Music information: the need for a central music licensing database

Musical Digital Service Providers (DSPs), like Pandora and Spotify, rely on a patchwork of databases and services to acquire licenses for the music they play. This results in both inefficiency and an unfair advantage to parties that have the leverage to negotiate better terms than their independent counterparts. A universal music database would be a giant step toward rectifying this inequality, as well as lowering the barrier to entry for new DSPs. Here, the main obstacles for such a system are laid out, as well as a possible scheme for such a universal database that includes the most recent technological developments in this field

Applications of high-throughput sequencing to chromatin structure and function in mammals

High-throughput DNA sequencing approaches have enabled direct interrogation of chromatin samples from mammalian cells. We are beginning to develop a genome-wide description of nuclear function during development, but further data collection, refinement, and integration are needed

Understanding Early Diagenetic Silicification: Petrographic Fabrics within Proterozoic Microfossiliferous Chert

Early diagenetic chert is abundant in Proterozoic carbonate successions and provides a critical window into organic preservation; the depositional origin of this chert, however, remains uncertain. There have been relatively few detailed petrographic analyses of Proterozoic microfossiliferous chert, which limits our understanding of both primary depositional fabrics, and of petrographic change during post-depositional recrystallization. The ~1.1 Ga Angmaat Formation, northern Baffin Island, Canada, contains abundant early diagenetic chert that contains exquisitely preserved microbial assemblages. Petrographic analysis indicates that chert is composed of four primary phases: chalcedony spherules that replace the majority of primary microbial and sedimentary elements, equigranular microcrystalline quartz which occurs as a minor component in the groundmass, chalcedony that lines primary voids within the depositional fabric, and megaquartz that occurs within chalcedony-lined voids. Here we present a detailed petrographic characterization of chert within the Angmaat Formation to better understand the mechanism of formation and potential pathway of diagenesis. Observations suggest that the silicification process began with formation of a silica gel within benthic microbial mats and associated carbonate sediment. We suggest that gel formation was intimately associated with the presence of organic matter (e.g., microbes and associated EPS), and that constructional voids (e.g., gas bubbles) within the mat remained free of silica gel. Polymeric linkages within the gel phase appear to have provided sufficient structure for precipitation of spherules as opal-CT, rather than as opal-A, thus resulting in minimal water loss associated with post-depositional recrystallization to chalcedony which favored exquisite microfossil preservation

Systematic analysis of off-target effects in an RNAi screen reveals microRNAs affecting sensitivity to TRAIL-induced apoptosis.

BACKGROUND: RNA inhibition by siRNAs is a frequently used approach to identify genes required for specific biological processes. However RNAi screening using siRNAs is hampered by non-specific or off target effects of the siRNAs, making it difficult to separate genuine hits from false positives. It is thought that many of the off-target effects seen in RNAi experiments are due to siRNAs acting as microRNAs (miRNAs), causing a reduction in gene expression of unintended targets via matches to the 6 or 7 nt 'seed' sequence. We have conducted a careful examination of off-target effects during an siRNA screen for novel regulators of the TRAIL apoptosis induction pathway(s). RESULTS: We identified 3 hexamers and 3 heptamer seed sequences that appeared multiple times in the top twenty siRNAs in the TRAIL apoptosis screen. Using a novel statistical enrichment approach, we systematically identified a further 17 hexamer and 13 heptamer seed sequences enriched in high scoring siRNAs. The presence of one of these seeds sequences (which could explain 6 of 8 confirmed off-target effects) is sufficient to elicit a phenotype. Three of these seed sequences appear in the human miRNAs miR-26a, miR-145 and miR-384. Transfection of mimics of these miRNAs protects several cell types from TRAIL-induced cell death. CONCLUSIONS: We have demonstrated a role for miR-26a, miR-145 and miR-26a in TRAIL-induced apoptosis. Further these results show that RNAi screening enriches for siRNAs with relevant off-target effects. Some of these effects can be identified by the over-representation of certain seed sequences in high-scoring siRNAs and we demonstrate the usefulness of such systematic analysis of enriched seed sequences

Can Protostellar Outflows Set Stellar Masses?

The opening angles of some protostellar outflows appear too narrow to match the expected core-star mass efficiency SFE = 0.3-0.5 if outflow cavity volume traces outflow mass, with a conical shape and a maximum opening angle near 90 deg. However, outflow cavities with paraboloidal shape and wider angles are more consistent with observed estimates of the SFE. This paper presents a model of infall and outflow evolution based on these properties. The initial state is a truncated singular isothermal sphere which has mass $\approx$1 $M_\odot$, free fall time $\approx$80 kyr, and small fractions of magnetic, rotational, and turbulent energy. The core collapses pressure-free as its protostar and disk launch a paraboloidal wide-angle wind. The cavity walls expand radially and entrain envelope gas into the outflow. The model matches SFE values when the outflow mass increases faster than the protostar mass by a factor 1 - 2, yielding protostar masses typical of the IMF. It matches observed outflow angles if the outflow mass increases at nearly the same rate as the cavity volume. The predicted outflow angles are then typically $\sim$50 deg as they increase rapidly through the stage 0 duration of $\sim$40 kyr. They increase more slowly up to $\sim$110 deg during their stage I duration of $\sim$70 kyr. With these outflow rates and shapes, model predictions appear consistent with observational estimates of typical stellar masses, SFEs, stage durations, and outflow angles, with no need for external mechanisms of core dispersal.Comment: Accepted for publication by The Astrophysical Journal; 47 pages, 10 figure

Protostellar accretion traced with chemistry. High resolution C18O and continuum observations towards deeply embedded protostars in Perseus

Context: Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims: To characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods: A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program "Mass Assembly of Stellar Systems and their Evolution with the SMA" (MASSES). The size of the C$^{18}$O emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether a link can be established between accretion bursts and massive circumstellar disks. Results: Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C$^{18}$O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C$^{18}$O emission, we estimate an average interval between bursts of 20000-50000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.Comment: Accepted for publication in A&A, 21 pages, 13 figure