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1.
Eur J Orthop Surg Traumatol ; 32(3): 405-411, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33895897

RESUMEN

PURPOSE: The current indication for comminuted radial head fractures is radial head arthroplasty (RHA). The main purpose of this study was to investigate any statistical differences in terms of prosthesis revision or removal and radiographic degenerative changes by comparing patients who underwent RHA and ligaments repair to those who underwent only RHA implant at minimum two years follow-up. The secondary aim was to delineate a trend profile of RHA implants. METHODS: All patients who underwent RHA surgery for traumatic pathology between January 2012 and December 2017 were eligible. Two researchers independently and retrospectively reviewed the patients' charts and collected the following data: type of prosthesis, associated surgical procedures and revision surgery. They also looked for any radiographic sign of prosthesis loosening, overstuffing, capitellar osteopenia, heterotopic ossification and degenerative changes. No clinical evaluation was performed. RESULTS: In 6 years, 124 RHA were implanted (74 female, 50 male, mean age 56). The main diagnoses were: terrible triad, trans-olecranon fracture and isolated radial head fracture. It was found no significant statistical difference between the 2 groups; nevertheless, the cohort of patients that underwent ligaments repair had a lower revision rate in comparison with the other. Suture of the annular ligament seems to be critical. The overall revision rate was 10.5%. CONCLUSION: This multi-center study found no evidence that ligaments repair, as an associated surgical procedure, improves RHA longevity, except for annular ligament. Nevertheless, it seems to prevent degenerative changes at midterm follow-up.


Asunto(s)
Articulación del Codo , Fracturas del Radio , Artroplastia , Articulación del Codo/cirugía , Femenino , Estudios de Seguimiento , Humanos , Ligamentos , Masculino , Persona de Mediana Edad , Fracturas del Radio/complicaciones , Fracturas del Radio/diagnóstico por imagen , Fracturas del Radio/cirugía , Rango del Movimiento Articular , Estudios Retrospectivos , Resultado del Tratamiento
2.
Klin Monbl Augenheilkd ; 232(4): 477-81, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25902101

RESUMEN

BACKGROUND: Clinical assessment of dark adaptation is time consuming and requires a specialised instrumentation such as a nyktometer. It is therefore not surprising that dark adaptation is rarely tested in practice. As for the case of testing fitness of a driver, demands on adaptation in daily driving tasks mostly depart from settings in a nyktometer. In daily driving, adaptation is stressed by high and fast transitions of light levels, and the period of time which is relevant to safe driving starts right after a transition and ends several seconds later. In the nyktometer dark adaptation is tested after completion of the adaptation process. RESULTS of a nyktometer test may therefore deliver little information about adaptation shortly after light transitions. In an attempt to develop a clinical test aiming to fulfill both a short measurement time and offering test conditions comparable to conditions in driving, we conducted a preliminary study in which contrast sensitivity thresholds were recorded for light transitions as found in daily driving tasks and for various times after transition onsets. Contrast sensitivity performance is compared to dark adaptation performance as assessed by a myktometer. MATERIAL AND METHODS: Contrast sensitivity thresholds were recorded in 17 participants by means of a twin projection apparatus. The apparatus enabled the projection of an adapting field and of a Landolt ring both with a variable luminance. Five different stepwise transitions in levels of adapting luminance were tested. All transitions occurred from bright to dark. The Landolt ring was flashed 100 or 500 ms after the transition had occurred. Participants were instructed to report the orientation of the Landolt ring. A Rodenstock Nyktometer, Plate 501, was used to record dark adaptation threshold. RESULTS: Experimental data from the proposed test revealed a noticeably increasing contrast detection threshold measured in dark adaptation in the stronger transition from 14 000 to 8 cd/m2 than in the weaker transition from 2000 to 8 cd/m2. By raising the dark adaption luminance level from 8 to 60 cd/m2 in the stronger transition case, the contrast detection threshold was then improved by a factor of four. Another main finding showed that for the adaptation process from strong glare stimuli to the dark adaptation, a peak deterioration in contrast sensitivity occurred at the light adaptation level of 6000 cd/m2. Comparing the contrast performance assessed by the proposed test with that of the nyktometer test, there was no clear correlation between the two methods. CONCLUSIONS: Our suggested method to assess dark adaptation performance proved to be practical in use and, since the patient does not have to spend a long time to attain complete dark adaptation, the method required a short time for measurement. Our negative experience in the use of the myktometer was in agreement with reported experience in the literature.


Asunto(s)
Examen de Aptitud para la Conducción de Vehículos , Sensibilidad de Contraste/fisiología , Adaptación a la Oscuridad/fisiología , Iluminación/métodos , Visión Nocturna/fisiología , Pruebas de Visión/métodos , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Luminosa/métodos , Proyectos Piloto , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
3.
Klin Monbl Augenheilkd ; 230(4): 349-52, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23629777

RESUMEN

BACKGROUND: Large-scale examinations are costly and time consuming. Costs could be reduced by asking patients to carry out tests by themselves. This study aimed to gain practical experience on how patients handle self-administered acuity tests. MATERIAL AND METHODS: We developed two computerized self-test acuity screening devices consisting out of a commercially available vision screener, an answering box and a PC. The answering box served to record the responses of the participants and to present verbal instructions to the participants. Participants took acuity tests for far (5 m, OS, OD, OU) and an acuity test for near (40 cm, OU) using the self-test screener. For the reason of privacy personal data like age, gender and habitual correction was entered on a separate PC. The devices were installed in two different locations and run without supervision. RESULTS: Personal data records of 2528 participants (4% women) were collected in both locations. The age in 45% of the participants ranged between 41 and 50 years. 31% of the participants declared to wear spectacles and 3% contact lenses. 66% of participants declared not to need a correction. A total of 1078 participants completed four acuity tests (OD far, OS far, OU far, OD near) using the self-test screening device. Depending on the acuity test and location, the average duration required to complete one acuity test ranged between 29.7 s to 39.1 s. The total duration for completing the four acuity tests was on average 133 ± 46 s. CONCLUSIONS: The duration for completing the acuity tests is considered as being short. Made experience speaks in favor of feasibility of self-tests in acuity screening.


Asunto(s)
Diagnóstico por Computador/estadística & datos numéricos , Autoevaluación Diagnóstica , Interfaz Usuario-Computador , Selección Visual/estadística & datos numéricos , Agudeza Visual , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Suiza/epidemiología , Selección Visual/métodos
4.
Ergonomics ; 55(11): 1331-9, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22928619

RESUMEN

We developed a test for screening visual skills under similar conditions as at workplace. The test was administered to 207 participants, recruited in the working population. Six-digit numbers were super-imposed on a video of a drive and presented for 300 ms in the central visual field and in the periphery. Participants reported whether or not the integer '3' was included in the numbers. Normative data for the test were computed using 150 data sets of participants reporting not to take drugs and with an age ranging between 15 y and 67 y. Participants performed better in the central visual field than in periphery. The test could successfully be completed by participants of all ages without the need of adjustment of settings. Comparison of 46 data sets recorded in participants taking drugs (30 y-68 y) with age matched participants not taking drugs demonstrates an additional potential application of the test. Practitioner Summary: Developed test delivers comparative estimates of visual skills within short time and appears as valuable and cheap complementation to current testing procedures in industrial practice. The test can be used in a preventive and in educative manner to monitor effects of factors like fatigue, sleep deprivation or drug consumption.


Asunto(s)
Selección Visual/métodos , Agudeza Visual/fisiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Femenino , Humanos , Masculino , Persona de Mediana Edad , Suiza , Lugar de Trabajo , Adulto Joven
5.
Biomed Res Int ; 2016: 6481028, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27999807

RESUMEN

Background. Visceral leishmaniasis (VL) caused by Leishmania infantum is endemic in the Mediterranean area. In the last decades a northward spread of the parasite has been observed in Italy. This paper describes a VL outbreak in Modena province (Emilia-Romagna, Northern Italy) between 2012 and 2015. Methods. Retrospective, observational study to evaluate epidemiological, microbiological characteristics, and clinical management of VL in patients referring to Policlinico Modena Hospital. Results. Sixteen cases of VL occurred in the study period. An immunosuppressive condition was present in 81.3%. Clinical presentation included anemia, fever, leukopenia, thrombocytopenia, and hepatosplenomegaly. Serology was positive in 73.3% of cases, peripheral blood PCR in 92.3%, and bone marrow blood PCR in 100%. Culture was positive in 3/6 cases (50%) and all the isolates were identified as L. infantum by ITS1/ITS2 sequencing. The median time between symptom onset and diagnosis was 22 days (range 6-131 days). All patients were treated with liposomal amphotericin b. 18.8% had a VL recurrence and were treated with miltefosine. Attributable mortality was 6.3%. Conclusions. VL due to L. infantum could determine periodical outbreaks, as the one described; thus it is important to include VL in the differential diagnosis of fever of unknown origin, even in low-endemic areas.


Asunto(s)
Brotes de Enfermedades , Leishmaniasis Visceral/epidemiología , Femenino , Humanos , Incidencia , Italia/epidemiología , Masculino
6.
J Med Chem ; 32(4): 774-8, 1989 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-2590277

RESUMEN

A group of potential alkylating agents have been synthesized that are structurally related to the oligopeptide antiviral antibiotic distamycin. All derivatives form complexes with native calf-thymus DNA but compounds 2, 3, and 6 give rise to covalent adducts. Cytostatic activity against both human and murine tumor cell lines in vitro is displayed by the new compounds. Compounds 3 and 4 are active on melphalan-resistant L1210 leukemia in mice.


Asunto(s)
ADN/metabolismo , Distamicinas , Neoplasias/tratamiento farmacológico , Pirroles , Alquilantes , Animales , Fenómenos Químicos , Química , Cromatografía Líquida de Alta Presión , Dicroismo Circular , Distamicinas/síntesis química , Distamicinas/metabolismo , Distamicinas/uso terapéutico , Humanos , Leucemia L1210/tratamiento farmacológico , Leucemia Experimental/tratamiento farmacológico , Ratones , Pirroles/síntesis química , Pirroles/metabolismo , Pirroles/uso terapéutico , Relación Estructura-Actividad , Células Tumorales Cultivadas
7.
J Med Microbiol ; 50(5): 407-414, 2001 May.
Artículo en Inglés | MEDLINE | ID: mdl-11339247

RESUMEN

Thirty-two related and 68 unrelated isolates of Clostridium difficile, isolated in different Italian hospitals since 1987, were analysed by PFGE and PCR-ribotyping to investigate their genetic relatedness. The isolates were classified into 28 groups by PFGE and 20 ribotypes by PCR-ribotyping. A single clone of C. difficile was recognised as the cause of three geographically and chronologically distant outbreaks. The correlation between PFGE and PCR-ribotyping results was good, with agreement for 77 (84%) of the 92 isolates typed by both methods. However, among sporadic isolates the discriminatory power of PFGE was more evident. Eight isolates that were untypable by PFGE could be analysed by PCR-ribotyping. The dendrograms generated showed that the genetic relatedness of the C. difficile isolates obtained by both techniques was comparable. The majority of the isolates in recent years appeared to be genetically unrelated to isolates from past infections. However, two clonal groups identified in all time periods had a common origin and this seems to indicate that they share some advantageous biological characteristics. The constant monitoring of C. difficile epidemiology will allow acquisition of further important data on this nosocomial pathogen.


Asunto(s)
Clostridioides difficile/genética , ARN Ribosómico 16S/genética , ARN Ribosómico 23S/genética , Clostridioides difficile/clasificación , ADN Bacteriano/genética , Electroforesis en Gel de Campo Pulsado , Filogenia , Reacción en Cadena de la Polimerasa , Especificidad de la Especie
8.
J Pharm Sci ; 73(6): 766-70, 1984 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-6588195

RESUMEN

The dimerization of doxorubicin, daunorubicin, and their 4-demethoxy, 4'-epi, and 4'-deoxy analogues was studied spectrophotometrically. Self-association was found to be influenced by buffer composition and ionic strength. Kd values were 1.3 X 10(4) and 2.3 X 10(4) M-1 for doxorubicin and daunorubicin, respectively, and ranged from 3.8 X 10(3) to 6.1 X 10(3) M-1 for the 4-demethoxy analogues. For 4'-epi- and 4'-deoxydoxorubicin, tetramerization has also been considered. On this basis, values of 2.0 X 10(4) and 2.2 X 10(4) M-1 were found, respectively, for the formation constant of the dimerization process. Stability of the dimeric species appears to be strongly influenced by substitution of the chromophore moiety.


Asunto(s)
Doxorrubicina , Química Farmacéutica , Daunorrubicina/análogos & derivados , Daunorrubicina/análisis , Doxorrubicina/análogos & derivados , Doxorrubicina/análisis , Epirrubicina , Idarrubicina , Soluciones , Espectrofotometría/métodos
9.
Int J Med Inform ; 73(4): 363-9, 2004 May.
Artículo en Inglés | MEDLINE | ID: mdl-15135755

RESUMEN

OBJECTIVES: Hospitals have started to migrate their paper-based records to computerized patient records (CPR). The majority of today's CPR systems are stationary, which means that physicians use a clinical workstation to access CPR information. But health care professionals need to request and enter information at different locations, for example, on their daily ward round. This suggests the use of mobile computers, enabling an ubiquitous access to needed data. Different studies show that health care professionals are reluctant to use poorly designed mobile CPR systems, as the work at the point of care is very time-pressured and hectic. To design a system with high acceptance, it is essential to obtain empirical insight into the work practices and context in which the mobile CPR system will be used. METHOD: We investigated the physicians' work with the patient record during their daily round. With the help of a compact notation method, the physicians' interaction with the information system was recorded in real time. Fourteen physicians from three different departments (internal medicine, surgery, and geriatrics) of a middle-sized Swiss hospital participated in our study. RESULTS: Physicians have clear access preferences when they interact with the patient record during their daily round. There exists a clear profile of access frequencies and patterns, respectively. As an example, approximately 50% of all patient record accesses concern information about medications, vital signs and lab test results. DISCUSSION/CONCLUSION: A CPR system which is designed to reflect the access frequencies and patterns should improve the efficiency of data entry and retrieval and thus result in a system with high acceptance among physicians in the demanding environment during hospital rounds.


Asunto(s)
Acceso a la Información , Sistemas de Registros Médicos Computarizados/organización & administración , Sistemas de Atención de Punto , Pautas de la Práctica en Medicina , Suiza
10.
J Int Med Res ; 18(3): 191-200, 1990.
Artículo en Inglés | MEDLINE | ID: mdl-2193834

RESUMEN

Ampicillin combined with the beta-lactamase inhibitor sulbactam was compared with ampicillin alone, cefoxitin and metronidazole against 569 clinical strains of anaerobic organisms. The strains included 289 species of Bacteroides, 160 strains of Clostridium and 120 strains of various species of Streptococcus/Peptostreptococus, Fusobacterium, Veillonella, Eubacterium, Bifidobacterium, Actinomyces and Propionibacterium. Sulbactam/ampicillin was as effective as cefoxitin and metronidazole against all anaerobic species tested, inhibiting more than 90% of strains at the breakpoints (16, 32 and 32 mg/l, respectively). Sulbactam/ampicillin was also significantly more active than ampicillin against strains of Bacteroides, the minimal inhibitory concentration being at least four-fold lower. In contrast, the activity of the combination did not differ from that of ampicillin alone against Fusobacterium species and Gram-positive rods and cocci.


Asunto(s)
Ampicilina/farmacología , Bacterias Anaerobias/efectos de los fármacos , Cefoxitina/farmacología , Metronidazol/farmacología , Sulbactam/farmacología , Bacterias Anaerobias/aislamiento & purificación , Interacciones Farmacológicas , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Humanos , Pruebas de Sensibilidad Microbiana , Estudios Multicéntricos como Asunto
11.
Ann Ist Super Sanita ; 15(1): 155-65, 1979.
Artículo en Italiano | MEDLINE | ID: mdl-553479

RESUMEN

The isolation and identification of anaerobic bacteria by biochemical tests take long time, so it is very useful the gas-chromatography to detect the volatile fatty acids produced from their metabolism. This technique can give rapidly a presumptive diagnosis of anaerobic infection so that it is possible to start immediately a correct antibiotic therapy. In this study we have examined many samples of pus and exudate, and the results have been compared with those obtained from the culture. We have found a good correlation between the detection by gas-chromatography of isobutyric and butyric acids and the isolation in the culture of anaerobic flora, and particularly of Bacteroides fragilis when the gas-chromatography detected isobutyric, butyric and succinic acids.


Asunto(s)
Infecciones Bacterianas/diagnóstico , Infecciones por Bacteroides/diagnóstico , Cromatografía de Gases , Anaerobiosis , Bacterias/metabolismo , Bacteroides/metabolismo , Butiratos/metabolismo , Ácidos Grasos Volátiles/metabolismo , Humanos
12.
Minerva Chir ; 53(1-2): 15-21, 1998.
Artículo en Italiano | MEDLINE | ID: mdl-9577131

RESUMEN

The authors report on their experience of 235 laparotomy operations and 125 laparoscopic operations performed on patients with right lower abdominal pain. Concerning each of these different approaches, the authors analyzed and compared preoperative diagnosis, anatomo-pathological findings, intraoperative and early post operative morbidity and hospital stay. The ratio of negative open-appendectomies was 24.1% (56 cases out of 233). The laparoscopic approach, performed on 88 cases of suspected appendicitis, allowed to document and to treat other pathologies, real causes of the lower right abdominal pain, in 42 cases (47.7%). The rate of conversion from laparoscopic appendectomy to open appendectomy was only 2.19% (2 cases out of 91). The morbidity rate of laparoscopic appendectomy was estimated at 6.5% (4.4% major complications, 2.2% minor complications). The morbidity rate of open appendectomy was estimated at 8.9% (0.4% major complications, 8.5% minor complications). Though the median postoperative stay, after laparotomy approach, was slightly longer (2.6 days versus 2.4 days), the difference was not statistically significant. Based on these results, the authors conclude that the laparoscopic approach should be reserved for fertile female patients, especially when the diagnosis of appendicitis is uncertain.


Asunto(s)
Apendicectomía/métodos , Apendicitis/cirugía , Laparoscopía , Dolor Abdominal/etiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Apendicitis/diagnóstico , Niño , Preescolar , Femenino , Humanos , Laparotomía , Tiempo de Internación , Masculino , Persona de Mediana Edad , Grabación en Video
13.
Biomed Tech (Berl) ; 43(5): 124-32, 1998 May.
Artículo en Alemán | MEDLINE | ID: mdl-9616991

RESUMEN

A commonly used method of investigating colour vision, that is, the ability of the human visual system to discriminate colours, is based on the use of isochromatic colour plates, such as those used in the Ishihara test. The present paper describes a new computer-based method of determining red/green colour vision deficiencies. The method involves the presentation of Ishihara colour plates on a computer monitor. It has been verified experimentally that, despite the differences between the spectral emission of the computer screen and the daylight reflected by the Ishihara plates, the method is capable of distinguishing between subjects with from those without colour vision deficiencies. For screening purposes, the use of a reduced number of plates is suggested. This suggestion makes use of nine instead of 14 plates, and the criterion of two incorrectly recognized plates to determine a colour vision deficiency.


Asunto(s)
Pruebas de Percepción de Colores/instrumentación , Defectos de la Visión Cromática/diagnóstico , Diagnóstico por Computador/instrumentación , Adulto , Defectos de la Visión Cromática/clasificación , Defectos de la Visión Cromática/prevención & control , Gráficos por Computador , Humanos , Masculino , Microcomputadores , Programas Informáticos , Selección Visual/instrumentación
14.
Biomed Tech (Berl) ; 43(11): 310-7, 1998 Nov.
Artículo en Alemán | MEDLINE | ID: mdl-9885417

RESUMEN

AIM: A computer-based approach to assess stereopsis for screening purposes is described. This approach is based on random-dot stereograms (RDS). METHOD: The TNO test is a common method to assess stereopsis based on red/green anaglyphs and the use of RDS. This technique was transferred to a computer-based platform. To investigate the validity of the computer-based approach, 25 subjects were tested with both the TNO test and the computer-based approach. RESULTS: With regard to the spectral emission of the monitor screen, accurate separation of red and green for RDS generation was not possible. However, adaptation of the RDS to the colour filters used permitted the best-possible separation. The resolution of the monitor required a viewing distance of 2 m. The results obtained showed no significant differences between the two methods. CONCLUSIONS: For the computer-based screening, RDS and anaglyphs can be employed. The influence of the spectral emission of the monitor screen and its resolution can be reduced by adapting the RDS colours to the filters used and modifying the viewing distance.


Asunto(s)
Percepción de Profundidad , Diagnóstico por Computador/instrumentación , Selección Visual/instrumentación , Diseño de Equipo , Humanos , Sensibilidad y Especificidad
15.
Biomed Tech (Berl) ; 42(3): 55-60, 1997 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-9181829

RESUMEN

Testing of visual acuity for distant vision can be computerized by using monitor screens to present optotypes. Because of the limited spatial resolution of conventional monitors, measurement of visual acuity for near vision is not possible. This paper describes a new computer-aided method for the measurement of both near and distant visual acuity. Our approach to the assessment of visual acuity for near vision is based on a recently developed liquid crystal display (a screen, LCD) measuring 10.5 mm x 15 mm. The LCD permits the presentation of optotypes for the measurement of visual acuity between 0.063 and 1.25 at a viewing distance of 40 cm (near/distant). The presentation of optotypes for the assessment of the acuity of distant vision uses a standard 17" monitor that permits visual acuity figures of between 0.032 and 1.6 to be assessed.


Asunto(s)
Diagnóstico por Computador/instrumentación , Pruebas de Visión/instrumentación , Agudeza Visual , Percepción de Distancia , Humanos , Microcomputadores , Programas Informáticos
16.
Biomed Tech (Berl) ; 46(4): 101-5, 2001 Apr.
Artículo en Alemán | MEDLINE | ID: mdl-11388036

RESUMEN

We describe a computer-aided self-test vision screener for testing near and far visual acuity. The device generates images separately for each eye on a LCD. Acuity can be measured in the range between 0.1 and 1.6 for any distance between 0.34 m and 6 m. In addition, it also enables testing for colour deficiency, phoria, stereopsis and contrast sensitivity. The device is fully automatic and enables self-testing of the above mentioned functions. Initial practical application in an industrial environment has demonstrated the practicability of the device.


Asunto(s)
Diagnóstico por Computador/instrumentación , Trastornos de la Visión/diagnóstico , Selección Visual/instrumentación , Diseño de Equipo , Humanos , Programas Informáticos , Agudeza Visual , Pruebas del Campo Visual/instrumentación
17.
Biomed Tech (Berl) ; 36(10): 253-9, 1991 Oct.
Artículo en Alemán | MEDLINE | ID: mdl-1768771

RESUMEN

Up till now, the simultaneous recording of the movements of the eyes, the movements of the head and the diameter of the pupil required the combined use of several apparatus. In this paper we present a new apparatus developed for the simultaneous recording of the movements of the eyes and of the head, and the diameter of the pupil. The apparatus consists of a portable frame (weight 215 g) a 19" rack containing electronics, and a PC for storing and analyzing the recorded data. In comparison with other systems providing similar measuring possibilities the present apparatus has the advantage of smaller dimensions and lower weight.


Asunto(s)
Movimientos Oculares/fisiología , Anteojos , Fijación Ocular/fisiología , Microcomputadores , Músculos del Cuello/fisiología , Reflejo Pupilar/fisiología , Procesamiento de Señales Asistido por Computador/instrumentación , Terminales de Computador , Humanos
18.
Biomed Tech (Berl) ; 46(3): 55-62, 2001 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-11324147

RESUMEN

We investigated the perception of brightness for red monochromatic laser light. For this purpose, a modified virtual retinal display (VRD) was constructed. The modification involved projecting the laser beam into the eye. In our VRD, the laser beam pivots in the nodal point of the eye (badal system). The displayed image therefore does not depend on the refractive state of the eye. Brightness perception was assessed by means of psychophysical experiments. The results of these experiments indicate that perception of brightness at 652 nm increases more rapidly with increasing physical stimulus than does the perception of white light (colour temperature 2'935 K). At a wavelength of 652 nm, an optical power of 79 nW is required to produce an image subtending 2 degrees of equal brightness, as is perceived with an image of about 2'900 cd/m2 subtending 2 degrees.


Asunto(s)
Percepción de Color/fisiología , Defectos de la Visión Cromática/diagnóstico , Sensibilidad de Contraste/fisiología , Retina/fisiopatología , Interfaz Usuario-Computador , Adulto , Defectos de la Visión Cromática/fisiopatología , Femenino , Humanos , Rayos Láser , Masculino , Estimulación Luminosa , Psicofísica , Valores de Referencia , Refracción Ocular/fisiología
19.
Biomed Tech (Berl) ; 48(6): 176-81, 2003 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12861658

RESUMEN

We compared two algorithms, which are used to assess the number of forward saccades in a reading task from records of eye movements. In one algorithm saccades are detected analysing the velocity of eye movements. The third derivate of eye position in time (jerk) is used in the second algorithm for the detection of saccades. Both algorithms were applied on the same set of data, recorded using 24 subjects reading a German text, which was presented on two different displays. Our subjects read the text at a mean reading speed of 258.5 word/min. Both algorithms were found to produce a similar rate of artefacts in the number of detected saccades (2.5%), provided the threshold for detection (velocity or jerk) is set at an appropriate level and the same level of threshold is applied to all data. In both algorithms, the rate of artefacts increases with increasing distance of the threshold from its optimum. Inter-individual variation of the rate of artefacts increases more pronounced in the algorithm based on jerks. Eye blinks were identified as a major source of artefacts. A remedy is proposed, by means of which the rate of artefacts can be reduced.


Asunto(s)
Algoritmos , Electrooculografía/instrumentación , Lectura , Movimientos Sacádicos , Procesamiento de Señales Asistido por Computador/instrumentación , Adulto , Artefactos , Parpadeo , Presentación de Datos , Femenino , Humanos , Masculino , Cómputos Matemáticos , Reproducibilidad de los Resultados
20.
Ann Ig ; 1(1-2): 125-32, 1989.
Artículo en Italiano | MEDLINE | ID: mdl-2483059

RESUMEN

During a period of four consecutive years (1984-1988) more than one thousand of serum samples were obtained from different "at risk" categories of patients with the aim to investigate on the prevalence of anti-HIV antibodies in these populations. Also HIV antigen and HBV markers were investigated in the same people. Some of them were followed up to monitor the various HIV markers and to cultivate biological material from symptomatic cases. All serological investigations were carried out by means of ELISA methods and the Western Blot technique, to confirm positive results. Data obtained from this study showed that: 1. in our area anti-HIV positive people prevail among intravenous drug addicts (IVDA) (42-48%) in contrast to 3.3% of homosexuals, and in 14-16% of subjects or patients declaring themselves "at risk" without stating what of risk it is. 2. HIV antigen was demonstrated in 5% of symptomatic IVDA patients but only in two cases of anti-HIV negative people. 3. HBV markers were found in all categories examined, prevailing in IVDA subjects (72%). 4. Five percent only of anti-HIV negative people followed up through 2-36 mo. seroconverted while only 39.7% of anti-HIV positive people showed an HIV markers variation (increase, decrease or disappearance) in different periods of time (1-8 mo.). 5. Opportunistic infections were observed in 50% of symptomatic patients.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Seroprevalencia de VIH , Adolescente , Adulto , Femenino , Estudios de Seguimiento , Infecciones por VIH/complicaciones , Infecciones por VIH/epidemiología , Seropositividad para VIH , Hepatitis B/complicaciones , Hepatitis B/epidemiología , Humanos , Italia/epidemiología , Masculino , Persona de Mediana Edad , Infecciones Oportunistas/epidemiología , Infecciones Oportunistas/etiología , Estudios Prospectivos , Factores de Riesgo
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