Design study of a micro illumination platform based on GaN microLED arrays.

The design study of a micro illumination tool based on GaN microLED arrays is presented. The high spatio-temporal resolution and the capability of generating fully customized optical patterns that characterize the proposed platform would enable the manipulation of biological systems, e.g., for optogenetics applications. Based on ray tracing simulations, the design aspects that mainly affect the device performance have been identified, and the related structural parameters have been optimized to improve the extraction efficiency and the spatial resolution of the resulting light patterns. Assuming that the device is a bottom emitter, and the light is extracted from the n-side, the presence of mesa-structures on the p-side of the GaN layer can affect both the efficiency and the resolution, being optimized for different values of the mesa-side inclination angle. The full width at half maximum (FWHM) of the extracted spots is mainly determined by the substrate thickness, and the relation between the FWHM and the array pitch represents a criterion to define the resolution. Namely, when F W H M

Optical design of InGaN/GaN nanoLED arrays on a chip: toward: highly resolved illumination.

The physical laws of diffraction limit the spatial resolution of optical systems. In contrary to most superresolution microscopy approaches used today, in our novel idea we are aiming to overcome this limit by developing a spatially resolved illumination source based on semiconductor nanoscale light emitting diode (nanoLED) arrays with individual pixel control. We present and discuss the results of optical simulations performed for such nanoLED emitter arrays and analyze the theoretical limits of this approach. As possible designs we study arrays of GaN nanofins and nanorods (obtained by etching nanofin arrays), with InGaN/GaN multi quantum wells embedded as active regions. We find that a suitable choice of the array dimensions leads to a reasonably directed light output and concentration of the optical power in the near field around an activated pixel. As a consequence, the spatial resolution for this type of microscopy should only be limited by the pixel pitch, and no longer by the optical diffraction. Realization of optimized nanoLED arrays has a potential to open new field of chip based superresolution microscopy, making super-high spatial resolution ubiquitously available.

Anatomical and histological study of the deep neck fasciae: does the alar fascia exist?

PURPOSE: The aim of this study was to determine whether the alar fascia is a distinct layer of the deep cervical neck fasciae. The present study also aimed to elucidate the anatomical limits of this fascia. METHODS: Neck dissections of ten adult cadavers were performed, layer by layer, in the retropharyngeal region, under a powered operating microscope. Detailed dissections revealed the anatomical limits of the deep neck fasciae. Histological descriptions were also performed on large tissue samples collected from three cervical dissections. RESULTS: In the ten dissections, three layers of fascia were identified and dissected in the retropharyngeal region: a visceral fascia, a prevertebral fascia and an alar fascia. The alar fascia appeared like a connecting band derivative of the visceral fascia, between both vascular sheaths. It fused completely with the visceral fascia anteriorly at the level of T2 and with the prevertebral fascia posteriorly at the level of C1. No sagittal connection between the visceral fascia and the prevertebral fascia was identified. The stained histological sections confirmed the presence of the visceral and prevertebral fasciae at the oropharyngeal level, with a third intermediate layer closely connected with the visceral fascia. CONCLUSION: The alar fascia is a layer of the cervical neck fascia connected with the visceral fascia from C1 to T2 levels. The anatomical limits of this alar fascia and its relationships with the internal carotid artery are important in the surgical management and the prognosis of deep neck infections and retropharyngeal lymph node metastases.

Superior laryngeal nerve in thyroid surgery: anatomical identification and monitoring.

The aim of this study was to validate a procedure to identify and preserve the external branch of the superior laryngeal nerve (EBSLN) during thyroid surgery. The present study also aimed to analyze the EBSLN and the vagus nerve activities after stimulation and demonstrate an operative association between all the laryngeal muscles. Dissection of the cervical region was performed bilaterally in four adult cadavers. In a second step, 144 patients undergoing total thyroidectomy were included. Intraoperative stimulations of the cervical vagus nerve and the EBSLN in the sternothyroid-laryngeal triangle were performed bilaterally. Potentials in the thyroarytenoid muscle and the cricothyroid muscle were registered on each side using the NIM3 Medtronic System. EBSLN was identified according to Cernea's classification as type 1 in 62.5%, type 2a in 25%, and type 2b in 12.5% of cadaver's dissection. According to Friedman's classification, 50% of EBSLN were classified type 1, 25% type 2 and 25% type 3. The EBSLN was identified in 267 cases out of 288 peroperative dissections (92.7%). Direct stimulation (1 mA) of this branch led to a recordable contraction of the cricothyroid muscle with a mean latency of 1.42 ± 0.66 ms on the right side and 1.43 ± 0.61 ms on the left side. The stimulation of the EBSLN also led to a recordable contraction of the thyroarytenoid muscle in 211 cases (73.3%) with the same latencies. A contraction of the cricothyroid muscle was also recorded when the vagus nerve was stimulated in 219 cases (76.0%). The sole visual identification of the EBSLN during thyroid surgery is not a reliable method to prevent nerve injury. Direct stimulation of the EBSLN in the sternothyroid-laryngeal triangle is a simple and rapid procedure to detect and preserve the nerve during surgery. Functional associations between vagus nerve and EBSLN in laryngeal muscles' contractions were also identified.

[The parapharyngeal adipose corpus: Surgical anatomy and imaging]. / Le corps adipeux parapharyngé : anatomie chirurgicale et imagerie.

The aim of this study is to define the parapharyngeal adiposis corpus (PAC) and its anatomical relationships originally described by P. Sebileau in 1892 to assess the potential clinical implications. MATERIALS AND METHODS: Seven frozen fresh cadavers were used, 3 of which after injection of latex neoprene colored in cervicocephalic arterial network. A MRI was performed in 10 patients without cervical pathology. The analysis was done on the frontal and transverse T1-weighted sections. RESULTS: The PAC, which is a yellowish fat formation, fills the paratonsillar space. It measures an average of 4.8cm (4.5 to 5.2cm) in length and 1.2cm (1.1 to 1.5cm) for subjects of varying size and sex. Its arterial supply is mainly provided by the ascending palatine artery, an early branch of the facial artery. A left-right symmetry was found on MRI analyses regardless of sex or age. It is found in all the medial and ventral cases on the pharyngeal extension of the parotid gland in homogeneous hyperintense T1. CONCLUSION: The PAC is a constant fat structure. Its vascularization depends mainly on the ascending palatine artery. Through its association with fatty peripharyngeal space, it could be a functionally sliding space. In imaging, it may be helpful in the interpretation of images of the pharyngeal extension of the parotid gland tumors.

Topographical and functional anatomy of trapezius muscle innervation by spinal accessory nerve and C2 to C4 nerves of cervical plexus.

The aim of this study was to determine the existence and the frequency of communicating branches between the spinal accessory nerve (SAN) and the C2, C3 and C4 roots of the cervical plexus. The present study also aimed to elucidate whether these branches contain motor fibers or not. Dissection of the cervical region was performed on twelve adult cadavers. A powered operating microscope was necessary to dissect the SAN and its branches and also to dissect C2, C3 and C4 nerve branches. In a second step, data from 13 patients who underwent 25 modified neck dissections under trapezius muscle's monitoring were collected. At the end of surgery, intraoperative stimulation on the SAN, C2, C3 and C4 nerve branches was performed. Registered potentials in the three parts of the trapezius muscle, using the NIM Medtronic system, were analyzed. During cadaver dissection, 18 (78 %) communicating branches were identified between the SAN and C2, 11 (48 %) between the SAN and C3, 12 (52 %) between the SAN and C4. Intraoperative stimulation of the SAN and its branch for the trapezius muscle provided a significant electroneurographic response in the three parts of the trapezius muscle in all subjects. Intraoperative stimulation of C3 led to recordable contractions of the trapezius muscle in 5 (20 %) modified neck surgeries, stimulation of C4 led to recordable contractions during 5 (20 %) modified neck dissections. One case of contraction was recorded after intraoperative stimulation of C2 (7 %). Although we were able to identify at least one communicating branch between the SAN and the roots of the cervical plexus in each cadaver dissection, the cervical plexus is not always involved in trapezius motor innervation. Intraoperative electroneurography demonstrated that a motor input from the cervical plexus to the trapezius muscle was provided in only 32 % of cases. Therefore, SAN trunk and C3-C4 roots should be carefully preserved during modified neck dissection to protect trapezius and shoulder functions.

A transfer hamiltonian model for devices based on quantum dot arrays.

We present a model of electron transport through a random distribution of interacting quantum dots embedded in a dielectric matrix to simulate realistic devices. The method underlying the model depends only on fundamental parameters of the system and it is based on the Transfer Hamiltonian approach. A set of noncoherent rate equations can be written and the interaction between the quantum dots and between the quantum dots and the electrodes is introduced by transition rates and capacitive couplings. A realistic modelization of the capacitive couplings, the transmission coefficients, the electron/hole tunneling currents, and the density of states of each quantum dot have been taken into account. The effects of the local potential are computed within the self-consistent field regime. While the description of the theoretical framework is kept as general as possible, two specific prototypical devices, an arbitrary array of quantum dots embedded in a matrix insulator and a transistor device based on quantum dots, are used to illustrate the kind of unique insight that numerical simulations based on the theory are able to provide.

Surgical anatomy of the styloid muscles and the extracranial glossopharyngeal nerve.

PURPOSE: The purpose of the study was to determine the relationships between the extracranial glossopharyngeal (IX) nerve and the muscles of the styloid diaphragm. In humans, the IX nerve is a hidden retrostyloid nerve which plays a critical role notably in swallowing and has to be preserved during infratemporal fossa and parapharyngeal spaces surgical procedures. METHOD: In ten adult heads from cadavers (20 sides) fixed in formalin, dissection of the extracranial IX nerve was performed under operating microscope with special attention given to the relationships between this nerve and the styloid muscles of the styloid diaphragm. The three styloid muscles delimit three triangular intermuscular intervals which were each thoroughly explored. Different osseous landmarks were investigated for easy nerve location. RESULTS: The styloid process (SP) is the main superior osseous landmark for the three muscles of the styloid diaphragm. The stylohyoid muscle (SHM) is anteromedially located to the posterior belly of the digastric muscle. The styloglossus muscle (SGM) is medial and anterior to the SHM. The stylopharyngeal muscle (SPM) is the most vertical and medial of the three styloid muscles. It courses from the medial surface of the SP in a deep plane hidden between the SHM and the SGM. The extracranial IX nerve turns around the SPM superiorly with a vertical segment posterior to the SPM and inferiorly with a horizontal segment lateral to the SPM. The meeting point of the two segments of the IX nerve is about 10 mm anteriorly located from the transverse process of the atlas. The external carotid artery and some of its branches lie in contact with the lateral side of the IX nerve. CONCLUSION: Such relationships between the extracranial IX nerve, the styloid muscles and the transverse process of the atlas should be appreciated by clinician who treats patients with stylohyoid complex syndromes and by the surgeon for the parapharyngeal spaces approach.

Fluorescence Multi-Detection Device Using a Lensless Matrix Addressable microLED Array.

A Point-of-Care system for molecular diagnosis (PoC-MD) is described, combining GaN and CMOS chips. The device is a micro-system for fluorescence measurements, capable of analyzing both intensity and lifetime. It consists of a hybrid micro-structure based on a 32 × 32 matrix addressable GaN microLED array, with square LEDs of 50 µm edge length and 100 µm pitch, with an underneath wire bonded custom chip integrating their drivers and placed face-to-face to an array of 16 × 16 single-photon avalanche diodes (SPADs) CMOS. This approach replaces instrumentation based on lasers, bulky optical components, and discrete electronics with a full hybrid micro-system, enabling measurements on 32 × 32 spots. The reported system is suitable for long lifetime (>10 ns) fluorophores with a limit of detection ~1/4 µM. Proof-of-concept measurements of streptavidin conjugate Qdot™ 605 and Amino PEG Qdot™ 705 are demonstrated, along with the device ability to detect both fluorophores in the same measurement.

Positive predictive values of ultrasound-guided fine-needle aspiration with parathyroid hormone assay and Tc-99m sestamibi scintigraphy in sporadic primary hyperparathyroidism.

OBJECTIVES: Ultrasonography (US) and Tc-99m sestamibi scintigraphy (SS) are usually performed as preoperative imaging modalities for patients with sporadic primary hyperparathyroidism (SPHP). Fine-needle aspiration (FNA) under US guidance for parathyroid hormone (PH) assay can enhance the diagnostic accuracy of US. The main aim of the present study was to compare positive predictive values between US-FNA and SS. The secondary aim was to draw up a decision-tree for FNA and SS. METHODS: The single-center retrospective study included patients with previously non-operated SPHP. They underwent US-guided FNA, PET-CT SS, and 18 F-choline scintigraphy if the first two methods were inconclusive. PH washout level was considered pathological when greater than the serum PH level. Postoperative histology data were correlated to imaging data. RESULTS: In total, 117 patients were included, with a mean age of 64 years (range, 26-89 years). A single adenoma was identified on pathology in 101 patients (89%). FNA findings were pathologic for 64 patients (55%), with a mean PH level of 2,604ng/L [range, 585-9,074ng/L], higher than the serum level of 179ng/L [range, 60-1,000ng/L]. US-guided FNA showed sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of respectively 72%, 92%, 99% and 28%, compared to 89%, 42%, 93% and 32% for SS. The rate of error in locating the parathyroid gland was 8% for US-guided FNA versus 12% for SS. Comparison of the two methods showed better sensitivity for SS (P=0.0052) and better specificity for FNA (P=0.0143), with no significant difference in PPV or NPV. 18 F-choline scintigraphy detected the hyperfunctioning parathyroid in 11 out of the 15 patients. CONCLUSION: PPV did not significantly differ between FNA and SS. US-guided FNA performed by an experienced operator could be a simple first-line method for more than 50% of patients with non-operated SPHP, with 99% PPV. In case of negative or doubtful FNA findings, SS can be performed in second line.

Management of the neck in the setting of definitive chemoradiation: is there a consensus? A GETTEC study.

BACKGROUND: The management of the neck remains controversial in the definitive chemoradiation setting of advanced N2-3 head and neck squamous cell carcinoma. Most published data favor omission of neck dissection (ND) after complete response for N2-3 or selective ND for residual disease METHODS: We studied the patterns of care in the French-Belgian Groupe d'Etude des Tumeurs de la Tête Et du Cou (GETTEC) through a questionnaire-based survey. RESULTS: Eighteen percent of institutions never performed up-front ND, 20% rarely, 40% sometimes, 14% often, and 8% systematically. Induction chemotherapy was indicated in 30% of the cases, and most ND were performed either between induction and radiation or after chemoradiation for residual disease. Response to chemoradiation was assessed by computed tomographic scan and positron emission tomography in 72% of cases. Selective ND was more common than radical ND. CONCLUSIONS: Omission of ND based on computed tomographic scan and positron emission tomography-based complete response to chemoradiation is the most common strategy for advanced nodal disease among centers. However, neck management strategies vary among institutions, and some institutions continue advocating systematic ND before irradiation. The new treatment options and the changing epidemiology, namely docetaxel-based induction chemotherapy and human papilloma virus-related head and neck squamous cell carcinoma having better response profiles and prognosis, are adding to the nonconsensual approach. The best therapeutic index in terms of neck management remains to be defined in this evolving context.

Morphological and functional asymmetry of the human recurrent laryngeal nerve.

PURPOSE: The aim of the current study was to analyze some parameters that are involved in nerve conduction in the right and left recurrent laryngeal nerves (RLNs) in humans. We have studied two morphological parameters such as the length of the two nerves, and the total intraperineural area (TIPA) from necropsies, and one functional parameter such as the latency of the thyroarytenoid muscle from operated patients. METHODS: The morphological parameters of six white female adult cadavers were analyzed. The RLNs were totally removed on both sides with the vagus nerve from their origin to the entrance in the larynx at the cricothyroid joint. The lengths were measured with the help of a digitalized caliper. Selected sections were obtained from each third of the RLNs for histological analysis. The TIPA was estimated at each selected level using digitized images of nerve sections and a manual micrometer. All the measurements were carried out by specialists in histology. The intraoperative vagal nerve stimulations were conducted using the NIM3 Medtronic(®) monitoring system (Medtronic Xomed Inc., Jacksonville, FL, USA) in ten adult patients without laryngeal or nervous disease during thyroid gland surgery. The evocated laryngeal electromyography was performed with the Medtronic bipolar needle electrode directly inserted into the thyroarytenoid muscle. The direct vagal nerve stimulation was achieved with the Medtronic stimulation from 0.5 to 1 mA. The latency of the thyroarytenoid muscle was recorded on the NIM-response monitor. RESULTS: The mean lengths of the left and right RLNs were, respectively, 136.6 and 75.0 mm with a mean difference of 61.6 mm (range 50-75 mm). The quantitative comparison of the TIPA between proximal segments of the left and right RLN showed no significant difference. The distal and proximal TIPA ratio demonstrated differences between the left and right RLN, respectively, 53.76 and 38.88 % without any statistical meaning. The comparison of the TIPA of the distal segments of the RLNs showed no significant difference. The intraoperative vagal nerve stimulation (0.5 and 1 mA) displayed a mean latency of the right and left thyroarytenoid muscle, respectively, of 3.55-3.68 and 5.90-5.98 ms with a mean difference of 2.35-2.30 ms (range 1.75-3.30 ms). CONCLUSION: If length and latency asymmetry of the right and left RLNs in humans can be demonstrated, the synchronicity of the vocal folds requiring precise controlled variations within intrinsic laryngeal muscles needs further investigations.

Implementing a Cancer Fast-track Programme between primary and specialised care in Catalonia (Spain): a mixed methods study.

BACKGROUND: The Cancer Fast-track Programme's aim was to reduce the time that elapsed between well-founded suspicion of breast, colorectal and lung cancer and the start of initial treatment in Catalonia (Spain). We sought to analyse its implementation and overall effectiveness. METHODS: A quantitative analysis of the programme was performed using data generated by the hospitals on the basis of seven fast-track monitoring indicators for the period 2006-2009. In addition, we conducted a qualitative study, based on 83 semistructured interviews with primary and specialised health professionals and health administrators, to obtain their perception of the programme's implementation. RESULTS: About half of all new patients with breast, lung or colorectal cancer were diagnosed via the fast track, though the cancer detection rate declined across the period. Mean time from detection of suspected cancer in primary care to start of initial treatment was 32 days for breast, 30 for colorectal and 37 for lung cancer (2009). Professionals associated with the implementation of the programme showed that general practitioners faced with suspicion of cancer had changed their conduct with the aim of preventing lags. Furthermore, hospitals were found to have pursued three specific implementation strategies (top-down, consensus-based and participatory), which made for the cohesion and sustainability of the circuits. CONCLUSION: The programme has contributed to speeding up diagnostic assessment and treatment of patients with suspicion of cancer, and to clarifying the patient pathway between primary and specialised care.

[Computed tomography of the normal and pathologic temporal bone]. / Anatomie tomodensitométrique de l'oreille normale et malformée.

High-resolution computed tomography scanning (CT) allows depiction of microanatomic structures of the temporal bone. CT is useful for detecting several pathologic conditions of the temporal bone such as congenital malformations, particularly in young children with sensorineural hearing loss. Some external, middle and inner ear structures are difficult to evaluate. The objective of this study has been to provide the key planes in coronal and axial planes (five coronal planes and three axial planes) but also with oblique planes reconstruction (two planes) for normal temporal bones evaluation. These standardized planes help to improve visualization of the main congenital malformations. Identification of obvious morphogenetic malformations (Michel aplasia, Mondini deformity….) is not difficult. However, less severe dysplasia may be missed or normal micro anatomic structures in newborn misreaded.

Thyroid surgery under hypnosis: A 50-case series.

OBJECTIVES: The study objective was to compare patient satisfaction after thyroid lobo-isthmectomy under hypnoanesthesia versus general anesthesia. METHODS: A retrospective study included 100 patients undergoing lobo-isthmectomy. A group of 50 patients under hypnoanesthesia was compared to a control group of 50 patients under general anesthesia. Satisfaction was assessed on questionnaire between three and six months after surgery. We also compared secondary criteria: procedure time, blood loss, intraoperative comfort, postoperative pain, postoperative complications and time to resumption of daily activities. RESULTS: Our study showed good overall satisfaction in patients operated under hypnoanesthesia, for equivalent operative safety and complications rate compared to general anesthesia. For comparable analgesia, postoperative pain was lower, but not significantly, in the Hypnosis group, while the rate of nausea and vomiting was significantly lower (p<0.05). Postoperative convalescence was shorter in the Hypnosis group: 3.7 versus 9.2 days (p<0.001). CONCLUSION: In thyroid surgery, hypnoanesthesia has real advantages over general anesthesia in that it places the patient at the center of the care team's attention. His or her active participation is essential during the process, bringing a new dimension to care, beneficial for the patient. However, it must be reserved for minimally invasive procedures in which organization is anticipated in full collaboration within teams that are willing and experienced.

Endonasal endoscopic approach to the pterygopalatine and infratemporal fossae.

The pterygopalatine fossa and infratemporal fossa are spaces located under the skull base, housing important neurovascular structures. Surgical access to these spaces is challenging because of their deep location and complex anatomy. Their surgical access has been classically carried out through multiple craniofacial approaches until the advent of endoscopic endonasal surgery at the end of the XXth century. Our goal is to describe the transmaxillary-transsphenoidal-transpterygoid approach to the pterygopalatine and infratemporal fossae through endonasal endoscopic surgery based on anatomo-surgical dissection and an illustrative clinical case. We conclude that after careful radiologic evaluation of the feasibility of this technique, the endonasal endoscopic access to these spaces for tumor resection is efficient with reduced surgical morbidities. The endonasal approach is versatile and can be fashioned according to the nature and extent of the lesion.

Plasmon expedited response time and enhanced response in gold nanoparticles-decorated zinc oxide nanowire-based nitrogen dioxide gas sensor at room temperature.

A highly sensitive and rapidly responsive nitrogen dioxide (NO2) gas sensor based on gold (Au) nanoparticles (NPs)-decorated zinc oxide (ZnO) nanowires (NWs) is presented. The Au NPs decoration was conducted onto ZnO NWs with and without a (3-aminopropyl)triethoxysilane (APTES) layer on their surface by using the electrostatic force. The samples without the APTES layer exhibited high NO2 gas sensitivity (i.e. expedited response time and enhanced gas response) due to localized surface plasmon resonance (LSPR) of the Au NPs; in particular, the NO2 gas response and the response time were increased by three times and shortened by 86%, respectively, compared with the undecorated ZnO NWs. The presence of the APTES layer improved the Au NPs attachment, but hindering the gas adsorption on the ZnO NWs surface, as proven by the observed photocurrent and gas response. Our findings imply that the response time of semiconductor gas sensors can be remarkably expedited by the LSPR effect, which is useful for developing practical gas sensors.

Bidimensional versus tridimensional oxygen vacancy diffusion in SnO(2-x) under different gas environments.

Metal oxides present oxygen defects that induce different chemical and physical properties. Experiments performed in SnO(2-x) sensors show that the dynamics of these vacancies are strongly affected by the presence of different gases in the environment. Experimentally, the electrical resistance of individual metal oxide SnO(2-x) nanowires shows modulation: when the environment is oxygen rich long term drifts (hours) are observed indicating extended vacancy dynamics. Instead, if CO is present, drifts disappear in minutes. Density functional theory indicates that changes in resistance follow the extension of reoxidation. For oxygen-poor environments, oxygen vacancy excorporation and healing are confined to the near-surface layer of SnO(2-x) (bidimensional or near-surface diffusion), and completed in short times. Under oxygen-rich conditions, tridimensional diffusion of oxygen vacancies towards the surface takes place at room temperature. In this case, a push-pull mechanism allows bulk-to-surface diffusion and as a consequence resistance drifts are longer and the vacancy quenching is more extensive.

Intraoperative neuromonitoring by vagus nerve stimulation in thyroid surgery: Clinical assessment of recurrent and superior laryngeal nerves.

Intraoperative neuromonitoring of the laryngeal nerves during thyroidectomy is a reliable method to assess nerve function. After identification of the cricothyroid ligament, a bipolar electrode is selectively inserted through the ligament into the thyroarytenoid muscle (TAM) and cricothyroid muscle (CTM). Vagus nerve stimulation then allows precise monitoring of the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve (EBSLN) in the TAM and CTM, respectively. A significant muscle response (greater than 100µV) is 100% predictive of preserved laryngeal mobility, while the absence of a muscle response is 70% predictive of vocal fold paralysis with 100% sensitivity and 98% specificity. A significant thyroarytenoid muscle response is only recorded ipsilateral to the stimulation with a shorter latency on the right side. A concomitant TAM and CTM response to vagus nerve stimulation or EBSLN stimulation is observed in more than 70% of cases.