Bridging the Gap Between Intent and Outcome: Knowledge, Tools & Principles for Security-Minded Decision-Making

Well-intentioned decisions---even ones intended to improve aggregate security--- may inadvertently jeopardize security objectives. Adopting a stringent password composition policy ostensibly yields high-entropy passwords; however, such policies often drive users to reuse or write down passwords. Replacing URLs in emails with safe URLs that navigate through a gatekeeper service that vets them before granting user access may reduce user exposure to malware; however, it may backfire by reducing the user\u27s ability to parse the URL or by giving the user a false sense of security if user expectations misalign with the security checks delivered by the vetting process. A short timeout threshold may ensure the user is promptly logged out when the system detects they are away; however, if an infuriated user copes by inserting a USB stick in their computer to emulate mouse movements, then not only will the detection mechanism fail but the insertion of the USB stick may present a new attack surface. These examples highlight the disconnect between decision-maker intentions and decision outcomes. Our focus is on bridging this gap. This thesis explores six projects bound together by the core objective of empowering people to make decisions that achieve their security and privacy objectives. First, we use grounded theory to examine Amazon reviews of password logbooks and to obtain valuable insights into users\u27 password management beliefs, motivations, and behaviors. Second, we present a discrete-event simulation we built to assess the efficacy of password policies. Third, we explore the idea of supplementing language-theoretic security with human-computability boundaries. Fourth, we conduct an eye-tracking study to understand users\u27 visual processes while parsing and classifying URLs. Fifth, we discuss preliminary findings from a study conducted on Amazon Mechanical Turk to examine why users fall for unsafe URLs. And sixth, we develop a logic-based representation of mismorphisms, which allows us to express the root causes of security problems. Each project demonstrates a key technique that can help in bridging the gap between intent and outcome

Metal tolerance in halotolerant bacteria isolated from saline soil of Khambhat

Five halotolerant bacteria were isolated from saline soil of Gujarat. Their identification and characterization with respect to optimum pH and salt concentration, and metal tolerance was carried out. Among all isolates Virgibacillus salarius exhibited better metal tolerance/resistance. In certain cases stimulatory effect of metal ions on growth was also observed. Such organisms can serve as a good model for study of stress response among prokaryotes, and can also be explored for their potential of bioremediation of metal polluted saline sites with alkaline pH

Fractionation of antibacterial extracts of Syzygium cumini (Myrtaceae) seeds

Antibacterial activity of Syzygium cumini seed extracts prepared in methanol and ethanol was evaluated by disc diffusion and broth dilution assays. Both extracts exerted a broad spectrum of bacteriostatic action against different gram-positive and gram-negative bacteria. Their minimum inhibitory concentration (MIC) against susceptible organisms ranged from 154-656 μg/mL. Highest total activity was registered by the ethanol extract against Staphylococcus epidermidis. Extracts were separated on TLC (thin-layer chromatography) plates, and separated components were individually tested  for their antibacterial activity. HPLC (high performance liquid chromatography) analysis indicated presence of gallic acid and quercetin in the methanolic extract

Effect of low power microwave on microbial growth, enzyme activity, and aflatoxin production

This study aimed at investigating the effect of low power (90 W) microwave radiation (2450 MHz) on microbial growth, enzyme activity (protease and urease), and aflatoxin production. Thermal effect was avoided by keeping inoculum in ice while treating with microwave (for varying duration i.e. 2, 4, and 6 min). After 6 min MW treatment to S. aureus, its growth was stimulated over control by ~10%. Total protease activity in Aeromonas hydrophila witnessed a 33% decrease as compared to control after a  microwave exposure of 2 min. Similar decrease of 24% in total protease activity of Candida albicans was observed after microwave exposure of 6 min. Staphylococcus aureus lost its urease activity completely after microwave treatment. Aflatoxin production was completely inhibited in Aspergillus parasiticus after microwave exposure of 2, 4, and 6 min. However, it required a 6 min microwave exposure for complete inhibition of aflatoxin production in Aspergillus flavus. Our results positively suggest existence of microwave specific non-thermal effect on microbial growth and metabolism

Microwave sterilized media supports better microbial growth than autoclaved media

Microwave treated media were compared with media sterilized through conventional autoclaving in terms of their ability to support microbial growth, spore germination, and revival of lyophilized bacterial cultures. Microwave sterilized media were found to support better microbial growth. Both bacteria and yeast were able to achieve higher cell density at a faster growth rate in microwaved media. Microwave treatment was found to be  suitable for media of varying compositions. Better retention of nutrient quality in microwave  treated growth media due to shorter heat exposure seems to be the major reason for better microbial growth in it. Microwave sterilization can prove an attractive alternative of conventional autoclaving, especially when media are needed for immediate use, and also when high biomass yield is of particular interest

In vitro antimicrobial activity of certain plant products / seed extracts against multidrug resistant Propionibacterium acnes, Malassezia furfur, and aflatoxin producing Aspergillus flavus

Seed extracts of five different plants viz. Phoenix sylvestris, Tamarindus indica, Syzygium cumini, Manilkara zapota, and Annona squamosa, prepared by microwave assisted extraction (MAE) method were screened for their antimicrobial activity against various human pathogenic microbes. Extraction efficiency ranged from 6-24%. Antimicrobial activity of seed extracts was investigated against three yeasts (Candida albicans, Saccharomyces cerevisae, Malassezia furfur), one mold (Aspergillus flavus) and one anaerobic bacterium (Propionibacterium acnes) by broth dilution assay and minimum inhibitory concentration (MIC) was determined. Methanolic extract of T. indica and S. cumini inhibited 60% of test organisms. Amongst the microorganisms tested, the most resistant was found to be C. albicans and the most susceptible was M. furfur. Effect of eight seed extracts on aflatoxin production by A. flavus was also investigated. Ethanolic extract of A. squamosa caused 100% inhibition of aflatoxin production at 500 µg/mL

Effect of certain phytochemicals on Aeromonas hydrophila

This study was aimed at investigating effect of different phytochemicals on growth of Aermonas hydrophila. Susceptibility of A. hydrophila to seven different phytocompounds was evaluated by broth dilution assay. Among all the test compounds curcumin with a minimum inhibitory concentration of ~175 μg/ml was found to be most effective against A. hydrophila, followed by tannic acid. Gallic acid failed to show any effect on growth of the test organism. A growth curve study in absence and presence of curcumin was also made. Since A. hydrophila is viewed as a challenging and notorious food-borne pathogen, and difficult to control owing to its resistance to many antibiotics, it is required to find novel approaches to control it. Our study found curcumin to be effective against this organism as a bacteriostatic agent at microgram concentrations

Development of mathematical model to predict vertical wicking behaviour. Part I : flow through yarn

Theoretical models have been proposed in this article (Parts I and II) to predict the vertical wicking behaviour of yarns and fabrics based on different fibre, yarn and fabric parameters. The first part of this article deals with the modelling of flow through yarn during vertical wicking, whereas the second part deals with the modelling of vertical wicking through the fabric. The yarn model has been developed based on the Laplace equation and the Hagen– Poiseuille’s equation on fluid flow; pore geometry has been determined as per the yarn structure. Factors such as fibre contact angle, number of filaments in a yarn, fibre denier, fibre cross-sectional shape, yarn denier and twist level in the yarn have been taken into account for development of the model. Lambertw, a mathematical function, has been incorporated, which helps to predict vertical wicking height at any given time, considering the gravitational effects. Experimental verification of the model has been carried out using polyester yarns. The model was found to predict the wicking height with time through the yarns with reasonable accuracy. Based on the proposed yarn model, a mathematical model has been developed to predict the vertical wicking through plain woven fabric in the second part of this article

In vitro antimicrobial activity in certain plant products / seed extracts against selected phytopathogens

Extracts of five different plant seeds- Syzygium cumini, Pheonix sylvestris, Manilkara zapota, Tamarindus indica, and Annona squamosa- prepared by Microwave Assisted Extraction (MAE) method were screened for their antimicrobial activity against certain phytopathogenic microorganisms. Ethanolic extract of S. cumini was found to possess highest average total activity against susceptible microbes. Total activity was found to have a positive correlation with the extraction efficiency. Methanolic extract of T. indica exerted bactericidal action against Agrobacterium tumefaciens and Pseudomonas syringae. Ethanolic extract of P. sylvestris was able to protect cabbage leaf against Xanthomonas campestris. Acetone extract of M. zapota was able to reduce aflatoxin production in Aspergillus parasiticus by >50 %. Curcumin proved bactericidal against X. campestris