819 research outputs found
A combined NMR and DFT study of Narrow Gap Semiconductors: The case of PbTe
In this study we present an alternative approach to separating contributions
to the NMR shift originating from the Knight shift and chemical shielding by a
combination of experimental solid-state NMR results and ab initio calculations.
The chemical and Knight shifts are normally distinguished through detailed
studies of the resonance frequency as function of temperature and carrier
concentration, followed by extrapolation of the shift to zero carrier
concentration. This approach is time-consuming and requires studies of multiple
samples. Here, we analyzed Pb and Te NMR spin-lattice
relaxation rates and NMR shifts for bulk and nanoscale PbTe. The shifts are
compared with calculations of the Pb and Te chemical shift
resonances to determine the chemical shift at zero charge carrier
concentration. The results are in good agreement with literature values from
carrier concentration-dependent studies. The measurements are also compared to
literature reports of the Pb and Te Knight shifts of - and
-type PbTe semiconductors. The literature data have been converted to the
currently accepted shift scale. We also provide possible evidence for the
"self-cleaning effect" property of PbTe nanocrystals whereby defects are
removed from the core of the particles, while preserving the crystal structure.Comment: 34 pages, 9 figure
Back To Basics: Teaching The Statement Of Cash Flows
A conceptual foundation for the Statement of Cash Flows based on the ten elements of financial statements provides students with a deep understanding of core accounting concepts. Traditional methods of teaching the statement of cash flows tend to focus on statement preparation rules, masking the effect of business events on the change in cash. Accounting majors and non-majors alike both benefit from a clear understanding of the direct relationship between economic events and financial statement elements.  This teaching note provides a conceptual illustration of the Statement of Cash Flows based on the ten elements of financial statements. The teaching method used is based on the belief that “keeping it simple” results in deeper understanding. This paper develops an equation for the Statement of Cash Flows directly from the Balance Sheet focusing on ten elements of financial statements. The equation analysis is followed by a flowchart illustrating the process and a simple numeric example. Â
Continued Professional Competence and Portfolios
It is traditionally assumed that licensure of healthcare professionals means that they are minimally competent. Many nursing specialty organizations offer examinations and other processes for certification, suggesting that certification is associated with continued competency. Can standardized examination for certification and continuing education for recertification ensure continued competency? Continuing education and testing provide a limited picture of an individual\u27s knowledge and/or skill acquisition in a limited area at one point in time. However, portfolios promote critical thinking, self-assessment, and individual accountability. A portfolio is a portable mechanism for evaluating competencies that may otherwise be difficult to assess. This article summarizes some of the literature addressing portfolios, including aspects of portfolio development process, the value of portfolios versus continuing education for competency assessment, evidence associated with portfolio usage, and suggestions for organizing nursing portfolios
A Longitudinal Study of Cultural Tourism and Quality of Life of Indianapolis Residents
poster abstractCultural tourism development is considered a viable channel to attract tourists to a destination and to enhance residents’ overall quality of life (QOL). This research reports the findings of a five-year study, from 2004-2008, to monitor patterns and changes in perceptions of cultural tourism and residents’ quality of life measurement. The series of studies yield interesting conclusions that have practical implications for Indianapolis city and tourism leaders who continually evaluate the cultural tourism initiatives and ways to improve the residents’ quality of life
Three-Dimensional Simulations of Dynamics of Accretion Flows Irradiated by a Quasar
We study the axisymmetric and non-axisymmetric, time-dependent hydrodynamics
of gas that is under the influence of the gravity of a super massive black hole
(SMBH) and the radiation force produced by a radiatively efficient flow
accreting onto the SMBH. We have considered two cases: (1) the formation of an
outflow from the accretion of the ambient gas without rotation and (2) that
with weak rotation. The main goals of this study are: (1) to examine if there
is a significant difference between the models with identical initial and
boundary conditions but in different dimensionality (2-D and 3-D), and (2) to
understand the gas dynamics in AGN. Our 3-D simulations of a non-rotating gas
show small yet noticeable non-axisymmetric small-scale features inside the
outflow. The outflow as a whole and the inflow do not seem to suffer from any
large-scale instability. In the rotating case, the non-axisymmetric features
are very prominent, especially in the outflow which consists of many cold dense
clouds entrained in a smoother hot flow. The 3-D outflow is non-axisymmetric
due to the shear and thermal instabilities. In both 2-D and 3-D simulations,
gas rotation increases the outflow thermal energy flux, but reduces the outflow
mass and kinetic energy fluxes. Rotation also leads to time variability and
fragmentation of the outflow in the radial and latitudinal directions. The
collimation of the outflow is reduced in the models with gas rotation. The time
variability in the mass and energy fluxes is reduced in the 3-D case because of
the outflow fragmentation in the azimuthal direction. The virial mass estimated
from the kinematics of the dense cold clouds found in our 3-D simulations of
rotating gas underestimates the actual mass used in the simulations by about 40
%. (Abbreviated)Comment: 19 pages, 14 figures. Accepted by ApJ. Movies and a full resolution
version of the preprint can be downloaded at
"http://www.physics.unlv.edu/~rk/research/agn_3d_rot.html
Short term appetite control in response to a 6-week exercise programme in sedentary volunteers
Previous cross-sectional studies have shown that sedentary males, unlike their active counterparts, are unable to compensate for previous energy intake (EI). The present study therefore investigated the effects of a 6-week moderate exercise programme (4 times per week, 65-75 % maximal heart rate) on appetite regulation in healthy sedentary volunteers using a longitudinal design. EI at a buffet meal 60 min after high-energy (HEP; 607 kcal) and low-energy (LEP; 246 kcal) preloads, together with 24 h cumulative EI, were measured in twenty-five healthy volunteers (eleven men; mean age 30 (SD 12) years, mean BMI 22.7 (SD 2.3) kg/m2), at baseline and after the exercise intervention. Subjective hunger and fullness were assessed throughout using visual analogue scales. ANOVA showed a significant preload x exercise interaction on 24 h cumulative EI, supporting an improvement in appetite control over this time period with the exercise programme. There was a trend towards improvement in energy compensation over the same period (8.9 (SD 118.5) % v. 79.5 (SD 146..4) %; P = 0.056). No preload x exercise interaction was observed for buffet EI. Secondary analysis, however, showed that although buffet EI after the two preloads was not significantly different at baseline, buffet EI after the HEP was significantly lower than after the LEP following the exercise intervention. The improvement in short-term appetite control with exercise was not explained by changes in subjective hunger or satiety. This longitudinal study supports the original cross-sectional findings and suggests that exercise may have a significant impact on short-term appetite control by leading to a more sensitive eating behaviour in response to previous EI. Further studies are needed to clarify the mechanisms involved
Extending the M_(bh)-sigma diagram with dense nuclear star clusters
Abridged: Four new nuclear star cluster masses, M_nc, plus seven upper
limits, are provided for galaxies with previously determined black hole masses,
M_bh. Together with a sample of 64 galaxies with direct M_bh measurements, 13
of which additionally now have M_nc measurements rather than only upper limits,
plus an additional 29 dwarf galaxies with available M_nc measurements and
velocity dispersions sigma, an (M_bh + M_nc)-sigma diagram is constructed.
Given that major dry galaxy merger events preserve the M_bh/L ratio, and given
that L ~ sigma^5 for luminous galaxies, it is first noted that the observation
M_bh ~ sigma^5 is consistent with expectations. For the fainter elliptical
galaxies it is known that L ~ sigma^2, and assuming a constant M_nc/L ratio
(Ferrarese et al.), the expectation that M_nc ~ sigma^2 is in broad agreement
with our new observational result that M_nc ~ sigma^{1.57\pm0.24}. This
exponent is however in contrast to the value of ~4 which has been reported
previously and interpreted in terms of a regulating feedback mechanism from
stellar winds.Comment: 6 pages, 2 figures. Submitted 08/08/2011 to MNRAS, first referee
report received 19/01/2012, accepted 10/02/201
Effects of chewing on appetite, food intake and gut hormones: A systematic review and meta-analysis
Aim: To conduct a systematic review of the effects of chewing on appetite, food intake and gut hormones, and a meta-analysis of the effects of chewing on self-reported hunger. Objectives: To seek insights into the relationship between chewing, appetite, food intake and gut hormones, and to consider potentially useful recommendations to promote benefits of chewing for weight management. Materials and methods: Papers were obtained from two electronic databases (Medline and Cochrane), from searches of reference lists, and from raw data collected from the figures in the articles. A total of 15 papers were identified that detailed 17 trials. All 15 papers were included in the systematic review; however, a further five studies were excluded from the meta-analysis because appropriate information on hunger ratings was not available. The meta-analysis was conducted on a total of 10 papers that detailed 13 trials. Results: Five of 16 experiments found a significant effect of chewing on satiation or satiety using self-report measures (visual analogue scales, VASs). Ten of 16 experiments found that chewing reduced food intake. Three of five studies showed that increasing the number of chews per bite increased relevant gut hormones and two linked this to subjective satiety. The meta-analysis found evidence of both publication bias and between study heterogeneity (IA2=93.4%, tau2=6.52, p<0.001) which decreased, but remained, when covariates were considered. Analysis of the heterogeneity found a substantial effect of the fasting period where the duration of fasting influenced the decrease in hunger due to chewing. Prolonged mastication significantly reduces self-reported hunger levels (hunger: -2.31 VAS point, 95% CI [-4.67, -1.38], p<0.001). Conclusions: Evidence currently suggests that chewing may decrease self-reported hunger and food intake, possibly through alterations in gut hormone responses related to satiety. Although preliminary, the results identify a need for additional research in the area. Focused, uniform, experimental designs are required to clearly understand the relationships that exist between mastication, appetite, satiety, food intake and, ultimately, body weight
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