305 research outputs found
Mixing Problem Based Learning And Conventional Teaching Methods In An Analog Electronics Course
This study, undertaken at the Walter Sisulu University of Technology (WSU) in South Africa, describes how problem-based learning (PBL) affects the first year âanalog electronics courseâ, when PBL and the lecturing mode is compared. Problems were designed to match real-life situations. Data between the experimental group and the control group that related to attitudinal effect; the amount of reflection and learning outcome effects, were compared. A strong correlation was found between the studentsâ attitudes and project marks for those who used the problem-based learning method. It was found that students who followed the PBL method learned to do research, learned better how to work in groups and developed greater confidence. Also what they learned was more of a practical value and they had more positive attitudes and reflected more, but there were no significant improvements in their learning. This research is in response to the real need to address gaps between employer expectations and higher education outcomes in South Africa.
A Search for Non-triggered Gamma Ray Bursts in the BATSE Data Base
We describe a search of archival data from the Burst and Transient Source
Experiment (BATSE). The purpose of the search is to find astronomically
interesting transients that did not activate the burst detection (or
``trigger'') system onboard the spacecraft. Our search is sensitive to events
with peak fluxes (on the 1.024 s time scale) that are lower by a factor of 2
than can be detected with the onboard burst trigger. In a search of 345 days of
archival data, we detected 91 events in the 50--300 keV range that resemble
classical gamma ray bursts but that did not activate the onboard burst trigger.
We also detected 110 low-energy (25--50 keV) events of unknown origins which
may include activity from SGR 1806-20 and bursts and flares from X-ray
binaries. This paper gives the occurrence times, estimated source directions,
durations, peak fluxes, and fluences for the 91 gamma ray burst candidates. The
direction and intensity distributions of these bursts imply that the biases
inherent in the onboard trigger mechanism have not significantly affected the
completeness of the published BATSE gamma ray burst catalogs.Comment: Fixed incorrect values of and added erratum sectio
Limits on the cosmological abundance of supermassive compact objects from a millilensing search in gamma-ray burst data
A new search for the gravitational lens effects of a significant cosmological
density of supermassive compact objects (SCOs) on gamma-ray bursts has yielded
a null result. We inspected the timing data of 774 BATSE-triggered GRBs for
evidence of millilensing: repeated peaks similar in light-curve shape and
spectra. Our null detection leads us to conclude that, in all candidate
universes simulated, is favored for , while in some universes and mass ranges the density
limits are as much as 10 times lower. Therefore, a cosmologically significant
population of SCOs near globular cluster mass neither came out of the
primordial universe, nor condensed at recombination.Comment: 14 pages including 3 figures, appeared 2001 January 2
Continuous sensing and quantification of body motion in infants:A systematic review
Abnormal body motion in infants may be associated with neurodevelopmental delay or critical illness. In contrast to continuous patient monitoring of the basic vitals, the body motion of infants is only determined by discrete periodic clinical observations of caregivers, leaving the infants unattended for observation for a longer time. One step to fill this gap is to introduce and compare different sensing technologies that are suitable for continuous infant body motion quantification. Therefore, we conducted this systematic review for infant body motion quantification based on the PRISMA method (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). In this systematic review, we introduce and compare several sensing technologies with motion quantification in different clinical applications. We discuss the pros and cons of each sensing technology for motion quantification. Additionally, we highlight the clinical value and prospects of infant motion monitoring. Finally, we provide suggestions with specific needs in clinical practice, which can be referred by clinical users for their implementation. Our findings suggest that motion quantification can improve the performance of vital sign monitoring, and can provide clinical value to the diagnosis of complications in infants.</p
On the nature of XTE J0421+560/CI Cam
We present the results of the analysis of RXTE, BATSE and optical/infrared
data of the 1998 outburst of the X-ray transient system XTE J0421+560 (CI Cam).
The X-ray outburst shows a very fast decay (initial e-folding time ~0.5 days,
slowing down to ~2.3 days). The X-ray spectrum in the 2-25 keV band is complex,
softening considerably during decay and with strongly variable intrinsic
absorption. A strong iron emission line is observed. No fast time variability
is detected (<0.5 % rms in the 1-4096 Hz band at the outburst peak). The
analysis of the optical/IR data suggests that the secondary is a B[e] star
surrounded by cool dust and places the system at a distance of >~ 2 kpc. At
this distance the peak 2-25 keV luminosity is ~4 x 10^37 erg/s. We compare the
properties of this peculiar system with those of the Be/NS LMC transient A
0538-66 and suggest that CI Cam is of similar nature. The presence of strong
radio emission during outburst indicates that the compact object is likely to
be a black hole or a weakly magnetized neutron star.Comment: Accepted for publication on The Astrophysical Journal, July 199
On the Association of -Ray Bursts with Supernovae
The recent discovery of a supernova (SN 1998bw) seemingly associated with GRB~980425 adds a new twist to the decades-old debate over the origin of gamma-ray bursts. To investigate the possibility that some (or all) bursts are associated with supernovae, we performed a systematic search for temporal/angular correlations using catalogs of BATSE and BATSE/{\it Ulysses} burst locations. We find no associations with any of the precise BATSE/ Ulysses locations, which allows us to conclude that the fraction of high-fluence gamma-ray bursts associated with known supernovae is small (0.2%). For the more numerous weaker bursts, the corresponding limiting fraction of 2.5% is far less constraining due to the imprecise locations of these events. This fraction (2.5%) of bursts corresponds to 30% of the recent supernovae used as a comparison data set. Thus, although we find no significant evidence to support a burst/supernova association, the possibility cannot be excluded for weak bursts
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