| 1. |
- Clark, Andrew G., et al.
(författare)
-
Evolution of genes and genomes on the Drosophila phylogeny
- 2007
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
-
Tidskriftsartikel (refereegranskat)abstract
- Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Gudmundsson, Valur, et al.
(författare)
-
Fully Depleted UTB and Trigate N-Channel MOSFETs Featuring Low-Temperature PtSi Schottky-Barrier Contacts With Dopant Segregation
- 2009
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 30:5, s. 541-543
-
Tidskriftsartikel (refereegranskat)abstract
- Schottky-barrier source/drain (SB-S/D) presents a promising solution to reducing parasitic resistance for device architectures such as fully depleted UTB, trigate, or FinFET. In this letter, a low-temperature process (<= 700 degrees C) with PtSi-based S/D is examined for the fabrication of n-type UTB and trigate FETs on SOI substrate (t(si) = 30 nm). Dopant segregation with As was used to achieve the n-type behavior at implantation doses of 1 (.) 10(15) and 5. 10(15) cm(-2). Similar results were found for UTB devices with both doses, but trigate devices with the larger dose exhibited higher on currents and smaller process variation than their lower dose counterparts.
|
|
| 5. |
- Hållstedt, Julius, et al.
(författare)
-
A robust spacer gate process for deca-nanometer high-frequency MOSFETs
- 2006
-
Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 83:3, s. 434-439
-
Tidskriftsartikel (refereegranskat)abstract
- This paper, presents a robust spacer technology for definition of deca-nanometer gate length MOSFETs. Conformal deposition, selective anisotropic dry-etching and selective removal of sacrificial layers enabled patterning of an oxide hard mask with deca-nanometer lines combined with structures defined with I-line lithography on a wafer. The spacer gate technology produces negligible topographies on the hard mask and no residual particles could be detected on the wafer. The line-width roughness of 40 nm poly-Si gate lines was 4 nm and the conductance of 200 pm long lines exhibited a standard deviation of 6% across a wafer. nMOSFETs with 45 nm gate length exhibited controlled short-channel effects and the average maximum transconductance in saturation was 449 mu S/mu m with a standard deviation of 3.7% across a wafer. The devices exhibited a cut-off frequency above 100 GHz at a drain current of 315 mu A/mu m. The physical and electrical results show that the employed spacer gate technology is robust and can define deca-nanometer nMOSFETs with high yield and good uniformity.
|
|
| 6. |
- Luan, Shi-Lu, 1972-
(författare)
-
Molecular epidemiology of streptococcus agalactiae : mobile elements as genetic markers.
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Streptococcus agalactiae, also designated group B streptococcus (GBS), is a Gram-positive coccus, and it is an important pathogen that causes invasive disease in neonates, pregnant adults, and non-pregnant adults with predisposing conditions. The group II intron GBSi1 is one of the major mobile genetic elements identified in S. agalactiae. The aim of this thesis was to characterize the GBSi1 distribution pattern, the population structure, and the influence of serotype- and clone-specific properties on the invasive capacity among clinical invasive and non-invasive isolates of S. agalactiae.Two additional copies of GBSi1 were identified at sites different from the primarily identified scpB-lmb locus. The distribution of GBSi1 was uneven among different serotypes. Three intron copies were only found in isolates of serotype III, and these targeted all the three identified gene loci. In contrast, a single copy of GBSi1 was found in isolates of serotype II and V and only located at the scpB-lmb locus. Furthermore, at the 5′ flanking region of the scpB-lmb gene locus, a novel 2.1 kb DNA fragment with plasmid features was identified only in intron carrying isolates. This may suggest that GBSi1 once was brought into the S. agalactiae genome by an integrated plasmid.Multilocus sequence typing was used to characterize totally 314 invasive and non-invasive S. agalactiae isolates collected in Northern and Western Sweden from the years 1988 to 2004. Five major genetic lineages (clonal complexes) were identified among both invasive and non-invasive isolates, including serotype Ia, Ib, and II to V, indicating a clonal population structure of S. agalactiae isolates. A number of genetically highly related isolates were found to express different capsular types, suggesting that capsule switching occurs rather frequently between isolates. Furthermore, non-invasive isolates belonging to the same clonal complexes displayed more heterogeneity in capsule expression as well as in the distribution patterns of mobile genetic elements than invasive isolates. This indicates that less variability is allowed in a highly selective environment such as the blood. All major clonal complexes and serotypes caused invasive disease, although their ability to do so varied greatly. CC17 was significantly associated with neonatal invasive disease; whereas CC19 was equally common among isolates from adult and neonatal disease, despite that both CC17 and CC19 expressed capsular type III. This striking difference seen between CC17 and CC19 suggests that clonal complex associated properties, in addition to capsular type, play important roles in the virulence of S. agalactiae. CC1, a new emerging clone since early 1990s, has caused substantial amount of disease among adults. In addition, mutually exclusive distribution of mobile elements GBSi1 and IS1548 was seen, and they were shown to constitute genetic markers for serotype III CC17 and CC19 isolates, respectively.
|
|
| 7. |
- Luan, Shi-Lu, et al.
(författare)
-
Multilocus sequence typing of Swedish invasive group B streptococcus isolates indicates a neonatally associated genetic lineage and capsule switching.
- 2005
-
Ingår i: Journal of clinical microbiology. - 0095-1137 .- 1098-660X. ; 43:8, s. 3727-33
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus agalactiae, also designated group B streptococcus (GBS), is an important pathogen in neonates, pregnant women, and nonpregnant adults with predisposing conditions. We used multilocus sequence typing (MLST) to characterize 158 GBS isolates that were associated with neonatal and adult invasive disease and that were collected in northern and western Sweden from 1988 to 1997. Five major genetic lineages (sequence type [ST] 19, ST-17, ST-1, ST-23, and ST-9 complexes) were identified among the isolates, including serotype Ia, Ib, and II to V isolates, indicating a highly clonal population structure among invasive GBS isolates. A number of STs were found to contain isolates of different serotypes, which indicates that capsule switching occurred rather frequently. Two distantly related genetic lineages were identified among isolates of serotype III, namely, clonal complex 19 (CC19), and CC17. CC19 was equally common among isolates from adult and neonatal disease (accounting for 10.3% of GBS isolates from adult disease and 18.7% from neonatal disease), whereas CC17 significantly appeared to be associated with neonatal invasive disease (isolated from 21.9% of neonatal isolates but only 2.6% of adult isolates). The distribution of the mobile elements GBSi1 and IS1548 reveals that they can act as genetic markers for lineages CC17 and CC19, respectively.
|
|
| 8. |
- Qiu, Zhijun, et al.
(författare)
-
Silicide as diffusion source for dopant segregation in 70-nm MOSFETs with PtSi Schottky-barrier source/drain on ultrathin-body SOI
- 2008
-
Ingår i: ULIS 2008. - NEW YORK : IEEE. ; , s. 23-26
-
Konferensbidrag (refereegranskat)abstract
- In this paper, dopant segregation (DS) method is adopted to enhance device performance of PtSi-based Schottky-barrier source/drain MOSFETs (SB-MOSFETs) fabricated on ultrathin silicon-on-insulator. The DS formation is realized by means of Silicide As Diffusion Source. Without DS treatment, the devices are typically p-type, but with a rather large electron branch at positive gate bias. Dopant segregation with As is found to turn the devices to well-performing n-MOSFETs, and DS with B to greatly enhance the hole conduction in the p-MOSFETs. A large threshold voltage (V-t) shift is however observed in the p-MOSFET due to B lateral spread caused during the drive-in process for the DS formation. By reducing the drive-in temperature, this problem is partially addressed with a smaller V-t shift and a much better control of short channel effect.
|
|
| 9. |
- Seger, Johan, et al.
(författare)
-
Lateral encroachment of Ni-silicides in the source/drain regions on ultrathin silicon-on-insulator
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:25
-
Tidskriftsartikel (refereegranskat)abstract
- Lateral growth of Ni silicide towards the channel region of metal-oxide-semiconductor transistors (MOSFETs) fabricated on ultrathin silicon-on-insulator (SOI) is characterized using SOI wafers with a 20-nm-thick surface Si layer. With a 10-nm-thick Ni film for silicide formation, p-channel MOSFETs displaying ordinary device characteristics with silicided p(+) source/drain regions were demonstrated. No lateral growth of NiSix under gate isolation spacers was found according to electron microscopy. When the Ni film was 20 nm thick, Schottky contact source/drain MOSFETs showing typical ambipolar characteristics were obtained. A severe lateral encroachment of NiSix into the channel region leading to an increased gate leakage was revealed, while no detectable voiding at the silicide front towards the Si channel was observed.
|
|
| 10. |
|
|
