745 research outputs found
A Comparison of Students\u27 Anxiety Levels While Taking Computer Versus Paper and Pencil Timed Math Tests
The purpose of this research is to compare and contrast the anxiety levels of students before and after taking the computerized timed math test with the levels before and after taking the paper-and-pencil timed math test. Two second-grade classes were used in this research with each student taking each test once. The computer test, found at www .saxonpublishers.com/activities/basic fact_ sheets/, consisted of 50 addition questions to be completed in 30 seconds, and the paper-and-pencil version, adapted by the researcher from a Saxon created test, consisted of 100 addition questions to be completed in 60 seconds. The students\u27 blood pressures and pulses were taken while they were at rest before the tests, right before they were told to begin the test, and right after the test was over. An elevation from the at rest readings to the beginning readings indicates increase in anxiety, as does an increase from the at rest readings to the ending readings. The differences in blood pressures and pulses of both tests were compared for each student with the least amount of change indicating less anxiety was experienced while taking that test. The scores of the two tests were also compared with the better score indicating less anxiety experienced while taking that test. All the students responded to a survey and several randomly chosen students were interviewed about their experiences and feelings toward the tests and research process
The bondage number of graphs on topological surfaces and Teschner's conjecture
The bondage number of a graph is the smallest number of its edges whose
removal results in a graph having a larger domination number. We provide
constant upper bounds for the bondage number of graphs on topological surfaces,
improve upper bounds for the bondage number in terms of the maximum vertex
degree and the orientable and non-orientable genera of the graph, and show
tight lower bounds for the number of vertices of graphs 2-cell embeddable on
topological surfaces of a given genus. Also, we provide stronger upper bounds
for graphs with no triangles and graphs with the number of vertices larger than
a certain threshold in terms of the graph genera. This settles Teschner's
Conjecture in positive for almost all graphs.Comment: 21 pages; Original version from January 201
Inhibition of PI3K-Akt Signaling Blocks Exercise-Mediated Enhancement of Adult Neurogenesis and Synaptic Plasticity in the Dentate Gyrus
Physical exercise has been shown to increase adult neurogenesis in the dentate gyrus and enhances synaptic plasticity. The antiapoptotic kinase, Akt has also been shown to be phosphorylated following voluntary exercise; however, it remains unknown whether the PI3K-Akt signaling pathway is involved in exercise-induced neurogenesis and the associated facilitation of synaptic plasticity in the dentate gyrus.To gain insight into the potential role of this signaling pathway in exercise-induced neurogenesis and LTP in the dentate gyrus rats were infused with the PI3K inhibitor, LY294002 or vehicle control solution (icv) via osmotic minipumps and exercised in a running wheel for 10 days. Newborn cells in the dentate gyrus were date-labelled with BrdU on the last 3 days of exercise. Then, they were either returned to the home cage for 2 weeks to assess exercise-induced LTP and neurogenesis in the dentate gyrus, or were killed on the last day of exercise to assess proliferation and activation of the PI3K-Akt cascade using western blotting.Exercise increases cell proliferation and promotes survival of adult-born neurons in the dentate gyrus. Immediately after exercise, we found that Akt and three downstream targets, BAD, GSK3beta and FOXO1 were activated. LY294002 blocked exercise-induced phosphorylation of Akt and downstream target proteins. This had no effect on exercise-induced cell proliferation, but it abolished most of the beneficial effect of exercise on the survival of newly generated dentate gyrus neurons and prevented exercise-induced increase in dentate gyrus LTP. These results suggest that activation of the PI3 kinase-Akt signaling pathway plays a significant role via an antiapoptotic function in promoting survival of newly formed granule cells generated during exercise and the associated increase in synaptic plasticity in the dentate gyrus
Irreducible triangulations of surfaces with boundary
A triangulation of a surface is irreducible if no edge can be contracted to
produce a triangulation of the same surface. In this paper, we investigate
irreducible triangulations of surfaces with boundary. We prove that the number
of vertices of an irreducible triangulation of a (possibly non-orientable)
surface of genus g>=0 with b>=0 boundaries is O(g+b). So far, the result was
known only for surfaces without boundary (b=0). While our technique yields a
worse constant in the O(.) notation, the present proof is elementary, and
simpler than the previous ones in the case of surfaces without boundary
Hamiltonian submanifolds of regular polytopes
We investigate polyhedral -manifolds as subcomplexes of the boundary
complex of a regular polytope. We call such a subcomplex {\it -Hamiltonian}
if it contains the full -skeleton of the polytope. Since the case of the
cube is well known and since the case of a simplex was also previously studied
(these are so-called {\it super-neighborly triangulations}) we focus on the
case of the cross polytope and the sporadic regular 4-polytopes. By our results
the existence of 1-Hamiltonian surfaces is now decided for all regular
polytopes.
Furthermore we investigate 2-Hamiltonian 4-manifolds in the -dimensional
cross polytope. These are the "regular cases" satisfying equality in Sparla's
inequality. In particular, we present a new example with 16 vertices which is
highly symmetric with an automorphism group of order 128. Topologically it is
homeomorphic to a connected sum of 7 copies of . By this
example all regular cases of vertices with or, equivalently, all
cases of regular -polytopes with are now decided.Comment: 26 pages, 4 figure
The maximum number of cliques in a graph embedded in a surface
This paper studies the following question: Given a surface and an
integer , what is the maximum number of cliques in an -vertex graph
embeddable in ? We characterise the extremal graphs for this question,
and prove that the answer is between and , where is the maximum integer such that the
complete graph embeds in . For the surfaces ,
, , , ,
and we establish an exact answer
Application de la méthode des transformateurs saturés à la mesure et régulation du champ magnétique d'un spectromètre β à double focalisation π √2 avec noyau de fer
On décrit un nouveau magnétomètre pour mesurer les champs magnétiques constants ou lentement variables dans l'intervalle de variation entre 10 -4 et 3 x 102 Oe. La précision relative est supérieure à 2,5 X 10-5 entre 7 et 300 Oe. Le champ magnétique d'un spectromètre β à double focalisation π √2 du type Siegbahn-Svartholm est stabilisé par un servomécanisme. On utilise comme signal d'erreur la différence entre une tension proportionnelle au champ d'induction magnétique et une tension de référence
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