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Karazisis, D., Petronis, S., Agheli, H., Emanuelsson, L., Norlindh, B., Johansson, A., . . . Omar, O. (2017). The influence of controlled surface nanotopography on the early biological events of osseointegration.. Acta Biomaterialia, 53, 559-571
Open this publication in new window or tab >>The influence of controlled surface nanotopography on the early biological events of osseointegration.
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2017 (English)In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 53, p. 559-571Article in journal (Refereed) Published
Abstract [en]

The early cell and tissue interactions with nanopatterned titanium implants are insufficiently described in vivo. A limitation has been to transfer a pre-determined, well-controlled nanotopography to 3D titanium implants, without affecting other surface parameters, including surface microtopography and chemistry. This in vivo study aimed to investigate the early cellular and molecular events at the bone interface with screw-shaped titanium implants superimposed with controlled nanotopography. Polished and machined titanium implants were firstly patterned with 75-nm semispherical protrusions. Polished and machined implants without nano-patterns were designated as controls. Thereafter, all nanopatterned and control implants were sputter-coated with a 30nm titanium layer to unify the surface chemistry. The implants were inserted in rat tibiae and samples were harvested after 12h, 1d and 3d. In one group, the implants were unscrewed and the implant-adherent cells were analyzed using quantitative polymerase chain reaction. In another group, implants with surrounding bone were harvested en bloc for histology and immunohistochemistry. The results showed that nanotopography downregulated the expression of monocyte chemoattractant protein-1 (MCP-1), at 1d, and triggered the expression of osteocalcin (OC) at 3d. This was in parallel with a relatively lower number of recruited CD68-positive macrophages in the tissue surrounding the nanopatterned implants. Moreover, a higher proportion of newly formed osteoid and woven bone was found at the nanopatterned implants at 3d. It is concluded that nanotopography, per se, attenuates the inflammatory process and enhances the osteogenic response during the early phase of osseointegration. This nanotopography-induced effect appeared to be independent of the underlying microscale topography.

STATEMENT OF SIGNIFICANCE: This study provides a first line of evidence that pre-determined nanopatterns on clinically relevant, screw-shaped, titanium implants can be recognized by cells in the complex in vivo environment. Until now, most of the knowledge relating to cell interactions with nanopatterned surfaces has been acquired from in vitro studies involving mostly two-dimensional nanopatterned surfaces of varying chemical composition. We have managed to superimpose pre-determined nanoscale topography on polished and micro-rough, screw-shaped, implants, without changes in the microscale topography or chemistry. This was achieved by colloidal lithography in combination with a thin titanium film coating on top of both nanopatterned and control implants. The early events of osseointegration were evaluated at the bone interface to these implants. The results revealed that nanotopography, as such, elicits downregulatory effects on the early recruitment and activity of inflammatory cells while enhancing osteogenic activity and woven bone formation.

Keywords
Gene expression, In vivo, Nanotopography, Osseointegration, Titanium
National Category
Biomaterials Science
Identifiers
urn:nbn:se:ri:diva-29220 (URN)10.1016/j.actbio.2017.02.026 (DOI)28232253 (PubMedID)2-s2.0-85014028726 (Scopus ID)
Funder
VINNOVARegion Västra Götaland
Available from: 2017-04-05 Created: 2017-04-05 Last updated: 2019-01-03Bibliographically approved
Drejhammar, F. & Rasmusson, L. (2014). BEAMJIT: a just-in-time compiling runtime for Erlang (7ed.). In: : . Paper presented at The Thirteenth ACM SIGPLAN Workshop on Erlang.
Open this publication in new window or tab >>BEAMJIT: a just-in-time compiling runtime for Erlang
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

BEAMJIT is a tracing just-in-time compiling runtime for the Erlang programming language. The core parts of BEAMJIT are synthesized from the C source code of BEAM, the reference Erlang abstract machine. The source code for BEAM's instructions is extracted automatically from BEAM's emulator loop. A tracing version of the abstract machine, as well as a code generator are synthesized. BEAMJIT uses the LLVM toolkit for optimization and native code emission. The automatic synthesis process greatly reduces the amount of manual work required to maintain a just-in-time compiler as it automatically tracks the BEAM system. The performance is evaluated with HiPE's, the Erlang ahead-of-time native compiler, benchmark suite. For most benchmarks BEAMJIT delivers a performance improvement compared to BEAM, although in some cases, with known causes, it fails to deliver a performance boost. BEAMJIT does not yet match the performance of HiPE mainly because it does not yet implement Erlang specific optimizations such as boxing/unboxing elimination and a deep understanding of BIFs. Despite this BEAMJIT, for some benchmarks, reduces the runtime with up to 40\%.

National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-24378 (URN)10.1145/2633448.2633450 (DOI)
Conference
The Thirteenth ACM SIGPLAN Workshop on Erlang
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2019-06-20Bibliographically approved
Rasmusson, L. & Corcoran, D. (2013). Performance overhead of KVM on Linux 3.9 on ARM Cortex-A15 (9ed.). Proceedings of Workshop on Virtualization for Real-Time Embedded Systems
Open this publication in new window or tab >>Performance overhead of KVM on Linux 3.9 on ARM Cortex-A15
2013 (English)In: Proceedings of Workshop on Virtualization for Real-Time Embedded SystemsArticle in journal (Refereed) Published
Abstract [en]

 A number of simple performance measurements on network, CPU and disk speed were done on a dual ARM Cortex- A15 machine running Linux inside a KVM virtual machine that uses virtio disk and networking. Unexpected behaviour was observed in the CPU and memory intensive benchmarks, and in the networking benchmarks. The average overhead of running inside KVM is between zero and 30 percent when the host is lightly loaded (running only the system software and the necessary qemu-system-arm virtualization code), but the relative overhead increases when both host and VM is busy. We conjecture that this is related to the scheduling inside the host Linux.

Keywords
ARM Cortex-A15, HVM, Linux KVM, virtualization, performance
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-24245 (URN)
Projects
hyperv
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-13Bibliographically approved
Rasmusson, L. & Rajabi Nasab, M. (2012). Hypervisor Integrity Measurement Assistant (11ed.). Kista, Sweden: Swedish Institute of Computer Science
Open this publication in new window or tab >>Hypervisor Integrity Measurement Assistant
2012 (English)Report (Other academic)
Abstract [en]

An attacker who has gained access to a computer may want to upload or modify configuration files, etc., and run arbitrary programs of his choice. We can severely restrict the power of the attacker by having a white-list of approved file checksums and preventing the kernel from loading loading any file with a bad checksum. The check may be placed in the kernel, but that requires a kernel that is prepared for it. The check may also be placed in a hypervisor which intercepts and prevents the kernel from loading a bad file. We describe the implementation of and give performance results for two systems. In one the checksumming, or integrity measurement, and decision is performed by the hypervisor instead of the OS. In the other only the final integrity decision is done in the hypervisor. By moving the integrity check out from the VM kernel it becomes harder for the intruder to bypass the check. We conclude that it is technically possible to put file integrity control into the hypervisor, both for kernels without and with pre-compiled support for integrity measurement.

Place, publisher, year, edition, pages
Kista, Sweden: Swedish Institute of Computer Science, 2012 Edition: 11
Series
SICS Technical Report, ISSN 1100-3154 ; 2012:06
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-24054 (URN)
Projects
TESPEVSCNS
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-13Bibliographically approved
Rasmusson, L. & Aslam, M. (2012). Protecting Private Data in the Cloud (16ed.). In: Proceedings of The 2nd International Conference on Cloud Computing and Services Science, CLOSER 2012: . Paper presented at The 2nd International Conference on Cloud Computing and Services Science, CLOSER 2012.
Open this publication in new window or tab >>Protecting Private Data in the Cloud
2012 (English)In: Proceedings of The 2nd International Conference on Cloud Computing and Services Science, CLOSER 2012, 2012, 16Conference paper, Published paper (Refereed)
Abstract [en]

Companies that process business critical and secret data are reluctant to use utility and cloud computing for the risk that their data gets stolen by rogue system administrators at the hosting company. We describe a system organization that prevents host administrators from directly accessing or installing eaves-dropping software on the machine that holds the client's valuable data. Clients are monitored via machine code probes that are inlined into the clients' programs at runtime. The system enables the cloud provider to install and remove software probes into the machine code without stopping the client's program, and it prevents the provider from installing probes not granted by the client.

Keywords
cloud computing, virtualization, trusted computing, binary translation
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-24020 (URN)
Conference
The 2nd International Conference on Cloud Computing and Services Science, CLOSER 2012
Projects
TESPEV
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-13Bibliographically approved
Aslam, M., Gehrmann, C., Rasmusson, L. & Björkman, M. (2012). Securely Launching Virtual Machines on Trustworthy Platforms in a Public Cloud (12ed.). In: : . Paper presented at International Conference on Cloud Computing and Services Science, CLOSER 2012.
Open this publication in new window or tab >>Securely Launching Virtual Machines on Trustworthy Platforms in a Public Cloud
2012 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we consider the Infrastructure-as-a-Service (IaaS) cloud model which allows cloud users to run their own virtual machines (VMs) on available cloud computing resources. IaaS gives enterprises the possibility to outsource their process workloads with minimal effort and expense. However, one major problem with existing approaches of cloud leasing, is that the users can only get contractual guarantees regarding the integrity of the offered platforms. The fact that the IaaS user himself or herself cannot verify the provider promised cloud platform integrity, is a security risk which threatens to prevent the IaaS business in general. In this paper we address this issue and propose a novel secure VM launch protocol using Trusted Computing techniques. This protocol allows the cloud IaaS users to securely bind the VM to a trusted computer configuration such that the clear text VM only will run on a platform that has been booted into a trustworthy state. This capability builds user confidence and can serve as an important enabler for creating trust in public clouds. We evaluate the feasibility of our proposed protocol via a full scale system implementation and perform a system security analysis.

National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-23987 (URN)
Conference
International Conference on Cloud Computing and Services Science, CLOSER 2012
Projects
TESPEVS
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-16Bibliographically approved
Bjurling, B., Rasmusson, L. & Johansson, U. M. (2008). Qualitative policies for bandwidth priorities in ad-hoc networks (1ed.). In: Proc. IEEE 27th Conference on Computer Communications: . Paper presented at First International Workshop on Automated Network Management, April 13-18, 2008, Phoenix, AZ, USA.
Open this publication in new window or tab >>Qualitative policies for bandwidth priorities in ad-hoc networks
2008 (English)In: Proc. IEEE 27th Conference on Computer Communications, 2008, 1Conference paper, Published paper (Refereed)
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-22901 (URN)
Conference
First International Workshop on Automated Network Management, April 13-18, 2008, Phoenix, AZ, USA
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-13Bibliographically approved
Rasmusson, L. & Janson, S. (2007). Libra, a Multi-hop Radio Network Bandwidth Market (1ed.). In: : . Paper presented at 7th Scandinavian Workshop on Wireless Ad-hoc & Sensor Networks (ADHOC'07), 2-3 May 2007, Stockholm, Sweden.
Open this publication in new window or tab >>Libra, a Multi-hop Radio Network Bandwidth Market
2007 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Libra is a two-level market which assigns fractional shares of time to the transmitting nodes in local regions of a multi-hop network. In Libra, users are assigned budgets by management and users assign funding to services within their budget limits. The purpose is to prioritize users and also optimize network utilization by preventing source nodes from injecting too much traffic into the network and thereby causing downstream packet loss. All transmitting nodes sell capacity in the region surrounding them, and buy capacity from their neighbors in order to be able to transmit. Streams buy capacity from each of the nodes on their paths, thus streams that cross the same region compete directly for the bandwidth in that region. Prices are adjusted incrementally on both levels.

Publisher
p. 5
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-22274 (URN)
Conference
7th Scandinavian Workshop on Wireless Ad-hoc & Sensor Networks (ADHOC'07), 2-3 May 2007, Stockholm, Sweden
Projects
LIBRA
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-13Bibliographically approved
Linnarsson, S., Lönnerberg, P., Olden, M., Aurell, E., Carlsson, M., Ekman, J., . . . Rasmusson, L. (2003). METHODS FOR PROFILING MOLECULES WITH AN OBJECTIVE FUNCTION (18ed.). .
Open this publication in new window or tab >>METHODS FOR PROFILING MOLECULES WITH AN OBJECTIVE FUNCTION
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2003 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

Methods relating to profiling and/or identifying molecules in a sample, particularly chemical or biological molecules contained in an experimental sample using measured data about molecules actually present and known information about candidate molecules that may be present. Information tags can be assigned to candidates. This may be achieved with a high degree of accuracy and a low false positive rate by minimising the effect of one or more possible sources of error. An objective goal (assignment) may be optimised by linear programming or by mixed integer programming

National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-23634 (URN)
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-23Bibliographically approved
Rasmusson, L. & Aurell, E. (2003). Simulation of a network capacity market and three middle-man strategies to price and sell dynamically routed point-to-point connection (1ed.). In: : . Paper presented at 9th International Conference on Information Systems Analysis and Synthesis (ISAS), 31 July - 2 Aug 2003, Orlando, Florida, USA.
Open this publication in new window or tab >>Simulation of a network capacity market and three middle-man strategies to price and sell dynamically routed point-to-point connection
2003 (English)Conference paper, Published paper (Refereed)
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-22433 (URN)
Conference
9th International Conference on Information Systems Analysis and Synthesis (ISAS), 31 July - 2 Aug 2003, Orlando, Florida, USA
Available from: 2016-10-31 Created: 2016-10-31 Last updated: 2018-08-13Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6173-599x

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