bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulated Light Curves of Multiperiodic Stars
Authors: Benkő József M. , Szabó Róbert , Paparó Margit
Published: April 2012

We modelled the light curves of modulated multiperiodically pulsating stars by a simple double-mode pulsation with combined amplitude and frequency modulations. The synthetic light curves and their spectra show similar features to those we found and discussed for monoperiodic stars. Comparing the synthetic light curves and their spectra with the observed ones helps us to classify the modulations and to distinguish between long-period modulation (Blazhko effect) and the other types of amplitude and/or period changes.
Fermi LAT Flare Advocate Activity
Authors: Ciprini Stefano , Gasparrini Dario , Bastieri Denis
Published: April 2012

The Fermi Flare Advocate (also known as Gamma-ray Sky Watcher, FA-GSW) service provides a daily quick-look analysis and review of the high-energy gamma-ray sky seen by the Fermi Gamma-ray Space Telescope. The duty offers alerts for potentially new gamma-ray sources, interesting transients and flares. A weekly digest containing the highlights about the GeV gamma-ray sky is published in the web-based Fermi Sky Blog. During the first 3 years of all-sky survey, more than 150 Astronomical Telegrams, several alerts to the TeV Cherenkov telescopes, and targets of opportunity to Swift and other observatories, were realized. That increased the rate of simultaneous multi-frequency observing campaigns and the level of international cooperation. Many gamma-ray flares from blazars (such as extraordinary outbursts of 3C 454.3, intense flares of PKS 1510-089, 4C 21.35, PKS 1830-211, AO 0235+164, PKS 1502+106, 3C 279, 3C 273, PKS 1622-253), short/long flux duty cycles, unidentified transients near the Galactic plane (like J0910-5041, J0109+6134, the Galactic center region), flares associated with Galactic sources (like the Crab nebula, the nova V407 Cyg, the microquasar Cyg X-3), emission of the quiet and active sun, were observed by Fermi and communicated by FA-GSWs.
Inverse Mapping of Pulsar Magnetospheres: Optical Emission Comes From 300 km Above the Surface
Authors: de Búrca Diarmaid , O'Connor Padraig , McDonald John , Shearer Andy
Published: April 2012

In order to determine the emission height of the optical photons from pulsars we present an inverse mapping approach, which is directly constrained by empirical data. The model discussed is for the case of the Crab pulsar. Our method, which uses the optical Stokes parameters, determines the most likely geometry for emission including the magnetic-field inclination angle (α), the observer's line-of-sight angle (χ) and emission height. We discuss the computational implementation of the approach, and the physical assumptions made. We find that the most likely emission altitude is at 20% of the light-cylinder radius above the stellar surface in the open field region.
The Catalina Real-time Transient Survey
Authors: Drake A. J. , Djorgovski S. G. , Mahabal A. , Prieto J. L. , Beshore E. , Graham M. J. , Catalan M. , Larson S. , Christensen E. , Donalek C. , Williams R.
Published: April 2012

The Catalina Real-time Transient Survey (CRTS) currently covers 33,000 deg2 of the sky in search of transient astrophysical events, with time base-lines ranging from 10 minutes to ~7 years. Data provided by the Catalina Sky Survey provide an unequalled base-line against which > 4,000 unique optical transient events have been discovered and openly published in real-time. Here we highlight some of the discoveries of CRTS.
Searching for Periodic Variables in the EROS-2 Database
Authors: Dubath P. , Lecoeur I. , Rimoldini L. , Süveges M. , Blomme J. , López M. , Sarro L. M. , De Ridder J. , Cuypers J. , Guy L. , Nienartowicz K. , Jan A. , Beck M. , Mowlavi N. , Ordóñez-Blanco D. , Marquette J. B. , Beaulieu J. P. , Tisserand P. , Lesquoy É. , Eyer L.
Published: April 2012

We started a systematic search for periodic variable-star candidates in the EROS-2 database in the context of preparatory work for the Gaia satellite mission. The goal is to evaluate different classification tools and strategies, and to identify a large sample of variable candidates. In this paper we present the results of an assessment study of a three-step identification and classification process. In the study we took a sample of about 80,000 stars from one of the LMC EROS fields.
Testing the Standard Model of Active Galactic Nuclei through Quasar Variability
Authors: Ederoclite Alessandro , Polednikova Jana , Cepa Jordi , de Diego Onsurbe José Antonio , González-Serrano Ignacio
Published: April 2012

The standard model of Active Galactic Nuclei (AGNs) predicts that Type 2 AGNs and Type 1 AGNs only differ in the orientation of a dust torus, which does or does not allow one to observe the central region. If the model is correct, the time-scales and the amplitudes of observed temporal variations should be different between obscured and unobscured objects. In order to test this hypothesis, we started a multi-wavelength (BRIJKs) monitoring campaign of a sample of quasars of both types. Here we present the data and preliminary results of that project.
Time-Domain Studies of Gravitationally Lensed Quasars
Authors: Goicoechea Luis J. , Shalyapin Vyacheslav N.
Published: April 2012

We present an overview and current results of an ongoing optical/NIR monitoring of seven gravitationally-lensed quasars (GLQs) with the 2-m Liverpool Robotic Telescope. The photometric data from the first seven years (2005–2011) of this programme are leading to high-quality light curves, which in turn are being used as key tools for different standard and novel studies. While brightness records of non-lensed distant quasars may contain unrecognized extrinsic variations, one can disentangle intrinsic from extrinsic signals in certain GLQs. Thus, some GLQs in our sample allow us to assess their extrinsic and intrinsic variations; we then discuss the origin of both kinds of fluctuations. We also demonstrate the usefulness of GLQ time-domain data for obtaining successful reverberation maps of the inner regions of accretion disks around distant supermassive black holes, and for estimating the redshifts of distant lensing galaxies.
Hottest Superfluid and Superconductor in the Universe: Lessons from the Cooling of the Cassiopeia A Neutron Star
Authors: Ho Wynn C. G. , Heinke Craig O. , Patnaude Daniel J. , Shternin Peter S. , Yakovlev Dmitry G.
Published: April 2012

The cooling rate of young neutron stars gives direct insight into their internal makeup. Using Chandra observations of the 330-year-old Cassiopeia A supernova remnant, we find that the temperature of the youngest-known neutron star in the Galaxy has declined by 4% over the last 10 years. The decline is explained naturally by superconductivity and superfluidity of the protons and neutrons in the stellar core. The protons became superconducting early in the life of the star and suppressed the early cooling rate; the neutron star thus remained hot before the (recent) onset of neutron superfluidity. Once the neutrons became superfluid, the Cooper pair-formation process produced a splash of neutrino emission which accelerated the cooling and resulted in the observed rapid temperature decline. This is the first time a young neutron star has been seen to cool in real time, and is the first direct evidence, from cooling observations, of superfluidity and superconductivity in the core of neutron stars.
What To Do with Sparkers?
Authors: Keane E. F. , Stappers B. W. , Kramer M. , Lyne A. G.
Published: April 2012

In 2007, the discovery of the so-called “Lorimer Burst” was announced—a single radio pulse that was so dispersed that it could only have originated outside our Galaxy. The apparently unique event, together with the large inferred distance (a redshift z ~0.2 is required to explain its high dispersion) implies a very high luminosity. Suggested progenitors include a supernova, a binary neutron-star merger, and a black-hole annihilation event. Crude estimates of the rates of such events predict that many such bursts should already be detectable in archived pulsar-survey data, and has led to detailed searches which have had some success.
Towards Improving the Prospects for Coordinated Gravitational-Wave and Electromagnetic Observations
Authors: Mandel Ilya , Kelley Luke Z. , Ramirez-Ruiz Enrico
Published: April 2012

We discuss two approaches to searches for gravitational-wave (GW) and electromagnetic (EM) counterparts of binary neutron-star mergers. The first approach relies on triggering archival searches of GW detector data based on detections of EM transients. Quantitative estimates of the improvement to GW detector reach due to the increased confidence in the presence and parameters of a signal from a binary merger gained from the EM transient suggest utilizing other transients in addition to short gamma-ray bursts. The second approach involves following up GW candidates with targeted EM observations. We argue for the use of slower but optimal parameter-estimation techniques and for a more sophisticated use of astrophysical prior information, including galaxy catalogues to find preferred follow-up locations.
Statistics of Stellar Variability in Kepler Data with ARC Systematics Removal
Authors: McQuillan Amy , Aigrain Suzanne , Roberts Stephen
Published: April 2012

We investigate the variability properties of main-sequence stars in the first month of Kepler data, using a new astrophysically robust systematics correction. We find that 36% appear more variable than the Sun, and confirm the trend of increasing variability with decreasing effective temperature. We define low- and high-variability samples, with a cut at twice the level of the active Sun, and compare properties of the stars belonging to each sample. We find tentative evidence that the more active stars have lower proper motions. The frequency content of the variability shows clear evidence for periodic or quasi-periodic behaviour in 16% of stars, and highlights significant differences in the nature of variability between spectral types. Most A and F stars have short periods (< 2 days) and highly sinusoidal variability, suggestive of pulsations, whilst G, K and M stars tend to have longer periods (> 5 days, with a trend towards longer periods at later spectral types) and show a mixture of periodic and stochastic variability, indicative of activity. Finally, we use autoregressive models to characterise the stochastic component of the variability, and show that its typical amplitude and time-scale increase towards later spectral types, which we interpret as an increase in the characteristic size and life-time of active regions. Full details will be published shortly.
Variability Analysis based on POSS1/POSS2 Photometry
Authors: Mickaelian Areg M. , Sarkissian Alain , Sinamyan Parandzem K.
Published: April 2012

We introduce accurate magnitudes as combined calculations from catalogues based on accurate measurements of POSS1- and POSS2-epoch plates. The photometric accuracy of various catalogues was established, and statistical weights for each of them have been calculated. To achieve the best possible magnitudes, we used weighted averaging of data from APM, MAPS, USNO-A2.0, USNO-B1.0 (for POSS1-epoch), and USNO-B1.0 and GSC 2.3.2 (for POSS2-epoch) catalogues. The r.m.s. accuracy of magnitudes achieved for POSS1 is 0.184 in B and 0.173 mag in R, or 0.138 in B and 0.128 in R for POSS2. By adopting those new magnitudes we examined the First Byurakan Survey (FBS) of blue stellar objects for variability, and uncovered 336 probable and possible variables among 1103 objects with POSS2–POSS1 ≥ 3σ of the errors, including 161 highly probable variables. We have developed methods to control and exclude accidental errors for any survey. We compared and combined our results with those given in Northern Sky Variability Survey (NSVS) database, and obtained firm candidates for variability. By such an approach it will be possible to conduct investigations of variability for large numbers of objects.
Optical Pulsations from Isolated Neutron Stars
Authors: Mignani Roberto P.
Published: April 2012

Because they are fast rotating objects, isolated neutron stars (INS) are obvious targets for high-time-resolution observations. With the number of optical/UV/IR INSs detections now at 24, timing observations become increasingly important in INS astrophysics.
Search for Turbulent Gas through Interstellar Scintillation
Authors: Moniez M. , Ansari R. , Habibi F. , Rahvar S.
Published: April 2012

Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected when the light of remote stars crosses a Galactic—disk or halo—refractive medium such as a molecular cloud. We present the promising results of a test performed with the ESO–NTT, and consider its potential.
Optical Polarimetry of the Crab Nebula
Authors: Moran Paul , Shearer Andy , Mignani Roberto
Published: April 2012

Time-resolved polarisation measurements of pulsars provide an unique insight into the geometry of the emission regions. Hubble Space Telescope (HST) polarisation data of the Crab Nebula were obtained from the Multimission Archive at STScI (MAST). The data are composed of a series of observations of the Crab Nebula with the HST and ACS camera system taken in three different polarisation filters (0°, 60° and 120°) between 2003 August and 2005 December. Polarisation vector maps of the Nebula were produced with the polarimetry software IMPOL. The degree of polarisation (P.D.) and the position angle (P.A.) of the pulsar's integrated pulse beam were measured, and also that of the nearby Synchrotron Knot, yielding P.D. = 4.90 ± 0.33 %, P.A. = 106°.46 ± 1°.9 for the pulsar, and P.D. = 61.70 ± 0.72 %, P.A. = 126°.86 ± 0°.23 for the Synchrotron Knot. These results are consistent with those of obtained by others using INTEGRAL.
Time-Domain Astrophysics with SuperWASP
Authors: Norton A. J. ,   the SuperWASP Consortium
Published: April 2012

SuperWASP is the world's leading ground-based survey for transiting exoplanets. Its database now contains over 300 billion data points covering 30 million unique objects from 10 million images obtained over 1700 nights since 2004. In addition to having discovered 70 transiting exoplanets, SuperWASP enables long-baseline, high-cadence studies of variable stars to be performed. We summarise some of the studies already carried out, and look ahead to the prospects for studying periodic variables with varying periods. The science which is thus supported will include studies of the Blazhko effect in RR Lyræ stars, migrating starspots in rotational variables, third bodies in eclipsing binaries, and coalescing binary stars.
ARCONS: a Highly Multiplexed Superconducting UV-to-Near-IR Camera
Authors: O'Brien Kieran , Mazin Ben , McHugh Sean , Meeker Seth , Bumble Bruce
Published: April 2012

ARCONS, the Array Camera for Optical to Near-infrared Spectrophotometry, was recently commissioned at the coudé focus of the 200-inch Hale Telescope at the Palomar Observatory. At the heart of this unique instrument is a 1024-pixel Microwave Kinetic Inductance Detector (MKID), exploiting the Kinetic Inductance effect to measure the energy of the incoming photon to better than several percent. The ground-breaking instrument is lens-coupled with a pixel scale of 0″.23/pixel, each pixel recording the arrival time (< 2 μ sec) and energy of a photon (~10%) in the optical to near-IR (0.4–1.1 microns) range. The scientific objectives of the instrument include the rapid follow-up and classification of transient phenomena.
Using the Gregory-Loredo Algorithm for the Detection of Variability in the Chandra Source Catalog
Authors: Rots Arnold H.
Published: April 2012

In searching for a reliable variability indicator for Chandra X-ray event data, we implemented the Gregory-Loredo (G–L) algorithm to assess variability and to generate light curves for the Chandra Source Catalog. A test was performed on 118 sources detected in a single observation, spanning the intensity range 5–24,000 photons over a total observing time of 102,000 sec. We conclude that the G–L algorithm is extremely robust, yielding both a reliable variability indicator and light curves with optimal resolution, while requiring a very modest amount of CPU time. The algorithm can also work on binned data, and is capable of handling data gaps as well as variations in effective area.
On Our Multi-Wavelength Campaign of the 2011 Outburst of T Pyx
Authors: Schmidtobreick L. , Bayo A. , Momany Y. , Ivanov V. , Barria D. , Beletsky Y. , Boffin H. M. J. , Brammer G. , Carraro G. , de Wit W.-J. , Girard J. , Hau G. , Moerchen M. , Nuernberger D. , Pretorius M. , Rivinius T. , Sanchez-Janssen R. , Selman F. , Stefl S. , Yegorova I.
Published: April 2012

The well-known recurrent nova T Pyx has brightened by 7 magnitudes, starting on 2011 April 14, its first eruption since 1966. T Pyx is unique amongst recurrent novæ in being surrounded by a nebula formed of material ejected during previous eruptions. The latest eruption therefore offers the rare opportunity to observe a light echo sweeping through the existing shell, and a new one forming. The sudden exposure of the existing shell to high-energy light is expected to result in a change of the dust morphology as well as in the part destruction of molecules. We observe this process in the near- and mid-IR during several epochs using ESO's VLT instruments Sinfoni, Visir and Isaac. Unfortunately, in the data analysed so far we only have a tentative detection in Brα from the shell, so might in the end have to be content with upper limits for the emission from the various molecular bands and ionised lines.
Multi-wave Monitoring of the Gravitational Lensed Quasar Q0957+561
Authors: Shalyapin Vyacheslav N. , Goicoechea Luis J. , Gil-Merino Rodrigo
Published: April 2012

We present X-ray (Chandra), ultraviolet (Swift/UVOT; U band) and optical-infrared (Liverpool Telescope; griz bands) continuum light curves of Q0957+561 observed in the first half of 2010. A cross-correlation analysis of the light curves shows that the U-band fluctuation leads the other variations at higher and lower energies. The study constrains the geometry of the continuum emission regions in a distant radio-loud AGN for the first time. We note that our work opens a new window in echo-mapping of high-z AGNs with the use of lensed quasars, since the variability of some of the images of a given multiply-imaged quasar can be predicted in advance, provided there is a modest optical follow-up of the system.
Source Detection with Interferometric Datasets
Authors: Trott Cathryn M. , Wayth Randall B. , Macquart Jean-Pierre R. , Tingay Steven J.
Published: April 2012

The detection of sources in interferometric radio data typically relies on extracting information from images, formed by Fourier transform of the underlying visibility dataset, and CLEANed of contaminating sidelobes through iterative deconvolution. Variable and transient radio sources span a large range of variability timescales, and their study has the potential to enhance our knowledge of the dynamic universe. Their detection and classification involve large data rates and non-stationary PSFs, commensal observing programs and ambitious science goals, and will demand a paradigm shift in the deployment of next-generation instruments. Optimal source detection and classification in real time requires efficient and automated algorithms. On short time-scales variability can be probed with an optimal matched filter detector applied directly to the visibility dataset. This paper shows the design of such a detector, and some preliminary detection performance results.
Wide-Field Plate Database: Latest Results
Authors: Tsvetkov Milcho , Tsvetkova Katya
Published: April 2012

We present the Wide-Field Plate Database, a basic source of data and meta-data for astronomy's more than 2.4 million wide-field photographic images obtained with professional telescopes worldwide. The technology developed in Sofia for plate digitization with commercial high-quality flatbed scanners yields low-resolution digital images for quick visualization and easy online access, and optimal high-resolution ones for photometric and astrometric investigations.
The VLBA Fast Radio Transient Experiment: Progress and Early Results
Authors: Wayth Randall B. , Brisken Walter F. , Deller Adam T. , Majid Walid A. , Thompson David R. , Tingay Steven J. , Wagstaff Kiri L.
Published: April 2012

Motivated by recent discoveries of isolated, dispersed radio pulses of possible extragalactic origin, we are performing a commensal search for short-duration (ms) continuum radio pulses using the Very Long Baseline Array (VLBA). The geographically separated antennæ of the VLBA make the system robust to local RFI and allow events to be verified and localised on the sky with milli-arcsec accuracy. We report sky coverage and detection limits from the experiment to date.
Around Gaia Alerts in 20 questions
Authors: Wyrzykowski Łukasz , Hodgkin Simon
Published: April 2012

Gaia is a European Space Agency (ESA) astrometry space mission, and a successor to the ESA Hipparcos mission. Gaia's main goal is to collect high-precision astrometric data (positions, parallaxes, and proper motions) for the 1 billion brightest objects in the sky. Those data, complemented with multi-band, multi-epoch photometric and spectroscopic data observed from the same observing platform, will allow astronomers to reconstruct the formation history, structure, and evolution of the Galaxy.

Gaia will observe the whole sky for 5 years, providing a unique opportunity for the discovery of large numbers of transient and anomalous events such as supernovæ, novæ and microlensing events, GRB afterglows, fallback supernovæ, and other theoretical or unexpected phenomena. The Photometric Science Alerts team has been tasked with the early detection, classification and prompt release of anomalous sources in the Gaia data stream. In this paper we discuss the challenges we face in preparing to use Gaia to search for transient pheonomena at optical wavelengths.
Reflections on a Week in Oxford
Authors: Murphy Tara
Published: April 2012

When Bob asked me a couple of days ago to give this talk, he said it should be “pithy and wise.” When I spoke to Aris the next day he said it should be “informal and funny.” Then Elizabeth spoke to me and said it would be great if it was “controversial and challenging.” I mentioned to Aris just before dinner that I had put a talk together, and he said “Oh, you've written a talk—I thought it would be something more spontaneous!” Faced with an obviously impossible spec, I did what any reasonable programmer would do and rewrote the spec myself. So what I'm going to talk about this evening is a reflection on my week in Oxford.
Judicialversus‘natural’ selection of legal rules with an application to accident law
Authors: MICELI THOMAS J.
Published: April 2012

Law and economics scholars argue that the common law evolves toward efficiency. Invisible-hand theories suggest that the law is primarily driven by a selection process whereby inefficient laws are litigated more frequently than efficient laws, and hence are more likely to be overturned. However, the preferences of judges also necessarily affect legal change. This paper models the interaction of these two forces to evaluate the efficiency claim, and then applies the conclusions to the evolution of accident law in the United States beginning in the 19th century. Specifically, it attributes the persistence of negligence to its efficiency properties, despite its having been initially selected by judges for a different reason. The paper relates legal evolution to biological evolution by employing the concepts of natural and artificial selection, and the more recent concept of exaptation.
What is the European Medicines Agency?
Authors: Bighelli I. , Barbui C.
Published: April 2012

In Europe, new medicines are approved or rejected on the basis of the results of studies carried out by the manufacturer and submitted to the European Medicines Agency (EMA). This article briefly presents the main roles and responsibilities of the EMA and the key rules that govern the approval process. The main scientific limitations of this process are highlighted, together with some suggestions for dealing with them.
Zum Zusammenhang zwischen körperlicher Aktivität und kognitiver Leistung im höheren Erwachsenenalter
Authors: Linde Katja , Pfeffer Ines
Published: April 2012

Zusammenfassung. Bisherige Forschungsergebnisse deuten darauf hin, dass körperliche Aktivität zur Aufrechterhaltung der kognitiven Leistungsfähigkeit im Alter beiträgt. Welche Wirkmechanismen dabei eine Rolle spielen, ist noch nicht eindeutig geklärt. Ziel dieser Studie ist es, die Bedeutung der kardiovaskulären Fitness, der Kraftleistung sowie der Depressivität als Mediatoren zwischen körperlicher Aktivität und verschiedenen fluiden kognitiven Fähigkeiten im Alter unter Anwendung von Strukturgleichungsmodellen zu untersuchen. N = 208 Probanden (83 männlich) im Alter zwischen 60 und 80 Jahren wurden im Rahmen einer Querschnittserhebung untersucht. Die Ergebnisse zeigen, dass eine hohe körperliche Aktivität im Alter mit einer hohen kardiovaskulären Fitness und Kraftleistung, sowie einer geringen Depressivität einhergeht. Eine hohe kardiovaskuläre Fitness sowie eine hohe Kraftleistung gehen wiederum mit einer hohen Verarbeitungsgeschwindigkeit und einer hohen Leistung im logischen Schlussfolgern und räumlichen Vorstellen einher. Eine hohe Kraftleistung weist darüber hinaus einen positiven Zusammenhang zur verbalen Gedächtnisleistung auf. Zwischen dem Ausmaß der Depressivität und der kognitiven Leistung konnten hingegen keine Zusammenhänge nachgewiesen werden. Die Ergebnisse deuten darauf hin, dass eher Indikatoren der körperlichen Fitness als psychologische Wirkmechanismen den Zusammenhang zwischen körperlichen Aktivität und kognitiven Fähigkeiten im Alter erklären könnten. Implikationen für Forschung und Praxis werden diskutiert.
Wie wirkt sich die Teilnahme an kollegialer Beratung auf die Gesundheit aus?
Authors: Zimber Andreas , Ullrich Annette
Published: April 2012

Zusammenfassung. Die kollegiale Beratung stellt eine weitverbreitete Methode zur Weiterentwicklung arbeitsrelevanter Kompetenzen dar. Ihr potenzieller Beitrag zur individuellen Stressprävention und Gesundheitsförderung wurde bisher kaum empirisch untersucht. Ziel dieser Interventionsstudie war es, postulierte Wirkungen und Wirkprozesse auf der Grundlage arbeitspsychologischer Modelle zu überprüfen. In einer psychiatrischen Klinik wurde die kollegiale Beratung in einer fünf-monatigen Pilotphase organisationsweit eingeführt. Durchschnittlich nahmen in den Gruppen vier bis fünf Pflegekräfte etwa einmal monatlich freiwillig an von ingesamt 19 geschulten Moderatoren geleiteten Sitzungen teil. Diese Maßnahme wurde mit einer Testbatterie im Prä-Post-Design evaluiert. Von 102 Pflegemitarbeitern beteiligten sich 60 an beiden Befragungen. Von diesen nahmen 32 Personen mindestens dreimal an den Sitzungen teil (Treatment-Gruppe). Die Ergebnisse zeigen keine Effekte auf interne Ressourcen wie problemorientierte Stressbewältigung, Handlungskompetenzen und berufliche Selbstwirksamkeit. Externe Ressourcen, u.a. Entscheidungsspielraum und soziale Unterstützung, verbesserten sich in der Gesamtgruppe signifikant. Bei den gesundheitlichen Outcomes (Irritation und Burnout) zeigte sich lediglich eine signifikante Abnahme emotionaler Irritation. Zwischen der Treatment- und der Kontrollgruppe trat nur bei einer Variablen ein signifikanter Verlaufsunterschied auf. Aus der Studie werden Praxisempfehlungen für die Durchführung und Evaluation der kollegialen Beratung abgeleitet.
The dark portion of the Mediterranean Sea is a bioreactor of organic matter cycling
Authors: Luna G. M. , Bianchelli S. , Decembrini F. , De Domenico E. , Danovaro R. , Dell'Anno A.
Published: April 2012

Total prokaryotic abundance, prokaryotic heterotrophic production and enzymatic activities were investigated in epi‐, meso‐ and bathypelagic waters along a longitudinal transect covering the entire Mediterranean Sea. The prokaryotic production and enzymatic activities in deep waters were among the highest reported worldwide at similar depths, indicating that the peculiar physico‐chemical characteristics of the Mediterranean Sea, characterized by warm temperatures (typically 13°C also at abyssal depths), support high rates of organic carbon degradation and incorporation by prokaryotic assemblages. The higher trophic conditions in the epipelagic waters of the Western basin resulted in significantly higher prokaryotic production and enzymatic activities rates than in the Central‐Eastern basin. While all of the variables decreased significantly from epi‐ to meso‐ and bathypelagic waters, cell‐specific hydrolytic activity and cell‐specific carbon production significantly increased. In addition, the deep‐water layers were characterized by low half‐saturation constants (Km) of all enzymatic activities. These findings suggest that prokaryotic assemblages inhabiting the dark portion of the Mediterranean Sea are able to channel degraded carbon into biomass in a very efficient way, and that prokaryotic assemblages of the deep Mediterranean waters work as a “bioreactor” of organic matter cycling. Since prokaryotic production and enzymatic activities in deep water masses were inversely related with oxygen concentration, we hypothesize a tight link between prokaryotic metabolism and oxygen consumption. As climate change is increasing deep‐water temperatures, the predicted positive response of prokaryotic metabolism to temperature increases may accelerate oxygen depletion of deep Mediterranean waters, with cascade consequences on carbon cycling and biogeochemical processes on the entire deep basin.
Reconnection at the magnetopause of Saturn: Perspective from FTE occurrence and magnetosphere size
Authors: Lai H. R. , Wei H. Y. , Russell C. T. , Arridge C. S. , Dougherty M. K.
Published: April 2012

Flux transfer events observed at Mercury, Earth, and Jupiter are attributed to spatially and temporally limited events in which the magnetosheath and magnetospheric magnetic field become interconnected and magnetic flux is transported from the dayside to the lobes of the magnetotail. Examination of the Saturnian magnetopause at local times from 1000 to 1400 shows no evidence for this phenomenon. Nevertheless, we do find brief intervals during which the normal component of the magnetic field across the magnetopause becomes significantly enhanced for typically one to ten minutes. Magnetosheath electrons appear during these episodes of enhanced magnetic field normal components indicating that indeed the magnetosphere is connected to the magnetosheath by these magnetic bridges. To determine if this magnetic connection leads to a measurable transfer of magnetic flux from the dayside, we check the location of the magnetopause standoff distance for both northward and southward magnetosheath fields. In 71 crossings, we find no obvious dependence of the distance on the direction of the magnetosheath field, indicating that the direction of the interplanetary magnetic field is not a major factor in the determination of the location of the Saturnian magnetopause. This is unlike the position of the terrestrial magnetosphere that undergoes significant motion through reconnection with the interplanetary magnetic field.
Year‐round radiocarbon‐based source apportionment of carbonaceous aerosols at two background sites in South Asia
Authors: Sheesley Rebecca J. , Kirillova Elena , Andersson August , Kruså Martin , Praveen P. S. , Budhavant Krishnakant , Safai P. D. , Rao P. S. P. , Gustafsson Örjan
Published: April 2012

Atmospheric Brown Clouds (ABC), regional‐scale haze events, are a significant concern for both human cardiopulmonary health and regional climate impacts. In order to effectively mitigate this pollution‐based phenomenon, it is imperative to understand the magnitude, scope and source of ABC in regions such as South Asia. Two sites in S. Asia were chosen for a 15‐month field campaign focused on isotope‐based source apportionment of carbonaceous aerosols in 2008–2009. Both the Maldives Climate Observatory in Hanimaadhoo (MCOH) and a mountaintop site in Sinhagad, India (SINH) act as regionally mixed receptor sites. Annual radiocarbon‐based source apportionment for soot elemental carbon (SEC) at MCOH and SINH revealed 73 ± 6% and 59 ± 5% contribution from biomass combustion, respectively (remainder from fossil fuel). The contributions from biogenic/biomass combustion to total organic carbon were similar between MCOH and SINH (69 ± 5% and 64 ± 5, respectively). The biomass combustion contribution for SEC in the current study, especially the results from MCOH, shows good agreement with published black carbon emissions inventories for India. Geographic source assessment, including clustered back trajectory analysis and carbon contribution by source region, indicated that the highest SEC/TOC loads originated from the W. Indian coastal margin, including the coastal city of Mumbai, India. The winter dry season 14C‐based source apportionment of the BC‐tracing SEC fraction for 2006, 2008, 2009 were not statistically different (p = 0.7) and point to a near‐constant two‐thirds contribution from biomass combustion practices, including wood and other biofuels as well as burning of agricultural crop residues.
Crash testing hydrological models in contrasted climate conditions: An experiment on 216 Australian catchments
Authors: Coron L. , Andréassian V. , Perrin C. , Lerat J. , Vaze J. , Bourqui M. , Hendrickx F.
Published: April 2012

This paper investigates the actual extrapolation capacity of three hydrological models in differing climate conditions. We propose a general testing framework, in which we perform series of split‐sample tests, testing all possible combinations of calibration‐validation periods using a 10 year sliding window. This methodology, which we have called the generalized split‐sample test (GSST), provides insights into the model's transposability over time under various climatic conditions. The three conceptual rainfall‐runoff models yielded similar results over a set of 216 catchments in southeast Australia. First, we assessed the model's efficiency in validation using a criterion combining the root‐mean‐square error and bias. A relation was found between this efficiency and the changes in mean rainfall (P) but not with changes in mean potential evapotranspiration (PE) or air temperature (T). Second, we focused on average runoff volumes and found that simulation biases are greatly affected by changes in P. Calibration over a wetter (drier) climate than the validation climate leads to an overestimation (underestimation) of the mean simulated runoff. We observed different magnitudes of these models deficiencies depending on the catchment considered. Results indicate that the transfer of model parameters in time may introduce a significant level of errors in simulations, meaning increased uncertainty in the various practical applications of these models (flow simulation, forecasting, design, reservoir management, climate change impact assessments, etc.). Testing model robustness with respect to this issue should help better quantify these uncertainties.
Integrated geophysical and hydrothermal models of flank degassing and fluid flow at Masaya volcano, Nicaragua
Authors: Pearson S. C. P. , Kiyosugi K. , Lehto H. L. , Saballos J. A. , Connor C. B. , Sanford W. E.
Published: April 2012

We investigate geologic controls on circulation in the shallow hydrothermal system of Masaya volcano, Nicaragua, and their relationship to surface diffuse degassing. On a local scale (∼250 m), relatively impermeable normal faults dipping at ∼60° control the flowpath of water vapor and other gases in the vadose zone. These shallow normal faults are identified by modeling of a NE‐SW trending magnetic anomaly of up to 2300 nT that corresponds to a topographic offset. Elevated SP and CO2 to the NW of the faults and an absence of CO2 to the SE suggest that these faults are barriers to flow. TOUGH2 numerical models of fluid circulation show enhanced flow through the footwalls of the faults, and corresponding increased mass flow and temperature at the surface (diffuse degassing zones). On a larger scale, TOUGH2 modeling suggests that groundwater convection may be occurring in a 3–4 km radial fracture zone transecting the entire flank of the volcano. Hot water rising uniformly into the base of the model at 1 × 10−5 kg/m2s results in convection that focuses heat and fluid and can explain the three distinct diffuse degassing zones distributed along the fracture. Our data and models suggest that the unusually active surface degassing zones at Masaya volcano can result purely from uniform heat and fluid flux at depth that is complicated by groundwater convection and permeability variations in the upper few km. Therefore isolating the effects of subsurface geology is vital when trying to interpret diffuse degassing in light of volcanic activity.
Biological response to the 1997–98 and 2009–10 El Niño events in the equatorial Pacific Ocean
Authors: Gierach Michelle M. , Lee Tong , Turk Daniela , McPhaden Michael J.
Published: April 2012

Changes in the physical environment associated with eastern Pacific (EP)‐El Niño and central Pacific (CP)‐El Niño events affect the biological response in the equatorial Pacific Ocean differently. However, such responses have not been adequately investigated, especially in terms of the relevant physical processes. This paper addresses the mechanistic differences in the biological response of the equatorial Pacific Ocean during the strongest CP‐ and EP‐El Niño to date (i.e., 1997–98 EP‐El Niño and 2009–10 CP‐El Niño) using satellite data and water mass pathway analysis based on an ocean reanalysis product. The 1997–98 EP‐El Niño was associated with a larger reduction of chlorophyll‐a (chl‐a) in the eastern equatorial Pacific (EEP) and the 2009–10 CP‐El Niño was associated with a larger reduction of chl‐a in the central equatorial Pacific (CEP). These biological responses were dependent on the strength and extent of westerly wind anomalies and their impact on horizontal and vertical processes. Horizontal advection was the primary contributor to differences in chl‐a between the two El Niño events in the CEP, whereas vertical advection and mixing were the dominant processes in the EEP.
Credible occurrence probabilities for extreme geophysical events: Earthquakes, volcanic eruptions, magnetic storms
Authors: Love Jeffrey J.
Published: April 2012

Statistical analysis is made of rare, extreme geophysical events recorded in historical data – counting the number of events k with sizes that exceed chosen thresholds during specific durations of time τ.Under transformations that stabilize data and model‐parameter variances, the most likely Poisson‐event occurrence rate,k/τ, applies for frequentist inference and, also, for Bayesian inference with a Jeffreys prior that ensures posterior invariance under changes of variables. Frequentist confidence intervals and Bayesian (Jeffreys) credibility intervals are approximately the same and easy to calculate:
, where z is a parameter that specifies the width, z = 1 (z = 2) corresponding to 1σ, 68.3% (2σ, 95.4%). If only a few events have been observed, as is usually the case for extreme events, then these “error‐bar” intervals might be considered to be relatively wide. From historical records, we estimate most likely long‐term occurrence rates, 10‐yr occurrence probabilities, and intervals of frequentist confidence and Bayesian credibility for large earthquakes, explosive volcanic eruptions, and magnetic storms.
Impacts of the production and consumption of biofuels on stratospheric ozone
Authors: Revell Laura E. , Bodeker Greg E. , Huck Petra E. , Williamson Bryce E.
Published: April 2012

Biofuels are becoming increasingly popular sources of renewable energy as economic pressures and environmental consequences encourage the use of alternatives to fossil fuels. However, growing crops destined for use as biofuels incurs large N2O emissions associated with the use of nitrogen‐based fertilizers. Besides being a greenhouse gas, N2O is also the primary source of stratospheric NOx (NO + NO2) which leads to stratospheric ozone depletion. In this paper, the potential effects on the ozone layer of a large‐scale shift away from fossil fuel use to biofuels consumption over the 21st century are examined. Under such a scenario, global‐mean column ozone decreases by 2.6 DU between 2010 and 2100 in contrast to a 0.7 DU decrease under a control simulation (the IPCC SRES B1 scenario for greenhouse gases) and a 9.1 DU increase under the more commonly used SRES A1B scenario. Two factors cause the decrease in ozone in the biofuels simulation: 1) large N2O emissions lead to faster rates of the ozone‐depleting NOx cycles and; 2) reduced CO2 emissions (due to less fossil fuel burning) lead to relatively less stratospheric cooling over the 21st century, which decreases ozone abundances. Reducing CO2 emissions while neglecting to reduce N2O emissions could therefore be damaging to the ozone layer.
Tectonic tremor and deep slow slip on the Alpine Fault
Authors: Wech A. G. , Boese C. M. , Stern T. A. , Townend J.
Published: April 2012

Tectonic tremor is characterized by persistent, low‐frequency seismic energy seen at major plate boundaries. Although predominantly associated with subduction zones, tremor also occurs along the deep extension of the strike‐slip San Andreas Fault. Here we present the first observations of tectonic tremor along New Zealand's Alpine Fault, a major transform boundary that is late in its earthquake cycle. We report tectonic tremor that occurred on the central section of the Alpine Fault on 12 days between March 2009 and October 2011. Tremor hypocenters concentrate in the lower crust at the downdip projection of the Alpine Fault; coincide with a zone of high P‐wave attenuation (low Qp) and bright seismic reflections; occur in the 25–45 km depth range, below the seismogenic zone; and may define the deep plate boundary structure extending through the lower crust and into the upper mantle. We infer this tremor to represent slow slip on the deep extent of the Alpine Fault in a fluid‐rich region marked by high attenuation and reflectivity. These observations provide the first indication of present‐day displacement on the lower crustal portion of the Australia–Pacific transform plate boundary.
Ozone temperature correlations in the upper stratosphere as a measure of chlorine content
Authors: Stolarski Richard S. , Douglass Anne R. , Remsberg Ellis E. , Livesey Nathaniel J. , Gille John C.
Published: April 2012

We use data from the Nimbus‐7 Limb Infrared Monitor of the Stratosphere (LIMS) for the 1978–1979 period together with data from the Upper Atmosphere Research Satellite Microwave Limb Sounder (UARS MLS) for the years 1993 to 1999, the Aura MLS for the years 2004 to 2011, and the Aura High Resolution Infrared Limb Sounder (HIRDLS) for the years 2005 to 2007 to examine ozone‐temperature correlations in the upper stratosphere. Our model simulations indicate that the sensitivity coefficient of the ozone response to temperature (Δln(O3)/Δ(1/T)) decreases as chlorine has increased in the stratosphere and should increase in the future as chlorine decreases. The data are in agreement with our simulation of the past. We also find that the sensitivity coefficient does not change in a constant‐chlorine simulation. Thus the change in the sensitivity coefficient depends on the change in chlorine, but not on the change in greenhouse gases. We suggest that these and future data can be used to track the impact of chlorine added to the stratosphere and also to track the recovery of the stratosphere as chlorine is removed under the provisions of the Montreal Protocol.
Amplification of wet and dry month occurrence over tropical land regions in response to global warming
Authors: Lintner Benjamin R. , Biasutti Michela , Diffenbaugh Noah S. , Lee Jung‐Eun , Niznik Mattie , Findell Kirsten L.
Published: April 2012

Quantifying how global warming impacts the spatiotemporal distribution of precipitation represents a key scientific challenge with profound implications for human welfare. Utilizing monthly precipitation data from Coupled Model Intercomparison Project (CMIP3) climate change simulations, the results here show that the occurrence of very dry (<0.5 mm/day) and very wet (>10 mm/day) months comprises a straightforward, robust metric of anthropogenic warming on tropical land region rainfall. In particular, differencing tropics‐wide precipitation frequency histograms for 25‐year periods over the late 21st and 20th centuries shows increased late‐21st‐century occurrence of histogram extremes both in the model ensemble and across individual models. Mechanistically, such differences are consistent with the view of enhanced tropical precipitation spatial gradients. Similar diagnostics are calculated for two 15‐year subperiods over 1979–2008 for the CMIP3 models and three observational precipitation products to assess whether the signature of late‐21st‐century warming has already emerged in response to recent warming. While both the observations and CMIP3 ensemble‐mean hint at similar amplification in the warmer (1994–2008) subinterval, the changes are not robust, as substantial differences are evident among the observational products and the intraensemble spread is large. Comparing histograms computed from the warmest and coolest years of the observational period further demonstrates effects of internal variability, notably the El Niño/Southern Oscillation, which appear to oppose the impact of quasi‐uniform anthropogenic warming on the wet tail of the monthly precipitation distribution. These results identify the increase of very dry and wet occurrences in monthly precipitation as a potential signature of anthropogenic global warming but also highlight the continuing dominance of internal climate variability on even bulk measures of tropical rainfall.
On the use of spatially discrete data to compute energy and mass balance
Authors: Lunati Ivan , Ciocca Francesco , Parlange Marc B.
Published: April 2012

In many practical applications the state of field soils is monitored by recording the evolution of temperature and soil moisture at discrete depths. We theoretically investigate the systematic errors that arise when mass and energy balances are computed directly from these measurements. We show that, even with no measurement or model errors, large residuals might result when finite difference approximations are used to compute fluxes and storage term. To calculate the limits set by the use of spatially discrete measurements on the accuracy of balance closure, we derive an analytical solution to estimate the residual on the basis of the two key parameters: the penetration depth and the distance between the measurements. When the thickness of the control layer for which the balance is computed is comparable to the penetration depth of the forcing (which depends on the thermal diffusivity and on the forcing period) large residuals arise. The residual is also very sensitive to the distance between the measurements, which requires accurately controlling the position of the sensors in field experiments. We also demonstrate that, for the same experimental setup, mass residuals are sensitively larger than the energy residuals due to the nonlinearity of the moisture transport equation. Our analysis suggests that a careful assessment of the systematic mass error introduced by the use of spatially discrete data is required before using fluxes and residuals computed directly from field measurements.