The effect of background spatial contrast on electroretinographic responses in the human retina

AbstractThe electroretinogram (ERG) was obtained to contrast modulation (CM). This stimulus is a product of temporal modulation of the contrast of a spatial sinusoid at constant mean luminance. Mean contrast (10–40%), and modulation depth (25–1.0) were modulated at 7.5Hz to record the pattern electroretinogram (PERG). The spatial pattern was a foveally fixated grating pattern with sinusoidal luminance profile with spatial frequency of 4.6c/deg. CM resulted in significant first and second harmonic ERG responses. First harmonic amplitude increases then flattens as a function of mean contrast with ΔC=constant, while the second harmonic response remains unaffected by mean contrast. Apparently the first harmonic represents summed signals of local luminance responses arising from on and off neurons. Mean spatial contrast signals modulate preganglionic local luminance responses

Menelaus relation and Fay's trisecant formula are associativity equations

It is shown that the celebrated Menelaus relation and Fay's trisecant formula similar to the WDVV equation are associativity conditions for structure constants of certain three-dimensional algebra.Comment: Talk given at the Conference " Mathematics and Physics of Solitons and Integrable Systems", Dijon, 28.6-2.7, 2009. Minor misprints correcte

Service Learning: Bringing The Business Classroom To Life

While service-learning may be easily incorporated into medical or legal fields, this type of active learning generally has not been historically integrated into any discipline within the business curriculum. This is unfortunate, as the utilization of business students in not-for-profit environments can provide a triple-win scenario:  the students receive an enriched learning experience, as they likely will confront opportunities at the entry level that are not generally experienced until the middle-management level; the administrators at the not-for-profit have access to business students with skills that are necessary but typically expensive to acquire; and the constituents served by the organization are enriched by having improved delivery or efficiency of service.  Within this paper, we will discuss the service-learning environment and will then detail a project we have worked on in a service-learning-oriented class, with the hope that others may use our experience to facilitate their own service-learning projects as students or within the context of a class

Completely positive multipliers of quantum groups

We show that any completely positive multiplier of the convolution algebra of the dual of an operator algebraic quantum group \G (either a locally compact quantum group, or a quantum group coming from a modular or manageable multiplicative unitary) is induced in a canonical fashion by a unitary corepresentation of \G. It follows that there is an order bijection between the completely positive multipliers of L^1(\G) and the positive functionals on the universal quantum group C_0^u(\G). We provide a direct link between the Junge, Neufang, Ruan representation result and the representing element of a multiplier, and use this to show that their representation map is always weak$^*$-weak$^*$-continuous.Comment: 18 pages; major rewrit

1976: Abilene Christian College Bible Lectures - Full Text

FREEDOM IN CHRIST Being the Abilene Christian College Annual Bible Lectures 1976 Published by ABILENE CHRISTIAN COLLEGE Book Store ACC Station Abilene, Texas 7960

Menelaus' theorem, Clifford configurations and inversive geometry of the Schwarzian KP hierarchy

It is shown that the integrable discrete Schwarzian KP (dSKP) equation which constitutes an algebraic superposition formula associated with, for instance, the Schwarzian KP hierarchy, the classical Darboux transformation and quasi-conformal mappings encapsulates nothing but a fundamental theorem of ancient Greek geometry. Thus, it is demonstrated that the connection with Menelaus' theorem and, more generally, Clifford configurations renders the dSKP equation a natural object of inversive geometry on the plane. The geometric and algebraic integrability of dSKP lattices and their reductions to lattices of Menelaus-Darboux, Schwarzian KdV, Schwarzian Boussinesq and Schramm type is discussed. The dSKP and discrete Schwarzian Boussinesq equations are shown to represent discretizations of families of quasi-conformal mappings.Comment: 26 pages, 9 figure

Prostaglandin E2 Prevents Hyperosmolar-Induced Human Mast Cell Activation through Prostanoid Receptors EP2 and EP4

Background: Mast cells play a critical role in allergic and inflammatory diseases, including exercise-induced bronchoconstriction (EIB) in asthma. The mechanism underlying EIB is probably related to increased airway fluid osmolarity that activates mast cells to the release inflammatory mediators. These mediators then act on bronchial smooth muscle to cause bronchoconstriction. In parallel, protective substances such as prostaglandin E2 (PGE2) are probably also released and could explain the refractory period observed in patients with EIB. Objective: This study aimed to evaluate the protective effect of PGE2 on osmotically activated mast cells, as a model of exercise-induced bronchoconstriction. Methods: We used LAD2, HMC-1, CD34-positive, and human lung mast cell lines. Cells underwent a mannitol challenge, and the effects of PGE2 and prostanoid receptor (EP) antagonists for EP1-4 were assayed on the activated mast cells. Beta-hexosaminidase release, protein phosphorylation, and calcium mobilization were assessed. Results: Mannitol both induced mast cell degranulation and activated phosphatidyl inositide 3-kinase and mitogen-activated protein kinase (MAPK) pathways, thereby causing de novo eicosanoid and cytokine synthesis. The addition of PGE2 significantly reduced mannitol-induced degranulation through EP2 and EP4 receptors, as measured by beta-hexosaminidase release, and consequently calcium influx. Extracellular-signal-regulated kinase 1/2, c-Jun N-terminal kinase, and p38 phosphorylation were diminished when compared with mannitol activation alone. Conclusions:Our data show a protective role for the PGE2 receptors EP2 and EP4 following osmotic changes, through the reduction of human mast cell activity caused by calcium influx impairment and MAP kinase inhibition

Endpoint Estimates for N-dimensional Hardy Operators and Their Commutators

In this paper, it is proved that the higher dimensional Hardy operator is bounded from Hardy space to Lebesgue space. The endpoint estimate for the commutator generated by Hardy operator and (central) BMO function is also discussed.Comment: 8 page

An evaluation of the effectiveness of PROMPT therapy in improving speech production accuracy in six children with cerebral palsy

This study evaluates perceptual changes in speech production accuracy in six children (3 – 11 years) with moderate-to-severe speech impairment associated with cerebral palsy before, during, and after participation in a motor-speech intervention program (Prompts for Restructuring Oral Muscular Phonetic Targets). An A1BCA2 single subject research design was implemented. Subsequent to the baseline phase (phase A1), phase B targeted each participant’s first intervention priority on the PROMPT motor-speech hierarchy. Phase C then targeted one level higher. Weekly speech probes were administered, containing trained and untrained words at the two levels of intervention, plus an additional level that served as a control goal. The speech probes were analysed for motor-speech-movement-parameters and perceptual accuracy. Analysis of the speech probe data showed all participants recorded a statistically significant change. Between phases A1 – B and B – C 6/6 and 4/6participants, respectively, recorded a statistically significant increase in performance level on the motor speech movement patterns targeted during the training of that intervention. The preliminary data presented in this study make a contribution to providing evidence that supports the use of a treatment approach aligned with dynamic systems theory to improve the motor-speech movement patterns and speech production accuracy in children with cerebral palsy