Serum 25-hydroxyvitamin D and bone mineral density among children and adolescents in a Northwest Chinese city

Although vitamin D is essential for bone health, little is known about prevalence of vitamin D deficiency and low bone mineral density (BMD) among children, especially those in developing countries. It also remains unclear whether serum 25-hydroxyvitamin D [25(OH)D] is associated with BMD among children. We investigated these questions among children and adolescents in Yinchuan (latitude: 38° N), Ningxia, an economically underdeveloped province in Northwest China. A total of 1582 children (756 boys and 826 girls), aged 6–18 years, were recruited from schools using the stratified random sampling method in fall 2015. Serum 25(OH)D concentrations were measured by enzyme-linked immunosorbent assay, and BMD was quantified by dual-energy X-ray absorptiometry. Vitamin D deficiency (defined as serum 25(OH)D ≤ 37.5 nmol/L) was present in 35.5% of study subjects. There were no clear patterns of differences in serum 25(OH)D concentrations across the four age groups compared (6–9 years, 10–13 years, 14–16 years, and 17–18 years). The prevalence of low total body less head (TBLH) BMD (defined as a Z-score of ≤ −2.0 standard deviations away from the mean BMD values of the Chinese pediatric reference population) among children examined was 1.8% and was not significantly different among the four age groups considered. Linear regression analysis revealed that age, weight, and height were significantly and positively associated with TBLH BMD and that the strongest determinant of TBLH BMD was age in boys and weight in girls. There were no significant correlations between serum 25(OH)D concentrations and BMD obtained for total body and at various skeletal sites (r ranged from −0.005 to 0.014) regardless of whether children evaluated were sufficient, insufficient, or deficient in vitamin D. In conclusion, more than one-third of children and adolescents in a Northwest Chinese city were deficient in vitamin D but only <2% of them developed low BMD

Corrigendum to: The TianQin project: current progress on science and technology

In the originally published version, this manuscript included an error related to indicating the corresponding author within the author list. This has now been corrected online to reflect the fact that author Jun Luo is the corresponding author of the article

Measurement of the Cross Section for Electromagnetic Dissociation with Neutron Emission in Pb-Pb Collisions at √sNN = 2.76 TeV

The first measurement of neutron emission in electromagnetic dissociation of 208Pb nuclei at the LHC is presented. The measurement is performed using the neutron Zero Degree Calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √sNN = 2.76 TeV with neutron emission are σ_single EMD = 187.2±0.2 (stat.) +13.8−12.0 (syst.) b and σ_mutual EMD = 6.2 ± 0.1 (stat.) ±0.4 (syst.) b respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.publishedVersio

L0/L1 trigger generation by the ALICE PHOS detector

Quark-Gluon Plasma (QGP) is a phase that exists above a critical temperature and corresponding energy density according to the theory of Quantum Chromo-Dynamics (QCD). The studies of the QGP help us to understand the early evolution of our universe and the Standard Model. A large Ion Collider Experiment (ALICE) aims to study the properties of the QGP. A QGP can not be observed directly because it is a short lived state. Signatures such as jet quenching, flow pattern and high pT suppression indicate the existence of a QGP. Various sub-detectors are designed for detecting these signatures. The PHOton Spectrometer (PHOS), one of the sub-detectors, is a high-resolution electromagnetic calorimeter dedicated to the precise measurement of direct photon and neutral meson yields in a pT range up to 100 GeV/c. Four online systems are developed to monitor, control and read out the different subdetectors. The trigger system is one of them. The task of the trigger system is to select events of interest and to reduce the overall data flow in the ALICE experiment. Three levels of triggers and a High Level Trigger (HLT) are designed to make optimal use of different sub-detectors, which vary in readout time. The PHOS detector generates two levels of triggers: i) the Level-0 (L0) trigger selects high pT clusters in Pb+Pb and in p+p collisions; ii) the Level-1 (L1) trigger corresponds to a more sophisticated shower analysis which refines the event selection. The main objective of the thesis has been to develop the PHOS trigger firmware, to implement it in an FPGA and to commission it. The ALICE L0 trigger has a latency of 1.2 μs, limiting the time for generating L0 triggers in the PHOS detector. The algorithms are based on the digitized signal from Avalanche Photo-Diodes (APDs). A sliding-window cluster reconstructor is the critical part. A lot of efforts have been made to fulfill the timing requirement. The ALICE L1 trigger has a latency of 6.5 μs, leaving more time to refine the event selection. There are three types of L1 triggers for PHOS: one basic L1 trigger and two advanced ones: total energy trigger and isolated photon trigger. The firmware development focuses on the L0 generation (chapter 5). The timing analysis (chapter 5), testing and commissioning of the PHOS L0 trigger, which is the main effort during the PhD project as well, have been performed (chapter 7). The generation of L1 triggers is discussed in chapter 6, where the firmware for the basic L1 trigger is implemented. The algorithms and related resource consumption for the advanced L1 triggers are analyzed, but they have not been commissioned yet. Additionally, simulations have been done to analyze how several factors affect the trigger performance (chapter 6). The outline of this thesis is given as follows: After a very brief overview of the physics goal, the sub-detectors and the online systems of the ALICE experiment are described in chapter 1. The PHOS detector is specified thoroughly in chapter 2. Chapter 3 introduces the trigger and readout electronics, based on which the firmware for the triggers (chapter 5) is implemented for the PHOS detector. In chapter 4, the requirements of the ALICE PHOS triggers are given in detail. The principle of issuing triggers is discussed elaborately based on the layout of the detector, irrespective of the trigger electronics. Chapters 5 and 6 discuss the generation of L0 and L1 triggers respectively. Chapter 7 gives the commissioning results. Finally, the conclusion and an outlook are given in chapter 8. The trigger firmware is implemented by two types of electronics boards, Trigger Region Unit (TRU) and Trigger-OR (TOR), I’m responsible for the TOR since 2008. The L0 trigger commissioning has started in Oct. 2008, and it is still ongoing. In addition, I performed the timing analysis, the energy and trigger channel correlation analysis and the L0 trigger performance analysis. Because the L1 algorithm was implemented in the TOR, I analyzed algorithms, resource and timing consumption of all three types L1 triggers, and simulated the L1 trigger performance

L0/L1 trigger generation by the ALICE PHOS detector

Quark-Gluon Plasma (QGP) is a phase that exists above a critical temperature and corresponding energy density according to the theory of Quantum Chromo-Dynamics (QCD). The studies of the QGP help us to understand the early evolution of our universe and the Standard Model. A large Ion Collider Experiment (ALICE) aims to study the properties of the QGP. A QGP can not be observed directly because it is a short lived state. Signatures such as jet quenching, flow pattern and high pT suppression indicate the existence of a QGP. Various sub-detectors are designed for detecting these signatures. The PHOton Spectrometer (PHOS), one of the sub-detectors, is a high-resolution electromagnetic calorimeter dedicated to the precise measurement of direct photon and neutral meson yields in a pT range up to 100 GeV/c. Four online systems are developed to monitor, control and read out the different subdetectors. The trigger system is one of them. The task of the trigger system is to select events of interest and to reduce the overall data flow in the ALICE experiment. Three levels of triggers and a High Level Trigger (HLT) are designed to make optimal use of different sub-detectors, which vary in readout time. The PHOS detector generates two levels of triggers: i) the Level-0 (L0) trigger selects high pT clusters in Pb+Pb and in p+p collisions; ii) the Level-1 (L1) trigger corresponds to a more sophisticated shower analysis which refines the event selection. The main objective of the thesis has been to develop the PHOS trigger firmware, to implement it in an FPGA and to commission it. The ALICE L0 trigger has a latency of 1.2 μs, limiting the time for generating L0 triggers in the PHOS detector. The algorithms are based on the digitized signal from Avalanche Photo-Diodes (APDs). A sliding-window cluster reconstructor is the critical part. A lot of efforts have been made to fulfill the timing requirement. The ALICE L1 trigger has a latency of 6.5 μs, leaving more time to refine the event selection. There are three types of L1 triggers for PHOS: one basic L1 trigger and two advanced ones: total energy trigger and isolated photon trigger. The firmware development focuses on the L0 generation (chapter 5). The timing analysis (chapter 5), testing and commissioning of the PHOS L0 trigger, which is the main effort during the PhD project as well, have been performed (chapter 7). The generation of L1 triggers is discussed in chapter 6, where the firmware for the basic L1 trigger is implemented. The algorithms and related resource consumption for the advanced L1 triggers are analyzed, but they have not been commissioned yet. Additionally, simulations have been done to analyze how several factors affect the trigger performance (chapter 6). The outline of this thesis is given as follows: After a very brief overview of the physics goal, the sub-detectors and the online systems of the ALICE experiment are described in chapter 1. The PHOS detector is specified thoroughly in chapter 2. Chapter 3 introduces the trigger and readout electronics, based on which the firmware for the triggers (chapter 5) is implemented for the PHOS detector. In chapter 4, the requirements of the ALICE PHOS triggers are given in detail. The principle of issuing triggers is discussed elaborately based on the layout of the detector, irrespective of the trigger electronics. Chapters 5 and 6 discuss the generation of L0 and L1 triggers respectively. Chapter 7 gives the commissioning results. Finally, the conclusion and an outlook are given in chapter 8. The trigger firmware is implemented by two types of electronics boards, Trigger Region Unit (TRU) and Trigger-OR (TOR), I’m responsible for the TOR since 2008. The L0 trigger commissioning has started in Oct. 2008, and it is still ongoing. In addition, I performed the timing analysis, the energy and trigger channel correlation analysis and the L0 trigger performance analysis. Because the L1 algorithm was implemented in the TOR, I analyzed algorithms, resource and timing consumption of all three types L1 triggers, and simulated the L1 trigger performance

Design of auto-calibration system for multi-channel strain gauge

In view of problem of wasting time and energy and low efficiency in calibrating process of existing calibration method of strain gauges which adopts single-channel manual operation mode, an auto-calibration system based on cortex-M3 MCU was designed，hardware and software design of the system were introduced in details. The system can output standard resistance signal to input terminal of calibration bridge , and can automatically compute precision of calibrate bridge through comparison value between actual outputs and theoretical outputs. The experimental results show that the system can perform auto-calibration of strain gauge efficiently with calibration precision at 0.5%

Characteristics of Soil Nutrients and Their Ecological Stoichiometry in Different Land Use Types in the Nianchu River Basin

Land use types can cause changes in soil chemical characteristics, such as altering soil C, N, and P contents and distribution. The aim of this study was to investigate the status of soil C, N, P and other nutrient contents and their stoichiometric ratios in the terrestrial ecosystem of Nianchu River Basin, Tibet. A total of 102 sample plots with 306 soil samples and 102 plant samples were investigated in August 2021 along the Nianchu River basin by selecting four land-use types: grassland, shrubland, forestland, and farmland. The soil&rsquo;s basic physical and chemical properties (soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), alkaline nitrogen (AN), available phosphorus (AP), pH, and soil particle composition) were examined at each sampling point, and the stoichiometric characteristics of C, N, and P of the soils were analyzed using one-way analysis of variance (ANOVAs). The results revealed that the C and N contents of shrubland were significantly lower than those of grassland, forestland, and farmland, with farmland having the highest P content. For all land types, C:N increased with increasing soil depth, while C:P and N:P decreased with increasing soil depth. PCA and RDA analyses revealed that soil texture and pH had an impact on soil C, N, and P contents, as well as stoichiometric ratios