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The manipulation of spins in a solid-state system — nitrogen–vacancy defects in diamond — allows the experimental realization of a universal set of geometric quantum gates using holonomies, that is, non-Abelian generalizations of the Berry phase, and offers a scalable platform with the potential for room-temperature quantum computing. New angles on quantum computers One obstacle to the development of practical quantum computers is the perceived need for substantial error-correction schemes. Such schemes, however, would slow down the computation process and negate some of the potential advantages of quantum technology. An alternative approach would be to use inherently fault-tolerant quantum computing principles that are robust to noise, such as that due to protection from geometric rules. Some all-geometric quantum computation experiments have been reported but the challenge is to find a platform that is scalable. Luming Duan and colleagues now report the experimental realization of a universal set of geometric quantum gates with spins residing in diamond defect centres. Although the experiments are based on two qubits in one diamond centre, the work offers a promising direction to all-geometric, robust quantum computation in the solid state and at room temperature. Experimental realization of a universal set of quantum logic gates is the central requirement for the implementation of a quantum computer. In an ‘all-geometric’ approach to quantum computation 1 , 2 , the quantum gates are implemented using Berry phases 3 and their non-Abelian extensions, holonomies 4 , from geometric transformation of quantum states in the Hilbert space 5 . Apart from its fundamental interest and rich mathematical structure, the geometric approach has some built-in noise-resilience features 1 , 2 , 6 , 7 . On the experimental side, geometric phases and holonomies have been observed in thermal ensembles of liquid molecules using nuclear magnetic resonance 8 , 9 ; however, such systems are known to be non-scalable for the purposes of quantum computing 10 . There are proposals to implement geometric quantum computation in scalable experimental platforms such as trapped ions 11 , superconducting quantum bits 12 and quantum dots 13 , and a recent experiment has realized geometric single-bit gates in a superconducting system 14 . Here we report the experimental realization of a universal set of geometric quantum gates using the solid-state spins of diamond nitrogen–vacancy centres. These diamond defects provide a scalable experimental platform 15 , 16 , 17 with the potential for room-temperature quantum computing 16 , 17 , 18 , 19 , which has attracted strong interest in recent years 20 . Our experiment shows that all-geometric and potentially robust quantum computation can be realized with solid-state spin quantum bits, making use of recent advances in the coherent control of this system 15 , 16 , 17 , 18 , 19 , 20 .

This study evaluated the effects of rumen-protected folic acid (RPFA) and betaine (BT) on growth performance, nutrient digestion and blood metabolites in bulls. Forty-eight Angus bulls were blocked by body weight and randomly assigned to four treatments in a 2 × 2 factorial design. BT of 0 or 0·6 g/kg DM was supplemented to diet without or with the addition of 6 mg/kg DM of folic acid from RPFA, respectively. Average daily gain increased by 25·2 and 6·29 % for addition of BT without RPFA and with RPFA, respectively. Digestibility and ruminal total volatile fatty acids of neutral-detergent fibre and acid-detergent fibre increased, feed conversion ratio and blood folate decreased with the addition of BT without RPFA, but these parameters were unchanged with BT addition in diet with RPFA. Digestibility of DM, organic matter and crude protein as well as acetate:propionate ratio increased with RPFA or BT addition. Ruminal ammonia-N decreased with RPFA addition. Activity of carboxymethyl cellulase, cellobiase, xylanase, pectinase and protease as well as population of total bacteria, protozoa, Fibrobacter succinogenes and Ruminobacter amylophilus increased with RPFA or BT addition. Laccase activity and total fungi, Ruminococcus flavefaciens and Prevotella ruminicola population increased with RPFA addition, whereas Ruminococcus albus population increased with BT addition. Blood glucose, total protein, albumin, growth hormone and insulin-like growth factor-1 increased with RPFA addition. Addition of RPFA or BT decreased blood homocysteine. The results indicated that addition of BT stimulated growth and nutrient digestion in bulls only when RPFA was not supplemented.

Active control of a turbulent boundary layer has been experimentally investigated with a view to reducing the skin-friction drag and gaining some insight into the mechanism that leads to drag reduction. A spanwise-aligned array of piezo-ceramic actuators was employed to generate a transverse travelling wave along the wall surface, with a specified phase shift between adjacent actuators. Local skin-friction drag exhibits a strong dependence on control parameters, including the wavelength, amplitude and frequency of the oscillation. A maximum drag reduction of 50 % has been achieved at 17 wall units downstream of the actuators. The near-wall flow structure under control, measured using smoke–wire flow visualization, hot-wire and particle image velocimetry techniques, is compared with that without control. The data have been carefully analysed using techniques such as streak detection, power spectra and conditional averaging based on the variable-interval time-average detection. All the results point to a pronounced change in the organization of the perturbed boundary layer. It is proposed that the actuation-induced wave generates a layer of highly regularized streamwise vortices, which acts as a barrier between the large-scale coherent structures and the wall, thus interfering with the turbulence production cycle and contributing partially to the drag reduction. Associated with the generation of regularized vortices is a significant increase, in the near-wall region, of the mean energy dissipation rate, as inferred from a substantial decrease in the Taylor microscale. This increase also contributes to the drag reduction. The scaling of the drag reduction is also examined empirically, providing valuable insight into the active control of drag reduction.

Three-dimensional polydimethylsiloxane platforms were developed to mimic the extracellular matrix with blood vessels by having scaffolds with micropatterns, porous membrane and trenches. Precisely controlled physical dimensions, layouts, and topography as well as different surface chemical treatments were applied to study their influences on nasopharyngeal carcinoma cell (10-15 [mu]m in diameter) migration in mimicked platforms over 15-hour of time-lapse imaging. By placing the pores at different distance from the edges of the trenches, pores with different trench sidewall exposures and effective sizes were generated. Pores right next to the trench sidewalls showed the highest cell traversing probability, most likely related to the larger surface contact area with cells along the sidewalls. Straight grating oriented perpendicular to trenches below the top layer increased cell traversing probability. Pore shape as well as pore size influenced the cell traversing probability and cells could not traverse through pores that were 6 [mu]m or less in diameter, which is much smaller than the cell size. Trench depth of 15 [mu]m could induce more cells to traverse through the porous membrane, while shallower trenches impeded cell traversing and longer time was needed for cells to traverse because 3 and 6 [mu]m deep trenches were much smaller than cell size which required large cell deformation. Hydrophobic surface coating on the top layer and fibronectin in pores and trenches increased the cell traversing probability and reduced the pore size that cells could traverse from 8 to 6 [mu]m, which indicated that cells could have larger deformation with certain surface coatings.

Whereas chronological age (CA) cannot distinguish functional differences among individuals of the same age, the biological age (BA) may be used to reflect the functional state of the body. The purpose of this study was to construct an integral formula of the BA, by using principle component analysis (PCA). The vital organ function of 505 healthy individuals of Han origin (age 35–91 years) was examined. A total of 114 indicators of cardiovascular, pulmonary, and brain functions, and clinical, inflammatory, genetic, psychological, and life habit factors were assessed as candidate indicators of aging. Candidate indicators were submitted with CA to correlation and redundancy analyses. The PCA method was used to build an integral formula of the BA for the population. Seven biomarkers were selected in accordance with a certain load standard. These biomarkers included the trail making test (TMT), pulse pressure (PP), mitral valve annulus ventricular septum of the peak velocity of early filling (MVES), minimum carotid artery intimalmedial thickness (IMTmin), maximum internal diameter of the carotid artery (Dmax), maximal midexpiratory flow rate 75/25 (MMEF75/25), and Cystatin C (CysC). The formula for the BA was: BA = 0.0685 (TMT) + 0.267 (PP)–1.375 (MVES) + 22.443 (IMTmin) + 2.962 (Dmax)–2.332 (MMEF75/25) + 16.104 (CysC) + 0.137 (CA) + 0.492. Several genetic and lifestyle indicators were considered as candidate markers of aging. However, ultimately, only markers reflecting the function of the vital organs were included in the BA formula. This study represents a useful attempt to employ multiple indicators to build a comprehensive BA evaluation formula of aging populations.

Systematic investigation with large sample size of the distribution of etiologies of renal artery stenosis (RAS) is scant in both Western countries and China. We retrospectively analyzed the etiology of RAS in 2047 consecutive inpatients diagnosed with RAS for hypertension at Fuwai Hospital between 1999 and 2014. The number of patients with atherosclerosis was 1668 (81.5%), 259 (12.7%) with Takayasu’s arteritis (TA), 86 (4.2%) with fibromuscular dysplasia (FMD), 34 (1.6%) with other causes. There was an obvious increase with age in the proportion of atherosclerotic RAS ( P <0.001). In patients aged ⩽40 years ( n =319) the predominant etiology of RAS was TA (60.5%), followed by FMD (24.8%). In patients aged >40 years ( n =1728) the major cause of RAS was atherosclerosis (94.7%), followed by TA (3.8%).The proportion of TA and FMD in female patients was significantly higher than that in male patients ( P <0.001). In female patients aged ⩽40 years ( n =215), the top three etiologies of RAS were TA (68.4%), FMD (27.9%) and atherosclerosis (1.4%). The present analysis showed that atherosclerosis, TA and FMD were sequentially the top three causes of RAS in the National Center of China. Age and gender had a significant effect on the distribution of etiologies of RAS.

Background Psoriasis is a common chronic inflammatory disease caused by excessive activation of CD4+T cells, including Th17, Th1 and Th22. The role of CD8+T cells in psoriasis pathogenesis remains poorly understood. Aim To identify the phenotype of CD8+T cells in patients with psoriasis and to investigate its role in the formation of lesions. Methods The phenotype of CD8+T cells in psoriatic lesions was detected by immunofluorescence staining. Flow cytometry was performed to detect their phenotype in peripheral blood. Thereafter, coculture of CD8αα+T cells with autogenous CD4+T cells was performed to investigate the function of CD8αα+T cells in patients with psoriasis. Finally, pro‐inflammatory factors produced by CD8αα+T cells were examined by immunofluorescence staining and flow cytometry. Results Compared to the CD8αβ+T cells, CD8αα+T cell infiltration in psoriatic lesions markedly increased. Moreover, epidermal CD8αα+T cells exhibited tissue‐resident memory T cells (TRM) phenotypes and dermal CD8αα+T cells exhibited effector memory (TEM) phenotypes in psoriatic lesions. Additionally, we found that CD8αα+T cells from patients with psoriasis did not express the markers of regulatory T cells and could promote the proliferation of CD4+T effector cells and produce interleukin‐17 and interferon‐γ. Conclusions Our findings demonstrate that CD8αα+T cells contribute to the pathogenesis of psoriasis by producing pro‐inflammatory factors. We identified a new subset of CD8+T cells, CD8αα+TRM cells, which contribute to psoriasis by producing pro‐inflammatory cytokines.

As a way to circumvent the quantum no-cloning theorem, approximate quantum cloning protocols have received wide attention with remarkable applications. Copying of quantum states to memory qubits provides an important strategy for eavesdropping in quantum cryptography. We report an experiment that realizes cloning of quantum states from an electron spin to a nuclear spin in a hybrid solid-state spin register with near-optimal fidelity. The nuclear spin provides an ideal memory qubit at room temperature, which stores the cloned quantum states for a millisecond under ambient conditions, exceeding the lifetime of the original quantum state carried by the electron spin by orders of magnitude. The realization of a cloning machine with built-in quantum memory provides a key step for application of quantum cloning in quantum information science.

Tyrosinase and tyrosinase-related protein 1 (Tyr-Tyrp1) complex plays a critical role in the synthesis of melanin intermediates, which involves the production of reactive oxygen species (ROS) and contributes to the development of vitiligo. Based on our previous observation that rs11614913 single nucleotide polymorphism (SNP) in miR-196a-2 could affect the risk of vitiligo by influencing Tyrp1 , we hypothesized that the same SNP could also regulate the level of Tyr in vitiligo. The aim of this study was to evaluate the potential association between rs11614913 SNP in miR-196a-2 and serum Tyr level in vitiligo and the regulatory role of miR-196a-2 in the expression of Tyr in melanocytes. The serum Tyr level was detected in 116 patients with vitiligo and 116 controls by ELISA plate assay. The expression level of Tyrp1 and Tyr in PIG1(normal melanocyte cell lines) cells was analyzed by western blotting. The ROS level and apoptosis rate in PIG1 cells transfected with si- Tyr or control siRNA were tested by flow cytometry. The results show that the individuals with TT+TC genotypes in miR-196a-2 and higher Tyr level in serum had an increased risk of vitiligo compared with those who had the CC genotype and lower Tyr level ( P  < 0.001). Furthermore, the rs11614913 C allele in miR-196a-2 enhanced its inhibitory regulation on the expression of Tyr, the down-regulation of which in melanocytes successfully reduced the intracellular ROS levels and the apoptosis rate. In conclusion, our findings suggest that miR-196a-2 polymorphisms can regulate the Tyr levels, which influences the susceptibility of vitiligo.

For deep excavations in residual soils that are underlain by highly fissured or fractured rocks, it is common to observe the drawdown of the groundwater table behind the excavation, resulting in seepage-induced ground settlement. In this study, finite element analyses are firstly performed to assess the critical parameters that influence the ground settlement performance in residual soil deposits subjected to groundwater drawdown. The critical parameters that influence the ground settlement performance were identified as the excavation width, the excavation depth, the depth of groundwater drawdown, the thickness of the residual soil, the average SPT N60 value of the residual soil, the location of the moderately weathered rock, and the wall system stiffness. Subsequently, an artificial neural network (ANN) model was developed to provide estimates of the maximum ground settlement. Validation of the performance of ANN model was carried out using additional data derived from finite element analyses as well as with measured data from a number of excavation sites.