Shift-Free Wide-Angle Optical Thin-Film Metamaterial Notch Filter for Visible Laser Protection Systems

Poster presented at the 2018 Defence and Security Doctoral Symposium.In recent years, the threat to pilots and other transport vehicles has increased through laser striking. This is due to the ease of accessibility and the low cost of ownership for handheld portable lasers. The reports from the Civil Aviation Authority (CAA) and their American counterpart, the Federal Aviation Administration (FAA), have outlined that visible green laser attacks consist of 83-91% of all incidents [1,2]. This can lead to temporary impairment to the human eye, with consequences increasing with exposure time resulting in retinal and photo-chemical eye damage. Additionally, the magnitude of severity is increased and could lead to fatal collisions. Current efforts for laser protection devices consist of traditional thin-film Rugate filters. This technology is well-established, but has it disadvantages related to the angular intolerance, where the transmission spectrum of the protection filter undergoes a continuous blue-shift to shorter wavelengths as angle of the incident beam increases. The optical and transport industry, as well as government defence agencies, have a desired interest in developing a truly wide-angle (up to 60 degree) and shift-free laser protection system, which is the main drive behind this research. Our research employs a new theoretical approach to the problem and presents an anti-laser striking design that can effectively block out a Class 3B 532 nm green laser. The functional response of the filter achieves an optical density (OD) of 1.88+ for all polarisation states over a wide range of angles up to 85 degrees and attains an integrated visual photopic transmission (IVPT) of 61%. The calculated filter colouration is near-natural, experiencing a slight magenta and turquoise hue for the transmission and reflection colouration, respectively. The devices active blocking layer structure is based on a three-dimensional plasmonic nanocomposite metamaterial, with a base element of silver nanoparticles arranged in a crystallographic primitive hexagonal Bravais lattice planar array, surrounded in a host dielectric medium. The active component is sandwiched between a transparent substrate and an anti-reflection coating. The lattice arrangement enables polarisation insensitivity, with a three dimensional array density catering for an increase attenuation.The designed filter has been computationally verified by a full-wave analysis approach using CST Studio software. The optical properties for refractive indices and extinction coefficients for the used materials have been obtained from literature and adjusted to cater for particle sizing.Reference[1] P. Murphy, “Laser Pointer Safety – Latest aviation statistics”, Laserpointersafety.com, 2017. [Online]. Available: http://www.laserpointersafety.com/latest-stats.html. [Accessed: 18- Aug- 2017].[2] “Laser Incidents reported to the UK CAA 2016,” Laser incidents | UK Civil Aviation Authority. [Online]. Available: https://www.caa.co.uk/Data-and-analysis/Safety-and-security/Datasets/Laser-incidents/. [Accessed: 02- Aug- 2017].Knowledge Economy Skills Scholarship (KESS2, Ref: BUK289

The development and validation of a teacher-reported low-level classroom disruption scale (LLCD-S)

Low-level classroom disruption (LLCD) is characterised by pupils swinging on chairs, whispering or fidgeting in class. This paper provides initial data on the development and validation of the teacher-rated Low-Level Classroom Disruption Scale (LLCD-S), with two samples of primary school pupils. Exploratory factor analysis in Study 1 (N= 120) revealed one factor accounting for 61% of the variance; supported by confirmatory factor analysis in Study 2 (N= 274), with one factor accounting for 63% of the variance. Both studies reported high Cronbach’s alpha values of.82 and.93 respectively. The evidence supports LLCD being a unidimensional construct, measured by the eight item LLCD-S. Weak convergence validity was found between the LLCD-S and the Strengths and Difficulties Questionnaire’s (SDQ) externalising behaviours: conduct problems and hyperactivity. This preliminary evidence indicates that LLCD-S is a valid and reliable measure of low-level classroom disruption. Further research is needed to test the utility of the LLCD-S across different levels of education, cultures and as a pupil-reported measure

Evaluation of the significance of polyamines and their oxidases in the aetiology of human cervical carcinoma.

The risk of cancer of the cervix is linked with sexual behaviour. Although infectious agents such as human papillomaviruses (HPVs) are implicated, these alone may be insufficient to induce the disease. We have investigated the potential role of oxidation products of the polyamines spermine and spermidine and the diamine putrescine in seminal plasma (SP) as co-factors in the development of cervical cancer. These amines are oxidised by polyamine oxidase (PAO) and diamine oxidase (DAO) to generate oxygen radicals and hydrogen peroxide, reactive aldehydes and acrolein, which are likely to exert local mutagenic, cytotoxic and immunosuppressive effects in vivo. Using a chemiluminescence assay, we determined the levels of these amines in 187 samples of SP. Spermine plus spermidine, as substrates for PAO, were present in a range equivalent to 0-4.8 mg ml-1 spermine. Putrescine, as a substrate for DAO, was detectable in only 4 of 40 samples assayed (range 0-168 micrograms ml-1) and constitutes a minor component of the oxidisable content of SP. Cervical mucus (126 samples) was assayed for the presence of PAO and DAO. Both enzymes were present in 14.3% of the samples, PAO only in 21.4%, DAO only in 15.1% and neither enzyme in 49.2%. PAO levels ranged from 0 to 0.828 pmol peroxide generated min-1 mg-1 mucus and DAO levels ranged from 0 to 7.0 pmol peroxide generated min-1 mg-1 mucus. These results suggest that sexual activity in the absence of physical barrier contraception may lead to the generation of mutagenic and immunosuppressive polyamine oxidation products within the female genital tract. We thus propose that women with high levels of PAO and/or DAO in their cervical mucus may be at increased risk of cervical cancer, especially if the male partner's SP shows high polyamine levels. HPV infection may synergise with the effects of polyamine oxidation by suppressing apoptosis in keratinocytes carrying potentially oncogenic mutations, leading to the survival and proliferation of transformed cells in the cervix

Young people\u27s views regarding participation in mental health and wellbeing research through social media

Social media is a central component in the lives of many young people, and provides innovative potential to conduct research among this population. Ethical issues around online research have been subject to much debate, yet young people have seldom been consulted to provide a youth perspective and voice. Eight (8) focus groups involving 48 Grade 9 Western Australian secondary school students aged 13-14 years were held in 2012, to investigate how young people perceive the feasibility and acceptability of social media when used as a research tool to investigate various issues relevant to their mental health and wellbeing. Whilst young people recognise many benefits of researchers using social media in this way, such as its relevance, innovation and accessibility, there were salient issues of privacy, consent, and practicality that require careful negotiation. There is a need for continued exploration and scientific debate of the moral and ethical implications of using social media for research, to help ensure this is employed in an appropriate and effective way that is respectful of and sensitive to the needs and views of young people

Sex Ratio Bias and Extinction Risk in an Isolated Population of Tuatara (\u3ci\u3eSphenodon Punctatus\u3c/i\u3e)

Understanding the mechanisms underlying population declines is critical for preventing the extinction of endangered populations. Positive feedbacks can hasten the process of collapse and create an ‘extinction vortex,’ particularly in small, isolated populations. We provide a case study of a male-biased sex ratio creating the conditions for extinction in a natural population of tuatara (Sphenodon punctatus) on North Brother Island in the Cook Strait of New Zealand. We combine data from long term mark-recapture surveys, updated model estimates of hatchling sex ratio, and population viability modeling to measure the impacts of sex ratio skew. Results from the mark-recapture surveys show an increasing decline in the percentage of females in the adult tuatara population. Our monitoring reveals compounding impacts on female fitness through reductions in female body condition, fecundity, and survival as the male-bias in the population has increased. Additionally, we find that current nest temperatures are likely to result in more male than female hatchlings, owing to the pattern of temperature-dependent sex determination in tuatara where males hatch at warmer temperatures. Anthropogenic climate change worsens the situation for this isolated population, as projected temperature increases for New Zealand are expected to further skew the hatchling sex ratio towards males. Population viability models predict that without management intervention or an evolutionary response, the population will ultimately become entirely comprised of males and functionally extinct. Our study demonstrates that sex ratio bias can be an underappreciated threat to population viability, particularly in populations of long-lived organisms that appear numerically stable

Cellular glutathione as a determinant of the sensitivity of colorectal tumour cell-lines to ZD2767 antibody-directed enzyme prodrug therapy (ADEPT)

ZD2767P, a nitrogen mustard glutamate prodrug, is currently being evaluated in Phase 1 clinical trials of antibody directed enzyme prodrug therapy (ADEPT). There was no significant relationship between basal glutathione (GSH) concentration and sensitivity to ZD2767P + carboxpeptidase G2 (CPG2) in colorectal tumour cell-lines. Depletion of intracellular GSH using buthionine sulfoximine (BSO) resulted in only a modest potentiation of ZD2767P + CPG2 activity and hence BSO is unlikely to markedly enhance the activity of this ADEPT treatment. © 2000 Cancer Research Campaig

Seasonal dependence of peroxy radical concentrations at a northern hemisphere marine boundary layer site during summer and winter: evidence for photochemical activity in winter

International audiencePeroxy radicals (HO2+?RO2) were measured at the Weybourne Atmospheric Observatory (52° N, 1° E), Norfolk using a PEroxy Radical Chemical Amplifier (PERCA) during the winter and summer of 2002. The peroxy radical diurnal cycles showed a marked difference between the winter and summer campaigns with maximum concentrations of 12 pptv at midday in the summer and maximum concentrations as high as 30 pptv (10 min averages) in winter at night. The corresponding nighttime peroxy radical concentrations were not as high in summer (3 pptv). The peroxy radical concentration shows a distinct anti-correlation with increasing NOx during the daylight hours. At night, peroxy radicals increase with increasing NOx indicative of the role of NO3 chemistry. The average diurnal cycles for net ozone production, N(O3) show a large variability in ozone production, P(O3), and a large ozone loss, L(O3) in summer relative to winter. For a daylight average, net ozone production in summer than winter (1.51±0.5 ppbv h?1 and 1.11±0.47 ppbv h?1 respectively) but summer shows more variability of (meteorological) conditions than winter. The variability in NO concentration has a much larger effect on N(O3) than the peroxy radical concentrations. Photostationary state (PSS) calculations show an NO2 lifetime of 5 min in summer and 21 min in the winter, implying that steady-state NO-NO2 ratios are not always attained during the winter months. The results show an active peroxy radical chemistry at night and the ability of winter to make oxidant. The net effect of this with respect to production of ozone in winter is unclear owing to the breakdown in the photostationary state

Intercomparison of aircraft instruments on board the <i>C-130</i> and <i>Falcon 20</i> over southern Germany during EXPORT 2000

International audienceIn the summer 2000 Export aircraft campaign (European eXport of Precursors and Ozone by long-Range Transport), two comprehensively instrumented research aircraft measuring a variety of chemical species flew wing tip to wing tip for a period of one and a quarter hours. During this interval a comparison was undertaken of the measurements of nitrogen oxide (NO), odd nitrogen species (NOy), carbon monoxide (CO) and ozone (O3). The comparison was performed at two different flight levels, which provided a 10-fold variation in the concentrations of both NO (10 to 1000 parts per trillion by volume (pptv)) and NOy (200 to over 2500 pptv). Large peaks of NO and NOy observed from the Falcon 20, which were at first thought to be from the exhaust of the C-130, were also detected on the 4 channel NOx,y instrument aboard the C-130. These peaks were a good indication that both aircraft were in the same air mass and that the Falcon 20 was not in the exhaust plume of the C-130. Correlations and statistical analysis are presented between the instruments used on the two separate aircraft platforms. These were found to be in good agreement giving a high degree of correlation for the ambient air studied. Any deviations from the correlations are accounted for in the estimated inaccuracies of the instruments. These results help to establish that the instruments aboard the separate aircraft are reliably able to measure the corresponding chemical species in the range of conditions sampled and that data collected by both aircraft can be co-ordinated for purposes of interpretation