530 research outputs found
Sunspot Group Development in High Resolution
The Solar and Heliospheric Obseratory/Michelson Doppler Imager--Debrecen Data
(SDD) sunspot catalogue provides an opportunity to study the details and
development of sunspot groups on a large statistical sample. The SDD data
allow, in particular, the differential study of the leading and following parts
with a temporal resolution of 1.5 hours. In this study, we analyse the
equilibrium distance of sunspot groups as well as the evolution of this
distance over the lifetime of the groups and the shifts in longitude associated
with these groups. We also study the asymmetry between the compactness of the
leading and following parts, as well as the time-profiles for the development
of the area of sunspot groups. A logarithmic relationship has been found
between the total area and the distance of leading-following parts of active
regions (ARs) at the time of their maximum area. In the developing phase the
leading part moves forward; this is more noticeable in larger ARs. The leading
part has a higher growth rate than the trailing part in most cases in the
developing phase. The growth rates of the sunspot groups depend linearly on
their maximum total umbral area. There is an asymmetry in compactness: the
number of spots tends to be smaller, while their mean area is larger in the
leading part at the maximum phase.Comment: 16 pages, 10 figure
Active-Region Tilt Angles: Magnetic Versus White-Light Determinations of Joy's Law
The axes of solar active regions are inclined relative to the east--west
direction, with the tilt angle tending to increase with latitude ("Joy's law").
Observational determinations of Joy's law have been based either on white-light
images of sunspot groups or on magnetograms, where the latter have the
advantage of measuring directly the physically relevant quantity (the
photospheric field), but the disadvantage of having been recorded routinely
only since the mid-1960s. White-light studies employing the historical Mount
Wilson (MW) database have yielded tilt angles that are smaller and that
increase less steeply with latitude than those obtained from magnetic data. We
confirm this effect by comparing sunspot-group tilt angles from the Debrecen
Photoheliographic Database with measurements made by Li and Ulrich using MW
magnetograms taken during cycles 21--23. Whether white-light or magnetic data
are employed, the median tilt angles significantly exceed the mean values, and
provide a better characterization of the observed distributions. The
discrepancy between the white-light and magnetic results is found to have two
main sources. First, a substantial fraction of the white-light "tilt angles"
refer to sunspots of the same polarity. Of greater physical significance is
that the magnetograph measurements include the contribution of plage areas,
which are invisible in white-light images but tend to have greater axial
inclinations than the adjacent sunspots. Given the large uncertainties inherent
in both the white-light and the magnetic measurements, it remains unclear
whether any systematic relationship exists between tilt angle and cycle
amplitude during cycles 16--23.Comment: 35 pages, 13 figures, Accepted in Ap
The International Division of Labor in Economists' Field: Academic Subordination in Exchange for Political Prerogatives in Argentina
Since the 1970s, economics has emerged as a global profession, with economists becoming main characters of the intellectual and political life in many countries. Inspired by Bourdieu, several analyses faced the challenge of “theorizing fields beyond the nation-state” (Buchholz 2016). Some scholars emphasized that internationalization entailed a growing asymmetry between dominant and dominated participants: the former acting as “exporters” and the latter as “importers” of ideas (Dezalay and Garth 2002). Others pointed out the process of “creative destruction” that accompanied the globalization of local fields (Fourcade 2006). Finally, still others noted the emergence of a new field of globalized experts and think tanks (Medvetz 2012). Through a socio-historical depiction of economists in Argentina, we problematize the subordinated role of peripheral economists. Rather than a dominant-dominated logic, we identify a new international division of labor. Based on more than 60 interviews with economists, archival research, and statistical analyses, this paper shows that while a dependent position in the global academic field reduced Argentinian economists’ theoretical autonomy, it gave them the scientific authority that in turn paved the road to access very well-paid work as consultants and high-level public servants
Incorporating prior knowledge improves detection of differences in bacterial growth rate
BACKGROUND: Robust statistical detection of differences in the bacterial growth rate can be challenging, particularly when dealing with small differences or noisy data. The Bayesian approach provides a consistent framework for inferring model parameters and comparing hypotheses. The method captures the full uncertainty of parameter values, whilst making effective use of prior knowledge about a given system to improve estimation. RESULTS: We demonstrated the application of Bayesian analysis to bacterial growth curve comparison. Following extensive testing of the method, the analysis was applied to the large dataset of bacterial responses which are freely available at the web-resource, ComBase. Detection was found to be improved by using prior knowledge from clusters of previously analysed experimental results at similar environmental conditions. A comparison was also made to a more traditional statistical testing method, the F-test, and Bayesian analysis was found to perform more conclusively and to be capable of attributing significance to more subtle differences in growth rate. CONCLUSIONS: We have demonstrated that by making use of existing experimental knowledge, it is possible to significantly improve detection of differences in bacterial growth rate
Excess electron solvation in ammonia clusters
We performed a combination of quantum chemical calculations and molecular dynamics simulations to assess the stability of various size ("N" "H" _"3" )_n^- ammonia cluster anions up to n = 32 monomers. In the n = 3 – 8 size range, cluster anions are optimized and the vertical detachment energy of the excess electron (VDE) from increasing size clusters are computed using various level methods including density functional theory (DFT), MP2 and CCSD(T) calculations. These clusters bind the electron in non-branched hydrogen bonding chains in dipole bound states. The VDE increases with size from a few meV up to ~200 meV. The electron binding energy is weaker than in water clusters but comparable to small methanol cluster VDEs. We located the first branched hydrogen bonding cluster that binds the excess electron at n = 7. For larger (n = 8 – 32) clusters we generated cold, neutral clusters by semiempirical and ab initio molecular dynamics (AIMD) simulations, and added an extra electron to selected neutral configurations. VDE calculations on the adiabatic and the relaxed anionic structures suggest that the n = 12 - 32 neutral clusters weakly bind the excess electron. Electron binding energies for these clusters (~ 100 meV) appear to be significantly weaker than extrapolated from experimental data. The observed excess electron states are diffuse and localized outside the molecular frame (surface states) with minor (~1%) penetration to the nitrogen frontier orbitals. Stable minima with excess electron states surrounded by solvent molecules (cavity states) were not found in this size regime
Long time blood-transfusion trend in a European general hospital
Reports about long-time transfusion trends in Austrian hospitals are rare. In our hospital, we implemented an algorithm of preoperative anemia management as part of a patient blood management (PBM) program in October 2011. Anemic individuals with elective surgery underwent an adequate preoperative anemia classification and treatment with erythropoietin and intravenous iron. The aim of this study was to assess red blood cell (RBC), platelet and plasma transfusions before and after implementation of an anemia management program in a general hospital in Austria. This retrospective study evaluated a 12-year trend (2006 – 2017) of RBC, platelet and plasma transfusions in an Austrian general hospital comprising a 6-year period before (2006 – 2011) and a 6-year period after (2012 – 2017) the implementation of an algorithm-guided anemia management. From overall 49,142 transfused RBC units between 2006 - 2017, 22,745 units were transfused in the post-implementation period compared to 26,397 units before PBM initiation (-13.8 %). The plasma unit use decreased also distinctly (787 vs. 1065 units, - 26.1 %) in the period after PBM implementation, whereas a slight decrease of platelet concentration use (807 vs. 843 units, - 4.3 %) was observed, only. This study demonstrates a 12-year pattern of blood use in an Austrian hospital with a distinct decreasing trend of transfused RBC and plasma units during this period. The implementation of PBM activities decreased the need of blood utilization at our institution. Further initiatives are needed to continue this trend in the next years
Solar Flare Intermittency and the Earth's Temperature Anomalies
We argue that earth's short-term temperature anomalies and the solar flare
intermittency are linked. The analysis is based upon the study of the scaling
of both the spreading and the entropy of the diffusion generated by the
fluctuations of the temperature time series. The joint use of these two methods
evidences the presence of a L\'{e}vy component in the temporal persistence of
the temperature data sets that corresponds to the one that would be induced by
the solar flare intermittency. The mean monthly temperature datasets cover the
period from 1856 to 2002.Comment: 4 pages, 5 figure
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