3,080 research outputs found

    Extraction of higher-order nonlinear electronic response to strong field excitation in solids using high harmonic generation

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    State-of-the-art experiments employ strong ultrafast optical fields to study the nonlinear response of electrons in solids on an attosecond time-scale. Notably, a recent experiment retrieved a 3rd order nonlinear susceptibility by comparing the nonlinear response induced by a strong laser field to a linear response induced by the otherwise identical weak field. In parallel, experiments have demonstrated high harmonic generation (HHG) in solids, a highly nonlinear process that until recently had only been observed in gases. The highly nonlinear nature of HHG has the potential to extract even higher order nonlinear susceptibility terms, and thereby characterize the entire response of the electronic system to strong field excitation. However, up till now, such characterization has been elusive due to a lack of direct correspondence between high harmonics and nonlinear susceptibilities. Here, we demonstrate a regime where such correspondence can be clearly made, extracting nonlinear susceptibilities (7th, 9th, and 11th) from sapphire of the same order as the measured high harmonics. The extracted high order susceptibilities show angular-resolved periodicities arising from variation in the band structure with crystal orientation. Nonlinear susceptibilities are key to ultrafast lightwave driven optoelectronics, allowing petahertz scaling manipulation of the signal. Our results open a door to multi-channel signal processing, controlled by laser polarization

    Allergic Responses Induced by a Fungal Biopesticide Metarhizium anisopliae and House Dust Mite Are Compared in a Mouse Model

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    Biopesticides can be effective in controlling their target pest. However, research regarding allergenicity and asthma development is limited. We compared the ability of fungal biopesticide Metarhizium anisopliae (MACA) and house dust mite (HDM) extracts to induce allergic responses in BALB/c mice. The extracts were administered by intratracheal aspiration at doubling doses (2.5–80 μg protein) 4X over a four-week period. Three days after the last exposure, serum and bronchoalveolar lavage fluid (BALF) were collected. The extracts' relative allergenicity was evaluated based on response robustness (lowest significant dose response compared to control (0 μg)). MACA induced a more robust serum total IgE response than HDM. However, in the antigen-specific IgE assay, a similar dose of both MACA and HDM was required to achieve the same response level. Our data suggest a threshold dose of MACA for allergy induction and that M. anisopliae may be similar to HDM in allergy induction potential

    Design and Investigation of RGB-type LED Visible Light Communication System

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    This paper examines the feasibility of a Red Green Blue (RGB)-type Light Emitting Diode (LED) Visible Light Communication (VLC) system based on wavelength division multiplexing (WDM). Each color in the RGB-LED is individually modulated to increase the data rate by three times as compared to the single channel modulation approach used in conventional VLC system. Color filters are employed to detect separately the RGB signals at the receiver side. The proposed system utilized a reflector to improve the performance and the system is lens-free. In this work, an approach of approximated WDM testing is adopted due to the incapability of multiplexing by the microcontroller at higher data rate. The proposed system is demonstrated to transmit and receive data at a maximum distance of 1.4m, with total data transmission speed of 345.6 kbps using standard WDM, while a total speed of 1.5 Mbps up to maximum distance of 1.2m and 3 Mbps up to maximum distance of 0.7m is achieved by the approach of approximated WDM testing

    There are laterality effects in memory functioning in children/adolescents with focal epilepsy.

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    In a sample of individuals with childhood focal epilepsy, children/adolescents with left hemisphere foci outperformed those with right foci on both measures of nonverbal learning. Participants with left foci performed worse than controls on paired associate delayed recall and semantic memory, and they had greater laterality effects in IQ. Participants with right foci performed worse than controls on delayed facial recognition. Both groups displayed reduced focused attention and poor passage retention over time. Although participants with bilateral foci displayed poor learning and lower IQ than controls, they did not have worse impairment than those with a unilateral focus

    Cholestenoic acid, an endogenous cholesterol metabolite, is a potent γ-secretase modulator.

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    BackgroundAmyloid-β (Aβ) 42 has been implicated as the initiating molecule in the pathogenesis of Alzheimer's disease (AD); thus, therapeutic strategies that target Aβ42 are of great interest. γ-Secretase modulators (GSMs) are small molecules that selectively decrease Aβ42. We have previously reported that many acidic steroids are GSMs with potencies ranging in the low to mid micromolar concentration with 5β-cholanic acid being the most potent steroid identified GSM with half maximal effective concentration (EC50) of 5.7 μM.ResultsWe find that the endogenous cholesterol metabolite, 3β-hydroxy-5-cholestenoic acid (CA), is a steroid GSM with enhanced potency (EC50 of 250 nM) relative to 5β-cholanic acid. CA i) is found in human plasma at ~100-300 nM concentrations ii) has the typical acidic GSM signature of decreasing Aβ42 and increasing Aβ38 levels iii) is active in in vitro γ-secretase assay iv) is made in the brain. To test if CA acts as an endogenous GSM, we used Cyp27a1 knockout (Cyp27a1-/-) and Cyp7b1 knockout (Cyp7b1-/-) mice to investigate if manipulation of cholesterol metabolism pathways relevant to CA formation would affect brain Aβ42 levels. Our data show that Cyp27a1-/- had increased brain Aβ42, whereas Cyp7b1-/- mice had decreased brain Aβ42 levels; however, peripheral dosing of up to 100 mg/kg CA did not affect brain Aβ levels. Structure-activity relationship (SAR) studies with multiple known and novel CA analogs studies failed to reveal CA analogs with increased potency.ConclusionThese data suggest that CA may act as an endogenous GSM within the brain. Although it is conceptually attractive to try and increase the levels of CA in the brain for prevention of AD, our data suggest that this will not be easily accomplished

    Large-Scale Numerical Modeling of Melt and Solution Crystal Growth

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    We present an overview of mathematical models and their large-scale numerical solution for simulating different phenomena and scales in melt and solution crystal growth. Samples of both classical analyses and state-of-the-art computations are presented. It is argued that the fundamental multi-scale nature of crystal growth precludes any one approach for modeling, rather successful crystal growth modeling relies on an artful blend of rigor and practicality

    Genomic analysis of the chromosome 15q11-q13 Prader-Willi syndrome region and characterization of transcripts for GOLGA8E and WHCD1L1 from the proximal breakpoint region

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    <p>Abstract</p> <p>Background</p> <p>Prader-Willi syndrome (PWS) is a neurobehavioral disorder characterized by neonatal hypotonia, childhood obesity, dysmorphic features, hypogonadism, mental retardation, and behavioral problems. Although PWS is most often caused by a paternal interstitial deletion of a 6-Mb region of chromosome 15q11-q13, the identity of the exact protein coding or noncoding RNAs whose deficiency produces the PWS phenotype is uncertain. There are also reports describing a PWS-like phenotype in a subset of patients with full mutations in the <it>FMR1 </it>(fragile X mental retardation 1) gene. Taking advantage of the human genome sequence, we have performed extensive sequence analysis and molecular studies for the PWS candidate region.</p> <p>Results</p> <p>We have characterized transcripts for the first time for two UCSC Genome Browser predicted protein-coding genes, <it>GOLGA8E </it>(golgin subfamily a, 8E) and <it>WHDC1L1 </it>(WAS protein homology region containing 1-like 1) and have further characterized two previously reported genes, <it>CYF1P1 </it>and <it>NIPA2</it>; all four genes are in the region close to the proximal/centromeric deletion breakpoint (BP1). <it>GOLGA8E</it> belongs to the golgin subfamily of coiled-coil proteins associated with the Golgi apparatus. Six out of 16 golgin subfamily proteins in the human genome have been mapped in the chromosome 15q11-q13 and 15q24-q26 regions. We have also identified more than 38 copies of <it>GOLGA8E</it>-like sequence in the 15q11-q14 and 15q23-q26 regions which supports the presence of a <it>GOLGA8E</it>-associated low copy repeat (LCR). Analysis of the 15q11-q13 region by PFGE also revealed a polymorphic region between BP1 and BP2. <it>WHDC1L1 </it>is a novel gene with similarity to mouse <it>Whdc1 </it>(WAS protein homology region 2 domain containing 1) and human JMY protein (junction-mediating and regulatory protein). Expression analysis of cultured human cells and brain tissues from PWS patients indicates that <it>CYFIP1 </it>and <it>NIPA2</it> are biallelically expressed. However, we were not able to determine the allele-specific expression pattern for <it>GOLGA8E </it>and <it>WHDC1L1 </it>because these two genes have highly related sequences that might also be expressed.</p> <p>Conclusion</p> <p>We have presented an updated version of a sequence-based physical map for a complex chromosomal region, and we raise the possibility of polymorphism in the genomic orientation of the BP1 to BP2 region. The identification of two new proteins <it>GOLGA8E</it> and <it>WHDC1L1</it> encoded by genes in the 15q11-q13 region may extend our understanding of the molecular basis of PWS. In terms of copy number variation and gene organization, this is one of the most polymorphic regions of the human genome, and perhaps the single most polymorphic region of this type.</p
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