The impact of realistic models of mass segregation on the event rate of extreme-mass ratio inspirals and cusp re-growth

One of the most interesting sources of gravitational waves (GWs) for LISA is the inspiral of compact objects on to a massive black hole (MBH), commonly referred to as an "extreme-mass ratio inspiral" (EMRI). The small object, typically a stellar black hole (bh), emits significant amounts of GW along each orbit in the detector bandwidth. The slowly, adiabatic inspiral of these sources will allow us to map space-time around MBHs in detail, as well as to test our current conception of gravitation in the strong regime. The event rate of this kind of source has been addressed many times in the literature and the numbers reported fluctuate by orders of magnitude. On the other hand, recent observations of the Galactic center revealed a dearth of giant stars inside the inner parsec relative to the numbers theoretically expected for a fully relaxed stellar cusp. The possibility of unrelaxed nuclei (or, equivalently, with no or only a very shallow cusp) adds substantial uncertainty to the estimates. Having this timely question in mind, we run a significant number of direct-summation $N-$body simulations with up to half a million particles to calibrate a much faster orbit-averaged Fokker-Planck code. We then investigate the regime of strong mass segregation (SMS) for models with two different stellar mass components. We show that, under quite generic initial conditions, the time required for the growth of a relaxed, mass segregated stellar cusp is shorter than a Hubble time for MBHs with $M_\bullet \lesssim 5 \times 10^6 M_\odot$ (i.e. nuclei in the range of LISA). SMS has a significant impact boosting the EMRI rates by a factor of $\sim 10$ for our fiducial models of Milky Way type galactic nuclei.Comment: Accepted by CQG, minor changes, a bit expande

Using Pilot Systems to Execute Many Task Workloads on Supercomputers

High performance computing systems have historically been designed to support applications comprised of mostly monolithic, single-job workloads. Pilot systems decouple workload specification, resource selection, and task execution via job placeholders and late-binding. Pilot systems help to satisfy the resource requirements of workloads comprised of multiple tasks. RADICAL-Pilot (RP) is a modular and extensible Python-based pilot system. In this paper we describe RP's design, architecture and implementation, and characterize its performance. RP is capable of spawning more than 100 tasks/second and supports the steady-state execution of up to 16K concurrent tasks. RP can be used stand-alone, as well as integrated with other application-level tools as a runtime system

Innovation reliability and variability strategies: the importance of absorptive capacity on systemic outcomes

The role of absorptive capacity (AC) has been widely recognized in the innovation literature. This study examines the predictive role of AC for business performance, and evaluates the mediation of market orientation (responsive-proactive) and innovation competences orientation (exploitation-exploration) in that relationship. It addresses the gap in the literature on the relative importance of innovation competence orientations versus market orientations. The findings show that innovation competence orientations are more important to business performance than market orientations and that innovation competences are better enhanced by AC than by market orientations. AC is not only confirmed as an antecedent of ambidextrous market and innovation competence orientation, but it also helps directly and indirectly to explain business performance. Responsive market orientation and innovation competence orientation mediate the positive relationship between AC and business performance. The intensity and significance of the indirect effects reveal the specific knowledge-transformative roles of market and innovation competences orientations. Firms seem to mitigate uncertainty by adjusting their preferences toward less risky innovation strategies. Managerial implications highlight the relevance of innovation competences orientation versus market orientation. Furthermore, firms seem to use proactive market orientation ineffectively, a finding that signals a structural marketing handicap.info:eu-repo/semantics/acceptedVersio

Effects of absorptive capacity and innovation spillover on manufacturing flexibility

Shifting demand and ever-shorter production cycles pressure manufacturing flexibility. Although the literature has established the positive effect of the firm’s absorptive capacity on manufacturing flexibility, the separate role of the innovation competencies of exploitation and exploration in such a relationship is still under-investigated. In this study, we examine how these competencies affect manufacturing flexibility. We use survey data from 370 manufacturing firms and analyze them using covariance-based structural equation modeling (CB-SEM). The results indicate that absorptive capacity has a strong, positive, and direct effect on exploitative and exploratory innovation competencies, proactive and responsive market orientations, and manufacturing flexibility. Our findings also demonstrate that the exploratory innovation competencies mediate the relation between responsive market orientation and manufacturing flexibility. Essentially, these exploitative innovation competencies produce a direct positive effect on manufacturing flexibility while simultaneously being a vehicle for absorptive capacity’s indirect effects on it. An exploration innovation strategy does not significantly affect manufacturing flexibility. This study contributes by combining key strategic features of firms with manufacturing flexibility, while providing new empirical evidence of the mediation of the exploratory innovation competencies in the relation between responsive market orientation and manufacturing flexibility.info:eu-repo/semantics/acceptedVersio

Fostering knowledge creation to improve performance: the mediation role of manufacturing flexibility

Purpose This study examines the mediating role of manufacturing flexibility in the relationship between knowledge creation, technological turbulence, and performance. In an increasingly competitive and changing environment, firms need to boost their technological and management know-how to adequately develop manufacturing flexibility. Design/methodology/approach The study analyzes survey data collected from 370 manufacturing firms. Validity and reliability analyses were conducted using SPSS and Amos. The research hypotheses were tested using covariance-based structural equation modeling. Findings The main findings show that knowledge creation positively and significantly affects business and operational performances directly, and indirectly, through manufacturing flexibility. Moreover, technological turbulence has a positive and significant effect on it. This finding contributes to understanding why some firms get better outcomes from manufacturing flexibility than others, a disputed issue in the literature. Practical implications This study highlights the need for manufacturing firms to foster cultures of knowledge creation, to better educate and train employees, and to develop other instruments of knowledge creation. Originality/value This study makes several contributions to manufacturing flexibility literature: (i) establishing a link between technological turbulence and knowledge creation develop manufacturing flexibility; (ii) add empirical evidence on the relation between manufacturing flexibility and performance; (iii) contributes to consolidating the mediation role of manufacturing flexibility in the relations between knowledge creation and business performance, as studies focusing on such a role are scarce in the literature.info:eu-repo/semantics/acceptedVersio

Assessing the impact of universities’ entrepreneurial activity on regional competitiveness

The aim of this study is to test the multidimensional construct of the Entrepreneurial University (EU), and therefore to confirm whether EU factors make a positive contribution to regional competitiveness. Data were collected from ten Portuguese Public Universities (PPUs) through a self-administered questionnaire. First- and second-order confirmatory factor analyses (CFA) were performed through factor and multiple linear regression analyses. The main findings show that EU related factors—perceived and combined with actual regional metrics—especially entrepreneurial supporting measures, positively contributed to regional competitiveness. This study shows policy makers that universities are not merely cost centres but provide knowledge spillovers that can have a positive influence on regional competitiveness.info:eu-repo/semantics/publishedVersio

Novel benzo[α]phenoxazinium chlorides functionalized with sulfonamide groups as NIR fluorescent probes for vacuole, endoplasmic reticulum, and plasma membrane staining

The demand for new fluorophores for different biological target imaging is increasing. Benzo[a]phenoxazine derivatives are fluorochromophores that show promising optical properties for bioimaging, namely fluorescent emission at the NIR of the visible region, where biological samples have minimal fluorescence emission. In this study, six new benzo[a]phenoxazinium chlorides possessing sulfonamide groups at 5-amino-positions were synthesized and their optical and biological properties were tested. Compared with previous probes evaluated using fluorescence microscopy, using different S. cerevisiae strains, these probes, with sulfonamide groups, stained the vacuole membrane and/or the perinuclear membrane of the endoplasmic reticulum with great specificity, with some fluorochromophores capable of even staining the plasma membrane. Thus, the addition of a sulfonamide group to the benzo[a]phenoxazinium core increases their specificity and attributes for the fluorescent labeling of cell applications and fractions, highlighting them as quite valid alternatives to commercially available dyes.FCT (Fundação para a Ciência e Tecnologia, Portugal) and FEDER (European Fund for Regional Development)-COMPETEQREN-EU for financial support to the research centers CQ/UM (UID/QUI/00686/2021), and CBMA (Ref. UIDB/04050/2020), as well as a PhD grant to J. C. Ferreira (SFRH/BD/133207/2017 and COVID/BD/151978/2021). The NMR spectrometer Bruker Avance III 400 (part of the National NMR Network) was financed by FCT and FEDER

Ruthenium-cyclopentadienyl bipyridine-biotin based compounds: Synthesis and biological effect

Prospective anticancer metallodrugs should consider target-specific components in their design in order to overcome the limitations of the current chemotherapeutics. The inclusion of vitamins, which receptors are overexpressed in many cancer cell lines, has proven to be a valid strategy. Therefore, in this paper we report the synthesis and characterization of a set of new compounds [Ru(eta(5)-C5H5)(P(C6H4R)(3))(4,4'-R'-2,2'-bpy)](+) (R = F and R' = H, 3; R = F and R' = biotin, 4; R = OCH3 and R' = H, 5; R = OCH3 and R' = biotin, 6), inspired by the exceptional good results recently obtained for the analogue bearing a triphenylphosphane ligand. The precursors for these syntheses were also described following modified literature procedures, [Ru(eta(5)-C5H3)(P(C6H4R)(3))(2)Cl], where R is -F (1) or -OCH3 (2). The structure of all compounds is fully supported by spectroscopic and analytical techniques and by X-ray diffraction studies for compounds 2, 3, and 5. All cationic compounds are cytotoxic in the two breast cancer cell lines tested, MCF7 and MDA-MB-231, and much better than cisplatin under the same experimental conditions. The cytotoxicity of the biotinylated compounds seems to be related with the Ru uptake by the cells expressing biotin receptors, indicating a potential mediated uptake. Indeed, a biotin-avidin study confirmed that the attachment of biotin to the organometallic fragment still allows biotin recognition by the protein. Therefore, the biotinylated compounds might be potent anticancer drugs as they show cytotoxic effect in breast cancer cells at low dose dependent on the compounds' uptake, induce cell death by apoptosis and inhibit the colony formation of cancer cells causing also less severe side effects in zebrafish.This work was financed by the Portuguese Foundation for Science and Technology (Fundacao para a Crencia e Tecnologia, FCT) within the scope of Projects UID/QUI/00100/2019 and PTDC/QUI-QIN/28662/2017. This work was supported by the strategic program UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through the FCT I.P. and by the ERDF through the COMPETE2020 -Programa Operacional Competitividade e Intemacionalizacao (POCI). A.V. acknowledges the Investigator FCT2013 Initiative for the Project IF/01302/2013 and CEEC-IND/01974/2017 (acknowledging FCT, as well as POPH and FSE, the European Social Fund). L.C.-R, A.R.B. and A.P. thank FCT for their Ph.D. Grants (SFRH/BD/100515/2014, SFRH/BD/139271/2018, and SFRH/BD/139412/2018, respectively). L.C.-R also acknowledges Fulbright Research Grant 2017/2018 with the support of FCT. Brittany Karas acknowledges NJAES-RutgersNJ01201 and NIEHS Training Grant T32-ES 007148 and B.T.B. and C.D. acknowledge NIH-NIEHS P30 ES005022. K.R.C. acknowledges NJAES Project 01202 (W2045) and NIH ES005022

Pulsar timing arrays and the challenge of massive black hole binary astrophysics

Pulsar timing arrays (PTAs) are designed to detect gravitational waves (GWs) at nHz frequencies. The expected dominant signal is given by the superposition of all waves emitted by the cosmological population of supermassive black hole (SMBH) binaries. Such superposition creates an incoherent stochastic background, on top of which particularly bright or nearby sources might be individually resolved. In this contribution I describe the properties of the expected GW signal, highlighting its dependence on the overall binary population, the relation between SMBHs and their hosts, and their coupling with the stellar and gaseous environment. I describe the status of current PTA efforts, and prospect of future detection and SMBH binary astrophysics.Comment: 18 pages, 4 figures. To appear in the Proceedings of the 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

Massive binary black holes in galactic nuclei and their path to coalescence

Massive binary black holes form at the centre of galaxies that experience a merger episode. They are expected to coalesce into a larger black hole, following the emission of gravitational waves. Coalescing massive binary black holes are among the loudest sources of gravitational waves in the Universe, and the detection of these events is at the frontier of contemporary astrophysics. Understanding the black hole binary formation path and dynamics in galaxy mergers is therefore mandatory. A key question poses: during a merger, will the black holes descend over time on closer orbits, form a Keplerian binary and coalesce shortly after? Here we review progress on the fate of black holes in both major and minor mergers of galaxies, either gas-free or gas-rich, in smooth and clumpy circum-nuclear discs after a galactic merger, and in circum-binary discs present on the smallest scales inside the relic nucleus.Comment: Accepted for publication in Space Science Reviews. To appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher