3,913 research outputs found
Relationally Aggressive Media Exposure and Childrenâs Normative Beliefs: Does Parental Mediation Matter?
Research indicates that relationally aggressive media exposure is positively associated with relational aggression in children. Theories of media effects suggest that these associations may be mediated by aggressive cognitions. Although parental mediation can attenuate the effects of violent media, it is unknown whether there are similar benefits of parental mediation of relationally aggressive media. The current study examined concurrent and longitudinal associations between relationally aggressive television and movie exposure and normative beliefs about relational aggression, and whether parental mediation moderates these associations. Participants were 103 children (50% female) in grades 3-6 and their parents. The following year, 48 children (52% female) were again assessed. Relationally aggressive media exposure predicted concurrent relational aggression norms, even after controlling for physically aggressive media exposure and physical aggression norms. Relationally aggressive television and movie exposure predicted greater subsequent approval of relational aggression only among children whose parents engaged in low levels of active mediation
Retention Effects of Biofilms in the River Rhine
The River Rhine is one of the most important navigation routes in Europe and has been affected by changes of the riverbed, in the form of canalization and straightening in the past. These changes have reduced and changed habitats for the river's flora and fauna, including the surfaces on which biofilms grow. Biofilms are found in all aquatic ecosystems and populate the contact layer between water and various substrates. These can be inorganic or organic substrates and are first colonized by bacteria, which initiate the formation of biofilms. The bacteria's excretion of extracellular polymeric substances (EPS) allows other organisms to attach to biofilms; in rivers, these are algae, flagellates, ciliates and various other organisms, which then feed on the biofilm and its inhabitants but also on the organisms and particles of the surrounding water. Biofilms as a habitat thus form a link between pelagic and benthic systems and therefore play an essential role in rivers.
In a model study over a period of one year, the effect of biofilms and their organisms on the abundances of various pelagic organisms was investigated using the River Rhine at Cologne as an example for a large European river in the potamal region. The design of the experimental setup eliminated the influence of macrofauna, which was previously thought to have the most significant impact on the reduction of planktonic organisms in rivers. The biofilms reduced the bacterial abundance in the water flowing through by 22 - 63 % (47 % on average) and thus cleaned an average of 10.9 * 103 liters of water per square meter of biofilm per day of bacteria. In addition, the retention of phytoplankton was 30 % and of planktonic heterotrophic flagellates 26 % on an annual average, resulting in an elimination rate of 6.7 * 103 L m-2 d-1 for phytoplankton and 5.8 * 103 L m-2 d-1 for planktonic heterotrophic flagellates, respectively. Examinations of the biofilms revealed that especially peritrich and heterotrich ciliates were most likely responsible for reducing bacteria from the pelagic. Centric and pennate diatoms represented another significant component of the biofilm biovolume attaching to the biofilm from the pelagic of the River Rhine and promoting the complex three-dimensional structure of the biofilms.
In a different part of the study, it was investigated whether the three-dimensional structure and the organisms of the biofilms can affect the retention or accumulation of microplastic particles and whether a transfer of microplastic particles via the food web to higher trophic levels is possible. The results of the experiments showd that biofilms had a significantly higher abundance of microplastic particles incorporated than other tested substrates, and up to 10,000 particles per square centimeter of biofilm could be embedded. Among the different size classes of microplastic particles tested (1 ”m, 6 ”m and 10 ”m), the abundance in biofilms increased with the size of microplastic particles. Feeding experiments with the model ciliate Stentor coeruleus dominating in the River Rhine showed high rates of uptake for larger particles. Further, it was shown that ciliates containing microplastic particles were ingested by gammarids and fish larvae resulting in the transfer of microplastic particles up the food chain.
The findings of the study highlight the role of biofilms in the river ecosystem. They serve as important sinks for bacteria (including pathogens). Further, they underline the necessity to preserve and enlarge surfaces for biofilm growth in river systems. On the other hand, microplastic particles can accumulate in biofilms, the consequences of this process still needs further investigations
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Multi-color pyrometer for materials processing in space
The design, construction and calibration of a computer-linked multicolor pyrometer is described. The device was constructed for ready adaptation to a spacecraft and for use in the control of thermal processes for manufacturing materials in space. The pyrometer actually uses only one color at a time, and is relatively insensitive to uncertainties in the heated object's emissivity because the product of the color and the temperature has been selected to be within a regime where the radiant energy emitted from the body increases very rapidly with temperature. The instrument was calibrated and shown to exceed its design goal of temperature measurements between 300 and 2000 C, and its accuracy in the face of imprecise knowledge of the hot object's emissivity was demonstrated
Identification and characterization of differentially expressed microRNAs in adult tissues of the long-lived Drosophila dilp2-3,5 mutant
MiRNAs sind kleine regulatorische MolekĂŒle, welche in Eukaryoten diverse Funktionen durch die Steuerung der Expression von Genen auf post-transkriptioneller Ebene in spezifischen Geweben ausĂŒben. In der Fruchtfliege Drosophila melanogaster sind 238 miRNAs annotiert, die nur vereinzelt funktionell charakterisiert sind. Einige miRNAs spielen eine Rolle in biologischen Prozessen des Alterns und stehen im direkten Zusammenhang mit altersmodulierenden Signaltransduktionswegen, zu denen auch der Insulin/IGF-Ă€hnliche Signalweg (IIS) zĂ€hlt. Ob miRNAs die phĂ€notypischen Effekte von reduziertem IIS, wie LebensverlĂ€ngerung und Resistenz gegenĂŒber Stressfaktoren, vermitteln, ist gĂ€nzlich unbekannt. FĂŒr eine umfangreiche Charakterisierung von miRNAs ist die Information ĂŒber gewebespezifische Expression unerlĂ€sslich. Bei der adulten Fliege wurden bisher nur Ovarien untersucht und es wurde zwischen der Expression in Köpfen und ganzen Körpern unterschieden. In der vorliegenden Arbeit wurden erstmals spezifische miRNA-Expressionsprofile der vier folgenden adulten Gewebe erstellt; des Gehirns, des Thorax, des Darmes und des Abdomens. Des Weiteren wurden in dieser Arbeit differenziell regulierte miRNAs in Geweben von langlebigen Drosophila dilp2-3,5-Mutanten identifiziert und mittels miRNA-Ăberexpressionsanalysen sowie einer im Rahmen dieser Arbeit generierten miRNA-Knockout-Mutante auf IIS-assoziierte PhĂ€notypen funktionell untersucht. Die vorliegende Arbeit leistet einen wesentlichen Beitrag zur Charakterisierung von miRNAs in Drosophila melanogaster im Allgemeinen, liefert insbesondere eine umfangreiche Analyse identifizierter differenziell regulierter miRNAs in langlebigen Insulin-Mutanten und trĂ€gt so zur AufklĂ€rung der dem Alterungsprozess zu Grunde liegenden biologischen Mechanismen bei.
MiRNAs are small regulatory molecules that execute diverse functions in eukaryotes through the post transcriptional control of gene expression in specific tissues. In the fruit fly Drosophila melanogaster 238 miRNAs are annotated and only few have been functionally characterized. Some miRNAs play a role in the biological processes of aging and are directly linked with aging modulating pathways including the insulin/IGF-like signaling (IIS) pathway. Whether miRNAs mediate phenotypic effects of reduced IIS remains unknown. For a comprehensive characterization of miRNA function, information about tissue-specific expression is indispensible which so far in the adult fly is limited to ovaries and the analysis of heads and whole bodies. In the present study for the first time miRNA expression profiles from four adult tissues including the brain, the thorax, the digestive tract and the abdomen were generated. Furthermore, differentially expressed miRNAs in tissues of the long-lived Drosophila dilp2-3,5 mutant were identified and functionally characterized for IIS-associated phenotypes by overexpression analysis and by a miRNA knock-out mutant generated within the scope of this study. The present study provides fundamental information for the characterization of miRNA function in Drosophila in general, supplies particularly an analysis of identified differentially expressed miRNAs in long-lived insulin mutants and thus contributes to the elucidation of biological mechanisms underlying the process of aging
A novel pH-sensitive liposome formulation containing oleyl alcohol
AbstractpH-sensitive liposomes are designed to undergo acid-triggered destabilization. First generation pH-sensitive liposomes, based on the cone-shaped lipid dioleoylphosphatidylethanolamine (DOPE), have been shown to lose fusogenicity in the presence of serum. Here, we report the design and evaluation of novel serum-resistant pH-sensitive liposome formulations that are based on the composition of egg phosphatidylcholine (PC), cholesteryl hemisuccinate (CHEMS), oleyl alcohol (OAlc), and Tween-80 (T-80). When loaded with the fluorescent probe calcein, these liposomes exhibited excellent stability at pH 7.4 and underwent rapid destabilization upon acidification as shown by calcein dequenching and particle size increase. Adjusting the mole percentages of T-80 and OAlc in the formulation could regulate the stability and pH-sensitive properties of these liposomes. Liposomes with a higher T-80 content exhibited greater stability but were less sensitive to acid-induced destabilization. Meanwhile, formulations with a higher OAlc content exhibited greater content release in response to low pH. The pH-triggered liposomal destabilization did not produce membrane fusion according to an octadecylrhodamine B chloride (R18) lipid-mixing assay. Compared to DOPE-based pH-sensitive liposomes, the above formulations showed much better retention of their pH-sensitive properties in the presence of 10% serum. These liposomes were then evaluated for intracellular delivery of entrapped cytosine-ÎČ-d-arabinofuranoside (araC) in KB human oral cancer cells, which have elevated folate receptor (FR) expression. The FR, which is amplified in many types of human tumors, has been shown to mediate the internalization of folate-derivatized liposomes into an acidic intracellular compartment. FR-targeted OAlc-based pH-sensitive liposomes, entrapping 200 mM araC, showed âŒ17-times greater FR-dependent cytotoxicity in KB cells compared to araC delivered via FR-targeted non-pH-sensitive liposomes. These data indicated that pH-sensitive liposomes based on OAlc, combined with FR-mediated targeting, are promising delivery vehicles for membrane impermeable therapeutic agents
Real-time ultrasound elastography in 180 axillary lymph nodes: elasticity distribution in healthy lymph nodes and prediction of breast cancer metastases
BACKGROUND: To determine the general appearance of normal axillary lymph nodes (LNs) in real-time tissue sonoelastography and to explore the methodâČs potential value in the prediction of LN metastases. METHODS: Axillary LNs in healthy probands (n=165) and metastatic LNs in breast cancer patients (n=15) were examined with palpation, B-mode ultrasound, Doppler and sonoelastography (assessment of the elasticity of the cortex and the medulla). The elasticity distributions were compared and sensitivity (SE) and specificity (SP) were calculated. In an exploratory analysis, positive and negative predictive values (PPV, NPV) were calculated based upon the estimated prevalence of LN metastases in different risk groups. RESULTS: In the elastogram, the LN cortex was significantly harder than the medulla in both healthy (p=0.004) and metastatic LNs (p=0.005). Comparing healthy and metastatic LNs, there was no difference in the elasticity distribution of the medulla (p=0.281), but we found a significantly harder cortex in metastatic LNs (p=0.006). The SE of clinical examination, B-mode ultrasound, Doppler ultrasound and sonoelastography was revealed to be 13.3%, 40.0%, 14.3% and 60.0%, respectively, and SP was 88.4%, 96.8%, 95.6% and 79.6%, respectively. The highest SE was achieved by the disjunctive combination of B-mode and elastographic features (cortex >3mm in B-mode or blue cortex in the elastogram, SE=73.3%). The highest SP was achieved by the conjunctive combination of B-mode ultrasound and elastography (cortex >3mm in B-mode and blue cortex in the elastogram, SP=99.3%). CONCLUSIONS: Sonoelastography is a feasible method to visualize the elasticity distribution of LNs. Moreover, sonoelastography is capable of detecting elasticity differences between the cortex and medulla, and between metastatic and healthy LNs. Therefore, sonoelastography yields additional information about axillary LN status and can improve the PPV, although this method is still experimental
Vacancy Diffusion in the Triangular Lattice Dimer Model
We study vacancy diffusion on the classical triangular lattice dimer model, sub ject to the kinetic constraint that dimers can only translate, but not rotate. A single vacancy, i.e. a monomer, in an otherwise fully packed lattice, is always localized in a tree-like structure. The distribution of tree sizes is asymptotically exponential and has an average of 8.16 \pm 0.01 sites. A connected pair of monomers has a finite probability of being delocalized. When delocalized, the diffusion of monomers is anomalous
Machbarkeitsstudie fĂŒr eine empirische Analyse von Hemmnissen fĂŒr die Verbreitung der betrieblichen Altersversorgung in kleinen und mittleren Unternehmen (Machbarkeitsstudie BAV in KMU) : Endbericht
Infolge der RentenreformmaĂnahmen in der Vergangenheit kann der Lebensstandard im Alter nicht mehr allein mit den Leistungen der gesetzlichen Rentenversicherung aufrechterhalten werden. Noch mehr als in der Vergangenheit sollte die Altersvorsorge im Rahmen der gesetzlichen Rentenversicherung durch zusĂ€tzliche Altersvorsorge im Rahmen der betrieblichen Altersversorgung und/oder der privaten Altersvorsorge ergĂ€nzt werden. Vor diesem Hintergrund besteht ein groĂes Interesse, mehr ĂŒber die Ursachen der geringeren Verbreitung von BAV-Lösungen in kleinen und mittleren Unternehmen, insbesondere in Kleinstunternehmen, zu erfahren und möglichst konkrete Ansatzpunkte zur Steigerung des Verbreitungsgrades der BAV bei den Unternehmen und deren Arbeitnehmern zu finden
Validating a screening agar for linezolidresistant enterococci
Background: Linezolid is an alternative treatment option for infections with multidrug-resistant Gram-positive bacteria
including vancomycin-resistant enterococci. Some countries report an increasing number of isolates with resistance to
linezolid. The recent publication of the Commission for Hospital Hygiene in Germany on enterococci/VRE recommends
screening for linezolid-resistant enterococci (LRE). However, a suitable selective medium or a genetic test is not
available. Our aim was to establish a selective screening agar for LRE detection and validate its application with a
comprehensive collection of clinical LRE and linezolid-susceptible enterococci.
Methods: We decided to combine the selective power of an enterococcal screening agar with a supplementation of
linezolid. Several rounds of analyses with reference, control and test strains and under varying linezolid concentrations
of a wider and a smaller range were investigated and assessed. The collection of linezolid-resistant enterococcal control
strains included isolates with different resistance mechanisms (23S rDNA mutations, cfr(B), optrA, poxtA). Finally, we
validated our LRE screening agar with 400 samples sent to our National Reference Centre in 2019.
Results: Several rounds of pre-tests and confirmatory analyses favored EnterococcoselÂź Agar supplemented with a
concentration of 2 mg/L linezolid. A 48 h incubation period was essential for accurate identification of LRE strains.
Performance of the LRE screening agar revealed a sensitivity of 96.6% and a specificity of 94.4%.
Conclusions: Here we describe preparation of a suitable screening agar and a procedure to identify LRE isolates with
high accuracyPeer Reviewe
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