Classroom composition and quality in early childhood education: a systematic review

High-quality early childhood education appears to be particularly beneficial for disadvantaged children, since it may help reduce an initial achievement gap. Yet, these children are frequently enrolled in disadvantaged classrooms with lower quality levels. Thus, classroom composition and quality may be associated, but evidence is scarce. In this review, we gathered evidence regarding classroom composition indexes and their association with observed classroom quality, reported in 25 studies that met the inclusion criteria. The majority of studies were conducted in the United States, with disadvantaged samples of children. Classroom composition indexes used were mainly calculations of the percentage, proportion, and average/mean of a particular type of characteristic at the classroom level, that generally captured classroom homogeneity. Most studies focused on minority and socioeconomic status. ECERS and CLASS were the most frequently used standardized observation measures of classroom quality. Evidence suggests that in classrooms with a high concentration of children with social minority status and from low income families, quality tends to be lower, particularly on the CLASS emotional and instructional support domains. Additional research, particularly outside the USA, focused primarily on the association between different types of classroom composition and ECE quality is warranted.info:eu-repo/semantics/acceptedVersio

Connectivity-Enforcing Hough Transform for the Robust Extraction of Line Segments

Global voting schemes based on the Hough transform (HT) have been widely used to robustly detect lines in images. However, since the votes do not take line connectivity into account, these methods do not deal well with cluttered images. In opposition, the so-called local methods enforce connectivity but lack robustness to deal with challenging situations that occur in many realistic scenarios, e.g., when line segments cross or when long segments are corrupted. In this paper, we address the critical limitations of the HT as a line segment extractor by incorporating connectivity in the voting process. This is done by only accounting for the contributions of edge points lying in increasingly larger neighborhoods and whose position and directional content agree with potential line segments. As a result, our method, which we call STRAIGHT (Segment exTRAction by connectivity-enforcInG HT), extracts the longest connected segments in each location of the image, thus also integrating into the HT voting process the usually separate step of individual segment extraction. The usage of the Hough space mapping and a corresponding hierarchical implementation make our approach computationally feasible. We present experiments that illustrate, with synthetic and real images, how STRAIGHT succeeds in extracting complete segments in several situations where current methods fail.Comment: Submitted for publicatio

Growth, Centrism and Semi-Presidentialism: Forecasting the Portuguese General Elections

Electoral behaviour in recently established democracies has been more frequently treated from the point of view of its unpredictability, volatility and personalistic elements than that of its "fundamentals". In this paper, we wish to contribute to redress this imbalance by advancing a forecasting model for general elections in a young democracy, Portugal. Building on the very familiar notion that the vote for the incumbent can be predicted on the basis of "economics" and "politics", we capture "economics" through a nonlinear specification of economic growth. Furthermore, we include two structural features of Portuguese politics, which have entailed a systematic electoral punishment for the centre-left Socialist Party as the incumbent and for all incumbents involved in political conflicts with the elected president in Portugal's semi-presidentialism.Forecasting; Portuguese general elections; Economics and elections; Semi-Presidentialism

Referendum Design, Quorum Rules and Turnout

In this article, we focus on the consequences of quorum requirements for turnout in referendums. We use a rational choice, decision theoretic voting model to demonstrate that participation quorums change the incentives some electors face, inducing those who oppose changes in the status quo and expect to be in the minority to abstain. As a result, paradoxically, participation quorums decrease electoral participation. We test our model’s predictions using data for all referendums held in current European Union countries from 1970 until 2007, and show that the existence of a participation quorums increases abstention by more than ten percentage points.Referendum Design; Voter turnout

Majorana bound states in open quasi-1D and 2D systems with transverse Rashba coupling

We study the formation of Majorana states in quasi-1D and 2D square lattices with open boundary conditions, with general anisotropic Rashba coupling, in the presence of an applied Zeeman field and in the proximity of a superconductor. For systems in which the length of the system is very large (quasi-1D) we calculate analytically the exact topological invariant, and we find a rich phase diagram which is strongly dependent on the width of the system. We compare our results with previous results based on a few-band approximation. We also investigate numerically open 2D systems of finite length in both directions. We use the recently introduced generalized Majorana polarization, which can locally evaluate the Majorana character of a given state. We find that the formation of Majoranas depends strongly on the geometry of the system and if the length and the width are comparable no Majorana states can form, however, one can show the formation of "quasi-Majorana" states that have a local Majorana character, but no global Majorana symmetry.Comment: 12 pages, 13 figure

How quorum rules distort referendum outcomes: evidence from a pivotal voter model

In many jurisdictions, whether referendum results are binding depend on certain legally defined quorum requirements. With a pivotal-voter model, we examine how quorum requirements affect voter’s behavior. We conclude that quorums can be the cause of lower turnout and that they can deliver outcomes that are an inadequate basis to make inferences about collective preferences. We further conclude that quorums may help minorities to impose their will on majorities and that they may create a bias against the status quo. Finally, they generate situations under which the secrecy of the vote is called into question.

Event-by-event analysis of ultra-relativistic heavy-ion collisions in smoothed particle hydrodynamics

The method of smoothed particle hydrodynamics (SPH) is applied for ultra-relativistic heavy-ion collisions. The SPH method has several advantages in studying event-by-event fluctuations, which attract much attention in looking for quark gluon plasma (QGP) formation, because it gives a rather simple scheme for solving hydrodynamical equations. Using initial conditions for Au+Au collisions at RHIC energy produced by NeXus event generator, we solve the hydrodynamical equation in event-by-event basis and study the fluctuations of hadronic observables such as dN/dy due to the initial conditions. In particular, fluctuations of elliptic flow coefficient v2 is investigated for both the cases, with and without QGP formation. This can be used as an additional test of QGP formation.Comment: LaTeX, 16 figures, 3 tables, 23 pages. Talk presented at 6th International Workshop on Relativistic Aspects of Nuclear Physics(RANP2000), Caraguatatuba, Tabatinga Beach, Sao Paulo, Brazil, October 17-20, 2000. To be published in the proceedings (World Scientific, Singapore

Event-by-event fluctuations in hydrodynamical description of heavy-ion collisions

Effects caused by the event-by-event fluctuation of the initial conditions in hydrodynamical description of high-energy heavy-ion collisions are investigated. Non-negligible effects appear for several observable quantities, even for a fixed impact parameter $\vec b$. They are sensitive to the equation of state, being the dispersions of the observable quantities in general smaller when the QGP phase appears at the beginning of hydrodynamic evolution than when the fluid remains hadron gas during whole the evolution.Comment: 4 pages, 4 figures, talk presented to Quark Matter 2001 Conferenc