458 research outputs found

    The influence of pressure on the carbon-oxygen reaction in 0.21 pct. carbon-iron melts subjected to reduced pressures of carbon monoxide

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    The objectives of this investigation were established to be as follows: (1) To study the pressure dependency of the carbon-oxygen reaction in molten carbon-iron-oxygen melts subjected to pressures of less than one atmosphere, and (2) to determine the extent of the melt-crucible reaction by the use of a suitable refractory

    Deterministic generation of entangled photonic cluster states from quantum dot molecules

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    Successful generation of photonic cluster states is the key step in the realization of measurement-based quantum computation and quantum network protocols. Several proposals for the generation of such entangled states from different solid-state emitters have been put forward. Each of these protocols come with their own challenges in terms of both conception and implementation. In this work we propose deterministic generation of these photonic cluster states from a spin-photon interface based on a hole spin qubit hosted in a quantum dot molecule. Our protocol resolves many of the difficulties of existing proposals and paves the way for an experimentally feasible realization of highly entangled multi-qubit photonic states with a high production rate

    Four-dimensional cardiac imaging in living embryos via postacquisition synchronization of nongated slice sequences

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    Being able to acquire, visualize, and analyze 3D time series (4D data) from living embryos makes it possible to understand complex dynamic movements at early stages of embryonic development. Despite recent technological breakthroughs in 2D dynamic imaging, confocal microscopes remain quite slow at capturing optical sections at successive depths. However, when the studied motion is periodic— such as for a beating heart—a way to circumvent this problem is to acquire, successively, sets of 2D+time slice sequences at increasing depths over at least one time period and later rearrange them to recover a 3D+time sequence. In other imaging modalities at macroscopic scales, external gating signals, e.g., an electro-cardiogram, have been used to achieve proper synchronization. Since gating signals are either unavailable or cumbersome to acquire in microscopic organisms, we have developed a procedure to reconstruct volumes based solely on the information contained in the image sequences. The central part of the algorithm is a least-squares minimization of an objective criterion that depends on the similarity between the data from neighboring depths. Owing to a wavelet-based multiresolution approach, our method is robust to common confocal microscopy artifacts. We validate the procedure on both simulated data and in vivo measurements from living zebrafish embryos

    Nonuniform temporal alignment of slice sequences for four-dimensional imaging of cyclically deforming embryonic structures

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    The temporal alignment of nongated slice-sequences acquired at different axial positions in the living embryonic zebrafish heart permits the reconstruction of dynamic, three-dimensional data. This approach overcomes the current acquisition- speed limitation of confocal microscopes for real-time three-dimensional imaging of fast processes. Current synchronization methods align and uniformly scale the data in time, but do not compensate for slight variations in the heart rhythm that occur within a heartbeat. Therefore, they impose constraints on the admissible data quality. Here, we derive a nonuniform registration procedure based on the minimization of the absolute value of the intensity difference between adjacent slice-sequence pairs. The method compensates for temporal intra-sample variations and allows the processing of a wider range of data to build functional, dynamic models of the beating embryonic heart. We show reconstructions from data acquired in living, fluorescent zebrafish embryos

    Constitutive expression of NF-κB inducing kinase in regulatory T cells impairs suppressive function and promotes instability and pro-inflammatory cytokine production

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    CD4+Foxp3+ regulatory T cells (Tregs) are indispensable negative regulators of immune responses. To understand Treg biology in health and disease, it is critical to elucidate factors that affect Treg homeostasis and suppressive function. Tregs express several costimulatory TNF receptor family members that activate non-canonical NF-κB via accumulation of NF-κB inducing kinase (NIK). We previously showed that constitutive NIK expression in all T cells causes fatal multi-organ autoimmunity associated with hyperactive conventional T cell responses and poor Treg-mediated suppression. Here, we show that constitutive NIK expression that is restricted to Tregs via a Cre-inducible transgene causes an autoimmune syndrome. We found that constitutive NIK expression decreased expression of numerous Treg signature genes and microRNAs involved in Treg homeostasis and suppressive phenotype. NIK transgenic Tregs competed poorly with WT Tregs in vivo and produced proinflammatory cytokines upon stimulation. Lineage tracing experiments revealed accumulation of ex- Foxp3+ T cells in mice expressing NIK constitutively in Tregs, and these former Tregs produced copious IFNγ and IL-2. Our data indicate that under inflammatory conditions in which NIK is activated, Tregs may lose suppressive function and may actively contribute to inflammation

    Avoiding leakage and errors caused by unwanted transitions in Lambda systems

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    Three-level Lambda systems appear in various quantum information processing platforms. In several control schemes, the excited level serves as an auxiliary state for implementing gate operations between the lower qubit states. However, extra excited levels give rise to unwanted transitions that cause leakage and other errors, degrading the gate fidelity. We focus on a coherent-population-trapping scheme for gates and design protocols that reduce the effects of the unwanted off-resonant couplings and improve the gate performance up to several orders of magnitude. For a particular setup of unwanted couplings, we find an exact solution, which leads to error-free gate operations via only a static detuning modification. In the general case, we improve gate operations by adding corrective modulations to the pulses, thereby generalizing the DRAG protocol to Lambda systems. Our techniques enable fast and high-fidelity gates and apply to a wide range of optically driven platforms, such as quantum dots, color centers, and trapped ions

    The calculation of the campaign of reactor RITM-200

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    In this paper, the campaign of RITM-200 reactor was calculated. The duration of the campaign was determined taking the net capacity factor into consideration. The calculated duration concurred with the known data. The neutron parameters were calculated using the effective temperature method. The presence of burnable absorber rods was taken into account. Their effect was considered using the diffusional approach. The iterative computations were used to finally determine the temperature of the neutron gas. At the end, the reactivity curve displaying different effects inside fuel, namely fuel and gadolinium burn-out, the poisoning and slagging was drawn
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