| 1. |
- Katselis, Dimitrios
(författare)
-
Some Preamble Design Aspects in CP-OFDM Systems
- 2012
-
Ingår i: IEEE Communications Letters. - 1089-7798 .- 1558-2558. ; 16:3, s. 356-359
-
Tidskriftsartikel (refereegranskat)abstract
- A fundamental problem in training-based channel estimation for various communication systems is the preamble design. Two crucial aspects in such a design are the achievable mean square error (MSE) and the corresponding peak-to-average power ratio (PAPR). In this letter, preamble-based least squares (LS) channel estimation in CP-OFDM systems is considered. Ignoring the PAPR aspect, several MSE-optimal preambles and a necessary condition for their existence are presented. To this end, a training energy constraint, containing also the energy spent to the cyclic prefix (CP), is imposed. This constraint differs from the usual training energy constraints in the existing literature, which ignore the CP energy during training. These preambles contribute in the completion of existing results concerning MSE-optimal preambles in CP-OFDM systems. However, since high PAPR is an issue concerning these optimal designs, we show how these MSE-optimal preambles can be combined with the usual Zadoff-Chu (ZC) sequences to enlarge the class of PAPR-optimal preambles that achieve good MSE performance at the same time.
|
|
| 2. |
- Arce, P., et al.
(författare)
-
Report on G4-Med, a Geant4 benchmarking system for medical physics applications developed by the Geant4 Medical Simulation Benchmarking Group
- 2021
-
Ingår i: Medical Physics. - : Wiley. - 0094-2405 .- 2473-4209. ; 48:1, s. 19-56
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Geant4 is a Monte Carlo code extensively used in medical physics for a wide range of applications, such as dosimetry, micro- and nanodosimetry, imaging, radiation protection, and nuclear medicine. Geant4 is continuously evolving, so it is crucial to have a system that benchmarks this Monte Carlo code for medical physics against reference data and to perform regression testing. Aims: To respond to these needs, we developed G4-Med, a benchmarking and regression testing system of Geant4 for medical physics. Materials and Methods: G4-Med currently includes 18 tests. They range from the benchmarking of fundamental physics quantities to the testing of Monte Carlo simulation setups typical of medical physics applications. Both electromagnetic and hadronic physics processes and models within the prebuilt Geant4 physics lists are tested. The tests included in G4-Med are executed on the CERN computing infrastructure via the use of the geant-val web application, developed at CERN for Geant4 testing. The physical observables can be compared to reference data for benchmarking and to results of previous Geant4 versions for regression testing purposes. Results: This paper describes the tests included in G4-Med and shows the results derived from the benchmarking of Geant4 10.5 against reference data. Discussion: Our results indicate that the Geant4 electromagnetic physics constructor G4EmStandardPhysics_option4 gives a good agreement with the reference data for all the tests. The QGSP_BIC_HP physics list provided an overall adequate description of the physics involved in hadron therapy, including proton and carbon ion therapy. New tests should be included in the next stage of the project to extend the benchmarking to other physical quantities and application scenarios of interest for medical physics. Conclusion: The results presented and discussed in this paper will aid users in tailoring physics lists to their particular application.
|
|
| 3. |
|
|
| 4. |
- Zagal, Jose, et al.
(författare)
-
Dark Patterns in the Design of Games
- 2013
-
Ingår i: Foundations of Digtal Games 2013.
-
Konferensbidrag (refereegranskat)abstract
- Game designers are typically regarded as advocates for players. However, a game creator’s interests may not align with the players’. We examine some of the ways in which those opposed interests can manifest in a game’s design. In particular, we examine those elements of a game’s design whose purpose can be argued as questionable and perhaps even unethical. Building upon earlier work in design patterns, we call these abstracted elements Dark Game Design Patterns. In this paper, we develop the concept of dark design patterns in games, present examples of such patterns, explore some of the subtleties involved in identifying them, and provide questions that can be asked to help guide in the specification and identification of future Dark Patterns. Our goal is not to criticize creators but rather to contribute to an ongoing discussion regarding the values in games and the role that designers and creators have in this process.
|
|
| 5. |
|
|
| 6. |
- Drevenhorn, Eva, et al.
(författare)
-
Blood pressure measurement--an observational study of 21 public health nurses
- 2001
-
Ingår i: Journal of Clinical Nursing. - : Wiley. - 1365-2702 .- 0962-1067. ; 10:2, s. 189-194
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to observe how public health nurses perform blood pressure measurement. Structured observations were made of 21 randomly selected public health nurses while they performed three blood pressure measurements. The public health nurses used an overall correct method for blood pressure measurement. Five nurses out of 21 used the Tri-cuff but the soft cuff was most frequently used. When choosing the breadth of the cuff, 10 nurses decided by eye and not by the marks on the cuff. To ensure a completely correct method additional information is needed by nurses.
|
|
| 7. |
|
|
| 8. |
- Janelidze, Shorena, et al.
(författare)
-
Associations of Plasma Phospho-Tau217 Levels with Tau Positron Emission Tomography in Early Alzheimer Disease
- 2021
-
Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149. ; 78:2, s. 149-149
-
Tidskriftsartikel (refereegranskat)abstract
- Importance: There is an urgent need for inexpensive and minimally invasive blood biomarkers for Alzheimer disease (AD) that could be used to detect early disease changes. Objective: To assess how early in the course of AD plasma levels of tau phosphorylated at threonine 217 (P-tau217) start to change compared with levels of established cerebrospinal fluid (CSF) and positron emission tomography (PET) biomarkers of AD pathology. Design, Setting, and Participants: This cohort study included cognitively healthy control individuals (n = 225) and participants with subjective cognitive decline (n = 89) or mild cognitive impairment (n = 176) from the BioFINDER-2 study. Participants were enrolled at 2 different hospitals in Sweden from January 2017 to October 2019. All study participants underwent plasma P-tau217 assessments and tau- and amyloid-β (Aβ)-PET imaging. A subcohort of 111 participants had 2 or 3 tau-PET scans. Main Outcomes and Measures: Changes in plasma P-tau217 levels in preclinical and prodromal AD compared with changes in CSF P-tau217 and PET measures. Results: Of 490 participants, 251 were women (51.2%) and the mean (SD) age was 65.9 (13.1) years. Plasma P-tau217 levels were increased in cognitively unimpaired participants with abnormal Aβ-PET but normal tau-PET in the entorhinal cortex (Aβ-PET+/ tau-PET- group vs Aβ-PET-/ tau-PET- group: median, 2.2 pg/mL [interquartile range (IQR), 1.5-2.9 pg/mL] vs 0.7 pg/mL [IQR, 0.3-1.4 pg/mL]). Most cognitively unimpaired participants who were discordant for plasma P-tau217 and tau-PET were positive for plasma P-tau217 and negative for tau-PET (P-tau217+/tau-PET-: 36 [94.7%]; P-tau217-/tau-PET+: 2 [5.3%]). Event-based modeling of cross-sectional data predicted that in cognitively unimpaired participants and in those with mild cognitive impairment, both plasma and CSF P-tau217 would change before the tau-PET signal in the entorhinal cortex, followed by more widespread cortical tau-PET changes. When testing the association with global Aβ load in nonlinear spline models, both plasma and CSF P-tau217 were increased at lower Aβ-PET values compared with tau-PET measures. Among participants with normal baseline tau-PET, the rates of longitudinal increase in tau-PET in the entorhinal cortex were higher in those with abnormal plasma P-tau217 at baseline (median standardized uptake value ratio, 0.029 [IQR, -0.006 to 0.041] vs -0.001 [IQR, -0.021 to 0.020]; Mann-Whitney U, P =.02). Conclusions and Relevance: In this cohort study, plasma P-tau217 levels were increased during the early preclinical stages of AD when insoluble tau aggregates were not yet detectable by tau-PET. Plasma P-tau217 may hold promise as a biomarker for early AD brain pathology.
|
|
| 9. |
|
|
| 10. |
- Thomas, Alexander
(författare)
-
Home in hardship : Exploring how United Nations professionals negotiate constructions of home in and between hardship settings.
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- There is a general recognition within the social sciences that extensive mobility challenges how we perceive the notion of home. With this idea as its starting point, this article explores how situations of hardship impact the ways in which mobile professionals negotiate and construct their homes. The actor-network theory (ANT) has been used as the means to explore the interactions between the people who inform this study and the multidimensional characteristics of the hardship setting. Through individual, open-ended interviews, the research draws upon the experiences of five international civil servants from the United Nations (UN) system of organizations who are assigned to hardship duty stations. Applying ANT to the empirical material drew the attention to the identification of five principal entities (or actors) that come into play in the negotiation of homeconstruction, namely the civil servant, [in]security, mobility, ownership and social relations. The influence of the various nonhuman actors on home construction varied according to the individual and their transnational ties and professional status – those with family nuclei tended to situate their homes in terms of territoriality, whereas for others, factors such as privacy, materiality and social interaction weighed more heavily in the act of creating home.
|
|
