We have measured the size of the releasable pools of LH and FSH in the pituitary glands of ovariectomized ewes in which the pituitary was isolated surgically from the hypothalamus. The ewes were given GnRH pulses (250 ng) every hour (N = 3) or every 2 h (N = 3) for 1 week and then given a high dose GnRH infusion (0.5 micrograms/min) for 4 h. Blood samples were collected to characterize the LH a...

High-frequency bipolar electric pulses have been shown to mitigate undesirable muscle contraction during irreversible electroporation (IRE) therapy. Here, we evaluate the potential applicability of such pulses for introducing exogenous molecules into cells, such as in electrochemotherapy (ECT). For this purpose we develop a method for calculating the time course of the effective permeability of...

The acceleration of ions from ultrathin (10-100 nm) carbon foils has been investigated using intense (∼6×10^{20} W  cm^{-2}) ultrashort (45 fs) laser pulses, highlighting a strong dependence of the ion beam parameters on the laser polarization, with circularly polarized (CP) pulses producing the highest energies for both protons and carbons (25-30  MeV/nucleon); in particular, carbon ion energi...

We investigate experimentally the collisions of nonlinear envelope pulses in a left-handed transmission line with regularly spaced Schottky varactors. By measuring the test line, we successfully observed that when two nonlinear envelope pulses traveling in opposite directions collide, two new envelope pulses are developed. These new pulses satisfy the phase-matching condition, and their carrier...

Introduction Although high-field MRI on the human head offers a number of advantages including increased signal-to-noise ratio (SNR), and higher contrast for certain applications, there are also significant difficulties. Chief among these are the non-uniform tipping (variation of the flip angle in the sample) produced by conventional RF pulses due to the inhomogeneous RF (B1) field intrinsic in...

We present a numerical study of the pulses displayed by a semiconductor laser with optical feedback in the short-cavity regime, such that the external cavity round-trip time is shorter than the laser relaxation oscillation period. For certain parameters there are occasional pulses, which are high enough to be considered extreme events. We characterize the bifurcation scenario that gives rise to...

Giant radio pulses of the millisecond pulsar B1937+21 were recorded with the S2 VLBI system at 1.65 GHz with NASA/JPL’s 70-m radio telescope at Tidbinbilla, Australia. These pulses have been observed as strong as 65 000 Jy with widths ≤ 15 ns, corresponding to a brightness temperature Tb ≥ 5 · 10 39 K, the highest observed in the universe. The vast majority of these pulses occur in a 5.8 μs and...

Resource pulses are occasional events of ephemeral resource superabundance that occur in many ecosystems. Aboveground consumers in diverse communities often respond strongly to resource pulses, but few studies have investigated the belowground consequences of resource pulses in natural ecosystems. This study shows that resource pulses of 17-year periodical cicadas (Magicicada spp.) directly inc...

We investigate the dynamics of the heterodimer autorepression loop (HAL), a small genetic module in which a protein A acts as an autorepressor and binds to a second protein B to form an AB dimer. For suitable values of the rate constants, the HAL produces pulses of A alternating with pulses of B. By means of analytical and numerical calculations, we show that the duration of A pulses is extreme...

We have carried out a survey for ‘giant pulses’ in 5 millisecond pulsars. We detect individual pulses from the high Ė pulsar PSR B1821−24 with energies exceeding 50× the mean pulse energy. These giant pulses are concentrated in a narrow phase window coincident with the power-law non-thermal pulse seen in hard X-rays. This is the third example of the giant pulse phenomenon. It supports the idea ...