| 1. |
- Stacey, Simon N, et al.
(författare)
-
A germline variant in the TP53 polyadenylation signal confers cancer susceptibility.
- 2011
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 43:11, s. 1098-103
-
Tidskriftsartikel (refereegranskat)abstract
- To identify new risk variants for cutaneous basal cell carcinoma, we performed a genome-wide association study of 16 million SNPs identified through whole-genome sequencing of 457 Icelanders. We imputed genotypes for 41,675 Illumina SNP chip-typed Icelanders and their relatives. In the discovery phase, the strongest signal came from rs78378222[C] (odds ratio (OR) = 2.36, P = 5.2 × 10(-17)), which has a frequency of 0.0192 in the Icelandic population. We then confirmed this association in non-Icelandic samples (OR = 1.75, P = 0.0060; overall OR = 2.16, P = 2.2 × 10(-20)). rs78378222 is in the 3' untranslated region of TP53 and changes the AATAAA polyadenylation signal to AATACA, resulting in impaired 3'-end processing of TP53 mRNA. Investigation of other tumor types identified associations of this SNP with prostate cancer (OR = 1.44, P = 2.4 × 10(-6)), glioma (OR = 2.35, P = 1.0 × 10(-5)) and colorectal adenoma (OR = 1.39, P = 1.6 × 10(-4)). However, we observed no effect for breast cancer, a common Li-Fraumeni syndrome tumor (OR = 1.06, P = 0.57, 95% confidence interval 0.88-1.27).
|
|
| 2. |
- Agnarsson, Björn, 1977, et al.
(författare)
-
Rutile TiO 2 thin films grown by reactive high power impulse magnetron sputtering
- 2013
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 545, s. 445-450
-
Tidskriftsartikel (refereegranskat)abstract
- Thin TiO 2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 C.Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing inc idence X-ray diffractometry and spectroscopic ellipsometry.Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO 2 , even prior to post-annealing.The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 C.In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300-700 C.Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7-2.85 at 500 nm.The results show that thin, rutile TiO 2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing.Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts.© 2013 Elsevier B.V.All rights reserved.
|
|
| 3. |
- Bokhorst, Stef Frederik, et al.
(författare)
-
Variable temperature effects of Open Top Chambers at polar and alpine sites explained by irradiance and snow depth
- 2013
-
Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 19:1, s. 64-74
-
Forskningsöversikt (refereegranskat)abstract
- Environmental manipulation studies are integral to determining biological consequences of climate warming. Open Top Chambers (OTCs) have been widely used to assess summer warming effects on terrestrial biota, with their effects during other seasons normally being given less attention even though chambers are often deployed year-round. In addition, their effects on temperature extremes and freeze-thaw events are poorly documented. To provide robust documentation of the microclimatic influences of OTCs throughout the year, we analysed temperature data from 20 studies distributed across polar and alpine regions. The effects of OTCs on mean temperature showed a large range (-0.9 to 2.1 degrees C) throughout the year, but did not differ significantly between studies. Increases in mean monthly and diurnal temperature were strongly related (R-2 = 0.70) with irradiance, indicating that PAR can be used to predict the mean warming effect of OTCs. Deeper snow trapped in OTCs also induced higher temperatures at soil/vegetation level. OTC-induced changes in the frequency of freeze-thaw events included an increase in autumn and decreases in spring and summer. Frequency of high-temperature events in OTCs increased in spring, summer and autumn compared with non-manipulated control plots. Frequency of low-temperature events was reduced by deeper snow accumulation and higher mean temperatures. The strong interactions identified between aspects of ambient environmental conditions and effects of OTCs suggest that a detailed knowledge of snow depth, temperature and irradiance levels enables us to predict how OTCs will modify the microclimate at a particular site and season. Such predictive power allows a better mechanistic understanding of observed biotic response to experimental warming studies and for more informed design of future experiments. However, a need remains to quantify OTC effects on water availability and wind speed (affecting, for example, drying rates and water stress) in combination with microclimate measurements at organism level.
|
|
| 4. |
|
|
| 5. |
- Gudmundsson, Jon Tomas, 1965-
(författare)
-
The high power impulse magnetron sputtering discharge as an ionized physical vapor deposition tool
- 2010
-
Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 84:12, s. 1360-1364
-
Tidskriftsartikel (refereegranskat)abstract
- Various magnetron sputtering tools have been developed that provide a high degree of ionization of the sputtered vapor referred to as ionized physical vapor deposition (IPVD). The ions can be controlled with respect to energy and direction as they arrive to the growth surface which allows for increased control of film properties during growth. Here, the design parameters for IPVD systems are briefly reviewed. The first sputter based IPVD systems utilized a secondary plasma source between the target and the substrate in order to generate a highly ionized sputtered vapor. High power impulse magnetron sputtering (HiPIMS) is a recent sputtering technique that utilizes IPVD where a high density plasma is created by applying high power pulses at low frequency and low duty cycle to a magnetron sputtering device. A summary of the key experimental findings for the HiPIMS discharge is given. Measurements of the temporal and spatial behavior of the plasma parameters indicate electron density peak, that expands from the target with a fixed velocity. The discharge develops from an inert sputtering gas dominated to a sputtered vapor dominated during the pulse. The high electron density results in a high degree of ionization of the deposition material.
|
|
| 6. |
|
|
| 7. |
- Huang, Shuo, et al.
(författare)
-
Ion Energy and Angular Distributions in a Dual-frequency Capacitively Coupled Chlorine Discharge
- 2014
-
Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 42:10, s. 2854-2855
-
Tidskriftsartikel (refereegranskat)abstract
- Ion energy distributions (IEDs) and ion angular distributions (IADs) of Cl2 + and Cl+ ions in a dual-frequency capacitively coupled chlorine discharge are obtained through a particle-in-cell/Monte Carlo simulation. Since the ion transit time is less than the low-frequency period, the ions respond to the instantaneous electric field in the sheath region, which leads to bimodal IEDs for Cl2 + and Cl+ ions. When transiting the sheath, the Cl+ ions experience a more collisional sheath than the Cl2 + ions. The IADs of Cl2 + and Cl+ ions at the surface are almost anisotropic. However, a secondary peak is found in the IAD of Cl+ ions, which can be ascribed to dissociative ionization reactions.
|
|
| 8. |
- Huo, Chunqing, et al.
(författare)
-
Gas rarefaction and the time evolution of long high-power impulse magnetron sputtering pulses
- 2012
-
Ingår i: Plasma sources science & technology. - : IOP Publishing. - 0963-0252 .- 1361-6595. ; 21:4, s. 045004-
-
Tidskriftsartikel (refereegranskat)abstract
- Model studies of 400 mu s long discharge pulses in high-power impulse magnetron sputtering have been made to study the gas dynamics and plasma chemistry in this type of pulsed processing plasma. Data are taken from an experiment using square voltage pulses applied to an Al target in an Ar atmosphere at 1.8 Pa. The study is limited to low power densities, < 0.5 kW cm(-2), in which the discharge is far away from the runaway self-sputtering mode. The model used is the ionization region model, a time-dependent plasma chemistry discharge model developed for the ionization region in magnetron sputtering discharges. It gives a close fit to the discharge current during the whole pulse, both an initial high-current transient and a later plateau value of constant lower current. The discharge current peak is found to precede a maximum in gas rarefaction of the order of Delta n(Ar)/n(Ar),(0) approximate to 50%. The time durations of the high-current transient, and of the rarefaction maximum, are determined by the time it takes to establish a steady-state diffusional refill of process gas from the surrounding volume. The dominating mechanism for gas rarefaction is ionization losses, with only about 30% due to the sputter wind kick-out process. During the high-current transient, the degree of sputtered metal ionization reaches 65-75%, and then drops to 30-35% in the plateau phase. The degree of self-sputtering (defined here as the metal ion fraction of the total ion current to the target) also varies during the pulse. It grows from zero at pulse start to a maximum of 65-70% coinciding in time with the maximum gas rarefaction, and then stabilizes in the range 40-45% during the plateau phase. The loss in deposition rate that can be attributed to the back-attraction of the ionized sputtered species is also estimated from the model. It is low during the initial 10-20 mu s, peaks around 60% during the high-current transient, and finally stabilizes around 30% during the plateau phase.
|
|
| 9. |
- Huo, Chunqing, et al.
(författare)
-
On sheath energization and Ohmic heating in sputtering magnetrons
- 2013
-
Ingår i: Plasma sources science & technology. - : Institute of Physics (IOP). - 0963-0252 .- 1361-6595. ; 22:4, s. 045005-
-
Tidskriftsartikel (refereegranskat)abstract
- In most models of sputtering magnetrons, the mechanism for energizing the electrons in the discharge is assumed to be sheath energization. In this process, secondary emitted electrons from the cathode surface are accelerated across the cathode sheath into the plasma, where they either ionize directly or transfer energy to the local lower energy electron population that subsequently ionizes the gas. In this work, we present new modeling results in support of an alternative electron energization mechanism. A model is experimentally constrained, by a fitting procedure, to match a set of experimental data taken over a large range in discharge powers in a high-power impulse magnetron sputtering (HiPIMS) device. When the model is matched to real data in this way, one finding is that the discharge can run with high power and large gas rarefaction without involving the mechanism of secondary electron emission by twice-ionized sputtered metal. The reason for this is that direct Ohmic heating of the plasma electrons is found to dominate over sheath energization by typically an order of magnitude. This holds from low power densities, as typical for dc magnetrons, to so high powers that the discharge is close to self-sputtering, i.e. dominated by the ionized vapor of the sputtered gas. The location of Ohmic heating is identified as an extended presheath with a potential drop of typically 100-150V. Such a feature, here indirectly derived from modeling, is in agreement with probe measurements of the potential profiles in other HiPIMS experiments, as well as in conventional dc magnetrons.
|
|
| 10. |
- Huo, Chunqing, et al.
(författare)
-
On the road to self-sputtering in high power impulse magnetron sputtering : particle balance and discharge characteristics
- 2014
-
Ingår i: Plasma sources science & technology. - : IOP Publishing. - 0963-0252 .- 1361-6595. ; 23:2, s. 025017-
-
Tidskriftsartikel (refereegranskat)abstract
- The onset and development of self-sputtering (SS) in a high power impulse magnetron sputtering (HiPIMS) discharge have been studied using a plasma chemical model and a set of experimental data, taken with an aluminum target and argon gas. The model is tailored to duplicate the discharge in which the data are taken. The pulses are long enough to include both an initial transient and a following steady state. The model is used to unravel how the internal discharge physics evolves with pulse power and time, and how it is related to features in the discharge current-voltage-time characteristics such as current densities, maxima, kinks and slopes. The connection between the self-sputter process and the discharge characteristics is quantified and discussed in terms of three parameters: a critical target current density J(crit) based on the maximum refill rate of process (argon) gas above the target, an SS recycling factor Pi(SS-recycle), and an approximation alpha a of the probabilities of ionization of species that come from the target (both sputtered metal and embedded argon atoms). For low power pulses, discharge voltages UD <= 380V with peak current densities below approximate to 0.2A cm(-2), the discharge is found to be dominated by process gas sputtering. In these pulses there is an initial current peak in time, associated with partial gas rarefaction, which is followed by a steady-state-like plateau in all parameters similar to direct current magnetron sputtering. In contrast, high power pulses, with U-D >= 500V and peak current densities above J(D) approximate to 1.6Acm(-2), make a transition to a discharge mode where SS dominates. The transition is found not to be driven by process gas rarefaction which is only about 10% at this time. Maximum gas rarefaction is found later in time and always after the initial peak in the discharge current. With increasing voltage, and pulse power, the discharge can be described as following a route where the role of SS increases in four steps: process gas sputtering, gas-sustained SS, self-sustained SS and SS runaway. At the highest voltage, 1000V, the discharge is very close to, but does not go into, the SS runaway mode. This absence of runaway is proposed to be connected to an unexpected finding: that twice ionized ions of the target species play almost no role in this discharge, not even at the highest powers. This reduces ionization by secondary-emitted energetic electrons almost to zero in the highest power range of the discharge.
|
|
