The Role of Information Technology in Technology-Mediated Learning: A Review of the Past for the Future

Technology-mediated learning refers to an environment in which the learner\u27s interactions with learning materials, peers, and/or instructors are mediated through information technologies (Alavi and Leidner, 2001). The objective of this paper is to review current research on technology-mediated learning using a theoretical framework derived from the existing literature. The framework presents three dimensions (primary participant, instructional design, and information technology) that influence students\u27 psychological learning processes, and eventually lead to different learning outcomes. The literature review reveals that certain relationships identified by this framework have received significant attention (e.g., the influence of a technology feature on learning outcomes), while others have been ignored (e.g., the influence of IT on psychological processes). Research questions that can help advance our understanding of technology-mediated learning are discussed

Transition radiation by matter-wave solitons in optical lattices

We demonstrate that matter-wave solitary pulses formed from Bose condensed atoms moving inside optical lattices continuously radiate dispersive matter waves with prescribed momentum. Our analytical results for the radiation parameters and the soliton decay rate are found to be in excellent agreement with numerical modelling performed for experimentally relevant parameters.Comment: accepted to PR

In vivo trafficking of endogenous opioid receptors

Studies on trafficking of endogenous opioid receptors in vivo are subject of the present review. In many of the in vivo studies, the use of semi-quantitative immuno-electron microscopy is the approach of choice. Endogenous opioid receptors display differential subcellular distributions with μ opioid receptor (MOPR) being mostly present on the plasma membrane and δ- and κ-opioid receptors (DOPR and KOPR, respectively) having a significant intracellular pool. Etorphine and DAMGO cause endocytosis of the MOPR, but morphine does not, except in some dendrites. Interestingly, chronic inflammatory pain and morphine treatment promote trafficking of intracellular DOPR to the cell surface which may account for the enhanced antinociceptive effects of DOPR agonists. KOPR has been reported to be associated with secretory vesicles in the posterior pituitary and translocated to the cell surface upon salt loading along with the release of vasopressin. The study of endogenous opioid receptors using in vivo models has produced some interesting results that could not have been anticipated in vitro. In vivo studies, therefore, are essential to provide insight into the mechanisms underlying opioid receptor regulation

Concrete with triphasic conductive materials for self-monitoring of cracking development subjected to flexure

In this study, the macro steel fiber (SF), carbon fiber (CF) and nano carbon black (NCB) as triphasic conductive materials were added into concrete, in order to improve the conductivity and ductility of concrete. The influence of NCB, SF and CF on the post crack behavior and conductivity of concrete was explored. The effect of the triphasic conductive materials on the self-diagnosing ability to the load–deflection property and crack widening of conductive concrete member subjected to bending were investigated. The relationship between the fractional change in surface impedance (FCR) and the crack opening displacement (COD) of concrete beams with conductive materials has been established. The results illustrated that there is a linear relationship between COD and FCR.National Natural Science Foundation of ChinaThe authors acknowledge the National Natural Science Foundation of China (Grant: 51578109), the National Natural Science Foundation of China (Grant: 51121005), and Fundaçãopara a Ciência e a Tecnologia (SFRH/BPD/22680/2005 ), the FEDER Funds through “Programa Operacional Factores de Competitividade - COMPETE" and by Portuguese Funds through FCT-within the Projects PEst-CMAT/UI0013/2011 and PTDC/MAT/112273/2009

Self-monitoring of freeze–thaw damage using triphasic electric conductive concrete

The effect of freeze–thaw cycles on concrete is of great importance for durability evaluation of concrete structures in cold regions. In this paper, damage accumulation was studied by following the fractional change of impedance (FCI) with number of freeze–thaw cycles (N). The nano-carbon black (NCB), carbon fiber (CF) and steel fiber (SF) were added to plain concrete to produce the triphasic electrical conductive (TEC) and ductile concrete. The effects of NCB, CF and SF on the compressive strength, flexural properties, electrical impedance were investigated. The concrete beams with different dosages of conductive materials were studied for FCI, N and mass loss (ML), the relationship between FCI and N of conductive concrete can be well defined by a first order exponential decay curve. It is noted that this nondestructive and sensitive real-time testing method is meaningful for evaluating of freeze–thaw damage in concrete.The authors acknowledge the National Natural Science Foundation of China (Grant: 51578109) and (Grant: 51121005), and Fundação para a Ciência e a Tecnologia (SFRH/BPD/22680/2005), the FEDER Funds through “Programa Operacional Factores de Competitividade - COMPETE" and by Portuguese Funds through FCT - within the Projects PEst-CMAT/UI0013/2011, PTDC/MAT/112273/2009

Use of top-down and bottom-up fourier transform ion cyclotron resonance mass spectrometry for mapping calmodulin sites modified by platinum anticancer drugs

Calmodulin (CaM) is a highly conserved, ubiquitous, calcium-binding protein; it binds to and regulates many different protein targets, thereby functioning as a calcium sensor and signal transducer. CaM contains 9 methionine (Met), 1 histidine (His), 17 aspartic acid (Asp), and 23 glutamine acid (Glu) residues, all of which can potentially react with platinum compounds; thus, one-third of the CaM sequence is a possible binding target of platinum anticancer drugs, which represents a major challenge for identification of specific platinum modification sites. Here, top-down electron capture dissociation (ECD) was used to elucidate the transition metal–platinum(II) modification sites. By using a combination of top-down and bottom-up mass spectrometric (MS) approaches, 10 specific binding sites for mononuclear complexes, cisplatin and [Pt(dien)Cl]Cl, and dinuclear complex [{cis-PtCl2(NH3)}2(μ-NH2(CH2)4NH2)] on CaM were identified. High resolution MS of cisplatin-modified CaM revealed that cisplatin mainly targets Met residues in solution at low molar ratios of cisplatin–CaM (2:1), by cross-linking Met residues. At a high molar ratio of cisplatin:CaM (8:1), up to 10 platinum(II) bind to Met, Asp, and Glu residues. [{cis-PtCl2(NH3)}2(μ-NH2(CH2)4NH2)] forms mononuclear adducts with CaM. The alkanediamine linker between the two platinum centers dissociates due to a trans-labilization effect. [Pt(dien)Cl]Cl forms {Pt(dien)}2+ adducts with CaM, and the preferential binding sites were identified as Met51, Met71, Met72, His107, Met109, Met124, Met144, Met145, Glu45 or Glu47, and Asp122 or Glu123. The binding of these complexes to CaM, particularly when binding involves loss of all four original ligands, is largely irreversible which could result in their failure to reach the target DNA or be responsible for unwanted side-effects during chemotherapy. Additionally, the cross-linking of cisplatin to CaM might lead to the loss of the biological function of CaM or CaM–Ca2+ due to limiting the flexibility of the CaM or CaM–Ca2+ complex to recognize target proteins or blocking the binding region of target proteins to CaM

Employee Knowledge Sharing in Highly Dispersed Organizations

ABSTRACT Advances in information and communication technology have enabled contemporary organizations to become increasingly dispersed. Knowledge sharing among highly dispersed employees has been widely regarded as an organizational challenge that, if not dealt with properly, would affect the organization' s competitive advantage. Based on the practice perspective of knowledge, this study aims to explore factors and mechanisms that facilitate or impede knowledge sharing among highly dispersed organizational employees. In this paper we analyze data collected from semi-structured interviews with twenty employees in a highly dispersed organization, to understand how employees share knowledge through their work practice in order to get work done. The methodology and data analysis plan is also described

Fibres for enhancing of the bond capacity between GFRP rebar and concrete

The effect of steel fibres (SF) and macro-polypropylene fibres (PPA) on the bond capacity between GFRP rebar and concrete has been studied in this work. A novel method using the equivalent bond strength to evaluate the bond toughness is proposed. In comparison with the bond property of GFRP rebar in plain concrete (PC) matrix, the investigation indicates that adding macro mono fibres or hybrid fibres into concrete can enhance both the bond strength and the bond toughness. Especially, the hybrid use of SF and PPA demonstrates a significant positive synergetic effect on the bond behavior of GFRP rebars in concrete. The results show that the bond capacity of GFRP rebars in concrete reinforced by hybrid fibres can be equivalent to that or better than that of steel rebar in plain concrete.The authors gratefully acknowledge the National Natural Science Foundation: Grants: 51078058 and 51121005, Fundação para a Ciência e a Tecnologia (SFRH/BPD/22680/2005) and The FEDER Funds through “Programa Operacional Factores de Competitividade - COMPETE” and by Portuguese Funds through FCT - within the Projects PEst-CMAT/UI0013/2011 and PTDC/MAT/112273/200