Analysis of the entanglement between two individual atoms using global Raman rotations

Making use of the Rydberg blockade, we generate entanglement between two atoms individually trapped in two optical tweezers. In this paper we detail the analysis of the data and show that we can determine the amount of entanglement between the atoms in the presence of atom losses during the entangling sequence. Our model takes into account states outside the qubit basis and allows us to perform a partial reconstruction of the density matrix describing the two atom state. With this method we extract the amount of entanglement between pairs of atoms still trapped after the entangling sequence and measure the fidelity with respect to the expected Bell state. We find a fidelity $F_{\rm pairs} =0.74(7)$ for the 62% of atom pairs remaining in the traps at the end of the entangling sequence

Ajuda Humanitária em Conflitos Armados: o caso do cerco de Aleppo

O presente artigo objetiva examinar como se configurou a Ajuda Humanitária em Aleppo no ano de 2016, no contexto da guerra civil síria. O conflito na Síria começou com manifestações pacíficas contra o governo de Bashar Al-Assad e transformou-se em uma Guerra Civil em 2011. Devido à grande presença da resistência ao regime de Bashar Al-Assad estar concentrada na cidade de Aleppo, os embates resultaram em uma séria crise humanitária, aspecto que é o foco deste trabalho. Metodologicamente a pesquisa é uma análise exploratória, fundamentando-se em fontes documentais das organizações humanitárias que são trianguladas com a bibliografia especializada e análises de think-tanks. O artigo inicialmente busca abordar o conceito e discussão sobre Ajuda Humanitária, seus atores e ações. Em seguida, apresenta uma contextualização do conflito sírio e da Batalha de Aleppo. Por fim, examina a assistência realizada em Aleppo por três organizações Cruz Vermelha (em parceria com o Crescente Vermelho Árabe Sírio), os Médicos sem Fronteiras e os Capacetes Brancos. A investigação demonstrou que a ajuda humanitária foi realizada, apesar do intenso conflito na região, e que os atores humanitários buscaram garantir as necessidades básicas para os que permaneceram no país

Engineering Genetically Encoded Nanosensors for Real-Time In Vivo Measurements of Citrate Concentrations

Citrate is an intermediate in catabolic as well as biosynthetic pathways and is an important regulatory molecule in the control of glycolysis and lipid metabolism. Mass spectrometric and NMR based metabolomics allow measuring citrate concentrations, but only with limited spatial and temporal resolution. Methods are so far lacking to monitor citrate levels in real-time in-vivo. Here, we present a series of genetically encoded citrate sensors based on Förster resonance energy transfer (FRET). We screened databases for citrate-binding proteins and tested three candidates in vitro. The citrate binding domain of the Klebsiella pneumoniae histidine sensor kinase CitA, inserted between the FRET pair Venus/CFP, yielded a sensor highly specific for citrate. We optimized the peptide linkers to achieve maximal FRET change upon citrate binding. By modifying residues in the citrate binding pocket, we were able to construct seven sensors with different affinities spanning a concentration range of three orders of magnitude without losing specificity. In a first in vivo application we show that E. coli maintains the capacity to take up glucose or acetate within seconds even after long-term starvation

G-protein signaling: back to the future

Heterotrimeric G-proteins are intracellular partners of G-protein-coupled receptors (GPCRs). GPCRs act on inactive Gα·GDP/Gβγ heterotrimers to promote GDP release and GTP binding, resulting in liberation of Gα from Gβγ. Gα·GTP and Gβγ target effectors including adenylyl cyclases, phospholipases and ion channels. Signaling is terminated by intrinsic GTPase activity of Gα and heterotrimer reformation — a cycle accelerated by ‘regulators of G-protein signaling’ (RGS proteins). Recent studies have identified several unconventional G-protein signaling pathways that diverge from this standard model. Whereas phospholipase C (PLC) β is activated by Gαq and Gβγ, novel PLC isoforms are regulated by both heterotrimeric and Ras-superfamily G-proteins. An Arabidopsis protein has been discovered containing both GPCR and RGS domains within the same protein. Most surprisingly, a receptor-independent Gα nucleotide cycle that regulates cell division has been delineated in both Caenorhabditis elegans and Drosophila melanogaster. Here, we revisit classical heterotrimeric G-protein signaling and explore these new, non-canonical G-protein signaling pathways

Rússia e a Guerra Civil Síria: o posicionamento russo no Conselho de Segurança das Nações Unidas

The present work analyzes the position of Russia in the United Nations Security Council (UNSC) during the Syrian Civil War. The latter began in 2011 and continues to the present day. The conflict generates several deaths, displacements and a humanitarian crisis that needs a resolution. In this scenario, a position from the UNSC and actions to resolve the case are expected. However, a lack of consensus among UNSC members and Russia played a central role, as it participated in the conflict in 2015, supported Bashar al-Assad and vetoed some resolution proposals on the conflict. For this important role, we seek to explore possible Russian motivations and interests that led to the lack of consensus in the UNSC regarding the Syrian conflict. Therefore, we present the Syrian conflict and its actors; then we discuss Russian foreign policy and its interests; finally, we explore the Russian position in the UNSC during the conflict. As a methodological basis, we start from an exploratory-descriptive analysis with data collection and documentary research based on the UNSC resolutions in the years 2012-2020. In conclusion, we emphasize that Syria is a central part of Russian foreign policy, with economic and strategic dimensions that overcome the civil conflict.O trabalho analisa o posicionamento da Rússia no Conselho de Segurança da ONU durante a Guerra Civil Síria. Nesse cenário, é esperado um posicionamento do CSNU e ações para solucionar o caso. Há uma falta de consenso entre os membros do CSNU e a Rússia teve papel central, pois participou do conflito em 2015 e apoia Bashar al-Assad. Por esse papel importante, buscamos explorar as possíveis motivações e interesses russos que levaram à falta de consenso no CSNU em relação ao conflito sírio à luz de uma leitura realismo ofensivo. Inicialmente apresentamos o conflito sírio e os seus atores; em seguida, abordamos a política externa russa e seus interesses; por fim, exploramos o posicionamento russo no CSNU durante o conflito. Como base metodológica, partimos de uma análise exploratória-descritiva com coleta de dados e pesquisa documental fundamentada nas resoluções do CSNU nos anos de 2012-2020. Em conclusão, destacamos que a Síria é parte central da política externa russa, com dimensões econômicas e estratégicas que ultrapassam a questão do conflito. Enquanto a Rússia continua a proteger um de seus aliados na região a Síria recebe por sua vez o apoio político e diplomático para suas ações no cenário internacional

Measuring dynamic changes in cAMP using fluorescence resonance energy transfer.

cAMP is a ubiquitous second messenger that controls numerous cellular events including movement, growth, metabolism, contraction, and synaptic plasticity. With the emerging concept of compartmentalization of cAMP-dependent signaling, a detailed study of the spatio-temporal intracellular dynamics of cAMP is required. Here we describe a new methodology for monitoring fluctuations of cAMP in living cells, based on the use of a genetically encoded biosensor. The regulatory and catalytic subunits of the main cAMP effector, the protein kinase A (PKA), fused with two suitable green fluorescent protein (GFP) mutants is used for measuring changes in fluorescence resonance energy transfer (FRET) that correlate with changes in intracellular cAMP levels. This method allows the study of cAMP fluctuations in living cells with high resolution both in time and in space

Study of cyclic adenosine monophosphate microdomains in cells.

Cyclic adenosine monophosphate (cAMP) controls the physiological response to many diverse extracellular stimuli. To maintain signal specificity, cAMP-mediated signaling is finely tuned by means of a complex array of proteins that control the spatial and temporal dynamics of the second messenger within the cell. To unravel the way a cell encodes cAMP signals, new biosensors have recently been introduced that allow imaging of the second messenger in living cells with high spatial resolution. The more recent generation of such biosensors exploits the phenomenon of fluorescence resonance energy transfer between the green fluorescent protein- tagged subunits of a chimeric protein kinase A, as the way to visualize and measure the dynamic fluctuations of cAMP. This chapter describes the molecular basis on which such a genetically encoded cAMP sensor relies and the tools and methods required to perform cAMP measurements in living samples

A Distributed Query Execution Engine in a Grid Environment

Grid is a computational environment in which applica-tions can use multiple distributed computational resources in a safe, coordinated, efficient and transparent way. Data Integration Middleware Systems (DIMS) are originally dis-tributed systems that can make use of Grid environments to obtain a better performance and a rational use of available resources. This work describes a Distributed Query Exe-cution Engine (DQEE) inserted in a Grid environment for executing sub-queries and operators in a distributed and parallel way. We present an approach to obtain an efficient distributed query execution with a reduced response time by the use of the DQEE. 1 1