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Purpose: The prevalence of multimedia technology in the current educational settings has increased the need for investigating how individual differences such as reading difficulties moderate multimedia learning. Given that instructional designs closely interact with task characteristics and requirements, we aimed to explore how students with reading difficulties perform various types of learning tasks within the context of multimedia instruction.Methods: College students with and without reading difficulties viewed a multimedia lesson on stem cell research while their eye movements were recorded. After viewing the multimedia slides, students completed four tasks pertaining to the content provided in the lesson.Results: Students with reading difficulties performed poorer than their peers on the procedural task while the groups’ performance did not differ on definitional, infographic, and argumentative tasks. Further, there was no difference in the eye fixation counts and gaze duration between the two groups.Conclusions: Our findings underscore the importance of an awareness that the types of tasks used to assess students’ knowledge may impact their performance. Information of this nature may be useful in determining optimal learning experiences for students with learning difficulties.

The Global Neuronal Workspace (GNW) hypothesis states that the visual percept is available to conscious awareness only if recurrent long-distance interactions among distributed brain regions activate neural circuitry extending from posterior regions to prefrontal regions above a certain excitation threshold. To directly test this hypothesis, we trained human participants to increase blood oxygenation level-dependent (BOLD) signals with real-time functional magnetic resonance imaging (rtfMRI) based neurofeedback simultaneously in four specific regions of the occipital, temporal, insular and prefrontal parts of the brain. Specifically, we hypothesized that up-regulation of the mean BOLD activity in the posterior-frontal brain regions lowers the perceptual threshold for visual stimuli, while down-regulation raises the threshold. Our results showed that participants were able to perform up-regulation of the posterior-frontal brain activity but not down-regulation. Furthermore, the up-regulation training led to a significant reduction of the visual perceptual threshold, but no significant change of perceptual threshold was observed after down-regulation training. These findings partially support the GNW hypothesis of consciousness perception, to the extent that up-regulation of the posterior-frontal regions improves conscious awareness of stimuli. However, further questions as to whether the posterior-frontal regions can be down-regulated at all, and whether down-regulation raises the perceptual threshold remain unanswered.

Radio relics in the outskirts of galaxy clusters imply the diffusive shock acceleration (DSA) of electrons at merger-driven shocks with Mach number $M_{s}\lesssim3-4$ in the intracluster medium (ICM). Recent studies have suggested that electron preacceleration and injection, prerequisite steps for DSA, could occur at supercritical shocks with $M_{s}\gtrsim2.3$ in the ICM, thanks to the generation of multiscale waves by microinstabilities such as the Alfv\'en ion cyclotron (AIC) instability, the electron firehose instability (EFI), and the whistler instability (WI). On the other hand, some relics are observed to have subcritical shocks with $M_{s}\lesssim2.3$, leaving DSA at such weak shocks as an outstanding problem. Reacceleration of preexisting nonthermal electrons has been contemplated as one of possible solutions for that puzzle. To explore this idea, we perform Particle-in-Cell (PIC) simulations for weak quasi-perpendicular shocks in high-$\beta$ ($\beta=P_{\rm gas}/P_{B}$) plasmas with power-law suprathermal electrons in addition to Maxwellian thermal electrons. We find that suprathermal electrons enhance the excitation of electron-scale waves via the EFI and WI. However, they do not affect the ion reflection and the ensuing generation of ion-scale waves via the AIC instability. The presence of ion-scale waves is the key for the preacceleration of electrons up to the injection momentum, thus the shock criticality condition for electron injection to DSA is preserved. Based on the results, we conclude that preexisting nonthermal electrons in the preshock region alone would not resolve the issue of electron preacceleration at subcritical ICM shocks., Comment: 12 pages, 7 figures, to appear in ApJ

In the current investigation, two studies were designed to examine the effects of learner’s individual cognitive differences and presentation types on students’ learning, using an experimental research design. Prior to the participation in one of two studies, college students were tested on measures of verbal ability, visual memory, and background knowledge. In the first study, 114 students were presented with narration-based lessons (narration + image or narration-only) while in the second study, 190 students were presented with text-based lessons (text + image, text + image + narration, or text-only) followed by comprehension questions. In both studies, verbal ability was a strong concurrent predictor of learning outcomes irrespective of the type of instructional media. Behavioral and eye-gaze data indicated that multimedia presentations resulted in better learning outcome than single media presentations both in the narration-based and text-based conditions and that redundant presentations of information did not improve learning. Findings support the use of multimedia instructional platforms in conjunction with strengthening students’ verbal skills. https://doi.org/10.26803/ijlter.18.1.6

Radio relics associated with merging galaxy clusters indicate the acceleration of relativistic electrons in merger-driven shocks with low sonic Mach numbers ($M_{\rm s}\lesssim 3$) in the intracluster medium (ICM). Recent studies have suggested that electron injection to diffusive shock acceleration (DSA) could take place through the so-called Fermi-like acceleration in the shock foot of $\beta=P_{\rm gas}/P_{\rm B}\approx 20-100$ shocks and the stochastic shock drift acceleration (SSDA) in the shock transition of $\beta\approx 1-5$ shocks. Here we explore how the SSDA can facilitate electron preacceleration in weak quasi-perpendicular ($Q_{\perp}$) shocks in $\beta\approx 20-100$ plasmas by performing particle-in-cell simulations in the two-dimensional domain large enough to encompass ion-scale waves. We find that in supercritical shocks with $M_{\rm s}\gtrsim M_{\rm AIC}^*\sim 2.3$, multi-scale waves are excited by the ion and electron temperature anisotropies in the downstream of the shock ramp, and that through stochastic pitch-angle scattering off the induced waves, electrons are confined in the shock transition for an extended period. Gaining energy through the gradient-drift along the motional electric field, electrons could be preaccelerated all the way to injection to DSA at such ICM shocks. Our findings imply that the electron DSA process at weak ICM shocks could explain the origin of radio relics. However, a further investigation of electron acceleration at subcritical shocks with $M_{\rm s}< 2.3$ is called for, since the Mach numbers of some observed radio relic shocks derived from radio or X-ray observations are as low as $M_{\rm s}\sim 1.5$., Comment: 17 pages, 9 figures, to appear in ApJ

Prosthetic joint infection (PJI) is one of the most devastating failures in total joint replacement (TJR). Infections are becoming difficult to treat due to the emergence of multi-drug resistant bacteria. These bacteria produce biofilm on the implant surface, rendering many antibiotics ineffective by compromising drug diffusion and penetration into the infected area. With the introduction of new antibiotics there is a need to create benchmark data from the traditional antibiotic loaded bone cements. Vancomycin, one of the commonly used antibiotics, shows activity against Methicillin-resistant Staphylococcus aureus (MRSA) and S.epidermidis. In our study, vancomycin added to bone cement was evaluated for elution properties, antimicrobial properties, and mechanical properties of the bone cement. Vancomycin at five different loading masses (0.125, 0.25, 0.5, 1.0 and 2.0 g) was added to 40 g of Simplex™ P cement. Addition of vancomycin affected the mechanical properties and antimicrobial activity with significant differences from controls. Flexural and compression mechanical properties were compromised with added vancomycin. The flexural strength of samples with added vancomycin of 0.5 g and greater were not greater than ISO 5833 minimum requirements. 2.0 g of vancomycin added to bone cement was able to eliminate completely the four bacterial strains tested. 2.0 g of vancomycin also showed the highest mass elution from the cement over a 60-day period. Given the reduced flexural strength in samples with 0.5 g and greater of added vancomycin and the inability of vancomycin in amounts less than 2.0 g to eliminate bacteria, this study did not find an ideal amount of vancomycin added to Simplex™ P that meets both strength and antibacterial requirements.

Infection incidence for total hip and knee arthroplasty (THA and TKA, respectively) is between 0.2% and 5% and results in approximately 100,000 device failures per year in the United States. Treatment requires prolonged systemic antibiotic therapy with additional surgical revisions. As a prophylactic measure against infection, antibiotics can be incorporated into bone cement during THA and TKA to provide drug administration at the implant site. Antibiotics in bone cement are only effective if they can elute out of the cement at a concentration that is active against common organisms. There is evidence that added antibiotics may affect the cement's mechanical properties, especially at higher dosages. The purposes of this investigation were to (i) determine the mechanical properties of a commercially available bone cement with the addition of vancomycin, (ii) determine the release characteristics of vancomycin added to bone cement, and (iii) evaluate eluted vancomycin efficacy at eliminating some of the most common causative orthopedic implant pathogens. Palacos bone cement was impregnated with incrementally larger clinically relevant weight percentages of vancomycin. Vancomycin is a treatment standard for invasive gram-positive infections, and Palacos cement is one of the most commonly used bone cements. After 21 days of curing in PBS, added masses of vancomycin greater than 0.5 g per 40.0 g cement packet decreased the cement's compressive yield strength to below ISO standard. The addition of vancomycin reduced the bone cement's mechanical properties in compression more than in bending. Vancomycin eluted from Palacos with a steady rise in eluted volume up to 8 days, after which non-therapeutic elution concentrations were observed up to a 60-day end point. The eluted concentration from samples with greater than 0.25 g vancomycin per Palacos packet was sufficient to eliminate a 103 colony forming unit per mL (CFU/mL) initial inoculum of S. aureus, including methicillin-resistant S. aureus (MRSA). However, none of the tested dosages were able to fully clear a 103 CFU/mL initial inoculum of a known high biofilm producing strain of S. epidermidis. When used for infection prophylaxis at the time of THA and TKA, the findings of this study do not support the addition of more than 0.5 g vancomycin to a 40 g packet of Palacos cement due to a reduction in compression yield strength below ISO standards. Vancomycin doses up to 0.5 g were shown to elute from the bone cement matrix and are effective at treating bacterial infections of 103 CFU/mL in bacterial strains of S. aureus, but may have limited effect against high-biofilm producing strains including S. epidermidis.

A long-standing hypothesis is that rapid automatized naming (RAN) measures access to phonological representations stored in long-term memory, but this has been difficult to test experimentally because phonological representations are mental constructs not easily operationalized. Here, we provide a method to test this theory using rime neighborhood density as an index of phonological representational strength. Thirty adults completed four picture-naming tasks orthogonalized for item composition (repeating vs. nonrepeating) and presentation format (discrete vs. serial). Each task was presented in two dichotomous conditions of rime neighborhood density (dense and sparse). There was no effect of rime neighborhood density on naming speed in the discrete nonrepeated (confrontation naming) task. However, rime neighborhood density significantly facilitated naming speed for serial repeated (i.e., RAN), discrete repeated, and serial nonrepeated tasks (psd=0.14) and strongest for both discrete and serial RAN tasks (ds=1.01), suggesting that repeating items, not serial presentation, makes RAN uniquely sensitive to manipulations of rime neighborhood density and, by proxy, phonological representations.

In this article, we report data on the antibiotic elution and efficacy, and mechanical properties of Palacos bone cement with different amounts of added vancomycin (0.0, 0.125, 0.25, 0.5, 1.0, 2.0 g), see “Vancomycin elution, activity and impact on mechanical properties when added to orthopedic bone cement” (Bishop et al., 2018) [1] . Mechanical testing was performed for four-point bending, compression, and fracture toughness. The release characteristics of vancomycin was recorded for up to 60 days to estimate the elution profile. The eluted vancomycin efficacy at eliminating the four most common causative orthopedic implant pathogens is also reported.

Prosthetic joint infection (PJI) is the most common reason for early revision of total joint replacements. In these applications, antibiotic-loaded bone cement (ALBC) is widely used both as a prophylaxis and treatment/management for PJI. However, over time, the bacterial strains most frequently associated with PJI have become resistant to the antibiotics commonly used in ALBC's such as gentamicin and vancomycin. The present study was an in vitro evaluation of telavancin-loaded Palacos R and Simplex P cements, with different amounts of the antibiotic added to 40 g of cement powder: 0.125, 0.25, 0.5, 1.0, and 2.0 g. Telavancin elution was measured from each cement over 60 days. The efficacy of the eluted telavancin in eliminating four bacterial strains associated with PJI (MSSA, MRSA, and S. epidermidis) was determined. Mechanical tests, four-point bend, compression, and fracture toughness, were performed. In this in vitro study, the higher doses of telavancin increased telavancin release, and Palacos exhibited better elution than did Simplex. Similarly, the addition of 2 g of telavancin to the Palacos increased the efficacy of the ALBC for preventing bacterial colonization and biofilm formation. However, the mechanical performance of the bone cement containing telavancin was significantly reduced after wet curing, with flexural and compressive strength of the cements weakening. Moreover, Palacos that contained telavancin resulted in higher fracture toughness than did Simplex. Therefore, incorporating telavancin into Palacos for use in total joint replacement surgery demonstrated better performance than Simplex but further study is needed to improve the detrimental effects on mechanical properties.

Direct copper (Cu) electrodeposition on a 10-nm atomic-layer-deposited (ALD) tungsten carbide (WC) diffusion barrier layer was investigated for building Cu interconnect in silicon (Si)-based microelectronic devices. The diffusion of Cu reducing species under potentiostatic Cu deposition was characterized according to applied cathodic potential in a neutral electrolyte with a concentration ratio of 1:10 for Cu to iminodiacetic acid (IDA) as a complexing agent. The diffusion-controlled nucleation and growth of Cu thin film on the ALD WC was figured out in relation to diffusion coefficients of Cu reducing species that were calculated from both modified current transient curves and more appropriately electrochemical impedance spectroscopy (EIS) analysis. At the end, the diffusion-controlled Cu fill of trenches with an aspect ratio of 6.3 and 15-nm bottom width was conducted by applying −1.4 V vs Ag/AgCl to an ALD-WC-covered, patterned Si wafer specimen.

We investigated the conduction characteristics of plasma-doped Si nanowires (NWs) after various rapid thermal annealing (RTA) times. The plasma doping (PD) process developed a highly-deposited B layer at the NW surface. RTA process controls electrical conductivity by mediating the dopant diffusion from the surface layer. The surface chemical and substitutional states of the B plasma-doped Si NWs were analyzed by x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. To elucidate the detailed structure of the NWs, we analyzed the change in the optical phonon mode caused by the incorporated B atoms. For this purpose, we examined Fano resonance by the investigation of the asymmetry, line-width, and phonon wavenumber in Raman spectra. The changes in symmetry level of the Raman peak, phonon lifetime, and internal strain were closely related to the number of electrically activated borons, which was drastically increased with RTA time. The change in electrical and optical characterizations related to the doping characteristics of the NWs was investigated using a 4-point probe and terahertz time-domain spectroscopy (THz–TDS). The resistivity of the NWs was 3000 times lower after the annealing process compared to that before the annealing process, which is well consistent with the optical conductivity data. The data provide the potential utility of PD in conformal doping for three-dimensional nanodevices.

Cu was electrodeposited directly on a 3-nm-thick atomic-layer-deposited (ALD) Ru diffusion barrier layer in Cu-citrate-based electrolytes for Cu interconnect. The nucleation and growth behavior of Cu thin films on the ALD Ru was compared between an additive-free electrolyte and a polyethylene glycol (PEG)/janus green B (JGB)-added electrolyte. The suppression effect of additives in the PEG/JGB-added electrolyte led to lower Cu deposition rate. It was accordingly responsible for the growth of thin and uniform Cu films from smaller Cu nuclei of higher area density. In consequence, Cu filling of 30-nm-wide and 120-nm-deep trenches coated by the 3-nm-thick ALD Ru layer was much improved in the PEG/JGB-added electrolyte compared with the additive-free electrolyte.

Van Allen radiation belt is characterized by energetic electrons and ions trapped in the Earth's dipolar magnetic field lines and persisting for long periods. It is also permeated by high-frequency electrostatic fluctuations whose peak intensity occurs near the upper hybrid frequency. Such a phenomenon can be understood in terms of spontaneous emission of electrostatic multiple harmonic electron cyclotron waves by thermal plasmas. In the literature, the upper hybrid fluctuations are used as a proxy for determining the electron number density, but they also contain important information concerning the energetic electrons in the radiation belt and possibly the ring current electrons. The companion paper analyzes sample quiet time events and demonstrates that the upper hybrid fluctuations are predominantly emitted by tenuous population of energetic electrons. The present paper supplements detailed formalism of spontaneous thermal emission of multiple-harmonic cyclotron waves that include upper hybrid fluctuations.

For Cu interconnect in Si-based microelectronic devices, seedless electrodeposition of Cu thin films directly on Ti diffusion barrier was investigated in Cl-free, citrate (Cit)-based acidic electrolytes with polyethylene glycol (PEG) or Janus Green B (JGB) additive. Both PEG and JGB suppressed Cu electrodeposition on the Ti surface effectively, and even their inhibition against Cu-Cit complex reduction was synergetic. Accordingly they decreased the surface roughness of Cu thin film on the Ti surface considerably. Thus, seedless growth of Cu thin films on Ti was achieved from the synergistic leveling effect of both PEG and JGB in the absence of Cl because PEG adsorption onto the Ti surface did not accompany PEG complexation with Cl and Cu+, and CuCl contamination did not occur. 3D nucleation of Cu on the Ti surface became more progressive in more additive-concentrated electrolytes. Good interfacial adhesion between Cu thin film and Ti diffusion barrier was maintained, whereas the sheet resistance of Cu thin films was fairly increased, in spite of adding PEG and JGB. Display Omitted

A growing body of research suggests that individuals with dyslexia struggle to use graphs efficiently. Given the persistence of orthographic processing deficits in dyslexia, this study tested whether graph interpretation deficits in dyslexia are directly related to difficulties processing the orthographic components of graphs (i.e. axes and legend labels). Participants were 80 college students with and without dyslexia. Response times and eye movements were recorded as students answered comprehension questions about simple data displayed in bar graphs. Axes and legends were labelled either with words (mixed-modality graphs) or icons (orthography-free graphs). Students also answered informationally equivalent questions presented in sentences (orthography-only condition). Response times were slower in the dyslexic group only for processing sentences. However, eye tracking data revealed group differences for processing mixed-modality graphs, whereas no group differences were found for the orthography-free graphs. When processing bar graphs, students with dyslexia differ from their able reading peers only when graphs contain orthographic features. Implications for processing informational text are discussed. Copyright © 2017 John Wiley & Sons, Ltd.

Slightly tapered Si1−xGex nanowires (NWs) (x = 0.29–0.84) were synthesized via a vapor–liquid–solid procedure using Au as a catalyst. We measured the optically excited carrier dynamics of Si1−xGex NWs as a function of Ge content using optical pump–THz probe spectroscopy. The measured −ΔT/T0 signals of Si1−xGex NWs were converted into conductivity in the THz region. We developed a fitting formula to apply to indirect semiconductors such as Si1−xGex, which explains the temporal population of photo-excited carriers in the band structure and the relationship between the trapping time and the defect states on an ultrafast time scale. From the fitting results, we extracted intra- and inter-valley transition times and trapping times of electrons and holes of Si1−xGex NWs as a function of Ge content. On the basis of theoretical reports, we suggest a physical model to interpret the trapping times related to the species of interface defect states located at the oxide/NW: substoichiometric oxide states of Si(Ge)0+,1+,2+, but not Si(Ge)3+, could function as defect states capturing photo-excited electrons or holes and could determine the different trapping times of electrons and holes depending on negatively or neutrally charged states.