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Discovering knowledge from data is a quantum jump from quantity to quality, which is the characteristic and the spirit of the development of science. Symbolic regression (SR) is playing a greater role in the discovery of knowledge from data, specifically in this era of exponential data growth, because SRs are able to discover mathematical formulas from data. These formulas may provide scientifically meaningful models, especially when combined with domain knowledge. This article provides an overview of SR applications in the field of materials science and engineering. Integrating domain knowledge with SR is the key and a crucial approach, which allows gaining knowledge from data quickly, accurately, and scientifically. In the data-driven paradigm, SR allows for uncovering the underlying mechanisms of materials behavior, properties, and functions, in a wide range of areas from basic academic research to industrial applications, including experiments and computations, by providing explicit interpretable models from data, in comparison with other machine-learning “black-box” models. SR will be a powerful tool for rational and automatic materials development.
There is a genuine need to shorten the development period for new materials with desired properties. In this work, machine learning (ML) was conducted on a dataset of the elastic moduli of 219 bulk-metallic glasses (BMGs) and another dataset of the critical casting diameters (Dmax) of 442 BMGs. The resulting ML model predicted the moduli and Dmax of BMGs in good agreement with most experimentally measured values, and the model even identified some errors reported in the literature. This work indicates the great potential of ML in design of advanced materials with target properties.
Two wide band gap conjugated polymers, namely PBDT-TT25 and PBDT-TT36, derived from (4,8-bis(4,5-dioctyl-thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane) with 2,5-dibromothieno[3,2-b]thiophene (TT25) or 3,6-dibromothieno[3,2-b]thiophene (TT36), have been synthesized by simply altering the linker positions of thieno[3,2-b]thiophene unit. The impact of linker positions on the energy levels, aggregation, active layer morphology, and optical and photovoltaic properties was evaluated systemically. We found that the absorption was greatly broadened, and the highest occupied molecular orbital (HOMO) energy level was elevated as the result of the significantly reduced twist angle on the polymer backbone when the linker positions changed from 3,6-isomer to 2,5-isomer. Therefore, the optimal inverted polymer solar cells exhibited a 1.87 times enhancement in power conversion efficiencies (PCE), which was mainly ascribed to the higher short circuit current densities (JSC) and fill factor (FF) of the devices mainly benefited from the widened, stronger absorption, higher hole mobility, and more ordered structure.
The association between gestational weight gain (GWG) and exclusive breast-feeding (EBF) practices remains unclear. The present study evaluated the association between GWG and EBF in the first 6 months postpartum among primiparas in rural China.
The study population was drawn from a previous randomized controlled trial, and the relevant data were obtained from an electronic, population-based perinatal system and a monitoring system for child health care. GWG was categorized according to the guidelines of the Institute of Medicine.
Five rural counties in Hebei Province, China.
A total of 8449 primiparas.
Of the women, 58·7 % breast-fed exclusively for the first 6 months postpartum. Overweight women who gained either more or less weight than the recommended GWG tended to experience failure of EBF (OR=0·49; 95 % CI 0·34, 0·70; P<0·001 and OR=0·79; 95 % CI 0·63, 0·99; P=0·048, respectively). The same results were also observed among obese women; the OR for lower and greater weight gain were 0·28 (95 % CI 0·08, 0·94; P=0·04) and 0·55 (95 % CI 0·32, 0·95; P=0·03), respectively.
GWG that is below or above the Institute of Medicine recommendations is associated with EBF behaviour for the first 6 months postpartum in overweight and obese primiparas in rural China.
To investigate a Middle East respiratory syndrome coronavirus (MERS-CoV) outbreak event involving multiple healthcare facilities in Riyadh, Saudi Arabia; to characterize transmission; and to explore infection control implications.
Cases presented in 4 healthcare facilities in Riyadh, Saudi Arabia: a tertiary-care hospital, a specialty pulmonary hospital, an outpatient clinic, and an outpatient dialysis unit.
Contact tracing and testing were performed following reports of cases at 2 hospitals. Laboratory results were confirmed by real-time reverse transcription polymerase chain reaction (rRT-PCR) and/or genome sequencing. We assessed exposures and determined seropositivity among available healthcare personnel (HCP) cases and HCP contacts of cases.
In total, 48 cases were identified, involving patients, HCP, and family members across 2 hospitals, an outpatient clinic, and a dialysis clinic. At each hospital, transmission was linked to a unique index case. Moreover, 4 cases were associated with superspreading events (any interaction where a case patient transmitted to ≥5 subsequent case patients). All 4 of these patients were severely ill, were initially not recognized as MERS-CoV cases, and subsequently died. Genomic sequences clustered separately, suggesting 2 distinct outbreaks. Overall, 4 (24%) of 17 HCP cases and 3 (3%) of 114 HCP contacts of cases were seropositive.
We describe 2 distinct healthcare-associated outbreaks, each initiated by a unique index case and characterized by multiple superspreading events. Delays in recognition and in subsequent implementation of control measures contributed to secondary transmission. Prompt contact tracing, repeated testing, HCP furloughing, and implementation of recommended transmission-based precautions for suspected cases ultimately halted transmission.
In this work, the negatively charged [NbMoO6]− nanosheets (NSs) were combined with positively charged [5,10,15,20-tetrakis (N-methylpyridinium-4-yl) porphyrinato cobalt] (CoTMPyP) to fabricate a sandwich-like CoTMPyP/[NbMoO6]− NSs intercalated material by a direct self-assembling process. The results confirmed that CoTMPyP cations formed an inclined monolayer between [NbMoO6]− NSs and the inclined angle was about 68°. The electrochemical properties of CoTMPyP/[NbMoO6]− NSs composite were also investigated by cyclic voltammetry and liner sweep voltammetry, which showed the enhanced electron transferred ability. The CoTMPyP/[NbMoO6]− NSs modified electrode displayed excellent electrocatalytic activity towards oxygen reduction with the reduction peak potential shifting from −0.681 to −0.235 V. And oxygen could be reduced to generate hydrogen peroxide with a two-electron process in neutral electrolytes. Moreover, the reduction peak current was linear relationship with the square root of scan rates, implying that the catalytic reaction depended on oxygen diffusion.
The composites were synthesized by the reaction of Bi(NO3)3·5H2O, KI, and MoS2 and were prepared with different molar ratios of Bi/Mo (1:5, 1:2, 1:1, and 4:1) by altering the amount of bismuth nitrate pentahydrate. The phase composition and chemical bonds of the composites were characterized via X-ray diffraction and FT-IR, and the morphologies of the samples were characterized via scanning electron microscopy. With the increase of lanthanum source, the lamellar structure of the sample surface became more and more obvious. The results showed that the phase composition of the composites with different ratios of Bi/Mo was different. When the Bi/Mo reached 4:1, the composite material was Bi2MoO6/BiOI. The heterojunction structure formed between Bi2MoO6 and BiOI effectively promotes the separation of photogenerated electrons and holes and improved the photocatalytic activity. Therefore, the effect of the composites on the degradation of RhB was better than pure BiOI under the irradiation of a 350-W xenon lamp.
In this work, a N-doped CsTi2NbO7@g-C3N4 (NTCN) heterojunction nanocomposite was synthesized by a simple one-step calcination method. The as-prepared samples were characterized by means of X-ray diffraction patterns, scanning electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, and Fourier transformed infrared spectroscopy. The results showed that g-C3N4 was formed both on the surface and within the interlayers of CsTi2NbO7, in which CsTi2NbO7 was in situ doped by nitrogen atoms to form N–CsTi2NbO7. The NTCN composite displayed higher electrocatalytic activity toward the detection of nitrite than pure CsTi2NbO7 and g-C3N4. The main reasons could be attributed to the synergistic effects of morphology engineering, N-doping, and layered heterojunction. The NTCN-based electrochemical sensor expressed a good linear relationship range from 0.0999 to 3.15 mmol/L with a detection limit of 2.63 × 10−5 mol/L. The good recovery, stability, and reproducibility of this biosensor showed the potential application in environmental monitoring.
A new acoustic positioning method for Autonomous Underwater Vehicles (AUV) that uses a single underwater hydrophone is proposed in this paper to solve problems of Long Baseline (LBL) array laying and communication synchronisation problems among all hydrophones in the traditional method. The proposed system comprises a Strapdown Inertial Navigation System (SINS), a single hydrophone installed at the bottom of the AUV and a single underwater sound source that emits signals periodically. A matrix of several virtual hydrophones is formed with the movement of the AUV. In every virtual LBL window, the time difference from the transmitted sound source to each virtual hydrophone is obtained by means of a Smooth Coherent Transformation (SCOT) weighting cross-correlation in the frequency domain. Then, the recent location of the AUV can be calculated. Simulation results indicate that the proposed method can effectively compensate for the position error of SINS. Thus, the positioning accuracy can be confined to 2 m, and the method achieves good applicability. Compared with traditional underwater acoustic positioning systems, the proposed method can provide great convenience in engineering implementation and can reduce costs.
OBJECTIVES/SPECIFIC AIMS: To demonstrate that olanzapine recapitulates the effect of increased lateral hypothalamic (LH) GABAergic activity in the DRN and the DBB. This will provide a potential neural substrate for the observed increase in consumption of food and weight gain. METHODS/STUDY POPULATION: (1) We will examine electrophysiological activity of the DRN and the DBB in response to optogenetic stimulation of LH fibers to these nuclei. (2) We will identify the behavioral phenotype of stimulating these same projections using optogenetic techniques. (3a) Identify the behavioral phenotype of mice possessing cre-loxp-dependent knockout (KO) of LH GABAergic activity, DRN serotonergic activity, and inhibition of DBB cholinergic activity. (3b) Using these mice, we will establish behavioral response to olanzapine in ad libitum feeding and fast-refeeding condition. (4) Using baseline and post-treatment body mass index (BMI), PANSS, and side effect profile scores from a recently completed prospective cohort study of treatment-naive schizophrenic patients receiving atypical antipsychotics for 1 year, we will sequence multiple single nucleotide polymorphisms and explore the correlation of serotonergic, dopaminergic, and cholinergic receptor mutations with the increase in BMI and changes in PANSS score and side effect scores. RESULTS/ANTICIPATED RESULTS: (1) Our preliminary data indicates that the LH exclusively sends GABAergic input to the DBB, and the large majority of its projections to the DRN are GABAergic. (2) We have identified that stimulating LH–>DBB projections produces intense feeding and drinking behavior, a real-time place preference for laser stimulation, and a conditioned place preference for laser stimulation. Preliminary data shows that the LH->DRN also produces feeding behavior. (3a) Our lab has demonstrated that transgenic mice with LH-specific GABA release KO are smaller, have increased anxiety-like behaviors such a repetitive grooming and open field aversion, and have reduced feeding after fasting conditions. We expect the DRN serotonergic KO mice to have increased body weight and reduced anxiety-like behaviors. (3b) Our pilot study demonstrated that the LH GABA KO mice administered olanzapine have a greater consumption of food over 1 hour than controls (n=7, 5, respectively; p=0.08). DRN serotonergic KO mice and mice with inhibition of choline will have an increased baseline feeding behavior, but will not be affected by olanzapine. (4) We believe that SNPs in serotonergic receptors such as 5HT2C, and those affecting dopaminergic and cholinergic receptors, will be more common in schizophrenic patients with increased BMI than those without. Further, we believe that a reduction in the PANSS items reflecting anxiety and aversiveness will correlate with increased BMI, since we postulate that mimicking LH GABAergic activity will produce its previously demonstrated anxiolytic effects. DISCUSSION/SIGNIFICANCE OF IMPACT: Identifying the important role for a reward-oriented feeding center in the brain in producing antipsychotic weight gain will allow a more comprehensive, ethologically sound approach to behavioral modification therapy in these patients. It will lend mechanistic credence to weight control therapies which have used token economy, opioid antagonism, and other inhibition-promoting therapies. This study will also increase the validity for testing further the use of selective serotonin agonists which prevent weight gain such as lorcaserin.
Glacier surface melting can be described using energy-balance models. We conducted a surface energy budget experiment to quantify surface energy fluxes and to identify factors affecting glacial melt in the ablation zone of Laohugou glacier No. 12, western Qilian mountains. The surface energy budget was calculated based on data from an automatic weather station, and turbulent fluxes calculated using the bulk-aerodynamic approach were corrected using measurements from an eddy-covariance system. Simulated mass balances were validated by stake observations. Net shortwave radiation was the primary component of the surface energy balance (126Wm–2), followed by sensible heat flux. Net longwave radiation (–45Wm–2) and latent heat flux (–12.8 Wm–2) represented heat sinks. The bulk-aerodynamic method underestimated sensible and latent heat fluxes by 3.4 and 1.2 W m–2, respectively. The simulated total mass balance of –1703mmw.e. exceeded the observed total by 90 mm w.e. Daily positive accumulated temperature and low albedo were the main factors accelerating glacier melt. An uncertainty assessment showed that mass balance was very sensitive to albedo and varied by 36% when albedo changed by 0.1.
The Yellow Sea region is of high global importance for waterbird populations, but recent systematic bird count data enabling identification of the most important sites are relatively sparse for some areas. Surveys of waterbirds at three sites on the coast of southern Jiangsu Province, China, in 2014 and 2015 produced peak counts of international importance for 24 species, including seven globally threatened and six Near Threatened species. The area is of particular global importance for the ‘Critically Endangered’ Spoon-billed Sandpiper Calidris pygmaea (peak count across all three study sites: 62 in spring  and 225 in autumn  and ‘Endangered’ Spotted Greenshank Tringa guttifer (peak count across all three study sites: 210 in spring  and 1,110 in autumn ). The southern Jiangsu coast is therefore currently the most important migratory stopover area in the world, in both spring and autumn, for both species. Several serious and acute threats to waterbirds were recorded at these study sites. Paramount is the threat of large-scale land claim which would completely destroy intertidal mudflats of critical importance to waterbirds. Degradation of intertidal mudflat habitats through the spread of invasive Spartina, and mortality of waterbirds by entrapment in nets or deliberate poisoning are also real and present serious threats here. Collisions with, and displacement by, wind turbines and other structures, and industrial chemical pollution may represent additional potential threats. We recommend the rapid establishment of effective protected areas for waterbirds in the study area, maintaining large areas of open intertidal mudflat, and the urgent removal of all serious threats currently faced by waterbirds here.
The Endangered snow leopard Panthera uncia is a flagship species of mountainous central Asia, and a conservation concern. China has the largest extent of potential snow leopard habitat and is thus crucial for snow leopard conservation. There are many challenges to snow leopard conservation in China, however, and there is still little information on the species for many geographical locations, including the Tianshan Mountains of Xinjiang province, which are important because they potentially connect snow leopard populations in Krygyzstan and Kazakhstan with those in Mongolia. We used camera traps in four areas across eastern, central and western Tianshan, with a total survey effort of 3,216 camera-trapping days. We confirmed the presence of snow leopards and an abundance of potential snow leopard prey, including the Siberian ibex Capra sibirica, in all areas. We found 2–3 individual adult snow leopards at each site, with relatively limited survey effort, and more study is needed to fully investigate the importance of the Tianshan Mountains for the species. Establishing more protected areas is essential for snow leopard conservation, and we have used data from this study to apply for protected area status for several areas.
Knowledge of present-day ice temperature and velocity is important in order to determine how fast a glacier will respond to present and future climate change. We apply a two-dimensional higher-order thermomechanical flowband model to simulate present-day ice temperature and velocity along the main flowline of East Rongbuk Glacier, Qomolangma (Mount Everest), Himalaya. We use recent (2005–11) observational data to validate the numerical model. Modelled and observed ice surface velocities exhibit good agreement. Modelled ice temperatures agree well with observed values in two shallow boreholes that are ∼18 m deep. The model suggests that the ablation zone of East Rongbuk Glacier, km 4 to km 10 from the glacier head, is underlain by temperate ice.
For many regions, glacier inaccessibility results in sparse geometric datasets for use as model initial conditions (e.g. along the central flowline only). In these cases, two-dimensional (2-D) flowline models are often used to study glacier dynamics. Here we systematically investigate the applicability of a 2-D, first-order Stokes approximation flowline model (FLM), modified by shape factors, for the simulation of land-terminating glaciers by comparing it with a 3-D, ‘full’-Stokes ice-flow model (FSM). Based on steady-state and transient, thermomechanically uncoupled and coupled computational experiments, we explore the sensitivities of the FLM and FSM to ice geometry, temperature and forward model integration time. We find that, compared to the FSM, the FLM generally produces slower horizontal velocities, due to simplifications inherent to the FLM and to the underestimation of the shape factor. For polythermal glaciers, those with temperate ice zones, or when basal sliding is important, we find significant differences between simulation results when using the FLM versus the FSM. Over time, initially small differences between the FLM and FSM become much larger, particularly near cold/temperate ice transition surfaces. Long time integrations further increase small initial differences between the two models. We conclude that the FLM should be applied with caution when modelling glacier changes under a warming climate or over long periods of time.
We investigate the defect structures around a spherical colloidal particle in a cholesteric liquid crystal using spectral method, which is specially devised to cope with the inhomogeneity of the cholesteric at infinity. We pay particular attention to the cholesteric counterparts of nematic metastable configurations. When the spherical colloidal particle imposes strong homeotropic anchoring on its surface, besides the well-known twisted Saturn ring, we find another metastable defect configuration, which corresponds to the dipole in a nematic, without outside confinement. This configuration is energetically preferable to the twisted Saturn ring when the particle size is large compared to the nematic coherence length and small compared to the cholesteric pitch. When the colloidal particle imposes strong planar anchoring, we find the cholesteric twist can result in a split of the defect core on the particle surface similar to that found in a nematic liquid crystal by lowering temperature or increasing particle size.
We analyze in this paper the pressure splitting scheme of a partitioned semi-implicit coupling algorithm for fluid-structure interaction (FSI) simulation. The semi-implicit coupling algorithm is developed on the ground of the artificial compressibility characteristic-based split (AC-CBS) scheme that serves not only for the fluid subsystem but also for the global FSI system. As the dual-time stepping procedure recommended for quasi-incompressible flows is incorporated into the implicit coupling stage, the fluctuating pressure may be unusually susceptible to the AC coefficient. Moreover, it is not trivial to devise an optimal AC formulation for pressure estimation. Instead, we consider a stabilized second-order pressure splitting scheme in the AC-CBS-based partitioned semi-implicit coupling algorithm. Computer simulation of a benchmark FSI experiment demonstrates that good agreement is exposed between the available and present data.
crAssphage is a newly discovered gut bacteriophage. However, its pathogenicity and molecular epidemiology in humans are as yet unclear. In this study, we investigated the association between crAssphage and diarrhoea, as well as the molecular epidemiology of crAssphage in Chinese patients from our hospital. Our results indicated that there were no significant differences in the crAssphage-positive ratio and viral loads in faecal supernatants between adults with diarrhoea and healthy adults. Of infants and children with diarrhoea, 2·8% were found to be crAssphage-positive, including two infants aged <1 month. Markedly, of all confirmed crAssphage-positive strains, 100% had the ORF00039 deletion and 77·8% had low identity of ORF00018 compared to crAssphage (GenBank accession no. NC_024711, designated genotype 1). Thus, crAssphage was not associated with diarrhoea and most strains of crAssphage in Chinese patients (designated genotype 2) were characterized by the ORF00039 deletion and low identity of ORF00018.
In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed. On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a laser-driven strong magnetic field up to 200 T has been achieved. The experiment was performed to model the interaction of solar wind with dayside magnetosphere. Also the low beta plasma magnetic reconnection (MR) has been studied. Theoretically, the model has been developed to deal with the atomic structures and processes in strong magnetic field. Also the study of shock wave generation in the magnetized counter-streaming plasmas is introduced.
Coronary fistula is defined as an anomalous connection between a coronary artery and any of the four chambers of the heart or any of its great vessels. A coronary fistula connecting the left main coronary artery to the right atrium is the most uncommon. In the present study, we report the surgical management of a very uncommon case of an aneurysm-like fistula connecting the left main coronary artery to the right atrium in a 2-year-old boy.