The Portevin-Le Chatelier effect in the Continuous Time Random Walk framework

We present a continuous time random walk model for the Portevin-Le Chatelier (PLC) effect. From our result it is shown that the dynamics of the PLC band can be explained in terms of the Levy Walk

Towards Logic Functions as the Device using Spin Wave Functions Nanofabric

As CMOS technology scaling is fast approaching its fundamental limits, several new nano-electronic devices have been proposed as possible alternatives to MOSFETs. Research on emerging devices mainly focusses on improving the intrinsic characteristics of these single devices keeping the overall integration approach fairly conventional. However, due to high logic complexity and wiring requirements, the overall system-level power, performance and area do not scale proportional to that of individual devices. Thereby, we propose a fundamental shift in mindset, to make the devices themselves more functional than simple switches. Our goal in this thesis is to develop a new nanoscale fabric paradigm that enables realization of arbitrary logic functions (with high fan-in/fan-out) more efficiently. We leverage on non-equilibrium spin wave physical phenomenon and wave interference to realize these elementary functions called Spin Wave Functions (SPWFs). In the proposed fabric, computation is based on the principle of wave superposition. Information is encoded both in the phase and amplitude of spin waves; thereby providing an opportunity for compressed data representation. Moreover, spin wave propagation does not involve any physical movement of charge particles. This provides a fundamental advantage over conventional charge based electronics and opens new horizons for novel nano-scale architectures. We show several variants of the SPWFs based on topology, signal weights, control inputs and wave frequencies. SPWF based designs of arithmetic circuits like adders and parallel counters are presented. Our efforts towards developing new architectures using SPWFs places strong emphasis on integrated fabric-circuit exploration methodology. With different topologies and circuit styles we have explored how capabilities at individual fabric components level can affect design and vice versa. Our estimates on benefits vs. 45nm CMOS implementation show that, for a 1-bit adder, up to 40x reduction in area and 228x reduction in power is possible. For the 2-bit adder, results show that up to 33x area reduction and 222x reduction in power may be possible. Building large scale SPWF-based systems, requires mechanisms for synchronization and data streaming. In this thesis, we present data streaming approaches based on Asynchronous SPWFs (A-SPWFs). As an example, a 32-bit Carry Completion Sensing Adder (CCSA) is shown based on the A-SPWF approach with preliminary power, performance and area evaluations

Investigation of DC magnetron-sputtered TiO2 coatings: Effect of coating thickness, structure, and morphology on photocatalytic activity

The photocatalytic performance of magnetron-sputtered titanium dioxide (TiO2) coatings of different thickness in anatase crystalline structure deposited on aluminium 1050 alloy substrates was investigated using a combination of photo-electrochemistry, methylene blue decomposition, and microscopic and spectroscopic methods, such as high resolution scanning and transmission electron microscopy, atomic force microscopy and ellipsometry. The reaction resistance was measured by AC impedance, while photocurrent measurements were carried out using the zero resistance ammetry (ZRA) method. The results showed that the TiO2 grains grow in dipyramidal columns having a linear increase in surface area with increased coating thickness. The refractive index values indicate also an evolutionary growth.The refractive index values obtained for the thin coatings on aluminium substrate were well below the values reported for monocrystalline anatase. The photocatalytic performance increased with increased coating thickness, though more rapidly over a range of 100 - 500 nm thickness. The dielectric constant also increased linearly with coating thickness.<br/

Microstructure and optical appearance of anodized friction stir processed Al - Metal oxide surface composites

Multiple-pass friction stir processing (FSP) was employed to impregnate Ti, Y and Ce oxide powders into the surface of an Aluminium alloy. The FSP processed surface composite was subsequently anodized with an aim to develop optical effects in the anodized layer owing to the presence of incorporated oxide particles which will influence the scattering of light. This paper presents the investigations on relation between microstructure of the FSP zone and optical appearance of the anodized layer due to incorporation of metal oxide particles and modification of the oxide particles due to the anodizing process. The effect of anodizing parameters on the optical appearance of the anodized surface was studied. Characterization was performed using SEM, FIB-SEM, TEM and GI-XRD. The surface appearance was analysed using photospectrometry technique which measures the diffuse and total reflectance of the surface. The appearance of the anodized surface changed from dark to bright upon increasing the anodizing voltage. Particles in the FSP zone were partially or completely modified during the anodizing process and modified the morphology of the surrounding anodized Al matrix which has a clear influence on the mechanism of light interaction like scattering and absorption from the anodized surface

Studies of concentration and temperature dependencies of precipitation kinetics in iron-copper alloys using kinetic monte carlo and stochastic statistical simulations

The earlier-developed ab initio model and the kinetic Monte Carlo method (KMCM) are used to simulate precipitation in a number of iron-copper alloys with different copper concentrations x and temperatures T. The same simulations are also made using the improved version of the earlier-suggested stochastic statistical method (SSM). The results obtained enable us to make a number of general conclusions about the dependencies of the decomposition kinetics in Fe-Cu alloys on x and T. We also show that the SSM describes the precipitation kinetics in a fair agreement with the KMCM, and employing the SSM in conjunction with the KMCM enables us to extend the KMC simulations to the longer evolution times. The results of simulations seem to agree with available experimental data for Fe-Cu alloys within statistical errors of simulations and the scatter of experimental results. Comparison of results of simulations to experiments for some multicomponent Fe-Cu-based alloys enables us to make certain conclusions about the influence of alloying elements in these alloys on the precipitation kinetics at different stages of evolution.Comment: 18 pages, 17 postscript figures, LaTe

Static Analysis of Data Transformations in Jupyter Notebooks

Jupyter notebooks used to pre-process and polish raw data for data science and machine learning processes are challenging to analyze. Their data-centric code manipulates dataframes through call to library functions with complex semantics, and the properties to track over it vary widely depending on the verification task. This paper presents a novel abstract domain that simplifies writing analyses for such programs, by extracting a unique CFG from the notebook that contains all transformations applied to the data. Several properties can then be determined by analyzing such CFG, that is simpler than the original Python code. We present a first use case that exploits our analysis to infer the required shape of the dataframes manipulated by the notebook

Epitaxial engineering of ferrimagnetic double perovskites

Double perovskite (DP) oxides of the type A2BB’O6 (A: 12-coordinated large di/tri-valent cation; B/B’: octahedrally coordinated transition metals) offer a unique material framework to engineer a wide range of physical functionalities. In its simplest form, the DP structure involves a cubic array of A-cations which is interspersed by corner-sharing BO6 and B’O6 octahedra, often arranged in a rock-salt type order. The choice of the B/B’ cations and their coupling within the ordered DP structure are known to largely determine the electronic structure and the resulting functionality of the compounds. Compounds such as the 3d5-4d1 coupled Sr2FeMoO6 (which exhibits fully spin polarized charge carriers and large magnetoresistance at room-temperature) and the 3d3-5d3 coupled Sr2CrOsO6 (which shows a high ferrimagnetic ordering temperature and a positive temperature coefficient of coercivity) stand as prominent examples for the diversity of physical functionalities achievable in these compounds. Yet, it is interesting to note that a vast majority of all possible DP compounds remain experimentally unexplored, mainly due to the meta-stable nature of some compounds and/or due to challenging synthesis procedures. With recent advances in thin film technology, particularly with techniques such as pulsed laser deposition (PLD), the ability to stabilize complex multi-cation oxides by epitaxial strain under non-equilibrium growth conditions has been well established. Furthermore, the PLD process has also been noted to support spontaneous cation ordering driven by a contrast in size/charge of cations. These developments provide an effective alternative route to overcome the synthesis challenges associated with meta-stable DP compounds. In this work, we use the PLD based thin film approach to explore ferrimagnetic insulating phases among DPs. Such phases when stabilized as thin films can have wide range of possible device applications in the areas of spin-electronics and modern computing. In addition, such compounds can also be viable templates for achieving single phase type I multiferroism, if the A-sites are subsequently substituted with a ferroelectric active cation such as Bi3+. The study was carried out across two families of double perovskites, namely 3d-3d and 3d-5d (the nomenclature refers to the elemental periods from which the B and B’ cations are chosen). Within the 3d-3d family, we chose to explore Bi2FeCrO6 (BFCO), a compound theoretically predicted to be a robust ferrimagnetic-ferroelectric. Epitaxial thin films of BFCO grown via PLD on single crystal SrTiO3 (STO) substrates were phase pure and fully strained. Distinct and intense superstructure peaks (SPs) were observed in XRD scans along the pseudo-cubic [111] direction. Considering the low scattering contrast between Fe and Cr, intensity of the SPs appeared suspiciously high. Using the photon energy dependence of contrast between atomic scattering factors of Fe and Cr, a spontaneous chemical ordering at the B-site was ruled out. Detailed structural calculations showed that the experimentally observed superstructure occurs due to crystal distortions involving unequal shifts of cations along the pseudo-cubic [111] direction. This result helped to clarify the discrepancies in magnetic and structural order reported for BFCO. It was also established that the observation of the XRD SPs alone may not be sufficient proof of chemical ordering in DPs. Consequently a very weak magnetization of 0.06 µB/f.u. was achieved for BFCO. The key findings from BFCO paved way for further work on 3d-5d family of DPs which, owing to larger possible B/B’ cation size/charge contrasts, offer better prospect of achieving structural and magnetic order. However 3d-5d compounds for insulating magnetism or multiferroic purposes have so far been neglected due to rarity of insulating phases among them as well as complicated synthesis involved. Using density functional calculations, new ferrimagnetic insulating phases were identified in two promising DPs La2MnReO6 (LMRO) and La2NiReO6 (LNRO). Motivated by the findings, stoichiometric ceramic pellets for PLD growth of LMRO and LNRO were fabricated via an evacuated sealed quartz tube sintering process. Subsequently, established PLD procedures were used to epitaxially stabilize phase pure films of LMRO and LNRO on single crystalline STO substrates. In contrast to BFCO, both 3d-5d compounds showed a theoretically consistent and significant magnetization of 2.20 (LMRO) and 0.38 (LNRO) µB/f.u. suggesting presence of a stable magnetic and chemical order. A cross-sectional atomic resolution transmission electron microscopy and energy dispersive X-ray analysis confirmed the B/B’ chemical order in LMRO. X-ray magnetic circular dichroism measurements showed consistent observation in accordance with the ferrimagnetic order and also provided evidence of an unquenched orbital moment. Furthermore, a metal to insulator transition observed in LMRO added to the functional qualities of the compound. This transition was noted to result from an orbital symmetry selective hybridization of 3d and 5d orbitals and the same was confirmed by dynamic mean field theory calculations. The results illustrate the untapped potential of double perovskites as functional oxides and the effectiveness of the PLD based thin film approach to realize them

Cultivating Compassion: A Cross-Sectional Evaluation of Empathy Among Medical Undergraduate Students

ABSTRACT: BACKGROUND: Empathy plays a crucial role in medical practice, profoundly affecting patient outcomes and treatment. Understanding the factors that influence empathy among medical students can help in developing strategies to enhance empathetic skills during medical training. This study aims to evaluate the correlates of empathy among medical undergraduate students using an epidemiological cross-sectional design. MATERIALS AND METHODS: A cross-sectional study was conducted among 270 medical undergraduate students from various academic years at JSS Medical College for four months (September 2023-December 2023). Convenient sampling was used to select study participants. Participants completed a standardized empathy questionnaire, the Jefferson Scale of Empathy Student Version (JSE-S) and a demographic survey. Statistical tests like Chi-square tests and Pearson’s correlation test were used. RESULTS: Among 270 students who participated in the study, 145(54%) were females and 125(46%) were males. The mean age of students was 22 + 1.8 years. The mean empathy score among males (79.72 + 9.83) and females (79.49 + 10.36). A correlation was made between the study participants\u27 Age and Total Empathy Score which showed a statistically significant positive correlation (r= 0.265). CONCLUSION: This study highlights key correlates of empathy among medical undergraduate students. The similar empathy scores across genders highlight that both male and female students possess comparable levels of empathy. The increase in age among medical students influences empathy development which encourages the cultivation of empathetic healthcare professionals. Keywords: Correlates of Empathy, Clinical Exposure, Empathy, Medical Education, Undergraduate student

Magnetic Resonance Cholangiopancreatography in 3 Tesla: 2D MRCP versus 3D MRCP in Diagnostic Evaluation with Special Reference to Different Acquisition and Reconstruction Planes

Purpose: Magnetic resonance cholangiopancreatography (MRCP) is an established technique for the evaluation of intra- and extrahepatic bile ducts in patients with known or suspected hepatobiliary disease. However, the ideal acquisition and reconstruction plane for optimal bile duct evaluation with 3D technique has not been evaluated.The purpose of our study was to compare different acquisition and reconstruction planes of 3D MRCP for bile duct assessment. Methods: 51 consecutive adult patients suspected to have pancreatico-biliary disease were examined with 3 Tesla (Philips 3 T Ingenia) system both a multi thin slice (3D) and a breath-hold (Single Shot) MRCP technique were performed. In the multi thin slice technique both source images and maximum intensity projections were examined. Two radiologists blinded to clinical information viewed both MRCP techniques independantly. Measure of correlation between each of the techniques and the inter observer agreement were computed. Coronal and axial MIP were reconstructed based on each dataset (resulting in two coronal and two axial MIP, respectively) and assessed the MIP, regarding visualization of bile ducts and image quality.Results were compared (Wilcoxon test). Intra- and interobserver variability were calculated (kappa-statistic). Results: In case of coronal data acquisition, visualization of bile duct segments was significantly better on coronal reconstructed MIP images as compared to axial reconstructed MIP (p \u3c 0.05). Regarding visualization, coronal MIP of the coronal acquisition were equal to coronal MIP of the axial acquisition (p \u3e 0.05). Image quality of coronal and axial datasets did not differ significantly. Obstruction due to tumor was shown in 30% of patients, and calculi in the common bile duct were shown also in 30% of patients employing the 3D MRCP technique. Obstruction due to tumor and calculi were shown in 30% and 21% of patients, respectively, using the SS 2D MRCP technique. Sensitivity and specificity in distinguishing calculi in the common bile duct by 3D MRCP and SS MRCP were 100%, 100%, 70% and 100% respectively. Conclusions: Although the 3D MRCP multislice technique is more time consuming than the SS MRCP breath-hold technique at a 3 Tesla (Philips 3 T Ingenia) system it is advisable to use thin slice 3D MRCP in order not to misdiagnose calculi in the common bile duct.The results of our study suggest that for visualization and evaluation of intra- and extrahepatic bile duct segments reconstructed images in coronal orientation are preferable

Association of Physical Activity and Screen Time Usage of Adolescents in Rural Areas of Mysore.

Introduction: In these changing times there have been increased usage of screen device due to more accessibility to both device and the internet and a greater number of children are having reduced physical activity. The purpose of the current study was to determine if screen usage among adolescents (11-17yrs) who live in supportive environments is associated with decreased levels of moderate to vigorous physical activity. Methods & materials: A school-based cross-sectional study was conducted in two rural schools of Mysore, Karnataka in February 2023, in 176 students between the age group of 11 – 17yrs. Physical activity and screen time was evaluated using a questionnaire. School sports, Leisure Time Physical Activity (LTPA), and mode of transportation to school was evaluated for their physical activity pattern and the amount of time spent on each type of screen device – TV, Computers, video games, mobile phones, and tablets was measured in hours per day. Results: Prevalence of excessive screen time usage was 36%and physical activity \u3e1hr./day was found to be 57% in study subjects. However, there is no correlation between physical exercise and screen time found in rural adolescents. Conclusion: Prevalence of excessive screen time with 57% of adolescents having physical activity more than 1hr/day. A tighter control of screen usage was also shown by 77% of adolescents, being role models for appropriate screen time, all are factors for an improved lifestyle