2,547 research outputs found
Theoretical X-Ray Absorption Debye-Waller Factors
An approach is presented for theoretical calculations of the Debye-Waller
factors in x-ray absorption spectra. These factors are represented in terms of
the cumulant expansion up to third order. They account respectively for the net
thermal expansion , the mean-square relative displacements
, and the asymmetry of the pair distribution function
. Similarly, we obtain Debye-Waller factors for x-ray and
neutron scattering in terms of the mean-square vibrational amplitudes .
Our method is based on density functional theory calculations of the dynamical
matrix, together with an efficient Lanczos algorithm for projected phonon
spectra within the quasi-harmonic approximation. Due to anharmonicity in the
interatomic forces, the results are highly sensitive to variations in the
equilibrium lattice constants, and hence to the choice of exchange-correlation
potential. In order to treat this sensitivity, we introduce two prescriptions:
one based on the local density approximation, and a second based on a modified
generalized gradient approximation. Illustrative results for the leading
cumulants are presented for several materials and compared with experiment and
with correlated Einstein and Debye models. We also obtain Born-von Karman
parameters and corrections due to perpendicular vibrations.Comment: 11 pages, 8 figure
Comparison of tumour-based (Petersen Index) and inflammation-based (Glasgow Prognostic Score) scoring systems in patients undergoing curative resection for colon cancer
After resection, it is important to identify colon cancer patients, who are at a high risk of recurrence and who may benefit from adjuvant treatment. The Petersen Index (PI), a prognostic model based on pathological criteria is validated in Dukes' B and C disease. Similarly, the modified Glasgow Prognostic Score (mGPS) based on biochemical criteria has also been validated. This study compares both the scores in patients undergoing curative resection of colon cancer. A total of 244 patients underwent elective resection between 1997 and 2005. The PI was constructed from pathological reports; the mGPS was measured pre-operatively. The median follow-up was 67 months (minimum 36 months) during which 109 patients died; 68 of them from cancer. On multivariate analysis of age, Dukes' stage, PI and mGPS, age (hazard ratio, HR, 1.74, P=0.001), Dukes' stage (HR, 3.63, P<0.001), PI (HR, 2.05, P=0.010) and mGPS (HR, 2.34, P<0.001) were associated independently with cancer-specific survival. Three-year cancer-specific survival rates for Dukes' B patients with the low-risk PI were 98, 92 and 82% for the mGPS of 0, 1 and 2, respectively (P<0.05). The high-risk PI population is small, in particular for Dukes' B disease (9%). The mGPS further stratifies those patients classified as low risk by the PI. Combining both the scoring systems could identify patients who have undergone curative surgery but are at high-risk of cancer-related death, therefore guiding management and trial stratification
Identification of plasma and urinary metabolites and catabolites derived from orange juice (poly)phenols: analysis by high-performance liquid chromatographyâhigh-resolution mass spectrometry
Orange juice is a rich source of (poly)phenols, in particular, the flavanones hesperetin-7-O-rutinoside and naringenin-7-O-rutinoside. Following the acute consumption of 500 mL of orange juice containing 398 ÎŒmol of (poly)phenols by 12 volunteers, 0â24 h plasma and urine samples were analyzed by targeted high-performance liquid chromatographyâhigh-resolution mass spectrometry in order to identify flavanone metabolites and phenolic acid and aromatic catabolites. A total of 19 flavanone metabolitesâcomprising di-O-glucuronide, O-glucuronide, O-glucuronyl-sulfate, and sulfate derivatives of hesperetin, naringenin, and eriodictyolâand 65 microbial-derived phenolic catabolites, such as phenylpropanoid, phenylpropionic, phenylacetic, benzoic, and hydroxycarboxylic acids and benzenetriol and benzoylglycine derivatives, including free phenolics and phase II sulfate, glucuronide, and methyl metabolites, were identified or partially identified in plasma and/or urine samples. The data obtained provide a detailed evaluation of the fate of orange juice (poly)phenols as they pass through the gastrointestinal tract and are absorbed into the circulatory system prior to renal excretion. Potential pathways for these conversions are proposed
Monkey see, monkey do? Exploring parent-athlete behaviours from youth athletes' perspective
Parents are an important social agent that can shape their child's behaviour in sport. However, the association between a youth athlete's perception of their parent's sideline sport behaviour and their own sporting behaviours is currently unclear. Therefore, the purpose of the present study was to explore the relationship between parent and youth athlete behaviours in sport settings. Australian youth athletes (nâ=â67) participating in team-based sports completed an online survey where they reported their parents positive and negative sideline behaviours and their own prosocial and antisocial sport behaviour during the past month. Linear regression results suggested that parent's positive behaviours were associated with youth prosocial behaviours, whereas parent's negative behaviours were associated with youth antisocial behaviours. Results provide preliminary quantitative evidence that youth athletes' perceptions of their parents' sideline behaviours predict their own on-field behaviours. As antisocial athlete behaviours were positively associated with parent negative behaviours, sport organisations should target, and ideally eliminate, negative parent behaviours. Conversely, to improve prosocial athlete behaviour, encouraging positive parent behaviours should be promoted
Perceived importance of components of asynchronous music in circuit training
This study examined regular exercisersâ perceptions of specific components of music
during circuit training. Twenty-four men (38.8 years, s = 11.8 years) and 31 women
(32.4 years, s = 9.6 years) completed two questionnaires immediately after a circuit
training class. Participants rated the importance of 13 components of music (rhythm,
melody, etc.) in relation to exercise enjoyment, and each completed the Affect Intensity
Measure (Larsen, 1984) to measure emotional reactivity. Independent t tests were used
to evaluate gender differences in perceptions of musical importance. Pearson
correlations were computed to evaluate the relationships between affect intensity, age
and importance of musical components. Consistent with previous research and
theoretical predictions, rhythm response components (rhythm, tempo, beat) were rated
as most important. Women rated the importance of melody significantly higher than did
men, while men gave more importance to music associated with sport. Affect intensity
was found to be positively and significantly related to the perceived importance of
melody, lyrical content, musical style, personal associations and emotional content.
Results suggest that exercise leaders need to be sensitive to personal factors when
choosing music to accompany exercise. Qualitative research that focuses on the
personal meaning of music is encouraged
Labour market experiences of young UK Bangladeshi men: Identity, inclusion and exclusion in inner-city London
Detailed qualitative data are used to explore the processes perpetuatinglabour market disadvantage among young UK-Bangladeshi men living in central London. Strong forces of inclusion within the Bangladeshi community are found to interact with forces of exclusion from âmainstreamâ
society to constrain aspirations and limit opportunities. Though diverse forms of young Bangladeshi masculinity are found, a common pattern is heavy dependency on intra-ethnic networks. Negative experiences of and isolation from âmainstreamâ society further reinforce reliance
on âour own peopleâ. However, acute ambivalence towards belonging to a dense Bangladeshi community exists, exemplified in the widespread denigration of the restaurant trade. Many respondents express the desire to âbreak outâ and access new experiences. The findings support current
policy emphasis on âconnecting people to workâ but highlight the more fundamental need to connect people across ethnic boundaries. The paper urges researchers to âunpackâ ethnicity to consider carefully what ethnic
identity implies in terms of access to resources and opportunities for different individuals in different contexts in order better to understand the diversity of labour market outcomes and the persistence of disadvantage
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High pressure x-ray absorption studies of phase transitions
High pressure generally changes all of the properties of substances, leading to phase transitions in many cases. This paper reviews how such phase changes reveal themselves in x-ray absorption spectra. Examples are given using the salts NaBr, RbCl, CuBr, and SnSe. (DLC
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