A proof-of-concept superregenerative QPSK transceiver

In this paper we present a description and experimental verification of an HF-band proof-of-concept superregenerative transceiver for QPSK signals. We describe a simple implementation of an all-digital, FPGA-based, QPSK transmitter section. On the receiver side, the quench signal is generated in the same FPGA with a minimum of analog circuitry. As the main novelty, we present a simple synchronization scheme suitable for packetized transmissions.Peer ReviewedPostprint (author’s final draft

Testicular spermatozoa and male germ cells evolution in "Dina lineata" (Hirudinea: Erpobdellidae) studied by scanning electron microscopy

A Dina lineata, hirudini erpobdèllid amb fecundació traumàtica hipodèrmica, cada espermatogònia primitiva, lliure en els sacs testiculars, entra en un procés de set divisions mitòtiques anticlinals cariocinètiques i no citocinètiques per formar poliplasts amb 2, 4, 8, 16, 32, 64 espermatogònies i, finalment, 128 espermatòcits primaris. Les cel•lules, en un mateix poliplast, evolucionen sincrònicament lligades per un pont a una massa citoplasmàtica central comuna anomenada citòfor. Una darrera divisió, meiòtica, porta a un poliplast amb 512 espermàtides. Per un complex procés morfogenètic de diferenciació cel•lular, cada espermàtida, arrodonida i d'uns 1,3 µm de diàmetre, esdevé un espermatozoide filamentós i helicoïdal d'uns 48 µm de longitud per 0,3 µm de diàmetre. L'ordre cronològic de diferenciació de les diverses regions del gàmeta és el següent: elongació del flagel, elongació i espiralització del nucli, elongació de la regió mitocondrial i elongació i espiralització, primer de l'acrosoma posterior i, després, de l'acrosoma anterior. A l'espermatozoide: 1) L'acrosoma posterior (7 µm) és una doble hèlix dextrògira formada per dues fibres, una d'estreta i una altra d'ampla, que descriuen, cadascuna, set voltes completes. 2) L'acrosoma anterior (6,5 µm) és un eix a l'entorn del qual una mateixa expansió cintiforme descriu, en sentit dextrògir, set voltes completes. 3) La regió nuclear (5,5 µm) és també una doble hèlix dextrògira integrada per dues fibres. A la base presenten el mateix gruix, però, a mesura que se n'allunyen, l'alteren a voltes alternes. 4) Les regions mitocondrial (8,5 µm) i flagellar (20 µm) són externament llises.This paper studies the male germ cells evolution in the leech Dina lineata by scanning electron microscopy. A primitive spermatogonium is an oval cell measuring 1,6 per 6 µm. Seven not-finished consecutive anticlinal mitotic divisions lead to the formation of isogenic groups with 2, 4, 8, 16, 32, 64 spermatogonia and, finally, 128 primary spermatocytes. The cells are all clustered in only one group and they evolve gradually and synchronically, remaining connected by cytoplasmic bridges to a central cytoplasmic mass called cytophore. A last division, which is meiotic, gives rise to an isogenic group with 512 spermatids: the cellular body of each one is reduced to 1,3 µm in diameter. By means of a complex spermiogenic process of cellular differentiation, each body becomes a filiform and helicoid spermatozoon measuring 48 µm in length and 0.3 µm in diameter. The morphogenetic and chronologic sequence of the various regions is the following: flagellum elongation; nucleus spiralization and elongation; mitochondrial region elongation; and finally, spiralization and elongation, first of the posterior acrosome and after of the anterior acrosome. In the spermatozoon: 1) The posterior acrosome (7 µm) is a right-handed double helix integrated by two fibers: a narrow one and a wide one; each describes seven complete turns. 2) The anterior acrosome (6.5 µm) is a longitudinal axis which has a ribbonshaped expansion describing seven right-handed complete turns around the same axis. 3) The nuclear region (5.5 µm) is also a right-handed double helix integrated by two fibers. On their base they show the same trickness, but this is alternatively altered along it from the base to the other side. 4) The mitochondrial region (8.5 µm) and the flagellar one (20 µm) are externally smooth

Resveratrol metabolite profiling in clinical nutrition research-from diet to uncovering disease risk biomarkers: epidemiological evidence

Resveratrol is a bioactive plant compound that has drawn scientific and media attention owing to its protective effects against a wide variety of illnesses, including cardiovascular diseases and cancer. In the last two decades, a plethora of preclinical studies have shown these beneficial effects, and some of them have been supported by clinical trials. However, there are few epidemiological studies assessing these relationships, showing mostly inconsistent results among them. This could be partially due to the difficulty of accurately estimating dietary resveratrol exposure. The development of Phenol-Explorer, a database containing resveratrol food-composition data, will facilitate the estimation of resveratrol intake. Moreover, the discovery and validation of a nutritional biomarker of this exposure, urinary resveratrol metabolite profile, will allow a more accurate assessment of dietary resveratrol exposure. Few epidemiological studies have assessed the potential health effects of resveratrol. Resveratrol was not associated with total mortality, cancer, or cardiovascular events, but it was associated with an improvement of serum glucose and triglyceride levels and a decrease in heart rate. Together, these findings suggest a potential cardioprotective effect of resveratrol in epidemiological studies, although the evidence is still scarce

Entanglement in holographic dark energy models

We study a process of equilibration of holographic dark energy (HDE) with the cosmic horizon around the dark-energy dominated epoch. This process is characterized by a huge amount of information conveyed across the horizon, filling thereby a large gap in entropy between the system on the brink of experiencing a sudden collapse to a black hole and the black hole itself. At the same time, even in the absence of interaction between dark matter and dark energy, such a process marks a strong jump in the entanglement entropy, measuring the quantum-mechanical correlations between the horizon and its interior. Although the effective quantum field theory (QFT) with a peculiar relationship between the UV and IR cutoffs, a framework underlying all HDE models, may formally account for such a huge shift in the number of distinct quantum states, we show that the scope of such a framework becomes tremendously restricted, devoiding it virtually any application in other cosmological epochs or particle-physics phenomena. The problem of negative entropies for the non-phantom stuff is also discussed.Comment: 10 pages, version to appear in PL

Espacios híbridos, espacios humanos, para un futuro “viable”: revisitando la psicología ambiental

Llibre d'actes: Congrés Internacional de Psicologia Ambiental, que inclou el XII Congrés de Psicologia Ambiental (PsicAmb) i les VI Jornades Científiques de l'ArpEnv. Barcelona, 22-25 octubre 2013.Este libro es una recopilación de los trabajos presentados en el Congreso Internacional de Psicología ambiental “Espacios híbridos, espacios humanos, para un futuro “viable”: revisitando la Psicología ambiental”, celebrado en Barcelona los días 22 a 25 de octubre de 2013. En este encuentro se hizo coincidir el XII Congreso de Psicología de Psicamb (asociación que reúne la Psicología ambiental desarrollada en la Península Ibérica y las islas Canarias y Baleares) con las 6as jornadas científicas del ArpEnv (asociación de Psicología ambiental de la área francófona europea), además de estar abierto a las aportaciones de otros colegas de todo el mundo

Signal and noise power spectra in superregenerative oscillators

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a method to quantify noise in superregenerative oscillators. A frequency domain technique, originally intended to determine the signal response, can also be used to determine the noise response. This paper focuses on the procedure required to achieve this. Signal and noise spectra are obtained and their shape is compared. Finally, signal-to-noise ratio is computed for different quench signalsPeer ReviewedPostprint (author's final draft