A Bayesian paradox and its impact on the GUM approach to uncertainty

The paper presents ideas and observations about the use of the frequentist and the Bayesian approach to estimation and uncertainty. The merits and the pitfalls of the Bayesian approach, compared with the frequentist one, are illustrated using a simple example, which gives rise to an instructive paradox. The impact of the paradox on the GUM approach to uncertainty prescribed in Supplement 1 is highlighted and discussed.     

A new real-time shape acquisition with a laser scanner: first test results

The first results of a new method for real-time shape acquisition with a laser scanner are presented. The new method is essentially based on the use of a laser beam and a web-cam. A digital filter parameters identification was studied for the laser line detection in the image. After this, a model for the reconstruction in real-time of the laser line in the space was developed. The first test rig was just conceived to validate the method; hence, no high resolution cameras were adopted. Nevertheless, the tests have showed encouraging results.     

Coexpression of IL-6 and soluble IL-6R causes nodular regenerative hyperplasia and adenomas of the liver

Studies with tumor necrosis factor p55 receptor- and interleukin-6 (IL-6)-deficient mice have shown that IL-6 is required for hepatocyte proliferation and reconstitution of the liver mass after partial hepatectomy. The biological activities of IL-6 are potentiated when this cytokine binds soluble forms of its specific receptor subunit (sIL-6R) and the resulting complex interacts with the transmembrane signaling chain gp130. We show here that double transgenic mice expressing high levels of both human IL-6 and sIL-6R under the control of liver-specific promoters spontaneously develop nodules of hepatocellular hyperplasia around periportal spaces and present signs of sustained hepatocyte proliferation. The resulting picture is identical to that of human nodular regenerative hyperplasia, a condition frequently associated with immunological and myeloproliferative disorders. In high expressors, hyperplastic lesions progress with time into discrete liver adenomas. These data strongly suggest that the IL-6/sIL-6R complex is both a primary stimulus to hepatocyte proliferation and a pathogenic factor of hepatocellular transformation.     

Modifications of erythropoiesis in myelodysplastic syndromes treated with recombinant erythropoietin as evaluated by soluble transferrin receptor, high fluorescence reticulocytes and hypochromic erythrocytes

BACKGROUND: The aim of this study was to evaluate changes in erythropoiesis induced in vivo by recombinant erythropoietin (r-EPO) treatment in myelodysplastic syndromes (MDS), by means of some new, non invasive laboratory parameters. PATIENTS AND METHODS: Serum levels of soluble transferrin receptor (STR), a marker of total marrow erythroid activity, and automated detection of high fluorescence reticulocytes (HFR) and hypochromic erythrocytes (HE) (respectively, indexes of effective erythropoiesis and functional iron deficiency) were longitudinally measured in 25 MDS patients treated with r-EPO, and then correlated with conventional clinical and laboratory features. RESULTS: Stimulation of erythropoiesis was documented in 8 patients, whose serum STR levels showed a significant, early (within 16 days) increase during treatment with r-EPO. However, only 3 of these patients demonstrated a concomitant rise in HFR, and these were the only subjects who experienced a significant clinical response. Two of these patients also developed a functional iron deficiency while on treatment, as documented by an increase in HE, despite normal serum iron, transferrin saturation and even very high levels of ferritin. They needed iron supplementation to maintain the response to r-EPO. No variation in STR, HFR or HE occurred in the remaining 17 unresponsive patients during at least two months of treatment. Serum levels of thymidine kinase, as aspecific marker of cellular proliferative activity, paralleled those of STR. No correlation was found between STR, HFR or HE and serum levels of endogenous EPO, hemoglobin or transfusion requirements in MDS patients. CONCLUSIONS: These findings suggest that there is a heterogeneous and complex pattern of erythroid response in MDS patients treated with r-EPO. In addition, our results indicate that STR, HFR and HE may provide useful information for the clinical management of these patients.     

Low-cost accurate characterization of FM sine wave generators

A computer based test system for FM signal generators is presented. The proposed measurement procedure is based on the economical software implementation of an analog-to-digital conversion (ADC) linearization algorithm followed by an accurate short-time Fourier transform analysis with spectral interpolation. The very good accuracy performance of the system is illustrated through computer simulation and experimental results     

Rapid growth of an intracranial aneurysm causing apparent retrobulbar optic neuritis

We describe a 31-year-old man who developed sudden painful loss of vision in the right eye and was found to have a retrobulbar optic neuropathy. Magnetic resonance (MR) imaging gave normal results, and a diagnosis of retrobulbar optic neuritis was made. The patient was treated with oral prednisone, but he continued to lose vision in the right eye and then began to lose vision in the left eye. Repeat MR imaging performed eight weeks after the initial study showed a giant intracranial aneurysm compressing the right and left optic nerves. Cerebral angiography revealed that the aneurysm arose from the origin of the right ophthalmic artery. Treatment of the aneurysm by a trapping procedure resulted in improvement in vision in the left eye but no change in vision in the right eye. This report emphasizes the difficulty in imaging intracranial aneurysms of various sizes, the rapidity with which intracranial aneurysms can enlarge, and the importance of continued follow-up examinations in patients thought to have idiopathic optic neuritis.     

Control of the thymic microenvironment by growth hormone/insulin-like growth factor-I-mediated circuits

The thymus gland is a central lymphoid organ in which bone marrow-derived T cell precursors undergo maturation, eventually leading to the migration of positively selected thymocytes to the T-dependent areas of peripheral lymphoid organs. This process occurs under the influence of the thymic microenvironment, by means of secretory polypeptides and cell-cell contacts. The thymic microenvironment is a tridimensional cellular network composed of epithelial cells (its major component), macrophages, dendritic cells, fibroblasts and extracellular matrix elements. The epithelial reticulum is a heterogeneous tissue, in which a particular lymphoepithelial structure has been isolated in vitro: the thymic nurse cell complex, which possibly creates particular microenvironmental conditions for thymocyte differentiation. Additionally, thymic nurse cells are useful tools to study mechanisms involved in intrathymic T cell migration, including neuroendocrine influences. Previous data showed that thymic hormonal function can be modulated by hormones and neuropeptides, including growth hormone. Interestingly, GH acts pleiotropically on the thymic epithelium increasing cell growth and expression of extracellular matrix ligands and receptors, the latter resulting in an enhancement of thymocyte adhesion to the epithelial cells and thymocyte release from thymic nurse cells. The role of GH on thymus development is further stressed by the findings obtained with GH-deficient dwarf mice. Besides the precocious decline in serum thymulin found in these animals, a progressive thymic hypoplasia occurs, with decreased numbers of CD4+CD8+thymocytes, both defects being largely restored by long-term GH treatment. The effects of GH in the thymus are apparently mediated by IGF-1. Enhancement of thymulin secretion induced by GH, as well as the stimulation of thymocyte adhesion to thymic epithelial cells can be prevented in vitro by treatment with antibodies for IGF-I or IGF-I receptor. Moreover, in both systems IGF-I alone can yield similar effects. Also, the enhanced concanavalin-A mitogenic response and IL-6 production by thymocytes observed in GH-treated mice can be detected in animals treated with IGF-I. Lastly, mouse substrains selected for high or low IGF-I circulating levels exhibited differential thymus developmental patterns correlating with IGF-I levels. A further conceptual aspect concerning the GH-IGF-I-mediated control of thymus physiology is the recent demonstration of an intrathymic production of these molecules, leading to the hypothesis that, in addition to the classical endocrine pathway, GH-IGF-I-mediated paracrine and autocrine pathways may also be implicated in the control of thymus physiology. In any case, such control is exerted pleiotropically, with modulation in the expression of several genes in different cell types of the organ. In this respect, it is exciting to imagine a role of GH-IGF-I loops in shaping the intrathymically generated T cell repertoire.     

Optimized windows for FIR filter design to perform maximally flatdecimation stages in signal conditioning

New cosine windows, the coefficients of which have been computed through a simple optimization procedure, are proposed to minimize the sidelobe ripples. This allows maximally flat low-pass finite-duration impulse-response (FIR) filter realizations in a multistage-decimation process. In digital measuring devices this strategy is performed in order to limit the amount of data to the storage capabilities of the processor, in conjunction with filtering the data set available after oversampling to remove digitally the noise power produced by quantization. The consequent increase of the number of effective bits improves the dynamic performance of digital instrumentation, especially at lower frequencies