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Sensitivity Measurements (sensitivity + measurement)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Corneal mechanical sensitivity measurement using a staircase technique

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2005
Blanka Golebiowski
Abstract Purpose:, To determine the repeatability of an unequal staircase technique (Garcia-Perez Staircase, GPS) to measure corneal mechanical threshold using the CRCERT-Belmonte Aesthesiometer, and to compare this with a previously-reported psychophysical method (Method of Constant Stimuli, MOCS). Methods:, The GPS, utilising unequal ascending and descending steps, was used to obtain a threshold measurement from the mean of six response reversals. Repeatability was determined for the GPS and MOCS methods (n = 14), and threshold results obtained with each method were compared (n = 10). Results:, The GPS (65.0 ± 16.9 mL min,1; CoR ± 18.3 mL min,1) method was more repeatable than the MOCS (64.0 ± 15.7 mL min,1; CoR ± 37.3 mL min,1) and the absolute values obtained with the two methods were not significantly different. Conclusions:, Although each method gave equivalent threshold results, the GPS method was more repeatable and quicker to apply and hence should reduce the influence of patient fatigue and help to minimise possible carry-over effects. [source]

Studies on Energetic Compounds Part,27: Kinetics and Mechanism of Thermolysis of Bis(Ethylenediamine)Metal Nitrates and Their Role in the Burning Rate of Solid Propellants

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2003
Gurdip Singh
Abstract Four bis(ethylenediamine)metal(II) nitrate (BEMN) complexes, i.e. [M(EDA)2](NO3)2, where M=Cu, Co, Ni and Zn, have been prepared and characterized. Thermolysis of these complexes induced by heat and drop-weight impact has been investigated by TG-DTG, DTA, explosion delay (DE), explosion temperature (TE) and impact sensitivity measurement. The kinetics of early thermolysis reaction prior to fast decomposition have been evaluated. Contracting area (CA, n=2) and contracting cube (CC, n=3) equations were found to give the best fits in isothermal TG data among all tested nine mechanism-based kinetic models. The values of activation energy (Ea), TE, DE and activation energy for explosion (E*) have been found to be quite lower for the copper complex as compared to cobalt, nickel and zinc complexes. A mechanism of thermolysis has also been proposed. All these complexes were found to be insensitive towards impact of 2,kg weight up to the height of 110,cm. These complexes were used as energetic burning rate modifiers in the combustion of hydroxy-terminated polybutadiene (HTPB)-ammonium perchlorate (AP) composite solid propellants. A two-fold increase in burning rate was observed with copper and cobalt complexes at low concentration (2% by wt.). The in situ freshly formed metal oxides with large number of active sites in their crystallites seem to be better additives for combustion of propellants. [source]

Rapid review of liquid-based smears as a quality control measure

DIAGNOSTIC CYTOPATHOLOGY, Issue 3 2004
Sheryl Henderson M.Med.Sc.(Cytol.)
Abstract The objective of this study was to investigate the effectiveness of a standardized method of rapid review (RR) of monolayer preparations for the identification of abnormalities, the presence of an endocervical component and infectious agents. A total of 200 ThinPrep (Cytyc, Boxborough, MA) slides representing the spectrum of abnormalities commonly encountered in cervical/vaginal cytologic specimens was retrieved from archive. The study set comprised 129 cases within normal limits (WNL); 36 low-grade epithelial abnormalities (LGEA); 28 high-grade epithelial abnormalities (HGEA), including 2 endocervical adenocarcinomas in situ (AIS) and 7 carcinomas. Eighteen false negative (FN) cases were also included for study. Originally missed on initial review, these cases were found to be abnormal on quality control review (17 LGEA; 1 AIS). Commonly encountered infectious agents were represented and included Candida albicans, Trichomonas vaginalis, herpes simplex virus, and Actinomyces. The slides were reviewed using a standardized method of RR (turret technique, for 60 sec) by three experienced screeners masked to the original reference diagnosis. Median sensitivity for LGEA was 70% (range, 67,72%); HGEA, 69% (range, 54,80%); and FN, 65% (range, 56,78%). Specificity remained high, median specificity for LGEA was 95%; HGEA, 97%; and FN, 100%. There was no significant overcalling of any diagnostic category. The chi-square test at P < 0.05 showed no significant difference between RR and full manual rescreen of the ThinPrep smears in this study. While no statistical difference was proven, the sensitivity measurements for all categories of abnormality were moderate due to the high proportion of atypical cases included into the study set. Abnormalities on the monolayer preparations frequently displayed fewer, smaller groups of disaggregated cells with rounded cytoplasmic outlines that were difficult to discern on RR. Interobserver variation was noted. Monolayers with a paucity of diagnostic cells and those displaying subtle nuclear atypia were often overlooked. Diagn. Cytopathol. 2004;31:141,146. © 2004 Wiley-Liss, Inc. [source]

Ocular wavefront analysis and contrast sensitivity in eyes implanted with AcrySof IQ or AcrySof Natural intraocular lenses

ACTA OPHTHALMOLOGICA, Issue 7 2009
Tamer Takmaz
Abstract. Purpose:, This study aimed to compare ocular wavefront aberrations for pupil diameters of 4 mm and 6 mm, and contrast sensitivity, in eyes with AcrySof IQ and AcrySof Natural intraocular lenses (IOLs). Methods:, Sixty eyes of 60 patients were enrolled in this prospective randomized study. After phacoemulsification the eyes received either AcrySof IQ SN60WF or AcrySof Natural SN60AT IOLs. One month after surgery, all patients underwent complete ophthalmological examination including corneal topography, wavefront analysis for pupil diameters of 4 mm and 6 mm, and contrast sensitivity measurements with the CSV 1000E instrument under photopic and mesopic conditions with and without glare. Results:, There was no statistically significant difference between groups in age, sex or other preoperative ocular characteristics (p > 0.05). Patients with AcrySof IQ IOLs had higher contrast sensitivity at 6 c.p.d. under photopic conditions, at 6 c.p.d. and 18 c.p.d. under mesopic conditions, and at 6 c.p.d., 12 c.p.d. and 18 c.p.d. under mesopic conditions with glare (p < 0.05). Corneal spherical aberration was 0.273 ± 0.074 ,m in the AcrySof Natural group and 0.294 ± 0.086 ,m in the AcrySof IQ group (p = 0489). Ocular spherical aberration was 0.362 ± 0.141 ,m and 0.069 ± 0.043 ,m (p < 0.001) for 6-mm diameter pupils and 0.143 ± 0.091 ,m and 0.017 ± 0.016 ,m (p < 0.001) for 4-mm diameter pupils, with AcrySof Natural and AcrySof IQ IOLs, respectively. There were no significant differences in other higher-order aberrations between the groups (p > 0.05). Conclusions:, Aspherical AcrySof IQ IOLs significantly reduced spherical aberration for pupil diameters of both 4 mm and 6 mm and also improved contrast sensitivity more than spherical AcrySof Natural IOLs, especially in mesopic conditions. [source]

Alterations of the ocular surface epithelial mucins 1, 2, 4 and the tear functions in patients with atopic keratoconjunctivitis

CLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2006
M. Dogru
Summary Background An increased understanding of the ocular surface alterations at the cellular level in the conjunctiva and the cornea, may help explain the pathogenesis and the subsequent clinical appearance of atopic ocular allergies, which may be potentially blinding. Purpose To investigate MUC 1, 2 and 4 alterations, tear function and the ocular surface disorder in patients with atopic keratoconjunctivitis. Methods Twenty-eight eyes of 14 atopic keratoconjunctivitis patients as well as 22 eyes of 11 age-and sex-matched normal subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer's test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface, conjunctival impression cytology and brush cytology. Impression cytology samples underwent periodic acid-Schiff and immunohistochemical staining with MUC 1, 2 and 4 antibodies. Brush cytology specimens underwent evaluation for inflammatory cell numbers and quantitative real-time-PCR for MUC 1, 2 and 4 mRNA expression. Patient eyes with fluorescein and Rose Bengal scores greater than four points were regarded to have significant epithelial disease in this study. Results The mean corneal sensitivity and BUT values were significantly lower in atopic patients with significant epithelial disease, compared with patients with insignificant epithelial disease and controls (P<0.01). Brush cytology specimens from patients with significant epithelial disease revealed significantly higher numbers of inflammatory cells (P<0.01). Specimens from patient eyes showed positive staining for MUC 1, 2 and 4. MUC 1, 2 and 4 mRNA expressions were significantly higher in eyes with significant epithelial disease compared with eyes with insignificant epithelial disease and eyes of control subjects. Conclusion Ocular surface inflammation, decline in corneal sensitivity, tear film instability, changes in conjunctival epithelial MUC 1, 2 and 4 mRNA expressions were thought to be important in the pathogenesis of atopic ocular surface disease. [source]