Enumeration in Alzheimer's disease and other late life psychiatric syndromes

Previous studies suggest that visual enumeration is spared in normal aging but impaired in abnormal aging (late stage Alzheimer's disease, AD), raising the task's potential as a marker of dementia. Experiment 1 compared speeded enumeration of 1–9 random dots in early stage AD, vascular dementia (VAD), depression, and age-matched controls. Previous deficits were replicated but they were not specific to AD, with the rate of counting larger numerosities similarly slowed relative to controls by both AD and VAD. Determination of subitizing span was complicated by the surprisingly slower enumeration of one than of two items, especially in AD patients. Experiment 2 showed that AD patients’ relative difficulty with one item persisted with further practice and extended to the enumeration of targets among distractors. However, it was abolished when pattern recognition was possible (enumerating dots on a die). Although an enumeration test is unlikely to help differentiate early AD from other common dementias, the unexpected pattern of patients’ performance challenges current models of enumeration and requires further investigation

From TV to tablets – how the BBC’s onscreen journalism is changing

“I used to say what I did and people would understand. Now people say, ‘what’s that?’” said Amanda Farnsworth, editor of visual journalism at the BBC, during the latest Polis Media Agenda Talk. This article by Polis intern Emma Goodman @EmmaMayAle

The role of antibody in the killing of Pseudomonas aeruginosa by human sera

Antibody plays an important role in the protection against many different infections. Here the role of antibody in the protection against P aeruginosa infection was further investigated. Patients suffering from chronic lung infection with P. aeruginosa can produce antibodies that protect the bacterium from the bactericidal activity of serum. The effect of the removal of these antibodies on the P. aeruginosa population was investigated. One clonal lineage appeared to be eradicated from a patient with a multi-lineage infection. However, the treatment did not promote strain replacement in either patient suggesting that a single strain was able to persist within a specific niche in the lung. The role of antibody in the protection against P. aeruginosa infection by sera from healthy individuals was further investigated. Killing of P. aeruginosa was complement-dependent and in some instances, complement alone was sufficient to elicit killing. P. aeruginosa-specific antibodies enhanced the killing of some strains and blocked the killing of others. Inhibitory antibody was identified in healthy serum, suggesting that healthy individuals can produce inhibitory antibodies without an active infection. The mechanism of inhibitory antibodies is not fully understood. A transposon library was constructed in a strain of P. aeruginosa isolated from a non-cystic fibrosis bronchiectasis patient and used to define the essential genome. This was the first library to be constructed in a multi-drug resistant respiratory isolate and consisted of 577,494 unique mutants. The library can be used as a tool to provide further insight into the mechanism of inhibitory antibodies and has the potential to lead to the development of new treatments and diagnostics for patients with inhibitory antibody

Modelling spherical aberration detection in an analog holographic wavefront sensor

The analog holographic wavefront sensor (AHWFS) is a simple and robust solution to wavefront sensing in turbulent environments. Here, the ability of a photopolymer based AHWFS to detect refractively generated spherical aberration is modelled and verified

Analog holographic wavefront sensor for defocus and spherical aberration measurement recorded in a photopolymer

An analog holographic wavefront sensor (AHWFS), for measurement of low and high order (defocus and spherical aberration) aberration modes has been developed as volume phase holograms in a photopolymer recording medium. This is the first time that high order aberrations such as spherical aberration can be sensed using a volume hologram in a photosensitive medium. Both defocus and spherical aberration were recorded in a multi-mode version of this AHWFS. Refractive elements were used to generate a maximum and minimum phase delay of each aberration which were multiplexed as a set of volume phase holograms in an acrylamide based-photopolymer layer. The single-mode sensors showed a high degree of accuracy in determining various magnitudes of defocus and spherical aberration generated refractively. The multi-mode sensor also exhibited promising measurement characteristics and similar trends to the single-mode sensors were observed. The method of quantifying defocus was improved upon and a brief study into material shrinkage and sensor linearity is presented

Direct multiplexing of low order aberration modes in a photopolymerbased holographic element for analog holographic wavefront sensing

The fabrication of an analog holographic wavefront sensor, capable of detecting the low order defocus aberration, was achieved in an acrylamide-based photopolymer. While other implementations of holographic wavefront sensors have been carried out digitally, this process utilises a recording setup consisting only of conventional refractive elements so the cost and complexity of holographic optical element (HOE) production could be much reduced. A pair of diffraction spots, corresponding to a maximum and minimum amount of defocus, were spatially separated in the detector plane by multiplexing two HOEs with different carrier spatial frequencies. For each wavefront with a known aberration that was introduced during playback of the hologram, the resulting intensity ratio was measured in the expected pair of diffracted spots. A number of HOEs were produced with the diffraction efficiency of the multiplexed elements equalized, for a range of diffraction efficiency strengths, some as low as \u3c5%. These HOEs were used to successfully classify four amounts of the defocus aberration through the observed intensity ratio

Development of an Optical Test Bed for the Fabrication and Characterisation of an Analog Holographic Wavefront Sensor

A new holographic recording setup has been developed for the fabrication of single- and multi-mode photopolymer-based analog holographic wavefront sensors. A second setup has been built and used to characterise the sensor at several wavelengths

Scrutinizing pre- and post-device fabrication properties of atomic layer deposition WS₂ thin films

In this work, we investigate the physical and electrical properties of WS2 thin films grown by a plasma-enhanced atomic layer deposition process, both before and after device fabrication. The WS2 films were deposited on thermally oxidized silicon substrates using the W(NMe2)2(NtBu)2 precursor and a H2S plasma at 450 °C. The WS2 films were approximately 8 nm thick, measured from high-resolution cross-sectional transmission electron imaging, and generally exhibited the desired horizontal basal-plane orientation of the WS2 layers to the SiO2 surface. Hall analysis revealed a p-type behavior with a carrier concentration of 1.31 × 1017 cm−3. Temperature-dependent electrical analysis of circular transfer length method test structures, with Ni/Au contacts, yielded the activation energy (Ea) of both the specific contact resistivity and the WS2 resistivity as 100 and 91 meV, respectively. The similarity of these two values indicates that the characteristics of both are dominated by the temperature dependence of the WS2 hole concentration. Change in the material, such as in sheet resistance, due to device fabrication is attributed to the chemicals and thermal treatments associated with resist spinning and baking, ambient and UV exposure, metal deposition, and metal lift off for contact pad formation.</p