To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We propose a novel Fabry–Pérot (FP) antenna consisting of a checkered polarization-conversion metasurface (PCM), corner-cut square patch antennas, and sandwiched compounds. The proposed antenna achieves low radar-cross-section (RCS), high gain, and wideband circular polarization (CP). The corner-cut square patch antennas facilitate high reflectivity, satisfactory transmission magnitude, and the desired phase difference. An embedded metal between two rings of substrate contributes to reducing cross-polarization, improving transmission efficiency, enhancing bandwidth, and reducing RCS. Following simulations, we fabricated a prototype of the proposed antenna and tested its performance. Measurements from the simulation and prototype tests were similar within a reasonable margin of error. Compared with alternative antennas, our proposed FP antenna offers high gain, wideband CP, low cost, a low RCS, and a lower profile.
Salt marshes have been useful study systems for community ecologists. They are amenable to experimental manipulation, and the simplicity and strong abiotic gradients of salt marshes lead to clear patterns and experimental outcomes. Many early ecologists believed that salt marsh ecosystems were primarily controlled by bottom-up factors (i.e., that nutrients, salinity, and other abiotic factors were the primary factors regulating productivity, and that productivity in turn regulated ecosystem trophic structure). More recently, many ecologists have argued that consumers have an important role in structuring salt marsh ecosystems through “top-down” processes. A simple conceptual approach, which we take here, is to think of salt marsh communities as being structured by bottom-up, top-down, and non-trophic processes.
This research involves a compact wideband circularly-polarized antenna array, which consists of a sequential rotating phase feed network, 2 × 2 mushroom-type metamaterial (MTM) unit, and so on. Each antenna array unit contains a microstrip feedline, an L-shaped slot antenna, and so on. The MTM-based antennas were incorporated with a sequential-phase network of sequentially rotated series-parallel feed to achieve wideband operation. The operational bandwidth and the radiation model in the high-frequency area were improved through the adjustment of spacing between the L-shaped slots while maintaining the size and structure of the MTM. The proposed design had dimensions of 80 mm × 80 mm × 3.5 mm (~1.64 λ0 × 1.64 λ0 × 0.072 λ0 at 6.15 GHz), and it was simulated, fabricated, and tested.
During pulsar navigation, the high-frequency noise carried by the pulsar profile signal reduces the accuracy of the pulse TOA (Time of Arrival) estimation. At present, the main method to remove signal noise by using wavelet transform is to redesign the function of the threshold and level of wavelet transform. However, the signal-to-noise ratio and other indicators of the filtered signal need to be further optimised, so a more appropriate wavelet basis needs to be designed. This paper proposes a wavelet basis design method based on frequency domain analysis to improve the denoising effect of pulsar signals. This method first analyses the pulsar contour signal in the frequency domain and then designs a Crab pulsar wavelet basis (CPn, where n represents the wavelet basis length) based on its frequency domain characteristics. In order to improve the real-time performance of the algorithm, a wavelet lifting scheme is implemented. Through simulation, this method analyses the pulsar contour signal data at home and abroad. Results show the signal-to-noise ratio can be increased by 4 dB, the mean square error is reduced by 61% and the peak error is reduced by 45%. Therefore, this method has better filtering effect.
The poultry red mite, Dermanyssus gallinae, is currently the most common ectoparasite affecting egg-laying hens. Since continuous culture of D. gallinae on birds is a biologically and economically costly endeavour, storage techniques for mites are urgently needed. Effects of temperature on adult and nymph survival were first studied to optimize storage conditions. Then, fecundity of D. gallinae was studied after mites were stored at optimal storage conditions. Results showed the survival rates of protonymphs (42.11%), deutonymphs (8.19%) and females (19.78%) at 5°C after 84 days were higher than those at 0, 25 and 30°C. Thereafter the fecundity and the capability of re-establishing colonies of D. gallinae were evaluated after they were stored for 40 and 80 days at 5°C. After storage, the mean number of eggs showed no statistical difference between treated (5°C for 40 or 80 days) and control groups (25°C for 7 days), while the hatching rates of eggs were in all cases above 97%. The dynamic changes of mite populations and egg numbers showed similar trends to the control group after the stored adult or nymph mites were fed on chicks. Dermanyssus gallinae can be successfully stored at 5°C for 80 days with no interference with the fecundity of mites, and the stored mites could re-establish colonies successfully. Adults and nymphs were two main stages with capability for low temperature storage. These results suggest that low temperature storage is a viable option for colony maintenance of D. gallinae under laboratory conditions.
Pulmonary artery sling is a congenital cardiovascular disease and is usually accompanied by tracheobronchial stenosis. Generally, infants diagnosed with pulmonary artery sling should have surgery. However, the treatment of tracheobronchial stenosis is still controversial. Our team developed a customised, degradable, three-dimensional printed splint and successfully applied it in the treatment of pulmonary artery sling associated with severe bilateral bronchus stenosis. We suggested that three-dimensional printing may be a novel and effective way to treat tracheobronchial stenosis and other diseases in children.
An effective multiplex real-time polymerase chain reaction (PCR) assay for the simultaneous detection of three major pathogens, Nosema bombycis Nägeli (Microsporidia: Nosematidae), Bombyx mori nucleopolyhedrovirus (Baculoviridae: genus Alphabaculovirus) (NPV), and Bombyx mori densovirus (Parvoviridae: genus Iteravirus) (DNV), in silkworms (Bombyx mori (Linnaeus); Lepidoptera: Bombycidae) was developed in this study. Polymerase chain reaction and real-time PCR tests and basic local alignment search tool searches revealed that the primers and probes used in this study had high specificities for their target species. The ability of each primer/probe set to detect pure pathogen DNA was determined using a plasmid dilution panel, in which under optimal conditions the multiplex real-time PCR assay showed high efficiency in the detection of three mixed target plasmids with a detection limit of 8.5×103 copies for N. bombycis and Bombyx mori NPV (BmNPV) and 8.5×104 copies for Bombyx mori DNV (BmDNV). When the ability to detect these three pathogens was examined in artificially inoculated silkworms, our method presented a number of advantages over traditional microscopy, including specificity, sensitivity, and high-throughput capabilities. Under the optimal volume ratio for the three primer/probe sets (3:2:2=N. bombycis:BmNPV:BmDNV), the multiplex real-time PCR assay showed early detection of BmNPV and BmDNV by day 1 post inoculation using DNA templates of the three pathogens in various combinations from individually infected silkworms; the early detection of N. bombycis was possible by day 3 post inoculation using the DNA isolated from the midgut of N. bombycis-infected silkworms.
Psychiatric disorders such as schizophrenia and major depressive disorder
(MDD) are likely to be caused by multiple susceptibility genes, each with
small effects in increasing the risk of illness. Identifying DNA variants
associated with schizophrenia and MDD is a crucial step in understanding
the pathophysiology of these disorders.
To investigate whether the SP4 gene plays a significant
role in schizophrenia or MDD in the Han Chinese population.
We focused on nine single nucleotide polymorphisms (SNPs) harbouring the
SP4 gene and carried out case–control studies in 1235
patients with schizophrenia, 1045 patients with MDD and 1235 healthy
controls recruited from the Han Chinese population.
We found that rs40245 was significantly associated with schizophrenia in
both allele and genotype distributions (Pallele = 0.0005, Pallele = 0.004 after Bonferroni correction; Pgenotype = 0.0023, Pgenotype = 0.0184 after Bonferroni correction). The rs6461563
SNP was significantly associated with schizophrenia in the allele
distributions (Pallele = 0.0033, Pallele = 0.0264 after Bonferroni correction).
Our results suggest that common risk factors in the SP4
gene are associated with schizophrenia, although not with MDD, in the Han
This study examines the usage of the Meaning in Life Questionnaire in Chinese students aged from 10 to 25 within four age groups (N = 5,510): early adolescence (10–13 years old, n = 1,258), middle adolescence (14–17 years old, n = 1,987), late adolescence (18–21 years old, n = 1,950) and early adulthood (22–25 years old, n = 315); and analyses the structure and levels of meaning in life, as well as the relationship between meaning in life and mental health. Results showed that: (1) the Meaning in Life Questionnaire in the four age groups of Chinese students had good construct validity and internal consistency reliability; (2) the average levels of the presence of meaning and search for meaning of Chinese students were moderate or above, and had obvious differences according to gender and family location (i.e., urban vs. rural); (3) the level of presence of meaning showed a trend of rising rapidly in middle adolescence and the level of search for meaning continued to rise in early adolescence and fell rapidly towards the end of adolescence; (4) presence of meaning was positively related to life satisfaction and positive affect and negatively related to depression and negative affect, and the same correlations were found with search for meaning.
This paper describes a new genus Liaous, with L. shaiwensis He and Chen n. gen. n. sp. as the type species, from the Xinyuan Formation of Anisian age in Ziyun, southern Guizhou, China. The phylogenetic tree revealed by the parsimony analysis shows that Liaous is closely allied to both Mentzelia Quenstedt, 1871 and Paramentzelia Xu, 1978 of the subfamily Mentzeliinae. A new classification scheme for the Spiriferinoidea is also proposed based on a phylogenetic tree of the superfamily indicated by parsimony analysis. The Spiriferinoidea includes three families and nine subfamilies. Three new subfamilies—Madoinae He and Chen, new subfam., Qinghaispiriferininae He and Chen, new subfam., and Triadispirinae He and Chen, new subfam. are proposed. Liaous shaiwensis He and Chen n. gen. n. sp. is found in the Posidonia wengensis-Liaous shaiwensis (P-L) paleocommunity, which is dominated by r-strategists (i.e., organisms defined by a fauna with a high dominance and small body sizes) and has a low diversity and high dominance. The P-L paleocommunity therefore has little similarity to its coeval communities from the Anisian Stage of South China and instead it appears more similar to the Lower Triassic shelly faunas in community structures. This paleocommunity is interpreted to have inhabited a relatively deep, low-energy, dysaerobic offshore basin/slope setting with the influence of episodic storms.
In this paper, a novel method is proposed to determine surface residual stress components and their directions based on the spherical indentation. To obtain the direction and the components of a uniaxial or biaxial residual stress, the relationship between the pile-up deformation around an indentation after unloading and the residual stress was firstly systematically studied and established by using numerical simulation. Through theoretical analysis and numerical simulation, we found that the position of the maximum residual stress is dependent on the maximum pile-up around an indentation after unloading. The direction and components of residual stress can be correctly determined by the unique relationship between pile-up after unloading and biaxial residual stress. This conclusion has been verified by the experiment results in the residual stress measurements of a welded specimen with spherical indentation and x-ray diffraction methods. Meanwhile, the influences of friction between the object surface and the indenter, the material hardening exponent of the specimen, and the elastic deformation upon the residual stress are discussed.
It has not been established which specific measures of obesity might be most appropriate for predicting CVD risk in Asians. The objectives of the present study were to determine the associations of BMI, waist circumference (WC) and waist:height ratio (WHtR) with CVD risk factors and to evaluate the optimal cut-off values to define overweight or obesity in Chinese adults. Data collected from seven nationwide health examination centres during 2008 and 2009 were analysed. The BMI, WC and WHtR of 244 266 Chinese adults aged ≥ 20 years included in the study were measured. Logistic regression models were fit to evaluate the OR of each CVD risk factor according to various anthropometric indices. Receiver operating characteristic (ROC) analyses were conducted to assess the optimal cut-off values to predict the risk of diabetes, hypertension, dyslipidaemia and the metabolic syndrome. WHtR had the largest areas under the ROC curve for all CVD risk factors in both sexes, followed by WC and BMI. The optimal cut-off values were approximately 24·0 and 23·0 kg/m2 for BMI, 85·0 and 75·0 cm for WC, and 0·50 and 0·48 for WHtR for men and women, respectively. According to well-established cut-off values, BMI was found to be a more sensitive indicator of hypertension in both men and women, while WC and WHtR were found to be better indicators of diabetes and dyslipidaemia. A combination of BMI and central obesity measures was found to be associated with greater OR of CVD risk factors than either of them alone in both sexes. The present study demonstrated that WHtR and WC may be better indicators of CVD risk factors for Chinese people than BMI.
This paper investigates the trajectory tracking of a Stewart platform, which is a typical multi-input multi-output nonlinear system, with unmodeled dynamics, parameter uncertainties, friction, and unpredictable actuator faults. An adaptive vector sliding mode fault-tolerant control law is derived to ensure the system is insensitive to uncertainties and drive the state variable errors of the closed-loop system to converge to the origin. Moreover, novel adaptive laws are proposed to update the upper boundary of uncertainty according to the actual system state, which greatly reduces the chattering of sliding mode control. Furthermore, velocity signals are estimated by introducing a simple nonlinear observer, resulting in the proposed controller requiring position measurements only. Finally, numerical simulations illustrate the effectiveness of the proposed control scheme.
Human rhythmic movement is generated by central pattern generators (CPGs), and their application to robot control has attracted interest of many scientists. But the coupling relationship between the central nervous system and the CPG network with external inputs is still not unveiled. According to biological experiment results, the CPG network is controlled by the neural system; in other words, the interaction between the central nervous system and the CPG network can control human movement effectively. This paper offers a complex human locomotion model, which illustrates the coupling relationship between the central nervous system and the CPG network with proprioception. Based on Matsuoka's CPG model (K. Matsuoka, Biol. Cybern. 52(6), 367–376 (1985)), the stability and robustness of the CPG network are analyzed with external inputs. In order to simulate the coupling relationship, the Radial Basis Function (RBF) neural network is used to simulate the cerebral cortex, and the Credit-Assignment Cerebellar Model Articulation Controller algorithm is employed to realize the locomotion mode conversion. A seven-link biped robot is chosen to simulate the walking gait. The main discoveries include: (1) the output of a new CPG network, which is stable and robust, can be treated as proprioception. Proprioception provides the central nervous system with the information about all joint angles; (2) analysis on a new locomotion model reveals that the cerebral cortex can modulate CPG parameters, leading to adjustment in walking gait.
The spatially developing compressible plane mixing layer with a convective Mach number of 0.7 is investigated by direct numerical simulation. A pair of equal and opposite oblique instability waves is introduced to perturb the mixing layer at the inlet. The full evolution process of instability, including formation of -vortices and hairpin vortices, breakdown of large structures and establishment of self-similar turbulence, is presented clearly in the simulation. In the transition process, the flow fields are populated sequentially by -vortices, hairpin vortices and ‘flower’ structures. This is the first direct evidence showing the dominance of these structures in the spatially developing mixing layer. Hairpin vortices are found to play an important role in the breakdown of the flow. The legs of hairpin vortices first evolve into sheaths with intense vorticity then break up into small slender vortices. The later flower structures are produced by the instability of the heads of the hairpin vortices. They prevail for a long distance in the mixing layer until the flow starts to settle down into its self-similar state. The preponderance of slender inclined streamwise vortices is observed in the transversal middle zone of the transition region after the breakup of the hairpin legs. This predominance of streamwise vortices also persists in the self-similar turbulent region, though the vortices there are found to be relatively very weak. The evolution of both the mean streamwise velocity profile and the Reynolds stresses is found to have close connection to the behaviour of the large vortex structures. High growth rates of the momentum and vorticity thicknesses are observed in the transition region of the flow. The growth rates in the self-similar turbulence region decay to a value that agrees well with previous experimental and numerical studies. Shocklets occur in the simulation, and their formation mechanisms are elaborated and categorized. This is the first three-dimensional simulation that captures shocklets at this low convective Mach number.
The current study explored the effects of treadmill exercise intensity on functional recovery and hippocampal phospho-NR2B (p-NR2B) expression in cerebral ischemic rats, induced by permanent middle cerebral artery occlusion (MCAO) surgery.
Adult male Sprague-Dawley rats were randomly divided into four groups, including sham, no exercise (NE), low intensity training (LIT, v = 15 m/min), and moderate intensity training groups (MIT, v = 20 m/min). At different time points, the hippocampal expressions of p-NR2B and total NR2B were examined. In addition, neurological deficit score (NDS), body weight, and 2,3,5-triphenyltetrazolium chloride (TTC) staining were used to evaluate brain infarct volume as assessments of post-stroke functional recovery. In order to investigate the effect of exercise on survival, the mortality rate was also recorded.
The results showed that treadmill exercise significantly decreased hippocampal expression of p-NR2B but didn't change the total NR2B, compared to the NE group on the 3rd, 7th, and 14th days following MCAO surgery. The effect on changes in p-NR2B levels, body weight, and brain infarct volume were more significant in the LIT compared to the MIT group.
Discussion and Conclusion:
The current findings demonstrate that physical exercise can produce neuroprotective effects, in part by down-regulating p-NR2B expression. Furthermore, the appropriate intensity of physical exercise is critical for post-stroke rehabilitation.
Modern energy systems have been central to the development of human societies. They have perhaps been the single most important determinant of growth of our industrial societies and our modern economy. Unfortunately, they have also been a key driver of many of the negative environmental trends observed in the world today. For example, current energy systems are the predominant source of carbon dioxide (CO2) emissions, accounting for 84% of total global CO2 emissions and 64% of global greenhouse gas (GHG) emissions related to human activities. Past trends suggest that this percentage is likely to increase in the future if our energy needs continue to be met by fossil fuels.
The impact of GHG emissions on climate is arguably the most significant environmental impact associated with our energy systems, as the effects of such emissions are felt globally. However, these effects will not necessarily be equitable. Due to the realities of global and national economics, the areas that may suffer the greatest impacts from climate change may be those that have to date contributed the least in terms of GHG emissions. Our fossil fuel-based energy systems also emit substantial quantities of other atmospheric pollutants, for example sulphur dioxide (SO2), nitrogen oxides (NOx), primary particulate matter (PM), and non-methane volatile organic compounds (NMVOCs), which degrade air quality and cause damage to health and ecosystems through processes such as acidifi cation, eutrophication, and the formation of ground-level ozone (O3) and secondary PM. Biomass-based energy systems can also have substantial impacts on land and water resources.
Observational studies have indicated that soya food consumption is inversely associated with blood pressure (BP). Evidence from randomised controlled trials (RCT) on the BP-lowering effects of soya protein intake is inconclusive. We aimed to evaluate the effectiveness of soya protein intake in lowering BP. The PubMed database was searched for published RCT in the English language through to April 2010, which compared a soya protein diet with a control diet. We conducted a random-effects meta-analysis to examine the effects of soya protein on BP. Subgroup and meta-regression analyses were performed to explore possible explanations for heterogeneity among trials. Meta-analyses of twenty-seven RCT showed a mean decrease of 2·21 mmHg (95 % CI − 4·10, − 0·33; P = 0·021) for systolic BP (SBP) and 1·44 mmHg (95 % CI − 2·56, − 0·31; P = 0·012) for diastolic BP (DBP), comparing the participants in the soya protein group with those in the control group. Soya protein consumption significantly reduced SBP and DBP in both hypertensive and normotensive subjects, and the reductions were markedly greater in hypertensive subjects. Significant and greater BP reductions were also observed in trials using carbohydrate, but not milk products, as the control diet. Meta-regression analyses further revealed a significantly inverse association between pre-treatment BP and the level of BP reductions. In conclusion, soya protein intake, compared with a control diet, significantly reduces both SBP and DBP, but the BP reductions are related to pre-treatment BP levels of subjects and the type of control diet used as comparison.
The distribution of alloying elements and the corresponding structural evolution of Mn–Sb alloys in magnetic field gradients were investigated in detail. It was found that a high magnetic field gradient could control the distribution of solute element in the alloys during the solidification process and therefore resulted in the coexistence of both primary MnSb and Sb phases or the aggregation of the primary MnSb with a continuous change in morphology. The positions where these primary phases located depended on the direction of field gradient. The control of the solute element distribution by a high magnetic field gradient was realized through the magnetic buoyancy force that could drive the migration of Mn element in the melt, originating from the difference in the magnetic susceptibility between Mn and Sb. The effectiveness of this control depends on the alloy composition, specimen dimension, cooling rate, and |BdB/dz| value.
Objective. This paper assessed the potential of traditional Chinese medicine (TCM) preparations for using as environmentally acceptable and alternative commercial acaricides. Methods. 22 kinds of TCM, which contained abundant essential oils and showed insecticidal effects, were collected. Samples extracted with petroleum ether, ethyl acetate and methanol were tested against house dust mites Dermatophagoides farinae and their toxicity assessed. Results. The results showed that 3 TCM of Cinnamonum cassia, Eugenia caryophyllata and Pogostemon cablin have higher activity, and the parallel tests showed that the petroleum ether extract had higher activities (0·0046 mg/cm2, 0·005 mg/cm2 and 0·006 mg/cm2 respectively, 24 h, LD50) than the extracts of ethyl acetate and methanol. The acaricidal activity of the ethyl acetate extracts from C. cassia, P. cablin and Asarum sieboldii (0·00144 mg/cm2, 0·00347 mg/cm2 and 0·05521 mg/cm2 respectively, 24 h, LD50) were almost comparable to that of benzyl benzoate and dibutyl phthalate. However, the methanolic extracts of were less effective. Conclusions. This study shows the use of extracts with petroleum ether of C. cassia, P. cablin and E. caryophyllata as eco-friendly biodegradable agents for the control of the house dust mite.