5 research outputs found
Parametrization and Classification of 20 Billion LSST Objects: Lessons from SDSS
The Large Synoptic Survey Telescope (LSST) will be a large, wide-field
ground-based system designed to obtain, starting in 2015, multiple images of
the sky that is visible from Cerro Pachon in Northern Chile. About 90% of the
observing time will be devoted to a deep-wide-fast survey mode which will
observe a 20,000 deg region about 1000 times during the anticipated 10
years of operations (distributed over six bands, ). Each 30-second long
visit will deliver 5 depth for point sources of on average.
The co-added map will be about 3 magnitudes deeper, and will include 10 billion
galaxies and a similar number of stars. We discuss various measurements that
will be automatically performed for these 20 billion sources, and how they can
be used for classification and determination of source physical and other
properties. We provide a few classification examples based on SDSS data, such
as color classification of stars, color-spatial proximity search for wide-angle
binary stars, orbital-color classification of asteroid families, and the
recognition of main Galaxy components based on the distribution of stars in the
position-metallicity-kinematics space. Guided by these examples, we anticipate
that two grand classification challenges for LSST will be 1) rapid and robust
classification of sources detected in difference images, and 2) {\it
simultaneous} treatment of diverse astrometric and photometric time series
measurements for an unprecedentedly large number of objects.Comment: Presented at the "Classification and Discovery in Large Astronomical
Surveys" meeting, Ringberg Castle, 14-17 October, 200
A Yeast Modular Cloning (MoClo) Toolkit Expansion for Optimization of Heterologous Protein Secretion and Surface Display in Saccharomyces cerevisiae
Saccharomyces cerevisiae is an attractive
host for the expression of secreted proteins in a biotechnology context.
Unfortunately, many heterologous proteins fail to enter, or efficiently
progress through, the secretory pathway, resulting in poor yields.
Similarly, yeast surface display has become a widely used technique
in protein engineering but achieving sufficient levels of surface
expression of recombinant proteins is often challenging. Signal peptides
(SPs) and translational fusion partners (TFPs) can be used to direct
heterologous proteins through the yeast secretory pathway, however,
selection of the optimal secretion promoting sequence is largely a
process of trial and error. The yeast modular cloning (MoClo) toolkit
utilizes type IIS restriction enzymes to facilitate an efficient assembly
of expression vectors from standardized parts. We have expanded this
toolkit to enable the efficient incorporation of a panel of 16 well-characterized
SPs and TFPs and five surface display anchor proteins into S. cerevisiae expression cassettes. The secretion
promoting signals are validated by using five different proteins of
interest. Comparison of intracellular and secreted protein levels
reveals the optimal secretion promoting sequence for each individual
protein. Large, protein of interest-specific variations in secretion
efficiency are observed. SP sequences are also used with the five
surface display anchors, and the combination of SP and anchor protein
proves critical for efficient surface display. These observations
highlight the value of the described panel of MoClo compatible parts
to allow facile screening of SPs and TFPs and anchor proteins for
optimal secretion and/or surface display of a given protein of interest
in S. cerevisiae
A Yeast Modular Cloning (MoClo) Toolkit Expansion for Optimization of Heterologous Protein Secretion and Surface Display in Saccharomyces cerevisiae
Saccharomyces cerevisiae is an attractive
host for the expression of secreted proteins in a biotechnology context.
Unfortunately, many heterologous proteins fail to enter, or efficiently
progress through, the secretory pathway, resulting in poor yields.
Similarly, yeast surface display has become a widely used technique
in protein engineering but achieving sufficient levels of surface
expression of recombinant proteins is often challenging. Signal peptides
(SPs) and translational fusion partners (TFPs) can be used to direct
heterologous proteins through the yeast secretory pathway, however,
selection of the optimal secretion promoting sequence is largely a
process of trial and error. The yeast modular cloning (MoClo) toolkit
utilizes type IIS restriction enzymes to facilitate an efficient assembly
of expression vectors from standardized parts. We have expanded this
toolkit to enable the efficient incorporation of a panel of 16 well-characterized
SPs and TFPs and five surface display anchor proteins into S. cerevisiae expression cassettes. The secretion
promoting signals are validated by using five different proteins of
interest. Comparison of intracellular and secreted protein levels
reveals the optimal secretion promoting sequence for each individual
protein. Large, protein of interest-specific variations in secretion
efficiency are observed. SP sequences are also used with the five
surface display anchors, and the combination of SP and anchor protein
proves critical for efficient surface display. These observations
highlight the value of the described panel of MoClo compatible parts
to allow facile screening of SPs and TFPs and anchor proteins for
optimal secretion and/or surface display of a given protein of interest
in S. cerevisiae
A Yeast Modular Cloning (MoClo) Toolkit Expansion for Optimization of Heterologous Protein Secretion and Surface Display in Saccharomyces cerevisiae
Saccharomyces cerevisiae is an attractive
host for the expression of secreted proteins in a biotechnology context.
Unfortunately, many heterologous proteins fail to enter, or efficiently
progress through, the secretory pathway, resulting in poor yields.
Similarly, yeast surface display has become a widely used technique
in protein engineering but achieving sufficient levels of surface
expression of recombinant proteins is often challenging. Signal peptides
(SPs) and translational fusion partners (TFPs) can be used to direct
heterologous proteins through the yeast secretory pathway, however,
selection of the optimal secretion promoting sequence is largely a
process of trial and error. The yeast modular cloning (MoClo) toolkit
utilizes type IIS restriction enzymes to facilitate an efficient assembly
of expression vectors from standardized parts. We have expanded this
toolkit to enable the efficient incorporation of a panel of 16 well-characterized
SPs and TFPs and five surface display anchor proteins into S. cerevisiae expression cassettes. The secretion
promoting signals are validated by using five different proteins of
interest. Comparison of intracellular and secreted protein levels
reveals the optimal secretion promoting sequence for each individual
protein. Large, protein of interest-specific variations in secretion
efficiency are observed. SP sequences are also used with the five
surface display anchors, and the combination of SP and anchor protein
proves critical for efficient surface display. These observations
highlight the value of the described panel of MoClo compatible parts
to allow facile screening of SPs and TFPs and anchor proteins for
optimal secretion and/or surface display of a given protein of interest
in S. cerevisiae
SDSS Observations of the Milky Way vs. N-body Models: A Comparison of Stellar Distributions in the Position-Velocity-Metallicity Space
The data obtained by the recent modern sky surveys enable detailed studies of
the stellar distribution in the multi-dimensional space spanned by spatial
coordinates, velocity and metallicity, from the solar neighborhood all the way
out to the outer Milky Way halo. While these results represent exciting
observational breakthroughs, their interpretation is not simple. For example,
traditional decomposition of the thin and thick disks predicts a strong
correlation in metallicity and kinematics at 1 kpc from the Galactic
plane; however, recent SDSS--based work has demonstrated an absence of this
correlation for disk stars. Instead, the variation of the metallicity and
rotational velocity distributions can be modeled using non--Gaussian functions
that retain their shapes and only shift as the distance from the mid--plane
increases. To fully contextualize these recent observational results, a
detailed comparison with sophisticated numerical models is necessary. Modern
simulations have sufficient resolution and physical detail to study the
formation of stellar disks and spheroids over a large baseline of masses and
cosmic ages. We discuss preliminary comparisons of various observed maps and
N--body model predictions and find them encouraging. In particular, the N--body
disk models of Ro\v{s}kar et al. \cite{Roskar 2008} reproduce a change of disk
scale height reminiscent of thin/thick disk decomposition, as well as
metallicity and rotational velocity gradients, while not inducing a correlation
of the latter two quantities, in qualitative agreement with SDSS observations.Comment: Presented at the "Classification and Discovery in Large Astronomical
Surveys" meeting, Ringberg Castle, 14-17 October, 200