Activity-driven Ca(2+) signaling plays an important role in a number of neuronal functions, including neuronal growth, differentiation, and plasticity. Both cytosolic and nuclear Ca(2+) has been implicated in these functions. In the current study, we investigated membrane-to-nucleus Ca(2+) signaling in cerebellar Purkinje neurons in culture to gain insight into the pathways and mechanisms that can initiate nuclear Ca(2+) signaling in this neuronal type. Purkinje neurons are known to express an abundance of Ca(2+) signaling molecules such as voltage-gated Ca(2+) channels, ryanodine receptors, and IP3 receptors. Results show that membrane depolarization evoked by brief stimulation with K(+) saline elicits a prominent Ca(2+) signal in the cytosol and nucleus of the Purkinje neurons. Ca(2+) influx through P/Q- and L-type voltage-gated Ca(2+) channels and Ca(2+)-induced Ca(2+) release (CICR) from intracellular stores contributed to the Ca(2+) signal, which spread from the plasma membrane to the nucleus. At strong K(+) stimulations, the amplitude of the nuclear Ca(2+) signal exceeded that of the cytosolic Ca(2+) signal, suggesting the involvement of a nuclear amplification mechanism and/or differences in Ca(2+) buffering in these two cellular compartments. An enhanced nuclear Ca(2+) signal was more prominent for Ca(2+) signals elicited by membrane depolarization than for Ca(2+) signals elicited by activation of the metabotropic glutamate receptor pathway (mGluR1), which is linked to Ca(2+) release from intracellular stores controlled by the IP3 receptor.

Sprites have been detected in video camera observations from Niger over mesoscale convective systems in Nigeria during the 2006 AMMA (African Monsoon Multidisciplinary Analysis) campaign. The parent lightning flashes have been detected by multiple Extremely Low Frequency (ELF) receiving stations worldwide. The recorded charge moments of the parent lightning flashes are often in excellent agreement between different receiving sites, and are furthermore consistent with conventional dielectric breakdown in the mesosphere as the origin of the sprites. Analysis of the polarization of the horizontal magnetic field at the distant receivers provides evidence that the departure from linear magnetic polarization at ELF is caused primarily by the day–night asymmetry of the Earth–ionosphere cavity. Copyright © 2009 Royal Meteorological Society

Simultaneous measurements of high‐altitude optical emissions and magnetic fields produced by sprite‐associated lightning discharges enable a close examination of the link between low‐altitude lightning processes and high‐altitude sprite processes. We report results of the coordinated analysis of high‐speed sprite video and wideband magnetic field measurements recorded simultaneously at Yucca Ridge Field Station and Duke University. From June to August 2005, sprites were detected following 67 lightning strokes, all of which had positive polarity. Our data showed that 46% of the 83 discrete sprite events in these sequences initiated more than 10 ms after the lightning return stroke, and we focus on these delayed sprites in this work. All delayed sprites were preceded by continuing current moments that averaged at least 11 kA km between the return stroke and sprites. The total lightning charge moment change at sprite initiation varied from 600 to 18,600 C km, and the minimum value to initiate long‐delayed sprites ranged from 600 for 15 ms delay to 2000 C km for more than 120 ms delay. We numerically simulated electric fields at altitudes above these lightning discharges and found that the maximum normalized electric fields are essentially the same as fields that produce short‐delayed sprites. Both estimated and simulation‐predicted sprite initiation altitudes indicate that long‐delayed sprites generally initiate around 5 km lower than short‐delayed sprites. The simulation results also reveal that slow (5–20 ms) intensifications in continuing current can play a major role in initiating delayed sprites.

Recent time‐resolved multi‐color photometric data obtained on one class of lightning‐related transient upper‐atmospheric electromagnetic events called sprites have confirmed an impulsive ionization emission during the sprite initiation. Data have also been obtained on some sprites which do not exhibit observable tendrils and which exhibit ionization emission that, if present, is below our detection limit. This suggests that some sprite events exhibit strong ionization while others do not. These results indicate that conditions causing sprite optical emissions are highly variable.

A six year record of optical observations of lightning-induced mesospheric transient luminous events (TLEs) is available from the Yucca Ridge Field Station (YRFS) near Ft. Collins, CO. Climatological analyses reveal sprites and elves occur in a variety of convective storm types, but principally mesoscale convective systems (MCSs) and squall lines. Severe supercell storms rarely produce TLEs, except during their dissipating stage. Few TLEs are observed during storms with radar echo areas <7,500 km2. Above this size there is a modest correlation with radar areal coverage. A typical High Plains storm produces 45 TLEs over a 143 interval. Sprites and most elves are associated with +CGs. The probability of a TLE increases with peak current. In six storms, 5.1% of +CGs produced TLEs, the number increasing to 32% of +CGs with >75 kA and 52% of +CGs with >100 kA peak current.

Ground flashes with positive polarity associated with both sprites and elves excite the Earth's Schumann resonances to amplitudes several times greater than the background resonances. Theoretical predictions for dielectric breakdown in the mesosphere are tested using ELF methods to evaluate vertical charge moments of positive ground flashes. Comparisons of the measured time constants for lightning charge transfer with the electrostatic relaxation time at altitudes of nighttime sprite initiation (50–70 km) generally validate the electrostatic assumption in predictions made initially by Wilson [1925]. The measured charge moments (Q dS = 200–2000 C‐km) are large in comparison with ordinary negative lightning but are generally insufficient to account for conventional air breakdown at sprite altitudes. The measured charge moments, however, are sufficient to account for electron runaway breakdown, and the long avalanche length in this mechanism also accounts for the exclusive association of sprites with ground flashes of positive polarity. The association of elves with large peak currents (50–200 kA) measured by the National Lightning Detection Network in a band pass beyond the Schumann resonance range is consistent with an electromagnetic pulse mechanism for these events.

The purpose of this study was to determine if oral creatine (CR) ingestion, compared to a placebo (PL), would enable swimmers to maintain a higher swimming velocity across repeated interval sets over 2 weeks of supplementation. Fourteen female and 18 male university swimmers consumed a PL during a 2-week baseline period. Using a randomized, double-blind design, during the next 2 weeks subjects consumed either CR or PL. Swimming velocity was assessed twice weekly during 6 X 50-m swims and once weekly during 10 X 25-yd swims. There was no effect of CR on the 10 X 25-yd interval sets for men and women and no effect on the 6 X 50-m interval sets for women. In contrast, for men, CR significantly improved mean overall swimming velocity in the 6 X 50-m interval after 2 weeks of supplementation, whereas PL had no effect. Although ineffective in women, CR supplementation apparently enables men to maintain a faster mean overall swimming velocity during repeated swims each lasting about 30 s; however, CR was not effective for men in repeated swims each lasting about 10 - 15 s.

56 This study assessed the ability of four different activity monitors' to discriminate small changes in walking speed and the utility of the activity monitors' estimation of energy expenditure(EE:when appropriate) compared to indirect calorimetry(IC-EE) while walking on a motor-driven treadmill. Twenty-four subjects walked at 2.0, 2.5, 3.0, 3.5, and 4.0 mph (0% grade) for separate 30-min periods. The Tritrac-R3D(TT), Computer Science and Applications, Inc.(CSA), Mini-Logger Series 2000(ML), and Yamax Digiwalker® 500(YX) were secured at the waistline of each subject. A CSA was also worn on the wrist and ankle. Each activity monitor detected significant changes in activity and IC-EE at each treadmill speed. For all speeds there were significant relationships between IC-EE and TT-EE(r=0.94), YX-EE(r=0.85), CSA hip(cts·min-1, r=0.77) and ML(cts·min-1, r=0.75). At all speeds TT-EE significantly overestimated EE by an average of 0.81 kcal·min-1. YX-EE significantly underestimated IC-EE at 2.0 mph (0.80 kcal·min-1) at 3.5 mph and above by an average of 0.32 kcal·min-1. For all speeds TT-EE explains 88% of the variance of IC-EE with standard error of the estimate(SEE) of 0.50 kcal·min-1. For all speeds, CSA hip and body mass as variates explains 85% of the variance of IC-EE with a SEE of 0.58 kcal·min-1 while ML and body mass as variates explains 76% of the variance of IC-EE with SEE=0.70 kcal·min-1. While all methods provided strong correlations between the respective method and IC-EE, TT-EE or CSA, with the knowledge of body mass, are likely the methods of choice to predict EE when walking on a level surface.

New observations of sprites (cloud‐ionosphere luminous discharges above thunderstorms) were made from the Yucca Ridge Field Station 20 km northeast of Fort Collins, Colorado, on the night of July 11–12, 1994, as part of a summer 1994 observing campaign. The sprites appeared above a moderate mesoscale convective complex mostly over Kansas at a range of about 270 km. The sprites were observed with both wide‐field and telescopic image‐intensified CCD TV cameras, a telescopic photometer system, and a 1‐ to 50‐kHz band VLF sferics receiver. This paper is based on five 1‐s data intervals containing bright sprites, smaller sprites, and cloud and sky flashes. Telescopic TV images of bright sprites had a fan‐shaped upper plume with very fine features not well resolved by the TV, but dendritic (upward forked) and vertically striated forms adjacent to these plumes and bright points of luminosity around the plume‐shaped regions. Many sprites consisted entirely of groups of vertically aligned striations which sometimes appeared to diverge from a common point of origin at cloud tops. All sprites in the present data sample were preceded by a cloud to ground (CG) stroke with a coincident sferic and sky flash. All CG strokes associated with sprites were positive, and most were 100 kA or more inferred peak current. From the photometer, the duration of the CG‐induced sky flashes was about 3 ms and the additional sprite total light curve was also about 3 ms. The puzzling feature that the total duration of TV images of sprites was often longer than the photometric values is discussed and an explanation given. The sprites were attributed to strong negative charging, following the positive CG stroke, of a localized cloud top region which produced an intense electric field and a luminous discharge in the cloud‐ionosphere region. The concept of “break‐even” electric fields suggested by McCarthy and Parks may explain discharge initiation with moderate field strengths.

MALIGNANT hyperthermia was first described fully in 1962, when Denborough and colleagues reported an episode in a patient with a fear of anesthesia prompted by the death of 10 of 24 relatives who had received general anesthesia.1 A genetic susceptibility to drug-induced malignant hyperthermia was confirmed by numerous subsequent reports.2 Malignant hyperthermia is a syndrome initiated by a hypermetabolic state of skeletal muscle. The underlying defect appears to be an idiopathic increase in the sarcoplasmic concentration of calcium ion.3 4 5 As a consequence, during general anesthesia total body oxygen consumption in patients with the syndrome increases two to three times as . . .