3,508 research outputs found
Application of Pressure-Sensitive Paint to Low-Speed Flow around a U-Bend of Strong Curvature
A note on the sign (unit root) ambiguities of Gauss sums in index 2 and 4 cases
Recently, the explicit evaluation of Gauss sums in the index 2 and 4 cases
have been given in several papers (see [2,3,7,8]). In the course of evaluation,
the sigh (or unit root) ambiguities are unavoidably occurred. This paper
presents another method, different from [7] and [8], to determine the sigh
(unit root) ambiguities of Gauss sums in the index 2 case, as well as the ones
with odd order in the non-cyclic index 4 case. And we note that the method in
this paper are more succinct and effective than [8] and [7]
Properties of dense partially random graphs
We study the properties of random graphs where for each vertex a {\it
neighbourhood} has been previously defined. The probability of an edge joining
two vertices depends on whether the vertices are neighbours or not, as happens
in Small World Graphs (SWGs). But we consider the case where the average degree
of each node is of order of the size of the graph (unlike SWGs, which are
sparse). This allows us to calculate the mean distance and clustering, that are
qualitatively similar (although not in such a dramatic scale range) to the case
of SWGs. We also obtain analytically the distribution of eigenvalues of the
corresponding adjacency matrices. This distribution is discrete for large
eigenvalues and continuous for small eigenvalues. The continuous part of the
distribution follows a semicircle law, whose width is proportional to the
"disorder" of the graph, whereas the discrete part is simply a rescaling of the
spectrum of the substrate. We apply our results to the calculation of the
mixing rate and the synchronizability threshold.Comment: 14 pages. To be published in Physical Review
Quantifying the prediction accuracy of a 1-D SVAT model at a range of ecosystems in the USA and Australia: evidence towards its use as a tool to study Earth's system interactions
This paper describes the validation of the SimSphere SVAT (Soil–Vegetation–Atmosphere Transfer) model conducted at
a range of US and
Australian ecosystem types. Specific focus was given to examining the models' ability
in predicting shortwave incoming solar radiation (Rg), net radiation
(Rnet), latent heat (LE), sensible heat (H), air temperature at 1.3 m
(Tair 1.3 m) and air temperature at 50 m (Tair 50 m). Model
predictions were compared against corresponding in situ measurements acquired for a
total of 72 selected days of the year 2011 obtained from eight sites belonging
to the AmeriFlux (USA) and OzFlux (Australia) monitoring networks. Selected
sites were representative of a variety of environmental, biome and climatic
conditions, to allow for the inclusion of contrasting conditions in the
model evaluation.
Overall, results showed a good agreement between the model predictions and
the in situ measurements, particularly so for the Rg, Rnet, Tair
1.3 m and Tair 50 m parameters. The simulated Rg parameter exhibited
a root mean square deviation (RMSD) within 25 % of the observed fluxes for
58 of the 72 selected days, whereas an RMSD within
~ 24 % of the observed fluxes was reported for the Rnet
parameter for all days of study (RMSD = 58.69 W m−2). A systematic
underestimation of Rg and Rnet (mean bias error (MBE) = −19.48
and −16.46 W m−2) was also found. Simulations for the
Tair 1.3 m and Tair 50 m showed good agreement with the
in situ observations, exhibiting RMSDs of 3.23 and
3.77 °C (within ~ 15 and ~ 18 %
of the observed) for all days of analysis, respectively. Comparable, yet
slightly less satisfactory simulation accuracies were exhibited for the H
and LE parameters (RMSDs = 38.47 and 55.06 W m−2, ~ 34 and ~ 28 % of the
observed). Highest simulation accuracies were obtained for the open woodland
savannah and mulga woodland sites for most of the compared parameters.
The Nash–Sutcliffe efficiency index for all parameters ranges from 0.720 to
0.998, suggesting a very good model representation of the observations.
To our knowledge, this study presents the most detailed evaluation of
SimSphere done so far, and the first validation of it conducted
in Australian ecosystem types. Findings are important and timely, given the
expanding use of the model both as an educational and research tool today.
This includes ongoing research by different space agencies examining its
synergistic use with Earth observation data towards the development of
global operational products
Quantum Theory and Galois Fields
We discuss the motivation and main results of a quantum theory over a Galois
field (GFQT). The goal of the paper is to describe main ideas of GFQT in a
simplest possible way and to give clear and simple arguments that GFQT is a
more natural quantum theory than the standard one. The paper has been prepared
as a presentation to the ICSSUR' 2005 conference (Besancon, France, May 2-6,
2005).Comment: Latex, 24 pages, 1 figur
Associations between e-cigarette access and smoking and drinking behaviours in teenagers
Background: Public health concerns regarding e-cigarettes and debate on appropriate regulatory responses are
focusing on the need to prevent child access to these devices. However, little is currently known about the
characteristics of those young people that are accessing e-cigarettes.
Methods: Using a cross-sectional survey of 14-17 year old school students in North West England (n = 16,193) we
examined associations between e-cigarette access and demographics, conventional smoking behaviours, alcohol
consumption, and methods of accessing cigarettes and alcohol. Access to e-cigarettes was identified through a
question asking students if they had ever tried or purchased e-cigarettes.
Results: One in five participants reported having accessed e-cigarettes (19.2%). Prevalence was highest among\ud
smokers (rising to 75.8% in those smoking >5 per day), although 15.8% of teenagers that had accessed e-cigarettes
had never smoked conventional cigarettes (v.13.6% being ex-smokers). E-cigarette access was independently
associated with male gender, having parents/guardians that smoke and students’ alcohol use. Compared with
non-drinkers, teenagers that drank alcohol at least weekly and binge drank were more likely to have accessed
e-cigarettes (adjusted odds ratio [AOR] 1.89, P < 0.001), with this association particularly strong among never-smokers
(AOR 4.59, P < 0.001). Among drinkers, e-cigarette access was related to: drinking to get drunk, alcohol-related violence,
consumption of spirits; self-purchase of alcohol from shops or supermarkets; and accessing alcohol by recruiting adult
proxy purchasers outside shops.
Conclusions: There is an urgent need for controls on the promotion and sale of e-cigarettes to children. Findings
suggest that e-cigarettes are being accessed by teenagers more for experimentation than smoking cessation. Those
most likely to access e-cigarettes may already be familiar with illicit methods of accessing age-restricted substances
Abundances in intermediate-mass AGB stars undergoing third dredge-up and hot-bottom burning
High dispersion near-infrared spectra have been taken of seven
highly-evolved, variable, intermediate-mass (4-6 Msun) AGB stars in the LMC and
SMC in order to look for C, N and O variations that are expected to arise from
third dredge-up and hot-bottom burning. The pulsation of the objects has been
modelled, yielding stellar masses, and spectral synthesis calculations have
been performed in order to derive abundances from the observed spectra. For two
stars, abundances of C, N, O, Na, Al, Ti, Sc and Fe were derived and compared
with the abundances predicted by detailed AGB models. Both stars show very
large N enhancements and C deficiencies. These results provide the first
observational confirmation of the long-predicted production of primary nitrogen
by the combination of third dredge-up and hot-bottom burning in
intermediate-mass AGB stars. It was not possible to derive abundances for the
remaining five stars: three were too cool to model, while another two had
strong shocks in their atmospheres which caused strong emission to fill the
line cores and made abundance determination impossible. The latter occurrence
allows us to predict the pulsation phase interval during which observations
should be made if successful abundance analysis is to be possible.Comment: Accepted for publication in MNRA
Regulation and Regulatory Role of WNT Signaling in Potentiating FSH Action during Bovine Dominant Follicle Selection
Follicular development occurs in wave like patterns in monotocous species such as cattle and humans and is regulated by a complex interaction of gonadotropins with local intrafollicular regulatory molecules. To further elucidate potential mechanisms controlling dominant follicle selection, granulosa cell RNA harvested from F1 (largest) and F2 (second largest) follicles isolated at predeviation (PD) and onset of diameter deviation (OD) stages of the first follicular wave was subjected to preliminary RNA transcriptome analysis. Expression of numerous WNT system components was observed. Hence experiments were performed to test the hypothesis that WNT signaling modulates FSH action on granulosa cells during follicular waves. Abundance of mRNA for WNT pathway members was evaluated in granulosa cells harvested from follicles at emergence (EM), PD, OD and early dominance (ED) stages of the first follicular wave. In F1 follicles, abundance of CTNNB1 and DVL1 mRNAs was higher and AXIN2 mRNA was lower at ED versus EM stages and DVL1 and FZD6 mRNAs were higher and AXIN2mRNA was lower in F1 versus F2 follicle at the ED stage. Bovine granulosa cells were treated in vitro with increasing doses of the WNT inhibitor IWR-1+/− maximal stimulatory dose of FSH. IWR-1 treatment blocked the FSH-induced increase in granulosa cell numbers and reduced the FSH-induced increase in estradiol. Granulosa cells were also cultured in the presence or absence of FSH +/− IWR-1 and hormonal regulation of mRNA for WNT pathway members and known FSH targets determined. FSH treatment increased CYP19A1, CCND2, CTNNB1, AXIN2and FZD6 mRNAs and the stimulatory effect on CYP19A1 mRNA was reduced by IWR-1. In contrast, FSH reduced CARTPT mRNA and IWR-1 partially reversed the inhibitory effect of FSH. Results support temporal and hormonal regulation and a potential role for WNT signaling in potentiating FSH action during dominant follicle selection
Inhomogeneities in molecular layers of Mira atmospheres
We obtained K-band spectro-interferometric observations of the Miras R Cnc, X
Hya, W Vel, and RW Vel with a spectral resolution of 1500 using the VLTI/AMBER
instrument. We obtained concurrent JHKL photometry using the the Mk II
instrument at the SAAO. Our sources have wavelength-dependent visibility values
that are consistent with earlier low-resolution AMBER observations of S Ori and
with the predictions of dynamic model atmosphere series based on self-excited
pulsation models. The wavelength-dependent UD diameters show a minimum near the
near-continuum bandpass at 2.25 um. They increase by up to 30% toward the H2O
band at 2.0 um and by up to 70% at the CO bandheads. The dynamic model
atmosphere series show a consistent wavelength-dependence, and their parameters
such as the visual phase, effective temperature, and distances are consistent
with independent estimates. The closure phases have significantly
wavelength-dependent non-zero values indicating deviations from point symmetry.
For example, the R Cnc closure phase is 110 degr in the 2.0 um H2O band,
corresponding for instance to an additional unresolved spot contributing 3% of
the total flux at a separation of ~4 mas. Our observations are consistent with
the predictions of the latest dynamic model atmosphere series based on
self-excited pulsation models. The wavelength-dependent radius variations are
interpreted as the effect of molecular layers. The wavelength-dependent closure
phase values are indicative of deviations from point symmetry at all
wavelengths, thus a complex non-spherical stratification of the extended
atmosphere. In particular, the significant deviation from point symmetry in the
H2O band is interpreted as a signature on large scales of inhomogeneities or
clumps in the water vapor layer. The observed inhomogeneities might be caused
by pulsation- and shock-induced chaotic motion in the extended atmosphere.Comment: 5 pages, 2 figures, accepted for publication as a Letter in Astronomy
and Astrophysic
Principles And Practices Fostering Inclusive Excellence: Lessons From The Howard Hughes Medical Institute’s Capstone Institutions
Best-practices pedagogy in science, technology, engineering, and mathematics (STEM) aims for inclusive excellence that fosters student persistence. This paper describes principles of inclusivity across 11 primarily undergraduate institutions designated as Capstone Awardees in Howard Hughes Medical Institute’s (HHMI) 2012 competition. The Capstones represent a range of institutional missions, student profiles, and geographical locations. Each successfully directed activities toward persistence of STEM students, especially those from traditionally underrepresented groups, through a set of common elements: mentoring programs to build community; research experiences to strengthen scientific skill/identity; attention to quantitative skills; and outreach/bridge programs to broaden the student pool. This paper grounds these program elements in learning theory, emphasizing their essential principles with examples of how they were implemented within institutional contexts. We also describe common assessment approaches that in many cases informed programming and created traction for stakeholder buy-in. The lessons learned from our shared experiences in pursuit of inclusive excellence, including the resources housed on our companion website, can inform others’ efforts to increase access to and persistence in STEM in higher education
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