A Derivation of Three-Dimensional Inertial Transformations

The derivation of the transformations between inertial frames made by Mansouri and Sexl is generalised to three dimensions for an arbitrary direction of the velocity. Assuming lenght contraction and time dilation to have their relativistic values, a set of transformations kinematically equivalent to special relativity is obtained. The ``clock hypothesis'' allows the derivation to be extended to accelerated systems. A theory of inertial transformations maintaining an absolute simultaneity is shown to be the only one logically consistent with accelerated movements. Algebraic properties of these transformations are discussed. Keywords: special relativity, synchronization, one-way velocity of light, ether, clock hypothesis.Comment: 16 pages (A5), Latex, one figure, to be published in Found. Phys. Lett. (1997

Actualización en anticoncepción hormonal

La anticoncepción hormonal constituye el segundo método anticonceptivo más utilizado en nuestro país. Las principales novedades en cuanto a composición son la introducción del valerato de estradiol como componente estrogénico para mejorar la seguridad y de la drospirenona, progestágeno con acción antimineralocorticoide, que contrarresta la retención hidrosalina y ha sido aprobado como tratamiento del síndrome premenstrual. Para mejorar el cumplimiento se han propuesto el método de inicio inmediato y los regímenes de administración en ciclo prolongado o continuo que disminuyen los síntomas del periodo libre de hormona. La vía transdérmica presenta niveles séricos superiores de etinilestradiol que la oral lo que puede elevar el riesgo de tromboembolismo. Las innovaciones en la anticoncepción de emergencia son la pauta toma única de 1500 mcg de levonorgestrel y su dispensación sin receta. En este trabajo se revisan también los riesgos así como los criterios médicos de elegibilidad de la anticoncepción hormonalThe second more frequently used contraception method in our country is hormonal contraception. Innovations in composition include the introduction of estradiol valerate as estrogen element to improve safety, and oral contraceptives containing drospirenone that is a progestin with antimineraolcorticoid activity and has been approved for treating premenstrual syndrome. To improve compliance quick start and extended dose regimen, that decreases symptoms during hormonal free interval, have been proposed. With transdermal patch ethinylestradiol serum level is higher than with oral contraceptives therefore venous thromboembolism risk can be increased. Main innovations in emergency contraception are the 1500 mcg single dose of levonorgestrel regimen and the possibility of obtaining it without medical prescription. In this essay we also review severe adverse effects and medical eligibility criteria of hormonal contraceptio

Mersenne-Horadam identities using generating functions

The main object of the present paper is to reveal connections between Mersenne numbers $M_n=2^n-1$ and generalized Fibonacci (i.e., Horadam) numbers $w_n$ defined by a second order linear recurrence $w_n=pw_{n-1}+qw_{n-2}$, $n\geq 2$, with $w_0=a$ and $w_1=b$, where $a$, $b$, $p>0$ and $q\ne0$ are integers. This is achieved by relating the respective (ordinary and exponential) generating functions to each other. Several explicit examples involving Fibonacci, Lucas, Pell, Jacobsthal and balancing numbers are stated to highlight the results

A rotating cavity for high-field angle-dependent microwave spectroscopy of low-dimensional conductors and magnets

The cavity perturbation technique is an extremely powerful method for measuring the electrodynamic response of a material in the millimeter- and sub-millimeter spectral range (10 GHz to 1 THz), particularly in the case of high-field/frequency magnetic resonance spectroscopy. However, the application of such techniques within the limited space of a high-field magnet presents significant technical challenges. We describe a 7.62 mm x 7.62 mm (diameter x length) rotating cylindrical cavity which overcomes these problems.Comment: 11 pages including 8 figure