Investigation of the use of navigation tools in web-based learning: A data mining approach

Web-based learning is widespread in educational settings. The popularity of Web-based learning is in great measure because of its flexibility. Multiple navigation tools provided some of this flexibility. Different navigation tools offer different functions. Therefore, it is important to understand how the navigation tools are used by learners with different backgrounds, knowledge, and skills. This article presents two empirical studies in which data-mining approaches were used to analyze learners' navigation behavior. The results indicate that prior knowledge and subject content are two potential factors influencing the use of navigation tools. In addition, the lack of appropriate use of navigation tools may adversely influence learning performance. The results have been integrated into a model that can help designers develop Web-based learning programs and other Web-based applications that can be tailored to learners' needs

Detecting Fraud in Chinese Listed Company Balance Sheets

This study investigates the links between accounting values in Chinese listed companies’ balance sheets and the exposure of their fraudulent activities. Every balance sheet account is proposed to be a potential vehicle to manipulate financial statements. Other receivables, inventories, prepaid expenses, employee benefits payables and long-term payables are important indicators of fraudulent financial statements. These results confirm that asset account manipulation is frequently carried out and cast doubt on earlier conclusions by researchers that inflation of liabilities is the most common source of financial statement manipulation. Prior practices of solely scaling balance sheet values by assets are revealed to produce spurious relationships, while scaling by both assets and sales effectively detects fraudulent financial statements and provides a useful fraud prediction tool for Chinese auditors, regulators and investors

Rapid phosphorylation of the CRE binding protein precedes stress-induced activation of the corticotropin releasing hormone gene in medial parvocellular hypothalamic neurons of the immature rat.

The mechanisms of the molecular and neuroendocrine responses to stress in the immature rat have been a focus of intense investigation. A principal regulator of the these responses in both mature and developing rat is the neuropeptide corticotropin releasing hormone (CRH), and levels of hypothalamic CRH mRNA are enhanced by stress. In vitro, transcription of the CRH gene is governed by binding of the phosphorylated form of cAMP responsive element binding protein (pCREB) to the promoter. Here we tested the hypothesis that rapid, stress-induced CRH transcription occurred during the first two postnatal weeks, and is associated with pCREB expression. The time-course of induction of unedited, heteronuclear CRH RNA (CRH hnRNA) was examined in hypothalamic paraventricular nucleus (PVN) of immature rats subjected to both modest and strong acute stressors using in situ hybridization; pCREB abundance was determined in individual neurons in specific PVN sub-nuclei using immunocytochemistry and unbiased quantitative analysis. CRH hnRNA signal was negligible in PVN of immature rats sacrificed under stress-free conditions, but was readily detectable within 2 min, and peaked at 15 min, in PVN of stressed animals. Enhanced pCREB immunoreactivity was evident within 2 min of stress onset, and was enhanced specifically in stress-responsive, CRH-expressing medial parvocellular neurons. These data support the notion that, already during early postnatal life, stress induces rapid CREB phosphorylation, interaction of pCREB-containing transcription complexes with the CRE element of the CRH gene promoter, and initiation of CRH hnRNA production in stress-responsive neurons of rat PVN

Neuronal activity and stress differentially regulate hippocampal and hypothalamic corticotropin-releasing hormone expression in the immature rat.

Corticotropin-releasing hormone, a major neuromodulator of the neuroendocrine stress response, is expressed in the immature hippocampus, where it enhances glutamate receptor-mediated excitation of principal cells. Since the peptide influences hippocampal synaptic efficacy, its secretion from peptidergic interneuronal terminals may augment hippocampal-mediated functions such as learning and memory. However, whereas information regarding the regulation of corticotropin-releasing hormone's abundance in CNS regions involved with the neuroendocrine responses to stress has been forthcoming, the mechanisms regulating the peptide's levels in the hippocampus have not yet been determined. Here we tested the hypothesis that, in the immature rat hippocampus, neuronal stimulation, rather than neuroendocrine challenge, influences the peptide's expression. Messenger RNA levels of corticotropin-releasing hormone in hippocampal CA1, CA3 and the dentate gyrus, as well as in the hypothalamic paraventricular nucleus, were determined after cold, a physiological challenge that activates the hypothalamic pituitary adrenal system in immature rats, and after activation of hippocampal neurons by hyperthermia. These studies demonstrated that, while cold challenge enhanced corticotropin-releasing hormone messenger RNA levels in the hypothalamus, hippocampal expression of this neuropeptide was unchanged. Secondly, hyperthermia stimulated expression of hippocampal immediate-early genes, as well as of corticotropin-releasing hormone. Finally, the mechanism of hippocampal corticotropin-releasing hormone induction required neuronal stimulation and was abolished by barbiturate administration. Taken together, these results indicate that neuronal stimulation may regulate hippocampal corticotropin-releasing hormone expression in the immature rat, whereas the peptide's expression in the hypothalamus is influenced by neuroendocrine challenges

Unusual Formation of Point-Defect Complexes in the Ultrawide-Band-Gap Semiconductor β-Ga2 O3

Understanding the unique properties of ultra-wide band gap semiconductors requires detailed information about the exact nature of point defects and their role in determining the properties. Here, we report the first direct microscopic observation of an unusual formation of point defect complexes within the atomic-scale structure of β-Ga2O3 using high resolution scanning transmission electron microscopy (STEM). Each complex involves one cation interstitial atom paired with two cation vacancies. These divacancy-interstitial complexes correlate directly with structures obtained by density functional theory, which predicts them to be compensating acceptors in β-Ga2O3. This prediction is confirmed by a comparison between STEM data and deep level optical spectroscopy results, which reveals that these complexes correspond to a deep trap within the band gap, and that the development of the complexes is facilitated by Sn doping through increased vacancy concentration. These findings provide new insight on this emerging material's unique response to the incorporation of impurities that can critically influence their properties

Capacitated Center Problems with Two-Sided Bounds and Outliers

In recent years, the capacitated center problems have attracted a lot of research interest. Given a set of vertices $V$, we want to find a subset of vertices $S$, called centers, such that the maximum cluster radius is minimized. Moreover, each center in $S$ should satisfy some capacity constraint, which could be an upper or lower bound on the number of vertices it can serve. Capacitated $k$-center problems with one-sided bounds (upper or lower) have been well studied in previous work, and a constant factor approximation was obtained. We are the first to study the capacitated center problem with both capacity lower and upper bounds (with or without outliers). We assume each vertex has a uniform lower bound and a non-uniform upper bound. For the case of opening exactly $k$ centers, we note that a generalization of a recent LP approach can achieve constant factor approximation algorithms for our problems. Our main contribution is a simple combinatorial algorithm for the case where there is no cardinality constraint on the number of open centers. Our combinatorial algorithm is simpler and achieves better constant approximation factor compared to the LP approach

Mechanism for controlling the monomer-dimer conversion of SARS coronavirus main protease

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Photocrosslinkable laminin-functionalized polyethylene glycol hydrogel for intervertebral disc regeneration

Intervertebral disc (IVD) disorders and age-related degeneration are believed to contribute to lower back pain. There is significant interest in cell-based strategies for regenerating the nucleus pulposus (NP) region of the disc; however, few scaffolds have been evaluated for their ability to promote or maintain an immature NP cell phenotype. Previous studies have shown that NP cell-laminin interactions promote cell adhesion and biosynthesis, which suggests a laminin-functionalized biomaterial may be useful for promoting or maintaining the NP cell phenotype. Here, a photocrosslinkable poly(ethylene glycol)-laminin 111 (PEG-LM111) hydrogel was developed. The mechanical properties of PEG-LM111 hydrogel could be tuned within the range of dynamic shear moduli values previously reported for human NP. When primary immature porcine NP cells were seeded onto PEG-LM111 hydrogels of varying stiffnesses, LM111-presenting hydrogels were found to promote cell clustering and increased levels of sGAG production as compared to stiffer LM111-presenting and PEG-only gels. When cells were encapsulated in 3-D gels, hydrogel formulation was found to influence NP cell metabolism and expression of proposed NP phenotypic markers, with higher expression of N-cadherin and cytokeratin 8 observed for cells cultured in softer (<1 kPa) PEG-LM111 hydrogels. Overall, these findings suggest that soft, LM111-functionalized hydrogels may promote or maintain the expression of specific markers characteristic of an immature NP cell phenotype. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

M2-M5 blackfold funnels

We analyze the basic M2-M5 intersection in the supergravity regime using the blackfold approach. This approach allows us to recover the 1/4-BPS self-dual string soliton solution of Howe, Lambert and West as a three-funnel solution of an effective fivebrane worldvolume theory in a new regime, the regime of a large number of M2 and M5 branes. In addition, it allows us to discuss finite temperature effects for non-extremal self-dual string soliton solutions and wormhole solutions interpolating between stacks of M5 and anti-M5 branes. The purpose of this paper is to exhibit these solutions and their basic properties.Comment: 19 pages, 5 figures, harvmac; typo corrected in equation (3.19

On single and double soft behaviors in NLSM

In this paper, we study the single and double soft behaviors of tree level off-shell currents and on-shell amplitudes in nonlinear sigma model(NLSM). We first propose and prove the leading soft behavior of the tree level currents with a single soft particle. In the on-shell limit, this single soft emission becomes the Adler's zero. Then we establish the leading and sub-leading soft behaviors of tree level currents with two adjacent soft particles. With a careful analysis of the on-shell limit, we obtain the double soft behaviors of on-shell amplitudes where the two soft particles are adjacent to each other. By applying Kleiss-Kuijf (KK) relation, we further obtain the leading and sub-leading behaviors of amplitudes with two nonadjacent soft particles.Comment: 41 pages, 6 tables, 9 figures, minor revised, more content about nonadjacent double soft limit, update the reference