WorldWideScience

Sample records for bi-polar sunspot groups

  1. On two populations of sunspot groups

    International Nuclear Information System (INIS)

    Kuklin, G.V.

    1980-01-01

    The principal component method was applied studying the sunspot groups distribution in respect to the maximum area for the individual 11-year cycles 12 to 19 (Lopez Arroyo and Lahulla, 1974) and for the years 1900 to 1964 (Mandrykina, 1974). The existence of two populations of sunspot groups is confirmed. The variations of the importance parameter q, which determines the population shares, in the 80-, 22- and 11-year cycles are considered. The obtained maximal area distributions for populations I and II are approximated by linear combination of logarithmic-normal distributions, the subpopulations Ia, Ib, Ic by the most probable maximum areas of 22, 298 and 90 mvh, respectively, and the subpopulations IIa, IIb, IIc by the most probable maximal areas of 6, 142 and 754 mvh, respectively. The characteristic distinction between populations I and II is apparently the magnetic structure of the groups belonging to them (bipolar and unipolar ones). (author)

  2. Solar rotation and meridional motions derived from sunspot groups

    International Nuclear Information System (INIS)

    Tuominen, J.; Tuominen, I.; Kyroelaeinen, J.

    1982-01-01

    Latitudinal and longitudinal motions of sunspot groups have been studied using the positions of recurrent sunspot groups of 103 years published by Greenwich observatory. In order to avoid any limb effects, only positions close to the central meridian have been used. The data were divided into two parts: those belonging to the years around sunspot maxima and those belonging to the years around sunspot minima. Using several different criteria it was ascertained that sunspot groups show meridional motions and that their drift curves as a function of latitude are different around maxima and around minima. In addition, also the angular velocity, as a function of latitude, was found to be different around maxima and minima. (Auth.)

  3. Sunspots

    International Nuclear Information System (INIS)

    Moore, R.; Rabin, D.

    1985-01-01

    It is pointed out that the sun provides a close-up view of many astrophysically important phenomena, nearly all connected with the causes and effects of solar magnetic fields. The present article provides a review of the role of sunspots in a number of new areas of research. Connections with other solar phenomena are examined, taking into account flares, the solar magnetic cycle, global flows, luminosity variation, and global oscillations. A selective review of the structure and dynamic phenomena observed within sunspots is also presented. It is found that sunspots are usually contorted during the growth phase of an active region as magnetic field rapidly emerges and sunspots form, coalesce, and move past or even through each other. Attention is given to structure and flows, oscillations and waves, and plans for future studies. 145 references

  4. Sunspots

    International Nuclear Information System (INIS)

    Priest, E.R.

    1982-01-01

    The existence of sunspots has been known since ancient times, but it was only at the beginning of this century that they were found to be the sites of very strong magnetic fields, and it was realised that they represent the places where huge magnetic flux tubes burst through the solar surface. A theoretical understanding of sunspots has had to await the development of magnetohydrodynamics; however, even now, there is some controversy about answers to fundamental questions, such as: why is a sunspot cool, what is its equilibrium structure and how is it formed. Other topics that are discussed in the present chapter include magnetoconvection and the process of magnetic buoyancy whereby a flux tube deep within the Sun tends to rise towards the surface because it is lighter than its surroundings. Outside active regions the magnetic flux is not spread out uniformly to a weak field of a few Gauss, but instead it is mainly concentrated at supergranulation boundaries into intense flux tubes, whose properties are discussed. (Auth.)

  5. Studies of kinematic elements in two multicenter sunspot groups

    International Nuclear Information System (INIS)

    Korobova, Z.B.

    1983-01-01

    Some features of kinematic elements (KE) in two multicenter sunspot groups were studied using Tashkent full-disc white light heliograms. KE and morphological elements do not reveal any relationship. A KE coincides with a unipolar or multipolar spot or with part of a spot. It may also contain an extended stream including several spots. Relation of KE to large-scale photospheric magnetic fields is less clear. The line of polarity reversal is, in most cases, the deviding line between two adjacent KE. At the same time, a KE can contain spots of both polarities. Sunspot trajectories in the leading polarity regions show the best similarity. Interactions of KE are greatly influenced by the meridional drift. (author)

  6. Wings of the butterfly: Sunspot groups for 1826-2015

    Science.gov (United States)

    Leussu, R.; Usoskin, I. G.; Senthamizh Pavai, V.; Diercke, A.; Arlt, R.; Denker, C.; Mursula, K.

    2017-03-01

    The spatio-temporal evolution of sunspot activity, the so-called Maunder butterfly diagram, has been continously available since 1874 using data from the Royal Greenwich Observatory, extended by SOON network data after 1976. Here we present a new extended butterfly diagram of sunspot group occurrence since 1826, using the recently digitized data from Schwabe (1826-1867) and Spörer (1866-1880). The wings of the diagram are separated using a recently developed method based on an analysis of long gaps in sunspot group occurrence in different latitude bands. We define characteristic latitudes, corresponding to the start, end, and the largest extent of the wings (the F, L, and H latitudes). The H latitudes (30°-45°) are highly significantly correlated with the strength of the wings (quantified by the total sum of the monthly numbers of sunspot groups). The F latitudes (20°-30°) depict a weak tendency, especially in the southern hemisphere, to follow the wing strength. The L latitudes (2°-10°) show no clear relation to the wing strength. Overall, stronger cycle wings tend to start at higher latitudes and have a greater wing extent. A strong (5-6)-cycle periodic oscillation is found in the start and end times of the wings and in the overlap and gaps between successive wings of one hemisphere. While the average wing overlap is zero in the southern hemisphere, it is two to three months in the north. A marginally significant oscillation of about ten solar cycles is found in the asymmetry of the L latitudes. The new long database of butterfly wings provides new observational constraints to solar dynamo models that discuss the spatio-temporal distribution of sunspot occurrence over the solar cycle and longer. Digital data for Fig. 1 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A131

  7. The visibility function and its effect on the observed characteristics of sunspot groups. 1

    International Nuclear Information System (INIS)

    Kopecky, M.; Kuklin, G.V.; Starkova, I.P.

    1985-01-01

    The paper is an introductory study to a series dealing with the visibility function, the function of foreshortening of sunspot group areas, and with the effect of these functions on the results of the statistical processing of observations, which has to be taken into account in interpreting the results. A ''diagram of observational conditions'' is described, which enables a number of statistical problems of sunspot groups on the rotating Sun to be solved by computer modelling or by graphical methods. Examples are given of the use of this diagram in studying the distribution of the observed lifetime of sunspot groups with a given actual lifetime, of the decrease in the number of sunspot groups towards the limb of the solar disc, of the east-west asymmetry of sunspot group appearance and disappearance. (author)

  8. Sunspot number recalibration: The ~1840–1920 anomaly in the observer normalization factors of the group sunspot number

    Directory of Open Access Journals (Sweden)

    Cliver Edward W.

    2017-01-01

    Full Text Available We analyze the normalization factors (k′-factors used to scale secondary observers to the Royal Greenwich Observatory (RGO reference series of the Hoyt & Schatten (1998a, 1998b group sunspot number (GSN. A time series of these k′-factors exhibits an anomaly from 1841 to 1920, viz., the average k′-factor for all observers who began reporting groups from 1841 to 1883 is 1.075 vs. 1.431 for those who began from 1884 to 1920, with a progressive rise, on average, during the latter period. The 1883–1884 break between the two subintervals occurs precisely at the point where Hoyt and Schatten began to use a complex daisy-chaining method to scale observers to RGO. The 1841–1920 anomaly implies, implausibly, that the average sunspot observer who began from 1841 to 1883 was nearly as proficient at counting groups as mid-20th century RGO (for which k′ = 1.0 by definition while observers beginning during the 1884–1920 period regressed in group counting capability relative to those from the earlier interval. Instead, as shown elsewhere and substantiated here, RGO group counts increased relative to those of other long-term observers from 1874 to ~1915. This apparent inhomogeneity in the RGO group count series is primarily responsible for the increase in k′-factors from 1884 to 1920 and the suppression, by 44% on average, of the Hoyt and Schatten GSN relative to the original Wolf sunspot number (WSN before ~1885. Correcting for the early “learning curve” in the RGO reference series and minimizing the use of daisy-chaining rectifies the anomalous behavior of the k′-factor series. The resultant GSN time series (designated GSN* is in reasonable agreement with the revised WSN (SN*; Clette & Lefèvre 2016 and the backbone-based group sunspot number (RGS; Svalgaard & Schatten 2016 but significantly higher than other recent reconstructions (Friedli, personal communication, 2016; Lockwood et al. 2014a, 2014b; Usoskin et al. 2016a. This result

  9. On the chromospheric network structure around deVeloped groups of sunspots

    International Nuclear Information System (INIS)

    Kartashova, L.G.

    1980-01-01

    The chromospheric network structure around several developed groups of sunspots were studied on the basis of the observations in the Hsub(α) line. The resolution on the filtergrams was of 2. The following was found: 1) in the neighbourhood of the groups of sunspots 70% (from 870) of network cells stretch along fibrils direction (with accuracy 30 deg), and 15% of cells stretch approximately across that (at angles 70-90 deg); 2) out of the boundary of the main radial fibrils structure the groups of sunspots is often rounded by the system of network cells stretched approximately perpendicular to radial direction

  10. Occurrences of flares with type II and IV radio events in interacting sunspot groups in the course of revolutions

    International Nuclear Information System (INIS)

    Klimes, J.; Krivsky, L.

    1984-01-01

    Using data from 11-year solar cycle No. 20, it was found that flares with type II radio bursts are more than twice as frequent and flares with type IV bursts nearly twice as frequent in sunspot groups which developed close to each other or which merged in the course of revolutions than in isolated sunspot groups. With both types the occurrence of these flares is concentrated in the revolution of the so-called sunspot group interaction (their approximation, merging). (author)

  11. Differentiation without distancing. explaining bi-polarization of opinions without negative influence.

    Directory of Open Access Journals (Sweden)

    Michael Mäs

    Full Text Available Explanations of opinion bi-polarization hinge on the assumption of negative influence, individuals' striving to amplify differences to disliked others. However, empirical evidence for negative influence is inconclusive, which motivated us to search for an alternative explanation. Here, we demonstrate that bi-polarization can be explained without negative influence, drawing on theories that emphasize the communication of arguments as central mechanism of influence. Due to homophily, actors interact mainly with others whose arguments will intensify existing tendencies for or against the issue at stake. We develop an agent-based model of this theory and compare its implications to those of existing social-influence models, deriving testable hypotheses about the conditions of bi-polarization. Hypotheses were tested with a group-discussion experiment (N = 96. Results demonstrate that argument exchange can entail bi-polarization even when there is no negative influence.

  12. Differentiation without distancing. explaining bi-polarization of opinions without negative influence.

    Science.gov (United States)

    Mäs, Michael; Flache, Andreas

    2013-01-01

    Explanations of opinion bi-polarization hinge on the assumption of negative influence, individuals' striving to amplify differences to disliked others. However, empirical evidence for negative influence is inconclusive, which motivated us to search for an alternative explanation. Here, we demonstrate that bi-polarization can be explained without negative influence, drawing on theories that emphasize the communication of arguments as central mechanism of influence. Due to homophily, actors interact mainly with others whose arguments will intensify existing tendencies for or against the issue at stake. We develop an agent-based model of this theory and compare its implications to those of existing social-influence models, deriving testable hypotheses about the conditions of bi-polarization. Hypotheses were tested with a group-discussion experiment (N = 96). Results demonstrate that argument exchange can entail bi-polarization even when there is no negative influence.

  13. On the evolution of magnetic and velocity fields of an originating sunspot group

    International Nuclear Information System (INIS)

    Bachmann, G.

    1978-01-01

    Magnetographic measurements were made to derive longitudinal magnetic field strengths, line-of-sight velocities and the brightness distribution in an originating sunspot group. These results and photographs of the group are used to compare the evaluation of a relatively simple active region with our present ideas about the evolution of active regions in general. We found that the total magnetic flux increased from about 4 to 20x10 20 Mx over three days. The downward flow of gas in regions with stronger magnetic fields is formed only after the magnetic field has already been bipolar for two days. The maximum velocity always occurred in the main spots of the preceding and the subsequent parts of the sunspot group. Transformation into a flow pattern, which looks like Evershed motion, is observed in the main preceding sunspot after the formation of the penumbra. The generation of new active regions by concentration and amplification of magnetic fields, under the action of supergranulation flow in photospheric layers, cannot play an important role. On the contrary, the behaviour of the active region is in agreement with the conception of rising flux tubes, out of which the gas flows down. Our observations confirm that a magnetic field strength, leading to the generation of sunspots, is attained earlier in the preceding part of the originating active region than in its subsequent part. A series of subflares occurred in the active region, when short-lived small magnetic structure elements emerged in the larger bipolar magnetic field. (author)

  14. SOLAR CYCLE 24: CURIOUS CHANGES IN THE RELATIVE NUMBERS OF SUNSPOT GROUP TYPES

    International Nuclear Information System (INIS)

    Kilcik, A.; Yurchyshyn, V. B.; Ozguc, A.; Rozelot, J. P.

    2014-01-01

    Here, we analyze different sunspot group (SG) behaviors from the points of view of both the sunspot counts (SSCs) and the number of SGs, in four categories, for the time period of 1982 January-2014 May. These categories include data from simple (A and B), medium (C), large (D, E, and F), and decaying (H) SGs. We investigate temporal variations of all data sets used in this study and find the following results. (1) There is a very significant decrease in the large groups' SSCs and the number of SGs in solar cycle 24 (cycle 24) compared to cycles 21-23. (2) There is no strong variation in the decaying groups' data sets for the entire investigated time interval. (3) Medium group data show a gradual decrease for the last three cycles. (4) A significant decrease occurred in the small groups during solar cycle 23, while no strong changes show in the current cycle (cycle 24) compared to the previous ones. We confirm that the temporal behavior of all categories is quite different from cycle to cycle and it is especially flagrant in solar cycle 24. Thus, we argue that the reduced absolute number of the large SGs is largely, if not solely, responsible for the weak cycle 24. These results might be important for long-term space weather predictions to understand the rate of formation of different groups of sunspots during a solar cycle and the possible consequences for the long-term geomagnetic activity

  15. Sunspot Groups as Tracers of Sub Surface Processes .

    Indian Academy of Sciences (India)

    tribpo

    Owing to shortage of time I restrict this review to present a report on the work done by our group at Indian Institute of Astrophysics which fits the title of this colloquium and the title of my talk. I shall point out the clues given by these studies for modeling the cyclical evolution of solar magnetic fields, but I shall not report on the ...

  16. Initial phase of the development of sunspot groups and their forecast

    International Nuclear Information System (INIS)

    Berlyand, B.O.; Burov, V.A.; Stepanyan, N.N.

    1979-01-01

    Some characteristics of the initial phase of sunspot groups and their forecast have been considered. Experimental data on 340 sunspot groups were obtained in 1967-1969. It was found that oscillations of the magnetic flux in the groups indicate the possibility of the existence of typical periods (2 and 4 days) of the magnetic field development. Most of the groups appears in young plages. The probability of the protons injection from the young groups is very small. The typical time of the development of the proton centre is 10-30 days. The characteristics of the group on the first day of its existence are vaguely connected with the lifetime of the group. On the second and third days the magnetic characteristics (the summary magnetic flux and the number of the unipolar regions) have the highest correlation coefficient (approximately 70%) with the lifetime of the group. The problem of the group lifetime forecast was being solved with the pattern recognition technique. On the base of the second day observation of the existence of the group verification of the received forecast 14% exceeds the verification of the climatological forecast. The forecast of the Zurich class with the same technique is effective beginning with the fifth day of the group existence and the forecast of the flare activity of the group since the day of its appearance. The exceeding of the verification as compared with the climatological forecasts in these problems is 10% and 8% accordingly

  17. New reconstruction of the sunspot group numbers since 1739 using direct calibration and "backbone" methods

    Science.gov (United States)

    Chatzistergos, Theodosios; Usoskin, Ilya G.; Kovaltsov, Gennady A.; Krivova, Natalie A.; Solanki, Sami K.

    2017-06-01

    Context. The group sunspot number (GSN) series constitute the longest instrumental astronomical database providing information on solar activity. This database is a compilation of observations by many individual observers, and their inter-calibration has usually been performed using linear rescaling. There are multiple published series that show different long-term trends for solar activity. Aims: We aim at producing a GSN series, with a non-linear non-parametric calibration. The only underlying assumptions are that the differences between the various series are due to different acuity thresholds of the observers, and that the threshold of each observer remains constant throughout the observing period. Methods: We used a daisy chain process with backbone (BB) observers and calibrated all overlapping observers to them. We performed the calibration of each individual observer with a probability distribution function (PDF) matrix constructed considering all daily values for the overlapping period with the BB. The calibration of the BBs was carried out in a similar manner. The final series was constructed by merging different BB series. We modelled the propagation of errors straightforwardly with Monte Carlo simulations. A potential bias due to the selection of BBs was investigated and the effect was shown to lie within the 1σ interval of the produced series. The exact selection of the reference period was shown to have a rather small effect on our calibration as well. Results: The final series extends back to 1739 and includes data from 314 observers. This series suggests moderate activity during the 18th and 19th century, which is significantly lower than the high level of solar activity predicted by other recent reconstructions applying linear regressions. Conclusions: The new series provides a robust reconstruction, based on modern and non-parametric methods, of sunspot group numbers since 1739, and it confirms the existence of the modern grand maximum of solar

  18. TIME DISTRIBUTIONS OF LARGE AND SMALL SUNSPOT GROUPS OVER FOUR SOLAR CYCLES

    International Nuclear Information System (INIS)

    Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Cao, W.; Ozguc, A.; Rozelot, J. P.

    2011-01-01

    Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 20-23 by using Rome (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification), and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for solar cycle 22. In general, large SG numbers appear to reach their maximum in the middle of the solar cycle (phases 0.45-0.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum coronal mass ejection speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long-term variations of the total solar irradiance, which is thought to be an important factor in the Sun-Earth climate relationship.

  19. SMALL-SCALE AND GLOBAL DYNAMOS AND THE AREA AND FLUX DISTRIBUTIONS OF ACTIVE REGIONS, SUNSPOT GROUPS, AND SUNSPOTS: A MULTI-DATABASE STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Jaramillo, Andrés; Windmueller, John C.; Amouzou, Ernest C.; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Senkpeil, Ryan R. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Tlatov, Andrey G. [Kislovodsk Mountain Astronomical Station of the Pulkovo Observatory, Kislovodsk 357700 (Russian Federation); Nagovitsyn, Yury A. [Pulkovo Astronomical Observatory, Russian Academy of Sciences, St. Petersburg 196140 (Russian Federation); Pevtsov, Alexei A. [National Solar Observatory, Sunspot, NM 88349 (United States); Chapman, Gary A.; Cookson, Angela M. [San Fernando Observatory, Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States); Yeates, Anthony R. [Department of Mathematical Sciences, Durham University, South Road, Durham DH1 3LE (United Kingdom); Watson, Fraser T. [National Solar Observatory, Tucson, AZ 85719 (United States); Balmaceda, Laura A. [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina); DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Martens, Petrus C. H., E-mail: munoz@solar.physics.montana.edu [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States)

    2015-02-10

    In this work, we take advantage of 11 different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are better fitted by different distributions (as has been reported previously in the literature). However, we find that all our databases can be reconciled by the simple application of a proportionality constant, and that, in reality, different databases are sampling different parts of a composite distribution. This composite distribution is made up by linear combination of Weibull and log-normal distributions—where a pure Weibull (log-normal) characterizes the distribution of structures with fluxes below (above) 10{sup 21}Mx (10{sup 22}Mx). Additionally, we demonstrate that the Weibull distribution shows the expected linear behavior of a power-law distribution (when extended to smaller fluxes), making our results compatible with the results of Parnell et al. We propose that this is evidence of two separate mechanisms giving rise to visible structures on the photosphere: one directly connected to the global component of the dynamo (and the generation of bipolar active regions), and the other with the small-scale component of the dynamo (and the fragmentation of magnetic structures due to their interaction with turbulent convection)

  20. Variations and Regularities in the Hemispheric Distributions in Sunspot Groups of Various Classes

    Science.gov (United States)

    Gao, Peng-Xin

    2018-05-01

    The present study investigates the variations and regularities in the distributions in sunspot groups (SGs) of various classes in the northern and southern hemispheres from Solar Cycles (SCs) 12 to 23. Here, we use the separation scheme that was introduced by Gao, Li, and Li ( Solar Phys. 292, 124, 2017), which is based on A/U ( A is the corrected area of the SG, and U is the corrected umbral area of the SG), in order to separate SGs into simple SGs (A/U ≤ 4.5) and complex SGs (A/U > 6.2). The time series of Greenwich photoheliographic results from 1875 to 1976 (corresponding to complete SCs 12 - 20) and Debrecen photoheliographic data during the period 1974 - 2015 (corresponding to complete SCs 21 - 23) are used to show the distributions of simple and complex SGs in the northern and southern hemispheres. The main results we obtain are reported as follows: i) the larger of the maximum annual simple SG numbers in the two hemispheres and the larger of the maximum annual complex SG numbers in the two hemispheres occur in different hemispheres during SCs 12, 14, 18, and 19; ii) the relative changing trends of two curves - cumulative SG numbers in the northern and southern hemispheres - for simple SGs are different from those for complex SGs during SCs 12, 14, 18, and 21; and iii) there are discrepancies between the dominant hemispheres of simple and complex SGs for SCs 12, 14, 18, and 21.

  1. On sunspots

    CERN Document Server

    Galilei, Galileo; Reeves, Eileen; Helden, Albert van

    2010-01-01

    Galileo's telescopic discoveries, and especially his observation of sunspots, caused great debate in an age when the heavens were thought to be perfect and unchanging. Christoph Scheiner, a Jesuit mathematician, argued that sunspots were planets or moons crossing in front of the Sun. Galileo, on the other hand, countered that the spots were on or near the surface of the Sun itself, and he supported his position with a series of meticulous observations and mathematical demonstrations that eventually convinced even his rival.  On Sunspots collects the correspondenc

  2. A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

    Science.gov (United States)

    Ruždjak, Domagoj; Brajša, Roman; Sudar, Davor; Skokić, Ivica; Poljančić Beljan, Ivana

    2017-12-01

    The sunspot position published in the data bases of the Greenwich Photoheliographic Results (GPR), the US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and of the Debrecen Photoheliographic Data (DPD) in the period 1874 to 2016 were used to calculate yearly values of the solar differential-rotation parameters A and B. These differential-rotation parameters were compared with the solar-activity level. We found that the Sun rotates more differentially at the minimum than at the maximum of activity during the epoch 1977 - 2016. An inverse correlation between equatorial rotation and solar activity was found using the recently revised sunspot number. The secular decrease of the equatorial rotation rate that accompanies the increase in activity stopped in the last part of the twentieth century. It was noted that when a significant peak in equatorial rotation velocity is observed during activity minimum, the next maximum is weaker than the previous one.

  3. Essential features of long-term changes of areas and diameters of sunspot groups in solar activity cycles 12-24

    Science.gov (United States)

    Efimenko, V. M.; Lozitsky, V. G.

    2018-06-01

    We analyze the Greenwich catalog data on areas of sunspot groups of last thirteen solar cycles. Various parameters of sunspots are considered, namely: average monthly smoothed areas, maximum area for each year and equivalent diameters of groups of sunspots. The first parameter shows an exceptional power of the 19th cycle of solar activity, which appears here more contrastively than in the numbers of spots (that is, in Wolf's numbers). It was found that in the maximum areas of sunspot groups for a year there is a unique phenomenon: a short and high jump in the 18th cycle (in 1946-1947) that has no analogues in other cycles. We also studied the integral distributions for equivalent diameters and found the following: (a) the average value of the index of power-law approximation is 5.4 for the last 13 cycles and (b) there is reliable evidence of Hale's double cycle (about 44 years). Since this indicator reflects the dispersion of sunspot group diameters, the results obtained show that the convective zone of the Sun generates embryos of active regions in different statistical regimes which change with a cycle of about 44 years.

  4. Revised Sunspot Numbers and the Effects on Understanding the Sunspot Cycle

    Science.gov (United States)

    Hathaway, D. H.

    2014-12-01

    While sunspot numbers provide only limited information about the sunspot cycle, they provide that information for at least twice as many sunspot cycles as any other direct solar observation. In particular, sunspot numbers are available before, during, and immediately after the Maunder Minimum (1645-1715). The instruments and methods used to count sunspots have changed over the last 400+ years. This leads to systematic changes in the sunspot number that can mask, or artificially introduce, characteristics of the sunspot cycle. The most widely used sunspot number is the International (Wolf/Zurich) sunspot number which is now calculated at the Solar Influences Data Center in Brussels, Belgium. These numbers extend back to 1749. The Group sunspot number extends back to the first telescopic observations of the Sun in 1610. There are well-known and significant differences between these two numbers where they overlap. Recent work has helped us to understand the sources of these differences and has led to proposed revisions in the sunspot numbers. Independent studies now support many of these revisions. These revised sunspot numbers suggest changes to our understanding of the sunspot cycle itself and to our understanding of its connection to climate change.

  5. Differentiation without Distancing. Explaining Bi-Polarization of Opinions without Negative Influence

    NARCIS (Netherlands)

    Maes, Michael; Flache, Andreas

    2013-01-01

    Explanations of opinion bi-polarization hinge on the assumption of negative influence, individuals' striving to amplify differences to disliked others. However, empirical evidence for negative influence is inconclusive, which motivated us to search for an alternative explanation. Here, we

  6. Critical frequencies of the ionospheric F1 and F2 layers during the last four solar cycles: Sunspot group type dependencies

    Science.gov (United States)

    Yiǧit, Erdal; Kilcik, Ali; Elias, Ana Georgina; Dönmez, Burçin; Ozguc, Atila; Yurchshyn, Vasyl; Rozelot, Jean-Pierre

    2018-06-01

    The long term solar activity dependencies of ionospheric F1 and F2 regions' critical frequencies (f0F1 and f0F2) are analyzed for the last four solar cycles (1976-2015). We show that the ionospheric F1 and F2 regions have different solar activity dependencies in terms of the sunspot group (SG) numbers: F1 region critical frequency (f0F1) peaks at the same time with the small SG numbers, while the f0F2 reaches its maximum at the same time with the large SG numbers, especially during the solar cycle 23. The observed differences in the sensitivity of ionospheric critical frequencies to sunspot group (SG) numbers provide a new insight into the solar activity effects on the ionosphere and space weather. While the F1 layer is influenced by the slow solar wind, which is largely associated with small SGs, the ionospheric F2 layer is more sensitive to Coronal Mass Ejections (CMEs) and fast solar winds, which are mainly produced by large SGs and coronal holes. The SG numbers maximize during of peak of the solar cycle and the number of coronal holes peaks during the sunspot declining phase. During solar minimum there are relatively less large SGs, hence reduced CME and flare activity. These results provide a new perspective for assessing how the different regions of the ionosphere respond to space weather effects.

  7. Development of new bi-polar plates based on electrically conductive filled polymers for PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Jousse, F.; Salas, J.F.; Giroud, F. [C.E.A., Le Ripault, Monts (France); Icard, B.; Laurent, J.Y.; Serre Combe, P.

    2000-07-01

    In polymer electrolyte membrane fuel cell technology, the bi-polar plates are dedicated to: the current collection, the separation and distribution of gas (hydrogen and oxygen) at the cathode and the anode. To achieve these functions, bi-polar plate materials must satisfy the following properties: high conductivity (higher than 10 S/cm), high chemical resistance to acid and water, very low permeability to hydrogen (permeability < Pe{sup H2}{sub Nafion} (20 C) = 7.10{sup -17} m{sup 2}/Pa/s). Traditionally bi-polar plates have been designed with stainless steel or graphite. However, the cost of these plates are incompatible to transport applications, principally because of the gas channel machining step. Recently, we have noticed the work of T.M. Besmann [1] on the manufacturing of bi-polar plates based on carbon fibres and phenolic resin, processed by pyrolisis and densification on surface by a chemical vapour infiltration process. However, this kind of process seems too expensive and complex for the needs of the road electric transportation industry. Organic composites based on conductive chemical resistant fillers and processed by molding could be an alternative solution. Bi-polar plates requirements can be achieved by controlling and optimising experimental parameters such as the nature and morphology of fillers, the resin characteristics, and the process conditions. To avoid corrosion of the composite material, and then, the contamination of the cell, we have selected non metallic fillers, based on graphite or carbon black. (orig.)

  8. Sunspot Positions and Areas from Observations by Galileo Galilei

    Science.gov (United States)

    Vokhmyanin, M. V.; Zolotova, N. V.

    2018-02-01

    Sunspot records in the seventeenth century provide important information on the solar activity before the Maunder minimum, yielding reliable sunspot indices and the solar butterfly diagram. Galilei's letters to Cardinal Francesco Barberini and Marcus Welser contain daily solar observations on 3 - 11 May, 2 June - 8 July, and 19 - 21 August 1612. These historical archives do not provide the time of observation, which results in uncertainty in the sunspot coordinates. To obtain them, we present a method that minimizes the discrepancy between the sunspot latitudes. We provide areas and heliographic coordinates of 82 sunspot groups. In contrast to Sheiner's butterfly diagram, we found only one sunspot group near the Equator. This provides a higher reliability of Galilei's drawings. Large sunspot groups are found to emerge at the same longitude in the northern hemisphere from 3 May to 21 August, which indicates an active longitude.

  9. A Test of the Active-Day Fraction Method of Sunspot Group Number Calibration: Dependence on the Level of Solar Activity

    Science.gov (United States)

    Willamo, T.; Usoskin, I. G.; Kovaltsov, G. A.

    2018-04-01

    The method of active-day fraction (ADF) was proposed recently to calibrate different solar observers to standard observational conditions. The result of the calibration may depend on the overall level of solar activity during the observational period. This dependency is studied quantitatively using data of the Royal Greenwich Observatory by formally calibrating synthetic pseudo-observers to the full reference dataset. It is shown that the sunspot group number is precisely estimated by the ADF method for periods of moderate activity, may be slightly underestimated by 0.5 - 1.5 groups ({≤} 10%) for strong and very strong activity, and is strongly overestimated by up to 2.5 groups ({≤} 30%) for weak-to-moderate activity. The ADF method becomes inapplicable for the periods of grand minima of activity. In general, the ADF method tends to overestimate the overall level of activity and to reduce the long-term trends.

  10. Geometrical relationship of flare-generated solar wind structures to the magnetic axes of bipolar sunspot groups adjacent to their originating solar flares

    International Nuclear Information System (INIS)

    Ivanov, K.G.; Evdokimova, L.V.; Mikerina, N.V.

    1982-01-01

    Occurrences of interplanetary shock waves near the Earth after the powerful isolated flares of 1957-1978 are investigated. The close connection between the occurrences of shock waves and the positions of magnetic axes of bipolar groups of sunspots is suggested on the basis of a statistical study. The shock waves are principally observed when the Earth finds itself near the planes that are projected through the flares in parallel to the appropriate magnetic axes of the nearest bipolar groups. This regularity is interpreted as an indirect argument for a three-dimensional geometry for the interplanetary shock waves which, when projected on these flattened to corresponding planes, are traces of large circular arcs. The typical angular scales of isolated interplanetary shock waves are estimated as approx. equal to 150 0 and approx. equal to 30 0 parallel and perpendicular, respectively, to the magnetic axes correspondingly. (orig.)

  11. The sunspot databases of the Debrecen Observatory

    Science.gov (United States)

    Baranyi, Tünde; Gyori, Lajos; Ludmány, András

    2015-08-01

    We present the sunspot data bases and online tools available in the Debrecen Heliophysical Observatory: the DPD (Debrecen Photoheliographic Data, 1974 -), the SDD (SOHO/MDI-Debrecen Data, 1996-2010), the HMIDD (SDO/HMI-Debrecen Data, HMIDD, 2010-), the revised version of Greenwich Photoheliographic Data (GPR, 1874-1976) presented together with the Hungarian Historical Solar Drawings (HHSD, 1872-1919). These are the most detailed and reliable documentations of the sunspot activity in the relevant time intervals. They are very useful for studying sunspot group evolution on various time scales from hours to weeks. Time-dependent differences between the available long-term sunspot databases are investigated and cross-calibration factors are determined between them. This work has received funding from the European Community's Seventh Framework Programme (FP7/2012-2015) under grant agreement No. 284461 (eHEROES).

  12. Sunspots During the Maunder Minimum from Machina Coelestis by Hevelius

    Science.gov (United States)

    Carrasco, V. M. S.; Álvarez, J. Villalba; Vaquero, J. M.

    2015-10-01

    We revisited the sunspot observations published by Johannes Hevelius in his book Machina Coelestis (1679) corresponding to the period of 1653 - 1675 (just in the middle of the Maunder Minimum). We show detailed translations of the original Latin texts describing the sunspot records and provide the general context of these sunspot observations. From this source, we present an estimate of the annual values of the group sunspot number based only on the records that explicitly inform us of the presence or absence of sunspots. Although we obtain very low values of the group sunspot number, in accordance with a grand minimum of solar activity, these values are significantly higher in general than the values provided by Hoyt and Schatten ( Solar Phys. 179, 189, 1998) for the same period.

  13. Coordination failure caused by sunspots

    DEFF Research Database (Denmark)

    Beugnot, Julie; Gürgüç, Zeynep; Øvlisen, Frederik Roose

    2012-01-01

    on the efficient equilibrium, we consider sunspots as a potential reason for coordination failure. We conduct an experiment with a three player 2x2x2 game in which coordination on the efficient equilibrium is easy and should normally occur. In the control session, we find almost perfect coordination on the payoff......-dominant equilibrium, but in the sunspot treatment, dis-coordination is frequent. Sunspots lead to significant inefficiency, and we conclude that sunspots can indeed cause coordination failure....

  14. The Flares Associated with the Dynamics of the Sunspots K. M. ...

    Indian Academy of Sciences (India)

    tional theory of magnetic reconnection is briefly discussed. ... between changes in the sunspots' dynamics, emerging flux region, twisting of the field ... the eventual triggering of the flares is due to proper motion of the sunspots. Using .... rotation rates obtained from the daily motion of sunspot groups with respect to their life.

  15. Iwahashi Zenbei's Sunspot Drawings in 1793 in Japan

    Science.gov (United States)

    Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Toriumi, Shin; Shibata, Kazunari

    2018-01-01

    Three Japanese sunspot drawings associated with Iwahashi Zenbei (1756 - 1811) are shown here from contemporary manuscripts and woodprint documents with the relevant texts. We reveal the observational date of one of the drawings to be 26 August 1793, and the overall observations lasted for over a year. Moreover, we identify the observational site for the dated drawing as Fushimi in Japan. We then compare Zenbei's observations with the group sunspot number and the raw group count from the Sunspot Index and Long-term Solar Observations (SILSO) to reveal the context of the data, and we conclude that these drawings fill gaps in our understanding that are due to the fragmental sunspot observations around 1793. These drawings are important as a clue to evaluate astronomical knowledge of contemporary Japan in the late eighteenth century and are valuable as a non-European observation, considering that most sunspot observations up to the middle of the nineteenth century are from Europe.

  16. The sunspot cycle revisited

    International Nuclear Information System (INIS)

    Lomb, Nick

    2013-01-01

    The set of sunspot numbers observed since the invention of the telescope is one of the most studied time series in astronomy and yet it is also one of the most complex. Fourteen frequencies are found in the yearly mean sunspot numbers from 1700 to 2011using the Lomb-Scargle periodogram and prewhitening. All of the frequencies corresponding to shorter term periods can be matched with simple algebraic combinations of the frequency of the main 11-year period and the frequencies of the longer term periods in the periodogram. This is exactly what can be expected from amplitude and phase modulation of an 11.12-year periodicity by longer term variations. Similar, though not identical, results are obtained after correcting the sunspot number series as proposed by Svalgaard. On looking separately at the amplitude and phase modulation a clear relationship is found between the two modulations although this relationship has broken down for the last four solar cycles. The phase modulation implies that there is a definite underlying period for the solar cycle. Such a clock mechanism does seem to be a possibility in models of the solar dynamo incorporating a conveyor-belt-like meridional circulation between high polar latitudes and the equator.

  17. Sunspots sketches during the solar eclipses of 9th January and 29th December of 1777 in Mexico

    Science.gov (United States)

    Domínguez-Castro, Fernando; Gallego, María Cruz; Vaquero, José Manuel

    2017-06-01

    Two sunspot observations recorded by the Mexican Felipe de Zúñiga y Ontiveros have been revealed from a manuscript. One sunspot group was recorded on 9th January 1777 and four sunspot groups on 29th December 1777. Both records were taken during the observation of solar eclipses from Mexico City and their description also included sketches of the solar disk with sunspots. The sunspot group corresponding to 9th January was also observed by Erasmus Lievog. The observation on 29th December 1777 is the only record corresponding to this date.

  18. Oscillations and Waves in Sunspots

    Directory of Open Access Journals (Sweden)

    Elena Khomenko

    2015-11-01

    Full Text Available A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding.

  19. A study of the transient plasma potential in a pulsed bi-polar dc magnetron discharge

    International Nuclear Information System (INIS)

    Bradley, J W; Karkari, S K; Vetushka, A

    2004-01-01

    The temporal evolution of the plasma potential, V p , in a pulsed dc magnetron plasma has been determined using the emissive probe technique. The discharge was operated in the 'asymmetric bi-polar' mode, in which the discharge voltage changes polarity during part of the pulse cycle. The probe measurements, with a time-resolution of 20 ns or better, were made along a line above the racetrack, normal to the plane of the cathode target, for a fixed frequency (100 kHz), duty cycle (50%), argon pressure (0.74 Pa) and discharge power (583 W). At all the measured positions, V p was found to respond to the large and rapid changes in the cathode voltage, V d , during the different phases of the pulse cycle, with V p always more positive than V d . At a typical substrate position (>80 mm from the target), V p remains a few volts above the most positive surface in the discharge at all times. In the 'on' phase of the pulse, the measurements show a significant axial electric field is generated in the plasma, with the plasma potential dropping by a total of about 30 V over a distance of 70 mm, from the bulk plasma to a position close to the beginning of the cathode fall. This is consistent with measurements made in the dc magnetron. During the stable 'reverse' phase of the discharge, for distances greater than 18 mm from the target, the axial electric field is found to collapse, with V p elevated uniformly to about 3 V above V d . Between the target and this field-free region an ion sheath forms, and the current flowing to the target is still an ion current in this 'reverse' period. During the initial 200 ns of the voltage 'overshoot' phase (between 'on' and 'reverse' phases), V d reached a potential of +290 V; however, close to the target, V p was found to attain a much higher value, namely +378 V. Along the line of measurement, the axial electric field reverses in direction in this phase, and an electron current of up to 9 A flows to the target. The spatial and temporal

  20. The Recalibrated Sunspot Number: Impact on Solar Cycle Predictions

    Science.gov (United States)

    Clette, F.; Lefevre, L.

    2017-12-01

    Recently and for the first time since their creation, the sunspot number and group number series were entirely revisited and a first fully recalibrated version was officially released in July 2015 by the World Data Center SILSO (Brussels). Those reference long-term series are widely used as input data or as a calibration reference by various solar cycle prediction methods. Therefore, past predictions may now need to be redone using the new sunspot series, and methods already used for predicting cycle 24 will require adaptations before attempting predictions of the next cycles.In order to clarify the nature of the applied changes, we describe the different corrections applied to the sunspot and group number series, which affect extended time periods and can reach up to 40%. While some changes simply involve constant scale factors, other corrections vary with time or follow the solar cycle modulation. Depending on the prediction method and on the selected time interval, this can lead to different responses and biases. Moreover, together with the new series, standard error estimates are also progressively added to the new sunspot numbers, which may help deriving more accurate uncertainties for predicted activity indices. We conclude on the new round of recalibration that is now undertaken in the framework of a broad multi-team collaboration articulated around upcoming ISSI workshops. We outline the future corrections that can still be expected in the future, as part of a permanent upgrading process and quality control. From now on, future sunspot-based predictive models should thus be made more adaptable, and regular updates of predictions should become common practice in order to track periodic upgrades of the sunspot number series, just like it is done when using other modern solar observational series.

  1. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    International Nuclear Information System (INIS)

    McClintock, B. H.; Norton, A. A.; Li, J.

    2014-01-01

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators

  2. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A. [HEPL, Stanford University, Palo Alto, CA 94305 (United States); Li, J., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu, E-mail: jli@igpp.ucla.edu [Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2014-12-20

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators.

  3. On the correlation of longitudinal and latitudinal motions of sunspots

    International Nuclear Information System (INIS)

    Gilman, P.A.

    1984-01-01

    Using new measurements of positions of individual sunspots and sunspot groups obtained from 62 years of the Mt. Wilson white-light plate collection, we have recomputed the correlation between longitude and latitude motion. Our results for groups are similar to those of Ward (1965a) computed from the Greenwich record, but for individual spots the covariance is reduced by a factor of about 3 from the Ward values, though still of the same sign and still statistically significant. We conclude that there is a real correlation between longitude and latitude movement of individual spots, implying angular momentum transport toward the equator as inferred by Ward. The two thirds reduction in the covariance for individual spots as opposed to groups is probably due to certain properties of spot groups, as first pointed out in an unpublished manuscript by Leighton. (orig.)

  4. HELIOSEISMOLOGY OF A REALISTIC MAGNETOCONVECTIVE SUNSPOT SIMULATION

    International Nuclear Information System (INIS)

    Braun, D. C.; Birch, A. C.; Rempel, M.; Duvall, T. L. Jr.

    2012-01-01

    We compare helioseismic travel-time shifts measured from a realistic magnetoconvective sunspot simulation using both helioseismic holography and time-distance helioseismology, and measured from real sunspots observed with the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory. We find remarkable similarities in the travel-time shifts measured between the methodologies applied and between the simulated and real sunspots. Forward modeling of the travel-time shifts using either Born or ray approximation kernels and the sound-speed perturbations present in the simulation indicates major disagreements with the measured travel-time shifts. These findings do not substantially change with the application of a correction for the reduction of wave amplitudes in the simulated and real sunspots. Overall, our findings demonstrate the need for new methods for inferring the subsurface structure of sunspots through helioseismic inversions.

  5. Transparent Si–DLC coatings on metals with high repetition bi-polar pulses of a PBII system

    Energy Technology Data Exchange (ETDEWEB)

    Ikeyama, Masami, E-mail: ikeyama3@aist.go.jp; Sonoda, Tsutomu, E-mail: tsutomu.sonoda@aist.go.jp

    2013-07-15

    Diamond-like carbon (DLC) is widely used because of its good properties. However, the color of DLC is usually dark brown or black. Recently, we have made fairly transparent Si contained DLC (Si–DLC) coatings in visible light region. The fairly transparent Si–DLC was made by using our original bi-polar pulse type plasma based ion implantation (PBII) system, with recently introduced high slew rate pulse power supply. The colors of metal sample surface were uniformly changed as subdued red, yellow, subdued green and subdued blue or violet, with the change of Si–DLC coating’s thickness. The colors come from the interference between reflected lights at the surface of the Si–DLC coatings and the surface of the metal samples. The colors were also changed with the angle of glancing. Estimated refractive indexes show well agreements among almost all Si–DLC coatings, instead of the differences of coating conditions. Generally, the longer coating time or slower coating process makes the higher refractive index in near infrared region. Estimated band gap of a Si–DLC coating was about 1.5 eV. The developed Si–DLC coatings must be useful as not only protective but also decorative coatings.

  6. Application of the Markov chain approximation to the sunspot observations

    International Nuclear Information System (INIS)

    Onal, M.

    1988-01-01

    The positions of the 13,588 sunspot groups observed during the cycle of 1950-1960 at the Istanbul University Observatory have been corrected for the effect of differential rotation. The evolution probability of a sunspot group to the other one in the same region have been determined. By using the Markov chain approximation, the types of these groups and their transition probabilities during the following activity cycle (1950-1960), and the concentration of active regions during 1950-1960 have been estimated. The transition probabilities from the observations of the activity cycle 1960-1970 have been compared with the predicted transition probabilities and a good correlation has been noted. 5 refs.; 2 tabs

  7. Evolution of the Sunspot Number and Solar Wind B Time Series

    Science.gov (United States)

    Cliver, Edward W.; Herbst, Konstantin

    2018-03-01

    The past two decades have witnessed significant changes in our knowledge of long-term solar and solar wind activity. The sunspot number time series (1700-present) developed by Rudolf Wolf during the second half of the 19th century was revised and extended by the group sunspot number series (1610-1995) of Hoyt and Schatten during the 1990s. The group sunspot number is significantly lower than the Wolf series before ˜1885. An effort from 2011-2015 to understand and remove differences between these two series via a series of workshops had the unintended consequence of prompting several alternative constructions of the sunspot number. Thus it has been necessary to expand and extend the sunspot number reconciliation process. On the solar wind side, after a decade of controversy, an ISSI International Team used geomagnetic and sunspot data to obtain a high-confidence time series of the solar wind magnetic field strength (B) from 1750-present that can be compared with two independent long-term (> ˜600 year) series of annual B-values based on cosmogenic nuclides. In this paper, we trace the twists and turns leading to our current understanding of long-term solar and solar wind activity.

  8. Self-affinity and nonextensivity of sunspots

    International Nuclear Information System (INIS)

    Moret, M.A.

    2014-01-01

    In this paper we study the time series of sunspots by using two different approaches, analyzing its self-affine behavior and studying its distribution. The long-range correlation exponent α has been calculated via Detrended Fluctuation Analysis and the power law vanishes to values greater than 11 years. On the other hand, the distribution of the sunspots obeys a q-exponential decay that suggests a non-extensive behavior. This observed characteristic seems to take an alternative interpretation of the sunspots dynamics. The present findings suggest us to propose a dynamic model of sunspots formation based on a nonlinear Fokker–Planck equation. Therefore its dynamic process follows the generalized thermostatistical formalism.

  9. Featured Image: Bright Dots in a Sunspot

    Science.gov (United States)

    Kohler, Susanna

    2018-03-01

    This image of a sunspot, located in in NOAA AR 12227, was captured in December 2014 by the 0.5-meter Solar Optical Telescope on board the Hinode spacecraft. This image was processed by a team of scientists led by Rahul Yadav (Udaipur Solar Observatory, Physical Research Laboratory Dewali, India) in order to examine the properties of umbral dots: transient, bright features observed in the umbral region (the central, darkest part) of a sunspot. By exploring these dots, Yadav and collaborators learned how their properties relate to the large-scale properties of the sunspots in which they form for instance, how do the number, intensities, or filling factors of dots relate to the size of a sunspots umbra? To find out more about the authors results, check out the article below.Sunspot in NOAA AR 11921. Left: umbralpenumbral boundary. Center: the isolated umbra from the sunspot. Right: The umbra with locations of umbral dots indicated by yellow plus signs. [Adapted from Yadav et al. 2018]CitationRahul Yadav et al 2018 ApJ 855 8. doi:10.3847/1538-4357/aaaeba

  10. Applications and limitations of micro-XCT imaging in the studies of Permian radiolarians: A new genus with bi-polar main spines

    Directory of Open Access Journals (Sweden)

    Yifan Xiao

    2017-09-01

    Full Text Available Microfocus X-ray Computed Tomography (micro-XCT has been employed recently in radiolarian studies, though so far primarily to generate high quality tomographic images. Although micro-XCT technique cannot always produce high-quality tomographic images, it frequently can provide valuable information on the internal structure of spongy polycystines. Here we employ micro-XCT to understand internal skeletal structures of several Permian specimens of polycystine radiolarians. Structural inferences from micro-XCT images are compared to images of the same specimens made with SEM and transmitted light microscopy (TLM. The utility of micro-XCT for imaging internal structures is first confirmed by examining the spongy, flat, four-spined species Tetraspongodiscus stauracanthus. Micro-XCT method is then used to examine the internal structures of a spherical to elliptical polycystine with two bi-polar main spines, Dalongicaepa bipolaris Xiao and Suzuki gen. et sp. nov., from the Dalong Formation (Changhsingian of South China. The new genus is characterized by four to seven densely concentric shells with a large spherical hollow in the center and two cylindrical spines at both poles of the cortical shell, and belongs to the family Spongotortilispinidae. Spherical to elliptical polycystines with bi-polar main spines are similar in external appearance, and their phylogenetic relationships are only determinable by examination of the internal structures. We therefore analyzed all Permian and Mesozoic spherical to elliptical polycystines with bi-polar main spines showing internal structures, using cluster analysis to measure similarity. The results show distinctive differences in internal structures and suggest that family level relationships should be revised in the future.

  11. The Strongest Magnetic Field in Sunspots

    Science.gov (United States)

    Okamoto, J.; Sakurai, T.

    2017-12-01

    Sunspots are concentrations of magnetic fields on the solar surface. Generally, the strongest magnetic field in each sunspot is located in the dark umbra in most cases. A typical field strength in sunspots is around 3,000 G. On the other hand, some exceptions also have been found in complex sunspots with bright regions such as light bridges that separate opposite polarity umbrae, for instance with a strength of 4,300 G. However, the formation mechanism of such strong fields outside umbrae is still puzzling. Here we report an extremely strong magnetic field in a sunspot, which was located in a bright region sandwiched by two opposite-polarity umbrae. The strength is 6,250 G, which is the largest ever observed since the discovery of magnetic field on the Sun in 1908 by Hale. We obtained 31 scanned maps of the active region observed by Hinode/SOT/SP with a cadence of 3 hours over 5 days (February 1-6, 2014). Considering the spatial and temporal evolution of the vector magnetic field and the Doppler velocity in the bright region, we suggested that this strong field region was generated as a result of compression of one umbra pushed by the outward flow from the other umbra (Evershed flow), like the subduction of the Earth's crust in plate tectonics.

  12. On the insignificance of Herschel's sunspot correlation

    Science.gov (United States)

    Love, Jeffrey J.

    2013-08-01

    We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is "statistically significant." On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are "insignificant." Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.

  13. Sunspot drawings handwritten character recognition method based on deep learning

    Science.gov (United States)

    Zheng, Sheng; Zeng, Xiangyun; Lin, Ganghua; Zhao, Cui; Feng, Yongli; Tao, Jinping; Zhu, Daoyuan; Xiong, Li

    2016-05-01

    High accuracy scanned sunspot drawings handwritten characters recognition is an issue of critical importance to analyze sunspots movement and store them in the database. This paper presents a robust deep learning method for scanned sunspot drawings handwritten characters recognition. The convolution neural network (CNN) is one algorithm of deep learning which is truly successful in training of multi-layer network structure. CNN is used to train recognition model of handwritten character images which are extracted from the original sunspot drawings. We demonstrate the advantages of the proposed method on sunspot drawings provided by Chinese Academy Yunnan Observatory and obtain the daily full-disc sunspot numbers and sunspot areas from the sunspot drawings. The experimental results show that the proposed method achieves a high recognition accurate rate.

  14. Planetary tides during the Maunder sunspot minimum

    International Nuclear Information System (INIS)

    Smythe, C.M.; Eddy, J.A.

    1977-01-01

    Sun-centered planetary conjunctions and tidal potentials are here constructed for the AD1645 to 1715 period of sunspot absence, referred to as the 'Maunder Minimum'. These are found to be effectively indistinguishable from patterns of conjunctions and power spectra of tidal potential in the present era of a well established 11 year sunspot cycle. This places a new and difficult restraint on any tidal theory of sunspot formation. Problems arise in any direct gravitational theory due to the apparently insufficient forces and tidal heights involved. Proponents of the tidal hypothesis usually revert to trigger mechanisms, which are difficult to criticise or test by observation. Any tidal theory rests on the evidence of continued sunspot periodicity and the substantiation of a prolonged period of solar anomaly in the historical past. The 'Maunder Minimum' was the most drastic change in the behaviour of solar activity in the last 300 years; sunspots virtually disappeared for a 70 year period and the 11 year cycle was probably absent. During that time, however, the nine planets were all in their orbits, and planetary conjunctions and tidal potentials were indistinguishable from those of the present era, in which the 11 year cycle is well established. This provides good evidence against the tidal theory. The pattern of planetary tidal forces during the Maunder Minimum was reconstructed to investigate the possibility that the multiple planet forces somehow fortuitously cancelled at the time, that is that the positions of the slower moving planets in the 17th and early 18th centuries were such that conjunctions and tidal potentials were at the time reduced in number and force. There was no striking dissimilarity between the time of the Maunder Minimum and any period investigated. The failure of planetary conjunction patterns to reflect the drastic drop in sunspots during the Maunder Minimum casts doubt on the tidal theory of solar activity, but a more quantitative test

  15. Sunspot activity and influenza pandemics: a statistical assessment of the purported association.

    Science.gov (United States)

    Towers, S

    2017-10-01

    Since 1978, a series of papers in the literature have claimed to find a significant association between sunspot activity and the timing of influenza pandemics. This paper examines these analyses, and attempts to recreate the three most recent statistical analyses by Ertel (1994), Tapping et al. (2001), and Yeung (2006), which all have purported to find a significant relationship between sunspot numbers and pandemic influenza. As will be discussed, each analysis had errors in the data. In addition, in each analysis arbitrary selections or assumptions were also made, and the authors did not assess the robustness of their analyses to changes in those arbitrary assumptions. Varying the arbitrary assumptions to other, equally valid, assumptions negates the claims of significance. Indeed, an arbitrary selection made in one of the analyses appears to have resulted in almost maximal apparent significance; changing it only slightly yields a null result. This analysis applies statistically rigorous methodology to examine the purported sunspot/pandemic link, using more statistically powerful un-binned analysis methods, rather than relying on arbitrarily binned data. The analyses are repeated using both the Wolf and Group sunspot numbers. In all cases, no statistically significant evidence of any association was found. However, while the focus in this particular analysis was on the purported relationship of influenza pandemics to sunspot activity, the faults found in the past analyses are common pitfalls; inattention to analysis reproducibility and robustness assessment are common problems in the sciences, that are unfortunately not noted often enough in review.

  16. Diode laser heterodyne observations of silicon monoxide in sunspots - A test of three sunspot models

    Science.gov (United States)

    Glenar, D. A.; Deming, D.; Jennings, D. E.; Kostiuk, T.; Mumma, M. J.

    1983-01-01

    Absorption features from the 8 micron SiO fundamental (upsilon = 1-0) and hot bands (upsilon = 2-1) have been observed in sunspots at sub-Doppler resolution using a ground-based tunable diode laser heterodyne spectrometer. The observed line widths suggest an upper limit of 0.5 km/s for the microturbulent velocity in sunspot umbrae. Since the silicon monoxide abundance is very sensitive to sunspot temperature, the measured equivalent widths permit an unambiguous determination of the temperature-pressure relation in the upper layers of the umbral atmosphere. In the region of SiO line formation (log P sub g = 3.0-4.5), the results support the sunspot model suggested by Stellmacher and Wiehr (1970).

  17. On the structure of small sunspots

    International Nuclear Information System (INIS)

    Ringnes, T.S.

    1984-01-01

    The smallest and most short-lived sunspots are decribed differently at the observatories in Zuerich and Greenwich. These differences which seem to originate both from the observing procedure and from the definitions of penumbra and umbra adopted, are further discussed

  18. Nature's third cycle a story of sunspots

    CERN Document Server

    Choudhuri, Arnab Rai

    2015-01-01

    The cycle of day and night and the cycle of seasons are two familiar natural cycles around which many human activities are organized. But is there a third natural cycle of importance for us humans? On 13 March 1989, six million people in Canada went without electricity for many hours: a large explosion on the sun was discovered as the cause of this blackout. Such explosions occur above sunspots, dark features on the surface of the Sun that have been observed through telescopes since the time of Galileo. The number of sunspots has been found to wax and wane over a period of 11 years. Although this cycle was discovered less than two centuries ago, it is becoming increasingly important for us as human society becomes more dependent on technology. For nearly a century after its discovery, the cause of the sunspot cycle remained completely shrouded in mystery. The 1908 discovery of strong magnetic fields in sunspots made it clear that the 11-year cycle is the magnetic cycle of the sun. It is only during the last ...

  19. Bi-polarized translation of ascidian maternal mRNA determinant pem-1 associated with regulators of the translation machinery on cortical Endoplasmic Reticulum (cER).

    Science.gov (United States)

    Paix, Alexandre; Le Nguyen, Phuong Ngan; Sardet, Christian

    2011-09-01

    Polarized cortical mRNA determinants such as maternal macho-1 and pem-1 in ascidians, like budding yeast mating factor ASH1 reside on the cER-mRNA domain a subdomain of cortical Endoplasmic Reticulum(ER) and are translated in its vicinity. Using high resolution imaging and isolated cortical fragments prepared from eggs and embryos we now find that macho-1 and pem-1 RNAs co-localize with phospho-protein regulators of translation initiation (MnK/4EBP/S6K). Translation of cortical pem-1 RNA follows its bi-polarized relocalization. About 10 min after fertilization or artificial activation with a calcium ionophore, PEM1 protein is detected in the vegetal cortex in the vicinity of pem-1 RNA. About 40 min after fertilization-when pem-1 RNA and P-MnK move to the posterior pole-PEM1 protein remains in place forming a network of cortical patches anchored at the level of the zygote plasma membrane before disappearing. Cortical PEM1 protein is detected again at the 4 cell stage in the posterior centrosome attracting body (CAB) region where the cER-mRNA domain harboring pem-1/P-MnK/P-4EBP/P-S6K is concentrated. Bi-polarized PEM1 protein signals are not detected when pem-1 morpholinos are injected into eggs or zygotes or when MnK is inhibited. We propose that localized translation of the pem-1 RNA determinant is triggered by the fertilization/calcium wave and that the process is controlled by phospho-protein regulators of translation initiation co-localized with the RNA determinant on a sub-domain of the cortical Endoplasmic Reticulum. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Sunspot splitting triggering an eruptive flare

    Science.gov (United States)

    Louis, Rohan E.; Puschmann, Klaus G.; Kliem, Bernhard; Balthasar, Horst; Denker, Carsten

    2014-02-01

    Aims: We investigate how the splitting of the leading sunspot and associated flux emergence and cancellation in active region NOAA 11515 caused an eruptive M5.6 flare on 2012 July 2. Methods: Continuum intensity, line-of-sight magnetogram, and dopplergram data of the Helioseismic and Magnetic Imager were employed to analyse the photospheric evolution. Filtergrams in Hα and He I 10830 Å of the Chromospheric Telescope at the Observatorio del Teide, Tenerife, track the evolution of the flare. The corresponding coronal conditions were derived from 171 Å and 304 Å images of the Atmospheric Imaging Assembly. Local correlation tracking was utilized to determine shear flows. Results: Emerging flux formed a neutral line ahead of the leading sunspot and new satellite spots. The sunspot splitting caused a long-lasting flow towards this neutral line, where a filament formed. Further flux emergence, partly of mixed polarity, as well as episodes of flux cancellation occurred repeatedly at the neutral line. Following a nearby C-class precursor flare with signs of interaction with the filament, the filament erupted nearly simultaneously with the onset of the M5.6 flare and evolved into a coronal mass ejection. The sunspot stretched without forming a light bridge, splitting unusually fast (within about a day, complete ≈6 h after the eruption) in two nearly equal parts. The front part separated strongly from the active region to approach the neighbouring active region where all its coronal magnetic connections were rooted. It also rotated rapidly (by 4.9° h-1) and caused significant shear flows at its edge. Conclusions: The eruption resulted from a complex sequence of processes in the (sub-)photosphere and corona. The persistent flows towards the neutral line likely caused the formation of a flux rope that held the filament. These flows, their associated flux cancellation, the emerging flux, and the precursor flare all contributed to the destabilization of the flux rope. We

  1. Vertical gradients of sunspot magnetic fields

    Science.gov (United States)

    Hagyard, M. J.; Teuber, D.; West, E. A.; Tandberg-Hanssen, E.; Henze, W., Jr.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; Woodgate, B. E.

    1983-01-01

    The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.

  2. Probing sunspots with two-skip time-distance helioseismology

    Science.gov (United States)

    Duvall, Thomas L., Jr.; Cally, Paul S.; Przybylski, Damien; Nagashima, Kaori; Gizon, Laurent

    2018-06-01

    Context. Previous helioseismology of sunspots has been sensitive to both the structural and magnetic aspects of sunspot structure. Aims: We aim to develop a technique that is insensitive to the magnetic component so the two aspects can be more readily separated. Methods: We study waves reflected almost vertically from the underside of a sunspot. Time-distance helioseismology was used to measure travel times for the waves. Ray theory and a detailed sunspot model were used to calculate travel times for comparison. Results: It is shown that these large distance waves are insensitive to the magnetic field in the sunspot. The largest travel time differences for any solar phenomena are observed. Conclusions: With sufficient modeling effort, these should lead to better understanding of sunspot structure.

  3. Photoelectric observations of propagating sunspot oscillations

    International Nuclear Information System (INIS)

    Lites, B.W.; White, O.R.; Packman, D.

    1982-01-01

    The Sacramento Park Observatory Vacuum Tower Telescope and diode array were used to make repeated intensity and velocity images of a large, isolated sunspot in both a chromospheric (lambda8542 Ca II) and a photospheric (lambda5576 Fe I) line. The movie of the digital data for the chromospheric line shows clearly a relationship between the propagating umbral disturbances and the running penumbral waves. The velocities for transverse propagating of the umbral and penumbral disturbances are 60--70 km s -1 and 20--35 km s -1 , respectively. Power spectra of the oscillations show a sharp peak at a period of about 170 s in both the velocity and intensity signals. The rms velocity fluctuation of this power peak is 0.26 km s -1 . The oscillations at any given point in the sunspot are very regular, and the phase relationship between the velocity and intensity of the chromospheric oscillations is radically different than that for the quiet Sun. Our preliminary interpretation of the phase relationship involves acoustic waves with wave vector directed downwards along the magnetic field lines; however, this interpretation relies on assumptions involved in the data reduction scheme. The mechanical energy flux carried by the observed umbral disturbances does not appear to be a significant contributor to the overall energy budget of the sunspot or the surrounding active region

  4. Corona magnetic field over sunspots estimated by m-wave observation

    International Nuclear Information System (INIS)

    Kurihara, Masahiro

    1974-01-01

    The shape of the magnetic field in corona was estimated from the observation of the type I storm occurred in the last decade of August, 1971. It was found from the observation with a 160 MHz interferometer at Mt. Nobeyama that at most three storm sources, which are called radio wave source, were produced. The radio wave sources were fixed above sunspots. The height of the radio wave sources was estimated to be 0.45 R from the photosphere. The sunspots under the radio wave sources can be classified to four sub-groups. Weakening of the magnetic field on the photosphere was found from the reduction of the area of some sub-group. The relation between the activity of type I storm and the intensity of the magnetic field of sunspots is qualitatively suggested. It is considered that the radio wave sources and the sunspots were connected by common magnetic force lines. The probable magnetic field in corona was presumed and is shown in a figure. An interesting point is that the direction of magnetic force lines inclined by about 30 0 outward to the vertical line to the photosphere surface. (Kato, T.)

  5. Statistics of the largest sunspot and facular areas per solar cycle

    International Nuclear Information System (INIS)

    Willis, D.M.; Kabasakal Tulunay, Y.

    1979-01-01

    The statistics of extreme values is used to investigate the statistical properties of the largest areas sunspots and photospheric faculae per solar cycle. The largest values of the synodic-solar-rotation mean areas of umbrae, whole spots and faculae, which have been recorded for nine solar cycles, are each shown to comply with the general form of the extreme value probability function. Empirical expressions are derived for the three extreme value populations from which the characteristic statistical parameters, namely the mode, median, mean and standard deviation, can be calculated for each population. These three extreme value populations are also used to find the expected ranges of the extreme areas in a group of solar cycles as a function of the number of cycles in the group. The extreme areas of umbrae and whole spots have a dispersion comparable to that found by Siscoe for the extreme values of sunspot number, whereas the extreme areas of faculae have a smaller dispersion which is comparable to that found by Siscoe for the largest geomagnetic storm per solar cycle. The expected range of the largest sunspot area per solar cycle for a group of one hundred cycles appears to be inconsistent with the existence of the prolonged periods of sunspot minima that have been inferred from the historical information on solar variability. This inconsistency supports the contention that there are temporal changes of solar-cycle statistics during protracted periods of sunspot minima (or maxima). Indeed, without such temporal changes, photospheric faculae should have been continually observable throughout the lifetime of the Sun. (orig.)

  6. Tracking the Magnetic Flux in and Around Sunspots

    Energy Technology Data Exchange (ETDEWEB)

    Sheeley, N. R. Jr.; Stauffer, J. R.; Thomassie, J. C.; Warren, H. P., E-mail: solsheeley@verizon.net, E-mail: harry.warren@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

    2017-02-10

    We have developed a procedure for tracking sunspots observed by the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory and for making curvature-corrected space/time maps of the associated line-of-sight magnetic field and continuum intensity. We apply this procedure to 36 sunspots, each observed continuously for nine days around its central meridian passage time, and find that the proper motions separate into two distinct components depending on their speeds. Fast (∼3–5 km s{sup −1}) motions, comparable to Evershed flows, are produced by weak vertical fluctuations of the horizontal canopy field and recur on a timescale of 12–20 min. Slow (∼0.3–0.5 km s{sup −1}) motions diverge from a sunspot-centered ring whose location depends on the size of the sunspot, occurring in the mid-penumbra for large sunspots and at the outer edge of the penumbra for small sunspots. The slow ingoing features are contracting spokes of a quasi-vertical field of umbral polarity. These inflows disappear when the sunspot loses its penumbra, and may be related to inward-moving penumbral grain. The slow outgoing features may have either polarity depending on whether they originate from quasi-vertical fields of umbral polarity or from the outer edge of the canopy. When a sunspot decays, the penumbra and canopy disappear, and the moat becomes filled with slow outflows of umbral polarity. We apply our procedure to decaying sunspots, to long-lived sunspots, and to numerical simulations of a long-lived sunspot by Rempel.

  7. Towards a first detailed reconstruction of sunspot information over the last 150 years

    Science.gov (United States)

    Lefevre, Laure; Clette, Frédéric

    2013-04-01

    With four centuries of solar evolution, the International Sunspot Number (SSN) forms the longest solar time series currently available. It provides an essential reference for understanding and quantifying how the solar output has varied over decades and centuries and thus for assessing the variations of the main natural forcing on the Earth climate. For such a quantitative use, this unique time-series must be closely monitored for any possible biases and drifts. This is the main objective of the Sunspot Workshops organized jointly by the National Solar Observatory (NSO) and the Royal Observatory of Belgium (ROB) since 2010. Here, we will report about some recent outcomes of past workshops, like diagnostics of scaling errors and their proposed corrections, or the recent disagreement between the sunspot sumber and other solar indices like the 10.7cm radio flux. Our most recent analyses indicate that while part of this divergence may be due to a calibration drift in the SSN, it also results from an intrinsic change in the global magnetic parameters of sunspots and solar active regions, suggesting a possible transition to a new activity regime. Going beyond the SSN series, in the framework of the SOTERIA, TOSCA and SOLID projects, we produced a survey of all existing catalogs providing detailed sunspot information and we also located different primary solar images and drawing collections that can be exploitable to complement the existing catalogs (COMESEP project). These are first steps towards the construction of a multi-parametric time series of multiple sunspot group properties over at least the last 150 years, allowing to reconstruct and extend the current 1-D SSN series. By bringing new spatial, morphological and evolutionary information, such a data set should bring major advances for the modeling of the solar dynamo and solar irradiance. We will present here the current status of this work. The catalog now extends over the last 3 cycles (Lefevre & Clette 2011

  8. Towards the automatic detection and analysis of sunspot rotation

    Science.gov (United States)

    Brown, Daniel S.; Walker, Andrew P.

    2016-10-01

    Torsional rotation of sunspots have been noted by many authors over the past century. Sunspots have been observed to rotate up to the order of 200 degrees over 8-10 days, and these have often been linked with eruptive behaviour such as solar flares and coronal mass ejections. However, most studies in the literature are case studies or small-number studies which suffer from selection bias. In order to better understand sunspot rotation and its impact on the corona, unbiased large-sample statistical studies are required (including both rotating and non-rotating sunspots). While this can be done manually, a better approach is to automate the detection and analysis of rotating sunspots using robust methods with well characterised uncertainties. The SDO/HMI instrument provide long-duration, high-resolution and high-cadence continuum observations suitable for extracting a large number of examples of rotating sunspots. This presentation will outline the analysis of SDI/HMI data to determine the rotation (and non-rotation) profiles of sunspots for the complete duration of their transit across the solar disk, along with how this can be extended to automatically identify sunspots and initiate their analysis.

  9. The EUV Spectrum of Sunspot Plumes Observed by SUMER on ...

    Indian Academy of Sciences (India)

    tribpo

    Abstract. We present results from sunspot observations obtained by. SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions ...

  10. Fractal Dimension and Maximum Sunspot Number in Solar Cycle

    Directory of Open Access Journals (Sweden)

    R.-S. Kim

    2006-09-01

    Full Text Available The fractal dimension is a quantitative parameter describing the characteristics of irregular time series. In this study, we use this parameter to analyze the irregular aspects of solar activity and to predict the maximum sunspot number in the following solar cycle by examining time series of the sunspot number. For this, we considered the daily sunspot number since 1850 from SIDC (Solar Influences Data analysis Center and then estimated cycle variation of the fractal dimension by using Higuchi's method. We examined the relationship between this fractal dimension and the maximum monthly sunspot number in each solar cycle. As a result, we found that there is a strong inverse relationship between the fractal dimension and the maximum monthly sunspot number. By using this relation we predicted the maximum sunspot number in the solar cycle from the fractal dimension of the sunspot numbers during the solar activity increasing phase. The successful prediction is proven by a good correlation (r=0.89 between the observed and predicted maximum sunspot numbers in the solar cycles.

  11. Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

    Directory of Open Access Journals (Sweden)

    Rolf Schlichenmaier

    2011-09-01

    Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

  12. An essay on sunspots and solar flares

    International Nuclear Information System (INIS)

    Akasofu, S.-I.

    1984-01-01

    The presently prevailing theories of sunspots and solar flares rely on the hypothetical presence of magnetic flux tubes beneath the photosphere and the two subsequent hypotheses, their emergence above the photosphere and explosive magnetic reconnection, converting magnetic energy carried by the flux tubes for solar flare energy. In this paper, attention is paid to the fact that there are large-scale magnetic fields which divide the photosphere into positive and negative (line-of-sight) polarity regions and that they are likely to be more fundamental than sunspot fields, as emphasized most recently by McIntosh. A new phenomenological model of the sunspot pair formation is then constructed by considering an amplification process of these large-scale fields near their boundaries by shear flows, including localized vortex motions. The amplification results from a dynamo process associated with such vortex flows and the associated convergence flow in the large-scale fields. This dynamo process generates also some of the familiar ''force-free'' fields or the ''sheared'' magnetic fields in which the magnetic field-aligned currents are essential. Upward field-aligned currents generated by the dynamo process are carried by downward streaming electrons which are expected to be accelerated by an electric potential structure; a similar structure is responsible for accelerating auroral electrons in the magnetosphere. Depending on the magnetic field configuration and the shear flows, the current-carrying electrons precipitate into different geometrical patterns, causing circular flares, umbral flares, two-ribbon flares, etc. Thus, it is suggested that ''low temperature flares'' are directly driven by the photospheric dynamo process. (author)

  13. Fully Automated Sunspot Detection and Classification Using SDO HMI Imagery in MATLAB

    Science.gov (United States)

    2014-03-27

    initiating the java program scripted to communicate with the SOON telescope used for continual observation of the sun. The SOON telescope is used at...proximity of spots refers to the angular separation between different spots that could make up a group. The area of each sunspot means the total area...degrees and the different magnetic polarities of each spot being considered. For a spot pair that has the same polarity and small angular separation

  14. Photometric measurements of solar irradiance variations due to sunspots

    International Nuclear Information System (INIS)

    Chapman, G.A.; Herzog, A.D.; Laico, D.E.; Lawrence, J.K.; Templer, M.S.

    1989-01-01

    A photometric telescope constructed to obtain photometric sunspot areas and deficits on a daily basis is described. Data from this Cartesian full disk telescope (CFDT) are analyzed with attention given to the period between June 4 and June 17, 1985 because of the availability of overlapping sunspot area and irradiance deficit data from high-resolution digital spectroheliograms made with the San Fernando Observatory 28 cm vacuum solar telescope and spectroheliograph. The CFDT sunspot deficits suggest a substantial irradiance contribution from faculae and active region plage. 23 refs

  15. Association of Plages with Sunspots: A Multi-Wavelength Study Using Kodaikanal Ca ii K and Greenwich Sunspot Area Data

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Sudip; Chatterjee, Subhamoy; Banerjee, Dipankar, E-mail: sudip@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India)

    2017-02-01

    Plages are the magnetically active chromospheric structures prominently visible in the Ca ii K line (3933.67 Å). A plage may or may not be associated with a sunspot, which is a magnetic structure visible in the solar photosphere. In this study we explore this aspect of association of plages with sunspots using the newly digitized Kodaikanal Ca ii K plage data and the Greenwich sunspot area data. Instead of using the plage index or fractional plage area and its comparison with the sunspot number, we use, to our knowledge for the first time, the individual plage areas and compare them with the sunspot area time series. Our analysis shows that these two structures, formed in two different layers, are highly correlated with each other on a timescale comparable to the solar cycle. The area and the latitudinal distributions of plages are also similar to those of sunspots. Different area thresholdings on the “butterfly diagram” reveal that plages of area ≥4 arcmin{sup 2} are mostly associated with a sunspot in the photosphere. Apart from this, we found that the cyclic properties change when plages of different sizes are considered separately. These results may help us to better understand the generation and evolution of the magnetic structures in different layers of the solar atmosphere.

  16. Sunspot Light Walls Suppressed by Nearby Brightenings

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shuhong; Zhang, Jun; Hou, Yijun; Li, Xiaohong [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robertus [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Yan, Limei, E-mail: shuhongyang@nao.cas.cn [Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)

    2017-07-01

    Light walls, as ensembles of oscillating bright structures rooted in sunspot light bridges, have not been well studied, although they are important for understanding sunspot properties. Using the Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations, here we study the evolution of two oscillating light walls each within its own active region (AR). The emission of each light wall decays greatly after the appearance of adjacent brightenings. For the first light wall, rooted within AR 12565, the average height, amplitude, and oscillation period significantly decrease from 3.5 Mm, 1.7 Mm, and 8.5 minutes to 1.6 Mm, 0.4 Mm, and 3.0 minutes, respectively. For the second light wall, rooted within AR 12597, the mean height, amplitude, and oscillation period of the light wall decrease from 2.1 Mm, 0.5 Mm, and 3.0 minutes to 1.5 Mm, 0.2 Mm, and 2.1 minutes, respectively. Particularly, a part of the second light wall even becomes invisible after the influence of a nearby brightening. These results reveal that the light walls are suppressed by nearby brightenings. Considering the complex magnetic topology in light bridges, we conjecture that the fading of light walls may be caused by a drop in the magnetic pressure, where the flux is canceled by magnetic reconnection at the site of the nearby brightening. Another hypothesis is that the wall fading is due to the suppression of driver source ( p -mode oscillation), resulting from the nearby avalanche of downward particles along reconnected brightening loops.

  17. The Sunspot Number and beyond : reconstructing detailed solar information over centuries

    Science.gov (United States)

    Lefevre, L.

    2014-12-01

    With four centuries of solar evolution, the International Sunspot Number (SSN) forms the longest solar time series currently available. It provides an essential reference for understanding and quantifying how the solar output has varied over decades and centuries and thus for assessing the variations of the main natural forcing on the Earth climate. Because of its importance, this unique time-series must be closely monitored for any possible biases and drifts. Here, we report about recent disagreements between solar indices, for example the sunspot sumber and the 10.7cm radio flux. Recent analyses indicate that while part of this divergence may be due to a calibration drift in the SSN, it also results from an intrinsic change in the global magnetic parameters of sunspots and solar active regions, suggesting a possible transition to a new activity regime. Going beyond the SSN series, in the framework of the TOSCA (www.cost-tosca.eu/) and SOLID (projects.pmodwrc.ch/solid/) projects, we produced a survey of all existing catalogs providing detailed sunspot information (Lefevre & Clette, 2014:10.1007/s11207-012-0184-5) and we also located different primary solar images and drawing collections that can be exploitable to complement the existing catalogs. These are first steps towards the construction of a multi-parametric time series of multiple sunspot and sunspot group properties over more than a century, allowing to reconstruct and extend the current 1-D SSN series. By bringing new spatial, morphological and evolutionary information, such a data set should bring major advances for the modeling of the solar dynamo and solar irradiance. We will present here the current status of this work. The preliminary version catalog now extends over the last 150 years. It makes use of data from DPD (http://fenyi.solarobs.unideb.hu/DPD/index.html), from the Uccle Solar Equatorial Table (USET:http://sidc.oma.be/uset/) operated by the Royal Obeservatory of Belgium, the Greenwich

  18. Sunspots Resource--From Ancient Cultures to Modern Research

    Science.gov (United States)

    Craig, N.

    2000-10-01

    Sunspots is a web-based lesson that was developed by the Science Education Gateway (SEGway) program with participants from the Exploratorium, a well known science Museum in San Francisco, UC Berkeley Space Sciences Laboratory, and teachers from several California schools. This space science resource allows 8-12 grade students to explore the nature of sunspots and the history of solar physics in its effort to understand their nature. Interviews with solar physicists and archeo-astronomers, historic images, cutting-edge NASA images, movies, and research results, as well as a student-centered sunspot research activity using NASA space science data defines this lesson. The sunspot resource is aligned with the NCTM and National Science Education Standards. It emphasizes inquiry-based methods and mathematical exercises through measurement, graphic data representation, analysis of NASA data, lastly, interpreting results and drawing conclusions. These resources have been successfully classroom tested in 4 middle schools in the San Francisco Unified School District as part of the 3-week Summer School Science curricula. Lessons learned from the Summer School 1999 will be explained. This resource includes teacher-friendly lesson plans, space science background material and student worksheets. There will be Sunspots lesson CD-ROM and printed version of the relevant classroom-ready materials and a teacher resource booklet available. Sunspot resource is brought to you by, The Science Education Gateway - SEGway - Project, and the HESSI satellite and NASA's Office of Space Science Sun-Earth Connection Education Forum.

  19. Latitudinal migration of sunspots based on the ESAI database

    Science.gov (United States)

    Zhang, Juan; Li, Fu-Yu; Feng, Wen

    2018-01-01

    The latitudinal migration of sunspots toward the equator, which implies there is propagation of the toroidal magnetic flux wave at the base of the solar convection zone, is one of the crucial observational bases for the solar dynamo to generate a magnetic field by shearing of the pre-existing poloidal magnetic field through differential rotation. The Extended time series of Solar Activity Indices (ESAI) elongated the Greenwich observation record of sunspots by several decades in the past. In this study, ESAI’s yearly mean latitude of sunspots in the northern and southern hemispheres during the years 1854 to 1985 is utilized to statistically test whether hemispherical latitudinal migration of sunspots in a solar cycle is linear or nonlinear. It is found that a quadratic function is statistically significantly better at describing hemispherical latitudinal migration of sunspots in a solar cycle than a linear function. In addition, the latitude migration velocity of sunspots in a solar cycle decreases as the cycle progresses, providing a particular constraint for solar dynamo models. Indeed, the butterfly wing pattern with a faster latitudinal migration rate should present stronger solar activity with a shorter cycle period, and it is located at higher latitudinal position, giving evidence to support the Babcock-Leighton dynamo mechanism.

  20. INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

    2012-10-20

    Solar acoustic waves are scattered by a sunspot due to the interaction between the acoustic waves and the sunspot. The sunspot, excited by the incident wave, generates the scattered wave. The scattered wave is added to the incident wave to form the total wave around the sunspot. The interference fringes between the scattered wave and the incident wave are visible in the intensity of the total wave because the coherent time of the incident wave is of the order of a wave period. The strength of the interference fringes anti-correlates with the width of temporal spectra of the incident wave. The separation between neighboring fringes increases with the incident wavelength and the sunspot size. The strength of the fringes increases with the radial order n of the incident wave from n = 0 to n = 2, and then decreases from n = 2 to n = 5. The interference fringes play a role analogous to holograms in optics. This study suggests the feasibility of using the interference fringes to reconstruct the scattered wavefields of the sunspot, although the quality of the reconstructed wavefields is sensitive to the noise and errors in the interference fringes.

  1. Interactions between nested sunspots. 1: The formation and breakup of a delta-type sunspot

    Science.gov (United States)

    Gaizauskas, V.; Harvey, K. L.; Proulx, M.

    1994-01-01

    We investigate a nest of sunspots in which three ordinary bipolar pairs of sunspots are aligned collinearly. The usual spreading action of the growing regions brings two spots of leading polarity together (p-p collision) and forces the leading and trailing spots of the two interior regions to overlap inot a single penumbra (p-f collision), thus forming a delta-spot. We examine digitally processed images from the Ottawa River Solar Observatory of two related events inside the delta-spot 5 days after the p-f collision begins: the violent disruption of the f-umbra, and the formation in less than a day of an hydrogen-alpha filament. The evolutionary changes in shape, area, relative motions, and brightness that we measure for each spot in the elongated nest are more compatible with Parker's (1979a) hypothesis of a sunspot as a cluster of flux tubes held together by downdrafts than with the notion of a sunspot as a monolithic plug of magnetic flux. From chromospheric developments over the delta-spot, we show that a shearing motion along a polarity inversion is more effective than convergence for creating a chromospheric filament. We invoke the release of an instability, triggered by a sequence of processes lasting 1 day or more, to explain the disruption of the f-umbra in this delta-spot. We show that the sequence is initiated when the colliding p-f umbrae reach a critical separation around 3200 +/- 200 km. We present a descriptive model in which the reconnected magnetic fields block vertical transport of convective heat flux just beneath the photosphere. We observe the formation of an unusual type of penumbra adjacent to the f-polarity portion of this delta-spot just before its disruption. A tangential penumbral band grows out of disordered matter connected to the f-umbra. We present this as evidence for the extrusion of umbral magnetic flux by thermal plumes rising through a loosely bound umbra.

  2. SEISMIC DISCRIMINATION OF THERMAL AND MAGNETIC ANOMALIES IN SUNSPOT UMBRAE

    International Nuclear Information System (INIS)

    Lindsey, C.; Cally, P. S.; Rempel, M.

    2010-01-01

    Efforts to model sunspots based on helioseismic signatures need to discriminate between the effects of (1) a strong magnetic field that introduces time-irreversible, vantage-dependent phase shifts, apparently connected to fast- and slow-mode coupling and wave absorption and (2) a thermal anomaly that includes cool gas extending an indefinite depth beneath the photosphere. Helioseismic observations of sunspots show travel times considerably reduced with respect to equivalent quiet-Sun signatures. Simulations by Moradi and Cally of waves skipping across sunspots with photospheric magnetic fields of order 3 kG show travel times that respond strongly to the magnetic field and relatively weakly to the thermal anomaly by itself. We note that waves propagating vertically in a vertical magnetic field are relatively insensitive to the magnetic field, while remaining highly responsive to the attendant thermal anomaly. Travel-time measurements for waves with large skip distances into the centers of axially symmetric sunspots are therefore a crucial resource for discrimination of the thermal anomaly beneath sunspot umbrae from the magnetic anomaly. One-dimensional models of sunspot umbrae based on compressible-radiative-magnetic-convective simulations such as by Rempel et al. can be fashioned to fit observed helioseismic travel-time spectra in the centers of sunspot umbrae. These models are based on cooling of the upper 2-4 Mm of the umbral subphotosphere with no significant anomaly beneath 4.5 Mm. The travel-time reductions characteristic of these models are primarily a consequence of a Wilson depression resulting from a strong downward buoyancy of the cooled umbral medium.

  3. Umbral oscillations as a probe of sunspot

    International Nuclear Information System (INIS)

    Abdelatif, T.E.H.

    1985-01-01

    The interaction of the solar five-minute oscillations with a sunspot is thoroughly explored, both on observational and theoretical grounds. Simple theoretical models are developed in order to understand the observations of umbral oscillations. Observations made at the National Solar Observatory detected both the three-minute and five-minute umbral oscillations at photospheric heights. The three-minute oscillations were found to have a kinetic energy density six times higher in the photosphere than in the chromosphere and to be concentrated in the central part of the umbra, supporting the photospheric resonance theory for the three-minute umbral oscillations. The five-minute oscillations are attenuated in the umbra, which appears to act as a filter in selecting some of the peaks in the power spectrum of five-minute oscillations in the surrounding photosphere. The k-omega power spectrum of the umbral oscillations shows a shift of power to longer wavelengths. Theoretical models of the transmission of acoustic waves into a magnetic region explain both observed effects

  4. Observational Evidence of a Flux Rope within a Sunspot Umbra

    Energy Technology Data Exchange (ETDEWEB)

    Guglielmino, Salvo L.; Zuccarello, Francesca [Dipartimento di Fisica e Astronomia—Sezione Astrofisica, Università di Catania, Via S. Sofia 78, I-95125 Catania (Italy); Romano, Paolo, E-mail: salvo.guglielmino@oact.inaf.it [INAF—Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95125 Catania (Italy)

    2017-09-10

    We observed an elongated filamentary bright structure inside the umbra of the big sunspot in active region NOAA 12529, which differs from the light bridges usually observed in sunspots for its morphology, magnetic configuration, and velocity field. We used observations taken with the Solar Dynamic Observatory satellite to characterize this feature. Its lifetime is 5 days, during which it reaches a maximum length of about 30″. In the maps of the vertical component of the photospheric magnetic field, a portion of the feature has a polarity opposite to that of the hosting sunspot. At the same time, in the entire feature the horizontal component of the magnetic field is about 2000 G, substantially stronger than in the surrounding penumbral filaments. Doppler velocity maps reveal the presence of both upward and downward plasma motions along the structure at the photospheric level. Moreover, looking at the chromospheric level, we noted that it is located in a region corresponding to the edge of a small filament that seems rooted in the sunspot umbra. Therefore, we interpreted the bright structure as the photospheric counterpart of a flux rope touching the sunspot and giving rise to penumbral-like filaments in the umbra.

  5. Is sunspot activity a factor in influenza pandemics?

    Science.gov (United States)

    Qu, Jiangwen

    2016-09-01

    The 2009 AH1N1 pandemic became a global health concern, although fortunately, its worst anticipated effects were not realised. While the origins of such outbreaks remain poorly understood, it is very important to identify the precipitating factors in their emergence so that future pandemics can be detected as quickly as possible. Methords: Descriptive epidemiology was used to analyse the association between influenza pandemics and possible pandemics and relative number of sunspots. Non-conditional logistic regression was performed to analyse the statistical association between sunspot extremes and influenza pandemics to within plus or minus 1 year. Almost all recorded influenza/possible pandemics have occurred in time frames corresponding to sunspot extremes, or +/- 1 year within such extremes. These periods were identified as important risk factors in both possible and confirmed influenza pandemics (odds ratio: 3.87; 95% confidence interval: 1.08 to 13.85). Extremes of sunspot activity to within plus or minus 1 year may precipitate influenza pandemics. Mechanisms of epidemic initiation and early spread are discussed including primary causation by externally derived viral variants (from space via cometary dust). Efforts to construct a comprehensive early warning system for potential influenza and other viral pandemics that include analysis of sunspot activity and stratospheric sampling for viral variants should be supported. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Long-term periodicities in the sunspot record

    International Nuclear Information System (INIS)

    Wilson, R.M.

    1984-07-01

    Sunspot records are systematically maintained, with the knowledge that an 11 year average period exists since about 1850. Thus, the sunspot record of highest quality and considered to be the most reliable is that of cycle eight through the present. On the basis of cycles 8 through 20, various combinations of sine curves were used to approximate the observed R sub MAX values (where R sub MAX is the smoothed sunspot number at cycle maximum). It is found that a three component sinusoidal function, having an 11 cycle and a 2 cycle variation on a 90 cycle periodicity, yields computed R sub MAX values which fit, reasonably well, observed R sub MAX values for the modern sunspot cycles. Extrapolation of the empirical functions forward in time allows for the projection of values of R sub MAX for cycles 21 and 22. For cycle 21, the function projects a value of 157.3, very close to the actually observed value of 164.5. For cycle 22, the function projects a value of about 107. Linear regressions applied to cycle 22 indicate a long-period cycle (cycle duration 132 months). An extensive bibliography on techniques used to estimate the time dependent behavior of sunspot cycles is provided

  7. Sunspot Oscillations From The Chromosphere To The Corona

    Science.gov (United States)

    Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.

    The behavior of the 3 minute sunspot oscillations is studied as a function of temper- ature through the transition region using observations with CDS/SOHO and TRACE. The oscillations occur above the umbra, with amplitudes increasing to a maximum near 200 000 K, then decreasing towards higher temperatures. Deviations from pure linear oscillations are present in several cases. Power spectra of the oscillations are remarkably similar in the chromosphere and through the transition region in contra- diction to the predictions of the sunspot filter theory. The 3 minute oscillations pene- trate to the low temperature end of the corona, where they are channeled into smaller areas coinciding with the endpoints of sunspot coronal loops. This differs from the transition zone where the oscillating region covers the umbra.

  8. Long-term Modulation of Cosmic Ray Intensity in relation to Sunspot ...

    Indian Academy of Sciences (India)

    it should be more closely connected with cosmic ray modulation than with other solar characteristics (sunspot numbers or coronal emission intensity). The intensity of galactic cosmic rays varies inversely with sunspot numbers, having their maximum intensity at the minimum of the 11-year sunspot cycle (Forbush 1954, 1958) ...

  9. The magnetic nature of umbra-penumbra boundary in sunspots

    Science.gov (United States)

    Jurčák, J.; Rezaei, R.; González, N. Bello; Schlichenmaier, R.; Vomlel, J.

    2018-03-01

    Context. Sunspots are the longest-known manifestation of solar activity, and their magnetic nature has been known for more than a century. Despite this, the boundary between umbrae and penumbrae, the two fundamental sunspot regions, has hitherto been solely defined by an intensity threshold. Aim. Here, we aim at studying the magnetic nature of umbra-penumbra boundaries in sunspots of different sizes, morphologies, evolutionary stages, and phases of the solar cycle. Methods: We used a sample of 88 scans of the Hinode/SOT spectropolarimeter to infer the magnetic field properties in at the umbral boundaries. We defined these umbra-penumbra boundaries by an intensity threshold and performed a statistical analysis of the magnetic field properties on these boundaries. Results: We statistically prove that the umbra-penumbra boundary in stable sunspots is characterised by an invariant value of the vertical magnetic field component: the vertical component of the magnetic field strength does not depend on the umbra size, its morphology, and phase of the solar cycle. With the statistical Bayesian inference, we find that the strength of the vertical magnetic field component is, with a likelihood of 99%, in the range of 1849-1885 G with the most probable value of 1867 G. In contrast, the magnetic field strength and inclination averaged along individual boundaries are found to be dependent on the umbral size: the larger the umbra, the stronger and more horizontal the magnetic field at its boundary. Conclusions: The umbra and penumbra of sunspots are separated by a boundary that has hitherto been defined by an intensity threshold. We now unveil the empirical law of the magnetic nature of the umbra-penumbra boundary in stable sunspots: it is an invariant vertical component of the magnetic field.

  10. A new look at sunspot formation using theory and observations

    Science.gov (United States)

    Losada, I. R.; Warnecke, J.; Glogowski, K.; Roth, M.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.

    2017-10-01

    Sunspots are of basic interest in the study of the Sun. Their relevance ranges from them being an activity indicator of magnetic fields to being the place where coronal mass ejections and flares erupt. They are therefore also an important ingredient of space weather. Their formation, however, is still an unresolved problem in solar physics. Observations utilize just 2D surface information near the spot, but it is debatable how to infer deep structures and properties from local helioseismology. For a long time, it was believed that flux tubes rising from the bottom of the convection zone are the origin of the bipolar sunspot structure seen on the solar surface. However, this theory has been challenged, in particular recently by new surface observation, helioseismic inversions, and numerical models of convective dynamos. In this article we discuss another theoretical approach to the formation of sunspots: the negative effective magnetic pressure instability. This is a large-scale instability, in which the total (kinetic plus magnetic) turbulent pressure can be suppressed in the presence of a weak large-scale magnetic field, leading to a converging downflow, which eventually concentrates the magnetic field within it. Numerical simulations of forced stratified turbulence have been able to produce strong super-equipartition flux concentrations, similar to sunspots at the solar surface. In this framework, sunspots would only form close to the surface due to the instability constraints on stratification and rotation. Additionally, we present some ideas from local helioseismology, where we plan to use the Hankel analysis to study the pre-emergence phase of a sunspot and to constrain its deep structure and formation mechanism.

  11. SOHO sees right through the Sun, and finds sunspots on the far side

    Science.gov (United States)

    2000-03-01

    The story is told today in the journal Science by Charles Lindsey of Tucson, Arizona, and Doug Braun of Boulder, Colorado. They realised that the analytical witchcraft called helioseismic holography might open a window right through the Sun. And the technique worked when they used it to decode waves seen on the visible surface by one of SOHO's instruments, the Michelson Doppler Imager, or MDI. "We've known for ten years that in theory we could make the Sun transparent all the way to the far side," said Charles Lindsey. "But we needed observations of exceptional quality. In the end we got them, from MDI on SOHO." For more than 100 years scientists have been aware that groups of dark sunspots on the Sun's visible face are often the scene of flares and other eruptions. Nowadays they watch the Sun more closely than ever, because modern systems are much more vulnerable to solar disturbances than old-style technology was. The experts can still be taken by surprise, because the Sun turns on its axis. A large group of previously hidden sunspots can suddenly swing into view on the eastern (left-hand) edge of the Sun. It may already be blazing away with menacing eruptions. With a far-side preview of sunspots, nasty shocks for the space weather forecasters may now be avoidable. Last year, French and Finnish scientists used SWAN, another instrument on SOHO, to detect activity on the far side. They saw an ultraviolet glow lighting up gas in the Solar System beyond the Sun, and moving across the sky like a lighthouse beam as the Sun rotated. The method used by Lindsey and Braun with MDI data is completely different, and it pinpoints the source of the activity on the far side. Solar seismology chalks up another success Detection of sound waves reverberating through the Sun opened its gassy interior for investigation, in much the same way as seismologists learned to explore the Earth's rocky interior with earthquake waves. Using special telescopes on the ground and in space

  12. STOCHASTIC DESCRIPTION OF THE HIGH-FREQUENCY CONTENT OF DAILY SUNSPOTS AND EVIDENCE FOR REGIME CHANGES

    International Nuclear Information System (INIS)

    Shapoval, A.; Le Mouël, J.-L.; Courtillot, V.; Shnirman, M.

    2015-01-01

    The irregularity index λ is applied to the high-frequency content of daily sunspot numbers ISSN. This λ is a modification of the standard maximal Lyapunov exponent. It is computed here as a function of embedding dimension m, within four-year time windows centered at the maxima of Schwabe cycles. The λ(m) curves form separate clusters (pre-1923 and post-1933). This supports a regime transition and narrows its occurrence to cycle 16, preceding the growth of activity leading to the Modern Maximum. The two regimes are reproduced by a simple autoregressive process AR(1), with the mean of Poisson noise undergoing 11 yr modulation. The autocorrelation a of the process (linked to sunspot lifetime) is a ≈ 0.8 for 1850-1923 and ≈0.95 for 1933-2013. The AR(1) model suggests that groups of spots appear with a Poisson rate and disappear at a constant rate. We further applied the irregularity index to the daily sunspot group number series for the northern and southern hemispheres, provided by the Greenwich Royal Observatory (RGO), in order to study a possible desynchronization. Correlations between the north and south λ(m) curves vary quite strongly with time and indeed show desynchronization. This may reflect a slow change in the dimension of an underlying dynamical system. The ISSN and RGO series of group numbers do not imply an identical mechanism, but both uncover a regime change at a similar time. Computation of the irregularity index near the maximum of cycle 24 will help in checking whether yet another regime change is under way

  13. HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

    Energy Technology Data Exchange (ETDEWEB)

    Felipe, T. [Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife (Spain); Braun, D. C.; Crouch, A. D. [NorthWest Research Associates, Colorado Research Associates, Boulder, CO 80301 (United States); Birch, A. C., E-mail: tobias@iac.es [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2016-10-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

  14. HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

    International Nuclear Information System (INIS)

    Felipe, T.; Braun, D. C.; Crouch, A. D.; Birch, A. C.

    2016-01-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

  15. Are climatological correlations with the Hale double sunspot cycle meaningful

    International Nuclear Information System (INIS)

    Goldberg, R.A.; Herman, J.R.

    1975-09-01

    A sunspot cycle which may have been subject to a predicted phase reversal between 1800 and 1880 A.D. is discussed. Several climatological parameters normally correlated with this cycle are examined and do not exhibit a corresponding phase reversal during this period. It is proposed that this apparent discrepency can be resolved by suitable observations during the upcoming half decade

  16. Automated Sunspot Detection and Classification Using SOHO/MDI Imagery

    Science.gov (United States)

    2015-03-01

    to the geocentric North). 3. Focus and size of the solar disk is adjusted to fit an 18 cm diameter circle on the worksheet. 4. Analyst hand draws the...General Nature of the Sunspot,” The Astrophysical Journal 230, 905–913 (1979). 14. Wheatland, M. S., “A Bayesian Approach to Solar Flare Prediction,” The

  17. 3-color photometry of a sunspot using speckle masking techniques

    NARCIS (Netherlands)

    Wiehr, E.; Sütterlin, P.

    1998-01-01

    A three-colour photometry is used to deduce the temperature of sunspot fine-structures. Using the Speckle-Masking method for image restoration, the resulting images (one per colour and burst) have a spatial resolution only limited by the telescope's aperture, i.e. 95km (blue), 145 km (red) and

  18. SUNSPOT CYCLES IMPACTS ON TOURISM AND QUALITY OF LIFE

    Directory of Open Access Journals (Sweden)

    Tadeja Jere Jakulin

    2017-09-01

    Full Text Available We live under the influence of natural cycles caused by the rotation of our planet and its revolution around the sun. The nature of our nearest star is also subject to cyclical change. This article presents a study of a correlation between sunspot cycles and foreign tourists arrivals in Slovenia, based on historical data between sunspot cycles and sea salt production in Slovenia's Municipality of Piran during the Maunder Minimum period (1645-1715. The production of salt by the solar evaporation of brine in salt pans and tourist industry are seasonal economic activities that are affected by changes to the weather. The paper looks at sea salt production in Piran during a particular period in the past. The repetition of the sea salt production in the past is not possible. For this reason, the study uses mathematical tools and an additional case study, which analyses arrivals of foreign tourists to Slovenia over the past 65 years (1948-2012. The study has two purposes: to identify a linear correlation coefficient, which provides evidence of a correlation between arrivals of foreign tourists to Slovenia and sunspot cycles and to develop a causal loop diagram (CLD or so called qualitative model of a complex tourism system, which shows the interdependency of sunspot cycles, tourism system, and quality of life.

  19. Application of Avco data analysis and prediction techniques (ADAPT) to prediction of sunspot activity

    Science.gov (United States)

    Hunter, H. E.; Amato, R. A.

    1972-01-01

    The results are presented of the application of Avco Data Analysis and Prediction Techniques (ADAPT) to derivation of new algorithms for the prediction of future sunspot activity. The ADAPT derived algorithms show a factor of 2 to 3 reduction in the expected 2-sigma errors in the estimates of the 81-day running average of the Zurich sunspot numbers. The report presents: (1) the best estimates for sunspot cycles 20 and 21, (2) a comparison of the ADAPT performance with conventional techniques, and (3) specific approaches to further reduction in the errors of estimated sunspot activity and to recovery of earlier sunspot historical data. The ADAPT programs are used both to derive regression algorithm for prediction of the entire 11-year sunspot cycle from the preceding two cycles and to derive extrapolation algorithms for extrapolating a given sunspot cycle based on any available portion of the cycle.

  20. TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

    International Nuclear Information System (INIS)

    McClintock, B. H.; Norton, A. A.

    2016-01-01

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations

  1. Improvement of the photometric sunspot index and changes of the disk-integrated sunspot contrast with time

    Science.gov (United States)

    Froehlich, Claus; Pap, Judit M.; Hudson, Hugh S.

    1994-06-01

    The photometric sunspot index (PSI) was developed to study the effects of sunspots on solar irradiance. It is calculated from the sunspot data published in the Solar-Geophysical Data catalog. It has been shown that the former PSI models overestimate the effect of dark sunspots on solar irradiance; furthermore results of direct sunspot photometry indicate that the contrast of spots depends on their area. An improved PSI calculation is presented; it takes into account the area dependence of the contrast and calculates `true' daily means for each observation using the differential rotation of the spots. Moreover, the observations are screened for outliers which improves the homogeneity of the data set substantially, at least for the period after December 1981 when NOAA started to report data from a few instead of one to two stations. A detailed description of the method is provided. The correlation between the newly calculated PSI and total solar irradiance is studied for different phases of the solar cycles 21 and 22 using bi-variate spectral analysis. The results can be used as a `calibration' of PSI in terms of gain, the factor by which PSI has to be multiplied to yield the observed irradiance change. The factor changes with time from about 0.6 in 1980 to 1.1 in 1990. This unexpected result cannot be interpreted by a change of the contrast relative to the quiet Sun (as it is normally defined and determined by direct photometry) but rather as a change of the contrast between the spots and their surrounding as seen in total irradiance (integrated over the solar disk). This may partly be explained by a change in the ratio between the areas of the spots and the surrounding faculae.

  2. Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2005-03-01

    Full Text Available Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma

  3. Molecular Diagnostics of the Internal Structure of Starspots and Sunspots

    Science.gov (United States)

    Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.; Lagg, A.; Petit, P.; Arnaud, J.

    2006-12-01

    We have analyzed the usefulness of molecules as a diagnostic tool for studying solar and stellar magnetism with the molecular Zeeman and Paschen-Back effects. In the first part we concentrate on molecules that are observed in sunspots such as MgH and TiO. We present calculated molecular line profiles obtained by assuming magnetic fields of 2-3 kG and compare these synthetic Stokes profiles with spectro-polarimetric observations in sunspots. The good agreement between the theory and observations allows us to turn our attention in the second part to starspots to gain insight into their internal structure. We investigate the temperature range in which the selected molecules can serve as indicators for magnetic fields on highly active cool stars and compare synthetic Stokes profiles with our recent observations.

  4. Aurorae, sunspots and weather, mainly since A.D. 1200

    International Nuclear Information System (INIS)

    Schove, D.J.

    1981-01-01

    Auroral records recieved for the Spectrum of Time project were used in 1955 to estimate sunspot activity and the dates maxima and minima back to 649 B.C. An additional set of rules has been developed and has made possible further improvements utilizing the separate auroral maxima associated with flares and coronal holes on the sun. A further set can now be given. 1) The time between sunspot maxima depends especially on the ratio of the amplitudes: the time between minima is high if the next cycle is very weak and low when the two consecutive cycles are both strong. 2) The time of rise is usually dependent on the strength of the next maxima, and the time of fall is low when a moderate cycle is followed by a strong one. (orig./WL)

  5. LONG-TERM MEASUREMENTS OF SUNSPOT MAGNETIC TILT ANGLES

    Energy Technology Data Exchange (ETDEWEB)

    Li Jing [Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States); Ulrich, Roger K., E-mail: jli@igpp.ucla.edu [Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095-1567 (United States)

    2012-10-20

    Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing latitude (Joy's law) at a rate of {approx}0.{sup 0}5 per degree of latitude. Tilt angles of spots appear largely invariant with respect to time at a given latitude, but they decrease by {approx}0.{sup 0}9 per year on average, a trend that largely reflects Joy's law following the butterfly diagram. We find an asymmetry between the hemispheres in the mean tilt angles. On average, the tilts are greater in the Southern than in the Northern Hemisphere for all latitude zones, and the differences increase with increasing latitude.

  6. Visual Circular Analysis of 266 Years of Sunspot Counts.

    Science.gov (United States)

    Buelens, Bart

    2016-06-01

    Sunspots, colder areas that are visible as dark spots on the surface of the Sun, have been observed for centuries. Their number varies with a period of ∼11 years, a phenomenon closely related to the solar activity cycle. Recently, observation records dating back to 1749 have been reassessed, resulting in the release of a time series of sunspot numbers covering 266 years of observations. This series is analyzed using circular analysis to determine the periodicity of the occurrence of solar maxima. The circular analysis is combined with spiral graphs to provide a single visualization, simultaneously showing the periodicity of the series, the degree to which individual cycle lengths deviate from the average period, and differences in levels reached during the different maxima. This type of visualization of cyclic time series with varying cycle lengths in which significant events occur periodically is broadly applicable. It is aimed particularly at science communication, education, and public outreach.

  7. The Temperature - Magnetic Field Relation in Observed and Simulated Sunspots

    Czech Academy of Sciences Publication Activity Database

    Sobotka, Michal; Rezaei, R.

    2017-01-01

    Roč. 292, č. 12 (2017), 188/1-188/12 ISSN 0038-0938 R&D Projects: GA ČR(CZ) GA14-04338S; GA MŠk(CZ) 7E13003 EU Projects: European Commission(XE) 312495 - SOLARNET Institutional support: RVO:67985815 Keywords : sunspots * magnetic fields * comparison Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 2.682, year: 2016

  8. SPECTROPOLARIMETRICALLY ACCURATE MAGNETOHYDROSTATIC SUNSPOT MODEL FOR FORWARD MODELING IN HELIOSEISMOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Przybylski, D.; Shelyag, S.; Cally, P. S. [Monash Center for Astrophysics, School of Mathematical Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2015-07-01

    We present a technique to construct a spectropolarimetrically accurate magnetohydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the constructed model we perform a simulation of acoustic wave propagation, conversion, and absorption in the solar interior and photosphere with the sunspot embedded into it. With the 6173 Å magnetically sensitive photospheric absorption line of neutral iron, we calculate observable quantities such as continuum intensities, Doppler velocities, as well as the full Stokes vector for the simulation at various positions at the solar disk, and analyze the influence of non-locality of radiative transport in the solar photosphere on helioseismic measurements. Bisector shapes were used to perform multi-height observations. The differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterized. An increase in acoustic power in the simulated observations of the sunspot umbra away from the solar disk center was confirmed as the slow magnetoacoustic wave.

  9. SPECTROPOLARIMETRICALLY ACCURATE MAGNETOHYDROSTATIC SUNSPOT MODEL FOR FORWARD MODELING IN HELIOSEISMOLOGY

    International Nuclear Information System (INIS)

    Przybylski, D.; Shelyag, S.; Cally, P. S.

    2015-01-01

    We present a technique to construct a spectropolarimetrically accurate magnetohydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the constructed model we perform a simulation of acoustic wave propagation, conversion, and absorption in the solar interior and photosphere with the sunspot embedded into it. With the 6173 Å magnetically sensitive photospheric absorption line of neutral iron, we calculate observable quantities such as continuum intensities, Doppler velocities, as well as the full Stokes vector for the simulation at various positions at the solar disk, and analyze the influence of non-locality of radiative transport in the solar photosphere on helioseismic measurements. Bisector shapes were used to perform multi-height observations. The differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterized. An increase in acoustic power in the simulated observations of the sunspot umbra away from the solar disk center was confirmed as the slow magnetoacoustic wave

  10. Photospheric Origin of Three-minute Oscillations in a Sunspot

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Jongchul; Lee, Jeongwoo; Cho, Kyuhyoun; Song, Donguk [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Cho, Kyungsuk; Yurchyshyn, Vasyl [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)

    2017-02-10

    The origin of the three-minute oscillations of intensity and velocity observed in the chromosphere of sunspot umbrae is still unclear. We investigated the spatio-spectral properties of the 3 minute oscillations of velocity in the photosphere of a sunspot umbra as well as those in the low chromosphere using the spectral data of the Ni i λ 5436, Fe i λ 5435, and Na i D{sub 2} λ 5890 lines taken by the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. As a result, we found a local enhancement of the 3 minute oscillation power in the vicinities of a light bridge (LB) and numerous umbral dots (UDs) in the photosphere. These 3 minute oscillations occurred independently of the 5 minute oscillations. Through wavelet analysis, we determined the amplitudes and phases of the 3 minute oscillations at the formation heights of the spectral lines, and they were found to be consistent with the upwardly propagating slow magnetoacoustic waves in the photosphere with energy flux large enough to explain the chromospheric oscillations. Our results suggest that the 3 minute chromospheric oscillations in this sunspot may have been generated by magnetoconvection occurring in the LB and UDs.

  11. Frequently Occurring Reconnection Jets from Sunspot Light Bridges

    Science.gov (United States)

    Tian, Hui; Yurchyshyn, Vasyl; Peter, Hardi; Solanki, Sami K.; Young, Peter R.; Ni, Lei; Cao, Wenda; Ji, Kaifan; Zhu, Yingjie; Zhang, Jingwen; Samanta, Tanmoy; Song, Yongliang; He, Jiansen; Wang, Linghua; Chen, Yajie

    2018-02-01

    Solid evidence of magnetic reconnection is rarely reported within sunspots, the darkest regions with the strongest magnetic fields and lowest temperatures in the solar atmosphere. Using the world’s largest solar telescope, the 1.6 m Goode Solar Telescope, we detect prevalent reconnection through frequently occurring fine-scale jets in the Hα line wings at light bridges, the bright lanes that may divide the dark sunspot core into multiple parts. Many jets have an inverted Y-shape, shown by models to be typical of reconnection in a unipolar field environment. Simultaneous spectral imaging data from the Interface Region Imaging Spectrograph show that the reconnection drives bidirectional flows up to 200 km s‑1, and that the weakly ionized plasma is heated by at least an order of magnitude up to ∼80,000 K. Such highly dynamic reconnection jets and efficient heating should be properly accounted for in future modeling efforts of sunspots. Our observations also reveal that the surge-like activity previously reported above light bridges in some chromospheric passbands such as the Hα core has two components: the ever-present short surges likely to be related to the upward leakage of magnetoacoustic waves from the photosphere, and the occasionally occurring long and fast surges that are obviously caused by the intermittent reconnection jets.

  12. MODELING THE CHROMOSPHERE OF A SUNSPOT AND THE QUIET SUN

    Energy Technology Data Exchange (ETDEWEB)

    Avrett, E.; Tian, H. [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States); Landi, E. [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Curdt, W. [Max Planck Institut für Sonnensystemfoschung, Goettingen (Germany); Wülser, J.-P. [Lockheed Martin Advanced Techonology Center (United States)

    2015-10-01

    Semiempirical atmospheric modeling attempts to match an observed spectrum by finding the temperature distribution and other physical parameters along the line of sight through the emitting region such that the calculated spectrum agrees with the observed one. In this paper we take the observed spectrum of a sunspot and the quiet Sun in the EUV wavelength range 668–1475 Å from the 2001 SUMER atlas of Curdt et al. to determine models of the two atmospheric regions, extending from the photosphere through the overlying chromosphere into the transition region. We solve the coupled statistical equilibrium and optically thick radiative transfer equations for a set of 32 atoms and ions. The atoms that are part of molecules are treated separately, and are excluded from the atomic abundances and atomic opacities. We compare the Mg ii k line profile observations from the Interface Region Imaging Spectrograph with the profiles calculated from the two models. The calculated profiles for the sunspot are substantially lower than the observed ones, based on the SUMER models. The only way we have found to raise the calculated Mg ii lines to agree with the observations is to introduce illumination of the sunspot from the surrounding active region.

  13. Prediction on sunspot activity based on fuzzy information granulation and support vector machine

    Science.gov (United States)

    Peng, Lingling; Yan, Haisheng; Yang, Zhigang

    2018-04-01

    In order to analyze the range of sunspots, a combined prediction method of forecasting the fluctuation range of sunspots based on fuzzy information granulation (FIG) and support vector machine (SVM) was put forward. Firstly, employing the FIG to granulate sample data and extract va)alid information of each window, namely the minimum value, the general average value and the maximum value of each window. Secondly, forecasting model is built respectively with SVM and then cross method is used to optimize these parameters. Finally, the fluctuation range of sunspots is forecasted with the optimized SVM model. Case study demonstrates that the model have high accuracy and can effectively predict the fluctuation of sunspots.

  14. A Standard Law for the Equatorward Drift of the Sunspot Zones

    Science.gov (United States)

    Hathaway, David H.

    2012-01-01

    The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2012. When these centroid positions are plotted and analyzed as functions of time from each sunspot cycle maximum there appears to be systematic differences in the positions and equatorward drift rates as a function of sunspot cycle amplitude. If, instead, these centroid positions are plotted and analyzed as functions of time from each sunspot cycle minimum then most of the differences in the positions and equatorward drift rates disappear. The differences that remain disappear entirely if curve fitting is used to determine the starting times (which vary by as much as 8 months from the times of minima). The sunspot zone latitudes and equatorward drift measured relative to this starting time follow a standard path for all cycles with no dependence upon cycle strength or hemispheric dominance. Although Cycle 23 was peculiar in its length and the strength of the polar fields it produced, it too shows no significant variation from this standard. This standard law, and the lack of variation with sunspot cycle characteristics, is consistent with Dynamo Wave mechanisms but not consistent with current Flux Transport Dynamo models for the equatorward drift of the sunspot zones.

  15. Distribution of electric currents in sunspots from photosphere to corona

    Energy Technology Data Exchange (ETDEWEB)

    Gosain, Sanjay [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Démoulin, Pascal [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); López Fuentes, Marcelo [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC. 67, Suc. 28 Buenos Aires 1428 (Argentina)

    2014-09-20

    We present a study of two regular sunspots that exhibit nearly uniform twist from the photosphere to the corona. We derive the twist parameter in the corona and in the chromosphere by minimizing the difference between the extrapolated linear force-free field model field lines and the observed intensity structures in the extreme-ultraviolet images of the Sun. The chromospheric structures appear more twisted than the coronal structures by a factor of two. Further, we derive the vertical component of electric current density, j{sub z} , using vector magnetograms from the Hinode Solar Optical Telescope (SOT). The spatial distribution of j{sub z} has a zebra pattern of strong positive and negative values owing to the penumbral fibril structure resolved by Hinode/SOT. This zebra pattern is due to the derivative of the horizontal magnetic field across the thin fibrils; therefore, it is strong and masks weaker currents that might be present, for example, as a result of the twist of the sunspot. We decompose j{sub z} into the contribution due to the derivatives along and across the direction of the horizontal field, which follows the fibril orientation closely. The map of the tangential component has more distributed currents that are coherent with the chromospheric and coronal twisted structures. Moreover, it allows us to map and identify the direct and return currents in the sunspots. Finally, this decomposition of j{sub z} is general and can be applied to any vector magnetogram in order to better identify the weaker large-scale currents that are associated with coronal twisted/sheared structures.

  16. High Velocity Horizontal Motions at the Edge of Sunspot Penumbrae

    Science.gov (United States)

    Hagenaar-Daggett, Hermance J.; Shine, R.

    2010-05-01

    The outer edges of sunspot penumbrae have long been noted as a region of interesting dynamics including formation of MMFs, extensions and retractions of the penumbral tips, fast moving (2-3 km/s) bright features dubbed"streakers", and localized regions of high speed downflows interpreted as Evershed "sinks". Using 30s cadence movies of high spatial resolution G band and Ca II H images taken by the Hinode SOT/FPP instrument from 5-7 Jan 2007, we have been investigating the penumbra around a sunspot in AR 10933. In addition to the expected phenomena, we also see occasional small dark crescent-shaped features with high horizontal velocities (6.5 km/s) in G band movies. These appear to be emitted from penumbral tips. They travel about 1.5 Mm developing a bright wake that evolves into a slower moving (1-2 km/s) bright feature. In some cases, there may be an earlier outward propagating disturbance within the penumbra. We have also analyzed available Fe 6302 Stokes V images to obtain information on the magnetic field. Although only lower resolution 6302 images made with a slower cadence are available for these particular data sets, we can establish that the features have the opposite magnetic polarity of the sunspot. This observation may be in agreement with simulations showing that a horizontal flux tube develops crests that move outward with a velocity as large as 10 km/s. This work was supported by NASA contract NNM07AA01C.

  17. Observations of the birth and fine structure of sunspot penumbrae

    International Nuclear Information System (INIS)

    Collados, M.; Garcia de la Rosa, J.I.; Moreno-Insertis, F.; Vazquez, M.

    1985-01-01

    High resolution white-light pictures of sunspot penumbrae are presented. These include pictures showing details of their filamentary structure and some instances of birth of a penumbra. The observations are discussed in the framework of current penumbra theories. A series of pictures have been presented, which give additional evidence of the existence of dark penumbral filaments as individual structures. With respect to the birth of the penumbra some new observational aspects can be seen. The existence of the filamentary penumbra even in the first moments, its non uniformity and its short length are the major aspects derived from the pictures

  18. Investigation of Quasi-periodic Solar Oscillations in Sunspots Based on SOHO/MDI Magnetograms

    Science.gov (United States)

    Kallunki, J.; Riehokainen, A.

    2012-10-01

    In this work we study quasi-periodic solar oscillations in sunspots, based on the variation of the amplitude of the magnetic field strength and the variation of the sunspot area. We investigate long-period oscillations between three minutes and ten hours. The magnetic field synoptic maps were obtained from the SOHO/MDI. Wavelet (Morlet), global wavelet spectrum (GWS) and fast Fourier transform (FFT) methods are used in the periodicity analysis at the 95 % significance level. Additionally, the quiet Sun area (QSA) signal and an instrumental effect are discussed. We find several oscillation periods in the sunspots above the 95 % significance level: 3 - 5, 10 - 23, 220 - 240, 340 and 470 minutes, and we also find common oscillation periods (10 - 23 minutes) between the sunspot area variation and that of the magnetic field strength. We discuss possible mechanisms for the obtained results, based on the existing models for sunspot oscillations.

  19. SUNSPOT AND STARSPOT LIFETIMES IN A TURBULENT EROSION MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, Yuri E. [Department of Mathematics, University of Waikato, P. B. 3105, Hamilton (New Zealand); Wheatland, M. S. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

    2017-01-10

    Quantitative models of sunspot and starspot decay predict the timescale of magnetic diffusion and may yield important constraints in stellar dynamo models. Motivated by recent measurements of starspot lifetimes, we investigate the disintegration of a magnetic flux tube by nonlinear diffusion. Previous theoretical studies are extended by considering two physically motivated functional forms for the nonlinear diffusion coefficient D : an inverse power-law dependence D ∝ B {sup −ν} and a step-function dependence of D on the magnetic field magnitude B . Analytical self-similar solutions are presented for the power-law case, including solutions exhibiting “super fast” diffusion. For the step-function case, the heat-balance integral method yields approximate solutions, valid for moderately suppressed diffusion in the spot. The accuracy of the resulting solutions is confirmed numerically, using a method which provides an accurate description of long-time evolution by imposing boundary conditions at infinite distance from the spot. The new models may allow insight into the differences and similarities between sunspots and starspots.

  20. Response of Solar Irradiance to Sunspot-area Variations

    Science.gov (United States)

    Dudok de Wit, T.; Kopp, G.; Shapiro, A.; Witzke, V.; Kretzschmar, M.

    2018-02-01

    One of the important open questions in solar irradiance studies is whether long-term variability (i.e., on timescales of years and beyond) can be reconstructed by means of models that describe short-term variability (i.e., days) using solar proxies as inputs. Preminger & Walton showed that the relationship between spectral solar irradiance and proxies of magnetic-flux emergence, such as the daily sunspot area, can be described in the framework of linear system theory by means of the impulse response. We significantly refine that empirical model by removing spurious solar-rotational effects and by including an additional term that captures long-term variations. Our results show that long-term variability cannot be reconstructed from the short-term response of the spectral irradiance, which questions the extension of solar proxy models to these timescales. In addition, we find that the solar response is nonlinear in a way that cannot be corrected simply by applying a rescaling to a sunspot area.

  1. Extreme Value Theory Applied to the Millennial Sunspot Number Series

    Science.gov (United States)

    Acero, F. J.; Gallego, M. C.; García, J. A.; Usoskin, I. G.; Vaquero, J. M.

    2018-01-01

    In this work, we use two decadal sunspot number series reconstructed from cosmogenic radionuclide data (14C in tree trunks, SN 14C, and 10Be in polar ice, SN 10Be) and the extreme value theory to study variability of solar activity during the last nine millennia. The peaks-over-threshold technique was used to compute, in particular, the shape parameter of the generalized Pareto distribution for different thresholds. Its negative value implies an upper bound of the extreme SN 10Be and SN 14C timeseries. The return level for 1000 and 10,000 years were estimated leading to values lower than the maximum observed values, expected for the 1000 year, but not for the 10,000 year return levels, for both series. A comparison of these results with those obtained using the observed sunspot numbers from telescopic observations during the last four centuries suggests that the main characteristics of solar activity have already been recorded in the telescopic period (from 1610 to nowadays) which covers the full range of solar variability from a Grand minimum to a Grand maximum.

  2. Depressed emission between magnetic arcades near a sunspot

    Science.gov (United States)

    Ryabov, B. I.; Shibasaki, K.

    The locations of the depressed emission in microwaves, EUV and soft X-rays are compared with each other and with the location of the plasma outflow in the active region (AR) 8535 on the Sun. We found that two open-field regions overlap the regions of depressed emission near the AR's sunspot. These two open-field regions are simulated with the potential-field source-surface (PFSS) model under radial distances of RSS = 1.8 R⊙ and RSS = 2.5 R⊙. Each open-field region is located between the arcades of the loops of the same magnetic polarity. The former open-field region covers the region of the plasma outflow, which is thus useful for the tests on connection to the heliosphere. The utmost microwave depression of the intensity in the ordinary mode (the Very Large Array 15 GHz observations) also overlaps the region of the plasma outflow and thus indicates this outflow. The lasting for eight days depression in soft X-rays and the SOHO EIT 2.84× 10-8 m images are attributed to the evacuation of as hot coronal plasma as T≥ 2× 106 K from the extended in height (``open") magnetic structures. We conclude that the AR 8535 presents the sunspot atmosphere affected by the large-scale magnetic fields.

  3. Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

    Directory of Open Access Journals (Sweden)

    V. Mussino

    1994-08-01

    Full Text Available Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

  4. Sunspot Equilibria in a Production Economy: Do Rational Animal Spirits Cause Overproduction?

    OpenAIRE

    Kajii, Atsushi

    2008-01-01

    We study a standard two period economy with one nominal bond and one firm. The input of the firm is done in the first period and financed with the nominal bond, and its profits are distributed to the shareholders in the second period. We show that a sunspot equilibrium exists around each efficient equilibrium. The interest rate is lower than optimal and there is over production in sunspot equilibria, under some conditions. But a sunspot equilibrium does not exist if the profit share can be tr...

  5. The photospheric vector magnetic field of a sunspot and its vertical gradient

    Science.gov (United States)

    Hagyard, M. J.; West, E. A.; Tandberg-Hanssen, E.; Smith, J. E.; Henze, W., Jr.; Beckers, J. M.; Bruner, E. C.; Hyder, C. L.; Gurman, J. B.; Shine, R. A.

    1981-01-01

    The results of direct comparisons of photospheric and transition region line-of-sight field observations of sunspots using the SMM UV spectrometer and polarimeter are reported. The analysis accompanying the data is concentrated on demonstrating that the sunspot concentrated magnetic field extends into the transition region. An observation of a sunspot on Oct. 23, 1980 at the S 18 E 03 location is used as an example. Maximum field strengths ranged from 2030-2240 gauss for large and small umbrae viewed and inclination of the field to the line-of-sight was determined for the photosphere and transition region. The distribution of the magnetic field over the sunspot and variation of the line-of-sight gradient are discussed, as are the magnitudes and gradients of the photospheric field across the penumbral-photospheric boundaries.

  6. Historical evidence concerning the Sun: interpretation of sunspot records during the telescopic and pretelescopic eras

    International Nuclear Information System (INIS)

    Stephenson, F.R.

    1990-01-01

    The value of sunspot observations in investigating solar activity trends - mainly on the centennial to millennial timescale - is considered in some detail. It is shown that although observations made since the mid-eighteenth century are in general very reliable indicators of solar activity, older data are of dubious quality and utility. The sunspot record in both the pretelescopic and early telescopic periods appears to be confused by serious data artefacts. (author)

  7. DYNAMICS IN SUNSPOT UMBRA AS SEEN IN NEW SOLAR TELESCOPE AND INTERFACE REGION IMAGING SPECTROGRAPH DATA

    Energy Technology Data Exchange (ETDEWEB)

    Yurchyshyn, V.; Abramenko, V. [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States); Kilcik, A. [Department of Space Science and Technologies, Akdeniz University, 07058 Antalya (Turkey)

    2015-01-10

    We analyze sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the difference between the shock arrival times as measured by the Mg II k 2796.35 Å and Si IV 1393.76 Å line formation levels changes during the observed period, and peak-to-peak delays may range from 40 s to zero. The intensity of chromospheric shocks also displays long-term (about 20 min) variations. NST's high spatial resolution Hα data allowed us to conclude that, in this sunspot, umbral flashes (UFs) appeared in the form of narrow bright lanes stretched along the light bridges and around clusters of umbral bright points. The time series also suggested that UFs preferred to appear on the sunspot-center side of light bridges, which may indicate the existence of a compact sub-photospheric driver of sunspot oscillations. The sunspot's umbra as seen in the IRIS chromospheric and transition region data appears bright above the locations of light bridges and the areas where the dark umbra is dotted with clusters of umbral dots. Co-spatial and co-temporal data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory showed that the same locations were associated with bright footpoints of coronal loops suggesting that the light bridges may play an important role in heating the coronal sunspot loops. Finally, the power spectra analysis showed that the intensity of chromospheric and transition region oscillations significantly vary across the umbra and with height, suggesting that umbral non-uniformities and the structure of sunspot magnetic fields may play a role in wave propagation and heating of umbral loops.

  8. SUNSPOT ROTATION AS A DRIVER OF MAJOR SOLAR ERUPTIONS IN THE NOAA ACTIVE REGION 12158

    Energy Technology Data Exchange (ETDEWEB)

    Vemareddy, P.; Ravindra, B. [Indian Institute of Astrophysics, Koramangala, Bangalore-560034 (India); Cheng, X., E-mail: vemareddy@iiap.res.in [School of Astronomy and Space Science, Nanjing University, Nanjing-210023 (China)

    2016-09-20

    We studied the development conditions of sigmoid structure under the influence of the magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from the Helioseismic Magnetic Imager and coronal EUV observations from the Atmospheric Imaging Assembly reveal that the erupting inverse-S sigmoid had roots at the location of the rotating sunspot. The sunspot rotates at a rate of 0°–5° h{sup −1} with increasing trend in the first half followed by a decrease. The time evolution of many non-potential parameters had a good correspondence with the sunspot rotation. The evolution of the AR magnetic structure is approximated by a time series of force-free equilibria. The non-linear force-free field magnetic structure around the sunspot manifests the observed sigmoid structure. Field lines from the sunspot periphery constitute the body of the sigmoid and those from the interior overlie the sigmoid, similar to a flux rope structure. While the sunspot was rotating, two major coronal mass ejection eruptions occurred in the AR. During the first (second) event, the coronal current concentrations were enhanced (degraded), consistent with the photospheric net vertical current; however, magnetic energy was released during both cases. The analysis results suggest that the magnetic connections of the sigmoid are driven by the slow motion of sunspot rotation, which transforms to a highly twisted flux rope structure in a dynamical scenario. Exceeding the critical twist in the flux rope probably leads to the loss of equilibrium, thus triggering the onset of the two eruptions.

  9. A New Revision of the Solar Irradiance Climate Data Record Incorporates Recent Research into Proxies of Sunspot Darkening and the Sunspot Number Record

    Science.gov (United States)

    Coddington, O.; Lean, J.; Pilewskie, P.; Baranyi, T.; Snow, M. A.; Kopp, G.; Richard, E. C.; Lindholm, C.

    2017-12-01

    An operational climate data record (CDR) of total and spectral solar irradiance became available in November 2015 as part of the National Oceanographic and Atmospheric Administration's National Centers for Environmental Information Climate Data Record Program. The data record, which is updated quarterly, is available from 1610 to the present as yearly-average values and from 1882 to the present as monthly- and daily-averages, with associated time and wavelength-dependent uncertainties. It was developed jointly by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics and the Naval Research Laboratory, and, together with the source code and supporting documentation, is available at https://www.ncdc.noaa.gov/cdr/. In the Solar Irradiance CDR, total solar irradiance (TSI) and solar spectral irradiance (SSI) are estimated from models that determine the changes from quiet Sun conditions arising from bright faculae and dark sunspots on the solar disk. The models are constructed using linear regression of proxies of solar sunspot and facular features with the approximately decade-long irradiance observations from the SOlar Radiation and Climate Experiment. A new revision of this data record was recently released in an ongoing effort to reduce solar irradiance uncertainties in two ways. First, the sunspot darkening proxy was revised using a new cross calibration of the current sunspot region observations made by the Solar Observing Optical Network with the historical records of the Royal Greenwich Observatory. This implementation affects modeled irradiances from 1882 - 1978. Second, the impact of a revised record of sunspot number by the Sunspot Index and Long-term Solar Observations center on modeled irradiances was assessed. This implementation provides two different reconstructions of historical, yearly-averaged irradiances from 1610-1881. Additionally, we show new, preliminary results that demonstrate improvements in modeled TSI by using

  10. The topside ionosphere above Arecibo at equinox during sunspot maximum

    International Nuclear Information System (INIS)

    Bailey, G.J.

    1980-01-01

    The coupled time-dependent 0 + and H + continuity and momentum equations and 0 + , H + and electron heat balance equations are solved simultaneously within the L = 1.4 (Arecibo) magnetic flux tube between an altitude of 120 km and the equatorial plane. The results of the calculations are used in a study of the topside ionosphere above Arecibo at equinox during sunspot maximum. Magnetically quiet conditions are assumed. The results of the calculations show that the L = 1.4 magnetic flux tube becomes saturated from an arbitrary state within 2-3 days. During the day the ion content of the magnetic flux tube consists mainly of 0 + whereas 0 + and H + are both important during the night. There is an altitude region in the topside ionosphere during the day where ion-counterstreaming occurs with H + flowing downward and 0 + flowing upward. The conditions causing this ion-counterstreaming are discussed. There is a net chemical gain of H + at the higher altitudes. This H + diffuses both upwards and downwards whilst 0 + diffuses upwards from its solar e.u.v. production source which is most important at the lower altitudes. During the night the calculated 0 + and H + temperatures are very nearly equal whereas during the day there are occasions when the H + temperature exceeds the 0 - temperature by about 300 K. (author)

  11. Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

    Science.gov (United States)

    Song, Donguk; Chae, Jongchul; Yurchyshyn, Vasyl; Lim, Eun-Kyung; Cho, Kyung-Suk; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah

    2017-02-01

    It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca II 8542 Å and Hα intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s-1 two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

  12. ENHANCEMENT OF A SUNSPOT LIGHT WALL WITH EXTERNAL DISTURBANCES

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shuhong; Zhang, Jun [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robert, E-mail: shuhongyang@nao.cas.cn [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2016-12-20

    Based on the Interface Region Imaging Spectrograph observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface and hits the light bridge (i.e., the base of the light wall), then sudden brightenings appear at the wall base followed by the rise of wall top, leading to an increase of the wall height. Once the brightness of the wall base fades, the height of the light wall begins to decrease. Five hours later, another nearby flare takes place, and a bright channel is formed that extends from the flare toward the light bridge. Although no obvious material flow along the bright channel is found, some ejected material is conjectured to reach the light bridge. Subsequently, the wall base brightens and the wall height begins to increase again. Once more, when the brightness of the wall base decays, the wall top fluctuates to lower heights. We suggest, based on the observed cases, that the interaction of falling material and ejected flare material with the light wall results in the brightenings of wall base and causes the height of the light wall to increase. Our results reveal that the light wall can be not only powered by the linkage of p -mode from below the photosphere, but may also be enhanced by external disturbances, such as falling material.

  13. Observations of Running Penumbral Waves Emerging in a Sunspot

    Science.gov (United States)

    Priya, T. G.; Wenda, Cao; Jiangtao, Su; Jie, Chen; Xinjie, Mao; Yuanyong, Deng; Robert, Erdélyi

    2018-01-01

    We present results from the investigation of 5 minute umbral oscillations in a single-polarity sunspot of active region NOAA 12132. The spectra of TiO, Hα, and 304 Å are used for corresponding atmospheric heights from the photosphere to lower corona. Power spectrum analysis at the formation height of Hα – 0.6 Å to the Hα center resulted in the detection of 5 minute oscillation signals in intensity interpreted as running waves outside the umbral center, mostly with vertical magnetic field inclination >15°. A phase-speed filter is used to extract the running wave signals with speed v ph > 4 km s‑1, from the time series of Hα – 0.4 Å images, and found twenty-four 3 minute umbral oscillatory events in a duration of one hour. Interestingly, the initial emergence of the 3 minute umbral oscillatory events are noticed closer to or at umbral boundaries. These 3 minute umbral oscillatory events are observed for the first time as propagating from a fraction of preceding running penumbral waves (RPWs). These fractional wavefronts rapidly separate from RPWs and move toward the umbral center, wherein they expand radially outwards suggesting the beginning of a new umbral oscillatory event. We found that most of these umbral oscillatory events develop further into RPWs. We speculate that the waveguides of running waves are twisted in spiral structures and hence the wavefronts are first seen at high latitudes of umbral boundaries and later at lower latitudes of the umbral center.

  14. On the Theory of Sunspots Proposed by Signor Kirchoff

    Directory of Open Access Journals (Sweden)

    Secchi A.

    2011-07-01

    Full Text Available Eileen Reeves (Department of Comparative Literature, Princeton University, Princeton, New Jersey, 08544 and Mary Posani (Department of French and Italian, The Ohio State University, Columbus, Ohio, 43221 provide a translation of Father Pietro Angelo Secchi’s classic work “ Secchi A. Sulla Teoria Delle Macchie Solari: Proposta dal sig. Kirchoff” as it appeared in Bullettino Meteorologico dell’ Osservatorio del Collegio Romano , 31 January 1864, v.3(4, 1–4. This was the first treatise to propose a partic- ulate photosphere floating on the gaseous body of the Sun. The idea would dominate astrophysical thought for the next 50 years. Secchi appears to have drafted the article, as a response to Gustav Kirchhoff’s proposal, echoing early Galilean ideas, that sunspots represented clouds which floated above the photosphere. Other than presenting a new solar model, noteworthy aspects of this work include Secchi’s appropriate insistence that materials do not emit the same light at the same temperature and his gentle rebuke of Kirchhoff relative to commenting on questions of astronomy.

  15. The use of solar faculae in studies of the sunspot cycle

    International Nuclear Information System (INIS)

    Brown, G.M.; Evans, R.

    1980-01-01

    Comparison of the long-term variation of photospheric faculae areas with that of sunspots shows that studies of faculae provide both complementary and supplementary information on the behaviour of the solar cycle. Detailed studies of the development of sunspots with respect to faculae show that there is a high degree of order over much of a given cycle, but marked differences from cycle to cycle. Within a cycle the relationship between spot and faculae areas appears to be similar for the N and S solar hemispheres, and over the early stages of a cycle it is directly related to the magnitude of the maximum sunspot number subsequently attained in that cycle. This result may well have predictive applications, and formulae are given relating the peak sunspot number to simple parameters derived from this early developmental stage. Full application to the current cycle 21 is denied due to the cessation of the Greenwich daily photoheliographic measurements, but use of the cruder weekly data suggests a maximum smoothed sunspot number of 150 +- 22. The effects of the incompatibility of the spot and faculae data, in that faculae are unobservable over a large fraction of the solar disc and also do not always develop associated spots, have been examined in a detailed study of two cycles and shown not to vitiate the results. (orig.)

  16. Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

    Energy Technology Data Exchange (ETDEWEB)

    Song, Donguk; Chae, Jongchul; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Yurchyshyn, Vasyl [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314-9672 (United States); Lim, Eun-Kyung; Cho, Kyung-Suk, E-mail: dusong@astro.snu.ac.kr [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)

    2017-02-01

    It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca ii 8542 Å and H α intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s{sup −1} two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

  17. MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

    International Nuclear Information System (INIS)

    Zhao, Hui; Chou, Dean-Yi

    2016-01-01

    The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ ab and the scattering cross section σ sc for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ ab and σ sc , the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ ab of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ sc of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ ab is approximately proportional to the sunspot radius, while the dependence of σ sc on radius is faster than the linear increase.

  18. MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hui [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 200012 (China); Chou, Dean-Yi, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

    2016-05-01

    The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ {sub ab} and the scattering cross section σ {sub sc} for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ {sub ab} and σ {sub sc}, the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ {sub ab} of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ {sub sc} of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ {sub ab} is approximately proportional to the sunspot radius, while the dependence of σ {sub sc} on radius is faster than the linear increase.

  19. Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

    Science.gov (United States)

    Rosenthal, C. S.

    1992-01-01

    Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

  20. On the determination of heliographic positions and rotation velocities of sunspots. Pt. 2

    International Nuclear Information System (INIS)

    Balthasar, H.

    1983-01-01

    Using sunspot positions of small sunspots observed at Debrecen and Locarno as well as positions of recurrent sunspots taken from the Greenwich Photoheliographic Results (1940-1976) the influence of the Wilson depression on the rotation velocities was investigated. It was found that the Wilson depression can be determined by minimizing errors of the rotation velocities or minimizing the differences of rotation velocities determined from disk passages and central meridian passages. The Wilson depressions found were between 765 km and 2500 km for the first sample while they were between 0 km and several 1000 km for the second sample. The averaged Wilson depression for the second sample is between 500 km and 965 km depending on the reduction method. A dependence of the Wilson depression on the age of the spots investigated seems not to exist. (orig.)

  1. Relationship between geomagnetic classes’ activity phases and their occurrence during the sunspot cycle

    Directory of Open Access Journals (Sweden)

    Frédéric Ouattara

    2009-06-01

    Full Text Available Four well known geomagnetic classes of activity such as quiet days activity, fluctuating activity, recurrent activity
    and shock activity time occurrences have been determined not only by using time profile of sunspot number
    Rz but also by using aa index values.
    We show that recurrent wind stream activity and fluctuating activity occur in opposite phase and slow solar wind
    activity during minimum phase and shock activity at the maximum phase.
    It emerges from this study that fluctuating activity precedes the sunspot cycle by π/2 and the latter also precedes
    recurrent activity by π/2. Thus in the majority the activities do not happen at random; the sunspot cycle starts
    with quiet days activity, continues with fluctuating activity and during its maximum phase arrives shock activity.
    The descending phase is characterized by the manifestation of recurrent wind stream activity.

  2. Possibility to explain the temperature distribution in sunspots by an anisotropic heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Eschrich, K O; Krause, F [Akademie der Wissenschaften der DDR, Potsdam. Zentralinstitut fuer Astrophysik

    1977-01-01

    Numerical solutions of a heat conduction problem in an anisotropic medium are used for a discussion of the possibility to explain the temperature distribution in sunspots and their environment. The anisotropy is assumed being due to the strong magnetic field in sunspots and the region below. This magnetic field forces the convection to take an anisotropic structure (two-dimensional turbulence) and thus the region gets anisotropic conduction properties, on the average. The discussion shows that the observed temperature profiles can be explained in the case the depth of the region of anisotropy is about as large as the diameter of the spot or larger.

  3. Outflow of chromospheric emission features from the rim of a sunspot

    Science.gov (United States)

    Liu, S.-Y.

    1973-01-01

    In viewing a 16 mm movie made from a time sequence of spectroheliograms, some of these emission features are found to move outward from the rim of the sunspot until they are eventually lost in the small plage. There are two interpretations for the streaming of the magnetic features. It is possible that kinks in the line of force propagate along a horizontal extension of the penumbral magnetic field. Alternatively, fragments of the sunspot magnetic field are carried away by the photospheric velocity field.

  4. Empirical mode decomposition and long-range correlation analysis of sunspot time series

    International Nuclear Information System (INIS)

    Zhou, Yu; Leung, Yee

    2010-01-01

    Sunspots, which are the best known and most variable features of the solar surface, affect our planet in many ways. The number of sunspots during a period of time is highly variable and arouses strong research interest. When multifractal detrended fluctuation analysis (MF-DFA) is employed to study the fractal properties and long-range correlation of the sunspot series, some spurious crossover points might appear because of the periodic and quasi-periodic trends in the series. However many cycles of solar activities can be reflected by the sunspot time series. The 11-year cycle is perhaps the most famous cycle of the sunspot activity. These cycles pose problems for the investigation of the scaling behavior of sunspot time series. Using different methods to handle the 11-year cycle generally creates totally different results. Using MF-DFA, Movahed and co-workers employed Fourier truncation to deal with the 11-year cycle and found that the series is long-range anti-correlated with a Hurst exponent, H, of about 0.12. However, Hu and co-workers proposed an adaptive detrending method for the MF-DFA and discovered long-range correlation characterized by H≈0.74. In an attempt to get to the bottom of the problem in the present paper, empirical mode decomposition (EMD), a data-driven adaptive method, is applied to first extract the components with different dominant frequencies. MF-DFA is then employed to study the long-range correlation of the sunspot time series under the influence of these components. On removing the effects of these periods, the natural long-range correlation of the sunspot time series can be revealed. With the removal of the 11-year cycle, a crossover point located at around 60 months is discovered to be a reasonable point separating two different time scale ranges, H≈0.72 and H≈1.49. And on removing all cycles longer than 11 years, we have H≈0.69 and H≈0.28. The three cycle-removing methods—Fourier truncation, adaptive detrending and the

  5. A SOLAR FLARE DISTURBING A LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Leping; Li, Xiaohong, E-mail: yijunhou@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2016-10-01

    With the high-resolution data from the Interface Region Imaging Spectrograph , we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 Å slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare’s one ribbon overlapped the light bridge, which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 to 1.6 Mm before the flare and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upward at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall’s projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site, and the light wall inclines. Thus, the projective amplitude notably decrease at the post-flare stage.

  6. A SOLAR FLARE DISTURBING A LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

    International Nuclear Information System (INIS)

    Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Leping; Li, Xiaohong

    2016-01-01

    With the high-resolution data from the Interface Region Imaging Spectrograph , we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 Å slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare’s one ribbon overlapped the light bridge, which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 to 1.6 Mm before the flare and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upward at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall’s projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site, and the light wall inclines. Thus, the projective amplitude notably decrease at the post-flare stage.

  7. CHROMOSPHERIC SUNSPOTS IN THE MILLIMETER RANGE AS OBSERVED BY THE NOBEYAMA RADIOHELIOGRAPH

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, Kazumasa [National Institute of Information and Communications Technology, Koganei 184-8795, Tokyo (Japan); Koshiishi, Hideki [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, Tsukuba 305-8505 (Japan); Shibasaki, Kiyoto [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Nagano 384-1305 (Japan); Nozawa, Satoshi; Miyawaki, Shun; Yoneya, Takuro, E-mail: kazumasa.iwai@nict.go.jp [Department of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan)

    2016-01-10

    We investigate the upper chromosphere and the transition region of the sunspot umbra using the radio brightness temperature at 34 GHz (corresponding to 8.8 mm observations) as observed by the Nobeyama Radioheliograph (NoRH). Radio free–free emission in the longer millimeter range is generated around the transition region, and its brightness temperature yields the region's temperature and density distribution. We use the NoRH data at 34 GHz by applying the Steer-CLEAN image synthesis. These data and the analysis method enable us to investigate the chromospheric structures in the longer millimeter range with high spatial resolution and sufficient visibilities. We also perform simultaneous observations of one sunspot using the NoRH and the Nobeyama 45 m telescope operating at 115 GHz. We determine that 115 GHz emission mainly originates from the lower chromosphere while 34 GHz emission mainly originates from the upper chromosphere and transition region. These observational results are consistent with the radio emission characteristics estimated from current atmospheric models of the chromosphere. On the other hand, the observed brightness temperature of the umbral region is almost the same as that of the quiet region. This result is inconsistent with current sunspot models, which predict a considerably higher brightness temperature of the sunspot umbra at 34 GHz. This inconsistency suggests that the temperature of the region at which the 34 GHz radio emission becomes optically thick should be lower than that predicted by the models.

  8. Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396

    Czech Academy of Sciences Publication Activity Database

    Verma, M.; Denker, C.; Boehm, F.; Balthasar, H.; Fischer, C.E.; Kuckein, C.; Gonzalez, N.B.; Berkefeld, T.; Collados Vera, M.; Diercke, A.; Feller, A.; Gonzalez Manrique, S. J.; Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, Michal; Solanki, S.K.; Soltau, D.; Staude, J.; Strassmeier, K.G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.A.

    2016-01-01

    Roč. 337, č. 10 (2016), s. 1090-1098 ISSN 0004-6337. [Dynamic Sun - Exploring the Many Facets of Solar Eruptive Events. Potsdam, 26.10. 2015 -29.10. 2015 ] Institutional support: RVO:67985815 Keywords : Sun * magnetic fields * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.916, year: 2016

  9. Physical Properties of Umbral Dots Observed in Sunspots: A Hinode Observation

    Science.gov (United States)

    Yadav, Rahul; Mathew, Shibu K.

    2018-04-01

    Umbral dots (UDs) are small-scale bright features observed in the umbral part of sunspots and pores. It is well established that they are manifestations of magnetoconvection phenomena inside umbrae. We study the physical properties of UDs in different sunspots and their dependence on decay rate and filling factor. We have selected high-resolution, G-band continuum filtergrams of seven sunspots from Hinode to study their physical properties. We have also used Michelson Doppler Imager (MDI) continuum images to estimate the decay rate of selected sunspots. An identification and tracking algorithm was developed to identify the UDs in time sequences. The statistical analysis of UDs exhibits an averaged maximum intensity and effective diameter of 0.26 I_{QS} and 270 km. Furthermore, the lifetime, horizontal speed, trajectory length, and displacement length (birth-death distance) of UDs are 8.19 minutes, 0.5 km s-1, 284 km, and 155 km, respectively. We also find a positive correlation between intensity-diameter, intensity-lifetime, and diameter-lifetime of UDs. However, UD properties do not show any significant relation with the decay rate or filling factor.

  10. Predicting Maximum Sunspot Number in Solar Cycle 24 Nipa J Bhatt ...

    Indian Academy of Sciences (India)

    Key words. Sunspot number—precursor prediction technique—geo- magnetic activity index aa. 1. Introduction. Predictions of solar and geomagnetic activities are important for various purposes, including the operation of low-earth orbiting satellites, operation of power grids on. Earth, and satellite communication systems.

  11. COMPARISON OF CHAOTIC AND FRACTAL PROPERTIES OF POLAR FACULAE WITH SUNSPOT ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Deng, L. H.; Xiang, Y. Y.; Dun, G. T. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216 (China); Li, B., E-mail: wooden@escience.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, Weihai 264209 (China)

    2016-01-15

    The solar magnetic activity is governed by a complex dynamo mechanism and exhibits a nonlinear dissipation behavior in nature. The chaotic and fractal properties of solar time series are of great importance to understanding the solar dynamo actions, especially with regard to the nonlinear dynamo theories. In the present work, several nonlinear analysis approaches are proposed to investigate the nonlinear dynamical behavior of the polar faculae and sunspot activity for the time interval from 1951 August to 1998 December. The following prominent results are found: (1) both the high- and the low-latitude solar activity are governed by a three-dimensional chaotic attractor, and the chaotic behavior of polar faculae is the most complex, followed by that of the sunspot areas, and then the sunspot numbers; (2) both the high- and low-latitude solar activity exhibit a high degree of persistent behavior, and their fractal nature is due to such long-range correlation; (3) the solar magnetic activity cycle is predictable in nature, but the high-accuracy prediction should only be done for short- to mid-term due to its intrinsically dynamical complexity. With the help of the Babcock–Leighton dynamo model, we suggest that the nonlinear coupling of the polar magnetic fields with strong active-region fields exhibits a complex manner, causing the statistical similarities and differences between the polar faculae and the sunspot-related indicators.

  12. Fine structure in sunspots. IV. Penumbral grains in speckle reconstucted images

    Czech Academy of Sciences Publication Activity Database

    Sobotka, Michal; Suetterlin, P.

    2001-01-01

    Roč. 380, č. 2 (2001), s. 714-718 ISSN 0004-6361 R&D Projects: GA AV ČR KSK2043105; GA AV ČR IAA3003903 Institutional research plan: CEZ:AV0Z1003909 Keywords : sun * sunspots Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.790, year: 2000

  13. Preliminary results from the orbiting solar observatory 8: Transition-zone dynamics over a sunspot

    International Nuclear Information System (INIS)

    Bruner, E.C. Jr.; Chipman, E.G.; Lites, B.W.; Rottman, G.J.; Shine, R.A.; Athay, R.G.; White, O.R.

    1976-01-01

    The University of Colorado experiment aboard OSO-8 observed the C IV 1548 A line in the bright plume over a sunspot. Transient redshifts at 5 minute intervals were studied, but the expected phenomena associated with simple Alfven wave effects were not observed

  14. Temperature mapping of sunspots and pores from speckle reconstructed three colour photometry

    NARCIS (Netherlands)

    Sütterlin, P.; Wiehr, E.

    1998-01-01

    The two-dimensional temperature distribution in a highly structured sunspot and in two small umbrae is determined from a three-colour photometry in narrow spectral continua. Disturbing influences from the earth’s atmosphere are removed by speckle masking techniques, yielding a spatial resolution

  15. Deciphering solar magnetic activity. I. On the relationship between the sunspot cycle and the evolution of small magnetic features

    Energy Technology Data Exchange (ETDEWEB)

    McIntosh, Scott W.; Wang, Xin; Markel, Robert S.; Thompson, Michael J. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J.; Malanushenko, Anna V. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Davey, Alisdair R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howe, Rachel [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Krista, Larisza D. [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80205 (United States); Cirtain, Jonathan W. [Marshall Space Flight Center, Code ZP13, Huntsville, AL 35812 (United States); Gurman, Joseph B.; Pesnell, William D., E-mail: mscott@ucar.edu [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-09-01

    Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ∼22 yr. The principal variation of sunspots, an ∼11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability.

  16. A model of a sunspot chromosphere based on OSO 8 observations

    Science.gov (United States)

    Lites, B. W.; Skumanich, A.

    1982-01-01

    OSO 8 spectrometer observations of the H I, Mg II, and Ca II resonance lines of a large quiet sunspot during November 16-17, 1975, along with a C IV line of that event obtained by a ground-based spectrometer, are analyzed together with near-simultaneous ground-based Stokes measurements to yield an umbral chromosphere and transition region model. Features of this model include a chromosphere that is effectively thin in the resonance lines of H I and Mg II, while being saturated in Ca II, and an upper chromospheric structure similar to that of quiet-sun models. The similarity of the upper chromosphere of the sunspot umbra to the quiet-sun chromosphere suggests that the intense magnetic field plays only a passive role in the chromospheric heating mechanism, and the observations cited indicate that solar-type stars with large areas of ordered magnetic flux would not necessarily exhibit extremely active chromosphere.

  17. Sunspot variation and selected associated phenomena: a look at solar cycle 21 and beyond

    International Nuclear Information System (INIS)

    Wilson, R.M.

    1982-02-01

    Solar sunspot cycles 8 through 21 are reviewed. Mean time intervals are calculated for maximum to maximum, minimum to minimum, minimum to maximum, and maximum to minimum phases for cycles 8 through 20 and 8 through 21. Simple cosine functions with a period of 132 years are compared to, and found to be representative of, the variation of smoothed sunspot numbers at solar maximum and minimum. A comparison of cycles 20 and 21 is given, leading to a projection for activity levels during the Spacelab 2 era (tentatively, November 1984). A prediction is made for cycle 22. Major flares are observed to peak several months subsequent to the solar maximum during cycle 21 and to be at minimum level several months after the solar minimum. Additional remarks are given for flares, gradual rise and fall radio events and 2800 MHz radio emission. Certain solar activity parameters, especially as they relate to the near term Spacelab 2 time frame are estimated

  18. The chromosphere above a δ-sunspot in the presence of fan-shaped jets

    Science.gov (United States)

    Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodríguez, Jaime

    2018-01-01

    Context. Delta-sunspots are known to be favourable locations for fast and energetic events like flares and coronal mass ejections. The photosphere of this sunspot type has been thoroughly investigated in the past three decades. The atmospheric conditions in the chromosphere are not as well known, however. Aims: This study is focused on the chromosphere of a δ-sunspot that harbours a series of fan-shaped jets in its penumbra. The aim of this study is to establish the magnetic field topology and the temperature distribution in the presence of jets in the photosphere and the chromosphere. Methods: We use data from the Swedish 1m Solar Telescope (SST) and the Solar Dynamics Observatory. We invert the spectropolarimetric Fe I 6302 Å and Ca II 8542 Å data from the SST using the non-LTE inversion code NICOLE to estimate the magnetic field configuration, temperature, and velocity structure in the chromosphere. Results: A loop-like magnetic structure is observed to emerge in the penumbra of the sunspot. The jets are launched from this structure. Magnetic reconnection between this emerging field and the pre-existing vertical field is suggested by hot plasma patches on the interface between the two fields. The height at which the reconnection takes place is located between log τ500 = -2 and log τ500 = -3. The magnetic field vector and the atmospheric temperature maps show a stationary configuration during the whole observation. Movies associated to Figs. 3-5 are available at http://www.aanda.org

  19. ASYMMETRIC SUNSPOT ACTIVITY AND THE SOUTHWARD DISPLACEMENT OF THE HELIOSPHERIC CURRENT SHEET

    International Nuclear Information System (INIS)

    Wang, Y.-M.; Robbrecht, E.

    2011-01-01

    Observations of the interplanetary magnetic field (IMF) have suggested a statistical tendency for the heliospheric current sheet (HCS) to be shifted a few degrees southward of the heliographic equator during the period 1965-2010, particularly in the years near sunspot minimum. Using potential-field source-surface extrapolations and photospheric flux-transport simulations, we demonstrate that this southward displacement follows from Joy's law and the observed hemispheric asymmetry in the sunspot numbers, with activity being stronger in the southern (northern) hemisphere during the declining (rising) phase of cycles 20-23. The hemispheric asymmetry gives rise to an axisymmetric quadrupole field, whose equatorial zone has the sign of the leading-polarity flux in the dominant hemisphere; during the last four cycles, the polarity of the IMF around the equator thus tended to match that of the north polar field both before and after polar field reversal. However, large fluctuations are introduced by the nonaxisymmetric field components, which depend on the longitudinal distribution of sunspot activity in either hemisphere. Consistent with this model, the HCS showed an average northward displacement during cycle 19, when the 'usual' alternation was reversed and the northern hemisphere became far more active than the southern hemisphere during the declining phase of the cycle. We propose a new method for determining the north-south displacement of the HCS from coronal streamer observations.

  20. MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

    2009-01-01

    The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

  1. A magnetic neutral sheet as cause of the flare productivity of a delta sunspot group

    International Nuclear Information System (INIS)

    Seehafer, N.

    1985-01-01

    Flare observations in the solar activity complex HR 16862, 16863, 16864 at the end of May 1980 are compared with the structure of force-free magnetic fields calculated from photospheric magnetograph measurements. A series of homologous flares connected with a delta configuration in HR 16864 was possibly caused by a magnetic neutral sheet. The delta configuration consisted of the large preceding spot of HR 16864 and a small satellite of opposite polarity. All magnetic flux from the satellite is connected to the main spot, and at the outer edge of the satellite, away from the main spot, a magnetic neutral sheet is found. This agrees with the observation that all penumbra was situated between parent spot and satellite, which is typical of such delta configurations. It is suggested that the flare productivity of these configurations is generally caused by magnetic neutral sheets at the penumbra-free outer boundary of the satellites. (author)

  2. On the relation between activity-related frequency shifts and the sunspot distribution over the solar cycle 23

    Directory of Open Access Journals (Sweden)

    Santos Ângela R. G.

    2017-01-01

    Full Text Available The activity-related variations in the solar acoustic frequencies have been known for 30 years. However, the importance of the different contributions is still not well established. With this in mind, we developed an empirical model to estimate the spot-induced frequency shifts, which takes into account the sunspot properties, such as area and latitude. The comparison between the model frequency shifts obtained from the daily sunspot records and those observed suggests that the contribution from a stochastic component to the total frequency shifts is about 30%. The remaining 70% is related to a global, long-term variation. We also propose a new observable to investigate the short-and mid-term variations of the frequency shifts, which is insensitive to the long-term variations contained in the data. On the shortest time scales the variations in the frequency shifts are strongly correlated with the variations in the total area covered by sunspots. However, a significant loss of correlation is still found, which cannot be fully explained by ignoring the invisible side of the Sun when accounting for the total sunspot area. We also verify that the times when the frequency shifts and the sunspot areas do not vary in a similar way tend to coincide with the times of the maximum amplitude of the quasi-biennial variations found in the seismic data.

  3. Records of auroral candidates and sunspots in Rikkokushi, chronicles of ancient Japan from early 7th century to 887

    Science.gov (United States)

    Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Ebihara, Yusuke; Kawamura, Akito Davis; Isobe, Hiroaki; Namiki, Katsuko; Shibata, Kazunari

    2017-12-01

    We present the results of the surveys on sunspots and auroral candidates in Rikkokushi, Japanese official histories from the early 7th century to 887, to review the solar and auroral activities. In total, we found one sunspot record and 13 auroral candidates in Rikkokushi. We then examine the records of the sunspots and auroral candidates, compare the auroral candidates with the lunar phase to estimate their reliability, and compare the records of the sunspots and auroral candidates with the contemporary total solar irradiance reconstructed from radioisotope data. We also identify the locations of the observational sites to review possible equatorward expansion of the auroral oval. These discussions suggest a major gap in auroral candidates from the late 7th to early 9th centuries, which includes the candidate of the grand minimum reconstructed from the radioisotope data, a similar tendency as the distributions of sunspot records in contemporary China, and a relatively high magnetic latitude of observational sites with a higher potential for observing aurorae more frequently than at present.

  4. On Solar Granulations, Limb Darkening, and Sunspots: Brief Insights in Remembrance of Father Angelo Secchi

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2011-07-01

    Full Text Available Father Angelo Secchi used the existence of solar granulation as a central line of rea- soning when he advanced that the Sun was a gaseous body with a photosphere contain- ing incandescent particulate matter (Secchi A. Sulla Struttura della Fotosfera Solare. Bullettino Meteorologico dell’Osservatorio del Collegio Romano , 30 November 1864, v.3(11, 1–3. Secchi saw the granules as condensed matter emitting the photospheric spectrum, while the darkened intergranular lanes conveyed the presence of a gaseous solar interior. Secchi also considered the nature of sunspots and limb darkening. In the context of modern solar models, opacity arguments currently account for the emis- sive properties of the photosphere. Optical depth is thought to explain limb darkening. Both temperature variations and magnetic fields are invoked to justify the weakened emissivities of sunspots, even though the presence of static magnetic fields in materi- als is not usually associated with modified emissivity. Conversely, within the context of a liquid metallic hydrogen solar model, the appearance of granules, limb darkening, and sunspots can be elegantly understood through the varying directional emissivity of condensed matter. A single explanation is applicable to all three phenomena. Granular contrast can be directly associated with the generation of limb darkening. Depending on size, granules can be analyzed by considering Kolmogoroff’s formulations and B ́ enard convection, respectively, both of which were observed using incompressible liquids, not gases. Granules follow the 2-dimensional space filling laws of Aboav-Weiner and Lewis. Their adherence to these structural laws provides supportive evidence that the granular surface of the Sun represents elements which can only be constructed from condensed matter. A gaseous Sun cannot be confined to a 2-dimensional framework. Mesogranules, supergranules, and giant cells constitute additional entities which further

  5. The Formation of a Sunspot Penumbra Sector in Active Region NOAA 12574

    Science.gov (United States)

    Li, Qiaoling; Yan, Xiaoli; Wang, Jincheng; Kong, DeFang; Xue, Zhike; Yang, Liheng; Cao, Wenda

    2018-04-01

    We present a particular case of the formation of a penumbra sector around a developing sunspot in the active region NOAA 12574 on 2016 August 11 by using the high-resolution data observed by the New Solar Telescope at the Big Bear Solar Observatory and the data acquired by the Helioseismic and Magnetic Imager and the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory satellite. Before the new penumbra sector formed, the developing sunspot already had two umbrae with some penumbral filaments. The penumbra sector gradually formed at the junction of two umbrae. We found that the formation of the penumbra sector can be divided into two stages. First, during the initial stage of penumbral formation, the region where the penumbra sector formed always appeared blueshifted in a Dopplergram. The area, mean transverse magnetic field strength, and total magnetic flux of the umbra and penumbra sector all increased with time. The initial penumbral formation was associated with magnetic emergence. Second, when the penumbra sector appeared, the magnetic flux and area of the penumbra sector increased after the umbra’s magnetic flux and area decreased. These results indicate that the umbra provided magnetic flux for penumbral development after the penumbra sector appeared. We also found that the newly formed penumbra sector was associated with sunspot rotation. Based on these findings, we suggest that the penumbra sector was the result of the emerging flux that was trapped in the photosphere at the initial stage of penumbral formation, and when the rudimentary penumbra formed, the penumbra sector developed at the cost of the umbra.

  6. LOOKING FOR GRANULATION AND PERIODICITY IMPRINTS IN THE SUNSPOT TIME SERIES

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silva, Hugo G., E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: hgsilva@uevora.pt [Departamento de Física, ECT, Instituto de Ciências da Terra, Universidade de Évora, Rua Romão Ramalho 59, 7002-554 Évora (Portugal)

    2015-05-10

    The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum power spectral density occurs at 22.67 days. This value is part of the 22–27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be produced by convective flows inside the star. The study clearly shows a north–south asymmetry. The 18.43 yr periodical source is correlated between the two hemispheres, but the 22.67 day one is not correlated. It is shown that toward the large timescales an excess occurs in the northern hemisphere, especially near the previous two periodic sources. To further investigate the 22.67 day periodicity, we made a Lomb–Scargle spectral analysis. The study suggests that this periodicity is distinct from others found nearby.

  7. THE FORMATION OF AN INVERSE S-SHAPED ACTIVE-REGION FILAMENT DRIVEN BY SUNSPOT MOTION AND MAGNETIC RECONNECTION

    Energy Technology Data Exchange (ETDEWEB)

    Yan, X. L.; Xue, Z. K.; Wang, J. C.; Yang, L. H. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Priest, E. R. [Mathematics Institute, University of St Andrews, St Andrews, KY16 9SS (United Kingdom); Guo, Q. L., E-mail: yanxl@ynao.ac.cn [College of Mathematics Physics and Information Engineering, Jiaxing University, Jiaxing 314001 (China)

    2016-11-20

    We present a detailed study of the formation of an inverse S-shaped filament prior to its eruption in active region NOAA 11884 from 2013 October 31 to November 2. In the initial stage, clockwise rotation of a small positive sunspot around the main negative trailing sunspot formed a curved filament. Then the small sunspot cancelled with the negative magnetic flux to create a longer active-region filament with an inverse S-shape. At the cancellation site a brightening was observed in UV and EUV images and bright material was transferred to the filament. Later the filament erupted after cancellation of two opposite polarities below the upper part of the filament. Nonlinear force-free field extrapolation of vector photospheric fields suggests that the filament may have a twisted structure, but this cannot be confirmed from the current observations.

  8. Relation of flare activity to the approach and separation of sunspots in an active region and to its magnetic properties

    International Nuclear Information System (INIS)

    Markova, E.

    1978-01-01

    The relation between the flare activity of active regions within the scope of a large complex and the magnetic gradients of these active regions and their daily variations is investigated in the interval of the exceptionally high flare activity occurring in June 1970. New indices, characterizing the active region, were defined, e.g., the instantaneous sunspot-area density and the instantaneous sunspot-number density. These indices were determined on the basis of measurements of the surface containing all sunspots of the complex of active regions enclosed by an envelope. An attempt was made to substitute the surface in the relation for the individual indices by distance. The daily variations of these indices were again compared with the flare activity and some mutual relations were derived. (author)

  9. Questioning the Influence of Sunspots on Amazon Hydrology: Even a Broken Clock Tells the Right Time Twice a Day

    Science.gov (United States)

    Baker, J. C. A.; Gloor, M.; Boom, A.; Neill, D. A.; Cintra, B. B. L.; Clerici, S. J.; Brienen, R. J. W.

    2018-02-01

    It was suggested in a recent article that sunspots drive decadal variation in Amazon River flow. This conclusion was based on a novel time series decomposition method used to extract a decadal signal from the Amazon River record. We have extended this analysis back in time, using a new hydrological proxy record of tree ring oxygen isotopes (δ18OTR). Consistent with the findings of Antico and Torres, we find a positive correlation between sunspots and the decadal δ18OTR cycle from 1903 to 2012 (r = 0.60, p r = -0.30, p = 0.11, 1799-1902). This result casts considerable doubt over the mechanism by which sunspots are purported to influence Amazon hydrology.

  10. Using dynamo theory to predict the sunspot number during solar cycle 21

    Science.gov (United States)

    Schatten, K. H.; Scherrer, P. H.; Svalgaard, L.; Wilcox, J. M.

    1978-01-01

    On physical grounds it is suggested that the polar field strength of the sun near a solar minimum is closely related to the solar activity of the following cycle. Four methods of estimating the polar magnetic field strength of the sun near solar minimum are employed to provide an estimate of the yearly mean sunspot number of cycle 21 at solar maximum of 140 + or - 20. This estimate may be considered a first-order attempt to predict the cycle activity using one parameter of physical importance based upon dynamo theory.

  11. Magnetic fields and proper motions of sunspots. 1

    International Nuclear Information System (INIS)

    Kalman, B.

    1976-01-01

    Determining relation between magnetic fields and intrinsic motions of the Sun spots is considered. Based on daily maps of the longitudinal H 1 and transverse H 2 constituents of the magnetic field and a series of photographs of the Sun a comparison was made of motion of shadow nuclei and semishadow fibres with the structure of the magnetic field in the Sun spot group from 7 till 14 of June, 1969. It was found that the spots moved both along and across the direction of the transverse magnetic field. During the movement of spots changes in the structure of H 2 occurred which in the most cases corresponded to reorientation of lines of force along the trajectory behind the moving spot. However, in some cases the structure of the transverse field behind the moving spot became close to the perpendicular one to the trajectory of the past spot, although it could be almost parallel to the trajectory in front of the spot. The best coincidence of orientations of the spot trajectories with the H 2 structure was obtained near the zero line of the longitudinal field. The orientation of fibres of semishadows along H 2 was observed when the group was near the central meridian

  12. Solar magnetic field studies using the 12 micron emission lines. II - Stokes profiles and vector field samples in sunspots

    Science.gov (United States)

    Hewagama, Tilak; Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Zipoy, David; Mickey, Donald L.; Garcia, Howard

    1993-01-01

    Polarimetric observations at 12 microns of two sunpots are reported. The horizontal distribution of parameters such as magnetic field strength, inclination, azimuth, and magnetic field filling factors are presented along with information about the height dependence of the magnetic field strength. Comparisons with contemporary magnetostatic sunspot models are made. The magnetic data are used to estimate the height of 12 micron line formation. From the data, it is concluded that within a stable sunspot there are no regions that are magnetically filamentary, in the sense of containing both strong-field and field-free regions.

  13. On the statistical aspects of sunspot number time series and its association with the summer-monsoon rainfall over India

    Science.gov (United States)

    Chattopadhyay, Surajit; Chattopadhyay, Goutami

    The present paper reports studies on the association between the mean annual sunspot numbers and the summer monsoon rainfall over India. The cross correlations have been studied. After Box-Cox transformation, the time spectral analysis has been executed and it has been found that both of the time series have an important spectrum at the fifth harmonic. An artificial neural network (ANN) model has been developed on the data series averaged continuously by five years and the neural network could establish a predictor-predict and relationship between the sunspot numbers and the mean yearly summer monsoon rainfall over India.

  14. WAVES AS THE SOURCE OF APPARENT TWISTING MOTIONS IN SUNSPOT PENUMBRAE

    International Nuclear Information System (INIS)

    Bharti, L.; Cameron, R. H.; Hirzberger, J.; Solanki, S. K.; Rempel, M.

    2012-01-01

    The motion of dark striations across bright filaments in a sunspot penumbra has become an important new diagnostic of convective gas flows in penumbral filaments. The nature of these striations has, however, remained unclear. Here, we present an analysis of small-scale motions in penumbral filaments in both simulations and observations. The simulations, when viewed from above, show fine structure with dark lanes running outward from the dark core of the penumbral filaments. The dark lanes either occur preferentially on one side or alternate between both sides of the filament. We identify this fine structure with transverse (kink) oscillations of the filament, corresponding to a sideways swaying of the filament. These oscillations have periods in the range of 5-7 minutes and propagate outward and downward along the filament. Similar features are found in observed G-band intensity time series of penumbral filaments in a sunspot located near disk center obtained by the Broadband Filter Imager on board the Hinode. We also find that some filaments show dark striations moving to both sides of the filaments. Based on the agreement between simulations and observations we conclude that the motions of these striations are caused by transverse oscillations of the underlying bright filaments.

  15. The mutual attraction of magnetic knots. [solar hydromagnetic instability in sunspot regions

    Science.gov (United States)

    Parker, E. N.

    1978-01-01

    It is observed that the magnetic knots associated with active regions on the sun have an attraction for each other during the formative period of the active regions, when new magnetic flux is coming to the surface. The attraction disappears when new flux ceases to rise through the surface. Then the magnetic spots and knots tend to come apart, leading to disintegration of the sunspots previously formed. The dissolution of the fields is to be expected, as a consequence of the magnetic repulsion of knots of like polarity and as a consequence of the hydromagnetic exchange instability. The purpose of this paper is to show that the mutual attraction of knots during the formative stages of a sunspot region may be understood as the mutual hydrodynamic attraction of the rising flux tubes. Two rising tubes attract each other, as a consequence of the wake of the leading tube when one is moving behind the other, and as a consequence of the Bernoulli effect when rising side by side.

  16. Sunspots and the physics of magnetic flux tubes in the sun

    International Nuclear Information System (INIS)

    Ballegooijen, A.A. van.

    1982-01-01

    This thesis refers to the sub-surface structure of the solar magnetic field. Following an introductory chapter, chapter II presents an analysis of spectroscopic observations of a sunspot at infrared wavelengths and models of the temperature stratification in the sunspot atmosphere are derived. The main subject of this thesis concerns the structure of the magnetic field deep down below the stellar surface, near the base of the convective envelope. In Chapter III the stability of toroidal flux tubes to wave-like perturbations is discussed, assuming that the tubes are neutrally buoyant. A model is proposed in which the toroidal flux tubes are neutrally buoyant and located in a stably stratified layer just below the base of the convective zone. On the basis of some simple assumptions for the temperature stratification in this storage layer the author considers in Chapter IV the properties of the vertical flux tubes in the convective zone. The adiabatic flux model cannot satisfactorily be applied to the simplified model of the storage layer, so that the problem of magnetic flux storage is reconsidered in Chapter V. A new model of the temperature stratification at the interface of convective zone and radiative interior of the sun is described. Finally, in Chapter VI, the stability of toroidal flux tubes in a differentially rotating star are discussed. It is demonstrated that for realistic values of the magnetic field strength, rotation has a strong effect on the stability of the toroidal flux tubes. (C.F.)

  17. NARROW-LINE-WIDTH UV BURSTS IN THE TRANSITION REGION ABOVE SUNSPOTS OBSERVED BY IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Zhenyong; Huang, Zhenghua; Xia, Lidong; Li, Bo; Madjarska, Maria S.; Fu, Hui; Mou, Chaozhou; Xie, Haixia, E-mail: z.huang@sdu.edu.cn, E-mail: xld@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China)

    2016-10-01

    Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si iv line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two data sets (a raster and a sit-and-stare data set). Among these, four events are short-lived with a duration of ∼10 minutes, while two last for more than 36 minutes. All NUBs have Doppler shifts of 15–18 km s{sup −1}, while the NUB found in sit-and-stare data possesses an additional component at ∼50 km s{sup −1} found only in the C ii and Mg ii lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots.

  18. The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, S. Krishna; Jess, D. B. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN (United Kingdom); Doorsselaere, T. Van [Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Verth, G. [School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom); Morton, R. J. [Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Ellison Building, Newcastle upon Tyne, NE1 8ST (United Kingdom); Fedun, V. [Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom); Erdélyi, R. [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Christian, D. J., E-mail: krishna.prasad@qub.ac.uk [Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States)

    2017-09-20

    High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition region heights. Power spectra are generated from intensity oscillations in sunspot umbra, across multiple atmospheric heights, for frequencies up to a few hundred mHz. It is observed that the power spectra display a power-law dependence over the entire frequency range, with a significant enhancement around 5.5 mHz found for the chromospheric channels. The phase difference spectra reveal a cutoff frequency near 3 mHz, up to which the oscillations are evanescent, while those with higher frequencies propagate upward. The power-law index appears to increase with atmospheric height. Also, shorter damping lengths are observed for oscillations with higher frequencies suggesting frequency-dependent damping. Using the relative amplitudes of the 5.5 mHz (3 minute) oscillations, we estimate the energy flux at different heights, which seems to decay gradually from the photosphere, in agreement with recent numerical simulations. Furthermore, a comparison of power spectra across the umbral radius highlights an enhancement of high-frequency waves near the umbral center, which does not seem to be related to magnetic field inclination angle effects.

  19. Solar wind and coronal structure near sunspot minimum: Pioneer and SMM observations from 1985-1987

    International Nuclear Information System (INIS)

    Mihalov, J.D.; Barnes, A.; Hundhausen, A.J.; Smith, E.J.

    1990-01-01

    The solar wind speeds observed in the outer heliosphere (20 to 40 AU heliocentric distance, approximately) by Pioneers 10 an 11, and at a heliocentric distance of 0.7 AU by the Pioneer Venus spacecraft, reveal a complex set of changes in the years near the recent sunspot minimum, 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations made from the Solar Maximum Mission spacecraft during the same epoch show a systematic variation in coronal structure and (by implication) the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet (or with heliomagnetic latitude), and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum. The authors confirm here that this basic organization of the solar wind speed persists in the outer heliosphere with an orientation of the neutral sheet consistent with that inferred at a heliocentric distance of a few solar radii, from the coronal observations

  20. Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot

    Science.gov (United States)

    Henze, W., Jr.; Tandberg-Hanssen, E.; Hagyard, M. J.; West, E. A.; Woodgate, B. E.; Shine, R. A.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; West, E. A.

    1982-01-01

    The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arcsec and 3 arcsec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are compared from the two sets of data; the maximum gradients of 0.41 to 0.62 G/km occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.

  1. Sunspots and the physics of magnetic flux tubes. II. Aerodynamic drag

    International Nuclear Information System (INIS)

    Parker, E.N.

    1979-01-01

    The aerodynamic drag on a slender flux tube stretched vertically across a convective cell may push the flux tube into the updrafts or into the downdrafts, depending on the density stratification of the convecting fluid and the asymmetry of the fluid motions. The drag is approximately proportional to the local kinetic energy density, so the density stratification weights the drag in favor of the upper layers where the density is low, tending to push the vertical tube into the downdrafts. If, however, the horizontal motions in the convective cell are concentrated toward the bottom of the cell, they may dominate over the upper layers, pushing the tube into the updrafts. In the simple, idealized circumstance of a vertical tube extending across a fluid of uniform density in a convective cell that is symmetric about its midplane, the net aerodynamic drag vanishes in lowest order. The higher order contributions, including the deflection of the tube, then provide a nonvanishing force pushing the tube into a stable equilibrium midway between the updraft and the downdraft.It is pointed out that in the strongly stratified convective zone of the Sun, a downdraft herds flux tubes together into a cluster, while an updraft disperses them. To account for the observed strong cohesion of the cluster of flux tubes that make up a sunspot, we propose a downdraft of the order 2 km s - 1 through the cluster of seprate tubes beneath the sunspot

  2. The reconciliation of an F-region irregularity model with sunspot-cycle variations in spread-F occurrence

    International Nuclear Information System (INIS)

    Singleton, D.G.

    1974-11-01

    A recently proposed means of combining models of ionospheric F-layer peak electron density and irregularity incremental electron density (ΔN) so as to simulate the global occurrence probability of the frequency spreading component of spread-F is discussed. This procedure is then used to model experimental spread-F occurrence results. It is found possible to readily simulate the sunspot-maximum results, independently of season, with only small adjustments to the amplitudes of the empirical expressions used to ΔN in the several latitude regimes. However, at sunspot minimum and for each season, the ΔN model requires modification in the equatorial and mid-latitude regions of high irregularity incidence, before successful simulations of the spread-F data can be obtained. These modifications, which include a broadening of the equatorial region and a polewards shift to the mid-latitude region with decreasing sunspot number, are discussed in detail. It is concluded that the scintillation data base, from which the original ΔN model derives, is not sufficiently representative with regard to sunspot number and magnetic index. The use of the spread-F adaptation of the ΔN model, as well as its original scintillation version, to rectify these failings of the ΔN model are also discussed. (author)

  3. Effect of solar flare ans sunspot numbers on the intensity of 5577A line in the night airglow

    International Nuclear Information System (INIS)

    Kundu, N.; Ghosh, S.N.

    1981-01-01

    The effects of solar flare and sunspot number on the intensity of 5577 A line emission are presented. The time lag between the occurrence of a flare and the enhancement of 5577 A line intensity is determined by observing the intensity of the line on three successive nights- the night preceding the flare and the two nights following it. The velocity of the solar corpuscles is then calculated. The value obtained at Allahabad (2400 Km/sec) is in agreement with the De Jager's prediction for explosive flare. Day-to-day analyses of the observations taken at Allahabad exhibit high correlation of the intensity of 5577 A line emission with sunspot number. Also, correlation is found for the intensity of 5577 A with the change in sunspot number (DELTA R) from the day preceding the night of observation to the day following it. The intensity appears to vary with the magnetic field produced by the sunspot and not with the spot area. (author)

  4. Values of Kp Indices, Ap Indices, Cp Indices, C9 Indices, Sunspot Number, and 10.7 cm Flux

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data file consists of Kp indices, Ap indices, Cp indices, C9 indices, sunspot number, and 10.7 cm flux. The most often requested parameter of this file are the...

  5. Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987

    Science.gov (United States)

    Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J.

    1990-01-01

    Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum.

  6. Vector magnetic fields in sunspots. I - Stokes profile analysis using the Marshall Space Flight Center magnetograph

    Science.gov (United States)

    Balasubramaniam, K. S.; West, E. A.

    1991-01-01

    The Marshall Space Flight Center (MSFC) vector magnetograph is a tunable filter magnetograph with a bandpass of 125 mA. Results are presented of the inversion of Stokes polarization profiles observed with the MSFC vector magnetograph centered on a sunspot to recover the vector magnetic field parameters and thermodynamic parameters of the spectral line forming region using the Fe I 5250.2 A spectral line using a nonlinear least-squares fitting technique. As a preliminary investigation, it is also shown that the recovered thermodynamic parameters could be better understood if the fitted parameters like Doppler width, opacity ratio, and damping constant were broken down into more basic quantities like temperature, microturbulent velocity, or density parameter.

  7. Oscillations in sunspot umbras due to trapped Alfven waves excited by overstability

    International Nuclear Information System (INIS)

    Uchida, Yutaka; Sakurai, Takashi.

    1975-01-01

    Oscillations observed in sunspot umbras are interpreted as a vertical motion in the atmosphere induced by a standing Alfven wave trapped in the region between the overstable layer under the photosphere and the chromosphere-corona transition layer. The Alfven wave motion is considered to be excited by the overstable convection occurring at the bottom of the abovementioned oscillating layer, and waves with special frequencies are selected as eigen-mode waves standing in the ''cavity,'' while other waves which are out of phase with themselves after reflections will disappear. It is shown by solving the eigen-value problem that the fundamental eigen frequency falls in a range around 0.04 rad s -1 (corresponding to 140-180 s) for the condition in the umbra of a typical spot, and also that the eigen frequencies do not depend greatly on the circumstantial physical or geometric parameters of the model atmosphere, such as the temperature in the layer, or the height of the transition layer, etc. The eigen frequencies, however, depend on the Alfven velocity at the base of the oscillating layer (or at the top of the overstable layer), but the latter quantity, which represents the stiffness of the magnetic tube of force against the overturning motion, takes roughly a common value for different sunspots according to SAVAGE's (1969) stability analysis of the umbral atmosphere against thermal convection, and thus gives a comparatively narrow range of resonant frequencies. In addition to the selection mechanism for oscillations of 140-180-s period, some other aspects of the oscillation, such as the relation to the running penumbral waves, are discussed. (auth.)

  8. Surge-like Oscillations above Sunspot Light Bridges Driven by Magnetoacoustic Shocks

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingwen; Tian, Hui; He, Jiansen; Wang, Linghua, E-mail: huitian@pku.edu.cn [School of Earth and Space Sciences, Peking University, 100871 Beijing (China)

    2017-03-20

    High-resolution observations of the solar chromosphere and transition region often reveal surge-like oscillatory activities above sunspot light bridges (LBs). These oscillations are often interpreted as intermittent plasma jets produced by quasi-periodic magnetic reconnection. We have analyzed the oscillations above an LB in a sunspot using data taken by the Interface Region Imaging Spectrograph . The chromospheric 2796 Å images show surge-like activities above the entire LB at any time, forming an oscillating wall. Within the wall we often see that the core of the Mg ii k 2796.35 Å line first experiences a large blueshift, and then gradually decreases to zero shift before increasing to a redshift of comparable magnitude. Such a behavior suggests that the oscillations are highly nonlinear and likely related to shocks. In the 1400 Å passband, which samples emission mainly from the Si iv ion, the most prominent feature is a bright oscillatory front ahead of the surges. We find a positive correlation between the acceleration and maximum velocity of the moving front, which is consistent with numerical simulations of upward propagating slow-mode shock waves. The Si iv 1402.77 Å line profile is generally enhanced and broadened in the bright front, which might be caused by turbulence generated through compression or by the shocks. These results, together with the fact that the oscillation period stays almost unchanged over a long duration, lead us to propose that the surge-like oscillations above LBs are caused by shocked p-mode waves leaked from the underlying photosphere.

  9. THE MYSTERIOUS CASE OF THE SOLAR ARGON ABUNDANCE NEAR SUNSPOTS IN FLARES

    International Nuclear Information System (INIS)

    Doschek, G. A.; Warren, H. P.

    2016-01-01

    Recently we discussed an enhancement of the abundance of Ar xiv relative to Ca xiv near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The observed Ar xiv/Ca xiv ratio yields an argon/calcium abundance ratio seven times greater than expected from the photospheric abundance. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as being due to an inverse first ionization potential (FIP) effect. In the published work, two lines of Ar xiv were observed, and one line was tentatively identified as an Ar xi line. In this paper, we report observing a similar enhancement in a full-CCD EIS flare spectrum in 13 argon lines that lie within the EIS wavelength ranges. The observed lines include two Ar xi lines, four Ar xiii lines, six Ar xiv lines, and one Ar xv line. The enhancement is far less than reported in Doschek et al. but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and the abundance could be photospheric. This enhancement occurs in association with a sunspot in a small area only a few arcseconds (1″ = about 700 km) in size. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. indicate a depletion of low-FIP elements.

  10. NUMERICAL SIMULATIONS OF CONVERSION TO ALFVÉN WAVES IN SUNSPOTS

    International Nuclear Information System (INIS)

    Khomenko, E.; Cally, P. S.

    2012-01-01

    We study the conversion of fast magnetoacoustic waves to Alfvén waves by means of 2.5D numerical simulations in a sunspot-like magnetic configuration. A fast, essentially acoustic, wave of a given frequency and wave number is generated below the surface and propagates upward through the Alfvén/acoustic equipartition layer where it splits into upgoing slow (acoustic) and fast (magnetic) waves. The fast wave quickly reflects off the steep Alfvén speed gradient, but around and above this reflection height it partially converts to Alfvén waves, depending on the local relative inclinations of the background magnetic field and the wavevector. To measure the efficiency of this conversion to Alfvén waves we calculate acoustic and magnetic energy fluxes. The particular amplitude and phase relations between the magnetic field and velocity oscillations help us to demonstrate that the waves produced are indeed Alfvén waves. We find that the conversion to Alfvén waves is particularly important for strongly inclined fields like those existing in sunspot penumbrae. Equally important is the magnetic field orientation with respect to the vertical plane of wave propagation, which we refer to as 'field azimuth'. For a field azimuth less than 90° the generated Alfvén waves continue upward, but above 90° downgoing Alfvén waves are preferentially produced. This yields negative Alfvén energy flux for azimuths between 90° and 180°. Alfvén energy fluxes may be comparable to or exceed acoustic fluxes, depending upon geometry, though computational exigencies limit their magnitude in our simulations.

  11. Emergence of Magnetic Flux Generated in a Solar Convective Dynamo. I. The Formation of Sunspots and Active Regions, and The Origin of Their Asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Feng; Rempel, Matthias; Fan, Yuhong, E-mail: chenfeng@ucar.edu [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO, 80307 (United States)

    2017-09-10

    We present a realistic numerical model of sunspot and active region formation based on the emergence of flux bundles generated in a solar convective dynamo. To this end, we use the magnetic and velocity fields in a horizontal layer near the top boundary of the solar convective dynamo simulation to drive realistic radiative-magnetohydrodynamic simulations of the uppermost layers of the convection zone. The main results are as follows. (1) The emerging flux bundles rise with the mean speed of convective upflows and fragment into small-scale magnetic elements that further rise to the photosphere, where bipolar sunspot pairs are formed through the coalescence of the small-scale magnetic elements. (2) Filamentary penumbral structures form when the sunspot is still growing through ongoing flux emergence. In contrast to the classical Evershed effect, the inflow seems to prevail over the outflow in a large part of the penumbra. (3) A well-formed sunspot is a mostly monolithic magnetic structure that is anchored in a persistent deep-seated downdraft lane. The flow field outside the spot shows a giant vortex ring that comprises an inflow below 15 Mm depth and an outflow above 15 Mm depth. (4) The sunspots successfully reproduce the fundamental properties of the observed solar active regions, including the more coherent leading spots with a stronger field strength, and the correct tilts of bipolar sunspot pairs. These asymmetries can be linked to the intrinsic asymmetries in the magnetic and flow fields adapted from the convective dynamo simulation.

  12. CHROMOSPHERIC MASS MOTIONS AND INTRINSIC SUNSPOT ROTATIONS FOR NOAA ACTIVE REGIONS 10484, 10486, AND 10488 USING ISOON DATA

    International Nuclear Information System (INIS)

    Hardersen, Paul S.; Balasubramaniam, K. S.; Shkolyar, Svetlana

    2013-01-01

    This work utilizes Improved Solar Observing Optical Network continuum (630.2 nm) and Hα (656.2 nm) data to: (1) detect and measure intrinsic sunspot rotations occurring in the photosphere and chromosphere, (2) identify and measure chromospheric filament mass motions, and (3) assess any large-scale photospheric and chromospheric mass couplings. Significant results from 2003 October 27-29, using the techniques of Brown et al., indicate significant counter-rotation between the two large sunspots in NOAA AR 10486 on October 29, as well as discrete filament mass motions in NOAA AR 10484 on October 27 that appear to be associated with at least one C-class solar flare

  13. Influence of the sunspot cycle on the Northern Hemisphere wintertime circulation from long upper-air data sets

    Directory of Open Access Journals (Sweden)

    Y. Brugnara

    2013-07-01

    Full Text Available Here we present a study of the 11 yr sunspot cycle's imprint on the Northern Hemisphere atmospheric circulation, using three recently developed gridded upper-air data sets that extend back to the early twentieth century. We find a robust response of the tropospheric late-wintertime circulation to the sunspot cycle, independent from the data set. This response is particularly significant over Europe, although results show that it is not directly related to a North Atlantic Oscillation (NAO modulation; instead, it reveals a significant connection to the more meridional Eurasian pattern (EU. The magnitude of mean seasonal temperature changes over the European land areas locally exceeds 1 K in the lower troposphere over a sunspot cycle. We also analyse surface data to address the question whether the solar signal over Europe is temporally stable for a longer 250 yr period. The results increase our confidence in the existence of an influence of the 11 yr cycle on the European climate, but the signal is much weaker in the first half of the period compared to the second half. The last solar minimum (2005 to 2010, which was not included in our analysis, shows anomalies that are consistent with our statistical results for earlier solar minima.

  14. Successive X-class Flares and Coronal Mass Ejections Driven by Shearing Motion and Sunspot Rotation in Active Region NOAA 12673

    Science.gov (United States)

    Yan, X. L.; Wang, J. C.; Pan, G. M.; Kong, D. F.; Xue, Z. K.; Yang, L. H.; Li, Q. L.; Feng, X. S.

    2018-03-01

    We present a clear case study on the occurrence of two successive X-class flares, including a decade-class flare (X9.3) and two coronal mass ejections (CMEs) triggered by shearing motion and sunspot rotation in active region NOAA 12673 on 2017 September 6. A shearing motion between the main sunspots with opposite polarities began on September 5 and lasted even after the second X-class flare on September 6. Moreover, the main sunspot with negative polarity rotated around its umbral center, and another main sunspot with positive polarity also exhibited a slow rotation. The sunspot with negative polarity at the northwest of the active region also began to rotate counterclockwise before the onset of the first X-class flare, which is related to the formation of the second S-shaped structure. The successive formation and eruption of two S-shaped structures were closely related to the counterclockwise rotation of the three sunspots. The existence of a flux rope is found prior to the onset of two flares by using nonlinear force-free field extrapolation based on the vector magnetograms observed by Solar Dynamics Observatory/Helioseismic and Magnetic Image. The first flux rope corresponds to the first S-shaped structures mentioned above. The second S-shaped structure was formed after the eruption of the first flux rope. These results suggest that a shearing motion and sunspot rotation play an important role in the buildup of the free energy and the formation of flux ropes in the corona that produces solar flares and CMEs.

  15. INTERFERENCE OF THE RUNNING WAVES AT LIGHT BRIDGES OF A SUNSPOT

    Energy Technology Data Exchange (ETDEWEB)

    Su, J. T.; Priya, T. G.; Yu, S. J.; Zhang, M. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ji, K. F. [Kunming University of Science and Technology, Kunming 650093 (China); Banerjee, D. [Indian Institute of Astrophysics, Koramangala Bangalore 560034 (India); Cao, W. D. [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Zhao, J. S.; Ji, H. S., E-mail: jt@bao.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

    2016-01-01

    The observations of chromospheric oscillations of two umbral light bridges (LBs) within a sunspot from NOAA Active Region 12127 are presented. It was found that the running umbral waves with periods of 2.2–2.6 minutes underwent very fast damping before approaching umbral boundaries, while those with higher periods (>2.6 minutes) could propagate outside umbrae. On two sides of each LB adjacent to umbrae, the cross-wavelet spectra displayed that the oscillations on them had a common significant power region with dominant frequencies of 2–6 minutes and phase differences of ∼90°. A counterstream of two running umbral waves in the 2–6 minute frequency range propagated toward the LBs, where they encountered each other and gave rise to constructive or even destructive interference on the LBs. In addition, the velocity and density perturbations on the LBs were found in opposite phases suggesting that the perturbations were caused by the downward propagating waves.

  16. Principal components and iterative regression analysis of geophysical series: Application to Sunspot number (1750 2004)

    Science.gov (United States)

    Nordemann, D. J. R.; Rigozo, N. R.; de Souza Echer, M. P.; Echer, E.

    2008-11-01

    We present here an implementation of a least squares iterative regression method applied to the sine functions embedded in the principal components extracted from geophysical time series. This method seems to represent a useful improvement for the non-stationary time series periodicity quantitative analysis. The principal components determination followed by the least squares iterative regression method was implemented in an algorithm written in the Scilab (2006) language. The main result of the method is to obtain the set of sine functions embedded in the series analyzed in decreasing order of significance, from the most important ones, likely to represent the physical processes involved in the generation of the series, to the less important ones that represent noise components. Taking into account the need of a deeper knowledge of the Sun's past history and its implication to global climate change, the method was applied to the Sunspot Number series (1750-2004). With the threshold and parameter values used here, the application of the method leads to a total of 441 explicit sine functions, among which 65 were considered as being significant and were used for a reconstruction that gave a normalized mean squared error of 0.146.

  17. DETECTION OF SUPERSONIC DOWNFLOWS AND ASSOCIATED HEATING EVENTS IN THE TRANSITION REGION ABOVE SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Kleint, L.; Martínez-Sykora, J. [Bay Area Environmental Research Institute, 625 2nd Street, Ste. 209, Petaluma, CA (United States); Antolin, P. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tian, H.; Testa, P.; Reeves, K. K.; McKillop, S.; Saar, S.; Golub, L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Judge, P. [High Altitude Observatory/NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); De Pontieu, B.; Wuelser, J. P.; Boerner, P.; Hurlburt, N.; Lemen, J.; Tarbell, T. D.; Title, A. [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover St., Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States); Carlsson, M.; Hansteen, V. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Jaeggli, S., E-mail: lucia.kleint@fhnw.ch [Department of Physics, Montana State University, Bozeman, P.O. Box 173840, Bozeman, MT 59717 (United States); and others

    2014-07-10

    Interface Region Imaging Spectrograph data allow us to study the solar transition region (TR) with an unprecedented spatial resolution of 0.''33. On 2013 August 30, we observed bursts of high Doppler shifts suggesting strong supersonic downflows of up to 200 km s{sup –1} and weaker, slightly slower upflows in the spectral lines Mg II h and k, C II 1336, Si IV 1394 Å, and 1403 Å, that are correlated with brightenings in the slitjaw images (SJIs). The bursty behavior lasts throughout the 2 hr observation, with average burst durations of about 20 s. The locations of these short-lived events appear to be the umbral and penumbral footpoints of EUV loops. Fast apparent downflows are observed along these loops in the SJIs and in the Atmospheric Imaging Assembly, suggesting that the loops are thermally unstable. We interpret the observations as cool material falling from coronal heights, and especially coronal rain produced along the thermally unstable loops, which leads to an increase of intensity at the loop footpoints, probably indicating an increase of density and temperature in the TR. The rain speeds are on the higher end of previously reported speeds for this phenomenon, and possibly higher than the free-fall velocity along the loops. On other observing days, similar bright dots are sometimes aligned into ribbons, resembling small flare ribbons. These observations provide a first insight into small-scale heating events in sunspots in the TR.

  18. EVIDENCE FOR A TRANSITION REGION RESPONSE TO PENUMBRAL MICROJETS IN SUNSPOTS

    International Nuclear Information System (INIS)

    Vissers, G. J. M.; Rouppe van der Voort, L. H. M.; Carlsson, M.

    2015-01-01

    Penumbral microjets (PMJs) are short-lived, fine-structured, and bright jets that are generally observed in chromospheric imaging of the penumbra of sunspots. Here we investigate their potential transition region signature by combining observations with the Swedish 1-m Solar Telescope in the Ca ii H and Ca ii 8542 Å lines with ultraviolet imaging and spectroscopy obtained with the Interface Region Imaging Spectrograph (IRIS), which includes the C ii 1334/1335 Å, Si iv 1394/1403 Å, and Mg ii h and k 2803/2796 Å lines. We find a clear corresponding signal in the IRIS Mg ii k, C ii, and Si iv slit-jaw images, typically offset spatially from the Ca ii signature in the direction along the jets: from base to top, the PMJs are predominantly visible in Ca ii, Mg ii k, and C ii/Si iv, suggesting progressive heating to transition region temperatures along the jet extent. Hence, these results support the suggestion from earlier studies that PMJs may heat to transition region temperatures

  19. Fan-shaped jets above the light bridge of a sunspot driven by reconnection

    Science.gov (United States)

    Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodriguez, Jaime; Rouppe van der Voort, Luc

    2016-05-01

    We report on a fan-shaped set of high-speed jets above a strongly magnetized light bridge (LB) of a sunspot observed in the Hα line. We study the origin, dynamics, and thermal properties of the jets using high-resolution imaging spectroscopy in Hα from the Swedish 1m Solar Telescope and data from the Solar Dynamics Observatory and Hinode. The Hα jets have lengths of 7-38 Mm, are impulsively accelerated to a speed of ~100 km s-1 close to photospheric footpoints in the LB, and exhibit a constant deceleration consistent with solar effective gravity. They are predominantly launched from one edge of the light bridge, and their footpoints appear bright in the Hα wings. Atmospheric Imaging Assembly data indicates elongated brightenings that are nearly co-spatial with the Hα jets. We interpret them as jets of transition region temperatures. The magnetic field in the light bridge has a strength of 0.8-2 kG and it is nearly horizontal. All jet properties are consistent with magnetic reconnection as the driver. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

  20. A steady-state supersonic downflow in the transition region above a sunspot umbra

    Science.gov (United States)

    Straus, Thomas; Fleck, Bernhard; Andretta, Vincenzo

    2015-10-01

    We investigate a small-scale (~1.5 Mm along the slit), supersonic downflow of about 90 km s-1 in the transition region above the lightbridged sunspot umbra in AR 11836. The observations were obtained with the Interface Region Spectrograph (IRIS) on 2013 September 2 from 16:40 to 17:59 UT. The downflow shows up as redshifted "satellite" lines of the Si iv and O iv transition region lines and is remarkably steady over the observing period of nearly 80 min. The downflow is not visible in the chromospheric lines, which only show an intensity enhancement at the location of the downflow. The density inferred from the line ratio of the redshifted satellites of the O iv lines (Ne = 1010.6 ± 0.25 cm-3) is only a factor 2 smaller than the one inferred from the main components (Ne = 1010.95 ± 0.20 cm-3). Consequently, this implies a substantial mass flux (~5 × 10-7 g cm-2 s-1), which would evacuate the overlying corona on timescales close to 10 s. We interpret these findings as evidence of a stationary termination shock of a supersonic siphon flow in a cool loop that is rooted in the central umbra of the spot. The movie is available in electronic form at http://www.aanda.org

  1. Complex network approach to characterize the statistical features of the sunspot series

    International Nuclear Information System (INIS)

    Zou, Yong; Liu, Zonghua; Small, Michael; Kurths, Jürgen

    2014-01-01

    Complex network approaches have been recently developed as an alternative framework to study the statistical features of time-series data. We perform a visibility-graph analysis on both the daily and monthly sunspot series. Based on the data, we propose two ways to construct the network: one is from the original observable measurements and the other is from a negative-inverse-transformed series. The degree distribution of the derived networks for the strong maxima has clear non-Gaussian properties, while the degree distribution for minima is bimodal. The long-term variation of the cycles is reflected by hubs in the network that span relatively large time intervals. Based on standard network structural measures, we propose to characterize the long-term correlations by waiting times between two subsequent events. The persistence range of the solar cycles has been identified over 15–1000 days by a power-law regime with scaling exponent γ = 2.04 of the occurrence time of two subsequent strong minima. In contrast, a persistent trend is not present in the maximal numbers, although maxima do have significant deviations from an exponential form. Our results suggest some new insights for evaluating existing models. (paper)

  2. Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration Missions

    Science.gov (United States)

    Atwell, William; Tylka, Allan J.; Dietrich, William F.; Rojdev, Kristina; Matzkind, Courtney

    2016-01-01

    In an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.

  3. Simultaneous Observations of p-mode Light Walls and Magnetic Reconnection Ejections above Sunspot Light Bridges

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Xiaohong, E-mail: yijunhou@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2017-10-10

    Recent high-resolution observations from the Interface Region Imaging Spectrograph reveal bright wall-shaped structures in active regions (ARs), especially above sunspot light bridges. Their most prominent feature is the bright oscillating front in the 1400/1330 Å channel. These structures are named light walls and are often interpreted to be driven by p-mode waves. Above the light bridge of AR 12222 on 2014 December 06, we observed intermittent ejections superimposed on an oscillating light wall in the 1400 Å passband. At the base location of each ejection, the emission enhancement was detected in the Solar Dynamics Observatory 1600 Å channel. Thus, we suggest that in wall bases (light bridges), in addition to the leaked p-mode waves consistently driving the oscillating light wall, magnetic reconnection could happen intermittently at some locations and eject the heated plasma upward. Similarly, in the second event occurring in AR 12371 on 2015 June 16, a jet was simultaneously detected in addition to the light wall with a wave-shaped bright front above the light bridge. At the footpoint of this jet, lasting brightening was observed, implying magnetic reconnection at the base. We propose that in these events, two mechanisms, p-mode waves and magnetic reconnection, simultaneously play roles in the light bridge, and lead to the distinct kinetic features of the light walls and the ejection-like activities, respectively. To illustrate the two mechanisms and their resulting activities above light bridges, in this study we present a cartoon model.

  4. On the structure of a magnetic field and its evolution in the vicinity of sunspots

    International Nuclear Information System (INIS)

    Gopasyuk, S.I.; Kartashova, L.G.

    1981-01-01

    The structure of magnetic field and its evolution around single large sunspots has been studied. For this purpose observational data of the longitudinal magnetic field on the photospheric level and hsub(α) filtergrams for 18 active regions have been used. It is shown that there are characteristic directions corresponding to the transition of the spot field without sign change into an extended region of the same polarity and coinciding with extended (100000-300000 km) systems of filamentary feature chains of the fine chromospheric structure in active region. The horizontal magnetic f+eld component of the spot (systems of filamentary feature chains of the fine chromospheric structure) disappears on an extended region of chromospheric surface in the direction, where the satellite field (the field of opposite polarity) appears near its boundary. On the other hand, when satellite field disappears at some direction from the spot the transversal magnetic field appears on the extended surface region of the chromosphere keeping the same direction. One of the possible causes of disappearance of the transversal magnetic field on an extended region in the chromosphere might be the reconnection of magnetic lines of force [ru

  5. The Earth's Interaction With the Sun Over the Millennia From Analyses of Historical Sunspot, Auroral and Climate Records

    Science.gov (United States)

    Yau, K.

    2001-12-01

    A prolonged decrease in the Sun's irradiance during the Maunder Minimum has been proposed as a cause of the Little Ice Age ({ca} 1600-1800). Eddy [{Science} {192}, 1976, 1189] made this suggestion after noting that very few sunspots were observed from 1645 to 1715, indicative of a weakened Sun. Pre-telescopic Oriental sunspot records go back over 2200 years. Periods when no sunspots were seen have been documented by, {eg}, Clark [{Astron} {7}, 2/1979, 50]. Abundances of C 14 in tree rings and Be10 in ice cores are also good indicators of past solar activity. These isotopes are produced by cosmic rays high in the atmosphere. When the Sun is less active more of them are made and deposited at ground level. There is thus a strong {negative} correlation between their abundances and sunspot counts. Minima of solar activity in tree rings and a south polar ice core have been collated by, {eg}, Bard [{Earth Planet Sci Lett} {150} 1997, 453]; and show striking correspondence with periods when no sunspots were seen, centered at {ca} 900, 1050, 1500, 1700. Pang and Yau [{Eos} {79}, #45, 1998, F149] investigated the Medieval Minimum at 700, using in addition the frequency of auroral sighting7s, a good indicator of solar activity too [Yau, PhD thesis, 1988]; and found that the progression of minima in solar activity goes back to 700. Auroral frequency, C 14 and Be 10 concentrations are also affected by variations in the geomagnetic field. Deposition changes can also influence C 14 and Be 10 abundances. Sunspot counts are thus the only true indicator of solar activity. The Sun's bolometric variations (-0.3% for the Maunder Minimum) can contribute to climatic changes (\\0.5° C for the Little Ice Age)[{eg}, Lean, {GRL} {22}, 1995, 3195]. For times with no thermometer data, temperature can be estimated from, {eg}, Oxygen 18 isotopic abundance in ice cores, which in turn depends on the temperature of the ocean water it evaporated from. We have linked the Medieval Minimum to the cold

  6. Worldwide variation in atmospheric noise intensities with sunspot number: an in-depth look at the 20 to 24 hour seasonal time block

    International Nuclear Information System (INIS)

    Joglekar, P.J.; Sathiamurthy, T.S.

    1975-01-01

    Comparisons of the variation of atmospheric radio noise intensities for 20 to 24 hr to sunspot numbers have been completed. Statistical dependence between the noise intensities and sunspot numbers was found for different seasons at a number of frequencies for many locations in the global network of ARN-2 noise recorders. The noise intensities generally tended to decrease with sunspot number in the range from 50 kHz to 5 MHz, which is presumed to be due to increases in residual ionospheric absorption during nighttime. At frequencies greater than 5 MHz, noise intensities increased with sunspot number in many cases, which would be expected from our present knowledge of ionospheric behavior in the HF range. By convention, CCIR treats year-to-year variation in the noise intensities as random and includes them in the prediction uncertainty sigma /sub Fam/ (for which one value is given at a frequency for a seasonal time block for all locations) in system performance evaluation. An error analysis on a global basis shows that a large portion of the year-to-year variability is due to sunspot variation. This suggests the possibility of improved noise estimates. (auth)

  7. Extending Counter-streaming Motion from an Active Region Filament to a Sunspot Light Bridge

    Science.gov (United States)

    Wang, Haimin; Liu, Rui; Li, Qin; Liu, Chang; Deng, Na; Xu, Yan; Jing, Ju; Wang, Yuming; Cao, Wenda

    2018-01-01

    We analyze high-resolution observations from the 1.6 m telescope at Big Bear Solar Observatory that cover an active region filament. Counter-streaming motions are clearly observed in the filament. The northern end of the counter-streaming motions extends to a light bridge, forming a spectacular circulation pattern around a sunspot, with clockwise motion in the blue wing and counterclockwise motion in the red wing, as observed in the Hα off-bands. The apparent speed of the flow is around 10–60 km s‑1 in the filament, decreasing to 5–20 km s‑1 in the light bridge. The most intriguing results are the magnetic structure and the counter-streaming motions in the light bridge. Similar to those in the filament, the magnetic fields show a dominant transverse component in the light bridge. However, the filament is located between opposed magnetic polarities, while the light bridge is between strong fields of the same polarity. We analyze the power of oscillations with the image sequences of constructed Dopplergrams, and find that the filament’s counter-streaming motion is due to physical mass motion along fibrils, while the light bridge’s counter-streaming motion is due to oscillation in the direction along the line-of-sight. The oscillation power peaks around 4 minutes. However, the section of the light bridge next to the filament also contains a component of the extension of the filament in combination with the oscillation, indicating that some strands of the filament are extended to and rooted in that part of the light bridge.

  8. SOLAR VARIABILITY FROM 240 TO 1750 nm IN TERMS OF FACULAE BRIGHTENING AND SUNSPOT DARKENING FROM SCIAMACHY

    International Nuclear Information System (INIS)

    Pagaran, J.; Weber, M.; Burrows, J.

    2009-01-01

    The change of spectral decomposition of the total radiative output on various timescales of solar magnetic activity is of large interest to terrestrial and solar-stellar atmosphere studies. Starting in 2002, SCIAMACHY was the first satellite instrument to observe daily solar spectral irradiance (SSI) continuously from 230 nm (UV) to 1750 nm (near-infrared; near-IR). In order to address the question of how much UV, visible (vis), and IR spectral regions change on 27 day and 11 year timescales, we parameterize short-term SSI variations in terms of faculae brightening (Mg II index) and sunspot darkening (photometric sunspot index) proxies. Although spectral variations above 300 nm are below 1% and, therefore, well below the accuracy of absolute radiometric calibration, relative accuracy for short-term changes is shown to be in the per mill range. This enables us to derive short-term spectral irradiance variations from the UV to the near-IR. During Halloween solar storm in 2003 with a record high sunspot area, we observe a reduction of 0.3% in the near-IR to 0.5% in the vis and near-UV. This is consistent with a 0.4% reduction in total solar irradiance (TSI). Over an entire 11 year solar cycle, SSI variability covering simultaneously the UV, vis, and IR spectral regions have not been directly observed so far. Using variations of solar proxies over solar cycle 23, solar cycle spectral variations have been estimated using scaling factors that best matched short-term variations of SCIAMACHY. In the 300-400 nm region, which strongly contributes to TSI solar cycle change, a contribution of 34% is derived from SCIAMACHY observations, which is lower than the reported values from SUSIM satellite data and the empirical SATIRE model. The total UV contribution (below 400 nm) to TSI solar cycle variations is estimated to be 55%.

  9. A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1986-01-01

    Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  10. A dynamo theory prediction for solar cycle 22 - Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1984-01-01

    Using the 'dynamo theory' method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  11. Period of sunspot numbers is 11.02653720 years (11 years 9 days 16 hours 18 minutes 0 seconds)

    International Nuclear Information System (INIS)

    Norita, Sadataka

    1976-01-01

    In the statistical analysis of time series there have been applied usually the stationary stochastic process or the Markov stochastic process and recently there are applied remarkably an autoregressive process, a stochastic difference equation, an autoregressive-moving average process, a moving average process, the Whittaker periodogram, the correlogram, Schuster periodogram, chi-squared periodogram, level crossings, harmonic process, difference method, spectral density and first order vector equation, but in special case it is desirable to apply the nonstationary stocastic process. In this paper we introduce an stationarity into the autoregressive process and then it is the first purpose to compute precisely period of sunspot numbers. The result up to the eighth places at the decimal point was obtained that its period is 11.02653720 years, that is, 11 years 9 days 16 hours 18 minutes 0 seconds. This is considered to be more relevant than numerical values by which Schuster (1906) and Yule (1927) had calculated the respective 11.125 years and 10.60 years in the past. We revised the theoretical expression in the thesis of Anderson, Shaman, Lindgren, Brillinger, Newbold, Parzen, Kingman, Van Ness and Kenneth, etc. and executed the numerical analysis of period of sunspot numbers investigated now. (auth.)

  12. Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

    Science.gov (United States)

    Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

    1988-01-01

    The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

  13. Determination of the Alfvén Speed and Plasma-beta Using the Seismology of Sunspot Umbra

    Energy Technology Data Exchange (ETDEWEB)

    Cho, I.-H.; Moon, Y.-J.; Nakariakov, V. M.; Park, J.; Choi, S. [Department of Astronomy and Space Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Cho, K.-S.; Bong, S.-C.; Baek, J.-H.; Kim, Y.-H.; Lee, J., E-mail: ihjo@khu.ac.kr [Space Science Division, Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

    2017-03-01

    For 478 centrally located sunspots observed in the optical continuum with Solar Dynamics Observatory /Helioseismic Magnetic Imager, we perform seismological diagnostics of the physical parameters of umbral photospheres. The new technique is based on the theory of slow magnetoacoustic waves in a non-isothermally stratified photosphere with a uniform vertical magnetic field. We construct a map of the weighted frequency of three-minute oscillations inside the umbra and use it for the estimation of the Alfvén speed, plasma-beta, and mass density within the umbra. We find the umbral mean Alfvén speed ranges between 10.5 and 7.5 km s{sup −1} and is negatively correlated with magnetic field strength. The umbral mean plasma-beta is found to range approximately between 0.65 and 1.15 and does not vary significantly from pores to mature sunspots. The mean density ranges between (1–6) × 10{sup −4} kg m{sup −3} and shows a strong positive correlation with magnetic field strength.

  14. Period of sunspot numbers is 11. 02653720 years (11 years 9 days 16 hours 18 minutes 0 seconds)

    Energy Technology Data Exchange (ETDEWEB)

    Norita, S [Miyazaki Univ. (Japan). Faculty of Engineering

    1976-09-01

    In the statistical analysis of time series there have been applied usually the stationary stochastic process or the Markov stochastic process and recently there are applied remarkably an autoregressive process, a stochastic difference equation, an autoregressive-moving average process, a moving average process, the Whittaker periodogram, the correlogram, Schuster periodogram, chi-squared periodogram, level crossings, harmonic process, difference method, spectral density and first order vector equation, but in special case it is desirable to apply the nonstationary stocastic process. In this paper we introduce a stationarity into the autoregressive process and then it is the first purpose to compute precisely the period of sunspot numbers. The result up to the eighth places at the decimal point was obtained that its period is 11.02653720 years, that is, 11 years 9 days 16 hours 18 minutes 0 seconds. This is considered to be more relevant than numerical values by which Schuster (1906) and Yule (1927) had calculated the respective 11.125 years and 10.60 years in the past. We revised the theoretical expression in the thesis of Anderson, Shaman, Lindgren, Brillinger, Newbold, Parzen, Kingman, Van Ness and Kenneth, etc. and executed the numerical analysis of period of sunspot numbers investigated now.

  15. Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-Flaring Active Regions

    Science.gov (United States)

    Kilcik, A.; Yurchyshyn, V.; Donmez, B.; Obridko, V. N.; Ozguc, A.; Rozelot, J. P.

    2018-04-01

    We analyzed temporal and periodic variations of sunspot counts (SSCs) in flaring (C-, M-, or X-class flares), and non-flaring active regions (ARs) for nearly three solar cycles (1986 through 2016). Our main findings are as follows: i) temporal variations of monthly means of the daily total SSCs in flaring and non-flaring ARs behave differently during a solar cycle and the behavior varies from one cycle to another; during Solar Cycle 23 temporal SSC profiles of non-flaring ARs are wider than those of flaring ARs, while they are almost the same during Solar Cycle 22 and the current Cycle 24. The SSC profiles show a multi-peak structure and the second peak of flaring ARs dominates the current Cycle 24, while the difference between peaks is less pronounced during Solar Cycles 22 and 23. The first and second SSC peaks of non-flaring ARs have comparable magnitude in the current solar cycle, while the first peak is nearly absent in the case of the flaring ARs of the same cycle. ii) Periodic variations observed in the SSCs profiles of flaring and non-flaring ARs derived from the multi-taper method (MTM) spectrum and wavelet scalograms are quite different as well, and they vary from one solar cycle to another. The largest detected period in flaring ARs is 113± 1.6 days while we detected much longer periodicities (327± 13, 312 ± 11, and 256± 8 days) in the non-flaring AR profiles. No meaningful periodicities were detected in the MTM spectrum of flaring ARs exceeding 55± 0.7 days during Solar Cycles 22 and 24, while a 113± 1.3 days period was detected in flaring ARs of Solar Cycle 23. For the non-flaring ARs the largest detected period was only 31± 0.2 days for Cycle 22 and 72± 1.3 days for the current Cycle 24, while the largest measured period was 327± 13 days during Solar Cycle 23.

  16. Normal and counter Evershed flows in the photospheric penumbra of a sunspot SPINOR 2D inversions of Hinode-SOT/SP observations

    Czech Academy of Sciences Publication Activity Database

    Siu-Tapia, A.; Lagg, A.; Solanki, S.K.; van Noort, M.; Jurčák, Jan

    2017-01-01

    Roč. 607, November (2017), A36/1-A36/17 E-ISSN 1432-0746 Institutional support: RVO:67985815 Keywords : sunspots * photosphere * magnetic fields Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

  17. HIGH RESOLUTION He i 10830 Å NARROW-BAND IMAGING OF AN M-CLASS FLARE. I. ANALYSIS OF SUNSPOT DYNAMICS DURING FLARING

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ya; Su, Yingna; Hong, Zhenxiang; Ji, Haisheng [Key Laboratory of DMSA, Purple Mountain Observatory, CAS, Nanjing, 210008 (China); Zeng, Zhicheng; Goode, Philip R.; Cao, Wenda [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Ji, Kaifan [Yunnan Astronomical Observatories, Kunming 650011 (China)

    2016-12-20

    In this paper, we report our first-step results of high resolution He i 10830 Å narrow-band imaging (bandpass: 0.5 Å) of an M1.8 class two-ribbon flare on 2012 July 5. The flare was observed with the 1.6 m aperture New Solar Telescope at Big Bear Solar Observatory. For this unique data set, sunspot dynamics during flaring were analyzed for the first time. By directly imaging the upper chromosphere, running penumbral waves are clearly seen as an outward extension of umbral flashes; both take the form of absorption in the 10830 Å narrow-band images. From a space–time image made of a slit cutting across a flare ribbon and the sunspot, we find that the dark lanes for umbral flashes and penumbral waves are obviously broadened after the flare. The most prominent feature is the sudden appearance of an oscillating absorption strip inside the ribbon when it sweeps into the sunspot’s penumbral and umbral regions. During each oscillation, outwardly propagating umbral flashes and subsequent penumbral waves rush out into the inwardly sweeping ribbon, followed by a return of the absorption strip with similar speed. We tentatively explain the phenomena as the result of a sudden increase in the density of ortho-helium atoms in the area of the sunspot being excited by the flare’s extreme ultraviolet illumination. This explanation is based on the observation that 10830 Å absorption around the sunspot area gets enhanced during the flare. Nevertheless, questions are still open and we need further well-devised observations to investigate the behavior of sunspot dynamics during flares.

  18. Open-ended and Open-door Treatment Groups for Young People with Mental Illness.

    Science.gov (United States)

    Miller, Rachel; Mason, Susan E

    2012-01-01

    The concept of open-ended groups is expanded to include an open-door model (OEOD) wherein members with severe mental illnesses, including schizophrenia disorders and bi-polar, can join, leave, and re-enter groups as their life circumstances dictate their availability and willingness for treatment. This model is grounded on the work of Schopler and Galinsky's (1984/2006) and Galinsky and Schopler's (1989) theses on the value and processes of open-ended groups and includes perspectives on mutual aid and group development. Groupwork with the OEOD format is illustrated with examples taken from a group of 79 participants diagnosed with first-episode schizophrenia/schizoaffective disorders, 40 of who had co-occurring substance abuse. Of the 79 participants in the OEOD group program, 70 (89%) remained in treatment for the maximum of 3 years. The over-all value of group treatment for this population is reviewed along with the small number of available publications on open-ended and open-door-type groups.

  19. Stokes profile analysis and vector magnetic fields. III. Extended temperature minima of sunspot umbrae as inferred from Stokes profiles of Mg I 4571 A

    International Nuclear Information System (INIS)

    Lites, B.W.; Skumanich, A.; Rees, D.E.; Murphy, G.A.; Carlsson, M.; Sydney Univ., Australia; Oslo Universitetet, Norway)

    1987-01-01

    Observed Stokes profiles of Mg I 4571 A are analyzed as a diagnostic of the magnetic field and thermal structure at the temperature minimum of sunspot umbrae. Multilevel non-LTE transfer calculations of the Mg I-II-III excitation and ionization balance in model umbral atmospheres show: (1) Mg I to be far less ionized in sunspot umbrae than in the quiet sun, leading to greatly enhanced opacity in 4571 A, and (2) LTE excitation of 4571 A. Existing umbral models predict emission cores of the Stokes I profile due to the chromospheric temperature rise. This feature is not present in observed umbral profiles. Moreover, such an emission reversal causes similar anomalous features in the Stokes Q, U, V profiles, which are also not observed. Umbral atmospheres with extended temperature minima are suggested. Implications for chromospheric heating mechanisms and the utility of this line for solar vector magnetic field measurements are discussed. 35 references

  20. TRANSITION-REGION/CORONAL SIGNATURES AND MAGNETIC SETTING OF SUNSPOT PENUMBRAL JETS: HINODE (SOT/FG), Hi-C, AND SDO/AIA OBSERVATIONS

    International Nuclear Information System (INIS)

    Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R.; Alpert, Shane E.

    2016-01-01

    Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al. using the Ca ii H-line filter on Hinode's Solar Optical Telescope (SOT). It was proposed that the PJs form as a result of reconnection between two magnetic components of penumbrae (spines and interspines), and that they could contribute to the transition region (TR) and coronal heating above sunspot penumbrae. We propose a modified picture of formation of PJs based on recent results on the internal structure of sunspot penumbral filaments. Using data of a sunspot from Hinode/SOT, High Resolution Coronal Imager, and different passbands of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we examine whether PJs have signatures in the TR and corona. We find hardly any discernible signature of normal PJs in any AIA passbands, except for a few of them showing up in the 1600 Å images. However, we discovered exceptionally stronger jets with similar lifetimes but bigger sizes (up to 600 km wide) occurring repeatedly in a few locations in the penumbra, where evidence of patches of opposite-polarity fields in the tails of some penumbral filaments is seen in Stokes-V images. These tail PJs do display signatures in the TR. Whether they have any coronal-temperature plasma is unclear. We infer that none of the PJs, including the tail PJs, directly heat the corona in active regions significantly, but any penumbral jet might drive some coronal heating indirectly via the generation of Alfvén waves and/or braiding of the coronal field

  1. An econometric investigation of the sunspot number record since the year 1700 and its prediction into the 22nd century

    Science.gov (United States)

    Travaglini, Guido

    2015-09-01

    Solar activity, as measured by the yearly revisited time series of sunspot numbers (SSN) for the period 1700-2014 (Clette et al., 2014), undergoes in this paper a triple statistical and econometric checkup. The conclusions are that the SSN sequence: (1) is best modeled as a signal that features nonlinearity in mean and variance, long memory, mean reversion, 'threshold' symmetry, and stationarity; (2) is best described as a discrete damped harmonic oscillator which linearly approximates the flux-transport dynamo model; (3) its prediction well into the 22nd century testifies of a substantial fall of the SSN centered around the year 2030. In addition, the first and last Gleissberg cycles show almost the same peak number and height during the period considered, yet the former slightly prevails when measured by means of the estimated smoother. All of these conclusions are achieved by making use of modern tools developed in the field of Financial Econometrics and of two new proposed procedures for signal smoothing and prediction.

  2. The effect of line damping, magneto-optics and parasitic light on the derivation of sunspot vector magnetic fields

    Science.gov (United States)

    Skumanich, A.; Lites, B. W.

    1985-01-01

    The least square fitting of Stokes observations of sunspots using a Milne-Eddington-Unno model appears to lead, in many circumstances, to various inconsistencies such as anomalously large doppler widths and, hence, small magnetic fields which are significantly below those inferred solely from the Zeeman splitting in the intensity profile. It is found that the introduction of additional physics into the model such as the inclusion of damping wings and magneto-optic birefrigence significantly improves the fit to Stokes parameters. Model fits excluding the intensity profile, i.e., of both magnitude as well as spectral shape of the polarization parameters alone, suggest that parasitic light in the intensity profile may also be a source of inconsistencies. The consequences of the physical changes on the vector properties of the field derived from the Fe I lambda 6173 line for the 17 November 1975 spot as well as on the thermodynamic state are discussed. A Doppler width delta lambda (D) - 25mA is bound to be consistent with a low spot temperature and microturbulence, and a damping constant of a = 0.2.

  3. Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Tanmoy; Banerjee, Dipankar [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Tian, Hui [School of Earth and Space Sciences, Peking University (China); Schanche, Nicole, E-mail: tsamanta@iiap.res.in, E-mail: huitian@pku.edu.cn, E-mail: dipu@iiap.res.in, E-mail: ns81@st-andrews.ac.uk [University of St. Andrews, St. Andrews (United Kingdom)

    2017-02-01

    Recent high-resolution observations have revealed that subarcsecond bright dots (BDs) with sub-minute lifetimes appear ubiquitously in the transition region (TR) above sunspot penumbra. The presence of penumbral micro-jets (PMJs) in the chromosphere was previously reported. It was proposed that both the PMJs and BDs are formed due to a magnetic reconnection process and may play an important role in heating of the penumbra. Using simultaneous observations of the chromosphere from the Solar Optical Telescope (SOT) on board Hinode and observations of the TR from the Interface Region Imaging Spectrograph , we study the dynamics of BDs and their relation to PMJs. We find two types of BDs, one that is related to PMJs, and another that does not show any visible dynamics in the SOT Ca ii H images. From a statistical analysis we show that these two types have different properties. The BDs that are related to PMJs always appear at the top of the PMJs, the vast majority of which show inward motion and originate before the generation of the PMJs. These results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere. This formation mechanism is in contrast with the formation of PMJs by reconnection in the (upper) photosphere between differently inclined fields.

  4. The Harm that Underestimation of Uncertainty Does to Our Community: A Case Study Using Sunspot Area Measurements

    Science.gov (United States)

    Munoz-Jaramillo, Andres

    2017-08-01

    Data products in heliospheric physics are very often provided without clear estimates of uncertainty. From helioseismology in the solar interior, all the way to in situ solar wind measurements beyond 1AU, uncertainty estimates are typically hard for users to find (buried inside long documents that are separate from the data products), or simply non-existent.There are two main reasons why uncertainty measurements are hard to find:1. Understanding instrumental systematic errors is given a much higher priority inside instrumental teams.2. The desire to perfectly understand all sources of uncertainty postpones indefinitely the actual quantification of uncertainty in our measurements.Using the cross calibration of 200 years of sunspot area measurements as a case study, in this presentation we will discuss the negative impact that inadequate measurements of uncertainty have on users, through the appearance of toxic and unnecessary controversies, and data providers, through the creation of unrealistic expectations regarding the information that can be extracted from their data. We will discuss how empirical estimates of uncertainty represent a very good alternative to not providing any estimates at all, and finalize by discussing the bare essentials that should become our standard practice for future instruments and surveys.

  5. A STATISTICAL STUDY OF FLARE PRODUCTIVITY ASSOCIATED WITH SUNSPOT PROPERTIES IN DIFFERENT MAGNETIC TYPES OF ACTIVE REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ya-Hui [Institute of Space Science, National Central University, Jhongli 32001, Taiwan (China); Hsieh, Min-Shiu [Geophysical Institute, University of Alaska Fairbanks, AK 99775-7320 (United States); Yu, Hsiu-Shan [Center for Astrophysics and Space Sciences, University of California San Diego, CA 92093 (United States); Chen, P. F., E-mail: yhyang@jupiter.ss.ncu.edu.tw, E-mail: mhsieh2@alaska.edu, E-mail: hsyu@ucsd.edu, E-mail: chenpf@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China)

    2017-01-10

    It is often believed that intense flares preferentially originate from the large-size active regions (ARs) with strong magnetic fields and complex magnetic configurations. This work investigates the dependence of flare activity on the AR properties and clarifies the influence of AR magnetic parameters on the flare productivity, based on two data sets of daily sunspot and flare information as well as the GOES soft X-ray measurements and HMI vector magnetograms. By considering the evolution of magnetic complexity, we find that flare behaviors are quite different in the short- and long-lived complex ARs and the ARs with more complex magnetic configurations are likely to host more impulsive and intense flares. Furthermore, we investigate several magnetic quantities and perform the two-sample Kolmogorov–Smirnov test to examine the similarity/difference between two populations in different types of ARs. Our results demonstrate that the total source field strength on the photosphere has a good correlation with the flare activity in complex ARs. It is noted that intense flares tend to occur at the regions of strong source field in combination with an intermediate field-weighted shear angle. This result implies that the magnetic free energy provided by a complex AR could be high enough to trigger a flare eruption even with a moderate magnetic shear on the photosphere. We thus suggest that the magnetic free energy represented by the source field rather than the photospheric magnetic complexity is a better quantity to characterize the flare productivity of an AR, especially for the occurrence of intense flares.

  6. Resonant behaviour of MHD waves on magnetic flux tubes. I - Connection formulae at the resonant surfaces. II - Absorption of sound waves by sunspots

    Science.gov (United States)

    Sakurai, Takashi; Goossens, Marcel; Hollweg, Joseph V.

    1991-01-01

    The present method of addressing the resonance problems that emerge in such MHD phenomena as the resonant absorption of waves at the Alfven resonance point avoids solving the fourth-order differential equation of dissipative MHD by recourse to connection formulae across the dissipation layer. In the second part of this investigation, the absorption of solar 5-min oscillations by sunspots is interpreted as the resonant absorption of sounds by a magnetic cylinder. The absorption coefficient is interpreted (1) analytically, under certain simplifying assumptions, and numerically, under more general conditions. The observed absorption coefficient magnitude is explained over suitable parameter ranges.

  7. Solar Indices - Sunspot Numbers

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  8. Skills, sunspots and cycles

    DEFF Research Database (Denmark)

    Busato, Francesco; Marchetti, Enrico

    This paper explores the ability of a class of one-sector,multi-input models to generate indeterminate equilibrium paths, andendogenous cycles, without relying on factors' hoarding. The modelpresents a novel theoretical economic mechanism that supportssunspot-driven expansions without requiring...

  9. Sunspot proper motions in active region NOAA 2372 and its flare activity during SMY period of 1980 April 4-13

    International Nuclear Information System (INIS)

    Ambastha, A.; Bhatnagar, A.

    1988-01-01

    Solar Active Region NOAA 2372 was observed extensively by the Solar Maximum Mission (SMM) satellite and several ground-based observatories during 1980 April 4-13 in the Solar Maximum Year. After its birth around April 4, it underwent a rapid growth and produced a reported 84 flares in the course of its disc passage. In this paper, photospheric and chromospheric observations of this active region have been studied together with Marshall Space Flight Center magnetograms and X-ray data from HXIS aboard the SMM satellite. In particular, the relationship of the flare-productivity with sunspot proper motions and emergence of new regions of magnetic flux in the active region from its birth to its disappearance at the W-limb has been discussed. (author). 7 figures, 2 tables, 29 refs

  10. Development of a Woven-Grid Quasi-BiPolar Battery

    National Research Council Canada - National Science Library

    Tokumaru, P

    1998-01-01

    .... Even so, quasi-bipolar batteries can be designed, with ten times better thermal uniformity, that meet or exceed current state of the art hybrid electric vehicle battery pack performance, even using...

  11. A theory of the Earth's magnetic field and of sunspots, based on a self-excited dynamo incorporating the Hall effect

    Directory of Open Access Journals (Sweden)

    A. de Paor

    2001-01-01

    Full Text Available A new viewpoint on the generation and maintenance of the Earth's magnetic field is put forward, which integrates self-exciting dynamo theory with the possibility of energy coupling along orthogonal axes provided by the Hall effect. A nonlinear third-order system is derived, with a fourth equation serving as an observer of unspecified geophysical processes which could result in field reversal. Lyapunov analysis proves that chaos is not intrinsic to this system. Relative constancy of one of the variables produces pseudo equilibrium in a second order subsystem and allows for self-excitation of the geomagnetic field. Electromagnetic analysis yields expressions for key parameters. Models for secular variations recorded at London, Palermo and at the Cape of Good Hope over the past four hundred years are offered. Offset of the Earth's magnetic axis from the geographic axis is central to time-varying declination, but its causes have not yet been established. Applicability of the model to the explanation of sunspot activity is outlined. A corroborating experiment published by Peter Barlow in 1831 is appended.

  12. Probability Estimates of Solar Particle Event Doses During a Period of Low Sunspot Number for Thinly-Shielded Spacecraft and Short Duration Missions

    Science.gov (United States)

    Atwell, William; Tylka, Allan J.; Dietrich, William; Rojdev, Kristina; Matzkind, Courtney

    2016-01-01

    In an earlier paper (Atwell, et al., 2015), we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the sunspot number (SSN) was less than 30. These SPEs contain Ground Level Events (GLE), sub-GLEs, and sub-sub-GLEs (Tylka and Dietrich, 2009, Tylka and Dietrich, 2008, and Atwell, et al., 2008). GLEs are extremely energetic solar particle events having proton energies extending into the several GeV range and producing secondary particles in the atmosphere, mostly neutrons, observed with ground station neutron monitors. Sub-GLE events are less energetic, extending into the several hundred MeV range, but do not produce secondary atmospheric particles. Sub-sub GLEs are even less energetic with an observable increase in protons at energies greater than 30 MeV, but no observable proton flux above 300 MeV. In this paper, we consider those SPEs that occurred during 1973-2010 when the SSN was greater than 30 but less than 50. In addition, we provide probability estimates of absorbed dose based on mission duration with a 95% confidence level (CL). We also discuss the implications of these data and provide some recommendations that may be useful to spacecraft designers of these smaller spacecraft.

  13. STUDY OF RAPID FORMATION OF A δ SUNSPOT ASSOCIATED WITH THE 2012 JULY 2 C7.4 FLARE USING HIGH-RESOLUTION OBSERVATIONS OF THE NEW SOLAR TELESCOPE

    International Nuclear Information System (INIS)

    Wang Haimin; Liu Chang; Wang Shuo; Deng Na; Xu Yan; Jing Ju; Cao Wenda

    2013-01-01

    Rapid, irreversible changes of magnetic topology and sunspot structure associated with flares have been systematically observed in recent years. The most striking features include the increase of the horizontal field at the polarity inversion line (PIL) and the co-spatial penumbral darkening. A likely explanation of the above phenomenon is the back reaction to the coronal restructuring after eruptions: a coronal mass ejection carries the upward momentum while the downward momentum compresses the field lines near the PIL. Previous studies could only use low-resolution (above 1'') magnetograms and white-light images. Therefore, the changes are mostly observed for X-class flares. Taking advantage of the 0.''1 spatial resolution and 15 s temporal cadence of the New Solar Telescope at the Big Bear Solar Observatory, we report in detail the rapid formation of sunspot penumbra at the PIL associated with the C7.4 flare on 2012 July 2. It is unambiguously shown that the solar granulation pattern evolves to an alternating dark and bright fibril structure, the typical pattern of penumbra. Interestingly, the appearance of such a penumbra creates a new δ sunspot. The penumbral formation is also accompanied by the enhancement of the horizontal field observed using vector magnetograms from the Helioseismic and Magnetic Imager. We explain our observations as being due to the eruption of a flux rope following magnetic cancellation at the PIL. Subsequently, the re-closed arcade fields are pushed down toward the surface to form the new penumbra. NLFFF extrapolation clearly shows both the flux rope close to the surface and the overlying fields

  14. The Extreme Solar Activity during October–November 2003 K. M. ...

    Indian Academy of Sciences (India)

    between occurrence of the abnormal activities of big sunspot groups that ... better statistics, we add the data of the sunspot positional measurements obtained from the ... Ai are the area values of the sunspot group for i number of observations.

  15. Group X

    Energy Technology Data Exchange (ETDEWEB)

    Fields, Susannah

    2007-08-16

    This project is currently under contract for research through the Department of Homeland Security until 2011. The group I was responsible for studying has to remain confidential so as not to affect the current project. All dates, reference links and authors, and other distinguishing characteristics of the original group have been removed from this report. All references to the name of this group or the individual splinter groups has been changed to 'Group X'. I have been collecting texts from a variety of sources intended for the use of recruiting and radicalizing members for Group X splinter groups for the purpose of researching the motivation and intent of leaders of those groups and their influence over the likelihood of group radicalization. This work included visiting many Group X websites to find information on splinter group leaders and finding their statements to new and old members. This proved difficult because the splinter groups of Group X are united in beliefs, but differ in public opinion. They are eager to tear each other down, prove their superiority, and yet remain anonymous. After a few weeks of intense searching, a list of eight recruiting texts and eight radicalizing texts from a variety of Group X leaders were compiled.

  16. Group Flow and Group Genius

    Science.gov (United States)

    Sawyer, Keith

    2015-01-01

    Keith Sawyer views the spontaneous collaboration of group creativity and improvisation actions as "group flow," which organizations can use to function at optimum levels. Sawyer establishes ideal conditions for group flow: group goals, close listening, complete concentration, being in control, blending egos, equal participation, knowing…

  17. Permutation groups

    CERN Document Server

    Passman, Donald S

    2012-01-01

    This volume by a prominent authority on permutation groups consists of lecture notes that provide a self-contained account of distinct classification theorems. A ready source of frequently quoted but usually inaccessible theorems, it is ideally suited for professional group theorists as well as students with a solid background in modern algebra.The three-part treatment begins with an introductory chapter and advances to an economical development of the tools of basic group theory, including group extensions, transfer theorems, and group representations and characters. The final chapter feature

  18. Sunspots and the Newcomb-Benford Law. (Spanish Title: Manchas Solares y la Ley de Newcomb-Benford.) Manchas Solares e a Lei de Newcomb-Benford

    Science.gov (United States)

    Alves, Mauro A.; Lyra, Cássia S.

    2008-12-01

    The Newcomb-Benford's Law (LNB) of first digits is introduced to high school students in an extracurricular activity through the study of sunspots. The LNB establishes that the first digits of various sets of data describing natural occurrences are not distributed uniformly, but according to a logarithmic distribution of probability. The LNB is counter-intuitive and is a good example of how mathematics applied to the study of natural phenomena can provide surprising and unexpected results serving also as a motivating agent in the study of physical sciences. En este trabajo se describe una actividad extracurricular donde se presenta a los estudiantes la ley de los primeros dígitos de Newcomb-Benford (LNB) con el estudio de manchas solares. La LNB establece que los primeros dígitos de algunos tipos de dados de ocurrencia natural no están distribuidos en manera uniforme, pero sí de acuerdo con una distribución logarítmica de probabilidad. La LNB es contra-intuitiva y es un excelente ejemplo de como las matemáticas aplicadas al estudio de fenómenos naturales pueden sorprender al estudiante, sirviendo también como elemento motivador en la educación de ciencias y de matemáticas. Este trabalho descreve uma atividade extracurricular na qual a lei dos primeiros dígitos de Newcomb-Benford (LNB) é introduzida a estudantes através do estudo de manchas solares. A LNB estabelece que os primeiros dígitos de vários tipos de conjunto de dados de ocorrência natural não são distribuídos de maneira uniforme, mas sim de acordo com uma distribuição logarítmica de probabilidade. A LNB é contra-intuitiva e é um ótimo exemplo de como a matemática aplicada ao estudo de fenômenos naturais pode fornecer resultados surpreendentes e inesperados, servindo também como um agente motivador no ensino de ciências e matemática.

  19. Group devaluation and group identification

    NARCIS (Netherlands)

    Leach, C.W.; Rodriguez Mosquera, P.M.; Vliek, M.L.W.; Hirt, E.

    2010-01-01

    In three studies, we showed that increased in-group identification after (perceived or actual) group devaluation is an assertion of a (preexisting) positive social identity that counters the negative social identity implied in societal devaluation. Two studies with real-world groups used order

  20. Lie groups and algebraic groups

    Indian Academy of Sciences (India)

    We give an exposition of certain topics in Lie groups and algebraic groups. This is not a complete ... of a polynomial equation is equivalent to the solva- bility of the equation ..... to a subgroup of the group of roots of unity in k (in particular, it is a ...

  1. Group Work

    Science.gov (United States)

    Wilson, Kristy J.; Brickman, Peggy; Brame, Cynthia J.

    2018-01-01

    Science, technology, engineering, and mathematics faculty are increasingly incorporating both formal and informal group work in their courses. Implementing group work can be improved by an understanding of the extensive body of educational research studies on this topic. This essay describes an online, evidence-based teaching guide published by…

  2. Reflection groups

    International Nuclear Information System (INIS)

    Eggermont, G.

    2006-01-01

    In 2005, PISA organised proactive meetings of reflection groups on involvement in decision making, expert culture and ethical aspects of radiation protection.All reflection group meetings address particular targeted audiences while the output publication in book form is put forward

  3. Group theory

    CERN Document Server

    Scott, W R

    2010-01-01

    Here is a clear, well-organized coverage of the most standard theorems, including isomorphism theorems, transformations and subgroups, direct sums, abelian groups, and more. This undergraduate-level text features more than 500 exercises.

  4. Group Grammar

    Science.gov (United States)

    Adams, Karen

    2015-01-01

    In this article Karen Adams demonstrates how to incorporate group grammar techniques into a classroom activity. In the activity, students practice using the target grammar to do something they naturally enjoy: learning about each other.

  5. Computer group

    International Nuclear Information System (INIS)

    Bauer, H.; Black, I.; Heusler, A.; Hoeptner, G.; Krafft, F.; Lang, R.; Moellenkamp, R.; Mueller, W.; Mueller, W.F.; Schati, C.; Schmidt, A.; Schwind, D.; Weber, G.

    1983-01-01

    The computer groups has been reorganized to take charge for the general purpose computers DEC10 and VAX and the computer network (Dataswitch, DECnet, IBM - connections to GSI and IPP, preparation for Datex-P). (orig.)

  6. Group learning

    DEFF Research Database (Denmark)

    Pimentel, Ricardo; Noguira, Eloy Eros da Silva; Elkjær, Bente

    The article presents a study that aims at the apprehension of the group learning in a top management team composed by teachers in a Brazilian Waldorf school whose management is collective. After deciding to extend the school, they had problems recruiting teachers who were already trained based...... on the Steiner´s ideas, which created practical problems for conducting management activities. The research seeks to understand how that group of teachers collectively manage the school, facing the lack of resources, a significant heterogeneity in the relationships, and the conflicts and contradictions......, and they are interrelated to the group learning as the construction, maintenance and reconstruction of the intelligibility of practices. From this perspective, it can be said that learning is a practice and not an exceptional phenomenon. Building, maintaining and rebuilding the intelligibility is the group learning...

  7. Group technology

    International Nuclear Information System (INIS)

    Rome, C.P.

    1976-01-01

    Group Technology has been conceptually applied to the manufacture of batch-lots of 554 machined electromechanical parts which now require 79 different types of metal-removal tools. The products have been grouped into 7 distinct families which require from 8 to 22 machines in each machine-cell. Throughput time can be significantly reduced and savings can be realized from tooling, direct-labor, and indirect-labor costs

  8. Abelian groups

    CERN Document Server

    Fuchs, László

    2015-01-01

    Written by one of the subject’s foremost experts, this book focuses on the central developments and modern methods of the advanced theory of abelian groups, while remaining accessible, as an introduction and reference, to the non-specialist. It provides a coherent source for results scattered throughout the research literature with lots of new proofs. The presentation highlights major trends that have radically changed the modern character of the subject, in particular, the use of homological methods in the structure theory of various classes of abelian groups, and the use of advanced set-theoretical methods in the study of undecidability problems. The treatment of the latter trend includes Shelah’s seminal work on the undecidability in ZFC of Whitehead’s Problem; while the treatment of the former trend includes an extensive (but non-exhaustive) study of p-groups, torsion-free groups, mixed groups, and important classes of groups arising from ring theory. To prepare the reader to tackle these topics, th...

  9. Indeterminacy, sunspots, and development traps

    Czech Academy of Sciences Publication Activity Database

    Slobodyan, Sergey

    2005-01-01

    Roč. 29, 1-2 (2005), s. 159-185 ISSN 0165-1889 Institutional research plan: CEZ:AV0Z70850503 Keywords : indeterminacy * development trap * stochastic stability Subject RIV: AH - Economics Impact factor: 0.691, year: 2005 http://dx.doi.org/10.1016/j.jedc.2003.04.011

  10. Group dynamics.

    Science.gov (United States)

    Scandiffio, A L

    1990-12-01

    Group dynamics play a significant role within any organization, culture, or unit. The important thing to remember with any of these structures is that they are made up of people--people with different ideas, motivations, background, and sometimes different agendas. Most groups, formal or informal, look for a leader in an effort to maintain cohesiveness of the unit. At times, that cultural bond must be developed; once developed, it must be nurtured. There are also times that one of the group no longer finds the culture comfortable and begins to act out behaviorally. It is these times that become trying for the leader as she or he attempts to remain objective when that which was once in the building phase of group cohesiveness starts to fall apart. At all times, the manager must continue to view the employee creating the disturbance as an integral part of the group. It is at this time that it is beneficial to perceive the employee exhibiting problem behaviors as a special employee, as one who needs the benefit of your experience and skills, as one who is still part of the group. It is also during this time that the manager should focus upon her or his own views in the area of power, communication, and the corporate culture of the unit that one has established before attempting to understand another's point of view. Once we understand our own motivation and accept ourselves, it is then that we may move on to offer assistance to another. Once we understand our insecurities recognizing staff dysfunction as a symptom of system dysfunction will not be so threatening to the concept of the manager that we perceive ourselves to be. It takes a secure person to admit that she or he favors staff before deciding to do something to change things. The important thing to know is that it can be done. The favored staff can find a new way of relating to others, the special employee can find new modes of behavior (and even find self-esteem in the process), the group can find new ways

  11. Group representations

    CERN Document Server

    Karpilovsky, G

    1994-01-01

    This third volume can be roughly divided into two parts. The first part is devoted to the investigation of various properties of projective characters. Special attention is drawn to spin representations and their character tables and to various correspondences for projective characters. Among other topics, projective Schur index and projective representations of abelian groups are covered. The last topic is investigated by introducing a symplectic geometry on finite abelian groups. The second part is devoted to Clifford theory for graded algebras and its application to the corresponding theory

  12. Lego Group

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Pedersen, Torben; Slepniov, Dmitrij

    2010-01-01

    The last years’ rather adventurous journey from 2004 to 2009 had taught the fifth-largest toy-maker in the world - the LEGO Group - the importance of managing the global supply chain effectively. In order to survive the largest internal financial crisis in its roughly 70 years of existence......, the management had, among many initiatives, decided to offshore and outsource a major chunk of its production to Flextronics. In this pursuit of rapid cost-cutting sourcing advantages, the LEGO Group planned to license out as much as 80 per cent of its production besides closing down major parts...

  13. Informal groups

    NARCIS (Netherlands)

    E. van den Berg; P. van Houwelingen; J. de Hart

    2011-01-01

    Original title: Informele groepen Going out running with a group of friends, rather than joining an official sports club. Individuals who decide to take action themselves rather than giving money to good causes. Maintaining contact with others not as a member of an association, but through an

  14. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group, established at the start of 2010, has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure There are now 55 CMS Centres worldwide that are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS offline and computing operations, hosting dedicated analysis efforts such as during the CMS Heavy Ion lead-lead running. With a majority of CMS sub-detectors now operating in a “shifterless” mode, many monitoring operations are now routinely performed from there, rather than in the main Control Room at P5. The CMS Communications Group, CERN IT and the EVO team are providing excellent videoconferencing support for the rapidly-increasing number of CMS meetings. In parallel, CERN IT and ...

  15. Group therapy

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    Full text: In his review 'Genesis of Unified Gauge Theories' at the symposium in Honour of Abdus Salam (June, page 23), Tom Kibble of Imperial College, London, looked back to the physics events around Salam from 1959-67. He described how, in the early 1960s, people were pushing to enlarge the symmetry of strong interactions beyond the SU(2) of isospin and incorporate the additional strangeness quantum number. Kibble wrote - 'Salam had students working on every conceivable symmetry group. One of these was Yuval Ne'eman, who had the good fortune and/or prescience to work on SU(3). From that work, and of course from the independent work of Murray Gell- Mann, stemmed the Eightfold Way, with its triumphant vindication in the discovery of the omega-minus in 1964.' Yuval Ne'eman writes - 'I was the Defence Attaché at the Israeli Embassy in London and was admitted by Salam as a part-time graduate student when I arrived in 1958. I started research after resigning from the Embassy in May 1960. Salam suggested a problem: provide vector mesons with mass - the problem which was eventually solved by Higgs, Guralnik, Kibble,.... (as described by Kibble in his article). I explained to Salam that I had become interested in symmetry. Nobody at Imperial College at the time, other than Salam himself, was doing anything in groups, and attention further afield was focused on the rotation - SO(N) - groups. Reacting to my own half-baked schemes, Salam told me to forget about the rotation groups he taught us, and study group theory in depth, directing me to Eugene Dynkin's classification of Lie subalgebras, about which he had heard from Morton Hamermesh. I found Dynkin incomprehensible without first learning about Lie algebras from Henri Cartan's thesis, which luckily had been reproduced by Dynkin in his 1946 thesis, using his diagram method. From a copy of a translation of Dynkin's thesis which I found in the British Museum Library, I

  16. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The CMS Communications Group, established at the start of 2010, has been strengthening the activities in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The Communications Group has invested a lot of effort to support the operations needs of CMS. Hence, the CMS Centres where physicists work on remote CMS shifts, Data Quality Monitoring, and Data Analysis are running very smoothly. There are now 55 CMS Centres worldwide, up from just 16 at the start of CMS data-taking. The latest to join are Imperial College London, the University of Iowa, and the Università di Napoli. The CMS Centre@CERN in Meyrin, which is now full repaired after the major flooding at the beginning of the year, has been at the centre of CMS offline and computing operations, most recently hosting a large fraction of the CMS Heavy Ion community during the lead-lead run. A number of sub-detector shifts can now take pla...

  17. Group play

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects of the v......Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects...... of the various formats used by RPGs on the gaming experience. This article presents the results of an empirical study, examining how multi-player tabletop RPGs are affected as they are ported to the digital medium. Issues examined include the use of disposition assessments to predict play experience, the effect...... of group dynamics, the influence of the fictional game characters and the comparative play experience between the two formats. The results indicate that group dynamics and the relationship between the players and their digital characters, are integral to the quality of the gaming experience in multiplayer...

  18. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS Offline and Computing operations, and a number of subdetector shifts can now take place there, rather than in the main Control Room at P5. A new CMS meeting room has been equipped for videoconferencing in building 42, next to building 40. Our building 28 meeting room and the facilities at P5 will be refurbished soon and plans are underway to steadily upgrade the ageing equipment in all 15 CMS meeting rooms at CERN. The CMS evaluation of the Vidyo tool indicates that it is not yet ready to be considered as a potential replacement for EVO. The Communications Group provides the CMS-TV (web) cha...

  19. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The recently established CMS Communications Group, led by Lucas Taylor, has been busy in all three of its main are areas of responsibility: Communications Infrastructure, Information Systems, and Outreach and Education Communications Infrastructure The damage caused by the flooding of the CMS Centre@CERN on 21st December has been completely repaired and all systems are back in operation. Major repairs were made to the roofs, ceilings and one third of the floor had to be completely replaced. Throughout these works, the CMS Centre was kept operating and even hosted a major press event for first 7 TeV collisions, as described below. Incremental work behind the scenes is steadily improving the quality of the CMS communications infrastructure, particularly Webcasting, video conferencing, and meeting rooms at CERN. CERN/IT is also deploying a pilot service of a new videoconference tool called Vidyo, to assess whether it might provide an enhanced service at a lower cost, compared to the EVO tool currently in w...

  20. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin is particularly busy at the moment, hosting about 50 physicists taking part in the heavy-ion data-taking and analysis. Three new CMS meeting room will be equipped for videoconferencing in early 2012: 40/5B-08, 42/R-031, and 28/S-029. The CMS-TV service showing LHC Page 1, CMS Page 1, etc. (http://cmsdoc.cern.ch/cmscc/projector/index.jsp) is now also available for mobile devices: http://cern.ch/mcmstv. Figure 12: Screenshots of CMS-TV for mobile devices Information Systems CMS has a new web site: (http://cern.ch/cms) using a modern web Content Management System to ensure content and links are managed and updated easily and coherently. It covers all CMS sub-projects and groups, replacing the iCMS internal pages. It also incorporates the existing CMS public web site (http:/...

  1. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2012-01-01

      Outreach and Education We are fortunate that our research has captured the public imagination, even though this inevitably puts us under the global media spotlight, as we saw with the Higgs seminar at CERN in December, which had 110,000 distinct webcast viewers. The media interest was huge with 71 media organisations registering to come to CERN to cover the Higgs seminar, which was followed by a press briefing with the DG and Spokespersons. This event resulted in about 2,000 generally positive stories in the global media. For this seminar, the CMS Communications Group prepared up-to-date news and public material, including links to the CMS results, animations and event displays [http://cern.ch/go/Ch8thttp://cern.ch/go/Ch8t]. There were 44,000 page-views on the CMS public website, with the Higgs news article being by far the most popular item. CMS event displays from iSpy are fast becoming the iconic media images, featuring on numerous major news outlets (BBC, CNN, MSN...) as well as in the sci...

  2. Which finite simple groups are unit groups?

    DEFF Research Database (Denmark)

    Davis, Christopher James; Occhipinti, Tommy

    2014-01-01

    We prove that if G is a finite simple group which is the unit group of a ring, then G is isomorphic to either (a) a cyclic group of order 2; (b) a cyclic group of prime order 2^k −1 for some k; or (c) a projective special linear group PSLn(F2) for some n ≥ 3. Moreover, these groups do all occur a...

  3. Group Cohesion in Experiential Growth Groups

    Science.gov (United States)

    Steen, Sam; Vasserman-Stokes, Elaina; Vannatta, Rachel

    2014-01-01

    This article explores the effect of web-based journaling on changes in group cohesion within experiential growth groups. Master's students were divided into 2 groups. Both used a web-based platform to journal after each session; however, only 1 of the groups was able to read each other's journals. Quantitative data collected before and…

  4. Group Work Publication-1991.

    Science.gov (United States)

    Zimpfer, David G.

    1992-01-01

    Lists 21 new publications in group work, of which 9 are reviewed. Those discussed include publications on group counseling and psychotherapy, structured groups, support groups, psychodrama, and social group work. (Author/NB)

  5. Quantum isometry groups

    Indian Academy of Sciences (India)

    Jyotishman Bhowmick

    2015-11-07

    Nov 7, 2015 ... Classical. Quantum. Background. Compact Hausdorff space. Unital C∗ algebra. Gelfand-Naimark. Compact Group. Compact Quantum Group. Woronowicz. Group Action. Coaction. Woronowicz. Riemannian manifold. Spectral triple. Connes. Isometry group. Quantum Isometry Group. To be discussed.

  6. Group typicality, group loyalty and cognitive development.

    Science.gov (United States)

    Patterson, Meagan M

    2014-09-01

    Over the course of childhood, children's thinking about social groups changes in a variety of ways. Developmental Subjective Group Dynamics (DSGD) theory emphasizes children's understanding of the importance of conforming to group norms. Abrams et al.'s study, which uses DSGD theory as a framework, demonstrates the social cognitive skills underlying young elementary school children's thinking about group norms. Future research on children's thinking about groups and group norms should explore additional elements of this topic, including aspects of typicality beyond loyalty. © 2014 The British Psychological Society.

  7. AREVA group overview; Presentation du groupe AREVA

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-08

    This document presents the Group Areva, a world nuclear industry leader, from a financial holding company to an industrial group, operating in two businesses: the nuclear energy and the components. The structure and the market of the group are discussed, as the financial assets. (A.L.B.)

  8. Overgroups of root groups in classical groups

    CERN Document Server

    Aschbacher, Michael

    2016-01-01

    The author extends results of McLaughlin and Kantor on overgroups of long root subgroups and long root elements in finite classical groups. In particular he determines the maximal subgroups of this form. He also determines the maximal overgroups of short root subgroups in finite classical groups and the maximal overgroups in finite orthogonal groups of c-root subgroups.

  9. Interagency mechanical operations group numerical systems group

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-09-01

    This report consists of the minutes of the May 20-21, 1971 meeting of the Interagency Mechanical Operations Group (IMOG) Numerical Systems Group. This group looks at issues related to numerical control in the machining industry. Items discussed related to the use of CAD and CAM, EIA standards, data links, and numerical control.

  10. Theory of Lie groups

    CERN Document Server

    Chevalley, Claude

    2018-01-01

    The standard text on the subject for many years, this introductory treatment covers classical linear groups, topological groups, manifolds, analytic groups, differential calculus of Cartan, and compact Lie groups and their representations. 1946 edition.

  11. The Global Land-Ocean Temperature Index in Relation to Sunspot Number, the Atlantic Multidecadal Oscillation Index, the Mauna Loa Atmospheric Concentration of CO2, and Anthropogenic Carbon Emissions

    Science.gov (United States)

    Wilson, Robert M.

    2013-01-01

    Global warming/climate change has been a subject of scientific interest since the early 19th century. In particular, increases in the atmospheric concentration of carbon dioxide (CO2) have long been thought to account for Earth's increased warming, although the lack of a dependable set of observational data was apparent as late as the mid 1950s. However, beginning in the late 1950s, being associated with the International Geophysical Year, the opportunity arose to begin accurate continuous monitoring of the Earth's atmospheric concentration of CO2. Consequently, it is now well established that the atmospheric concentration of CO2, while varying seasonally within any particular year, has steadily increased over time. Associated with this rising trend in the atmospheric concentration of CO2 is a rising trend in the surface-air and sea-surface temperatures (SSTs). This Technical Publication (TP) examines the statistical relationships between 10-year moving averages (10-yma) of the Global Land-Ocean Temperature Index (GLOTI), sunspot number (SSN), the Atlantic Multidecadal Oscillation (AMO) index, and the Mauna Loa CO2 (MLCO2) index for the common interval 1964-2006, where the 10-yma values are used to indicate trends in the data. Scatter plots using the 10-yma values between GLOTI and each of the other parameters are determined, both as single-variate and multivariate fits. Scatter plots are also determined for MLCO2 using single-variate and bivariate (BV) fits, based on the GLOTI alone and the GLOTI in combination with the AMO index. On the basis of the inferred preferential fits for MLCO2, estimates for MLCO2 are determined for the interval 1885-1964, thereby yielding an estimate of the preindustrial level of atmospheric concentration of CO2. Lastly, 10-yma values of MLCO2 are compared against 10-yma estimates of the total carbon emissions (TCE) to determine the likelihood that manmade sources of carbon emissions are indeed responsible for the recent warming now

  12. Introduction to Sporadic Groups

    Directory of Open Access Journals (Sweden)

    Luis J. Boya

    2011-01-01

    Full Text Available This is an introduction to finite simple groups, in particular sporadic groups, intended for physicists. After a short review of group theory, we enumerate the 1+1+16=18 families of finite simple groups, as an introduction to the sporadic groups. These are described next, in three levels of increasing complexity, plus the six isolated ''pariah'' groups. The (old five Mathieu groups make up the first, smallest order level. The seven groups related to the Leech lattice, including the three Conway groups, constitute the second level. The third and highest level contains the Monster group M, plus seven other related groups. Next a brief mention is made of the remaining six pariah groups, thus completing the 5+7+8+6=26 sporadic groups. The review ends up with a brief discussion of a few of physical applications of finite groups in physics, including a couple of recent examples which use sporadic groups.

  13. Group Work: How to Use Groups Effectively

    Science.gov (United States)

    Burke, Alison

    2011-01-01

    Many students cringe and groan when told that they will need to work in a group. However, group work has been found to be good for students and good for teachers. Employers want college graduates to have developed teamwork skills. Additionally, students who participate in collaborative learning get better grades, are more satisfied with their…

  14. Free Boolean Topological Groups

    Directory of Open Access Journals (Sweden)

    Ol’ga Sipacheva

    2015-11-01

    Full Text Available Known and new results on free Boolean topological groups are collected. An account of the properties that these groups share with free or free Abelian topological groups and properties specific to free Boolean groups is given. Special emphasis is placed on the application of set-theoretic methods to the study of Boolean topological groups.

  15. Small Group Research

    Science.gov (United States)

    McGrath, Joseph E.

    1978-01-01

    Summarizes research on small group processes by giving a comprehensive account of the types of variables primarily studied in the laboratory. These include group structure, group composition, group size, and group relations. Considers effects of power, leadership, conformity to social norms, and role relationships. (Author/AV)

  16. Geometric group theory

    CERN Document Server

    Druţu, Cornelia

    2018-01-01

    The key idea in geometric group theory is to study infinite groups by endowing them with a metric and treating them as geometric spaces. This applies to many groups naturally appearing in topology, geometry, and algebra, such as fundamental groups of manifolds, groups of matrices with integer coefficients, etc. The primary focus of this book is to cover the foundations of geometric group theory, including coarse topology, ultralimits and asymptotic cones, hyperbolic groups, isoperimetric inequalities, growth of groups, amenability, Kazhdan's Property (T) and the Haagerup property, as well as their characterizations in terms of group actions on median spaces and spaces with walls. The book contains proofs of several fundamental results of geometric group theory, such as Gromov's theorem on groups of polynomial growth, Tits's alternative, Stallings's theorem on ends of groups, Dunwoody's accessibility theorem, the Mostow Rigidity Theorem, and quasiisometric rigidity theorems of Tukia and Schwartz. This is the f...

  17. Profinite graphs and groups

    CERN Document Server

    Ribes, Luis

    2017-01-01

    This book offers a detailed introduction to graph theoretic methods in profinite groups and applications to abstract groups. It is the first to provide a comprehensive treatment of the subject. The author begins by carefully developing relevant notions in topology, profinite groups and homology, including free products of profinite groups, cohomological methods in profinite groups, and fixed points of automorphisms of free pro-p groups. The final part of the book is dedicated to applications of the profinite theory to abstract groups, with sections on finitely generated subgroups of free groups, separability conditions in free and amalgamated products, and algorithms in free groups and finite monoids. Profinite Graphs and Groups will appeal to students and researchers interested in profinite groups, geometric group theory, graphs and connections with the theory of formal languages. A complete reference on the subject, the book includes historical and bibliographical notes as well as a discussion of open quest...

  18. Cobalt bis(dicarbollide) ions with covalently bonded CMPO groups as selective extraction agents for lanthanide and actinide cations from highly acidic nuclear waste solutions

    International Nuclear Information System (INIS)

    Gruner, B.; Plesek, J.; Baca, J.; Cisarova, I.; Dozol, J.F.; Rouquette, H.; Vinas, C.; Selucky, P.; Rais, J.

    2002-01-01

    A new series of boron substituted cobalt bis(dicarbollide)(1-) ion (1) derivatives of the general formula [(8-CMPO-(CH 2 -CH 2 O) 2 -1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )-3,3'-Co] - (CMPO = Ph 2 P(O)-CH 2 C(O)NR, R = C 4 H 9 (3b), -C 12 H 25 (4b), -CH 2 -C 6 H 5 (5b)) was prepared by ring cleavage of the 8-dioxane-cobalt bis(dicarbollide) (2) bi-polar compound by the respective primary amines and by subsequent reaction of the resulting amino derivatives (3a-5a) with the nitrophenyl ester of diphenyl-phosphoryl-acetic acid. The compounds were synthesized with the aim to develop a new class of more efficient extraction agents for liquid/liquid extraction of polyvalent cations, i.e. lanthanides and actinides, from high-level activity nuclear waste. All compounds were characterized by a combination of 11 B NMR, 1 H high field NMR, Mass Spectrometry with Electro-spray and MALDI TOF ionisation, HPLC and other techniques. The molecular structure of the supramolecular Ln 3+ complex of the anion 5b was determined by single crystal X-ray diffraction analysis. Crystallographic results proved that the Ln(m) atom is bonded to three functionalized cobalt bis(dicarbollide) anions in a charge compensated complex. The cation is tightly coordinated by six oxygen atoms of the CMPO terminal groups (two of each ligand) and by three water molecules completing the metal coordination number to 9. Atoms occupying the primary coordination sphere form a tri-capped trigonal prismatic arrangement. Very high liquid-liquid extraction efficiency of all anionic species was observed. Moreover, less polar toluene can be applied as an auxiliary solvent replacing the less environmentally friendly nitro- and chlorinated solvents used in the current dicarbollide liquid-liquid extraction process. The extraction coefficients are sufficiently high for possible technological applications. (authors)

  19. Group purchasing: an overview.

    Science.gov (United States)

    Wetrich, J G

    1987-07-01

    The various types and operational methods of purchasing groups are described, and evaluation of groups is discussed. Since group purchasing is increasing in popularity as a method of controlling drug costs, community and hospital pharmacy managers may need to evaluate various groups to determine the appropriateness of their services. Groups are categorized as independent, system based, or alliance or association based. Instead of "purchasing," some groups develop contracts for hospitals, which then purchase directly from the vendor. Aside from this basic difference between groups that purchase and groups that contract, comparisons among groups are difficult because of the wide variation in sizes and services. Competition developing from diversification among groups has led to "super groups," formed from local and regional groups. In evaluating groups, advantages and disadvantages germane to accomplishing the member's objectives must be considered. To ensure a group's success, members must be committed and support the group's philosophies; hospital pharmacists must help to establish a strong formulary system. To select vendors, groups should develop formal qualification and selection criteria and should not base a decision solely on price. The method of solicitation (bidding or negotiating), as well as the role of the prime vendor, should be studied. Legal implications of group purchasing, especially in the areas of administrative fees and drug diversion, must also be considered. The most advantageous group for each organization will include members with common missions and will be able to implement strategies for future success.

  20. Ordered groups and infinite permutation groups

    CERN Document Server

    1996-01-01

    The subjects of ordered groups and of infinite permutation groups have long en­ joyed a symbiotic relationship. Although the two subjects come from very different sources, they have in certain ways come together, and each has derived considerable benefit from the other. My own personal contact with this interaction began in 1961. I had done Ph. D. work on sequence convergence in totally ordered groups under the direction of Paul Conrad. In the process, I had encountered "pseudo-convergent" sequences in an ordered group G, which are like Cauchy sequences, except that the differences be­ tween terms of large index approach not 0 but a convex subgroup G of G. If G is normal, then such sequences are conveniently described as Cauchy sequences in the quotient ordered group GIG. If G is not normal, of course GIG has no group structure, though it is still a totally ordered set. The best that can be said is that the elements of G permute GIG in an order-preserving fashion. In independent investigations around that t...

  1. Sunspot waves and flare energy release

    Czech Academy of Sciences Publication Activity Database

    Sych, R.A.; Karlický, Marian; Altyntsev, A.; Dudík, Jaroslav; Kashapova, L. K.

    2015-01-01

    Roč. 577, May (2015), A43/1-A43/8 ISSN 0004-6361 R&D Projects: GA ČR GAP209/12/0103; GA ČR GAP209/12/1652 Grant - others:EC(XE) 606862 Program:FP7 Institutional support: RVO:67985815 Keywords : Sun flares * Sun oscillations * Sun X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

  2. The Relative Phase Asynchronization between Sunspot Numbers ...

    Indian Academy of Sciences (India)

    of Sciences, P. O. Box 110, 650011 Kunming, People's Republic of China. ... by studying the North–South asymmetry in the predominant rotation periods of ... earth, the polar faculae counts show strong annual variation, and the polar region is.

  3. A GEOMETRICAL HEIGHT SCALE FOR SUNSPOT PENUMBRAE

    International Nuclear Information System (INIS)

    Puschmann, K. G.; Ruiz Cobo, B.; MartInez Pillet, V.

    2010-01-01

    Inversions of spectropolarimetric observations of penumbral filaments deliver the stratification of different physical quantities in an optical depth scale. However, without establishing a geometrical height scale, their three-dimensional geometrical structure cannot be derived. This is crucial in understanding the correct spatial variation of physical properties in the penumbral atmosphere and to provide insights into the mechanism capable of explaining the observed penumbral brightness. The aim of this work is to determine a global geometrical height scale in the penumbra by minimizing the divergence of the magnetic field vector and the deviations from static equilibrium as imposed by a force balance equation that includes pressure gradients, gravity, and the Lorentz force. Optical depth models are derived from the inversion of spectropolarimetric data of an active region observed with the Solar Optical Telescope on board the Hinode satellite. We use a genetic algorithm to determine the boundary condition for the inference of geometrical heights. The retrieved geometrical height scale permits the evaluation of the Wilson depression at each pixel and the correlation of physical quantities at each height. Our results fit into the uncombed penumbral scenario, i.e., a penumbra composed of flux tubes with channeled mass flow and with a weaker and more horizontal magnetic field as compared with the background field. The ascending material is hotter and denser than their surroundings. We do not find evidence of overturning convection or field-free regions in the inner penumbral area analyzed. The penumbral brightness can be explained by the energy transfer of the ascending mass carried by the Evershed flow, if the physical quantities below z = -75 km are extrapolated from the results of the inversion.

  4. ALIGNMENTS OF GROUP GALAXIES WITH NEIGHBORING GROUPS

    International Nuclear Information System (INIS)

    Wang Yougang; Chen Xuelei; Park, Changbom; Yang Xiaohu; Choi, Yun-Young

    2009-01-01

    Using a sample of galaxy groups found in the Sloan Digital Sky Survey Data Release 4, we measure the following four types of alignment signals: (1) the alignment between the distributions of the satellites of each group relative to the direction of the nearest neighbor group (NNG); (2) the alignment between the major axis direction of the central galaxy of the host group (HG) and the direction of the NNG; (3) the alignment between the major axes of the central galaxies of the HG and the NNG; and (4) the alignment between the major axes of the satellites of the HG and the direction of the NNG. We find strong signal of alignment between the satellite distribution and the orientation of central galaxy relative to the direction of the NNG, even when the NNG is located beyond 3r vir of the host group. The major axis of the central galaxy of the HG is aligned with the direction of the NNG. The alignment signals are more prominent for groups that are more massive and with early-type central galaxies. We also find that there is a preference for the two major axes of the central galaxies of the HG and NNG to be parallel for the system with both early central galaxies, however, not for the systems with both late-type central galaxies. For the orientation of satellite galaxies, we do not find any significant alignment signals relative to the direction of the NNG. From these four types of alignment measurements, we conclude that the large-scale environment traced by the nearby group affects primarily the shape of the host dark matter halo, and hence also affects the distribution of satellite galaxies and the orientation of central galaxies. In addition, the NNG directly affects the distribution of the satellite galaxies by inducing asymmetric alignment signals, and the NNG at very small separation may also contribute a second-order impact on the orientation of the central galaxy in the HG.

  5. Citizens' action group

    International Nuclear Information System (INIS)

    Andritzky, W.

    1978-01-01

    For the first empirical study of citizens' action groups 331 such groups were consulted. Important information was collected on the following aspects of these groups: their self-image, areas and forms of activities, objectives and their extent, how long the group has existed, successes and failures and their forms of organisation. (orig.) [de

  6. Communication in Organizational Groups

    OpenAIRE

    Monica RADU

    2007-01-01

    Organizational group can be defined as some persons between who exist interactive connections (functional, communication, affective, normative type). Classification of these groups can reflect the dimension, type of relationship or type of rules included. Organizational groups and their influence over the individual efficiency and the efficiency of the entire group are interconnected. Spontaneous roles in these groups sustain the structure of the relationship, and the personality of each indi...

  7. [Social crisis, spontaneous groups and group order].

    Science.gov (United States)

    Edelman, Lucila; Kordon, Diana

    2002-12-01

    Argentina has gone through very difficult times during the last years and, in particularly, new kinds of social practices have emerged in order to cope with the crisis. This situation demands and urges a new type of reflection upon the double role of groups, as tools to transform reality and as a way to elaborate those processes regarding subjectivity. In this paper we analyse some topics regarding the groupal field (considering spontaneous groups as well as groupal devices that allow to elaborate the crisis). We consider social bond to be the condition of possibility for the existence of the psyche and of time continuity, and that it also makes possible personal and social elaboration of trauma, crisis and social catastrophe. We develop some aspects of an specific device (the reflection group), which we have already depicted in another moment, showing it's usefulness to cope with social crisis and to promote the subjective elaboration of crisis.

  8. Introduction to topological groups

    CERN Document Server

    Husain, Taqdir

    2018-01-01

    Concise treatment covers semitopological groups, locally compact groups, Harr measure, and duality theory and some of its applications. The volume concludes with a chapter that introduces Banach algebras. 1966 edition.

  9. MSUD Family Support Group

    Science.gov (United States)

    ... The Treatment Of MSUD The MSUD Family Support Group has provided funds to Buck Institute for its ... of the membership of the MSUD Family Support Group, research for improved treatments and potential cure was ...

  10. Nilpotent -local finite groups

    Science.gov (United States)

    Cantarero, José; Scherer, Jérôme; Viruel, Antonio

    2014-10-01

    We provide characterizations of -nilpotency for fusion systems and -local finite groups that are inspired by known result for finite groups. In particular, we generalize criteria by Atiyah, Brunetti, Frobenius, Quillen, Stammbach and Tate.

  11. UPIN Group File

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Group Unique Physician Identifier Number (UPIN) File is the business entity file that contains the group practice UPIN and descriptive information. It does NOT...

  12. Group Decision Process Support

    DEFF Research Database (Denmark)

    Gøtze, John; Hijikata, Masao

    1997-01-01

    Introducing the notion of Group Decision Process Support Systems (GDPSS) to traditional decision-support theorists.......Introducing the notion of Group Decision Process Support Systems (GDPSS) to traditional decision-support theorists....

  13. Gestalt Interactional Groups

    Science.gov (United States)

    Harman, Robert L.; Franklin, Richard W.

    1975-01-01

    Gestalt therapy in groups is not limited to individual work in the presence of an audience. Describes several ways to involve gestalt groups interactionally. Interactions described focus on learning by doing and discovering, and are noninterpretive. (Author/EJT)

  14. Group B streptococcus - pregnancy

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000511.htm Group B streptococcus - pregnancy To use the sharing features on this page, please enable JavaScript. Group B streptococcus (GBS) is a type of bacteria that some ...

  15. Multicultural group work

    DEFF Research Database (Denmark)

    Hansen, Annette Skovsted

    2014-01-01

    Motivation for the activity I use this strategy for forming groups to ensure diverse/multicultural groups that combine a variety of different strengths and resources based on student's academic, disciplinary, linguistic, national, personal and work backgrounds.......Motivation for the activity I use this strategy for forming groups to ensure diverse/multicultural groups that combine a variety of different strengths and resources based on student's academic, disciplinary, linguistic, national, personal and work backgrounds....

  16. The Areva Group; Le groupe Areva

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-08-01

    This document provides information on the Areva Group, a world nuclear industry leader, offering solutions for nuclear power generation, electricity transmission and distribution and interconnect systems to the telecommunications, computer and automotive markets. It presents successively the front end division including the group business lines involved in producing nuclear fuel for electric power generation (uranium mining, concentration, conversion and enrichment and nuclear fuel fabrication); the reactors and services division which designs and builds PWR, BWR and research reactors; the back end division which encompasses the management of the fuel that has been used in nuclear power plants; the transmission and distribution division which provides products, systems and services to the medium and high voltage energy markets; the connectors division which designs and manufactures electrical, electronic and optical connectors, flexible micro circuitry and interconnection systems. Areva is implemented in Europe, north and south america, africa and asia-pacific. (A.L.B.)

  17. Groups, combinatorics and geometry

    CERN Document Server

    Ivanov, A A; Saxl, J

    2003-01-01

    Over the past 20 years, the theory of groups in particular simplegroups, finite and algebraic has influenced a number of diverseareas of mathematics. Such areas include topics where groups have beentraditionally applied, such as algebraic combinatorics, finitegeometries, Galois theory and permutation groups, as well as severalmore recent developments.

  18. Working Group 7 Summary

    Energy Technology Data Exchange (ETDEWEB)

    Nagaitsev S.; Berg J.

    2012-06-10

    The primary subject of working group 7 at the 2012 Advanced Accelerator Concepts Workshop was muon accelerators for a muon collider or neutrino factory. Additionally, this working group included topics that did not fit well into other working groups. Two subjects were discussed by more than one speaker: lattices to create a perfectly integrable nonlinear lattice, and a Penning trap to create antihydrogen.

  19. AREVA group overview

    International Nuclear Information System (INIS)

    2002-01-01

    This document presents the Group Areva, a world nuclear industry leader, from a financial holding company to an industrial group, operating in two businesses: the nuclear energy and the components. The structure and the market of the group are discussed, as the financial assets. (A.L.B.)

  20. ATP-binding motifs play key roles in Krp1p, kinesin-related protein 1, function for bi-polar growth control in fission yeast

    International Nuclear Information System (INIS)

    Rhee, Dong Keun; Cho, Bon A; Kim, Hyong Bai

    2005-01-01

    Kinesin is a microtubule-based motor protein with various functions related to the cell growth and division. It has been reported that Krp1p, kinesin-related protein 1, which belongs to the kinesin heavy chain superfamily, localizes on microtubules and may play an important role in cytokinesis. However, the function of Krp1p has not been fully elucidated. In this study, we overexpressed an intact form and three different mutant forms of Krp1p in fission yeast constructed by site-directed mutagenesis in two ATP-binding motifs or by truncation of the leucine zipper-like motif (LZiP). We observed hyper-extended microtubules and the aberrant nuclear shape in Krp1p-overexpressed fission yeast. As a functional consequence, a point mutation of ATP-binding domain 1 (G89E) in Krp1p reversed the effect of Krp1p overexpression in fission yeast, whereas the specific mutation in ATP-binding domain 2 (G238E) resulted in the altered cell polarity. Additionally, truncation of the leucine zipper-like domain (LZiP) at the C-terminal of Krp1p showed a normal nuclear division. Taken together, we suggest that krp1p is involved in regulation of cell-polarized growth through ATP-binding motifs in fission yeast

  1. Group Psychotherapy in Denmark.

    Science.gov (United States)

    Jørgensen, Lars Bo; Thygesen, Bente; Aagaard, Søren

    2015-10-01

    This is a short article on the history and training standards in the Institute of Group Analysis in Copenhagen (IGA-CPH). We describe theoretical orientations and influences in the long-term training program and new initiatives, like courses in mentalization-based group treatment and a dynamic short-term group therapy course, as well as research in group psychotherapy in Denmark. Some group analytic initiatives in relation to social issues and social welfare are presented, as well as initiatives concerning the school system and unemployment.

  2. Group theory I essentials

    CERN Document Server

    Milewski, Emil G

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Group Theory I includes sets and mapping, groupoids and semi-groups, groups, isomorphisms and homomorphisms, cyclic groups, the Sylow theorems, and finite p-groups.

  3. Lectures on Chevalley groups

    CERN Document Server

    Steinberg, Robert

    2016-01-01

    Robert Steinberg's Lectures on Chevalley Groups were delivered and written during the author's sabbatical visit to Yale University in the 1967-1968 academic year. The work presents the status of the theory of Chevalley groups as it was in the mid-1960s. Much of this material was instrumental in many areas of mathematics, in particular in the theory of algebraic groups and in the subsequent classification of finite groups. This posthumous edition incorporates additions and corrections prepared by the author during his retirement, including a new introductory chapter. A bibliography and editorial notes have also been added. This is a great unsurpassed introduction to the subject of Chevalley groups that influenced generations of mathematicians. I would recommend it to anybody whose interests include group theory. -Efim Zelmanov, University of California, San Diego Robert Steinberg's lectures on Chevalley groups were given at Yale University in 1967. The notes for the lectures contain a wonderful exposition of ...

  4. E-groups training

    CERN Multimedia

    HR Department

    2012-01-01

    There will be an e-groups training course on 16 March 2012 which will cover the main e-groups functionalities i.e.: creating and managing e-groups, difference between static and dynamic e-groups, configuring posting restrictions and archives, examples of where e-groups can be used in daily work. Even if you have already worked with e-groups, this may be a good opportunity to learn about the best practices and security related recommendations when using e-groups. You can find more details as well as enrolment form for the training (it’s free) here. The number of places is limited, so enrolling early is recommended.   Technical Training Tel. 72844

  5. Group Psychotherapy in Italy.

    Science.gov (United States)

    Giannone, Francesca; Giordano, Cecilia; Di Blasi, Maria

    2015-10-01

    This article describes the history and the prevailing orientations of group psychotherapy in Italy (psychoanalytically oriented, psychodrama, CBT groups) and particularly group analysis. Provided free of charge by the Italian health system, group psychotherapy is growing, but its expansion is patchy. The main pathways of Italian training in the different group psychotherapy orientations are also presented. Clinical-theoretical elaboration on self development, psychopathology related to group experiences, and the methodological attention paid to objectives and methods in different clinical groups are issues related to group therapy in Italy. Difficulties in the relationship between research and clinical practice are discussed, as well as the empirical research network that tries to bridge the gap between research and clinical work in group psychotherapy. The economic crisis in Italy has led to massive cuts in health care and to an increasing demand for some forms of psychological treatment. For these reasons, and because of its positive cost-benefit ratio, group psychotherapy is now considered an important tool in the national health care system to expand the clinical response to different forms of psychological distress.

  6. Geometric group theory

    CERN Document Server

    Bestvina, Mladen; Vogtmann, Karen

    2014-01-01

    Geometric group theory refers to the study of discrete groups using tools from topology, geometry, dynamics and analysis. The field is evolving very rapidly and the present volume provides an introduction to and overview of various topics which have played critical roles in this evolution. The book contains lecture notes from courses given at the Park City Math Institute on Geometric Group Theory. The institute consists of a set of intensive short courses offered by leaders in the field, designed to introduce students to exciting, current research in mathematics. These lectures do not duplicate standard courses available elsewhere. The courses begin at an introductory level suitable for graduate students and lead up to currently active topics of research. The articles in this volume include introductions to CAT(0) cube complexes and groups, to modern small cancellation theory, to isometry groups of general CAT(0) spaces, and a discussion of nilpotent genus in the context of mapping class groups and CAT(0) gro...

  7. CLASSIFICATION OF CRIMINAL GROUPS

    OpenAIRE

    Natalia Romanova

    2013-01-01

    New types of criminal groups are emerging in modern society.  These types have their special criminal subculture. The research objective is to develop new parameters of classification of modern criminal groups, create a new typology of criminal groups and identify some features of their subculture. Research methodology is based on the system approach that includes using the method of analysis of documentary sources (materials of a criminal case), method of conversations with themembers of the...

  8. Group therapy for adolescents

    OpenAIRE

    Nada Hribar

    2001-01-01

    The group included adolescents from secondary school and some students. The group had weekly sessions or twice on mounth. The adolescents had varied simptoms: depressive, anxiety, psychosomatic disorders, learning difficulties, cunduct problems. All of adolescents were common on many problems in social interactions. The goal of therapeutic work were: to increase assertiveness skills and to reduce the anxious in social situations. The adolescents in group raised a self-esteem and developed som...

  9. Presentations of groups

    CERN Document Server

    Johnson, D L

    1997-01-01

    The aim of this book is to provide an introduction to combinatorial group theory. Any reader who has completed first courses in linear algebra, group theory and ring theory will find this book accessible. The emphasis is on computational techniques but rigorous proofs of all theorems are supplied. This new edition has been revised throughout, including new exercises and an additional chapter on proving that certain groups are infinite.

  10. Group-Server Queues

    OpenAIRE

    Li, Quan-Lin; Ma, Jing-Yu; Xie, Mingzhou; Xia, Li

    2017-01-01

    By analyzing energy-efficient management of data centers, this paper proposes and develops a class of interesting {\\it Group-Server Queues}, and establishes two representative group-server queues through loss networks and impatient customers, respectively. Furthermore, such two group-server queues are given model descriptions and necessary interpretation. Also, simple mathematical discussion is provided, and simulations are made to study the expected queue lengths, the expected sojourn times ...

  11. Environmental groups in politics

    International Nuclear Information System (INIS)

    Lowe, P.; Goyder, J.

    1983-01-01

    The subject is covered in chapters, entitled: introduction; (Part I) the environmental movement (environmental groups and the attentive public; the episodic development of the environmental movement; the underlying values of environmentalism; the roots of environmental concern; the social limits to growth; elite manipulation of values); the organisation of environmental groups; environmental groups in national politics; environmental groups in local politics; (Part II) the Henley Society; Friends of the Earth; the National Trust; the Royal Society for Nature Conservation; the European Environmental Bureau. (U.K.)

  12. Complex quantum groups

    International Nuclear Information System (INIS)

    Drabant, B.; Schlieker, M.

    1993-01-01

    The complex quantum groups are constructed. They are q-deformations of the real Lie groups which are obtained as the complex groups corresponding to the Lie algebras of type A n-1 , B n , C n . Following the ideas of Faddeev, Reshetikhin and Takhtajan Hopf algebras of regular functionals U R for these complexified quantum groups are constructed. One has thus in particular found a construction scheme for the q-Lorentz algebra to be identified as U(sl q (2,C). (orig.)

  13. Explosive Technology Group

    Data.gov (United States)

    Federal Laboratory Consortium — The Explosive Technology Group (ETG) provides diverse technical expertise and an agile, integrated approach to solve complex challenges for all classes of energetic...

  14. Study Groups in Denmark

    DEFF Research Database (Denmark)

    Hjorth, Poul G.

    2007-01-01

    Since 1998 European Study Groups have been held in Denmark, and Danish companies from LEGO and NOVO to very small high-tech firms have participated. I briefly describe the history, the organisation and the format of the Danish Study Groups, and highlight a few problem solutions.......Since 1998 European Study Groups have been held in Denmark, and Danish companies from LEGO and NOVO to very small high-tech firms have participated. I briefly describe the history, the organisation and the format of the Danish Study Groups, and highlight a few problem solutions....

  15. Lie groups for pedestrians

    CERN Document Server

    Lipkin, Harry J

    2002-01-01

    According to the author of this concise, high-level study, physicists often shy away from group theory, perhaps because they are unsure which parts of the subject belong to the physicist and which belong to the mathematician. However, it is possible for physicists to understand and use many techniques which have a group theoretical basis without necessarily understanding all of group theory. This book is designed to familiarize physicists with those techniques. Specifically, the author aims to show how the well-known methods of angular momentum algebra can be extended to treat other Lie group

  16. The normal holonomy group

    International Nuclear Information System (INIS)

    Olmos, C.

    1990-05-01

    The restricted holonomy group of a Riemannian manifold is a compact Lie group and its representation on the tangent space is a product of irreducible representations and a trivial one. Each one of the non-trivial factors is either an orthogonal representation of a connected compact Lie group which acts transitively on the unit sphere or it is the isotropy representation of a single Riemannian symmetric space of rank ≥ 2. We prove that, all these properties are also true for the representation on the normal space of the restricted normal holonomy group of any submanifold of a space of constant curvature. 4 refs

  17. Trajectory grouping structure

    Directory of Open Access Journals (Sweden)

    Maike Buchin

    2015-03-01

    Full Text Available The collective motion of a set of moving entities like people, birds, or other animals, is characterized by groups arising, merging, splitting, and ending. Given the trajectories of these entities, we define and model a structure that captures all of such changes using the Reeb graph, a concept from topology. The trajectory grouping structure has three natural parameters that allow more global views of the data in group size, group duration, and entity inter-distance. We prove complexity bounds on the maximum number of maximal groups that can be present, and give algorithms to compute the grouping structure efficiently. We also study how the trajectory grouping structure can be made robust, that is, how brief interruptions of groups can be disregarded in the global structure, adding a notion of persistence to the structure. Furthermore, we showcase the results of experiments using data generated by the NetLogo flocking model and from the Starkey project. The Starkey data describe the movement of elk, deer, and cattle. Although there is no ground truth for the grouping structure in this data, the experiments show that the trajectory grouping structure is plausible and has the desired effects when changing the essential parameters. Our research provides the first complete study of trajectory group evolvement, including combinatorial,algorithmic, and experimental results.

  18. Computational methods working group

    International Nuclear Information System (INIS)

    Gabriel, T.A.

    1997-09-01

    During the Cold Moderator Workshop several working groups were established including one to discuss calculational methods. The charge for this working group was to identify problems in theory, data, program execution, etc., and to suggest solutions considering both deterministic and stochastic methods including acceleration procedures.

  19. GroupFinder

    DEFF Research Database (Denmark)

    Bøgh, Kenneth Sejdenfaden; Skovsgaard, Anders; Jensen, Christian S.

    2013-01-01

    . Such groups are relevant to users who wish to conveniently explore several options before making a decision such as to purchase a specific product. Specifically, we demonstrate a practical proposal for finding top-k PoI groups in response to a query. We show how problem parameter settings can be mapped...

  20. Toleration, Groups, and Multiculturalism

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2014-01-01

    have the ability to interfere with the group’s activities, an object of dislike or disapproval, an agent enjoying non-interference or a moral patient. This means that 'toleration of groups' can mean quite different things depending on the exact meaning of 'group' in relation to each component...

  1. Group B Strep Infection

    Science.gov (United States)

    ... IV) to kill the germs. If you take antibiotics while you’re in labor, the chances are very good that your baby won’t get this infection. What if my baby has group B strep? If your baby gets group B strep, he or she will be treated with IV antibiotics to kill the bacteria. Your baby will stay ...

  2. Group Process as Drama.

    Science.gov (United States)

    McLeod, John

    1984-01-01

    Suggests that drama, as well as training or therapy, may be employed as a useful research and practice paradigm in working with small groups. The implications of this view for group development as a whole, and for member and leader participation, are explored. (JAC)

  3. Group Work. Research Brief

    Science.gov (United States)

    Walker, Karen

    2010-01-01

    According to Johnson and Johnson, group work helps increase student retention and satisfaction, develops strong oral communication and social skills, as well as higher self-esteem (University of Minnesota, n.d.). Group work, when planned and implemented deliberately and thoughtfully helps students develop cognitive and leadership skills as well as…

  4. Physically detached 'compact groups'

    Science.gov (United States)

    Hernquist, Lars; Katz, Neal; Weinberg, David H.

    1995-01-01

    A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

  5. Introduction to quantum groups

    International Nuclear Information System (INIS)

    Sudbery, A.

    1996-01-01

    These pedagogical lectures contain some motivation for the study of quantum groups; a definition of ''quasi triangular Hopf algebra'' with explanations of all the concepts required to build it up; descriptions of quantised universal enveloping algebras and the quantum double; and an account of quantised function algebras and the action of quantum groups on quantum spaces. (author)

  6. Beam dynamics group summary

    International Nuclear Information System (INIS)

    Peggs, S.

    1994-01-01

    This paper summarizes the activities of the beam dynamics working group of the LHC Collective Effects Workshop that was held in Montreux in 1994. It reviews the presentations that were made to the group, the discussions that ensued, and the consensuses that evolved

  7. Our Deming Users' Group.

    Science.gov (United States)

    Dinklocker, Christina

    1992-01-01

    After training in the Total Quality Management concept, a suburban Ohio school district created a Deming Users' Group to link agencies, individuals, and ideas. The group has facilitated ongoing school/business collaboration, networking among individuals from diverse school systems, mentoring and cooperative learning activities, and resource…

  8. Asymmetry within social groups

    DEFF Research Database (Denmark)

    Barker, Jessie; Loope, Kevin J.; Reeve, H. Kern

    2016-01-01

    Social animals vary in their ability to compete with group members over shared resources and also vary in their cooperative efforts to produce these resources. Competition among groups can promote within-group cooperation, but many existing models of intergroup cooperation do not explicitly account...... of two roles, with relative competitive efficiency and the number of individuals varying between roles. Players in each role make simultaneous, coevolving decisions. The model predicts that although intergroup competition increases cooperative contributions to group resources by both roles, contributions...... are predominantly from individuals in the less competitively efficient role, whereas individuals in the more competitively efficient role generally gain the larger share of these resources. When asymmetry in relative competitive efficiency is greater, a group's per capita cooperation (averaged across both roles...

  9. Supervision and group dynamics

    DEFF Research Database (Denmark)

    Hansen, Søren; Jensen, Lars Peter

    2004-01-01

     An important aspect of the problem based and project organized study at Aalborg University is the supervision of the project groups. At the basic education (first year) it is stated in the curriculum that part of the supervisors' job is to deal with group dynamics. This is due to the experience...... that many students are having difficulties with practical issues such as collaboration, communication, and project management. Most supervisors either ignore this demand, because they do not find it important or they find it frustrating, because they do not know, how to supervise group dynamics...... as well as at Aalborg University. The first visible result has been participating supervisors telling us that the course has inspired them to try supervising group dynamics in the future. This paper will explore some aspects of supervising group dynamics as well as, how to develop the Aalborg model...

  10. Summary of group discussions

    International Nuclear Information System (INIS)

    2009-01-01

    A key aspect of the workshop was the interaction and exchange of ideas and information among the 40 participants. To facilitate this activity the workshop participants were divided into five discussions groups. These groups reviewed selected subjects and reported back to the main body with summaries of their considerations. Over the 3 days the 5 discussion groups were requested to focus on the following subjects: the characteristics and capabilities of 'good' organisations; how to ensure sufficient resources; how to ensure competence within the organisation; how to demonstrate organisational suitability; the regulatory oversight processes - including their strengths and weaknesses. A list of the related questions that were provided to the discussion groups can be found in Appendix 3. Also included in Appendix 3 are copies of the slides the groups prepared that summarised their considerations

  11. Natural analogue working group

    International Nuclear Information System (INIS)

    Come, B.; Chapman, N.

    1986-01-01

    A Natural Analogue Working Group was established by the Commission of the European Communities in 1985. The purpose of this group is to bring together modellers with earth scientists and others, so that maximum benefit can be obtained from natural analogue studies with a view to safe geological disposal of radioactive waste. The first meeting of this group was held in Brussels from November 5 to 7, 1985. The discussions mainly concerned the identification of the modellers' needs and of the earth scientists' capacity to provide for them. Following the debates, a written statement was produced by the Group; this document forms the core of the present Report. Notes and outlines of many of the presentations made are grouped in four appendixes. The valuable contribution of all those involved in the meeting is gratefully acknowledged

  12. Ordered groups and topology

    CERN Document Server

    Clay, Adam

    2016-01-01

    This book deals with the connections between topology and ordered groups. It begins with a self-contained introduction to orderable groups and from there explores the interactions between orderability and objects in low-dimensional topology, such as knot theory, braid groups, and 3-manifolds, as well as groups of homeomorphisms and other topological structures. The book also addresses recent applications of orderability in the studies of codimension-one foliations and Heegaard-Floer homology. The use of topological methods in proving algebraic results is another feature of the book. The book was written to serve both as a textbook for graduate students, containing many exercises, and as a reference for researchers in topology, algebra, and dynamical systems. A basic background in group theory and topology is the only prerequisite for the reader.

  13. Group prenatal care.

    Science.gov (United States)

    Mazzoni, Sara E; Carter, Ebony B

    2017-06-01

    Patients participating in group prenatal care gather together with women of similar gestational ages and 2 providers who cofacilitate an educational session after a brief medical assessment. The model was first described in the 1990s by a midwife for low-risk patients and is now practiced by midwives and physicians for both low-risk patients and some high-risk patients, such as those with diabetes. The majority of literature on group prenatal care uses CenteringPregnancy, the most popular model. The first randomized controlled trial of CenteringPregnancy showed that it reduced the risk of preterm birth in low-risk women. However, recent meta-analyses have shown similar rates of preterm birth, low birthweight, and neonatal intensive care unit admission between women participating in group prenatal care and individual prenatal care. There may be subgroups, such as African Americans, who benefit from this type of prenatal care with significantly lower rates of preterm birth. Group prenatal care seems to result in increased patient satisfaction and knowledge and use of postpartum family planning as well as improved weight gain parameters. The literature is inconclusive regarding breast-feeding, stress, depression, and positive health behaviors, although it is theorized that group prenatal care positively affects these outcomes. It is unclear whether group prenatal care results in cost savings, although it may in large-volume practices if each group consists of approximately 8-10 women. Group prenatal care requires a significant paradigm shift. It can be difficult to implement and sustain. More randomized trials are needed to ascertain the true benefits of the model, best practices for implementation, and subgroups who may benefit most from this innovative way to provide prenatal care. In short, group prenatal care is an innovative and promising model with comparable pregnancy outcomes to individual prenatal care in the general population and improved outcomes in some

  14. Critical groups - basic concepts

    International Nuclear Information System (INIS)

    Carter, M.W.

    1992-01-01

    The potential exposure pathways from the land application site to man are presented. It is emphasised that the critical group is not necessary the population group closest to the source. It could be the group impact by the most significant pathways(s). Only by assessing the importance of each of these pathways and then combining them can a proper choice of critical group be made. It would be wrong to select a critical group on the basis that it seems the most probable one, before the pathways have been properly assessed. A calculation in Carter (1983) suggested that for the operating mine site, the annual doses to an Aboriginal person, a service worker and a local housewife, were all about the same and were in the range 0.1 to 0.2 mSv per year. Thus it may be that for the land application area, the critical group turns out to be non-Aboriginal rather than the expected Aboriginal group. 6 refs., 3 figs

  15. Groups - Modular Mathematics Series

    CERN Document Server

    Jordan, David

    1994-01-01

    This text provides an introduction to group theory with an emphasis on clear examples. The authors present groups as naturally occurring structures arising from symmetry in geometrical figures and other mathematical objects. Written in a 'user-friendly' style, where new ideas are always motivated before being fully introduced, the text will help readers to gain confidence and skill in handling group theory notation before progressing on to applying it in complex situations. An ideal companion to any first or second year course on the topic.

  16. Introduction to quantum groups

    CERN Document Server

    Chaichian, Masud

    1996-01-01

    In the past decade there has been an extemely rapid growth in the interest and development of quantum group theory.This book provides students and researchers with a practical introduction to the principal ideas of quantum groups theory and its applications to quantum mechanical and modern field theory problems. It begins with a review of, and introduction to, the mathematical aspects of quantum deformation of classical groups, Lie algebras and related objects (algebras of functions on spaces, differential and integral calculi). In the subsequent chapters the richness of mathematical structure

  17. Group key management

    Energy Technology Data Exchange (ETDEWEB)

    Dunigan, T.; Cao, C.

    1997-08-01

    This report describes an architecture and implementation for doing group key management over a data communications network. The architecture describes a protocol for establishing a shared encryption key among an authenticated and authorized collection of network entities. Group access requires one or more authorization certificates. The implementation includes a simple public key and certificate infrastructure. Multicast is used for some of the key management messages. An application programming interface multiplexes key management and user application messages. An implementation using the new IP security protocols is postulated. The architecture is compared with other group key management proposals, and the performance and the limitations of the implementation are described.

  18. Group therapy for adolescents

    Directory of Open Access Journals (Sweden)

    Nada Hribar

    2001-03-01

    Full Text Available The group included adolescents from secondary school and some students. The group had weekly sessions or twice on mounth. The adolescents had varied simptoms: depressive, anxiety, psychosomatic disorders, learning difficulties, cunduct problems. All of adolescents were common on many problems in social interactions. The goal of therapeutic work were: to increase assertiveness skills and to reduce the anxious in social situations. The adolescents in group raised a self-esteem and developed some assertiveness skills: eye contact" and effective communication skills, persistence, refusing and requesting, giving and receiving critism, etc. The methods of work and techniques were based on principles of cognitive-behaviour therapy.

  19. Matrix groups for undergraduates

    CERN Document Server

    Tapp, Kristopher

    2005-01-01

    Matrix groups touch an enormous spectrum of the mathematical arena. This textbook brings them into the undergraduate curriculum. It makes an excellent one-semester course for students familiar with linear and abstract algebra and prepares them for a graduate course on Lie groups. Matrix Groups for Undergraduates is concrete and example-driven, with geometric motivation and rigorous proofs. The story begins and ends with the rotations of a globe. In between, the author combines rigor and intuition to describe basic objects of Lie theory: Lie algebras, matrix exponentiation, Lie brackets, and maximal tori.

  20. UnitedHealth Group

    Science.gov (United States)

    UnitedHealth Group provides accessible and affordable services, improved quality of care, coordinated health care efforts, and a supportive environment for shared decision making between patients and their physicians.

  1. Homogeneous group, research, institution

    Directory of Open Access Journals (Sweden)

    Francesca Natascia Vasta

    2014-09-01

    Full Text Available The work outlines the complex connection among empiric research, therapeutic programs and host institution. It is considered the current research state in Italy. Italian research field is analyzed and critic data are outlined: lack of results regarding both the therapeutic processes and the effectiveness of eating disorders group analytic treatment. The work investigates on an eating disorders homogeneous group, led into an eating disorder outpatient service. First we present the methodological steps the research is based on including the strong connection among theory and clinical tools. Secondly clinical tools are described and the results commented. Finally, our results suggest the necessity of validating some more specifical hypothesis: verifying the relationship between clinical improvement (sense of exclusion and painful emotions reduction and specific group therapeutic processes; verifying the relationship between depressive feelings, relapses and transition trough a more differentiated groupal field.Keywords: Homogeneous group; Eating disorders; Institutional field; Therapeutic outcome

  2. Color transparency study group

    International Nuclear Information System (INIS)

    Appel, J.A.; Pordes, S.; Botts, J.; Bunce, G.; Farrar, G.

    1990-01-01

    The group studied the relatively new notion of color transparency, discussed present experimental evidence for the effect, and explored several ideas for future experiments. This write-up summarizes these discussions. 11 refs., 1 fig

  3. Generalized quantum groups

    International Nuclear Information System (INIS)

    Leivo, H.P.

    1992-01-01

    The algebraic approach to quantum groups is generalized to include what may be called an anyonic symmetry, reflecting the appearance of phases more general than ±1 under transposition. (author). 6 refs

  4. Groups – Additive Notation

    Directory of Open Access Journals (Sweden)

    Coghetto Roland

    2015-06-01

    Full Text Available We translate the articles covering group theory already available in the Mizar Mathematical Library from multiplicative into additive notation. We adapt the works of Wojciech A. Trybulec [41, 42, 43] and Artur Korniłowicz [25].

  5. Groups – Additive Notation

    OpenAIRE

    Coghetto Roland

    2015-01-01

    We translate the articles covering group theory already available in the Mizar Mathematical Library from multiplicative into additive notation. We adapt the works of Wojciech A. Trybulec [41, 42, 43] and Artur Korniłowicz [25].

  6. Creativity and group innovation

    NARCIS (Netherlands)

    Nijstad, B.A.; de Dreu, C.K.W.

    2002-01-01

    Comments on M. West's article regarding the validity of an integrative model of creativity and innovation implementation in work groups. Variables affecting the level of team innovation; Relationship between predictors and team innovation; Promotion of constructive conflict.

  7. Truck shovel users group

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, J. [Surface Mining Association for Research and Technology, AB (Canada)

    2008-07-01

    The Truck Shovel Users Group (TSUG) was developed as part of the Surface Mining Association for Research and Technology (SMART), an association of companies that meet to coordinate technology developments for the mining industry. The TSUG meet regularly to discuss equipment upgrades, maintenance planning systems, and repair techniques. The group strives to maximize the value of its assets through increased safety, equipment performance and productivity. This presentation provided administrative details about the TSUG including contact details and admission costs. It was concluded that members of the group must be employed by companies that use heavy mining equipment, and must also be willing to host meetings, make presentations, and support the common goals of the group. tabs., figs.

  8. The theory of groups

    CERN Document Server

    Hall, Marshall

    2018-01-01

    This 1959 text offers an unsurpassed resource for learning and reviewing the basics of a fundamental and ever-expanding area. "This remarkable book undoubtedly will become a standard text on group theory." - American Scientist.

  9. Radiation Protection Group

    CERN Document Server

    2006-01-01

    The Radioactive Waste Section of the Radiation Protection Group wishes to inform you that the Radioactive Waste Treatment Centre will be closed on the afternoon of Tuesday 19 December 2006. Thank-you for your understanding.

  10. The Military Cooperation Group

    National Research Council Canada - National Science Library

    Renzi, Jr, Alfred E

    2006-01-01

    .... This thesis will describe a structure to assist with both those needs. The premise is that an expanded and improved network of US Military Groups is the weapon of choice for the war on terror, and beyond...

  11. Introduction to group theory

    Directory of Open Access Journals (Sweden)

    Canals B.

    2012-03-01

    Full Text Available This chapter is a concise mathematical introduction into the algebra of groups. It is build up in the way that definitions are followed by propositions and proofs. The concepts and the terminology introduced here will serve as a basis for the following chapters that deal with group theory in the stricter sense and its application to problems in physics. The mathematical prerequisites are at the bachelor level.1

  12. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  13. Focus Group Guide

    Science.gov (United States)

    2017-07-01

    home for the arrival of school- aged children. TIP: Do not conduct focus groups in a command conference room in the command group area. Doing so...organizational effectiveness and equal opportunity/equal employment opportunity/fair treatment and sexual assault and response factors (which are listed on the... Sexual Harassment (C) Sex Harassment Retaliation (D) Discrimination - Sex (E) Discrimination - Race (F) Discrimination - Disability (G

  14. Choice Shifts in Groups

    OpenAIRE

    Kfir Eliaz; Debraj Ray

    2004-01-01

    The phenomenon of "choice shifts" in group decision-making is fairly ubiquitous in the social psychology literature. Faced with a choice between a ``safe" and ``risky" decision, group members appear to move to one extreme or the other, relative to the choices each member might have made on her own. Both risky and cautious shifts have been identified in different situations. This paper demonstrates that from an individual decision-making perspective, choice shifts may be viewed as a systematic...

  15. Group Capability Model

    Science.gov (United States)

    Olejarski, Michael; Appleton, Amy; Deltorchio, Stephen

    2009-01-01

    The Group Capability Model (GCM) is a software tool that allows an organization, from first line management to senior executive, to monitor and track the health (capability) of various groups in performing their contractual obligations. GCM calculates a Group Capability Index (GCI) by comparing actual head counts, certifications, and/or skills within a group. The model can also be used to simulate the effects of employee usage, training, and attrition on the GCI. A universal tool and common method was required due to the high risk of losing skills necessary to complete the Space Shuttle Program and meet the needs of the Constellation Program. During this transition from one space vehicle to another, the uncertainty among the critical skilled workforce is high and attrition has the potential to be unmanageable. GCM allows managers to establish requirements for their group in the form of head counts, certification requirements, or skills requirements. GCM then calculates a Group Capability Index (GCI), where a score of 1 indicates that the group is at the appropriate level; anything less than 1 indicates a potential for improvement. This shows the health of a group, both currently and over time. GCM accepts as input head count, certification needs, critical needs, competency needs, and competency critical needs. In addition, team members are categorized by years of experience, percentage of contribution, ex-members and their skills, availability, function, and in-work requirements. Outputs are several reports, including actual vs. required head count, actual vs. required certificates, CGI change over time (by month), and more. The program stores historical data for summary and historical reporting, which is done via an Excel spreadsheet that is color-coded to show health statistics at a glance. GCM has provided the Shuttle Ground Processing team with a quantifiable, repeatable approach to assessing and managing the skills in their organization. They now have a common

  16. Parton Distributions Working Group

    International Nuclear Information System (INIS)

    Barbaro, L. de; Keller, S. A.; Kuhlmann, S.; Schellman, H.; Tung, W.-K.

    2000-01-01

    This report summarizes the activities of the Parton Distributions Working Group of the QCD and Weak Boson Physics workshop held in preparation for Run II at the Fermilab Tevatron. The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, the authors introduce a Manifesto that describes an optimal method for reporting data

  17. Renormalization Group Theory

    International Nuclear Information System (INIS)

    Stephens, C. R.

    2006-01-01

    In this article I give a brief account of the development of research in the Renormalization Group in Mexico, paying particular attention to novel conceptual and technical developments associated with the tool itself, rather than applications of standard Renormalization Group techniques. Some highlights include the development of new methods for understanding and analysing two extreme regimes of great interest in quantum field theory -- the ''high temperature'' regime and the Regge regime

  18. Independents' group posts loss

    International Nuclear Information System (INIS)

    Sanders, V.; Price, R.B.

    1992-01-01

    Low oil gas prices and special charges caused the group of 50 U.S. independent producers Oil and Gas Journal tracks to post a combined loss in first half 1992. The group logged a net loss of $53 million in the first half compared with net earnings of $354 million in first half 1991, when higher oil prices during the Persian Gulf crisis buoyed earnings in spite of crude oil and natural gas production declines. The combined loss in the first half follows a 45% drop in the group's earnings in 1991 and compares with the OGJ group of integrated oil companies whose first half 1992 income fell 47% from the prior year. Special charges, generally related to asset writedowns, accounted for most of the almost $560 million in losses posted by about the third of the group. Nerco Oil and Gas Inc., Vancouver, Wash., alone accounted for almost half that total with charges related to an asset writedown of $238 million in the first quarter. Despite the poor first half performance, the outlook is bright for sharply improved group earnings in the second half, assuming reasonably healthy oil and gas prices and increased production resulting from acquisitions and in response to those prices

  19. Assessment of Group Preferences and Group Uncertainty for Decision Making

    Science.gov (United States)

    1976-06-01

    the individ- uals. decision making , group judgments should be preferred to individual judgments if obtaining group judgments costs more. -26- -YI IV... decision making group . IV. A. 3. Aggregation using conjugate distribution. Arvther procedure for combining indivi(jai probability judgments into a group...statisticized group group decision making group judgment subjective probability Delphi method expected utility nominal group 20. ABSTRACT (Continue on

  20. Cyclic Soft Groups and Their Applications on Groups

    Directory of Open Access Journals (Sweden)

    Hacı Aktaş

    2014-01-01

    Full Text Available In crisp environment the notions of order of group and cyclic group are well known due to many applications. In this paper, we introduce order of the soft groups, power of the soft sets, power of the soft groups, and cyclic soft group on a group. We also investigate the relationship between cyclic soft groups and classical groups.

  1. Coordinating Group report

    International Nuclear Information System (INIS)

    1994-01-01

    In December 1992, western governors and four federal agencies established a Federal Advisory Committee to Develop On-site Innovative Technologies for Environmental Restoration and Waste Management (the DOIT Committee). The purpose of the Committee is to advise the federal government on ways to improve waste cleanup technology development and the cleanup of federal sites in the West. The Committee directed in January 1993 that information be collected from a wide range of potential stakeholders and that innovative technology candidate projects be identified, organized, set in motion, and evaluated to test new partnerships, regulatory approaches, and technologies which will lead to improve site cleanup. Five working groups were organized, one to develop broad project selection and evaluation criteria and four to focus on specific contaminant problems. A Coordinating Group comprised of working group spokesmen and federal and state representatives, was set up to plan and organize the routine functioning of these working groups. The working groups were charged with defining particular contaminant problems; identifying shortcomings in technology development, stakeholder involvement, regulatory review, and commercialization which impede the resolution of these problems; and identifying candidate sites or technologies which could serve as regional innovative demonstration projects to test new approaches to overcome the shortcomings. This report from the Coordinating Group to the DOIT Committee highlights the key findings and opportunities uncovered by these fact-finding working groups. It provides a basis from which recommendations from the DOIT Committee to the federal government can be made. It also includes observations from two public roundtables, one on commercialization and another on regulatory and institutional barriers impeding technology development and cleanup

  2. Linear algebraic groups

    CERN Document Server

    Springer, T A

    1998-01-01

    "[The first] ten chapters...are an efficient, accessible, and self-contained introduction to affine algebraic groups over an algebraically closed field. The author includes exercises and the book is certainly usable by graduate students as a text or for self-study...the author [has a] student-friendly style… [The following] seven chapters... would also be a good introduction to rationality issues for algebraic groups. A number of results from the literature…appear for the first time in a text." –Mathematical Reviews (Review of the Second Edition) "This book is a completely new version of the first edition. The aim of the old book was to present the theory of linear algebraic groups over an algebraically closed field. Reading that book, many people entered the research field of linear algebraic groups. The present book has a wider scope. Its aim is to treat the theory of linear algebraic groups over arbitrary fields. Again, the author keeps the treatment of prerequisites self-contained. The material of t...

  3. Summary report: injection group

    International Nuclear Information System (INIS)

    Simpson, J.; Ankenbrandt, C.; Brown, B.

    1984-01-01

    The injector group attempted to define and address several problem areas related to the SSC injector as defined in the Reference Design Study (RDS). It also considered the topic of machine utilization, particularly the question of test beam requirements. Details of the work are given in individually contributed papers, but the general concerns and consensus of the group are presented within this note. The group recognized that the injector as outlined in the RDS was developed primarily for costing estimates. As such, it was not necessarily well optimized from the standpoint of insuring the required beam properties for the SSC. On the other hand, considering the extraordinary short time in which the RDS was prepared, it is an impressive document and a good basis from which to work. Because the documented SSC performance goals are ambitious, the group sought an injector solution which would more likely guarantee that SSC performance not be limited by its injectors. As will be seen, this leads to a somewhat different solution than that described in the RDS. Furthermore, it is the consensus of the group that the new, conservative approach represents only a modest cost increase of the overall project well worth the confidence gained and the risks avoided

  4. Matrix groups for undergraduates

    CERN Document Server

    Tapp, Kristopher

    2016-01-01

    Matrix groups touch an enormous spectrum of the mathematical arena. This textbook brings them into the undergraduate curriculum. It makes an excellent one-semester course for students familiar with linear and abstract algebra and prepares them for a graduate course on Lie groups. Matrix Groups for Undergraduates is concrete and example-driven, with geometric motivation and rigorous proofs. The story begins and ends with the rotations of a globe. In between, the author combines rigor and intuition to describe the basic objects of Lie theory: Lie algebras, matrix exponentiation, Lie brackets, maximal tori, homogeneous spaces, and roots. This second edition includes two new chapters that allow for an easier transition to the general theory of Lie groups. From reviews of the First Edition: This book could be used as an excellent textbook for a one semester course at university and it will prepare students for a graduate course on Lie groups, Lie algebras, etc. … The book combines an intuitive style of writing w...

  5. Frailty Across Age Groups.

    Science.gov (United States)

    Pérez-Zepeda, M U; Ávila-Funes, J A; Gutiérrez-Robledo, L M; García-Peña, C

    2016-01-01

    The implementation of an aging biomarker into clinical practice is under debate. The Frailty Index is a model of deficit accumulation and has shown to accurately capture frailty in older adults, thus bridging biological with clinical practice. To describe the association of socio-demographic characteristics and the Frailty Index in different age groups (from 20 to over one hundred years) in a representative sample of Mexican subjects. Cross-sectional analysis. Nationwide and population-representative survey. Adults 20-years and older interviewed during the last Mexican National Health and Nutrition Survey (2012). A 30-item Frailty Index following standard construction was developed. Multi-level regression models were performed to test the associations of the Frailty Index with multiple socio-demographic characteristics across age groups. A total of 29,504 subjects was analyzed. The 30-item Frailty Index showed the highest scores in the older age groups, especially in women. No sociodemographic variable was associated with the Frailty Index in all the studied age groups. However, employment, economic income, and smoking status were more consistently found across age groups. To our knowledge, this is the first report describing the Frailty Index in a representative large sample of a Latin American country. Increasing age and gender were closely associated with a higher score.

  6. Illinois Wind Workers Group

    Energy Technology Data Exchange (ETDEWEB)

    David G. Loomis

    2012-05-28

    The Illinois Wind Working Group (IWWG) was founded in 2006 with about 15 members. It has grown to over 200 members today representing all aspects of the wind industry across the State of Illinois. In 2008, the IWWG developed a strategic plan to give direction to the group and its activities. The strategic plan identifies ways to address critical market barriers to the further penetration of wind. The key to addressing these market barriers is public education and outreach. Since Illinois has a restructured electricity market, utilities no longer have a strong control over the addition of new capacity within the state. Instead, market acceptance depends on willing landowners to lease land and willing county officials to site wind farms. Many times these groups are uninformed about the benefits of wind energy and unfamiliar with the process. Therefore, many of the project objectives focus on conferences, forum, databases and research that will allow these stakeholders to make well-educated decisions.

  7. Focus group discussions

    CERN Document Server

    Hennink, Monique M

    2014-01-01

    The Understanding Research series focuses on the process of writing up social research. The series is broken down into three categories: Understanding Statistics, Understanding Measurement, and Understanding Qualitative Research. The books provide researchers with guides to understanding, writing, and evaluating social research. Each volume demonstrates how research should be represented, including how to write up the methodology as well as the research findings. Each volume also reviews how to appropriately evaluate published research. Focus Group Discussions addresses the challenges associated with conducting and writing focus group research. It provides detailed guidance on the practical and theoretical considerations in conducting focus group discussions including: designing the discussion guide, recruiting participants, training a field team, moderating techniques and ethical considerations. Monique Hennink describes how a methodology section is read and evaluated by others, such as journal reviewers or ...

  8. Bell, group and tangle

    International Nuclear Information System (INIS)

    Solomon, A. I.

    2010-01-01

    The 'Bell' of the title refers to bipartite Bell states, and their extensions to, for example, tripartite systems. The 'Group' of the title is the Braid Group in its various representations; while 'Tangle' refers to the property of entanglement which is present in both of these scenarios. The objective of this note is to explore the relation between Quantum Entanglement and Topological Links, and to show that the use of the language of entanglement in both cases is more than one of linguistic analogy.

  9. A Quantum Groups Primer

    Science.gov (United States)

    Majid, Shahn

    2002-05-01

    Here is a self-contained introduction to quantum groups as algebraic objects. Based on the author's lecture notes for the Part III pure mathematics course at Cambridge University, the book is suitable as a primary text for graduate courses in quantum groups or supplementary reading for modern courses in advanced algebra. The material assumes knowledge of basic and linear algebra. Some familiarity with semisimple Lie algebras would also be helpful. The volume is a primer for mathematicians but it will also be useful for mathematical physicists.

  10. Introduction to quantum groups

    International Nuclear Information System (INIS)

    Monteiro, Marco A.R.

    1994-01-01

    An elementary introduction to quantum groups is presented. The example of Universal Enveloping Algebra of deformed SU(2) is analysed in detail. It is also discussed systems made up of bosonic q-oscillators at finite temperature within the formalism of Thermo-Field Dynamics. (author). 39 refs

  11. Lectures on Lie groups

    CERN Document Server

    Hsiang, Wu-Yi

    2017-01-01

    This volume consists of nine lectures on selected topics of Lie group theory. We provide the readers a concise introduction as well as a comprehensive 'tour of revisiting' the remarkable achievements of S Lie, W Killing, É Cartan and H Weyl on structural and classification theory of semi-simple Lie groups, Lie algebras and their representations; and also the wonderful duet of Cartans' theory on Lie groups and symmetric spaces.With the benefit of retrospective hindsight, mainly inspired by the outstanding contribution of H Weyl in the special case of compact connected Lie groups, we develop the above theory via a route quite different from the original methods engaged by most other books.We begin our revisiting with the compact theory which is much simpler than that of the general semi-simple Lie theory; mainly due to the well fittings between the Frobenius-Schur character theory and the maximal tori theorem of É Cartan together with Weyl's reduction (cf. Lectures 1-4). It is a wonderful reality of the Lie t...

  12. Gluten Intolerance Group

    Science.gov (United States)

    ... Intolerance Group (GIG), the industry leader in the certification of gluten-free products and food services, announced today that a wide ... of gluten-free products. One of the top certification programs in the world, GFCO inspects products and manufacturing facilities for gluten, in an effort ...

  13. With the Radiobiology Group

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    The Radiobiology Group carries out experiments to study the effect of radiation on living cells. The photo shows the apparatus for growing broad beans which have been irradiated by 250 GeV protons. The roots are immersed in a tank of running water (CERN Weekly Bulletin 26 January 1981 and Annual Report 1980 p. 160). Karen Panman, Marilena Streit-Bianchi, Roger Paris.

  14. Group control of elevators

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, Yasukazu; Hikita, Shiro; Tuji, Sintaro (Mitsubishi Electric Corp., Tokyo (Japan))

    1988-09-05

    Items to be evaluated in the group control of elevators, and a typical control system are described. A new system in which the fuzzy rule base is employed is introduced together with the configuration. The items to be evaluated are waiting time, riding time, accuracy of forecasting, energy saving, and ease of usage. The everage waiting time of less than 20 seconds with less than 3% waiting rate of more than 60 seconds is accepted as a satisfactory service condition. There are many conflicting matters in group-controlling, and the study for the controlling must deal with the optimization of multi-purpose problems. The standards for group-control evaluation differ according to building structures and the tastes of users, and an important problem is where to give emphasis of the evaluation. The TRAFFIC PATTERN LEARNING METHOD has been applied in the system for careful control to accommodate the traffic. No specific function is provided for the evaluation, but the call allocation is made by fuzzy rule-base. The configuration of a new group-control system is introduced. 7 references, 7 figures, 1 table.

  15. Functional Group Analysis.

    Science.gov (United States)

    Smith, Walter T., Jr.; Patterson, John M.

    1984-01-01

    Literature on analytical methods related to the functional groups of 17 chemical compounds is reviewed. These compounds include acids, acid azides, alcohols, aldehydes, ketones, amino acids, aromatic hydrocarbons, carbodiimides, carbohydrates, ethers, nitro compounds, nitrosamines, organometallic compounds, peroxides, phenols, silicon compounds,…

  16. Moral motivation within groups

    NARCIS (Netherlands)

    Lee, Romy van der

    2013-01-01

    Morality is of particular importance to people: People want to be considered moral and want to belong to moral groups. Consequently, morality judgments have the potential to motivate individuals to behave in ways that are considered to be ‘good’. In the current dissertation, I examined the impact of

  17. Smoot Group Cosmology

    Science.gov (United States)

    the Universe About Cosmology Planck Satellite Launched Cosmology Videos Professor George Smoot's group conducts research on the early universe (cosmology) using the Cosmic Microwave Background radiation (CMB science goals regarding cosmology. George Smoot named Director of Korean Cosmology Institute The GRB

  18. Groups and Symmetry

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. Groups and Symmetry: A Guide to Discovering Mathematics. Geetha Venkataraman. Book Review Volume 4 Issue 10 October 1999 pp 91-92. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Public interest group involvement

    International Nuclear Information System (INIS)

    Shelley, P.

    1986-01-01

    Including public interest groups in the siting process for nuclear waste disposal facilities is of great importance. Controversial sitings often result in litigation, but involving public interest groups early in the process will lessen the change of this. They act as surrogates for the general public and should be considered as members of the team. It is important to remember though, that all public interest groups are different. In choosing public panels such as public advisory committees, members should not be chosen on the basis of some quota. Opposition groups should not be excluded. Also, it is important to put the right person in charge of the committee. The goal of public involvement is to identify the conflicts. This must be done during the decision process, because conflicts must be known before they can be eliminated. Regarding litigation, it is important to ease through and around legal battles. If the siting process has integrity and a good faith effort has been shown, the court should uphold the effort. In addition, it is important to be negotiable and to eliminate shortcuts

  20. Leukosis/Sarcoma Group

    Science.gov (United States)

    The leukosis/sarcoma (L/S) group of diseases designates a variety of transmissible benign and malignant neoplasms of chickens caused by members that belong to the family Retroviridae. Because the expansion of the literature on this disease, it is no longer feasible to cite all relevant publications ...

  1. Working Group Report: Neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    de Gouvea, A.; Pitts, K.; Scholberg, K.; Zeller, G. P. [et al.

    2013-10-16

    This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos.

  2. Group: radiation dosimetry

    International Nuclear Information System (INIS)

    Caldas, L.V.E.

    1990-01-01

    The main activities of the radiation dosimetry group is described, including the calibration of instruments, sources and radioactive solutions and the determination of neutron flux; development, production and market dosimetric materials; development radiation sensor make the control of radiation dose received by IPEN workers; development new techniques for monitoring, etc. (C.G.C.)

  3. Categorization by Groups

    NARCIS (Netherlands)

    R.W. Hamilton (Rebecca); S. Puntoni (Stefano); N.T. Tavassoli (Nader)

    2006-01-01

    textabstractCategorization is a core psychological process central to consumer and managerial decision-making. While a substantial amount of research has been conducted to examine individual categorization behaviors, relatively little is known about the group categorization process. In two

  4. Gamma gamma technology group

    Indian Academy of Sciences (India)

    The purpose of the meeting was to form a group of people who ... able by looking at the energy deposited at the face of the final dipole, 4.5 m from ... A F Zarnecki has made a good start on background studies, V Telnov has proposed.

  5. Group theory in physics

    CERN Document Server

    Cornwell, J F

    1989-01-01

    Recent devopments, particularly in high-energy physics, have projected group theory and symmetry consideration into a central position in theoretical physics. These developments have taken physicists increasingly deeper into the fascinating world of pure mathematics. This work presents important mathematical developments of the last fifteen years in a form that is easy to comprehend and appreciate.

  6. Anaphylaxis vulnerable groups

    African Journals Online (AJOL)

    Ehab

    Age groups vulnerable to serious attacks of anaphylaxis include infants, teenagers, pregnant women, and the elderly. Concomitant diseases, such as severe or uncontrolled asthma, cardiovascular disease, mastocytosis or clonal mast cell disorders and the concurrent use of some medications such as beta adrenergic ...

  7. Special Interest Groups.

    Science.gov (United States)

    Degi, Bruce J.

    1999-01-01

    Offers a reflection on the shootings at Columbine High School in Littleton, Colorado, on April 20, 1999. Notes how every special-interest group has used the tragedy to support its own point of view, and concludes that teachers have become bystanders in the education of America's children. (SR)

  8. Ignalina Safety Analysis Group

    International Nuclear Information System (INIS)

    Ushpuras, E.

    1995-01-01

    The article describes the fields of activities of Ignalina NPP Safety Analysis Group (ISAG) in the Lithuanian Energy Institute and overview the main achievements gained since the group establishment in 1992. The group is working under the following guidelines: in-depth analysis of the fundamental physical processes of RBMK-1500 reactors; collection, systematization and verification of the design and operational data; simulation and analysis of potential accident consequences; analysis of thermohydraulic and neutronic characteristics of the plant; provision of technical and scientific consultations to VATESI, Governmental authorities, and also international institutions, participating in various projects aiming at Ignalina NPP safety enhancement. The ISAG is performing broad scientific co-operation programs with both Eastern and Western scientific groups, supplying engineering assistance for Ignalina NPP. ISAG is also participating in the joint Lithuanian - Swedish - Russian project - Barselina, the first Probabilistic Safety Assessment (PSA) study of Ignalina NPP. The work is underway together with Maryland University (USA) for assessment of the accident confinement system for a range of breaks in the primary circuit. At present the ISAG personnel is also involved in the project under the grant from the Nuclear Safety Account, administered by the European Bank for reconstruction and development for the preparation and review of an in-depth safety assessment of the Ignalina plant

  9. Gartner Group reports

    CERN Document Server

    Gartner Group. Stamford, CT

    Gartner Group is the one of the leading independent providers of research and analysis material for IT professionals. Their reports provide in-depth analysis of dominant trends, companies and products. CERN has obtained a licence making these reports available online to anyone within CERN. The database contains not only current reports, updated monthly, but also some going back over a year.

  10. Lattices in group manifolds

    International Nuclear Information System (INIS)

    Lisboa, P.; Michael, C.

    1982-01-01

    We address the question of designing optimum discrete sets of points to represent numerically a continuous group manifold. We consider subsets which are extensions of the regular discrete subgroups. Applications to Monte Carlo simulation of SU(2) and SU(3) gauge theory are discussed. (orig.)

  11. Teaching Badminton to Groups.

    Science.gov (United States)

    Nelson, Jonathan E.

    1980-01-01

    Numerous ideas for teaching badminton to large groups are presented. The focus is on drills and techniques for off the court instructional stations. Instead of having students waiting their turn to play, more students can participate actively as they rotate from one station to another. (JN)

  12. Group leaders optimization algorithm

    Science.gov (United States)

    Daskin, Anmer; Kais, Sabre

    2011-03-01

    We present a new global optimization algorithm in which the influence of the leaders in social groups is used as an inspiration for the evolutionary technique which is designed into a group architecture. To demonstrate the efficiency of the method, a standard suite of single and multi-dimensional optimization functions along with the energies and the geometric structures of Lennard-Jones clusters are given as well as the application of the algorithm on quantum circuit design problems. We show that as an improvement over previous methods, the algorithm scales as N 2.5 for the Lennard-Jones clusters of N-particles. In addition, an efficient circuit design is shown for a two-qubit Grover search algorithm which is a quantum algorithm providing quadratic speedup over the classical counterpart.

  13. Communication from ST Group

    CERN Document Server

    TS Department

    2008-01-01

    Please note that owing the preparations for the Open Days, the FM Group will not able to handle specific requests for waste collection from 2nd to 6th of April, nor removal or PC transport requests between the 31 March and 11 April. We kindly ask you to plan the collection of all types of waste and any urgent transport of office furniture or PCs before 31 March. Waste collection requests must be made by contacting FM Support on 77777 or at the e-mail address mailto:Fm.Support@cern.ch; removal of office furniture or PC transport requests must be made using the EDH ‘Transport request’ form (select "Removals" or "PC transport" from the drop-down menu). For any question concerning the sorting of waste, please consult the following web site: http://dechets-waste.web.cern.ch/dechets-waste/ Thank you for your understanding and collaboration. TS/FM Group

  14. Mindfulness for group facilitation

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine; Krohn, Simon

    2014-01-01

    In this paper, we argue that mindfulness techniques can be used for enhancing the outcome of group performance. The word mindfulness has different connotations in the academic literature. Broadly speaking there is ‘mindfulness without meditation’ or ‘Western’ mindfulness which involves active...... thinking and ‘Eastern’ mindfulness which refers to an open, accepting state of mind, as intended with Buddhist-inspired techniques such as meditation. In this paper, we are interested in the latter type of mindfulness and demonstrate how Eastern mindfulness techniques can be used as a tool for facilitation....... A brief introduction to the physiology and philosophy of Eastern mindfulness constitutes the basis for the arguments of the effect of mindfulness techniques. The use of mindfulness techniques for group facilitation is novel as it changes the focus from individuals’ mindfulness practice...

  15. Group and representation theory

    CERN Document Server

    Vergados, J D

    2017-01-01

    This volume goes beyond the understanding of symmetries and exploits them in the study of the behavior of both classical and quantum physical systems. Thus it is important to study the symmetries described by continuous (Lie) groups of transformations. We then discuss how we get operators that form a Lie algebra. Of particular interest to physics is the representation of the elements of the algebra and the group in terms of matrices and, in particular, the irreducible representations. These representations can be identified with physical observables. This leads to the study of the classical Lie algebras, associated with unitary, unimodular, orthogonal and symplectic transformations. We also discuss some special algebras in some detail. The discussion proceeds along the lines of the Cartan-Weyl theory via the root vectors and root diagrams and, in particular, the Dynkin representation of the roots. Thus the representations are expressed in terms of weights, which are generated by the application of the elemen...

  16. Working group 4: Terrestrial

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    A working group at a Canada/USA symposium on climate change and the Arctic identified major concerns and issues related to terrestrial resources. The group examined the need for, and the means of, involving resource managers and users at local and territorial levels in the process of identifying and examining the impacts and consequences of climatic change. Climatic change will be important to the Arctic because of the magnitude of the change projected for northern latitudes; the apparent sensitivity of its terrestrial ecosystems, natural resources, and human support systems; and the dependence of the social, cultural, and economic welfare of Arctic communities, businesses, and industries on the health and quality of their environment. Impacts of climatic change on the physical, biological, and associated socio-economic environment are outlined. Gaps in knowledge needed to quantify these impacts are listed along with their relationships with resource management. Finally, potential actions for response and adaptation are presented

  17. Duality and quantum groups

    International Nuclear Information System (INIS)

    Alvarez-Gaume, L.; Gomez, C.; Sierra, G.

    1990-01-01

    We show that the duality properties of Rational Conformal Field Theories follow from the defining relations and the representation theory of quantum groups. The fusion and braiding matrices are q-analogues of the 6j-symbols and the modular transformation matrices are obtained from the properties of the co-multiplication. We study in detail the Wess-Zumino-Witten models and the rational gaussian models as examples, but carry out the arguments in general. We point out the connections with the Chern-Simons approach. We give general arguments of why the general solution to the polynomial equations of Moore and Seiberg describing the duality properties of Rational Conformal Field Theories defines a Quantum Group acting on the space of conformal blocks. A direct connection between Rational Theories and knot invariants is also presented along the lines of Jones' original work. (orig.)

  18. The Areva Group

    International Nuclear Information System (INIS)

    2004-08-01

    This document provides information on the Areva Group, a world nuclear industry leader, offering solutions for nuclear power generation, electricity transmission and distribution and interconnect systems to the telecommunications, computer and automotive markets. It presents successively the front end division including the group business lines involved in producing nuclear fuel for electric power generation (uranium mining, concentration, conversion and enrichment and nuclear fuel fabrication); the reactors and services division which designs and builds PWR, BWR and research reactors; the back end division which encompasses the management of the fuel that has been used in nuclear power plants; the transmission and distribution division which provides products, systems and services to the medium and high voltage energy markets; the connectors division which designs and manufactures electrical, electronic and optical connectors, flexible micro circuitry and interconnection systems. Areva is implemented in Europe, north and south america, africa and asia-pacific. (A.L.B.)

  19. The Ombudperson Initiative Group

    CERN Multimedia

    Laura Stewart

    Following many discussions that took place at some of the ATLAS Women's Network lunch gatherings, a few ATLAS women joined forces with similarly concerned CERN staff women to form a small group last Fall to discuss the need for a CERN-wide Ombudsperson. This has since evolved into the Ombudsperson Initiative Group (OIG) currently composed of the following members: Barbro Asman, Stockholm University; Pierre Charrue, CERN AB; Anna Cook, CERN IT; Catherine Delamare, CERN and IT Ombudsperson; Paula Eerola, Lund University; Pauline Gagnon, Indiana University; Eugenia Hatziangeli, CERN AB; Doreen Klem, CERN IT; Bertrand Nicquevert, CERN TS and Laura Stewart, CERN AT. On June 12, members of the OIG met with representatives of Human Resources (HR) and the Equal Opportunity Advisory Panel (EOAP) to discuss the proposal drafted by the OIG. The meeting was very positive. Everybody agreed that the current procedures at CERN applicable in the event of conflict required a thorough review, and that a professionnally trai...

  20. Metrically universal abelian groups

    Czech Academy of Sciences Publication Activity Database

    Doucha, Michal

    2017-01-01

    Roč. 369, č. 8 (2017), s. 5981-5998 ISSN 0002-9947 R&D Projects: GA AV ČR IAA100190902 Institutional support: RVO:67985840 Keywords : Abelian group Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.426, year: 2016 http://www.ams.org/journals/tran/2017-369-08/S0002-9947-2017-07059-8/

  1. Storage ring group summary

    International Nuclear Information System (INIS)

    King, N.M.

    1980-01-01

    The Storage Ring Group set out to identify and pursue salient problems in accelerator physics for heavy ion fusion, divorced from any particular reference design concept. However, it became apparent that some basic parameter framework was required to correlate the different study topics. As the Workshop progressed, ring parameters were modified and updated. Consequently, the accompanying papers on individual topics will be found to refer to slightly varied parameters, according to the stage at which the different problems were tackled

  2. MAGIC user's group software

    International Nuclear Information System (INIS)

    Warren, G.; Ludeking, L.; McDonald, J.; Nguyen, K.; Goplen, B.

    1990-01-01

    The MAGIC User's Group has been established to facilitate the use of electromagnetic particle-in-cell software by universities, government agencies, and industrial firms. The software consists of a series of independent executables that are capable of inter-communication. MAGIC, SOS, μ SOS are used to perform electromagnetic simulations while POSTER is used to provide post-processing capabilities. Each is described in the paper. Use of the codes for Klystrode simulation is discussed

  3. Multibunch working group

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The goal of this working group was to foment discussions about the use and limitations of multi-bunch, representatives from most operating or in-project synchrotron radiation sources (ALS, SPEAR, BESSY-2, SPRING-8, ANKA, DELTA, PEP-2, DIAMOND, ESRF...) have presented their experience. The discussions have been led around 3 topics: 1) resistive wall instabilities and ion instabilities, 2) higher harmonic cavities, and 3) multibunch feedback systems.

  4. Group 4. Containment

    International Nuclear Information System (INIS)

    McCauley, V.S.; Keiser, J.R.

    1992-01-01

    This paper summarizes the findings of the Containment Working Group which met at the Workshop on Radioactive, Hazardous, and/or Mixed Waste Sludge Management. The Containment Working Group (CWG) examined the problems associated with providing adequate containment of waste forms from both short- and long-term storage. By its nature, containment encompasses a wide variety of waste forms, storage conditions, container types, containment schemes, and handling activities. A containment system can be anything from a 55-gal drum to a 100-ft-long underground vault. Because of the diverse nature of containment systems, the CWG chose to focus its limited time on broad issues that are applicable to the design of any containment system, rather than attempting to address problems specific to a particular containment system or waste-form type. Four major issues were identified by the CWG. They relate to: (1) service conditions and required system performance; (2) ultimate disposition; (3) cost and schedule; and (4) acceptance criteria, including quality assurance/quality control (QA/QC) concerns. All of the issues raised by the group are similar in that they all help to define containment system requirements

  5. Technology working group

    International Nuclear Information System (INIS)

    Tsujikura, Y.

    2000-01-01

    The workshop of 26-27 june 2000, on nuclear power Plant LIfe Management (PLIM), also included working groups in which major issues facing PLIM activities for nuclear power plants were identified and discussed. The first group was on Technology. Utilities should consider required provisions capacity by properly maintaining and preserving the existing power plants to the extent practicable and taking into account growing demand, limits of energy conservation, and difficulties in finding new power plant sites. Generally, the extension of the life of nuclear power plant (e.g. from 40 years to 60 years) is an attractive option for utilities, as the marginal cost of most existing nuclear power plants is lower than that of almost all other power sources. It is also an attractive option for environmental protection. Consequently, PLIM has become an important issue in the context of the regulatory reform of the electricity markets. Therefore, the three main objectives of the Technology working group are: 1) Documenting how the safety of nuclear power plants being operated for the long-term has been confirmed, and suggesting ways of sharing this information. 2) Addressing development of advanced maintenance technologies necessary over the plant lifetime, and clarifying their technical challenges. 3) Suggesting potential areas of research and development that might, be necessary. Some potential examples of such research include: - improving the effectiveness of maintenance methods to assure detection of incipient faults; - providing cost effective preventive maintenance programmes; - furnishing systematic, cost-effective refurbishment programmes framed to be consistent with efforts to extend the time between re-fuelling; - developing a methodology that moves routine maintenance on-line without compromising safety. (author)

  6. Notes on quantum groups

    International Nuclear Information System (INIS)

    Pressley, A.; Chari, V.; Tata Inst. of Fundamental Research, Bombay

    1990-01-01

    The authors presents an introduction to quantum groups defined as a deformation of the universal enveloping algebra of a Lie algebra. After the description of Hopf algebras with some examples the approach of Drinfel'd and Jimbo is described, where the quantization of a Lie algebra represents a Hopf algebra, defined over the algebra of formal power series in an indetermined h. The authors show that this approach arises from a r-matrix, which satisfies the classical Yang-Baxter equation. As example quantum sl 2 is considered. Furthermore the approaches of Manin and Woroniwicz and the R-matrix approach are described. (HSI)

  7. Unilever Group : equity valuation

    OpenAIRE

    Pires, Susana Sofia Castelo

    2014-01-01

    The following dissertation has the purpose to value the Unilever Group, but more specifically Unilever N.V. being publicly traded in the Amsterdam Exchange Index. Unilever is seen as a global player and one of most successful and competitive fast-moving consumer goods companies. In order to valuate Unilever’s equity, a Discounted Cash Flow (DCF) approach is first carried out, since it is believed to be the most reliable methodology. The value estimated was €36.39, advising one to buy its s...

  8. Statistical Group Comparison

    CERN Document Server

    Liao, Tim Futing

    2011-01-01

    An incomparably useful examination of statistical methods for comparisonThe nature of doing science, be it natural or social, inevitably calls for comparison. Statistical methods are at the heart of such comparison, for they not only help us gain understanding of the world around us but often define how our research is to be carried out. The need to compare between groups is best exemplified by experiments, which have clearly defined statistical methods. However, true experiments are not always possible. What complicates the matter more is a great deal of diversity in factors that are not inde

  9. Renormalization Group Functional Equations

    CERN Document Server

    Curtright, Thomas L

    2011-01-01

    Functional conjugation methods are used to analyze the global structure of various renormalization group trajectories. With minimal assumptions, the methods produce continuous flows from step-scaling {\\sigma} functions, and lead to exact functional relations for the local flow {\\beta} functions, whose solutions may have novel, exotic features, including multiple branches. As a result, fixed points of {\\sigma} are sometimes not true fixed points under continuous changes in scale, and zeroes of {\\beta} do not necessarily signal fixed points of the flow, but instead may only indicate turning points of the trajectories.

  10. Grouping Notes Through Nodes

    DEFF Research Database (Denmark)

    Dove, Graham; Abildgaard, Sille Julie Jøhnk; Biskjær, Michael Mose

    , both individually and when grouped, and their role in categorisation in semantic long-term memory. To do this, we adopt a multimodal analytical approach focusing on interaction between humans, and between humans and artefacts, alongside language. We discuss in detail examples of four different...... externalisation functions served by Post-ItTM notes, and show how these functions are present in complex overlapping combinations rather than being discrete. We then show how the temporal development of Post-ItTM note interactions supports categorisation qualities of semantic long-term memory....

  11. Grouping Notes Through Nodes

    DEFF Research Database (Denmark)

    Dove, Graham; Abildgaard, Sille Julie; Biskjær, Michael Mose

    2017-01-01

    , both individually and when grouped, and their role in categorisation in semantic long-term memory. To do this, we adopt a multimodal analytical approach focusing on interaction between humans, and between humans and artefacts, alongside language. We discuss in detail examples of four different...... externalisation functions served by Post-ItTM notes, and show how these functions are present in complex overlapping combinations rather than being discrete. We then show how the temporal development of Post-ItTM note interactions supports categorisation qualities of semantic long-term memory....

  12. Groups and symmetry

    CERN Document Server

    Farmer, David W

    1995-01-01

    In most mathematics textbooks, the most exciting part of mathematics-the process of invention and discovery-is completely hidden from the reader. The aim of Groups and Symmetry is to change all that. By means of a series of carefully selected tasks, this book leads readers to discover some real mathematics. There are no formulas to memorize; no procedures to follow. The book is a guide: Its job is to start you in the right direction and to bring you back if you stray too far. Discovery is left to you. Suitable for a one-semester course at the beginning undergraduate level, there are no prerequ

  13. Theory and modeling group

    Science.gov (United States)

    Holman, Gordon D.

    1989-01-01

    The primary purpose of the Theory and Modeling Group meeting was to identify scientists engaged or interested in theoretical work pertinent to the Max '91 program, and to encourage theorists to pursue modeling which is directly relevant to data which can be expected to result from the program. A list of participants and their institutions is presented. Two solar flare paradigms were discussed during the meeting -- the importance of magnetic reconnection in flares and the applicability of numerical simulation results to solar flare studies.

  14. The OMERACT Ultrasound Group

    DEFF Research Database (Denmark)

    Terslev, Lene; Iagnocco, Annamaria; Bruyn, George A W

    2017-01-01

    OBJECTIVE: To provide an update from the Outcome Measures in Rheumatology (OMERACT) Ultrasound Working Group on the progress for defining ultrasound (US) minimal disease activity threshold at joint level in rheumatoid arthritis (RA) and for standardization of US application in juvenile idiopathic......) and power Doppler (PD). Synovial effusion (SE) was scored a binary variable. For JIA, a Delphi approach and subsequent validation in static images and patient-based exercises were used to developed preliminary definitions for synovitis and a scoring system. RESULTS: For minimal disease activity, 7% HC had...

  15. A village group, Trashibiola

    OpenAIRE

    Thomson, John, 1837-1921, photographer

    2003-01-01

    158 x 111 mm. Woodburytype. A view showing a group of villagers seated in a paved courtyard in front of a stonewalled house (the principal house in the village). The village is near the town of Paphos. The photograph appears in Thomson's 'Through Cyprus with the camera, in the autumn of 1878' (vol.2, London: Sampson Low, Marston, Searle, and Rivington, 1879). Thomson states that the purpose of the gathering was twofold: to welcome strangers to the village and to discuss a point of law c...

  16. Bevalac computer support group

    International Nuclear Information System (INIS)

    McParland, C.; Bronson, M.

    1985-01-01

    During the past year, a group was created and placed under the leadership of Charles McParland. This is an expansion of previous Bevalac software efforts and has responsibilities in three major hardware and software areas. The first area is the support of the existing data acquisition/analysis VAX 11/780s at the Bevalac. The second area is the continued support of present data acquisition programs. The third principal area of effort is the development of new data acquisition systems to meet the increasing needs of the Bevalac experimental program

  17. Social group utility maximization

    CERN Document Server

    Gong, Xiaowen; Yang, Lei; Zhang, Junshan

    2014-01-01

    This SpringerBrief explains how to leverage mobile users' social relationships to improve the interactions of mobile devices in mobile networks. It develops a social group utility maximization (SGUM) framework that captures diverse social ties of mobile users and diverse physical coupling of mobile devices. Key topics include random access control, power control, spectrum access, and location privacy.This brief also investigates SGUM-based power control game and random access control game, for which it establishes the socially-aware Nash equilibrium (SNE). It then examines the critical SGUM-b

  18. ATLAS Detector Interface Group

    CERN Multimedia

    Mapelli, L

    Originally organised as a sub-system in the DAQ/EF-1 Prototype Project, the Detector Interface Group (DIG) was an information exchange channel between the Detector systems and the Data Acquisition to provide critical detector information for prototype design and detector integration. After the reorganisation of the Trigger/DAQ Project and of Technical Coordination, the necessity to provide an adequate context for integration of detectors with the Trigger and DAQ lead to organisation of the DIG as one of the activities of Technical Coordination. Such an organisation emphasises the ATLAS wide coordination of the Trigger and DAQ exploitation aspects, which go beyond the domain of the Trigger/DAQ project itself. As part of Technical Coordination, the DIG provides the natural environment for the common work of Trigger/DAQ and detector experts. A DIG forum for a wide discussion of all the detector and Trigger/DAQ integration issues. A more restricted DIG group for the practical organisation and implementation o...

  19. Communication from ST Group

    CERN Multimedia

    TS Department

    2008-01-01

    In order to prepare the organization of the Open Days, please note that FM Group will not able to take into account either specific requests for waste collection from 2nd to 6th of April, either removal or PC transport requests between the 31st and the 11th of March. We kindly ask you to plan the collection of any type of waste and the urgent transport of office furniture or PC before the 31st of March. Waste collection requests shall be formulated contacting FM Support at 77777 or at the email address mailto:Fm.Support@cern.ch; removal of office furniture or PC transport requests must be made using the EDH ‘Transport request’ form selecting the "Removals" or the "PC transport" category from the drop-down menu. For any question concerning the waste sorting, please consult the following web address: http://dechets-waste.web.cern.ch/dechets-waste/. Thank you for your understanding and collaboration. TS/FM Group

  20. Social group and mobbing

    Directory of Open Access Journals (Sweden)

    Baltezarević Vesna

    2009-01-01

    Full Text Available Our reality, having been subject to the numerous social crises during the last decades of the 20th century, is characterized by frequent incidences of powerlessness and alienation. The man is more frequently a subject to loneliness and overcomes the feeling of worthlessness, no matter whether he considers himself an individual or a part of a whole larger social. Such an environment leads to development of aggression in all fields of ones life. This paper has as an objective the pointing out of the mental harassment that is manifested in the working environment. There is a prevalence of mobbing cases, as a mode of pathological communication. The result of this is that a person, subjected to this kind of abuse, is soon faced with social isolation. This research also aspires to initiate the need for social groups self-organization of which victims are part of. The reaction modality of a social group directly conditions the outcome of the deliberate social drama, one is subjected to it as a result of mobbing.

  1. Meningococcal group B vaccines.

    Science.gov (United States)

    Findlow, Jamie

    2013-06-01

    Meningococcal disease remains a devastating and feared infection with a significant morbidity and mortality profile. The successful impact of meningococcal capsular group C glyconconjugate vaccines introduced into the UK infant immunization schedule in 1999, has resulted in >80% of disease now being attributable to meningococcal capsular group B (MenB). MenB glyconconjugate vaccines are not immunogenic and hence, vaccine design has focused on sub-capsular antigens. Recently, a four component vaccine to combat MenB disease (4CMenB) has progressed through clinical development and was approved by the European Medicines Agency at the end of 2012. This vaccine has proven safe and immunogenic and has been predicted to provide protection against ~73% of the MenB disease from England and Wales. Recommendation/implementation of the vaccine into the UK infant schedule is currently being evaluated. 4CMenB has the potential to provide protection against a significant proportion of MenB disease in the UK which is currently unpreventable.

  2. Business working group

    International Nuclear Information System (INIS)

    Doroshuk, B.W.

    2000-01-01

    The workshop of 26-27 june 2000, on nuclear power Plant LIfe Management (PLIM), also included working groups in which major issues facing PLIM activities for nuclear power plants were identified and discussed. The third group was on Business. The discussion concerned the following points: There are concerns about retaining experienced/trained personnel, and maintaining a good working relationship among them, as well as about the closure of research facilities, the reduction in staff numbers under increasing economic pressure and the lack of new nuclear power plant constructions. The marginal cost of producing electricity is lower for most existing nuclear power plants than for almost all other energy sources. Refurbishment costs are usually relatively small compared with new investments. The ongoing regulatory reform of the electricity market will bring increasing competition. Although PLIM has been carried out in many countries with favourable results, there are still uncertainties which affect business decisions regarding financial and market risks in PLIM activities. Recommendations were made. (author)

  3. Group Life Insurance

    CERN Multimedia

    2013-01-01

    The CERN Administration would like to remind you that staff members and fellows have the possibility to take out a life insurance contract on favourable terms through a Group Life Insurance.   This insurance is provided by the company Helvetia and is available to you on a voluntary basis. The premium, which varies depending on the age and gender of the person insured, is calculated on the basis of the amount of the death benefit chosen by the staff member/fellow and can be purchased in slices of 10,000 CHF.    The contract normally ends at the retirement age (65/67 years) or when the staff member/fellow leaves the Organization. The premium is deducted monthly from the payroll.   Upon retirement, the staff member can opt to maintain his membership under certain conditions.   More information about Group Life Insurance can be found at: Regulations (in French) Table of premiums The Pension Fund Benefit Service &...

  4. On the Brauer group

    International Nuclear Information System (INIS)

    Tankeev, Sergei G

    2000-01-01

    For an arithmetic model X of a Fermat surface or a hyperkahler variety with Betti number b 2 (V otimes k-bar)>3 over a purely imaginary number field k, we prove the finiteness of the l-components of Br'(X) for all primes l>>0. This yields a variant of a conjecture of M. Artin. If V is a smooth projective irregular surface over a number field k and V(k)≠ nothing, then the l-primary component of Br(V)/Br(k) is an infinite group for every prime l. Let A 1 →M 1 be the universal family of elliptic curves with a Jacobian structure of level N>=3 over a number field k supset of Q(e 2πi/N ). Assume that M 1 (k) ≠ nothing. If V is a smooth projective compactification of the surface A 1 , then the l-primary component of Br(V)/Br(M-bar 1 ) is a finite group for each sufficiently large prime l

  5. Biology task group

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    The accomplishments of the task group studies over the past year are reviewed. The purposes of biological investigations, in the context of subseabed disposal, are: an evaluation of the dose to man; an estimation of effects on the ecosystem; and an estimation of the influence of organisms on and as barriers to radionuclide migration. To accomplish these ends, the task group adopted the following research goals: (1) acquire more data on biological accumulation of specific radionuclides, such as those of Tc, Np, Ra, and Sr; (2) acquire more data on transfer coefficients from sediment to organism; (3) Calculate mass transfer rates, construct simple models using them, and estimate collective dose commitment; (4) Identify specific pathways or transfer routes, determine the rates of transfer, and make dose limit calculations with simple models; (5) Calculate dose rates to and estimate irradiation effects on the biota as a result of waste emplacement, by reference to background irradiation calculations. (6) Examine the effect of the biota on altering sediment/water radionuclide exchange; (7) Consider the biological data required to address different accident scenarios; (8) Continue to provide the basic biological information for all of the above, and ensure that the system analysis model is based on the most realistic and up-to-date concepts of marine biologists; and (9) Ensure by way of free exchange of information that the data used in any model are the best currently available

  6. Doing focus group research

    DEFF Research Database (Denmark)

    Lindegaard, Laura Bang

    2014-01-01

    Scholars of ethnomethodologically informed discourse studies are often sceptical of the use of interview data such as focus group data. Some scholars quite simply reject interview data with reference to a general preference for so-called naturally occurring data. Other scholars acknowledge...... that interview data can be of some use if the distinction between natural and contrived data is given up and replaced with a distinction between interview data as topic or as resource. In greater detail, such scholars argue that interview data are perfectly adequate if the researcher wants to study the topic...... of interview interaction, but inadequate as data for studying phenomena that go beyond the phenomenon of interview interaction. Neither of these more and less sceptical positions are, on the face of it, surprising due to the ethnomethodological commitment to study social order as accomplished in situ...

  7. Group life insurance

    CERN Multimedia

    2013-01-01

    The CERN Administration wishes to inform staff members and fellows having taken out optional life insurance under the group contract signed by CERN that the following changes to the rules and regulations entered into force on 1 January 2013:   The maximum age for an active member has been extended from 65 to 67 years. The beneficiary clause now allows insured persons to designate one or more persons of their choice to be their beneficiary(-ies), either at the time of taking out the insurance or at a later date, in which case the membership/modification form must be updated accordingly. Beneficiaries must be clearly identified (name, first name, date of birth, address).   The membership/modification form is available on the FP website: http://fp.web.cern.ch/helvetia-life-insurance For further information, please contact: Valentina Clavel (Tel. 73904) Peggy Pithioud (Tel. 72736)

  8. End Group Modification

    DEFF Research Database (Denmark)

    Jahnsen, Rasmus O; Sandberg-Schaal, Anne; Frimodt-Møller, Niels

    2015-01-01

    Increased incidence of infections with multidrug-resistant bacterial strains warrants an intensive search for novel potential antimicrobial agents. Here, an antimicrobial peptide analogue with a cationic/hydrophobic alternating design displaying only moderate activity against Gram-positive pathog......Increased incidence of infections with multidrug-resistant bacterial strains warrants an intensive search for novel potential antimicrobial agents. Here, an antimicrobial peptide analogue with a cationic/hydrophobic alternating design displaying only moderate activity against Gram......, the most favorable hydrophobic activity-inducing moieties were found to be cyclohexylacetyl and pentafluorophenylacetyl groups, while the presence of a short PEG-like chain had no significant effect on activity. Introduction of cationic moieties conferred no effect or merely a moderate activity...

  9. Optimised Renormalisation Group Flows

    CERN Document Server

    Litim, Daniel F

    2001-01-01

    Exact renormalisation group (ERG) flows interpolate between a microscopic or classical theory and the corresponding macroscopic or quantum effective theory. For most problems of physical interest, the efficiency of the ERG is constrained due to unavoidable approximations. Approximate solutions of ERG flows depend spuriously on the regularisation scheme which is determined by a regulator function. This is similar to the spurious dependence on the ultraviolet regularisation known from perturbative QCD. Providing a good control over approximated ERG flows is at the root for reliable physical predictions. We explain why the convergence of approximate solutions towards the physical theory is optimised by appropriate choices of the regulator. We study specific optimised regulators for bosonic and fermionic fields and compare the optimised ERG flows with generic ones. This is done up to second order in the derivative expansion at both vanishing and non-vanishing temperature. An optimised flow for a ``proper-time ren...

  10. Graphs, groups and surfaces

    CERN Document Server

    White, AT

    1985-01-01

    The field of topological graph theory has expanded greatly in the ten years since the first edition of this book appeared. The original nine chapters of this classic work have therefore been revised and updated. Six new chapters have been added, dealing with: voltage graphs, non-orientable imbeddings, block designs associated with graph imbeddings, hypergraph imbeddings, map automorphism groups and change ringing.Thirty-two new problems have been added to this new edition, so that there are now 181 in all; 22 of these have been designated as ``difficult'''' and 9 as ``unsolved''''. Three of the four unsolved problems from the first edition have been solved in the ten years between editions; they are now marked as ``difficult''''.

  11. Quantum Secure Group Communication.

    Science.gov (United States)

    Li, Zheng-Hong; Zubairy, M Suhail; Al-Amri, M

    2018-03-01

    We propose a quantum secure group communication protocol for the purpose of sharing the same message among multiple authorized users. Our protocol can remove the need for key management that is needed for the quantum network built on quantum key distribution. Comparing with the secure quantum network based on BB84, we show our protocol is more efficient and securer. Particularly, in the security analysis, we introduce a new way of attack, i.e., the counterfactual quantum attack, which can steal information by "invisible" photons. This invisible photon can reveal a single-photon detector in the photon path without triggering the detector. Moreover, the photon can identify phase operations applied to itself, thereby stealing information. To defeat this counterfactual quantum attack, we propose a quantum multi-user authorization system. It allows us to precisely control the communication time so that the attack can not be completed in time.

  12. Working Group Report: Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Artuso, M.; et al.,

    2013-10-18

    Sensors play a key role in detecting both charged particles and photons for all three frontiers in Particle Physics. The signals from an individual sensor that can be used include ionization deposited, phonons created, or light emitted from excitations of the material. The individual sensors are then typically arrayed for detection of individual particles or groups of particles. Mounting of new, ever higher performance experiments, often depend on advances in sensors in a range of performance characteristics. These performance metrics can include position resolution for passing particles, time resolution on particles impacting the sensor, and overall rate capabilities. In addition the feasible detector area and cost frequently provides a limit to what can be built and therefore is often another area where improvements are important. Finally, radiation tolerance is becoming a requirement in a broad array of devices. We present a status report on a broad category of sensors, including challenges for the future and work in progress to solve those challenges.

  13. Representation Theory of Algebraic Groups and Quantum Groups

    CERN Document Server

    Gyoja, A; Shinoda, K-I; Shoji, T; Tanisaki, Toshiyuki

    2010-01-01

    Invited articles by top notch expertsFocus is on topics in representation theory of algebraic groups and quantum groupsOf interest to graduate students and researchers in representation theory, group theory, algebraic geometry, quantum theory and math physics

  14. PEP magnet power supply systems

    International Nuclear Information System (INIS)

    Jackson, L.T.

    1977-01-01

    The dc electrical requirements of the PEP magnets fall mainly into two categories: (1) high power and current of single polarity and (2) low-power bi-polar. The first category will be thyristor-chopper controlled off common 600 V dc busses. The second group will utilize continuously controlled push-pull transistor actuators

  15. Oklo working group meeting

    International Nuclear Information System (INIS)

    Von Maravic, H.

    1993-01-01

    Natural analogue studies have been carried out for several years in the framework of the European Community's R and D programme on radioactive waste; and within its recent fourth five-year programme on 'Management and storage of radioactive waste (1990-94)' the Community is participating in the Oklo study, natural analogue for transfer processes in a geological repository. The Oklo project is coordinated by CEA-IPSN (F) and involves laboratories from several CEA directorates (IPSN, DTA and DCC) which collaborate with other institutions from France: CREGU, Nancy; CNRS, Strasbourg and ENSMD, Fontainebleau. Moreover, institutes from non-EC member States are also taking part in the Oklo study. The second joint CEC-CEA progress meeting of the Oklo Working Group was held in April 1992 in Brussels and gave the possibility of reviewing and discussing progress made since its first meeting in February 1991 at CEA in Fontenay-aux-Roses. About 40 participants from 15 laboratories and organizations coming from France, Canada, Gabon, Japan, Sweden and the USA underline the great interest in the ongoing research activities. The meeting focused on the different tasks within the CEC-CEA Oklo project concerning (i) field survey and sampling, (ii) characterization of the source term, (iii) studies of the petrographical and geochemical system, and (iv) studies of the hydrogeological system and hydrodynamic modelling. (author) 17 papers are presented

  16. The Liabilities Management Group

    International Nuclear Information System (INIS)

    Whitehead, A.W.

    1998-01-01

    The Liabilities Management Group (LMG) was initiated by DTI. It is a cooperative forum which was set up in 1995. The current participants are DTI, UKAEA, NLM (for BNFL), MOD and Magnox Electric. The LMG was initiated to produce closer cooperation between public sector liability management organizations, achieve more cost-effective management of UK nuclear liabilities and enhance development of the UK nuclear decommissioning and waste management strategy. The objectives are to compare practices between liabilities management organizations discuss the scope for collaboration identify priority areas for possible collaboration agree action plans for exploring and undertaking such collaboration.Four task forces have been formed to look at specific areas (R and D, safety, contracts, and project management) and each reports separately to the LMG. The LMG has achieved its original aim of bringing together those with public sector liability management responsibilities. All participants feel that the LMG has been useful and that it should continue. Looking to the future, there is a continuing need for the LMG to facilitate removal of barriers to the achievement of best value for money. The LMG might also consider addressing the 'business process' elements that a liability management organization must be good at in order to define best practice in these. (author)

  17. CORRELATION BETWEEN GROUP LOCAL DENSITY AND GROUP LUMINOSITY

    Energy Technology Data Exchange (ETDEWEB)

    Deng Xinfa [School of Science, Nanchang University, Jiangxi 330031 (China); Yu Guisheng [Department of Natural Science, Nanchang Teachers College, Jiangxi 330103 (China)

    2012-11-10

    In this study, we investigate the correlation between group local number density and total luminosity of groups. In four volume-limited group catalogs, we can conclude that groups with high luminosity exist preferentially in high-density regions, while groups with low luminosity are located preferentially in low-density regions, and that in a volume-limited group sample with absolute magnitude limit M{sub r} = -18, the correlation between group local number density and total luminosity of groups is the weakest. These results basically are consistent with the environmental dependence of galaxy luminosity.

  18. Group Counseling in the Schools

    Science.gov (United States)

    Perusse, Rachelle; Goodnough, Gary E.; Lee, Vivian V.

    2009-01-01

    Group counseling is an effective intervention when working in a school setting. In this article, the authors discuss the different kinds of groups offered in schools, types of group interventions, strategies to use in forming groups, and how to collaborate with others in the school. Because leading groups in schools is a specialized skill, the…

  19. Naive Theories of Social Groups

    Science.gov (United States)

    Rhodes, Marjorie

    2012-01-01

    Four studies examined children's (ages 3-10, Total N = 235) naive theories of social groups, in particular, their expectations about how group memberships constrain social interactions. After introduction to novel groups of people, preschoolers (ages 3-5) reliably expected agents from one group to harm members of the other group (rather than…

  20. Making Cooperative Learning Groups Work.

    Science.gov (United States)

    Hawley, James; De Jong, Cherie

    1995-01-01

    Discusses the use of cooperative-learning groups with middle school students. Describes cooperative-learning techniques, including group roles, peer evaluation, and observation and monitoring. Considers grouping options, including group size and configuration, dyads, the think-pair-share lecture, student teams achievement divisions, jigsaw groups,…

  1. Fermilab Steering Group Report

    Energy Technology Data Exchange (ETDEWEB)

    Beier, Eugene; /Pennsylvania U.; Butler, Joel; /Fermilab; Dawson, Sally; /Brookhaven; Edwards, Helen; /Fermilab; Himel, Thomas; /SLAC; Holmes, Stephen; /Fermilab; Kim, Young-Kee; /Fermilab /Chicago U.; Lankford, Andrew; /UC, Irvine; McGinnis, David; /Fermilab; Nagaitsev, Sergei; /Fermilab; Raubenheimer, Tor; /SLAC /Fermilab

    2007-01-01

    The Fermilab Steering Group has developed a plan to keep U.S. accelerator-based particle physics on the pathway to discovery, both at the Terascale with the LHC and the ILC and in the domain of neutrinos and precision physics with a high-intensity accelerator. The plan puts discovering Terascale physics with the LHC and the ILC as Fermilab's highest priority. While supporting ILC development, the plan creates opportunities for exciting science at the intensity frontier. If the ILC remains near the Global Design Effort's technically driven timeline, Fermilab would continue neutrino science with the NOVA experiment, using the NuMI (Neutrinos at the Main Injector) proton plan, scheduled to begin operating in 2011. If ILC construction must wait somewhat longer, Fermilab's plan proposes SNuMI, an upgrade of NuMI to create a more powerful neutrino beam. If the ILC start is postponed significantly, a central feature of the proposed Fermilab plan calls for building an intense proton facility, Project X, consisting of a linear accelerator with the currently planned characteristics of the ILC combined with Fermilab's existing Recycler Ring and the Main Injector accelerator. The major component of Project X is the linac. Cryomodules, radio-frequency distribution, cryogenics and instrumentation for the linac are the same as or similar to those used in the ILC at a scale of about one percent of a full ILC linac. Project X's intense proton beams would open a path to discovery in neutrino science and in precision physics with charged leptons and quarks. World-leading experiments would allow physicists to address key questions of the Quantum Universe: How did the universe come to be? Are there undiscovered principles of nature: new symmetries, new physical laws? Do all the particles and forces become one? What happened to the antimatter? Building Project X's ILC-like linac would offer substantial support for ILC development by accelerating the

  2. Linear deformations of discrete groups and constructions of multivalued groups

    International Nuclear Information System (INIS)

    Yagodovskii, Petr V

    2000-01-01

    We construct deformations of discrete multivalued groups described as special deformations of their group algebras in the class of finite-dimensional associative algebras. We show that the deformations of ordinary groups producing multivalued groups are defined by cocycles with coefficients in the group algebra of the original group and obtain classification theorems on these deformations. We indicate a connection between the linear deformations of discrete groups introduced in this paper and the well-known constructions of multivalued groups. We describe the manifold of three-dimensional associative commutative algebras with identity element, fixed basis, and a constant number of values. The group algebras of n-valued groups of order three (three-dimensional n-group algebras) form a discrete set in this manifold

  3. Group B Streptococcus and Pregnancy

    Science.gov (United States)

    ... B Strep and Pregnancy • What is group B streptococcus (GBS)? • What does it mean to be colonized ... planned cesarean birth? •Glossary What is group B streptococcus (GBS)? Group B streptococcus is one of the ...

  4. Harmonic Analysis and Group Representation

    CERN Document Server

    Figa-Talamanca, Alessandro

    2011-01-01

    This title includes: Lectures - A. Auslander, R. Tolimeri - Nilpotent groups and abelian varieties, M Cowling - Unitary and uniformly bounded representations of some simple Lie groups, M. Duflo - Construction de representations unitaires d'un groupe de Lie, R. Howe - On a notion of rank for unitary representations of the classical groups, V.S. Varadarajan - Eigenfunction expansions of semisimple Lie groups, and R. Zimmer - Ergodic theory, group representations and rigidity; and, Seminars - A. Koranyi - Some applications of Gelfand pairs in classical analysis.

  5. Topological K-Kolmogorov groups

    International Nuclear Information System (INIS)

    Abd El-Sattar, A. Dabbour.

    1987-07-01

    The idea of the K-groups was used to define K-Kolmogorov homology and cohomology (over pairs of coefficient groups) which are descriptions of certain modifications of the Kolmogorov groups. The present work is devoted to the study of the topological properties of the K-Kolmogorov groups which lie at the root of the group duality based essentially upon Pontrjagin's concept of group multiplication. 14 refs

  6. Post-Disaster Social Justice Group Work and Group Supervision

    Science.gov (United States)

    Bemak, Fred; Chung, Rita Chi-Ying

    2011-01-01

    This article discusses post-disaster group counseling and group supervision using a social justice orientation for working with post-disaster survivors from underserved populations. The Disaster Cross-Cultural Counseling model is a culturally responsive group counseling model that infuses social justice into post-disaster group counseling and…

  7. Group Leader Development: Effects of Personal Growth and Psychoeducational Groups

    Science.gov (United States)

    Ohrt, Jonathan H.; Robinson, E. H., III; Hagedorn, W. Bryce

    2013-01-01

    The purpose of this quasi-experimental study was to compare the effects of personal growth groups and psychoeducational groups on counselor education students' (n = 74) empathy and group leader self-efficacy. Additionally, we compared the degree to which participants in each group valued: (a) cohesion, (b) catharsis, and (c) insight. There were no…

  8. Feminist Principles in Survivor's Groups: Out-of-Group Contact.

    Science.gov (United States)

    Rittenhouse, JoAn

    1997-01-01

    Illustrates the value of theoretical concepts from Feminist Therapy in the group treatment of women survivors. Theoretical underpinnings are supported using data taken from clinical experience and by examining group themes and out-of-group contact developed from the case sample. Principles regarding feminist groups are proposed. (RJM)

  9. Platinum-group elements

    Science.gov (United States)

    Zientek, Michael L.; Loferski, Patricia J.; Parks, Heather L.; Schulte, Ruth F.; Seal, Robert R.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The platinum-group elements (PGEs)—platinum, palladium, rhodium, ruthenium, iridium, and osmium—are metals that have similar physical and chemical properties and tend to occur together in nature. PGEs are indispensable to many industrial applications but are mined in only a few places. The availability and accessibility of PGEs could be disrupted by economic, environmental, political, and social events. The United States net import reliance as a percentage of apparent consumption is about 90 percent.PGEs have many industrial applications. They are used in catalytic converters to reduce carbon monoxide, hydrocarbon, and nitrous oxide emissions in automobile exhaust. The chemical industry requires platinum or platinum-rhodium alloys to manufacture nitric oxide, which is the raw material used to manufacture explosives, fertilizers, and nitric acid. In the petrochemical industry, platinum-supported catalysts are needed to refine crude oil and to produce aromatic compounds and high-octane gasoline. Alloys of PGEs are exceptionally hard and durable, making them the best known coating for industrial crucibles used in the manufacture of chemicals and synthetic materials. PGEs are used by the glass manufacturing industry in the production of fiberglass and flat-panel and liquid crystal displays. In the electronics industry, PGEs are used in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors.Aside from their industrial applications, PGEs are used in such other fields as health, consumer goods, and finance. Platinum, for example, is used in medical implants, such as pacemakers, and PGEs are used in cancer-fighting drugs. Platinum alloys are an ideal choice for jewelry because of their white color, strength, and resistance to tarnish. Platinum, palladium, and rhodium in the form of coins and bars are also used as investment commodities, and various financial instruments based on the value of these PGEs are traded on major exchanges

  10. Emotional collectives: How groups shape emotions and emotions shape groups.

    Science.gov (United States)

    van Kleef, Gerben A; Fischer, Agneta H

    2016-01-01

    Group settings are epicentres of emotional activity. Yet, the role of emotions in groups is poorly understood. How do group-level phenomena shape group members' emotional experience and expression? How are emotional expressions recognised, interpreted and shared in group settings? And how do such expressions influence the emotions, cognitions and behaviours of fellow group members and outside observers? To answer these and other questions, we draw on relevant theoretical perspectives (e.g., intergroup emotions theory, social appraisal theory and emotions as social information theory) and recent empirical findings regarding the role of emotions in groups. We organise our review according to two overarching themes: how groups shape emotions and how emotions shape groups. We show how novel empirical approaches break important new ground in uncovering the role of emotions in groups. Research on emotional collectives is thriving and constitutes a key to understanding the social nature of emotions.

  11. Group performance and group learning at dynamic system control tasks

    International Nuclear Information System (INIS)

    Drewes, Sylvana

    2013-01-01

    Proper management of dynamic systems (e.g. cooling systems of nuclear power plants or production and warehousing) is important to ensure public safety and economic success. So far, research has provided broad evidence for systematic shortcomings in individuals' control performance of dynamic systems. This research aims to investigate whether groups manifest synergy (Larson, 2010) and outperform individuals and if so, what processes lead to these performance advantages. In three experiments - including simulations of a nuclear power plant and a business setting - I compare the control performance of three-person-groups to the average individual performance and to nominal groups (N = 105 groups per experiment). The nominal group condition captures the statistical advantage of aggregated group judgements not due to social interaction. First, results show a superior performance of groups compared to individuals. Second, a meta-analysis across all three experiments shows interaction-based process gains in dynamic control tasks: Interacting groups outperform the average individual performance as well as the nominal group performance. Third, group interaction leads to stable individual improvements of group members that exceed practice effects. In sum, these results provide the first unequivocal evidence for interaction-based performance gains of groups in dynamic control tasks and imply that employers should rely on groups to provide opportunities for individual learning and to foster dynamic system control at its best.

  12. Does group efficacy increase group identification? Resolving their paradoxical relationship

    NARCIS (Netherlands)

    van Zomeren, Martijn; Leach, Colin Wayne; Spears, Russell

    2010-01-01

    Although group identification and group efficacy are both important predictors of collective action against collective disadvantage, there is mixed evidence for their (causal) relationship. Meta-analytic and correlational evidence suggests an overall positive relationship that has been interpreted

  13. Secure Group Communications for Large Dynamic Multicast Group

    Institute of Scientific and Technical Information of China (English)

    Liu Jing; Zhou Mingtian

    2003-01-01

    As the major problem in multicast security, the group key management has been the focus of research But few results are satisfactory. In this paper, the problems of group key management and access control for large dynamic multicast group have been researched and a solution based on SubGroup Secure Controllers (SGSCs) is presented, which solves many problems in IOLUS system and WGL scheme.

  14. How to conduct focus groups: researching group priorities through discussion.

    Science.gov (United States)

    1992-01-01

    Focus groups serve to uncover priorities and beliefs of a target group, but health project designers do not always take the time to seek this information beforehand. Focus groups also allow various local subgroups to communicate their concerns before the project starts. Focus groups can also breed ideas and dialogue that individual interviews cannot and they provide baseline information so managers can determine if attitudes or priorities have resulted from the project. Diverse people have different beliefs, e.g., women who have young children view oral rehydration therapy differently from women with no children. Project designers can use these basic differences to arrive at some conclusions about general attitudes. Focus group facilitators should have a discussion outline to help keep the group on the topic of concern. They should limit sessions to 60-90 minutes. Each focus groups should include 8-10 people. It is important to have members of various community subgroups in each group. Yet group designers should be careful not to include within the same group, those who may intimidate other people in the group, e.g., in situations where farmers depend on middlemen, farmers may not be open if middlemen are also in the focus group. Facilitators should launch each session with an attempt to encourage the members to be open and to feel comfortable. For example, in Malawi, a facilitator leads her focus group discussions with songs. Stories are another icebreaker. It is important that all focus groups centering around a certain project discuss the same topics. Facilitators need to stress to the group that all discussions are to be kept confidential. The designers should also carefully word the questions so that facilitators will not impart their bias. Facilitators should not direct the group to certain conclusions, but instead keep the discussions focused.

  15. Group covariance and metrical theory

    International Nuclear Information System (INIS)

    Halpern, L.

    1983-01-01

    The a priori introduction of a Lie group of transformations into a physical theory has often proved to be useful; it usually serves to describe special simplified conditions before a general theory can be worked out. Newton's assumptions of absolute space and time are examples where the Euclidian group and translation group have been introduced. These groups were extended to the Galilei group and modified in the special theory of relativity to the Poincare group to describe physics under the given conditions covariantly in the simplest way. The criticism of the a priori character leads to the formulation of the general theory of relativity. The general metric theory does not really give preference to a particular invariance group - even the principle of equivalence can be adapted to a whole family of groups. The physical laws covariantly inserted into the metric space are however adapted to the Poincare group. 8 references

  16. Defining and Classifying Interest Groups

    DEFF Research Database (Denmark)

    Baroni, Laura; Carroll, Brendan; Chalmers, Adam

    2014-01-01

    The interest group concept is defined in many different ways in the existing literature and a range of different classification schemes are employed. This complicates comparisons between different studies and their findings. One of the important tasks faced by interest group scholars engaged...... in large-N studies is therefore to define the concept of an interest group and to determine which classification scheme to use for different group types. After reviewing the existing literature, this article sets out to compare different approaches to defining and classifying interest groups with a sample...... in the organizational attributes of specific interest group types. As expected, our comparison of coding schemes reveals a closer link between group attributes and group type in narrower classification schemes based on group organizational characteristics than those based on a behavioral definition of lobbying....

  17. What Is a Group? Young Children's Perceptions of Different Types of Groups and Group Entitativity.

    Directory of Open Access Journals (Sweden)

    Maria Plötner

    Full Text Available To date, developmental research on groups has focused mainly on in-group biases and intergroup relations. However, little is known about children's general understanding of social groups and their perceptions of different forms of group. In this study, 5- to 6-year-old children were asked to evaluate prototypes of four key types of groups: an intimacy group (friends, a task group (people who are collaborating, a social category (people who look alike, and a loose association (people who coincidently meet at a tram stop. In line with previous work with adults, the vast majority of children perceived the intimacy group, task group, and social category, but not the loose association, to possess entitativity, that is, to be a 'real group.' In addition, children evaluated group member properties, social relations, and social obligations differently in each type of group, demonstrating that young children are able to distinguish between different types of in-group relations. The origins of the general group typology used by adults thus appear early in development. These findings contribute to our knowledge about children's intuitive understanding of groups and group members' behavior.

  18. Effectiveness of Group Supervision versus Combined Group and Individual Supervision.

    Science.gov (United States)

    Ray, Dee; Altekruse, Michael

    2000-01-01

    Investigates the effectiveness of different types of supervision (large group, small group, combined group, individual supervision) with counseling students (N=64). Analyses revealed that all supervision formats resulted in similar progress in counselor effectiveness and counselor development. Participants voiced a preference for individual…

  19. Group Insight Versus Group Desensitization in Treating Speech Anxiety

    Science.gov (United States)

    Meichenbaum, Donald H.; And Others

    1971-01-01

    Results of this study indicated that the insight group was as effective as the desensitization group in significantly reducing speech anxiety over control group levels as assessed by behavioral, cognitive, and self-report measures given immediately after posttreatment and later at a three-month follow-up. (Author)

  20. Re-Examining Group Development in Adventure Therapy Groups.

    Science.gov (United States)

    DeGraaf, Don; Ashby, Jeff

    1998-01-01

    Small-group development is an important aspect of adventure therapy. Supplementing knowledge of sequential stages of group development with knowledge concerning within-stage nonsequential development yields a richer understanding of groups. Integrating elements of the individual counseling relationship (working alliance, transference, and real…

  1. Saving Face and Group Identity

    DEFF Research Database (Denmark)

    Eriksson, Tor; Mao, Lei; Villeval, Marie-Claire

    2015-01-01

    their self- but also other group members' image. This behavior is frequent even in the absence of group identity. When group identity is more salient, individuals help regardless of whether the least performer is an in-group or an out-group. This suggests that saving others' face is a strong social norm.......Are people willing to sacrifice resources to save one's and others' face? In a laboratory experiment, we study whether individuals forego resources to avoid the public exposure of the least performer in their group. We show that a majority of individuals are willing to pay to preserve not only...

  2. Enhancing Social Communication Between Groups

    NARCIS (Netherlands)

    T. Stevens; P. Hughes (Peter); D. Williams; I. Craigie; I. Kegel; P.S. Cesar Garcia (Pablo Santiago); A.J. Jansen (Jack); M.F. Usrsu; M. Frantzis; N. Farber; M. Lutzky; S. Vogel

    2010-01-01

    htmlabstractThis paper describes a prototype software platform that supports advanced communications services, specifically services enabling effective group-to-group communications with a social purpose, between remote homes. The architecture, the individual components, their interfaces, and the

  3. Coordinated Control of Vehicle Groups

    National Research Council Canada - National Science Library

    Kumar, Vijay

    2004-01-01

    .... There are three main objectives: (1) to develop a theoretical paradigm for formalizing the concepts of a group, a team, and control of groups, with specified tasks such as exploring, mapping, searching, and transporting objects; (2...

  4. Criminal groups and criminal subculture

    OpenAIRE

    Romanova N.M.

    2013-01-01

    The paper provides a classification of criminal groups, structured by the following parameters: a) operation mode (secret/open), b) law-enforcement and administrative support (presence/absence). We describe four types of criminal groups: a) legitimized criminal organization, b) secret criminal organization engaged in illegal business, c) secret general crime group, and d) general crime group operating openly. The four types differ in the content of criminal subculture. Modern criminal subcult...

  5. Group Cooperation in Outdoor Education

    Science.gov (United States)

    Matthews, Bruce E.

    1978-01-01

    Utilizing the Beatles' Yellow Submarine fantasy (e.g., the Blue Meanies), this outdoor education program is designed for sixth graders and special education students. Activities developed at the Cortland Resident Outdoor Education Camp include a series of group stress/challenge activities to be accomplished by everyone in the group, as a group.…

  6. Reinterpreting between-group inequality

    NARCIS (Netherlands)

    Elbers, C.T.M.; Lanjouw, P.F.; Mistiaen, J.; Özler, B

    2008-01-01

    We evaluate observed inequality between population groups against a benchmark of the maximum between-group inequality attainable given the number and relative sizes of those groups under examination. Because our measure is normalized by these parameters, drawing comparisons across different settings

  7. Ability Grouping in Social Studies.

    Science.gov (United States)

    Social Education, 1992

    1992-01-01

    Presents a position statement of the National Council for the Social Studies (NCSS). Reports that the NCSS objects to ability grouping in social studies. Argues that ability grouping disadvantages minority, handicapped, and low ability students. Suggests that ability grouping undermines the democratic ideals that should be the basis of the social…

  8. Conceptualizing Group Flow: A Framework

    Science.gov (United States)

    Duncan, Jana; West, Richard E.

    2018-01-01

    This literature review discusses the similarities in main themes between Csikszentmihályi theory of individual flow and Sawyer theory of group flow, and compares Sawyer's theory with existing concepts in the literature on group work both in education and business. Because much creativity and innovation occurs within groups, understanding group…

  9. Diagram Techniques in Group Theory

    Science.gov (United States)

    Stedman, Geoffrey E.

    2009-09-01

    Preface; 1. Elementary examples; 2. Angular momentum coupling diagram techniques; 3. Extension to compact simple phase groups; 4. Symmetric and unitary groups; 5. Lie groups and Lie algebras; 6. Polarisation dependence of multiphoton processes; 7. Quantum field theoretic diagram techniques for atomic systems; 8. Applications; Appendix; References; Indexes.

  10. Designing for informed group formation

    DEFF Research Database (Denmark)

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive...

  11. Working with Difficult Group Members.

    Science.gov (United States)

    Kottler, Jeffrey A.

    1994-01-01

    Describes types of group members who are challenging in group settings including entitled, manipulative, and character-disordered clients. Provides suggestions for working with these group members, either as isolated cases or as homogenous populations, emphasizing the protection of other clients' rights. Includes 31 references. (Author/CRR)

  12. K-Kolmogorov cohomology groups

    International Nuclear Information System (INIS)

    Abd El-Sattar, A. Dabbour.

    1986-07-01

    In the present work we use the idea of K-groups to give a description of certain modification of the Kolmogorov cohomology groups for the case of a pair (G,G') of discrete coefficient groups. Their induced homomorphisms and coboundary operators are also defined, and then we study the resulting construction from the point of view of Eilenberg-Steenrod axioms. (author)

  13. Ultrafilters and topologies on groups

    CERN Document Server

    Zelenyuk, Yevhen

    2011-01-01

    This book presents the relationship between ultrafilters and topologies on groups. It shows how ultrafilters are used in constructing topologies on groups with extremal properties and how topologies on groups serve in deriving algebraic results aboutultrafilters. Topics covered include: topological and left topological groups, ultrafilter semigroups, local homomorphisms and automorphisms, subgroups and ideal structure of ßG, almost maximal spaces and projectives of finite semigroups, resolvability of groups. This is a self-contained book aimed at graduate students and researchers working in to

  14. Group supervision for general practitioners

    DEFF Research Database (Denmark)

    Galina Nielsen, Helena; Sofie Davidsen, Annette; Dalsted, Rikke

    2013-01-01

    AIM: Group supervision is a sparsely researched method for professional development in general practice. The aim of this study was to explore general practitioners' (GPs') experiences of the benefits of group supervision for improving the treatment of mental disorders. METHODS: One long-establish......AIM: Group supervision is a sparsely researched method for professional development in general practice. The aim of this study was to explore general practitioners' (GPs') experiences of the benefits of group supervision for improving the treatment of mental disorders. METHODS: One long...... considered important prerequisites for disclosing and discussing professional problems. CONCLUSION: The results of this study indicate that participation in a supervision group can be beneficial for maintaining and developing GPs' skills in dealing with patients with mental health problems. Group supervision...... influenced other areas of GPs' professional lives as well. However, more studies are needed to assess the impact of supervision groups....

  15. Group percolation in interdependent networks

    Science.gov (United States)

    Wang, Zexun; Zhou, Dong; Hu, Yanqing

    2018-03-01

    In many real network systems, nodes usually cooperate with each other and form groups to enhance their robustness to risks. This motivates us to study an alternative type of percolation, group percolation, in interdependent networks under attack. In this model, nodes belonging to the same group survive or fail together. We develop a theoretical framework for this group percolation and find that the formation of groups can improve the resilience of interdependent networks significantly. However, the percolation transition is always of first order, regardless of the distribution of group sizes. As an application, we map the interdependent networks with intersimilarity structures, which have attracted much attention recently, onto the group percolation and confirm the nonexistence of continuous phase transitions.

  16. The "group" in obstetric psychoprophylaxis.

    Science.gov (United States)

    Volpe, B; Tenaglia, F; Fede, T; Cerutti, R

    1983-01-01

    In the practice of obstetric psychoprophylaxis every method employed considered always the group both from a psychological and a pedagogic point of view. Today the group of pregnant women (or couples) is considered under various aspects: - psychological: the group as a support for members with regard to maternal and parental emotional feelings; - anthropological: the group fills up an empty vital space and becomes a "rite de passage" from a state of social identity to another one; - social: the group is a significative cultural intermediary between health services and the women-patient. The knowledge of these aspects becomes an important methodological support for group conductors. We present an analysis of our experience with groups and how this has affected the Psychoprophylaxis in the last years.

  17. Group lending and the role of the group leader

    OpenAIRE

    Eijkel, van, R.; Hermes, N.; Lensink, B.W.

    2011-01-01

    This paper investigates strategic monitoring behavior within group lending. We show that monitoring efforts of group members differ in equilibrium due to the asymmetry between members in terms of future profits. In particular, we show that the entrepreneur with the highest future profits also puts in the highest monitoring effort. Moreover, monitoring efforts differ between group members due to free-riding: one member reduces her level of monitoring if the other increases her monitoring effor...

  18. Clifford algebras, spinors, spin groups and covering groups

    International Nuclear Information System (INIS)

    Magneville, C.; Pansart, J.P.

    1991-03-01

    The Dirac equation uses matrices named Υ matrices which are representations of general algebraic structures associated with a metric space. These algebras are the Clifford algebras. In the first past, these algebras are studied. Then the notion of spinor is developed. It is shown that Majorana and Weyl spinors only exist for some particular metric space. In the second part, Clifford and spinor groups are studied. They may be interpreted as the extension of the notion of orthogonal group for Clifford algebras and their spaces for representation. The rotation of a spinor is computed. In the last part, the connexion between the spinor groups and the Universal Covering Groups is presented [fr

  19. Group lending and the role of the group leader

    NARCIS (Netherlands)

    Eijkel, van R.; Hermes, N.; Lensink, B.W.

    2011-01-01

    This paper investigates strategic monitoring behavior within group lending. We show that monitoring efforts of group members differ in equilibrium due to the asymmetry between members in terms of future profits. In particular, we show that the entrepreneur with the highest future profits also puts

  20. Group lending and the role of the group leader

    NARCIS (Netherlands)

    van Eijkel, R.; Hermes, C.L.M.; Lensink, B.W.

    This paper investigates strategic monitoring behavior within group lending. We show that monitoring efforts of group members differ in equilibrium due to the asymmetry between members in terms of future profits. In particular, we show that the entrepreneur with the highest future profits also puts

  1. Working with Group-Tasks and Group Cohesiveness

    Science.gov (United States)

    Anwar, Khoirul

    2016-01-01

    This study aimed at exploring the connection between the use of group task and group cohesiveness. This study is very important because the nature of the learner's success is largely determined by the values of cooperation, interaction, and understanding of the learning objectives together. Subjects of this study are 28 students on the course…

  2. Group Journaling: A Tool for Reflection, Fun and Group Development

    Science.gov (United States)

    Asfeldt, Morten

    2012-01-01

    Personal journaling is common practice in outdoor programs and is an important means of reflection and meaning-making. For over 20 years the author has used group journals to promote reflection and understanding, raise important questions, explore difficult issues, develop writing and speaking skills, and enhance group development. In this…

  3. Group Milieu in systemic and psychodynamic group therapy

    DEFF Research Database (Denmark)

    Lau, Marianne Engelbrecht; Kristensen, Ellids

    Objectives: A recent meta-analysis also concluded that psychotherapeutic approaches are beneficial for adult with a history of CSA and maintained for at least six months follow-up. The results suggest that different characteristics of therapy moderate the therapeutic outcome. We found in a random......Objectives: A recent meta-analysis also concluded that psychotherapeutic approaches are beneficial for adult with a history of CSA and maintained for at least six months follow-up. The results suggest that different characteristics of therapy moderate the therapeutic outcome. We found...... in a randomized study of systemic versus psychodynamic group therapy, that the short-term outcome for patients who received systemic group psychotherapy was significantly better than the outcome for patients who received psychodynamic group psychotherapy. The current study assessed the group milieu in both groups....... Methods: This randomized prospective study included 106 women: 52 assigned to psychodynamic group psychotherapy and 54 assigned to systemic group psychotherapy. The Group Environment Scale (GES) was filled in the mid phase of therapy and analysed in three dimensions and 10 subscales. Results: The systemic...

  4. Geometric group theory an introduction

    CERN Document Server

    Löh, Clara

    2017-01-01

    Inspired by classical geometry, geometric group theory has in turn provided a variety of applications to geometry, topology, group theory, number theory and graph theory. This carefully written textbook provides a rigorous introduction to this rapidly evolving field whose methods have proven to be powerful tools in neighbouring fields such as geometric topology. Geometric group theory is the study of finitely generated groups via the geometry of their associated Cayley graphs. It turns out that the essence of the geometry of such groups is captured in the key notion of quasi-isometry, a large-scale version of isometry whose invariants include growth types, curvature conditions, boundary constructions, and amenability. This book covers the foundations of quasi-geometry of groups at an advanced undergraduate level. The subject is illustrated by many elementary examples, outlooks on applications, as well as an extensive collection of exercises.

  5. Group Analytic Psychotherapy in Brazil.

    Science.gov (United States)

    Penna, Carla; Castanho, Pablo

    2015-10-01

    Group analytic practice in Brazil began quite early. Highly influenced by the Argentinean Pichon-Rivière, it enjoyed a major development from the 1950s to the early 1980s. Beginning in the 1970s, different factors undermined its development and eventually led to its steep decline. From the mid 1980s on, the number of people looking for either group analytic psychotherapy or group analytic training decreased considerably. Group analytic psychotherapy societies struggled to survive and most of them had to close their doors in the 1990s and the following decade. Psychiatric reform and the new public health system have stimulated a new demand for groups in Brazil. Developments in the public and not-for-profit sectors, combined with theoretical and practical research in universities, present promising new perspectives for group analytic psychotherapy in Brazil nowadays.

  6. Modelling group dynamic animal movement

    DEFF Research Database (Denmark)

    Langrock, Roland; Hopcraft, J. Grant C.; Blackwell, Paul G.

    2014-01-01

    makes its movement decisions relative to the group centroid. The basic idea is framed within the flexible class of hidden Markov models, extending previous work on modelling animal movement by means of multi-state random walks. While in simulation experiments parameter estimators exhibit some bias......, to date, practical statistical methods which can include group dynamics in animal movement models have been lacking. We consider a flexible modelling framework that distinguishes a group-level model, describing the movement of the group's centre, and an individual-level model, such that each individual......Group dynamic movement is a fundamental aspect of many species' movements. The need to adequately model individuals' interactions with other group members has been recognised, particularly in order to differentiate the role of social forces in individual movement from environmental factors. However...

  7. Discrepancy in abo blood grouping

    International Nuclear Information System (INIS)

    Khan, M.N.; Ahmed, Z.; Khan, T.A.

    2013-01-01

    Discrepancies in blood typing is one of the major reasons in eliciting a transfusion reaction. These discrepancies can be avoided through detailed analysis for the blood typing. Here, we report a subgroup of blood group type-B in the ABO system. Donor's blood was analyzed by employing commercial antisera for blood grouping. The results of forward (known antisera) and reverse (known antigen) reaction were not complimentary. A detailed analysis using the standard protocols by American Association of Blood Banking revealed the blood type as a variant of blood group-B instead of blood group-O. This is suggestive of the fact that blood group typing should be performed with extreme care and any divergence, if identified, should be properly resolved to avoid transfusion reactions. Moreover, a major study to determine the blood group variants in Pakistani population is needed. (author)

  8. The didactics of group work

    DEFF Research Database (Denmark)

    Christensen, Gerd

    2017-01-01

    The aim of this paper is to discuss aims and means of group work as a teaching and learning method. In Denmark, group work has been implemented at all levels of education since the 1970s from primary school to university but also in training sessions in organizations. The discussion in this paper...... will take its point of departure in pedagogical textbook introductions where group work is often presented as a means to learning social skills and co-workability. However, as most students and teachers know, this is not always the case. Observations of long-term group work show that this can be a tough...... experience for the students (Christensen 2013). Contrary to expectations, the group work seemed to foster anti-social behavior and development of selfish skills. The paper will therefore conclude by suggesting how the (often) laissez-faire group pedagogy, which is dominant in Denmark, could be improved...

  9. Uniquely Strongly Clean Group Rings

    Institute of Scientific and Technical Information of China (English)

    WANG XIU-LAN

    2012-01-01

    A ring R is called clean if every element is the sum of an idempotent and a unit,and R is called uniquely strongly clean (USC for short) if every element is uniquely the sum of an idempotent and a unit that commute.In this article,some conditions on a ring R and a group G such that RG is clean are given.It is also shown that if G is a locally finite group,then the group ring RG is USC if and only if R is USC,and G is a 2-group.The left uniquely exchange group ring,as a middle ring of the uniquely clean ring and the USC ring,does not possess this property,and so does the uniquely exchange group ring.

  10. Group theory and its applications

    CERN Document Server

    Patra, Prasanta Kumar

    2018-01-01

    Every molecule possesses symmetry and hence has symmetry operations and symmetry elements. From symmetry properties of a system we can deduce its significant physical results. Consequently it is essential to operations of a system forms a group. Group theory is an abstract mathematical tool that underlies the study of symmetry and invariance. By using the concepts of symmetry and group theory, it is possible to obtain the members of complete set of known basis functions of the various irreducible representations of the group. I practice this is achieved by applying the projection operators to linear combinations of atomic orbital (LCAO) when the valence electrons are tightly bound to the ions, to orthogonalized plane waves (OPW) when valence electrons are nearly free and to the other given functions that are judged to the particular system under consideration. In solid state physics the group theory is indispensable in the context of finding the energy bands of electrons in solids. Group theory can be applied...

  11. Physics of the Lorentz Group

    Science.gov (United States)

    Başkal, Sibel

    2015-11-01

    This book explains the Lorentz mathematical group in a language familiar to physicists. While the three-dimensional rotation group is one of the standard mathematical tools in physics, the Lorentz group of the four-dimensional Minkowski space is still very strange to most present-day physicists. It plays an essential role in understanding particles moving at close to light speed and is becoming the essential language for quantum optics, classical optics, and information science. The book is based on papers and books published by the authors on the representations of the Lorentz group based on harmonic oscillators and their applications to high-energy physics and to Wigner functions applicable to quantum optics. It also covers the two-by-two representations of the Lorentz group applicable to ray optics, including cavity, multilayer and lens optics, as well as representations of the Lorentz group applicable to Stokes parameters and the Poincaré sphere on polarization optics.

  12. Groups, graphs and random walks

    CERN Document Server

    Salvatori, Maura; Sava-Huss, Ecaterina

    2017-01-01

    An accessible and panoramic account of the theory of random walks on groups and graphs, stressing the strong connections of the theory with other branches of mathematics, including geometric and combinatorial group theory, potential analysis, and theoretical computer science. This volume brings together original surveys and research-expository papers from renowned and leading experts, many of whom spoke at the workshop 'Groups, Graphs and Random Walks' celebrating the sixtieth birthday of Wolfgang Woess in Cortona, Italy. Topics include: growth and amenability of groups; Schrödinger operators and symbolic dynamics; ergodic theorems; Thompson's group F; Poisson boundaries; probability theory on buildings and groups of Lie type; structure trees for edge cuts in networks; and mathematical crystallography. In what is currently a fast-growing area of mathematics, this book provides an up-to-date and valuable reference for both researchers and graduate students, from which future research activities will undoubted...

  13. Group identity and positive deviance in work groups.

    Science.gov (United States)

    Kim, Moon Joung; Choi, Jin Nam

    2017-12-05

    This study examines why and how identity cognitions, including group identification and individual differentiation, influence the positive deviance of employees. We identify the risk-taking intention of employees as a critical psychological mechanism to overcome stigma-induced identity threat of positive deviance. The analysis of data collected from 293 members comprising 66 work teams reveals that the relationship between individual differentiation and positive deviance is partially mediated by risk-taking intention. The indirect effect of group identification on positive deviance through risk-taking intention is also significant and positive in groups with low conformity pressure, whereas the same indirect effect is neutralized in groups with high conformity pressure. The current analysis offers new insights into the way the group context and the identity cognition of members explain the development of positive deviance and workplace creativity.

  14. Social Identity and Group Contests

    OpenAIRE

    Zaunbrecher, Henrik; Riedl, Arno

    2016-01-01

    Social identity has been shown to successfully enhance cooperation and effort in cooperation and coordination games. Little is known about the causal effect of social identity on the propensity to engage in group conflict. In this paper we explore theoretically and experimentally whether social identity increases investments in group contests. We show theoretically that increased social identity with the own group implies higher investments in Tullock contests. Empirically we find that induce...

  15. Designing for informed group formation

    DEFF Research Database (Denmark)

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive....... Following research based design methodology an experiment separating the two was initiated.This was to provide for more openness and creativity in contrast to a design in which existing relations seem predominant....

  16. Group decision-making: Factors that affect group effectiveness

    Directory of Open Access Journals (Sweden)

    Juliana Osmani

    2016-03-01

    Full Text Available Organizations are operating in a dynamic and turbulent environment. In these conditions, they have to make decisions for new problems or situations. Most of decisions are therefore non-programmed and unstructured, accompanied by risk and uncertainty. Moreover, the problems and situations are complex. All organizations are oriented towards group decisionmaking processes, as useful tools to cope with uncertainty and complexity. Apart from the necessity, companies are turning towards participatory processes also to benefit from the important advantages that these processes offer. Organizations have realized the importance of group decision-making processes to contribute to the creation of sustainable competitive advantages. Main objective of this paper is to show that group decision-making processes do not offer guarantee for good decisions, because the effectiveness of group is affected by many factors. So, the first thing done in this paper is discussing about the benefits and limitations that accompany the use of groups with decision-making purpose. Afterwards, we stop on the different factors that influence the group’s ability to make good decisions. The aim is to emphasize that regardless of the many advantages of groups, some factors as group size, type of communication within the group, leadership style, the norms, the differentiation of roles and statuses, cohesion and compliance degree should be the main elements to keep into consideration because they affect the effectiveness of group. In this regard, is discussed how such factors influence the quality of decision and then we try to draw some conclusions that can improve and make better and easier group decision-making processes.

  17. Strategic Groups and Banks’ Performance

    Directory of Open Access Journals (Sweden)

    Gregorz Halaj

    2009-06-01

    Full Text Available The theory of strategic groups predicts the existence of stable groups of companies that adopt similar business strategies. The theory also predicts that groups will differ in performance and in their reaction to external shocks. We use cluster analysis to identify strategic groups in the Polish banking sector. We find stable groups in the Polish banking sector constituted after the year 2000 following the major privatisation and ownership changes connected with transition to the mostly-privately-owned banking sector in the late 90s. Using panel regression methods we show that the allocation of banks to groups is statistically significant in explaining the profitability of banks. Thus, breaking down the banks into strategic groups and allowing for the different reaction of the groups to external shocks helps in a more accurate explanation of profits of the banking sector as a whole.Therefore, a more precise ex ante assessment of the loss absorption capabilities of banks is possible, which is crucial for an analysis of banking sector stability. However, we did not find evidence of the usefulness of strategic groups in explaining the quality of bank portfolios as measured by irregular loans over total loans, which is a more direct way to assess risks to financial stability.

  18. Structure of a supergravity group

    International Nuclear Information System (INIS)

    Ogievetsky, V.; Sokatchev, E.

    1978-01-01

    The supergravity group is found to be the direct product of general covariance groups in complex conjugated left and right handed superspaces. The ordinary space-time coordinate and the axial gravitational superfield are the real and imaginary parts of the complex coordinate, respectively. It is pointed out that a number of questions concerning the formalism remains open. For instance how to define superfields with external indices, supercovariant derivatives and invariants of the group, etc. However, the extremely simple and clear geometrical picture of the supergravity group given here will provide an adequate basis for the supergravity theory

  19. The formalism of Lie groups

    Energy Technology Data Exchange (ETDEWEB)

    Salam, A. [Imperial College of Science and Technology, London (United Kingdom)

    1963-01-15

    Throughout the history of quantum theory, a battle has raged between the amateurs and professional group theorists. The amateurs have maintained that everything one needs in the theory of groups can be discovered by the light of nature provided one knows how to multiply two matrices. In support of this claim, they of course, justifiably, point to the successes of that prince of amateurs in this field, Dirac, particularly with the spinor representations of the Lorentz group. As an amateur myself, I strongly believe in the truth of the non-professionalist creed. I think perhaps there is not much one has to learn in the way of methodology from the group theorists except caution. But this does not mean one should not be aware of the riches which have been amassed over the course of years particularly in that most highly developed of all mathematical disciplines - the theory of Lie groups. My lectures then are an amateur's attempt to gather some of the fascinating results for compact simple Lie groups which are likely to be of physical interest. I shall state theorems; and with a physicist's typical unconcern rarely, if ever, shall I prove these. Throughout, the emphasis will be to show the close similarity of these general groups with that most familiar of all groups, the group of rotations in three dimensions.

  20. Leadership in moving human groups.

    Directory of Open Access Journals (Sweden)

    Margarete Boos

    2014-04-01

    Full Text Available How is movement of individuals coordinated as a group? This is a fundamental question of social behaviour, encompassing phenomena such as bird flocking, fish schooling, and the innumerable activities in human groups that require people to synchronise their actions. We have developed an experimental paradigm, the HoneyComb computer-based multi-client game, to empirically investigate human movement coordination and leadership. Using economic games as a model, we set monetary incentives to motivate players on a virtual playfield to reach goals via players' movements. We asked whether (I humans coordinate their movements when information is limited to an individual group member's observation of adjacent group member motion, (II whether an informed group minority can lead an uninformed group majority to the minority's goal, and if so, (III how this minority exerts its influence. We showed that in a human group--on the basis of movement alone--a minority can successfully lead a majority. Minorities lead successfully when (a their members choose similar initial steps towards their goal field and (b they are among the first in the whole group to make a move. Using our approach, we empirically demonstrate that the rules of swarming behaviour apply to humans. Even complex human behaviour, such as leadership and directed group movement, follow simple rules that are based on visual perception of local movement.