126 research outputs found
Quantifying the efficiency of price-only contracts in push supply chains over demand distributions of known supports
In this paper, we quantify the efficiency of price-only contracts in supply chains with demand distributions by imposing prior knowledge only on the support, namely, those distributions with support [a, b] for 0 < a <_ b < +1. By characterizing the price of anarchy (PoA) under various push supply chain configurations, we enrich the application scope of the PoA concept in supply chain contracts along with complementary managerial insights. One of our major findings is that our quantitative analysis can identify scenarios where the price-only contract actually maintains its efficiency, namely, when the demand uncertainty, measured by the relative range b/a, is relatively low, entailing the price-only contract to be more attractive in this regard
Rank Based Tests for High Dimensional White Noise
The development of high-dimensional white noise test is important in both
statistical theories and applications, where the dimension of the time series
can be comparable to or exceed the length of the time series. This paper
proposes several distribution-free tests using the rank based statistics for
testing the high-dimensional white noise, which are robust to the heavy tails
and do not quire the finite-order moment assumptions for the sample
distributions. Three families of rank based tests are analyzed in this paper,
including the simple linear rank statistics, non-degenerate U-statistics and
degenerate U-statistics. The asymptotic null distributions and rate optimality
are established for each family of these tests. Among these tests, the test
based on degenerate U-statistics can also detect the non-linear and
non-monotone relationships in the autocorrelations. Moreover, this is the first
result on the asymptotic distributions of rank correlation statistics which
allowing for the cross-sectional dependence in high dimensional data
Asymptotic Independence of the Quadratic form and Maximum of Independent Random Variables with Applications to High-Dimensional Tests
This paper establishes the asymptotic independence between the quadratic form
and maximum of a sequence of independent random variables. Based on this
theoretical result, we find the asymptotic joint distribution for the quadratic
form and maximum, which can be applied into the high-dimensional testing
problems. By combining the sum-type test and the max-type test, we propose the
Fisher's combination tests for the one-sample mean test and two-sample mean
test. Under this novel general framework, several strong assumptions in
existing literature have been relaxed. Monte Carlo simulation has been done
which shows that our proposed tests are strongly robust to both sparse and
dense data
Stacking tunable interlayer magnetism in bilayer CrI3
Diverse interlayer tunability of physical properties of two-dimensional
layers mostly lies in the covalent-like quasi-bonding that is significant in
electronic structures but rather weak for energetics. Such characteristics
result in various stacking orders that are energetically comparable but may
significantly differ in terms of electronic structures, e.g. magnetism.
Inspired by several recent experiments showing interlayer
anti-ferromagnetically coupled CrI3 bilayers, we carried out first-principles
calculations for CrI3 bilayers. We found that the anti-ferromagnetic coupling
results from a new stacking order with the C2/m space group symmetry, rather
than the graphene-like one with R3 as previously believed. Moreover, we
demonstrated that the intra- and inter-layer couplings in CrI3 bilayer are
governed by two different mechanisms, namely ferromagnetic super-exchange and
direct-exchange interactions, which are largely decoupled because of their
significant difference in strength at the strong- and weak-interaction limits.
This allows the much weaker interlayer magnetic coupling to be more feasibly
tuned by stacking orders solely. Given the fact that interlayer magnetic
properties can be altered by changing crystal structure with different stacking
orders, our work opens a new paradigm for tuning interlayer magnetic properties
with the freedom of stacking order in two dimensional layered materials
Topotactic-hydrogen forms chains in O nickelate superconductors
Despite enormous experimental and theoretical efforts, obtaining generally
accepted conclusions regarding the intrinsic magnetic and electronic properties
of superconducting nickelates remains exceptionally challenging. Experiments
show a significant degree of uncertainty, indicating hidden factors in the
synthesized films, which call for further investigations. One of those "hidden
factors" is the possibility of intercalating hydrogen during the chemical
reduction process from Nd(La)NiO to Nd(La)NiO using CaH. While
hydrogen has been detected in experimental samples, not much is known about its
distribution through the crystal and its influence on the electronic
environment. Here, we show the tendency toward the formation of one-dimensional
hydrogen chains in infinite-layers LaNiO superconductors using
density-functional theory (DFT) supplemented by dynamical mean-field theory
(DMFT). The formation of such hydrogen chains induces a coexistence of
different oxidation states of Ni and competing magnetic phases, and possibly
explains the recently observed charge order states in nickelate
superconductors. Furthermore, it contributes to the difficulty of synthesizing
homogeneous nickelates and determining their ground states. The smoking gun to
detect excess hydrogen in nickelates are flat phonon modes, which are infrared
active and quite insensitive to the exact arrangement of the H atoms.Comment: 19 pages, 13 figures, under PRB revie
Effect of low-intensity transcranial ultrasound stimulation on theta and gamma oscillations in the mouse hippocampal CA1
Previous studies have demonstrated that low-intensity transcranial ultrasound stimulation (TUS) can eliminate hippocampal neural activity. However, until now, it has remained unclear how ultrasound modulates theta and gamma oscillations in the hippocampus under different behavioral states. In this study, we used ultrasound to stimulate the CA1 in mice in anesthesia, awake and running states, and we simultaneously recorded the local field potential of the stimulation location. We analyzed the power spectrum, phase-amplitude coupling (PAC) of theta and gamma oscillations, and their relationship with ultrasound intensity. The results showed that (i) TUS significantly enhanced the absolute power of theta and gamma oscillations under anesthesia and in the awake state. (ii) The PAC strength between theta and gamma oscillations is significantly enhanced under the anesthesia and awake states but is weakened under the running state with TUS. (iii) Under anesthesia, the relative power of theta decreases and that of gamma increases as ultrasound intensity increases, and the result under the awake state is opposite that under the anesthesia state. (iv) The PAC index between theta and gamma increases as ultrasound intensity increases under the anesthesia and awake states. The above results demonstrate that TUS can modulate theta and gamma oscillations in the CA1 and that the modulation effect depends on behavioral states. Our study provides guidance for the application of ultrasound in modulating hippocampal function
Complete Sequence of a F33:A-:B- Conjugative Plasmid Carrying the oqxAB, fosA3, and blaCTX-M-55 Elements from a Foodborne Escherichia coli Strain
This study reports the complete sequence of pE80, a conjugative IncFII plasmid recovered from an Escherichia coli strain isolated from chicken meat. This plasmid harbors multiple resistance determinants including oqxAB, fosA3, blaCTX-M-55, and blaTEM-1, and is a close variant of the recently reported p42-2 element, which was recovered from E. coli of veterinary source. Recovery of pE80 constitutes evidence that evolution or genetic re-arrangement of IncFII type plasmids residing in animal-borne organisms is an active event, which involves acquisition and integration of foreign resistance elements into the plasmid backbone. Dissemination of these plasmids may further compromise the effectiveness of current antimicrobial strategies.Department of Applied Biology and Chemical Technolog
Scoring System for Tumor-Infiltrating Lymphocytes and Its Prognostic Value for Gastric Cancer
The tumor microenvironment (TME) is the internal environment of malignant tumor progression, and the host antitumor immune response and normal tissue destruction occur in the TME. Tumor-infiltrating lymphocytes (TIL) is a crucial component of the TME and reflect the host antitumor immune response. The purpose of this study was to discuss the methodology for TIL evaluation and assess the prognostic value of TIL in gastric cancer. In total, we reviewed 1,033 gastrectomy cases between 2002 and 2008 at the Third Affiliated Hospital of Soochow University. To understand the prognostic value of TIL in gastric cancer (GC), TIL were assessed by optical microscopy, and verified by immunohistochemistry. There is no current consensus on TIL scoring in GC. In this study, we discussed a TIL evaluation system that includes an analysis of the amount and percentage of TIL in a tumor. Ultimately, 439 (52.7%) cases showed high levels of TIL and 394 (47.3%) cases had low levels. There was a statistically significant relationship among TIL, tumor size, histological grade, LN metastasis, nerve invasion, tumor thrombus, pTN stage, and WHO subtypes (p < 0.001, respectively). TILhi was a positive significant predictor of overall survival (OS) in KaplanāMeier survival analysis (P < 0.001) and multivariate Cox regression analysis (HR = 0.431, 95% CI: 0.347ā0.534, P < 0.001). After surgery, patients with malignant tumors underwent chemoradiotherapy according to standard therapeutic guidelines based on TNM stage. The TNM scoring system cannot reflect the full information of TME; therefore, TIL can be used as a diagnostic supplement. We constructed a nomogram model that showed more predictive accuracy for OS than pTN stage. In summary, this study proves that high levels of TIL are associated with a positive prognosis and that TIL reflect the protective host antitumor immune response
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