710 research outputs found
Automatic recognition and characterisation of supergranular cells from photospheric velocity fields
No full textWe have developed an exceptionally noise resistant method for accurate and automatic identification of supergranular cell boundaries from velocity measurements. Due to its high noise tolerance the algorithm can produce reliable cell patterns with only very small amounts of smoothing of the source data in comparison to conventional methods. In this paper we describe the method and test it with simulated data. We then apply it to the analysis of velocity fields derived from high-resolution continuum data from MDI (Michelson Doppler Imager) on SOHO. From this, we can identify certain basic properties of supergranulation cells, such as their characteristic sizes, the flow speeds within cells and their dependence on cell areas at high resolution. The effect of the noise and smoothing on the derived cell boundaries is investigated and quantified using simulated data. We show in detail the evolution of supergranular cells over their lifetime, including observations of emerging, splitting, and coalescing cells. A key result of our analysis of cell internal velocities is that there is a simple linear relation between cell size and cell internal velocity, rather than the power law usually suggested
H.E. Rainier letter to the Equal Suffrage League, September 9, 1914
No full textH.E. Rainier wrote this letter on September 9, 1914, addressed to the Equal Suffrage League, to inform the League of a debate Rainier would be participating in. Rainier requested facts and statistics that would help support women's suffrage in the debate on the issue of equal suffrage. Rainier requested statistics especially on the rates of divorce in states that had already achieved suffrage for women.
The Franklin County Woman Suffrage Association was formed in 1912, after the Ohio Constitutional Convention elected to bring to a vote the question of removing the words "white male" from the state constitution with regard to voting rights. Headquartered in the Chamber of Commerce building in Columbus, Ohio, the organization put out regular publications, organized public speeches and meetings, distributed literature and held parades in support of the suffrage movement. Women's suffrage in Ohio was defeated in a special election in 1912 and again in 1914 and 1916 before a resolution narrowly passed in 1917 allowing municipal voting by women in Columbus. In 1920, the 19th Amendment passed, extending the vote to women and prohibiting state and federal government from denying suffrage on the basis of sex
Small scale energy release driven by supergranular flows on the quiet Sun
No full textIn this article we present data and modelling for the quiet Sun that strongly suggest a ubiquitous small-scale atmospheric heating mechanism that is driven solely by converging supergranular flows.
A possible energy source for such events is the power transfer to the plasma via the work done on the magnetic field by photospheric convective flows, which exert drag of the footpoints of magnetic structures. In this paper we present evidence of small scale energy release events driven directly by the hydrodynamic forces that act on the magnetic elements in the photosphere, as a result of supergranular scale flows. We show strong spatial and temporal correlation between quiet Sun soft X-ray emission (from <i>Yohkoh</i> and <i>SOHO</i> MDI-derived flux removal events driven by deduced photospheric flows.
We also present a simple model of heating generated by flux submergence, based on particle acceleration by converging magnetic mirrors.
In the near future, high resolution soft X-ray images from XRT on the <i>Hinode</i> satellite will allow definitive, quantitative verification of our results
Behrensmeyer, A.K., Damuth, J.D., Di Michele, W.A., Potts, R., Sues, H.E. & Wing, S.L. — Terrestrial Ecosystems through Time. Evolutionary Paleoecology of Terrestrial Plants and Animals. The University of Chicago Press, Chicago and London, 1992
No full textBourlière François. Behrensmeyer, A.K., Damuth, J.D., Di Michele, W.A., Potts, R., Sues, H.E. & Wing, S.L. — Terrestrial Ecosystems through Time. Evolutionary Paleoecology of Terrestrial Plants and Animals. The University of Chicago Press, Chicago and London, 1992. In: Revue d'Écologie (La Terre et La Vie), tome 48, n°1, 1993. pp. 88-89
<Advanced Energy Generation Division> Advanced Energy Research Section
No full text3-1. Research Activities in 2022The author spent three months (Sep. 1, 2022-Nov. 30, 2022) as a guest associated professor at the Uji campus of Kyoto University, hosted by the Prof. H. Ohgaki's group. Here the author reports about an investigation on study of solvation structure and dynamics of room-temperature ionic liquids using MIR free-electron laser.The author spent three months (Jan 01 2023 -Mar. 31, 2023) as a guest professor at the Uji campus of Kyoto University, hosted by the Heliotron J group. Here the author reports about successes in turbulence modelling for Heliotron J.Advanced Energy Research Section/ Sakhorn Rimjaem [43]Advanced Energy Research Section/ Josefine H.E. Proll [45
Post-hoc derivation of SOHO Michelson doppler imager flat fields
No full text<p><b>Context:</b> The SOHO satellite now offers a unique perspective on the Sun as it is the only space-based instrument that can provide large, high-resolution data sets over an entire 11-year solar cycle. This unique property enables detailed studies of long-term variations in the Sun. One significant problem when looking for such changes is determining what component of any variation is due to deterioration of the instrument and what is due to the Sun itself. One of the key parameters that changes over time is the apparent sensitivity of individual pixels in the CCD array. This can change considerably as a result of optics damage, radiation damage, and aging of the sensor itself. In addition to reducing the sensitivity of the telescope over time, this damage significantly changes the uniformity of the flat field of the instrument, a property that is very hard to recalibrate in space. For procedures such as feature tracking and intensity analysis, this can cause significant errors.</p>
<p><b>Aims:</b> We present a method for deriving high-precision flat fields for high-resolution MDI continuum data, using analysis of existing continuum and magnetogram data sets.</p>
<p><b>Methods:</b> A flat field is constructed using a large set (1000-4000 frames) of cospatial magnetogram and continuum data. The magnetogram data is used to identify and mask out magnetically active regions on the continuum data, allowing systematic biases to be avoided. This flat field can then be used to correct individual continuum images from a similar time.</p>
<p><b>Results:</b> This method allows us to reduce the residual flat field error by around a factor 6-30, depending on the area considered, enough to significantly change the results from correlation-tracking analysis. One significant advantage of this method is that it can be done retrospectively using archived data, without requiring any special satellite operations.</p>
Author Correction: the Influence of Nano Filter Elements on Pressure Drop and Pollutant Elimination Efficiency in Town Border Stations
No full textThe original version of this Article contained an error in the order of the author names, which was incorrectly given as Hamed Ebadiyan, Saeed Zeinali Heris, Seyed Borhan Mousavi, Shamin Hosseini Nami ; Mousa Mohammadpourfard. Consequently, in the Author Contributions section, “H.E. Investigation. S.Z.H. Supervision, Conceptualization, Methodology, Validation. S.B.M. Formal analysis, Writing original draft. S.H.N. Formal analysis, Writing original draft. M.M. Validation.” now reads: “S.Z.H. Supervision, Conceptualization, Methodology, Validation. H.E. Investigation. S.B.M. Formal analysis, Writing original draft. S.H.N. Formal analysis, Writing original draft. M.M. Validation.” The original Article has been corrected. © 2023, The Author(s)
The evolution of electron overdensities in magnetic fields
No full textWhen a neutral gas impinges on a stationary magnetized plasma an enhancement in the ionization rate occurs when the neutrals exceed a threshold velocity. This is commonly known as the critical ionization velocity effect. This process has two distinct timescales: an ion–neutral collision time and electron acceleration time. We investigate the energization of an ensemble of electrons by their self-electric field in an applied magnetic field. The evolution of the electrons is simulated under different magnetic field and density conditions. It is found that electrons can be accelerated to speeds capable of electron impact ionization for certain conditions. In the magnetically dominated case the energy distribution of the excited electrons shows that typically 1% of the electron population can exceed the initial electrostatic potential associated with the unbalanced ensemble of electrons
Balltracking: an highly efficient method for tracking flow fields
No full textWe present a method for tracking solar photospheric flows that is highly efficient, and demonstrate it using high resolution MDI continuum images. The method involves making a surface from the photospheric granulation data, and allowing many small floating tracers or balls to be moved around by the evolving granulation pattern. The results are tested against synthesised granulation with known flow fields and compared to the results produced by Local Correlation tracking (LCT). The results from this new method have similar accuracy to those produced by LCT. We also investigate the maximum spatial and temporal resolution of the velocity field that it is possible to extract, based on the statistical properties of the granulation data. We conclude that both methods produce results that are close to the maximum resolution possible from granulation data. The code runs very significantly faster than our similarly optimised LCT code, making real time applications on large data sets possible. The tracking method is not limited to photospheric flows, and will also work on any velocity field where there are visible moving features of known scale length
The SF-36: a simple, effective measure of mobility disability for epidemiological studies
No full textBackgroundMobility disability is a major problem in older people. Numerous scales exist for the measurement of disability but often these do not permit comparisons between study groups. The physical functioning (PF) domain of the established and widely used Short Form-36 (SF-36) questionnaire asks about limitations on ten mobility activities.ObjectivesTo describe prevalence of mobility disability in an elderly population, investigate the validity of the SF-36 PF score as a measure of mobility disability, and to establish age and sex specific norms for the PF score.MethodsWe explored relationships between the SF-36 PF score and objectively measured physical performance variables among 349 men and 280 women, 59-72 years of age, who participated in the Hertfordshire Cohort Study (HCS). Normative data were derived from the Health Survey for England (HSE) 1996.Results32% of men and 46% of women had at least some limitation in PF scale items. Poor SF-36 PF scores (lowest fifth of the gender-specific distribution) were related to: lower grip strength; longer timed-up-and-go, 3m walk, and chair rises test times in men and women; and lower quadriceps peak torque in women but not men. HSE normative data showed that median PF scores declined with increasing age in men and women.ConclusionOur results are consistent with the SF-36 PF score being a valid measure of mobility disability in epidemiological studies. This approach might be a first step towards enabling simple comparisons of prevalence of mobility disability between different studies of older people. The SF-36 PF score could usefully complement existing detailed schemes for classification of disability and it now requires validation against them
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