1,194 research outputs found

    Cloud top entrainment instability and cloud top distributions

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    Classical cloud-top entrainment instability condition formulation is discussed. A saturation point diagram is used to investigate the details of mixing in cases where the cloud-top entrainment instability criterion is satisfied

    Haze in the Klang Valley of Malaysia

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    Continuous measurements of dry aerosol light scattering (Bsp) were made at two sites in the Klang Valley of Malaysia between December 1998 and December 2000. In addition 24-h PM2.5 samples were collected on a one-day-in-six cycle and the chemical composition of the aerosol was determined. Periods of excessive haze were defined as 24-h average Bsp values greater than 150 Mm-1 and these occurred on a number of occasions, between May and September 1999, during May 2000, and between July and September 2000. The evidence for smoke being a significant contributor to aerosol during periods of excessive haze is discussed and includes features of the aerosol chemistry, the diurnal cycle of Bsp, and the coincidence of forest fires on Sumatra during the southwest (SW) monsoon period, as well as transport modelling for one week of the southwest Monsoon of 2000. The study highlights that whilst transboundary smoke is a major contributor to poor visibility in the Klang Valley, smoke from fires on Peninsular Malaysia is also a contributor, and at all times, the domestic source of secondary particle production is present

    Bogoliubov speed of sound for a dilute Bose-Einstein condensate in a 3d optical lattice

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    We point out that the velocity of propagation of sound wavepackets in a Bose-Einstein condensate filling a three-dimensional cubic optical lattice undergoes a maximum with increasing lattice depth. For a realistic choice of parameters, the maximum sound velocity in a lattice condensate can exceed the sound velocity in a homogeneous condensate with the same average density by 30%. The maximum falls into the superfluid regime, and should be observable under currently achievable laboratory conditions

    Grootschalige landbouw in een kleinschalig landschap : oplossingsrichtingen voor toekomstgerichte grootschalige melkveehouderij uitgewerkt voor het kleinschalige, open veenweidelandschap van Laag Holland

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    Schaalvergroting wordt door de meeste veehouderijbedrijven gezien als een belangrijke mogelijkheid om de kostprijs te verlagen. Maar vooral in kleinschalige gebieden lopen grotere bedrijven tegen de grenzen van hun omgeving aan. Vanuit de maatschappij klinkt immers de roep om een mooier landschap en hogere natuurwaarden. In de brochure 'Grootschalige landbouw in een kleinschalig landschap' zijn oplossingsrichtingen voor toekomstgerichte grootschalige melkveehouderij uitgewerkt voor het kleinschalige, open veenweidelandschap van Laag Holland

    Hypermethylation of DNA Methylation Markers in Non-Cirrhotic Hepatocellular Carcinoma

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    Aberrant DNA methylation changes have been reported to be associated with carcinogenesis in cirrhotic HCC, but DNA methylation patterns for these non-cirrhotic HCC cases were not examined. Therefore, we sought to investigate DNA methylation changes on non-cirrhotic HCC using reported promising DNA methylation markers (DMMs), including HOXA1, CLEC11A, AK055957, and TSPYL5, on 146 liver tissues using quantitative methylation-specific PCR and methylated DNA sequencing. We observed a high frequency of aberrant methylation changes in the four DMMs through both techniques in non-cirrhotic HCC compared to cirrhosis, hepatitis, and benign lesions (p &lt; 0.05), suggesting that hypermethylation of these DMMs is specific to non-cirrhotic HCC development. Also, the combination of the four DMMs exhibited 78% sensitivity at 80% specificity with an AUC of 0.85 in discriminating non-cirrhotic HCC from hepatitis and benign lesions. In addition, HOXA1 showed a higher aberrant methylation percentage in non-cirrhotic HCC compared to cirrhotic HCC (43.3% versus 13.3%, p = 0.039), which was confirmed using multivariate linear regression (p &lt; 0.05). In summary, we identified aberrant hypermethylation changes in HOXA1, CLEC11A, AK055957, and TSPYL5 in non-cirrhotic HCC tissues compared to cirrhosis, hepatitis, and benign lesions, providing information that could be used as potentially detectable biomarkers for these unusual HCC cases in clinical practice.</p

    Recruitment and Retention of Older People in Clinical Research: A Systematic Literature Review

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    OBJECTIVE: To identify barriers and solutions for the recruitment and retention of older (aged ≥65 years) people in clinical trials. DESIGN: Systematic literature review. METHODS: Three databases (Medline, Embase, and CENTRAL) were searched for articles reporting on barriers or solutions regarding the recruitment or retention of older people. Only original research articles were included. RESULTS: Fifty eligible articles were identified. Exclusion criteria were the most common cause of poor recruitment of older adults (mainly age and comorbidities). Patients' families or physicians often advised against participation (22% of included studies). Lack of interest (18%) and problems with transportation (18%) were also commonly cited as challenges. Fourteen trials (28%) reported that monitoring and adapting their recruitment methods helped, along with a flexible research team (26%) and provision of transportation (24%). Retention was impaired by death (12%), illness (8%), and loss of interest (6%). Methods with a positive effect on retention included financial incentives and regular information about the progress of the study (12%), a low staff turnover (12%), flexibility in appointment making (10%), and expression of appreciation by the staff through letters, gifts, and cards to the participants (10%). CONCLUSION: We identified several barriers and have listed potential solutions that may improve recruitment and lead to fewer dropouts in trials involving older populations. Implementation of our findings may help mitigate the manifold challenges that come with running a trial with older people

    Bragg spectroscopy of a superfluid Bose-Hubbard gas

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    Bragg spectroscopy is used to measure excitations of a trapped, quantum-degenerate gas of 87Rb atoms in a 3-dimensional optical lattice. The measurements are carried out over a range of optical lattice depths in the superfluid phase of the Bose-Hubbard model. For fixed wavevector, the resonant frequency of the excitation is found to decrease with increasing lattice depth. A numerical calculation of the resonant frequencies based on Bogoliubov theory shows a less steep rate of decrease than the measurements.Comment: 11 pages, 4 figure

    Covid-19 and maternal and perinatal outcomes

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    Background: Alveolar capillary dysplasia with or without misalignment of the pulmonary veins (ACD/MPV) is a lethal congenital lung disorder associated with a variety of heterozygous genomic alterations in the FOXF1 gene or its 60 kb enhancer. Cases without a genomic alteration in the FOXF1 locus have been described as well. The mechanisms responsible for FOXF1 haploinsufficiency and the cause of ACD/MPV in patients without a genomic FOXF1 variant are poorly understood, complicating the search for potential therapeutic targets for ACD/MPV. To investigate the contribution of aberrant DNA methylation, genome wide methylation patterns of ACD/MPV lung tissues were compared with methylation patterns of control lung tissues using the recently developed technique Methylated DNA sequencing (MeD-seq). Results: Eight ACD/MPV lung tissue samples and three control samples were sequenced and their mutual comparison resulted in identification of 319 differentially methylated regions (DMRs) genome wide, involving 115 protein coding genes. The potentially upregulated genes were significantly enriched in developmental signalling pathways, whereas potentially downregulated genes were mainly enriched in O-linked glycosylation. In patients with a large maternal deletion encompassing the 60 kb FOXF1 enhancer, DNA methylation patterns in this FOXF1 enhancer were not significantly different compared to controls. However, two hypermethylated regions were detected in the 60 kb FOXF1 enhancer of patients harbouring a FOXF1 point mutation. Lastly, a large hypermethylated region overlapping the first FOXF1 exon was found in one of the ACD/MPV patients without a known pathogenic FOXF1 variation. Conclusion: This is the first study providing genome wide methylation data on lung tissue of ACD/MPV patients. DNA methylation analyses in the FOXF1 locus excludes maternal imprinting of the 60 kb FOXF1 enhancer. Hypermethylation at the 60 kb FOXF1 enhancer might contribute to FOXF1 haploinsufficiency caused by heterozygous mutations in the FOXF1 coding region. Interestingly, DNA methylation analyses of patients without a genomic FOXF1 variant suggest that abnormal hypermethylation of exon 1 might play a role in some ACD/MPV in patients.</p

    Решение задач многокритериальной оптимизации с использованием генетических алгоритмов

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    В данной работе представлены существующие подходы и методы применения генетических алгоритмов для решения задач многокритериальной оптимизации. Предложены математическая модель и алгоритмы решения многокритериальной задачи выбора стратегии развития производственной системы. Представлены также результаты применения для решения этой задачи метода присваивания рангов Голдберга и гибридного генетического алгоритма.Представлені існуючи підходи і методи застосування генетичних алгоритмів для рішення залач багатокритеріальної оптимізації. Запропоновано математичну модель і алгоритми розв’язку багатокритеріальної задачі вибору стратегії розвитку виробничої системи. Навелено результати застосування для розв’язку цієї задачі методу надання рангів Голдберга і гібридного генетичного алгоритму.This paper describes the existing approaches and methods of application of genetic algorithms for multiobjective optimization. The mathematical model and algorithms for solving multiobjective optimization problems in management have been proposed. Experimental results of application of the hybrid genetic algorithms for solving combinatorial optimization problems have been presented

    PROMIS Physical Function short forms display item- and scale-level characteristics at least as good as the Roland Morris Disability Questionnaire in patients with chronic low back pain

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    OBJECTIVE: To compare dimensionality, item-level characteristics, scale-level reliability and construct validity of PROMIS® Physical Function short forms (PROMIS-PF) and 24-item Roland Morris Disability Questionnaire (RMDQ-24) in patients with chronic low back pain (LBP). DESIGN: Cross-sectional study. SETTING: Secondary care center for rehabilitation and rheumatology. PARTICIPANTS: Patients with non-specific LBP ≥ 3 months (n = 768). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Dutch versions of the 4-, 6-, 8-, 10- and 20-item PROMIS-PF, and of the RMDQ-24. RESULTS: Mean age was 49 years (±13), 77% female, 54% displayed pain for more than 5 years. PROMIS-PF-6, PROMIS-PF-8 and RMDQ-24 exhibited sufficient unidimensionality (confirmatory factor analysis: CFI >0.950, TLI >0.950 and RMSEA 0.001). Two-parameter item response theory models found two items with low discrimination for RMDQ-24. All other instruments had adequate fit statistics and item parameters. PROMIS-PF-20 displayed the best scale-level reliability. Construct validity was sufficient for all instruments as all hypotheses on expected correlations with other instruments, and differences between relevant subgroups, were met. CONCLUSIONS: PROMIS-PF-6, PROMIS-PF-8 and RMDQ-24 exhibited better unidimensionality, whereas PROMIS-PF-4, PROMIS-PF-6 PROMIS-PF-8 and PROMIS-PF-10 showed superior item-level characteristics. PROMIS-PF-20 was the instrument with the best scale-level reliability. This study warrants assessment of other measurement properties of PROMIS-PF short forms in comparison to disease-specific physical functioning instruments in LBP
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