| 11. |
- Aghaeinezhadfirouzja, Saeid, et al.
(författare)
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Practical 3-D beam pattern based channel modeling for multi-polarized massive MIMO systems
- 2018
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 18:4
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a practical non-stationary three-dimensional (3-D) channel models for massive multiple-input multiple-output (MIMO) systems, considering beam patterns for different antenna elements, is proposed. The beam patterns using dipole antenna elements with different phase excitation toward the different direction of travels (DoTs) contributes various correlation weights for rays related towards/from the cluster, thus providing different elevation angle of arrivals (EAoAs) and elevation angle of departures (EAoDs) for each antenna element. These include the movements of the user that makes our channel to be a non-stationary model of clusters at the receiver (RX) on both the time and array axes. In addition, their impacts on 3-D massive MIMO channels are investigated via statistical properties including received spatial correlation. Additionally, the impact of elevation/azimuth angles of arrival on received spatial correlation is discussed. Furthermore, experimental validation of the proposed 3-D channel models on azimuth and elevation angles of the polarized antenna are specifically evaluated and compared through simulations. The proposed 3-D generic models are verified using relevant measurement data.
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| 12. |
- Aghaeipour, Mahtab, et al.
(författare)
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Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors
- 2018
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Ingår i: Nanophotonics. - Berlin : Walter de Gruyter GmbH. - 2192-8614. ; 7:5, s. 819-825
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Tidskriftsartikel (refereegranskat)abstract
- A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.
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| 13. |
- Agvald-Öhman, C, et al.
(författare)
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Multiresistant coagulase-negative staphylococci disseminate frequently between intubated patients in a multidisciplinary intensive care unit
- 2004
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Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 8:1, s. R42-R47
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Tidskriftsartikel (refereegranskat)abstract
- Introduction The intensive care unit is burdened with a high frequency of nosocomial infections often caused by multiresistant nosocomial pathogens. Coagulase-negative staphylococci (CoNS) are reported to be the third causative agent of nosocomial infections and the most frequent cause of nosocomial bloodstream infections. CoNS are a part of the normal microflora of skin but can also colonize the nasal mucosa, the lower airways and invasive devices. The main aim of the present study was to investigate colonization and the rate of cross-transmissions of CoNS between intubated patients in a multidisciplinary intensive care unit. Materials and methods Twenty consecutive patients, ventilated for at least 3 days, were included. Samples were collected from the upper and lower airways. All samples were cultured quantitatively and CoNS were identified by morphology and biochemical tests. A total of 199 CoNS isolates from 17 patients were genetically fingerprinted by pulsed-field gel electrophoresis in order to identify clones and to monitor dissemination within and between patients. Results An unexpected high number of transmission events were detected. Five genotypes were each isolated from two or more patients, and 14/20 patients were involved in at least one and up to eight probable transmission events. Conclusions A frequent transmission of CoNS was found between patients in the intensive care unit. Although transmission of bacteria does not necessarily lead to infection, it is nevertheless an indication that infection control measures can be improved.
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| 14. |
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| 15. |
- Ahlström, F., et al.
(författare)
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Performance indicators of textile reverse logistics
- 2020
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Ingår i: IOP Conference Series: Earth and Environmental Science. - : IOP Publishing. - 1755-1307 .- 1755-1315.
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Konferensbidrag (refereegranskat)abstract
- © Published under licence by IOP Publishing Ltd. The reverse supply chain has gained increased attention across industries due to the high product return rates. Many strategic and economic benefits can be reaped by efficiently managing the reverse supply chain, such as; cost reduction and enhanced environmental performance. Despite the acknowledgement of the available advantages that can be reaped, there is an overall lack of academic research concerning performance metrics, in particular KPIs (Key Performance Indicators), that can help in managing reverse supply chains. Moreover, industry-specific KPIs have not been explored thoroughly. The apparel industry is currently plagued by high return rates, which suggests that it is even more important for clothing retailers to look over their reverse supply chains. The conceptual framework presented in this report seeks to diminish the gap in literature and provide clothing retailers with KPIs with a focus on environmental sustainability that can help in the decision-making process. The framework is expected to promote sustainability as a more central decision-making criterion within reverse supply chains, especially within the apparel industry.
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| 16. |
- Akre, O, et al.
(författare)
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Similar at a glance, but not the same
- 2008
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Ingår i: International journal of cancer. - : Wiley. - 1097-0215 .- 0020-7136. ; 123:6, s. 1480-1480
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 17. |
- Alabbasi, Abdulrahman, et al.
(författare)
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Optimal Processing Allocation to Minimize Energy and Bandwidth Consumption in Hybrid CRAN
- 2018
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Ingår i: IEEE Transactions on Green Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2473-2400. ; 2:2, s. 545-555
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Tidskriftsartikel (refereegranskat)abstract
- Cloud radio access network (CRAN) architecture is proposed to save energy, facilitate coordination between radio units, and achieve scalable solutions to improve radio network's performance. However, stringent delay and bandwidth constraints are incurred by fronthaul in CRAN [the network segment connecting RUs and digital units (DUs)]. Therefore, we propose a hybrid cloud radio access network architecture, where a DU's functionalities can be virtualized and split at several conceivable points. Each split option results in two-level deployment of the processing functions (central site level and remote site level) connected by a transport network, called midhaul. We study the interplay of energy efficiency and midhaul bandwidth consumption under optimal processing allocation. We jointly minimize the power and midhaul bandwidth consumption in H-CRAN, while satisfying network constraints, i.e., processing and midhaul bandwidth capacity. We enable power saving functionalities by shutting down different network components. The proposed model is formulated as a constraint programming problem. The proposed solution shows that 42 percentile of midhaul bandwidth savings can be achieved compared to the fully centralized CRAN; and 35 percentile of power consumption saving can be achieved compared to the case where all the network functions are distributed at the edge.
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| 18. |
- Albinsson, Ingvar, 1962
(författare)
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Dielectric and Conductivity Studies of Polymer Electrolytes
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dielectric and conductivity studies has been performed in order to study the microscopic structure and dynamics of ion conducting polymers. The investigated systems are various salts, e.g. LiCF3SO3, dissolved in poly(ethylene glycol), poly(propylene glycol) or copolymers which partly consists of these polymers. The ionic conductivity has been measured over a wide range of concentrations. The results show similar behaviour to traditional liquid solvents featuring low permittivity. The dielectric measurements show a rapid increase in the static relative permittivity which may be attributed to the formation of ion pairs. The values of the static relative permittivity for the solution is used in a thermodynamic treatment for estimating the fractions of dissociated ions and ions associated into pairs, triplets, quadrupoles and hexapoles. The calculations show that the fraction of dissociated ions increases with increasing concentration of salt, if the static permittivity of the solution, and not the solvent is used. The dielectric measurements show also a dispersion at about 1 MHz for NH4CF3SO3, dissolved in poly(propylene glycol) at room temperature. It is argued that ion pairs should be the cause of this dielectric loss and that the corresponding frequency might serve as a probe for the local flexibility of the polymer chain segments. It may also be an alternative way to estimate the mobility of the charge carriers.
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| 19. |
- Albinsson, Ingvar, 1962, et al.
(författare)
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Intermediate temperature solid oxide fuel cells for solar energy systems
- 2005
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Ingår i: Proceedings of The 4th Sino-Swedish fuel cell workshop and joint Energy-Environment Forum. Ed. by . Zhu, B. , Mao, Z. , Mellander, B.-E. , Sundén, B. , Zhang, M.. ; , s. 69-
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Konferensbidrag (refereegranskat)
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| 20. |
- Ali Khan, Uzair, et al.
(författare)
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Risk of colorectal cancer in patients with diabetes mellitus : A Swedish nationwide cohort study
- 2020
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Ingår i: PLoS Medicine. - : Public Library of Science (PLoS). - 1549-1676. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Colorectal cancer (CRC) incidence is increasing among young adults below screening age, despite the effectiveness of screening in older populations. Individuals with diabetes mellitus are at increased risk of early-onset CRC. We aimed to determine how many years earlier than the general population patients with diabetes with/without family history of CRC reach the threshold risk at which CRC screening is recommended to the general population. METHODS AND FINDINGS: A nationwide cohort study (follow-up:1964-2015) involving all Swedish residents born after 1931 and their parents was carried out using record linkage of Swedish Population Register, Cancer Registry, National Patient Register, and Multi-Generation Register. Of 12,614,256 individuals who were followed between 1964 and 2015 (51% men; age range at baseline 0-107 years), 162,226 developed CRC, and 559,375 developed diabetes. Age-specific 10-year cumulative risk curves were used to draw conclusions about how many years earlier patients with diabetes reach the 10-year cumulative risks of CRC in 50-year-old men and women (most common age of first screening), which were 0.44% and 0.41%, respectively. Diabetic patients attained the screening level of CRC risk earlier than the general Swedish population. Men with diabetes reached 0.44% risk at age 45 (5 years earlier than the recommended age of screening). In women with diabetes, the risk advancement was 4 years. Risk was more pronounced for those with additional family history of CRC (12-21 years earlier depending on sex and benchmark starting age of screening). The study limitations include lack of detailed information on diabetes type, lifestyle factors, and colonoscopy data. CONCLUSIONS: Using high-quality registers, this study is, to our knowledge, the first one that provides novel evidence-based information for risk-adapted starting ages of CRC screening for patients with diabetes, who are at higher risk of early-onset CRC than the general population.
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