Inference for the Rayleigh Distribution Based on Progressive Type-II Fuzzy Censored Data

Classical statistical analysis of the Rayleigh distribution deals with precise information. However, in real world situations, experimental performance results cannot always be recorded or measured precisely, but each observable event may only be identified with a fuzzy subset of the sample space. Therefore, the conventional procedures used for estimating the Rayleigh distribution parameter will need to be adapted to the new situation. This article discusses different estimation methods for the parameters of the Rayleigh distribution on the basis of a progressively type-II censoring scheme when the available observations are described by means of fuzzy information. They include the maximum likelihood estimation, highest posterior density estimation and method of moments. The estimation procedures are discussed in detail and compared via Monte Carlo simulations in terms of their average biases and mean squared errors. Finally, one real data set is analyzed for illustrative purposes

Leveraging Optimal Transport for Enhanced Offline Reinforcement Learning in Surgical Robotic Environments

Most Reinforcement Learning (RL) methods are traditionally studied in an active learning setting, where agents directly interact with their environments, observe action outcomes, and learn through trial and error. However, allowing partially trained agents to interact with real physical systems poses significant challenges, including high costs, safety risks, and the need for constant supervision. Offline RL addresses these cost and safety concerns by leveraging existing datasets and reducing the need for resource-intensive real-time interactions. Nevertheless, a substantial challenge lies in the demand for these datasets to be meticulously annotated with rewards. In this paper, we introduce Optimal Transport Reward (OTR) labelling, an innovative algorithm designed to assign rewards to offline trajectories, using a small number of high-quality expert demonstrations. The core principle of OTR involves employing Optimal Transport (OT) to calculate an optimal alignment between an unlabeled trajectory from the dataset and an expert demonstration. This alignment yields a similarity measure that is effectively interpreted as a reward signal. An offline RL algorithm can then utilize these reward signals to learn a policy. This approach circumvents the need for handcrafted rewards, unlocking the potential to harness vast datasets for policy learning. Leveraging the SurRoL simulation platform tailored for surgical robot learning, we generate datasets and employ them to train policies using the OTR algorithm. By demonstrating the efficacy of OTR in a different domain, we emphasize its versatility and its potential to expedite RL deployment across a wide range of fields.Comment: Preprin

A Survey of Imitation Learning: Algorithms, Recent Developments, and Challenges

In recent years, the development of robotics and artificial intelligence (AI) systems has been nothing short of remarkable. As these systems continue to evolve, they are being utilized in increasingly complex and unstructured environments, such as autonomous driving, aerial robotics, and natural language processing. As a consequence, programming their behaviors manually or defining their behavior through reward functions (as done in reinforcement learning (RL)) has become exceedingly difficult. This is because such environments require a high degree of flexibility and adaptability, making it challenging to specify an optimal set of rules or reward signals that can account for all possible situations. In such environments, learning from an expert's behavior through imitation is often more appealing. This is where imitation learning (IL) comes into play - a process where desired behavior is learned by imitating an expert's behavior, which is provided through demonstrations. This paper aims to provide an introduction to IL and an overview of its underlying assumptions and approaches. It also offers a detailed description of recent advances and emerging areas of research in the field. Additionally, the paper discusses how researchers have addressed common challenges associated with IL and provides potential directions for future research. Overall, the goal of the paper is to provide a comprehensive guide to the growing field of IL in robotics and AI.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Effect of garlic (Allium sativum) on lipid profiles, antioxidant activity and expression of scavenger receptor class B type I (SR-BI) in liver and intestine of hypercholesterolemic mice

Garlic is one of the medicinal plants, which has shown many useful effects, including Antioxidant activity, hypolipidemic and hypocholesterolemic effects, anti-hypertensive and anti-diabetic effects. Scavenger receptor class B type I (SR-BI) is a cell-surface receptor which mediated selective cholesterol ester uptake from the HDL particle. SR-BI also has an important role in cholesterol absorption in the intestine.  Animals were randomly divided into three groups (n=8); group 1:  received chow + cholesterol (2%) + cholic acid (0.5%), group 2: chow + 4% (w/w) garlic extract + cholesterol (2%) + cholic acid (0.5%), and group 3: chow only. After one-month mice were sacrificed, blood was collected; lipid profile and blood glucose were determined enzymatically as well as mRNA and protein levels of SR-BI were determined by RT-PCR and westernblot respectively. Compared with hypercholesterolemic control, garlic extract significantly decreased total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides, Very Low-Density Lipoprotein-Cholesterol (VLDL-C) and  atherogenic index (all of them P<0.05). The activity of  Super oxide dismutase(SOD), glutathione (GSH)  and catalase levels were markedly increased in garlic-treated animals compared with hypercholesterolemic animals (p<0.05). The plasma levels of MDA markedly reduced in garlic group compared with hypercholesterolemic group. Intestinal SR-BI mRNA and protein were significantly decreased in garlic extract mice treatment compared with hypercholesterolemic control. Levels of liver SR-BI protein significantly reduced in hypercholesterolemic group (P<0.05). In conclusion, garlic extract markedly reduced TC, LDL-C, TG, VLDL-C and atherogenic index, as compared with the hypercholesterolemic control group. On the other hand garlic extract led to down-regulation of SR-BI protein and mRNA in the intestine of mice

The effect of sodium thiopental as a GABA mimetic drug in neonatal period on expression of GAD65 and GAD67 genes in hippocampus of newborn and adult male rats

Objective(s): Development of the nervous system in human and most animals is continued after the birth. Critical role of this period in generation and specialization of the neuronal circuits is confirmed in numerous studies. Any pharmacological intervention in this period may result in structural, functional or behavioral abnormalities. In this study, sodium thiopental a GABA mimetic drug was administrated to newborn rats and their GAD65 and GAD67 expression in hippocampus was evaluated before and after puberty. Materials and Methods: Newborn male Wistar rats were received sodium thiopental (35 mg/kg) daily for 11 days (from 4 to 14 days after birth). Expression of GAD65 and GAD67 in their hippocampus was compared with control groups in 15 and 45 days after birth with RT-qPCR method. Results: Significant down regulation of GAD65 and GAD67 gene expression was observed in treated rats compared with control group in 45 days after birth animals. But no significant difference was shown between experimental and control groups 15 days after birth animals. Conclusion: The effect of sodium thiopental on GAD65 and GAD67 expression only at adult rats showed a latent period of influence which can be attributed to dosage or intension of sodium thiopental neurotoxicity. Significant down regulation of GAD65 and GAD67 showed unwanted effect of sodium thiopental as GABA mimetic drug in critical period of development

Equine Adipose-Derived Mesenchymal Stem Cells: Phenotype and Growth Characteristics, Gene Expression Profile and Differentiation Potentials

Objective: Because of the therapeutic application of stem cells (SCs), isolation and characterization of different types of SCs, especially mesenchymal stem cells (MSCs), have gained considerable attention in recent studies. Adipose tissue is an abundant and accessible source of MSCs which can be used for tissue engineering and in particular for treatment of musculoskeletal disorders. This study was aimed to isolate and culture equine adipose-derived MSCs (AT-MSCs) from little amounts of fat tissue samples and determine some of their biological characteristics. Materials and Methods: In this descriptive study, only 3-5 grams of fat tissue were collected from three crossbred mares. Immediately, cells were isolated by mechanical means and enzymatic digestion and were cultured in optimized conditions until passage 3 (P3). The cells at P3 were evaluated for proliferative capacities, expression of specific markers, and osteogenic, chondrogenic and adipogenic differentiation potentials. Results: Results showed that the isolated cells were plastic adherent with a fibroblast-like phenotype. AT-MSCs exhibited expression of mesenchymal cluster of differentiation (CD) markers (CD29, CD44 and CD90) and not major histocompatibility complex II (MHC-II) and CD34 (hematopoietic marker). Cellular differentiation assays demonstrated the chondrogenic, adipogenic and osteogenic potential of the isolated cells. Conclusion: Taken together, our findings reveal that equine MSCs can be obtained easily from little amounts of fat tissue which can be used in the future for regenerative purposes in veterinary medicine

Determinants of perivascular adipose tissue stranding as a novel imaging marker and its relation to inflammatory biomarker high-sensitivity C-reactive protein

Purpose: This study aimed to examine the relationship of perivascular adipose tissue (PVAT) stranding in coronary computed tomography angiography (CCTA) with high-sensitivity C-reactive protein (hsCRP) and the determinants of PVAT stranding in coronary artery disease (CAD) patients. Material and methods: This retrospective cross-sectional study was done by collecting data from CAD patients who were referred to Rajaie Cardiovascular Centre between January 2018 and September 2020, with CCTA and hsCRP test 72 hours apart from the CCTA. PVAT stranding was defined as irregular obscuration of PVAT adjacent to the coronary arteries. An attempt was made to find a correlation between included variables and PVAT stranding by comparing them between 2 groups: patients with and without PVAT stranding. Results: From 92 patients, 31 participants had PVAT stranding, and statistically significant higher levels of hsCRP were detected in them (p = 0.007). We demonstrated significantly higher prevalence of history of hyperlipidaemia (OR = 3.83, p = 0.029), high-risk plaque features (OR = 11.80, p = 0.015), and obstructive coronary luminal stenosis (OR = 3.25, p = 0.025) in patients with PVAT stranding. Also, significantly higher PVAT attenuation was detected in patients with PVAT stranding (p < 0.001) independently from mean attenuation of epicardial fat. Conclusion: PVAT stranding could be used as a novel non-invasive marker in CCTA of CAD patients. More studies focusing on patient outcomes are required to better evaluate the reliability and prognostic value of this marker

Sagittal Balance Concept and Spinopelvic Parameters

“Sagittal balance” is defined by the anatomic relationship between the pelvis and the spine in the sagittal plane to keep the center of gravity over the feet. It is important to calculate the anatomical parameters of cervical, thoracic, lumbar, and spinopelvic regions and how any static and dynamic changes could affect the sagittal balance to understand the conditions necessary for such a balance. One of the effective changes in sagittal balance is aging, which leads to changes in spine parameters and further activation of compensatory mechanisms. Understanding the relationships between these parameters, especially in pathological cases, helps correct spine sagittal imbalance

KIR Variation in Iranians Combines High Haplotype and Allotype Diversity With an Abundance of Functional Inhibitory Receptors.

Natural killer (NK) cells are innate lymphocytes that eliminate infected and transformed cells. They discriminate healthy from diseased tissue through killer cell Ig-like receptor (KIR) recognition of HLA class I ligands. Directly impacting NK cell function, KIR polymorphism associates with infection control and multiple autoimmune and pregnancy syndromes. Here we analyze KIR diversity of 241 individuals from five groups of Iranians. These five populations represent Baloch, Kurd, and Lur, together comprising 15% of the ethnically diverse Iranian population. We identified 159 KIR alleles, including 11 not previously characterized. We also identified 170 centromeric and 94 telomeric haplotypes, and 15 different KIR haplotypes carrying either a deletion or duplication encompassing one or more complete KIR genes. As expected, comparing our data with those representing major worldwide populations revealed the greatest similarity between Iranians and Europeans. Despite this similarity we observed higher frequencies of KIR3DL1*001 in Iran than any other population, and the highest frequency of HLA-B*51, a Bw4-containing allotype that acts as a strong educator of KIR3DL1*001+ NK cells. Compared to Europeans, the Iranians we studied also have a reduced frequency of 3DL1*004, which encodes an allotype that is not expressed at the NK cell surface. Concurrent with the resulting high frequency of strong viable interactions between inhibitory KIR and polymorphic HLA class I, the majority of KIR-A haplotypes characterized do not express a functional activating receptor. By contrast, the most frequent KIR-B haplotype in Iran expresses only one functional inhibitory KIR and the maximum number of activating KIR. This first complete, high-resolution, characterization of the KIR locus of Iranians will form a valuable reference for future clinical and population studies