115 research outputs found
Characteristics of lapsed German whole blood donors and barriers to return four years after the initial donation
Background: The aim of the study was to identify characteristics of lapsed donors 4 years after the initial donation as well as self-reported barriers to return for further blood donations. Methods: A random number of 8,000 blood donors, donating for the German Red Cross Blood Service Baden-Wurttemberg - Hessen, were asked to fill in a self-administered questionnaire. The response rate was 38.5%. Donors were categorized as ”lapsed’ if they had not donated within the last 24 months. The odds of being a lapsed donor were determined in a multivariate logistic regression. Results: Multivariate analysis showed that lapsed donors were more likely to be female, between 26 and 33 years old, not employed, have moved, and were dissatisfied with the last donation experience. Furthermore, lapsed donors were less likely to have family members or friends who also donate blood. Medical reasons and having moved to another city were the most frequently named reasons preventing lapsed donors from continuing to donate blood. Conclusion: The importance of medical reasons and having moved was rated much higher than in previous studies. We conclude that barriers to return may vary considerably between countries and blood services. Therefore, donor surveys are required to guide reactivation campaigns
Der Einfluss von KontrollĂĽberzeugungen der Interviewer auf die Teilnahme an telefonischen Befragungen
'Um Unterschiede in der Überzeugungskraft von Interviewern in telefonischen Befragungen besser zu verstehen, wird der Erklärungsbeitrag von Kontrollüberzeugungen der Interviewer für die Teilnahmebereitschaft von potentiellen Interviewpartnern an Befragungen bestimmt. Studien zu Kontrollüberzeugungen aus anderen Berufszweigen lassen die Annahme zu, dass Interviewer mit einer starken internalen Kontrollüberzeugung, die also das eigene Handeln und die gewählten Strategien als ausschlaggebend für Erfolg und Misserfolg erachten, höhere Erfolgsquoten aufweisen. Diese These wird anhand von Daten des am Robert Koch-Institut erhobenen Telefonischen Gesundheitssurveys 2007 überprüft. Wie sich in logistischen Mehrebenenregressionen zeigt, haben Interviewer mit hoher internaler Kontrollüberzeugung tatsächlich höhere Erfolgsquoten. Kontrollüberzeugungen der Interviewer und die damit verbundenen Nutzenerwartungen hinsichtlich der eigenen Bemühungen können somit einen eigenständigen Beitrag leisten, um die Unterschiede in den Erfolgsquoten der Interviewer zu erklären. Wie sich weiter zeigt, sind Kontrollüberzeugungen allerdings kein geeignetes Kriterium, um Interviewer für Anrufe mit einer schwierigen Ausgangsbasis auszuwählen.' (Autorenreferat)'In order to reach a better understanding of the differences in persuasive power of interviewers conducting telephone polls this explanatory contribution is dealing with the locus of control of these interviewers and the rate of their success at persuading potential interviewees to take part in such surveys. Studies on the locus of control in other professions assume an increase in the rate of success for interviewers with a strong internal locus of control. This hypothesis is tested on the basis of data from the Telephone Health Survey 2007 conducted by the Robert Koch-Institute. Results from a logistic multilevel model show that interviewers with high internal locus of control really have higher success rates. These results underline the influence that the convictions and the expectations of the interviewers have on the rate of participation in telephone interviews. However, locus of control does not appear to be a valid interviewer selection criterion when the goal is to convince target persons who are averse to surveys. ' (author's abstract)
Donor deferral rates after the implementation of a new German blood donor questionnaire
Background: The implementation of a new national German blood donor questionnaire was proposed to improve donor and recipient safety. Methods: We compared deferral/exclusion rates of whole blood donors before (May 2010, n = 64,735)
and after (May 2011, n = 71,687) the implementation of a new
blood donor questionnaire. Considering seasonal variations,
analysis was performed with respect to collection site (mobile vs. fixed), sex, donor status (first-time vs. repeat), age, and the frequencies of sexual risk behavior and other reasons for deferral. Results: We observed a statistically significant increase (p < 0.001) of the overall deferral/exclusion rate from 6.2 to 8.1%, irrespective of type of collection site (fixed: from 6.0 to
8.5%; mobile: from 6.2 to 8.0%), sex (females: from 7.5 to 9.9%; males: from 5.1 to 6.6%), donor status (first-time donors: from 19.7 to 24.7%; repeat donors: from 4.6 to 6.3%) or age (18–29 years: from 9.1 to 11.7%; 60–71 years: from 5.1 to 6.6%). Confidential self-exclusion increased from 0.08 to 0.14% (p < 0.001). Besides risk behavior, various medical reasons could be identified that explain this increase. Conclusions: The new blood donor questionnaire resulted in an increased deferral/exclusion of all donor groups. Thus the impact on future blood supply
must be considered carefully, and long-term studies and
investigation of donor acceptance will be needed
Spectral Bounds for Dirac Operators on Open Manifolds
We extend several classical eigenvalue estimates for Dirac operators on
compact manifolds to noncompact, even incomplete manifolds. This includes
Friedrich's estimate for manifolds with positive scalar curvature as well as
the author's estimate on surfaces.Comment: pdflatex, 14 pages, 3 figure
Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO2, CH4, and CO
The Total Carbon Column Observing Network (TCCON) is the baseline ground-based network of instruments that record solar absorption spectra from which accurate and precise column-averaged dry-air mole fractions of CO (XCO), CH (XCH), CO (XCO), and other gases are retrieved. The TCCON data have been widely used for carbon cycle science and validation of satellites measuring greenhouse gas concentrations globally. The number of stations in the network (currently about 25) is limited and has a very uneven geographical coverage: the stations in the Northern Hemisphere are distributed mostly in North America, Europe, and Japan, and only 20 % of the stations are located in the Southern Hemisphere, leaving gaps in the global coverage. A denser distribution of ground-based solar absorption measurements is needed to improve the representativeness of the measurement data for various atmospheric conditions (humid, dry, polluted, presence of aerosol), various surface conditions such as high albedo (>0.4) and very low albedo, and a larger latitudinal distribution. More stations in the Southern Hemisphere are also needed, but a further expansion of the network is limited by its costs and logistical requirements. For this reason, several groups are investigating supplemental portable low-cost instruments. The European Space Agency (ESA) funded campaign Fiducial Reference Measurements for Ground-Based Infrared Greenhouse Gas Observations (FRM4GHG) at the Sodankylä TCCON site in northern Finland aims to characterise the assessment of several low-cost portable instruments for precise solar absorption measurements of XCO, XCH, and XCO. The test instruments under investigation are three Fourier transform spectrometers (FTSs): a Bruker EM27/SUN, a Bruker IRcube, and a Bruker Vertex70, as well as a laser heterodyne spectroradiometer (LHR) developed by the UK Rutherford Appleton Laboratory. All four remote sensing instruments performed measurements simultaneously next to the reference TCCON instrument, a Bruker IFS 125HR, for a full year in 2017. The TCCON FTS was operated in its normal high-resolution mode (TCCON data set) and in a special low-resolution mode (HR125LR data set), similar to the portable spectrometers. The remote sensing measurements are complemented by regular AirCore launches performed from the same site. They provide in situ vertical profiles of the target gas concentrations as auxiliary reference data for the column retrievals, which are traceable to the WMO SI standards. The reference measurements performed with the Bruker IFS 125HR were found to be affected by non-linearity of the indium gallium arsenide (InGaAs) detector. Therefore, a non-linearity correction of the 125HR data was performed for the whole campaign period and compared with the test instruments and AirCore. The non-linearity-corrected data (TCCONmod data set) show a better match with the test instruments and AirCore data compared to the non-corrected reference data. The time series, the bias relative to the reference instrument and its scatter, and the seasonal and the day-to-day variations of the target gases are shown and discussed. The comparisons with the HR125LR data set gave a useful analysis of the resolution-dependent effects on the target gas retrieval. The solar zenith angle dependence of the retrievals is shown and discussed. The intercomparison results show that the LHR data have a large scatter and biases with a strong diurnal variation relative to the TCCON and other FTS instruments. The LHR is a new instrument under development, and these biases are currently being investigated and addressed. The campaign helped to characterise and identify instrumental biases and possibly retrieval biases, which are currently under investigation. Further improvements of the instrument are ongoing. The EM27/SUN, the IRcube, the modified Vertex70, and the HR125LR provided stable and precise measurements of the target gases during the campaign with quantified small biases. The bias dependence on the humidity along the measurement line of sight has been investigated and no dependence was found. These three portable low-resolution FTS instruments are suitable to be used for campaign deployment or long-term measurements from any site and offer the ability to complement the TCCON and expand the global coverage of ground-based reference measurements of the target gases
Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO2, CH4, and CO
The Total Carbon Column Observing Network (TCCON) is the baseline ground-based network of instruments that record solar absorption spectra from which accurate and precise column-averaged dry-air mole fractions of CO (XCO), CH (XCH), CO (XCO), and other gases are retrieved. The TCCON data have been widely used for carbon cycle science and validation of satellites measuring greenhouse gas concentrations globally. The number of stations in the network (currently about 25) is limited and has a very uneven geographical coverage: the stations in the Northern Hemisphere are distributed mostly in North America, Europe, and Japan, and only 20 % of the stations are located in the Southern Hemisphere, leaving gaps in the global coverage. A denser distribution of ground-based solar absorption measurements is needed to improve the representativeness of the measurement data for various atmospheric conditions (humid, dry, polluted, presence of aerosol), various surface conditions such as high albedo (>0.4) and very low albedo, and a larger latitudinal distribution. More stations in the Southern Hemisphere are also needed, but a further expansion of the network is limited by its costs and logistical requirements. For this reason, several groups are investigating supplemental portable low-cost instruments. The European Space Agency (ESA) funded campaign Fiducial Reference Measurements for Ground-Based Infrared Greenhouse Gas Observations (FRM4GHG) at the Sodankylä TCCON site in northern Finland aims to characterise the assessment of several low-cost portable instruments for precise solar absorption measurements of XCO, XCH, and XCO. The test instruments under investigation are three Fourier transform spectrometers (FTSs): a Bruker EM27/SUN, a Bruker IRcube, and a Bruker Vertex70, as well as a laser heterodyne spectroradiometer (LHR) developed by the UK Rutherford Appleton Laboratory. All four remote sensing instruments performed measurements simultaneously next to the reference TCCON instrument, a Bruker IFS 125HR, for a full year in 2017. The TCCON FTS was operated in its normal high-resolution mode (TCCON data set) and in a special low-resolution mode (HR125LR data set), similar to the portable spectrometers. The remote sensing measurements are complemented by regular AirCore launches performed from the same site. They provide in situ vertical profiles of the target gas concentrations as auxiliary reference data for the column retrievals, which are traceable to the WMO SI standards. The reference measurements performed with the Bruker IFS 125HR were found to be affected by non-linearity of the indium gallium arsenide (InGaAs) detector. Therefore, a non-linearity correction of the 125HR data was performed for the whole campaign period and compared with the test instruments and AirCore. The non-linearity-corrected data (TCCONmod data set) show a better match with the test instruments and AirCore data compared to the non-corrected reference data. The time series, the bias relative to the reference instrument and its scatter, and the seasonal and the day-to-day variations of the target gases are shown and discussed. The comparisons with the HR125LR data set gave a useful analysis of the resolution-dependent effects on the target gas retrieval. The solar zenith angle dependence of the retrievals is shown and discussed. The intercomparison results show that the LHR data have a large scatter and biases with a strong diurnal variation relative to the TCCON and other FTS instruments. The LHR is a new instrument under development, and these biases are currently being investigated and addressed. The campaign helped to characterise and identify instrumental biases and possibly retrieval biases, which are currently under investigation. Further improvements of the instrument are ongoing. The EM27/SUN, the IRcube, the modified Vertex70, and the HR125LR provided stable and precise measurements of the target gases during the campaign with quantified small biases. The bias dependence on the humidity along the measurement line of sight has been investigated and no dependence was found. These three portable low-resolution FTS instruments are suitable to be used for campaign deployment or long-term measurements from any site and offer the ability to complement the TCCON and expand the global coverage of ground-based reference measurements of the target gases
Erfahrungen, Herausforderungen und Lösungsansätze aus der Extraktion pseudonymer Daten für das Projekt INDEED
Background: In Germany there is currently no health reporting on cross-sectoral care patterns in the context of an emergency department care treatment. The INDEED project (Utilization and trans-sectoral patterns of care for patients admitted to emergency departments in Germany) collects routine data from 16 emergency departments, which are later merged with outpatient billing data from 2014 to 2017 on an individual level.
Aim: The methodological challenges in planning of the internal merging of routine clinical and administrative data from emergency departments in Germany up to the final data extraction are presented together with possible solution approaches.
Methods: Data were selected in an iterative process according to the research questions, medical relevance, and assumed data availability. After a preparatory phase to clarify formalities (including data protection, ethics), review test data and correct if necessary, the encrypted and pseudonymous data extraction was performed.
Results: Data from the 16 cooperating emergency departments came mostly from the emergency department and hospital information systems. There was considerable heterogeneity in the data. Not all variables were available in every emergency department because, for example, they were not standardized and digitally available or the extraction effort was judged to be too high.
Conclusion: Relevant data from emergency departments are stored in different structures and in several IT systems. Thus, the creation of a harmonized data set requires considerable resources on the part of the hospital as well as the data processing unit. This needs to be generously calculated for future projects
Filovirus RefSeq Entries: Evaluation and Selection of Filovirus Type Variants, Type Sequences, and Names
Sequence determination of complete or coding-complete genomes of viruses is becoming common practice for supporting the work of epidemiologists, ecologists, virologists, and taxonomists. Sequencing duration and costs are rapidly decreasing, sequencing hardware is under modification for use by non-experts, and software is constantly being improved to simplify sequence data management and analysis. Thus, analysis of virus disease outbreaks on the molecular level is now feasible, including characterization of the evolution of individual virus populations in single patients over time. The increasing accumulation of sequencing data creates a management problem for the curators of commonly used sequence databases and an entry retrieval problem for end users. Therefore, utilizing the data to their fullest potential will require setting nomenclature and annotation standards for virus isolates and associated genomic sequences. The National Center for Biotechnology Information’s (NCBI’s) RefSeq is a non-redundant, curated database for reference (or type) nucleotide sequence records that supplies source data to numerous other databases. Building on recently proposed templates for filovirus variant naming [ ()////-], we report consensus decisions from a majority of past and currently active filovirus experts on the eight filovirus type variants and isolates to be represented in RefSeq, their final designations, and their associated sequences
VISTA Variables in the <i>VĂa Láctea</i> (VVV): Halfway Status and Results
The VISTA Variables in the VĂa Láctea (VVV) survey is one of six near-infrared ESO public surveys, and is now in its fourth year of observing. Although far from being complete, the VVV survey has already delivered many results, some directly connected to the intended science goals (detection of variable stars, microlensing events, new star clusters), others concerning more exotic objects, e.g., novae. Now, at the end of the fourth observing period, and comprising roughly 50% of the proposed observations, the status of the survey, as well some of results based on the VVV data, are presented.Facultad de Ciencias AstronĂłmicas y GeofĂsica
On the in-situ manufacture of thermoplastic sandwich structures with continuous fibre reinforced facesheets and integral foam cores: Zur In-Situ Herstellung thermoplastischer Sandwichstrukturen mit endlosfaserverstärkten Decklagen und Integralschaumkernen
Steigende Anforderungen an kosteneffizienten Leichtbau insbesondere im Automobilbereich, haben zur Entwicklung neuartiger hybrider Verfahren zur Herstellung von Bauteilen aus Endlosfaser verstärkten Thermoplasten (engl. continuous fibre reinforced thermoplastics, CFRTP) beigetragen. Ein vielversprechendes Beispiel ist der in-situ CFRTP-Sandwichprozess, der das Umspritzen von Basisstrukturen CFRTP mit dem Schaumspritzgießverfahren kombiniert. Dieser hybride Prozess ermöglicht die Fertigung funktionsintegrierter CFRTP-Sandwichbauteile mit hohen gewichtsspezifischen mechanischen Eigenschaften und komplexer Geometrie in niedrigen Zykluszeiten. Für die Anwendung dieses Prozesses in der industriellen Fertigung solcher in-situ Bauteile sind jedoch Methoden zu deren Vorauslegung notwendig. Diesbezüglich bestehen aktuell grundsätzliche wissenschaftliche Herausforderungen, die zunächst adressiert werden müssen. Dies sind insbesondere der kritische Aspekt der Grenzflächenverbindung zwischen CFRTP-Decklagen und spritzgegossenem Schaumkern sowie auf das daraus resultierende gewichtsspezifische mechanische Verhalten in Abhängigkeit der Material- und Prozessparameter.
In diesem Zusammenhang setzt sich die vorliegende Arbeit zum Ziel, die Mechanismen der Grenzflächenverschweißung bei der in-situ-Herstellung von CFRTP-Sandwichstrukturen zu ermitteln. Darüber hinaus wird der Zusammenhang zwischen Prozess- sowie Materialparametern und dem daraus resultierenden gewichtsspezifischen Biegeverhalten dieser in-situ Sandwichbauteile untersucht. Damit soll der Grundstein gelegt werden für die Entwicklung von Methoden zur Vorauslegung von in-situ CFRTP-Sandwichstrukturen.
Für die quantitative Bewertung der Grenzflächenverschweißung von in-situ CFRTP-Sandwichstrukturen müssen zunächst geeignete Prüfverfahren etabliert werden. Anschließend werden experimentelle Kampagnen durchgeführt, um jene Mechanismen zu evaluieren, die für die Ausbildung der Grenzflächenverbindung während des in-situ Prozesses verantwortlich sind. Nach einer Fokussierung auf die polymerspezifischen Anbindungsmechanismen, wird der Einfluss von chemischen und physikalischen Treibmitteln auf die Verschweißung von CFRTP-Deckschicht und Schaumkern untersucht.
Weiterhin wird das inhärente Leichtbaupotenzial von in-situ CFRTP-Sandwichstrukturen anhand der gewichtsspezifischen Biegesteifigkeit bewertet. Dazu werden die durch Material- und Prozessparameter induzierte Schaummorphologie sowie die entsprechenden gewichtsspezifischen Biegeeigenschaften von in-situ CFRTP-Sandwichproben mittels Mikrocomputertomographie sowie Vierpunktbiegeversuchen evaluiert.
Basierend auf diesen Untersuchungen werden modellbasierte Methoden zur Vorhersage der Grenzflächenbindung sowie des gewichtsspezifischen Biegeverhaltens von in-situ CFRTP-Sandwichstrukturen entwickelt und anhand experimenteller Daten validiert.
Um die Anwendbarkeit der in dieser Arbeit entwickelten Methoden in der Ingenieurspraxis zu demonstrieren, werden sie zur Vorlauslegung von in-situ CFRTP-Sandwichbauteilen als Substitution einer Stahlreferenzkomponente eingesetzt. Dies soll weiterhin das vielversprechende Potenzial fĂĽr einen kosteneffizienten Leichtbau von in-situ CFRTP-Sandwichbauteilen unterstreichen.Novel hybrid processes for the manufacture of continuous fibre reinforced thermoplastic (CFRTP) components have been emerging, due to increasing requirements regarding cost-efficient lightweight design especially in the automotive sector. A promising example is the in-situ CFRTP sandwich process, which combines overmoulding of thermoplastic composites with foam injection moulding. This hybrid process enables function-integrated components with high weight specific mechanical properties and complex geometry at low cycle times. However, methods for the pre-design of in-situ CFRTP sandwich components are required for the application of this process in industrial component manufacture. Therefore, several challenges must be met especially with respect to the critical aspect of interfacial bonding between CFRTP facesheets and injection moulded core as well as to the resulting weight specific mechanical behaviour depending on the material and process parameters.
In this context, the present work aims to clarify the mechanisms behind the interfacial bonding development during the in-situ manufacture of CFRTP sandwich specimens. Furthermore, the relationship between process as well as material parameters and the resulting weight specific flexural behaviour of sandwich components is evaluated. This shall lay the foundation for the development of methods, which enable the mechanical modelling of in-situ CFRTP sandwich structures and thereby facilitate the pre-design of new components.
For the quantitative evaluation of the interfacial bonding of in-situ CFRTP sandwich structures, suitable test methods need to be established at first. Subsequently, experimental campaigns are conducted in order to evaluate the mechanisms responsible for the development of interfacial bonding during the in-situ process. Therefore, polypropylene-based in-situ CFRTP sandwich specimens are manufactured and subsequently object of mechanical testing and analysis. After focusing on an investigation of the polymer specific bonding mechanisms, the effect of chemical and physical blowing agents on the interfacial bonding of facesheet and core is determined.
In addition, the inherent lightweight design potential of in-situ CFRTP sandwich structures is evaluated, represented by the weight specific flexural rigidity. For this purpose, the foam morphology that is induced by material and process parameters as well as the corresponding weight specific flexural properties of sandwich specimens are assessed via micro computer tomography and four-point bending tests respectively.
Based on these studies, model based predictive characterisations of the interfacial bonding as well as of the weight specific flexural behaviour of in-situ CFRTP sandwich structures are developed and evaluated using experimental data.
In order to demonstrate the applicability of the developed models in the pre-design of in-situ sandwich components, they are used for the substitution of a steel reference component. This shall further highlight the promising potential regarding cost-efficient lightweight design of in-situ CFRTP sandwich structures
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