Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
Skip to main content

    Muhammad Jawad

    Gradient descent is the workhorse of deep neural networks. Gradient descent has the disadvantage of slow convergence. The famous way to overcome slow convergence is to use momentum. Momentum effectively increases the learning factor of... more
    Gradient descent is the workhorse of deep neural networks. Gradient descent has the disadvantage of slow convergence. The famous way to overcome slow convergence is to use momentum. Momentum effectively increases the learning factor of gradient descent. Recently, many approaches have been proposed to control the momentum for better optimization towards global minima, such as Adam, diffGrad, and AdaBelief. Adam decreases the momentum by dividing it with square root of moving averages of squared past gradients or second moment. The sudden decrease in the second moment often results in the overshoot of the gradient from the minima and then settle at the closest minima. DiffGrad decreases this problem by using a friction constant based on the difference of current gradient and immediate past gradient in Adam. The friction constant further decreases the momentum and results in slow convergence. AdaBelief adapts the step size according to the belief in the current gradient direction. Anot...
    In modern power systems, since most loads are inductive by nature, there is an ongoing power quality issue and researchers’ interest in improving the power factor is widespread, as inductive loads have a low power factor that depletes the... more
    In modern power systems, since most loads are inductive by nature, there is an ongoing power quality issue and researchers’ interest in improving the power factor is widespread, as inductive loads have a low power factor that depletes the system’s capacity and has an adverse effect on the voltage level. The measurement and acute analysis of voltage- and current-level waveforms is essential to tackle power quality issues. This article presents a detailed case study and analysis of real-time data measured from a frequency converter, which is used to operate the motor of a ventilation system. The output of the frequency converter is a highly distorted current wave. A hybrid Fourier transform (FT)- and wavelet transform-based solution has been proposed here to diagnose and identify the causes of motor failure in the ventilation system. The traditional FT did not give a detailed analysis of this type of signal, which is highly contaminated by noise. Therefore, first, the signal is prepro...
    Deployment of efficient and cost-effective parking lots is a known bottleneck for the electric vehicles (EVs) sector. A comprehensive solution incorporating the requirements of all key stakeholders is required. Taking up the challenge, we... more
    Deployment of efficient and cost-effective parking lots is a known bottleneck for the electric vehicles (EVs) sector. A comprehensive solution incorporating the requirements of all key stakeholders is required. Taking up the challenge, we propose a real-time EV smart parking lot model to attain the following objectives: (a) maximize the smart parking lot revenue by accommodating maximum number of EVs and (b) minimize the cost of power consumption by participating in a demand response (DR) program offered by the utility since it is a tool to answer and handle the electric power usage requirements for charging the EV in the smart parking lot. With a view to achieving these objectives, a linear programming-based binary/cyclic (0/1) optimization technique is developed for the EV charge scheduling process. It is difficult to solve the problems of binary optimization in real-time given that the complexity of the problem increases with the increase in number of EV. We deploy a simplified c...
    The benefits of oversewing the staple lines during laparoscopic sleeve gastrectomy have been controversial. No study examined the benefit of oversewing the staple lines in robotic sleeve gastrectomy (RSG). This retrospective study aims to... more
    The benefits of oversewing the staple lines during laparoscopic sleeve gastrectomy have been controversial. No study examined the benefit of oversewing the staple lines in robotic sleeve gastrectomy (RSG). This retrospective study aims to examine the difference in immediate postoperative complications, readmissions, reoperations, and emergency room visits between RSG patients with and without oversewn staple lines at a single, large-volume, bariatric center. A retrospective chart review was conducted on 623 patients who underwent RSG between November 1, 2017, and November 1, 2019. Of these, 316 had their staple line oversewn between November 1, 2017, and November 12, 2018, and 307 did not have their staple line oversewn between November 13, 2018, and November 1, 2019. A total of 623 patients underwent RSG, of which 50.7% (n = 316) had their staple line oversewn. The mean length of hospital stay was similar between the two groups. However, the mean operative time was significantly lo...
    The impact of nonlinear thermal radiations rotating with the augmentation of heat transfer flow of time-dependent single-walled carbon nanotubes is investigated. Nanofluid flow is induced by a shrinking sheet within the rotating system.... more
    The impact of nonlinear thermal radiations rotating with the augmentation of heat transfer flow of time-dependent single-walled carbon nanotubes is investigated. Nanofluid flow is induced by a shrinking sheet within the rotating system. The impact of viscous dissipation is taken into account. Nanofluid flow is assumed to be electrically conducting. Similarity transformations are applied to transform PDEs (partial differential equations) into ODEs (ordinary differential equations). Transformed equations are solved by the homotopy analysis method (HAM). The radiative source term is involved in the energy equation. For entropy generation, the second law of thermodynamics is applied. The Bejan number represents the current investigation of non-dimensional entropy generation due to heat transfer and fluid friction. The results obtained indicate that the thickness of the boundary layer decreases for greater values of the rotation parameter. Moreover, the unsteadiness parameter decreases t...
    Single anastomosis duodeno-ileal switch (SADI-S) involves a single, loop duodeno-ileal anastomosis with omission of the traditional Roux-en-Y distal ileo-ileal anastomosis. Not much has been published on the complications of SADI-S. The... more
    Single anastomosis duodeno-ileal switch (SADI-S) involves a single, loop duodeno-ileal anastomosis with omission of the traditional Roux-en-Y distal ileo-ileal anastomosis. Not much has been published on the complications of SADI-S. The patient is a 40 year-old male who underwent robot-assisted SADI-S three years prior. At the time of surgery, his body mass index (BMI) was 69 kg/m. His BMI was 31 kg/m at the time of presentation. Computed tomography of the abdomen and pelvis showed a liver with a nodular appearance and moderate ascites throughout the abdomen and above the liver. Liver function showed AST 73 U/L, ALT 63 U/L, alkaline phosphatase 128 U/L, bilirubin 1.0 mg/dL, and albumin 2.8 g/dL. He underwent diagnostic and therapeutic paracentesis with removal of 6L of fluid that was negative for infection or malignant cells. Esophagogastroduodenoscopy showed grade I esophageal varices and diffuse mild gastritis. Mild hepatic dysfunction is common after biliopancreatic diversion and...
    The surface coating is one of the novel approaches to enhance the performance and durability of the mechanical components by decreasing the wear and friction among two interacting bodies. In this study, tribological and mechanical... more
    The surface coating is one of the novel approaches to enhance the performance and durability of the mechanical components by decreasing the wear and friction among two interacting bodies. In this study, tribological and mechanical properties of titanium nitride (TiN) coatings were investigated on the AISI 52100 bearing steel deposited by low-temperature physical vapor deposition system. Surface morphology and elemental composition of the TiN coating were analyzed by scanning electron microscope and energy-dispersive X-ray spectrum, respectively. Substrate surface roughness and coating thickness of TiN were varied for correlative analysis among adhesion, mechanical, and tribological properties. Scratch and tribo tests were performed for evaluating the adhesion and tribological properties, respectively. Samples having the substrate surface roughness (0.2 ± 0.05 µm) and the coating thickness of more than 2.83 µm presented relatively better adhesion, wear resistance, and lower coefficie...
    ackground: Determination of wound age is pivotal in forensic medical sciences, criminal and civil cases for the construction of crime scene and answering the questions like, time of infliction, manner of wound infliction, how long the... more
    ackground: Determination of wound age is pivotal in forensic medical sciences, criminal and civil cases for the construction of crime scene and answering the questions like, time of infliction, manner of wound infliction, how long the person survives after infliction of wound and characterizing antemortem or postmortem wounds. The findings differ considerably among individuals due to the biological variations. Previous developed method in the injury-age determination is clinical, microscopic, enzymatic reaction at the wound margins, histological, and immunohistochemistry with the pitfalls associated with it.
    In this paper we propose a novel approach for defining Local Binary Patterns (LBP) to directly encode graph structure. LBP is a simple and widely used technique for texture analysis in static 2D images, and there is no work in the... more
    In this paper we propose a novel approach for defining Local Binary Patterns (LBP) to directly encode graph structure. LBP is a simple and widely used technique for texture analysis in static 2D images, and there is no work in the literature describing its generalisation to graphs. The proposed method (GraphLBP) is efficient and yet effective as a noise-tolerant graph-based representation. We compute the new feature representation for graphs by combining LBP with Galois Fields, using irreducible polynomials. The proposed method is scalable as it preserves the local and global properties of the graph. Experimental results show that GraphLBP can both increase the recognition accuracy and is both simpler and more computationally efficient when compared with state of the art techniques.
    The study investigates relevant significance of various economic determinants for inflows of worker’s remittances to Pakistan. Following precedence from the policy index developed by Burnside and Dollar (2000), we develop a policy index... more
    The study investigates relevant significance of various economic determinants for inflows of worker’s remittances to Pakistan. Following precedence from the policy index developed by Burnside and Dollar (2000), we develop a policy index for Pakistan and use it as a proxy for estimating the relationship of this policy index with the remittances in Pakistan. The study has also taken other conventional macroeconomic determinants into account such as GDP, exchange rate, labor force participation and interest rate spread for having efficient and precise coefficient estimates of our estimated model. The study finds that during the period (1972-2011) policy environment is one of the significant determinants of worker’s remittances in Pakistan. Further, the application of several post estimation tests ascertains that our empirical model is robust.
    Minimizing the costs of cloud services is important for cloud service providers to grow their business. In cost calculation of cloud services, power consumption cost is a major factor. The variability present in renewable power... more
    Minimizing the costs of cloud services is important for cloud service providers to grow their business. In cost calculation of cloud services, power consumption cost is a major factor. The variability present in renewable power generation, electricity price, and power demand variates the power utilization expenditures. Due to high computational requests, datacenters consume enormous energy every day, thereby necessitating the need for energy efficient designs. Therefore, an energy consumption cost reduction mechanism is required to optimize the data center’s power consumption cost locally and to have the option to redistribute the workload on geo-distributed data centers in peak hours for further reduction in power consumption cost. In this paper, the authors investigate the energy consumption cost optimization problem in cloud datacenters and propose a blockchain-based decentralized workload distribution and management model. Moreover, we minimize request scheduler time for transfe...
    In this paper, the steady electrically conducting hybrid nanofluid (CuO-Cu/blood) laminar-mixed convection incompressible flow at the stagnation-point with viscous and gyrotactic microorganisms is considered. Additionally, hybrid... more
    In this paper, the steady electrically conducting hybrid nanofluid (CuO-Cu/blood) laminar-mixed convection incompressible flow at the stagnation-point with viscous and gyrotactic microorganisms is considered. Additionally, hybrid nanofluid flow over a horizontal porous stretching sheet along with an induced magnetic field and external magnetic field effects that can be used in biomedical fields, such as in drug delivery and the flow dynamics of the microcirculatory system. This investigation can also deliver a perfect view about the mass and heat transfer behavior of blood flow in a circulatory system and various hyperthermia treatments such as the treatment of cancer. The simple partial differential equations (PDEs) are converted into a series of dimensional ordinary differential equations (ODEs), which are determined using appropriate similarities variables (HAM). The influence of the suction or injection parameter, mixed convection, Prandtl number, buoyancy ratio parameter, perme...
    After globalization, an upsurge in Merger & Acquisition (M&A) activities has been observed all over the globe especially in last decade, as same contributed towards the economic wellbeing of any country. Companies adopted different... more
    After globalization, an upsurge in Merger & Acquisition (M&A) activities has been observed all over the globe especially in last decade, as same contributed towards the economic wellbeing of any country. Companies adopted different Integration Strategies (Vertical, Horizontal & Conglomerate) to undergo the merger deals and accordingly their post merger financial performance analysis was documented for future reference. On the contrary, comparatively inadequate evidence is accessible to appreciate the outcome of this activity in Pakistan, which cannot be taken as reference for future M&A deals. Therefore, the present research investigate in a decent way the impact of various M&A Integration Strategies on the financial performance of the merged firms in Pakistan, with an aim to identify the best suited M&A Integration Strategy in own environment. Available data from pre and post merger financial Statements of 36 merger events categorized broadly into three Integration Strategies (year...
    This work investigates numerically the solution of Darcy–Forchheimer flow for hybrid nanofluid by employing the slip conditions. Basically, the fluid flow is produced by a swirling disk and is exposed to thermal stratification along with... more
    This work investigates numerically the solution of Darcy–Forchheimer flow for hybrid nanofluid by employing the slip conditions. Basically, the fluid flow is produced by a swirling disk and is exposed to thermal stratification along with non-linear thermal radiation for controlling the heat transfer of the flow system. In this investigation, the nanoparticles of titanium dioxide and aluminum oxide have been suspended in water as base fluid. Moreover, the Darcy–Forchheimer expression is used to characterize the porous spaces with variable porosity and permeability. The resulting expressions of motion, energy and mass transfer in dimensionless form have been solved by HAM (Homotopy analysis method). In addition, the influence of different emerging factors upon flow system has been disputed both theoretically in graphical form and numerically in the tabular form. During this effort, it has been recognized that velocities profiles augment with growing values of mixed convection paramete...
    Unsteady electrohydrodynamic hybrid nanofluid Al 2 O 3 ‐ Cu / H 2 O past a convective heat stretched/shrinked sheet is examined. A stagnation point fluid flow with velocity slip constrains and heat source or sink is deliberated. The... more
    Unsteady electrohydrodynamic hybrid nanofluid Al 2 O 3 ‐ Cu / H 2 O past a convective heat stretched/shrinked sheet is examined. A stagnation point fluid flow with velocity slip constrains and heat source or sink is deliberated. The combined set of PDEs is translated into ODEs by including approved similarity transformations. HAM is applied for the solution to the obtained nonlinear system. The magnetic input factor, Prandtl number, electric field factor, Eckert number, heat source factor, and unstable factor are the governing parameters. The impact of these factors on the temperature and velocity profiles features of the problem is considered with explanation. Intensification in values of electric and magnetic fields parameters enhanced the heat transfer rate. The greater Prandtl number lessens the temperature. Amplification in temperature is perceived for Eckert parameter. The heat transferred rate of hybrid nanofluid in the entire domain increases as the heat source increases, wh...
    Y-chromosome short tandem repeat polymorphisms (Y-STRs) are important in many areas of human genetics. Y chromosomal STRs being normally utilized in the field of forensic exhibit low haplotype diversity in endogamous populations and fail... more
    Y-chromosome short tandem repeat polymorphisms (Y-STRs) are important in many areas of human genetics. Y chromosomal STRs being normally utilized in the field of forensic exhibit low haplotype diversity in endogamous populations and fail to discriminate among male relatives from same pedigree. Rapidly mutating Y-STRs (RM Y-STRs) have been paid much attention in last decade. These 13 RM Y STRs have high mutation rates (>10-2) and have considerably higher haplotype diversity and discrimination capacity than conventionally used Y-STRs showing remarkable power, when it comes to differentiation in paternal lineages in endogamous populations. Previously, we have analyzed 2–4 generation, 99 pedigrees covering 1568 pairs of men covering 1–6 meioses from all over Pakistan and 216 male relatives from 18 deep rooted endogamous Sindhi pedigrees covering 1-7 meioses. Here we are presenting 861 pairs of men from 63 endogamous pedigrees covering 1-6 meioses from Punjabi population of Punjab, Pa...
    The prevalent use of the Internet of Things (IoT) devices over the Sea, such as, on oil and gas platforms, cargo, and cruise ships, requires high-speed connectivity of these devices. Although satellite based backhaul links provide vast... more
    The prevalent use of the Internet of Things (IoT) devices over the Sea, such as, on oil and gas platforms, cargo, and cruise ships, requires high-speed connectivity of these devices. Although satellite based backhaul links provide vast coverage, but they are inherently constrained by low data rates and expensive bandwidth. If a signal propagated over the sea is trapped between the sea surface and the Evaporation Duct (ED) layer, it can propagate beyond the horizon, achieving long-range backhaul connectivity with minimal attenuation. This paper presents experimental measurements and simulations conducted in the Industrial, Scientific, and Medical (ISM) Band Wi-Fi frequencies, such as 5.8 GHz to provide hassle-free offshore wireless backhaul connectivity for IoT devices over the South China Sea in the Malaysian region. Real-time experimental measurements are recorded for 10 km to 80 km path lengths to determine average path loss values. The fade margin calculation for ED must accommod...
    In the current work, the unsteady thermal flow of Maxwell power-law nanofluid with Welan gum solution on a stretching surface has been considered. The flow is also exposed to Joule heating and magnetic effects. The Marangoni convection... more
    In the current work, the unsteady thermal flow of Maxwell power-law nanofluid with Welan gum solution on a stretching surface has been considered. The flow is also exposed to Joule heating and magnetic effects. The Marangoni convection equation is also proposed for current investigation in light of the constitutive equations for the Maxwell power law model. For non-dimensionalization, a group of similar variables has been employed to obtain a set of ordinary differential equations. This set of dimensionless equations is then solved with the help of the homotopy analysis method (HAM). It has been established in this work that, the effects of momentum relaxation time upon the thickness of the film is quite obvious in comparison to heat relaxation time. It is also noticed in this work that improvement in the Marangoni convection process leads to a decline in the thickness of the fluid’s film.
    The concept of hybrid high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) grid systems brings a massive advantage to reduce AC line loading, increased utilization of network infrastructure, and lower operational... more
    The concept of hybrid high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) grid systems brings a massive advantage to reduce AC line loading, increased utilization of network infrastructure, and lower operational costs. However, it comes with issues, such as integration challenges, control strategies, optimization control, and security. The combined objectives in hybrid HVAC–HVDC grids are to achieve the fast regulation of DC voltage and frequency, optimal power flow, and stable operation during normal and abnormal conditions. The rise in hybrid HVAC–HVDC grids and associated issues are reviewed in this study along with state-of-the-art literature and developments that focus on modeling robust droop control, load frequency control, and DC voltage regulation techniques. The definitions, characteristics, and classifications of key issues are introduced. The paper summaries the key insights of hybrid HVAC–HVDC grids, current developments, and future research d...
    Mass spectrometry imaging (MSI) is an imaging technique used in analytical chemistry to study the molecular distribution of various compounds at a micro-scale level. For each pixel, MSI stores a mass spectrum obtained by measuring signal... more
    Mass spectrometry imaging (MSI) is an imaging technique used in analytical chemistry to study the molecular distribution of various compounds at a micro-scale level. For each pixel, MSI stores a mass spectrum obtained by measuring signal intensities of thousands of mass-to-charge ratios (m/z-ratios), each linked to an individual molecular ion species. Traditional analysis tools focus on few individual m/z-ratios, which neglects most of the data. Recently, clustering methods of the spectral information have emerged, but faithful detection of all relevant image regions is not always possible. We propose an interactive visual analysis approach that considers all available information in coordinated views of image and spectral space visualizations, where the spectral space is treated as a multi-dimensional space. We use non-linear embeddings of the spectral information to interactively define clusters and respective image regions. Of particular interest is, then, which of the molecular ...
    This study investigates the current account deficit (CAD) of Turkey from the perspective of its capital account. We discuss how global liquidity conditions and monetary policies in Turkey have contributed to higher deficits through real... more
    This study investigates the current account deficit (CAD) of Turkey from the perspective of its capital account. We discuss how global liquidity conditions and monetary policies in Turkey have contributed to higher deficits through real exchange rate appreciations. We analyze the impact and consequences of exchange rate (ER) changes on the investments of non-financial firms. In the case of real ER depreciations, we find that the magnitude of the contractionary effect through balance sheets of firms with dollarized liabilities is significantly higher than the expansionary effect through trade competitiveness. We also analyze the " soft-landing " policies aimed at reducing the CAD in Turkey and estimate the rate of economic growth that must be foregone for a percentage reduction in CAD. Turkey has registered remarkable economic growth over the last decade, except for some setbacks in 2009 and 2014. However, persistent and large current account deficit (CAD) of the country casts shadow on the sustainability of this growth. Turkey's reliance on foreign short-term capital inflows to finance its CAD makes its economy vulnerable to external shocks and global financial conditions. Issues with external exposure have had troublesome patterns in the recent history of many emerging markets (EMs). A considerable amount of research has been conducted on the analysis of the current account from the perspectives of the trade balance (Kalyoncu 2005; Kayıkçı 2012; Özata 2014; Özlale and Pekkurnaz 2010). Mostly, such research places major emphasis on structural problems such as a low level of value added, energy import dependency and a lack of competitiveness of the country in question. However, very little has been done in the investigation of the capital account 1 , which is " the other side of the coin " with respect to the current account. Starting from the early 2000s, the world has been undergoing high global liquidity (GL hereafter) conditions. Shin (2013) distinguished two phases of GL. The first is the 2003–2008 phase, which had the global banking system at the center. Global banking had a dominant role in facilitating the transmission of looser financial conditions across borders through the acceleration of banking sector capital flows. The second phase started around 2010 and the main stage has been the bond market, especially the market for emerging market debt securities that are open to international investors. These liquidity conditions coincided with favorable economic conditions in emerging markets. Indeed, Turkey is one of these emerging countries, which has significantly improved its macroeconomic stability by implementing a new set of economic policies and intensive structural reforms starting from the 2000s (Yörükoğlu and Çufadar 2008). Moreover, Bernanke (2005) explained that the world " saving glut " can be one of the reasons of increased cross-border supply of capital. He stated that high levels of global savings in mature industrial economies as well as in developing economies with high foreign exchange reserve accumulations have been flowing into other countries which
    This research paper investigates two dimensional liquid film flow of Sisko nanofluid with variable heat transmission over an unsteady stretching sheet in the existence of uniform magnetic field. The basic governing time-dependent... more
    This research paper investigates two dimensional liquid film flow of Sisko nanofluid with variable heat transmission over an unsteady stretching sheet in the existence of uniform magnetic field. The basic governing time-dependent equations of the nanofluid flow phenomena with Sisko fluid are modeled and reduced to a system of differential equations with use of similarity transformation. The significant influence of Brownian motion and thermophoresis has been taken in the nanofluids model. An optimal approach is used to obtain the solution of the modeled problems. The convergence of the Homotopy Analysis Method (HAM) method has been shown numerically. The variation of the skin friction, Nusselt number and Sherwood number, their influence on liquid film flow with heat and mass transfer have been examined. The influence of the unsteadiness parameter [Formula: see text] over thin film is explored analytically for different values. Moreover for comprehension, the physical presentation of...
    In this research, the three-dimensional nanofluid thin-film flow of Casson fluid over an inclined steady rotating plane is examined. A thermal radiated nanofluid thin film flow is considered with suction/injection effects. With the help... more
    In this research, the three-dimensional nanofluid thin-film flow of Casson fluid over an inclined steady rotating plane is examined. A thermal radiated nanofluid thin film flow is considered with suction/injection effects. With the help of similarity variables, the partial differential equations (PDEs) are converted into a system of ordinary differential equations (ODEs). The obtained ODEs are solved by the homotopy analysis method (HAM) with the association of MATHEMATICA software. The boundary-layer over an inclined steady rotating plane is plotted and explored in detail for the velocity, temperature, and concentration profiles. Also, the surface rate of heat transfer and shear stress are described in detail. The impact of numerous embedded parameters, such as the Schmidt number, Brownian motion parameter, thermophoretic parameter, and Casson parameter (Sc, Nb, Nt, γ), etc., were examined on the velocity, temperature, and concentration profiles, respectively. The essential terms o...
    With the increase in popularity of laparoscopic sleeve gastrectomy (LSG), the number of patients experiencing weight regain has increased as well. This study aims to demonstrate the outcomes of LSG conversions to Roux-en-Y gastric bypass... more
    With the increase in popularity of laparoscopic sleeve gastrectomy (LSG), the number of patients experiencing weight regain has increased as well. This study aims to demonstrate the outcomes of LSG conversions to Roux-en-Y gastric bypass (RYGB), double anastomosis duodenal switch (DS), and single anastomosis duodeno-ileal sleeve (SADI-S) due to weight regain. A retrospective chart review was performed on 21 patients who underwent a conversion of LSG due to weight regain between March 1, 2013, and April 30, 2017. A longitudinal analysis was performed for the body mass index (BMI) measures, using multilevel model for change. Of 21 patients, 6 underwent a conversion to RYGB, 9 underwent a conversion to SADI-S, and 6 underwent a conversion to double anastomosis DS. Mean percentage of total weight loss was 16.0% at 6 months, 20.1% at 12 months, 18.8% at 24 months, and 21.8% at 36 months after the procedure. The final model suggests that preoperative BMI is the most significant indicator ...
    Complications after bariatric procedures including leaks and strictures can be difficult to treat. Endoscopic treatment may be preferable due to its less invasiveness. The aim of this study is to describe usage of stents in treating... more
    Complications after bariatric procedures including leaks and strictures can be difficult to treat. Endoscopic treatment may be preferable due to its less invasiveness. The aim of this study is to describe usage of stents in treating complications after bariatric procedures, along with its indications, methods, and outcome. A total of 87 patients underwent endoscopic stenting after a bariatric procedure from January 1, 2013, and December 31, 2016, in four bariatric centers. Previous bariatric procedures included Roux-en-Y gastric bypass (RYGB) (n = 33), sleeve gastrectomy (n = 50), duodenal switch (DS, n = 2), and vertical banded gastroplasty (VBG, n = 2). Mean age at intervention was 42.6 ± 10.0 years old, and mean body mass index was 41.6 ± 4.0 kg/m at the time of bariatric procedure. Reasons for stenting included sleeve leakage (n = 48), gatrojejunostomy (GJ) leakage (n = 21), stricture (n = 8), staple-line disruption (n = 7), and obstruction at the site of ring (n = 2). Migration occurred in 19.5% (n = 17) of patients undergoing stent placement and required repositioning or replacement of stents. Stenosis occurred in 13.8% of patients, which required endoscopic dilatation after stent removal. Stents may be useful and effective in managing complications after different bariatric procedures, including RYGB and LSG.

    And 98 more