92 research outputs found

    JJ-factors for self-interacting dark matter in 20 dwarf spheroidal galaxies

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    Dwarf spheroidal galaxies are among the most promising targets for indirect dark matter (DM) searches in γ\gamma-rays. The γ\gamma-ray flux from DM annihilation in a dwarf spheroidal galaxy is proportional to the JJ-factor of the source. The JJ-factor of a dwarf spheroidal galaxy is the line-of-sight integral of the DM mass density squared times σannvrel/(σannvrel)0\langle \sigma_{\rm ann} v_{\rm rel} \rangle/(\sigma_{\rm ann} v_{\rm rel})_0, where σannvrel\sigma_{\rm ann} v_{\rm rel} is the DM annihilation cross-section times relative velocity vrel=vrelv_{\rm rel}=|{\bf v}_{\rm rel}|, angle brackets denote average over vrel{\bf v}_{\rm rel}, and (σannvrel)0(\sigma_{\rm ann} v_{\rm rel})_0 is the vrelv_{\rm rel}-independent part of σannvrel\sigma_{\rm ann} v_{\rm rel}. If σannvrel\sigma_{\rm ann} v_{\rm rel} is constant in vrelv_{\rm rel}, JJ-factors only depend on the DM space distribution in the source. However, if σannvrel\sigma_{\rm ann} v_{\rm rel} varies with vrelv_{\rm rel}, as in the presence of DM self-interactions, JJ-factors also depend on the DM velocity distribution, and on the strength and range of the DM self-interaction. Models for self-interacting DM are increasingly important in the study of the small scale clustering of DM, and are compatible with current cosmological observations. Here we derive the JJ-factor of 20 dwarf spheroidal galaxies from stellar kinematic data under the assumption of Yukawa DM self-interactions. JJ-factors are derived through a profile Likelihood approach, assuming either NFW or cored DM profiles. We also compare our results with JJ-factors derived assuming the same velocity for all DM particles in the target galaxy. We find that this common approximation overestimates the JJ-factors by up to one order of magnitude. JJ-factors for a sample of DM particle masses, self-interaction coupling constants and density profiles are provided electronically, ready to be used in other projects.Comment: 10 pages, 3 figures and 2 table

    Growth rate and behaviour in separated, partially separated or non-separated kids and the corresponding milk production of their mothers

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    We address the hypothesis that keeping kids and mothers together would have positive effects on the milk composition of the mother and the behaviour of the kids. Kids were either permanently separated (SEP), daily separated between 7.30 and 15 h (DAY-SEP) or kept with mothers 24 h/d (NON-SEP). The NON-SEP kids were only allowed to suckle one teat. All kids had similar growth rate throughout the study (lactation days 5–70). DAY-SEP kids spent 24% of their time with their mother at both ages. NON-SEP spent only 15% of the time with their mothers at 2 weeks of age and this increased to 28% at 2 months of age. NON-SEP kids showed more hiding behaviour at 2 weeks and SEP were more active alone, at both 2 weeks and 2 months, compared to the other treatments. The mean available milk yield and fat concentration were higher in DAY-SEP goats (2420 g ± 119 g and 4.9 ± 0.1%) compared with NON-SEP goats (2149 ± 79 g and 4.4 ± 0.1%). There were no differences between DAY-SEP and NON-SEP goats in total protein, lactose, or casein concentrations. Based on these data it was estimated that 7.1 kg milk was needed to produce 1 kg semi-hard cheese in DAY-SEP goats and 7.5 kg in NON-SEP goats, respectively. When comparing milk yield and composition between udder halves, the milk yield was, as expected, higher from the machine milked teat than from the suckled one in the NON-SEP goats but there was no difference between right and left udder halves in DAY-SEP goats. Milk fat concentration varied between teats at morning and afternoon milkings in NON-SEP goats, but there was no difference in milk fat between udder-halves in DAY-SEP goats. In conclusion, the kid growth rate was similar in all treatments, however, an altered behaviour was seen in permanently separated kids (SEP). The results show that it is possible to have a high milk yield and fat concentration with one kid together with the dam

    DNA Coated Nanoparticle Eight-mers as Programmable Self-Assembly Building Blocks

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    Abstract. Nanoparticles coated with single stranded DNA have been shown to efficiently hybridize to targets of complementary DNA. This property might be used to implement programmable (or algorithmic-) self-assembly to build nanoparticle structures. However, we argue that a DNA coated nanoparticle by itself cannot be used as a programmable self-assembly building block since it does not have directed bonds. A general scheme for assembling and purifying nanoparticle eight-mers with eight geometrically well-directed bonds is presented together with some preliminary experimental work

    A DNA-nanoassembly-based approach to map membrane protein nanoenvironments

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    Most proteins at the plasma membrane are not uniformly distributed but localize to dynamic domains of nanoscale dimensions. To investigate their functional relevance, there is a need for methods that enable comprehensive analysis of the compositions and spatial organizations of membrane protein nanodomains in cell populations. Here we describe the development of a non-microscopy based method for ensemble analysis of membrane protein nanodomains. The method, termed NANOscale DEciphEring of membrane Protein nanodomains (NanoDeep), is based on the use of DNA nanoassemblies to translate membrane protein organization information into a DNA sequencing readout. Using NanoDeep, we characterised the nanoenvironments of Her2, a membrane receptor of critical relevance in cancer. Importantly, we were able to modulate by design the inventory of proteins analysed by NanoDeep. NanoDeep has the potential to provide new insights into the roles of the composition and spatial organization of protein nanoenvironments in the regulation of membrane protein function.EC Seventh Framework Programme FP7 (617711/EC)European Research Council (FP7-IDEAS-ERC)Knut and Alice Wallenberg Foundation (KAW 2017.0114)Swedish Research Council (2015-03520)Accepte
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