Tensor Networks for Medical Image Classification

With the increasing adoption of machine learning tools like neural networks across several domains, interesting connections and comparisons to concepts from other domains are coming to light. In this work, we focus on the class of Tensor Networks, which has been a work horse for physicists in the last two decades to analyse quantum many-body systems. Building on the recent interest in tensor networks for machine learning, we extend the Matrix Product State tensor networks (which can be interpreted as linear classifiers operating in exponentially high dimensional spaces) to be useful in medical image analysis tasks. We focus on classification problems as a first step where we motivate the use of tensor networks and propose adaptions for 2D images using classical image domain concepts such as local orderlessness of images. With the proposed locally orderless tensor network model (LoTeNet), we show that tensor networks are capable of attaining performance that is comparable to state-of-the-art deep learning methods. We evaluate the model on two publicly available medical imaging datasets and show performance improvements with fewer model hyperparameters and lesser computational resources compared to relevant baseline methods.Comment: Accepted for publication at International Conference on Medical Imaging with Deep Learning (MIDL), 2020. Reviews on Openreview here: https://openreview.net/forum?id=jjk6bxk07

Lung Segmentation from Chest X-rays using Variational Data Imputation

Pulmonary opacification is the inflammation in the lungs caused by many respiratory ailments, including the novel corona virus disease 2019 (COVID-19). Chest X-rays (CXRs) with such opacifications render regions of lungs imperceptible, making it difficult to perform automated image analysis on them. In this work, we focus on segmenting lungs from such abnormal CXRs as part of a pipeline aimed at automated risk scoring of COVID-19 from CXRs. We treat the high opacity regions as missing data and present a modified CNN-based image segmentation network that utilizes a deep generative model for data imputation. We train this model on normal CXRs with extensive data augmentation and demonstrate the usefulness of this model to extend to cases with extreme abnormalities.Comment: Accepted to be presented at the first Workshop on the Art of Learning with Missing Values (Artemiss) hosted by the 37th International Conference on Machine Learning (ICML). Source code, training data and the trained models are available here: https://github.com/raghavian/lungVAE

Locally orderless tensor networks for classifying two- and three-dimensional medical images

Tensor networks are factorisations of high rank tensors into networks of lower rank tensors and have primarily been used to analyse quantum many-body problems. Tensor networks have seen a recent surge of interest in relation to supervised learning tasks with a focus on image classification. In this work, we improve upon the matrix product state (MPS) tensor networks that can operate on one-dimensional vectors to be useful for working with 2D and 3D medical images. We treat small image regions as orderless, squeeze their spatial information into feature dimensions and then perform MPS operations on these locally orderless regions. These local representations are then aggregated in a hierarchical manner to retain global structure. The proposed locally orderless tensor network (LoTeNet) is compared with relevant methods on three datasets. The architecture of LoTeNet is fixed in all experiments and we show it requires lesser computational resources to attain performance on par or superior to the compared methods.Comment: Accepted for publication at the Journal of Machine Learning for Biomedical Imaging (MELBA) (see https://melba-journal.org). Source code at https://github.com/raghavian/LoTeNet_pytorch

Iron environment non-equivalence in both octahedral and tetrahedral sites in NiFe2O4 nanoparticles: study using Mössbauer spectroscopy with a high velocity resolution

Mössbauer spectrum of NiFe2O4 nanoparticles was measured at room temperature in 4096 channels. This spectrum was fitted using various models, consisting of different numbers of magnetic sextets from two to twelve. Non-equivalence of the 57Fe microenvironments due to various probabilities of different Ni2+ numbers surrounding the octahedral and tetrahedral sites was evaluated and at least 5 different microenvironments were shown for both sites. The fit of the Mössbauer spectrum of NiFe 2O4 nanoparticles using ten sextets showed some similarities in the histograms of relative areas of sextets and calculated probabilities of different Ni2+ numbers in local microenvironments. © 2012 American Institute of Physics

Comparative study of PUVA Therapy Versus Narrow Band UVB Therapy in the treatment of Vitiligo

INTRODUCTION : Vitiligo is an ‘idiopathic’ acquired depigmenting disorder characterized by the loss of functional melanocytes from the epidermis. It is the most common pigmentary disorder and it involves complex interaction of environmental and genetic factors that ultimately contribute to melanocytes destruction, resulting in the characteristic depigmented lesions. Vitiligo can be extremely disfiguring, leading to significant patient morbidity. Low self esteem, poor body image and poor quality of life has been found in patients with vitiligo, including significant psychiatric morbidity. This is of particular concern for children and adolescents, as they are in their formative years and developing their sense of self. Vitiligo is perhaps the most frequent depigmenting disorder, occurring with a prevalence varying across populations, apparently being less frequent in Caucasians (0.38%), African (0.34%), and Chinese[6] (0.0093%) than in Indians (0.46–1.13%). Not so commonly, higher prevalence may appear among isolated populations. Its pathogenesis has been associated with genetic predisposition, autoimmune phenomenon and neural and growth factor dysregulation as well as inherent cellular metabolic defects leading to melanocyte apoptosis. The phenotypical expression of vitiligo is polymorphic, and several types of vitiligo are distinguished on clinical presentation. The natural course of vitiligo is gradual, unpredictable and difficult to control. However, sometimes the disease persists in a stable status for a long time. Vitiligo possess a treatment challenge and will remain so until we find treatments that give consistent, and long-term cure by repigmentation. Several treatment modalities have been advocated including topical therapy with potent topical corticosteroids, calcipotriol, tacrolimus, pseudocatalase therapy and other modalities like melanocyte transplantation, skin grafting, cosmetic camouflage or self tanning preparations and psychological therapy. But these are often unsatisfactory for generalised Vitiligo, for which NB UVB and PUVA are the most important therapies. In 1974, Parish successfully introduced a treatment combining 8- methoxypsoralen and UVA called PUVA using newly developed Henselar high intensity artificial UVA light. The combination treatment of Psoralen with ultraviolet A (PUVA) therapy is a standardised therapy for vitiligo and is still the mainstay for non segmental vitiligo. Interestingly two-thirds of patients receiving psoralens and ultraviolet light found the treatment worthwhile, meaning that even if treatments are only partially effective, they may achieve psychosocial relief. The clinical studies with NBUVB in vitiligo are few. Earlier reported studies were mostly done in the western population and the studies in the darker race, including Indians, is limited. Narrow-band ultraviolet B (NBUVB) is an emerging, effective and safe therapy for vitiligo. It is as effective as PUVA without many side effects. In 1997, Westerhof and Nieuweboer-Krobotova were the first to study the effect of NBUVB in vitiligo. NBUVB therapy has also been reported to be safe in childhood Vitiligo. Recent reports have shown that NBUVB can induce significant repigmentation in either generalized or segmental vitiligo. It inhibits the induction and secretion of cytokines, and stimulates inactive melanocytes in the outer root sheath of hair follicles to proliferate and migrate into vitiligo lesions. In comparing the treatment of vitiligo with NBUVB radiation versus topical PUVA, Westerhof concluded that UVB therapy was slightly more effective, produced faster repigmentation and had fewer side-effects. However, narrowband UVB therapy is not readily available and implies significant start-up expenses. There are only few studies to compare the safety and efficacy of NBUVB therapy & PUVA therapy in the treatment of vitiligo. More number of studies to compare the same is required. Hence this prospective study is conducted. AIMS OF THE STUDY : To compare the efficacy and safety of PUVA therapy and NBUVB therapy in the treatment of Vitiligo vulgaris in terms of • Time taken for initial repigmentation. • Mean grade of treatment response. • Colour match. • Psychological satisfaction. • Side effects. MATERIALS AND METHODS : This randomised open prospective clinical study was conducted on forty Vitiligo vulgaris patients who attended outpatient clinic of Dermatology department at Tirunelveli medical college hospital, Tirunelveli over the period of 15 months from April 2009 to June 2010. Approval was obtained from the institutional ethical committee prior to the conduct of this study. PATIENT SELECTION : Inclusion criteria: a. Age 18 to 65 years. b. Body surface area involvement greater than 10%. c. Stable Vitiligo (Stable for more than one year). Exclusion criteria: a. Age less than18 years and more than 65 years. b. Body surface area involvement lesser than 10%. c. H/o Photosensitivity and Photo mediated disorders. d. H/o administration of drugs causing photosensitization. e. H/o skin malignancy, renal and hepatic diseases. f. Pregnancy and Lactation. g. Active Vitiligo. h. Patient on any treatment for Vitiligo within previous 6 months. The name, age, sex, address, outpatient number were noted. Following detailed clinical history was taken. 1. Time of onset of Vitiligo. 2. Course of the disease-stability and rate of progression. 3. Potential precipitating events including emotional stress and cutaneous Trauma. 4. History of photosensitivity and drug causing photosensitivity. 5. History of any treatment(Systemic, topical). 6. Any history of suggestive of Diabetes Mellitus, Hypertension, Thyroid disease, Anaemia and other autoimmune diseases. 7. Family history of Vitiligo. 8. History of any psychological impact by the Vitiligo. All patients were examined under good light. Detailed dermatological examination including size, shape, number, color and distribution of lesions was done. Pattern of Vitiligo and mucosal involvements were taken into account. Presence of leucotrichia in the patch was also noted. Estimation of percentage of body surface area with Vitiligo was carried out by using rule of 9 (Wallace), 9% for head and neck (head 7%, neck 2%), 9% for each upper limb (arm 4%, forearm 3% hand 2%) 9% for the front of each lower limb (Thigh 5%, leg 2.5%, foot1.5 %) and 9% for the back of each lower limb (Thigh 5%, leg 2.5%, foot1.5 %). 9% for the front of chest, 9% for the front of the abdomen, 9% for the upper back, 9% for the lower back and 1% for the external genitalia. Palm size is taken as about 1% of body surface area for measuring small area of involvement. Any skin lesions suggestive of autoimmune disorders like Autoimmune thyroiditis, Diabetes mellitus, pernicious anaemia, Addison’s disease if present were noted. Laboratory investigations like routine blood examination (Hb, TC, DC & ESR), urine analysis, blood sugar, blood urea and serum creatinine, liver function tests, thyroid function test were done. ophthalmic examination was done to rule out cataract and retinal pathology Initial photographs were taken using canon digital camera before commencement of treatment, completion of every sixteen treatment sessions and at the end of the treatment. Patients were randomly allocated to receive either PUVA or narrow band UVB by means of a sequentially numbered list Treatment schedule, precaution to be taken during and after treatment, expected response, total duration of treatment and common side effects were explained to the patient. Informed consent was obtained from the patients before starting treatment. CONCLUSION : The NBUVB groups showed better response in all the treatment response parameter compared. There was a statistically significant improvement seen in mean grade of treatment response at the end of treatment and the colour match. In the treatment of vitiligo NBUVB therapy is superior to PUVA therapy. However studies with larger group of patient and longer duration of treatment and follow up are essential to reveal further differences or to confirm the result of this study

Comparative Study on Kinetic Parameters for Tranesterification of Pongamia and Cotton Seed Oil

Abstract: Tranesterification of pongamia and cotton seed oil were performed at various experimental conditions such as temperature, molar ratio, catalyst concentration, reaction time and stirring speed. Maximum yield of around 85 % was obtained for pongamia and cotton seed oil at optimum conditions of temperature (338 K), molar ratio of methanol to oil (6:1), cation exchange resin catalyst (1.5 wt. %), stirring speed (10 Hz) and reaction time of 3 h. Kinetics of tranesterified pongamia and cotton seed oil were studied using Arrhenius plot. In excess of methanol, the transesterification reaction follows pseudo-first order reaction. The activation energies of pongamia and cotton seed oil were found to be 41570 and 23694.9 J/mol respectively. Kinetic study revealed that cotton seed oil is best suited for the maximum yield of biodiesel production

The liquidity impact on bond calculation on credit losses : a Malaysian banks’ perspective

Purpose: The aim of this paper is to empirically determine the stance of the Nigerian financial sector in absorbing or intensifying trade shocks. Design/Methodology/Approach: Towards achieving this objective, the study uses Auto-Regressive Distributed Lag (ARDL) technique to analyse annual data from 1981 to 2017. Data used in this study were sourced from Central Bank of Nigeria Statistical Bulletin and Statista. Findings: Major finding from the long-run result shows that financial development intensifies trade-led shocks, there by yielding to output volatility. Practical implication: Based on findings, the study recommends the Nigerian government to focus on the achievement of greater and more inclusive financial development. This can be achieved through; increasing the availability and affordability of financial services, easing access to loans, improving soundness of banks and fostering legal traditions that protect creditors and investors. Originality/Value: In addition to the lack of available literature with focus on this subject in the Nigerian sphere, understanding the role of Nigerian financial sector in absorbing trade-led shocks is fundamental in optimizing Nigeria’s benefits from trade. This is of utmost importance, particularly in a time where the nation just signed the Africa Continental Free Trade Agreement.peer-reviewe

Evaluation of a novel phantom for the quality assurance of a six-degree-of-freedom couch 3D-printed at multiple centres

This study aimed to validate a bespoke 3D-printed phantom for use in quality assurance (QA) of a 6 degrees-of-freedom (6DoF) treatment couch. A novel phantom design comprising a main body with internal cube structures, was fabricated at five centres using Polylactic Acid (PLA) material, with an additional phantom produced incorporating a PLA-stone hybrid material. Correctional setup shifts were determined using image registration by 3D-3D matching of high HU cube structures between obtained cone-beam computer tomography (CBCT) images to reference CTs, containing cubes with fabricated rotational offsets of 3.5°, 1.5° and −2.5° in rotation, pitch, and roll, respectively. Average rotational setup shifts were obtained for each phantom. The reproducibility of 3D-printing was probed by comparing the internal cube size as well as Hounsfield Units between each of the uniquely produced phantoms. For the five PLA phantoms, the average rot, pitch and roll correctional differences from the fabricated offsets were −0.3 ± 0.2°, −0.2 ± 0.5° and 0.2 ± 0.3° respectively, and for the PLA hybrid these differences were −0.09 ± 0.14°, 0.30 ± 0.00° and 0.03 ± 0.10°. There was found to be no statistically significant difference in average cube size between the five PLA printed phantoms, with the significant difference (P < 0.05) in HU of one phantom compared to the others attributed to setup choice and material density. This work demonstrated the capability producing a novel 3D-printed 6DoF couch QA phantom design, at multiple centres, with each unique model capable of sub-degree couch correction

ANALYSIS OF VARIABLE SPEED PFC CHOPPER FED BLDC MOTOR DRIVE

ABSTRACT This paper provides the detailed analysis of the DC-DC chopper fed Brushless DC motor drive used for lowpower applications. The various methods used to improve the power quality at the ac mains with lesser number of components are discussed. The most effective method of power quality improvement is also simulated using MATLAB Simulink. Improved method of speed control by controlling the dc link voltage of Voltage Source Inverter is also discussed with reduced switching losses. The continuous and discontinuous modes of operation of the converters are also discussed based on the improvement in power quality. The performance of the most effective solution is simulated in MATLAB Simulink environment and the obtained results are presented

Numerical investigation of heat transfer enhancement in solar air heaters using polygonal-shaped ribs and grooves

Solar air heating thermal systems have found extensive utilization in a broad array of industrial and residential settings, playing a pivotal role in the conversion and reclamation of solar energy. Implementing repeated artificial roughness in the surfaces has the potential to augment thermal performance in solar air heaters (SAHs). This study presents a numerical investigation of SAHs with artificial rough surfaces, consisting of polygonal-shaped ribs and grooves located at different places inside the rectangular duct, that improve thermal efficiency. ANSYS Fluent software was employed to simulate the SAH with different relative pitch distances of p = 10 mm and 20 mm and relative rib heights e/d = 0.09–0.045. The working fluid air flows at different Reynolds numbers (Re), ranging from 3,800 to 18,000. Nusselt number (Nu), friction factor (f), and Thermal Hydraulic Performance (THP) are parameters to evaluate the performance of the SAH. The renormalized group (RNG) k-ϵ turbulent model was implemented in this simulation. The study outcomes indicate that increasing the rib height improves the heat transfer rate and nonetheless increases pressure drop while increasing the pitch distance. The higher Nusselt number (Nu) is 3.762 attained at p = 10 mm and 3.420 at p = 20 mm in the center-positioned rib at Re 3,800. The lower friction factor (ƒ) obtained in p = 20 mm is 1.681 and 0.785 in p = 10 mm in the staggered positioned rib at higher Re 15,000. The optimal THP was achieved at 2.813 at a staggered rib height at a pitch distance of p = 10 mm at Re 8,000. The study’s findings suggest that the incorporation of artificial rough surfaces has the potential to enhance the THP of an SAH