564 research outputs found

    Ultraluminous Quasars At High Redshift Show Evolution In Their Radio-Loudness Fraction In Both Redshift And Ultraviolet Luminosity

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    We take a sample of 94 ultraluminous, optical quasars from the search of over 14,486 deg^2 by Onken et al. 2022 in the range 4.4<redshift<5.2 and match them against the Rapid ASKAP Continuum Survey (RACS) observed on the Australian Square Kilometre Array Pathfinder (ASKAP). From this most complete sample of the bright end of the redshift ~5 quasar luminosity function, there are 10 radio continuum detections of which 8 are considered radio-loud quasars. The radio-loud fraction for this sample is 8.5 \pm 2.9 per cent. Jiang et al. 2007 found that there is a decrease in the radio-loud fraction of quasars with increasing redshift and an increase with increasing absolute magnitude at rest frame 2500 Angstroms. We show that the radio-loud fraction of our quasar sample is consistent with that predicted by Jiang et al. 2007, extending their result to higher redshifts.Comment: Accepted by MNRA

    Pulmonary Dysfunction in Patients with Femoral Shaft Fracture Treated with Intramedullary Nailing

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    Background: This study was undertaken to determine whether alveolar dead space increases during intramedullary nailing of femoral shaft fractures and whether alveolar dead space predicts postoperative pulmonary dysfunction in patients undergoing intramedullary nailing of a femoral shaft fracture. Methods: All patients with a femoral shaft fracture were prospectively enrolled in the study unless there was evidence of acute myocardial infarction, shock, or heart failure. Arterial blood gases were measured at three consecutive time-periods after induction of general anesthesia: before intramedullary nailing and ten and thirty minutes after intramedullary nailing. The end-tidal carbon-dioxide level, minute ventilation, positive end‐expiratory pressure, and percent of inspired and expired inhalation agent were recorded simultaneously with the blood-gas measurement. Postoperatively, all subjects were monitored for evidence of pulmonary dysfunction, defined as the need for mechanical ventilation or supplemental oxygen (at a fraction of inspired oxygen of >40%) in the presence of clinical signs of a respiratory rate of >20 breaths/min or the use of accessory muscles of respiration. Results: Seventy‐four patients with a total of eighty femoral shaft fractures completed the study. Fifty fractures (62.5%) underwent nailing after reaming, and thirty fractures (37.5%) underwent nailing with minimal or no reaming. The mean alveolar dead-space measurements before canal opening and at ten and thirty minutes after canal opening were 14.5%, 15.8%, and 15.2% in the total series of seventy‐four patients (general linear model, p = 0.2) and 20.5%, 22.7%, and 24.2% in the twenty patients with postoperative pulmonary dysfunction (general linear model, p = 0.05). Of the twenty‐one patients with an alveolar dead-space measurement of >20% thirty minutes after nailing, sixteen had postoperative pulmonary dysfunction. According to univariate and multivariate analysis, the alveolar dead-space measurement was strongly associated with postoperative pulmonary dysfunction. Conclusions: According to our data, intramedullary nailing of femoral shaft fractures did not significantly increase alveolar dead space, and the amount of alveolar dead space can predict which patients will have pulmonary dysfunction postoperatively

    Path-integral analysis of fluctuation theorems for general Langevin processes

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    We examine classical, transient fluctuation theorems within the unifying framework of Langevin dynamics. We explicitly distinguish between the effects of non-conservative forces that violate detailed balance, and non-autonomous dynamics arising from the variation of an external parameter. When both these sources of nonequilibrium behavior are present, there naturally arise two distinct fluctuation theorems.Comment: 24 pages, one figur

    Electrospinning 3D bioactive glasses for wound healing

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    An electrospinning technique was used to produce three-dimensional (3D) bioactive glass fibrous scaffolds, in the SiO2-CaO system, for wound healing applications. Previously, it was thought that 3D cotton wool-like structures could only be produced when the sol contained calcium nitrate, implying that the Ca2+ and its electronic charge had a significant effect on the structure produced. Here, fibres with a 3D appearance were also electrospun from compositions containing only silica. A polymer binding agent was added to inorganic sol-gel solutions, enabling electrospinning prior to bioactive glass network formation and the polymer was removed by calcination. While the addition of Ca2+ contributes to the 3D morphology, here we show that other factors, such as relative humidity, play an important role in producing the 3D cotton-wool-like macrostructure of the fibres. A human dermal fibroblast cell line (CD-18CO) was exposed to dissolution products of the samples. Cell proliferation and metabolic activity tests were carried out and a VEGF ELISA showed a significant increase in VEGF production in cells exposed to the bioactive glass samples compared to control in DMEM. A novel SiO2-CaO nanofibrous scaffold was created that showed tailorable physical and dissolution properties, the control and composition of these release products are important for directing desirable wound healing interactions

    Calcineurin/NFAT Signaling in Activated Astrocytes Drives Network Hyperexcitability in A\u3cem\u3eβ\u3c/em\u3e-Bearing Mice

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    Hyperexcitable neuronal networks are mechanistically linked to the pathologic and clinical features of Alzheimer\u27s disease (AD). Astrocytes are a primary defense against hyperexcitability, but their functional phenotype during AD is poorly understood. Here, we found that activated astrocytes in the 5xFAD mouse model were strongly associated with proteolysis of the protein phosphatase calcineurin (CN) and the elevated expression of the CN-dependent transcription factor nuclear factor of activated T cells 4 (NFAT4). Intrahippocampal injections of adeno-associated virus vectors containing the astrocyte-specific promoter Gfa2 and the NFAT inhibitory peptide VIVIT reduced signs of glutamate-mediated hyperexcitability in 5xFAD mice, measured in vivo with microelectrode arrays and ex vivo brain slices, using whole-cell voltage clamp. VIVIT treatment in 5xFAD mice led to increased expression of the astrocytic glutamate transporter GLT-1 and to attenuated changes in dendrite morphology, synaptic strength, and NMDAR-dependent responses. The results reveal astrocytic CN/NFAT4 as a key pathologic mechanism for driving glutamate dysregulation and neuronal hyperactivity during AD

    Early-stage Fundraising of University Spin-offs: A Study through Demand-site Perspectives

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    University spin-offs have increasingly received attention from academia, governments and policy-makers. However, there are only a limited number of studies which fully understand the contribution made by the founding team to fundraising, specifically how they use their social networks and capabilities, especially within the university spin-off context. Employing a resource-based view theory and social networks approach, this paper examines whether a founding team exploits its social networks and capabilities to signal the value of a university spin-off. Capabilities are analysed through a set of constructs - technology, strategy, human capital, organizational viability and commercial resource - that have been derived from previous literature. The contribution made by social networks is evaluated using three dimensions - structure, governance and content - which form the construct of relationships within a network. Based on data from 181 university spin-offs in Spain, this paper empirically demonstrates that by exploiting social networks a founding team can improve its capabilities which, in turn, enhance its fundraising ability

    Hubble Space Telescope survey of the Perseus Cluster -IV: Compact stellar systems in the Perseus Cluster core and Ultra Compact Dwarf formation in star forming filaments

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    We present the results of the first search for Ultra Compact Dwarfs (UCDs) in the Perseus Cluster core, including the region of the cluster around the unusual Brightest Cluster Galaxy (BCG) NGC 1275. Utilising Hubble Space Telescope Advanced Camera for Surveys imaging, we identify a sample of 84 UCD candidates with half-light radii 10 pc < r_e < 57 pc out to a distance of 250 kpc from the cluster centre, covering a total survey area of ~70 armin^2. All UCDs in Perseus lie in the same size-luminosity locus seen for confirmed UCDs in other regions of the local Universe. The majority of UCDs are brighter than M_R = -10.5, and lie on an extrapolation of the red sequence followed by the Perseus Cluster dwarf elliptical population to fainter magnitudes. However, three UCD candidates in the vicinity of NGC 1275 are very blue, with colours (B-R)_0 < 0.6 implying a cessation of star formation within the past 100 Myr. Furthermore, large blue star clusters embedded in the star forming filaments are highly indicative that both proto-globular clusters (GCs) and proto-UCDs are actively forming at the present day in Perseus. We therefore suggest star forming filaments as a formation site for some UCDs, with searches necessary in other low redshift analogues of NGC 1275 necessary to test this hypothesis. We also suggest that tidal disruption of dwarf galaxies is another formation channel for UCD formation in the core of Perseus as tidal disruption is ongoing in this region as evidenced by shells around NGC 1275. Finally, UCDs may simply be massive GCs based on strong similarities in the colour trends of the two populations.Comment: 18 pages, 20 figures, 3 tables. Accepted for publication in MNRA

    Facilitator, Functionary, Friend or Foe? Studying the Role of iPads within Learning Activities Across a School Year

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    We present the findings from a longitudinal study of iPad use in a Primary school classroom. While tablet devices have found their way into classroom environments, we still lack in depth and long-term studies of how they integrate into everyday classroom activities. Our findings illustrate in-classroom tablet use and the broad range of learning activities in subjects such as maths, languages, social sciences, and even physical education. Our observations expand current models on teaching and learning supported by tablet technology. Our findings are child-centred, focusing on three different roles that tablets can play as part of learning activities: Friend, Functionary, and Facilitator. This new perspective on in-classroom tablet use can facilitate critical discussions around the integration and impact of these devices in the educational context, from a design and educational point of view
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