Sharif Digital Repository

This paper is concerned with global analysis of a delay SVEIR epidemiological model in a population of varying size. By using Lyapunov stability method and LaSalle's invariance principle for delay systems, we prove that when there is no endemic equilibrium, the disease free equilibrium is globally asymptotically stable, otherwise the endemic equilibrium is globally stable  

Intensity-modulated radiation therapy is a well-known technique for treating cancer patients worldwide. A treatment plan in this technique requires decision-making for three main problems: selection of beam angles, intensity map calculation, and leaf sequencing. Previous works investigated these problems sequentially. We present a new integrated framework for simultaneous decision-making of directions, intensities, and aperture shape, called direct angle and aperture optimization, and develop a mixed-integer nonlinear mathematical model for the problem. Due to the nonlinearity and the dimension of the problem, three efficient metaheuristics based on differential evolution (DE) called classic... 

Background: While decoding visual and auditory stimuli using recorded EEG signals has enjoyed significant attention in the past decades, decoding olfactory sensory input from EEG data remains a novelty. Recent interest in the brain's mechanisms of processing olfactory stimuli partly stems from the association of the olfactory system and its deficit with neurodegenerative diseases. New Methods: An olfactory stimulus decoder using features that represent nonlinear behavior content in the recorded EEG data has been introduced for classifying 4 olfactory stimuli in 5 healthy male subjects. Results: We show that by using nonlinear and chaotic features, a subject-specific classifier can be... 

Human parvovirus B19 (B19) is a small, non-enveloped virus and belongs to Parvoviridae family. B19 persists in many tissues such as thyroid tissue and even thyroid cancer. The main aim of this study was to determine the presence of B19, its association with increased inflammation in thyroid tissue, and thus its possible role in thyroid cancer progression. Studies have shown that virus replication in non-permissive tissue leads to overexpression of non-structural protein and results in upregulation of proinflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha. A total of 36 paraffin-embedded thyroid specimens and serum were collected from patients and 12 samples were used... 

Background: Stomach cancer is a major health problem in many countries. Understanding the current burden of stomach cancer and the differential trends across various locations is essential for formulating effective preventive strategies. We report on the incidence, mortality, and disability-adjusted life-years (DALYs) due to stomach cancer in 195 countries and territories from 21 regions between 1990 and 2017. Methods: Estimates from GBD 2017 were used to analyse the incidence, mortality, and DALYs due to stomach cancer at the global, regional, and national levels. The rates were standardised to the GBD world population and reported per 100 000 population as age-standardised incidence rates,... 

Background. Autoimmune process and immunosuppressive therapy of pemphigus vulgaris would predispose the patients to infections. Aim. We aimed to study the prevalence of infection and pathogenic agents in pemphigus vulgaris patients admitted to dermatology service. Material and methods. This retrospective study was conducted on 155 pemphigus vulgaris patients (68 males, 87 females) admitted to dermatology service between 2009 and 2011. In this study, the diagnosis of pemphigus vulgaris was confirmed by light microscopic and direct immunofluorescence findings. Data were collected through a questionnaire. Results. Of 155 pemphigus vulgaris patients, 33 had infection at admission and 9 acquired... 

The increasing importance of nanotechnology in the field of biomedical applications has encouraged the development of new nanomaterials endowed with multiple functions. Novel nanoscale drug delivery systems with diagnostic, imaging and therapeutic properties hold many promises for the treatment of different types of diseases, including cancer, infection and neurodegenerative syndromes. Carbon nanotubes (CNTs) are both low-dimensional sp2 carbon nanomaterials exhibiting many unique physical and chemical properties that are interesting in a wide range of areas including nanomedicine. Since 2004, CNTs have been extensively explored as drug delivery carriers for the intracellular transport of... 

The aim of this work was to synthesize molecularly imprinted polymer-poly ethylene glycol-folic acid (MIP-PEG-FA) nanoparticles for use as a controlled release carrier for targeting delivery of paclitaxel (PTX) to cancer cells. MIP nanoparticles were synthesized by a mini-emulsion polymerization technique and then PEG-FA was conjugated to the surface of nanoparticles. Nanoparticles showed high drug loading and encapsulation efficiency, 15.6 ± 0.8 and 100%, respectively. The imprinting efficiency of MIPs was evaluated by binding experiments in human serum. Good selective binding and recognition were found in MIP nanoparticles. In vitro drug release studies showed that MIP-PEG-FA have a... 

Aim of study: Glioblastoma Multiforme (GBM) is an aggressive brain cancer in adults that kills most patients in the first year due to ineffective treatment. Different clinical, biomedical, and image data features are needed to analyze GBM, increasing complexities. Besides, they lead to weak performances for machine learning models due to ignoring physicians' knowledge. Therefore, this paper proposes a hierarchical model based on Fuzzy C-mean (FCM) clustering, Wrapper feature selection, and twelve classifiers to analyze treatment plans. Methodology/Approach: The proposed method finds the effectiveness of previous and current treatment plans, hierarchically determining the best decision for... 

Purpose: The accuracy of pedicle screw placement during image-guided spine surgery (IGSS) can be characterized by estimating the target registration error (TRE). The major factors that influence TRE were identified, minimized, and verified with in vitro experiments. Materials and methods: Computed-tomography- compatible markers are placed over anatomical landmarks of lumbar vertebral segments in locations that are feasible and routinely used in surgical procedures. TRE was determined directly for markers placed on the pedicles of vertebra segments. First, optimum selections of landmarks are proposed for different landmarks according to the minimum achievable TRE values in different... 

A novel and high potent magnetic nanobiocomposite was prepared based on Carboxymethyl cellulose (CMC) and epichlorohydrin (ECH) cross-linker interactions to form a three-dimensional cross-linked CMC hydrogel followed by silk fibroin (SF) and halloysite nanotubes (HNTs) modifications and further in situ Fe3O4 magnetic nanoparticles (MNPs) formation. Different analytical techniques like FT-IR, EDX, FE-SEM, XRD, TGA, and VSM were used to characterize the structure of the prepared nanobiocomposite. The spherical morphology of Fe3O4 MNPs and tubular HNTs were presented in the FE-SEM images. In biological tests, since the hemolysis percent was even less than the negative control, the CMC... 

Herniation in the lumbar area is one of the most common diseases which results in lower back pain (LBP) causing discomfort and inconvenience in the patients' daily lives. A computer aided diagnosis (CAD) system can be of immense benefit as it generates diagnostic results within a short time while increasing precision of diagnosis and eliminating human errors. We have proposed a new method for automatic diagnosis of lumbar disc herniation based on clinical MRI data. We use T2-W sagittal and myelograph images. The presented method has been applied on 30 clinical cases, each containing 7 discs (210 lumbar discs) for the herniation diagnosis. We employ Otsu thresholding method to extract the... 

This study investigated the effects of different patterns of coronary artery tortuosity (CAT) on the stress concentration of the plaques and the blood flow pattern inside an atherosclerotic artery to predict the risk of plaque rupture and progression. Four different loadings of the coronary artery, including pulsatile blood pressure as well as one-end twist around the artery axis at blood pressures of 74, 100, and 120 mmHg were considered. No study has addressed bent and twist buckling of an atherosclerotic artery considering pulsatile flow (for bent buckling), fluid-solid interaction, and different geometrical parameters of the plaque. The results showed that C-shape tortuosity under... 

Viral diseases have long been among the biggest challenges for healthcare systems around the world. The recent Coronavirus Disease 2019 (COVID-19) pandemic is an example of how complicated the situation can get if we are not prepared to combat a viral outbreak in time, which brings up the need for quick and affordable biosensing platforms and vast knowledge of potential antiviral effects and drug/gene delivery opportunities. The same challenges have also existed for nonviral immunogenic disorders. Nanomedicine is considered a novel candidate for effectively overcoming these worldwide challenges. Among the versatile nanomaterials commonly used in biomedical applications, graphene has recently... 

Prostate cancer (PCa), the second most malignant neoplasm in men, is also the fifth leading cause of cancer-related deaths in men globally. Unfortunately, this malignancy remains largely asymptomatic until late-stage emergence when treatment is limited due to the lack of effective metastatic PCa therapeutics. Due to these limitations, early PCa detection through prostate-specific antigen (PSA) screening has become increasingly important, resulting in a more than 50% decrease in mortality. Conventional assays for PSA detection, such as enzyme-linked immunosorbent assay (ELISA), are labor intensive, relatively expensive, operator-dependent and do not provide adequate sensitivity.... 

Recent progress in the areas of network science and control has shown a significant promise in understanding and analyzing epidemic processes. A well-known model to study epidemics processes used by both control and epidemiological research communities is the susceptible–infected–susceptible (SIS) dynamics to model the spread of disease/viruses over contact networks of infected and susceptible individuals. The SIS model has two metastable equilibria: one is called the endemic equilibrium and the other is known as the disease-free or healthy-state equilibrium. Control theory provides the tools to design control actions (allocating curing or vaccination resources) in order to achieve and... 

Introduction: Today, Fuzzy expert systems have helped physicians in cases of uncertainty in medical decision making for prescribing drugs. Narrowing of coronary heart and reduction in heart blood flow are important causes of coronary heart disease (CHD). Control of blood lipid level is a routine treatment in CHD patients. But damage to liver is a common side effect of lipid lowering drug medication. Measurement of plasma Alanine aminotransferase level is considered as a marker of liver damage. The aim of this study was to determination of optimal dose of atorvastatin using Fuzzy expert system. Materials and Methods: in this study, Fuzzy expert system based on drug dose determination was... 

Separation and isolation of suspended submicron particles is fundamental to a wide range of applications, including desalination, chemical processing, and medical diagnostics. Ion concentration polarization (ICP), an electrokinetic phenomenon in micro-nano interfaces, has gained attention due to its unique ability to manipulate molecules or particles in suspension and solution. Less well understood, though, is the ability of this phenomenon to generate circulatory fluid flow, and how this enables and enhances continuous particle capture. Here, we perform a comprehensive study of a low-voltage ICP, demonstrating a new electrokinetic method for extracting submicron particles via flow-enhanced... 

Background: Air pollutants have not been associated with ambulatory electrocardiographic evidence of ST-segment depression ≥ 1 mm (probable cardiac ischemia). We previously found that markers of primary (combustion-related) organic aerosols and gases were positively associated with circulating biomarkers of inflammation and ambulatory blood pressure in the present cohort panel study of elderly subjects with coronary artery disease. Objectives: We specifically aimed to evaluate whether exposure markers of primary organic aerosols and ultrafine particles were more strongly associated with ST-segment depression of ≥ 1 mm than were secondary organic aerosols or PM 2.5 (particulate matter with... 

Apathy is a stressor and debilitating common condition for both stroke survivors and their caregivers. However, its effects on the postural control of these patients have not yet been investigated. Improved postural stability through withdrawing attention from postural control by concurrent cognitive task (i.e. dual-task condition) has been reported previously, but the effect of apathy, as a confounding factor, remains unknown. This study aimed to examine the effects of apathy and dual-task condition on postural control of chronic stroke survivors from biomechanical and neurophysiological perspectives. Twenty non-apathetic stroke survivors, 20 apathetic stroke survivors, and 20 sex-, age-,...