61 research outputs found
When SAM Meets Medical Images: An Investigation of Segment Anything Model (SAM) on Multi-phase Liver Tumor Segmentation
Learning to segmentation without large-scale samples is an inherent
capability of human. Recently, Segment Anything Model (SAM) performs the
significant zero-shot image segmentation, attracting considerable attention
from the computer vision community. Here, we investigate the capability of SAM
for medical image analysis, especially for multi-phase liver tumor segmentation
(MPLiTS), in terms of prompts, data resolution, phases. Experimental results
demonstrate that there might be a large gap between SAM and expected
performance. Fortunately, the qualitative results show that SAM is a powerful
annotation tool for the community of interactive medical image segmentation.Comment: Preliminary investigatio
Numerical Study of Magnetic Island Coalescence Using Magnetohydrodynamics With Adaptively Embedded Particle-In-Cell Model
Collisionless magnetic reconnection typically requires kinetic treatments
that are, in general, computationally expensive compared to fluid-based models.
In this study, we use the magnetohydrodynamics with adaptively embedded
particle-in-cell (MHD-AEPIC) model to study the interaction of two magnetic
flux ropes. This innovative model embeds one or more adaptive PIC regions into
a global MHD simulation domain such that the kinetic treatment is only applied
in regions where kinetic physics is prominent. We compare the simulation
results among three cases: 1) MHD with adaptively embedded PIC regions, 2) MHD
with statically (or fixed) embedded PIC regions, and 3) a full PIC simulation.
The comparison yields good agreement when analyzing their reconnection rates
and magnetic island separations, as well as the ion pressure tensor elements
and ion agyrotropy. In order to reach a good agreement among the three cases,
large adaptive PIC regions are needed within the MHD domain, which indicates
that the magnetic island coalescence problem is highly kinetic in nature where
the coupling between the macro-scale MHD and micro-scale kinetic physics is
important.Comment: 9 pages, 10 figure
Ambient air pollutants relate to hospital admissions for chronic obstructive pulmonary disease in Ganzhou, China
OBJECTIVE To evaluate the relationship between ambient air pollutants and chronic obstructive pulmonary disease in relatively low-polluted areas in China. METHODS Atmospheric pollutants levels and meteorological data were obtained from January 2016 to December 2020. The medical database including daily hospital admissions for chronic obstructive pulmonary disease (ICD10: J44) was derived from the First Affiliated Hospital of Gannan Medical University. The generalized additive model was used to analyze the percentage change with 95% confidence interval in daily hospital admissions for chronic obstructive pulmonary disease associated with a 10 µg/m3 increase in atmospheric pollutants levels. RESULTS In total, occurred 4,980 chronic obstructive pulmonary disease hospital admissions (not including emergency department visits) during 2016–2020. The mean concentrations of daily PM2.5, PM10, SO2, NO2, O3, and CO were 37.5 μg/m3, 60.1 μg/m3, 18.7 μg/m3, 23.5 μg/m3, 70.0 μg/m3, and 1.2 mg/m3 in Ganzhou. Each 10 µg/m3 increment of PM2.5, PM10, NO2, and O3 were significantly associated with 2.8% (95%CI: 1.0–4.7), 1.3% (95%CI: 0.3–2.4), 2.8% (95%CI: 0.4–5.4), and 1.5% (95%CI: 0.2–2.7) elevation in daily chronic obstructive pulmonary disease hospital admissions. The estimates of delayed effects of PM2.5, PM10, NO2, and O3 were observed at lag6, lag6, lag8, lag1, respectively. The health effects of particulate pollutants (PM2.5 and PM10) may be independent of other pollutants. The adverse effects of air pollutants were more evident in the warm season (May–Oct) than in the cold season (Nov–Apr). CONCLUSION Our study demonstrated that elevated concentrations of atmospheric pollutant (PM2.5, PM10, NO2, and O3), especially particulate pollutants, can be associated with increased daily count of hospital admissions for chronic obstructive pulmonary disease , which may promote further understanding of the potential hazards of relatively low levels of air pollution on chronic obstructive pulmonary disease and other respiratory disorders
Interplanetary magnetic field controlled Alfv\'{e}n wings at Earth during encounter of a coronal mass ejection
In the vicinity of Earth's orbit, the typical solar wind Alfv\'{e}n Mach
number exceeds 5, and the super-Alfv\'{e}nic solar wind drives a conventional
magnetosphere configuration. However, at the ejecta phase of an interplanetary
coronal mass ejection (ICME) event, the Alfv\'{e}n Mach number may experience a
significant reduction due to the intensified interplanetary magnetic field
(IMF) strength and decreased density. On 24 April 2023, an ICME reached Earth's
orbit. The solar wind density dropped to as low as 0.3 amu/cc while the IMF
strength is about 25 nT. As a result, the solar wind flow transitions to a
sub-Alfv\'{e}nic state with an Alfv\'{e}n Mach number of 0.4, providing
opportunities to investigate the interaction of planetary magnetospheres with
low Mach number solar wind. We carry out global simulations to investigate the
responses of Earth's magnetosphere to the sub-Alfv\'{e}nic ICME ejecta. The
global magnetohydrodynamic (MHD) simulation results show the formation of
Alfv\'{e}n wings as the solar wind becomes sub-Alfv\'{e}nic. Furthermore, the
sub-Alfv\'{e}nic period was characterized by the dominance of IMF By component,
causing the Alfv\'{e}n wings to extend towards the dawn and dusk sides. In this
paper, we present the structures of the magnetic field, plasma flow, and
current system around the Alfv\'{e}n wings. The global magnetospheric
convection under the sub-Alfv\'{e}nic solar wind condition is discussed in
depth. Our results achieve a new level of understanding about the interaction
between a magnetized body and sub-Alfv\'{e}nic upstream conditions, and provide
guidance for future observations
Nonlinear sub-cyclotron resonance as a formation mechanism for gaps in banded chorus
An interesting characteristic of magnetospheric chorus is the presence of a
frequency gap at , where is the electron
cyclotron angular frequency. Recent chorus observations sometimes show
additional gaps near and . Here we present a novel
nonlinear mechanism for the formation of these gaps using Hamiltonian theory
and test-particle simulations in a homogeneous, magnetized, collisionless
plasma. We find that an oblique whistler wave with frequency at a fraction of
the electron cyclotron frequency can resonate with electrons, leading to
effective energy exchange between the wave and particles
RNA Sequencing Reveals Differential Expression of Mitochondrial and Oxidation Reduction Genes in the Long-Lived Naked Mole-Rat When Compared to Mice
The naked mole-rat (Heterocephalus glaber) is a long-lived, cancer resistant rodent and there is a great interest in identifying the adaptations responsible for these and other of its unique traits. We employed RNA sequencing to compare liver gene expression profiles between naked mole-rats and wild-derived mice. Our results indicate that genes associated with oxidoreduction and mitochondria were expressed at higher relative levels in naked mole-rats. The largest effect is nearly 300-fold higher expression of epithelial cell adhesion molecule (Epcam), a tumour-associated protein. Also of interest are the protease inhibitor, alpha2-macroglobulin (A2m), and the mitochondrial complex II subunit Sdhc, both ageing-related genes found strongly over-expressed in the naked mole-rat. These results hint at possible candidates for specifying species differences in ageing and cancer, and in particular suggest complex alterations in mitochondrial and oxidation reduction pathways in the naked mole-rat. Our differential gene expression analysis obviated the need for a reference naked mole-rat genome by employing a combination of Illumina/Solexa and 454 platforms for transcriptome sequencing and assembling transcriptome contigs of the non-sequenced species. Overall, our work provides new research foci and methods for studying the naked mole-rat's fascinating characteristics
The case for studying other planetary magnetospheres and atmospheres in Heliophysics
Heliophysics is the field that "studies the nature of the Sun, and how it
influences the very nature of space - and, in turn, the atmospheres of
planetary bodies and the technology that exists there." However, NASA's
Heliophysics Division tends to limit study of planetary magnetospheres and
atmospheres to only those of Earth. This leaves exploration and understanding
of space plasma physics at other worlds to the purview of the Planetary Science
and Astrophysics Divisions. This is detrimental to the study of space plasma
physics in general since, although some cross-divisional funding opportunities
do exist, vital elements of space plasma physics can be best addressed by
extending the expertise of Heliophysics scientists to other stellar and
planetary magnetospheres. However, the diverse worlds within the solar system
provide crucial environmental conditions that are not replicated at Earth but
can provide deep insight into fundamental space plasma physics processes.
Studying planetary systems with Heliophysics objectives, comprehensive
instrumentation, and new grant opportunities for analysis and modeling would
enable a novel understanding of fundamental and universal processes of space
plasma physics. As such, the Heliophysics community should be prepared to
consider, prioritize, and fund dedicated Heliophysics efforts to planetary
targets to specifically study space physics and aeronomy objectives
Activation of GABAA Receptors in Colon Epithelium Exacerbates Acute Colitis
Emerging evidence indicates that gamma-aminobutyric acid (GABA) has many beneficial effects such as ameliorating immune and inflammatory response. But, here we reported that activation of GABAA receptors (GABAA Rs) aggravated dextran sulfate sodium (DSS)-induced colitis, although the expression of pro-inflammatory cytokines was inhibited. By contrast, blocking of GABAA Rs markedly alleviated DSS-induced colitis. Notably, GABAA Rs and glutamic acid decarboxylase 65/67 were significantly increased in colon mucosa of ulcerative colitis patients and the mouse model of colitis. Further studies showed that GABA treatment resulted in an increment of serum FITC-dextran following its oral administration, a decrement of transepithelial electrical resistance, and an increment of bacterial invasion, effects which were blocked by bicuculline. In addition, GABA inhibited the expression of tight junction proteins and mucin secretion in colitis colon. GABA also decreased the expression of ki-67 and increased cleaved-caspase 3 expression in intestinal epithelia. Our data indicate that the GABAA Rs activation within colon mucosa disrupts the intestinal barrier and increases the intestinal permeability which facilitates inflammatory reaction in colon. Meanwhile, the suppression effect of GABA on pro-inflammatory cytokines leads to insufficient bacteria elimination and further aggravated the bacteria invasion and inflammatory damage
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