227 research outputs found
YAP/TAZ-Inhibitor-Based Drug Delivery System for Cancer Therapy
The YES-associated protein (YAP) and the transcriptional co-activator with PDZ-binding motif (TAZ) are two important transcriptional co-activators in the Hippo signaling pathway, which play an essential role in organ size control, tumor suppression, tissue regeneration and stem cell self-renewal. However, aberrant activation of YAP and TAZ due to deregulation of the Hippo pathway or overexpression of YAP/TAZ and TEADs can promote cancer development. Hence, pharmacological inhibition of YAP and TAZ may be a useful approach to treat tumors with high YAP/TAZ activity. Here, we developed a YAP/TAZ-inhibitor (niflumic acid (NA))-based drug delivery system for enhanced cancer therapy. Through disrupting the interaction between the TEA domain transcription factors (TEADs) and YAP/TAZ, NA reduces the expression of downstream genes that promote tumor proliferation and migration. At the same time, other hydrophobic anti-cancer drug can be co-delivered to tumor site to improve the overall antitumor activity and decrease side effect. Our strategy may not only improve delivery of well-established anti-cancer drugs, but also further improve their efficacy through inhibiting YAP/TAZ activity
Millimetre-Resolution Photonics-Assisted Radar
Radar is essential in applications such as anti-collision systems for driving, airport security screening,
and contactless vital sign detection. The demand for high-resolution and real-time recognition in
radar applications is growing, driving the development of electronic radars with increased bandwidth,
higher frequency, and improved reconfigurability. However, conventional electronic approaches are
challenging due to limitations in synthesising radar signals, limiting performance.
In contrast, microwave photonics-enabled radars have gained interest because they offer numerous
benefits compared to traditional electronic methods. Photonics-assisted techniques provide a broad
fractional bandwidth at the optical carrier frequency and enable spectrum manipulation, producing
wideband and high-resolution radar signals in various formats. However, photonic-based methods
face limitations like low time-frequency linearity due to the inherent nonlinearity of lasers, restricted RF bandwidth, limited stability of the photonic frequency multipliers, and difficulties in achieving
extended sensing with dispersion-based techniques.
In response to these challenges, this thesis presents approaches for generating broadband radar
signals with high time-frequency linearity using recirculated unidirectional optical frequency-shifted
modulation. The photonics-assisted system allows flexible bandwidth tuning from sub-GHz to over 30
GHz and requires only MHz-level electronics. Such a system offers millimetre-level range resolution
and a high imaging refresh rate, detecting fast-moving objects using the ISAR technique. With
millimetre-level resolution and micrometre accuracy, this system supports contactless vital sign
detection, capturing precise respiratory patterns from simulators and a living body using a cane toad.
In the end, we highlight the promise of merging radar and LiDAR, foreshadowing future
advancements in sensor fusion for enhanced sensing performance and resilience
Transient Stability Analysis and Post-Fault Restart Strategy for Current-Limited Grid-Forming Converter
Grid-forming converters are attracting attention for their significant advantages in terms of stability in a weak grid and simulated inertia. However, while they offer great flexibility due to the use of power semiconductors, they are also affected by their low current-carrying capacity. This means that during a fault, instead of the usual voltage control, a current limiting control is active, which changes the dynamic performance of the converter and influences transient stability. This manuscript focuses on the dynamic performance of grid-forming converters during the restart phase at the post-fault period, and proposes an initial phase threshold to prevent the converter from going into current saturation. Based on this, the manuscript proposes several restart strategies during the post-fault period, by using some fast resynchronization methods in order to meet the requirements of the converter’s stable operation and fast active power restoration. Finally, the above findings and the proposed strategies are validated by a joint control hardware-in-the-loop system
GDN: A Stacking Network Used for Skin Cancer Diagnosis
Skin cancer, the primary type of cancer that can be identified by visual
recognition, requires an automatic identification system that can accurately
classify different types of lesions. This paper presents GoogLe-Dense Network
(GDN), which is an image-classification model to identify two types of skin
cancer, Basal Cell Carcinoma, and Melanoma. GDN uses stacking of different
networks to enhance the model performance. Specifically, GDN consists of two
sequential levels in its structure. The first level performs basic
classification tasks accomplished by GoogLeNet and DenseNet, which are trained
in parallel to enhance efficiency. To avoid low accuracy and long training
time, the second level takes the output of the GoogLeNet and DenseNet as the
input for a logistic regression model. We compare our method with four baseline
networks including ResNet, VGGNet, DenseNet, and GoogLeNet on the dataset, in
which GoogLeNet and DenseNet significantly outperform ResNet and VGGNet. In the
second level, different stacking methods such as perceptron, logistic
regression, SVM, decision trees and K-neighbor are studied in which Logistic
Regression shows the best prediction result among all. The results prove that
GDN, compared to a single network structure, has higher accuracy in optimizing
skin cancer detection.Comment: Published at ICSPS 202
Hydrodynamic Evolution of Sgr A East: The Imprint of A Supernova Remnant in the Galactic Center
We perform three-dimensional numerical simulations to study the hydrodynamic
evolution of Sgr A East, the only known supernova remnant (SNR) in the center
of our Galaxy, to infer its debated progenitor SN type and its potential impact
on the Galactic center environment. Three sets of simulations are performed,
each of which represents a represent a certain type of SN explosion (SN Iax, SN
Ia or core-collapse SN) expanding against a nuclear outflow of hot gas driven
by massive stars, whose thermodynamical properties have been well established
by previous work and fixed in the simulations. All three simulations can
simultaneously roughly reproduce the extent of Sgr A East and the position and
morphology of an arc-shaped thermal X-ray feature, known as the "ridge".
Confirming previous work, our simulations show that the ridge is the
manifestation of a strong collision between the expanding SN ejecta and the
nuclear outflow. The simulation of the core-collapse SN, with an assumed
explosion energy of 5x10^50 erg and an ejecta mass of 10 M_sun, can well match
the X-ray flux of the ridge, whereas the simulations of the SN Iax and SN Ia
explosions underpredict its X-ray emission, due to a smaller ejecta mass. All
three simulations constrain the age of Sgr A East to be <1500 yr and predict
that the ridge should fade out over the next few hundred years. We address the
implications of these results for our understanding of the Galactic center
environment.Comment: 21 pages, 18 figures. Accepted for publication on MNRA
Control parameters analysis, modeling and experiment
This article presents an in-situ comparative analysis and power quality tests of a newly developed photovoltaic charging system for e-bikes. The various control methods of the inverter are modeled and a single-phase grid-connected inverter is tested under different conditions. Models are constituted for two current control methods
the proportional resonance and the synchronous rotating frames. In order to determine the influence of the control parameters, the system is analyzed analytically in the time domain as well as in the frequency domain by simulation. The tests indicated the resonance instability of the photovoltaic inverter. The passivity impedance-based stability criterion is applied in order to analyze the phenomenon of resonance instability. In conclusion, the phase-locked loop (PLL) bandwidth and control parameters of the current loop have a major effect on the output admittance of the inverter, which should be adjusted to make the system stable.
Document type: Articl
Chandra X-ray Measurement of Gas-phase Heavy Element Abundances in the Central Parsec of the Galaxy
Elemental abundances are key to our understanding of star formation and
evolution in the Galactic center. Previous work on this topic has been based on
infrared (IR) observations, but X-ray observations have the potential of
constraining the abundance of heavy elements, mainly through their K-shell
emission lines. Using 5.7 Ms Chandra observations, we provide the first
abundance measurement of Si, S, Ar, Ca and Fe, in four prominent diffuse X-ray
features located in the central parsec of the Galaxy, which are the
manifestation of shock-heated hot gas. A two-temperature, non-equilibrium
ionization spectral model is employed to derive the abundances of these five
elements. In this procedure, a degeneracy is introduced due to uncertainties in
the composition of light elements, in particular, H, C and N. Assuming that the
hot gas is H-depleted but C- and N-enriched, as would be expected for a
standard scenario in which the hot gas is dominated by Wolf-Rayet star winds,
the spectral fit finds a generally subsolar abundance for the heavy elements.
If, instead, the light elements had a solar-like abundance, the heavy elements
have a fitted abundance of 1--2 solar. The /Fe abundance ratio,
on the other hand, is mostly supersolar and insensitive to the exact
composition of the light elements. These results are robust against potential
biases due to either a moderate spectral S/N or the presence of non-thermal
components. Implications of the measured abundances for the Galactic center
environment are addressed.Comment: 13 pages, 6 figures, Accepted for publication in MNRA
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