Bloom Syndrome, a rare human disorder characterized by genomic instability and predisposition to cancer, is caused by mutation of BLM, which encodes a RecQ-family DNA helicase. The Drosophila melanogaster ortholog of BLM, DmBlm, is encoded by mus309. Mutations in mus309 cause hypersensitivity to DNA-damaging agents, female sterility, and defects in repairing double-strand breaks (DSBs). To better understand these phenotypes, we isolated novel mus309 alleles. Mutations that delete the N terminus of DmBlm, but not the helicase domain, have DSB repair defects as severe as those caused by null mutations. We found that female sterility is due to a requirement for DmBlm in early embryonic cell cycles; embryos lacking maternally derived DmBlm have anaphase bridges and other mitotic defects. These defects were less severe for the N-terminal deletion alleles, so we used one of these mutations to assay meiotic recombination. Crossovers were decreased to about half the normal rate, and the remaining crossovers were evenly distributed along the chromosome. We also found that spontaneous mitotic crossovers are increased by several orders of magnitude in mus309 mutants. These results demonstrate that DmBlm functions in multiple cellular contexts to promote genome stability.

THEPRESENT STUDY EXAMINES BOTH GRADUAL and rapid changes occurring in 20th-century jazz harmonic practice. A newly-assembled corpus of 1,086 jazz compositions was used to test the idea that jazz music exhibits a mid-century decline in traditionally "tonal" chord usage. Evidence was found for slow, incremental changes in zeroth-order chord quality distributions, consistent with gradual, unconscious changes in harmonic usage. Typical tonal chord-to-chord transitions became less common between the 1920s and the 1960s, consistent with the hypothesis of tonal decline. Einally, use of root motion of an ascending perfect fourth dropped suddenly in the 1950s, suggesting that chordto-chord transitions might be more susceptible to rapid change than chord frequency. Possible constraints on stylistic evolution are discussed.

W E CONDUCTED FOUR TESTS OF THE CONJECTURE that higher musical pitch coincides with faster musical speeds in composition and performance. First, a 'notewise' examination of Western musical scores tested whether longer (i.e., slower) notes tend to have lower pitches. Results were genre-dependent, with three of six sampled styles exhibiting the predicted effect. A second study considered an independent sample of Western music part-by-part and found that lower musical voices tend to have significantly fewer notes than higher voices. The third study used instrumental recordings to directly measure event onset densities in notes per second. A strong correlation (r^ = .74, p < .002) between performed note speed and an instrument's pitch range (tessitura) was found. Finally, a fourth study indicated that Baroque ornaments are more likely to appear in higher musical parts. Considered together, these four studies suggest a pitch-speed relationship that is most evident when the methodology preserves the notion of musical 'line.' We outline several possible origins for the observed effect.

THREE EXPERIMENTAL STUDIES SUGGEST THAT music with more musical voices (higher voice multiplicity) tends to be perceived more positively. In the first experiment, participants heard brief extracts from polyphonic keyboard works representing conditions of one, two, three, or four concurrent musical voices. Two basic emotions (happiness and sadness) and two social emotions (pride and loneliness) were rated on a continuous scale. Listeners rated excerpts with higher voice multiplicity as sounding more happy, less sad, less lonely, and more proud. Results from a second experiment indicate that this effect might extend to positive and negative emotions more generally. In a third experiment, participants were asked to count (denumerate) the number of musical voices in the same stimuli. Denumeration responses corresponded closely with ratings for both positive and negative emotions, suggesting that a single musical feature or percept might play a role in both. Possible roles for both symbolic and psychoacoustic musical features are discussed.

Theoretical and methodological perspectives are offered. Perceived personal involvement, variety of improvisational tools, and dramaturgy might be attributed to multimodal signals and cues of emotion, implicit learning of motor routines and musical tendency, and deliberate planning on the part of the musician. I give a personal perspective on my experience as an improvising musician, and suggest a sketch of how I imagine improvisation often works. Dramaturgical models meant for iteratively constructed artworks such as plays are likely to be deficient for improvisational artworks in general. Finally, the authors' methodological choices are considered. Both exploratory research and model selection are also driven by implicit hypotheses, so care must be taken to minimize false discovery.