14,427 research outputs found
Chemical bonding and mechanical properties of M2AC (M = Ti, V, Cr, A = Al, Si, P, S) ceramics from first-principles investigations
No full textMAX-phase carbides (M is an early transition metal, A is an A-group element) exhibit an interesting bonding characteristic of alternative stacking of strong M-C bonds and relatively weak M-A bonds in one direction. In the present first-principles total energy calculations, we establish the relationship between mechanical properties and electronic structure for ternary <i>M<sub>2</sub>AC</i> (M = Ti, V, Cr, A = Al, Si, P, S) carbides. By systematically tuning elements on the M and A sites, pronounced enhancements of bulk modulus, elastic stiffness, and ideal shear strength are achieved in V-containing <i>V<sub>2</sub>AC</i> (A = A1, Si, P, and S) carbides. It is suggested that tailoring on the A site is more efficient than on the M site in strengthening the mechanical properties of studied serial carbides. The results highlight a general trend for tailor-made mechanical properties of ternary <i>M<sub>2</sub>AC</i> carbides by control of chemical bonding
Chemically Peculiar A and F Stars with Enhanced s-process and Iron-peak Elements: Stellar Radiative Acceleration at Work
No full textWe present ⪆15,000 metal-rich ([Fe/H] > -0.2 dex) A and F stars whose surface abundances deviate strongly from solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by their high [Ba/Fe] abundance ratios ([Ba/Fe] > 1.0 dex) in the LAMOST DR5 spectra analyzed by Xiang et al. They are almost exclusively main-sequence and subgiant stars with T eff ⪆ 6300 K. Their distribution in the Kiel diagram (T eff-log g) traces a sharp border at low temperatures along a roughly fixed-mass trajectory (around 1.4 M o ̇) that corresponds to an upper limit in convective envelope mass fraction of around 10-4. Most of these stars exhibit distinctly enhanced abundances of iron-peak elements (Cr, Mn, Fe, Ni) but depleted abundances of Mg and Ca. Rotational velocity measurements from GALAH DR2 show that the majority of these stars rotate slower than typical stars in an equivalent temperature range. These characteristics suggest that they are related to the so-called Am/Fm stars. Their abundance patterns are qualitatively consistent with the predictions of stellar evolution models that incorporate radiative acceleration, suggesting they are a consequence of stellar internal evolution, particularly involving the competition between gravitational settling and radiative acceleration. These peculiar stars constitute 40% of the whole population of stars with mass above 1.5 M o ̇, affirming that "peculiar"photospheric abundances due to stellar evolution effects are a ubiquitous phenomenon for these intermediate-mass stars. This large sample of Ba-enhanced, chemically peculiar A/F stars with individual element abundances provides the statistics to test more stringently the mechanisms that alter the surface abundances in stars with radiative envelopes
The Erdös-Sós Conjecture for Short-leg Spiders
No full text圖論中有關極值理論的 Erdos-Gallai 定理： n 個頂點的圖如果包含超過 (k-1)n/2 個邊，則其必包含一個 k 邊的路。根據這項結論， Erdos以及 Sos 猜測在相同的條件下，這樣的圖將會包含任何一個 k 邊的樹。蜘蛛圖，一種特別的樹，最多只能有一個頂點的度超過 2，這樣的頂點我們稱之為中心，其他的頂點的度為 1 或 2。一條從中心到度為 1 的頂點之路稱為蜘蛛圖的一隻腳。因此，
一條路即為一個一隻腳或兩隻腳的蜘蛛圖。在這篇論文中，我們將證明如果一 n 點的圖有超過 (k-1)n/2 個邊，那麼他將包含所有一隻腳長度為 5，其餘的腳長度都是 5 以下的 k 邊蜘蛛圖。另外，我們也證明如果一個 n 點的圖有超過 (k-1)n/2
個邊，且他有漢米爾頓圈，則其必包含任何 k 邊的蜘蛛圖。A classical result on extremal graph theory is the Erd˝os-Gallai Theorem: if a graph with n vertices has more than (k−1)n/2 edges, then it contains a path of k edges. Motivated by the result, Erd˝os and S´os conjectured that under the same condition, the graph should contain
every tree of k edges. A spider is a tree in which each vertex has degree 1 or 2, except for possibly one vertex, called the center of the spider. A leg of a spider is a path from the center to a vertex of degree one.
Thus, a path is a spider of 1 or 2 legs. In this thesis, we prove that if a graph with n vertices has more than (k−1)n/2 edges, then it contains every k-edge spider whose legs are of length at most 4 except exactly one is of length 5. In addition, we also prove that a Hamiltonian graph with n vertices and more than (k−1)n/2 edges contains every spider of k edges.Contents
Abstract in Chinese i
Abstract in English ii
1 Introduction 1
2 Spiders in Hamiltonian Cycle 4
3 Short-leg Spiders 5
References 1
Hemiasterlin derivative (R)(S)(S)-BF65 and Akt inhibitor MK-2206 synergistically inhibit SKOV3 ovarian cancer cell growth
No full textWe reported previously that a hemiasterlin derivative BF65 is a potent anticancer agent that can inhibit microtubule assembly. Here we show that a more potent stereospecific diastereomer (R)(S)(S)-BF65 can synergize with an allosteric Akt inhibitor MK-2206 to suppress the growth of SKOV3 ovarian cancer cells with constitutively active Akt. (R)(S)(S)-BF65 induced mitotic arrest and MK-2206 caused G0/G1 arrest, while the combination of both induced simultaneous G0/G1 and G2/M cell cycle arrest. (R)(S)(S)-BF65 induced phosphorylation and inactivation of Bcl-2, and downregulated Mcl-1, consequently may lead to apoptosis. (R)(S)(S)-BF65 inhibited mitogen-activated protein kinases (MAPKs), which may stimulate cell proliferation upon activation. (R)(S)(S)-BF65 also induced DNA damage after long-term treatment. MK-2206 is known to inhibit phosphorylation and activation of Akt and suppress cancer cell growth. The combination of (R)(S)(S)-BF65 and MK-2206 also inhibited the Akt pathway. Interestingly, MK-2206 upregulated Bcl-2 and induced activation of MAPKs in SKOV3 cells; however, when combined with (R)(S)(S)-BF65, these prosurvival effects were reversed. The combination also more significantly decreased Mcl-1 protein, increased PARP cleavage, and induced gamma-H2AX, a DNA damage marker. Remarkably, MK-2206 enhanced the microtubule depolymerization effect of (R)(S)(S)-BF65. The combination of (R)(S)(S)-BF65 and MK-2206 also markedly inhibited cell migration. Thus, MK-2206 synergizes with (R)(S)(S)-BF65 to inhibit SKOV3 cell growth via downregulating the Akt signaling pathway, and enhancing the microtubule disruption effect of (R)(S)(S)-BF65. (R)(S)(S)-BF65 in turn suppresses Bcl-2 and MAPKs induced by MK-2206. (R)(S)(S)-BF65 and MK-2206 compensate each other leading to increased apoptosis and enhanced cytotoxicity, and may also suppress cancer cell invasion. (C) 2016 Elsevier Inc. All rights reserved
Development of InP DHBT for 5G millimeter-wave power amplifier and GaAs photodetector for 50 Gb/s optical link
Get PDFThe high-speed optical transceivers require high-speed photodetector to be paired with high-speed vertical-cavity surface-emitting lasers (VCSELs) for short-range transmission at 850 nm. High-speed photodetector holds the key to higher data rate and lower energy consumption, which can help resolve the rising data traffic with high power efficiency. As for wireless communication, Indium phosphide (InP) heterojunction bipolar transistors (HBTs) are widely deployed in high-speed mixed signaling and radio-frequency (RF) instruments because of their outstanding ability to amplify the signals at high-speed bandwidth. Moreover, inherent material properties of InP such as high durability of the breakdown field and fast electron drift velocity make this material one of the suitable candidates when it comes to power amplifier applications within millimeter-wave spectrums. In this work, the development of the 50 Gb/s P-i-N photodetector Type-II InP DHBT for 5G power amplifier application will be presented and discussed. The development work of the photodetector includes the design consideration and process optimization, the dark current and bandwidth characterization of the fabricated device, followed by the impulse response measurement and microwave modeling. The development of Type-II InP DHBT consists of the review of the previous InP DHBT works at UIUC, plasma-enhanced InP dry-etching process development, DC and small-signal characterization, physical parameter extraction and ADS microwave modeling.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-08-01The student, Yu-Ting Peng, accepted the attached license on 2021-06-30 at 19:00.The student, Yu-Ting Peng, submitted this Dissertation for approval on 2021-06-30 at 19:20.This Dissertation was approved for publication on 2021-07-01 at 17:47.DSpace SAF Submission Ingestion Package generated from Vireo submission #16741 on 2022-01-12 at 12:52:48Made available in DSpace on 2022-01-12T22:34:50Z (GMT). No. of bitstreams: 2
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Hemiasterlin derivative (R)(S)(S)-BF65 and Akt inhibitor MK-2206 synergistically inhibit SKOV3 ovarian cancer cell growth
No full textWe reported previously that a hemiasterlin derivative BF65 is a potent anticancer agent that can inhibit microtubule assembly. Here we show that a more potent stereospecific diastereomer (R)(S)(S)-BF65 can synergize with an allosteric Akt inhibitor MK-2206 to suppress the growth of SKOV3 ovarian cancer cells with constitutively active Akt. (R)(S)(S)-BF65 induced mitotic arrest and MK-2206 caused G0/G1 arrest, while the combination of both induced simultaneous G0/G1 and G2/M cell cycle arrest. (R)(S)(S)-BF65 induced phosphorylation and inactivation of Bcl-2, and downregulated Mcl-1, consequently may lead to apoptosis. (R)(S)(S)-BF65 inhibited mitogen-activated protein kinases (MAPKs), which may stimulate cell proliferation upon activation. (R)(S)(S)-BF65 also induced DNA damage after long-term treatment. MK-2206 is known to inhibit phosphorylation and activation of Akt and suppress cancer cell growth. The combination of (R)(S)(S)-BF65 and MK-2206 also inhibited the Akt pathway. Interestingly, MK-2206 upregulated Bcl-2 and induced activation of MAPKs in SKOV3 cells; however, when combined with (R)(S)(S)-BF65, these prosurvival effects were reversed. The combination also more significantly decreased Mcl-1 protein, increased PARP cleavage, and induced γ-H2AX, a DNA damage marker. Remarkably, MK-2206 enhanced the microtubule depolymerization effect of (R)(S)(S)-BF65. The combination of (R)(S)(S)-BF65 and MK-2206 also markedly inhibited cell migration. Thus, MK-2206 synergizes with (R)(S)(S)-BF65 to inhibit SKOV3 cell growth via downregulating the Akt signaling pathway, and enhancing the microtubule disruption effect of (R)(S)(S)-BF65. (R)(S)(S)-BF65 in turn suppresses Bcl-2 and MAPKs induced by MK-2206. (R)(S)(S)-BF65 and MK-2206 compensate each other leading to increased apoptosis and enhanced cytotoxicity, and may also suppress cancer cell invasion
Grouping points by shared subspaces for effective subspace clustering
Get PDFClusters may exist in different subspaces of a multidimensional dataset. Traditional full-space clustering algorithms have difficulty in identifying these clusters. Various subspace clustering algorithms have used different subspace search strategies. They require clustering to assess whether cluster(s) exist in a subspace. In addition, all of them perform clustering by measuring similarity between points in the given feature space. As a result, the subspace selection and clustering processes are tightly coupled. In this paper, we propose a new subspace clustering framework named CSSub (Clustering by Shared Subspaces). It enables neighbouring core points to be clustered based on the number of subspaces they share. It explicitly splits candidate subspace selection and clustering into two separate processes, enabling different types of cluster definitions to be employed easily. Through extensive experiments on synthetic and real-world datasets, we demonstrate that CSSub discovers non-redundant subspace clusters with arbitrary shapes in noisy data; and it significantly outperforms existing state-of-the-art subspace clustering algorithms
Search for the Fundamental Structure of the Universe
No full text(This information was taken from the Distinguished Scientist Lecture Series Program 1982-1983).
Dr. Ting, Nobel laureate and Thomas Dudley Cabot Institute Professor at Massachusetts Institute of Technology, was born in Ann Arbor, Michigan. He attended the University of Michigan where he received a B . S. E. degree in 1959, an M .S. degree in 1960, and a Ph.D. degree in 1962.
In 1976, Dr. Ting was named co-recipient of the Nobel Prize in Physics with Dr. Burton Richter. Before joining MIT in 1967, Dr. Ting was a Ford Fellow at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland in 1963. He taught at Columbia University from 1964 to 1967, and served as group leader at Deutsche Electronen Synchrotron (DESY) in Hamburg, Germany in 1966. In 1970, Dr. Ting served in the Division of Particle and Fields of the American Physical Society, and was Associate Editor of Nuclear Physics B.
He was elected a Fellow of the American Academy of Art and Sciences in 1975, and became an Academia Sinica Fellow in 1976. Dr. Ting was honored with the Ernest Orlando Lawrence Award in 1976, and with the Eringen Medal of the Society of Engineering Science in 1977. He is a member of the National Academy of Sciences.
His Work: Dr. Ting and Dr. Richter, working in separate groups , electrified the world of high energy physics in November of 1974 with the discovery of a new particle with remarkable properties. Dr. Ting, in collaboration with teams from MIT and Brookhaven National Laboratory, was studying production of an electron in conjunction with its antiparticle -the positron-in protron-nucleon collisions at Brookhaven. His group found a remarkable yield of electron-positron pairs of rest energy 3. 1 Gev ( gigaelectron or one billion electron volts), indicating the production of a new particle, which they named J. Dr. Richter\u27s collaboration, Stanford Linear Accelerator Center-Lawrence Berkeley Laboratory, meanwhile, was studying at the same time the reverse process, discovering the same new particle which they named 4J . The implications of the e experiment continue to stimulate reformulation of our basic undersranding of matter.
His Lecture: October 16, 1982: Search for the Fundamental Structure of the Universe.https://digitalcommons.bard.edu/dsls_1982_1983/1006/thumbnail.jp
Healthcare resource utilization and costs of nonalcoholic steatohepatitis patients with advanced liver disease in Italy
No full textBackground and aims: Nonalcoholic steatohepatitis (NASH) may progress to advanced liver disease (AdvLD). This study characterized comorbidities, healthcare resource utilization (HCRU) and associated costs among hospitalized patients with AdvLD due to NASH in Italy. Methods and results: Adult nonalcoholic fatty liver disease (NAFLD)/NASH patients from 2011 to 2017 were identified from administrative databases of Italian local health units using ICD-9-CM codes. Development of compensated cirrhosis (CC), decompensated cirrhosis (DCC), hepatocellular carcinoma (HCC), or liver transplant (LT) was identified using first diagnosis date for each severity cohort (index-date). Patients progressing to multiple disease stages were included in >1 cohort. Patients were followed from index-date until the earliest of disease progression, end of coverage, death, or end of study. Within each cohort, per member per month values were annualized to calculate all-cause HCRU or costs(€) in 2017. Of the 9,729 hospitalized NAFLD/NASH patients identified, 97% were without AdvLD, 1.3% had CC, 3.1% DCC, 0.8% HCC, 0.1% LT. Comorbidity burden was high across all cohorts. Mean annual number of inpatient services was greater in patients with AdvLD than without AdvLD. Similar trends were observed in outpatient visits and pharmacy fills. Mean total annual costs increased with disease severity, driven primarily by inpatient services costs. Conclusion: NAFLD/NASH patients in Italy have high comorbidity burden. AdvLD patients had significantly higher costs. The higher prevalence of DCC compared to CC in this population may suggest challenges of effectively screening and identifying NAFLD/NASH patients. Early identification and effective management are needed to reduce risk of disease progression and subsequent HCRU and costs
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