bluuebunny/crossref_metadata_2025 huggingface dataset:
Shotgun Proteomics
Authors: Banks Charles AS , Lakshminarasimhan Mahadevan , Washburn Michael P
Published: October 2014

Investigating how the protein machinery in cells functions is fundamental to biological enquiry. Technology that can identify and quantitate a multitude of unknown proteins can facilitate such investigations. Although techniques such as Western blotting are able to provide limited but useful information about a known protein if a suitable antibody is available, mass spectrometry provides a platform for the large‐scale identification and quantitation of the many unknown proteins in a typical sample. In particular, shotgun proteomics techniques have been used for studying global changes in whole proteomes, probing the subunit composition of protein complexes, and for mapping post‐translational modifications. The advent of whole genome sequencing has enabled recent advances in shotgun proteomics technology. Multidimensional protein identification technology (MudPIT), which couples mass spectrometry and multidimensional chromatography, achieves exquisitely sensitive protein detection. There are a variety of methods used to quantify the identified proteins, from isotopic labelling to ‘label free’ spectral counting.

Key Concepts:

‘Shotgun proteomics’ aims to identify all proteins present in a sample using mass spectrometry to make measurements that depend on a protein's mass.

Before mass spectrometry, proteins in a sample are digested with a protease to create a complex peptide mixture for analysis.

Peptides between approximately 10 and 30 amino acids long can generate characteristic fragmentation patterns that can be used to identify their sequences.

Chromatography is used to enrich peptides of the same kind; if enough of these enter the mass spectrometer concurrently, they can be characterised.

These homogeneous populations of peptides are isolated and fragmented inside the mass spectrometer; as these fragments are detected, MS/MS spectra are generated.

The patterns described by these MS/MS spectra are peptide ‘fingerprints’ which can be matched to predicted spectral patterns; genomic nucleic acid sequences are used to predict these spectral patterns.

Protein quantitation is possible; strategies used include counting the number of MS/MS spectra per protein obtained during the analysis (label free), or labelling proteins/peptides from two samples with different isotopes.
Insect Viruses
Authors: Possee Robert D , King Linda A
Published: October 2014

Viruses from over 16 families have been isolated from insects to date and show as much variation in structural and organisational paradigms as viruses from most other animal classes. Unique to the insect viruses is the ability of several families to produce a large pseudocrystalline occlusion body that protects the mature virus particles in the environment. Such occlusion bodies have led to these viruses evolving a complex array of associations with their insect host and in many cases causing large‐scale disease epizootics. Some of these viruses have been used for the purposes of biocontrol of insect pests in agriculture. Among the remaining nonoccluded insect viruses all of the basic structural and organisational paradigms are present in different families. Many insect viruses seem able to coexist in a single host without causing obvious disease. However, the life history strategies of their insect hosts has led the insect viruses to evolve some intriguing replicative strategies of their own that have few, if any, counterparts among the other animal viruses.

Key Concepts:

Insect viruses have genomes that may comprise double‐ or single‐stranded DNA or RNA.

Insect viruses exhibit as much structural diversity as viruses that infect any other form of life.

Insect viruses may be enveloped or non‐enveloped.

Some insect viruses may form occlusion bodies comprising virions embedded within a protein matrix.

Insect viruses may have evolved 350–400 million years ago.

Many insect viruses share genetic and structural similarities with viruses of vertebrates.

Some insect viruses are unique to invertebrate species.

Insect viruses can be highly pathogenic to their hosts or cause little or no signs of infection.

Some insect viruses have been used as biopesticides to control insect pests.
Gene Inactivation Strategies: An Update
Authors: Guo Chang‐An , O'Neill Lucas M , Ntambi James M
Published: October 2014

The ability to manipulate gene expression levels has been essential to the study of gene function and biological processes. Classically, whole body deletions of genes were generated via homologous recombination. Over the past two decades, the development of Cre‐Lox and flippase/flippase recombinase target based gene inactivation technologies allowed researchers to closely regulate the location and timing of gene expression. However, these methods are costly and time consuming. The last few years have seen a revolution in the approaches scientists use to inactivate gene expression, such as the development of highly efficient
ribonucleic acid interference (RNAi)
delivery systems and the groundbreaking genome editing technologies. Here, the authors describe the recent updates on
small interfering RNA (siRNA)
in vivo
delivery as well as the methodologies and applications of zinc‐finger nucleases, transcription activator‐like effector nucleases and clustered regularly interspaced short palindromic repeats. Equipped with these powerful tools, scientists can now rapidly modulate the expression of genes of interest and precisely modify the genomic sequences in virtually any organisms.

Key Concepts:

RNA interference (RNAi) is an endogenous post‐transcriptional gene‐regulatory mechanism mediated by noncoding RNA molecules to regulate gene expression.

Chemical modification on siRNA reduces off‐target effect, improves RNAi efficiency and enhances the stability of siRNA for
in vivo
applications.

Genome editing is a genetic approach used to directly manipulate an organism's genome by inserting, replacing, or removing DNA sequences.

Engineered nucleases, such as zinc‐finger nucleases (ZFNs), transcription activator‐like effector nucleases (TALENs) and the bacterial clustered regularly interspaced short palindromic repeat (CRISPR)/Cas (CRISPR‐associated) system enable targeted genetic modifications in cells, tissues and organisms.
Molecular Genetics of Myopathies Caused by β‐Tropomyosin Mutations
Authors: Pelin Katarina , Marttila Minttu , Wallgren‐Pettersson Carina
Published: October 2014

Mutations in the gene encoding β‐tropomyosin,
TPM2
, cause clinically and histologically overlapping congenital myopathies such as nemaline myopathy, cap myopathy and core‐rod myopathy, and often also a fibre size disproportion between type 1 and type 2 muscle fibres. In addition,
TPM2
mutations can cause distal arthrogryposis and Escobar syndrome, or unspecific myopathies with various combinations of clinical and histological features. The vast majority of the
TPM2
mutations are dominant, either
de novo
or familial. Missense mutations and in‐frame deletions or insertions of single amino acids are the most common types of mutation. Three dominant donor splice site mutations have also been described, predicted to cause exon skipping and subsequent loss of 42 amino acids. Only one recessive mutation has been identified in
TPM2
, that is, a nonsense mutation causing nemaline myopathy with Escobar syndrome. Of the 30 different
TPM2
mutations identified to date, six are gain‐of‐function mutations causing increased muscle contractility.

Key Concepts:

Dominant mutations in the
TPM2
gene cause a variety of congenital myopathies and distal arthrogryposis.

Recessive mutations in
TPM2
are rare.

Tropomyosin mutations alter actin‐tropomyosin interactions, tropomyosin dimer formation and muscle contraction.

Gain‐of‐function mutations cause increased muscle contractility.

Hypercontractile molecular phenotypes result in distal arthrogryposis and congenital myopathies with contractures.
Molecular Genetics of Inherited Glucocorticoid Deficiency
Authors: Meimaridou Eirini , Kowalczyk Julia , Metherell Louise A
Published: October 2014

Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disorder characterised by isolated glucocorticoid deficiency and resistance of the adrenal cortex to adrenocorticotropic hormone (ACTH) action. Technological advances in genetics have contributed to our better understanding of the disease.
Deoxyribonucleic acid (DNA)
sequencing technology has given insight into the genetic cause of more than 60% of FGD cases, and revealed intersecting phenotypes with other adrenal insufficiency disorders. Defects have been recognised in the ACTH receptor (
MC2R
) and its accessory protein (
MRAP
), in the mitochondrial cholesterol transfer protein STAR, in
MCM4
essential for DNA stability and repair and in
NNT
and
TXNRD2
, essential for redox homoeostasis/detoxification of ROS. The remaining causes are yet to be elucidated and using next generation sequencing tools could incriminate additional pathways responsible for the onset of the disease.

Key Concepts:

Glucocorticoid deficiency is a feature of many adrenal disorders with overlapping clinical presentations.

In most adrenal insufficiency disorders glucocorticoid deficiency is accompanied by mineralocorticoid deficiency.

Technological advances in genetics have accelerated our understanding of the genetic causes of such diseases.

Defects in novel pathways including those responsible for DNA stability and repair and those essential for redox homoeostasis/detoxification of ROS have recently been implicated in the pathogenesis of glucocorticoid deficiency.

40% of isolated glucocorticoid deficiency remains of unknown aetiology.
Gene Therapy for Severe Haemoglobin Disorders
Authors: Villamizar Olga , Chambers Christopher B , Wilber Andrew
Published: October 2014

Sickle cell disease (SCD) and β‐thalassaemia result from inherited mutations that cause structural abnormality or deficient synthesis of adult haemoglobin. Palliative therapies improve the quality/duration of life for many, but side effects result from long‐term use. Bone marrow transplantation can be curative, but is limited to individuals with a matched donor. Thus, gene delivery into the patient's haematopoietic stem cells is a desirable therapy. Lentiviral vectors encoding for erythroid‐specific expression of either γ‐ or β‐globin genes have been developed for this purpose. These vectors have been used to cure SCD and β‐thalassaemia in mouse models with positive results emerging from clinical trials. Concurrently, innovative strategies intending to reactivate endogenous γ‐globin expression or correct β‐globin mutations at the genome level are showing promise for the future. Ultimately, clinical utility of all these approaches depend on safety and efficacy so that a cure can be consistently achieved.

Key Concepts:

Sickle cell disease (SCD) and β‐thalassaemia are the most common single gene disorders, and a worldwide health concern.

The switch from foetal to adult haemoglobin production after birth marks the onset of disease.

Haematopoietic stem cell transplant is curative, but available to only a limited number of patients making gene therapy a highly desirable alternative.

Lentiviral vectors made possible the delivery of complex, erythroid‐specific globin expression cassettes into haematopoietic stem cells.

Mouse models of SCD and β‐thalassaemia have been cured with lentiviral vectors encoding for high‐level, erythroid specific expression of γ‐ and β‐globin genes.

The first adult β‐thalassaemia major patient treated with a β‐globin lentiviral vector remains transfusion‐independent and in good health 6 years after therapy.
Motion and stability of cones in a yield stress fluid
Authors: Ahonguio Fiacre , Jossic Laurent , Magnin Albert
Published: October 2014

This experimental study focuses on the creeping flow of a shear thinning yield stress fluid around conical obstacles. The flow has been analyzed in steady state and with adherence conditions. Firstly, the influences of the cone apex angle and of the Oldroyd number, that is the ratio between plastic and viscous effects, on the drag coefficient have been analyzed. Correlations have been proposed to model the evolution of this coefficient as a function of these two parameters. The analysis provides a new alternative for measuring the yield stress. Then, the kinematic fields around the cones have been analyzed. These fields enable to describe the rigid zones and the sheared zone developing around the lateral edge of the cones as a function of the cone apex angle. Moreover, the wall shear stresses estimated from the particle image velocimetry measurements have enabled to quantify the contribution of the lateral drag force in the drag force. © 2014 American Institute of Chemical Engineers AIChE J, 61: 709–717, 2015
Metal–Organic Frameworks for Oxygen Storage
Authors: DeCoste Jared B. , Weston Mitchell H. , Fuller Patrick E. , Tovar Trenton M. , Peterson Gregory W. , LeVan M. Douglas , Farha Omar K.
Published: October 2014

We present a systematic study of metal–organic frameworks (MOFs) for the storage of oxygen. The study starts with grand canonical Monte Carlo simulations on a suite of 10 000 MOFs for the adsorption of oxygen. From these data, the MOFs were down selected to the prime candidates of HKUST‐1 (Cu‐BTC) and NU‐125, both with coordinatively unsaturated Cu sites. Oxygen isotherms up to 30 bar were measured at multiple temperatures to determine the isosteric heat of adsorption for oxygen on each MOF by fitting to a Toth isotherm model. High pressure (up to 140 bar) oxygen isotherms were measured for HKUST‐1 and NU‐125 to determine the working capacity of each MOF. Compared to the zeolite NaX and Norit activated carbon, NU‐125 has an increased excess capacity for oxygen of 237 % and 98 %, respectively. These materials could ultimately prove useful for oxygen storage in medical, military, and aerospace applications.
Size‐Controlled Synthesis of Conjugated Polymer Nanoparticles in Confined Nanoreactors
Authors: Deng Sheng , Zhi Jian , Zhang Xianmei , Wu Qingqing , Ding Yun , Hu Aiguo
Published: October 2014

Soluble conjugated polymeric nanoparticles are synthesized by Suzuki‐type polycondensation of two monomers (Ax + By, x>2, y≥2) in the channel of ordered mesoporous silica‐supported carbon nanomembranes (nanoreactors). These synthesized soluble conjugated microporous polymers (SCMPs) exhibit uniform particle‐size distributions and well‐controlled particle sizes. The control of particle size stems from the fact that the polycondensations exclusively take place inside the mesochannels of the nanoreactors. Photoluminescence studies show that polymeric nanoparticles with tetraphenylethene and pyrene substructures are highly fluorescent. The combination of both physical stability and processability offered by the soluble polymeric nanoparticles makes them particularly attractive in light emitting and other optoelectronic applications.
Complementary Standoff Chemical Imaging to Map and Identify Artist Materials in an Early Italian Renaissance Panel Painting
Authors: Dooley Kathryn A. , Conover Damon M. , Glinsman Lisha Deming , Delaney John K.
Published: October 2014

Two imaging modalities based on molecular and elemental spectroscopy were used to characterize a painting by Cosimo Tura. Visible‐to‐near‐infrared (400–1680 nm) reflectance imaging spectroscopy (RIS) and X‐ray fluorescence (XRF) imaging spectroscopy were employed to identify pigments and determine their spatial distribution with higher confidence than from either technique alone. For example, Mary’s red robe was modeled through the distribution of an insect‐derived red lake (RIS map) and lead white (XRF lead map), rather than a layer of red lake on vermilion. The RIS image cube was also used to isolate the preparatory design by mapping the reflectance spectra associated with it. In conjunction with results from an earlier RIS study (1650–2500 nm) to map and identify the binding media, a more thorough understanding was gained of the materials and techniques used in the painting.
A Motif for Infinite Metal Atom Wires
Authors: Yin Xi , Warren Steven A. , Pan Yung‐Tin , Tsao Kai‐Chieh , Gray Danielle L. , Bertke Jeffery , Yang Hong
Published: October 2014

A new motif for infinite metal atom wires with tunable compositions and properties is developed based on the connection between metal paddlewheel and square planar complex moieties. Two infinite Pd chain compounds, [Pd4(CO)4(OAc)4Pd(acac)2] 1 and [Pd4(CO)4(TFA)4Pd(acac)2] 2, and an infinite PdPt heterometallic chain compound, [Pd4(CO)4(OAc)4Pt(acac)2] 3, are identified by single‐crystal X‐ray diffraction analysis. In these new structures, the paddlewheel moiety is a Pd four‐membered ring coordinated by bridging carboxylic ligands and μ2 carbonyl ligands. The planar moiety is either Pd(acac)2 or Pt(acac)2 (acac=acetylacetonate). These moieties are connected by metallophilic interactions. The results showed that these one‐dimensional metal wire compounds have photoluminescent properties that are tunable by changing ligands and metal ions. 3 can also serve as a single source precursor for making Pd4Pt bimetallic nanostructures with precise control of metal composition.
Bulky Aryloxide Ligand Stabilizes a Heterogeneous Metathesis Catalyst
Authors: Conley Matthew P. , Forrest William P. , Mougel Victor , Copéret Christophe , Schrock Richard R.
Published: October 2014

The reaction of [W(O)(CHCMe2Ph)(dAdPO)2], containing bulky 2,6‐diadamantyl aryloxide ligands, with partially dehydroxylated silica selectively yields a well‐defined silica‐supported alkylidene complex, [(SiO)W(O)(CHCMe2Ph)(dAdPO)]. This fully characterized material is a very active and stable alkene metathesis catalyst, thus allowing loadings as low as 50 ppm in the metathesis of internal alkenes. [(SiO)W(O)(CHCMe2Ph)(dAdPO)] also efficiently catalyzes the homocoupling of terminal alkenes, with turnover numbers exceeding 75 000 when ethylene is constantly removed to avoid the formation of the less reactive square‐based pyramidal metallacycle resting state.
Catalytic activities in direct arylation of novel palladiumN‐heterocyclic carbene complexes
Authors: Akkoç Senem , Gök Yetkin
Published: October 2014

Eight novel palladiumN‐heterocyclic carbene (Pd‐NHC) complexes were synthesized by the reaction of chloro 1,3‐dialkylbenzimidazolin‐2‐ylidene silver(I) complexes with bis(benzonitrile)palladium(II) chloride in dichloromethane. These eight Pd‐NHC complexes are as follows: bis[1‐phenyl‐3‐(2,4,6‐trimethylbenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II), bis[1‐phenyl‐3‐(2,3,5,6‐tetramethylbenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II), bis[1‐phenyl‐3‐(2,3,4,5,6‐pentamethylbenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II), bis[1‐phenyl‐3‐(3,4,5‐trimethoxybenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II), bis[1‐(2‐diethylaminoethyl)‐3‐(3‐methylbenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II), bis[1‐(2‐diethylaminoethyl)‐3‐(2,3,5,6‐tetramethylbenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II), bis[1‐(2‐morpholinoethyl)‐3‐naphthalenomethylbenzimidazol‐2‐ylidene]dichloropalladium(II) and bis[1‐(2‐morpholinoethyl)‐3‐(2‐methylbenzyl)benzimidazol‐2‐ylidene]dichloropalladium(II). Also, these synthesized complexes were fully characterized using Fourier transform infrared,1H NMR and13C NMR spectroscopic methods and elemental analysis techniques. These synthesized novel Pd‐NHC complexes were tested as catalysts in the direct arylation of 2‐n‐butylthiophene, 2‐n‐butylfuran and 2‐isopropylthiazole with various aryl bromides at 130°C for 1 h. The complexes showed very good catalytic activities in these reactions. Copyright © 2014 John Wiley & Sons, Ltd.
A Crown Ether Decorated Dibenzocoronene Tetracarboxdiimide Chromophore: Synthesis, Sensing, and Self‐Organization
Authors: Ma Yingjie , Marszalek Tomasz , Yuan Zhongyi , Stangenberg Rene , Pisula Wojciech , Chen Long , Müllen Klaus
Published: October 2014

A macrocyclic dibenzocoronene tetracarboxdiimide containing two benzo‐21‐crown‐7 groups has been synthesized. It shows liquid‐crystalline behavior and selectively binds Pb2+ or K+ to form 1:2 complexes in solution. The complexation leads to a significant increase of fluorescence; the surface organization of discotic columnar structures, in the solid‐state, can be controlled by selective ion binding.
Numerical solutions of the equation concerning small adiabatic oscillations of pulsating components in double star systems
Authors: Ulaş B.
Published: October 2014

The equation governing small adiabatic radial oscillations for pulsating components in close binary stars modelled by tidally and rotationally distorted Roche geometry is solved numerically. With assumed initial conditions, solutions for systems with different mass ratios are presented. The changes in relative wave amplitude with various parameters are shown. The variation of the ratio of the pulsation frequencies of distorted to undistorted stars for given mass ratio of the binary systems is also investigated. Observational evidence is examined by using two data sets that show the modelled effects, by taking into account likely practical factors. The results show that the measured frequencies and amplitudes of surface waves can vary slightly for distorted stars in comparison to undistorted ones (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AGN jets under the microscope: A divide?
Authors: Karouzos M. , Britzen S. , Witzel A. , Zensus A.J. , Eckart A.
Published: October 2014

A new paradigm for active galactic jet kinematics has emerged through detailed investigations of BL Lac objects using very long baseline radio interferometry. In this new scheme, most, if not all, jet components appear to remain stationary with respect to the core but show significant non‐radial motions. This paper presents results from our kinematic investigation of the jets of a statistically complete sample of radio‐loud flat‐spectrum active galaxies, focusing on the comparison between the jet kinematic properties of BL Lacs and flat‐spectrum radio‐quasars. It is shown that there is a statistically significant difference between the kinematics of the two AGN classes, with BL Lacs showing more bent jets, that are wider and show slower movement along the jet axis, compared to flat‐spectrum radio‐quasars. This is interpreted as evidence for helically structured jets (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A wider audience: Turning VLBI into a survey instrument
Authors: Middelberg E. , Deller A.T. , Brisken W.F. , Morgan J.S. , Norris R.P.
Published: October 2014

Radio observations using the Very Long Baseline Interferometry (VLBI) technique typically have fields of view of only a few arcseconds, due to the computational problems inherent in imaging larger fields. Furthermore, sensitivity limitations restrict observations to very compact and bright objects, which are few and far between on the sky. Thus, while most branches of observational astronomy can carry out sensitive, wide‐field surveys, VLBI observations are limited to targeted observations of carefully selected objects. However, recent advances in technology have made it possible to carry out the computations required to target hundreds of sources simultaneously. Furthermore, sensitivity upgrades have dramatically increased the number of objects accessible to VLBI observations. The combination of these two developments have enhanced the survey capabilities of VLBI observations such that it is now possible to observe (almost) any point in the sky with milli‐arcsecond resolution. In this talk I review the development of wide‐field VLBI, which has made significant progress over the last three years (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dwarf galaxies in observed and simulated galaxy clusters
Authors: Lisker T.
Published: October 2014

Galaxy clusters are populated by thousands of low‐mass galaxies, with hundreds of them already within stellar masses of 108 < M* ≤ 109.5 M⊙ and magnitudes of –16 < Mr < –19 mag. While objects in this regime are commonly termed “dwarfs”, they are not as faint and diffuse as many of the known Milky Way satellites. Their observed complexity, particularly regarding the dominant early‐type dwarf population, is still poorly understood and requires models and simulations of environmental influence on dwarfs. Studying cluster dwarf galaxies at the current time is motivated by two facts: (i) for nearby clusters, multicolour observational samples exist that are complete in the above luminosity range and cover a substantial portion of the cluster; (ii) state‐of‐the‐art semi‐analytic models based on high‐resolution N‐body simulations, reaching down to dwarf masses, have recently become available. Here I show how comparisons of models and observations can serve as a tool for studying the evolutionary history of low‐mass galaxy populations in today's clusters (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interstellar medium simulations
Authors: Breitschwerdt D. , de Avillez M.A. , Feige J. , Dettbarn C.
Published: October 2014

In this review we critically assess numerical simulations of the interstellar medium (ISM), and argue that 3D high resolution calculations are the most promising method to determine the structure of the interstellar gas and follow its evolution well into the nonlinear regime. Based on a Riemann solver adaptive mesh refinement code, we present a model, which fulfills the basic requirements of running it sufficiently long in order to erase memory effects of the initial conditions, set up a disk‐halo fountain flow cycle, for converging solutions with increasing mesh refinement. We obtain the following results: (i) in a supernova driven ISM, high Reynolds number turbulence generates structures on all scales, (ii) the volume filling factor of the hot gas is substantially reduced due to the fountain flow, (iii) gas clouds are transient shock compressed layers, (iv) more than half of the gas mass resides in thermally unstable regimes, (v) O VI is distributed in patchy mixing layers, with the derived column densities being in agreement with FUSE and Copernicus observations, (vi) the electron density distribution up to distances of 8 kpc in the disk is consistent with pulsar dispersion measure observations, provided that the electron and ionization structure are not in equilibrium, (vii) the interstellar cooling function depends both on space and time (and not only on temperature and metallicity), (viii) the Local Bubble has been produced by 14–20 supernovae about 14 Myr ago, exploding in a moving group on its path through the local ISM, (ix) the nearest supernova explosion to Earth occurred 2.2 × 106 yr ago at a distance of ∼85 pc, in agreement with measurements of the radionuclide 60Fe found in the ferromanganese crust on the ocean floor (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measuring the mass accretion rates of Herbig Ae/Be stars with X‐shooter
Authors: Pogodin M.A. , Hubrig S. , Yudin R.V. , Schöller M. , Gonzälez J.F. , Stelzer B.
Published: October 2014

We present the results of our observations of eight magnetic Herbig Ae/Be stars obtained with the X‐shooter spectrograph mounted on UT2 at the VLT. X‐shooter provides a simultaneous, medium‐resolution and high‐sensitivity spectrum over the entire wavelength range from 300 to 2500 nm. We estimate the mass accretion rates (Ṁacc) of the targets from 13 different spectral diagnostics using empiric calibrations derived previously for T Tauri‐type stars and brown dwarfs. We have estimated the mass accretion rates of our targets, which range from 2 × 10–9 to 2 × 10–7 M⊙ yr–1. Furthermore, we have found accretion rate variability with amplitudes of 0.10–0.40 dex taking place on time scales from one day to tens of days. Additional future night‐to‐night observations need to be carried out to investigate the character of Ṁacc variability in details. Our study shows that the majority of the calibration relations can be applied to Herbig Ae/Be stars, but several of them need to be re‐calibrated on the basis of new spectral data for a larger number of Herbig Ae/Be stars (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Relative astrometric and photometric measurements of visual binaries made with the Nice 76‐cm refractor in 2008
Authors: Gili R. , Prieur J.‐L.
Published: October 2014

We present relative astrometric and photometric measurements of visual binaries made in 2008, with the 76‐cm refractor of Côte d'Azur Observatory. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky imaging, speckle interferometry and the Direct Vector Autocorrelation method. We obtained 2420 new measurements of the relative position of 2225 objects, with angular separations in the range 0″.07‐11″.5, and an average accuracy of 0″.02. The mean error on the position angles is 0°.6. We managed to observe faint systems (mV ≈ 12) with large magnitude difference (up to ΔmV ≈ 5). We have thus been able to measure many systems containing red dwarf stars that had been poorly monitored since their discovery. We also measured the difference of magnitude of the two components of 376 objects with an estimated error of 0.1 mag. Finally, we provide a list of 33 newly discovered components of multiple or binary systems, which is a significant complement to our GII catalog (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical design of the new solar telescope GREGOR
Authors: Soltau D. , Volkmer R. , von der Lühe O. , Berkefeld Th.
Published: October 2014

This article describes the considerations which led to the current optical design of the new 1.5 m solar telescope GREGOR. The result is Gregorian design with two real foci in the optical train. The telescope includes a relay optic with a pupil image used by a high order adaptive optics system (AO). The optical design is described in detail and performance characteristics are given. Finally we show some verification results which prove that – without atmospheric effects – the completed telescope reaches a diffraction limited performance (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Open‐foldable domes with high‐tension textile membranes: The GREGOR dome
Authors: Hammerschlag R.H. , Kommers J.N. , Visser S. , Bettonvil F.C.M. , van Schie A.G.M. , van Leverink S.J. , Sliepen G. , Jägers A.P.L. , Schmidt W. , Volkmer R.
Published: October 2014

Double layers of high‐tensioned textile membranes were applied to the completely open‐foldable dome for the GREGOR telescope for the first time. Simultaneous climate measurements inside and outside the dome have proven the thermalinsulating capability of this double‐layer construction. The GREGOR dome is the result of the continuation of the ESO research on open‐foldable domes with textile structures, followed by the research for the DOT dome with high‐tensioned textile membranes. It cleared the way to extreme stability required for astronomical practice on high mountain sites with heavy storms and ice formation. The storm Delta with 245 km/h 1‐minute mean maximum at the location of the GREGOR caused no problems, nor did other storms afterwards. Opening and closing experiences up to wind speeds of 90 km/h were without problems. New technical developments were implemented and tested at the GREGOR dome, opening the way for application to much larger domes up to the 30 m diameter‐class range (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The GREGOR polarimetric calibration unit
Authors: Hofmann A. , Arlt K. , Balthasar H. , Bauer S.M. , Bittner W. , Paschke J. , Popow E. , Rendtel J. , Soltau D. , Waldmann T.
Published: October 2014

The new Solar telescope GREGOR is designed to observe small‐scale dynamic magnetic structures below a size of 70 km on the Sun with high spectral resolution and polarimetric accuracy. For this purpose, the polarimetric concept of GREGOR is based on a combination of post‐focus polarimeters with pre‐focus equipment for high precision calibration. The Leibniz‐Institute for Astrophysics Potsdam developed the GREGOR calibration unit which is an integral part of the telescope. We give an overview of the function and design of the calibration unit and present the results of extensive testing series done in the Solar Observatory “Einsteinturm” and at GREGOR (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using the Sun to study the impact of stellar activity on exoplanet detectability
Authors: Meunier N. , Lagrange A.M.
Published: October 2014

Stellar activity induced by spots and plages, even at a low level of activity, affects the radial velocity signatures. It is therefore crucial to determine how it impacts our ability to detect small planetary signals such as those produced by Earth‐mass planets in the habitable zone of stars. We focus on the solar case: thanks to the wealth of accurate data available, the Sun gives us a unique opportunity to test the impact of stellar activity on such detections. We use the Sun as a template and investigate in details the impact of spots and plages as well as the role played by the attenuation of convection due to the presence of magnetic activity. We present the detection limits obtained in various conditions. We find that the plage contribution due to the convective blueshift attenuation dominates the total signal, with a peak‐to‐peak amplitude over the solar cycle of about 8 m s–1, and show that this contribution would prevent the detection of the Earth around the Sun, even with forthcoming high precision radial velocity instruments, unless ways to correct the signal are found. We therefore propose practical ways to correct for the activity on various timescales from days to years, and use again the Sun to estimate the ultimate detection limits achievable once the signal is corrected from the Sun's activity. Estimations will be briefly presented. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Disks, accretion and outflows of brown dwarfs
Authors: Joergens V. , Herczeg G. , Liu Y. , Pascucci I. , Whelan E. , Alcalá J. , Biazzo K. , Costigan G. , Gully‐Santiago M. , Henning Th. , Natta A. , Rigliaco E. , Rodríguez‐Ledesma M.V. , Sicilia‐Aguilar A. , Tottle J. , Wolf S.
Published: October 2014

Characterization of the properties of young brown dwarfs are important to constraining the formation of objects at the extreme low‐mass end of the initial mass function. While young brown dwarfs share many properties with solar‐mass T Tauri stars, differences may be used as tests of how the physics of accretion/outflow and disk chemistry/dissipation depend on the mass of the central object. This article summarizes the presentations and discussions during the splinter session on “Disks, accretion and outflows of brown dwarfs” held at the CoolStars17 conference in Barcelona in June 2012. Recent results in the field of brown dwarf disks and outflows include the determination of brown dwarf disk masses and geometries based on Herschel far‐IR photometry (70–160 µm), accretion properties based on X‐Shooter spectra, and new outflow detections in the very low‐mass regime. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison between accretion‐related properties of Herbig Ae/Be and T Tauri stars
Authors: Mendigutía I.
Published: October 2014

This paper summarizes several results concerning the comparison between accretion‐related properties of cool (T Tauri; T < 7000 K, M < 1 M⊙) and hot (Herbig Ae/Be; 7000 K < T < 13000 K; 1 M⊙ < M < 6 M⊙) pre‐main sequence (PMS) stars. This comparison gives insight into the analogies/differences in the physics of the star‐disk interaction and in the physical mechanisms driving disk dissipation.

Several optical and near‐IR line luminosities used for low‐mass objects are also valid to estimate typical accretion rates for intermediate‐mass stars under similar empirical expressions. In contrast, the Hα width at 10 % of peak intensity is used as an accretion tracer for T Tauris, but is not reliable to estimate accretion rates for Herbig Ae/Bes. This can be explained as a consequence of the different stellar rotation rates that characterize both types of stars. In addition, there are similar trends when the accretion rate is related to the near‐IR colours and disk masses, suggesting that viscous accretion disk models are able to explain these trends for both T Tauri and Herbig Ae/Be stars. However, there are two major differences between cool and hot PMS objects. First, the inner gas dissipation timescale, as estimated by relating the accretion rates and the stellar ages, is slightly faster for Herbig Ae/Be stars. This could have implications on the physical mechanism able to form planets around objects more massive than the Sun. Second, the relative position of Herbig Ae/Bes with disks showing signs of inner dust clearing in the accretion rate‐disk mass plane contrasts with that of transitional T Tauri stars, when both samples are compared with “classical”, non‐evolved disks. This latter difference could be pointing to a different physical mechanism driving disk evolution, depending on the stellar regime
New insights: The accretion process and variable wind from TW Hya
Authors: Dupree A.K.
Published: October 2014

For the first time in a classical T Tauri star, we are able to trace an accretion event signaled by an hour‐long enhancement of X‐rays from the accretion shock and revealed through substantial sequential changes in optical emission line profiles. Downflowing turbulent material appears in Hα and Hβ emission. He D3 (5876 Å) broadens, coupled with an increase in flux. Two hours after the X‐ray accretion event, the optical veiling increases due to continuum emission from the hot splashdown region. The response of the stellar coronal emission to the heated photosphere follows about 2.4 hours later, giving direct evidence that the stellar corona is heated in part by accretion. Then, the stellar wind becomes re‐established. A model that incorporates the dynamics of this sequential series of events includes: an accretion shock, a cooling downflow in a supersonically turbulent region, followed by photospheric and later, coronal heating. This model naturally explains the presence of broad optical and ultraviolet lines, and affects the mass accretion rates currently determined from emission line profiles. These results, coupled with the large heated coronal region revealed from X‐ray diagnostics, suggest that current models are not adequate to explain the accretion process in young stars. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of the four catalogues by pairs, the Hipparcos, new Hipparcos, EOC‐2 and IL, by using μδ for the common 1120 stars
Authors: Damljanović G. , Cvetković Z.
Published: October 2014

We present comparison results of our Independent Latitude (IL) catalogue of μδ determinations for 1120 bright stars with the Hipparcos, new Hipparcos and Earth Orientation Catalogue (EOC‐2) values. Also, we took into consideration the EOC3 and EOC4 (recent versions of EOC catalogues). Our μδ values are based on zenith telescope observations from seven Independent Latitude (IL) observatories. The IL measures are spanning a time baseline of up to 90 years which is the key advantage to the accurate determination of μδ. The short interval of the Hipparcos satellite observations is a disadvantage for a good accuracy of stellar proper motion, especially in the case of double and multiple stars. For this reason many astrometric catalogues have appeared after the publication of the Hipparcos including our IL catalogue. These catalogues are an appropriate combination of the Hipparcos satellite and ground‐based data which yields more accurate stellar coordinates and/or their proper motions. Among various types of ground‐based observations the latitude and universal time variations obtained from several million observations of stars reduced to the Hipparcos reference system were used for this purpose. These observations were obtained during almost the entire last century and were originally used to determine the Earth Orientation Parameters. It is also possible to use these data in the inverse task of checking the accuracy of stellar coordinates and/or their proper motions listed in the Hipparcos Catalogue. Such latitude and universal time variations data are the basis of the EOC and IL catalogues. In this paper, we computed the differences in μδ values between pairs of catalogues and analyzed the results to characterize the μδ errors for the four catalogues with a special focus on our IL catalogue. The standard errors of μδ for IL stars observed over more than 20 years are mostly smaller than or equal to the Hipparcos errors, and close to the accuracy level of the EOC‐2 (EOC‐3, EOC‐4) and the new Hipparcos. The resulting investigations of errors of differences of μδ, show that all four catalogues have relatively small random and systematic errors which are close to each other meaning that the corresponding μδ values have a high accuracy. Our sample also contains detected double and multiple stars for which the effects of the orbital and proper motions are difficult to separate. The differences of μδ values for these stars generally exceed those obtained for single stars. Also, these discrepancies could be attributed to effect of possible, still unrecognized, astrometric binaries. These investigations about the proper motions and double stars are in line with the activity of the IAU Working Group on Astrometry by Small Ground‐Based Telescopes. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution of solar‐type stellar winds
Authors: Suzuki T.K.
Published: October 2014

By extending our self‐consistent MHD simulations for the solar wind, we study the evolution of stellar winds of solar‐type stars from early main sequence stage to red giant phase. Young solar‐type stars are active and the mass loss rates are larger by up to ∼100 times than that of the present‐day sun. We investigate how the stellar wind is affected when the magnetic field strength and fluctuation amplitude at the photosphere increase. While the mass loss rate sensitively depends on the input energy from the surface because of the global instability related to the reflection and nonlinear dissipation of Alfvén waves, it saturates at ∼100 times because most of the energy is used up for the radiative losses rather than the kinetic energy of the wind. After the end of the main sequence phase when the stellar radius expands by ∼10 times, the steady hot corona with temperature 106 K, suddenly disappears. Chromospheric materials, with hot bubbles embedded owing to thermal instability, directly stream out; the red giant wind is not a steady stream but a structured outflow. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solar irradiance variability
Authors: Solanki S.K. , Unruh Y.C.
Published: October 2014

The Sun has long been considered a constant star, to the extent that its total irradiance was termed the solar constant. It required radiometers in space to detect the small variations in solar irradiance on timescales of the solar rotation and the solar cycle. A part of the difficulty is that there are no other constant natural daytime sources to which the Sun's brightness can be compared. The discovery of solar irradiance variability rekindled a long‐running discussion on how strongly the Sun affects our climate. A non‐negligible influence is suggested by correlation studies between solar variability and climate indicators. The mechanism for solar irradiance variations that fits the observations best is that magnetic features at the solar surface, i.e. sunspots, faculae and the magnetic network, are responsible for almost all variations (although on short timescales convection and p‐mode oscillations also contribute). In spite of significant progress important questions are still open. Thus there is a debate on how strongly irradiance varies on timescales of centuries (i.e. how much darker the Sun was during the Maunder minimum than it is today). It is also not clear how the solar spectrum changes over the solar cycle. Both these questions are of fundamental importance for working out just how strongly the Sun influences our climate. Another interesting question is how solar irradiance variability compares with that of other cool dwarfs, particularly now that observations from space are available also for stars. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Furthering our knowledge of the solar neighborhood using WISE
Authors: Cushing M.C. , Kirkpatrick J.D. , Gelino C.R. , Wright E.L. , Gizis J.E. , Gomes J.I. , Leggett S.K. , Lodieu N. , Mace G.N. , Dupuy T.J.
Published: October 2014

The launch of NASA's Wide‐field Infrared Survey Explorer (WISE) in late 2009 ushered in an new era in the study of the solar neighborhood. Its mid‐infrared capabilities have proven critical to the discovery of the bulk of the coolest (Teff < 1000 K) brown dwarfs, including the new Y dwarfs, and its all‐sky coverage lends itself to searches for high proper motions stars using other infrared surveys such as the Two Micron All Sky Survey (2MASS), UKIRT Infrared Deep Sky Survey (UKIDSS), and Visible and Infrared Survey Telescope for Astronomy (VISTA) surveys. This splinter session of the 17th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun was organized to bring together researchers working with WISE data to both identify brown dwarfs and characterize their properties. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐thermal processes in coronae and beyond
Authors: Poppenhaeger K. , Günther H. M. , Beiersdorfer P. , Brickhouse N. S. , Carter J. A. , Hudson H. S. , Kowalski A. , Lalitha S. , Miceli M. , Wolk S. J.
Published: October 2014

This contribution summarizes the splinter session “Non‐thermal processes in coronae and beyond” held at the Cool Stars 17 workshop in Barcelona in 2012. It covers new developments in high energy non‐thermal effects in the Earth's exosphere, solar and stellar flares, the diffuse emission in star forming regions and reviews the state and the challenges of the underlying atomic databases. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
M dwarf stars in the light of (future) exoplanet searches
Authors: Rojas‐Ayala B. , Hilton E.J. , Mann A.W. , Lépine S. , Gaidos E. , Bonfils X. , Helling Ch. , Henry T.J. , Rogers L. A. , von Braun K. , Youdin A.
Published: October 2014

We present a brief overview of a splinter session on M dwarf stars as planet hosts that was organized as part of the Cool Stars 17 conference. The session was devoted to reviewing our current knowledge of M dwarf stars and exoplanets in order to prepare for current and future exoplanet searches focusing in low mass stars. We review the observational and theoretical challenges to characterize M dwarf stars and the importance of accurate fundamental parameters for the proper characterization of their exoplanets and our understanding on planet formation. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The kinematics of very low mass dwarfs: Splinter session summary
Authors: Burgasser A.J. , Faherty J.K. , Schmidt S. , West A.A. , Zapatero Osorio M.R. , Pineda J.S. , Burningham B. , Nicholls C. , Sanderson R. , Shkolnik E. , Rodriguez D. , Riedel A. , Joergens V.
Published: October 2014

Kinematic investigations are being increasingly deployed in studies of the lowest mass stars and brown dwarfs to investigate their origins, characterize their atmospheres, and examine the evolution of their physical parameters. This article summarizes the contributions made at the “Kinematics of Very Low Mass Dwarfs” splinter session. Results discussed include analysis of kinematic distributions of M, L, and T dwarfs; theoretical tools for interpreting these distributions; identifications of very low mass halo dwarfs and wide companions to nearby stars; radial velocity variability among young and very cool brown dwarfs; and the search and identification of M dwarfs in young moving groups. A summary of discussion points at the conclusion of the splinter sesseion is also presented. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)