Neuronal activity controls transsynaptic geometry

The neuronal synapse is comprised of several distinct zones, including presynaptic vesicle zone (SVZ), active zone (AZ) and postsynaptic density (PSD). While correct relative positioning of these zones is believed to be essential for synaptic function, the mechanisms controlling their mutual localization remain unexplored. Here, we employ high-throughput quantitative confocal imaging, super-resolution and electron microscopy to visualize organization of synaptic subdomains in hippocampal neurons. Silencing of neuronal activity leads to reversible reorganization of the synaptic geometry, resulting in a increased overlap between immunostained AZ and PSD markers; in contrast, the SVZ-AZ spatial coupling is decreased. Bayesian blinking and bleaching (3B) reconstruction reveals that the distance between the AZ-PSD distance is decreased by 30 nm, while electron microscopy shows that the width of the synaptic cleft is decreased by 1.1 nm. Our findings show that multiple aspects of synaptic geometry are dynamically controlled by neuronal activity and suggest mutual repositioning of synaptic components as a potential novel mechanism contributing to the homeostatic forms of synaptic plasticity

Bargaining to Achieve Teacher Control in Ontario

Les enseignants proclament depuis longtemps leur professionnalisme. Toutefois, ils n'ont pas de signes distinctifs propres aux professions traditionnelles et c'est pour cette raison qu'on ne leur a pas accorde un statut égal à leur professionnalisme. Les écrits traitant du professionnalisme suggèrent qu'obtenir le contrôle sur l'emploi ou obtenir le droit de participer aux prises de décision avant l'application d'une politique constituent des aspects majeurs si l'on souhaite atteindre le professionnalisme.Cette étude examine jusqu'à quel point les enseignants se sont servis des négociations collectives pour améliorer leur statut en participant aux prises de décision et, en particulier, en exerçant une autorité en milieu de travail.Les enseignants ont demandé longtemps une voix dans la politique scolaire, par l'intermédiaire de leurs fédérations. Ces demandes ont été rejetées par un refus évident de reconnaitre les caractéristiques professionnelles des enseignants comme, par exemple, leur compétence tant académique que pédagogique et leur désir de contrôler les prises de décision en matière d'éducation. Les enseignants ont donc été amenés à considérer la prise en main de l'emploi comme étant la première étape requise pour réconcilier leurs aspirations professionnelles avec la réalité de leur vie professionnelle.Cette étude considère le contrôle de l'emploi comme un aspect du professionnalisme.Les syndicats et autres organisations utilisent depuis longtemps les négociations collectives pour devenir maitres des secteurs ayant trait à leur vie professionnelle. Si les enseignants eux aussi sont décides à devenir maitres de leur emploi et en conséquence à devenir davantage professionnels, ils doivent aussi utiliser cette arme puissante. La Loi sur les négociations collectives entre Commissions scolaires et enseignants adoptée en 1975, a donné aux enseignants ontariens la possibilité d'utiliser les négociations collectives pour atteindre leurs objectifs. La loi (projet de loi 100) a formalisé le processus de négociation collective et a donne aux enseignants un moyen de participer aux prises de décision qui n'appartenaient auparavant qu'aux Commissions scolaires. Cette loi a elle-même joue un rôle majeur dans ce changement puisqu'elle a permis aux enseignants de négocier leurs termes et conditions d'emploi. L'usage que les enseignants ontariens ont fait des négociations collectives pour atteindre leur premier objectif, à savoir contrôler leur emploi, et leur objectif final, le professionnalisme, a servi de base pour l'analyse des résultats obtenus par eux dans les efforts qu'ils ont menée pour devenir maitres de leurs activités d'enseignant, après l'adoption de la loi 100. Cette étude analyse les résultats obtenus en dix ans par les enseignants ayant ravi, aux Commissions scolaires et à leurs administrateurs, le pouvoir décisionnel relatif à leur milieu de travail. Elle évalue l'efficacité du processus formel de négociation, établi en 1975, par rapport à celui utilise auparavant, qui était plus informel. Les données ont été recueillies à partir d'un échantillon de Commissions scolairesontariennes dont la population scolaire dépassait 2 000 étudiants, employant plus de 200 enseignants et ayant négocié des contrats entre 1970 et 1980. On a étudie le contenu de chaque contrat établi suite à des négociations collectives durant cette période afin de déterminer dans quelle mesure le contrôle de l'emploi était détenu par les enseignants plutôt que par la commission ou l'administration.Pour analyser la teneur du contrat, on a classifié le niveau de contrôle selon six catégories et quatre secteurs professionnels. Une analyse multivariée a servi à déterminer la variabilité des niveaux de contrôle que les enseignants ont atteint, en fonction des divers secteurs professionnels et des diverses Commissions scolaires. Les résultats montrent que les enseignants? Participent nettement plus aux prises de décision depuis l'adoption de la loi 100, le contrôle unilatéral que détenaient les Commissions scolaires ayant été remplace par un contrôle paritaire ou un processus de prise de décision mixte.Teachers' aspirations to professionalism are manifested in a desire to control educational decision-making. This research investigates success in achieving control of decision-making under formal bargaining, as defined by The School Boards andTeachers' Collective Negotiations Act, compared to non-formal bargainingused prior to 1975

On the Quantum Invariant for the Spherical Seifert Manifold

We study the Witten--Reshetikhin--Turaev SU(2) invariant for the Seifert manifold $S^3/\Gamma$ where $\Gamma$ is a finite subgroup of SU(2). We show that the WRT invariants can be written in terms of the Eichler integral of the modular forms with half-integral weight, and we give an exact asymptotic expansion of the invariants by use of the nearly modular property of the Eichler integral. We further discuss that those modular forms have a direct connection with the polyhedral group by showing that the invariant polynomials of modular forms satisfy the polyhedral equations associated to $\Gamma$.Comment: 36 page

Evaluation of environmental design strategies for university buildings

This paper examines the performance of environmental strategies in seven recently constructed or refurbished university buildings in the UK. These buildings contain a range of administrative spaces, classrooms, libraries and studios, reflecting their often complex, multi-use, heterogeneous nature. The key features of each environmental strategy are described (including passive, mixed-mode or active systems), in the context of the occupants and spaces they serve and the level of interaction that they afford. Energy performance and occupant thermal comfort (assessed by user surveys) are analysed and compared with studies of other non-domestic buildings, which have typically focused on more predictable single administrative uses (e.g. government offices), and unusually effective operation scenarios (e.g. continuous monitoring by expert building managers). The paper concludes by examining two of the case studies that reflect an increasingly common model of ‘flexible’ environmental design in more detail, identifying key features of the strategies for each building that have had a significant impact on their performance. The design assumptions leading to these features will be explored, and key lessons identified, contributing towards the development of a more robust evidential basis for choosing appropriate environmental strategies for university and other non-domestic buildings in the UK

Water vapour at high redshift: Arecibo monitoring of the megamaser in MG J0414+0534

The study of water masers at cosmological distances would allow us to investigate the parsec-scale environment around powerful radio sources, to probe the physical conditions of the molecular gas in the inner parsecs of quasars, and to estimate their nuclear engine masses in the early universe. To derive this information, the nature of the maser source, jet or disk-maser, needs to be assessed through a detailed investigation of the observational characteristics of the line emission. We monitored the maser line in the lensed quasar MGJ0414+0534 at z = 2.64 with the 300-m Arecibo telescope for ~15 months to detect possible additional maser components and to measure a potential velocity drift of the lines. In addition, we follow the maser and continuum emissions to reveal significant variations in their flux density and to determine correlation or time-lag, if any, between them. The main maser line profile is complex and can be resolved into a number of broad features with line widths of 30-160 km/s. A new maser component was tentatively detected in October 2008 that is redshifted by 470 km/s w.r.t the systemic velocity of the quasar. The line width of the main maser feature increased by a factor of two between the Effelsberg and EVLA observations reported by Impellizzeri et al. (2008) and the first epoch of the Arecibo monitoring campaign. After correcting for the lens magnification, we find that the total H2O isotropic luminosity of the maser in MGJ0414+0534 is now ~30,000 Lsun, making this source the most luminous ever discovered.[Abridged]Comment: 8 pages, 6 figures, accepted for publication in A&

Homogeneous photometry and star counts in the field of 9 Galactic star clusters

We present homogeneous $V,I$ CCD photometry of nine stellar fields in the two inner quadrants of the Galactic plane. The lines-of-view to most of these fields aim in the direction of the very inner Galaxy, where the Galactic field is very dense, and extinction is high and patchy. Our nine fields are, according to several catalogs, centred on Galactic star clusters, namely Trumpler 13, Trumpler 20, Lynga 4, Hogg 19, Lynga 12, Trumpler 25, Trumpler 26, Ruprecht 128, and Trumpler 34. Apart from their coordinates, and in some cases additional basic data (mainly from the 2MASS archive), their properties are poorly known. By means of star count techniques and field star decontaminated Color-Magnitude diagrams, the nature and size of these visual over-densities has been established; and, when possible, new cluster fundamental parameters have been derived. To strengthen our findings, we complement our data-set with JHK$_{s}$ photometry from the 2MASS archive, that we analyze using a suitably defined Q-parameter. Most clusters are projected towards the Carina-Sagittarium spiral arm. Because of that, we detect in the Color Magnitude Diagrams of most of the other fields several distinctive sequences produced by young population within the arm. All the clusters are of intermediate or old age. The most interesting cases detected by our study are, perhaps, that of Trumpler 20, which seems to be much older than previously believed, as indicated by its prominent -and double- red clump; and that of Hogg 19, a previously overlooked old open cluster, whose existence in such regions of the Milky Way is puzzling.Comment: 37 pages, 16 eps figures, in press in New Astronom

Entanglement can increase asymptotic rates of zero-error classical communication over classical channels

It is known that the number of different classical messages which can be communicated with a single use of a classical channel with zero probability of decoding error can sometimes be increased by using entanglement shared between sender and receiver. It has been an open question to determine whether entanglement can ever increase the zero-error communication rates achievable in the limit of many channel uses. In this paper we show, by explicit examples, that entanglement can indeed increase asymptotic zero-error capacity, even to the extent that it is equal to the normal capacity of the channel. Interestingly, our examples are based on the exceptional simple root systems E7 and E8.Comment: 14 pages, 2 figur

Another cluster of red supergiants close to RSGC1

Recent studies have revealed massive star clusters in a region of the Milky Way close to the tip of the Long Bar. These clusters are heavily obscured and are characterised by a population of red supergiants. We analyse a previously unreported concentration of bright red stars ~16' away from the cluster RSGC1. We utilised near IR photometry to identify candidate red supergiants and then K-band spectroscopy of a sample to characterise their properties. We find a compact clump of eight red supergiants and five other candidates at some distance, one of which is spectroscopically confirmed as a red supergiant. These objects must form an open cluster, which we name Alicante 8. Because of the high reddening and strong field contamination, the cluster sequence is not clearly seen in 2MASS or UKIDSS near-IR photometry. From the analysis of the red supergiants, we infer an extinction $A_{K_{{\rm S}}}=1.9$ and an age close to 20 Myr. Though this cluster is smaller than the three known previously, its properties still suggest a mass in excess of 10 000 M_{\sun}. Its discovery corroborates the hypothesis that star formation in this region has happened on a wide scale between ~10 and ~20 Myr ago.Comment: Accepted for publication in Astronomy & Astrophysics. Figure 1 degraded and changed to B&W, Figure 2 degraded to meet size requirement

Radio-optical scrutiny of compact AGN: Correlations between properties of pc-scale jets and optical nuclear emission

We study the correlations between the Very Long Baseline Array radio emission at 15 GHz, extended emission at 151 MHz, and optical nuclear emission at 5100 AA for a complete sample of 135 compact jets. We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical luminosities of host AGN. We find a significant positive correlation for 99 quasars between optical nuclear luminosities and total radio (VLBA) luminosities of unresolved cores at 15 GHz originated at milliarcseconds scales. For 18 BL Lacs, the optical continuum emission correlates with the radio emission of the jet at 15 GHz. We suggest that the radio and optical emission are beamed and originate in the innermost part of the sub--parsec-scale jet in quasars. Analysis of the relation between the apparent speed of the jet and the optical nuclear luminosity at 5100 AA supports the relativistic beaming model for the optical emission generated in the jet, and allows the peak values of the intrinsic optical luminosity of the jet and its Lorentz factor to be estimated for the populations of quasars, BL Lacs, and radio galaxies. The radio-loudness of quasars is found to increase at high redshifts, which can be a result of lower efficiency of the accretion in AGN having higher radio luminosities. A strong positive correlation is found between the intrinsic kinetic power of the jet and the apparent luminosities of the total and the unresolved core emission of the jet at 15 GHz. This correlation is interpreted in terms of intrinsically more luminous parsec-scale jet producing more luminous extended structure which is detectable at low radio frequencies, 151 MHz. A possibility that the low frequency radio emission is relativistically beamed in superluminal AGN and therefore correlates with radio luminosity of the jet at 15 GHz can not be ruled out (abridged).Comment: 16 pages, 10 figuers; minor comments are added; accepted to A&