Optical Coherence Tomography Guided Laser Cochleostomy: Towards the Accuracy on Tens of Micrometer Scale

Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned based on the residual bone thickness distribution. OCT itself is also used as a highly accurate tracking system for motion compensation between the target area and the optics. During ex vivo experimental evaluation on fresh porcine cochleae, the ablation process terminated automatically when the thickness of the residual tissue layer uniformly reached a predefined value. The shape of the resulting channel bottom converged to the natural curvature of the endosteal layer without injuring the critical structure. Preliminary measurements in OCT scans indicated that the mean absolute accuracy of the shape approximation was only around 20 mu m

Optical coherence tomography guided laser cochleostomy: towards the accuracy on tens of micrometer scale

Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned based on the residual bone thickness distribution. OCT itself is also used as a highly accurate tracking system for motion compensation between the target area and the optics. During ex vivo experimental evaluation on fresh porcine cochleae, the ablation process terminated automatically when the thickness of the residual tissue layer uniformly reached a predefined value. The shape of the resulting channel bottom converged to the natural curvature of the endosteal layer without injuring the critical structure. Preliminary measurements in OCT scans indicated that the mean absolute accuracy of the shape approximation was only around 20 μm

Terahertz Rectennas on Flexible Substrates Based on One-Dimensional Metal–Insulator–Graphene Diodes

Flexible energy harvesting devices fabricated in scalable thin-film processes are crucial for wearable electronics and the Internet of Things. We present a flexible rectenna based on a one-dimensional junction metal–insulator–graphene diode, offering low-noise power detection at terahertz (THz) frequencies. The rectennas are fabricated on a flexible polyimide film in a scalable process by photolithography using graphene grown by chemical vapor deposition. A one-dimensional junction reduces the junction capacitance and enables operation up to 170 GHz. The rectenna shows a maximum responsivity of 80 V/W at 167 GHz in free space measurements and minimum noise equivalent power of 80 pW/√Hz

A vision to strengthen resources and capacity of the Palestinian health research system: a qualitative assessment

The World Health Organization has proposed a global strategy to build a robust Health Research System Resources and Infrastructural Capacity (HRSRIC). Despite the growing research productivity, HRSRIC in Palestine has rarely been investigated.; To analyse perceptions of health research system performers to understand the status of HRSRIC, identify its gaps, and propose policy solutions to strengthen HRSRIC.; This qualitative study targeted 3 health sectors: government, academia, and local and international organizations. Fifty-two in-depth interviews and 6 focus group discussions were conducted with key informants who were selected purposively. Data were analysed using MAXQDA 12.; Despite the availability of competent personnel, the overall HRSRIC, such as human and financial resources, and facilities, forms a central challenge. HR financing is limited, unsustainable, and flows from external and individual sources. The public and private funds are largely in shortage with resources misallocation and donors' conditionality. HR quality is moderate while knowledge transfer and translation are not well conceptualized and inappropriately performed. Lack of governance, coordination, HRSRIC strategy, resource allocation, systematic and reliable data, evidence-informed culture, and environmental impacts are the main common gaps.; The overall status of HRSRIC in Palestine is still lacking and major challenges persist where the pace of strengthening efforts is steady. There is an emphasis that strengthening HRSRIC is an imperative step and real investment opportunity for building a successful health research system. Political commitment, consolidated leadership structure, operational capacity building strengthening strategy, resources mobilization, and sovereignty are key requirements

Mapping stakeholders of the Palestinian Health Research System: a qualitative study

There is a growing international and regional interest in Health Research Systems (HRSs) in light of a global strategy for HRS stakeholders' (HRSSHs) active involvement. HRSSHs in Palestine have rarely been investigated with regard to uncertainties.; This study aimed to analyse perceptions of HRSSHs in order to understand their roles and involvement, identify gaps, and offer policy solutions for stakeholders' engagement in the Palestinian HRS.; This qualitative study targeted three local Palestinian health sectors, government, academia, and local and international agencies. Data were collected through 52 in-depth interviews (IDIs) and 6 focus group discussions (FGDs) and then analysed using MAXQDA 12 software. Participants and institutions were selected purposively based on a set of criteria and peer review.; The overall HRS stakeholders' roles were unsatisfactory, with low involvement from society, the private sector, local and international sectors. The role of academia and the Ministry of Health is vital but observed moderate in health research while that of international agencies is weak due to conflicting agendas and lack of a guiding body. Most universities have poor representation in public decision-making and scarcity in health research potential and capacity. Interest-power imbalance among stakeholders is reported where political, organizational, and technical shortfalls were indicative of weak roles and low involvement, along with a lack of health research culture, structure, resources, defined roles, and network.; Tackling the inadequate roles, interests' disparity, and poor involvement of HRSSHs is imperative for HRS strengthening. Redefining HRSSHs' roles and involving all stakeholders is key through strategic dialogue, consolidated leadership, and resource mobilization

Influence of wavelength and accumulated fluence at picosecond laser-induced surface roughening of copper on secondary electron yield

Ultrashort-pulse laser processing of copper is performed in air to reduce the secondary electron yield (SEY). By UV (355 nm), green (532 nm), and IR (1064 nm) laser-light induced surface modification, this study investigates the influence of the most relevant experimental parameters, such as laser power, scanning speed, and scanning line distance (represented as accumulated fluence) on the ablation depth, surface oxidation, topography, and ultimately on the SEY. Increasing the accumulated laser fluence results in a gradual change from a Cu 2 O to a CuO-dominated surface with deeper micrometer trenches, higher density of redeposited surface particles from the plasma phase, and a reduced SEY. While the surface modifications are less pronounced for IR radiation at low accumulated fluence (,1000 J/cm2 ), analogous results are obtained for all wavelengths when reaching the nonlinear absorption regime, for which the SEY maximum converges to 0.7. Furthermore, independent of the extent of the structural transformations, an electron-induced surface conditioning at 250 eV allows a reduction of the SEY maximum below unity at doses of 5×10 -4 C/mm2 . Consequently, optimization of processing parameters for application in particle accelerators can be obtained for a sufficiently low SEY at controlled ablation depth and surface particle density, which are factors that limit the surface impedance and the applicability of the material processing for ultrahigh vacuum systems. The relations between pro- cessing parameters and surface features will provide guidance in treating the surface of vacuum components, especially beam screens of selected magnets of the Large Hadron Collider or of future colliders