bluuebunny/crossref_metadata_2025 huggingface dataset:
Stellar-mass black holes in star clusters: implications for gravitational-wave radiation
Authors: Banerjee Sambaran , Baumgardt Holger , Kroupa Pavel
Published: January 2010

We study the dynamics of stellar-mass black holes (BHs) in star clusters, with particular attention to the formation of BH–BH binaries, which are interesting as sources of gravitational waves (GWs). We examine the properties of these BH–BH binaries through direct N-body simulations of Plummer clusters of N ≤ 105 low-mass stars with an initial population of stellar-mass BHs, using the nbody6 code. We find that the stellar-mass BHs segregate rapidly into the cluster core and form a dense subcluster of BHs in which BH–BH binaries form through three-body encounters. While most BH binaries are ejected from the cluster by recoils due to superelastic encounters with the single BHs, we find that for clusters with N ≳ 5 × 104, typically a few of them harden sufficiently so that they can merge via GW emission within the cluster. Also, for each of such clusters there are a few escaping BH binaries that merge within a Hubble time, with most merger times being within a few Gyr. These results imply that the intermediate-age massive clusters constitute the most important class of star cluster candidates that can produce dynamical BH–BH mergers at the present epoch. The BH–BH merger rates obtained from our computations imply a significant detection rate (~30 yr−1) for the proposed Advanced LIGO GW detector.
On the origin of the hypervelocity runaway star HD 271791
Authors: Gvaramadze V. V.
Published: January 2010

We discuss the origin of the early-B-type runaway star HD 271791 and show that its extremely high velocity (≃530 − 920km s−1) cannot be explained within the framework of the binary–supernova ejection scenario. Instead, we suggest that HD 271791 attained its peculiar velocity in the course of a strong dynamical encounter between two hard, massive binaries or through an exchange encounter between a hard, massive binary and a very massive star, formed through runaway mergers of ordinary massive stars in the dense core of a young massive star cluster.
Close pairs: keys to comprehension of star cluster evolution
Authors: Vanbeveren Dany
Published: January 2010

In this review I first summarize why binaries are key objects in the study of stellar populations, to understand the evolution of star clusters and galaxies, and thus to understand the universe. I then focus on four specific topics:

(i)

the formation (through binaries) and evolution of very massive stars in dense clusters and the importance of stellar-wind mass loss. I discuss preliminary computations of wind mass-loss rates of very massive stars performed with the Munich hydrodynamical code and the influence of these new rates on the possible formation of an intermediate-mass black hole in the cluster MGG 11 in M82;

(ii)

the evolution of intermediate-mass binaries in a starburst with special emphasis on the variation of the supernova (SN) Ia rate (i.e., on the delayed time distribution of SNe Ia). A comparison with SN Ia rates in elliptical galaxies may provide important clues to SN Ia models as well as to the evolution of SN Ia progenitors;

(iii)

the evolution of double-neutron-star mergers in a starburst (i.e., the delayed time distribution of these mergers) and what this tells us about the suggestion that these mergers may be important production sites of r-process elements;

(iv)

the possible effect of massive binaries on the self-enrichment of globular clusters.
A new method to measure stellar mass-loss rates
Authors: Kalirai Jason S.
Published: January 2010

The total stellar mass loss that a star suffers through post-main-sequence evolution is of vital importance to understand its subsequent evolution. The mass-loss rate along the first-ascent red-giant branch alone determines the upper red-giant-branch luminosity function and horizontal-branch morphology. The distribution of stars in these phases directly affects our interpretation of the integrated colors of distant galaxies, and is therefore of fundamental importance for galaxy formation and evolution studies in the higher-redshift Universe. Yet, these mass-loss rates, especially as a function of age and metallicity, are very poorly constrained in current models. I present new constraints on this field based on imaging and spectroscopic observations of the end products from this evolution, white dwarfs. By studying the mass distribution of these dead stars in nearby star clusters with a range of (known) ages and metallicities, we can directly constrain the mass-loss rates of stars across a range of environments. These observations directly impact several fields in astrophysics, including our knowledge of the enrichment of the interstellar medium, our ability to construct population synthesis models to interpret galaxy colors and the general interpretation of the sources and processes responsible for the observed ultraviolet upturn in elliptical galaxies.
The multipopulation phenomenon in Galactic globular clusters: M4 and M22
Authors: Villanova S. , Piotto G. , Marino A. F. , Milone A. P. , Bellini A. , Bedin L. R. , Momany Y. , Renzini A.
Published: January 2010

We present an abundance analysis based on high-resolution spectra of red-giant-branch (RGB) stars in the Galactic globular clusters NGC 6121 (M4) and NGC 6656 (M22). Our aim was to study their stellar population in the context of the multipopulation phenomenon recently discovered to affect some globular clusters. Analysis was performed for the following elements: O, Na, Mg, Al, Ca, Fe, Y, and Ba. Spectroscopic data were completed by high-precision wide-field U BV IC ground-based photometry and HST/ACS observations. For M4, we find a well-defined Na–O anticorrelation composed of two distinct groups of stars with significantly different Na and O content. The two groups of Na-rich and Na-poor stars populate two different regions along the RGB. As regards M22, Na and O follow the well-known anticorrelation found in many other GCs. However, at odds with M4, it appears to be continuous without any hint of clumpiness. On the other hand, we identified two clearly separated groups of stars with significantly different abundances of the s-process elements Y, Zr and Ba. The relative numbers of the members of both groups are very similar to the ratio of the stars in the two subgiant branches of M22 recently found by Piotto (2009). The s-element-rich stars are also richer in iron and have higher Ca abundances. This makes M22 the second cluster after ω Centauri where an intrinsic spread in Fe was found. Both spectroscopic and photometric results imply the presence of two stellar populations in M4 and M22, even if both clusters have completely different characteristics.
Further developments in star cluster spectral libraries
Authors: Ahumada Andrea V. , Clariá Juan J. , Bica Eduardo , Piatti Andrés E. , Santos João F. C. , Talavera M. Lorena , Palma Tali , Pavani Daniela B. , Parisi M. Celeste , Torres M. Cristina , Dutra Carlos M.
Published: January 2010

We present flux-calibrated integrated spectra in the optical spectral range of Galactic open clusters (GOCs) and Magellanic Cloud (MC) stellar clusters (SCs) obtained at CASLEO (Argentina). The SC parameters were derived using the equivalent-width (EW) method and the template-matching procedure by comparing the line strengths and continuum distribution of the cluster spectra with those of template spectra with known parameters. MC cluster reddening values were also estimated by interpolation between the available extinction maps. The derived ages for the GOCs range from 3 Myr to 4 Gyr, while those of the MC SCs vary from 3 Myr to 7 Gyr. E(B−V) colour-excess values in the MCs appear to be all lower than 0.17 mag, while those of the GOCs range from 0.00 to 2.40 mag. The present data led us to upgrade the spectral libraries of reference spectra or templates of solar and MC metallicities.
Star clusters as building blocks for dSph galaxy formation
Authors: Assmann P. , Fellhauer M. , Wilkinson M. I.
Published: January 2010

We study numerically the formation of dSph galaxies. Intense starbursts, e.g., in gas-rich environments, typically produce a few to a few hundred young star clusters within a region of just a few hundred pc. The dynamical evolution of these star clusters may explain the formation of the luminous component of dwarf spheroidal (dSph) galaxies. Here, we perform a numerical experiment to show that the evolution of star cluster complexes in dark-matter haloes can explain the formation of the luminous components of dSph galaxies.
UBVRI CCD photometric study of southern open star clusters observed at Pico dos Dias Observatory (LNA/Brazil)
Authors: Caetano Thiago Costa , Dias Wilton S.
Published: January 2010

Open clusters have long been recognized as important objects to investigate aspects of Galactic structure such as the location of spiral arms, Galactic dynamics or even the chemical-abundance gradients in the Galactic disk. Great effort has been dedicated to studies of these objects throughout the past few years to determine parameters like age, distance, reddening, metallicity as well as kinematic information in a systematic and consistent manner. In this work, we present results on several open clusters selected from the DAML02 catalog that have been observed and investigated for the first time. CCD UBVRI (Johnsons–Cousins system) observations were carried out in 2009 using the 60 cm telescope of the Pico dos Dias Observatory (LNA/Brazil). The color–color and color–magnitude diagrams were analyzed for each cluster with the help of a program written by our group, which allows handling photometric and astrometric data simultaneously. We determined the fundamental parameters (reddening, distance and age) using the main-sequence fitting method, taking into account kinematic information of individual stars in the clusters. The mean proper motion and radial velocity were estimated using a set of stars selected photometrically.
The fragmentation of expanding shells – limitations of the thin-shell model
Authors: Dale Jim , Wünsch Richard , Palouš Jan , Whitworth Ant
Published: January 2010

We study the fragmentation of expanding shells in the context of the linear thin-shell analysis. We simulate shell fragmentation using the flash AMR code and a variant of the Benz SPH code.
Investigation of star clusters found in the 2mass catalog
Authors: Glushkova Elena , Yadav Ramakant , Koposov Sergey
Published: January 2010

We have launched a program of UBVR CCD photometric investigations of new clusters detected in the 2mass catalog based on an automatic detection method, which uses a convolution with a density function. Three new clusters, Koposov 12, Koposov 53 and Koposov 77 were observed in UBVI with the 104 cm Sampurnanand telescope located at ARIES, Manora Peak, India. Their ages, distances, color excesses and metallicities have been derived using photometric data.
Constraining star cluster disruption mechanisms
Authors: Konstantopoulos I. S. , Bastian N. , Gieles M. , Lamers H. J. G. L. M.
Published: January 2010

Star clusters are found in all sorts of environments, and their formation and evolution is inextricably linked to the star-formation process. Their eventual destruction can result from a number of factors at different times, but the process can be investigated as a whole through the study of cluster age distributions. Observations of populous cluster samples reveal a distribution following a power law of index approximately −1. In this work, we use M33 as a test case to examine the age distribution of an archetypal cluster population and show that it is, in fact, the evolving shape of the mass detection limit that defines this trend. That is to say, any magnitude-limited sample will appear to follow a dN/dτ = τ−1 relation, while cutting the sample according to mass gives rise to a composite structure, perhaps implying a dependence of the cluster disruption process on mass. In the context of this framework, we examine different models of cluster disruption from both theoretical and observational perspectives.
Metallicities of intermediate-age and old star clusters in the Large Magellanic Cloud
Authors: Kučinskas Arūnas , Dobrovolskas Vidas , Černiauskas Algimantas , Lazauskaitė Roma , Tanabé Toshihiko
Published: January 2010

We derive photometric metallicities for 56 intermediate-age and old star clusters in the Large Magellanic Cloud from the slopes of their red-giant branches in near-infrared color–magnitude diagrams (CMDs). The cluster sample covers the LMC bar and disk to a distance of ~2 kpc from the LMC center. The derived cluster metallicity distribution spans a range of [Fe/H] = +0.0 . . . 1.4 and is similar to the metallicity distribution of field stars. We find that the average cluster metallicities in certain fields of the LMC bar and disk may be different, but there seems to be no compelling evidence for a global cluster metallicity gradient in the LMC.
Evolution and appearance of Be stars in SMC clusters
Authors: Martayan C. , Baade D. , Frémat Y. , Zorec J.
Published: January 2010

Star clusters are privileged laboratories for studying the evolution of massive stars (OB stars). One particularly interesting question concerns the phases during which the classical Be stars occur, which—unlike HAe/Be stars—are not pre-main-sequence objects, nor supergiants. Rather, they are extremely rapidly rotating B-type stars with a circumstellar decretion disk formed by episodic ejections of matter from the central star. To study the impact of mass, metallicity, and age on the Be phase, we observed Small Magellanic Cloud (SMC) open clusters with two different techniques: (i) with the ESO–WFI in slitless mode, which allowed us to find the brighter Be and other emission-line stars in 84 SMC open clusters, and (ii) with the VLT–FLAMES multifiber spectrograph to determine accurately the evolutionary phases of Be stars in the Be-star-rich SMC open cluster NGC 330. Based on a comparison to the Milky Way, a model of Be stellar evolution, appearance as a function of metallicity and mass, and spectral type is developed, involving the fractional critical rotation rate as a key parameter.
massclean(MASSive CLuster Evolution and ANalysis Package): description, tests, and results
Authors: Popescu Bogdan , Hanson M. M.
Published: January 2010

masscleanis a new, sophisticated and robust stellar cluster image and photometry simulation package. This package can create color–magnitude diagrams and standard FITS images in any of the traditional optical and near-infrared bands based on cluster characteristics input by the user, including but not limited to distance, age, mass, radius and extinction. At the limit of very distant, unresolved clusters, we have checked the integrated colors created inmasscleanagainst those from other simple stellar population models, with consistent results. Because the algorithm populates the cluster with a discrete number of tenable stars, it can be used as part of a Monte Carlo method to derive the probabilistic range of characteristics (integrated colors, for example) consistent with a given cluster mass and age. We present the first ever mass-dependent integrated colors as a function of age, derived from over 100 000 Monte Carlo runs, which can be used to improve the current age-determination methods for stellar clusters.
Hierarchical clustering in the Local Group dwarf galaxy NGC 6822
Authors: Schmeja S. , Gouliermis D. A. , Klessen R. S. , de Blok W. J. G. , Walter F.
Published: January 2010

Star formation appears to be clumped into a hierarchy of structures, from giant molecular clouds down to individual cores and clusters, which are often hierarchical themselves, showing significant substructure. This has been demonstrated for our Galaxy through the application of sophisticated statistical methods, in particular the nearest-neighbour density and the minimum spanning tree (MST), to different star-forming regions. Here we present our analysis of clustered star formation as demonstrated through the detection of structures of young stellar populations in the dwarf star-forming galaxy NGC 6822.
Pre-main-sequence stars in the stellar association N 11 in the Large Magellanic Cloud: clustering properties
Authors: Vallenari Antonella , Sordo Rosanna , Chiosi Emanuela
Published: January 2010

Magellanic Clouds are of extreme importance to study the star-formation process in low-metallicity environments. Here, we discuss the clustering properties of the pre-main-sequence candidates and young embedded stellar objects in N 11, located in the Large Magellanic Cloud. Deep archival HST/ACS photometry is used to derive color–magnitude diagrams of the associations in N 11 and of the foreground field population. These data are complemented by archival infrared Spitzer data which allow detection of young embedded stellar objects. The spatial distribution of the pre-main-sequence candidates and young embedded stellar objects is discussed. The degree of clustering is derived using the minimal-spanning-tree method. No significant difference is found in clustering degree of young blue main-sequence stars and faint pre-main-sequence candidates, suggesting that they might be part of the same formation process.
Bridging galactic star formation from intermediate to local epochs
Authors: Voyer Elysse N. , de Mello Duilia F. , Gardner Jonathan P. , Siana Brian , Teplitz Harry
Published: January 2010

Starburst galaxies trace the star-formation history of the Universe throughout cosmological time. Several studies have shown that the star-formation-rate density of the Universe begins to steadily decline after the Universe had aged ~ 5.8 Gyr (redshifts z ~ 1). However, we do not yet fully understand the mechanism behind this shift in star formation at intermediate z. One possibility is that during this epoch galaxies underwent ‘downsizing,’ a shift in star formation being dominated by high- to lower-mass galaxies. Rest-frame ultraviolet (UV) observations of starburst galaxies reveal regions of young stellar clusters where massive O and B stars dominate the luminosity. Observations in the FUV (~ 1500 Å) can be used to detect starburst galaxies at z < 1 because the bright end of the rest-frame FUV spectrum is not redshifted much, and is observable in the FUV filter. Alternatively, the rest-frame FUV light from starburst galaxies at higher redshifts is shifted to longer wavelengths and must be observed in redder filters. We present a study of the starburst population at intermediate z from FUV data taken with Hubble's Solar Blind Channel (SBC) of the Advanced Camera for Surveys (ACS). The number counts of FUV galaxies as a function of magnitude provide a direct statistical measure of the density and evolution of starbursts, and subsequently of the stellar clusters formed within these galaxies' environments. We present a comparison between the FUV starburst-galaxy counts at this epoch, and the local FUV counts of starbursts observed with GALEX.
Label-free RF biosensors for human cell dielectric spectroscopy
Authors: Dalmay Claire , Pothier Arnaud , Cheray Mathilde , Lalloue Fabrice , Jauberteau Marie-Odile , Blondy Pierre
Published: January 2010

This paper presents an original biosensor chip allowing determination of intrinsic relative permittivity of biological cells at microwave frequencies. This sensor permits non-invasive cell identification and discrimination using an RF signal to probe intracellular medium of biological samples. Indeed, these sensors use an RF planar resonator that allows detection capabilities on less than 10 cells, thanks to the microscopic size of its sensitive area. Especially, measurements between 15 and 35 GHz show the ability label-free biosensors to differentiate two human cell types using their own electromagnetic characteristics. The real part of permittivity of cells changes from 20 to 48 for the nervous system cell types studied. The proposed biodetection method is detailed and we show how the accuracy and the repeatability of measurements have been improved to reach reproducible measurements.
Optically modulated III–V nitride-based high-power IMPact Avalanche Transit Time oscillator at Millimeter-wave window frequency
Authors: Mukherjee Moumita , Roy Sitesh Kumar
Published: January 2010

Extensive simulation experiments are carried out for the first time, to study the optical modulation of the high- frequency characteristics of III–V GaN-(gallium nitride) based top-mounted and flip-chip IMPact Avalanche Transit Time (IMPATT) oscillators at MM-wave window frequency (140.0 GHz). It is found that the un-illuminated GaN IMPATT is capable of delivering a RF power of 5.6 W with an efficiency of 23.5% at 145.0 GHz. Frequency up-chirping of 6.0 GHz and a degradation of RF power output by almost 15.0% are further observed in case of photo-illuminated FC IMPATT. The study reveals that compared to predominate electron photocurrent in top-mounted IMPATT, photo-generated leakage current dominated by hole in flip-chip IMPATT has more pronounced effect on the GaN-based device as regards the frequency chirping and decrease of negative conductance and total negative resistance per unit area of the device. The inequality in the magnitudes of electron and hole ionization rates in the wide band gap semiconductor has been found to be correlated with the above results. The study reveals that GaN IMPATT is a potential candidate for replacing conventional IMPATTs at high-frequency operation. These results are useful for practical realization of optically controlled GaN-based high-power IMPATTs for application in MM-wave communication systems.
Measurement of the density of magnetized fusion plasma using microwave reflectometry
Authors: Giacalone Jean-Claude , Sabot Roland , Clairet Frédéric , Bottereau Christine , Molina Diego
Published: January 2010

About 25 years have elapsed since the first measurement by a FW-CW (called fast sweeping) reflectometer of the electronic density in magnetized fusion plasma. Substituting tube sources with solid-state components has resulted in a decrease of the sweeping time from the millisecond to the microsecond range. Based on voltage control oscillators and on active frequency multipliers, four profile reflectometers covering the range 33–155 GHz are in operation on Tore-Supra tokamak. Their originality is the use of one source for the launched and reference signal, although the detection is heterodyne. Indeed, a single side band modulator shifts the launched frequency ahead of frequency multipliers. With a sweeping time comparable to the plasma turbulence characteristic time the density profile is frozen. The density profile is then reliably measured with high radial and temporal resolution.
Kardiovaskuläre Folgen des obstruktiven Schlafapnoe-Syndroms
Authors: Kohler  , Russi  , Bloch
Published: January 2010

Das obstruktive Schlafapnoe-Syndrom (OSAS) ist eine hochprävalente, schlaf-assoziierte Atmungsstörung, welche mit Hypopnoen/Apnoen, Aufwachreaktionen sowie erhöhter Tagesmüdigkeit einhergeht. Die Effekte des OSAS beinhalten unter anderem auch gefässschädigende Wirkungen, weshalb angenommen wird, dass das OSAS ein unabhängiger kardiovaskulärer Risikofaktor ist. Ein kausaler Zusammenhang zwischen dem OSAS und kardiovaskulären Erkrankungen wurde allerdings bisher nur für die arterielle Hypertonie und für die Herzinsuffizienz bewiesen. Die Evidenz dafür, dass das OSAS auch bei der Entstehung des Herzinfarkts oder Schlaganfalls eine Rolle spielt und eine OSAS-Therapie die kardiovaskuläre Morbidität und Mortalität reduziert, ist bisher noch limitiert. Die Ergebnisse von mehreren laufenden internationalen Multizenter-Studien, welche den Effekt der OSAS-Therapie auf kardiovaskuläre Ereignisse und die Mortalität untersuchen, werden deshalb mit grossem Interesse erwartet.
Heterogeneity in hydraulic conductivity and its role on the macroscale transport of a solute plume: From measurements to a practical application of stochastic flow and transport theory
Authors: Sudicky E. A. , Illman W. A. , Goltz I. K. , Adams J. J. , McLaren R. G.
Published: January 2010

The spatial variability of hydraulic conductivity in a shallow unconfined aquifer located at North Bay, Ontario, composed of glacial‐lacustrine and glacial‐fluvial sands, is examined in exceptional detail and characterized geostatistically. A total of 1878 permeameter measurements were performed at 0.05 m vertical intervals along cores taken from 20 boreholes along two intersecting transect lines. Simultaneous three‐dimensional (3‐D) fitting of Ln(K) variogram data to an exponential model yielded geostatistical parameters for the estimation of bulk hydraulic conductivity and solute dispersion parameters. The analysis revealed a Ln(K) variance equal to about 2.0 and 3‐D anisotropy of the correlation structure of the heterogeneity (λ1, λ2, and λ3 equal to 17.19, 7.39, and 1.0 m, respectively). Effective values of the hydraulic conductivity tensor and the value of the longitudinal macrodispersivity were calculated using the theoretical expressions of Gelhar and Axness (1983). The magnitude of the longitudinal macrodispersivity is reasonably consistent with the observed degree of longitudinal dispersion of the landfill plume along the principal path of migration. Variably saturated 3‐D flow modeling using the statistically derived effective hydraulic conductivity tensor allowed a reasonably close prediction of the measured water table and the observed heads at various depths in an array of piezometers. Concomitant transport modeling using the calculated longitudinal macrodispersivity reasonably predicted the extent and migration rates of the observed contaminant plume that was monitored using a network of multilevel samplers over a period of about 5 years. It was further demonstrated that the length of the plume is relatively insensitive to the value of the longitudinal macrodispersivity under the conditions of a steady flow in 3‐D and constant source strength. This study demonstrates that the use of statistically derived parameters based on stochastic theories results in reliable large‐scale 3‐D flow and transport models for complex hydrogeological systems. This is in agreement with the conclusions reached by Sudicky (1986) at the site of an elaborate tracer test conducted in the aquifer at the Canadian Forces Base Borden.
A New “Polar” Program: Third Pole Environment (TPE) Workshop; Beijing, China, 14–16 August 2009
Authors: Yao Tandong , Greenwood Greg
Published: January 2010

The highland core of Asia—the Qinghai‐Tibetan Plateau and the mountain ranges that surround it—has a large and complex cryosphere, which alone would earn it the title the “Third Pole” and justify greater attention. Like the other two poles, a geographic shift in the freezing line will drastically change the cryosphere, the water cycle, and the biosphere. Unlike the other two poles, the Third Pole is inhabited, and a considerable fraction of humanity in South Asia and East Asia depends on its resources, especially its water. To launch an international research program to study this important region, the Chinese Academy of Sciences Institute of Tibetan Plateau Research (ITP) hosted the Third Pole Environment (TPE) Workshop in Beijing. Approximately 70 scientists from 15 different countries attended the workshop.
Magnitudes and sources of dissolved inorganic phosphorus inputs to surface fresh waters and the coastal zone: A new global model
Authors: Harrison John A. , Bouwman A. F. , Mayorga Emilio , Seitzinger Sybil
Published: January 2010

As a limiting nutrient in aquatic systems, phosphorus (P) plays an important role in controlling freshwater and coastal primary productivity and ecosystem dynamics, increasing frequency and severity of harmful and nuisance algae blooms and hypoxia, as well as contributing to loss of biodiversity. Although dissolved inorganic P (DIP) often constitutes a relatively small fraction of the total P pool in aquatic systems, its bioavailability makes it an important determinant of ecosystem function. Here we describe, apply, evaluate, and interpret an enhanced version of the Global Nutrient Export from Watersheds (NEWS)–DIP model: NEWS‐DIP–Half Degree (NEWS‐DIP‐HD). Improvements to NEWS‐DIP‐HD over the original NEWS DIP model include (1) the preservation of spatial resolution of input data sets at the 0.5 degree level and (2) explicit downstream routing of water and DIP from half‐degree cell to half‐degree cell using a global flow‐direction representation. NEWS‐DIP explains 78% and 62% of the variability in per‐basin DIP export (DIP load) for U.S. Geological Survey (USGS) and global stations, respectively, similar to the original NEWS‐DIP model and somewhat more than other global models of DIP loading and export. NEWS‐DIP‐HD output suggests that hot spots for DIP loading tend to occur in urban centers, with the highest per‐area rate of DIP loading predicted for the half‐degree grid cell containing Tokyo (6366 kg P km−2 yr−1). Furthermore, cities with populations >100,000 accounted for 35% of global surface water DIP loading while covering less than 2% of global land surface area. NEWS‐DIP‐HD also indicates that humans supply more DIP to surface waters than natural weathering over the majority (53%) of the Earth's land surface, with a much larger area dominated by DIP point sources than nonpoint sources (52% versus 1% of the global land surface, respectively). NEWS‐DIP‐HD also suggests that while humans had increased DIP input to surface waters more than fourfold globally by the year 2000, human activities such as dam construction and consumptive water use have somewhat moderated the effect of humans on P transport by preventing (conservatively) 0.35 Tg P yr−1 (∼20% of P inputs to surface waters) from reaching coastal zones globally.
Pore water chemistry of the Mariana serpentinite mud volcanoes: A window to the seismogenic zone
Authors: Hulme Samuel M. , Wheat C. Geoffery , Fryer Patricia , Mottl Michael J.
Published: January 2010

In 2003, we conducted a survey of 11 serpentinite mud volcanoes in the Mariana fore arc. Here we report sediment pore water data from navigated gravity and piston cores and from push cores collected by the ROV system Jason2‐Medea. Systematic variations in profiles of pore water chemical compositions from these mud volcanoes are consistent with models that include active upflow of pore water relative to the surrounding serpentinite matrix. The speed of upwelling, based on fits of an advection‐diffusion model to observed data (K, Na, Rb, and Cs), reaches a maximum of 36 cm/yr at Big Blue Seamount. Results from these simulations constrain the pore water composition at depth and the degree of additional alteration as the pore water ascends through the sampled section. For example, the transition metals (e.g., Mn, Fe, Co, Ni, Cu, and Mo) are mobilized under conditions of low upwelling speeds and microbial activity. Similarly, the rare earth elements (REE) show evidence of near‐surface alteration. In addition to these surficial reactions, distinctive pore water compositional patterns exist as a function of the distance from the trench axis, which is a proxy for the depths of water generation from the downgoing plate below each seamount. Systematic trends in the chemical composition of these slab‐sourced fluids are consistent with increasing temperature and pressure at depth west of the trench. These trends include an increase in K, sulfate, carbonate alkalinity, Na/Cl, B, Mn, Fe, Co, Rb, Cs, Gd/Tb, Eu, and light REE (LREE) and a decrease in Ca, Sr, and Y with increasing distance from the trench. Mg and U are universally depleted in the upwelling water. We constrain the thermal conditions along the décollement using concentrations of fluid mobile elements (K, B, Cs, and Rb) and the mobilization of LREE relative to heavy REE (HREE). The 80°C isotherm is estimated at a depth of 15 km between Blue Moon Seamount and Cerulean Springs. At slab depths of 17 to 24 km, pore waters lack significant Rb and K enrichments relative to seawater, suggesting an upper bound near 150°C. There is an observed enrichment in LREE relative to HREE at Big Blue Seamount (slab depth 25 km) indicating that the décollement at this site is ∼200°C. The relative mobilization of Cs outpaced that of Rb at all seamounts sampled in this survey. On the basis of laboratory experiments, this observation sets an upper limit of ∼350°C at a depth of 30 km below the seafloor.
Calderas Bottom‐to‐Top: An Online Seminar and Field Trip
Authors: Wilcock Jack , Longpré Marc‐Antoine , De Moor J. Maarten , Ross Jake , Zimmerer Matt
Published: January 2010

Caldera‐related processes have deep implications in Earth science and are important to the general public. To the geologist, calderas are surface manifestations of large magma reservoirs and the source of some of the largest eruptions on Earth. For society, these volcanoes represent not only an extreme volcanic hazard but also a potential source of abundant geothermal energy and metal ore deposits.

During February–April 2009, an innovative, online course entitled “Calderas: Bottom‐to‐top” was offered across several universities to students interested in investigating caldera‐forming processes associated with “supervolcanoes.” Supervolcanoes have the ability to spew hundreds to thousands of cubic kilometers of material from large magma chambers pooled in the Earth's crust. A caldera‐forming eruption results from overpressurization of the chamber and leads to formation of large depressions, tens of kilometers in diameter.
Erratum: Interactions between gut microbiota, host genetics and diet relevant to development of metabolic syndromes in mice
Authors: Zhang Chenhong , Zhang Menghui , Wang Shengyue , Han Ruijun , Cao Youfang , Hua Weiying , Mao Yuejian , Zhang Xiaojun , Pang Xiaoyan , Wei Chaochun , Zhao Guoping , Chen Yan , Zhao Liping
Published: January 2010

Correction to: The ISME Journal (2010) 4, 232–241; doi:10.1038/ismej.2009.112; published online 29 October 2009 Since the publication of this paper, the authors have noticed an error in Figure 4. The correct figure is shown here. The authors would like to apologize for any inconvenience this may have caused.
Deciphering a transcriptional regulatory code: modeling short‐range repression in the Drosophila embryo
Authors: Fakhouri Walid D , Ay Ahmet , Sayal Rupinder , Dresch Jacqueline , Dayringer Evan , Arnosti David N
Published: January 2010

Systems biology seeks a genomic‐level interpretation of transcriptional regulatory information represented by patterns of protein‐binding sites. Obtaining this information without direct experimentation is challenging; minor alterations in binding sites can have profound effects on gene expression, and underlie important aspects of disease and evolution. Quantitative modeling offers an alternative path to develop a global understanding of the transcriptional regulatory code. Recent studies have focused on endogenous regulatory sequences; however, distinct enhancers differ in many features, making it difficult to generalize to other cis‐regulatory elements. We applied a systematic approach to simpler elements and present here the first quantitative analysis of short‐range transcriptional repressors, which have central functions in metazoan development. Our fractional occupancy‐based modeling uncovered unexpected features of these proteins’ activity that allow accurate predictions of regulation by the Giant, Knirps, Krüppel, and Snail repressors, including modeling of an endogenous enhancer. This study provides essential elements of a transcriptional regulatory code that will allow extensive analysis of genomic information in Drosophila melanogaster and related organisms.
Synthesis of bismuth vanadate nanoplates with exposed {001} facets and enhanced visible-light photocatalytic properties
Authors: Xi Guangcheng , Ye Jinhua
Published: January 2010

Well-defined m-BiVO4 nanoplates with exposed highly active (001) faces were synthesized by a facile hydrothermal route, which exhibits greatly enhanced activity in the visible-light photocatalysis.
Synchronous optical and electrical detection of biomolecules traversing through solid-state nanopores
Authors: Soni Gautam V. , Singer Alon , Yu Zhiliang , Sun Yingjie , McNally Ben , Meller Amit
Published: January 2010

We present a novel method for integrating two single-molecule measurement modalities, namely, total internal reflection microscopy and electrical detection of biomolecules using nanopores. Demonstrated here is the electrical measurement of nanopore based biosensing performed simultaneously and in-sync with optical detection of analytes. This method makes it possible, for the first time, to visualize DNA and DNA-protein complexes translocating through a nanopore with high temporal resolution (1000 frames/s) and good signal to background. This paper describes a detailed experimental design of custom optics and data acquisition hardware to achieve simultaneous high resolution electrical and optical measurements on labeled biomolecules as they traverse through a ∼4 nm synthetic pore. In conclusion, we discuss new directions and measurements, which this technique opens up.
Carbon nanotube-Si diode as a detector of mid-infrared illumination
Authors: Ong Pang-Leen , Euler William B. , Levitsky Igor A.
Published: January 2010

We report a room temperature mid-infrared photodetector based on a carbon nanotube-silicon heterojunction nanostructure. The observed mid-infrared band (8–12 μm) in the photocurrent spectrum is consistent with the estimated band gap energy of semiconducting multiwall nanotubes (15 to 30 nm diameter). The fast response time (16 ms) and small temperature change (∼10−8 K) upon infrared light suggest that the photocurrent response is not due to bolometric effect. We determined that the primary mechanism of the photocurrent in this spectral range is associated with photon absorption of semiconducting multiwalled carbon nanotubes followed by charge separation at the interface, their transport, and collection at the external electrodes.
Intensity correlation measurement system by picosecond single shot soft x-ray laser
Authors: Kishimoto Maki , Namikawa Kazumichi , Sukegawa Kouta , Yamatani Hiroshi , Hasegawa Noboru , Tanaka Momoko
Published: January 2010

We developed a new soft x-ray speckle intensity correlation spectroscopy system by use of a single shot high brilliant plasma soft x-ray laser. The plasma soft x-ray laser is characterized by several picoseconds in pulse width, more than 90% special coherence, and 1011 soft x-ray photons within a single pulse. We developed a Michelson type delay pulse generator using a soft x-ray beam splitter to measure the intensity correlation of x-ray speckles from materials and succeeded in generating double coherent x-ray pulses with picosecond delay times. Moreover, we employed a high-speed soft x-ray streak camera for the picosecond time-resolved measurement of x-ray speckles caused by double coherent x-ray pulse illumination. We performed the x-ray speckle intensity correlation measurements for probing the relaxation phenomena of polarizations in polarization clusters in the paraelectric phase of the ferroelectric material BaTiO3 near its Curie temperature and verified its performance.
Room temperature transparent ferromagnetism in 200 keV Ni2+ ion implanted pulsed laser deposition grown ZnO/sapphire film
Authors: Pandey B. , Ghosh S. , Srivastava P. , Kumar P. , Kanjilal D. , Zhou S. , Schmidt H.
Published: January 2010

Intrinsic ferromagnetism at room temperature has been observed in ZnO/sapphire films by implantation of 200 keV Ni2+ ions with fluences 6×1015, 8×1015, 1×1016, and 2×1016 ions/cm2. Crystalline phases are identified by glancing angle x-ray diffraction, which shows no extra phase in the implanted films. Highest saturation magnetization (Ms) is observed in the film implanted with the fluence of 8×1015 ions/cm2 as examined by superconducting quantum interference device magnetometry. This film has almost 80% transmittance across visible wavelength range and hence a potential candidate of transparent ferromagnetic semiconductor. Defectlike oxygen vacancies in the films are studied by x-ray photoelectron spectroscopy. Ferromagnetism of the films is explained on the basis of bound magnetic polaron model.
Calibrating the atomic balance by carbon nanoclusters
Authors: Song Fengqi , Wang Xuefeng , Powles Rebecca C. , He Longbing , Marks Nigel A. , Zhao Shifeng , Wan Jianguo , Liu Zongwen , Zhou Jianfeng , Ringer Simon P. , Han Min , Wang Guanghou
Published: January 2010

Carbon atoms are counted at near atomic-level precision using a scanning transmission electron microscope calibrated by carbon nanocluster mass standards. A linear calibration curve governs the working zone from a few carbon atoms up to 34 000 atoms. This linearity enables adequate averaging of the scattering cross sections, imparting the experiment with near atomic-level precision despite the use of a coarse mass reference. An example of this approach is provided for layer counting of stacked graphene sheets. Suspended graphene sheets with a size below 100 nm are visualized, providing quantitative measurement in a regime inaccessible to optical and scanning probe methods.
Wide-band capacitance measurement on a semiconductor double quantum dot for studying tunneling dynamics
Authors: Ota Takeshi , Hayashi Toshiaki , Muraki Koji , Fujisawa Toshimasa
Published: January 2010

We propose and demonstrate wide-band capacitance measurements on a semiconductor double quantum dot (DQD) to study tunneling dynamics. By applying phase-tunable high-frequency signals independently to the DQD and a nearby quantum-point-contact charge detector, we successfully measure current proportional to the capacitance associated with the single-electron motion over a wide frequency range from Hz to a few tens of GHz. Analyzing the phase and the frequency dependence of the signal allows us to extract the characteristic tunneling rates. We show that, by applying this technique to the interdot tunnel coupling regime, quantum capacitance reflecting the strength of the quantum-mechanical coupling can be measured.
Tailoring a plasma focus as hard x-ray source for imaging
Authors: Hussain S. , Shafiq M. , Zakaullah M.
Published: January 2010

An investigation on temporal and spatial properties of hard x-rays (15–88 keV) emitted in a 5.3 kJ plasma focus using Si pin diodes and a pinhole camera is reported. The maximum yield of hard x-rays of 15–88 keV range is estimated about 4.7 J and corresponding efficiency for x-ray generation is 0.09%. The x-rays with energy >15 keV have 15–20 ns pulse duration and ∼1 mm source size. This radiation is used for contact x-ray imaging of biological and compound objects and spatial resolution of ∼50 μm is demonstrated.
Silicon-on-diamond material by pulsed laser technique
Authors: Lagomarsino S. , Parrini G. , Sciortino S. , Santoro M. , Citroni M. , Vannoni M. , Fossati A. , Gorelli F. , Molesini G. , Scorzoni A.
Published: January 2010

We present a method to bond directly silicon and diamond plates to obtain a single silicon-on-diamond material, with a carbon–silicon interface of unprecedented quality. The bonding is performed at room temperature, via picosecond 355 nm pulsed laser irradiation of the silicon-diamond interface, through the transparent diamond. The obtained material exhibits excellent mechanical strength and uniformity of the bonding, as shown by mechanical tests and analysis of the cross section based on scanning electron microscopy. The bonding is ascribed to silicon carbide nanolayers at the interface which, along with amorphous silicon nanolayers, have been quantitatively detected and evaluated by means of optical spectroscopy measurements. A physical insight into the processes occurring at the diamond-silicon interface during the pulsed irradiation and cooling has been provided by a finite element numerical model. A rationale is then given for the observed SiC bond in terms of silicon and diamond melting and inter-diffusion. A crucial outcome of the model consists in predicting the effect of the different laser beam parameters on the bonding process, thereby allowing us to obtain a well tailored procedure. An excellent quality silicon-on-diamond is now available for implementing highly integrated electronic devices for diverse application areas, ranging from pixel detectors to biosensors and prostheses for the human body.
Response to “Comment on ‘Experimental observation of carbon dioxide reduction in exhaust gas from hydrocarbon fuel burning’ ” [Phys. Plasmas 17, 014701 (2010)]
Authors: Uhm Han S. , Kim Chul H.
Published: January 2010

A high-voltage cathode initiates an electron emission, resulting in a reduction in the carbon dioxide concentration in exhaust gas from the burning of hydrocarbon fuel. Assuming that the observed carbon dioxide reduction is originated from the molecular decomposition, the energy needed for the endothermic reaction of this carbon dioxide reduction may stem primarily from the internal energy reduction in the exhaust gas in accordance of the first law of the thermodynamics. An oxygen increase due to the reduction in carbon dioxide in a discharge gas was observed in real time.
The role of dot height in determining exciton lifetimes in shallow InAs/GaAs quantum dots
Authors: Campbell-Ricketts T. E. J. , Kleemans N. A. J. M. , Nötzel R. , Silov A. Yu. , Koenraad P. M.
Published: January 2010

The spectral dependence of the photoluminescence recombination lifetime has been measured for individual self-assembled InGaAs/GaAs quantum dots, over the entire emission envelope. The measurements show a rising trend with increasing emission wavelength, increasing from 680 ps at 900 nm to about 1020 ps at 990 nm. Measurements of the out-of-plane diamagnetic coefficients for the dots show almost no correlation with wavelength. As a result, the rising trend in the lifetimes with wavelength is interpreted in terms of the emission energy being predominantly determined by the dot height, with higher dots exhibiting longer lifetimes.
Why are Mixed-Race People Perceived as more Attractive?
Authors: Lewis Michael B
Published: January 2010

Previous, small scale, studies have suggested that people of mixed race are perceived as being more attractive than non-mixed-race people. Here, it is suggested that the reason for this is the genetic process of heterosis or hybrid vigour (ie cross-bred offspring have greater genetic fitness than pure-bred offspring). A random sample of 1205 black, white, and mixed-race faces was collected. These faces were then rated for their perceived attractiveness. There was a small but highly significant effect, with mixed-race faces, on average, being perceived as more attractive. This result is seen as a perceptual demonstration of heterosis in humans—a biological process that may have implications far beyond just attractiveness.
4 Engineers of Art
Authors: Oja Carol J.
Published: January 2010

Leo Ornstein and Edgard Varèse began imagining the dimensions of American modernism during the 1910s. But on the whole, the 20th century dawned for American composers in the 1920s. This was a decade when iconoclastic ideas blasted through hallowed traditions, with machines often providing the horsepower to do so. The decade quickly became known as the “Machine Age”—a rubric that in a broader sense has been used to cover the entire interwar period. For modernist composers in the United States, the machine had two powerful manifestations: it yielded new sound sources, and it provided new means of preserving and transmitting performances. One important facet of the machine movement in modernist music was the invention of new musical instruments. In New York City, these instruments were the Theremin, the Clavilux, the Crea-tone, the Vitaphone, and the Martenot. By no means a circumscribed movement that yielded a few art works and then ended, the machine aesthetic projected outward like a beam of light, illuminating future potential and suggesting unexplored aesthetic territory.