bluuebunny/crossref_metadata_2025 huggingface dataset:
FORMATIVE ASSESSMENT IN LANGUAGE EDUCATION POLICIES: EMERGING LESSONS FROM WALES AND SCOTLAND
Authors: Leung Constant , Scott Catriona
Published: February 2010

Formative assessment, particularly in the current form known as Assessment for Learning (AfL), has caught the attention of policymakers in many education jurisdictions. Diverse educational systems such as Hong Kong and Western Canada have publicly endorsed the principles and practice of AfL. In the United Kingdom, progressive devolution of state power from London has meant that Scotland and Wales now have national autonomy in education matters. In a dramatic reversal of policy, both of these “home” countries have in the past four years dismantled the heavily test-oriented schooling regime. Instead both the Welsh and Scottish administrations have adopted assessment policies that prioritize learning. This article discusses (1) the political and ideological trajectories that have supported the emergence of the for-learning assessment policies and (2) the fit (or lack of) between AfL principles and the prevailing espoused educational values in these two nations. The potential impact of these developments for assessment of English as an additional/second language (EAL) in schooling education will be discussed.
Turing universality of the Biochemical Ground Form
Authors: CARDELLI LUCA , ZAVATTARO GIANLUIGI
Published: February 2010

We explore the expressive power of languages that naturally model biochemical interactions relative to languages that only naturally model basic chemical reactions, identifying molecular association as the basic mechanism that distinguishes the former from the latter. We use a process algebra, the Biochemical Ground Form (BGF), that adds primitives for molecular association to CGF, which is a process algebra that has been proved to be equivalent to the traditional notations for describing basic chemical reactions. We first observe that, unlike CGF, BGF is Turing universal as it supports a finite precise encoding of Random Access Machines, which comprise a well-known Turing powerful formalism. Then we prove that the Turing universality of BGF derives from the interplay between the molecular primitives of association and dissociation. In fact, the elimination from BGF of the primitives already present in CGF does not reduce the computational strength of the process algebra, but if either association or dissociation is removed, BGF ceases to be Turing complete.
Modal and mixed specifications: key decision problems and their complexities
Authors: ANTONIK ADAM , HUTH MICHAEL , LARSEN KIM G. , NYMAN ULRIK , WĄSOWSKI ANDRZEJ
Published: February 2010

Modal and mixed transition systems are specification formalisms that allow the mixing of over- and under-approximation. We discuss three fundamental decision problems for such specifications:

—

whether a set of specifications has a common implementation;

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whether an individual specification has an implementation; and

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whether all implementations of an individual specification are implementations of another one.

For each of these decision problems we investigate the worst-case computational complexity for the modal and mixed cases. We show that the first decision problem is EXPTIME-complete for both modal and mixed specifications. We prove that the second decision problem is EXPTIME-complete for mixed specifications (it is known to be trivial for modal ones). The third decision problem is also shown to be EXPTIME-complete for mixed specifications.
Managing correlated stock externalities: water taxes with a pinch of salt
Authors: LEGRAS SOPHIE
Published: February 2010

This paper addresses the design of corrective taxation schemes to manage multiple, interacting stocks. In the setting of irrigation-induced salinity, a collective groundwater stock aliments a set of individual rootzone salt stocks. It is shown that the policy maker does not need to base the tax rule on the individual salt stocks. Indeed, taxes based on the level of input and on the collective stock induce the agents to achieve the socially optimal irrigation path. An even simpler instrument is sufficient if the policy-maker's goal is to reach optimality at the steady state only.
Valuing irrigation water using a choice experiment: an ‘individual status quo’ modelling of farm specific water scarcity
Authors: BARTON DAVID N. , BERGLAND OLVAR
Published: February 2010

We use a choice experiment to evaluate a hypothetical irrigation water pricing regime in Karnataka State, India. The proposed regime includes increasing the availability of water in the dry season, increasing irrigation frequency, water sharing with downstream water users, set against the introduction of a semi-volumetric irrigation price. The majority of farmers chose the status quo (SQ) option. Given the large heterogeneity in farmers’ SQ water availability, irrigation practices and current water tax payments, the SQ could not be given a unique baseline interpretation. This poses a potential problem for choice model estimation. By coding the individual SQ situation of farmers, we observed considerable increase in the explanatory power of the choice experiment models. The results may be of general interest for choice experiments of environmental goods and services with heterogeneous spatial distribution, heterogeneous respondents and/or contentious policies that are expected to elicit considerable SQ response.
Irrigation water demand and implications for water pricing policy in rural China
Authors: HUANG QIUQIONG , ROZELLE SCOTT , HOWITT RICHARD , WANG JINXIA , HUANG JIKUN
Published: February 2010

The goal of this paper is to analyze whether reforming groundwater pricing has the potential to encourage water conservation and assess its impacts on crop production and producer income in rural China. Household-level water demands are estimated so that adjustments at both the intensive and extensive margins are captured. The results show that a large gap exists between the cost of water and the value of water to producers. Simulation analysis shows that reforming water pricing can induce water savings. However, the price of water needs to be raised to a relatively high level. We also find that the value-based policy is more effective than the cost-based policy since it generates larger water savings, given the same increase in the average price of water. While raising the price of water negatively affects crop production and crop income, higher water prices do not adversely affect the distribution of household income.
Three-Dimensional Analysis of Carbon Nanotube Networks in Interconnects by Electron Tomography without Missing Wedge Artifacts
Authors: Ke Xiaoxing , Bals Sara , Cott Daire , Hantschel Thomas , Bender Hugo , Van Tendeloo Gustaaf
Published: February 2010

The three-dimensional (3D) distribution of carbon nanotubes (CNTs) grown inside semiconductor contact holes is studied by electron tomography. The use of a specialized tomography holder results in an angular tilt range of ±90°, which means that the so-called “missing wedge” is absent. The transmission electron microscopy (TEM) sample for this purpose consists of a micropillar that is prepared by a dedicated procedure using the focused ion beam (FIB) but keeping the CNTs intact. The 3D results are combined with energy dispersive X-ray spectroscopy (EDS) to study the relation between the CNTs and the catalyst particles used during their growth. The reconstruction, based on the full range of tilt angles, is compared with a reconstruction where a missing wedge is present. This clearly illustates that the missing wedge will lead to an unreliable interpretation and will limit quantitative studies.
Imaging Resin-Cast Osteocyte Lacuno-Canalicular System at Bone-Bioactive Glass Interface by Scanning Electron Microscopy
Authors: Gorustovich Alejandro A.
Published: February 2010

The morphology of the osteocyte lacuno-canalicular system at the bone-biomaterial implant-interface has not been fully investigated. In this study, the resin-cast scanning electron microscopy technique was used, for the first time, to image the lacuno-canalicular network within neoformed bone around bioactive glass (BG) particles implanted in rat tibia bone marrow. The most salient finding was that the osteocyte canaliculi pass through the calcium-phosphorus layer formed at the bone-BG interface and reach the silica-rich layer of the reacted BG.
Therapeutic benefit of radiotherapy after surgery in patients with T1–T2 breast tumour
Authors: Yadav Budhi S. , Sharma Suresh C. , Patel Firuza D. , Bose S.M. , Ghoshal Sushmita , Kapoor Rakesh K.
Published: February 2010

Purpose: To look for the therapeutic benefit of radiotherapy after surgery in patients with T1–T2 breast tumour.

Methodology: From 1990 to 2000, 915 patients with T1–T2 breast tumour who underwent mastectomy or conservative breast surgery (CBS) with or without radiotherapy were analysed retrospectively for age, disease stage, radiation therapy technique, dose, the use of chemotherapy or hormonal therapy and other clinical and/or pathologic characteristics. The Kaplan–Meier method was used to estimate locoregional recurrence-free survival (LRRFS) and overall survival (OS). The Cox proportional hazard regression model was used to determine significant prognostic factors affecting LRRFS and OS.

Results: At a median follow up of 74 months, LRR rate was 5.3% and distant metastases rate was 19%. Disease-free survival (DFS) and OS at 10 year was 72% and 76%, respectively. LRR in patients with CBS followed with radiation was 3% as compared to 33% without radiation. LRR in patients with post-mastectomy radiation was 3% as compared to 19% without radiation. In patients with N0 nodes, LRR was 4% with radiation and 20% without radiation. Worst case was in patients with CBS-N0 who were not given radiation. LRR in such patients was 32% as compared to 5% in those who were given radiation post-CBS. In patients with mastectomy with N0 status, LRR was 3% with radiation as compared to 18% with out radiation. On univariate analysis factors affecting LRRFS were type of surgery, nodal involvement, radiotherapy and hormonal therapy. Factors affecting OS were nodal involvement, grade, lymphovascular invasion (LVI), ductal carcinoma in situ (DCIS), extracapsular extension (ECE), chemotherapy and radiotherapy. On multivariate analysis factors affecting LRRFS were type of surgery, nodal involvement, radiotherapy and hormonal therapy. Factors affecting OS were nodal involvement, LVI, DCIS, ECE, chemotherapy and radiotherapy.

Conclusion: Radiation use offered a therapeutic advantage for all patients with T1–T2 breast cancer.
Citizens' Satisfaction with Government Performance in Six Asian-Pacific Giants
Authors: WANG ZHENGXU
Published: February 2010

Assessment of the quality of governance has so far relied on socioeconomic statistics and expert opinions, while largely neglecting citizens’ perceptions. Using AsiaBarometer 2008 data, this paper examines the factors affecting citizens’ satisfaction with their government in six Asian-Pacific countries: America, Australia, China, India, Japan, and Russia. I found citizen satisfaction with the public services they receive, such as education, healthcare, and public safety, matters most in their assessment of government performance. Individual satisfaction with income, job, and housing also matters. The respondent will disapprove government performance if he or she thinks corruption is serious in government, or elected officials stop caring about citizens once voting is finished. In terms of macro variables, economic condition of a country seems to matters significantly. Especially, if a country's economy is growing fast, citizens are much more likely to be satisfied with government performance. Large within-country variations exist in countries such as China and India, where citizens of different cities or regions may give rather different assessments of government, suggesting many contextual variables not captured by this study. Lastly, citizens’ satisfaction with government performance seems to be highly divergent from international organizations’ evaluation of governance quality, such as the World Bank Governance Index. This raises both methodological and normative issues regarding the proper approaches to measuring good governance.
ART AND LIFE IN AVANT-GARDE PRAGUE, 1920–1924
Authors: ORT THOMAS
Published: February 2010

This essay outlines the unique interpretation of the avant-garde formulated in the early 1920s by the Czech novelist, playwright, and cultural critic Karel Čapek (1890–1938). Whereas inTheory of the Avant-Garde(1974) Peter Bürger argued that the central problem of the avant-garde was its failure to effect a genuine reconciliation of art and life, Čapek, in contrast, worried about the prospect of success. Closely observing the practices of the Czech avant-garde group Devětsil, Čapek interpreted its attempt to fuse art and life in terms derived largely from the French vitalist philosopher Henri Bergson (1859–1941) as an effort to free life from all constraints and bonds. Drawing on the work of Georg Simmel (1858–1918), he argued that the goal of living life “in itself,” without any constraints, was impossible. All life, he said, must necessarily be embodied in form and so less than completely free. Life conceived as a state of pure freedom, unbounded by any material or physical limits, amounted to the devaluation of individual life. The problem with the project of the avant-garde was that it was unethical.
THE POLIS AND ITS ANALOGUES IN THE THOUGHT OF HANNAH ARENDT
Authors: MARSHALL DAVID L.
Published: February 2010

Criticized as a nostalgic anachronism by those who oppose her version of political theory and lauded as symbol of direct democratic participation by those who favor it, the Athenian polis features prominently in Hannah Arendt's account of politics. This essay traces the origin and development of Arendt's conception of the polis as a space of appearance from the early 1950s onward. It makes particular use of theDenktagebuch, Arendt's intellectual diary, in order to shed new light on the historicity of one of her central concepts. The article contends that both critics and partisans of Arendt's use of the polis have made the same mistake: they have presumed that the polis represents a space of face-to-face immediacy. In fact, Arendt compared the polis to a series of analogues, many of which are not centered on direct exchanges between political actors and spectators. As a result, Arendt's early work on the polis turns out to anticipate many of the concerns of her later work on judgment, and her theory of the polis becomes a theory of topics.
IMPERIAL LIBERALISM? RELIGION, EDUCATION, AND THE COLD WAR
Authors: COUVARES FRANCIS G.
Published: February 2010

A few years ago I found myself at the Ogden, Utah rodeo with thirty schoolteachers from all over the world. They were participants in a Fulbright-supported American studies institute, and the trip to Utah was part of a weeklong foray into a part of America quite different from Amherst, MA, where the bulk of lectures and discussions had taken place in the previous three weeks. Our visit happened to coincide with “Armed Services Day,” and the spectacle my students encountered proved even more impressive than the riding and roping they had expected. The principle feature of that spectacle had to do with the organizers’ almost total confounding of religion and patriotism. At the high point of the event, over the roar of military band music and military helicopters passing overhead, the booming voice of the announcer declared that “God's helicopters” were protecting America and the rest of the world from tyranny. The books under review here endeavor to explain the spectacle in Ogden on that summer day—along with the train of events that, over sixty years ago, launched a crusade against “godless communism” and, a few decades later, made “the Christian right” a major force in American politics.
Helioseismic inferences
Authors: Shibahashi Hiromoto
Published: February 2010

The brilliant outcome of some 30 years of helioseismology spreads over a wide range of topics. Some highlights relevant to the cause of the solar activity cycle are listed up. The rotation profile in the solar convective zone is discussed as an important source of the dynamo mechanism. The kinematic dynamo model is described in the linear approximation, and the condition for the solar type dynamo is derived. It is shown that comparison of this condition with the rotation profile determined from helioseismology is useful to identify the possible seats of the dynamo.
A solar cycle lengthwise series of solar diameter measurements
Authors: Penna J. L. , Andrei A. H. , Boscardin S. C. , Neto E. Reis , d'Ávila V. A.
Published: February 2010

The measurements of the solar photospheric diameter rank among the most difficult astronomic observations. Reasons for this are the fuzzy definition of the limb, the SNR excess, and the adverse daytime seeing condition. As a consequence there are very few lengthy and consistent time series of such measurements. Using modern techniques, just the series from the IAG/USP and from Calern/OCA span more than one solar cycle. The Rio de Janeiro Group observations started in 1997, and therefore in 2008 one complete solar cycle time span can be analyzed. The series shares common principles of observation and analysis with the ones afore mentioned, and it is complementary on time to them. The distinctive features are the larger number of individual points and the improved precision. The series contains about 25,000 single observations, evenly distributed on a day-by-day basis. The typical error of a single observation is half an arc-second, enabling us to investigate variations at the expected level of tens of arc-second on a weekly basis. These features prompted to develop a new methodology for the investigation of the heliophysical scenarios leading to the observed variations, both on time and on heliolatitude. The algorithms rely on running averages and time shifts to derive the correlation and statistical incertitude for the comparison of the long term and major episodes variations of the solar diameter against activity markers. The results bring support to the correlation between the diameter variation and the solar activity, but evidentiating two different regimens for the long term trend and the major solar events.
Solar-like stars seismology
Authors: Pricopi Dumitru , Suran Marian Doru
Published: February 2010

Many solar like stars were observed by CoRoT and MOST missions. We try to investigate some of these stars using asteroseismic inversion method using both frequencies fitting and separation fitting. Our results are compared with semiempirical method based on direct power spectrum analysis.
Sounding stellar cycles with Kepler – preliminary results from ground-based chromospheric activity measurements
Authors: Karoff C. , Metcalfe T. S. , Chaplin W. J. , Frandsen S. , Grundahl F. , Kjeldsen H. , Buzasi D. , Arentoft T. , Christensen-Dalsgaard J.
Published: February 2010

Due to its unique long-term coverage and high photometric precision, observations from the Kepler asteroseismic investigation will provide us with the possibility to sound stellar cycles in a number of solar-type stars with asteroseismology. By comparing these measurements with conventional ground-based chromospheric activity measurements we might be able to increase our understanding of the relation between the chromospheric changes and the changes in the eigenmodes.

In parallel with the Kepler observations we have therefore started a programme at the Nordic Optical Telescope to observe and monitor chromospheric activity in the stars that are most likely to be selected for observations for the whole satellite mission. The ground-based observations presented here can be used both to guide the selection of the special Kepler targets and as the first step in a monitoring programme for stellar cycles. Also, the chromospheric activity measurements obtained from the ground-based observations can be compared with stellar parameters such as ages and rotation in order to improve stellar evolution models.
A comparison of measured and simulated solar network contrast
Authors: Afram N. , Unruh Y. C. , Solanki S. K. , Schüssler M. , Mathew S. K.
Published: February 2010

Long-term trends in the solar spectral irradiance are important to determine the impact on Earth's climate. These long-term changes are thought to be caused mainly by changes in the surface area covered by small-scale magnetic elements. The direct measurement of the contrast to determine the impact of these small-scale magnetic elements is, however, limited to a few wavelengths, and is, even for space instruments, affected by scattered light and instrument defocus. In this work we calculate emergent intensities from 3-D simulations of solar magneto-convection and validate the outcome by comparing with observations from Hinode/SOT. In this manner we aim to construct the contrast at wavelengths ranging from the NUV to the FIR.
Semi-harmonic and intermittent solar decimetric spikes
Authors: Fernandes Francisco C. R. , Bolzan Maurício J. A. , Rosa Reinaldo R. , Dutra José A. S. S. , Cecatto José R. , Mészárosová Hana , Sawant Hanumant S.
Published: February 2010

We present the analysis of the narrowband solar radio spike emissions observed by the Brazilian Solar Spectroscope (BSS) on 24 June, 1999, at 16:53:55–16:56:48 UT. The data were recorded with temporal resolution of 50 ms and frequency resolution of 5 MHz. The dynamic spectra of clusters of spikes were recorded in 100 channels in the 1.2-1.7 GHz frequency band. The groups of radio spikes observed clearly show spectral semi-harmonic structures and an intermittent temporal patter. The observational parameters were determined from the dynamic spectra analysis. The wavelet analysis technique able us to determine the temporal cadence for the clusters. The frequency ratio between two clusters of spikes recorded at same time were inferred. The preliminary results show average cadence of clusters of spikes occurrence of about 32 seconds and a semi-harmonic average frequency ratio of the order of 1:1.2.
The periodic variation of 6.7 days for total solar radiation
Authors: Gan W. Q. , Li Y. P.
Published: February 2010

Analyzing the power spectrum of Total Solar Irradiance (TSI) for the period from 2003 February 25 to 2009 July 6, observed with the Total Irradiance Monitor (TIM) onboard SOlar Radiation and Climate Experiment (SORCE), we found that there are quite a number of periodic variations. The outstanding shortest one is the period of 6.7 days, about one fourth of the period of solar rotation. Checking the solar magnetic field for the same period of time observed with MDI onboard SOHO, we found that there is about 90 degree difference in longitude for the distribution of solar magnetic field. We therefore conclude that both the 90 degree difference in longitude for the distribution of solar magnetic field and the solar rotation are the reason resulting in the periodic variation of 6.7 days for the total solar radiation.
Looking for variable stars in galactic open clusters
Authors: Greco Claudia , Mowlavi Nami , Eyer Laurent , Spano Maxime , Varadi Mihaly , Burki Gilbert
Published: February 2010

A long-term project, aiming at systematic search for variable stars in Galactic Open Clusters (OCs), was started at the Geneva Observatory in 2002. We have been observing regularly a sample of twenty-seven Galactic Open Clusters in the U, B, V Geneva filters (hereafter U, B, V). The goal is to identify and to study their variable stars, as well as the connection between the variable stars in a cluster and the cluster properties. We present the status of this work in progress, and show preliminary results for one of these clusters, IC 4651.
Doppler imaging of the active star PW And
Authors: Gu Sheng-hong , Cameron Andrew Collier , Kim Kang Min
Published: February 2010

We present spot activity of the K2V pre-main-sequence star PW And based on the high-resolution spectroscopic data obtained at Xinglong station and BOAO in 2005 November and December. Using the Least-Squares Deconvolution method, we have derived time series of composite profiles of PW And with high signal to noise ratio. These have been used to reconstruct its starspot pattern via the Doppler imaging method. The result shows that intermediate to high-latitude spots are the dominant features and weak low-latitude spots also appear. Comparing Doppler images from two data subsets, it can be found that almost no difference between two images exists except the small position evolution of weak low-latitude spots, which suggests that the intermediate to high-latitude spots have longer lifetimes than one month, and the low-latitude spots have shorter lifetimes.
Coronal magnetic fields from the inversion of linear polarization measurements
Authors: Liu Yu , Lin Haosheng , Kuhn Jeff
Published: February 2010

Real 3-D coronal magnetic field reconstruction is expected to be made based on the technologies of IR spectrometry and tomography, in which the data from other wavelengths can be used as critical reference. Our recent studies focused on this issue are briefly reviewed in this paper. Liu & Lin (2008) first evaluated the validity of potential field source surface model applied to one of five limb regions in the corona by comparing the theoretical polarization maps with SOLARC observations in the IR Fe XIII 10747 Å forbidden coronal emission line (CEL). The five limb coronal regions were then studied together in order to study the spatial relation between the bright EUV features on the solar disk and the inferred IR emission sources, which were obtained from the inversion of the SOLARC linear polarization (LP) measurements (Liu 2009). The inversion for each fiber data in the field of view was made by finding the best location where the difference between the synthesized and the observed polarizations reaches the minimum in the integration path along the line of sight. We found a close relationship between the inferred IR emission source locations and the EUV strong emission positions.
Observation of interactions between two erupting filaments
Authors: Liu Yu , Su Jiangtao , Shen Yuandeng , Yang Liheng
Published: February 2010

Following the first observational study of the interaction between two distinct filaments (Su et al. 2007; hereafter, event 1), we present another interesting case observed by SMART telescope on 2005 June 25 with higher spatial resolution (hereafter, event 2). The two events are compared with each other. In event 1 the two filaments erupted subsequently and obvious mass flow was observed to be transferred from one erupting filament to one stable filament which triggered its eruption. On the contrary, in event 2, the two filaments erupted simultaneously and there was no transfer of material noticed between them during the initial stage. The two filaments merged together along the ejection path, indicating the bodily coalesce between the two interacting flux ropes. Moreover, event 1 was associated with a coronal mass ejection (CME), while event 2 was a failed filament eruption, thus without CME association.
Study of helicity properties of peculiar active regions
Authors: Fuentes M. C. López , Mandrini C. H. , Démoulin P.
Published: February 2010

Peculiar solar active regions (ARs), such as δ-islands and other high tilt bipoles, are commonly associated with the emergence of severely deformed magnetic flux tubes. Therefore, the study of these ARs provides valuable information on the origin and evolution of magnetic structures in the solar interior. Here, we infer the magnetic helicity properties of the flux tubes associated to a set of peculiar ARs by studying the evolution of photospheric magnetograms (SOHO/MDI) and coronal observations (SOHO/EIT and TRACE) in combination with force-free models of the magnetic field. We discuss how our results relate to different models of the evolution of emerging magnetic flux tubes.
Stellar magnetic cycles
Authors: Lanza A. F.
Published: February 2010

The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. The detection of activity cycles in solar-like stars and the study of their properties allow us to put the solar dynamo in perspective, investigating how dynamo action depends on stellar parameters and stellar structure. Nevertheless, the lack of spatial resolution and the limited time extension of stellar data pose limitations to our understanding of stellar cycles and the possibility to constrain dynamo models. I briefly review some results obtained from disc-integrated proxies of stellar magnetic fields and discuss the new opportunities opened by space-borne photometry made available by MOST, CoRoT, Kepler, and GAIA, and by new ground-based spectroscopic or spectropolarimetric observations. Stellar cycles have a significant impact on the energetic output and circumstellar magnetic fields of late-type active stars which affects the interaction between stars and their planets. On the other hand, a close-in massive planet could affect the activity of its host star. Recent observations provide circumstantial evidence of such an interaction with possible consequences for stellar activity cycles.
Do young Suns undergo magnetic reversals?
Authors: Marsden Stephen C. , Jeffers Sandra V. , Donati Jean-Francois , Mengel Matthew W. , Waite Ian A. , Carter Brad D.
Published: February 2010

A key part of the modern-day regenerative solar magnetic dynamo is the reversal of the Sun's global magnetic field every eleven years. However, recent theoretical models indicate that young-rapidly rotating Sun-like stars may not always undergo full magnetic reversals, but instead may sometimes undergo “attempted” reversals where the magnetic field declines in strength only to return with the same polarity. Using the technique of Zeeman Doppler imaging we have mapped the magnetic field topology of a small sample of young Sun-like stars at multiple epochs, and present tentative evidence of an “attempted” magnetic field reversal on one of our stars.
Long-term stellar variability
Authors: Pagano Isabella
Published: February 2010

Stars with significant subsurface convection zones develop magnetic loop structures that, arising from the surface upward to the external atmospheres, cause flux variability detectable throughout the whole electromagnetic spectrum. In fact, diagnostics of magnetic activity are in radio wavelengths, where gyrosincrotron radiation arises from the quiescent and flaring corona; in the optical region, where important signatures are the Balmer lines, the Ca ii IRT and H&K lines; in the UV and X ray domains, the latter mainly due to coronal thermal plasma. The zoo of different magnetic features observed for the Sun – spots, faculae, flares, CMEs – are characterized by different temporal evolution and energetics, both in quantity and quality. As a consequence, the time scale of variability, the amount of involved energy and the quality of the involved photons are used as fingerprints in interpreting the observed stellar variability in the framework of the solar-stellar analogy. Here I review main results from long-term multiwavelength observations of cool star atmospheres, with emphasis to similarities and differences with the solar case.
The Cycles of Alpha Centauri
Authors: Ayres Thomas R.
Published: February 2010

The main AB pair of the nearby Alpha Centauri triple system has one of the most extensive X-ray records of any cosmic object, stretching over three decades. The primary, α Cen A (G2V), is a near twin of the Sun, with a similarly soft (1–2 MK) corona. The secondary, α Cen B (K1V), is more active than the Sun, with a generally harder coronal spectrum. Here, spatially resolved measurements of the pair by Chandra's High Resolution Camera are compared, on a common basis, with previous pointings from ROSAT and XMM-Newton.
Harmonic analysis approach to solar cycle prediction and the Waldmeier effect
Authors: Petrovay K.
Published: February 2010

It is demonstrated that, in addition to the precursor method, harmonic analysis approach to solar cycle prediction is also strongly conditioned by the Waldmeier effect.
Solar cycles: the past evolution influence
Authors: Klutsch Alexis , Ferrero Rubens Freire
Published: February 2010

The so-calledsolar cycleis generally characterized by the quasi-periodic oscillatory evolution of the photospheric spots number. This quasi-periodic pattern has always been an intriguing question. Several physical models were proposed to explain this evolution and many mathematical data analysis were employed to determine the principal frequencies noticeable in the measured data. Both approaches try to predict the future evolution of the solar activity and to understand the physical phenomena producing these cycles. Here we present the analysis of the sunspots number evolution using the time-delay approach. Our results show than the solar cycle can also be characterized by this behavior implying the influence of the past evolution over the present one, suggesting an histeresis mechanism, linked probably with magnetic activity.
Prediction of solar activity cycles by assimilating sunspot data into a dynamo model
Authors: Kitiashvili Irina N. , Kosovichev Alexander G.
Published: February 2010

Solar activity is a determining factor for space climate of the Solar system. Thus, predicting the magnetic activity of the Sun is very important. However, our incomplete knowledge about the dynamo processes of generation and transport of magnetic fields inside Sun does not allow us to make an accurate forecast. For predicting the solar cycle properties use the Ensemble Kalman Filter (EnKF) to assimilate the sunspot data into a simple dynamo model. This method takes into account uncertainties of both the dynamo model and the observed sunspot number series. The method has been tested by calculating predictions of the past cycles using the observed annual sunspot numbers only until the start of these cycles, and showed a reasonable agreement between the predicted and actual data. After this, we have calculated a prediction for the upcoming solar cycle 24, and found that it will be approximately 30% weaker than the previous one, confirming some previous expectations. In addition, we have investigated the properties of the dynamo model during the solar minima, and their relationship to the strength of the following solar cycles. The results show that prior the weak cycles, 20 and 23, and the upcoming cycle, 24, the vector-potential of the poloidal component of magnetic field and the magnetic helicity substantial decrease. The decrease of the poloidal field corresponds to the well-known correlation between the polar magnetic field strength at the minimum and the sunspot number at the maximum. However, the correlation between the magnetic helicity and the future cycle strength is new, and should be further investigated.
Surface temperature maps for II Peg during 1999–2002
Authors: Lindborg M. , Korpi M. J. , Tuominen I. , Hackman T. , Ilyin I. , Piskunov N.
Published: February 2010

The active RS CVn star II Peg has been spectroscopically monitored for almost 18 years with the SOFIN spectrograph at NOT, La Palma, Spain. In this paper we present five new surface temperature maps of the object for the years 1999 (two maps), 2001 (one map) and 2002 (two maps).
‘Negative’ surface differential rotation in stars having low Coriolis numbers (slow rotation or high turbulence)
Authors: Chan Kwing L.
Published: February 2010

A general picture of differential rotation in cool stars is that they are ‘solar-like’, with the equator spinning faster than the poles. Such surface differential rotation profiles have also been demonstrated by some three-dimensional simulations. In our numerical investigation of rotating convection (both regional and global), we found that this picture is not universally applicable. The equator may spin substantially slower than the poles (Ωequator − Ωpole)/Ω can reach −50%). The key parameter that determines the transition in behavior is the Coriolis number (inverse Rossby number). ‘Negative’ differential rotation of the equator (relative to the mean rotation) occurs if the Coriolis number is below a critical value.
Is there more global solar activity on the Sun?
Authors: Wang J. X. , Zhang Y. Z. , Zhou G. P. , Wen Y. Y. , Jiang J.
Published: February 2010

There appear indications of more global activity on the Sun which is larger, much beyond the scale of solar active regions (ARs). These indications include formation, flaring and eruption of the trans-equatorial loops seen in EUV and X-rays, formation and eruption of trans-equatorial filaments, global magnetic connectivity in EUV dimming associated with halo-coronal mass ejections, wide spread of radio burst sources in meter wavelength in the solar corona, and quasi-simultaneous magnetic flux emergence in both hemispheres seen during some major solar events. With examples of a few major events in the last solar cycle we discuss the possibility that there is large or global-scale activity on the Sun. Its spatial scale is many times larger than that of AR and temporal scale is over 10 hours. The exemplified trans-equatorial loops are anchored in ARs and their activity is temporally associated with flares in ARs too. In some sense the flares in ARs appear either as a part of or a precursor of the more global activity. It is likely that the combination of the flares in ARs and the associated global activity is responsible to the major solar-terrestrial events. More efforts in understanding the global activity are undertaken.
Magnetic energy release: flares and coronal mass ejections
Authors: Mandrini Cristina H.
Published: February 2010

Free energy stored in the magnetic field is the source that powers solar and stellar activity at all temporal and spatial scales. The energy released during transient atmospheric events is contained in current-carrying magnetic fields that have emerged twisted and may be further stressed via motions in the lower atmospheric layers (i.e. loop-footpoint motions). Magnetic reconnection is thought to be the mechanism through which the stored magnetic energy is transformed into kinetic energy of accelerated particles and mass flows, and radiative energy along the whole electromagnetic spectrum. This mechanism works efficiently at scale lengths much below the spatial resolution of even the highest resolution solar instruments; however, it may imply a large-scale restructuring of the magnetic field inferred indirectly from the combined analysis of observations and models of the magnetic field topology. The aftermath of magnetic energy release includes events ranging from nanoflares, which are below our detection limit, to powerful flares, which may be accompanied by the ejection of large amounts of plasma and magnetic field (so called coronal mass ejections, CMEs), depending on the amount of total available free magnetic energy, the magnetic flux density distribution, the magnetic field configuration, etc. We describe key observational signatures of flares and CMEs on the Sun, their magnetic field topology, and discuss how the combined analysis of solar and interplanetary observations can be used to constrain the flare/CME ejection mechanism.
The mechanism of the light variability of chemically peculiar stars
Authors: Krtička J. , Mikulášek Z. , Zverko J. , Žižňovský J. , Henry G. W. , Skalický J. , Zvěřina P.
Published: February 2010

Until recently, the mechanism of the light variability of chemically peculiar (CP) stars was unclear. To improve this situation, we started a theoretical and observational campaign aimed at the nature of the light variability of these stars. We use the TLUSTY model atmospheres calculated for the appropriate surface chemical composition to obtain the emergent flux and to predict the rotationally modulated light curves. We show on example of several well-studied CP stars that their light variations can be explained as a result of i) the uneven surface distribution of the elements (creating overabundant regions), ii) the flux redistribution from the ultraviolet to the visible part of the spectrum (in the overabundant regions), and iii) rotation of the star. We show that the silicon and helium bound-free transitions and iron bound-bound transitions provide the main contribution to the flux redistribution. This result is also a very precise test of modern stellar model atmospheres. We conclude that the mentioned mechanism is a very promising explanation for the light variations in CP stars of earlier spectral types.
Analysis of the event of 2004 November 10
Authors: Ma Yuan , Zhu LiYing
Published: February 2010

The large burst of complex type which occurred at the metric, decimetric and microwave wavelengths from 0203 to 0304 UT on 2004 November 10 is analyzed in this present article, some prominent features of this event are obtained from the correlative analysis of this event with the Hα flare and coronal mass ejection (CME) and the radiation process of this event is discussed based on these observational features.
Study of the structures of the explosive events in the UV
Authors: Niembro-Hernandez R. T. , Mendoza-Torres J. E. , Wilhelm K.
Published: February 2010

We analyze Si iv 139.37 nm emission line during solar Explosive Events (EE) near the center of the solar disk with the aim to study the structure of the sources of EEs observed at the VUV. The observations were made by SUMER, on board SoHO, with a raster regime of six EW positions that allowed us to identify the times and EW, NS positions of the maximum amplitude of each EE. Based on one dimensional NS distributions at three different wavelengths (blue, central and red) for times around each maximum we have identified three different shapes of the sources. Also, It was found that the maximum at the blue wing is attained after the maxima at red and central wavelengths.
Nonlinear analysis of decimetric solar bursts
Authors: Rosa Reinaldo R. , Bolzan Mauricio J. A. , Fernandes Francisco C. R. , Sawant H. S. , Karlický Marian
Published: February 2010

The solar radio emissions in the decimetric frequency range (above 1 GHz) are very rich in temporal and spectral fine structures due to nonlinear processes occurring in the magnetic structures on the corresponding active regions. In this paper we characterize the singularity spectrum, f(α), for solar bursts observed at 1.6, 2.0 and 3 GHz. We interpret our findings as evidence of inhomogeneous plasma turbulence driving the underlying plasma emission process and discuss the nonlinear multifractal approach into the context of geoeffective solar active regions.
Plasma heating in the initial phase of solar flares
Authors: Rudawy P. , Siarkowski M. , Falewicz R.
Published: February 2010

In this paper we analyze soft and hard X-ray emission of the 2002 September 20 M1.8 GOES class solar flare observed by RHESSI and GOES satellites, where soft X-ray emission precedes the onset of the main bulk hard X-ray emission by ~5 min. This suggests that an additional heating mechanism may be at work at the early beginning of the flare. However RHESSI spectra indicate presence of the non-thermal electrons also before impulsive phase. So, we assumed that a dominant energy transport mechanism during rise phase of solar flares is electron beam-driven evaporation. We used non-thermal electron beams derived from RHESSI spectra as the heating source in a hydrodynamic model of the analyzed flare. We showed that energy delivered by non-thermal electron beams is sufficient to heat the flare loop to temperatures in which it emits soft X-ray closely following the GOES 1–8 Å light-curve.
Stellar flare diagnostics from multi–wavelength observations
Authors: Stepanov Alexander V. , Tsap Yuri T. , Kopylova Yulia G.
Published: February 2010

Quasi–periodic pulsations in various wavebands are natural manifestations of emission of stellar flares. We suggest a diagnostic tool of stellar flares based on the coronal seismology and the solar–stellar analogy. Two approaches are used: (I) flare loop as a resonator for MHD oscillations and (II) flare loop as an equivalent electric circuit. Using optical, X–ray, and radio data we obtained flare plasma parameters for the red dwarfs EQ Peg, AT Mic, and AD Leo. The characteristic length of stellar flare loops l ~ R* and their electric currents turned out to be one–two orders of magnitude lager than the solar ones. Advantages of proposed diagnostics in comparison to the scaling law methods are given.
The non-radial propagation of coronal streamers in minimum activity epoch
Authors: Tlatov Andrey G. , Vasil'eva Valeria V.
Published: February 2010

We have analyzed the shape of the solar corona using the data of daily observations with Mark-3/4 (1980-2008) and SOHO/Lasco-2 (1996–2008) telescopes. The angles of deviation of coronal rays from the radial direction Δθ vary cyclically, reaching the maximum deviation towards the solar equator at the minimum of the solar activity. At the minimum of the 24-th cycle of activity, the Δθ angles were smaller than they were at the minimum of the 22-nd and 23-rd cycles.

We also analyzed of the solar structure corona during eclipses for minimum activity from 1870 till 2008. We examined changes in the index, which characterizes the angle of large coronal streamers to the equatorial plane. It has been shown that the index has been smoothly changing during the last 140 years. The maximal value of an index was during 17–19 activity cycles. The minimal values are reached in the end of 19 centuries and at the present time.

We consider the relations between the angles of deviation of coronal rays at the minimum of activity, the parameters of the global magnetic field of the Sun, and the amplitude of the subsequent cycle of activity, and discuss the hypothesis that the variations of the inclination of coronal rays may affect the parameters of the solar wind and the indices of geomagnetic perturbations at the minima of the solar activity cycles.
New findings increasing solar trend that can change Earth climate
Authors: Rozelot Jean-Pierre , Damiani Cilia , Lefebvre Sandrine
Published: February 2010

Early attempts to find how solar activity can influence the Earth's climate involved comparison of many physical processes, such as dynamo mechanism, magnetic reconnection and eruptive activity, irradiance, open flux and particles variations, global atmospheric chemistry and dynamics.. . . However, such direct links seem to be weak even if the solar effects has been found to be stronger during extended maxima or minima of solar activity. Thus, temporal scales ranging from days to thousand of years must be investigated. A description of the most recent results on solar variability and its possible influence on the Earth's climate and atmosphere will be here addressed, with a particular emphasize on modulations of about 120 years (and harmonics). The extrapolation indicates a significant negative decrease of the solar signal, and consequently a decrease of the global Earth's temperature in the forthcoming years. Such a modulation is also testifying by other means, such as spectral observations of temperature sensitive lines indicating a decline of solar activity around 2015 (up to a new prolonged minimum). Prediction of global effects from the Sun's influence over the climate is thus planted in a new way.
Are there variations in Earth's global mean temperature related to the solar activity?
Authors: Kjeldseth-Moe Olav , Wedemeyer-Böhm Sven
Published: February 2010

We have analyzed the record of Earth's global temperature variations between 1850 and 2007 looking for signals of periodic variations and compared our results with solar activity variations in the same time period. Significant periods are found at 9.4, 10.6 and 20.9 years. These periodic variations may be caused by solar activity. However, and amazingly enough, we also find at least 17 other significant periodic variations in addition to expected variations with periods of 1 year and of half a year. The result is considered in terms of solar related forcing mechanisms. These may be variable solar heating associated with the small changes in solar irradiance over the solar cycle, or direct effects of interactions between variable magnetic fields carried by the solar wind and particles and fields in interplanetary space or in the Earth's ionosphere.