IUDs are a highly effective method of contraception after unprotected intercourse. Because they are safe for the majority of women, highly effective and cost-effective when left in place as ongoing contraception, whenever clinically feasible IUDs should be included in the range of emergency contraception options offered to patients presenting after unprotected intercourse. This review is limited by the fact that the original studies did not provide sufficient data on the delay between intercourse and insertion of the IUD, parity, cycle day of intercourse or IUD type to allow analysis by any of these variables.

We propose a dielectrophoresis model for phase-separated manganites. Without increase of the fraction of metallic phase, an insulator-metal transition occurs when a uniform electric field applied across the system exceeds a threshold value. Driven by the dielectrophoretic force, the metallic clusters reconfigure themselves into stripes along the direction of electric field, leading to the filamentous percolation. This process, which is time-dependent, irreversible and anisotropic, is a probable origin of the colossal electroresistance in manganites.

We study the radio-frequency diagonal conductivities of the anisotropic stripe phases of higher Landau levels near half-integer fillings. In the hard direction, in which larger dc resistivity occurs, the spectrum exhibits a striking resonance, while in the orthogonal, easy direction, no resonance is discernible. The resonance is interpreted as a pinning mode of the stripe phase.

We report the observation of a resonance in the microwave spectra of the real diagonal conductivities of a two-dimensional electron system within a range of ∼ ±0.015 from filling factor ν = 1/3.The resonance is remarkably similar to resonances previously observed near integer ν, and is interpreted as the collective pinning mode of a disorder-pinned Wigner solid phase of e/3-charged carriers . * These authors contributed equally to this paper. Wigner solids occur in 2DES for small Landau level fillings (ν) [7][8][9], when the kinetic energy of carriers is quenched by the magnetic field, so that the carriers become effectively dilute, with their typical spacing larger than the magnetic length l B = (h/eB) 1/2 . At least for 2DES samples of extremely low disorder, Wigner solids can occur as well within the ranges of integer quantum Hall effect plateaus [10], in which there is a dilute population of electrons or holes in a partially filled Landau level, along with one or more completely filled Landau levels. Within the IQHE, Wigner solids are composed of carriers generated by moving ν away from its integer value, the insulating property of the pinned solid gives the quantized Hall plateau, which is concomitant with vanishing diagonal conductivity, its finite width.The pinning of the Wigner solid by residual disorder [11], besides causing them to be insulators and producing finite correlation lengths for crystalline order, gives rise to a striking rf or microwave resonance in the spectrum [10,[12][13][14][15][16]. This resonance is understood as a pinning mode, or a collective oscillation of solid domains within the disorder potential.Pinning modes [12] can be seen both in the low ν state [13][14][15], that terminates the FQHE series, and within IQHE's of samples with extremely low disorder [10,16]. This paper reports the observation of a microwave resonance within the ν range of the 1/3 FQHE. The resonance is interpreted as pinning mode of a Wigner solid of 1/3 charged excitations, and this interpretation is supported by a comparison of the parameters of the resonance near 1/3 with those of a pinning resonance observed near ν = 1 in the same sample.Both the resonance near ν = 1/3 and the resonance near ν = 1 show an increase of peak frequency, f pk , as quasiparticle charge density decreases, and the integrated absorptions 2 of both resonances suggest that much of the quasiparticle charge density is participating in the mode. The resonance around 1/3 occurs for fillings within ±0.015 of 1/3, much narrower than the ±0.16 range of resonance within the IQHE around ν = 1, and for the same quasiparticle number density,ñ, the resonance peak frequencies around 1 and 1/3 are nearly the same.The data presented are from a 2DES in a 50 nm wide GaAs/AlGaAs/GaAs quantum well (#7-20-99.1) with electron density n = 1.1 × 10 11 /cm 2 , and low temperature mobility µ = 15 × 10 6 cm 2 /Vs. The microwave spectroscopy technique is similar to those reported earlier [10,[12][13][14][15][16]. As illustrated in Fig. 1(a), we deposi...