| 1. |
- Achterberg, A., et al.
(författare)
-
Five years of searches for point sources of astrophysical neutrinos with the AMANDA-II neutrino telescope
- 2007
-
Ingår i: Physical Review D. Particles, fields, gravitation, and cosmology. - 1550-7998. ; 75:10, s. 102001-
-
Tidskriftsartikel (refereegranskat)abstract
- We report the results of a five-year survey of the northern sky to search for point sources of high energy neutrinos. The search was performed on the data collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with a live time of 1001 days. The sample of selected events consists of 4282 upward going muon tracks with high reconstruction quality and an energy larger than about 100 GeV. We found no indication of point sources of neutrinos and set 90% confidence level flux upper limits for an all-sky search and also for a catalog of 32 selected sources. For the all-sky search, our average (over declination and right ascension) experimentally observed upper limit Phi0=((E/(1 TeV)))gamma·((d Phi)/dE) to a point source flux of muon and tau neutrino (detected as muons arising from taus) is Phinu[sub mu] + [overline nu ][sub mu]0+Phinu[sub tau] + [overline nu ][sub tau]0=11.1× 10-11 TeV-1 cm-2 s-1, in the energy range between 1.6 TeV and 2.5 PeV for a flavor ratio Phinu[sub mu] + [overline nu ][sub mu]0/Phinu[sub tau] + [overline nu ][sub tau]0=1 and assuming a spectral index gamma=2. It should be noticed that this is the first time we set upper limits to the flux of muon and tau neutrinos. In previous papers we provided muon neutrino upper limits only neglecting the sensitivity to a signal from tau neutrinos, which improves the limits by 10% to 16%. The value of the average upper limit presented in this work corresponds to twice the limit on the muon neutrino flux Phinu[sub mu] + [overline nu ][sub mu]0=5.5×10-11 TeV-1 cm-2 s-1. A stacking analysis for preselected active galactic nuclei and a search based on the angular separation of the events were also performed. We report the most stringent flux upper limits to date, including the results of a detailed assessment of systematic uncertainties.
|
|
| 2. |
- Berglund, Per, et al.
(författare)
-
Linking Education and Research : A Roadmap for Higher Education Institutions at the Dawn of the Knowledge Society
- 2019
-
Ingår i: Linking education and research. - Basel, Switzerland : MDPI. ; , s. 11-33
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In an era characterized by a move towards a “knowledge society”, universities are central in fostering “knowledgeability”, that is the reflexive understanding of knowledge in knowledge societies. The objective of “knowledgeability” can be met through creating a stronger link between education and research. Furthermore, overall student performance, for example in critical thinking and problem solving, can be improved if research-related activities are incorporated into the curriculum.The aim of this paper is to use international examples to discuss the research- education nexus from four different perspectives, namely context, policy, implementation and quality, with case studies from higher education institutions in Singapore and Sweden.We suggest that different integrative technologies can be used to enhance the links, but it will be essential to consider the inputs of training, service and support in using new technology. Interestingly, the act of evaluating the link between education and research will increase awareness of this linkage by stakeholders involved in both education and research. In turn the link can be strengthened, contributing to increased quality in both education and research.
|
|
| 3. |
|
|
| 4. |
- Gouldstone, Andrew, et al.
(författare)
-
Onset of plastic yielding in thin metal lines deposited on substrates
- 1999
-
Ingår i: Scripta Materialia. - 1359-6462 .- 1872-8456. ; 41:3, s. 297-304
-
Tidskriftsartikel (refereegranskat)abstract
- A thermoelastic analysis of patterned lines on substrates to determine the critical conditions for the onset of yielding is investigated, which provides a new analytical tool for determining the yield properties of lines relative to those of films of the same thickness. Verification of the theory is provided with the aid of finite element simulations, and a method for experimentally extracting the plastic properties of lines is also outlined.
|
|
| 5. |
- Gudmundson, Peter, et al.
(författare)
-
Stresses in thin films and interconnect lines
- 2002
-
Ingår i: Microelectronic Engineering. - 0167-9317 .- 1873-5568. ; 60:1-2, s. 17-29
-
Tidskriftsartikel (refereegranskat)abstract
- The mechanical behavior of thin films and interconnect lines is investigated. Firstly, theoretical models of thermal stress evolution in thin films and passivated or unpassivated lines are considered. Secondly, the effect of texture in a copper thin film with a columnar grain structure is studied from a theoretical point of view. The film consists of three different constituents with (111), (100) and randomly oriented texture. Global properties as well as local stress distributions are considered in detail within a thermoelastic framework. The results are in qualitative agreement with available experimental results. Implications with regards to plastic behavior are briefly discussed. Finally, the potential of the curvature measurement technique for experimental stress evaluation in thin films is considered for initially flat and curved substrate/film systems.
|
|
| 6. |
- Scarpati, Jose, et al.
(författare)
-
Prediction of Engine Noise using Parameterized Combustion Pressure Curves
- 2007
-
Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
-
Tidskriftsartikel (refereegranskat)abstract
- A parameterization for combustion chamber cylinderpressures is tuned to measurements on an inline 6cylinder Diesel engine at different operating conditions.Both measured and modeled signals are filtered in thefrequency domain and according to the so called Lucasattenuation. Two different estimates of engine radiatednoise are obtained and compared in this fashion. Theinfluence of physically meaningful parameters on thefrequency contents of the final noise level is analyzed,as well as the contribution of the pressure trace of themotored engine. The scattering of data in the pressuresignal is calculated as a function of the crank angleallowing for statistical considerations.
|
|
| 7. |
- Stattin, Eva-Lena, et al.
(författare)
-
SNX10 gene mutation leading to osteopetrosis with dysfunctional osteoclasts
- 2017
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- Autosomal recessive osteopetrosis (ARO) is a heterogeneous disorder, characterized by defective osteoclastic resorption of bone that results in increased bone density. We have studied nine individuals with an intermediate form of ARO, from the county of Vasterbotten in Northern Sweden. All afflicted individuals had an onset in early infancy with optic atrophy, and in four patients anemia was present at diagnosis. Tonsillar herniation, foramen magnum stenosis, and severe osteomyelitis of the jaw were common clinical features. Whole exome sequencing, verified by Sanger sequencing, identified a splice site mutation c.212 + 1 G > T in the SNX10 gene encoding sorting nexin 10. Sequence analysis of the SNX10 transcript in patients revealed activation of a cryptic splice site in intron 4 resulting in a frame shift and a premature stop (p.S66Nfs * 15). Haplotype analysis showed that all cases originated from a single mutational event, and the age of the mutation was estimated to be approximately 950 years. Functional analysis of osteoclast progenitors isolated from peripheral blood of patients revealed that stimulation with receptor activator of nuclear factor kappa-B ligand (RANKL) resulted in a robust formation of large, multinucleated osteoclasts which generated sealing zones; however these osteoclasts exhibited defective ruffled borders and were unable to resorb bone in vitro.
|
|
| 8. |
- Wikström, Adam, et al.
(författare)
-
Analysis of average thermal stresses in passivated metal interconnects
- 1999
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 86:11, s. 6088-6095
-
Tidskriftsartikel (refereegranskat)abstract
- Volume-averaged thermal stresses in passivated metal interconnects on Si substrates are derived for situations where the thickness to width ratio of the interconnect lines is "small" or "large." The analysis provides different components of volume-averaged stresses for the most general case of thermal and elastic anisotropy in the passivation layer, the interconnect line, and the substrate. It is shown that the theoretical predictions, particularly those for the hydrostatic stresses, are in agreement with detailed finite element calculations for a wide range of line and passivation geometries of practical interest. The theoretical predictions of average hydrostatic stresses are also found to be in reasonable agreement with available experimental results for thermal stresses derived from x-ray diffraction measurements on passivated Cu lines. The present theoretical results are shown to be far more accurate than prior stress analyses for periodic passivated lines based on Eshelby's theory of inclusions.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Wikström, Adam, et al.
(författare)
-
Passivated interconnect lines: Thermomechanical analysis and curvature measurements
- 2000
-
Ingår i: Materials Research Society Symposium - Proceedings. - : Materials Research Society. ; , s. 439-444
-
Konferensbidrag (refereegranskat)abstract
- It is well known that curvature measurements may be used to obtain volume averaged stresses in thin continuous films and unpassivated lines without knowledge of the material properties of the film or lines. However, recently a method was presented which makes it possible to use curvature measurements also for the determination of volume averaged stresses in passivated lines. Since the problem is statically indeterminate the method requires knowledge of the material properties of the lines and passivation. The sensitivity of the method to uncertainties in material properties and curvature data is here investigated by utilizing the finite element method for anisotropic Cu or Al lines embedded in SiO2 passivation. Furthermore, the method is extended to cover the case of different stress-free temperatures for the lines and passivation respectively.
|
|
| 13. |
- Wikström, Adam, et al.
(författare)
-
Stresses in passivated lines from curvature measurements
- 2000
-
Ingår i: Acta Materialia. - 1359-6454 .- 1873-2453. ; 48:10, s. 2429-2434
-
Tidskriftsartikel (refereegranskat)abstract
- An exact expression is presented which enables the determination of volume-averaged thermoelastic stresses in passivated lines based on information from curvature measurements. This method, which is Valid for lines of arbitrary in-plane shape, requires knowledge of the material properties of the line and passivation. The sensitivity of the line stress estimates to uncertainties in curvature data for a typical line/passivation geometry is investigated in detail. It is concluded that the present approach is well suited for Al or Cu lines embedded in SiO2 passivation. In the particular case of coinciding shear moduli or Poisson ratios for the line and passivation, it is shown that the method breaks down and only certain linear combinations of the line stress components may be determined.
|
|
| 14. |
- Wikström, Adam, et al.
(författare)
-
Stresses in Thin Coatings from Curvature Measurements on Non-Planar Substrates
- 2001
-
Ingår i: Materials Research Society Symposium - Proceedings. ; , s. Z10.4.1-6
-
Konferensbidrag (refereegranskat)abstract
- Mechanical elastic and inelastic properties of thin coatings are often studied by means of the curvature measurement technique in combination with the Stoney formula. It is then implicitly assumed that the elastic substrate is initially flat which implies that the curvatures theoretically remain constant over the substrate. If the substrate has a slight initial curvature, a different situation arises. In this case, the curvatures will vary over the substrate. It has recently been shown that in spite of this, the stresses that appear in the thin coating will remain constant over the surface of the substrate. Therefore, measured curvatures can generally not be used to extract layer stresses without a proper compensation for the initial curvature. A general method for the extraction of mechanical properties from curvature measurements on non-planar substrates is outlined. The method is valid for linear as well as non-linear shell theories. The compensation needed to evaluate a coating on a circular substrate with spherical initial curvature is studied for all relevant parameters. The results are particularly discussed in relation to curvature measurements on silicon wafers.
|
|
| 15. |
- Wikström, Adam, et al.
(författare)
-
Thermal deformation of initially curved substrates coated by thin inhomogeneous layers
- 2001
-
Ingår i: Journal of applied mechanics. - : ASME International. - 0021-8936 .- 1528-9036. ; 68:2, s. 298-303
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal curvature changes and membrane strains are analyzed for elastic shallow shell substrates which are coated by thin, generally inelastic, inhomogeneous and anisotropic layers. The analysis is restricted to linear kinematics. It is shown that the deformation is governed by the corresponding solution for a flat substrate and a correction due to the initial curvature. The correction is determined from a shallow shell problem for the bare substrate with a loading expressed by the coefficients of thermal curvature for the substrate/layer system. For constant initial curvature, certain analytic solutions are presented. For situations when the initial deflection of the substrate is much larger than the substrate thickness, a boundary layer solution is derived. In the particular case of a circular isotropic substrate with a spherical initial curvature and a coating of arbitrary anisotropy, the solution is presented in closed form. For nonflat substrates, measured curvatures can generally not be used to extract layer stresses without a proper compensation for the initial curvature. In this paper, it is explicitly presented how to accurately compensate for a spherical initial curvature. The results are particularly discussed in relation to curvature measurements on Silicon substrates.
|
|
| 16. |
|
|
| 17. |
- Wikström, Adam, et al.
(författare)
-
Thermoelastic analysis of periodic thin lines deposited on a substrate
- 1999
-
Ingår i: Journal of the mechanics and physics of solids. - 0022-5096 .- 1873-4782. ; 47:5, s. 1113-1130
-
Tidskriftsartikel (refereegranskat)abstract
- Thermoelastic stresses and curvatures arising from patterned thin lines on initially flat isotropic substrates are analyzed. A connection is made between substrates with patterned lines and laminated anisotropic composites containing transverse matrix cracks. Using this analogy along with anisotropic plate theories, approximate analytical expressions are derived for volume-averaged stresses as well as curvatures along and normal to the lines, for any thickness, width and spacing of the lines. The predictions of the analysis are shown to compare favorably with finite element simulations of stresses and curvatures for Si substrates with Al, Cu or SiO2 lines. The predictions also match prior experimental measurements of curvatures along and normal to patterned SiO2 lines on Si wafers, and further capture the general experimental trends reported previously for curvature evolutions in Si wafers with Al lines. The model presented here thus provides a very convenient and simple analytical tool for extracting stresses in thin lines on substrates from a knowledge of experimentally determined film stress, thereby circumventing the need for detailed computations for a wide range of unpassivated line geo metries of interest in microelectronic applications.
|
|
| 18. |
- Wikström, Jakob D., et al.
(författare)
-
Hormone-induced mitochondrial fission is utilized by brown adipocytes as an amplification pathway for energy expenditure
- 2014
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 33:5, s. 418-436
-
Tidskriftsartikel (refereegranskat)abstract
- Adrenergic stimulation of brown adipocytes (BA) induces mitochondrial uncoupling, thereby increasing energy expenditure by shifting nutrient oxidation towards thermogenesis. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically-induced changes in energy expenditure. The sympathetic neurotransmitter Norepinephrine (NE) induced complete and rapid mitochondrial fragmentation in BA, characterized by Drp1 phosphorylation and Opa1 cleavage. Mechanistically, NE-mediated Drp1 phosphorylation was dependent on Protein Kinase-A (PKA) activity, whereas Opa1 cleavage required mitochondrial depolarization mediated by FFAs released as a result of lipolysis. This change in mitochondrial architecture was observed both in primary cultures and brown adipose tissue from cold-exposed mice. Mitochondrial uncoupling induced by NE in brown adipocytes was reduced by inhibition of mitochondrial fission through transient Drp1 DN overexpression. Furthermore, forced mitochondrial fragmentation in BA through Mfn2 knock down increased the capacity of exogenous FFAs to increase energy expenditure. These results suggest that, in addition to its ability to stimulate lipolysis, NE induces energy expenditure in BA by promoting mitochondrial fragmentation. Together these data reveal that adrenergically-induced changes to mitochondrial dynamics are required for BA thermogenic activation and for the control of energy expenditure.
|
|
