bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in visitor perceptions of a polar bear enclosure based on the presence of natural vs. un‐natural enrichment items
Authors: Kutska Debra
Published: December 2008

A debate exists among modern zoo staff as to whether or not the addition of un‐naturalistic enrichment takes away from, or even defeats, the educational messages designers are trying to incorporate in naturalistic exhibits. A visitor study was conducted at the Central Park Zoo's polar bear exhibit in order to determine whether or not the type of enrichment in an enclosure actually alters guest perceptions. Visitors were exposed to one of two enrichment treatments in the bear enclosure: Naturalistic or Un‐naturalistic. The results of this study suggest that enrichment type did not alter the perceptions of visitors. However, it did identify some of the different ways adults and youths perceive animals and zoos. Additionally, the study highlighted the varying perceptions individuals have of the concept of polar bears vs. their perceptions of the captive individuals at the Central Park Zoo. Implications for enrichment usage and exhibit design are discussed. Zoo Biol 28:292–306, 2009. © 2008 Wiley‐Liss, Inc.
Unexpectedly high field-effect mobility of a soluble, low molecular weight oligoquaterthiophene fraction with low polydispersity
Authors: Pingel Patrick , Zen Achmad , Neher Dieter , Lieberwirth Ingo , Wegner Gerhard , Allard Sybille , Scherf Ullrich
Published: December 2008

Layers made from soluble low molecular weight polythiophene PQT-12 with low polydispersity exhibit a highly ordered structure and charge-carrier mobilities of the order of 10−3 cm2/(V s), which we attribute to its proximity to monodispersity. We propose that polydispersity is a decisive factor with regard to structure formation and transport properties of soluble low molecular weight polythiophenes.
Alpha, Dimension-Free, and Model-Based Internal Consistency Reliability
Authors: Bentler Peter M.
Published: December 2008

As pointed out by Sijtsma (in press), coefficient alpha is inappropriate as a single summary of the internal consistency of a composite score. Better estimators of internal consistency are available. In addition to those mentioned by Sijtsma, an old dimension-free coefficient and structural equation model based coefficients are proposed to improve the routine reporting of psychometric internal consistency. The various ways to measure internal consistency are also shown to be appropriate to binary and polytomous items.
Coefficients Alpha, Beta, Omega, and the glb: Comments on Sijtsma
Authors: Revelle William , Zinbarg Richard E.
Published: December 2008

There are three fundamental problems in Sijtsma (Psychometrika, 2008): (1) contrary to the name, the glb is not the greatest lower bound of reliability but rather is systematically less than ωt (McDonald, Test theory: A unified treatment, Erlbaum, Hillsdale, 1999), (2) we agree with Sijtsma that when considering how well a test measures one concept, α is not appropriate, but recommend ωt rather than the glb, and (3) the end user needs procedures that are readily available in open source software.
Formulating Alcohol‐Free Microemulsions Using Rhamnolipid Biosurfactant and Rhamnolipid Mixtures
Authors: Nguyen Thu T. , Sabatini David A.
Published: December 2008

This research focused on developing alcohol‐free biosurfactant‐based microemulsions. Rhamnolipid‐based mixtures were found to have double the solubilization parameter as compared to sodium bis(2‐ethyl) dihexyl sulfosuccinate/sodium dihexyl sulfosuccinate/sodium mono‐ and dimethyl naphthalene sulfonate at the same total molar concentration. For the first time, a phase diagram was developed for surfactant mixtures containing soy methyl ester ethoxylate, rhamnolipid and oleyl alcohol with limonene oil. This phase diagram can be used as a guideline for selecting a surfactant system and surfactant ratio to formulate microemulsions with a given oil. In addition, the alcohol‐free biosurfactant‐based microemulsions required reasonable salinity values for limonene, making it viable in a variety of applications.
Conservative versus surgical treatment of late-onset Legg-Calve-Perthes disease: A radiographic comparison at skeletal maturity
Authors: Arkader Alexandre , Sankar Wudbhav N. , Amorim Romildo Merçon
Published: December 2008

Background

Late-onset Legg-Calve-Perthes disease (LCPD; i.e., disease onset after 8 years) has been associated with a more aggressive course and poorer long-term outcomes. The optimal treatment method of LCPD is still controversial, especially in this late-onset patient population. The purpose of this study was to evaluate the radiographic outcomes at the end of skeletal maturity in a cohort of patients with late-onset LCPD, comparing the results between conservative and surgical treatment.

Methods

We performed a retrospective comparative study of all 371 patients with LCPD seen at a single institution during a 30-year period. Children younger than 9 years of age at disease onset, bilateral cases, and children that had not reached skeletal maturity at last follow-up were excluded. Clinical data was collected from chart review and radiographs were staged according to the Waldenstrom and Catterall classifications. Patients treated conservatively (adductor tenotomy, bracing and physical therapy, or physical therapy alone) were compared to those treated with more extensive surgery (varus femoral osteotomy or Chiari pelvic osteotomy [CPO]). Final radiographic outcomes were based on a modified Stulberg criteria.

Results

Forty-three patients with an average age of 10.8 years and a mean follow-up of 10 years were identified. Twenty-one children received conservative treatment (15 underwent adductor tenotomy, followed by abduction cast or brace and physical therapy; six had only physical therapy) and 22 underwent surgery (16 underwent femoral varus osteotomy and six had CPO). Based on the modified Stulberg criteria, there was no significant difference in radiographic outcome between the surgical and the conservative treatment groups, but there were twice as many patients with a poor result in the conservative group.

Conclusion

Late-onset LCPD presents with an extensive head involvement and shorter disease course. While there was no statistical difference between surgical and conservative treatment, there was a trend toward better radiographic outcomes when varus derotational osteotomy was performed early in the disease process.
The site for the allosteric activator GTP of Escherichia coli UMP kinase
Authors: Marco-Marín Clara , Rubio Vicente
Published: December 2008

UMP kinase (UMPK), a key bacterial pyrimidine nucleotide biosynthesis enzyme, is UTP‐inhibited and GTP‐activated. We delineate the GTP site of Escherichia coli UMPK by alanine mutagenesis of R92, H96, R103, W119 or R130, abolishing GTP activation; of S124 and R127, decreasing affinity for GTP; and of N111 and D115, with little detrimental effect. We exclude the correspondence with the modulatory ATP site of Bacillus anthracis UMPK, confirming the functionality of the GTP site found by Evrin. Mutants R92A, H96A and R127A are constitutively activated, suggesting key roles of these residues in allosteric signal transduction and of positive charge neutralization in triggering activation. No mutation hampered UTP inhibition, excluding overlapping of the UTP and GTP sites.
Platelet aggregation, eicosanoid production and thrombogenic ratio in individuals at high cardiovascular risk consuming meat enriched in walnut paste. A crossover, placebo-controlled study
Authors: Canales Amaia , Bastida Sara , Librelottto Josana , Nus Meritxell , Sánchez-Muniz Francisco J. , Benedi Juana
Published: December 2008

Walnut consumption produces beneficial cardiovascular effects. The aim of the present study is to compare the effects of meat enriched in walnut paste (WM) and low-fat meat (LM) consumptions on platelet aggregation, plasma thromboxane A2(TXA2, measured as TXB2), prostacyclin I2(PGI2, as 6-keto-PGF1α) and the thrombogenic ratio (TXB2/6-keto-PGF1α) in volunteers at high CVD risk. Twenty-two adults were placed on a random, non-blinded crossover study involving two test periods (five portions WM/week for 5 week; five portions LM/week for 5 week) separated by a 4- to 6-week washout period. The participants were asked to complete a diet record throughout the study. Platelet aggregation, plasma TXB2, 6-keto-PGF1αproduction and the TXB2/6-keto-PGF1α ratio were determined at baseline and at weeks 3 and 5 for the two dietary periods. The WM diet contains a lower SFA content, a higher concentration of PUFA and a more favourablen-6/n-3 ratio than the LM diet. Significant time × treatment interactions were observed for TXB2(P = 0·048) and the TXB2/6-keto-PGF1α ratio (P = 0·028). The WM diet significantly increased the level of 6-keto-PGF1α (P = 0·037) and decreased the TXB2/6-keto-PGF1α ratio (P = 0·048). At week 5, significant differences (P < 0·05) between treatments were found for maximum aggregation rate, TXB2values and the TXB2/6-keto-PGF1α ratio. The effects on TXB2and the TXB2/6-keto-PGF1α ratio were time-course dependent (P = 0·019 and 0·011, respectively). The WM and LM diets reduced TXB2levels most (P = 0·050) in obese individuals, while the TXB2/6-keto-PGF1α ratio decreased most (P = 0·066) in volunteers whose serum cholesterol levels were ≥ 2200 mg/l. The WM diet should be considered a functional meat because it improves the thrombogenic status mainly in individuals with high-cholesterol levels or high BMI.
STATIONARY SOLUTIONS TO FOREST KINEMATIC MODEL
Authors: CHUAN LE HUY , TSUJIKAWA TOHRU , YAGI ATSUSHI
Published: December 2008

We continue the study of a mathematical model for a forest ecosystem which has been presented by Y. A. Kuznetsov, M. Y. Antonovsky, V. N. Biktashev and A. Aponina (A cross-diffusion model of forest boundary dynamics, J. Math. Biol. 32 (1994), 219–232). In the preceding two papers (L. H. Chuan and A. Yagi, Dynamical systemfor forest kinematic model, Adv. Math. Sci. Appl. 16 (2006), 393–409; L. H. Chuan, T. Tsujikawa and A. Yagi, Aysmptotic behavior of solutions for forest kinematic model, Funkcial. Ekvac. 49 (2006), 427–449), the present authors already constructed a dynamical system and investigated asymptotic behaviour of trajectories of the dynamical system. This paper is then devoted to studying not only the structure (including stability and instability) of homogeneous stationary solutions but also the existence of inhomogeneous stationary solutions. Especially it shall be shown that in some cases, one can construct an infinite number of discontinuous stationary solutions.
COMB GRAPHS AND SPECTRAL DECIMATION
Authors: JORDAN JONATHAN
Published: December 2008

We investigate the spectral properties of matrices associated with comb graphs. We show that the adjacency matrices and adjacency matrix Laplacians of the sequences of graphs show a spectral similarity relationship in the sense of work by L. Malozemov and A. Teplyaev (Self-similarity, operators and dynamics,Math. Phys. Anal. Geometry6(2003), 201–218), and hence these sequences of graphs show a spectral decimation property similar to that of the Laplacians of the Sierpiński gasket graph and other fractal graphs.
A VARIANT ON THE NOTION OF A DIOPHANTINE s-TUPLE
Authors: BANKS WILLIAM D. , LUCA FLORIAN , SZALAY LÁSZLÓ
Published: December 2008

We show that there is an infinite set of natural numbers with the property that $1+\prod_{n\in\cR}n$ is square-free for every finite subset ⊆ .
THE DUALITY PROBLEM FOR THE CLASS OF ORDER WEAKLY COMPACT OPERATORS
Authors: AQZZOUZ BELMESNAOUI , HMICHANE JAWAD
Published: December 2008

We study the duality problem for order weakly compact operators by giving sufficient and necessary conditions under which the order weak compactness of an operator implies the order weak compactness of its adjoint and conversely.
ASYMPTOTIC BEHAVIOUR OF EIGENVALUES OF CERTAIN POSITIVE INTEGRAL OPERATORS
Authors: SOYKAN YÜKSEL
Published: December 2008

In this paper, we prove a theorem concerning asymptotic estimates of the eigenvalues of certain positive integral operators with Laplace transform type kernels.
THE ASYMPTOTIC ANALYSIS OF A CLASS OF SELF-ADJOINT SECOND-ORDER DIFFERENCE EQUATIONS: JORDAN BOX CASE
Authors: MOTYKA WOJCIECH
Published: December 2008

In this paper, we are computing asymptotic formulas for a base of solutions of the second-order difference equations in the double root case. Two methods are presented.
‘We are not blaming anyone, but if we don't know about amenities, we cannot seek them out’: black and minority older people's views on the quality of local health and personal social services in England
Authors: MANTHORPE JILL , ILIFFE STEVE , MORIARTY JO , CORNES MICHELLE , CLOUGH ROGER , BRIGHT LES , RAPAPORT JOAN ,   OPRSI
Published: December 2008

Improving access to culturally-appropriate services and enhancing responses to the needs of older people from black and minority ethnic backgrounds were among the aims of theNational Service Framework for Older People(NSFOP) that was introduced in England in 2001. Progress in meeting the aims of the NSFOP was evaluated by a mid-term independent review led by the Healthcare Commission, the body responsible for regulating health-care services in England. This paper reports the consultation with older people that underpinned the evaluation. It focuses on the views and experiences of older people from black and minority ethnic (BME) groups and of the staff that work in BME voluntary organisations. A rapid appraisal approach was used in 10 purposively selected local councils, and plural methods were used, including public listening events, nominal groups and individual interviews. In total 1,839 older people participated in the consultations and 1,280 (70%) completed a monitoring form. Some 30 per cent defined themselves as of a minority ethnic background. The concerns were more about the low recognition of culturally-specific and language needs than for the development of services exclusively for BME older people.
Some social consequences of remodelling English sheltered housing and care homes to ‘extra care’
Authors: WRIGHT FAY , TINKER ANTHEA , HANSON JULIENNE , WOJGANI HEDIEH , MAYAGOITIA RUTH
Published: December 2008

Across the United Kingdom, new build and remodelled ‘extra care’ schemes are being developed in many areas on the assumption that they offer older people with care needs an alternative to residential care. This paper reports an evaluation by a multi-disciplinary team of 10 extra-care schemes remodelled from sheltered housing or residential care units. The evaluation audited buildings and identified social and architectural problems. No two schemes in the sample were alike; some aimed for a dependency balance and others set a dependency threshold for admission. The three criteria used for assessing eligibility were the number of paid care hours the older person had at home, their property status and the type of disability. This article focuses on the wide variation in assessing eligibility for an extra-care place and on some social consequences of remodelling. A number of tenants remained in situ during the remodelling process in six of the schemes. Building professionals were unanimous that retaining some tenants on site caused significant development delays and increased the remodelling costs. There was also a social price to pay. ‘Old’ tenants resented their scheme changing into extra care and were hostile towards ‘new’ tenants who had obvious needs for support. In some extra-care schemes, ‘old’ tenants were refusing to participate in meals and all social activities.
‘I think I have had a good life’: the everyday lives of older women and men from a lifecourse perspective
Authors: GUNNARSSON EVY
Published: December 2008

Through increased longevity, older people today live for many years in retirement. Research on the everyday lives of older women and men who are not in need of help from elder care is scarce. This paper reports an in-depth study of a small sample of such relatively healthy older people in Sweden. The aim of the study was to describe, analyse and interpret from a lifecourse perspective how older women and men experience everyday life. Twenty informants were recruited through advertisements and they were interviewed twice. They were aged 75 to 90 years at the first interview. The informants belong to the cohort that was born before the Second World War and they have witnessed and benefitted from both unprecedented economic growth and the development of the Swedish welfare state. Both the men and the women had been in paid work outside the home, and once retired they were determined to remain active. Even though many had found that their capacities had reduced, the informants spontaneously stressed the importance of continuing to be physically and mentally active. They saw life as meaningful because they sustained links in different ways with kin, friends and organisations. They wanted to remain active as long as possible, even when a decline in health reduced the range of activities that they could pursue.
Juridical Bonds of Marriage for Jewish and Islamic Women
Authors: Madera Adelaide
Published: December 2008

This paper examines the condition of women in both Israel and Islamic countries, specifically their freedom to leave a marriage, and compares respective models. First, the study analyses the peculiar relationship between secular and religious law in Israel and Islamic countries. Second, it studies the nature of marriage as a contract in these legal systems, comparing a totally private approach and a mixed, public–private approach. Third, it analyses the possibilities of dissolution of marriage in such legal systems, indentifying some aspects of gender disparity. Finally it discusses some juridical tools offered in these legal contexts, which are intended to rebalance the exercise of a woman's freedom to leave a marital relationship and its conditions.
Recent Developments in Religious Liberty
Authors: Leigh Ian
Published: December 2008

This is the first in what is intended as a series of comments on current developments in the law concerning freedom of religion that will appear regularly in this Journal. This first survey deals with religious liberty challenges brought in the UK courts in 2007 and 2008. A subsequent survey will examine similar developments in international human rights law and especially before the European Court of Human Rights.
The Legal Challenges of Religious Polygamy in the USA
Authors: Witte John
Published: December 2008

A century and a half ago, Mormons made national headlines by claiming a First Amendment right to practise polygamy, despite criminal laws against it. In four cases, from 1879 to 1890, the United States Supreme Court firmly rejected their claim, and threatened to dissolve the Mormon church if they persisted. Part of the Court's argument was historical: the common law has always defined marriage as monogamous, and to change those rules ‘would be a return to barbarism’. Part of the argument was prudential: religious liberty can never become a licence to violate general criminal laws ‘lest chaos ensue’. And part of the argument was sociological: monogamous marriage ‘is the cornerstone of civilization’, and it cannot be moved without upending our whole culture. These old cases are still the law of the land and most Mormons renounced polygamy after 1890.
General Synod of the Church of England
Authors: Slack Stephen
Published: December 2008

In February, the Synod revised the draft legislation on clergy terms of service. Attention was chiefly focused on the parts of the draft Ecclesiastical Offices (Terms of Service) Measure dealing with the vesting of parsonage houses; in the event, the Synod voted to reject those provisions under which ownership of parsonage houses would have been transferred from the incumbent to the diocesan parsonages board. In contrast, the draft of the Regulations to be made under the Measure, which will specify the detailed terms of service, was accepted without amendment.
General Assembly of the Church of Scotland
Authors: MacLean Marjory A
Published: December 2008

The 2008 General Assembly of the Church of Scotland attended to various legal issues in the spirit of general reform.
General Synod of the Church of Ireland
Authors: Davey Michael
Published: December 2008

The Synod met in Galway; there were two Bills of particular significance.
The art of grocery shopping on a food stamp budget: factors influencing the food choices of low-income women as they try to make ends meet
Authors: Wiig Kristen , Smith Chery
Published: December 2008

Objective

Amidst a hunger–obesity paradox, the purpose of the present study was to examine the grocery shopping behaviour and food stamp usage of low-income women with children to identify factors influencing their food choices on a limited budget.

Design

Focus groups, which included questions based on Social Cognitive Theory constructs, examined food choice in the context of personal, behavioural and environmental factors. A quantitative grocery shopping activity required participants to prioritize food purchases from a 177-item list on a budget of $US 50 for a one-week period, an amount chosen based on the average household food stamp allotment in 2005.

Subjects

Ninety-two low-income women, with at least one child aged 9–13 years in their household, residing in the Twin Cities, Minnesota, USA.

Results

Participants' mean age was 37 years, and 76% were overweight or obese (BMI≥25·0kg/m2). Key findings suggest that their food choices and grocery shopping behaviour were shaped by not only individual and family preferences, but also their economic and environmental situation. Transportation and store accessibility were major determinants of shopping frequency, and they used various strategies to make their food dollars stretch (e.g. shopping based on prices, in-store specials). Generally, meat was the most important food group for purchase and consumption, according to both the qualitative and quantitative data.

Conclusions

Efforts to improve food budgeting skills, increase nutrition knowledge, and develop meal preparation strategies involving less meat and more fruits and vegetables, could be valuable in helping low-income families nutritionally make the best use of their food dollars.
The ‘Responsible’ Tenant and the Problem of Apathy
Authors: McKee Kim
Published: December 2008

In the last decade, the UK New Labour government has emphasised tenant participation in housing policy. Consequently, those individuals who decide to opt out of participation processes have been problematised as ‘apathetic’, and identified as needing to be ‘empowered’ through professional interventions. Drawing on research about community ownership in Glasgow, this paper argues that tenants' reasons for not getting involved are more than simply lack of interest. Tenants articulated an instrumental approach to participation, and rejected the conflation of tenant participation with tenant management. Practical barriers also obstructed their latent motivation.
Civil Society, Social Policy and Participatory Democracy: Past, Present and Future
Authors: Powell Fred
Published: December 2008

This article sets out to explore the relationship between civil society, social policy and participatory democracy, challenging the paternalistic and egoistic tradition of charity and the voluntary sector as its defining paradigm. Civil society is linked to the right to associate for social and political purposes. Radical and liberal traditions of civil society are compared and contrasted. It is suggested that historically participatory democracy can be viewed as a Social Left that embraces the politics of difference (recognition/respect) and equality (social justice/redistribution) through the mobilisation of the poor and excluded. The emphasis is on the activist citizen (new social movements) as opposed to the traditional active citizen (charity). It is concluded that this version of civil society potentially offers a new political and cultural grammar for the discourse of social policy – that is reflexive, inclusive and democratic.
Introduction: Resilience and Social Exclusion
Authors: Burchardt Tania , Huerta M. Carmen
Published: December 2008

Resilience and social exclusion are both slippery concepts. Attempting to explore the relationship between them – the challenge set for contributors to this themed section – might therefore be considered a rash undertaking. Nevertheless, there is much to be learned – theoretically, empirically and in terms of policy implications – from bringing together these two areas of investigation which have developed hitherto largely in isolation from each other.
Educational Outcomes: Adversity and Resilience
Authors: Cassen Robert , Feinstein Leon , Graham Philip
Published: December 2008

In the context of risk and resilience, the paper attempts to integrate three strands of research: genetic and mental-health factors, the findings of cohort studies and those of other investigations of educational outcomes. A very wide range of factors, many of them related to disadvantage, bear on such outcomes, but none deterministically. Intelligence, conduct and emotional disorders are all found to influence academic achievement to varying degrees, as do a number of aspects of family, school and the wider social environment. Aspects that contribute to resilience are identified, and the paper concludes with a discussion of interventions to enhance resilience.
More than ‘Just Coping’: The Antecedents and Dynamics of Resilience in a Qualitative Longitudinal Study
Authors: Davidson Rosemary
Published: December 2008

This paper attempts to contribute to understandings of the role of resilience as a process enabling individuals to steer a positive course in their lives by drawing on longitudinal qualitative data collected from six case study individuals, drawn from a wider study of one hundred families over a seven-year period. It is shown how respondents construct their own life trajectories, specifically reflecting on the changes and challenges they face. Additionally, this work offers a policy perspective to the debate on resilience, examining the interplay between recent government initiatives and their potential role in fostering resilience.
Conditionality in Public Policy Targeted to the Poor: Promoting Resilience?
Authors: Bastagli Francesca
Published: December 2008

This paper explores the role of conditionality in policies targeting the poor. By requiring beneficiaries to send their children to school and to undertake regular health visits, proponents argue, conditionalities improve human capital outcomes, promoting resilience. This widespread perception has led to the adoption of conditional cash transfers in many countries. Yet policy debate on conditionality does not always reflect a full appreciation of how behavioural, administrative and political economy variables influence outcomes. This paper identifies the multiple channels through which conditionality determines human capital outcomes and reviews the evidence on linkages between conditionality and processes of resilience.
Some Useful Sources
Authors: Mohaupt Sarah
Published: December 2008

The following list of sources presents a brief overview of resilience research, listing publications, research centres, projects and training programmes on resilience.
Nearly ordinary Galois deformations over arbitrary number fields
Authors: Calegari Frank , Mazur Barry
Published: December 2008

Let K be an arbitrary number field, and let ρ : Gal($\math{\bar{K}}$/K) → GL2(E) be a nearly ordinary irreducible geometric Galois representation. In this paper, we study the nearly ordinary deformations of ρ. When K is totally real and ρ is modular, results of Hida imply that the nearly ordinary deformation space associated to ρ contains a Zariski dense set of points corresponding to ‘automorphic’ Galois representations. We conjecture that if K is not totally real, then this is never the case, except in three exceptional cases, corresponding to: (1) ‘base change’, (2) ‘CM’ forms, and (3) ‘even’ representations. The latter case conjecturally can only occur if the image of ρ is finite. Our results come in two flavours. First, we prove a general result for Artin representations, conditional on a strengthening of the Leopoldt Conjecture. Second, when K is an imaginary quadratic field, we prove an unconditional result that implies the existence of ‘many’ positive-dimensional components (of certain deformation spaces) that do not contain infinitely many classical points. Also included are some speculative remarks about ‘p-adic functoriality’, as well as some remarks on how our methods should apply to n-dimensional representations of Gal($\math{\bar{\QQ}}$/ℚ) when n > 2.
LSD and AMAZE: the mass-metallicity relation at z > 3
Authors: Mannucci F. , Maiolino R.
Published: December 2008

We present the first results on galaxy metallicity evolution at z > 3 from two projects, LSD (Lyman-break galaxies Stellar populations and Dynamics) and AMAZE (Assessing the Mass Abundance redshift Evolution). These projects use deep near-infrared spectroscopic observations of a sample of ~40 LBGs to estimate the gas-phase metallicity from the emission lines. We derive the mass-metallicity relation at z > 3 and compare it with the same relation at lower redshift. Strong evolution from z = 0 and z = 2 to z = 3 is observed, and this finding puts strong constraints on the models of galaxy evolution. These preliminary results show that the effective oxygen yields do not increase with stellar mass, implying that the simple outflow model does not apply at z > 3.
Connecting high-redshift galaxy populations through observations of local Damped Lyman Alpha dwarf galaxies
Authors: Schulte-Ladbeck Regina E.
Published: December 2008

I report on observations of the z=t 0.01 dwarf galaxy SBS1543+593 which is projected onto the background QSO HS1543+5921. As a star-forming galaxy first noted in emission, this dwarf is playing a pivotal role in our understanding of high-redshift galaxy populations, because it also gives rise to a Damped Lyman Alpha system. This enabled us to analyze, for the first time, the chemical abundance of α elements in a Damped Lyman Alpha galaxy using both, emission and absorption diagnostics. We find that the abundances agree with one another within the observational uncertainties. I discuss the implications of this result for the interpretation of high-redshift galaxy observations. A catalog of dwarf-galaxy–QSO projections culled from the Sloan Digital Sky Survey is provided to stimulate future work.
Chemical enrichment and feedback in low metallicity environments: constraints on galaxy formation
Authors: Matteucci Francesca
Published: December 2008

Chemical evolution models for dwarf metal poor galaxies, including dwarf irregulars and dwarf spheroidals will be presented. The main ingredients necessary to build detailed models of chemical evolution including stellar nucleosynthesis, supernova progenitors, stellar lifetimes and stellar feedback will be discussed. The stellar feedback will be analysed in connection with the development of galactic winds in dwarf galaxies and their effects on the predicted abundances and abundance ratios. Model results concerning α-elements (O, Mg, Si, Ca), Fe and s-and r-process elements will be discussed and compared with the most recent observational data for metal poor galaxies of the Local Group. We will show how the study of abundance ratios versus abundances can represent a very powerful tool to infer constraints on galaxy formation mechanisms. In this framework, we will discuss whether, on the basis of their chemical properties, the dwarf galaxies of the Local Group could have been the building blocks of the Milky Way.
The importance of following the evolution of the dust in galaxies on their SEDs
Authors: Schurer A. , Calura F. , Silva L. , Pipino A. , Granato G. L. , Matteucci F. , Maiolino R.
Published: December 2008

We present photometric evolution of galaxies in which, in addition to the stellar component, the effects of an evolving dusty interstellar medium have been included with particular care. Starting from the work of Calura, Pipino & Matteucci (2008), in which chemical evolution models have been used to study the evolution of both the gas and dust components of the interstellar medium in spiral, elliptical and irregular galaxies, it has been possible to combine these models with a spectrophotometric stellar synthesis code that includes dust reprocessing (GRASIL) (Silva 1998) to analyse the evolution of the Spectral Energy Distributions (SED) of these galaxies. We test our models against observed SEDs both in the local universe and at high redshift. The importance of following the dust evolution is investigated by comparing our results with those obtained by adopting simple assumptions to treat this component. Possible errors from assuming a Milky Way dust composition and a dust-to-gas ratio scaling with the metallicity particularly in young galaxies, ellipticals and low metallicity galaxies are highlighted.
Supernovae and their Evolution in a Low Metallicity ISM
Authors: Chevalier Roger A.
Published: December 2008

Observations of core collapse supernovae and their progenitors generally support expectations of increasing mass loss with increasing initial mass. Mass loss rates are expected to decline at lower metallicity, and there are prospects for directly testing this for the red supergiant progenitors of Type IIP supernovae. However, there are indications that mass loss rates for high mass early type stars may be overestimated and that there are mass loss mechanisms that do not decline at lower metallicity. In this case, there may be supernova emission from strong circumstellar interaction even at low metallicity. Although there is evidence for dust formation in freely expanding ejecta of supernovae, the quantities are relatively small. Another promising site of dust formation is the circumstellar interaction region, but this should occur in only a fraction of supernovae.
The Star Formation History of the GRB 050730 Host Galaxy
Authors: Calura Francesco
Published: December 2008

The long GRB 050730 observed at redshiftz~ 4 allowed the determination of the elemental abundances for a set of different chemical elements. We use detailed chemical evolution models taking into account also dust production to constrain the star formation history of the host galaxy of this long GRB. For the host galaxy of GRB 050730, we derive also some dust-related quantities and the specific star formation rate, namely the star formation rate per unit stellar mass. Finally, we compare the properties of the GRB host galaxy with those of Quasar Damped Lyman Alpha absorbers.
The Gas Phase in a Low Metallicity ISM
Authors: Brinks Elias , Oh Se–Heon , Bagetakos Ioannis , Bigiel Frank , Leroy Adam , Usero Antonio , Walter Fabian , de Blok W. J. G. , Kennicutt Robert C.
Published: December 2008

We present several results from our analysis of dwarf irregular galaxies culled from The HI Nearby Galaxy Survey (THINGS). We analyse the rotation curves of two galaxies based on “bulk” velocity fields, i.e. velocity maps from which random non–circular motions are removed. We confirm that their dark matter distribution is best fit by an isothermal halo model. We show that the star formation properties of dIrr galaxies resemble those of the outer parts of larger, spiral systems. Lastly, we study the large scale (3–D) distribution of the gas, and argue that the gas disk in dIrrs is thick, both in a relative, as well as in an absolute sense as compared to spirals. Massive star formation through subsequent supernova explosions is able to redistribute the bulk of the ISM, creating large cavities. These cavities are often larger, and longer–lived than in spiral galaxies.
The Metal-Poor IMF, Stellar Evolution, and Star Formation Histories
Authors: Skillman Evan D.
Published: December 2008

I present an introduction to three important subjects relevant to low metallicity star formation: the IMF, stellar evolution, and star formation histories. I will draw on observations from the LCID (Local Cosmology from Isolated Dwarfs) project to illustrate some of these topics.
Stellar Evolution in the Early Universe
Authors: Hirschi Raphael , Frischknecht Urs , Thielemann F.-K. , Pignatari Marco , Chiappini Cristina , Ekström Sylvia , Meynet Georges , Maeder André
Published: December 2008

Massive stars played a key role in the early evolution of the Universe. They formed with the first halos and started the re-ionisation. It is therefore very important to understand their evolution. In this paper, we describe the strong impact of rotation induced mixing and mass loss at very low metallicity (Z). The strong mixing leads to a significant production of primary14N,13C and22Ne. Mass loss during the red supergiant stage allows the production of Wolf-Rayet stars, type Ib,c supernovae and possibly gamma-ray bursts (GRBs) down to almostZ= 0 for stars more massive than 60M⊙. Galactic chemical evolution models calculated with models of rotating stars better reproduce the early evolution of N/O, C/O and12C/13C. We calculated the weak s-process production induced by the primary22Ne and obtain overproduction factors (relative to the initial composition,Z= 10−6) between 100-1000 in the mass range 60–90M⊙.
Stellar Archaeology: Using Metal-Poor Stars to Test Theories of the Early Universe
Authors: Frebel Anna , Johnson Jarrett L. , Bromm Volker
Published: December 2008

Constraints on the chemical yields of the first stars and supernova can be derived by examining the abundance patterns of different types of metal-poor stars. We show how metal-poor stars are employed to derive constraints of the formation of the first low-mass stars by testing a fine-structure line cooling theory. The concept of stellar archaeology, that stellar abundances truly reflect the chemical composition of the earliest times, is then addressed. The accretion history of a sample of metal-poor stars is examined in detail in a cosmological context, and found to have no impact on the observed abundances. Predictions are made for the lowest possible Fe and Mg abundances observable in the Galaxy, [Fe/H]min = −7.5 and [Mg/H]min = −5.5. The absence of stars below these values is so far consistent with a top-heavy IMF. These predictions are directly relevant for future surveys and the next generation of telescopes.
Probing Globular Cluster Formation in Low Metallicity Dwarf Galaxies
Authors: Johnson Kelsey E. , Hunt Leslie K. , Reines Amy E.
Published: December 2008

The ubiquitous presence of globular clusters around massive galaxies today suggests that these extreme star clusters must have been formed prolifically in the earlier universe in low-metallicity galaxies. Numerous adolescent and massive star clusters are already known to be present in a variety of galaxies in the local universe; however most of these systems have metallicities of 12 + log(O/H) > 8, and are thus not representative of the galaxies in which today's ancient globular clusters were formed. In order to better understand the formation and evolution of these massive clusters in environments with few heavy elements, we have targeted several low-metallicity dwarf galaxies with radio observations, searching for newly-formed massive star clusters still embedded in their birth material. The galaxies in this initial study are HS 0822+3542, UGC 4483, Pox 186, and SBS 0335-052, all of which have metallicities of 12 + log(O/H) < 7.75. While no thermal radio sources, indicative of natal massive star clusters, are found in three of the four galaxies, SBS 0335-052 hosts two such objects, which are incredibly luminous. The radio spectral energy distributions of these intense star-forming regions in SBS 0335-052 suggest the presence of ~12,000 equivalent O-type stars, and the implied star formation rate is nearing the maximum starburst intensity limit.
Low Metallicity Galaxies at z ~ 0.7: Keys to the Origins of Metallicity Scaling Laws
Authors: Rosario David J. , Hoyos Carlos , Koo David , Phillips Andrew
Published: December 2008

We present a study of remarkably luminous and unique dwarf galaxies at redshifts of 0.5 < z < 0.7, selected from the DEEP2 Galaxy Redshift survey by the presence of the temperature sensitive [OIII]λ4363 emission line. Measurements of this important auroral line, as well as other strong oxygen lines, allow us to estimate the integrated oxygen abundances of these galaxies accurately without being subject to the degeneracy inherent in the standard R23 system used by most studies. [O/H] estimates range between 1/5–1/10 of the solar value. Not surprisingly, these systems are exceedingly rare and hence represent a population that is not typically present in local surveys such as SDSS, or smaller volume deep surveys such as GOODS.

Our low-metallicity galaxies exhibit many unprecedented characteristics. With B-band luminosities close to L*, thse dwarfs lie significantly away from the luminosity-metallicity relationships of both local and intermediate redshift star-forming galaxies. Using stellar masses determined from optical and NIR photometry, we show that they also deviate strongly from corresponding mass-metallicity relationships. Their specific star formation rates are high, implying a significant burst of recent star formation. A campaign of high resolution spectroscopic follow-up shows that our galaxies have dynamical properties similar to local HII and compact emission line galaxies, but mass-to-light ratios that are much higher than average star-forming dwarfs.

The low metallicities, high specific star formation rates, and small halo masses of our galaxies mark them as lower redshift analogs of Lyman-Break galaxies, which, at z ~ 2 are evolving onto the metallicity sequence that we observe in the galaxy population of today. In this sense, these systems offer fundamental insights into the physical processes and regulatory mechanisms that drive galaxy evolution in that epoch of major star formation and stellar mass assembly.
Relationship between variability in aboveground net primary production and precipitation in global grasslands
Authors: Yang Yuanhe , Fang Jingyun , Ma Wenhong , Wang Wei
Published: December 2008

Aboveground net primary production (ANPP) is strongly correlated with annual precipitation (AP) in grassland ecosystems. However, the relationship between the interannual variation in ANPP and the variability in precipitation remains controversial. In this study, we used long‐term data of biomass and precipitation from 118 sites across global grasslands to examine the relationship between variability in ANPP and AP. Our results showed that ANPP increased with precipitation, but leveled off in humid regions, and that increased variation in precipitation led to an increase in the variability in ANPP. The relative ANPP maxima significantly increased with relative AP maxima and the relative ANPP minima also positively correlated with relative AP minima. These suggest that the fluctuations in precipitation can alter the growth of grasslands, which should be incorporated into the prediction and modeling of climate changes.
Wave dispersion and the discrete aurora: New constraints derived from high‐speed imagery
Authors: Semeter J. , Zettergren M. , Diaz M. , Mende S.
Published: December 2008

An analysis of multiscale observations of a substorm auroral breakup are presented which clarify the role of wave dispersion in the formation of elemental (<100 m) auroral structure. At coarse resolution (all‐sky white light camera, 1 frame/s), observations fit the established substorm morphology—namely, arc brightening, formation of spatial distortions, and breakup into multiple “rayed” structures. At fine‐scale resolution (electron multiplying charge‐coupled device [EMCCD] camera, 9‐degree field of view, prompt emission filter, 30 frames/s), an entirely different type of coherence is observed. The “arc,” as identified at lower resolution, is observed to be a dynamic structure composed of bifurcating elemental arcs that propagate outward from the center of an “arc packet.” This dynamic process is well captured in time‐brightness histories (keograms) along a cut bisecting the structure. The observations are interpreted with respect to theoretical predictions for inertial Alfvén wave dispersion. Specifically, the arc packets are interpreted as the B⊥ projection of the parallel electric field within the Alfvén resonant cone. Prebreakup observations are found to be qualitatively consistent with this model. However, some difficulties are encountered for the more active postbreakup period. The article includes a discussion of perspective considerations in interpreting small‐scale auroral features; in particular, it is shown that the “rayed” appearance of discrete breakup aurora is, in fact, a consequence of sharply kinked sheets viewed obliquely.
Damping of long‐wavelength kinetic Alfvén fluctuations: Linear theory
Authors: Gary S. Peter , Borovsky Joseph E.
Published: December 2008

The full electromagnetic linear dispersion equation for kinetic Alfvén fluctuations in a homogeneous, isotropic, collisionless, Maxwellian electron‐proton plasma is solved numerically in the long‐wavelength limit. At propagation sufficiently oblique to the background magnetic field Bo, the wave number dependence of the damping rate of such modes is summarized by an analytic expression which scales as k⊥2k∥ where the subscripts denote directions relative to Bo. This damping progressively (although not monotonically) increases with increasing electron and proton β, corresponding to four distinct damping regimes: nonresonant, electron Landau, proton Landau, and proton transit‐time damping.
Chemical patterns of erupting silicic magmas and their influence on the amount of degassing during ascent
Authors: Burgisser Alain , Scaillet Bruno , Harshvardhan
Published: December 2008

We present a chemical model of magma degassing based on nine volatile species part of S‐O‐H‐C‐Fe‐bearing rhyolitic melts. It is based on equilibrium, closed‐system degassing, and does not take in account the crystallization of mineral phases. For given initial conditions at depth, the model calculates the gas composition as pressure decreases, as well as physical variables controlling conduit flow. We conducted a parametric study of degassing by varying initial conditions at depth within the range typical of arc magmas and characterizing the chemical evolution of the volatile components during the ascent to the surface. The resulting complex patterns of chemical changes are controlled by four groups of interrelated parameters: (1) redox state, fH2, and H2S/SO2 ratio in the gas phase, (2) gas amount, (3) melt water content and fH2O, and (4) relative melt sulfur content, fCO2, and C/S ratio in the gas phase. The other degrees of freedom (temperature, initial pressure, and melt iron content) alter the amplitude of the chemical fluctuations during ascent, but do not change the general degassing patterns. When degassing starts at depth, volatile chemistry has little effect on the amount of degassing as measured by the evolution of porosity. Magma expansion at shallow levels, however, can be greatly affected by degassing chemistry.