bluuebunny/crossref_metadata_2025 huggingface dataset:
Agency, Affect, and the Immunological Politics of Disaster Resilience
Authors: Grove Kevin
Published: March 2014

Resilience has become a foundational component within disaster management policy frameworks concerned with building ‘cultures of safety’ among vulnerable populations. These attempts at social engineering are justified through a discourse of agency and empowerment, in which resilience programming is said to enable marginalized groups to become self-sufficient and manage their own vulnerabilities. This paper seeks to destabilize this political imaginary through a critical analysis of participatory disaster resilience programming in Jamaica. Drawing on ethnographic fieldwork conducted with Jamaica's national disaster management agency, I argue that resilience operates through an affective economy of fear, hope, and confidence that enacts an immunitary biopolitics. The object of this biopolitics is excess adaptive capacity that results from affective relations between participants and their socioecological milieu. Participatory techniques such as transect walks, focus groups, and education programs attempt to encode and manipulate these affective relations in order to construct an artificial and depoliticized form of adaptive capacity that does not threaten neoliberal order. Recognizing the immunological logic at the heart of disaster resilience opens up new ethical and political imperatives in disaster management that value adaptive capacity as the vital force of new socioecological futures, rather than as an object of governmental intervention and control.
Self-Reliance beyond Neoliberalism: Rethinking Autonomy at the Edges of Empire
Authors: Hébert Karen , Mincyte Diana
Published: March 2014

Across scholarly and popular accounts, self-reliance is often interpreted as either the embodiment of individual entrepreneurialism, as celebrated by neoliberal designs, or the basis for communitarian localism, increasingly imagined as central to environmental and social sustainability. In both cases, self-reliance is framed as an antidote to the failures of larger state institutions or market economies. This paper offers a different framework for understanding self-reliance by linking insights drawn from agrarian studies to current debates on alternative economies. Through an examination of the social worlds of semisubsistence producers in peripheral zones in the Global North, we show how everyday forms of self-reliance are mutually constituted with states and markets, particularly through interactions with labor institutions and hybrid property regimes linking individual and collective interests. We draw on empirical data from two ethnographic case studies connected by a shared colonial history and continuing local mythologies of frontier self-sufficiency: salmon fisheries in rural Alaska in the US, and agrofood economies in socialist and postsocialist Lithuania. In each site we find that although local expressions of self-reliance diverge in critical respects from neoliberal visions, these forms of everyday autonomy are nevertheless enlisted to promote market liberalization, ultimately threatening the very conditions that have long sustained semisubsistence producers' self-reliance in the first place.
Trend analysis of medium- and coarse-resolution time series image data for burned area mapping in a Mediterranean ecosystem
Authors: Katagis Thomas , Gitas Ioannis Z. , Toukiloglou Pericles , Veraverbeke Sander , Goossens Rudi
Published: March 2014

In this study, the Breaks for Additive Seasonal and Trend (BFAST), a recently introduced trend analysis technique, was employed for the detection of fire-induced changes in a Mediterranean ecosystem. BFAST enables the decomposition of time series into trend, seasonal and noise components, resulting in the detection of gradual and rapid land cover changes. Normalised Difference Vegetation Index (NDVI) time series derived from the MODIS and VEGETATION (VGT) standard products were analysed. The time series decomposition resulted in the mapping of the burned area and the demonstration of the post-fire vegetation recovery trend. The observed gradual changes revealed an increase of NDVI values over time, indicating post-fire vegetation recovery. Spatial validation of the generated burned area maps with a higher resolution reference map was performed and probability statistics were derived. Both maps achieved a high probability of detection – 0.90 for MODIS and 0.87 for VGT – and a low probability of false alarms, 0.01 for MODIS and 0.02 for VGT. In addition, the Pareto boundary theory was implemented to account for the low-resolution bias of the maps. BFAST facilitated detection of fire-induced changes using image time series, without having to set thresholds, select specific seasons or adjust to certain land cover types. Further evaluation of the approach should focus on a more comprehensive assessment across regions and time.
Forest fuel management for wildfire prevention in Spain: a quantitative SWOT analysis
Authors: Marino Eva , Hernando Carmen , Planelles Rosa , Madrigal Javier , Guijarro Mercedes , Sebastián Ana
Published: March 2014

Spain is one of the Mediterranean countries most severely affected by wildfires during the last 30 years, despite enhanced fire suppression efforts. At present, forest area is increasing more in Spain than in any other European country, and also has one of the highest densities of fire ignitions. However, forest management plans have been developed for only 13% of Spanish forest areas. The objective of the present study was to assess the role of forest fuel management for wildfire prevention in Spain. Different fuel management techniques, including mechanical treatments, prescribed burning and controlled grazing, were considered. A quantitative SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis was performed, based on a thorough documentation review and on the opinions of forest fire experts. Results enabled the identification of obstacles that hinder the implementation of effective fuel management, and suggested strategic recommendations to overcome them. New opportunities related to rural development activities (e.g. promotion of ‘FIRESMART’ products) would be highly relevant in fire-prone forest areas. These opportunities should provide additional funding for sustainable forest management and could foster fuel management activities that would directly involve and benefit rural populations.
Everolimus in Patients with Severe Pulmonary Hypertension: A Safety and Efficacy Pilot Trial
Authors: Seyfarth Hans‐Jürgen , Hammerschmidt Stefan , Halank Michael , Neuhaus Petra , Wirtz Hubert R.
Published: March 2014

Despite the availability of vasodilating compounds, pulmonary hypertension (PH) of various origins remains a disease with a poor prognosis. In recent years, pulmonary arterial hypertension (PAH) has been recognized as a predominantly proliferative process. Everolimus, an inhibitor of the mammalian target of rapamycin (mTOR), inhibits cellular protein synthesis and growth not only in lymphocytes but also in cells of the vascular wall. Ten patients suffering from PAH (n = 8) or chronic thromboembolic PH (n = 2) with progressive disease despite therapy with at least 2 vasodilating drugs were included in a prospective open‐label pilot study. All patients were treated with everolimus in addition to their prior medication. Safety and tolerability were observed throughout the study. Pulmonary vascular resistance (PVR) and 6‐minute walk distance (6MWD) were considered coprimary end points. In 2 patients, study medication was stopped prematurely because of an adverse event. One patient had acute bronchitis, and the other had right heart decompensation. The remaining 8 patients exhibited a significant 31% decrease in PVR (median [interquartile range], 1,012 [688–1,344] vs. 663 [546–860] dyn s cm−5; P = 0.018) and an increase in 6MWD (median [interquartile range], 236 [139–350] vs. 298 [207–450] m; P = 0.069) after 6 months of treatment with everolimus. In conclusion, in this pilot study antiproliferative therapy with everolimus was well tolerated in patients with PH. The observed improvements in PVR and 6MWD may stimulate further consideration of mTOR inhibition with everolimus for the treatment of PH.
Acute Effects of Sildenafil and Dobutamine in the Hypertrophic and Failing Right Heart in Vivo
Authors: Andersen Asger , Nielsen Jan M. , Rasalingam Sivagowry , Sloth Erik , Nielsen‐Kudsk Jens Erik
Published: March 2014

The purpose of this study was to investigate whether acute intravenous administration of the phosphodiesterase type 5 (PDE‐5) inhibitor sildenafil in a single clinically relevant dose improves the in vivo function of the hypertrophic and failing right ventricle (RV). Wistar rats (n = 24) were subjected to pulmonary trunk banding (PTB) causing RV hypertrophy and failure. Four weeks after surgery, they were randomized to receive an intravenous bolus dose of sildenafil (1 mg/kg; n = 7), vehicle (n = 6), or dobutamine (10 μg/kg; n = 6). Invasive RV pressures were recorded continuously, and transthoracic echocardiography was performed 1, 5, 15, 25, 35, 50, 70, and 90 minutes after injecting the bolus. Cardiac function was compared to baseline measurements to evaluate the in vivo effects of each specific treatment. The PTB procedure caused significant hypertrophy, cardiac fibrosis, and reduction in RV function evaluated by echocardiography (TAPSE) and invasive pressure measurements. Sildenafil did not improve the function of the hypertrophic failing right heart in vivo, measured by TAPSE, RV systolic pressure (RVsP), and dp/dtmax. Dobutamine improved RV function 1 minute after injection measured by TAPSE (0.1242 ± 0.03 vs. 0.1565 ± 0.04 cm; P < 0.001), RVsP (83 ± 11 vs. 107 ± 11 mmHg; P < 0.001), and dp/dtmax (3, 136 ± 521 vs. 4, 489 ± 706 mmHg/s; P < 0.001). Acute administration of the PDE‐5 inhibitor sildenafil in a single clinically relevant dose did not modulate the in vivo function of the hypertrophic failing right heart of the rat measured by echocardiography and invasive hemodynamics. In the same model, dobutamine acutely improved RV function.
Anatomical Considerations for the Development of a New Transcatheter Aortopulmonary Shunt Device in Patients with Severe Pulmonary Arterial Hypertension
Authors: Guo Kenneth , Langleben David , Afilalo Jonathan , Shimony Avi , Leask Richard , Marelli Ariane , Martucci Giuseppe , Therrien Judith
Published: March 2014

Morbidity from pulmonary arterial hypertension (PAH) ensues when the pulmonary pressure reaches suprasystemic levels. A transcatheter alternative to the Potts shunt would allow decompression of the right heart without the surgical risks. To aid development of a transcatheter aortopulmonary shunt (TAPS) device, we described the anatomic relationship between the left pulmonary artery (LPA) and the descending aorta (dAO) in adults with severe pulmonary hypertension. Adults with severe PAH (peak systolic pulmonary arterial pressure [PASP] ≥80 mmHg) who had computed tomography of the chest were enrolled. Measurements were taken on the axial plane at the level of the pulmonary artery bifurcation. Forty patients (male sex, 9 patients; median age ± standard deviation [SD], 59 ± 15 years; median PASP ± SD, 93 ± 12 mmHg) were identified. The mean distance (±SD) between the LPA and dAO was 2.3 ± 3.1 mm. The mean luminal dAO and LPA diameters (±SD) were 23.4 ± 3.8 mm and 25.5 ± 5.1 mm, respectively. The LPA and dAO approximated in 93% of patients, with 38% having aortic calcification at the contact site. The mean “landing zone” width and height (defining an area with distance <4 mm between the outer borders) of the two arteries were 15.7 ± 3.4 mm and 20.6 ± 4.3 mm, respectively, at a mean distance of 28.0 ± 7.6 mm from the main pulmonary artery bifurcation. This study shows that the landing zone is able to accommodate a TAPS device of up to 15 mm in diameter in the majority of patients with severe PAH.
Pulmonary 2‐Deoxy‐2‐[18F]‐Fluoro‐D‐Glucose Uptake is Low in Treated Patients with Idiopathic Pulmonary Arterial Hypertension
Authors: Ruiter Gerrina , Wong Yeun Ying , Raijmakers Pieter , Huisman Marc C. , Lammertsma Adriaan A. , Knaapen Paul , de Man Frances S. , Westerhof Nico , van der Laarse Willem J. , Vonk‐Noordegraaf Anton
Published: March 2014

Glucose metabolism measurement using 2‐deoxy‐2‐[18F]‐fluoro‐D‐glucose (18FDG) positron emission tomography (PET) could provide in vivo information about pulmonary vascular remodeling. The purpose of this study was to assess whether pulmonary 18FDG uptake in idiopathic pulmonary arterial hypertension (IPAH) patients changes and, if so, to determine whether the change is related to disease severity and survival. Sixteen IPAH patients who were treated with IPAH‐specific therapy and 7 patients who had a myocardial infarction (MI) without pulmonary hypertension were included. IPAH disease severity was determined using the 6‐minute walk test and right heart catheterization 2 days before 18FDG PET. Regions of interest were defined for left and right lungs, and standardized uptake values (SUVs), normalized to body weight, injected dose, and plasma glucose level, were derived. Mean SUVs for IPAH left and right lungs were 0.40 ± 0.26 and 0.44 ± 0.18 (P = 0.32), respectively. In MI patients, SUVs were 0.38 ± 0.13 and 0.35 ± 0.10 (P = 0.24) in left and right lungs, respectively. Total lung SUVs were similar in IPAH and MI patients (0.41 ± 0.19 vs. 0.37 ± 0.11; P = 0.56). There was no correlation between SUV and IPAH disease severity parameters. In addition, lung SUV did not predict survival in IPAH patients (hazard ratio, 1.155; 95% confidence interval, 0.16–8.26; P = 0.88). In conclusion, pulmonary 18FDG uptake in treated IPAH patients is low and is not associated with disease severity and survival, thereby limiting its clinical use in patient care.
Conformal fractals for normal subgroups of free groups
Authors: Jaerisch Johannes
Published: March 2014

We investigate subsets of a multifractal decomposition of the limit set of a conformal graph directed Markov system which is constructed from the Cayley graph of the free groupFdF_{d}with at least two generators. The subsets we consider are parametrised by a normal subgroupNNofFdF_{d}and mimic the radial limit set of a Kleinian group. Our main results show that, regarding the Hausdorff dimension of these sets, various results for Kleinian groups can be generalised. Namely, under certain natural symmetry assumptions on the multifractal decomposition, we prove that, for a subset parametrised byNN, the Hausdorff dimension is maximal if and only ifFd/NF_{d}/Nis amenable and that the dimension is greater than half of the maximal value. We also give a criterion for amenability via the divergence of the Poincaré series ofNN. Our results are applied to the Lyapunov spectrum for normal subgroups of Kleinian groups of Schottky type.
Induction of T-cell memory by a dendritic cell vaccine: a computational model
Authors: Pappalardo Francesco , Pennisi Marzio , Ricupito Alessia , Topputo Francesco , Bellone Matteo
Published: March 2014

Motivation: Although results from phase III clinical trials substantially support the use of prophylactic and therapeutic vaccines against cancer, what has yet to be defined is how many and how frequent boosts are needed to sustain a long-lasting and protecting memory T-cell response against tumor antigens. Common experience is that such preclinical tests require the sacrifice of a relatively large number of animals, and are particularly time- and money-consuming.

Results: As a first step to overcome these hurdles, we have developed an ordinary differential equation model that includes all relevant entities (such as activated cytotoxic T lymphocytes and memory T cells), and investigated the induction of immunological memory in the context of wild-type mice injected with a dendritic cell-based vaccine. We have simulated the biological behavior both in the presence and in the absence of memory T cells. Comparing results of ex vivo and in silico experiments, we show that the model is able to envisage the expansion and persistence of antigen-specific memory T cells. The model might be applicable to more complex vaccination schedules and substantially in any biological condition of prime-boosting.

Availability and implementation: The model is fully described in the article.

Contact:  fp@francescopappalardo.net

Supplementary information:  Supplementary data are available at Bioinformatics online.
PyRAD: assembly of
de novo
RADseq loci for phylogenetic analyses
Authors: Eaton Deren A. R.
Published: March 2014

Motivation:  Restriction-site–associated genomic markers are a powerful tool for investigating evolutionary questions at the population level, but are limited in their utility at deeper phylogenetic scales where fewer orthologous loci are typically recovered across disparate taxa. While this limitation stems in part from mutations to restriction recognition sites that disrupt data generation, an additional source of data loss comes from the failure to identify homology during bioinformatic analyses. Clustering methods that allow for lower similarity thresholds and the inclusion of indel variation will perform better at assembling RADseq loci at the phylogenetic scale.

Results:   PyRAD is a pipeline to assemble de novo RADseq loci with the aim of optimizing coverage across phylogenetic datasets. It uses a wrapper around an alignment-clustering algorithm, which allows for indel variation within and between samples, as well as for incomplete overlap among reads (e.g. paired-end). Here I compare PyRAD with the program Stacks in their performance analyzing a simulated RADseq dataset that includes indel variation. Indels disrupt clustering of homologous loci in Stacks but not in PyRAD , such that the latter recovers more shared loci across disparate taxa. I show through reanalysis of an empirical RADseq dataset that indels are a common feature of such data, even at shallow phylogenetic scales. PyRAD uses parallel processing as well as an optional hierarchical clustering method, which allows it to rapidly assemble phylogenetic datasets with hundreds of sampled individuals.

Availability :   Software is written in Python and freely available at http://www.dereneaton.com/software/

Contact:   daeaton.chicago@gmail.com

Supplementary Information:   Supplementary data are available at Bioinformatics online.
Frag’r’Us: knowledge-based sampling of protein backbone conformations for
de novo
structure-based protein design
Authors: Bonet Jaume , Segura Joan , Planas-Iglesias Joan , Oliva Baldomero , Fernandez-Fuentes Narcis
Published: March 2014

Motivation The remodeling of short fragment(s) of the protein backbone to accommodate new function(s), fine-tune binding specificities or change/create novel protein interactions is a common task in structure-based computational design. Alternative backbone conformations can be generated de novo or by redeploying existing fragments extracted from protein structures i.e. knowledge-based. We present Frag’r’Us, a web server designed to sample alternative protein backbone conformations in loop regions. The method relies on a database of super secondary structural motifs called s motifs. Thus, sampling of conformations reflects structurally feasible fragments compiled from existing protein structures.

Availability and implementation Frag’r’Us has been implemented as web application and is available at http://www.bioinsilico.org/FRAGRUS .

Contact  narcis.fernandez@gmail.com or baldo.oliva@upf.edu

Supplementary information  Supplementary data are available at Bioinformatics online.
The future of fisheries oceanography lies in the pursuit of multiple hypotheses
Authors: Hare Jonathan A.
Published: March 2014

Fisheries oceanography is largely an applied discipline with a major goal of improving fisheries management and marine conservation. Johan Hjort's critical period hypothesis, and its decedents, remain a dominant theme and focuses on year-class success as mediated by prey availability and feeding. Bottom-up forcing, a related hypothesis, focuses on the sequential transfer of energy through the pelagic foodweb from primary productivity to fishery productivity. Another approach assumes that trophic interactions of adults determine abundance. Fisheries assessment and management, however, is based on the hypothesis that fishery abundance is determined by time-varying fishing and year-class success related to spawning-stock biomass. These approaches, their basic hypotheses, and underlying processes and mechanisms suggest very different dynamics for fishery populations. Other hypotheses challenge these traditional views: predation of early life stages, parental condition, shifting migration pathways, and physiological limits. Support for these other hypotheses is reviewed and the research needs are described to apply these hypotheses to fisheries assessment and management. Some of these hypotheses were identified by Hjort (e.g. parental condition hypothesis) and others are relative new (e.g. early life stage predation hypothesis). Moving into the future, we should focus on Hjort's approach: multi-hypothesis, integrative, and interdisciplinary. A range of hypotheses should be pursued with an emphasis on comparing and linking multiple hypotheses. The results then must be incorporated into fishery assessments and management decisions to support the long-term sustainability of exploited species and the conservation of threatened and endangered species.
Why the complex nature of integrated ecosystem assessments requires a flexible and adaptive approach
Authors: Dickey-Collas Mark
Published: March 2014

This article considers the approach taken by the ICES to integrated ecosystem assessments (IEAs) in the context of the wider evolution of IEAs and the science/policy landscape within the ICES region. It looks forward and considers the challenges facing the development of IEAs, specifically those of scoping for objectives, participatory engagement, developing indicators and targets, risk analysis, and creating tools to evaluate management measures for marine anthropogenic activities. It concludes that expectations that the implementation of IEAs will take an ordered, stepwise approach will lead to disappointment and frustration. This is a consequence of the need to operate in an adaptive manner in a complex system. The ecosystem, the science support infrastructure, and the governance systems are all complex. Plus when engaged in a debate about societal objectives, we expect to encounter a complex and changing landscape. As a community, the challenge is to find leverage mechanisms to encourage IEA efforts to provide insights and tools within resources. We will need to innovate and be responsive to the complexity of the ecosystem and governance structures encountered when performing IEA.
Long-Term Conservation of Adiabatic Invariants by Using Symplectic Integrators
Authors: Shimada Masaaki , Yoshida Haruo
Published: March 2014

The advantage of symplectic integrators compared with non-symplectic Runge-Kutta integrators is shown in the computation of adiabatic invariants. Symplectic integrators do not produce a secular growth of the error, contrary to non-symplectic Runge-Kutta integrators. Furthermore, we compared the performance of 2nd, 4th, and 6th order symplectic integrators and obtained the numerical results that show SI6 has the best performance when the numerical error in the adiabatic invariants must be below 0.03%. The model systems that we used are a one-dimensional harmonic oscillator with a slowly varying frequency and a one-particle system in a slowly varying isochrone potential.
CO Observations of a Galaxy behind the Galactic Plane, Dwingeloo 1
Authors: Kuno Nario , Vila-Vilaró Baltasar , Nishiyama Kohta
Published: March 2014

We have observed Dwingeloo 1, which was discovered behind the disk of the Milky Way in 1994, in the CO (J = 1−0) line transition with the Nobeyama 45-m telescope. We detected very weak CO line emission in the optical bar and marginally at the center. The surface density of molecular gas derived using the Galactic conversion factor N(H2)/ICO = 2.6 × 1020 in only 8.4 M⊙ pc-2, correcting for the inclination of the galaxy even in the center. The central surface density of molecular gas and the M(H2)/M(H I) ratio indicate that Dwingeloo 1 is a molecular gas-poor galaxy.
Nonlinear Pulsation Driven by Strange Modes in Hydrodynamic Models
Authors: Aikawa Toshiki , Sreenivasan S. Ranga
Published: March 2014

The characteristics of the nonlinear pulsation of hydrodynamic models, which have only strange modes as pulsational unstable modes, are compared with those by conventional modes. It is shown that nonlinear pulsation with the strange modes has considerable amplitudes only at the hydrogen ionization zone and in the atmosphere. This is sharp in contrast to that by conventional modes, and is identical with the characteristics of the unstable linear strange modes. We thus conclude that the unstable strange modes may be responsible for the nonlinear pulsation. We also discuss the physical origin of the instability of the strange modes. Since the modes are pulsationally unstable without any luminosity perturbation, other physical mechanisms must be involved for the instability along with the conventional kappa and gamma mechanisms, which are familiar in Cepheid variables. We suggest that the density inversion in the H ionization region, including the adjacent He I ionization zone, may be the origin. Finally, we suggest that the different pulsation driving zones may cause the feature of the spatial amplitude variations.
Global 3- and 7-mm VLBI Observations of OJ 287
Authors: Tateyama Claudio E. , Inoue Makoto , Krichbaum Thomas P. , Bååth Lars B. , Kameno Seiji , Rogers Alan E. E. , Alberdi Antonio , Backer Don C. , Bartel Norbert , Booth Roy S. , Burke Bernard F. , Carlstrom John E. , Dhawan Vivek , Dickman Robert L. , Emerson Darrel T. , Hirabayashi Hisashi , Hodges Mark W. , Graham David A. , Johnston Kenneth J. , Kobayashi Hideyuki , Kus Andrzej J. , Padin Stephen , Plambeck Richard L. , Predmore C. Read , Quirrenbach Andreas , Lawrence Charles R. , Lamb James , Marcaide Juan M. , Morimoto Masak , Ronnang Bernt O. , Shapiro Irwin I. , Spencer John H. , Witzel Arno , Woody David , Wright Melvyn C. H.
Published: March 2014

We present new results from global VLBI observations of the highly active blazar OJ 287 at 7 and 3 mm wavelengths. We show the first map of the mas to sub-mas structure of OJ 287 at 43 GHz and discuss this image in the context with models of the source structure seen at 100 GHz.
Large-Amplitude Superhumps in ER Ursae Majoris during the Earliest Stage of a Superoutburst
Authors: Kato Taichi , Nogami Daisaku , Masuda Seiji
Published: March 2014

Time-resolved CCD photometry of a peculiar SU UMa-type dwarf nova, ER UMa, during the earliest stage of superoutbursts revealed the existence of large-amplitude (˜ 0.35 mag) superhumps. These superhumps appear at, or even during, the rise to the superoutburst maximum, and show a rapid decay of amplitudes with a time scale of a few days. After a period showing a low-amplitude variation, superhumps with more usual singly-peaked profiles appear in the later stage of the superoutburst. Such an early appearance of superhumps seems to contradict the current growth model of superhumps or tidal instability, whose growth rate has been shown to be proportional to the square of the binary mass ratio. Several possibilities to explain this anomaly are also briefly discussed, as well as a comparison with other early stage superhumps in WZ Sge stars.
The Gas Imaging Spectrometer on Board ASCA
Authors: Ohashi Takaya , Ebisawa Ken , Fukazawa Yasushi , Hiyoshi Kenji , Horii Michihiro , Ikebe Yasushi , Ikeda Hitoshi , Inoue Hajime , Ishida Manabu , Ishisaki Yoshitaka , Ishizuka Toshio , Kamijo Shunsuke , Kaneda Hidehiro , Kohmura Yoshiki , Makishima Kazuo , Mihara Tatehiro , Tashiro Makoto , Murakami Toshio , Shoumura Riichirou , Tanaka Yasuo , Ueda Yoshihiro , Taguchi Koji , Tsuru Takeshi , Takeshima Toshiaki
Published: March 2014

The Gas Imaging Spectrometer (GIS) system on board ASCA is described. The experiment consists of 2 units of imaging gas scintillation proportional counters with a sealed-off gas cell equipped with an imaging phototube. The performance is characterized by the high X-ray sensitivity (from 0.7 keV to over 10 keV), good energy resolution (7.8% FWHM at 6 keV following E−0.5 as a function of X-ray energy E), moderate position resolution (0.5 mm FWHM at 6 keV with E−0.5 dependence), fast time resolution down to 61 μs, and an effective area of 50 mm diameter. The on-board signal processing system and the data transmitted to the ground are also described. The background rejection efficiency of the GIS is reaching the level achieved by the non-imaging multi-cell proportional counters.
The X-Ray Structure of A399 and A401: A Pre-Merging Cluster Pair
Authors: Fujita Yutaka , Koyama Katsuji , Tsuru Takeshi , Matsumoto Hironori
Published: March 2014

We present ASCA results of the pair clusters A399 and A401. The region between the two clusters exhibits excess X-rays over the value expected with a simple superposition of the two clusters. We have found, however, no temperature rise at the merging front; the temperature is near the average of those in the inner regions of the two clusters. These facts indicate that although the two clusters are really interacting, it is not presently strong. The inner regions of the two clusters show no radial variations in the temperature, abundance or absorption. We set upper-limits of the mass-deposition rate of cooling flow to be Ṁ < 35 M⊙yr−1 and Ṁ < 59 M⊙yr−1 for A399 and A401, respectively. A hint of an azimuthal variation in the temperature was also found.
The Variable O VIII Warm Absorber in MCG–6–30–15
Authors: Otani Chiko , Kii Tsuneo , Reynolds Christopher S. , Fabian Andrew C. , Iwasawa Kazushi , Hayashida Kiyoshi , Inoue Hajime , Kunieda Hideyo , Makino Fumiyoshi , Matsuoka Masaru , Tanaka Yasuo
Published: March 2014

We present the results of a 4-day ASCA observation of the Seyfert galaxy MCG–6–30–15, focusing on the nature of X-ray absorption by the warm absorber, characterized by the K-edges of highly ionized oxygen, O VII and O VIII. We have confirmed that the column density of O VIII changes on a timescale of ∼ 104 s when the X-ray continuum flux decreases. A significant anti-correlation of the column density with the continuum flux gives direct evidence that the warm absorber is photoionized by the X-ray continuum. From the timescale of the variation of the O VIII column density, we have estimated that it originates from gas within a radius of about 1017 cm of the central engine. In contrast, the depth of the O VII edge shows no response to the continuum flux, which indicates that it originates in gas at larger radii. Our results strongly suggest that there are two warm absorbing regions: one is located near or within the Broad Line Region; the other is associated with the outer molecular torus, scattering medium or Narrow Line Region.
On the Chemical Evolution of Our Galaxy
Authors: Mihara Kuniko , Takahara Fumio
Published: March 2014

We have investigated the chemical evolution of the solar neighborhood with a particular emphasis on the helium abundance and the current supernova (SN) rate, while taking into account the effects of the stellar mass loss on nucleosynthesis in stars. We found that the Scalo IMF can reproduce the solar-helium abundance as well as the current ratio of type-Ia to type-(Ib+II) SNe for a suitable choice of the closebinary fraction. A current type-Ia to type-(Ib+II) SNe ratio as low as 0.1 is favored in order to reproduce the solar-iron abundance. We have noticed that there exists a method to estimate the mass-to-luminosity ratio of our Galaxy and the Hubble constant by assuming that the current SNe rate of our Galaxy is the same as that of external Sbc galaxies. By combining our best model prediction, M / LB = 12.3 h2 , with the observed value, M/LB = 7.6 h, we obtained M/LB = 4.7 and H0 ∼ 62 [km s−1Mpc−1] with a fairly large uncertainty.
Microlensing and Halo Models of the Galaxy
Authors: Kan-ya Yukitoshi , Nishi Ryoichi , Nakamura Takashi
Published: March 2014

We investigated the dependence of the optical depth (τ) of microlensing events on certain model parameters of the galactic halo. We only considered models in which the rotation curve inside the sun is compatible with the observation. It was found that τ varies up to a factor of 3.5 from those spherical models with a flat rotation curve. This implies that only the most centrally concentrated halo model can be consistent with observation if the halo consists of only MACHOs. We also discuss the power (x) of IMF of MACHOs consistent with the observation by Tyson (1988, AAA 46.157.001) and Bahcall et al. (1994, AAA 62.155.120) assuming that MACHOs are low-mass stars. It is found that x is greater than 5.
13CO (J= 1–0) Observations of the Lupus Molecular Clouds
Authors: Tachihara Kengo , Dobashi Kazuhito , Mizuno Akira , Ogawa Hideo , Fukui Yasuo
Published: March 2014

Large-scale 13CO (J = 1–0) observations were carried out toward the Lupus region using the new 4-m millimeter-wave telescope at Nagoya University (HPBW = 2′.7). Four molecular clouds (Lupus 1, 2, and 3 and a newly found cloud) were mapped using an 8′ grid spacing. The masses of the four clouds were estimated to be 1200, 100, 300, and 1000 M⊙, respectively. Around an infrared point source, IRAS 15398–3359, associated with Lupus 1, we discovered a CO molecular outflow with a relatively short dynamical time scale of ∼ 2000 yr, which indicates ongoing star formation in the Lupus region. Including the outflow source, about 50 candidates for young stellar objects can be found in the literature, which are apparently associated with 13CO clouds. Comparing these objects with our 13CO data, we find that the star-formation efficiency of the four clouds varies over a wide range from 0.4 to ≥ 3.8%, which might represent their different stages of star formation, or might be due to a difference in the interaction with the nearby Scorpius HI shell.
ASCA Observation of the Rapid Burster in Quiescence
Authors: Asai Kazumi , Dotani Tadayasu , Kunieda Hideyo , Kawai Nobuyuki
Published: March 2014

We observed the Rapid Burster in quiescence and detected a significant X-ray flux for the first time. Neither a type-I nor type-II burst was observed during the observation. The luminosity was estimated to be (3+2−1) × 1033 erg s−1 (2–10 keV), assuming a power-law with a photon index of 2 and a distance of 10 kpc. This luminosity is comparable to that of neutron-star transients in quiescence. If mass accretion is responsible for the X-ray emission, we can constrain the magnetic-field strength and spin period of the neutron star. A highly magnetized, rapidly rotating neutron star may be excluded.
Iron-Line Diagnostics of the Jets of SS 433
Authors: Kotani Taro , Kawai Nobuyuki , Matsuoka Masaru , Brinkmann Wolfgang
Published: March 2014

The X-ray spectra of SS 433 were measured with ASCA at a precession phase 0.48 when the Doppler-shifted iron lines from both the receding and approaching jets were clearly separated. The X-ray emission lines of SS 433 were analyzed on the basis of a numerical model of the radiatively cooling jets. The measured intensities of the iron-emission lines were compared with the results from numerical calculations in order to constrain the physical parameters of the jets, such as the temperature, mass outflow rate, density, and length. We also studied the emission lines from elements with smaller atomic number, and found that these lines were heavily absorbed only in the receding jet. This implies the existence of absorbing gas in a precessing plane perpendicular to the jets.
Doppler Tomography of Relativistic Accretion Disks
Authors: Karas Vladimír , Kraus Pavel
Published: March 2014

Spectral lines from a source orbiting around a compact object are studied. Time variations of observed frequency and count rate due to motion of the source and gravitational lensing are considered. Gravitational field of the central object is described by the Kerr metric. It is shown that: (i) simultaneous temporal and frequency resolution enables us to restrict parameters of the model (inclination angle, position of the source, angular momentum of the black hole); (ii) techniques of image restoration, familiar from other fields of astronomy, can be applied to study inner regions of active galactic nuclei. This contribution is relevant for extremely variable X-ray sources with high parameter of efficiency, such as Seyfert 1 galaxy PHL 1092 observed by ROSAT.
Ion Tail Disturbance of Comet C/Hyakutake 1996B2 Observed around the Closest Approach to the Earth
Authors: Kinoshita Daisuke , Fukushima Hideo , Watanabe Jun-ichi , Yamamoto Naotaka
Published: March 2014

A sequential imaging observation of the ion tail of Comet C/Hyakutake 1996B2 was carried out on 1996 March 25 with a wide-field CCD imaging camera developed at the National Astronomical Observatory of Japan. We detected a peculiar knot receding along the main axis of the ion tail during our observation. This knot was located at 5.0 × 106 km from the nucleus on March 25.6 UT, and moved about 2.0 × 106 km during 5 hr. The measured velocity along the axis of the ion tail was derived to be 99.2 ± 0.3 km s−1 , which is almost constant within the observational limit. We also measured the perpendicular motion of this knot to the axis, and identified rapid acceleration. The brightness of the knot decreased during the observation. We report on preliminary results of an analysis of this phenomenon, and discuss some characteristics in this paper.
Discovery of Hard X-Rays from a Cluster of Protostars
Authors: Koyama Katsuji , Hamaguchi Kenji , Ueno Shiro , Kobayashi Naoto , Feigelson Eric D.
Published: March 2014

We report on the detection of hard X-rays from protostar candidates (Class I sources) in the R Coronae Australis (R CrA) molecular cloud. The hard X-rays are found even in the quiescent states with extremely high temperature of about 6 keV. One of the sources, probably the embedded far-infrared source R1, exhibited a powerful X-ray flare. These phenomena are similar to, but with a significantly higher temperature than, those seen in T Tauri stars. The flare spectrum is unusual, showing a broadened or double emission-line structure between 6.2 and 6.8 keV. Since X-rays are unexpected from current protostellar theory, these ASCA observations should have a significant impact on our understanding of star formation and the earliest phases of stellar evolution.
Accretion in Gravitationally Contracting Clouds
Authors: Tomisaka Kohji
Published: March 2014

Accretion flow in a contracting magnetized isothermal cloud was studied using magnetohydrodynamical simulations and a nested grid technique. First, the interstellar magnetized cloud experiences a “runaway collapse” phase, in which the central density increases drastically within a finite time scale. Finally, it enters an accretion phase, in which inflowing matter accretes onto a central high-density disk or a new-born star. We found that the accretion rate reaches (4–40) × cs3/G , where cs and G represent the isothermal sound speed and the gravitational constant, respectively. This is much larger than the standard accretion rate of 0.975cs3/G for a hydrostatic isothermal spherical cloud (Shu 1977, AAA 19.065.044). Due to the effect of an extra infall velocity achieved in the runaway phase (∼ 2cs), the accretion rate is boosted. This rate declines with time in contrast to Shu's solution, but keeps ≳ 2.5cs3/G. The observed gas infall rate around proto-stars such as L1551 IRS 5 and HL Tau is also discussed.
Interaction of Jets with a Supernova Remnant in the SS 433/W50 System
Authors: Murata Kenji , Shibazaki Noriaki
Published: March 2014

The well known for the precessing relativistic jet SS 433 is located near to the center of the radio source W50. The radio shell of W50 is elongated in the direction of the jets to give ear-like structures. X-ray lobes are found between the radio ears and SS 433. We consider the interaction of the jets with the supernova remnant shell for the radio ears and X-ray lobes. We show that the expansion of the shell is enhanced at the part which in being pushed by the jets to yield the ear-like structures, and that the electrons accelerated at the reverse shocks emit synchrotron X-rays, as observed from the lobes. Comparing with the observations, we set constraints on the physical properties of the jets and interstellar matter.
A Near-Infrared Imaging Search for Invisible Galaxies behind the Milky Way
Authors: Iwata Ikuru , Nakanishi Kouichiro , Takeuchi Tsutomu , Saitō Mamoru , Yamashita Takuya , Nishihara Eiji , Okumura Shin-ichiro
Published: March 2014

We carried out a near-infrared imaging search for optically obscured galaxies behind the Milky Way. The imagings were made for a 4′ × 4′ field on each of 58 IRAS point sources, located within a region of 90° < l < 240°, |b| < 10° and having reliable flux densities at 25, 60, and 100 μm, but no Galactic CO emission. The results revealed that 16 of these IRAS point sources can be associated with galaxies or possible galaxies, and another 16 can be associated with stars or HII regions; however, the remaining 26 are ‘empty’ objects without any optical and near-infrared counterpart. The empty objects are colder than galaxies and seem to be Galactic objects.
A Steady Hydrodynamical Turbulence in Differentially Rotating Disks
Authors: Kato Shoji , Yoshizawa Akira
Published: March 2014

The purpose of this paper is to suggest a possible presence of steady hydrodynamical (non-MHD) turbulence in differentially rotating disks. This turbulence is assumed to be described by a second-order closure modeling. It is further assumed that the turbulence is incompressible and locally homogeneous in the horizontal direction, except that a strong differential rotation is present. The results suggest that steady turbulent states might be possible by isotropizing effects of a pressure-strain tensor. The limitations of our approach are discussed briefly.
Distribution and Dynamics of Molecular Gas in the Galaxy M51. III. Kinematics of Molecular Gas
Authors: Kuno Nario , Nakai Naomasa
Published: March 2014

We present here a study of the dynamics of the molecular gas in the spiral galaxy M51 using CO data obtained with the Nobeyama 45-m telescope. From the distribution of the radial velocity of the CO gas, the velocity components parallel and perpendicular to the spiral arms were determined for each spiral phase. Although the variations in the velocity components across the arms are in qualitatively good agreement with density-wave theory, their magnitudes are much larger than those predicted by models with small-amplitude perturbations (5–10% of axisymmetric field). By tracing the velocity vectors at each spiral phase, the orbit of the CO gas was observationally determined. The orbits deviate largely from pure circular motions, forming an oval pattern, as expected from density-wave theory. The arm-to-interarm ratio of the surface density of the gas can be explained in terms of this oval motion. In addition, both the smooth deceleration across the arms and the symmetric density distribution with respect to the arms suggest the lack of the galactic shock expected in a continuous fluid model.
Inner Edge Drag by the Compact Star and Disc Structure and Dynamics in Close Binary Systems: 3D SPH Numerical Experiments
Authors: Belvedere Gaetano , Lanzafame Giuseppe
Published: March 2014

The aim of this work is to study the effect of the drag exerted by an asynchronous primary on accretion disc structure and dynamics in an interacting close binary system. Comparison of two 3D SPH disc simulations has been performed, the first relative to the customary synchronous case, the second to an asynchronous one, assuming the primary rotational axis to be perpendicular to the orbital plane, and, in the latter case, the rotational angular velocity to be twice the orbital one, namely ω = 2 ωo. Some tests have been carried out also in the cases: ω = 1.5 ωo, ω = 5 ωo and ω = 10 ωo, where ω is the primary angular velocity and ωo is the orbital angular velocity. The results relative to the ω = 2 ωo model show a hot accretion disc whose inner edge is characterized by an asymmetric rotational motion, an azimuthal compression wave and a rotating local bump, which may explain luminosity variations observed in close binary systems. A hot wind coming from the outer edge of the disc is also found. In this asynchronous model the accretion and ejection mass rates are lower and higher respectively, in comparison to those characteristic of the synchronous model. For faster rotation rates ω, the tests performed indicate that high ejection mass rates, both from the outer and inner edges, do not allow the development of a well defined accretion disc.
New SU UMa-Type Dwarf Nova CC CANCRI
Authors: Kato Taichi , Nogami Daisaku
Published: March 2014

The dwarf nova CC Cnc was observed during three bright outbursts in 1993, 1995, and 1996. V-band time-resolved CCD photometry revealed superhumps with a period of 0.0771 d or its alias 0.0835 d, and an amplitude of 0.23 mag. The yielded periods are likely to preclude a previous claim of CC Cnc as being a dwarf nova in the period gap.
Linear and Nonlinear Evolution of the Parker Instability of Magnetic-Flux Sheets in Co-Rotating Coordinates
Authors: Chou Wenchien , Tajima Toshiki , Matsumoto Ryoji , Shibata Kazunari
Published: March 2014

We present a study of the magnetic buoyancy instability (or Parker instability) of stellar atmospheres, in particular that of the effect of the Coriolis force, via a linear stability analysis and nonlinear 3-D MHD simulations. We find that fast rotation stabilizes this mode for a toroidal flux sheet located near to the equator: magnetic flux sheets in low-latitude regions are locally stable, while the growth rate of the flux sheet near to the polar zone is not much reduced by the Coriolis effect. This may explain the observational result that stellar spots of fast rotating stars appear toward the polar region. Another effect of the Coriolis force is that there is a cut-off rotational angular velocity above which the long-wavelength transverse perturbations are more unstable than the short wavelength ones. This may explain why large stellar patches are observed in fast rotating stars. 3-D simulations of magnetic flux sheets under buoyancy instability have also been carried out in co-rotating Cartesian coordinates. The simulation results show that the combination of the buoyancy instability and the Coriolis effect gives rise to a mechanism to twist the magnetic-flux sheet embedded in the solar (or stellar) atmosphere of a slowly rotating star (such as the Sun), emerging to the surface with a helical structure. We suggest that this can be a model to explain the S-shaped active regions in the low latitudes of the Sun shown in the soft X-ray picture taken by the Yohkoh satellite.
Discovery of Non-Thermal X-Rays from the Northwest Shell of the New SNR RX J1713.7–3946: The Second SN 1006?
Authors: Koyama Katsuji , Kinugasa Kenzo , Matsuzaki Keiichi , Nishiuchi Mamiko , Sugizaki Mutsumi , Torii Ken'ichi , Yamauchi Shigeo , Aschenbach Bernd
Published: March 2014

We report on the ASCA results of a featureless X-ray spectrum from RX J1713.7–3946, a new shell-like SNR discovered with the ROSAT all-sky survey. The northwest part of RX J1713.7–3946 was in the field of the ASCA Galactic Plane Survey Project, and was found to exhibit a shell-like structure. The spectrum, however, shows neither line emission nor any signature of a thermal origin. Instead, a power-law model with a photon index of 2.4–2.5 gives a reasonable fit to the spectrum, suggesting a non-thermal origin. Together with the similarity to SN 1006, we propose that RX J1713.7–3946 is the second example, after SN 1006, of synchrotron X-ray radiation from a shell of SNRs. Since the synchrotron X-rays suggest the existence of extremely high energy charged particles in the SNR shell, our discovery should have a strong impact on the origin of cosmic X-rays.