A Spinal Opsin Controls Early Neural Activity and Drives a Behavioral Light Response

SummaryNonvisual detection of light by the vertebrate hypothalamus, pineal, and retina is known to govern seasonal and circadian behaviors [1]. However, the expression of opsins in multiple other brain structures [2–4] suggests a more expansive repertoire for light regulation of physiology, behavior, and development. Translucent zebrafish embryos express extraretinal opsins early on [5, 6], at a time when spontaneous activity in the developing CNS plays a role in neuronal maturation and circuit formation [7]. Though the presence of extraretinal opsins is well documented, the function of direct photoreception by the CNS remains largely unknown. Here, we show that early activity in the zebrafish spinal central pattern generator (CPG) and the earliest locomotory behavior are dramatically inhibited by physiological levels of environmental light. We find that the photosensitivity of this circuit is conferred by vertebrate ancient long opsin A (VALopA), which we show to be a Gαi-coupled receptor that is expressed in the neurons of the spinal network. Sustained photoactivation of VALopA not only suppresses spontaneous activity but also alters the maturation of time-locked correlated network patterns. These results uncover a novel role for nonvisual opsins and a mechanism for environmental regulation of spontaneous motor behavior and neural activity in a circuit previously thought to be governed only by intrinsic developmental programs

Classification and Moduli Kahler Potentials of G_2 Manifolds

Compact manifolds of G_2 holonomy may be constructed by dividing a seven-torus by some discrete symmetry group and then blowing up the singularities of the resulting orbifold. We classify possible group elements that may be used in this construction and use this classification to find a set of possible orbifold groups. We then derive the moduli Kahler potential for M-theory on the resulting class of G_2 manifolds with blown up co-dimension four singularities.Comment: 30 pages, Latex, references adde

Triplanar Model for the Gap and Penetration Depth in YBCO

YBaCuO_7 is a trilayer material with a unit cell consisting of a CuO_2 bilayer with a CuO plane of chains in between. Starting with a model of isolated planes coupled through a transverse matrix element, we consider the possibility of intra as well as interplane pairing within a nearly antiferromagnetic Fermi liquid model. Solutions of a set of three coupled BCS equations for the gap exhibit orthorhombic symmetry with s- as well as d-wave contributions. The temperature dependence and a-b in plane anisotropy of the resulting penetration depth is discussed and compared with experiment.Comment: To appear in Physical Review B1 01Mar97; 12 pages with 10 figures; RevTeX+eps

Regularisation Techniques for the Radiative Corrections of Wilson lines and Kaluza-Klein states

Within an effective field theory framework we compute the most general structure of the one-loop corrections to the 4D gauge couplings in one- and two-dimensional orbifold compactifications with non-vanishing constant gauge background (Wilson lines). Although such models are non-renormalisable, we keep the analysis general by considering the one-loop corrections in three regularisation schemes: dimensional regularisation (DR), Zeta-function regularisation (ZR) and proper-time cut-off regularisation (PT). The relations among the results obtained in these schemes are carefully addressed. With minimal re-definitions of the parameters involved, the results obtained for the radiative corrections can be applied to most orbifold compactifications with one or two compact dimensions. The link with string theory is discussed. We mention a possible implication for the gauge couplings unification in such models.Comment: 37 pages, 1 Figure, LaTeX; minor correction

Birmingham’s Eastside story: making steps towards sustainability?

Sustainability has come to play a dominant discursive role in the UK planning system, particularly relating to urban regeneration. The purpose of this paper is to evaluate the role that sustainability plays in a major regeneration programme, known as Eastside, currently underway in Birmingham, the UK. That this £6 billion redevelopment is now widely talked about by such key players as Birmingham City Council and the Regional Development Agency, Advantage West Midlands, as having a central sustainability agenda points to the growing importance of the ideal of sustainability in planning and regeneration agendas. In this paper, we investigate in detail how and why sustainability has become part of the planning discourse for Eastside and critically evaluate what impact, if any, this is having on public policy decision-making

Do rural migrants 'float' in urban China? Neighbouring and neighbourhood sentiment in Beijing

Urban China reached 50% of the nation’s population by 2010, mainly as a result of massive rural–urban migration. There is substantial evidence of their social marginality in terms of occupational and housing opportunities. Here we ask about their incorporation into the neighbourhoods where they live. Rural migrants are called the ‘floating population’ in China, suggesting that their residence in the city is only temporary and that they are unlikely to develop strong local ties. This study contrasts the neighbourhood socialising of migrant tenants with that of urban homeowners who were born in the city. It draws on original survey research in Beijing that included questions on relations with neighbours and neighbourhood sentiment. It is found that migrants are more likely to engage in socialising and exchange of help with neighbours, and consequently their neighbouring helps strengthen their sentiment towards the neighbourhoods where they live. It is argued that contemporary social changes – including rising education and homeownership – may actually reduce neighbouring, while rural migrants’ marginality makes them more dependent on their local social network

Seeking Evolution of Dark Energy

We study how observationally to distinguish between a cosmological constant (CC) and an evolving dark energy with equation of state $\omega(Z)$. We focus on the value of redshift Z* at which the cosmic late time acceleration begins and $\ddot{a}(Z^{*}) = 0$. Four $\omega(Z)$ are studied, including the well-known CPL model and a new model that has advantages when describing the entire expansion era. If dark energy is represented by a CC model with $\omega \equiv -1$, the present ranges for $\Omega_{\Lambda}(t_0)$ and $\Omega_m(t_0)$ imply that Z* = 0.743 with 4% error. We discuss the possible implications of a model independent measurement of Z* with better accuracy.Comment: 9 pages, LaTeX, 5 figure

Orbifold Singularities, Lie Algebras of the Third Kind (LATKes), and Pure Yang-Mills with Matter

We discover the unique, simple Lie Algebra of the Third Kind, or LATKe, that stems from codimension 6 orbifold singularities and gives rise to a kind of Yang-Mills theory which simultaneously is pure and contains matter. The root space of the LATKe is 1-dimensional and its Dynkin diagram consists of one point. The uniqueness of the LATKe is a vacuum selection mechanism.Comment: 42 pages; version appearing in JM