Adaptive Mechanisms of an Estuarine Synechococcus based on Genomics, Transcriptomics, and Proteomics

Picocyanobacteria are important phytoplankton and primary producers in the ocean. Although extensive work has been conducted for picocyanobacteria (i.e. Synechococcus and Prochlorococcus) in coastal and oceanic waters, little is known about those found in estuaries like the Chesapeake Bay. Synechococcus CB0101, an estuarine isolate, is more tolerant to shifts in temperature, salinity, and metal toxicity than coastal and oceanic Synechococcus strains, WH7803 and WH7805. Further, CB0101 has a greater sensitivity to high light intensity, likely due to its adaptation to low light environments. A complete and annotated genome sequence of CB0101 was completed to explore its genetic capacity and to serve as a basis for further molecular analysis. Comparative genomics between CB0101, WH7803, and WH7805 show that CB0101 contains more genes involved in regulation, sensing, and stress response. At the transcript and protein level, CB0101 regulates its metabolic pathways, transport systems, and sensing mechanisms when nitrate and phosphate are limited. Zinc toxicity led to oxidative stress and a global down regulation of photosystems and the translation machinery. From the stress response studies seven chromosomal toxin-antitoxin (TA) genes, were identified in CB0101, which led to the discovery of TA genes in several marine Synechococcus strains. The activation of the relB2/relE1 TA system allows CB0101 to arrest its growth under stressful conditions, but the growth arrest is reversible, once the stressful environment dissipates. The genome of CB0101 contains a relatively large number of genomic island (GI) genes compared to known marine Synechococcus genomes. Interestingly, a massive shutdown (255 out of 343) of GI genes occurred after CB0101 was infected by a lytic phage. On the other hand, phage-encoded host-like proteins (hli, psbA, ThyX) were highly expressed upon phage infection. This research provides new evidence that estuarine Synechococcus like CB0101 have inherited unique genetic machinery, which allows them to be versatile in the estuarine environment.

Sobre (vivência) e mortalidade de pequenos negócios: o caso de mercados varejistas potiguares

This paper‟s starting point was the objective of understanding the relation between the reasons pointed out by small businesses owners for the continuity or shutdown of their businesses, and the reasons presented by the Environmental Theories. The paper discusses the Environmental Theories understand that it is supported by a systemic metaphor speech, discussing the theme in terms of organizational survival and mortality . The text reviews the literature showing the changes in the administrative thinking regarding the organization versus environment relation, and presenting general ideas about the micro and small businesses. In methodological terms, the qualitative approach was used in the research. Regarding the data collection technique, an in-depth thematic interview was used. It was carried out considering the elements of the techniques of life history and oral history, always giving priority to real world related narratives told by the interviewed subjects. The empirical corpus of the research was made up of seven owners of small retail businesses in two Potiguar cities: Natal and Mossoró. The interpretative and analytical process focused, at first, on the reflexive dialogue with each one of the owners‟ professional life history and business management experience, constituting the first level of analysis: reflections on individual narratives; and, afterwards, the interpretative process was developed through the analysis of all the subjects‟ statements, identifying the recurring themes and constituting the second level of analysis: reflection on the totalizing narrative. The themes identified in the totalizing narrative, that refer to the continuity of the businesses are: evolution, control, fidelity, liking what one does for a living. The themes that came up as reasons for shutdown are: lack of empathy with the business, lack of evolution, competition problems, suppliers and the government. The text synthesizes its comprehensions affirming that the reasons associated with continuity and shutdown of small markets, for this group of owners specifically, come up as a permanent tension between the volunteerism (quite human) and the determinism (systemic). The tension is shown in testimonies that at the same time evoke the organicist systemic logic through the themes evolution/no evolution, and also counterpoints with themes related to the interested human action, based on desires, feelings and personal convictions such as: liking what one does/ lack of empathy. As for the reflexive dialogue between the postulates of the Environmental Theories and the narratives, the results make it possible to affirm that, differently from the tension expressed by the subjects while talking about their reasons, the reasons associated with survival and mortality of businesses according to the Environmental Theories are theoretically polarized, seeming to preach options that are stagnated and shaping towards the subjects involved in the organization-environment relation

Physical Design Methodologies for Low Power and Reliable 3D ICs

As the semiconductor industry struggles to maintain its momentum down the path following the Moore's Law, three dimensional integrated circuit (3D IC) technology has emerged as a promising solution to achieve higher integration density, better performance, and lower power consumption. However, despite its significant improvement in electrical performance, 3D IC presents several serious physical design challenges. In this dissertation, we investigate physical design methodologies for 3D ICs with primary focus on two areas: low power 3D clock tree design, and reliability degradation modeling and management. Clock trees are essential parts for digital system which dissipate a large amount of power due to high capacitive loads. The majority of existing 3D clock tree designs focus on minimizing the total wire length, which produces sub-optimal results for power optimization. In this dissertation, we formulate a 3D clock tree design flow which directly optimizes for clock power. Besides, we also investigate the design methodology for clock gating a 3D clock tree, which uses shutdown gates to selectively turn off unnecessary clock activities. Different from the common assumption in 2D ICs that shutdown gates are cheap thus can be applied at every clock node, shutdown gates in 3D ICs introduce additional control TSVs, which compete with clock TSVs for placement resources. We explore the design methodologies to produce the optimal allocation and placement for clock and control TSVs so that the clock power is minimized. We show that the proposed synthesis flow saves significant clock power while accounting for available TSV placement area. Vertical integration also brings new reliability challenges including TSV's electromigration (EM) and several other reliability loss mechanisms caused by TSV-induced stress. These reliability loss models involve complex inter-dependencies between electrical and thermal conditions, which have not been investigated in the past. In this dissertation we set up an electrical/thermal/reliability co-simulation framework to capture the transient of reliability loss in 3D ICs. We further derive and validate an analytical reliability objective function that can be integrated into the 3D placement design flow. The reliability aware placement scheme enables co-design and co-optimization of both the electrical and reliability property, thus improves both the circuit's performance and its lifetime. Our electrical/reliability co-design scheme avoids unnecessary design cycles or application of ad-hoc fixes that lead to sub-optimal performance. Vertical integration also enables stacking DRAM on top of CPU, providing high bandwidth and short latency. However, non-uniform voltage fluctuation and local thermal hotspot in CPU layers are coupled into DRAM layers, causing a non-uniform bit-cell leakage (thereby bit flip) distribution. We propose a performance-power-resilience simulation framework to capture DRAM soft error in 3D multi-core CPU systems. In addition, a dynamic resilience management (DRM) scheme is investigated, which adaptively tunes CPU's operating points to adjust DRAM's voltage noise and thermal condition during runtime. The DRM uses dynamic frequency scaling to achieve a resilience borrow-in strategy, which effectively enhances DRAM's resilience without sacrificing performance. The proposed physical design methodologies should act as important building blocks for 3D ICs and push 3D ICs toward mainstream acceptance in the near future.

O habitus militar e as práticas da tortura na ditadura militar no Brasil (1964-1985)

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Sociais, Departamento de Sociologia, 2016.

Behavioural correlation for detecting P2P bots

In the past few years, IRC bots, malicious programs which are remotely controlled by the attacker through IRC servers, have become a major threat to the Internet and users. These bots can be used in different malicious ways such as issuing distributed denial of services attacks to shutdown other networks and services, keystrokes logging, spamming, traffic sniffing cause serious disruption on networks and users. New bots use peer to peer (P2P) protocols start to appear as the upcoming threat to Internet security due to the fact that P2P bots do not have a centralized point to shutdown or traceback, thus making the detection of P2P bots is a real challenge. In response to these threats, we present an algorithm to detect an individual P2P bot running on a system by correlating its activities. Our evaluation shows that correlating different activities generated by P2P bots within a specified time period can detect these kind of bots.

Habitar o Claustro

Dissertação para obtenção do grau de Mestre em Arquitectura, apresentada na Universidade de Lisboa - Faculdade de Arquitectura.

Economic impact of political protests (strikes) on manufacturing firms : evidence from Bangladesh

Political protests in the form of strikes, locally known as hartal, remain quite common in the Indian subcontinent countries. Such a form of protests is associated with mass movement, intended to cause a total shutdown of economic activities and often results in coercion, violence, and damage to both public and private properties. Utilizing the World Bank Enterprise survey data of 2007 and 2013 of Bangladesh, this study examines the impacts of hartals on manufacturing firms. We find that political protests significantly increase costs for firms. Using flexible cost function based on factor analysis we see that the factor-neutral effect of strikes is positive and statistically significant, showing evidence of a reduction in firm productivity due to hartals. However, we did not find any evidence for systematic factor re-optimization by firms – in response to political strikes – suggesting that firms do not reallocate factor shares to tackle uncertain and irregular shocks like hartals.

Cold acclimation of chill coma mechanisms in the locust CNS

Temperature has profound effects on the neural function and behaviour of insects. When exposed to low temperature, migratory locusts (Locusta migratoria) enter chill coma (neuromuscular paralysis) and can resume normal body functions after returning to normal temperature. Our laboratory has studied phenomena underlying environmental stress-induced comas in locusts and found that they are associated with a sudden loss of K+ homeostasis and also a temporary electrical silence in the central nervous system (CNS). However, the mechanisms underlying chill coma entry and recovery are not well understood, particularly the role of the CNS has not been determined. Here, I investigated neural function during chill coma in the locust by measuring electrical activity in the CNS. As pre-exposure to moderately low temperatures, either chronically (cold acclimation) or acutely (rapid cold hardening; RCH), has been found to improve the insect’s cold tolerance, I also determined cold acclimation and RCH protocols that will improve the locust's cold tolerance and whether these protocols affect neural shutdown during chill coma in the locust. With an implanted thermocouple in the thorax, I determined the temperature associated with a loss of responsiveness (CTmin) in intact male adult locusts. In parallel experiments, I recorded field potential (FP) in the metathoracic ganglion (MTG) in semi-intact preparations to determine the temperature that would induce neural shutdown. I found that acclimation at 10 ˚C and RCH at 4 ˚C reduced chill coma recovery time (CCRT) in intact animal preparations and RCH at 4 ˚C for 4 hours reduced the temperature at neural shutdown in semi-intact preparations. These results suggest that pre-exposure to cold can improve the locust's resistance to chill coma and support the notion that the CNS has a role in determining entry into and exit from chill coma in locusts.