2,284 research outputs found
Bisimple monogenic orthodox semigroups
We give a complete description of the structure of all bisimple orthodox
semigroups generated by two mutually inverse elements
Examining Self-Regulation Of Learning Among Community College Students In Developmental Mathematics Courses
The ability to self-regulate one’s learning is crucial to the success of all college students, but is particularly important to those who are considered to be underprepared; it puts students on a path towards successful course completion, subsequent course enrollment, and eventual graduation from a postsecondary institution. Those enrolled in remedial coursework are a large portion of students labeled as underprepared. Remedial education is a contentious topic in higher education. Thus, it is critical to investigate the use of classroom strategies to foster a self-regulated environment to support student success in these early classes and move onto the classes needed for their majors. The purpose of this study was to examine if multiple direct instruction, self-regulation interventions had an effect on students’ reported self-regulatory strategy use, students’ reported mathematics self-efficacy, and successful course completion in a developmental mathematics course.
Using Hunter’s (1982) method of direct instruction, a set of interventions focused on self-regulatory skill improvement were embedded into two sections of a community college developmental mathematics course. Interventions addressed time management, exam preparation, exam error analysis, and recognition of maladaptive behaviors. To gauge the impact of the interventions, a web-based survey regarding self-regulatory tendencies and mathematics self-efficacy was distributed twice during the course. Students in the intervention sections as well as students in two other sections not receiving the intervention, which served as a control, completed the survey. Ultimately, 12 participants from each group were included in the main analyses to determine if there was a statistical difference between those who received the set of interventions and those who did not.
Results indicated no statistical differences between the control and intervention groups in regards to metacognitive self-regulation, mastery self-talk, regulating time and study environment, avoiding needed help, and mathematics self-efficacy. There was an interaction between the groups regarding effort regulation. There was a decrease in effort regulation over time in the intervention group, but no change in the control group. There was also a between-groups difference in seeking needed help, as the intervention group had higher mean values both prior to and after the set of interventions
Device for in-situ cleaving of hard crystals
Cleaving crystals in a vacuum chamber is a simple method for obtaining
atomically flat and clean surfaces for materials that have a preferential
cleaving plane. Most in-situ cleavers use parallel cutting edges that are
applied from two sides on the sample. We found in ambient experiments that
diagonal cutting pliers, where the cleavage force is introduced in a single
point instead of a line work very well also for hard materials. Here, we
incorporate the diagonal cutting plier principle in a design compatible with
ultra-high vacuum requirements. We show optical microscopy (mm scale) and
atomic force microscopy (atomic scale) images of NiO(001) surfaces cleaved with
this device.Comment: 7 pages, 3 figures Submitted to Review of Scientific Instruments
(2005
Looking for Design in Materials Design
Despite great advances in computation, materials design is still science
fiction. The construction of structure-property relations on the quantum scale
will turn computational empiricism into true design.Comment: 3 pages, 1 figur
Assessing Spontaneous Combustion Instability with Nonlinear Time Series Analysis
Considerable interest lies in the ability to characterize the onset of spontaneous instabilities within liquid propellant rocket engine (LPRE) combustion devices. Linear techniques, such as fast Fourier transforms, various correlation parameters, and critical damping parameters, have been used at great length for over fifty years. Recently, nonlinear time series methods have been applied to deduce information pertaining to instability incipiency hidden in seemingly stochastic combustion noise. A technique commonly used in biological sciences known as the Multifractal Detrended Fluctuation Analysis has been extended to the combustion dynamics field, and is introduced here as a data analysis approach complementary to linear ones. Advancing, a modified technique is leveraged to extract artifacts of impending combustion instability that present themselves a priori growth to limit cycle amplitudes. Analysis is demonstrated on data from J-2X gas generator testing during which a distinct spontaneous instability was observed. Comparisons are made to previous work wherein the data were characterized using linear approaches. Verification of the technique is performed by examining idealized signals and comparing two separate, independently developed tools
A multiphase seismic investigation of the shallow subduction zone, southern North Island, New Zealand
The shallow structure of the Hikurangi margin, in particular the interface between the Australian Plate and the subducting Pacific Plate, is investigated using the traveltimes of direct and converted seismic phases from local earthquakes. Mode conversions take place as upgoing energy from earthquakes in the subducted slab crosses the plate interface. These PS and SP converted arrivals are observed as intermediate phases between the direct P and S waves. They place an additional constraint on the depth of
the interface and enable the topography of the subducted plate to be mapped across the region. 301 suitable earthquakes were recorded by the Leeds (Tararua) broad-band seismic array, a temporary line of three-component short-period stations, and the permanent stations of the New Zealand national network. This provided coverage across the land area of southern North Island, New Zealand, at a total of 17 stations. Rays are traced
through a structure parametrized using layered B-splines and the traveltime residuals inverted, simultaneously, for hypocentre relocation, interface depth and seismic velocity. The results are consistent with sediment in the northeast of the study region and gentle topography on the subducting plate. This study and recent tectonic reconstructions of the southwest Pacific suggest that the subducting plate consists of captured, oceanic
crust. The anomalous nature of this crust partly accounts for the unusual features of the Hikurangi margin, e.g. the shallow trench, in comparison with the subducting margin
further north
Characterization of Pump-Induced Acoustics in Space Launch System Main Propulsion System Liquid Hydrogen Feedline Using Airflow Test Data
High intensity acoustic edgetones located upstream of the RS-25 Low Pressure Fuel Turbo Pump (LPFTP) were previously observed during Space Launch System (STS) airflow testing of a model Main Propulsion System (MPS) liquid hydrogen (LH2) feedline mated to a modified LPFTP. MPS hardware has been adapted to mitigate the problematic edgetones as part of the Space Launch System (SLS) program. A follow-on airflow test campaign has subjected the adapted hardware to tests mimicking STS-era airflow conditions, and this manuscript describes acoustic environment identification and characterization born from the latest test results. Fluid dynamics responsible for driving discrete excitations were well reproduced using legacy hardware. The modified design was found insensitive to high intensity edgetone-like discretes over the bandwidth of interest to SLS MPS unsteady environments. Rather, the natural acoustics of the test article were observed to respond in a narrowband-random/mixed discrete manner to broadband noise thought generated by the flow field. The intensity of these responses were several orders of magnitude reduced from those driven by edgetones
Revealing common artifacts due to ferromagnetic inclusions in highly-oriented pyrolytic graphite
We report on an extensive investigation to figure out the origin of
room-temperature ferromagnetism that is commonly observed by SQUID magnetometry
in highly-oriented pyrolytic graphite (HOPG). Electron backscattering and X-ray
microanalysis revealed the presence of micron-size magnetic clusters
(predominantly Fe) that are rare and would be difficult to detect without
careful search in a scanning electron microscope in the backscattering mode.
The clusters pin to crystal boundaries and their quantities match the amplitude
of typical ferromagnetic signals. No ferromagnetic response is detected in
samples where we could not find such magnetic inclusions. Our experiments show
that the frequently reported ferromagnetism in pristine HOPG is most likely to
originate from contamination with Fe-rich inclusions introduced presumably
during crystal growth.Comment: 8 pages, 7 figure
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