Imaging shear stress distribution and evaluating the stress concentration factor of the human eye.

Healthy eyes are vital for a better quality of human life. Historically, for man-made materials, scientists and engineers use stress concentration factors to characterise the effects of structural non-homogeneities on their mechanical strength. However, such information is scarce for the human eye. Here we present the shear stress distribution profiles of a healthy human cornea surface in vivo using photo-stress analysis tomography, which is a non-intrusive and non-X-ray based method. The corneal birefringent retardation measured here is comparable to that of previous studies. Using this, we derive eye stress concentration factors and the directional alignment of major principal stress on the surface of the cornea. Similar to thermometers being used for monitoring the general health in humans, this report provides a foundation to characterise the shear stress carrying capacity of the cornea, and a potential bench mark for validating theoretical modelling of stresses in the human eye in future

Reduction of suicidal ideation in patients undergoing psychotherapy in the day hospital for the treatment of neurotic and behavioral disorders and neurotic symptoms reported by them before the hospitalization

Aim. Analysis of associations between symptoms reported before the beginning of the hospitalization and reduction of suicidal ideation – or its lack – obtained until the end of the hospitalization in patients of the day hospital for the treatment of neurotic and behavioral disorders. Material and method. Symptoms Checklist KO“O” and Life Inventory completed by 461 women and 219 men treated with intensive integrative psychotherapy with predominance of psychodynamic approach in the day hospital due to neurotic, behavioral and personality disorders between 2005-2013. Percentages of patients reporting SI initially and at the end of the treatment were 29.1% and 10.2% respectively in women and 36.5% and 13.7% in men. The improvement in terms of initially reported SI was obtained by 84.3% of women and 77.5% of men. Among patients, those initially reporting SI were characterized by greater intensity of neurotic symptoms (p<0.001) and greater intensity of nearly all of 14 subtypes of neurotic symptoms(p<0.05). Results. Among those reporting SI, subgroups of women with greater intensity of Obsessive-compulsive symptoms (p=0.003), Neurasthenia (p=0.005), Autonomic disorders (p=0.044) and women reporting episodes of uncontrollable hunger (p<0.01) had significantly lower chances of improvement in terms of SI than others. Conclusions. Patients initially reporting SI constituted approximately 1/3 in both genders and were characterized by greater intensity of neurotic disorders. Among those, women with particularly higher intensity of Obsessive-compulsive symptoms, Neurasthenia and Autonomic disorders and women reporting episodes of uncontrollable hunger seemed to suffer from SI that were more resistant to the psychotherapy. As such, those subgroups of women require special attention and diligent selection of the therapeutic methods

Applanation pressure function in Goldmann tonometry and its correction

So far applanation tonometry has not worked out any theoretical basis for correcting the result of intraocular pressure measurement carried out on a cornea with noncalibration dimensions by means of the Goldmann tonometer. All the tables of instrument reading corrections for cornea thickness or cornea curvature radius are based exclusively on measurements. This paper represents an attempt at creating a mechanical description of corneal apex deformation in Goldmann applanation tonometry. The functional dependence between intraocular pressure and the pressure exerted on the corneal apex by the tonometer was determined from a biomechanical model. Numerical GAT simulations, in which this function was also interrelated with the cornea’s curvature radius and thickness were run and a constitutive equation for applanation tonometry, i.e. a full analytical description of intraocular pressure as a function of the above variables, was derived on this basis. The correction factors were defined and an algorithm for correcting the measured pressure was formulated. The presented formalism puts the results of experimental tonometry in new light. Analytical correction factors need not to come exclusively from measurements. A geometric interdependence between them and their dependence on pressure have been revealed. The theoretical description of applanation tonometry contained in the constitutive equation consists of a pressure function developed for a cornea with calibration dimensions and a coefficient correcting this calibration function, dependent exclusively on the cornea’s actual thickness and curvature radius. The calibration function is a generalization of the Imbert–Fick law

The use of mosses in biomonitoring of selected areas in Poland and Spitsbergen in the years from 1975 to 2014

We have compared historical changes in concentrations of the heavy metals Mn, Ni, Cu, Zn, Cd and Pb accumulated in samples from the Polish woodlands of Beskidy and Karkonosze (S, SE Poland) and the north-east regions of the country, versus the relatively little polluted areas of Spitsbergen of the Svalbard Archipelago. We have combined the results from literature with new results from 2014. The regions of Beskidy and Karkonosze were the most exposed to heavy metals deposition. However, from 1975 to 2014 there was a considerable decrease of concentrations of Cu, Zn, Cd and Pb at all Polish sites, clearly signifying improvement of environmental quality. For example, the average Cd concentration in mosses samples collected in Karkonosze decreased from 0.002 mg/g in 1975 to 0.0006 mg/g in 2014. It is interesting to observe relatively large concentrations of nickel in moss samples collected in 2014 in the Svalbard archipelago, in the vicinity of Longyearbyen (average 0.018 mg/g) which most likely originate from local mine waste piles. air pollutions, biomonitoring, heavy metals, mosses, Poland, Svalbar