| 1. |
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- 2017
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In: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Journal article (peer-reviewed)
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| 2. |
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- 2019
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Journal article (peer-reviewed)
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| 3. |
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| 4. |
- Faatz, B., et al.
(author)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Journal article (peer-reviewed)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 5. |
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| 6. |
- Wacker, A, et al.
(author)
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Secondary structure determination of conserved SARS-CoV-2 RNA elements by NMR spectroscopy
- 2020
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In: Nucleic acids research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 48:22, s. 12415-12435
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Journal article (peer-reviewed)abstract
- The current pandemic situation caused by the Betacoronavirus SARS-CoV-2 (SCoV2) highlights the need for coordinated research to combat COVID-19. A particularly important aspect is the development of medication. In addition to viral proteins, structured RNA elements represent a potent alternative as drug targets. The search for drugs that target RNA requires their high-resolution structural characterization. Using nuclear magnetic resonance (NMR) spectroscopy, a worldwide consortium of NMR researchers aims to characterize potential RNA drug targets of SCoV2. Here, we report the characterization of 15 conserved RNA elements located at the 5′ end, the ribosomal frameshift segment and the 3′-untranslated region (3′-UTR) of the SCoV2 genome, their large-scale production and NMR-based secondary structure determination. The NMR data are corroborated with secondary structure probing by DMS footprinting experiments. The close agreement of NMR secondary structure determination of isolated RNA elements with DMS footprinting and NMR performed on larger RNA regions shows that the secondary structure elements fold independently. The NMR data reported here provide the basis for NMR investigations of RNA function, RNA interactions with viral and host proteins and screening campaigns to identify potential RNA binders for pharmaceutical intervention.
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| 7. |
- Bailey, D. L., et al.
(author)
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Combined PET/MRI : Global Warming-Summary Report of the 6th International Workshop on PET/MRI, March 27-29, 2017, Tubingen, Germany
- 2018
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In: Molecular Imaging and Biology. - : SPRINGER. - 1536-1632 .- 1860-2002. ; 20:1, s. 4-20
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Research review (peer-reviewed)abstract
- The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tubingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.
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| 8. |
- Janko, Matthew R., et al.
(author)
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In-situ bypass is associated with superior infection-free survival compared with extra-anatomic bypass for the management of secondary aortic graft infections without enteric involvement
- 2022
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In: Journal of Vascular Surgery. - : Elsevier. - 0741-5214 .- 1097-6809. ; 76:2, s. 546-
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Journal article (peer-reviewed)abstract
- Objective: The optimal revascularization modality following complete resection of aortic graft infection (AGI) without enteric involvement remains unclear. The purpose of this investigation is to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients undergoing complete excision of AGI. Methods: A retrospective, multi-institutional study of AGI from 2002 to 2014 was performed using a standardized database. Baseline demographics, comorbidities, and perioperative variables were recorded. The primary outcome was infection-free survival. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariable analyses were performed. Results: A total of 241 patients at 34 institutions from seven countries presented with AGI during the study period (median age, 68 years; 75% male). The initial aortic procedures that resulted in AGI were 172 surgical grafts (71%), 66 endografts (27%), and three unknown (2%). Of the patients, 172 (71%) underwent complete excision of infected aortic graft material followed by in situ (in-line) bypass (ISB), including antibiotic-treated prosthetic graft (35%), autogenous femoral vein (neo-aortoiliac surgery) (24%), and cryopreserved allograft (41%). Sixty-nine patients (29%) underwent extra-anatomic bypass (EAB). Overall median Kaplan-Meier estimated survival was 5.8 years. Perioperative mortality was 16%. When stratified by ISB vs EAB, there was a significant difference in Kaplan-Meier estimated infection-free survival (2910 days; interquartile range, 391-3771 days vs 180 days; interquartile range, 27-3750 days; P <.001). There were otherwise no significant differences in presentation, comorbidities, or perioperative variables. Multivariable Cox regression showed lower infection-free survival among patients with EAB (hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.6-3.6; P <.001), polymicrobial infection (HR, 2.2; 95% CI, 1.4-3.5; P = .001), methicillin-resistant Staphylococcus aureus infection (HR, 1.7; 95% CI, 1.1-2.7; P = .02), as well as the protective effect of omental/muscle flap coverage (HR, 0.59; 95% CI, 0.37-0.92; P = .02). Conclusions: After complete resection of AGI, perioperative mortality is 16% and median overall survival is 5.8 years. EAB is associated with nearly a two and one-half-fold higher reinfection/mortality compared with ISB. Omental and/or muscle flap coverage of the repair appear protective.
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| 9. |
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| 10. |
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| 11. |
- Zdziarski, J, et al.
(author)
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Molecular basis of commensalism in the urinary tract: low virulence or virulence attenuation?
- 2008
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In: Infection and Immunity. - 1098-5522. ; 76:2, s. 695-703
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Journal article (peer-reviewed)abstract
- In some patients Escherichia coli strains establish significant bacteriuria without causing symptoms of urinary tract infection (UTI). These asymptomatic bacteriuria (ABU) strains have been shown to express fewer virulence factors than the uropathogenic E. coli (UPEC) strains that cause severe, symptomatic UTI. Paradoxically, ABU strains carry many typical UPEC virulence genes, however, and the molecular basis of their low virulence therefore remains unclear. This study examined if ABU strains may evolve from UPEC by genome loss and virulence gene attenuation. The presence of conserved E. coli K-12 genes was examined using an E. coli K-12 strain MG1655-specific DNA array and the distribution of UPEC virulence-related genes with the E. coli pathoarray. Two groups of strains could be distinguished. Several ABU strains were shown by multi locus sequence typing and by comparative genomic analyses to be related to UPEC but to have smaller genome sizes. There were significant alterations in essential virulence genes, including reductive evolution by point mutations, DNA rearrangements and deletions. Other strains were unrelated to UPEC and lacked most of the virulence-associated genes. The results suggest that some ABU strains arise from virulent strains by attenuation of virulence genes while others are non-virulent and resemble commensal strains. We propose that virulence attenuation might constitute a general mechanism for mucosal pathogens to evolve towards commensalism.
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| 12. |
- Dribe, Martin, et al.
(author)
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Becoming American : Intermarriage during the great migration to the United States
- 2018
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In: Journal of Interdisciplinary History. - : MIT Press - Journals. - 1530-9169 .- 0022-1953. ; 49:2, s. 189-218
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Journal article (peer-reviewed)abstract
- Although intermarriage is a common indicator of immigrant integration into host societies, most research has focused on how individual characteristics determine intermarriage. This study uses the 1910 ipums census sample to analyze how contextual factors affected intermarriage among European immigrants in the United States. Newly available, complete-count census microdata permit the construction of contextual measures at a much lower level of aggregation—the county—in this analysis than in previous studies. Our results confirm most findings in previous research relating to individual-level variables but also find important associations between contextual factors and marital outcomes. The relative size and sex ratio of an origin group, ethnic diversity, the share of the native-born white population, and the proportion of life that immigrants spent in the United State are all associated with exogamy. These patterns are highly similar across genders and immigrant generations.
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| 13. |
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| 14. |
- Dribe, Martin, et al.
(author)
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Introduction to Fatal Years 30 Years Later: New Research on Child Mortality in the Past Special Issue
- 2023
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In: Social Science History. - 0145-5532. ; 47:3, s. 325-331
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Journal article (peer-reviewed)abstract
- 2021 marked the 30-year anniversary of the publication Fatal Years: Child Mortality in the late Nineteenth-Century United States, a pioneering work in historical demography by Samuel H. Preston and Michael R. Haines. This special issue showcases the current state of historical mortality studies through a collection of articles originally presented at two commemorative sessions at the 2021 meeting of the Social Science History Association. It provides new and more nuanced evidence on several of the major themes of Fatal Years in terms of the mortality experience and includes studies of a wide range of contexts, from North America, to Ireland, England and Wales, and continental Europe. They all bring new evidence and leverage the dramatic development that has taken place in availability of large-scale micro-level data in the 30 years since Fatal Years was published. This introduction first provides some background to the collection and then summarizes the main findings from the different articles included. Preston and Haines provide a coda to this collection with a short reflection article on researching and writing Fatal Years.
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| 15. |
- Dribe, Martin, et al.
(author)
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The impact of socio-economic status on net fertility during the historical fertility decline: A comparative analysis of Canada, Iceland, Sweden, Norway, and the USA.
- 2014
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In: Population Studies. - : Informa UK Limited. - 1477-4747 .- 0032-4728. ; 68:2, s. 135-149
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Journal article (peer-reviewed)abstract
- We used micro-level data from the censuses of 1900 to investigate the impact of socio-economic status on net fertility during the fertility transition in five Northern American and European countries (Canada, Iceland, Norway, Sweden, and the USA). The study is therefore unlike most previous research on the historical fertility transition, which used aggregate data to examine economic correlates of demographic behaviour at regional or national levels. Our data included information on number of children by age, occupation of the mother and father, place of residence, and household context. The results show highly similar patterns across countries, with the elite and upper middle classes having considerably lower net fertility early in the transition. These patterns remain after controlling for a range of individual and community-level fertility determinants and geographical unobserved heterogeneity.
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| 16. |
- Hacker, J David, et al.
(author)
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Wealth and Child Mortality in the Nineteenth-Century United States: Evidence from Three Panels of American Couples, 1850-1880
- 2023
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In: Social Science History. - 0145-5532. ; 47:3, s. 333-366
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Journal article (peer-reviewed)abstract
- With only a few exceptions, the historical study of individual-level correlates of child mortality in the United States has been limited to the period surrounding the turn of the twentieth century, when children ever born and children surviving data collected by the 1900 and 1910 censuses allow indirect estimation of child mortality. The recent release of linked census data, such as the IPUMS MLP datasets, allows a different type of indirect estimation over a longer period. By following couples across subsequent decennialcensuses, it is possible to infer child mortality by measuring whether couples’ own children in the first census were still present in the second census. We focus our analysis on children aged 1–3 in the first of two linked censuses, who were less likely to be undercounted by the census than infants, and unlikely to be living apart from their parents in the second census. We estimate child mortality over the intervening decade and use OLS regression to correlate that mortality to the residence location and socioeconomic characteristics of their parents’ households. We limit our analysis to three panel datasets for married couples linked between the 1850–60, 1860–70, and 1870–80 censuses, when real estate and personal estate wealth data were collected. Our results indicate a significant negative relationship between wealth and child mortality across all regions of the United States and over the entire period examined.
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| 17. |
- Hacker,, R Scott, 1964-, et al.
(author)
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A Bootstrap Test for Causality with Endogenous Lag Length Choice : theory and application in finance
- 2010
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Reports (other academic/artistic)abstract
- Granger causality tests have become among the most popular empirical applications with time series data. Several new tests have been developed in the literature that can deal with different data generating processes. In all existing theoretical papers it is assumed that the lag length is known a priori. However, in applied research the lag length has to be selected before testing for causality. This paper suggests that in investigating the effectiveness of various Granger causality testing methodologies, including those using bootstrapping, the lag length choice should be endogenized, by which we mean the data-driven preselection of lag length should be taken into account. We provide and accordingly evaluate a Granger-causality bootstrap test which may be used with data that may or may not be integrated, and compare the performance of this test to that for the analogous asymptotic test. The suggested bootstrap test performs well and appears to be also robust to ARCH effects that usually characterize the financial data. This test is applied to testing the causal impact of the US financial market on the market of the United Arab Emirates.
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| 18. |
- Hacker, R. Scott, et al.
(author)
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A bootstrap test for causality with endogenous lag length choice : theory and application in finance
- 2012
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In: Journal of economic studies. - : Emerald. - 0144-3585 .- 1758-7387. ; 39:2, s. 144-160
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Journal article (peer-reviewed)abstract
- Purpose – In all existing theoretical papers on causality it is assumed that the lag length is known a priori. However, in applied research the lag length has to be selected before testing for causality. The purpose of this paper is to suggest that in investigating the effectiveness of various Granger causality testing methodologies, including those using bootstrapping, the lag length choice should be endogenized, by which we mean the data-driven preselection of lag length should be taken into account.Design/methodology/approach – The size and power of a bootstrap test with endogenized lag-length choice are investigated by simulation methods. A statistical software component is produced to implement the test, which is available online.Findings – The simulation results show that this test performs well. An application of the test provides empirical support for the hypothesis that the UAE financial market is integrated with the US market.Social implications – The empirical results based on this test are expected to be more precise.Originality/value – This paper considers a bootstrap test for causality with endogenous lag order. This test has superior properties compared to existing causality tests in terms of size, with similar if not better power and it is robust to ARCH effects that usually characterize financial data. Practitioners interested in causal inference based on time series data might find the test valuable.
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| 19. |
- Hacker, R Scott, et al.
(author)
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A Test for Multivariate ARCH Effects
- 2005
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In: Applied Economics Letters. - : Informa UK Limited. - 1350-4851 .- 1466-4291. ; 12:7, s. 411-417
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Journal article (peer-reviewed)abstract
- This paper extends Engle's LM test for ARCH affects to multivariate cases. The size and power properties of this multivariate test for ARCH effects in VAR models are investigated based on asymptotic and bootstrap distributions. Using the asymptotic distribution, deviations of actual size from nominal size do not appear to be very excessive. Nevertheless, there is a tendency for the actual size to overreject the null hypothesis when the nominal size is 1% and underreject the null when the nominal size is 5% or 10%. It is found that using a bootstrap distribution for the multivariate LM test is generally superior in achieving the appropriate size to using the asymptotic distribution when (1) the nominal size is 5%; (2) the sample size is small (40 observations) and/or the VAR system is stable. With a small sample, the power of the test using the bootstrap distribution also appears better at the 5% nominal size.
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| 20. |
- Hacker, R Scott, et al.
(author)
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An Alternative Method to Test for Contagion with an Application to the Asian Financial Crisis
- 2005
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In: Applied Financial Economics Letters. - : Informa UK Limited. - 1744-6546 .- 1744-6554. ; 1:6, s. 343-347
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Journal article (peer-reviewed)abstract
- This paper investigates the size properties of a test for contagion based on an asymptotic t -distribution. The simulations show that this asymptotic test does not have correct size properties. An alternative test method based on case-resampling bootstrapping is introduced to improve on the correctness of inference. The simulations show that this new test has much better size properties. It also has quite high power properties and it is robust to ARCH effects. The method is applied to testing for contagion from Thailand to Indonesia during the Asian financial crisis.
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| 21. |
- Hacker, R Scott, et al.
(author)
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Capital Mobility in Sweden : A Time Varying Parameter Approach
- 2007
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In: Applied Economics Letters. - : Informa UK Limited. - 1350-4851 .- 1466-4291. ; 14:15, s. 1115-1118
-
Journal article (peer-reviewed)abstract
- This article investigates the degree of capital mobility in Sweden during 1993 to 2004 using quarterly data. A time varying parameter model is estimated by the Kalman filter, and it shows that the relationship between investment as share in gross domestic product (GDP) and saving as share in GDP is much less than one (within the interval of 0.25–0.35), indicating substantial capital mobility. However, since the coefficient in each period is statistically different from zero, capital is still not perfectly mobile. Nevertheless, capital mobility seems to have increased until 1995 when Sweden became a member of EU and after membership there seems to be no significant increase in capital mobility.
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| 22. |
- Hacker, R Scott, et al.
(author)
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How Productivity and Domestic Output Are Related to Exports and Foreign Output in the Case of Sweden
- 2003
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In: Empirical Economics. - : Springer Science and Business Media LLC. - 0377-7332 .- 1435-8921. ; 28:4, s. 767-782
-
Journal article (peer-reviewed)abstract
- In this paper we examine the relationships between two sets of three variables: Swedish real exports, Swedish real GDP, and foreign real GDP in one set; and Swedish real exports, Swedish total factor productivity, and foreign real GDP in the other set. The foreign real GDP facing Sweden is proxied by total OECD real GDP minus Sweden's real GDP. Multivariate tests for integration and cointegration show that the variables in each model are cointegrated. We also perform Granger causality tests on these variables in our examination using the Toda-Yamamoto procedure. We discover bi-directional causality between Swedish real exports and Swedish real GDP (or Swedish total factor productivity). Foreign real GDP is shown to Granger cause Swedish real exports, but no significant causation of foreign real GDP on either domestic GDP or total factor productivity was found. A change in foreign real GDP thus appears to affect Swedish output and productivity only indirectly, through changes in Swedish exports.
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| 23. |
- Hacker, R Scott, et al.
(author)
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Is the J-Curve Effect Observable for Small North European Economies?
- 2003
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In: Open Economies Review. - 0923-7992 .- 1573-708X. ; 14:2, s. 119-134
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Journal article (peer-reviewed)abstract
- The present study tests for the J-curve for five North European countries—Belgium, Denmark, The Netherlands, Norway, and Sweden—using generalized impulse response functions. The results provide empirical support for the J-curve. Each country has an impulse response function generated from a vector error-correction model that suggests that after a depreciation, there will be a dip in the export-import ratio within the first half-year after the depreciation. The long-run export-import ratio appears to be higher than the low point of this early dip in almost all cases. Also, in most cases, the export-import ratio appears in many periods after the depreciation to be converging from below to a higher long-run equilibrium.
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| 24. |
- Hacker, R. Scott, 1964-, et al.
(author)
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Model selection in time series analysis : using information criteria as an alternative to hypothesis testing
- 2022
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In: Journal of economic studies. - : Emerald Group Publishing Limited. - 0144-3585 .- 1758-7387. ; 49:6, s. 1055-1075
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Journal article (peer-reviewed)abstract
- Purpose: The issue of model selection in applied research is of vital importance. Since the true model in such research is not known, which model should be used from among various potential ones is an empirical question. There might exist several competitive models. A typical approach to dealing with this is classic hypothesis testing using an arbitrarily chosen significance level based on the underlying assumption that a true null hypothesis exists. In this paper, the authors investigate how successful the traditional hypothesis testing approach is in determining the correct model for different data generating processes using time series data. An alternative approach based on more formal model selection techniques using an information criterion or cross-validation is also investigated.Design/methodology/approach: Monte Carlo simulation experiments on various generating processes are used to look at the response surfaces resulting from hypothesis testing and response surfaces resulting from model selection based on minimizing an information criterion or the leave-one-out cross-validation prediction error.Findings: The authors find that the minimization of an information criterion can work well for model selection in a time series environment, often performing better than hypothesis-testing strategies. In such an environment, the use of an information criterion can help reduce the number of models for consideration, but the authors recommend the use of other methods also, including hypothesis testing, to determine the appropriateness of a model.Originality/value: This paper provides an alternative approach for selecting the best potential model among many for time series data. It demonstrates how minimizing an information criterion can be useful for model selection in a time-series environment in comparison to some standard hypothesis testing strategies.
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| 25. |
- Hacker, R Scott, 1964-, et al.
(author)
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Optimal lag-length choice in stable and unstable VAR models under situations of homoscedasticity and ARCH
- 2008
-
In: Journal of Applied Statistics. - : Routledge. - 0266-4763 .- 1360-0532. ; 35:6, s. 601-615
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Journal article (peer-reviewed)abstract
- The performance of different information criteria - namely Akaike, corrected Akaike (AICC), Schwarz-Bayesian (SBC), and Hannan-Quinn - is investigated so as to choose the optimal lag length in stable and unstable vector autoregressive (VAR) models both when autoregressive conditional heteroscedasticity (ARCH) is present and when it is not. The investigation covers both large and small sample sizes. The Monte Carlo simulation results show that SBC has relatively better performance in lag-choice accuracy in many situations. It is also generally the least sensitive to ARCH regardless of stability or instability of the VAR model, especially in large sample sizes. These appealing properties of SBC make it the optimal criterion for choosing lag length in many situations, especially in the case of financial data, which are usually characterized by occasional periods of high volatility. SBC also has the best forecasting abilities in the majority of situations in which we vary sample size, stability, variance structure (ARCH or not), and forecast horizon (one period or five). frequently, AICC also has good lag-choosing and forecasting properties. However, when ARCH is present, the five-period forecast performance of all criteria in all situations worsens.
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| 26. |
- Hacker, R. Scott, et al.
(author)
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Properties of Procedures Dealing with Uncertainty about Intercept and Deterministic Trend in Unit Root Testing
- 2014
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In: Empirical Economics Review. - 2222-9736. ; 3:1, s. 83-97
-
Journal article (peer-reviewed)abstract
- The classic Dickey-Fuller unit-root test can be applied using three different equations, depending upon the inclusion of a constant and/or a time trend in the regression equation. This paper investigates the size and power properties of a unit-root testing strategy outlined in Enders (2004), which allows for repeated testing of the unit root with the three equations depending on the significance of various parameters in the equations. This strategy is similar to strategies suggested by others for unit root testing. Our Monte Carlo simulation experiments show that serious mass significance problems prevail when using the strategy suggested by Enders. Excluding the possibility of unrealistic outcomes and using a priori information on whether there is a trend in the underlying time series, as suggested by Elder and Kennedy (2001), reduces the mass significance problem for the unit root test and improves power for that test. Subsequent testing for whether a trend exists is seriously affected by testing for the unit root first, however.
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| 27. |
- Hacker, R Scott, et al.
(author)
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Tests for Causality between Integrated Variables Using Asymptotic and Bootstrap Distributions : Theory and Application
- 2006
-
In: Applied Economics. - : Informa UK Limited. - 0003-6846 .- 1466-4283. ; 38:13, s. 1489-1500
-
Journal article (peer-reviewed)abstract
- Causality tests in the Granger's sense are increasingly applied in empirical research. Since the unit root revolution in time-series analysis, several modifications of tests for causality have been introduced in the literature. One of the recent developments is the Toda-Yamamoto modified Wald (MWALD) test, which is attractive due to its simple application, its absence of pre-testing distortions, and its basis on a standard asymptotical distribution irrespective of the number of unit roots and the cointegrating properties of the data. This study investigates the size properties of the MWALD test and finds that in small sample sizes this test performs poorly on those properties when using its asymptotical distribution, the chi-square. It is suggested that use be made of a leveraged bootstrap distribution to lower the size distortions. Monte Carlo simulation results show that an MWALD test based on a bootstrap distribution has much smaller size distortions than corresponding cases when the asymptotic distribution is used. These results hold for different sample sizes, integration orders, and error term processes (homoscedastic or ARCH). This new method is applied to the testing of the efficient market hypothesis
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| 28. |
- Hacker, R Scott, et al.
(author)
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The Effect of Exchange Rate Changes on Trade Balances in the Short and Long Run : Evidence from German Trade with Transitional Central European Economies
- 2004
-
In: The Economics of Transition. - : Wiley. - 0967-0750 .- 1468-0351. ; 12:4, s. 777-799
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Journal article (peer-reviewed)abstract
- Using generalized impulse response functions, this study tests for the trade J-curve for three transitional central European countries – the Czech Republic, Hungary, and Poland – in their bilateral trade with respect to Germany. Our findings suggest that for each country there are some characteristics associated with a J-curve effect: after a (real or nominal) depreciation the export-to-import ratio briefly drops to below its initial value within a few months and then rises to a long run equilibrium value higher than the initial one.
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| 29. |
- Hacker, R Scott, et al.
(author)
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The Effect of Regime Shifts on the Long-Run Relationships for Swedish Money Demand
- 2005
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In: Applied Economics. - : Informa UK Limited. - 0003-6846 .- 1466-4283. ; 37:15, s. 1731-1736
-
Journal article (peer-reviewed)abstract
- When the possibility of an unknown structural break is allowed and it is taken into account we find a significant long-run relationship between Swedish money demand and its determinants that is not found when no break is considered. The estimated elasticities show that money demand is more responsive to its determinants in the period after the break than before. Possible underlying reasons for the occurrence of this break and its implications are explained.
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| 30. |
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| 31. |
- Hacker, R Scott, 1964-, et al.
(author)
-
The Properties of Procedures Dealing with Uncertainty about Intercept and Deterministic Trend in Unit Root Testing
- 2010
-
Reports (other academic/artistic)abstract
- The classic Dickey-Fuller unit-root test can be applied using three different equations, depending upon the inclusion of a constant and/or a time trend in the regression equation. This paper investigates the size and power properties of a unit-root testing strategy outlined in Enders (2004), which allows for repeated testing of the unit root with the three equations depending on the significance of various parameters in the equations. This strategy is similar to strategies suggested by others for unit root testing. Our Monte Carlo simulation experiments show that serious mass significance problems prevail when using the strategy suggested by Enders. Excluding the possibility of unrealistic outcomes and using a priori information on whether there is a trend in the underlying time series, as suggested by Elder and Kennedy (2001), reduces the mass significance problem for the unit root test and improves power for that test. Subsequent testing for whether a trend exists is seriously affected by testing for the unit root first, however.
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| 32. |
- Hacker, R Scott, et al.
(author)
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Time-Varying Estimates for the Natural Rate of Unemployment and the Phillips Curve in the US Using the Kalman Filter : Journal of the Institute for International Economics
- 2005
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In: Economia Internazionale/International Economics. - : Camera di commercio, industria e agricoltura.. - 0012-981X. ; 58:3, s. 327-336
-
Journal article (peer-reviewed)abstract
- The objective of this study is to provide estimates of the Phillips curve in the US during the period 1951-2001 using some time-varying parameters and the Kalman filter. Time-varying estimates for the sensitivity of inflation to the unemployment rate are provided in addition to time-varying estimates for the NAIRU (the non-accelerating inflation rate of unemployment). Our results for the NAIRU do not significantly differ from that of others with time-varying estimates of it, with it peaking around 1980 (1979 in our case). Inflation is found to have become increasingly sensitive to unemployment in the late 1950s through the early 1970s, and peaked in the late 1970s – early 1980s. After that, the sensitivity decreased only slightly.
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| 33. |
- Hatemi-J, Abdulnasser, et al.
(author)
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An Alternative Method to Measure Contagion with an Application to the Asian Financial Crisis
- 2005
-
In: Applied Financial Economics Letters. - : Routledge. - 1744-6546 .- 1744-6554. ; 1:6, s. 343-347
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Journal article (peer-reviewed)abstract
- This paper investigates the size properties of a test for contagion based on an asymptotic t-distribution. The simulations show that this asymptotic test does not have correct size properties. An alternative test method based on case-resampling bootstrapping is introduced to improve on the correctness of inference. The simulations show that this new test has much better size properties. It also has quite high power properties and it is robust to ARCH effects. The method is applied to testing for contagion from Thailand to Indonesia during the Asian financial crisis.
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| 34. |
- Hatemi-J, Abdulnasser, et al.
(author)
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Can the LR Test Be Helpful in Choosing the Otpimal Lag Order in the VAR Model When Information Criteria Suggest Different Lag Orders?
- 2009
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In: Applied Economics. - : Informa UK Limited. - 0003-6846 .- 1466-4283. ; 41:9, s. 1121-1125
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Journal article (peer-reviewed)abstract
- The objective of this simulation study is to investigate whether the likelihood ratio (LR) test can pick the optimal lag order in the vector autoregressive model when the most applied information criteria (i.e. vector Schwarz--Bayesian, SBC and vector Hannan-Quinn, HQC) suggest two different lag orders. This lag-choosing procedure has been suggested by Hatemi-J (1999). The results based on the Monte Carlo simulations show that combining the LR test with SBC and HQC causes a substantial increase in the success rate of choosing the optimal lag order compared to cases when only SBC or HQC are used. This appears to be the case irrespective of homoscedasticity or conditional heteroscedasticity properties of the error-term in small sample sizes. This improvement in choosing the right lag order also tends to improve the forecasting capability of the underlying model.
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| 35. |
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| 36. |
- Jürgens, Julia J., et al.
(author)
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Going beyond CLEF-IP : The 'reality' for patent searchers?
- 2012
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In: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642332463 ; , s. 30-35
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Conference paper (peer-reviewed)abstract
- This paper gives an overview of several different approaches that have been applied by participants in the CLEF-IP evaluation initiative. On this basis, it is suggested that other techniques and experimental paradigms could be helpful in further improving the results and making the experiments more realistic. The field of information seeking is therefore incorporated and its potential gain for patent retrieval explained. Furthermore, the different search tasks that are undertaken by patent searchers are introduced as possible use cases. They can serve as a basis for development in patent retrieval research in that they present the diverse scenarios with their special characteristics and give the research community therefore a realistic picture of the patent user's work.
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| 37. |
- Kouokam, J Clavin, et al.
(author)
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Active cytotoxic necrotizing factor 1 associated with outer membrane vesicles from uropathogenic Escherichia coli.
- 2006
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In: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 74:4, s. 2022-2030
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Journal article (peer-reviewed)abstract
- Cytotoxic necrotizing factor type 1 (CNF1) is one of the virulence factors produced by uropathogenic Escherichia coli (UPEC). How this toxin is translocated from the bacterial cytoplasm to the surrounding environment is not well understood. Our data suggest that CNF1 may be regarded as a secreted protein, since it could be detected in culture supernatants. Furthermore, we found that CNF1 was tightly associated to outer membrane vesicles, suggesting that such vesicles play a role in the secretion of this protein. Interestingly, vesicle samples containing CNF1 could exert the effects known for this protein on HeLa cell cultures, showing that CNF1 is transported by vesicles in its active form. Taken together, our results strongly suggest that outer membrane vesicles could be a means for the bacteria to deliver CNF1 to the environment and to the infected tissue. In addition, our results indicate that the histone-like nucleoid structuring protein H-NS has a role in the downregulation of CNF1 production and that it affects the outer membrane vesicle release in UPEC strain J96.
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| 38. |
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| 39. |
- Mahoney, Craig, et al.
(author)
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Slope Estimation from ICESat/GLAS
- 2014
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In: Remote Sensing. - : MDPI AG. - 2072-4292. ; 6:10, s. 10051-10069
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Journal article (peer-reviewed)abstract
- We present a novel technique to infer ground slope angle from waveform LiDAR, known as the independent slope method (ISM). The technique is applied to large footprint waveforms (similar to 60 m mean diameter) from the Ice, Cloud and Land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) to produce a slope dataset of near-global coverage at 0.5 degrees x 0.5 degrees resolution. ISM slope estimates are compared against high resolution airborne LiDAR slope measurements for nine sites across three continents. ISM slope estimates compare better with the aircraft data (R-2 = 0.87 and RMSE = 5.16 degrees) than the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) inferred slopes (R-2 = 0.71 and RMSE = 8.69 degrees). ISM slope estimates are concurrent with GLAS waveforms and can be used to correct biophysical parameters, such as tree height and biomass. They can also be fused with other DEMs, such as SRTM, to improve slope estimates.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Trägårdh, Elin, et al.
(author)
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Reporting nuclear cardiology: a joint position paper by the European Association of Nuclear Medicine (EANM) and the European Association of Cardiovascular Imaging (EACVI).
- 2015
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In: European Heart Journal-Cardiovascular Imaging. - : Oxford University Press (OUP). - 2047-2412 .- 2047-2404. ; 16:3, s. 272-279
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Journal article (peer-reviewed)abstract
- The report of an imaging procedure is a critical component of an examination, being the final and often the only communication from the interpreting physician to the referring or treating physician. Very limited evidence and few recommendations or guidelines on reporting imaging studies are available; therefore, an European position statement on how to report nuclear cardiology might be useful. The current paper combines the limited existing evidence with expert consensus, previously published recommendations as well as current clinical practices. For all the applications discussed in this paper (myocardial perfusion, viability, innervation, and function as acquired by single photon emission computed tomography and positron emission tomography or hybrid imaging), headings cover laboratory and patient demographics, clinical indication, tracer administration and image acquisition, findings, and conclusion of the report. The statement also discusses recommended terminology in nuclear cardiology, image display, and preliminary reports. It is hoped that this statement may lead to more attention to create well-written and standardized nuclear cardiology reports and eventually lead to improved clinical outcome.
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| 46. |
- Trägårdh, Elin, et al.
(author)
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Systematic review of cost-effectiveness of myocardial perfusion scintigraphy in patients with ischaemic heart disease A report from the cardiovascular committee of the European Association of Nuclear Medicine. Endorsed by the European Association of Cardiovascular Imaging
- 2017
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In: European Heart Journal Cardiovascular Imaging. - : Oxford University Press (OUP). - 2047-2404 .- 2047-2412. ; 18:8, s. 825-832
-
Research review (peer-reviewed)abstract
- Coronary artery disease (CAD) is a major cause of death and disability. Several diagnostic tests, such as myocardial perfusion scintigraphy (MPS), are accurate for the detection of CAD, as well as having prognostic value for the prediction of cardiovascular events. Nevertheless, the diagnostic and prognostic value of these tests should be cost-effective and should lead to improved clinical outcome. We have reviewed the literature on the cost-effectiveness of MPS in different circumstances: (i) the diagnosis and management of CAD; (ii) comparison with exercise electrocardiography (ECG) and other imaging tests; (iii) as gatekeeper to invasive coronary angiography (ICA), (iv) the impact of appropriate use criteria; (v) acute chest pain, and (vi) screening of asymptomatic patients with type-2 diabetes. In total 57 reports were included. Although most non-invasive imaging tests are cost-effective compared with alternatives, the data conflict on which non-invasive strategy is the most cost-effective. Different definitions of cost-effectiveness further confound the subject. Computer simulations of clinical diagnosis and management are influenced by the assumptions made. For instance, diagnostic accuracy is often defined against an anatomical standard that is wrongly assumed to be perfect. Conflicting data arise most commonly from these incorrect or differing assumptions.
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| 47. |
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| 48. |
- Wu, Cheng, 1985, et al.
(author)
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Impacts of soil moisture on de novo monoterpene emissions from European beech, Holm oak, Scots pine, and Norway spruce
- 2015
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In: Biogeosciences. - 1726-4170 .- 1726-4189. ; 12, s. 177-191
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Journal article (peer-reviewed)abstract
- Impacts of soil moisture on de novo monoterpene (MT) emissions from Holm oak, European beech, Scots pine, and Norway spruce were studied in laboratory experiments. The volumetric water content of the soil, Θ, was used as the reference quantity to parameterize the dependency of MT emissions on soil moisture and to characterize the severity of the drought. When θ dropped from 0.4m3 ×m-3 to ∼0.2m3 ×m-3 slight increases of de novo MT emissions were observed but with further progressing drought the emissions decreased to almost zero. In most cases the increases of MT emissions observed under conditions of mild drought were explainable by increases of leaf temperature due to lowered transpirational cooling. When Θ fell below certain thresholds, MT emissions decreased simultaneously with 2 and the relationship between Θ and MT emissions was approximately linear. The thresholds of θ (0.044-0.19m3 ×m-3) were determined, as well as other parameters required to describe the soil moisture dependence of de novo MT emissions for application in the Model of Emissions of Gases and Aerosols from Nature, MEGAN. A factorial approach was found appropriate to describe the impacts of 2, temperature, and light. Temperature and θ influenced the emissions largely independently from each other, and, in a similar manner, light intensity and θ acted independently on de novo MT emissions. The use of θ as the reference quantity in a factorial approach was tenable in predicting constitutive de novo MT emissions when θ changed on a time scale of days. Empirical parameterization with θ as a reference was only unsuccessful when soil moisture changed rapidly
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