2,715 research outputs found
Possible Deuteron-like Molecular States Composed of Heavy Baryons
We perform a systematic study of the possible loosely bound states composed
of two charmed baryons or a charmed baryon and an anti-charmed baryon within
the framework of the one boson exchange (OBE) model. We consider not only the
exchange but also the , , , and
exchanges. The mixing effects for the spin-triplets are also taken into
account. With the derived effective potentials, we calculate the binding
energies and root-mean-square (RMS) radii for the systems
, ,
,
and
. Our numerical results indicate that: (1)
the H-dibaryon-like state does not exist; (2) there may
exist four loosely bound deuteron-like states and
with small binding energies and large RMS radii.Comment: 17 pages, 32 figure
1-(2-Chlorobenzylidene)-2-(2,4-dinitrophenyl)hydrazine
In the title compound, C13H9ClN4O4, there are two crystallographically independent molecules in the asymmetric unit, which have very similar conformations. The C=N—N angles in each independent molecule are 115.0 (2) and 116.6 (2)°, which are significantly smaller than the ideal value of 120° expected for sp
2-hybridized N atoms. This is probably a consequence of repulsion between the nitrogen lone pairs and the adjacent N—N bonds. Two bifurcated intramolecular N—H⋯O hydrogen bonds help to establish the molecular conformation and consolidate the crystal packing
Scale-MIA: A Scalable Model Inversion Attack against Secure Federated Learning via Latent Space Reconstruction
Federated learning is known for its capability to safeguard participants'
data privacy. However, recently emerged model inversion attacks (MIAs) have
shown that a malicious parameter server can reconstruct individual users' local
data samples through model updates. The state-of-the-art attacks either rely on
computation-intensive search-based optimization processes to recover each input
batch, making scaling difficult, or they involve the malicious parameter server
adding extra modules before the global model architecture, rendering the
attacks too conspicuous and easily detectable.
To overcome these limitations, we propose Scale-MIA, a novel MIA capable of
efficiently and accurately recovering training samples of clients from the
aggregated updates, even when the system is under the protection of a robust
secure aggregation protocol. Unlike existing approaches treating models as
black boxes, Scale-MIA recognizes the importance of the intricate architecture
and inner workings of machine learning models. It identifies the latent space
as the critical layer for breaching privacy and decomposes the complex recovery
task into an innovative two-step process to reduce computation complexity. The
first step involves reconstructing the latent space representations (LSRs) from
the aggregated model updates using a closed-form inversion mechanism,
leveraging specially crafted adversarial linear layers. In the second step, the
whole input batches are recovered from the LSRs by feeding them into a
fine-tuned generative decoder.
We implemented Scale-MIA on multiple commonly used machine learning models
and conducted comprehensive experiments across various settings. The results
demonstrate that Scale-MIA achieves excellent recovery performance on different
datasets, exhibiting high reconstruction rates, accuracy, and attack efficiency
on a larger scale compared to state-of-the-art MIAs
Linear optical quantum computation with imperfect entangled photon-pair sources and inefficient non-photon-number-resolving detectors
We propose a scheme for efficient cluster state quantum computation by using
imperfect polarization-entangled photon-pair sources, linear optical elements
and inefficient non-photon-number-resolving detectors. The efficiency threshold
for loss tolerance in our scheme requires the product of source and detector
efficiencies should be >1/2 - the best known figure. This figure applies to
uncorrelated loss. We further find that the loss threshold is unaffected by
correlated loss in the photon pair source. Our approach sheds new light on
efficient linear optical quantum computation with imperfect experimental
conditions.Comment: 5 pages, 2 figure
Optical loss compensation in a bulk left-handed metamaterial by the gain in quantum dots
A bulk left-handed metamaterial with fishnet structure is investigated to
show the optical loss compensation via surface plasmon amplification, with the
assistance of a Gaussian gain in PbS quantum dots. The optical resonance
enhancement around 200 THz is confirmed by the retrieval method. By exploring
the dependence of propagation loss on the gain coefficient and metamaterial
thickness, we verify numerically that the left-handed response can endure a
large propagation thickness with ultralow and stable loss under a certain gain
coefficient.Comment: 6 pages with 4 figure
Radiogenic chromium isotope evidence for the earliest planetary volcanism and crust formation in the Solar system
A Deep Reinforcement Learning Approach to Two-Timescale Transmission for RIS-aided Multiuser MISO systems
Reconfigurable intelligent surface (RIS) has drawn great attention recently as a promising technology for future wireless networks. In this letter, considering the two-timescale transmission protocol, we investigate the joint design of the transmit beamforming at the base station (BS) with instantaneous channel state information (CSI) and the RIS phase shifts with statistical CSI. Due to the large number of RIS elements, this design issue usually suffers from high computational complexity. To resolve the non-convexity issue with low complexity, we propose a novel deep reinforcement learning (DRL) framework, which contains two agents applying proximal policy optimization (PPO) based algorithm. Experiment results demonstrate that the proposed algorithm has comparable spectral efficiency performance to the state-of-the-art methods with substantially reduced computational delay
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