739 research outputs found
The austenitic peak stress model of low-alloy steel at elevated temperature based on the valence electron theory
Lattice strain effects on the optical properties of MoS2 nanosheets.
"Strain engineering" in functional materials has been widely explored to tailor the physical properties of electronic materials and improve their electrical and/or optical properties. Here, we exploit both in plane and out of plane uniaxial tensile strains in MoS2 to modulate its band gap and engineer its optical properties. We utilize X-ray diffraction and cross-sectional transmission electron microscopy to quantify the strains in the as-synthesized MoS2 nanosheets and apply measured shifts of Raman-active modes to confirm lattice strain modification of both the out-of-plane and in-plane phonon vibrations of the MoS2 nanosheets. The induced band gap evolution due to in-plane and out-of-plane tensile stresses is validated by photoluminescence (PL) measurements, promising a potential route for unprecedented manipulation of the physical, electrical and optical properties of MoS2
Pan-Arctic landāatmospheric fluxes of methane and carbon dioxide in response to climate change over the 21st century
Future changes of pan-Arctic landāatmospheric methane (CH[subscript 4]) and carbon dioxide (CO[subscript 2]) depend on how terrestrial ecosystems respond to warming climate. Here, we used a coupled hydrologyābiogeochemistry model to make our estimates of these carbon exchanges with two contrasting climate change scenarios (no-policy versus policy) over the 21st century, by considering (1) a detailed water table dynamics and (2) a permafrost-thawing effect. Our simulations indicate that, under present climate conditions, pan-Arctic terrestrial ecosystems act as a net greenhouse gas (GHG) sink of ā0.2 Pg CO[subscript 2]-eq. yr[superscript ā1], as a result of a CH[subscript 4] source (53 Tg CH4 yr[superscript ā1]) and a CO[subscript 2] sink (ā0.4 Pg C yr[superscript ā1]). In response to warming climate, both CH[subscript 4] emissions and CO[subscript 2] uptakes are projected to increase over the century, but the increasing rates largely depend on the climate change scenario. Under the non-policy scenario, the CH[subscript 4] source and CO[subscript 2] sink are projected to increase by 60% and 75% by 2100, respectively, while the GHG sink does not show a significant trend. Thawing permafrost has a small effect on GHG sink under the policy scenario; however, under the no-policy scenario, about two thirds of the accumulated GHG sink over the 21st century has been offset by the carbon losses as CH[subscript 4] and CO[subscript 2] from thawing permafrost. Over the century, nearly all CO[subscript 2]-induced GHG sink through photosynthesis has been undone by CH[subscript 4]-induced GHG source. This study indicates that increasing active layer depth significantly affects soil carbon decomposition in response to future climate change. The methane emissions considering more detailed water table dynamics continuously play an important role in affecting regional radiative forcing in the pan-Arctic.United States. Dept. of Energy. SciDAC Institute on Quantum Simulation of Materials and NanostructuresUnited States. Dept. of Energy (Abrupt Climate Change)United States. National Aeronautics and Space Administration (Land Use and Land Cover Change Program NASA-NNX09AI26G)United States. Dept. of Energy (DE-FG02-08ER64599)National Science Foundation (U.S.). Division of Information and Intelligent Systems (NSF-1028291)National Science Foundation (U.S.) (Carbon and Water in the Earth Program (NSF-0630319)United States. Dept. of Energy. Office of Biological and Environmental Research (Contract DE-AC02-05CH11231
Reusing Deep Neural Network Models through Model Re-engineering
Training deep neural network (DNN) models, which has become an important task
in today's software development, is often costly in terms of computational
resources and time. With the inspiration of software reuse, building DNN models
through reusing existing ones has gained increasing attention recently. Prior
approaches to DNN model reuse have two main limitations: 1) reusing the entire
model, while only a small part of the model's functionalities (labels) are
required, would cause much overhead (e.g., computational and time costs for
inference), and 2) model reuse would inherit the defects and weaknesses of the
reused model, and hence put the new system under threats of security attack. To
solve the above problem, we propose SeaM, a tool that re-engineers a trained
DNN model to improve its reusability. Specifically, given a target problem and
a trained model, SeaM utilizes a gradient-based search method to search for the
model's weights that are relevant to the target problem. The re-engineered
model that only retains the relevant weights is then reused to solve the target
problem. Evaluation results on widely-used models show that the re-engineered
models produced by SeaM only contain 10.11% weights of the original models,
resulting 42.41% reduction in terms of inference time. For the target problem,
the re-engineered models even outperform the original models in classification
accuracy by 5.85%. Moreover, reusing the re-engineered models inherits an
average of 57% fewer defects than reusing the entire model. We believe our
approach to reducing reuse overhead and defect inheritance is one important
step forward for practical model reuse.Comment: Accepted by ICSE'2
HB-net: Holistic bursting cell cluster integrated network for occluded multi-objects recognition
Within the realm of image recognition, a specific category of multi-label
classification (MLC) challenges arises when objects within the visual field may
occlude one another, demanding simultaneous identification of both occluded and
occluding objects. Traditional convolutional neural networks (CNNs) can tackle
these challenges; however, those models tend to be bulky and can only attain
modest levels of accuracy. Leveraging insights from cutting-edge neural science
research, specifically the Holistic Bursting (HB) cell, this paper introduces a
pioneering integrated network framework named HB-net. Built upon the foundation
of HB cell clusters, HB-net is designed to address the intricate task of
simultaneously recognizing multiple occluded objects within images. Various
Bursting cell cluster structures are introduced, complemented by an evidence
accumulation mechanism. Testing is conducted on multiple datasets comprising
digits and letters. The results demonstrate that models incorporating the HB
framework exhibit a significant enhancement in recognition accuracy
compared to models without the HB framework ( times, ).
Although in high-noise settings, standard CNNs exhibit slightly greater
robustness when compared to HB-net models, the models that combine the HB
framework and EA mechanism achieve a comparable level of accuracy and
resilience to ResNet50, despite having only three convolutional layers and
approximately of the parameters. The findings of this study offer
valuable insights for improving computer vision algorithms. The essential code
is provided at https://github.com/d-lab438/hb-net.git
Protein Kinase CĪ“ Suppresses Autophagy to Induce Kidney Cell Apoptosis in Cisplatin Nephrotoxicity
Nephrotoxicity is a major adverse effect in cisplatin chemotherapy, and renoprotective approaches are unavailable. Recent work unveiled a critical role of protein kinase CĪ“ (PKCĪ“) in cisplatin nephrotoxicity and further demonstrated that inhibition of PKCĪ“ not only protects kidneys but enhances the chemotherapeutic effect of cisplatin in tumors; however, the underlying mechanisms remain elusive. Here, we show that cisplatin induced rapid activation of autophagy in cultured kidney tubular cells and in the kidneys of injected mice. Cisplatin also induced the phosphorylation of mammalian target of rapamycin (mTOR), p70S6 kinase downstream of mTOR, and serine/threonine-protein kinase ULK1, a component of the autophagy initiating complex. In vitro, pharmacologic inhibition of mTOR, directly or through inhibition of AKT, enhanced autophagy after cisplatin treatment. Notably, in both cells and kidneys, blockade of PKCĪ“ suppressed the cisplatin-induced phosphorylation of AKT, mTOR, p70S6 kinase, and ULK1 resulting in upregulation of autophagy. Furthermore, constitutively active and inactive forms of PKCĪ“ respectively enhanced and suppressed cisplatin-induced apoptosis in cultured cells. In mechanistic studies, we showed coimmunoprecipitation of PKCĪ“ and AKT from lysates of cisplatin-treated cells and direct phosphorylation of AKT at serine-473 by PKCĪ“in vitro Finally, administration of the PKCĪ“ inhibitor rottlerin with cisplatin protected against cisplatin nephrotoxicity in wild-type mice, but not in renal autophagy-deficient mice. Together, these results reveal a pathway consisting of PKCĪ“, AKT, mTOR, and ULK1 that inhibits autophagy in cisplatin nephrotoxicity. PKCĪ“ mediates cisplatin nephrotoxicity at least in part by suppressing autophagy, and accordingly, PKCĪ“ inhibition protects kidneys by upregulating autophagy
- ā¦