An EUV beamsplitter based on conical grazing incidence diffraction.

We present an innovative grating design based on conical diffraction which acts as an almost perfect and low-loss beamsplitter for extreme ultraviolet radiation. The scheme is based on a binary profile operated in grazing incidence along the grating bars under total external reflection. It is shown that periods of a few 10(2) nm may permit an exclusive (±1)(st) order diffraction with efficiencies up to ~ 35% in each of them, whereas higher evanescent orders vanish. In contrast, destructive interference eliminates the 0(th) order. For a sample made of SiO(2) on silicon, measured data and simulated results from rigorous coupled wave analysis procedures are given.

Stand-alone diamond binary phase transmission gratings for the EUV band.

We report on the development of true free-standing phase transmission gratings for the extreme ultraviolet band. An ultra-nanocrystalline, 300 nm thin diamond film on a backside etched silicon wafer is structured by electron-beam lithography to periods of 1 µm. In this way, flat and stable gratings of 400 µm in diameter are fabricated. First-order net efficiencies up to 28% are obtained from measurements at a synchrotron beamline within a wavelength range from 5.0 nm to 8.3 nm, whereas the 0th order is suppressed to 1% near 6.8 nm. Higher diffraction orders up to the 3rd one contribute less than 7% in sum to the far-field pattern.

Two classes of outer hair cells along the tonotopic axis of the cochlea.

The molecular basis of high versus low frequency hearing loss and the differences in the sensitivity of outer hair cells depending on their cochlear localization are currently not understood. Here we demonstrate the existence of two different outer hair cell phenotypes along the cochlear axis. Outer hair cells in low frequency regions exhibit early sensitivity for loss of Ca(v)1.3 (alpha1 subunit 1.3 forming the class D L-type voltage-gated Ca(2+) channel), while high frequency regions display a progressive susceptibility for loss of the Ca(2+)-activated large conductance K(+) (BK) channel. Despite deafness, young Ca(v)1.3-deficient mice displayed distortion-product otoacoustic emissions (DPOAEs), indicating functional outer hair cells in the higher frequency range of the cochlea. Considering that DPOAEs are also found in the human deafness syndrome DFNB9 caused by mutations in the synaptic vesicle protein otoferlin, we tested the expression of otoferlin in outer hair cells. Surprisingly, otoferlin showed a distinct tonotopic expression pattern at both the mRNA and protein level. Otoferlin-expressing, Ca(v)1.3 deletion-sensitive outer hair cells in the low frequency range could be clearly separated from otoferlin-negative, BK deletion-sensitive outer hair cells in the high frequency range. In addition, BK deletion led to a higher noise vulnerability in low frequency regions, which are normally unaffected by the BK deletion alone, suggesting that BK currents are involved in survival mechanisms of outer hair cells under noise conditions. Our findings propose new mechanisms and candidate genes for explaining high and low frequency hearing loss.

[The endosonographic staging of pancreatic carcinoma]. / Endosonographisches Staging des Pankreaskarzinoms.

Endoscopic ultrasound (EUS), conventional ultrasound (US), computed tomography (CT) and angiography were compared in their assessment of local resectability in 35 consecutive patients (19 men, 16 women; mean age 49.8 [42-821] years) with non-metastatic carcinoma of the pancreas. The findings were made prospectively and independently of each other. EUS proved to be superior to transabdominal US and to CT in the diagnosis of tumour infiltration of the portal and splenic veins. For the portal vein the sensitivity was 93% by EUS, 14% by US and 36% by CT. Corresponding figures for the splenic vein were 92%, 39% and 69%. EUS was markedly superior to angiography in the diagnosis of portal vein involvement (sensitivity of 93% and 36%, respectively), but the two methods had similar sensitivity regarding splenic vein infiltration (92 and 100%). Tumour involvement of the coeliac trunk was diagnosed with higher sensitivity angiographically (86%) than by EUS (57%), CT (71%) or US (29%). Regarding T and N staging, EUS was superior to both US and CT. These data indicate that EUS is the most accurate method for local tumour staging of potentially resectable pancreatic carcinoma. It can replace angiography in the diagnosis of portal vein infiltration.

Staging of pancreatic and ampullary carcinoma by endoscopic ultrasonography. Comparison with conventional sonography, computed tomography, and angiography.

In a prospective study, endoscopic ultrasonography was compared with transabdominal ultrasonography, computed tomography, and angiography in 60 consecutive patients with pancreatic (n = 46) and ampullary (n = 14) cancer considered to be candidates for surgery. The diagnostic value of these imaging procedures in determining local resectability was assessed. The diagnosis of ampullopancreatic malignancy was made by operation (n = 40) or puncture/biopsy (n = 20). In the 40 patients who underwent surgery, endoscopic ultrasonography was significantly superior to abdominal ultrasonography and computed tomography in determining tumor size and extent and lymph node metastases of pancreatic and ampullary cancer. Furthermore, involvement of the portal venous system as judged by histopathology or surgical exploration was correctly assessed by endoscopic ultrasonography in 95%, whereas angiography (85%), computed tomography (75%) and abdominal ultrasonography (55%) were less sensitive. Of 11 cases of portal venous infiltration found at surgery, endoscopic ultrasonography correctly predicted 10, abdominal ultrasonography only 1, computed tomography 4, and angiography 5 (P less than 0.05 for all three comparisons). Twenty patients did not undergo surgery for different reasons: of those, 9 patients were excluded from operation because of portal venous involvement as shown by angiography. Endoscopic ultrasonography detected portal venous invasion in all these cases. In contrast to the venous system, arterial encasement was less reliably detected by endoscopic ultrasonography. In conclusion, endoscopic ultrasonography is the most effective single imaging procedure for local tumor staging in pancreatic and ampullary cancer. Thus, endoscopic ultrasonography will improve the assessment of tumor resectability and further decrease the need for explorative laparotomy.

Endoscopic ultrasound in pancreatic tumor diagnosis.

In a prospective study from 1988 to 1990, 132 patients with suspected pancreatic tumor were examined with endoscopic ultrasound (EUS), transabdominal ultrasound (US), computed tomography (CT), and ERCP. The final diagnosis of 102 pancreatic tumors of different origin (76 malignant and 26 inflammatory tumors) and the exclusion of a pancreatic tumor in 30 patients was made by operation (N = 47), puncture (N = 36), autopsy (N = 3), or follow-up of a mean of 51 weeks (N = 46). Sensitivity and specificity in pancreatic tumor diagnosis were significantly higher for EUS (99% and 100%) than for US (67%/40%) and CT (77%/53%) and equal to ERCP (sensitivity 90%). This was even more obvious in small pancreatic tumors of 3 cm and less. However, as with the other imaging procedures, EUS was not able to differentiate reliably malignant from inflammatory pancreatic masses (accuracy 76% for malignancy and 46% for focal inflammation). From analysis of the endosonographic pattern of pancreatic tumors, no consistent morphologic features were identified which could have been specifically attributed to malignant or inflammatory masses. Our results show that EUS is superior to US and CT and equal to ERCP in pancreatic tumor diagnosis. In contrast to the indirect evidence obtained by ERCP, EUS provides direct visualization of tumor size and shape in almost all patients examined. Thus, EUS should be considered early in the evaluation of patients with suspected pancreatic tumors.

[Endoscopic ultrasound in small pancreatic tumors]. / Endoskopischer Ultraschall bei kleinen Pankreastumoren.

32 of 89 pancreatic tumors examined by endoscopic ultrasonography (EUS) from January 1986 to February 1990 had a diameter of 3 cm or less. The final diagnosis of a malignant (n = 28) or benign (n = 4) pancreatic neoplasma was achieved by operation, puncture or autopsy. The accuracy of EUS (100%) was higher than for ultrasound (61%), computed tomography (64%) or endoscopic-retrograde cholangiopancreatography (84%). The echopattern of the small pancreatic carcinomas showed, compared to larger neoplasms, less often regressive changes (21 vs. 77%) and a well demarcated or smooth tumor margin (25 vs. 2%). However, it is not possible to differentiate reliably a small malignant from a benign pancreatic tumor by the echofeatures alone. Since most pancreatic tumors are large at the time of clinical presentation, they can be visualized by conventional imaging methods in most cases. EUS adds clinically important information to the diagnosis of pancreatic carcinoma especially in small tumors.

[Endosonographic diagnosis of pancreatic tumors]. / Endosonographische Diagnostik bei Pankreastumoren.

140 patients (72 men, 68 women; mean age 57 [26-83] years) with suspected pancreatic tumours were investigated by endoscopic ultrasound (EUS) and also by conventional ultrasound, computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP). The EUS scans were performed with an echo-endoscope in the descending part of the duodenum (for the head of the pancreas) or in the stomach (for the body and tail). The definitive diagnosis or exclusion of a pancreatic tumour (malignant n = 85, benign n = 4, inflammatory n = 23, no tumour n = 28) was made at operation (n = 63), by needle biopsy (n = 35), at necropsy (n = 4) or by clinical follow up (n = 38, mean 10.5 months). The sensitivity and specificity of endoscopic ultrasound (99% and 100%) were superior to the results given by conventional ultrasound scans (71% and 39%), CT (82% and 46%) and ERCP (89% and 64%). This was also true of small tumours of 3 cm or less (EUS 100%, conventional ultrasound 57%, CT 68% and ERCP 89%). However, the differential diagnosis between malignant and inflammatory masses in the pancreas was not feasible by endoscopic ultrasound, either prospectively (detection rate 69%) or by comparative analyses of echo structure. Endoscopic ultrasound appears to be a valuable aid to the diagnosis or exclusion of pancreatic tumours. When conventional ultrasound and CT give negative or doubtful results it can be used in conjunction with or instead of ERCP to confirm the diagnosis.