1,879 research outputs found
The Great Observatories Origins Deep Survey
The Great Observatories Origins Deep Survey (GOODS) is designed to gather the
best and deepest multiwavelength data for studying the formation and evolution
of galaxies and active galactic nuclei, the distribution of dark and luminous
matter at high redshift, the cosmological parameters from distant supernovae,
and the extragalactic background light. The program uses the most powerful
space- and ground-based telescopes to cover two fields, each 10'x16', centered
on the Hubble Deep Field North and the Chandra Deep Field South, already the
sites of extensive observations from X-ray through radio wavelengths. GOODS
incorporates 3.6-24 micron observations from a SIRTF Legacy Program, four-band
ACS imaging from an HST Treasury Program, and extensive new ground-based
imaging and spectroscopy. GOODS data products will be made available on a rapid
time-scale, enabling community research on a wide variety of topics. Here we
describe the project, emphasizing its application for studying the mass
assembly history of galaxies.Comment: 8 pages, 2 figures, to appear in the proceedings of the ESO/USM
Workshop "The Mass of Galaxies at Low and High Redshift" (Venice, Italy,
October 2001), eds. R. Bender and A. Renzin
IRAC Deep Survey of COSMOS
Over the last four years, we have developed the COSMOS survey field with complete multi-wavelength coverage from radio to X-ray, including a total of 600 hours of Spitzer Legacy time (166 hours IRAC, 460 hours MIPS). Here we propose to deepen the IRAC 3.6 µm and 4.5 µm coverage with 3000 hours over 2.3 deg^2 area included in deep Subaru imaging. This extended mission deep survey will increase the sensitivity by a factor of 3–5. The most important impact will be that the COSMOS survey will then provide extremely sensitive photometric redshifts and stellar mass estimates for approximately a million galaxies out to z~6. We expect these data to detect approximately 1000 objects at z = 6 to 10. The data will also provide excellent temporal coverage for variability studies on timescales from days to the length of the extended mission
Probing Outflows in z= 1~2 Galaxies through FeII/FeII* Multiplets
We report on a study of the 2300-2600\AA FeII/FeII* multiplets in the rest-UV
spectra of star-forming galaxies at 1.0<z<2.6 as probes of galactic-scale
outflows. We extracted a mass-limited sample of 97 galaxies at z~1.0-2.6 from
ultra-deep spectra obtained during the GMASS spetroscopic survey in the GOODS
South field with the VLT and FORS2. We obtain robust measures of the rest
equivalent width of the FeII absorption lines down to a limit of W_r>1.5 \AA
and of the FeII* emission lines to W_r>0.5 \AA. Whenever we can measure the
systemic redshift of the galaxies from the [OII] emission line, we find that
both the FeII and MgII absorption lines are blueshifted, indicative that both
species trace gaseous outflows. We also find, however, that the FeII gas has
generally lower outflow velocity relative to that of MgII. We investigate the
variation of FeII line profiles as a function of the radiative transfer
properties of the lines, and find that transitions with higher oscillator
strengths are more blueshifted in terms of both line centroids and line wings.
We discuss the possibility that FeII lines are suppressed by stellar
absorptions. The lower velocities of the FeII lines relative to the MgII
doublet, as well as the absence of spatially extended FeII* emission in 2D
stacked spectra, suggest that most clouds responsible for the FeII absorption
lie close (3~4 kpc) to the disks of galaxies. We show that the FeII/FeII*
multiplets offer unique probes of the kinematic structure of galactic outflows.Comment: 53 pages, 22 Figures, accepted for publication in ApJ, revised
according to referee comment
Proteomanalyse von Pflanzen
Titelseite
Inhaltsverzeichnis
1. Einleitung 1
2\. Methoden 13
3\. Ergebnisse 46
4\. Diskussion 99
5\. Zusammenfassung 121
6\. Summary 122
7\. Abkuerzungen 123
8\. Literaturverzeichnis 124
9\. Eigene Veroeffentlichungen 138
10\. Danksagung 140Within the course of this PhD thesis twodimensional gelelectrophoresis and
MALDI-TOF-MS based methods have been evaluated and developed to fulfil the aim
of large scale plant proteomics. Particular attention was paid to the
optimisation of proteinextraction, proteinseparation and proteinstaining. In
this context a new fractionation based proteinextraction method which gave
rise to an 300 % increased display of proteinspots on 2-DE gels could be
established. On the basis of the developed techniques we were able to
establish a set of 2-DE standardpatterns from 8 different Arabidopsis thaliana
tissues. Apart from the optimisation of 2-DE techniques an improved, robust
and automated MALDI sample preparation system could be established. The set up
of these methods allows the analysis and handling of more than 1000
proteinspots from 2-DE gels per day. In a following step the combination of
the 2-DE-and the MALDI protocols will be employed for the large scale
identification of a vast portion of the Arabidopsis thaliana proteome. As a
primary step it was possible in a set of proof of principle experiments to
identify 681 proteinspots from two different Arabidopsis thaliana leaf
fraction 2-DE gels. Further we identified 352 proteinspots from an Arabidopsis
thaliana silique 2-DE gel. In total the number of these preliminary identified
proteins exceeds by far the number of previous published 2-DE proteomic data
from Arabidopsis thaliana. In a second proof of principle experiment it was
possible to show the increased separation capabilities of 2-DE gels. In this
example the identification of differentially expressed proteins from water
starved cucumber plants was achieved. This experiment clearly showed the need
of two-dimensional separation of proteins from complex mixtures to display
differentially expressed proteins, since one-dimensional protein separation is
not sufficient to fulfil this task. In a last example the combination of
tissue prefractionation techniques with 2-DE and MALDI-MS was used to identify
an Arabidopsis thaliana subproteome. In this case the purification of
cytosolic 80S ribosomal proteins was achieved by sucrose gradient density
centrifugation of Arabidopsis thaliana leaf tissue. In this experiment it was
possible to identify a large part (70 %) of the expected protein components of
plants cytosolic ribosome from a single gel in a single round of
identification. In total a number of 224 proteinspots could be identified from
this ribosomal sample.Im Rahmen der vorliegenden Arbeit wurden Techniken ebenso wie Methoden
evaluiert und entwickelt, die basierend auf der Verwendung von
zweidimensionaler Gelelektrophorese und MALDI-TOF-MS Proteomanalysen von
pflanzlichen Geweben ermöglichen. Hierbei wurden zunächst optimierte Methoden
für die Proteinextraktion, Proteintrennung und die Proteinfärbung für die 2-DE
erarbeitet. So konnte z. B. eine neue fraktionierte
Gesamtproteinextraktionsmethode für Pflanzengewebe entwickelt werden, die eine
bis zu 300 % verbesserte Ausbeute an Proteinspots auf 2-DE-Gelen im Vergleich
zu Standardextraktionsmethoden zulässt. Diese optimierten Methoden wurden in
einem weiterführenden Schritt für die Herstellung von 2-DE-Standardmustern aus
8 unterschiedlichen Arabidopsis thaliana-Geweben eingesetzt. Neben der
Methodenentwicklung im 2-DE-Bereich wurden im Bereich der MALDI-
Probenpräparation und der MALDI-Analyse stabile und automatisierte Protokolle
für die Identifikation von 2-DE-Gel-getrennten Proteinen etabliert. Diese
Protokolle ermöglichen es, mehr als 1000 Proteinspots pro Tag
massenspektrometrisch zu analysieren. Um die reelle Anwendbarkeit und
Tauglichkeit der entwickelten Methoden zu dokumentieren, wurden anhand dreier
charakteristischer pflanzenspezifischer Fragestellungen Beispielexperimente
durchgeführt. So ließen sich in einem ersten Ansatz 681 Proteinspots aus 2
unterschiedlichen Arabidopsis thaliana-Blattproteinextrakten und 352
Proteinspots aus einem Arabidopsis thaliana-Schotenproteinextrakt
identifizieren. Die hierbei identifizierten Proteine, die aus nur 3 2-DE-Gelen
stammten, übersteigen in ihrer Summe bereits alle bis dato publizierten Daten
im Bereich der Arabidopsis thaliana-2-DE-basierten Proteomforschung. In einem
zweiten Anwendungsexperiment wurden differentiell regulierte Phloemproteine
aus trockengestressten Gurkenpflanzen in 2-DE-Gelen dargestellt und
identifiziert. Hierbei zeigte sich, dass diese Art der differentiellen Analyse
komplexerer Proteinmischungen das Auflösungsvermögen von herkömmlichen
eindimensionalen Trennsystemen übersteigt und somit fast ausschließlich
mittels zweidimensionalen Trennsystemen durchgeführt werden sollte. In einem
letzten Anwendungsbeispiel, dessen Fokus auf der Analyse des cytosolischen 80S
Ribosoms aus Arabidopsis thaliana-Blättern lag, konnte durch die Kombination
einer Gewebsvorfraktionierung und der 2-DE ein Großteil (70 %) der bekannten
Komponenten des cytosolischen Ribosoms bestimmt werden. Insgesamt ließen sich
hierbei 224 Proteinspots aus einem einzigen 2-DE-Gel identifizieren
High-energy Astrophysics and the Virtual Observatory
The Virtual Observatory (VO) will revolutionise the way we do Astronomy by
allowing easy access to all astronomical data and by making the handling and
analysis of datasets at various locations across the globe much simpler and
faster. I report here on the need for the VO and its status in Europe,
concentrating on the recently started EURO-VO project, and then give two
specific applications of VO tools to high-energy astrophysics.Comment: 12 pages, 3 figures, invited talk at the Workshop ``Multifrequency
Behaviour of High Energy Cosmic Sources'', Vulcano, Italy, May 2005, F.
Giovannelli et al., in pres
Galaxy Clustering at z~3
Galaxies at very high redshift (z~3 or greater) are now accessible to
wholesale observation, making possible for the first time a robust statistical
assessment of their spatial distribution at lookback times approaching ~90% of
the age of the Universe. This paper summarizes recent progress in understanding
the nature of these early galaxies, concentrating in particular on the
clustering properties of photometrically selected ``Lyman break'' galaxies.
Direct comparison of the data to predictions and physical insights provided by
galaxy and structure formation models is particularly straightforward at these
early epochs, and results in critical tests of the ``biased'', hierarchical
galaxy formation paradigm.Comment: Presented at Royal Society Discussion Meeting, March 1998, "Large
Scale Structure in the Universe", 14 pages LaTeX, 7 ps figures, uses
rspublic.sty (included
Reconstructing the Assembly of Massive Galaxies. I: The Importance of the Progenitor Effect in the Observed Properties of Quiescent Galaxies at
We study the relationship between the morphology and star formation history
(SFH) of 361 quiescent galaxies (QGs) at redshift , with stellar mass , selected with
the UVJ technique. Taking advantage of panchromatic photometry covering the
rest-frame UV-to-NIR spectral range ( bands), we reconstruct the
non-parametric SFH of the galaxies with the fully Bayesian SED fitting code
Prospector. We find that the half-light radius , observed at ,
depends on the formation redshift of the galaxies, , and that this
relationship depends on stellar mass. At , the relationship is
consistent with , in line with the expectation
that the galaxies' central density depends on the cosmic density at the time of
their formation, i.e. the "progenitor effect". At , the
relationship between and flattens, suggesting that mergers
become increasingly important for the size growth of more massive galaxies
after they quenched. We also find that the relationship between and
galaxy compactness similarly depends on stellar mass. While no clear trend is
observed for QGs with , lower-mass QGs that formed earlier, i.e.
with larger , have larger central stellar mass surface densities,
both within the () and central 1 kpc (), and
also larger , the fractional mass within the central 1 kpc. These
trends between and compactness, however, essentially disappear, if
the progenitor effect is removed by normalizing the stellar density with the
cosmic density at . Our findings highlight the importance of
reconstructing the SFH of galaxies before attempting to infer their intrinsic
structural evolution.Comment: 34 pages, 27 figures; Submitted to ApJ; Comments welcom
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