434 research outputs found
Coding scheme for 3D vertical flash memory
Recently introduced 3D vertical flash memory is expected to be a disruptive
technology since it overcomes scaling challenges of conventional 2D planar
flash memory by stacking up cells in the vertical direction. However, 3D
vertical flash memory suffers from a new problem known as fast detrapping,
which is a rapid charge loss problem. In this paper, we propose a scheme to
compensate the effect of fast detrapping by intentional inter-cell interference
(ICI). In order to properly control the intentional ICI, our scheme relies on a
coding technique that incorporates the side information of fast detrapping
during the encoding stage. This technique is closely connected to the
well-known problem of coding in a memory with defective cells. Numerical
results show that the proposed scheme can effectively address the problem of
fast detrapping.Comment: 7 pages, 9 figures. accepted to ICC 2015. arXiv admin note: text
overlap with arXiv:1410.177
Electronic and phonon excitations in {\alpha}-RuCl
We report on THz, infrared reflectivity and transmission experiments for wave
numbers from 10 to 8000 cm ( 1 meV - 1 eV) and for temperatures
from 5 to 295 K on the Kitaev candidate material {\alpha}-RuCl. As reported
earlier, the compound under investigation passes through a first-order
structural phase transition, from a monoclinic high-temperature to a
rhombohedral low-temperature phase. The phase transition shows an extreme and
unusual hysteretic behavior, which extends from 60 to 166 K. In passing this
phase transition, in the complete frequency range investigated we found a
significant reflectance change, which amounts almost a factor of two. We
provide a broadband spectrum of dielectric constant, dielectric loss and
optical conductivity from the THz to the mid infrared regime and study in
detail the phonon response and the low-lying electronic density of states. We
provide evidence for the onset of an optical energy gap, which is of order 200
meV, in good agreement with the gap derived from measurements of the DC
electrical resistivity. Remarkably, the onset of the gap exhibits a strong blue
shift on increasing temperatures.Comment: 18 pages, 7 figure
Multi-kilowatt single-mode ytterbium-doped large-core fiber laser
We have demonstrated a highly efficient cladding-pumped ytterbium-doped fiber laser, generating >2.1 kW of continuous-wave output power at 1.1 µm with 74% slope efficiency with respect to launched pump power. The beam quality factor (M2) was better than 1.2. The maximum output power was only limited by available pump power, showing no evidence of roll-over even at the highest output power. We present data on how the beam quality depends on the fiber parameter, based on our current and past fiber laser developments. We also discuss the ultimate power-capability of our fiber in terms of thermal management, Raman nonlinear scattering, and material damage, and estimate it to 10 k
Delayed surgical intervention in central cord syndrome with cervical stenosis
Study Design Review of the literature. Objective It is generally accepted that surgical treatment is necessary for central cord syndrome (CCS) with an underlying cervical stenosis. However, the surgical timing for decompression is controversial in spondylotic cervical CCS. The purpose of this study is to review the results of early and delayed surgery in patients with spondylotic cervical CCS. Methods MEDLINE was searched for English-language articles on CCS. There were 1,653 articles from 1940 to 2012 regarding CCS, 5 of which dealt with the timing of surgery for spondylotic cervical CCS. Results All five reports regarding the surgical timing of spondylotic cervical CCS were retrospective. Motor improvement, functional independence measures, and walking ability showed similar improvement in early and late surgery groups in the studies with follow-up longer than 1 year. However, greater improvement was seen in the early surgery group in the studies with follow-up shorter than 1 year. The complication rates did not show a difference between the early and late surgery groups. However, there are controversies regarding the length of intensive care unit stay or hospital stay for the two groups. Conclusions There was no difference in motor improvement, functional independence, walking ability, and complication rates between early and late surgery for spondylotic cervical CCS
Sub-gap optical response across the structural phase transition in van der Waals layered \alpha-RuCl
We report magnetic, thermodynamic, thermal expansion, and on detailed optical
experiments on the layered compound -RuCl focusing on the THz and
sub-gap optical response across the structural phase transition from the
monoclinic high-temperature to the rhombohedral low-temperature structure,
where the stacking sequence of the molecular layers is changed. This type of
phase transition is characteristic for a variety of tri-halides crystallizing
in a layered honeycomb-type structure and so far is unique, as the
low-temperature phase exhibits the higher symmetry. One motivation is to
unravel the microscopic nature of spin-orbital excitations via a study of
temperature and symmetry-induced changes. We document a number of highly
unusual findings: A characteristic two-step hysteresis of the structural phase
transition, accompanied by a dramatic change of the reflectivity. An electronic
excitation, which appears in a narrow temperature range just across the
structural phase transition, and a complex dielectric loss spectrum in the THz
regime, which could indicate remnants of Kitaev physics. Despite significant
symmetry changes across the monoclinic to rhombohedral phase transition, phonon
eigenfrequencies and the majority of spin-orbital excitations are not strongly
influenced. Obviously, the symmetry of the single molecular layers determine
the eigenfrequencies of most of these excitations. Finally, from this combined
terahertz, far- and mid-infrared study we try to shed some light on the so far
unsolved low energy (< 1eV) electronic structure of the ruthenium
electrons in -RuCl.Comment: 22 pages, 9 figure
An Ontology-Based Collaborative Interorganizational Knowledge Management Network
Web contents can be represented in a structural form by a finite list of vocabularies and their relationships using ontologies. The concept of ontology and its related mediation methods is capable of enhancing the collaboration among Knowledge Management (KM) approaches that only focus on managing organizational knowledge. Those KM approaches are developed in accordance with organizational KM strategies and business requirements without the concern of system interoperation. In this research, an ontology-based collaborative inter-organizational KM network is proposed to provide a platform for organizations to access and retrieve inter-organizational knowledge in a similar domain
Tumor suppressive role of sestrin2 during colitis and colon carcinogenesis
The mTOR complex 1 (mTORC1) and endoplasmic reticulum (ER) stress pathways are critical regulators of intestinal inflammation and colon cancer growth. Sestrins are stress-inducible proteins, which suppress both mTORC1 and ER stress; however, the role of Sestrins in colon physiology and tumorigenesis has been elusive due to the lack of studies in human tissues or in appropriate animal models. In this study, we show that human SESN2 expression is elevated in the colon of ulcerative colitis patients but is lost upon p53 inactivation during colon carcinogenesis. In mouse colon, Sestrin2 was critical for limiting ER stress and promoting the recovery of epithelial cells after inflammatory injury. During colitis-promoted tumorigenesis, Sestrin2 was shown to be an important mediator of p53’s control over mTORC1 signaling and tumor cell growth. These results highlight Sestrin2 as a novel tumor suppressor, whose downregulation can accelerate both colitis and colon carcinogenesis
Machine learning algorithm to predict mortality in patients undergoing continuous renal replacement therapy
Abstract
Background
Previous scoring models such as the Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scoring systems do not adequately predict mortality of patients undergoing continuous renal replacement therapy (CRRT) for severe acute kidney injury. Accordingly, the present study applies machine learning algorithms to improve prediction accuracy for this patient subset.
Methods
We randomly divided a total of 1571 adult patients who started CRRT for acute kidney injury into training (70%, n = 1094) and test (30%, n = 477) sets. The primary output consisted of the probability of mortality during admission to the intensive care unit (ICU) or hospital. We compared the area under the receiver operating characteristic curves (AUCs) of several machine learning algorithms with that of the APACHE II, SOFA, and the new abbreviated mortality scoring system for acute kidney injury with CRRT (MOSAIC model) results.
Results
For the ICU mortality, the random forest model showed the highest AUC (0.784 [0.744–0.825]), and the artificial neural network and extreme gradient boost models demonstrated the next best results (0.776 [0.735–0.818]). The AUC of the random forest model was higher than 0.611 (0.583–0.640), 0.677 (0.651–0.703), and 0.722 (0.677–0.767), as achieved by APACHE II, SOFA, and MOSAIC, respectively. The machine learning models also predicted in-hospital mortality better than APACHE II, SOFA, and MOSAIC.
Conclusion
Machine learning algorithms increase the accuracy of mortality prediction for patients undergoing CRRT for acute kidney injury compared with previous scoring models
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