This study utilizes data from a 3D lightning location system,polarimetric radar,and current measurements from channels of triggered lightning flashes(TLFs)to analyze the structural characteristics of the parent thunde...This study utilizes data from a 3D lightning location system,polarimetric radar,and current measurements from channels of triggered lightning flashes(TLFs)to analyze the structural characteristics of the parent thunderstorms associated with negative TLFs in South China.The triggered-flash region(TFR)displays distinct stratiform cloud characteristics,including lower radar reflectivity heights and a predominance of ice crystals and dry snow above the 0℃ layer.In contrast,the thunderstorm convection core region(CCR)tends to have more graupel particles in the mixed-phase layers and exhibits an ice-water content peak approximately 3.4 times that of the TFR.The charge regions involved in discharges in TFRs exhibit a dipolar charge structure,with the-5℃ layer roughly dividing the upper positive and lower negative charge regions.Conversely,the CCRs feature a typical tripolar charge structure.The dominant dipole charge structure in the TFR results in an increase in the negative charge field below the negative charge region with height,providing a necessary condition for successfully triggering negative TLFs.Furthermore,the horizontal extent of TLFs is positively correlated with their duration and charge transfer.Regions where TLF channels with larger charge transfers propagate tend to have greater maximum radar reflectivity but lower average radar reflectivity compared to regions with TLFs with smaller charge transfer.展开更多
Objective：To evaluate the effect of Chinese herbs decoction Shu-Gan-Liang-Xue on endocrine therapy-associated hot flashes symptom in breast cancer patients.Methods：Sixty-six patients with breast cancer receiving adj...Objective：To evaluate the effect of Chinese herbs decoction Shu-Gan-Liang-Xue on endocrine therapy-associated hot flashes symptom in breast cancer patients.Methods：Sixty-six patients with breast cancer receiving adjuvant endocrine therapy were categorized to two groups,the control group received endocrine therapy alone,the other group is administered with Chinese herbs decoction Shu-Gan-Liang-Xue besides the endocrine therapy：Shu-Gan-Liang-Xue decoction was administered above 6 months per year for more than 2 years.Frequency of hot flashes per day was recorded,and the effect of Shu-Gan-Liang-Xue decoction on hot flashes symptom being assessed with Kupperman Scoring Index.Results：Sixty cases were analyzed,32 cases in endocrine therapy combining Chinese herbs decoction group,28 cases in mere endocrine therapy group.For hot flashes symptom,in Chinese herbs decoction administration group,7 cases（21.9%） reported symptom disappeared,22 cases（68.7%） reported symptom alleviated,3 cases（9.4%） reported symptom not changed;in endocrine therapy alone group,5 cases（17.9%） reported symptom disappeared,13 cases（46.4%） reported symptom alleviated,10 cases（10/28,35.7%） reported symptom not changed.The difference between two groups was statistically significant（P=0.013）.For sleeping disorder,in Chinese herbs decoction administration group,27 cases（84.4%） reported symptom improved,5 cases（15.6%） reported no change;in endocrine therapy alone group,16 cases（57.1%） symptom improved,12 cases（42.9%） reported no change in sleeping disorder（P=0.019）,the difference was also of significance statistically.Conclusion：Long-term Chinese herbs decoction administration remarkably improved hot flashes symptom and sleeping disorder associated with endocrine therapy,meanwhile without definite toxicity and influence on the risk of recurrence of tumor.展开更多
Breast cancer (BC) is the most common malignant tumor in women. Around 50% of BC receptor-positive patients are hormone-dependent cases, and it is necessary for them to use endocrine after operation. Through inhibitio...Breast cancer (BC) is the most common malignant tumor in women. Around 50% of BC receptor-positive patients are hormone-dependent cases, and it is necessary for them to use endocrine after operation. Through inhibition of estrogen level展开更多
Over twenty thousand lightning location data obtained by using Lightning Location System(LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The...Over twenty thousand lightning location data obtained by using Lightning Location System(LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The strength of positive flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negative flashes in Beijing and in Lanzhou respectively. It has been found that the strength of positive and negative flashes is submitted to the normal distribution, and is independent of the characteristics of thunderstorm. So the lightning strength obtained by DF may be used to forecast the coming of thunderstorm. Although the stroke number in both regions decreases as exponent regulation, the maximum number of return stroke for one lightning in Beijing is more than that in Lanzhou. The peak flash rate occurs in late afternoon for both regions, but the maximum and minimum flash rate appeared an hour earlier in Beijing than in Lanzhou.The relationship between DF display and lightning radiation electric field, discharge current is obtained.展开更多
PURPOSE: To test the safety and efficacy of acupuncture in reducing hot flashes in men with advanced prostate cancer (CaP) undergoing androgen deprivation therapy. METHODS: A single-arm, pilot study was undertaken to ...PURPOSE: To test the safety and efficacy of acupuncture in reducing hot flashes in men with advanced prostate cancer (CaP) undergoing androgen deprivation therapy. METHODS: A single-arm, pilot study was undertaken to evaluate acupuncture treatment for hot flashes experienced by CaP patients undergoing hormonal therapy. Sixteen advanced CaP patients undergoing androgen deprivation therapy (ADT) received standardized full body and auricular acupunc-ture 1x/week for 14 weeks. Patients were evaluated at 0, 7, 14, and an additional 14-wk follow-up (F/U) (28-wks). Safety was measured by monitoring for adverse events over the treatment period. Serum testosterone was measured at 0 and 14-wks. Quality of life (QOL) was measured by the hormone domain of the Expanded Prostate Index Composite (EPIC), at the 0, 7, 14, and 28-wks and patient reported hot flash frequency was assessed weekly. Safety endpoints were serum testosterone and analysis of adverse events. Efficacy endpoints were scores on the EPIC and the number of pa-tient reported hot flashes. RESULTS: 17 patients were enrolled and 15 completed the trial. Of 15 evaluable patients the median age was 68 ± 8.19. Serum analysis demonstrated no change in testosterone at baseline 9.5 ng/ml ± 8.9 vs. end-point 14 ± 8.78 (p = 0.101). No adverse events were reported. Data analysis of the EPIC demonstrated a trend toward improvement after 7 wks and a significant improvement following 14 wks of acupuncture (p = 0.01). Analysis of patient reported frequency showed a significant reduction in the number of hot flashes at 7-wk (6, p = 0.04), 14-wk (2.6, p = 0.001), and 28-wk F/U (3.2, p = 0.01) as compared to baseline 9.57 ± 3.98. CONCLUSIONS: The administration of acupuncture in men with advanced CaP appears to significantly decrease the frequency of hot flashes. No serious ad-verse events were noted and serum testosterone levels were unchanged from baseline suggesting that the mechanism of action of acupuncture for hot flash amelioration is not via increase in testosterone.展开更多
Background:Hot flashes are one of the most common symptoms in menopause and significantly affect the quality of life of 67% of menopausal women.Acupuncture is found to be a low risk treatment in treating hot flashes b...Background:Hot flashes are one of the most common symptoms in menopause and significantly affect the quality of life of 67% of menopausal women.Acupuncture is found to be a low risk treatment in treating hot flashes but the evidence for its effectiveness is inconclusive.We developed an optimized acupuncture treatment protocol and designed a randomized controlled trial(RCT) to assess the efficacy of acupuncture for reducing hot flashes in menopausal women.Methods:This is a single-site,single-blind,randomized sham-controlled trial with two parallel arms.A total of 60 eligible patients will be recruited and randomly assigned to either the acupuncture group(n=30) or the sham acupuncture group(n=30).Treatment will be given twice a week,for 30 min,for six consecutive weeks.The primary outcome is the hot flashes scores,assessed using the validated hot flashes diary at baseline,week 3,week 6 and week 10.The secondary outcome will be measured by menopause-specific quality of life(MENQOL) at baseline,week 6,and week 10.Meanwhile,any adverse events will be recorded.Discussion:If the outcome of this study confirms acupuncture to be an effective therapy to reduce hot flashes in menopausal women,we expect this study to inspire further investigations and provide useful information in forming an optimal acupuncture treatment protocol for clinic.Trial registration:Chinese Clinical Trial Registry identifier:ChiCTR1800018638,Date of registration:30 th September 2018.URL:http://www.chictr.org.cn/showproj.aspx?proj=31462.展开更多
Objective:To compare the therapeutic effect on menopausal hot flashes between acupuncture and Climen so as to provide a new approach to the treatment of this disease.Methods:A total of 80 cases in line with inclusion ...Objective:To compare the therapeutic effect on menopausal hot flashes between acupuncture and Climen so as to provide a new approach to the treatment of this disease.Methods:A total of 80 cases in line with inclusion criteria were randomized into a treatment group(treated with acupuncture) and a control group(oral administration with climen),40 cases in each one.The treatment for 1 month was as 1 course and lasted consecutively for 2 courses.Before and after treatment,the contents of serum estrogen(estradiol,E_(2)) and 5-hydroxytryptamine(HT) and the scores of the attack frequency and severity scale of hot flashes and sweating,domestic modified Kupperman scale and traditional Chinese medicine(TCM) symptom scale were observed,and the clinical therapeutic effect was evaluated in the two groups separately.Results:Before treatment,there was no difference in the content of E_(2) and 5-HT,the score of hot flashes and sweating,Kupperman score and TCM symptom score in the patients between two groups,indicating the comparability(all P>0.05).Compared with the data before treatment,the contents of serum E_(2)(treatment group vs control group:22.24±11.02 vs 33.12±1.01;22.11±10.19 vs 25.29±2.23) and5-HT(treatment group vs control group:96.12±8.21 vs 131.21±30.21;96.98±7.99 vs 108.29±22.08),the score of hot flashes and sweating(treatment group vs control group:8.24±1.02 vs 3.12±1.01;8.11±1.19 vs 5.29±2.23),Kupperman score(treatment group vs control group:26.12±2.21 vs11.21±0.21;26.98±1.99 vs 18.29±2.08) and TCM symptom score(treatment group vs control group:18.97±3.87 vs 10.12±0.16;19.01±2.29 vs 15.61±2.89) were statistically different after treatment in the two groups(all P<0.05).After treatment,the contents of serum E_(2) and 5-HT,the score of hot flashes and sweating,Kupperman score and TCM symptom score in the treatment group were all different statistically compared with the control group(all P<0.05).There was statistical difference in clinical therapeutic effect in the patients between two group,in which,the therapeutic effect in the treatment group was better than that in the control group(90% vs 77.5%,P<0.05).Conclusion:Acupuncture effectively reduces Kupperman score and TCM symptom score in the patients and its therapeutic effect is better than climen.Regarding relieving hot flashes symptoms in menopausal patients of kidney yin deficiency and improving in attack frequency and severity of hot flashes and sweating,the effects of acupuncture are superior to Climen.Acupuncture obviously increases the contents of serum E_(2) and 5-HT.展开更多
By the 3D coupled thermo-mechanical finite element model of linear friction welding of TC4 titanium alloy, the relation between the temperature and the flashes is researched. The numerical simulation results show that...By the 3D coupled thermo-mechanical finite element model of linear friction welding of TC4 titanium alloy, the relation between the temperature and the flashes is researched. The numerical simulation results show that the flashes with the wrinkles appear only when the temperature of material in the friction surface is high enough. The flashes, which are made up of material with high temperature, are squeezed out of the component. The appearance of flashes makes the temperature of material in the friction susface slowly increase or even decrease. Compared with the oscillation frequency and the oscillation amplitude, the friction pressure＇ s increase can mare easily attain the flashes with the bigger dimensionz.展开更多
On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are ...On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are investigated. The results of numerical simulation show that the temperature of friction surface is higher than that of other region and the peak temperature increases with the increase of welding time. During the process of friction stage, no flash appears because of the low temperature and the small axial friction pressure. At the forging stage, the flashes appear, whose dimensions and bending degree increase with the increase of welding temperature. Moreover, with the increase of rotational velocity and axial forging pressure, the dimensions and the bending degree of flashes of continuous drive friction welding increase.展开更多
Purpose: Hormone therapy (estrogen with or without progestin) remains the gold standard treatment for hot flashes in menopausal women, but concerns for the risk of hormone therapy have resulted in its decline and a de...Purpose: Hormone therapy (estrogen with or without progestin) remains the gold standard treatment for hot flashes in menopausal women, but concerns for the risk of hormone therapy have resulted in its decline and a demand for nonhormonal treatments with demonstrated efficacy for hot flashes. Aim of this study was to examine the efficacy of selective serotonin reuptake inhibitor escitalopram on hot flashes in a healthy sample of non-depressant menopausal women in Japan. Methods: We retrospectively analyzed the medical records of 11 menopausal patients with hot flashes, who received escitalopram (10 mg daily) for 2 weeks between March and August 2012. Hot flashes severities and scores were recorded on a scale of 0 to 10 points, at beginning and end of 2 weeks treatment. Results: At 2 weeks of therapy, 9 of 11 patients reported significant decreases in hot flash frequency and severity, but the remission of the symptom was not observed in 2 patients. Speed of relief from hot flashes was rapid (within one week). Conclusions: Escitalopram 10 mg/day may be a prompt and effective option for treating hot flashes in menopausal women who do not want to use hormone replacement therapy.展开更多
This study examined the effects of caffeine, alcohol, and physical activity (PA) on the perceived frequency and severity of hot flashes in menopausal women. Female employees at a Mid-Western university were invited to...This study examined the effects of caffeine, alcohol, and physical activity (PA) on the perceived frequency and severity of hot flashes in menopausal women. Female employees at a Mid-Western university were invited to participate in an on-line survey. The 26-itemized Wo- men’s Health Survey (WHS) included questions regarding demographics, menopausal stage, experience of hot flashes, consumption of caffeinated beverages and alcohol, and participation in PA. One-hundred and ninety-six women completed the study. Ordinary Least Squares regressions revealed PA, caffeine, and alcohol intake were significant in predicting the severity of hot flashes (R2 = 0.068, F(6,180) = 2.195, p = 0.046), though they did not predict frequency of hot flashes (R2 = 0.043, F(6,184) = 1.39, p = 0.221). Participation in aerobic PA increased frequency of hot flashes (p = 0.031);while higher intensity of aerobic PA had an inverse relationship on both frequency and severity of hot flashes (p = 0.011, p = 0.003, respectively). Spearman correlations demonstrated a positive relationship between caffeinated soda intake and frequency (r = 0.17, p = 0.06) and severity (r = 0.19, p = 0.04) of hot flashes. Beverage consumption and PA may predict severity of hot flashes in women. Less frequent, higher intensity aerobic PA may lead to fewer, less severe hot flashes.展开更多
Women worldwide are dealing with hot flashes (潮热), a perimenopausal feature that is often tiring,embarrassing, and energeticallydraining. Conventionally, Chinese medicine defines hot flashes as Kidney-yin deficiency...Women worldwide are dealing with hot flashes (潮热), a perimenopausal feature that is often tiring,embarrassing, and energeticallydraining. Conventionally, Chinese medicine defines hot flashes as Kidney-yin deficiency and its clinical manifestations include red face,sweating, hot sensations in the palms and soles, mouth and nose dryness, constipation, insomnia, lumbar soreness, knee weakness, redtongue, etc. To obtain a broader perspective and understand the dynamics of hot flashes, we examined the mechanisms behind hot flashesbased on both the knowledge from ancient Chinese medicinal texts, as well as novel research findings of Chinese and Western medicine.This perspective was the foundation for the acupuncture study of our traditional Chinese medicine conducted in 2018-2019 in Shanghai.This study, designed as a pragmatic randomized control trial with two parallel groups, focused on regulating and unblocking conceptionand governor vessels. The results confirmed that our acupuncture method could effectively reduce both the frequency and severity of hotflashes and improve life quality of middle-aged women.展开更多
The aim of this study was to evaluate the effectiveness of a pharmaceutical grade isoflavone supplement (Inoclim?) 40 mg per capsule of soy extract rich in daidzin and genistin) on the number of hot flashes and night ...The aim of this study was to evaluate the effectiveness of a pharmaceutical grade isoflavone supplement (Inoclim?) 40 mg per capsule of soy extract rich in daidzin and genistin) on the number of hot flashes and night sweats in menopausal African women. This open, prospective, multicenter study involved 140 menopausal women with climacteric symptoms (i.e., a minimum of five hot flashes and/or moderate to severe night sweats per day). These patients received a daily 40-mg supplement of soy isoflavone contained in an Inoclim? capsule (Laboratoire Innotech International, France). The dose was increased to two capsules per day when there were more than five hot flashes or when the women could not sleep because of night sweats. The patients were followed up over a 4-month period and data were analyzed using EPI-InfoTM version 3.5.1. The outcome measure was fewer hot flashes and night sweats. The mean daily number of episodes of hot flashes was 5.7 at baseline and 1.8 at week 16, corresponding to a decrease of 68.4% (n = 93 patients at baseline and n = 66 at 16 weeks). The mean number of daily episodes of night sweats was 3.7 at baseline and 0.8 at week 16, corresponding to a decrease of 78.4% (n = 127 patients in the first week and n = 73 at 16 weeks). Over 80% of patients took a single one 40 mg capsule per day. The percentage of patients who adhered to the prescription was more than 95% during the 4-month follow-up period. These results confirm the effectiveness of a pharmaceutical grade isoflavone supplement (40 mg, rich in genistin and daidzin) on vasomotor symptoms in menopausal women.展开更多
The electrical characteristics of thunderstorms in three different altitude regions of the Chinese inland plateau have been analyzed in this paper. The results show, according to the polarity of the surface electric ...The electrical characteristics of thunderstorms in three different altitude regions of the Chinese inland plateau have been analyzed in this paper. The results show, according to the polarity of the surface electric （E） field, that the thunderstorms can be divided into two categories in the study regions： one showing the normal tripole electrical charge structure （normal-type）, and the other showing the special tripole charge structure with a larger-than-usual lower positive charge center （LPCC） at the base of thunderstorm （special-type）, where the induced surface E field is controlled by the LPCC when a thunderstorm is overhead. We find that the two types of thunderstorms have different occurrences in different regions, and the percentage of special-type thunderstorms increases with the altitude. On the whole, the flash rate of thunderstorms is quite low, and the mean value is about 1-3 fl/min, while the flash rate of special-type is slightly greater than that of the normal-type thunderstorm. The statistical results of cloud-to-ground flash （CG） numbers indicate that the ratio of ＋CG flash increases with the altitude, with the value about 14.7 percent through 25.4 percent.展开更多
We establish a system to measure the functional absorption cross section of photosystem lI （PSII） （O-PSII） and maximum quantum yield of photochemistry in PSII （Fv/Fm）. The system utilizes a sequence of high-freq...We establish a system to measure the functional absorption cross section of photosystem lI （PSII） （O-PSII） and maximum quantum yield of photochemistry in PSII （Fv/Fm）. The system utilizes a sequence of high-frequency excitation flashes at microsecond intervals to induce a microsecond-level fluorescence yield curve. Parameters o-Psii and Fv/Fm are calculated by fitting the curve using nonlinear regression. Experimental results show that the relative standard deviation （RSD） of the system is less than 3%, and the correlation coefficient of Fv/Fm values measured by this system and those measured by pulse amplitude modulation method is 0.950.展开更多
Objective:To conduct a literature review of randomized controlled trials(RCTs)on the use of acupuncture for hot flashes to analyze the characteristics of each study,draw a conclusion on the advantages and disadvantage...Objective:To conduct a literature review of randomized controlled trials(RCTs)on the use of acupuncture for hot flashes to analyze the characteristics of each study,draw a conclusion on the advantages and disadvantages of previous studies and provide the suggestions for future studies on the same topic.Methods:We searched English and Chinese databases for the literature published from 2009 to 2019 restricted in the English and Chinese language,and we included RCT using acupuncture as the main observational intervention for hot flashes by the criteria.Results:Twenty studies met our eligibility criteria.All the studies were of high quality and confirmed the clinical efficacy of acupuncture for hot flashes,although they used different controlled interventions.The acupuncture treatment and theory of acupoints selection were relatively consistent among the studies,and they had close trial designs.Conclusions:These RCTs on acupuncture were nonuniform,which made the studies on this topic lack coherence,leading to unsatisfactory research outcomes.Therefore,more professional research teams are needed to perform studies on a definite topic and draw a specific conclusion to previous studies before the next step is taken.展开更多
Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a...Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a natural highenergy phenomenon associated with lightning discharges that frequently occur during thunderstorms.However,their production mechanisms and associated processes are still unclear.TGF studies have already been a research spotlight in the atmospheric electricity and high-energy atmosphere research areas.In this paper,we review recent research progresses on TGF studies in the past decade,including TGF detection,the relationship between TGFs and lightning processes,and thunderstorm activities.Several unsolved important scientific questions are discussed.Results suggest that upward TGFs observed by satellite-based detectors are closely connected with the development of in-cloud upward negative leaders.They are usually generated in milliseconds of the initiation of upward negative leaders and may produce a kind of distinct radio emissions because of the generation and propagation of huge amounts of high-energy electrons.By contrast,its counterpart,i.e.,downward TGFs observed by ground-based gamma-ray detectors,is associated with different types of lightning processes,such as downward negative or upward positive leaders,the initial continuing current stage of rocket-triggered lightning flashes return stroke processes.Because of limited observations,how these downward TGFs are generated is still unclear.Benefiting from the development of state-of-the-art instruments with high temporal and spatial resolutions,new insights into the processes and mechanisms of TGFs will be achieved with coordinated observations from satellite-based and ground-based measurements.展开更多
The mitochondria play essential roles in both intracellular calcium and reactive oxygen species signaling.As a newly discovered universal and fundamental mitochondrial phenomenon,superoxide flashes reflect transient b...The mitochondria play essential roles in both intracellular calcium and reactive oxygen species signaling.As a newly discovered universal and fundamental mitochondrial phenomenon,superoxide flashes reflect transient bursts of superoxide production in the matrix of single mitochondria.Whether and how the superoxide flash activity is regulated by mitochondrial calcium remain largely unknown.Here we demonstrate that elevating mitochondrial calcium either by the calcium ionophore ionomycin or by increasing the bathing calcium in permeabilized HeLa cells increases superoxide flash incidence,and inhibition of the mitochondrial calcium uniporter activity abolishes the flash response.Quantitatively,the superoxide flash incidence is correlated to the steady-state mitochondrial calcium elevation with 1.7-fold increase per 1.0?F/F0 of Rhod-2 signal.In contrast,large mitochondrial calcium transients(e.g.,peak△F/F0~2.8,duration^2 min)in the absence of steady-state elevations failed to alter the flash activity.These results indicate that physiological levels of sustained,but not transient,mitochondrial calcium elevation acts as a potent regulator of superoxide flashes,but its mechanism of action likely involves a multi-step,slow-onset process.展开更多
The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate...The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate a severe thunderstorm to permit analysis of the conditions that might easily cause +CG flashes. The results showed that strong updrafts play an important role in the occurrence of intracloud flashes. However, frequent +CG flashes require not only strong updrafts but also strong downdrafts in the lower cloud region, conditions that correspond to the later phase of the mature stage and the period of the heaviest solid precipitation of a thunderstorm. During this stage, strong updrafts elevated each charge area in the updraft region to a higher level, which resulted in an inverted tripole charge structure. A wide mid-level region of strong positive charge caused largely by positively charged graupel, presented in the middle of the updraft region because of a non-inductive ice-ice collisional charging mechanism. The charge structure in the downdraft region was consistently more complex and revealed several vertically stacked charge regions, alternating in polarity. Much of the graupel/hail outside the updrafts was lowered to cloud-base by strong downdrafts. In this area, the graupel/hail was charged negatively because of the transportation of negatively charged graupel/hail from higher regions of negative charge in the updrafts, and via the inductive charging mechanism of collisions between graupel/hail and cloud droplets at the bottom of the cloud. Consequently, a large region of negative charge formed near the ground. This meant that +CG flashes were initiated more easily in the lower inverted dipole, i.e., the middle region of positive charge and lower region of negative charge. Frequent +CG flashes began almost synchronously with dramatic increases in the storm updrafts, hail volume, and total flash rate. Therefore, the occurrence of +CG flashes appears a good indicator of storm intensification and it could have some use as a predictor of severe weather in the form of hail.展开更多
The authors present an analysis of different charge transfer modes during upward negative flashes.The analysis includes a total number of 94 pulses that occurred during two upward negative flashes recorded at the S...The authors present an analysis of different charge transfer modes during upward negative flashes.The analysis includes a total number of 94 pulses that occurred during two upward negative flashes recorded at the Säntis Tower.The pulses included 59 mixed-mode(MM)initial continuous current(ICC)pulses,17 M-component-type ICC(M-ICC)pulses,8 returnstroke pulses,and 10 classical M-component(MC)pulses.It is found that the initial stage of the flash is responsible for the largest share of the total charge transferred to the ground.Simulation results for the electric fields associated with the considered charge transfer modes are presented and discussed.Return stroke(RS)and MM pulses were simulated adopting the MTLE model,while MCs and M-ICC pulses were simulated using the guided wave model of Rakov et al.The simulated results are shown to be in good agreement with simultaneous records of electric fields measured at a distance of 15 km from the Säntis Tower.The inferred velocities for MCs and M-ICC pulses range from 2.0×10^(7) to 9.0×10^(7) m/s,and the corresponding junction point heights range from 1.0 to 2.0 km.The inferred pulse velocities for RSs and MM pulses range from 1.3×10^(8) to 1.65×10^(8) m/s.The inferred current attenuation constants of the MTLE model obtained in this study range from 0.3 to 0.8 km,lower than the value of 2 km previously suggested for RSs in downward flashes.The obtained results support the assumption that the mode of charge transfer to the ground giving rise to MM pulses is similar to that of RSs.The results are also in support of the generally assumed similarity between M-ICC pulses and classical MCs.展开更多
基金funded by the Natural Science Foundation of China(Grant No.U2342215)Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province(Grant No.SCSF202302)。
文摘This study utilizes data from a 3D lightning location system,polarimetric radar,and current measurements from channels of triggered lightning flashes(TLFs)to analyze the structural characteristics of the parent thunderstorms associated with negative TLFs in South China.The triggered-flash region(TFR)displays distinct stratiform cloud characteristics,including lower radar reflectivity heights and a predominance of ice crystals and dry snow above the 0℃ layer.In contrast,the thunderstorm convection core region(CCR)tends to have more graupel particles in the mixed-phase layers and exhibits an ice-water content peak approximately 3.4 times that of the TFR.The charge regions involved in discharges in TFRs exhibit a dipolar charge structure,with the-5℃ layer roughly dividing the upper positive and lower negative charge regions.Conversely,the CCRs feature a typical tripolar charge structure.The dominant dipole charge structure in the TFR results in an increase in the negative charge field below the negative charge region with height,providing a necessary condition for successfully triggering negative TLFs.Furthermore,the horizontal extent of TLFs is positively correlated with their duration and charge transfer.Regions where TLF channels with larger charge transfers propagate tend to have greater maximum radar reflectivity but lower average radar reflectivity compared to regions with TLFs with smaller charge transfer.
文摘Objective：To evaluate the effect of Chinese herbs decoction Shu-Gan-Liang-Xue on endocrine therapy-associated hot flashes symptom in breast cancer patients.Methods：Sixty-six patients with breast cancer receiving adjuvant endocrine therapy were categorized to two groups,the control group received endocrine therapy alone,the other group is administered with Chinese herbs decoction Shu-Gan-Liang-Xue besides the endocrine therapy：Shu-Gan-Liang-Xue decoction was administered above 6 months per year for more than 2 years.Frequency of hot flashes per day was recorded,and the effect of Shu-Gan-Liang-Xue decoction on hot flashes symptom being assessed with Kupperman Scoring Index.Results：Sixty cases were analyzed,32 cases in endocrine therapy combining Chinese herbs decoction group,28 cases in mere endocrine therapy group.For hot flashes symptom,in Chinese herbs decoction administration group,7 cases（21.9%） reported symptom disappeared,22 cases（68.7%） reported symptom alleviated,3 cases（9.4%） reported symptom not changed;in endocrine therapy alone group,5 cases（17.9%） reported symptom disappeared,13 cases（46.4%） reported symptom alleviated,10 cases（10/28,35.7%） reported symptom not changed.The difference between two groups was statistically significant（P=0.013）.For sleeping disorder,in Chinese herbs decoction administration group,27 cases（84.4%） reported symptom improved,5 cases（15.6%） reported no change;in endocrine therapy alone group,16 cases（57.1%） symptom improved,12 cases（42.9%） reported no change in sleeping disorder（P=0.019）,the difference was also of significance statistically.Conclusion：Long-term Chinese herbs decoction administration remarkably improved hot flashes symptom and sleeping disorder associated with endocrine therapy,meanwhile without definite toxicity and influence on the risk of recurrence of tumor.
文摘Breast cancer (BC) is the most common malignant tumor in women. Around 50% of BC receptor-positive patients are hormone-dependent cases, and it is necessary for them to use endocrine after operation. Through inhibition of estrogen level
文摘Over twenty thousand lightning location data obtained by using Lightning Location System(LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The strength of positive flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negative flashes in Beijing and in Lanzhou respectively. It has been found that the strength of positive and negative flashes is submitted to the normal distribution, and is independent of the characteristics of thunderstorm. So the lightning strength obtained by DF may be used to forecast the coming of thunderstorm. Although the stroke number in both regions decreases as exponent regulation, the maximum number of return stroke for one lightning in Beijing is more than that in Lanzhou. The peak flash rate occurs in late afternoon for both regions, but the maximum and minimum flash rate appeared an hour earlier in Beijing than in Lanzhou.The relationship between DF display and lightning radiation electric field, discharge current is obtained.
文摘PURPOSE: To test the safety and efficacy of acupuncture in reducing hot flashes in men with advanced prostate cancer (CaP) undergoing androgen deprivation therapy. METHODS: A single-arm, pilot study was undertaken to evaluate acupuncture treatment for hot flashes experienced by CaP patients undergoing hormonal therapy. Sixteen advanced CaP patients undergoing androgen deprivation therapy (ADT) received standardized full body and auricular acupunc-ture 1x/week for 14 weeks. Patients were evaluated at 0, 7, 14, and an additional 14-wk follow-up (F/U) (28-wks). Safety was measured by monitoring for adverse events over the treatment period. Serum testosterone was measured at 0 and 14-wks. Quality of life (QOL) was measured by the hormone domain of the Expanded Prostate Index Composite (EPIC), at the 0, 7, 14, and 28-wks and patient reported hot flash frequency was assessed weekly. Safety endpoints were serum testosterone and analysis of adverse events. Efficacy endpoints were scores on the EPIC and the number of pa-tient reported hot flashes. RESULTS: 17 patients were enrolled and 15 completed the trial. Of 15 evaluable patients the median age was 68 ± 8.19. Serum analysis demonstrated no change in testosterone at baseline 9.5 ng/ml ± 8.9 vs. end-point 14 ± 8.78 (p = 0.101). No adverse events were reported. Data analysis of the EPIC demonstrated a trend toward improvement after 7 wks and a significant improvement following 14 wks of acupuncture (p = 0.01). Analysis of patient reported frequency showed a significant reduction in the number of hot flashes at 7-wk (6, p = 0.04), 14-wk (2.6, p = 0.001), and 28-wk F/U (3.2, p = 0.01) as compared to baseline 9.57 ± 3.98. CONCLUSIONS: The administration of acupuncture in men with advanced CaP appears to significantly decrease the frequency of hot flashes. No serious ad-verse events were noted and serum testosterone levels were unchanged from baseline suggesting that the mechanism of action of acupuncture for hot flash amelioration is not via increase in testosterone.
基金Supported by grants from Shanghai Municipal Commission of Health and Family Planning:ZY(2018-2020)-ZYJS-03。
文摘Background:Hot flashes are one of the most common symptoms in menopause and significantly affect the quality of life of 67% of menopausal women.Acupuncture is found to be a low risk treatment in treating hot flashes but the evidence for its effectiveness is inconclusive.We developed an optimized acupuncture treatment protocol and designed a randomized controlled trial(RCT) to assess the efficacy of acupuncture for reducing hot flashes in menopausal women.Methods:This is a single-site,single-blind,randomized sham-controlled trial with two parallel arms.A total of 60 eligible patients will be recruited and randomly assigned to either the acupuncture group(n=30) or the sham acupuncture group(n=30).Treatment will be given twice a week,for 30 min,for six consecutive weeks.The primary outcome is the hot flashes scores,assessed using the validated hot flashes diary at baseline,week 3,week 6 and week 10.The secondary outcome will be measured by menopause-specific quality of life(MENQOL) at baseline,week 6,and week 10.Meanwhile,any adverse events will be recorded.Discussion:If the outcome of this study confirms acupuncture to be an effective therapy to reduce hot flashes in menopausal women,we expect this study to inspire further investigations and provide useful information in forming an optimal acupuncture treatment protocol for clinic.Trial registration:Chinese Clinical Trial Registry identifier:ChiCTR1800018638,Date of registration:30 th September 2018.URL:http://www.chictr.org.cn/showproj.aspx?proj=31462.
基金Supported by Guangdong Education Department Youth Innovation Talent Project(Natural Science):2018 KQNCX043Chongqing Science&Health Jointed Project of Technology Innovation and Application Development of Traditional Chinese Medicine:2020 ZY3600+1 种基金Zhang Xijian’s National Famous Chinese Medicine Physician Studio of State Administration of Traditional Chinese MedicineSurface Project of Guangdong Provincial Administration of Traditional Chinese Medicine:20191114。
文摘Objective:To compare the therapeutic effect on menopausal hot flashes between acupuncture and Climen so as to provide a new approach to the treatment of this disease.Methods:A total of 80 cases in line with inclusion criteria were randomized into a treatment group(treated with acupuncture) and a control group(oral administration with climen),40 cases in each one.The treatment for 1 month was as 1 course and lasted consecutively for 2 courses.Before and after treatment,the contents of serum estrogen(estradiol,E_(2)) and 5-hydroxytryptamine(HT) and the scores of the attack frequency and severity scale of hot flashes and sweating,domestic modified Kupperman scale and traditional Chinese medicine(TCM) symptom scale were observed,and the clinical therapeutic effect was evaluated in the two groups separately.Results:Before treatment,there was no difference in the content of E_(2) and 5-HT,the score of hot flashes and sweating,Kupperman score and TCM symptom score in the patients between two groups,indicating the comparability(all P>0.05).Compared with the data before treatment,the contents of serum E_(2)(treatment group vs control group:22.24±11.02 vs 33.12±1.01;22.11±10.19 vs 25.29±2.23) and5-HT(treatment group vs control group:96.12±8.21 vs 131.21±30.21;96.98±7.99 vs 108.29±22.08),the score of hot flashes and sweating(treatment group vs control group:8.24±1.02 vs 3.12±1.01;8.11±1.19 vs 5.29±2.23),Kupperman score(treatment group vs control group:26.12±2.21 vs11.21±0.21;26.98±1.99 vs 18.29±2.08) and TCM symptom score(treatment group vs control group:18.97±3.87 vs 10.12±0.16;19.01±2.29 vs 15.61±2.89) were statistically different after treatment in the two groups(all P<0.05).After treatment,the contents of serum E_(2) and 5-HT,the score of hot flashes and sweating,Kupperman score and TCM symptom score in the treatment group were all different statistically compared with the control group(all P<0.05).There was statistical difference in clinical therapeutic effect in the patients between two group,in which,the therapeutic effect in the treatment group was better than that in the control group(90% vs 77.5%,P<0.05).Conclusion:Acupuncture effectively reduces Kupperman score and TCM symptom score in the patients and its therapeutic effect is better than climen.Regarding relieving hot flashes symptoms in menopausal patients of kidney yin deficiency and improving in attack frequency and severity of hot flashes and sweating,the effects of acupuncture are superior to Climen.Acupuncture obviously increases the contents of serum E_(2) and 5-HT.
文摘By the 3D coupled thermo-mechanical finite element model of linear friction welding of TC4 titanium alloy, the relation between the temperature and the flashes is researched. The numerical simulation results show that the flashes with the wrinkles appear only when the temperature of material in the friction surface is high enough. The flashes, which are made up of material with high temperature, are squeezed out of the component. The appearance of flashes makes the temperature of material in the friction susface slowly increase or even decrease. Compared with the oscillation frequency and the oscillation amplitude, the friction pressure＇ s increase can mare easily attain the flashes with the bigger dimensionz.
基金Acknowledgement This work is supported by the National Natural Science Foundation of China （No. 51204111 ） and the Education Department Foun- dation of Liaoning Province （No. L2012047）.
文摘On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are investigated. The results of numerical simulation show that the temperature of friction surface is higher than that of other region and the peak temperature increases with the increase of welding time. During the process of friction stage, no flash appears because of the low temperature and the small axial friction pressure. At the forging stage, the flashes appear, whose dimensions and bending degree increase with the increase of welding temperature. Moreover, with the increase of rotational velocity and axial forging pressure, the dimensions and the bending degree of flashes of continuous drive friction welding increase.
文摘Purpose: Hormone therapy (estrogen with or without progestin) remains the gold standard treatment for hot flashes in menopausal women, but concerns for the risk of hormone therapy have resulted in its decline and a demand for nonhormonal treatments with demonstrated efficacy for hot flashes. Aim of this study was to examine the efficacy of selective serotonin reuptake inhibitor escitalopram on hot flashes in a healthy sample of non-depressant menopausal women in Japan. Methods: We retrospectively analyzed the medical records of 11 menopausal patients with hot flashes, who received escitalopram (10 mg daily) for 2 weeks between March and August 2012. Hot flashes severities and scores were recorded on a scale of 0 to 10 points, at beginning and end of 2 weeks treatment. Results: At 2 weeks of therapy, 9 of 11 patients reported significant decreases in hot flash frequency and severity, but the remission of the symptom was not observed in 2 patients. Speed of relief from hot flashes was rapid (within one week). Conclusions: Escitalopram 10 mg/day may be a prompt and effective option for treating hot flashes in menopausal women who do not want to use hormone replacement therapy.
文摘This study examined the effects of caffeine, alcohol, and physical activity (PA) on the perceived frequency and severity of hot flashes in menopausal women. Female employees at a Mid-Western university were invited to participate in an on-line survey. The 26-itemized Wo- men’s Health Survey (WHS) included questions regarding demographics, menopausal stage, experience of hot flashes, consumption of caffeinated beverages and alcohol, and participation in PA. One-hundred and ninety-six women completed the study. Ordinary Least Squares regressions revealed PA, caffeine, and alcohol intake were significant in predicting the severity of hot flashes (R2 = 0.068, F(6,180) = 2.195, p = 0.046), though they did not predict frequency of hot flashes (R2 = 0.043, F(6,184) = 1.39, p = 0.221). Participation in aerobic PA increased frequency of hot flashes (p = 0.031);while higher intensity of aerobic PA had an inverse relationship on both frequency and severity of hot flashes (p = 0.011, p = 0.003, respectively). Spearman correlations demonstrated a positive relationship between caffeinated soda intake and frequency (r = 0.17, p = 0.06) and severity (r = 0.19, p = 0.04) of hot flashes. Beverage consumption and PA may predict severity of hot flashes in women. Less frequent, higher intensity aerobic PA may lead to fewer, less severe hot flashes.
文摘Women worldwide are dealing with hot flashes (潮热), a perimenopausal feature that is often tiring,embarrassing, and energeticallydraining. Conventionally, Chinese medicine defines hot flashes as Kidney-yin deficiency and its clinical manifestations include red face,sweating, hot sensations in the palms and soles, mouth and nose dryness, constipation, insomnia, lumbar soreness, knee weakness, redtongue, etc. To obtain a broader perspective and understand the dynamics of hot flashes, we examined the mechanisms behind hot flashesbased on both the knowledge from ancient Chinese medicinal texts, as well as novel research findings of Chinese and Western medicine.This perspective was the foundation for the acupuncture study of our traditional Chinese medicine conducted in 2018-2019 in Shanghai.This study, designed as a pragmatic randomized control trial with two parallel groups, focused on regulating and unblocking conceptionand governor vessels. The results confirmed that our acupuncture method could effectively reduce both the frequency and severity of hotflashes and improve life quality of middle-aged women.
文摘The aim of this study was to evaluate the effectiveness of a pharmaceutical grade isoflavone supplement (Inoclim?) 40 mg per capsule of soy extract rich in daidzin and genistin) on the number of hot flashes and night sweats in menopausal African women. This open, prospective, multicenter study involved 140 menopausal women with climacteric symptoms (i.e., a minimum of five hot flashes and/or moderate to severe night sweats per day). These patients received a daily 40-mg supplement of soy isoflavone contained in an Inoclim? capsule (Laboratoire Innotech International, France). The dose was increased to two capsules per day when there were more than five hot flashes or when the women could not sleep because of night sweats. The patients were followed up over a 4-month period and data were analyzed using EPI-InfoTM version 3.5.1. The outcome measure was fewer hot flashes and night sweats. The mean daily number of episodes of hot flashes was 5.7 at baseline and 1.8 at week 16, corresponding to a decrease of 68.4% (n = 93 patients at baseline and n = 66 at 16 weeks). The mean number of daily episodes of night sweats was 3.7 at baseline and 0.8 at week 16, corresponding to a decrease of 78.4% (n = 127 patients in the first week and n = 73 at 16 weeks). Over 80% of patients took a single one 40 mg capsule per day. The percentage of patients who adhered to the prescription was more than 95% during the 4-month follow-up period. These results confirm the effectiveness of a pharmaceutical grade isoflavone supplement (40 mg, rich in genistin and daidzin) on vasomotor symptoms in menopausal women.
基金supported by National Natural Science Foundation of China (Grant No. 40905001, 40775004)the Main Direction Program of the Knowledge Innovation of Chinese Academy of Sciences (Grant No.KZCX2-YW-206)
文摘The electrical characteristics of thunderstorms in three different altitude regions of the Chinese inland plateau have been analyzed in this paper. The results show, according to the polarity of the surface electric （E） field, that the thunderstorms can be divided into two categories in the study regions： one showing the normal tripole electrical charge structure （normal-type）, and the other showing the special tripole charge structure with a larger-than-usual lower positive charge center （LPCC） at the base of thunderstorm （special-type）, where the induced surface E field is controlled by the LPCC when a thunderstorm is overhead. We find that the two types of thunderstorms have different occurrences in different regions, and the percentage of special-type thunderstorms increases with the altitude. On the whole, the flash rate of thunderstorms is quite low, and the mean value is about 1-3 fl/min, while the flash rate of special-type is slightly greater than that of the normal-type thunderstorm. The statistical results of cloud-to-ground flash （CG） numbers indicate that the ratio of ＋CG flash increases with the altitude, with the value about 14.7 percent through 25.4 percent.
基金the Natural Science Foundation of Anhui Province(No.1408085MD72)the National"863"Program of China(Nos.2014AA06A509,2013AA065502,and 2009AA063005)+2 种基金the Science and Technology Planning Project of Anhui Province(No.1206c0805012)the National Natural Science Foundationof China(No.61378041)the Excellent Youth Foundation of Anhui Scientific Committee(No.1108085J19).
文摘We establish a system to measure the functional absorption cross section of photosystem lI （PSII） （O-PSII） and maximum quantum yield of photochemistry in PSII （Fv/Fm）. The system utilizes a sequence of high-frequency excitation flashes at microsecond intervals to induce a microsecond-level fluorescence yield curve. Parameters o-Psii and Fv/Fm are calculated by fitting the curve using nonlinear regression. Experimental results show that the relative standard deviation （RSD） of the system is less than 3%, and the correlation coefficient of Fv/Fm values measured by this system and those measured by pulse amplitude modulation method is 0.950.
文摘Objective:To conduct a literature review of randomized controlled trials(RCTs)on the use of acupuncture for hot flashes to analyze the characteristics of each study,draw a conclusion on the advantages and disadvantages of previous studies and provide the suggestions for future studies on the same topic.Methods:We searched English and Chinese databases for the literature published from 2009 to 2019 restricted in the English and Chinese language,and we included RCT using acupuncture as the main observational intervention for hot flashes by the criteria.Results:Twenty studies met our eligibility criteria.All the studies were of high quality and confirmed the clinical efficacy of acupuncture for hot flashes,although they used different controlled interventions.The acupuncture treatment and theory of acupoints selection were relatively consistent among the studies,and they had close trial designs.Conclusions:These RCTs on acupuncture were nonuniform,which made the studies on this topic lack coherence,leading to unsatisfactory research outcomes.Therefore,more professional research teams are needed to perform studies on a definite topic and draw a specific conclusion to previous studies before the next step is taken.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC1501500)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grants Nos.2020R004&2021Z003)the Chinese Meridian Project and the International Partnership Program of Chinese Academy of Sciences(Grant No.183311KYSB20200003)。
文摘Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a natural highenergy phenomenon associated with lightning discharges that frequently occur during thunderstorms.However,their production mechanisms and associated processes are still unclear.TGF studies have already been a research spotlight in the atmospheric electricity and high-energy atmosphere research areas.In this paper,we review recent research progresses on TGF studies in the past decade,including TGF detection,the relationship between TGFs and lightning processes,and thunderstorm activities.Several unsolved important scientific questions are discussed.Results suggest that upward TGFs observed by satellite-based detectors are closely connected with the development of in-cloud upward negative leaders.They are usually generated in milliseconds of the initiation of upward negative leaders and may produce a kind of distinct radio emissions because of the generation and propagation of huge amounts of high-energy electrons.By contrast,its counterpart,i.e.,downward TGFs observed by ground-based gamma-ray detectors,is associated with different types of lightning processes,such as downward negative or upward positive leaders,the initial continuing current stage of rocket-triggered lightning flashes return stroke processes.Because of limited observations,how these downward TGFs are generated is still unclear.Benefiting from the development of state-of-the-art instruments with high temporal and spatial resolutions,new insights into the processes and mechanisms of TGFs will be achieved with coordinated observations from satellite-based and ground-based measurements.
基金supported by the National Key Basic Research Program of China(2011CB809100,2013CB531200)the National Natural Science Foundation of China(31221002,31130067,31123004,30900264)
文摘The mitochondria play essential roles in both intracellular calcium and reactive oxygen species signaling.As a newly discovered universal and fundamental mitochondrial phenomenon,superoxide flashes reflect transient bursts of superoxide production in the matrix of single mitochondria.Whether and how the superoxide flash activity is regulated by mitochondrial calcium remain largely unknown.Here we demonstrate that elevating mitochondrial calcium either by the calcium ionophore ionomycin or by increasing the bathing calcium in permeabilized HeLa cells increases superoxide flash incidence,and inhibition of the mitochondrial calcium uniporter activity abolishes the flash response.Quantitatively,the superoxide flash incidence is correlated to the steady-state mitochondrial calcium elevation with 1.7-fold increase per 1.0?F/F0 of Rhod-2 signal.In contrast,large mitochondrial calcium transients(e.g.,peak△F/F0~2.8,duration^2 min)in the absence of steady-state elevations failed to alter the flash activity.These results indicate that physiological levels of sustained,but not transient,mitochondrial calcium elevation acts as a potent regulator of superoxide flashes,but its mechanism of action likely involves a multi-step,slow-onset process.
基金supported by the National Key Basic Research Program of China (Grant No. 2014CB441403)the National Natural Science Foundation of China (Grant No. 41275008)+1 种基金R&D Special Fund for Public Welfare Industry (Grant No. GYHY201306069)Open Project of Key Laboratory of Meteorological Disaster of Ministry of Education (Grant No. KLME1004)
文摘The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate a severe thunderstorm to permit analysis of the conditions that might easily cause +CG flashes. The results showed that strong updrafts play an important role in the occurrence of intracloud flashes. However, frequent +CG flashes require not only strong updrafts but also strong downdrafts in the lower cloud region, conditions that correspond to the later phase of the mature stage and the period of the heaviest solid precipitation of a thunderstorm. During this stage, strong updrafts elevated each charge area in the updraft region to a higher level, which resulted in an inverted tripole charge structure. A wide mid-level region of strong positive charge caused largely by positively charged graupel, presented in the middle of the updraft region because of a non-inductive ice-ice collisional charging mechanism. The charge structure in the downdraft region was consistently more complex and revealed several vertically stacked charge regions, alternating in polarity. Much of the graupel/hail outside the updrafts was lowered to cloud-base by strong downdrafts. In this area, the graupel/hail was charged negatively because of the transportation of negatively charged graupel/hail from higher regions of negative charge in the updrafts, and via the inductive charging mechanism of collisions between graupel/hail and cloud droplets at the bottom of the cloud. Consequently, a large region of negative charge formed near the ground. This meant that +CG flashes were initiated more easily in the lower inverted dipole, i.e., the middle region of positive charge and lower region of negative charge. Frequent +CG flashes began almost synchronously with dramatic increases in the storm updrafts, hail volume, and total flash rate. Therefore, the occurrence of +CG flashes appears a good indicator of storm intensification and it could have some use as a predictor of severe weather in the form of hail.
基金Financial supports from the Swiss National Science Foundation(Project No.200021_147058)the European Union's Horizon 2020 research and innovation programme(grant agreement.no 737033-LLR)are acknowledged.It is also supported by the China Scholarship Council(CSC).
文摘The authors present an analysis of different charge transfer modes during upward negative flashes.The analysis includes a total number of 94 pulses that occurred during two upward negative flashes recorded at the Säntis Tower.The pulses included 59 mixed-mode(MM)initial continuous current(ICC)pulses,17 M-component-type ICC(M-ICC)pulses,8 returnstroke pulses,and 10 classical M-component(MC)pulses.It is found that the initial stage of the flash is responsible for the largest share of the total charge transferred to the ground.Simulation results for the electric fields associated with the considered charge transfer modes are presented and discussed.Return stroke(RS)and MM pulses were simulated adopting the MTLE model,while MCs and M-ICC pulses were simulated using the guided wave model of Rakov et al.The simulated results are shown to be in good agreement with simultaneous records of electric fields measured at a distance of 15 km from the Säntis Tower.The inferred velocities for MCs and M-ICC pulses range from 2.0×10^(7) to 9.0×10^(7) m/s,and the corresponding junction point heights range from 1.0 to 2.0 km.The inferred pulse velocities for RSs and MM pulses range from 1.3×10^(8) to 1.65×10^(8) m/s.The inferred current attenuation constants of the MTLE model obtained in this study range from 0.3 to 0.8 km,lower than the value of 2 km previously suggested for RSs in downward flashes.The obtained results support the assumption that the mode of charge transfer to the ground giving rise to MM pulses is similar to that of RSs.The results are also in support of the generally assumed similarity between M-ICC pulses and classical MCs.
