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"Chang, S."
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Phonon-mediated quantum state transfer and remote qubit entanglement
Phonons, and in particular surface acoustic wave phonons, have been proposed as a means to coherently couple distant solid-state quantum systems. Individual phonons in a resonant structure can be controlled and detected by superconducting qubits, enabling the coherent generation and measurement of complex stationary phonon states. We report the deterministic emission and capture of itinerant surface acoustic wave phonons, enabling the quantum entanglement of two superconducting qubits. Using a 2-millimeter-long acoustic quantum communication channel, equivalent to a 500-nanosecond delay line, we demonstrate the emission and recapture of a phonon by one superconducting qubit, quantum state transfer between two superconducting qubits with a 67% efficiency, and, by partial transfer of a phonon, generation of an entangled Bell pair with a fidelity of 84%.
Journal Article
A systematic review of hybrid brain-computer interfaces: Taxonomy and usability perspectives
A new Brain-Computer Interface (BCI) technique, which is called a hybrid BCI, has recently been proposed to address the limitations of conventional single BCI system. Although some hybrid BCI studies have shown promising results, the field of hybrid BCI is still in its infancy and there is much to be done. Especially, since the hybrid BCI systems are so complicated and complex, it is difficult to understand the constituent and role of a hybrid BCI system at a glance. Also, the complicated and complex systems make it difficult to evaluate the usability of the systems. We systematically reviewed and analyzed the current state-of-the-art hybrid BCI studies, and proposed a systematic taxonomy for classifying the types of hybrid BCIs with multiple taxonomic criteria. After reviewing 74 journal articles, hybrid BCIs could be categorized with respect to 1) the source of brain signals, 2) the characteristics of the brain signal, and 3) the characteristics of operation in each system. In addition, we exhaustively reviewed recent literature on usability of BCIs. To identify the key evaluation dimensions of usability, we focused on task and measurement characteristics of BCI usability. We classified and summarized 31 BCI usability journal articles according to task characteristics (type and description of task) and measurement characteristics (subjective and objective measures). Afterwards, we proposed usability dimensions for BCI and hybrid BCI systems according to three core-constructs: Satisfaction, effectiveness, and efficiency with recommendations for further research. This paper can help BCI researchers, even those who are new to the field, can easily understand the complex structure of the hybrid systems at a glance. Recommendations for future research can also be helpful in establishing research directions and gaining insight in how to solve ergonomics and HCI design issues surrounding BCI and hybrid BCI systems by usability evaluation.
Journal Article
Quantum control of surface acoustic-wave phonons
One of the hallmarks of quantum physics is the generation of non-classical quantum states and superpositions, which has been demonstrated in several quantum systems, including ions, solid-state qubits and photons. However, only indirect demonstrations of non-classical states have been achieved in mechanical systems, despite the scientific appeal and technical utility of such a capability
1
,
2
, including in quantum sensing, computation and communication applications. This is due in part to the highly linear response of most mechanical systems, which makes quantum operations difficult, as well as their characteristically low frequencies, which hinder access to the quantum ground state
3
–
7
. Here we demonstrate full quantum control of the mechanical state of a macroscale mechanical resonator. We strongly couple a surface acoustic-wave
8
resonator to a superconducting qubit, using the qubit to control and measure quantum states in the mechanical resonator. We generate a non-classical superposition of the zero- and one-phonon Fock states and map this and other states using Wigner tomography
9
–
14
. Such precise, programmable quantum control is essential to a range of applications of surface acoustic waves in the quantum limit, including the coupling of disparate quantum systems
15
,
16
.
A non-classical superposition of zero- and one-phonon mechanical Fock states is generated and measured by strongly coupling a surface acoustic-wave resonator to a superconducting qubit.
Journal Article
Associations of urinary phthalates with body mass index, waist circumference and serum lipids among females: National Health and Nutrition Examination Survey 1999–2004
Background/objectives:
Exposure to environmental chemicals could be one of the contributors to the increasing obesity epidemic. Very little is known about the association of phthalates, ubiquitous chemicals widely used in consumer products, with obesity and lipid metabolism. This study investigated the association of urinary phthalate metabolites and, for the first time, the ratios of the major metabolites of the most common phthalate, di-2-ethylhexyl phthalate, with body mass index (BMI), waist circumference and serum lipid levels in the US female population.
Methods:
This cross-sectional study used the data from the National Health and Nutrition Examination Survey, 1999–2004 and was restricted to women aged ⩾18 years, who were not pregnant and had no history of diabetes. Using multivariate ordered logistic regression, we examined associations of seven urinary phthalate metabolites and their metabolic ratios with the BMI, waist circumferences, total cholesterol, triglycerides and high- and low-density lipoprotein cholesterol.
Results:
BMI was positively associated with monobutyl phthalate (MBP) and mono-2-ethylhexyl phthalate (MEHP) (odds ratio (OR)=1.13; 95% confidence interval (CI), 1.03–1.23 and OR=1.12; 95% CI, 1.03–1.23, respectively). Waist circumference was positively associated with MBP (OR=1.13; 95% CI, 1.03–1.24). A higher ratio of MEHP to mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was positively associated with both BMI (OR=1.21; 95% CI, 1.09–1.34) and waist circumference (OR=1.20; 95% CI, 1.10–1.31). There were no other significant associations.
Conclusions:
A higher metabolic ratio of MEHP to MEHHP, reflective of slower oxidative conversion of MEHP, is associated with greater BMI and waist circumference.
Journal Article
Aurora A kinase activates YAP signaling in triple-negative breast cancer
The Yes-associated protein (YAP) is an effector that transduces the output of the Hippo pathway to transcriptional modulation. Considering the role of YAP in cancers, this protein has emerged as a key node in malignancy development. In this study, we determined that Aurora A kinase acts as a positive regulator for YAP-mediated transcriptional machinery. Specifically, YAP associates with Aurora A predominantly in the nucleus. Activation of Aurora A can impinge on YAP activity through direct phosphorylation. Moreover, aberrant expression of YAP and Aurora A signaling is highly correlated with triple-negative breast cancer (TNBC). We herein provide evidence to establish the functional relevance of this newly discovered regulatory axis in TNBC.
Journal Article
Determination of band alignment in the single-layer MoS2/WSe2 heterojunction
The emergence of two-dimensional electronic materials has stimulated proposals of novel electronic and photonic devices based on the heterostructures of transition metal dichalcogenides. Here we report the determination of band offsets in the heterostructures of transition metal dichalcogenides by using microbeam X-ray photoelectron spectroscopy and scanning tunnelling microscopy/spectroscopy. We determine a type-II alignment between MoS
2
and WSe
2
with a valence band offset value of 0.83 eV and a conduction band offset of 0.76 eV. First-principles calculations show that in this heterostructure with dissimilar chalcogen atoms, the electronic structures of WSe
2
and MoS
2
are well retained in their respective layers due to a weak interlayer coupling. Moreover, a valence band offset of 0.94 eV is obtained from density functional theory, consistent with the experimental determination.
The alignment of the bandgap of adjacent materials in a heterostructure largely determines the electronic properties of a device. Here, the authors measure the conduction and valance band offsets at the interface between two two-dimensional materials: molybdenum disulphide and tungsten diselenide.
Journal Article
Why are there hotspot mutations in the TP53 gene in human cancers?
The p53 gene contains homozygous mutations in ~50–60% of human cancers. About 90% of these mutations encode missense mutant proteins that span ~190 different codons localized in the DNA-binding domain of the gene and protein. These mutations produce a protein with a reduced capacity to bind to a specific DNA sequence that regulates the p53 transcriptional pathway. Eight of these mutations are localized in codons that account for ~28% of the total p53 mutations and these alleles appear to be selected for preferentially in human cancers of many tissue types. This article explores the question 'Why are there hotspot mutations in the p53 gene in human cancers?' Four possible reasons for this are considered; (1) the hotspot mutant alleles produce a protein that has a highly altered structure, (2) environmental mutagens produce allele-specific changes in the p53 gene, (3) these mutations arise at selected sites in the gene due to a specific DNA sequence, such as a methylated cytosine residue in a CpG dinucleotide, which has a higher mutation rate changing C to T nucleotides, (4) along with the observed change in mutant p53 proteins, which produce a loss of function (DNA binding and transcription), some mutant proteins have an allele-specific gain of function that promotes cancer. Evidence is presented that demonstrates the first three possibilities all contribute some property to this list of hotspot mutations. The fourth possibility remains to be tested.
Journal Article
EZH2 contributes to the response to PARP inhibitors through its PARP-mediated poly-ADP ribosylation in breast cancer
Inhibitors against poly (ADP-ribose) polymerase (PARP) are promising targeted agents currently used to treat
BRCA
-mutant ovarian cancer and are in clinical trials for other cancer types, including
BRCA
-mutant breast cancer. To enhance the clinical response to PARP inhibitors (PARPis), understanding the mechanisms underlying PARPi sensitivity is urgently needed. Here, we show enhancer of zeste homolog 2 (EZH2), an enzyme that catalyzes H3 lysine trimethylation and associates with oncogenic function, contributes to PARPi sensitivity in breast cancer cells. Mechanistically, upon oxidative stress or alkylating DNA damage, PARP1 interacts with and attaches poly-ADP-ribose (PAR) chains to EZH2. PARylation of EZH2 by PARP1 then induces PRC2 complex dissociation and EZH2 downregulation, which in turn reduces EZH2-mediated H3 trimethylation. In contrast, inhibition of PARP by PARPi attenuates alkylating DNA damage-induced EZH2 downregulation, thereby promoting EZH2-mediated gene silencing and cancer stem cell property compared with PARPi-untreated cells. Moreover, the addition of an EZH2 inhibitor sensitizes the
BRCA
-mutant breast cells to PARPi. Thus, these results may provide a rationale for combining PARP and EZH2 inhibition as a therapeutic strategy for
BRCA-
mutated breast and ovarian cancers.
Journal Article