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Premixed flame kernels exposed to a mean expanding supersonic channel flow are examined using experiments and large-eddy simulations. Four cases, spanning three Mach numbers and two equivalence ratios, are explored. Numerical results are processed similarly to and compared with experimental data. Accuracy is assessed by comparing the numerically resolved flow field, flame growth, and internal flame structure with experimental data. Evolution of the flame topology, ascertained using these combined studies, confirms that the flame kernel morphs into a reacting vortex ring upon interaction with the supersonic mean flow expansion. The vortex ring topology assessment shows potentially significant errors in the turbulent flame speed based on line of sight (LOS) measurements. Modifications to the flame speed to correct the error associated with line of sight measurements are proposed. Two turbulent flame speed scalings are investigated: one with the RMS turbulent velocity, u ′, and the other with the vortex propagation velocity, U T. It is shown that u ′ fails to collapse the flame speed data but U T scaling does collapse the data from all four cases and produces a nearly linear scaling regime. This finding suggests turbulence plays a secondary role to the hydrodynamic instability in this particular problem. The conditions for displacement and consumption speed equivalency are explored further and it is found that the nature of the diagnostic used (LOS, planar, volumetric) and the progress variable isocontour measured play important roles and should be considered during interpretation of experimental data. [ABSTRACT FROM AUTHOR]

Computational predictions of measures for macroscopic material attributes from the microstructure scale is a fundamental challenge in materials science. Data transfer across scales and physics-based models plays a central role in this highly material-specific process. Here, we present an approach for computationally establishing the probabilistic shock-to-detonation transition (SDT) threshold or "pop plot" (PP, the relation between run-to-detonation distance and applied pressure) of polymer-bonded explosives (PBXs) from three-dimensional (3D) simulations. The approach takes respective advantages of multiphysics Lagrangian and Eulerian modeling frameworks. The combined Lagrangian and Eulerian simulations provide an explicit account of 3D heterogeneous material microstructure at sizes up to tens of mm, mechanisms for the development of hotspots, and the coupled mechanical-thermal-chemical-transport processes which underlie the behaviors being predicted. Data transfers in the form of hotspot intensity fields from the Lagrangian simulations to the Eulerian simulations link the two frameworks. To capture the fundamental nature of the multiphysics processes, the source, and the propagation of the stochastic variations in material behavior, a 3D statistically equivalent microstructure sample set (SEMSS) is designed and used. The approach facilitates an efficient quantification of the probabilistic macroscopic detonation thresholds, leading to an analytical expression for the PP that accounts for both the microstructure effects and uncertainties. The material system modeled tracks the properties of PBX 9501 and the loading conditions studied involve shock pressure Ps in the range of 11–15 GPa. The results are in good agreement with available experimental data. [ABSTRACT FROM AUTHOR]

Venous malformations are low flow endothelial malformations with aberrant and ectatic venous channels. They are defects in vascular growth which causes functional and cosmetic impairment. Gradual growth in size of the lesion occurs due to venous congestion or thrombosis. Venous malformations in parapharyngeal space are a rare entity and are difficult to diagnose. Case Report. 13 year old boy presented with a history of hyposmia and progressive difficulty in breathing for a duration of 2.5 years. MRI face and neck with contrast showed a 4.5 × 4.3x3.6 cm lesion in the left parapharyngeal space. CT angiogram of brain and neck demonstrated a heterogeneously enhancing mass in the left parapharyngeal region. PET scan illustrated an ill-defined mass in the left pre styloid parapharyngeal space. Biopsy from the lesion showed features consistent with venolymphatic malformation. Flexible laryngoscopy showed a bulge over the left soft palate region with narrowing of nasopharyngeal lumen. Patient underwent transoral robotic surgery for complete excision of the mass. Post-operative period was uneventful. He has been on follow up for the past 1 year with no evidence of any residual or recurrent disease. Venolymphatic malformation is a rare lesion in the parapharyngeal space which is difficult to diagnose pre operatively. Surgical excision is the preferred modality of treatment for deep seated lesions in the parapharyngeal space. The advent of transoral robotic surgery have reduced the morbidity and improved clearance for such cases. [ABSTRACT FROM AUTHOR]

Introduction: Chondrosarcomas are rare malignancies of the cartilage and myxoid chondrosarcoma is its variant which commonly occurs in soft tissue of extremities. Extraskeletal chondrosarcoma is a rare malignant neoplasm of bone or soft tissue origin and is characterized by the presence of spindle cells admixed with well differentiated cartilage or chondroid stroma. They are mostly radioresistant tumours and surgical resections with adequate margins is considered as the ideal treatment modality with adjuvant radiotherapy in high grade tumours and add on chemotherapy, in case of presence of poor prognostic factors. Case Report: A 51-year-old diabetic, hypertensive female patient presented to our outpatient department with difficulty in chewing food for a duration of 6 months. On clinical examination, she had an ulceroproliferative growth involving right lower alveolus and floor of mouth. MRI face and neck with contrast showed a 4.1 × 2.9 × 4.5 cm lesion involving right lower alveolus extending to floor of mouth. Biopsy showed features of extraskeletal myxoid chondrosarcoma. She was planned for upfront surgery (Right composite resection with modified radical neck dissection with free fibula flap). Patient was stable post-surgery and was discharged in stable condition. Final histopathology report was high grade myxoid chondrosarcoma. The case was presented in tumour board and the patient was planned for adjuvant radiotherapy. She has been on regular follow up for the past 2 years and shows no signs of recurrence. Conclusion: Extraskeletal myxoid chondrosarcoma of oral cavity is a rare entity and very few cases are reported. It is a malignant neoplasm which is diagnosed with the help of immunohistochemistry. Surgery is the ideal modality of treatment accompanied by adjuvant radiotherapy in cases of high-grade tumours. [ABSTRACT FROM AUTHOR]

To investigate the sensitivity of predictions to chemical kinetics models, two different kinetics models, GRI-Mech 3.0 and an 11-species syngas model, are compared by performing 3D finite-rate kinetics-based direct numerical simulations (DNS) of a temporally evolving turbulent non-premixed syngas flame. Dynamic adaptive chemistry and correlated transport techniques are applied to enable computationally efficient simulation with the detailed GRI-Mech 3.0. Both chemical kinetics models, providing comparable qualitative trends, capture local extinction and re-ignition events. However, significant quantitative discrepancies (86–100 K difference in the temperature field) indicate high sensitivity to the chemical kinetics model. The 11-species model predicts a lower radicals-to-products conversion rate, causing statistically more local extinction and less re-ignition. This sensitivity to the chemical kinetics model is magnified relative to a 1D steady laminar simulation by the effects of unsteadiness and turbulence (up to 7 times for temperature, up to 12 times for CO, up to 13 times for H 2 , up to 7 times for O 2 , up to 5 times for CO 2 , and up to 13 times for H 2 O), with the deviations in species concentrations, temperature, and reaction rates forming a nonlinear positive feedback loop under reacting flow conditions. The differences between the results from the two models are primarily due to: (a) the larger number of species and related kinetic pathways in GRI-Mech 3.0; and (b) the differences in reaction rate coefficients for the same reactions in the two models. Both (a) and (b) are sensitive to unsteadiness and other turbulence effects, but (b) is dominant and is more sensitive to unsteadiness and other turbulence effects. At local extinction, the major differences between the results from the two chemical kinetics models are in the peak values and the volume occupied by the peak values, which is dominated by unsteady effects; at re-ignition, the differences are mainly observed in the spatial distribution of the reacting flow field, which is primarily dominated by the complex turbulence–chemistry interaction. [ABSTRACT FROM AUTHOR]

Extraosseous osteosarcoma is a rare malignant soft tissue neoplasm, and extraosseous osteosarcoma of the parotid gland is very rare. It has a very aggressive course, and there are no standardized treatment guidelines. We report the case of a 20 year old male patient who presented with history of right neck swelling since 6 years for which he had undergone right parotid surgery 5 years ago. The final histopathological report indicated that the mass was a pleomorphic adenoma. One year after the first surgery, the patient experienced recurrence of swelling over the operated site, and the size of the swelling has been increasing gradually since then. He was evaluated clinically, and a large mass was noted over the upper aspect of the right upper neck, extending to the occipital and parotid regions. An MRI scan was done which showed a 12 × 10 × 8 cm lesion centred in the right parotid gland, involving paraspinal muscles, C1–C2 vertebrae and extending into the parapharyngeal space. FNAC of the lesion showed features of pleomorphic adenoma. The patient underwent a complete excision of the tumour. The patient's post-operative period was uneventful. The final histopathological report of the patient was extraosseous osteosarcoma of the parotid gland. The patient was referred for adjuvant radiotherapy. He has been on regular follow-up for the past 6 months and has shown no sign of recurrence. EOS is an extremely rare tumour of the head and neck region which often requires extensive surgical resection with or without adjuvant radiotherapy. It has a high rate of local recurrence and a very low disease free survival. Such patients should be kept on a close follow-up. [ABSTRACT FROM AUTHOR]

Schwannomas are benign nerve tumours arising from the Schwann cells. Approximately 25-45% of schwannomas occurs in the head and neck region. Majority of schwannomas in the head and neck region arise from the vagus nerve. Trigeminal schwannomas account for about 0.2% of all intracranial tumours. Trigeminal schwannomas can originate from any section of the fifth cranial nerve, from the root to the distal extracranial branches, but majority develops from the Gasserian ganglion, usually growing in the middle cranium. Most common presenting symptom is facial pain. MRI is the imaging modality of choice and CT scan usually serves as a supplementary imaging especially for skull base tumours. 47 year old male patient presented to the outpatient department with complains of swelling over the left side of palate. Contrast enhanced CT scan demonstrated a large bilobed heterogeneously enhancing soft tissue lesion in the left infratemporal fossa with widened foramen ovale and extension of lesion into the Meckel's cave, larger contiguous component extending into ramus of mandible. MRI scan showed a large lobulated mass in the left masticator space with intracranial extension. Biopsy of the lesion was suggestive of schwannoma. The patient underwent left composite resection with dural repair and free flap reconstruction. Post operatively, on day 5 he developed features of meningitis for which he was treated conservatively and later discharged in stable condition. Trigeminal schwannomas are rare tumours with very low chance of malignant transformation which commonly presents with facial pain. MRI is the imaging modality of choice. Complete surgical excision is the treatment of choice. [ABSTRACT FROM AUTHOR]

Objectives – Transoral robotic surgery (TORS) is an already well established modality of treatment for early stage oropharyngeal cancer. This case report will throw light on the role of TORS as a treatment option for oropharyngeal cancer in a salvage setting. Methods – This is a case of a 69 year old patient who was a follow up case of carcinoma base of tongue, status - post concurrent chemoradiation who presented with residual disease at the primary site. Results – TORS was used as a successful treatment modality for base of tongue carcinoma in a salvage setting. The surgical procedure included removal of the entire hyoid bone in toto along with the tumour which is not reported in literature. The procedure also helped us in achieving an R0 resection. Conclusion – TORS should be considered as an important management modality for tongue base tumours in upfront as well as salvage setting. [ABSTRACT FROM AUTHOR]

Cervical lymph node metastasis is one of the most common clinical presentations of papillary thyroid carcinoma (PTC). Occult thyroid carcinoma is described as absence of primary tumour or with presence of microcarcinoma in thyroid with cervical lymph node metastasis. Frequency of occult thyroid cancer has decreased due to developments in imaging and improved accuracy of histological examinations. 38 year old male presented to us with complaints of swelling over the left side of neck for the past 2 months. Ultrasonography was suggestive of multiple suspicious enlarged nodes in left level II, III, IV and V and fine needle aspiration cytology showed features of metastatic PTC. He was planned for total thyroidectomy with central compartment clearance and bilateral functional neck dissection. Final histopathology staging was pT0N1b. Radioactive iodine (RAI) screening showed residual functioning thyroid and later therapeutic RAI was administered. He has been on regular follow up and disease free for 1 year post treatment. Occult thyroid carcinoma is a rare diagnosis with multiple treatment plans. Few hypothesis for this entity includes tumor regression, ectopic thyroid carcinoma or missed pathological findings. [ABSTRACT FROM AUTHOR]

Myofibrosarcoma is a distinct mesenchymal malignancy which commonly occurs in head and neck region. It has a high tendency for local recurrence and distant metastasis. 39-year-old male presented with epistaxis, nasal obstruction and left sided complete loss of vision. He underwent functional endoscopic sinus surgery and guided biopsy. MRI scan showed a lesion epicentred in the left maxillary sinus, superiorly extending into the orbit. He underwent Class 4b maxillectomy with neck dissection, tracheostomy and free flap reconstruction. Histopathological examination yielded final diagnosis as myofibrosarcoma of maxilla. The patient was planned for adjuvant radiotherapy and has been disease free for 3 years. [ABSTRACT FROM AUTHOR]

131-I radioactive iodine (RAI) scan is an important modality in the management of differentiated thyroid cancer to detect recurrent or residual disease. Thus it is important to have knowledge about the possibility of false positive findings in these scans to avoid wrongful diagnosis and unnecessary treatment. We here by present a patient who underwent total thyroidectomy with lymph node dissection and followed by radioactive iodine therapy for papillary thyroid cancer. He had 131-I iodine avid nodular lesion in the left parotid gland which was later proven to be oncocytoma on histopathology. False positive findings on radioactive iodine scans are a possibility which should be known to surgeons as well as nuclear medicine physicians for accurate diagnosis and appropriate management. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the oncological and functional outcomes following transoral robotic surgery (TORS) in human papilloma virus negative supraglottic cancers.Study Design: A prospective observational study at a tertiary cancer care center, New Delhi, India.Materials and Methods: From February, 2013 to December, 2015, 45 patients with supraglottic lesions underwent TORS using the da Vinci® surgical system.Results: Forty-five patients underwent TORS for supraglottic laryngectomy (SGL), with all patients undergoing bilateral neck dissection. The most common site was Ary-epiglottic fold. 47.9% were cT1 and 52.1% were cT2. Average robotic set-up time was 8.8 min and average robotic operative time was 42.9 min. A positive or close margin was seen in 12 patients (26.7%) on frozen, which were revised intraoperatively. On final histology, 3 (6.7%) patients had a margin of <5 mm. The average closest margin was 5.7 mm. Patients tolerated oral feeds within 2 weeks of procedure. All patients were HPV negative. Postoperatively, all patients had adequate swallowing and speech. Follow-up ranged from 24 to 58 months. Thirty-eight (84.4%) patients were alive and disease free.Conclusion: TORS is a safe, feasible, minimally invasive, and oncologically safe procedure in patients with early HPV supraglottic cancers. It has less morbidity and offers benefits in terms of early airway and feeding rehabilitation and avoids complications resulting from radiation therapy for these patients. [ABSTRACT FROM AUTHOR]

Papillary thyroid carcinoma (PTC) is the most common differentiated thyroid neoplasm. Common sites of regional and distant metastasis includes lymph nodes, lungs and bone. 51 year old female patient who was a known case of PTC with a history of multiple surgeries, radioactive iodine therapy (RAI) and oral chemotherapy presented with a painful right parotid mass. PET scan demonstrated FDG avid lesions in the right parotid gland, cervical lymph nodes and other distant sites. Cytology report showed features of metastatic PTC. Patient underwent extended total parotidectomy with facial nerve resection, skin and masseter muscle resection and extended radical neck dissection. Final histopathology (HPE) report showed metastatic papillary carcinoma thyroid. Patient is currently on oral chemotherapy and on regular follow up. PTC rarely metastasizes to parotid gland and such cases have to be treated with surgery alone or with a combination of surgery and RAI based on tumour burden. [ABSTRACT FROM AUTHOR]

Objective: This prospective study aimed to see long-term oncological outcome of Transoral Robotic Surgery as single modality treatment for cT1-T2 N0 HPV negative oropharyngeal malignancies.Method: From March 2013 to October 2015, 57 patients with early stage oropharyngeal carcinoma underwent Transoral robotic surgery (TORS) with neck dissection using daVinci® Surgical system. Patients were evaluated for disease free survival, overall survival, locoregional and distant metastasis.Results: 57 patients (48 males and 9 females) underwent TORS for early stage oropharyngeal carcinoma. All patients underwent ipsilateral neck dissection and 12 patients underwent bilateral neck dissection. 49 patients with final histopathology suggestive of stage I and II disease did not received any adjuvant treatment. Mean age at presentation was 59.4years (37-88years). Most common site of involvement was the base of tongue (BOT) in 31 (54.8%) patients. Twenty-four (42.1%) patients were cT1 and 33 (57.9%) were cT2 at presentation. During follow-up, 2 (4.2%) patients recurred locoreginally and 1 (2.1%) patient had distant metastasis. Two patients expired due to causes other than malignancy. Forty-three (89.6%) patients were disease free on an average follow-up of 29months with an overall survival of 93.8% at mean follow-up of 29months.Conclusion: Transoral Robotic Surgery as a single modality treatment is a good option for cure in HPV negative early resectable oropharyngeal malignancies which are relatively unresponsive to radiation. TORS can be used to de-intensify the treatment of early stage oropharyngeal carcinoma and thus avoid the early and late toxicities associated with Radiotherapy/Chemoradiotherapy. [ABSTRACT FROM AUTHOR]

Background: The aim of this observational prospective study was to determine the technical feasibility, safety and adequacy of surgical margins for transoral robotic surgery (TORS) in oropharyngeal cancers. Methods: From March 2013 to May 2014, 60 patients with oropharyngeal lesions underwent TORS with or without neck dissection using the 'DaVinci' robot. Patients were observed and data recorded on surgical time, blood loss, complications and functional outcome of patients. Results: All 60 patients underwent TORS, with neck dissection performed in 45 of the patients. A positive margin was seen in two patients (3.3 %). Intent to treatment was radical in 42 patients and salvage in 18 patients. None of the patients required tracheostomy, and one patient (1.66 %) died postoperatively. Postoperative complications in the form of primary haemorrhage required active intervention in three patients. Average estimated blood loss was 26.5 ± 31.1 ml. Postoperatively, all patients had adequate swallowing and speech function with nasal twang reported in three patients on long-term follow up. Patients started tolerating oral feeds within a week of procedure (mean 3.96 days), with the nasogastric tube removed on the ninth postoperative day (mean 9.19 days). No long-term gastrostomy tube dependency was reported. Conclusion: TORS is a safe, feasible, minimally invasive procedure in patients with oropharyngeal cancers. It has the least morbidity and offers benefits in terms of avoidance of tracheostomy tube, prolonged Ryle's tube and gastrostomy dependency. [ABSTRACT FROM AUTHOR]