The attenuation surface for contrast sensitivity has the form of a witch’s hat within the central visual field

Over the full visual field, contrast sensitivity is fairly well described by a linear decline in log sensitivity as a function of eccentricity (expressed in grating cycles). However, many psychophysical studies of spatial visual function concentrate on the central ±4.5 deg (or so) of the visual field. As the details of the variation in sensitivity have not been well documented in this region we did so for small patches of target contrast at several spatial frequencies (0.7–4 c/deg), meridians (horizontal, vertical, and oblique), orientations (horizontal, vertical, and oblique), and eccentricities (0–18 cycles). To reduce the potential effects of stimulus uncertainty, circular markers surrounded the targets. Our analysis shows that the decline in binocular log sensitivity within the central visual field is bilinear: The initial decline is steep, whereas the later decline is shallow and much closer to the classical results. The bilinear decline was approximately symmetrical in the horizontal meridian and declined most steeply in the superior visual field. Further analyses showed our results to be scale-invariant and that this property could not be predicted from cone densities. We used the results from the cardinal meridians to radially interpolate an attenuation surface with the shape of a witch's hat that provided good predictions for the results from the oblique meridians. The witch's hat provides a convenient starting point from which to build models of contrast sensitivity, including those designed to investigate signal summation and neuronal convergence of the image contrast signal. Finally, we provide Matlab code for constructing the witch's hat.

Volunteering for success:mentoring as a form of student volunteering

Previous studies into student volunteering have shown how formally organized volunteering activities have social, economic and practical benefits for student volunteers and the recipients of their volunteerism (Egerton, 2002; Vernon & Foster, 2002); moreover student volunteering provides the means by which undergraduates are able to acquire and hone transferable skills sought by employers following graduation (Eldridge & Wilson, 2003; Norris et al, 2006). Within the UK Higher Education Sector, a popular mechanism for accessing volunteering is through formally organized student mentoring programmes whereby more ‘senior’ students volunteer to mentor less experienced undergraduates through a particular phase of their academic careers, including the transition from school or college to university. The value of student mentoring as a pedagogical tool within Higher Education is reflected in the literature (see for example, Bargh & Schul, 1980, Hartman,1990, Woodd, 1997). However, from a volunteering perspective, one of the key issues relates to the generally accepted conceptualisation of volunteering as a formally organized activity, that is un-coerced and for which there is no payment (Davis Smith, 1992, 1998; Sheard, 1995). Although the majority of student mentoring programs discussed in the paper are unpaid and voluntary in nature, in a small number of institutions some of the mentoring programs offered to students provide a minimum wage for mentors. From an ethical perspective, such payments may cause difficulties when considering potential mentors’ motivations and reasons for participating in the program. Additionally, institutions usually only have one or two paid mentoring programs running alongside several voluntary programmes – sometimes resulting in an over-subscription for places as paid mentors to the detriment of unpaid programs. Furthermore, from an institutional perspective, student mentoring presents a set of particular ethical problems reflecting issues around ‘matching’ mentors and mentees in terms of gender, race, ethnicity and religion. This is found to be the case in some ‘targeted’ mentoring programs whereby a particular demographic group of students are offered access to mentoring in an attempt to improve their chances of academic success. This paper provides a comparative analysis of the experiences and perceptions of mentors and mentees participating in a wide-range of different mentoring programs. It also analyzes the institutional challenges and benefits associated with managing large scale student volunteering programs. In doing so the paper adds to third sector literature by critiquing the distinctive issues surrounding student volunteering and by discussing, in-depth, the management of large groups of student volunteers. From a public policy perspective, the economic, educational, vocational and social outcomes of student volunteering make this an important subject meriting investigation. Little is known about the mentoring experiences of student volunteers with regards to the ‘added value’ of participating in campus-based volunteering activities. Furthermore, in light of the current economic downturn, by drawing attention to the contribution that student volunteering plays in equipping undergraduates with transferable ‘employability’ related skills and competencies (Andrews & Higson, 2008), this paper makes an important contribution to current educational and political debates. In addition to providing the opportunity for students to acquire key transferable skills, the findings suggest that mentoring encourages students to volunteer in other areas of university and community life. The paper concludes by arguing that student mentoring provides a valuable learning experience for student volunteer mentors and for the student and pupil mentees with whom they are placed.

Can the Q Link Ally,® a form of sympathetic resonance technology (SRT™), sttenuate scute mobile phone-related changes to neural function?

OBJECTIVES: Exposure to active mobile phones (MP) has been shown to affect human neural function as shown by the electroencephalogram (EEG). Although it has not been determined whether such effects are harmful, a number of devices have been developed that attempt to minimize these MP-related effects. One such device, the Q Link Ally® (QL; Clarus Products, International, L.L.C., San Rafael, CA), is argued to affect the human organism in such a way as to attenuate the effect of MPs. The present pilot study was designed to determine whether there is any indication that QL does alter MP-related effects on the human EEG. DESIGN: Twenty-four (24) subjects participated in a single-blind, fully counterbalanced crossover design in which subjects' resting EEG and phase-locked neural responses to auditory stimuli were assessed under conditions of either active MP or active MP plus QL. RESULTS: The addition of QL to the MP condition increased resting EEG in the gamma range and did so as a function of exposure duration, and it attenuated MP-related effects in the delta and alpha range (at trend-level). The addition of the QL also affected phase-locked neural responses, with a laterality reversal in the alpha range and an alteration to changes over time in the delta range, a reduction of the MP-related beta decrease over time at fronto-posterior sites, and a global reduction in the gamma range that increased as a function of exposure duration. No unambiguous relations were found between these changes and either performance or psychologic state. CONCLUSIONS: This pilot study suggests that the addition of the QL to active MP-exposure does affect neural function in humans, altering both resting EEG patterns and the evoked neural response to auditory stimuli, and that there is a tendency for some MP-related changes to the EEG to be attenuated by the QL.