51 research outputs found

    Constraining the anisotropic expansion of the universe with type ia supernovae and improving the treatment of selection effects within bayesian hierarchical models

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    In thesis, I aim to apply advanced methods in Bayesian statistical modelling on Type Ia Supernovae (SNIa) data to determine tighter constraints on the fiducial Lambda-Cold-Dark-Matter (LCDM) cosmology and improve the modelling of systematic uncertainties in the data. The body of work covered herein can be broadly classified into two main topics: I re-examine the contentious question of constraints on anisotropic expansion from SNIa in the light of a novel determination of peculiar velocities, which are crucial to test isotropy with SNe, out to distances < 200/h Mpc.The Bayesian hierarchical model BAHAMAS is adopted to constrain a dipole in the distance modulus in the context of the LCDM model and the deceleration parameter in a phenomenological Cosmographic expansion. I find no evidence for anisotropic expansion, and place a tight upper bound on the amplitude of a dipole, in a LCDM setting, and the Cosmographic expansion approach. Using Bayesian model comparison, I obtain posterior odds in excess of 900:1 (640:1) against a constant-in-redshift dipole for LCDM (Cosmographic expansion). One of the modern problems of Supernovae cosmology is accounting for selection effects caused by Malmquist bias in a principled way. Here, I present a complete formalism for handling selection effects in Type Ia supernova (SNIa) cosmology in the context of Bayesian Hierarchical Modeling. I demonstrate the method on simulated data sets where selection cuts are made on the apparent magnitude and show that previous results by Rubin et al, (2015) are incorrect and can lead to biased cosmological parameters reconstruction. I how this formalism is easily extended to include the Phillips corrections that are used to standardize SNe. The formalism presented exhibits better statistical properties in terms of bias and mean squared error relative to a traditional ad hoc style correction and the model of Rubin et al, (2015)Open Acces

    Law and Modern Technology: Lack of Tech Knowledge in Legal Profession May Cause Injustice

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    There is no such field where technology hasn’t reached. It will be a dream to think something without technology. In today’s world every field requires tech knowledge. The courtroom and law offices have changed with the evolution of technology. Most courts don’t accept paper files anymore. Law offices use virtual file to store client information. However, due to old age or other reason a significant number of attorneys and judges are not competent in technology. This paper will examine the use of technology in our legal system and what problem arises due to lack of proper tech knowledge. Increasing use of computer and internet in the courtroom and law office, trial presentation, keeping client’s confidential data secure, legal researching, e-filing document with the court require tech knowledge. This paper will discuss the necessity of tech knowledge, ethical obligation, expert’s opinions and case laws to demonstrate that to practice laws nowadays requires tech knowledge. After examining all relevant materials, this paper has revealed that to comply with the digital world all legal professionals should have enough tech knowledge for better litigation and avoid errors in the litigation

    Forensic Science: Complex Admissibility Standard for Scientific Evidence and Expert Witness\u27s Testimony

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    Modern science forces the world to accept new theories and invention. Science has invented several tools, which are used in the legal system to dispute criminal cases. Scientific evidence and expert witness testimony have weight in the courtroom because those are scientifically proved to be true. Even though there are few case laws and Federal rule of evidence 1975, still the admissibility standard is complex which may lead injustice. This article examines the Federal rule of evidence, case laws and scholars’ opinion to address the complexity of the admissibility standard of scientific evidence and expert testimony. The first legal question raised relating the admissibility standard was Frye v. United States (1923) where the court ruled that any scientific method or practice must be generally accepted by the scientific community at large. The First Federal rule of evidence was adopted in 1975. In 1980`s scientific scholars began to questioning the authenticity of the admitted scientific evidence saying the kind of expertise regularly accepted as admissible by courts was, frankly, \u27junk\u27 of scandalous lack of dependability. \u27 To address the problem of junk science in the courtroom, the United States Supreme Court decided Daubert v. Merrell Dow Pharma, Inc. (1993) In this case the Court addressed a new standard for determining the admissibility of scientific evidence in the federal courts of the U.S. After examining the case laws and statues, it revealed US has legal system has complex admissibility standard for scientific evidence and expert witness interpreted by the judges and may serve injustice to innocent people

    INFORMAL SUPPORT SYSTEM AND OTHER PSYCHOSOCIAL FACTORS IN THE USE OF ALCOHOL BY YOUTH.

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    A 180-item questionnaire of drinking characteristics was developed and administered to 539 university students. The survey instrument asked about alcohol consumption, drinking context, and a variety of potential predictor variables, including background factors, family domain, peer support, personality and attitudes, and reasons for drinking. Thirty scales were developed. The dependent measures of drinking included questions on frequency, quantity, number of alcohol related problems and two comparative questions, namely, drinking as compared to social acquaintances and close friends. The demographic characteristics most associated with drinking included gender (male), race (white), living arrangements (living in dorms) and academic performance (lower grades). A strong association was found between the use of marijuana and different measures of drinking, particularly the number of alcohol related problems. In the family domain, the best predictors of four of the drinking measures were permissive attitudes of parents, and reports of parental alcohol and other emotional problems. The quality of the relationship with parents was not found to predict alcohol abuse, and neither was the marital status of parents. The friendship scales tapping perceived support were not found to contribute as much as other domains, though the number of alcohol related problems was negatively associated with identity confirmation, emotional support, and empathy. In the personality domain, the best predictor of all the dependent measures was need for play. Such variables as self concept were not found to be useful. The domains of attitudes toward alcohol and reasons for drinking were the best predictors, accounting for more than half the variance. A permissive attitude toward the use of alcohol was associated with heavier consumption. Drinking to get drunk, as a reason for drinking, was the best predictor of drinking. The relative contribution of the different predictors appears to depend on whether one is concerned with differentiating extremes and across different levels, or adjacent levels, such as abstainers versus moderate drinkers.Dept. of Psychology. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1987 .R345. Source: Dissertation Abstracts International, Volume: 48-07, Section: B, page: 2144. Thesis (Ph.D.)--University of Windsor (Canada), 1987

    An Enhanced Zero Crossing Based HVAC Phase Synchronous Inverter for Electrostatic Generator in Microgrid Systems

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    Electrostatic Generator (ESG) faced far more challenges when it integrated with the phase synchronous inverter systems as ESG can generate high voltage DC and very low current. This high DC voltage needs to be converted and also low current of the ESG have to be increased for microgrid system which works generally performed by power inverter circuit. Therefore, phase synchronous inverter (PSI) is presented, to increase the inverter output current, with the aid of zero crossing voltage source controller. However, there is an issue to design the inverter which are harmonic distortion and phase angle. In this paper, a zero-crossing circuit is developed to synchronize inverter and microgrid phase and according to the simulation result, the phase angle is 3.22°. In addition, an LCL filter is designed to reduce the harmonic distortion. The performance of the PSI had been demonstrated by modeling it in MATLAB2016a software. The considered parameter of the design is input voltage 10kV, switching frequency 60Hz, modulation index 0.85 and cut-off frequency 33Hz. The simulation results show that the designed inverter can greatly improve the system stability and robustness of the microgrid system and the obtained PSI system efficiency is 97.35% that performed better compared to the related inverter techniques

    Manifesting a mobile application on safety which ascertains women salus in Bangladesh

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    This paper reflects on the indemnity of women in our society. The proposed model ensures the embodiment of a mobile application. The algorithm, we developed for this model focuses the safety issues which is applicable to both inside as well as outside of the house for the women in Bangladesh. The solution of this problems can be done through some interrelated features such as i) SOS button pressing which ensures automatic calling, instant location tracking system through GPS of the phone and sending tracked location to all trusted numbers, automatically secrete video recording system ii) voice command detection which assures exact same features as SOS button pressing iii) phone shaking features serve user instant immunity by calling a trusted number. This research also assures experimented data analysis at Dhaka city based on respond time, the time it takes to arrive the SMS and Phone call and current location of the victim. Also do a short comparison among the most popular safety related mobile applications

    Experimental Validation of Microwave Tomographywith the DBIM-TwIST Algorithm for Brain StrokeDetection and Classification

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    We present an initial experimental validation of a microwave tomography (MWT) prototype for brain stroke detection and classification using the distorted Born iterative method, two-step iterative shrinkage thresholding (DBIM-TwIST) algorithm. The validation study consists of first preparing and characterizing gel phantoms which mimic the structure and the dielectric properties of a simplified brain model with a haemorrhagic or ischemic stroke target. Then, we measure the S-parameters of the phantoms in our experimental prototype and process the scattered signals from 0.5 to 2.5 GHz using the DBIM-TwIST algorithm to estimate the dielectric properties of the reconstruction domain. Ourresultsdemonstratethatweareabletodetectthestroketargetinscenarios where the initial guess of the inverse problem is only an approximation of the true experimental phantom. Moreover, the prototype can differentiate between haemorrhagic and ischemic strokes based on the estimation of their dielectric properties
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