A Simultaneous Random Walk Game

Two tokens are placed on vertices of a graph. At each time step, one token is chosen and is moved to a random neighboring point. In previous work, Tetali and Winkler studied the Angel strategy for bringing the tokens together as quickly as possible (on average), and the Demon strategy for delaying their collision as long as possible (on average). We build on these results by studying a game version of this process. In our game, two players take turns choosing the token to move. The Angel player hopes to bring the tokens together while the Demon player tries to keep them apart. We present optimal strategies for both players on stars, different types of directed cycles, and paths. Our proofs employ couplings of random walks as well as strategy stealing arguments

Formative assesment in the classroom: Discursive analysis of the feedback activity in supervised practice of undergraduate educational psychologists

Este es un estudio discursivo sobre las evaluaciones formativas ocurridas en una actividad de retroalimentación como parte de la Práctica Supervisada de estudiantes de psicología educativa en una universidad pública de México (UNAM). Aunque se ha reconocido el valor que tiene la formación en la práctica de los psicólogos, hay pocos estudios que muestren cómo ocurren las prácticas de evaluación formativa en el aula. Debido a ello, nuestro objetivo es analizar los procesos de trabajo interaccional involucrados en una actividad de retroalimentación, cuando los estudiantes se convierten en evaluadores de la competencia o habilidades psico-educativas, en modalidades de la evaluación formativa como (a) la coevaluación, (b) la evaluación entre pares y (c) la autoevaluación. Para ello, analizaremos diversos episodios interaccionales que ocurren en el aula, después que ha ocurrido una primera sesión de orientación psico-educativa en una cámara de Gesell, y los participantes (maestra, pasante y estudiantes) se reúnen y evalúan la competencia profesional de una estudiante que fungió como psicóloga a cargo del caso. Para orientar el análisis, se recurre a un enfoque analítico discursivo, informado por la etnometodología y el análisis de la conversación, que permite examinar, momento a momento, las evaluaciones formativas sobre el trabajo de la psicóloga y los distintos posicionamientos que se hacen públicos alrededor de su desempeño. Los resultados muestran que en esta práctica supervisada se construye colectivamente una evaluación formativa en la que tanto la estudiante psicóloga encargada del caso como el pasante y el resto de las estudiantes que observaron y participaron en la evaluación tienen oportunidad de mejorar su desempeño profesional a través de la interacción discursiva que se desarrolla en el proceso. Esto permite reconocer la importancia de este tipo de análisis para estudiar la evaluación de las prácticas supervisadas y su valor formativo en situaciones realesThis is a discursive study of the formative assessments as feedback activities that take place as part of the Supervised Practice of undergraduate educational psychologists at a Mexican public university (UNAM). The formative practice of undergraduate psychologists has been recognized as very important, however there are few studies that show how are they evaluated as a formative practice at the classroom. Analyze the processes of interactional work involved in a feedback activity, when students become evaluators of competence or psycho-educational skills, in modalities of formative assessment such as (a) co-evaluation, (b) peer evaluation and (c) self-evaluation, is this work purpose. After the first psycho-educative session at the Gesell camera several classroom interactional extracts were analysed, where the participants (the teacher, an intern and undergraduates) evaluate the professional competence of an undergraduate student that work as the psychologist of a particular case. A discursive approach informed by the ethnometodology and the conversation analysis perspective orients the study in order to exam, turn by turn, the formative assessments of the undergraduate psychologists work and the public positions about her performance. The analysis results show the collective construction of the formative assessments of the supervised practice realised by a psychologist student. This psychologist together with a passant are in charge of the case and the rest of the students observe and participate in the assessment of the supervised practice. Through these collective discursive processes, all the participants have the opportunity to improve their professional performance. This results show the important contribution of this kind of analysis in order to describe and recognize the formative contribution of the supervised practices evaluated in real setting

Photoactive Nanomaterials Inspired by Nature: LTL Zeolite Doped with Laser Dyes as Artificial Light Harvesting Systems

The herein reported work describes the development of hierarchically-organized fluorescent nanomaterials inspired by plant antenna systems. These hybrid materials are based on nanostructured zeolitic materials (LTL zeolite) doped with laser dyes, which implies a synergism between organic and inorganic moieties. The non-interconnected channeled structure and pore dimensions (7.1 angstrom) of the inorganic host are ideal to order and align the allocated fluorophores inside, inferring also high thermal and chemical stability. These artificial antennae harvest a broad range of chromatic radiation and convert it into predominant red-edge or alternatively white-light emission, just choosing the right dye combination and concentration ratio to modulate the efficiency of the ongoing energy transfer hops. A further degree of organization can be achieved by functionalizing the channel entrances of LTL zeolite with specific tailor-made (stopcock) molecules via a covalent linkage. These molecules plug the channels to avoid the leakage of the guest molecules absorbed inside, as well as connect the inner space of the zeolite with the outside thanks to energy transfer processes, making the coupling of the material with external devices easier.This work was supported by the Basque Government (IT912-16) and Spanish MICINN (MAT2014-51937-C3-3-P) projects. Leire Gartzia also thanks the Basque Goberment for a Post-doctoral grant. Yi Xiao from Dalian University (China) is kindly acknowledged for the supply and synthesis of the stopcock molecule

Luminiszentzia, baliabide aproposa ioien eta biomolekulen presentzia agerian jartzeko

An efficient and high-resolution sensing of biomolecules and ions is of paramount relevance in biomedicine not only to monitor biochemical processes, but also to unravel the underlying mechanisms in diseases and find new drugs against them. Between the tested approaches to this aim, luminescence outstands as a suitable tool to gather such chemical information as an analytical signal, endowed with high sensitivity and specificity. The change of the fluorescence signal allows the visualization of the target molecules and its quantification as well. Therefore, fluorescent sensor can be developed applying dye chemistry, after anchoring a suitable receptor to a given chromophore. Herein, we disclose key guidelines to take into account in the design of such sensors. As a matter of fact, hereafter, we describe two BODIPY fluorophores based sensors to detect cations and amino acids. The monitorization is carried out following the change of the fluorescence efficiency and colour, respectively, being both of them properties easily visualized by the naked eye.; Biomolekulen eta ioien detekzio sentikorra eta eraginkorra premiazkoa da biomedikuntzan, ez soilik prozesu biokimikoak aztertzeko, baita gaixotasun mekanismoak ulertzeko eta sendagaiak bilatzeko ere. Eskuragarri dauden detekzio tekniken artean, luminiszentzia baliabiderik aproposenetariko bat da informazio kimiko hori lortzeko seinale analitiko gisa sentikortasun eta espezifikotasun ezin hobeak bermatzen baititu. Fluoreszentzia aldaketei jarraituz aztertu beharreko molekularen presentzia detektatzeaz gainera, beraren kantitatea ere kuantifika daiteke. Beraz, koloratzaileen kimika moldakorraz baliatuz, sentsore fluoreszenteak gara daitezke kromoforo bati aproposa den hartzaile espezifikoak lotuz. Lan honetan, holako sentsoreak diseinatzeko kontuan hartu behar diren irizpide orokorrak aipatzen dira. Azken hori agerian jartzeko, BODIPY koloratzailean oinarritutako bi sentsore fluoreszente deskribatzen dira, katioiak eta aminoazidoak detektatzeko gai direnak. Euren presentzia eta kantitatea aztertzeko fluoreszentzia ahalmena eta kolore aldaketa ikuskatzen dira, hurrenez hurren, biak begi bistaz erraz behatzen diren fenomenoak izanik

Reproductive Tactics of Sexes and Fitness in the Dragonfly, Diastatops obscura

The sexual selection strategies of territorial Odonata that do not present courtship behavior is still not completely understood, especially the role of the females. Diastatops obscura Fabricius (Odonata: Libellulidae) females participate in mate selection in a passive manner, allowing copulation with the first male that captures them and afterwards choosing whether to oviposit or not. This study introduces the idea of female passive choice as an adaptative tactic in intersexual selection. Also discussed is the adaptative value of this tactic and its flexibility according to environmental conditions and reproductive strategies adopted by the males. A natural population of Diastatops obscura was observed in the Pitimbu River of northeast Brazil. Focal continuous and ad libitum techniques were used to record attempted copulation, copulation, and oviposition behavior, in addition to registering male territoriality. An estimate of individual reproductive success (IRS) was obtained by recording 187 reproductive events. Territorial males, mainly occupying areas near the river margin, achieved greater copulation and oviposition success (IRS = 0.371) than did satellite males (IRS = 0.028). Females that copulated with territorial males experienced, for the most part, only one copulation and oviposition event, while those that copulated with satellite males fled or performed a second copulation with a territorial male. Thus, the best tactic adopted by the D. obscura males was to occupy a territory providing the greatest access to females, while the females used passive choice for fitness optimization

Liquid-crystalline, liquid-ordered, rippled and gel lipid bilayer phases as observed with nile red fluorescence

The basic matrix of cellular membranes consists of a double layer (bilayer) of phospholipids. Semisynthetic lipid bilayers are commonly used in biophysical studies of membranes. According to tem-perature and composition, lipid bilayers can exist in liquid-crystalline (or liquid-disordered), liquid -ordered, rippled, and gel phases. In the present study, the hydrophobic, solvatochromic molecule Nile red has been used as a fluorescent probe to examine the physical state of bilayers of different composi-tions in the 15-60 degrees C range. Phospholipids with saturated or unsaturated acyl chains, in the presence or absence of cholesterol have been studied. Nile red shows absorption maxima at 520-550 nm and emis-sion maxima at 580-640 nm, single photon excitation not being damaging to the system. A red/orange intensity ratio (ROIR) index has been used to normalize the results. ROIR varies clearly and reproducibly with the lipid phase, increasing in the order: liquid-ordered < gel < rippled < liquid-crystalline. It increases with temperature and decreases with cholesterol contents in the bilayers. Nile red allows an unusually clear observation of the rippled-to-liquid crystalline phase transition in saturated phospho-lipids. FLIM studies with Nile red also show differences between lamellar phases. Rotational relaxation times have been determined for Nile red in liquid-disordered (0.72 +/- 0.010 ns), gel (1.16 +/- 0.070 ns), and liquid-ordered (1.79 +/- 0.14 ns) phases, the large value of the liquid-ordered phase being an indication of the sterol hindering probe tumbling in the hydrophobic matrix.This work was supported in part by the Spanish Ministerio de Ciencia e Innovación (MCI), Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (grants No. PGC2018-099857-B-I00, PID2020-114755GB-C33 ), by the Basque Government (grants No. IT1625-22, IT1639-22,and IT1270-19), by Fundación Ramón Areces (CIVP20A6619), by Fundación Biofísica Bizkaia, and by the Basque Excellence Research Centre (BERC) program of the Basque Government

A Computational-Experimental Approach to Unravel the Excited State Landscape in Heavy-Atom Free BODIPY-Related Dyes

We performed a time-gated laser-spectroscopy study in a set of heavy-atom free single BODIPY fluorophores, supported by accurate, excited-state computational simulations of the key low-lying excited states in these chromophores. Despite the strong fluorescence of these emitters, we observed a significant fraction of time-delayed (microseconds scale) emission associated with processes that involved passage through the triplet manifold. The accuracy of the predictions of the energy arrangement and electronic nature of the low-lying singlet and triplet excited states meant that an unambiguous assignment of the main deactivation pathways, including thermally activated delayed fluorescence and/or room temperature phosphorescence, was possible. The observation of triplet state formation indicates a breakthrough in the “classic” interpretation of the photophysical properties of the renowned BODIPY and its derivatives.This research was funded by Spanish Ministerio de Economia y Competitividad (project PID2020-114755GB-C31, C32 and C33) and Gobierno Vasco (IT1639-22)

The Mexican Patch-nosed Snake, Salvadora mexicana (Duméril, Bibron & Duméril, 1854; Squamata: Colubridae): a new state record for Zacatecas, Mexico, and a new prey species

Mexico, Zacatecas, Municipality of Valparaiso, ca. 2 km (airline) west of San Juan Capistrano, (22.637258° N; 104.118608° W [WGS84]; 1249 m elevation), 18 July 2017. Collected by Jorge A. Bañuelos-Alamillo. The snake was deposited in the Vertebrate Collection at Universidad Autónoma de Aguascalientes (CZUAA-REP-690); a photo voucher is also available at the San Diego Natural History Museum (SDSNH_HerpPC_05366). Adult female (SVL= 900 mm, TL= 380 mm), and had 17 midbody dorsal scales, 188 ventral scales, 106 subcaudals, nine supralabials, 11 infralabials, two loreal scales, one preocular, and three postoculars on both sides (Fig. 1-A). The snake was road-killed near a river within dry forest vegetation and had recently consumed an adult male Aspidoscelis gularis scalaris ingested headfirst.Asociación Herpetológica Argentin

The Mexican Patch-nosed Snake, Salvadora mexicana (Duméril, Bibron & Duméril, 1854; Squamata: Colubridae): a new state record for Zacatecas, Mexico, and a new prey species

Mexico, Zacatecas, Municipality of Valparaiso, ca. 2 km (airline) west of San Juan Capistrano, (22.637258° N; 104.118608° W [WGS84]; 1249 m elevation), 18 July 2017. Collected by Jorge A. Bañuelos-Alamillo. The snake was deposited in the Vertebrate Collection at Universidad Autónoma de Aguascalientes (CZUAA-REP-690); a photo voucher is also available at the San Diego Natural History Museum (SDSNH_HerpPC_05366). Adult female (SVL= 900 mm, TL= 380 mm), and had 17 midbody dorsal scales, 188 ventral scales, 106 subcaudals, nine supralabials, 11 infralabials, two loreal scales, one preocular, and three postoculars on both sides (Fig. 1-A). The snake was road-killed near a river within dry forest vegetation and had recently consumed an adult male Aspidoscelis gularis scalaris ingested headfirst.Asociación Herpetológica Argentin