Updated Key Research Articles

(Invited) Updated Key Issues for SiC MOSFET Reliability

This work will provide an updated overview of our understanding of several key reliability issues for SiC power MOSFETs, including threshold-voltage stability, body-diode robustness, and short-circuit current robustness. We will also discuss recent results regarding the modeling of high-field breakdown in SiC and other power semiconductor devices.Threshold-voltage instability likely occurs due to the charging and discharging of near-interfacial oxide traps in response to a change in gate bias. If enough traps change charge state, it can lead to significant shifts in the threshold voltage, which may in turn lead to increases in leakage current in the off state, or increases in on-state resistance in the on state. An important question is, what is the best—or most appropriate—test method to use to determine the reliability of these devices. A key factor is the measurement speed used to determine the magnitude of the threshold-voltage instability. It has recently been observed that one commercial device manufacturer has large instabilities, even in previously unstressed devices, and that such large instabilities can result in significant increases in on-resistance during normal switching conditions, thereby degrading circuit performance.Some suppliers of SiC power MOSFETs are producing devices with low basal plane dislocation (BPD) density, resulting in decreased bipolar degradation during normal operation of its integral body-diode. However, not all suppliers manage their BPD densities to the same degree, resulting in a variation in responses observed across suppliers. Even devices from a single supplier with the same date code exhibited varying levels of degradation for identical body-diode stress and measurement conditions. Unlike other extended defects, BPDs when faulted, leads to degradation in both the body-diode and MOSFET characteristics. These faulted BPDs induce stacking faults that expand over time and limits the reliability of some commercially available SiC MOSFETs. This degradation phenomenon necessitates the development of an appropriate reliability test standard for SiC to separate good devices from bad ones. Three of the five major suppliers of 1200-V SiC MOSFETs showed varying levels of bipolar degradation in both their body-diode forward voltages and their MOSFET on-resistances. Two out of three suppliers of 1700-V SiC MOSFETs showed significant bipolar degradation issues with one particular supplier’s devices showing forward voltage changes of 1.3 V to 2.5 V from their pre-stress values. Their on-state resistance values were also significantly degraded.Another important aspect of SiC MOSFET reliability is its robustness to short-circuit current conditions that can occur in many power electronics applications utilizing a half-bridge topology. Since both planar and trench device architectures are commercially available, electrical results have been generated to highlight their short-circuit capabilities under similar circuit conditions. Our electrical results show that trench devices have lower robustness in comparison to planar devices of similar ratings. These differences in short-circuit withstand times can be attributed to the smaller heat conduction volume of the trench design coupled with its higher saturation drain current for the same gate-drive voltage. The existing test method for short-circuit withstand time in the MIL-STD may overestimate the actual withstand time because it relies on a single gate-pulse method. Electrical results indicate that an incremental gate-pulse method may be more accurate in determining the actual withstand time, and it has proven to be more effective in determining latent failures missed by the standard method.Another key issue for power devices in general is the trade-off between on-state resistance and blocking voltage. One of the key advantages of wide bandgap (WBG) materials such as SiC is that it can block the same voltage as Si using a much thinner, and more highly-doped, blocking layer. This results in a much lower on-state resistance at the same rated voltage. The superior high-field properties of WBG (and ultra WBG) power semiconductor materials also enable them to block much higher voltages than Si is able—as long as the background doping is low enough. We will present recent work, using impact ionization coefficients from the literature, to calculate avalanche breakdown as a function of epi-layer thickness and doping, thereby determining on-state resistance versus breakdown voltage for SiC and GaN. We will compare these results to Si, as well as to UWBG materials such as diamond, AlGaN, and Ga2O3. It is observed that SiC and GaN have very similar characteristics in terms of critical field, and in their relationships between on-state resistance and blocking voltage.

Forward secure certificateless proxy multi-signature scheme

In order to deal with key exposure problem, we introduce forward secure technique into certificateless proxy multi-signature scheme, and give the formal definition and security model of forward secure certificateless proxy multi-signature. Furthermore, we present a construction of forward secure certificateless proxy multi-signature scheme. Based on the difficulty of computational Diffie-Hellman problem, the proposed scheme is existentially unforgeable against adaptively chosen-message attacks and chosen-warrant attacks in the random oracle model. The proposed scheme does not use bilinear pairs in the key update and generation proxy signature phases, and updated proxy key is easy, thus it is more suitable for mobile environments. Our scheme has effectively dealt with the key exposure problem and certificate management problem.

New species and stages description of Traverella Edmunds, 1948 (Ephemeroptera: Leptophlebiidae) from Northeast Brazil.

The genus Traverella Edmunds, 1948 (Ephemeroptera: Leptophlebiidae) has 15 described species, three of them recorded from Brazil: Traverella bradleyi (Needham Murphy, 1924), T. insolita Nascimento Salles, 2013 and T. maranhensis Nascimento, Lima Azevedo, 2019. In the present work, we provide the description of a new species to the genus based on nymphs and male imagos and provide description of the nymphal stage of T. maranhensis, based on collections from Maranhão State. Additionally, an updated key of male imagos is provided.

Steganoderma Stafford, 1904 (Digenea: Zoogonidae: Lepidophyllinae) from Two Species of Rockfishes from Deep Waters off Oregon Including a New Species and an Updated Key to Species of This Genus

Steganoderma eamiqtrema n. sp. and a single unidentified specimen of Steganoderma Stafford, 1904 (Zoogonidae: Lepidophyllinae) obtained from the intestine of the greenstriped rockfish, Sebastes elongatus Ayres, 1859, and the flag rockfish, Sebastes rubrivinctus (Jordan and Gilbert, 1880) (Scorpaeniformes: Sebastidae), collected from 190–200 m depths off Oregon, USA, are described. The new species is distinguished from its seven other congeners by a diagnostic combination of morphological features including an elongate oval to spindle-shaped body, a clavate to comma-shaped cirrus pouch located in the forebody and hindbody, a bipartite seminal vesicle, a bifurcal or just post-bifurcal genital pore, a larger ventral than oral sucker, and a smooth testes and ovary with a relatively small distance between them. We present an updated key to the eight species now in Steganoderma and provide a list of parasites known from Se. elongatus and Se. rubrivinctus. The discovery of S. eamiqtrema in Se. elongatus represents the second species of zoogonid known from this host, and the finding of Steganoderma sp. in Se. rubrivinctus represents the first report of a digenean from this host species. A detailed discussion also is given of the type species, S. formosum Stafford, 1904, and questions are raised as to whether this species has a worldwide distribution and infects such a wide variety of fish hosts. We present evidence including variation we observed in redescriptions of the type species, query the implausible idea that there could be gene flow between conspecific helminths geographically separated in the North Atlantic and North Pacific Oceans over such a vast geological period, and offer the possibility that some prior reports of S. formosum may, indeed, be S. eamiqtrema; all of which suggests S. formosum sensu lato may be part of a species complex and not the same worldwide species. Steganoderma is represented in the deep sea by S. eamiqtrema, S. formosum, and Steganoderma sp., and limited speculation is given as to the host specificity of this genus and life history strategies of the new species in deeper waters. Finally, molecular studies of species of Steganoderma are sorely needed (i.e., there is no DNA sequence data currently available in GenBank for any species of this genus), and we suspect that with further molecular, morphological, and life history work, this genus will be taxonomically divided up.

A predicted new Geotrupes from the mountains of Oaxaca, Mexico, and a description of the male of Geotrupes lobatus (Coleoptera: Geotrupidae)

Geotrupes nuntiatus Kohlmann & Arriaga-Jiménez, sp. nov., is described from the Mixteca shield, in the mountains of Oaxaca, Mexico. Its habitat, distribution, and ecology are discussed. The male of Geotrupes lobatus Howden, 1974 is described for the first time. An updated key of the genus for the state of Oaxaca is presented to facilitate identification. Photographs of the specimens, diagnostic features, and their aedeagi, as well as distribution maps, are also included.

<p><strong>Taxonomic revaluation of the <em>Polylepis pauta</em> and<em> P. sericea</em> (Rosaceae) from Ecuador</strong></p>

We conducted a taxonomic revaluation of the Polylepis pauta and P. sericea complexes in Ecuador, recognizing five species, three of which are described as new: Polylepis humboldtii sp. nov., P. loxensis sp. nov., P. longipilosa sp. nov., P. ochreata, and P. pauta. We provide descriptions of all species, full specimen citations, and updated keys to genus Polylepis in Ecuador and to the P. pauta and P. sericea complexes in general.

Taxonomic revision of the Boiga ceylonensis group (Serpentes: Colubridae): re-examination of type specimens, redefinition of nominate taxa and an updated key.

We conducted a taxonomic revision of the arboreal snakes of the Boiga ceylonensis-group, all inhabiting the Indian subcontinent. Based on 15 characters, recorded from more than 100 specimens, representing eight recognized taxa, we conducted a multivariate morphometric analysis to redefine the taxonomic boundaries. We provide redescriptions of the nominate taxa in this group based on re-examination of the name-bearing types. The types of B. ceylonensis, B. beddomei, B. barnesii, B. dightoni, B. nuchalis and B. andamanensis are redescribed, where appropriate lectotypes are selected, illustrated and their nomenclature, synonymy and distribution are discussed. Status of the nominate taxon Boiga ceylonensis dakhunensis Deraniyagala, 1955 is fixed as an objective junior synonym of Dipsas nuchalis Günther, 1875. An updated key to the species of this group is presented.

Cranichis crenatifolia (Orchidaceae), a New Species from Valle de Sibundoy, Colombia

Cranichis crenatifolia Kolan. & Szlach. sp. nova (Orchidaceae) from the Colombian department of Putumayo is described and illustrated. It can be easily distinguished from all other members of the Pleioneura group in Cranichis by crenate and undulate leaf margins and hairy petals. It also differs from the somewhat similar C. atrata by having an obovate vs. an elliptic-ovate lip. An updated identification key is provided to the Colombian species in the Pleioneura group of Cranichis.

<p class="Body"><strong>A new species of the genus <em>Caeculus</em> Dufour (Acari: Caeculidae) from Mexico, with an updated key for the genus</strong></p>

Caeculus veracruzensis sp. nov. is described based on exemplars collected in soil samples from La Mancha, Veracruz, México. An updated key is presented for the species of the genus Caeculus based on putatively more stable characters.

A new species of rake-legged mite, Caeculus cassiopeiae (Prostigmata, Caeculidae), from Canada and a systematic analysis of its genus.

The genus Caeculus Dufour (Prostigmata, Caeculidae) contains 19 previously described species, most of which are found in North America, and for which no comprehensive phylogenetic treatment exists. Here, one new species from Alberta, Canada, is described: Caeculus cassiopeiae Bernard & Lumley, sp. nov., and another caeculid known to be present in Canada is documented. The new species is characterized within the genus with a character state matrix, from which an updated key is produced. A systematic analysis of all 20 species based on morphological and geographical distribution traits obtained from literature represents the first phylogenetic review of the genus.

Three new species and one new record of Torrenticolidae (Acari, Hydrachnidia) from Wuyishan with an updated key for Chinese fauna

New data of Torrenticolidae Piersig, 1902 are presented in this paper from Wuyishan National Nature Reserve, P. R. China. Three new species, Torrenticola suptilisrostrum Gu & Guo sp. nov., Torrenticola spinextension Gu & Guo sp. nov. and Torrenticola wuyiensis Gu & Guo sp. nov. are described and illustrated in detail, and one new record for Chinese fauna is given, Torrenticola dentifera Wiles, 1991, which was originally described from Malaysia. In addition, an updated key is provided to all species of Torrenticolidae in China.

Chaco ansilta new species from Mendoza province, Western Argentina (Araneae: Nemesiidae).

A new species of Chaco Tullgren, 1905 is described and illustrated from the Andean foothills of Mendoza province, western Argentina. This is the tenth species of the genus and the first record of Chaco in Mendoza. An updated key is presented for all Chaco species. The cladistic analysis based on a previously published morphological character matrix resulted in the consensus tree: (C. obscura, C. tucumana, C. castanea, (C. socos + C. tigre) (C. tecka (C. sanjuanina (C. Patagonia + C. ansilta sp. nov.)))).

A new species of the genus Loricula Curtis from central Honshu, Japan (Heteroptera: Microphysidae).

A new species of the little known microphysid genus Loricula Curtis (Microphysidae) is described, based on eleven female specimens recently found from Honshu, Japan. These individuals were collected on tree barks or trunks of broadleaf forest. An updated key is provided to aid in identification of adult females of the Japanese Loricula species.

Gaharitrema droneni n. gen., n. sp. (Digenea: Zoogonidae) from the Pudgy Cuskeel, Spectrunculus grandis (Ophidiiformes: Ophidiidae), from Deep Waters Off Oregon, with Updated Keys to Zoogonid Subfamilies and Genera.

Gaharitrema droneni n. gen., n. sp. (Digenea: Zoogonidae: Lepidophyllinae) is described from the intestine of the pudgy cuskeel, Spectrunculus grandis (Günther, 1877) (Ophidiiformes: Ophidiidae), collected at 2,800 m depth from the northeastern Pacific Ocean off Oregon. The new genus is distinguished from BrachyenteronManter, 1934 and SteganodermaStafford, 1904, the 2 closest lepidophylline genera, and from 4 other zoogonid genera erected since 2007, the last major revision of the family, by a combination of diagnostic features including a pyriform or spindle-shaped body, smooth testes and ovary, narrow ceca that reach with the vitellarium into the hindbody, an unspecialized ventral sucker, non-filamented eggs, a claviform cirrus pouch, and an unpocketed ejaculatory duct and metraterm, and the new genus lacks circumoral spines. We present updated keys to the 3 subfamilies of the Zoogonidae Odhner, 1902, as well as to the genera of the Cephaloporinae Yamaguti, 1934 and the Lepidophyllinae Stossich, 1903. A listing of the parasites known from S. grandis also is presented. This study documents the third family of digeneans (Zoogonidae) known to parasitize S. grandis, and it is a new host record (i.e., the first zoogonid reported from this host species). We discuss the relatively impressive presence of the Zoogonidae and their hosts within the deep sea. Specifically, of the 35 genera we recognize within this digenean family, 14 (40%) have deep-sea representatives. At least 37 species within 27 genera and 19 families within 11 orders of deep-sea fish are known to harbor zoogonids. Furthermore, of the 37 known deep-sea fish species parasitized by zoogonids, only 5 (13.5%) harbor 2 or more zoogonid species; the remaining 32 (86.5%) harbor only 1 parasite species each, indicating strong host specificity. Finally, the dietary ecology of S. grandis is presented, allowing us to speculate that Gaharitrema droneni may be utilizing gastropods and polychaetes as well as S. grandis to complete its life cycle in the deep sea.

Austrolimnius cleidecostae, a new species of riffle beetle (Coleoptera: Elmidae) from Brazil with habitat notes and updated key of the Brazilian species of the genus

Austrolimnius cleidecostae sp. nov. is one of the smallest species of Elmidae from the Neotropical region. The new species is described and illustrated based on male and female specimens. This species represents the first record in Elmidae of mandibles with an articulated, sclerotized process on inner subapical edge. The specimens were collected from streams in the Atlantic rainforest of São Paulo and Santa Catarina, and habitat notes are given. An updated key for the Austrolimnius Carter & Zeck, 1929 of Brazil is provided. Austrolimnis browni Hinton, 1971 and A. musgravei Hinton, 1939 are recorded for the first time from Brazil.

ДЕЯКІ АСПЕКТИ ПРОФЕСІЙНОЇ КОМПЕТЕНТНОСТІ НА РІВНІ ВИВЧЕННЯ НАВЧАЛЬНОЇ ДИСЦИПЛІНИ “СВІТОВІ МОДЕЛІ ТА СТАНДАРТИ ПІДГОТОВКИ ФАХІВЦІВ СОЦІАЛЬНОЇ СФЕРИ”

The article highlights the problems of the competence approach in the higher education system. The author analyzes the conceptual issues of studying the peculiarities of training specialists in the social sphere in different countries of the world in the framework of studying the masters specialty “Social work” of the discipline “World models and standards of specialists in the social sphere training”. The article defines the purpose and objectives of the discipline “World models and standards of specialists in the social sphere training”. The author analyzes the content of the concept “competence”. The author focuses on integrational changes in education in a global context. The article analyzes competences and competences in accordance with the Framework Program for Updated Key Competences for Lifelong Learning, established by the European Parliament and the Council of the European Union on 17 January 2018. The author analyzes personal, social and educational competences, characterizes basic knowledge, skills and attitudes in accordance with this competence. The article analyzes the content of the definition “competence” in the scientific and practical perspective. The article describes the concept “scientific research competence”. The author defines the content of professional competences on the basis of the discipline “World models and standards of specialists in the social sphere training”. The article focuses on the integration of theoretical knowledge and practical experience of training social specialists in the process of developing methodological recommendations for the implementation of such experience in the system of training of relevant specialists in Ukraine as a key competence of the discipline “World models and standards of specialists in the social sphere training”. The author recommends to take into account the conceptual principles of formation of professional competencies of social sphere specialists at the level of study of the discipline “World models and standards of specialists in the social sphere training” provided that they are integral characteristics.

A review of the leafhopper tribe Agalliini (Hemiptera: Cicadellidae: Megophthalminae) with a revised key to the known Pakistani genera and species

The tribe Agalliini is reviewed from Pakistan with additional description and illustration of a new record Anaceratagallia pararobusta (Pruthi) 1936. An updated checklist and keys are given to distinguish all the genera and species of the tribe Agalliini from Pakistan.

Anonymous and Updatable Identity-Based Hash Proof System

In EUROCRYPT 2002, Alwen et al. demonstrated that an identity-based hash proof system (IB-HPS) can be used to generate an identity-based encryption (IBE) scheme, which is secure against partial leakage of the decryption key of the target identity. However, in many real-world applications, the leakage is normally unbounded, and an adversary could violate the security of such cryptography schemes by performing continuous leakage attacks. Therefore, cryptography schemes are desirable to maintain their claimed security even in the continuous leakage setting. In this paper, we first design an improved IB-HPS called updatable IB-HPS (U-IB-HPS), which has an additional key update algorithm to embed some fresh randomness into the user's private key, ensuring that enough entropy is maintained in the updated keys. Then, we further use the U-IB-HPS to propose a generic construction of continuously leakage-resilient IBE schemes. Finally, an instantiation of the U-IB-HPS with anonymity is presented. As a result, our construction delivers an anonymous IBE scheme that is secure against continuous leakage of user's private key. The security of our proposed scheme has been proved in the random oracle model under the classic decisional bilinear Diffie–Hellman assumption, which is a standard static security assumption.

New southern African species and a revalidation in the dung beetle genus Gyronotus van Lansberge, 1874 (Scarabaeidae: Scarabaeinae) with an updated key.

Three new species are described in the genus Gyronotus van Lansberge, 1874 (Scarabaeidae: Scarabaeinae), from upland grasslands of South Africa. They are Gyronotus dracomontanus Deschodt Davis, new species, Gyronotus ovalis Deschodt Davis, new species and Gyronotus kearneyorum Deschodt Davis, new species. The South African coastal forest species, Gyronotus marginatus Péringuey, 1888, status revised, is removed from synonymy with Gyronotus pumilus (Boheman, 1857) and revalidated at species level. An updated key to all South African and eSwatini species is provided.

A new species of Ampharete (Annelida: Ampharetidae) from the West Shetland shelf (NE Atlantic Ocean), with two updated keys to the species of the genus in North Atlantic waters

Ampharete oculicirrata sp. nov. (Annelida: Ampharetidae) is described from samples collected by the Joint Nature Conservation Committee and Marine Scotland Science, in the West Shetland Shelf NCMPA in the NE Atlantic. This species is characterised by a very small body size, thin and slender paleae, twelve thoracic and eleven abdominal uncinigers, presence of eyes both in the prostomium and the pygidium, the latter provided with a pair of long lateral cirri. The external micro-morphology of the new taxon was studied using scanning electron microscopy and compared with species described or reported from the North Atlantic. Two complementary keys to all species of Ampharete in the area are also provided.