Phytoplankton Community Distribution and Light Absorption Properties in the Northern Gulf of Mexico

The theme of this dissertation was to understand the spatio-temporal dynamics of the phytoplankton community, its light absorption properties, and its relationship to underlying physicochemical processes. Understanding these phenomena will benefit efforts to predict pathways of carbon transformation in the ocean, to estimate primary productivity (PP) and to characterize distributions of phytoplankton communities using ocean color remote sensing. This research entailed four different studies, which address different objectives. The first two studies dealt with phytoplankton community composition and its relationship to environmental variables. A chemotaxonomic approach was used, which was successful in revealing distinct phytoplankton assemblages in distinct water mass regimes. In the second study, a multivariate statistical analysis was used to examine community responses to seasonal variability in relation to different meteorological and environmental forcing. Clear differences in phytoplankton communities existed between stratified and non-stratified periods. Understanding the variability in the dominant light absorption constituents in the continental margin of northern Gulf of Mexico was the subject of the fourth study. Absorption budgets for the region revealed dominance of colored dissolved organic matter (CDOM). The presence of large contributions from the CDOM and non-algal particles (NAP) can lead to over- or underestimation of chlorophyll-a specific phytoplankton absorption (a*ϕ) and such errors may then propagate to errors in PP estimates using current ocean color algorithms. Additionally, variations in the optical characteristics of phytoplankton also influence PP. Thus, the fourth study focused on describing the main sources of bio-optical variability affecting the spectral signatures of phytoplankton absorptions in the region. Results showed that changes in cell size, pigment composition and photoacclimation strongly affected phytoplankton spectral absorption. Values of a*ϕ were largely influenced by the pigment package effect and cell size followed by pigment composition. The results from this study will benefit efforts to examine the critical role of phytoplankton in biogeochemical cycles of the northern Gulf of Mexico

Chemical diffusivity of boron in melts of haplogranitic composition

Chemical diffusivities of B in synthetic melts of haplogranitic composition have been measured by the diffusion couple technique at 1 atm between 1200–1600°C. The compositional profiles were measured by ion microprobe and modelled using the Boltzmann-Matano formalism to retrieve compositionally dependent interdiffusion coefficients. At the experimental conditions, B2O3 is found to exchange primarily with SiO2 and the interdiffusion coefficient increases with increasing replacement of Si by B in the melt. No isotopic fractionation of boron was observed in the diffusion zone at the experimental conditions. The compositional dependence of diffusivity increases with decreasing temperature. The activation energy of diffusion (~70 kcal) is similar to that for viscous flow in melts of the same composition and is relatively insensitive to B content between 1–10 wt% B2O3 in the melt. However, the addition of the initial 1 wt% B2O3 to a haplogranitic melt appears to dramatically lower the activation energy for these processes from ~ 100 kCal to ~70 kCal. Thus, common geochemical concentrations of B may affect petrogenesis of granitic rocks by their influence on these transport properties. Some implications of these results for crystal growth and dissolution in B-bearing melts and boron isotopic variation of granitic melts have been discussed. If diffusion is the rate-limiting process, boron isotopic heterogeneity may be maintained in granitic melts at magmatic temperatures on time scales of millions of years on a millimeter scale. The influence of small amounts of B on transport properties may also contribute toward resolution of an enigma regarding emplacement mechanisms of peraluminous granites

SECURE MULTI-PARTY COMPUTATION: HOW TO SOLVE THE CONFLICT BETWEEN SECURITY & BUSINESS INTELLIGENCE

Abstract: This work defines the security intelligence of a system based on secure multi-party computation in terms of correctness, fairness, rationality, trust, honesty, transparency, accountability, reliability, consistency, confidentiality, data integrity, non-repudiation, authentication, authorization, correct identification, privacy, safety and audit. It defines the security intelligence of a system comprehensively with a novel concept of collective intelligence. The cryptographic notion of security is applied to assess, analyze and mitigate the risks of bio-terrorism today. The definition of bioterrorism has been changed in terms of information security. This work also tries to resolve the conflict between the security intelligence and business intelligence in the context of bio-terrorism and highlights the new cryptographic challenges. Keywords: Security intelligence, Threat analytics, Business intelligence, Cross border bio-terrorism, Secure multi-party computation, Applied cryptography

Algorithmic Mechanism Construction bridging Secure Multiparty Computation and Intelligent Reasoning

This work presents the construction of intelligent algorithmic mechanism based on multidimensional view of intelligent reasoning, threat analytics, cryptographic solutions and secure multiparty computation. It is basically an attempt of the cross fertilization of distributed AI, algorithmic game theory and cryptography. The mechanism evaluates innate and adaptive system immunity in terms of collective, machine, collaborative, business and security intelligence. It also shows the complexity analysis of the mechanism and experimental results on three test cases: (a) intrusion detection, (b) adaptively secure broadcast and (c) health security

Financial Cryptography: Algorithmic Mechanisms for a Hedonic Game

A (or a group of) selling agent wants to allocate and sell a (or a set of) parcel of land optimally and fairly to a buying agent within the capacity constraint of the selling agent and budget constraint of the buying agent. This problem has been solved by combining the concept of algorithmic cooperative game theory and financial cryptography. This is an approach for a group of decision-making agents to reach a mutually beneficial agreement through compromise and stable matching of preference. The work presents a cooperative game and a set of algorithmic coordination mechanisms: SBSS, SBMS (for collective and non-collective bargaining in holdout problem) and MBSS. The game is characterized by a set of agents, inputs, strategic moves, revelation principle, payment function and outputs. The coordination mechanisms are designed based on domain planning, rational fair data exchange and compensation negotiation. These mechanisms preserve the privacy of strategic data through secure multi-party computation (SMC), more specifically solving Yao’s millionaire problem. The mechanisms are analyzed from the perspectives of revelation principle, computational intelligence and communication complexity. The communication complexity depends on the time constraint of the negotiating agents, their information state and the number of negotiation issues. The computational complexity depends on the valuation of pricing plan, compensation estimation and private comparison. It is a mixed strategy game; both sequential and simultaneous moves can be applied intelligently to search a neighborhood space of core solutions

Financial Cryptography: Discriminatory Pricing Mechanism

This work presents an adaptive profitable discriminatory pricing mechanism for cloud computing based on secure function decomposition, cryptographic commitments and zero knowledge proof. Cloud computing is an emerging trend of enterprise resource planning where a selling agent or service provider (S) wants to allocate a set of computational resources and related IT services optimally and fairly among many buying agents or service consumers (B) within its capacity constraint. Each service consumer discloses its demand plan for an IT portfolio within its budget constraint and rank of preference. An IT portfolio may include SaaS, PaaS, IaaS, CaaS, DaaS and dSaaS. The basic objective of the service provider is to optimize its expected revenue within target profit margin. It is basically a problem of secure function evaluation where the concept of decomposition of a function is considered. It is a constrained non-linear optimization problem; the search is governed by a set of intelligent moves. The communication complexity of the pricing mechanism depends on the time constraint of the negotiating agents, their information state and the number of negotiation issues; it also depends on number of negotiation rounds and the complexity of IT portfolio. The computational cost depends on the complexity of function decomposition. The security and privacy of strategic data of the trading agents provides business intelligence to the pricing mechanism. The ultimate objective of the mechanism is to predict a profitable discriminatory pricing plan for each consumer

Mobile Commerce: Secure Multi-party Computation & Financial Cryptography

Abstract: The basic objective of this work is to construct an efficient and secure mechanism for mobile commerce applying the concept of financial cryptography and secure multi-party computation. The mechanism (MCM) is defined by various types of elements: a group of agents or players, actions, a finite set of inputs of each agent, a finite set of outcomes as defined by output function, a set of objective functions and constraints, payment function, a strategy profile, dominant strategy and revelation principle. The mechanism adopts a set of intelligent moves as dominant strategies: (a) flexible use of hybrid payment system which supports cash, e-payment and m-payment, (b) secure multi-party computation to ensure information security and privacy and (c) call intelligent analytics to assess and mitigate possible threats on m-commerce service. The mechanism supports three different types of transaction processing protocols (P1, P2 and P3) and calls a cryptographic protocol (Pc). The cryptographic protocol performs a set of functions sequentially such as authentication, authorization, correct identification, privacy verification and audit of correctness, fairness, rationality, accountability and transparency of secure multi-party computation on each m-transaction. The basic building blocks of the cryptographic protocol are signcryption, proofs of knowledge, commitments and secret sharing. This work also presents the complexity analysis of the mechanism in terms of computational cost, communication cost, security and business intelligence. Keywords: Secure multi-party computation, Financial cryptography, Mobile commerce mechanism, Threat analytics, Digital econom