Storing single photons emitted by a quantum memory on a highly excited Rydberg state

Strong interaction between two single photons is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photonic quantum gates and deterministic Bell-state measurements. In the context of quantum networks, it would be important to achieve interactions between single photons from independent photon pairs storable in quantum memories. So far, most experiments showing nonlinearities at the single-photon level have used weak classical input light. Here we demonstrate the storage and retrieval of a paired single photon emitted by an ensemble quantum memory in a strongly nonlinear medium based on highly excited Rydberg atoms. We show that nonclassical correlations between the two photons persist after retrieval from the Rydberg ensemble. Our result is an important step towards deterministic photon–photon interactions, and may enable deterministic Bell-state measurements with multimode quantum memories.Peer ReviewedPostprint (published version

A DNA element recognised by the molybdenum-responsive transcription factor ModE is conserved in Proteobacteria, green sulphur bacteria and Archaea

BACKGROUND: The transition metal molybdenum is essential for life. Escherichia coli imports this metal into the cell in the form of molybdate ions, which are taken up via an ABC transport system. In E. coli and other Proteobacteria molybdenum metabolism and homeostasis are regulated by the molybdate-responsive transcription factor ModE. RESULTS: Orthologues of ModE are widespread amongst diverse prokaryotes, but not ubiquitous. We identified probable ModE-binding sites upstream of genes implicated in molybdenum metabolism in green sulphur bacteria and methanogenic Archaea as well as in Proteobacteria. We also present evidence of horizontal transfer of nitrogen fixation genes between green sulphur bacteria and methanogenic Archaea. CONCLUSIONS: Whereas most of the archaeal helix-turn-helix-containing transcription factors belong to families that are Archaea-specific, ModE is unusual in that it is found in both Archaea and Bacteria. Moreover, its cognate upstream DNA recognition sequence is also conserved between Archaea and Bacteria, despite the fundamental differences in their core transcription machinery. ModE is the third example of a transcriptional regulator with a binding signal that is conserved in Bacteria and Archaea

Futurs especulatius de l'art «Què passaria si...?»

Peer-reviewedApproaching art from a speculative point of view also involves thinking about other possible worlds beginning in the invention of futures that defy the logic of continuity and that can still surprise us. It means asking ourselves «what would happen if...», and completing the second part of the sentence as might the «idiot», that conceptual character able to generate the interstice from which other questions emerge, questions for which the conclusions can neither be taken for granted nor can it be assumed that the seeking for their meanings was exhausted. To speculate is to formulate these questions in the form of future fictions and to seek out possible responses without being ashamed of the uncertainty or faltering attempts. To speculate about the future is also to speculate about the present and the past, to create contemporary fables, far-reaching accounts that induce thought.Abordar el arte desde lo especulativo implica también pensar otros mundos posibles a partir de la invención de futuros que escapen a la lógica de la continuidad y que sigan teniendo la posibilidad de sorprendernos. Significa preguntarnos por el «qué pasaría si...» completando la segunda parte de la frase tal y como lo haría el «idiota», aquel personaje conceptual capaz de generar el intersticio para la emergencia de otras preguntas, aquellas que no dan por sentadas las conclusiones, ni presuponen agotados los significados de aquello que se busca conocer. Especular es formular esas preguntas en forma de ficciones de futuro y buscar respuestas posibles sin avergonzarnos de la duda ni el balbuceo. Especular sobre el futuro es también hacerlo sobre el presente y el pasado, crear fabulaciones contemporáneas, relatos densos que conducen al pensamiento.Abordar l'art des de l'aspecte especulatiu implica pensar també altres possibles mons, a partir de la invenció de futurs que escapen a la lògica de la continuïtat i que guarden la possibilitat de sorprendre'ns. Vol dir preguntar-nos pel «què passaria si...» i completar així la segona part de la frase tal com ho faria l'«idiota», aquell personatge conceptual capaç de generar l'interstici per a l'emergència d'altres preguntes, les que no donen per fet les conclusions ni pressuposen esgotats els significats d'allò que es busca conèixer. Especular és formular aquestes preguntes en forma de ficcions de futur, i buscar-hi respostes possibles sense avergonyir-nos del dubte ni del balboteig. Especular sobre el futur és fer-ho també sobre el present i el passat, crear fabulacions contemporànies, relats densos que condueixen al pensament

Video didàctic per comprendre la cromatografia : utilització de la tècnica d'hplc per la determinació de canvis en la síntesi d'un neurotransmissor : la histamina

La finalitat principal del vídeo realitzat correspon a un dels objectius docents que proposàvem en el projecte que ens va ser concedit per l'AGAUR: que l'alumne es pugui acostar a tècniques sofisticades que per la seva complexitat o perillositat no poden realitzar-se en els laboratoris de docència. També com a segon objectiu, pretenem que l'alumne comprengui millor conceptes que s'expliquen a teoria. En la situació actual, els alumnes de primer curs de medicina realitzen pràctiques de laboratori en que apliquen la cromatografia en capa fina per la separació de molècules i l'anàlisi qualitatiu de la seva presència en mostres tissulars. Malgrat que els principis teòrics són bàsicament els mateixos, és impossible en la pràctica realitzar cromatografies d'alta resolució (HPLC) que són comunament utilitzades per la quantificació de molècules diverses, no només en la recerca bàsica sinó en el laboratori clínic. Per altra banda, els alumnes de tercer i quart curs de la llicenciatura de bioquímica coneixen les bases teòriques de l'HPLC però tampoc en els laboratoris de pràctiques pot realitzar-se cromatografies d'alta resolució degut al grau de complexitat i despesa que comporten

Agencia y Materialidad en la Documentación del Arte de los Medios

El arte de los medios goza de una larga y fértil historia que ha generado innumerables prácticas artísticas de gran calidad así como no pocos estudios teóricos e históricos sobre las diferentes tendencias, creadores, o sobre las diferentes zonas geográficas que han intervenido e intervienen en la construcción de su pasado y su presente (Wilson,2001; Paul, 2003; Daniels, 2004, 2005; Popper, 2007; Grau, 2007; Alsina, 2007; Shanken 2009). No obstante las própias características y el componente experimental inherente a este conjunto de prácticas también ha aportado importantes preguntas relativas a la transformación de la naturaleza de los procesos que el arte de los medios introduce en las formas tradicionales de habérselas con el arte y el mundo del arte. El propósito de este artículo es incidir específicamente en aquellos procesos vinculados a la construcción de archivos y documentación, así como tambien a la propia conservación del arte de los medios, a través de un análisis de la problemática de la materialidad y la agencia en las prácticas artísticas . La perspectiva que adoptaremos no se limitará a la discusión técnica de las diferentes soluciones a las problemáticas planteadas por las mismas prácticas sino más bien a la problematización del problema mismo desde la perspectiva de la arqueología de los medios (Kittler, 1997; Ernst 2005; Zielinski, 2006; Huhtamo, Parikka, 2011); y el conjunto de reflexiones vinculadas al denominado nuevo materialismo (Delanda, 2000; Barad, 2003; Law, 2007; Coole, 2010).Media Art practices have a long and fertile history of artworks, projects and theoretical reflection that raised fresh perspectives in the connection between art and other disciplines, as well as the relation between art with life, society or political commitment. At the same time, media art projects made use of different methodologies that challenge the "how to do" of the whole contemporary art world. In this broad fluctuating context for arts, the present article focuses on documentation, preservation and archival processes. In order to analyse and problematise the issue of (media) art duration and transmission, we use as a vehicle the notions of agency and materiality. These multifaceted concepts (i.e. agency and materiality) will be approached using the Media Archaeology perspective (Kittler, 1997; Ernst 2005; Zielinski, 2006; Huhtamo, Parikka, 2011) combined with references encountered in the so-called New Materialism turn (Delanda, 2000; Barad, 2003; Law, 2007; Coole, 2010)

Spatio‐temporal responses of butterflies to global warming on a Mediterranean island over two decades

1. One very conspicuous sign that warming is affecting the ecology of butterflies are the phenological advances occurring in many species. Moreover, rising temperatures are having a notable impact – both negative and positive – on population abundances. To date, patterns have generally been analysed at species level without taking into account possible differences between populations, which, when they are noted, are mostly attributed to large‐scale climate differences across a latitudinal gradient. 2. We use a long‐term database (18 years) of butterflies from five sites of the island of Menorca (Balearic Islands, Spain) to investigate how phenology and population dynamics have been affected by climate warming during the past two decades. 3. Both species' phenology and abundance respond differently to warming at a local scale depending on the season. Rising temperatures in spring give rise to greater advancement of the phenology, whereas warming affects population abundance negatively in summer. Additional variability of responses among sites suggests that habitats are involved in the modulation of the aforementioned seasonal effect. 4. We discuss how the effects of temperature could be partially offset in more inland habitats such as forests or deep ravines, especially the latter which represent particularly fresh and humid environments. The positive effect of temperature on ravine populations during the summer suggests that butterflies disperse across habitats as a response to rising temperatures during the season. This dispersal behaviour as a response to warming could be especially important in island ecosystems where the possibilities of modifying altitudinal or latitudinal distributions are often severely limited.PC is funded by a PhD fellowship financed by the Govern de les Illes Balears (FPI‐CAIB‐2018). This work is framed within project GLC2017‐88122‐P financed by the Spanish Ministry of Science and Innovation to AT. The Catalan Butterfly Monitoring Scheme is funded by the Departament de Territori i Sostenibilitat de la Generalitat de Catalunya.N

Rivoflavin may interfere with on-line monitoring of secreted green fluorescence protein fusion proteins in Pichia pastoris

Background: Together with the development of optical sensors, fluorometry is becoming an increasingly attractive tool for the monitoring of cultivation processes. In this context, the green fluorescence protein (GFP) has been proposed as a molecular reporter when fused to target proteins to study their subcellular localization or secretion behaviour. The present work evaluates the use of the GFP fusion partner for monitoring extracellular production of a Rhizopus oryzae lipase (ROL) in Pichia pastoris by means of 2D-fluorimetric techniques. Results: In this study, the GFP-ROL fusion protein was successfully produced as a secreted fusion form in P. pastoris batch cultivations. Furthermore, both the fusion enzyme and the fluorescent protein (GFP S65T mutant) retained their biological activity. However, when multiwavelength spectrofluorometry was used for extracellular fusion protein monitoring, riboflavin appeared as a major interfering component with GFP signal. Only when riboflavin was removed by ultrafiltration from cultivation supernatants, GFP fluorescence signal linearly correlated to lipase activity. Conclusion: P. pastoris appears to secrete/excrete significant amounts of riboflavin to the culture medium. When attempting to monitor extracellular protein production in P. pastoris using GFP fusions combined with multiwavelength spectrofluorimetric techniques, riboflavin may interfere with GFP fluorescence signal, thus limiting the application of some GFP variants for on-line extracellular recombinant protein quantification and monitoring purposes

Editorial: pattern formation in biology

Over the past two decades, the study of pattern formation in biology has attracted the attention of many scientists from diverse fields, ranging from developmental biology, cell biology and synthetic biology, to physics, mathematics and computer science. Quantitative and interdisciplinary approaches have become essential for understanding these challenging phenomena. This Research Topic contains a collection of articles and reviews that use quantitative and interdisciplinary perspectives to understand the underlying mechanisms driving biological pattern formation. Modeling morphogenetic processes, gene regulatory network dynamics and morphogen gradients link the articles of this Research Topic, with a focus on three research areas: 1) underlying mechanisms of patterning processes; 2) cross-talk of morphogenetic and pattern formation processes, and 3) mathematical methods for modeling and quantifying biological patterning and morphogenesis. Below, each of the present Research Topic papers is briefly discussed.Centro Regional de Estudios Genómico

Impact of laser attacks on the switching behavior of RRAM devices

The ubiquitous use of critical and private data in electronic format requires reliable and secure embedded systems for IoT devices. In this context, RRAMs (Resistive Random Access Memories) arises as a promising alternative to replace current memory technologies. However, their suitability for this kind of application, where the integrity of the data is crucial, is still under study. Among the different typology of attacks to recover information of secret data, laser attack is one of the most common due to its simplicity. Some preliminary works have already addressed the influence of laser tests on RRAM devices. Nevertheless, the results are not conclusive since different responses have been reported depending on the circuit under testing and the features of the test. In this paper, we have conducted laser tests on individual RRAM devices. For the set of experiments conducted, the devices did not show faulty behaviors. These results contribute to the characterization of RRAMs and, together with the rest of related works, are expected to pave the way for the development of suitable countermeasures against external attacks.Postprint (published version