430 research outputs found

    Collective Modes and Raman Scattering in One Dimensional Electron Systems

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    In this paper, we review recent development in the theory of resonant inelastic light (Raman) scattering in one-dimensional electron systems. The particular systems we have in mind are electron doped GaAs based semiconductor quantum wire nanostructures, although the theory can be easily modified to apply to other one-dimensional systems. We compare the traditional conduction-band-based non-resonant theories with the full resonant theories including the effects of interband transitions. We find that resonance is essential in explaining the experimental data in which the single particle excitations have finite spectral weights comparable to the collective charge density excitations. Using several different theoretical models (Fermi liquid model, Luttinger liquid model, and Hubbard model) and reasonable approximations, we further demonstrate that the ubiquitously observed strong single particle excitations in the experimental Raman spectra cannot be explained by the spinless multi-spinon excitations in the Luttinger liquid description. The observability of distinct Luttinger liquid features in the Raman scattering spectroscopy is critically discussed.Comment: A review to be published in the special issue of Solid State Communications on one-dimensional system

    Characterization of amoxicillin‐ and clavulanic acid‐specific T cells in patients with amoxicillin‐clavulanate–induced liver injury

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    Drug‐induced liver injury (DILI) frequently has a delayed onset with several human leukocyte antigen (HLA) genotypes affecting susceptibility, indicating a potential role for the adaptive immune system in the disease. The aim of this study was to investigate whether drug‐responsive T lymphocytes are detectable in patients who developed DILI with the combination, antimicrobial amoxicillin‐clavulanate. Lymphocytes from 6 of 7 patients were found to proliferate and/or secrete interferon‐gamma (IFN‐γ) when cultured with amoxicillin and/or clavulanic acid. Amoxicillin (n = 105) and clavulanic acid (n = 16) responsive CD4+ and CD8+ T‐cell clones expressing CCR, chemokine (C‐C motif) receptor 4, CCR9, and chemokine (C‐X‐C motif) receptor 3 were generated from patients with and without HLA risk alleles; no cross‐reactivity was observed between the two drug antigens. Amoxicillin clones were found to secrete a heterogeneous panel of mediators, including IFN‐γ, interleukin‐22 and cytolytic molecules. In contrast, cytokine secretion by the clavulanic acid clones was more restricted. CD4+ and CD8+ clones were major histocompatability complex class II and I restricted, respectively, with the drug antigen being presented to CD4+ clones in the context of HLA‐DR molecules. Several pieces of evidence indicate that the clones were activated by a hapten mechanism: First, professional antigen‐presenting cells (APCs) were required for optimal activation; second, pulsing APCs for 4‐16 hours activated the clones; and third, inhibition of processing abrogated the proliferative response and cytokine release. Conclusion: Both amoxicillin‐ and clavulanic acid–specific T cells participate in the liver injury that develops in certain patients exposed to amoxicillin‐clavulanate. (Hepatology 2015;62:887‐899

    Counterfactuality of "counterfactual" communication

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    The counterfactuality of the recently proposed protocols for direct quantum communication is analyzed. It is argued that the protocols can be counterfactual only for one value of the transmitted bit. The protocols achieve a reduced probability of detection of the particle in the transmission channel by increasing the number of paths in the channel. However, this probability is not lower than the probability of detecting a particle actually passing through such a multi-path channel, which was found to be surprisingly small. The relation between security and counterfactuality of the protocols is discussed. An analysis of counterfactuality of the protocols in the framework of the Bohmian interpretation is performed.Comment: Critical analysis of arXiv:1206.2042 and Phys. Rev. A 89, 052334. Revised according to comments of several referees, accepted for publication in J. Phys.

    QTLs for oil yield components in an elite oil palm (Elaeis guineensis) cross

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    Increased modern farming of superior types of the oil palm, Elaeis guineensis Jacq., which has naturally efficient oil biosynthesis, has made it the world’s foremost edible oil crop. Breeding improvement is, however, circumscribed by time and costs associated with the tree’s long reproductive cycle, large size and 10–15 years of field testing. Marker-assisted breeding has considerable potential for improving this crop. Towards this, quantitative trait loci (QTL) linked to oil yield component traits were mapped in a high-yield population. In total, 164 QTLs associated with 21 oil yield component traits were discovered, with cumulative QTL effects increasing in tandem with the number of QTL markers and matching the QT+ alleles for each trait. The QTLs confirmed all traits to be polygenic, with many genes of individual small effects on independent loci, but epistatic interactions are not ruled out. Furthermore, several QTLs maybe pleiotropic as suggested by QTL clustering of inter-related traits on almost all linkage groups. Certain regions of the chromosomes seem richer in the genes affecting a particular yield component trait and likely encompass pleiotropic, epistatic and heterotic effects. A large proportion of the identified additive effects from QTLs may actually arise from genic interactions between loci. Comparisons with previous mapping studies show that most of the QTLs were for similar traits and shared similar marker intervals on the same linkage groups. Practical applications for such QTLs in marker-assisted breeding will require seeking them out in different genetic backgrounds and environments

    Flexible and Asymmetric Ligand in Constructing Coordinated Complexes: Synthesis, Crystal Structures and Fluorescent Characterization

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    Flexible and asymmetric ligand L [L = 1-((pyridin-3-yl)methyl)-1H-benzotriazole], is used as a basic backbone to construct complicated metal-organic frameworks. Two new polymers, namely, [Ag2(L)2(NO3)2]n (1) and [Ag(L)(ClO4)]n (2), were synthesized and characterized by X-ray structure analysis and fluorescent spectroscopy. The complex 1 gives an “S” type double helical conformation, whereas complex 2 exhibits a 1D zigzag configuration. Different anions affect the silver coordination geometry and crystal packing topology

    Pioglitazone Improves Mitochondrial Function in the Remnant Kidney and Protects against Renal Fibrosis in 5/6 Nephrectomized Rats

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    Pioglitazone is a type of peroxisome proliferator-activated receptor γ (PPARγ) agonist and has been demonstrated to be effective in chronic kidney diseases (CKD) treatment. However, the underlying mechanism involved in the renoprotection of pioglitazone has not been fully revealed. In the present study, the renoprotective mechanism of pioglitazone was investigated in 5/6 nephrectomized (Nx) rats and TGF-β1-exposed HK-2 cells. Pioglitazone attenuated renal injury and improved renal function, as examined by 24 h urinary protein, blood urea nitrogen and plasma creatinine in Nx rats. Renal fibrosis and enhanced expressions of profibrotic proteins TGF-β1, fibronectin and collagen I caused by Nx were significantly alleviated by pioglitazone. In addition, pioglitazone protected mitochondrial functions by stabilizing the mitochondrial membrane potential, inhibiting ROS generation, maintaining ATP production and the activities of complexes I and III, and preventing cytochrome C leakage from mitochondria. Pioglitazone also upregulated the expression levels of ATP synthase β, COX I and NDUFB8, which were downregulated in the kidney of Nx rats and TGF-β1-exposed HK-2 cells. Furthermore, pioglitazone increased fusion proteins Opa-1 and Mfn2 expressions and decreased fission protein Drp1 expression. The results imply that pioglitazone may exert the renoprotective effects through modulating mitochondrial electron transport chain and mitochondrial dynamics in CKD. Finally, these recoveries were completely or partly inhibited by GW9662, which suggests that these effects at least partly PPARγ dependent. This study provides evidence for the pharmacological mechanism of pioglitazone in the treatment of CKD

    A comparison of perceived uselessness between centenarians and non-centenarians in China

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    Abstract Background Self-perceived uselessness is associated with poorer health in older adults. However, it is unclear whether there is a difference in self-perceived uselessness between centenarians and non-centenarians, and if so, which factors contributed to the difference. Methods We used four waves of a nationwide longitudinal dataset from 2005 to 2014 in China to investigate these research goals. We first performed multinomial logit regression models to examine the risk of the high or moderate frequency of self-perceived uselessness relative to the low frequency among centenarians (5778 persons) in comparison with non-centenarians aged 65–99 (20,846 persons). We then conducted a cohort analysis for those born in 1906–1913, examining differences in self-perceived uselessness between those centenarians and those died between ages 91 and 99 during 2005–2014. Results Compared to persons aged 65–79, centenarians had 84% (relative risk ratio (RRR) = 1.84, 95% CI:1.69–2.01) and 35% (RRR = 1.35, 95% CI: 1.25–1.46) higher risk to have the high frequency and the moderate frequency of feeling useless versus low frequency, respectively, when only demographic factors were controlled for. However, centenarians had 31% (RRR = 0.69, 95% CI: 0.54–0.88), 43% (RRR = 0.57, 95% CI: 0.49–0.68), and 25% (RRR = 0.75, 95% CI: 0.67–0.83) lower risk, respectively, to have the high frequency of self-perceived uselessness relative to the low frequency when a wide set of study covariates were controlled for. In the case of the moderate versus the low frequency of self-perceived uselessness, the corresponding figures were 18% (RRR = 0.82, 95% CI: 0.66–1.02), 22% (RRR = 0.78, 95%CI: 0.67–0.90), and 13% (RRR = 0.87, 95% CI: 0.79–0.96), respectively. The cohort analysis further indicates that those who became centenarians were 36–39% less likely than those died at ages 91–94 to report the high and the moderate frequencies of self-perceived uselessness versus the low frequency; no difference was found between centenarians and those died at ages 95–99. In both period and cohort analyses, behavioral and health-related factors affected the perception substantially. Conclusions Overall, centenarians were less likely to perceive themselves as useless compared to non-centenarians of younger birth cohorts when a wide set of covariates were considered and non-centenarians of the same birth cohort. How centenarians manage to do so remains an open question. Our findings may help improve our understanding about the longevity secrets of centenarians

    IDO-1 Promotes Pulmonary Vascular Remodeling Via Kynurenine Pathway in Pulmonary Arterial Hypertension

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    BACKGROUND: Activation of the plasma kynurenine pathway (KP) may contribute to the progression of pulmonary arterial hypertension (PAH). We investigated the functional role and molecular mechanisms of KP activation in PAH. METHODS: KP activity was measured in the lungs and plasma of humans and rodents with pulmonary hypertension (PH). KP activity was modulated in lung microvascular endothelial cells in vitro, and through daily oral administration of epacadostat, an inhibitor of IDO-1 (indoleamine 2,3-dioxygenase), the rate-limiting enzyme of the KP, in rats with monocrotaline-induced PH. RESULTS: IDO-1 expression was increased in peripheral blood mononuclear cells but not in lung tissue of patients with PAH and in rats with monocrotaline-induced PH. Epacadostat prevented KP activation and the development of monocrotaline-induced PH, significantly reduced right ventricular systolic pressure (58±9 versus 42±4 and 46±6 mm Hg for placebo versus epacadostat 50 and 100 mg/kg, respectively, P&lt;0.001), pulmonary arterial remodeling (wall thickness, 64±3 versus 58±3 and 58±3%, P&lt;0.001), perivascular inflammation, and right ventricular remodeling (Fulton index, 0.49±0.05 versus 0.36±0.06 and 0.39±0.04, P&lt;0.001). IDO-1 overexpression contributed to KP activation and de novo nicotinamide adenine dinucleotide+ synthesis, increased mitochondrial membrane potential, and endothelial cell proliferation. Inhibition of IDO-1 using siRNA or epacadostat reversed these effects and inhibited the inflammatory response. CONCLUSIONS: Increased IDO-1 expression in peripheral blood mononuclear cells may drive KP activation and promote pulmonary vascular remodeling in PAH. Epacadostat prevents the development of monocrotaline-induced PH. These findings suggest a novel approach for the treatment of PAH.</p
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