482 research outputs found
NeuDA: Neural Deformable Anchor for High-Fidelity Implicit Surface Reconstruction
This paper studies implicit surface reconstruction leveraging differentiable
ray casting. Previous works such as IDR and NeuS overlook the spatial context
in 3D space when predicting and rendering the surface, thereby may fail to
capture sharp local topologies such as small holes and structures. To mitigate
the limitation, we propose a flexible neural implicit representation leveraging
hierarchical voxel grids, namely Neural Deformable Anchor (NeuDA), for
high-fidelity surface reconstruction. NeuDA maintains the hierarchical anchor
grids where each vertex stores a 3D position (or anchor) instead of the direct
embedding (or feature). We optimize the anchor grids such that different local
geometry structures can be adaptively encoded. Besides, we dig into the
frequency encoding strategies and introduce a simple hierarchical positional
encoding method for the hierarchical anchor structure to flexibly exploit the
properties of high-frequency and low-frequency geometry and appearance.
Experiments on both the DTU and BlendedMVS datasets demonstrate that NeuDA can
produce promising mesh surfaces.Comment: Accepted to CVPR 2023, project page:
https://3d-front-future.github.io/neud
An Anti-Jamming Strategy for Disco Intelligent Reflecting Surfaces Based Fully-Passive Jamming Attacks
Emerging intelligent reflecting surfaces (IRSs) significantly improve system
performance, while also pose a huge risk for physical layer security. A disco
IRS (DIRS), i.e., an illegitimate IRS with random time-varying reflection
properties, can be employed by an attacker to actively age the channels of
legitimate users (LUs). Such active channel aging (ACA) generated by the
DIRS-based fully-passive jammer (FPJ) can be applied to jam multi-user
multiple-input single-output (MU-MISO) systems without relying on either
jamming power or LU channel state information (CSI). To address the significant
threats posed by the DIRS-based FPJ, an anti-jamming strategy is proposed that
requires only the statistical characteristics of DIRS-jammed channels instead
of their CSI. Statistical characteristics of DIRS-jammed channels are first
derived, and then the anti-jamming precoder is given based on the derived
statistical characteristics. Numerical results are also presented to evaluate
the effectiveness of the proposed anti-jamming precoder against the DIRS-based
FPJ
Disco Intelligent Reflecting Surfaces: Active Channel Aging for Fully-Passive Jamming Attacks
Due to the open communications environment in wireless channels, wireless
networks are vulnerable to jamming attacks. However, existing approaches for
jamming rely on knowledge of the legitimate users' (LUs') channels, extra
jamming power, or both. To raise concerns about the potential threats posed by
illegitimate intelligent reflecting surfaces (IRSs), we propose an alternative
method to launch jamming attacks on LUs without either LU channel state
information (CSI) or jamming power. The proposed approach employs an
adversarial IRS with random phase shifts, referred to as a "disco" IRS (DIRS),
that acts like a "disco ball" to actively age the LUs' channels. Such active
channel aging (ACA) interference can be used to launch jamming attacks on
multi-user multiple-input single-output (MU-MISO) systems. The proposed
DIRS-based fully-passive jammer (FPJ) can jam LUs with no additional jamming
power or knowledge of the LU CSI, and it can not be mitigated by classical
anti-jamming approaches. A theoretical analysis of the proposed DIRS-based FPJ
that provides an evaluation of the DIRS-based jamming attacks is derived. Based
on this detailed theoretical analysis, some unique properties of the proposed
DIRS-based FPJ can be obtained. Furthermore, a design example of the proposed
DIRS-based FPJ based on one-bit quantization of the IRS phases is demonstrated
to be sufficient for implementing the jamming attack. In addition, numerical
results are provided to show the effectiveness of the derived theoretical
analysis and the jamming impact of the proposed DIRS-based FPJ
IRS-Enhanced Anti-Jamming Precoding Against DISCO Physical Layer Jamming Attacks
Illegitimate intelligent reflective surfaces (IRSs) can pose significant
physical layer security risks on multi-user multiple-input single-output
(MU-MISO) systems. Recently, a DISCO approach has been proposed an illegitimate
IRS with random and time-varying reflection coefficients, referred to as a
"disco" IRS (DIRS). Such DIRS can attack MU-MISO systems without relying on
either jamming power or channel state information (CSI), and classical
anti-jamming techniques are ineffective for the DIRS-based fully-passive
jammers (DIRS-based FPJs). In this paper, we propose an IRS-enhanced
anti-jamming precoder against DIRS-based FPJs that requires only statistical
rather than instantaneous CSI of the DIRS-jammed channels. Specifically, a
legitimate IRS is introduced to reduce the strength of the DIRS-based jamming
relative to the transmit signals at a legitimate user (LU). In addition, the
active beamforming at the legitimate access point (AP) is designed to maximize
the signal-to-jamming-plus-noise ratios (SJNRs). Numerical results are
presented to evaluate the effectiveness of the proposed IRS-enhanced
anti-jamming precoder against DIRS-based FPJs.Comment: This paper has been accepted by IEEE ICC 202
Green Fluorescent Protein GFP-Chromophore-Based Probe for the Detection of Mitochondrial Viscosity in Living Cells
Viscosity is a pivotal factor for indicating the dysfunction of the mitochondria. To date, most of the fluorescent probes developed for mitochondrial viscosity have been designed using BODIPY, hemicyanine, or pyridine-based molecular rotors as part of the core structure. Our aim with this research was to extend the range of suitable fluorophores available for the construction of such fluorescent molecular rotors for evaluating the viscosity of mitocondria. Herein, we have developed a green fluorescent protein (GFP)-chromophore-based fluorescent probe (MIT-V) for the detection of mitochondrial viscosity in live cells. MIT-V exhibited a high sensitivity toward viscosity (from 7.9 cP to 438.4 cP). The "off-on"sensing mechanism of MIT-V was ascribed to the restricted rotation of single bonds and excited-state C= C double bonds of MIT-V. Cell studies indicated that MIT-V targets the mitochondria and that it was able to monitor real-time changes in the viscosity of live HeLa cell mitochondria. Therefore, we propose that MIT-V can be used as an effective chemosensor for the real-time imaging of mitochondrial viscosity in live cells. Our results clearly demonstrate the utility of such GFP-chromophore-based derivatives for the development of viscosity-sensitive systems.</p
Green Fluorescent Protein GFP-Chromophore-Based Probe for the Detection of Mitochondrial Viscosity in Living Cells
Viscosity is a pivotal factor for indicating the dysfunction of the mitochondria. To date, most of the fluorescent probes developed for mitochondrial viscosity have been designed using BODIPY, hemicyanine, or pyridine-based molecular rotors as part of the core structure. Our aim with this research was to extend the range of suitable fluorophores available for the construction of such fluorescent molecular rotors for evaluating the viscosity of mitocondria. Herein, we have developed a green fluorescent protein (GFP)-chromophore-based fluorescent probe (MIT-V) for the detection of mitochondrial viscosity in live cells. MIT-V exhibited a high sensitivity toward viscosity (from 7.9 cP to 438.4 cP). The "off-on"sensing mechanism of MIT-V was ascribed to the restricted rotation of single bonds and excited-state C= C double bonds of MIT-V. Cell studies indicated that MIT-V targets the mitochondria and that it was able to monitor real-time changes in the viscosity of live HeLa cell mitochondria. Therefore, we propose that MIT-V can be used as an effective chemosensor for the real-time imaging of mitochondrial viscosity in live cells. Our results clearly demonstrate the utility of such GFP-chromophore-based derivatives for the development of viscosity-sensitive systems.</p
Imprinting and Promoter Usage of Insulin-Like Growth Factor II in Twin Discordant Placenta
Case reports from infant twins suggest that abnormal genomic imprinting may be one of the important causes of twin discordance, but it is unknown whether abnormal genomic imprinting occurs in the placenta. Therefore, we sought to determine the relationship between the imprinting of insulin-like growth factor II (IGF-II) in placenta and twin discordance. We analyzed the imprinting and promoter usage of IGF-II in placenta of normal twins (T0 group), weight discordance (T1 group), and phenotype discordance (T2 group). We found the incidence of loss of imprinting (LOI) for IGF-II was higher in the T2 group than that in the T0 and T1 groups, while there was no difference between T0 and T1 groups. The transcripts of promoter 3 were lower in the T2 group than in the T0 and T1 groups, and lower in the twin placenta with LOI than in those with normal imprinting. Our findings indicate that the promoter 3 specific LOI of the IGF-II gene may be closely related with phenotype discordance, not weight discordance
Anti-Jamming Precoding Against Disco Intelligent Reflecting Surfaces Based Fully-Passive Jamming Attacks
Emerging intelligent reflecting surfaces (IRSs) significantly improve system
performance, but also pose a huge risk for physical layer security. Existing
works have illustrated that a disco IRS (DIRS), i.e., an illegitimate IRS with
random time-varying reflection properties (like a "disco ball"), can be
employed by an attacker to actively age the channels of legitimate users (LUs).
Such active channel aging (ACA) generated by the DIRS can be employed to jam
multi-user multiple-input single-output (MU-MISO) systems without relying on
either jamming power or LU channel state information (CSI). To address the
significant threats posed by DIRS-based fully-passive jammers (FPJs), an
anti-jamming precoder is proposed that requires only the statistical
characteristics of the DIRS-based ACA channels instead of their CSI. The
statistical characteristics of DIRS-jammed channels are first derived, and then
the anti-jamming precoder is derived based on the statistical characteristics.
Furthermore, we prove that the anti-jamming precoder can achieve the maximum
signal-to-jamming-plus-noise ratio (SJNR). To acquire the ACA statistics
without changing the system architecture or cooperating with the illegitimate
DIRS, we design a data frame structure that the legitimate access point (AP)
can use to estimate the statistical characteristics. During the designed data
frame, the LUs only need to feed back their received power to the legitimate AP
when they detect jamming attacks. Numerical results are also presented to
evaluate the effectiveness of the proposed anti-jamming precoder against the
DIRS-based FPJs and the feasibility of the designed data frame used by the
legitimate AP to estimate the statistical characteristics.Comment: This paper has been submitted for possible publicatio
Imaging cell lineage with a synthetic digital recording system
Cell lineage plays a pivotal role in cell fate determination. Chow et al. demonstrate the use of an integrase-based synthetic barcode system called intMEMOIR, which uses the serine integrase Bxb1 to perform irreversible nucleotide edits. Inducible editing either deletes or inverts its target region, thus encoding information in three-state memory elements, or trits, and avoiding undesired recombination events. Using intMEMOIR combined with single-molecule fluorescence in situ hybridization, the authors were able to identify clonal structures as well as gene expression patterns in the fly brain, enabling both clonal analysis and expression profiling with intact spatial information. The ability to visualize cell lineage relationships directly within their native tissue context provides insights into development and disease
Versatile Ratiometric Fluorescent Probe Based on the Two-Isophorone Fluorophore for Sensing Nitroxyl
Nitroxyl (HNO) is closely linked with numerous biological processes. Fluorescent probes provide a visual tool for determining HNO. Due to fluorescence quenching by HNO-responsive recognition groups, most of the current fluorescent probes exhibit an "off-on"fluorescence response. As such, the single fluorescence signal of these probes is easily affected by external factors such as the microenvironment, sensor concentration, and photobleaching. Herein, we have developed a ratiometric fluorescent probe (CHT-P) based on our previously developed two-isophorone fluorophore. CHT-P could be used to determine HNO through ratiometric signal readouts with high selectivity and sensitivity, ensuring the accurate quantitative detection of HNO. Additionally, the probe exhibited low cytotoxicity, was cell permeable, and could be used for ratiometric imaging of HNO in cells. Finally, CHT-P-coated portable test strips were used to determine HNO using the solid-state fluorescence signal readout. </p
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