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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Octave-Spanning High-Repetition-Rate Mid-IR Supercontinuum for Frequency Comb Synthesis
摘要： Ventricular enlargement (VE) is commonly observed in aging and fragile X-associated tremor/ataxia syndrome (FXTAS), a late-onset neurodegenerative disorder. VE may generate a mechanical force causing structural deformation. In this longitudinal study, we examined the relationships between VE and structural changes in the corpus callosum (CC) and putamen. MRI scans (2-7/person over 0.2-7.5 years) were acquired from 22 healthy controls, 26 unaffected premutation carriers (PFX-), and 39 carriers affected with FXTAS (PFX+). Compared with controls, PFX- demonstrated enlarged fourth ventricles whereas PFX+ displayed enlargement in both third and fourth ventricles, CC thinning, putamen atrophy/deformation (thinning and increased distance), and accelerated expansions in lateral ventricles. Common for all groups, baseline VE predicted accelerated CC thinning and putamen atrophy/deformation and conversely, baseline CC and putamen atrophy/deformation and enlarged third and fourth ventricles predicted accelerated lateral ventricular expansion. The results suggest a progressive VE within the four ventricles as FXTAS develops and a deleterious cycle between VE and brain deformation that may commonly occur during aging and FXTAS progression but become accelerated in FXTAS.
关键词： FXTAS,MRI,neurodegenerative disorder,fragile X premutation,FMR1,normal pressure hydrocephalus
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Generalized Conductance Fluctuations in Anderson Localization at the two Limits of Disorder
摘要： Anderson localization (AL) of light, one of the most exotic mesoscopic phenomena, can be realized at two limits of disorder, namely, near-periodic disorder or strong disorder. AL can be characterized by sub-unity conductance. A critical parameter of interest is the fluctuations of conductance which reveals the statistical behaviour of the system and offers a more complete description of the underlying physics. However, the conventional technique of quantifying conductance precludes the measurement of the fluctuations thereof. In this work, we achieve Anderson localization of light in Gallium Arsenide membranes at both near-periodic disorder and strong disorder. We measure the generalized conductance fluctuations using the intensity distribution of light, and reveal hitherto unknown features of transport under the two approaches of localization. Figure 1 (a) and (b) depict the SEM images of ordered and strongly disordered structures. Fig. 1(c) shows the photonic mode formed due to the counter-propagating Bloch modes in the periodic system, and (d) shows the Anderson localized mode formed under strong disorder. Similar mode was also obtained at near-periodic disorder (not shown). The variance of the intensity distribution was used to compute the generalized conductance (cid:1859)′ = 4/3((cid:1874)(cid:1853)(cid:1870)((cid:1871)(cid:3028)(cid:3029)) ? 1), where (cid:1871)(cid:3028)(cid:3029) is the total transmission normalized to the ensemble average. The generalized conductance can be calculated for each configuration, so it facilitates a statistically consistent quantification. Fig. 1(e) shows the experimentally measured distribution of ln ((cid:1859)(cid:4593)) in the passband (black line) and in the stopband (red line). At weak/moderate disorder, the distributions are asymmetric, with long-tails at large ln((cid:1859)(cid:4593)). The passband modes are delocalized (ln((cid:1859)(cid:4593)) > 0), while the stopband modes show localization (ln((cid:1859)(cid:4593)) < 0). At strong disorder, the band-dependence is lost, and the ln((cid:1859)(cid:4593)) is seen to follow a normal distribution as expected. Clearly, at strong disorder, the entire distribution lies below zero, indicating localization of all modes, unlike in the weak/moderate disorder in the stopband, where a substantial number of modes are delocalized. This important difference in the localization physics is revealed by the statistical analysis of (cid:1859)(cid:4593).
关键词： Gallium Arsenide membranes,disorder,intensity distribution,conductance fluctuations,Anderson localization
更新于2025-09-11 14:15:04
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Energetic Disorder and Activation Energy in Efficient Ternary Organic Solar Cells with Nonfullerene Acceptor Eh‐IDTBR as the Third Component
摘要： Solution processed ternary organic solar cells (OSCs) contain a third component in the active layer besides the donor/acceptor materials. Two main avenues are considered to fabricate ternary OSCs: (i) to improve the short circuit current density by the selected third component that can broaden and/or enhance the absorption of the host films; (ii) to increase the fill factor by adding materials with diverse crystallinity to tune the film morphology. However, little work has been reported for the improvement of open circuit voltage (VOC), energetic disorder, charge transfer state energy (ECT), and activation energy in ternary OSCs. Herein, we used ternary OSCs with active layer composed of PCE10: F8IC: Eh-IDTBR as model to examine these parameters besides the morphology. We found in the ternary device that the additional Eh-IDTBR improved the crystallinity of the acceptor phase in the ternary mixture; the VOC was 58 mV higher than that of the reference caused by the reduced energetic disorder; due to the good miscibility of Eh-IDTBR with both PCE10 and F8IC, only 50 meV in ECT was observed; zero field activation energy was lower than that for the reference. Our findings provide an alternative way to understand the complex ternary structural-electrical properties correlations.
关键词： ternary organic solar cells,charge transfer state energy,crystallinity phase,energetic disorder,activation energy
更新于2025-09-11 14:15:04
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Fast and Simultaneous Determination of Soil Properties Using Laser-Induced Breakdown Spectroscopy (LIBS): A Case Study of Typical Farmland Soils in China
摘要： This work provides a new paradigm for designing a laser crystal requiring a broad luminescent spectrum through spontaneous polarization and local structural disorder. The grown complex ferroelectric crystals Nd-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (Nd:PMNT) have a broad emission spectrum with a full width at half-maximum value of 30 nm, much larger than typical Nd laser crystals (Nd:YAG ≈ 0.8 nm). The internal mechanism of spectral broadening in complex ferroelectric crystals was analyzed using the con?guration coordinate. The shift of the peak site in the 4F3/2 → 4I11/2 transition with temperature was a?ected by structural changes, consistent with the change in dielectric and ferroelectric properties. The family of complex ferroelectric crystals could be an abundant treasure for Nd femtosecond laser crystals requiring a broad luminescent spectrum.
关键词： local disorder,spontaneous polarization,ferroelectric crystals,Pb(Mg1/3Nb2/3)O3,Nd-doped,broad bandwidth emission
更新于2025-09-11 14:15:04
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Hypoactivation of the Right Prefrontal Cortex Underlying Motor-Related Inhibitory Deficits in Children with Autism Spectrum Disorder: A Functional Near-Infrared Spectroscopy Study
摘要： Autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD) are believed to share the symptom of neurocognitive dysfunction in executive functions. Regarding the components of executive functions, however, dysfunction of motor-response inhibitory control in children with ASD remains unclear. Thus, using functional near-infrared spectroscopy (fNIRS), we investigated whether putative inhibitory brain dysfunctions are applicable to children with ASD by adopting a go/no-go task, which has robustly evoked activation in typically developing (TD) children but not in ADHD children. Twenty-four ASD and 24 TD children underwent a go/no-go task, and their cortical hemodynamics were assessed using fNIRS. Relative to TD participants, ASD participants showed reduced activation in the right inferior frontal gyrus and middle frontal gyrus (IFG/MFG) during go/no-go tasks. The current finding suggests that hypoactivation in the right IFG/MFG during a go/no-go task would serve as a potential biomarker for identifying children with ASD.
关键词： autism spectrum disorder,attention-deficit hyperactivity disorder,optical topography,prefrontal cortex,executive dysfunction
更新于2025-09-10 09:29:36
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Feasibility of NIRS-based neurofeedback training in social anxiety disorder: behavioral and neural correlates
摘要： Attention biases towards threat signals have been linked to the etiology and symptomatology of social anxiety disorder (SAD). Dysfunction of the dorsolateral prefrontal cortex (dlPFC) may contribute to attention biases in anxious individuals. The aim of this study was to investigate the feasibility of near-infrared spectroscopy (NIRS) neurofeedback (NF) training—targeting the dlPFC—and its effects on threat-related attention biases of individuals with SAD. 12 individuals with SAD participated in the NIRS-NF training lasting 6–8 weeks and including a total of 15 sessions. NF performance increased significantly, while the attention bias towards threat-related stimuli and SAD symptom severity decreased after the training. The individual increase in neurofeedback performance as well as the individual decrease in SAD symptom severity was correlated with decreased responses to social threat signals in the cerebral attention system. Thus, this pilot study does not only demonstrate that NIRS-based NF is feasible in SAD patients, but also may be a promising method to investigate the causal role of the dlPFC in attention biases in SAD. Its effectiveness as a treatment tool might be examined in future studies.
关键词： Social anxiety disorder,Near-infrared spectroscopy,DlPFC,Laughter,Attention bias
更新于2025-09-10 09:29:36
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Fano Resonances in Flat Band Networks
摘要： Linear wave equations on Hamiltonian lattices with translational invariance are characterized by an eigenvalue band structure in reciprocal space. Flat band lattices have at least one of the bands completely dispersionless. Such bands are coined ?at bands. Flat bands occur in ?ne-tuned networks, and can be protected by (e.g. chiral) symmetries. Recently a number of such systems were realized in structured optical systems, exciton-polariton condensates, and ultracold atomic gases. Flat band networks support compact localized modes. Local defects couple these compact modes to dispersive states and generate Fano resonances in the wave propagation. Disorder (i.e. a ?nite density of defects) leads to a dense set of Fano defects, and to novel scaling laws in the localization length of disordered dispersive states. Nonlinearities can preserve the compactness of ?at band modes, along with renormalizing (tuning) their frequencies. These strictly compact nonlinear excitations induce tunable Fano resonances in the wave propagation of a nonlinear ?at band lattice.
关键词： disorder,nonlinearities,flat band networks,Fano resonances,compact localized modes
更新于2025-09-10 09:29:36
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Intrinsic brain abnormalities in drug-naive patients with obsessive-compulsive disorder: a resting-state functional MRI study
摘要： Background: Using the resting-state functional magnetic resonance imaging (rs-fMRI) in a relatively large sample of drug-naive patients with obsessive-compulsive disorder (OCD), the current study aims to explore alterations in regional and network-level neural function and to determine the association between these alterations in intrinsic neural activity and symptom severity in OCD. Methods: A total of 68 drug-naive OCD patients and 68 healthy control subjects (HCS) were examined using rs-fMRI. Regional cerebral function was evaluated by measuring the fraction of amplitude of low-frequency fluctuation (fALFF). Regions with fALFF alterations were used as seeds in whole-brain functional connectivity (FC) analysis. Statistical analyses of fALFF and FC differences between OCD patients with HCS were performed voxel-by-voxel using a two-sample t-test in Statistical Parametric Mapping version 8 (SPM8). Whole brain correlation analyses were performed to identify the association between functional neural correlates and OCD symptom severity evaluated using Yale-Brown Obsessive Compulsive scale (Y-BOCS) and subscale scores. Results: Relative to HCS, OCD patients showed higher fALFF in the right putamen and right superior frontal gyrus (P < 0.05, corrected for AlphaSim); higher FC in the limbic-striatal circuit and lower FC in the fronto-temporal and fronto-striato-thalamic networks (P < 0.05, corrected for AlphaSim). FC in striato-thalamic junction was negatively correlated with the Y-BOCS total score (r = -0.493, P < 0.001). Conclusion: These findings of focal spontaneous hyperfunction confirmed the prevailing frontal-striatal model of OCD, and altered brain connectivity in large-scale resting-state networks indicated a connectivity-based pathophysiological process in OCD.
关键词： Obsessive-compulsive disorder,Functional connectivity,Resting-state fMRI,Drug-naive,Fractional amplitude of low-frequency fluctuation
更新于2025-09-10 09:29:36
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Coupling to Charge Transfer States Is the Key to Modulate the Optical Bands for Efficient Light-Harvesting in Purple Bacteria.
摘要： The photosynthetic apparatus of purple bacteria uses exciton delocalization and static disorder to modulate the position and broadening of its absorption bands, leading to efficient light harvesting. Its main antenna complex, LH2, contains two rings of identical bacteriochlorophyll pigments, B800 and B850, absorbing at 800 nm and at 850 nm, respectively. It has been an unsolved problem why static disorder of the strongly coupled B850 ring is several times larger than that of the B800 ring. Here we show that mixing between excitons and charge transfer states in the B850 ring is responsible for the effect. The linear absorption spectrum of the LH2 system is simulated by using a multi-scale approach with an exciton Hamiltonian generalized to include the charge transfer states that involve adjacent pigment pairs, with static disorder modelled microscopically by molecular dynamics simulations. Our results show that a sufficient inhomogeneous broadening of the B850 band, needed for efficient light-harvesting, is only obtained by utilizing static disorder in the coupling between local excited and inter-pigment charge transfer states.
关键词： exciton delocalization,B850,B800,charge transfer states,purple bacteria,LH2,molecular dynamics simulations,static disorder,bacteriochlorophyll pigments,photosynthetic apparatus,light harvesting
更新于2025-09-10 09:29:36
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Disorder Engineering in Monolayer Nanosheets Enabling Photothermic Catalysis for Full Solar Spectrum (250 <b>-</b> 2500?nm) Harvesting
摘要： A persistent challenge in classical photocatalyst systems with extended light absorption is the unavoidable trade-off between maximizing light harvesting and sustaining high photoredox capability. Alternatively, cooperative energy conversion through photothermic activation and photocatalytic redox is a promising yet unmet scientific proposition that critically demands a spectrum-tailored catalyst system. Here, we construct a solar thermal-promoted photocatalyst, an ultrathin “biphasic” ordered–disordered D-HNb3O8 junction, which performs two disparate spectral selective functions of photoexcitation by ordered structure and thermal activated conversion via disordered lattice for combinatorial photothermal mediated catalysis. This in situ synthetically immobilized lattice distortion, constrained to a single-entity monolayer structure not only circumvents interfacial incompatibility but also triggers near-field temperature rise at the catalyst–reactant complexes’ proximity to promote photoreaction. Ultimately, a generic full solar conversion improvement for H2 fuel production, organic transformation and water purification is realized.
关键词： redox reaction,photothermic catalysis,defect engineering,order–disorder,full solar spectrum
更新于2025-09-10 09:29:36