Background elimination and interferometric capability in optical coherence tomography by a nonlinear optical gating based on type-II second-harmonic generation.

A novel method that uses nonlinear optical gating to control background illumination in optical coherence tomography is presented. With this method, the user can adjust the amount of undesired backscattering or eliminate it completely, which enables dark-field measurements. The interferometric capability of the method in a nonlinear optical regime is demonstrated with the coupling of three overlapping input waves to yield Fizeau fringes. The measurement of a 265 nm step is performed to validate this method, which was originally conceived for 3D MEMS characterization.

Three-dimensional Fourier transform evaluation of sequences of spatially and temporally modulated speckle interferograms.

Phase evaluation methods based on the 2D spatial Fourier transform of a speckle interferogram with spatial carrier usually assume that the Fourier spectrum of the interferogram has a trimodal distribution, i. e. that the side lobes corresponding to the interferential terms do not overlap the other two spectral terms, which are related to the intensity of the object and reference beams, respectively. Otherwise, part of the spectrum of the object beam is inside the inverse-transform window of the selected interference lobe and induces an error in the resultant phase map. We present a technique for the acquisition and processing of speckle interferogram sequences that separates the interference lobes from the other spectral terms when the aforementioned assumption does not apply and regardless of the temporal bandwidth of the phase signal. It requires the recording of a sequence of interferograms with spatial and temporal carriers, and their processing with a 3D Fourier transform. In the resultant 3D spectrum, the spatial and temporal carriers separate the conjugate interferential terms from each other and from the term related to the object beam. Experimental corroboration is provided through the measurement of the amplitude of surface acoustic waves in plates with a double-pulsed TV holography setup. The results obtained with the proposed method are compared to those obtained with the processing of individual interferograms with the regular spatial-carrier 2D Fourier transform method.

Implementación de un programa de mejoramiento de la seguridad de los pacientes: resultados preliminares / Implementation of a program of improvement of the security of the patients: preliminary results

Tradicionalmente, el error ha servido para aprender lo que no había que hacer y lo que no era verdad. Luego se sumó la reacción de castigar al responsable del error suponiendo que éste era producto de la incapacidad o irresponsabilidad individual. La búsqueda, explícita o no, del "culpable" ha promovido mayor temor en los profesionales de la salud y generado una creciente tendencia a ocultar los errores. Desde 2001, la Academia Nacional de Medicina, a través de su Centro de Investigaciones Epidemiológicas, desarrolló e implementó un programa para el mejoramiento de la seguridad en la atención de los pacientes, en cuatro instituciones sanitarias de nuestro país de diferentes características. El propósito del programa es: "diseñar, validar y evaluar metodologías que permitieran identificar errores, casi errores y eventos adversos; analizar el mecanismo de su producción y contribuir a señalar los procesos correctivos". El mismo está organizado en cuatro componentes: a) cultura organizacional para la seguridad del paciente; b) sistemas de información para la vigilancia del error durante el proceso de atención, c) mejoramiento continuo de la seguridad del paciente y d) gestión de conocimiento.

Enhancing the sensitivity to small phase changes in double-exposure stroboscopic television holography.

We present a new technique for enhancing the sensitivity of double-exposure stroboscopic television holography (TVH) to detect and measure vibrations of small amplitude. The technique is based in the modulation of the phase of the reference beam in synchronism with the vibration of the measurand and derives from a former technique that we originally contrived for phase evaluation. We propose two variants, characterized by the demodulation process used to generate the secondary correlograms, with different behaviors in terms of the sensitivity to the sign of the measurand and of the ease in detecting the presence and shape of the vibration. We have implemented this new technique in an electronic speckle-pattern interferometer and compared its performance with standard TVH techniques; vibrations with amplitudes as small as 8 nm have been observed with this setup.

Reliability of applanation tonometry readings obtained with a disposable latex cap.

BACKGROUND: To verify the accuracy of applanation tonometry through disposable latex caps used to prevent transmission of infectious diseases. METHODS: Tonometry was performed in 80 patients. Each patient underwent two intraocular pressure (IOP) measurements with and without the latex. In group A patients tonometry was performed first without the cap; in group B tonometry was performed first with the cap. Each group was also divided into patients with IOP, >/=20 mm Hg (A1; B1) and patients with IOP <20 mm Hg (A2; B2). RESULTS: The mean difference of tonometry readings was equal to -0.36 +/- 1. 62 mm Hg in group A, -0.03 +/- 1.77 mm Hg in group A1, -0.61 +/- 1. 45 mm Hg in group A2, 0.23 +/- 1.44 in group B, 0.64 +/- 1.41 mm Hg in group B1, 0.05 +/- 1.42 in group B2. A statistically significant correlation was found in group A, in group A2, B, B1 and B2; a less significant correlation was found in group A1. CONCLUSIONS: The use of the latex caps does not alter the reliability of tonometry readings as long as the cap is applied tightly. Measurement variation in our study is comparable to published data on applanation tonometry.

Primary anastomosis in the treatment of acute disease of the unprepared left colon.

Between June 1, 1990 and December 31, 1996, 58 consecutive patients with unprepared colons were urgently explored for nontraumatic disease with intent to proceed with primary left-sided colonic anastomosis. Unprotected anastomoses were not attempted in 15 patients. The causes of exclusion included preoperative and intraoperative shock in three patients, and three patients were on long-term high-dose steroids, four had gross fecal contamination of the peritoneal cavity, four had large pelvic abscesses, and one had ischemic colitis. All 43 patients undergoing anastomosis without protective colostomy had stapled anastomoses. Indications included complicated diverticular disease in 32 cases. There were nine cases of obstruction from colorectal carcinoma and one obstruction due to sigmoid volvulus. There was one case of perforation from pseudomembranous enterocolitis. The most common complications were: atelectasis in nine cases, wound infection in two cases, and prolonged ileus in two cases. Pelvic abscess occurred in one case. There was one wound dehiscence. There was one anastomotic dehiscence, and there was no mortality. Operative time averaged 85 minutes and hospital length of stay 9.7 days. Primary anastomosis of the unprepared left colon is safe in most urgent and emergent situations, thus avoiding the significant morbidity and cost of colostomy closure.

Treatment of uncomplicated cases of rhegmatogenous retinal detachment with an expanding gas bubble.

We reviewed 55 consecutive cases of rhegmatogenous retinal detachment treated with pneumatic retinopexy as a primary procedure and followed up for a minimum of 1 year. 40 eyes were phakic, 11 aphakic and 4 pseudophakic. 0.6 ml of sulfur hexafluoride were injected into 42 eyes, while 0.3 ml of perfluoropropane were introduced into 13. Transconjunctival cryotherapy was performed in 51 eyes, while light coagulation was used as retinopexy after the retina was reattached in the remaining 4 cases. Of the 55 eyes undergoing treatment, 46 (83.6%) retinas were reattached with one operation. The benefits, complications and disadvantages of the procedure are reported.

Have changing treatment patterns affected outcome for operable breast cancer? Ten-year follow-up in 1288 patients, 1965 to 1978.

From 1965 to 1978, 1288 patients with primary operable breast cancer were treated by the senior author, using extended radical (ERM), radical (RM), and modified radical (MRM) mastectomy operations exclusively. Results were analyzed for trends in overall and disease-free survival, and patterns of local and distant relapse, the years 1965 to 1970 versus 1971 to 1974 versus 1975 to 1978. Significant changes (p less than 0.00001) from 1965 to 1978 included progressively earlier stage of disease, less frequent use of RM and ERM, a decline in the use of postoperative radiotherapy, and the introduction in 1975 of multidrug adjuvant chemotherapy. Ten-year disease-free survival rates improved significantly for all patients (by 11%, p = 0.00004) and for node-negative (by 12%, p = 0.0024), node-positive (by 8%, p = 0.012), clinical stage II (by 15%, p = 0.0022), and pathologic stage II (by 12%, p = 0.016) disease. Ten-year local recurrence for all patients was 3% (local only) and 2% (local with distant metastasis), and survival from date of recurrence for all patients failing treatment increased two times (p less than 0.0001) for patients treated most recently. As the primary surgical treatment of breast cancer continues to become more moderate, the promise of systemic adjuvant therapies can be realized only with continued emphasis on earlier diagnosis and maximal local control of disease.

Emergency colectomy for cytomegalovirus ileocolitis in patients with the acquired immune deficiency syndrome.

The charts of all patients with the acquired immune deficiency syndrome (AIDS) who underwent emergency intra-abdominal surgery between January 1981 and July 1987 were reviewed. Eleven AIDS patients underwent 13 emergency laparotomies. Seven of these patients (64 percent) had cytomegalovirus (CMV) ileocolitis as the pathologic process requiring emergent surgical intervention. Four patients had hemorrhagic CMV proctocolitis and three had perforations of CMV ulcers of the ileum or rectosigmoid. The operations performed included three subtotal colectomies, two segmental resections, and two diverting stomas. The postoperative mortality rate in the CMV group was 28 percent at one day, 71 percent at one month, and 86 percent at six months. Furthermore, CMV ileocolonic pathology was directly responsible for 70 percent of the deaths in AIDS patients who underwent emergent exploratory laparotomy.