Lipid biomarker analysis and stable carbon isotope studies of biofilms in the Green Valley acid mine drainage site, Indiana, U.S.A.

Lipids were extracted in order to explore the microbial communities in eleven biofilms and four layers of two stromatolite samples, from the Green Valley acid mine drainage site in western Indiana. The high concentrations of phytadiene, polyunsaturated fatty acids, phytol, phytanol, and monounsaturated fatty acid 18:1Δ9 in the biofilms indicated the abundance of phototrophs, including microeukaryotes, algae (mainly diatoms), and fungi. Wax esters in the hydrocarbon fraction possibly suggested the presence of localized anaerobic zones within the biofilms, where the microeukaryotes synthesized the esters by an unusual reverse β-oxidation pathway. Other microbial communities in the biofilms mainly included sulfate-reducing bacteria (SRB), and Gram-positive bacteria. The contribution of cyanobacteria to the lipid pool was not very significant. The trans/cis ratio of monounsaturated fatty acids can be a good indicator of the physiology of the biofilms, indicating whether it is attached or floating, and further depicting the nutrient conditions in which they thrive. The primary cause of 13C enrichment in the GVS biomarkers has been attributed to a carbon-limiting system existing in the mine environment. The depletion of carbon is the result of increased sulfate, resulting in lowering of pH in the AMD. Both autotrophic and heterotrophic eukaryotes were detected by the biomarker study. While the autotrophs used aqueous CO2 for carbon fixation, heterotrophs either used the autotrophic dissolved organic carbon (DOC) or C3/C4 organic matter for the same. A model for carbon flow has been proposed to explain the biogeochemistry in GVS

Improvise, Adapt, Overcome: Dynamic Resiliency Against Unknown Attack Vectors in Microgrid Cybersecurity Games

Cyber-physical microgrids are vulnerable to rootkit attacks that manipulate system dynamics to create instabilities in the network. Rootkits tend to hide their access level within microgrid system components to launch sudden attacks that prey on the slow response time of defenders to manipulate system trajectory. This problem can be formulated as a multi-stage, non-cooperative, zero-sum game with the attacker and the defender modeled as opposing players. To solve the game, this paper proposes a deep reinforcement learning-based strategy that dynamically identifies rootkit access levels and isolates incoming manipulations by incorporating changes in the defense plan. A major advantage of the proposed strategy is its ability to establish resiliency without altering the physical transmission/distribution network topology, thereby diminishing potential instability issues. The paper also presents several simulation results and case studies to demonstrate the operating mechanism and robustness of the proposed strategy

Design automation and analysis of three-dimensional integrated circuits

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 165-176).This dissertation concerns the design of circuits and systems for an emerging technology known as three-dimensional integration. By stacking individual components, dice, or whole wafers using a high-density electromechanical interconnect, three-dimensional integration can achieve scalability and performance exceeding that of conventional fabrication technologies. There are two main contributions of this thesis. The first is a computer-aided design flow for the digital components of a three-dimensional integrated circuit (3-D IC). This flow primarily consists of two software tools: PR3D, a placement and routing tool for custom 3-D ICs based on standard cells, and 3-D Magic, a tool for designing, editing, and testing physical layout characteristics of 3-D ICs. The second contribution of this thesis is a performance analysis of the digital components of 3-D ICs. We use the above tools to determine the extent to which 3-D integration can improve timing, energy, and thermal performance. In doing so, we verify the estimates of stochastic computational models for 3-D IC interconnects and find that the models predict the optimal 3-D wire length to within 20% accuracy. We expand upon this analysis by examining how 3-D technology factors affect the optimal wire length that can be obtained. Our ultimate analysis extends this work by directly considering timing and energy in 3-D ICs. In all cases we find that significant performance improvements are possible. In contrast, thermal performance is expected to worsen with the use of 3-D integration. We examine precisely how thermal behavior scales in 3-D integration and determine quantitatively how the temperature may be controlled during the circuit placement process. We also show how advanced packaging(cont.) technologies may be leveraged to maintain acceptable die temperatures in 3-D ICs. Finally, we explore two issues for the future of 3-D integration. We determine how technology scaling impacts the effect of 3-D integration on circuit performance. We also consider how to improve the performance of digital components in a mixed-signal 3-D integrated circuit. We conclude with a look towards future 3-D IC design tools.by Shamik Das.Ph.D

Studies on Multifunctional Effect of All-Trans Retinoic Acid (ATRA) on Matrix Metalloproteinase-2 (MMP-2) and Its Regulatory Molecules in Human Breast Cancer Cells (MCF-7)

Background. Vitamin A derivative all-trans retinoic acid (ATRA) is considered as a potent chemotherapeutic drug for its capability of regulating cell growth and differentiation. We studied the effect of ATRA on MMP-2 in MCF-7, human breast cancer cells, and the probable signaling pathways which are affected by ATRA on regulating pro-MMP-2 activity and expression. Methods. Gelatin zymography, RT-PCR, ELISA, Western blot, Immunoprecipitation, and Cell adhesion assay are used. Results. Gelatin zymography showed that ATRA caused a dose-dependent inhibition of pro-MMP-2 activity. ATRA treatment downregulates the expression of MT1-MMP, EMMPRIN, FAK, NF-kB, and p-ERK. However, expression of E-cadherin, RAR, and CRABP increased upon ATRA treatment. Binding of cells to extra cellular matrix (ECM) protein fibronectin reduced significantly after ATRA treatment. Conclusions. The experimental findings clearly showed the inhibition of MMP-2 activity upon ATRA treatment. This inhibitory effect of ATRA on MMP-2 activity in human breast cancer cells (MCF-7) may result due to its inhibitory effect on MT1-MMP, EMMPRIN, and upregulation of TIMP-2. This study is focused on the effect of ATRA on MMP, MMP-integrin-E-cadherin interrelationship, and also the effect of the drug on different signaling molecules which may involve in the progression of malignant tumor development

Nanowire nanocomputer as a finite-state machine

Implementation of complex computer circuits assembled from the bottom up and integrated on the nanometer scale has long been a goal of electronics research. It requires a design and fabrication strategy that can address individual nanometer-scale electronic devices, while enabling large-scale assembly of those devices into highly-organized, integrated computational circuits. We describe how such a strategy has led to the design, construction, and demonstration of a nanoelectronic finite-state machine (nanoFSM). The system was fabricated using a design- oriented approach enabled by a deterministic, bottom-up assembly process that does not require individual nanowire registration. This methodology allowed construction of the nanoFSM through modular design employing a multi-tile architecture. Each tile/module consists of two interconnected crossbar nanowire arrays, with each cross-point consisting of a programmable nanowire transistor node. The nanoFSM integrates 180 programmable nanowire transistor nodes in three tiles or six total crossbar arrays, and incorporates both sequential and arithmetic logic, with extensive inter-tile and intra-tile communication that exhibits rigorous input/output (I/O) matching. Our system realizes the complete 2-bit logic flow and clocked control over state registration that are required for a FSM or computer. The programmable multi-tile circuit was also re-programmed to a functionally-distinct 2-bit full adder with 32-set matched and complete logic output. These steps forward and the ability of our new design-oriented deterministic methodology to yield more extensive multi-tile systems, suggest that proposed general-purpose nanocomputers can be realized in the near future.Chemistry and Chemical BiologyEngineering and Applied Science