42 research outputs found
High-resolution analysis of individual Drosophila melanogaster larvae uncovers individual variability in locomotion and its neurogenetic modulation
Neuronally orchestrated muscular movement and locomotion are defining faculties of multicellular animals. Due to its simple brain and genetic accessibility, the larva of the fruit fly Drosophila melanogaster allows one to study these processes at tractable levels of complexity. However, although the faculty of locomotion clearly pertains to the individual, most studies of locomotion in larvae use measurements aggregated across animals, or animals tested one by one, an extravagance for larger-scale analyses. This prevents grasping the inter- and intra-individual variability in locomotion and its neurogenetic determinants. Here, we present the IMBA (individual maggot behaviour analyser) for analysing the behaviour of individual larvae within groups, reliably resolving individual identity across collisions. We use the IMBA to systematically describe the inter- and intra-individual variability in locomotion of wild-type animals, and how the variability is reduced by associative learning. We then report a novel locomotion phenotype of an adhesion GPCR mutant. We further investigated the modulation of locomotion across repeated activations of dopamine neurons in individual animals, and the transient backward locomotion induced by brief optogenetic activation of the brain-descending âmooncrawlerâ neurons. In summary, the IMBA is an easy-to-use toolbox allowing an unprecedentedly rich view of the behaviour and its variability of individual larvae, with utility in multiple biomedical research contexts
Search for the Flavor-Changing Neutral Current Decay with the HERA-B Detector
We report on a search for the flavor-changing neutral current decay using events recorded with a dimuon trigger in
interactions of 920 GeV protons with nuclei by the HERA-B experiment. We find
no evidence for such decays and set a 90% confidence level upper limit on the
branching fraction .Comment: 17 pages, 4 figures (of which 1 double), paper to be submitted to
Physics Letters
Measurement of the J/Psi Production Cross Section in 920 GeV/c Fixed-Target Proton-Nucleus Interactions
The mid-rapidity (dsigma_(pN)/dy at y=0) and total sigma_(pN) production
cross sections of J/Psi mesons are measured in proton-nucleus interactions.
Data collected by the HERA-B experiment in interactions of 920 GeV/c protons
with carbon, titanium and tungsten targets are used for this analysis. The
J/Psi mesons are reconstructed by their decay into lepton pairs. The total
production cross section obtained is sigma_(pN)(J/Psi) = 663 +- 74 +- 46
nb/nucleon. In addition, our result is compared with previous measurements
Limits for the central production of Î+ and Îââ pentaquarks in 920-GeV pA collisions
We have searched for Î+(1540) and Îââ(1862) pentaquark candidates in proton-inducedreactions on C, Ti, and W targets at midrapidity and sâ=41.6ââGeV. In 2Ă108 inelastic eventswe find no evidence for narrow (Ïâ5ââMeV) signals in the Î+âpK0S and ÎâââÎâÏâ channels; our 95% C.L. upper limits (UL) forthe inclusive production cross section times branching fraction BâdÏ/dy $y â0 are (4-16) ÎŒb/N for a Î+ mass between 1521 and 1555 MeV,and 2.5ÎŒb/N for the Îââ. The UL of the yield ratio of Î+/Î(1520)<(3-12)% is significantly lower than model predictions.Our UL of BâÎââ/Î(1530)0<4% is at variance with the results that have provided the first evidencefor the Îââ