Tunable high-index photonic glasses

Materials with extreme photonic properties such as maximum diffuse reflectance, high albedo, or tunable band gaps are essential in many current and future photonic devices and coatings. While photonic crystals, periodic anisotropic structures, are well established, their disordered counterparts, photonic glasses (PGs), are less understood despite their most interesting isotropic photonic properties. Here, we introduce a controlled high index model PG system. It is made of monodisperse spherical TiO$_2$ colloids to exploit strongly resonant Mie scattering for optimal turbidity. We report spectrally resolved combined measurements of turbidity and light energy velocity from large monolithic crack-free samples. This material class reveals pronounced resonances enabled by the possibility to tune both the refractive index of the extremely low polydisperse constituents and their radius. All our results are rationalized by a model based on the energy coherent potential approximation, which is free of any fitting parameter. Surprisingly good quantitative agreement is found even at high index and elevated packing fraction. This class of PGs may be the key to optimized tunable photonic materials and also central to understand fundamental questions such as isotropic structural colors, random lasing or strong light localization in 3D.Comment: Main text: 8 pages, 4 figures; Supporting Information: 5 pages, 5 figure

Thalamic reticular impairment underlies attention deficit in Ptchd1Y/− mice

Developmental disabilities, including attention-deficit hyperactivity disorder (ADHD), intellectual disability (ID), and autism spectrum disorders (ASD), affect one in six children in the USA. Recently, gene mutations in patched domain containing 1 (PTCHD1) have been found in ∼1% of patients with ID and ASD. Individuals with PTCHD1 deletion show symptoms of ADHD, sleep disruption, hypotonia, aggression, ASD, and ID. Although PTCHD1 is probably critical for normal development, the connection between its deletion and the ensuing behavioural defects is poorly understood. Here we report that during early post-natal development, mouse Ptchd1 is selectively expressed in the thalamic reticular nucleus (TRN), a group of GABAergic neurons that regulate thalamocortical transmission, sleep rhythms, and attention. Ptchd1 deletion attenuates TRN activity through mechanisms involving small conductance calcium-dependent potassium currents (SK). TRN-restricted deletion of Ptchd1 leads to attention deficits and hyperactivity, both of which are rescued by pharmacological augmentation of SK channel activity. Global Ptchd1 deletion recapitulates learning impairment, hyper-aggression, and motor defects, all of which are insensitive to SK pharmacological targeting and not found in the TRN-restricted deletion mouse. This study maps clinically relevant behavioural phenotypes onto TRN dysfunction in a human disease model, while also identifying molecular and circuit targets for intervention.Simons Foundation Autism Research Initiative (Grant 307913)National Institutes of Health (U.S.) (Grant R01MH097104)National Institute of Mental Health (U.S.) (Grant R01MH097104)National Institutes of Health (U.S.) (Grant R01MH107680

Assessment of Middle Ear Anatomy Teaching Methodologies Using Microscopy versus Endoscopy: A Randomized Comparative Study.

Teaching methodologies for the anatomy of the middle ear have not been investigated greatly due to the middle ear's highly complex structure and hidden location inside of the temporal bone. The aim of this randomized study was to quantitatively compare the suitability of using microscope- and endoscope-based methods for teaching the anatomy of the middle ear. We hypothesize that the endoscopic approach will be more efficient compared to the microscopic approach. To answer the study questions, 33 sixth-year medical students, residents and otorhinolaryngology specialists were randomized either into the endoscopy or the microscopy group. Their anatomical knowledge was assessed using a structured anatomical knowledge test before and after each session. Each participant received tutoring on a human cadaveric specimen using one of the two methods. They then performed a hands-on dissection. After 2-4 weeks, the same educational curriculum was repeated using the other technique. The mean gains in anatomical knowledge for the specialists, residents, and medical students were +19.0%, +34.6%, and +23.4%, respectively. Multivariate analyses identified a statistically significant increase in performance for the endoscopic method compared to the microscopic technique (P < 0.001). For the recall of anatomical structures during dissection, the endoscopic method outperformed the microscopic technique independently of the randomization or the prior training level of the attendees (P < 0.001). In conclusion, the endoscopic approach to middle ear anatomy education is associated to an improved gain in knowledge as compared to the microscopic approach. The participants subjectively preferred the endoscope for educational purposes

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

Objective: The insertion of the electrode array is a critical step in cochlear implantation. Herein we comprehensively investigate the impact of the alignment angle and feed-forward speed on deep insertions in artificial scala tympani models with accurate macro-anatomy and controlled frictional properties. Methods: Motorized insertions (n=1033) were performed in six scala tympani models with varying speeds and alignment angles. We evaluated reaction forces and micrographs of the insertion process and developed a mathematical model to estimate the normal force distribution along the electrode arrays. Results: Insertions parallel to the cochlear base significantly reduce insertion energies and lead to smoother array movement. Non-constant insertion speeds allow to reduce insertion forces for a fixed total insertion time compared to a constant feed rate. Conclusion: In cochlear implantation, smoothness and peak forces can be reduced with alignment angles parallel to the scala tympani centerline and with non-constant feed-forward speed profiles. Significance: Our results may help to provide clinical guidelines and improve surgical tools for manual and automated cochlear implantation

Assessment of jugular bulb variability based on 3D surface models: quantitative measurements and surgical implications.

PURPOSE High-riding jugular bulbs (JBs) among other anatomical variations can limit surgical access during lateral skull base surgery or middle ear surgery and must be carefully assessed preoperatively. We reconstruct 3D surface models to evaluate recent JB classification systems and assess the variability in the JB and surrounding structures. METHODS 3D surface models were reconstructed from 46 temporal bones from computed tomography scans. Two independent raters visually assessed the height of the JB in the 3D models. Distances between the round window and the JB dome were measured to evaluate the spacing of this area. Additional distances between landmarks on surrounding structures were measured and statistically analyzed to describe the anatomical variability between and within subjects. RESULTS The visual classification revealed that 30% of the specimens had no JB, 63% a low JB, and 7% a high-riding JB. The measured mean distance from the round window to the jugular bulb ranges between 3.22 ± 0.97 mm and 10.34 ± 1.41 mm. The distance measurement (error rate 5%) was more accurate than the visual classification (error rate 15%). The variability of the JB was higher than for the surrounding structures. No systematic laterality was found for any structure. CONCLUSION Qualitative analysis in 3D models can contribute to a better spatial orientation in the lateral skull base and, thereby, have important implications during planning of middle ear and lateral skull base surgery

Hearing-Preserving Approaches to the Internal Auditory Canal: Feasibility Assessment from the Perspective of an Endoscope.

OBJECTIVE Minimally invasive transcanal transpromontorial endoscopic approaches to the internal auditory canal sacrifice the cochlea. Two hearing-preserving approaches, the exclusively endoscopic transcanal infracochlear approach and the endoscope-assisted transmastoid retrolabyrinthine approach, have been controversially discussed in the literature. In this study, we examine the feasibility of these 2 approaches by means of three-dimensional surface models, a population-based analysis of the available surgical space, and dissections in human whole-head specimens. METHODS We reconstructed three-dimensional surface models based on clinical high-resolution computed tomography scans of 53 adult temporal bones. For both approaches, we measured the maximal extensions and the area of the surgical access windows located between landmarks on the surrounding anatomic structures. We then identified the limiting extensions and derived the cumulative distribution to describe the available surgical space. Dissections were performed to validate the corridors and landmark selection. RESULTS The limiting extension for the infrachochlear approach is 7.0 ± 2.7 mm from the round window to the dome of the jugular bulb. The limiting extension for the retrolabyrinthine approach is 6.4 ± 1.5 mm from the dura of the posterior fossa to the facial nerve. The cumulative distribution shows that 80% of the cohort have access window extensions ≥3 mm for both approaches. CONCLUSIONS This study shows that in a high percentage of the measured cohort, the access windows are sufficiently large for endoscopic approaches to the internal auditory canal. With appropriate instrumentation, these hearing-preserving minimally invasive approaches may evolve into alternatives to surgical treatment

Experimental Investigation of Liquid and Vapor Mass Flows in a Parallel Tube Evaporator

One of the major challenges in the evaluation of an evaporator heat exchanger in refrigeration cycles is to provide reasonable measurement data. Especially if the evaporator is multi-flow and therefore the measurement of the mass flow at one location and the evaluation of the overall energy balance is not sufficient for the characterization of the heat exchanger. In the present work, an evaporator of a capacity of approx. 1.2 kW, consisting of a distributor, a collector and four parallel evaporator tubes in which heat was introduced, was experimentally investigated. The four evaporator tubes made of stainless steel with an inner diameter of 2 mm, an outer diameter of 4 mm and a length of 800 mm were led out of the distributor and into the collector at a right angle at a distance of 90 mm from each other. All tubes form a plane. To keep the geometry of the joints as uniform as possible, commercially available fittings were used. The evaporator was investigated as part of a refrigeration cycle with several adjustment possibilities like mass flow, subcooling, and pressure. To determine the mass flow and vapor quality distribution within the heat exchanger, each evaporator tube was divided into two heating sections of 400 mm and 200 mm length respectively with an intermediate measuring section of 200 mm for pressure and temperature. The first sections were heated by variable electrical heat loads, uniformly distributed over a length of 345 mm. The heat load was adjusted so that a slight superheating of approx. 4 K occurred at the outlet. In the second sections a constant electrical heat load was uniformly applied over a length of 150 mm. Assuming that a thermal equilibrium between the phases in the first sections is established, the heat loads can be used to draw conclusions about the respective mass flows of liquid refrigerant. In the second sections, the constant heat flow can be used to draw conclusions about the different total mass flows due to the different outlet temperatures. The measurements were carried out in our own laboratory for different vapor qualities from x=0 to x=0.3 and different overall total mass flows of the cycle ranging from 5, 7.5 and 10 kg/h to partly 20 kg/h. During the measurements, different inclinations of the evaporator relative to the horizontal plane were realized as well, so that a large number of measurement results were finally recorded. The measurement setup allows the evaluation of liquid and vapor refrigerant mass flow rates in each evaporator channel and makes a comparison between the sum of the four individual total mass flow rates and the overall total mass flow rate of the cycle possible. The results show the influence of the variable gravity vector and flow velocity on the distribution. In the horizontal measuring point the tube furthest away from the distributor inlet exhibits the highest vapor quality of all 4 tubes, contrary to what was expected. Finally, the results are used to validate the simulation models of the industrial project partner