bluuebunny/crossref_metadata_2025 huggingface dataset:
The spatial distribution of stars in open clusters
Authors: Sánchez Néstor , Alfaro Emilio J.
Published: January 2010

We study the internal spatial structure of 16 open clusters in the Milky Way spanning a wide range of ages. For this, we use the minimum-spanning-tree method (the Q parameter, which enables one to classify the stellar distribution as either radially or fractally clustered), King-profile fitting, and the correlation dimension (Dc) for those clusters with fractal patterns. On average, clusters with fractal-like structure are younger than those exhibiting radial stellar-density profiles. There is a significant correlation between Q and the cluster age measured in crossing-time units. For fractal clusters, there is a significant correlation between fractal dimension and age. These results support the idea that stars in newly born clusters likely follow the fractal patterns of their parent molecular clouds, and eventually evolve towards more centrally concentrated structures. However, stellar clusters as old as ~ 100 Myr can exist that have not totally destroyed their fractal structure. Finally, we have found the intriguing result that the lowest fractal dimensions obtained for the open clusters seem to be considerably smaller than the average value measured in Galactic molecular cloud complexes.
Refining the true parameters of the open cluster NGC 4852
Authors: Solivella Gladys , Giorg Edgard , Vázquez Rubén , Carraro Giovanni
Published: January 2010

NGC 4852 is a moderately compact cluster centered at α2000 = 13 : 00 : 09; δ = −59 : 36 : 48, located near the center of an Hα superring. This cluster forms part of an extended region including young stellar aggregates inside a circle with a radius of 3 degrees, where many show an abundance of emission line stars. In the field of this cluster, two stars of known type exist: Wray 15–1039 (emission-line object) and CD −58:4845 (emission-line star). We do not yet know whether the Be phase is transient or whether it is just what randomly happens in some hot stars. It appears that Be star may be found even in clusters as old as 70 Myr with a high occurrence rate in clusters of 25–27 Myr old. A recent photometric survey in NGC 4852 down to V = 22 – 23 mag established that NGC 4852 is about 200 – 250 Myr old, located at 1.1 kpc from the Sun and with a mean E(B − V) = 0.45 mag. Since the presence of potential Be-type stars in the cluster area suggests it may be a very young object instead of moderately old, we decided to carry out spectroscopy for 33 selected stars and CCD UBVI photometry for the bright objects in the cluster area. This way, we attempt to clarify their evolutionary state and include them in the framework of emission-line stars and open clusters. From our analysis, we agree with the cluster distance and reddening determined by earlier studies, but we derive that the age of NGC 4852 is younger than 40 Myr.
Membership status of TWA22AB
Authors: Teixeira Ramachrisna , Ducourant Christine , Chauvin Gael , Krone–Martins Alberto G. O. , Bonnefoy Mickael , Song Inseok
Published: January 2010

Using the ESO NTT/SUSI2 telescope, we observed TWA22AB during five different observing runs over 1.2 years to measure its trigonometric parallax and proper motion. HARPS at the ESO 3.6m telescope was also used to measure the system's radial velocity over 2 years. Based on trigonometric-parallax, proper-motion and radial-velocity measurements, we re-analyzed the membership of TWA22AB of the young, nearby associations TW Hydrae, β Pictoris and Tucana–Horologium.
sacy: open clusters connected to young nearby associations
Authors: Torres C. A. O. , Quast G. R. , Melo C. H. F. , Sterzik M. , de la Reza R. , da Silva Licio
Published: January 2010

In recent years. we have spectroscopically observed thousands of counterparts of selected ROSAT bright sources in the sacy project (Search for Associations Containing Young stars). We demonstrated that hundreds of the young stars found this way belong to nearby young, loose associations, some detected only in sacy, with ages in the range from 5 to 100 Myr. For their ages, these associations show no trace of their primitive nurseries, which poses some difficulties as to their origins. Nevertheless, there are some associations clearly associated with young open clusters, such as the ϵ Cha association (6 Myr) with the η Cha cluster, and the Argus association with IC 2391 (40 Myr). There seem to exist also more subtle connections, such as the AB Dor association (75 Myr) with the Pleiades. Here, we present evidence of the connections of young associations to open clusters, to understand their origin and their possible insertion in the cluster infant-mortality and Gould Belt scenarios.
Probing star formation at intermediate z
Authors: Voyer E. N. , de Mello D. F. , Quirk C. , Siana B. , Gardner J. P. , Teplitz H.
Published: January 2010

We summarize the latest results of an ongoing project aimed at connecting starburst galaxies in the local Universe and Lyman-break galaxies (LBGs) in the distant Universe using rest-frame ultraviolet (UV) images. We are quantifying star formation in the local Universe using GALEX data of interacting galaxies and we are using Hubble Space TelescopeU-band and optical images of the Ultra Deep Field to quantify star formation at intermediate (z ~ 1) and high (z > 2) redshifts, respectively. We are measuring sizes of star-forming clumps in all redshift ranges and searching for evolutionary effects. We chose the rest-frame UV to do this work because young and massive stars radiate most their energy in the UV and also because LBGs are selected to be UV-bright. We discuss whether all galaxies go through an LBG phase and whether disks show any sign of size of evolution at z < 1.
Super star clusters and their emission lines
Authors: Wünsch Richard , Palouš Jan , Tenorio–Tagle Guillermo , Silich Sergiy , Muñoz–Tuñón Casiana
Published: January 2010

Super star clusters (SSCs) are young massive objects typically observed in starburst galaxies. They consist of millions of stars occupying volumes only several parsecs across. Recent infrared observations of SSCs reveal strong emission lines with moderately supersonic widths (FWHM ~ 50 – 100 km s−1). An additional, much broader and weaker line component is present in some cases. Using 2D and 3D hydrodynamic simulations, we study models of SSCs in the so-called bimodal regime, which occurs if the stellar density inside the cluster exceeds a certain limit. We confirm the existence of the bimodal solution predicted analytically and suggest an explanation for double-component line profiles: the narrow component is formed close to the cluster center by repressurizing shocks compressing the rarefied gas cooled down due to the thermal instability into dense cold clumps, while the broad component is created by the wind, which cools down at a certain distance from the cluster.
Blue stragglers in star clusters and the conventional SSP models
Authors: Xin Yu , de Grijs Richard , Deng Licai , Kroupa Pavel
Published: January 2010

The presence of blue straggler stars (BSs) as secure members of star clusters poses a major challenge to the conventional picture of simple stellar population (SSP) models. The models are based on the stellar evolution theory of single stars, while the major formation mechanisms of BSs are all correlated with stellar interactions. Based on a sufficient working sample including 100 Galactic open clusters, one Galactic globular cluster, and seven Magellanic Cloud star clusters, we discuss the modifications of the properties of broad-band colors and Lick indices of the standard SSP models due to BS populations.
IC 361, a distant intermediate-age cluster in Camelopardalis
Authors: Zdanavičius Justas , Boyle Richard P. , Vrba Frederick J. , Zdanavičius Kazimieras , Bartašiūtė Stanislava
Published: January 2010

We have undertaken CCD photometry in the eight-color Vilnius + I system for the open cluster IC 361 (l = 147.5°, b = 5.7°) located in the constellation of Camelopardalis. Based on multicolor data, estimates of distance moduli, foreground reddening and metallicity have been obtained for individual stars measured in the field of the cluster. This allowed us to eliminate most of the field stars and to identify the probable cluster members, from which we derived the true distance modulus (m − M)0 = 12.7 mag and metallicity [Fe/H] = −0.3 dex. The interstellar extinction is found to be nonuniform across the field, with values of AV ranging from 1.9 to 2.6 mag. A comparison of the color–magnitude diagrams with Padova isochrones yields (m − M)0 = 12.6 mag, or a cluster distance of 3.3 kpc, and an age of 1.0 Gyr. Therefore, IC 361 appears to be a mildly metal-deficient cluster of intermediate age, located as far as, or just beyond, the Perseus spiral arm.
The globular cluster NGC 5286: color–magnitude diagram and variable stars
Authors: Zorotovic M. , Catelan M. , Zoccali M. , Smith H. A. , Pritzl B. J.
Published: January 2010

We present BV photometry and the results of a search for stellar variability in the globular cluster NGC 5286, which has tentatively been associated with the Canis Major dwarf spheroidal galaxy. Our results indicate an Oosterhoff type II for the cluster, which is unusual for an object of extragalactic origin.
An RF spectrometer for fast wide band measurement
Authors: Hemour Simon , Podevin Florence , Xavier Pascal
Published: January 2010

A new type of spectrum analyzer using RF interferometry is presented. The stationary wave integrated Fourier transform spectrometer is dedicated to the measurement of transient wideband signals. The spectrometer is mobile and cheap. It consists of spatial samplers placed along a waveguide ended by a short circuit. The standing wave caused by the short circuit is sampled and the spectrum is obtained by an FFT computation. A 0.3–5 GHz analyzer was built as a proof-of-principle demonstration and an application to RF dosimetry is shown.
Duration, magnitude, and frequency of subaerial volcano deformation events: New results from Latin America using InSAR and a global synthesis
Authors: Fournier T. J. , Pritchard M. E. , Riddick S. N.
Published: January 2010

We combine new observations of volcano deformation in Latin America with more than 100 previous deformation studies in other areas of the world to constrain the frequency, magnitude, and duration of subaerial volcano deformation events. We discuss implications for eruptive hazards from a given deformation event and the optimum repeat interval for proposed InSAR satellite missions. We use L band (23.6 cm wavelength) satellite‐based interferometric synthetic aperture radar (InSAR) to make the first systematic search for deformation in all volcanic arcs of Latin America (including Mexico, Central America, the Caribbean, and the northern and southern Andes), spanning 2006–2008. We combine L and C band (5.6 cm wavelength) InSAR observations over the southern Andes volcanoes to extend the time series from 2002 to 2008 and assess the capabilities of the different radars: L band gives superior results in highly vegetated areas. Our observations reveal 11 areas of volcano deformation, some of them in areas that were thought to be dormant. There is a lack of observed deformation at several erupting volcanoes, probably due to temporal aliasing. The total number of deforming volcanoes in the central and southern Andes now totals 15 (from observations between 1992 and 2008), comparable to the Alaska/Aleutian arc. Globally, volcanoes deform across a variety of time scales (from seconds to centuries) often without eruption and with no apparent critical observation time scale, although observations made every minute are sometimes necessary to see precursors to eruption.
Magnetic susceptibility as a tool to study deformed calcite with variable impurity content
Authors: Almqvist Bjarne S. G. , Herwegh Marco , Schmidt Volkmar , Pettke Thomas , Hirt Ann M.
Published: January 2010

A set of calcite mylonites were systematically sampled along the basal shear zone of the Morcles Nappe, located in the southwestern Swiss Alps, to investigate the relationship among crystallographic preferred orientation (CPO), chemistry, and anisotropy of magnetic susceptibility (AMS). Second‐phase minerals are ≤10 vol % of the rock. The substitution of trace impurities for Ca in the calcite crystal lattice, in particular, Fe, Mn, Mg, and Sr, varies among the samples with total values ranging from 1450 ± 190 ppm in the most pure sample to 2450 ± 320 ppm for the most impure sample. Fe shows the largest variation among the sample group and varies by a factor of nearly four from the purest (230 ± 30 ppm) to the most impure sample (840 ± 110 ppm). All samples have negative bulk susceptibility, and the concentration of ferromagnetic (in a broad sense) phases is very low. A correlation is identified between trace element chemistry, CPO of calcite, and the magnetic susceptibility. The bulk susceptibility and the AMS vary systematically with Fe and Mn elemental concentration in the matrix calcite, and this variation is apparent for the entire length of the shear zone. A simple model that takes into account the CPO and trace element chemistry is used to explain the resulting bulk susceptibility and AMS. Calcite mylonites and marbles from other locations fit the model, indicative of a general relationship between CPO, chemistry, and AMS in calcites where second‐phase minerals are sparse. For lithologies that are dominated magnetically by calcite, with a deficiency of secondary phases, magnetic susceptibility can be used to rapidly screen rock samples for the variation of paramagnetic trace elements Fe and Mn and CPO, which can then be used for detailed microfabric studies.
Spatial variations of effective moisture in the western United States
Authors: Shinker Jacqueline J. , Bartlein Patrick J.
Published: January 2010

Spatial patterns of actual evapotranspiration (AE), potential evapotranspiration (PE), and their ratio (AE/PE) in the western United States are examined to describe the annual cycle of moisture availability. Long‐term (1971–2000) averages of observed temperature and precipitation, and sunshine data were used to calculate AE and PE. A cluster analysis identifies regions with similar annual cycles of AE/PE. We identify three different spatial scales of variability in AE/PE: (1) broadscale patterns reflect the trade‐off between winter‐dominated precipitation of the Pacific Northwest and summer‐dominated precipitation east of the Rocky Mountains, and the south‐to‐north decrease in PE related to latitudinal variations in net radiation; (2) mesoscale patterns show the influence of regional‐scale features (e.g., the North American Monsoon); and (3) local‐scale patterns are related to topography. Understanding the scales of effective‐moisture variations is valuable from the perspective of terrestrial ecosystems and water resources management in the mostly arid western United States.
Isentropic modeling of a cirrus cloud event observed in the midlatitude upper troposphere and lower stratosphere
Authors: Montoux N. , Keckhut P. , Hauchecorne A. , Jumelet J. , Brogniez H. , David C.
Published: January 2010

This publication provides a detailed study of one cirrus cloud observed by lidar at the Observatory of Haute‐Provence (∼44°N) in January 2006 in the vicinity of the tropopause (12–14 km/∼136–190 hPa/328–355 K). The higher part of the air mass observed comes from the wet subtropics while the lower part comes from the midlatitudes. Both are advected by the Azores anticyclone, encounter cold temperatures (∼205 K) above the North Atlantic Ocean, and flow eastward along the anticyclonic flank of the polar jet stream. A simulation of this cloud by an isentropic model is tested to see if synoptic‐scale atmospheric structures could explain by itself the presence of such clouds. The developments made in the Modélisation Isentrope du transport Méso‐échelle de l'Ozone Stratosphérique par Advection (MIMOSA) model to take into account the three phases of water and their interactions allow reproduction of the occurrence of the cirrus and its temporal evolution. MIMOSA‐H2O reproduces the atmospheric water vapor structures observed with Atmospheric Infrared Sounder (AIRS) with, however, an apparent wet bias of around 50%. Reliable water vapor fields appear to be the main condition to correctly simulate such cirrus clouds. The model reproduces the cirrus cloud altitude for fall speeds around 1 cm/s and gives ice water content around 3–4 mg/m3. Fall speed is also a critical parameter, and a better parameterization with altitude or other atmospheric conditions in the modeling of such cirrus clouds is required. This study also shows that supersaturation threshold impacts strongly the vertical and horizontal extension of the cirrus cloud but more slightly the ice water path.
Mixing and water‐soluble characteristics of particulate organic compounds in individual urban aerosol particles
Authors: Li Weijun , Shao Longyi
Published: January 2010

Particulate organic compounds (POCs) in the atmosphere can alter the morphology and hygroscopicity of inorganic particles by coagulation and mixing. Direct observations can illustrate the mixing of organic and inorganic particles. Compositions, mixing states, and morphologies of 360 aerosol particles from urban Beijing collected on transmission electron microscopy (TEM) grids with Si‐O substrate were obtained using TEM coupled with energy‐dispersive X ray spectrometry (TEM/EDX). The Si‐O substrate used in this study allows TEM/EDX to detect carbonaceous particles internally mixed with inorganic particles. POCs were present in approximately 90% of the nitrate‐coated mineral particles on both hazy and clear days. Approximately 73% of K‐ and S‐rich particles contained organic coatings and organic inclusions/aggregations on hazy days, while 53% of S‐rich particles on clear days during the Beijing Olympics contained only organic coatings. Water dialysis of individual particles indicated that the organic inclusions/aggregations in the K‐ and S‐rich particles were insoluble in water but that POCs from the coatings of individual particles were soluble. The organic coatings on individual inorganic particles may influence their surface hygroscopicity and optical properties.
A numerical model for the coupled long‐term evolution of salt marshes and tidal flats
Authors: Mariotti Giulio , Fagherazzi Sergio
Published: January 2010

A one‐dimensional numerical model for the coupled long‐term evolution of salt marshes and tidal flats is presented. The model framework includes tidal currents, wind waves, sediment erosion, and deposition, as well as the effect of vegetation on sediment dynamics. The model is used to explore the evolution of the marsh boundary under different scenarios of sediment supply and sea level rise. Numerical results show that vegetation determines the rate of marsh progradation and regression and plays a critical role in the redistribution of sediments within the intertidal area. Simulations indicate that the scarp between salt marsh and tidal flat is a distinctive feature of marsh retreat. For a given sediment supply the marsh can prograde or erode as a function of sea level rise. A low rate of sea level rise reduces the depth of the tidal flat increasing wave dissipation. Sediment deposition is thus favored, and the marsh boundary progrades. A high rate of sea level rise leads to a deeper tidal flat and therefore higher waves that erode the marsh boundary, leading to erosion. When the rate of sea level rise is too high the entire marsh drowns and is transformed into a tidal flat.
Concepts in Toxicology
Authors: Duffus John H , Templeton Douglas M , Nordberg Monica ,   IUPAC, Lorimer John W
Published: January 2010

Toxicology has never been more important. Advances in chemistry and technology offering improvements in the quality of human life become ever more rapid, bringing with them the potential for new toxicity hazards. This has led to legislation requiring toxicity testing and risk assessment for all chemicals and their uses. The new REACH (Risk Evaluation and Authorization of Chemicals) Regulation has profound economic consequences because, without official authorization, a chemical cannot be marketed. This book explains, in depth, the ideas underlying current advances in toxicology and its application in regulating and ensuring the safe use of chemicals. Sometimes old ideas have become assumptions that have become embedded in related laws and regulation, even though the thinking of toxicologists has moved on in line with developments in science. This leads to confusion in public understanding that the book should dispel. There are also fundamental ideas in toxicology that are not well understood concerning the concepts of hazard and risk and even about what constitutes a chemical. For many people the word 'chemical' describes manmade substances only. In fact, it is correctly applied to all substances that exist, from pure elements to the most complex biological molecules in food and medicines. This is further complicated by the complex distinction between the descriptors, 'toxic' and 'nontoxic'. Developments in epigenetics are revolutionizing our understanding of mutagenicity and carcinogenicity. Improved understanding of apoptosis and necrosis leads to improved interpretation of potentially toxic effects at the cellular level. The recently defined term 'chemical speciation' is driving more targeted research on the toxicity of inorganic chemicals. This book explains the concepts implied by key toxicological terms using diagrams to illustrate the relationships between them. It is an essential aid to understanding the new demands from regulators of risk assessment and to the implementation of appropriate risk management.
Successive catalytic reactions specific to Pd-based rotaxane complexes as a result of wheel translation along the axle
Authors: Miyagawa Norihito , Watanabe Masahiro , Matsuyama Takanori , Koyama Yasuhito , Moriuchi Toshiyuki , Hirao Toshikazu , Furusho Yoshio , Takata Toshikazu
Published: January 2010

Rotaxane-structure-specific Pd-catalyzed rearrangement of propargyl urethane or allyl urethane groups to 2-oxazolidone or oxazolidinone moieties proceeded efficiently.
Synthesis of delaminated LDH: A facile two step approach
Authors: Antonyraj Churchil A. , Koilraj P. , Kannan S.
Published: January 2010

One-step synthesis of carbonate-free nitrate containing LDHs was achieved using hexamine hydrolysis at low temperature and the products were delaminated successfully in water; materials showed total delamination in formamide while restacking behavior depended critically on the medium.
Amphiphilic block copolymer nano-fibers via RAFT-mediated polymerization in aqueous dispersed system
Authors: Boissé Stéphanie , Rieger Jutta , Belal Khaled , Di-Cicco Aurélie , Beaunier Patricia , Li Min-Hui , Charleux Bernadette
Published: January 2010

Various morphologies, in particular long fibers, were formed via RAFT-mediated polymerization of styrene in aqueous emulsion in the presence of a water-soluble macromolecular RAFT agent based on acrylic acid and PEG-acrylate.
A chiral diphosphine as trans-chelate ligand and its relevance to catalysis
Authors: Nasser Nasser , Eisler Dana J. , Puddephatt Richard J.
Published: January 2010

A chiral diphosphine ligand gives fluxional trans-chelate complexes with gold(i) and silver(i), and they are useful models for catalytic intermediates.
Pressure-induced Jahn–Teller switching in a Mn12 nanomagnet
Authors: Parois Pascal , Moggach Stephen A. , Sanchez-Benitez Javier , Kamenev Konstantin V. , Lennie Alistair R. , Warren John E. , Brechin Euan K. , Parsons Simon , Murrie Mark
Published: January 2010

Using high pressure diffraction and magnetic data, we observe reversible switching of a Mn12 nanomagnet from the 100% fast-relaxing species to the 100% slow-relaxing species, by flipping the misaligned Jahn–Teller axis.
Intracellular aggregation of human stefin B: confocal and electron microscopy study
Authors: Čeru Slavko , Layfield Robert , Zavašnik‐Bergant Tina , Repnik Urška , Kopitar‐Jerala Nataša , Turk Vito , Žerovnik Eva
Published: January 2010

Background. Protein aggregation is a major contributor to the pathogenic mechanisms of human neurodegenerative diseases. Mutations in the CSTB (cystatin B) gene [StB (stefin B)] cause EPM1 (progressive myoclonus epilepsy of type 1), an epilepsy syndrome with features of neurodegeneration and increased oxidative stress. Oligomerization and aggregation of StB in mammalian cells have recently been reported. It has also been observed that StB is overexpressed after seizures and in certain neurodegenerative conditions, which could potentially lead to its aggregation. Human StB proved to be a good model system to study amyloid fibril formation in vitro and, as we show here, to study protein aggregation in cells.

Results. Endogenous human StB formed smaller, occasional cytoplasmic aggregates and chemical inhibition of the UPS (ubiquitin–proteasome system) led to an increase in the amount of the endogenous protein and also increased its aggregation. Further, we characterized both the untagged and T‐Sapphire‐tagged StB on overexpression in mammalian cells. Compared with wild‐type StB, the EPM1 missense mutant (G4R), the aggregate‐prone EPM1 mutant (R68X) and the Y31 StB variant (both tagged and untagged) formed larger cytosolic and often perinuclear aggregates accompanied by cytoskeletal reorganization. Non‐homogeneous morphology of these large aggregates was revealed using TEM (transmission electron microscopy) with StB detected by immunogold labelling. StB‐positive cytoplasmic aggregates were partially co‐localized with ubiquitin, proteasome subunits S20 and S26 and components of microfilament and microtubular cytoskeleton using confocal microscopy. StB aggregates also co‐localized with LC3 and the protein adaptor p62, markers of autophagy. Flow cytometry showed that protein aggregation was associated with reduced cell viability.

Conclusions. We have shown that endogenous StB aggregates within cells, and that aggregation is increased upon protein overexpression or proteasome inhibition. From confocal and TEM analyses, we conclude that aggregates of StB show some of the molecular characteristics of aggresomes and may be eliminated from the cell by autophagy. Intracellular StB aggregation shows a negative correlation with cell survival.
Thyroid hormones regulate phosphate homoeostasis through transcriptional control of the renal type IIa sodium-dependent phosphate co-transporter (Npt2a) gene
Authors: Ishiguro Mariko , Yamamoto Hironori , Masuda Masashi , Kozai Mina , Takei Yuichiro , Tanaka Sarasa , Sato Tadatoshi , Segawa Hiroko , Taketani Yutaka , Arai Hidekazu , Miyamoto Ken-ichi , Takeda Eiji
Published: January 2010

The type IIa renal sodium-dependent phosphate (Na/Pi) co-transporter Npt2a is implicated in the control of serum phosphate levels. It has been demonstrated previously that renal Npt2a protein and its mRNA expression are both up-regulated by the thyroid hormone T3 (3,3′,5-tri-iodothyronine) in rats. However, it has never been established whether the induction was mediated by a direct effect of thyroid hormones on the Npt2a promoter. To address the role of Npt2a in T3-dependent regulation of phosphate homoeostasis and to identify the molecular mechanisms by which thyroid hormones modulate Npt2a gene expression, mice were rendered pharmacologically hypo- and hyper-thyroid. Hypothyroid mice showed low levels of serum phosphate and a marked decrease in renal Npt2a protein abundance. Importantly, we also showed that Npt2a-deficient mice had impaired serum phosphate responsiveness to T3 compared with wild-type mice. Promoter analysis with a luciferase assay revealed that the transcriptional activity of a reporter gene containing the Npt2a promoter and intron 1 was dependent upon TRs (thyroid hormone receptors) and specifically increased by T3 in renal cells. Deletion analysis and EMSAs (electrophoretic mobility-shift assays) determined that there were unique TREs (thyroid-hormone-responsive elements) within intron 1 of the Npt2a gene. These results suggest that Npt2a plays a critical role as a T3-target gene, to control phosphate homoeostasis, and that T3 transcriptionally activates the Npt2a gene via TRs in a renal cell-specific manner.
Angiotensin II infusion promotes ascending aortic aneurysms: attenuation by CCR2 deficiency in apoE−/− mice
Authors: Daugherty Alan , Rateri Debra L. , Charo Israel F. , Owens A. Phillip , Howatt Deborah A. , Cassis Lisa A.
Published: January 2010

AngII (angiotensin II) induces atherosclerosis and AAAs (abdominal aortic aneurysms) through multiple proposed mechanisms, including chemotaxis. Therefore, we determined the effects of whole-body deficiency of the chemokine receptor CCR2 (CC chemokine receptor 2) on these diseases. To meet this objective, apoE (apolipoprotein E)−/− mice that were either CCR2+/+ or CCR2−/−, were infused with either saline or AngII (1000 ng·kg−1 of body weight·min−1) for 28 days via mini-osmotic pumps. Deficiency of CCR2 markedly attenuated both atherosclerosis and AAAs, unrelated to systolic blood pressure or plasma cholesterol concentrations. During the course of the present study, we also observed that AngII infusion led to large dilatations that were restricted to the ascending aortic region of apoE−/− mice. The aortic media in most of the dilated area was thickened. In regions of medial thickening, distinct elastin layers were discernable. There was an expansion of the distance between elastin layers in a gradient from the intimal to the adventitial aspect of the media. This pathology differed in a circumscribed area of the anterior region of ascending aortas in which elastin breaks were focal and almost transmural. All regions of the ascending aorta of AngII-infused mice had diffuse medial macrophage accumulation. Deficiency of CCR2 greatly attenuated the AngII-induced lumen dilatation in the ascending aorta. This new model of ascending aortic aneurysms has pathology that differs markedly from AngII-induced atherosclerosis or AAAs, but all vascular pathologies were attenuated by CCR2 deficiency.
From Planning Support Systems to Mediated Planning Support: A Structured Dialogue to Overcome the Implementation Gap
Authors: Brömmelstroet Marco Te , Schrijnen Pieter M
Published: January 2010

Planning support systems (PSSs) are intended to facilitate relevant steps in planning processes; however, the academic evaluation of PSSs reveals many bottlenecks precluding a widespread use of these systems. A central weakness is the lack of communication between PSS developers (focusing on technical issues) and potential PSS users. Other academic fields such as knowledge management and technological innovation recognised similar bottlenecks years ago. On the basis of methods proposed in these fields, a new process architecture for the development of a PSS is proposed. Through a dialogue in which PSS developers and potential users discuss and use the PSS, existing tools, instruments, and models are refined and improved to be more useful to their potential users. The focus shifts away from the development of a technically more sophisticated support system, towards a process of PSS development which is intertwined with the planning process itself. This process architecture is called mediated planning support (MPS). We explore what can be learned from other academic domains and enquire about the applicability of these findings to PSS development. In Amsterdam the Department of Transport wanted to transform their transportation model into a land-use and transport PSS and their work illustrates how such a process architecture can link PSS developers and users in planning practice. We discuss the concepts behind MPS and use the case of Amsterdam to visualise its workings, lastly offering hypotheses on the method and suggestions for further research.
Visual Analogy, Visual Displays, and the Nature of Design Problems: The Effect of Expertise
Authors: Casakin Hernan
Published: January 2010

Analogy is a powerful heuristic for problem solving. In design, where designers are constantly exposed to visual stimuli, visual analogies are considered to be particularly helpful. To date, however, few researchers have given enough attention to visual analogy and visual displays in design contexts. This study deals with the use of these tools by investigating the effect that expertise has on them, in ill-defined and well-defined problem solving. Novice and experienced designers solved both types of design problem with exposure to visual displays and with the requirement to use visual analogy. Results showed that when visual displays and instructions to use analogy were available no expertise differences existed in well-defined problem solving. However, with the availability of only visual displays, architects tend to perform better than students. Without guidance to use analogy, students found difficulty in spontaneous recall of visual displays as candidate analogues in well-defined problems. In ill-defined problem solving, architects performed better than novice students in the use of both analogy and visual displays. However, no differences were found between the experienced designers and the advanced students in any experimental condition in this problem context.
Fiona Powrie: Gut diplomacy
Authors: Maxmen Amy
Published: January 2010

Fiona Powrie seeks to regain the peace that's been disrupted in patients with inflammatory bowel disease.
Prevalence and natural history of heart disease in adults with primary mitochondrial respiratory chain disease
Authors: Limongelli Giuseppe , Tome‐Esteban Maite , Dejthevaporn Charungthai , Rahman Shamima , Hanna Michael G. , Elliott Perry M.
Published: January 2010

Aims

The prevalence and natural history of cardiovascular disease in adult patients with respiratory chain disease (RCD) is poorly characterized. We sought to determine the frequency and natural history of cardiac disease in patients with primary RCD.

Methods and results

Thirty‐two patients (37.8 ± 12.6 years) with a definite diagnosis of RCD underwent clinical examination, electrocardiography (ECG), 24 h Holter ECG, and cardiopulmonary exercise testing. Patients were classified into six different phenotypes: mitochondrial myopathy (MM; n = 8), chronic progressive ophthalmoplegia (CPEO; n = 2), chronic progressive ophthalmoplegia with myopathy (CPEO + MM; n = 12), Kearns–Sayre syndrome (KSS; n = 2), mitochondrial encephalopathy with lactic acidosis and stroke‐like episodes (MELAS; n = 7), neuropathy, ataxia, and retinitis pigmentosa (NARP; n = 1). Twenty‐two patients (69%) had a mitochondrial DNA mutation. Twenty‐six patients (81%) had evidence for cardiac involvement: ECG abnormalities (69%) and cardiomyopathy (hypertrophic 19%; restrictive 3%; left ventricular non‐compaction 3%). During follow‐up (4.1 ± 2.8 years), two patients with CPEO + MM developed hypertrophic cardiomyopathy and one patient with NARP developed peripartum dilated cardiomyopathy. Four patients (KSS = 2; MM = 1; MELAS = 1) developed arrhythmias or syncope requiring device therapy or invasive procedures. One patient with MM and cardiomyopathy had an orthotopic heart transplant. One patient with CPEO + MM died from respiratory failure. Freedom from all cardiovascular events at 5 years was 67% (95% CI 47.4–86.6).

Conclusion

All patients with RCD should undergo careful and repeated clinical assessment to diagnose and manage cardiovascular involvement. However, life‐threatening cardiovascular complications rarely occur, and the prognosis is generally favourable.
Functional effects of glucose transporters in human ventricular myocardium
Authors: von Lewinski Dirk , Gasser Robert , Rainer Peter P. , Huber Marie‐Sophie , Wilhelm Bastian , Roessl Ulrich , Haas Tobias , Wasler Andrae , Grimm Michael , Bisping Egbert , Pieske Burkert
Published: January 2010

Aims

Insulin‐dependent positive inotropic effects (PIE) are partially Ca2+ independent. This mechanism is potentially glucose dependent. In contrast to most animal species, human myocardium expresses high levels of sodium‐glucose‐transporter‐1 (SGLT‐1) mRNA besides the common glucose‐transporters‐1 and ‐4 (GLUT1, GLUT4).

Methods and results

We used ventricular myocardium from 61 end‐stage failing human hearts (ischaemic cardiomyopathy, ICM and dilated cardiomyopathy, DCM) and 13 non‐failing donor hearts. The effect of insulin on isometric twitch force was examined with or without blocking of PI3‐kinase, GLUT4‐translocation, or SGLT‐1. Substrate‐dependent (glucose vs. pyruvate vs. palmitoyl‐carnitine) effects were tested in atrial myocardium. mRNA expression of glucose transporters was analysed. Insulin increased developed force by 122 ± 7.4, 121.7 ± 2.5, and 134.1 ± 5.7% in non‐failing, DCM, and ICM (P < 0.05 vs. DCM), respectively. Positive inotropic effect was partially blunted by inhibition of PI‐3‐kinase, GLUT4, or SGLT1. Combined inhibition of PI3‐kinase and glucose‐transport completely abolished PIE. Positive inotropic effect was significantly stronger in glucose‐containing solution compared with pyruvate or palmitoyl‐carnitine containing. mRNA expression showed only a tendency towards elevated GLUT4‐expression in ICM.

Conclusions

Positive inotropic effect of insulin is pronounced in ICM, but underlying mechanisms are unaltered. The Ca2+‐independent PIE of insulin is mediated via glucose‐transporters. Together with the Ca2+‐dependent PI‐3‐kinase mediated pathway, it is responsible for the entire PIE. Substrate‐dependency affirms a glucose‐dependent part of the PIE.
The relationship between systolic blood pressure on admission and mortality in older patients with heart failure
Authors: Vidán María T. , Bueno Héctor , Wang Yongfei , Schreiner Geoffrey , Ross Joseph S. , Chen Jersey , Krumholz Harlan M.
Published: January 2010

Aims

To determine the relationship between admission systolic blood pressure (SBP) and mortality in older patients hospitalized for heart failure (HF) and among various subgroups.

Methods and results

We evaluated the independent association between initial SBP and 30‐day and 1‐year mortality, and potential interactions by age, gender, race, previous hypertension, and left ventricular dysfunction using multivariable logistic regression in the National Heart Failure Project, a database of Medicare patients >65 years old recruited from 1998 through 2001. Among 56 942 patients, mean admission SBP was 147.0 ± 92.3 mmHg, 15% presenting with SBP >180 mmHg. Systolic blood pressure showed an inverse relationship with 30‐day and 1‐year mortality rates in all subgroups analysed. Using admission SBP of 120–149 mmHg as the reference, the adjusted odds ratios (95% confidence intervals) for 1‐year mortality were 2.18 (1.77–2.69) for SBP <90 mmHg, 1.57 (1.47–1.69) for SBP 90–119 mmHg, 0.71 (0.67–0.76) for SBP 150–179 mmHg, 0.63 (0.57–0.68) for SBP 180–209 mmHg, and 0.51 (0.44–0.59) for SBP ≥210 mmHg.

Conclusion

Higher SBP on admission is associated with significant lower 30‐day and 1‐year mortality in patients hospitalized for HF. The relationship is strong, graded, independent of other clinical factors and consistent among subgroups.
Clinical trials update from the American Heart Association meeting 2009: HEAAL, FAIR‐HF, J‐CHF, HeartMate II, PACE and a meta‐analysis of dose‐ranging studies of beta‐blockers in heart failure
Authors: Cleland John G.F. , Coletta Alison P. , Freemantle Nick , Ahmed Daniyal , Rubis Pawel , Clark Andrew L.
Published: January 2010

This article provides information and a commentary on trials relevant to the pathophysiology, prevention, and treatment of heart failure presented at the annual meeting of the American Heart Association held in Orlando, Florida in 2009. Unpublished reports should be considered as preliminary, as analyses may change in the final publication. Patients with heart failure randomized to high‐dose losartan treatment (150 mg) in the HEAAL study had a reduced risk of death or heart failure hospitalization compared with patients in the low‐dose (50 mg) group. In FAIR‐HF, patients with heart failure and concomitant iron deficiency but without severe anaemia who received iron supplementation therapy demonstrated an improvement in symptoms at 24 weeks compared with placebo. The J‐CHF study was too small and was stopped too early to provide definitive evidence about the optimal dose of carvedilol for Japanese patients with heart failure. Results from the HeartMate II study suggest that continuous‐flow left ventricular assist devices may offer benefits over pulsatile‐flow devices for long‐term support in patients with advanced heart failure. In the PACE study, atrial synchronized right ventricular pacing induced adverse effects on left ventricular function compared with atrial synchronized biventricular pacing in patients with standard pacing indications and a normal ejection fraction.
A revolution in star cluster research: setting the scene
Authors: de Grijs Richard
Published: January 2010

Star clusters and their stellar populations play a significant role in the context of galaxy evolution, across space (from local to high redshift) and time (from currently forming to fossil remnants). We are now within reach of answering a number of fundamental questions that will have a significant impact on our understanding of key open issues in contemporary astrophysics, ranging from the formation, assembly and evolution of galaxies to the details of the star-formation process. Our improved understanding of the physics driving star cluster formation and evolution has led to the emergence of crucial new open questions that will most probably be tackled in a systematic way in the next decade.
Young and intermediate-age massive star clusters
Authors: Larsen Søren S.
Published: January 2010

An overview of our current understanding of the formation and evolution of star clusters is given, with the main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within a few million years and, depending on the efficiency of star formation, the clusters may disperse almost immediately or remain gravitationally bound. Current evidence suggests that a small percentage of star formation occurs in clusters that remain bound, although it is not yet clear whether this fraction is truly universal. Internal two-body relaxation and external shocks will lead to further, gradual dissolution on time scales of up to a few hundred million years for low-mass open clusters in the Milky Way, while the most massive clusters (>105 M⊙) have lifetimes comparable to or exceeding the age of the Universe. The low-mass end of the initial cluster mass function is well approximated by a power-law distribution,, but there is mounting evidence that quiescent spiral discs form relatively few clusters with massesM>2×105 M⊙. In starburst galaxies and old globular cluster systems, this limit appears to be higher, at least several ×106 M⊙. The difference is likely related to the higher gas densities and pressures in starburst galaxies, which allow denser, more massive giant molecular clouds to form. Low-mass clusters may thus trace star formation quite universally, while the more long-lived, massive clusters appear to form preferentially in the context of violent star formation.
Massive star clusters in galaxies
Authors: Harris William E.
Published: January 2010

The ensemble of all star clusters in a galaxy constitutes its
star cluster system
. In this review, the focus of the discussion is on the ability of star clusters, particularly the systems of old massive globular clusters (GCs), to mark the early evolutionary history of galaxies. I review current themes and key findings in GC research, and highlight some of the outstanding questions that are emerging from recent work.
Star clusters as laboratories for stellar and dynamical evolution
Authors: Kalirai Jason S. , Richer Harvey B.
Published: January 2010

Open and globular star clusters have served as benchmarks for the study of stellar evolution owing to their supposed nature as simple stellar populations of the same age and metallicity. After a brief review of some of the pioneering work that established the importance of imaging stars in these systems, we focus on several recent studies that have challenged our fundamental picture of star clusters. These new studies indicate that star clusters can very well harbour multiple stellar populations, possibly formed through self-enrichment processes from the first-generation stars that evolved through post-main-sequence evolutionary phases. Correctly interpreting stellar evolution in such systems is tied to our understanding of both chemical-enrichment mechanisms, including stellar mass loss along the giant branches, and the dynamical state of the cluster. We illustrate recent imaging, spectroscopic and theoretical studies that have begun to shed new light on the evolutionary processes that occur within star clusters.
Chemical evolution of star clusters
Authors: van Loon Jacco Th.
Published: January 2010

I discuss the chemical evolution of star clusters, with emphasis on old Galactic globular clusters (GCs), in relation to their formation histories. GCs are clearly formed in a complex fashion, under markedly different conditions from any younger clusters presently known. Those special conditions must be linked to the early formation epoch of the Galaxy and must not have occurred since. While a link to the formation of GCs in dwarf galaxies has been suggested, present-day dwarf galaxies are not representative of the gravitational potential wells within which the GCs formed. Instead, a formation deep within the proto-Galaxy or within dark-matter mini-haloes might be favoured. Not all GCs may have formed and evolved similarly. In particular, we may need to distinguish Galactic Halo from Galactic Bulge clusters.
Star cluster dynamics
Authors: Vesperini Enrico
Published: January 2010

Dynamical evolution plays a key role in shaping the current properties of star clusters and star cluster systems. A detailed understanding of the effects of evolutionary processes is essential to be able to disentangle the properties that result from dynamical evolution from those imprinted at the time of cluster formation. In this review, I focus my attention on globular clusters, and review the main physical ingredients driving their early and long-term evolution, describe the possible evolutionary routes and show how cluster structure and stellar content are affected by dynamical evolution.
Genotype–phenotype mapping and the end of the ‘genes as blueprint’ metaphor
Authors: Pigliucci Massimo
Published: January 2010

In a now classic paper published in 1991, Alberch introduced the concept of genotype–phenotype (G→P) mapping to provide a framework for a more sophisticated discussion of the integration between genetics and developmental biology that was then available. The advent of evo-devo first and of the genomic era later would seem to have superseded talk of transitions in phenotypic space and the like, central to Alberch's approach. On the contrary, this paper shows that recent empirical and theoretical advances have only sharpened the need for a different conceptual treatment of how phenotypes are produced. Old-fashioned metaphors like genetic blueprint and genetic programme are not only woefully inadequate but positively misleading about the nature of G→P, and are being replaced by an algorithmic approach emerging from the study of a variety of actual G→P maps. These include RNA folding, protein function and the study of evolvable software. Some generalities are emerging from these disparate fields of analysis, and I suggest that the concept of ‘developmental encoding’ (as opposed to the classical one of genetic encoding) provides a promising computational–theoretical underpinning to coherently integrate ideas on evolvability, modularity and robustness and foster a fruitful framing of the G→P mapping problem.