A Contribution to the System-Theoretic Approach to Bandwidth Estimation

The network calculus provides a theoretical background for description of traffic in computer networks. Using this tool in explanation of the so-called pathchirp method of measuring the available bandwidth, the validity and range of application of some relationships exploited are verified in this paper. The derivations are carried out in a wider context than that considered in a recent paper by Liebeherr et al. published in IEEE/ACM Transactions on Networking on network bandwidth estimation, providing thereby new insights and outcomes. These results, summarized in a table, show a means of bounding the service curve, depending upon its convexity or non-convexity property assumed and upon the linearity or non-linearity of a network considered. Moreover, it is shown here that the nonlinear network example analyzed by Liebeherr et al. can be viewed equivalently as a linear parametric network. For this network, the behaviour of the cross traffic is considered in a more detail, too

The use of eye-tracking methods for evaluation of responsive web application

The purpose of this article is to present the eye-tracking method in the context of evaluation of responsive web application dedicated to manage students practices. To determine usability of the application the eye-tracking method has been chosen due to its high objectivity. Using this method one can unequivocally determine the user gaze direction, which interface elements enchained his attention and which ones were completely skipped. As part of the work were prepared scenarios with tasks for the research participants, questionnaires and time of the tasks execution where measured. Collected data were presented as heat maps and scanpaths. The paper covers also actual review of bibliography of the eye-tracking area and detailed description of the eye-tracking method. What is more the paper gives description of test subject, conducted test and discusses results

Quantitative immunohistochemical assessment of clinically non-functioning pituitary adenomas

Introduction. Immunohistochemical staining is currently the gold standard of diagnostic and classification of pituitary adenomas. However, there are some discrepancies between immunohistochemical staining results and the clinical picture of pituitary adenomas. Pituitary adenomas with positive immunohistochemical reaction might not cause any endocrinological symptoms or changes in serum pituitary hormone levels. Such a discordance may be caused partly by clinically non-functioning pituitary adenomas (CNFPAs). The aim of our study was to establish the frequency of CNFPAs and identify their histological types using quantitative immunohistochemical assessment. Materials and methods. We enrolled in the study 72 patients with pituitary adenoma, and their medical history was evaluated retrospectively. The immunohistochemical panel of anterior pituitary hormones was introduced in all cases. The immunoreactivity index was calculated manually for each specimen. Results. 36.1% patients of the evaluated group presented as CNFPAs. Among the CNFPA patients we found 38.46% cases with positive immunohistochemical reaction for one or more anterior pituitary lobe hormones. In 23.07% of cases the adenomas were monohormonal, and in 15.38% they were plurihormonal. Conclusions. The morphometric method utilising the immunoexpression index introduced in this study provided a very precise recognition of pituitary adenoma pathology. In the case of CNFPAs the immuno-histochemical staining often reveals a positive reaction also for multiple pituitary hormones. Quantitative assessment limits the subjectivity of the examiner and allows objective results comparison, so it should become a standard in histopathological assessment of pituitary adenomas

The reliability of the specimens for neuropathological evaluation in pituitary adenomas treated via transphenoidal route

Introduction: There are some discrepancies between immunohistochemical staining results and clinical picture of pituitary adenomas. Such a discordance may be caused by multiple factors. The problem of securing the histopathological material during the transsphenoidal pituitary surgery and its reliability for neuropathological evaluation deserves a special attention. The surgical biopsy does not always meet the criteria required for a immunohistochemical staining and sometimes not even for the routine histopatho-logical examination. Aims: To determine the frequency of unreliable material for histopathological examination and factors influencing the reliability of histopathological specimens after surgery for pituitary adenomas. Material and methods: The hematoxylin and eosin sections were examined in detail. with a special attention to the presence of incidental findings, i.e. admixture of normal pituitary gland tissue, signs of hemorrhage, necrosis, thermal artifacts, inflammatory changes, respiratory epithelium, vessels or cholesterol granuloma. The impact of incidental findings on further immunohistochemical analysis was investigated. The relationship between the magnetic resonance imaging (MRI)- determined tumor size and the area of histopathological specimen was assessed and considered as a reliability parameter. Results: The unreliable material was estimated at the level of 11.8%. It was assessed that hemorrhages, neurohypophysis, necrosis and quantity of collected histopathological material had the statistically sig-nificant impact on the reliability of the histopathological material. The statistical analysis did not show any relation between the reliability of the histopathological material and the MRI-determined volume of the tumor. Conclusions: The presence of some additional tissue elements and artifacts in the histopathological specimen makes the immunohistochemical evaluation difficult or even impossible. However, this problem is related to a relatively low percentage of cases, mainly small tumors