Modeling Meteoroid Densities for Spacecraft Risk Assessment

This report describes the methodologies and algorithms that NASAs Meteoroid Environment Office (MEO) currently utilizes to measure meteoroid densities. We discuss the needs for an accurate model for the meteoroid density distribution in its Meteoroid Engineering Model (MEM), and its potential implications for spacecraft design. The recently developed process is heavily derived from that of previous work, although subtle differences exist. A thorough comparison of the best-fit densities derived for sixty meteoroids in and with the process described here shows that discrepancies in final densities larger than a factor of two are measured for 20% of our test events. Such a level of discrepancy suggests that any density calculated using similar methods cannot be assumed to represent a unique fit to the data. Additional observational data for meteoroids beyond those utilized in this work will be essential for producing more reliable and repeatable density measurements

Health Effects of Temporary Jobs in Europe

Over the last two decades, temporary employment has gained importance in the European Union. The implications of this development for the health of the workforce are not yet established. Using a unique individual-level data set for 27 European countries, this paper evaluates whether temporary employment is interrelated with self-assessed health. We find pronounced differences in self-assessed health by employment status across European countries. Furthermore, in the EU full-time permanent employed workers report the best health, followed by temporary and part-time employed workers. These differences largely vanish, when taking into account the potential endogeneity between employment status and self-assessed health. However, repeated temporary contracts have a significant negative impact on health.Temporary employment; fixed-term contracts; self-assessed health

Erfassung, Identifizierung, Vermehrung und Wiederansiedlung der Schwarzpappel Populus nigra in Sachsen-Anhalt

Durch den Flußlauf der Elbe und ihre Nebenflüsse sind in Sachsen-Anhalt aktuelle und potentielle Vorkommensgebiete der Schwarzpappel (Populus nigra) vorhanden. Die natürlichen Standorte der Schwarzpappel sind die Übergangszonen von Weichholzund Hartholzaue (ELLENBERG 1996), wie sie an naturnahen Flußufern zu finden sind. Im Gegensatz zu anderen Baumarten erträgt die Schwarzpappel wie auch Baumweidenarten Hochwasserstände von bis zu 90 Tagen und damit mittlere Hochwässer. Auf Grund der Konkurrenz der Baumarten der Hartholzaue und - wenn überhaupt vorhanden - des schmalen Streifens der Weichholzaue, verbleibt der Schwarzpappel nur ein sehr eingeschränkter Lebensraum entlang der Flüsse. Als Pionierbaumart kann die Schwarzpappel jedoch bei entsprechenden Bedingungen auch auf anderen Standorten wachsen, was für Populus-Arten in den nacheiszeitlichen Perioden nachgewiesen wurde (CWYNAR 1988). Die erfolgreiche Anpflanzung der Schwarzpappel als Straßenbaum in den Niederlanden (HEINZE 1998) und an Wasserläufen in England (WIENFIELD 1997) unterstreicht das. Diese Feststellung ist heute für Anstrengungen zur Erhaltung und Wiederansiedlung der Schwarzpappel wegen der nur noch selten vorhandenen Weichholzaue bedeutsam

Late Quaternary Changes in Silicate Utilisation and Upwelling Intensity off Peru – Insights from Silicon and Neodymium Isotopes

The Peruvian coastal upwelling region is characterised by one of the most pronounced oxygen minimum zones in the worlds ocean. The extension and strength of bottom water oxygen depletion has varied in the past as a function of surface water primary productivity and changes in circulation and upwelling intensity. So far, it has proven difficult to disentangle these influences. In this study the stable silicon isotope composition of diatoms (δ30Si) is used to reconstruct surface water silicic acid (Si(OH)4) utilisation during primary productivity. Radiogenic neodymium isotopes (εNd) from Fe-Mn coatings and benthic foraminifers were measured to trace water masses and their mixing, and the detrital fraction was analysed to provide information about sediment provenance, weathering inputs and their transport pathways. Besides the utilisation and water mass mixing effect, other processes such as remineralisation of the diatoms in the water column and in the sediment, influence the signal that is preserved. Here, the first systematic study of the dissolved δ30Si in the water column (δ30SiSi(OH)4) and in diatoms (δ30Siopal) from the underlying sediments in a coastal upwelling region is carried out to shed light onto the importance of these processes. The results show that the δ30SiSi(OH)4 signature strongly depends on upwelling strength, i.e. supply of new nutrients. Surface waters in the realm of intense upwelling are only weakly fractionated with respect to the subsurface source water signatures, whereas surface waters are more strongly fractionated where upwelling is less pronounced due to higher utilisation of the smaller amounts of available Si(OH)4. The δ30Siopal values of picked diatoms in the underlying sediments vary within the order of the expected fractionation between surface waters and diatoms and thus serve as a basis for the reliable use of the δ30Siopal as a proxy for past upwelling conditions. The sediments were also analysed for their εNd and compared to water column measurements from the same area. In general, all phases (seawater, Fe-Mn coatings, benthic foraminifers and detrital material) display a trend from more radiogenic values in the north towards less radiogenic values in the south. This is in agreement with the distribution of the signatures of the Andean hinterland rocks. This is most likely due to extensive exchange between sediments and the water column, which makes it difficult to use the εNd signatures obtained from Fe-Mn coatings or from benthic foraminiferal carbonate as a water mass tracer. Paleo-reconstructions show, that diatom-related productivity along the Peruvian upwelling area has varied greatly during the past 20 kyr. It was characterised by low fluxes of diatom opal during the last glacial and much higher values thereafter, in particular during the early and the latest Holocene. The combined approach of δ30Siopal and the radiogenic isotope composition (Nd, Sr) of Fe-Mn coatings of sediment particles and the detrital material itself reveal that this variability has been related to changes in Si(OH)4 utilisation, mostly controlled by the supply of iron and phosphate released from the shelf sediments via upwelling. During the glacial strong upwelling of subsurface waters with an overall low nutrient content significantly diminished primary productivity. During the early and late Holocene oceanographic conditions along the shelf were alternating between stronger and weaker upwelling. Especially the last 2,500 years were characterised by the largest variability of the system of the past 20,000 years, which coincided with the onset of modern El Nino-Southern Oscillation conditions in the Pacific. The late Holocene was also disrupted by major climatic anomalies, such as the Little Ice Age (LIA). Off Peru, a permanent mean southward migration of the Intertropical Convergence Zone (ITCZ) during the LIA strongly affected the trade wind-driven strength of the upwelling causing permanent El Nino-like conditions. The δ30Siopal show that productivity and nutrient utilisation were weak. The detrital sediment fraction was dominated by local riverine input of lithogenic material due to higher rainfall in the Andean hinterland. At the end of the LIA, the ITCZ shifted northward, which resulted in a pronounced increase in the strength of upwelling off Peru. Especially Si(OH)4 and Fe remineralisation from the shelf sediments was enhanced causing higher nutrient supply and diatom productivity. The radiogenic isotope record of the detrital shelf sediments indicates increased dust transport due to drier conditions under more persistent non-El Nino conditions. Comparison between δ30Siopal and bulk δ15N of organic matter suggests that surface water utilisation has been the predominant factor influencing both signals. The δ15N signature recorded in the sediment was not, as previously assumed, mainly influenced by subsurface water nitrate reduction processes

Intervention with Intimate Partner Violence: Application of Attachment and Personality Disorders

The goal of this study was to examine the influence attachment theory and personality disorders have on the clinical interventions currently used with individuals who have committed intimate partner violence. Qualitative interviews were conducted with four professionals currently working with IPV perpetrators in group or individual therapeutic settings. Six themes were developed: (a) Multiple Risk Factors of IPV, (b) Societal Views on Perpetration and Victimization, (c) Mental Health Informed Intervention Options for IPV, (d) Training or Educational Background Dictating Conceptual Framework, (e) Trauma and (f) Negative Connotations of Personality Disorders. The findings of this small exploratory study suggest that while mental health has become a major component of IPV intervention, more can be done to address some of the mental health underpinnings of IPV, and more research needs to be done to identify the most effective methods to support that area of focus

Intervention with Intimate Partner Violence: Application of Attachment and Personality Disorders

The goal of this study was to examine the influence attachment theory and personality disorders have on the clinical interventions currently used with individuals who have committed intimate partner violence. Qualitative interviews were conducted with four professionals currently working with IPV perpetrators in group or individual therapeutic settings. Six themes were developed: (a) Multiple Risk Factors of IPV, (b) Societal Views on Perpetration and Victimization, (c) Mental Health Informed Intervention Options for IPV, (d) Training or Educational Background Dictating Conceptual Framework, (e) Trauma and (f) Negative Connotations of Personality Disorders. The findings of this small exploratory study suggest that while mental health has become a major component of IPV intervention, more can be done to address some of the mental health underpinnings of IPV, and more research needs to be done to identify the most effective methods to support that area of focus

Training and accreditation of healthcare workers : are training guidelines meeting needs of the community?

Purpose of the researchThis paper presents an analysis of, and recommendations for, the training and accreditation of healthcare workers in CanadaThe significant cost of education and healthcare, as well as the current and ongoing national shortage of healthcare professionals, warrants a critical look at the educational training requirements of healthcare workers in Canada. This topic includes reviewing the historical background of training for a variety of healthcare professionals in Western cultures, the common philosophy of education trends for these workers, and the future directions for various professions, focusing specifically on Medical Radiation Technologists in Canada.Methods used The methodology applied to this research is that of critical analysis, utilizing the following critical skills as proposed by philosopher Bertrand Russell: “(i) the ability to form an opinion for oneself” (tasks of recognizing, listening and questioning), “(ii) the ability to find an impartial solution” (dealing with biases and detachment for beliefs, judging on merit of issues), and “(iii) the ability to identify and question assumptions” (emphasis on judgment, critical reflection and constructive rather than destructive doubt)(Hare, 2001, pp8-9). Recommendations regarding pre-service and continuing educational training for Medical Radiation Technologists in Canada will be proposed.Tied to any investigation of healthcare workers is a critical assessment of the healthcare system, as the needs of the community that is served by these professionals must be identified and successfully met. The literature review includes national statistics and summaries of health and lifestyle trends, as well as the trends for the education and training of healthcare workers.Results obtained/Significance of findingsReflective, critical assessment of the training and future trends of healthcare workers reveals that healthcare has undergone two major changes in focus: (1) healthcare as a business and (2) the holistic interdisciplinary trend of patient care.After investigating the trends of health care professionals’ training, and even though the arguments for degree as entry-to-practice are very strong on many levels, I don’t feel that I can conclude that the degree is the only option. If diploma training can adequately provide the basic theory and skills needed, additional skills and training, when required for a particular task, should be, and currently are, made available to the individual

Who Benefits from Training Courses in Germany? Monetary Returns to Non-formal Further Education on a Segmented Labour Market

While many advocate ‘lifelong learning’ as the ideal career model, its impact on workers’ lives is still partly unclear. Especially research on monetary returns to further education has yielded mixed evidence. I argue that a thorough assessment has to consider both the types of courses and the segmentation of labour markets. Using data from the German National Educational Panel Study, I test explanations of differing returns to non-formal further education in Germany, a country known for its highly segmented labour market. Results confirm that the returns to short non-formal training courses, which are the most common forms of further education in Germany, differ remarkably between types of courses and segments. Employer-mandated courses yield the highest returns, which is especially pronounced in internal labour markets. Furthermore, there are no returns on closed occupational labour markets. In occupations, where formal credentials are less important, returns to training are present. These results suggest that returns depend less on individual decisions to invest in training and more on the context. Hence, these findings go against human capital explanations and instead support implications of the Job Competition Model and Credentialism, which emphasize the importance of labour market structure