The graceful exit in pre-big bang string cosmology

We re-examine the graceful exit problem in the pre-big bang scenario of string cosmology, by considering the most general time-dependent classical correction to the Lagrangian with up to four derivatives. By including possible forms for quantum loop corrections we examine the allowed region of parameter space for the coupling constants which enable our solutions to link smoothly the two asymptotic low-energy branches of the pre-big bang scenario, and observe that these solutions can satisfy recently proposed entropic bounds on viable singularity free cosmologies.Comment: 14 pages, 6 figures, JHEP class. Added new section on the classical correction and reference

Cosmological perturbations and the transition from contraction to expansion

We investigate both analytically and numerically the evolution of scalar perturbations generated in models which exhibit a smooth transition from a contracting to an expanding Friedmann universe. We find that the resulting spectral index in the late radiation dominated universe depends on which of the $\Psi$ or \$zeta$ variables passes regularly through the transition. The results can be parameterized through the exponent $q$ defining the rate of contraction of the universe. For $q \geq -1/2$ we find that there are no stable cases where both variables are regular during the transition. In particular, for $0<q\ll 1$, we find that the resulting spectral index is close to scale invariant if $\Psi$ is regular, whereas it has a steep blue behavior if $\zeta$ is regular. We also show that as long as $q\leqslant 1$, perturbations arising from the Bardeen potential remain small during contraction in the sense that there exists a gauge in which all the metric and matter perturbation variables are small.Comment: 30 pages, 16 figures. Version to appear in Phys. Rev. D. Slight modifications, but no change in the conclusio

Urban, Mobile and Global

PEOPLE IN URBAN China travel, move house and commute longer distances than ever before. They also enjoy greater opportunities to change their lifestyles or move up the social ladder. The gradual removal of historical bans imposed by the Communist Party on unauthorised movement between cities (or from the countryside to the city) as well as owning property and travelling abroad make the ease of movement — mobility — novel and exciting. Over the past year and a half, the anticorruption campaign has identified ‘excessive mobility’, as defined by all forms of ‘extravagance’ 铺张 or 奢靡 on the part of party and government officials, as being a danger to the wellbeing of the party-state. New prohibitions and regulations have put pressure on party and government officials to change their habits, alter their lifestyles and abandon any plans to establish a residential base overseas — in effect, to retreat from the Zeitgeist of mobility. This chapter considers the implications for the Shared Destiny of the Chinese in the context of movement between China and the world, particularly in relation to the Party’s seemingly stringent anti-waste regulations

Urban Growth, Rescaling and the Spatial Administrative Hierarchy

After thirty years of scholarship on transformations in China under reform, accumulated research capacity demonstrates potential for increased interdisciplinary research and research questions at the interstices of fields. This paper examines one such possibility by assessing urbanization in relation to the dynamics of financial policy and rescaling through the spatial administrative hierarchy. From the perspective of the administrative hierarchy, the discussion observes the conjunctures of de/recentralization in the economy with urbanization through the establishment of new cities. Based on the work of Victor Shih on inflationary cycles, the paper demonstrates coordination of monetary policy with designation of new cities, and ultimately argues that the central government has orchestrated decentralization of economic power in association with planned urbanization as a basis of domestic growth

Stratégies d’apprentissage par la lecture rapportées par des élèves en difficulté d’apprentissage de première secondaire en classe de cheminement particulier de formation

Le but de cette étude consiste à décrire les stratégies d’apprentissage par la lecture rapportées par des élèves en difficulté d’apprentissage de première secondaire en classe de cheminement particulier (CP). Pour ce faire, deux objectifs sont poursuivis : (a) décrire les stratégies cognitives et d’autorégulation que ces élèves disent utiliser ; et (b) comparer ce portrait à celui rapporté par des élèves de première secondaire en classe ordinaire (CO). Le questionnaire « Lire pour apprendre » a été rempli par 111 élèves en CP et par 102 élèves en CO de la grande région de Montréal. Les résultats indiquent que les élèves en CP utilisent des stratégies peu efficaces et que leur portrait stratégique se démarque en certains aspects de celui des élèves en CO. Ces résultats sont discutés au regard d’un modèle d’apprentissage par la lecture.The aim of this study is to describe strategies for learning through reading as reported by students with learning difficulties in a secondary one level “special track” class (CP). Two objectives include a) to describe cognitive strategies and self-regulation strategies that these students report, and b) to compare this portrait with that reported by regular class secondary one students (CO). The questionnaire “Reading to Learn” was administered to 111 students in CP and 102 students in CO in the greater Montreal region. The results show that CP students use strategies that have poor efficiency and that the portrait of their strategies is differentiated in certain aspects from that of the CO students. These results are discussed in light of a model of learning through reading.El propósito de este estudio consiste en describir las estrategias de aprendizaje por medio de la lectura, relatadas por alumnos en dificultad de aprendizaje de primer año de secundaria con itinerario particular de formación (CP). Para esto, se persiguen dos objetivos: (a) describir las estrategias cognitivas y de autorregulación que estos alumnos dicen utilizar; y (b) comparar este retrato a él relatado por alumnos de primer año de secundaria en clase normal (CO)*. El cuestionario « Leer para aprender » fue llenado por 111 alumnos en CP y por 102 alumnos en CO de la gran región de Montreal. Los resultados indican que los alumnos en CP utilizan estrategias poco eficaces y que su retrato estratégico se demarca en ciertos aspectos de él de los alumnos en CO. Estos resultados son analizados respecto a un modelo de aprendizaje por medio de la lectur

Study of symmetry in F(R) theory of gravity

An action in which the Ricci scalar is nonminimally coupled with a scalar field and contains higher order curvature invariant terms carries a conserved current under certain conditions that decouples geometric part from the scalar field. The conserved current relates the pair of arbitrary coupling parameters $f(\phi)$ and $\omega(\phi)$ with the gravitational field variable, where $\omega(\phi)$ is the Brans-Dicke coupling parameter. The existence of such conserved current may be helpful to sketch the cosmological evolution from its early age till date in a single frame.Comment: 6 page

Diagnosis of hepatocellular carcinoma

AbstractMore than 90% of cases of hepatocellular carcinoma occur on the background of chronic liver disease. Its diagnosis should therefore be based on six-month ultrasound screening, which should be started in these patients. The positive diagnosis of hepatocellular carcinoma is based on its vascularization examined on dynamic CT or MRI images after contrast enhancement. Arterial hypervascularization followed by a washout from the lesion in the portal and/or late phases on a background of cirrhosis provides a positive diagnosis of HCC without histology for nodules over a centimeter in size (international guidelines). Any other appearances require needle biopsy of the nodule and extra-nodular area to confirm the diagnosis. The local staging assessment predominantly involving portal invasion and the general patient assessment should be combined with assessment of the underlying liver disease to guide the treatment decision. The information obtained should be contained in as standardized a report as possible with all of the information required for patient management

An artificial neural network for estimating haplotype frequencies

The problem of estimating haplotype frequencies from population data has been considered by numerous investigators, resulting in a wide variety of possible algorithmic and statistical solutions. We propose a relatively unique approach that employs an artificial neural network (ANN) to predict the most likely haplotype frequencies from a sample of population genotype data. Through an innovative ANN design for mapping genotype patterns to diplotypes, we have produced a prototype that demonstrates the feasibility of this approach, with provisional results that correlate well with estimates produced by the expectation maximization algorithm for haplotype frequency estimation. Given the computational demands of estimating haplotype frequencies for 20 or more single-nucleotide polymorphisms, the ANN approach is promising because its design fits well with parallel computing architectures