Terminal Spike Research Articles

Inferring the Magnetic Field from the Rayleigh–Taylor Instability

By extending the potential approach of Layzer and Goncharov to the magnetohydrodynamics equations, we find the nonlinear solutions to the single-mode Rayleigh–Taylor instability subjected to uniform magnetic fields at various inclinations. This allows us to derive the analytical prediction of the terminal bubble and spike velocities at arbitrary Atwood numbers, which are assessed against various 2D and 3D direct numerical simulations. Contrary to the linear phase, where the magnetic field inhibits or delays the instability, the growth rate may be enhanced in the nonlinear regime, exhibiting velocities faster than the Alfvén speed. This sheds light on the importance of the nondimensional number expressing the competition between the magnetic and buoyancy effects. Conversely, we show how the orientation and the intensity of the magnetic field can be simply inferred from these solutions.

Comparison of single event effect on cascoded low noise amplifier performance metrics for two different frequencies

This manuscript examines the impact of single event effects (SEEs) on the well-known cascoded low noise amplifier (LNA) topology connected with an inter-stage inductor sandwiched between the common source (CS) and common gate transistors for boosting the LNA parameters (i.e., gain, etc). In this article, we have considered that the LNA operates at two different frequencies, such as 10 and 30 GHz, in a radiation-prone environment. The effect of SEEs is analyzed in two ways: (i) non-applying a RF input with dc voltage only, and (ii) applying a RF input with dc bias voltage. The first analysis uses basic integration to evaluate the collected charge (QCollected) for a drain terminal momentary current spike with a suitable time period, and the second analysis estimates the LNA output discontinuity (distortion) using a spectrogram (short-time FFT) to determine the radiation strikes on the cascoded LNA. The collected charge is calculated in the temporal analysis, and the discontinuity of LNA’s RF output is analysed using the spectrogram in the frequency domain analysis. From the temporal and frequency analysis, the LNA that operates at a lower frequency (10 GHz) provides more discontinuity in LNA output (causing more disturbance) than the LNA that operates at a higher frequency (30 GHz).

Non-Destructive Classification of Paddy Rice Leaf Disease Infected by Bacterial and Fungal Species Using Vision-Based Deep Learning

Rice is a plant with rounded hollow articulated culms, flat, well-attached leaf blades, and terminal spikes. Its cultivation and consumption shape the culture, diet, and economy of different groups, especially in Asia. However, farmers suffer great financial losses each year due to rice disease. Therefore, the identification and classification of rice diseases are very important. Prompt, timely, and accurate disease diagnosis prevents product loss and improves crop quality. This study focuses on the classification of whether rice paddy leaf is normal or has a disease (one of the following: bacterial leaf blight (BLB), bacterial leaf streaks (BLS), bacterial panicle blight (BPB): heart, downy mildew, hispa, and rice tungro disease (RTD)) using deep learning-based algorithms such as EfficientNet-b0, MobileNet-v2, and Places365-GoogLeNet. The best model for this simulation was found to be EfficientNet-b0 with an average accuracy of 97.74%.

The Occurrence of the Strongylid Nematodes, Kalicephalus viparae viparae (Nematoda: Diaphanocephalidae), in Viper Snakes, Macrovipera lebetina (Reptilia: Viperidae), Southwestern Iran.

ancylostomatid Kalicephalus spp. is the common parasitic intestinal nematode of reptiles. West-Asian blunt-nosed viper is a venomous snake found in extensive areas of Iran. From June to September 2017, two dead viper snakes were referred to a parasitology laboratory and examined for intestinal parasites. Several white elongated roundworms were collected and fixed to identify under light and scanning electron microscopes (SEM) based on morphological and molecular characteristics. For the molecular survey, some parts of the identified worms were extracted and the ITS of nuclear ribosomal DNA (rDNA) was amplified by polymerase chain reaction (PCR). Five roundworms were found in one snake and three worms with similar morphological characteristics in another one. All the collected female hookworms were taxonomically identified as Kalicephalus viperae viperae. The SEM findings showed the head was small and had three dorsal, ventral, and middle circumoral papillae with a spike-like process on the median papilla of K. viperae. Moreover, the buccal capsule was bivalvular and included two lateral valves consisting of several chitonid pieces. The tail of the female worm was slim and long with a blunt end and had a terminal spike at its end. In the molecular survey, the ITS of rDNA amplified at about 850 bp was identified as K. viperae. The ITS gene rDNA phylogeny analysis of the K. viperae sequence showed that the isolated species had high similarity to Ancylostoma species from around the world and is close to Ancylostoma braziliense with 88% discrepancies in the phylogenetic tree. The morphological characteristics and a large part of K. viperea viperea rDNA nucleotide sequence were reported in viper snakes for the first time in the world and in Iran.

Spirocamallanus delirae n. sp. (Nematoda, Camallanidae), a parasite of Propimelodus eigenmanni (Siluriformes: Pimelodidae) from the Brazilian Amazon.

A new species of Spirocamallanus Olsen, 1952 (Camallanidae), is described based on specimens found parasitizing Propimelodus eigenmanni (Siluriformes), an Amazonian fish. The new species has buccal capsule with 15-19 spiral ridges, males with caudal alae supported by 3 pairs of precloacal and 6 pairs of postcloacal papillae, and two terminal spikes on tail end, and females with a digitiform projection ending in two small spikes on tail end. The new species shares characteristics with a group of Neotropical Spirocamallanus that are characterized by the presence of caudal alae, 3 pairs of precloacal papillae, unequal spicules and the presence of spines on the tail tip of males. Several species of this group have been reported from marine environments, in contrast with Spirocamallanus delirae n. sp., which occurs in Amazon freshwaters. Among the Brazilian congeners placed in the referred morphological group are S. rarus, S. freitasi, S. macaensis, and S. halithophus, the last two being parasites of marine fishes. The new species differs from S. rarus (3-4), S. macaensis (12-15), and S. halithophus (10-15) based on the number of spirals in the buccal capsule and from S. fretasi based on the morphology of the larger spicule that is bifid in the former and undivided in the new species. The present description of Spirocamallanus delirae n. sp. adds new data to the biodiversity of parasites from freshwater siluriform catfish in the Neotropical region.

PD Characteristics and Parameter Extraction for EPR Cable Terminal in EMUs With Spike Defect at Low Temperature

Ethylene propylene rubber (EPR) cable terminals are widely used in high-speed railway trains. In the alpine environment, partial discharge (PD) and even breakdown failures caused by spike defects frequently occur in EPR cable terminals. To study the discharge development of cable terminals with spike defects in alpine regions, EPR cable terminal test samples with spike defects were made, and a low-temperature PD test system was built to simulate the environmental conditions in alpine regions. The characteristics of the lower PD spectrum were analyzed, and the influence mechanism of low temperature on the discharge activity was analyzed combined with the scanning electron microscope (SEM) scan. The research results show that the discharge development of the terminal spike defect can be divided into three stages: S1~S3. In S1 stage, the degree of PD at –30°C is weaker than that at 20°C dues to the low diffusion ability and weak polarization effect of carriers. In S2 and S3 stages, with the continuous discharge, low temperature makes the deterioration tolerance of ethylene propylene rubber material decrease more seriously, which promotes the development of discharge. The discharge phase interval is larger and the discharge activity is more intense at –30°C than at 20°C, and the breakdown time point is 11.6% earlier. By studying the characteristics of the spectrum, it is found that the deviation of PD φ- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q_ave</i> spectrum at –30°C from positive to negative is an important signal before the critical breakdown of cable insulation, which can provide a reference for judging the severity of terminal spike defects at low temperature.

The oribatid mite subgenus Metabelba (Pateribelba) (Acari, Oribatida, Damaeidae): redescription of M. (P.) filippovi and description of two new species

ABSTRACT Metabelba (Pateribelba) filippovi, a large species of Metabelba known from the Transcaucasus and Caspian areas, is redescribed on the basis of material from Arasbaran forest (East Azerbaijan, North-West Iran). A new, closely related species, M. (P.) abkhasica Kolesnikov & Miko sp. nov., is described on the basis of newly collected material from Abkhaziaand and an individual from the collection of Bulanova-Zachvatkina (Abkhazia). The two species form an easily distinguishable species group, characterized by unusually-shaped notogastral setae having a sharp terminal spike. Another new species, Metabelba (Pateribelba) stepposa Kolesnikov & Miko sp. nov., belonging to the M. sphagni group, is described from Kazakhstan steppes. Variability and similarities of these three species are discussed together with broader relations within the genus Metabelba. http://www.zoobank.org/urn:lsid:zoobank.org:pub:A29C8AEA-9E88-40FE-B14F-686B5FBD779E

Effect of collisions with a second fluid on the temporal development of nonlinear, single-mode, Rayleigh-Taylor instability.

Goncharov's [Phys. Rev. Lett. 88, 134502 (2002)0031-900710.1103/PhysRevLett.88.134502] nonlinear model of a single-mode Rayleigh-Taylor instability (RTI) is investigated for a partially ionized plasma in a predominantly neutral background. Terminal bubble and spike velocities are derived from the nonlinear equationsin the case where the RTI dynamics is dominated by collisions between neutrals and ions. Direct numerical simulations are used to justify the use of Goncharov's model in this regime and observe its limitations.

Lepidagathis mahakassapae sp. nov. (Acanthaceae: Barlerieae) from the high elevated Lateritic Plateau of northern Western Ghats of Maharashtra, India

Lepidagathis mahakassapae sp. nov., a monocarpic and endemic species of Acanthaceae, is described from Western Maharashtra, India. The new species is allied to L. sabui from Konkan, Maharashtra, but differs by having oblanceolate acuminate leaves, pubescent terminal elongated spikes, large floral but small sterile bracts and lanceolate broader segment of the bracteole. The stems of L. mahakassapae grows up to 250 cm in length while a few other prostrate species grows up to this length. Illustrations and colour photographs are provided for ease of identification.

Carex maolanensis (Cyperaceae), a new species from Guizhou, China

Carex maolanensis, a new species of Cyperaceae is described and illustrated from Guizhou, China. The new species belongs to sect. Decorae, and it is similar to C. jizhuangensis, but differs in having short rhizome, 3–7 spikes per node, terminal spikes androgynous, female glumes awned. The morphology of perigynium and achene of C. maolanensis and C. jizhuangensis is compared. According to the IUCN Red List criteria, it may be turned out to Endangered (EN) or Vulnerable (VU), however, for the present, it is better to be classified as Data Deficient (DD) because the field survey for the species is necessary. A revised identification key to the species of sect. Decorae from China is provided.

Description of Ruehmaphelenchus taedae n. sp. (Nematoda: Aphelenchoididae) found in Loblolly pine logs from the USA

Summary Ruehmaphelenchus taedae n. sp., isolated from Loblolly pine logs (Pinus taedae L.) from the USA, is described and figured. It is characterised by a relatively slim body (a = 42 and 43 for males and females, respectively), three lines in the lateral field, male spicules relatively small (12-18 μm) with high and dorsally bent condylus and weakly developed rostrum, bursal flap absent, short tail possessing a long terminal spike ending in a bluntly rounded tip and 8.7-13.3 μm long, vulva positioned at ca 83% of body length, vulval flap absent, vulval lips slightly protruding, post-vulval uterine branch extending for less than half of vulva to anus distance, and female tail conoid, ca 3-4 anal body diam. long, with 13.7-18.5 μm terminal projection. The new species can be separated from all other species of the genus by the male tail possessing a long terminal spike and the more anterior excretory pore. Detailed phylogenetic analysis based on 28S D2-D3 region sequences confirmed the status of this nematode as a new species.

Characterization and Genomic Analysis of Escherichia coli O157:H7 Bacteriophage FEC14, a New Member of Genus Kuttervirus.

Escherichia coli O157:H7 is an important foodborne pathogen that has become a major worldwide factor affecting the public safety of food. Bacteriophage has gradually attracted attention because of its ability to kill specific pathogens. In this study, a lytic phage of E. coli O157:H7, named FEC14, was isolated from hospital sewage. Transmission electron microscopy analysis showed that phage FEC14 had an isometric head 80 ± 5nm in diameter and a contractile tail whose terminal spikes present an umbrella-like structure. Phage FEC14 revealed 158,639bp double-stranded DNA, with the G+C content of 44.6%, 209 ORFs and four tRNAs. Genome DNA of FEC14 could not be digested by some endonucleases. Many of the features of phage FEC14 are very similar to those of the newly classified genus "Kuttervirus", including morphology, genome size and organization, etc. Phage FEC14 is proposed to be a new isolate of genus "Kuttervirus" within the family Ackermannviridae, moreover, the endonuclease resistance of phage FEC14, has priority over other genera of bacteriophages for its use in biocontrol of foodborne pathogens.

&lt;p&gt;&lt;strong&gt;&lt;em&gt;Carex ledongensis &lt;/em&gt;(Cyperaceae), a new sedge from Hainan Isl. Of South China&lt;/strong&gt;&lt;/p&gt;

A new species of Carex sect. Mitratae, C. ledongensis, is described and illustrated from Hainan, South China. The new species is similar to C. pseudotristachya but differs from the latter in its leaves much longer than culms, inflorescence with 3 spikes, terminal spike with 1.5 cm long peduncle, lateral spikes bisexual, perigynia fusiform, 6–8 mm long, and nutlets brownish black, 5–6 mm long.

Phylogenetic position of Carex splendentissima, a Korean endemic sedge (Cyperaceae)

Carex splendentissima U. Kang & J. M. Chung, endemic to the Korean peninsula, is characterized by staminate terminal spikes and glabrous elliptic perigynia. Based on its broad leaves, androgynous spikes, and tri-stigmatic features, the species has been placed in Carex sect. Siderostictae Franch. ex Ohwi, an East Asian section and a basal group in the genus. To clarify the monophyly and phylogenetic position of the species, a molecular study using the internal transcribed spacer region of nuclear ribosomal DNA and chloroplast DNA (trnL-F) data was conducted. The DNA sequence data of ten taxa in sect. Siderostictae and closely related taxa (two taxa in sect. Surculosae) with outgroups were analyzed based on maximum parsimony and maximum likelihood (ML) criteria. In the analyses, C. splendentissima was monophyletic and placed within the Siderostictae clade (sect. Siderostictae + two species of sect. Surculosae), forming a clade with C. ciliatomarginata and C. pachygyna (endemic to Japan). The clade (C. splendentissima + C. ciliatomarginata + C. pachygyna) shows evidence of diploidy. Furthermore, C. splendentissima is a sister to C. ciliatomarginata in the ML tree, and the two taxa have staminate terminal spikes. This study also updates the distribution of C. splendentissima and provides keys to the four Korean taxa in sect. Siderostictae. To conserve the endemic species C. splendentissima, further research on its genetic and ecological features should be conducted at the population level. Keywords: Carex, Carex splendentissima, endemic plant, Cyperaceae

An allelic based phenological model to predict phasic development of wheat (Triticum aestivum L.)

We developed a photoperiod-corrected thermal model that can predict wheat phenology based solely on the combination of photoperiod (Ppd) and vernalisation (Vrn) alleles to identify the phenological suitability of germplasm across the cropping region in southern Australia.More than 200 wheat genotypes that vary in combinations of Ppd and Vrn alleles were grown at 17 locations spanning 11° Latitude, thus providing a wide range in temperature and daylength gradients. The phenological sensitivities of a genotype to varying basic temperature, photoperiod and vernalisation requirement was adjusted via optimisation to minimise the least square difference between the measured and predicted dates of both terminal spike (TS) and flowering (AN).The model predicted dates of TS and AN to within 5 days of the field values. Information was used to identify the alleles required to achieve a wheat ideotype defined in a previous study. The optimum allelic combinations required to target the optimum flowering period for different locations when sown on different dates were also identified. The use of allelic based phenological models has the potential to reduce the costs to breeding programs and accelerate the release of better adapted germplasm to new and changing environments.

Effect of different land-use on occurrence and morphological traits of Carex buxbaumii (study from Biebrza National Park, Poland)

Carex buxbaumii is rare sedge of moist to wet meadows, marshes and fens. The population trends and detailed habitat requirements of this species remain unknown. In Poland, C. buxbaumii belongs to EN category of IUCN, while is even more endangered in other European countries. The knowledge on this species is limited, but probably it needs active protection for its maintenance. It is also known that plants respond morphologically to changes in the site conditions which may help to determine the ways of effective method of their conservation. Therefore, we examined the frequency and morphology of Carex buxbaumii growing in a sward of fen-grasslands i) abandoned for 15 years, ii) mowed, or iii) grazed by Konik horses. The description of the occurrence and of the morphological reaction to the differentiation in land–use type of C. buxbaumii is presented against the background of changes in vegetation cover that occurred in 2010–2016 in the examined fen-grassland.There was stated that C. buxbaumii grew on peat soils, of high content of organic matter and Ca+2. The type of land-use significantly differentiated both the frequency and morphology of C. buxbaumii. In the mowed site C. buxbaumii grew as an element of the Molinion vegetation and appeared there with 100% frequency. The individuals growing in the mowed site had the longest shoots, the longest inflorescence brackets, and the longest terminal spikes. In the site grazed by Koniks, C. buxbaumii was a component of Scheuchzerio–Caricetea nigrae vegetation, while its frequency of C. buxbaumii was 87%. The shoots there were the shortest, and in general, the morphology was the most differentiated. In the abandoned site C. buxbaumii abundance amounted 46%, and the individuals were smaller than those under the mowing regime but larger than those grazed by Koniks. In that site, the previous vegetation with high proportion of the Molinion and Phragmitetea species was replaced by Alnetea glutionosae vegetation, represented mainly by trees and shrubs. We have shown that the best conditions for the development of the C. buxbaumii population in the examined fen-grasslands are created under an extensive mowing regime.

Morphological and anatomical evidence supports differentiation of new interspecific hybrids from native Spartina maritima and invasive S. densiflora (Poaceae, subfamily Chloridoideae)

Interspecific hybridization is a major mechanism for generating evolutionary novelty in plants. Halophytic Spartina species are often abundant in coastal salt marshes around the world, and they frequently hybridize. Despite a large body of knowledge on the ecology and evolution of Spartina species, taxonomic resources for distinction of complex taxa in the genus are scarce. The general aim of this study was to characterize parental species S. maritima (native) and S. densiflora (invasive) and their reciprocal hybrids formed in the Gulf of Cadiz (Southwest Iberian Peninsula). Our approach was to quantify and compare morphological and anatomical characters of tufts, culms, leaves and inflorescences and the limits of their variation in different ecological settings. Our results document discriminating trait variables from populations of both hybrids that can be used to distinguish them from their parental species and each other. From these findings and the verification of type specimens, we describe two new nothotaxa, Spartina × onubensis subsp. onubensis and Spartina × onubensis subsp. tartessiana, and develop taxonomic keys for identification of the four studied taxa. Floral traits such as the length of the terminal spike, the spikelet and its glumes and lemma allow us to differentiate S. densiflora (with lower values) from the other three taxa. The presence of exerted stamens, shorter culms and shorter leaf blades separated S. maritima from both hybrids. Each hybrid can also be distinguished since S. × onubensis subsp. onubensis develops more spikes per inflorescence and consistently has longer leaves than S. × onubensis subsp. tartessiana.

New Host and Locality Record of Parapharyngodon Japonicus (Nematoda: Oxyuroidea) from the Egyptian Changeable Lizard Agama Mutabilis (Agamidae): A Light and Scanning Electron Microscopy.

SummaryParapharyngodon (Oxyurida) is a lizard gastrointestinal nematode parasite with a life cycle including lizards as main hosts. However, some species are known to parasitize anurans. In the present study, P. japonicus isolated from the large intestine of the Egyptian changeable lizard, Agama mutabilis was described and illustrated. Forty five specimens of these animals were collected from south Sinai desert, Egypt during the period from May to September 2017. After necropsy, the body was opened by a longitudinal incision from vent to throat, and the gastrointestinal tract was removed. The esophagus, stomach, small and large intestines were examined separately for helminthes. The recovered nematodes were examined by light and scanning electron microscopy. Thirty six specimens (80.0 %) were found to be naturally infected. The parasite was robust with prominent cuticular transverse annulations. Mouth surrounded by three bilobed lips, each with tiny labial papillae. Three pairs of caudal papillae were observed in male worms; 1 pair precloacal, 1 pair sublateral in cloacal opening line, 1 pair in proximal region of caudal appendage on its narrowed point. The posterior extremity beard dorsally directed caudal appendages. Females were with a conical posterior end terminated at a terminal spike. Ovaries reached esophageal isthmus but not wrapped around corpus. The parasite recorded was compared morphologically and morphometrically with the most similar species, it was found that it was most similar to P. japonicus with new host and locality records.

DESCRIPTION OF THELANDROS AEGYPTI (NEMATODA: PHARYNGODONIDAE) FROM THE EGYPTIAN SPINY−TAILED LIZARD, UROMASTYX AEGYPTIA (SQUAMATA: AGAMIDAE) IN EGYPT

Thelandros aegypti (Nematoda: Pharyngodonidae) isolated from the large intestine of the Egyptian spiny−tailed lizard, Uromastyx aegyptia, in North Sinai deserts, Egypt were described by means of light microscopy as a first description from this host in Egypt. 18 out of 25 (72%) of the examined specimens were naturally infected. The recovered nematodes characterized by the followings; the mouth bounded by three bilobed lips, the presence of three pairs of caudal papillae in male, the absence of gubernaculums, the post−equatorial vulva and the tail of female was suddenly constricted behind anus to form a terminal spike. Male was cylendrical with distinct posterior truncation, 3.0 (2.71-3.7) mm long; 0.24 (0.20-0.33) mm wide. Three pairs of anal Papillae were recorded; the first and the second were pre and perianal and the last pair immediately behind the rounded posterior region of the worm. The tail was narrow, sharply pointed and measured 0.052-0.072 mm in length with selender spicule measured 0.045-0.077mm long. Female was 4.34 (3.32-4.73) mm long, 0.29 (0.24-0.39) mm wide, vulva was post-equatorial, ovary was amphidelphic, the anterior part extended to the level of excretory pore and the posterior ovary extended posteriorly to the anal opening. Uteri were divergent. Egg was oval, slightly flattened and measured 65.4-79.2 μm long and 44.3-74 μm wide. The described parasite was compared with different species of the same genus from different hosts. It was found that morphometrically, the present species was more or less different from the comparable species and the only morphologically similar species was Thelandros aegypti.

A further study of Zosterophyllum sinense Li and Cai (Zosterophyllopsida) based on the type and the new specimens from the Lower Devonian of Guangxi, southwestern China

Zosterophyllum sinense Li and Cai was reported in 1977 from the Lower Devonian Cangwu Formation, eastern Guangxi of China but was rarely acknowledged by authors for its obscure original description. Based on the re-observations to the type specimens and newly-collected specimens of Z. sinense, its detailed morphological information is revealed. Zosterophyllum sinense consists of tufted rooting system and axes, sporangia with long and straight stalks and two unequal valves, are helically and loosely arranged forming the terminal spikes. By far Z. sinense is only reported from the Lower Devonian of Guangxi, palaeogeographically belonging to the Cathaysia Block, a sub-region of the whole South China Block. An Early Devonian floristic distinction is suggested by the plant components between the Yangtze and Cathaysia blocks.