| 1. |
- Aad, G., et al.
(author)
-
- 2013
-
In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 110:2
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Journal article (peer-reviewed)
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| 2. |
- Jansen, Marc, 1976-, et al.
(author)
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A Complementary View for Better Understanding the Term Computational Thinking
- 2018
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In: Proceedings of the International Conference on Computational Thinking Education 2018. - Hong Kong : The Education University of Hong Kong. - 9789887703457 ; , s. 2-7
-
Conference paper (peer-reviewed)abstract
- The term Computational Thinking is closely related to efforts connected to teach a systematic and well-structured way of problem solving that includes a set of tools and techniques used in Computer Science. While substantial research in this field has shown promising outcomes concerning distinct intervention programs and teaching initiatives, the term Computational Thinking itself requires to be revised in order to get a wider consensus about its meaning and purpose. This paper contributes to the ongoing quest concerning the definition of the term by starting with a fundamental perspective on computational theory and corresponding concepts in order to describe the theoretical building blocks of a systematic view to further elaborate on an approach for teaching and learning about Computational Thinking. Additionally, based on this foundational effort, more advanced concepts are presented and discussed in order to better understand this domain. Finally, the paper identifies and discusses a set of relevant challenges taking a cognitive psychology perspective on Computational Thinking.
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| 3. |
- Sabiniarz, Patrik, 1979, et al.
(author)
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A waveguide finite element aided analysis of the wave field on a stationary tyre, not in contact with the ground
- 2010
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In: Journal of Sound and Vibration. - : Elsevier BV. - 1095-8568 .- 0022-460X. ; 329:15, s. 3041-3064
-
Journal article (peer-reviewed)abstract
- Although tyre/road noise has been a research subject for more than three decades, there is still no consensus in the literature as to which waves on a tyre are mainly responsible for the radiation of sound during rolling. Even the free vibrational behaviour of a stationary (non-rotating) tyre, not in contact with the ground, is still not well understood in the mid- and high-frequency ranges. Thus, gaining an improved understanding of this behaviour is a natural first step towards illuminating the question of which waves on a rolling tyre contribute to sound radiation. This is the topic of the present paper, in which a model based on the waveguide finite element method (WFEM) is used to study free wave propagation, on a stationary tyre, in the range 0-1500 Hz. In the low-frequency region (0-300 Hz), wave propagation is found to be rather straightforward, with two main wave-types present. Both have cross-section modes involving a nearly rigid motion of the belt. For higher frequencies (300-1500 Hz) the behaviour is more complex, including phenomena such as 'curve veering' and waves for which the phase speed and group speed have opposite signs. Wave-types identified in this region include (i) waves involving mainly sidewall deformation, (ii) belt bending waves, (iii) a wave with significant extensional deformation of the central belt region and (iv) a wave with a 'breathing' cross-section mode. The phase speed corresponding to found waves is computed and their radiation efficiency is discussed, assuming free-field conditions. In a future publication, the tyre model will be used in conjunction with a contact model and a radiation model to investigate the contribution of these waves to radiated sound during rolling. (C) 2010 Elsevier Ltd. All rights reserved.
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| 4. |
- Jansen, K, et al.
(author)
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Polynomial time approximation schemes for max-bisection on planar and geometric graphs
- 2005
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In: SIAM Journal on Computing. - 0097-5397. ; 35:1, s. 110-119
-
Journal article (other academic/artistic)abstract
- The max-bisection and min-bisection problems are to find a partition of the vertices of a graph into two equal size subsets that, respectively, maximizes or minimizes the number of edges with endpoints in both subsets. We design the first polynomial time approximation scheme for the max-bisection problem on arbitrary planar graphs solving a long-standing open problem. The method of solution involves designing exact polynomial time algorithms for computing optimal partitions of bounded treewidth graphs, in particular max- and min-bisection, which could be of independent interest. Using a similar method we design also the first polynomial time approximation scheme for max-bisection on unit disk graphs ( which could also be easily extended to other geometrically defined graphs).
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| 5. |
- Krege, Susanne, et al.
(author)
-
European consensus conference on diagnosis and treatment of germ cell cancer: A report of the second meeting of the European Germ Cell Cancer Consensus Group (EGCCCG): Part II
- 2008
-
In: European Urology. - : Elsevier BV. - 1873-7560 .- 0302-2838. ; 53:3, s. 497-513
-
Research review (peer-reviewed)abstract
- Objectives: The first consensus report that had been presented by the European Germ Cell Cancer Consensus Group (EGCCCG) in 2004 has found widespread approval by many colleagues throughout the world. In November 2006, the group met a second time under the auspices of the Department of Urology of the Amsterdam Medical Center, The Netherlands. Methods: Medical oncologists, urologic surgeons, radiation oncologists as well as pathologists from several European countries reviewed and discussed the data that had emerged since the 2002 conference and incorporated the new data into updated and revised guidelines. As for the first meeting the methodology of evidence-based medicine (EBM) was applied. The results of the discussion were compiled by the writing committee. All participants have agreed to this final update. Results: The second part of the consensus paper includes the treatment of metastasised disease, residual tumour resection, salvage therapy, follow-up, and late toxicities. Conclusions: Whereas the vast majority of the recommendations made in 2004 remain valid 3 yr later, refinements in the treatment of early-stage as well as of advanced-stage testicular cancer have emerged from clinical trials. Despite technical improvements, expert clinical skills will continue to be one of the major determinants for the prognosis of patients with germ cell cancer. in addition, the particular needs of testicular cancer survivors have been acknowledged. (C) 2007 European Association of Urology. Published by Elsevier B.V. All rights reserved.
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| 6. |
- Bahaloohoreh, Hassan, 1983-
(author)
-
Experiments and simulations on the mechanics of ice and snow
- 2023
-
Licentiate thesis (other academic/artistic)abstract
- In this study, experiments and simulations were conducted to investigate ice and snow. The ice sintering force as a function of temperature, pressing force (contact load), contact duration, and particle size during the primary stage of sintering was formulated using experimental methods along with an approximate, semi-analytic, close-form solution. It was shown that the ice sintering force increases nearly linear with increasing external pressing force but best approximated as a power law for dependency on both contact duration and particle size. Moreover, the exponent of the power law for size dependence is around the value predicted by general sintering theory. The temperature dependence of the sintering force is highly nonlinear and follows the Arrhenius equation. It was observed that at temperatures closer to the melting point, a liquid bridge is observed upon these paration of the contacted ice particles. The ratio of ultimate tensile strength of ice to the axial stress concentration factor in tension is found as an important factor in determining the sintering force, and a value of nearly 1.1 MPa was estimated to best catch the sintering force of ice in different conditions. From the temperature dependency, the activation energy is calculated to be around 41.4 kJ/mol, which is close to the previously reported value. Also, the results for the sintering force suggest that smaller particles are “stickier” than larger particles. Moreover, cavitation and surface cracking is observed during the formation of the ice particles and these can be one of the sources for the variations observed in the measured ice sintering force values.The presence of a capillary bridge in contact between an ice particle and a "smooth" (or rough) Aluminum surface at relative humidity around 50% and temperatures below the melting point was experimentally demonstrated. Experiments were conducted under controlled temperature conditions and the mechanical instability of the bridge upon separation of the ice particle from the Aluminum surface with a constant speed was considered. It was observed that a liquid bridge with a more pronounced volume at temperatures near the melting point is formed. It was showen that the separation distance is proportional to the cube root of the volume of the bridge. The volume of the liquidbridge is used to estimate the thickness of the liquid layer on the ice particle and the estimated value was shown to be within the range reported in the literature. The thickness of the liquid layer decreases from nearly 56 nm at -1.7◦C to 0.2 nm at -12.7◦C. The dependence can be approximated with a power law, proportional to (TM − T)−β, where β < 2.6. We further observe that for a rough surface, the capillary bridge formation in the considered experimental conditions vanishes.The Discrete Element Method (DEM) was employed to simulate the filling behavior of dry snow. Snow as a heterogeneous, hot material which is constituted from spherical ice particles which can form bonds. The bonding behavior of ice particles is important in determining the macroscopic behavior of snow. The bond diameter of ice-ice contacts as a function of time, compressive load, and strain rate is used and a DEM for dry snow was developed and programmed in MATLAB. A beam element with implemented damage model was used in the simulation. The simulated parameters were macroscopic angle of repose, packing density, and surface conditions as a function of temperature and fillingrate. The DEM results were able to verify the existing published experimental data. The simulation results showed that angle of repose of snow decreased with decreasing the temperature, the surface became irregular due to particles rotation and re-arrangement for lower falling speeds of particles, and density increased with depth of deposition.
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| 7. |
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| 8. |
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| 9. |
- Jansen, Karl, 1966
(author)
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Network Modelling of Port Terminals Development of a Concept and a Tool
- 2001
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Doctoral thesis (other academic/artistic)abstract
- Network theory can be used to model and optimise logistic systems. The movement of goods is a major issue in our society and there is a large potential for increased efficiency in the transportation systems. Terminals and their equivalents are important in logistic systems. This is especially obvious when it comes to sea transport. The role of a port terminal is to collect goods on the landside before it can be loaded onto the ships and vice versa. A terminal is needed because of the large difference in the size between the vehicles feeding the ships and the ships themselves. If terminal operations can be improved the efficiency of the whole transportation system will be improved. The focus of this thesis is on the development and implementation of a tool for modelling port terminal operation. Results from the tool are the impact of infrastructural changes in the terminal and the impact of changing the routing of a cargo and resources through the terminal. Concepts and ideas behind the tool can also be used to model other terminals and transportation systems. The tool is based on networks. In a network the nodes play a very important role, because the flows are routed and rerouted there. All the flow changes in a system are made in the nodes. A modelling tool has to be based on strong theories and concepts. One such theory is combinatorial graph theory. This theory contains methods and algorithms for among other things handling flows on networks. Nodes with complex functionalities are, however, not handled very well by graph theory. There is a need for an extension of graph theory to include complex node functionalities to model logistic systems better. Part of this work is focused on the extension because it is needed for the development of the tool. The three problem areas addressed in the thesis are: The development and implementation of a tool for modelling port terminals based on an extended version of combinatorial graph theory. The extension of combinatorial graph theory to include complex node functionalities. The modelling of data and information associated with transportation.
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| 10. |
- Jansen, Karl, 1966, et al.
(author)
-
SEQUENCE DEPENDENCE OF 4',6-DIAMIDINO-2-PHENYLINDOLE (DAPI) DNA INTERACTIONS
- 1993
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 115:23, s. 10527-10530
-
Journal article (peer-reviewed)abstract
- We have characterized the interaction of 4',6-diamidino-2-phenylindole (DAPI) with a series of DNA oligonucleotides containing a varying number of contiguous alternating AT base pairs in the center of a GC-stretch. The binding affinity of DAPI to the oligonucleotides increases with the number of contiguous AT base pairs. When entropy effects are taken into account, the microscopic affinity reaches a maximum value when the oligonucleotides contain three AT base pairs. Three is also the minimum number of base pairs that provides a binding site with all the characteristics of binding observed with DNA and [poly(dA-dT)]2 at low binding ratios. With none or only a single AT base pair in the center of a GC dodecamer, the spectral properties of bound DAPI are very similar to those of DAPI bound to [poly(dG-dC)]2. When DAPI is complexed with an oligonucleotide containing two AT base pairs, the absorption and fluorescence properties of DAPI closely resemble those of DAPI complexed with [poly(dG-dC)]2, while the circular dichroism spectrum resembles that of DAPI bound to [poly(dA-dT)]2.
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| 11. |
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| 12. |
- Sabiniewicz, Agnieszka, et al.
(author)
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Olfactory-based interspecific recognition of human emotions: Horses (Equus ferus caballus) can recognize fear and happiness body odour from humans (Homo sapiens)
- 2020
-
In: Applied Animal Behaviour Science. - : ELSEVIER. - 0168-1591 .- 1872-9045. ; 230
-
Journal article (peer-reviewed)abstract
- Emotional recognition has been demonstrated to occur between members of different species. However, the majority of studies on interspecific communication of emotions so far focused on the senses of vision and hearing while the contribution of the sense of smell has rarely been studied in this context. Thus, the aim of our study was to assess if horses display differential behaviour in response to human fear and non-fear odour. Body odour samples were collected from 10 adult humans (Homo sapiens) in fear and happiness condition, respectively. The human body odour samples collected in these two conditions, together with a control condition, were then presented to a total of 21 horses (Equus ferus caballus). We found that the horses displayed some differential behaviour in response to human fear and non-fear odour. The horses lifted their heads significantly more frequently and for longer in the fear and in the control condition compared to the happiness condition. Similarly, the horses tended to touch a familiar person that was present during the test more frequently and for longer in the fear condition compared to the happiness condition. Additionally, depending on odour condition, the horses differed in the time they spent keeping their ears back. These results can be explained in the context of the process of domestication which may have favoured the development of the ability to recognize heterospecific emotions. To conclude, in the present study we provide evidence for a possible purely olfactory recognition of human emotions by horses.
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| 13. |
- Albert, Marie Christine, et al.
(author)
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Identification of FasL as a crucial host factor driving COVID-19 pathology and lethality
- 2024
-
In: Cell Death and Differentiation. - 1350-9047.
-
Journal article (peer-reviewed)abstract
- The dysregulated immune response and inflammation resulting in severe COVID-19 are still incompletely understood. Having recently determined that aberrant death-ligand-induced cell death can cause lethal inflammation, we hypothesized that this process might also cause or contribute to inflammatory disease and lung failure following SARS-CoV-2 infection. To test this hypothesis, we developed a novel mouse-adapted SARS-CoV-2 model (MA20) that recapitulates key pathological features of COVID-19. Concomitantly with occurrence of cell death and inflammation, FasL expression was significantly increased on inflammatory monocytic macrophages and NK cells in the lungs of MA20-infected mice. Importantly, therapeutic FasL inhibition markedly increased survival of both, young and old MA20-infected mice coincident with substantially reduced cell death and inflammation in their lungs. Intriguingly, FasL was also increased in the bronchoalveolar lavage fluid of critically-ill COVID-19 patients. Together, these results identify FasL as a crucial host factor driving the immuno-pathology that underlies COVID-19 severity and lethality, and imply that patients with severe COVID-19 may significantly benefit from therapeutic inhibition of FasL.
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| 14. |
- Buchecker, M., et al.
(author)
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The role of risk perception in making flood risk management more effective
- 2013
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In: Natural hazards and earth system sciences. - : Copernicus GmbH. - 1561-8633 .- 1684-9981. ; 13, s. 3013-3030
-
Journal article (peer-reviewed)abstract
- Over the last few decades, Europe has suffered from a number of severe flood events and, as a result, there has been a growing interest in probing alternative approaches to managing flood risk via prevention measures. A literature review reveals that, although in the last decades risk evaluation has been recognized as key element of risk management, and risk assessment methodologies (including risk analysis and evaluation) have been improved by including social, economic, cultural, historical and political conditions, the theoretical schemes are not yet applied in practice. One main reason for this shortcoming is that risk perception literature is mainly of universal and theoretical nature and cannot provide the necessary details to implement a comprehensive risk evaluation. This paper therefore aims to explore a procedure that allows the inclusion of stakeholders' perceptions of prevention measures in risk assessment. It proposes to adopt methods of risk communication (both one-way and two-way communication) in risk assessment with the final aim of making flood risk management more effective. The proposed procedure not only focuses on the effect of discursive risk communication on risk perception, and on achieving a shared assessment of the prevention alternatives, but also considers the effects of the communication process on perceived uncertainties, accepted risk levels, and trust in the managing institutions.The effectiveness of this combined procedure has been studied and illustrated using the example of the participatory flood prevention assessment process on the Sihl River in Zurich, Switzerland. The main findings of the case study suggest that the proposed procedure performed well, but that it needs some adaptations for it to be applicable in different contexts and to allow a (semi-) quantitative estimation of risk perception to be used as an indicator of adaptive capacity.
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| 15. |
- Çağatay, S., et al.
(author)
-
Transnational Spaces of Resistance
- 2022
-
In: Feminist and LGBTI+ Activism across Russia, Scandinavia and Turkey. - Cham : Palgrave Macmillan. - 2947-4361. - 9783030844509 ; , s. 49-82
-
Book chapter (other academic/artistic)abstract
- This chapter lays out the theoretical foundation of the book. It conceptualizes resistance as a space in-between small-scale mundane practices with a low level of collective organizing and large-scale protest activities which often exemplify resistance in social movement studies. In line with feminist and queer conceptualization of resistance, the authors suggest to examine multi-scalarity of resistant practices. The chapter attends to three scales of feminist and LGBTI+ activism in Russia, Turkey, and Scandinavia. The first scale analyzes activism in relation to the civil society-state-market triad. The second scale problematizes the notion of solidarity in relations between feminist and LGBTI+ activists from different geopolitical regions and countries as well as between small- and large-scale activist organizations and groups. Finally, the third scale focuses on individual resistant practices and the role of individual bodies in emergence of collective political struggles.
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| 16. |
- Krzyzanowska, Natalia, 1977-
(author)
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(Krytyczna) analiza dyskursu a (krytyczna) analiza gender : zarys synergii teoretycznej i metodologicznej[(Critical) discourse and (critical) gender analysis: towards a theoretical and methodological synergy]
- 2013
-
In: Przeglad Socjologii Jakosciowej. - Lodz, Poland : Lodz University, Faculty of Economics and Sociology, Institute of Sociology. - 1733-8069. ; 9:1, s. 62-84
-
Journal article (peer-reviewed)abstract
- This paper aims at highlighting the importance of (critical) discourse studies for contemporary social research. By looking closely at critical discourse analysis (CDA) as one of the leading paradigms within the critically-oriented discourse research, this work emphasises the importance of both theoretical and empirical impact of CDA on studies located within the paradigm of feminist gender studies. After pointing out diverse theoretical and methodological synergies between (critical) feminist gender- and discourse-research, the paper exemplifies these synergies by means of case study of the constructions of motherhood/fatherhood in the Polish public discourse. As the paper shows, such, and other, CDA-based theoretical and methodological synergies applied in practice might, in fact, be pivotal for the development of both academic reflections and social understandings of gender (and parent) roles in contemporary society.
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| 17. |
- Pernebo, Karin
(author)
-
Barn utsatta för våld i sin familj
- 2020
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In: Barn & unga i utsatta livssituationer. - Stockholm : Liber. - 9789147133598 ; , s. 103-122
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Book chapter (other academic/artistic)
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| 18. |
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| 19. |
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| 20. |
- Varna, Janis, et al.
(author)
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Non-linear behaviour of PLA based flax composites
- 2012
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In: Plastics, rubber and composites. - 1465-8011 .- 1743-2898. ; 41:2, s. 49-60
-
Journal article (peer-reviewed)abstract
- The mechanical behaviour of polylactic acid/flax fibre composite in tension was investigated by analysing elastic properties and loading curves. The observed non-linearity was attributed to microdamage, viscoelastic and viscoplastic response, suggesting Schapery's type of model for viscoelasticilty and Zapas' model for viscoplasticity. It was found that after loading at stress levels below the maximum possible, the elastic modulus is not affected, and therefore, damage does not need to be included in the material model. Viscoplastic and viscoelastic strain development was analysed in creep and strain recovery tests at several high stress levels. The identified and validated material model is non-linear viscoelastic and viscoplastic with slight non-linearity even in the elastic strain term. It appears that there is no region of linear viscoelasticity for this material. Non-linear elasticity, viscoelasticity and viscoplasticity are equally responsible for the observed non-linearity in the tensile tests
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| 21. |
- Amin, Awin, et al.
(author)
-
Patient-reported participation in hepatopancreatobiliary surgery cancer care : A pilot intervention study with patient-owned fast-track protocols
- 2022
-
In: European Journal of Cancer Care. - : Wiley. - 0961-5423 .- 1365-2354. ; 31:3
-
Journal article (peer-reviewed)abstract
- Objective Fast-track concepts have been implemented in hepatopancreatobiliary surgery cancer care to improve postoperative recovery. For optimal postoperative care, patient participation is also required. The aim was to investigate and analyse whether an intervention with patient-owned fast-track protocols (PFTPs) may lead to increased patient participation and improve information for patients who underwent surgery for hepatopancreatobiliary cancer. Methods A quantitative comparative design with a control and intervention group was used. The participants in the intervention group followed a PFTP during their admission. After discharge, the patients answered a questionnaire regarding patient participation. Data analyses were performed with descriptive statistics and ANCOVA. Results The results are based on a total of 222 completed questionnaires: 116 in the control group and 106 in the intervention group. It is uncertain whether the PFTP increased patient participation and information, but its use may indicate an improvement for the patient group. Conclusion A successful implementation strategy for the use of PFTP, with daily reconciliations, could be part of the work required to improve overall satisfaction with patient participation.
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| 22. |
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| 23. |
- Benkel, Inger, et al.
(author)
-
Family and friends provide most social support for the bereaved
- 2009
-
In: PALLIATIVE MEDICINE. - : SAGE Publications. - 0269-2163 .- 1477-030X. ; 23:2, s. 141-149
-
Journal article (peer-reviewed)abstract
- Social support is important in the bereavement period. In this study, the respondents were family members and friends to a patient who had died at a palliative care unit. The aim was to explore wishes and needs for, access to and effects of social support in the bereaved. We found that the grieving person’s wishes for social support from their network and the network also provided most social support. The network consisted of the close family, the origin family, relatives and friend. Support from the professional staff was required when the network was dysfunctional or when the grieving person did not want to burden members of his/her own network. The need for social support from professional staff was most needed close to the death and some time after.
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| 24. |
- Dickman, P. W., et al.
(author)
-
Hip fractures in men with prostate cancer treated with orchiectomy
- 2004
-
In: J Urol. - 0022-5347. ; 172:6 Pt 1, s. 2208-12
-
Journal article (peer-reviewed)abstract
- PURPOSE: Androgen deprivation therapy increases the risk of osteoporosis related fractures. This issue is of increasing importance in men with prostate cancer as increasingly more undergo androgen deprivation therapy and therapy is administered sooner following diagnosis. Data directly addressing the long-term fracture risk in men diagnosed with prostate cancer are limited. MATERIALS AND METHODS: Using population based registries in Sweden we studied the incidence of hip fractures in 17,731 men diagnosed with prostate cancer from 1964 to 1996 who were treated with bilateral orchiectomy within 6 months of diagnosis. The fracture incidence was compared to the incidence in 43,230 men diagnosed with prostate cancer but not treated with orchiectomy and in 362,354 of similar age who were randomly selected from the general population. RESULTS: Men treated with orchiectomy were at increased risk for hip fracture. The estimated relative risk comparing men who underwent orchiectomy to population controls was 2.11 (95% CI 1.94 to 2.29) for femoral neck fractures and 2.16 (95% CI 1.97 to 2.36) for intertrochanter fractures. An increased risk of hip fracture was observed as early as 6 months after orchiectomy and the relative risk remained fairly constant up to 15 years following orchiectomy. CONCLUSIONS: Hip fracture risk increases almost immediately following orchiectomy and the excess risk persists for at least 15 years. This side effect should be considered when assessing the merits of androgen deprivation therapy, particularly in symptom-free men diagnosed with localized prostate cancer. Measures to prevent osteoporosis should be considered in men undergoing androgen deprivation therapy.
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| 25. |
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| 26. |
- Hess, Wolfgang, et al.
(author)
-
The duration of trade revisited. Continuous-time versus discrete-time hazards
- 2012
-
In: Empirical Economics. - : Springer Science and Business Media LLC. - 0377-7332 .- 1435-8921. ; 43:3, s. 1083-1107
-
Journal article (peer-reviewed)abstract
- The recent literature on the duration of trade has predominantly analyzed the determinants of trade flow durations using Cox proportional hazards models. The purpose of this paper is to show why it is inappropriate to analyze the duration of trade with continuous-time models such as the Cox model, and to propose alternative discrete-time models which are more suitable for estimation. Briefly, the Cox model has three major drawbacks when applied to large trade data sets. First, it faces problems in the presence of many tied duration times, leading to biased coefficient estimates and standard errors. Second, it is difficult to properly control for unobserved heterogeneity, which can result in spurious duration dependence and parameter bias. Third, the Cox model imposes the restrictive and empirically questionable assumption of proportional hazards. By contrast, with discrete-time models there is no problem handling ties; unobserved heterogeneity can be controlled for without difficulty; and the restrictive proportional hazards assumption can easily be bypassed. By replicating an influential study by Besedeš and Prusa from 2006, but employing discrete-time models as well as the original Cox model, we find empirical support for each of these arguments against the Cox model. Moreover, when comparing estimation results obtained from a Cox model and our preferred discrete-time specification, we find significant differences in both the predicted hazard rates and the estimated effects of explanatory variables on the hazard. In other words, the choice between models affects the conclusions that can be drawn.
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| 27. |
- Hess, Wolfgang, et al.
(author)
-
The Duration of Trade Revisited. Continuous-Time vs. Discrete-Time Hazards
- 2011
-
Other publication (other academic/artistic)abstract
- The recent literature on the duration of trade has predominantly analyzed the determinants of trade flow durations using Cox proportional hazards models. The purpose of this paper is to show why it is inappropriate to analyze the duration of trade with continuous-time models such as the Cox model, and to propose alternative discrete-time models which are more suitable for estimation. Briefly, the Cox model has three major drawbacks when applied to large trade data sets. First, it faces problems in the presence of many tied duration times, leading to biased coefficient estimates and standard errors. Second, it is difficult to properly control for unobserved heterogeneity, which can result in spurious duration dependence and parameter bias. Third, the Cox model imposes the restrictive and empirically questionable assumption of proportional hazards. By contrast, with discrete-time models there is no problem handling ties; unobserved heterogeneity can be controlled for without difficulty; and the restrictive proportional hazards assumption can easily be bypassed. By replicating an influential study by Besedeš and Prusa from 2006, but employing discrete-time models as well as the original Cox model, we find empirical support for each of these arguments against the Cox model. Moreover, when comparing estimation results obtained from a Cox model and our preferred discrete-time specification, we find significant differences in both the predicted hazard rates and the estimated effects of explanatory variables on the hazard. In other words, the choice between models affects the conclusions that can be drawn.
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| 28. |
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| 29. |
- Noakes, DR, et al.
(author)
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Spin dynamics and freezing in magnetic rare-earth quasicrystals
- 1998
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In: PHYSICS LETTERS A. - : ELSEVIER SCIENCE BV. - 0375-9601. ; 238:2-3, s. 197-202
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Journal article (other academic/artistic)abstract
- Muon spin relaxation measurements of RE8Mg42Zn50 (RE = Gd, Tb) quasicrystals have revealed slower spin dynamics and more prompt spin freezing for Tb than Gd, due to "crystalline electric field" splitting in low rare-earth site symmetry. Inhomogeneous spin
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| 30. |
- Sabin, John R., et al.
(author)
-
Preface
- 2009
-
In: Advances in Quantum Chemistry. - : Academic Press. - 9780123747808 ; , s. ix-
-
Book chapter (pop. science, debate, etc.)
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| 31. |
- Sabin, L., et al.
(author)
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ALMA reveals the coherence of the magnetic field geometry in OH 231.8+4.2
- 2020
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 495:4, s. 4297-4305
-
Journal article (peer-reviewed)abstract
- In a continuing effort to investigate the role of magnetic fields in evolved low- and intermediate-mass stars (principally regarding the shaping of their envelopes), we present new Atacama Large Millimeter/submillimeter Array (ALMA) high-resolution polarization data obtained for the nebula OH 231.8+4.2. We found that the polarized emission likely arises from aligned grains in the presence of magnetic fields rather than radiative alignment and self-scattering. The ALMA data show well organized electric field orientations in most of the nebula and the inferred magnetic field vectors (rotated by 90 degrees) trace an hourglass morphology centred on the central system of the nebula. One region in the southern part of OH 231.8+4.2 shows a less organized distribution probably due to the shocked environment. These findings, in conjunction with earlier investigations (maser studies and dust emission analysis at other scales and wavelengths) suggest an overall magnetic hourglass located inside a toroidal field. We propose the idea that the magnetic field structure is closely related to the architecture of a magnetic tower and that the outflows were therefore magnetically launched. While the current dynamical effect of the fields might be weak in the equatorial plane principally due to the evolution of the envelope, it would still be affecting the outflows. In that regard, the measurement of the magnetic field at the stellar surface, which is still missing, combined with a full magnetohydrodynamic treatment are required to better understand and constrain the events occurring in OH 231.8+4.2.
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| 32. |
- Sabin, Susanna, et al.
(author)
-
A seventeenth-century Mycobacterium tuberculosis genome supports a Neolithic emergence of the Mycobacterium tuberculosis complex
- 2020
-
In: Genome Biology. - : Springer Science and Business Media LLC. - 1474-7596 .- 1474-760X. ; 21:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: Although tuberculosis accounts for the highest mortality from a bacterial infection on a global scale, questions persist regarding its origin. One hypothesis based on modern Mycobacterium tuberculosis complex (MTBC) genomes suggests their most recent common ancestor followed human migrations out of Africa approximately 70,000 years before present. However, studies using ancient genomes as calibration points have yielded much younger dates of less than 6000 years. Here, we aim to address this discrepancy through the analysis of the highest-coverage and highest-quality ancient MTBC genome available to date, reconstructed from a calcified lung nodule of Bishop Peder Winstrup of Lund (b. 1605-d. 1679). RESULTS: A metagenomic approach for taxonomic classification of whole DNA content permitted the identification of abundant DNA belonging to the human host and the MTBC, with few non-TB bacterial taxa comprising the background. Genomic enrichment enabled the reconstruction of a 141-fold coverage M. tuberculosis genome. In utilizing this high-quality, high-coverage seventeenth-century genome as a calibration point for dating the MTBC, we employed multiple Bayesian tree models, including birth-death models, which allowed us to model pathogen population dynamics and data sampling strategies more realistically than those based on the coalescent. CONCLUSIONS: The results of our metagenomic analysis demonstrate the unique preservation environment calcified nodules provide for DNA. Importantly, we estimate a most recent common ancestor date for the MTBC of between 2190 and 4501 before present and for Lineage 4 of between 929 and 2084 before present using multiple models, confirming a Neolithic emergence for the MTBC.
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| 34. |
- Sabine, Amelie, et al.
(author)
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FOXC2 and fluid shear stress stabilize postnatal lymphatic vasculature
- 2015
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In: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 125:10, s. 3861-3877
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Journal article (peer-reviewed)abstract
- Biomechanical forces, such as fluid shear stress, govern multiple aspects of endothelial cell biology. In blood vessels, disturbed flow is associated with vascular diseases, such as atherosclerosis, and promotes endothelial cell proliferation and apoptosis. Here, we identified an important role for disturbed flow in lymphatic vessels, in which it cooperates with the transcription factor FOXC2 to ensure lifelong stability of the lymphatic vasculature. In cultured lymphatic endothelial cells, FOXC2 inactivation conferred abnormal shear stress sensing, promoting junction disassembly and entry into the cell cycle. Loss of FOXC2-dependent quiescence was mediated by the Hippo pathway transcriptional coactivator TAZ and, ultimately, led to cell death. In murine models, inducible deletion of Foxc2 within the lymphatic vasculature led to cell-cell junction defects, regression of valves, and focal vascular lumen collapse, which triggered generalized lymphatic vascular dysfunction and lethality. Together, our work describes a fundamental mechanism by which FOXC2 and oscillatory shear stress maintain lymphatic endothelial cell quiescence through intercellular junction and cytoskeleton stabilization and provides an essential link between biomechanical forces and endothelial cell identity that is necessary for postnatal vessel homeostasis. As FOXC2 is mutated in lymphedema-distichiasis syndrome, our data also underscore the role of impaired mechanotransduction in the pathology of this hereditary human disease.
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| 35. |
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| 36. |
- Shoombuatong, Watshara, et al.
(author)
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Towards Predicting the Cytochrome P450 Modulation : From QSAR to proteochemometric modeling.
- 2017
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In: Current drug metabolism. - : Bentham Science Publishers Ltd.. - 1389-2002 .- 1875-5453. ; 18:6, s. 540-555
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Journal article (peer-reviewed)abstract
- Drug metabolism determines the fate of a drug when it enters the human body and is a critical factor in defining their absorption, distribution, metabolism, excretion and toxicity (ADMET) characteristics. Among the various drug metabolizing enzymes, cytochrome P450s (CYP450) constitute an important protein family that aside from functioning in xenobiotic metabolism is also responsible for a diverse array of other roles encompassing steroid and cholesterol biosynthesis, fatty acid metabolism, calcium homeostasis, neuroendocrine functions and growth regulation. Although CYP450 typically convert xenobiotics into safe metabolites, there are some situations whereby the metabolite is more toxic than its parent molecule. Computational modeling has been instrumental in CYP450 research by rationalizing the nature of the binding event (i.e. inhibit or induce CYP450s) or metabolic stability of query compounds of interest. A plethora of computational approaches encompassing ligand, structure and systems based approaches have been utilized to model CYP450-ligand interactions. This review provides a brief background on the CYP450 family (i.e. its roles, advantages and disadvantages as well as its modulators) and then discusses the various computational approaches that have been used to model CYP450-ligand interaction. Particular focus is given to the use of quantitative structure-activity relationship (QSAR) and more recent proteochemometric modeling studies. Finally, a perspective on the current state of the art and future trends of the field is provided.
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| 37. |
- Son, N. T., et al.
(author)
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Magnetic resonance identification ofhydrogen at a zinc vacancy in ZnO
- 2013
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In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 25, s. 335804-
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Journal article (peer-reviewed)abstract
- Hydrogen (H) at a zinc vacancy (VZn) in ZnO is identified by electron paramagnetic resonance(EPR) and electron spin echo envelope modulation (ESEEM). In ZnO irradiated by 2 MeVelectrons, a doublet EPR spectrum, labelled S1, is observed. The doublet structure and theaccompanying weak satellites are shown to be the allowed and forbidden lines of the hyperfinestructure due to the dipolar interaction between an electron spin S D 1=2 and a nuclear spinI D 1=2 of 1H located at a VZn. The involvement of a single H atom in the S1 defect is furtherconfirmed by the observation of the nuclear Zeeman frequency of 1H in ESEEM experiments.We show that at a VZn, H prefers to make a short O–H bond with one O neighbour and is offthe substitutional site, forming a low symmetry C1 defect. In this partly H passivated VZn, the unpaired electron localizes on the p orbital of another O neighbour of VZn, and not on the H.
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| 38. |
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| 39. |
- Thompson, Lachlan, et al.
(author)
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Survival, differentiation, and connectivity of ventral mesencephalic dopamine neurons following transplantation
- 2012
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In: Functional Neural Transplantation III : Primary and Stem Cell Therapies for Brain Repair, Part I - Primary and Stem Cell Therapies for Brain Repair, Part I. - 0079-6123. - 9780444595751 ; 200, s. 61-95
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Book chapter (peer-reviewed)abstract
- The reconstruction of midbrain dopamine (DA) circuitry through intracerebral transplantation of new DA neurons contained in embryonic ventral mesencephalon (VM) is a promising therapeutic approach for Parkinson's disease (PD). Although some of the early open-label trials have provided proof-of-principal that VM grafts can provide sustained improvement of motor function in some patients, subsequent trials showed that the functional response can be highly variable. This chapter reviews an extensive body of basic and clinical research on the survival, differentiation, and connectivity of DA neurons in VM grafts, and also looks at how these parameters are affected by certain host- and donor-specific variables. We also review how technical advances in the tools available to study the integration of grafted DA neurons, such as transgenic reporter mice, have made significant contributions to our understanding of the capacity of different DA neuronal subtypes for target-directed growth and innervation of appropriate host brain structures. Our established and on-going understanding of the capacity of grafted DA neurons to structurally and functionally integrate following transplantation forms an important basis for the refinement and optimization of VM grafting procedures, and also the development of new procedures based on the use of stem cells.
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| 40. |
- Van, Dung Pham, et al.
(author)
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Resource management for optical interconnects in data centre networks
- 2017
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In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509013289
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Conference paper (peer-reviewed)abstract
- This paper deals with resource management in data centre networks that feature optical interconnects. It first proposes an optical resource management framework as a platform to develop different solutions for multipoint-to-multipoint optical communication systems with a centralized controller. The paper takes optical intra-rack communications as an example application scenario of the framework and studies the intra-rack scheduling (IRS) problem using a theoretical approach. The problem is mapped into the classical open-shop scheduling problem, in which the optical interfaces are viewed as the jobs and the wavelengths used for communication among the interfaces are viewed as the machines. The IRS problem can therefore be solved by adopting the existing preemptive and/or non-preemptive open-shop scheduling algorithms. In a realistic intra-rack communication scenario with non-negligible network reconfiguration time, it is important to understand whether the preemptive or non-preemptive strategy provides better performance under given traffic conditions and system configurations. To address the question, this paper presents a performance analysis that allows to quantitatively compare the two scheduling strategies in terms of packet delay and potential energy savings obtained from sleep mode implementation. Analytical results reveal that the non-preemptive strategy outperforms the preemptive one for typical configurations used in data centre networks. In addition, the tuning and wake-up times of optical transceivers are shown to be key performance-determining factors. The proposed framework and obtained findings are not limited to the considered intra-rack communication scenario, but can be applied to any centralized optical switching systems featuring multipoint-to-multipoint transmissions with non-negligible reconfiguration time.
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| 41. |
- van, der Steeg W.A., et al.
(author)
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High-Density Lipoprotein Cholesterol, High-Density Lipoprotein Particle Size, and Apolipoprotein A-I : Significance for Cardiovascular Risk. The IDEAL and EPIC-Norfolk Studies
- 2008
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In: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 51:6, s. 634-642
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Journal article (peer-reviewed)abstract
- Objectives: This study was designed to assess the relationship of high-density-lipoprotein cholesterol (HDL-C), HDL particle size, and apolipoprotein A-I (apoA-I) with the occurrence of coronary artery disease (CAD), with a focus on the effect of very high values of these parameters. Background: High plasma levels of HDL-C and apoA-I are inversely related to the risk of CAD. However, recent data suggest that this relationship does not hold true for very high HDL-C levels, particularly when a preponderance of large HDL particles is observed. Methods: We conducted a post-hoc analysis of 2 prospective studies: the IDEAL (Incremental Decrease in End Points through Aggressive Lipid Lowering, n = 8,888) trial comparing the efficacy of high-dose to usual-dose statin treatment for the secondary prevention of cardiovascular events, and the EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk case-control study, including apparently healthy individuals who did (cases, n = 858) or did not (control patients, n = 1,491) develop CAD during follow-up. In IDEAL, only HDL-C and apoA-I were available, in EPIC-Norfolk, nuclear magnetic resonance spectroscopy-determined HDL particle sizes were also available. Results: In the IDEAL study, higher HDL-C proved a significant major cardiac event risk factor following adjustment for age, gender, smoking, apoA-I, and apoB. A similar association was observed for HDL particle size in EPIC-Norfolk. Increased risk estimates were particularly present in the high ends of the distributions. In contrast, apoA-I remained negatively associated across the major part of its distribution in both studies. Conclusions: When apoA-I and apoB are kept constant, HDL-C and HDL particle size may confer risk at very high values. This does not hold true for very high levels of apoA-I at fixed levels of HDL-C and apoB. These findings may have important consequences for assessment and treatment of CAD risk. © 2008 American College of Cardiology Foundation.
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