Hemodynamic evaluation using four-dimensional flow magnetic resonance imaging for a patient with multichanneled aortic dissection

The hemodynamic function of multichanneled aortic dissection (MCAD) requires close monitoring and effective management to avoid potentially catastrophic sequelae. This report describes a 47-year-old man who underwent endovascular repair based on findings from four-dimensional (4D) flow magnetic resonance imaging of an MCAD. The acquired 4D flow data revealed complex, bidirectional flow patterns in the false lumens and accelerated blood flow in the compressed true lumen. The collapsed abdominal true lumen expanded unsatisfactorily after primary tear repair, which required further remodeling with bare stents. This case study demonstrates that hemodynamic analysis using 4D flow magnetic resonance imaging can help understand the complex pathologic changes of MCAD

On the least common multiple of qq-binomial coefficients

In this paper, we prove the following identity \lcm({n\brack 0}_q,{n\brack 1}_q,...,{n\brack n}_q) =\frac{\lcm([1]_q,[2]_q,...,[n+1]_q)}{[n+1]_q}, where ${n\brack k}_q$ denotes the $q$-binomial coefficient and $[n]_q=\frac{1-q^n}{1-q}$. This result is a $q$-analogue of an identity of Farhi [Amer. Math. Monthly, November (2009)].Comment: 5 page

Metastable helium molecules as tracers in superfluid liquid 4^{4}He

Metastable helium molecules generated in a discharge near a sharp tungsten tip operated in either pulsed mode or continuous field-emission mode in superfluid liquid $^{4}$He are imaged using a laser-induced-fluorescence technique. By pulsing the tip, a small cloud of He$_{2}^{*}$ molecules is produced. At 2.0 K, the molecules in the liquid follow the motion of the normal fluid. We can determine the normal-fluid velocity in a heat-induced counterflow by tracing the position of a single molecule cloud. As we run the tip in continuous field-emission mode, a normal-fluid jet from the tip is generated and molecules are entrained in the jet. A focused 910 nm pump laser pulse is used to drive a small group of molecules to the vibrational $a(1)$ state. Subsequent imaging of the tagged $a(1)$ molecules with an expanded 925 nm probe laser pulse allows us to measure the velocity of the normal fluid. The techniques we developed demonstrate for the first time the ability to trace the normal-fluid component in superfluid helium using angstrom-sized particles.Comment: 4 pages, 7 figures. Submitted to Phys. Rev. Let

Life cycle assessment of white roof and sedum-tray garden roof for office buildings in China

White roof (WR) and Sedum lineare tray garden roof (STGR) have been convinced to improve the energy-efficiency and provide various benefits for conventional impervious grey roofs. Some national and local standards have standardized and recommended these technologies in existing building retrofits, however, they do not include assessment and choice of a particular roof retrofit in different climates. This paper presents a 40-year life-cycle cost analysis (LCCA) of an office building roof retrofitted by adding either WR or STGR over an existing grey roof in five cities, located in four Chinese climate zones. The LCCA find that the WR retrofits exhibit positive life-cycle net savings (NS) in warm winter zones, ranging 5.7–35.1 CNY/m 2 , and STGR retrofits have negative NS of -81.3– -16.7 CNY/m 2 in all climate zones. The NS of both WR and STGR generally tend to improve as one moves from the coldest cities to the warmest cities. LCCA results suggest that adding new building codes concerning crediting or prescribing WR and STGR retrofits into office buildings with grey roofs in hot summer climate zones and warm winter zone in China, respectively. And featured by more specific requirements, the localized Technical Norms help promote the implementation of new building codes

Topological Analysis of Emerging Bipole Clusters Producing Violent Solar Events

During the rising phase of Solar Cycle 24 tremendous activity occurred on the Sun with fast and compact emergence of magnetic flux leading to bursts of flares (C to M and even X-class). We investigate the violent events occurring in the cluster of two active regions (ARs), NOAA numbers 11121 and 11123, observed in November 2010 with instruments onboard the {\it Solar Dynamics Observatory} and from Earth. Within one day the total magnetic flux increased by $70\%$ with the emergence of new groups of bipoles in AR 11123. From all the events on 11 November, we study, in particular, the ones starting at around 07:16 UT in GOES soft X-ray data and the brightenings preceding them. A magnetic-field topological analysis indicates the presence of null points, associated separatrices and quasi-separatrix layers (QSLs) where magnetic reconnection is prone to occur. The presence of null points is confirmed by a linear and a non-linear force-free magnetic-field model. Their locations and general characteristics are similar in both modelling approaches, which supports their robustness. However, in order to explain the full extension of the analysed event brightenings, which are not restricted to the photospheric traces of the null separatrices, we compute the locations of QSLs. Based on this more complete topological analysis, we propose a scenario to explain the origin of a low-energy event preceding a filament eruption, which is accompanied by a two-ribbon flare, and a consecutive confined flare in AR 11123. The results of our topology computation can also explain the locations of flare ribbons in two other events, one preceding and one following the ones at 07:16 UT. Finally, this study provides further examples where flare-ribbon locations can be explained when compared to QSLs and only, partially, when using separatrices.Comment: 42 pages, 15 figure

Predicting Customer Profitability Dynamically over Time: An Experimental Comparative Study

In this paper a comparative study is presented on dynamic prediction of customer profitability over time. Customer profitability is measured by Re-cency, Frequency, and Monetary (RFM) model. A real transactional data set collected from a UK-based retail is examined for the analysis, and a monthly RFM time series for each customer of the business has been generated accord-ingly. At each time point, the customers can be segmented by using k-means clustering into high, medium, or low groups based on their RFM values. 12 dif-ferent models have been utilized to predict how a customer’s membership in terms of profitability group could evolve over time, including regression, multi-layer perception, and Naïve Bayesian models in open-loop and closed-loop modes. The experimental results have demonstrated a good, consistent and in-terpretable predictability of the RFM time series of interest

Quantum Non-Demolition Bell State Measurement and N-party GHZ State Preparation in Quantum Dot

By exploiting the fermionic qubit parity measurement, we present a scheme to realize quantum non-demolition (QND) measurement of Bell-states and generate n-party GHZ state in quantum dot. Compared with the original protocol, the required electron transfer before and after parity measurement can be nonadiabatic, which may speed up the operation speed and make the omitting of spin-orbit interaction more reasonable. This may help us to construct CNOT gate without highly precise control of coupling as the way of D. Gottesman and I. L. Chuang.Comment: some modification to introduction and some details are adde

The cost of uncoupling GB interconnectors

The UK left the EU Integrated Electricity Market on 31/12/20 and with it access to Single Day Ahead Coupling that clears local and cross-border trades jointly – interconnectors are implicitly auctioned. The new the Trade and Cooperation Agreement requires a replacement “Multi-region loose volume coupling” to be introduced before April 2022. Until then, interconnector capacity is allocated by an explicit day ahead auction before the EU auction with nomination after the EU results are known. The paper measures the risks posed by taking positions in each market separately and the resulting costs of uncoupling of GB’s interconnector trade. It compares four forecasts of price differences under two sequencing of markets and explicit auction, determining traders’ risk premia for each. The current timing leads to lower mistakes on the direction of flows, although higher profit volatility, arguing to retain the current timing. Competitive traders locking in their positions after the explicit auction (overstating costs as subsequent trading out of unprofitable positions is ignored) limit the total loss of interconnector revenue from uncoupling to €31 million/yr., and the social cost of uncoupling is €28 million/yr., considerably below earlier estimates in the literature

The Cost of Carbon Leakage: Britain’s Carbon Price Support and Cross-border Electricity Trade

Note - The change in title and this paper replaces CWPE1951.Carbon taxes create global benefits unless offset by increased emissions elsewhere. An additional carbon tax in one country may cause leakage through imports and will also increase costs by creating a wedge between economic marginal costs in different markets, causing an offsetting deadweight loss. We estimate the global benefit, carbon leakage and deadweight cost of the British Carbon Price Support (CPS) on GB’s cross-border electricity trade with France and The Netherlands. Over 2015-2020 the unilateral CPS created €72±20 m/yr deadweight loss, about 31% of the initial economic value created by the interconnector, or 2.5% of the global emissions benefit of the CPS at €2.9±0.1 bn/yr. About 16.3±3.5% of the CO2 emissions reduction is undone by France and The Netherlands, the monetary loss of which is about €584±127 m/yr