Dipòsit i caracterització de capes primes orgàniques de P3HT:PCBM per a aplicacions fotovoltaiques

En un món on el ritme de la societat actual ens ha portat a considerar les energies enovables com a prioritat vital i necessària i en el que es preveu que la demanda energètica augmenti un 50% fins al 2030, l'interès en la recerca de materials emiconductors orgànics per aplicacions de captura solar, ha assolit un potencial enorme de cara al futur. Molts són el avantatges que presenten aquest tipus de materials en front als seus homòlegs inorgànics. La facilitat de fabricació, la utilització de materials més econòmics i amb menys impacte ambiental, així com la possibilitat de produir dispositius flexibles, són algunes de les atractives aracterístiques que presenten aquests materials. No obstant, certs inconvenients om les baixes eficiències energètiques dels dispositius, i la inestabilitat ambiental ue es tradueix en un temps de vida molt reduït, fan que encara s'hagi d'invertir sforç per aconseguir que aquests materials puguin ser utilitzats en el camp de la aptura d'energia solar. El material més prometedor fins a data d'avui és el P3HT:PCBM. Es tracta d'un sistema polímer:molècula lleugera, on el P3HT actua com a component donador del sistema i el PCBM actua com a component acceptor. Les propietats optoelectròniques i eficiències energètiques de combinats orgànics P3HT:PCBM epèn en gran mesura de la seva morfologia i microestructura. Paràmetres com la proporció entre els components, el dissolvent utilitzat en la dissolució, així com 'aplicació de determinats tractaments tèrmics afecten de forma crítica a la seva orfologia. Durant el present treball s'han utilitzat diverses tècniques de caracterització per a estudiar determinades propietats que presenten aquest tipus de aterials. Entre les tècniques experimentals utilitzades hi trobem la microscòpia FM, l'espectroscòpia Raman i la conductimetria AFM o current sensing AFM CS-AFM). Els experiments en temps real durant l'escalfament de capes primes 3HT:PCBM, mostren que el P3HT pateix una cristal·lització al voltant dels 140ºC, permetent el reordenament de les molècules i un millor solapament del sorbitals [pi]-[pi]*, que resulta en un increment del transport de forats a través de la fase donadora del material. Paralel·lament, entre els 80-120ºC, el material també presenta determinats canvis tant en el comportament dels enllaços, com en la cristal·linitat del material, provocant una quasi transició de fase que atribuïm a la transició vitrea del material. Per altra banda, experiments amb conductimetria AFM realitzats en sistemes P3HT:HDPE mostren un signicatiu augment en la eva estabilitat ambiental, que es tradueix en un augment del temps de vida, sense una pèrdua considerable en els seus valors de conducció. Tot i la combinació del P3HT amb proporcions de polímers aïllants de fins al 80%, el sistema és capaç de no perdre la capacitat de transport gràcies a la formació de fases i dominis rics en P3HT. El present treball posa de manifest que ens trobem davant d'una tecnologia emergent i que nous estudis i esforços en la recerca d'aquest tipus materials és fonamental per aconseguir nous resultats i posicionar als materials semiconductors orgànics com una alternativa viable en el camp dels dispositus fotovoltaics. Assumint dades procedents de la tecnologia actual utilitzada en aquest tipus de materials, estudis i avaluacions ambientals i econòmiques mostren que petits increments tant en les eficiències com en el temps de vida de dispositius basats en aterials orgànics, posicionarien a aquest material com a alternativa totalment viable en el mercat fotovoltaic d'un futur proper.

Avaluació del creixement del fong ligninolític Trametes versicolor sobre diferents suports sòlids per a l'aplicació en tractaments de bioremediació

Els fongs de podridura blanca (WRF - de l'anglès: White-rot fungi) són de gran interès en l'àmbit de la bioremediació per la seva capacitat de degradar la lignina. La lacasa, un dels enzims extracel·lulars que aquests fongs excreten per degradar la lignina, pot ser utilitzada per degradar els contamiants presents en una matriu donada. Trametes versicolor ha estat estudiat per la seva capacitat de produïr aquest enzim en rersidus agrícoles com a substrats. Un primer triatge basat en la producció de CO2, la mesura de l'activitat lacasa i la quantificació de l'ergosterol han permés seleccionar els substrats on es donava un major poder oxidatiu dels cultius inoculats amb T. versicolor. Els posteriors experiments de colonització de sòls, on es monitoritzava l'activitat lacasa i l'ergosterol, han mostrat que T. vesicolor és capaç de colonitzar sòls i que té una major activitat lacasa en condicions no estèrils. També h'ha provat, mitjançant el test ND24, que T. versicolor és capaç de degradar un contaminant emergent, el naproxè, en sòls estèrils i no estèrils esmenats amb residus agrícoles.

Report of Diabetes Review Steering Group

DHSSPS has published the findings of the Report of the Steering Group chaired by the Chief Medical officer examining services for people with diabetes. The report assesses progress against the objectives of the original CREST/Diabetes UK Joint Taskforce Report (2003). åÊThere is an overview of the epidemiology of the condition as well as an assessment of current service provision, identified gaps and emergent priorities.

A review of the ticks (Acari, Ixodida) of Brazil, their hosts and geographic distribution - 1. The State of Rio Grande do Sul, Southern Brazil

A review of the ticks (Acari, Ixodida) of the State of Rio Grande do Sul, southern Brazil, was completed as a step towards a definitive list (currently indicated as 12) of such species, their hosts and distribution. The ticks: Argas miniatus (poultry), Ixodes loricatus (opossums), Amblyomma aureolatum (dogs), A. calcaratum (anteaters), A. cooperi (capybaras), A. nodosum (anteaters), A. tigrinum (dogs) (Neotropical) and Rhipicephalus sanguineus (dogs) (introduced, cosmopolitan, Afrotropical) were confirmed as present, in addition to the predominant, Boophilus microplus (cattle) (introduced, pan-tropical, Oriental). Of the further 18 species thus far reported in the literature as present in the state, but unavailable for examination: only Ornithodoros brasiliensis (humans and their habitations) (Neotropical), Ixodes affinis (deer) (Nearctic/Neotropical) and I. auritulus (birds) (Nearctic/Neotropical/Afrotropical/ Australasian) are considered likely; 13 species would benefit from corroborative local data but the majority appear unlikely; reports of A. maculatum (Nearctic/Neotropical, but circum-Caribbean) are considered erroneous; the validity of A. fuscum is in doubt. The very recent, first known report of the tropical Anocentor nitens (horses)(Nearctic/Neotropical), but still apparent absence of the tropical A. cajennense (catholic) (Nearctic/Neotropical) and the sub-tropical/temperate Ixodes pararicinus (cattle) (Neotropical) in Rio Grande do Sul are important for considerations on their current biogeographical distribution and its dynamics in South America. The state has relatively long established, introduced ("exotic"), Old World tick species (B. microplus, R. sanguineus) that continue to represent significant pests and disease vectors to their traditional, introduced domestic animal hosts, cattle and urban dogs. There are also indigenous, New World ticks (A. miniatus, O. brasiliensis, A. aureolatum, A. nitens), as both long established and possibly newly locally introduced species in the state, that should be considered as potential and emergent pests and pathogen vectors to humans and their more recently acquired, introduced domestic animal hosts; rural poultry, dogs and horses.

Orthogonal organic and aqueous-based washes of tissue sections to enhance protein sensitivity by MALDI imaging mass spectrometry.

Imaging mass spectrometry (IMS) is an emergent and innovative approach for measuring the composition, abundance and regioselectivity of molecules within an investigated area of fixed dimension. Although providing unprecedented molecular information compared with conventional MS techniques, enhancement of protein signature by IMS is still necessary and challenging. This paper demonstrates the combination of conventional organic washes with an optimized aqueous-based buffer for tissue section preparation before matrix-assisted laser desorption/ionization (MALDI) IMS of proteins. Based on a 500 mM ammonium formate in water-acetonitrile (9:1; v/v, 0.1% trifluororacetic acid, 0.1% Triton) solution, this buffer wash has shown to significantly enhance protein signature by profiling and IMS (~fourfold) when used after organic washes (70% EtOH followed by 90% EtOH), improving the quality and number of ion images obtained from mouse kidney and a 14-day mouse fetus whole-body tissue sections, while maintaining a similar reproducibility with conventional tissue rinsing. Even if some protein losses were observed, the data mining has demonstrated that it was primarily low abundant signals and that the number of new peaks found is greater with the described procedure. The proposed buffer has thus demonstrated to be of high efficiency for tissue section preparation providing novel and complementary information for direct on-tissue MALDI analysis compared with solely conventional organic rinsing.

Anàlisi i abordatge de l’assetjament entre iguals mitjançant l’ús de les noves tecnologies

L’estudi analitza la modalitat d’assetjament entre iguals mitjançant la utilització de les TIC, un fenomen emergent en el marc de la justícia juvenil a Catalunya. S’han revisat 185 expedients de menors dels que la Fiscalia de Menors ha oficiat per requerir la intervenció de l’equip tècnic. Els principals resultats obtinguts ens mostren una incidència baixa (10,9%), però l’ús generalitzat d’aquests dispositius tecnològics exposen els menors a uns riscos elevats i l’impacte en les víctimes, properes en el seu entorn, suposa una afectació emocional i psicosocial greu. Alhora, hem vist la relació d’aquest tipus de comportaments amb altres formes de violència exercida pels mateixos protagonistes. Les conductes del victimari, nascut a Catalunya en un 73% dels casos, es donen majoritàriament en grup i en els primers anys de l’adolescència mitjana. Es troba una relació entre el tipus d’assetjament tradicional tipificat fins ara com a delictes contra la integritat i la llibertat personal protagonitzats per nois (58,9%) i la durada del delicte, inferior a un mes. Les víctimes són noies en major proporció (56%), però, a la vegada, prenen rellevància en l’autoria d’aquest tipus d’accions en relació amb la incidència que tenen altres actuacions delictives que protagonitzen. És reveladora la força de les xarxes socials en aquests tipus de fets i la necessitat de prevenció, de protecció i d’educació en les competències d’aquest ús d’aplicacions i dispositius en l’espai virtual. Es proposa que la intervenció dels professionals de justícia juvenil consisteixi en la conscienciació, la responsabilització d’aquestes conductes, tot adequant continguts dels programes tècnics i evitant, sempre que sigui possible, l’entrada al circuit judicial.

Eliminació autotròfica de nitrogen en una pila biològica (microbial fuel cells )

L’aigua i l’energia formen un binomi indissociable. En relació al cicle de l’aigua, des de fa varies dècades s’han desenvolupat diferents formes per recuperar part de l’energia relacionada amb l’aigua, per exemple a partir de centrals hidroelèctriques. No obstant, l’ús d’aquesta aigua també porta associat un gran consum energètic, relacionat sobretot amb el transport, la distribució, la depuració, etc... La depuració d’aigües residuals porta associada una elevada demanda energètica (Obis et al.,2009). En termes energètics, tot i que la despesa elèctrica d’una EDAR varia en funció de diferents paràmetres com la configuració i la capacitat de la planta, la càrrega a tractar, etc... es podria considerar que el rati mig seria d’ aproximadament 0.5 KWh•m-3.Els principals costos d’explotació estan relacionats tant amb la gestió de fangs (28%) com amb el consum elèctric (25%) (50% tractament biològic). Tot i que moltes investigacions relacionades amb el tractament d’aigua residual estan encaminades en disminuir els costos d’operació, des de fa poques dècades s’està investigant la viabilitat de que l’aigua residual fins i tot sigui una font d’energia, canviant la perspectiva, i començant a veure l’aigua residual no com a una problemàtica sinó com a un recurs. Concretament s’estima que l’aigua domèstica conté 9.3 vegades més energia que la necessària per el seu tractament mitjançant processos aerobis (Shizas et al., 2004). Un dels processos més desenvolupats relacionats amb el tractament d’aigües residuals i la producció energètica és la digestió anaeròbia. No obstant, aquesta tecnologia permet el tractament d’altes càrregues de matèria orgànica generant un efluent ric en nitrogen que s’haurà de tractar amb altres tecnologies. Per altre banda, recentment s’està investigant una nova tecnologia relacionada amb el tractament d’aigües residuals i la producció energètica: les piles biològiques (microbial fuel cells, MFC). Aquesta tecnologia permet obtenir directament energia elèctrica a partir de la degradació de substrats biodegradables (Rabaey et al., 2005). Les piles biològiques, més conegudes com a Microbial Fuel Cells (acrònim en anglès, MFC), són una emergent tecnologia que està centrant moltes mirades en el camp de l’ investigació, i que es basa en la producció d’energia elèctrica a partir de substrats biodegradables presents en l’aigua residual (Logan., 2008). Els fonaments de les piles biològiques és molt semblant al funcionament d’una pila Daniell, en la qual es separa en dos compartiments la reacció d’oxidació (compartiment anòdic) i la de reducció (compartiment catòdic) amb l’objectiu de generar un determinat corrent elèctric. En aquest estudi, bàsicament es mostra la posada en marxa d'una pila biològica per a l'eliminació de matèria orgànica i nitrogen de les aigües residuals.

Schistosomiasis mansoni in areas of low transmission: epidemiological characterization of Venezuelan foci

Severe schistosomiasis is a rare event in Venezuela nowadays, after a successful national campaign by the Schistosomiasis Control Program. Unfortunately, this program has practically disappeared, and snail surveillance in field is not a priority, anymore. Thus, schistosomiasis has become a neglected disease in this country. However, surveys in different populations from the endemic area have shown particular epidemiological features described herein. In five communities we evaluated 2,175 persons and searched for the presence of Biomphalaria glabrata snails. Some markers were used for classifying schistosomiasis foci: mean age of the persons with Schistosoma mansoni eggs in the stools, serological tests, presence of B. glabrata snails, and intensity of infection. Places without B. glabrata snails and with few schistosomiasis cases were defined as "past transmission sites"; a site with abundant snails but few cases was defined as "potential risk"; "new transmission" foci were characterized by the presence of infected snails and young people passing eggs in the stools. A "re-emergent" focus has shared these last features, showing in addition a place where schistosomiasis had been reported before. Recent evidences of active transmission with the increasing dispersion of B. glabrata snails, point out the necessity for the re-establishment of the Schistosomiasis Control Program in Venezuela.

Policy Diffusion: An Agent-Based Approach

Methods like Event History Analysis can show the existence of diffusion and part of its nature, but do not study the process itself. Nowadays, thanks to the increasing performance of computers, processes can be studied using computational modeling. This thesis presents an agent-based model of policy diffusion mainly inspired from the model developed by Braun and Gilardi (2006). I first start by developing a theoretical framework of policy diffusion that presents the main internal drivers of policy diffusion - such as the preference for the policy, the effectiveness of the policy, the institutional constraints, and the ideology - and its main mechanisms, namely learning, competition, emulation, and coercion. Therefore diffusion, expressed by these interdependencies, is a complex process that needs to be studied with computational agent-based modeling. In a second step, computational agent-based modeling is defined along with its most significant concepts: complexity and emergence. Using computational agent-based modeling implies the development of an algorithm and its programming. When this latter has been developed, we let the different agents interact. Consequently, a phenomenon of diffusion, derived from learning, emerges, meaning that the choice made by an agent is conditional to that made by its neighbors. As a result, learning follows an inverted S-curve, which leads to partial convergence - global divergence and local convergence - that triggers the emergence of political clusters; i.e. the creation of regions with the same policy. Furthermore, the average effectiveness in this computational world tends to follow a J-shaped curve, meaning that not only time is needed for a policy to deploy its effects, but that it also takes time for a country to find the best-suited policy. To conclude, diffusion is an emergent phenomenon from complex interactions and its outcomes as ensued from my model are in line with the theoretical expectations and the empirical evidence.Les méthodes d'analyse de biographie (event history analysis) permettent de mettre en évidence l'existence de phénomènes de diffusion et de les décrire, mais ne permettent pas d'en étudier le processus. Les simulations informatiques, grâce aux performances croissantes des ordinateurs, rendent possible l'étude des processus en tant que tels. Cette thèse, basée sur le modèle théorique développé par Braun et Gilardi (2006), présente une simulation centrée sur les agents des phénomènes de diffusion des politiques. Le point de départ de ce travail met en lumière, au niveau théorique, les principaux facteurs de changement internes à un pays : la préférence pour une politique donnée, l'efficacité de cette dernière, les contraintes institutionnelles, l'idéologie, et les principaux mécanismes de diffusion que sont l'apprentissage, la compétition, l'émulation et la coercition. La diffusion, définie par l'interdépendance des différents acteurs, est un système complexe dont l'étude est rendue possible par les simulations centrées sur les agents. Au niveau méthodologique, nous présenterons également les principaux concepts sous-jacents aux simulations, notamment la complexité et l'émergence. De plus, l'utilisation de simulations informatiques implique le développement d'un algorithme et sa programmation. Cette dernière réalisée, les agents peuvent interagir, avec comme résultat l'émergence d'un phénomène de diffusion, dérivé de l'apprentissage, où le choix d'un agent dépend en grande partie de ceux faits par ses voisins. De plus, ce phénomène suit une courbe en S caractéristique, poussant à la création de régions politiquement identiques, mais divergentes au niveau globale. Enfin, l'efficacité moyenne, dans ce monde simulé, suit une courbe en J, ce qui signifie qu'il faut du temps, non seulement pour que la politique montre ses effets, mais également pour qu'un pays introduise la politique la plus efficace. En conclusion, la diffusion est un phénomène émergent résultant d'interactions complexes dont les résultats du processus tel que développé dans ce modèle correspondent tant aux attentes théoriques qu'aux résultats pratiques.

Aganirsen Antisense Oligonucleotide Eye Drops Inhibit Keratitis-Induced Corneal Neovascularization and Reduce Need for Transplantation: The I-CAN Study.

OBJECTIVE: Eye drops of aganirsen, an antisense oligonucleotide preventing insulin receptor substrate-1 expression, inhibited corneal neovascularization in a previous dose-finding phase II study. We aimed to confirm these results in a phase III study and investigated a potential clinical benefit on visual acuity (VA), quality of life (QoL), and need for transplantation. DESIGN: Multicenter, double-masked, randomized, placebo-controlled phase III study. PARTICIPANTS: Analysis of 69 patients with keratitis-related progressive corneal neovascularization randomized to aganirsen (34 patients) or placebo (35 patients). Patients applied aganirsen eye drops (86 μg/day/eye) or placebo twice daily for 90 days and were followed up to day 180. MAIN OUTCOME MEASURES: The primary end point was VA. Secondary end points included area of pathologic corneal neovascularization, need for transplantation, risk of graft rejection, and QoL. RESULTS: Although no significant differences in VA scores between groups were observed, aganirsen significantly reduced the relative corneal neovascularization area after 90 days by 26.20% (P = 0.014). This improvement persisted after 180 days (26.67%, P = 0.012). Aganirsen tended to lower the transplantation need in the intent-to-treat (ITT) population at day 180 (P = 0.087). In patients with viral keratitis and central neovascularization, a significant reduction in transplantation need was achieved (P = 0.048). No significant differences between groups were observed in the risk of graft rejection. However, aganirsen tended to decrease this risk in patients with traumatic/viral keratitis (P = 0.162) at day 90. The QoL analyses revealed a significant improvement with aganirsen in composite and near activity subscores (P = 0.039 and 0.026, respectively) at day 90 in the per protocol population. Ocular and treatment-related treatment-emergent adverse events (TEAEs) were reported in a lower percentage with aganirsen compared with placebo. Only 3 serious TEAEs (2 with aganirsen and 1 with placebo) were considered treatment-related. CONCLUSIONS: This first phase III study on a topical inhibitor of corneal angiogenesis showed that aganirsen eye drops significantly inhibited corneal neovascularization in patients with keratitis. The need for transplantation was significantly reduced in patients with viral keratitis and central neovascularization. Topical application of aganirsen was safe and well tolerated.

How local excitation-inhibition ratio impacts the whole brain dynamics.

The spontaneous activity of the brain shows different features at different scales. On one hand, neuroimaging studies show that long-range correlations are highly structured in spatiotemporal patterns, known as resting-state networks, on the other hand, neurophysiological reports show that short-range correlations between neighboring neurons are low, despite a large amount of shared presynaptic inputs. Different dynamical mechanisms of local decorrelation have been proposed, among which is feedback inhibition. Here, we investigated the effect of locally regulating the feedback inhibition on the global dynamics of a large-scale brain model, in which the long-range connections are given by diffusion imaging data of human subjects. We used simulations and analytical methods to show that locally constraining the feedback inhibition to compensate for the excess of long-range excitatory connectivity, to preserve the asynchronous state, crucially changes the characteristics of the emergent resting and evoked activity. First, it significantly improves the model's prediction of the empirical human functional connectivity. Second, relaxing this constraint leads to an unrealistic network evoked activity, with systematic coactivation of cortical areas which are components of the default-mode network, whereas regulation of feedback inhibition prevents this. Finally, information theoretic analysis shows that regulation of the local feedback inhibition increases both the entropy and the Fisher information of the network evoked responses. Hence, it enhances the information capacity and the discrimination accuracy of the global network. In conclusion, the local excitation-inhibition ratio impacts the structure of the spontaneous activity and the information transmission at the large-scale brain level.

Accepting Methadone: The Evolution of an Institutional Decision

This is a study of organisational decision making among senior civil servants in the Department of Health (DOH) in relation to the acceptance of methadone maintenance as a valid treatment modality for opiate misuse in Ireland. A qualitative strategy was adopted with an emergent design and grounded theory perspective. The data was collected using a naturalistic mode of inquiry and comprised of documentary analysis and semi-structured interviews. The aspects of decision making chosen for the study were: 1. Identifying the actors involved considering the heretofore dominant 'corporation sole' culture of the Irish public administration. 2. Identifying two (out of the myriad) processes involved in decision making. 3. Identifying what theoretical model(s) of decision making most closely approximates to this case. The findings were as follows: 1. Actors involved at all levels of the decision making could be identified, albeit with some difficulty. This as a result of the strategic management initiative. Previously, it may not have been possible. Stages or phases could not, in this case, be readily identified though limitations of this study may prove significant. 2. Both the processes selected in decision-making in this case were confirmed. Personal and professional support provided by peers and seniors is crucial to decision making. Decision making does occur within networks: these tend to be those that are formally appointed rather than informal ones. 3. The model closest to that of this case was that of incremental decision making within network settings.This resource was contributed by The National Documentation Centre on Drug Use.

Schizophrenic delusions: a phenomenological approach.

The issue of specificity of delusions in schizophrenia is still a matter of debate. The authors analyze the delusion formation in schizophrenia from a prototypical, phenomenological point of view, focusing on the subject's experience. This perspective links delusion formation to the autistic predisposition, which is considered here as the elementary phenotypic expression of the vulnerability to schizophrenia. Autism is viewed as a defective preconceptual (i.e., before language) attunement to the world. It impedes the individual's sharing of "common sense" with others and impairs the ability to project into the future. The development of delusions is illustrated, in part, by Klaus Conrad's work on the onset of paranoid schizophrenia. Delusions are viewed as transformations of the structure of experiencing. When threatened in future ability to be, the autistic, vulnerable person looks for the clues to becoming by attributing significance to disparate elements of the environment, which become self-referential. The link established between these disparate elements is based on universal characteristics that give the schizophrenic delusion a metaphysical quality. The transitivistic experience in delusions of control and omnipotence points to a specific way of crossing the border between "mine" and "yours" (disturbances of the experiencing "I"). What strikes a clinician in these delusions is that the normally tacit link between the sense of being and the sense of acting becomes quite apparent. The authors also propose a specificity in the themes of schizophrenic delusions. Delusions acquire a schizophrenic quality when ontological (i.e., universal) elements of the discourse between the locutor and the Other dominate at the expense of the worldly elements. It is emphasized that delusional content and form are dialectically related and hardly distinguishable. The authors consider the delusion formation as a phenomenon of emergence, a situation in which a new qualitative order arises from the reorganization of essentially unchanged elements. To consider schizophrenia as an emergent, particular way of experiencing, related to the autistic defect, has important consequences for research and for treatment. A dialectic exchange is needed between prototypical models generated by phenomenological inquiry and empirical, operational validation of testable aspects of such models.

Quantifying network properties in multi-electrode recordings: spatiotemporal characterization and inter-trial variation of evoked gamma oscillations in mouse somatosensory cortex in vitro.

Linking the structural connectivity of brain circuits to their cooperative dynamics and emergent functions is a central aim of neuroscience research. Graph theory has recently been applied to study the structure-function relationship of networks, where dynamical similarity of different nodes has been turned into a "static" functional connection. However, the capability of the brain to adapt, learn and process external stimuli requires a constant dynamical functional rewiring between circuitries and cell assemblies. Hence, we must capture the changes of network functional connectivity over time. Multi-electrode array data present a unique challenge within this framework. We study the dynamics of gamma oscillations in acute slices of the somatosensory cortex from juvenile mice recorded by planar multi-electrode arrays. Bursts of gamma oscillatory activity lasting a few hundred milliseconds could be initiated only by brief trains of electrical stimulations applied at the deepest cortical layers and simultaneously delivered at multiple locations. Local field potentials were used to study the spatio-temporal properties and the instantaneous synchronization profile of the gamma oscillatory activity, combined with current source density (CSD) analysis. Pair-wise differences in the oscillation phase were used to determine the presence of instantaneous synchronization between the different sites of the circuitry during the oscillatory period. Despite variation in the duration of the oscillatory response over successive trials, they showed a constant average power, suggesting that the rate of expenditure of energy during the gamma bursts is consistent across repeated stimulations. Within each gamma burst, the functional connectivity map reflected the columnar organization of the neocortex. Over successive trials, an apparently random rearrangement of the functional connectivity was observed, with a more stable columnar than horizontal organization. This work reveals new features of evoked gamma oscillations in developing cortex.

Biological embedding of early life exposures and disease risk in humans: a role for DNA methylation.

BACKGROUND: Following wider acceptance of "the thrifty phenotype" hypothesis and the convincing evidence that early life exposures can influence adult health even decades after the exposure, much interest has been placed on the mechanisms through which early life exposures become biologically embedded. METHODS: In this review, we summarize the current literature regarding biological embedding of early life experiences. To this end we conducted a literature search to identify studies investigating early life exposures in relation to DNA methylation changes. In addition, we summarize the challenges faced in investigations of epigenetic effects, stemming from the peculiarities of this emergent and complex field. A proper systematic review and meta-analyses were not feasible given the nature of the evidence. RESULTS: We identified 7 studies on early life socioeconomic circumstances, 10 studies on childhood obesity, and 6 studies on early life nutrition all relating to DNA methylation changes that met the stipulated inclusion criteria. The pool of evidence gathered, albeit small, favours a role of epigenetics and DNA methylation in biological embedding, but replication of findings, multiple comparison corrections, publication bias, and causality are concerns remaining to be addressed in future investigations. CONCLUSIONS: Based on these results, we hypothesize that epigenetics, in particular DNA methylation, is a plausible mechanism through which early life exposures are biologically embedded. This review describes the current status of the field and acts as a stepping stone for future, better designed investigations on how early life exposures might become biologically embedded through epigenetic effects. This article is protected by copyright. All rights reserved.