'The last channel': vision at the temporal margin of the field.

The human visual field, on the temporal side, extends to at least 90° from the line of sight. Using a two-alternative forced-choice procedure in which observers are asked to report the direction of motion of a Gabor patch, and taking precautions to exclude unconscious eye movements in the direction of the stimulus, we show that the limiting eccentricity of image-forming vision can be established with precision. There are large, but reliable, individual differences in the limiting eccentricity. The limiting eccentricity exhibits a dependence on log contrast; but it is not reduced when the modulation visible to the rods is attenuated, a result compatible with the histological evidence that the outermost part of the retina exhibits a high density of cones. Our working hypothesis is that only one type of neural channel is present in the far periphery of the retina, a channel that responds to temporally modulated stimuli of low spatial frequency and that is directionally selective.Evelyn Trus

Ground Testing a LWIR Imaging Radiometer for an Upcoming Smallsat Mission

The Compact Infrared Radiometer in Space (CIRiS) mission is envisioned as a calibration laboratory in space to test source viewing order and timing. Furthermore, it demonstrates the use of vertically aligned carbon nanotubes as a very high emissivity source and an uncooled microbolometer. Due to the focus on instrument calibration, this program spends a significant amount of time in the thermal vacuum chamber to attain a good quality ground calibration. The resulting test plan is presented, along with the plan as implemented, and several lessons learned from the process

Revisiting the Rigidly Rotating Magnetosphere model for sigma Ori E. I. Observations and Data Analysis

We have obtained 18 new high-resolution spectropolarimetric observations of the B2Vp star sigma Ori E with both the Narval and ESPaDOnS spectropolarimeters. The aim of these observations is to test, with modern data, the assumptions of the Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki (2005), applied to the specific case of sigma Ori E by Townsend et al. (2005). This model includes a substantially offset dipole magnetic field configuration, and approximately reproduces previous observational variations in longitudinal field strength, photometric brightness, and Halpha emission. We analyze new spectroscopy, including H I, He I, C II, Si III and Fe III lines, confirming the diversity of variability in photospheric lines, as well as the double S-wave variation of circumstellar hydrogen. Using the multiline analysis method of Least-Squares Deconvolution (LSD), new, more precise longitudinal magnetic field measurements reveal a substantial variance between the shapes of the observed and RRM model time-varying field. The phase resolved Stokes V profiles of He I 5876 A and 6678 A lines are fit poorly by synthetic profiles computed from the magnetic topology assumed by Townsend et al. (2005). These results challenge the offset dipole field configuration assumed in the application of the RRM model to sigma Ori E, and indicate that future models of its magnetic field should also include complex, higher-order components.Comment: 13 pages, 8 figures. Accepted for publication in MNRA

Medial longitudinal arch development of school children : The College of Podiatry Annual Conference 2015: meeting abstracts

Background Foot structure is often classified into flat foot, neutral and high arch type based on the variability of the Medial Longitudinal Arch (MLA). To date, the literature provided contrasting evidence on the age when MLA development stabilises in children. The influence of footwear on MLA development is also unknown. Aim This study aims to (i) clarify whether the MLA is still changing in children from age 7 to 9 years old and (ii) explore the relationship between footwear usage and MLA development, using a longitudinal approach. Methods We evaluated the MLA of 111 healthy school children [age = 6.9 (0.3) years] using three parameters [arch index (AI), midfoot peak pressure (PP) and maximum force (MF: % of body weight)] extracted from dynamic foot loading measurements at baseline, 10-month and 22-month follow-up. Information on the type of footwear worn was collected using survey question. Linear mixed modelling was used to test for differences in the MLA over time. Results Insignificant changes in all MLA parameters were observed over time [AI: P = .15; PP: P = .84; MF: P = .91]. When gender was considered, the AI of boys decreased with age [P = .02]. Boys also displayed a flatter MLA than girls at age 6.9 years [AI: mean difference = 0.02 (0.01, 0.04); P = .02]. At baseline, subjects who wore close-toe shoes displayed the lowest MLA overall [AI/PP/MF: P < .05]. Subjects who used slippers when commencing footwear use experienced higher PP than those who wore sandals [mean difference = 31.60 (1.44, 61.75) kPa; post-hoc P = .04]. Discussion and conclusion Our findings suggested that the MLA of children remained stable from 7 to 9 years old, while gender and the type of footwear worn during childhood may influence MLA development. Clinicians may choose to commence therapy when a child presents with painful flexible flat foot at age 7 years, and may discourage younger children from wearing slippers when they commence using footwear

Transfer of Calibration to CubeSat On-board Carbon Nanotube Sources

Calibration of CubeSat and other small payloads presents a variety of challenges including greater susceptibility to the space environment, volume constraints on calibration sources and subsystems, and power constraints on electronics. CIRiS (Compact Infrared Radiometer in Space), built by Ball Aerospace, is a multispectral, thermal infrared, radiometric imaging instrument with on-board calibration system, whose small volume (\u3c 8 cm x 20 cm x 20 cm), weight (\u3c 2 kg) and power (\u3c 9.5 W average, including heaters) are compatible with CubeSat spacecraft, or any application with resource constraints. CIRiS has been integrated to a 6U spacecraft bus for an upcoming mission in Low Earth Orbit (LEO). The primary mission objective is demonstration of new technologies for radiometric imaging and calibration from CubeSats or SmallSats. New technologies on CIRiS include two 1/8 inch thick, flat-panel, high emissivity (e\u3e .9965) carbon nanotube (CNT) blackbody sources and a new model of uncooled microbolometer Focal Plane Array (FPA) with less demanding temperature stabilization requirements than previous versions. Three calibration views are available in space: to 1) deep space 2) an on-board CNT source at a selectable and controlled temperature and 3) an on-board CNT source at the instrument temperature, also controlled. The CIRiS instrument enables on-orbit selection of calibration parameters including source temperatures, viewing sequence, timing and other variables. Variation of these parameters during the mission will enable optimization of radiometric and calibration performance. A campaign of thermal-vacuum (TVAC) testing has been completed on the integrated CIRiS instrument and spacecraft. TVAC operations and testing included calibration transfer from a NIST traceable source to the two on-board CNT sources, exercise of the instrument through operational and survival temperature ranges, and instrument performance characterization. The instrument was intentionally configured in TVAC to emulate the on-orbit thermal configuration, with temperature gradients and thermal transients at levels indicated by modeling of the on-orbit thermal configuration. Performance characterization included measurements of repeatability, reproducibility and signal drift