Two-color cavity ringdown spectroscopy: Optical detection of room-temperature 14^{14}CO2_2 samples at parts-per-quadrillion concentration level

Detection sensitivity is often one of the most important attributes to consider during selection of spectroscopic techniques. However, high sensitivity alone is insufficient for spectroscopic measurements and peak assignments in spectrally congested regions. Two-color cavity ringdown spectroscopy (2C-CRDS), based on intra-cavity pump-probe detection, simultaneously achieves high detection sensitivity, selectivity, and accuracy. Thanks to its built-in compensation for instrumental baseline fluctuations and one-photon background molecular signals, 2C-CRDS enables mid-IR detection of radiocarbon dioxide ($^{14}$CO$_2$) in $room$-$temperature$ CO$_2$ samples, with better than 10 parts-per-quadrillion (ppq) measurement $sensitivity$ and $accuracy$ (4 ppq on average from four separate trial measurements). This detection capability is prohibitively challenging for other existing spectroscopic techniques based on one-photon absorption, because of severe spectral overlap between the very weak $^{14}$CO$_2$ signals and the orders-of-magnitude stronger hot-band signals from other CO$_2$ isotopologues at room temperature. 2C-CRDS measurements of room-temperature $^{14}$CO$_2$ samples at the record sub-10-ppq concentration level could directly benefit a wide range of scientific fields that utilize $^{14}$C for dating and isotope tracing, especially during field deployment. The 2C-CRDS technique significantly enhances the sensitivity and general utility of high-resolution mid-IR detection for analytical trace measurements and fundamental chemical dynamics studies.Comment: 14 pages, 5 figures, 1 tabl

Room-temperature quantification of 14^{14}CO2_{2} below the natural abundance with two-color cavity ring-down spectroscopy

Radiocarbon's natural production, radiative decay, and isotopic rarity make it a unique tool to probe carbonaceous systems in the life and earth sciences. However, the difficulty of current radiocarbon ($^{14}$C) detection methods limits scientific adoption. Here, two-color cavity ring-down spectroscopy detects $^{14}$CO$_{2}$ in room-temperature samples with an accuracy of 8% of the natural abundance in 3 minutes. The intra-cavity pump-probe measurement uses two cavity-enhanced lasers to cancel out cavity ring-down rate fluctuations and strong one-photon absorption interference (>10,000 1/s) from hot-band transitions of CO$_{2}$ isotopologues. Selective, room-temperature detection of small $^{14}$CO$_{2}$ absorption signals (<1 1/s) reduces the technical and operational burdens for cavity-enhanced measurements of radiocarbon, which can benefit a wide range of applications like biomedical research and field-detection of combusted fossil fuels.Comment: 4 main figures, 2 supplementary figure

Prefrontal cortex activation and young driver behaviour: a fNIRS study

Road traffic accidents consistently show a significant over-representation for young, novice and particularly male drivers. This research examines the prefrontal cortex activation of young drivers and the changes in activation associated with manipulations of mental workload and inhibitory control. It also considers the explanation that a lack of prefrontal cortex maturation is a contributing factor to the higher accident risk in this young driver population. The prefrontal cortex is associated with a number of factors including mental workload and inhibitory control, both of which are also related to road traffic accidents. This experiment used functional near infrared spectroscopy to measure prefrontal cortex activity during five simulated driving tasks: one following task and four overtaking tasks at varying traffic densities which aimed to dissociate workload and inhibitory control. Age, experience and gender were controlled for throughout the experiment. The results showed that younger drivers had reduced prefrontal cortex activity compared to older drivers. When both mental workload and inhibitory control increased prefrontal cortex activity also increased, however when inhibitory control alone increased there were no changes in activity. Along with an increase in activity during overtaking manoeuvres, these results suggest that prefrontal cortex activation is more indicative of workload in the current task. There were no differences in the number of overtakes completed by younger and older drivers but males overtook significantly more than females. We conclude that prefrontal cortex activity is associated with the mental workload required for overtaking. We additionally suggest that the reduced activation in younger drivers may be related to a lack of prefrontal maturation which could contribute to the increased crash risk seen in this population

Public, private and personal: Qualitative research on policymakers' opinions on smokefree interventions to protect children in 'private' spaces

<p>Abstract</p> <p>Background</p> <p>Governments use law to constrain aspects of private activities for purposes of protecting health and social wellbeing. Policymakers have a range of perceptions and beliefs about what is public or private. An understanding of the possible drivers of policymaker decisions about where government can or should intervene for health is important, as one way to better guide appropriate policy formation. Our aim was to identify obstacles to, and opportunities for, government smokefree regulation of private and public spaces to protect children. In particular, to seek policymaker opinions on the regulation of smoking in homes, cars and public parks and playgrounds in a country with incomplete smokefree laws (New Zealand).</p> <p>Methods</p> <p>Case study, using structured interviews to ask policymakers (62 politicians and senior officials) about their opinions on new smokefree legislation for public and private places. Supplementary data was obtained from the Factiva media database, on the views of New Zealand local authority councillors about policies for smokefree outdoor public places.</p> <p>Results</p> <p>Overall, interviewees thought that government regulation of smoking in private places was impractical and unwise. However, there were some differences on what <it>was </it>defined as 'private', particularly for cars. Even in public parks, smoking was seen by some as a 'personal' decision, and unlikely to be amenable to regulation. Most participants believed that educative, supportive and community-based measures were better and more practical means of reducing smoking in private places, compared to regulation.</p> <p>Conclusions</p> <p>The constrained view of the role of regulation of smoking in public and private domains may be in keeping with current political discourse in New Zealand and similar Anglo-American countries. Policy and advocacy options to promote additional smokefree measures include providing a better voice for childrens' views, increasing information to policymakers about the harms to children from secondhand smoke and the example of adult smoking, and changing the culture for smoking around children.</p

Insomnia symptoms and repressive coping in a sample of older Black and White women

BACKGROUND: This study examined whether ethnic differences in insomnia symptoms are mediated by differences in repressive coping styles. METHODS: A total of 1274 women (average age = 59.36 ± 6.53 years) participated in the study; 28% were White and 72% were Black. Older women in Brooklyn, NY were recruited using a stratified, cluster-sampling technique. Trained staff conducted face-to-face interviews lasting 1.5 hours acquiring sociodemographic data, health characteristics, and risk factors. A sleep questionnaire was administered and individual repressive coping styles were assessed. Fisher's exact test and Spearman and Pearson analyses were used to analyze the data. RESULTS: The rate of insomnia symptoms was greater among White women [74% vs. 46%; χ(2 )= 87.67, p < 0.0001]. Black women scored higher on the repressive coping scale than did White women [Black = 37.52 ± 6.99, White = 29.78 ± 7.38, F(1,1272 )= 304.75, p < 0.0001]. We observed stronger correlations between repressive coping and insomnia symptoms for Black [r(s )= -0.43, p < 0.0001] than for White women [r(s )= -0.18, p < 0.0001]. Controlling for variation in repressive coping, the magnitude of the correlation between ethnicity and insomnia symptoms was substantially reduced. Multivariate adjustment for differences in sociodemographics, health risk factors, physical health, and health beliefs and attitudes had little effect on the relationships. CONCLUSION: Relationships between ethnicity and insomnia symptoms are jointly dependent on the degree of repressive coping, suggesting that Black women may be reporting fewer insomnia symptoms because of a greater ability to route negative emotions from consciousness. It may be that Blacks cope with sleep problems within a positive self-regulatory framework, which allows them to deal more effectively with sleep-interfering psychological processes to stressful life events and to curtail dysfunctional sleep-interpreting processes

Understanding the social context of fatal road traffic collisions among young people: A qualitative analysis of narrative text in coroners' records

Background: Deaths and injuries on the road remain a major cause of premature death among young people across the world. Routinely collected data usually focuses on the mechanism of road traffic collisions and basic demographic data of those involved. This study aimed to supplement these routine sources with a thematic analysis of narrative text contained in coroners' records, to explore the wider social context in which collisions occur. Methods. Thematic analysis of narrative text from Coroners' records, retrieved from thirty-four fatalities among young people (16-24 year olds) occurring as a result of thirty road traffic collisions in a rural county in the south of England over the period 2005-2010. Results: Six key themes emerged: social driving, driving experience, interest in motor vehicles, driving behaviour, perception of driving ability, and emotional distress. Social driving (defined as a group of related behaviours including: driving as a social event in itself (i.e. without a pre-specified destination); driving to or from a social event; driving with accompanying passengers; driving late at night; driving where alcohol or drugs were a feature of the journey) was identified as a common feature across cases. Conclusions: Analysis of the wider social context in which road traffic collisions occur in young people can provide important information for understanding why collisions happen and developing targeted interventions to prevent them. It can complement routinely collected data, which often focuses on events immediately preceding a collision. Qualitative analysis of narrative text in coroner's records may provide a way of providing this type of information. These findings provide additional support for the case for Graduated Driver Licensing programmes to reduce collisions involving young people, and also suggest that road safety interventions need to take a more community development approach, recognising the importance of social context and focusing on social networks of young people. © 2014 Pilkington et al.; licensee BioMed Central Ltd