Magnetic Turbulence and Current Drive during Local Helicity Injection.

Magnetic measurements during dc helicity injection tokamak startup indicate Alfvénic turbulence in the injected current streams mediates magnetic relaxation and results in macroscopic plasma current drive. Localization of such activity to the injected current streams, a bias voltage dependence to its onset, and higher-order spectral analysis indicate super-Alfvénic electrons excite instabilities that drive the observed turbulence. Measured fluctuation helicity is consistent with an α-dynamo electromotive force driving net current comparable to the macroscopic equilibrium current density. These results imply new constraints for scaling local helicity injection to larger devices.

Land use change impacts on floods at the catchment scale: Challenges and opportunities for future research.

Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage, and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long-term experiments on physical-chemical-biological process interactions, and a focus on connectivity and patterns across spatial scales. It is suggested that these strategies will stimulate new research that coherently addresses the issues across hydrology, soil and agricultural sciences, forest engineering, forest ecology, and geomorphology.

Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta.

Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-to-magnetic pressure ratio (ß_{t}), low internal inductance, high elongation, and nonsolenoidal current drive is a central goal of present tokamak plasma research. Stable access to this desirable parameter space is demonstrated in plasmas with ultralow aspect ratio and high elongation. Local helicity injection provides nonsolenoidal sustainment, low internal inductance, and ion heating. Equilibrium analyses indicate ß_{t} up to ∼100% with a minimum |B| well spanning up to ∼50% of the plasma volume.

[Imaging of the lumbosacral plexus : Diagnostics and treatment planning with high-resolution procedures]. / Bildgebung des Plexus lumbosacralis : Diagnostik und Therapieplanung mithilfe hochaufgelöster Verfahren.

BACKGROUND: Technical advances in magnetic resonance (MR) and ultrasound-based neurography nowadays facilitate the radiological assessment of the lumbosacral plexus. OBJECTIVE: Anatomy and imaging of the lumbosacral plexus and diagnostics of the most common pathologies. MATERIAL AND METHODS: Description of the clinically feasible combination of magnetic resonance imaging (MRI) and ultrasound diagnostics, case-based illustration of imaging techniques and individual advantages of MRI and ultrasound-based diagnostics for various pathologies of the lumbosacral plexus and its peripheral nerves. RESULTS: High-resolution ultrasound-based neurography (HRUS) is particularly valuable for the assessment of superficial structures of the lumbosacral plexus. Depending on the examiner's experience, anatomical variations of the sciatic nerve (e. g. relevant in piriformis syndrome) as well as more subtle variations, for example as seen in neuritis, can be sonographically depicted and assessed. The use of MRI enables the diagnostic evaluation of more deeply located nerve structures, such as the pudendal and the femoral nerves. Modern MRI techniques, such as peripheral nerve tractography allow three-dimensional depiction of the spatial relationship between nerves and local tumors or traumatic alterations. This can be beneficial for further therapy planning. CONCLUSION: The anatomy and pathology of the lumbosacral plexus can be reliably imaged by the meaningful combination of MRI and ultrasound-based high resolution neurography.

Control and automation of the Pegasus multi-point Thomson scattering system.

A new control system for the Pegasus Thomson scattering diagnostic has recently been deployed to automate the laser operation, data collection process, and interface with the system-wide Pegasus control code. Automation has been extended to areas outside of data collection, such as manipulation of beamline cameras and remotely controlled turning mirror actuators to enable intra-shot beam alignment. Additionally, the system has been upgraded with a set of fast (∼1 ms) mechanical shutters to mitigate contamination from background light. Modification and automation of the Thomson system have improved both data quality and diagnostic reliability.

A novel, cost-effective, multi-point Thomson scattering system on the Pegasus Toroidal Experiment (invited).

A novel, cost-effective, multi-point Thomson scattering system has been designed, implemented, and operated on the Pegasus Toroidal Experiment. Leveraging advances in Nd:YAG lasers, high-efficiency volume phase holographic transmission gratings, and increased quantum-efficiency Generation 3 image-intensified charge coupled device (ICCD) cameras, the system provides Thomson spectra at eight spatial locations for a single grating/camera pair. The on-board digitization of the ICCD camera enables easy modular expansion, evidenced by recent extension from 4 to 12 plasma/background spatial location pairs. Stray light is rejected using time-of-flight methods suited to gated ICCDs, and background light is blocked during detector readout by a fast shutter. This ∼103 reduction in background light enables further expansion to up to 24 spatial locations. The implementation now provides single-shot Te(R) for ne > 5 × 1018 m-3.

High Confinement Mode and Edge Localized Mode Characteristics in a Near-Unity Aspect Ratio Tokamak.

Tokamak experiments at near-unity aspect ratio A≲1.2 offer new insights into the self-organized H-mode plasma confinement regime. In contrast to conventional A∼3 plasmas, the L-H power threshold P_{LH} is ∼15× higher than scaling predictions, and it is insensitive to magnetic topology, consistent with modeling. Edge localized mode (ELM) instabilities shift to lower toroidal mode numbers as A decreases. These ultralow-A operations enable heretofore inaccessible J_{edge}(R,t) measurements through an ELM that show a complex multimodal collapse and the ejection of a current-carrying filament.

Visualization of the Long Thoracic Nerve using High-Resolution Sonography.

PURPOSE: The long thoracic nerve (LTN) innervates the serratus anterior muscle (SA) which plays an important role in shoulder function. Evaluation of the LTN has so far been restricted to clinical assessment and partly electromyography and neurography. Progress of high-resolution ultrasound (HRUS) increasingly enables visualization of small peripheral nerves and their pathologies. We therefore aimed at (a) clarifying the possibility of visualization of the LTN from its origin to the most distal point in the supraclavicular region visible and (b) developing an ultrasound protocol for routine use. We further present two cases of patients with LTN pathology. METHODS: The study consisted of two parts: Part 1 included 4 non-enbalmed human bodies in whom the LTN (n = 8) was located and then marked by ink injection. Correct identification was confirmed by anatomical dissection. Part 2 included 20 healthy volunteers whose LTN (n = 40) was assessed independently by two radiologists. Identification of the LTN was defined as consensus in recorded images. RESULTS: LTN was clearly visible in all anatomical specimens and volunteers using HRUS and could be followed until the second slip of the serratus anterior muscle from the supraclavicular region. In anatomical specimens, dissection confirmed HRUS findings. For all volunteers, consensus was obtained. The mean nerve diameter was 1.6 mm ±â€Š0.3 (range 1.1 - 2.1 mm) after the formation of the main trunk. DISCUSSION: We hereby confirm a reliable possibility of visualization of the LTN in anatomical specimens as well as in volunteers. We encourage HRUS of the LTN to be part of the diagnostic work-up in patients presenting with scapular winging, shoulder weakness or pain of unknown origin.

High-Resolution Ultrasound for Diagnostic Assessment of the Great Auricular Nerve--Normal and First Pathologic Findings.

PURPOSE: The great auricular nerve (GAN) is a sensory branch of the superficial cervical plexus. While its blockade is an established procedure, little is known about the ultrasound appearance of pathologic conditions of the GAN itself. We, therefore, aimed to evaluate the possibility of the visualization and diagnostic assessment of the GAN along its entire course by means of high-resolution ultrasound (HRUS). MATERIALS AND METHODS: To assess the feasibility of visualization, we performed HRUS with an 18 MHz probe, HRUS-guided, fine-needle ink markings and consecutive dissection in six anatomical specimens. Then, we measured the diameter of the GAN in healthy volunteers and finally performed a retrospective review of patients referred for HRUS examinations because of pain within GAN territory between August 1, 2012 and August 1, 2013. RESULTS: The GAN was clearly visible with HRUS from its formation to the final branches, and was marked successfully on both sides in all anatomical specimens (n = 12). The mean average in-vivo was 0.14 cm ± 0.03 (range 0.08-0.2). Seven cases of patients with GAN pathologies of various origins (idiopathic, traumatic, tumorous and iatrogenic) were identified, of which 6 were visible on HRUS and all of which could be confirmed by complete resolution of symptoms after selective HRUS-guided GAN block. CONCLUSION: This study confirms the reliable ability to visualize the GAN with HRUS throughout its course, both in anatomical specimens and in vivo. The provided cases show that pathologies of the GAN seem to have a variety of causes and may not be rare. We, therefore, encourage the use of HRUS in patients with unclear pain in the auricular, periauricular and posterior-lateral head.

Coarse and fine root plants affect pore size distributions differently.

AIMS: Small scale root-pore interactions require validation of their impact on effective hydraulic processes at the field scale. Our objective was to develop an interpretative framework linking root effects on macroscopic pore parameters with knowledge at the rhizosphere scale. METHODS: A field experiment with twelve species from different families was conducted. Parameters of Kosugi's pore size distribution (PSD) model were determined inversely from tension infiltrometer data. Measured root traits were related to pore variables by regression analysis. A pore evolution model was used to analyze if observed pore dynamics followed a diffusion like process. RESULTS: Roots essentially conditioned soil properties at the field scale. Rooting densities higher than 0.5 % of pore space stabilized soil structure against pore loss. Coarse root systems increased macroporosity by 30 %. Species with dense fine root systems induced heterogenization of the pore space and higher micropore volume. We suggested particle re-orientation and aggregate coalescence as main underlying processes. The diffusion type pore evolution model could only partially capture the observed PSD dynamics. CONCLUSIONS: Root systems differing in axes morphology induced distinctive pore dynamics. Scaling between these effective hydraulic impacts and processes at the root-pore interface is essential for plant based management of soil structure.

Root induced changes of effective 1D hydraulic properties in a soil column.

AIMS: Roots are essential drivers of soil structure and pore formation. This study aimed at quantifying root induced changes of the pore size distribution (PSD). The focus was on the extent of clogging vs. formation of pores during active root growth. METHODS: Parameters of Kosugi's lognormal PSD model were determined by inverse estimation in a column experiment with two cover crops (mustard, rye) and an unplanted control. Pore dynamics were described using a convection-dispersion like pore evolution model. RESULTS: Rooted treatments showed a wider range of pore radii with increasing volumes of large macropores >500 µm and micropores <2.5 µm, while fine macropores, mesopores and larger micropores decreased. The non-rooted control showed narrowing of the PSD and reduced porosity over all radius classes. The pore evolution model accurately described root induced changes, while structure degradation in the non-rooted control was not captured properly. Our study demonstrated significant short term root effects with heterogenization of the pore system as dominant process of root induced structure formation. CONCLUSIONS: Pore clogging is suggested as a partial cause for reduced pore volume. The important change in micro- and large macropores however indicates that multiple mechanic and biochemical processes are involved in root-pore interactions.

Field quantification of wetting-drying cycles to predict temporal changes of soil pore size distribution.

Wetting-drying (WD) cycles substantially influence structure related soil properties and processes. Most studies on WD effects are based on controlled cycles under laboratory conditions. Our objective was the quantification of WD cycles from field water content measurements and the analysis of their relation to the temporal drift in the soil pore size distribution. Parameters of the Kosugi hydraulic property model (rm,Kosugi, σKosugi) were derived by inverse optimization from tension infiltrometer measurements. Spectral analysis was used to calculate WD cycle intensity, number and duration from water content time series. WD cycle intensity was the best predictor (r2 = 0.53-0.57) for the temporal drift in median pore radius (rm,Kosugi) and pore radius standard deviation (σKosugi). At lower soil moisture conditions the effect of cycle intensity was reduced. A bivariate regression model was derived with WD intensity and a meteorological indicator for drying periods (ET0, climatic water balance deficit) as predictor variables. This model showed that WD enhanced macroporosity (higher rm,Kosugi) while decreasing pore heterogeneity (lower σKosugi). A drying period with high cumulative values of ET0 or a strong climatic water balance deficit on the contrary reduced rm,Kosugi while slightly increasing σKosugi due to higher frequency at small pore radius classes. The two parameter regression model was applied to predict the time course of soil pore size distribution parameters. The observed system dynamics was captured substantially better by the calculated values compared to a static representation with averaged hydraulic parameters. The study showed that spectral analysis is an adequate approach for the quantification of field WD pattern and that WD intensity is a key factor for the temporal dynamics of the soil pore size distribution.

Environmental and management influences on temporal variability of near saturated soil hydraulic properties.

Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (- 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r2 = 0.43 to 0.59). Our results suggested that beside considering average management induced changes in soil properties (e.g. cover crop introduction), a dynamic approach to hydrological modeling is required to capture over-seasonal (tillage driven) and short term (environmental driven) variability in hydraulic parameters.

Sonographic imaging of abdominal and extraabdominal desmoids.

PURPOSE: To describe the sonographic imaging characteristics of abdominal and extraabdominal desmoids. MATERIALS AND METHODS: We retrospectively investigated 12 histologically and pathologically proven abdominal and extraabdominal desmoids. Two radiologists with musculoskeletal sonography experience reviewed sonographic images for lesion location, size, echotexture, and vascularity with agreement by consensus. RESULTS: Desmoids were seen in 9 females and 3 males. They manifested as slowly growing masses. Nine lesions were intramuscular and 3 were found within the subcutaneous adipose tissue. A typical sonographic feature of all intramuscular desmoids was the spindle-shaped margin at the tumor ends when scanned along the long axis of the affected muscle. The desmoids arising from the fascia had an irregular shape. Tumor vascularity was rich in 6 cases and poor in 6 cases. A fibrillar pattern within the tumor was found in 75% of the cases. CONCLUSION: A spindle-shaped appearance is common in intramuscular desmoids. Hyperechoic areas and a fibrillar pattern within desmoids are also common sonographic features.

Intraorbital plexiform neurofibroma in an NF-1-negative patient.

A 52-year-old patient presented with an orbital swelling and exophthalmos that enlarged over a period of about 40 years. The clinical examination showed massive exophthalmos and ptosis of the right eye without diplopia. The radiological investigation (MRI, CT and ultrasound) showed an unclear intraorbital mass with erosion of the orbital floor, infraorbital rim and orbital roof. The lesion was diagnosed histologically as a plexiform neurofibroma. The patient did not present any features of neurofibromatosis type 1 (NF-1) and molecular genetic analysis was unable to uncover a pathogenic sequence alteration in the NF-1 gene. Owing to the absence of clinical and ophthalmologic symptoms and the improbability of complete removal, the patient refused surgical intervention.

[Pictorial essay: Ultrasound of tumours and tumour-like lesions of peripheral nerves]. / Sonographisches Bildessay: Periphere Nerventumoren.

High-resolution ultrasound is an excellent diagnostic modality for visualising peripheral nerves and differentiate tumours of the peripheral nerve. With high-frequency transducers (5-15 MHz), peripheral nerves can be visualised, the hypoechoic nerve fascicles, the surrounding tissue and tumourous lesions including the relation to their nerve of origin can be evaluated. By using colour Doppler sonography (CDS), it is possible to detect and assess vascularisation of tumours of the nerve. We present sonographic features of common and uncommon benign and malignant tumours of the peripheral nerve.

Diagnostic quality of dynamic high-resolution ultrasonography of the TMJ--a pilot study.

The aim of this study was to compare sensitivity, specificity, accuracy and positive and negative predictive value for high-resolution ultrasonography (HR-US) in diagnosing degenerative changes, effusion and disk displacement using magnetic resonance imaging (MRI) as a reference. Over a period of 6 months, 100 patients with TMJ disorders (200 TMJs) were investigated by an experienced radiologist with HR-US and magnetic resonance imaging (MRI). The MRI investigation showed degenerative changes in 190 joints (95%), while an effusion was found in 59 (29.5%) joints. At closed-mouth position a disc dislocation was found in 138 joints (69%) and in maximum-mouth-opening position disc dislocation was diagnosed in 76 joints (38%). In the determination of degenerative changes HR-US showed a sensitivity of 94%, a specificity of 100% and an accuracy of 94%. In the detection of effusion HR-US yielded a sensitivity of 81%, a specificity of 100% and an accuracy of 95%. In the determination of disk displacement at closed-mouth position HR-US showed a sensitivity, specificity and an accuracy of 92% each. At maximum-mouth-opening position HR-US reached a sensitivity of 86%, a specificity of 91% and an accuracy of 90%. The results of the current study imply that HR-US is a valuable diagnostic imaging method of the TMJ which can be used as an alternative method to a MRI-investigation, but is yet not able to replace it. Further studies have to be done to reduce false-negative results.

Bilateral hand transplantation: bone healing under immunosuppression with tacrolimus, mycophenolate mofetil, and prednisolone.

PURPOSE: Little is known about bone healing after composite tissue transplantation that requires pharmacologic immunosuppression. Bone integration and callus development were assessed in bilateral hand transplantation. METHODS: In this study the course of callus development and callus maturation were assessed by color Doppler sonography and radiography in a double hand transplant and compared with forearm replantation. RESULTS: After hand transplantation, ingrowth of small vessels at the bone junction was observed at week 3, calcified callus became visible at month 4, and bone union was completed at month 11. A similar time course of bone integration was observed after replantation. Plating offered sufficient stability. A recipient periostal flap is thought to have improved blood supply and favored development and induction of callus. CONCLUSIONS: Bone healing after hand transplantation under immunosuppression with tacrolimus, mycophenolate mofetil, and prednisolone is identical to that after forearm replantation.

[Interobserver variation of the sonographic diagnosis of orbital floor fractures and fractures of the infraorbital margin]. / Reliabilität der sonographischen Diagnostik von Orbitabodenfrakturen und Frakturen des Infraorbitalrandes.

PURPOSE: The aim of the study was to evaluate the interobserver variation of the ultrasound diagnosis of orbital floor fractures and fractures of the infraorbital rim. MATERIAL AND METHODS: A total of 25 patients with a clinical diagnosis of an orbital trauma were investigated prospectively by computed tomography (CT) and ultrasonography (US). Inter-observer variation was calculated using the lambda coefficient (lambda). The US images were reassessed by two inexperienced investigators. RESULTS: The lambda value for the US investigation of the orbital floor showed poor reliability comparing the US findings with the results of the re-investigators. The comparison between the two re-investigators showed a good reliability for the US evaluation of the orbital floor. The lambda for the US investigation of the infraorbital margin showed a good reliability comparing the US findings with the results of the both re-investigators. The comparison of the two re-investigators showed a good reliability as well. CONCLUSION: Ultrasound is not yet an alternative method for the evaluation of orbital floor fractures and fractures of the infraorbital margin. To replace CT which is accepted as the current gold standard, further studies have to be done to reach a better diagnostic quality of the method and to achieve a better calibration of the investigations.