The landscape history of Godmanchester (Quebec, Canada): two centuries of shifting relationships between anthropic and biophysical factors

Abstract Taking into consideration ecological aspects in land management requires an understanding of the processes and dynamics that create landscapes. To achieve this understanding demands that landscapes be studied as a biophysical and social reality, and that phenomena be analyzed within a historical perspective. Based on the research of a multidisciplinary team over the last 25 years, this paper proposes to reconstitute the landscape of Godmanchester (Quebec, Canada) from the precolonial period (1785) to today (2005). Using various methods and sources of data, seven stages of evolution were identified: (1) the pre-colonial period, (2) the first settlements, (3) the first agricultural developments, (4) the maximum development of agricultural activities, (5) the concentration of agricultural activities, (6) the intensification of agricultural activities, and (7) the importance of new amenities. First, these results allowed us to identify three sets of fundamental factors that are necessary to understanding the landscape changes, the geomorphological characteristics, the socio-economic demands, and the technological transformations. Second, the results highlight the key elements and the perspectives that are appropriate to their comprehension, in order to be able to direct the future evolution of the landscapes. This requires that transformations be analyzed from mid-term to longterm perspectives, that the consequences of the changes, as well as the opportunities that they generate, are well understood, and finally that relationships be drawn between the biophysical, anthropic, and technological factors responsible for these transformations. This paper concludes with the idea that the creation of landscapes occurs through actions brought about by social demands and by the adjustment of technologies according to the biophysical characteristics of the territories

Heterotic T-folds with a small number of neutral moduli

We discuss non-geometric supersymmetric heterotic string models in D=4, in the framework of the free fermionic construction. We perform a systematic scan of models with four a priori left-right asymmetric Z_2 projections and shifts. We analyze some 2^{20} models, identifying 18 inequivalent classes and addressing variants generated by discrete torsions. They do not contain geometrical or trivial neutral moduli, apart from the dilaton. However, we show the existence of flat directions in the form of exactly marginal deformations and identify patterns of symmetry breaking where product gauge groups, realized at level one, are broken to their diagonal at higher level. We also describe an "inverse Gepner map" from Heterotic to Type II models that could be used, in certain non geometric settings, to define "effective" topological invariants.Comment: 37 page

The Conformal Sector of F-theory GUTs

D3-brane probes of exceptional Yukawa points in F-theory GUTs are natural hidden sectors for particle phenomenology. We find that coupling the probe to the MSSM yields a new class of N = 1 conformal fixed points with computable infrared R-charges. Quite surprisingly, we find that the MSSM only weakly mixes with the strongly coupled sector in the sense that the MSSM fields pick up small exactly computable anomalous dimensions. Additionally, we find that although the states of the probe sector transform as complete GUT multiplets, their coupling to Standard Model fields leads to a calculable threshold correction to the running of the visible sector gauge couplings which improves precision unification. We also briefly consider scenarios in which SUSY is broken in the hidden sector. This leads to a gauge mediated spectrum for the gauginos and first two superpartner generations, with additional contributions to the third generation superpartners and Higgs sector.Comment: v2: 51 pages, 2 figures, remark added, typos correcte

Quiver Structure of Heterotic Moduli

We analyse the vector bundle moduli arising from generic heterotic compactifications from the point of view of quiver representations. Phenomena such as stability walls, crossing between chambers of supersymmetry, splitting of non-Abelian bundles and dynamic generation of D-terms are succinctly encoded into finite quivers. By studying the Poincar\'e polynomial of the quiver moduli space using the Reineke formula, we can learn about such useful concepts as Donaldson-Thomas invariants, instanton transitions and supersymmetry breaking.Comment: 38 pages, 5 figures, 1 tabl

B-L Cosmic Strings in Heterotic Standard Models

E_{8} X E_{8} heterotic string and M-theory, when compactified on smooth Calabi-Yau manifolds with SU(4) vector bundles, can give rise to softly broken N=1 supersymmetric theories with the exact matter spectrum of the MSSM, including three right-handed neutrinos and one Higgs-Higgs conjugate pair of supermultiplets. These vacua have the SU(3)_{C} X SU(2)_{L} X U(1)_{Y} gauge group of the standard model augmented by an additional gauged U(1)_{B-L}. Their minimal content requires that the B-L symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed sneutrino. The soft supersymmetry breaking operators can induce radiative breaking of the B-L gauge symmetry with an acceptable B-L/electroweak hierarchy. In this paper, it is shown that U(1)_{B-L} cosmic strings occur in this context, potentially with both bosonic and fermionic superconductivity. We present a numerical analysis that demonstrates that boson condensates can, in principle, form for theories of this type. However, the weak Yukawa and gauge couplings of the right-handed sneutrino suggests that bosonic superconductivity will not occur in the simplest vacua in this context. The electroweak phase transition also disallows fermion superconductivity, although substantial bound state fermion currents can exist.Comment: 41 pages, 5 figure

Non-supersymmetric heterotic model building

We investigate orbifold and smooth Calabi-Yau compactifications of the non-supersymmetric heterotic SO(16)xSO(16) string. We focus on such Calabi-Yau backgrounds in order to recycle commonly employed techniques, like index theorems and cohomology theory, to determine both the fermionic and bosonic 4D spectra. We argue that the N=0 theory never leads to tachyons on smooth Calabi-Yaus in the large volume approximation. As twisted tachyons may arise on certain singular orbifolds, we conjecture that such tachyonic states are lifted in the full blow-up. We perform model searches on selected orbifold geometries. In particular, we construct an explicit example of a Standard Model-like theory with three generations and a single Higgs field.Comment: 1+30 pages latex, 11 tables; v2: references and minor revisions added, matches version published in JHE

Unifying generative and discriminative learning principles

<p>Abstract</p> <p>Background</p> <p>The recognition of functional binding sites in genomic DNA remains one of the fundamental challenges of genome research. During the last decades, a plethora of different and well-adapted models has been developed, but only little attention has been payed to the development of different and similarly well-adapted learning principles. Only recently it was noticed that discriminative learning principles can be superior over generative ones in diverse bioinformatics applications, too.</p> <p>Results</p> <p>Here, we propose a generalization of generative and discriminative learning principles containing the maximum likelihood, maximum a posteriori, maximum conditional likelihood, maximum supervised posterior, generative-discriminative trade-off, and penalized generative-discriminative trade-off learning principles as special cases, and we illustrate its efficacy for the recognition of vertebrate transcription factor binding sites.</p> <p>Conclusions</p> <p>We find that the proposed learning principle helps to improve the recognition of transcription factor binding sites, enabling better computational approaches for extracting as much information as possible from valuable wet-lab data. We make all implementations available in the open-source library Jstacs so that this learning principle can be easily applied to other classification problems in the field of genome and epigenome analysis.</p

Gauged Linear Sigma Models for toroidal orbifold resolutions

Toroidal orbifolds and their resolutions are described within the framework of (2,2) Gauged Linear Sigma Models (GLSMs). Our procedure describes two-tori as hypersurfaces in (weighted) projective spaces. The description is chosen such that the orbifold singularities correspond to the zeros of their homogeneous coordinates. The individual orbifold singularities are resolved using a GLSM guise of non-compact toric resolutions, i.e. replacing discrete orbifold actions by Abelian worldsheet gaugings. Given that we employ the same global coordinates for both the toroidal orbifold and its resolutions, our GLSM formalism confirms the gluing procedure on the level of divisors discussed by Lust et al. Using our global GLSM description we can study the moduli space of such toroidal orbifolds as a whole. In particular, changes in topology can be described as phase transitions of the underlying GLSM. Finally, we argue that certain partially resolvable GLSMs, in which a certain number of fixed points can never be resolved, might be useful for the study of mini-landscape orbifold MSSMs.Comment: 71 pages, 2 figure

HABITAT: A longitudinal multilevel study of physical activity change in mid-aged adults

Purpose. To explore the role of the neighborhood environment in supporting walking Design. Cross sectional study of 10,286 residents of 200 neighborhoods. Participants were selected using a stratified two-stage cluster design. Data were collected by mail survey (68.5% response rate). Setting. The Brisbane City Local Government Area, Australia, 2007. Subjects. Brisbane residents aged 40 to 65 years. Measures. Environmental: street connectivity, residential density, hilliness, tree coverage, bikeways, and street lights within a one kilometer circular buffer from each resident’s home; and network distance to nearest river or coast, public transport, shop, and park. Walking: minutes in the previous week categorized as < 30 minutes, ≥ 30 < 90 minutes, ≥ 90 < 150 minutes, ≥ 150 < 300 minutes, and ≥ 300 minutes. Analysis. The association between each neighborhood characteristic and walking was examined using multilevel multinomial logistic regression and the model parameters were estimated using Markov chain Monte Carlo simulation. Results. After adjustment for individual factors, the likelihood of walking for more than 300 minutes (relative to <30 minutes) was highest in areas with the most connectivity (OR=1.93, 99% CI 1.32-2.80), the greatest residential density (OR=1.47, 99% CI 1.02-2.12), the least tree coverage (OR=1.69, 99% CI 1.13-2.51), the most bikeways (OR=1.60, 99% CI 1.16-2.21), and the most street lights (OR=1.50, 99% CI 1.07-2.11). The likelihood of walking for more than 300 minutes was also higher among those who lived closest to a river or the coast (OR=2.06, 99% CI 1.41-3.02). Conclusion. The likelihood of meeting (and exceeding) physical activity recommendations on the basis of walking was higher in neighborhoods with greater street connectivity and residential density, more street lights and bikeways, closer proximity to waterways, and less tree coverage. Interventions targeting these neighborhood characteristics may lead to improved environmental quality as well as lower rates of overweight and obesity and associated chromic disease