1,157 research outputs found
Bridging Learning Gaps In Media And Information Literacy Through Massive Open Online Course
This research focused on Grade 12 students who participated in a Massive Open Online Course (MOOC) in Media and Information Literacy (MIL) during the school year 2022-2023. The study involved 259 learners from Talipan National High School – Senior High School and employed a quantitative method with a descriptive research design. Input data included the average mean, mean percentage scores (MPS), and mastery level of students. The process involved collecting data from a summative test, item analysis, and grades/ratings from the online course. The average mean scores before the MOOC were distributed as follows: ABM-30.22, HUMSS-31.76, STEM-4.52, and TVL-20.26. Meanwhile, MPS before the MOOC were as follows: ABM-60.43, HUMSS-63.52, STEM-69.04, and TVL-40.41. However, the average mean scores after the MOOC showed the following results: ABM-28.42, HUMSS-48.69, STEM-33.61, and TVL-33.61. Lastly, MPS results after the MOOC revealed the following: ABM-58.83, HUMSS-97.38, and STEM as well as TVL obtained 67.22 and 47.32, respectively. The frequency-percentage distribution of the mastery level in the 50-item test before the MOOC showed that 21 items (42%) were least mastered, 10 items (20%) were nearly mastered, and only 19 items (38%) were mastered by the students. Meanwhile, after the MOOC, only 17 items (34%) had been least mastered, and 13 items (26%) as well as 20 items (40%) had been nearly mastered and mastered, respectively. From the statistical data, the researcher inferred that the use of MOOC as a teaching strategy helped Grade 12 students improve their mastery level in MIL. This finding is supported by the increase in the number of mastered items (+2%) and nearly mastered items (+6%). Consequently, there is a decrease in the number of least mastered items (-8%). These findings will serve as the basis for enhancing the learning guide in MOOC
Spin-based quantum gating with semiconductor quantum dots by bichromatic radiation method
A potential scheme is proposed for realizing a two-qubit quantum gate in
semiconductor quantum dots. Information is encoded in the spin degrees of
freedom of one excess conduction electron of each quantum dot. We propose to
use two lasers, radiation two neighboring QDs, and tuned to blue detuning with
respect to the resonant frequencies of individual excitons. The two-qubit phase
gate can be achieved by means of both Pauli-blocking effect and dipole-dipole
coupling between intermediate excitonic states.Comment: Europhysics Letters 66 (2004) 1
Entanglement distribution for a practical quantum-dot-based quantum processor architecture
We propose a quantum dot (QD) architecture for enabling universal quantum information processing. Quantum registers, consisting of arrays of vertically stacked self-assembled semiconductor QDs, are connected by chains of in-plane self-assembled dots. We propose an entanglement distributor, a device for producing and distributing maximally entangled qubits on demand, communicated through in-plane dot chains. This enables the transmission of entanglement to spatially separated register stacks, providing a resource for the realization of a sizeable quantum processor built from coupled register stacks of practical size. Our entanglement distributor could be integrated into many of the present proposals for self-assembled QD-based quantum computation (QC). Our device exploits the properties of simple, relatively short, spin-chains and does not require microcavities. Utilizing the properties of self-assembled QDs, after distribution the entanglement can be mapped into relatively long-lived spin qubits and purified, providing a flexible, distributed, off-line resource. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft
Transvenous nonfluoroscopic pacemaker implantation during pregnancy guided by 3-dimensional electroanatomic mapping
Patients with congenital heart disease are at ongoing risk of developing both bradyarrhythmias and tachyarrhythmias decades after surgical repair. Rarely, arrhythmias can be exacerbated during pregnancy and require emergent intervention. Here, we report unique experience with nonfluoroscopic pacemaker implantation during pregnancy. Ionizing radiation, even in low doses, is associated with an increased risk of malignancy, and a fetus may be at particularly increased risk.1, 2 Over the past 2 decades, the use of fluoroscopy in cardiac ablation procedures has become nearly obsolete with the development of 3-dimensional (3D) electroanatomic mapping software such as CARTO (Biosense-Webster, Diamond Bar, CA) and NavX or EnSite (St. Jude Medical, Inc., St. Paul, MN).3 However, certain procedures, such as device implants, still commonly use fluoroscopy in most instances.2 Fluoroscopy use in patients with congenital heart disease is of utmost concern because of cumulative radiation exposure from multiple lifetime catheterization, radiographic and computed tomography imaging, and electrophysiological procedures
The Relaxation Properties of Myofibrils Are Compromised by Amino Acids that Stabilize α-Tropomyosin
We investigated the functional impact of α-tropomyosin (Tm) substituted with one (D137L) or two (D137L/G126R) stabilizing amino acid substitutions on the mechanical behavior of rabbit psoas skeletal myofibrils by replacing endogenous Tm and troponin (Tn) with recombinant Tm mutants and purified skeletal Tn. Force recordings from myofibrils (15°C) at saturating [Ca(2+)] showed that Tm-stabilizing substitutions did not significantly affect the maximal isometric tension and the rates of force activation (k(ACT)) and redevelopment (k(TR)). However, a clear effect was observed on force relaxation: myofibrils with D137L/G126R or D137L Tm showed prolonged durations of the slow phase of relaxation and decreased rates of the fast phase. Both Tm-stabilizing substitutions strongly decreased the slack sarcomere length (SL) at submaximal activating [Ca(2+)] and increased the steepness of the SL-passive tension relation. These effects were reversed by addition of 10 mM 2,3-butanedione 2-monoxime. Myofibrils also showed an apparent increase in Ca(2+) sensitivity. Measurements of myofibrillar ATPase activity in the absence of Ca(2+) showed a significant increase in the presence of these Tms, indicating that single and double stabilizing substitutions compromise the full inhibition of contraction in the relaxed state. These data can be understood with the three-state (blocked-closed-open) theory of muscle regulation, according to which the mutations increase the contribution of the active open state in the absence of Ca(2+) (M(−)). Force measurements on myofibrils substituted with C-terminal truncated TnI showed similar compromised relaxation effects, indicating the importance of TnI-Tm interactions in maintaining the blocked state. It appears that reducing the flexibility of native Tm coiled-coil structure decreases the optimum interactions of the central part of Tm with the C-terminal region of TnI. This results in a shift away from the blocked state, allowing myosin binding and activity in the absence of Ca(2+). This work provides a basis for understanding the effects of disease-producing mutations in muscle proteins
Hypervelocity Stars from the Andromeda Galaxy
Hypervelocity stars (HVSs) discovered in the Milky Way (MW) halo are thought
to be ejected from near the massive black hole (MBH) at the galactic centre. In
this paper we investigate the spatial and velocity distributions of the HVSs
which are expected to be similarly produced in the Andromeda galaxy (M31). We
consider three different HVS production mechanisms: (i) the disruption of
stellar binaries by the galactocentric MBH; (ii) the ejection of stars by an
in-spiraling intermediate mass black hole; and (iii) the scattering of stars
off a cluster of stellar-mass black holes orbiting around the MBH. While the
first two mechanisms would produce large numbers of HVSs in M31, we show that
the third mechanism would not be effective in M31. We numerically calculate
1.2*10^6 trajectories of HVSs from M31 within a simple model of the Local Group
and hence infer the current distribution of these stars. Gravitational focusing
of the HVSs by the MW and the diffuse Local Group medium leads to high
densities of low mass (~ solar mass) M31 HVSs near the MW. Within the
virialized MW halo, we expect there to be of order 1000 HVSs for the first
mechanism and a few hundred HVSs for the second mechanism; many of these stars
should have distinctively large approach velocities (< -500 km/s). In addition,
we predict ~5 hypervelocity RGB stars within the M31 halo which could be
identified observationally. Future MW astrometric surveys or searches for
distant giants could thus find HVSs from M31.Comment: 14 pages, 6 figures, changed to match version accepted by MNRA
Model studies of dense water overflows in the Faroese Channels Topical Collection on the 5th International Workshop on Modelling the Ocean (IWMO) in Bergen, Norway 17-20 June 2013
The overflow of dense water from the Nordic Seas through the Faroese Channel system was investigated through combined laboratory experiments and numerical simulations using the Massachusetts Institute of Technology General Circulation Model. In the experimental study, a scaled, topographic representation of the Faroe-Shetland Channel, Wyville-Thomson Basin and Ridge and Faroe Bank Channel seabed bathymetry was constructed and mounted in a rotating tank. A series of parametric experiments was conducted using dye-tracing and drogue-tracking techniques to investigate deep-water overflow pathways and circulation patterns within the modelled region. In addition, the structure of the outflowing dense bottom water was investigated through density profiling along three cross-channel transects located in the Wyville-Thomson Basin and the converging, up-sloping approach to the Faroe Bank Channel. Results from the dye-tracing studies demonstrate a range of parametric conditions under which dense water overflow across the Wyville-Thomson Ridge is shown to occur, as defined by the Burger number, a non-dimensional length ratio and a dimensionless dense water volume flux parameter specified at the Faroe-Shetland Channel inlet boundary. Drogue-tracking measurements reveal the complex nature of flow paths and circulations generated in the modelled topography, particularly the development of a large anti-cyclonic gyre in the Wyville-Thompson Basin and up-sloping approach to the Faroe Bank Channel, which diverts the dense water outflow from the Faroese shelf towards the Wyville-Thomson Ridge, potentially promoting dense water spillage across the ridge itself. The presence of this circulation is also indicated by associated undulations in density isopycnals across the Wyville-Thomson Basin. Numerical simulations of parametric test cases for the main outflow pathways and density structure in a similarly-scaled Faroese Channels model domain indicate excellent qualitative agreement with the experimental observations and measurements. In addition, the comparisons show that strong temporal variability in the predicted outflow pathways and circulations have a strong influence in regulating the Faroe Bank Channel and Wyville-Thomson Ridge overflows, as well as in determining the overall response in the Faroese Channels to changes in the Faroe-Shetland Channel inlet boundary conditions. © 2014 Springer-Verlag Berlin Heidelberg
Modeling of liquid flow in surface discontinuities
Polymer composite and metallic materials have found wide application in various industries such as aviation, rocket, car manufacturing, ship manufacturing, etc. Many design elements need permanent quality control. Ensuring high quality and reliability of products is impossible without effective nondestructive testing methods. One of these methods is penetrant testing using penetrating substances based on liquid penetration into defect cavities. In this paper, we propose a model of liquid flow to determine the rates of filling the defect cavities with various materials and, based on this, to choose optimal control modes
- …