83 results
Acceleration of 60 MeV proton beams in the commissioning experiment of the SULF-10 PW laser
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- A. X. Li, C. Y. Qin, H. Zhang, S. Li, L. L. Fan, Q. S. Wang, T. J. Xu, N. W. Wang, L. H. Yu, Y. Xu, Y. Q. Liu, C. Wang, X. L. Wang, Z. X. Zhang, X. Y. Liu, P. L. Bai, Z. B. Gan, X. B. Zhang, X. B. Wang, C. Fan, Y. J. Sun, Y. H. Tang, B. Yao, X. Y. Liang, Y. X. Leng, B. F. Shen, L. L. Ji, R. X. Li, Z. Z. Xu
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- Journal:
- High Power Laser Science and Engineering / Volume 10 / 2022
- Published online by Cambridge University Press:
- 03 August 2022, e26
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We report the experimental results of the commissioning phase in the 10 PW laser beamline of the Shanghai Superintense Ultrafast Laser Facility (SULF). The peak power reaches 2.4 PW on target without the last amplifying during the experiment. The laser energy of 72 ± 9 J is directed to a focal spot of approximately 6 μm diameter (full width at half maximum) in 30 fs pulse duration, yielding a focused peak intensity around 2.0 × 1021 W/cm2. The first laser-proton acceleration experiment is performed using plain copper and plastic targets. High-energy proton beams with maximum cut-off energy up to 62.5 MeV are achieved using copper foils at the optimum target thickness of 4 μm via target normal sheath acceleration. For plastic targets of tens of nanometers thick, the proton cut-off energy is approximately 20 MeV, showing ring-like or filamented density distributions. These experimental results reflect the capabilities of the SULF-10 PW beamline, for example, both ultrahigh intensity and relatively good beam contrast. Further optimization for these key parameters is underway, where peak laser intensities of 1022–1023 W/cm2 are anticipated to support various experiments on extreme field physics.
Evaluation of the frequency of mutation genes in multidrug-resistant tuberculosis (MDR-TB) strains in Beijing, China
- Y. Liu, Y. Sun, X. Zhang, Z. Zhang, Q. Xing, W. Ren, C. Yao, J. Yu, B. Ding, S. Wang, C. Li
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- Journal:
- Epidemiology & Infection / Volume 149 / 2021
- Published online by Cambridge University Press:
- 05 January 2021, e21
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The aim of this study was to explore the frequency and distribution of gene mutations that are related to isoniazid (INH) and rifampin (RIF)-resistance in the strains of the multidrug-resistant tuberculosis (MDR-TB) Mycobacterium tuberculosis (M.tb) in Beijing, China. In this retrospective study, the genotypes of 173 MDR-TB strains were analysed by spoligotyping. The katG, inhA genes and the promoter region of inhA, in which genetic mutations confer INH resistance; and the rpoB gene, in which genetic mutations confer RIF resistance, were sequenced. The percentage of resistance-associated nucleotide alterations among the strains of different genotypes was also analysed. In total, 90.8% (157/173) of the MDR strains belonged to the Beijing genotype. Population characteristics were not significantly different among the strains of different genotypes. In total, 50.3% (87/173) strains had mutations at codon S315T of katG; 16.8% (29/173) of strains had mutations in the inhA promoter region; of them, 5.5% (15/173) had point mutations at −15 base (C→T) of the inhA promoter region. In total, 86.7% (150/173) strains had mutations at rpoB gene; of them, 40% (69/173) strains had mutations at codon S531L of rpoB. The frequency of mutations was not significantly higher in Beijing genotypic MDR strains than in non-Beijing genotypes. Beijing genotypic MDR-TB strains were spreading in Beijing and present a major challenge to TB control in this region. A high prevalence of katG Ser315Thr, inhA promoter region (−15C→T) and rpoB (S531L) mutations was observed. Molecular diagnostics based on gene mutations was a useful method for rapid detection of MDR-TB in Beijing, China.
Neutron Star Extreme Matter Observatory: A kilohertz-band gravitational-wave detector in the global network
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- K. Ackley, V. B. Adya, P. Agrawal, P. Altin, G. Ashton, M. Bailes, E. Baltinas, A. Barbuio, D. Beniwal, C. Blair, D. Blair, G. N. Bolingbroke, V. Bossilkov, S. Shachar Boublil, D. D. Brown, B. J. Burridge, J. Calderon Bustillo, J. Cameron, H. Tuong Cao, J. B. Carlin, S. Chang, P. Charlton, C. Chatterjee, D. Chattopadhyay, X. Chen, J. Chi, J. Chow, Q. Chu, A. Ciobanu, T. Clarke, P. Clearwater, J. Cooke, D. Coward, H. Crisp, R. J. Dattatri, A. T. Deller, D. A. Dobie, L. Dunn, P. J. Easter, J. Eichholz, R. Evans, C. Flynn, G. Foran, P. Forsyth, Y. Gai, S. Galaudage, D. K. Galloway, B. Gendre, B. Goncharov, S. Goode, D. Gozzard, B. Grace, A. W. Graham, A. Heger, F. Hernandez Vivanco, R. Hirai, N. A. Holland, Z. J. Holmes, E. Howard, E. Howell, G. Howitt, M. T. Hübner, J. Hurley, C. Ingram, V. Jaberian Hamedan, K. Jenner, L. Ju, D. P. Kapasi, T. Kaur, N. Kijbunchoo, M. Kovalam, R. Kumar Choudhary, P. D. Lasky, M. Y. M. Lau, J. Leung, J. Liu, K. Loh, A. Mailvagan, I. Mandel, J. J. McCann, D. E. McClelland, K. McKenzie, D. McManus, T. McRae, A. Melatos, P. Meyers, H. Middleton, M. T. Miles, M. Millhouse, Y. Lun Mong, B. Mueller, J. Munch, J. Musiov, S. Muusse, R. S. Nathan, Y. Naveh, C. Neijssel, B. Neil, S. W. S. Ng, V. Oloworaran, D. J. Ottaway, M. Page, J. Pan, M. Pathak, E. Payne, J. Powell, J. Pritchard, E. Puckridge, A. Raidani, V. Rallabhandi, D. Reardon, J. A. Riley, L. Roberts, I. M. Romero-Shaw, T. J. Roocke, G. Rowell, N. Sahu, N. Sarin, L. Sarre, H. Sattari, M. Schiworski, S. M. Scott, R. Sengar, D. Shaddock, R. Shannon, J. SHI, P. Sibley, B. J. J. Slagmolen, T. Slaven-Blair, R. J. E. Smith, J. Spollard, L. Steed, L. Strang, H. Sun, A. Sunderland, S. Suvorova, C. Talbot, E. Thrane, D. Töyrä, P. Trahanas, A. Vajpeyi, J. V. van Heijningen, A. F. Vargas, P. J. Veitch, A. Vigna-Gomez, A. Wade, K. Walker, Z. Wang, R. L. Ward, K. Ward, S. Webb, L. Wen, K. Wette, R. Wilcox, J. Winterflood, C. Wolf, B. Wu, M. Jet Yap, Z. You, H. Yu, J. Zhang, J. Zhang, C. Zhao, X. Zhu
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 37 / 2020
- Published online by Cambridge University Press:
- 05 November 2020, e047
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Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
Selective amplification of the chirped attosecond pulses produced from relativistic electron mirrors
- F. Tan, S. Y. Wang, B. Zhang, Z. M. Zhang, B. Zhu, Y. C. Wu, M. H. Yu, Y. Yang, G. Li, T. K. Zhang, Y. H. Yan, F. Lu, W. Fan, W. M. Zhou, Y. Q. Gu
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- Journal:
- Laser and Particle Beams / Volume 38 / Issue 2 / June 2020
- Published online by Cambridge University Press:
- 03 July 2020, pp. 165-168
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In this paper, the generation of relativistic electron mirrors (REM) and the reflection of an ultra-short laser off the mirrors are discussed, applying two-dimension particle-in-cell simulations. REMs with ultra-high acceleration and expanding velocity can be produced from a solid nanofoil illuminated normally by an ultra-intense femtosecond laser pulse with a sharp rising edge. Chirped attosecond pulse can be produced through the reflection of a counter-propagating probe laser off the accelerating REM. In the electron moving frame, the plasma frequency of the REM keeps decreasing due to its rapid expansion. The laser frequency, on the contrary, keeps increasing due to the acceleration of REM and the relativistic Doppler shift from the lab frame to the electron moving frame. Within an ultra-short time interval, the two frequencies will be equal in the electron moving frame, which leads to the resonance between laser and REM. The reflected radiation near this interval and corresponding spectra will be amplified due to the resonance. Through adjusting the arriving time of the probe laser, a certain part of the reflected field could be selectively amplified or depressed, leading to the selective adjustment of the corresponding spectra.
The CLDN5 locus may be involved in the vulnerability to schizophrenia
- Z.-Y. Sun, J. Wei, L. Xie, Y. Shen, S.-Z. Liu, G.-Z. Ju, J.-P. Shi, Y.-Q. Yu, X. Zhang, Q. Xu, G.P. Hemmings
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- European Psychiatry / Volume 19 / Issue 6 / September 2004
- Published online by Cambridge University Press:
- 16 April 2020, pp. 354-357
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The present study was designed to detect three single nucleotide polymorphisms (SNPs) located on 22q11 that was thought as being of particularly importance for genetic research into schizophrenia. We recruited a total of 176 Chinese family trios of Han descent, consisting of mothers, fathers and affected offspring with schizophrenia for the genetic analysis. The transmission disequilibrium test (TDT) showed that of three SNPs, rs10314 in the 3′-untranslated region of the CLDN5 locus was associated with schizophrenia (χ2 = 4.75, P = 0.029). The other two SNPs, rs1548359 present in the CDC45L locus centromeric of rs10314 and rs739371 in the 5′-flanking region of the CLDN5 locus, did not show such an association. The global chi-square (χ2) test showed that the 3-SNP haplotype system was not associated with schizophrenia although the 1-df test for individual haplotypes showed that the rs1548359(C)-rs10314(G)-rs739371(C) haplotype was excessively non-transmitted (χ2 = 5.32, P = 0.02). Because the claudin proteins are a major component for barrier-forming tight junctions that could play a crucial role in response to changing natural, physiological and pathological conditions, the CLDN5 association with schizophrenia may be an important clue leading to look into a meeting point of genetic and environmental factors.
P-1330 - Population-based and Family-based Association Studies of Ank3 Locus and Schizophrenia
- A. Yuan, Q. Wang, Z. Yi, J. Sun, Z. Li, Y. Du, H. Li, Y. Liu, J. Fan, S. Yu
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- European Psychiatry / Volume 27 / Issue S1 / 2012
- Published online by Cambridge University Press:
- 15 April 2020, p. 1
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Objective
rs10761482 in ANK3 gene showed a significant association with schizophrenia in a genome-wide association study (GWAS). Another marker rs10994336 in ANK3 with the risk of bipolar disorder (BD) which might have more genetic overlap with schizophrenia, had been reported in two meta-analyses of GWAS. In this study, we investigated the association between ANK3 polymorphisms and the susceptibility of schizophrenia in Chinese Han population.
MethodsPopulation-based (schizophrenia patients = 516 and controls = 400) and family based (trios of early onset schizophrenia= 81) study was performed through genotyping the most promising makers rs10761482, rs10994336, and two missenses rs3808942 and rs3808943 near promoter of ANK3. Particularly, we conducted an association analysis for the combined case-control and family samples.
ResultsOur population-based study replicated the association between rs10761482 (P = 0.0268 with C allele) and schizophrenia, and detected a novel association with rs10994336 (P = 4.0 × 10−4 with T allele). Haplotype analysis revealed the higher frequencies of C-T, and T-C (rs10761482–10994336) in the cases than controls (P = 0.0032 and P = 0.0012, respectively). In the family study, the C allele of rs10761482 (P = 0.0940) and T allele of rs10994336 (P = 0.0832) were slightly over-transmitted, and T-C was significantly associated with schizophrenia (P = 0.0304). The results from the combined samples analysis were consistent with independent analysis. rs10761482, rs10994336, C-T, and T-C were significantly associated with schizophrenia (P = 3.3 × 10−6∼3.9 × 10−5), whilst rs3808942 and rs3808943 did not reach normal significance.
ConclusionsOur data strongly support ANK3 gene is a schizophrenia susceptibility gene, and also provide further evidence for the shared susceptibility loci between schizophrenia and BD.
The CODATwins Project: The Current Status and Recent Findings of COllaborative Project of Development of Anthropometrical Measures in Twins
- K. Silventoinen, A. Jelenkovic, Y. Yokoyama, R. Sund, M. Sugawara, M. Tanaka, S. Matsumoto, L. H. Bogl, D. L. Freitas, J. A. Maia, J. v. B. Hjelmborg, S. Aaltonen, M. Piirtola, A. Latvala, L. Calais-Ferreira, V. C. Oliveira, P. H. Ferreira, F. Ji, F. Ning, Z. Pang, J. R. Ordoñana, J. F. Sánchez-Romera, L. Colodro-Conde, S. A. Burt, K. L. Klump, N. G. Martin, S. E. Medland, G. W. Montgomery, C. Kandler, T. A. McAdams, T. C. Eley, A. M. Gregory, K. J. Saudino, L. Dubois, M. Boivin, M. Brendgen, G. Dionne, F. Vitaro, A. D. Tarnoki, D. L. Tarnoki, C. M. A. Haworth, R. Plomin, S. Y. Öncel, F. Aliev, E. Medda, L. Nisticò, V. Toccaceli, J. M. Craig, R. Saffery, S. H. Siribaddana, M. Hotopf, A. Sumathipala, F. Rijsdijk, H.-U. Jeong, T. Spector, M. Mangino, G. Lachance, M. Gatz, D. A. Butler, W. Gao, C. Yu, L. Li, G. Bayasgalan, D. Narandalai, K. P. Harden, E. M. Tucker-Drob, K. Christensen, A. Skytthe, K. O. Kyvik, C. A. Derom, R. F. Vlietinck, R. J. F. Loos, W. Cozen, A. E. Hwang, T. M. Mack, M. He, X. Ding, J. L. Silberg, H. H. Maes, T. L. Cutler, J. L. Hopper, P. K. E. Magnusson, N. L. Pedersen, A. K. Dahl Aslan, L. A. Baker, C. Tuvblad, M. Bjerregaard-Andersen, H. Beck-Nielsen, M. Sodemann, V. Ullemar, C. Almqvist, Q. Tan, D. Zhang, G. E. Swan, R. Krasnow, K. L. Jang, A. Knafo-Noam, D. Mankuta, L. Abramson, P. Lichtenstein, R. F. Krueger, M. McGue, S. Pahlen, P. Tynelius, F. Rasmussen, G. E. Duncan, D. Buchwald, R. P. Corley, B. M. Huibregtse, T. L. Nelson, K. E. Whitfield, C. E. Franz, W. S. Kremen, M. J. Lyons, S. Ooki, I. Brandt, T. S. Nilsen, J. R. Harris, J. Sung, H. A. Park, J. Lee, S. J. Lee, G. Willemsen, M. Bartels, C. E. M. van Beijsterveldt, C. H. Llewellyn, A. Fisher, E. Rebato, A. Busjahn, R. Tomizawa, F. Inui, M. Watanabe, C. Honda, N. Sakai, Y.-M. Hur, T. I. A. Sørensen, D. I. Boomsma, J. Kaprio
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- Journal:
- Twin Research and Human Genetics / Volume 22 / Issue 6 / December 2019
- Published online by Cambridge University Press:
- 31 July 2019, pp. 800-808
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The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
Sodium and chloride requirements of yellow-feathered chickens between 22 and 42 days of age
- S. Q. Jiang, M. M. Azzam, H. Yu, Q. L. Fan, L. Li, Z. Y. Gou, X. J. Lin, M. Liu, Z. Y. Jiang
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Sodium and chloride are the key factors maintaining normal osmotic pressure (OSM) and volume of the extracellular fluid, and influencing the acid–base balance of body fluids. The experiment was conducted to investigate the effects of dietary Na+ and Cl− level on growth performance, excreta moisture, blood biochemical parameters, intestinal Na+–glucose transporter 1 (SGLT1) messenger RNA (mRNA), and Na+–H+ exchanger 2 (NHE2) mRNA, and to estimate the optimal dietary sodium and chlorine level for yellow-feathered chickens from 22 to 42days. A total of 900 22-day-old Lingnan yellow-feathered male chickens were randomly allotted to five treatments, each of which included six replicates of 30 chickens per floor pen. The basal control diet was based on corn and soybean meal (without added NaCl and NaHCO3). Treatments 2 to 5 consisted of the basal diet supplemented with equal weights of Na+ and Cl−, constituting 0.1%, 0.2%, 0.3% and 0.4% of the diets. Supplemental dietary Na+ and Cl− improved the growth performance (P<0.05). Average daily gain (ADG) showed a quadratic broken-line regression to increasing dietary Na+ and Cl− (R2=0.979, P<0.001), and reached a plateau at 0.1%. Supplemental Na+ and Cl− increased (P<0.05) serum Na+ and OSM in serum and showed a quadratic broken-line regression (R2=0.997, P=0.004) at 0.11%. However, supplemental Na+ and Cl− decreased (P<0.05) serum levels of K+, glucose (GLU) and triglyceride. Higher levels of Na+and Cl− decreased duodenal NHE2 transcripts (P<0.05), but had no effect on ileal SGLT1 transcripts. The activity of Na+ /K+-ATPase in the duodenum decreased (P<0.05) with higher levels of dietary Na+ and Cl−. In conclusion, the optimal dietary Na+ and Cl− requirements for yellow-feathered chickens in the grower phase, from 22 to 42 days of age, to optimize ADG, serum Na+, OSM, K+ and GLU were 0.10%, 0.11%, 0.11%,0.17% and 0.16%, respectively, by regression analysis.
Screening of reference genes using real-time quantitative PCR for gene expression studies in Neoseiulus barkeri Hughes (Acari: Phytoseiidae)
- C. Wang, J. Yang, Q. Pan, S. Yu, R. Luo, H. Liu, H. Li, L. Cong, C. Ran
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- Bulletin of Entomological Research / Volume 109 / Issue 4 / August 2019
- Published online by Cambridge University Press:
- 29 October 2018, pp. 443-452
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A stable reference gene is a key prerequisite for accurate assessment of gene expression. At present, the real-time reverse transcriptase quantitative polymerase chain reaction has been widely used in the analysis of gene expression in a variety of organisms. Neoseiulus barkeri Hughes (Acari: Phytoseiidae) is a major predator of mites on many important economically crops. Until now, however, there are no reports evaluating the stability of reference genes in this species. In view of this, we used GeNorm, NormFinder, BestKeeper, and RefFinder software tools to evaluate the expression stability of 11 candidate reference genes in developmental stages and under various abiotic stresses. According to our results, β-ACT and Hsp40 were the top two stable reference genes in developmental stages. The Hsp60 and Hsp90 were the most stable reference genes in various acaricides stress. For alterations in temperature, Hsp40 and α-TUB were the most suitable reference genes. About UV stress, EF1α and α-TUB were the best choice, and for the different prey stress, β-ACT and α-TUB were best suited. In normal conditions, the β-ACT and α-TUB were the two of the highest stable reference genes to respond to all kinds of stresses. The current study provided a valuable foundation for the further analysis of gene expression in N. barkeri.
A cross-sectional study of acute diarrhea in Pudong, Shanghai, China: prevalence, risk factors, and healthcare-seeking practices
- J.-X. YU, W.-P. ZHU, C.-C. YE, C.-Y. XUE, S.-J. LAI, H.-L. ZHANG, Z.-K. ZHANG, Q.-B. GENG, W.-Z. YANG, Q. SUN, Z.-J. LI
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- Journal:
- Epidemiology & Infection / Volume 145 / Issue 13 / October 2017
- Published online by Cambridge University Press:
- 23 August 2017, pp. 2735-2744
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Diarrhea is a common cause of morbidity and mortality and the incidence of diarrhea in the world has changed little over the past four decades. To assess the prevalence of and healthcare practices for diarrhea, a cross-sectional study was conducted in Pudong, Shanghai, China. In October 2014, a total of 5324 community residents were interviewed. Respondents were asked if they had experienced diarrhea (defined as ⩾3 passages of watery, loose, bloody, or mucoid stools within a 24-h period) in the previous month prior to the interview. The monthly prevalence of diarrhea was 4·1% (95% CI: 3·3–4·8), corresponding to an incidence rate of 0·54 episodes per person-year. The proportion of individuals with diarrhea who sought healthcare was 21·2% (95% CI: 13·4–29·0). Diarrhea continues to impose a considerable burden on the community and healthcare system in Pudong. Young age and travel were identified as predictors of increased diarrhea occurrence.
Gene cloning and difference analysis of vitellogenin in Neoseiulus barkeri (Hughes)
- L. Ding, F. Chen, R. Luo, Q. Pan, C. Wang, S. Yu, L. Cong, H. Liu, H. Li, C. Ran
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- Bulletin of Entomological Research / Volume 108 / Issue 2 / April 2018
- Published online by Cambridge University Press:
- 11 July 2017, pp. 141-149
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Neoseiulus barkeri (HUGHES) is the natural enemy of spider mites, whiteflies and thrips. Screening for chemically-resistant predatory mites is a practical way to balance the contradiction between the pesticide using and biological control. In this study, the number of eggs laid by fenpropathrin-susceptible and resistant strains of N. barkeri was compared. Additionally, we cloned three N. barkeri vitellogenin (Vg) genes and used quantitative real-time polymerase chain reaction to quantify Vg expression in susceptible and resistant strains. The total number of eggs significantly increased in the fenpropathrin-resistant strain. The full-length cDNA cloning of three N. barkeri Vg genes (NbVg1, NbVg2 and NbVg3) revealed that the open reading frames of NbVg1, NbVg2 and NbVg3 were 5571, 5532 and 4728 bp, encoding 1856, 1843 and 1575 amino acids, respectively. The three N. barkeri Vg possessed the Vitellogenin-N domain (or lipoprotein N-terminal domain (LPD_N)), von Willebrand factor type D domain (VWD) and the domain with unknown function 1943 (DUF1943). The NbVg1 and NbVg2 expression levels were significantly higher in the resistant strain than in the susceptible strain, while the NbVg3 expression level was lower in the resistant strain. Thus, we speculate that the increased number of eggs laid by the fenpropathrin-resistant strain of N. barkeri may be a consequence of changes in Vg gene expression.
9 - Adaptive Compression in C-RANs
- from Part II - Physical-Layer Design in C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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- Cloud Radio Access Networks
- Published online:
- 23 February 2017
- Print publication:
- 02 February 2017, pp 200-224
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Summary
Cloud radio access networks (C-RANs) provide a promising architecture for the future mobile networks needed to sustain the exponential growth of the data rate. In C-RAN, one data processing center or baseband unit communicates with users through distributed remote radio heads, which are connected to the baseband unit (BBU) via high-capacity low-latency so-called fronthaul links. The architecture of C-RAN, however, imposes a burden of fronthaul bandwidth because raw I/Q samples are exchanged between the RRHs and the BBU. Therefore, signal compression is required on fronthaul links owing to their limited capacity. This chapter exploits the advance of joint signal processing to reduce the transmission rate on fronthaul uplinks. In particular, we first propose a joint decompression and detection (JDD) algorithm which exploits the correlation among RRHs and jointly performs decompressing and detecting. The JDD algorithm takes into consideration both fading and quantization effects in a single decoding step. Second, the block error rate of the JDD algorithm is analyzed in a closed form by using pairwise error probability analysis under both deterministic and Rayleigh fading channel models. Third, on the basis of the analyzed block error rate (BLER), we introduce adaptive compression schemes subject to quality of service constraints to minimize the fronthaul transmission rate while satisfying the predefined target QoS. The premise of the proposed compression methods originates from practical scenarios, where most applications tolerate a non-zero BLER. As a dual problem, we also develop a scheme to minimize the signal distortion subject to the fronthaul rate constraint. We finally consider the counterparts of these two adaptive compression schemes for Rayleigh-fading channels and analyze their asymptotic behavior as the constraints approach extremes.
Introduction
Cloud radio access networks have been widely accepted as a new architecture for future mobile networks to sustain the ever increasing demand in the data rate [1]. In a C-RAN, one centralized processor or BBU communicates with users distributed in a graphical area via a number of remote radio heads (RRHs), which act as “soft” relaying nodes and are connected to the BBU via high-capacity and low-latency fronthaul links. By moving all baseband processing functions from RRHs to a centralized processor, the C-RAN enables adaptive load balancing via a virtual base station pool [2] and effective network-wide inter-cell interference management thanks to multi-cell processing [3, 4].
19 - Field Trials and Testbed Design for C-RAN
- from Part IV - Networking in C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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- Cloud Radio Access Networks
- Published online:
- 23 February 2017
- Print publication:
- 02 February 2017, pp 451-471
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Summary
Introduction
Since the proposal of C-RAN [1-3] in 2009, China Mobile (CMCC) has been committed to developing various kinds of proof-of-concept (PoC), test-beds, and field trials to demonstrate C-RAN's benefits and verify the key enabling technologies. This chapter gives a comprehensive introduction to these activities. In particular, we will demonstrate not only the feasibility and reliability of wavelength-division-multiplexing (WDM)-based fronthaul (FH) solutions but also how a noticeable coordinated multiple-points (CoMP) gain can be achieved with the C-RAN architecture. In addition, a virtualized C-RAN system is elaborated, including the design principles, the architecture, and the field trial results.
Field-Trial Verification of FH Solutions
19.2.1 Centralization Field Trials in 2G and 3G Networks
The first step toward C-RAN was baseband unit (BBU) centralization which is relatively easy to implement and can be tested with the existing 2G, 3G, and 4G systems. In the past few years, extensive field trials have been carried out in more than 10 cities in China using commercial 2G, 3G, and pre-commercial TD-LTE networks with different centralization scales. The main objective of C-RAN deployment in 2G and 3G is to demonstrate the deployment benefits of centralization, including accelerated site construction and reduced power consumption. For example, one trial took place in the city of Changchun where 506 2G BSs in five counties were upgraded to a C-RAN-type architecture centralized in several sites. In the largest of these, 21 BSs were aggregated to support 101 RRUs with a total of 312 carriers. It was observed that power consumption was reduced by 41% owing to shared air-conditioning. In addition, system performance in terms of the call-drop rate as well as the downlink data rate was enhanced using multiple RRU-co-cell technologies. For the results and benefits from using centralization in 2G and 3G trials, the reader is referred to [4]. When it comes to TD-LTE, centralization becomes more challenging owing to the high data rate in the FH connection. For example, the data rate of the most widely used FH interface in the industry, the common public radio interface (CPRI), could be as high as 9.8 Gb/s for an TD-LTE carrier with a 20 MHz bandwidth and eight antennas.
Index
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3 - The Tradeoff of Computational Complexity and Achievable Rates in C-RANs
- from Part II - Physical-Layer Design in C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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Summary
Introduction
The trend of increased centralization holds the potential to transform mobile networks in two ways. First, centralization enables the exploitation of common channel knowledge, which in turn allows for significant improvements in the performance of a communication channel by, for instance, performing the joint transmission and reception of signals or allocating resources jointly amongst adjacent cells [1]. Second, centralized processing leverages the trend towards deploying mobile networks on low-cost commodity hardware that is running commodity or open-source software solutions. Deploying software-based implementations increases implementation flexibility, reduces service-creation time, and enables the flexible usage of processing resources through virtualization. In this chapter we use the term Cloud-RAN (C-RAN) to refer to a flexible use of commodity solutions that combines gains in both the telecommunication and information technology domains.
Before implementing the protocol stack of a RAN on a cloud-computing platform, we must also take the required effort into account, e.g., commodity hardware is considered to be less performant and energy efficient than dedicated hardware such as ASIC, DSP, or FPGA. Furthermore, resource virtualization implies an overbooking of resources while satisfying joint resource requirements of all processed base stations (BSs), which is in contrast with fulfilling individual processing constraints at each BS. Centralized signal processing may further impose stringent requirements on the fronthaul network between a radio access point (RAP) and the data center.
So far, research in the area of Cloud-RAN has focused on the telecommunication domain, e.g., the applicability of joint processing approaches, gains from centralization, and optimal degrees of centralization under different side constraints. In this chapter the focus is on the impact of limiting and virtualizing the data processing resources on the communication rate, i.e., the quantitative coupling of the required computational resources and communication rates [2]. After introducing basic notation and definitions, we consider metrics and an analytical framework that allows one to determine the data processing demand Interestingly, the data processing requirements depend not only on the number of information bits but also to a large extent on the quality of a user's communication channel. In this chapter we discuss and quantify multi-user gains, which lower the requirements on the data processing resources to be provided.
1 - Overview of C-RAN
- from Part I - Architecture of C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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Summary
Introduction
In 2008, as the specification for long-term evolution (LTE) Release 8 was frozen in the Third Generation Partner Project (3GPP), operators began to shift the network deployment focus to 4G. In 2009, the world's first commercial LTE network was launched by TeliaSonera in Norway and Sweden. As of today, there are several hundred LTE networks in operation, providing unprecedented user experiences to customers. Consequently, we are witnessing the recent mobile traffic explosion in the telecom industry. It is expected that by 2020 consumer Internet traffic will increase by a factor of over one thousand [1].
As operators roll out and expand 4G networks, more and more challenges arise. First, network deployment is becoming more and more difficult simply due to an insufficient number of equipment rooms. Traditional base stations (BSs) comprise either a co-located baseband unit (BBU) with a radio unit or a distributed BBU with a remote radio unit (RRU) connected via fiber. For either case, a separate equipment room with supporting facilities such as air conditioning is required in order for BS deployment. However, since the operating frequency of LTE is usually higher than that of 2G and 3G, the coverage of an LTE cell is smaller than that of a 2G or 3G cell. As a result, more LTE cells are needed to cover the same area, meaning that more equipment rooms are required. Unfortunately, this is increasingly difficult since available real estate is becoming scarcer and more expensive. Traditional deployment puts a lot of pressure on capital expenditure (CAPEX).
Second, in a society where people are promoting energy conservation and environment protection, power consumption has become a sensitive word and a major concern for operators. It is estimated that the carbon footprint of the ICT industry accounts for 2% of the global total, which is the same as that of the aviation industry. For the telecom industry, further analysis has shown that a large percentage of power consumption in mobile networks comes from radio access networks (RANs) [1, 2]. Take China Mobile's networks, for example. The largest mobile network in the world consumed over 14 billion kWh of energy in 2012 in its network of 1.1 million base stations. It can be seen that saving energy in RANs could directly lower the operating expense (OPEX) of the network.
8 - Fronthaul Compression in C-RANs
- from Part II - Physical-Layer Design in C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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Introduction
The C-RAN architecture relies on fronthaul links to connect each remote radio head (RRH) to the managing baseband unit (BBU). In particular, for the uplink, the fronthaul links allow the RRHs to convey their respective received signals, either in analog format or in the form of digitized baseband samples, to the BBU. For the downlink, the BBU transfers the radio signal that each RRH is to transmit on the radio interface, in analog or digital format, on the fronthaul links to the RRHs. It is this transfer of radio or baseband signals that makes possible the virtualization of the baseband and higherlayer functions of the (RRHs) at the BBU, which defines the C-RAN architecture. The analog transport solution is typically implemented by means of radio-over-fiber (see, e.g., [1]) but solutions based on copper LAN cables are also available [2]. In contrast, the digital transmission of baseband, or IQ, samples is currently carried out by following the common public radio interface (CPRI) specification [3]. This ideally requires fiber optic fronthaul links, although practical constraints motivate the development of wireless-based digital fronthauling [4]. The digital approach seems to have attracted the most interest owing to the traditional advantages of digital solutions, their including resilience to noise and to hardware impairments as well as flexibility in the transport options (see, e.g., [5]). Furthermore, the connection between an RRH and the BBU may be direct, i.e., single-hop, or it may take place over a cascade of fronthaul links, i.e., be multi-hop, as illustrated in Fig. 8.1.
In this chapter we provide an overview of the state of the art on the problem of transporting digitized IQ baseband signals on the fronthaul links. As mentioned, the current de facto standard that defines analog-to-digital processing and transport options is provided by the common public radio interface (CPRI) specification [3]. This specification is widely understood to be unsuitable for the large-scale implementation of C-RAN owing to its significant fronthaul bit rate requirements under common operating conditions. As an example, as reported in [5], the bit rate needed for an LTE base station that serves three cell sectors with carrier aggregation over five carriers and two receive antennas exceeds even the 10 Gbits/s provided by standard fiber optic links.
4 - Cooperative Beamforming and Resource Optimization in C-RANs
- from Part II - Physical-Layer Design in C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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Summary
Cloud radio access network (C-RAN) architecture offers two key advantages as compared with traditional radio access networks (RANs) from the physical-layer transmission point of view. First, the centralization and virtualization of RANs allow the coordination of base stations (BSs) across a large geographic area, thereby enabling coordinated physical-layer resource allocation across the BSs. The physical-layer resources here refer to the frequency, time, and spatial dimensions that can be utilized by radio transmission. Second, and more importantly, the C-RAN architecture also opens up the possibility of the joint transmission and joint reception of user signals across multiple BSs, thereby fundamentally addressing the issue of inter-cell interference. As interference is the main bottleneck in modern densely deployed wireless networks, the C-RAN architecture offers significant advantages in that it provides the possibility of interference mitigation leading to performance enhancement without the need for additional site and bandwidth acquisition.
This chapter provides an optimization framework for cooperative beamforming and resource allocation in C-RANs. We begin by identifying frequency, time, and spatial resources in wireless cellular networks and defining the overall spectrum allocation, scheduling, and beamforming problem in a cooperative network. The chapter then provides a network model for the C-RAN architecture and illustrates typical network objective functions and constraints for network utility maximization. A key characteristic of the C-RAN architecture is that the fronthaul connections between the cloud and the BSs may have limited capacities. One of the main goals of this chapter is to illustrate the impact of limited fronthaul capacity on the cooperative beamforming and resource allocation in C-RANs.
The chapter explores the optimization of the design variables associated with CRANs, depending on the transmission strategies at the cooperative BSs. For the uplink C-RAN, we illustrate compress-forward as the main strategy at the BSs and focus on the impact of the choice of quantization noise levels at the BSs and possible joint transmit optimization strategies. For the downlink C-RAN, we compare a compression-based strategy and a data-sharing strategy and illustrate the problem formulation and solution strategy in both cases. Throughout the chapter, key optimization techniques for solving resource-allocation problems in C-RANs are presented.
Acknowledgments
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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7 - Large-Scale Convex Optimization for C-RANs
- from Part II - Physical-Layer Design in C-RANs
- Edited by Tony Q. S. Quek, Singapore University of Technology and Design, Mugen Peng, Osvaldo Simeone, New Jersey Institute of Technology, Wei Yu, University of Toronto
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Summary
Introduction
7.1.1 C-RANs
The proliferation of “smart” mobile devices, coupled with new types of wireless applications, has led to an exponential growth in wireless and mobile data traffic. In order to provide high-volume and diversified data services, C-RAN [1, 2] has been proposed; it enables efficient interference management and resource allocation by shifting all the baseband units (BBUs) to a single cloud data center, i.e., by forming a BBU pool with powerful shared computing resources. Therefore, with efficient hardware utilization at the BBU pool, a substantial reduction can be obtained in both the CAPEX (e.g., via low-cost site construction) and the OPEX (e.g., via centralized cooling). Furthermore, the powerful conventional base stations are replaced by light and low-cost remote radio heads (RRHs), with the basic functionalities of signal transmission and reception, which are then connected to the BBU pool by high-capacity and low-latency optical fronthaul links. The capacity of C-RANs can thus be significantly improved through network densification and large-scale centralized signal processing at the BBU pool. By further pushing a substantial amount of data, storage, and computing resources (e.g., the radio access units and end-user devices) to the edge of the network, using the principle of mobile edge computing (i.e., fog computing) [3], heterogeneous C-RANs [4], as well as Fog-RANs and MENG-RANs [5] can be formed. These evolved architectures will further improve user experience by offering on-demand and personalized services and location-aware and content-aware applications. In this chapter we investigate the computation aspects of this new network paradigm, and in particular focus on the large-scale convex optimization for signal processing and resource allocation in C-RANs.
7.1.2 Large-Scale Convex Optimization: Challenges and Previous Work
Convex optimization serves as an indispensable tool for resource allocation and signal processing in wireless networks [6-9]. For instance, coordinated beamforming [10] often yields a convex optimization formulation, i.e., second-order cone programming (SOCP) [11]. The network max-min fairness-rate optimization [12] can be solved through the bisection method [11], in polynomial time; in this method a sequence of convex subproblems needs to be solved.