We present a novel setup that allows the observation of the geometric phase that accompanies polarization changes in monochromatic light beams for which the initial and final states are different (so-called non-cyclic changes). This Pancharatnam-Berry phase can depend in a linear or in a nonlinear fashion on the orientation of the optical elements, and sometimes the dependence is singular. Expe...

A case is presented of a man who castrated himself and who reported he had experienced cyclic changes in sexuality for 6 years. Developmental history, including physical factors of cryptorchidism and bilateral inguinal hernias in infancy, suggests a setting in which comfortable masculine identification would have been most difficult. The feminine components of personality appear to have receive...

Adenosine 3':5'-cyclic monophosphate (cyclic AMP) has been shown to have an antimitotic role in various cell types, and it has been hypothesized that a decrease of cyclic AMP concentration in the cell initiates or permits cell division. This hypothesis has been evaluated with respect to clonal proliferation of lymphocytes. Two potent mitogenic agents, phytohemagglutinin and concanavalin A, whic...

The speed of the bacterial flagellar motor is thought to be regulated by structural changes in the motor. Two new studies, Boehm et al. (2010) in this issue and Paul et al. (2010) in Molecular Cell, now show that cyclic di-GMP also regulates flagellar motor speed through interactions between the cyclic di-GMP binding protein YcgR and the motor proteins.

Several hypotheses have been proposed to explain cyclic fluctuations in abundance of some small mammal populations. These hypotheses have been controversial, however, and there is no consensus among biologists as to why population cycles occur. In a demographically based model, we tested the potential influence of phase-specific changes in life history traits (age at maturity, fertility, juveni...

We have used spin-labels to detect prostaglandin E induced changes in erythrocyte membranes. The observed changes in spin-label resonance spectra can be mimicked in erythrocyte ghosts by loading them with cAMP or cGMP. These changes can also be observed by adding either of these cyclic nucleotides to intact cells. This entry of cyclic nucleotides into intact cells is blocked by an inhibitor of ...

The purpose of the present study was to determine whether the cyclic variation of integrated backscatter is measurable and quantifiable in all left ventricular walls and whether the information obtained using both parasternal and apical transducer positions can be used to identify changes in myocardial structure and contractility. The cyclic variation of integrated backscatter was measured from...