A VLT/FORS2 Multi-Slit Search for Lyman-alpha Emitting Galaxies at z~6.5

We present results from a deep spectroscopic search in the 9150A atmospheric window for z~6.5 Lyman-alpha emitting galaxies using the VLT/FORS2. Our multi-slit+narrow-band filter survey covers a total spatial area of 17.6 sq. arcmin in four different fields and reaches fluxes down to 5x10^(-18) erg/s/cm^2 (7 sigma detection). Our detection limit is significantly fainter than narrow-band searches at this redshift and fainter also than the unlensed brightness of Hu et al.'s HCM6A at z=6.56, and thus provides better overlap with surveys at much lower redshifts. Eighty secure emission line galaxies are detected. However, based on their clear continuum emission shortward of the line or the presence of multiple lines, none of these can be Ly-alpha emission at z~6.5. Our null result of finding no z~6.5 Ly-alpha emitters suggests that the number density of Ly-alpha emitters with L>2x10^(42) erg/s declines by ~2 between z~3 and z~6.5.Comment: accepted by ApJ Letters (originally submitted June 11, 2004

Synthesis and Characterization of K and Eu Binary Phosphides.

The synthesis, structural characterization, and optical properties of the binary Zintl phases of α-EuP₃, β-EuP₃, EuP₂, and α-K₄P₆ are reported in this study. These crystal structures demonstrate the versatility of P fragments with dimensionality varying from 0D (P₆ rings in α-K₄P₆) to 1D chains (EuP₂) to 2D layers (both EuP₃). EuP₂ is isostructural to previously reported SrP₂ and BaP₂ compounds. The thermal stabilities of the EuP₂ and both EuP₃ phases were determined using differential scanning calorimetry (DSC), with melting temperatures of 1086 K for the diphosphide and 1143 K for the triphosphides. Diffuse reflectance spectroscopy indicated that EuP₂ is an indirect semiconductor with a direct bandgap of 1.12(5) eV and a smaller indirect one, less than 1 eV. Both EuP₃ compounds had bandgaps smaller than 1 eV

N-Arachidonoyl Dopamine Modulates Acute Systemic Inflammation via Nonhematopoietic TRPV1.

N-Arachidonoyl dopamine (NADA) is an endogenous lipid that potently activates the transient receptor potential vanilloid 1 (TRPV1), which mediates pain and thermosensation. NADA is also an agonist of cannabinoid receptors 1 and 2. We have reported that NADA reduces the activation of cultured human endothelial cells by LPS and TNF-α. Thus far, in vivo studies using NADA have focused on its neurologic and behavioral roles. In this article, we show that NADA potently decreases in vivo systemic inflammatory responses and levels of the coagulation intermediary plasminogen activator inhibitor 1 in three mouse models of inflammation: LPS, bacterial lipopeptide, and polymicrobial intra-abdominal sepsis. We also found that the administration of NADA increases survival in endotoxemic mice. Additionally, NADA reduces blood levels of the neuropeptide calcitonin gene-related peptide but increases the neuropeptide substance P in LPS-treated mice. We demonstrate that the anti-inflammatory effects of NADA are mediated by TRPV1 expressed by nonhematopoietic cells and provide data suggesting that neuronal TRPV1 may mediate NADA's anti-inflammatory effects. These results indicate that NADA has novel TRPV1-dependent anti-inflammatory properties and suggest that the endovanilloid system might be targeted therapeutically in acute inflammation

A new transgenic reporter line reveals Wnt-dependent Snai2 re-expression and cranial neural crest differentiation in Xenopus

During vertebrate embryogenesis, the cranial neural crest (CNC) forms at the neural plate border and subsequently migrates and differentiates into many types of cells. The transcription factor Snai2, which is induced by canonical Wnt signaling to be expressed in the early CNC, is pivotal for CNC induction and migration in Xenopus. However, snai2 expression is silenced during CNC migration, and its roles at later developmental stages remain unclear. We generated a transgenic X. tropicalis line that expresses enhanced green fluorescent protein (eGFP) driven by the snai2 promoter/enhancer, and observed eGFP expression not only in the pre-migratory and migrating CNC, but also the differentiating CNC. This transgenic line can be used directly to detect deficiencies in CNC development at various stages, including subtle perturbation of CNC differentiation. In situ hybridization and immunohistochemistry confirm that Snai2 is re-expressed in the differentiating CNC. Using a separate transgenic Wnt reporter line, we show that canonical Wnt signaling is also active in the differentiating CNC. Blocking Wnt signaling shortly after CNC migration causes reduced snai2 expression and impaired differentiation of CNC-derived head cartilage structures. These results suggest that Wnt signaling is required for snai2 re-expression and CNC differentiation

Robustness of Image-Based Malware Analysis

In previous work, “gist descriptor” features extracted from images have been used in malware classification problems and have shown promising results. In this research, we determine whether gist descriptors are robust with respect to malware obfuscation techniques, as compared to Convolutional Neural Networks (CNN) trained directly on malware images. Using the Python Image Library (PIL), we create images from malware executables and from malware that we obfuscate. We conduct experiments to compare classifying these images with a CNN as opposed to extracting the gist descriptor features from these images to use in classification. For the gist descriptors, we consider a variety of classification algorithms including k-nearest neighbors, random forest, support vector machine, and multi-layer perceptron. We find that gist descriptors are more robust than CNNs, with respect to the obfuscation techniques that we consider

Content appraisal and age moderate the relationship between passive social media use and mental ill-being

An important distinction to make when assessing the impact of social media use on mental health is whether the use is passive (e.g., browsing) or active (e.g., posting). Recent research suggests that the connection between passive social media use and mental ill-being is inconsistent, with some research finding a significant negative association, while other research finds no such association. In the present research, we sought to investigate this relationship, as well as two potential moderators of this relationship: the subjective appraisal of social media content social media users consume (i.e., positively or negatively-appraised) and age of users. In a cross-sectional survey of Australian and United States Facebook users (N = 991), there was no direct relationship between passive use and mental ill-being, however user age and positive (but not negative) content appraisal were found to moderate the relationship between passive use and mental ill-being. Specifically, the relationship between passive use and mental ill-being became weaker as subjective positive appraisal increased, and it reversed to become negative at high levels of positive appraisal. Additionally, the positive relationship between passive use and mental ill-being became weaker as age of social media users increased, and the direction of this relationship became negative at the oldest ages of social media users. These results suggest that the relationship between social media use and mental ill-being is more nuanced than previous research suggests. In particular, higher amounts of passive Facebook use may have a less negative, or even a positive effect on social media users’ mental health when the content being (passively) consumed is positively appraised, or when users are older

Evaluating colour preference by using multidimensional approaches

Colour preference is a key factor in the design and evaluation of lighting systems, particularly with the emergence of multichannel LED systems which allow for greater control over the spectrum of light emitted and therefore the colour appearance of the illuminated objects. To more accurately and objectively measure colour preference, there has been a growing interest in the development of multidimensional evaluation algorithms that consider multiple dimensions of colour rendering, such as chroma and hue shift. The purpose of this study was to compare and evaluate the performance of different multidimensional evaluation algorithms for colour preference in lighting applications. Using computer-generated images of a coloured object displayed on a computer monitor under a fixed white point, we simulated the colour shifts of the object under different light sources and test subjects evaluated the results using a range of multidimensional methods. Our analysis revealed that there are significant differences in the performance of these algorithms, with some providing more accurate and reliable measures of colour preference than others. Considering all relevant criteria, genetic algorithms seem to provide the most promising approach, as they lead to a result quickly and reliably. These findings have important implications for the selection and use of multidimensional algorithms for evaluating colour preference in lighting, particularly in the context of multichannel LED systems, and can inform future research in this area

Applying Motivation Theories to the Design of Educational Technology

Although there has been a wealth of research exploring motivation within technological environments, few of these studies employ frameworks that are grounded in well-established theories of motivation. This paper brings rigorous theoretical frameworks of motivation to the study and design of educational technology. First, we outline key motivation constructs that compose Eccles and Wigfield’s Expectancy-Value theory and the Self-Determination theory and discuss their implications for education. Through a case study, we then illustrate how motivational theories informed the recent development of a virtual learning environment designed to promote students’ interest in and motivation to pursue science, technology, engineering, and mathematics careers. Finally, looking toward the future of mobile learning, we discuss the motivational affordances of personal and portable features of mobile handhelds