The cerebellum could solve the motor error problem through error increase prediction

We present a cerebellar architecture with two main characteristics. The first one is that complex spikes respond to increases in sensory errors. The second one is that cerebellar modules associate particular contexts where errors have increased in the past with corrective commands that stop the increase in error. We analyze our architecture formally and computationally for the case of reaching in a 3D environment. In the case of motor control, we show that there are synergies of this architecture with the Equilibrium-Point hypothesis, leading to novel ways to solve the motor error problem. In particular, the presence of desired equilibrium lengths for muscles provides a way to know when the error is increasing, and which corrections to apply. In the context of Threshold Control Theory and Perceptual Control Theory we show how to extend our model so it implements anticipative corrections in cascade control systems that span from muscle contractions to cognitive operations.Comment: 34 pages (without bibliography), 13 figure

Excited State Specific Multi-Slater Jastrow Wave Functions

We combine recent advances in excited state variational principles, fast multi-Slater Jastrow methods, and selective configuration interaction to create multi-Slater Jastrow wave function approximations that are optimized for individual excited states. In addition to the Jastrow variables and linear expansion coefficients, this optimization includes state-specific orbital relaxations in order to avoid the compromises necessary in state-averaged approaches. We demonstrate that, when combined with variance matching to help balance the quality of the approximation across different states, this approach delivers accurate excitation energies even when using very modest multi-Slater expansions. Intriguingly, this accuracy is maintained even when studying a difficult chlorine-anion-to-$\pi^{*}$ charge transfer in which traditional state-averaged multi-reference methods must contend with different states that require drastically different orbital relaxations.Comment: 16 pages, 6 figures, 2 table

Designing experiments using digital fabrication in structural dynamics

In engineering, traditional approaches aimed at teaching concepts of dynamics to engineering students include the study of a dense yet sequential theoretical development of proofs and exercises. Structural dynamics are seldom taught experimentally in laboratories since these facilities should be provided with expensive equipment such as wave generators, data-acquisition systems, and heavily wired deployments with sensors. In this paper, the design of an experimental experience in the classroom based upon digital fabrication and modeling tools related to structural dynamics is presented. In particular, all experimental deployments are conceived with low-cost, open-source equipment. The hardware includes Arduino-based open-source electronics whereas the software is based upon object-oriented open-source codes for the development of physical simulations. The set of experiments and the physical simulations are reproducible and scalable in classroom-based environments.Peer ReviewedPostprint (author's final draft

Hip Arthroscopic Surgery for Femoroacetabular Impingement: A Prospective Analysis of the Relationship Between Surgeon Experience and Patient Outcomes.

Background:Hip arthroscopic surgery is a rapidly growing procedure, but it may be associated with a steep learning curve. Few studies have used patient-reported outcome (PRO) surveys to investigate the relationship between surgeon experience and patient outcomes after the arthroscopic treatment of femoroacetabular impingement (FAI). Hypothesis:Patients undergoing hip arthroscopic surgery for the treatment of FAI in the early stages of a surgeon's career will have significantly worse outcomes and longer procedure times compared with patients treated after the surgeon has gained experience. Study Design:Cohort study; Level of evidence, 2. Methods:Patients undergoing hip arthroscopic surgery for FAI and labral injuries were prospectively enrolled during a sports medicine fellowship-trained surgeon's first 15 months of practice. Patients were stratified into an early group, consisting of the first 30 consecutive cases performed by the surgeon, and a late group, consisting of the second 30 consecutive cases. Radiographic and physical examinations were performed preoperatively and postoperatively. PRO surveys, including the 12-item Short Form Health Survey (SF-12), the modified Harris Hip Score (mHHS), and the Hip disability and Osteoarthritis Outcome Score (HOOS), were administered preoperatively and at a minimum of 1 year postoperatively. Results:There was no difference between the early and late groups for patient age (37.2 ± 11.5 vs 35.3 ± 10.8 years, respectively; P = .489), body mass index (25.6 ± 4.0 vs 25.1 ± 4.5 kg/m2, respectively; P = .615), or sex (P = .465). There was a significantly increased procedure time (119.3 ± 21.0 vs 99.0 ± 28.6 minutes, respectively; P = .002) and traction time (72.7 ± 21.4 vs 59.0 ± 16.7 minutes, respectively; P = .007) in the early group compared with the late group. Mean postoperative PRO scores significantly improved in both groups compared with preoperative values for all surveys except for the SF-12 mental component summary. No differences were found in PRO score improvements or complication rates between the early and late groups. Conclusion:The total procedure time and traction time decrease after a surgeon's first 30 hip arthroscopic surgery cases for FAI and labral tears, but patient outcomes can similarly improve regardless of surgeon experience in the early part of his or her career

Paper Core Feeder System

Paragon Films has always strived to increase productivity and decrease waist within their company. The plant located in Union Gap, Washington currently has two production lines operating 24/7 managed by 2 to 3 people. The heavy line produces 5000 to 10000 revolutions per roll. This production line has a three part system that automatically feeds the paper cores to the spool shafts to roll the films. Therefore, the employees during that shift do not have to worry about filling up the bin very often. On the other hand, the second production line, which produces the hand films, does not have a system that can feed paper cores to the spool shaft requiring more constant attention by the employees. The drive of this project was to design and manufacture a similar Core Feeder that would automatically feed the cores to the table. This design had size restriction due to the limited space beside the production line but would still manage to improve productivity in the plant. The Core Feeder System will allow employees to fill the bin with more than 200 and only be revisited every couple hours

Rank diversity of languages: Generic behavior in computational linguistics

Statistical studies of languages have focused on the rank-frequency distribution of words. Instead, we introduce here a measure of how word ranks change in time and call this distribution \emph{rank diversity}. We calculate this diversity for books published in six European languages since 1800, and find that it follows a universal lognormal distribution. Based on the mean and standard deviation associated with the lognormal distribution, we define three different word regimes of languages: "heads" consist of words which almost do not change their rank in time, "bodies" are words of general use, while "tails" are comprised by context-specific words and vary their rank considerably in time. The heads and bodies reflect the size of language cores identified by linguists for basic communication. We propose a Gaussian random walk model which reproduces the rank variation of words in time and thus the diversity. Rank diversity of words can be understood as the result of random variations in rank, where the size of the variation depends on the rank itself. We find that the core size is similar for all languages studied

El agua un problema de indole internacional

At present, the problem of the preservation and water consumption is considered as one of the central themes of the century. Indeed, water scarcity, in various regions of the world, has become a threat to the world today. For this reason, our purpose with this topic is to explain the magnitude of the problem, showing the impact on the planet. Thus, the research method used was through numerous media sources, as well as expert opinions. Also, we rely on specific statistical data to support our arguments. Thus, we cover the main regions of the world such as Africa, Middle East, Asia, among others, to present relevant and important examples that demonstrate the magnitude of the problem of water consumption. We also use forward-looking statements to support the possible consequences that this problem could detonate if maintained. In this way, we would show the problems associated with water scarcity around the world, showing how it reaches millions of people, as well as the political implications in the future. In conclusion, through this research, we will demonstrate that the water problem is a problem that concerns the whole world, and if we don’t find a solution, dire consequences could happen .En la actualidad, el problema sobre la preservación y consumo del agua es considerado como uno de los temas centrales del siglo XXI. En efecto, la escasez de agua en diversas regiones del mundo, se ha vuelto una amenaza para el mundo actual. Por esta razón, nuestro propósito con este tema es tratar de explicar la magnitud del problema, mostrando el impacto que acarrea en el planeta. De esta manera, el método de investigación utilizado fue a través de numerosas fuentes periodísticas, así como también de opiniones de expertos. Asimismo, nos basamos en datos estadísticos específicos para fundamentar nuestros argumentos. Así, logramos abarcar las principales regiones del mundo como África, Medio Oriente, Asia, entre otros, para presentar ejemplos pertinentes e importantes, que demuestren la magnitud del problema sobre el consumo del agua. Además, utilizamos proyecciones a futuro para sustentar las posibles consecuencias que este problema traería si se mantiene. Logramos, de esta manera, evidenciar los problemas que conlleva la escasez de agua alrededor del mundo, demostrando como perjudica a millones de personas, así como también las repercusiones que tiene a nivel político y en el porvenir. En conclusión, a través de esta investigación se demuestra, sin lugar a dudas, que el problema del agua es un problema que concierne a toda la población mundial, afecta en diversos aspectos, y, si no se lo logra remediar, terribles consecuencias podrían suceder