1,055 research outputs found
Provenance evolution of ageâcalibrated strata reveals when and how South China Block collided with Gondwana
The South China Block (SCB) has been regarded by many as an integral part of Gondwana, but proposed timing and processes for its accretion to Gondwana vary and remain contentious, largely owing to the lack of reliable PanâAfrican age paleomagnetic data and tectonoâmagmatic records from the SCB. Integrated in situ UâPb ages and HfâO isotope analyses of detrital zircons from geochronologically wellâcalibrated EdiacaranâCambrian sedimentary rocks of western SCB reveal age populations of 2.51, 1.85, 1.20, 0.80, and 0.52 Ga. Detrital zircon age spectra indicate a major tectonic transition for the SCB during 0.56â0.54 Ga, interpreted to reflect the beginning of the collision between SCBâIndochina and NW India blocks. The collisional event lasted until early Ordovician, leading to the suturing of the SCBâIndochina to the northern margin of East Gondwana
Evolving IT Organizational Identity as a Source of IT-enabled Enterprise Agility in China
Prior research has proposed that IT may hinder the attainment of enterprise agility; how to prevent this hindrance and further achieve IT-enabled enterprise agility remains unknown. Because IT organizational identity can be an important guidepost for eliminating the hindrance, the purpose of this paper is to explore how to achieve IT-enabled enterprise agility through an evolving IT organizational identity. By drawing upon recent thinking in the enterprise agility and organizational identity literature, this paper proposes a process model of IT organizational identity evolution to argue that the process of recreating an IT identity leads an enterprise to attain IT-enabled agility. In the present study, the case of Chinaâs Haier Group is comprehensively analyzed based on the process model. Our study not only contributes to the knowledge of organizational identity and broader concepts of enterprise agility, but also provides useful means for practitioners to establish appropriate IT organizational identities over time
Neutron star phase transition as the origin for the fast radio bursts and soft gamma-ray repeaters of SGR J1935+2154
Magnetars are believed as neutron stars (NSs) with strong magnetic fields.
X-ray flares and fast radio bursts (FRBs) have been observed from the magnetar
(soft gamma-ray repeater, SGR J1935+2154). We propose that the phase transition
of the NS can power the FRBs and SGRs.Based on the equation of state provided
by the MIT bag model and the mean field approximation, we solve the
Tolman-Oppenheimer-Volkoff equations to get the NS structure. With spin-down of
the NS, the hadronic shell gradually transfers to the quark shell.The
gravitational potential energy released by one time of the phase transition can
be achieved. The released energy, time interval between two successive phase
transitions, and glitch are all consistent with the observations of the FRBs
and the X-ray flares from SGR J1935+2154. We conclude that the phase transition
of an NS is a plausible mechanism to power the SGRs as well as the repeating
FRBs.Comment: 11 pages, 3 figure
What Differs on the Enzymatic Acetylation Mechanisms for Arylamines and Arylhydrazines Substrates? A Theoretical Study
The acetylation mechanisms of several selected typical substrates from experiments, including arylamines and arylhydrazines, are investigated with the density functional theory in this paper. The results indicate that all the transition states are characterized by a four-membered ring structure, and hydralazine (HDZ) is the most potent substrate. The bioactivity for all the compounds is increased in a sequence of PABA â 4-AS < 4-MA < 5-AS â INH < HDZ. The conjunction effect and the delocalization of the lone pairs of N atom play a key role in the reaction. All the results are consistent with the experimental data
Dynamic diffusion tensor imaging reveals structural changes in the bilateral pyramidal tracts after brain stem hemorrhage in rats
Background and Purpose: Few studies have concentrated on pyramidal tract (PY) changes after brain stem hemorrhage (BSH). In this study, we used a diffusion tensor imaging (DTI) technique and histologic identification to investigate longitudinal PY changes on both the contralateral and ipsilateral sides after experimental BSH. Methods: BSH was induced in 61 Sprague-Dawley rats by infusing 30 ÎŒl of autogenous tail blood into each ratâs right pons. DTI and motor function examinations were performed repeatedly on days 1, 3, 7, 14, and 28 after surgery. Fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were measured in the bilateral PYs. The axon and myelin injury in the PY were evaluated by histologic study. Results: As compared with normal controls, the bilateral PYs in rats with induced BSH showed an early decrease and a late increase in fractional anisotropy and an early increase and a late decrease in mean diffusivity. A progressive decrease in axial diffusivity with dramatic axon loss from day 1 to day 28 after BSH was found bilaterally. The bilateral PYs showed an early increase and a late decrease in radial diffusivity. Early myelin injury and late repair were also detected pathologically in the bilateral PYs of rats with BSH. Thus, the early motor function deficits of rats with BSH began to improve on day 14 and had almost completely disappeared by day 28. Conclusions: DTI revealed dynamic changes in the bilateral PYs after BSH, which was confirmed by histologic findings and which correlated with motor function alteration. These findings support the idea that quantitative DTI can track structural changes in the bilateral PYs and that DTI may serve as a noninvasive tool to predict the prognoses of patients with BSH
Imaging characterization of myocardial function, fibrosis, and perfusion in a nonhuman primate model with heart failure-like features
INTRODUCTION: The availability of a human-like chronic heart failure (HF) animal model was critical for affiliating development of novel therapeutic drug treatments. With the close physiology relatedness to humans, the non-human primate (NHP) HF model would be valuable to better understand the pathophysiology and pharmacology of HF. The purpose of this work was to present preliminary cardiac image findings using echocardiography and cardiovascular magnetic resonance (CMR) in a HF-like cynomolgus macaque model.
METHODS: The NHP diet-induced model developed cardiac phenotypes that exhibited diastolic dysfunction with reduced left ventricular ejection fraction (LVEF) or preserved LVEF. Twenty cynomolgus monkeys with cardiac dysfunction were selected by echocardiography and subsequently separated into two groups, LVEFâ\u3câ65% (termed as HFrEF,
RESULTS: No LGE was observed in any monkey. Monkeys with HF-like features were significantly older, compared to the healthy control group. There were significant differences among the three groups in ECV (20.79â±â3.65% in healthy controls; 27.06â±â3.37% in HFpEF group, and 31.11â±â4.50% in HFrEFgroup,
CONCLUSION: Our preliminary imaging findings demonstrated cardiac dysfunction, elevated ECV, and/or reduced MPR in this HF-like NHP model. This pilot study laid the foundation for further mechanistic research and the development of a drug testing platform for distinct HF pathophysiology
Beimingwu: A Learnware Dock System
The learnware paradigm proposed by Zhou [2016] aims to enable users to reuse
numerous existing well-trained models instead of building machine learning
models from scratch, with the hope of solving new user tasks even beyond
models' original purposes. In this paradigm, developers worldwide can submit
their high-performing models spontaneously to the learnware dock system
(formerly known as learnware market) without revealing their training data.
Once the dock system accepts the model, it assigns a specification and
accommodates the model. This specification allows the model to be adequately
identified and assembled to reuse according to future users' needs, even if
they have no prior knowledge of the model. This paradigm greatly differs from
the current big model direction and it is expected that a learnware dock system
housing millions or more high-performing models could offer excellent
capabilities for both planned tasks where big models are applicable; and
unplanned, specialized, data-sensitive scenarios where big models are not
present or applicable.
This paper describes Beimingwu, the first open-source learnware dock system
providing foundational support for future research of learnware paradigm.The
system significantly streamlines the model development for new user tasks,
thanks to its integrated architecture and engine design, extensive engineering
implementations and optimizations, and the integration of various algorithms
for learnware identification and reuse. Notably, this is possible even for
users with limited data and minimal expertise in machine learning, without
compromising the raw data's security. Beimingwu supports the entire process of
learnware paradigm. The system lays the foundation for future research in
learnware-related algorithms and systems, and prepares the ground for hosting a
vast array of learnwares and establishing a learnware ecosystem
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