| 1. |
- Algaba, Juan-Carlos, et al.
(författare)
-
Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
-
Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
|
|
| 2. |
- Klionsky, Daniel J., et al.
(författare)
-
Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
-
Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
-
Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
|
|
| 3. |
- Hudson, Lawrence N, et al.
(författare)
-
The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
-
Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
-
Tidskriftsartikel (refereegranskat)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
|
|
| 4. |
- Backes, Claudia, et al.
(författare)
-
Production and processing of graphene and related materials
- 2020
-
Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results. Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs,
|
|
| 5. |
- Wallace, Stephanie E., et al.
(författare)
-
MYLK pathogenic variants aortic disease presentation, pregnancy risk, and characterization of pathogenic missense variants
- 2019
-
Ingår i: Genetics in Medicine. - : Nature Publishing Group. - 1098-3600 .- 1530-0366. ; 21:1, s. 144-151
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Heritable thoracic aortic disease can result from null variants in MYLK, which encodes myosin light-chain kinase (MLCK). Data on which MYLKmissense variants are pathogenic and information to guide aortic disease management are limited.Methods: Clinical data from 60 cases with MYLK pathogenic variants were analyzed (five null and two missense variants), and the effect of missense variants on kinase activity was assessed.Results: Twenty-three individuals (39%) experienced an aortic event (defined as aneurysm repair or dissection); the majority of these events (87%) were aortic dissections. Aortic diameters were minimally enlarged at the time of dissection in many cases. Time-to-aortic-event curves showed that missense pathogenic variant (PV) carriers have earlier-onset aortic events than null PV carriers. An MYLK missense variant segregated with aortic disease over five generations but decreases MYLK kinase acitivity marginally. Functional Assays fail to identify all pathogenic variants in MYLK.Conclusion: These data further define the aortic phenotype associated with MYLKpathogenic variants. Given minimal aortic enlargement before dissection, an alternative approach to guide the timing of aortic repair is proposed based on the probability of a dissection at a given age.
|
|
| 6. |
- Colombo, Roberto M., et al.
(författare)
-
Low-cost SDR-based Tool for Evaluating LoRa Satellite Communications
- 2022
-
Ingår i: 2022 IEEE International Symposium on Measurements and Networking, M and N 2022 - Proceedings. - : IEEE conference proceedings. - 9781665483629
-
Konferensbidrag (refereegranskat)abstract
- LoRa (Long Range) technology, with great success in providing coverage for massive Internet-of-things (IoT) deployments, is recently being considered to complement the terrestrial networks with Low Earth Orbit (LEO) satellite connectivity. The objective is to extend coverage to remote areas for various verticals, such as logistics, asset tracking, transportation, utilities, agriculture, and maritime. However, only limited studies have realistically evaluated the effects of ground-to-satellite links due to the high cost of traditional tools and methods to emulate the radio channel. In this paper, compared to an expensive channel emulator, we propose and develop an alternative method for the experimental study of LoRa satellite links using lower-cost software defined radio (SDR). Since the working details of LoRa modulation are limited to the reverse-engineered imitations, we employ such a version on SDR platform and add easily controllable adverse channel effects to evaluate LoRa for satellite connectivity. In our work, the emulation of the Doppler effect is considered as a key aspect for testing the reliability of LoRa satellite links. Therefore, after demonstrating the correctness of the (ideal) L oRa transceiver implementation, achieving a low packet error ratio (PER) with a commercial L oRa receiver, the baseband signal is distorted to emulate the Doppler effect, mimicking a real LoRa satellite communication. The Doppler effect is related to time-on-air (ToA), bounded to communication parameters and orbit height. Higher ToAs and lower orbits decrease the link duration, mainly because of dynamic Doppler effect.
|
|
| 7. |
- Farooq, Vasim, et al.
(författare)
-
Incidence and multivariable correlates of long-term mortality in patients treated with surgical or percutaneous revascularization in the Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) trial.
- 2012
-
Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 33:24, s. 3105-3113
-
Tidskriftsartikel (refereegranskat)abstract
- Aims The aim of this investigation was to determine the incidence and multivariable correlates of long-term (4-year) mortality in patients treated with surgical or percutaneous revascularization in the synergy between percutaneous coronary intervention (PCI) with TAXUS Express and Cardiac Surgery (SYNTAX) trial. Methods and results A total of 1800 patients were randomized to undergo coronary artery bypass graft (CABG) surgery (n = 897) or PCI (n = 903). Prospectively collected baseline and peri- and post-procedural data were used to determine independent correlates of 4-year all-cause death in the CABG and the PCI arms (Cox proportional hazards model). Four-year mortality rates in the CABG and the PCI arms were 9.0% [74 deaths (12 in-hospital)] and 11.8% [104 deaths (16 in-hospital)], respectively (log-rank P-value = 0.063). Censored data comprised 78 patients (8.7%) in the CABG arm, and 24 patients (2.7%) in the PCI arm (log-rank P-value < 0.001). Within the CABG arm, the strongest independent correlates of 4-year mortality were lack of discharge aspirin [hazard ratio (HR) 3.56; 95% CI: 2.04, 6.21; P < 0.001], peripheral vascular disease (PVD) (HR: 2.65; 95% CI: 1.49, 4.72; P = 0.001), chronic obstructive pulmonary disease, age, and serum creatinine. Within the PCI arm, the strongest independent correlate of 4-year mortality was lack of post-procedural anti-platelet therapy (HR: 152.16; 95% CI: 53.57, 432.22; P < 0.001), with 10 reported early (within 45 days) in-hospital deaths secondary to multifactorial causes precluding administration of anti-platelet therapy. Other independent correlates of mortality in the PCI arm included amiodarone therapy on discharge, pre-procedural poor left ventricular ejection fraction, a 'history of gastrointestinal bleeding or peptic ulcer disease', PVD (HR: 2.13; 95% CI: 1.26, 3.60; P = 0.005), age, female gender (HR: 1.60; 95% CI: 1.01, 2.56; P = 0.048), and the SYNTAX score (Per increase in 10 points: HR: 1.25; 95% CI: 1.06, 1.47; P = 0.007). Conclusion Independent correlates of 4-year mortality in the SYNTAX trial were multifactorial. Lack of discharge aspirin and lack of post-procedural anti-platelet therapy were the strongest independent correlates of mortality in the CABG and the PCI arms, respectively. Peripheral vascular disease is a common independent correlate of 4-year mortality and may be a marker of the severity of baseline coronary disease and risk of future native coronary disease (and extra-cardiac disease) progression.
|
|
| 8. |
|
|
| 9. |
- Farooq, Vasim, et al.
(författare)
-
The Negative Impact of Incomplete Angiographic Revascularization on Clinical Outcomes and Its Association With Total Occlusions : The SYNTAX (Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) Trial
- 2013
-
Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 61:3, s. 282-294
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES:The study sought to evaluate the clinical impact of angiographic complete (CR) and incomplete (ICR) revascularization and its association with the presence of total occlusions (TO), after percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery in the "all-comers" SYNTAX (Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) trial.BACKGROUND:In patients with complex coronary artery disease undergoing PCI or CABG, the long-term prognostic implications of CR versus ICR is unsettled.METHODS:In this post hoc study, consisting of randomized (n = 1,800) and nested PCI (n = 198) and CABG (n = 649) registries, 4-year clinical outcomes were compared in groups, with and without angiographic CR, in the PCI and CABG arms. Clinical outcomes were analyzed with Kaplan-Meier estimates, log-rank comparisons, and Cox regression analyses. Multivariate predictors of ICR were determined. Similar analyses were undertaken in the TO and non-TO treated groups of both study arms.RESULTS:Angiographic CR was achieved in 52.8% of the PCI arm and 66.9% of the CABG arm. Within the PCI and CABG arms, ICR (compared with CR) seemed to be a surrogate marker of a greater burden of anatomical coronary complexity and clinical comorbidity and was associated with significantly higher frequencies of 4-year mortality, all-cause revascularization, stent thrombosis (PCI arm), and major adverse cardiac and cerebrovascular events. The presence of a TO was the strongest independent predictor of ICR after PCI (hazard ratio: 2.70, 95% confidence interval: 1.98 to 3.67, p < 0.001). Eight hundred and forty patients (PCI: 26.3%, CABG: 36.4%, p < 0.001) were identified to have 1,007 TOs, with 68.1% of TOs located in the proximal-mid coronary vasculature. The findings associating ICR (compared with CR) with higher frequencies of 4-year mortality and major adverse cardiac and cerebrovascular events remained consistent in the TO-treated groups in the PCI and CABG arms.CONCLUSIONS:Within the PCI and CABG arms of the all-comers SYNTAX trial, angiographically determined ICR has a detrimental impact on long-term clinical outcomes, including mortality. This effect remained consistent in patients with and without TOs.
|
|
| 10. |
- Migliavacca, Mirco, et al.
(författare)
-
Semiempirical modeling of abiotic and biotic factors controlling ecosystem respiration across eddy covariance sites
- 2011
-
Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 17:1, s. 390-409
-
Tidskriftsartikel (refereegranskat)abstract
- In this study we examined ecosystem respiration (R-ECO) data from 104 sites belonging to FLUXNET, the global network of eddy covariance flux measurements. The goal was to identify the main factors involved in the variability of R-ECO: temporally and between sites as affected by climate, vegetation structure and plant functional type (PFT) (evergreen needleleaf, grasslands, etc.). We demonstrated that a model using only climate drivers as predictors of R-ECO failed to describe part of the temporal variability in the data and that the dependency on gross primary production (GPP) needed to be included as an additional driver of R-ECO. The maximum seasonal leaf area index (LAI(MAX)) had an additional effect that explained the spatial variability of reference respiration (the respiration at reference temperature T-ref=15 degrees C, without stimulation introduced by photosynthetic activity and without water limitations), with a statistically significant linear relationship (r2=0.52, P < 0.001, n=104) even within each PFT. Besides LAI(MAX), we found that reference respiration may be explained partially by total soil carbon content (SoilC). For undisturbed temperate and boreal forests a negative control of total nitrogen deposition (N-depo) on reference respiration was also identified. We developed a new semiempirical model incorporating abiotic factors (climate), recent productivity (daily GPP), general site productivity and canopy structure (LAI(MAX)) which performed well in predicting the spatio-temporal variability of R-ECO, explaining > 70% of the variance for most vegetation types. Exceptions include tropical and Mediterranean broadleaf forests and deciduous broadleaf forests. Part of the variability in respiration that could not be described by our model may be attributed to a series of factors, including phenology in deciduous broadleaf forests and management practices in grasslands and croplands.
|
|
