2,788 research outputs found
Thermodynamik – grundlegende Einsichten für ein Verständnis von Umweltproblemen
In this paper, we present a way that allows to make fundamental statements about how economic action entails harmful effects on the environment. These effects are due to natural scientific reasons and are particularly present in the industrialised economy. The starting point of our considerations is that every economic action requires energy, of which many different forms exist. Taking all of these forms into account, heat energy has a particular significance, because other forms of energy can never appear in isolation, but only conjointly with heat energy. For this reason, the branch of physics that deals primarily with energy is called thermodynamics. The study of thermodynamics yields the central link between economic activity and its environmental impact. Understanding basic insights of thermodynamics enables decision-makers in environmental policy to understand the nature of environmental problems and to develop possible solutions. First, we deal with the connection between physical work and heat. Then we explain the two main Laws of Thermodynamics and go into detail about the concept of entropy. We use Boltzmann's approach of the degree of order to give an illustration of the entropy concept. We then turn to the consideration of thermodynamics in economics, first provided by Georgescu-Roegen in 1971. Following this we explain the importance of thermodynamics for environmental policy. We conclude with a summary.
In diesem Beitrag stellen wir einen Weg vor, der es erlaubt, grundsätzliche Aussagen darüber zu treffen, dass wirtschaftliches Handeln schädliche Auswirkungen auf die Umwelt mit sich bringt. Diese Auswirkungen sind naturwissenschaftlich bedingt und treten insbesondere in der industrialisierten Wirtschaft auf. Ausgangspunkt unserer Überlegungen ist, dass jedes wirtschaftliche Handeln Energie benötigt, von der es viele verschiedene Formen gibt. Unter Berücksichtigung all dieser Formen kommt der Wärmeenergie eine besondere Bedeutung zu, da andere Energieformen nie isoliert, sondern nur in Verbindung mit der Wärmeenergie auftreten können. Aus diesem Grund wird der Zweig der Physik, der sich hauptsächlich mit Energie beschäftigt, Thermodynamik genannt. Das Studium der Thermodynamik stellt die zentrale Verbindung zwischen wirtschaftlicher Tätigkeit und ihren Auswirkungen auf die Umwelt her. Das Verständnis grundlegender Erkenntnisse der Thermodynamik ermöglicht es Entscheidungsträgern in der Umweltpolitik, das Entstehen von Umweltproblemen zu verstehen und mögliche Lösungen zu entwickeln. Zunächst befassen wir uns mit dem Zusammenhang zwischen physikalischer Arbeit und Wärme. Dann erläutern wir die beiden Hauptsätze der Thermodynamik und gehen ausführlich auf das Konzept der Entropie ein. Zur Veranschaulichung des Entropiekonzepts verwenden wir den Boltzmann'schen Ansatz des Ordnungsgrades. Anschließend wenden wir uns der Betrachtung der Thermodynamik in den Wirtschaftswissenschaften zu, die erstmals von Georgescu-Roegen im Jahr 1971 vorgelegt wurde. Anschließend erläutern wir die Bedeutung der Thermodynamik für die Umweltpolitik. Wir schließen mit einer Zusammenfassung
Allergens of the urushiol family promote mitochondrial dysfunction by inhibiting the electron transport at the level of cytochromes b and chemically modify cytochrome c1
BACKGROUND: Urushiols are pro-electrophilic haptens that cause severe contact dermatitis mediated by CD8+ effector T-cells and downregulated by CD4+ T-cells. However, the molecular mechanism by which urushiols stimulate innate immunity in the initial stages of this allergic reaction is poorly understood. Here we explore the sub-cellular mechanisms by which urushiols initiate the allergic response. RESULTS: Electron microscopy observations of mouse ears exposed to litreol (3-n-pentadecyl-10-enyl-catechol]) showed keratinocytes containing swollen mitochondria with round electron-dense inclusion bodies in the matrix. Biochemical analyses of sub-mitochondrial fractions revealed an inhibitory effect of urushiols on electron flow through the mitochondrial respiratory chain, which requires both the aliphatic and catecholic moieties of these allergens. Moreover, urushiols extracted from poison ivy/oak (mixtures of 3-n-pentadecyl-8,11,13 enyl/3-n-heptadecyl-8,11 enyl catechol) exerted a higher inhibitory effect on mitochondrial respiration than did pentadecyl catechol or litreol, indicating that the higher number of unsaturations in the aliphatic chain, stronger the allergenicity of urushiols. Furthermore, the analysis of radioactive proteins isolated from mitochondria incubated with 3H-litreol, indicated that this urushiol was bound to cytochrome c1. According to the proximity of cytochromes c1 and b, functional evidence indicated the site of electron flow inhibition was within complex III, in between cytochromes bL (cyt b566) and bH (cyt b562). CONCLUSION: Our data provide functional and molecular evidence indicating that the interruption of the mitochondrial electron transport chain constitutes an important mechanism by which urushiols initiates the allergic response. Thus, mitochondria may constitute a source of cellular targets for generating neoantigens involved in the T-cell mediated allergy induced by urushiols
A new displacement-based approach to calculate stress intensity factors with the boundary element method
The analysis of cracked brittle mechanical components considering linear elastic fracture mechanics is usually reduced to the evaluation of stress intensity factors (SIFs). The SIF calculation can be carried out experimentally, theoretically or numerically. Each methodology has its own advantages but the use of numerical methods has be-come very popular. Several schemes for numerical SIF calculations have been developed, the J-integral method being one of the most widely used because of its energy-like formulation. Additionally, some variations of the J-integral method, such as displacement-based methods, are also becoming popular due to their simplicity. In this work, a simple displacement-based scheme is proposed to calculate SIFs, and its performance is compared with contour integrals. These schemes are all implemented with the Boundary Element Method (BEM) in order to exploit its advantages in crack growth modelling. Some simple examples are solved with the BEM and the calculated SIF values are compared against available solutions, showing good agreement between the different schemes
Transcutaneous electrical nerve stimulation for advanced cancer pain inpatients in specialist palliative care—a blinded, randomized, sham-controlled pilot cross-over trial
Purpose
Transcutaneous electrical nerve stimulation (TENS) is a treatment option for cancer pain, but the evidence is inconclusive. We aimed to evaluate the efficacy and safety of TENS.
Methods
A blinded, randomized, sham-controlled pilot cross-over trial (NCT02655289) was conducted on an inpatient specialist palliative care ward. We included adult inpatients with cancer pain ≥ 3 on an 11-point numerical rating scale (NRS). Intensity-modulated high TENS (IMT) was compared with placebo TENS (PBT). Patients used both modes according to their preferred application scheme during 24 h with a 24-h washout phase. The primary outcome was change in average pain intensity on the NRS during the preceding 24 h. Responders were patients with at least a “slight improvement.”
Results
Of 632 patients screened, 25 were randomized (sequence IMT-PBT = 13 and PBT-IMT = 12). Finally, 11 patients in IMT-PBT and 9 in PBT-IMT completed the study (N = 20). The primary outcome did not differ between groups (IMT minus PBT: − 0.2, 95% confidence interval − 0.9 to 0.6). However, responder rates were higher in IMT (17/20 [85%] vs. 10/20 [50%], p = 0.0428). Two patients experienced an uncomfortable feeling caused by the current, one after IMT and one after PBT. Seven patients (35%) desired a TENS prescription. Women and patients with incident pain were most likely to benefit from TENS.
Conclusion
TENS was safe, but IMT was unlikely to offer more analgesic effects than PBT. Even though many patients desired a TENS prescription, 50% still reported at least “slight pain relief” from PBT. Differences for gender and incident pain aspects demand future trials
Transient Increase in Intrathoracic Pressure as a Contributing Factor to Cardioembolic Stroke
Effect of large-scale intermittency and mean shear on scaling-range exponents in a turbulent jet
The present study investigates the combined impact of the intermittency associated with the turbulent-nonturbulent interface and the mean shear rate in an axisymmetric jet on the structure of turbulence in the scaling range, where the spectrum exhibits a power-law behavior. Second-order structure functions, autocorrelations of the dissipation rate, and spectra of both the longitudinal velocity fluctuation and the passive temperature fluctuation are measured at a distance of 40 diameter downstream from the nozzle exit. All the scaling range exponents are influenced by the large-scale intermittency and the mean shear. The scalar fluctuation is much more sensitive to the variation in large-scale intermittency than the velocity fluctuation.J. Mi and R. A. Antoni
Surface electrons at plasma walls
In this chapter we introduce a microscopic modelling of the surplus electrons
on the plasma wall which complements the classical description of the plasma
sheath. First we introduce a model for the electron surface layer to study the
quasistationary electron distribution and the potential at an unbiased plasma
wall. Then we calculate sticking coefficients and desorption times for electron
trapping in the image states. Finally we study how surplus electrons affect
light scattering and how charge signatures offer the possibility of a novel
charge measurement for dust grains.Comment: To appear in Complex Plasmas: Scientific Challenges and Technological
Opportunities, Editors: M. Bonitz, K. Becker, J. Lopez and H. Thomse
Retroperitoneal hematoma after coil embolization of cerebral aneurysm -A case report-
We present the case of a 57-year-old man who developed retroperitoneal hemorrhage due to unintentional arterial puncture during femoral artery cannulation for Guglielmi detachable coil embolization. On emergence from anesthesia, he developed severe hypotension. Computed tomographic angiogram of the abdomen showed retroperitoneal hematomas around the urinary bladder, liver, and spleen. Because femoral artery cannulation is a common procedure for intravascular embolization in neuroradiologic procedures, Clinicians should be aware of the development of severe hematomas as a consequence of femoral artery puncture
Proposed Definitions of T Cell-Mediated Rejection and Tubulointerstitial Inflammation as Clinical Trial Endpoints in Kidney Transplantation
The diagnosis of acute T cell-mediated rejection (aTCMR) after kidney transplantation has considerable relevance for research purposes. Its definition is primarily based on tubulointerstitial inflammation and has changed little over time; aTCMR is therefore a suitable parameter for longitudinal data comparisons. In addition, because aTCMR is managed with antirejection therapies that carry additional risks, anxieties, and costs, it is a clinically meaningful endpoint for studies. This paper reviews the history and classifications of TCMR and characterizes its potential role in clinical trials: a role that largely depends on the nature of the biopsy taken (indication vs protocol), the level of inflammation observed (e.g., borderline changes vs full TCMR), concomitant chronic lesions (chronic active TCMR), and the therapeutic intervention planned. There is ongoing variability-and ambiguity-in clinical monitoring and management of TCMR. More research, to investigate the clinical relevance of borderline changes (especially in protocol biopsies) and effective therapeutic strategies that improve graft survival rates with minimal patient morbidity, is urgently required. The present paper was developed from documentation produced by the European Society for Organ Transplantation (ESOT) as part of a Broad Scientific Advice request that ESOT submitted to the European Medicines Agency for discussion in 2020. This paper proposes to move toward refined definitions of aTCMR and borderline changes to be included as primary endpoints in clinical trials of kidney transplantation.Copyright © 2022 Seron, Rabant, Becker, Roufosse, Bellini, Böhmig, Budde, Diekmann, Glotz, Hilbrands, Loupy, Oberbauer, Pengel, Schneeberger and Naesens
Proposed Definitions of Antibody-Mediated Rejection for Use as a Clinical Trial Endpoint in Kidney Transplantation
Antibody-mediated rejection (AMR) is caused by antibodies that recognize donor human leukocyte antigen (HLA) or other targets. As knowledge of AMR pathophysiology has increased, a combination of factors is necessary to confirm the diagnosis and phenotype. However, frequent modifications to the AMR definition have made it difficult to compare data and evaluate associations between AMR and graft outcome. The present paper was developed following a Broad Scientific Advice request from the European Society for Organ Transplantation (ESOT) to the European Medicines Agency (EMA), which explored whether updating guidelines on clinical trial endpoints would encourage innovations in kidney transplantation research. ESOT considers that an AMR diagnosis must be based on a combination of histopathological factors and presence of donor-specific HLA antibodies in the recipient. Evidence for associations between individual features of AMR and impaired graft outcome is noted for microvascular inflammation scores ≥2 and glomerular basement membrane splitting of >10% of the entire tuft in the most severely affected glomerulus. Together, these should form the basis for AMR-related endpoints in clinical trials of kidney transplantation, although modifications and restrictions to the Banff diagnostic definition of AMR are proposed for this purpose. The EMA provided recommendations based on this Broad Scientific Advice request in December 2020; further discussion, and consensus on the restricted definition of the AMR endpoint, is required.Copyright © 2022 Roufosse, Becker, Rabant, Seron, Bellini, Böhmig, Budde, Diekmann, Glotz, Hilbrands, Loupy, Oberbauer, Pengel, Schneeberger and Naesens
- …