13,281 research outputs found
Is There a General Motor Program for Right Versus Left Hand Throwing in Children?
The purpose of this study was to determine if a general motor program controlled some or all aspects of overhand throwing. Using a 12 camera Vicon motion analysis system to record data from body markers, a group of 30 Australian Aboriginal children 6-10 years of age threw with maximal effort into a large target area. Data were reduced and analysed for numerous variables and correlations were calculated between dominant and non-dominant side variables that were deemed reliable. Results indicated that five variables showed significant dominant to non-dominant correlations. However, only two of the five were entered into both multiple regressions to predict horizontal ball velocity for the dominant vs. non-dominant sides. The variables entered suggested that more gross aspects of the movement (stride distance and pelvis flexion) were both correlated from dominant to non-dominant sides and predicted horizontal ball velocity. Thus, the general motor program does not appear to control the more complex and coordinated parts of the throwing motion
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Additive Manufacturing (AM) and Nanotechnology: Promises and Challenges
The narrow choice of materials used in Additive Manufacturing (AM) remains a key
limitation to more advanced systems. Nanomaterials offer the potential to advance AM materials
through modification of their fundamental material properties. In this paper, the authors provide
a review of available published literature in which nanostructures are incorporated into AM
printing media as an attempt to improve the properties of the final printed part. Specifically, we
review the research in which metal, ceramic, and carbon nanomaterials have been incorporated
into AM technologies such as stereolithography, laser sintering, fused filament fabrication, and
three-dimensional printing. The purpose of this article is to summarize the research done to date,
to highlight successes in the field, and to identify opportunities that the union of AM and
nanotechnology could bring to science and technology.Mechanical Engineerin
The NF-κB subunit c-Rel regulates Bach2 tumour suppressor expression in B-cell lymphoma
The REL gene, encoding the NF-κB subunit c-Rel, is frequently amplified in B-cell lymphoma and functions as a tumour-promoting transcription factor. Here we report the surprising result that c-rel–/– mice display significantly earlier lymphomagenesis in the c-Myc driven, Eμ-Myc model of B-cell lymphoma. c-Rel loss also led to earlier onset of disease in a separate TCL1-Tg-driven lymphoma model. Tumour reimplantation experiments indicated that this is an effect intrinsic to the Eμ-Myc lymphoma cells but, counterintuitively, c-rel–/– Eμ-Myc lymphoma cells were more sensitive to apoptotic stimuli. To learn more about why loss of c-Rel led to earlier onset of disease, microarray gene expression analysis was performed on B cells from 4-week-old, wild-type and c-rel–/– Eμ-Myc mice. Extensive changes in gene expression were not seen at this age, but among those transcripts significantly downregulated by the loss of c-Rel was the B-cell tumour suppressor BTB and CNC homology 2 (Bach2). Quantitative PCR and western blot analysis confirmed loss of Bach2 in c-Rel mutant Eμ-Myc tumours at both 4 weeks and the terminal stages of disease. Moreover, Bach2 expression was also downregulated in c-rel–/– TCL1-Tg mice and RelA Thr505Ala mutant Eμ-Myc mice. Analysis of wild-type Eμ-Myc mice demonstrated that the population expressing low levels of Bach2 exhibited the earlier onset of lymphoma seen in c-rel–/– mice. Confirming the relevance of these findings to human disease, analysis of chromatin immunoprecipitation sequencing data revealed that Bach2 is a c-Rel and NF-κB target gene in transformed human B cells, whereas treatment of Burkitt's lymphoma cells with inhibitors of the NF-κB/IκB kinase pathway or deletion of c-Rel or RelA resulted in loss of Bach2 expression. These data reveal a surprising tumour suppressor role for c-Rel in lymphoma development explained by regulation of Bach2 expression, underlining the context-dependent complexity of NF-κB signalling in cancer
1863-03-02 Sergeant Thomas B. Campbell of Company E solicits a position as 2nd Lieutenant from George A. Starr
https://digitalmaine.com/cw_me_4th_regiment_corr/1348/thumbnail.jp
Low State, Phase-Resolved IR Spectroscopy of VV Puppis
We present phase-resolved low resolution and higher resolution -band
spectroscopy of the polar VV Pup. All observations were obtained when VV Pup
was in a low accretion state having a K magnitude near 15. The low resolution
observations reveal cyclotron emission in the band during some phases,
consistent with an origin near the active 30.5 MG pole on the white dwarf. The
secondary in VV Pup appears to be a normal M7V star and we find that the
and band fluxes are entirely due to this star at all orbital phases during
the low accretion state. We use our higher resolution Keck spectroscopy to
produce the first -band radial velocity curve for VV Pup. Our orbital
solution yields =414 km sec and leads to mass estimates of
M=0.730.05 M and M=0.100.02 M. We find
that the mass accretion rates during the normal low states of the polars VV
Pup, EF Eri, and EQ Cet are near 10 M yr. The fact
that \.M is not zero in low state polars indicates active secondary stars in
these binary systems, including the sub-stellar donor star present in EF Eri.Comment: Accepted in Astronomical Journal 5 figure
Energy-Momentum Tensor for the Electromagnetic Field in a Dielectric
The total momentum of a thermodynamically closed system is unique, as is the
total energy. Nevertheless, there is continuing confusion concerning the
correct form of the momentum and the energy-momentum tensor for an
electromagnetic field interacting with a linear dielectric medium. Here we
investigate the energy and momentum in a closed system composed of a
propagating electromagnetic field and a negligibly reflecting dielectric. The
Gordon momentum is easily identified as the total momentum by the fact that it
is, by virtue of being invariant in time, conserved. We construct continuity
equations for the energy and the Gordon momentum and use the continuity
equations to construct an array that has the properties of a traceless,
diagonally symmetric energy-momentum tensor. Then the century-old
Abraham-Minkowski momentum controversy can be viewed as a consequence of
attempting to construct an energy-momentum tensor from continuity equations
that contain densities that correspond to nonconserved quantities.Comment: added publication informatio
Damage spreading in random field systems
We investigate how a quenched random field influences the damage spreading
transition in kinetic Ising models. To this end we generalize a recent master
equation approach and derive an effective field theory for damage spreading in
random field systems. This theory is applied to the Glauber Ising model with a
bimodal random field distribution. We find that the random field influences the
spreading transition by two different mechanisms with opposite effects. First,
the random field favors the same particular direction of the spin variable at
each site in both systems which reduces the damage. Second, the random field
suppresses the magnetization which, in turn, tends to increase the damage. The
competition between these two effects leads to a rich behavior.Comment: 4 pages RevTeX, 3 eps figure
Resistance Status of House Flies (Diptera: Muscidae) from Southeastern Nebraska Beef Cattle Feedlots to Selected Insecticides
The status of resistance to three insecticides (permethrin, stirofos, and methoxychlor), relative to a laboratory-susceptible colony, was evaluated in Þeld populations of house flies, Musca domestica L., collected from two beef cattle feedlots in southeastern Nebraska. Topical application and residual exposure to treated glass surfaces were suitable methods for determining the resistance status of house flies to permethrin, stirofos, or methoxychlor. However, in most cases, residual exposure was more sensitive in resistance detection (i.e., higher resistance ratios). The field populations tested were moderately resistant to permethrin (RR = 4.9-fold and RR = 7.3-fold, for topical application and residual exposure, respectively) and extremely resistant to stirofos and methoxychlor (not accurately quantifiable be cause of low mortality at the highest possible concentrations or doses). Probable explanations for the resistance status of these house fly populations and implications for global feedlot fly management are discussed
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