792 research outputs found

    Access for All?:Sozialinvestitionen in der frühkindlichen Bildung und Betreuung im europäischen Vergleich

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    Recently, the quantum nature in the energy transport in solar cells and light-harvesting complexes has attracted much attention as being triggered by the experimental observations. We model the light-harvesting complex (i.e., PEB<sub>50</sub> dimer) as a quantum heat engine (QHE) and study the effect of the undamped intramolecule vibrational modes on the coherent energy-transfer process and quantum transport. We find that the exciton–vibration interaction has <i>nontrivial</i> contribution to the promotion of quantum yield as well as transport properties of the QHE at steady state by enhancing the quantum coherence quantified by entanglement entropy. The perfect quantum yield over 90% has been obtained, with the exciton–vibration coupling. We attribute these improvements to the renormalization of the electronic couplings effectively induced by exciton–vibration interaction and the subsequent delocalization of excitons. Finally, we demonstrate that the thermal relaxation and dephasing can help the excitation energy transfer in the PEB<sub>50</sub> dimer

    NOS Snaplines, het journaal voor jongeren?

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    Door het gebruik van nieuwe media in de journalistiek, zoals Snapchat, rijst de vraag wat dit doet met de journalistieke content. Snapchat heeft zeer specifieke eigenschappen: content moet live zijn, content verdwijnt weer (Bayer et al, 2015) en er zijn allerlei bewerkingstools aanwezig (Piwerk en Joinson, 2016). Snapchat is erg populair onder jongeren en het is daarom niet gek dat een nieuwsorganisatie als de NOS Snapchat gebruikt om die doelgroep te bereiken. In eerdere onderzoeken naar blogs (Singer, 2005) en Twitter (Lasorsa et al, 2012) werd onderzocht in hoeverre een nieuw medium de journalistieke normen van onpartijdigheid, transparantie en gatekeeping schaadt. Uit deze onderzoeken bleek dat journalisten grofweg dezelfde journalistieke normen en werkwijze handhaafden op blogs als binnen traditionele journalistiek, maar dat dit op Twitter veranderde. Journalisten gebruikten enerzijds hun traditionele normen binnen Twitter, maar pasten zich ook aan Twitter aan. In dit onderzoek zijn 186 snaps van NOS Snaplines geanalyseerd aan de hand van de drie begrippen: onpartijdigheid, transparantie en gatekeeping. Uit de resultaten blijkt NOS Snaplines relatief onpartijdig wanneer het gaat om tekst. Wanneer er naar bewerkingstools zoals emoji’s en stickers wordt gekeken, blijkt dat deze bewerkingen de snaps wel partijdig maken. Deze bewerkingstools kunnen namelijk ook emoties of meningen verkondigen. Eerder onderzoek stelt dat journalisten een manier zoeken om emoties uit te besteden. Dit kan een journalist doen door niet zijn eigen emoties op te schrijven, maar de emoties van een ander (Wahl-Jorgensen). Er zou in het geval van NOS Snaplines gesteld kunnen worden dat emoties worden uitbesteed aan eigenschappen van een medium, door bijvoorbeeld emoji’s binnen Snapchat in te zetten. NOS Snaplines blijkt uit de analyse over een lage mate van transparantie te beschikken, terwijl social media normaliter transparanter zijn dan traditionele media (Singer, 2005; Lasorsa et al, 2012). Hyperlinking maakt social media transparant, maar Snapchat heeft deze mogelijkheid niet. Toch zijn er andere manieren om transparant te zijn. Zo is Snapchat een medium waar juist alledaagse content, materiaal van achter de schermen en content vanaf locatie kan worden geplaatst, wat transparant kan worden bevonden maar weinig gebeurt in NOS Snaplines. Uit de analyse naar het derde begrip, gatekeeping, blijkt dat de rol van gatekeeper sterk wordt bewaakt binnen NOS Snaplines. Het podium wordt niet snel gedeeld. De begrippen onpartijdigheid, transparantie en gatekeeping lijken nog gehandhaafd te worden binnen Snapchat, in die zin kan gesteld worden dat de journalisten Snapchat ‘normalizen’. Ze zorgen dat hun eigen normen en waarden gebruikt kunnen worden in het nieuwe medium. Gesteld kan worden dat NOS Snaplines nog lijkt op een traditioneel achtuurjournaal, uit de analyse is gebleken dat zelfs de opbouw hetzelfde is. Maar aan de andere 3 kant gebruiken de Snaplines-redacteuren emoji’s en stickers die het nieuws partijdig maken. In eerder onderzoek naar Twitter viel op dat er minder waarde werd gehecht aan het concept van onpartijdigheid (Lasorsa et al 2012), wat ook het geval blijkt te zijn in NOS Snaplines. Dit duidt op het idee dat binnen sociale-mediajournalistiek voornamelijk de journalistieke norm van onpartijdigheid aan het veranderen is. Hoewel in de literatuur het dominante paradigma is dat subjectiviteit en emoties in nieuws beperkt moeten worden, zijn er ook tegengeluiden waarbij onderzoekers een positievere houding hebben tegenover emotionele (meer partijdige) journalistiek (Pantti, 2010; Wahl-Jorgensen, 2013; Opgenhaffen en Welbers, 2017). Want opiniërend, persoonlijk en subjectief nieuws kan een voordeel hebben op feitelijk nieuws omdat consumenten, zeker op social media, worden overspoeld met feitelijk nieuws. Een interpretatie kan dan een extra laag geven aan het objectieve nieuws (Marchi, 2012). Daarnaast blijkt uit de analyse dat de nieuwsonderwerpen die worden besproken vooral bestaan uit non-public affairs, oftewel nieuws dat aantrekkelijk is voor jongeren, maar waarvan journalisten normaliter denken dat het minder nieuwswaarde heeft (Boczkowski & Mitchelstein, 2010). Hoewel NOS Snaplines-redacteuren aan de ene kant hun journalistieke normen gebruiken binnen Snapchat, passen ze ook hun werkwijze aan Snapchat aan. Hieruit kan geconcludeerd worden dat redacteuren van NOS Snaplines op een andere manier journalistiek bedrijven en dat de journalistiek wel degelijk verandert door een nieuw medium als Snapchat

    Quantification of motor network dynamics in Parkinson’s disease by means of landscape and flux theory

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    <div><p>The basal ganglia neural circuit plays an important role in motor control. Despite the significant efforts, the understanding of the principles and underlying mechanisms of this modulatory circuit and the emergence of abnormal synchronized oscillations in movement disorders is still challenging. Dopamine loss has been proved to be responsible for Parkinson’s disease. We quantitatively described the dynamics of the basal ganglia-thalamo-cortical circuit in Parkinson’s disease in terms of the emergence of both abnormal firing rates and firing patterns in the circuit. We developed a potential landscape and flux framework for exploring the modulatory circuit. The driving force of the circuit can be decomposed into a gradient of the potential, which is associated with the steady-state probability distributions, and the curl probability flux term. We uncovered the underlying potential landscape as a Mexican hat-shape closed ring valley where abnormal oscillations emerge due to dopamine depletion. We quantified the global stability of the network through the topography of the landscape in terms of the barrier height, which is defined as the potential difference between the maximum potential inside the ring and the minimum potential along the ring. Both a higher barrier and a larger flux originated from detailed balance breaking result in more stable oscillations. Meanwhile, more energy is consumed to support the increasing flux. Global sensitivity analysis on the landscape topography and flux indicates how changes in underlying neural network regulatory wirings and external inputs influence the dynamics of the system. We validated two of the main hypotheses(direct inhibition hypothesis and output activation hypothesis) on the therapeutic mechanism of deep brain stimulation (DBS). We found GPe appears to be another effective stimulated target for DBS besides GPi and STN. Our approach provides a general way to quantitatively explore neural networks and may help for uncovering more efficacious therapies for movement disorders.</p></div

    Binary Crystallized Supramolecular Aerogels Derived from Host–Guest Inclusion Complexes

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    Aerogels with low density and high porosity show outstanding properties such as large surface area and low thermal and acoustic conductivity. However, great challenges remain to convert hydrophilic polymer based hydrogels to corresponding aerogels. Here, we report a structurally new type of aerogels, supramolecular aerogels (SMAs), derived from supramolecular hydrogels formed by self-assembling of poly(ethylene glycol) and α-/γ-cyclodextrin. The SMAs posses a characteristic binary crystallized nanosheet structure due to their supramolecular cross-linking nature, and their specific surface areas and nanosheet structures are tunable. Furthermore, we demonstrated application of the aerogels as solid–solid phase change materials with tunable latent heat, reversible melting-crystallization cycle while keeping the microstructure of the SMAs unchanged

    A Physical Mechanism and Global Quantification of Breast Cancer

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    <div><p>Initiation and progression of cancer depend on many factors. Those on the genetic level are often considered crucial. To gain insight into the physical mechanisms of breast cancer, we construct a gene regulatory network (GRN) which reflects both genetic and environmental aspects of breast cancer. The construction of the GRN is based on available experimental data. Three basins of attraction, representing the normal, premalignant and cancer states respectively, were found on the phenotypic landscape. The progression of breast cancer can be seen as switching transitions between different state basins. We quantified the stabilities and kinetic paths of the three state basins to uncover the biological process of breast cancer formation. The gene expression levels at each state were obtained, which can be tested directly in experiments. Furthermore, by performing global sensitivity analysis on the landscape topography, six key genes (HER2, MDM2, TP53, BRCA1, ATM, CDK2) and four regulations (HER2⊣TP53, CDK2⊣BRCA1, ATM→MDM2, TP53→ATM) were identified as being critical for breast cancer. Interestingly, HER2 and MDM2 are the most popular targets for treating breast cancer. BRCA1 and TP53 are the most important oncogene of breast cancer and tumor suppressor gene, respectively. This further validates the feasibility of our model and the reliability of our prediction results. The regulation ATM→MDM2 has been extensive studied on DNA damage but not on breast cancer. We notice the importance of ATM→MDM2 on breast cancer. Previous studies of breast cancer have often focused on individual genes and the anti-cancer drugs are mainly used to target the individual genes. Our results show that the network-based strategy is more effective on treating breast cancer. The landscape approach serves as a new strategy for analyzing breast cancer on both the genetic and epigenetic levels and can help on designing network based medicine for breast cancer.</p></div

    Specificity and Affinity Quantification of Flexible Recognition from Underlying Energy Landscape Topography

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    <div><p>Flexibility in biomolecular recognition is essential and critical for many cellular activities. Flexible recognition often leads to moderate affinity but high specificity, in contradiction with the conventional wisdom that high affinity and high specificity are coupled. Furthermore, quantitative understanding of the role of flexibility in biomolecular recognition is still challenging. Here, we meet the challenge by quantifying the intrinsic biomolecular recognition energy landscapes with and without flexibility through the underlying density of states. We quantified the thermodynamic intrinsic specificity by the topography of the intrinsic binding energy landscape and the kinetic specificity by association rate. We found that the thermodynamic and kinetic specificity are strongly correlated. Furthermore, we found that flexibility decreases binding affinity on one hand, but increases binding specificity on the other hand, and the decreasing or increasing proportion of affinity and specificity are strongly correlated with the degree of flexibility. This shows more (less) flexibility leads to weaker (stronger) coupling between affinity and specificity. Our work provides a theoretical foundation and quantitative explanation of the previous qualitative studies on the relationship among flexibility, affinity and specificity. In addition, we found that the folding energy landscapes are more funneled with binding, indicating that binding helps folding during the recognition. Finally, we demonstrated that the whole binding-folding energy landscapes can be integrated by the rigid binding and isolated folding energy landscapes under weak flexibility. Our results provide a novel way to quantify the affinity and specificity in flexible biomolecular recognition.</p></div

    Optimizing Scoring Function of Protein-Nucleic Acid Interactions with Both Affinity and Specificity

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    <div><p>Protein-nucleic acid (protein-DNA and protein-RNA) recognition is fundamental to the regulation of gene expression. Determination of the structures of the protein-nucleic acid recognition and insight into their interactions at molecular level are vital to understanding the regulation function. Recently, quantitative computational approach has been becoming an alternative of experimental technique for predicting the structures and interactions of biomolecular recognition. However, the progress of protein-nucleic acid structure prediction, especially protein-RNA, is far behind that of the protein-ligand and protein-protein structure predictions due to the lack of reliable and accurate scoring function for quantifying the protein-nucleic acid interactions. In this work, we developed an accurate scoring function (named as SPA-PN, SPecificity and Affinity of the Protein-Nucleic acid interactions) for protein-nucleic acid interactions by incorporating both the specificity and affinity into the optimization strategy. Specificity and affinity are two requirements of highly efficient and specific biomolecular recognition. Previous quantitative descriptions of the biomolecular interactions considered the affinity, but often ignored the specificity owing to the challenge of specificity quantification. We applied our concept of intrinsic specificity to connect the conventional specificity, which circumvents the challenge of specificity quantification. In addition to the affinity optimization, we incorporated the quantified intrinsic specificity into the optimization strategy of SPA-PN. The testing results and comparisons with other scoring functions validated that SPA-PN performs well on both the prediction of binding affinity and identification of native conformation. In terms of its performance, SPA-PN can be widely used to predict the protein-nucleic acid structures and quantify their interactions.</p></div

    The folding stability for folding with and without interfacial binding shown in (A) heat capacity curves and (B) free energy landscapes for Lambda Cro repressor (red) and Lambda repressor (blue).

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    <p>The solid and corresponding dotted lines represent isolated (independent) and dimeric (effective) folding respectively. Free energy landscapes are plotted at the isolated folding transition temperatures, which are calculated from the peaks of heat capacity curves for folding, respectively. Free energy is in reduced unit.</p

    Differentiation and reprogramming process represented by 313 nodes (every node denotes a cell state, characterized by expression patterns of the 22 marker genes) and 329 edges (paths).

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    <p>The sizes of nodes and edges are proportional to the occurrence probability of the corresponding states and paths, respectively. Red nodes represent states which are closer to stem cell states in terms of gene expression pattern, and blue nodes represent states which are closer to differentiation states. The green and magenta paths denote dominant kinetic paths from path integral separately for differentiation and reprogramming. Here, we set a probability cutoff to decrease the number of states and paths, i.e. we only demonstrate the states and paths with higher probability. The largest red node (high NANOG/low GATA6/low CDX2) represents most major ES state (stem cell state), and the largest blue node (low NANOG/high GATA6/high CDX2) represents most major differentiation state. IM1 represents a intermediate state (low NANOG/low GATA6/low CDX2), and IM2 represents another intermediate state (high NANOG/high GATA6/high CDX2).</p

    Optimization of SPA-PN.

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    <p>(A) Evolution of the success rate and the average interfacial RMSD () as the iteration precedes. (B) The distribution of ISR values calculated with pre-optimized SPA-PN and optimized SPA-PN respectively.</p
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