Assessment of the Structural Vibration Effect on Plasma Current Measurement Using a Fiber Optic Current Sensor in ITER.

In this paper, we assess the effect of cryostat bridge vibrations on the plasma current measurement accuracy when using a fiber optic current sensor (FOCS) in ITER. The impact of vibrations on the light polarization state was first experimentally investigated using a miniaturized mock-up which represented a relevant part of the ITER FOCS structure. The set-up was then numerically simulated using the Jones matrix approach. Equivalent vibration matrices obtained from the experiment were used in the simulations to determine the effect of the vibrations on the FOCS accuracy. It is demonstrated that although the vibrations imply some changes in the polarization state, this effect can be strongly reduced when a proper low-birefringent spun optical fiber is used. The ITER requirement regarding the plasma current measurement accuracy can therefore be fulfilled.

Polymeric tunable wavelength filter with two-stage cascaded tilted Bragg gratings.

Wavelength-division multiplexed optical communication systems used in 5G networks require tunable wavelength filters with narrow bandwidth for 100 GHz channel spacing, wide wavelength range to cover 16 channels, and a side mode suppression ratio (SMSR) exceeding 30 dB. To fabricate wavelength filters satisfying these specifications, tunable Bragg grating filters based on polymeric optical waveguides are proposed. The combination of mode-sorting waveguide and tilted Bragg grating enables the extraction of Bragg reflected signals to another path, without using an external circulator. Moreover, the double reflection by the two-stage cascaded structure produces narrower reflection bandwidth, improved SMSR characteristics, and reduced adjacent-channel crosstalk through the suppression of undesired mode coupling. The proposed device exhibits a 20 dB bandwidth of 1.0 nm and SMSR of 35 dB, over the entire wavelength-tuning range.

Silicon nitride optical phased array based on a grating antenna enabling wavelength-tuned beam steering.

An optical phased array (OPA) in silicon nitride (SiN) is conspicuously highlighted as a vital alternative to its counterpart in silicon. However, a limited number of studies have been conducted on this array in terms of wavelength-tuned beam steering. A SiN OPA has been proposed and implemented with a grating antenna that incorporated an array of shallow-etched waveguides, rendering wavelength-tuned beam steering along the longitudinal direction. To accomplish a superior directionality on a wavelength-tuned beam steering, the spectral beam emission characteristics of the antenna have been explored from the viewpoint of a planar structure that entails a buried oxide (BOX), a SiN waveguide core, and an upper cladding. Two OPA devices having substantially different thicknesses of the resonant cavities, established by combining the BOX and SiN core, were considered theoretically and experimentally to scrutinize the spectral emission characteristics of the antenna on beam steering. Both of the fabricated OPA devices steered light by an angle of 7.4° along the longitudinal direction for a wavelength ranging from 1530 to 1630 nm, while they maintained a divergence angle of 0.2°×0.6° in the longitudinal and lateral directions. Meanwhile, the OPA fabricated on a substantially thick BOX layer featured a limited steering performance to attain a stabilized response over a broad spectral region. We examined the influence of the cavity thickness on the spectral response of the antenna in terms of optical thickness. Based on the two antenna characteristics, it was confirmed that the grating antenna emitted the beam with a higher efficiency when the optical thickness of the cavity corresponded to odd integer multiples of the quarter wavelength. This work is a considerable strategy for designing a stabilized SiN OPA over a desired spectral region.

Temporal response of polymer waveguide beam scanner with thermo-optic phase-modulator array.

Solid-state light detection and ranging, capable of performing beam scanning without using any mechanical moving parts, requires a phase-modulator array. Polymers facilitate the fabrication of efficient phase modulators with low drive power, owing to their high thermo-optic (TO) effect and low thermal conductivity. We designed and fabricated a polymeric phase-modulator array and analyzed the temporal response of the TO phase modulator. The frequency response of the phase modulator was measured for a Mach-Zehnder interferometer (MZI), and the transfer function was modeled in terms of multiple poles and zeros. The frequency response of a fabricated beam-scanning device incorporating the TO phase modulator was also measured. The temporal response of the beam scanner was confirmed to coincide well with that of the MZI modulator. The device exhibited a fast rise time of 12 ms, accompanied by slight power variations appearing for a long period (over hundreds of seconds), which originated from the inherent viscoelastic effect of the polymer materials.

Sonography of Wrist Ganglion Cysts: Which Location Is Most Common?

OBJECTIVES: The literature states that wrist ganglion cysts are most commonly dorsal; however, our experience suggests a volar location is more common. The purpose of this study was to identify the locations of ganglion cysts of the wrist as imaged with sonography. METHODS: After Institutional Review Board approval with informed consent waived, retrospective review of wrist sonography reports from January to April 2016 was completed. Only patients who had a comprehensive evaluation that included the dorsal and volar wrist were included. Ultrasound images were reviewed to characterize wrist ganglion cysts. RESULTS: The study group consisted of 98 subjects (78% female, 22% male) (median age, 51 years; range 13-79) with 124 wrist ganglion cysts, where 69% (86 of 124) were volar and 31% (38 of 124) were dorsal. Ganglion cysts were located between the radial artery and flexor carpi radialis in 63% (78 of 124), followed by a dorsal location superficial to the scapholunate ligament in 20% (25 of 124), other dorsal locations in 11% (13 of 124), and other volar locations in 6% (8 of 124). With dorsal ganglion cysts, the scapholunate ligament when imaged appeared normal in 91% (20 of 22). Ganglion cysts were multilocular/multilobular in all subjects. CONCLUSIONS: The most common location for wrist ganglion cysts is in the volar wrist, particularly between the radial artery and flexor carpi radialis tendon, appearing multilocular or multilobular with a mean largest dimension of 1.0 cm. Given the propensity of ganglion cysts to occur at this site, attention to this area when imaging the wrist with sonography or magnetic resonance imaging should be considered.

GAREM1 regulates the PR interval on electrocardiograms.

PR interval is the period from the onset of P wave to the start of the QRS complex on electrocardiograms. A recent genomewide association study (GWAS) suggested that GAREM1 was linked to the PR interval on electrocardiograms. This study was designed to validate this correlation using additional subjects and examined the function of Garem1 in a mouse model. We analyzed the association of rs17744182, a variant in the GAREM1 locus, with the PR interval in 5646 subjects who were recruited from 2 Korean replication sets, Yangpyeong (n = 2471) and Yonsei (n = 3175), and noted a significant genomewide association by meta-analysis (P = 2.39 × 10-8). To confirm the function of Garem1 in mice, Garem1 siRNA was injected into mouse tail veins to reduce the expression of Garem1. Garem1 transcript levels declined by 53% in the atrium of the heart (P = 0.029), and Garem1-siRNA injected mice experienced a significant decrease in PR interval (43.27 ms vs. 44.89 ms in control, P = 0.007). We analyzed the expression pattern of Garem1 in the heart by immunohistology and observed specific expression of Garem1 in intracardiac ganglia. Garem1 was expressed in most neurons of the ganglion, including cholinergic and adrenergic cells. We have provided evidence that GAREM1 is involved in the PR interval of ECGs. These findings increase our understanding of the regulatory signals of heart rhythm through intracardiac ganglia of the autonomic nervous system and can be used to guide the development of a therapeutic target for heart conditions, such as atrial fibrillation.

Bias-free optical current sensors based on quadrature interferometric integrated optics.

A reflective quadrature interferometer was constructed by integrating polymeric optical waveguide components, to demonstrate an optical current sensor that could operate without bias feedback control. In order to obtain two interference signals with a phase difference of 90°, half-wave and quarter-wave plates were inserted in the polymeric optical waveguide chip, and a polarization-dependent birefringence modulator was used for the initialization of the optical sensor, including detector gain adjustment. During the bias-free operation of the sensor, the measurement error was less than ± 0.2%, and it was confirmed that the sensor output was stable for 15 h even if the operating point was not maintained.

Polymer waveguide WDM channel selector operating over the entire C and L bands.

A tunable channel selector operating over both the C and L bands of wavelength-division-multiplexing optical network is proposed based on a thermo-optic tunable Bragg grating device in a polymer waveguide. A tilted Bragg grating cascaded with an asymmetric Y-branch waveguide effectively implements a small Bragg-reflection wavelength filter that does not require an external circulator. To increase the operating wavelength span of the channel selector, two Bragg gratings with different periods are fabricated on a single substrate for covering C and L bands, respectively. A wide tuning range over 80 nm along with a narrow bandwidth is demonstrated. Moreover, the polarization dependence of the reflection spectrum is observed to be less than 0.1 nm.

Csk Regulates Blood Pressure by Controlling the Synthetic Pathways of Aldosterone.

BACKGROUND: Blood pressure is regulated by a network of diverse physiological pathways. The C-terminal Src kinase (CSK) locus (15q24) is associated with blood pressure in various ethnic groups. It was recently reported thatCskinsufficiency increases blood pressure through Src. The mechanisms of hypertension inCsk+/-mice are examined further in this study.Methods and Results:To identify a causal component responsible for hypertension inCsk+/-, the heart rate was measured by electrocardiogram and plasma volume by Evans blue dilution. Plasma volume increased inCsk+/-compared with wild-types, while the heart rate did not change. Plasma sodium and aldosterone levels rose consistently inCsk+/-vs. wild-types, and spironolactone, a mineralocorticoid receptor antagonist, reduced blood pressure. The amounts of Sgk1 and Na+/K+-ATPase (NKA) increased in the kidney ofCsk+/-compared with wild-types. It was also found that Cyp11b2 (aldosterone synthase) was upregulated in the adrenal glands ofCsk+/-, and that Csk was enriched in the zona glomerulosa of adrenals, the major site of aldosterone production in the normal mouse. CONCLUSIONS: The results of the present study identify a physiological pathway by which blood pressure is regulated, in which the insufficiency ofCskinduces aldosterone production with zonal specificity in the adrenal glands, increasing sodium reabsorption and plasma volume and thus resulting in hypertension.

Integrated-optic current sensors with a multimode interference waveguide device.

Optical current sensors based on polarization-rotated reflection interferometry are demonstrated using polymeric integrated optics and various functional optical waveguide devices. Interferometric sensors normally require bias feedback control for maintaining the operating point, which increases the cost. In order to resolve this constraint of feedback control, a multimode interference (MMI) waveguide device is integrated onto the current-sensor optical chip in this work. From the multiple outputs of the MMI, a 90° phase-shifted transfer function is obtained. Using passive quadrature demodulation, we demonstrate that the sensor could maintain the output signal regardless of the drift in the operating bias-point.

Tumors and Tumor-like Abnormalities of the Midfoot and Forefoot.

The differential diagnosis for a midfoot or forefoot mass or mass-like abnormality includes several common benign and malignant pathologies. Evaluation with imaging can often provide a diagnosis, or at least several likely etiologies, and guide management. Determining if a mass is cystic or solid with ultrasound or MRI can limit the differential diagnosis. Identifying the abnormality at a specific anatomical site, such as a bursa, peripheral nerve, plantar aponeurosis, or tendon, can often suggest a correct diagnosis. Correlation with radiography is essential to determine potential osseous origin or involvement and further characterize matrix mineralization. Imaging evaluation can effectively characterize a mass or mass-like abnormality of the midfoot or forefoot, which can provide a precise or limited differential diagnosis and guide further management for biopsy or other treatment.

Ultrasound-Guided Percutaneous Tenotomy.

Of the many treatment options for tendinopathy, percutaneous tenotomy has been used throughout the body with success. With this procedure, a needle is repeatedly passed into the abnormal tendon with the goal of converting a chronic degenerative process to an acute inflammatory condition that will progress to tendon healing. Ultrasound guidance for this procedure is essential to ensure that the abnormal region of the tendon is accurately targeted. The treatment has few contraindications, and negligible complications have been described. This article reviews the rationale behind tenotomy for the treatment of tendinopathy and the ultrasound-guided technique. The current literature comparing the results of tenotomy to other percutaneous tendon treatments is also reviewed, although many of the other tendon injection treatments incorporate tenotomy as part of the procedure.

Integrated optic current transducers incorporating photonic crystal fiber for reduced temperature dependence.

Optical current transducers (OCT) are indispensable for accurate monitoring of large electrical currents in an environment suffering from severe electromagnetic interference. Temperature dependence of OCTs caused by its components, such as wave plates and optical fibers, should be reduced to allow temperature-independent operation. A photonic crystal fiber with a structural optical birefringence was incorporated instead of a PM fiber, and a spun PM fiber was introduced to overcome the temperature-dependent linear birefringence of sensing fiber coil. Moreover, an integrated optic device that provides higher stability than fiber-optics was employed to control the polarization and detect the phase of the sensed optical signal. The proposed OCT exhibited much lower temperature dependence than that from a previous study. The OCT satisfied the 0.5 accuracy class (IIEC 60044-8) and had a temperature dependence less than ± 1% for a temperature range of 25 to 78 °C.

Sonographic Differentiation Between Schwannomas and Neurofibromas in the Musculoskeletal System.

OBJECTIVES: The purpose of this study was to determine key features and define a strategy for differentiation between schwannomas and neurofibromas using sonography. METHODS: This retrospective study was approved by the Institutional Review Board at our hospital, and informed consent was waived. We reviewed sonograms of pathologically proven schwannomas and neurofibromas of the extremities and body wall. On grayscale images, tumors were evaluated on the basis of their size, maximum-to-minimum diameter ratio, shape, contour, margin, location, encapsulation, echogenicity, echo texture, cystic changes, presence of intratumoral calcifications, presence of a target sign, and presence of an entering or exiting nerve. If an entering or exiting nerve was identified, the nerve-tumor position and nerve-tumor transition were characterized. On color Doppler images, the presence and amount of vascularity were evaluated. Student t tests were used for analysis of continuous variables (size, maximum-to-minimum diameter ratio, and age); χ(2) and Fisher exact tests were used for analysis of categorical variables. RESULTS: A total of 146 pathologically proven tumors, including 115 schwannomas and 31 neurofibromas of the extremities and body wall, were included. The maximum diameter, maximum-to-minimum diameter ratio, contour, cystic portion, nerve-tumor position, nerve-tumor transition, and vascularity were significantly different in schwannomas versus neurofibromas (P < .05), and a lobulated contour, fusiform shape, and hypovascularity of neurofibromas could be helpful for differentiation when a prediction model is considered. The nerve-tumor position, nerve-tumor transition, and maximum-to-minimum diameter ratio were also significantly different between groups (P < .05) and thus could be useful for differentiation of neurogenic tumors. CONCLUSIONS: Sonographic findings are helpful in differentiating between schwannomas and neurofibromas.

Ultrasound-Guided Fenestration of Tendons About the Hip and Pelvis: Clinical Outcomes.

OBJECTIVES: Percutaneous ultrasound-guided needle fenestration has been used to treat tendinopathy of the elbow, knee, and ankle with promising results. The purpose of this study was to evaluate the clinical outcome of ultrasound-guided fenestration of tendons about the hip and pelvis. METHODS: After Institutional Review Board approval, a retrospective search of imaging reports from January 1, 2005, to June 30, 2011, was completed to identify patients treated with ultrasound-guided tendon fenestration about the hip or pelvis. Subsequent clinic notes were retrospectively reviewed to determine whether the patient showed marked improvement, some improvement, no change, or worsening symptoms. RESULTS: The study group consisted of 22 tendons in 21 patients with an average age of 55.8 years (range, 26.7-77.0 years). The treated tendons included 11 gluteus medius (9 tendinosis and 2 partial tears), 2 gluteus minimus (both tendinosis), 8 hamstring (6 tendinosis and 2 partial tears), and 1 tensor fascia latae (tendinosis). The average interval to clinical follow-up was 70 days (range, 7-813 days). There was marked improvement in 45.5% (10 of 22), some improvement in 36.4% (8 of 22), no change in symptoms in 9.1% (2 of 22), and worsening symptoms in 9.1% (2 of 22). There were no patient variables (age, chronicity of symptoms, sex, tendon, tendinosis versus tear, prior physical therapy, and prior corticosteroid injection) that were significantly different between patients who improved and those who did not. There were no cases of a subsequent tendon tear or infection. CONCLUSIONS: Clinical follow-up after ultrasound-guided fenestration of the gluteus medius, gluteus minimus, proximal hamstring, and tensor fascia latae tendons showed that 82% of patients had improvement in their symptoms.

Sonography of cat scratch disease.

OBJECTIVES: To characterize the sonographic features of cat scratch disease and to identify features that allow differentiation from other causes of medial epitrochlear masses. METHODS: After Institutional Review Board approval was obtained, patients who underwent sonography for a medial epitrochlear mass or lymph node were identified via the radiology information system. Patients were divided into 2 groups: cat scratch disease and non-cat scratch disease, based on pathologic results and clinical information. Sonograms were retrospectively reviewed and characterized with respect to dimension, shape (round, oval, or lobular), symmetry, location (subcutaneous or intramuscular), multiplicity, echogenicity (anechoic, hypoechoic, isoechoic, hyperechoic, or mixed), hyperechoic hilum (present or absent), adjacent anechoic or hypoechoic area, hyperemia (present or absent), pattern of hyperemia if present (central, peripheral, or mixed), increased posterior through-transmission (present or absent), and shadowing (present or absent). Sonographic findings were compared between the patients with and without cat scratch disease. RESULTS: The final patient group consisted of 5 cases of cat scratch disease and 16 cases of other causes of medial epitrochlear masses. The 2 sonographic findings that were significantly different between the cat scratch disease and non-cat scratch disease cases included mass asymmetry (P = .0062) and the presence of a hyperechoic hilum (P = .0075). The other sonographic findings showed no significant differences between the groups. CONCLUSIONS: The sonographic finding of an epitrochlear mass due to cat scratch disease most commonly is that of a hypoechoic lobular or oval mass with central hyperemia and a possible adjacent fluid collection; however, the presence of asymmetry and a hyperechoic hilum differentiate cat scratch disease from other etiologies.

Sonography of the accessory head of the biceps brachii.

Anatomic variations in the anterior aspect of the shoulder, such as an accessory head of the biceps brachii muscle, are not uncommon. The magnetic resonance imaging and arthroscopic appearance of the accessory head of the biceps brachii has been recently described. This series demonstrates the sonographic appearance of the accessory head of the biceps brachii in the bicipital groove. It is an asymptomatic, flat, echogenic structure with average measurements of 7.7 × 1.2 mm in cross section. Knowledge of this anatomic variant can avoid the misdiagnosis of a longitudinal split tear and improve the accuracy of sonography.

Inguinal lymph nodes: size, number, and other characteristics in asymptomatic patients by CT.

PURPOSE: The purpose of this study was to establish normative data for the CT appearance of inguinal lymph nodes. MATERIALS AND METHODS: After Institutional Review Board approval, search of the radiology information system identified 500 consecutive CT examinations of the pelvis. Patients were included if no lower extremity or perineum pathology, or history of malignancy at the time of CT examination, and a clinical note documenting no tumor at least 2 years after the CT. The final study group was 77 patients. CT examinations were retrospectively reviewed and bilateral inguinal lymph nodes were characterized by size (short axis and largest size in general), number, and presence of fat attenuation. RESULTS: The mean short-axis inguinal lymph node size was 5.4 mm (range 2.1-13.6 mm), measured at 8.8 mm two standard deviations above the mean. The mean number of superficial and deep inguinal lymph nodes was 10.7 (range 3-18) and 1.2 per patient (range 1-2), respectively. Superficial and deep inguinal nodes showed internal fat attenuation in 85 and 78% of nodes, and were oval in shape in 95 and 78%, respectively. CONCLUSION: Inguinal lymph nodes in asymptomatic patients have a mean short axis of 5.4 mm, a short axis of 8.8 mm at two standard deviations above the mean, and are multiple and symmetric in size and number (4-20 per patient). Normal inguinal lymph nodes were commonly oval in shape and contained fat, although such findings may be absent in smaller lymph nodes.

Distal pectoralis major tears: sonographic characterization and potential diagnostic pitfalls.

OBJECTIVES: Distinction between musculotendinous tears of the pectoralis major and distal tendon avulsions is important, as the latter typically requires surgical repair. The objective of this study was to characterize the sonographic appearances of surgically proven distal tendon avulsion tears of the pectoralis major. METHODS: A retrospective search of the radiology database (2001-2011) revealed 22 cases of pectoralis major tears on sonography, of which 9 had surgical correlation. Sonograms were retrospectively characterized by 3 fellowship-trained musculoskeletal radiologists in consensus with respect to the location and size of the fluid collection and the presence of tendon or tendonlike tissue superficial to the biceps brachii tendon. RESULTS: At surgery, complete distal tendon avulsions or tears of the sternal head of the pectoralis were present in all 9 cases: isolated in 6 and combined with clavicular head tears in 3. The location of the fluid collection was at the musculotendinous junction in 89% (8 of 9) and medial to the biceps brachii tendon in 11% (1 of 9), with a mean largest dimension of 3.8 cm (range, 0.7-6.2 cm). In no case was fluid seen at the humeral attachment of the pectoralis. In 67% (6 of 9), linear thickened hypoechoic tissue was seen superficial to the biceps brachii tendon, which simulated an abnormal but intact tendon, whereas in 33% (3 of 9), a normal distal pectoralis tendon was seen. CONCLUSIONS: Surgically proven distal pectoralis major tendon avulsions most commonly showed fluid collections at the musculotendinous junction and not at the humeral shaft, with either a normal tendon or hypoechoic tendonlike tissue over the biceps brachii long-head tendon. These findings may potentially cause misdiagnosis of distal tendon avulsions or tears as musculotendinous injuries.

Ultrasound and MRI of the peroneal tendons and associated pathology.

Lateral ankle pain is common with overuse and sports-related injuries and may cause considerable morbidity. The differential diagnosis of lateral ankle pain is extensive. Disorders of the peroneal tendons should be an important consideration during interpretation of a routine ankle magnetic resonance imaging (MRI) or ultrasound (US). This article presents a review of the common causes of peroneal tendon pathology with particular reference to anatomy, US, and MRI features. The importance of dynamic evaluation with ultrasound is also emphasized.