Beam Steering Using Momentum-Reconfigurable Goubau Meta-Line Radiators.

Spoof/designer surface plasmon polaritons (SPP) and Goubau line belong to the same category of single-conductor surface waveguide. They feature easy integration and high field confinement capability, and hence are good candidates for wave guiding and radiating at terahertz frequencies. Here, we propose a momentum-reconfigurable Goubau meta-line radiator that is capable of digitally steering its beam at a fixed frequency, in contrast to conventional SPP or Goubau line radiators relying on changing frequencies to steer beams. By periodically loading switchable meta-lines with ON and OFF states along the Goubau line, the modulation period and hence the momentum of Goubau line radiators can be dynamically controlled. The proposed Goubau line radiator is able to steer the main beam at a given frequency by independently switching ON or OFF each unit cell. As a proof of concept, we use line connection and disconnection to mimic ON and OFF state of the switch, respectively. Several radiators, representing different switching coding combinations, are fabricated and experimentally validated. Although this momentum-reconfigurable Goubau meta-line radiator is demonstrated at microwave frequency, it can be easily extended to terahertz frequencies.

Random Combinatorial Gradient Metasurface for Broadband, Wide-Angle and Polarization-Independent Diffusion Scattering.

This paper proposes an easy, efficient strategy for designing broadband, wide-angle and polarization-independent diffusion metasurface for radar cross section (RCS) reduction. A dual-resonance unit cell, composed of a cross wire and cross loop (CWCL), is employed to enhance the phase bandwidth covering the 2π range. Both oblique-gradient and horizontal-gradient phase supercells are designed for illustration. The numerical results agree well with the theoretical ones. To significantly reduce backward scattering, the random combinatorial gradient metasurface (RCGM) is subsequently constructed by collecting eight supercells with randomly distributed gradient directions. The proposed metasurface features an enhanced specular RCS reduction performance and less design complexity compared to other candidates. Both simulated and measured results show that the proposed RCGM can significantly suppress RCS and exhibits broadband, wide-angle and polarization independence features.

Continuous Beam Steering Through Broadside Using Asymmetrically Modulated Goubau Line Leaky-Wave Antennas.

Goubau line is a single-conductor transmission line, featuring easy integration and low-loss transmission properties. Here, we propose a periodic leaky-wave antenna (LWA) based on planar Goubau transmission line on a thin dielectric substrate. The leaky-wave radiations are generated by introducing periodic modulations along the Goubau line. In this way, the surface wave, which is slow-wave mode supported by the Goubau line, achieves an additional momentum and hence enters the fast-wave region for radiations. By employing the periodic modulations, the proposed Goubau line LWAs are able to continuously steer the main beam from backward to forward within the operational frequency range. However, the LWAs usually suffer from a low radiation efficiency at the broadside direction. To overcome this drawback, we explore both transversally and longitudinally asymmetrical modulations to the Goubau line. Theoretical analysis, numerical simulations and experimental results are given in comparison with the symmetrical LWAs. It is demonstrated that the asymmetrical modulations significantly improve the radiation efficiency of LWAs at the broadside. Furthermore, the measurement results agree well with the numerical ones, which experimentally validates the proposed LWA structures. These novel Goubau line LWAs, experimentally demonstrated and validated at microwave frequencies, show also great potential for millimeter-wave and terahertz systems.

An epidemiology study of bronchial asthma in the Li ethnic group in China.

OBJECTIVE: To investigate the prevalence and risk factors of bronchial asthma in the Li ethnic group in Hainan, China. METHODS: This study employed a stratified random sample design using custom-designed questionnaires. Subjects with asthma-like symptoms were first identified by two rounds of surveys and then confirmed by respiratory physicians using pulmonary function test, bronchial dilation test and challenge test. Demographic data, information on family history of asthma, history of allergies, smoking habits, domestic cooking fuel and other potential risk factors were collected. Logistic regression was performed to evaluate risk factors for asthma. RESULTS: The prevalence of asthma in the Li ethnic group was 3.38%, much higher than the national average level in China. Aging, agriculture industry (the rubber industry in particular), rural residence, family history of asthma, history of allergies, cold air, inhalation of dust and irritant gases, smoking, domestic cooking fuel and living environment were associated with increased risk of asthma. CONCLUSIONS: The high prevalence of asthma in the Li ethnic group highlights the importance of asthma prevention and treatment in this population. Risk factors indentified in this study warrant special attention. Elevating public awareness about asthma in local communities will benefit the prevention of the disease.

[Prevalence and risk factors of bronchial asthma among Li nationality in Hainan province].

OBJECTIVE: To study the risk factors of bronchial asthma of Li nationality in Hainan. METHODS: A total of 13 050 subjects of Li nationality were selected by random unequal ratio stratified cluster sampling method from southern, central and western part of Hainan and investigated with Hainan Epidemiological Asthma Survey Questionnaire of Li Nationality. There were 441 cases of bronchial asthma, and 1296 cases of control that were sampled by random number table method. The logistic regression method was used to analyze risk factors. RESULTS: The asthma prevalence of Li nationality in Hainan was 3.38%(441/13 050). The main risk factors of asthma were family asthma (OR = 4.323, 95%CI = 3.259 - 5.735), hypersensitiveness (OR = 7.775, 95%CI = 5.686 - 10.632), smoking (OR = 1.494, 95%CI = 1.174 - 1.902), cooking fuels and living environment. Cold air change (OR = 1.604, 95%CI = 1.286 - 2.001) and respirable dust or irritant gas (OR = 2.123, 95%CI = 1.702 - 2.648) were the important incentives. CONCLUSION: The main risk factors of asthma among Li nationality were family asthma, hypersensitiveness, smoking, cooking fuels by means of fuel oil, hay or wood, living environment by means of couch grass room and human-livestock mix live, cold air change, respirable dust or irritant gas.

[Prevalence survey on bronchial asthma of Li nationality in Hainan from 2003 to 2007].

OBJECTIVE: To learn the prevalence rate and distribution of bronchial asthma of Li nationality in Hainan by epidemiological survey so as to provide rationales for preventing and treating asthma. METHODS: A total of 13 050 subjects of Li nationality in Hainan were investigated by random sampling of stratified cluster method with an unequal ratio according to the medical records, physical signs and symptoms and pulmonary function tests. Then the prevalence was analyzed according to different population characteristics. RESULTS: The prevalence rate of asthma was 3.38% for Li nationality in Hainan. And it increased with an advancing age. It was much higher in agricultural population (4.08%) than that in cultivation and commercial populations (2.52% and 1.97%, P < 0.01). The asthma prevalence rate was in the highest at 4.62% in rubber workers. And it was much higher in rural areas than that in urban areas (3.85% vs 2.63%, P < 0.01). CONCLUSIONS: The epidemiological distribution of asthma of Li nationality in Hainan has been determined. And asthma remains a severe problem locally. The efforts of preventing and treating asthma and its education should be strengthened.

Health risk evaluation for the inhabitants of a typical mining town in a mountain area, South China.

A previous study investigated metal contamination in farmland and the air in a typical mining town of Guangxi, South China. In this study, the health risks associated with exposure to this contamination that were evaluated for the following routes of exposure are reported: inhalation, dermal contact, ingestion of dust, and ingestion of homegrown vegetables. The findings demonstrated that the inhabitants were at high risk for noncancer effects posed by some of the metals. The total hazard index (THI) of all the pathways was 145 for adults and 560 for children, which were far higher than the normative level 1. The noncancer risk mainly came from air PM(10) pollution through inhalation and ingestion routes of exposure. However, vegetable ingestion also made a noticeable contribution to HI of about 7 for adults and 22 for children. The metals that posed the greatest noncancer risks were Mn for inhalation, and ingestion of dust and vegetables. The total cancer risks of the inhabitants were 1 x 10(-1) (adult) and 3 x 10(-1) (child), which far exceeded the acceptable carcinogen risk of 10(-4) approximately 10(-6) for regulatory purposes. The cancer risk in the village is mainly (97%) associated with As exposure by inhalation and ingestion of dust. However, consumption of vegetables is also associated with a significant cancer risk of up to 2 x 10(-3) for adults and 8 x 10(-3) for children. The cancers associated with this exposure are estimated to be lung cancer and skin cancer. Air particulate-matter pollution was the main source of noncancer risk and cancer risk and originated from vehicular transport of ore through the community. The risk could be tested by a specifically designed epidemiological study.

[Association of polymorphisms of N372H in BRCA2 gene and 135G/C in RAD51 gene and breast cancers].

OBJECTIVE: To determine the associations between the polymorphisms of N372H in BRCA2 gene and 135G/C in RAD51 gene and breast cancers. METHODS: The allele and genotype frequencies of N372H in BRCA2 gene and 135G/C in RAD51 gene were analyzed with denaturing high performance liquid chromatography (DHPLC) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 71 women with breast cancers and 85 normal, women. RESULTS: The women with breast cancers had higher frequencies of genotype HH of the N372H locus in BRCA2 gene than the normal women. No statistical difference in the polymorphic distribution of 135G/C in RAD51 gene was observed between the two groups of women. CONCLUSION: The genotype HH of the N372H locus in BRCA2 is associated with breast cancers, which might be a genetic risk factor for breast cancers in Chinese populations.

[A related analysis for alpha, beta fibrinogen gene haplotypes and nucleotide polymorphisms associated with the ischemic stroke in Hainan Han population].

OBJECTIVE: To analyze the association of that the polymorphisms and haplotypes of Taq I site in beta fibrinogen gene and the single nucleotide sites -455 G/A, -249 C/T, -148 C/T, +1689T/G, Bsm A I G/C, 448 G/A, Bcl I G/A, Hinf I A/C in beta-fibrinogen gene are linked up with the ischemic stroke(IS). METHODS: Turbidmetric assay was used to measure the plasma fibrinogen level of one hundred and sixty cases with ischemic stroke and one hundred and thirty healthy individuals from Hainanese Han population. The polymorphisms and genotypes were characterized by PCR-RFLP. Hardy-Weinberg equilibrium and statistical differences of allelic, genotype and haplotype frequencies were obtained by Chi-square test. Pairwise linkage disequilibrium was calculated and haplotypes of nine or four polymorphisms were estimated by the EH + program. RESULTS: There were highly significant differences in genotype frequencies and allelic frequencies of the polymorphisms -455 G/A, -148 C/T, 448 G/A, which happened between the IS group and control subjects (P< 0.01). However, the significant differences of the allelic frequencies in the other six polymorphisms were not found between the IS group and the control (P> 0.05). The odds ratio(OR) with the rare alleles of A -455, T -148 and A 448 is 2.46, 2.30 and 2.08 (95% confidence interval 1.153%-3.924%, 1.429%-3.694% and 1.298%-3.329%) respectively. No definite haplotype block was found by linkage disequilibrium analysis in the control group and the IS group. Association of haplotypes constructed from the nine polymorphisms with IS was not found. Among the haplotypes constructed from four polymorphisms including -455 G/A, -148 C/T, 448 G/A alleles, haplotype differences were found between the control group and the IS group. Haplotypes with G -455, C -148, G448 alleles appeared more frequently in control group(P< or = 0.01), whereas haplotypes with A -455, T -148, A 448 occurred more frequently in the IS group(P< 0.01). CONCLUSION: The results of multi-allele and haplotype analysis indicated that the polymorphisms -455 G/A, -148 C/T, 448 G/A in beta fibrinogen gene were the possible risk factors associated with the occurrence of ischemic stroke in Hainan Han population.

[Nine polymorphisms of fibrinogen gene and their association with plasma fibrinogen levels in Hainan Han population].

OBJECTIVE: To investigate the allelic frequencies of polymorphisms of alpha Taq I and beta Bcl I, Hinf I A/C, 448 G/A, beta BsmA I G/C, +1689T/G, -148C/T, -249C/T, -455G/A in Hainan Han population and their association with plasma fibrinogen level. METHODS: Turbidmetric assay was used to measure plasma fibrinogen level of two hundred and thirty-eight healthy individuals. The genotypes were characterized by PCR-RFLP and sequence analysis. The relationships between the genotypes and plasma fibrinogen levels were analyzed by t test and ANOVA. RESULTS: The frequencies of the rare alleles of alpha Taq I and beta Bcl I, Hinf I A/C, 448 G/A, beta BsmA I G/C, +1689T/G, -148C/T, -249C/T, -455G/A polymorphisms were 0.445, 0.239, 0.134, 0.235, 0.273, 0.241, 0.265, 0.441, 0.254 respectively. In the general population, the plasma fibrinogen level is significantly higher in the groups of genotypes -455GA and AA, -148CT and TT, alpha Taq I T1T1 than in the group of wild types(P=0.004, 0.015 and 0.043 respectively). In the men, plasma fibrinogen level is significantly higher in the groups of genotypes -455GA and AA, -148CT and TT, alpha Taq I T1T1, alpha Taq I T1T2 than in the group of wild types(P=0.001, 0.023, 0.003 and 0.032 respectively). In the women, no significant genotype association with plasma fibrinogen level was detected. CONCLUSION: There was linkage disequilibrium between the fibrinogen gene loci. The beta -455G/A beta 448G/A, alpha Fg Taq I polymorphisms were associated with the difference in plasma fibrinogen in men. A(-455), T(-148) and alpha Taq I T1 alleles were associated with higher fibrinogen levels.

[Synthesis and radiopharmacology of S-(2-18F-fluoroethyl)-L-methionine for tumor imaging].

AIM: To develop S-(2-18F-fluoroethyl)-L-methionine (18FEMET) as an amino acid positron emission tomography (PET) tracer for tumors, and to evaluate the value of 18FEMET in the differentiation of experimental tumor and experimental inflammation. METHODS: 18FEMET was prepared by nucleophilic fluorination reaction via a two-step procedure. Biodistribution of 18FEMET in normal mice, carcinoma-bearing mice and inflammatory mice, and 18FEMET PET imaging for carcinoma-bearing mice and inflammatory mice were performed compared with 2-[18F] fluoro-2-deoxy-D-glucose (FDG) and O-(2-[18F] fluoroethyl)-L-tyrosine (FET). RESULTS: The overall radiochemical yield with no decay correction was 15%-25%, the whole synthesis time was about 70 min by manual operation, and the radiochemical purity was above 95%. High uptake and long retention of 18FEMET in pancreas, kidney, colon, liver and heart were observed. But low uptakes in brain and blood were found. Furthermore, high uptake of 18FEMET, FDG and FET in tumor, high uptake of FDG in inflammatory tissue, and almost no uptake of 18FEMET and FET in inflammatory tissue were also observed. CONCLUSION: 18FEMET is easy to prepare and can be used to differentiate between tumor and inflammatory tissue. It seems to be a potential amino acid tracer for tumors with PET imaging.