BACKGROUND: Microvascular conflicts in hemifacial spasm typically occur at the facial nerve's root exit zone. While a pure microsurgical approach offers only limited orientation, added endoscopy enhances visibility of the relevant structures without the necessity of cerebellar retraction. METHODS: After a retrosigmoid craniotomy, a microsurgical decompression of the facial nerve is performed with a Teflon bridge. Endoscopic inspection prior and after decompression facilitates optimal Teflon bridge positioning. CONCLUSIONS: Endoscope-assisted microsurgery allows a clear visualization and safe manipulation on the facial nerve at its root exit zone.
Hemifacial Spasm , Microvascular Decompression Surgery , Polytetrafluoroethylene , Humans , Hemifacial Spasm/surgery , Microvascular Decompression Surgery/methods , Facial Nerve/surgery , Craniotomy/methods , Endoscopy/methods , Neuroendoscopy/methods , Microsurgery/methods , Female , Middle Aged , Male
OBJECTIVE: The surgical anatomy of the nervus intermedius (NI) is highly variable. The aim of this study was to describe the anatomy of the NI during endoscope-assisted microvascular decompression (MVD) in hemifacial spasm (HFS), and the involvement of the nerve in the vascular conflict. METHODS: The authors reviewed a prospectively maintained database for MVDs performed between 2002 and 2022 and extracted clinical data including patient demographics, symptoms, and offending vessel(s). Operative videos and photographs were analyzed retrospectively in an attempt to identify the NI. RESULTS: Endoscopic identification of the NI was possible in 139 of 435 MVDs. The anatomy is very variable. In 79 (56.8%) patients, a single-bundle pattern was detected, whereas a multiple-bundle pattern was identified in 60 (43.2%) patients. Overall the most common pattern was a single-bundle type A (49.7%). In 20.1%, a multiple-bundles type A was identified. In 4.3%, a single-bundle type B was detected. In 2.9% a single-bundle type C was found, and in just 0.7% a multiple-bundles type C was detected. A multiple-origin pattern (type D) was found in 31 patients (22.3%). The NI was frequently involved in the neurovascular conflict (approximately 85%). The type of NI or vascular compression pattern did not affect the results regarding the outcome or recurrence of HFS. CONCLUSIONS: The anatomy of the NI is for the first time evaluated endoscopically in MVD for HFS. The nerve had various anatomical patterns that were clearly identified. Further studies to evaluate the compression patterns in relation to NI neuralgia are warranted.
Nanoscale superlattice (SL) structures have proven to be effective in enhancing the thermoelectric (TE) properties of thin films. Herein, the main phase of antimony telluride (Sb2 Te3 ) thin film with sub-nanometer layers of antimony oxide (SbOx ) is synthesized via atomic layer deposition (ALD) at a low temperature of 80 °C. The SL structure is tailored by varying the cycle numbers of Sb2 Te3 and SbOx . A remarkable power factor of 520.8 µW m-1 K-2 is attained at room temperature when the cycle ratio of SbOx and Sb2 Te3 is set at 1:1000 (i.e., SO:ST = 1:1000), corresponding to the highest electrical conductivity of 339.8 S cm-1 . The results indicate that at the largest thickness, corresponding to ten ALD cycles, the SbOx layers act as a potential barrier that filters out the low-energy charge carriers from contributing to the overall electrical conductivity. In addition to enhancing the scattering of the mid-to-long-wavelength at the SbOx /Sb2 Te3 interface, the presence of the SbOx sub-layer induces the confinement effect and strain forces in the Sb2 Te3 thin film, thereby effectively enhancing the Seebeck coefficient and reducing the thermal conductivity. These findings provide a new perspective on the design of SL-structured TE materials and devices.
Several nanowire properties are strongly dependent on their diameter, which is notoriously difficult to control for III-Sb nanowires compared with other III-V nanowires. Herein environmental transmission electron microscopy is utilized to study the growth of Au nanoparticle seeded GaSb nanowires in situ. In this study, the real time changes to morphology and nanoparticle composition as a result of precursor V/III ratio are investigated. For a wide range of the growth parameters, it is observed that decreasing the V/III ratio increases the nanoparticle volume through Ga accumulation in the nanoparticle. The increase in nanoparticle volume in turn forces the nanowire diameter to expand. The effect of the V/III ratio on diameter allows the engineering of diameter modulated nanowires, where the modulation persisted after the growth. Lastly, this study demonstrates the observed trends can be reproduced in a conventional ex situ system, highlighting the transferability and importance of the results obtained in situ.
INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: This video demonstrates our endoscope-assisted microvascular decompression (MVD) technique in hemifacial spasm. A 2-cm lower retrosigmoid approach is used to reach the facial nerve exit zone. The additional use of endoscopy serves to overcome the microscopes linear axis of view on the compression site. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: A neurovascular conflict in the facial nerve exit zone is to be identified on CISS-MRI. A CT scan helps assessing the approach. Acoustic evoked potentials and facial nerve neuromonitoring including lateral spreads are required. 1. ESSENTIAL STEPS OF THE PROCEDURE: The patient is positioned supine with 45° head rotation to the contralateral side. In addition, the operating table is tilted 30° to facilitate optimal cerebellar retraction by gravity avoiding the need for cerebellar spatula. The dura is incised parallel to the sigmoid sinus. With the operating microscope, the arachnoid is dissected exposing the vestibulocochlear nerve and the lower cranial nerves. The lower cranial nerve group is exposed up to the exit from the brain stem, enabling a subfloccular approach to the facial nerve exit zone. The endoscope is used to inspect the facial nerve and to identify the compressing vessel. Microscopically, the vessel is mobilized and the nerve decompressed by shredded Teflon. 2. PITFALLS/AVOIDANCE OF COMPLICATIONS: Jugular vein compression by excessive head rotation must be avoided. Teflon placed directly onto the nerve can cause spasms itself. Opened mastoid cells are carefully sealed. VARIANTS AND INDICATIONS FOR THEIR USE: Transposition is favored over interposition. Besides shredded Teflon, a Teflon-Bridge or Teflon-Sling can be placed. 3-5The patient consented to the procedure and to the publication of her image.
Hemifacial Spasm , Microvascular Decompression Surgery , Female , Humans , Endoscopes , Facial Nerve/surgery , Hemifacial Spasm/surgery , Hemifacial Spasm/etiology , Microvascular Decompression Surgery/methods , Polytetrafluoroethylene
3D integration of III-V semiconductors with Si CMOS is highly attractive since it allows combining new functions such as photonic and analog devices with digital signal processing circuitry. Thus far, most 3D integration approaches have used epitaxial growth on Si, layer transfer by wafer bonding, or die-to-die packaging. Here we present low-temperature integration of InAs on W using Si3N4 template assisted selective area metal-organic vapor-phase epitaxy (MOVPE). Despite growth nucleation on polycrystalline W, we can obtain a high yield of single-crystalline InAs nanowires, as observed by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The nanowires exhibit a mobility of 690 cm2/(V s), a low-resistive, Ohmic electrical contact to the W film, and a resistivity which increases with diameter attributed to increased grain boundary scattering. These results demonstrate the feasibility for single-crystalline III-V back-end-of-line integration with a low thermal budget compatible with Si CMOS.
This video demonstrates the purely endoscopic gross-total resection of a third ventricle colloid cyst that is partially covered by a large thalamostriate vein. To gain an ideal approach, the initial trajectory pointed to the interventricular septum above the cyst. After the head of the caudate nucleus is passed, it is retracted laterally by the endoscopic sheath for the ideal far lateral approach to the cyst. Using a pneumatic endoscope holder enables the surgeon to perform the procedure bimanually. After complete removal of the cyst, postoperative inspection confirms the intact fornix, veins, and caudate nucleus without signs of pressure-related damage. The video can be found here: https://stream.cadmore.media/r10.3171/2023.1.FOCVID22140.
Alkalinity generation from rock weathering modulates Earth's climate at geological time scales. Although lithology is thought to dominantly control alkalinity generation globally, the role of other first-order controls appears elusive. Particularly challenging remains the discrimination of climatic and erosional influences. Based on global observations, here we uncover the role of erosion rate in governing riverine alkalinity, accompanied by areal proportion of carbonate, mean annual temperature, catchment area, and soil regolith thickness. We show that the weathering flux to the ocean will be significantly altered by climate warming as early as 2100, by up to 68% depending on the environmental conditions, constituting a sudden feedback of ocean CO2 sequestration to climate. Interestingly, warming under a low-emissions scenario will reduce terrestrial alkalinity flux from mid-latitudes (-1.6 t(bicarbonate) a-1 km-2) until the end of the century, resulting in a reduction in CO2 sequestration, but an increase (+0.5 t(bicarbonate) a-1 km-2) from mid-latitudes is likely under a high-emissions scenario, yielding an additional CO2 sink.
We explore the energetics of microwaves interacting with a double quantum dot photodiode and show wave-particle aspects in photon-assisted tunneling. The experiments show that the single-photon energy sets the relevant absorption energy in a weak-drive limit, which contrasts the strong-drive limit where the wave amplitude determines the relevant-energy scale and opens up microwave-induced bias triangles. The threshold condition between these two regimes is set by the fine-structure constant of the system. The energetics are determined here with the detuning conditions of the double dot system and stopping-potential measurements that constitute a microwave version of the photoelectric effect.
We have performed tunnel transport spectroscopy on a quantum dot (QD) molecule proximitized by a superconducting contact. In such a system, the scattering between QD spins and Bogoliubov quasiparticles leads to the formation of Yu-Shiba-Rusinov (YSR) states within the superconducting gap. In this work, we investigate interactions appearing when one- and two-electron spin states in a double-QD energetically align with the superconducting gap edge. We find that the inter-dot spin-triplet state interacts considerably stronger with the superconductor than the corresponding singlet, pointing to stronger screening. By forming a ring molecule with a significant orbital contribution to the effectiveg-factor, we observe interactions of all four spin-orbital one-electron states with the superconductor under a weak magnetic field.
BACKGROUND/AIM: Glioblastoma (GBM) is the most common and most lethal type of cancer of the central nervous system in adults. Despite aggressive treatment, which is based on surgical resection, if possible, followed by radiation and chemotherapy, a high recurrence rate and therapy resistance is observed. Thus, additional innovative therapies are urgently needed to improve the poor median survival of only 15 months. Treatment of solid tumours with non-invasive physical plasma (NIPP) represents such a novel and innovative anticancer procedure. MATERIALS AND METHODS: In this study, we investigated the effect of NIPP, an ionized argon gas, on the in vitro growth of human GBM cell lines, LN-18 and U-87 MG. Proliferation was measured by live cell count. Subsequently, proliferative factors were analysed at the level of nucleic acids (polymerase chain reaction) and proteins (western blotting). RESULTS: For both GBM lines, a treatment time-dependent decrease in growth was observed compared to controls. Additionally, NIPP treatment resulted in reduced rates of AKT serine/threonine kinase 1 (AKT1) and extracellular-regulated kinase 1/2 ERK1/2 expression, whereas expression of p21, proliferating cell nuclear antigen, and heat-shock proteins 90α and 90ß was not affected. In both cell lines, a strong increase in expression of tumour-suppressive microRNA-1 (miR-1) was detected after exposure to NIPP. CONCLUSION: Our results demonstrated that NIPP is able to efficiently attenuate growth of GBM cells and suggest AKT1, ERK1/2 and miR-1 to be pivotal factors of NIPP-modulated cellular signalling. Translated into the clinical setting, NIPP may represent a promising option for the treatment of GBM.
Brain Neoplasms , Glioblastoma , MicroRNAs , Humans , Glioblastoma/drug therapy , Brain Neoplasms/drug therapy , Signal Transduction , MicroRNAs/therapeutic use , Proteins , Cell Line, Tumor , Cell Proliferation
In this Letter, we manipulate the phase shift of a Josephson junction using a parallel double quantum dot (QD). By employing a superconducting quantum interference device, we determine how orbital hybridization and detuning affect the current-phase relation in the Coulomb blockade regime. For weak hybridization between the QDs, we find π junction characteristics if at least one QD has an unpaired electron. Notably the critical current is higher when both QDs have an odd electron occupation. By increasing the inter-QD hybridization the critical current is reduced, until eventually a π-0 transition occurs. A similar transition appears when detuning the QD levels at finite hybridization. Based on a zero-bandwidth model, we argue that both cases of phase-shift transitions can be understood considering an increased weight of states with a double occupancy in the ground state and with the Cooper pair transport dominated by local Andreev reflection.
In this work, we demonstrate the performance of a silicon-compatible, high-performance, and self-powered photodetector. A wide detection range from visible (405 nm) to near-infrared (1550 nm) light was enabled by the vertical p-n heterojunction between the p-type antimony telluride (Sb2Te3) thin film and the n-type silicon (Si) substrates. A Sb2Te3 film with a good crystal quality, low density of extended defects, proper stoichiometry, p-type nature, and excellent uniformity across a 4 in. wafer was achieved by atomic layer deposition at 80 °C using (Et3Si)2Te and SbCl3 as precursors. The processed photodetectors have a low dark current (â¼20 pA), a high responsivity of (â¼4.3 A/W at 405 nm and â¼150 mA/W at 1550 nm), a peak detectivity of â¼1.65 × 1014 Jones, and a quick rise time of â¼98 µs under zero bias voltage. Density functional theory calculations reveal a narrow, near-direct, type-II band gap at the heterointerface that supports a strong built-in electric field leading to efficient separation of the photogenerated carriers. The devices have long-term air stability and efficient switching behavior even at elevated temperatures. These high-performance and self-powered p-Sb2Te3/n-Si heterojunction photodetectors have immense potential to become reliable technological building blocks for a plethora of innovative applications in next-generation optoelectronics, silicon-photonics, chip-level sensing, and detection.
In this work we demonstrate a two-fold selectivity control of InAs shells grown on crystal phase and morphology engineered GaAs nanowire (NW) core templates. This selectivity occurs driven by differences in surface energies of the NW core facets. The occurrence of the different facets itself is controlled by either forming different crystal phases or additional tuning of the core NW morphology. First, in order to study the crystal phase selectivity, GaAs NW cores with an engineered crystal phase in the axial direction were employed. A crystal phase selective growth of InAs on GaAs was found for high growth rates and short growth times. Secondly, the facet-dependant selectivity of InAs growth was studied on crystal phase controlled GaAs cores which were additionally morphology-tuned by homoepitaxial overgrowth. Following this route, the original hexagonal cores with {110} sidewalls were converted into triangular truncated NWs with ridges and predominantly {112}B facets. By precisely tuning the growth parameters, the growth of InAs is promoted over the ridges and reduced over the {112}B facets with indications of also preserving the crystal phase selectivity. In all cases (different crystal phase and facet termination), selectivity is lost for extended growth times, thus, limiting the total thickness of the shell grown under selective conditions. To overcome this issue we propose a 2-step growth approach, combining a high growth rate step followed by a low growth rate step. The control over the thickness of the InAs shells while maintaining the selectivity is demonstrated by means of a detailed transmission electron microscopy analysis. This proposed 2-step growth approach enables new functionalities in 1-D structures formed by using bottom-up techniques, with a high degree of control over shell thickness and deposition selectivity.
We study experimentally work fluctuations in a Szilard engine that extracts work from information encoded as the occupancy of an electron level in a semiconductor quantum dot. We show that as the average work extracted per bit of information increases toward the Landauer limit k_{B}Tln2, the work fluctuations decrease in accordance with the work fluctuation-dissipation relation. We compare the results to a protocol without measurement and feedback and show that when no information is used, the work output and fluctuations vanish simultaneously, contrasting the information-to-energy conversion case where increasing amount of work is produced with decreasing fluctuations. Our study highlights the importance of fluctuations in the design of information-to-work conversion processes.
BACKGROUND: Microvascular decompression (MVD) success rates exceed 90% in hemifacial spasm (HFS). However, postoperative recovery patterns and durations are variable. OBJECTIVE: We aim to study factors that might influence the postoperative patterns and duration needed until final recovery. METHOD: Only patients following de-novo MVD with a minimum follow-up of 6 months were included. Overall trend of recovery was modeled. Patients were grouped according to recognizable clinical recovery patterns. Uni- and multivariable analyses were used to identify the factors affecting allocation to the identified patterns and time needed to final recovery. RESULTS: A total of 323 (92.6%) patients had > 90% symptom improvement, and 269 (77.1%) patients had complete resolution at the last follow-up. The overall trend of recovery showed steep remission within the first 6 months, followed by relapse peaking around 8 months with a second remission ~ 16 months. Five main recovery patterns were identified. Pattern analysis showed that evident proximal indentation of the facial nerve at root exit zone (REZ), males and facial palsy are associated with earlier recovery at multivariable and univariable levels. anterior inferior cerebellar artery (AICA), AICA/vertebral artery compressions and shorter disease durations are related to immediate resolution of the symptoms only on the univariable level. Time analysis showed that proximal indentation (vs. distal indentation), males and facial palsy witnessed significantly earlier recoveries. CONCLUSION: Our main finding is that in contrast to peripheral indentation, proximal indentation of the facial nerve at REZ is associated with earlier recovery. Postoperative facial palsy and AICA compressions are associated with earlier recoveries. We recommend a minimum of 1 year before evaluating the final outcome of MVD for HFS.
Facial Paralysis , Hemifacial Spasm , Microvascular Decompression Surgery , Facial Nerve/surgery , Facial Paralysis/surgery , Hemifacial Spasm/surgery , Humans , Male , Retrospective Studies , Treatment Outcome
Brain stimulation is a core method in neuroscience. Numerous non-invasive brain stimulation (NIBS) techniques are currently in use in basic and clinical research, and recent advances promise the ability to non-invasively access deep brain structures. While encouraging, there is a surprising gap in our understanding of precisely how NIBS perturbs neural activity throughout an interconnected network, and how such perturbed neural activity ultimately links to behaviour. In this review, we will consider why non-human primate (NHP) models of NIBS are ideally situated to address this gap in knowledge, and why the oculomotor network that moves our line of sight offers a particularly valuable platform in which to empirically test hypothesis regarding NIBS-induced changes in brain and behaviour. NHP models of NIBS will enable investigation of the complex, dynamic effects of brain stimulation across multiple hierarchically interconnected brain areas, networks, and effectors. By establishing such links between brain and behavioural output, work in NHPs can help optimize experimental and therapeutic approaches, improve NIBS efficacy, and reduce side-effects of NIBS.
Transcranial Direct Current Stimulation , Transcranial Magnetic Stimulation , Animals , Brain/physiology , Eye Movements , Primates , Transcranial Direct Current Stimulation/methods , Transcranial Magnetic Stimulation/methods
We experimentally investigate the properties of one-dimensional quantum rings that form near the surface of nanowire quantum dots. In agreement with theoretical predictions, we observe the appearance of forbidden gaps in the evolution of states in a magnetic field as the symmetry of a quantum ring is reduced. For a twofold symmetry, our experiments confirm that orbital states are grouped pairwise. Here, a π-phase shift can be introduced in the Aharonov-Bohm relation by controlling the relative orbital parity using an electric field. Studying rings with higher symmetry, we note exceptionally large orbital contributions to the effective g-factor (up to 300), which are many times higher than those previously reported. These findings show that the properties of a phase-coherent system can be significantly altered by the nanostructure symmetry and its interplay with wave function parity.
In this Letter, we explore the use of thermodynamic length to improve the performance of experimental protocols. In particular, we implement Landauer erasure on a driven electron level in a semiconductor quantum dot, and compare the standard protocol in which the energy is increased linearly in time with the one coming from geometric optimization. The latter is obtained by choosing a suitable metric structure, whose geodesics correspond to optimal finite-time thermodynamic protocols in the slow driving regime. We show experimentally that geodesic drivings minimize dissipation for slow protocols, with a bigger improvement as one approaches perfect erasure. Moreover, the geometric approach also leads to smaller dissipation even when the time of the protocol becomes comparable with the equilibration timescale of the system, i.e., away from the slow driving regime. Our results also illustrate, in a single-electron device, a fundamental principle of thermodynamic geometry: optimal finite-time thermodynamic protocols are those with constant dissipation rate along the process.
