1,084 research outputs found
Horn Studio Recital
Horn Studio RecitalDaniel Stipe & Hope Armstrong-Erb, pianoTuesday, November 5, 2019 at 7pmSonia Vlahcevic Concert HallSingleton Center for the Performing Arts922 Park VaenueRichmond, Virgini
2D Kinematics and Physical Properties of z~3 Star-Forming Galaxies
We present results from a study of the kinematic structure of star-forming
galaxies at redshift z~3 selected in the VVDS, using integral-field
spectroscopy of rest-frame optical nebular emission lines, in combination with
rest-frame UV spectroscopy, ground-based optical/near-IR and Spitzer
photometry. We also constrain the underlying stellar populations to address the
evolutionary status of these galaxies. We infer the kinematic properties of
four galaxies: VVDS-20298666, VVDS-020297772, VVDS-20463884 and VVDS-20335183
with redshifts z = 3.2917, 3.2878, 3.2776, and 3.7062, respectively. While
VVDS-20463884 presents an irregular velocity field with a peak in the local
velocity dispersion of the galaxy shifted from the centre of the galaxy,
VVDS-20298666 has a well-resolved gradient in velocity over a distance of ~4.5
kpc with a peak-to-peak amplitude of v = 91 km/s . We discovered that the
nearby galaxy, VVDS-020297772 (which shows traces of AGN activity), is in fact
a companion at a similar redshift with a projected separated of 12 kpc. In
contrast, the velocity field of VVDS-020335183 seems more consistent with a
merger on a rotating disk. However, all of the objects have a high local
velocity dispersion (sigma ~ 60-70 km/s), which gives v/sigma < 1. It is
unlikely that these galaxies are dynamically cold rotating disk of ionized gas.Comment: 14 pages and 16 figure
Consumption-Based Conservation Targeting: Linking Biodiversity Loss to Upstream Demand through a Global Wildlife Footprint.
Although most conservation efforts address the direct, local causes of biodiversity loss, effective long-term conservation will require complementary efforts to reduce the upstream economic pressures, such as demands for food and forest products, which ultimately drive these downstream losses. Here, we present a wildlife footprint analysis that links global losses of wild birds to consumer purchases across 57 economic sectors in 129 regions. The United States, India, China, and Brazil have the largest regional wildlife footprints, while per-person footprints are highest in Mongolia, Australia, Botswana, and the United Arab Emirates. A US$100 purchase of bovine meat or rice products occupies approximately 0.1 km2 of wild bird ranges, displacing 1-2 individual birds, for 1 year. Globally significant importer regions, including Japan, the United Kingdom, Germany, Italy, and France, have large footprints that drive wildlife losses elsewhere in the world and represent important targets for consumption-focused conservation attention
Metallicity Gradient of a Lensed Face-on Spiral Galaxy at Redshift 1.49
We present the first metallicity gradient measurement for a grand-design
face-on spiral galaxy at z~1.5. This galaxy has been magnified by a factor of
22 by a massive, X-ray luminous galaxy cluster MACS\,J1149.5+2223 at
z=0.544. Using the Laser Guide Star Adaptive Optics aided integral field
spectrograph OSIRIS on KECK II, we target the Halpha emission and achieve a
spatial resolution of 0.1", corresponding to a source plane resolution of 170
pc. The galaxy has well-developed spiral arms and the nebular emission line
dynamics clearly indicate a rotationally supported disk with V_{rot}/\sigma~4.
The best-fit disk velocity field model yields a maximum rotation of V_{rot}
sin{i}=15015 km s^{-1}, and a dynamical mass of
M_{dyn}=1.3\pm10^{\circ}\pm^{-1}$, significantly steeper than the gradient of late-type or early-type
galaxies in the local universe. If representative of disk galaxies at z~1.5,
our results support an "inside-out" disk formation scenario in which early
infall/collapse in the galaxy center builds a chemically enriched nucleus,
followed by slow enrichment of the disk over the next 9 Gyr.Comment: 13page, 4 figures, ApJL in press (updated version after proof
Strategies for feeding the world more sustainably with organic agriculture
The authors are grateful for the inputs from Caterina Batello, Jan Breithaupt, Carlo Cafiero, Marianna Campeanu, Reto Cumani, Rich Conant, Piero Conforti, Marie-Aude Even, Karen Franken, Andreas Gattinger, Pierre Gerber, Frank Hayer, Jippe Hoogeven, Stefan Hörtenhuber, Mathilde Iweins, John Lantham, Robert Mayo, Eric Meili, Soren Moller, Jamie Morrison, Alexander MĂŒller, Noemi Nemes, Monica Petri, Tim Robinson, Nicolas Sagoff, Henning Steinfeld, Francesco Tubiello, Helga Willer, and thank Robert Home for checking the language. KHE gratefully acknowledges funding from ERC-2010-Stg-263522 (LUISE). The input of PS contributes to the DEVIL project (NE/M021327/1), funded under the Belmont Forum / FACCE-JPI. This paper contributes to the Global Land Project (www.globallandproject.org). The authors acknowledge funding for open access publication by the Institute of Environmental Decisions, Federal Institutes of Technology, Zurich.Peer reviewedPublisher PD
The Emission Line Properties of Gravitationally-lensed 1.5 < z < 5 Galaxies
We present and analyse near-infrared spectroscopy for a sample of 28
gravitationally- lensed star-forming galaxies in the redshift range 1.5 < z <
5, observed mostly with the Keck II telescope. With typical magnifications of
~1.5-4 magnitudes, our survey provides a valuable census of star formation
rates, gas-phase metallicities and dynamical masses for a representative sample
of low luminosity galaxies seen at a formative period in cosmic history. We
find less evolution in the mass-metallicity relation compared to earlier work
that focused on more luminous systems with z - 2-3, especially in the low mass
(- 10^9 Msol) where our sample is - 0.25 dex more metal-rich. We interpret this
offset as a result of the lower star formation rates (typically a factor of -10
lower) for a given stellar mass in our sub-luminous systems. Taking this effect
into account, we conclude our objects are consistent with a fundamental
metallicity relation recently proposed from unlensed observations.Comment: 22 pages, 12 figures, MNRAS, version including proof correction
The role of laccase in prostaglandin production by Cryptococcus neoformans
Recently, it has been demonstrated that the opportunistic fungal pathogen Cryptococcus neoformans can synthesize authentic immunomodulatory prostaglandins. The mechanism by which this takes place is unclear as there is no cyclooxygenase homologue in the cryptococcal genome. In this study, we show that cryptococcal production of both PGE 2 and PGF 2α can be chemically inhibited by caffeic acid, resveratrol and nordihydroguaiaretic acid. These polyphenolic molecules are frequently used as inhibitors of lipoxygenase enzymes; however, blast searches of the cryptococcal genome were unable to identify any homologues of mammalian, plant or fungal lipoxygenases. Next we investigated cryptococcal laccase, an enzyme known to bind polyphenols, and found that either antibody depletion or genetic deletion of the primary cryptococcal laccase ( lac1 Ύ) resulted in a loss of cryptococcal prostaglandin production. To determine how laccase is involved, we tested recombinant laccase activity on the prostaglandin precursors, arachidonic acid (AA), PGG 2 and PGH 2 . Using mass spectroscopy we determined that recombinant Lac1 does not modify AA or PGH 2 , but does have a marked activity toward PGG 2 converting it to PGE 2 and 15-keto-PGE 2 . These data demonstrate a critical role for laccase in cryptococcal prostaglandin production, and provides insight into a new and unique fungal prostaglandin pathway.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73041/1/j.1365-2958.2008.06245.x.pd
Bioenergy: how much can we expect for 2050?
Estimates of global primary bioenergy potentials in the literature span almost three orders of magnitude. We narrow that range by discussing biophysical constraints on bioenergy potentials resulting from plant growth (NPP) and its current human use. In the last 30 years, terrestrial NPP was almost constant near 54 PgC yrâ1, despite massive efforts to increase yields in agriculture and forestry. The global human appropriation of terrestrial plant production has doubled in the last century. We estimate the maximum physical potential of the world\u27s total land area outside croplands, infrastructure, wilderness and denser forests to deliver bioenergy at approximately 190 EJ yrâ1. These pasture lands, sparser woodlands, savannas and tundras are already used heavily for grazing and store abundant carbon; they would have to be entirely converted to bioenergy and intensive forage production to provide that amount of energy. Such a high level of bioenergy supply would roughly double the global human biomass harvest, with far-reaching effects on biodiversity, ecosystems and food supply. Identifying sustainable levels of bioenergy and finding ways to integrate bioenergy with food supply and ecological conservation goals remains a huge and pressing scientific challenge
The galaxy stellar mass-star formation rate relation: Evidence for an evolving stellar initial mass function?
The evolution of the galaxy stellar mass--star formation rate relationship
(M*-SFR) provides key constraints on the stellar mass assembly histories of
galaxies. For star-forming galaxies, M*-SFR is observed to be fairly tight with
a slope close to unity from z~0-2. Simulations of galaxy formation reproduce
these trends owing to the generic dominance of smooth and steady cold accretion
in these systems. In contrast, the amplitude of the M*-SFR relation evolves
markedly differently than in models. Stated in terms of a star formation
activity parameter alpha=(M*/SFR)/(t_H-1 Gyr), models predict a constant
alpha~1 out to redshifts z=4+, while the observed M*-SFR relation indicates
that alpha increases by X3 from z~2 until today. The low alpha at high-z not
only conflicts with models, but is also difficult to reconcile with other
observations of high-z galaxies. Systematic biases could significantly affect
measurements of M* and SFR, but detailed considerations suggest that none are
obvious candidates to reconcile the discrepancy. A speculative solution is
considered in which the stellar initial mass function (IMF) evolves towards
more high-mass star formation at earlier epochs. Following Larson, a model is
investigated in which the characteristic mass Mhat where the IMF turns over
increases with redshift. The observed and predicted M*-SFR evolution may be
brought into agreement if Mhat=0.5(1+z)^2 Mo out to z~2. Such evolution broadly
matches recent observations of cosmic stellar mass growth, and the resulting
z=0 cumulative IMF is similar to the paunchy IMF favored by Fardal et al to
reconcile the observed cosmic star formation history with present-day fossil
light measures. [abridged]Comment: 14 pages, MNRAS, accepted version. Significant expansion of
discussion; includes comparisons to new observation
Excess AGN Activity in the z=2.30 Protocluster in HS 1700+64
We present the results of spectroscopic, narrow-band and X-ray observations
of a z=2.30 protocluster in the field of the QSO HS 1700+643. Using a sample of
BX/MD galaxies, which are selected to be at z~2.2-2.7 by their rest-frame
ultraviolet colours, we find that there are 5 protocluster AGN which have been
identified by characteristic emission-lines in their optical/near-IR spectra;
this represents an enhancement over the field significant at ~98.5 per cent
confidence. Using a ~200 ks Chandra/ACIS-I observation of this field we detect
a total of 161 X-ray point sources to a Poissonian false-probability limit of
4x10^{-6} and identify 8 of these with BX/MD galaxies. Two of these are
spectroscopically confirmed protocluster members and are also classified as
emission-line AGN. When compared to a similarly selected field sample the
analysis indicates this is also evidence for an enhancement of X-ray selected
BX/MD AGN over the field, significant at ~99 per cent confidence. Deep Lya
narrow-band imaging reveals that a total of 4/123 Lya emitters (LAEs) are found
to be associated with X-ray sources, with two of these confirmed protocluster
members and one highly likely member. We do not find a significant enhancement
of AGN activity in this LAE sample over that of the field (result significant
at only 87 per cent confidence). The X-ray emitting AGN fractions for the BX/MD
and LAE samples are found to be 6.9_{-4.4}^{+9.2} and 2.9_{-1.6}^{+2.9} per
cent, respectively, for protocluster AGN with L_{2-10 keV}>4.6x10^{43} erg
s^{-1} at z=2.30. These findings are similar to results from the z=3.09
protocluster in the SSA 22 field found by Lehmer et al. (2009), in that both
suggest AGN activity is favoured in dense environments at z>2.Comment: 8 pages, 2 figures. Accepted for publication in MNRAS
- âŠ