147 research outputs found

    The dynamics of the non-heme iron in bacterial reaction centers from Rhodobacter sphaeroides

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    AbstractWe investigate the dynamical properties of the non-heme iron (NHFe) in His-tagged photosynthetic bacterial reaction centers (RCs) isolated from Rhodobacter (Rb.) sphaeroides. Mössbauer spectroscopy and nuclear inelastic scattering of synchrotron radiation (NIS) were applied to monitor the arrangement and flexibility of the NHFe binding site. In His-tagged RCs, NHFe was stabilized only in a high spin ferrous state. Its hyperfine parameters (IS=1.06±0.01mm/s and QS=2.12±0.01mm/s), and Debye temperature (θD0~167K) are comparable to those detected for the high spin state of NHFe in non-His-tagged RCs. For the first time, pure vibrational modes characteristic of NHFe in a high spin ferrous state are revealed. The vibrational density of states (DOS) shows some maxima between 22 and 33meV, 33 and 42meV, and 53 and 60meV and a very sharp one at 44.5meV. In addition, we observe a large contribution of vibrational modes at low energies. This iron atom is directly connected to the protein matrix via all its ligands, and it is therefore extremely sensitive to the collective motions of the RC protein core. A comparison of the DOS spectra of His-tagged and non-His-tagged RCs from Rb. sphaeroides shows that in the latter case the spectrum was overlapped by the vibrations of the heme iron of residual cytochrome c2, and a low spin state of NHFe in addition to its high spin one. This enabled us to pin-point vibrations characteristic for the low spin state of NHFe

    The Concept of Sustainable Development and Its Impact on the Shaping of Modern International Relations through Global Agreements

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    The goal of this article is a depiction of the process of the molding of the concept of sustainable development as well as a look at the influence that this concept has exerted on contemporary international politics, especially taking into account agreements of worldwide scope. This article is also an effort at demonstrating that the foundations of the concept of sustainable development can be traced to certain economic theories. The final section of this article is devoted to the characteristics of individual conferences initiated by the United Nations in order to promote enduring and sustainable development on a world scale. Also presented are the achievements of the individual conferences and their roles in demarcating universally obligatory principles and standards of sustainable development.Celem niniejszego artykułu jest scharakteryzowanie genezy kształtowania się Koncepcji Zrównoważonego Rozwoju, a także wskazanie, jaki wpływ miała ona na ukształtowanie się stosunków międzynarodowych w zakresie ochrony środowiska i rozwiązywania problemów społecznych. Przedmiotem analizy są także teorie ekonomiczne, które stały się fundamentem dla wykrystalizowania się koncepcji zrównoważonego rozwoju. Poniższy artykuł jest także próbą wykazania, iż konferencje organizowane przez ONZ na rzecz trwałego i zrównoważonego rozwoju, stały się siła napędową do rozpowszechnienia tej koncepcji w skali światowej

    Differences in the Quality of Pediatric Resuscitative Care Across a Spectrum of Emergency Departments

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    Importance: The quality of pediatric resuscitative care delivered across the spectrum of emergency departments (EDs) in the United States is poorly described. In a recent study, more than 4000 EDs completed the Pediatric Readiness Survey (PRS); however, the correlation of PRS scores with the quality of simulated or real patient care has not been described. Objective: To measure and compare the quality of resuscitative care delivered to simulated pediatric patients across a spectrum of EDs and to examine the correlation of PRS scores with quality measures. Design, Setting, and Participants: This prospective multicenter cohort study evaluated 58 interprofessional teams in their native pediatric or general ED resuscitation bays caring for a series of 3 simulated critically ill patients (sepsis, seizure, and cardiac arrest). Main Outcomes and Measures: A composite quality score (CQS) was measured as the sum of 4 domains: (1) adherence to sepsis guidelines, (2) adherence to cardiac arrest guidelines, (3) performance on seizure resuscitation, and (4) teamwork. Pediatric Readiness Survey scores and health care professional demographics were collected as independent data. Correlations were explored between CQS and individual domain scores with PRS. Results: Overall, 58 teams from 30 hospitals participated (8 pediatric EDs [PEDs], 22 general EDs [GEDs]). The mean CQS was 71 (95% CI, 68-75); PEDs had a higher mean CQS (82; 95% CI, 79-85) vs GEDs (66; 95% CI, 63-69) and outperformed GEDs in all domains. However, when using generalized estimating equations to estimate CQS controlling for clustering of the data, PED status did not explain a higher CQS (beta = 4.28; 95% CI, -4.58 to 13.13) while the log of pediatric patient volume did explain a higher CQS (beta = 9.57; 95% CI, 2.64-16.49). The correlation of CQS to PRS was moderate (r = 0.51; P \u3c .001). The correlation was weak for cardiac arrest (r = 0.24; P = .07), weak for sepsis (rho = 0.45; P \u3c .001) and seizure (rho = 0.43; P = .001), and strong for teamwork (rho = 0.71; P \u3c .001). Conclusions and Relevance: This multicenter study noted significant differences in the quality of simulated pediatric resuscitative care across a spectrum of EDs. The CQS was higher in PEDs compared with GEDs. However, when controlling for pediatric patient volume and other variables in a multivariable model, PED status does not explain a higher CQS while pediatric patient volume does. The correlation of the PRS was moderate for simulation-based measures of quality

    Emerging interdependence between stock values during financial crashes

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    To identify emerging interdependencies between traded stocks we investigate the behavior of the stocks of FTSE 100 companies in the period 2000-2015, by looking at daily stock values. Exploiting the power of information theoretical measures to extract direct influences between multiple time series, we compute the information flow across stock values to identify several different regimes. While small information flows is detected in most of the period, a dramatically different situation occurs in the proximity of global financial crises, where stock values exhibit strong and substantial interdependence for a prolonged period. This behavior is consistent with what one would generally expect from a complex system near criticality in physical systems, showing the long lasting effects of crashes on stock markets

    Inference of financial networks using the normalised mutual information rate

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    In this paper we study data from financial markets using an information theory tool that we call the normalised Mutual Information Rate and show how to use it to infer the underlying network structure of interrelations in foreign currency exchange rates and stock indices of 14 countries world-wide and the European Union. We first present the mathematical method and discuss about its computational aspects, and then apply it to artificial data from chaotic dynamics and to correlated random variates. Next, we apply the method to infer the network structure of the financial data. Particularly, we study and reveal the interrelations among the various foreign currency exchange rates and stock indices in two separate networks for which we also perform an analysis to identify their structural properties. Our results show that both are small-world networks sharing similar properties but also having distinct differences in terms of assortativity. Finally, the consistent relationships depicted among the 15 economies are further supported by a discussion from the economics view point

    Obstacles on the way to the clinical visualisation of beta cells: looking for the Aeneas of molecular imaging to navigate between Scylla and Charybdis

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    For more than a decade, researchers have been trying to develop non-invasive imaging techniques for the in vivo measurement of viable pancreatic beta cells. However, in spite of intense research efforts, only one tracer for positron emission tomography (PET) imaging is currently under clinical evaluation. To many diabetologists it may remain unclear why the imaging world struggles to develop an effective method for non-invasive beta cell imaging (BCI), which could be useful for both research and clinical purposes. Here, we provide a concise overview of the obstacles and challenges encountered on the way to such BCI, in both native and transplanted islets. We discuss the major difficulties posed by the anatomical and cell biological features of pancreatic islets, as well as the chemical and physical limits of the main imaging modalities, with special focus on PET, SPECT and MRI. We conclude by indicating new avenues for future research in the field, based on several remarkable recent results

    Coral microbiome composition along the northern Red Sea suggests high plasticity of bacterial and specificity of endosymbiotic dinoflagellate communities

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    Background The capacity of reef-building corals to tolerate (or adapt to) heat stress is a key factor determining their resilience to future climate change. Changes in coral microbiome composition (particularly for microalgal endosymbionts and bacteria) is a potential mechanism that may assist corals to thrive in warm waters. The northern Red Sea experiences extreme temperatures anomalies, yet corals in this area rarely bleach suggesting possible refugia to climate change. However, the coral microbiome composition, and how it relates to the capacity to thrive in warm waters in this region, is entirely unknown. Results We investigated microbiomes for six coral species (Porites nodifera, Favia favus, Pocillopora damicornis, Seriatopora hystrix, Xenia umbellata, and Sarcophyton trocheliophorum) from five sites in the northern Red Sea spanning 4° of latitude and summer mean temperature ranges from 26.6 °C to 29.3 °C. A total of 19 distinct dinoflagellate endosymbionts were identified as belonging to three genera in the family Symbiodiniaceae (Symbiodinium, Cladocopium, and Durusdinium). Of these, 86% belonged to the genus Cladocopium, with notably five novel types (19%). The endosymbiont community showed a high degree of host-specificity despite the latitudinal gradient. In contrast, the diversity and composition of bacterial communities of the surface mucus layer (SML)—a compartment particularly sensitive to environmental change—varied significantly between sites, however for any given coral was species-specific. Conclusion The conserved endosymbiotic community suggests high physiological plasticity to support holobiont productivity across the different latitudinal regimes. Further, the presence of five novel algal endosymbionts suggests selection of certain genotypes (or genetic adaptation) within the semi-isolated Red Sea. In contrast, the dynamic composition of bacteria associated with the SML across sites may contribute to holobiont function and broaden the ecological niche. In doing so, SML bacterial communities may aid holobiont local acclimatization (or adaptation) by readily responding to changes in the host environment. Our study provides novel insight about the selective and endemic nature of coral microbiomes along the northern Red Sea refugia
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