1,392 research outputs found

    Origin of the p-process radionuclides ⁹²Nb and ¹⁴⁶Sm in the early solar system and inferences on the birth of the Sun

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    The abundances of ⁹²Nb and ¹⁴⁶Sm in the early solar system are determined from meteoritic analysis, and their stellar production is attributed to the p process. We investigate if their origin from thermonuclear supernovae deriving from the explosion of white dwarfs with mass above the Chandrasekhar limit is in agreement with the abundance of ⁵³Mn, another radionuclide present in the early solar system and produced in the same events. A consistent solution for ⁹²Nb and ⁵³Mn cannot be found within the current uncertainties and requires the ⁹²Nb/⁹²Mo ratio in the early solar system to be at least 50% lower than the current nominal value, which is outside its present error bars. A different solution is to invoke another production site for ⁹²Nb, which we find in the α-rich freezeout during core-collapse supernovae from massive stars. Whichever scenario we consider, we find that a relatively long time interval of at least ∼10 My must have elapsed from when the star-forming region where the Sun was born was isolated from the interstellar medium and the birth of the Sun. This is in agreement with results obtained from radionuclides heavier than iron produced by neutron captures and lends further support to the idea that the Sun was born in a massive star-forming region together with many thousands of stellar siblings

    The acute phase protein, haptoglobin : a potential parameter in welfare assessment?

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    Physiological parameters are important measures in animal welfare assessment. To assess the amount of stress an animal experiences, stress hormones like cortisol are frequently used. However, measuring cortisol has major disadvantages due to its rapid reactivity and decline and many influencing factors. Other potential alternative markers are acute phase proteins, since stress is known to affect the immune system. A pilot study was conducted to investigate the response of the acute phase protein, plasma haptoglobine (HP), in pigs subjected to a stressor (food deprivation) and to examine the correlation between HP levels and average daily growth (ADG). Forty grower pigs (25.1 ± 4.4 kg, mean ± SD) (sex and former pen mates balanced), were allocated to 4 conventional pens, 2 treatment (T) and 2 control (C) groups (10 pigs per pen). After 10 days of adaptation the experiment started and ran for 3 weeks. In the 2nd week, T groups were repeatedly subjected to an 8-hour food deprivation (day 1, 3, 5 and 7 of week 2), C groups had normal, unrestricted, access to food. Pigs were weighed twice a week and blood was collected once a week (every 5th day). Mean levels of plasma HP of C and T groups showed large variation between individuals (C groups, week 2: 1.84 ± 3.11 mg/ml; T groups, week 2: 1.40 ± 1.16 mg/ml). No significant differences (Kruskal-Wallis test) in HP levels or growth were found between the C and T groups or between the different weeks within the T groups. Significant negative weak to moderate correlations were found between ADG and HP levels (HP week 1 and ADG week 1: rs = -0.47, p=0.005; HP week 2 and ADG total; rs= -0.60, p=0.015; HP week 3 and ADG total: rs = -0.43, p=0.025; average HP total and ADG total: rs= -0.41, p=0.017). Large variations in HP levels between individuals were shown and no effect of treatment on HP levels or growth was found. Possibly, food deprivation had no apparent stress eliciting effect. Despite these results, interesting correlations between the level of HP and ADG were found, corroborating the inverse relationship between the acute phase response and growth. To further investigate the relation of the acute phase response and stress a successive experiment will be conducted in which we apply a stronger stressor (mixing pigs) and combine the physiological data with behavior

    Datenmanagement und Data Sharing. Erfahrungen in den Sozial- und Wirtschaftswissenschaften

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    Die Menge der für Forschungszwecke zur Verfügung stehenden Daten vergrößert sich beständig (King, 2011). Jedoch werden unter Daten in den verschiedenen wissenschaftlichen Disziplinen ganz unterschiedliche Dinge gefasst. Aus dem lateinischen kommend bezeichnet ein Datum zunächst einmal etwas „Gegebenes“. In den Geowissenschaften können Daten Eisbohrkerne sein, aber auch numerische Geokoordinaten. In den Geschichtswissenschaften können Daten das Format alter Dokumente haben. In der Medizin können es auch biologische Proben oder Laborwerte sein. In den quantitativ empirisch arbeitenden Sozial-, Verhaltensund Wirtschaftswissenschaften ist das „gängige“ Format der einschlägigen Daten das von Zahlen als Teil von Datenmatrizen oder Tabellen...

    Parameters of low back pain chronicity among athletes: associations with physical and mental stress

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    Objective: In the general population, physical and mental stress factors are linked to chronic low back pain (LBP). The aim of the present study was to examine this association among athletes

    A Modular Plasmid Assembly Kit for Multigene Expression, Gene Silencing and Silencing Rescue in Plants

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    The Golden Gate (GG) modular assembly approach offers a standardized, inexpensive and reliable way to ligate multiple DNA fragments in a pre-defined order in a single-tube reaction. We developed a GG based toolkit for the flexible construction of binary plasmids for transgene expression in plants. Starting from a common set of modules, such as promoters, protein tags and transcribed regions of interest, synthetic genes are assembled, which can be further combined to multigene constructs. As an example, we created T-DNA constructs encoding multiple fluorescent proteins targeted to distinct cellular compartments (nucleus, cytosol, plastids) and demonstrated simultaneous expression of all genes in Nicotiana benthamiana, Lotus japonicus and Arabidopsis thaliana. We assembled an RNA interference (RNAi) module for the construction of intron-spliced hairpin RNA constructs and demonstrated silencing of GFP in N. benthamiana. By combination of the silencing construct together with a codon adapted rescue construct into one vector, our system facilitates genetic complementation and thus confirmation of the causative gene responsible for a given RNAi phenotype. As proof of principle, we silenced a destabilized GFP gene (dGFP) and restored GFP fluorescence by expression of a recoded version of dGFP, which was not targeted by the silencing construct

    Synthesis, structure and cytotoxicity of cyclic (alkyl)(amino) carbene and acyclic carbene complexes of group 11 metals

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    A series of complexes of cyclic (alkyl)(amino)carbene (CAAC) complexes of copper, silver and gold have been investigated for their antiproliferative properties. A second series of acyclic carbene (ACC) complexes of gold(I) were prepared by nucleophilic attack on isocyanide complexes by amines and amino esters, to give (ACC)AuCl, [(ACC)Au(PTA)]+ (PTA = triazaphosphaadamantane), as well as mixed-carbene compounds [(CAAC)Au(ACC)]+. Representative complexes were characterised by X-ray diffraction which confirmed the mononuclear linear structures without close intermolecular contacts or aurophilic interactions. The redox properties of these complexes have been determined. The compounds were tested against a panel of human cancer cell lines including leukemia (HL 60), breast adenocarcinoma cells (MCF-7) and human lung adenocarcinoma epithelial cell lines (A549), which show varying degrees of cisplatin resistance. The pro-ligand iminium salts and the PTA complexes were non-toxic. By contrast, the CAAC complexes show high cytotoxicity, with IC50 values in the sub-micromolar to ∼100 nanomolar range, even against cisplatin-insensitive MCF-7 and A549 cells. Cationic bis-carbene complexes [(Me2CAAC)2M]+ (6–8, M = Cu, Ag and Au) proved particularly effective. The mechanism of cell growth control by these complexes remains to be established, although possible modes of action such as inhibition of thioredoxin reductase (TrxR), which is a common pathway for gold NHC compounds, or the formation of reactive oxygen species (ROS) through redox processes, could be ruled out as primary pathways
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