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Impulse magnetron discharges with millisecond-scale pulses—extended duration modes of technological high-power impulse magnetron sputtering (HiPIMS)—have promising applications in pulsed plasma facilities of different kinds due to high ionization degree (up to 90%), suitable duration, and scalable hardware design. Depending on operating conditions, at the same power level, two distinct diffuse regimes can be distinguished: the one with intense target sputtering— long HiPIMS (L-HiPIMS),—and the non-sputtering low-voltage one (non-sputtering magnetron discharge). The majority of existing studies of these discharge forms were made for argon working gas. For a number of prospective high-power pulsed plasma applications (e. g. pulsed plasma accelerators and thrusters), however, the option of using light gases is preferable. Here, the operation of a millisecond-scale impulse magnetron discharge (L-HiPIMS) in helium has been examined. The plasma parameters (electron density, electron temperature) were measured in a time-resolved fashion with a Langmuir probe. The electrical measurements were accompanied with optical emission spectroscopy. The use of the long pulsed modes enables achieving high plasma density and accelerating the ion flux with a peak energy of ~ 10 eV.

We compared two modes of magnetron sputter deposition of MoS2 on substrates made of steel AISI 316L and bronze CuAl9NiFe4Mn1 with different initial roughness Ra 0.05–2.32 µm. The deposition was carried out at a bias voltage of −20 and +100 V, and the deposition rate of these modes differed by 30%. Measurements of the friction coefficient and lifetime tests were made in accordance with ASTM G133. Measurements of the friction coefficient and lifetime tests in vacuum at load 7H, temperature of samples 250 °C, and pressure in the chamber

Background Augmentative and alternative communication (AAC) can assist persons with complex communication needs to communicate competently with a variety of communication partners in a variety of contexts. However, AAC systems and intervention often do not take multilingual aspects into consideration. Objective This small-scale exploratory study had three aims, namely: (1) to describe the self-reported language skills of multilingual South African adults using AAC, (2) to describe the languages and communication modalities they used in interaction and (3) to obtain their views regarding access to various languages. Methods Twenty-seven adults using AAC were recruited via an empowerment programme, as well as an email list for persons interested in AAC, and provided responses to a questionnaire. To compensate for access and written language challenges, the questionnaire was administered with help and/or as a face-to-face interview where needed. Responses were analysed using mostly descriptive statistics. Results Participants generally could not express themselves in all the languages they understood and were regularly exposed to. Speech-generating devices specifically gave access almost exclusively to English. Participants expressed a desire to increase their expressive language repertoire, and mentioned both limitations of communication technology as well as their own literacy skills as barriers to overcome in this regard. Conclusion In order for multilingual South African adults using AAC to express themselves in multiple languages, appropriate AAC systems and interventions as well as literacy learning opportunities need to be developed and provided. Keywords adult, augmentative and alternative communication; multilingualism; complex communication needs, language and communication skills; self-report, views.

This work explores the effect of input text representation on the performance of a Long Short-Term Memory Recurrent Neural Network Language Model (LSTM RNNLM). Due to a problem with vanishing gradients during LSTM RNNLM training, they cannot capture long-range context information. Long-range context information often encapsulates details about the text application domain. Word embedding vectors capture similarity and semantic context information in their structure. Additional context can be captured by socio-situational setting information, topics, named entities and parts-of-speech tags. This work uses a character LSTM RNNLM as a control in experiments to determine the effect different types of input text representation have on the perplexity of an LSTM RNNLM in terms of a percentage increase or decrease in the value. Adding socio- situational information to a character LSTM RNNLM results in a 0.1 % reduction in perplexity in comparison to that of the control model. When the character embeddings are swapped with word2vec embeddings a reduction in perplexity of 2.77 % is obtained. Adding context information such as socio-situational information to the word embedded model should also result in a perplexity reduction. However, this is not the case, as the addition of socio-situational information to a word embedded model results in a 5.79 % perplexity increase in comparison to the word2vec only model. This trend of an increase in perplexity is observed in further experiments where other types of context information are added to a word embedded model. The largest increase in perplexity is obtained when word embeddings and topics are applied giving a perplexity increase of 7.55 %. This increase in perplexity is due to the addition of more data (context information) to the input text. More data means more words (unique or otherwise) that are being concatenated together as a representation of the input. This results in a larger and sparser input that not only takes longer to train but has less useful information captured on average resulting in models with a higher perplexity. A better method of text representation that will reduce the size of the input while still capturing the necessary semantic information implicit in word embeddings will be adding the vectors together instead of concatenating them.

We report on two sets of perceptual evaluations of our South African text-to-speech voices by language practitioners. In the first evaluation, we measure baseline quality in terms of how understandable and human-like the voices sound. We also determine baseline usability by asking a series of questions related to accessibility and mainstream application settings. In the second evaluation, we employ the same criteria to compare pronunciation improvements against the baseline. The results indicate success in many areas, but also illuminate room for improvement in others, especially in the cases of the African languages.

Text normalisation in text-to-speech synthesis comprises the segmentation and classification of the incoming text and the subsequent expansion of non-standard words into their standard word, spoken forms. We present a rule-based implementation for the 11 official South African languages that uses native number expansion. We discuss the architecture and performance of the implementation based on examples of cardinal and ordinal numbers, money, dates and times. Although the implementation scores well, it is currently limited to handling non-standard words in isolation. Future work will need to address sentence context in order to normalise the African languages correctly.

Persons with certain disabilities face barriers to information access and interpersonal communication. Assistive technologies provide workaround solutions to these problems. Augmentative and alternative communication systems aid the person with little or no functional speech to speak out loud. Screen readers and accessible e-books allow a print-disabled (visually-impaired, partially-sighted or dyslexic) individual to read text material by listening to audio versions. Text-to-speech synthesis converts electronic text into artificial speech and is used as the vocalisation component in the assistive technologies. For these three use cases, we report on an initial round of system integration and user engagement of the Qfrency text-to-speech voices that provide access to synthetic speech in the South African languages.

In South Africa, many persons in need of augmentative and alternative communication (AAC) come from multilingual backgrounds. There is as yet a limited evidence base (locally and internationally) for the provision of AAC services to multilingual populations. The perspectives of service providers can assist in gaining an understanding of current practices and the factors that influence these.The study aimed to obtain the perspectives of AAC service providers about practices in providing AAC systems and AAC intervention to clients from multilingual backgrounds.Fifteen AAC service providers were purposefully chosen to participate in one of three focus groups - two face-to-face and one online focus group. Data from the face-to-face focus groups was transcribed verbatim. Thematic analysis was used to identify themes and subthemes in the data.Four overarching themes were identified, namely (a) current practices, (b) factors influencing current practices, (c) service provides' orientation towards different language options in AAC intervention, and (d) needs and desired developments regarding AAC technology. This paper reports on the first three themes. Service providers reported their practices to range from a focus on L1 exclusively, L2 exclusively, to a multilingual (sequential or simultaneous) approach. The South African language context, family language preferences and choices, service provider skill and knowledge, as well as AAC technology were identified as factors influencing their practices. Although many viewed access to multiple languages through AAC as positive, they also expressed concerns and reservations about providing multilingual AAC services.Although service providers in general saw the need to give clients from multilingual backgrounds access to multiple languages using AAC, this did not always translate into multilingual AAC practices. Both extrinsic factors (e.g. the lack of appropriate AAC devices, software and apps giving access to non-English languages) and intrinsic factors (service providers' language competency and their beliefs about the cognitive demands of multilingual AAC systems) influenced their practices and choices. Appropriate AAC service delivery to multilingual populations in South Africa would require not only appropriate AAC technology developments, but also research evidence to establish the efficacy of multilingual AAC interventions for clients with a variety of characteristics.

This paper introduces a model of affect to improve prosody in text-to-speech synthesis. It operates on the discourse level of text to predict the underlying linguistic factors that contribute towards emotional appraisal, rather than any particular surface emotion itself. The architecture of the model is described and its performance is evaluated on three levels—its predictive accuracy on text, its effect on natural speech and its effect on synthesised speech. Human Language Technology Research Group, CSIR Meraka Institute, Pretoria, South Africa Multilingual Speech Technologies Group, North-West University, Vanderbijlpark, South Africa

One of the goals of text-to-speech (TTS) systems is to produce natural-sounding synthesized speech. Towards this end various natural language processing (NLP) tasks are performed to model the prosodic aspects of the TTS voice. One of the fundamental NLP tasks being used is the part-of-speech (POS) tagging of the words in the text. This paper investigates the effects of POS information on the naturalness of a hidden Markov model (HMM) based TTS voice when additional resources are not available to aid in the modeling of prosody. It is found that, when a minimal feature set is used for the HMM context labels, the addition of POS tags does improve the naturalness of the voice. However, the same effect can be accomplished by including segmental counting and positional information instead of the POS tags. Human Language Technology Competency Area, CSIR, Meraka Institute, Pretoria, South Africa Multilingual Speech Technologies, North-West University, Vanderbijlpark, South Africa Centre for Text Technology, North-West University, Potchefstroom, South Africa

Dicer is a key enzyme that processes microRNA precursors into their mature form, enabling them to regulate gene expression. Dicer null mutants die before gastrulation. To study Dicer function in testis development, we crossed mice carrying a conditional Dicer allele with an AMH-Cre transgenic line, thereby inactivating Dicer in Sertoli cells around embryonic day 14.0 (E14.0). Dicer null Sertoli cells show normal embryonic development, and at postnatal day 0 (P0), testis tubules are normal in number and histologically undistinguishable from controls. Subsequently, Dicer-mutant testes show a progressively aberrant development, so that at P6, they contain a reduced number of disorganized testis tubules leading to primary sterility. Apoptosis and prophase I assays reveal a massive wave of apoptosis starting at P3, causing progressive loss of Sertoli cells, but also of germ cells, resulting in drastically reduced testis size. Expression of genes that play crucial roles in testis development, structural integrity and spermatogenesis is downregulated at P0, before morphological changes become apparent, indicating that Dicer-mutant testes are already transcriptionally compromised at this stage. Taken together, the results of this study show that Dicer is required for Sertoli cell function and survival and for spermatogenesis in mice.

Upon binding of a decamer bis-PNA (H-Lys-TTCCTCTCTT-(eg1)3-TTCTCTCCTT-LysNH2) to a complementary target in a double-stranded DNA fragment, three distinct complexes were detected by gel mobility shift analysis. Using in situ chemical probing techniques (KMnO4 and DMS) it was found that all three complexes represent bona fide sequence-specific PNA binding to the designated target, but the complexes were structurally different. One complex that preferentially formed at higher PNA concentrations contains two bis-PNA molecules per DNA target, whereas the other two complexes are genuine triplex invasion clamped structures. However, these two latter complexes differ by the path relative to the DNA target of the flexible ethylene-glycol linker connecting the two PNA oligomers that comprise a bis-PNA. We distinguish between one in which the linker wraps around the non-target DNA strand, thus making this strand part of the triplex invasion complex and another complex that encompass the target strand only. The implications of these results are discussed in terms of DNA targeting by synthetic ligands.

Sequence-selective recognition of double-stranded (ds) DNA by homopyrimidine peptide nucleic acid (PNA) oligomers can occur by major groove triplex binding or by helix invasion via triplex P-loop formation. We have compared the binding of a decamer, a dodecamer and a pentadecamer thymine–cytosine homopyrimidine PNA oligomer to a sequence complementary homopurine target in duplex DNA using gel-shift and chemical probing analyses. We find that all three PNAs form stable triplex invasion complexes, and also conventional triplexes with the dsDNA target. Triplexes form with much faster kinetics than invasion complexes and prevail at lower PNA concentrations and at shorter incubation times. Furthermore, increasing the ionic strength strongly favour triplex formation over invasion as the latter is severely inhibited by cations. Whereas a single triplex invasion complex is formed with the decameric PNA, two structurally different target-specific invasion complexes were characterized for the dodecameric PNA and more than five for the pentadecameric PNA. Finally, it is shown that isolated triplex complexes can be converted to specific invasion complexes without dissociation of the Hoogsteen base-paired triplex PNA. These result demonstrate a clear example of a ‘triplex first’ mechanism for PNA helix invasion.

Der Kreis moge eine Stromquelle und mehrere Gerate enthalten. Hierfur sind die erforderlichen Schalter und die moglichen Schaltungen zu bestimmen.

Als erste Erweiterung des einfachen Schaltstromkreises betrachten wir ein Gebilde, welches aus einer Stromquelle und einem Gerat, aber mehreren Schaltern besteht und in der Starkstromtechnik viel verwendet wird, z. B. um die Schaltung von verschiedenen Stellen zu bewirken oder das gleiche Gerat durch mehrere Relais beim Eintritt verschiedener Betriebsbedingungen (Uberstrom, Ruckstrom, Spannungsruckgang, Frequenzabweichung usw.) zu steuern.

Der Gegenstand dieses Kapitels bewegt sich auf der Grenze zwischen Schaltung und konstruktiven Einzelheiten. Immerhin wird es fur denjenigen, der Schaltungen entwirft, von Wichtigkeit sein, einen Uberblick uber die Hilfsmittel zu erhalten, welche er als Einzelelemente seiner Schaltung fur die selbsttatige Erfullung irgendwelcher Bedingungen verwenden kann.

Eksemplaris kohaviidaga XIIIb 1930:5103 (konvoluut) kokku köidetud 18 raamatut, http://tartu.ester.ee/record=b1225645~S1*est

Die Fernschalter dienen nicht nur zur Betatigung eines Schalters aus groserer Entfernung, sondern auch zu selbsttatiger Schaltung von Stromkreisen mittels Relais, die beim Eintritt irgendwelcher unzulassiger Betriebsbedingungen in gleicher Weise wie der KommandoSchalter eines Fernsteuerungskreises den Fernschalter auslosen.

Messchaltungen sind hier nur insoweit zu erortern, als sie in Starkstromschaltanlagen fest eingebaut Verwendung finden, wahrend die Kontrollschaltungen, die nicht betriebsmasig vorzunehmen sind, ausscheiden. Von Relaisschaltungen werden nur diejenigen der Starkstromtechnik zu betrachten sein.

TÜR-i eksemplaris kohaviidaga XIIIb 1930:5103 (konvoluut) kokku köidetud 18 raamatut, http://tartu.ester.ee/record=b1225641~S1*est

Funkenentziehungen sind Vorrichtungen, die den Offnungsfunken von einem Schalter oder von den Dauerkontakten desselben ganz wegnehmen und an eine andere Stelle bringen.

Obwohl es sich hier im wesentlichen um innere Schaltungen der Maschinen handelt, sollen doch einige wichtigere Pufferschaltungen, wie sie von der Akkumulatorenfabrik-Aktiengesellschaft fur Bahnen und ahnliche stosweise arbeitende Anlagen verwendet werden, kurz beschrieben sein. Das Wesentliche ist, das bei Gleichstromanlagen an dem Sammelschienensystem sowohl das Maschinenaggregat wie die Batterie und die Verbrauchskreise liegen, und das die Batterie nicht auf konstante Spannung durch einen Zellenschalter reguliert wird, sondern das sie die Leistungsspitzen uber einer gewissen mittleren Energie abgeben und, falls der Verbrauch geringer wird, aus dem Maschinenaggregat Leistung in Form von Ladung aufnehmen soll. Da nun die Batterie eine gewisse Unempfindlichkeit hat, also nicht bei ganz geringen Anderungen der Spannung schon von Ladung auf Entladung und umgekehrt ubergeht, so kann man die Schaltung so wahlen, das die Maschine entsprechende Schwankungen hervorruft, d. h. das sie beierheblicher Energieentnahme die Spannung senkt, um die Batterie zur Entladung heranzuziehen, bei geringerem Bedarf aber die Spannung steigert, so das die Batterie geladen wird.

Als gemischte Gerate sind nach fruherer Definition diejenigen zu bezeichnen, welche zwar Strom aufnehmen und verbrauchen, aber in der Lage sind, eine elektromotorische Kraft zur Verfugung zu stellen, welche also gegebenenfalls auch als Stromerzeuger wirken konnen. Es kommen in Frage: bei konstanter Spannung: Motoren, Batterien im Ladungszustand und Transformatoren mit Stromquelle im Sekundarnetz bzw. mit sekundarer Parallelschaltung zu anderen Transformatoren; fur konstanten Strom: Motoren nach dem Reihenschaltungssystem Thury.

Der einfache Schaltstromkreis, der nur Stromquelle, Schalter und Gerat enthalt, ist ein symmetrisches Gebilde, in dem der Schalter eine eigene Rolle spielt, wahrend die beiden anderen Teile unter sich gleichwertig und austauschbar sind. Eine Dynamo, welche eine Batterie ladet, und die gleiche Batterie in Entladung auf die gleiche Dynamo, welche als Motor lauft, bilden dieselbe Schaltung. Einmal ist die Dynamo Stromquelle und die Batterie Gerat, das andere Mal umgekehrt. Man wird aber den Schalter nicht gegen die Stromquelle oder das Gerat austauschen konnen, da er anders geartet ist.

Im folgenden sollen die veralteten Schaltungen ausgeschieden werden, bei welchen wahrend der Ladung die Speisung des Netzes unmoglich ist, also insbesondere die Schaltung mit einer Maschine erhohbarer Spannung und Einfachzellenschalter. Es wird als selbstverstandliche Bedingung vorausgesetzt, das das Netz jederzeit mit normaler Spannung gespeist werden kann, ohne Rucksicht darauf, ob die Batterie gerade geladen wird.

In Wechselstromanlagen ist haufig die Notwendigkeit vorhanden, bestimmte Phasenverschiebungen von Spannungen gegeneinander, von Stromen gegen Spannungen oder von Stromen gegeneinander zu erzielen. Die Aufgabe kommt allerdings hauptsachlich in der reinen Mestechnik vor, wo die dazu erforderlichen Hilfsvorrichtungen als Teile der Mesgerate zu betrachten und im allgemeinen mit ihnen zusammengebaut sind, so das sie hier ausscheiden. Immerhin sind bisweilen solche Phasenverschiebungsvorrichtungen auch in Relaisanlagen oder in Schaltanlagen erforderlich, so das wenigstens einige kurze Ausfuhrungen und Hinweise gegeben sein mogen.