bluuebunny/crossref_metadata_2025 huggingface dataset:
Oil price shocks and volatility spillovers in the Nigerian sovereign bond market
Authors: Tule Moses K. , Ndako Umar B. , Onipede Samuel F.
Published: March 2017

This paper investigates volatility spillover in the Nigerian sovereign bond market arising from oil price shocks, using Vector Autoregressive Moving Average ‐ Asymmetric Generalized Autoregressive Conditional Heteroscedasticity (VARMA‐AGARCH) model. The paper covers the period March 22, 2011 to April 14, 2016 and makes use of the daily data of the Nigerian Sovereign Bond, Brent oil and West Texas Intermediate (WTI), respectively. We endogenously and sequentially detect structural break points using the test of Bai and Perron (2003) framework. In order to accurately estimate the model, we modify it by incorporating the break points into the VARMA‐AGARCH model, a process which if ignored would lead to model misspecification. The results obtained demonstrate a significant cross‐market volatility transmission between oil and sovereign bond market with ample sensitivity to structural breaks. The study also computes optimum weight portfolio and hedge ratio both with and without structural breaks and results equally indicate sensitivity to structural breaks.
The disruptive effects of pain on multitasking in a virtual errands task
Authors: Moore David J. , Law Anna S.
Published: March 2017

Background and aims

Pain is known to have a disruptive effect on cognitive performance, but prior studies have used highly constrained laboratory tasks that lack ecological validity. In everyday life people are required to complete more complex sets of tasks, prioritising task completion and recalling lists of tasks which need to be completed, and these tasks continue to be attempted during episodes or states of pain. The present study therefore examined the impact of thermal induced pain on a simulated errand task.

Methods

Fifty-five healthy adults (36 female) performed the Edinburgh Virtual Errands Task (EVET) either during a painful thermal sensation or with no concurrent pain. Participants also completed the Experience of Cognitive Intrusion of Pain (ECIP) questionnaire to measure their self-reported cognitive impact of pain in general life.

Results

Participants who completed the EVET task in pain and who self-reported high intrusion of pain made significantly more errors than those who reported lower intrusion on the ECIP.

Conclusions

Findings here support the growing literature that suggests that pain has a significant impact on cognitive performance. Furthermore, these findings support the developing literature suggesting that this relationship is complex when considering real world cognition, and that self-report on the ECIP relates well to performance on a task designed to reflect the complexities of everyday living.

Implications

If extrapolated to chronic pain populations, these data suggest that pain during complex multitasking performance may have a significant impact on the number of errors made. For people highly vulnerable to cognitive intrusion by pain, this may result in errors such as selecting the wrong location or item to perform tasks, or forgetting to perform these tasks at the correct time. If these findings are shown to extend to chronic pain populations then occupational support to manage complex task performance, using for example diaries/electronic reminders, may help to improve everyday abilities.
Descriptive Set Theory and Forcing
Authors: Miller Arnold W.
Published: March 2017

Since their inception, the Perspectives in Logic and Lecture Notes in Logic series have published seminal works by leading logicians. Many of the original books in the series have been unavailable for years, but they are now in print once again. In this volume, the fourth publication in the Lecture Notes in Logic series, Miller develops the necessary features of the theory of descriptive sets in order to present a new proof of Louveau's separation theorem for analytic sets. While some background in mathematical logic and set theory is assumed, the material is based on a graduate course given by the author at the University of Wisconsin, Madison, and is thus accessible to students and researchers alike in these areas, as well as in mathematical analysis.
Recursion Theory
Authors: Shoenfield Joseph R.
Published: March 2017

Since their inception, the Perspectives in Logic and Lecture Notes in Logic series have published seminal works by leading logicians. Many of the original books in the series have been unavailable for years, but they are now in print once again. In this volume, the first publication in the Lecture Notes in Logic series, Shoenfield gives a clear and focused introduction to recursion theory. The fundamental concept of recursion makes the idea of computability accessible to a mathematical analysis, thus forming one of the pillars on which modern computer science rests. This introduction is an ideal instrument for teaching and self-study that prepares the reader for the study of advanced monographs and the current literature on recursion theory.
Metamathematics of First-Order Arithmetic
Authors: Hájek Petr , Pudlák Pavel
Published: March 2017

Since their inception, the Perspectives in Logic and Lecture Notes in Logic series have published seminal works by leading logicians. Many of the original books in the series have been unavailable for years, but they are now in print once again. This volume, the third publication in the Perspectives in Logic series, is a much-needed monograph on the metamathematics of first-order arithmetic. The authors pay particular attention to subsystems (fragments) of Peano arithmetic and give the reader a deeper understanding of the role of the axiom schema of induction and of the phenomenon of incompleteness. The reader is only assumed to know the basics of mathematical logic, which are reviewed in the preliminaries. Part I develops parts of mathematics and logic in various fragments. Part II is devoted to incompleteness. Finally, Part III studies systems that have the induction schema restricted to bounded formulas (bounded arithmetic).
ARE CONSUMER HEALTH CONCERNS INFLUENCING DIRECT-FROM-PRODUCER PURCHASING DECISIONS?
Authors: THAPALIYA SUDHA , INTERIS MATTHEW G. , COLLART ALBA J. , WALTERS LURLEEN M. , MORGAN KIMBERLY L.
Published: March 2017

Research has shown health concerns may motivate consumers to purchase foods sold at direct market outlets, yet connections between management of specific diseases and food purchase decisions remain unclear. We utilize a two-step decision framework to evaluate whether family incidences of six illnesses (cancer, heart disease, diabetes, obesity, back/joint pain, and Alzheimer's disease/dementia) affect decisions to buy food at farmers’ markets and farm stands. We find that cancer, diabetes, obesity, and back/joint pain influence the decision to purchase from farm stands. Disease incidences have varying directional effects on frequency of purchase for both farmers’ markets and farm stands.
MEASURING THE IMPACT OF A BONUS-MALUS SYSTEM IN FINITE AND CONTINUOUS TIME RUIN PROBABILITIES FOR LARGE PORTFOLIOS IN MOTOR INSURANCE
Authors: Afonso Lourdes B. , Cardoso Rui M. R. , Egídio dos Reis Alfredo D. , Guerreiro Gracinda Rita
Published: March 2017

Motor insurance is a very competitive business where insurers operate with quite large portfolios, often decisions must be taken under short horizons and therefore ruin probabilities should be calculated in finite time. The probability of ruin, in continuous and finite time, is numerically evaluated under the classical Cramér–Lundberg risk process framework for a large motor insurance portfolio, where we allow for a posteriori premium adjustments, according to the claim record of each individual policyholder. Focusing on the classical model for bonus-malus systems, we propose that the probability of ruin can be interpreted as a measure to decide between different bonus-malus scales or even between different bonus-malus rules. In our work, the required initial surplus can also be evaluated. We consider an application of a bonus-malus system for motor insurance to study the impact of experience rating in ruin probabilities. For that, we used a real commercial scale of an insurer operating in the Portuguese market, and we also work on various well-known optimal bonus-malus scales estimated with real data from that insurer. Results involving these scales are discussed.
Prevalence Estimate of Cerebral Palsy in Northern Alberta: Births, 2008-2010
Authors: Robertson Charlene M.T. , Ricci M. Florencia , O’Grady Kathleen , Oskoui Maryam , Goez Helly , Yager Jerome Y. , Andersen John C.
Published: March 2017

Objectives:The objectives of this study were to determine prevalence estimates of cerebral palsy (CP) among 5-year-old children in northern Alberta; to provide congenital, gestational age– and birth weight–specific, and postneonatal CP rates; and to describe motor subtypes and function.Methods:This population-based prevalence estimate study, part of the Canadian Cerebral Palsy Registry, reports confirmed CP diagnoses at age 5 years made by pediatric rehabilitation and child neurology specialists. Prevalence rates with 95% confidence intervals (CIs) used Alberta government denominators of same-age children and live births.Results:The Northern Alberta CP rate (birth years, 2008-2010) for 173 5-year-old children is 2.22 (95% CI 2.12, 2.32) per 1000 5-year-old children. The congenital CP rate is 1.99 (95% CI, 1.89-2.09) per 1000 live births; unilateral congenital CP, 1.0 (95% CI, 0.64-1.36) per 1000 live births; and postneonatal CP, 0.12 (95% CI, 0.1-0.14) per 1000 live births. Gestational age-specific rates are similar: age <28 weeks, 27.2 (95% CI, 23.05-31.35) and 28 to 31 weeks, 29.5 (95% CI, 25.78-33.22). Motor subtypes for 169 children (data missing, 4; male, 97; postnatal, 9) are: spastic, 148 (87.6%) including 31 (20.9%) with diplegia, 10 (6.8%) triplegia, 33 (22.2%) quadriplegia, 74 (50%) hemiplegia/monoplegia); and dyskinetic, 18 (10.6%) and ataxic, 3 (1.8%). A total of 107 (63.3%) ambulate without assistive devices and 111(65.7%) handle most objects with their hands independently.Conclusions:This is the fourth Canadian CP prevalence study; one from Quebec used a similar case ascertainment approach and two 1980s studies from Alberta and British Columbia used administrative databases. Northern Alberta CP rates are comparable with other developed countries. The hemiplegic subtype is the most common. Rates among preterm children have declined but are similar for the <28 and 28 to 31 gestation-week groups.
Individuals’ Self-Defining Memories As Reflecting Their Strength and Weaknesses
Authors: Goldner Limor , Scharf Miri
Published: March 2017

The associations between attachment orientations, temperament, resilience, and various dimensions of self-defining memories were examined in 83 female Israeli adolescents and young adults. Resiliency and positive temperament were associated with positive qualities of memories, whereas negative emotionality and reactivity were associated with poor recollection quality. Lower levels of fearful attachment orientation were associated with interpersonal memories and mixed emotions in memories, and a profound-distrust attachment orientation was associated with life-threatening memories. The study highlights the contribution of these qualities to recollections and underscores the contribution to theory and practical implications.
HOD, V AND THE GCH
Authors: GOLSHANI MOHAMMAD
Published: March 2017

Starting from large cardinals we construct a model of ZFC in which the GCH fails everywhere, but such that GCH holds in its HOD. The result answers a question of Sy Friedman. Also, relative to the existence of large cardinals, we produce a model of ZFC + GCH such that GCH fails everywhere in its HOD.
DISJOINT AMALGAMATION IN LOCALLY FINITE AEC
Authors: BALDWIN JOHN T. , KOERWIEN MARTIN , LASKOWSKI MICHAEL C.
Published: March 2017

We introduce the concept of a locally finite abstract elementary class and develop the theory of disjoint$\left( { \le \lambda ,k} \right)$-amalgamation) for such classes. From this we find a family of complete ${L_{{\omega _1},\omega }}$ sentences ${\phi _r}$ that a) homogeneously characterizes ${\aleph _r}$ (improving results of Hjorth [11] and Laskowski–Shelah [13] and answering a question of [21]), while b) the ${\phi _r}$ provide the first examples of a class of models of a complete sentence in ${L_{{\omega _1},\omega }}$ where the spectrum of cardinals in which amalgamation holds is other that none or all.
DISTAL AND NON-DISTAL PAIRS
Authors: HIERONYMI PHILIPP , NELL TRAVIS
Published: March 2017

The aim of this note is to determine whether certain non-o-minimal expansions of o-minimal theories which are known to be NIP, are also distal. We observe that while tame pairs of o-minimal structures and the real field with a discrete multiplicative subgroup have distal theories, dense pairs of o-minimal structures and related examples do not.
TOPOLOGICAL CELL DECOMPOSITION AND DIMENSION THEORY IN P-MINIMAL FIELDS
Authors: KOVACSICS PABLO CUBIDES , DARNIÈRE LUCK , LEENKNEGT EVA
Published: March 2017

This paper addresses some questions about dimension theory for P-minimal structures. We show that, for any definable set A, the dimension of $\bar A\backslash A$ is strictly smaller than the dimension of A itself, and that A has a decomposition into definable, pure-dimensional components. This is then used to show that the intersection of finitely many definable dense subsets of A is still dense in A. As an application, we obtain that any definable function $f:D \subseteq {K^m} \to {K^n}$ is continuous on a dense, relatively open subset of its domain D, thereby answering a question that was originally posed by Haskell and Macpherson.

In order to obtain these results, we show that P-minimal structures admit a type of cell decomposition, using a topological notion of cells inspired by real algebraic geometry.
BINARY PRIMITIVE HOMOGENEOUS SIMPLE STRUCTURES
Authors: KOPONEN VERA
Published: March 2017

Suppose that ${\cal M}$ is countable, binary, primitive, homogeneous, and simple. We prove that the SU-rank of the complete theory of ${\cal M}$ is 1 and hence 1-based. It follows that ${\cal M}$ is a random structure. The conclusion that ${\cal M}$ is a random structure does not hold if the binarity condition is removed, as witnessed by the generic tetrahedron-free 3-hypergraph. However, to show that the generic tetrahedron-free 3-hypergraph is 1-based requires some work (it is known that it has the other properties) since this notion is defined in terms of imaginary elements. This is partly why we also characterize equivalence relations which are definable without parameters in the context of ω-categorical structures with degenerate algebraic closure. Another reason is that such characterizations may be useful in future research about simple (nonbinary) homogeneous structures.
NIP FOR THE ASYMPTOTIC COUPLE OF THE FIELD OF LOGARITHMIC TRANSSERIES
Authors: GEHRET ALLEN
Published: March 2017

The derivation on the differential-valued field Tlogof logarithmic transseries induces on its value group${{\rm{\Gamma }}_{{\rm{log}}}}$a certain mapψ. The structure${\rm{\Gamma }} = \left( {{{\rm{\Gamma }}_{{\rm{log}}}},\psi } \right)$is a divisible asymptotic couple. In [7] we began a study of the first-order theory of$\left( {{{\rm{\Gamma }}_{{\rm{log}}}},\psi } \right)$where, among other things, we proved that the theory$T_{{\rm{log}}} = Th\left( {{\rm{\Gamma }}_{{\rm{log}}} ,\psi } \right)$has a universal axiomatization, is model complete and admits elimination of quantifiers (QE) in a natural first-order language. In that paper we posed the question whetherTloghas NIP (i.e., the Non-Independence Property). In this paper, we answer that question in the affirmative:Tlogdoes have NIP. Our method of proof relies on a complete survey of the 1-types ofTlog, which, in the presence of QE, is equivalent to a characterization of all simple extensions${\rm{\Gamma }}\left\langle \alpha \right\rangle$of${\rm{\Gamma }}$. We also show thatTlogdoes not have the Steinitz exchange property and we weigh in on the relationship between models ofTlogand the so-calledprecontraction groupsof [9].
A MODEL-THEORETIC CHARACTERIZATION OF MONADIC SECOND ORDER LOGIC ON INFINITE WORDS
Authors: GHILARDI SILVIO , VAN GOOL SAMUEL J.
Published: March 2017

Monadic second order logic and linear temporal logic are two logical formalisms that can be used to describe classes of infinite words, i.e., first-order models based on the natural numbers with order, successor, and finitely many unary predicate symbols.

Monadic second order logic over infinite words (S1S) can alternatively be described as a first-order logic interpreted in${\cal P}\left( \omega \right)$, the power set Boolean algebra of the natural numbers, equipped with modal operators for ‘initial’, ‘next’, and ‘future’ states. We prove that the first-order theory of this structure is the model companion of a class of algebras corresponding to a version of linear temporal logic (LTL) without until.

The proof makes crucial use of two classical, nontrivial results from the literature, namely the completeness of LTL with respect to the natural numbers, and the correspondence between S1S-formulas and Büchi automata.
MARGINALIA ON A THEOREM OF WOODIN
Authors: BLANCK RASMUS , ENAYAT ALI
Published: March 2017

Let$\left\langle {{W_n}:n \in \omega } \right\rangle$be a canonical enumeration of recursively enumerable sets, and supposeTis a recursively enumerable extension of PA (Peano Arithmetic) in the same language. Woodin (2011) showed that there exists an index$e \in \omega$(that depends onT) with the property that if${\cal M}$is a countable model ofTand for some${\cal M}$-finite sets,${\cal M}$satisfies${W_e} \subseteq s$, then${\cal M}$has an end extension${\cal N}$that satisfiesT+We=s.

Here we generalize Woodin’s theorem to all recursively enumerable extensionsTof the fragment${{\rm{I}\rm{\Sigma }}_1}$of PA, and remove the countability restriction on${\cal M}$whenTextends PA. We also derive model-theoretic consequences of a classic fixed-point construction of Kripke (1962) and compare them with Woodin’s theorem.
PERTURBATION OF BANACH SPACE OPERATORS WITH A COMPLEMENTED RANGE
Authors: DUGGAL B. P. , KUBRUSLY C. S.
Published: March 2017

Let${\mathcal C}[{\mathcal X}]$be any class of operators on a Banach space${\mathcal X}$, and let${Holo}^{-1}({\mathcal C})$denote the class of operatorsAfor which there exists a holomorphic functionfon a neighbourhood${\mathcal N}$of the spectrum σ(A) ofAsuch thatfis non-constant on connected components of${\mathcal N}$andf(A) lies in${\mathcal C}$. Let${{\mathcal R}[{\mathcal X}]}$denote the class of Riesz operators in${{\mathcal B}[{\mathcal X}]}$. This paper considers perturbation of operators$A\in\Phi_{+}({\mathcal X})\Cup\Phi_{-}({\mathcal X})$(the class of all upper or lower [semi] Fredholm operators) by commuting operators in$B\in{Holo}^{-1}({\mathcal R}[{\mathcal X}])$. We prove (amongst other results) that if πB(B) = ∏mi= 1(B− μi) is Riesz, then there exist decompositions${\mathcal X}=\oplus_{i=1}^m{{\mathcal X}_i}$and$B=\oplus_{i=1}^m{B|_{{\mathcal X}_i}}=\oplus_{i=1}^m{B_i}$such that: (i) If λ ≠ 0, then$\pi_B(A,\lambda)=\prod_{i=1}^m{(A-\lambda\mu_i)^{\alpha_i}} \in\Phi_{+}({\mathcal X})$(resp.,$\in\Phi_{-}({\mathcal X})$) if and only if$A-\lambda B_0-\lambda\mu_i\in\Phi_{+}({\mathcal X})$(resp.,$\in\Phi_{-}({\mathcal X})$), and (ii) (case λ = 0)$A\in\Phi_{+}({\mathcal X})$(resp.,$\in\Phi_{-}({\mathcal X})$) if and only if$A-B_0\in\Phi_{+}({\mathcal X})$(resp.,$\in\Phi_{-}({\mathcal X})$), whereB0= ⊕mi= 1(Bi− μi); (iii) if$\pi_B(A,\lambda)\in\Phi_{+}({\mathcal X})$(resp.,$\in\Phi_{-}({\mathcal X})$) for some λ ≠ 0, then$A-\lambda B\in\Phi_{+}({\mathcal X})$(resp.,$\in\Phi_{-}({\mathcal X})$).
Building the Rule of War: Postconflict Institutions and the Micro-Dynamics of Conflict in Eastern DR Congo
Authors: Lake Milli
Published: March 2017

Why have peace-building and reconstruction efforts so frequently failed to create durable institutions that can deter or withstand resurgent violence in volatile sites of cyclical conflict? Extant theory predicts that new institutions can help overcome violence and mitigate commitment problems in postconflict contexts by reducing uncertainty in inherently uncertain environments. By contrast, this article argues that postconflict institutions often prove limited in their abilities to contribute to durable peace because they offer wartime elites new venues in which to pursue conflict-era agendas. Through a micro-analysis of efforts to build the rule of law in eastern Democratic Republic of Congo, I demonstrate that wartime elites capture and instrumentalize new legal institutions to maximize their intra- and inter-organizational survival; to pursue economic, military, and political agendas behind the scenes; and, in some cases, to prepare for an imminent return to war.
Validation of microsatellite molecular markers linked with resistance toBipolaris sorokinianain wheat (Triticum aestivumL.)
Authors: TEMBO B. , SIBIYA J. , TONGOONA P. , TEMBO L.
Published: March 2017

Spot blotch disease caused byBipolaris sorokiniana(Sacc.) Shoem causes yield losses and reduces grain quality in wheat. Molecular markers reported to be linked with resistance toB. sorokinianacould accelerate the identification of resistant genotypes as they are independent of the environmental effect. However, before they can be utilized for marker assisted selection (MAS), validation in an independent population is required. The objective of the present study was therefore to validate three simple sequence repeat (SSR) molecular markers (Xwgm570, Xgwm544andXgwm437) linked with resistance toB. sorokiniana.The markers were validated using 66 wheat genotypes comprising 11 parental genotypes and 55 F2progenies. Single marker analysis was performed using simple linear regression to ascertain the relationship between the marker and the trait. All the markers were confirmed to be associated with resistance. They all gave significant association with resistance toB. sorokiniana.The markers amplified DNA fragments in the resistant parental genotypes that were similar to those observed in resistant F2progenies, but absent in the susceptible ones. Hence, these markers could be useful in increasing the efficiency of selection for resistance toB. sorokinianain wheat breeding. Since theR2values are low, a combination of two or three SSR markers can be employed during MAS. This was evident by the multiple linear equation which gave a combinedR2value of 18·0%, obtained from the inclusion of all three markers.
Length-weight relationships for 48 fish species of the Gediz estuary, in İzmir Bay (Central Aegean Sea, Turkey)
Authors: Kara Alı , Sağlam Cemıl , Acarli Denız , Cengız Özgür
Published: March 2017

Length-weight relationships were calculated for 48 fish species from İzmir Bay in the Aegean Sea, Turkey. A total of 3584 fish specimens were captured with beach seine, handline, fyke net, scoop net, castnet and trammel net in 2010–2014. The sample size ranged from three individuals for Squatina squatina to 140 for Mugil cephalus. R2 values varied between 0.95 for Pomatoschistus bathi and 0.99 for Argyrosomus regius, Chelon labrosus and Mugil cephalus. All regressions were highly significant (P < 0.001). Values of the exponent b in the length-weight regression (W = aLb) ranged from 2.750 for S. squatina to 3.514 for Syngnathus acus and the median value was 3.134 with 25–75% of the values ranging between 3.030 and 3.218.
Usefulness of intracardiac echocardiography for the diagnosis of infective endocarditis following percutaneous pulmonary valve replacement
Authors: Bouajila Sara , Chalard Aurélie , Dauphin Claire
Published: March 2017

Infective endocarditis is a serious complication occurring after percutaneous pulmonary valve replacement with a Melody valve; it is of uncertain incidence, and presents a challenging diagnosis. Vegetations may be difficult to visualise with transthoracic and transoesophageal echocardiography. We report the role of intracardiac echocardiography in this condition by confirming the prosthesis involvement.
Effect of Cu on Nanoscale Precipitation Evolution and Mechanical Properties of a Fe–NiAl Alloy
Authors: Shen Qin , Chen Hao , Liu Wenqing
Published: March 2017

The microstructural evolution of precipitation in two model alloys, Fe–NiAl and Fe–NiAl–Cu, was investigated during aging at 500°C for different times using atom probe tomography (APT). The APT results reveal that the addition of Cu effectively increases the number density of NiAl precipitates. This is attributed to Cu promoting the nucleation of NiAl particles by increasing the chemical driving force and decreasing the interfacial energy. The NiAl precipitates of the Fe–NiAl–Cu alloy grow and coarsen at a slower rate than that of the Fe–NiAl alloy, mainly due to the slower diffusion rate of the Cu atoms. The mechanical properties of the two alloys were characterized by Vickers hardness and tension tests. It was found that the addition of Cu results in the formation of core–shell precipitates with a Cu-rich core and a NiAl shell, leading to a dramatic improvement of peak hardness and strength. The effect of Cu on precipitation strengthening is discussed in terms of chemical strength and coherency strength.
Interface Segregation and Nitrogen Measurement in Fe–Mn–N Steel by Atom Probe Tomography
Authors: Langelier Brian , Van Landeghem Hugo P. , Botton Gianluigi A. , Zurob Hatem S.
Published: March 2017

Improved understanding of the interactions between solutes and the austenite/ferrite interface can benefit modeling of ferrite growth during austenite decomposition, as the transformation kinetic is significantly affected by solutes that influence interface mobility. Solute-interface interactions dominate solute segregation at the interface in binary systems, but in multi-component alloys, solute–solute interactions may also affect segregation. In this study, interface segregation in Fe–Mn–N is examined and compared with Fe–Mn–C, to reveal the extent to which C affects the segregation of Mn. Atom probe tomography (APT) is well-suited to analyze solute concentrations across the interface, as this technique combines high spatial resolution and compositional sensitivity. Measurements of Mn show that segregation is only observed for Fe–Mn–C. This demonstrates that Mn segregation is primarily driven by an affinity for C, which also segregates to the interface. However, the measurement of N in steels by APT may be affected by a variety of experimental factors. Therefore, in verifying the Fe–Mn–N result, systematic examination is conducted on the influence of pulsing method (voltage versus laser), sample preparation (ion milling versus electropolishing), and vacuum storage on the measured N concentration. Both laser pulsing and focused ion beam sample preparation are observed to decrease the apparent N concentration.
The Application of Contrast Media for In Vivo Feature Enhancement in X-Ray Computed Tomography of Soil-Grown Plant Roots
Authors: Keyes Samuel D. , Gostling Neil J. , Cheung Jessica H. , Roose Tiina , Sinclair Ian , Marchant Alan
Published: March 2017

The use of in vivo X-ray microcomputed tomography (μCT) to study plant root systems has become routine, but is often hampered by poor contrast between roots, soil, soil water, and soil organic matter. In clinical radiology, imaging of poorly contrasting regions is frequently aided by the use of radio-opaque contrast media. In this study, we present evidence for the utility of iodinated contrast media (ICM) in the study of plant root systems using μCT. Different dilutions of an ionic and nonionic ICM (Gastrografin 370 and Niopam 300) were perfused into the aerial vasculature of juvenile pea plants via a leaf flap (Pisum sativum). The root systems were imaged via μCT, and a variety of image-processing approaches used to quantify and compare the magnitude of the contrast enhancement between different regions. Though the treatment did not appear to significantly aid extraction of full root system architectures from the surrounding soil, it did allow the xylem and phloem units of seminal roots and the vascular morphology within rhizobial nodules to be clearly visualized. The nonionic, low-osmolality contrast agent Niopam appeared to be well tolerated by the plant, whereas Gastrografin showed evidence of toxicity. In summary, the use of iodine-based contrast media allows usually poorly contrasting root structures to be visualized nondestructively using X-ray μCT. In particular, the vascular structures of roots and rhizobial nodules can be clearly visualized in situ.
Study of the growth of massive galaxies based on their outer stellar populations
Authors: Karabal Emin
Published: March 2017

The outskirts of early-type galaxies (ETGs) play a key role to shed light on the mass assembly of galaxies. Deep imaging has become one of the main tools to study these regions, however artificial halos caused by bright sources hampers the photometric analysis. To get around the problem, extended PSFs are built and deconvolution is performed on images.
Extended HI disks in nearby spiral galaxies
Authors: Bosma Albert
Published: March 2017

In this short write-up, I will concentrate on a few topics of interest. In the 1970s I found very extended HI disks in galaxies such as NGC 5055 and NGC 2841, out to 2 - 2.5 times the Holmberg radius. Since these galaxies are warped, a “tilted ring model” allows rotation curves to be derived, and evidence for dark matter to be found. The evaluation of the amount of dark matter is hampered by a disk-halo degeneracy, which can possibly be broken by observations of velocity dispersions in both the MgI region and the CaII region.
On the merger origin of nuclear star clusters
Authors: Tsatsi Athanasia , Mastrobuono-Battisti Alessandra
Published: March 2017

Nuclear Star Clusters (NSCs) are commonly observed in the centers of most galaxies, including our Milky Way (MW). While their study can reveal important information about the innermost regions of galaxies, the physical processes regulating their formation are still poorly understood. We explore a possible merger origin of NSCs by studying direct N-body simulations of globular clusters (GCs) that are initially randomly distributed in the outskirts and consecutively infall to the center of a MW-like nuclear bulge. We find that the NSC that forms through this process shows a significant amount of rotation, and both morphological and kinematic properties are comparable with observations of the MW NSC. We show that no fine-tuning of the orientation of the infalling GCs is necessary to result in a rotating NSC. This study shows the plausibility of the cluster infall scenario and can help towards setting better constraints to the formation history of NSCs.
Accretion phenomena in nearby star-forming dwarf galaxies
Authors: Annibali F. , Tosi M. , Aloisi A. , Bellazzini M. , Buzzoni A. , Cignoni M. , Ciotti L. , Cusano F. , Nipoti C. , Sacchi E. , Paris D. , Romano D.
Published: March 2017

We present two pilot studies for the search and characterization of accretion events in star-forming dwarf galaxies. Our strategy consists of two complementary approaches: i) the direct search for stellar substructures around dwarf galaxies through deep wide-field imaging, and ii) the characterization of the chemical properties in these systems up to large galacto-centric distances. We show our results for two star-forming dwarf galaxies, the starburst irregular NGC 4449, and the extremely metal-poor dwarf DDO 68.
Creating lenticular galaxies with mergers
Authors: Querejeta Miguel , Eliche-Moral M. Carmen , Tapia Trinidad , Borlaff Alejandro , van de Ven Glenn , Lyubenova Mariya , Martig Marie , Falcón-Barroso Jesús , Méndez-Abreu Jairo , Zamorano Jaime , Gallego Jesús
Published: March 2017

Lenticular galaxies (S0s) represent the majority of early-type galaxies in the local Universe, but their formation channels are still poorly understood. While galaxy mergers are obvious pathways to suppress star formation and increase bulge sizes, the marked parallelism between spiral and lenticular galaxies (e.g. photometric bulge–disc coupling) seemed to rule out a potential merger origin. Here, we summarise our recent work in which we have shown, throughN-body numerical simulations, that disc-dominated lenticulars can emerge from major mergers of spiral galaxies, in good agreement with observational photometric scaling relations. Moreover, we show that mergers simultaneously increase the light concentration and reduce the angular momentum relative to their spiral progenitors. This explains the mismatch in angular momentum and concentration between spirals and lenticulars recently revealed by CALIFA observations, which is hard to reconcile with simple fading mechanisms (e.g. ram-pressure stripping).
Redshift evolution of Tully-Fisher relation
Authors: Ferrero Ismael , Abadi Mario G.
Published: March 2017

Using the eagle cosmological simulation of galaxy formation we test the ability of the ΛCDM cosmological model to reproduce the Tully-Fisher relation (TFR) and its redshift evolution. We find that our simulated galaxies follow a TFR that is in good agreement with observed results up to z = 1, indicating no evolution in the slope and a weak decrease in the zero-point.
Spiral patterns beyond the optical radius: numerical simulations and synthetic HI observations
Authors: Khoperskov Sergey , Bertin Giuseppe
Published: March 2017

The outer parts of many galaxy disks exhibit extended spiral arms far beyond the optical radius. To understand the nature and the origin of such outer spiral structure, we investigate the propagation in the outer gaseous regions of large-scale spiral density waves excited in the bright optical disk. By means of 3D hydrodynamical simulations, we show that spiral density waves, penetrating in the gas through the outer Lindblad resonance, can indeed give rise to relatively regular patterns outside the bright optical stellar disk. The amplitude of spiral structure increases rapidly with radius. Beyond the optical radius, spirals become nonlinear and develop small-scale features related to shear-induced instabilities. We also construct the synthetic 21-cm data cubes extracted from simulated gaseous disks. Our synthetic HI observations point to the existence of specific kinematical features related to the presence of spiral pattern perturbations that should be found in deep HI observations.
Spatially-resolved stellar populations of nearby galaxies in multi-filter surveys
Authors: Roman Izaskun San , Cenarro A. Javier , Díaz-García Luis A. , López-Sanjuan Carlos , Varela Jesús ,   the J-PLUS Team
Published: March 2017

We have developed a new technique using a novel approach to analyze unresolved stellar populations of spatially-resolved galaxies based on large sky multi-filter surveys. We have successfully applied this technique to 42 early-type galaxies in the ALHAMBRA survey. In agreement with some previous work, we find the gradients of early-type galaxies to be on average slightly positive in age and negative in metallicity at large radii (R > Reff). These mildly negative metallicity gradients support a merging scenario. The positive/flat age gradients could support a more uniformly distributed star formation or even secondary burst triggered by mergers.
Truncated disc surface brightness profiles produced by flares
Authors: Borlaff Alejandro , Eliche-Moral M. Carmen , Beckman John , Font Joan
Published: March 2017

Previous studies have discarded that flares in galactic discs may explain the truncation that are frequently observed in highly-inclined galaxies (Kregel et al. 2002). However, no study has systematically analysed this hypothesis using realistic models for the disc, the flare and the bulge. We derive edge-on and face-on surface brightness profiles for a series of realistic galaxy models with flared discs that sample a wide range of structural and photometric parameters across the Hubble Sequence, accordingly to observations. The surface brightness profile for each galaxy model has been simulated for edge-on and face-on views to find out whether the flared disc produces a significant truncation in the disc in the edge-on view compared to the face-on view or not. In order to simulate realistic images of disc galaxies, we have considered the observational distribution of the photometric parameters as a function of the morphological type for three mass bins (10 < log10(M/M⊙) < 10.7, 10.7 < log10(M/M⊙) < 11 and log10(M/M⊙) > 11), and four morphological type bins (S0–Sa, Sb–Sbc, Sc–Scd and Sd–Sdm). For each mass bin, we have restricted the photometric and structural parameters of each modelled galaxy to their characteristic observational ranges (μ0, disc, μeff, bulge, B/T, Mabs, reff, nbulge, hR, disc) and the flare in the disc (hz, disc/hR, disc, ∂hz, disc/∂R, see de Grijs & Peletier 1997, Graham 2001, López-Corredoira et al. 2002, Yoachim & Dalcanton 2006, Bizyaev et al. 2014, Mosenkov et al. 2015).

Contrary to previous claims, the simulations show that realistic flared disks can be responsible for the truncations observed in many edge-on systems, preserving the profile of the non-flared analogous model in face-on view. These breaks reproduce the properties of the weak-to-intermediate breaks observed in many real Type-II galaxies in the diagram relating the radial location of the break (RbrkII) in units of the inner disk scale-length with the break strength S (Laine et al. 2014). Radial variation of the scale-height of the disc (flaring) can explain the existence of many breaks in edge-on galaxies, especially of those with low break strengths $S=\log _{10}\frac{h_{o}}{h_{i}} \sim \ [-0.3,-0.1]$.
Evolution of the anti-truncated stellar profiles of S0 galaxies since z=0.6 in the SHARDS survey
Authors: Borlaff Alejandro , Eliche-Moral M. Carmen , Beckman John , Pérez-González Pablo G. , Font Joan
Published: March 2017

Lenticular galaxies (S0s) are more likely to host anti-truncated (Type III) stellar discs than galaxies of later Hubble types. Previous work on Type-III S0s at z = 0 revealed that the characteristic parameters of the breaks obey tight scaling relations (Borlaff et al. 2014). These relation are similar in both S0’s and spirals, in optical and NIR, and for barred and non-barred galaxies (Eliche-Moral et al. 2015). We have analysed 3DHST images (Brammer et al. 2012) of S0 galaxies from the SHARDS survey (Pérez-González et al. 2013) in order to investigate if E/S0 and S0 galaxies with anti-truncated stellar profiles up to z ~ 0.6 follow similar scaling relations compared to the local sample. We find that the characteristic photometric parameters of Type-III S0s at 0.4 < z < 0.6 obey analogous scaling relations to those observed in their local counterparts, lying on top of the extrapolations of the local trends towards brighter magnitudes in several photometric diagrams and sharing similar trends and values in the hi – RbrkIII, ho – RbrkIII and hi – ho diagrams. We have measured the offsets in magnitudes between two subsets of the z ~ 0.5 and z = 0 samples with similar masses (log 10M/M⊙ ~ 10.7). The median offsets are: ΔμbrkIII = − 2.23+0.46−0.62, Δμ0, i = − 2.61+0.31−0.26 and Δμ0, o = − 2.31+0.57−0.78 mag arcsec-2. We find that PSF corrections in our images do not significantly affect the scaling relations obtained in our 0.2 < z < 0.6 sample. In conclusion, the existence of similar scaling relations in Type-III S0 discs since z ~ 0.6 implies that the structures of the inner and outer discs in anti-truncated S0s have been similarly linked in the last ~ 6 Gyr, posing strong constraints to the processes proposed to explain their formation.
Galaxies Unveiled: Rest-frame UV Clumps at 0.5 < z < 1.5
Authors: Soto Emmaris , de Mello Duilia F. , Rafelski Marc A. , Gardner Jonathan P. , Koekemoer Anton M.
Published: March 2017

Studies of high redshift galaxies reveal compact sub-galactic regions of star formation, known as ‘clumps’. These ‘clumpy’ galaxies are useful for the study of galactic outskirts by enabling us to examine the radial progression of clumps over large time scales. We use the first deep high resolution NUV image from the Hubble Space Telescope covering intermediate redshifts to explore the implications this radial progression may have on galaxy evolution. From the analysis of 209 clumpy galaxies, we find that higher redshift clumps dominate the outer regions of galactic outskirts. This indicates that clumps may be migrating from the outskirts inward toward their galactic centers.
Local analogs of high-redshift galaxies: Interstellar medium conditions
Authors: Bian Fuyan , Kewley Lisa J. , Dopita Michael A. , Juneau Stephanie
Published: March 2017

Local analog galaxies play an important role in understanding the properties of high-redshift galaxies. We present a method to select a type of local analog that closely resembles the ionized interstellar medium conditions in high-redshift galaxies. These galaxies are selected based on their locations in the [O III]/Hβ versus [N II]/Hα nebular emission-line diagnostic diagram. The ionization parameters and electron densities in these analogs are comparable to those in z ≃ 2 − 3 galaxies, but higher than those in normal SDSS galaxies by ≃ 0.6 dex and ≃ 0.9 dex, respectively. We find that the high sSFR and SFR surface density can enhance the electron densities and the ionization parameters, but still cannot fully explain the difference in ISM condition between nearby galaxies and the local analogs/high-redshift galaxies.
SITELLE at the CFHT
Authors: Rousseau-Nepton Laurie , Robert Carmelle , Drissen Laurent , Martin R. Pierre , Martin Thomas ,   the SITELLE Collaboration
Published: March 2017

SITELLE is the new imaging Fourier transform spectrograph of the Canada-France-Hawaii Telescope. It produces an impressive 4 million spectra in a single datacube in selected bandpasses from 350 to 900 nm. Its large FOV (11′x11′) and its high spatial sampling (0.32′′/pixel, seeing limited) allow us to study extended objects with an unprecedented view (Drissen et al. 2014). SITELLE’s first observations of nearby galaxies revealed its capabilities to conduct detailed studies of emission line regions.
Hot gas in Milky Way size galaxies at z=0
Authors: Roca-Fàbrega Santi , Colin Pedro , Valenzuela Octavio , Figueras Francesca , Krongold Yair
Published: March 2017

We present a new set of cosmological Milky Way size galaxy simulations using ART. In our simulations the main system has been evolved inside a 28 Mpc cosmological box with a spatial resolution of 109 pc. At z=0 our systems have an Mvir = 6 − 8 × 1011 M⊙. In several of out models we have observed how a well defined disk is formed inside the dark matter halo and the overall amount of gas and stars is comparable with MW observations. Several non-axisymmetric structures arise out of the disk: spirals, bars and also a warp. We have also observed that a huge reservoir of hot gas is present at large distances from the disk, embedded in the dark matter halo region, accounting for only a fraction of the ”missing baryons”. Gas column density, emission (EM) and dispersion (DM) measure have been computed from inside the simulated disk at a position of 8 kpc from the center and in several directions. Our preliminary results reveal that the distribution of hot gas is non-isotropic according with observations (Gupta et al. 2012, Gupta et al. 2014). Also its metallic content presents a clear bimodality what is a consequence of a recent accretion of a satellite galaxy among others. After a careful analysis we confirm that due to the anisotropy in the gas distribution a new observational parameter needs to be defined to recover the real distribution of hot gas in the galactic halo (Roca-Fàbrega et al. 2016).
The MUSE QSO Blind Survey: A Census of Absorber Host Galaxies
Authors: Straka Lorrie A. ,   the MUSE GTO consortium
Published: March 2017

Understanding the distribution of gas in galaxies and its interaction with the IGM is crucial to complete the picture of galaxy evolution. At all redshifts, absorption features seen in QSO spectra serve as a unique probe of the gaseous content of foreground galaxies and the IGM, extending out to 200 kpc. Studies show that star formation history is intimately related to the co-evolution of galaxies and the IGM. In order to study the environments traced by absorption systems and the role of inflows and outflows, it is critical to measure the emission properties of host galaxies and their halos. We overcome the challenge of detecting absorption host galaxies with the MUSE integral field spectrograph on VLT. MUSE’s large field of view and sensitivity to emission lines has allowed a never-before seen match between the number density of absorbers along QSO sightlines and the number density of emission line galaxies within 200 kpc of the QSO. These galaxies represent a sample for which previously elusive connections can be made between mass, metallicity, SFR, and absorption.
No direct coupling between bending of galaxy disc stellar age and light profiles as seen from CALIFA
Authors: Ruiz-Lara Tomás , Pérez Isabel , Florido Estrella , Sánchez-Blázquez Patricia , Méndez-Abreu Jairo , Lyubenova Mariya , Falcón-Barroso Jesús , Sánchez-Menguiano Laura , Sánchez Sebastián F. ,   the CALIFA team
Published: March 2017

Recent theoretical and observational works claim the existence of galaxies with a characteristic age profile consisting on a negative radial trend followed by a smooth age upturn in its outskirts (“U-shape”). This shape has been generally related to down-bending light distributions; however, the existence of a real link between observed Surface Brightness (SB) profiles and changes in stellar properties such as age is still unclear.
Mapping the tidally disrupting Andromeda XXVII and its stellar stream
Authors: Preston Janet , Collins Michelle , Bonaca Ana , Ibata Rodrigo , Tollerud Erik , Geha Marla ,   the PAndAS collaboration
Published: March 2017

Andromeda XXVII is a dwarf spheroidal galaxy in the outskirts of the Andromeda galaxy (M31). It appears to be dissolving in to the Northern arc of M31, and could be the remnant of a strong tidal disruption. In the upcoming months, our spectroscopic program, which has measured velocities for multiple stars within both the dwarf galaxy progenitor and its stream (using the Keck II DEIMOS telescope, as part of the PAndAS survey), will determine velocity dispersions, scale radii and metallicities of both the dwarf and the stream. This in turn may enable us to ascertain the progenitor mass profile and determine whether it is cusped or cored.
A spatially-resolved study of initial mass function in the outer Galaxy
Authors: Yasui Chikako , Izumi Natsuko , Saito Masao , Kobayashi Naoto
Published: March 2017

Outskirts of spiral galaxies, including our own, and dwarf irregular galaxies are known to have a different environment from the solar neighborhood, e.g., low metallicities ( ~ − 1 dex). Among them, the outer Galaxy is the closest and hence is so far the only site suitable for population studies of resolved stars on the same basis as solar neighborhood. We have obtained NIR images of young clusters in the outer Galaxy, using the Subaru 8.2-m telescope, and clearly resolved cluster members with mass detection limits of ~ 0.1 M⊙. Based on the fitting of K-band luminosity functions (KLFs) for four clusters, we found that the initial mass function (IMF) in the outer Galaxy is consistent with that in the solar neighborhood in terms of the high-mass slope and IMF peak. Upcoming observations with a higher spatial resolution and sensitivity, using JWST, TMT, etc., will allow us to extend spatially-resolved studies of the IMF to Local Group galaxies.