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FM-to-AM conversion for angular filtering based on transmitted volume Bragg gratings (TBGs) is discussed. Simulation results show that a narrower spectral selectivity of TBGs led to stronger FM-to-AM conversion. Good angular selectivity and a wide bandwidth for the TBGs can be obtained by controlling the grating period and thickness. FM-to-AM conversion can be effectively suppressed and the distortion criterion for the filtered beam reduces to less than 5%. FM-to-AM conversion of TBGs is demonstrated in the ‘Shenguang’ facility, and the results are in good agreement with the simulation.
The output performances of a bidirectional ring amplifier with twin pulses are demonstrated. Compared to the extraction efficiency of 32% for single-pulse injection, the extraction efficiency of stored energy for twin-pulse injection with bidirectional propagation is increased to 60%. The maximum output energies of the twin pulses are 347 mJ and 351 mJ, and the output energy of a single pulse is only 373 mJ under the same amplifier operating conditions. The experimental results show that the bidirectional ring amplifier with twin pulses can achieve a higher extraction efficiency of stored energy at a lower operating fluence, and has potential applications in high-power and high-energy laser facilities.
A band-stop angular filter (BSF) based on hump volume Bragg gratings (HVBGs) is proposed. Band-stop filtering in a two-stage amplifier laser system is discussed and simulated. Simulation results show that small-scale self-focusing effects in the laser system can be effectively suppressed with the BSF due to the control of fast nonlinear growth in a specific range of spatial frequencies in the laser beam. Near-field modulation of the output beam from the laser system was decreased from 2.69 to 1.37 by controlling the fast nonlinear growth of spatial frequencies ranging from
with the BSF. In addition, the BSF can be used in a plug-and-play scheme and has potential applications in high-power laser systems.
Cast tungsten carbide is widely used to reinforce iron or steel substrate surface composites to meet the demands of harsh wear environments due to its extremely high hardness and excellent wettability with molten steel. Cast tungsten carbide particle/steel matrix surface composites have demonstrated great potential development in applications under the abrasive working condition. The thermal shock test was used to investigate the fatigue behavior of the composites fabricated by vacuum evaporative pattern casting technique at different temperatures. At elevated temperatures, the fatigue behavior of the composites was influenced by the oxidation of tungsten carbide, producing WO3. Thermodynamic calculations showed that the W2C in the tungsten carbide particle was oxidized at an initial temperature of approximately 570 °C. The relationship between oxidation and thermal fatigue crack growth was investigated, and the results suggested that oxidation would become more significant with increasing thermal shock temperature. These findings provide a valuable guide for understanding and designing particle/steel substrate surface composites.
Nanopore tuning via atomic layer deposition (ALD) is promising but its conformality on sub-10nm pores and its homogeneity over the whole porous network is still challenging, primarily due to the slow transport within the porous network. Conventional ALD process oftentimes falls into a dilemma: higher temperature and prolonged exposure/purge time are required to overcome the slow transport issue, but higher temperature will cause the instability of surface –OH groups and prolonged exposure/purge time will result in “over purge” at the surface vicinity, leading to another type of non-homogeneity. To resolve this issue, a new dual-stage exposure/purge ALD process was developed. Each exposure/purge step contains a longer exposure/purge stage and a shorter exposure/purge stage, where the longer stage ensures ideal exposure/purge for inner pores, and the shorter stage makes up the surface depletion for the outer pores. By doing so, we’ve been able to extend the ALD nanopore tuning to sub-10nm pores with excellent coating homogeneity and conformality.
The prevalence of overweight and obesity is growing rapidly in many countries. Socioeconomic inequalities might be important for this increase. The aim of this study was to determine associations of body mass index (BMI), overweight and obesity with educational level and marital status in Chinese twins. Participants were adult twins recruited through the Chinese National Twin Registry (CNTR), aged 18 to 79 years, and the sample comprised 10,448 same-sex twin pairs. Current height, weight, educational attainment, and marital status were self-reported. Regression analyses and structural equation models were conducted to evaluate BMI, overweight, and obesity associated with educational level and marital status in both sexes. At an individual level, both educational level and marital status were associated with higher BMI and higher risk of being overweight and obesity in men, while in women the effects of educational level on BMI were in the opposite direction. In within-Monozygotic (MZ) twin-pair analyses, the effects of educational level on BMI disappeared in females. Bivariate structural equation models showed that genetic factors and shared environmental confounded the relationship between education and BMI in females, whereas marital status was associated with BMI on account of significant positive unique environmental correlation apart in both sexes. The present data suggested that marital status and BMI were associated, independent of familiar factors, for both sexes of this study population, while common genetic and shared environmental factors contributed to education-associated disparities in BMI in females.
Using in situ transmission electron microscopy, we report the observation of the melting behavior of one-dimensional nanostructures of Sn with different length/width aspect ratios. The melting of small aspect-ratio nanowires (nanorods) results in the expansion of liquid Sn along both axial and radial directions with the tendency to form an isometric or spherical particle, thereby minimizing the total surface area. For nanowires with the length/width aspect ratio of ∼10.5, perturbation along the liquid stream causes an unstable necking phenomenon and the whole wire tends to shrink into a spherical particle. In contrast, Rayleigh instability sets in for the melting of the nanowires with the length/width aspect ratio as large as ∼21, which gives rise to necking and fragmentation of the wire into particles. The amorphous native surface oxide (SnOx) layer serves as a confinement tube and plays an important role in the melting induced morphological evolution of Sn nanowires. A thin SnOx layer is flexible with the ability to shrink or expand upon the flow of molten Sn. The increased rigidity for a thick SnOx surface layer kinetically suppresses bulging and necking formation in molten Sn nanowires.
Human adenovirus type 55 (HAdV-55) has recently caused multiple outbreaks. This study examined polymorphisms in CD46 to determine their involvement in HAdV-55 infection.
A total of 214 study subjects infected with HAdV-55 were included in our study. The study subjects were divided into those with silent infections (n=91), minor infections (n=85), and severe infections (n=38). Ten single nucleotide polymorphisms (SNPs) from CD46 were examined.
Compared with the AA genotype, the TT genotype at rs2724385 (CD46, A/T) was associated with a protective effect against disease occurrence, with an odds ratio (95% confidence interval) of 0.20 (0.04-0.97) (P=0.038). There were no significant differences between the patients with minor and severe infection and those who had silent HAdV-55 infection in the other CD46 SNPs. We next compared the polymorphisms of these genes according to disease severity in HAdV-55-infected patients with clinical symptoms. The results showed that there were no significant differences between minor infections and severe infections.
Our results suggested that the CD46 SNP at rs2724385 is associated with the occurrence of disease in HAdV-55-infected patients. A much larger number of samples is required to understand the role of CD46 polymorphisms in the occurrence and progression of infection by HAdV-55. (Disaster Med Public Health Preparedness. 2018;12:427–430)
To explore the 3-tiered treatment model for medical treatment after an earthquake.
Based on the practices of the national emergency medical rescue services in the Lushan earthquake zone, the 3-tiered treatment classification approach was retrospectively reviewed.
Medical rescue teams assembled and reported quickly to the disaster areas after the earthquake. The number of injured people had reached 25,176 as of April 30; of these, 18,611 people were treated as outpatients, 6565 were hospitalized, and 977 were seriously or severely injured.
The 3-tiered treatment model was the main approach used by rescue services after the Lushan earthquake. Primary and secondary treatments were of the highest importance and formed the basis of the Lushan model of earthquake rescue and treatment. (Disaster Med Public Health Preparedness. 2018; 12: 301–304)
The objective of this study was to build a database to collect infectious disease information at the scene of a disaster through the use of 128 epidemiological questionnaires and 47 types of options, with rapid acquisition of information regarding infectious disease and rapid questionnaire customization at the scene of disaster relief by use of a personal digital assistant (PDA).
SQL Server 2005 (Microsoft Corp, Redmond, WA) was used to create the option database for the infectious disease investigation, to develop a client application for the PDA, and to deploy the application on the server side. The users accessed the server for data collection and questionnaire customization with the PDA.
A database with a set of comprehensive options was created and an application system was developed for the Android operating system (Google Inc, Mountain View, CA). On this basis, an infectious disease information collection system was built for use at the scene of disaster relief. The creation of an infectious disease information collection system and rapid questionnaire customization through the use of a PDA was achieved.
This system integrated computer technology and mobile communication technology to develop an infectious disease information collection system and to allow for rapid questionnaire customization at the scene of disaster relief. (Disaster Med Public Health Preparedness. 2017;11:668–673)
To determine dynamic changes in clinical characteristics by examining an outbreak of adenovirus infection that occurred from December 20, 2012, to February 25, 2013, in Tianjin, China.
Active surveillance for febrile respiratory illnesses was conducted, and medical records of patients were collected. Real-time quantitative polymerase chain reaction and sequencing were used for pathogen identification and viral genome study, respectively. Student’s t-test was used to compare the mean values of normally distributed continuous variables. Mann-Whitney U or Kruskal-Wallis tests were used if continuous variables were not normally distributed. Pearson’s chi-square test or Fisher’s exact test was used to compare categorical variables.
The outbreak was sourced from the index case diagnosed as the common cold on December 20, 2012; a total of 856 cases were reported in the following 66 days. The pathogen was identified as human adenovirus (HAdV) 55. The symptoms manifested differently in severe and mild cases. Routine blood examinations, liver function indexes, and heart function indexes showed different dynamic patterns over time in hospitalized patients.
Clinical characteristics and laboratory examinations may reveal unique patterns over the course of HAdV-55 infection. (Disaster Med Public Health Preparedness. 2018;12:464–469)
This study aimed to comprehensively evaluate factors that influence the likelihood of syphilis infection from risk-taking behaviours and medical conditions. A retrospective case-control study was conducted by enrolling 664 syphilis inpatients (excluding 11 congenital syphilis patients) and 800 sex- and age-matched controls. Medical histories, clinical data and patient interview data were collected and subjected to logistic regression analyses. The prevalence of syphilis in the study population was 3·9% (675/17 304). By univariate analysis, syphilis infection was associated with migration between cities, marital status, smoking, reproductive history, hypertension, elevated blood urea nitrogen (BUN) and infection with hepatitis B virus (HBV) (P < 0·05). A high rate of syphilis-HBV co-infection was observed in HIV-negative patients and further research revealed an association between syphilis and specific HBV serological reactivity. Syphilis was also associated with the frequency, duration and status of tobacco use. Multivariate analysis indicated that syphilis infection was independently associated with migration between cities [adjusted odds ratio (aOR) 1·368, 95% confidence interval (CI) 1·048–1·785], current smoking (aOR 1·607, 95% CI 1·177–2·195), elevated BUN (aOR 1·782, 95% CI 1·188–2·673) and some serological patterns of HBV infection. To prevent the spread of infectious diseases, inpatients and blood donors should be tested for HIV, syphilis, HBV and HCV simultaneously.
This study examined the genetic and environmental effects on variances in weight, height, and body mass index (BMI) under 18 years in a population-based sample from China. We selected 6,644 monozygotic and 5,969 dizygotic twin pairs from the Chinese National Twin Registry (CNTR) aged under 18 years (n = 12,613). Classic twin analyses with sex limitation were used to estimate the genetic and environmental components of weight, height, and BMI in six age groups. Sex-limitation of genetic and shared environmental effects was observed, especially when puberty begins. Heritability for weight, height, and BMI was low at 0–2 years old (less than 20% for both sexes) but increased over time, accounting for half or more of the variance in the 15–17 year age group for boys. For girls, heritabilities for weight, height and BMI was maintained at approximately 30% after puberty. Common environmental effects on all body measures were high for girls (59–87%) and presented a small peak during puberty. Genetics appear to play an increasingly important role in explaining the variation in weight, height, and BMI from early childhood to late adolescence, particularly in boys. Common environmental factors exert their strongest and most independent influence specifically in the pre-adolescent period and more significantly in girls. These findings emphasize the need to target family and social environmental interventions in early childhood years, especially for females. Further studies about puberty-related genes and social environment are needed to clarify the mechanism of sex differences.
Twins reared apart provide a fascinating experiment to distinguish genetic from environmental influences. However, there is as yet no broad report on distribution of twins reared apart, especially in the Chinese population. In this study, information on 18,295 volunteer twin pairs of all age groups was compiled in nine provinces or cities of China, and questionnaires were used for zygosity determination. It was discovered that twins reared apart from 0 to 10 years of age accounted for 2.2% of all twin interviewees, with the proportion of this 0–10 group separated before 1, 2, and 5 years old, accounting for 65.3%, 76.1%, and 91.3%, respectively. The proportion of twins reared apart is not significantly related to zygosity or gender, but it is related to region and twin age. As the age of twins lowers, the proportion of those reared apart gradually decreases. Twins reared apart will become rarer in the future and therefore should be cherished as a resource.
Laser-induced vibrational excitation of ethylene molecules was integrated to the CVD diamond deposition process for an in-depth understanding of the energy coupling path in chemical reactions and an alternative method to enhance the diamond deposition. On- and off-resonance excitations of ethylene molecules were achieved via tuning the incident laser wavelengths centered at 10.532 µm. With the same amount of laser power absorbed, the chemical reaction is highly accelerated with on-resonance vibrational excitation whereas energy coupling with off-resonance excitations was less efficient in influencing the combustion process. The diamond deposition rate was enhanced by a factor of 5.7 accompanied with an improvement of diamond quality index with the on-resonance excitation at 10.532 μm. The measured flame temperature demonstrated that the resonant vibrational excitation was an efficient route for coupling energy into the reactant molecules and steering the combustion process.
There is growing concern in West Africa about the spread of the Ebola hemorrhagic fever virus. With the increasing global public health risk, a coordinated international response is necessary. The Chinese government is prepared to work in collaboration with West African countries to assist in the containment and control of the epidemic through the contribution of medical expertise and mobile laboratory testing teams. Nationally, China is implementing prevention programs in major cities and provinces, the distribution of Ebola test kits, and the deployment of a new national Ebola research laboratory. (Disaster Med Public Health Preparedness. 2015;0:1-2)
In this work, we compiled 604 blazars with available core-dominance parameter, out of which 149 blazars are known to have γ-ray emissions. We compared the logR between the 149 Fermi-detected blazars (FDB) and the rest non-Fermi-detected blazars (non-FDB), and found that the average values are < logR > = 1.12 ± 0.88 for FDBs and < logR > = 0.05 ± 0.94 for non-FDBs. A K-S test shows that the probability for the distributions of FDB and non-FDB to come from the same parent distribution is P = 2.38 × 10−7. We also investigated the correlation between the core-dominance parameters and the γ-ray emission variability index (VI) for 125 FDBs (45 BLs and 79 FSRQs), and found that there is a tendency for VI to increase with the core-dominance parameter for 79 FSRQs, but there is no such tendency for 46 BLs.
A support vector machine (SVM) method is applied to select K giant stars directly from the spectral features of LAMOST spectra. The performance of the algorithm is assessed using the MILES library. It shows that the completeness of the K giant stars is 87% with only about 6% dwarf contamination. This allows us to select 18,013 K giant stars at |b|>20° and 38,108 at |b|<20° from LAMOST pilot survey data.