Producing Random Bits with Delay-Line Based Ring Oscillators

One of the sources of randomness for a random bit generator (RBG) is jitter present in rectangular signals produced by ring oscillators (ROs). This paper presents a novel approach for the design of delays used in these oscillators. We suggest using delay elements made on carry4 primitives instead of series of inverters or latches considered in the literature. It enables the construction of many high frequency ring oscillators with different nominal frequencies in the same field programmable gate array (FPGA). To assess the unpredictability of bits produced by RO-based RBG, the restarts mechanism, proposed in earlier papers, was used. The output sequences pass all NIST 800-22 statistical tests for smaller number of ring oscillators than the constructions described in the literature. Due to the number of ROs with different nominal frequencies and the method of construction of carry4 primitives, it is expected that the proposed RBG is more robust to cryptographic attacks than RBGs using inverters or latches as delay element

A Random Number Generator Using Ring Oscillators and SHA-256 as Post-Processing

Today, cryptographic security depends primarily on having strong keys and keeping them secret. The keys should be produced by a reliable and robust to external manipulations generators of random numbers. To hamper different attacks, the generators should be implemented in the same chip as a cryptographic system using random numbers. It forces a designer to create a random number generator purely digitally. Unfortunately, the obtained sequences are biased and do not pass many statistical tests. Therefore an output of the random number generator has to be subjected to a transformation called post-processing. In this paper the hash function SHA-256 as post-processing of bits produced by a combined random bit generator using jitter observed in ring oscillators (ROs) is proposed. All components – the random number generator and the SHA-256, are implemented in a single Field Programmable Gate Array (FPGA). We expect that the proposed solution, implemented in the same FPGA together with a cryptographic system, is more attack-resistant owing to many sources of randomness with significantly different nominal frequencies

Multimodal imaging of brain reorganization in hearing late learners of sign language

The neural plasticity underlying language learning is a process rather than a single event. However, the dynamics of training - induced brain reorganization have rarely been examined, especially using a multimodal magnetic resonance imaging approach, which allows us to study the relationship between functional and structural changes. We focus on sign language acquisition in hearing adults who underwent an 8‐month long course and five neuroimaging sessions. We assessed what neural changes occurred as participants learned a new language in a different modality - as reflected by task‐based activity, connectivity changes, and co‐occurring structural alterations. Major changes in the activity pattern appeared after just 3 months of learning, as indicated by increases in activation within the modality‐independent perisylvian language network, together with increased activation in modality‐dependent parieto‐occipital, visuospatial and motion‐sensitive regions. Despite further learning, no alterations in activation were detected during the following months. However, enhanced coupling between left‐lateralized occipital and inferior frontal regions was observed as the proficiency increased. Furthermore, an increase in gray matter volume was detected in the left inferior frontal gyrus which peaked at the end of learning. Overall, these results showed complexity and temporal distinctiveness of various aspects of brain reorganization associated with learning of new language in different sensory modality

Functional reorganization of the reading network in the course of foreign language acquisition

During foreign language acquisition neural representations of native language and foreign language assimilate. In the reading network, this assimilation leads to a shift from effortful processing to automated reading. Longitudinal studies can track this transition and reveal dynamics that might not become apparent in behavior. Here, we report results from a longitudinal functional magnetic resonance imaging (fMRI) study, which tracked functional changes in the reading network of beginning learners of Greek over one year. We deliberately chose Greek as foreign language that would have similar orthographic transparency but a different alphabet than the native language (Polish). fMRI scans with lexical and semantic decision tasks were performed at five different time points (every similar to 3 months). Classical language areas (the left inferior frontal gyrus, the left precentral gyrus, and the bilateral supplementary motor cortex), and cognitive control areas (left inferior parietal lobe and bilateral anterior cingulate cortex) showed stronger activation after the first months of instruction as compared to the activation before instruction. This pattern occured in both tasks. Task-related activity in the reading network remained constant throughout the remaining 6 months of learning and was also present in a follow-up scan 3 months after the end of the course. A similar pattern was demonstrated by the analysis of convergence between foreign and native languages occurring within the first months of learning. Additionally, in the lexical task, the extent of spatial overlap, between foreign and native language in Broca's area increased constantly from the beginning till the end of training. Our findings support the notion that reorganization of language networks is achieved after a relatively short time of foreign language instruction. We also demonstrate that cognitive control areas are recruited in foreign language reading at low proficiency levels. No apparent changes in the foreign or native reading network occur after the initial 3 months of learning. This suggests that task demand might be more important than proficiency in regulating the resources needed for efficient foreign language reading

Functional hierarchy for tactile processing in the visual cortex of sighted adults

Perception via different sensory modalities was traditionally believed to be supported by largely separate brain systems. However, a growing number of studies demonstrate that the visual cortices of typical, sighted adults are involved in tactile and auditory perceptual processing. Here, we investigated the spatiotemporal dynamics of the visual cortex’s involvement in a complex tactile task: Braille letter recognition. Sighted subjects underwent Braille training and then participated in a transcranial magnetic stimulation (TMS) study in which they tactually identified single Braille letters. During this task, TMS was applied to their left early visual cortex, visual word form area (VWFA), and left early somatosensory cortex at five time windows from 20 to 520 ms following the Braille letter presentation’s onset. The subjects’ response accuracy decreased when TMS was applied to the early visual cortex at the 120–220 ms time window and when TMS was applied to the VWFA at the 320–420 ms time window. Stimulation of the early somatosensory cortex did not have a time-specific effect on the accuracy of the subjects’ Braille letter recognition, but rather caused a general slowdown during this task. Our results indicate that the involvement of sighted people’s visual cortices in tactile perception respects the canonical visual hierarchy—the early tactile processing stages involve the early visual cortex, whereas more advanced tactile computations involve high-level visual areas. Our findings are compatible with the metamodal account of brain organization and suggest that the whole visual cortex may potentially support spatial perception in a task-specific, sensory-independent manner

Early results of treatment for congenital clubfoot using the Ponseti method

The purpose of this study was to evaluate the early results of the Ponseti method in reducing extensive corrective surgery rates for congenital idiopathic clubfoot in patients treated in Children’s Orthopaedic Clinic and Rehabilitation Department Medical University of Lublin between the years 2007–2011. Thirty-five patients with 47 idiopathic clubfeet were followed prospectively while being managed with the Ponseti method. Clubfoot severity was graded with use of the Dimeglio system. The initial correction was achieved, and early results were measured by using Pirani scoring method

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Non-Real-Time Wireless System for Lightning Effect Measurements

This article presents the results of experimental tests of a measuring system dedicated to the study of lightning phenomena. A wireless non-real-time communication arrangement was used as a prototype to protect the system by overvoltage and electromagnetic noise generated by high-current pulses. All data were collected after analog-to-digital conversion in the RAM of the measuring probe and then transmitted to the recorder after the surge current disappeared. The current generator creates electromagnetic disturbances resulting from its work and those arising from the impulse generated at the output. The wireless measuring system ensures safe operation and avoids measurement disturbances by resigning from the physical connection of the probe and the recorder. The proposed solution enables simultaneous (synchronous) measurement at many points, regardless of the location (for convenient change of the measurement site without cables or optical fibers). Long battery life allows measurements in the laboratory or on the test site without a power source. High accuracy of the measured signal value was obtained thanks to the 16 bit resolution, and the device parameters can be remotely modified. The wireless connection guarantees the safety of people and equipment throughout the laboratory

Computationally Efficient Wideband Spectrum Sensing through Cumulative Distribution Function and Machine Learning

Blind spectrum sensing (BSS) is crucial for identifying unknown signals in scenarios with limited prior knowledge. Traditional methods face challenges with unknown and timevarying signals, especially in the presence of noise interference. This paper addresses these issues by introducing a statistical signal processing framework that extends the use of machine learning (ML) features. Our approach improves BSS by incorporating cumulative distribution functions (CDFs) into unsupervised ML, enabling effective clustering of diverse transmission states without assumptions about specific noise distributions. Additionally, we introduce a temporal decomposition technique using shorter Fast Fourier Transforms (FFTs), enhancing the learning process, reducing system inertia, and minimizing data requirements for retraining under dynamic conditions. We evaluate our method, focusing on various features/approaches for incorporating CDFs into ML, including centroid, linear approximation, and low-order statistics. Simulation results demonstrate robust detection in a standard transmission scenario with a Gaussian pulse amidst additive white Gaussian noise, maintaining a consistently low false alarm rate. These findings highlight our BSS approach’s effectiveness and practical potential in handling unknown signals in challenging environments. This research provides valuable insights, laying the groundwork for practical implementation in real-world scenarios