Prebiotic synthesis of sequential peptides on the Hadean beach by a molecular engine working with nitrogen oxides as energy sources

Addressing the still open question of the prebiotic origin of sequential macromolecules (peptides, nucleic acids) on the primitive Earth, we describe a molecular engine (the primary pump), which works at ambient temperature and continuously generates, elongates and complexifies sequential peptides. This new scenario is based on a cyclic reaction sequence, whose keystep is the activation of amino acids into their N‐carboxyanhydrides (NCA) through nitrosation by NOx. This process could have taken place on tidal beaches; it requires a buffered ocean, emerged land and a nitrosating atmosphere. With the help of geochemical studies and computer simulations of atmosphere photochemistry, we show that the primitive Earth during the Hadean may have satisfied all these requirements. © 2001 Society of Chemical Industry.     

Purification of a tumoral marker recognized by monoclonal antibody Po66 and associated with human lung squamous cell carcinoma

This paper reports on the production of tumor necrosis factor (TNF) and granulocyte macrophage colony-stimulating factor (GM-CSF) by cultured mononuclear adherent cells derived from bone marrow of 25 patients affected by myelodysplastic syndrome (MDS) of different FAB subtypes. Mean production of GM-CSF was much lower than in controls, without significant differences among different subtypes. Mean production of TNF was similar in MDS patients and in controls, but noteworthy differences were observed between patients with RA, RAEB and RAEB-t and patients with RARS and CMML. Growth of bone marrow granulocyte macrophage and erythroid progenitors did not correlate with TNF and GM-CSF production, although in MDS subtypes with higher GM-CSF levels, colony growth was slightly higher than in subtypes with lower GM-CSF production.     

Autonomic nervous system and subjective ratings of strain in air-traffic control

The paper is aimed at studying the perceived strain in professional air-traffic controllers both through self-evaluation and physiological indicators from the autonomic nervous system (ANS). The number of aircraft to be monitored was the main independent variable and could evolve at random within 1 and 10. Five ANS variables were recorded continuously in 25 participants while they handled real traffic: skin potential, skin conductance, skin blood flow, skin temperature and instantaneous heart rate. The tonic level of each physiological variable was averaged to match the times spent monitoring a constant number of aircraft. After the session, participants reacted in compliance with the NASA-TLX rating scale. Subjective ratings and physiological values were closely correlated to the number of aircraft, especially when data were standardized thus reducing inter-subjects differences in baseline levels. Results provide objective information to prevent air-traffic controllers from overloaded situations as well as to improve passengers’ safety.     

Hybrid genetic optimization and statistical model based approachfor the classification of shadow shapes in sonar imagery

We present an original statistical classification method using a deformable template model to separate natural objects from man-made objects in an image provided by a high resolution sonar. A prior knowledge of the manufactured object shadow shape is captured by a prototype template, along with a set of admissible linear transformations, to take into account the shape variability. Then, the classification problem is defined as a two-step process: 1) the detection problem of a region of interest in the input image is stated as the minimization of a cost function; and 2) the value of this function at convergence allows one to determine whether the desired object is present or not in the sonar image. The energy minimization problem is tackled using relaxation techniques. In this context, we compare the results obtained with a deterministic relaxation technique and two stochastic relaxation methods: simulated annealing and a hybrid genetic algorithm. This latter method has been successfully tested on real and synthetic sonar images, yielding very promising results     

Sonar image segmentation using an unsupervised hierarchical MRFmodel

This paper is concerned with hierarchical Markov random field (MRP) models and their application to sonar image segmentation. We present an original hierarchical segmentation procedure devoted to images given by a high-resolution sonar. The sonar image is segmented into two kinds of regions: shadow (corresponding to a lack of acoustic reverberation behind each object lying on the sea-bed) and sea-bottom reverberation. The proposed unsupervised scheme takes into account the variety of the laws in the distribution mixture of a sonar image, and it estimates both the parameters of noise distributions and the parameters of the Markovian prior. For the estimation step, we use an iterative technique which combines a maximum likelihood approach (for noise model parameters) with a least-squares method (for MRF-based prior). In order to model more precisely the local and global characteristics of image content at different scales, we introduce a hierarchical model involving a pyramidal label field. It combines coarse-to-fine causal interactions with a spatial neighborhood structure. This new method of segmentation, called the scale causal multigrid (SCM) algorithm, has been successfully applied to real sonar images and seems to be well suited to the segmentation of very noisy images. The experiments reported in this paper demonstrate that the discussed method performs better than other hierarchical schemes for sonar image segmentation.     

Autonomic nervous system responses correlate with mental rehearsal in volleyball training

The proliferative rate of a tumor has been considered predictive of its clinical course. We evaluated the expression of the proliferative marker Ki-67 and its relationship to survival, disease-free survival and other clinicopathologic variables in both stage I and stage II non-small cell lung cancer (NSCLC). A total of 260 patients with surgically resected stage I (n = 193), and II (n = 67) NSCLC with at least 5 years follow-up were identified. The median survival for patients with low expression of Ki-67 (< or = 25%) was 54 months, while for those with high expression (> 25%), it was 45 months (P = 0.1). The disease-free survival in patients with low expression of Ki-67 was 59 months while it was only 32 months for patients with high Ki-67 (P = 0.1). Out of 136 patients, 84 (62%) had both increased S-phase (> 8%) and high Ki-67 (P = 0.001). A total of 28 of 30 patients who had loss of antigen A had high expression of Ki-67 (93.3%) (P = 0.03). Ki-67 expression was also higher in squamous cell (54/63, 85.7%) compared to nonsquamous cell cancer (70/108, 64%) (P = 0.03). We also analyzed for the presence of symptoms with survival. The presence of symptoms was not found to be statistically significant, for overall survival (P = 0.33) or disease-free survival (P = 0.72). When individual symptoms were analyzed, the presence of cough was statistically significant for both overall and disease-free survival. The median survival was 39 months for patients with cough, and 57 months for patients without cough (P = 0.04). Multivariate analysis showed higher N and T stages, presence of cough and loss of antigen A, predicted for poorer overall survival. Higher N and T stages, loss of antigen A, presence of mucin and cough and increased expression of Ki-67 predicted decreased disease-free survival. Although we did not find a statistically significant difference between low and high Ki-67, there was a trend for a poorer overall and disease-free survival in patients with high Ki-67 expression. Larger studies may be needed to prove a statistically significant effect of Ki-67 on survival. Future studies should assess the potential prognostic significance of the presence of symptoms (particularly cough) in addition to clinical-pathologic variables (such as T and N stage) and biological markers in patients with early stage NSCLC.     

Functional results of the laparoscopic treatment of gastroesophageal reflux (followup greater than 2 years)

Adjuvant immunotherapy with interferons and/or interleukin 2 (IL-2) is widely used for advanced kidney cancer. However, the results are not satisfactory so far. The purpose of this study is to evaluate the inducible activity of lymphokine-activated killer (LAK) cells against autologous human renal cell carcinoma. The effect of interleukin 7 (IL-7) on IL-2-induced LAK activity was assessed by the autologous assay system which we have established. Peripheral blood lymphocytes from patients with renal cell carcinoma were stimulated with IL-2 and/or IL-7, and tested for antitumor activity against autologous renal cell carcinoma. In all 10 cases tested, IL-7 alone induced LAK activity. Moreover, IL-2-induced LAK activity was augmented by the concomitant addition of IL-7. Flow cytometry revealed an increase in IL-2-receptor-positive lymphocytes following incubation with IL-7. These results suggest that combination therapy using IL-2 and IL-7 may be a useful treatment for patients with advanced renal cell carcinoma.     

Clustering of polarization-encoded images

Polarization-encoded imaging consists of the distributed measurements of polarization parameters for each pixel of an image. We address clustering of multidimensional polarization-encoded images. The spatial coherence of polarization information is considered. Two methods of analysis are proposed: polarization contrast enhancement and a more-sophisticated image-processing algorithm based on a Markovian model. The proposed algorithms are applied and validated with two different Mueller images acquired by a fully polarimetric imaging system.