Age Related Decrements in Steering Control: The Effects of Landmark and Optical Flow Information

This study examined age related decrements in the use of optical flow and landmark information for the control of steering. Older and younger drivers viewed computer generated displays simulating vehicle motion through a random dot ground plane scene. The horizontal position of the driver was perturbed according a sum of sines function and the driver had to keep steering straight (resembling the task of steering a car on a gusty day). On half the trials, landmark information was presented by color coding one of the dots on the ground plane. Overall, older drivers showed greater steering error magnitude (RMS error) than younger drivers. Unlike the younger drivers, the older drivers showed no reduction in steering errors when landmark information was present. These results suggest that older drivers are more reliant on optical flow information for controlling a vehicle and have a reduced ability to use alternative sources of information, such as landmarks, for steering control

Interpreting the seasonal cycles of atmospheric oxygen and carbon dioxide concentrations at American Samoa Observatory

We present seven years of atmospheric O2/N2 ratio and CO2 concentration data measured from flask samples collected at American Samoa. These data are unusual, exhibiting higher short-term variability, and seasonal cycles not in phase with other sampling stations. The unique nature of atmospheric data from Samoa has been noted previously from measurements of CO2, methyl chloroform, and ozone. With our O2 data, we observe greater magnitude in the short-term variability, but, in contrast, no clear seasonal pattern to this variability. This we attribute to significant regional sources and sinks existing for O2 in both hemispheres, and a dependence on both the latitudinal and altitudinal origins of air masses. We also hypothesize that some samples exhibit a component of "older" air, demonstrating recirculation of air within the tropics. Our findings could be used to help constrain atmospheric transport models which are not well characterized in tropical regions

On the question of whether to model or measure the levels of RF energy from mobile phones into the head

On the question of whether to model or measure the levels of RF energy from mobile phones into the hea

A study of head worn jewellery, mobile phone RF energy and the effect of differing issue types on rates of absorption

This paper investigates the effects of metallic jewellery on the SAR in progressively more complex models of the human head, using the FDTD method. A halfwavelength dipole excitation at 1800MHz is positioned in front of the head to represent a cellular enabled personal communication device. FDTD results show good agreement with DASY4 measurements. Metallic jewellery has been found to increase SAR in the head and the levels of SAR depends on the shape and the electrical properties of the tissues in the head. A metallic pin was found to increase the SAR averaged over 1g by 16.0 times in a homogeneous cubic head, whereas, the same pin increased the 1g SAR in an anatomically realistic head by a factor of only 2.5. The results shown in this paper are for a metallic pin that may represent a facial piercing, a section of metallic spectacles or a microphone for a hands free kit

Professor Jim James ... a great researcher and motivator in the field of antennas

This paper is dedicated to Professor Jim James. It is a celebration of his life, career and world renowned research contribution to the engineering community. Jim was eminent for his pioneering research contributions to the fundamental understanding of radiation mechanisms in printed patch and small antennas including seminal achievements, both theoretical and in terms of demonstrated practical applications, in communications, radar and medical electronics. The paper includes a brief summary of his research. Details will also be included on some of his latest work involving low SAR material coated mobile handset antennas

Broad Balmer Wings in BA Hyper/Supergiants Distorted by Diffuse Interstellar Bands: Five Examples in the 30 Doradus Region from the VLT-FLAMES Tarantula Survey

Extremely broad emission wings at Hβ and Hα have been found in VLT-FLAMES Tarantula Survey data for five very luminous BA supergiants in or near 30 Doradus in the Large Magellanic Cloud. The profiles of both lines are extremely asymmetrical, which we have found to be caused by very broad diffuse interstellar bands (DIBs) in the longward wing of Hβ and the shortward wing of Hα. These DIBs are well known to interstellar but not to many stellar specialists, so that the asymmetries may be mistaken for intrinsic features. The broad emission wings are generally ascribed to electron scattering, although we note difficulties for that interpretation in some objects. Such profiles are known in some Galactic hyper/supergiants and are also seen in both active and quiescent Luminous Blue Variables (LBVs). No prior or current LBV activity is known in these 30 Dor stars, although a generic relationship to LBVs is not excluded; subject to further observational and theoretical investigation, it is possible that these very luminous supergiants are approaching the LBV stage for the first time. Their locations in the HRD and presumed evolutionary tracks are consistent with that possibility. The available evidence for spectroscopic variations of these objects is reviewed, while recent photometric monitoring does not reveal variability. A search for circumstellar nebulae has been conducted, with an indeterminate result for one of them

A study of the validation of RF energy specific absorption rates for simulations of anatomically correct head FDTD simulations and truncated DASY4 standard equipment measurements

This paper presents results of a study concerning the modification of a generic DASY4 twin phantom SAR kit (designed for measurements of mobile phones held to the ear) to facilitate SAR measurements of personal data assistant mobile communications equipment held in front of the face. The source used was a half wavelength dipole illuminating a SAM phantom face. Two half heads bonded together were used and the effect of removing the rearmost part of the phantom head were considered. Results from FDTD simulations show the effects of the modification. When a 60mm section is removed from the back of the head, the 1g and 10g SAR values at 900MHz deviate by about 2.4% and at 1800MHz by about 0.3% from the values obtained with the full head

Associations Between MRI-Assessed Locus Coeruleus Integrity and Cortical Gray Matter Microstructure

The locus coeruleus (LC) is one of the earliest sites of tau pathology, making it a key structure in early Alzheimer's disease (AD) progression. As the primary source of norepinephrine for the brain, reduced LC integrity may have negative consequences for brain health, yet macrostructural brain measures (e.g. cortical thickness) may not be sensitive to early stages of neurodegeneration. We therefore examined whether LC integrity was associated with differences in cortical gray matter microstructure among 435 men (mean age = 67.5; range = 62-71.7). LC structural integrity was indexed by contrast-to-noise ratio (LCCNR) from a neuromelanin-sensitive MRI scan. Restriction spectrum imaging (RSI), an advanced multi-shell diffusion technique, was used to characterize cortical microstructure, modeling total diffusion in restricted, hindered, and free water compartments. Higher LCCNR (greater integrity) was associated with higher hindered and lower free water diffusion in multiple cortical regions. In contrast, no associations between LCCNR and cortical thickness survived correction. Results suggest lower LC integrity is associated with patterns of cortical microstructure that may reflect a reduction in cytoarchitectural barriers due to broader neurodegenerative processes. These findings highlight the potential utility for LC imaging and advanced diffusion measures of cortical microstructure in assessing brain health and early identification of neurodegenerative processes

Professor Jim James...a great researcher and motivator in the field of antennas

This paper is dedicated to Professor Jim James. It is a celebration of his life, career and world renowned research contribution to the engineering community. Jim was eminent for his pioneering research contributions to the fundamental understanding of radiation mechanisms in printed patch and small antennas including seminal achievements, both theoretical and in terms of demonstrated practical applications, in communications, radar and medical electronics. The paper includes a brief summary of his research. Details will also be included on some of his latest work involving low SAR material coated mobile handset antennas

Higher cortical thickness/volume in Alzheimer’s-related regions: protective factor or risk factor?

Some evidence suggests a biphasic pattern of changes in cortical thickness wherein higher, rather than lower, thickness is associated with very early Alzheimer's disease (AD) pathology. We examined whether integrating information from AD brain signatures based on mean diffusivity (MD) can aid in the interpretation of cortical thickness/volume as a risk factor for future AD-related changes. Participants were 572 men in the Vietnam Era Twin Study of Aging who were cognitively unimpaired at baseline (mean age = 56 years; range = 51-60). Individuals with both high thickness/volume signatures and high MD signatures at baseline had lower cortical thickness/volume in AD signature regions and lower episodic memory performance 12 years later compared to those with high thickness/volume and low MD signatures at baseline. Groups did not differ in level of young adult cognitive reserve. Our findings are in line with a biphasic model in which increased cortical thickness may precede future decline and establish the value of examining cortical MD alongside cortical thickness to identify subgroups with differential risk for poorer brain and cognitive outcomes