bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of a Designed Poly(trimethylene carbonate) Microvascular Network by Stereolithography
Authors: Schüller‐Ravoo Sigrid , Zant Erwin , Feijen Jan , Grijpma Dirk W.
Published: October 2014

Designed flexible and elastic network structures are prepared by stereolitho­graphy using a photo‐crosslinkable resin based on a poly(trimethylene carbonate) (PTMC) macromer with a molecular weight of 3150 g/mol. Physical properties and the compatibility with human umbilical vein endothelial cells (HUVECs) are evaluated. The hydrophobic networks are found to be flexible and elastic, with an E modulus of 7.9 ± 0.1 MPa, a tensile strength of 3.5 ± 0.1 MPa and an elongation at break of 76.7 ± 0.7%. HUVECs attach and proliferate well on the surfaces of the built structures. A three‐dimensional microvascular network is designed to serve as a perfusable scaffold for tissue engineering. In the design, 5 generations of open channels each branch into 4 smaller channels yielding a microvascular region with a high density of capillaries. The overall cross‐­sectional area through which medium or blood can be perfused remains constant. These structures would ensure efficient nourishment of cells in a large volume of tissue. Built by stereolithography using the PTMC resin, the smallest channels of these structures have square cross‐sectional areas, with inner widths of approximately 224 μm and wall thicknesses of approximately 152 μm. The channels are open, allowing water to perfuse the scaffold at 0.279 ± 0.006 mL/s at 80 mmHg and 0.335 ± 0.009 mL/s at 120 mmHg.
Bias, Fallacies & Decision Errors–Processing Information: Sights, Sounds and Framing
Authors: Creo Robert A.
Published: October 2014

The Master Mediator addresses in a series of columns the psychological factors and cognitive bias that may affect dispute resolution. Recent columns have explored the seminal work of Professor Daniel Kahneman in identifying two cognitive modes: “System 1,” which is fast, instinctive and emotional, and “System 2,” which is slower, more deliberative, and more logical. Cognitive Bias is the tendency to make incorrect judgments based on erroneous presuppositions. It is a default to the System 1, with the brain processing information quickly to reach a decision or to act, without the filter and reflection of System 2. According to Professor Max Bazerman, it arises when “a heuristic is inappropriately applied by an individual in reaching a decision” (see box).
Artificial Multienzyme Supramolecular Device: Highly Ordered Self‐Assembly of Oligomeric Enzymes In Vitro and In Vivo
Authors: Gao Xin , Yang Shuai , Zhao Chengcheng , Ren Yuhong , Wei Dongzhi
Published: October 2014

A strategy for scaffold‐free self‐assembly of multiple oligomeric enzymes was developed by exploiting enzyme oligomerization and protein–protein interaction properties, and was tested both in vitro and in vivo. Octameric leucine dehydrogenase and dimeric formate dehydrogenase were fused to a PDZ (PSD95/Dlg1/zo‐1) domain and its ligand, respectively. The fusion proteins self‐assembled into extended supramolecular interaction networks. Scanning‐electron and atomic‐force microscopy showed that the assemblies assumed two‐dimensional layer‐like structures. A fluorescence complementation assay indicated that the assemblies were localized to the poles of cells. Moreover, both in vitro and in vivo assemblies showed higher NAD(H) recycling efficiency and structural stability than did unassembled structures when applied to a coenzyme recycling system. This work provides a novel method for developing artificial multienzyme supramolecular devices and for compartmentalizing metabolic enzyme cascades in living cells.
The Structure and Stability of Magic Carbon Clusters Observed in Graphene Chemical Vapor Deposition Growth on Ru(0001) and Rh(111) Surfaces
Authors: Gao Junfeng , Ding Feng
Published: October 2014

To improve the atomically controlled growth of graphene by chemical vapor deposition (CVD), understanding the evolution from various carbon species to a graphene nucleus on various catalyst surfaces is essential. Experimentally, an ultrastable carbon cluster on Ru(0001) and Rh(111) surfaces was observed, while its structure and formation process were still under debate. Using ab initio calculations and kinetic analyses, we disclose a specific type of carbon cluster, composed of a C21 core and a few dangling C atoms, which is exceptional stable in a size range from 21 to 27 C atoms. The most stable one of them, an isomer of C24 characterized by three dangling C atoms attached to the C21 core (denoted as C21‐3C), is the most promising candidate of the experimental observation. The ultrastability of C21‐3C originates from both the stable core and the appropriate passivation of the dangling carbon atoms by the catalyst surface.
Synthesis of Square‐Planar Aluminum(III) Complexes
Authors: Thompson Emily J. , Myers Thomas W. , Berben Louise A.
Published: October 2014

The synthesis of two four‐coordinate and square planar (SP) complexes of aluminum(III) is presented. Reaction of a phenyl‐substituted bis(imino)pyridine ligand that is reduced by two electrons, Na2(PhI2P2−), with AlCl3 afforded five‐coordinate [(PhI2P2−)Al(THF)Cl] (1). Square‐planar [(PhI2P2−)AlCl] (2) was obtained by performing the same reaction in diethyl ether followed by lyphilization of 2 from benzene. The four‐coordinate geometry index for 2, τ4, is 0.22, where 0 would be a perfectly square‐planar molecule. The analogous aluminum hydride complex, [(PhI2P2−)AlH] (3), is also square‐planar, and was characterized crystallographically and has τ4=0.13. Both 2 and 3 are Lewis acidic and bind 2,6‐lutidine.
Ruthenium–Porphyrin‐Catalyzed Diastereoselective Intramolecular Alkyl Carbene Insertion into CH Bonds of Alkyl Diazomethanes Generated In Situ from N‐Tosylhydrazones
Authors: Reddy Annapureddy Rajasekar , Zhou Cong‐Ying , Guo Zhen , Wei Jinhu , Che Chi‐Ming
Published: October 2014

With a ruthenium–porphyrin catalyst, alkyl diazomethanes generated in situ from N‐tosylhydrazones efficiently underwent intramolecular C(sp3)H insertion of an alkyl carbene to give substituted tetrahydrofurans and pyrrolidines in up to 99 % yield and with up to 99:1 cis selectivity. The reaction displays good tolerance of many functionalities, and the procedure is simple without the need for slow addition with a syringe pump. From a synthetic point of view, the CH insertion of N‐tosylhydrazones can be viewed as reductive coupling between a CO bond and a CH bond to form a new CC bond, since N‐tosylhydrazones can be readily prepared from carbonyl compounds. This reaction was successfully applied in a concise synthesis of (±)‐pseudoheliotridane.
Differential Sensing of MAP Kinases Using SOX‐Peptides
Authors: Zamora‐Olivares Diana , Kaoud Tamer S. , Jose Jiney , Ellington Andrew , Dalby Kevin N. , Anslyn Eric V.
Published: October 2014

Five SOX peptides are used to classify the MAPK groups and isoforms thereof using chemometrics. The score plots show excellent classification and accuracy, while support vector machine analysis leads to the quantification of ERK and an ERK inhibitor concentration in kinase mixtures. Examination of the loading plots reveals cross‐reactivity among the peptides, and some unexpected surprises.
Lewis Base Catalyzed Aerobic Oxidative Intermolecular Azide–Zwitterion Cycloaddition
Authors: Li Wenjun , Wang Jian
Published: October 2014

The discovery of a novel aerobic oxidative intermolecular azide–zwitterion reaction catalyzed by an organocatalyst is presented. It is demonstrated that the merger of the Lewis base 1,8‐diazabicyclo[5.4.0]undec‐7‐ene and electron‐deficient olefins generates reactive zwitterion intermediates, which readily participate in cycloaddition reactions with an array of azides, thus providing facile entry to fully or highly substituted 1,2,3‐triazole frameworks. The reaction features an excellent substrate scope, and the products are obtained with high yields and excellent regioselectivities. It is demonstrated that some of these products can be transformed into pharmaceutically important agents. In addition to the experimental results, a detailed mechanistic survey is also provided, including MS studies rationalizing the origin of regioselective control.
Construction of a Highly Distorted Benzene Ring in a Double Helicene
Authors: Hashimoto Sigma , Nakatsuka Soichiro , Nakamura Masaharu , Hatakeyama Takuji
Published: October 2014

A P‐fused double helicene consisting of a highly distorted benzene ring, with a bending angle of 23°, has been synthesized by a tandem intramolecular phospha‐Friedel–Crafts reaction. Despite the distortion and reduced aromaticity, the double helicene shows thermal and chemical stability. These are important features that make these compounds attractive for applications as a new C2‐symmetric bisphosphine ligand. The simple strategy proposed in this work can be used to prepare a diverse range of distorted molecules.
Pseudokontaktverschiebungen lokalisieren Eisen(III) in der zweikernigen Metallo‐β‐Laktamase IMP‐1
Authors: Carruthers Thomas J. , Carr Paul D. , Loh Choy‐Theng , Jackson Colin J. , Otting Gottfried
Published: October 2014

Heterozweikernige Metalloenzyme bilden eine bedeutende Klasse von Metalloproteinen, bei denen jedoch die Bestimmung der Positionen der Metallionen schwierig sein kann. Hier beschreiben wir ein neues NMR‐Verfahren, das Pseudokontaktverschiebungen (PCS) nutzt, um die Position von Metallionen ohne Annahmen über die koordinierenden Liganden zu ermitteln. Die Methode wird anhand des zweikernigen [FeZn]‐Komplexes von IMP‐1 beschrieben. IMP‐1 ist ein Prototyp der Metallo‐β‐Laktamasen (MβL), die Resistenz gegen β‐Laktam‐Antibiotika bewirken. Eine versuchte Einkristall‐Röntgenstrukturanalyse wurde durch teilweise Oxidation des Proteins während der Kristallisation beeinträchtigt. Mit [GaZn]‐IMP‐1 als diamagnetischer Referenz ermittelten die PCSs eindeutig die Eisen‐Bindungsstelle in frischen Proben von [FeZn]‐IMP‐1, obwohl die beiden Metallzentren weniger als 3.8 Å auseinander liegen und das Eisen als High‐Spin‐Fe3+ vorliegt, welches nur kleine PCSs erzeugt. [FeZn]‐MβLs könnten bedeutende pharmazeutische Zielproteine darstellen, da [FeZn]‐IMP‐1 enzymatisch aktiv ist und schon bei geringen Konzentrationen an Fe3+ auftritt.
A Fully Synthetic Four‐Component Antitumor Vaccine Consisting of a Mucin Glycopeptide Antigen Combined with Three Different T‐Helper‐Cell Epitopes
Authors: Palitzsch Björn , Hartmann Sebastian , Stergiou Natascha , Glaffig Markus , Schmitt Edgar , Kunz Horst
Published: October 2014

In a new concept of fully synthetic vaccines, the role of T‐helper cells is emphasized. Here, a synthetic antitumor vaccine consisting of a diglycosylated tumor‐associated MUC1 glycopeptide as the B‐cell epitope was covalently cross‐linked with three different T‐helper‐cell epitopes via squaric acid ligation of two linear (glyco)peptides. In mice this four‐component vaccine administered without external immune‐stimulating promoters elicit titers of MUC1‐specific antibodies that were about eight times higher than those induced by a vaccine containing only one T‐helper‐cell epitope. The promising results indicate that multiple activation of different T‐helper cells is useful for applications in which increased immunogenicity is required. In personalized medicine, in particular, this flexible construction of a vaccine can serve as a role model, for example, when T‐helper‐cell epitopes are needed that match human leukocyte antigens (HLA) in different patients.
Sulfamic acid heterogenized on functionalized magnetic Fe3O4 nanoparticles with diaminoglyoxime as a green, efficient and reusable catalyst for one‐pot synthesis of substituted pyrroles in aqueous phase
Authors: Veisi Hojat , Mohammadi Pourya , Gholami Javad
Published: October 2014

Surface functionalization of magnetic nanoparticles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. We have conveniently loaded sulfonic acid groups on amino‐functionalized Fe3O4 nanoparticles affording sulfamic acid‐functionalized magnetic Fe3O4 nanoparticles (MNPs/DAG‐SO3H) as an active and stable magnetically separable acidic nanocatalyst, which was characterized using X‐ray diffraction, Fourier transform infrared and energy‐dispersive X‐ray spectroscopies, scanning and transmission electron microscopies, vibrating sample magnetometry and elemental analysis. The catalytic activity of MNPs/DAG‐SO3H was probed through one‐pot synthesis of N‐substituted pyrroles from γ‐diketones and primary amines in aqueous phase at room temperature. The heterogeneous catalyst could be recovered easily by applying an external magnet device and reused many times without significant loss of its catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.
Photocatalysis of ethanol oxidation by tetrachloroferrate(III) supported on Dowex 2‐X8
Authors: Schembri Laura , Hoggard Patrick E.
Published: October 2014

FeCl4− heterogenized on a Dowex 2‐X8 anion exchange resin catalyzes the photooxidation of ethanol to acetaldehyde under visible and near‐UV irradiation (>345 nm). The rate of reaction is proportional to the oxygen partial pressure up to 1 atm. Oxidation is suggested to occur through the formation of 1‐hydroxyethylhydroperoxide, initiated by the photodissociation of a chlorine atom. The hydroperoxide re‐oxidizes the iron(II) species, both the oxidation and reduction steps producing acetaldehyde. This mechanism is consistent with the increases in yield with ethanol concentration in ethanol–toluene mixtures towards an asymptotic limit. Copyright © 2014 John Wiley & Sons, Ltd.
Ghosts of the coast: global extinction risk and conservation of sawfishes
Authors: Dulvy Nicholas K. , Davidson Lindsay N. K. , Kyne Peter M. , Simpfendorfer Colin A. , Harrison Lucy R. , Carlson John K. , Fordham Sonja V.
Published: October 2014

Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata, largetooth sawfish Pristis pristis, and green sawfish Pristis zijsron); two are Endangered (narrow sawfish Anoxypristis cuspidata, and dwarf sawfish Pristis clavata).

Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth‐studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats.

Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in <20% of its former range. Globally, sawfishes are now entirely absent from 20 countries; 43 countries have lost at least one species.

Sawfishes are legally protected, to some degree, in 16 of the 90 range states. These safeguards encompass, on average, 81% of their Extant distribution; however, the quality and breadth of protection varies dramatically across countries and species. Smalltooth sawfish currently has the least amount of such coverage of only half (49%) of Extant distribution.

The global conservation strategy specifies actions to protect sawfish and their habitats. Such actions are urgently warranted to avoid global extinction and to restore robust populations for the benefit of coastal ecosystem function and biodiversity.

© 2014 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd.
Decreased Bacterial Diversity Characterizes the Altered Gut Microbiota in Patients With Psoriatic Arthritis, Resembling Dysbiosis in Inflammatory Bowel Disease
Authors: Scher Jose U. , Ubeda Carles , Artacho Alejandro , Attur Mukundan , Isaac Sandrine , Reddy Soumya M. , Marmon Shoshana , Neimann Andrea , Brusca Samuel , Patel Tejas , Manasson Julia , Pamer Eric G. , Littman Dan R. , Abramson Steven B.
Published: October 2014

Objective

To characterize the diversity and taxonomic relative abundance of the gut microbiota in patients with never‐treated, recent‐onset psoriatic arthritis (PsA).

Methods

High‐throughput 16S ribosomal RNA pyrosequencing was utilized to compare the community composition of gut microbiota in patients with PsA (n = 16), patients with psoriasis of the skin (n = 15), and healthy, matched control subjects (n = 17). Samples were further assessed for the presence and levels of fecal and serum secretory IgA (sIgA), proinflammatory proteins, and fatty acids.

Results

The gut microbiota observed in patients with PsA and patients with skin psoriasis was less diverse when compared to that in healthy controls. This could be attributed to the reduced presence of several taxa. Samples from both patient groups showed a relative decrease in abundance of Coprococcus species, while samples from PsA patients were also characterized by a significant reduction in Akkermansia, Ruminococcus, and Pseudobutyrivibrio. Supernatants of fecal samples from PsA patients revealed an increase in sIgA levels and decrease in RANKL levels. Analysis of fatty acids revealed low fecal quantities of hexanoate and heptanoate in both patients with PsA and patients with psoriasis.

Conclusion

Patients with PsA and patients with skin psoriasis had a lower relative abundance of multiple intestinal bacteria. Although some genera were concomitantly decreased in both conditions, PsA samples had a lower abundance of reportedly beneficial taxa. This gut microbiota profile in PsA was similar to that previously described in patients with inflammatory bowel disease and was associated with changes in specific inflammatory proteins unique to this group, and distinct from that in patients with skin psoriasis and healthy controls. Thus, the role of the gut microbiome in the continuum of psoriasis–PsA pathogenesis and the associated immune response merits further study.
Head to head: The role of academic competition in undergraduate anatomical education
Authors: Van Nuland Sonya E. , Roach Victoria A. , Wilson Timothy D. , Belliveau Daniel J.
Published: October 2014

Competition is a key element in many educational games and is often adopted by educators in an effort to motivate and excite their students. Yet, the use of academic competition in educational institutions remains the subject of much debate. Opponents argue that academic competition causes an increase in student anxiety and divides their attention. However, if the contexts of academic competition are defined, could the inclusion of a game‐like competition in a university course be a viable and beneficial method of engaging students? Students (n = 67) were recruited from an undergraduate human anatomy course at Western University. Using a crossover design, students were exposed to a competitive tournament either at the time of their first term test or second term test. The anatomical knowledge of participating students was assessed prior to the start of the study using a baseline anatomy test. Following treatment with an online competitive anatomy tournament, student's term test grades and final course grades were analyzed. Both the second term test scores (F(2,64) = 3.743, P = 0.029) and overall course grades (F(2,64) = 3.356, P = 0.041) were found to be significantly different (P < 0.05) for individuals in the competitive group when compared to their non‐competing peers. As suggested by the literature where organized competition in the classroom correlates to improved academic performance, this study uncovered significant results pertaining to increased academic performance resulting from participating in tournament‐based competition. In light of these positive results, further exploration of the effects of academic competition on student performance across age brackets and disciplines is warranted. Anat Sci Educ 8: 404–412. © 2014 American Association of Anatomists.
Multifunctional Carbon Nanohorn Complexes for Cancer Treatment
Authors: Chechetka Svetlana A. , Pichon Benoit , Zhang Minfang , Yudasaka Masako , Bégin‐Colin Sylvie , Bianco Alberto , Miyako Eijiro
Published: October 2014

Multifunctional carbon nanohorn (CNH) complexes were synthesized using oxidized CNH, magnetite (MAG) nanoparticles, and polyethyleneimine (PEI). The ferromagnetic MAG nanoparticles were loaded onto CNH (MAG‐CNH) using iron(II) acetate and subsequent heat treatment. Chemical functionalization of the MAG‐CNH complexes with PEI improved their water‐dispersibility and allowed further conjugation with a fluorophore. The application of an external magnetic field significantly intensified the targeted vectorization of CNH complexes into human cervical cancer (HeLa) cells. Following cell uptake, laser irradiation of the cells showed a significant enhancement in the photothermal effects of CNHs leading to cell death. We have confirmed that the photothermal properties and ferromagnetic characteristics of CNH complexes show efficient cell elimination. The present study is an essential step toward the development of an innovative cancer therapy and a highly sensitive detection of cancer cells at the single‐cell level.
Robust Optimal Disturbance Observer Design for the Non‐Minimum Phase System
Authors: Wang Lu , Su Jianbo
Published: October 2014

In this paper, a design strategy of robust disturbance observer is proposed systematically for stable non‐minimum phase systems. This strategy synthesizes the internal and robust stability, relative order and mixed sensitivity design requirements together to establish the optimization function. The optimal solution is obtained by standard H∞ control theory under the condition of guarantying the presented requirements. Simulation results of a rotary mechanical system show the effectiveness of the proposed strategy.
Monitoring change point for diffusion parameter based on discretely observed sample from stochastic differential equation models
Authors: Lee Sangyeol , Guo Meihui
Published: October 2014

Stochastic differential equation (SDE) models are useful in describing complex dynamical systems in science and engineering. In this study, we consider a monitoring procedure for an early detection of dispersion parameter change in SDE models. The proposed scheme provides a useful diagnostic analysis for phase I retrospective study and develops a flexible and effective control chart for phase II prospective monitoring. A standardized control chart is constructed, and a bootstrap method is used to estimate the mean and variance of the monitoring statistic. The control limit is obtained as an upper percentile of the maximum value of a standard Wiener process. The proposed procedure appears to have a manageable computational complexity for online implementation and also to be effective in detecting changes. We also investigate the performance of the exponentially weighted mean squared control charts for the continuous SDE processes. A simulation method is used to study the empirical sizes and the average run length characteristics of the proposed scheme, which also demonstrates the effectiveness of our method. Finally, we provide an empirical example for illustration. Copyright © 2014 John Wiley & Sons, Ltd.
On random age and remaining lifetime for populations of items
Authors: Finkelstein Maxim , Vaupel James
Published: October 2014

We consider items that are incepted into operation having already a random (initial) age and define the corresponding remaining lifetime. We show that these lifetimes are identically distributed when the age distribution is equal to the equilibrium distribution of the renewal theory. Then we develop the population studies approach to the problem and generalize the setting in terms of stationary and stable populations of items. We obtain new stochastic comparisons for the corresponding population ages and remaining lifetimes that can be useful in applications. Copyright © 2014 John Wiley & Sons, Ltd.
Detection of transient high frequency optical oscillations of the flare star YZ CMin
Authors: Contadakis M.E. , Avgoloupis S.J. , Seiradakis J.H.
Published: October 2014

In this paper we present the results of the analysis of the B ‐light curve for the flares of the red dwarf YZ CMin (dM4.5e), which were observed on February of 2002, with the help of the 30‐inch Cassegrain telescope of the Stephanion Observatory, Greece. Discrete Fourier Transform analysis and the use of the Brownian Walk noise enable us to estimate the proper random noise and detect possible weak transient optical oscillations. Our results indicate that: (1) Transient high frequency oscillations occur during the flare event and during the quiet‐star phase as well. (2) The observed frequencies range between 0.0083 Hz (period 2 min) and 0.3 Hz (period 3 s) is not rigorously bounded. The phenomenon is most pronounced during the flare state. (3) During the flare state: (a) Oscillations with period 2 to 1.5 min, 60 s, 11 s, 7.5 s, and 4 s appear around the maximum light state and persist during the whole flare state, (b) from the flare maximum phase on, a progressive increase of oscillations with periods 30 s, 20 s down to 4.0 s is markedly indicated, and (c) at the end of the flare only the oscillation of the pre‐flare state do remain. Our observations are consistent with the phenomenology of impulsively exited oscillations on a coronal magnetic loop and subsequent chromospheric heating by electronic flux at the foot of the loop or/and by soft X‐ray coronal emission. Our observation give evidence that more than one impulsive events may occur in the course of an observed flare (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Environmental dependence of the presence of active galactic nuclei (AGNs) in the volume‐limited Main galaxy samples of SDSS DR6
Authors: Deng X.‐F. , Xin Y. , Wu P. , Jiang P. , Ding Y.‐P. , Qi X.‐P.
Published: October 2014

Using two volume‐limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 6 (SDSS DR6) above and below the value of M∗︁r, we have explored the environmental dependence of the AGN fraction. It is found that the fraction of AGNs declines substantially with increasing local density in the luminous volume‐limited sample, but in the faint volume‐limited sample this change is very weak. We also note that the presence of AGNs is not correlated with the stellar mass (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MUCHFUSS – Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS
Authors: Geier S. , Schaffenroth V. , Hirsch H. , Tillich A. , Heber U. , Maxted P.F.L. , Østensen R.H. , Barlow B.N. , O'Toole S.J. , Kupfer T. , Marsh T. , Gänsicke B. , Napiwotzki R. , Cordes O. , Müller S. , Classen L. , Ziegerer E. , Drechsel H.
Published: October 2014

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions (white dwarfs with masses M > 1.0 M⊙, neutron stars or black holes). The existence of such systems is predicted by binary evolution calculations and some candidate systems have been found. We identified ≃1100 hot subdwarf stars from the Sloan Digital Sky Survey (SDSS). Stars with high velocities have been reobserved and individual SDSS spectra have been analysed. About 70 radial velocity variable subdwarfs have been selected as good candidates for follow‐up time resolved spectroscopy to derive orbital parameters and photometric follow‐up to search for features like eclipses in the light curves. Up to now we found nine close binary sdBs with short orbital periods ranging from ≃0.07 d to 1.5 d. Two of them are eclipsing binaries with companions that are most likely of substellar nature (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Debris disks as seen by Herschel/DUNES
Authors: Löhne T. , Eiroa C. , Augereau J.‐C. , Ertel S. , Marshall J.P. , Mora A. , Absil O. , Stapelfeldt K. , Thébault P. , Bayo A. , del Burgo C. , Danchi W. , Krivov A.V. , Lebreton J. , Letawe G. , Magain P. , Maldonado J. , Montesinos B. , Pilbratt G.L. , White G.J. , Wolf S.
Published: October 2014

The far‐infrared excesses produced by debris disks are common features of stellar systems. These disks are thought to contain solids ranging from micron‐sized dust to planetesimals. Naturally, their formation and evolution are linked to those of potential planets. With this motivation, the Herschel open time key programme DUNES (DUst around NEarby Stars) aims at further characterising known debris disks and discovering new ones in the regime explored by the Herschel space observatory. On the one hand, in their survey of 133 nearby FGK stars, DUNES discovered a class of extremely cold and faint debris disks, different from well‐known disks such as the one around Vega in that their inferred typical grain sizes are rather large, indicating low dynamical excitation and low collision rates. On the other hand, for the more massive disk around the sun‐like star HD 207129, well‐resolved PACS images confirmed the ring‐liked structure seen in HST images and provided valuable information for an in‐depth study and benchmark for models. Employing both models for power‐law fitting and collisional evolution we found the disk around HD 207129 to feature low collision rates and large grains, as well. Transport by means of Poynting‐Robertson drag likely plays a role in replenishing the dust seen closer to the star, inside of the ring. The inner edge is therefore rather smooth and the contribution from the extended halo of barely bound grains is small. Both slowly self‐stirring and planetary perturbations could potentially have formed and shaped this disk (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The promises of Gaia
Authors: Prusti T.
Published: October 2014

Gaia is an ESA mission performing astrometry, photometry and spectroscopy of about one billion objects in our Milky Way galaxy and beyond. The extent and content of the Gaia Catalogues will enable major progress to be made in many fields of galactic and stellar astronomy. The prime industrial contractor, EADS Astrium, Toulouse, is manufacturing the spacecraft and its payload for launch in 2013. Parallel to the space segment development the ground segment is getting ready as well. The Mission Operations Centre in Darmstadt, the Science Operations Centre in Madrid and the Gaia Data Processing and Analysis Consortium having members in many institutes across Europe are all tackling the challenges imposed by the high scientific requirements of the mission. The Gaia observing principles, overall status and scientific performances will be outlined (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Galactic thin and thick disk
Authors: Steinmetz M.
Published: October 2014

The ongoing large spectroscopic surveys of the Milky Way such as SEGUE and RAVE have enabled us to take a fresh look at the structure of the Galactic thin and thick disks, and how their structure fits within the framework of structure formation via hierarchical clustering. In this article I will summarize some recent results mainly based in the RAVE survey with respect to the structure of the Galactic disks, their possible origin as well as indications of substructure and asymmetries (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Torun catalogue of 6.7 GHz methanol masers
Authors: Szymczak M. , Wolak P. , Bartkiewicz A. , Borkowski K.M.
Published: October 2014

We report the observations of 289 methanol maser sources at 6.7 GHz obtained over a two month period with the Torun 32 m telescope. The data form a catalogue of all objects north of δ = –22° brighter than 7.5 Jy in the peak emission. The positions of sub‐arcsecond accuracy are updated for 76 % of the objects. We find that about one third of the sources show changes in the peak fluxes by a factor of two or more on time scales of 8.5–9.5 years (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Composite spectra: XVIII HR 6497, a triple system containing a baffling double secondary
Authors: Griffin R.E.M. , Griffin R.F.
Published: October 2014

We present a full description of, and parameters for, the component stars in the triple‐lined composite‐spectrum system HR 6497. Both the outer and the inner orbits have already been computed with fair accuracy, but the improved orbits resulting from this new analysis have precisions that are up to an order of magnitude tighter. By applying the proven technique of spectral subtraction to a large sample of new, high‐quality spectra we separate the spectra of the inner pair cleanly for the first time, and show that it has characteristics which cannot be explained at all easily by conventional models. Since the inner pair are separated by only 4 times their own radii, we expect their rotations to be synchronized to their orbital revolution, or close to 28 km/s, but in fact they have almost no visible rotation at all. The Mg II line at λ 4481 Å, itself a close doublet with a separation of 0.2 Å, is clearly resolved in the spectra of both components of the inner system. Such resolution is extremely rare in our experience, and we are unable to suggest a satisfactory explanation for it (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Principles of high‐dimensional data visualization in astronomy
Authors: Goodman A.A.
Published: October 2014

Astronomical researchers often think of analysis and visualization as separate tasks. In the case of high‐dimensional data sets, though, interactive exploratory data visualization can give far more insight than an approach where data processing and statistical analysis are followed, rather than accompanied, by visualization. This paper attempts to charts a course toward “linked view” systems, where multiple views of high‐dimensional data sets update live as a researcher selects, highlights, or otherwise manipulates, one of several open views. For example, imagine a researcher looking at a 3D volume visualization of simulated or observed data, and simultaneously viewing statistical displays of the data set's properties (such as an x ‐y plot of temperature vs. velocity, or a histogram of vorticities). Then, imagine that when the researcher selects an interesting group of points in any one of these displays, that the same points become a highlighted subset in all other open displays. Selections can be graphical or algorithmic, and they can be combined, and saved. For tabular (ASCII) data, this kind of analysis has long been possible, even though it has been under‐used in astronomy. The bigger issue for astronomy and other “high‐dimensional” fields, though, is that no extant system allows for full integration of images and data cubes within a linked‐view environment. The paper concludes its history and analysis of the present situation with suggestions that look toward cooperatively‐developed open‐source modular software as a way to create an evolving, flexible, high‐dimensional, linked‐view visualization environment useful in astro‐physical research (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Collisions of comets and meteoroids: The post Stardust‐NExT discussion
Authors: Gronkowski P. , Wesolowski M.
Published: October 2014

The paper considers results of collisions between comets and meteoroids. We re‐discuss the five different approaches to estimate the sizes of holes created during such collisions. The results of the Deep Impact and the Stardust‐NExT missions to comet 9P/Temple 1 are applied to the estimation of these methods. We use the observed amount of ejected mass, the jump of brightness of the comet 9P/Tempel 1 as well as the diameter of the excavated crater. In the paper the simple way of estimation of impact consequences by use of the conception of the fragmentation energy of comet is also discussed. The numerical calculations were carried out for reasonable assumed values of a large range of cometary characteristics. The main conclusion of this paper confirms a general presumption that the main factor which determines the size of the impact crater on the comet 9P/Tempel 1 is the kinetic energy of impactor and strength or fragmentation energy of cometary material. In the considered case the gravitation of a comet has a minor meaning (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Dwarf project: Eclipsing binaries – precise clocks to discover exoplanets
Authors: Pribulla T. , Vaňko M. , Ammler‐von Eiff M. , Andreev M. , Aslantürk A. , Awadalla N. , Baluďansky D. , Bonanno A. , Božić H. , Catanzaro G. , Çelik L. , Christopoulou P.E. , Covino E. , Cusano F. , Dimitrov D. , Dubovský P. , Eigmueller P. , Esmer E.M. , Frasca A. , Hambálek Ľ. , Hanna M. , Hanslmeier A. , Kalomeni B. , Kjurkchieva D.P. , Krushevska V. , Kudzej I. , Kundra E. , Kuznyetsova Yu. , Lee J.W. , Leitzinger M. , Maciejewski G. , Moldovan D. , Morais M.H.M. , Mugrauer M. , Neuhäuser R. , Niedzielski A. , Odert P. , Ohlert J. , Özavcı İ. , Papageorgiou A. , Parimucha Š. , Poddaný S. , Pop A. , Raetz M. , Raetz S. , Romanyuk Ya. , Ruždjak D. , Schulz J. , Şenavcı H.V. , Srdoc G. , Szalai T. , Székely P. , Sudar D. , Tezcan C.T. , Törün M.E. , Turcu V. , Vince O. , Zejda M.
Published: October 2014

We present a new observational campaign, Dwarf, aimed at detection of circumbinary extrasolar planets using the timing of the minima of low‐mass eclipsing binaries. The observations will be performed within an extensive network of relatively small to medium‐size telescopes with apertures of ∼20‐200 cm. The starting sample of the objects to be monitored contains (i) low‐mass eclipsing binaries with M and K components, (ii) short‐period binaries with a sdB or sdO component, and (iii) post‐common‐envelope systems containing a WD, which enable to determine minima with high precision. Since the amplitude of the timing signal increases with the orbital period of an invisible third component, the timescale of the project is long, at least 5‐10 years. The paper gives simple formulas to estimate the suitability of individual eclipsing binaries for the circumbinary planet detection. Intrinsic variability of the binaries (photospheric spots, flares, pulsation etc.) limiting the accuracy of the minima timing is also discussed. The manuscript also describes the best observing strategy and methods to detect cyclic timing variability in the minima times indicating the presence of circumbinary planets. First test observations of the selected targets are presented (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gregor@night: The future high‐resolution stellar spectrograph for the GREGOR solar telescope
Authors: Strassmeier K.G. , Ilyin I.V. , Woche M. , Granzer T. , Weber M. , Weingrill J. , Bauer S.‐M. , Popow E. , Denker C. , Schmidt W. , von der Lühe O. , Berdyugina S. , Collados M. , Koubsky P. , Hackman T. , Mantere M.J.
Published: October 2014

We describe the future night‐time spectrograph for the GREGOR solar telescope and present its science core projects. The spectrograph provides a 3‐pixel resolution of up to R = 87 000 in 45 échelle orders covering the wavelength range 390‐900 nm with three grating settings. An iodine cell can be used for high‐precision radial velocity work in the 500‐630 nm range. The operation of the spectrograph and the telescope will be fully automated without the presence of humans during night‐time and will be based on the successful STELLA control system. Future upgrades include a second optical camera for even higher spectral resolution, a Stokes‐V polarimeter and a link to the laser‐frequency comb at the Vacuum Tower Telescope. The night‐time core projects are a study of the angular‐momentum evolution of “The Sun in Time” and a continuation of our long‐term Doppler imaging of active stars (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A retrospective of the GREGOR solar telescope in scientific literature
Authors: Denker C. , von der Lühe O. , Feller A. , Arlt K. , Balthasar H. , Bauer S.‐M. , Bello González N. , Berkefeld Th. , Caligari P. , Collados M. , Fischer A. , Granzer T. , Hahn T. , Halbgewachs C. , Heidecke F. , Hofmann A. , Kentischer T. , Klvaňa M. , Kneer F. , Lagg A. , Nicklas H. , Popow E. , Puschmann K.G. , Rendtel J. , Schmidt D. , Schmidt W. , Sobotka M. , Solanki S.K. , Soltau D. , Staude J. , Strassmeier K.G. , Volkmer R. , Waldmann T. , Wiehr E. , Wittmann A.D. , Woche M.
Published: October 2014

In this review, we look back upon the literature, which had the GREGOR solar telescope project as its subject including science cases, telescope subsystems, and post‐focus instruments. The articles date back to the year 2000, when the initial concepts for a new solar telescope on Tenerife were first presented at scientific meetings. This comprehensive bibliography contains literature until the year 2012, i.e., the final stages of commissioning and science verification. Taking stock of the various publications in peer‐reviewed journals and conference proceedings also provides the “historical” context for the reference articles in this special issue of Astronomische Nachrichten/Astronomical Notes (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparing the GREGOR solar telescope for night‐time use: Deriving a pointing model
Authors: Granzer T. , Halbgewachs C. , Volkmer R. , Soltau D.
Published: October 2014

We report on the results of a dedicated campaign to derive a pointing model for the GREGOR solar telescope which took place in December 2011. Two main goals were in the focus of this campaign: first to prove the aptness of the GREGOR solar telescope for night‐time, unattended operations and second to derive some qualitative measure of the amount of misalignment in the optical and mechanical parts of the telescope. In the final version, a root‐mean‐square deviation (RMSD) of 1.6″ for the azimuth model and an RMSD of 2.3″ in the elevation model could be achieved (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The GREGOR telescope control system
Authors: Halbgewachs C. , Caligari P. , Glogowski K. , Heidecke F. , Knobloch M. , Mustedanagic M. , Volkmer R. , Waldmann T.A.
Published: October 2014

This article describes the architecture of the new GREGOR telescope and its instrument control system. A short summary is given on the communication structure between instruments and other devices during observation. Because of its importance to all instruments the main functions of the telescope control system are described in detail (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The GREGOR Broad‐Band Imager
Authors: von der Lühe O. , Volkmer R. , Kentischer T.J. , Geißler R.
Published: October 2014

The design and characteristics of the Broad‐Band Imager (BBI) of GREGOR are described. BBI covers the visible spectral range with two cameras simultaneously for a large field and with critical sampling at 390 nm, and it includes a mode for observing the pupil in a Foucault configuration. Samples of first‐light observations are shown (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GRIS: The GREGOR Infrared Spectrograph
Authors: Collados M. , López R. , Páez E. , Hernández E. , Reyes M. , Calcines A. , Ballesteros E. , Díaz J.J. , Denker C. , Lagg A. , Schlichenmaier R. , Schmidt W. , Solanki S.K. , Strassmeier K.G. , von der Lühe O. , Volkmer R.
Published: October 2014

This paper describes the main characteristics of GRIS (GREGOR Infrared Spectrograph), the grating spectrograph installed in the recently inaugurated (May 2012) 1.5‐meter GREGOR telescope located at the Observatorio del Teide in Tenerife. The spectrograph has a standard Czerny‐Turner configuration with parabolic collimator and camera mirrors that belong to the same conic surface. Although nothing prevents its use at visible wavelengths, the spectrograph will be initially used in combination with the infrared detector of the Tenerife Infrared Polarimeter (TIP‐II) in standard spectroscopic mode as well as for spectropolarimetric measurements (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The GREGOR adaptive optics system
Authors: Berkefeld Th. , Schmidt D. , Soltau D. , von der Lühe O. , Heidecke F.
Published: October 2014

The new 1.5‐m German solar telescope GREGOR at the Observatorio del Teide, Tenerife, is equipped with an integrated adaptive optics system. Although partly still in the commissioning phase, the system is already being used used for most science observations. It is designed to provide diffraction‐limited observations in the visible‐light regime for seeing better than 1.2″. We describe the AO system including the optical design, software, wavefront reconstruction, and performance (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanical design of the solar telescope GREGOR
Authors: Volkmer R. , Eisenträger P. , Emde P. , Fischer A. , von der Lühe O. , Nicklas H. , Soltau D. , Schmidt W. , Weis U.
Published: October 2014

The mechanical structure of the GREGOR telescope was installed at the Observatorio del Teide, Tenerife, in 2004. New concepts for mounting and cooling of the 1.5‐meter primary mirror were introduced. GREGOR is an open telescope, therefore the dome is completely open during observations to allow for air flushing through the open, but stiff telescope structure. Backside cooling system of the primary mirror keeps the mirror surface close to ambient temperature to prevent mirror seeing. The large collecting area of the primary mirror results in high energy density at the field stop at the prime focus of the primary which needs to be removed. The optical elements are supported by precision alignment systems and should provide a stable solar image at the optical lab. The coudé train can be evacuated and serves as a natural barrier between the outer environmental conditions and the air‐conditioned optical laboratory with its sensitive scientific instrumentation. The telescope was successfully commissioned and will start its nominal operation during 2013 (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three‐dimensional magnetohydrodynamic simulations of M‐dwarf chromospheres
Authors: Wedemeyer S. , Ludwig H.‐G. , Steiner O.
Published: October 2014

We present first results from three‐dimensional radiation magnetohydrodynamic simulations of M‐type dwarf stars with CO5BOLD. The local models include the top of the convection zone, the photosphere, and the chromosphere. The results are illustrated for models with an effective temperature of 3240 K and a gravitational acceleration of log g = 4.5, which represent analogues of AD Leo. The models have different initial magnetic field strengths and field topologies. This first generation of models demonstrates that the atmospheres of M dwarfs are highly dynamic and intermittent. Magnetic fields and propagating shock waves produce a complicated fine‐structure, which is clearly visible in synthetic intensity maps in the core of the Ca II K spectral line and also at millimeter wavelengths. The dynamic small‐scale pattern cannot be described by means of one‐dimensional models, which has important implications for the construction of semi‐empirical model atmospheres and thus for the interpretation of observations in general. Detailed three‐dimensional numerical simulations are valuable in this respect. Furthermore, such models facilitate the analysis of small‐scale processes, which cannot be observed on stars but nevertheless might be essential for understanding M‐dwarf atmospheres and their activity. An example are so‐called “magnetic tornadoes”, which have recently been found on the Sun and are presented here in M‐dwarf models for the first time. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)