The optimization of a DC injector for the Energy Recovery Linac upgrade to APS

An energy recovery linac based light source is a potential revolutionary upgrade to the Advanced Photon Source (APS) at Argonne National Laboratory. The concept relies on several key research areas, one of which is the generation of ultra-low emittance, high-average-current electron beams. In this paper, we present our investigation of a dc-gun-based system for ultra-low emittance bunches in the 20 pC range. A parallel multi-objective numerical optimization is performed in multi-parameter space. Parameters varied include experimentally feasible drive-laser shapes, the DC gun voltage, the thermal energy of the emitted photo-electrons and other electric or magnetic field strengths, RF cavity phase etc. Our goal is to deliver a {approx}10 MeV, 20 pC bunch at the entrance of the linac with an emittance of 0.1 {micro}m or lower, rms bunch length of 2 {approx} 3 ps, and energy spread no larger than 140 keV. We present the machine parameters needed to generate such an injector beam, albeit without a merger

Wild-Type and Non-Wild-Type Mycobacterium tuberculosis MIC Distributions for the Novel Fluoroquinolone Antofloxacin Compared with Those for Ofloxacin, Levofloxacin, and Moxifloxacin.

Antofloxacin (AFX) is a novel fluoroquinolone that has been approved in China for the treatment of infections caused by a variety of bacterial species. We investigated whether it could be repurposed for the treatment of tuberculosis by studying its in vitro activity. We determined the wild-type and non-wild-type MIC ranges for AFX as well as ofloxacin (OFX), levofloxacin (LFX), and moxifloxacin (MFX), using the microplate alamarBlue assay, of 126 clinical Mycobacterium tuberculosis strains from Beijing, China, of which 48 were OFX resistant on the basis of drug susceptibility testing on Löwenstein-Jensen medium. The MIC distributions were correlated with mutations in the quinolone resistance-determining regions of gyrA (Rv0006) and gyrB (Rv0005). Pharmacokinetic/pharmacodynamic (PK/PD) data for AFX were retrieved from the literature. AFX showed lower MIC levels than OFX but higher MIC levels than LFX and MFX on the basis of the tentative epidemiological cutoff values (ECOFFs) determined in this study. All strains with non-wild-type MICs for AFX harbored known resistance mutations that also resulted in non-wild-type MICs for LFX and MFX. Moreover, our data suggested that the current critical concentration of OFX for Löwenstein-Jensen medium that was recently revised by the World Health Organization might be too high, resulting in the misclassification of phenotypically non-wild-type strains with known resistance mutations as wild type. On the basis of our exploratory PK/PD calculations, the current dose of AFX is unlikely to be optimal for the treatment of tuberculosis, but higher doses could be effective.The work was supported by the research funding from Infectious Diseases Special Project, Minister of Health of China (2016ZX10003001-12) and Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (ZYLX201304). The strains used in this project were obtained from the ‘Beijing Bio-Bank of clinical resources on Tuberculosis’ (D09050704640000), Beijing Chest Hospital. In addition, this study was supported by the Health Innovation Challenge Fund (HICF-T5-342 and WT098600), a parallel funding partnership between the UK Department of Health and Wellcome Trust. T. S. was supported by grants from the Swedish Heart and Lung Foundation and Marianne and Marcus Wallenberg Foundation. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health, Public Health England, or the Wellcome Trust. C. U. K. is a Junior Research Fellow at Wolfson College, Cambridge.This is the author accepted manuscript. The final version is available from American Society for Microbiology at http://dx.doi.org/10.1128/AAC.00393-16

Evaluation of the Ribosomal Protein S1 Gene (rpsA) as a Novel Biomarker for Mycobacterium Species Identification

Objectives. To evaluate the resolution and reliability of the rpsA gene, encoding ribosomal protein S1, as a novel biomarker for mycobacteria species identification. Methods. A segment of the rpsA gene (565 bp) was amplified by PCR from 42 mycobacterial reference strains, 172 nontuberculosis mycobacteria clinical isolates, and 16 M. tuberculosis complex clinical isolates. The PCR products were sequenced and aligned by using the multiple alignment algorithm in the MegAlign package (DNASTAR) and the MEGA program. A phylogenetic tree was constructed by the neighbor-joining method. Results. Comparative sequence analysis of the rpsA gene provided the basis for species differentiation within the genus Mycobacterium. Slow-and rapid-growing groups of mycobacteria were clearly separated, and each mycobacterial species was differentiated as a distinct entity in the phylogenetic tree. The sequences discrepancy was obvious between M. kansasii and M. gastri, M. chelonae and M. abscessus, M. avium and M. intracellulare, and M. szulgai and M. malmoense, which cannot be achieved by 16S ribosomal DNA (rDNA) homologue genes comparison. 183 of the 188 (97.3%) clinical isolates, consisting of 8 mycobacterial species, were identified correctly by rpsA gene blast. Conclusions. Our study indicates that rpsA sequencing can be used effectively for mycobacteria species identification as a supplement to 16S rDNA sequence analysis

PHOTOIONIZATION OF HOCO RADICAL: A NEW UPPER LIMIT TO THE ADIABATIC IONIZATION ENERGY AND LOWER LIMIT TO THE ENTHALPY OF FORMATION

Author Institution: Chemistry Division, Argonne National LaboratoryHOCO radical is important in combustion and atmospheric chemistry. A recent photoionization investigation provides a new value for the adiabatic ionization energy of $EI(t-HOCO) \leq 8.195 \pm 0.022 eV$. Through the positive ion thermochemical cycle, this translates into a lower limit to the enthalpy of formation, $\Delta H^{0}_{f0}(t-HOCO) \geq -45.8 \pm 0.7 kcal/mol (\geq -46.5 \pm 0.7 kcal/mol at 298 K)$, placing t-HOCO only $3.5 \pm 0.7 kcal/mol$ below the $CO_{2}+H$ asymptote. The photoionization spectrum of HOCO corroborates the previous finding of a progression in the double C=O bond stretch of the ion of ${\sim} 2300 cm^{-1}$, suggests the presence of the single C-O bond stretch of $\sim 1200-1300 cm^{-1}$, and provides indirect evidence for the excitation of an even lower frequency, such as the OCO bend. In addition, the data tentatively suggest an ionization onset as low as $8.06 \pm 0.03 eV$. While it is not quite clear whether the latter should correspond to the cis or trans isomer, it may indicate that the enthalpy of formation of HOCO is even higher. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, under Contract No. W-31-109-ENG-38

Great expectations : a qualitative study of how Chinese graduate students navigate academic writing expectations in U.S. higher education.

Thesis (Ph. D.)--University of Rochester. Margaret Warner Graduate School of Education, 2015.Chinese graduate students make great contributions to receiving universities in the United States financially and academically. The increasing number of Chinese graduate students makes it necessary to study their experience of negotiating the unfamiliar expectations of academic writing in the United States. However, little research has explored their academic writing experience. This dissertation aims to explore how Chinese graduate students understand and navigate academic writing expectations in the United States. I draw on two theoretical domains to inform my study--writing as a social practice as my primary theoretical lens and Bourdieu's theory of social, linguistic and cultural capital as the complementary theory. This study begins with two rounds of semistructured qualitative interviews with eight Chinese graduate students across disciplines and then document review of students' writing samples with their instructors' feedback, followed by a focus-group interview with three faculty members who have experience teaching or advising Chinese graduate students. Furthermore, open and focused coding was used to analyze the qualitative data. This study provides insights about the complex writing experiences of Chinese EAL international graduate students around three major themes 1) navigating academic culture shock at graduate-level writing, 2) navigating social relations in writing, and 3) mobilizing resources and strategies available to make sense of and meet writing expectations. This dissertation study provides a rich and nuanced understanding of how Chinese EAL graduate students understand, make sense of and navigate writing expectations. It has suggested the mismatch in writing expectations between Chinese and U.S. academic cultures in many ways, as well as the lack of adequate preparation and international student-friendly support to EAL graduate students. Chinese graduate students had to conceptualize and negotiate academic culture shock and social relationships to transition into graduate level writing in the United States. Future EAL writing research should expand and explore further toward understanding EAL international students' writing as a social construct

Dimension Reduction Localization Algorithm of Mixed Sources Based on MEMS Vector Hydrophone Array

In this paper, a mixed sources dimension reduction Multiple Signal Classification (MUSIC) localization algorithm suitable for Micro-Electro-Mechanical System (MEMS) vector hydrophone linear arrays is proposed, which reduces the two-dimensional search to one-dimensional local search. Firstly, the Lagrangian function is constructed by quadratic optimization idea to obtain the estimates of azimuth angles. Secondly, the least square method is utilized for optimal match to obtain the direction-of-arrivals (DOAs) and ranges, and the range parameters are judged in Fresnel zone to obtain the azimuth information of all near-field sources. Finally, find the common DOAs and achieve high-resolution separation of far-field and near-field sources. Simulation and field experiments prove that the proposed algorithm only needs a small number of elements can solve the problem of port and starboard ambiguity, does not need to construct high-order cumulants or multi-dimensional search while the parameters are automatically matched with low computational complexity. This study provides an idea of the engineering application of vector hydrophone

Soil Microbial Community and Soil Abiotic Factors Are Linked to Microorganisms’ C:N:P Stoichiometry in <i>Larix</i> Plantations

Ecological stoichiometry is an essential tool to understand carbon (C), nitrogen (N), and phosphorus (P) cycles and nutrient limitations. Plantations are usually managed to maintain specific age structures, but the impact of such management on microbial biomass and stoichiometric ratios remains unclear. We compared the stand ages of four Larix principis-rupprechtti Mayr. Plantations that were 15 years old, (young plantation, Lar15), 24 years old, (middle aged plantation, Lar24), 40 years old, (near-mature plantation, Lar40), and 50 years old, (mature plantation, Lar50), respectively, to determine the main factors that drive differences in the C:N:P stoichiometry of microorganisms. We demonstrated that the temperature, moisture, and nutrient concentrations in surface soil increased significantly with forest age. The stoichiometric ratios of elements in soil and microorganisms reached their maxima in the Lar40 and Lar50 plantations. Additionally, forest stand ages had a great influence on the biomass of microbial communities. Moreover, soil microbial community and soil abiotic factors are closely related to soil microorganisms’ C:N:P stoichiometric ratios. Specifically, changes in the microbial biomass C:N (MBC:MBN) were primarily correlated with bacteria, Gram-positive bacteria (G+), temperature, NH4+-N, and moisture in soil. Shifts in G+, actinobacteria, soil temperature, and total phosphorus were primarily associated with variation in microbial biomass C:P (MBC:MBP). Alterations in microbial biomass N:P (MBN:MBP) were correlated with bacteria, NH4+-N, water content, Gram-negative bacteria, and soil temperature. Overall, these results suggest that microbial elemental stoichiometric ratios could be affected by stand age and emphasize the importance of microbial communities and soil abiotic factors in shifting this dynamic change process

Wireless Passive Microwave Antenna-Integrated Temperature Sensor Based on CSRR

A novel, wireless, passive substrate-integrated waveguide (SIW) temperature sensor based on a complementary split-ring resonator (CSRR) is presented for ultra-high-temperature applications. The temperature sensor model was established by using the software of HFSS (ANSYS, Canonsburg, PA, USA) to optimize the performance. This sensor can monitor temperature wirelessly using the microwave backscatter principle, which uses a robust high-temperature co-fired ceramic (HTCC) as the substrate for harsh environments. The results are experimentally verified by measuring the S (1,1) parameter of the interrogator antenna without contact. The resonant frequency of the sensor decreases with the increasing temperature using the dielectric perturbation method, which changes from 2.5808 to 2.35941 GHz as the temperature increases from 25 to 1200 °C. The sensitivity of the sensor is 126.74 kHz/°C in the range of 25–400 °C and 217.33 kHz/°C in the range of 400–1200 °C. The sensor described in this study has the advantages of simple structure, higher quality and sensitivity, and lower environmental interference, and has the potential for utilization in multi-site temperature testing or multi-parameter testing (temperature, pressure, gas) in high-temperature environments