Lorentz-Violating Vector Fields Slow the Universe Down

We consider the gravitational effects of a single, fixed-norm, Lorentz-violating timelike vector field. In a cosmological background, such a vector field acts to rescale the effective value of Newton's constant. The energy density of this vector field precisely tracks the energy density of the rest of the universe, but with the opposite sign, so that the universe experiences a slower rate of expansion for a given matter content. This vector field similarly rescales Newton's constant in the Newtonian limit, although by a different factor. We put constraints on the parameters of the theory using the predictions of primordial nucleosynthesis, demonstrating that the norm of the vector field should be less than the Planck scale by an order of magnitude or more.Comment: 15 pages, Revtex4, updated version. Added References. Minor Typos corrected. Older version published in PR

Spectroscopic infrared extinction mapping as a probe of grain growth in IRDCs

We present spectroscopic tests of MIR to FIR extinction laws in IRDC G028.36+00.07, a potential site of massive star and star cluster formation. Lim & Tan (2014) developed methods of FIR extinction mapping of this source using ${\it Spitzer}$-MIPS ${\rm 24\mu m}$ and ${\it Herschel}$-PACS ${\rm 70\mu m}$ images, and by comparing to MIR ${\it Spitzer}$-IRAC $3$--${\rm 8\mu m}$ extinction maps, found tentative evidence for grain growth in the highest mass surface density regions. Here we present results of spectroscopic infrared extinction (SIREX) mapping using ${\it Spitzer}$-IRS (14 to ${\rm 38\mu m}$) data of the same IRDC. These methods allow us to first measure the SED of the diffuse Galactic ISM that is in the foreground of the IRDC. We then carry out our primary investigation of measuring the MIR to FIR opacity law and searching for potential variations as a function of mass surface density within the IRDC. We find relatively flat, featureless MIR-FIR opacity laws that lack the $\sim{\rm 12\mu m}$ and $\sim{\rm 35\mu m}$ features associated with the thick water ice mantle models of Ossenkopf & Henning (1994). Their thin ice mantle models and the coagulating aggregate dust models of Ormel et al. (2011) are a generally better match to the observed opacity laws. We also find evidence for generally flatter MIR to FIR extinction laws as mass surface density increases, strengthening the evidence for grain and ice mantle growth in higher density regions.Comment: 12 pages, 12 Figures, 1 Table, Accepted to be published to Ap

Analysis of Flavonoids and Essential Oils from Clausena Excavata and Their Medicinal Properties

This study was conducted mainly to determine the major flavonoid compounds and the composition of essential oils predominant in Clausena excavata, and also to examine its antioxidant, antibacterial and anticancer activities. The dried yields of C. excavata’s leaf crude extracts were also determined and methanol was found to be the best solvent for extracting soluble bioactive compounds from the leaves of C. excavata. Total phenolic contents were found abundantly in methanol crude extract of leaves. In the high performance liquid chromatography (HPLC) analysis, rutin and naringin were found predominant in the leaves of C. excavata, while in the gas chromatography-mass spectrometry (GC-MS) analysis, the major chemical components identified in the fruit oil were α-ocimene and terpinolene. Terpinolene was also being the main component and remarkably present in the leaf oil. Both of the fruit and leaf oils extracted with dichloromethane in the simultaneous distillation extraction (SDE) method were indicated in very low yield (less than 0.1%). Antioxidant activities of various crude extracts of Clausena excavata leaves were dependent on the amount of total phenolics present in the crude extracts. Inhibition of lipid peroxidation and free radical scavenger potential of those crude extracts closely dependent on the particular substitution pattern of free hydroxyl groups on the flavonoid skeleton. Antioxidant activity of methanol crude leaf’s extract was found greater than α-tocopherol in the ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods as well. The increase in the concentration of methanol crude leaf extract from 200 to 1000 μg/ml had increased its antioxidant activity. However, methanol crude leaf’s extract exhibited weak scavenging activity towards 1,1- diphenyl-2-picrylhydrazyl (DPPH) free radical. As for the determination of antibacterial activity in both of the disc diffusion and microdilution methods, the growth of all tested gram-positive bacteria, especially Micrococcus luteus was found effectively affected by the methanol crude leaf extract. Almost all of the crude extracts were active towards Micrococcus luteus. Fruit and leaf oil exhibited their effects on all tested gram-positive bacteria and certain gram-negative bacteria but those tested bacteria strains were just weakly inhibited. Antioxidant activity of flavonoids was associated with anticancer properties. In the MTT assay, however, fruit oil showed better cytotoxic activity than that in methanol crude leaf extract against MCF-7 cells. This implied that C. excavata fruit oil might be a good source for the breast cancer treatment due to the presence of possible active anticancer agents

Star Decompositions of Bipartite Graphs

In Chapter 1, we will introduce the definitions and the notations used throughout this thesis. We will also survey some prior research pertaining to graph decompositions, with special emphasis on star-decompositions and decompositions of bipartite graphs. Here we will also introduce some basic algorithms and lemmas that are used in this thesis. In Chapter 2, we will focus primarily on decomposition of complete bipartite graphs. We will also cover the necessary and sufficient conditions for the decomposition of complete bipartite graphs minus a 1-factor, also known as crown graphs and show that all complete bipartite graphs and crown graphs have a decomposition into stars when certain necessary conditions for the decomposition are met. This is an extension of the results given in "On claw-decomposition of complete graphs and complete bigraphs" by Yamamoto, et. al. We will propose a construction for the decomposition of the graphs. In Chapter 3, we focus on the decomposition of complete equipartite tripartite graphs. This result is similar to the results of "On Claw-decomposition of complete multipartite graphs" by Ushio and Yamamoto. Our proof is again by construction and we propose how it might extend to equipartite multipartite graphs. We will also discuss the 3-star decomposition of complete tripartite graphs. In Chapter 4 , we will discuss the star decomposition of 4-regular bipartite graphs, with particular emphasis on the decomposition of 4-regular bipartite graphs into 3-stars. We will propose methods to extend our strategies to model the problem as an optimization problem. We will also look into the probabilistic method discussed in "Tree decomposition of Graphs" by Yuster and how we might modify the results of this paper to star decompositions of bipartite graphs. In Chapter 5, we summarize the findings in this thesis, and discuss the future work and research in star decompositions of bipartite and multipartite graphs

Chameleon: a Blind Double Trapdoor Hash Function for Securing AMI Data Aggregation

Data aggregation is an integral part of Advanced Metering Infrastructure (AMI) deployment that is implemented by the concentrator. Data aggregation reduces the number of transmissions, thereby reducing communication costs and increasing the bandwidth utilization of AMI. However, the concentrator poses a great risk of being tampered with, leading to erroneous bills and possible consumer disputes. In this paper, we propose an end-to-end integrity protocol using elliptic curve based chameleon hashing to provide data integrity and authenticity. The concentrator generates and sends a chameleon hash value of the aggregated readings to the Meter Data Management System (MDMS) for verification, while the smart meter with the trapdoor key computes and sends a commitment value to the MDMS so that the resulting chameleon hash value calculated by the MDMS is equivalent to the previous hash value sent by the concentrator. By comparing the two hash values, the MDMS can validate the integrity and authenticity of the data sent by the concentrator. Compared with the discrete logarithm implementation, the ECC implementation reduces the computational cost of MDMS, concentrator and smart meter by approximately 36.8%, 80%, and 99% respectively. We also demonstrate the security soundness of our protocol through informal security analysis

Development of a Freight Demand Model with an Application to California

ABSTRACTThis paper discusses the disaggregation of the Federal Highway Administration's Freight Analysis Framework (FAF) database (version 3.0) on freight origin-destination data and the development of linear regression equations to describe the relationships between commodity-based freight trip productions/attractions to specific economic variables. Instead of generating a production/attraction equation for each commodity, commodities are grouped in certain ways to simplify model development and application. We consider three grouping methods and two model selection criteria (with and without intercepts), which are compared in terms of goodness of fit with two data sets (FAF versions 2.0 and 3.0). Furthermore, the freight generation models are validated using county-level economic data in California and applied to predict year 2015 commodity outputs. The results of this study can help city, county, metropolitan and state level planning agencies develop their own customized freight demand generation models without performing costly large-scale surveys

Is Australia Ready for Autonomous Vehicles? Examining the Factors Influencing AV Adoption through Expert Interviews

As Autonomous Vehicles (AVs) on public roads today becomes an increasingly realistic possibility, there is growing need to better understand the factors that will facilitate their successful introduction. This study focuses specifically on Australia and investigates various micro and macro environmental factors that may either hinder or support their adoption in the country. The study comprised 18 in-depth interviews with experts from both the public and private sectors who possess direct experience working with AVs. These experts provided valuable insights into several areas, including the legislation and regulations governing AV use, the technical and infrastructure requirements necessary for safe operation on public roads, and the importance of public sentiment in driving AV adoption and introduction. Based on the study’s findings, an integrated framework has been developed to identify and classify the key factors related to AV adoption, as well as their interrelatedness with each other. This framework seeks to guide the development of national strategies to accommodate the necessary political, legal, and social adjustments required for the successful implementation of AVs

Exploring the Relationship between Organizational Culture and Information Security Culture

Managing Information Security is becoming more challenging in today’s business because people are both a cause of information security incidents as well as a key part of the protection from them. As the impact of organizational culture (OC) on employees is significant, many researchers have called for the creation of information security culture (ISC) in organizations to influence the actions and behaviour of employees towards better organizational information security. Although researchers have called for the creation of ISC to be embedded in organizations, nonetheless, literature suggests that little past research examining the relationship between the nature of OC and ISC. This paper seeks to explore the relationship between the nature of OC and ISC and argues that organizations that have a medium to high security risk profile need to embed the ISC to influence employee actions and behaviours in relation to information security practices. In addition, this paper also introduces a framework to assist organizations in determining the extent to which the desired ISC is embedded into OC

Embedding Information Security Culture Emerging Concerns and Challenges

The behaviour of employees has been identified as a key factor in the protection of organizational information. As such, many researchers have called for information security culture (ISC) to be embedded into organizations to positively influence employee behaviour towards protecting organizational information. Despite claims that ISC may influence employee behaviours to protect organizational information, there is little empirical work that examines the embedding of ISC into organizations. This paper argues that embedding ISC should not only focus on employee behaviour, but rather in a holistic manner, involve everyone in the organization. The argument is developed through case studies in two organizations based on semi structured interviews of respondents, observations, and documents analysis from each organization. The results show that the challenges of embedding ISC are not as simple as changing employee behaviour and technical aspects of security. Rather, the more challenging problem is how to embed ISC in a holistic manner that includes senior management support and involvement to instil awareness through mandatory training with a clear assignment of responsibility and constant enforcement of security policies and procedures. We believe that the findings will provide researchers in ISC with a broader view of how ISC can be embedded in organizations