3,568 research outputs found
Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy
Time-resolved photoelectron spectroscopy was used to obtain new information about the dynamics of electronic relaxation in gas-phase indole and 5-hydroxyindole following UV excitation with femtosecond laser pulses centred at 249 nm and 273 nm. Our analysis of the data was supported by ab initio calculations at the coupled cluster and complete-active-space self-consistent-field levels. The optically bright 1La and 1Lb electronic states of 1\u3c0\u3c0* character and spectroscopically dark and dissociative 1\u3c0\u3c3* states were all found to play a role in the overall relaxation process. In both molecules we conclude that the initially excited 1La state decays non-adiabatically on a sub 100 fs timescale via two competing pathways, populating either the subsequently long-lived 1Lb state or the 1\u3c0\u3c3* state localised along the N-H coordinate, which exhibits a lifetime on the order of 1 ps. In the case of 5-hydroxyindole, we conclude that the 1\u3c0\u3c3* state localised along the O-H coordinate plays little or no role in the relaxation dynamics at the two excitation wavelengths studied.Peer reviewed: YesNRC publication: Ye
X-ray Phase-Resolved Spectroscopy of PSRs B0531+21, B1509-58, and B0540-69 with RXTE
The Rossi X-ray Timing Explorer ({\sl RXTE}) has made hundreds of
observations on three famous young pulsars (PSRs) B0531+21 (Crab), B1509-58,
and B0540-69. Using the archive {\sl RXTE} data, we have studied the
phase-resolved spectral properties of these pulsars in details. The variation
of the X-ray spectrum with phase of PSR B0531+21 is confirmed here much more
precisely and more details are revealed than the previous studies: the spectrum
softens from the beginning of the first pulse, turns to harden right at the
pulse peak and becomes the hardest at the bottom of the bridge, softens
gradually until the second peak, and then softens rapidly. Different from the
previous studies, we found that the spectrum of PSR B1509-58 is significantly
harder in the center of the pulse, which is also in contrast to that of PSR
B0531+21. The variation of the X-ray spectrum of PSR B0540-69 seems similar to
that of PSR B1509-58, but with a lower significance. Using the about 10 years
of data span, we also studied the real time evolution of the spectra of these
pulsars, and no significant evolution has been detected. We have discussed
about the constraints of these results on theoretical models of pulsar X-ray
emission.Comment: 42 pages, 24 figure
Prediction of melt depth in selected architectural materials during high power diode laser treatment
The development of an accurate analysis procedure for many laser applications, including the surface treatment of architectural materials, is extremely complicated due to the multitude of process parameters and materials characteristics involved. A one-dimensional analytical model based on Fourierâs law, with quasi-stationary situations in an isotropic and inhomogeneous workpiece with a parabolic meltpool geometry being assumed, was successfully developed. This model, with the inclusion of an empirically determined correction factor, predicted high power diode laser (HPDL) induced melt depths in clay quarry tiles, ceramic tiles and ordinary Portland cement (OPC) that were in close agreement with those obtained experimentally. It was observed, however, that as the incident laser line energy increased (>15 W mm-1 s-1/2), the calculated and the experimental melt depths began to diverge at an increasing rate. It is believed that this observed increasing discrepancy can be attributed to the fact the model developed neglects sideways conduction which, although it can be reasonably neglected at low energy densities, becomes significant at higher energy densities since one-dimensional heat transfer no longer holds true
Demographic, behavioural and anthropometric correlates of food liking: A crossâsectional analysis of young adults
The degree to which foods are liked or disliked is associated with dietary intake and health behaviours. However, most food liking research has focused on single foods and nutrients and few studies have examined associations with demographics and health behaviours. Thus, this study aimed to investigate the association between food liking and socioâdemographics, health behaviours, diet quality and body mass index (BMI) in a sample of young Australian adults. Data from 1728 undergraduate students (21.8 (standard deviation [SD] 6.0) years; 76% female) were used. Food liking scores and a diet quality index (Dietary Guideline Index, DGI) were estimated from a Food Liking Questionnaire and Food Frequency Questionnaire (FFQ), respectively. Multivariate linear regression analyses were used to assess the association between food liking and correlates. Young adults with higher liking for encouraged core foods were older, female, did their own food shopping, consumed less packaged foods and had better diet quality. Higher liking for discretionary foods and beverages was associated with less healthy behaviours, such as smoking, higher BMI and lower diet quality. These results suggest that food liking measures may offer an appropriate methodology for understanding influences on young adults’ food choices, adding to the body of literature investigating the potential for food liking scores to assess diet–disease relationships
Researching the Ends of Identity: Birth and Death on Social Media
This paper argues that expanding the scope of social media studies to examine birth and early life at one end, and death and memorialisation at the other, demonstrates that social media is never just about an individual, but also the way individuals are always already joined together as families, groups, communities and more. Mapping these ends of identity also reveals more of the nuances of everyday social media use and its impact
Polyphase midâlatitude glaciation on Mars:Chronology of the formation of superposed glacierâlike forms from craterâcount dating
Reconstructing Mars's glacial history informs understanding of its physical environment and past climate. The known distribution of viscous flow features (VFFs) containing water ice suggests that its midâlatitudes were glaciated during the Late Amazonian period (the last several hundred million years). The identification of a subgroup of VFFsâcalled superposed glacier like forms (SGLFs)âflowing onto other VFFs, indicates multiple glacial phases may have occurred during this time. To explore the history and spatial extent of these glaciations, we record the distribution of SGLFs globally and use impactâcrater counting to date the SGLFs and the VFFs onto which they flow. Our inventory expands the handful of SGLFs reported in earlier literature to include 320 located throughout the midâlatitudes. Our dating reveals these SGLFs to be much younger than their underlying VFFs, which implies a spatiallyâasynchronous glaciation. SGLFs have been forming since âŒ65 Ma, and their ages are clustered in two distinct groups around 2â20 and 45â65 Ma, whereas the ages of their underlying VFFs span the last âŒ300 Ma diffusely. We discuss these results in the light of wellâknown uncertainties with the craterâdating method and infer that while ice sheets decayed over the Late Amazonian period, alpine glaciers waxed and waned in at least two major cycles before their final demise approximately two million years ago
The participation paradigm in audience research
As today's media simultaneously converge and diverge, fusing and hybridizing across digital services and platforms, some researchers argue that audiences are dead-long live the user! But for others, it is the complex interweaving of continuities and changes that demands attention, especially now that audiencing has become a vital mode of engaging with all dimensions of daily life. This article asks how we should research audiences in a digital networked age. I argue that, while many avenues are being actively pursued, many researchers are concentrating on the notion of participation, asking, on the one hand, what modes of participation are afforded to people by the particular media and communication infrastructures which mediate social, cultural or political spheres of life? And, on the other hand, how do people engage with, accede to, negotiate or contest this as they explore and invent new ways of connecting with each other through and around media? The features of this emerging participation paradigm of audience research are examined in this article
A revision of the British Chronostratigraphy within the Last Glacial-Interglacial Cycle based on new evidence from Arclid, Cheshire UK
Of the 24 Greenland interstadials (GI) in the Last Glacial-interglacial cycle (LGIC) only five are conventionally recognised in Britain. This paper aims to improve understanding of the LGIC in Britain from a site at Arclid, Cheshire. Sediments were characterised and luminescence used to establish a chronology. This found that the Chelford Sand Formation spans 77-47 ka with sand deposited initially by aeolian but later by fluvial transportation. Coleoptera and Diptera from the basal peat lens provided a reconstruction for a heather-rich heathland environment grazed by large herbivores, with summer temperatures between 13-18° C, and winter temperatures between -14 and 1°C. Flies included the earliest records of the blood-sucking horsefly Haematopota pluvialis, and the soldierfly Chloromyia formosa. The overlying Stockport Sand Formation was deposited fluvioglacially between 47-41 ka with the upper Stockport Till formed by the advance of the last British icesheet after ~33 ka. Stenothermic beetle analysis from Arclid indicate similarities with results from other British mid LGIC sites, some of which are at or beyond the limit of radiocarbon dating and may be of a similar age to Arclid. Basal organic sediments found at Arclid along with other reassigned sites are proposed as a new Arclid Interstadial. A revised British LGIC chronostratigraphy has the Wretton, Chelford and Brimpton Interstadials and the previously suggested but not widely recognised Cassington Interstadial. The Arclid Interstadial occurred after these, but prior to the Upton Warren Interstadial complex. This closes the previous gap in interstadials between the Brimpton Interstadial and the Upton Warren Interstadial complex within the British chronostratigraphy
Stimulating the innovation potential of 'routine' workers through workplace learning
Governments worldwide seek to upgrade the âbasic skills' of employees deemed to have low literacy and numeracy, in order to enable their greater productivity and participation in workplace practices. A longitudinal investigation of such interventions in the United Kingdom has examined the effects on employees and on organizations of engaging in basic skills programmes offered in and through the workplace. âTrackingâ of employees in selected organizational contexts has highlighted ways in which interplay between formal and informal workplace learning can help to create the environments for employees in lower grade jobs to use and expand their skills. This workplace learning is a precondition, a stimulus and an essential ingredient for participation in employee-driven innovation, as workers engage with others to vary, and eventually to change, work practices. © 2010, SAGE Publications. All rights reserved
Does the Supreme Court Follow the Economic Returns? A Response to A Macrotheory of the Court
Today, there is a widespread idea that parents need to learn how to carry out their roles as parents. Practices of parental learning operate throughout society. This article deals with one particular practice of parental learning, namely nanny TV, and the way in which ideal parents are constructed through such programmes. The point of departure is SOS family, a series broadcast on Swedish television in 2008. Proceeding from the theorising of governmentality developed in the wake of the work of Michel Foucault, we analyse the parental ideals conveyed in the series, as an example of the way parents are constituted as subjects in the âadvanced liberal societyâ of today. The ideal parent is a subject who, guided by the coach, is constantly endeavouring to achieve a makeover. The objective of this endeavour, however, is self-control, whereby the parents will in the end become their own coaches.
- âŠ