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Quantum simulation of 1D relativistic quantum mechanics has been achieved in well-controlled systems like trapped ions, but properties like spin dynamics and response to external magnetic fields that appear only in higher dimensions remain unexplored. Here we simulate the dynamics of a 2D Weyl particle. We show the linear dispersion relation of the free particle and the discrete Landau levels in a magnetic field, and we explicitly measure the spatial and spin dynamics from which the conservation of helicity and properties of antiparticles can be verified. Our work extends the application of an ion trap quantum simulator in particle physics with the additional spatial and spin degrees of freedom.

The Jaynes-Cummings-Hubbard (JCH) model is a fundamental many-body model for light-matter interaction. As a leading platform for quantum simulation, the trapped ion system has realized the JCH model for two to three ions. Here, we report the quantum simulation of the JCH model using up to 32 ions. We verify the simulation results even for large ion numbers by engineering low excitations and thus low effective dimensions; then we extend to 32 excitations for an effective dimension of 2^{77}, which is difficult for classical computers. By regarding the phonon modes as baths, we explore Markovian or non-Markovian spin dynamics in different parameter regimes of the JCH model, similar to quantum emitters in a structured photonic environment. We further examine the dependence of the non-Markovian dynamics on the effective Hilbert space dimension. Our Letter demonstrates the trapped ion system as a powerful quantum simulator for many-body physics and open quantum systems.

Quantum simulation provides important tools in studying strongly correlated many-body systems with controllable parameters. As a hybrid of two fundamental models in quantum optics and in condensed matter physics, the Rabi-Hubbard model demonstrates rich physics through the competition between local spin-boson interactions and long-range boson hopping. Here we report an experimental realization of the Rabi-Hubbard model using up to $16$ trapped ions and present a controlled study of its equilibrium properties and quantum dynamics. We observe the ground-state quantum phase transition by slowly quenching the coupling strength, and measure the quantum dynamical evolution in various parameter regimes. With the magnetization and the spin-spin correlation as probes, we verify the prediction of the model Hamiltonian by comparing theoretical results in small system sizes with experimental observations. For larger-size systems of $16$ ions and $16$ phonon modes, the effective Hilbert space dimension exceeds $2^{57}$, whose dynamics is intractable for classical supercomputers., 6 pages, 3 figures + 13 pages, 10 figures

Differential cross sections for Compton scattering from the proton have been measured at scattering angles of $55^\circ$, $90^\circ$, and $125^\circ$ in the laboratory frame using quasimonoenergetic linearly (circularly) polarized photon beams with a weighted mean energy value of 83.4\,MeV (81.3\,MeV). These measurements were performed at the High Intensity Gamma-Ray Source facility at the Triangle Universities Nuclear Laboratory. The results are compared to previous measurements and are interpreted in the chiral effective field theory framework to extract the electromagnetic dipole polarizabilities of the proton, which gives $\alpha_{E1}^p = 13.8\pm1.2_{\rm stat}\pm0.1_{\rm BSR}\pm0.3_{\rm theo}, \beta_{M1}^p = 0.2\mp1.2_{\rm stat}\pm0.1_{\rm BSR}\mp0.3_{\rm theo}$ in units of 10$^{-4}$\, fm$^3$., Comment: 6 pages, 4 figures. Version identical to the published letter

Trapped ions constitute one of the most promising systems for implementing quantum computing and networking. For large-scale ion-trap-based quantum computers and networks, it is critical to have two types of qubits, one for computation and storage, while the other for auxiliary operations like runtime qubit detection, sympathetic cooling, and repetitive entanglement generation through photon links. Dual-type qubits have previously been realized in hybrid systems using two ion species, which, however, introduces significant experimental challenges for laser setup, gate operations as well as the control of the fraction and positioning of each qubit type within an ion crystal. Here we solve these problems by implementing two coherently-convertible qubit types using the same ion species. We encode the qubits into two pairs of clock states of the 171Yb+ ions, and achieve fast and high-fidelity conversion between the two types using narrow-band lasers. We further demonstrate that operations on one qubit type, including sympathetic laser cooling, gates and qubit detection, have crosstalk errors less than 0.03% on the other type, well below the error threshold for fault-tolerant quantum computing. Our work showcases the feasibility and advantages of using coherently convertible dual-type qubits with the same ion species for future large-scale quantum computing and networking., 9 pages, 7 figures

According to the requirements of the Tianlai project, an antenna structure in which the center axis of the rotating reflector coincides with the focus axis of feed is developed. To study the implementation of the structure, there exist some technical difficulties in the light-weight design of antenna back frame, virtual axis structure design and so on. Firstly, the structure of the traditional antenna reflector back frame is analyzed, and the possibility of applying the technology of tension structure, cable-truss structure and arch structure to the antenna backrest structure is studied theoretically to achieve lightweight. An antenna backrest unit structure is designed and optimized, and the mass is reduced by 40.5%. Antenna element model is established for the simulation analysis. The effects of load and elevation angle on the structural performance of the antenna back frame unit are studied, and the antenna mechanical characteristics are checked. Simulation results show that the precision of the antenna reflector can meet the requirements. The theory of the lightweight structure of antenna reflector back frame in this paper is feasible, and it also has certain reference value for other large steerable cylindrical antenna design, but it still needs prototype development and experimental research.

In the second phase of the Tianlai project, a large parabolic cylindrical antenna array with a size of 100 m × 100 m will be built. Three kinds of pitching schemes for the cylindrical antenna were developed. In order to measure the elevation angle in different pitching schemes universally, the GNSS-based (Global Navigation Satellite System based) elevation-angle-measurement method is proposed in this paper. First of all, the geometrical and physical principles of the new measurement method are analyzed. Then, five kinds of measurement system layouts are designed and compared from high accuracy, low-power consumption, low cost, anti-interference, and high reliability. Next, an experimental scheme of the GNSS-based elevation-angle-measurement method is developed, and the experiment is carried out. Finally, the error of the elevation angle measured by experiment is analyzed. The experimental result shows that the new method can meet the precision requirements of elevation angle measurement for the cylindrical antenna in the second phase of the Tianlai project. This paper also provides a reference for the elevation angle measurement of other large cylindrical antennas.

Fibre reinforcement technology, which has been widely used in geotechnical engineering, such as, ground treatment, slope protection, retaining wall and so on, can effectively improve the bearing capacity and the shear strength of soil body. The present study is aimed at determining the behaviour of silty clay reinforced with sisal fibre in a random manner. The soil used is a type of silty clay which is representative in Qingdao District. The fibres are cut to different lengths (5, 10 and 15 mm) and mixed randomly with soil in varying percentages (0·5, 1·0 and 1·5%). The test results indicate an improvement in the strength, deformation and shear failure characteristics of soil due to the addition of sisal fibres. Additionally, the cohesion and the peak of the principal stress difference of the sisal fibre reinforced soil are improved to some extent compared with the plain soil.

The Beijing Heart Lung and Blood Vessel Medical Center has participated in the World Health Organisation MONICA project since 1981. Our study, named Sino-MONICA-Beijing, has been carried out in Beijing and covers a population approximately of 700,000. After a 2-year pilot study, the project started formally January 1, 1984. This paper presents the organization and methodology of the study, with emphasis on the monitoring system and on how events were found. The main results of the cardiovascular disease (CVD) event monitoring are as follows: average annual mortality from all causes, for the 3-year period of 1984-86 was 319/100,000 for men and 238/100,000 for women aged 25-64; from CVD 119/100,000 for men and 101/100,000 for women; from ischemic heart disease 29/100,000 for men and 14/100,000 for women; and from cerebrovascular disease 59/100,000 for men and 52/100,000 for women. Preliminary experience has shown that Sino-MONICA-Beijing is a well-standardized project of long-term surveillance of CVD in the communities of Beijing.

Serotonin [5-hydroxytryptamine (5HT)] is a vasoconstrictor that also acts as a developmental signal early in embryogenesis. The 5HT transporter (SERT) on the membranes of the placental trophoblast cells controls 5HT levels in the maternal bloodstream to maintain stable transplacental blood flow and simultaneously provide 5HT to the embryo. The 5HT uptake rate of placental SERT is important for both the mother and the developing embryo. The impact of glucose on the placental SERT system during diabetic pregnancy is not known. The present in vitro study investigated this important issue in human placental choriocarcinoma (JAR) cells that were cultured for 24-96 h in a medium containing either 5.5 (physiologic concentration) or 25 mmol/L D-glucose (diabetic-like concentration). The 5HT uptake rates of the cultured cells were not altered at exogenous D-glucose concentrations in the range of 5.5-15 mmol/L, but were decreased significantly at a diabetic-like concentration (>or=25 mmol/L). To understand better the role of glucose on the placental 5HT system, we first characterized SERT in JAR cells at different cell-cycle phases and then determined the expression levels of SERT on the plasma membrane and in the intracellular pools of JAR cells at the late-S and G2 phases, where the uptake rates were decreased 73% under diabetic-like glucose concentrations. Finally, the importance of self-association of SERT molecules was examined. In JAR cells co-expressing Flag- and myc-tagged SERT, myc-antibody precipitated 70% of Flag-SERT, indicating that a large percentage of SERT proteins exist as oligomers in situ. Under diabetic conditions, myc-antibody no longer precipitated Flag-SERT, suggesting a disruption in the aggregation of SERT molecules. Therefore, we propose that under uncontrolled diabetic conditions, glucose down-regulates 5HT uptake rates of placental SERT by interfering with its functional expression in a cell-cycle-dependent manner.

Here we report the case of a 69-year-old Chinese Han woman who presented with liver cirrhosis, diabetes mellitus, skin hyperpigmentation, hyperferritinaemia and high transferrin saturation. Subsequent genetic analyses identified a novel heterozygous mutation (p.Cys326Phe) in the SLC40A1 gene. This is the first report regarding a SLC40A1 mutation in the Chinese Han population and provides novel clinical evidence for the importance of p.Cys326 in SLC40A1 gene function.

Objective.At hospital discharge, preterm infants may have low body stores of nutrients, deficient bone mineralization, and an accumulated energy deficit. This double-blind, randomized study evaluated the growth of premature infants with birth weights Methods.Infants were randomized to PDF or TF a few days before hospital discharge with stratification by gender and birth weight (Results.One hundred twenty-five infants were randomized; 74 completed to 6 months' CA and 53 to 12 months' CA. PDF-fed infants weighed more than TF-fed infants at 1 and 2 months' CA, gained more weight from study day 1 to 1 and 2 months' CA, and were longer at 3 months' CA. There were significant interactions between feeding and birth weight group—among infants with birth weights Conclusions.Growth was improved in preterm infants fed a nutrient-enriched postdischarge formula after hospital discharge to 12 months' CA. Beneficial effects were most evident among infants with birth weights

Nanometre-sized kinks and cracks formed in 6H SiC under ball milling (BM) at room temperature have been observed and characterized on the atomic scale using high-resolution electron microscopy (HREM). Observations of the kinks show that numerous positive and negative partials are aligned at either of the kink boundaries, and the stacking sequences in the kink band are considerably different from those in the other areas. It was also observed that the (0001) lattice planes in the kink band are kinked, indicating that microplasticity occurs in the normally brittle material SiC under BM even at room temperature. HREM observations of cracks show that cracks previously observed by transmision electron microscopy are not completely open but are at the initiation stage of fracture. Inside a crack, one residual kink region can be clearly observed, which indicates a correlation between kink and crack, that is a crack evolves from a kink.

The alpha --> beta polytypic transformation in SIC was observed during ball milling at room temperature. Microstructural evolution was characterized on an atomic scale by high-resolution electron microscopy (HREM). HREM observations showed that partial dislocations play an important role in the transformation under the complicated conditions during ball milling.

Five underground explosion tests were carried out to investigate the coupling effect of explosive charges on ground vibrations. Among them, one was fully coupled detonation, one was water coupled detonation and three of them were decoupled detonations with the charged explosive density ρec of 5, 10 and 20 kg/m3, respectively. Accelerations in rock mass free field and on rock surface at different distance from the explosion centre and the airblast pressures in a charge chamber were recorded. In this paper, the test results arc presented. The effects of coupling and the charge density on ground vibrations are discussed and compared with those obtained by other researchers.

Although well established as a reliable method for forming new cyclopentenone rings from acyclic precursors, the Nazarov reaction has been the subject of substantial recent work. The effect of substituents on 1,4-dien-3-one precursors is discussed. Asymmetric methods are presented, including chirality transfer, chiral Lewis acids, and asymmetric organocatalysis. An overview is given of various ‘interrupted’ variants, in which cyclized intermediates undergo domino trapping reactions with either nucleophilic or electrophilic reagents. Finally, cyclization via alternative and unconventional precursors is described, including the vinylogous and iso-Nazarov reactions, transition metal activation of alkyne-containing substrates, and the aza-Nazarov reaction.

The first measurement of the three-body photodisintegration of longitudinally polarized (3)He with a circularly polarized γ-ray beam was carried out at the High Intensity γ-ray Source facility located at Triangle Universities Nuclear Laboratory. The spin-dependent double-differential cross sections and the contributions from the three-body photodisintegration to the (3)He Gerasimov-Drell-Hearn integrand are presented and compared with state-of-the-art three-body calculations at the incident photon energies of 12.8 and 14.7 MeV. The data reveal the importance of including the Coulomb interaction between protons in three-body calculations.

Some basic quantitative analysis techniques of digitized high resolution atomic image are developed in this paper. We describe how to divide the atomic image into small independent areas with special structure information by the valley mesh segmentation method. The procedure is with regard to the bright contrast spot segmentation of atomic images. We suggest several ways for bright contrast spot localization in images. Calculation routines for peak detection and weighted local position average methods for this purpose are given. (C) 1996 Wiley-Liss, Inc.

The second J(π)=2+ state of 12C, predicted over 50 years ago as an excitation of the Hoyle state, has been unambiguously identified using the 12C(γ,α0)(8)Be reaction. The alpha particles produced by the photodisintegration of 12C were detected using an optical time projection chamber. Data were collected at beam energies between 9.1 and 10.7 MeV using the intense nearly monoenergetic gamma-ray beams at the HIγS facility. The measured angular distributions determine the cross section and the E1-E2 relative phases as a function of energy leading to an unambiguous identification of the second 2+ state in 12C at 10.03(11) MeV, with a total width of 800(130) keV and a ground state gamma-decay width of 60(10) meV; B(E2:2(2)+→0(1)+)=0.73(13)e(2) fm(4) [or 0.45(8) W.u.]. The Hoyle state and its rotational 2+ state that are more extended than the ground state of 12C presents a challenge and constraints for models attempting to reveal the nature of three alpha-particle states in 12C. Specifically, it challenges the ab initio lattice effective field theory calculations that predict similar rms radii for the ground state and the Hoyle state.

This study aimed to analyze the epidemiologic patterns of pediatric critically-ill patients presenting to the emergency department (ED) and the etiologies of intensive care unit (ICU) admission of different age groups.This retrospective study of all children aged less than 18 years presenting with critical illnesses to the ED was conducted in a tertiary medical center in Taiwan from 2003 to 2007. All patients transferred to the ICU from the ED were included without distinction. Demographic data of critically-ill children admitted to the ED and ICU were analyzed. Etiologies of the ICU admissions were analyzed by various age groups.There were 2978 critically-ill children admitted to the ICU from the ED. In 120 pediatric patients with out-of-hospital cardiac arrest, cases with pulseless electrical activity or ventricular fibrillation had higher successful CPR rates than patients with asystole (both p0.05). In patients admitted to ICUs, complications from the perinatal period, respiratory system diseases, accidental injuries and poisoning were the predominant etiologies respectively in young children (42.5%), school-aged children (38.5%), and adolescents (47.9%). Moreover, the most common of which was respiratory distress syndrome in neonates followed by bacterial pneumonia and status epilepticus.Epidemiologic analysis may provide primary clinicians to identify significant differences in admission rates based on different etiologies of various age groups.

Comparing to conventional fossil fuels, hydrogen yields no emission through various thermal and electro-chemical processes. Beyond this feature, high energy density and transportability make hydrogen an attractive candidate for the future energy systems. Hydrogen gas can be harvested from a wide selection of hydrogen enriched molecules through different reforming processes. Among a variety of fuel candidates, water is a readily available resource; and electrolysis of water can take place in relatively low temperature and low pressure. In this paper, solar energy is harvested by the photovoltaic panels, and processed using a dc-dc converter to supply an alkaline electrolyzer. Due to the complexity of the electrolyzer load, the small signal model is obtained firstly using the current/load perturbation method at the rated operation condition. In order to supply low ripple current to the electrolyzer stack, a dual-phase synchronous buck converter is designed and implemented in a dedicated hardware prototype. The control algorithm is implemented in a digital signal controller and the steady state performance of the system is experimentally verified.

OBJECTIVE To determine whether fetal ultrasound early in the third trimester can identify Latina with mild gestational diabetes mellitus (GDM) whose fetuses are at risk for macrosomia and, if so, whether maternal insulin therapy can reduce that risk. RESEARCH DESIGN AND METHODS Study subjects included 303 consecutive women with GDM and a fasting serum glucose level RESULTS Diet and diet-plus-insulin groups were well matched for maternal age, prepregnancy relative weight, weight gain during pregnancy, and glycemia at entry. Insulin therapy reduced maternal capillary (P < 0.005) and MTT (P < 0.001) glucose levels and prevented a diet-associated rise in MTT triglyceride levels (P < 0.002). Gestational age at delivery was similar in insulin- and diet-treated groups (39.6 ± 0.2 vs. 39.5 ± 0.2 weeks). Birth weights (3,647 ± 67 vs. 3,878 ± 84 g; P < 0.02), the prevalence of large-for-gestational age infants (13 vs. 45%, P < 0.02), and neonatal skin-fold measurements at three sites (P < 0.005) were reduced in the insulin-treated group. Rates of transient neonatal hypoglycemia were low in both treatment groups (14 and 18%, respectively) and didnot differ significantly between groups. CONCLUSIONS Fetal ultrasound early in the third trimester identified women with mild GDM whose infants were at high risk for fetal macrosomia in the absence of standard glycemic criteria for insulin therapy. Insulin treatment reduced the macrosomia, indicating that fetal ultrasound can be used to guide metabolic therapy in pregnancies complicated by mild GDM.

The widespread concept of total customer value helps raise the issue of how to generate value through user-centric view. This article puts its emphasis on the sources of customer value creation and corresponding innovations strategies, which were validated through a pilot study in Taiwan. This study also compares commonalities and unique characteristics on three fashion products from the customer value creation perspective through the survey. The following implications are concluded. First, nine factors and 51 elements were identified to be useful for increasing customer value for Asian or Chinese people. Moreover, some factors (e.g., emotional and delicacy factors) are found different from those discussed in previous studies. Finally, practical guidelines for value-based innovation are also discussed in this paper.

This study was conducted to evaluate the effect of medium-chain triglycerides (MCT) in a formula for low-birth-weight (LBW) infants on gastrointestinal tolerance, fat absorption, plasma ketone levels, and urinary dicarboxylic acid (DCA) excretion. At the start of enteral feedings, 64 LBW infants (< or = 1500 g) were randomly assigned to one of four experimental formulas. The formulas contained either 0, 17, 34, or 50% of the total fat as MCT oil. The nonfat constituents of all four formulas were the same and identical to Similac Special Care 24 (SCF). Infants were studied from the start of enteral feeding until approximately 7 days after reaching full feeds. Growth and tolerance were assessed in all infants over the entire feeding period. A 48-h balance study was conducted after enteral intake exceeded 100 kcal/kg/day for 3 days. Stool fat, plasma D-(-)-3-hydroxybutyrate (3HB) and carnitine, serum glucose, and urinary DCA levels were determined. Groups did not differ in growth, formula intake, fat absorption (76-84%), serum glucose, or plasma carnitine levels. Gastrointestinal tolerance was excellent and did not differ among groups. Plasma 3HB was significantly different (p < 0.05) only between the 0 and 50% MCT groups, 50 +/- 10 versus 120 +/- 20 microM, respectively. The excretion of urinary DCAs increased with increasing amounts of MCT in the formula. In conclusion, fat absorption and gastrointestinal tolerance were not affected by different MCT levels (0 to 50% of the total fat), but higher levels of plasma 3HB and urinary DCAs were associated with higher levels of MCT in the LBW formulas studied.

A 41-year-old woman who suffered from monthly haemoptysis for >16 years was referred to a chest surgeon due to an abnormal chest radiograph. The haemoptysis usually occurred on the first day of her menses and lasted ∼3 days. She had poliomyelitis during her childhood and underwent two caesarean sections about two decades previously. There was no prior history of dysmenorrhoeal or abnormal vaginal bleeding. Physical examinations and laboratory investigations were unremarkable. The chest radiograph (fig 1A) showed a right lower lobe nodule. CT scan …