Three-feature model to reproduce the topology of citation networks and the effects from authors’ visibility on their h-index

Various factors are believed to govern the selection of references in citation networks, but a precise, quantitative determination of their importance has remained elusive. In this paper, we show that three factors can account for the referencing pattern of citation networks for two topics, namely “graphenes” and “complex networks”, thus allowing one to reproduce the topological features of the networks built with papers being the nodes and the edges established by citations. The most relevant factor was content similarity, while the other two – in-degree (i.e. citation counts) and age of publication – had varying importance depending on the topic studied. This dependence indicates that additional factors could play a role. Indeed, by intuition one should expect the reputation (or visibility) of authors and/or institutions to affect the referencing pattern, and this is only indirectly considered via the in-degree that should correlate with such reputation. Because information on reputation is not readily available, we simulated its effect on artificial citation networks considering two communities with distinct fitness (visibility) parameters. One community was assumed to have twice the fitness value of the other, which amounts to a double probability for a paper being cited. While the h-index for authors in the community with larger fitness evolved with time with slightly higher values than for the control network (no fitness considered), a drastic effect was noted for the community with smaller fitness.     

Constitutive Pluralism of Chemistry: Thought Planning, Curriculum, Epistemological and Didactic Orientations

Maybe the most difficult aspect of thinking about chemistry arises from the fact that chemistry isn’t an homogeneous subject. As a central science, it draws on a range of philosophical perspectives which in turn can result in different cognitive, learning and teaching styles in chemical education. This idea, apparently non-controversial, needs to be validated by more research. Without assuming this constitutive pluralism, describing it, and determining it, it becomes difficult to think of curricular goals and content. Thus, if we intend to improve the teaching of chemistry it is necessary, first, to assume explicitly this constitutive pluralism, then to map it in order to find the guiding principles: first for the mind (thought process), then for the curriculum and finally for the teaching, in such a way that it is as close as possible to the chemical way of operating and thinking. This is the aim of this paper. It reports the authors’ experiences in drafting structural ideas and planning for the subject “didactic of chemistry” based on the philosophy of chemistry at the University of Porto in Portugal.     

互补性与次协调性

玻尔互补性原理的准确意义已引起了许多争论。这里我们并不打算对玻尔的观点进行详细的评论,而是对在一种明确的意义上包含互补性被我们称之为C-理论的理论所能理解的东西作尽可能有道理的解释。那些理论的基本逻辑是一种通过对经典逻辑的演绎概念作恰当修改而得到的所谓＂次经典＂逻辑。粗略地说,C-理论是含有＂物理上＂不相容定理（尤其是矛盾定理）的非平庸理论。因此,其基本逻辑是一种次协调逻辑。本文被视为我们有关C-理论及其应用的一系列作品的第一篇。     

Output-feedback binary adaptive control of MIMO systems using monitoring function

The problem of adaptive control design for multivariable linear time-invariant plants with unknown control direction is considered. A solution is proposed based on the SDU factorization of the high frequency gain matrix (HFG) and the monitoring function approach. The adaptation scheme is the binary model reference adaptive control (BMRAC) which utilizes parameter projection and sufficiently high adaptation gains. The signs of the leading principal minors of the HFG define the control directions, and the lack of knowledge of which is a major challenge in the multivariable framework. The role of the monitoring function is to monitor the output error transient and then provide the necessary changes of the adaptation gain signs to guarantee a stable adaptive control. In addition to proving the signal boundedness of the resulting closed-loop system, the output tracking error is shown to be asymptotically as well as exponentially practically stable, i.e., exponentially stable with respect to a small residual compact set of size inversely proportional to the BMRAC adaptation gain. The latter implies good transient properties of the output tracking error in contrast to conventional adaptive laws which only guarantee asymptotic stability but can lead to extremely slow error convergence. The extension of the proposed approach to matched disturbances is also briefly discussed following the classical paradigm of disturbance estimators. Numerical results with a visual servoing application illustrate the efficiency of the proposed method.     

Query reformulation mining: models,patterns, and applications

Understanding query reformulation patterns is a key task towards next generation web search engines. If we can do that, then we can build systems able to understand and possibly predict user intent, providing the needed assistance at the right time, and thus helping users locate information more effectively and improving their web-search experience. As a step in this direction, we build a very accurate model for classifying user query reformulations into broad classes (generalization, specialization, error correction or parallel move), achieving 92% accuracy. We then apply the model to automatically label two very large query logs sampled from different geographic areas, and containing a total of approximately 17 million query reformulations. We study the resulting reformulation patterns, matching some results from previous studies performed on smaller manually annotated datasets, and discovering new interesting reformulation patterns, including connections between reformulation types and topical categories. We annotate two large query-flow graphs with reformulation type information, and run several graph-characterization experiments on these graphs, extracting new insights about the relationships between the different query reformulation types. Finally we study query recommendations based on short random walks on the query-flow graphs. Our experiments show that these methods can match in precision, and often improve, recommendations based on query-click graphs, without the need of users’ clicks. Our experiments also show that it is important to consider transition-type labels on edges for having recommendations of good quality.     

School science as a rite of passage: A new frame for familiar problems

The purpose of this article is twofold: to characterize and describe school science as a rite of passage, and to expose problems in school science that are made visible through the use of this metaphor. Like other rite-of-passage studies by van Gennep, Turner, and White, school-science-as-a-rite-of-passage follows the classic model: First, science students are separated from other students through their enrollment in introductory science classes and laboratory (the phase of separation). Science students are then secluded in the classroom and laboratory where a specialized body of knowledge unique to the scientific community is transmitted to them (the phase of transition). Eventually, students are presented via graduation ceremonies to the ordinary world with accompanying changes in their status and rights (the phase of reincorporation). However, unlike traditional passage rites, school science is a lengthy and ambiguous process that muddles the points of separation and reincorporation and fails to clarify the value of transition rituals.     

Beauty,effort and talent: a brief history of Brazilian women’s soccer in press discourse

This essay offers a brief historical background to the evolution of women’s soccer in Brazil. It focuses on the main obstacles women faced to pursue the game, which was forbidden to women in Brazil in 1941. By analysing how the newspapers treat women’s teams, the essay will try to highlight significant changes in the stereotypes that long guided perceptions of people about women soccer players.     

Determining the minimum number of passive stretches necessary to alter musculotendinous stiffness

Abstract

In this study, we examined the minimum number of constant-torque passive stretches necessary to reduce musculotendinous stiffness. Thirteen healthy individuals (mean age 22 years, s = 3; stature 1.67 m, s = 0.1; mass 66 kg, s = 13 kg) volunteered to participate in the investigation and underwent four 30-s constant-torque passive stretches of the plantar flexor muscles. Musculotendinous stiffness was examined from the angle–torque curves generated prior to the passive stretches, at the beginning of each 30-s stretch, and immediately following the four 30-s passive stretches. The results indicated that musculotendinous stiffness of the plantar flexors was reduced following two 30-s constant-torque passive stretches (P < 0.05) compared with the pre- musculotendinous stiffness assessment. Musculotendinous stiffness remained depressed following the third and fourth stretches, but did not decrease further. These findings suggest that two 30-s bouts of constant-torque passive stretching may be necessary to cause a significant decrease in musculotendinous stiffness of the plantar flexor muscles.     

Water-Based Aerobic Training Successfully Improves Lipid Profile of Dyslipidemic Women: A Randomized Controlled Trial

Purpose: This study aimed to investigate the effects of water-based aerobic training on the lipid profile and lipoprotein lipase (LPL) levels in premenopausal women with dyslipidemia. Method: Forty women were randomly assigned to: aquatic training (WA; n = 20) or a control group (CG; n = 20). The WA group underwent 12 weeks of water-based interval aerobic training twice a week at intensities ranging from 9 to 15 on the Borg Scale of Perceived Exertion. Total cholesterol (TC), triglycerides (TG), high- (HDL) and low- (LDL) density lipoprotein, TC/HDL ratio, LPL levels, and peak oxygen consumption (VO₂peak) were evaluated before and after 12 weeks in both groups. Results: The WA group elicited decreases in TC (9%; effect size [ES] = 0.69; 95% CI [0.05, 1.33]), LDL (16%; ES = 0.78; 95% CI [0.13, 1.42]), and the TC/HDL ratio (17%; ES = 1.13; 95% CI [0.46, 1.79]), as well as increases in VO₂peak (10%; ES = 0.64; 95% CI [0.002, 1.27]) and HDL (10%; ES = 0.28; 95% CI [?0.35. 0.90]), without significant changes in TG (ES = 0.16; 95% CI [?0.46, 1.79]) and LPL (ES = 0.36; 95% CI [?0.27, 0.98]) levels. In the CG, no statistically significant changes in any of these variables were found (TC, ES = 0.19, 95% CI [?0.43, 0.82]; LDL, ES = 0.22, 95% CI [?0.40, 0.85]; HDL, ES = 0.05, 95% CI [?0.57, 0.67]; TG, ES = 0.09, 95% CI [?0.53, 0.71]; TC/HDL ratio, ES = 0.20, 95% CI [?0.42, 0.82]; LPL, ES = 0.02, 95% CI [?0.60, 0.64]; VO₂peak, ES = 0.20, 95% CI [?0.42, 0.82]). Conclusion: Water-based interval aerobic training positively affected the lipid profile in premenopausal dyslipidemic women.