Search results for "530"
showing 10 items of 1476 documents
The periodic reporting procedure of the United Nations System and the human right to water: opportunities and challenges
2020
A água é fundamental para a vida. Contudo, foi apenas nos anos 70 que o acesso a este bem começou a ser discutido, a nível internacional, como um direito humano. Antes disso, algumas Convenções e Tratados das Nações Unidas reconheciam, de alguma forma, o direito à água, mas tal direito tinha que ser inferido de outros direitos ou estava limitado à uma determinada categoria de pessoas. Independentemente das suas limitações, estes textos podem reforçar a aplicação do direito humano à água, especialmente através dos seus mecanismos de monitoramento: os relatórios periódicos e os casos litigiosos. Assim, o objetivo deste artigo é analisar em que medida o mecanismo de relatórios periódicos pode …
Asylum Seekers Crisis in Europe 2015: Debating Spaces of Fear and Security in Latvia
2015
Abstract In this paper we analyse emerging discourses of fear on the one hand and safety and security on the other. In the context of rupture - sudden, unprecedented asylum flows as well as the historical context of the fear and experience of losing the state’s freedom, we pose the following research question: Where do insecurities and fear come from and how are spaces of security and safety carved out through public discourses? We argue that, instead of singling out political discourses in Eastern European as filled with hatred towards other ethnicities and races or an inability to show solidarity with human suffering, we have to open up a far more deep reaching debate on the interplay of …
Search for the Lepton Flavor Violation Process J/ψ→eμ at BESIII
2013
We search for the lepton-flavor-violating decay of the $J/\psi$ into an electron and a muon using $(225.3\pm2.8)\times 10^{6}$ $J/\psi$ events collected with the BESIII detector at the BEPCII collider. Four candidate events are found in the signal region, consistent with background expectations. An upper limit on the branching fraction of $\mathcal{B}(J/\psi \to e\mu)< 1.5 \times 10^{-7}$ (90% C.L.) is obtained.
Dephasing due to quasiparticle tunneling in fluxonium qubits: a phenomenological approach
2015
The fluxonium qubit has arisen as one of the most promising candidate devices for implementing quantum information in superconducting devices, since it is both insensitive to charge noise (like flux qubits) and insensitive to flux noise (like charge qubits). Here, we investigate the stability of the quantum information to quasiparticle tunneling through a Josephson junction. Microscopically, this dephasing is due to the dependence of the quasiparticle transmission probability on the qubit state. We argue that on a phenomenological level the dephasing mechanism can be understood as originating from heat currents, which are flowing in the device due to possible effective temperature gradients…
Nonlinear relaxation phenomena in metastable condensed matter systems
2016
Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced s…
Tunneling and point contact investigations of La1.85Sr0.15CuO4
1987
The high-T c superconductor La1.85Sr0.15CuO4 was investigated by means of point contact and tunneling measurements on small-sized contacts. We find different values for the energy gap at different points of the samples. The ratio 2Delta/k B T c ranges from about 3 to 6. For some point contacts we observe a clear signature of a supercurrent. Data for the temperature dependence of the critical current are presented.
Unraveling the LiNbO3 X-cut surface by atomic force microscopy and density functional theory
2014
The ${\text{LiNbO}}_{3}$(2$\overline{1}\overline{1}0$) surface, commonly referred to as X-cut, is investigated by means of atomic force microscopy and first-principles calculations. Atomically resolved atomic force microscopy images show geometrical patterns not compatible with truncated bulk terminations. Fast Fourier transformation of the real-space images shows an oblique surface unit cell with lattice parameters of $a=0.75\ifmmode\pm\else\textpm\fi{}0.02$ nm, $b=0.54\ifmmode\pm\else\textpm\fi{}0.02$ nm, and $\ensuremath{\alpha}=94.{8}^{\ensuremath{\circ}}$. Comparing these experimental results with the theoretical models of stable surface terminations provides clear evidence for the for…
Single-molecule switching with non-contact atomic force microscopy
2011
We report upon controlled switching of a single 3,4,9,10-perylene tetracarboxylic diimide derivative molecule on a rutile TiO(2)(110) surface using a non-contact atomic force microscope at room temperature. After submonolayer deposition, the molecules adsorb tilted on the bridging oxygen row. Individual molecules can be manipulated by the atomic force microscope tip in a well-controlled manner. The molecules are switched from one side of the row to the other using a simple approach, taking benefit of the sample tilt and the topography of the titania substrate. From density functional theory investigations we obtain the adsorption energies of different positions of the molecule. These adsorp…
Three-dimensional atomic force microscopy mapping at the solid-liquid interface with fast and flexible data acquisition
2016
We present the implementation of a three-dimensional mapping routine for probing solid-liquid interfaces using frequency modulation atomic force microscopy. Our implementation enables fast and flexible data acquisition of up to 20 channels simultaneously. The acquired data can be directly synchronized with commercial atomic force microscope controllers, making our routine easily extendable for related techniques that require additional data channels, e.g., Kelvin probe force microscopy. Moreover, the closest approach of the tip to the sample is limited by a user-defined threshold, providing the possibility to prevent potential damage to the tip. The performance of our setup is demonstrated …
Dendrimer-coated magnetic particles for radionuclide separation
2005
Magnetic particles were synthesised for radionuclide removal from nuclear wastes by magnetic separation. Dendrimers with terminal amino groups attached to the particle surface were used to bind chelating groups for lanthanides and actinides. This led to a 50–400-fold increase of the distribution coefficients for europium and americium in comparison to the reference particles without the dendrimers. Back-extraction studies have demonstrated the possibility of multiple particle recycling.