Performance analysis of a miniature turbine generator for intracorporeal energy harvesting

Replacement intervals of implantable medical devices are commonly dictated by battery life. Therefore, intracorporeal energy harvesting has the potential to reduce the number of surgical interventions by extending the life cycle of active devices. Given the accumulated experience with intravascular devices such as stents, heart valves, and cardiac assist devices, the idea to harvest a small fraction of the hydraulic energy available in the cardiovascular circulation is revisited. The aim of this article is to explore the technical feasibility of harvesting 1 mW electric power using a miniature hydrodynamic turbine powered by about 1% of the cardiac output flow in a peripheral artery. To this end, numerical modelling of the fluid mechanics and experimental verification of the overall performance of a 1:1 scale friction turbine are performed in vitro. The numerical flow model is validated for a range of turbine configurations and flow conditions (up to 250 mL/min) in terms of hydromechanic efficiency; up to 15% could be achieved with the nonoptimized configurations of the study. Although this article does not entail the clinical feasibility of intravascular turbines in terms of hemocompatibility and impact on the circulatory system, the numerical model does provide first estimates of the mechanical shear forces relevant to blood trauma and platelet activation. It is concluded that the time-integrated shear stress exposure is significantly lower than in cardiac assist devices due to lower flow velocities and predominantly laminar flow.

Reversal of gender differences in Educational Attainment – historical analysis of the West German Case

Background information: During the late 1970s and the early 1980s, West Germany witnessed a reversal of gender differences in educational attainment, as females began to outperform males. Purpose: The main objective was to analyse which processes were behind the reversal of gender differences in educational attainment after 1945. The theoretical reflections and empirical evidence presented for the US context by DiPrete and Buchmann (Gender-specific trends in the value of education and the emerging gender gap in college completion, Demography 43: 1–24, 2006) and Buchmann, DiPrete, and McDaniel (Gender inequalities in education, Annual Review of Sociology 34: 319–37, 2008) are considered and applied to the West German context. It is suggested that the reversal of gender differences is a consequence of the change in female educational decisions, which are mainly related to labour market opportunities and not, as sometimes assumed, a consequence of a ‘boy’s crisis’. Sample: Several databases, such as the German General Social Survey, the German Socio-economic Panel and the German Life History Study, are employed for the longitudinal analysis of the educational and occupational careers of birth cohorts born in the twentieth century. Design and methods: Changing patterns of eligibility for university studies are analysed for successive birth cohorts and gender. Binary logistic regressions are employed for the statistical modelling of the individuals’ achievement, educational decision and likelihood for social mobility – reporting average marginal effects (AME). Results: The empirical results suggest that women’s better school achievement being constant across cohorts does not contribute to the explanation of the reversal of gender differences in higher education attainment, but the increase of benefits for higher education explains the changing educational decisions of women regarding their transition to higher education. Conclusions: The outperformance of females compared with males in higher education might have been initialised by several social changes, including the expansion of public employment, the growing demand for highly qualified female workers in welfare and service areas, the increasing returns of women’s increased education and training, and the improved opportunities for combining family and work outside the home. The historical data show that, in terms of (married) women’s increased labour market opportunities and female life-cycle labour force participation, the raising rates of women’s enrolment in higher education were – among other reasons – partly explained by their rising access to service class positions across birth cohorts, and the rise of their educational returns in terms of wages and long-term employment.

The applicability of non-local LCI data for LCA

This study evaluated how applicable European Life Cycle Inventory (LCI) data are to assessing the environmental impacts of the life cycle of Brazilian triple superphosphate (TSP). The LCI data used for the comparison were local Brazilian LCI data, European LCI data in its original version from the ecoinvent database and a modified version of the European LCI data, which had been adapted to better account for the Brazilian situation. We compared the three established datasets at the level of the inventory as well as for their environmental impacts, i.e. at the level of Life Cycle Environmental Assessment (LCIA). The analysis showed that the European LCIs (both the original and the modified ones) considered a broader spectrum of background processes and environmental flows (inputs and outputs). Nevertheless, TSP production had in all three cases similar values for the consumption of the main raw materials. The LCIA results obtained for the datasets showed important differences as well. Therefore we concluded that the European data in general lead to much higher environmental impacts than the Brazilian data. The differences between the LCIA results obtained with the Brazilian and the European data can be basically explained by the methodological differences underlying the data. The small differences at the LCI level for selected inputs and outputs between the Brazilian and the European LCIs from ecoinvent indicate that the latter can be regarded as applicable for characterizing the Brazilian TSP.

Capturing How Objects Flow At Runtime

Most of today's dynamic analysis approaches are based on method traces. However, in the case of object-orientation understanding program execution by analyzing method traces is complicated because the behavior of a program depends on the sharing and the transfer of object references (aliasing). We argue that trace-based dynamic analysis is at a too low level of abstraction for object-oriented systems. We propose a new approach that captures the life cycle of objects by explicitly taking into account object aliasing and how aliases propagate during the execution of the program. In this paper, we present in detail our new meta-model and discuss future tracks opened by it.

Cloning and characterization of a novel zinc finger protein (rZFP96) in the rat corpus luteum

The corpus luteum (CL) is a temporary organ involved in the maintenance of pregnancy. In the course of its life-cycle, the CL undergoes two distinct and consecutive processes for its inevitable removal through apoptosis: functional and structural luteolysis. We isolated a gene encoding for a novel rat zinc finger protein (ZFP), named rat ZFP96 (rZFP96) from an ovarian lambda cDNA library. Sequence analysis revealed close sequence and structural similarity to mouse ZFP96 and human zinc finger protein 305 (ZNF305). Quantitative reverse transcription-polymerase chain reaction analysis revealed a positive correlation with the end of pregnancy, that is, the onset of structural luteolysis of the CL. Messenger RNA levels increased 3-fold (P < 0.01) between days 13 and 22 of pregnancy and 8-fold (P < 0.01) between day 13 of pregnancy and day 1 post-partum. In addition, we detected rZFP96 expression in mammary, placenta, heart, kidney and skeletal muscle. Sequence analysis predicted that rZFP96 has a high probability of localizing to the nuclear compartment. The presence of both a perfect consensus TGEKP linker sequence between zinc fingers 2 and 3 as well as several similar sequences between the other zinc fingers suggests physical interaction with DNA. Speculatively, rZFP96 may therefore function as a transcription factor, switching-off pro-survival genes and/or upregulating pro-apoptotic genes and thereby contributing to the demise of the CL.

Mitochondrial Outer Membrane Proteome of Trypanosoma brucei Reveals Novel Factors Required to Maintain Mitochondrial Morphology

Trypanosoma brucei is a unicellular parasite that causes devastating diseases in humans and animals. It diverged from most other eukaryotes very early in evolution and, as a consequence, has an unusual mitochondrial biology. Moreover, mitochondrial functions and morphology are highly regulated throughout the life cycle of the parasite. The outer mitochondrial membrane defines the boundary of the organelle. Its properties are therefore key for understanding how the cytosol and mitochondria communicate and how the organelle is integrated into the metabolism of the whole cell. We have purified the mitochondrial outer membrane of T. brucei and characterized its proteome using label-free quantitative mass spectrometry for protein abundance profiling in combination with statistical analysis. Our results show that the trypanosomal outer membrane proteome consists of 82 proteins, two-thirds of which have never been associated with mitochondria before. 40 proteins share homology with proteins of known functions. The function of 42 proteins, 33 of which are specific to trypanosomatids, remains unknown. 11 proteins are essential for the disease-causing bloodstream form of T. brucei and therefore may be exploited as novel drug targets. A comparison with the outer membrane proteome of yeast defines a set of 17 common proteins that are likely present in the mitochondrial outer membrane of all eukaryotes. Known factors involved in the regulation of mitochondrial morphology are virtually absent in T. brucei. Interestingly, RNAi-mediated ablation of three outer membrane proteins of unknown function resulted in a collapse of the network-like mitochondrion of procyclic cells and for the first time identified factors that control mitochondrial shape in T. brucei.

Insights into the regulation of GPEET procyclin during differentiation from early to late procyclic forms of Trypanosoma brucei.

The procyclic form of Trypanosoma brucei colonises the gut of its insect vector, the tsetse fly. GPEET and EP procyclins constitute the parasite's surface coat at this stage of the life cycle, and the presence or absence of GPEET distinguishes between early and late procyclic forms, respectively. Differentiation from early to late procyclic forms in vivo occurs in the fly midgut and can be mimicked in culture. Our analysis of this transition in vitro delivered new insights into the process of GPEET repression. First, we could show that parasites followed a concrete sequence of events upon triggering differentiation: after undergoing an initial growth arrest, cells lost GPEET protein, and finally late procyclic forms resumed proliferation. Second, we determined the stability of both GPEET and EP mRNA during differentiation. GPEET mRNA is exceptionally stable in early procyclic forms, with a half-life >6h. The GPEET mRNA detected in late procyclic form cultures is a mixture of transcripts from both bona fide late procyclic forms and GPEET-positive 'laggard' parasites present in these cultures. However, its stability was clearly reduced during differentiation and in late procyclic form cultures. Alternatively processed GPEET transcripts were enriched in samples from late procyclic forms, suggesting that altered mRNA processing might contribute to repression of GPEET in this developmental stage. In addition, we detected GPEET transcripts with non-templated oligo(U) tails that were enriched in late procyclic forms. To the best of our knowledge, this is the first study reporting a uridylyl-tailed, nuclear-encoded mRNA species in trypanosomatids or any other protozoa.

IMILAST: A community effort to intercompare extratropical cyclone detection and tracking algorithms: assessing method-related uncertainties

The variability of results from different automated methods of detection and tracking of extratropical cyclones is assessed in order to identify uncertainties related to the choice of method. Fifteen international teams applied their own algorithms to the same dataset - the period 1989-2009 of interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERAInterim) data. This experiment is part of the community project Intercomparison of Mid Latitude Storm Diagnostics (IMILAST; see www.proclim.ch/imilast/index.html). The spread of results for cyclone frequency, intensity, life cycle, and track location is presented to illustrate the impact of using different methods. Globally, methods agree well for geographical distribution in large oceanic regions, interannual variability of cyclone numbers, geographical patterns of strong trends, and distribution shape for many life cycle characteristics. In contrast, the largest disparities exist for the total numbers of cyclones, the detection of weak cyclones, and distribution in some densely populated regions. Consistency between methods is better for strong cyclones than for shallow ones. Two case studies of relatively large, intense cyclones reveal that the identification of the most intense part of the life cycle of these events is robust between methods, but considerable differences exist during the development and the dissolution phases.

BPM software and process modelling languages in practice

IT has turned out to be a key factor for the purposes of gaining maturity in Business Process Management (BPM). This book presents a worldwide investigation that was conducted among companies from the ‘Forbes Global 2000’ list to explore the current usage of software throughout the BPM life cycle and to identify the companies’ requirements concerning process modelling. The responses from 130 companies indicate that, at the present time, it is mainly software for process description and analysis that is required, while process execution is supported by general software such as databases, ERP systems and office tools. The resulting complex system landscapes give rise to distinct requirements for BPM software, while the process modelling requirements can be equally satisfied by the most common languages (BPMN, UML, EPC).

A conserved mitochondrial outer membrane protein mediates kDNA maintenace in Trypanosoma brucei

Kinetoplastids are defined by the unique organization of their mitochondrial DNA (kDNA). It forms a highly concatenated DNA network that is linked to the basal body of the flagellum by the tripartite attachment complex (TAC). The TAC encompasses intra and extramitochondrial filaments and a highly differentiated region of the two mitochondrial membranes. Here we identify and characterize a mitochondrial outer membrane protein of Trypanosoma brucei that is predominantly localized in the TAC. The protein is essential for growth in both life cycle stages. Immunofluorescence shows that ablation of the protein does not affect kDNA replication but abolishes the segregation of the replicated kDNA network causing rapid loss of kDNA. Besides its role in kDNA maintenance in vivo and in vitro experiments show that the protein is involved in mitochondrial protein import and that it interacts with a recently discovered protein import factor. RNAi experiments in a T. brucei cell line in which the kDNA is dispensable suggest that the essential function is linked to kDNA maintenance. Bioinformatic analysis shows that the studied outer membrane protein has beta-barrel topology and that it belongs to the mitochondrial porin family comprising VDAC, Tom40 and Mdm10. Interestingly, Mdm10 has sofar only been found in yeast. Ist function in protein import and mitochondrial DNA maintenance suggests that the protein in our study is the functional homologue of Mdm10. Thus, the TAC – a defining structure of Kinetoplastids – contains a conserved protein which in yeast and trypanosomes performs the same function. Our study therefore provides an example that trypanosomal biology, rather than being unique, often simply represents a more extreme manifestation of a conserved biological concept.

A conserved mitochondrial outer membrane protein mediates kDNA maintenace in Trypanosoma brucei

Kinetoplastids are defined by the unique organization of their mitochondrial DNA (kDNA). It forms a highly concatenated DNA network that is linked to the basal body of the flagellum by the tripartite attachment complex (TAC). The TAC encompasses intra and extramitochondrial filaments and a highly differentiated region of the two mitochondrial membranes. Here we identify and characterize a mitochondrial outer membrane protein of Trypanosoma brucei that is predominantly localized in the TAC. The protein is essential for growth in both life cycle stages. Immunofluorescence shows that ablation of the protein does not affect kDNA replication but abolishes the segregation of the replicated kDNA network causing rapid loss of kDNA. Besides its role in kDNA maintenance in vivo and in vitro experiments show that the protein is involved in mitochondrial protein import and that it interacts with a recently discovered protein import factor. RNAi experiments in a T. brucei cell line in which the kDNA is dispensable suggest that the essential function is linked to kDNA maintenance. Bioinformatic analysis shows that the studied outer membrane protein has beta-barrel topology and that it belongs to the mitochondrial porin family comprising VDAC, Tom40 and Mdm10. Interestingly, Mdm10 has so far only been found in yeast. Its function in protein import and mitochondrial DNA maintenance suggests that the protein in our study is the functional homologue of Mdm10. Thus, the TAC – a defining structure of Kinetoplastids – contains a conserved protein which in yeast and trypanosomes performs the same function. Our study therefore provides an example that trypanosomal biology, rather than being unique, often simply represents a more extreme manifestation of a conserved biological concept.

On the Co-Occurrence of Warm Conveyor Belt Outflows and PV Streamers*

The co-occurrence of warm conveyor belts (WCBs), strongly ascending moist airstreams in extratropical cyclones, and stratospheric potential vorticity (PV) streamers, indicators for breaking Rossby waves on the tropopause, is investigated for a 21-yr period in the Northern Hemisphere using Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) data. WCB outflows and PV streamers are respectively identified as two- and three-dimensional objects and tracked during their life cycle. PV streamers are more frequent than WCB outflows and nearly 15% of all PV streamers co-occur with WCBs during their life cycle, whereas about 60% of all WCB outflows co-occur with PV streamers. Co-occurrences are most frequent over the North Atlantic and North Pacific in spring and winter. WCB outflows are often located upstream of the PV streamers and form earlier, indicating the importance of diabatic processes for downstream Rossby wave breaking. Less frequently, PV streamers occur first, leading to the formation of new WCBs.

Quantifying the turnover of transcriptional subclasses of HIV-1-infected cells

HIV-1-infected cells in peripheral blood can be grouped into different transcriptional subclasses. Quantifying the turnover of these cellular subclasses can provide important insights into the viral life cycle and the generation and maintenance of latently infected cells. We used previously published data from five patients chronically infected with HIV-1 that initiated combination antiretroviral therapy (cART). Patient-matched PCR for unspliced and multiply spliced viral RNAs combined with limiting dilution analysis provided measurements of transcriptional profiles at the single cell level. Furthermore, measurement of intracellular transcripts and extracellular virion-enclosed HIV-1 RNA allowed us to distinguish productive from non-productive cells. We developed a mathematical model describing the dynamics of plasma virus and the transcriptional subclasses of HIV-1-infected cells. Fitting the model to the data allowed us to better understand the phenotype of different transcriptional subclasses and their contribution to the overall turnover of HIV-1 before and during cART. The average number of virus-producing cells in peripheral blood is small during chronic infection. We find that a substantial fraction of cells can become defectively infected. Assuming that the infection is homogenous throughout the body, we estimate an average in vivo viral burst size on the order of 104 virions per cell. Our study provides novel quantitative insights into the turnover and development of different subclasses of HIV-1-infected cells, and indicates that cells containing solely unspliced viral RNA are a good marker for viral latency. The model illustrates how the pool of latently infected cells becomes rapidly established during the first months of acute infection and continues to increase slowly during the first years of chronic infection. Having a detailed understanding of this process will be useful for the evaluation of viral eradication strategies that aim to deplete the latent reservoir of HIV-1.

Functional proteomics and biochemsitry: working together to unravel mitochondrial phenomena of African trypansomes

Eukaryotic cells are compartmentalized into membrane-bound organelles in order to provide sheltered reaction rooms for various specific processes. Organelles are not randomly distributed in a cell or operate isolated from each other. At the contrary — some organelles are closely linked and their functions are tightly orchestrated. The most well-known example of two such organelles acting in concert are the ER and the mitochondrion that work together in order to coordinate cellular lipid biosynthesis, maintain Ca2+-homeostasis, regulate mitochondrial division and control mitochondrial/ER shape as well as to synchronize the movement of these organelles within a cell. To study the mitochondrion and its interface to the ER requires a simplified mitochondrial system. African trypanosomes represent such a system. The unicellular parasite that causes devastating diseases in humans and animals has only one large mitochondrion that does not undergo fission/fusion events except for the context of cell division. Moreover, mitochondrial functions and morphology are highly regulated throughout the life cycle of the protozoan. Central to the understanding of how mitochondria control their morphology, communicate with their surroundings and manage exchange of metabolites and transport of biopolymers (proteins, RNAs) is the mitochondrial outer membrane (MOM), as the MOM defines the boundary of the organelle. Recently, we have purified the MOM of T. brucei and characterized its proteome using label-free quantitative mass spectrometry for protein abundance profiling in combination with statistical analysis. Our results show that the trypanosomal MOM proteome consists of 82 proteins, two thirds of which have never been associated with mitochondria before. Among these, we identified novel factors required to regulate mitochondrial morphology and the long-elusive protein import machinery of T. brucei. A comparison with the MOM proteome of yeast defines a set of 17 common proteins that are likely present in the mitochondrial outer membrane of all eukaryotes. One of these is the Miro-GTPase Gem1. In yeast, this Ca2+-EF-Hand containing polypeptide is thought to be involved in a protein complex that physically tethers the mitochondrion to the ER. Interestingly, a putative tethering complex in mammalian cells was linked to the mitochondrial fusion/fission machinery. Thus, the concept of a protein complex-mediated connection seems to be a general and conserved feature. We are currently investigating, if such a protein complex exists in T. brucei and if the trypanosomal Gem1 protein is involved. This ER-subdomain associated with mitochondria has been termed mitochondria-associated ER-membranes or MAM. The MAM has recently been implicated to play a key role in Alzheimer’s disease. It is therefore of broad and general interest to establish other eukaryotic model systems in order to investigate the MAM-MOM connection in more detail.

Heterogeneity in the Relationship between Happiness and Age: Evidence from the German Socio-Economic Panel

This paper studies the evolution of life satisfaction over the life course in Germany. It clarifies the causal interpretation of the econometric model by discussing the choice of control variables and the underidentification between age, cohort and time effects. The empirical part analyzes the distribution of life satisfaction over the life course at the aggregated, subgroup and individual level. To the findings: On average, life satisfaction is mildly decreasing up to age 55 followed by a hump shape with a maximum at 70. The analysis at the lower levels suggests that people differ in their life satisfaction trends, whereas the hump shape after age 55 is robust. No important differences between men and women are found. In contrast, education groups differ in their trends: highly educated people become happier over the life cycle, where life satisfaction decreases for less-educated people.