Adaptive Tesselation CMAC

An ndaptive tessellation variant of the CMAC architecture is introduced. Adaptive tessellation is an error-based scheme for distributing input representations. Simulations show that the new network outperforms the original CMAC at a vnriety of learning tasks, including learning the inverse kinematics of a two-link arm.Office of Naval Research (N00014-92-J-4015, N00014-91-J-4100); National Science Foundation (IRI-90-00530); Boston University Presidential Graduate Fellowshi

Global Motion Configuration Can Override Local Motion Contrast

How is the perceived direction of motion of a target affected by the motion of multiple surrounding regions? Observers viewed displays consisting of three nested regions, a circular target region surrounded by two concentric annuli, each containing coherently moving dots. The observers' task was to estimate the direction of motion of the dots in the central region. By itself, motion in either annulus can alter this estimate, producing a contrast effect whereby the perceived direction of the centre is biased away from the direction of motion of the annulus. In combination, the outer annulus dominated the inner in its effect on the target's motion. This result suggests that local operators, such as antagonistic centre-surround mechanisms for motion direction, are in themselves insufficient to explain relative motion effects.Office of Naval Research (N00014-92-J-4015, N00014-91-J-4100, N00014-94-J-0597); National Science Foundation (IRI- 90-00530); Air Force Office of Scientific Research (F49620-92-J-0334

The Impact of Affinity on World Economic Integration: The Case of Japanese Foreign Direct Investment

This paper finds that a country’s affinity with a foreign country has a positive effect on foreign direct investment flows from it to that country, by analyzing Japanese foreign direct investment outflows during the period of 1995 to 2009. A rise in affinity between countries is thought to enhance their mutual trust and as a result lower the transaction costs of economic activities between them, thereby helping to promote bilateral foreign direct investment flows. These findings imply that a rise in affinity among countries is likely to facilitate international economic integration.JEL Classification Codes: F2Embargo Period 24 monthshttp://www.grips.ac.jp/list/jp/facultyinfo/chey_hyoung-kyu

Neural Dynamics of Motion Processing and Speed Discrimination

A neural network model of visual motion perception and speed discrimination is presented. The model shows how a distributed population code of speed tuning, that realizes a size-speed correlation, can be derived from the simplest mechanisms whereby activations of multiple spatially short-range filters of different size are transformed into speed-tuned cell responses. These mechanisms use transient cell responses to moving stimuli, output thresholds that covary with filter size, and competition. These mechanisms are proposed to occur in the Vl→7 MT cortical processing stream. The model reproduces empirically derived speed discrimination curves and simulates data showing how visual speed perception and discrimination can be affected by stimulus contrast, duration, dot density and spatial frequency. Model motion mechanisms are analogous to mechanisms that have been used to model 3-D form and figure-ground perception. The model forms the front end of a larger motion processing system that has been used to simulate how global motion capture occurs, and how spatial attention is drawn to moving forms. It provides a computational foundation for an emerging neural theory of 3-D form and motion perception.Office of Naval Research (N00014-92-J-4015, N00014-91-J-4100, N00014-95-1-0657, N00014-95-1-0409, N00014-94-1-0597, N00014-95-1-0409); Air Force Office of Scientific Research (F49620-92-J-0499); National Science Foundation (IRI-90-00530

Neural Dynamics of Motion Grouping: From Aperture Ambiguity to Object Speed and Direction

A neural network model of visual motion perception and speed discrimination is developed to simulate data concerning the conditions under which components of moving stimuli cohere or not into a global direction of motion, as in barberpole and plaid patterns (both Type 1 and Type 2). The model also simulates how the perceived speed of lines moving in a prescribed direction depends upon their orientation, length, duration, and contrast. Motion direction and speed both emerge as part of an interactive motion grouping or segmentation process. The model proposes a solution to the global aperture problem by showing how information from feature tracking points, namely locations from which unambiguous motion directions can be computed, can propagate to ambiguous motion direction points, and capture the motion signals there. The model does this without computing intersections of constraints or parallel Fourier and non-Fourier pathways. Instead, the model uses orientationally-unselective cell responses to activate directionally-tuned transient cells. These transient cells, in turn, activate spatially short-range filters and competitive mechanisms over multiple spatial scales to generate speed-tuned and directionally-tuned cells. Spatially long-range filters and top-down feedback from grouping cells are then used to track motion of featural points and to select and propagate correct motion directions to ambiguous motion points. Top-down grouping can also prime the system to attend a particular motion direction. The model hereby links low-level automatic motion processing with attention-based motion processing. Homologs of model mechanisms have been used in models of other brain systems to simulate data about visual grouping, figure-ground separation, and speech perception. Earlier versions of the model have simulated data about short-range and long-range apparent motion, second-order motion, and the effects of parvocellular and magnocellular LGN lesions on motion perception.Office of Naval Research (N00014-920J-4015, N00014-91-J-4100, N00014-95-1-0657, N00014-95-1-0409, N00014-91-J-0597); Air Force Office of Scientific Research (F4620-92-J-0225, F49620-92-J-0499); National Science Foundation (IRI-90-00530

A Neural Model of Biased Oscillations in Aplysia Head-Waving Behavior

A long-term bias in the exploratory head-waving behavior of Aplysia can be induced using bright lights as an aversive stimulus: coupling onset of the lights with head movements to one side results in a bias away from that side (Cook & Carew, 1986). This bias has been interpreted as a form of operant conditioning, and has previously been simulated with a neural network model based on associative synaptic facilitation (Raymond, Baxter, Buonomano, & Byrne, 1992). In this article we simulate the head-waving behavior using a recurrent gated dipole, a nonlinear dynamical neural model that has previously been used to explain various data including oscillatory behavior in biological pacemakers. Within the recurrent gated dipole, two channels operate antagonistically to generate oscillations, which drive the side-to-side head waving. The frequency of oscillations depends on transmitter mobilization dynamics, which exhibit both short- and long-term adaptation. We assume that light onset results in a nonspecific increase in arousal to both channels of the dipole. Repeated pairing of arousal increments with activation of one channel (the "reinforced" channel) of the dipole leads to a bias in transmitter dynamics, which causes the oscillation to last a shorter time on the reinforced channel than on the non-reinforced channel. Our model provides a parsimonious explanation of the observed behavior, and it avoids some of the unexpected results obtained with the Raymond et al. model. In addition, our model makes predictions concerning the rate of onset and extinction of the biases, and it suggests new lines of experimentation to test the nature of the head-waving behavior.Office of Naval Research (N00014-92-J-4015, N00014-91-J-4100, N0014-92-J-1309); Air Force Office of Scientific Research (F49620-92-J-0499); A.P. Sloan Foundation (BR-3122

The role of antiphase boundaries during ion sputtering and solid phase epitaxy of Si(001)

The Si(001) surface morphology during ion sputtering at elevated temperatures and solid phase epitaxy following ion sputtering at room temperature has been investigated using scanning tunneling microscopy. Two types of antiphase boundaries form on Si(001) surfaces during ion sputtering and solid phase epitaxy. One type of antiphase boundary, the AP2 antiphase boundary, contributes to the surface roughening. AP2 antiphase boundaries are stable up to 973K, and ion sputtering and solid phase epitaxy performed at 973K result in atomically flat Si(001) surfaces.Comment: 16 pages, 4 figures, to be published in Surface Scienc

New records of florivory on dipterocarp flowers

Peer reviewedPreprin

The Relationship Between Adverse Childhood Experiences and Social Communication: A Survey Study

Speech-language pathologists work with individuals who have experienced various levels of adversity. The title of this thesis is The Relationship between Adverse Childhood Experiences (ACEs) and Social Communication: A Survey study. The researcher, Chey Robertson, from the communication sciences and disorders program from a university in the Midwest investigated the relationship between ACEs and social communication such as social cognition, social interaction, and pragmatics. ACEs includes physical, emotional, and sexual abuse, and physical and emotional neglect. ACEs also includes household dysfunction such as a household member with mental illness, witnessing domestic violence, incarceration of a household member, household member who abuses drugs or alcohol, and separation of parents. The aim of this study is to focus on the association between ACEs and social communication as it is important for SLPs, other health professionals, and educators to consider all the factors that might influence an individual’s ability or inability to communicate effectively. A survey was used to collect information about participants’ ACEs and social communication. The survey was disbursed to college students at a Midwest university from October 2018 to January 2019. The survey included an ACE and social communication questionnaire. An analysis of the data focused on a correlation between the total ACE score and social communication (social cognition, social interaction, and pragmatics). T-tests were also run to compare significant ACE scores and social communication with less significant ACE scores and social communication. Furthermore, t-tests were run to compare each ACE with social communication. The results of the study partially support the hypothesis as a weak relationship was found between the total number of ACEs individuals were exposed to and social communication. Additionally, a significant difference was found when comparing individuals who had experienced ACEs (specifically physical abuse, sexual abuse, emotional neglect, and/or a household member with a mental illness, such as depression, or suicidal ideation) and their social communication (social cognition, social interaction, and pragmatics) difficulties

Cultural acclimatisation: Foreign students studying in a private educational institution in Singapore

This Portfolio aims to examine the problems of acclimatisation and coping strategies of such foreign students. A sample of tweleve students was chosen from Chinese students studying at one private educational institution in Singapore. Drawing on the findings of Furnham (1997) and Murphy-Lejenne (2002), among others, the present study looks at the reasons why the participants decided to travel overseas, why they chose Singapore as their destination, what problems they encountered while here, and how they coped with the problems. They were also asked what specific problems they encountered with the schools they enrolled in. It is the contention of the present study that school has a major influenceon their overall acclimatisation. Suggestions were sought from the participants on ways they thought the school could help make their stay here more successful The in-depth interviews found that the main problem encountered by the Chinese students were with accommodation, student agents, school, language, and the :attitude of the local populance towards them. To cope with their problem;, they relied on friends, and family for support and information, and used modern technology for communication. They expected the school to help them find suitable accommodation and practise higher standards of service. The present study concludes with recommendations for further actions needed by schools and government and areas for future research