718 research outputs found
μ3-Dodecatungsto(V,VI)aluminato-κ3 O:O′:O′′-tris[aquabis(ethylenediamine-κ2 N,N′)copper(II)]
The title compound, [AlCu3W12O40(C2H8N2)6(H2O)3], was prepared under hydrothermal conditions. The Cu2+ ion displays an elongated octahedral geometry defined by one bridging O atom from the polyoxidoanion and a coordinated water molecule in axial positions and four N atoms of the two chelating ethylenediamine (en) ligands in equatorial positions. The one-electron reduced [AlW12O40]6− anion coordinates three [Cu(en)(H2O)]2+ fragments, generating a neutral tri-supported Keggin-type polyoxidometalate (POM). This tri-supported POM is located in a special position of symmetry and therefore O atoms from the central AlO4 tetrahedron are disordered over two sets of sites. Disorder is also observed for three other bridging O atoms of the POM. In the crystal, molecules are connected via N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional framework
Feature Fusion from Head to Tail for Long-Tailed Visual Recognition
The imbalanced distribution of long-tailed data presents a considerable
challenge for deep learning models, as it causes them to prioritize the
accurate classification of head classes but largely disregard tail classes. The
biased decision boundary caused by inadequate semantic information in tail
classes is one of the key factors contributing to their low recognition
accuracy. To rectify this issue, we propose to augment tail classes by grafting
the diverse semantic information from head classes, referred to as head-to-tail
fusion (H2T). We replace a portion of feature maps from tail classes with those
belonging to head classes. These fused features substantially enhance the
diversity of tail classes. Both theoretical analysis and practical
experimentation demonstrate that H2T can contribute to a more optimized
solution for the decision boundary. We seamlessly integrate H2T in the
classifier adjustment stage, making it a plug-and-play module. Its simplicity
and ease of implementation allow for smooth integration with existing
long-tailed recognition methods, facilitating a further performance boost.
Extensive experiments on various long-tailed benchmarks demonstrate the
effectiveness of the proposed H2T. The source code is available at
https://github.com/Keke921/H2T.Comment: Accepted to AAAI24, similar to the conference version. Add the
supplementr
Strategies for Searching Video Content with Text Queries or Video Examples
The large number of user-generated videos uploaded on to the Internet
everyday has led to many commercial video search engines, which mainly rely on
text metadata for search. However, metadata is often lacking for user-generated
videos, thus these videos are unsearchable by current search engines.
Therefore, content-based video retrieval (CBVR) tackles this metadata-scarcity
problem by directly analyzing the visual and audio streams of each video. CBVR
encompasses multiple research topics, including low-level feature design,
feature fusion, semantic detector training and video search/reranking. We
present novel strategies in these topics to enhance CBVR in both accuracy and
speed under different query inputs, including pure textual queries and query by
video examples. Our proposed strategies have been incorporated into our
submission for the TRECVID 2014 Multimedia Event Detection evaluation, where
our system outperformed other submissions in both text queries and video
example queries, thus demonstrating the effectiveness of our proposed
approaches
Structure-Mediated Excitation of Air Plasma and Silicon Plasma Expansion in Femtosecond Laser Pulses Ablation
Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number,which in turn significantly affects successive laser-material interactions. By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy, here we present direct visualization of the excitation of air plasma induced by the reflected laser during the second pulse irradiation.The interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction, showing anisotropic expansion dynamics in different directions. We further demonstrate the vanishing of air plasma as the pulse number increases because of the generation of a rough surface without light focusing ability. In the scenario, the interaction of air plasma and silicon plasma disappears; the expansion of the silicon plasma and shockwave restores its original characteristic that is dominated by the laser-material coupling.The results show that the excitation of air plasma and the laser-material coupling involved in laser-induced plasma and shockwave expansion are structure mediated and dependent on the pulse number, which is of fundamental importance for deep insight into the nature of laser-material interactions during multiple pulses ablation
Recommended from our members
Chemokine receptor CXCR3 is important for lung tissue damage and airway remodeling induced by short-term exposure to cigarette smoking in mice
Aim: To investigate the role of chemokine receptor CXCR3 in cigarette smoking (CS)-induced pulmonary damage. Methods: CXCR3 knockout (CXCR3-/-) mice were used. Differences in airspace enlargement, mRNA expression of matrix metalloproteinases (MMPs), transforming growth factor (TGF) β1, CXCL10 in lung homogenates, and CXCL10 content in bronchoalveolar lavage (BAL) fluids and homogenates were compared between CXCR3-/- mice and wild-type (WT) mice three days after three-day CS exposures. Results: The linear intercept was significantly less in CXCR3-/- mice than in WT mice (30.1±0.9 μm vs 40.3±2.4 μm, P<0.01). Morphologically, collagen was deposited less around airways and vessels in CXCR3-/- mice. The lung hydroxyproline content was significantly lower in CXCR3-/- mice than in WT mice (6.0±1.0 μg/mL vs 12.0±1.6 μg/mL, P<0.05). Profoundly lower mRNA expression of MMP2, MMP12, TGFβ1, and CXCL10 was seen in lung homogenates from CXCR3-/- mice. CXCL10 concentrations in BAL fluid and lung homogenates were significantly lower in CXCR3-/- mice than in WT mice (BAL fluid: 19.3±1.4 pg/mL vs 24.8±1.6 pg/mL, P<0.05; lung homogenates: 76.6±7.0 pg/mL vs 119.5±15.9 pg/mL, P<0.05). Conclusion: CXCR3 is important in mediating lung tissue damage and airway remodeling following a short-term CS insult, possibly through up-regulation of CXCL10 and inducement of mRNA expression of MMPs. Targeting CXCR3 may be helpful for prevention of CS-induced pulmonary pathology
Method of determining cosmological parameter ranges with samples of candles with an intrinsic distribution
In this paper, the effect of the intrinsic distribution of cosmological
candles is investigated. We find that, in the case of a narrow distribution,
the deviation of the observed modulus of sources from the expected central
value could be estimated within a ceratin range. We thus introduce a lower and
upper limits of , and , to
estimate cosmological parameters by applying the conventional minimizing method. We apply this method to a gamma-ray burst (GRB) sample as well as
to a combined sample including this GRB sample and an SN Ia sample. Our
analysis shows that: a) in the case of assuming an intrinsic distribution of
candles of the GRB sample, the effect of the distribution is obvious and should
not be neglected; b) taking into account this effect would lead to a poorer
constraint of the cosmological parameter ranges. The analysis suggests that in
the attempt of constraining the cosmological model with current GRB samples,
the results tend to be worse than what previously thought if the mentioned
intrinsic distribution does exist.Comment: 6 pages,4 figures,1 tables.Data updated. Main conclusion unchange
Antinociceptive effects of morphine and naloxone in mu-opioid receptor knockout mice transfected with the MORS196A gene
<p>Abstract</p> <p>Background</p> <p>Opioid analgesics such as morphine and meperidine have been used to control moderate to severe pain for many years. However, these opioids have many side effects, including the development of tolerance and dependence after long-term use, which has limited their clinical use. We previously reported that mutations in the mu-opioid receptors (MOR) S196L and S196A rendered them responsive to the opioid antagonist naloxone without altering the agonist phenotype. In MORS196A knock-in mice, naloxone and naltrexone were antinociceptive but did not cause tolerance or physical dependence. In this study we delivery this mutated MOR gene into pain related pathway to confirm the possibility of <it>in vivo </it>transfecting MORS196A gene and using naloxone as a new analgesic agent.</p> <p>Methods</p> <p>The MOR-knockout (MOR-KO) mice were used to investigate whether morphine and naloxone could show antinociceptive effects when MORS196A gene was transfected into the spinal cords of MOR-KO mice. Double-stranded adeno-associated virus type 2 (dsAAV2) was used to deliver the MORS196A-enhanced green fluorescence protein (EGFP) gene by microinjected the virus into the spinal cord (S2/S3) dorsal horn region. Tail-flick test was used to measure the antinociceptive effect of drugs.</p> <p>Results</p> <p>Morphine (10 mg/kg, s.c.) and naloxone (10 mg/kg, s.c.) had no antinociceptive effects in MOR-KO mice before gene transfection. However, two or three weeks after the MOR-S196A gene had been injected locally into the spinal cord of MOR-KO mice, significant antinociceptive effects could be induced by naloxone or morphine. On the other hand, only morphine but not naloxone induced significant tolerance after sub-chronic treatment.</p> <p>Conclusion</p> <p>Transfecting the MORS196A gene into the spinal cord and systemically administering naloxone in MOR-KO mice activated the exogenously delivered mutant MOR and provided antinociceptive effect without causing tolerance. Since naloxone will not activate natural MOR in normal animals or humans, it is expected to produce fewer side effects and less tolerance and dependence than traditional opioid agonists do.</p
- …