Triangular Head Research Articles

Structure Design And Optimization Approach For Low RCS Screws

With the rapid development of radar stealth and detection technology, large numbers of screws and rivets have become a major factor that affecting the aircraft’s invisibility. This is because these components have a significant impact on the overall radar cross section of the aircraft, when the electromagnetic scattering characteristic of strong scattering sources is greatly reduced. By analyzing the scattering contribution of the head and body to the screw, it has been obtained that the geometric structure of the head plays a primary role in influencing the overall radar cross section of the screw. According to the scattering mechanism and stealth principle, a shape design method for the low RCS screw is proposed, and then we investigated the scattering characteristic of the octagonal, hexadecagonal, and circular head screws respectively. Furthermore, a structure optimization approach for low RCS screws is introduced which takes the angle of the incident wave into account. This has resulted in the development of a corresponding triangular screw with low detection capabilities. The simulation results show that within the operating frequency band of radar, the triangular head screw has a maximum RCS reduction of approximately 30.1dB compared to a traditional round head screw in [-90°,90°]. On average, there is a reduction of 12.6dB. The simulated results demonstrate the effectiveness and feasibility of the proposed design and optimization method for low RCS screw structures

New Genera and Species of Trigonidiidae (Orthoptera: Grylloidea) from the Mid-Cretaceous of Myanmar with a Redescription of Birmaninemobius hirsutus.

The abundance of insects in Burmese amber illustrates a highly diverse insect community from the mid-Cretaceous period; yet, records of crickets (Grylloidea) are notably scarce. In this study, we describe two new genera with three new species, Palaeotrigonidium concavoculus gen. et sp. nov., Palaeotrigonidium defectivus sp. nov., and Tricalcaratus longilineus gen. et sp. nov., based on three specimens collected in north Myanmar. These new species can be placed within the Trigonidiidae (Orthoptera: Grylloidea) by their triangular head, compound eyes that protrude in dorsal view, and a body entirely covered with robust setae, particularly noticeable in the head and pronotum; however, subfamily assignments are not possible. Another known species, Birmaninemobius hirsutus, Xu et al., 2020, from Myanmar amber is redescribed based on a new specimen and a recheck of the holotype.

Cretafrica orapensis: a new genus and species of Mycetoporinae (Coleoptera: Staphylinidae) from lacustrine deposits at Orapa Diamond Mine, Botswana

Abstract A new genus and species of staphylinid beetle, Cretafrica orapensis gen. nov. et sp. nov. is described using a single well-preserved impression fossil from an Upper Cretaceous fossil insect deposit, the Orapa Diamond Mine in Botswana. Cretafrica is placed in the extant subfamily Mycetoporinae based on its general habitus, typical sublimuloid medium-to-large body form, elongated head, visible ridge on ventral side of head under eyes, antennomeres increasing in length and width apically, scutellum with basal carina that is distinctly divided medially, elevated area along suture of the elytra, and presumably large metacoxae, and tapering abdomen. It differs from other Mycetoporinae by its triangular head and elytra with broadly rounded apico-lateral margins. A possible preservation distortion illustrates brush-like or fork-like mouthparts. The fossil insect may have been found in forest litter or fresh and rotting mushrooms at Orapa. It confirms the widespread distribution of mycetoporines with phytophagous or mycophagous lifestyles during the mid-Cretaceous. Moreover, like other described fossil staphylinids, the fossil portrays morphological stasis dating back to the Cretaceous. It further confirms the proposed punctuated equilibrium pattern of evolution.

Chiroptically active quantum nanonails.

In recent years, extensive research efforts have been dedicated to the investigation of CdSe/CdS-based quantum-confined nanostructures, driven by their distinctive properties. The morphologies of these nanostructures have been shown to directly affect their properties, an area which has proven to be an important field of study. Herein, we report a new morphology of CdSe/CdS core-shell heterostructures in the form of a 'nanonail' - a modified nanorod-like morphology, in which a distinctive triangular head can be observed at one end of the structure. In-depth studies of this morphology reveal a material with tuneable rod length and width, as well as exceptional photoluminescent properties. Following this, we have demonstrated the ability to induce chiroptical activity via ligand exchange, revealing the important role of the specific morphology, shell thickness and chiral ligand concentration in the effect of ligand induced chirality. In addition, the cellular uptake and cytotoxicity of obtained chiral nanostructures were evaluated on human lung-derived A549 cancer cells, revealing a significant enantioselectivity in biological activity. Finally, analysis on monolayers of the material demonstrate the complete absence of FRET processes. Overall, this CdSe/CdS heterostructure is another tuneable morphology of a very important nanomaterial, one which shows great advantages and a range of potential applications.

Rineloricaria quilombola: a new species of whiptail catfish (Siluriformes, Loricariidae, Loricariinae) from upper and middle Tocantins River basin, Brazil

The genus Rineloricaria comprises 69 valid species and has been considered monophyletic by some authors. The taxonomic history of Rineloricaria is quite complex, especially concerning its wide distribution and morphological plasticity that make it difficult to diagnose and describe new species. Even with the great species-richness of the genus and the huge diversity of the system, the Tocantins-Araguaia River basin hosts only three formally described species of Rineloricaria: R. hasemani, R. lanceolata, and R. osvaldoi, the former is known from lower Tocantins River, R. lanceolata widespread along Amazon basin and the last one restricts to the Araguaia River basin. Recent field expeditions and collection examination revealed an undescribed species of the genus from the upper and middle Tocantins River drainage. The new species is diagnosed among its congeners by having a greater number of premaxillary and dentary teeth (both with up to 15 vs. up to 10 in most congeners). From R. hasemani it is also distinguished by having the edge of snout straight in lateral view and absence of filaments on lower lip. It is also diagnosed from R. lanceolata by having wider cleithral width and a quite different color pattern, lacking a hyalin spot on the base of pectoral and pelvic fins; and from R. osvaldoi by having a lower head depth, triangular head in dorsal view, shorter snout length and other features.

In situ erosion measurement tools for electric propulsion thrusters: triangular laser head and telemicroscope

The lifetime of electric propulsion (EP) thrusters depends particularly on the erosion characteristics of operation relevant components, for instance, the grid hole erosion of gridded ion thrusters or the channel wall erosion of Hall effect thrusters. Here two tools for in situ erosion measurements are presented, a triangular laser head for surface profiling and a telemicroscope for high-resolution optical imaging. Both can give access to radial and axial erosion parameters. The measurements can be done in situ without the need for breaking the vacuum and dismounting the thruster, which reduces thruster testing time considerably. In situ measurements can also help to ensure reproducibility of thruster performance conditions and can improve statistics of thruster characterization. The present work describes the fundamentals of both techniques in detail, selected experimental setups are presented, their performance is characterized and critically evaluated. The capabilities and limitations related to erosion measurements of EP thrusters are, exemplary, demonstrated for a gridded ion thruster RIT-22 and a Hall effect thruster SPT-100D.

Under threat: Two new troglobitic species of Girardia (Platyhelminthes: Tricladida) from sandstone and limestone caves in Brazil

The diversity of freshwater triclads of the suborder Continenticola in the Neotropical region is poorly known, with few studies in South America. In this work, we describe two new cave-dwelling species of Girardia: G. corumbataiensis sp. nov. is described from a single sandstone cave located in an area covered by semi-deciduous vegetation, southeastern Brazil; G. nobresis sp. nov. is described from a single flooded limestone cave located in an area of Cerrado vegetation, central-western Brazil. Specimens of G. corumbataiensis sp. nov. have a slight pigmented dorsal surface with highly triangular head and two eyes, whereas specimens of G. nobresis sp. nov. lack body pigmentation and eyes and have pointed auricles. Girardia corumbataiensis sp. nov. shows a pear-shaped bulbar cavity with forked portions turned dorsally and a slightly bent bursal canal. Girardia nobresis sp. nov. has an ample bulbar cavity with numerous folds and an angled bursal canal. The two new species are categorized as troglobites and easily recognized by a unique combination of characters of their external morphology and copulatory apparatus. G. corumbataiensis sp. nov. occurs in a cave inserted in a protected area, but no effective action for preservation has been provided. This species is abundant in a single stream crossing the cave, which is subject to intensive visitation and control of bat populations, besides Eucalyptus plantations nearby. The type-locality of G. nobresis sp. nov., a single flooded cave near a municipal road, has no legal protection. There are impacts, such as intensive visitation for fishing and deforestation in its surroundings.

Factors influencing the removal torque of palatal implant used for orthodontic anchorage

BackgroundA non-invasive method has recently been introduced to remove osseo-integrated palatal implants by using the implantation ratchet which is designed to screw in or unscrew the implants. Although a proof of concept has been published, the torque involved to successfully explant have not been investigated so far. The aim of this study was to assess the removal torque required to explant osseo-integrated and orthodontically utilized palatal implants, and to identify potentially influencing variables.Materials and methodThirty-one consecutive patients (15 females, 16 males; mean age 24.1 ±7.4 years) with fully osseo-integrated and previously orthodontically loaded palatal implants (Orthosystem®: diameter 4.1mm/length 4.2mm/sandblasted with large grits (SLA) surface) were randomly assigned to either clockwise or counter-clockwise non-invasive explantation. The respective explantation tool with an electric torque control was placed on the abutment connection of the implant and secured by an occlusal screw.The primary outcome studied was maximal removal torque (MRT) needed to detach the implant from its socket which was recorded individually together with other potentially influencing secondary outcomes (gender, age, orthodontic loading time, use of local anaesthetics). Student’s t-test was used to contrast MRT difference for the gender, type of suprastructure, use of local anaesthetics, and rotational direction.Spearman correlations was used to investigate associations between MRT and patient’s age or duration loading time.ResultsAverage MRT (148.6 ± 63.2N/cm) using ratchet as a non-invasive removal method of palatal implant was considered safe. The triangular head fractured of palatal implant at a torque level of 300.1 Ncm. Significantly higher explantation were recorded for male patients compared to female patients (182.0 ± 63.0 Ncm vs 112.8 ± 40.8 Ncm; P=0.001). On the other side, the mean removal torque for palatal removal in clockwise direction was non-significantly different (158.3 ± 58.6 Ncm) compared to counter-clockwise direction (139.4 ± 67.9 Ncm). Neither patient’s age (p=0.324) nor loading time (p=0.214) were significantly correlated with removal torque values.ConclusionsPertinent literature on this subject is practically non-existent, as orthodontics is presumably the only discipline where implant removal represents a treatment success. Mean MRT for successful palatal implant removal was 148.6±63.2Ncm, but a large spectrum was observed (minimum 31.5Ncm, maximum 272.8Ncm). This obvious heterogeneity underlines the importance to investigate possible influencing factors. The safe and simple non-invasive method for palatal implant removal necessitates moderate, but not high torque MRTs, independently of the torque direction. The necessary MRT seems clearly influenced by gender, but less so by patient’s age or loading time.

A new approach of crenellated fronto-orbital advancement for the management of trigonocephaly: Technical note

Trigonocephaly is a craniosynostosis characterized by a premature fusion of the metopic suture associating a characteristic triangular head shape, with a frontal medial crest and hypotelorism. Various techniques have been described for its surgical treatment which is usually performed during the first year of life. However, there might be cases with a late referral, after the age of one year. One of the technical issues with a fronto-orbital advancement surgery in a child over one year of age is that there is a significant risk of persistent residual bone defects. This article describes a surgical technique of crenellated fronto-orbital advancement for correcting trigonocephaly in children over one year of age, allowing to reduce residual bone defects.

Magnetic Soft Robot With the Triangular Head–Tail Morphology Inspired By Lateral Undulation

In this article, extend the uses of a deformable structure of magnetic elastomer to develop a bio-inspired locomotion system for millimeter-scaled robots. As proposed in other researches, this material allows a possibility of the motor-less mechanism powered by magnetic field. The actuating mechanism of the robot mainly relies on the body deformation due to magnetic alignment. On the other hand, herein, the magnetic soft robot with the triangular head-tail morphology and sine-based magnetization utilizes a high degree of freedom provided by magnetic compliance for mobility in a form of lateral undulation. Under the oscillating magnetic field, dynamic torque primarily acts to the head, the tail passively waves, and the whole body propagates a series of lateral body-waves for self-propulsion in fluid, instead of pushing out surrounding fluid to make a swimming gait. We achieve the independent control of the laterally undulating robot in force-free swimming, and demonstrate its tunable body deformation to swim in various diameters of the fluid-filled tubes. A by-product of the undulation can transfer a force rate to swim through the fabric-media. By the increase of the actuating frequency, the undulating robot propels faster to retain a stable swimming in the flow. The versatilities of the robot with the proposed mechanism can be applied to serve the diverse purposes as a reliable and effective locomotion system with a minimal control. Particularly in biomedical applications, miniature soft robots with a potential mechanism for self-propulsion can contribute the great results to pursue minimally invasive treatments.

Experimental and numerical analysis of impactor geometric shape effects on steel beams under impact loading

This paper presents experimental and numerical studies about the effect of geometric shape of impactors (drop weight) at damage status on weak axis of rectangular hollow section (RHS) steel beams under impact loadings. To do so, six simply supported steel beam specimen with 2000 mm length have been tested on their weak axis from two different height of the drop weight as 1400 mm and 2000 mm respectively. The head geometry of the drop weight consisted of three different types namely rectangular (SPC#R), circular (SPC#C) and triangular (SPC#T), while the weight of the impactors was kept constant in all conditions. For numerical simulation of impact loading on steel beams, initially, three dimensional finite element models of the samples under impact loading were analyzed using Abaqus Explicit package program. To determine the effect of geometric shape of drop weight, five parameters namely displacement, acceleration, reaction forces, stress distribution and plastic strain have been considered comparatively. Displacement, acceleration and reaction forces were compared experimentally and numerically while, stress distribution and plastic strains were only compared numerically on verified finite element models. In the second part of the numerical study, the effect of geometric shape of impactors on square hollow section (SHS) beam was investigated. For this purpose, six simply supported steel beams’ FE models with 2000 mm length have been analyzed from two different height of the drop weight as 1400 mm and 2000 mm respectively. Obtained results show that the maximum deflections and acceleration have been occurred in the beams that were hit by the triangular headed impactor in both types of the section. In addition, the biggest plastic deformation and stress distribution have been observed in the tests where triangular headed impactors were used. The minimum damage and displacement have been occurred in the tests where rectangular shaped impactor have been used. To sum up, for a constant impact load, triangular head of impactor inflicts a bigger damage and plastic deformation on steel beam in comparison to circular and rectangular heads of impactors.

Multiple input multiple output dielectric resonator antenna with circular polarized adaptability for 5G applications

ABSTRACT In this paper, the concept of the circularly polarized agile, multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) structure for fifth generation (5G) new radio application in mobile terminal is presented. Two prototypes have been fabricated, namely one with cylindrical DRA (CDRA) referred as A1 and a second one with ring DRA (RDRA) named as A2. These practical realizations of dual-port MIMO antennas have been mounted on a Rogers 5870 substrate of octagonal shape with proper ground architecture. The proposed dual-port MIMO antennas have been excited with conformal probes and L-type feed network aiming to achieve circular polarization (CP). Measured impedance bandwidth of A1 and A2 are 21.2% (3.15–3.9 GHz) and 22.2% (3.12–3.9 GHz), respectively. Moreover, for both antennas low mutual coupling between ports with minimum isolation of dB over entire impedance bandwidth has been obtained by using triangular head slots in the ground plane. Measured axial ratio bandwidths in broadside direction are 5.66% (3.26–3.45 GHz) and 4.25% (3.45–3.6 GHz), respectively. Maximum gains are 7.3 and 7.2 dBi, in that order. MIMO antenna parameters such as envelope correction coefficient, diversity gain (DG), mean effective gain and total active reflection coefficient are also calculated to verify MIMO performance parameters. The proposed antennas also demonstrate CP agility with insertion of concentric cylindrical shells of different radii.

Morphometric Evaluation of Phenotypic Groups of Creole Cattle of Southern Ecuador

The breeding of creole cattle from the southern region of Ecuador, also known as Criollo Lojano, is a source of economic support and work for the communities located in the remote areas of the Andes mountains in this region. These cattle are grouped into four biotypes based on their phenotypic characteristics: Negro Lojano, Encerado, Colorado, and Cajamarca or Pintado. This study analyzes the morphometric variability of these creole cattle using least squares means (LSM) and restricted maximum likelihood Restricted Maximum Likelihood (REML) variance components. The evaluation parameters used to characterize these cattle were live weight plus 15 morphometric characteristics and nine morphometric indexes. The measurements came from 151 adult animals (28 male and 123 females). With the exception of Height at Withers (P = 0.06), the other morphometric characteristics do not show significant difference among these creole biotypes. Sexual dimorphism was found in live weight, thoracic circumference, height at withers, chest width, length of thorax, length of body, depth of thorax, depth of abdomen, length of head, and length of horns (P < 0.05). The adult Creole Lojano has an average live weight of 288 ± 12.9 kg (mean ± standard error), The Cephalic index is 45.6, the Corporal index is 115.9, the Pelvic index is 90.5, the Thoracic index is 58.3, the Proportionality index is 62.6, the Thoracic Capacity index is 2.1, the Lower Leg–Thoracic index is 9.9, the Transverse Pelvic index is 34.7, and the Pelvic Length index is 38.4. This creole bovine breed presents 4 biotypes that are similar; there are differences in the analysis with respect to sex (males are higher in 10 of the 16 characteristics analyzed); and on the basis of the indexes, this animal is small, has a triangular head, is longilinear with a long and narrow hip. It is a dual-purpose milk type with the exception of the Colorado biotype which is a dual purpose meat type.

A new superfamily, family, genus and species of marine amphipod, Protodulichia scandens, from Japan (Crustacea: Amphipoda: Senticaudata: Corophiida)

ABSTRACTIn this study, the new amphipod superfamily Protodulichioidea and family Protodulichiidae are established. Both belong to the infraorder Corophiida but is different from all known superfamilies and families. Amphipods included in the new superfamily and family are characterised by having a triangular head with large eyes, extremely long pereopod 7, and uropod 3 with a short peduncle and slender rami bearing a few robust setae. Protodulichia scandens gen. et sp. nov. is fully described here and its mast-building behaviour is also recorded.urn:lsid:zoobank.org:pub:F6613B27-D954-4E4C-86CB-9FC5E9624334

Microcephalic Newborn with Forehead Nevus Flammeus, Bulging Eyes, and Clenched Fists

A 35-day-old growth-restricted black female infant presents with a triangular head, glabellar nevus flammeus, exophthalmos, flexion contractures of hands, micro-retrognathia, and stridor (Fig, A and B). Figure. A. Glabellar nevus flammeus, exophthalmos, hypertelorism and triangular shaped head. B. Microretrognathia and anteverted nares. ### Prenatal and Birth Histories ### Presentation The infant was transferred to the NICU from an outside hospital at 1 month of age because of poor feeding, stridor, and multiple dysmorphic facial features. ### Vital Signs–Day 35 ### Physical Examination–Day 35

Trigonocephaly: Long-term results after surgical correction of metopic suture synostosis.

Premature closure and ossification of the metopic suture results in a triangular head shape called trigonocephaly and is characterized by a wedge-shaped forehead and frontotemporal narrowing. Untreated craniosynostosis may lead to increased intracranial pressure (ICP) and, thereby, impaired neurodevelopment. Over the last decades, its incidence has been increasing, currently making it the 2nd most common type of isolated craniosynostosis. Treatment consist of cranioplasty, which should be performed before the age of 1 year. The aim of this study was to evaluate the long-term surgical outcomes in children operated on for trigonocephaly. The authors reviewed 30 consecutive cases of metopic synostosis treated over a 14-year period in the Plastic Surgery Department in Polanica-Zdrój, Poland. The data was evaluated using the patients' clinical records, and preoperative and postoperative photographs. The patients showed up on a follow-up visit at a median age of 9 years and were examined by an ophthalmologist and a neurologist. The surgical outcomes were evaluated according to the Whitaker classification. In 23 patients, remodeling and the advancement of fronto-orbital skull segments was performed at a median age of 18 months and in 7 milder cases, simple suturectomy or burring of the metopic ridge was sufficient. According to the Whitaker classification, results were considered good to excellent (category I and II). Only 1 patient was included into category III. None of the examined cases were included into category IV, which would require a major craniofacial procedure, duplicating or exceeding the original operation. Neurological abnormalities were found in 12 cases and vision defects in 15 cases. Trigonocephaly is currently the 2nd most common type of isolated synostosis. Surgical treatment based on Tessier's and Marchac's modified methods provides good results in patients at the age of about 12 months and prevents the consequences of ICP increase. Primary neurological and behavioral disorders may occur, despite corrective surgery.

A new pachyrhizodontid fish (Actinopterygii, Teleostei) from the Muhi Quarry (Albian-Cenomanian), Hidalgo, Mexico

Abstract. A new genus and species – Motlayoichthys sergioi (ZooBank registration: urn:lsid:zoobank.org:pub:2C503741-2362-4234-8CE0-BB7D8BE5A236, urn:lsid:zoobank.org:act:EF5040FD-F306-4C0F-B9DA-2CC696CA349D) – from the Cretaceous (Albian-Cenomanian) of the Muhi Quarry, Hidalgo, central Mexico is assigned to the family Pachyrhizodontidae based on the presence of the inner premaxillary tooth and a few other cranial characters. Its unique suite of characters, that includes several autapomorphies supports its assignment as a new genus and species, such as the presence of a triangular head with three sides of similar lengths and with its deepest part at the level of the supraoccipital region; the lower jaw projecting anterior to the premaxilla; the ornamentation of cranial bones – especially those of the cheek region – consisting of fine longitudinal crests densely covering the bony surfaces; one or a few deep grooves on the mandibular teeth, which in addition bear acrodin tips ornamented with fine parallel striae; and the position of the dorsal fin, near the posterior margin of the cranium. Motlayoichthys n. gen., together with Michin, Pachyrhizodus, Rhacolepis, and Notelops, is part of the early radiation of pachyrhizodontoids during Albian times.

Association Between Fear and Beauty Evaluation of Snakes: Cross-Cultural Findings.

According to the fear module theory, humans are evolutionarily predisposed to perceive snakes as prioritized stimuli and exhibit a fast emotional and behavioral response toward them. In Europe, highly dangerous snake species are distributed almost exclusively in the Mediterranean and Caspian areas. While the risk of a snakebite is relatively low in Central Europe, Azerbaijan, on the other hand, has a high occurrence of the deadly venomous Levant viper (Macrovipera lebetina). We hypothesize that co-habitation with this dangerous snake has shaped the way in which humans evaluate snake species resembling it. For that purpose, we asked respondents from the Czech Republic and Azerbaijan to rank photographs depicting 36 snake species according to perceived fear and beauty. The results revealed a high cross-cultural agreement in both evaluations (fear r2 = 0.683, p < 0.0001; beauty: r2 = 0.816, p < 0.0001). Snakes species eliciting higher fear tend to be also perceived as more beautiful, yet people are able to clearly distinguish between these two dimensions. Deadly venomous snakes representing a serious risk are perceived as highly fearful. This is especially true for the vipers and allies (pit vipers) possessing a characteristic body shape with a distinct triangular head and thick body, which was found as the most fear evoking by respondents from both countries. Although the attitude toward snakes is more negative among the respondents from Azerbaijan, their fear evaluation is similar to the Czechs. For instance, despite co-habitation with the Levant viper, it was not rated by the Azerbaijanis as more fearful than other dangerous snakes. In conclusion, agreement in the evaluation of snake fear and beauty is cross-culturally high and relative fear attributed to selected snake species is not directly explainable by the current environmental and cultural differences. This may provide some support for the evolutionary hypothesis of preparedness to fear snakes.

Revisiting the fear of snakes in children: the role of aposematic signalling.

Why humans fear snakes is an old, yet unresolved debate. Its innate origin from evolutionary causes is debated against the powerful influence early experience, culture, media and religion may have on people’s aversion to snakes. Here we show that the aversion to snakes in human beings may have been mistaken for an aversion to aposematic signals that are commonly displayed by snakes. A total of 635 children were asked to rate single item images as “nice” or “mean”. Snakes, pets and smiley emoticon items were not rated as “mean” unless they displayed subtle aposematic signals in the form of triangular (rather than round) shapes. Another 722 children were shown images featuring two items and asked which item was “nice” and which item was “mean”. This context dependent comparison triggered even sharper responses to aposematic signals. We hypothesise that early primates evolved an aversion for aposematic signals in the form of potentially harmful triangular shapes such as teeth, claws or spikes, not for snakes per se. Further, we hypothesise that this adaptation was in turn exploited by snakes in their anti-predatory threat display as a triangular head or dorsal zig-zag pattern, and is currently the basis for efficient international road-danger signalling.

More than meets the eye: change in pupil shape by a mock viper

More than meets the eye: change in pupil shape by a mock viper