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704 result(s) for "Simonsen, J."
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Liquid crystals of neat boron nitride nanotubes and their assembly into ordered macroscopic materials
Boron nitride nanotubes (BNNTs) have attracted attention for their predicted extraordinary properties; yet, challenges in synthesis and processing have stifled progress on macroscopic materials. Recent advances have led to the production of highly pure BNNTs. Here we report that neat BNNTs dissolve in chlorosulfonic acid (CSA) and form birefringent liquid crystal domains at concentrations above 170 ppmw. These tactoidal domains merge into millimeter- sized regions upon light sonication in capillaries. Cryogenic electron microscopy directly shows nematic alignment of BNNTs in solution. BNNT liquid crystals can be processed into aligned films and extruded into neat BNNT fibers. This study of nematic liquid crystals of BNNTs demonstrates their ability to form macroscopic materials to be used in high- performance applications.
Natural history museum collection and citizen science data show advancing phenology of Danish hoverflies (Insecta: Diptera, Syrphidae) with increasing annual temperature
We explore the phenological response by Danish hoverflies (Syrphidae) to continually rising annual temperatures by analysing >50.000 natural history collection and citizen science records for 37 species collected between 1900 and 2018, a period during which the annual average temperature in Denmark rose significantly (p << 0.01). We perform a simple linear regression analysis of the 10th percentile observation date for each species against year of observation. Fourteen of the species showed a statistically significant (p < 0.05) negative correlation between 10th percentile date and year of observation, indicating earlier emergence as a likely response to climatic warming. Eighteen species showed a non-significant (p ≥ 0.05) negative correlation between 10th percentile date and year of observation, while four species showed a non-significant (p ≥ 0.05) positive correlation, and one showed neither a positive nor a negative correlation. We explore the possible impact of the length of the data series on the regression analysis by dividing the species into four groups depending on how far back in time we have data: ultra-short series (with data from 2003-2018); short series (data from 1998-2018); medium series (data from 1980-2018); long series (data from 2018 to before 1980). The length of the series seems to have an effect on the results as 60% of the long series species (nine out of 15) showed a statistically significant negative correlation, while for the shorter series species less than 35% showed a statistically significant negative correlation. When we reduced the long series in length to short series, the proportion of statistically significant negative correlations fell to 33%, confirming this assumption. We conclude that northern temperate hoverflies generally react to the ongoing climatic warming by emerging earlier.
Review: current international research into cellulose nanofibres and nanocomposites
This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments in the area, with particular emphasis on applications. The types of cellulose nanofibres covered are those extracted from plants by acid hydrolysis (nanowhiskers), mechanical treatment and those that occur naturally (tunicate nanowhiskers) or under culturing conditions (bacterial cellulose nanofibrils). Research highlighted in the article are the use of cellulose nanowhiskers for shape memory nanocomposites, analysis of the interfacial properties of cellulose nanowhisker and nanofibril-based composites using Raman spectroscopy, switchable interfaces that mimic sea cucumbers, polymerisation from the surface of cellulose nanowhiskers by atom transfer radical polymerisation and ring opening polymerisation, and methods to analyse the dispersion of nanowhiskers. The applications and new advances covered in this review are the use of cellulose nanofibres to reinforce adhesives, to make optically transparent paper for electronic displays, to create DNA-hybrid materials, to generate hierarchical composites and for use in foams, aerogels and starch nanocomposites and the use of all-cellulose nanocomposites for enhanced coupling between matrix and fibre. A comprehensive coverage of the literature is given and some suggestions on where the field is likely to advance in the future are discussed.
Insights from DCE-MRI: blood–brain barrier permeability in the context of MS relapses and methylprednisolone treatment
Detecting multiple sclerosis (MS) relapses remains challenging due to symptom variability and confounding factors, such as flare-ups and infections. Methylprednisolone (MP) is used for severe relapses, decreasing the number of contrast-enhancing lesions on MRI. The influx constant (K ) derived from dynamic contrast-enhanced MRI (DCE-MRI), a marker of blood-brain barrier (BBB) permeability, has shown promise as a predictor of disease activity in relapsing-remitting MS (RRMS). To investigate the predictive value of K in relation to clinical MS relapses and MP treatment, comparing its performance with traditional MRI markers. We studied 20 RRMS subjects admitted for possible relapse, using DCE-MRI on admission to assess K in normal-appearing white matter (NAWM) via the Patlak model. Mixed-effects modeling compared the predictive accuracy of K , the presence of contrast-enhancing lesions (CEL), evidence of brain lesions (EBL; defined as the presence of CEL or new T2 lesions), and MP treatment on clinical relapse events. Five models were evaluated, including combinations of K , CEL, EBL, and MP, to determine the most robust predictors of clinical relapse. Model performance was assessed using accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), with bootstrapped confidence intervals. Superior predictive accuracy was demonstrated with the inclusion of EBL and K , alongside MP treatment (AIC = 66.12,  = 0.006), outperforming other models with a classification accuracy of 83% (CI: 73-92%), sensitivity of 78% (CI: 60-94%), and specificity of 86% (CI: 74-97%). This model showed the highest combined PPV (78%, CI: 60-94%) and NPV (86%, CI: 74-98%) compared to models with EBL or CEL alone, suggesting an added value of K in enhancing predictive reliability. These results support the use of K alongside conventional MRI imaging metrics, to improve clinical relapse prediction in RRMS. The findings underscore the utility of K as a marker of MS-related neuroinflammation, with potential for integration into relapse monitoring protocols. Further validation in larger cohorts is recommended to confirm the model's generalizability and clinical application.
The Grasshopper Paradigm in damselflies: evidence for phalanx-like postglacial recolonization of Europe from a Balkan refugium in Platycnemis pennipes Pallas (Odonata: Zygoptera: Platycnemidae)
We explore haplotype diversity, phylogeography and phylogenetic relationships of the damselfly Platycnemis pennipes in Europe based on 618 bp DNA from the mitochondrial gene COI. A haplotype network analysis shows that the species is divided into two haplotype groups. One is restricted to the Italian Peninsula, while the other is found from the Black Sea region across eastern and central Europe to Scandinavia, England, and southwestern France. This pattern is recovered in a Bayesian phylogenetic analysis. Genetic distance (K2P) between the two groups is approximately 1.5%, while within-group variation is an order of magnitude lower. An analysis of the molecular variance (AMOVA) shows that variation between the two groups account for more than 96% of the total variation within the dataset, adding to the evidence that they have been isolated for a considerable amount of time. The pattern we find is similar to the so-called Grasshopper Paradigm in European phylogeography, where a species has recolonized Europe after the last glaciation from a glacial refugium in the southeast, while other refugial populations in the Iberian and Italian peninsulas have remained isolated to this day. In P. pennipes there is only an isolated refugial population in Italy as the species does not have current populations in the Iberian Peninsula. By comparing the genetic distance between the two groups to a previously published divergence time analysis of European Odonata we estimate that they have likely been isolated since the onset of the Saale Glaciation ca 400 ky ago.
A Data Quality Framework for the European Health Data Space for secondary use
A cornerstone in the development of the European Health Data Space for secondary use of data (EHDS2) is the design, implementation and assessment of a Data Quality Framework (DQF). Consistently, the Joint Action TEHDAS has a dedicated work program where, learning from others’ experiences across Europe and abroad, the work package is building the concepts and methods for such a DQF. The scope of this work program is to provide recommendation to the Member States and the European Commission on the concept of DQF to foster, where (institutions) the DQF should be implemented, when in data life cycle, how should be implemented and by whom. In terms of the concept, the DQF raises the importance of quality assurance procedures at data processor level and the level of quality of the data collections in terms of reliability, relevance, timeliness, coherence, coverage and completeness. When it comes to when along the data life cycle, DQF is expected operate when data needs harmonization at data processor level (ie, the effective application of interoperability standards), in the publication of the data sources (ie providing users knowledge on the provenance of data and the content of data source); or, when data sources have to be integrated and sensitive data pseudonymized (ie, the quality of the linkage and losses after pseudonymisation). Finally, when it comes to the methodology, TEHDAS suggests a three-fold approach - some quality measures in the DQF could be translated into legislation (eg, the requirement of regular auditing for a data processor to be a trusted party in the EDHS2); some could be kept as good-practices (eg, recommendation of archival procedures when a research project finalizes); and, under the assumption of continuous data quality improvement, an assessment, benchmarking and promotion methodology (eg, a grading system at data processor level).
The fracture toughness of polymer cellulose nanocomposites using the essential work of fracture method
This work reinforced both a glassy polymer (high stiffness matrix) and a rubbery polymer (low stiffness matrix) with cellulose nanocrystals (CNC) derived from natural sources. CNC addition always increased stiffness while it increased toughness for a rubbery polymer and caused no loss in toughness for a glassy polymer. These results contradict many claims that when stiffness increases, the toughness decreases. We show that these claims depend on how toughness is measured. Our results were based on toughness measured using the essential work of fracture method. In contrast, toughness determined from area under the stress–strain curve shows a significant decrease, but that method may be a poor measure of toughness. Property enhancements usually require a good fiber/matrix interface. We used modeling of stiffness properties to confirm that CNC has a good interface with the studied polymer matrices.
Enrichment of Variations in KIR3DL1/S1 and KIR2DL2/L3 among H1N1/09 ICU Patients: An Exploratory Study
Infection by the pandemic influenza A (H1N1/09) virus resulted in significant pathology among specific ethnic groups worldwide. Natural Killer (NK) cells are important in early innate immune responses to viral infections. Activation of NK cells, in part, depend on killer-cell immunoglobulin-like receptors (KIR) and HLA class I ligand interactions. To study factors involved in NK cell dysfunction in overactive immune responses to H1N1 infection, KIR3DL1/S1 and KIR2DL2/L3 allotypes and cognate HLA ligands of H1N1/09 intensive-care unit (ICU) patients were determined. KIR3DL1/S1, KIR2DL2/L3, and HLA -B and -C of 51 H1N1/09 ICU patients and 105 H1N1-negative subjects (St. Theresa Point, Manitoba) were characterized. We detected an increase of 3DL1 ligand-negative pairs (3DL1/S1(+) Bw6(+) Bw4(-)), and a lack of 2DL1 HLA-C2 ligands, among ICU patients. They were also significantly enriched for 2DL2/L3 ligand-positive pairs (P<0.001, Pc<0.001; Odds Ratio:6.3158, CI95%:2.481-16.078). Relative to St. Theresa aboriginals (STh) and Venezuelan Amerindians (VA), allotypes enriched among aboriginal ICU patients (Ab) were: 2DL3 (Ab>VA, P=0.024, Pc=0.047; Odds Ratio:2.563, CI95%:1.109-5.923), 3DL1*00101 (Ab>VA, P<0.001, Pc<0.001), 3DL1*01502 (Ab>STh, P=0.034, Pc=0.268), and 3DL1*029 (Ab>STh, P=0.039, Pc=0.301). Aboriginal patients ligand-positive for 3DL1/S1 and 2DL1 had the lowest probabilities of death (R(d)) (R(d)=28%), compared to patients that were 3DL1/S1 ligand-negative (R(d)=52%) or carried 3DL1*029 (R(d)=52%). Relative to Caucasoids (CA), two allotypes were enriched among non-aboriginal ICU patients (NAb): 3DL1*00401 (NAb>CA, P<0.001, Pc<0.001) and 3DL1*01502 (CA
Comparative phylogeography uncovers evolutionary past of Holarctic dragonflies
Here, we investigate the evolutionary history of five northern dragonfly species to evaluate what role the last glaciation period may have played in their current distributions. We look at the population structure and estimate divergence times for populations of the following species: Aeshna juncea (Linnaeus), Aeshna subarctica Walker, Sympetrum danae (Sulzer), Libellula quadrimaculata Linnaeus and Somatochlora sahlbergi Trybom across their Holarctic range. Our results suggest a common phylogeographic pattern across all species except for S. sahlbergi . First, we find that North American and European populations are genetically distinct and have perhaps been separated for more than 400,000 years. Second, our data suggests that, based on genetics, populations from the Greater Beringian region (Beringia, Japan and China) have haplotypes that cluster with North America or Europe depending on the species rather than having a shared geographic affinity. This is perhaps a result of fluctuating sea levels and ice sheet coverage during the Quaternary period that influenced dispersal routes and refugia. Indeed, glacial Beringia may have been as much a transit zone as a refugia for dragonflies. Somatochlora sahlbergi shows no genetic variation across its range and therefore does not share the geographic patterns found in the other circumboreal dragonflies studied here. Lastly, we discuss the taxonomic status of Sympetrum danae , which our results indicate is a species complex comprising two species, one found in Eurasia through Beringia, and the other in North America east and south of Beringia. Through this study we present a shared history among different species from different families of dragonflies, which are influenced by the climatic fluctuations of the past.
Dientamoeba fragilis in Denmark: epidemiological experience derived from four years of routine real-time PCR
The intestinal protozoon Dientamoeba fragilis remains a clinical entity of dubious significance. While several previous studies address questions of epidemiology, only a handful have systematically employed and reported on the results from real-time polymerase chain reaction (qPCR), the best currently available diagnostic modality, and the comparison of results from different studies is, therefore, difficult. Since 2007, Statens Serum Institut (Denmark) has utilised qPCR for D . fragilis as routine diagnostic work-up for intestinal parasitosis, testing more than 22,000 samples from 2008 through 2011, and the aim of this study was to report on the results and experiences gained in the process. We demonstrate a staggeringly high proportion (43 %) of investigated patients positive for D . fragilis , ranging from 12 to 71 % depending on age group, showing a bimodal age distribution peaking in children and adults of parental age, as well as a clear association between exposure to children and risk of D . fragilis infection. We discuss these findings in light of the pinworm egg vector hypothesis and substantiate further our knowledge of risk factors pertaining to D . fragilis carriage.