427 research outputs found
Influence of a magnetic field on the viscosity of a dilute gas consisting of linear molecules.
The viscomagnetic effect for two linear molecules, N2 and CO2, has been calculated in the dilute-gas limit directly from the most accurate ab initio intermolecular potential energy surfaces presently available. The calculations were performed by means of the classical trajectory method in the temperature range from 70 K to 3000 K for N2 and 100 K to 2000 K for CO2, and agreement with the available experimental data is exceptionally good. Above room temperature, where no experimental data are available, the calculations provide the first quantitative information on the magnitude and the behavior of the viscomagnetic effect for these gases. In the presence of a magnetic field, the viscosities of nitrogen and carbon dioxide decrease by at most 0.3% and 0.7%, respectively. The results demonstrate that the viscomagnetic effect is dominated by the contribution of the jj¯ polarization at all temperatures, which shows that the alignment of the rotational axes of the molecules in the presence of a magnetic field is primarily responsible for the viscomagnetic effect
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Technologies of birth and models of midwifery care
This article is based on a study of a reform in the organisation of maternity services in the United Kingdom, which aimed towards developing a more woman-centred model of care. After decades of fragmentation and depersonalisation of care, associated with the shift of birth to a hospital setting, pressure by midwives and mothers prompted government review and a relatively radical turnaround in policy. However, the emergent model of care has been profoundly influenced by concepts and technologies of monitoring. The use of such technologies as ultrasound scans, electronic foetal monitoring and oxytocic augmentation of labour, generally supported by epidural anaesthesia for pain relief, have accompanied the development of a particular ecological model of birth – often called active management –, which is oriented towards the idea of an obstetric norm. Drawing on analysis of women’s narrative accounts of labour and birth, this article discusses the impact on women’s embodiment in birth, and the sources of information they use about the status of their own bodies, their labour and that of the child. It also illustrates how the impact on women’s experiences of birth may be mediated by a relational model of support, through the provision of caseload midwifery care
Low temperature structural phase transition and incommensurate lattice modulation in the spin gap compound BaCuSi2O6
Results of high resolution x-ray diffraction experiments are presented for
single crystals of the spin gap compound BaCuSiO in the temperature
range from 16 to 300 K. The data show clear evidence of a transition from the
room temperature tetragonal phase into an incommensurately modulated
orthorhombic structure below 100 K. This lattice modulation is
characterized by a resolution limited wave vector {\bf
q}=(0,0.13,0) and its 2 and 3 harmonics. The phase
transition is first order and exhibits considerable hysteresis. This
observation implies that the spin Hamiltonian representing the system is more
complex than originally thought.Comment: 4 pages, 4 figure
Bisecting the mental number line in near and far space
Much evidence suggests that common posterior parietal mechanisms underlie the orientation of attention in physical space and along the mental number line. For example, the small leftward bias (pseudoneglect) found in paper-and-pencil line bisection is also found when participants "bisect" number pairs, estimating (without calculating) the number midway between two others. For bisection of physical lines, pseudoneglect has been found to shift rightward as lines are moved from near space (immediately surrounding the body) to far space. We investigated whether the presentation of stimuli in near or far space also modulated spatial attention for the mental number line. Participants bisected physical lines or number pairs presented at four distances (60, 120, 180, 240 cm). Clear rightward shifts in bias were observed for both tasks. Furthermore, the rate at which this shift occurred in the two tasks, as measured by least squares regression slopes, was significantly correlated across participants, suggesting that the transition from near to far distances induced a common modulation of lateral attention in physical and numerical space. These results demonstrate a tight coupling between number and physical space, and show that even such prototypically abstract concepts as number are modulated by our on-line interactions with the world
Thiamin nutrition and catalysis-induced instability of thiamin diphosphate
Thiamin (vitamin B1) is required in animal diets because it is the precursor of the enzyme cofactor, thiamin diphosphate. Unlike other B vitamins, the dietary thiamin requirement is proportional to non-fat energy intake but there is no obvious biochemical reason for this relationship. In the present communication we show for two enzymes that the cofactor undergoes a slow destruction during catalysis, which may explain the interdependence of thiamin and energy intakes
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Prevalence of spontaneous, induced labour or planned caesarean section and factors associated with caesarean scetion and factors associated with caesarian section in low-risk women in southern Brazil
Objective
This study aimed to examine the prevalence of spontaneous labour, induced labour and planned caesarean section in low-risk women; to identify the contribution of each group to the overall caesarean section rate; and to estimate factors associated with caesarean section in low-risk women according to spontaneous labour, induced labour and planned caesarean section.
Design
Cross-sectional hospital-based study of postpartum women and newborns, using data from the survey Birth in Brazil, Southern region. In the sample of 2,668 low-risk women, a descriptive analysis was undertaken and a Multinomial Logistic Regression model was applied to verify associations among caesarean section and spontaneous labour, induced labour and planned caesarean section in comparison with vaginal birth.
Measurements and Findings
The results showed the prevalence of spontaneous labour (48.0%), induced labour (14.0%) and planned caesarean sections (38.0%); these frequencies contributed to an overall caesarean section rate of 50.5%. Obstetric characteristics like previous vaginal birth or previous caesarean section were differentially associated with caesarean section, independently of the labour. Caesarean section without labour was significantly associated with age ≥ 35 years (ORadj 5.45 95%CI 3.16-9.39), economic class A and B (ORadj 3.10 95%CI 1.92-4.99), pregnancy between 37 and 38 weeks (ORadj 1.65 95%CI 1.22-2.24), same obstetrician in prenatal and childbirth (ORadj 13.83 95%CI 8.85-21.61) and private payment source at birth (ORadj 11.50 95%CI 6.64-19.93).
Key conclusion
For low-risk women in Southern Brazil, the results identify high planned caesarean section rates, not associated with socioeconomic, obstetric, institutional or prenatal factors that justify these rates
Accounting students' IT applicaton skills over a 10-year period
This paper reports on the changing nature of a range of information technology (IT) application skills that students declare on entering an accounting degree over the period from 1996 to 2006. Accounting educators need to be aware of the IT skills students bring with them to university because of the implications this has for learning and teaching within the discipline and the importance of both general and specific IT skills within the practice and craft of accounting. Additionally, IT skills constitute a significant element within the portfolio of employability skills that are increasingly demanded by employers and emphasized within the overall Higher Education (HE) agenda. The analysis of students' reported IT application skills on entry to university, across a range of the most relevant areas of IT use in accounting, suggest that their skills have continued to improve over time. However, there are significant differential patterns of change through the years and within cohorts. The paper addresses the generalizability of these findings and discusses the implications of these factors for accounting educators, including the importance of recognising the differences that are potentially masked by the general increase in skills; the need for further research into the changing nature, and implications, of the gender gap in entrants' IT application skills; and the low levels of entrants' spreadsheet and database skills that are a cause for concern
Radiation therapy for vaginal and perirectal lesions in recurrent ovarian cancer
The role for localized radiation to treat ovarian cancer (OC) patients with locally recurrent vaginal/perirectal lesions remains unclear, though we hypothesize these patients may be salvaged locally and gain long-term survival benefit. We describe our institutional outcomes using intensity modulated radiation therapy (IMRT) +/- high-dose rate (HDR) brachytherapy to treat this population. Our primary objectives were to evaluate complete response rates of targeted lesions after radiation and calculate our 5-year in-field control (IFC) rate. Secondary objectives were to assess radiation-related toxicities, chemotherapy free-interval (CFI), as well as post-radiation progression-free (PFS) and overall survival (OS). PFS and OS were defined from radiation start to either progression or death/last follow-up, respectively. This was a heavily pre-treated cohort of 17 recurrent OC patients with a median follow-up of 28.4 months (range 4.5-166.4) after radiation completion. 52.9% had high-grade serous histology and 4 (23.5%) had isolated vaginal/perirectal disease. Four (23.5%) patients had in-field failures at 3.7, 11.2, 24.5, and 27.5 months after start of radiation, all treated with definitive dosing of radiation therapy. Patients who were platinum-sensitive prior to radiation had similar median PFS (6.5 vs. 13.4 months, log-rank p = 0.75), but longer OS (71.1 vs 18.8 months, log-rank p = 0.05) than their platinum-resistant counterparts. Excluding patients with low-grade histology or who were treated with palliative radiation, median CFI was 14.2 months (range 4.7 - 33.0). Radiation was well tolerated with 2 (12.0%) experiencing grade 3/4 gastrointestinal/genitourinary toxicities. In conclusion, radiation to treat locally recurrent vaginal/perirectal lesions in heavily pre-treated OC patients is safe and may effectively provide IFC
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