Scattering of Ultra-relativistic Electrons in the Van Allen Radiation Belts Accounting for Hot Plasma Effects.

Electron flux in the Earth's outer radiation belt is highly variable due to a delicate balance between competing acceleration and loss processes. It has been long recognized that Electromagnetic Ion Cyclotron (EMIC) waves may play a crucial role in the loss of radiation belt electrons. Previous theoretical studies proposed that EMIC waves may account for the loss of the relativistic electron population. However, recent observations showed that while EMIC waves are responsible for the significant loss of ultra-relativistic electrons, the relativistic electron population is almost unaffected. In this study, we provide a theoretical explanation for this discrepancy between previous theoretical studies and recent observations. We demonstrate that EMIC waves mainly contribute to the loss of ultra-relativistic electrons. This study significantly improves the current understanding of the electron dynamics in the Earth's radiation belt and also can help us understand the radiation environments of the exoplanets and outer planets

The research progress of endocrine therapy combined with targeted therapy for triple-positive breast cancer

Triple-positive breast cancer (TPBC) refers to breast cancer with positive expression of estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 (HER2), accounting for 5%-10% of all pathological types of breast cancer. TPBC is a special subtype of Luminal B breast cancer, which can receive both endocrine therapy and targeted therapy. TPBC is a special subtype of Luminal B breast cancer, which can receive both endocrine therapy and targeted therapy. The current guidelines recommend that anti-HER2-targeted therapy combined with chemotherapy is the first choice for TPBC treatment. However, the pathological complete response rate of TPBC is lower than that of hormone receptor negative/HER2-positive breast cancer. Moreover, patients with estrogen receptor expression >30% benefit less from anti-HER2-targeted therapy combined with chemotherapy. With the advent of various anti-HER2 targeted drugs and the clinical application of cyclin-dependent kinase 4 and 6 inhibitors, the combination of targeted therapy and endocrine therapy becomes possible for highly selected patients. This article reviewed the research progress of TPBC endocrine therapy combined with targeted therapy

Identification and control of a Pseudomonas spp (P. fulva and P. putida) bloodstream infection outbreak in a teaching hospital in Beijing, China

SummaryObjectivesAn outbreak of bacteremia caused by Pseudomonas spp (P. fulva and P. putida) was first identified in our hospital in the summer of 2010 and reoccurred in the following year. Based on the epidemiological data collected in these 2 years, we initiated an investigation on the source of the outbreak. The aim of this study was to report the results of the investigation, as well as the intervention strategies that resulted in successful control of the outbreak.MethodsAn infection control team was set up consisting of infectious disease specialists, microbiologists, infection control practitioners, and head nurses. The microbiology and medical records of case-patients with P. fulva or P. putida bloodstream infections were reviewed. Environmental samples and intravenous (IV) solutions from the wards and the pharmacy center were collected for culturing. The molecular characteristics of the bacterial isolates were studied by pulsed-field gel electrophoresis (PFGE). Strict infection control strategies were implemented.ResultsA total of 20 case-patients from five inpatient wards were identified during three summer seasons from 2010 to 2012. Nineteen of them recovered with proper antibiotics. Unfortunately one died from complications of heart failure. A total of 19 isolates of P. fulva and four of P. putida were identified, of which 20 were from blood, two from environmental surface samples from the hospital pharmacy, and one from an in-use compounded solution from a case-patient in the cardiology ward. Molecular analysis revealed that the P. fulva isolated from the in-use compounded solution (5% glucose solution containing insulin, isosorbide dinitrate, and potassium magnesium aspartate) and the environmental samples had the same PFGE type as the clinical isolates.ConclusionsThe investigation identified that contaminated IV solution was the source of the P. fulva bacteremia, which prompted us to implement intensified control measures that resulted in successful control of the outbreak

Research on Flow Characteristics of Electronically Controlled Injection Device Developed for High-Power Natural Gas Engines

Accurate fuel supply is a key factor that influences the performance of high-power natural gas engines. The premixed and single-point natural gas supply system is the most commonly used method to ensure a large fuel supply but one of its shortcomings is the inaccuracy of the fuel supply. A new type of natural gas injection device with fungiform configuration and electronically controlled actuator was developed to achieve high efficiency and stable operation in high-power natural gas engines. Firstly, a computational fluid dynamics (CFD) model of the injection device was created. Based on this model, the key structure parameters that have a significant influence on the outlet flow were confirmed. A particle swarm optimization (PSO) model was developed to identify the optimal outflow structure. Then, a flow function for precise flow supply control was constructed based on a response surface model, according to the flow rates of the device under different control parameters. Finally, a flow-characteristic test bench and a high-power engine prototype were developed to verify the simulation and optimization results. The results indicate that the optimized outflow structure shows low pressure loss and a large flow rate, improving injection efficiency by 10.37% and mass flow by 11.78% under 0.4 Mpa pressure difference. More importantly, the cycle fuel supply could be controlled accurately for each cylinder owing to the developed flow function. Consequently, compared with the original engine using a single-point natural gas supply system, the cylinder performance imbalance was improved by 37.47%

The beauty in imperfection: how naturalness cues drive consumer preferences for ugly produce and reduce food waste

PurposeAn important reason for food waste is the rejection of ugly produce by consumers. Most previous research has examined the absolute negative impacts of ugly produce on consumers’ preferences, no research has examined the conditions in which consumers prefer ugly (vs. typical) produce instead.This research investigates the circumstances under which these aesthetic imperfections become advantageous.MethodsWe conducted two between-subject design randomized experiments featuring two produce categories to examine when and why consumers prefer ugly produce.ResultsWe found that naturalness cues boost and even reverse consumers’ preferences for ugly produce when combining ugly appearance with naturalness cues. The subtyping effect mediates the interaction of appearance (typical vs. ugly) of produce and naturalness cues (present vs. absent) on produce’s evaluations.DiscussionOur findings provide more cost-effective strategies for retailers to reduce food waste. This paper fills in the research gaps on taping into the novel condition in which consumers prefer ugly (vs. typical) produce and the psychological mechanism behind this process. Based on schema incongruity theory, we argue that naturalness cues, as an enabler corresponding to the incongruous features of ugly produce, facilitate consumers to resolve the schema incongruity triggered by the ugly appearance and, in turn, boost consumers’ preferences for ugly produce

Mutation analysis of the WNT4 gene in Han Chinese women with premature ovarian failure

BACKGROUND: The WNT4 gene plays an important role in female sex determination and differentiation. It also contributes to maintaining of the ovaries and the survival of follicles. METHODS: We sequenced the coding region and splice sites of WNT4 in 145 Han Chinese women with premature ovarian failure (POF) and 200 healthy controls. RESULTS: Only one novel variation, in Exon 2 (195C > T), was detected among the women with POF. However, this synonymous variation did not result in a change in amino acid sequence (65 Asp > Asp). No further variants were found in any of the samples. CONCLUSION: Although we cannot provide any evidence that it is a possible disease-causing gene, this study is the first attempt to investigate the possible role of WNT4 in Han Chinese women with POF

Influence of Prewhirl Regulation by Inlet Guide Vanes on Cavitation Performance of a Centrifugal Pump

The influence of prewhirl regulation by inlet guide vanes (IGVs) on a centrifugal pump performance is investigated experimentally and numerically. The experimental results show that IGVs can obviously change the head and increase the efficiency of the tested centrifugal pump over a wide range of flow rates. Although the cavitation performance is degraded, the variation of the cavitation critical point is less than 0.5 m. Movement of the computed three-dimensional streamlines in suction pipe and impeller are analyzed in order to reveal the mechanism how the IGVs realize the prewhirl regulation. The calculated results show that the influence of IGVs on the cavitation performance of centrifugal pump is limited by a maximum total pressure drop of 1777 Pa, about 7.6% of the total pressure at the suction pipe inlet for a prewhirl angle of 24°

Magnetospheric formation processes of the diffuse aurora

Resonant wave-particle interactions in the Earth's magnetosphere can lead to the scattering of plasma sheet electrons which in turn cause the optical phenomenon of diffuse aurora. Specifically, electrostatic electron cyclotron harmonic (ECH) waves can effectively precipitate hundreds of eV to tens of keV electrons into the upper atmosphere. This process can generally be treated as a diffusion problem, requiring the numerical calculation of bounce-averaged quasi-linear diffusion coefficients. ECH waves are thought to be generated by the loss cone instability of the ambient hot electron distribution. Therefore, the determination of ECH wave-induced scattering rates requires information about the properties of the hot plasma sheet electrons responsible for the wave excitation. We report our progress on analysing the sensitivity of ECH wave-induced electron scattering effects to the temperature of the hot electron components, which has an influence on the growth rate of the waves

Dependence of ECH wave-induced scattering rates on the electron distribution

Through resonant wave-particle interactions with electrostatic electron cyclotron harmonic (ECH) waves, low-energy (100s of eV to 10s of keV) plasma sheet electrons can be scattered into the atmospheric loss cone and contribute to diffuse auroral precipitation. This process consequently influences the evolution of the electron phase space density, but is currently not included in numerical codes simulating the radiation belt dynamics. In order to describe the ECH wave-induced electron scattering process, bounce-averaged quasi-linear diffusion coefficients need to be calculated. As ECH waves are thought to be generated by the loss cone instability of the ambient hot electron distribution, the numerical calculation of ECH wave-induced scattering rates requires the specification of the wave propagation characteristics, the background magnetic field and plasma density as well as properties of the hot plasma sheet electrons responsible for the wave excitation. In this study, we analyze the dependence of the bounce-averaged quasi-linear scattering rates by ECH waves on the temperature of the hot electron components in the electron distribution. By assuming the background plasma parameters based on previous observations, scattering rates are computed for hot electron temperatures varying from hundreds of eV to several keV, which is consistent with observations as well. A wave power spectral profile based on statistical wave properties is assumed and used to calculate weighted diffusion coefficients. We find that the hot electron temperature influences the growth rate and wave normal angle distribution of the waves, changing the pitch angle diffusion coefficients and lifetimes of the electrons near the loss cone