A batch-service queueing model with a discrete batch Markovian arrival process

Queueing systems with batch service have been investigated extensively during the past decades. However, nearly all the studied models share the common feature that an uncorrelated arrival process is considered, which is unrealistic in several real-life situations. In this paper, we study a discrete-time queueing model, with a server that only initiates service when the amount of customers in system (system content) reaches or exceeds a threshold. Correlation is taken into account by assuming a discrete batch Markovian arrival process (D-BMAP), i.e. the distribution of the number of customer arrivals per slot depends on a background state which is determined by a first-order Markov chain. We deduce the probability generating function of the system content at random slot marks and we examine the influence of correlation in the arrival process on the behavior of the system. We show that correlation merely has a small impact on the threshold that minimizes the mean system content. In addition, we demonstrate that correlation might have a significant influence on the system content and therefore has to be included in the model

Advances in Fish Research

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Small indigenous fishes and their importance in human health.

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Amplitude Modulation Structure in French and German Poetry: Universal Acoustic Physical Structures Underpin Different Poetic Rhythm Structures

French and German poetry are classically considered to utilize fundamentally different linguistic structures to create rhythmic regularity. While German poetry utilizes lexical stress to create prosodic alternation between strong and weak syllables, French poetry relies on accentuation at the level of prosodic phrasing. These differences result in metrical rhythm structures considered poetically to be very different. However, the biophysical and neurophysiological constraints regarding the speakers of these poems are highly similar, suggesting potential similarity at the level of the acoustic physical structures that are produced orally. Here we apply a language-blind computational model of linguistic rhythm based on features of the amplitude envelope to compute these physical stimulus characteristics. The model was applied to recordings of the recitation of metrical French and German poems by native speakers. Poems in free verse were not considered in the study. The results indicated that the poems’ acoustic physical structures were identical for the two languages in terms of temporal modulation patterns in the amplitude envelope. Nevertheless, minor differences in physical structure could be detected by applying further modelling drawn respectively from the birdsong and neural connectivity literatures. The data are interpreted with respect to current controversies in the poetic literature

Atypical speech production of multisyllabic items by children with developmental language disorder (DLD) indicate prosodic difficulties

Purpose: Developmental language disorder (DLD) is typically characterized by a core grammatical impairment, yet spoken word production can also exhibit atypical phonology, for example the omission of unstressed syllables. This may indicate a role for the sensory/neural processing of syllable stress patterns in the aetiology of DLD. Here we explore this connection by investigating the accuracy of the production of multisyllabic words from a speech rhythm/syllable stress perspective. Method: We adapted a computerized speech copying task originally designed for children with dyslexia, in which participants copy aloud familiar targets like “alligator”. Fifty-seven children with and without DLD were tested with a 30-item battery comprising equal numbers of 2-syllable, 3-syllable and 4-syllable words. The children with DLD (N=20) were compared with both age-matched typically-developing control children (AMC, N=21) and younger typically-developing control children with less mature language skills (younger language controls, YLC, N=16). Similarity of the child’s productions to the target in terms of the speech amplitude envelope (AE) and pitch contour was computed using two similarity metrics, correlation and mutual information. Both the speech AE and the pitch contour contain important information about stress patterns and intonational information. Results: Children with DLD were significantly less accurate than AMC at copying the multi-syllabic targets, for both the AE and the pitch contour. The opportunity to repeat the targets had no impact on performance, for any group. Word length effects were similar across groups. Conclusion: The spoken production of multisyllabic words by children with DLD is atypical regarding both the AE and the pitch contour. This is consistent with a theoretical explanation of DLD based on impaired sensory/neural processing of speech rhythm

EEG data

Raw and preprocessed EEG data used in the analysi