Static anti-windup compensator design for locally Lipschitz systems under input and output delays.

This paper proposes a static anti-windup compensator (AWC) design methodology for the locally Lipschitz nonlinear systems, containing time-varying interval delays in input and output of the system in the presence of actuator saturation. Static AWC design is proposed for the systems by considering a delay-range-dependent methodology to consider less conservative delay bounds. The approach has been developed by utilizing an improved Lyapunov-Krasovskii functional, locally Lipschitz nonlinearity property, delay-interval, delay derivative upper bound, local sector condition, L2 gain reduction from exogenous input to exogenous output, improved Wirtinger inequality, additive time-varying delays, and convex optimization algorithms to obtain convex conditions for AWC gain calculations. In contrast to the existing results, the present work considers both input and output delays for the AWC design (along with their combined additive effect) and deals with a more generic locally Lipschitz class of nonlinear systems. The effectiveness of the proposed methodology is demonstrated via simulations for a nonlinear DC servo motor system, possessing multiple time-delays, dynamic nonlinearity and actuator constraints.

Volatility connectedness of GCC stock markets: how global oil price volatility drives volatility spillover in GCC stock markets?

The study investigated the volatility connectedness of GCC stock market return and S&P global oil index returns using Diebold and Yilmaz (2012) method. The current study has also analyzed the possible impact of oil price volatility on net volatility spillover in GCC stock market returns pre- and post-COVID-19 period. The current study results suggest that the GCC stock markets have volatility connectedness with S&P Global Oil Index returns' volatility and across GCC stock markets. The GCC stock markets have greater volatility in their stock markets than volatility spillover from other GCC countries. Further investigation also suggests that global oil price volatility has a divergent causal impact on net spillover in GCC stock markets. Such results would enhance the understanding of GCC stock market connection, spillover, and economic channels through which GCC markets are connected.

Ethical Dilemmas in the Management of Head and Neck Cancers in the Era of the COVID-19 Pandemic.

Coronavirus disease 2019 (COVID-19) has emerged as an unforeseen challenge for head and neck cancer care providers. A similar challenge is also faced by other oncological fields, but the severity of this challenge is highest in otolaryngology because of the need for additional precautionary measures and curbs on the possibility of aerosol forming interventions related to the upper aerodigestive tract. In this narrative review, provision of ethical and consistent care on moral and professional grounds to head and neck cancer patients during the pandemic are discussed for professionals who provide head and neck oncology care.

Laryngeal Embryonal Rhabdomyosarcoma: A rare adult neoplasm.

The embryonal subtype of rhabdomyosarcoma is the most frequent, commonly seen in children. However, it is uncommon to discover this subtype in adults, especially in the larynx. We presented a rare case of a 63 years old man who presented with worsening hoarseness, dysphagia for solids, and dyspnea and was later diagnosed with embryonal rhabdomyosarcoma of the larynx.

The Utility of Frozen Sections in the Evaluation of Clear Margins in Oral Squamous Cell Carcinomas: A Cross-Sectional Study From a Tertiary Care Center.

Background and objective Head and neck cancers are prevalent in Pakistan. Oral squamous cell carcinomas are primarily treated via surgical removal, and complete surgical resection is the paramount prognostic factor. A resection margin of 5 mm on the final histopathology report has been accepted as adequate in the existing literature. Negative margins on the frozen section do not guarantee adequate disease-free resections on the final histopathology report. In this study, we aimed to ascertain how accurately tumor-free margins can be detected on frozen sections, which are reported intraoperatively compared to permanent sections of the same tissues reported after proper staining in oral squamous cell carcinoma patients. Methods A cross-sectional study was conducted at a tertiary care hospital in Karachi, Pakistan; 94 patients presenting between January and October 2016 were included in this study and a total of 432 tumor margins were assessed. Results Among the total 94 patients included in the study, 79% were male and 21% were female. Buccal mucosa was the most commonly involved subsite (57%), followed by the tongue (25%). The most common T stage was T4 (33%), followed by T2 and T3 at 28% and 21% respectively, while the most common N stage was N0 (55%) followed by N1 at 16% and N2 at 22%. The sensitivity of the frozen section in comparison to the permanent section was found to be 50%, while specificity was calculated to be 99.8%. The positive predictive value was 75% and the negative predictive value was 99.3%. Conclusion The frozen section is a highly useful tool for the evaluation of tumor margins. However, while it has high diagnostic accuracy rates, it can produce altered results and therefore requires high clinical correlation.

Locally Advanced Oral Tongue Cancer: Is Organ Preservation a Safe Option in Resource-Limited High-Volume Setting?

BACKGROUND: Oral tongue is found to be the most common intraoral subsite with worse prognosis despite the use of multimodality treatments. Extensive resections have resulted in loss of form and function of tongue in advanced tumors. The objective of the study was to analyze the role of induction chemotherapy (IC) in intermediate to advanced staged oral tongue cancer for organ preservation and survival outcome in a developing country. MATERIALS AND METHODS: The records of oral tongue cancer patients treated from 2007 to 2016 were retrospectively analyzed. RESULTS: Eighty-one oral tongue cancer patients with advanced stage were treated using induction arm in 10 years. The median follow-up was 24 months with 3- and 5-year survival of 77% and 58%, respectively. IC has an overall response in 87% of the patients at primary site. The chemotherapy has completely resolved the nodal disease in 17% of the patients, but 23% of the patients had failed to respond. Only 21% of the patients received reconstruction using local or regional flaps. CONCLUSION: IC has shown encouraging results in advanced staged oral tongue cancers with function preservation and improved survival outcome in less privileged high-volume centers.

COVID-19: Implications, Reactions and Future Directions.

Humanity has faced several foes over the centuries, a formidable one amongst them is the current pandemic of COVID-19. The symptoms of COVID-19 are more or less related to the nose and throat. Therefore, patients more often present to Ear Nose Throat (ENT) clinics with symptoms including cough, sore throat, fever and shortness of breath. In the management of head and neck pathologies, as the airway is a direct source of infection, the impact of COVID-19 holds special significance. This review has attempted to explain the various aspects of the disease itself, its diagnosis, the use of personal protective equipment (PPE) to provide an overview of the evolving recommendations in head and neck patients, the future outlook and the limitations faced in developing countries specifically for ENT patients.

Incidence of thyroid gland invasion in advanced laryngeal cancers and its impact on disease-specific survival; a retrospective review at a tertiary care center.

Background: Incidence of thyroid gland invasion in advanced laryngeal cancers is low. Ipsilateral or total thyroidectomy along with total laryngectomy has been controversial and there has been no consensus over the management of thyroid gland in advanced laryngeal cancers.Objective: To determine the frequency of thyroid gland invasion in locally advanced laryngeal squamous cell carcinoma and the risk factors associated with it.Material and methods: A retrospective review of patients with laryngeal squamous cell carcinoma operated at our center between January 2011 and December 2018 was carried out. Patients undergoing upfront or salvage laryngectomy with or without neck dissection along with hemi or total thyroidectomy were included. Histopathology reports were reviewed to record the involvement of thyroid gland.Results: Invasion of thyroid gland by squamous cell carcinoma larynx was seen in 10 (10.9%) patients out of 92. All of the cases showed direct extension of the tumor. Trans-glottic, subglottic, and tumors with extra laryngeal spread were found to be significantly associated with thyroid gland invasion. Patients with thyroid gland invasion showed higher rate recurrence.Conclusion and significance: Incidence of thyroid gland invasion in squamous cell carcinoma larynx is low, allowing us not to address thyroid routinely in patients undergoing total laryngectomy for laryngeal carcinoma.

Use of endoscope in teaching of otolaryngology residents about site and size of tympanic membrane perforation and its impact on degree of hearing loss in adult patients: A cross sectional study.

OBJECTIVE: To determine the association between site and size of perforation of the tympanic membrane and the level of conductive hearing. METHODS: The cross-sectional study was conducted from November 2015 to October 2016 at Aga Khan University Hospital Karachi and comprised patients with tympanic membrane perforation without any other middle-ear disease. Karl-Storz Rigid Endoscope attached to a camera was used to take pictures of the tympanic membrane. Site of the perforation was determined using a vertical line to divide the membrane into two anterior and posterior halves. Size of the perforation was calculated as a percentage of the total membrane using Image J software. Data analysis was done using Stata 12. RESULTS: Of the 55 patients, 29(53%) were males and 26(47%) were females. The overall mean age was 33+/-15 years. With every 5% increase in the size of perforation, the hearing loss increased by 1 decibel. A difference of 5.5 decibels was noted between anterior and posterior perforations of similar size. CONCLUSION: Hearing loss increased with increase in the size of perforation.

Effectiveness of plain X-ray in detection of fish and chicken bone foreign body in upper aerodigestive tract.

OBJECTIVE: To assess the use of plain film radiology in the detection of fish and chicken bones in the upper aerodigestive tract. METHODS: This retrospective chart review was conducted at the Aga Khan University Hospital, Karachi, and comprised medical charts of patients who had undergone oesophagoscopy for removal of fish and chicken bone from 1990 to 2015.SPSS 19 was used for data analysis. RESULTS: Of the 24 patients, foreign body was detected on X-ray in 7(29.2%) and through fibre optic laryngoscopy in 13(54.2%).All the patients underwent surgical intervention for removal of the foreign body. Also, 19(79.2%) patients underwent direct laryngoscopy and 5(16.7%) required oesophagoscopy. The sensitivity with X-ray was 15% and specificity was zero. The sensitivity of fibre optic laryngoscopy in comparison to intra-operative findings was 65% and the specificity was 100%. CONCLUSIONS: X-ray was not found to be an ideal modality to diagnose fish or chicken bone impaction in the upper aerodigestive tract.