Power HBT reliability for space applications

High power HBT process developed by UMS for X-band application have been space evaluated under CNES and ESA funding.The reliability assessment plan features high temperatures storage tests,DC life-tests,RF step test stress,ESD and radiation tests.A set of evaluation test vehicles was defined for this purpose.Activation energy have been determined,failure rate calculations are in line with the space requirement

Computational Complexity of Iterated Maps on the Interval (Extended Abstract)

The exact computation of orbits of discrete dynamical systems on the interval is considered. Therefore, a multiple-precision floating point approach based on error analysis is chosen and a general algorithm is presented. The correctness of the algorithm is shown and the computational complexity is analyzed. As a main result, the computational complexity measure considered here is related to the Ljapunow exponent of the dynamical system under consideration

Lev Vigotski y George Mead. Una psicologia social de los procesos cognitivos

Wetensch. publicatieFaculteit der Sociale Wetenschappe

From coinductive proofs to exact real arithmetic: theory and applications

Based on a new coinductive characterization of continuous functions we extract certified programs for exact real number computation from constructive proofs. The extracted programs construct and combine exact real number algorithms with respect to the binary signed digit representation of real numbers. The data type corresponding to the coinductive definition of continuous functions consists of finitely branching non-wellfounded trees describing when the algorithm writes and reads digits. We discuss several examples including the extraction of programs for polynomials up to degree two and the definite integral of continuous maps

Substrate Binding Kinetics and its Role in the Cytochrome P450 Hydroxylation Sequence

The kinetics of the binding of type I and type II substrates to cytochrome P450LM has been investigated. Type I substrates are preferentially bound compared to type II compounds. The rate constants range between 103 and 105 [M-1 s-1], indicating possible interference with rate limiting steps. Substrates bind to the reduced cytochrome with considerably lower rate constants. The results are in favour of the sequential reaction mechanism. The solubilized enzyme preparation shows properties similar to the microsomal enzyme system

A Review of Cardiac Radioablation (CR) for Arrhythmias: Procedures, Technology, and Future Opportunities.

Purpose: Cardiac radioablation (CR), a new treatment for cardiac arrhythmias such as ventricular tachycardia and atrial fibrillation, has had promising clinical outcomes to date. There is consequent desire for rapid clinical adoption. However, CR presents unique challenges to radiation therapy, and it is paramount that clinical adoption be performed safely and effectively. Recent reviews comprehensively detail patient selection, clinical history, treatment outcomes, and treatment toxicities but only briefly mention the technical aspects of CR. To address this knowledge gap, this review collates currently available knowledge regarding CR technology choice and procedural details to help inform and guide clinics considering implementing their own CR program, to aid technique standardization, and to highlight areas that require further development or verification. Methods and materials: Original preclinical and clinical scientific articles that sufficiently detailed CR technical aspects, including pretreatment electrophysiology and imaging, motion analysis and management techniques, treatment planning, and/or treatment delivery, were identified within a comprehensive literature search. Results: Nineteen preclinical and 18 clinical scientific articles sufficiently detailed the technical aspects of CR treatment deliveries on live subjects. The technical aspects of these scientific articles were diverse: Preclinical treatments have been performed with brachytherapy, photons, protons, and carbon ions, and clinical treatments have been performed with photons using conventional, robotic, and magnetic resonance imaging guided systems. Other technical aspects demonstrated similar variability. Conclusions: This review summarizes the technical aspects and procedural details of preclinical and clinical CR treatment deliveries and highlights the complexity and current variability of CR. There is need for standardized procedural reporting to aid multicenter and multiplatform evaluation and potential for significant technological improvements in imaging, planning, delivery, and monitoring to maximize the clinical outcomes for selected patients with arrhythmia

Minimal selective concentrations of tetracycline in complex aquatic bacterial biofilms

Selection pressure generated by antibiotics released into the environment could enrich for antibiotic resistance genes and antibiotic resistant bacteria, thereby increasing the risk for transmission to humans and animals. Tetracyclines comprise an antibiotic class of great importance to both human and animal health. Accordingly, residues of tetracycline are commonly detected in aquatic environments. To assess if tetracycline pollution in aquatic environments promotes development of resistance, we determined minimal selective concentrations (MSCs) in biofilms of complex aquatic bacterial communities using both phenotypic and genotypic assays. Tetracycline significantly increased the relative abundance of resistant bacteria at 10 μg/L, while specific tet genes (tetA and tetG) increased significantly at the lowest concentration tested (1 μg/L). Taxonomic composition of the biofilm communities was altered with increasing tetracycline concentrations. Metagenomic analysis revealed a concurrent increase of several tet genes and a range of other genes providing resistance to different classes of antibiotics (e.g. cmlA, floR, sul1, and mphA), indicating potential for co-selection. Consequently, MSCs for the tet genes of ≤ 1 μg/L suggests that current exposure levels in e.g. sewage treatment plants could be sufficient to promote resistance. The methodology used here to assess MSCs could be applied in risk assessment of other antibiotics as well

Quantification of T- and B-cell immune receptor distribution diversity characterizes immune cell infiltration and lymphocyte heterogeneity in clear cell renal cell carcinoma

Immune-modulating systemic therapies are often used to treat advanced cancer such as metastatic clear cell renal cell carcinoma (ccRCC). Used alone, sequence-based biomarkers neither accurately capture patient dynamics nor the tumor immune microenvironment. To better understand the tumor ecology of this immune microenvironment, we quantified tumor infiltration across two distinct ccRCC patient tumor cohorts using complementarity determining region-3 (CDR3) sequence recovery counts in tumor-infiltrating lymphocytes and a generalized diversity index (GDI) for CDR3 sequence distributions. GDI can be understood as a curve over a continuum of diversity scales which allows sensitive characterization of distributions to capture sample richness, evenness, and subsampling uncertainty, along with other important metrics that characterize tumor heterogeneity. For example, richness quantified the total unique sequence count, while evenness quantified similarities across sequence frequencies. Significant differences in receptor sequence diversity across gender and race revealed that patients with larger and more clinically aggressive tumors had increased richness of recovered tumoral CDR3 sequences, specifically in those from T-cell receptor alpha and B-cell immunoglobulin lambda light chain. The GDI inflection point (IP) allowed for a novel and robust measure of distribution evenness. High IP values associated with improved overall survival, suggesting that normal-like sequence distributions lead to better outcomes. These results propose a new quantitative tool that can be used to better characterize patient-specific differences related to immune cell infiltration, and to identify unique characteristics of tumor-infiltrating lymphocyte heterogeneity in ccRCC and other malignancies