Dark Matter And The Dinosaurs Epub 17

The study of fossil feathers has been revitalized in the last few decades and has contributed significantly to paleontological studies of dinosaurs and birds. Specific morphological and physicochemical characteristics of the microscale structures of feathers and the protein keratin are key targets when preserved during the fossilization process. Keratin is a fibrous protein that composes some hard tissues such as hair, nails and feathers. It is part of the so called intermediate filaments inside keratinocyte cells and is rich in sulfur containing amino acid cysteine. To date, different microscopy and analytical methods have been used for the analysis and detailed characterization and classification of feathers. However, in this work we showed that analytical optical and electron microscopies can be quick and precise methods with minimal effects on the sample during analysis. This association of different approaches on the same sample results in correlative data albeit in different length scales. Intracellular bodies called melanosomes originally present in melanocyte cells were identified with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), and had well-defined orientation and a mean aspect ratio comparable to melanosomes extant in dark feathers. The detection of sulphur in melanosomes via Energy Dispersive Spectroscopy both in SEM and TEM shows that, along the fossilization process, sulphur from the degraded keratin matrix could have been trapped inside the melanosomes. Chemical groups that make up keratin and melanin in the fossil sample were detected via FT-IR Spectroscopy and Confocal Laser Scanning Microscopy (CLSM). The use of combined analytical microscopy techniques can contribute significantly to the study of fossils generating precise results with minimum damage to the original sample.

Sixty-six million years ago, an object the size of a city descended from space to crash into Earth, creating a devastating cataclysm that killed off the dinosaurs, along with three-quarters of the other species on the planet. What was its origin? In Dark Matter and the Dinosaurs, Lisa Randall proposes it was a comet that was dislodged from its orbit as the Solar System passed through a disk of dark matter embedded in the Milky Way. In a sense, it might have been dark matter that killed the dinosaurs.

dark matter and the dinosaurs epub 17

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There are some stories we just keep coming back to: myths of great heroes, of Chosen Ones who save the world, of sources of light that lead us from the dark. These stories as passed down through generation and take many forms: some are told many times with slight changes to suit the times, some are changed to make the hero look more like the storyteller. Some become songs or plays or films. But no matter the shape these stories take, their core themes stay the same, and we relate to them over and over again.

Strategy for detecting and annotating repeats in galGal4. Our strategy comprised five successive steps: 1, definition of the number of repeats; 2, number of SSRs; 3, number of TEs; 4, definition of dark matter; 5, definition of CNVs. The final products of each of these 5 steps were stored in the bed or gff annotation files (yellow boxes). Arrows show the chronology of events in the processes in each step. Black ellipses show the various states of the genome analysed; blue boxes indicate the programs used; green boxes indicate the intermediate library produced by a given process; red boxes indicate the end of a process before editing the bed or gff annotation files. The purple box in step 5 indicates the source of the annotation file used for CNVs 2ff7e9595c