bluuebunny/crossref_metadata_2025 huggingface dataset:
Age-related decline in macrophage and lymphocyte functions in mice and its alleviation by treatment with probiotic Dahi containingLactobacillus acidophilusandBifidobacterium bifidum
Authors: Kaushal Deepti , Kansal Vinod K
Published: August 2011

This study evaluated the effects of probiotic Dahi administration in ageing mice on macrophage and lymphocyte functions. Probiotic Dahi were prepared by co-culturing in buffalo milk (3% fat) Dahi bacteria (Lactococcus lactisssp.cremorisNCDC-86 andLc. lactisssp.lactisbiovardiacetylactisNCDC-60) along withLactobacillus acidophilusLaVK2 (La-Dahi) or combinedLb. acidophilusandBifidobacterium bifidumBbVK3 (LaBb-Dahi). Four groups of 12 mo old mice were fed for four months, with the supplements (5 g/day) of buffalo milk (3% fat), Dahi, La-Dahi and LaBb-Dahi, respectively, in addition to basal diet, and a fifth group that received no supplements served as control. The immune functions of young mice (4 mo old) were also compared with those of ageing adult mice (16 mo old). The production of nitric oxide and cytokines IL-6 and TNF-α declined and that of immunosuppressive prostaglandin E2(PGE2) increased by stimulated peritoneal and splenic macrophages in ageing mice, compared with their young counterparts. The proliferation of stimulated splenocytes diminished and the production of IL-2 decreased and that of IL-6 and TNF-α enhanced in ageing compared with young mice. Feeding ageing mice with La-Dahi or LaBb-Dahi improved peritoneal macrophage functions stimulating nitric oxide and IL-6 and diminishing PGE2production. Feeding La-Dahi or LaBb-Dahi also improved lymphocyte functions stimulating their proliferation and production of IL-2 in ageing mice. To conclude, the probiotic La-Dahi and LaBb-Dahi are effective in reversing age related decline in immune functions in mice.
Probiotic lactobacilli and bifidobacteria in a fermented milk product with added fruit preparation reduce antibiotic associated diarrhea andHelicobacter pyloriactivity
Authors: de Vrese Michael , Kristen Holger , Rautenberg Peter , Laue Christiane , Schrezenmeir Jürgen
Published: August 2011

To investigate matrix-specifity of probiotic effects and particularly of the reduction of antibiotics-associated diarrhea, a controlled, randomized, double-blind study was performed, in which 88Helicobacter pylori-infected but otherwise healthy subjects were given for eight weeks either a) a probiotic fruit yoghurt “mild” containingLactobacillus acidophilusLA-5 plusBifidobacterium lactisBB-12,n=30), b) the same product but pasteurized after fermentation (n=29) or c) milk acidified with lactic acid (control,n=29). During week five, aHelicobactereradication therapy was performed.Helicobacteractivity was measured via13C-2-urea breath tests and antibiotic-associated diarrhoea and other gastrointestinal complaints were recorded by validated questionnaires. In intervention group a, b and c the mean number of days with diarrhoea was 4, 10 and 10 (P<0·05), the frequency of episodes 17%, 7% and 27% (n.s.), and the change in total symptoms score before antibiotics treatment was −1·4±1·1, −1·2±1·1, 2·6±1·1 points/four weeks (P<0·05). All milk products decreasedHelicobacteractivity by 18 to 45% without significant differences between groups. The observed decrease inHel. pyloriactivity seems to be not or not only due to probiotic bacteria but (rather) to components of acidified milk (most probably lactic acid). Fruit-yogurt-like fermented milk products with living probiotic bacteria significantly shorten the duration of antibiotics-associated diarrhoea and improve gastrointestinal complaints. Fruit yogurt-like fermented milk is a matrix suitable for probiotic bacteria.
Quality of information available on the World Wide Web for patients undergoing thyroidectomy: review
Authors: Muthukumarasamy S , Osmani Z , Sharpe A , England R J A
Published: August 2011

Introduction:

This study aimed to assess the quality of information available on the World Wide Web for patients undergoing thyroidectomy.

Methods:

The first 50 web-links generated by internet searches using the five most popular search engines and the key word ‘thyroidectomy’ were evaluated using the Lida website validation instrument (assessing accessibility, usability and reliability) and the Flesch Reading Ease Score.

Results:

We evaluated 103 of a possible 250 websites. Mean scores (ranges) were: Lida accessibility, 48/63 (27–59); Lida usability, 36/54 (21–50); Lida reliability, 21/51 (4–38); and Flesch Reading Ease, 43.9 (2.6–77.6).

Conclusion:

The quality of internet health information regarding thyroidectomy is variable. High ranking and popularity are not good indicators of website quality. Overall, none of the websites assessed achieved high Lida scores. In order to prevent the dissemination of inaccurate or commercially motivated information, we recommend independent labelling of medical information available on the World Wide Web.
Duplicate internal auditory canals with facial and vestibulocochlear nerve dysfunction
Authors: Kew T Y , Abdullah A
Published: August 2011

Objective:

We report an extremely rare case of duplication of the internal auditory canal associated with dysfunction of both the facial and vestibulocochlear nerves. We also review the literature regarding the integrity of the facial and vestibulocochlear nerves in such cases.

Case report:

A 34-year-old man presented with unilateral, right-sided, sensorineural hearing loss and facial nerve palsy since childhood. Facial nerve function was observed to be House–Brackmann grade III. Computed tomography and magnetic resonance imaging demonstrated ipsilateral duplicate, vacant internal auditory canals. Based on the clinical presentation, we interpreted these radiological findings as aplasia of the vestibulocochlear nerve and severe hypoplasia of the facial nerve.

Conclusion:

To our best knowledge, this is the first report of vestibulocochlear nerve aplasia and severe facial nerve hypoplasia in a case of ipsilateral duplication of the internal auditory canal. High resolution gradient echo magnetic resonance imaging sequences are advocated for assessment of neural integrity in patients with an abnormal internal auditory canal and facial and/or vestibulocochlear nerve dysfunction.
Functional results of pharyngo-laryngectomy and total laryngectomy: a comparison
Authors: Gadepalli C , de Casso C , Silva S , Loughran S , Homer J J
Published: August 2011

Objective:

To compare the key functional results (regarding swallowing and voice rehabilitation) in patients treated by pharyngo-laryngectomy with flap reconstruction, versus standard, wide-field, total laryngectomy.

Method:

We studied 97 patients who had undergone total laryngectomy and pharyngo-laryngectomy with flap reconstruction. The main outcome measures were swallowing (i.e. solid food, soft diet, fluid or enteral feeding) and fluent voice development.

Results:

There were 79 men and 18 women, with follow up of one to 19 years. Voice (p = 0.037) and swallowing (p = 0.041) results were significantly worse after circumferential pharyngo-laryngectomy than after non-circumferential pharyngo-laryngectomy. There was no significant difference in voice (p = 0.23) or swallowing (p = 0.655) results, comparing total laryngectomy and non-circumferential pharyngo-laryngectomy. The presence of a post-operative fistula significantly influenced voice (p = 0.001) and swallowing (p = 0.009) outcomes.

Conclusion:

The additional measures involved in pharyngo-laryngectomy do not confer any functional disadvantage, compared with total laryngectomy, but only if the procedure is non-circumferential. Functional results of circumferential pharyngo-laryngectomy are worse than those of both non-circumferential pharyngo-laryngectomy and total laryngectomy. If oncologically possible and safe, it is better to keep a pharyngo-laryngectomy non-circumferential.
The Pleasures and Anxieties of Being in the Middle: Emerging Middle-Class Identities in Urban South India
Authors: DICKEY SARA
Published: August 2011

Recent economic changes in India have coincided with a dramatic change in the concept of a ‘middle class’ in the south Indian city of Madurai. Whereas previous sets of class identities were overwhelmingly dichotomous (for example, the rich and the poor, or the ‘big people’ and ‘those who have nothing’), the middle class has now become a highly elaborated component of local class structures and identities. It is also a contested category; moreover, its indigenous boundaries differ from those most often used by scholars, marketers, or policy-makers. Drawing from research over the past decade, this paper examines local definitions of ‘middleness’ and the moralized meanings ascribed to it. Whilst being ‘in the middle’ is a source of pride and pleasure, connoting both achievement and enhanced self-control, it is simultaneously a source of great tension, bringing anxiety over the critical and damaging scrutiny of onlookers. For each positive aspect of a middle-class identity that emphasizes security and stability, there is a negative ramification or consequence that highlights the precariousness and potential instability of middle-class life. In exploring each of these aspects, I pay attention to the explicitly performative features of class identities. I conclude by considering the epistemological and experiential insights we gain into the construction of emergent class categories by focusing on self-ascribed identities and their performance.
Do shared etiological factors contribute to the relationship between sexual orientation and depression?
Authors: Zietsch B. P. , Verweij K. J. H. , Heath A. C. , Madden P. A. F. , Martin N. G. , Nelson E. C. , Lynskey M. T.
Published: August 2011

Background

Gays, lesbians and bisexuals (i.e. non-heterosexuals) have been found to be at much greater risk for many psychiatric symptoms and disorders, including depression. This may be due in part to prejudice and discrimination experienced by non-heterosexuals, but studies controlling for minority stress, or performed in very socially liberal countries, suggest that other mechanisms must also play a role. Here we test the viability of common cause (shared genetic or environmental etiology) explanations of elevated depression rates in non-heterosexuals.

Method

A community-based sample of adult twins (n=9884 individuals) completed surveys investigating the genetics of psychiatric disorder, and were also asked about their sexual orientation. Large subsets of the sample were asked about adverse childhood experiences such as sexual abuse, physical abuse and risky family environment, and also about number of older brothers, paternal and maternal age, and number of close friends. Data were analyzed using the classical twin design.

Results

Non-heterosexual males and females had higher rates of lifetime depression than their heterosexual counterparts. Genetic factors accounted for 31% and 44% of variation in sexual orientation and depression respectively. Bivariate analysis revealed that genetic factors accounted for a majority (60%) of the correlation between sexual orientation and depression. In addition, childhood sexual abuse and risky family environment were significant predictors of both sexual orientation and depression, further contributing to their correlation.

Conclusions

Non-heterosexual men and women had elevated rates of lifetime depression, partly due to shared etiological factors, although causality cannot be definitively resolved.
‘The Taste Buddies’: participation and empowerment in a residential home for older people
Authors: BAUR VIVIANNE , ABMA TINEKE
Published: August 2011

The active participation and autonomy of older people living in residential homes is considered to be problematic. However, in our action research project conducted in a Dutch residential care organisation we found ways to enhance residents' direct participation. This form of participation is grounded in deliberative and participatory approaches to democracy. In this article we describe how a group of seven residents (all female), calling themselves ‘The Taste Buddies’, developed a joint vision on how meals could be improved. The facilitation of this process enhanced this group's empowerment, building interpersonal trust, social identity and joint purpose. We will take the reader through this process and discuss the developments of these older women against the background of relational empowerment. We argue that resident participation as partnership with employees and managers starts with relational empowerment among residents themselves (enclave deliberation). This process is non-linear and requires time and constructive facilitation.
Research into practice: Vocabulary
Authors: Nation I. S. P.
Published: August 2011

Editorial note

This new strand in the journal provides a space for contributors to present a personal stance either on future research needs or on the perceived current applications of research in the classroom. Like much of our current content, it echoes the historical uniqueness of this journal in terms of its rich and expert overview of recent research in the field of L2 teaching and learning. However, this new strand takes such research as its starting point and attempts to look forward, using these findings both to debate their application in the language learning classroom and also to suggest where research would be best directed in the future. Thus, the objective of both types of paper is eminently practical: contributors to the research agenda will present suggestions for what research might usefully be undertaken, given what is currently known or what is perceived to be necessary. In the research into practice papers there will be critical appraisal both of what research is, and is not, getting through to the language learning classroom, policy making, curriculum design, evaluation of teaching and/or assessment programmes, and practical suggestions made for improving such outcomes.

This article is a personal view of the application of research on vocabulary to teaching and how there are three different types or categories of relationship between that research and the teaching to which it is applied: first, where the research is not applied or not applied well, second, where it is reasonably well applied, and third, where it is over-applied. For each of these three categories, I look at what I consider to be the most important areas of research and suggest why they fit into that category. The topics covered include planning vocabulary courses, distinguishing high frequency and low frequency words, extensive reading, the deliberate learning of vocabulary, academic vocabulary and vocabulary teaching.
The cultural dimensions of language teaching and learning
Authors: Risager Karen
Published: August 2011

Language teaching and learning has many different cultural dimensions, and over the years more and more of these have been the subject of research. The first dimension to be explored was that of content: the images of target language countries and the world that were offered in textbooks and presented in class. The next dimension was that of the learner: the (inter)cultural learning, competence and identity of the learner or subject. The next dimension was context: the situation and role of language teaching and learning in society and in the world.
Review of recent research (2000–2010) on learning and instruction with specific reference to L2 Japanese
Authors: Mori Yoshiko , Mori Junko
Published: August 2011

This review aims to identify major issues in and the direction of recent L2 Japanese research by reviewing over 200 empirical studies published in English or Japanese between 2000 and 2010. The first part of this article examines topics in second language acquisition (SLA) research with regard to L2 Japanese, including vocabulary andkanji(Chinese characters transferred into Japanese) learning, syntactic development, reading and writing in L2 Japanese, interlanguage pragmatics and language socialization, affective factors, and multilingualism and the acquisition of Japanese as a heritage language. The second part offers an overview of issues and problems in pedagogical practices, including curriculum design, culture in language education, classroom discourse, and study abroad. The review of these themes illustrates a broad picture of current research in L2 Japanese learning and instruction inspired by general trends in SLA and applied linguistics research, as well as unique features of Japanese language and social contexts.
Identity, language learning, and social change
Authors: Norton Bonny , Toohey Kelleen
Published: August 2011

In this review article on identity, language learning, and social change, we argue that contemporary poststructuralist theories of language, identity, and power offer new perspectives on language learning and teaching, and have been of considerable interest in our field. We first review poststructuralist theories of language, subjectivity, and positioning and explain sociocultural theories of language learning. We then discuss constructs ofinvestmentandimagined communities/imagined identities(Norton Peirce 1995; Norton 1997, 2000, 2001), showing how these have been used by diverse identity researchers. Illustrative examples of studies that investigate how identity categories like race, gender, and sexuality interact with language learning are discussed. Common qualitative research methods used in studies of identity and language learning are presented, and we review the research on identity and language teaching in different regions of the world. We examine how digital technologies may be affecting language learners' identities, and how learner resistance impacts language learning. Recent critiques of research on identity and language learning are explored, and we consider directions for research in an era of increasing globalization. We anticipate that the identities and investments of language learners, as well as their teachers, will continue to generate exciting and innovative research in the future.
Exploring identity in SLA: A dialogue about methodologies
Authors: Tremmel Betsy , De Costa Peter I.
Published: August 2011

A panel discussion presented at the Second Language Acquisition Graduate Student Symposium on 17 April 2010 at the University of Wisconsin-Madison.
Research in the Doctoral Program in Second Language Acquisition at the University of Wisconsin-Madison
Authors: De Costa Peter I. , Bernales Carolina , Merrill Margaret
Published: August 2011

Faculty and graduate students in the Doctoral Program in Second Language Acquisition (SLA) at the University of Wisconsin-Madison engage in a broad spectrum of research. From Professor Sally Magnan's research on study abroad and Professor Monika Chavez's work in foreign language policy through Professor Richard Young's examination of language-in-interaction, Professor Jane Zuengler's investigation of language socialization, Professor Diana Frantzen's research in second language (L2) vocabulary acquisition and linguistic analysis of literature, to Professor Catherine Stafford's investigation of processes involved in Spanish-English bilinguals’ acquisition of a third language (L3), our research interests encompass much of the SLA field.
Supplementation with the histone deacetylase inhibitor trichostatin A during in vitro culture of bovine embryos
Authors: Oliveira Clara Slade , Saraiva Naiara Zoccal , de Souza Marcela Maria , de Almeida Drummond Tetzner Tatiane , de Lima Marina Ragagnin , Garcia Joaquim Mansano
Published: August 2011

Trichostatin A (TSA) is a histone deacetylase inhibitor that induces histone hyperacetylation and increases gene expression levels. The aim of the present study was to establish a suitable condition for the use of TSA in in vitro cultures of bovine embryos, and to determine whether TSA would increase blastocyst rates by improvement of chromatin remodelling during embryonic genome activation and by increasing the expression of crucial genes during early development. To test this hypothesis, 8-cell embryos were exposed to four concentrations of TSA for different periods of time to establish adequate protocols. In a second experiment, three experimental groups were selected for the evaluation of embryo quality based on the following parameters: apoptosis, total cell number and blastocyst hatching. TSA promoted embryonic arrest and degeneration at concentrations of 15, 25 and 50 nM. All treated groups presented lower blastocyst rates. Exposure of embryos to 5 nM for 144 h and to 15 nM for 48 h decreased blastocyst hatching. However, the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay (TUNEL) assay revealed similar apoptosis rates and total cell numbers in all groups studied. Although, in the present study, TSA treatment did not improve the parameters studied, the results provided background information on TSA supplementation during in vitro culture of bovine embryos and showed that embryo quality was apparently not affected, despite a decrease in blastocyst rate after exposure to TSA.
Effect of cryoprotectants on the survival of cascudo preto (Rhinelepis aspera) embryos stored at –8°C
Authors: Fornari Darci Carlos , Ribeiro Ricardo Pereira , Streit Danilo , Godoy Leandro Cesar , Neves Patrícia Ribeiro , de Oliveira Diego , Sirol Rodolfo Nardez
Published: August 2011

Cryopreservation of germplasm provides a promising method to preserve fish genetic material, which is of great importance in preservation of species diversity, aquaculture, and management of fish models used in biomedical research. In the present study, cryopreservation of Rhinelepis aspera embryos, a Brazilian endangered species, was studied for the first time using a short-term cooling protocol. Embryos at blastoporous closing stage were selected, placed in 6-ml glass vials and stored at −8°C for 6 h in 10 different cryoprotectant solutions: S1 (17.1% sucrose + 9% methanol); S2 (17.1% sucrose + 9% DMSO); S3 (8.5% sucrose + 8.5% glucose + 9% methanol); S4 (8.5% sucrose + 8.5% glucose + 9% DMSO); S5 (17.1% sucrose + 9% ethylene glycol); S6 (8.5% sucrose + 8.5% glucose + 9% ethylene glycol); S7 (17.1% sucrose + 4.5% methanol + 4.5% DMSO); S8 (17.1% sucrose + 4.5% methanol + 4.5% ethylene glycol); S9 (17.1% sucrose + 4.5% DMSO + 4.5% ethylene glycol); and S10 (100% water). Embryo viability was assessed by hatching rate, counting live larvae and number of failed eggs under a stereomicroscope. The results showed that only the cryoprotectant solutions that contained methanol associated to sucrose (S1, S7 and S8) provided partial protection of Rhinelepis aspera embryos from cold damage (over 50% hatching rate in S1), while the use of DMSO and ethylene glycol, isolated or in combination, resulted in no hatching rate. Further studies are needed in order to extend the storage time and to improve the hatching rate for the species.
Artificial oocyte activation and human failed-matured oocyte vitrification followed byin vitromaturation
Authors: Liu Y. , Cao Y.X. , Zhang Z.G. , Xing Q.
Published: August 2011

The investigation presented in this paper was conducted on the effect of oocytes activation on frozen–thawed human immature oocytes followed byin vitromaturation (IVM). A total of 386 failed-matured oocytes (germinal vesicle (GV) and metaphase I (MI) stages) was randomly divided into two groups: fresh group and vitrification group, GV group and MI group, respectively). The matured oocytes were subject to intracytoplasmic sperm injection (ICSI) after IVM had been carried out. The vitrification group was randomly divided into two groups: controlled and artificial oocyte activation (AOA). The injected oocytes in the controlled group were cultured in cleavage medium. The AOA group oocytes were activated by exposing them to 7% anhydrous alcohol for 6 min then cultured in cleavage medium as well. The rates of fertilization and early embryonic development were compared between the controlled and AOA groups. In MI vitrification group, the high-quality embryo formation rate and blastocyst formation rate were significantly higher in the AOA group than in the controlled group (P< 0.01). In the GV vitrification group, the high-quality embryo formation rate was significantly higher in the AOA group than in the controlled group (P< 0.05). These results indicate that AOA may be good for early embryonic development of vitrified immature human oocytes.
Insights into the genetics of osteoporosis from recent genome-wide association studies
Authors: Zheng Hou-Feng , Spector Timothy D. , Richards J. Brent
Published: August 2011

Osteoporosis, which is characterised by reduced bone mineral density (BMD) and an increased risk of fragility fractures, is the result of a complex interaction between environmental factors and genetic variants that confer susceptibility. Heritability studies have shown that BMD and other osteoporosis-related traits such as ultrasound properties of bone, skeletal geometry and bone turnover have significant inheritable components. Although previous linkage and candidate gene studies have provided few replicated loci for osteoporosis, genome-wide association approaches have produced clear and reproducible findings. To date, 20 genome-wide association studies (GWASs) for osteoporosis and related traits have been conducted, identifying dozens of genes. Further meta-analyses of GWAS data and deep resequencing of rare variants will uncover more novel susceptibility loci and ultimately provide possible therapeutic targets for fracture prevention.
Origin of solar magnetism
Authors: Choudhuri Arnab Rai
Published: August 2011

The most promising model for explaining the origin of solar magnetism is the flux transport dynamo model, in which the toroidal field is produced by differential rotation in the tachocline, the poloidal field is produced by the Babcock–Leighton mechanism at the solar surface and the meridional circulation plays a crucial role. After discussing how this model explains the regular periodic features of the solar cycle, we come to the questions of what causes irregularities of solar cycles and whether we can predict future cycles. Only if the diffusivity within the convection zone is sufficiently high, the polar field at the sunspot minimum is correlated with strength of the next cycle. This is in conformity with the limited available observational data.
Diagnostics for spectropolarimetry and magnetography
Authors: del Toro Iniesta Jose Carlos , Pillet Valentín Martínez
Published: August 2011

An assessment on the capabilities of modern spectropolarimeters and magnetographs is in order since most of our astrophysical results rely upon the accuracy of the instrumentation and on the sensitivity of the observables to variations of the sought physical parameters. A contribution to such an assessment will be presented in this talk where emphasis will be made on the use of the so-called response functions to gauge the probing capabilities of spectral lines and on an analytical approach to estimate the uncertainties in the results in terms of instrumental effects. The Imaging Magnetograph eXperiment (IMaX) and the Polarimetric and Helioseismic Imager (PHI) will be used as study cases.
The evolution of stellar surface activity and possible effects on exoplanets
Authors: Giampapa Mark S.
Published: August 2011

The evolution of stellar activity involves a complex interplay between the interior dynamo mechanism, the emergent magnetic field configurations and their coupling with stellar winds, the subsequent angular momentum evolution, and fundamental stellar parameters. The discussion of the evolution of surface activity will emphasize the main sequence phase, from the ZAMS to stars of solar-age. We will focus particularly on the evolution of the fractional area coverages of spots on the surfaces of solar-type stars. We fit an empirical relation to the fractional mean spot area coverage as a function of age for ages greater than the Pleiades of the form log(MeanSpotCoverage) = 0.90(±0.26) − 1.03(±0.10)log(Age), where Age is in Myr. In addition, we summarize the relative evolution of radiative emissions in various short wavelength bands that are associated with stellar magnetic field-related activity. Possible effects on young planetary atmospheres also are appropriate to consider given that stellar surface activity is the origin of the high-energy component of the ambient radiation and particle fields in which planetary atmosphere evolution occurs.
Time series photometry and starspot properties
Authors: Oláh Katalin
Published: August 2011

Systematic efforts of monitoring starspots from the middle of the XXth century, and the results obtained from the datasets, are summarized with special focus on the observations made by automated telescopes. Multicolour photometry shows correlations between colour indices and brightness, indicating spotted regions with different average temperatures originating from spots and faculae. Long-term monitoring of spotted stars reveals variability on different timescales.

On the rotational timescale new spot appearances and starspot proper motions are followed from continuous changes of light curves during subsequent rotations. Sudden interchange of the more and less active hemispheres on the stellar surfaces is the so called flip-flop phenomenon. The existence and strength of the differential rotation is seen from the rotational signals of spots being at different stellar latitudes.

Long datasets, with only short, annual interruptions, shed light on the nature of stellar activity cycles and multiple cycles. The systematic and/or random changes of the spot cycle lengths are discovered and described using various time-frequency analysis tools. Positions and sizes of spotted regions on stellar surfaces are calculated from photometric data by various softwares. From spot positions derived for decades, active longitudes on the stellar surfaces are found, which, in case of synchronized eclipsing binaries can be well positioned in the orbital frame, with respect to, and affected by, the companion stars.
Exploring the deep convection and magnetism of A-type stars
Authors: Featherstone Nicholas A. , Browning Matthew K. , Brun Allan Sacha , Toomre Juri
Published: August 2011

A-type stars have both a near-surface layer of fast convection that can excite acoustic modes and a deep zone of core convection whose properties may be probed with asteroseismology. Many A-type stars also exhibit large magnetic spots that are often attributed to surviving primordial fields of global scale in the intervening radiative zone. We have explored the potential for core convection in rotating A-type stars to build strong magnetic fields through dynamo action. These 3-D simulations using the ASH code provide guidance on the nature of differential rotation and magnetic fields that may be present in the deep interiors of these stars, thus informing the asteroseismic deductions now becoming feasible. Our models encompass the inner 30% by radius of a two solar mass A-type star, rotating at four times the solar rate and capturing the convective core and a portion of the overlying radiative envelope. Convection in these stars drives a strong retrograde differential rotation and yields a core that is prolate in shape. When dynamo action is admitted, the convection generates strong magnetic fields largely in equipartition with the dynamics. Remarkably, introducing a modest but large-scale external field threading the radiative envelope (which may be of primordial origin) can substantially alter the turbulent dynamics of the convective interior. The resulting convection involves a complex assembly of helical rolls that link distant portions of the core and stretch and advect magnetic field, ultimately yielding magnetic fields of super-equipartition strength.
Chemical spots and their dynamical evolution on HgMn stars
Authors: Korhonen Heidi , Hubrig Swetlana , Briquet Maryline , González Federico , Savanov Igor
Published: August 2011

Our recent studies of late B-type stars with HgMn peculiarity revealed for the first time the presence of fast dynamical evolution of chemical spots on their surfaces. These observations suggest a hitherto unknown physical process operating in the stars with radiative outer envelopes. Furthermore, we have also discovered existence of magnetic fields on these stars that have up to now been thought to be non-magnetic. Here we will discuss the dynamical spot evolution on HD 11753 and our new results on magnetic fields on AR Aur.
Differential rotation on the young solar analogue V889 Herculis
Authors: Kővári Zsolt , Frasca Antonio , Biazzo Katia , Vida Krisztián , Marilli Ettore , Çakırlı Ömür
Published: August 2011

V889 Herculis is one of the brightest single early-G type stars, a young Sun, that is rotating fast enough (Prot =1.337 days) for mapping its surface by Doppler Imaging. The 10 FOCES spectra collected between 13-16 Aug 2006 at Calar Alto Observatory allowed us to reconstruct one single Doppler image for two mapping lines. The Fe i-6411 and Ca i-6439 maps, in a good agreement, revealed an asymmetric polar cap and several weaker features at lower latitudes. Applying the sheared-image method with our Doppler reconstruction we perform an investigation to detect surface differential rotation (DR). The resulting DR parameter, δΩ/Ω≈0.009 of solar type, is compared to previous studies which reported either much stronger shear or comparably weak DR, or just preferred rigid rotation. Theoretical aspects are also considered and discussed.
The formation of a penumbra as observed with the German VTT and SoHO/MDI
Authors: Schlichenmaier Rolf , González Nazaret Bello , Rezaei Reza
Published: August 2011

The generation of magnetic flux in the solar interior and its transport to the outer solar atmosphere will be in the focus of solar physics research for the next decades. One key-ingredient is the process of magnetic flux emergence into the solar photosphere, and the reorganization to form the magnetic phenomena of active regions like sunspots and pores.

On July 4, 2009, we observed a region of emerging magnetic flux, in which a proto-spot without penumbra forms a penumbra within some 4.5 hours. This process is documented by multi-wavelength observations at the German VTT: (a) imaging, (b) data with high resolution and temporal cadence acquired in Fe I 617.3 nm with the 2D imaging spectropolarimter GFPI, and (c) scans with the slit based spectropolarimeter TIP in Fe I 1089.6 nm. MDI contiuum maps and magnetograms are used to follow the formation of the proto-spot, and the subsequent evolution of the entire active region.

During the formation of the penumbra, the area and the magnetic flux of the spot increases. The additional magnetic flux is supplied by the adjacent region of emerging magnetic flux: As emerging bipole separate, the poles of the spot polarity migrate towards the spot, and finally merge with it. As more and more flux is accumulated, a penumbra forms. From inversions we infer maps for the magnetic field and the Doppler velocity (being constant along the line-of-sight). We calculate the magnetic flux of the forming spot and of the bipole footpoints that merge with the proto-spot. We witness the onset of the Evershed flow and the associated enhance of the field inclination as individual penumbral filaments form. Prior to the formation of individual penumbral sectors we detect the existence of ‘counter’ Evershed flows. These in-flows turn into the classical radial Evershed outflows as stable penumbra segments form.
Global MHD phenomena and their importance for stellar surfaces
Authors: Arlt Rainer
Published: August 2011

This review is an attempt to elucidate MHD phenomena relevant for stellar magnetic fields. The full MHD treatment of a star is a problem which is numerically too demanding. Mean-field dynamo models use an approximation of the dynamo action from the small-scale motions and deliver global magnetic modes which can be cyclic, stationary, axisymmetric, and non-axisymmetric. Due to the lack of a momentum equation, MHD instabilities are not visible in this picture. However, magnetic instabilities must set in as a result of growing magnetic fields and/or buoyancy. Instabilities deliver new timescales, saturation limits and topologies to the system probably providing a key to the complex activity features observed on stars.
Solar subsurface flows of active regions: flux emergence and flare activity
Authors: Komm Rudolf , Howe Rachel , Hill Frank , Jain Kiran
Published: August 2011

We study the temporal variation of subsurface flows associated with active regions within 16 Mm of the solar surface. We have analyzed the subsurface flows of nearly 1000 active and quiet regions applying ring-diagram analysis to Global Oscillation Network Group (GONG) Dopplergram data. We find that newly emerging active regions are characterized by enhanced upflows and fast zonal flows in the near-surface layers, as expected for a flux tube rising from deeper layers of the convection zone. The subsurface flows associated with strong active regions are highly twisted, as indicated by their large vorticity and helicity values. The dipolar pattern exhibited by the zonal and meridional vorticity component leads to the interpretation that these subsurface flows resemble vortex rings, when measured on the spatial scales of the standard ring-diagram analysis.
Nature of the unusually long solar cycles
Authors: Zolotova Nadezhda , Ponyavin Dmitri
Published: August 2011

The evolution of prolonged and unusually long solar cycles such as 23rd, 20th, and especially 4th is considered. Why the length of the 4th cycle was exceptionally large or really composed of two short cycles? Are the prolonged solar minima can be considered as precursor of low activity of the next cycles? Resolving these puzzles seems to be very important for dynamo theories trying to explain the solar long-term variations. We propose a possible model of the butterfly diagram during unusually long and prolonged cycles, based on (i) the Gnevyshev idea of sunspot distribution over the latitudes, and (ii) the phase differences of the northern and southern hemispheric activities.
Spots on Betelgeuse, what are they?
Authors: Dupree Andrea K.
Published: August 2011

The supergiant star Alpha Orionis (Betelgeuse) is the only star other than the Sun to be spatially resolved either through direct imaging or through reconstruction of interferometric observations. Centimeter-radio wavelength, infrared and ultraviolet images reveal a few bright hot spots in the photosphere and chromosphere that possess characteristics different from sunspots. Large photospheric spots on Betelgeuse appear to result from convective motions, consistent with radiative hydrodynamic modeling; the chromospheric hot spots may be produced by shock waves in the chromosphere excited by the convective motions or pulsation in the photosphere. Bright chromospheric spots that cluster around the pole of Betelgeuse could be a natural result of shock breakout in a rotating star.
Velocity fields in and around sunspots at the highest resolution
Authors: Denker Carsten , Verma Meetu
Published: August 2011

The flows in and around sunspots are rich in detail. Starting with the Evershed flow along low-lying flow channels, which are cospatial with the horizontal penumbral magnetic fields, Evershed clouds may continue this motion at the periphery of the sunspot as moving magnetic features in the sunspot moat. Besides these well-ordered flows, peculiar motions are found in complex sunspots, where they contribute to the build-up or relaxation of magnetic shear. In principle, the three-dimensional structure of these velocity fields can be captured. The line-of-sight component of the velocity vector is accessible with spectroscopic measurements, whereas local correlation or feature tracking techniques provide the means to assess horizontal proper motions. The next generation of ground-based solar telescopes will provide spectropolarimetric data resolving solar fine structure with sizes below 50 km. Thus, these new telescopes with advanced post-focus instruments act as a ‘zoom lens’ to study the intricate surface flows associated with sunspots. Accompanied by ‘wide-angle’ observations from space, we have now the opportunity to describe sunspots as a system. This review reports recent findings related to flows in and around sunpots and highlights the role of advanced instrumentation in the discovery process.
In-depth survey of sunspot and active region catalogs
Authors: Lefèvre Laure , Clette Frédéric , Baranyi Tunde
Published: August 2011

When consulting detailed photospheric catalogs for solar activity studies spanning long time intervals, solar physicists face multiple limitations in the existing catalogs: finite or fragmented time coverage, limited time overlap between catalogs and even more importantly, a mismatch in contents and conventions. In view of a study of new sunspot-based activity indices, we have conducted a comprehensive survey of existing catalogs.

In a first approach, we illustrate how the information from parallel catalogs can be merged to form a much more comprehensive record of sunspot groups. For this, we use the unique Debrecen Photoheliographic Data (DPD), which is already a composite of several ground observatories and SOHO data, and the USAF/Mount Wilson catalog from the Solar Optical Observing Network (SOON). We also describe our semi-interactive cross-identification method, which was needed to match the non-overlapping solar active region nomenclature, the most critical and subtle step when working with multiple catalogs. This effort, focused here first on the last two solar cycles, should lead to a better central database collecting all available sunspot group parameters to address future solar cycle studies beyond the traditional sunspot index time series Ri.
The Sun at high resolution: first results from the Sunrise mission
Authors: Solanki S. K. , Barthol P. , Danilovic S. , Feller A. , Gandorfer A. , Hirzberger J. , Lagg A. , Riethmüller T. L. , Schüssler M. , Wiegelmann T. , Bonet J. A. , Pillet V. Martínez , Khomenko E. , del Toro Iniesta J. C. , Domingo V. , Palacios J. , Knölker M. , González N. Bello , Borrero J. M. , Berkefeld T. , Franz M. , Roth M. , Schmidt W. , Steiner O. , Title A. M.
Published: August 2011

The Sunrise balloon-borne solar observatory consists of a 1m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system and further infrastructure. The first science flight of Sunrise yielded high-quality data that reveal the structure, dynamics and evolution of solar convection, oscillations and magnetic fields at a resolution of around 100 km in the quiet Sun. Here we describe very briefly the mission and the first results obtained from the Sunrise data, which include a number of discoveries.
Modelling stellar coronal magnetic fields
Authors: Jardine Moira , Donati Jean-Francois , Arzoumanian Doris , de Vidotto Aline
Published: August 2011

Our understanding of the structure and dynamics of stellar coronae has changed dramatically with the availability of surface maps of both star spots and also magnetic field vectors. Magnetic field extrapolations from these surface maps reveal surprising coronal structures for stars whose masses and hence internal structures and dynamo modes may be very different from that of the Sun. Crucial factors are the fraction of open magnetic flux (which determines the spin-down rate for the star as it ages) and the location and plasma density of closed-field regions, which determine the X-ray and radio emission properties. There has been recent progress in modelling stellar coronae, in particular the relative contributions of the field detected in the bright surface regions and the field that may be hidden in the dark star spots. For the Sun, the relationship between the field in the spots and the large scale field is well studied over the solar cycle. It appears, however, that other stars can show a very different relationship.
The spots on Ap stars
Authors: Kochukhov Oleg
Published: August 2011

The upper main sequence magnetic chemically peculiar (Ap) stars exhibit a non-uniform distribution of chemical elements across their surfaces and with height in their atmospheres. These inhomogeneities, responsible for the conspicuous photometric and spectroscopic variation of Ap stars, are believed to be produced by atomic diffusion operating in the stellar atmospheres stabilized by multi-kG magnetic fields. Here I present an overview of the current state-of-the-art in understanding Ap-star spots and their relation to magnetic fields. In particular, I highlight recent 3-D chemical spot structure studies and summarize magnetic field mapping results based on the inversion of the full Stokes vector spectropolarimetric observations. I also discuss a puzzling new type of spotted stars, HgMn stars, in which the formation and evolution of heavy element spots is driven by a poorly understood mechanism, apparently unrelated to magnetic fields.
Disentangling between stellar activity and planetary signals
Authors: Boisse Isabelle , Bouchy François , Hébrard Guillaume , Bonfils Xavier , Santos Nuno , Vauclair Sylvie
Published: August 2011

Photospheric stellar activity (i.e. dark spots or bright plages) might be an important source of noise and confusion in the radial-velocity (RV) measurements. Radial-velocimetry planet search surveys as well as follow-up of photometric transit surveys require a deeper understanding and characterization of the effects of stellar activities to disentangle it from planetary signals.

We simulate dark spots on a rotating stellar photosphere. The variations of the RV are characterized and analyzed according to the stellar inclination, the latitude and the number of spots. The Lomb-Scargle periodograms of the RV variations induced by activity present power at the rotational period Prot of the star and its two-first harmonics Prot/2 and Prot/3. Three adjusted sinusoids fixed at the fundamental period and its two-first harmonics allow to remove about 90% of the RV jitter amplitude. We apply and validate our approach on four known active planet-host stars: HD 189733, GJ 674, CoRoT-7 and ι Hor. We succeed in fitting simultaneously activity and planetary signals on GJ674 and CoRoT-7. We excluded short-period low-mass exoplanets around ι Hor. Our approach is efficient to disentangle reflex-motion due to a planetary companion and stellar-activity induced-RV variations provided that 1) the planetary orbital period is not close to that of the stellar rotation or one of its two-first harmonics, 2) the rotational period of the star is accurately known, 3) the data cover more than one stellar rotational period.
The structure and evolution of global solar magnetic fields
Authors: Mackay Duncan H.
Published: August 2011

This review will discuss both observational and theoretical aspects of the Sun's global magnetic field. First recent observations will be described, along with the main physical processes leading to the time evolution and structure of the global field. Following this, recent theoretical models of both the global surface and coronal magnetic field will be presented. The application of these models to the structure of the corona, formation of solar filaments, the onset of CMEs and finally the origin and variation of the Sun's open flux will be discussed.