1,213 research outputs found

    Optimal group testing designs for estimating prevalence with uncertain testing errors

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    We construct optimal designs for group testing experiments where the goal is to estimate the prevalence of a trait by using a test with uncertain sensitivity and specificity. Using optimal design theory for approximate designs, we show that the most efficient design for simultaneously estimating the prevalence, sensitivity and specificity requires three different group sizes with equal frequencies. However, if estimating prevalence as accurately as possible is the only focus, the optimal strategy is to have three group sizes with unequal frequencies. On the basis of a chlamydia study in the U.S.A., we compare performances of competing designs and provide insights into how the unknown sensitivity and specificity of the test affect the performance of the prevalence estimator. We demonstrate that the locally D- and Ds-optimal designs proposed have high efficiencies even when the prespecified values of the parameters are moderately misspecified

    Quantum correlation generation capability of experimental processes

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    Einstein-Podolsky-Rosen (EPR) steering and Bell nonlocality illustrate two different kinds of correlations predicted by quantum mechanics. They not only motivate the exploration of the foundation of quantum mechanics, but also serve as important resources for quantum-information processing in the presence of untrusted measurement apparatuses. Herein, we introduce a method for characterizing the creation of EPR steering and Bell nonlocality for dynamical processes in experiments. We show that the capability of an experimental process to create quantum correlations can be quantified and identified simply by preparing separable states as test inputs of the process and then performing local measurements on single qubits of the corresponding outputs. This finding enables the construction of objective benchmarks for the two-qubit controlled operations used to perform universal quantum computation. We demonstrate this utility by examining the experimental capability of creating quantum correlations with the controlled-phase operations on the IBM Quantum Experience and Amazon Braket Rigetti superconducting quantum computers. The results show that our method provides a useful diagnostic tool for evaluating the primitive operations of nonclassical correlation creation in noisy intermediate scale quantum devices.Comment: 5 figures, 3 appendice

    Quasi-Hermitian extended SSH models

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    We consider the quasi Hermitian limit of a non-Hermitian extended Su Schrieffer Heeger model, in which the hopping amplitudes obey a specific relation so that the system may be mapped to a corresponding Hermitian one and its energy spectrum is completely real. Analogous to the Hermitian case, one may use the modified winding number to determine the total number of edge states on the boundaries to achieve a modified bulk-boundary correspondence. Due to the skin effect in nonHermitian systems, the spectral winding numbers must be used to classify such systems further. It dictates how the edge states would be distributed over the left and right boundaries. We then naively extend the criteria to the cases that the quasi Hermitian condition is violated. For all the cases that we consider, no inconsistency has been found.Comment: 21 pages, 10 figure

    Inhibition of Mitochondria- and Endoplasmic Reticulum Stress-Mediated Autophagy Augments Temozolomide-Induced Apoptosis in Glioma Cells

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    Autophagy is a crucial process for cells to maintain homeostasis and survival through degradation of cellular proteins and organelles, including mitochondria and endoplasmic reticula (ER). We previously demonstrated that temozolomide (TMZ), an alkylating agent for brain tumor chemotherapy, induced reactive oxygen species (ROS)/extracellular signal-regulated kinase (ERK)-mediated autophagy to protect glioma cells from apoptosis. In this study, we investigated the role of mitochondrial damage and ER stress in TMZ-induced cytotoxicity. Mitochondrial depolarization and mitochondrial permeability transition pore (MPTP) opening were observed as a prelude to TMZ-induced autophagy, and these were followed by the loss of mitochondrial mass. Electron transport chain (ETC) inhibitors, such as rotenone (a complex I inhibitor), sodium azide (a complex IV inhibitor), and oligomycin (a complex V inhibitor), or the MPTP inhibitor, cyclosporine A, decreased mitochondrial damage-mediated autophagy, and therefore increased TMZ-induced apoptosis. TMZ treatment triggered ER stress with increased expression of GADD153 and GRP78 proteins, and deceased pro-caspase 12 protein. ER stress consequently induced autophagy through c-Jun N-terminal kinases (JNK) and Ca2+ signaling pathways. Combination of TMZ with 4-phenylbutyrate (4-PBA), an ER stress inhibitor, augmented TMZ-induced cytotoxicity by inhibiting autophagy. Taken together, our data indicate that TMZ induced autophagy through mitochondrial damage- and ER stress-dependent mechanisms to protect glioma cells. This study provides evidence that agents targeting mitochondria or ER may be potential anticancer strategies

    Photoproducts of indomethacin exhibit decreased hydroxyl radical scavenging and xanthine oxidase inhibition activities

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    AbstractIndomethacin (IN) is a widely used nonsteroidal anti-inflammatory drug. In this study, four photoproducts of IN (IN1–IN4) were produced and isolated from photoirradiated IN. This study investigated the abilities of IN and its photoproducts to scavenge hydroxyl radicals and inhibit xanthine oxidase (XO). The hydroxyl radical-scavenging activity was measured in vitro by electron spin resonance spectrometry using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trapping agent. Enzyme activity was measured by continuous monitoring of uric acid formation, using xanthine as a substrate. The results showed that, among all the related products, IN has the strongest hydroxyl radical-scavenging (IC50 = 65 μM) and XO inhibitory (IC50 = 86 μM) effects. To further understand the stereochemistry of the reactions between these IN derivatives and XO, we performed computer-aided molecular modeling. IN was the most potent inhibitor with the most favorable interaction in the reactive site. Various photoproducts exhibited affinity toward XO as a result of the absence of hydrogen bonding with molybdopterin domain
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