187 research outputs found
Full counting statistics of renormalized dynamics in open quantum transport system
The internal dynamics of a double quantum dot system is renormalized due to
coupling respectively with transport electrodes and a dissipative heat bath.
Their essential differences are identified unambiguously in the context of full
counting statistics. The electrode coupling caused level detuning
renormalization gives rise to a fast-to-slow transport mechanism, which is not
resolved at all in the average current, but revealed uniquely by pronounced
super-Poissonian shot noise and skewness. The heat bath coupling introduces an
interdot coupling renormalization, which results in asymmetric Fano factor and
an intriguing change of line shape in the skewness.Comment: 9 pages, 5 figure
Electron transfer theory revisit: Quantum solvation effect
The effect of solvation on the electron transfer (ET) rate processes is
investigated on the basis of the exact theory constructed in J. Phys. Chem. B
Vol. 110, (2006); quant-ph/0604071. The nature of solvation is studied in a
close relation with the mechanism of ET processes. The resulting Kramers'
turnover and Marcus' inversion characteristics are analyzed accordingly. The
classical picture of solvation is found to be invalid when the solvent
longitudinal relaxation time is short compared with the inverse temperature.Comment: 5 pages, 3 figures. J. Theo. & Comput. Chem., accepte
Copy number variants in pharmacogenetic genes
Variation in drug efficacy and toxicity remains an important clinical concern. Presently, single nucleotide polymorphisms (SNP) only explain a portion of this problem, even in situations where the pharmacological trait is clearly heritable. The Human CNV Project identified copy number variations (CNVs) across approximately 12% of the human genome, and these CNVs were considered causes of diseases. Although the contribution of CNVs to the pathogenesis of many common diseases is questionable, CNVs play a clear role in drug related genes by altering drug metabolizing and drug response. Here we provide a comprehensive review of the clinical relevance of CNVs to drug efficacy, toxicity, disease prevalence in world populations and discuss the implication of using CNVs as diagnosis in clinical intervention
Geometry-independent antenna based on Epsilon-near-zero medium
It is well known that electromagnetic radiation from radiating elements (e.g., antennas,
apertures, etc.) shows dependence on the elementâs geometry shape in terms of operating
frequencies. This basic principle is ubiquitous in the design of radiators in multiple applications
spanning from microwave, to optics and plasmonics. The emergence of epsilon-near-zero
media exceptionally allows for an infinite wavelength of electromagnetic waves, manifesting
exotic spatially-static wave dynamics which is not dependent on geometry. In this work, we
analyze theoretically and verify experimentally such geometry-independent features for
radiation, thus presenting a novel class of radiating resonators, i.e., antennas, with an operating frequency irrelevant to the geometry shape while only determined by the host materialâs
dispersions. Despite being translated into different shapes and topologies, the designed
epsilon-near-zero antenna resonates at a same frequency, while exhibiting very different
far-field radiation patterns, with beams varying from wide to narrow, or even from single to
multiple. Additionally, the photonic doping technique is employed to facilitate the
high-efficiency radiation. The material-determined geometry-independent radiation may lead
to numerous applications in flexible design and manufacturing for wireless communications,
sensing, and wavefront engineering. © 2022, The Author(s).Y.L. acknowledges partial support from National Natural Science Foundation of China (NSFC) under grant 62022045, and in part by supported by Tsinghua University Initiative Scientific Research Program. I.L. acknowledges support from Ramón y Cajal fellowship RYC2018-024123-I, project RTI2018-093714-301J-I00 sponsored by MCIU/AEI/FEDER/UE, and ERC Starting Grant 948504
Dispersion coding of ENZ media via multiple photonic dopants
Epsilon-near-zero (ENZ) media are opening up exciting opportunities to observe exotic wave phenomena. In this work, we demonstrate that the ENZ medium comprising multiple dielectric photonic dopants would yield a comb-like dispersion of the effective permeability, with each magnetic resonance dominated by one specific dopant. Furthermore, at multiple frequencies of interest, the resonant supercouplings appearing or not can be controlled discretely via whether corresponding dopants are assigned or not. Importantly, the multiple dopants in the ENZ host at their magnetic resonances are demonstrated to be independent. Based on this platform, the concept of dispersion coding is proposed, where photonic dopants serve as âbitsâ to program the spectral response of the whole composite medium. As a proof of concept, a compact multi-doped ENZ cavity is fabricated and experimentally characterized, whose transmission spectrum is manifested as a multi-bit reconfigurable frequency comb. The dispersion coding is demonstrated to fuel a batch of innovative applications including dynamically tunable comb-like dispersion profiled filters, radio-frequency identification tags, etc.© 2022, The Author(s).Y.L. acknowledges partial support from the National Natural Science Foundation of China (NSFC) under grant 62022045, and in part by the Beijing Nova Program of Science and Technology under Grant Z191100001119082, as well as the support from the Beijing National Research Center for Information Science and Technology. I.L. acknowledges support from project RTI2018-093714-J-I00 sponsored by MCIU/AEI/FEDER/UE
Unresolved excess accumulation of myelin-derived cholesterol contributes to scar formation after spinal cord injury
Background: Spinal cord injury triggers complex pathological cascades,
resulting in destructive tissue damage and incomplete tissue repair. Scar
formation is generally considered as a barrier for regeneration in central
nervous system (CNS), while the intrinsic mechanism of scar-forming after
spinal cord injury has not been completed deciphered. Methods: We assessed
cholesterol hemostasis in spinal cord lesions and injured peripheral nerves
using confocal reflection microscopy and real-time PCR analyses. The
involvement of the proteins, which were predicted to promote cholesterol efflux
in spinal cord lesions, were assessed with Liver X receptor (LXR) agonist and
Apolipoprotein E (APOE) deficiency. The role of reverse cholesterol transport
(RCT) in cholesterol clearance was examined in APOE KO mice injured sciatic
nerves and myelin-overloaded macrophages in vitro. Finally, we determined the
consequence of excess cholesterol accumulation in CNS by transplantation of
myelin into neonatal spinal cord lesions. Results: We found that excess
cholesterol accumulates in phagocytes and is inefficiently removed in spinal
cord lesions in young-adult mice. Interestingly, we observed that excessive
cholesterol also accumulates in injured peripheral nerves, but is subsequently
removed by RCT. Meanwhile, preventing RCT led to macrophage accumulation and
fibrosis in injured peripheral nerves. Furthermore, the neonatal mouse spinal
cord lesions are devoid of myelin-derived lipids, and able to heal without
excess cholesterol accumulation. We found that transplantation of myelin into
neonatal lesions disrupts healing with excessive cholesterol accumulation,
persistent macrophage activation and fibrosis, indicating myelin-derived
cholesterol plays a critical role in impaired wound healing
Real-time counting of single electron tunneling through a T-shaped double quantum dot system
Real-time detection of single electron tunneling through a T-shaped double
quantum dot is simulated, based on a Monte Carlo scheme. The double dot is
embedded in a dissipative environment and the presence of electrons on the
double dot is detected with a nearby quantum point contact. We demonstrate
directly the bunching behavior in electron transport, which leads eventually to
a super-Poissonian noise. Particularly, in the context of full counting
statistics, we investigate the essential difference between the dephasing
mechanisms induced by the quantum point contact detection and the coupling to
the external phonon bath. A number of intriguing noise features associated with
various transport mechanisms are revealed.Comment: 8 pages, 5 figure
Genetic Variants of Pregnane X Receptor (PXR) and CYP2B6 Affect the Induction of Bupropion Hydroxylation by Sodium Ferulate
This study investigated the effects of pregnane X receptor (PXR/NR1I2) and CYP2B6 genetic variants on sodium ferulate (SF)-mediated induction of bupropion hydroxylation. The pharmacokinetics of bupropion and hydroxybupropion were evaluated after an oral dose of bupropion (150 mg) administered with and without SF pretreatment for 14 days in 33 healthy subjects. The area under the time-concentration curve (AUC) ratio of AUC_hyd (AUC(0-â) of hydroxybupropion)/AUC_bup (AUC(0-â) of bupropion) represents the CYP2B6 hydroxylation activity, which was significantly lower in CYP2B6*6 carriers (NR1I2 TGT noncarriers or carriers) than in noncarriers in both the basal and SF-induced states (p-value<0.05). AUC ratio and AUC_hyd of NR1I2 -24113AA variant were markedly lower than GA and GG genotypes (7.5±2.1 versus 14.5±3.3 and 20.6±1.1, and 8873±1431 versus 14,504±2218 and 17,586±1046) in the induced states. However, -24020(-)/(-) variant didn't show significant difference in the induction of CYP2B6 hydroxylation activity by SF compared with other -24020[GAGAAG]/(-) genotypes. NR1I2 TGT haplotype (-25385T+g.7635G+g.8055T) carriers exhibited a significantly decreased AUC ratio, compared with TGT noncarriers, in the basal states (7.6±1.0 versus 9.7±1.0), while this result wasn't observed in CYP2B6*6 noncarriers. Moreover, individuals with complete mutation-type [CYP2B6*6/*6+NR1I2 TGT+ -24113AA+ -24020 (-)/(-)] showed even lower percent difference of AUC ratio (8.7±1.2 versus 39.5±8.2) than those with complete wild-type. In conclusion, it is suggested that NR1I2 variants decrease the bupropion hydroxylation induced by SF treatment, particularly in CYP2B6*6 carriers
EPRENNID: An evolutionary prototype reduction based ensemble for nearest neighbor classification of imbalanced data
Classification problems with an imbalanced class distribution have received an increased amount of attention within the machine learning community over the last decade. They are encountered in a growing number of real-world situations and pose a challenge to standard machine learning techniques. We propose a new hybrid method specifically tailored to handle class imbalance, called EPRENNID. It performs an evolutionary prototype reduction focused on providing diverse solutions to prevent the method from overfitting the training set. It also allows us to explicitly reduce the underrepresented class, which the most common preprocessing solutions handling class imbalance usually protect. As part of the experimental study, we show that the proposed prototype reduction method outperforms state-of-the-art preprocessing techniques. The preprocessing step yields multiple prototype sets that are later used in an ensemble, performing a weighted voting scheme with the nearest neighbor classifier. EPRENNID is experimentally shown to significantly outperform previous proposals
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