548 research outputs found
Discrimination capacity in species distribution models depends on the representativeness of the environmental domain
Aim When faced with dichotomous events, such as the presence or absence of a
species, discrimination capacity (the ability to separate the instances of presence
from the instances of absence) is usually the only characteristic that is assessed in
the evaluation of the performance of predictive models. Although neglected, calibration
or reliability (how well the estimated probability of presence represents the
observed proportion of presences) is another aspect of the performance of predictive
models that provides important information. In this study, we explore how
changes in the distribution of the probability of presence make discrimination
capacity a context-dependent characteristic of models. For the first time,we explain
the implications that ignoring the context dependence of discrimination can have
in the interpretation of species distribution models
Factors affecting SMEs' strategic decisions to approach international markets
[EN] The internationalisation challenges that face all companies are no longer the exclusive concern of multinationals. Participation in the international marketplace has become a reality for large firms and small and medium-sized enterprises (SME) alike. This kind of participation can be rewarding for both companies and employees. The markets that SMEs enter and the success of this entry depend on several factors such as cultural differences, company tradition, venture capital, products and competitors. The goal of this study is therefore to understand whether the characteristics of the external market, the characteristics of the company itself and the barriers to internationalisation influence the strategic approach that SMEs adopt in their internationalisation processes. Using data on 320 Portuguese SMEs, we apply multivariate analyses to test the dimensions of internationalisation. We find that the decision of SMEs to internationalise involves an institutional change in response to external pressures in the home country. SMEs under greater institutional pressure not only tend to expand further but also engage in their initial international activities more radically.This work is supported by FEDER funds from COMPETE 2020 and Portuguese funds -
PORTUGAL 2020. Project IEcPBI - Interactive Ecosystem for Portuguese Business
Internationalization - POCI-01-0145-FEDER-032139.Azevedo Lobo, C.; Fernandes, CI.; Ferreira, JJ.; Peris-Ortiz, M. (2020). Factors affecting SMEs' strategic decisions to approach international markets. European J of International Management. 14(4):617-639. https://doi.org/10.1504/EJIM.2020.107607S61763914
Are species occurrence data in global online repositories fit for modeling species distributions? The case of the Global Biodiversity Information Facility (GBIF). Final Report of the Task Group on GBIF Data Fitness for Use in Distribution Modelling.
Primary Biodiversity Data (PBD) are defined as the basic attributes of observations or records of the occurrences of species. PBD is a fundamental concept of biodiversity informatics since it is substantial in quantity and provides the links to organize other large and independent bodies of data concerning species (= taxonomic information) and environments. In fact, PBD is at the core of the exploding field of biodiversity informatics, which in some sense now underlies biogeography, macroecology, landscape ecology and several other subdisciplines of biology.
A principal - and rapidly growing - class of research that can be performed using PBD is the estimation of a species' environmental requirements and the projection of these in both environmental and geographic spaces to estimate niches or distributional ranges, generally by using models of ecological niches and species' distributions (often called ENMs or SDMs, respectively).
The largest point of access to PBD in the world is the Global Biodiversity Information Facility (GBIF), and hundreds of papers have now used GBIF-mediated data to fit and apply ENM/SDM.
Experience has shown that GBIF, like other aggregated data research infrastructures, holds a number of potential problems related to incomplete or difficult access to all the fields in its schema, inconsistent information among fields, or simply erroneous or incomplete data. These drawbacks complicate ENM/SDM analyses considerably, and detract from the enormous scientific value of this information storehouse.
Three overlapping communities participate in GBIF's data process: providers (museums, herbaria, and observer's networks), users (scientists, analysts working for governments, NGOs or the private sector, the public) and the technical staff managing the huge databases, web services and servers at GBIF. Each can play a different role in fixing data issues of GBIF.
Our main recommendations for the GBIF Secretariat are the following:
GBIF.org should serve indicators of precision, quality, and uncertainty of data that can be calculated practically, and preferably "on the fly", as well as summaries and metrics of completeness of inventories, at scales and for regions defined by the user. The summaries should display maps and graphs of completeness by region, time-period and taxa.
The implementation of the GBIF information resource should go beyond unique identifiers of queries (DOIs for downloads, including the capability to re-run queries, http://www.gbif.org/publishing-data/summary#supporteddatasettypes), and to include identifiers of the individual data that make up the queried data.
GBIF.org should include applications or functionalities enabling users to annotate errors or problems, and communicate those changes directly to providers, as it may be practical and appropriate. This point may need to be discussed with providers.
A procedure enabling users to make accessible versions of their databases that have been improved and annotated should be supported, but this functionality should not lose the vital tie back to the original data records and the actual data provider.
GBIF should partner with and/or support initiatives to do more for training and guiding users on the proper use of the data; such initiatives should incorporate actual expert uses in ENM/SDM to assure that current best practices are followed
RNA-seq based transcriptome analysis of the type I interferon host response upon vaccinia virus infection of mouse cells
Vaccinia virus (VACV) encodes the soluble type I interferon (IFN) binding protein B18 that is secreted from infected cells and also attaches to the cell surface, as an immunomodulatory strategy to inhibit the host IFN response. By using next generation sequencing technologies, we performed a detailed RNA-seq study to dissect at the transcriptional level the modulation of the IFN based host response by VACV and B18. Transcriptome profiling of L929 cells after incubation with purified recombinant B18 protein showed that attachment of B18 to the cell surface does not trigger cell signalling leading to transcriptional activation. Consistent with its ability to bind type I IFN, B18 completely inhibited the IFN-mediated modulation of host gene expression. Addition of UV-inactivated virus particles to cell cultures altered the expression of a set of 53 cellular genes, including genes involved in innate immunity. Differential gene expression analyses of cells infected with replication competent VACV identified the activation of a broad range of host genes involved in multiple cellular pathways. Interestingly, we did not detect an IFN-mediated response among the transcriptional changes induced by VACV, even after the addition of IFN to cells infected with a mutant VACV lacking B18. This is consistent with additional viral mechanisms acting at different levels to block IFN responses during VACV infection
Signature of stripe pinning in optical conductivity
The response of charge stripes to an external electric field applied
perpendicular to the stripe direction is studied within a diagrammatic approach
for both weak and strong pinning by random impurities. The sound-like mode of
the stripes described as elastic strings moves to finite frequency due to
impurity pinning. By calculating the optical conductivity we determine this
characteristic energy scale for both a single stripe and an array of
interacting stripes. The results explain the anomalous far-infrared peak
observed recently in optical-conductivity measurements on cuprates.Comment: Revised version, to appear in Phys. Rev.
Patient Centric Pharmaceutical Drug Product Design—The Impact on Medication Adherence
Medication adherence is a growing concern for public health and poor adherence to therapy has been associated with poor health outcomes and higher costs for patients. Interventions for improving adherence need to consider the characteristics of the individual therapeutic regimens according to the needs of the patients. In particular, geriatric and paediatric populations as well as dermatological patients have special needs/preferences that should be considered when designing drug products. Patient Centric Drug Product Pharmaceutical Design (PCDPD) offers the opportunity to meet the needs and preferences of patients. Packaging, orodispersible formulations, fixed dose combinations products, multiparticulate formulations, topical formulations and 3D printing are of particular relevance in a PCDPD process. These will be addressed in this review as well as their impact on medication adherence
Anisotropic dark energy stars
A model of compact object coupled to inhomogeneous anisotropic dark energy is
studied. It is assumed a variable dark energy that suffers a phase transition
at a critical density. The anisotropic Lambda-Tolman-Oppenheimer-Volkoff
equations are integrated to know the structure of these objects. The anisotropy
is concentrated on a thin shell where the phase transition takes place, while
the rest of the star remains isotropic. The family of solutions obtained
depends on the coupling parameter between the dark energy and the fermion
matter. The solutions share several features in common with the gravastar
model. There is a critical coupling parameter that gives non-singular black
hole solutions. The mass-radius relations are studied as well as the internal
structure of the compact objects. The hydrodynamic stability of the models is
analyzed using a standard test from the mass-radius relation. For each
permissible value of the coupling parameter there is a maximum mass, so the
existence of black holes is unavoidable within this model.Comment: 12 pages, 6 figures, final manuscript, Accepted for publication in
Astrophysics & Space Scienc
Effect of two different pulses of Shewanella putrefaciens Pdp11 on Solea senegalensis larvae performance
Star Models with Dark Energy
We have constructed star models consisting of four parts: (i) a homogeneous
inner core with anisotropic pressure (ii) an infinitesimal thin shell
separating the core and the envelope; (iii) an envelope of inhomogeneous
density and isotropic pressure; (iv) an infinitesimal thin shell matching the
envelope boundary and the exterior Schwarzschild spacetime. We have analyzed
all the energy conditions for the core, envelope and the two thin shells. We
have found that, in order to have static solutions, at least one of the regions
must be constituted by dark energy. The results show that there is no physical
reason to have a superior limit for the mass of these objects but for the ratio
of mass and radius.Comment: 20 pages, 1 figure, references and some comments added, typos
corrected, in press GR
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