70 research outputs found
Microwave Chirality Imaging for the Early Diagnosis of Neurological Degenerative Diseases
We propose a system to visualize the chirality of the protein in brains,
which would be helpful to diagnose early neurological degenerative diseases in
vivo. These neurological degenerative diseases often occur along with some mark
proteins. By nanoparticle instilling and metamaterial technique, the chiral
effect of the mark proteins is assumed to be manifest in microwave regime.
Therefore, by detecting the transmission of cross-polarization, we could detect
the chirality that rotates the microwave polarization angle. We developed a
numerical method to simulate the electromagnetic response upon chiral
(bi-isotropic) material. Then a numerical experiment was conduct with a
numerical head phantom. A map of cross-polarized transmission magnitude can be
reached by sweeping the antenna pair. The imaging results matches well with the
distribution of chiral materials. It suggests that the proposed method would be
capable of in vivo imaging of neurological degenerative disease using
microwaves
Detecting a disk bending wave in a barred-spiral galaxy at redshift 4.4
The recent discovery of barred spiral galaxies in the early universe ()
poses questions of how these structures form and how they influence galaxy
properties in the early universe. In this study, we investigate the morphology
and kinematics of the far infrared (FIR) continuum and [CII] emission in
BRI1335-0417 at from ALMA observations. The variations in
position angle and ellipticity of the isophotes show the characteristic
signature of a barred galaxy. The bar, kpc long in radius
and bridging the previously identified two-armed spiral, is evident in both
[CII] and FIR images, driving the galaxy's rapid evolution by channelling gas
towards the nucleus. Fourier analysis of the [CII] velocity field reveals an
unambiguous mode with a line-of-sight velocity amplitude of up to
km s; the plausible explanation is the disk's vertical
bending mode triggered by external perturbation, which presumably induced the
high star formation rate and the bar/spiral structure. The bar identified in
[CII] and FIR images of the gas-rich disk galaxy (\% of the total
mass within radius disk scale lengths) suggests a new
perspective of early bar formation -- a gravitationally unstable gas-rich disk
creating a star-forming gaseous bar, rather than a stellar bar emerging from a
pre-existing stellar disk.Comment: Submitted to MNRAS. We welcome comments
A Knotted Meta-molecule with 2-D Isotropic Optical Activity Rotating the Incident Polarization by 90{\deg}
Optical activity is the ability of chiral materials to rotate
linearly-polarized (LP) electromagnetic waves. Because of their intrinsic
asymmetry, traditional chiral molecules usually lack isotropic performance, or
at best only possess a weak form of chirality. Here we introduce a knotted
chiral meta-molecule that exhibits optical activity corresponding to a 90{\deg}
polarization rotation of the incident waves. More importantly, arising from the
continuous multi-fold rotational symmetry of the chiral torus knot structure,
the observed polarization rotation behavior is found to be independent of how
the incident wave is polarized. In other words, the proposed chiral knot
structure possesses two-dimensional (2-D) isotropic optical activity as
illustrated in Fig. 1, which has been experimentally validated in the microwave
spectrum. The proposed chiral torus knot represents the most optically active
meta-molecule reported to date that is intrinsically isotropic to the incident
polarization
The SAMI Galaxy Survey: impact of black hole activity on galaxy spin-filament alignments
The activity of central supermassive black holes might affect the alignment
of galaxy spin axes with respect to the closest cosmic filaments. We exploit
the SAMI Galaxy Survey to study possible relations between black hole activity
and the spin-filament alignments of stars and ionised gas separately. To
explore the impact of instantaneous black hole activity, active galaxies are
selected according to emission-line diagnostics. Central stellar velocity
dispersion () is used as a proxy for black hole mass and its
integrated activity. We find evidence for the gas spin-filament alignments to
be influenced by AGN, with Seyfert galaxies showing a stronger perpendicular
alignment at fixed bulge mass with respect to galaxies where ionisation is
consequence of low-ionizaition nuclear emission-line regions (LINERs) or old
stellar populations (retired galaxies). On the other hand, the greater
perpendicular tendency for the stellar spin-filament alignments of high-bulge
mass galaxies is dominated by retired galaxies. Stellar alignments show a
stronger correlation with compared to the gas alignments. We confirm
that bulge mass () is the primary parameter of correlation for both
stellar and gas spin-filament alignments (with no residual dependency left for
), while is the most important property for secular star
formation quenching (with no residual dependency left for ). These
findings indicate that and are the most predictive
parameters of two different galaxy evolution processes, suggesting mergers
trigger spin-filament alignment flips and integrated black hole activity drives
star formation quenching.Comment: 20 pages, 16 figures, accepted for publication in MNRA
Introducing v0.5 of the AI Safety Benchmark from MLCommons
This paper introduces v0.5 of the AI Safety Benchmark, which has been created by the MLCommons AI Safety Working Group. The AI Safety Benchmark has been designed to assess the safety risks of AI systems that use chat-tuned language models. We introduce a principled approach to specifying and constructing the benchmark, which for v0.5 covers only a single use case (an adult chatting to a general-purpose assistant in English), and a limited set of personas (i.e., typical users, malicious users, and vulnerable users). We created a new taxonomy of 13 hazard categories, of which 7 have tests in the v0.5 benchmark. We plan to release version 1.0 of the AI Safety Benchmark by the end of 2024. The v1.0 benchmark will provide meaningful insights into the safety of AI systems. However, the v0.5 benchmark should not be used to assess the safety of AI systems. We have sought to fully document the limitations, flaws, and challenges of v0.5. This release of v0.5 of the AI Safety Benchmark includes (1) a principled approach to specifying and constructing the benchmark, which comprises use cases, types of systems under test (SUTs), language and context, personas, tests, and test items; (2) a taxonomy of 13 hazard categories with definitions and subcategories; (3) tests for seven of the hazard categories, each comprising a unique set of test items, i.e., prompts. There are 43,090 test items in total, which we created with templates; (4) a grading system for AI systems against the benchmark; (5) an openly available platform, and downloadable tool, called ModelBench that can be used to evaluate the safety of AI systems on the benchmark; (6) an example evaluation report which benchmarks the performance of over a dozen openly available chat-tuned language models; (7) a test specification for the benchmark
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world
Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic.
Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality.
Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States.
Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis.
Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection
- …