1,367 research outputs found
Testing equivalence of pure quantum states and graph states under SLOCC
A set of necessary and sufficient conditions are derived for the equivalence
of an arbitrary pure state and a graph state on n qubits under stochastic local
operations and classical communication (SLOCC), using the stabilizer formalism.
Because all stabilizer states are equivalent to a graph state by local unitary
transformations, these conditions constitute a classical algorithm for the
determination of SLOCC-equivalence of pure states and stabilizer states. This
algorithm provides a distinct advantage over the direct solution of the
SLOCC-equivalence condition for an unknown invertible local operator S, as it
usually allows for easy detection of states that are not SLOCC-equivalent to
graph states.Comment: 9 pages, to appear in International Journal of Quantum Information;
Minor typos corrected, updated references
Electrodeposition of nanocrystalline Ni-Mo alloys from alkaline glycinate solutions
The induced electrodeposition of nanocrystalline Ni-Mo alloys was investigated using two different molar ratios of Ni:Mo in sodium glycinate solution at pH 9.3. The chemical nature of the Ni2+ and MoO4 2- in alkaline glycinate solution was studied using UV-Vis absorption spectroscopy. The composition of the coating layer was determined using EDX. The crystallinity of electrodeposits was examined using XRD, whereas, the morphology and topography were investigated using SEM and AFM, respectively. The corrosion resistance of Ni-Mo alloys compared to pure Ni was studied in 3.5 % NaCl solution using potentiodynamic polarization and electrochemical impedance techniques. Ni-Mo alloy electrodeposited from the solution containing [MoO4 2-]/[Ni2+] molar ratio of 0.2 show higher corrosion resistance compared to plating solutions of molar ratio 0.1 and pure Ni.NPRP Grant 4-306-2-111 from the Qatar National Research Fund (a Member of The Qatar Foundation).Scopu
A generalized framework unifying image registration and respiratory motion models and incorporating image reconstruction, for partial image data or full images
Surrogate-driven respiratory motion models relate the motion of the internal anatomy to easily acquired respiratory surrogate signals, such as the motion of the skin surface. They are usually built by first using image registration to determine the motion from a number of dynamic images, and then fitting a correspondence model relating the motion to the surrogate signals. In this paper we present a generalized framework that unifies the image registration and correspondence model fitting into a single optimization. This allows the use of 'partial' imaging data, such as individual slices, projections, or k-space data, where it would not be possible to determine the motion from an individual frame of data. Motion compensated image reconstruction can also be incorporated using an iterative approach, so that both the motion and a motion-free image can be estimated from the partial image data. The framework has been applied to real 4DCT, Cine CT, multi-slice CT, and multi-slice MR data, as well as simulated datasets from a computer phantom. This includes the use of a super-resolution reconstruction method for the multi-slice MR data. Good results were obtained for all datasets, including quantitative results for the 4DCT and phantom datasets where the ground truth motion was known or could be estimated
Applying machine learning to automated segmentation of head and neck tumour volumes and organs at risk on radiotherapy planning CT and MRI scans
Radiotherapy is one of the main ways head and neck cancers are treated;
radiation is used to kill cancerous cells and prevent their recurrence.
Complex treatment planning is required to ensure that enough radiation is given
to the tumour, and little to other sensitive structures (known as organs at risk)
such as the eyes and nerves which might otherwise be damaged. This is
especially difficult in the head and neck, where multiple at-risk structures often
lie in extremely close proximity to the tumour. It can take radiotherapy experts
four hours or more to pick out the important areas on planning scans (known as
segmentation).
This research will focus on applying machine learning algorithms to automatic
segmentation of head and neck planning computed tomography (CT) and
magnetic resonance imaging (MRI) scans at University College London
Hospital NHS Foundation Trust patients. Through analysis of the images used
in radiotherapy DeepMind Health will investigate improvements in efficiency of
cancer treatment pathways
Popularity versus Similarity in Growing Networks
Popularity is attractive -- this is the formula underlying preferential
attachment, a popular explanation for the emergence of scaling in growing
networks. If new connections are made preferentially to more popular nodes,
then the resulting distribution of the number of connections that nodes have
follows power laws observed in many real networks. Preferential attachment has
been directly validated for some real networks, including the Internet.
Preferential attachment can also be a consequence of different underlying
processes based on node fitness, ranking, optimization, random walks, or
duplication. Here we show that popularity is just one dimension of
attractiveness. Another dimension is similarity. We develop a framework where
new connections, instead of preferring popular nodes, optimize certain
trade-offs between popularity and similarity. The framework admits a geometric
interpretation, in which popularity preference emerges from local optimization.
As opposed to preferential attachment, the optimization framework accurately
describes large-scale evolution of technological (Internet), social (web of
trust), and biological (E.coli metabolic) networks, predicting the probability
of new links in them with a remarkable precision. The developed framework can
thus be used for predicting new links in evolving networks, and provides a
different perspective on preferential attachment as an emergent phenomenon
Experimental crescentic glomerulonephritis:a new bicongenic rat model
SUMMARY
Crescentic glomerulonephritis (CRGN) is a major cause of human kidney failure, but the underlying mechanisms are not fully understood. Wistar Kyoto (WKY) rats are uniquely susceptible to CRGN following injection of nephrotoxic serum, whereas Lewis (LEW) rats are resistant. Our previous genetic studies of nephrotoxic nephritis (NTN), a form of CRGN induced by nephrotoxic serum, identified Fcgr3 and Jund as WKY genes underlying the two strongest quantitative trait loci for NTN phenotypes: Crgn1 and Crgn2, respectively. We also showed that introgression of WKY Crgn1 or Crgn2 individually into a LEW background did not lead to the formation of glomerular crescents. We have now generated a bicongenic strain, LEW.WCrgn1,2, in which WKY Crgn1 and Crgn2 are both introgressed into the LEW genetic background. These rats show development of NTN phenotypes, including glomerular crescents. Furthermore, we characterised macrophage function and glomerular cytokine profiles in this new strain. Additionally, we show that LEW.WCrgn1,2 rats are resistant to the development of glomerular crescents that is usually induced following immunisation with recombinant rat α3(IV)NC1, the specific Goodpasture autoantigen located in the glomerular basement membrane against which the immune response is directed in experimental autoimmune glomerulonephritis. Our results show that the new bicongenic strain responds differently to two distinct experimental triggers of CRGN. This is the first time that CRGN has been induced on a normally resistant rat genetic background and identifies the LEW.WCrgn1,2 strain as a new, potentially valuable model of macrophage-dependent glomerulonephritis
Altermagnetic lifting of Kramers spin degeneracy
Lifted Kramers spin-degeneracy has been among the central topics of
condensed-matter physics since the dawn of the band theory of solids. It
underpins established practical applications as well as current frontier
research, ranging from magnetic-memory technology to topological quantum
matter. Traditionally, lifted Kramers spin-degeneracy has been considered to
originate from two possible internal symmetry-breaking mechanisms. The first
one refers to time-reversal symmetry breaking by magnetization of ferromagnets,
and tends to be strong due to the non-relativistic exchange-coupling origin.
The second mechanism applies to crystals with broken inversion symmetry, and
tends to be comparatively weaker as it originates from the relativistic
spin-orbit coupling. A recent theory work based on spin-symmetry classification
has identified an unconventional magnetic phase, dubbed altermagnetic, that
allows for lifting the Kramers spin degeneracy without net magnetization and
inversion-symmetry breaking. Here we provide the confirmation using
photoemission spectroscopy and ab initio calculations. We identify two distinct
unconventional mechanisms of lifted Kramers spin degeneracy generated by the
altermagnetic phase of centrosymmetric MnTe with vanishing net magnetization.
Our observation of the altermagnetic lifting of the Kramers spin degeneracy can
have broad consequences in magnetism. It motivates exploration and exploitation
of the unconventional nature of this magnetic phase in an extended family of
materials, ranging from insulators and semiconductors to metals and
superconductors, that have been either identified recently or perceived for
many decades as conventional antiferromagnets
The impact of employee level and work stress on mental health and GP service use: an analysis of a sample of Australian government employees
BACKGROUND: This study sought to identify the extent to which employee level and work stressors were associated with mental health problems experienced by Australian government employees, and with their use of primary care services. METHODS: 806 government employees aged between 40 and 44 years were surveyed as part of an epidemiological study conducted in Australia. Data collected from participants included sociodemographic attributes, physical health, psychological measures and work stressors relating to job control, job demands, job security and skills discretion at work. For 88% of these participants, information on visits made to general practitioners (GPs) for the six months before and after their survey interview was obtained from health insurance records. RESULTS: When work stress and personal factors were taken into account, men at more junior levels reported better mental health, more positive affect and used fewer GP services. Women at middle-management levels obtained less GP care than their more senior counterparts. Both men and women who reported higher levels of work stress were found to have poorer mental health and well-being. The impact of such stressors on GP service use, however, differed for men and women. CONCLUSION: Measures of work stress and not employee level affect the mental health and well-being of government employees. For governments with responsibility for funding health care services, reducing work stress experienced by their own employees offers potential benefits by improving the health of their workforce and reducing outlays for such services
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