Utrecht University

Utrecht University Repository
Not a member yet
    182882 research outputs found

    Luminescence and Formation of Cubic and Hexagonal (K,Rb)2SiF6:Mn4+

    Full text link
    The efficient red-emitting phosphor K2SiF6:Mn4+ (KSF) is widely used for low-power LED applications. The saturated red color and sharp line emission are ideal for application in backlight LEDs for displays. However, the long excited state lifetime lowers the external quantum yield (EQY) at high photon flux, limiting the application in (higher power density) lighting. Here, we report the synthesis of a new crystalline phase: hexagonal (K,Rb)SiF6:Mn4+ (h-KRSF). Due to the lower local symmetry, the Mn4+ emission in this new host material shows a pronounced zero phonon line, which is different from Mn4+ in the cubic KSF. The lower symmetry reduces the excited state lifetime, and thus, the loss of EQY under high photon fluxes, and the spectral change also increases the lumen/W output. Temperature-dependent emission and lifetime measurements reveal a high luminescence quenching temperature of ∼500 K, similar to that of KSF. The formation mechanism of h-KRSF was studied in situ by measuring the emission spectra of the precipitate in solution over time. Initially, nanocrystalline cubic KRSF (c-KRSF) is formed, which transforms into a microcrystalline hexagonal precipitate with a surprising exponential increase in the transformation rate with time. The stability of the new phase was studied by temperature-dependent XRD, and an irreversible transition back to the cubic phase was seen upon heating to temperatures above 200 °C

    Practices of Transmission and Construction of a Sense of Belonging in Judeo-Latin American Women Writers: An Introduction

    Full text link
    Las entrevistas recopiladas en este dossier, complementan los estudios de la sección temática “Rutas de autoras judeo-latinoamericanas hacia un sentido de pertenencia”, incluidos en este mismo número de América sin Nombre. En esta sección temática, hemos explorado la representación de las trayectorias, los mapas y los lugares en la obra literaria de las autoras judeo-latinoamericanas. Entre las conclusiones de dicha sección temática, destaca la necesidad que sienten las autoras estudiadas de crear una identidad espacial a través de su obra literaria. Además, la creación de los lugares de origen y de la trayectoria de los ancestros en su obra literaria es un elemento constantemente presente. Las autoras escriben y reescriben esos lugares a lo largo de sus libros y parece como si estuvieran remodelando esos lugares reiteradamente sin que éstos lleguen a tener nunca una forma definitiva. Este rasgo recurrente de la obra literaria de las autoras judeo-latinoamericanas estudiadas hace surgir una serie de interrogantes: ¿Qué es lo que las autoras conocen sobre sus lugares de origen? ¿Cuál es la imagen que han recibido de éstos? ¿Cómo se realizó en sus familias la transmisión intergeneracional de la imagen del lugar de pertenencia? A fin de responder algunas de estas preguntas, en esta sección de entrevistas nos alejamos del nivel de la ficción para adentrarnos a la realidad de las familias de las autoras. Nos proponemos, así, explorar otra faceta en la construcción del sentido de pertenencia, mediante el registro de las diferentes modalidades de transmisión intergeneracional de los imaginarios espaciales en el exilio judeo-latinoamericano. Este dossier de entrevistas proporciona, así, un contrapunto a las conclusiones que hemos sacado de los estudios de la sección temática “Rutas de autoras judeo-latinoamericanas hacia un sentido de pertenencia”

    Political tolerance and the golden rule: Reciprocity increases acceptance of normative protest actions of disliked groups

    Full text link
    The golden rule is a widespread moral guide for preventing conflict across cultures and religions, and reciprocity is foundational to political tolerance. This raises the question of whether the golden rule has an impact on one's willingness to tolerate political protest actions of disliked ideological groups. In the current research, we examined whether making salient golden rule reciprocity impacts on political tolerance of one's least-liked groups. Data from two experiments (N = 950) revealed that participants who watched a 3-min video highlighting the golden rule showed significantly more tolerance of normative protest actions of their least-liked group relative to watching a control video. By contrast, the golden rule video had no significant impact on tolerance of non-normative protest actions of one's least-liked group. Additionally, the golden rule video had no impact on one's attitudes or willingness to engage in contact with the least-liked group indicating that increased political tolerance of normative protest actions was not due to changing attitudes towards the least-liked group. Collectively, these studies demonstrate that reminders of the principle of reciprocity and the golden rule can increase political tolerance with benefits for liberal democracy. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement

    Long-term exposure to several constituents and sources of PM 2.5 is associated with incidence of upper aerodigestive tract cancers but not gastric cancer: Results from the large pooled European cohort of the ELAPSE project.

    Full text link
    It is unclear whether cancers of the upper aerodigestive tract (UADT) and gastric cancer are related to air pollution, due to few studies with inconsistent results. The effects of particulate matter (PM) may vary across locations due to different source contributions and related PM compositions, and it is not clear which PM constituents/sources are most relevant from a consideration of overall mass concentration alone. We therefore investigated the association of UADT and gastric cancers with PM 2.5 elemental constituents and sources components indicative of different sources within a large multicentre population based epidemiological study. Cohorts with at least 10 cases per cohort led to ten and eight cohorts from five countries contributing to UADT- and gastric cancer analysis, respectively. Outcome ascertainment was based on cancer registry data or data of comparable quality. We assigned home address exposure to eight elemental constituents (Cu, Fe, K, Ni, S, Si, V and Zn) estimated from Europe-wide exposure models, and five source components identified by absolute principal component analysis (APCA). Cox regression models were run with age as time scale, stratified for sex and cohort and adjusted for relevant individual and neighbourhood level confounders. We observed 1139 UADT and 872 gastric cancer cases during a mean follow-up of 18.3 and 18.5 years, respectively. UADT cancer incidence was associated with all constituents except K in single element analyses. After adjustment for NO 2, only Ni and V remained associated with UADT. Residual oil combustion and traffic source components were associated with UADT cancer persisting in the multiple source model. No associations were found for any of the elements or source components and gastric cancer incidence. Our results indicate an association of several PM constituents indicative of different sources with UADT but not gastric cancer incidence with the most robust evidence for traffic and residual oil combustion

    Properties and performance of the one-parameter log-linear cognitive diagnosis model

    Full text link
    Diagnostic classification models (DCMs) are psychometric models that yield probabilistic classifications of respondents according to a set of discrete latent variables. The current study examines the recently introduced one-parameter log-linear cognitive diagnosis model (1-PLCDM), which has increased interpretability compared with general DCMs due to useful measurement properties like sum score sufficiency and invariance properties. We demonstrate its equivalence with the Latent Class/Rasch Model and discuss interpretational consequences. The model is further examined in a DCM framework. We demonstrate the sum score sufficiency property and we derive an expression for the cut score for mastery classification. It is shown by means of a simulation study that the 1-PLCDM is fairly robust to model constraint violations in terms of classification accuracy and reliability. This robustness in combination with useful measurementproperties and ease of interpretation can make the model attractive for stakeholders to apply in various assessment settings

    Introduction

    Full text link

    Peak-ring magnetism: Rock and mineral magnetic properties of the Chicxulub impact crater

    Full text link
    The Chicxulub impact event at ca. 66 Ma left in its wake the only complex crater on Earth with a preserved peak ring, characterized by a well-developed magnetic anomaly low. To date, little is known about its magnetic properties. The joint Integrated Ocean Drilling Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364 drill core M0077A revealed that the peak ring consists of uplifted and strongly deformed granitoid basement rocks overlain by a 130-m-thick impact melt and suevite layer. Pre- and postimpact hydrothermal systems affected this basement with maximum temperatures up to 450 °C. We used microscopy, mineral chemistry, temperature-dependent magnetic susceptibility, and hysteresis properties to characterize the magnetic mineralogy of pre-, syn-, and postimpact rocks. Compared to its amount of pure, stoichiometric shocked magnetite, the granitoid basement shows low magnetic susceptibility, which is in line with earlier experimental studies indicating that shock reduces magnetic susceptibility. Cation-substituted magnetite with varying compositions in the melt rocks carries a higher induced and remanent magnetization compared to the basement. In the granitoid basement, magnetite was partially oxidized to hematite by a pre-impact hydrothermal event, but at lithological contacts with high-temperature impact melt rock, this hematite was locally retransformed back to magnetite. Elsewhere in the granitoid basement, the temperature reached in the hydrothermal system was too low for hematite retransformation. It was also too low to anneal all the lattice defects in the shocked magnetite, which likely occurs above 540 °C. The presence of shocked magnetite in the granitoid basement well explains the magnetic anomaly low due to its unusually low induced magnetization

    Pembrolizumab Plus Chemotherapy Per PD-L1 Stratum In Patients With Metastatic Non-Small Cell Lung Cancer: Real-World Effectiveness Versus Trial Efficacy

    Full text link
    BACKGROUND: Clinical trial efficacy and real-world effectiveness of oncological treatments can differ. This study assessed the real-world survival outcomes of first-line pembrolizumab plus chemotherapy per PD-L1 stratum in patients with metastatic non-small cell lung cancer (mNSCLC) and compared them to clinical trial results. PATIENTS AND METHODS: All patients with nonsquamous and squamous mNSCLC who received first-line pembrolizumab plus chemotherapy in 7 Dutch teaching hospitals between January 1, 2019 and December 31, 2021 were included. Hazard ratios (HR) with confidence intervals (95% CI) for overall survival (OS) and progression-free survival (PFS) were estimated to determine the efficacy-effectiveness gap (EE gap) between real-world and clinical trial, stratified by PD-L1 stratum. RESULTS: The nonsquamous cohort (n = 486) consisted of 269 patients with PD-L1 1 in all other nonsquamous and squamous PD-L1 strata, although not statistically significant. No EE-gap for PFS was observed in any stratum. CONCLUSION: No significant EE gap was found for pembrolizumab plus chemotherapy, except in the stratum nonsquamous mNSCLC with <1% PD-L1 tumor expression. In these patients, the survival in real-world was considerably shorter compared to the clinical trial results. Further studies are needed to determine which patient, treatment and or context factors contribute to this disparity

    Single-molecule force stability of the SARS-CoV-2–ACE2 interface in variants-of-concern

    Full text link
    Mutations in SARS-CoV-2 have shown effective evasion of population immunity and increased affinity to the cellular receptor angiotensin-converting enzyme 2 (ACE2). However, in the dynamic environment of the respiratory tract, forces act on the binding partners, which raises the question of whether not only affinity but also force stability of the SARS-CoV-2–ACE2 interaction might be a selection factor for mutations. Using magnetic tweezers, we investigate the impact of amino acid substitutions in variants of concern (Alpha, Beta, Gamma and Delta) and on force-stability and bond kinetic of the receptor-binding domain–ACE2 interface at a single-molecule resolution. We find a higher affinity for all of the variants of concern (>fivefold) compared with the wild type. In contrast, Alpha is the only variant of concern that shows higher force stability (by 17%) compared with the wild type. Using molecular dynamics simulations, we rationalize the mechanistic molecular origins of this increase in force stability. Our study emphasizes the diversity of contributions to the transmissibility of variants and establishes force stability as one of the several factors for fitness. Understanding fitness advantages opens the possibility for the prediction of probable mutations, allowing a rapid adjustment of therapeutics, vaccines and intervention measures

    A citizen science toolkit to collect human perceptions of urban environments using open street view images

    Full text link
    Street View-level Imagery (SVI) is a valuable data source for studies (e.g., environmental assessments, green space identification or land cover classification). While commercial SVI is available, such providers commonly restrict copying or reuse in ways necessary for research. Open SVI datasets are readily available from less restrictive sources, such as Mapillary, but due to the heterogeneity of the images, these require substantial preprocessing, filtering, and careful quality checks. We present an efficient method for automated downloading, processing, cropping, and filtering open SVI, to be used in a survey of human perceptions of the streets portrayed in these images. We demonstrate our open-source reusable SVI preparation and smartphone-friendly perception-survey software with Amsterdam (Netherlands) as the case study. Using a citizen science approach, we collected from 331 people 22,637 ratings about their perceptions for various criteria. We have published our software in a public repository for future re-use and reproducibility

    44,467

    full texts

    182,882

    metadata records
    Updated in last 30 days.
    Utrecht University Repository is based in Netherlands
    Access Repository Dashboard
    Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇