Adding Compression to Block Addressing Inverted Indexes

Inverted index compression, block addressing and sequential search on compressed text are three techniques that have been separately developed for efficient, low-overhead text retrieval. Modern text compression techniques can reduce the text to less than 30% of its size and allow searching it directly and faster than the uncompressed text. Inverted index compression obtains significant reduction of its original size at the same processing speed. Block addressing makes the inverted lists point to text blocks instead of exact positions and pay the reduction in space with some sequential text scanning.In this work we combine the three ideas in a single scheme. We present a compressed inverted file that indexes compressed text and uses block addressing. We consider different techniques to compress the index and study their performance with respect to the block size. We compare the index against three separate techniques for varying block sizes, showing that our index is superior to each isolated approach. For instance, with just 4% of extra space overhead the index has to scan less than 12% of the text for exact searches and about 20% allowing one error in the matches.     

The Network Orientations of Highly Resilient Urban Minority Youth: A Network-Analytic Account of Minority Socialization and Its Educational Implications

In this article the authors present a critical assessment of existing characterizations of resiliency and help-seeking behavior in light of their relevance to issues of minority youth socialization and schooling. In this effort, they reconceptualize the notion of resiliency within an analysis that highlights the more contextual aspects of how minority adolescent cope with structural forces that threaten healthy development. They show how key developmental transitions are thwarted by social forces that undermine the development of supportive relationships across multiple institutional sites (e.g., family, neighborhood, school). They also explain how resiliency is associated with egocentric networks that exhibit key structural characteristics. The authors conclude by discussing the implications of a critical network-analytic model of minority socialization in the development of future educational and youth mediations and reforms.     

University Efficiency: Complementariness versus Trade‐off between Teaching,Research and Administrative Activities

University managers should be aware of the importance that efficiency has for their own universities, orientating their actions towards research and teaching excellence. This study estimates teaching and research efficiency of the different departments of a university and tests the complementariness versus trade‐off between them. The results obtained show high levels of efficiency for the departments analysed, which is important for budget allocation, as one of the main challenges faced by a university is the allocation of budgets to different departments. The results also support the trade‐off between teaching efficiency and research activity, the complementariness between teaching efficiency and research efficiency, between research efficiency and time deducted from teaching, as well as the complementariness between research efficiency and administration activity.     

Turning Ideologies Inside Out: Developing Young Readers’ Empathy for Critical Voices in Narrative Fiction

This article is located at the crossroads between two distinctive human traits, empathy and rational thought, with narrative emerging as a particularly powerful means to enable young readers to bring them together. Specifically, we discuss the role that critical literary exegesis plays in the development of empathic consciousness in literary readers. The discussion is conducted through the critical narrative discourse analysis of a short story that is widely read by Portuguese young students. The story deals with what has become a living experience for many students – emigration – and puts opposing social ideologies about this experience in a subtle dialogue. Narratological critical analysis provides an essential tool for readers to turn those ideologies inside out. It enables them to escape the main character’s conformist positioning and develop a liberating empathy, and hence a more sensitive perspective about the social reality that the narrator offers for our consideration.     

Web knowledge sharing and its effect on innovation: an empirical investigation in SMEs

This paper extends previous studies on knowledge management by analysing factors affecting Web Knowledge Sharing (WKS) in small- and medium-sized enterprises (SMEs). In addition, the impact of WKS on organizational innovation and the moderating effect of IT skills on this relation are analysed. Grounded in the technology-organization-environment (TOE) theory and the resource-based view (RBV), this paper develops an integrative research model, which analyses these relations using structural equation modelling on a data set of 535 Spanish SMEs. Results suggest that technological and organizational factors – IT expertise and commitment-based human resources practices – positively influence WKS, while the contrary is found for environmental factors (customer power). In addition, results show that WKS contributes positively to organizational innovation, though support for the moderating effect of IT skills in this relation is not found. The main conclusions of this research can be valuable to SMEs that use or intend to use Internet technologies for knowledge management.     

Anticipatory strategies of team-handball goalkeepers

This study seeks to discover whether handball goalkeepers employ a general anticipatory strategy when facing long distance throws and the effect of uncertainty on these strategies. Seven goalkeepers and four throwers took part. We used a force platform to analyse the goalkeeper's movements on the basis of reaction forces and two video cameras synchronised at 500 Hz to film the throw using 3D video techniques. The goalkeepers initiated their movement towards the side of the throw 193 ± 67 ms before the release of the ball and when the uncertainty was reduced the time increased to 349 ± 71 ms. The kinematics analysis of their centre of mass indicated that there was an anticipatory strategy of movement with certain modifications when there was greater uncertainty. All the average scores referring to velocity and lateral movement of the goalkeeper's centre of mass are significantly greater than those recorded for the experimental situation with bigger uncertainty. The methodology used has enabled us to tackle the study of anticipation from an analysis of the movement used by goalkeepers to save the ball.     

Asymmetry of red blood cell motions in a microchannel with a diverging and converging bifurcation

In microcirculation, red blood cells (RBCs) flowing through bifurcations may deform considerably due to combination of different phenomena that happen at the micro-scale level, such as: attraction effect, high shear, and extensional stress, all of which may influence the rheological properties and flow behavior of blood. Thus, it is important to investigate in detail the behavior of blood flow occurring at both bifurcations and confluences. In the present paper, by using a micro-PTV system, we investigated the variations of velocity profiles of two working fluids flowing through diverging and converging bifurcations, human red blood cells suspended in dextran 40 with about 14% of hematocrit level (14 Hct) and pure water seeded with fluorescent trace particles. All the measurements were performed in the center plane of rectangular microchannels using a constant flow rate of about 3.0 × 10⁻¹² m³/s. Moreover, the experimental data was compared with numerical results obtained for Newtonian incompressible fluid. The behavior of RBCs was asymmetric at the divergent and convergent side of the geometry, whereas the velocities of tracer particles suspended in pure water were symmetric and well described by numerical simulation. The formation of a red cell-depleted zone immediately downstream of the apex of the converging bifurcation was observed and its effect on velocity profiles of RBCs flow has been investigated. Conversely, a cell-depleted region was not formed around the apex of the diverging bifurcation and as a result the adhesion of RBCs to the wall surface was enhanced in this region.     

Impact sports and bone fractures among adolescents

The objective of the present study was to investigate the effects of different sports on stress fractures among adolescents during a 9-month follow-up period. The sample was composed of 184 adolescents divided into three groups (impact sports [n = 102]; swimming [n = 35]; non-sports [n = 47]). The occurrence of stress fracture was reported by participants and coaches. As potential confounders we considered age, sex, resistance training, body composition variables and age at peak of height velocity. There were 13 adolescents who reported fractures during the 9-month period. Bone mineral density values were higher in adolescents engaged in impact sports (P-value = 0.002). Independently of confounders, the risk of stress fracture was lower in adolescents engaged in impact sports than in non-active adolescents (hazard ratio [HR] = 0.23 [95% confidence interval (CI) = 0.05 to 0.98]), while swimming practice was not associated to lower risk of fracture (HR = 0.49 [95% CI = 0.09 to 2.55]). In conclusion, the findings from this study indicate the importance of sports participation among adolescents in the reduction of stress fracture risk, especially with impact sports. More importantly, these results could be relevant for recognising adolescents in danger of not reaching their potential for peak bone mass and later an increased risk of fractures.     

Validity of a portable force platform for assessing biomechanical parameters in three different tasks

The aim of this study was to determine the precision and accuracy of the vertical and anterior–posterior force components of the portable PASCO PS-2142 force plate. Impulse, peak force, and time to peak force were assessed and compared to a gold standard force plate in three different tasks: vertical jump, forward jump, and sprint start. Two healthy male participants performed ten trials for each task, resulting in 60 trials. Data analyses revealed good precision and accuracy for the vertical component of the portable force plate, with relative bias and root mean square (RMS) error values nearly the same in all tasks for the impulse, time to peak force, and peak force parameters. Precision and accuracy of the anterior–posterior component were lower for the impulse and time to peak force, with relative bias and RMS error values nearly the same between tasks. Despite the lower precision and accuracy of the anterior–posterior component of the portable force plate, these errors were systematic, reflecting a good repeatability of the measure. In addition, all variables presented good agreement between the portable and gold standard platforms. Our results provide a good perspective for using the aforementioned portable force plate in sports and clinical biomechanics.