Spectral refinement with adaptive window-size selection for voicing detection and fundamental frequency estimation

Spectral refinement (SR) offers a computationally in-expensive means of generating a refined (higher resolution) signal spectrum by linearly combining the spectra of shorter, contiguous signal segments. The benefit of this method has previously been demonstrated on the problem of fundamental frequency (F0) estimation in speech processing – specifically for the improved estimation of very low F0. One drawback of SR is, however, the poorer detection of voicing onsets due to the Heisenberg-Gabor limit on time and frequency resolution. This may also lead to degraded performance in noisy conditions. Transitioning between long- and short-time windows for the spectral analysis may offer a good trade-off in these situations. This contribution presents a method to adaptively switch between short- and long-time windows (and, correspondingly, between the short-term and the refined spectrum) for voicing detection and F0 estimation. The improvements in voicing detection and F0 estimation due to this adaptive switching is conclusively demonstrated on audio signals in clean and corrupted conditions

Generalized refinement of short-term fourier spectra in time- and frequency-domain and its combination with polyphase filterbanks

In this contribution a generalized solution for the spectral refinement (SR) of signals is presented. SR essentially consists of a linear combination of weighted and shifted input signal segments (either in the time or the subband domain), yielding a refined (higher resolution) version of the underlying short-term spectrum. The proposed method is particularly suitable for speech processing systems with an existing analysis filterbank based on polyphase or DFT realizations. We first show that DFT-modulated filterbanks that incorporate SR in the time-domain can be seen as a specific realization of polyphase-based analysis filterbanks. Next, the polyphase-based analysis filterbanks will be combined through the proposed generalized form of SR, in the frequency domain. The resulting structure can be applied to refine either the frequencies of the short-term spectrum (or a subset thereof) or to refine the whole frequency range, including additional frequency supporting points. Lastly, as a potential application, we demonstrate the benefit of combining an existing polyphase filterbank with SR for the problem of pitch extraction/fundamental frequency estimation. Especially for lower fundamental frequencies, such combination can give a significant performance improvement compared to estimates based on the original signal spectrum

Changing pattern in the clinical presentation of pediatric celiac disease: A 30-year study

Background/Aims: The incidence of celiac disease (CD) has increased in recent years due to the recognition of atypical forms and the identification of silent cases through serological screening. Our aim was to detect temporal trends in the presentation of pediatric CD in Greece. Methods: We reviewed the medical files of all children diagnosed with CD between 1978 and 2007 at a single academic pediatric center. Cases were classified according to the year of diagnosis. We examined demographic data, presenting symptoms, delay to diagnosis, and the prevalence of associated conditions. Results: During the study period, 284 new cases of CD were diagnosed. The incidence of CD was significantly increased in recent years (p < 0.05). We observed significant trends towards older age at diagnosis (p < 0.001), longer delay to diagnosis (p < 0.05) and decreased frequency of the classical and/or gastrointestinal predominant mode of presentation (p < 0.001). In recent years, diagnosis of CD was significantly more frequent due to testing of asymptomatic children with a positive family history for CD or personal history of associated conditions (p < 0.001). Conclusion: We report a changing pattern in the presentation of pediatric CD in Greece. CD is diagnosed more frequently in older children, oftentimes presents with atypical symptoms, and is increasingly detected through serological screening. CD should be considered in the presence of atypical presentations. Copyright © 2009 S. Karger AG, Basel

Novel genetic risk variants for pediatric celiac disease

Background: Celiac disease is a complex chronic immune-mediated disorder of the small intestine. Today, the pathobiology of the disease is unclear, perplexing differential diagnosis, patient stratification, and decision-making in the clinic. Methods: Herein, we adopted a next-generation sequencing approach in a celiac disease trio of Greek descent to identify all genomic variants with the potential of celiac disease predisposition. Results: Analysis revealed six genomic variants of prime interest: SLC9A4 c.1919G>A, KIAA1109 c.2933T>C and c.4268-4269delCCinsTA, HoxB6 c.668C>A, HoxD12 c.418G>A, and NCK2 c.745-746delAAinsG, from which NCK2 c.745-746delAAinsG is novel. Data validation in pediatric celiac disease patients of Greek (n = 109) and Serbian (n = 73) descent and their healthy counterparts (n = 111 and n = 32, respectively) indicated that HoxD12 c.418G>A is more prevalent in celiac disease patients in the Serbian population (P < 0.01), while NCK2 c.745-746delAAinsG is less prevalent in celiac disease patients rather than healthy individuals of Greek descent (P = 0.03). SLC9A4 c.1919G>A and KIAA1109 c.2933T>C and c.4268-4269delCCinsTA were more abundant in patients; nevertheless, they failed to show statistical significance. Conclusions: The next-generation sequencing-based family genomics approach described herein may serve as a paradigm towards the identification of novel functional variants with the aim of understanding complex disease pathobiology. © 2016 The Author(s)