| 1. |
- Newton-Cheh, Christopher, et al.
(författare)
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Genome-wide association study identifies eight loci associated with blood pressure
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:6, s. 666-676
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Tidskriftsartikel (refereegranskat)abstract
- Elevated blood pressure is a common, heritable cause of cardiovascular disease worldwide. To date, identification of common genetic variants influencing blood pressure has proven challenging. We tested 2.5 million genotyped and imputed SNPs for association with systolic and diastolic blood pressure in 34,433 subjects of European ancestry from the Global BPgen consortium and followed up findings with direct genotyping (N <= 71,225 European ancestry, N <= 12,889 Indian Asian ancestry) and in silico comparison (CHARGE consortium, N 29,136). We identified association between systolic or diastolic blood pressure and common variants in eight regions near the CYP17A1 (P = 7 x 10(-24)), CYP1A2 (P = 1 x 10(-23)), FGF5 (P = 1 x 10(-21)), SH2B3 (P = 3 x 10(-18)), MTHFR (P = 2 x 10(-13)), c10orf107 (P = 1 x 10(-9)), ZNF652 (P = 5 x 10(-9)) and PLCD3 (P = 1 x 10(-8)) genes. All variants associated with continuous blood pressure were associated with dichotomous hypertension. These associations between common variants and blood pressure and hypertension offer mechanistic insights into the regulation of blood pressure and may point to novel targets for interventions to prevent cardiovascular disease.
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| 2. |
- Yamauchi, M., et al.
(författare)
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Magnetospheric solitary structure maintained by 3000 km/s ions as a cause of westward moving auroral bulge at 19 MLT
- 2009
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 27:7, s. 2947-2969
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Tidskriftsartikel (refereegranskat)abstract
- In the evening equatorial magnetosphere at about 4 R-E geocentric distance and 19 MLT, the four Cluster spacecraft observed a solitary structure with a width of about 1000 similar to 2000 km in the propagation direction. The solitary structure propagates sunward with about 5 similar to 10 km/s carrying sunward electric field (in the propagation direction) of up to about 10 mV/m (total potential drop of about 5 similar to 10 kV), depletion of magnetic field of about 25%, and a duskward E x B convection up to 50 km/s of He+ rich cold plasma without O+. At the same time, auroral images from the IMAGE satellite together with ground based geomagnetic field data showed a westward (sunward at this location) propagating auroral bulge at the magnetically conjugate ionosphere with the solitary structure. The solitary structure is maintained by flux enhancement of selectively 3000 km/s ions (about 50 keV for H+, 200 keV for He+, and 750 keV for O+). These ions are the main carrier of the diamagnetic current causing the magnetic depletion, whereas the polarization is maintained by different behavior of energetic ions and electrons. Corresponding to aurora, field-aligned accelerated ionospheric plasma of several keV appeared at Cluster from both hemispheres simultaneously. Together with good correspondence in location and propagation velocity between the auroral bulge and the solitary structure, this indicates that the sunward moving auroral bulge is caused by the sunward propagation of the solitary structure which is maintained by energetic ions. The solitary structure might also be the cause of Pi2-like magnetic variation that started simultaneously at Cluster location.
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| 3. |
- Arlos, Patrik, et al.
(författare)
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A Distributed Passive Measurement Infrastructure
- 2005
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe a distributed passive measurement infrastructure. Its goals are to reduce the cost and configuration effort per measurement. The infrastructure is scalable with regards to link speeds and measurement locations. A prototype is currently deployed at our university and a demo is online at http://inga.its.bth.se/projects/dpmi. The infrastructure differentiates between measurements and the analysis of measurements, this way the actual measurement equipment can focus on the practical issues of packet measurements. By using a modular approach the infrastructure can handle many different capturing devices. The infrastructure can also deal with the security and privacy aspects that might arise during measurements.
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| 4. |
- Figueiredo, Sonia, et al.
(författare)
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Temporal and spatial evolution of discrete auroral arcs as seen by Cluster
- 2005
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 23:7, s. 2531-2557
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Tidskriftsartikel (refereegranskat)abstract
- Two event studies are presented in this paper where intense convergent electric fields, with mapped intensities up to 1350 mV/m, are measured in the auroral upward current region by the Cluster spacecraft, at altitudes between 3 and 5 Earth radii. Both events are from May 2003, Southern Hemisphere, with equatorward crossings by the Cluster spacecraft of the pre-midnight auroral oval. Event 1 occurs during the end of the recovery phase of a strong substorm. A system of auroral arcs associated with convergent electric field structures, with a maximum perpendicular potential drop of about similar to 10 kV, and upflowing field-aligned currents with densities of 3 mu A/m(2) (mapped to the ionosphere), was detected at the boundary between the Plasma Sheet Boundary Layer (PSBL) and the Plasma Sheet (PS). The auroral arc structures evolve in shape and in magnitude on a timescale of tens of minutes, merging, broadening and intensifying, until finally fading away after about 50 min. Throughout this time, both the PS region and the auroral arc structure in its poleward part remain relatively fixed in space, reflecting the rather quiet auroral conditions during the end of the substorm. The auroral upward acceleration region is shown for this event to extend beyond 3.9 Earth radii altitude. Event 2 occurs during a more active period associated with the expansion phase of a moderate substorm. Images from the Defense Meteorological Satellite Program (DMSP) F13 spacecraft show that the Cluster spacecraft crossed the horn region of a surge-type aurora. Conjugated with the Cluster spacecraft crossing above the surge horn, the South Pole All Sky Imager recorded the motion and the temporal evolution of an east-west aligned auroral arc, 30 to 50 km wide. Intense electric field variations are measured by the Cluster spacecraft when crossing above the auroral arc structure, collocated with the density gradient at the PS poleward boundary, and coupled to intense upflowing field-aligned currents with mapped densities of up to 20 mu A/m(2). The surge horn consists of multiple arc structures which later merge into one structure and intensify at the PS poleward boundary. The surge horn and the associated PS region moved poleward with a velocity at the ionospheric level of 0.5 km/s, following the large-scale poleward expansion of the auroral oval associated with the substorm expansion phase.
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| 5. |
- Hong, Seung-Sun, et al.
(författare)
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TCPtransform : Property-Oriented TCP Traffic Transformation
- 2005
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Konferensbidrag (refereegranskat)abstract
- A TCPdump file captures not only packets but also various "properties" related to the live TCP sessions on the Internet. It is still an open problem to identify all the possible properties, if ever possible, and more importantly, which properties really matter for the consumers of this particular TCPdump file and how they are related to each other. However, it is quite clear that existing traffic replay tools, for the purpose of system evaluation, such as TCPreplay destroyed at least some of critical properties such as "ghost acknowledgment" (while the origin packet has never been delivered), which is a critical issue in conducting experimental evaluations for intrusion detection systems. In this paper, we present a software tool to transform an existing TCPdump file into another traffic file with different "properties". For instance, if the original traffic is being captured in a laboratory environment, the new file might "appear" to be captured in between US and Sweden. The transformation we have done here is "heuristically consistent" as there might be some hidden properties still being destroyed in the transformation process. One interesting application of our tool is to build long-term profiles to detect anomalous TCP attacks without really running the target application over the Internet. While, in this paper, we only focus on property-oriented traffic transformation, we have built and evaluated an interactive version of this tool, called TCPopera, to evaluate commercial intrusion prevention systems.
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| 6. |
- Johnson, Henric, et al.
(författare)
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Analysis of IPSec Performance
- 2005
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Konferensbidrag (refereegranskat)abstract
- In this paper we present the results of an experimental analysis of IPSec performance. IPSec serves as a security service to protect a communication session over unreliable networks using several cryptographic functions. The different IPSec features used to obtain confidentiality, authentication, replay protection, and integrity introduce performance costs brought about by the increased processing overhead. The performance parameters of interest are delay and throughput. However, there is a tradeoff between performance and security. The results of the performance tests indicate the vulnerability of a Denial-of-Service attack against a gateway running IPSec due to resource exhaustion.
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| 7. |
- Johnson, Henric, et al.
(författare)
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Hierarchical Defense Structure for Mitigating DoS Attacks
- 2006
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Konferensbidrag (refereegranskat)abstract
- This paper provides the contribution of mitigating a Denial-of-Service (DoS) attack via a developed hierarchical defense structure with proactive functionality. An important aspect is the tradeoff between performance and security. This novel hierarchical architecture is presented with lightweight authentication protocols acting as a classifier to deny access to harmful traffic. An empirical test of the proposed structure has been performed and results are reported which display the capability of the structure to filter and separate the attack traffic before reaching the target of an IPSec gateway. Thus, the filtering of traffic is performed without being the target itself for new resource exhaustion attacks. The considered IPSec environment is based on IPSec gateways for the low-end market, i.e., for small businesses or private networks.
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| 8. |
- Pistorius, Pierre A., et al.
(författare)
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A demographic comparison of two Nordic populations of Greylag Geese Anser anser
- 2007
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Ingår i: Ibis. - 0019-1019. ; 149:3, s. 553-563
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Tidskriftsartikel (refereegranskat)abstract
- Greylag Geese Anser anser have been neck-banded on an annual basis in Scania, southern Sweden since 1984 and in Norway since 1986 as part of a Nordic Greylag project. This has yielded a large database of resightings, which we used here to estimate and compare survival rates between the two populations by means of mark-recapture models. Estimated adult survival was sex-dependent in the Scanian population, probably a result of differential neck band retention rates in this population. Mean juvenile survival was about 12% higher in the Scanian population (0.603 vs. 0.485). Adult survival in the Norwegian population was 0.728 (males 0.733; females 0.725), and in males and females from the Scanian population was 0.711 (0.752 after accounting for higher neck band loss in males) and 0.771, respectively. Over the course of the study, juvenile survival in the Scanian population increased substantially, and adult survival was constant, whereas both these parameters declined in the Norwegian population. This study demonstrates that the two Nordic populations are demographically distinct and gives further support to the notion that they should be treated as separate management units. The decline of 10% in adult survival in the Norwegian population, the cause of which still remains uncertain, is likely to have had a major impact on the growth of this population.
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| 9. |
- Schröder, Arne, 1974-, et al.
(författare)
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Invasion success depends on invader body size in a size-structured mixed predation-competition system
- 2009
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons, Inc. - 0021-8790 .- 1365-2656. ; 78:6, s. 1152-1162
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Tidskriftsartikel (refereegranskat)abstract
- 1. The size of an individual is an important determinant of its trophic position and the type of interactions it engages in with other heterospecific and conspecific individuals. Consequently an individual's ecological role in a community changes with its body size over ontogeny, leading to that trophic interactions between individuals are a size-dependent and ontogenetically variable mixture of competition and predation. 2. Because differently sized individuals thus experience different biotic environments, invasion success may be determined by the body size of the invaders. Invasion outcome may also depend on the productivity of the system as productivity influences the biotic environment. 3. In a laboratory experiment with two poeciliid fishes the body size of the invading individuals and the daily amount of food supplied were manipulated. 4. Large invaders established persistent populations and drove the resident population to extinction in 10 out of 12 cases, while small invaders failed in 10 out of 12 trials. Stable coexistence was virtually absent. Invasion outcome was independent of productivity. 5. Further analyses suggest that small invaders experienced a competitive recruitment bottleneck imposed on them by the resident population. In contrast, large invaders preyed on the juveniles of the resident population. This predation allowed the large invaders to establish successfully by decreasing the resident population densities and thus breaking the bottleneck. 6. The results strongly suggest that the size distribution of invaders affects their ability to invade, an implication so far neglected in life-history omnivory systems. The findings are further in agreement with predictions of life-history omnivory theory, that size-structured interactions demote coexistence along a productivity gradient.
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| 10. |
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