| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Chatzidiamantis, N. D., et al.
(författare)
-
Inverse Gaussian Modeling of Turbulence-Induced Fading in Free-Space Optical Systems
- 2011
-
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 29:10, s. 1590-1596
-
Tidskriftsartikel (refereegranskat)abstract
- We propose the inverse Gaussian distribution, as a less complex alternative to the classical log-normal model, to describe turbulence-induced fading in free-space optical (FSO) systems operating in weak turbulence conditions and/or in the presence of aperture averaging effects. By conducting goodness of fit tests, we define the range of values of the scintillation index for various multiple-input multiple-output (MIMO) FSO configurations, where the two distributions approximate each other with a certain significance level. Furthermore, the bit error rate performance of two typical MIMO FSO systems is investigated over the new turbulence model; an intensity-modulation/direct detection MIMO FSO system with Q-ary pulse position modulation that employs repetition coding at the transmitter and equal gain combining at the receiver, and a heterodyne MIMO FSO system with differential phase-shift keying and maximal ratio combining at the receiver. Finally, numerical results are presented that validate the theoretical analysis and provide useful insights into the implications of the model parameters on the overall system performance.
|
|
| 5. |
- Matthaiou, Michail, 1981, et al.
(författare)
-
Analytic Framework for the Effective Rate of MISO Fading Channels
- 2012
-
Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 60:6, s. 1741-1751
-
Tidskriftsartikel (refereegranskat)abstract
- The delay constraints imposed by future wireless applications require a suitable metric for assessing their impact on the overall system performance. Since the classical Shannon's ergodic capacity fails to do so, the so-called effective rate was recently established as a rigorous alternative. While prior relevant works have improved our knowledge on the effective rate characterization of communication systems, an analytical framework encompassing several fading models of interest is not yet available. In this paper, we pursue a detailed effective rate analysis of Nakagami-m, Rician and generalized-K multiple-input single-output (MISO) fading channels by deriving new, analytical expressions for their exact effective rate. Moreover, we consider the asymptotically low and high signal-to-noise regimes, for which tractable, closed-form effective rate expressions are presented. These results enable us to draw useful conclusions about the impact of system parameters on the effective rate of different MISO fading channels. All the theoretical expressions are validated via Monte-Carlo simulations.
|
|
| 6. |
- Ordóñez-Mena, José Manuel, et al.
(författare)
-
Quantification of the smoking-associated cancer risk with rate advancement periods : meta-analysis of individual participant data from cohorts of the CHANCES consortium
- 2016
-
Ingår i: BMC Medicine. - : Springer Science and Business Media LLC. - 1741-7015. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Smoking is the most important individual risk factor for many cancer sites but its association with breast and prostate cancer is not entirely clear. Rate advancement periods (RAPs) may enhance communication of smoking related risk to the general population. Thus, we estimated RAPs for the association of smoking exposure (smoking status, time since smoking cessation, smoking intensity, and duration) with total and site-specific (lung, breast, colorectal, prostate, gastric, head and neck, and pancreatic) cancer incidence and mortality.Methods: This is a meta-analysis of 19 population-based prospective cohort studies with individual participant data for 897,021 European and American adults. For each cohort we calculated hazard ratios (HRs) for the association of smoking exposure with cancer outcomes using Cox regression adjusted for a common set of the most important potential confounding variables. RAPs (in years) were calculated as the ratio of the logarithms of the HRs for a given smoking exposure variable and age. Meta-analyses were employed to summarize cohort-specific HRs and RAPs.Results: Overall, 140,205 subjects had a first incident cancer, and 53,164 died from cancer, during an average follow-up of 12 years. Current smoking advanced the overall risk of developing and dying from cancer by eight and ten years, respectively, compared with never smokers. The greatest advancements in cancer risk and mortality were seen for lung cancer and the least for breast cancer. Smoking cessation was statistically significantly associated with delays in the risk of cancer development and mortality compared with continued smoking.Conclusions: This investigation shows that smoking, even among older adults, considerably advances, and cessation delays, the risk of developing and dying from cancer. These findings may be helpful in more effectively communicating the harmful effects of smoking and the beneficial effect of smoking cessation.
|
|
| 7. |
- Papalampros, Alexandros, et al.
(författare)
-
Unique Spatial Immune Profiling in Pancreatic Ductal Adenocarcinoma with Enrichment of Exhausted and Senescent T Cells and Diffused CD47-SIRP proportional to Expression
- 2020
-
Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 12:7
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Pancreatic ductal adenocarcinoma (PDAC) is resistant to single-agent immunotherapies. To understand the mechanisms leading to the poor response to this treatment, a better understanding of the PDAC immune landscape is required. The present work aims to study the immune profile in PDAC in relationship to spatial heterogeneity of the tissue microenvironment (TME) in intact tissues. Methods: Serial section and multiplex in situ analysis were performed in 42 PDAC samples to assess gene and protein expression at single-cell resolution in the: (a) tumor center (TC), (b) invasive front (IF), (c) normal parenchyma adjacent to the tumor, and (d) tumor positive and negative draining lymph nodes (LNs). Results: We observed: (a) enrichment of T cell subpopulations with exhausted and senescent phenotype in the TC, IF and tumor positive LNs; (b) a dominant type 2 immune response in the TME, which is more pronounced in the TC; (c) an emerging role of CD47-SIRP a axis; and (d) a similar immune cell topography independently of the neoadjuvant chemotherapy. Conclusion: This study reveals the existence of dysfunctional T lymphocytes with specific spatial distribution, thus opening a new dimension both conceptually and mechanistically in tumor-stroma interaction in PDAC with potential impact on the efficacy of immune-regulatory therapeutic modalities.
|
|
| 8. |
- Athanasakis-Kaklamanakisa, Michail, et al.
(författare)
-
Voltage scanning and technical upgrades at the Collinear Resonance Ionization Spectroscopy experiment
- 2023
-
Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS. - 0168-583X .- 1872-9584. ; 541, s. 86-89
-
Tidskriftsartikel (refereegranskat)abstract
- To optimize the performance of the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at CERN-ISOLDE, technical upgrades are continuously introduced, aiming to enhance its sensitivity, precision, stability, and efficiency. Recently, a voltage-scanning setup was developed and commissioned at CRIS, which improved the scanning speed by a factor of three as compared to the current laser-frequency scanning approach. This leads to faster measurements of the hyperfine structure for systems with high yields (more than a few thousand ions per second). Additionally, several beamline sections have been redesigned and manufactured, including a new field-ionization unit, an electrostatic bend with a larger deflection angle, and improved ion optics. The beamline upgrades are expected to yield an improvement of at least a factor of 5 in the signal-to-noise ratio by avoiding the use of high-power lasers (which yield non-resonantly produced ions) and providing time-of-flight separation between the resonant ions and the collisional background.
|
|
| 9. |
- Björnson, Emil, et al.
(författare)
-
DISTRIBUTED MASSIVE MIMO IN CELLULAR NETWORKS: IMPACT OF IMPERFECT HARDWARE AND NUMBER OF OSCILLATORS
- 2015
-
Ingår i: 2015 23rd European Signal Processing Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 2076-1465. - 9780992862633 ; , s. 2436-2440
-
Konferensbidrag (refereegranskat)abstract
- Distributed massive multiple-input multiple-output (MIMO) combines the array gain of coherent MIMO processing with the proximity gains of distributed antenna setups. In this paper, we analyze how transceiver hardware impairments affect the downlink with maximum ratio transmission. We derive closed-form spectral efficiencies expressions and study their asymptotic behavior as the number of the antennas increases. We prove a scaling law on the hardware quality, which reveals that massive MIMO is resilient to additive distortions, while multiplicative phase noise is a limiting factor. It is also better to have separate oscillators at each antenna than one per BS.
|
|
| 10. |
|
|
