To determine the mechanism of ventricular vulnerability to electrical stimulation, we simultaneously recorded from 120 transmural electrodes in a 35 X 20 X 5-mm portion of right ventricular infundibulum in seven dogs. Baseline pacing (S1) was performed from outside the mapped region followed by single premature stimulation (S2) of increasing strength at the center of the mapped region. In five ...

A partially dominant mutation exhibiting increased tolerance to cyclohexanedione and aryloxyphenoxypropionate herbicides was isolated by exposing susceptible maize (Zea mays) tissue cultures to increasingly inhibitory concentrations of sethoxydim (a cyclohexanedione). The selected tissue culture (S2) was greater than 40-fold more tolerant to sethoxydim and 20-fold more tolerant to haloxyfop (an...

We study the enhancement of two-photon absorption (TPA) in a series of porphyrins and tetraazaporphyrins by measuring the absolute TPA cross sections with 100-fs-duration pulses in two ranges of laser wavelengths, from 1100 to 1500 and from 700 to 800 nm. The cross section in the Q transition region is s2 ; 1 – 10 GM (where 1 GM 5 10250 cm4 s21 photons21), a value that is explained by partial l...

OBJECTIVES To investigate whether accommodation to depolarising and hyperpolarising currents differs for motor axons of human upper and lower limb nerves. METHODS The threshold tracking technique was used to measure threshold electrotonus for median and peroneal motor axons. The threshold current that produced a compound muscle action potential 50% of maximum was measured, and membrane potent...

In this supplement we would like to discuss certain qualitative and quantitative aspects of the k-core decomposition, how these are related to the other global topological features of the network and how we have used them in deciding upon a length distribution for the PR regions. We would also like to warn, here against an undue emphasis on the visual appearance of the k-core decomposition, whi...

To learn more about controlling renal interstitial hydrostatic pressure (RIHP), we assessed its response to renal medullary direct interstitial volume expansion (rmDIVE = 100 μL bolus infusion/30 sec). Three experimental series (S) were performed in hydropenic, anesthetized, right-nephrectomized, acute left renal-denervated and renal perfusion pressure-controlled rats randomly assigned to group...

A focal visual stimulus outside the classical receptive field (RF) of a V1 neuron does not evoke a spike response by itself, and yet evokes robust changes in the local field potential (LFP). This subthreshold LFP provides a unique opportunity to investigate how changes induced by surround stimulation leads to modulation of spike activity. In the current study, two identical Gabor stimuli were s...

Content General methods .............................................................................................................................................. S1 Apparatus ......................................................................................................................................................... S2 Abbreviations..................................................

OBJECTIVES The present in vivo study was designed to assess the efficacy of 3 root canal disinfection protocols in immature dog teeth with apical periodontitis (AP). MATERIAL AND METHODS Forty immature premolars with pulp necrosis and AP of five Beagle dogs were used. Three experimental disinfection protocols were established. After irrigation with 40 ml 5.25% sodium hypochlorite using the En...