| 1. |
- Lee, Marcus, et al.
(author)
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Low-latitude zooplankton pigmentation plasticity in response to multiple threats
- 2019
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In: Royal Society Open Science. - : Royal Society Open Science. - 2054-5703. ; 6:7, s. 1-10
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Journal article (peer-reviewed)abstract
- Crustacean copepods in high-latitude lakes frequently alter their pigmentation facultatively to defend themselves against prevailing threats, such as solar ultraviolet radiation ( UVR) and visually oriented predators. Strong seasonality in those environments promotes phenotypic plasticity. To date, no one has investigated whether low-latitude copepods, experiencing continuous stress from UVR and predation threats, exhibit similar inducible defences. We here investigated the pigmentation levels of Bahamian 'blue hole' copepods, addressing this deficit. Examining several populations varying in predation risk, we found the lowest levels of pigmentation in the population experiencing the highest predation pressure. In a laboratory experiment, we found that, in contrast with our predictions, copepods from these relatively constant environments did show some changes in pigmentation subsequent to the removal of UVR; however, exposure to water from different predation regimes induced minor and idiosyncratic pigmentation change. Our findings suggest that low-latitude zooplankton in inland environments may exhibit reduced, but non-zero, levels of phenotypic plasticity compared with their high-latitude counterparts.
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| 2. |
- Weinberg-Krakowski, Susanne, 1955-, et al.
(author)
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The Effect of Quarterly Reporting on Companies Financial Performance : A Survey Study on Five Nordic Stock Markets
- 2018
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Conference paper (other academic/artistic)abstract
- Early version. May not be quoted.Extended Abstract: In this paper, we study what effect the quarterly reporting has on the reporting company’s financial performance. This question is of current interest in the light of the European Commission 2013 amending its Transparency Directive, where the Commission abolishes the requirement for quarterly reports by publicly traded companies. The survey was performed on the five Nordic stock markets where 157 Chief Financial Officers (CFOs) of listed companies out of 711 responded (response rate of 22 percent). This study is based on the results of the questionnaire sent out to the CFOs of all companies listed on the OMX Nordic Stock Exchange in December 2007. In May 2008, a questionnaire was also sent out to the CFOs of companies listed on the Oslo Stock Exchange. The OMX Nasdaq questionnaire was sent as a letter addressed to a named CFO, where the CFO received a cover letter from the CEO Jukka Ruuska of OMX.The questionnaire included six pages of questions for the CFOs. In terms of quarterly reporting, the respondents were asked to respond to six questions. Three were yes or no questions and three were specific questions concerning quarterly reporting where the CFOs were asked to give her/his perception of the use of the quarterly reporting on a scale from 1 (strongly disagree) to 5 (strongly agree).Respondents were asked to indicate (yes or no) whether the company’s performance was affected by the quarterly reporting. The results show that 83 percent of the Icelandic CFOs answered that the quarterly reports affect company performance, while the corresponding figure was 79 percent for Norway, 67 percent for Finland, 44 percent for Sweden, and 41 percent for Danish companies. The main perceived effect the quarterly reporting has on company’s performance is that it creates short-term pressure (3.77 out of 5). The main positive opinion of the quarterly reports is that they give the company a tool to communication with the capital market (4.2 out of 5), but also that the reports make the company focus on cash flow (3.0 out of 5). The CFOs indicate that the quarterly reports require too much effort compared to benefits realized (2.95 out of 5). Furthermore, the responding CFOs indicate that quarterly reporting makes the company consider timeliness of acquisitions, divestments, and investments (2.91 out of 5), obscures the company’s operational goals (2.73), and makes the company emphasize incoming orders (2.64).The results indicate that more than half of the companies have their quarterly and semi-annual reports audited by their external auditors. Almost 60 percent of these companies also say that the reports affect the way the company performs.We performed a t-test to reveal if there is a difference between the companies where the CFO believes that quarterly reporting affects the company’s performance and the CFOs that do not believe that quarterly reporting affects the company’s performance. Here we find a significant difference between CFOs that believe that quarterly reporting affects company performance in that these companies have higher volatility, lower current ratio and that the CFOs perceive higher general short-term pressure.Further, we performed multiple regressions to test whether perceiving an effect from quarterly reporting also has an effect on a CFO’s ability to accurately forecast future sales. The companies’ performance is measured as forecast accuracy (i.e. the difference between forecasted turnover growth for five years and the actual growth). Here we found that quarterly reporting has a significant negative effect on forecast accuracy.Our study contributes to the current literature in several ways. First, we have a wide set of explanatory variables to explain cross sectional differences, including data from all Nordic countries, which enables us to determine if differences are driven by company heterogeneity. Second, the responses were matched with background information regarding firm- and CFO specific data, financials, ownership type etc. This allows us to examine whether the assumptions behind the theories are valid.
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| 3. |
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| 4. |
- Satpute, Sumeet, 1987-, et al.
(author)
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Concurrent co-location maneuver planning for geostationary satellites
- 2019
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In: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 163:Part B, s. 211-224
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Journal article (peer-reviewed)abstract
- This paper details the development of a planning algorithm for multiple co-located geostationary satellites to perform station keeping and momentum unloading maneuvers concurrently. The objective is to minimize the overall fuel consumption while guaranteeing a safe separation distance between the satellites within a specific geostationary slot, as well as managing their stored angular momentum to maintain their nadir pointing orientation. The algorithm adopts the leader-follower architecture to define relative orbital elements of the satellites equipped with four gimbaled on-off electric thrusters, and solves a convex optimization problem with inequality constraints, including momentum unloading requirements, to determine the optimal maneuvers. The proposed algorithm is verified, in terms of fuel consumption, constraints enforcement and satellites performance, using numerical simulations that take into account dominant perturbations in the geostationary environment.
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| 5. |
- Fu, Jingru, et al.
(author)
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Fast three-dimensional image generation for healthy brain aging using diffeomorphic registration
- 2023
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In: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 44:4, s. 1289-1308
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Journal article (peer-reviewed)abstract
- Predicting brain aging can help in the early detection and prognosis of neurodegenerative diseases. Longitudinal cohorts of healthy subjects scanned through magnetic resonance imaging (MRI) have been essential to understand the structural brain changes due to aging. However, these cohorts suffer from missing data due to logistic issues in the recruitment of subjects. This paper proposes a methodology for filling up missing data in longitudinal cohorts with anatomically plausible images that capture the subject-specific aging process. The proposed methodology is developed within the framework of diffeomorphic registration. First, two novel modules are introduced within Synthmorph, a fast, state-of-the-art deep learning-based diffeomorphic registration method, to simulate the aging process between the first and last available MRI scan for each subject in three-dimensional (3D). The use of image registration also makes the generated images plausible by construction. Second, we used six image similarity measurements to rearrange the generated images to the specific age range. Finally, we estimated the age of every generated image by using the assumption of linear brain decay in healthy subjects. The methodology was evaluated on 2662 T1-weighted MRI scans from 796 healthy participants from 3 different longitudinal cohorts: Alzheimer's Disease Neuroimaging Initiative, Open Access Series of Imaging Studies-3, and Group of Neuropsychological Studies of the Canary Islands (GENIC). In total, we generated 7548 images to simulate the access of a scan per subject every 6 months in these cohorts. We evaluated the quality of the synthetic images using six quantitative measurements and a qualitative assessment by an experienced neuroradiologist with state-of-the-art results. The assumption of linear brain decay was accurate in these cohorts (R2 ∈ [.924,.940]). The experimental results show that the proposed methodology can produce anatomically plausible aging predictions that can be used to enhance longitudinal datasets. Compared to deep learning-based generative methods, diffeomorphic registration is more likely to preserve the anatomy of the different structures of the brain, which makes it more appropriate for its use in clinical applications. The proposed methodology is able to efficiently simulate anatomically plausible 3D MRI scans of brain aging of healthy subjects from two images scanned at two different time points.
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| 6. |
- De Rosa, G., et al.
(author)
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Velocity-resolved Reverberation Mapping of Five Bright Seyfert 1 Galaxies
- 2018
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 866:2
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Journal article (peer-reviewed)abstract
- We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one active galactic nucleus (AGN) (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-H beta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure H beta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity-dependent H beta lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
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| 7. |
- Gribbe, Johan, 1979-
(author)
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LEO: Databehandling och operativ ledning inom försvaret, 1972-89 : Transkript av ett vittnesseminarium vid Högkvarteret i Stockholm den 15 januari 2008
- 2008
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Reports (other academic/artistic)abstract
- The witness seminar ”LEO: Computing and Operational Command in the Swedish Armed Forces, 1972–89” was held at the Armed Forces Headquarter in Stockholm on 15 January 2008 and was led by Göran Tode. During the seminar, the development of the computerized command system LEO was discussed. After a major reorganisation of command structure in the late 1960s, the defence staff decided to develop a computerized command system to help central and regional headquarters conduct wartime operations. Each headquarter was to have one terminal system, with a number of work stations, containing information about all aspects of the battlefield. Information about friendly and enemy forces, fuel and ammunition supplies was to be stored in a central data base and a secure messaging system was to provide fast and reliable communications. Additional applications were developed to handle computations and simulations of transports and mobilization. Different aspects of this development were discussed at the seminar. Limitations in computer graphics and presentation technology was observed as a major technological problem in the early phase of the project. Other problems brought up concerned the considerable passive resistence from users and senior commanders, when new computer technology was introduced in old organizational structures. In addition to this, security started to emerge as a critical problem in the early 1980s when highly classified information about war plans, communications and intelligence were concentrated into a single computer system. Measures to control access of information in the system and to guarantee electronic security were discussed and debated. Moreover, the decision in 1979 to purchase mainframe computers from Norsk Data was covered at the seminar. The development of tools and methodology for COBOL programming was mentioned. Finally, the implementation of the system in central and regional staff headquarters in the late 1980s was also discussed.
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| 8. |
- Mahfuz, Istiak, et al.
(author)
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RNA interference and its role in the inhibition and cure of HIV/AIDS
- 2010
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In: Journal of Life and Earth Science. - : Rajshahi University. - 1990-4827 .- 2408-8641. ; 5, s. 1-10
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Journal article (peer-reviewed)abstract
- The HIV/AIDS epidemic kills about 2.1 million people around the world every year. Unfortunately, until now attempts to control and diminish further spread of the disorder have resulted in very limited success. Although highly active antiretroviral therapy (HAART) is now available as a treatment option, the rate of its success is limited because of drug resistance. In this context, a more efficient treatment is very much necessary to fight with this fatal disease. The RNA interference (RNAi) can be employed as one of the powerful methods for treatment of the disease as it can effectively silence gene expression in a sequence specific manner. The RNAi-mediated treatment is therefore a promising substitution for therapy of the global epidemic HIV/AIDS in the future. The main objective of this review is to focus on an in-depth analysis of RNAi and the principles underlying RNAi treatment, and it's also described the molecular mechanisms of HIV infection, current treatment facilities available to patients as well as therapeutic applications of RNAi along with their limitations as to why the options are inadequate to give a safe and sound cure of HIV/AIDS.
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| 9. |
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| 10. |
- Wang, Rui, et al.
(author)
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MRI load of cerebral microvascular lesions and neurodegeneration, cognitive decline, and dementia
- 2018
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In: Neurology. - 0028-3878 .- 1526-632X. ; 91:16, s. 1487-1497
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Journal article (peer-reviewed)abstract
- Objective To explore the differential associations of neurodegeneration and microvascular lesion load with cognitive decline and dementia in older people and the modifying effect of the APOE genotype on these associations. Methods A sample of 436 participants (age >= 60 years) was derived from the population-based Swedish National study on Aging and Care in Kungsholmen, Stockholm, and clinically examined at baseline (2001-2003) and 3 occasions during the 9-year follow-up. At baseline, we assessed microvascular lesion load using a summary score for MRI markers of lacunes, white matter hyperintensities (WMHs), and perivascular spaces and neurodegeneration load for markers of enlarged ventricles, smaller hippocampus, and smaller gray matter. We assessed cognitive function using the Mini-Mental State Examination (MMSE) test and diagnosed dementia following the Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria. We analyzed data using linear mixed-effects, mediation, and random-effects Cox models. Results During the follow-up, 46 participants were diagnosed with dementia. Per 1-point increase in microvascular lesion and neurodegeneration score (range 0-3) was associated with multiple adjusted beta-coefficients of -0.35 (95% confidence interval, -0.51 to -0.20) and -0.44 (-0.56 to -0.32), respectively, for the MMSE score and multiple adjusted hazard ratios of 1.68 (1.12-2.51) and 2.35 (1.58-3.52), respectively, for dementia; carrying APOE epsilon 4 reinforced the associations with MMSE decline. WMH volume changes during the follow-up mediated 66.9% and 12.7% of the total association of MMSE decline with the baseline microvascular score and neurodegeneration score, respectively. Conclusions Both cerebral microvascular lesion and neurodegeneration loads are strongly associated with cognitive decline and dementia. The cognitive decline due to microvascular lesions is exacerbated by APOE epsilon 4 and is largely attributed to progression and development of microvascular lesions.
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