Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-05-09
Abstract: We investigate the implications of the entropic force formalism proposed by Verlinde. We show that an UV/IR relation proposed by Cohen et al., as well as an uncertainty principle proposed by Hogan can be derived from the entropic force formalism. We show that applying the entropic force formalism to cosmology, there is an additional term in the Friedmann equation, which can be identified as holographic dark energy. We also propose an intuitive picture of holographic screen, which can be thought of as an improvement of Susskind's holographic screen.
Peer Review Status:Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-05-09
Abstract: We propose a model in which an energy-dependent time delay of a photon originates from space-time non-commutativity, the time delay is due to a non-commutative coupling between dilaton and photon. We predict that in our model, high energy photons with different momentum can either be delayed or superluminal, this may be related to a possible time delay reported by the Fermi LAT and Fermi GBM Collaborations
Peer Review Status:Awaiting Review
Subjects: Computer Science >> Computer Application Technology submitted time 2023-03-23
Abstract: Object detection based on unmanned aerial vehicle (UAV) images is very challenging. The multi-scale size and high density of objects in the UAV view bring great difficulties. To fully address this issue to unleash the potential of UAV applications, the YOLOv5-STD model is proposed. First, add one more head to locate extremely small object detection by shallow image features; second, use the attention mechanism to optimize the backbone by the transformer; third, use SPD-Conv to avoid the loss of fine-grained image feature information. At the last, sufficient experiments on the dataset VisDrone 2022 have proven that the model has good performance, compared with the basic model, the improved model has an average improvement of about 7% in mAP@.5 metrics, and the ablation experiments have verified that its improvement skills have a positive effect on the model. This paper can help developers and researchers get a better experience in the analysis and processing of unmanned aerial vehicle images.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-12
Abstract: In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-12
Abstract: Solar wind dynamic pressure pulse (DPP) structures, across which the dynamic pressure changes abruptly over timescales from a few seconds to several minutes, are often observed in the near-Earth space environment. The space weather effects of DPPs on the magnetosphere-ionosphere coupling system have been widely investigated in the last two decades. In this study, we perform a statistical survey on the properties of DPPs near 1 AU based on nearly 20 years of observations from the WIND spacecraft. It is found that only a tiny fraction of DPPs (around 4.2%) can be regarded as interplanetary shocks. For most DPPs, the total pressure (the sum of the thermal pressure and magnetic pressure) remains in equilibrium, but there also exists a small fraction of DPPs that are not pressure-balanced. The overwhelming majority of DPPs are associated with solar wind disturbances, including coronal mass ejection-related flows, corotating interaction regions, as well as complex ejecta. The annual variations of the averaged occurrence rate of DPPs are roughly in phase with the solar activity during solar cycle 23, and during the rising phase of solar cycle 24.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: Granules observed in solar photosphere are believed to be convective and turbulent, but the physical picture of granular dynamical process remains unclear. Here we performed an investigation of granular dynamical motions of full length scales based on data obtained by the 1-meter New Vacuum Solar Telescope (NVST) and the 1.6-meter Goode Solar Telescope (GST). We developed a new granule segmenting method, which can detect both small faint and large bright granules. A large number of granules were detected and two critical sizes, 265 km and 1420 km, were found to separate the granules into three length ranges. The granules with sizes above 1420 km follow Gaussian distribution, and demonstrate "flat" in flatness function, which shows that they are non-intermittent and thus are dominated by convective motions. Small granules with sizes between 265 and 1420 km are fitted by a combination of power law function and Gauss function, and exhibit non-linearity in flatness function, which reveals that they are in the mixing motions of convection and turbulence. Mini granules with sizes below 265 km follow power law distribution and demonstrate linearity in flatness function, indicating that they are intermittent and strongly turbulent. These results suggest that a cascade process occurs: large granules break down due to convective instability, which transport energy into small ones; then turbulence is induced and grows, which competes with convection and further causes the small granules to continuously split. Eventually, the motions in even smaller scales enter in a turbulence-dominated regime.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-12
Abstract: Dynamic pressure pulses (DPPs) in the solar wind are a significant phenomenon closely related to the solar-terrestrial connection and physical processes of solar wind dynamics. In order to automatically identify DPPs from solar wind measurements, we develop a procedure with a three-step detection algorithm that is able to rapidly select DPPs from the plasma data stream and simultaneously define the transition region where large dynamic pressure variations occur and demarcate the upstream and downstream region by selecting the relatively quiet status before and after the abrupt change in dynamic pressure. To demonstrate the usefulness, efficiency, and accuracy of this procedure, we have applied it to the Wind observations from 1996 to 2008 by successfully obtaining the DPPs. The procedure can also be applied to other solar wind spacecraft observation data sets with different time resolutions.
Peer Review Status:Awaiting Review
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2023-11-10 Cooperative journals: 《中国全科医学》
Abstract: Background The number of chronic obstructive pulmonary disease (COPD) patients in China is huge, and respiratory rehabilitation training, as an important part of the management of COPD patients in the stabilization period, can effectively improve their lung function and quality of life, as well as reduce the burden on their families and society. Current data from Europe and the United States have shown that the implementation of respiratory rehabilitation under telemedicine management can improve the lung function and QOL of patients, however, there is a lack of relevant practice in China, especially in the west. Objective To assess the impact of respiratory rehabilitation training via telemedicine management in combination with conventional therapy on improving ventilatory capacity and lung function in elderly patients with moderateto-severe COPD. Methods This study was a prospective randomized controlled study, enrolling consecutive COPD patients who attended the Fourth Hospital of Sichuan Province and five joint community clinics from June 2021 to June 2022. The included patients were randomly divided into the experimental group and control group by simple randomized grouping method using random number table. The control group received traditional long-term regular inhalation bronchodilator and oral medication, and the experimental group was guided by telemedicine on the basis of the treatment plan of the control group. A six-month study was conducted on two groups of patients, lung function, Borg score, 6MWT, and quality of life score(QOL score) were recorded at 1 month before and 1, 3, 6 months after intervention. Results The study subjects were divided into 72 cases in the control group and 73 cases in the experimental group, and there was no significant difference in gender, age and lung function at baseline[the forced expiratory volume in one second/predicted value ratio(FEV1%pred), and the ratio of the forced expiratory volume in one second to the forced vital capacity(FEV1/FVC)] between the two groups(P>0.05). There was an interaction between time and group for dyspnea and mood in FEV1%pred, FEV1/FVC, 6MWT level and QOL score(P<0.05). After 1, 3, and 6 months of intervention, FEV1%pred, FEV1/FVC, 6MWT, Borg score, and QOL score of the experimental group were better 1 / 12GENERAL PRACTICE IN CHINAthan those of the control group, and the difference was statistically significant(P<0.05);FEV1%pred, FEV1/FVC,Borg score, 6MWT, and QOL scores at 3 and 6 months post-intervention were better than those at 1 month post#2;intervention in the experimental group(P<0.05). Conclusion The use of telemedicine technology for respiratory rehabilitation of elderly moderate-to-severe COPD patients in the stable stage can effectively improve the pulmonary function, quality of life and the quality of survival of this group of patients.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: In the manuscript, we discuss properties of the SDSS J1042-0018 which is a broad line AGN but mis-classified as a HII galaxy in the BPT diagram (SDSS J1042-0018 called as a mis-classified broad line AGN). The emission lines around H$\alpha$ and around H$\beta$ are well described by different model functions, considering broad Balmer lines to be described by Gaussian or Lorentz functions. Different model functions lead to different determined narrow emission line fluxes, but the different narrow emission line flux ratios lead the SDSS J1042-0018 as a HII galaxy in the BPT diagram. In order to explain the unique properties of the mis-classified broad line AGN SDSS J1042-0018, two methods are proposed, the starforming contributions and the compressed NLRs with high electron densities near to critical densities of forbidden emission lines. Fortunately, the strong starforming contributions can be preferred in the SDSS J1042-0018. The mis-classified broad line AGN SDSS J1042-0018, well explained by starforming contributions, could provide further clues on the applications of BPT diagrams to the normal broad line AGN.
Peer Review Status:Awaiting Review
Subjects: Biology >> Ecology submitted time 2023-08-15 Cooperative journals: 《干旱区科学》
Abstract:Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs. The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements, namely nitrogen (N) and phosphorus (P). Nevertheless, the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood. Therefore, we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment. Nine fertilization treatments with complete interactions of high, medium, and low N and P gradients were set up. Soil physical and chemical properties, along with the microbial community structure were measured in this study. Additionally, relevant ecological processes such as microbial biomass, respiration, N mineralization, and enzyme activity were quantified. To elucidate the relationships between these variables, we examined correlation-mediated processes using statistical techniques, including redundancy analysis (RDA) and structural equation modeling (SEM). The results showed that the addition of N alone had a detrimental effect on soil microbial biomass, mineralized N accumulation, and -1,4-glucosidase activity. Conversely, the addition of P exhibited an opposing effect, leading to positive influences on these soil parameters. The interactive addition of N and P significantly changed the microbial community structure, increasing microbial activity (microbial biomass and soil respiration), but decreasing the accumulation of mineralized N. Among them, N24P12 treatment showed the greatest increase in the soil nutrient content and respiration. N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid (PLFA) content by 70.93%. N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes. Soil microbial biomass, respiration, and overall enzyme activity are driven by mineralized N. Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract: In this paper we showed a systematic method of appropriate parameter choice for a circular pp collider by using analytical expression of beam-beam tune shift limit started from given design goal and technical limitations. A parameter space has been explored. Based on parameters scan and considerations from RF systems, a set of appropriate parameter designed for a 50Km and a 100Km circular proton-proton collider was proposed.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-08-30
Abstract: WIMPs are a well-motivated galactic dark matter candidate. Liquid argon (LAr) is an attractive target for the direct detection of WIMPs. The LAr prototype detector is designed to study the technology and property of LAr detector. The prototype detector have an active volume containing 0.65 kg of liquid argon. The liquid nitrogen(LN) cooling system allows the temperature of liquid argon to be maintained at the boiling point (87.8 K) with fluctuations less than 0.1 K. The prototype was calibrated with a Na22 source, with the light yield 1.591�.019 p.e./keV for the 511 keV gamma rays using the domestic-made argon purification system.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-11
Abstract: Luminance and contrast are two major attributes of objects in the visual scene. Luminance and contrast information received by visual neurons are often updated simultaneously. We examined the temporal response properties of neurons in the primary visual cortex (V1) to stimuli whose luminance and contrast were simultaneously changed by 50 Hz. We found that response tuning to luminance changes precedes tuning to contrast changes in V1. For most V1 neurons, the onset time of response tuning to luminance changes was shorter than that to contrast changes. Most neurons carried luminance information in the early response stage, while all neurons carried both contrast and luminance information in the late response stage. The early luminance response suggests that cortical processing for luminance is not as slow as previously thought.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-11
Abstract: Human gamma herpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are capable of inducing tumors, particularly in in immune-compromised individuals. Due to the stringent host tropism, rodents are resistant to infection by human gamma herpesviruses, creating a significant barrier for the in vivo study of viral genes that contribute to tumorigenesis. The closely-related murine gamma herpesvirus 68 (gamma HV68) efficiently infects laboratory mouse strains and establishes robust persistent infection without causing apparent disease. Here, we report that a recombinant gamma HV68 carrying the KSHV G protein-coupled receptor (kGPCR) in place of its murine counterpart induces angiogenic tumors in infected mice. Although viral GPCRs are conserved in all gamma herpesviruses, kGPCR potently activated downstream signaling and induced tumor formation in nude mouse, whereas gamma HV68 GPCR failed to do so. Recombinant gamma HV68 carrying kGPCR demonstrated more robust lytic replication ex vivo than wild-type gamma HV68, although both viruses underwent similar acute and latent infection in vivo. Infection of immunosuppressed mice with gamma HV68 carrying kGPCR, but not wild-type gamma HV68, induced tumors in mice that exhibited angiogenic and inflammatory features shared with human Kaposi's sarcoma. Immunohistochemistry staining identified abundant latently-infected cells and a small number of cells supporting lytic replication in tumor tissue. Thus, mouse infection with a recombinant gamma HV68 carrying kGPCR provides a useful small animal model for tumorigenesis induced by a human gamma herpesvirus gene in the setting of a natural course of infection.
Peer Review Status:Awaiting Review
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2017-05-02
Abstract: Poly[vinylidene fluoride] [PVDF] membranes have been widely applied to treat wastewater, however, the removal of toxic aromatic phenolic compounds remains a technical challenge due to the serious adsorption fouling and difficult degradation. Herein, we ai
Peer Review Status:Awaiting Review