A Neural Model of Visually Guided Steering, Obstacle Avoidance, and Route Selection

A neural model is developed to explain how humans can approach a goal object on foot while steering around obstacles to avoid collisions in a cluttered environment. The model uses optic flow from a 3D virtual reality environment to determine the position of objects based on motion discotinuities, and computes heading direction, or the direction of self-motion, from global optic flow. The cortical representation of heading interacts with the representations of a goal and obstacles such that the goal acts as an attractor of heading, while obstacles act as repellers. In addition the model maintains fixation on the goal object by generating smooth pursuit eye movements. Eye rotations can distort the optic flow field, complicating heading perception, and the model uses extraretinal signals to correct for this distortion and accurately represent heading. The model explains how motion processing mechanisms in cortical areas MT, MST, and VIP can be used to guide steering. The model quantitatively simulates human psychophysical data about visually-guided steering, obstacle avoidance, and route selection.Air Force Office of Scientific Research (F4960-01-1-0397); National Geospatial-Intelligence Agency (NMA201-01-1-2016); National Science Foundation (NSF SBE-0354378); Office of Naval Research (N00014-01-1-0624

Réflexions critiques en marge des notions d’inclusion et d’exclusion : Différences/différends

L’objectif de ces réflexions critiques en marge des notions d’inclusion et d’exclusion est de mettre en valeur certains types de différences et de différends auxquels les philosophes, les scientifiques, les sociologues, les linguistes, les traducteurs et les écrivains doivent faire face aujourd’hui dans un monde qui est toujours plus dialectique que dialogique. Notre tâche est topologique et typologique ; et notre texte prend aussi en considération certains domaines critiques qui font que tout dis-cours est dis-jonction, dis-location et dis-tance.The aim of these critical reflections in the margins of the notions of inclusion and exclusion is to highlight certain types of differences and disagreements that philosophers, scientists, sociologists, linguists, translators and writers have to deal with today in a world which is still more dialectical than dialogical. Our task is topological and typological ; and our text also takes into consideration some critical domains that link all dis-course with dis-junction, dis-location and dis-tance

A Libel Law Analysis of Media Abuses in Reporting on the Duke Lacrosse Fabricated Rape Charges

The broad outlines of the monumental injustices involved in the Duke lacrosse rape-that-never-happened case are well known. An unethical local prosecutor, Michael B. Nifong, for partisan political reasons, pursued the Duke lacrosse team and ultimately indicted three of its members based almost solely on the accusations of a wholly unreliable, self-proclaimed victim. Nifong received generous support and sustenance from many left-leaning, politically active Duke faculty, an extraordinarily inept (or worse) Duke administration, and almost the entirety of the mainstream media. Ultimately, following a detailed analysis by his office, North Carolina Attorney General Roy A. Cooper publicly excoriated Nifong in concluding that the three students wrongfully accused by a rogue prosecutor were innocent; there had never been any credible evidence to support the charges. Nifong was disbarred and generally disgraced. The Duke lacrosse fabricated rape case has since entered the annals of legal history and will doubtlessly be analogized for decades to come as a modern, reverse Scottsboro Boys epic, with the accused white students being railroaded by an African American victim in cahoots with a race-baiting prosecutor. Indeed, being Nifonged has become synonymous with being railroaded. The authors of Until Proven Innocent, Stuart Taylor, Jr. and K.C. Johnson, have written an exceptionally thorough and riveting account of the Duke lacrosse case that exposes and eviscerates the actions of the multiple complicit actors in this perversion of justice. Many have reviewed this account and universally praised its professionalism. None have questioned its basic conclusions

Fibre composites for high pressure pipeline repairs, in-air and subsea: an overview

In 2001 it was reported that in North America alone, corrosion to the Oil & Gas pipeline distribution network cost approximately $2-3.3 billion per annum with 10% of that cost being associated with actual failure of the pipeline. In addition pipelines are also susceptible to erosion and mechanical damage producing further losses in pipe structural integrity. This results in high maintenance costs, possibility of adverse environmental consequences and the costly interruption to product transportation and distribution. The cost and technical challenges of adequately addressing repair are significant and greatly increase for underwater applications particularly with increasing water depth. It therefore induces the need of searching for alternative repair techniques involving new advanced materials for ease of installation and application against adverse environmental effects in the long run. Fibre composite materials provide excellent advantages over conventional metals in engineering practices for many decades. These advantages make fibre composite suitable candidate for effective repair technology. This paper provides a comprehensive review on the recent development and future prospect of using these materials for in-air and underwater pipeline external repairs. Various aspects of technical knowhow; benefits and shortcomings of the repair considerations are also presented

Alternate Computer Input Device for Individuals with Quadriplegia

This project details the design development of an alternative computer input system that allows a person with quadriplegia to move a computer\u27s cursor and activate left and right click button inputs. After researching and analyzing possible solutions, an end design was chosen that most appropriately satisfied all user requirements and engineering specifications. This final design employs a head mounted Inertial Measurement Unit (IMU) with 9 DoF (Degrees of Freedom) to track head movements and correlate these motions to computer cursor movements. A Sip-Puff Transducer monitors and interprets a user\u27s application of negative and positive air pressure differentials to a vinyl tube as analog voltages, which are then interpreted over time to trigger left and right click events. An Arduino Due microcontroller is used to interpret and process these inputs and send mouse commands to the user\u27s computer via a USB connection. In addition to the sensing hardware, there are two indicator LEDs which display the state of the left and right mouse buttons. There are also two adjustment potentiometers, which can be turned to adjust the sensitivity of the mouse tracking and the sip-puff click sensing window. This system improves upon other alternative computer interfaces by allowing the user to more easily perform complex and non-linear tasks such as file organization and digital painting/drawing. Two accelerometers were initially incorporated into the design to be strapped to the upper arms of the user, and upward and downward accelerations caused by the raising and lowering of each shoulder would have corresponded to the activation of the Control and Shift keys. However, due to issues with program timing and computational complexity, these parts of our design that operated the control and shift keys were abandoned

Physicochemical and crystallographic investigations into the salt formation of two heterocyclic drugs

Salt formation provides a means of altering the physicochemical and resultant biological characteristics of a drug entity without modifying its molecular structure. Many published reviews have indicated the importance of the selection of the most appropriate salt form. This work is an investigation into the salt formation of two heterocyclic drugs. This is done by the physicochemical and the crystallographic studies of 19 high resolution single crystal diffraction studies. The particular targets of the work are the selection of the most appropriate salt forms, investigations into the tautomerism and polymorphism (or pseudopolymorphism) and an understanding of the interactions most likely between these heterocyclic drugs and their specific receptor sites. Section 1 describes the effect of protonation on the absorption of drugs, the rationale for using various salt forms and the resultant effect this has on a number of physicochemical properties of the parent compound. Section 2 is a description of the experimental techniques used in the physicochemical investigations and in crystal structure determination. In Sections 3 and 7, the preparation and characterisation of the salts and modifications of the two heterocyclic drugs, GU and IM is described. In Sections 4 and 8, the physicochemical investigations into the hygroscopicity and solid-state stabilities of the salts of GU and IM is described. Van't Hoff solubility studies are used to determine the enthalpies of solution and where appropriate the relative thermodynamic stabilities of the various phases produced. The structures of 19 of the salts or modifications of GU and IM, together with their packing and hydrogen bonding interactions is described in Sections 5 and 9. Sections 6 and 10 describe the ionisation properties of these molecules. Both the guanidine and imidazole moieties of GU and IM, respectively, are tautomeric, the particular form(s) found in these investigations and the effect of protonation is discussed. The conformations of these structures are discussed and the effect of protonation, especially on the puckering of the piperazine ring, is described