SPINDLE CELL CARCINOMA OF LARYNX- A DISTINCT CLINICOPATHOLOGICAL AND HISTOLOGICAL ENTITY

Spindle cell carcinoma (SpCC) is a variant of squamous cell carcinoma with biphasic components and more aggressive behaviour. Its rarity and histopathological pattern pose a diagnostic challenge. Early diagnosis and treatment result in a decrease in local and distant metastasis. Case 1 is a 71-year-old female presented with hoarseness of voice and dyspnoea for 2 years without any risk factors. Fibre-optic laryngoscopy (FOL) revealed smooth polyp hanging from anterior two-third of the left vocal cord. Microlaryngoscopic excision revealed SpCC followed by post-operative radiotherapy and is currentlyalive. Case 2 is a 72-year-old male presented with worsening stridor for 2 years post-excision of laryngeal nodule and history of smoking and hookah use for >20 years. He developed dysphonia after a few months with fixed hard level 3 nodes at the right side. FOL showed a polypoid mass extending from the left vocal cord into the supraglottis. Fine-needle aspiration cytology of the neck swelling confirmed the diagnosis of SpCC. Computerised tomography (CT) chest/abdomen showed distant metastasis. Palliative radiotherapy was given, but the patient died after 3 months due to locoregional failure. Case 3 is a 35-year-old male presented with a history of hoarseness for 3 years with no risk factors. FOL showed a 1.2-cm polypoid growth on the right vocal cord. Total laryngectomy was performed and histopathology showed SpCC. Radiotherapy was given and the patient is alive without disease with regular follow-ups. Smoking and alcohol are thought to be the contributing factors causing this disease. Biphasic nature of the tumour requires pathological sampling for diagnostic confirmation. Surgery combined with radiotherapy has a better survival outcome. SpCC is a rare tumour with a tendency for locoregionalrecurrence. Surgery should remain the mainstay of treatment followed by post-operative radiotherapy for a better control.Key words: Larynx, radiotherapy, spindle cell carcinom

Flexible joint robotic manipulator: Modeling and design of robust control law

This paper presents modeling and sophisticated control of a single Degree Of Freedom (DOF) flexible robotic arm. The derived model is based on Euler-Lagrange approach while the first and second order (super twisting) Sliding Mode Control (SMC) is proposed as a non-linear control strategy. The control laws are subjected to various test inputs including step and sinusoids to demonstrate their tracking efficiency by observing transient and steady state behaviours. Both orders of SMC are then compared to characterize the control performance in terms of robustness, handling external disturbances and chattering. Results dictate that the super twisting SMC is more accurate and robust against the external noise and chattering phenomena compared to the first order SMC

A robust variable-structure LQI controller for under-Actuated systems via flexible online adaptation of performance-index weights

This article presents flexible online adaptation strategies for the performance-index weights to constitute a variable structure Linear-Quadratic-Integral (LQI) controller for an underactuated rotary pendulum system. The proposed control procedure undertakes to improve the controller s adaptability, allowing it to flexibly manipulate the control stiffness which aids in efficiently rejecting the bounded exogenous disturbances while preserving the system s closed-loop stability and economizing the overall control energy expenditure. The proposed scheme is realized by augmenting the ubiquitous LQI controller with an innovative online weight adaptation law that adaptively modulates the state-weighting factors of the internal performance index. The weight adaptation law is formulated as a pre-calibrated function of dissipative terms, anti-dissipative terms, and model-reference tracking terms to achieve the desired flexibility in the controller design. The adjusted state weighting factors are used by the Riccati equation to yield the time-varying state-compensator gains

Non-linear control law for articulated serial manipulators: Simulation augmented with hardware implementation

The performance of a robotic arm includes accuracy, repeatability and reliability to accomplish a task. These parameters, in turn, are function of associated control law. Multi-Degree Of Freedom (DOF) robotic arms, because of their inherent highly non-linear dynamics, demand sophisticated control laws. Trivial control strategies fail to cope with disturbances and uncertainties that are common in today's plants. This paper presents the design, simulation and physical implementation of a non-linear control technique Variable Structure Control (VSC) for a 6 DOF arm. Based on the derived dynamic model of the arm and designed control law, simulations have been conducted in MATLAB/Simulink. The controller parameters have been tuned for optimal response. Various desired trajectories characterize the tracking performance of the control law. The simulation results have been then validated by implementing the law on a customdeveloped novel AUTonomous Articulated Robotic Educational Platform (AUTAREP). Coupling effects between various joints of the robot have also been investigated. Results of this research find potential in industrial control of robotic manipulators to perform complex tasks

Recent Advances in Minimally Invasive General Surgery A Retrospective Study

OBJECTIVESTo evaluate the outcomes of minimally invasive general surgery (MIGS) and determine the indications for MIGS and its success rate. METHODS This retrospective study was conducted at the surgery unit of Hayatabad Medical Complex (HMC) Hospital, Peshawar, from January 2021 to December 2022. All the 200 patients who underwent MIGS were included in the study. Data regarding demographic characteristics, clinical presentation, type of MIGS, and intraoperative and postoperative complications were collected from the medical records and analyzed. The outcome of the study was assessed based on the success rate of the MIGS procedure and the occurrence of any postoperative complications. RESULTS The mean age of the patients was 43.3 years (range 10–75 years). The most common indication for MIGS was cholecystectomy (33.5%). Other indications included appendectomy (17.5%), hernia repair (12%), small bowel resection (10%), and gastrectomy (7%). The overall success rate of MIGS was 97.5%. The most common postoperative complication was wound infection (6.5%). There were no deaths due to MIGS. CONCLUSION The study findings suggest that MIGS is a safe and effective procedure for managing various surgical diseases and can be performed with minimal morbidity and mortality. Further randomized controlled trials are needed to confirm the safety and efficacy of MIGS in different settings

Avoiding contingent incidents by quadrotors due to one or two propellers failure

With the increasing impact of drones in our daily lives, safety issues have become a primary concern. In this study, a novel supervisor-based active fault-tolerant (FT) control system is presented for a rotary-wing quadrotor to maintain its pose in 3D space upon losing one or two propellers. Our approach allows the quadrotor to make controlled movements about a primary axis attached to the body-fixed frame. A multi-loop cascaded control architecture is designed to ensure robustness, stability, reference tracking, and safe landing. The altitude control is performed using a proportional-integral-derivative (PID) controller, whereas linear-quadratic-integral (LQI) and model-predictive-control (MPC) have been investigated for reduced attitude control and their performance is compared based on absolute and mean-squared error. The simulation results affirm that the quadrotor remains in a stable region, successfully performs the reference tracking, and ensures a safe landing while counteracting the effects of propeller(s) failures

A featureless approach for object detection and tracking in dynamic environments

One of the challenging problems in mobile robotics is mapping a dynamic environment for navigating robots. In order to disambiguate multiple moving obstacles, state-of-art techniques often solve some form of dynamic SLAM (Simultaneous Localization and Mapping) problem. Unfortunately, their higher computational complexity press the need for simpler and more efficient approaches suitable for real-time embedded systems. In this paper, we present a ROS-based efficient algorithm for constructing dynamic maps, which exploits the spatial-temporal locality for detecting and tracking moving objects without relying on prior knowledge of their geometrical features. A two-prong contribution of this work is as follows: first, an efficient scheme for decoding sensory data into an estimated time-varying object boundary that ultimately decides its orientation and trajectory based on the iteratively updated robot Field of View (FoV); second, lower time-complexity of updating the dynamic environment through manipulating spatial-temporal locality available in the object motion profile. Unlike existing approaches, the snapshots of the environment remain constant in the number of moving objects. We validate the efficacy of our algorithm on both V-Rep simulations and real-life experiments with a wide array of dynamic environments. We show that the algorithm accurately detects and tracks objects with a high probability as long as sensor noise is low and the speed of moving objects remains within acceptable limits

ORAL METHOTREXATE AS SECOND LINE CHEMOTHERAPY IN PLATINUM-REFRACTORY OR RELAPSED SQUAMOUS CELL CARCINOMA OF THE HEAD AND NECK

Purpose: Platinum-refractory or relapsed squamous cell carcinoma of the head and neck (SCCHN) is considered to have poor prognosis. Although cetuximab is currently recommended as category 1 in this group of patients, the use of it is hampered in low- and middle-income countries (LMICs) like Pakistan due to nancial constraints. Further, majority of the population of these countries is unable to tolerate toxicity related to other intravenous chemotherapeutic agents due to lower socioeconomic background with poor nutrition status. The aim of this study is to evaluate the response rate and toxicity of oral methotrexate (MTX) in platinum-refractory or relapsed SCCHN. Methods: Between June 2008 and December 2012, 71 patients received palliative oral MTX either due to recurrent or persistent disease. With a median age of 51 years (range 22–75), there were 68% of males and 32% of females. Site distribution was as following; oral cavity 58%, nasopharynx 25%, hypopharynx 7%, paranasal sinuses 6%, larynx 3%, Oropharynx 1%. Patterns of recurrence; local 32%, regional 07%, loco regional 10%, distant 15% and persistent disease in 36% of the patients. All the patients received oral MTX 10 mg once a day, 4 days a week. To contain the possible side effects associated with MTX, folinic acid 15 mg per oral every 6 hourly on day 5 was prescribed. Response assessment was done on two monthly basis. Response, toxicity, mean response time and mean time to progression were determined. Results: Response to MTX was as following; complete response 3%, partial response 4%, stable disease 11% and progressive disease in 82% of the patients respectively. Toxicity related to oral MTX includes neutropenia Grade III in 1% while mucositis Grade III in 10% of the patients, respectively. None of the patient had Grade IV mucositis or haematological toxicity. Treatment was stopped in 13% of the patients due to poor compliance. Mean response time was 4 months (range 1 – 20) and mean time to progression was 5 months (range 1–23). Conclusion: Oral MTX is a simple, cost-effective and well-tolerated regimen to be used on outpatient basis for palliation in platinum refractory or relapsed SCCHN in LMICs and debilitated patients. This treatment merits further evaluation in large-scale clinical trials. Key words: Oral methotrexate, platinum refractory, relapsed squamous cell carcinoma of head and neck