Predefined-time robust contour tracking of robotic manipulators

Robotic tasks are primarily defined to comply to spatial and time constraints, and in several of such tasks, it is required to track a nominal contour depending just on spatial coordinates, without involving the time variable in the definition of such a contour, in contrast to conventional trajectory tracking schemes. With the aim to satisfy the salient requirements of these robotic tasks, this paper presents an integrated robust controller. The contour is encoded by using a robust velocity field, such that, any particle immerse in such field converges in predefined-time to a predefined vicinity of the given contour. Then, a robust controller is proposed to enforce the velocity field, in turns, in predefined-time. In this sense, a predefined-time-precision contour tracking is assured, by considering a robust controller that does not assume the exact knowledge of the robot parameters for its real-time implementation. Numerical simulations are conducted to highlight the reliability of the proposed scheme.     

Using matrix norms to estimate the direction of arrival of planar waves on an ULA

SEAD method estimates the direction-of-arrival angles on an uniformly linear array based on the difference between the two largest singular values, what is called differential spectrum. Although it presented an outstanding performance, the ability to indicate the source positions was not elucidated yet. Inspired by the differential spectrum formulation we derived a total differential spectrum and found out that the matrix norm induced by the vector 2-norm of a modified spatial covariance matrix can be used to estimate the direction-of-arrival of multiple plane waves. Indeed we show that matrix norms are estimators and we propose their use instead of the singular value decomposition in SEAD-based methods. We present a general mathematical expression in order to explicit the operating principles of the proposed methods. Consequently, we were able to explain how the relation between the arriving and the search angles produces the larger peaks on the differential spectrum. To evaluate the important role played by matrix norms, a thousand experiments were carried out. They showed that the proposed approach proved to be as accurate as the previous SEAD-based methods, while providing a significant reduction on runtime. It also outperformed well-established methods like MODEX regarding the estimation error.     

Interpretation of Score Reports by Diverse Subgroups of Parents

The degree to which diverse score users can understand and consume information presented in score reports dictates whether they are able to draw reasonable conclusions. The goal of this study was to understand how parents (a particularly understudied and heterogeneous stakeholder population) make interpretations from a hypothetical interactive score report. We used cognitive laboratories to evaluate how 35 parents from diverse educational and language proficiency backgrounds make sense of the information presented in hypothetical K-12 score reports. Results from this study demonstrate the diversity in the levels of comprehension across the assessed subgroups of parents, and highlight the need for and importance of additional support materials that can help parents understand and make sense of the information presented in score reports. Nevertheless, due to the hypothetical nature of the score report mockup evaluated and the small sample sizes, these results should be substantiated with additional research.     

Sermons,carrots or sticks? Explaining successful policy implementation in a low performance institution

This article explains how after 43 years of unsatisfactory outcomes, the Ministry of Education of Peru (MoE) suddenly ranked at the top of governmental performance tables. To do so, this study relies on implementation and major discussions of policy instrument theories to provide a comprehensive explanation of the reasons underlying the MoE’s improvements. Methodologically, this research employs the mixed research methods paradigm. It combines process-tracing and regression analysis. The analyses show that the MoE underwent three major events in its route to achieve policy success. First, the approval of a long-term policy plan (National Educative Plan to 2021); second, the contentious legitimisation of governmental policies against Peru’s teachers’ union and its eventual defeat; and, third, the recentralisation of historically dispersed control functions in the MoE. The results indicate that upon the occurrence of these reforms, MoE’s bureaucrats could gain teachers’ legitimacy and eventually achieve complementarity of policy tools. In fact, the multiple regression analysis suggests positive and significant interdependence between the set of tools employed by MoE officers: parents’ voluntary monetary contribution to schools (sermon), economic incentives to outperform schools (carrots) and trimestral oversight of schools’ performance (sticks). Results also show that MoE’s tools are positively associated with satisfactory student-learning outcomes.     

Validity of proximity sensor-based wear-time detection using the ActiGraph GT9X

Our study investigated the performance of proximity sensor-based wear-time detection using the GT9X under laboratory and free-living settings. Fifty-two volunteers (23.2 ± 3.8 y; 23.2 ± 3.7 kg/m²) participated in either a laboratory or free-living protocol. Lab participants wore and removed a wrist-worn GT9X on 3–5 occasions during a 3-hour directly observed activity protocol. The 2-day free-living protocol used an independent temperature sensor and self-report as the reference to determine if wrist and hip-worn GT9X accurately determined wear (i.e., sensitivity) and non-wear (i.e., specificity). Free-living estimates of wear/non-wear were also compared to Troiano 2007 and Choi 2012 wear/non-wear algorithms. In lab, sensitivity and specificity of the wrist-worn GT9X in detecting total minutes of wear-on and off was 93% and 49%, respectively. The GT9X detected wear-off more often than wear-on, but with a greater margin of error (4.8 ± 11.6 vs. 1.4 ± 1.4 min). In the free-living protocol, wrist and hip-worn GT9X’s yielded sensitivity and specificity of 72 and 90% and 84 and 92%, respectively. GT9X estimations had inferior sensitivity but superior specificity to Troiano 2007 and Choi 2012 algorithms. Due to inaccuracies, it may not be advisable to singularly use the proximity-sensor-based wear-time detection method to detect wear-time.     

Pigments and binders in “Madonna col Bambino e S. Giovannino” by Botticelli investigated by micro-Raman and GC/MS

During the restoration plan of the famous painting “Madonna col Bambino e S. Giovannino” by Sandro Botticelli, located in the Museo Civico of Piacenza (Italy), a study on painting materials was carried out. The pigments, the binders and the materials used for the application of ground and priming layers were studied using micro-Raman spectroscopy, gas chromatography coupled with mass spectrometry (GC/MS), optical and electronic microscopies. Gypsum and anhydrite were found in the ground layer, while carbon black and lead white were used in the priming layers. The precious pigments of the artist's palette and the binders used (egg and animal glue) were determined.     

一个无政府主义者的自然死亡

这个年代没有人会去深究上帝是否存在,也有人会不再认为他们读的圣经真的具有伟大的救赎之力能拯救世人脱离撒坦的阴暗。信仰在某种意义上。已经成为了一种纯粹供人们自我安慰的道德他律力量。所谓上帝的子民。在被消费主义日渐吞噬的现代社会浮沉之后,也不免会成为罪恶的祭品。     

未来的主人翁：NBA年轻一代领袖档案

1984年乔丹领衔的黄金一代,开辟了90年代NBA众星捧月的大场面,马克利、奥拉朱旺、尤因、雷吉·米勒、超音速双怪以及犹他二老与篮球之神迈克尔·乔丹的轮番PK造就了美国职业篮球最辉煌的时代。1996年选秀大会又为联盟输送了科比·布莱恩特、阿伦·艾弗森、雷·阿伦这一批优质球星,加上1997年的邓肯和麦迪以及1995年的凯文·加内特,这一拨人是1998年乔丹退役之后NBA的中坚力量。     

Combined training,FNDC5/irisin levels and metabolic markers in obese men: A randomised controlled trial

The effects of training on FNDC5/irisin and its association with fitness and metabolic marker improvements induced by training have been poorly investigated in humans. Thus, the present study assessed the effects of combined training (CT) on FNDC5/irisin levels, metabolic markers and fitness adaptations in obese men. Middle-age obese men (age 49.13?±?5.75, body mass index (BMI) 30.86?±?1.63) were randomly distributed in the CT group (n?=?12) and control group (CG n?=?10). The CT consisted of strength followed by aerobic training, 3 times/week, for 24 weeks. Body composition, physical fitness, plasma FNDC5/irisin, biochemical markers and metabolic scores/index were evaluated. CT maintained FNDC5/irisin levels (µg/mL) (pre: 4.15?±?0.32, post: 4.21?±?0.32; p?=?.96) and improved body composition, metabolic and physical fitness markers. In the CG, decreased FNDC5/irisin (µg/mL) (pre: 4.36?±?0.23, post: 3.57?±?0.94; p?=?.01) and reduced strength (supine exercise/kg) (pre: 71?±?14.7, post: 60.1?±?14.05; p?<?.01) were observed, along with a trend to increase HOMA-IR (pre: 2.63?±?1.11, post: 3.14?±?1.27; p?=?.07) and other indicators of metabolic deterioration. An inverse correlation was found between the change (Δ%) in levels of FNDC5/irisin and Δ% glucose, Δ% total cholesterol, Δ% triglycerides and Δ% waist circumference, in addition to a positive relation with Δ% muscle strength. In conclusion, CT maintained FNDC5/irisin levels and provided metabolic and fitness benefits. The correlation between FNDC5/irisin changes and metabolic parameters, as well as the FNDC5/irisin reduction associated with fitness and metabolic worsening in the CG, suggests a relationship between FNDC5/irisin and a healthy metabolic status in humans.