Numbers Of Flashes Research Articles

Acupuncture for hot flashes in hormone receptor-positive breast cancer, a pooled analysis of individual patient data from parallel randomized trials.

12124 Background: Hot flashes are a common side effect of endocrine therapy in breast cancer patients (pts). In a coordinated multinational study, we evaluated the impact of acupuncture on hot flashes and related symptoms in hormone receptor-positive breast cancer pts undergoing adjuvant endocrine therapy in the USA, China, and South Korea. Methods: Parallel randomized trials were conducted at three sites: Dana-Farber Cancer Institute, USA; Jiangsu Hospital of Traditional Chinese Medicine, China; and Daegu Catholic University Medical Center, Republic of Korea, using the same inclusion/exclusion criteria, randomization, and measures. Breast cancer pts receiving adjuvant endocrine therapy and having ≥14 hot flashes per week were randomized equally to acupuncture (A) or usual care (UC); randomization was stratified by number of hot flashes per day (2-6 or 7+). Pts in arm A received a standardized acupuncture protocol twice per week for 10 weeks; pts in the UC arm received usual care. Symptoms were assessed at baseline and week 10. The primary endpoint was change in the Endocrine Symptom Subscale (ESS) of the Functional Assessment of Cancer Therapy-Endocrine Systems (FACT-ES). Secondary endpoints included changes in the FACT-Breast (FACT-B) and Daily Hot Flash Score (DHFS), a measure incorporating hot flash frequency and severity. Target enrollment was 160 pts (USA 80, China 40, Korea 40) providing 84% power to detect a clinically meaningful change in the ESS. Analyses were intention-to-treat. A pooled analysis of individual patient data was performed using linear models adjusted for site and baseline number of hot flashes. Results: Between Jan. 2019 and June 2021, 158 female pts with stage 0-III breast cancer were randomized from the USA (n=78), China (n=40), and South Korea (n=40). Median age was 48 years (range: 25 to 73). At baseline, pts reported similar numbers of hot flashes between study arms (6.2± 4.3 vs. 6.5± 3.8 per day). At week 10, pts in arm A reported statistically significant improvements in ESS score, FACT-B total score and DHFS compared with the UC arm (Table). The reduction in the DHFS from baseline in arm A was 53%. There were no serious adverse events. Conclusions: Acupuncture led to statistically and clinically meaningful improvements in hot flashes, endocrine symptoms, and breast cancer-specific quality of life in women undergoing adjuvant hormonal therapy for breast cancer in the USA, China and South Korea. Clinical trial information: NCT00797732, ChiCTR2100045888, KCT0003618. [Table: see text]

The Development of Audio-Visual Integration for Temporal Judgements.

Adults combine information from different sensory modalities to estimate object properties such as size or location. This process is optimal in that (i) sensory information is weighted according to relative reliability: more reliable estimates have more influence on the combined estimate and (ii) the combined estimate is more reliable than the component uni-modal estimates. Previous studies suggest that optimal sensory integration does not emerge until around 10 years of age. Younger children rely on a single modality or combine information using inappropriate sensory weights. Children aged 4–11 and adults completed a simple audio-visual task in which they reported either the number of beeps or the number of flashes in uni-modal and bi-modal conditions. In bi-modal trials, beeps and flashes differed in number by 0, 1 or 2. Mutual interactions between the sensory signals were evident at all ages: the reported number of flashes was influenced by the number of simultaneously presented beeps and vice versa. Furthermore, for all ages, the relative strength of these interactions was predicted by the relative reliabilities of the two modalities, in other words, all observers weighted the signals appropriately. The degree of cross-modal interaction decreased with age: the youngest observers could not ignore the task-irrelevant modality—they fully combined vision and audition such that they perceived equal numbers of flashes and beeps for bi-modal stimuli. Older observers showed much smaller effects of the task-irrelevant modality. Do these interactions reflect optimal integration? Full or partial cross-modal integration predicts improved reliability in bi-modal conditions. In contrast, switching between modalities reduces reliability. Model comparison suggests that older observers employed partial integration, whereas younger observers (up to around 8 years) did not integrate, but followed a sub-optimal switching strategy, responding according to either visual or auditory information on each trial.

Sources of noise during accumulation of evidence in unrestrained and voluntarily head-restrained rats.

Decision-making behavior is often characterized by substantial variability, but its source remains unclear. We developed a visual accumulation of evidence task designed to quantify sources of noise and to be performed during voluntary head restraint, enabling cellular resolution imaging in future studies. Rats accumulated discrete numbers of flashes presented to the left and right visual hemifields and indicated the side that had the greater number of flashes. Using a signal-detection theory-based model, we found that the standard deviation in their internal estimate of flash number scaled linearly with the number of flashes. This indicates a major source of noise that, surprisingly, is not consistent with the widely used 'drift-diffusion modeling' (DDM) approach but is instead closely related to proposed models of numerical cognition and counting. We speculate that this form of noise could be important in accumulation of evidence tasks generally.

Fusion and fission in the visual pathways.

Inconsistent information from different modalities can be delusive for perception. This phenomenon can be observed with simultaneously presented inconsistent numbers of brief flashes and short tones. The conflict of bimodal information is reflected in double flash or fission, and flash fusion illusions, respectively. The temporal resolution of the vision system plays a fundamental role in the development of these illusions. As the parallel, dorsal and ventral pathways have different temporal resolution we presume that these pathways play different roles in the illusions. We used pathway-optimized stimuli to induce the illusions on separately driven visual streams. Our results show that both pathways support the double flash illusion, while the presence of the fusion illusion depends on the activated pathway. The dorsal pathway, which has better temporal resolution, does not support fusion, while the ventral pathway which has worse temporal resolution shows fusion strongly.

Motion artifacts on 240-Hz OLED stereoscopic 3D displays

Temporal multiplexing is a popular approach for presenting different images to the two eyes in stereoscopic 3D (S3D) displays. We examined the visibility of flicker and motion artifacts—judder, motion blur, and edge banding—on a 240-Hz temporally multiplexed S3D OLED display. Traditionally, a frame rate of 120 Hz (60 Hz per eye) is used to avoid visible flicker, but there is evidence that higher frame rates provide visible benefits. In a series of psychophysical experiments, we measured the visibility of artifacts on the OLED display using temporal multiplexing and those of a 60-Hz S3D LCD using spatial multiplexing. We determined the relative contributions of the frame rate of the content, update rate of the display, duty cycle, and number of flashes. We found that short duty cycles and low flash numbers reduce the visibility of motion artifacts, while long duty cycles and high flash numbers reduce flicker visibility.

55.1: Distinguished Paper: Motion Artifacts on 240Hz OLED Stereoscopic 3D Displays

AbstractWe examined the visibility of motion artifacts—judder, motion blur, and edge banding—on a Samsung 240Hz stereoscopic 3D (S3D) OLED display. We determined the relative contributions of the frame rate of the content, update rate of the panel, duty cycle, and flash number. We compared the visibility of artifacts on the Samsung display with those on a 60Hz S3D LCD. Short duty cycles and low flash numbers reduce the visibility of motion artifacts.

Phenomenology of the sound-induced flash illusion

Past studies, using pairings of auditory tones and visual flashes, which were static and coincident in space but variable in time, demonstrated errors in judging the temporal patterning of the visual flashes-the sound-induced flash illusion. These errors took one of the two forms: under-reporting (sound-induced fusion) or over-reporting (sound-induced fission) of the flash numbers. Our study had three objectives: to examine the robustness of both illusions and to consider the effects of stimulus set and response bias. To this end, we used an extended range of fixed spatial location flash-tone pairings, examined stimuli that were variable in space and time and measured confidence in judging flash numbers. Our results indicated that the sound-induced flash illusion is a robust percept, a finding underpinned by the confidence measures. Sound-induced fusion was found to be more robust than sound-induced fission and a most likely outcome when high numbers of flashes were incorporated within an incongruent flash-tone pairing. Conversely, sound-induced fission was the most likely outcome for the flash-tone pairing which contained two flashes. Fission was also shown to be strongly driven by stimuli confounds such as categorical boundary conditions (e.g. flash-tone pairings with ≤2 flashes) and compressed response options. These findings suggest whilst both fission and fusion are associated with 'auditory driving', the differences in the occurrence and strength of the two illusions not only reflect the separate neuronal mechanisms underlying audio and visual signal processing, but also the test conditions that have been used to investigate the sound-induced flash illusion.

Paullinia cupana para o controle de fogachos em pacientes com câncer de mama: um estudo piloto

ABSTRACTObjective:To evaluated whether Paullinia cupana decrease number and severity of hot flashes in breast cancer survivors.Methods:This was a prospective phase II pilot study. We studied female breast cancer survivors who had completed the cancer treatment 3 months previously and who were experiencing at least 14 hot flashes per week. At least 9 of the 15 patients were required to have a decrease of at least 50% in hot flash severity score in keeping with the Simon Design. Patients received 50mg of dry extract of Paullinia cupana orally twice a day for 6 weeks. We assessed both frequency and severity of hot flashes.Results:A total of 18 patients started the Paullinia cupana treatment, and 15 completed the study. Three patients left the study immediately after starting the treatment because of personal difficulties in participation or noncompliance. Of the 15 patients who completed the study 10 had a decrease of more than 50% in hot flash severity scores. During the 6 weeks of treatment, statistically significant decreases were seen in both numbers of hot flashes (p=0.0009) and severity scores (p<0.0001). Paullinia cupana was well tolerated, and there were no instances of discontinuation because of toxicity.Conclusions: Paullinia cupana appears promising for controlling hot flashes. More extensive studies seem warranted.

Optimization of Transmission-Line Route Based on Lightning Incidence Reported by the Lightning Location System

Optimal route selection of a transmission line is significantly beneficial to reduce its lightning trip-out rate. This paper proposes a method, considering the minimal annual flash number to transmission lines, to select the optimal route from the initial point to the destination based on the lightning location system. First, the ground flash density and distribution of lightning peak current maps are drawn via the improved grid method. The flash grid and flash node are proposed based on these maps. The objective function is expressed as the summation of the grid distance of the flash node, and solved via the Dijkstra algorithm. The conditional minimum transit cost is also provided to find the optimal corridor. Five 500-kV transmission lines are used to validate the effectiveness of the proposed method. The results indicate that the annual expected flash numbers of all lines are markedly reduced.

Effect of bacterial ice nuclei on the frequency and intensity of lightning activity inferred by the BRAMS model

Abstract. Many studies from the last decades have shown that airborne microorganisms can be intrinsically linked to atmospheric processes. Certain bacteria may constitute the most active ice nuclei found in the atmosphere and might have some influence on the formation of ice crystals in clouds. This study deals with the ice nucleation activity of Pseudomonas syringae inside of thunderstorms through numerical simulations using BRAMS (Brazilian Regional Atmospheric Model System). The numerical simulations were developed in order to investigate the effect on the total amount of rainwater as a function of ice nuclei (IN) P. syringae concentrations with different scenarios (classified as S2 to S4 scenarios) corresponding to a maximum of 102 to 104 IN bacteria per liter of cloud water plus the BRAMS default (classified as S5 scenario). Additionally, two other scenarios were included without any IN (S1) and the sum of RAMS default and S4 scenario (classified as S6). The chosen radiosonde data is for 3 March 2003, typical summertime in São Paulo City which presents a strong convective cell. The objective of the simulations was to analyze the effect of the IN concentrations on the BRAMS modeled cloud properties and precipitation. The simulated electrification of the cloud permitted analysis of the total flashes estimated from precipitable and non-precipitable ice mass fluxes in two different lightning frequencies. Among all scenarios, only S4 and S6 presented a tendency to decrease the total cloud water, and all bacteria scenarios presented a tendency to decrease the total amount of rain (−8%), corroborating other reports in the literature. All bacteria scenarios also present higher precipitable ice concentrations compared to S5 scenario, the RAMS default. The main results present the total flash number per simulation as well. From the results, the total flash numbers, from both lightning frequencies, in S4 and S6 scenarios, are from 3.1 to 3.7 higher than the BRAMS default. Even the lower bacterial concentrations (scenarios S2 and S3) produced 3 time higher number of flashes, compared to S5 scenario. This result is a function of the hydrometeors in each simulation. In conclusion, IN bacteria could affect directly the thunderstorm structure and lightning formation with many other microphysical implications.

Effects of licorice root extract on the number of nocturnal hot flashes in menopausal women

Background and aimMenopause entails many complications on women’s quality of life. Hot flashes is the most common and bothersome effect, mainly treated with hormonal therapy. However, because of its side effects, there is controversy over its administration. Thus, therapies with fewer complications such as herbs warrant investigation. The aim of this randomized double-blind clinical trial was to determine the effects of licorice root extract on the number of nocturnal hot flashes in menopausal women referring to healthcare centers affiliated to Shahid Beheshti University of Medical Sciences in 2008. Materials and methods68 women were selected with purposive sampling method and randomly divided into 2 equal experimental and placebo groups. After taking their consent, data were gathered with a questionnaire and information forms validated through content method. Reliability was ensured by using standard brands for meter band, weights, stethoscope and sphygmomanometer calibrated according to guidelines of manufacturers. Both experimental and placebo groups took capsules containing 330 mg licorice and starch 3 times a day (morning, noon and night) over 4 weeks respectively. The numbers of nocturnal hot flashes were measured from 2 weeks before the intervention to the end of it. Data were analyzed by SPSS 11.5. FindingsMeans of age, duration of amenorrhea and duration of hot flashes were 53.13, 1.65 and 1.65 respectively. The numbers of hot flashes in the experimental group were 4.82 before the intervention and 1.05 after it with a significant difference. However, no significant difference was found before and after the intervention in the placebo group. ConclusionLicorice as an herb may decrease the number of nocturnal hot flashes in menopausal women, increasing their physical and psychological health. Keywords: Hot flashes, Menopause, Licorice. *Corresponding Author: Fatemeh Nahidi. Lecturer, Dept. of Midwifery, Faculty of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran. E-mail: nahidifateme@yahoo.com

Variations in the microstructure and electrical resistance of the SWCNT films under consecutive photoflash exposures

A film of unpurified single-walled carbon nanotubes (SWCNTs) synthesized by the floating catalyst method using ferrocene as the catalyst precursor was subjected to different numbers of flashes and the products were studied. In addition to the remaining SWCNTs, Fe2SiO4 particles covered with amorphous carbon were found to attach on the SWCNTs, and the size increased with flash numbers. Fe2SiO4 arose from the oxidation of Fe3C, a ferrocene-induced catalyst particle embedded in the SWCNTs, where Si provided by SiO2 released from the mullite tube at 1200°C during SWCNT growth. The amorphous carbon coating was attributed to insufficient time of the precipitated carbon to crystallize during rapid cooling after the flash. Variation of the Raman ID/IG ratio from an initial value of 0.035 to 0.025 after 100 flashes was due to competition between the removal of carbon from the nanotubes and the formation of amorphous carbon on the Fe2SiO4 particle surface. The electrical resistance of the SWCNT film increased with the number of flashes but the change became progressively smaller, with the increment decreasing from 17.5% to 0.2%. Similar experiments using purified SWCNTs were performed, and no such particles were observed.

Pregabalin for hot flashes in women: NCCTG trial N07C1

9513 Background: Hot flashes are a major problem in many women for which better treatment options are needed. Given the known efficacy of gabapentin for decreasing hot flashes, it was decided to evaluate pregabalin, with hopes that it would work better and/or with fewer toxicities. Methods: A three-arm, double-blinded, placebo-controlled randomized trial was developed. Women with bothersome hot flashes (at least 28/week) were randomized to receive either a placebo or target pregabalin oral doses of 75 mg bid or 150 mg bid (starting at 50 mg/d and then increasing the dose at weekly intervals to 50 mg bid, then 75 mg bid, and then, in the higher dose arm, 150 mg bid); patients were treated for 6 weeks. Hot flash numbers and scores (hot flash number times mean severity) were measured using a validated daily hot flash diary. A one-week baseline period preceded initiation of study tablets. The primary endpoint was the average intra-patient difference in hot flash score between baseline and week six, comparing the higher dose pregabalin arm and the placebo arm. With the planned sample size of 55 patients per arm, there was an 80% power and two-sided 5% Type I error rate to detect a difference of 0.54 standard deviations, or 1.08 hot flashes per day, or 2.7 units of hot flash score per day. Results: 207 patients were randomized between 6/20/2008 and 8/21/2008. The study arms were well balanced. Mean/median daily hot flash scores and frequencies for all pts at baseline were 15.7/13.4 and 8.3/7.7, respectively. The table shows the decreases in hot flashes from the baseline to the sixth treatment week. Larger numbers illustrate greater hot flash reductions. Toxicity information, quality of life information, and information regarding the effects of hot flashes on subjective symptoms will be available at the meeting time. Conclusions: Pregabalin reduces hot flashes in women. There appears to be similar effects with both studied doses. [Table: see text] No significant financial relationships to disclose.

Saharan dust, lightning and tropical cyclones in the eastern tropical Atlantic during NAMMA‐06

During the summer of 2006, the downstream component of African Monsoon Multidisciplinary Analyses Campaign (NASA‐AMMA (NAMMA)) examined African Easterly Waves (AEWs) emerging from the coast of Africa. Six of these disturbances went on to become named systems in the Tropical Atlantic. Two of the six systems (Tropical storm Debby and Hurricane Helene) developed in the extreme eastern Atlantic and were associated with dust outbreaks, elevated ice contents and frequent lightning. Here we show that in the early tropical cyclo‐genesis stages of these systems there were thousands of cloud‐to‐ground (CG) lightning flashes as measured by a ground‐lightning network. TRMM overpasses show high precipitation ice content above the freezing level and high latent heat release. Super‐cooled water can be inferred in the lower parts of cloud systems in concert with observed high ice concentrations at high altitudes creating charge separation based on the large numbers of CG flashes.

Phase III double-blinded, randomized trial to evaluate the use of black cohosh in the treatment of hot flashes: A North Central Cancer Treatment Group study

8013 Background: Hot flashes can cause significant morbidity in post-menopausal women and women undergoing or finished with breast cancer treatment. Based on initial pilot data suggesting black cohosh could be efficacious in the treatment of hot flashes, a phase III trial was initiated. Methods: A double-blind, randomized, cross-over methodology with two 4 week periods, was used to study the efficacy of black cohosh (1 capsule, Cimicifuga racemosa 20 mg BID) for the treatment of hot flashes in women. Participants kept a daily hot flash diary during a baseline week and then during an 8-week cross-over treatment period. Treatment effectiveness was measured using the mean daily numbers of hot flashes and the hot flash scores; the latter measured by assigning points (1–4, for mild to very severe) to each hot flash based on severity and then adding the points for a given time period. The study design provided 80% power to detect a moderate effect size difference (1/2 standard deviation) in the hot flash scores between the two treatment groups. Results: 132 patients were randomized between 10/31/03 - 3/4/04. Data on 80% of patients have been analyzed and are reported here. Toxicity was minimal and not different by treatment group with 83% of patients receiving black cohosh and 76% of patients receiving placebo reporting no adverse events. Patients receiving black cohosh reported a mean decrease in hot flash score (comparing the fourth treatment week to the baseline week) of 20% compared to 27% for patients on placebo (p=0.53). Mean hot flash frequency was reduced 17% on black cohosh and 26% on placebo (p=0.36). Patient treatment preferences were measured after completion of both treatment periods by ascertaining which treatment period, if any, the patient’s preferred: 34% of patients preferred the black cohosh treatment, 38% preferred placebo, and 28% did not prefer either treatment. Conclusion: This trial failed to provide any evidence that black cohosh reduced hot flashes more than the placebo did. No significant financial relationships to disclose.

Winter Lightning and Heavy Frozen Precipitation in the Southeast United States

This study addresses winter season lightning by examining synoptic-scale circulations, cloud-to-ground (CG) lightning patterns, and frozen precipitation. Specifically, locations, frequencies, and polarities of CG flashes are related to the location, intensity, and type of heavy frozen precipitation (snow, freezing rain, or ice pellets) for seven winter storms affecting the southeast United States from 1994 through 1997. The results suggest two distinct phases of winter storm development, each producing different patterns of CG lightning and frozen precipitation. These phases are termed the arctic front (AF) and migratory cyclone (MC) types. Analysis was performed on 27 periods within the seven cases. In several periods, there were significant numbers of CG flashes within or near a subfreezing surface air mass and frozen precipitation when a quasistationary arctic front existed. These periods were classified as AF phases. This flash pattern indicates a connection between the intensity of convection (associated with CG flashes) and downwind frozen precipitation. In these situations there was strong southwesterly flow aloft, which may have advected ice particles from these convective clouds into stratiform clouds near the frontal surface. This process resembles the ‘‘seeder‐feeder’’ mechanism of precipitation growth. The AF phases eventually developed into MC phases, and the latter were more common in this study. The MC phases in general exhibit a different spatial relationship between CG lightning and heavy frozen precipitation; that is, CG flashes retreat toward the warm sector of the cyclone and thus are not proximal to the 0 8C surface isotherm. There appears to be little connection between convection and frozen precipitation in most of these situations. The distinction between AF and MC phases, in conjunction with CG lightning monitoring, may aid forecasts of the duration and amount of frozen precipitation during winter storms.

Contribution to the climatological study of lightning

In this work, a new parameterization of the thunderstorm cloud electrical flash frequency is obtained on the basis of simple dimensional arguments. The flash frequency is expressed as a power function of both the cloud top height and the cloud droplet concentration, thus partly taking into account the role of the microphysical cloud characteristics. Since droplet concentrations are not predicted by General Circulation Models (GCMs) and further show great variability, two different “standard” droplet concentrations, respectively valid for continental and maritime thunderstorms, are used. A numerical experiment has been made by using the METEO‐France GCM “ARPEGE” in relation to both, this new parameterization and the Price and Rind (1992) parameterization, in order to determine the global characteristics of electrical flashes. The analysis of the results reveals that the mean annual global flash frequency as well as the total number of flashes that strike annually the globe are higher when the new parameterization is used but are in better agreement with the Optical Transient Detector (OTD) (Christian et al., 1996) observations, thus indirectly attesting for its validity. Further, the good agreement between monthly and diurnal global flash numbers and the corresponding OTD observations confirms the ability of “ARPEGE” of correctly representing the global thunderstorm development. Finally, the new parameterization has been used in a second numerical experiment in order to infer the role of a doubling of CO2 on the global distribution of electrical flashes. A 10% increase of the mean global annual flash frequency is obtained for a surface warming of roughly 2°C.

Tools for flash-photolysis experiments on voltage-clamped muscle fibre segments.

An experimental set-up is described that allows the combination of rapid transmembrane voltage changes and photometric calcium recording with the fast photochemical turnover of substances applied externally or intracellularly to cut skeletal muscle fibres. It consists of a double-vaseline-gap system, designed for use with a xenon-flash-lamp device and a dual-wavelength microscope photometer. The pools of the vaseline gap chamber that contain the solutions surrounding the cut ends and the voltage-clamped segment of the muscle fibre are closed and have volumes of 20-50 microl. Thin tubes allow rapid solution change or continuous perfusion in the chamber compartments. Accessory tools were constructed to simplify focussing and measuring the flash-light intensity. A pilot light delivered from a red laser diode is used as a guide beam to target the ultraviolet (UV) flash to the preparation. The light distribution in the focal region and the relative changes in flash intensity with increasing numbers of flashes were quantified with an instrument that integrates the photo-current of a UV-sensitive silicon diode. The function of the set-up was demonstrated by measuring the efficiency of Ca2+ release from DM-nitrophen in quartz capillaries using the Ca(2+)-sensitive dye antipyrylazo III and by recording the flash-induced recovery of L-type calcium currents in muscle fibres blocked by the light-sensitive dihydropyridine drug nifedipine.

16 The role of amino acid residues in the S2 and S3 strands in the B β-sheet for the PAI-1 stability

In the glow curves of chloroplasts excited by a series of flashes at +1°C the intensity of the main thermoluminescence band appearing at +30°C (B band; B, secondary acceptor of Photosystem II) exhibits a period-4 oscillation with maxima on the 2nd and 6th flashes indicating the participation of the S3 state of the water-splitting system in the radiative charge recombination reaction. After long-term dark adaptation of chloroplasts (6 h), when the major part of the secondary acceptor pool (B pool) is oxidized, a period-2 contribution with maxima occurring at uneven flash numbers appears in the oscillation pattern. The B band can even be excited at −160°C as well as by a single flash in which case the water-splitting system undergoes only one transition (S1 → S2). The experimental observations and computer simulation of the oscillatory patterns suggest that the B band originates from charge recombination of the S2B− and S3B− redox states. The half-time of charge recombination responsible for the B band is 48 s. When a major part of the plastoquinone pool is reduced due to prolonged excitation of the chloroplasts by continuous light, a second band (Q band; Q, primary acceptor of Photosystem II) appears in the glow curve at +10°C which overlaps with the B band. In chloroplasts excited by flashes prior to DCMU addition only the Q band can be observed showing maxima in the oscillation pattern at flash numbers 2, 6 and 10. The Q band can also be induced by flashes after DCMU addition which allows only one transition of the water-splitting system (S1 → S2). In the presence of DCMU, electrons accumulate on the primary acceptor Q, thus the Q band can be ascribed to the charge recombination of either the S2Q− or S3Q− states depending on whether the water-splitting system is in the S2 or the S3 state. The half-time of the back reaction of Q− with the donor side of PS II (S2 or S3 states) is 3 s. It was also observed that in a sequence of flashes the peak positions of the Q and B bands do not depend on the advancement of the water-splitting system from the S2 state to the S3 state. This result implies that the midpoint potential of the water-splitting system remains unmodified during the S2 → S3 transition.

Positive cloud‐to‐ground lightning discharges in Kathmandu thunderstorms

The occurrence of positive cloud‐to‐ground lightning discharges in thunderstorms in the vicinity of Kathmandu, Nepal (27.4°N, 85.2°E) has been recorded during the 21‐month period from March 1987 to November 1988 inclusive, using the daily registrations of a CGR3 lightning flash counter that provided records of the approximate numbers of positive ground flashes, negative ground flashes, and cloud flashes, with effective ranges of about 12 km for cloud flashes, 14 km for negative ground flashes, and 16 km for positive ground flashes. The detection of positive ground flashes was based on the presence of a relatively large negative‐going step in the electric field change caused by the positive return stroke in the discharge. It was found that the overall mean proportion of positive ground flashes to all ground flashes was 0.28, and that the overall mean positive ground flash density was 0.6 km−2 yr−1. The uncertainty in these values is about ±50%. The proportions of positive ground flashes in three of the climatic periods in the year were 0.26 in the premonsoon period (February to May inclusive), 0.34 in the monsoon period (June to August inclusive), and 0.38 in the postmonsoon period (September to November inclusive). This apparent increase in the proportion is accompanied by a seasonal decline in electrical activity, the premonsoon period being the most active, and the postmonsoon the least active. The increase also appears to be associated with a decrease in the proportion of cloud flashes to total flashes. The proportion of positive ground flashes is larger than is observed in most low‐altitude tropical and subtropical sites but is smaller than that observed in winter thunderstorms at some higher‐latitude sites. Possible reasons for the relatively high rate of occurrence of positive ground flashes (unsupported by concurrent atmospheric soundings) are the site altitude, thundercloud charge heights, vertical wind shear and the mountainous nature of the terrain.