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 study the evolution of unidirectional water waves from a randomly forced input condition with uncorrelated Fourier components. We examine the kurtosis of the linearised free surface as a convenient proxy for the probability of a rogue wave. We repeat the laboratory experiments of Onorato et al. (Phys. Rev. E, vol. 70, 2004, 067302), both experimentally and numerically, and extend the parameter space in our numerical simulations. We consider numerical simulations based on the modified nonlinear Schrödinger equation and the fully nonlinear water wave equations, which are in good agreement. For low steepness, existing analytical models based on the nonlinear Schrödinger equation (NLS) are found to be accurate. For cases which are steep or have very narrow bandwidths, these analytical models over-predict the rate at which excess kurtosis develops. In these steep cases, the kurtosis in both our experiments and numerical simulations peaks before returning to an equilibrium level. Such transient maxima are not predicted by NLS-based analytical models. Above a certain threshold of steepness, the steady-state value of kurtosis is primarily dependent on the spectral bandwidth. We also examine how the average shape of extreme events is modified by nonlinearity over the evolution distance, showing significant asymmetry during the initial evolution, which is greatly reduced once the spectrum has reached equilibrium. The locations of the maxima in asymmetry coincide approximately with the locations of the maxima in kurtosis.
Folate status for women during early pregnancy has been investigated, but data for women during mid-pregnancy, late pregnancy, or lactation are sparse or lacking. Between May and July 2014, we conducted a cross-sectional study in 1211 pregnant and lactating women from three representative regions in China. Approximately 135 women were enrolled in each stratum by physiologic periods (mid-pregnancy, late pregnancy, or lactation) and regions (south, central, or north). Plasma folate concentrations were measured by microbiological assay. The adjusted medians (interquartile ranges [IQR]) of folate concentration decreased from 28.8 (19.9 – 38.2) nmol/L in mid-pregnancy to 18.6 (13.2 – 26.4) nmol/L in late pregnancy, and to 17.0 (12.3 – 22.5) nmol/L in lactation (P for trend <0.001). Overall, lower folate concentrations were more likely to be observed in women residing in northern region, with younger age, higher pre-pregnancy BMI, lower education or multiparity, and in lactating women underwent a caesarean delivery or breastfed exclusively. In total, 380 (31.4%) women had a suboptimal folate status (folate concentration <13.5 nmol/L). Women of being at late pregnancy and lactation, residing in northern region, having multiparity and low education level had a higher risk of suboptimal folate status, while those with older age had a lower risk. In conclusion, maternal plasma folate concentrations decreased as pregnancy progressed, and influenced by geographic region and maternal social-demographic characteristics. Future studies are warranted to assess the necessity of folic acid supplementation during later pregnancy and lactation especially for women at a higher risk of folate depletion.
The diet impact on metabolic syndrome(MetS) and cardiovascular diseases has been investigated widely, but few studies investigated the association between dietary patterns(DPs) and the the predicted cardiovascular disease, derived from reduced-rank regression (RRR). The objectives of this study were to derive DPs using RRR and principal component analysis (PCA), and investigate their associations with MetS and estimated 10-year atherosclerotic cardiovascular disease (ASCVD). We used the baseline dataset from the Xinjiang multi-ethnic cohort study in China, collected from June 2018 to may 2019. A total of 14982 subjects aged 35-74 years from Urumqi, Huo Cheng, and Mo Yu were included in the analysis. The 10-year ASCVD risk was estimated using the Chinse ASCVD risk equations. The associations of DPs with MetS and 10-year ASCVD were determined using multivariable logistic regression models. In Urumqi and Mo yu, the increased RRR DP score was associated with a higher odds ratio (OR) of having the MetS and with a higher OR of elevated 10-year ASCVD risk. However, Only the first DP determined by PCA in Urumqi were inversely associated with MetS and elevated 10-year ASCVD risk. The prevalence of MetS and elevated ASCVD risk in urban population is higher than that in rural areas. Our results may help nutritionists develop more targeted dietary strategies to prevent MetS and ASCVD in different regions in China.
To investigate risk factors and psychological stress of health care workers (HCWs) with COVID-19 in a non-frontline clinical department.
Data of 2 source patients and all HCWs with infection risk were obtained in a department in Wuhan from January to February 2020. A questionnaire was designed to evaluate psychological stress of COVID-19 on HCWs.
The overall infection rate was 4.8% in HCWs. 10 of 25 HCWs who contacted with 2 source patients were diagnosed with confirmed COVID-19 (8/10) and suspected COVID-19 (2/10). Other 2 HCWs were transmitted by other patients or colleagues. Close care behaviours included physical examination (6/12), life nursing (4/12), ward rounds (4/12), endoscopic examination (2/12). Contacts fluctuated from 1 to 24 times and each contact was short (8.1 min ± 5.6 min). HCWs wore surgical masks (11/12), gloves (7/12), and isolation clothing (3/12) when providing medical care. Most HCWs experienced a mild course with 2 asymptomatic infections, taking 9.8 days and 20.9 days to obtain viral shedding and clinical cure, respectively. Psychological stress included worry (58.3%), anxiety (83.3%), depression (58.3%), and insomnia (58.3%).
Close contact with COVID-19 patients and insufficient protection were key risk factors. Precaution measures and psychological support on COVID-19 is urgently required for HCWs.
The present study aimed to investigate the association of the Chinese visceral adiposity index (CVAI) and its 6-year change with hypertension risk and compare the ability of CVAI and other obesity indices to predict hypertension based on the Rural Chinese Cohort Study. Study participants were randomly recruited by a cluster sampling procedure, and 10 304 participants ≥18 years were included. Modified Poisson regression was used to derive adjusted relative risks (RR) and 95 % CI. We identified 2072 hypertension cases during a median of 6·03 years of follow-up. The RR for the highest v. lowest CVAI quartile were 1·29 (95 % CI 1·05, 1·59) for men and 1·53 (95 % CI 1·22, 1·91) for women. Per-sd increase in CVAI was associated with hypertension for both men (RR 1·09, 95 % CI 1·02, 1·16) and women (RR 1·14, 95 % CI 1·06, 1·22). Also, the area under the receiver operating characteristic curve value for hypertension was higher for CVAI than the four other obesity indices for both sexes (all P < 0·05). Finally, per-sd increase in CVAI change was associated with hypertension for both men (RR 1·26, 95 % CI 1·16, 1·36) and women (RR 1·23, 95 % CI 1·15, 1·30). Similar results were observed in sensitivity analyses. CVAI and its 6-year change are positively associated with hypertension risk. CVAI has better performance in predicting hypertension than other visceral obesity indices for both sexes. The current findings suggest CVAI as a reliable and applicable predictor of hypertension in rural Chinese adults.
In higher plants, fertilization induces many structural and physiological changes in the fertilized egg that reflect the transition from the haploid female gamete to the diploid zygote – the first cell of the sporophyte. After fusion of the egg nucleus with the sperm nucleus, many molecular changes occur in the zygote during the process of zygote activation during embryogenesis. The zygote originates from the egg, from which some pre-stored translation initiation factors transfer into the zygote and function during zygote activation. This indicates that the control of zygote activation is pre-set in the egg. After the egg and sperm nuclei fuse, gene expression is activated in the zygote, and paternal and maternal gene expression patterns are displayed. This highlights the diversity of zygotic genome activation in higher plants. In addition to new gene expression in the zygote, some genes show quantitative changes in expression. The asymmetrical division of the zygote produces an apical cell and a basal cell that have different destinies during plant reconstruction; these destinies are determined in the zygote. This review describes significant advances in research on the mechanisms controlling zygote activation in higher plants.
Eurasian steppes experienced frequent cultural transfers, human migration, and diffusion of techniques during the Bronze Age. The Hami Oasis is one of the most dynamic areas and has attracted multiple cultural flows. It is an important area that connects various routes of the Tianshan Corridor with the Hexi Corridor in western China. The Tianshanbeilu cemetery is the largest Bronze Age cemetery in Hami. Thirty-seven new radiocarbon dates allowed us to establish a new and more accurate chronology for Tianshanbeilu. Our results showed that the Tianshanbeilu cemetery was used from approximately 2022–1802 cal BC and remained in use from 1093–707 cal BC. This indicates that Tianshanbeilu is the earliest and longest-used known cemetery in eastern Xinjiang. By incorporating the typology of artifacts and stratigraphic relationships, the development of the Tianshanbeilu cemetery was divided into four phases. The first phase was from 2011–1672 cal BC, the second phase was from 1660–1408 cal BC, the third phase was from 1385–1256 cal BC, and the fourth phase was from 1214–1029 cal BC.
To reveal the thermal shock resistance of double-layer thermal barrier coatings (TBCs), two types of TBCs were prepared via atmospheric plasma spraying, i.e., Gd2Zr2O7/yttria-stabilized zirconia (GZ/YSZ) TBCs and La2Zr2O7 (LZ)/YSZ TBCs, respectively. Subsequently, thermal cycling tests of the two TBCs were conducted at 1100 °C and their thermal shock resistance and failure mechanism were comparatively investigated through experiments and the finite element method. The results showed that the thermal shock failure of the two TBCs occurred inside the top ceramic coating. However, the GZ/YSZ TBCs had longer thermal cycling life. It was the mechanical properties of the top ceramic coating, and the thermal stresses arising from the thermal mismatch between the top ceramic coating and the substrate that determined the thermal cycling life of the two TBCs together. Compared with the LZ layer in the LZ/YSZ TBCs, the GZ layer in the GZ/YSZ TBCs had smaller elastic modulus, larger fracture toughness, and smaller thermal stresses, which led to the higher crack propagation resistance and less spallation tendency of the GZ/YSZ TBCs. Therefore, the GZ/YSZ TBCs exhibited superior thermal shock resistance to the LZ/YSZ TBCs.
In this paper, dual-band and tri-band bandpass filters (BPFs) with fully independent and controllable passbands based on multipath-embedded resonators are presented. The dual-band BPF consists of two double open-ended stub-loaded terminal-shorted resonators (DOESL-TSRs) with a common via-hole connected along the symmetric plane of the filter. Based on DOESL-TSRs, a triple open-ended stub-loaded terminal-shorted resonator (TOESL-TSR) is proposed in the design of tri-band BPFs. The resonant characteristics of DOESL-TSR/TOESL-TSR are analyzed by the numerical calculation method. The measured results of the dual-band BPF show that the center frequencies (CFs) are located at 2.595 and 5.75 GHz, respectively, with 3 dB fraction bandwidth (FBWs) of 15 and 12.8%. The measured CFs of the tri-band BPF are located at 2.545, 3.775, and 5.95 GHz, respectively, with 3 dB FBWs of 9.8, 9.3, and 5.5%. Both of the filters exhibit the merits of fully independent and controllable passbands, high selectivity, and compact size.
No studies have reported on how to relieve distress or relax in medical health workers while wearing medical protective equipment in coronavirus disease 2019 (COVID-19) pandemic. The study aimed to establish which relaxation technique, among six, is the most feasible in first-line medical health workers wearing medical protective equipment.
This was a two-step study collecting data with online surveys. Step 1: 15 first-line medical health workers were trained to use six different relaxation techniques and reported the two most feasible techniques while wearing medical protective equipment. Step 2: the most two feasible relaxation techniques revealed by step 1 were quantitatively tested in a sample of 65 medical health workers in terms of efficacy, no space limitation, no time limitation, no body position requirement, no environment limitation to be done, easiness to learn, simplicity, convenience, practicality, and acceptance.
Kegel exercise and autogenic relaxation were the most feasible techniques according to step 1. In step 2, Kegel exercise outperformed autogenic relaxation on all the 10 dimensions among the 65 participants while wearing medical protective equipment (efficacy: 24 v. 15, no space limitation: 30 v. 4, no time limitation: 31 v. 4, no body position requirement: 26 v. 4, no environment limitation: 30 v. 11, easiness to learn: 28 v. 5, simplicity: 29 v. 7, convenience: 29 v. 4, practicality: 30 v. 14, acceptance: 32 v. 6).
Kegel exercise seems a promising self-relaxation technique for first-line medical health workers while wearing medical protective equipment among COVID-19 pandemic.
We report a family cluster of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involving five patients in a family cluster in Dazhou, China, including the epidemiological, clinical, laboratory and radiological findings. Three-generation transmission was observed. Through epidemiological investigation, we observed asymptomatic transmission to a cohabiting family member, as well as person-to-person transmission of SARS-CoV-2 outside Wuhan city. The asymptomatic transmission demonstrated here provides evidence that there could be a greater risk of Coronavirus Disease 2019 (COVID-19) spread. This cluster also demonstrated that COVID-19 is transmissible during the incubation period of an asymptomatic person. Early isolation and treatment, stressing prevention of cluster outbreaks, could help prevent further spread of the epidemic.
The objective of the present study was to elucidate whether resveratrol could facilitate the survival of boar sperm during liquid preservation and fast cooling processes. Boar semen were diluted with Modena extender containing different concentrations of resveratrol. Sperm motility was evaluated by visual estimation. Membrane integrity, acrosome integrity and mitochondrial membrane potentials were measured by SYBR-14/PI, FITC-PNA and JC-1 staining, respectively. Moreover, the levels of reactive oxygen species (ROS), malonaldehyde (MDA) and total antioxidant capacity (T-AOC) were measured using commercial assay kits. B-cell lymphoma protein-2 (BCL2) content was determined by western blotting. During liquid preservation at 17oC, the addition of 50 μM resveratrol to the Modena extender significantly improved sperm motility, membrane integrity, acrosome integrity, and sperm mitochondrial membrane potentials. Similar results were also observed in the 150 μM resveratrol group during the fast cooling process. Furthermore, addition of resveratrol led to a decrease of ROS and MDA, and an increase in the content of T-AOC and BCL2. These observations suggest that addition of resveratrol to Modena extender protects boar sperm against oxidative stress. The optimal concentrations of resveratrol are 50 μM and 150 μM during liquid preservation and fast cooling process, respectively.
The storage root of alligatorweed [Alternanthera philoxeroides (Mart.) Griseb.] growing in terrestrial habitats is an important metamorphic organ for its propagation, overwintering, and spread. However, the regulatory mechanism adventitious root expansion to form storage roots is still unclear. To reveal the changes accompanying the root-swelling process, we quantified sugar, soluble protein, and phytohormone content in adventitious and storage roots. Results demonstrated that sucrose, fructose, and soluble protein increased in storage roots, whereas abscisic acid (ABA), indoleacetic acid (IAA), brassinosteroid (BR), gibberellin, jasmonic acid, and cytokinin (trans-zeatin [tZ] and isopentenyladenine [iP] and the corresponding ribosides tZR and iPR). tZ-type (tZR and tZ) content decreased, suggesting the involvement of sugars and hormones in the formation of storage roots. To further reveal the molecular basis of A. philoxeroides’s ability to form storage roots and provide candidate genes for molecular function analyses, we assembled a de novo transcriptome of A. philoxeroides based on four sets of RNA-sequencing data. According to functional annotation and expression profiling, 42 unigenes involved in sucrose synthesis and hydrolysis were identified, in addition to 70, 58, and 78 unigenes in ABA, BR, and IAA signal transduction, respectively. The quantitative reverse transcriptase polymerase chain reaction analysis revealed 21 unigenes involved in sugar metabolism and hormone signal transduction were differentially expressed during the formation of storage roots. These results revealed metabolic changes during the formation of storage roots and provide candidate genes involved in sugar and phytohormone metabolism in A. philoxeroides.
During recent stratigraphical and micropaleontological investigations of the Gulupu section in Tüna, Yadong, of the Eocene Zhepure Formation, numerous holoplanktonic mollusks (pteropods) were recovered. Four species, assignable to two genera of pteropods (including Limacina yadongensis new species) were systematically described and illustrated, and a gastropod-bivalve biofacies was identified. This is the first report of Eocene (Ypresian) pteropods in southern Tibet; the same stratum also yields many other neritic faunas. The data presented in this study suggest that a semi-closed restricted gulf in the Tüna area existed and the occurrence of pteropods in Tüna may indicate transport from more open, deep water by oceanic currents during early Eocene. Based on the analysis of paleogeographical distribution of pteropods, it indicates that a Tethys seaway existed during the early Eocene (Ypresian).
To develop an equation that can estimate the 24-h urinary Na excretion by using casual spot urine specimen for older hypertensive participants in rural Ningxia and further to compare with the INTERSALT method, Kawasaki method and Tanaka method.
Older hypertensive participants in rural Ningxia provided their casual spot urine samples and 24-h urine samples between January 2015 and February 2017. Sex-specific equation was developed using linear forward stepwise regression analysis. Model fit was assessed using adjusted R2. Approximately half of all participants were randomly selected to validate the equation. Mean differences, intraclass correlation coefficients and Bland–Altman plots were used to evaluate the performance of all methods.
Pingluo County and Qingtongxia County in Ningxia Hui Autonomous Region, China.
Older hypertensive participants in rural Ningxia.
Totally, 807 of 1120 invited participants provided qualified 24-h urine samples and spot urine samples. There was no statistical difference comparing the laboratory-based method against the new method and the INTERSALT method, while Kawasaki method had the largest bias with a mean difference of 40·81 g/d (95 % CI 39·27, 42·35 g/d). Bland–Altman plots showed similar pattern of the results.
The INTERSALT method and the new equation have the potential to estimate the 24-h urinary Na excretion in this study population. However, the extrapolation of the results to other population needs to be careful. Future research is required to establish a more reliable method to estimate 24-h urinary Na excretion.
Reduced graphene oxide supported titanium dioxide (GO/TiO2) heterojunction composites as highly active photocatalysts were synthesized via simple ultrasonic mixing and hydrothermal reaction using TiCl3 and GO as precursors. Their structure and morphology were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, UV-vis spectroscopy, and thermogravimetic analysis. The GO/TiO2 heterojunction composites were used to degrade methyl orange (MO). The adsorption and photocatalytic degradation rate of the prepared GO/TiO2 composites increased by nearly three times compared with that of pristine TiO2 or GO, which reached up 90%, to degrade MO after 4 h, which provides a simple method to obtain photocatalytic materials.