Observation and its History

Recenze: Lorraine DASTON - Elizabeth LUNBECK, E., Histories of Scientific Observation. Chicago - London: University of Chicago Press 2011, 460 pp

On an argument of J.--F. Cardoso dealing with perturbations of joint diagonalizers

B. Afsari has recently proposed a new approach to the matrix joint diagonalization, introduced by J.--F. Cardoso in 1994, in order to investigate the independent component analysis and the blind signal processing in a wider prospective. Delicate notions of linear algebra and differential geometry are involved in the works of B. Afsari and the present paper continues such a line of research, focusing on a theoretical condition which has significant consequences in the numerical applications.Comment: 9 pages; the published version contains significant revisions (suggested by the referees

On the Connectivity of the Sylow Graph of a Finite Group

The Sylow graph $\Gamma(G)$ of a finite group $G$ originated from recent investigations on the so--called $\mathbf{N}$--closed classes of groups. The connectivity of $\Gamma(G)$ was proved only few years ago, involving the classification of finite simple groups, and the structure of $G$ may be strongly restricted, once information on $\Gamma(G)$ are given. The first result of the present paper deals with a condition on $\mathbf{N}$--closed classes of groups. The second result deals with a computational criterion, related to the connectivity of $\Gamma(G)$.Comment: 8 pp. with Appendix; Fundamental revisions have been don

Institutions and Dissent: Historical Geology in the Early Royal Society

The paper aims to ques- tion the traditional view of the early Royal Society of London, the oldest scientific institution in continuous existence. According to that view, the institutional life of the Society in the early decades of activity was characterized by a strictly Baconian methodology. But the re- construction of the discussions about fossils and natural history within the Society shows that this monolithic image is far from being correct. Despite the persistent reference to the Baconian Solomon House, the Society did not impose or support a common programme of research in the field of the natural history of the Earth

The Invalidity of the Laplace Law for Biological Vessels and of Estimating Elastic Modulus from Total Stress vs. Strain: a New Practical Method

The quantification of the stiffness of tubular biological structures is often obtained, both in vivo and in vitro, as the slope of total transmural hoop stress plotted against hoop strain. Total hoop stress is typically estimated using the "Laplace law." We show that this procedure is fundamentally flawed for two reasons: Firstly, the Laplace law predicts total stress incorrectly for biological vessels. Furthermore, because muscle and other biological tissue are closely volume-preserving, quantifications of elastic modulus require the removal of the contribution to total stress from incompressibility. We show that this hydrostatic contribution to total stress has a strong material-dependent nonlinear response to deformation that is difficult to predict or measure. To address this difficulty, we propose a new practical method to estimate a mechanically viable modulus of elasticity that can be applied both in vivo and in vitro using the same measurements as current methods, with care taken to record the reference state. To be insensitive to incompressibility, our method is based on shear stress rather than hoop stress, and provides a true measure of the elastic response without application of the Laplace law. We demonstrate the accuracy of our method using a mathematical model of tube inflation with multiple constitutive models. We also re-analyze an in vivo study from the gastro-intestinal literature that applied the standard approach and concluded that a drug-induced change in elastic modulus depended on the protocol used to distend the esophageal lumen. Our new method removes this protocol-dependent inconsistency in the previous result.Comment: 34 pages, 13 figure

The Translation Evidence Mechanism. The Compact between Researcher and Clinician.

Currently, best evidence is a concentrated effort by researchers. Researchers produce information and expect that clinicians will implement their advances in improving patient care. However, difficulties exist in maximizing cooperation and coordination between the producers, facilitators, and users (patients) of best evidence outcomes. The Translational Evidence Mechanism is introduced to overcome these difficulties by forming a compact between researcher, clinician and patient. With this compact, best evidence may become an integral part of private practice when uncertainties arise in patient health status, treatments, and therapies. The mechanism is composed of an organization, central database, and decision algorithm. Communication between the translational evidence organization, clinicians and patients is through the electronic chart. Through the chart, clinical inquiries are made, patient data from provider assessments and practice cost schedules are collected and encrypted (HIPAA standards), then inputted into the central database. Outputs are made within a timeframe suitable to private practice and patient flow. The output consists of a clinical practice guideline that responds to the clinical inquiry with decision, utility and cost data (based on the "average patient") for shared decision-making within informed consent. This shared decision-making allows for patients to "game" treatment scenarios using personal choice inputs. Accompanying the clinical practice guideline is a decision analysis that explains the optimized clinical decision. The resultant clinical decision is returned to the central database using the clinical practice guideline. The result is subsequently used to update current best evidence, indicate the need for new evidence, and analyze the changes made in best evidence implementation. When updates in knowledge occur, these are transmitted to the provider as alerts or flags through patient charts and other communication modalities