Development of the 174 GHz collective Thomson scattering diagnostics at Wendelstein 7-X.

In this paper, we present the design and commissioning results of the upgraded collective Thomson scattering diagnostic at the Wendelstein 7-X stellarator. The diagnostic has a new radiometer designed to operate between the second and third harmonics of the electron cyclotron emission from the plasma at 171-177 GHz, where the emission background has a minimum and is of order 10-100 eV. It allows us to receive the scattered electromagnetic field with a significantly improved signal-to-noise ratio and extends the set of possible scattering geometries compared to the case of the original instrument operated at 140 GHz. The elements of the diagnostic are a narrowband notch filter and a frequency stabilized probing gyrotron that will allow measuring scattered radiation spectra very close to the probing frequency. Here, we characterize the microwave components applied to the radiometer and demonstrate the performance of the complete system that was achieved during the latest experimental campaign, OP2.1.

Impact of Magnetic Field Configuration on Heat Transport in Stellarators and Heliotrons.

We assess the magnetic field configuration in modern fusion devices by comparing experiments with the same heating power, between a stellarator and a heliotron. The key role of turbulence is evident in the optimized stellarator, while neoclassical processes largely determine the transport in the heliotron device. Gyrokinetic simulations elucidate the underlying mechanisms promoting stronger ion scale turbulence in the stellarator. Similar plasma performances in these experiments suggests that neoclassical and turbulent transport should both be optimized in next step reactor designs.

Demonstration of reduced neoclassical energy transport in Wendelstein 7-X.

Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak1 is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)2, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator's non-turbulent 'neoclassical' energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas3,4. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible1,5. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization.

Development of the ion cyclotron emission diagnostic for the W7-X stellarator.

An ion cyclotron emission (ICE) diagnostic is prepared for installation into the W7-X stellarator, with the aim to be operated in the 2022 experimental campaign. The design is based on the successful ICE diagnostic on the ASDEX Upgrade tokamak. The new diagnostic consists of four B-dot probes, mounted about 72° toroidally away (one module) from the neutral beam injector, with an unobstructed plasma view. Two of the B-dot probes are oriented parallel to the local magnetic field, aimed to detect fast magnetosonic waves. The remaining two probes are oriented poloidally, with the aim to detect slow waves. The radio frequency (RF) signals picked up by the probes are transferred via 50 Ω vacuum-compatible coaxial cables to RF detectors. Narrow band notch filters are used to protect the detectors from possible RF waves launched by the W7-X antenna. The signal will be sampled with a four-channel fast analog-to-digital converter with 14 bit depth and 1 GSample/s sampling rate. The diagnostic's phase-frequency characteristic is properly measured in order to allow measuring the wave vectors of the picked up waves.

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation.

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X.

Stellarators Resist Turbulent Transport on the Electron Larmor Scale.

Electron temperature gradient (ETG)-driven turbulence, despite its ultrafine scale, is thought to drive significant thermal losses in magnetic fusion devices-but what role does it play in stellarators? The first numerical simulations of ETG turbulence for the Wendelstein 7-X stellarator, together with power balance analysis from its initial experimental operation phase, suggest that the associated transport should be negligible compared to other channels. The effect, we argue, originates essentially from the geometric constraint of multiple field periods, a generic feature of stellarators.

Collective Thomson scattering diagnostic at Wendelstein 7-X.

A Collective Thomson Scattering (CTS) diagnostic is installed at Wendelstein 7-X for ion temperature measurements in the plasma core. The diagnostic utilizes 140 GHz gyrotrons usually used for electron cyclotron resonance heating (ECRH) as a source of probing radiation. The CTS diagnostic uses a quasi-optical transmission line covering a distance of over 40 m. The transmission line is shared between the ECRH system and the CTS diagnostic. Here we elaborate on the design, installation, and alignment of the CTS diagnostic and present the first measurements at Wendelstein 7-X.

Is ultraviolet exposure acquired at work the most important risk factor for cutaneous squamous cell carcinoma? Results of the population-based case-control study FB-181.

BACKGROUND: Squamous cell carcinoma (SCC) is one of the most frequent types of cancer constituting a significant public health burden. Prevention strategies focus on limiting ultraviolet (UV) exposure during leisure time. However, the relative impact of occupational and nonoccupational UV exposure for SCC occurrence is unclear. OBJECTIVES: To investigate the association between occupational and nonoccupational UV exposure for SCC in a multicentre population-based case-control study hypothesizing that high occupational UV exposure increases the risk of SCC. METHODS: Consecutive patients with incident SCC (n = 632) were recruited from a German national dermatology network. Population-based controls (n = 996) without history of skin cancer were recruited from corresponding residents' registration offices and propensity score matched to cases. Lifetime UV exposure, sociodemographic and clinical characteristics were assessed by trained physicians. Occupational and nonoccupational UV exposure doses were estimated by masked investigators using established reference values. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were assessed using conditional logistic regression adjusting for relevant confounders. RESULTS: Total solar UV exposure was significantly associated with increased SCC. The OR for high (> 90th percentile) vs. low (< 40th percentile) and high vs, moderate (40-59th percentile) occupational UV exposure was 1·95 (95% CI 1·19-3·18) and 2·44 (95% CI 1·47-4·06) for SCC. Adjusting for occupational UV exposure, nonoccupational UV exposure was not significantly related to SCC incidence. Dose-response relationships were observed for occupational but not for nonoccupational solar UV exposure. CONCLUSIONS: Solar occupational UV exposure is a major determinant of incident SCC. Our findings indicate that prevention strategies should be further expanded to the occupational setting.

[A rare case of conductive hearing loss : Isolated fracture of the manubrium mallei as a consequence of digital manipulation in the external auditory meatus]. / Eine seltene Ursache für Schallleitungsschwerhörigkeit : Isolierte Fraktur des Manubrium mallei durch digitale Manipulation im Meatus acusticus externus.

Isolated fracture of the handle of the malleus is a rare cause of conductive hearing loss and represents a challenge for the otolaryngologist in terms of past medical history, diagnostics, and therapy.

Absolute calibration of sniffer probes on Wendelstein 7-X.

Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of the Wendelstein 7-X empty vacuum vessel. Normalized absolute calibration coefficients agree with the cross-calibration coefficients that are obtained by the direct measurements, indicating that the measured absolute calibration coefficients and stray radiation levels in the vessel are valid. Close to the launcher, the stray radiation in the empty vessel reaches power levels up to 340 kW/m(2) per MW injected beam power. Furthest away from the launcher, i.e., half a toroidal turn, still 90 kW/m(2) per MW injected beam power is measured.

Non-invasive screening of diabetes risk by assessing abnormalities of sudomotor function.

BACKGROUND: The early detection of diabetes, and subsequent lifestyle intervention, may reduce the burden of diabetes and its complications. Several studies have identified a link between sudomotor dysfunction, insulin resistance, and pre-diabetes. The aim of this study was to evaluate the ability of a new non-invasive device EZSCAN evaluating sudomotor function to detect pre-diabetes in a German population at risk for diabetes. METHODS AND FINDINGS: 200 German subjects at risk for diabetes (mean age 56±14 years, BMI 28.4±5.4 kg/m2) were measured for anthropometric data on inflammatory parameters, including high sensitivity C reactive protein (hs-CRP). The subjects also underwent an oral glucose tolerance test with measurements of plasma glucose, insulin, proinsulin, C-peptide and free fatty acids during 2 h following glucose challenge. Indexes for sensitivity to insulin were calculated: SI using minimal model, HOMA-IR and Matsuda index. Based on the measurement of electrochemical sweat conductance, subjects were classified as no risk, moderate risk or high risk. According to this risk model classification, a significant difference was observed between OGTT-1 h (p=0.004), AUC glucose (p=0.011), AUC C-peptide (p<0.001), HOMA-IR (p=0.009), Matsuda (p=0.002), SI (p<0.001) and hs-CRP (p=0.025) after adjustment for age. Among the 54 subjects with impaired fasting glucose or impaired glucose tolerance according to WHO classification, 37 had a moderate risk and 15 a high risk according to the EZSCAN risk model classification. Among the 12 subjects with newly diagnosed diabetes, 2 had a moderate risk and 10 a high risk according to the risk model classification. No adverse event was reported during or after the study. CONCLUSIONS: These results, in accordance with a previous study performed in India, show that EZSCAN could be developed as a screening tool for diabetes risk, and could help to improve diabetes screening strategies. Results obtained from an at-risk population would have to be confirmed in a larger population.

[Facial swelling caused by small cell lung cancer: a rare differential diagnosis of angioedema]. / Gesichtsschwellung bei kleinzelligem Bronchialkarzinom: Eine seltene Differenzialdiagnose des Angioödems.

Non-inflammatory swelling in the head and neck area are usually caused by allergic angioedema. However, other differential diagnoses must always be considered. Superior vena cava syndrome is a rare differential diagnosis of angioedema. Since we treated two such patients within only a few weeks of one another with the initial supposition of an ACE inhibitor-induced angioedema, but who ultimately proved to have lung cancer, we would like to draw attention to this disease pattern.

[The risks of autogenous cartilage grafting in laryngotracheal reconstruction in adults]. / Risiko des autogenen Knorpeltransplantats bei laryngotrachealer Rekonstruktion bei Erwachsenen.

BACKGROUND: Laryngotracheal reconstruction with autogenous rib cartilage graft has become a well established surgical method for the repair of subglottic and glottic laryngotracheal stenoses in infants and children. There are far fewer reports on the application of this method in adult patients. In particular, detailed observations of the healing behaviour of autogenous adult rib cartilage grafts are lacking. MATERIAL AND METHOD: The course of disease in five adult female patients (age 25-47 years) who underwent one- or two-stage laryngotracheal reconstruction with rib cartilage grafts are reported. RESULTS: Primary healing was observed in the youngest patient (25 years) only. In the other four patients the cartilage graft had to be partly removed 4-6 weeks postoperatively due to partial necrosis, followed by open wound treatment. As a result of these measures a sufficiently large laryngotracheal lumen could be achieved in all cases. DISCUSSION: Partial ossification of the adult rib cartilage was considered the reason for the observed healing difficulties. Endoscopic follow-up showed that epithelialization of the free endolaryngeal surface of the cartilage graft, i.e. graft healing, takes at least 3 months. Therefore, close endoscopic follow-up during this period appears indispensable.

[Closure of nasoseptal defects in Germany: the current state of the art]. / Nasenseptumdefektverschlüsse in Deutschland: Eine aktuelle Bestandsaufnahme.

OBJECTIVE: 20 years after its first description, the bridge-flap technique according to Schultz-Coulon has proven to be the most successful method by far for the closure of nasoseptal defects. The number of nasoseptal defects being treated in Germany, and the treatment methods being used, are currently an unknown factor. MATERIAL AND METHODS: A questioning survey was sent to all 157 German ENT clinics. They were asked about the number of treatments of nasoseptal defects and the frequency of surgical techniques applied during 2007. RESULTS: 123 questionnaires were evaluated (return ratio=78.3%). In total, 777 nasoseptal defects were treated in Germany during 2007. 31 clinics treated no nasoseptal defects; at 71 clinics, 1-10, at 16 clinics, 11-20, and at 5 clinics, more than 30 nasoseptal defects were treated. 713 nasoseptal defects (91.8%) received surgical treatment, and 64 (8.2%) were treated by inserting a silicone button. With 556 patients (78%), the surgical closures of the nasoseptal defects took place with the help of the bridge-flap technique. CONCLUSIONS: The survey data show a clear tendency towards the surgical care of nasoseptal defects at ENT clinics in Germany. In comparison to the previous school of thought that, in view of doubtful surgical results, symptomatic septal defects should be treated somewhat conservatively, a paradigm shift thereby took place. The fact that in the overwhelming majority of cases (78%), the bridge-flap technique according to Schultz-Coulon is used suggests that the favourable chances of success of this method are mainly responsible for the increasing surgical treatment of nasoseptal defects.

[Surgical management of inverted papillomas of the nose and paranasal sinuses]. / Zum chirurgischen Behandlungskonzept bei invertierten Papillomen der Nase und Nasennebenhöhlen.

INTRODUCTION: Inverted papillomas require radical resection because of their high recurrence rate and expansive growth and the risk of malignant degeneration. Since the late 1980s surgical resection has been performed predominantly as an endoscopy-/microscopy-aided procedure through an endonasal approach. The extranasal approach is only used in the case of papillomas in unusual locations or ones that have expanded to an exceptional degree. The goal of the present study was a comparative evaluation of the results of this relatively new treatment strategy and of external sinus surgery in our own patients, with particular reference to the recurrence rate. PATIENTS AND METHODS: Since 1989 a total of 80 patients have undergone surgery for inverted papilloma and have been followed up at regular intervals by means of endoscopic examinations. In any patients with a recurrence the revision operation was carried out through an extranasal approach when the papilloma was in the anterior or laterocaudal maxillary sinus or in the frontal sinus; in all other cases an endonasal approach was used for the revision surgery. The mean period of follow-up was 43 months (range 15 months to 16years). RESULTS: In most patients (n=64, 80%) the endonasal surgical approach was used for the primary surgical treatment, while in 16 patients (20%) an extranasal approach was used initially. In 2 patients (2.6%) a squamous cell carcinoma was discovered adjacent to the papilloma. These two therapeutic special cases were not considered evaluable in the analysis of recurrences. Recurrences were seen in 14 patients (17.9%, n=78), in 11 patients after endonasal surgery (17.5%, n=11) and in 3 (20%, n=15) after extranasal resection. The majority of recurrences developed in patients with T3 papillomas. CONCLUSIONS: The recurrence rates observed after endonasal resection are comparable to those after extranasal surgery. Thus, a primary endonasal approach does not mean any prognostic disadvantage. This approach should therefore be given preference over extranasal approaches whenever possible, because there are fewer side-effects and recovery is faster than after extranasal surgery.

[Patients' satisfaction after nasal septal and turbinate surgery. Results of a questionnaire]. / Ergebnisse einer Umfrage zur Patientenzufriedenheit nach Nasenseptumplastik und Muschelbehandlung.

INTRODUCTION: Regarding the satisfaction of patients efficiency and outcome of surgery on the nasal septum and the turbinates regularly is the topic of controversial discussion and occasionally some health authorities doubt there is an indication for these procedures in general. Subjective and objective evaluation of surgical outcome do not necessarily match in all cases. METHODS: A standardized questionnaire was sent to patients having undergone surgery on the nasal septum and the turbinates 33-45 months ago at a university hospital and a non-university hospital. Topics (10 all together) were e. g.: nasal aeration, sense of smell, rhinorrhea, snoring, general condition. Statistic significance of each parameter was verified. RESULTS: 138 questionnaires were reviewed. 82% of the candidates reported better aeration of the nose after surgery. 71% stated to have benefited from the operation. A relevant positive effect on snoring, rhinorrhea, headache and sense of smell could not be proved. The results did no different whether surgery was performed at a university hospital or at a non-university-hospital. Older patients seem to profit more from the procedure than younger ones. DISCUSSION: The survey clearly shows, that surgery on the nasal septum with turbinoplasty has a positive effect on the nasal aeration and the general condition. Therefore its performance is well justified when after careful verification of the pre-conditions the indication for surgery is given.

[Electron microscopic studies of the rabbit nasal mucosa after short-term application of naphzoline nitrate]. / Elektronenmikroskopische Untersuchungen der Nasenschleimhaut des Kaninchens nach kurzzeitiger Applikation von Naphazolinnitrat.

BACKGROUND: Vasoconstricting nasal drops are applied frequently. Especially early ultrastructural alterations of the vessels were not examined up to now in animal models. Our goal was the systematic investigation of the submucosal vessels and the epithelium after topic application of naphazoline nitrate (Privin) in an animal model. METHODS: Three times daily over 6 days 3 ml of 0.1% naphazoline nitrate solution (Privin) were instilled into the right nasal cavity of 5 rabbits. At the 7th and 14th day an incisional biopsy of the lower nasal turbinate was carried out in ketamine/rompun anesthesia. RESULTS: In the naphazoline group the capillaries showed an edematous endothelium with narrowed lumina. Thrombosis of the arterioles were frequently observed. The more cubic epithelial cells had deciliated areas with microvilli. Venules, submucosal glands and the surrounding connective tissue was normally configurated. Analogous findings were also observed after 2 weeks. CONCLUSIONS: The disturbance of the microcirculation shows impressive endothelial alterations. These structural changes can result in nonreversible mucosal damages. A regeneration time of more than 1 week is assumable. Our results should be considered critically in order to prevent damages of the nasal mucosa.