| 1. |
- Oberg, Johanna, et al.
(författare)
-
Age related changes in brain metabolites observed by 1H MRS in APP/PS1 mice
- 2008
-
Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 29:9, s. 1423-1433
-
Tidskriftsartikel (refereegranskat)abstract
- Translational biomarkers in Alzheimer's disease based on non-invasive in vivo methods are highly warranted. (1)H magnetic resonance spectroscopy (MRS) is non-invasive and applicable in vivo in both humans and experimental animals. In vivo(1)H MRS and 3D MRI were performed on brains of double transgenic (tg) mice expressing a double mutant human beta-amyloid precursor protein APP(K670N,M671L) and human mutated presenilin gene PS1M146L, and wild-type (wt) littermates at 2.5, 6.5 and 9 months of age using a 9.4T magnet. For quantification, LCModel was used, and the data were analyzed using multivariate data analysis (MVDA). MVDA evidenced a significant separation, which became more pronounced with age, between tg and wt mice at all time points. While myo-inositol and guanidoacetate were important for group separation in young mice, N-acetylaspartate, glutamate and macrolipids were important for separation of aged tg and wt mice. Volume segmentation revealed that brain and hippocampus were readily smaller in tg as compared to wt mice at the age of 2.5 months. Amyloid plaques were seen in 6.5 and 9 months, but not in 2.5 months old animals. In conclusion, differences in brain metabolites could be accurately depicted in tg and wt mice in vivo by combining MRS with MVDA. First differences in metabolite content were readily seen at 2.5 months, when volume defects in tg mice were present, but no amyloid plaques.
|
|
| 2. |
- Vedmar, Lars, et al.
(författare)
-
A parametric Analysis of the Undeformed Chip Geometry in Gear Hobbing
- 2009
-
Ingår i: Journal of Manufacturing Science and Engineering. - : ASME International. - 1528-8935 .- 1087-1357. ; 131:December 2009, s. 1-061003
-
Forskningsöversikt (refereegranskat)abstract
- Hobbing is a common manufacturing method when producing helical, involute gears. In order to increase tool life and surface finish, an accurate method to determine chip geometry is needed. Although this accurateness may involve numeric solutions, the geometric description must, as far as possible, be analytic and give a description of the continuously changing chip geometry. In this report, the cutting edges of the tool are mathematically described using parametric and analytically differentiable functions. This gives the possibility to determine the geometry of the three-dimensional surface on the blank each cutting edge will cut, with numeric approximations kept to a minimum. By comparing successively cut surfaces, the chip geometry is determined using the tool and process parameters. The mathematical description gives the possibility to calculate the required characteristic properties of the chips. These are needed for increasing the tool life in order to develop more efficient tools and processes. An example is given in which characteristics, as the maximum chip thickness, the chip cross-section area, and the mean chip thickness are calculated. The reported theory describes in detail how the chip geometry is determined.
|
|
