Efficient energy transfer from InGaN quantum wells to Ag nanoparticles.

Nonradiative energy transfer from an InGaN quantum well to Ag nanoparticles is unambiguously demonstrated by the time-resolved photoluminescence. The distance dependence of the energy transfer rate is found to be proportional to 1/d(3), in good agreement with the prediction of the dipole interaction calculated from the Joule losses in acceptors. The maximum energy-transfer efficiency of this energy transfer system can be as high as 83%.

Fluorescence signals of quantum dots influenced by spatially controlled array structures.

Fluorescence signals of quantum dots (QDs) influenced by different array structures of gold-coated silicon nanorods (SiNRs) were investigated via experimental observations and two-dimensional (2D) finite element method (FEM) simulations. On the densest gold-coated SiNRs array structure, the highest QD fluorescence quenching rates were observed and on the sparsest array structure, the highest QD fluorescence enhancement rates were observed. By developing a new technique which obtains the optical image of the array structures without losing information about the QD locations, we were able to further investigate how the QD fluorescence is influenced by spatially controlled array structures.

Cellular automaton simulation of pedestrian counter flow with different walk velocities.

This paper presents a cellular automaton model without step back for pedestrian dynamics considering the human behaviors which can make judgments in some complex situations. This model can simulate pedestrian movement with different walk velocities through update at different time-step intervals. Two kinds of boundary conditions including periodic and open boundary for pedestrian counter flow are considered, and their dynamical characteristics are discussed. Simulation results show that for periodic boundary condition there are three phases of pedestrian patterns, i.e., freely moving phase, lane formation phase, and perfectly stopped phase at some certain total density ranges. In the stage of lane formation, the phenomenon that pedestrians exceed those with lower walk velocity through a narrow walkway can be found. For open boundary condition, at some certain entrance densities, there are two steady states of pedestrian patterns; but the first is metastable. Spontaneous fluctuations can break the first steady state, i.e., freely moving phase, and run into the second steady state, i.e., perfectly stopped phase.

Hepatocellular carcinoma after renal transplantation: the long-term impact of cirrhosis on chronic hepatitis B virus infection.

Hepatocellular carcinoma (HCC) is the most common posttransplantation malignancy in hepatitis B virus (HBV) endemic areas. The aim of this study was to review the significant effect of liver cirrhosis on the outcome of renal allograft recipients with chronic hepatitis B. We performed a retrograde analysis of the clinical presentations of 66 hepatitis B surface antigen-positive kidney allograft recipients during the past 25 years with a mean follow-up of 76 months. Seven patients were diagnosed with HCC. The patients were subgrouped into cirrhotic versus noncirrhotic liver cohorts. Among renal allograft recipients with HBV infection, patients with cirrhotic livers had a higher risk of HCC (P = .003) and mortality (P = .025) than those with a noncirrhotic liver. The outcome was poor among the cirrhotic liver group. Pretransplantation liver biopsy may be indicated for the recipient candidate with HBV infection. Liver cirrhosis may be an exclusion criterion for the renal transplant waiting list due to the high incidence of HCC and the poor patient survival.

Subchondral insufficiency fracture of the femoral head.

Subchondral insufficiency fracture of the femoral head is a recently recognised entity. There are a few cases reported in Japanese and Caucasian patients but none in the Hong Kong population. The condition typically occurs in elderly females with osteoporosis. Acute hip pain is the usual presentation. The patient may have concomitant insufficiency fractures elsewhere. Magnetic resonance imaging is usually required to make the diagnosis. The prognosis of the condition is unknown. Reported complications include rapid collapse of the femoral head and coxopathy. Joint replacement should be considered if conservative management fails.

Increased risk of pulmonary tuberculosis in patients with gastroesophageal reflux disease.

BACKGROUND: Previous studies have suggested a close correlation between gastroesophageal reflux disease (GERD) and various respiratory disorders. However, the association between GERD and tuberculosis (TB) remains unexplored. METHODS: Using data retrieved from Taiwan's National Health Insurance Research Database from 2000 to 2009, this longitudinal nationwide cohort study included a total of 63,930 patients with GERD and controls matched by age, sex and comorbidities. Risk factors associated with the development of pulmonary TB (PTB) were investigated. RESULTS: Active PTB was documented in 65 (0.20%) patients with GERD and 41 (0.13%) matched cohorts within 1 year of GERD diagnosis. The incidence rate of PTB in the GERD group and the matched cohort was respectively 24.1 and 15.2 cases per 10,000 person-years. In multivariate analysis, GERD was an independent risk factor for PTB (adjusted HR 1.63, 95%CI 1.10-2.40, P = 0.015). Among patients with GERD, independent predictors for PTB included older age, male sex, chronic obstructive pulmonary disease, asthma and exposure to proton pump inhibitors (PPIs). CONCLUSION: Patients with GERD have a significantly increased risk of PTB within 1 year of GERD diagnosis. Exposure to PPIs is an independent predictor for PTB among patients with GERD.

Long-term risk of tuberculosis in haematopoietic stem cell transplant recipients: a 10-year nationwide study.

BACKGROUND: Tuberculosis (TB) is a serious problem for patients undergoing haematopoietic stem cell transplantation (HSCT) in TB-endemic areas; however, data on these patients are limited. METHODS: We obtained data on 2040 HSCT recipients from the Registry of Catastrophic Illness in Taiwan from 1997 to 2006. We also obtained data on age-, sex- and enrolment date-matched controls from the Longitudinal Health Insurance Database. The cumulative incidence of active TB in HSCT recipients and controls and risk factors for TB were analysed. RESULTS: Among 2040 HSCT recipients identified, 39 (1.9%) had newly diagnosed TB. The incidence rate was 688 per 100 000 person-years. The 10-year cumulative TB incidence was respectively 3.52% and 0.38% in HSCT recipients and controls (P < 0.001). HSCT was an independent risk factor for TB compared with matched controls. Among post-HSCT patients, independent risk factors for TB included age ⩾18 years and allogeneic recipients with graft-versus-host disease (GVHD). Post-HSCT patients with subsequent TB had a higher mortality rate than those without TB (P < 0.001). CONCLUSION: HSCT is associated with an increased risk of TB in endemic regions. Older age and development of chronic GVHD are independent predictors of late onset active TB in HSCT recipients.

A theoretical study of cylindrical ultrasound transducers for intracavitary hyperthermia.

PURPOSE: The purpose of this paper was to examine the heating patterns and penetration depth when a cylindrical ultrasound transducer is employed for intracavitary hyperthermia treatments. METHODS AND MATERIALS: The present study employs a simulation program based on a simplified power deposition model for infinitely long cylindrical ultrasound transducers. The ultrasound power in the tissue is assumed to be exponentially attenuated according to the penetration depth of the ultrasound beam, and a uniform attenuation for the entire treatment region is also assumed. The distribution of specific absorption rate (SAR) ratio (the ratio of SAR for a point within the tissue to that for a specific point on the cavity surface) is used to determine the heating pattern for a set of given parameters. The parameters considered are the ultrasound attenuation in the tissue, the cavity size, and the transducer eccentricity. RESULTS: Simulation results show that the ultrasound attenuation in the tissue, the cavity size, and the transducer eccentricity are the most influential parameters for the distribution of SAR ratio. A low frequency transducer located in a large cavity can produce a much better penetration. The cavity size is the major parameter affecting the penetration depth for a small cavity size, such as interstitial hyperthermia. The heating pattern can also be dramatically changed by the transducer eccentricity and radiating sector. In addition, for a finite length of cylindrical transducer, lower SAR ratio appears in the regions near the applicator's edges. CONCLUSION: The distribution of SAR ratio indicates the relationship between the treatable region and the parameters if an appropriate threshold of SAR ratio is taken. The findings of the present study comprehend whether or not a tumor is treatable, as well as select the optimal driving frequency, the appropriate cavity size, and the eccentricity of a cylindrical transducer for a specific treatment.

Negative captopril renography on patients with renin mediated hypertension due to page kidney and reninoma.

Through a mechanism similar to renal artery stenosis, patients with reninoma and page kidney also suffered from renin mediated hypertension. Captopril renograms performed on our patients with the latter two conditions, however, did not yield diagnostic findings. Therefore, equivocal or negative captopril renography cannot serve to rule out conditions with elevated renin other than renal artery stenosis.

Important role of cardiac spect imaging in patients undergoing percutaneous transluminal coronary angioplasty.

OBJECTIVE: To examine the utilization and contribution of cardiac perfusion scans to patients undergoing percutaneous transluminal coronary angioplasty. METHODS: From July 1996 to January 1998, 34 patients underwent percutaneous transluminal coronary angioplasty and cardiac SPECT imaging was studied. Twenty-five patients had pre-procedure SPECT scans. The agreement between angioplasty strategies and SPECT findings of ischemia and hypokinesia was examined. RESULTS: When radionuclide imaging was performed before revascularization procedures, 84% of the patients had intervention strategies guided by scan findings. Perfusion scan findings including extent and severity of ischemia, degree of hypokinesia directed the selection of target vessel for angioplasty in the patient subgroup with multi-vessel disease. Post-angioplasty radionuclide cardiac scans were performed only on symptomatic patients, demonstrating ischemia and hypokinesia in most of them, conceivably reflected the selection bias. CONCLUSION: We recommend routine pre- and post-angioplasty radionuclide imaging with multigated scans for wall motion assessment for all patients receiving coronary intervention.

Acute suppurative thyroiditis due to foreign body-induced retropharyngeal abscess presented as thyrotoxicosis.

Acute suppurative thyroiditis is an uncommon condition. Most patients have preexisting oropharyngeal fistulae. Penetrating oropharyngeal injuries resulting from swallowed foreign bodies provide an acquired channel of infection spreading into the relatively resistant thyroid gland. The authors describe a patient with infective thyroiditis complicating retropharyngeal abscess caused by a chicken bone that perforated the upper esophagus. Transient thyrotoxicosis complicating acute suppurative thyroiditis is very rare. Pertechnetate and Ga-67 scans confirmed extensive inflammation of the thyroid gland and the release of hormones as the cause, as distinct from concurrent Graves' disease. Awareness of this unusual complication is important to avoid inappropriate treatment for hyperthyroid disease.

Hepatocellular carcinoma with extrahepatic collateral arterial supply.

Haepatocellular carcinoma (HCC) is the most common primary liver malignancy, representing the fifth most common cancer in the world. Without treatment, the median survival of HCC patients has been reported to be 8 weeks from symptomatic presentation. Transarterial chemoembolisation is widely used to manage unresectable HCCs. However, when a tumour is large or locates near the liver capsule, it may receive supplies from vessels other than hepatic arteries. In this paper, we discuss the anatomy of possible extrahepatic collateral arterial supplies of HCCs.

Foreign body ingestion: comparison of diagnostic accuracy of computed tomography versus endoscopy.

PURPOSE: To investigate and compare the sensitivity and specificity of computed tomography and of endoscopy, as diagnostic tests for foreign body ingestion. MATERIALS AND METHODS: Over a two-year period, Asian patients with suspected foreign body ingestion were studied. The clinical findings, computed tomography images, endoscopic results, treatment and outcomes were prospectively analysed. RESULTS: Over the study period, 193 patients were admitted for foreign body ingestion, complaining of a persistent foreign body sensation in the neck. The sensitivity and specificity of computed tomography were 78 and 96 per cent, respectively; the positive predictive value was 75 per cent and the negative predictive value 97 per cent. The diagnostic accuracy of computed tomography was 94 per cent. CONCLUSION: Our study showed that computed tomography had high negative predictive value and accuracy in the diagnosis of foreign body ingestion. It was useful if endoscopy showed negative findings but the patient still had persistent symptoms of foreign body ingestion.

Decrease in stereoacuity in the seventh decade of life.

We measured stereoacuity in 41 subjects with normal Snellen acuity in each eye, and normal ocular health. Patients were measured in each of the age ranges 21-28, 41-49, 51-59 and 60-70 years. Stereoacuity was reduced from about 16 sec arc for the three younger groups to about 27 sec arc for the older subjects. Since stereopsis has a cortical neural substrate, these data suggest that there may be cortical changes affecting the interaction of information from the two eyes with advancing age, but whether these changes result from loss of contrast sensitivity, instability of ocular alignment or binocular stress, all of which have been reported in elderly subjects, is not known.

A new stereotest: the double two rod test.

A new stereoacuity test, the double two rod test, uses a two-alternative forced-choice (2AFC) paradigm. The subject's task is to state which pair of rods, the left or the right, contains depth information. The test gives repeatable results; comparison between the depth threshold measured binocularly and monocularly suggests that monocular cues, if present, provide only poor depth information, compared to the depth information arising from binocular disparity. As part of an investigation of stereoacuity and ageing, we tested stereoacuity as a function of viewing time and the number of comparisons made between the two pairs of rods. Stereoacuity was significantly reduced for viewing times less than 3 s while longer viewing times did not improve stereoacuity. The number of comparisons made between the two pairs of rods had no effect on stereoacuity.

[Use of intraspinal narcotics in obstetric anesthesia and analgesia].

The use of intraspinal narcotics has attracted great interest worldwide, particularly in the discipline of obstetric anesthesia. As the advent of spinal and epidural local anesthetics dramatically effected the anesthetic management of labor, delivery and obstetric surgery, likewise spinally administered opioids are emerging as safe and very effective methods of relieving post-cesarean section pain, improving labor and cesarean section analgesia in combination with local anesthetics, and injected alone in the subarachnoid space for the management of labor itself. Though intraspinal narcotic analgesia is associated with a number of side effects, with proper knowledge these adverse reactions are wither preventable or can be greatly reduced. Compared to the benefits of nearly complete pain relief in the intrapartum and postpartum periods, the price paid in terms of these side effects in minimal. The review was based on a computer-assisted search for articles published after 1975.

Combined para-aminosalicylic acid and dietary therapy in long-term control of hypercholesterolemia and hypertriglyceridemia (Types IIa and IIb hyperlipoproteinemia).

The hypolipidemic effect of PAS-C-diet treatment was studied in 63 patients with Types IIa and IIb hyperlipoproteinemia for 6-36 months. Serum lipids and body weights of all patients were stabilized by a low cholesterol-saturated fat-refined carbohydrate diet before the initiation of an eight-week placebo-drug single-blind crossover study. During the placebo period the plasma lipids levels, mean +/- SD: cholesterol 355 +/- 63.5 mg%, triglyceride 141 +/- 68.7 mg%, and LDL-cholesterol 279 +/- 56.8 mg% were lowered to 274 +/- 53.1 mg+, 98 +/- 40.6 mg%, and 209 +/- 52.9 mg%, respectively (P less than 0.001 in each instance), with 7.5-11.0 grams of PAS-C/day given in one to three divided doses. In ten patients who have completed three years of treatment similar results were obtained. They showed no tendency to develop drug tolerance. Eight had watery diarrhea during the initial period which promptly subsided with interruption of drug therapy. Reintroduction of PAS-C in smaller dose (4.5 g/day) with gradual increment to effective dosage level was tolerated by all. No hematologic, hepatic, and ophthalmologic abnormalities were demonstrated by periodic monitoring. The hypoplipidemic effect of the drug was found to be diminished by alcohol and caloric excess.