bluuebunny/crossref_metadata_2025_split huggingface dataset:
A hydrodynamical study of multiple‐shell planetary nebulae
Authors: Schönberner D. , Jacob R. , Lehmann H. , Hildebrandt G. , Steffen M. , Zwanzig A. , Sandin C. , Corradi R.L.M. 
Published: October 2014

AbstractWe present the result of a study on the expansion properties and internal kinematics of round/elliptical planetary nebulae of the Milky Way disk, the halo, and of the globular cluster M 15. The purpose of this study is to considerably enlarge the small sample of nebulae with precisely determined expansion properties (Schönberner et al. 2005b). To this aim, we selected a representative sample of objects with different evolutionary stages and metallicities and conducted highresolution ´echelle spectroscopy. In most cases we succeeded in detecting the weak signals from the outer nebular shell which are attached to the main line emission from the bright nebular rim. Next to the measurement of the motion of the rim gas by decomposition of the main line components into Gaussians, we were able to measure separately, for most objects for the first time, the gas velocity immediately behind the leading shock of the shell, i.e. the post‐shock velocity. We more than doubled the number of objects for which the velocities of both rim and shell are known and confirm that the overall expansion of planetary nebulae is accelerating with time. There are, however, differences between the expansion behaviour of the shell and the rim: The post‐shock velocity is starting at values as low as around 20 km s–1 for the youngest nebulae, just above the AGB wind velocity of ∼ 10–15 km s–1, and is reaching values of about 40 km s–1 for the nebulae around hotter central stars. Contrarily, the rim matter is at first decelerated below the typical AGB‐wind velocity and remains at about 5–10 km s–1 for a while until finally a typical flow velocity of up to 30 km s–1 is reached. This observed distinct velocity evolution of both rim and shell is explained by radiation‐hydrodynamics simulations, at least qualitatively: It is due to the ever changing stellar radiation field and wind‐wind interaction together with the varying density profile ahead of the leading shock during the progress of evolution. The wind‐wind interaction works on the rim dynamics while the radiation field and upstream density gradient is responsible for the shell dynamics. Because of these time‐dependent boundary conditions, a planetary nebula will never evolve into a simple self‐similar expansion. Also the metal‐poor objects behave as theory predicts: The post‐shock velocities are higher and the rim flow velocities are equal or even lower compared to disk objects at similar evolutionary stage. The old nebula around low‐luminosity central stars contained in our sample expand still fast and are dominated by reionisation. We detected, for the first time, in some objects an asymmetric expansion behaviour: The relative expansions between rim and shell appear to be different for the receding and approaching parts of the nebular envelope. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
TASTE IV: Refining ephemeris and orbital parameters for HAT‐P‐20b and WASP‐1b
Authors: Granata V. , Nascimbeni V. , Piotto G. , Bedin L. R. , Borsato L. , Cunial A. , Damasso M. , Malavolta L. 
Published: October 2014

AbstractWe present four new light curves of the transiting exoplanets WASP‐1b and HAT‐P‐20b, observed within the TASTE (The Asiago Search for Transit timing variations of Exoplanets) project. We re‐analyzed light curves from the literature in a homogeneous way, calculating a refined ephemeris and orbital‐physical parameters for both objects. WASP‐1b does not show any significant Transit Timing Variation signal at the 120 s level. As for HAT‐P‐20b, we detected a deviation from our re‐estimated linear ephemeris that could be ascribed to the presence of a perturber or, more probably, to a previously unnoticed high level of stellar activity. The rotational period of HAT‐P‐20 A that we obtained from archival data (Prot ≃ 14.5 d), combined with its optical variability and strong emission of Ca ii H & K lines, is consistent with a young stellar age (<1 Gyr) and support the hypothesis that stellar activity may be responsible of the measured deviations of the transit times. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Seven years photometry of the W UMa‐type eclipsing binary V2612 Oph
Authors: Özdarcan O. , Taş G. 
Published: October 2014

AbstractWe present the first long‐term Johnson UBVR observations and comprehensive photometric analysis of the W UMa‐type eclipsing binary V2612 Oph. Observations in the time interval between 2003 and 2009 enabled us to reveal the seasonal and long‐term variations of the light curve. Hence, we found that the mean brightness level of the light curve shows a variation with a period of 6.7 years. Maximum and minimum brightness levels of the light curve exhibit a variation from year to year which we attribute to a solar‐like activity. The O – C variation of eclipse timings of the system shows a decreasing parabolic trend and reveals a period decrease at a rate of P = 6.27×10‐7 day yr‐1 with an additional low‐amplitude sinusoidal variation that has a similar period as the long‐term brightness variations. Our light curve analysis shows that the system is a W‐subtype W UMa eclipsing binary. We calculated masses and radii of the primary and secondary components as M1 = 1.28 M⊙, M2 = 0.37 M⊙ and R1 = 1.31 R⊙, R2 = 0.75 R⊙, respectively. The derived absolute photometric parameters allow us to calculate a distance of 140 pc, which confirms that the system is a foreground star in the sky field of the Galactic open cluster NGC 6633. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamical evolution of two associated galactic bars
Authors: Garzón F. , López‐Corredoira M. 
Published: October 2014

AbstractWe study the dynamical interactions of mass systems in equilibrium under their own gravity that mutually exert and ex‐perience gravitational forces. The method we employ is to model the dynamical evolution of two isolated bars, hosted within the same galactic system, under their mutual gravitational interaction. In this study, we present an analytical treatment of the secular evolution of two bars that oscillate with respect to one another. Two cases of interaction, with and without geometrical deformation, are discussed. In the latter case, the bars are described as modified Jacobi ellipsoids. These triaxial systems are formed by a rotating fluid mass in gravitational equilibrium with its own rotational velocity and the gravitational field of the other bar. The governing equation for the variation of their relative angular separation is then numerically integrated, which also provides the time evolution of the geometrical parameters of the bodies. The case of rigid, non‐deformable, bars produces in some cases an oscillatory motion in the bodies similar to that of a harmonic oscillator. For the other case, a deformable rotating body that can be represented by a modified Jacobi ellipsoid under the influence of an exterior massive body will change its rotational velocity to escape from the attracting body, just as if the gravitational torque exerted by the exterior body were of opposite sign. Instead, the exchange of angular momentum will cause the Jacobian body to modify its geometry by enlarging its long axis, located in the plane of rotation, thus decreasing its axial ratios. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Relationship between low and high frequencies in the δ Scuti star KIC 9764965
Authors: Rostopchina A. , Breger M. 
Published: October 2014

AbstractTwo years of Kepler spacecraft data of the δ Sct/γ Dor star KIC 9764965 revealed 67 statistically significant frequencies from 0.45 to 59.17 c d–1 (0.005 to 0.685 mHz). The 19 low frequencies do not show equidistant period spacing predicted for gravity modes of successive radial order. We note a favored frequency spacing of 2.053 c d–1 that appears in both the low‐frequency (gravity mode) region and high‐frequency (pressure mode) regions. The value of this frequency spacing also occurs as a dominant low frequency and in a high‐frequency triplet. A peak at exactly twice the value of the 2.053 cd–1 mode is shown not to be a Fourier harmonic of the low‐frequency peak due to a different amplitude variability. This behavior is also seen in other δ Sct stars. The test for resonant mode coupling between low and high frequencies could not be carried out due to the small amplitudes of the peaks, making it difficult to separate the parent and child modes. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Delphi survey to identify topics to be addressed at the initial follow-up consultation after oesophageal cancer surgery
Authors: Jacobs M , Henselmans I , Macefield R C , Blencowe N S , Smets E M A , de Haes J C J M , Sprangers M A G , Blazeby J M , van Berge Henegouwen M I 
Published: October 2014

AbstractBackgroundThere is no consensus among patients and healthcare professionals (HCPs) on the topics that need to be addressed after oesophageal cancer surgery. The aim of this study was to identify these topics, using a two-round Delphi survey.MethodsIn round 1, patients and HCPs (surgeons, dieticians, nurses) were invited to rate the importance of 49 topics. The proportion of panellists that considered a topic to be of low, moderate or high importance was then calculated for each of these two groups. Based on these proportions and the i.q.r., topics were categorized as: ‘consensus to be included’, ‘consensus to be excluded’ and ‘no consensus’. Only topics in the first category were included in the second round. In round 2, panellists were provided with individual and group feedback. To be included in the final list, topics had to meet criteria for consensus and stability.ResultsThere were 108 patients and 77 HCPs in the round 2 analyses. In general, patients and HCPs considered the same topics important. The final list included 23 topics and revealed that it was most important to address: cancer removed/lymph nodes, the new oesophagus, eating and drinking, surgery, alarming new complaints and the recovery period.ConclusionThe study provides surgeons with a list of topics selected by patients and HCPs that may be addressed systematically at the initial follow-up consultation after oesophageal cancer surgery.
Induction of cortical plasticity for reciprocal muscles by paired associative stimulation
Authors: Suzuki Makoto , Kirimoto Hikari , Sugawara Kazuhiro , Watanabe Makoto , Shimizu Shinobu , Ishizaka Ikuyo , Yamada Sumio , Matsunaga Atsuhiko , Fukuda Michinari , Onishi Hideaki 
Published: October 2014

AbstractBackgroundPaired associative stimulation (PAS) is widely used to induce plasticity in the human motor cortex. Although reciprocal inhibition of antagonist muscles plays a fundamental role in human movements, change in cortical circuits for reciprocal muscles by PAS is unknown.MethodsWe investigated change in cortical plasticity for reciprocal muscles during PAS. PAS consisted of 200 pairs of peripheral electric stimulation of the right median nerve at the wrist at a frequency of 0.25 Hz followed by transcranial magnetic stimulation of the left M1 at the midpoint between the center of gravities of the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles. Measures of motor cortical excitability included resting motor threshold (RMT), GABAA‐mediated short‐interval intracortical inhibition (SICI), and GABAB‐mediated long‐interval intracortical inhibition (LICI).ResultsMotor evoked potential amplitude‐conditioned LICI for the FCR muscle was significantly decreased after PAS (P = 0.020), whereas that for the ECR muscle was significantly increased (P = 0.033). Changes in RMT and SICI for the FCR and ECR muscles were not significantly different before and after PAS. Corticospinal excitability for both reciprocal muscles was increased during PAS, but GABAB‐mediated cortical inhibitory functions for the agonist and antagonist muscles were reciprocally altered after PAS.ConclusionThese results implied that the cortical excitability for reciprocal muscles including GABAB‐ergic inhibitory systems within human M1 could be differently altered by PAS.
A High‐Throughput Assay for Arylamine Halogenation Based on a Peroxidase‐Mediated Quinone–Amine Coupling with Applications in the Screening of Enzymatic Halogenations
Authors: Hosford Joseph , Shepherd Sarah A. , Micklefield Jason , Wong Lu Shin 
Published: October 2014

AbstractArylhalides are important building blocks in many fine chemicals, pharmaceuticals and agrochemicals, and there has been increasing interest in the development of more “green” halogenation methods based on enzyme catalysis. However, the screening and development of new enzymes for biohalogenation has been hampered by a lack of high‐throughput screening methods. Described herein is the development of a colorimetric assay for detecting both chemical and enzymatic arylamine halogenation reactions in an aqueous environment. The assay is based on the unique UV/Vis spectrum created by the formation of an ortho‐benzoquinone‐amine adduct, which is produced by the peroxidase‐catalysed benzoquinone generation, followed by Michael addition of either a halogenated or non‐halogenated arylamine. This assay is sensitive, rapid and amenable to high‐throughput screening platforms. We have also shown this assay to be easily coupled to a flavin‐dependent halogenase, which currently lacks any convenient colorimetric assay, in a “one‐pot” workflow.
The Action of Peroxyl Radicals, Powerful Deleterious Reagents, Explains Why Neither Cholesterol Nor Saturated Fatty Acids Cause Atherogenesis and Age‐Related Diseases
Authors: Spiteller Gerhard , Afzal Mohammad 
Published: October 2014

AbstractCells respond to alterations in their membrane structure by activating hydrolytic enzymes. Thus, polyunsaturated fatty acids (PUFAs) are liberated. Free PUFAs react with molecular oxygen to give lipid hydroperoxide molecules (LOOHs). In case of severe cell injury, this physiological reaction switches to the generation of lipid peroxide radicals (LOO.). These radicals can attack nearly all biomolecules such as lipids, carbohydrates, proteins, nucleic acids and enzymes, impairing their biological functions. Identical cell responses are triggered by manipulation of food, for example, heating/grilling and particularly homogenization, representing cell injury. Cholesterol as well as diets rich in saturated fat have been postulated to accelerate the risk of atherosclerosis while food rich in unsaturated fatty acids has been claimed to lower this risk. However, the fact is that LOO. radicals generated from PUFAs can oxidize cholesterol to toxic cholesterol oxides, simulating a reduction in cholesterol level. In this review it is shown how active LOO. radicals interact with biomolecules at a speed transcending usual molecule–molecule reactions by several orders of magnitude. Here, it is explained how functional groups are fundamentally transformed by an attack of LOO. with an obliteration of essential biomolecules leading to pathological conditions. A serious reconsideration of the health and diet guidelines is required.
HOMO Stabilisation in π‐Extended Dibenzotetrathiafulvalene Derivatives for Their Application in Organic Field‐Effect Transistors
Authors: Geng Yan , Pfattner Raphael , Campos Antonio , Wang Wei , Jeannin Olivier , Hauser Jürg , Puigdollers Joaquim , Bromley Stefan T. , Decurtins Silvio , Veciana Jaume , Rovira Concepció , Mas‐Torrent Marta , Liu Shi‐Xia 
Published: October 2014

AbstractThree new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB‐TTF) central core and a 2,1,3‐chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB‐TTF, have been synthesised as active materials for organic field‐effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron‐withdrawing 2,1,3‐chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution‐processed single‐crystal transistors exhibit high performance with a hole mobility up to 0.04 cm2 V−1 s−1 as well as good ambient stability.
Reactivity of Liquid Ammonia Solutions of the Zintl Phase K12Sn17 towards Mesitylcopper(I) and Phosphinegold(I) Chloride
Authors: Benda Christian B. , Waibel Markus , Köchner Tobias , Fässler Thomas F. 
Published: October 2014

AbstractTo gain more insight into the reactivity of intermetalloid clusters, the reactivity of the Zintl phase K12Sn17, which contains [Sn4]4− and [Sn9]4− cluster anions, was investigated. The reaction of K12Sn17 with gold(I) phosphine chloride yielded K7[(η2‐Sn4)Au(η2‐Sn4)](NH3)16 (1) and K17[(η2‐Sn4)Au(η2‐Sn4)]2(NH2)3(NH3)52 (2), which both contain the anion [(Sn4)Au(Sn4)]7− (1 a) that consists of two [Sn4]4− tetrahedra linked through a central gold atom. Anion 1 a represents the first binary AuSn polyanion. From this reaction, the solvate structure [K([2.2.2]crypt)]3K[Sn9](NH3)18 (3; [2.2.2]crypt=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) was also obtained. In the analogous reaction of mesitylcopper with K12Sn17 in the presence of [18]crown‐6 in liquid ammonia, crystals of the composition [K([18]crown‐6)]2[K([18]crown‐6)(MesH)(NH3)][Cu@Sn9](thf) (4) were isolated ([18]crown‐6=1,4,7,10,13,16‐hexaoxacyclooctadiene, MesH=mesitylene, thf=tetrahydrofuran) and featured a [Cu@Sn9]3− cluster. A similar reaction with [2.2.2]crypt as a sequestering agent led to the formation of crystals of [K[2.2.2]crypt][MesCuMes] (5). The cocrystallization of mesitylene in 4 and the presence of [MesCuMes]− (5 a) in 5 provides strong evidence that the migration of a bare Cu atom into an Sn9 anion takes place through the release of a Mes− anion from mesitylcopper, which either migrates to another mesitylcopper to form 5 a or is subsequently protonated to give MesH.
Lead Structures for New Antibacterials: Stereocontrolled Synthesis of a Bioactive Muraymycin Analogue
Authors: Spork Anatol P. , Büschleb Martin , Ries Oliver , Wiegmann Daniel , Boettcher Stefan , Mihalyi Agnes , Bugg Timothy D. H. , Ducho Christian 
Published: October 2014

AbstractNaturally occurring muraymycin nucleoside antibiotics represent a promising class of novel antibacterial agents. The structural complexity suggests the investigation of simplified analogues as potential lead structures, which can then be further optimized towards highly potent antimicrobials. Herein we report studies on muraymycin‐derived potential lead structures lacking an aminoribose motif found in most naturally occurring muraymycins. We have identified a 5′‐defunctionalized motif to be ideal in terms of stability and chemical accessibility and have synthesized a full‐length muraymycin analogue based on this structure using a novel fully stereocontrolled route. The obtained 5′‐deoxy analogue of the natural product muraymycin C4 showed good inhibitory properties towards the bacterial target protein MraY, sufficient pharmacokinetic stability and no cytotoxicity against human cells, thus making it a promising lead for antibacterial drug development.
3‐Deazaneplanocin A and Neplanocin A Analogues and Their Effects on Apoptotic Cell Death
Authors: Tam Eric K. W. , Nguyen Tuan Minh , Lim Cheryl Z. H. , Lee Puay Leng , Li Zhimei , Jiang Xia , Santhanakrishnan Sridhar , Tan Tiong Wei , Goh Yi Ling , Wong Sze Yue , Yang Haiyan , Ong Esther H. Q. , Hill Jeffrey , Yu Qiang , Chai Christina L. L. 
Published: October 2014

Abstract3‐Deazaneplanocin A (DzNep) is a potential epigenetic drug for the treatment of various cancers. DzNep has been reported to deplete histone methylations, including oncogenic EZH2 complex, giving rise to epigenetic modifications that reactivate many silenced tumor suppressors in cancer cells. Despite its promise as an anticancer drug, little is known about the structure–activity relationships of DzNep in the context of epigenetic modifications and apoptosis induction. In this study, a number of analogues of DzNep were examined for DzNep‐like ability to induce synergistic apoptosis in cancer cells in combination with trichostatin A, a known histone deacetylase (HDAC) inhibitor. The structure–activity relationship data thus obtained provide valuable information on the structural requirements for biological activity. The studies identified three compounds that show similar activities to DzNep. Two of these compounds show good pharmacokinetics and safety profiles. Attempts to correlate the observed synergistic apoptotic activities with measured S‐adenosylhomocysteine hydrolase (SAHH) inhibitory activities suggest that the apoptotic activity of DzNep might not be directly due to its inhibition of SAHH.
Organotopic organization of the primary Infrared Sensitive Nucleus (LTTD) in the western diamondback rattlesnake (Crotalus atrox)
Authors: Kohl Tobias , Bothe Maximilian S. , Luksch Harald , Straka Hans , Westhoff Guido 
Published: October 2014

ABSTRACTPit vipers (Crotalinae) have a specific sensory system that detects infrared radiation with bilateral pit organs in the upper jaw. Each pit organ consists of a thin membrane, innervated by three trigeminal nerve branches that project to a specific nucleus in the dorsal hindbrain. The known topographic organization of infrared signals in the optic tectum prompted us to test the implementation of spatiotopically aligned sensory maps through hierarchical neuronal levels from the peripheral epithelium to the first central site in the hindbrain, the nucleus of the lateral descending trigeminal tract (LTTD). The spatial organization of the anatomical connections was revealed in a novel in vitro whole‐brain preparation of the western diamondback rattlesnake (Crotalus atrox) that allowed specific application of multiple neuronal tracers to identified pit‐organ‐supplying trigeminal nerve branches. After adequate survival times, the entire peripheral and central projections of fibers within the pit membrane and the LTTD became visible. This approach revealed a morphological partition of the pit membrane into three well‐defined sensory areas with largely separated innervations by the three main branches. The peripheral segregation of infrared afferents in the sensory epithelium was matched by a differential termination of the afferents within different areas of the LTTD, with little overlap. This result demonstrates a topographic organizational principle of the snake infrared system that is implemented by maintaining spatially aligned representations of environmental infrared cues on the sensory epithelium through specific neuronal projections at the level of the first central processing stage, comparable to the visual system. J. Comp. Neurol. 522:3943–3959, 2014. © 2014 Wiley Periodicals, Inc.