Ladislav Sieger

The dynamic biometric signature — Is the biometric data in the created signature constant?

Biometric authentication methods are increasingly proving to be a sensible compromise between the demands on the user and/or the authentication tools without reducing the level of security. Dynamic biometric signature (DBS) systems record data from the handwritten signature using special tools which enable an analysis of both the static and dynamic properties associated with the typical behaviour of the signing individual. In our previous ICCST paper (Rome, 2014) we have undertaken fundamental experiments demonstrating the uniqueness of the DBS and its resistance to forgery. Limitation of this experiment was the significance homogeneity of the used test group consisting of students from the Cybernetics Department at the Technical University in Prague. Further experiments have been undertaken with the same content, but using an absolutely heterogeneous group consisting of men and women of different ages, levels of education and professions in order to show whether the uniqueness and resistance to forgery is preserved in the DBS even in this case. A no less significant aspect when assessing the properties of the DBS is the question of the immutability and duplicability of the already created biometric data. Further questions still arise as to the degree to which the characteristics of the DBS will change when the given individual is subjected to various influences. Our experiments have therefore focused on the creation of various conditions when signing and on monitoring their influence on the stability of the researched individuals DBS. In our paper we present the results of experiments that have the considerable importance in terms of DBS credibility when being used in authentication of users.

Work of Breathing into Snow in the Presence versus Absence of an Artificial Air Pocket Affects Hypoxia and Hypercapnia of a Victim Covered with Avalanche Snow: A Randomized Double Blind Crossover Study.

Presence of an air pocket and its size play an important role in survival of victims buried in the avalanche snow. Even small air pockets facilitate breathing. We hypothesize that the size of the air pocket significantly affects the airflow resistance and work of breathing. The aims of the study are (1) to investigate the effect of the presence of an air pocket on gas exchange and work of breathing in subjects breathing into the simulated avalanche snow and (2) to test whether it is possible to breathe with no air pocket. The prospective interventional double-blinded study involved 12 male volunteers, from which 10 completed the whole protocol. Each volunteer underwent two phases of the experiment in a random order: phase “AP”—breathing into the snow with a one-liter air pocket, and phase “NP”—breathing into the snow with no air pocket. Physiological parameters, fractions of oxygen and carbon dioxide in the airways and work of breathing expressed as pressure-time product were recorded continuously. The main finding of the study is that it is possible to breath in the avalanche snow even with no air pocket (0 L volume), but breathing under this condition is associated with significantly increased work of breathing. The significant differences were initially observed for end-tidal values of the respiratory gases (EtO2 and EtCO2) and peripheral oxygen saturation (SpO2) between AP and NP phases, whereas significant differences in inspiratory fractions occurred much later (for FIO2) or never (for FICO2). The limiting factor in no air pocket conditions is excessive increase in work of breathing that induces increase in metabolism accompanied by higher oxygen consumption and carbon dioxide production. The presence of even a small air pocket reduces significantly the work of breathing.

The influence of stress on biometric signature stability

This paper directly follows on from prior research into DBS, the properties of DBS, security, its resistance to forgery and its stability. Experiments under stress situations, conducted during a survival course at the University of Defence of the Czech Republic, are described herein. It was shown that a handwritten signature developed by way of long-term practice and the reinforcement of a dynamic stereotype, consisting of the physiological, anatomical and motoric properties of each and every individual, becomes automatic to such an extent that the subconscious appending of a signature protects it from outside influences to a similar degree as we proved in the past in relation to alcohol. The experiments also identified that shorter signatures (abbreviated signature, initials) show very high variability of conformity and non-conformity between individual signatures. It was proven that the quality of recognising a signature rises with the length of the information written down. It was also again confirmed that the use of a 1st signature as “practice”, not included in the results, reduced the variability of signatures among all participants.

Breathing Experiments into the Simulated Avalanche Snow: Medical and Technical Issues of the Outdoor Breathing Trials

Avalanche burials represent one of the most dangerous risks associated with winter activities in the mountains. Asphyxiation occurs as a consequence of blocked airways; or, due to a severe hypoxia and hypercapnia resulting from rebreathing previously exhaled gas. Recently, outdoor breathing experiments with healthy volunteers were conducted in order to investigate the gas exchange limitations and work of breathing effects on the probability of survival under avalanche snow. Ambient conditions during the experiments differ significantly from the recommended operating conditions of the medical devices. Therefore, special measures need to be applied during the experiments not only to assure proper functioning of the devices used for the monitoring of the breathing subjects, but also ensuring their required precision and accuracy. As the subject starts to suffer from hypoxia and hypercapnia short after beginning of the breathing trial, careful and detailed monitoring and advanced safety precautions must be adopted. Using our experience from real outdoor breathing trials, we aim to recommend both the technical and medical precautions that should be undertaken in future studies.

Stability of a dynamic biometric signature created on various devices

The paper directly follows on from the prior research on the dynamic biometric signature (DBS), its properties, security, its resistance to forgery, and its stability. In our experiments, we used all the available pads produced by Signotec, which differ from each other in terms of their design, the size of the signature field, resolution, sampling rate, and even the scanning method used — a regular pen or a special pen using the ERT (Electromagnetic Resonance Technology). A less heterogenous sample was used than in the previous cases, as the objective of the experiments was to demonstrate a potential change in the DBS connected with the use of a different device, nevertheless the size of the sample means it is sufficiently statistically representative. The results showed that irrespective of the device used, the stability of scanning of the dynamic biometric signature was high for each person. The signature variability did not significantly differ between the devices for individual people. Once again it was confirmed that the use of the first signature as a “trial”, not included in the results, reduces the signature variability for each participant.

Data processing from lobster eye type optics

Wolter I optics are commonly used for imaging in X-Ray spectrum. This system uses two reflections, and at higher energies, this system is not so much efficient but has a very good optical resolution. Here is another type of optics Lobster Eye, which is using also two reflections for focusing rays in Schmidts or Angels arrangement. Here is also possible to use Lobster eye optics as two one dimensional independent optics. This paper describes advantages of one dimensional and two dimensional Lobster Eye optics in Schmidts arrangement and its data processing - find out a number of sources in wide field of view. Two dimensional (2D) optics are suitable to detect the number of point X-ray sources and their magnitude, but it is necessary to expose for a long time because a 2D system has much lower transitivity, due to double reflection, compared to one dimensional (1D) optics. Not only for this reason, two 1D optics are better to use for lower magnitudes of sources. In this case, additional image processing is necessary to achieve a 2D image. This article describes of approach an image reconstruction and advantages of two 1D optics without significant losses of transitivity.

Optimization of microroughness of replicated x-ray optics

We report on our work of minimizing the microroughness of replicated grazing incidence X-ray optics. Ion beam and RF sputter cleaning was used as surface treatment and we compare its effects in the article. Vacuum deposition of smoothing layers was also used for minimizing the microroughness. The surfaces were measured by atomic force microscopy and X-ray reflectometry. Microroughness less than 0,5 nm RMS and Ra was achieved.

Uncooled spectrometer for x-ray astrophysics

In the field of X-ray detection for Astrophysics there are mainly two objectives; first is to create 2D images as a result of sensing radiation by detectors consisting of a pixels matrix and the second is a spectral analysis of the incident radiation. For spectral analysis, the basis is usually the principle of diffraction. This paper describes the new design of X-ray spectrometer based on Timepix detector with optics positioned in front of it. The advantage of this setup is the ability to get the image and spectrum from the same devices. With other modifications is possible to shift detection threshold into areas of soft X-ray radiation.