Impact of interface roughness on the performance of broadband blackbody absorber based on dielectric-metal film multilayers.

We report on factors affecting the performance of a broadband, mid-IR absorber based on multiple, alternating dielectric / metal layers. In particular, we investigate the effect of interface roughness. Atomic layer deposition produces both a dramatic suppression of the interface roughness and a significant increase in the optical absorption as compared to devices fabricated using a conventional thermal evaporation source.

Analysis of reflective Mach-Zehnder interferometry for electro-optic characterization of poled polymer films in multilayer structures.

We consider the Mach-Zehnder interferometer (MZI) method that specifically uses a poled organic thin film as one of the reflective mirrors in order to characterize the two independent electro-optic tensor elements r(13) and r(33). We discuss both a simple analysis based on a three-layer structure and a rigorous method including multiple reflection effects in a multilayer structure. In doing so, we find that the simple analysis of the reflective MZI method yields identical results to the reflection ellipsometric method (simple Teng-Man method), first introduced by Teng and Man as well as Shildkraut in 1990, when the ratio of r(13) to r(33) obtained from the MZI method is used in the analysis of the simple Teng-Man method.

Broadband and mid-infrared absorber based on dielectric-thin metal film multilayers.

We propose a periodic multilayer structure of dielectric and metal interlayers to achieve a near-perfect broadband absorber of mid-infrared radiation. We examine the influence of four factors on its performance: (1) the interlayer metal conductance, (2) the number of dielectric layers, (3) a nanopatterned antireflective layer, and (4) a reflective metallic bottom layer for backreflection. Absorption characteristics greater than 99% of the 300 K and 500 K blackbody spectra are found for the optimized structures.

Closed-form Maker fringe formulas for poled polymer thin films in multilayer structures.

We report new closed-form expressions for Maker fringes of anisotropic and absorbing poled polymer thin films in multilayer structures that include back reflections of both fundamental and second-harmonic waves. The expressions, based on boundary conditions at each interface, can be applied to multilayer structures containing a buffer and a transparent conducting oxide layer, which might enhance multiple reflections of fundamental and second-harmonic waves inside a nonlinear thin film layer. This formulation facilitates Maker fringe analysis for a sample containing additional multilayer structures on either side of a poled polymer thin film.

Gallbladder wall thickening in patients with acute hepatitis.

Background: Gallbladder wall thickening (GWT) is often observed in patients with acute hepatitis (AH). However, little is known regarding the relationship between AH and GWT. We analyzed the characteristics of GWT in patients with AH.

Thickening of the gastric wall on transabdominal sonography: a sign of gastric cancer.

Purpose: To determine the value of a thickened gastric wall detected during transabdominal sonography (TAS) in the diagnosis of gastric cancer.

Method: This prospective study comprised 312 patients who underwent both TAS and endoscopy. Transverse TAS scanning was performed using a 3.

An adequate level of training for technical competence in screening and diagnostic colonoscopy: a prospective multicenter evaluation of the learning curve.

Background: Various training programs in colonoscopy recommend that trainees should perform at least 100 to 200 procedures to be considered technically competent at diagnostic colonoscopy.

Objective: Our purpose was to determine the adequate level of training for technical competence in screening and diagnostic colonoscopy.

Design: A prospective multicenter trial.

Effect of propranolol on portal pressure and systemic hemodynamics in patients with liver cirrhosis and portal hypertension: a prospective study.

Background/aims: Propranolol can prevent variceal bleeding by ameliorating portal hypertension. We conducted this study to determine the effect of propranolol on portal hypertension and the optimal required dose in Korean cirrhotic patients.

Methods: This study prospectively evaluated 50 patients with cirrhosis who exhibited variceal bleeding.

Clinicopathologic characteristics and malignant potential of colorectal flat neoplasia compared with that of polypoid neoplasia.

Purpose: Because of their potential for malignancy, flat colorectal neoplasias are a current topic of debate. This study was designed to investigate the clinicopathologic features of flat neoplasia and to compare them with those of polypoid neoplasia, as well as to identify the determinants of malignant transformation of both flat and polypoid colorectal neoplasia.

Methods: A prospective, cross-sectional study of 3,360 patients diagnosed with adenomas via total colonoscopy and polypectomy was performed at 11 tertiary medical centers between July 2003 and July 2004.

Damping index of Doppler hepatic vein waveform to assess the severity of portal hypertension and response to propranolol in liver cirrhosis: a prospective nonrandomized study.

Background And Aims: Alterations in the Doppler hepatic vein (HV) waveform are associated with cirrhosis and portal hypertension. We prospectively evaluated the correlation between the extent of abnormal Doppler HV waveforms expressed as damping index (DI) and the hepatic venous pressure gradient (HVPG) and response to propranolol in patients with cirrhosis.

Material And Methods: In 76 patients with cirrhosis (69 men and seven women), both DI of Doppler HV waveform and HVPG were measured, and the relationship between them was analysed.

[Inhibitory effect of angiotensin blockade on hepatic fibrosis in common bile duct-ligated rats].

Backgrounds And Aims: Angiotensin receptors are found on hepatic stellate cells, which participate in hepatic fibrosis. Therefore, it is presumed that angiotensin has a role in hepatic fibrosis. The aim of this study was to evaluate the effects of angiotensin blockade on inhibition of hepatic fibrosis in cirrhotic rat model.

[Interequipment variability of Doppler ultrasonographic indices in patients with liver cirrhosis].

Backgrounds/aims: Doppler ultrasongraphy is used to evaluate hemodynamic alternations in patients with liver cirrhosis. Purpose of this study was to determine the interequipment variability of Doppler indices in portal and splenic vein in cirrhosis.

Methods: Blood velocity, diameter, flow and congestive index in portal and splenic vein were measured by Doppler ultrasonography in 30 patients with cirrhosis using two different machines.

Effectiveness of walking exercise as a bowel preparation for colonoscopy: a randomized controlled trial.

Objectives: This prospective study was conducted to assess the effect of walking exercise on bowel cleansing before colonoscopy and to define a patient subgroup that would benefit from walking exercise.

Methods: A total of 383 outpatients were randomized into two groups (G1 [n = 196]; walking exercise, G2 [n = 187]; nonexercise). Those randomized to G1 were instructed to drink 250 mL of polyethylene glycol (PEG) solution and then walk at least for 5 min at intervals of 10 min whereas those randomized to G2 were instructed to drink and then take rest in a waiting room until the entire 2.

Captopril reduces portal pressure effectively in portal hypertensive patients with low portal venous velocity.

Background: The effect of an angiotensin II blockade in lowering the portal pressure in patients with liver cirrhosis and portal hypertension is controversial. This prospective study was undertaken to evaluate the portal hypotensive effect of captopril compared to that of propranolol, and to determine the factors that contribute to a successful reduction in the portal pressure after longterm captopril administration in patients with liver cirrhosis.

Methods: The hepatic venous pressure gradient (HVPG) and portal venous velocity (PVV) were measured both before and 3 months after initiation of the administration of captopril (n = 29) or propranolol (n = 29) in cirrhotic patients with a variceal bleeding episode.