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- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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- Bozkurt, M., et al.
(författare)
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Magnetic anisotropy of single Mn acceptors in GaAs in an external magnetic field
- 2013
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical society. - 1098-0121 .- 1550-235X. ; 88, s. Article ID: 205203-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of an external magnetic field on the physical properties of the acceptor hole statesassociated with single Mn acceptors placed near the (110) surface of GaAs. Cross-sectional scanning tunnelingmicroscopy images of the acceptor local density of states (LDOS) show that the strongly anisotropic hole wavefunction is not significantly affected by a magnetic field up to 6 T. These experimental results are supported bytheoretical calculations based on a tight-binding model of Mn acceptors in GaAs. For Mn acceptors on the (110)surface and the subsurfaces immediately underneath, we find that an applied magnetic field modifies significantlythe magnetic anisotropy landscape. However, the acceptor hole wave function is strongly localized around theMn and the LDOS is quite independent of the direction of the Mn magnetic moment. On the other hand, for Mnacceptors placed on deeper layers below the surface, the acceptor hole wave function is more delocalized andthe corresponding LDOS is much more sensitive on the direction of the Mn magnetic moment. However, themagnetic anisotropy energy for these magnetic impurities is large (up to 15 meV), and a magnetic field of 10 Tcan hardly change the landscape and rotate the direction of the Mn magnetic moment away from its easy axis.We predict that substantially larger magnetic fields are required to observe a significant field dependence of thetunneling current for impurities located several layers below the GaAs surface.
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- d’Alessandro, N., et al.
(författare)
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RAMCESS 2.x FRAMEWORK - EXPRESSIVE VOICE ANALYSIS FOR REALTIME AND ACCURATE SYNTHESIS OF SINGING
- 2008
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Ingår i: Journal on Multimodal User Interfaces. - : Springer. - 1783-7677 .- 1783-8738. ; 2, s. 133-144
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present the work that has been achieved in the context of the second version of the RAMCESS singing synthesis framework. The main improvement of this study is the integration of new algorithms for expressive voice analysis, especially the separation of the glottal source and the vocal tract. Realtime synthesis modules have also been refined. These elements have been integrated in an existing digital instrument: the HANDSKETCH 1.X, a bimanual controller. Moreover this digital instrument is compared to existing systems.
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| 17. |
- Networked Learning Editorial Collective, (NLEC), et al.
(författare)
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Networked Learning in 2021: A Community Definition
- 2021
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Ingår i: Postdigital Science and Education. - : Springer. - 2524-4868 .- 2524-485X. ; 3, s. 326-369
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Tidskriftsartikel (refereegranskat)abstract
- Introduction (Networked Learning Editorial Collective): Since the turn of this century, much of the world has undergone a tectonic socio-technological change. Computers have left the isolated basements of research institutes and entered people's homes. Network connectivity has advanced from slow and unreliable modems to high-speed broadband. Devices have evolved: from stationary desktop computers to ever-present, always-connected smartphones. These developments have been accompanied by new digital practices, and changing expectations, not least in education, where enthusiasm for digital technologies has been kindled by quite contrasting sets of values. For example, some critical pedagogues working in the traditions of Freire and Illich have understood computers as novel tools for political and social emancipation, while opportunistic managers in cash-strapped universities have seen new opportunities for saving money and/or growing revenues. Irrespective of their ideological leanings, many of the early attempts at marrying technology and education had some features in common: instrumentalist understanding of human relationships with technologies, with a strong emphasis on practice and 'what works'.It is now clear that, in many countries, managerialist approaches have provided the framing, while local constraints and exigencies have shaped operational details, in fields such as e-learning, Technology Enhanced Learning, and others waving the 'Digital' banner. Too many emancipatory educational movements have ignored technology, burying their heads in the sand, or have wished it away, subscribing toa new form of Luddism, even as they sense themselves moving to the margins. But this situation is not set in stone. Our postdigital reality results from a complex interplay between centres and margins. Furthermore, the concepts of centres and margins 'have morphed into formations that we do not yet understand, and they have created (power) relationships which are still unsettled. The concepts … have not disappeared, but they have become somewhat marginal in their own right.' (Jandrić andHayes 2019) Social justice and emancipation are as important as ever, yet they require new theoretical reconfigurations and practices fit for our socio-technological moment.In the 1990s, networked learning (NL) emerged as a critical response to dominant discourses of the day. NL went against the grain in two main ways. First, it embarked on developing nuanced understandings of relationships between humans and technologies; understandings which reach beyond instrumentalism and various forms of determinism. Second, NL embraced the emancipatory agenda of the critical pedagogy movement and has, in various ways, politically committed to social justice (Beaty et al. 2002; Networked Learning Editorial Collective 2020). Gathered around the biennial Networked Learning Conference,1 the Research in NetworkedLearning book series,2 and a series of related projects and activities, the NL community has left a significant trace in educational transformations over the last few decades.Twenty years ago, founding members of the NL community offered a definition of NL which has strongly influenced the NL community’s theoretical perspectives and research approaches (Goodyear et al. 2004).3 Since then, however, the world has radically changed. With this in mind, the Networked Learning Editorial Collective (NLEC) recently published a paper entitled 'Networked Learning: InvitingRedefinition' (2020). In line with NL's critical agenda, a core goal for the paper was to open up a broad discussion about the current meaning and understandings of NL and directions for its further development.The current collectively authored paper presents the responses to the NLEC's open call. With 40 contributors coming from six continents and working across many fields of education, the paper reflects the breadth and depth of current understandings of NL. The responses have been collated, classified into main themes, and lightly edited for clarity. One of the responders, Sarah Hayes, was asked to write aconclusion. The final draft paper has undergone double open review. The reviewers, Laura Czerniewicz and Jeremy Knox, are acknowledged as authors.Our intention, in taking this approach, has been to further stimulate democratic discussion about NL and to prompt some much-needed community-building.
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| 18. |
- Ovadia, C., et al.
(författare)
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Association of adverse perinatal outcomes of intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and individual patient data meta-analyses
- 2019
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Ingår i: The Lancet. - : Elsevier BV. - 0140-6736. ; 393:10174, s. 899-909
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Tidskriftsartikel (refereegranskat)abstract
- Background Intrahepatic cholestasis of pregnancy is associated with adverse perinatal outcomes, but the association with the concentration of specific biochemical markers is unclear. We aimed to quantify the adverse perinatal effects of intrahepatic cholestasis of pregnancy in women with increased serum bile acid concentrations and determine whether elevated bile acid concentrations were associated with the risk of stillbirth and preterm birth. Methods We did a systematic review by searching PubMed, Web of Science, and Embase databases for studies published from database inception to June 1, 2018, reporting perinatal outcomes for women with intrahepatic cholestasis of pregnancy when serum bile acid concentrations were available. Inclusion criteria were studies defining intrahepatic cholestasis of pregnancy based upon pruritus and elevated serum bile acid concentrations, with or without raised liver aminotransferase concentrations. Eligible studies were case-control, cohort, and population-based studies, and randomised controlled trials, with at least 30 participants, and that reported bile acid concentrations and perinatal outcomes. Studies at potential higher risk of reporter bias were excluded, including case reports, studies not comprising cohorts, or successive cases seen in a unit; we also excluded studies with high risk of bias from groups selected (eg, a subgroup of babies with poor outcomes were explicitly excluded), conference abstracts, and Letters to the Editor without clear peer review. We also included unpublished data from two UK hospitals. We did a random effects meta-analysis to determine risk of adverse perinatal outcomes. Aggregate data for maternal and perinatal outcomes were extracted from case-control studies, and individual patient data (IPD) were requested from study authors for all types of study (as no control group was required for the IPD analysis) to assess associations between biochemical markers and adverse outcomes using logistic and stepwise logistic regression. This study is registered with PROSPERO, number CRD42017069134. Findings We assessed 109 full-text articles, of which 23 studies were eligible for the aggregate data meta-analysis (5557 intrahepatic cholestasis of pregnancy cases and 165 136 controls), and 27 provided IPD (5269 intrahepatic cholestasis of pregnancy cases). Stillbirth occurred in 45 (0.83%) of 4936 intrahepatic cholestasis of pregnancy cases and 519 (0.32%) of 163 947 control pregnancies (odds ratio [OR] 1.46 [95% CI 0.73-2.89]; I-2 = 59.8%). In singleton pregnancies, stillbirth was associated with maximum total bile acid concentration (area under the receiver operating characteristic curve [ROC AUC]) 0.83 [95% CI 0.74-0.92]), but not alanine aminotransferase (ROC AUC 0.46 [0.35-0.57]). For singleton pregnancies, the prevalence of stillbirth was three (0.13%; 95% CI 0.02-0.38) of 2310 intrahepatic cholestasis of pregnancy cases in women with serum total bile acids of less than 40 mu mol/L versus four (0.28%; 0.08-0.72) of 1412 cases with total bile acids of 40-99 mu mol/L (hazard ratio [HR] 2.35 [95% CI 0.52-10.50]; p=0.26), and versus 18 (3.44%; 2.05-5.37) of 524 cases for bile acids of 100 mu mol/L or more (HR 30.50 [8.83-105.30]; p<0.0001). Interpretation The risk of stillbirth is increased in women with intrahepatic cholestasis of pregnancy and singleton pregnancies when serum bile acids concentrations are of 100 mu mol/L or more. Because most women with intrahepatic cholestasis of pregnancy have bile acids below this concentration, they can probably be reassured that the risk of stillbirth is similar to that of pregnant women in the general population, provided repeat bile acid testing is done until delivery. Funding Tommy's, ICP Support, UK National Institute of Health Research, Wellcome Trust, and Genesis Research Trust. Copyright (c) 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.
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| 19. |
- Sneden, Christopher, et al.
(författare)
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Chemical Compositions of Red Giant Stars from Habitable Zone Planet Finder Spectroscopy
- 2021
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 161:3
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Tidskriftsartikel (refereegranskat)abstract
- We have used the Habitable Zone Planet Finder (HPF) to gather high-resolution, high signal-to-noise near-infrared spectra of 13 field red horizontal branch (RHB) stars, one open cluster giant, and one very metal-poor halo red giant. The HPF spectra cover the 0.81-1.28 mu m wavelength range of the zyJ bands, partially filling the gap between the optical (0.4-1.0 mu m) and infrared (1.5-2.4 mu m) spectra already available for the program stars. We derive abundances of 17 species from LTE-based computations involving equivalent widths and spectrum syntheses, and estimate abundance corrections for the species that are most affected by departures from LTE in RHB stars. Generally good agreement is found between HPF-based metallicities and abundance ratios and those from the optical and infrared spectral regions. Light element transitions dominate the HPF spectra of these red giants, and HPF data can be used to derive abundances from species with poor or no representation in optical spectra (e.g., C i, P i, S i, K i). Attention is drawn to the HPF abundances in two field solar-metallicity RHB stars of special interest: one with an extreme carbon isotope ratio, and one with a rare, very large lithium content. The latter star is unique in our sample in exhibiting very strong He i 10830 A absorption. The abundances of the open cluster giant concur with those derived from other wavelength regions. Detections of C i and S i in HD 122563 are reported, yielding the lowest metallicity determination of [S/Fe] from more than one multiplet.
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| 20. |
- Sneden, Christopher, et al.
(författare)
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The Active Chromospheres of Lithium-rich Red Giant Stars
- 2022
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 940:1
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Tidskriftsartikel (refereegranskat)abstract
- We have gathered near-infrared zyJ-band high-resolution spectra of nearly 300 field red giant stars with known lithium abundances in order to survey their He i λ10830 absorption strengths. This transition is an indicator of chromospheric activity and/or mass loss in red giants. The majority of stars in our sample reside in the red clump or red horizontal branch based on their V − J, MV color–magnitude diagram, and Gaia Teff and log(g) values. Most of our target stars are Li-poor in the sense of having normally low Li abundances, defined here as log ò(Li) < 1.25. Over 90% of these Li-poor stars have weak λ10830 features. However, more than half of the 83 Li-rich stars (log ò(Li) > 1.25) have strong λ10830 absorptions. These large λ10830 lines signal excess chromospheric activity in Li-rich stars; there is almost no indication of significant mass loss. The Li-rich giants may also have a higher binary fraction than Li-poor stars, based on their astrometric data. It appears likely that both residence on the horizontal branch and present or past binary interaction play roles in the significant Li–He connection established in this survey.
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