Monolithic thin-film lithium niobate broadband spectrometer with one nanometre resolution.

Miniaturised optical spectrometers are attractive due to their small footprint, low weight, robustness and stability even in harsh environments such as space or industrial facilities. We report on a stationary-wave integrated Fourier-transform spectrometer featuring a measured optical bandwidth of 325 nm and a theoretical spectral resolution of 1.2 nm. We fabricate and test on lithium niobate-on-insulator to take full advantage of the platform, namely electro-optic modulation, broad transparency range and the low optical loss achieved thanks to matured fabrication techniques. We use the electro-optic effect and develop innovative layouts to overcome the undersampling limitations and improve the spectral resolution, thus providing a framework to enhance the performance of all devices sharing the same working principle. With our work, we add another important element to the portfolio of integrated lithium-niobate optical devices as our spectrometer can be combined with multiple other building blocks to realise functional, monolithic and compact photonic integrated circuits.

High-bandwidth thermo-optic phase shifters for lithium niobate-on-insulator photonic integrated circuits.

Phase shifters are key components of large-scale photonic integrated circuits. For the lithium niobate-on-insulator (LNOI) platform, thermo-optic phase shifters (TOPS) have emerged as a more stable and compact alternative to common electro-optic phase shifters (EOPSs), which are prone to anomalous behavior and drifting at low frequencies. Here, we model and experimentally characterize the influence of geometry on the performance of metal strip TOPSs. Compared to EOPSs, a 10-fold reduction of the voltage-length product is measured and bandwidths beyond 100 kHz are demonstrated, while keeping the footprint as low as 0.04 mm2. This shows the potential of TOPSs as small-scale building blocks for stable tuning and switching in LNOI photonic circuits.

Extreme electro-optic tuning of Bragg mirrors integrated in lithium niobate nanowaveguides.

Bragg reflectors (BRFs) are essential elements in optical telecommunication and sensing applications. Their miniaturization down to the sub-micron scale has been achieved in silicon-on-insulator chips. However, their tunability is limited only to thermal tuning. In order to achieve a faster and more practical tunability operation, here we report on electro-optically tunable BRFs with ∼14 dB signal filtering on a lithium-niobate-on-insulator platform, while keeping sub-micron cross-sections. Due to the lithium niobate electro-optic properties and the chosen electrodes configuration, a Bragg tunability coefficient of 23.37±0.55 pm/V is achieved, which enhances ∼33 times the tunability performance of state-of-the-art BRFs.

Prevalence of vestibular dysfunction in patients with vestibular schwannoma using video head-impulses and vestibular-evoked potentials.

We sought to investigate the utility of new non-invasive tests of semicircular-canal and otolith function that are usable in the neuro-otology office practice in patients with vestibular schwannoma. Fifty patients with vestibular schwannoma were assessed using a 5-item battery consisting of air-conducted cervical- and bone conducted ocular-vestibular-evoked myogenic potentials (AC cVEMPs and BC oVEMPs) and video head impulse testing (vHIT) in all three canal planes. VEMP asymmetry ratios, latencies, and vHIT gains were used to determine the test sensitivity, relationship with tumour size and the pattern of vestibular nerve involvement. The percentage of abnormalities for each of the five tests for the entire sample ranged between 36.2-61.7%. In 58.3 % of patients, test abnormalities were referable to both superior and inferior vestibular nerve divisions. Selective inferior nerve dysfunction was identified in 10.4% and superior nerve dysfunction in 12.5%. The remaining 18.8% of patients demonstrated a normal test profile. The sensitivity of the 5-item battery increased with tumour size and all patients with medium to large (>14 mm) schwannoma had at least two abnormal vestibular test result. Our results indicate that dysfunction of the superior and inferior vestibular nerve evolves in parallel for most patients with schwannoma. Unexplained vHIT and VEMP asymmetry should alert otologists and neurologists to undertake imaging in patients presenting with non-specific disequilibrium or vertigo.

Activities of everyday life with high spinal loads.

Activities with high spinal loads should be avoided by patients with back problems. Awareness about these activities and knowledge of the associated loads are important for the proper design and pre-clinical testing of spinal implants. The loads on an instrumented vertebral body replacement have been telemetrically measured for approximately 1000 combinations of activities and parameters in 5 patients over a period up to 65 months postoperatively. A database containing, among others, extreme values for load components in more than 13,500 datasets was searched for 10 activities that cause the highest resultant force, bending moment, torsional moment, or shear force in an anatomical direction. The following activities caused high resultant forces: lifting a weight from the ground, forward elevation of straight arms with a weight in hands, moving a weight laterally in front of the body with hanging arms, changing the body position, staircase walking, tying shoes, and upper body flexion. All activities have in common that the center of mass of the upper body was moved anteriorly. Forces up to 1650 N were measured for these activities of daily life. However, there was a large intra- and inter-individual variation in the implant loads for the various activities depending on how exercises were performed. Measured shear forces were usually higher in the posterior direction than in the anterior direction. Activities with high resultant forces usually caused high values of other load components.

Serum level of a soluble form of endoglin (CD105) is decreased after Goeckerman's therapy of psoriasis.

BACKGROUND: Goeckerman's therapy (GT) of psoriasis is based on daily application of pharmacy grade coal tar on affected skin with subsequent exposure to UV light. Disturbances in angiogenic activity are characteristic for the immunopathogenesis of psoriasis. The aim of study was to evaluate the influence of GT of psoriasis on proinflammatory and angiogenic activities expressed as changes in levels of endoglin (CD105). METHODS: Serum levels of a soluble form of endoglin were measured in peripheral blood samples of 38 patients with psoriasis before and after therapy. Sixty three otherwise healthy blood donors serve as a control group. The efficacy of GT was expressed as changes in Psoriasis Area and Severity Index (PASI). RESULTS: PASI score was significantly diminished by GT (p < 0.001). Serum levels of soluble CD105 were significantly diminished after GT. The serum level of soluble CD105 dropped from 7.85 +/- 2.26 ng/ml before therapy to 7.01 +/- 1.71 ng/ml after therapy (p = 0.0002). Compared to serum levels of soluble CD105 in healthy blood donors, serum levels of soluble CD105 in patients before GT were significantly higher (p < 0.001) and remained elevated after therapy (p < 0.001). Angiogenic activity expressed as serum endoglin is diminished in patients with psoriasis treated by GT.

Three-dimensional analysis of the vestibular end organs in relation to the stapes footplate and piston placement.

OBJECTIVE: Measurements of the proximity of the membranous labyrinth to the stapes footplate show considerable variation. Largely, such measurements have been from histologic sections of fixed temporal bones, which may be affected by shrinkage artifact and perspective distortion in the 2-dimensional plane. To overcome these problems, the present study undertook an analysis of the 3-dimensional (3D) architecture of the relationship of the stapes to the membranous labyrinth using high-resolution X-ray micro-computed tomography. METHODS: Eleven temporal bones were fixed with Karnovsky's fixative (known to minimize shrinkage), soaked in 2% osmium tetroxide, and scanned in a micro-computed tomography scanner. The otic capsule was intact to exclude sectioning artifact, and no alcohol was used to avoid tissue shrinkage. Measurements were taken in a vertical plane to provide distances from the utricle and saccule to the footplate, and 3D reconstruction of the spatial relationship of these structures was carried out. The relationship of these structures to a stapes piston also was studied. RESULTS: The safest area of piston placement was the central and inferior part of the footplate. This was safe up to 0.5 mm depth at all areas except posterosuperiorly where the utricular macula is, on average, only 0.61 mm away from the footplate. The angle of insertion of the piston also influences the end result. CONCLUSION: Two-dimensional information about vestibular end organ location should serve as a guideline only because the operative field is 3D, and the relationship of the piston to the vestibular labyrinth changes with the angle of placement.

CC and CXC chemokines patterns in psoriasis determined by protein array method were influenced by Goeckerman's therapy.

Goeckerman's therapy (GT) of psoriasis is based on daily application of pharmacy grade coal tar on affected skin with subsequent exposure to UV light. The aim of this study was to evaluate the influence of Goeckerman's therapy of psoriasis on the levels of proangiogenic chemokines ENA-78 (CXCL5, Epithelial Cell Derived Neutrophil Attractant-78), GRO alpha (CXCL1, Growth-Related Oncogene), IL-8 (CXCL8, Interleukin-8), MCP-1 (CCL2, Monocyte Chemotactic (Chemoattractant) Protein 1) and RANTES (CCL5, Regulated on Activation of Normal T Cell Expressed and Secreted) in peripheral blood of 22 children's patients with psoriasis. 22 otherwise healthy children serve as a control group. The serum levels of chemokines were determined by commercial membrane protein array technique (RayBiotech, USA). Efficacy of Goeckerman's therapy was delineated by PASI score. Disease activity was significantly diminished by Goeckerman's therapy (p < 0.001). Serum levels of GRO alpha and MCP-1 in patients before GT were significantly higher than those measured in healthy blood donors (GRO alpha: p = 0.0128 and MCP-1: p = 0.0003). Serum levels of GRO alpha, MCP-1 and RANTES were significantly diminished by GT (GRO alpha: p = 0.002, MCP-1: p = 0.048 and RANTES: p = 0.0131). Compared to the healthy controls, serum level of MCP-1 remained significantly increased in psoriasis patients after GT (p < 0.0001). In conclusion, we found that the GT of psoriasis influenced the serum levels of proinflammatory and proangiogenic chemokines, especially GRO alpha, MCP-1 and RANTES. It could be the cause for decreased proangiogenic activity which is described after GT of psoriasis.