Finite element analysis of a projectile during gun launch

The air gun test is a possible way to study the transient shock environment that a projectile is anticipated to encounter in an actual field test. The air gun test simulates the real gun test in a controlled environment by firing the projectile into an energy absorbing material like aluminum honeycomb. This thesis presents the use of Lagrangian and Arbitrary Lagrangian and Eulerian method in simulating the gun launch dynamics of a generic artillery component subjected to launch simulation in an air gun test. The aluminum honeycomb absorbs the kinetic energy of a projectile by deforming plastically. There are many material models for simulating aluminum honeycomb material in LS-DYNA. The MAT_CRUSHABLE_FOAM and MAT_MODIFIED_CRUSHABLE_FOAM material models are used for simulating the aluminum honeycomb. Four strike face geometry for aluminum honeycomb mitigator is studied - flat, double wedge, single wedge, and pyramid shape. The critical factors such as yield strength of the honeycomb and mass of momentum exchange mass (MEM - secondary energy absorbing device), which affect the dynamic response of projectile are studied. The acceleration, velocity and displacement of the projectile are compared to experiment results

Anti-anxiety activity of ethanolic extract of Spermacoce hispida leaves in swiss albino mice

Background: The objective of the study was to evaluate the anxiolytic activity of ethanolic extract of Spermacoce hispida (EESH) in swiss albino mice.Methods: Forty eight adult Swiss albino mice weighing 25-30grams were selected. 24 were allocated to Elevated plus maize test and the remaining 24 to Bright and dark box test models. In each model, there were 4 groups. The control group received normal saline (10ml/kg), the standard, Diazepam (1mg/kg) and test groups received ethanolic extract of Spermacoce hispida (100mg/kg, 200mg/kg p.o. respectively) 1h prior to the acute study. In chronic study the drugs were given orally once a day for 10 days and the last dose was given 1h before the experiment. The antianxiety activity of the test drug was evaluated using EPM test and Bright and dark box test experimental models of anxiety. All results were expressed as mean±standard error mean (SEM) and analysed by one-way ANOVA. Post-hoc comparisons were performed by applying Dunnet’s test. P <0.05 was considered statistically significant.Results: Ethanolic extract of Spermacoce hispida significantly increased the duration of time spent and number of entries in open arm in EPM and increased the number of entries into the bright arena, the time spent and the rears in bright arena indicating anxiolytic activity and EESH 200 mg/kg was found to be better than diazepam.Conclusions: The results of the present study suggest that the ethanolic extract of Spermacoce hispida have anxiolytic activity better than Diazepam

Impact of Stricter Content Moderation on Parler's Users' Discourse

Social media platforms employ various content moderation techniques to remove harmful, offensive, and hate speech content. The moderation level varies across platforms; even over time, it can evolve in a platform. For example, Parler, a fringe social media platform popular among conservative users, was known to have the least restrictive moderation policies, claiming to have open discussion spaces for their users. However, after linking the 2021 US Capitol Riots and the activity of some groups on Parler, such as QAnon and Proud Boys, on January 12, 2021, Parler was removed from the Apple and Google App Store and suspended from Amazon Cloud hosting service. Parler would have to modify their moderation policies to return to these online stores. After a month of downtime, Parler was back online with a new set of user guidelines, which reflected stricter content moderation, especially regarding the \emph{hate speech} policy. In this paper, we studied the moderation changes performed by Parler and their effect on the toxicity of its content. We collected a large longitudinal Parler dataset with 17M parleys from 432K active users from February 2021 to January 2022, after its return to the Internet and App Store. To the best of our knowledge, this is the first study investigating the effectiveness of content moderation techniques using data-driven approaches and also the first Parler dataset after its brief hiatus. Our quasi-experimental time series analysis indicates that after the change in Parler's moderation, the severe forms of toxicity (above a threshold of 0.5) immediately decreased and sustained. In contrast, the trend did not change for less severe threats and insults (a threshold between 0.5 - 0.7). Finally, we found an increase in the factuality of the news sites being shared, as well as a decrease in the number of conspiracy or pseudoscience sources being shared

Experimental and Finite Element Analysis of Preloaded Bolted Joints Under Impact Loading

One of the primary parameters in analyzing bolted joints is preload in the bolt. We have considered several possible preload modeling techniques to analyze the effect of preload on the dynamic response of the bolted joints. Five different methods of applying preload in the nonlinear finite element analysis are evaluated. These methods are “force on bolt and nut”, “force on bolt shank”, “interference fit”, “thermal gradient” and “initial stress method”. Explicit and implicit analyses are used for transient response and preload generation in bolt respectively. Time history and shock response spectrum are used to compare experimental and simulation results. Simulation results compared fairly well with the experimental results

PHYSICO-CHEMICAL CHARACTERIZATION OF SIDDHA SASTRIC FORMULATION ARUMUGA CHENDHURAM

Arumuga Chendhuram is a herbo-mineral formulation cited in Siddha Vaidya Thirattu prepared through the special oxidation procedure involving purified form of minerals processed under herbal juice. It has been practiced frequently for treating inflammation of joints and anorectal disorders at 65-130 mg with the adjuvant Honey. The present study dealt with analyzing the physico-chemical characterization of Arumuga Chendhuram to establish standard quality parameters. Two samples of Arumuga Chendhuram (Self prepared and Pharmacy Samples) were subjected to analytical tests and quantitative analyzes using Sophisticated Instruments. Analytical analysis showed low level of moisture content and extractive values in both samples but ash values were high. The functional groups analyzed by FT-Raman Spectroscopic study inferred different numbers of peaks among the samples. The particles of both samples were in 1-10 micron size scanned under Electron microscope. Elements found in both samples were in its oxide form at different concentrations which was analyzed through Wavelength dispersive X-Ray Fluorescence. Both samples contain high concentration of ferric oxide. The concentration of trace and heavy metals were analyzed using Inductively Coupled Plasma - Optical Emission Spectrometer showed the presence of low concentration of Mercury, Arsenic and Iron in self prepared Arumuga Chendhuram. From the result of above studies, we inferred that Arumuga Chendhuram prepared by us was superior to Pharmacy product in quality and that physicochemical fingerprint shall be used as standard

Experimental and numerical analysis of structures with bolted joints subjected to impact load

The aim of this study is to analyze the transient behavior of structures with bolted joints subjected to impact or shock loads using experimental methods and Finite Element Analysis (FEA). Various factors that affect the response of the bolted joint structures for shock loading were studied, such as damping, preload, intensity of impact load and type of FE modeling. The objective of this work was to develop computational modeling procedures that provide structural analysts an improved physics-based shock model for combat vehicles focusing mainly on shock transmission across bolted joints. There is only a limited amount of published literature describing the proper method for analyzing the transient shock propagation across bolted connections for high impact loading. The initial case study focused on a simple cantilever beam with bolted lap joint subjected to relatively low levels of impact force. The second case study used a flat plate bolted to a hat-section and the third structure evaluated was two hat sections bolted together. These simple configurations are representative of structures found in many military ground vehicles that can be subjected to transient impact and blast loads. These structures were subjected to low impact loading (non destructive) using impact hammers and high impact loading (destructive) using an air gun and their responses were measured using accelerometers. LS-DYNA FE solver was used to simulate the shock propagation in bolted structures. For all the bolted structures, the modal analysis was performed both experimentally and numerically. The results were in excellent agreement for lower modes and small deviation in higher modes. Secondly, the time history response of experimental and FE analysis are compared. Normalized Root Mean Square Deviation (NRMSD) criterion was used to compare the experimental and FE result. A full detailed FE model and a simplified FE model of the bolted structures were developed for impact analysis and their prediction were compared with the experimental results. In all the cases, the detailed FE model with 3-D solid elements showed good agreement with the experimental results. The simplified FE model with shell elements (bolts were not modeled) predicted higher magnitudes in the acceleration values. Addition of damping in the simplified FE model reduced the higher magnitudes in the predicted response and the results were in good agreement with the experiment. The simplified FE model developed for bolted joint structure in this report reduced the CPU time by one order (30 hours to 3.5 hours) and can be practically implemented in the full vehicle FE model for crash or blast analysis

In Vivo Assessment of Osseous Wound Healing Using Bone Putty in the Surgical Management of Tooth Extraction

Purpose: The objective of this pilot study was to evaluate the healing responses of a anesthetic bone putty in tooth extraction sockets of a canine model. Materials and Methods: In five beagle dogs the right mandibular premolars were extracted. The extraction sockets were grafted with one of the four treatment arms: 1) bone putty alone, 2) bone putty mixed with xenograft particulate bone (3:1), 3) xenograft sandwiched between bone putty and 4) xenograft covered with a collagen sponge. After 6 weeks, the healing extraction sockets were evaluated by microCT and histological analysis. Results: All sockets healed without complications. By microCT analysis, sockets grafted demonstrated comparable radiographic evidence of bone healing compared to control sockets. Histologically, a minimal inflammatory infiltrate was present in all the sockets. Conclusions: Our pre-clinical results indicate that this bone putty is a safe, biocompatible device that may be useful in the post-operative management of tooth extractions

Studies on length-weight relationship of Gerres filamentosus Cuvier from the estuaries of the southern Karnataka coast

Random samples of Gerres filamentosus Cuvier from the Netravathi-Gurpur, Mulky, Kallayanapura, Mabukala and Kundapura estuaries of the southern Karnataka Coast were collected in the years 2000, 2001 and 2002, and length-weight relationships for each estuary were derived using multiple linear regression technique with one dummy variable. Hence, combined or sex-wise length-weight relationships were obtained after testing for homogeneity and isometric growth condition of fishes for each estuary by t-test. The extent of closeness of length-weight relationships between sexes and among estuaries for different years is explained by a trend line graph. The whole process of multiple linear regression analysis with one dummy variable is a better substitute for the analysis of covariance technique

SoK: Content Moderation in Social Media, from Guidelines to Enforcement, and Research to Practice

To counter online abuse and misinformation, social media platforms have been establishing content moderation guidelines and employing various moderation policies. The goal of this paper is to study these community guidelines and moderation practices, as well as the relevant research publications to identify the research gaps, differences in moderation techniques, and challenges that should be tackled by the social media platforms and the research community at large. In this regard, we study and analyze in the US jurisdiction the fourteen most popular social media content moderation guidelines and practices, and consolidate them. We then introduce three taxonomies drawn from this analysis as well as covering over one hundred interdisciplinary research papers about moderation strategies. We identified the differences between the content moderation employed in mainstream social media platforms compared to fringe platforms. We also highlight the implications of Section 230, the need for transparency and opacity in content moderation, why platforms should shift from a one-size-fits-all model to a more inclusive model, and lastly, we highlight why there is a need for a collaborative human-AI system

Chandipura virus: a major cause of acute encephalitis in children in North Telangana, Andhra Pradesh, India

A hospital-based surveillance was undertaken between May 2005 and April 2006 to elucidate the contribution of Chandipura virus (CHPV) to acute viral encephalitis cases in children, seroconversion in recovered cases and to compare the seroprevalences of anti-CHPV IgM and N antibodies in areas reporting cases with those without any case of acute viral encephalitis. During this period, 90 cases of acute encephalitis were hospitalized in the pediatric wards of Mahatma Gandhi Memorial (MGM) Hospital, Warangal. There were 49 deaths (Case Fatality Rate, i.e., CFR of 54.4%). Clinical samples and records were obtained from 52 suspected cases. The cases were below 15 years, majority in 0-4 years (35/52, 67.3%). Computerized tomography (CT) scans and cerebro-spinal fluid (CSF) picture favored viral etiology. No neurological sequelae were observed. CHPV etiology was detected in 25 cases (48.1%, n = 52; RNA in 20, IgM in 3 and N antibody seroconversion in 2). JEV etiology was detected in 5 cases (IgM in 4 cases and seroconversion in 1 case). Anti-CHPV IgM seroprevalence in contacts (26/167, 15.6%) was significantly higher (P &lt; 0.05) than in non-contacts (11/430, 2.6%); which was also observed in children &lt; 15 years (19/90, 21.1% vs. 3/109, 2.7%). Anti-CHPV N antibody seroprevalence in &lt;15 years contacts (66/90, 73.3%) and non-contacts (77/109, 70.6%) was significantly lower (P &lt; 0.05) than in contacts (75/77, 97.4%) and non-contacts (302/321, 94.1%) more than 15 years respectively. CHPV appears to be the major cause of acute viral encephalitis in children in endemic areas during early monsoon months