varun singh - Academia.edu (original) (raw)

Papers by varun singh

Online Journal of Health & Allied Sciences, 2020

Introduction: Metastases to the sinonasal region is rare and presents with features overlapping w... more Introduction: Metastases to the sinonasal region is rare and presents with features overlapping with various regional neoplastic/non-neoplastic lesions. This series aims to highlight the clinical presentations and diagnostic difficulties of sinonasal metastases. Material and Method: A review of pertinent demographic and laboratory data for patients diagnosed with metastases to the sinonasal region, over a period of 6 years (2012- 2017) was done. Results and Discussion: Seven cases (males- 6, females-1) of sinonasal metastases were identified. The age ranged from 41-72 years. The common clinical presentation was nasal obstruction, epistaxis, and pain. Grossly tumors were irregular masses (mean size – 4.1cm) with maxillary sinus as the most common site. The histologic types included Squamous cell carcinoma (3 cases), clear cell renal cell carcinoma (2 cases), and one case each of infiltrating ductal carcinoma, and eccrine spiradenocarcinoma. The site of the primary tumor was larynx (2...

Journal of Krishna Institute of Medical Sciences University, 2019

Epithelioid leiomyoma is a rare variant of leiomyoma. The tumour includes three distinct entities... more Epithelioid leiomyoma is a rare variant of leiomyoma. The tumour includes three distinct entities, leiomyoblastoma, clear cell leiomyoma and plexiform leiomyoma. It is histologically characterised by epithelioid cells, clear cells or plexiform pattern in varied proportions. We report a case of a 49-year-old female with complaints of palpable mass per abdomen and spotting per vagina. Radiology revealed a complex cystic mass with obscured right ovary. She underwent total abdominal hysterectomy with bilateral salpingooophorectomy. Pathological examination showed a posterior wall lesion with central 9 × 8 cm cyst with multiple septations and surrounding rim of solid areas. Microscopic examination showed a clear cell epithelioid leiomyoma. No mitosis/tumour cell necrosis was seen. The clinical course of epithelioid leiomyoma is still unclear owing to absence of large studies. Small size, clear cell histology, mitosis of < 2/10 High Power Field (HPF) and hyalinization are features of a...

Journal of Krishna Institute of Medical Sciences University, 2020

Delta-beta Thalassemia is a rare variant of thalassemia with elevated Hb F. Heterozygous and homo... more Delta-beta Thalassemia is a rare variant of thalassemia with elevated Hb F. Heterozygous and homozygous state of delta-beta thalassemia present with features similar to Hereditary Persistence of Fetal Haemoglobin (HPFH) and beta thalassemia intermedia. Here, we describe a case of 8-month-old female child with anaemia and splenomegaly. Haemoglobin electrophoresis showed 100% HbF and no HbA and HbA2. Patient was put on haematinics and advised a repeat haemoglobin electrophoresis after completion of 1 year of age, and family screening. Hb electrophoresis of the patient at the age of 2 years mirrored the earlier findings and her father, mother and brother showed increased Hb F with normal HbA2 levels. A final diagnosis of homozygous delta-beta thalassemia in the case with sibling and parents being heterozygous delta-beta thalassemia trait was rendered. Haemoglobin electrophoresis with red cell indices forms an important diagnostic clue in differentiating delta-beta thalassemia from othe...

A MULTIPLEXER is an essential electronic device which is basically used for all kind of electroni... more A MULTIPLEXER is an essential electronic device which is basically used for all kind of electronic switching. It is commonly called as data selector. The contemporary in VLSI is demanding the need of devices which dissipates low power. Adiabatic logic family is fulfilling our demands, which dissipates low power through them. In this paper, we have studied the various adiabatic logic styles: Adiabatic dynamic CMOS logic, two phase drive adiabatic dynamic logic, Glitch free and Cascadable adiabatic logic and two phase clocked adiabatic static CMOS logic. Further, we design a 2:1 multiplexer using Static CMOS and 2PADCL logic style. The 2:1 multiplexer was designed and simulated using HSPICE with 180nm technology parameters provided by predictive technology. The 2:1 multiplexer designed using 2padcl is analyzed on the basis of average power consumed by them for various values of load capacitance, input frequency and temperature. The results are then compared with static CMOS. It is obs...

Winging of scapula occurs most commonly due to injury to long thoracic nerve supplying serratus a... more Winging of scapula occurs most commonly due to injury to long thoracic nerve supplying serratus anterior muscle. Traumatic injury to serratus anterior muscle itself is very rare. We reported a case of traumatic winging of scapula due to tear of serratus anterior muscle in a 19-year-old male. Winging was present in neutral position and in extension of right shoulder joint but not on "push on wall" test. Patient was managed conservatively and achieved satisfactory result.

The most common cause of proximal radioulnar synostosis in adults is traumatic, usually after for... more The most common cause of proximal radioulnar synostosis in adults is traumatic, usually after forearm fractures. Disabling complications are mainly loss of rotatory movements of the forearm. Various surgical procedures have been described in the literature to end up in forearm synostosis as a complication. We here presented a rare case of proximal forearm synostosis following a common but improper surgical technique for an olecranon fracture complicated by implant infection. The synostosis was treated by resection and fascia lata interposition graft.

Background: Acute pancreatitis is one of the most common abdominal pathologies having variable ou... more Background: Acute pancreatitis is one of the most common abdominal pathologies having variable outcome ranging from self limiting abdominal pain to high mortality and morbidity due to organ failure, over the past five decades, various classification systems have emerged to classify pancreatitis according to its severity , and the associated complications have emerged to classify acute pancreatitis and its various complications, such as Apache Scoring , Ct Severity , Modified Ct Severity ,Ransen and Atlanta Classification. Objectives: We in our study will be classifying patients suffering from acute pancreatitis according to the revised Atlanta classification to divide them into interstitial edematous pancreatitis and necrotizing pancreatitis. The local complications will be classified according to CT imaging findings into acute necrotic collection, psuedocyst, acute necrotic collection and walled of necrosis. Organ failure will be assessed according to modified marshal scoring syste...

Materials, Methods and Procedures: A multicenter, retrospective multicenter study was conducted o... more Materials, Methods and Procedures: A multicenter, retrospective multicenter study was conducted on patients with AF who underwent cardiac CT prior to catheter ablation between 01/01/2010 and 12/31/2015. Patients were grouped by presence or absence of prior CVA/TIA. Patients with mitral stenosis, prior mechanical aortic valve replacement, ascending aortic arch atheroma, highrisk patent foramen ovale, history of atrial septal repair or device, preexisting LAA thrombus or intra-cardiac tumor, or prior open-heart surgery were excluded. Further exclusion was performed for patients with sub-optimal or unavailable cardiac CT imaging by investigators blinded to clinical data. Blinded investigators obtained RL by measuring the distance between the left superior pulmonary venous ostium and the internal ostium of the left atrial appendage. LAA FD was calculated using semi-automated volume rendering and processing software (ImageJ, Bethesda, MD) [1] and LAA FD are presented as means (95% confid...

A heat exchanger is usually characterized by two types of thermodynamic losses. First of these tw... more A heat exchanger is usually characterized by two types of thermodynamic losses. First of these two losses is associated with the heat transfer across a finite temperature difference. The second loss is due to pressure drop due to friction in a heat exchanger. The loss associated with heat transfer across a finite temperature difference can be mitigated by increasing the heat transfer area and reducing the local temperature difference through enhancements. However, increasing the heat transfer area can lead to greater overall frictional loss and higher pressure drop. This shows that the two losses are mutually conflicting, which points to the existence of an “optimum” heat exchanger design where these two losses are minimized. The two losses can be quantified by a single number which is the total entropy generated in the heat exchanger. Total entropy generation should be minimized to arrive at an optimum heat exchanger design. In this paper, the principle of entropy generation minimi...

─ In this work a Yee’s mesh based full vectorial transverse finite difference frequency (FDFD) mo... more ─ In this work a Yee’s mesh based full vectorial transverse finite difference frequency (FDFD) modesolver has been derived from discretized Maxwell’s equations in Matrix form for anisotropic waveguides with arbitrary permittivity and permeability tensors. This work incorporates arbitrary permittivity and permeability simultaneously into matrix equations of Yee’s mesh based modesolver, which previous works have not done. For benchmarking the Python implementation of these matrix equations, cross section of Yittrium Iron Garnate (YIG) channel waveguide has been taken as first one of the three test structures. Numerical result from this work has been compared with that from previous work on YIG channel waveguide and is found to be in good agreement. Further, for benchmarking the effective index values of waveguides having both permittivity and permeability anisotropic simultaneously, a finite element based commercial software (COMSOL) has been used, the values of effective indexes from...

Sturge Weber syndrome is a type of neurocutaneous disorder also known as meningofacial angiomatos... more Sturge Weber syndrome is a type of neurocutaneous disorder also known as meningofacial angiomatosis. It is generally seen in paediatric age group and more commonly effects the males which present with delayed milestones, seizure disorder, loss of vision and other neurological deficits. Clinical suspicion of Sturge weber syndrome should be made on the presence of port wine stain(facial nevus) in a young children. MRI (magnetic resonance imaging) plays a key role in detecting the various spectrum of cortical and vascular defects associated with the syndrome. Clinicians can come to a final diagnosis of Sturge weber syndrome, when the clinical history is supplemented with MRI findings. We in our case report will be discussing the various spectrum of MR findings in this rare neurocutaneous syndrome.

In fin-and-tube heat exchangers operating at high temperatures such as Carbon Dioxide gas coolers... more In fin-and-tube heat exchangers operating at high temperatures such as Carbon Dioxide gas coolers, the heat transfer between neighboring tubes due to fin conduction affects the heat exchanger performance. In this research, a segment-by-segment heat exchanger model has been developed that can account for tube-to-tube conduction in two dimensions. The new model has been validated against experimental data for a gas cooler at 36 test conditions with total heat load varying between 6kW and 12kW. The refrigerant temperatures were measured at 27 locations on the different U-bends in the coil. The predicted heat load agreed within 3% and the refrigerant temperatures, agreed within 3.3K of measured values. The model is capable of simulating a heat exchanger that has both continuous and discontinuous i.e. cut fins. This paper investigates the effect of fin cuts on the performance of a Carbon Dioxide gas cooler through an exhaustive search method. In this approach, tubes are progressively sep...

Photosynthesis Research

Graphene quantum dots (GQDs) and nanoribbons (GNRs) are classes of nanographene molecules that ex... more Graphene quantum dots (GQDs) and nanoribbons (GNRs) are classes of nanographene molecules that exhibit highly tunable photophysical properties. There have been great strides in recent years to advance our understanding of nanographene photophysics and develop their use in light-harvesting systems, such as artificial photosynthesis. Here, we review the latest studies of GQDs and GNRs which have shed new light onto their photophysical underpinnings through computational and advanced spectroscopic techniques. We discuss how the size, symmetry, and shape of nanographenes influence their molecular orbital structures and, consequentially, their spectroscopic signatures. The scope of this review is to comprehensively lay out the general photophysics of nanographenes starting with benzene and building up to larger polycyclic aromatic hydrocarbons, GQDs, and GNRs. We also explore a collection of publications from recent years that build upon the current understanding of nanographene photophysics and their potential application in light-driven processes from display, lasing, and sensing technology to photocatalytic water splitting.

Epidemiology International

The Real-time Transport Protocol (RTP) is used to transmit media in multimedia telephony applicat... more The Real-time Transport Protocol (RTP) is used to transmit media in multimedia telephony applications. These applications are typically required to implement congestion control. This document describes the test cases to be used in the performance evaluation of such congestion control algorithms in a controlled environment.

Epidemiology International

JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH

Online Journal of Health & Allied Sciences, 2020

Introduction: Metastases to the sinonasal region is rare and presents with features overlapping w... more Introduction: Metastases to the sinonasal region is rare and presents with features overlapping with various regional neoplastic/non-neoplastic lesions. This series aims to highlight the clinical presentations and diagnostic difficulties of sinonasal metastases. Material and Method: A review of pertinent demographic and laboratory data for patients diagnosed with metastases to the sinonasal region, over a period of 6 years (2012- 2017) was done. Results and Discussion: Seven cases (males- 6, females-1) of sinonasal metastases were identified. The age ranged from 41-72 years. The common clinical presentation was nasal obstruction, epistaxis, and pain. Grossly tumors were irregular masses (mean size – 4.1cm) with maxillary sinus as the most common site. The histologic types included Squamous cell carcinoma (3 cases), clear cell renal cell carcinoma (2 cases), and one case each of infiltrating ductal carcinoma, and eccrine spiradenocarcinoma. The site of the primary tumor was larynx (2...

Journal of Krishna Institute of Medical Sciences University, 2019

Epithelioid leiomyoma is a rare variant of leiomyoma. The tumour includes three distinct entities... more Epithelioid leiomyoma is a rare variant of leiomyoma. The tumour includes three distinct entities, leiomyoblastoma, clear cell leiomyoma and plexiform leiomyoma. It is histologically characterised by epithelioid cells, clear cells or plexiform pattern in varied proportions. We report a case of a 49-year-old female with complaints of palpable mass per abdomen and spotting per vagina. Radiology revealed a complex cystic mass with obscured right ovary. She underwent total abdominal hysterectomy with bilateral salpingooophorectomy. Pathological examination showed a posterior wall lesion with central 9 × 8 cm cyst with multiple septations and surrounding rim of solid areas. Microscopic examination showed a clear cell epithelioid leiomyoma. No mitosis/tumour cell necrosis was seen. The clinical course of epithelioid leiomyoma is still unclear owing to absence of large studies. Small size, clear cell histology, mitosis of < 2/10 High Power Field (HPF) and hyalinization are features of a...

Journal of Krishna Institute of Medical Sciences University, 2020

Delta-beta Thalassemia is a rare variant of thalassemia with elevated Hb F. Heterozygous and homo... more Delta-beta Thalassemia is a rare variant of thalassemia with elevated Hb F. Heterozygous and homozygous state of delta-beta thalassemia present with features similar to Hereditary Persistence of Fetal Haemoglobin (HPFH) and beta thalassemia intermedia. Here, we describe a case of 8-month-old female child with anaemia and splenomegaly. Haemoglobin electrophoresis showed 100% HbF and no HbA and HbA2. Patient was put on haematinics and advised a repeat haemoglobin electrophoresis after completion of 1 year of age, and family screening. Hb electrophoresis of the patient at the age of 2 years mirrored the earlier findings and her father, mother and brother showed increased Hb F with normal HbA2 levels. A final diagnosis of homozygous delta-beta thalassemia in the case with sibling and parents being heterozygous delta-beta thalassemia trait was rendered. Haemoglobin electrophoresis with red cell indices forms an important diagnostic clue in differentiating delta-beta thalassemia from othe...

A MULTIPLEXER is an essential electronic device which is basically used for all kind of electroni... more A MULTIPLEXER is an essential electronic device which is basically used for all kind of electronic switching. It is commonly called as data selector. The contemporary in VLSI is demanding the need of devices which dissipates low power. Adiabatic logic family is fulfilling our demands, which dissipates low power through them. In this paper, we have studied the various adiabatic logic styles: Adiabatic dynamic CMOS logic, two phase drive adiabatic dynamic logic, Glitch free and Cascadable adiabatic logic and two phase clocked adiabatic static CMOS logic. Further, we design a 2:1 multiplexer using Static CMOS and 2PADCL logic style. The 2:1 multiplexer was designed and simulated using HSPICE with 180nm technology parameters provided by predictive technology. The 2:1 multiplexer designed using 2padcl is analyzed on the basis of average power consumed by them for various values of load capacitance, input frequency and temperature. The results are then compared with static CMOS. It is obs...

Winging of scapula occurs most commonly due to injury to long thoracic nerve supplying serratus a... more Winging of scapula occurs most commonly due to injury to long thoracic nerve supplying serratus anterior muscle. Traumatic injury to serratus anterior muscle itself is very rare. We reported a case of traumatic winging of scapula due to tear of serratus anterior muscle in a 19-year-old male. Winging was present in neutral position and in extension of right shoulder joint but not on "push on wall" test. Patient was managed conservatively and achieved satisfactory result.

The most common cause of proximal radioulnar synostosis in adults is traumatic, usually after for... more The most common cause of proximal radioulnar synostosis in adults is traumatic, usually after forearm fractures. Disabling complications are mainly loss of rotatory movements of the forearm. Various surgical procedures have been described in the literature to end up in forearm synostosis as a complication. We here presented a rare case of proximal forearm synostosis following a common but improper surgical technique for an olecranon fracture complicated by implant infection. The synostosis was treated by resection and fascia lata interposition graft.

Background: Acute pancreatitis is one of the most common abdominal pathologies having variable ou... more Background: Acute pancreatitis is one of the most common abdominal pathologies having variable outcome ranging from self limiting abdominal pain to high mortality and morbidity due to organ failure, over the past five decades, various classification systems have emerged to classify pancreatitis according to its severity , and the associated complications have emerged to classify acute pancreatitis and its various complications, such as Apache Scoring , Ct Severity , Modified Ct Severity ,Ransen and Atlanta Classification. Objectives: We in our study will be classifying patients suffering from acute pancreatitis according to the revised Atlanta classification to divide them into interstitial edematous pancreatitis and necrotizing pancreatitis. The local complications will be classified according to CT imaging findings into acute necrotic collection, psuedocyst, acute necrotic collection and walled of necrosis. Organ failure will be assessed according to modified marshal scoring syste...

Materials, Methods and Procedures: A multicenter, retrospective multicenter study was conducted o... more Materials, Methods and Procedures: A multicenter, retrospective multicenter study was conducted on patients with AF who underwent cardiac CT prior to catheter ablation between 01/01/2010 and 12/31/2015. Patients were grouped by presence or absence of prior CVA/TIA. Patients with mitral stenosis, prior mechanical aortic valve replacement, ascending aortic arch atheroma, highrisk patent foramen ovale, history of atrial septal repair or device, preexisting LAA thrombus or intra-cardiac tumor, or prior open-heart surgery were excluded. Further exclusion was performed for patients with sub-optimal or unavailable cardiac CT imaging by investigators blinded to clinical data. Blinded investigators obtained RL by measuring the distance between the left superior pulmonary venous ostium and the internal ostium of the left atrial appendage. LAA FD was calculated using semi-automated volume rendering and processing software (ImageJ, Bethesda, MD) [1] and LAA FD are presented as means (95% confid...

A heat exchanger is usually characterized by two types of thermodynamic losses. First of these tw... more A heat exchanger is usually characterized by two types of thermodynamic losses. First of these two losses is associated with the heat transfer across a finite temperature difference. The second loss is due to pressure drop due to friction in a heat exchanger. The loss associated with heat transfer across a finite temperature difference can be mitigated by increasing the heat transfer area and reducing the local temperature difference through enhancements. However, increasing the heat transfer area can lead to greater overall frictional loss and higher pressure drop. This shows that the two losses are mutually conflicting, which points to the existence of an “optimum” heat exchanger design where these two losses are minimized. The two losses can be quantified by a single number which is the total entropy generated in the heat exchanger. Total entropy generation should be minimized to arrive at an optimum heat exchanger design. In this paper, the principle of entropy generation minimi...

─ In this work a Yee’s mesh based full vectorial transverse finite difference frequency (FDFD) mo... more ─ In this work a Yee’s mesh based full vectorial transverse finite difference frequency (FDFD) modesolver has been derived from discretized Maxwell’s equations in Matrix form for anisotropic waveguides with arbitrary permittivity and permeability tensors. This work incorporates arbitrary permittivity and permeability simultaneously into matrix equations of Yee’s mesh based modesolver, which previous works have not done. For benchmarking the Python implementation of these matrix equations, cross section of Yittrium Iron Garnate (YIG) channel waveguide has been taken as first one of the three test structures. Numerical result from this work has been compared with that from previous work on YIG channel waveguide and is found to be in good agreement. Further, for benchmarking the effective index values of waveguides having both permittivity and permeability anisotropic simultaneously, a finite element based commercial software (COMSOL) has been used, the values of effective indexes from...

Sturge Weber syndrome is a type of neurocutaneous disorder also known as meningofacial angiomatos... more Sturge Weber syndrome is a type of neurocutaneous disorder also known as meningofacial angiomatosis. It is generally seen in paediatric age group and more commonly effects the males which present with delayed milestones, seizure disorder, loss of vision and other neurological deficits. Clinical suspicion of Sturge weber syndrome should be made on the presence of port wine stain(facial nevus) in a young children. MRI (magnetic resonance imaging) plays a key role in detecting the various spectrum of cortical and vascular defects associated with the syndrome. Clinicians can come to a final diagnosis of Sturge weber syndrome, when the clinical history is supplemented with MRI findings. We in our case report will be discussing the various spectrum of MR findings in this rare neurocutaneous syndrome.

In fin-and-tube heat exchangers operating at high temperatures such as Carbon Dioxide gas coolers... more In fin-and-tube heat exchangers operating at high temperatures such as Carbon Dioxide gas coolers, the heat transfer between neighboring tubes due to fin conduction affects the heat exchanger performance. In this research, a segment-by-segment heat exchanger model has been developed that can account for tube-to-tube conduction in two dimensions. The new model has been validated against experimental data for a gas cooler at 36 test conditions with total heat load varying between 6kW and 12kW. The refrigerant temperatures were measured at 27 locations on the different U-bends in the coil. The predicted heat load agreed within 3% and the refrigerant temperatures, agreed within 3.3K of measured values. The model is capable of simulating a heat exchanger that has both continuous and discontinuous i.e. cut fins. This paper investigates the effect of fin cuts on the performance of a Carbon Dioxide gas cooler through an exhaustive search method. In this approach, tubes are progressively sep...

Photosynthesis Research

Graphene quantum dots (GQDs) and nanoribbons (GNRs) are classes of nanographene molecules that ex... more Graphene quantum dots (GQDs) and nanoribbons (GNRs) are classes of nanographene molecules that exhibit highly tunable photophysical properties. There have been great strides in recent years to advance our understanding of nanographene photophysics and develop their use in light-harvesting systems, such as artificial photosynthesis. Here, we review the latest studies of GQDs and GNRs which have shed new light onto their photophysical underpinnings through computational and advanced spectroscopic techniques. We discuss how the size, symmetry, and shape of nanographenes influence their molecular orbital structures and, consequentially, their spectroscopic signatures. The scope of this review is to comprehensively lay out the general photophysics of nanographenes starting with benzene and building up to larger polycyclic aromatic hydrocarbons, GQDs, and GNRs. We also explore a collection of publications from recent years that build upon the current understanding of nanographene photophysics and their potential application in light-driven processes from display, lasing, and sensing technology to photocatalytic water splitting.

Epidemiology International

The Real-time Transport Protocol (RTP) is used to transmit media in multimedia telephony applicat... more The Real-time Transport Protocol (RTP) is used to transmit media in multimedia telephony applications. These applications are typically required to implement congestion control. This document describes the test cases to be used in the performance evaluation of such congestion control algorithms in a controlled environment.

Epidemiology International

JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH