Enhanced optical transmission by light coaxing: mechanism of the TEM-mode excitation.

This paper presents a theoretical study showing the mechanism of light transmission through opaque metallic films perforated with nanocoaxial apertures thanks to the excitation of their cutoff-free TEM (Transverse ElectroMagnetic) guided mode. Full three-dimensional Finite Difference Time Domain (3D-FDTD) together with a Body-Of-Revolution FDTD simulation results are presented and discussed in order to optimize this extraordinary transmission. Very promising findings are pointed out opening the path to the design of new devices for both nano-optic and photovoltaic applications.

Implementation of dispersion models in the split-field-finite-difference-time-domain algorithm for the study of metallic periodic structures at oblique incidence.

We extend here the finite-difference-time-domain (FDTD) algorithm working in oblique incidence to dispersive media. The split-field method (SFM) is used and adapted for taking into account the metal dispersion. The additional equations to the FDTD algorithm are given. Instead of the 24 field components usually used in the SFM, 38 and 112 field components are needed to implement the cases of Drude and Drude-Lorentz dispersion models, respectively. Some tests are presented to validate our code as long as the angle of incidence is lower than 76 degrees in addition to an application dealing with enhanced transmission and showing original results.

Asthma is not a common cause of severe chronic respiratory failure in non-smokers: ALOT study.

BACKGROUND: Little is known about the long-term natural history of asthma and the long-term clinical and functional consequences in non-smoking patients. From a functional point of view, non-smoking asthmatic patients may have a significantly greater decline in forced expiratory volume in one second (FEV1) compared with non-asthmatic subjects and may develop chronic irreversible (fixed) airflow limitation. This has been related to the physiological consequences of chronic airway inflammation causing airway remodeling. However these lesions are all potentially reversible and there is little radiological evidence indicating lung destruction (pulmonary emphysema), which is potentially irreversible, in non-smoking asthmatics. Severe chronic respiratory failure is the major cause of mortality in patients with severe chronic lung diseases. Domiciliary long-term oxygen therapy (LTOT) is an accepted treatment for patients with severe chronic respiratory failure. Our reasoning, therefore, was that if asthma is a cause of severe chronic respiratory failure in non-smokers we should be able to find non-smoking asthmatics within a large population of patients on LTOT. The aim of our study (Asthma and Long-term Oxygen Therapy, "ALOT") was to investigate the prevalence of non-smoking asthmatics in patients on LTOT in a multi-centre, cross-sectional study. METHODS: Between June and September 2003 we screened all subjects on long-term domiciliary oxygen therapy in three different hospitals in the North-East area of Italy (within the provinces of Ferrara and Bologna). Taken collectively, we have found one-hundred and eighty-four patients on LTOT. We have reviewed their clinical data (age, sex, smoking, history and physical examination, arterial blood gas analysis, pulmonary function). RESULTS: 114 patients (all smokers) fulfilled the diagnostic criteria for COPD. Seventy patients (all smokers) had other diseases. We were unable to find any non-smokers in our screened population of subjects on long-term domiciliary oxygen therapy. Furthermore, there was no past history of asthma and/or acute wheezing episodes in either of the patient groups. CONCLUSIONS: This data suggests that asthma is an uncommon cause of severe chronic respiratory failure necessitating long-term domiciliary oxygen therapy in non-smokers and supports the current consensus that asthma and COPD are different diseases with differing stages of severity and the concept that long-term avoidance of active smoking is fundamental for the prevention of severe chronic respiratory failure.

Ectopic thymoma simulating a pericardial cyst.

We present a case of a 53 year old man with a thymoma near the pericardium, a rare ectopic localisation of thymoma. A round radiodensity found at the right cardiophrenic angle was initially suspected at the echocardiography to be a pericardial cyst. The diagnosis of thymoma was made only after histopathological examination of the surgically re-sected lesion.

Impact of transition zone biopsies in detection and evaluation of prostate cancer.

OBJECTIVE: To analyze the impact of 2 systematic transition zone (TZ) biopsies in addition to systematic sextant biopsies in an effort to establish the importance of cancer detected in the transition zone. METHODS: Between November 1995 and October 1996, TRUS-guided systematic sextant peripheral zone (PZ) and two additional TZ biopsies were performed on 189 consecutive men. Radical retropubic prostatectomy (RRP) was performed to 13 patients with organ-confined prostate cancer. The biopsy results of the 52 patients with cancer and the pathological specimens of the patients who underwent surgery were compared. RESULTS: Of the 189 patients, 52 (27.5%) had prostate cancer of whom 20 (38.5%) both in the PZ and TZ, 31 (59.6%) only in the PZ, and 1 (1.9%) in the TZ only. Of the 96 patients with high serum PSA levels despite normal DRE, 14 had prostate cancer. TZ cancer only rate was 7.1% (1 in 14 patients) in this group. RRP was performed to 8 patients who had cancer only in the PZ and 5 patients in both TZ and PZ. The pathological stages of the postoperative specimens and extracapsular extension rates of those with cancer in the PZ and TZ were significantly higher (p = 0.029 and p = 0.008, respectively). CONCLUSIONS: Routine TZ biopsy does not substantially increase the prostate cancer detection rate, however it can be useful in selected patient groups. If further studies reveal the relationship of cancer in the transition zone, higher capsular extension rate (pT3 cancer) and higher pathological stage after radical surgery, then TZ biopsies may yield additional information that might influence the therapeutic approach.

Modified "pluck" nephroureterectomy for upper urinary tract disorders: combined endourologic and open approach.

Nephroureterectomy is the standard surgical approach for upper urinary tract transitional-cell carcinoma (TCC) and many other conditions. In 1952, a modification of the conventional method was described in which a transurethral resection of the ureteral meatus and intramural ureter is undertaken until the remaining ureter has no attachment to the bladder. The resected area and the distal tip of the ureter are coagulated, and the ureter is removed in continuity with the kidney through a single flank incision. Since January 1990, we have performed 12 nephroureterectomies with this technique (9 men and 3 women with an average age of 61.8 years, ranging from 35 to 73). Six of them were operated on for a TCC of the upper urinary tract, and the postoperative follow-up of these patients was from 6 to 54 months (mean 18.6). Within the follow-up period, tumor has not recurred either at the resected trigonal area or in the retroperitoneum, and only one patient has had a tumor distant from the site of ureteric resection. One patient with bladder TCC, who had a suspect kidney mass on the left side detected by CT, underwent nephroureterectomy with this technique. Five patients had primary renal disorders and upper tract calculous problems, in which nephroureterectomy was required. After the transurethral resection, an indwelling catheter was left in the bladder for 4 days. We believe that our experience confirms the feasibility of this technique in order to improve and simplify nephroureterectomy. Therefore, we recommend the modified "pluck" technique in all patients who are candidates for an operation requiring nephroureterectomy, as it gives considerable benefit to the patient.