2,315 research outputs found
Lensing reconstruction from line intensity maps: the impact of gravitational nonlinearity
We investigate the detection prospects for gravitational lensing of
three-dimensional maps from upcoming line intensity surveys, focusing in
particular on the impact of gravitational nonlinearities on standard quadratic
lensing estimators. Using perturbation theory, we show that these
nonlinearities can provide a significant contaminant to lensing reconstruction,
even for observations at reionization-era redshifts. However, we show how this
contamination can be mitigated with the use of a "bias-hardened" estimator.
Along the way, we present an estimator for reconstructing long-wavelength
density modes, in the spirit of the "tidal reconstruction" technique that has
been proposed elsewhere, and discuss the dominant biases on this estimator.
After applying bias-hardening, we find that a detection of the lensing
potential power spectrum will still be challenging for the first phase of
SKA-Low, CHIME, and HIRAX, with gravitational nonlinearities decreasing the
signal to noise by a factor of a few compared to forecasts that ignore these
effects. On the other hand, cross-correlations between lensing and galaxy
clustering or cosmic shear from a large photometric survey look promising,
provided that systematics can be sufficiently controlled. We reach similar
conclusions for a single-dish survey inspired by CII measurements planned for
CCAT-prime, suggesting that lensing is an interesting science target not just
for 21cm surveys, but also for intensity maps of other lines.Comment: 40+18 pages, 13 figures, 5 tables. v2: JCAP published version, with
typos fixed and clarifications adde
Increased amino acid turnover and myofibrillar protein breakdown in advanced cancer are associated with muscle weakness and impaired physical function
Muscle wasting in cancer negatively affects physical function and quality of life. This study investigates amino acid metabolism and the association with muscle mass and function in patients with cancer.In 16 patients with advanced cancer undergoing chemotherapy and 16 healthy controls, we administered an intravenous pulse and prime of stable amino acid tracers. We took blood samples to measure the Rate of appearance (Ra), whole body production (WBP), clearance (Cl), and post absorptive whole body net protein breakdown (WBnetPB). Plasma amino acid concentrations and enrichments were analysed by LC-MS/MS. We assessed muscle mass, handgrip/leg/respiratory muscle strength and reported physical activity, quality of life, and physical function.Muscle strength was lower in cancer patients than in healthy controls. Total and limb muscle mass, reported physical activity and WBnetPB were comparable. WBP and Cl of tau-methylhistidine, leucine, glutamine and taurine were higher in cancer patients as well as glycine Cl. Amino acid metabolism was correlated with low muscle mass, strength, physical function and quality of life.Myofibrillar protein breakdown and production of amino acids involved in muscle contractility are up regulated in patients with cancer undergoing chemotherapy and related to muscle weakness and reduced physical outcomes
CMB Lensing Power Spectrum Biases from Galaxies and Clusters using High-angular Resolution Temperature Maps
The lensing power spectrum from cosmic microwave background (CMB) temperature
maps will be measured with unprecedented precision with upcoming experiments,
including upgrades to ACT and SPT. Achieving significant improvements in
cosmological parameter constraints, such as percent level errors on sigma_8 and
an uncertainty on the total neutrino mass of approximately 50 meV, requires
percent level measurements of the CMB lensing power. This necessitates tight
control of systematic biases. We study several types of biases to the
temperature-based lensing reconstruction signal from foreground sources such as
radio and infrared galaxies and the thermal Sunyaev-Zel'dovich effect from
galaxy clusters. These foregrounds bias the CMB lensing signal due to their
non-Gaussian nature. Using simulations as well as some analytical models we
find that these sources can substantially impact the measured signal if left
untreated. However, these biases can be brought to the percent level if one
masks galaxies with fluxes at 150 GHz above 1 mJy and galaxy clusters with
masses above M_vir = 10^14 M_sun. To achieve such percent level bias, we find
that only modes up to a maximum multipole of l_max ~ 2500 should be included in
the lensing reconstruction. We also discuss ways to minimize additional bias
induced by such aggressive foreground masking by, for example, exploring a
two-step masking and in-painting algorithm.Comment: 14 pages, 14 figures, to be submitted to Ap
High Pressure X-Ray Diffraction Study of UMn2Ge2
Uranium manganese germanide, UMn2Ge2, crystallizes in body-centered
tetragonal ThCr2Si2 structure with space group I4/mmm, a = 3.993A and c =
10.809A under ambient conditions. Energy dispersive X-ray diffraction was used
to study the compression behaviour of UMn2Ge2 in a diamond anvil cell. The
sample was studied up to static pressure of 26 GPa and a reversible structural
phase transition was observed at a pressure of ~ 16.1 GPa. Unit cell parameters
were determined up to 12.4 GPa and the calculated cell volumes were found to be
well reproduced by a Murnaghan equation of state with K0 = 73.5 GPa and K' =
11.4. The structure of the high pressure phase above 16.0 GPa is quite
complicated with very broad lines and could not be unambiguously determined
with the available instrument resolution
Minimizing gravitational lensing contributions to the primordial bispectrum covariance
The next generation of ground-based cosmic microwave background (CMB) experiments aim to measure temperature and polarization fluctuations up to ℓmax≈5000 over half of the sky. Combined with Planck data on large scales, this will provide improved constraints on primordial non-Gaussianity. However, the impressive resolution of these experiments will come at a price. Besides signal confusion from galactic foregrounds, extragalactic foregrounds, and late-time gravitational effects, gravitational lensing will introduce large non-Gaussianity that can become the leading contribution to the bispectrum covariance through the connected four-point function. Here, we compute this effect analytically for the first time on the full sky for both temperature and polarization. We compare our analytical results with those obtained directly from map-based simulations of the CMB sky for several levels of instrumental noise. Of the standard shapes considered in the literature, the local shape is most affected, resulting in a 35% increase of the estimator standard deviation for an experiment such as the Simons Observatory (SO) and a 110% increase for a cosmic-variance limited experiment, including both temperature and polarization modes up to ℓmax=3800. Because of the nature of the lensing four-point function, the impact on other shapes is reduced while still non-negligible for the orthogonal shape. Two possible avenues to reduce the non-Gaussian contribution to the covariance are proposed: First by marginalizing over lensing contributions, such as the Integrated Sachs Wolfe (ISW)-lensing three-point function in temperature, and second by delensing the CMB. We show the latter method can remove almost all extra covariance, reducing the effect to below <5% for local bispectra. At the same time, delensing would remove signal biases from secondaries induced by lensing, such as ISW lensing. We aim to apply both techniques directly to the forthcoming SO data when searching for primordial non-Gaussianity
Positive or Preventive?
This book adresses an important issue in historical demography - the differences between reproduction in low pressure and high pressure demographic regimes. The existence of such differences was first noted in 1789 by Thomas Malthus when he contrasted the low pressure European regimes with the high pressure regimes found in the less civilized parts of the world, most notably China and Japan. This contrast, long taken as fundamental by historical demographers, has recently been challenged by authors who argue that it should be discarded as Malthusian mythology. The papers included here evaluate the received and revisionist views by comparing reproduction in a high pressure regime - Taiwan during the Japanese occupation - and a low pressure regime - the Netherlands in the years 1830-1920. The papers examine the impact of infant mortality, social class, ethnic identity, illegitimacy, form of marriage, and rural vs. urban settings. Reality or mythology?, that is the question
Measurement of the temperature of an ultracold ion source using time-dependent electric fields
We report on a measurement of the characteristic temperature of an ultracold
rubidium ion source, in which a cloud of laser-cooled atoms is converted to
ions by photo-ionization. Extracted ion pulses are focused on a detector with a
pulsed-field technique. The resulting experimental spot sizes are compared to
particle-tracking simulations, from which a source temperature
mK and the corresponding transversal reduced emittance m rad are determined. We find that this result is
likely limited by space charge forces even though the average number of ions
per bunch is 0.022.Comment: 8 pages, 11 figure
Compact Laser Communication Terminal Architecture and In-Orbit Demonstration
Satellites are generating more data than ever due to more demanding payloads, although communications Down To Earth (DTE) have not experienced the same growth in data rates. Compact Laser Communication Terminals are a promising technology that will increase bandwidths (10 Gbit+) and pave the way for larger data volumes to be transmitted which will increase the relevance of small and CubeSats in space data as service offerings. The in-orbit demonstrator is targeting a downlink data rate of 1 Gbit/s with a range of up to 1000km. A downlink wavelength of 1545nm is used while 1590nm is used for the ground station beacon. PRBS23 sequences will be transmitted from the in-orbit terminal to a ground station in the Netherlands. During in-orbit experimentation, attempts will be made to acquire payload data from other onboard payloads and to forward this data down to earth. This will provide valuable insight into possible future enhancements.
The goal is to use the lessons learned from the in-orbit demonstration and results to drive the development of future iterations of the terminal. Lessons learned during the development phase, market feedback and test results are already being used to shape the architecture and design of the system. The following learnings are anticipated: robust fast data storage does add value; higher down and upload speeds are required; throughput enhancement using adjustable data rates will be worth the investment and enhancing error correction allows for more efficient transfers
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