71 research outputs found

    Experimental Investigation of Demographic Factors Related to Phishing Susceptibility

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    This paper reports on a simulated phishing experiment targeting 6,938 faculty and staff at George Mason University. The study examined various possible predictors of phishing susceptibility. The focus of the present paper is on demographic factors (including age, gender and position/employment). Since previous studies of age and gender have yielded discrepant results, one purpose of the study was to disambiguate these findings. A second purpose was to compare different types of email phishing exploits. A third objective was to compare the effect of different types of feedback given to those who clicked on one or more of three simulated phishing exploits that were deployed over a three-week period. Our analysis of demographic factors, effects of phishing email content, and effects of repeated exposure to phishing exploits revealed significant age effects, marginally significant gender differences, and significant differences in email type. A multi-level model estimated effects of multiple variables simultaneously

    Effects of syndication network on specialisation and performance of venture capital firms

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    The Chinese venture capital (VC) market is a young and rapidly expanding financial subsector. Gaining a deeper understanding of the investment behaviours of VC firms is crucial for the development of a more sustainable and healthier market and economy. Contrasting evidence supports that either specialisation or diversification helps to achieve a better investment performance. However, the impact of the syndication network is overlooked. Syndication network has a great influence on the propagation of information and trust. By exploiting an authoritative VC dataset of thirty-five-year investment information in China, we construct a joint-investment network of VC firms and analyse the effects of syndication and diversification on specialisation and investment performance. There is a clear correlation between the syndication network degree and specialisation level of VC firms, which implies that the well-connected VC firms are diversified. More connections generally bring about more information or other resources, and VC firms are more likely to enter a new stage or industry with some new co-investing VC firms when compared to a randomised null model. Moreover, autocorrelation analysis of both specialisation and success rate on the syndication network indicates that clustering of similar VC firms is roughly limited to the secondary neighbourhood. When analysing local clustering patterns, we discover that, contrary to popular beliefs, there is no apparent successful club of investors. In contrast, investors with low success rates are more likely to cluster. Our discoveries enrich the understanding of VC investment behaviours and can assist policymakers in designing better strategies to promote the development of the VC industry

    A Novel Sliding Mode Control Technique for Indirect Current Controlled Active Power Filter

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    A novel sliding mode control (SMC) method for indirect current controlled three-phase parallel active power filter is presented in this paper. There are two designed closed loops in the system: one is the DC voltage controlling loop and the other is the reference current tracking loop. The first loop with a PI regulator is used to control the DC voltage approximating to the given voltage of capacitor, and the output of PI regulator through a low-pass filter is applied as the input of the power supply reference currents. The second loop implements the tracking of the reference currents using integral sliding mode controller, which can improve the harmonic treating performance. Compared with the direct current control technique, it is convenient to be implemented with digital signal processing system because of simpler system structure and better harmonic treating property. Simulation results verify that the generated reference currents have the same amplitude with the load currents, demonstrating the superior harmonic compensating effects with the proposed shunt active power filter compared with the hysteresis method

    P14AS upregulates gene expression in the CDKN2A/2B locus through competitive binding to PcG protein CBX7

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    Background: It is well known that P16INK4A, P14ARF, P15INK4B mRNAs, and ANRIL lncRNA are transcribed from the CDKN2A/2B locus. LncRNA P14AS is a lncRNA transcribed from antisense strand of P14ARF promoter to intron-1. Our previous study showed that P14AS could upregulate the expression level of ANRIL and P16INK4A and promote the proliferation of cancer cells. Because polycomb group protein CBX7 could repress P16INK4A expression and bind ANRIL, we wonder whether the P14AS-upregulated ANRIL and P16INK4A expression is mediated with CBX7.Results: In this study, we found that the upregulation of P16INK4A, P14ARF, P15INK4B and ANRIL expression was induced by P14AS overexpression only in HEK293T and HCT116 cells with active endogenous CBX7 expression, but not in MGC803 and HepG2 cells with weak CBX7 expression. Further studies showed that the stable shRNA-knockdown of CBX7 expression abolished the P14AS-induced upregulation of these P14AS target genes in HEK293T and HCT116 cells whereas enforced CBX7 overexpression enabled P14AS to upregulate expression of these target genes in MGC803 and HepG2 cells. Moreover, a significant association between the expression levels of P14AS and its target genes were observed only in human colon cancer tissue samples with high level of CBX7 expression (n = 38, p < 0.05), but not in samples (n = 37) with low level of CBX7 expression, nor in paired surgical margin tissues. In addition, the results of RNA immunoprecipitation (RIP)- and chromatin immunoprecipitation (ChIP)-PCR analyses revealed that lncRNA P14AS could competitively bind to CBX7 protein which prevented the bindings of CBX7 to both lncRNA ANRIL and the promoters of P16INK4A, P14ARF and P15INK4B genes. The amounts of repressive histone modification H3K9m3 was also significantly decreased at the promoters of these genes by P14AS in CBX7 actively expressing cells.Conclusions: CBX7 expression is essential for P14AS to upregulate the expression of P16INK4A, P14ARF, P15INK4B and ANRIL genes in the CDKN2A/2Blocus. P14AS may upregulate these genes’ expression through competitively blocking CBX7-binding to ANRIL lncRNA and target gene promoters

    Subsurface Engineering Induced Fermi Level De-pinning in Metal Oxide Semiconductors for Photoelectrochemical Water Splitting

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    Photoelectrochemical (PEC) water splitting is a promising approach for renewable solar light conversion. However, surface Fermi level pinning (FLP), caused by surface trap states, severely restricts the PEC activities. Theoretical calculations indicate subsurface oxygen vacancy (sub-O-v) could release the FLP and retain the active structure. A series of metal oxide semiconductors with sub-O-v were prepared through precisely regulated spin-coating and calcination. Etching X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and electron energy loss spectra (EELS) demonstrated O-v located at sub similar to 2-5 nm region. Mott-Schottky and open circuit photovoltage results confirmed the surface trap states elimination and Fermi level de-pinning. Thus, superior PEC performances of 5.1, 3.4, and 2.1 mA cm(-2) at 1.23 V vs. RHE were achieved on BiVO4, Bi2O3, TiO2 with outstanding stability for 72 h, outperforming most reported works under the identical conditions

    Case report: Excessive daytime sleepiness as a presenting manifestation of autoimmune glial fibrillary acidic protein astrocytopathy

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    Autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) is a recently discovered autoimmune inflammatory disease of the central nervous system. It presents with a variety of clinical symptoms, including fever, seizures, psychiatric symptoms, limber weakness, and sensory symptoms. However, the symptoms of sleep disorders have not been sufficiently addressed. Here, we report a case of GFAP-A in which the patient complained of excessive daytime sleepiness and an excessive need for sleep. Our patient was a 58-year-old male who experienced excessive daytime sleepiness for 50 days following SARS-CoV-2 infection. He was diagnosed with coronavirus disease 2019 on June 1st. On the 7th of June, he experienced excessive daytime sleepiness, nausea, reduced food intake, lower limb weakness, and dysuria. Subsequently, his sleepiness significantly deteriorated on July 21st. Five months prior, the patient underwent laparoscopic partial right nephrectomy for clear-cell renal cell carcinoma. Brain MRI revealed abnormal hyperintense lesions in the pontine brain and around the mesencephalic aqueduct on T2 and T2-fluid attenuated inversion recovery (T2-FLAIR) sequences However, these lesions did not exhibit any pathological enhancement. Spinal cord MRI revealed lesions in the C6–C7 and T2–T3 segments on the T2 sequence. His Epworth Sleepiness Scale (ESS) score was 16 (reference range, <10), and 24-hour polysomnography supported the diagnosis of rapid-eye-movement sleep disorder and severe sleep apnea-hypopnea syndrome. Glial fibrillary acidic protein IgG antibodies were detected in the cerebrospinal fluid (1:32, cell-based assay) but not in the serum. The level of hypocretin in the cerebrospinal fluid was 29.92 pg/mL (reference range ≥110 pg/mL), suggesting narcolepsy type 1. After treatment with corticosteroids for approximately 1 month, the patient showed considerable clinical and radiological improvement, as well as an increase in hypocretin levels. Although repeated polysomnography and multiple sleep latency tests suggested narcolepsy, his ESS score decreased to 8. Our findings broaden the range of clinical manifestations associated with GFAP-A, thereby enhancing diagnostic and therapeutic strategies for this disease. Additionally, our results indicate a potential common autoimmune mechanism involving GFAP-A and orexin system dysregulation, warranting further investigation

    FOXL2 and DMRT1L Are Yin and Yang Genes for Determining Timing of Sex Differentiation in the Bivalve Mollusk Patinopecten yessoensis

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    Sex determination and differentiation have long been a research hotspot in metazoans. However, little is known about when and how sex differentiation occurs in most mollusks. In this study, we conducted a combined morphological and molecular study on sex differentiation in the Yesso scallop Patinopecten yessoensis. Histological examination on gonads from 5- to 13-month-old juveniles revealed that the morphological sex differentiation occurred at 10 months of age. To determine the onset of molecular sex differentiation, molecular markers were screened for early identification of sex. The gonadal expression profiles of eight candidate genes for sex determination or differentiation showed that only two genes displayed sexually dimorphic expression, with FOXL2 being abundant in ovaries and DMRT1L in testes. In situ hybridization revealed that both of them were detected in germ cells and follicle cells. We therefore developed LOG10(DMRT1L/FOXL2) for scallop sex identification and confirmed its feasibility in differentiated individuals. By tracing its changes in 5- to 13-month-old juveniles, molecular sex differentiation time was determined: some scallops differentiate early in September when they are 7 months old, and some do late in December when they are 10 months old. Two kinds of coexpression patterns were found between FOXL2 and DMRT1L: expected antagonism after differentiation and unexpected coordination before differentiation. Our results revealed that scallop sex differentiation co-occurs with the formation of follicles, and molecular sex differentiation is established prior to morphological sex differentiation. Our study will assist in a better understanding of the molecular mechanism underlying bivalve sex differentiation

    Development of Mass Spectrometric Methods for the Analysis of Base Oils and Jet Fuels and for the Experimental Measurement of Proton Affinities of Alkanes

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    Petroleum products, such as base oils and jet fuels, play an essential role in modern society since they are necessary as lubricants for engines and as fuels for airplanes. The ability to accurately characterize these petroleum products is crucial for the successful generation of these compound mixtures with desirable properties. Unfortunately, analysis of petroleum products remains challenging due to the fact that they often contain thousands of different hydrocarbons. The petroleum industry relies heavily on powerful analytical techniques to evaluate the chemical compositions of petroleum products in order to improve their crude oil refinery procedures. Tandem mass spectrometry is the only analytical technique that has the potential to provide both elemental composition and structural information for individual analytes in complex mixtures. When coupled to chromatography, different tandem mass spectrometry methods facilitate the analysis of individual hydrocarbons in complex mixtures and therefore provide more detailed compositional information for petroleum products than other analytical methods. Fundamental studies that explore the physical and chemical properties of hydrocarbons also facilitate the development of new mass spectrometric ionization techniques for these analytes. The research discussed in this dissertation can be divided into three parts: the development and validation of new quantitation methodology for compounds representing twelve different hydrocarbon types in jet fuels (Chapters 3), the comparison of (+)APCI MS and GCxGC/(+)EI TOF MS for the analysis of saturated and aromatic hydrocarbons in group III heavy base oils (Chapter 4), and experimental measurement of proton affinities of alkanes (Chapter 5)

    Two-Stage Nested Array Direction of Arrival Estimation for Mixed Signals

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    In this paper, a novel two-stage subspace-based direction of arrival (DOA) estimation algorithm with the nested array is proposed for mixed signals containing circular and non-circular ones. By exploiting the difference between the two types of steering vectors, the DOAs of circular signals are estimated in the first stage. After eliminating the estimated information of circular signals by the covariance matrix reconstruction and oblique projection methods, the dimensions of the noise subspace are increased in estimating the DOAs of non-circular signals in the second stage. Through the two-stage estimation, the DOAs of the circular and non-circular signals are estimated separately and different types of signals with similar or the same DOAs can be distinguished. Furthermore, to avoid the two-dimensional (2-D) search with huge computational burden, a one-dimensional (1-D) search method exploiting the rank deficiency is proposed in the DOA estimation for non-circular signals. The simulation results show that the proposed algorithm can effectively improve the estimation accuracy and resolution probability, especially when circular and non-circular signals have similar DOAs
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