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Ultra-high-energy physics is about to enter a new era thanks to the impressive results of experiments such as the Large High Altitude Air Shower Observatory, detecting photons of up to $$1.4\times 10^{15}$$ 1.4 × 10 15  eV (PeV scale). These new results could be used to test deviations with respect to special relativity. While this has been already explored within the approach of Lorentz Invariance Violation theories, in this work we consider, for the first time, modifications due to a relativistic deformed kinematics (which appear in Doubly Special Relativity, or DSR, theories). In particular, we study the mean free path of very high-energy photons due to electron-positron pair creation when interacting with low-energy photons of the cosmic microwave background. Depending on the energy scale of the relativistic deformed kinematics, present (or near future) experiments can be sensitive enough to be able to identify deviations from special relativity.

Motilin is secreted in a clear episodic pattern during fasting or during the interdigestive phase, but feeding promptly stops this secretory pattern, and plasma concentrations of motilin decrease. We have previously determined that fasting markedly suppresses pulsatile luteinizing hormone (LH) secretion in female rats in the presence of oestrogen. In the present study, we wished to learn if motilin may mediate the fasting-induced suppression of LH secretion by determining the effects of motilin administration on LH release and on food intake. Intravenous (i.v.) injection of motilin (37 nmol/rat) suppressed LH release and significantly decreased mean LH concentrations both in ovariectomized (OVX) and oestradiol-implanted ovariectomized (OVX+E2) rats. Food intake was significantly increased by i.v. motilin injection in OVX rats, but not in OVX+E2 rats. It is likely that motilin inhibits LH release via inhibition of the gonadotrophin-releasing hormone (GnRH)-releasing mechanism at the hypothalamic level, because motilin (3.7 nmol/rat) also suppressed LH secretion when centrally administered, and because LH release in i.v. motilin-treated rats increased in response to exogenous GnRH. These results suggest that motilin may be a peripheral signal for the suppression of LH secretion through central sensors.

This article endeavors to go deeply into the recent transformations that have taken place in the regulation of street-level economic and business activities in Mexico City. It draws upon data collected during the course of a threeyear research project carried out from 2007 to 2009, a specific timeframe when the urban authority deployed different legal and repressive strategies in order to 'clean-up' the streets of the city's downtown areas, in keeping with the Giuliani Group's advice. This paper intends to clarify two different dynamics: (a) how the urban authorities went about applying Giuliani's advice to clean up the streets, and (b) the consequences these initiatives may have on the historical downtown core. My principal task is to offer a tentative insight into whether the incorporation of Giuliani's repressive approach to urban planning has affected a specific urban space where, for decades, street-level economic, business and trade activities have been intimately interrelated with the creation of a city's street culture. Research findings suggest that in those countries where street economic activities constitute a die-hard method of eking out one's sustenance, the relation between order and crime may be more porous and indeterminate than is recognized and acknowledged by the majority of sociolegal studies that have, over the course of time, developed around this topic.

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