with material properties that are functions of radius r, such as concentric shells. We demonstrate that with proper choice of material properties linked to the Hermite polynomials in r, scatterers can have long wavelength scattering behavior of higher powers: k8, k16, and higher. These ;Hermite scatterers; could be useful in providing unique signatures (or colors) to regions where they are present. If suspended in air under white light, the back-scattered spectrum would be shifted from blue towards violet and then ultraviolet as the higher order Hermite scatterers were illuminated.

  2. High-precision positioning of radar scatterers

    NARCIS (Netherlands)

    Dheenathayalan, P.; Small, D.; Schubert, A.; Hanssen, R.F.

    2016-01-01

    Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy

  3. Double pulse Thomson scattering system at RTP

    NARCIS (Netherlands)

    Beurskens, M. N. A.; Barth, C. J.; Chu, C.C.; Donne, A. J. H.; Herranz, J. A.; Cardozo, N. J. L.; van der Meiden, H. J.; Pijper, F.J.

    1997-01-01

    In this article a double pulse multiposition Thomson scattering diagnostic, under construction at RTP, is discussed. Light from a double pulsed ruby laser (pulse separation: 10-800 mu s, max. 2x12.5 J) is scattered by the free electrons of the tokamak plasma and relayed to a Littrow polychromator

  4. Incoherent Thomson scattering as a diagnostic tool

    NARCIS (Netherlands)

    Barth, C. J.

    1998-01-01

    Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wavelength is much smaller than the plasma Debye length, the total scattered power is

  5. Critical Magnetic Scattering of Neutrons in Iron

    DEFF Research Database (Denmark)

    Passell, L.; Blinowski, K.; Brun, T.

    1965-01-01

    Measurements of the angular and energy distributions of 4.28 Å neutrons scattered at small angles from iron at temperatures above the Curie temperature are described. The results are interpreted in terms of Van Hove's theory of critical magnetic scattering and yield information on the range of spin...

  6. Cascaded Bragg scattering in fiber optics.

    Science.gov (United States)

    Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

    2013-01-15

    We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

  7. Inverse acoustic problem of N homogeneous scatterers

    DEFF Research Database (Denmark)

    Berntsen, Svend

    2002-01-01

    The three-dimensional inverse acoustic medium problem of N homogeneous objects with known geometry and location is considered. It is proven that one scattering experiment is sufficient for the unique determination of the complex wavenumbers of the objects. The mapping from the scattered fields...

  8. The Amsterdam-Granada Light Scattering Database

    NARCIS (Netherlands)

    Muñoz, O.; Moreno, F.; Guirado, D.; Dabrowska, D.D.; Volten, H.; Hovenier, J.W.

    2012-01-01

    The Amsterdam Light Scattering Database proved to be a very successful way of promoting the use of the data obtained with the Amsterdam Light Scattering apparatus at optical wavelengths. Many different research groups around the world made use of the experimental data. After the closing down of the

  9. Energy transfer in scattering by rotating potentials

    Indian Academy of Sciences (India)

    Quantum mechanical scattering theory is studied for time-dependent Schrödinger operators, in particular for particles in a rotating potential. Under various assumptions about the decay rate at infinity we show uniform boundedness in time for the kinetic energy of scattering states, existence and completeness of wave ...

  10. Scattering Amplitudes via Algebraic Geometry Methods

    DEFF Research Database (Denmark)

    Søgaard, Mads

    Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized...

  11. Study of surgical treatment on neovascular glaucoma

    Directory of Open Access Journals (Sweden)

    Xiao-Nü Liu

    2014-05-01

    Full Text Available AIM: To compare the effect of two surgical methods on neovascular glaucoma(NVG. METHODS: The clinical date of 46 cases(57 eyeswith NVG underwent surgical treatment were retrospectively analyzed and followed-up. Patients were divided into Ahmed glaucoma valve(AGVimplantation group(group A, 24 cases, 31 eyesand semiconductor diode laser transscleral ciliary body photocoagulation(TSCPCgroup(group B, 22cases, 26 eyesaccording to the surgical approach. The intraocular pressure, visual acuity and postoperative complications were compared before and after operation. RESULTS: The intraocular pressure postoperative in two groups were significantly lower than those preoperative(P P>0.05. The changes of visual acuity postoperative showed no statistical difference between the two groups(P>0.05. The postoperative complications of group A was significantly lower than that in group B, in which the incidence of eye pain, anterior chamber bleeding were significant differences between two groups(P CONCLUSION: AGV implantation treatment and TSCPC for NVG are both valid, but AGV implantation is filtration surgery, and TSCPC isciliary body destructive surgery, and the latter has higher rate of postoperative complications.

  12. Recoil corrections in antikaon-deuteron scattering

    Directory of Open Access Journals (Sweden)

    Mai Maxim

    2016-01-01

    Full Text Available Using the non-relativistic effective field theory approach for K−d scattering, it is demonstrated that a systematic perturbative expansion of the recoil corrections in the parameter ξ = MK/mN is possible in spite of the fact that K−d scattering at low energies is inherently non-perturbative due to the large values of the K̄N scattering lengths. The first order correction to the K−d scattering length due to single insertion of the retardation term in the multiple-scattering series is calculated. The recoil effect turns out to be reasonably small even at the physical value of MK/mN ≃ 0:5.

  13. Rotational superradiant scattering in a vortex flow

    Science.gov (United States)

    Torres, Theo; Patrick, Sam; Coutant, Antonin; Richartz, Maurício; Tedford, Edmund W.; Weinfurtner, Silke

    2017-09-01

    When an incident wave scatters off of an obstacle, it is partially reflected and partially transmitted. In theory, if the obstacle is rotating, waves can be amplified in the process, extracting energy from the scatterer. Here we describe in detail the first laboratory detection of this phenomenon, known as superradiance. We observed that waves propagating on the surface of water can be amplified after being scattered by a draining vortex. The maximum amplification measured was 14% +/- 8%, obtained for 3.70 Hz waves, in a 6.25-cm-deep fluid, consistent with the superradiant scattering caused by rapid rotation. We expect our experimental findings to be relevant to black-hole physics, since shallow water waves scattering on a draining fluid constitute an analogue of a black hole, as well as to hydrodynamics, due to the close relation to over-reflection instabilities.

  14. Gravitomagnetic field and Penrose scattering processes.

    Science.gov (United States)

    Williams, Reva Kay

    2005-06-01

    In this paper we present theoretical model calculations involving Monte Carlo computer simulations of Compton scattering and electron-positron (e-e+) pair production processes in the ergosphere of a supermassive rotating black hole. Particles from an accretion disk surrounding the rotating black hole fall into the ergosphere and are scattered by particles that are confined in equatorial and nonequatorial orbits. The energy-momentum vectors are calculated for the scattered escaping particles. Particles escape with energies of about 3 GeV or greater. Importantly, these model calculations show that the Lense-Thirring effect, that is, the dragging of local inertial frames into rotation, inside the ergosphere, caused by the angular momentum of the rotating black hole, results in a gravitomagnetic force being exerted on the scattered escaping particles. Effects of this force on the Penrose scattered particles are analyzed and discussed.

  15. Scattering cross section for various potential systems

    Directory of Open Access Journals (Sweden)

    Myagmarjav Odsuren

    2017-08-01

    Full Text Available We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the α–α system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the α–α and α–n systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.

  16. Scattering cross section for various potential systems

    Energy Technology Data Exchange (ETDEWEB)

    Odsuren, Myagmarjav; Khuukhenkhuu, Gonchigdorj; Davaa, Suren [Nuclear Research Center, School of Engineering and Applied Sciences, National University of Mongolia, Ulaanbaatar (Mongolia); Kato, Kiyoshi [Nuclear Reaction Data Centre, Faculty of Science, Hokkaido University, Sapporo (Japan)

    2017-08-15

    We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the α–α system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the α–α and α–n systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.

  17. Non-label bioimaging utilizing scattering lights

    Science.gov (United States)

    Watanabe, Tomonobu M.; Ichimura, Taro; Fujita, Hideaki

    2017-04-01

    Optical microscopy is an indispensable tool for medical and life sciences. Especially, the microscopes utilized with scattering light offer a detailed internal observation of living specimens in real time because of their non-labeling and non-invasive capability. We here focus on two kinds of scattering lights, Raman scattering light and second harmonic generation light. Raman scattering light includes the information of all the molecular vibration modes of the molecules, and can be used to distinguish types and/or state of cell. Second harmonic generation light is derived from electric polarity of proteins in the specimen, and enables to detect their structural change. In this conference, we would like to introduce our challenges to extract biological information from those scattering lights.

  18. Improved Gaussian Beam-Scattering Algorithm

    Science.gov (United States)

    Lock, James A.

    1995-01-01

    The localized model of the beam-shape coefficients for Gaussian beam-scattering theory by a spherical particle provides a great simplification in the numerical implementation of the theory. We derive an alternative form for the localized coefficients that is more convenient for computer computations and that provides physical insight into the details of the scattering process. We construct a FORTRAN program for Gaussian beam scattering with the localized model and compare its computer run time on a personal computer with that of a traditional Mie scattering program and with three other published methods for computing Gaussian beam scattering. We show that the analytical form of the beam-shape coefficients makes evident the fact that the excitation rate of morphology-dependent resonances is greatly enhanced for far off-axis incidence of the Gaussian beam.

  19. Radiofrequency encoded angular-resolved light scattering

    DEFF Research Database (Denmark)

    Buckley, Brandon W.; Akbari, Najva; Diebold, Eric D.

    2015-01-01

    The sensitive, specific, and label-free classification of microscopic cells and organisms is one of the outstanding problems in biology. Today, instruments such as the flow cytometer use a combination of light scatter measurements at two distinct angles to infer the size and internal complexity...... of cells at rates of more than 10,000 per second. However, by examining the entire angular light scattering spectrum it is possible to classify cells with higher resolution and specificity. Current approaches to performing these angular spectrum measurements all have significant throughput limitations...... Encoded Angular-resolved Light Scattering (REALS), this technique multiplexes angular light scattering in the radiofrequency domain, such that a single photodetector captures the entire scattering spectrum from a particle over approximately 100 discrete incident angles on a single shot basis. As a proof...

  20. Double hard scattering without double counting

    Science.gov (United States)

    Diehl, Markus; Gaunt, Jonathan R.; Schönwald, Kay

    2017-06-01

    Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

  1. Double hard scattering without double counting

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [VU Univ. Amsterdam (Netherlands). NIKHEF Theory Group; Schoenwald, Kay [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2017-02-15

    Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

  2. Higher moments of scattered light fields by heterodyne analysis

    Science.gov (United States)

    Harris, M.; Paerson, G. N.; Hill, C. A.; Vaughan, J. M.

    1994-10-01

    A simple scattering experiment employing heterodyne detection and operating in Gaussian scattering regime (with large number of illuminated independent scatterers) is shown to yield experimental values of higher-order moments of scattered light intensity distribution in agreement with theoretical predictions. This permits assessment of Gaussian behavior. Laser light scattering from a rotating glass screen is used in the study.

  3. Seismic energy transmission in an intensively scattering environment

    Science.gov (United States)

    Nakamura, Y.

    1977-01-01

    In order to account for some special features of lunar seismograms, namely, the gradual build-up of the signal, the extremely prolonged tail, and the lack of apparent coherence among three orthogonal components of ground motion, a statistical approach is proposed for describing transmission of seismic energy through a medium in which strong scattering takes place. A seismic diffusion theory is presented for a medium with randomly distributed scatterers of a given size distribution. A solution of the resulting diffusion equation for an impulsive energy source gives a curve which fairly closely reproduces the envelope of typical lunar impact seismograms. Since the model is based on constant diffusivity, long-range transmission will require a combination of diffusion and wave propagation treatments for accurate description.

  4. On the analysis of Deep Inelastic Neutron Scattering Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Blostein, J.J.; Dawidowski, J.; Granada, J.R. [Comision Nacional de Energia Atomica and CONICET, Centro Atomico Bariloche and Instituto Balseiro, Bariloche (Argentina)

    2001-03-01

    We analyze the different steps that must be followed for data processing in Deep Inelastic Neutron Scattering Experiments. Firstly we discuss to what extent multiple scattering effects can affect the measured peak shape, concluding the an accurate calculation of these effects must be performed to extract the desired effective temperature from the experimental data. We present a Monte Carlo procedure to perform these corrections. Next, we focus our attention on experiments performed on light nuclei. We examine cases in which the desired information is obtained from the observed peak areas, and we analyze the procedure to obtain an effective temperature from the experimental peaks. As a consequence of the results emerging from those cases we trace the limits of validity of the convolution formalism usually employed, and propose a different treatment of the experimental data for this kind of measurements. (author)

  5. Modern diagnostic and treatment aspects of diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Aleksandr Viktorovich Doga

    2014-10-01

    Full Text Available Diabetic macular oedema (DMO is the leading cause of vision loss and disability in working-age people with diabetes mellitus.This literature review describes pathogenetic mechanisms, concepts, diagnostic techniques and capabilities of novel laser technologies in the treatment of DMO. In recent years, the role of cytokines and growth factors in retinal neurodegeneration has been actively investigated. Modern diagnostic techniques for the treatment of diabetic macular oedema, in addition to conventional techniques, include optical coherence tomography, autofluorescence and microperimetry. These techniques allow the visualization of retinal structures and its functional condition, and they can be used to detect DMO at early stages and to provide the most effective treatment. The evolution of laser technology resulted in the formation of new approaches to DMO treatment. Subthreshold micropulse laser (SML treatment, in conjunction with conventional photocoagulation, has pronounced therapeutic effects. SML shows high selectivity towards retinal pigment epithelium while avoiding neurosensory retina injury. Owing to the chronic nature of DMO and pathogenetic mechanisms recently discovered, further elaboration of the SML technique appears to be a very promising treatment.

  6. Fluocinolone acetonide intravitreal implant for the treatment of diabetic macular edema

    Directory of Open Access Journals (Sweden)

    Messenger WB

    2013-05-01

    Full Text Available Wyatt B Messenger, Robert M Beardsle, Christina J FlaxelCasey Eye Institute, Oregon Health and Science University, Portland, OR, USAAbstract: Diabetic macular edema (DME remains one of the leading causes of moderate to severe vision loss. Although laser photocoagulation was the standard of care for several years, few patients achieved significant improvements in visual acuity. As a result, several pharmacotherapies and surgeries have been investigated. The fluocinolone acetonide devices are one of the latest therapies considered for the treatment of DME. Despite bringing significant improvements in visual acuity, fluocinolone devices are associated with cataract formation, increased intraocular pressure (IOP, and surgery to lower IOP. Due to the risk of complications, fluocinolone acetonide devices should be considered only in cases refractive to first-line therapies. In this review, we evaluate current and emerging therapies for DME, with special emphasis on fluocinolone acetonide intravitreal devices.Keywords: diabetic macular edema, fluocinolone, anti-VEGF, triamcinolone, dexamethasone

  7. Three-dimensional Monte Carlo model of pulsed-laser treatment of cutaneous vascular lesions

    Science.gov (United States)

    Milanič, Matija; Majaron, Boris

    2011-12-01

    We present a three-dimensional Monte Carlo model of optical transport in skin with a novel approach to treatment of side boundaries of the volume of interest. This represents an effective way to overcome the inherent limitations of ``escape'' and ``mirror'' boundary conditions and enables high-resolution modeling of skin inclusions with complex geometries and arbitrary irradiation patterns. The optical model correctly reproduces measured values of diffuse reflectance for normal skin. When coupled with a sophisticated model of thermal transport and tissue coagulation kinetics, it also reproduces realistic values of radiant exposure thresholds for epidermal injury and for photocoagulation of port wine stain blood vessels in various skin phototypes, with or without application of cryogen spray cooling.

  8. [Intravitreal bevacizumab in the treatment of idiopathic juxtafoveal telangiectasis type I].

    Science.gov (United States)

    García-Ben, A; Gómez-Ulla, F; Rodriguez-Cid, M J

    2014-07-01

    We report a case of a 42 year-old male with a macular edema due to idiopathic juxtafoveal retinal telangiectasis type i, treated with 3 sequential injections of intravitreal bevacizumab (1.25 mg in 0.05 ml). Anatomical improvements were observed after one year of follow up. There is currently no general consensus regarding the treatment of unilateral idiopathic juxtafoveal telangiectasis. The therapeutic options are, grid laser photocoagulation, intravitreal triamcinolone, verteporfin photodynamic therapy, or anti-VEGF. Visual acuity and anatomical improvements were observed in this case after intravitreal bevacizumab. Thus, intravitreal bevacizumab seems to be effective to treat macular edema in idiopathic juxtafoveal telangiectasis type i. Copyright © 2011 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  9. Electron scattering in graphene with adsorbed NaCl nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Drabińska, Aneta, E-mail: Aneta.Drabinska@fuw.edu.pl; Kaźmierczak, Piotr; Bożek, Rafał; Karpierz, Ewelina; Wysmołek, Andrzej; Kamińska, Maria [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Wołoś, Agnieszka [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Pasternak, Iwona; Strupiński, Włodek [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Krajewska, Aleksandra [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

    2015-01-07

    In this work, the results of contactless magnetoconductance and Raman spectroscopy measurements performed for a graphene sample after its immersion in NaCl solution were presented. The properties of the immersed sample were compared with those of a non-immersed reference sample. Atomic force microscopy and electron spin resonance experiments confirmed the deposition of NaCl nanoparticles on the graphene surface. A weak localization signal observed using contactless magnetoconductance showed the reduction of the coherence length after NaCl treatment of graphene. Temperature dependence of the coherence length indicated a change from ballistic to diffusive regime in electron transport after NaCl treatment. The main inelastic scattering process was of the electron-electron type but the major reason for the reduction of the coherence length at low temperatures was additional, temperature independent, inelastic scattering. We associate it with spin flip scattering, caused by NaCl nanoparticles present on the graphene surface. Raman spectroscopy showed an increase in the D and D′ bands intensities for graphene after its immersion in NaCl solution. An analysis of the D, D′, and G bands intensities proved that this additional scattering is related to the decoration of vacancies and grain boundaries with NaCl nanoparticles, as well as generation of new on-site defects as a result of the decoration of the graphene surface with NaCl nanoparticles. The observed energy shifts of 2D and G bands indicated that NaCl deposition on the graphene surface did not change carrier concentration, but reduced compressive biaxial strain in the graphene layer.

  10. Investigation of the effect of scattering agent and scattering albedo on modulated light propagation in water.

    Science.gov (United States)

    Mullen, Linda; Alley, Derek; Cochenour, Brandon

    2011-04-01

    A recent paper described experiments completed to study the effect of scattering on the propagation of modulated light in laboratory tank water [Appl. Opt.48, 2607 (2009)APOPAI0003-693510.1364/AO.48.002607]. Those measurements were limited to a specific scattering agent (Maalox antacid) with a fixed scattering albedo (0.95). The purpose of this paper is to study the effects of different scattering agents and scattering albedos on modulated light propagation in water. The results show that the scattering albedo affects the number of attenuation lengths that the modulated optical signal propagates without distortion, while the type of scattering agent affects the degree to which the modulation is distorted with increasing attenuation length. © 2011 Optical Society of America

  11. Exclusive scattering off the deuteron

    Energy Technology Data Exchange (ETDEWEB)

    Amrath, D.

    2007-12-15

    Exclusive processes are a special class of processes giving insight into the inner structure of hadrons. In this thesis we consider two exclusive processes and compute their total cross sections as well as the beam charge and beam polarization asymmetries for different kinematical constraints. These calculations o er the opportunity to get access to the nonperturbative GPDs. Theoretically they can be described with the help of models. The rst process we investigate contains a GPD of the pion, which is basically unknown so far. We include different models and make predictions for observables that could in principle be measured at HERMES at DESY and CLAS at JLab. The second process we consider is electron-deuteron scattering in the kinematical range where the deuteron breaks up into a proton and a neutron. This can be used to investigate the neutron, which cannot be taken as a target due to its lifetime of approximately 15 minutes. For the calculation of the electron-deuteron cross section we implement models for the proton and neutron GPDs. Once there are experimental data available our calculations are ready for comparison. (orig.)

  12. Parity nonconserving asymmetry in neutron-deuteron and proton-deuteron scattering

    Science.gov (United States)

    Kloet, W. M.; Gibson, B. F.; Stephenson, G. J., Jr.; Henley, E. M.

    1983-06-01

    Parity nonconservation in nucleon (N)-deuteron(d) scattering is examined at low energies (<=40 MeV), particularly at 15 MeV. A Faddeev treatment is employed. For the strong N- force a separable interaction, which fits scattering cross sections up to 60-100 MeV, is used; for the weak parity nonconserving NN force, an isoscalar short range term due to ρ and ω exchanges and an isovector pion exchange contribution are included. Comparisons with parity nonconserving experimental asymmetries in NN scattering are made. For the parity nonconserving asymmetry in N-d scattering the contributions of various terms are separated, so that the model dependence of our results can be discussed. It is found that multiple scattering effects are important. The energy dependence of the parity nonconserving asymmetry in N-d scattering is found to differ qualitatively from that in NN scattering. NUCLEAR REACTIONS d(N, N)d, calculated total cross section parity nonconserving asymmetry, E=14-40 MeV.

  13. Propofol and fentanyl sedation for laser treatment of retinopathy of prematurity to avoid intubation.

    Science.gov (United States)

    Piersigilli, Fiammetta; Di Pede, Alessandra; Catena, Gino; Lozzi, Simona; Auriti, Cinzia; Bersani, Iliana; Capolupo, Irma; Lipreri, Anna; Di Ciommo, Vincenzo; Dotta, Andrea; Sgrò, Stefania

    2017-10-03

    Despite the optimization of neonatal assistance, severe retinopathy of prematurity (ROP, stage III-IV) remains a common condition among preterm infants. Laser photocoagulation usually requires general anesthesia and intubation, but extubation can be difficult and these infants often affected by chronic lung disease. We retrospectively evaluated the clinical charts of 13 neonates that were sedated with propofol in association with fentanyl for the laser treatment of ROP. This protocol was introduced in our unit to avoid intubation and minimize side effects of anesthesia and ventilation. Propofol 5% followed by a bolus of fentanyl was administered as sedation during laser therapy to 13 preterm infants, affected by ROP stage III-IV. Propofol was initially infused as a slow bolus of 2-4 mg/kg and then continuously during the entire procedure, at 4 mg/kg/hour, increasing the dosage to 6 mg/kg/hour if sedation was not achieved. A laryngeal mask was placed and patients were ventilated with a flow-inflating resuscitation bag. Thirteen neonates were treated allowing to perform surgery without intubation. Only 4/13 (30.8%) of infants required minimal respiratory support during and/or after surgery. Heart rate after the intervention was higher than that at the beginning while remaining in the range of normal values. Blood pressures before, during and after surgery were similar. No episodes of bradycardia nor hypotension were recorded. Laser treatment was always successful. The good level of anesthesia and analgesia achieved sustains the efficacy of sedation with propofol during laser photocoagulation to avoid intubation and mechanical ventilation during and after the procedure.

  14. Intravitreal bevacizumab (Avastin treatment of diffuse diabetic macular edema in an Indian population

    Directory of Open Access Journals (Sweden)

    Kumar Atul

    2007-01-01

    Full Text Available Background: To report the anatomic and visual acuity response after intravitreal bevacizumab (Avastin in patients with diffuse diabetic macular edema. Design: Prospective, interventional case series study. Materials and Methods: This study included 20 eyes of metabolically stable diabetes mellitus with diffuse diabetic macular edema with a mean age of 59 years who were treated with two intravitreal injections of bevacizumab 1.25 mg in 0.05 ml six weeks apart. Main outcome measures were 1 early treatment diabetic retinopathy study visual acuity, 2 central macular thickness by optical coherence tomography imaging. Each was evaluated at baseline and follow-up visits. Results: All the eyes had received some form of laser photocoagulation before (not less than six months ago, but all of these patients had persistent diffuse macular edema with no improvement in visual acuity. All the patients received two injections of bevacizumab at an interval of six weeks per eye. No adverse events were observed, including endophthalmitis, inflammation and increased intraocular pressure or thromboembolic events in any patient. The mean baseline acuity was 20/494 (log Mar=1.338±0.455 and the mean acuity at three months following the second intravitreal injection was 20/295 (log Mar=1.094±0.254, a difference that was highly significant ( P =0.008. The mean central macular thickness at baseline was 492 µm which decreased to 369 µm ( P =0.001 at the end of six months. Conclusions: Initial treatment results of patients with diffuse diabetic macular edema not responding to previous photocoagulation did not reveal any short-term safety concerns. Intravitreal bevacizumab resulted in a significant decrease in macular thickness and improvement in visual acuity at three months but the effect was somewhat blunted, though still statistically significant at the end of six months.

  15. Light scattering by aggregated red blood cells

    Science.gov (United States)

    Tsinopoulos, Stephanos V.; Sellountos, Euripides J.; Polyzos, Demosthenes

    2002-03-01

    In low flow rates, red blood cells (RBCs) fasten together along their axis of symmetry and form a so-called rouleaux. The scattering of He-Ne laser light by a rouleau consisting of n (2 less-than-or-equal n less-than-or-equal 8) average-sized RBCs is investigated. The interaction problem is treated numerically by means of an advanced axisymmetric boundary element--fast Fourier transform methodology. The scattering problem of one RBC was solved first, and the results showed that the influence of the RBC's membrane on the scattering patterns is negligible. Thus the rouleau is modeled as an axisymmetric, homogeneous, low-contrast dielectric cylinder, on the surface of which appears, owing to aggregated RBCs, a periodic roughness along the direction of symmetry. The direction of the incident laser light is considered to be perpendicular to the scatterer's axis of symmetry. The differential scattering cross sections in both perpendicular and parallel scattering planes and for all the scattering angles are calculated and presented in detail.

  16. The Amsterdam-Granada Light Scattering Database

    Science.gov (United States)

    Muñoz, O.; Moreno, F.; Guirado, D.; Dabrowska, D. D.; Volten, H.; Hovenier, J. W.

    2012-02-01

    The Amsterdam Light Scattering Database proved to be a very successful way of promoting the use of the data obtained with the Amsterdam Light Scattering apparatus at optical wavelengths. Many different research groups around the world made use of the experimental data. After the closing down of the Dutch scattering apparatus, a modernized and improved descendant, the IAA Cosmic Dust Laboratory (CoDuLab), has been constructed at the Instituto de Astrofísica de Andalucía (IAA) in Granada, Spain. The first results of this instrument for water droplets and for two samples of clay particles have been published. We would now like to make these data also available to the community in digital form by introducing a new light scattering database, the Amsterdam-Granada Light Scattering Database (www.iaa.es/scattering). By combining the data from the two instruments in one database we ensure the continued availability of the old data, and we prevent fragmentation of important data over different databases. In this paper we present the Amsterdam-Granada Light Scattering Database.

  17. Autofocus imaging : Image reconstruction based on inverse scattering theory

    NARCIS (Netherlands)

    Behura, J.; Wapenaar, C.P.A.; Snieder, R.

    2014-01-01

    Conventional imaging algorithms assume single scattering and therefore cannot image multiply scattered waves correctly. The multiply scattered events in the data are imaged at incorrect locations resulting in spurious subsurface structures and erroneous interpretation. This drawback of current

  18. Neutron Scattering from 36Ar and 4He Films

    DEFF Research Database (Denmark)

    Carneiro, K.

    1977-01-01

    Scale factors for neutron diffraction and neutron inelastic scattering are presented for common adsorbates, and the feasibility of experiments is discussed together with the information gained by each type of experiment. Diffraction, coherent inelastic scattering, and incoherent scattering are tr...

  19. Scattering resonances in the extreme quantum limit

    Science.gov (United States)

    Hersch, Jesse Shines

    This thesis addresses topics in low energy scattering in quantum mechanics, in particular, resonance phenomena. Hence the title: the phrase ``extreme quantum limit'' refers to the situation when the wavelengths of the particles in the system are larger than every other scale, so that the behavior is far into the quantum regime. A powerful tool in the problems of low energy scattering is the point scatterer model, and will be used extensively throughout the thesis. Therefore, we begin with a thorough introduction to this model in Chapter 2. As a first application of the point scatterer model, we will investigate the phenomenon of the proximity resonance, which is one example of strange quantum behavior appearing at low energy. Proximity resonances will be addressed theoretically in Chapter 3, and experimentally in Chapter 4. Threshold resonances, another type of low energy scattering resonance, are considered in Chapter 5, along with their connection to the Efimov and Thomas effects, and scattering in the presence of an external confining potential. Although the point scatterer model will serve us well in the work presented here, it does have its limitations. These limitations will be removed in Chapter 6, where we describe how to extend the model to include higher partial waves. In Chapter 7, we extend the model one step further, and illustrate how to treat vector wave scattering with the model. Finally, in Chapter 8 we will depart from the topic of low energy scattering and investigate the influence of diffraction on an open quantum mechanical system, again both experimentally and theoretically.

  20. The history of scatter hoarding studies.

    Science.gov (United States)

    Brodin, Anders

    2010-03-27

    In this review, I will present an overview of the development of the field of scatter hoarding studies. Scatter hoarding is a conspicuous behaviour and it has been observed by humans for a long time. Apart from an exceptional experimental study already published in 1720, it started with observational field studies of scatter hoarding birds in the 1940s. Driven by a general interest in birds, several ornithologists made large-scale studies of hoarding behaviour in species such as nutcrackers and boreal titmice. Scatter hoarding birds seem to remember caching locations accurately, and it was shown in the 1960s that successful retrieval is dependent on a specific part of the brain, the hippocampus. The study of scatter hoarding, spatial memory and the hippocampus has since then developed into a study system for evolutionary studies of spatial memory. In 1978, a game theoretical paper started the era of modern studies by establishing that a recovery advantage is necessary for individual hoarders for the evolution of a hoarding strategy. The same year, a combined theoretical and empirical study on scatter hoarding squirrels investigated how caches should be spaced out in order to minimize cache loss, a phenomenon sometimes called optimal cache density theory. Since then, the scatter hoarding paradigm has branched into a number of different fields: (i) theoretical and empirical studies of the evolution of hoarding, (ii) field studies with modern sampling methods, (iii) studies of the precise nature of the caching memory, (iv) a variety of studies of caching memory and its relationship to the hippocampus. Scatter hoarding has also been the subject of studies of (v) coevolution between scatter hoarding animals and the plants that are dispersed by these.

  1. Elastic scattering of surface plasmon polaritons: Modeling and experiment

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Coello, V.

    1998-01-01

    Elastic (in-plane) scattering of surface plasmon polaritons (SPP's) is modeled by considering isotropic pointlike scatterers whose responses to the incident SPP field are phenomenologically related to their effective polarizabilities. Numerical simulations of single, double, and multiple scattering...... are presented for randomly situated scatterers showing the interplay between different orders of scattering and localization phenomena. Correlation between the scattering regimes and spatial Fourier spectra of the corresponding SPP intensity distributions is considered. Various optical microcomponents (e...

  2. Scattering loss of antiresonant reflecting optical waveguides

    OpenAIRE

    Baba, Toshihiko; Kokubun, Yasuo

    1991-01-01

    Scattering loss of two-dimensional ARROW-type waveguides, i.e., antiresonant reflecting optical waveguide (ARROW) and ARROW-B, is analyzed by the first-order perturbation theory. Calculated results are compared with those of conventional three-layer waveguides. Optimum design for the reduction of scattering loss of these ARROW-type waveguides is discussed. It was found that the scattering loss of ARROW-type waveguides is no larger than that of a conventional waveguide having a relative refrac...

  3. Simulation of low-energy ion scattering

    Science.gov (United States)

    Langelaar, M. H.; Breeman, M.; Mijiritskii, A. V.; Boerma, D. O.

    A new simulation program `MATCH' has been developed for a detailed analysis of low-energy ion scattering (LEIS) and recoiling data. Instead of performing the full calculation of the three-dimensional trajectories through the sample from the ion source towards the detector, incoming trajectories as well as reversed-time outgoing trajectories are calculated, separately. Finally, these trajectories are matched to obtain the yield. The program has been tested for spectra and azimuthal scans of scattering and recoiling events of various sample species in different scattering geometries.

  4. Modeling Electromagnetic Scattering From Complex Inhomogeneous Objects

    Science.gov (United States)

    Deshpande, Manohar; Reddy, C. J.

    2011-01-01

    This software innovation is designed to develop a mathematical formulation to estimate the electromagnetic scattering characteristics of complex, inhomogeneous objects using the finite-element-method (FEM) and method-of-moments (MoM) concepts, as well as to develop a FORTRAN code called FEMOM3DS (Finite Element Method and Method of Moments for 3-Dimensional Scattering), which will implement the steps that are described in the mathematical formulation. Very complex objects can be easily modeled, and the operator of the code is not required to know the details of electromagnetic theory to study electromagnetic scattering.

  5. Quantum optics in multiple scattering random media

    DEFF Research Database (Denmark)

    Lodahl, Peter

    Quantum Optics in Multiple Scattering Random Media Peter Lodahl Research Center COM, Technical University of Denmark, Dk-2800 Lyngby, Denmark. Coherent transport of light in a disordered random medium has attracted enormous attention both from a fundamental and application point of view. Coherent...... quantum optics in multiple scattering media and novel fundamental phenomena have been predicted when examining quantum fluctuations instead of merely the intensity of the light [1]. Here I will present the first experimental study of the propagation of quantum noise through an elastic, multiple scattering...

  6. Techniques in high pressure neutron scattering

    CERN Document Server

    Klotz, Stefan

    2013-01-01

    Drawing on the author's practical work from the last 20 years, Techniques in High Pressure Neutron Scattering is one of the first books to gather recent methods that allow neutron scattering well beyond 10 GPa. The author shows how neutron scattering has to be adapted to the pressure range and type of measurement.Suitable for both newcomers and experienced high pressure scientists and engineers, the book describes various solutions spanning two to three orders of magnitude in pressure that have emerged in the past three decades. Many engineering concepts are illustrated through examples of rea

  7. Anisotropic resonant scattering from polymer photonic crystals.

    Science.gov (United States)

    Haines, Andrew I; Finlayson, Chris E; Snoswell, David R E; Spahn, Peter; Hellmann, G Peter; Baumberg, Jeremy J

    2012-11-20

    Hyperspectral goniometry reveals anisotropic scattering which dominates the visual appearance of self-assembled polymer opals. The technique allows reconstruction of the reciprocal-space of nanostructures, and indicates that chain defects formed during shear-ordering are responsible for the anisotropy in these samples. Enhanced scattering with improving order is shown to arise from increased effective refractive index contrast, while broadband background scatter is suppressed by absorptive dopants. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Neutron scattering studies of modulated magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Aagaard Soerensen, Steen

    1999-08-01

    This report describes investigations of the magnetic systems DyFe{sub 4}Al{sub 8} and MnSi by neutron scattering and in the former case also by X-ray magnetic resonant scattering. The report is divided into three parts: An introduction to the technique of neutron scattering with special emphasis on the relation between the scattering cross section and the correlations between the scattering entities of the sample. The theoretical framework of neutron scattering experiments using polarized beam technique is outlined. The second part describes neutron and X-ray scattering investigation of the magnetic structures of DyFe{sub 4}Al{sub 8}. The Fe sublattice of the compound order at 180 K in a cycloidal structure in the basal plane of the bct crystal structure. At 25 K the ordering of the Dy sublattice shows up. By the element specific technique of X-ray resonant magnetic scattering, the basal plane cycloidal structure was also found for the Dy sublattice. The work also includes neutron scattering studies of DyFe{sub 4}Al{sub 8} in magnetic fields up to 5 T applied along a <110> direction. The modulated structure at the Dy sublattice is quenched by a field lower than 1 T, whereas modulation is present at the Fe sublattice even when the 5 T field is applied. In the third part of the report, results from three small angle neutron experiments on MnSi are presented. At ambient pressure, a MnSi is known to form a helical spin density wave at temperature below 29 K. The application of 4.5 kbar pressure intended as hydrostatic decreased the Neel temperature to 25 K and changed the orientation of the modulation vector. To understand this reorientation within the current theoretical framework, anisotropic deformation of the sample crystal must be present. The development of magnetic critical scattering with an isotropic distribution of intensity has been studied at a level of detail higher than that of work found in the literature. Finally the potential of a novel polarization

  9. Biological cell classification by multiangle light scattering

    Science.gov (United States)

    Salzman, G.C.; Crowell, J.M.; Mullaney, P.F.

    1975-06-03

    The specification is directed to an apparatus and method for detecting light scattering from a biological cell. Light, preferably from a coherent source of radiation, intercepts an individual biological cell in a stream of cells passing through the beam. Light scattered from the cell is detected at a selected number of angles between 0 and 90/sup 0/ to the longitudinal axis of the beam with a circular array of light responsive elements which produce signals representative of the intensity of light incident thereon. Signals from the elements are processed to determine the light-scattering pattern of the cell and therefrom its identity.

  10. Scattering theory of molecules, atoms and nuclei

    CERN Document Server

    Canto, L Felipe

    2012-01-01

    The aim of the book is to give a coherent and comprehensive account of quantum scattering theory with applications to atomic, molecular and nuclear systems. The motivation for this is to supply the necessary theoretical tools to calculate scattering observables of these many-body systems. Concepts which are seemingly different for atomic/molecular scattering from those of nuclear systems, are shown to be the same once physical units such as energy and length are diligently clarified. Many-body resonances excited in nuclear systems are the same as those in atomic systems and come under the name

  11. Scalar scattering via conformal higher spin exchange

    Energy Technology Data Exchange (ETDEWEB)

    Joung, Euihun [School of Physics and Astronomy,Seoul National University, Seoul 151-747 (Korea, Republic of); Gauge, Gravity & Strings, Center for Theoretical Physics of the Universe,Institute for Basic Sciences, Daejeon 34047 (Korea, Republic of); Nakach, Simon; Tseytlin, Arkady A. [Theoretical physics group, Blackett Laboratory,Imperial College London, SW7 2AZ (United Kingdom)

    2016-02-18

    Theories containing infinite number of higher spin fields require a particular definition of summation over spins consistent with their underlying symmetries. We consider a model of massless scalars interacting (via bilinear conserved currents) with conformal higher spin fields in flat space. We compute the tree-level four-scalar scattering amplitude using a natural prescription for summation over an infinite set of conformal higher spin exchanges and find that it vanishes. Independently, we show that the vanishing of the scalar scattering amplitude is, in fact, implied by the global conformal higher spin symmetry of this model. We also discuss one-loop corrections to the four-scalar scattering amplitude.

  12. Carrier scattering in metals and semiconductors

    CERN Document Server

    Gantmakher, VF

    1987-01-01

    The transport properties of solids, as well as the many optical phenomena in them are determined by the scattering of current carriers. ``Carrier Scattering in Metals and Semiconductors'' elucidates the state of the art in the research on the scattering mechanisms for current carriers in metals and semiconductors and describes experiments in which these mechanisms are most dramatically manifested.The selection and organization of the material is in a form to prepare the reader to reason independently and to deal just as independently with available theoretical results and experimental

  13. Scattering in remote sensing in the visible and microwave spectral range and in traffic control

    Directory of Open Access Journals (Sweden)

    U. Böttger

    2003-01-01

    Full Text Available The treatment of scattering processes in remote sensing for interpretation of satellite data is demonstrated in the visible and microwave spectral range comparing the two spectral ranges. Analogies and distinctions in the treatment of the scattering processes are shown. Based on this cognition an approach for traffic simulation is outlined. Simulating the traffic of a part of a city, a whole city or a larger area in an acceptable time is one of the tasks in recent traffic research. One possible approach is the areal treatment of the road network. That means that single streets are not resolved but are introduced into simulations only by parameters that correspond to a specific traffic area resistance. The aim of this work is to outline such a possibility using experiences obtained from the theory of radiative transport to simulate scattering processes and applying them to the very complex system of traffic simulation.

  14. Ion Scattering in a Self-Consistent Cylindrical Plasma Sheath

    National Research Council Canada - National Science Library

    Figueroa, Shana S; Cooke, D. L; Gatsonis, Nikos A

    2005-01-01

    .... Results indicate that higher plasma shielding limits the range of impact parameters that experience significant scattering, and that attracted particles entering tangent to the sheath experience increased scattering...

  15. Core-shell colloidal particles with dynamically tunable scattering properties.

    Science.gov (United States)

    Meng, Guangnan; Manoharan, Vinothan N; Perro, Adeline

    2017-09-27

    We design polystyrene-poly(N'-isopropylacrylamide-co-acrylic acid) core-shell particles that exhibit dynamically tunable scattering. We show that under normal solvent conditions the shell is nearly index-matched to pure water, and the particle scattering is dominated by Rayleigh scattering from the core. As the temperature or salt concentration increases, both the scattering cross-section and the forward scattering increase, characteristic of Mie scatterers. The magnitude of the change in the scattering cross-section and scattering anisotropy can be controlled through the solvent conditions and the size of the core. Such particles may find use as optical switches or optical filters with tunable opacity.

  16. Equilibrium limit of thermal conduction and boundary scattering in nanostructures.

    Science.gov (United States)

    Haskins, Justin B; Kınacı, Alper; Sevik, Cem; Çağın, Tahir

    2014-06-28

    Determining the lattice thermal conductivity (κ) of nanostructures is especially challenging in that, aside from the phonon-phonon scattering present in large systems, the scattering of phonons from the system boundary greatly influences heat transport, particularly when system length (L) is less than the average phonon mean free path (MFP). One possible route to modeling κ in these systems is through molecular dynamics (MD) simulations, inherently including both phonon-phonon and phonon-boundary scattering effects in the classical limit. Here, we compare current MD methods for computing κ in nanostructures with both L ⩽ MFP and L ≫ MFP, referred to as mean free path constrained (cMFP) and unconstrained (uMFP), respectively. Using a (10,0) CNT (carbon nanotube) as a benchmark case, we find that while the uMFP limit of κ is well-defined through the use of equilibrium MD and the time-correlation formalism, the standard equilibrium procedure for κ is not appropriate for the treatment of the cMFP limit because of the large influence of boundary scattering. To address this issue, we define an appropriate equilibrium procedure for cMFP systems that, through comparison to high-fidelity non-equilibrium methods, is shown to be the low thermal gradient limit to non-equilibrium results. Further, as a means of predicting κ in systems having L ≫ MFP from cMFP results, we employ an extrapolation procedure based on the phenomenological, boundary scattering inclusive expression of Callaway [Phys. Rev. 113, 1046 (1959)]. Using κ from systems with L ⩽ 3 μm in the extrapolation, we find that the equilibrium uMFP κ of a (10,0) CNT can be predicted within 5%. The equilibrium procedure is then applied to a variety of carbon-based nanostructures, such as graphene flakes (GF), graphene nanoribbons (GNRs), CNTs, and icosahedral fullerenes, to determine the influence of size and environment (suspended versus supported) on κ. Concerning the GF and GNR systems, we find that

  17. Multiple-scattering theory. New developments and applications

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Arthur

    2007-12-04

    Multiple-scattering theory (MST) is a very efficient technique for calculating the electronic properties of an assembly of atoms. It provides explicitly the Green function, which can be used in many applications such as magnetism, transport and spectroscopy. This work gives an overview on recent developments of multiple-scattering theory. One of the important innovations is the multiple scattering implementation of the self-interaction correction approach, which enables realistic electronic structure calculations of systems with localized electrons. Combined with the coherent potential approximation (CPA), this method can be applied for studying the electronic structure of alloys and as well as pseudo-alloys representing charge and spin disorder. This formalism is extended to finite temperatures which allows to investigate phase transitions and thermal fluctuations in correlated materials. Another novel development is the implementation of the self-consistent non-local CPA approach, which takes into account charge correlations around the CPA average and chemical short range order. This formalism is generalized to the relativistic treatment of magnetically ordered systems. Furthermore, several improvements are implemented to optimize the computational performance and to increase the accuracy of the KKR Green function method. The versatility of the approach is illustrated in numerous applications. (orig.)

  18. Study of thermal scattering for organic tissues through molecular dynamics

    Directory of Open Access Journals (Sweden)

    Ramos Ricardo

    2017-01-01

    Full Text Available Boron Neutron Capture Therapy (BNCT is an experimental therapy for tumors which is based on the nuclear reaction that occurs when 10B is irradiated with thermal neutrons. Calculations for BNCT with Monte Carlo N-Particle (MCNP take into account the thermal scattering treatment for hydrogen bound in bulk water for any organic tissue. However, in these tissues, hydrogen is also present in macromolecules (protein, lipids, etc. and in confined water. Thermal scattering cross section for hydrogen in an organic tissue can be determined by calculating the scattering law S(α,β. This function can be obtained with the nuclear data processing system NJOY from the vibrational frequency spectrum of an atom in a molecular system. We performed calculations of the frequency spectrum from molecular dynamics simulations using the program GROMACS. Systems composed of a peptide in a water box were considered, with different proportions of water molecules. All-atom potentials for modeling this molecules were used in order to represent the internal vibrational normal modes for the atoms of hydrogen. The results showed several internal normal modes that in the case of hydrogen bound in bulk water do not appear.

  19. Study of thermal scattering for organic tissues through molecular dynamics

    Science.gov (United States)

    Ramos, Ricardo; Cantargi, Florencia; Marquez Damian, Jose Ignacio; Gonçalves-Carralves, Manuel Sztejnberg

    2017-09-01

    Boron Neutron Capture Therapy (BNCT) is an experimental therapy for tumors which is based on the nuclear reaction that occurs when 10B is irradiated with thermal neutrons. Calculations for BNCT with Monte Carlo N-Particle (MCNP) take into account the thermal scattering treatment for hydrogen bound in bulk water for any organic tissue. However, in these tissues, hydrogen is also present in macromolecules (protein, lipids, etc.) and in confined water. Thermal scattering cross section for hydrogen in an organic tissue can be determined by calculating the scattering law S(α,β). This function can be obtained with the nuclear data processing system NJOY from the vibrational frequency spectrum of an atom in a molecular system. We performed calculations of the frequency spectrum from molecular dynamics simulations using the program GROMACS. Systems composed of a peptide in a water box were considered, with different proportions of water molecules. All-atom potentials for modeling this molecules were used in order to represent the internal vibrational normal modes for the atoms of hydrogen. The results showed several internal normal modes that in the case of hydrogen bound in bulk water do not appear.

  20. Light Scattering Tools for Cosmic Dust Modeling

    Science.gov (United States)

    Il'in, V. B.; Voshchinnikov, N. V.; Farafonov, V. G.; Henning, Th.; Perelman, A. Ya.

    Because cosmic dust grains vary significantly in both morphology and chemical composition, it is necessary to develop different light scattering tools to analyze their scattering properties and to reconcile these properties with observations. We present a set of recently developed tools which includes a database of optical constants of materials of astronomical interest, exact and approximate methods and numerical codes using various models of a non-spherical inhomogeneous scatterer, a database of optical properties of non-spherical particles, a new approach to find a solution of ill-posed inverse problems in optics, and an original polarized radiation-transfer code applicable to 3D media populated by aligned non-spherical scatterers.

  1. Electron scattering sum rules in polarized nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Lipparini, E.; Stringari, S.

    1989-07-01

    Sum rules for the inelastic scattering of polarized electrons frompolarized nuclei are derived and discussed. The role of the nucleon formfactors is investigated with special emphasis to the case of deuteron and/sup 3/He.

  2. Scattered Radiation Emission Imaging: Principles and Applications

    Directory of Open Access Journals (Sweden)

    M. K. Nguyen

    2011-01-01

    Full Text Available Imaging processes built on the Compton scattering effect have been under continuing investigation since it was first suggested in the 50s. However, despite many innovative contributions, there are still formidable theoretical and technical challenges to overcome. In this paper, we review the state-of-the-art principles of the so-called scattered radiation emission imaging. Basically, it consists of using the cleverly collected scattered radiation from a radiating object to reconstruct its inner structure. Image formation is based on the mathematical concept of compounded conical projection. It entails a Radon transform defined on circular cone surfaces in order to express the scattered radiation flux density on a detecting pixel. We discuss in particular invertible cases of such conical Radon transforms which form a mathematical basis for image reconstruction methods. Numerical simulations performed in two and three space dimensions speak in favor of the viability of this imaging principle and its potential applications in various fields.

  3. Metallic Colloid Wavelength-Ratiometric Scattering Sensors

    Science.gov (United States)

    Roll, David; Malicka, Joanna; Gryczynski, Ignacy; Gryczynski, Zygmunt

    2009-01-01

    Gold and silver colloids display strong colors as a result of electron oscillations induced by incident light, which are referred to as the plasmon absorption. This absorption is dependent on colloid–colloid proximity, which has been the basis of absorption assays using colloids. We now describe a new approach to optical sensing using the light scattering properties of colloids. Colloid aggregation was induced by avidin–biotin interactions, which shifted the plasmon absorption to longer wavelengths. We found the spectral shift results in changes in the scattering at different incident wavelengths. By measuring the ratio of scattered intensities at two incident wavelengths, this measurement was made independent of the total colloid concentration. The high scattering efficiency of the colloids resulted in intensities equivalent to fluorescence when normalized by the optical density of the fluorophore and colloid. This approach can be used in a wide variety of assay formats, including those commonly used with fluorescence detection. PMID:14570195

  4. Multiple scattering of electromagnetic waves by rain

    Science.gov (United States)

    Tsolakis, A.; Stutzman, W. L.

    1982-01-01

    As the operating frequencies of communications systems move higher into the millimeter wave region, the effects of multiple scattering in precipitation media become more significant. In this paper, general formulations are presented for single, first-order multiple, and complete multiple scattering. Included specifically are distributions of particle size, shape, and orientation angle, as well as variation in the medium density along the direction of wave propagation. Calculations are performed for rain. It is shown that the effects of higher-order scattering are not noticeable in either attenuation or channel isolation on a dual-polarized system until frequencies of about 30 GHz are reached. The complete multiple-scattering formulation presented gives accurate results at high millimeter wave frequencies as well as including realistic medium parameter distributions. Furthermore, it is numerically efficient.

  5. Conformal bootstrap, universality and gravitational scattering

    Directory of Open Access Journals (Sweden)

    Steven Jackson

    2015-12-01

    Full Text Available We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large c and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles between two heavy states (BTZ black holes. We find that the operator algebra in this regime is (i universal and identical to that of Liouville CFT, and (ii takes the form of an exchange algebra, specified by an R-matrix that exactly matches the scattering amplitude of 2+1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.

  6. Neutron Brillouin scattering in dense fluids

    Energy Technology Data Exchange (ETDEWEB)

    Verkerk, P. [Technische Univ. Delft (Netherlands); FINGO Collaboration

    1997-04-01

    Thermal neutron scattering is a typical microscopic probe for investigating dynamics and structure in condensed matter. In contrast, light (Brillouin) scattering with its three orders of magnitude larger wavelength is a typical macroscopic probe. In a series of experiments using the improved small-angle facility of IN5 a significant step forward is made towards reducing the gap between the two. For the first time the transition from the conventional single line in the neutron spectrum scattered by a fluid to the Rayleigh-Brillouin triplet known from light-scattering experiments is clearly and unambiguously observed in the raw neutron data without applying any corrections. Results of these experiments are presented. (author).

  7. Advanced optical imaging with scattering lenses

    NARCIS (Netherlands)

    Yilmaz, H.

    2015-01-01

    This thesis describes new advanced optical methods to control light propagation through disordered nanophotonic materials for focusing and high‐resolution imaging applications. A combination of light scattering, wavefront control, and our new image processing algorithms enable using random

  8. Ultrasonic trap for light scattering measurement

    Science.gov (United States)

    Barton, Petr; Pavlu, Jiri

    2017-04-01

    Light scattering is complex phenomenon occurring widely in space environments, including the dense dusty clouds, nebulas or even the upper atmosphere of the Earth. However, when the size of the dust (or of other scattering center) is close to the incident light wavelength, theoretical determination is difficult. In such case, Mie theory is to be used but there is a lack of the material constants for most space-related materials. For experimental measurement of light scattering, we designed unique apparatus, based on ultrasonic trap. Using acoustic levitation we are able to capture the dust grain in midair, irradiate it with laser, and observe scattering directly with goniometer-mounted photodiode. Advantage of this approach is ability to measure directly in the air (thus, no need for the carrier medium) and possibility to study non-spherical particles. Since the trap development is nearly finished and initial experiments are carried out, the paper presents first tests on water droplets.

  9. High Efficiency Low Scatter Echelle Grating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high efficiency low scatter echelle grating will be developed using a novel technique of multiple diamond shaving cuts. The grating will have mirror surfaces on...

  10. Do Cloaked Objects Really Scatter Less?

    Directory of Open Access Journals (Sweden)

    Francesco Monticone

    2013-10-01

    Full Text Available We discuss the global scattering response of invisibility cloaks over the entire electromagnetic spectrum, from static to very high frequencies. Based on linearity, causality, and energy conservation, we show that the total extinction and scattering, integrated over all wavelengths, of any linear, passive, causal, and nondiamagnetic cloak, necessarily increase compared to the uncloaked case. In light of this general principle, we provide a quantitative measure to compare the global performance of different cloaking techniques and we discuss solutions to minimize the global scattering signature of an object using thin, superconducting shells. Our results provide important physical insights on how invisibility cloaks operate and affect the global scattering of an object, suggesting ways to defeat countermeasures aimed at detecting cloaked objects using short impinging pulses.

  11. Imaging partons in exclusive scattering processes

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus

    2012-06-15

    The spatial distribution of partons in the proton can be probed in suitable exclusive scattering processes. I report on recent performance estimates for parton imaging at a proposed Electron-Ion Collider.

  12. Cloaking through cancellation of diffusive wave scattering

    KAUST Repository

    Farhat, Mohamed

    2016-08-10

    A new cloaking mechanism, which makes enclosed objects invisible to diffusive photon density waves, is proposed. First, diffusive scattering from a basic core-shell geometry, which represents the cloaked structure, is studied. The conditions of scattering cancellation in a quasi-static scattering regime are derived. These allow for tailoring the diffusivity constant of the shell enclosing the object so that the fields scattered from the shell and the object cancel each other. This means that the photon flow outside the cloak behaves as if the cloaked object were not present. Diffusive light invisibility may have potential applications in hiding hot spots in infrared thermography or tissue imaging. © 2016 The Author(s) Published by the Royal Society. All rights reserved.

  13. Zero energy scattering calculation in Euclidean space

    Energy Technology Data Exchange (ETDEWEB)

    Carbonell, J. [Institut de Physique Nucléaire, Université Paris-Sud, IN2P3-CNRS, 91406 Orsay Cedex (France); Karmanov, V.A., E-mail: karmanov@sci.lebedev.ru [Lebedev Physical Institute, Leninsky Prospekt 53, 119991 Moscow (Russian Federation)

    2016-03-10

    We show that the Bethe–Salpeter equation for the scattering amplitude in the limit of zero incident energy can be transformed into a purely Euclidean form, as it is the case for the bound states. The decoupling between Euclidean and Minkowski amplitudes is only possible for zero energy scattering observables and allows determining the scattering length from the Euclidean Bethe–Salpeter amplitude. Such a possibility strongly simplifies the numerical solution of the Bethe–Salpeter equation and suggests an alternative way to compute the scattering length in Lattice Euclidean calculations without using the Luscher formalism. The derivations contained in this work were performed for scalar particles and one-boson exchange kernel. They can be generalized to the fermion case and more involved interactions.

  14. The inverse scattering problem for transmission lines

    Science.gov (United States)

    Kay, I.

    1972-01-01

    A number of exact and approximate methods for solving the inverse scattering problem for transmission lines are reviewed. In particular, the application to transmission lines of Marcenko's version of the Gelfand-Levitan exact method for the quantum mechanical problem is compared with a more direct approach based on a different version of the Gelfand-Levitan method. In addition, some aspects of the lack of uniqueness of solutions are discussed, and some open questions related to the inverse scattering problem are suggested.

  15. Resonances in pi-K scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, David J. [Old Dominion University, Norfolk, VA

    2014-06-23

    We have obtained clear signals of resonances in coupled-channel pi K - eta K scattering. Using distillation and a large basis of operators we are able to extract a precise spectrum of energy levels using the variational method. These energies are analysed using inelastic extensions of the Luescher method to obtain scattering amplitudes that clearly describe S, P and D wave resonances, corresponding to the physical K_0^*(1430), the K^*(892) and the K_2^*(1430).

  16. Metric entropy in linear inverse scattering

    Directory of Open Access Journals (Sweden)

    M. A. Maisto

    2016-09-01

    Full Text Available The role of multiple views and/or multiple frequencies on the achievable performance in linear inverse scattering problems is addressed. To this end, the impact of views and frequencies on the Kolmogorov entropy measure is studied. This way the metric information that can be conveyed back from data to the unknown can be estimated. For the sake of simplicity, the study deals with strip scatterers and the cases of discrete angles of incidence and/or frequencies.

  17. Inverse Scattering in a Multipath Environment

    Directory of Open Access Journals (Sweden)

    A. Cuccaro

    2016-09-01

    Full Text Available In this contribution an inverse scattering problem is ad- dressed in a multipath environment. In particular, multipath is created by known ”extra” point-like scatterers (passive elements expressely deployed between the scene under in- vestigation and the source/measurement domains. Through a back-projection imaging scheme, the role of the passive elements on the achievable performance is shown and com- pared to the free-space case.

  18. Inelastic electron-vortex-beam scattering

    OpenAIRE

    Boxem, Van, Ruben; Partoens, Bart; Verbeeck, Jo

    2015-01-01

    Abstract: Recent theoretical and experimental developments in the field of electron-vortex-beam physics have raised questions about what exactly this novelty in the field of electron microscopy (and other fields, such as particle physics) really provides. An important part of the answer to these questions lies in scattering theory. The present investigation explores various aspects of inelastic quantum scattering theory for cylindrically symmetric beams with orbital angular momentum. The mode...

  19. Electrocrystallisation studied in situ by optical scattering

    Science.gov (United States)

    Rönnow, R.; Isidorsson, J.

    1996-12-01

    Optical scattering was measured in situ on an electrochromic tin oxide film during coulometric titration in an electrolyte of 1 M LiClO 4 in propylene carbonate. The normalised scattering increased at the critical point where electrocrystallisation started, according to optical and electrochemical results. A lower potential limit of 1.2V vs Li was established for tin oxide in electrochromic applications. Electrocrystallisation takes place below this limit.

  20. Inelastic critical scattering of neutrons from terbium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O.W.; Marshall, W.

    1967-01-01

    We have measured the inelasticity of the critical neutron scattering in Tb above the Néel temperature. The results show that dynamical slowing down of fluctuations does occur at a second order phase transition.......We have measured the inelasticity of the critical neutron scattering in Tb above the Néel temperature. The results show that dynamical slowing down of fluctuations does occur at a second order phase transition....

  1. A Scatter Storage Scheme for Dictionary Lookups

    Directory of Open Access Journals (Sweden)

    D. M. Murray

    1970-09-01

    Full Text Available Scatter storage schemes are examined with respect to their applicability to dictionary lookup procedures. Of particular interest are virtual scatter methods which combine the advantages of rapid search speed and reasonable storage requirements. The theoretical aspects of computing hash addresses are developed, and several algorithms are evaluated. Finally, experiments with an actual text lookup process are described, and a possible library application is discussed.

  2. Universal chaotic scattering on quantum graphs.

    Science.gov (United States)

    Pluhař, Z; Weidenmüller, H A

    2013-01-18

    We calculate the S-matrix correlation function for chaotic scattering on quantum graphs and show that it agrees with that of random-matrix theory. We also calculate all higher S-matrix correlation functions in the Ericson regime. These, too, agree with random-matrix theory results as far as the latter are known. We conjecture that our results give a universal description of chaotic scattering.

  3. Compton scatter correction for planner scintigraphic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Vaan Steelandt, E.; Dobbeleir, A.; Vanregemorter, J. [Algemeen Ziekenhuis Middelheim, Antwerp (Belgium). Dept. of Nuclear Medicine and Radiotherapy

    1995-12-01

    A major problem in nuclear medicine is the image degradation due to Compton scatter in the patient. Photons emitted by the radioactive tracer scatter in collision with electrons of the surrounding tissue. Due to the resulting loss of energy and change in direction, the scattered photons induce an object dependant background on the images. This results in a degradation of the contrast of warm and cold lesions. Although theoretically interesting, most of the techniques proposed in literature like the use of symmetrical photopeaks can not be implemented on the commonly used gamma camera due to the energy/linearity/sensitivity corrections applied in the detector. A method for a single energy isotope based on existing methods with adjustments towards daily practice and clinical situations is proposed. It is assumed that the scatter image, recorded from photons collected within a scatter window adjacent to the photo peak, is a reasonable close approximation of the true scatter component of the image reconstructed from the photo peak window. A fraction `k` of the image using the scatter window is subtracted from the image recorded in the photo peak window to produce the compensated image. The principal matter of the method is the right value for the factor `k`, which is determined in a mathematical way and confirmed by experiments. To determine `k`, different kinds of scatter media are used and are positioned in different ways in order to simulate a clinical situation. For a secondary energy window from 100 to 124 keV below a photo peak window from 126 to 154 keV, a value of 0.7 is found. This value has been verified using both an antropomorph thyroid phantom and the Rollo contrast phantom.

  4. American Conference on Neutron Scattering 2014

    Energy Technology Data Exchange (ETDEWEB)

    Dillen, J. Ardie [Materials Research Society, Warrendale, PA (United States)

    2014-12-31

    Scientists from the around the world converged in Knoxville, TN to have share ideas, present technical information and contribute to the advancement of neutron scattering. Featuring over 400 oral/poster presentations, ACNS 2014 offered a strong program of plenary, invited and contributed talks and poster sessions covering topics in soft condensed matter, hard condensed matter, biology, chemistry, energy and engineering applications in neutron physics – confirming the great diversity of science that is enabled by neutron scattering.

  5. Scatter Matters: Regularities and Implications for the Scatter of Healthcare Information on the Web

    OpenAIRE

    Bhavnani, Suresh K.; Peck, Frederick A.

    2010-01-01

    Despite the development of huge healthcare Web sites and powerful search engines, many searchers end their searches prematurely with incomplete information. Recent studies suggest that users often retrieve incomplete information because of the complex scatter of relevant facts about a topic across Web pages. However, little is understood about regularities underlying such information scatter. To probe regularities within the scatter of facts across Web pages, this article presents the results...

  6. Bistatic Forward Scattering Radar Detection and Imaging

    Directory of Open Access Journals (Sweden)

    Hu Cheng

    2016-06-01

    Full Text Available Forward Scattering Radar (FSR is a special type of bistatic radar that can implement image detection, imaging, and identification using the forward scattering signals provided by the moving targets that cross the baseline between the transmitter and receiver. Because the forward scattering effect has a vital significance in increasing the targets’ Radar Cross Section (RCS, FSR is quite advantageous for use in counter stealth detection. This paper first introduces the front line technology used in forward scattering RCS, FSR detection, and Shadow Inverse Synthetic Aperture Radar (SISAR imaging and key problems such as the statistical characteristics of forward scattering clutter, accurate parameter estimation, and multitarget discrimination are then analyzed. Subsequently, the current research progress in FSR detection and SISAR imaging are described in detail, including the theories and experiments. In addition, with reference to the BeiDou navigation satellite, the results of forward scattering experiments in civil aircraft detection are shown. Finally, this paper considers future developments in FSR target detection and imaging and presents a new, promising technique for stealth target detection.

  7. Universality of low-energy Rashba scattering

    Science.gov (United States)

    Hutchinson, Joel; Maciejko, Joseph

    2017-09-01

    We investigate the scattering of a quantum particle with a two-dimensional (2D) Rashba spin-orbit coupled dispersion off of circularly symmetric potentials. As the energy of the particle approaches the bottom of the lowest spin-split band, i.e., the van Hove singularity, earlier work has shown that scattering off of an infinite circular barrier exhibits a number of features unusual from the point of view of conventional 2D scattering theory: the low-energy S matrix is independent of the range of the potential, all partial waves contribute equally, the differential cross section becomes increasingly anisotropic and 1D-like, and the total cross section exhibits quantized plateaus. Via a nonperturbative determination of the T matrix and an optical theorem which we prove here, we show that this behavior is universal for Rashba scattering off of any circularly symmetric, spin independent, finite-range potential. This is relevant both for impurity scattering in the noninteracting limit as well as for short-range two-particle scattering in the interacting problem.

  8. Scattering of ultrarelativistic electrons in ultrathin crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shul' ga, N.F., E-mail: shulga@kipt.kharkov.ua [National Science Center “Kharkov Institute of Physics and Technology”, 1, Akademichna str., Kharkiv, 61108 (Ukraine); Karazin Kharkiv National University, 4, Svobody sq., Kharkiv, 61000 (Ukraine); Shulga, S.N. [National Science Center “Kharkov Institute of Physics and Technology”, 1, Akademichna str., Kharkiv, 61108 (Ukraine); Karazin Kharkiv National University, 4, Svobody sq., Kharkiv, 61000 (Ukraine)

    2017-06-10

    Quantum theory is proposed of high energy electrons scattering in ultrathin crystals. This theory is based upon a special representation of the scattering amplitude in the form of an integral over the surface surrounding the crystal, and on the spectral method of determination of the wave function. The comparison is performed of quantum and classical differential scattering cross-sections in the transitional range of crystal thicknesses, from those at which the channeling phenomenon is not developed up to those at which it is established. It is shown that in this thickness range the quantum scattering cross-section, unlike the classical one, contains sharp peaks corresponding to some specific scattering angles, that is connected with the diffraction of the incident plane wave onto the periodically distributed crystal atomic strings. It is shown that the value of the scattering cross-section in the peaks varies periodically with the change of the target thickness. We note that this must lead to a new interference effect in radiation that is connected with the rearrangement of incident wave packet in transitional area of crystal thicknesses.

  9. Ps-atom scattering at low energies

    CERN Document Server

    Fabrikant, I I

    2015-01-01

    A pseudopotential for positronium-atom interaction, based on electron-atom and positron-atom phase shifts, is constructed, and the phase shifts for Ps-Kr and Ps-Ar scattering are calculated. This approach allows us to extend the Ps-atom cross sections, obtained previously in the impulse approximation [Phys. Rev. Lett. 112, 243201 (2014)], to energies below the Ps ionization threshold. Although experimental data are not available in this low-energy region, our results describe well the tendency of the measured cross sections to drop with decreasing velocity at $v<1$ a.u. Our results show that the effect of the Ps-atom van der Waals interaction is weak compared to the polarization interaction in electron-atom and positron-atom scattering. As a result, the Ps scattering length for both Ar and Kr is positive, and the Ramsauer-Townsend minimum is not observed for Ps scattering from these targets. This makes Ps scattering quite different from electron scattering in the low-energy region, in contrast to the inter...

  10. Scattering of ultrarelativistic electrons in ultrathin crystals

    Directory of Open Access Journals (Sweden)

    N.F. Shul'ga

    2017-06-01

    Full Text Available Quantum theory is proposed of high energy electrons scattering in ultrathin crystals. This theory is based upon a special representation of the scattering amplitude in the form of an integral over the surface surrounding the crystal, and on the spectral method of determination of the wave function. The comparison is performed of quantum and classical differential scattering cross-sections in the transitional range of crystal thicknesses, from those at which the channeling phenomenon is not developed up to those at which it is established. It is shown that in this thickness range the quantum scattering cross-section, unlike the classical one, contains sharp peaks corresponding to some specific scattering angles, that is connected with the diffraction of the incident plane wave onto the periodically distributed crystal atomic strings. It is shown that the value of the scattering cross-section in the peaks varies periodically with the change of the target thickness. We note that this must lead to a new interference effect in radiation that is connected with the rearrangement of incident wave packet in transitional area of crystal thicknesses.

  11. Low-energy positron scattering upon endohedrals

    Science.gov (United States)

    Amusia, M. Ya.; Chernysheva, L. V.

    2017-07-01

    We investigate positron scattering upon endohedrals and compare it with electron-endohedral scattering. We show that the polarization of the fullerene shell considerably alters the polarization potential of an atom, stuffed inside a fullerene. This essentially affects both the positron and electron elastic scattering phases as well as corresponding cross sections. Of great importance is also the interaction between the incoming positron and the target electrons that leads to formation of the virtual positronium P˜s. We illustrate the general trend by concrete examples of positron and electron scattering upon endohedrals He@C60 and Ar@C60, and compare it to scattering upon fullerene C60. To obtain the presented results, we have employed new simplified approaches that permit to incorporate the effect of fullerenes polarizability into the He@C60 and Ar@C60 polarization potential and to take into account the virtual positronium formation. Using these approaches, we obtained numeric results that show strong variations in shape and magnitudes of scattering phases and cross sections due to effect of endohedral polarization and P˜s formation.

  12. Thomson scattering using an atomic notch filter

    Science.gov (United States)

    Bakker, L. P.; Freriks, J. M.; de Hoog, F. J.; Kroesen, G. M. W.

    2000-05-01

    One of the biggest problems in performing Thomson scattering experiments in low-density plasmas is the very high stray light intensity in comparison with the Thomson scattering intensity. This problem is especially present in fluorescent lamps because of the proximity of the glass tube. We propose an atomic notch filter in combination with a dye laser and an amplified spontaneous emission (ASE) filter as a way of reducing this stray light level. The dye laser produces 589 nm radiation which is guided through the ASE filter that increases the spectral purity. The beam is then guided in the fluorescent lamp, where the Thomson scattering process takes place. The scattered light is collected and guided through a sodium vapor absorption cell, where the stray light is absorbed because it is resonant to the D2 transition of sodium. The spectral width of the Thomson scattering light is large enough to be transmitted through the absorption cell. In this way we only measure the Thomson scattering light.

  13. Treatment of age-related subfoveal choroidal neovascularization by low-dose external radiation. A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Harino, Seiyo; Oshima, Yusuke; Tsujikawa, Kaoru; Oh, Ami; Sugimoto, Kiyoshi [Yodogawa Christian Hospital, Osaka (Japan); Murayama, Shigeyuki; Inoue, Toshihiko

    1997-04-01

    We applied low dose external beam radiation (6MV) to 17 eyes of 17 patients (Mean age 70.9 years, range 58-85) who had subfoveal choroidal neovascularization associated with age-related macular degeneration. None of the cases were suitable for photocoagulation according to the Macular Photo-coagulation Study protocol, and no feeding vessels underlying choroidal neovascular membrane could be detected. Corrected visual acuity ranged from 0.02 to 0.6 before treatment. The patients were divided into two groups. One group of 11 eyes was treated with 10 Gy and the other group of 6 eyes with 21 Gy. Mean follow up period was 347{+-}89 (mean{+-}standard deviation) days in the 10 Gy group and 312{+-}100 days in the 21 Gy group. We evaluated the outcome as `effective` if no progression in neovascular membrane was found by ophthalmoscopic and angiographic examination. Only 3 eyes (21%) of patients in the 10 Gy group and 2 eyes (33%) in 21 Gy group showed any effect. Although the rate of progression in choroidal neovascular membrane was significantly smaller in the 10 and 21 Gy group than in the controls, the corrected visual acuity in the treated group was not improved over that of the controls. No serious complications were seen. Only one case showed a stabilized neovascular membrane in the control group of 7 patients. Although the present results seem to be worse than those in previous reports, the efficacy of this treatment still needs to be evaluated because no beneficial strategies in the treatment of subfoveal neovascularization have been established. (author)

  14. Proton dynamics in bacterial spores, a neutron scattering investigation

    Directory of Open Access Journals (Sweden)

    Noue Alexandre Colas de la

    2015-01-01

    Full Text Available Results from first neutron scattering experiments on bacterial spores are reported. The elastic intensities and mean square displacements have a non-linear behaviour as function of temperature, which is in agreement with a model presenting more pronounced variations at around 330 K (57 ∘C and 400 K (127 ∘C. Based on the available literature on thermal properties of bacterial spores, mainly referring to differential scanning calorimetry, they are suggested to be associated to main endothermic transitions induced by coat and/or core bacterial response to heat treatment.

  15. Hemorrhoids and varicose veins: a review of treatment options.

    Science.gov (United States)

    MacKay, D

    2001-04-01

    Hemorrhoids and varicose veins are common conditions seen by general practitioners. Both conditions have several treatment modalities for the physician to choose from. Varicose veins are treated with mechanical compression stockings. There are several over-the-counter topical agents available for hemorrhoids. Conservative therapies for both conditions include diet, lifestyle changes, and hydrotherapy which require a high degree of patient compliance to be effective. When conservative hemorrhoid therapy is ineffective, many physicians may choose other non-surgical modalities: injection sclerotherapy, cryotherapy, manual dilation of the anus, infrared photocoagulation, bipolar diathermy, direct current electrocoagulation, or rubber band ligation. Injection sclerotherapy is the non-surgical treatment for primary varicose veins. Non-surgical modalities require physicians to be specially trained, own specialized equipment, and assume associated risks. If a non-surgical approach fails, the patient is often referred to a surgeon. The costly and uncomfortable nature of treatment options often lead a patient to postpone evaluation until aggressive intervention is necessary. Oral dietary supplementation is an attractive addition to the traditional treatment of hemorrhoids and varicose veins. The loss of vascular integrity is associated with the pathogenesis of both hemorrhoids and varicose veins. Several botanical extracts have been shown to improve microcirculation, capillary flow, and vascular tone, and to strengthen the connective tissue of the perivascular amorphous substrate. Oral supplementation with Aesculus hippocastanum, Ruscus aculeatus, Centella asiatica, Hamamelis virginiana, and bioflavonoids may prevent time-consuming, painful, and expensive complications of varicose veins and hemorrhoids.

  16. Survey of background scattering from materials found in small-angle neutron scattering.

    Science.gov (United States)

    Barker, J G; Mildner, D F R

    2015-08-01

    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300-700 K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a 3He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scattering from solids. Background from the residual air in detector vacuum vessels and scattering from the 3He detector dome are presented. The thickness dependence of the multiple scattering correction for forward scattering from water is calculated. Inelastic phonon background scattering at small angles for crystalline solids is both modeled and compared with measurements. Methods of maximizing the signal-to-noise ratio by material selection, choice of sample thickness and wavelength, removal of inelastic background by TOF or Be filters, and removal of spin-flip scattering with polarized beam analysis are discussed.

  17. Modified discrete particle model of optical scattering in skin tissue accounting for multiparticle scattering.

    Science.gov (United States)

    Schneiderheinze, Dirk H P; Hillman, Timothy R; Sampson, David D

    2007-11-12

    We rigorously account for the effects of multiparticle light scattering from a fractal sphere aggregate in order to simulate the optical properties of a soft biological tissue, human skin. Using a computational method that extends Mie theory to the multisphere case, we show that multiparticle scattering significantly affects the computed optical properties, resulting in a reduction in both scattering coefficient and anisotropy for the wavelengths simulated, as well as a significantly enhanced forward peak in the simulated phase function. The model is extended to incorporate the contribution of Rayleigh scatterers, which we show is required to obtain reasonable agreement with experimentally measured optical properties of skin tissue.

  18. Scattering matrix measurements and light-scattering calculations of calcite particles

    Directory of Open Access Journals (Sweden)

    D. D. Dabrowska

    2011-09-01

    Full Text Available We present measurements of the complete scattering matrix as a function of the scattering angle of a sample of calcite particles collected near Lecce, Italy. The measurements are done at a wavelength of 647 nm in the scattering angle range 3°−177°. FESEM and SEM images show that the sample consists largely of flake-like particles. Ten different flake-like geometries are randomly generated and their scattering properties are simulated with DDA for sizes from 0.1 μm to 1 μm. Some preliminary comparisons of the simulations and the measurements are shown.

  19. Raman Scattering of Inorganic Fibers

    OpenAIRE

    SASAKI, Yoshiro; Sato, Mitsuhiko; OKAMURA, Kiyohito; NISHINA, Yuichiro

    1985-01-01

    We have examined evolution of Raman spectra of carbon fibers and SiC fibers through structural transformations caused by heat treatment. Raman spectra of the SiC fibers indicate that the fibers consist of amorphous or microcrystalline SiC and graphitic microcrystals. We discuss the correlation between the tensile strength of the fibers and their microscopic structure deduced from the Raman data.

  20. MO-AB-BRA-02: A Novel Scatter Imaging Modality for Real-Time Image Guidance During Lung SBRT

    Energy Technology Data Exchange (ETDEWEB)

    Redler, G; Bernard, D; Templeton, A; Chu, J [Rush University Medical Center, Chicago, IL (United States); Nair, C Kumaran [University of Chicago, Chicago, IL (United States); Turian, J [Rush University Medical Center, Chicago, IL (United States); Rush Radiosurgery LLC, Chicago, IL (United States)

    2015-06-15

    Purpose: A novel scatter imaging modality is developed and its feasibility for image-guided radiation therapy (IGRT) during stereotactic body radiation therapy (SBRT) for lung cancer patients is assessed using analytic and Monte Carlo models as well as experimental testing. Methods: During treatment, incident radiation interacts and scatters from within the patient. The presented methodology forms an image of patient anatomy from the scattered radiation for real-time localization of the treatment target. A radiographic flat panel-based pinhole camera provides spatial information regarding the origin of detected scattered radiation. An analytical model is developed, which provides a mathematical formalism for describing the scatter imaging system. Experimental scatter images are acquired by irradiating an object using a Varian TrueBeam accelerator. The differentiation between tissue types is investigated by imaging simple objects of known compositions (water, lung, and cortical bone equivalent). A lung tumor phantom, simulating materials and geometry encountered during lung SBRT treatments, is fabricated and imaged to investigate image quality for various quantities of delivered radiation. Monte Carlo N-Particle (MCNP) code is used for validation and testing by simulating scatter image formation using the experimental pinhole camera setup. Results: Analytical calculations, MCNP simulations, and experimental results when imaging the water, lung, and cortical bone equivalent objects show close agreement, thus validating the proposed models and demonstrating that scatter imaging differentiates these materials well. Lung tumor phantom images have sufficient contrast-to-noise ratio (CNR) to clearly distinguish tumor from surrounding lung tissue. CNR=4.1 and CNR=29.1 for 10MU and 5000MU images (equivalent to 0.5 and 250 second images), respectively. Conclusion: Lung SBRT provides favorable treatment outcomes, but depends on accurate target localization. A comprehensive

  1. High-precision positioning of radar scatterers

    Science.gov (United States)

    Dheenathayalan, Prabu; Small, David; Schubert, Adrian; Hanssen, Ramon F.

    2016-05-01

    Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy of synthetic aperture radar (SAR) scatterers in a 2D radar coordinate system, after compensating for atmosphere and tidal effects, is in the order of centimeters for TerraSAR-X (TSX) spotlight images. However, the absolute positioning in 3D and its quality description are not well known. Here, we exploit time-series interferometric SAR to enhance the positioning capability in three dimensions. The 3D positioning precision is parameterized by a variance-covariance matrix and visualized as an error ellipsoid centered at the estimated position. The intersection of the error ellipsoid with objects in the field is exploited to link radar scatterers to real-world objects. We demonstrate the estimation of scatterer position and its quality using 20 months of TSX stripmap acquisitions over Delft, the Netherlands. Using trihedral corner reflectors (CR) for validation, the accuracy of absolute positioning in 2D is about 7 cm. In 3D, an absolute accuracy of up to ˜ 66 cm is realized, with a cigar-shaped error ellipsoid having centimeter precision in azimuth and range dimensions, and elongated in cross-range dimension with a precision in the order of meters (the ratio of the ellipsoid axis lengths is 1/3/213, respectively). The CR absolute 3D position, along with the associated error ellipsoid, is found to be accurate and agree with the ground truth position at a 99 % confidence level. For other non-CR coherent scatterers, the error ellipsoid concept is validated using 3D building models. In both cases, the error ellipsoid not only serves as a quality descriptor, but can also help to associate radar scatterers to real-world objects.

  2. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  3. Generalizations of Karp's theorem to elastic scattering theory

    Science.gov (United States)

    Tuong, Ha-Duong

    Karp's theorem states that if the far field pattern corresponding to the scattering of a time-harmonic acoustic plane wave by a sound-soft obstacle in R2 is invariant under the group of rotations, then the scatterer is a circle. The theorem is generalized to the elastic scattering problems and the axisymmetric scatterers in R3.

  4. Determination of optical scattering properties of highly-scattering media in optical coherence tomography images

    DEFF Research Database (Denmark)

    Levitz, D.; Thrane, L.; Frosz, Michael Henoch

    2004-01-01

    We developed a new algorithm that fits optical coherence tomography (OCT) signals as a function of depth to a general theoretical OCT model which takes into account multiple scattering effects. With use of this algorithm, it was possible to extract both the scattering coefficient and anisotropy...

  5. Small angle neutron scattering and small angle X-ray scattering ...

    Indian Academy of Sciences (India)

    Abstract. The morphology of carbon nanofoam samples comprising platinum nanopar- ticles dispersed in the matrix was characterized by small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) techniques. Results show that the structure of pores of carbon matrix exhibits a mass (pore) fractal nature ...

  6. Wavefield separation by energy norm Born scattering

    KAUST Repository

    Sun, Bingbing

    2017-08-17

    In Reflection Based Waveform Inversion, the gradient is computed by cross-correlating the direct and Born scattered wavefield with their adjoints applied to the data residuals. In this case, the transmitted part of the Born scattered wavefield produces high wavenumber artifacts, which would harm the convergence of the inversion process. We propose an efficient Energy Norm Born Scattering (ENBS) to attenuate the transmission components of the Born modeling, and allow it to produce only reflections. ENBS is derived from the adjoint of the Energy Norm (inverse scattering) imaging condition and in order to get deeper insights of how this method works, we show analytically that given an image, in which reflectivity is represented by a Dirac delta function, ENBS attenuates transmission energy perfectly. We use numerical examples to demonstrate that ENBS works in both the time and the frequency domain. We also show that in reflection waveform inversion (RWI) the wave path constructed by ENBS would be cleaner and free of high wavenumber artifacts associated with conventional Born scattering.

  7. Progress report on neutron scattering at JAERI

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-10-01

    In the first half of fiscal year 1997, JRR-3M was operated for 97 days followed by a long term shut down for its annual maintenance. Three days were lost out of 100 scheduled operation days, due to a trouble in irradiation facility. Neutron scattering research activities at the JRR-3M have been extended from that of fiscal year 1996. In the Research Group for Quantum Condensed Matter System, experimental study under high pressures, low temperatures and high fields as well as coupling of these conditions were planned to find new quantum condensed matter systems. And, obtained experimental results were immediately provided to theorists for their investigations. In cooperation with new group, Research Group for Neutron Scattering of Strongly Correlated Electron Systems and Research Group for Neutron Scattering at Ultralow Temperatures were carrying neutron scattering experiments at JRR-3M. Research Group for Neutron Crystallography in Biology had opened a way for investigating biomatter neutron diffraction research with high experimental accuracy by growing a millimeter-class large single crystal. In fiscal year 1997, 39 research projects were conducted by these four groups and other staffs in JAERI, 27 projects collaborated with university researchers and 3 projects collaborated with private enterprises were also conducted as complementary researches. 2117 days of machine times were requested to use 8 neutron scattering instruments this year, which corresponded to 1.51 times larger than those planned at its beginning. (G.K.)

  8. Magnetization dissipation in ferromagnets from scattering theory

    Science.gov (United States)

    Brataas, Arne; Tserkovnyak, Yaroslav; Bauer, Gerrit E. W.

    2011-08-01

    The magnetization dynamics of ferromagnets is often formulated in terms of the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation describes the response of the magnetization in terms of effective fields, whereas the dissipative part is parametrized by the Gilbert damping tensor. We formulate a scattering theory for the magnetization dynamics and map this description on the linearized LLG equation by attaching electric contacts to the ferromagnet. The reactive part can then be expressed in terms of the static scattering matrix. The dissipative contribution to the low-frequency magnetization dynamics can be described as an adiabatic energy pumping process to the electronic subsystem by the time-dependent magnetization. The Gilbert damping tensor depends on the time derivative of the scattering matrix as a function of the magnetization direction. By the fluctuation-dissipation theorem, the fluctuations of the effective fields can also be formulated in terms of the quasistatic scattering matrix. The theory is formulated for general magnetization textures and worked out for monodomain precessions and domain-wall motions. We prove that the Gilbert damping from scattering theory is identical to the result obtained by the Kubo formalism.

  9. German neutron scattering conference. Programme and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas (ed.)

    2012-07-01

    The German Neutron Scattering Conference 2012 - Deutsche Neutronenstreutagung DN 2012 offers a forum for the presentation and critical discussion of recent results obtained with neutron scattering and complementary techniques. The meeting is organized on behalf of the German Committee for Research with Neutrons - Komitee Forschung mit Neutronen KFN - by the Juelich Centre for Neutron Science JCNS of Forschungszentrum Juelich GmbH. In between the large European and international neutron scattering conferences ECNS (2011 in Prague) and ICNS (2013 in Edinburgh), it offers the vibrant German and international neutron community an opportunity to debate topical issues in a stimulating atmosphere. Originating from ''BMBF Verbundtreffen'' - meetings for projects funded by the German Federal Ministry of Education and Research - this conference series has a strong tradition of providing a forum for the discussion of collaborative research projects and future developments in the field of research with neutrons in general. Neutron scattering, by its very nature, is used as a powerful probe in many different disciplines and areas, from particle and condensed matter physics through to chemistry, biology, materials sciences, engineering sciences, right up to geology and cultural heritage; the German Neutron Scattering Conference thus provides a unique chance for exploring interdisciplinary research opportunities. It also serves as a showcase for recent method and instrument developments and to inform users of new advances at neutron facilities.

  10. Electron elastic scattering off endo-fullerenes

    Science.gov (United States)

    Dolmatov, Valeriy

    2017-04-01

    The given presentation highlights the physically transparent, relatively simple, and yet reasonably complete approximation to the problem of low-energy electron elastic scattering off endohedral fullerenes A@CN along with corresponding findings unraveled on its basis. It is believed that, as of today, the highlighted results provide the most complete information about features of e + A @CN elastic scattering brought about by the fullerene-cage-related, correlation-related, and polarization-related impacts of the individual and coupled members of the A@C60 target on the scattering process. Each of the impacts is shown to bring spectacular features into e + A @C60 scattering. A remarkable inherent quality of the developed approximation is its ability to account for mutual coupling between electronic excited configurations of CN with those of the encapsulated atom A without reference to complicated details of the electronic structure of CN itself. Spectacular effects in the scattering process, primarily associated with polarization of A@C60 by an incident electron, are thoughtfully detailed both quantitatively and qualitatively in a physically transparent manner for ease of understanding and convenience of the audience. This study was performed in collaboration with Professors M. Ya. Amusia, L. V. Chernysheva, and UNA undergraduate students. The past support by the NSF Grant PHY-1305085 is acknowledged.

  11. Muon Elastic Scattering with MUSE at PSI

    Directory of Open Access Journals (Sweden)

    Kohl M.

    2014-03-01

    Full Text Available The proton radius puzzle is the disagreement between the much more precise radius determined from muonic hydrogen spectroscopy and the numerous atomic hydrogen and electron scattering determinations. The puzzle has several possible resolutions, including physics beyond the Standard Model, missing conventional physics, and errors or underestimated uncertainties in the extraction of the radius from the data. New experiments are needed to confirm and / or resolve the puzzle. The MUon Scattering Experiment (MUSE recently approved at PSI has been designed to help resolve the puzzle by measuring the radius in a way not yet done. Similar to electron scattering, the radius will be extracted from the observed change of the charge form factor with momentum transfer. The experiment uses the πM1 beamline to provide a mixed secondary muon and electron (and pion beam of either positive or negative charge. The comparison of muon and electron scattering measured simultaneously determines the consistency of the form factors in the two cases with high precision. Comparison of yields from both charge signs will at the same time disentangle the effect of two-photon exchange. The proton charge radius can be extracted from each set of scattering data. The physics case and status of MUSE will be discussed.

  12. Study on choroidal neovascularization with anti-VEGF treatment in the mouse retina using optical coherence tomography angiography (Conference Presentation)

    Science.gov (United States)

    Park, Jang Ryul; Choi, WooJhon; Kim, Jaeryung; Hong, Hye Kyong; Kim, Yongjoo; Hwang, Yoonha; Park, Sang Jun; Woo, Se Joon; Kim, Pilhan; Park, Kyu Hyung; Koh, Gou Young; Oh, Wang-Yuhl

    2017-02-01

    To understand the pathogenesis of ophthalmic disease, utilizing small animal models such as mouse is necessary because of their ease of maintenance and availability. For identifying pathophysiology and drug development of retinal diseases in mouse model, optical coherence tomography angiography (OCTA) is promising imaging modality visualizing not only microstructure but also microvasculature. In this study, we serially imaged 3D structure and angiography of laser-induced choroidal neovascularization (CNV) in the mouse retina with/without anti-VEGF treatment. Also, the volume changes of CNV and avascular region in choroid layer are measured for identifying effects of anti-VEGF. A lab-built high-speed OCTA prototype using the wavelength-swept laser centered at 1040 nm with 230 kHz A-scan rate acquired 3-D volumetric data consisted of 1024 x 1024 x 3 A-scans. The OCTA scanned 1.7 mm x 1.7 mm area around ONH. For obtaining angiography, amplitude decorrelation from 3 consecutive B-scans at each position was generated. Seven days after the laser photocoagulation at mouse retina for generation of the laser-induced CNV, intravitreal administration of Fc and VEGF-Trap was given in the therapeutic arm. The OCTA were performed at 6, 14, 21 and 35 days after laser photocoagulation. Vasculatures of inner retina, outer retina and choroid layers were separately visualized after RPE flattening and layer segmentation. To investigate therapeutic effects of anti-VEGF treatment, the relative area and volume of CNV in outer retina layer is measured. Also, total volume of avascular zone surrounding the laser injury site in choroid layer is also analyzed.

  13. Analysis of neutron scattering data: Visualization and parameter estimation

    Energy Technology Data Exchange (ETDEWEB)

    Beauchamp, J.J.; Fedorov, V.; Hamilton, W.A.; Yethiraj, M.

    1998-09-01

    Traditionally, small-angle neutron and x-ray scattering (SANS and SAXS) data analysis requires measurements of the signal and corrections due to the empty sample container, detector efficiency and time-dependent background. These corrections are then made on a pixel-by-pixel basis and estimates of relevant parameters (e.g., the radius of gyration) are made using the corrected data. This study was carried out in order to determine whether treatment of the detector efficiency and empty sample cell in a more statistically sound way would significantly reduce the uncertainties in the parameter estimators. Elements of experiment design are shortly discussed in this paper. For instance, we studied the way the time for a measurement should be optimally divided between the counting for signal, background and detector efficiency. In Section 2 we introduce the commonly accepted models for small-angle neutron and x-scattering and confine ourselves to the Guinier and Rayleigh models and their minor generalizations. The traditional approaches of data analysis are discussed only to the extent necessary to allow their comparison with the proposed techniques. Section 3 describes the main stages of the proposed method: visual data exploration, fitting the detector sensitivity function, and fitting a compound model. This model includes three additive terms describing scattering by the sampler, scattering with an empty container and a background noise. We compare a few alternatives for the first term by applying various scatter plots and computing sums of standardized squared residuals. Possible corrections due to smearing effects and randomness of estimated parameters are also shortly discussed. In Section 4 the robustness of the estimators with respect to low and upper bounds imposed on the momentum value is discussed. We show that for the available data set the most accurate and stable estimates are generated by models containing double terms either of Guinier's or Rayleigh

  14. Parameterization of single-scattering properties of snow

    Science.gov (United States)

    Räisänen, Petri; Kokhanovsky, Alexander; Guyot, Gwennole; Jourdan, Olivier; Nousiainen, Timo

    2015-04-01

    provides a substantially better basis for representing the single-scattering properties of snow than spheres do. Moreover, the parameterizations developed here are analytic and simple to use, and they can also be applied to the treatment of dirty snow following (e.g.) the approach of Kokhanovsky (The Cryosphere, 7, 1325-1331, doi:10.5194/tc-7-1325-2013, 2013). This should make them an attractive option for use in radiative transfer applications involving snow.

  15. Determination of interfacial roughness using X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Munkholm, Anneli [Stanford Univ., CA (United States)

    1997-05-01

    Crystal truncation rod (CTR) scattering is shown to be a powerful technique for determining interfacial roughness non-destructively. By measuring the decay of scattering away from a Bragg reflection in the surface direction an rms roughness of the surface or interface can be extracted. The authors obtain rms roughness values with an accuracy of ± 0.1 Å. Sensitivity to lateral length scale roughness ranges from the wavelength of the x-rays to between 1,000--10,000 Å depending on the instrument function and the specific truncation rod. The influence of different cleans, as well as the thermal oxidation process, on the Si-SiO2 interface is investigated. A hot water treatment prior to the thermal oxidation is shown to roughen the Si-SiO2 interface. CTR scattering results also show a smoothing of the interface as a result of the oxidation process even for as little as 60 Å of thermal oxidation. Comparison between AFM and CTR scattering gives a consistent picture of the relative roughness of the wafers, although the absolute numbers do not agree. The differences in the absolute values can be explained by the lateral roughness scale that the two techniques measure, indicating that it is at periodicities below ~ 100 Å that the increased roughness observed by the x-ray is found. Crystal truncation rods are shown to be perpendicular to the surface and not along the crystallographic axes of a miscut crystal. It is shown that for a crystal terminated by a regular step array both an atomistic and a continuum description of CTR scattering give identical results. Furthermore, the atomistic approach is used to show that a diamond cubic surface with a miscut is inherently rough. Even for a small miscut the tilt of the CTR with respect to the crystallographic axes results in complications for measuring the rod intensity. The authors present schemes for determining the exact position of the CTR in reciprocal space and for measuring the miscut of a single

  16. Introduction to neutron scattering. Lecture notes of the introductory course

    Energy Technology Data Exchange (ETDEWEB)

    Furrer, A. [ed.

    1996-12-31

    These proceedings enclose ten papers presented at the 1. European Conference on Neutron scattering (ECNS `96). The aim of the Introductory Course was fourfold: - to learn the basic principles of neutron scattering, - to get introduced into the most important classes of neutron scattering instruments, -to learn concepts and their transformation into neutron scattering experiments in various fields of condensed matter research, - to recognize the limitations of the neutron scattering technique as well as to the complementarity of other methods. figs., tabs., refs.

  17. Inelastic pion scattering by /sup 13/C at low energies

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J.H.

    1987-03-01

    Angular distributions for inelastically scattered pions were obtained for several states in /sup 13/C at an incident energy of 65 MeV. The data include results from both ..pi../sup +/ and ..pi../sup -/ measurements. In addition, ..pi../sup -/ measurements were made at T/sub ..pi../ = 50 MeV at one angle to give a two point fixed-q excitation function. The data are compared to theory and the data of others. As might be expected, medium corrections are shown to be considerably more important at low energies than at resonance. This is true for inelastic transitions of multipolarity 0,2 and 3. Parameters derived from an analysis of elastic pion scattering and SCX data also provide an adequate description of the inelastic transitions. The charge asymmetry in the cross sections for the 9/2/sup +/ state that was seen at resonance persists at these energies. This result is consistent with an impulse approximation treatment of the spin-flip amplitude. This is true even though the incoming energy of the pions is far below the range where the validity of an impulse treatment is expected. 65 refs., 45 figs.

  18. Inverse Scattering Approach to Improving Pattern Recognition

    Energy Technology Data Exchange (ETDEWEB)

    Chapline, G; Fu, C

    2005-02-15

    The Helmholtz machine provides what may be the best existing model for how the mammalian brain recognizes patterns. Based on the observation that the ''wake-sleep'' algorithm for training a Helmholtz machine is similar to the problem of finding the potential for a multi-channel Schrodinger equation, we propose that the construction of a Schrodinger potential using inverse scattering methods can serve as a model for how the mammalian brain learns to extract essential information from sensory data. In particular, inverse scattering theory provides a conceptual framework for imagining how one might use EEG and MEG observations of brain-waves together with sensory feedback to improve human learning and pattern recognition. Longer term, implementation of inverse scattering algorithms on a digital or optical computer could be a step towards mimicking the seamless information fusion of the mammalian brain.

  19. Radiative MRI Coil Design Using Parasitic Scatterers

    DEFF Research Database (Denmark)

    Sanchez-Heredia, Juan D.; Avendal, Johan; Bibic, Adnan

    2018-01-01

    Conventionally, radiofrequency (RF) coils used for magnetic resonance imaging (MRI) are electrically small and designed for nearfield operation. Therefore, existing antenna design techniques are mostly irrelevant for RF coils. However, the use of higher frequencies in ultrahigh field (UHF) MRI...... allows for antenna design techniques to be adapted to RF coil designs. This study proposes the use of parasitic scatterers to improve the performance of an existing 7T MRI coil called the single-sided adapted dipole (SSAD) antenna. The results reveal that scatterers arranged in a Yagi fashion can...... suitable for use in high density arrays. These findings show the potential of parasitic scatterers as an effective method to improve the performance of existing radiative MRI coils....

  20. Electromagnetic wave scattering from some vegetation samples

    Science.gov (United States)

    Karam, Mostafa A.; Fung, Adrian K.; Antar, Yahia M.

    1988-01-01

    For an incident plane wave, the field inside a thin scatterer (disk and needle) is estimated by the generalized Rayleigh-Gans (GRG) approximation. This leads to a scattering amplitude tensor equal to that obtained via the Rayleigh approximation (dipole term) with a modifying function. For a finite-length cylinder the inner field is estimated by the corresponding field for the same cylinder of infinite lenght. The effects of different approaches in estimating the field inside the scatterer on the backscattering cross section are illustrated numerically for a circular disk, a needle, and a finite-length cylinder as a function of the wave number and the incidence angle. Finally, the modeling predictions are compared with measurements.