1,713 research outputs found
Habitat composition, sexual conflict and life history evolution in Coelopa frigida
This thesis describes an investigation into the effects of habitat composition,
principally the composition of algae in a wrack bed, on the life history of the seaweed
fly, Coelopa frigida. The mating system of C. frigida is dominated by intense sexual
conflict characterised by frequent harassment by males leading to a vigorous pre-mating
struggle. This response leads to sexual selection for large male size and sexual
dimorphism. The mating behaviour of C. frigida is affected by their environment, with
exposure to brown algae inducing harassment in males and oviposition in females.
Despite more than two decades of research into coelopid reproduction little is known
about how habitat composition alters the patterns and processes of sexual conflict.
Studies contained in this thesis consider environmental influences that both
directly and indirectly influence sexual conflict. Direct effects of the environment are
measured by conducting mating trials following culture of C. frigida on different species
of algae and by exposing males to different species of algae. This work is accompanied
by studies of larval development and adult survival on different algae. In recent years it
has been observed that the distribution of European coelopids has undergone a
northward range shift. An investigation into the current distribution of European
coelopid species and a discussion of the effects of climate change that may have caused
this change is included. Finally, the use of stable isotope analysis to determine the diet
of wild coelopids and alternative statistical methods to analyse mating trials are
described
Habitat composition, sexual conflict and life history evolution in Coelopa frigida
This thesis describes an investigation into the effects of habitat composition, principally the composition of algae in a wrack bed, on the life history of the seaweed fly, Coelopa frigida. The mating system of C. frigida is dominated by intense sexual conflict characterised by frequent harassment by males leading to a vigorous pre-mating struggle. This response leads to sexual selection for large male size and sexual dimorphism. The mating behaviour of C. frigida is affected by their environment, with exposure to brown algae inducing harassment in males and oviposition in females. Despite more than two decades of research into coelopid reproduction little is known about how habitat composition alters the patterns and processes of sexual conflict. Studies contained in this thesis consider environmental influences that both directly and indirectly influence sexual conflict. Direct effects of the environment are measured by conducting mating trials following culture of C. frigida on different species of algae and by exposing males to different species of algae. This work is accompanied by studies of larval development and adult survival on different algae. In recent years it has been observed that the distribution of European coelopids has undergone a northward range shift. An investigation into the current distribution of European coelopid species and a discussion of the effects of climate change that may have caused this change is included. Finally, the use of stable isotope analysis to determine the diet of wild coelopids and alternative statistical methods to analyse mating trials are described.EThOS - Electronic Theses Online ServiceNatural Environment Research CouncilGBUnited Kingdo
Submillimeter Follow-up of WISE-Selected Hyperluminous Galaxies
We have used the Caltech Submillimeter Observatory (CSO) to follow-up a
sample of WISE-selected, hyperluminous galaxies, so called W1W2-dropout
galaxies. This is a rare (~ 1000 all-sky) population of galaxies at high
redshift (peaks at z=2-3), that are faint or undetected by WISE at 3.4 and 4.6
um, yet are clearly detected at 12 and 22 um. The optical spectra of most of
these galaxies show significant AGN activity. We observed 14 high-redshift (z >
1.7) W1W2-dropout galaxies with SHARC-II at 350 to 850 um, with 9 detections;
and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Spitzer
follow-up of 25 targets at 3.6 and 4.5 um, as well as optical spectra of 12
targets are also presented in the paper. Combining WISE data with observations
from warm Spitzer and CSO, we constructed their mid-IR to millimeter spectral
energy distributions (SEDs). These SEDs have a consistent shape, showing
significantly higher mid-IR to submm ratios than other galaxy templates,
suggesting a hotter dust temperature. We estimate their dust temperatures to be
60-120 K using a single-temperature model. Their infrared luminosities are well
over 10^{13} Lsun. These SEDs are not well fitted with existing galaxy
templates, suggesting they are a new population with very high luminosity and
hot dust. They are likely among the most luminous galaxies in the Universe. We
argue that they are extreme cases of luminous, hot dust-obscured galaxies
(DOGs), possibly representing a short evolutionary phase during galaxy merging
and evolution. A better understanding of their long-wavelength properties needs
ALMA as well as Herschel data.Comment: Will be Published on Sep 1, 2012 by Ap
A New Population of High Redshift, Dusty Lyman-Alpha Emitters and Blobs Discovered by WISE
We report a new technique to select 1.6<z<4.6 dusty Lyman-alpha emitters
(LAEs), over a third of which are `blobs' (LABs) with emission extended on
scales of 30-100kpc. Combining data from the NASA Wide-field Infrared Survey
Explorer (WISE) mission with optical spectroscopy from the W.M. Keck telescope,
we present a color criteria that yields a 78% success rate in identifying rare,
dusty LAEs of which at least 37% are LABs. The objects have a surface density
of only ~0.1 per square degree, making them rare enough that they have been
largely missed in narrow surveys. We measured spectroscopic redshifts for 92 of
these WISE-selected, typically radio-quiet galaxies and find that the LAEs
(LABs) have a median redshift of 2.3 (2.5). The WISE photometry coupled with
data from Herschel reveals that these galaxies have extreme far-infrared
luminosities (L_IR>10^{13-14}L_sun) and warm colors, typically larger than
submillimeter-selected galaxies (SMGs) and dust-obscured galaxies (DOGs). These
traits are commonly associated with the dust being energized by intense AGN
activity. We hypothesize that the combination of spatially extended
Lyman-alpha, large amounts of warm IR-luminous dust, and rarity (implying a
short-lived phase) can be explained if the galaxies are undergoing strong
`feedback' transforming them from an extreme dusty starburst to a QSO.Comment: Submitted to ApJ Letters, 6 pages, 4 figures. Comments welcom
The GISMO Two-millimeter Deep Field in GOODS-N
We present deep continuum observations using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field in the GOODS-N field. These are the first deep field observations ever obtained at this wavelength. The 1σ sensitivity in the innermost ~4' of the 7' diameter map is ~135 μJy beam^(−1), a factor of three higher in flux/beam sensitivity than the deepest available SCUBA 850 μm observations, and almost a factor of four higher in flux/beam sensitivity than the combined MAMBO/AzTEC 1.2 mm observations of this region. Our source extraction algorithm identifies 12 sources directly, and another 3 through correlation with known sources at 1.2 mm and 850 μm. Five of the directly detected GISMO sources have counterparts in the MAMBO/AzTEC catalog, and four of those also have SCUBA counterparts. HDF850.1, one of the first blank-field detected submillimeter galaxies, is now detected at 2 mm. The median redshift of all sources with counterparts of known redshifts is med(z) = 2.91±0.94. Statistically, the detections are most likely real for five of the seven 2 mm sources without shorter wavelength counterparts, while the probability for none of them being real is negligible
Recommended from our members
Cardiac Events During Competitive, Recreational, and Daily Activities in Children and Adolescents With Long QT Syndrome
Background: The 2005 Bethesda Conference Guidelines advise patients with long QT syndrome against competitive sports. We assessed cardiac event rates during competitive and recreational sports, and daily activities among treated long QT syndrome patients. Methods and Results: Long QT syndrome patients aged ≥4 years treated with anti‐adrenergic therapy were included. Demographics included mechanism of presentation, corrected QT interval pretreatment, symptom history, medication compliance, and administration of QT‐prolonging medications. Corrected QT interval ≥550 ms or prior cardiac arrest defined high risk. Sports were categorized by cardiovascular demand per the 2005 Bethesda Conference Guidelines. Each was classified as recreational or competitive. One hundred seventy‐two patients (90; 52% female) with median age 15.2 years (interquartile range 11.4, 19.4) were included. Evaluation was performed for family history (102; 59%), incidental finding (34; 20%), and symptoms (36; 21%). Median corrected QT interval was 474 ms (interquartile range 446, 496) and 14 patients (8%) were deemed high risk. Treatment included β‐blockers (171; 99%), implantable cardioverter‐defibrillator (27; 16%), left cardiac sympathetic denervation (7; 4%), and pacemaker (3; 2%). Sports participation was recreational (66; 38%) or competitive (106; 62%), with 92 (53%) exercising against the Bethesda Conference Guidelines. There were no cardiac events in competitive athletes and no deaths. There were 13 cardiac events in 9 previously symptomatic patients during either recreational exercise or activities of daily life. Conclusions: In this cohort of appropriately managed children with long QT syndrome, cardiac event rates were low and occurred during recreational but not competitive activities. This study further supports the need for increased assessment of arrhythmia risk during exercise in this patient population
A New Era in Extragalactic Background Light Measurements: The Cosmic History of Accretion, Nucleosynthesis and Reionization
(Brief Summary) What is the total radiative content of the Universe since the
epoch of recombination? The extragalactic background light (EBL) spectrum
captures the redshifted energy released from the first stellar objects,
protogalaxies, and galaxies throughout cosmic history. Yet, we have not
determined the brightness of the extragalactic sky from UV/optical to
far-infrared wavelengths with sufficient accuracy to establish the radiative
content of the Universe to better than an order of magnitude. Among many
science topics, an accurate measurement of the EBL spectrum from optical to
far-IR wavelengths, will address: What is the total energy released by stellar
nucleosynthesis over cosmic history? Was significant energy released by
non-stellar processes? Is there a diffuse component to the EBL anywhere from
optical to sub-millimeter? When did first stars appear and how luminous was the
reionization epoch? Absolute optical to mid-IR EBL spectrum to an
astrophysically interesting accuracy can be established by wide field imagingat
a distance of 5 AU or above the ecliptic plane where the zodiacal foreground is
reduced by more than two orders of magnitude.Comment: 7 pages; Science White Paper for the US Astro 2010-2020 Decadal
Survey. If interested in further community-wide efforts on this topic please
contact the first autho
The Primordial Inflation Polarization Explorer (PIPER): Current Status and Performance of the First Flight
The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne instrument optimized to measure the polarization of the CMB at large angular scales. It will map 85% of the sky over a series of conventional balloon flights from the Northern and Southern hemispheres, measuring the B-mode polarization power spectrumover a range of multipoles from 2-300 covering both the reionization bump and the recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0.007. PIPER will observe in four frequency bands centered at 200, 270, 350, and 600 GHz to characterize dust foregrounds. The instrument has background-limited sensitivity provided by fully cryogenic (1.7 K) optics focusing the sky signal onto kilo-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 100 mK. Polarization sensitivity and systematiccontrol are provided by front-end Variable-delay Polarization Modulators (VPMs). PIPER had its engineering flight in October 2017 from Fort Sumner, New Mexico. This papers outlines the major components in the PIPER system discussing the conceptual design as well as specific choices made for PIPER. We also report on the results of the engineering flight, looking at the functionality of the payload systems, particularly VPM, as well as pointing out areas of improvement
Observing the Evolution of the Universe
How did the universe evolve? The fine angular scale (l>1000) temperature and
polarization anisotropies in the CMB are a Rosetta stone for understanding the
evolution of the universe. Through detailed measurements one may address
everything from the physics of the birth of the universe to the history of star
formation and the process by which galaxies formed. One may in addition track
the evolution of the dark energy and discover the net neutrino mass.
We are at the dawn of a new era in which hundreds of square degrees of sky
can be mapped with arcminute resolution and sensitivities measured in
microKelvin. Acquiring these data requires the use of special purpose
telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and
the South Pole Telescope (SPT). These new telescopes are outfitted with a new
generation of custom mm-wave kilo-pixel arrays. Additional instruments are in
the planning stages.Comment: Science White Paper submitted to the US Astro2010 Decadal Survey.
Full list of 177 author available at http://cmbpol.uchicago.ed
- …