Long-distance remote comparison of ultrastable optical frequencies with 1e-15 instability in fractions of a second

We demonstrate a fully optical, long-distance remote comparison of independent ultrastable optical frequencies reaching a short term stability that is superior to any reported remote comparison of optical frequencies. We use two ultrastable lasers, which are separated by a geographical distance of more than 50 km, and compare them via a 73 km long phase-stabilized fiber in a commercial telecommunication network. The remote characterization spans more than one optical octave and reaches a fractional frequency instability between the independent ultrastable laser systems of 3e-15 in 0.1 s. The achieved performance at 100 ms represents an improvement by one order of magnitude to any previously reported remote comparison of optical frequencies and enables future remote dissemination of the stability of 100 mHz linewidth lasers within seconds.Comment: 7 pages, 4 figure

Demonstration of asymmetric electron conduction in pseudosymmetrical photosynthetic reaction centre proteins in an electrical circuit

Photosynthetic reaction centres show promise for biomolecular electronics as nanoscale solar-powered batteries and molecular diodes that are amenable to atomic-level re-engineering. In this work the mechanism of electron conduction across the highly tractable Rhodobacter sphaeroides reaction centre is characterized by conductive atomic force micro-scopy. We find, using engineered proteins of known structure, that only one of the two cofactor wires connecting the positive and negative termini of this reaction centre is capable of conducting unidirectional current under a suitably oriented bias, irrespective of the magnitude of the bias or the applied force at the tunnelling junction. This behaviour, strong functional asymmetry in a largely symmetrical protein–cofactor matrix, recapitulates the strong functional asymmetry characteristic of natural photochemical charge separation, but it is surprising given that the stimulus for electron flow is simply an externally applied bias. Reasons for the electrical resistance displayed by the so-called B-wire of cofactors are explored

Absolute frequency measurement of the magnesium intercombination transition 1S0→3P1^1S_0 \to ^3P_1

We report on a frequency measurement of the $(3s^2)^1S_0\to(3s3p)^3P_1$ clock transition of $^{24}$Mg on a thermal atomic beam. The intercombination transition has been referenced to a portable primary Cs frequency standard with the help of a femtosecond fiber laser frequency comb. The achieved uncertainty is $2.5\times10^{-12}$ which corresponds to an increase in accuracy of six orders of magnitude compared to previous results. The measured frequency value permits the calculation of several other optical transitions from $^1S_0$ to the $^3P_J$-level system for $^{24}$Mg, $^{25}$Mg and $^{26}$Mg. We describe in detail the components of our optical frequency standard like the stabilized spectroscopy laser, the atomic beam apparatus used for Ramsey-Bord\'e interferometry and the frequency comb generator and discuss the uncertainty contributions to our measurement including the first and second order Doppler effect. An upper limit of $3\times10^{-13}$ in one second for the short term instability of our optical frequency standard was determined by comparison with a GPS disciplined quartz oscillator.Comment: 8 pages, 8 figure

Interactions of Bacillus Mojavensis and Fusarium Verticillioides With a Benzoxazolinone (Boa) and Its Transformation Product, Apo

En:Journal of Chemical Ecology (2007, vol. 33, n. 10, p. 1885-1897)The benzoxazolinones, specifically benzoxazolin-2(3H)-one (BOA), are important transformation products of the benzoxazinones that can serve as allelochemicals providing resistance to maize from pathogenic bacteria, fungi, and insects. However, maize pathogens such as Fusarium verticillioides are capable of detoxifying the benzoxazolinones to 2-aminophenol (AP), which is converted to the less toxic N-(2-hydroxyphenyl) malonamic acid (HPMA) and 2-acetamidophenol (HPAA). As biocontrol strategies that utilize a species of endophytic bacterium, Bacillus mojavensis, are considered efficacious as a control of this Fusarium species, the in vitro transformation and effects of BOA on growth of this bacterium was examined relative to its interaction with strains of F. verticillioides. The results showed that a red pigment was produced and accumulated only on BOA-amended media when wild type and the progeny of genetic crosses of F. verticillioides are cultured in the presence of the bacterium. The pigment was identified as 2-amino-3H-phenoxazin-3-one (APO), which is a stable product. The results indicate that the bacterium interacts with the fungus preventing the usual transformation of AP to the nontoxic HPMA, resulting in the accumulation of higher amounts of APO than when the fungus is cultured alone. APO is highly toxic to F. verticillioides and other organisms. Thus, an enhanced biocontrol is suggested by this in vitro study. =580 $aEn:Journal of Chemical Ecolog

Resistance to Wheat streak mosaic virus identified in synthetic wheat lines

Citation: Shoup Rupp, J. L., Simon, Z. G., Gillett-Walker, B., & Fellers, J. P. (2014). Resistance to Wheat streak mosaic virus identified in synthetic wheat lines. Retrieved from http://krex.ksu.eduWheat streak mosaic virus (WSMV) is an important pathogen in wheat that causes significant yield losses each year. WSMV is typically controlled using cultural practices such as the removal of volunteer wheat. Genetic resistance is limited. Until recently, no varieties have been available with major resistance genes to WSMV. Two resistance genes have been derived from Thinopyrum intermedium through chromosome engineering, while a third gene was transferred from bread wheat through classical breeding. New sources of resistance are needed and synthetic wheat lines provide a means of accessing genetic variability in wheat progenitors. A collection of wheat synthetic lines was screened for WSMV resistance. Four lines, 07-SYN-27, -106, -164, and -383 had significant levels of resistance. Resistance was effective at 18 °C and virus accumulation was similar to the resistant control, WGGRC50 containing Wsm1. At 25 °C, resistance was no longer effective and virus accumulation was similar to the susceptible control, Tomahawk

On the mechanism of ubiquinone mediated photocurrent generation by a reaction center based photocathode

Upon photoexcitation, the reaction center (RC) pigment-proteins that facilitate natural photosynthesis achieve a metastable separation of electrical charge among the embedded cofactors. Because of the high quantum efficiency of this process, there is a growing interest in their incorporation into biohybrid materials for solar energy conversion, bioelectronics and biosensing. Multiple bioelectrochemical studies have shown that reaction centers from various photosynthetic organisms can be interfaced with diverse electrode materials for the generation of photocurrents, but many mechanistic aspects of native protein functionality in a non-native environment is unknown. In vivo, RC's catalyse ubiquinone-10 reduction, protonation and exchange with other lipid phase ubiquinone-10s via protein-controlled spatial orientation and protein rearrangement. In contrast, the mechanism of ubiquinone-0 reduction, used to facilitate fast RC turnover in an aqueous photoelectrochemical cell (PEC), may not proceed via the same pathway as the native cofactor. In this report we show truncation of the native isoprene tail results in larger RC turnover rates in a PEC despite the removal of the tail's purported role of ubiquinone headgroup orientation and binding. Through the use of reaction centers with single or double mutations, we also show the extent to which two-electron/two-proton ubiquinone chemistry that operates in vivo also underpins the ubiquinone-0 reduction by surface-adsorbed RCs in a PEC. This reveals that only the ubiquinone headgroup is critical to the fast turnover of the RC in a PEC and provides insight into design principles for the development of new biophotovoltaic cells and biosensors

Resistance to stem rust race TTKS in wheat relative Haynaldia villosa

Tese de doutoramento em Território, Risco e Políticas Públicas, apresentada ao Instituto de Investigação Interdisciplinar da Universidade de CoimbraFor several decades critical infrastructure management belonged to engineering domains; however a new paradigm has emerged - socio-technical paradigm - infrastructures are critical because they have value for society and for a culture. Thus, critical infrastructure operate not only according to technical specifications but also according to constraints imposed by the social environment. The problem is how to integrate in the same model the linkages between infrastructure and social systems. The main goal of this thesis is to propose a new model the Structural Functional Risk Model – SFRM- a model that identifies the roads more vulnerable to interruptions, based on an integrated approach of the structural and functional component of the road network- a critical infrastructure responsible for connecting people, assets and services separated in space. The model is applied to real road network in a multiscalar perspective, the regional context and the municipal context. The case studies are the Central Region of Portugal and Coimbra, a municipality located in this Region. The system used as example focus the road network as element of connection and access between the parishes and the nearest Hospital – a critical infrastructure of the health sector. The methodological approach is composed by three main phases: firstly, the road network is assessed in a structural perspective based on the application of a new approach of the biclustering technique; the following phase is focused on the evaluation of the road network in a functional perspective based on a modified gravity model; the last phase is focused on the integration of structural and functional perspective, which resulted the SFRM. Scenario- based approaches are also relevant in this work, focusing questions such: what can happen? If it does happen, what are the consequences? A scenario-based approach can be a useful support to a more informed, strategic action. Thus, through the work there will be simulated and analyzed road interruption scenarios. The results confirmed the importance of an integrated approach of the structural and functional components. In the assessment of the road network structural component the results pointed that the Biclusters with highest connectivity are mainly located in the II areas economically most dynamic, such the Coastal zone, and the Biclusters with lowest connectivity are mainly located in areas less dynamic, such Beira Transmontana. So, even when the analysis is focused on a network transformed into nodes and edges it is possible to identify relations with the territorial dynamics. The results of the road network functional component assessment point to a significant resources concentration in Coimbra municipality; in the regional context identified significant accessibility gaps across geographical areas and population groups; even in a normal scenario there are significant disparities in terms of accessibility to health care, which can get worse in a road network interruption scenario. From the integration of the structural and functional component of the road network resulted the SFRM, which is a step forward; quantifying the share of accountability of each of the components in the road level of vulnerability. The results demonstrate that territorial constraints play a fundamental role in critical infrastructure management; the strategies set in this domain should take into account the specificities of each territory and population characteristics. This thesis can be seen as step forward in the consolidation of the socio-technical paradigm as well as a tool for the definition of efficient of prevention measures and the definition of strategies aiming quick recovery of the system in case of a disruptive event.Durante várias décadas a gestão das infra-estruturas críticas pertenceu ao domínio da engenharia; contudo surgiu um novo paradigma – o paradigma socio-técnico – as infraestruturas são críticas pelo valor que representam para a sociedade e para a cultura. Neste sentido, o funcionamento das infra-estruturas críticas depende não só de especificidades técnicas, mas também é condicionado pelo meio social. O problema reside em saber como integrar no mesmo modelo as ligações existentes entre as infraestruturas e os sistemas sociais. O principal objetivo deste trabalho é propor um novo modelo - Modelo de Risco Estrutural e Funcional – MREF- que identifica as vias mais vulneráveis a interrupções, numa abordagem integrada da componente estrutural e funcional da rede viária – uma infra-estrutura crítica que tem como função ligar pessoas, bens e serviços separados no espaço. O MRFE é aplicado a uma rede viária real numa perspetiva multiescalar, os casos de estudo são a Região Centro de Portugal e Coimbra, um município localizado nesta Região. O sistema de análise, usado como exemplo, focase na rede viária como elemento de ligação e acesso entre as freguesias e os Hospitais – importantes infra-estruturas críticas do sector da saúde. A metodologia usada neste trabalho é constituída por três fases: numa primeira fase a rede viária é avaliada sob o ponto de vista estrutural com base numa nova abordagem da técnica de biclustering; a fase seguinte foca-se na avaliação da rede viária sob o ponto de vista funcional com base num modelo gravitacional adaptado aos objetivos do presente trabalho; a última fase foca-se na integração da avaliação estrutural com a funcional da qual resulta o MRFE. As abordagens com base em cenários também assumem relevância neste trabalho, focando questões como: O que pode acontecer? Caso aconteça, quais são as consequências? Os resultados desta abordagem contribuem para ação mais informada e estratégica. Neste sentido, ao longo do trabalho serão apresentados e avaliados vários cenários de interrupção de vias. Os resultados demonstram a importância de uma abordagem integrada da componente funcional e da estrutural. Aquando da avaliação da rede viária sob o ponto de vista estrutural os resultados indicaram que os biclusters com maior nível de conectividade se IV encontram essencialmente localizados nas áreas economicamente mais dinâmicas – como a zona costeira, enquanto os biclusters com menor nível de conectividade se encontram essencialmente localizados nas áreas economicamente mais deprimidas – como a Beira Transmontana. Conclui-se que mesmo quando a análise se foca na rede viária enquanto conjunto de nós e ligações é possível identificar relações com a dinâmica territorial. Os resultados da avaliação da rede viária sob o ponto de vista funcional indicam uma significativa polarização de recursos no município de Coimbra, no contexto regional foram identificadas expressivas diferenças em termos de áreas geográficas e grupos populacionais; estas significativas disparidades poderão ser agravadas num cenário de interrupção de vias. O MREF resulta de uma abordagem integrada das componentes estruturais e funcionais da rede viária, um modelo que pode ser visto como um passo em frente uma vez que são definidas e quantificadas as variáveis que influenciam a vulnerabilidade da rede viária. Os resultados demonstram que as condicionantes territoriais devem constituir uma componente fundamental na gestão das infra-estruturas críticas; as estratégias definidas neste âmbito devem ter em atenção as especificidades do território e as características da população. O presente trabalho pode ser visto como contributo para a consolidação do paradigma sociotécnico assim como um instrumento para a definição de medidas de prevenção eficientes e definição de estratégias que tenham em vista o rápido restabelecimento do funcionamento do sistema num cenário disruptivo.Fundação para a Ciência e Tecnologia - SFRH/BD/70952/201

Polychromatic solar energy conversion in pigment-protein chimeras that unite the two kingdoms of (bacterio)chlorophyll-based photosynthesis

Natural photosynthesis can be divided between the chlorophyll-containing plants, algae and cyanobacteria that make up the oxygenic phototrophs and a diversity of bacteriochlorophyll-containing bacteria that make up the anoxygenic phototrophs. Photosynthetic light harvesting and reaction centre proteins from both kingdoms have been exploited for solar energy conversion, solar fuel synthesis and sensing technologies, but the energy harvesting abilities of these devices are limited by each protein’s individual palette of pigments. In this work we demonstrate a range of genetically-encoded, self-assembling photosystems in which recombinant plant light harvesting complexes are covalently locked with reaction centres from a purple photosynthetic bacterium, producing macromolecular chimeras that display mechanisms of polychromatic solar energy harvesting and conversion. Our findings illustrate the power of a synthetic biology approach in which bottom-up construction of photosystems using naturally diverse but mechanistically complementary components can be achieved in a predictable fashion through the encoding of adaptable, plug-and-play covalent interfaces