The Origin Of The Cabacal Cu-au Deposit, Alto Jauru Greenstone Belt, Brazil

The Cabacal Deposit is located in the southern part of the Amazonian Craton (Brazil). It is hosted within the felsic volcanic and volcanoclastic rocks of the Proterozoic Alto Jauru Greenstone Belt.;The processes leading to the deposit are under debate. Some consider the Cabacal Deposit to be of shear-related origin, whereas some interpreted it to be a syngenetic deposit. The present study concludes that the Cabacal Deposit is a deformed volcanogenic massive sulphide deposit. The age of the volcanic system is around 1.7Ga, and of deformation is around 1.6Ga.;Host rocks are commonly sheared parallel to lithological boundaries. Intensive alteration affected the host rocks in the vicinity of the ore bodies. This alteration zone consists of an inner chloritized core, surrounded by a sericitic zone similar to those that occur in VMS deposits. The felsic volcanic host rocks have chemical characteristics pointing to their generation in an island arc environment.;Of the intrusive bodies of the area, the Cabacal Tonalites have some chemical similarities with the felsic volcanic rocks from the Manuel Leme Formation. They also show characteristics of an island arc environment. Possibly, the intrusion took place simultaneously with the shear that affected that area.;Ore in Cabacal is distributed in three zones (South, Central and East Copper Zones) composed of a portion rich in copper and a stringer zone of quartz and sulphide veins. The Central Copper Zone shows a massive sulphide body. Mineralization occurs as landed, veined, breccia and massive ore.;The first mineralizing event in Cabacal is syngenetic with the Manuel Leme formation deposition and it generated a VMS deposit. The second mineralizing event is deformation-related, and redistributed gold into structural features, creating zones with high gold grades. Different fluids were involved in the first mineralization event. Geochemical and thermometric studies suggest fluids with low salinities and of a wide range in temperature (240 to 340{dollar}\sp\circ{dollar}C). Gold transport occurred as Au(HS){dollar}\sp-\sb2{dollar} or AuCl{dollar}\sp-\sb2,{dollar} depending on the associated paragenesis. Results of oxygen isotope studies indicate a fluid with low {dollar}\delta\sp{lcub}18{rcub}{dollar}O ({dollar}-{dollar}2.85 to +2.3), similar to those from the Kuroko mines

Regulação do canal de magnésio MgtE por di-AMP cíclico

Cells are complex, adaptable systems that maintain a tight control over the concentration gradients of inorganic ions like K⁺, Na⁺, Cl⁻, Ca²⁺ and Mg²⁺, vital for a host of cellular functions like pH regulation, osmolarity control, electrical activity, and cellular communication. For this purpose, cells possess a variety of transporters and channels that facilitate their passage through the cell membrane. Magnesium (Mg²⁺) is the second most abundant intracellular cation, an important enzyme cofactor, structural component, and stabilizer of DNA. In Bacteria, several channels and transporters regulate Mg²⁺ influx and efflux, including the MgtE channel. MgtE possesses a cystathionine-β-synthase domain, the CBS domain, that can bind adenosine-containing ligands, with regulatory functions in other transporters. Among such ligands, we find cyclic-di-AMP, a cyclic nucleotide second messenger that modulates K⁺ transport at several levels and has been proposed to bind to MgtE. Recently, changes in intracellular Mg²⁺, K⁺ and cyclic-di-AMP concentrations were observed during osmotic stress response. The main goal of this work is to prove that cyclic-di-AMP binds to MgtE from B. subtilis, a model Gram-position bacteria, and to explore its effects on Mg²⁺ transport through MgtE. In this work, functional assays were performed, confirming MgtE’s role as a Mg²⁺ channel, but no conclusive results about cyclic-di-AMP’s effects were obtained. Large-scale expression and purification of MgtE’s N-terminal domain (containing the CBS sub-domain) were performed, followed by structural assays. Differential scanning fluorimetry assays identified cyclic-di-AMP as a ligand, and isothermal titration calorimetry determined that binding occurs with a dissociation constant KD of 1.75 μM and a stoichiometry of 1:4 cyclic-di-AMP to MgtE molecules. Size-exclusion chromatography revealed that MgtE’s cytosolic domain undergoes a conformational change, supporting the oligomerization of the domain in the presence of cyclic-di-AMP. Finally, crystallography assays yielded several crystals for analysis, but the structure of the protein-ligand complex could not be resolved due to poor crystal quality.As células são sistemas complexos e adaptáveis que mantêm um controlo apertado sobre os gradientes de concentração de iões inorgânicos como K⁺, Na⁺, Cl⁻, Ca²⁺ e Mg²⁺, vitais para uma série de funções celulares como a regulação de pH, o controlo de osmolaridade, a actividade eléctrica, e a comunicação celular. Para este fim, as células possuem uma variedade de transportadores e canais que facilitam a sua passagem através da membrana celular. O magnésio (Mg²⁺) é o segundo catião intracelular mais abundante, um importante cofactor enzimático, componente estrutural, e estabilizador do ADN. Em Bacteria, vários canais e transportadores regulam o influxo e efluxo de Mg²⁺, incluindo o canal MgtE. O MgtE possui um domínio de cistathionine-β-synthase, o domínio CBS, que pode ligar ligandos contendo adenosina, com funções reguladoras noutros transportadores. Entre esses ligandos, encontramos o di-AMP cíclico um mensageiro segundário de nucleótido cíclico que modula o transporte de K⁺ a vários níveis e que foi proposto ligar-se ao MgtE. Recentemente, foram observadas alterações nas concentrações intracelulares de Mg²⁺, K⁺ e di-AMP cíclico durante a resposta ao stress osmótico. O principal objectivo deste trabalho é provar que o di-AMP cíclico se liga ao MgtE de B. subtilis, uma bactéria Gram-positiva modelo, e explorar os seus efeitos no transporte de Mg²⁺ através do MgtE. Neste trabalho, foram realizados ensaios funcionais, confirmando o que o MgtE é um canal de Mg²⁺, mas não foram obtidos resultados conclusivos sobre os efeitos do di-AMP cíclico. Foram realizadas a expressão e purificação em grande escala do domínio N-terminal do MgtE (contendo o sub-domínio CBS), seguidos de ensaios estruturais. Os ensaios de fluorimetria de varrimento diferencial identificaram o di-AMP cíclico como um ligando, e a calorimetria isotérmica de titulação determinou que a ligação ocorre com uma constante de dissociação KD de 1,75 μM e uma estequiometria de 1:4 moléculas de di-AMP cíclico para moléculas de MgtE. A cromatografia de exclusão de tamanho revelou que o domínio citosólico do MgtE sofre uma alteração conformacional, apoiando a oligomerização do domínio na presença do di-AMP cíclico. Finalmente, os ensaios de cristalografia produziram vários cristais para análise, mas a estrutura do complexo proteína-ligando não pôde ser resolvida devido à má qualidade dos cristais.Mestrado em Biologia Aplicad

Intrusion detection based on behavioral rules for the bytes of the headers of the data units in IP networks

Nowadays, communications through computer networks are of utmost importance for the normal functioning of organizations, worldwide transactions and content delivery. These networks are threatened by all kinds of attacks, leading to traffic anomalies that will eventually disrupt the normal behaviour of the networks, exploring specific breaches on a system component or exhausting network resources. Automatic detection of these network anomalies comprises one of the most important resources for network administration, and Intrusion Detection Systems(IDSs) are amongst the systems responsible for this automatic detection. This dissertation starts from the assumption that it is possible to use machine learning to, consistently and automatically, produce rules for an intrusion detector based on statistics for the first 64 bytes of the headers of Internet Protocol (IP) packets. The survey on the state of the art on related works and currently available IDSs shows that the specific approach taken here is worth to be explored. The decision tree learning algorithm known as C4.5 is identified as a suitable means to produce the aforementioned rules, due to the similarity between their syntax and the tree structure. Several rules are then devised using the ML approach for several attacks. The attacks were the same used in a previous work, in which the rules were devised manually. Both rule sets are then compared to show that, in fact, it is possible to construct rules using the approach taken herein, and that the rules created resorting to the C4.5 algorithm are superior to the ones devised after thorough human analysis of several statistics calculated for the bytes of the headers of the packets. To compare them, each rule set was used to detect intrusions in third party traces containing attacks and in live traffic during simulation of attacks. Most of the attacks producing noticeable impact on the headers were detected by both rule sets, but the results for the third party traces were better in the case of the ML devised rules, providing a clear evidence for the aforementioned assumptions.Hoje em dia, as comunicações através de redes informáticas são da maior importância para o normal funcionamento das organizações, transações mundiais e entrega de conteúdos. Essas redes são ameaçadas por todo o tipo de ataques, levando a anomalias no tráfego, que eventualmente vão corromper o normal funcionamento da rede, explorando falhas específicas num componente de um sistema, ou esgotando os recursos de rede. A deteção automática dessas anomalias de rede é um dos recursos mais importantes para os administradores de rede, e os Sistemas de Deteção de Intrusões estão entre os sistemas responsáveis por essa deteção. Esta dissertação tem como ponto de partida, a assunção que é possível usar mecanismos de aprendizagem automática para produzir, de modo consistente e automático, regras para a deteção de intrusões, baseadas em estatísticas dos primeiros 64 bytes dos cabeçalhos dos pacotes IP. O estudo sobre o estado da arte em trabalhos da área, e em sistemas de deteção atualmente disponíveis, mostrou que o método usado nesta dissertação merece ser estudado. O algoritmo de árvores de decisão C4.5 foi identificado como um meio apropriado para produzir as regras já referidas, devido à semelhança entre a sintaxe das mesmas e a estrutura em árvore deste algoritmo. Várias regras foram depois produzidas para vários tipos de ataque, usando a abordagem por aprendizagem automática. Os ataques tomados em consideração foram os mesmos que foram utilizados num trabalho anterior, em que a regras foram concebidas manualmente. Ambos os conjuntos de regras são depois comparados, para mostrar que, de facto, é possível construir regras através da abordagem utilizada nesta dissertação, e que as regras criadas através do algoritmo C4.5 são superiores às que foram criadas através de análise humana das várias estatísticas calculadas para os bytes dos cabeçalhos dos pacotes. Para as comparar, cada conjunto de regras foi utilizado para detetar intrusões em registos de tráfego disponíveis na Internet contendo ataques e em tráfego em tempo real, durante a simulação de ataques. A maioria dos ataques que produz um forte impacto nos cabeçalhos dos pacotes foi detetado por ambos os conjuntos, mas os resultados com os registos retirados da Internet foram melhores para as regras produzidas por aprendizagem automática, dando uma prova clara para o que foi previamente assumido

Caffeic acid loading wound dressing : physicochemical and biological characterization

AIM: Caffeic acid has been described as active against bacteria commonly isolated from wound infections. However, its low stability and poor solubility reduce caffeic acid applicability as a pharmaceutical product. These parameters can be enhanced by complexation with cyclodextrin. The main goal of the present work was to incorporate caffeic acid on cyclodextrin-based hydrogels capable of controlled delivery, in order to be used as antibacterial wound dressing. MATERIALS & METHODS: Cyclodextrin-based hydrogels were prepared by direct crosslinking of -cyclodextrin or hydroxypropyl--cyclodextrin with 1,4-butanediol diglycidyl ether in the presence of hydroxypropyl methylcellulose. RESULTS: The hydrogels obtained combine good physicochemical properties (viscoelasticity, superabsorbency and high ability to retain and deliver caffeic acid) with the preservation of caffeic acid' antibacterial activity and effect on fibroblasts, with gel--cyclodextrin the most suited. CONCLUSION: The hydrogels obtained could be useful as caffeic acid delivery-system devices for the treatment of wound infections.The authors are grateful for the FCT StrategicProject PEst-OE/EQB/LA0023/2013 and the Project 'BioHealth- Biotechnology and Bioengineering approaches to improve healthquality', ref. NORTE-07-0124-FEDER-000027, co-funded by the 'Programa Operacional Regional do Norte' (ON. 2-O Novo Norte), QREN, FEDER. The authors also acknowledge the project 'Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB', ref. FCOMP-01-0124-FEDER-027462. This work is also funded by FEDER funds through the Operational Programme for Competitiveness Factors-COMPETE and National Funds through FCT- Foundation for Science and Technology under the project PEst-C/CTM/UI0264/2011. Additionally, the authors would like to thank the FCT for the grant for E Pinho (SFRH/BD/62665/2009).The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed

A novel bio-inspired microstructure for progressive compressive failure in multidirectional composite laminates

n this study we take inspiration from biological materials to design a modified microstructure for laminated multidirectional (MD) carbon fiber reinforced polymers (CFRP), with the objective of mitigating their compressive failure behavior. We introduce soft inclusions in the form of thin longitudinal strips of foam in 0° load bearing layers, aiming at arresting kinkband propagation. We conceived a bespoke stacking sequence and developed a tailored procedure for manufacturing the microstructure. We then performed in-situ tests on small scale notched specimens from a baseline laminate and a modified one. Results are presented and discussed

Bidirectional mode-locked fiber ring laser

In modern day world, advances in technology are constantly pushing the limits of improvement in measurement accuracy. With each passing year, government agencies and contract companies increase investment in research of high precision, ultra sensitive, instruments. Over the last decade, advancements in ultrashort time scale optics have moved the field of metrology to the quantic realm. At this new scientific frontier, mode-locked lasers, with ultra sensitive phase measurement capabilities, have been playing an increasingly significant role. Among these highly sophisticated systems, mode-locked fiber lasers have been extensively explored in an unidirectional mode, while bidirectional remains a promising source for applications with considerable space for experimental innovation. In this project, efforts have been made to contribute to the scientific achievements in this area, with the implementation of an innovative approach for bidirectional mode-locking of fiber lasers, as a potential source for intra-cavity phase interferometry. It consists of a passively driven active mechanism that both stabilizes the laser and controls the location of the crossing points of the counter-circulating pulses. For that purpose, the idea has been developed in both a theoretical and experimental level, with the design, construction, and testing of a fiber ring laser scheme capable of producing stable and independent (frequency unlocked) bidirectional pulses. In this manuscript, the description of the research is presented in seven separate chapters. The first chapter provides an overview of the project itself, the advantages of the controlling mechanism and the importance and practical applications of bidirectional mode-locked fiber lasers. Chapter two introduces the theoretical background necessary to understand pulse propagation in a nonlinear, birefringent, gain saturated optical fiber. In chapter three, the passive mechanism behind bidirectional mode-locking is detailed. Chapter four deals with the systems modeling and computer simulation, and chapter five explains the functional aspects of the self-regenerative system used to stabilize and control the laser pulsing. Chapter six describes the experimental setup itself, and presents the measured data results. Finally, chapter seven summarizes all the work done, emphasizing the consequences of the experimental findings, and laying out the foundations for future work.\u2