Flickering gamma-ray flashes, the missing link between gamma glows and TGFs.

Two different hard-radiation phenomena are known to originate from thunderclouds: terrestrial gamma-ray flashes (TGFs) and gamma-ray glows. Both involve an avalanche of electrons accelerated to relativistic energies but are otherwise different. Glows are known to last for one to hundreds of seconds, have moderate intensities and originate from quasi-stationary thundercloud fields.

Highly dynamic gamma-ray emissions are common in tropical thunderclouds.

Thunderstorms emit fluxes of gamma rays known as gamma-ray glows, sporadically observed by aircraft, balloons and from the ground. Observations report increased gamma-ray emissions by tens of percent up to two orders of magnitude above the background, sometimes abruptly terminated by lightning discharges. Glows are produced by the acceleration of energetic electrons in high-electric-field regions within thunderclouds and contribute to charge dissipation.

Secondary Fast Breakdown in Narrow Bipolar Events.

The physical mechanism of Narrow bipolar events (NBEs) has been studied for decades but it still holds many mysteries. Recent observations indicate that the fast breakdown discharges that produce NBEs sometimes contain a secondary fast breakdown that propagates back in the opposite direction but this has not been fully addressed so far in electromagnetic models. In this study, we investigate fast breakdown using different approaches that employ a Modified Transmission Line with Exponential decay (MTLE) model and propose a new model, named "rebounding MTLE model," which reproduces the secondary fast breakdown current in NBEs.

Timing Calibration and Windowing Technique Comparison for Lightning Mapping Arrays.

Since their introduction 22 years ago, lightning mapping arrays (LMA) have played a central role in the investigation of lightning physics. Even in recent years with the proliferation of digital interferometers and the introduction of the LOw Frequency ARray (LOFAR) radio telescope, LMAs still play an important role in lightning science. LMA networks use a simple windowing technique that records the highest pulse in either 80 μs or 10 μs fixed windows in order to apply a time-of-arrival location technique.

Determining Electric Fields in Thunderclouds With the Radiotelescope LOFAR.

An analysis is presented of electric fields in thunderclouds using a recently proposed method based on measuring radio emission from extensive air shower events during thunderstorm conditions. This method can be regarded as a tomography of thunderclouds using cosmic rays as probes. The data cover the period from December 2011 till August 2014.

Fast negative breakdown in thunderstorms.

Thunderstorms are natural laboratories for studying electrical discharges in air, where the vast temporal, spatial, and energy scales available can spawn surprising phenomena that reveal deficiencies in our understanding of dielectric breakdown. Recent discoveries, such as sprites, jets, terrestrial gamma ray flashes, and fast positive breakdown, highlight the diversity of complex phenomena that thunderstorms can produce, and point to the possibility for electrical breakdown/discharge mechanisms beyond dielectric breakdown theory based mainly on laboratory experiments. Here we present one such confounding discovery, termed fast negative breakdown, that does not fit with our current understanding of dielectric breakdown.

Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms.

A long-standing but fundamental question in lightning studies concerns how lightning is initiated inside storms, given the absence of physical conductors. The issue has revolved around the question of whether the discharges are initiated solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations of a relatively unknown type of discharge, called fast positive breakdown, that is the cause of high-power discharges known as narrow bipolar events.

Electrical activity during the 2006 Mount St. Augustine volcanic eruptions.

By using a combination of radio frequency time-of-arrival and interferometer measurements, we observed a sequence of lightning and electrical activity during one of Mount St. Augustine's eruptions. The observations indicate that the electrical activity had two modes or phases.

Controlled studies of the efficacy and safety of combined probucol-colestipol therapy.

A comprehensive clinical evaluation of the effects of combined probucol-colestipol therapy was undertaken in 71 hypercholesterolemic patients. In the first 18-month double-blind, double-placebo, crossover study, the effects of 1 g/day of probucol and 20 g/day of colestipol were compared with the drugs used singly in 47 patients. The combination decreased low density lipoprotein (LDL) cholesterol from a diet-placebo baseline of 242 +/- 51 mg/dl to 171 +/- 41 mg/dl.

Platelet function in hypercholesterolemics before and after hypolipidemic drug therapy.

Platelet function parameters were studied in type II hyperlipoproteinemics in relation to baseline and drug-induced changes in serum cholesterol levels. There were no significant differences between 28 type II hyperlipoproteinemics and 19 normal subjects in baseline values for platelet aggregation, thromboxane generation, sensitivity to prostacyclin, plasma platelet factor 4 or beta-thromboglobulin. Eleven of the hyperlipoproteinemic patients were treated with a combination of the cholesterol-lowering drugs probucol and colestipol.

Serum lipids in normo- and hyperlipidemics after methyldopa and propranolol.

We report on serum lipoprotein changes after antihypertensive therapy in nine subjects with type II hyperlipoproteinemia and eight subjects with normolipidemia. They received placebo for 6 wk, followed by random order crossover between methyldopa and propranolol for 6 mo. Physical activity, diet, and other drugs were monitored for constancy.

Low-dose colestipol plus probucol for hypercholesterolemia.

The hypocholesterolemic and adverse effects of colestipol, 20 g/day, and colestipol, 10 g/day combined with probucol, 1 g/day, were compared. A double-placebo, diet-controlled, crossover trial that lasted 19 months was undertaken on 22 hypercholesterolemic patients who had low-density lipoprotein (LDL) cholesterol levels greater than 180 mg/dl after 3 months of diet and placebo treatment. Uniformity of diet and physical activity were monitored throughout the study.

Probucol with colestipol in the treatment of hypercholesterolemia.

The effects of therapy with 1 g of probucol and 20 g of colestipol were compared with those of the drugs used singly on 47 patients with hypercholesterolemia in a double-blind, double-placebo, diet-controlled, crossover trial that lasted 18 months. The probucol and colestipol combination, but neither drug alone, reduced mean serum low-density-lipoprotein (LDL)-cholesterol levels from 242 +/- 51 (SE) mg/dL during the diet and placebo phase to 171 +/- 41 mg/dL. Probucol significantly lowered high-density-lipoprotein (HDL)-cholesterol levels and increased LDL:HDL-cholesterol ratios.

Electrocardiographic effects of probucol. A controlled prospective clinical trial.

Probucol is known to prolong QT intervals in some patients and to produce fatal arrhythmias in selected animal species. To assess the prevalence and clinical relevance of this effect in a controlled manner, we analyzed electrocardiograms (ECGs) and medical events in patients during a placebo-controlled crossover trial comparing single or combined administration of probucol and colestipol. Forty-two Type II hyperlipoproteinemic patients were studied for eighteen to twenty-four months.

The effect of variable fat diets and cholesterol-lowering drugs on Antithrombin III levels in hyperlipoproteinemic and normal subjects.

Functional and immunological Antithrombin III (AT III) levels were studied in normal and hyperlipoproteinemic subjects undergoing crossover therapeutic trials of either diets or hypocholesterolemic drugs. The diet trial subjects, 7 hyperlipoproteinemics and 15 normals, were randomly assigned to crossover between a high saturated fat diet (P/S ratio 1:8) and a high polyunsaturated fat diet (P/S ratio 4:1) for periods of 6-8 weeks, preceded by a baseline period on regular American diet (P/S ratio 1:1). For the drug trials, 33 type II A or B hyperlipoproteinemics were treated in random and double-blind fashion with Colestipol (20 gm/day) or both, for periods of 3 months, preceded by a double placebo period.

An unusual lightning flash at kennedy space center.

A lightning flash that struck the 150-meter weather tower at Kennedy Space Center was studied by several research groups using varioul techniques. The flash had unusually large peak currents and a stepped leader of relatively short duration. The charged regions neutralized by the three return strokes were located within a horizontal layer between heights of about 6 and 8 kilometers, where environmental temperatures were about -10 degrees to -20 degrees C.