366 research outputs found
Crosstalk effects in microwave SQUID multiplexed TES bolometer readout
Transition-edge sensor (TES) bolometers are broadly used for
background-limited astrophysical measurements from the far-infrared to
mm-waves. Many planned future instruments require increasingly large detector
arrays, but their scalability is limited by their cryogenic readout
electronics. Microwave SQUID multiplexing offers a highly capable scaling
solution through the use of inherently broadband circuitry, enabling readout of
hundreds to thousands of channels per microwave line. As with any multiplexing
technique, the channelization mechanism gives rise to electrical crosstalk
which must be understood and controlled so as to not degrade the instrument
sensitivity. Here, we explore implications relevant for TES bolometer array
applications, focusing in particular on upcoming mm-wave observatories such as
the Simons Observatory and AliCPT. We model the relative contributions of the
various underlying crosstalk mechanisms, evaluate the difference between
fixed-tone and tone-tracking readout systems, and discuss ways in which
crosstalk nonlinearity will complicate on-sky measurements.Comment: Submitted to the Journal of Low Temperature Physic
Extent of alteration, paleomagnetic history, and infrared spectral properties of the Tarda ungrouped carbonaceous chondrite
Tarda is an ungrouped, hydrated carbonaceous chondrite (C2âung) that was seen to fall in Morocco in 2020. Early studies showed that Tarda chemically resembles another ungrouped chondrite, Tagish Lake (C2âung), which has previously been linked to the dark Dâtype asteroids. Samples of Dâtype asteroids provide an important opportunity to investigate primitive conditions in the outer solar system. We show that Tarda contains few intact chondrules and refractory inclusions and that its composition is dominated by secondary Mgârich phyllosilicates (>70 vol%), carbonates, oxides, and Feâsulfides that formed during extensive waterârock reactions. Quantitative assessment of firstâorder reversal curve (FORC) diagrams shows that Tarda's magnetic mineralogy (i.e., framboidal magnetite) is comparable to that of the CI chondrites and differs notably from that of most CM chondrites. These traits support a common formation process for magnetite in Tarda and the CI chondrites. Furthermore, Tarda's preâterrestrial paleomagnetic remanence is similar to that of Tagish Lake and samples returned from asteroid Ryugu, with a very weak paleointensity (5.4â8.3 AU. An origin in the cold, outer regions of the solar system is further supported by the presence of distinct, porous clasts enriched in aliphaticârich organics that potentially retain a pristine interstellar composition. Together, our observations support a genetic relationship between Tarda and Tagish Lake
Measurement of the cosmic microwave background polarization lensing power spectrum from two years of POLARBEAR data
We present a measurement of the gravitational lensing deflection power spectrum reconstructed with two seasons of cosmic microwave background polarization data from the POLARBEAR experiment. Observations were taken at 150 GHz from 2012 to 2014 and surveyed three patches of sky totaling 30 square degrees. We test the consistency of the lensing spectrum with a cold dark matter cosmology and reject the no-lensing hypothesis at a confidence of 10.9Ï, including statistical and systematic uncertainties. We observe a value of AL = 1.33 ± 0.32 (statistical) ±0.02 (systematic) ±0.07 (foreground) using all polarization lensing estimators, which corresponds to a 24% accurate measurement of the lensing amplitude. Compared to the analysis of the first- year data, we have improved the breadth of both the suite of null tests and the error terms included in the estimation of systematic contamination
Internal delensing of cosmic microwave background polarization B-Modes with the POLARBEAR experiment
International audienceUsing only cosmic microwave background polarization data from the polarbear experiment, we measure B-mode polarization delensing on subdegree scales at more than 5Ï significance. We achieve a 14% B-mode power variance reduction, the highest to date for internal delensing, and improve this result to 22% by applying for the first time an iterative maximum a posteriori delensing method. Our analysis demonstrates the capability of internal delensing as a means of improving constraints on inflationary models, paving the way for the optimal analysis of next-generation primordial B-mode experiments
Thalidomide-Related Eosinophilic Pneumonia: A case report and brief literature review
Thalidomide has regained value in the multimodality treatment of leprosy, multiple myeloma, prostate, ovarian and renal cancer. Complications related to arterial and venous complications are well described. However, pulmonary complications remain relatively uncommon. The most common pulmonary side-effect reported is non-specific dyspnea. We report a patient with multiple myeloma, who developed an eosinophilic pneumonia, shortly after starting thalidomide. She had complete resolution of her symptoms and pulmonary infiltrates on discontinuation of the drug and treatment with corticosteroids. Physicians should be cognizant of this potential complication in patients receiving thalidomide who present with dyspnea and pulmonary infiltrates
Disturbed flow induces a sustained, stochastic NF-ÎșB activation which may support intracranial aneurysm growth in vivo
Intracranial aneurysms are associated with disturbed velocity patterns, and chronic inflammation, but the relevance for these findings are currently unknown. Here, we show that (disturbed) shear stress induced by vortices is a sufficient condition to activate the endothelial NF-kB pathway, possibly through a mechanism of mechanosensor de-activation. We provide evidence for this statement through in-vitro live cell imaging of NF-kB in HUVECs exposed to different flow conditions, stochastic modelling of flow induced NF-kB activation and induction of disturbed flow in mouse carotid arteries. Finally, CFD and immunofluorescence on human intracranial aneurysms showed a correlation similar to the mouse vessels, suggesting that disturbed shear stress may lead to sustained NF-kB activation thereby offering an explanation for the close association between disturbed flow and intracranial aneurysms
Development of the Low Frequency Telescope Focal Plane Detector Modules for LiteBIRD
LiteBIRD is a JAXA-led strategic large-class satellite mission designed to
measure the polarization of the cosmic microwave background and Galactic
foregrounds from 34 to 448 GHz across the entire sky from L2 in the late 2020s.
The scientific payload includes three telescopes which are called the low-,
mid-, and high-frequency telescopes each with their own receiver that covers a
portion of the mission's frequency range. The low frequency telescope will map
synchrotron radiation from the Galactic foreground and the cosmic microwave
background. We discuss the design, fabrication, and characterization of the
low-frequency focal plane modules for low-frequency telescope, which has a
total bandwidth ranging from 34 to 161 GHz. There will be a total of 4
different pixel types with 8 overlapping bands to cover the full frequency
range. These modules are housed in a single low-frequency focal plane unit
which provides thermal isolation, mechanical support, and radiative baffling
for the detectors. The module design implements multi-chroic lenslet-coupled
sinuous antenna arrays coupled to transition edge sensor bolometers read out
with frequency-domain mulitplexing. While this technology has strong heritage
in ground-based cosmic microwave background experiments, the broad frequency
coverage, low optical loading conditions, and the high cosmic ray background of
the space environment require further development of this technology to be
suitable for LiteBIRD. In these proceedings, we discuss the optical and
bolometeric characterization of a triplexing prototype pixel with bands
centered on 78, 100, and 140 GHz.Comment: SPIE Astronomical Telescope + Instrumentation (AS22
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