238 research outputs found
Optimal state for keeping reference frames aligned and the Platonic solids
The optimal N qubit states featuring highest sensitivity to small
misalignment of cartesian reference frames are found using the Quantum
Cramer-Rao bound. It is shown that the optimal states are supported on the
symmetric subspace and hence are mathematically equivalent to a single spin
J=N/2. Majorana representation of spin states is used to reveal a beautiful
connection between the states optimal for aligning reference frames and the
platonic solids
Quantum phase estimation with lossy interferometers
We give a detailed discussion of optimal quantum states for optical two-mode
interferometry in the presence of photon losses. We derive analytical formulae
for the precision of phase estimation obtainable using quantum states of light
with a definite photon number and prove that maximization of the precision is a
convex optimization problem. The corresponding optimal precision, i.e. the
lowest possible uncertainty, is shown to beat the standard quantum limit thus
outperforming classical interferometry. Furthermore, we discuss more general
inputs: states with indefinite photon number and states with photons
distributed between distinguishable time bins. We prove that neither of these
is helpful in improving phase estimation precision.Comment: 12 pages, 5 figure
Optimal Quantum Phase Estimation
By using a systematic optimization approach we determine quantum states of
light with definite photon number leading to the best possible precision in
optical two mode interferometry. Our treatment takes into account the
experimentally relevant situation of photon losses. Our results thus reveal the
benchmark for precision in optical interferometry. Although this boundary is
generally worse than the Heisenberg limit, we show that the obtained precision
beats the standard quantum limit thus leading to a significant improvement
compared to classical interferometers. We furthermore discuss alternative
states and strategies to the optimized states which are easier to generate at
the cost of only slightly lower precision.Comment: 4 pages, 4 figures. Replaced with final versio
Photocatalytic activity of nanostructured anatase coatings obtained by cold gas spray
This article describes a photocatalytic nanostructured anatase coating deposited by cold gas spray (CGS)supported on titanium sub-oxide (TiO22x) coatings obtained by atmospheric plasma spray (APS) onto stainless steel cylinders. The photocatalytic coating was homogeneous and preserved the composition and nanostructure of the starting powder. The inner titanium sub-oxide coating favored the deposition of anatase particles in the solid state. Agglomerated nano-TiO2 particles fragmented when impacting onto the hard surface of the APS TiO22x bond coat. The rough surface provided by APS provided an ideal scenario for entrapping the nanostructured particles, which may be adhered onto the bond coat due to chemical bonding; a possible bonding mechanism is described. Photocatalytic experiments showed that CGS nano-TiO2 coating was active for photodegrading phenol and formic acid under aqueous conditions. The results were similar to the performance obtained by competitor technologies and materials such as dip-coating P25 photocatalysts. Disparity in the final performance of the photoactive materials may have been caused by differences in grain size and the crystalline composition of titanium dioxide
Minor and potentially toxic trace elements in milk and blood serum of dairy donkeys
The aim of this trial was to study the concentration of Ti, V, As, Rb, Sr, Mo, Cd, Cs, and Pb in donkey milk and blood serum. One hundred twelve individual milk and blood serum samples were collected from 16 lactating donkeys (Martina-Franca-derived population; 6 to 12 yr old; 3 to 7 parities; average live weight 205.4kg; 32 to 58 d after foaling at the beginning of the trial) during a 3-mo-long experiment. The samples were analyzed for the aforementioned elements by inductively coupled plasma-mass spectrometry. Feedstuff and drinking water were also analyzed for the investigated elements. Data were processed by ANOVA for repeated measures. Average milk concentrations (±SD) of Ti, Rb, Sr, Mo, Cs, and Pb were 77.3 (±7.7), 339.1 (±82.1), 881.7 (±270.4), 4.5 (±1.6), 0.49 (±0.09), and 3.2 (±2.7) μg/L, respectively. More than 80% of samples were below the limit of detection for V, As, and Cd in milk and for Cd, and Pb in blood serum. The lower bound calculated for milk V, As, and Cd was 0.03μg/L for the 3 elements, the upper bound was calculated at 0.23, 0.10, and 0.31μg/L and the maximum value was observed at 0.54, 0.15, and 0.51μg/L, respectively. The average milk concentrations of Ti, Rb, Sr, Mo, and Cs were 600, 458, 346, 16, and 294%, respectively, than those of blood serum. Yet, Cs concentrations were in the same order of magnitude in milk and serum. Moderate to strong positive and significant correlation coefficients were observed between milk and blood serum concentrations for Ti, Rb, Sr, and Cs. The effect of the stage of lactation was significant for all the investigated elements in milk and blood serum, but most of the elements showed only small changes or inconsistent trends, and only the concentrations of Rb and Sr showed decreasing trends both in milk and blood serum. The relationship between milk and blood serum element concentrations indicates that the mammary gland plays a role in determining the milk concentrations of Mo, Ti, Rb, Sr, Mo, and Cs. In the current experimental conditions, in agreement with the low levels in drinking water and feedstuff, donkey milk concentration of potentially toxic elements was very low and did not raise health concerns for human consumption
The elusive Heisenberg limit in quantum enhanced metrology
We provide efficient and intuitive tools for deriving bounds on achievable
precision in quantum enhanced metrology based on the geometry of quantum
channels and semi-definite programming. We show that when decoherence is taken
into account, the maximal possible quantum enhancement amounts generically to a
constant factor rather than quadratic improvement. We apply these tools to
derive bounds for models of decoherence relevant for metrological applications
including: dephasing,depolarization, spontaneous emission and photon loss.Comment: 10 pages, 4 figures, presentation imporved, implementation of the
semi-definite program finding the precision bounds adde
Non-Canonical NF-κB Activation and Abnormal B Cell Accumulation in Mice Expressing Ubiquitin Protein Ligase-Inactive c-IAP2
Loss of c-IAP2 ubiquitin ligase activity, which occurs in the lymphoma-causing c-IAP2/MALT1 fusion protein, activates non-canonical NF-κB signaling and results in B cell abnormalities characteristic of MALT lymphoma
The NF-κB and IκB proteins: New discoveries and insights
The transcription factor NF-κB has attracted widespread attention among researchers in many fields based on the following: its unusual and rapid regulation, the wide range of genes that it controls, its central role in immunological processes, the complexity of its subunits, and its apparent involvement in several diseases. A primary level of control for NF-κB is through interactions with an inhibitor protein called IκB. Recent evidence confirms the existence of multiple forms of IκB that appear to regulate NF-κB by distinct mechanisms. NF-κB can be activated by exposure of cells to LPS or inflammatory cytokines such as TNF or IL-1, viral infection or expression of certain viral gene products, UV irradiation, B or T cell activation, and by other physiological and nonphysiological stimuli. Activation of NF-κB to move into the nucleus is controlled by the targeted phosphorylation and subsequent degradation of IκB. Exciting new research has elaborated several important and unexpected findings that explain mechanisms involved in the activation of NF-κB. In the nucleus, NF-κB dimers bind to target DNA elements and activate transcription of genes encoding proteins involved with immune or inflammation responses and with cell growth control. Recent data provide evidence that NF-κB is constitutively active in several cell types, potentially playing unexpected roles in regulation of gene expression. In addition to advances in describing the mechanisms of NF-κB activation, excitement in NF-κB research has been generated by the first report of a crystal structure for one form of NF-κB, the first gene knockout studies for different forms of NF-κB and of IκB, and the implications for therapies of diseases thought to involve the inappropriate activation of NF-κB
Charting the NF-κB Pathway Interactome Map
Inflammation is part of a complex physiological response to harmful stimuli and pathogenic stress. The five components of the Nuclear Factor κB (NF-κB) family are prominent mediators of inflammation, acting as key transcriptional regulators of hundreds of genes. Several signaling pathways activated by diverse stimuli converge on NF-κB activation, resulting in a regulatory system characterized by high complexity. It is increasingly recognized that the number of components that impinges upon phenotypic outcomes of signal transduction pathways may be higher than those taken into consideration from canonical pathway representations. Scope of the present analysis is to provide a wider, systemic picture of the NF-κB signaling system. Data from different sources such as literature, functional enrichment web resources, protein-protein interaction and pathway databases have been gathered, curated, integrated and analyzed in order to reconstruct a single, comprehensive picture of the proteins that interact with, and participate to the NF-κB activation system. Such a reconstruction shows that the NF-κB interactome is substantially different in quantity and quality of components with respect to canonical representations. The analysis highlights that several neglected but topologically central proteins may play a role in the activation of NF-κB mediated responses. Moreover the interactome structure fits with the characteristics of a bow tie architecture. This interactome is intended as an open network resource available for further development, refinement and analysis
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