262 research outputs found

    Friction in Forming of UD Composites

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    Effect of oxygen on the expression of hypoxia-inducible factors in human fetal lung explants

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    Background: Fetal lung development requires proper coordination between lung epithelial and vascular morphogenesis. A major determinant in lung vascular development is vascular endothelial growth factor (VEGF), which is regulated by hypoxia-inducible factors (HIFs). VEGF is expressed in the airway epithelium, while its receptors (VEGFRs) are expressed in the pulmonary mesenchyme. The hypoxic environment in utero is beneficial for fetal organogenesis, especially vascular development. However, little is known about the expression of HIFs and VEGFR-2 in the human fetal lung in vitro. Objectives: The purpose of this study was to investigate the effects of hypoxia on fetal lung morphology and mRNA expression of VEGF, VEGFR-2, HIF-2α, and HIF-3α. Methods: An explant culture technique was used to study the effects of normoxic and hypoxic conditions on human fetal lung. Results: The morphology remained largely unchanged in explants cultured under hypoxic or normoxic conditions. Quantitative RT-PCR showed that the mRNA expression of VEGF-A, but not VEGFR-2 is upregulated in explants cultured at 1.5% compared with 21% oxygen. We observed a nonsignificant increase in HIF-2α and HIF-3α mRNA expression in explants cultured at 1.5% oxygen. These data suggest that the mRNA expression of VEGF, and possibly HIF-2α and HIF-3α, is regulated by hypoxia in the developing human lung. Conclusion: This lung explant culture model appears to be a valuable model to unravel the molecular mechanisms of human lung development

    A phenomenology and epistemology of large language models: transparency, trust, and trustworthiness

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    This paper analyses the phenomenology and epistemology of chatbots such as ChatGPT and Bard. The computational architecture underpinning these chatbots are large language models (LLMs), which are generative artificial intelligence (AI) systems trained on a massive dataset of text extracted from the Web. We conceptualise these LLMs as multifunctional computational cognitive artifacts, used for various cognitive tasks such as translating, summarizing, answering questions, information-seeking, and much more. Phenomenologically, LLMs can be experienced as a “quasi-other”; when that happens, users anthropomorphise them. For most users, current LLMs are black boxes, i.e., for the most part, they lack data transparency and algorithmic transparency. They can, however, be phenomenologically and informationally transparent, in which case there is an interactional flow. Anthropomorphising and interactional flow can, in some users, create an attitude of (unwarranted) trust towards the output LLMs generate. We conclude this paper by drawing on the epistemology of trust and testimony to examine the epistemic implications of these dimensions. Whilst LLMs generally generate accurate responses, we observe two epistemic pitfalls. Ideally, users should be able to match the level of trust that they place in LLMs to the degree that LLMs are trustworthy. However, both their data and algorithmic opacity and their phenomenological and informational transparency can make it difficult for users to calibrate their trust correctly. The effects of these limitations are twofold: users may adopt unwarranted attitudes of trust towards the outputs of LLMs (which is particularly problematic when LLMs hallucinate), and the trustworthiness of LLMs may be undermined

    Uptake and effectiveness of a tailor-made online lifestyle programme targeting modifiable risk factors for dementia among middle-aged descendants of people with recently diagnosed dementia:study protocol of a cluster randomised controlled trial (Demin study)

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    INTRODUCTION: Descendants of patients with dementia have a higher risk to develop dementia. This study aims to investigate the uptake and effectiveness of an online tailor-made lifestyle programme for dementia risk reduction (DRR) among middle-aged descendants of people with recently diagnosed late-onset dementia. METHODS AND ANALYSIS: Demin is a cluster randomised controlled trial, aiming to include 21 memory clinics of which 13 will be randomly allocated to the passive (poster and flyer in a waiting room) and 8 to the active recruitment strategy (additional personal invitation by members of the team of the memory clinic). We aim to recruit 378 participants (40-60 years) with a parent who is recently diagnosed with Alzheimer's disease or vascular dementia at one of the participating memory clinics. All participants receive a dementia risk assessment (online questionnaire, physical examination and blood sample) and subsequently an online tailor-made lifestyle advice regarding protective (Mediterranean diet, low/moderate alcohol consumption and high cognitive activity) and risk factors (physical inactivity, smoking, loneliness, cardiovascular diseases (CVD), hypertension, high cholesterol, diabetes, obesity, renal dysfunction and depression) for dementia. The primary outcome is the difference in uptake between the two recruitment strategies. Secondary outcomes are change(s) in (1) the Lifestyle for Brain Health score, (2) individual health behaviours, (3) health beliefs and attitudes towards DRR and (4) compliance to the tailor-made lifestyle advice. Outcomes will be measured at 3, 6, 9 and 12 months after baseline. The effectiveness of this online tailor-made lifestyle programme will be evaluated by comparing Demin participants to a matched control group (lifelines cohort). ETHICS AND DISSEMINATION: This study has been approved by the Dutch Ministry of Health, Welfare and Sport according to the Population Screening Act. All participants have to give online informed consent using SMS-tan (transaction authentication number delivered via text message). Findings will be disseminated through peer-reviewed journals and (inter)national conferences. TRIAL REGISTRATION NUMBER: NTR7434

    Cognitive Behavioral Therapy for Antenatal Depression in a Pilot Randomized Controlled Trial and Effects on Neurobiological, Behavioral and Cognitive Outcomes in Offspring 3-7 Years Postpartum:A Perspective Article on Study Findings, Limitations and Future Aims

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    Purpose of Article: In a previous pilot randomized controlled trial including 54 pregnant women with depression, maternal mood improved after Cognitive Behavioural Therapy (CBT) compared to treatment as usual (TAU), showing medium to large effect sizes. The effect persisted up to 9 months postpartum, with infant outcomes also showing medium to large effects favoring CBT in various child domains. This perspective article summarizes the results of a follow-up that was performed approximately 5 years later in the same cohort, assessing the effects of antenatal Cognitive Behavioural Therapy for depression and anxiety on child buccal cell DNA-methylation, brain morphology, behavior and cognition. Findings: Children from the CBT group had overall lower DNA-methylation compared to children from the TAU group. Mean DNA-methylation of all NR3C1 promoter-associated probes did not differ significantly between the CBT and TAU groups. Children from the CBT group had a thicker right lateral occipital cortex and lingual gyrus. In the CBT group, Voxel-Based-Morphometry analysis identified one cluster showing increased gray matter concentration in the right medial temporal lobe, and fixel-based analysis revealed reduced fiber-bundle-cross-section in the Fornix, the Optical Tract, and the Stria Terminalis. No differences were observed in full-scale IQ or Total Problems Score. When the total of hypotheses tests in this study was considered, differences in DNA-methylation and brain measurements were no longer significant. Summary: Our explorative findings suggest that antenatal depression treatment decreases overall child DNA-methylation, increases cortical thickness, and decreases white matter fiber-bundle cross-section in regions involved in cognitive function and the stress response. Nevertheless, larger studies are warranted to confirm our preliminary conclusion that CBT in pregnancy alters neurobiological outcomes in children. Clinical relevance remains unclear as we found no effects of antenatal CBT on child behavior or cognition (yet)

    Quantifying methane vibrational and rotational temperature with Raman scattering

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    This work describes the theoretical basis and implementation of the measurement of vibrational (T vib) and rotational (T rot) temperatures in CH4 by fitting spontaneous Raman scattering spectra in the Pentad region. This method could be applied for thermal equilibrium temperature measurements applications, e.g. in combustion, or vibrational-rotational non-equilibrium applications, such as in plasma chemistry. The method of calculating these temperatures is validated against known temperature thermal equilibrium spectra up to 860 K from published data, giving an estimated relative error of 10%. This demonstrates that both the calculated stick spectrum and the algorithm to determine T vib and T rot for CH4 is robust to 860 K, but we expect it is valid to 1500 K. Additionally, a number of non-equilibrium spectra generated with a pulsed microwave plasma are fitted to find T vib and T rot, further demonstrating the applicability of this method in fitting non-equilibrium spectra.</p

    Evidence for a role of p38 kinase in hypoxia-inducible factor 1-independent induction of vascular endothelial growth factor expression by sodium arsenite.

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    Recently we have demonstrated that sodium arsenite induces the expression of hypoxia-inducible factor 1alpha (HIF-1alpha) protein and vascular endothelial growth factor (VEGF) in OVCAR-3 human ovarian cancer cells. We now show that arsenic trioxide, an experimental anticancer drug, exerts the same effects. The involvement of phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK) pathways in the effects of sodium arsenite was investigated. By using kinase inhibitors in OVCAR-3 cells, both effects of sodium arsenite were found to be independent of phosphatidylinositol 3-kinase and p44/p42 MAPKS but were attenuated by inhibition of p38 MAPK. A role for p38 in the regulation of HIF-1alpha and VEGF expression was supported further by analysis of activation kinetics. Experiments in mouse fibroblast cell lines, lacking expression of c-Jun N-terminal kinases 1 and 2, suggested that these kinases are not required for induction of HIF-1alpha protein and VEGF mRNA. Unexpectedly, sodium arsenite did not activate a HIF-1-dependent reporter gene in OVCAR-3 cells, indicating that functional HIF-1 was not induced. In agreement with this hypothesis, up-regulation of VEGF mRNA was not reduced in HIF-1alpha(-/-) mouse fibroblast cell lines. Altogether, these data suggest that not HIF-1, but rather p38, mediates induction of VEGF mRNA expression by sodium arsenite
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