On the shape of the mass-function of dense clumps in the Hi-GAL fields. II. Using Bayesian inference to study the clump mass function

Context. Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin, their evolution and their detailed physical properties. In particular, the relationship between the mass distribution of these clumps (also known as the "clump mass function", or CMF) and the stellar initial mass function (IMF), is still poorly understood. Aims. In order to better understand how the CMF evolve toward the IMF, and to discern the "true" shape of the CMF, large samples of bona-fide pre- and proto-stellar clumps are required. Two such datasets obtained from the Herschel infrared GALactic Plane Survey (Hi-GAL) have been described in paper I. Robust statistical methods are needed in order to infer the parameters describing the models used to fit the CMF, and to compare the competing models themselves. Methods. In this paper we apply Bayesian inference to the analysis of the CMF of the two regions discussed in Paper I. First, we determine the Bayesian posterior probability distribution for each of the fitted parameters. Then, we carry out a quantitative comparison of the models used to fit the CMF. Results. We have compared the results from several methods implementing Bayesian inference, and we have also analyzed the impact of the choice of priors and the influence of various constraints on the statistical conclusions for the preferred values of the parameters. We find that both parameter estimation and model comparison depend on the choice of parameter priors. Conclusions. Our results confirm our earlier conclusion that the CMFs of the two Hi-GAL regions studied here have very similar shapes but different mass scales. Furthermore, the lognormal model appears to better describe the CMF measured in the two Hi-GAL regions studied here. However, this preliminary conclusion is dependent on the choice of parameters priors.Comment: Submitted for publication to A&A on November 12, 2013. This paper contains 11 pages and 7 figure

Ground state numerical study of the three-dimensional random field Ising model

The random field Ising model in three dimensions with Gaussian random fields is studied at zero temperature for system sizes up to 60^3. For each realization of the normalized random fields, the strength of the random field, Delta and a uniform external, H is adjusted to find the finite-size critical point. The finite-size critical point is identified as the point in the H-Delta plane where three degenerate ground states have the largest discontinuities in the magnetization. The discontinuities in the magnetization and bond energy between these ground states are used to calculate the magnetization and specific heat critical exponents and both exponents are found to be near zero.Comment: 10 pages, 6 figures; new references and small changes to tex

Multifractals of Normalized First Passage Time in Sierpinski Gasket

The multifractal behavior of the normalized first passage time is investigated on the two dimensional Sierpinski gasket with both absorbing and reflecting barriers. The normalized first passage time for Sinai model and the logistic model to arrive at the absorbing barrier after starting from an arbitrary site, especially obtained by the calculation via the Monte Carlo simulation, is discussed numerically. The generalized dimension and the spectrum are also estimated from the distribution of the normalized first passage time, and compared with the results on the finitely square lattice.Comment: 10 pages, Latex, with 3 figures and 1 table. to be published in J. Phys. Soc. Jpn. Vol.67(1998

The role of bacterial and algal exopolymeric substances in iron chemistry

© 2015 Elsevier B.V. It is widely accepted that the complexation of iron (Fe) with organic compounds is the primary factor that regulates Fe reactivity and its bioavailability to phytoplankton in the open ocean. Despite considerable efforts to unravel the provenance of the many organic ligands present in the 'ligand soup' and their contribution to Fe chemistry, much of this pool remains largely unresolved. Bacteria and phytoplankton are known to release exopolymeric substances (EPS) for a variety of functions and it is known that this material has metal binding properties. However, the contribution that bacterial and algal EPS makes to Fe biogeochemistry is not well documented. This study revealed that both bacterial and algal EPS contain functional components known to bind Fe (uronic acid, saccharides) and details the molecular weight distribution of the EPS. It is also demonstrated that components of the EPS have a high affinity for Fe-binding, in some cases similar to that of bacterial siderophores (~KFe'L 1012) and that this material greatly enhances Fe solubility (and, possibly, Fe oxyhydroxide reactivity via prevention of aggregation) in seawater. However, EPS may also accelerate Fe(II) oxidation and thus Fe(II) removal from the system. Our findings indicate that, in remote ocean regions, bacterial and algal EPS could play a significant role in the biogeochemical cycling of Fe and their contribution should be considered to further our understanding of the dynamics of Fe-limited oceans

Answering SPARQL queries over databases under OWL 2 QL entailment regime

We present an extension of the ontology-based data access platform Ontop that supports answering SPARQL queries under the OWL 2 QL direct semantics entailment regime for data instances stored in relational databases. On the theoretical side, we show how any input SPARQL query, OWL 2 QL ontology and R2RML mappings can be rewritten to an equivalent SQL query solely over the data. On the practical side, we present initial experimental results demonstrating that by applying the Ontop technologies—the tree-witness query rewriting, T-mappings compiling R2RML mappings with ontology hierarchies, and T-mapping optimisations using SQL expressivity and database integrity constraints—the system produces scalable SQL queries

Innovative treatment modalities for urinary incontinence: a European survey identifying experience and attitude of healthcare providers

Introduction and hypothesis Urinary incontinence is a common condition in women, with a reported prevalence ranging from 25% to 51%. Of these women, an estimated 38% suffer from stress urinary incontinence (SUI). A European research consortium is investigating an innovative system based on information and communication technology for the conservative treatment of women with SUI. When introducing a new intervention, implementation barriers arise and need to be identified. Therefore, we investigated healthcare providers’ experience with and attitude towards innovative care options. Methods We performed an online survey to assess (1) the characteristics and practice of healthcare providers, (2) current protocols for SUI, (3) current use of biofeedback, and (4) knowledge about serious gaming. The survey was sent to members of professional societies in Europe (EUGA), UK (BSUG) and The Netherlands (DPFS). Results Of 341 questionnaires analyzed (response rate between 18% and 30%), 64% of the respondents had access to a protocol for the treatment of SUI, and 31% used biofeedback when treating patients with SUI. However, 92% considered that biofeedback has a clear or probable added value, and 97% of those who did not use biofeedback would change their practice if research evidence supported its use. Finally, 89% of respondents indicated that they had no experience of serious gaming, but 92% considered that it could be useful. Conclusions Although inexperienced, European urogynecologists and physical therapists welcome innovative treatment options for the conservative treatment of SUI such as portable wireless biofeedback and serious gaming. Scientific evidence is considered a prerequisite to incorporate such innovations into clinical practice.Peer ReviewedPostprint (published version

The Computational Complexity of Generating Random Fractals

In this paper we examine a number of models that generate random fractals. The models are studied using the tools of computational complexity theory from the perspective of parallel computation. Diffusion limited aggregation and several widely used algorithms for equilibrating the Ising model are shown to be highly sequential; it is unlikely they can be simulated efficiently in parallel. This is in contrast to Mandelbrot percolation that can be simulated in constant parallel time. Our research helps shed light on the intrinsic complexity of these models relative to each other and to different growth processes that have been recently studied using complexity theory. In addition, the results may serve as a guide to simulation physics.Comment: 28 pages, LATEX, 8 Postscript figures available from [email protected]

On Jacobi Sums in Q(ζp)\mathbb Q(\zeta_p)

We study the p-adic behavior of Jacobi Sums for $\mathbb Q(\zeta_p)$ and link this study to the p-Sylow subgroup of the ideal class group of $\mathbb Q(\zeta_p\`a^+

On the nature of the phase transition in the three-dimensional random field Ising model

A brief survey of the theoretical, numerical and experimental studies of the random field Ising model during last three decades is given. Nature of the phase transition in the three-dimensional RFIM with Gaussian random fields is discussed. Using simple scaling arguments it is shown that if the strength of the random fields is not too small (bigger than a certain threshold value) the finite temperature phase transition in this system is equivalent to the low-temperature order-disorder transition which takes place at variations of the strength of the random fields. Detailed study of the zero-temperature phase transition in terms of simple probabilistic arguments and modified mean-field approach (which take into account nearest-neighbors spin-spin correlations) is given. It is shown that if all thermally activated processes are suppressed the ferromagnetic order parameter m(h) as the function of the strength $h$ of the random fields becomes history dependent. In particular, the behavior of the magnetization curves m(h) for increasing and for decreasing $h$ reveals the hysteresis loop.Comment: 22 pages, 12 figure

Matrix metalloproteinase-10 effectively reduces infarct size in experimental stroke by enhancing fibrinolysis via a thrombin-activatable fibrinolysis inhibitor-mediated mechanism

BACKGROUND: The fibrinolytic and matrix metalloproteinase (MMP) systems cooperate in thrombus dissolution and extracellular matrix proteolysis. The plasminogen/plasmin system activates MMPs, and some MMPs have been involved in the dissolution of fibrin by targeting fibrin(ogen) directly or by collaborating with plasmin. MMP-10 has been implicated in inflammatory/thrombotic processes and vascular integrity, but whether MMP-10 could have a profibrinolytic effect and represent a promising thrombolytic agent is unknown. METHODS AND RESULTS: The effect of MMP-10 on fibrinolysis was studied in vitro and in vivo, in MMP-10-null mice (Mmp10(-/-)), with the use of 2 different murine models of arterial thrombosis: laser-induced carotid injury and ischemic stroke. In vitro, we showed that MMP-10 was capable of enhancing tissue plasminogen activator-induced fibrinolysis via a thrombin-activatable fibrinolysis inhibitor inactivation-mediated mechanism. In vivo, delayed fibrinolysis observed after photochemical carotid injury in Mmp10(-/-) mice was reversed by active recombinant human MMP-10. In a thrombin-induced stroke model, the reperfusion and the infarct size in sham or tissue plasminogen activator-treated animals were severely impaired in Mmp10(-/-) mice. In this model, administration of active MMP-10 to wild-type animals significantly reduced blood reperfusion time and infarct size to the same extent as tissue plasminogen activator and was associated with shorter bleeding time and no intracranial hemorrhage. This effect was not observed in thrombin-activatable fibrinolysis inhibitor-deficient mice, suggesting thrombin-activatable fibrinolysis inhibitor inactivation as one of the mechanisms involved in the MMP-10 profibrinolytic effect. CONCLUSIONS: A novel profibrinolytic role for MMP-10 in experimental ischemic stroke is described, opening new pathways for innovative fibrinolytic strategies in arterial thrombosis