Tail Shape Research Articles

Bursaphelenchus carpini n. sp., B. laciniatae n. sp. and B. cryphali okhotskensis n. subsp. (Nematoda: Aphelenchoididae) isolated from Japan

Summary Two new species and a new subspecies of Bursaphelenchus are described. Bursaphelenchus carpini n. sp. and B. cryphali okhotskensis n. subsp. were isolated from Cryphalus carpini emerged from a dead log of a Carpinus sp. collected in Ibaraki Prefecture, Japan, and from C. piceae emerged from a dead log of Abies sachalinensis collected in Hokkaido, Japan, respectively. Meanwhile, B. laciniatae n. sp. was isolated from the bark of dead Ulmus laciniata, which harboured Scolytus esuriens galleries, collected in Hokkaido, Japan. These three species phylogenetically belong to the eggersi/eremus-group clade and share common typological characters such as a relatively slender body, three-lined lateral field, male spicule with a well-developed condylus, short and wide blade (calomus-lamina complex) and lack of clear cucullus. These three species and subspecies can be distinguished from one another and their close relatives by the condylus shape, female tail shape and phylogenetic and biological characters.

Flexibility of Heterocercal Tails: What Can the Functional Morphology of Shark Tails Tell Us about Ichthyosaur Swimming?

SynopsisThe similarities between ichthyosaurs and sharks are a text-book example of convergence, and similarities in tail morphology have led many to theorize that they had similar swimming styles. The variation of ichthyosaur tail shapes is encompassed within the diversity of shark families. In particular early ichthyosaurs have asymmetrical tails like the heterocercal tails of carcharhinid sharks, while later occurring ichthyosaurs have lunate tails similar to those of lamnid sharks. Because it is not possible to measure ichthyosaur tail function, the goal of this study is to measure and compare the flexibility and stiffness of lunate and heterocercal shark tails, and to measure skeletal and connective tissue features that may affect tail flexibility. We measured flexibility in 10 species and focused on five species in particular, for dissection: one pelagic and one bottom-associated individual from each order, plus the common thresher shark (Alopias vulpinus), a tail-slapping specialist. As expected, lunate tails were overall less flexible than heterocercal tails and had greater flexural stiffness. Our results suggest that the cross-sectional profile of the skeletally supported dorsal lobe dictates flexural stiffness, but that changing tissue composition dictates flexural stiffness in the ventral lobe. We also found structural differences that may enable the tail slapping behavior of the common thresher shark. Finally, we discuss how our morphological measurements compare to ichthyosaur measurements from the literature; noting that similarities in functional morphology suggest sharks may be a good analog for understanding ichthyosaur swimming biomechanics.

Seinura caverna n. sp. (Tylenchomorpha: Aphelenchoididae), an androdioecious species isolated from bat guano in a calcareous cave

SummaryA new species of a predator aphelenchoidid,Seinura cavernan. sp., is described and illustrated. The new species was isolated from bat guano collected from a calcareous cave in Japan. The new species is characterised by its three-lined lateral field, secretory-excretory pore at the level of the posterior two-thirds of the metacorpus, a long post-uterine sac, hermaphrodite tail shape elongate conoid with a filiform tip, and an androdioecious reproductive mode. The new species is typologically and biologically close toS. steineri, but is distinguished by its longer post-uterine sac, slightly longer stylet and slightly larger median bulb. The comparisons with other morphologically similar species,i.e.,S. chertkovi,S. tenuicaudataandS. steineri, are discussed. A molecular phylogenetic analysis based on two small and large subunit ribosomal RNA genes revealed that the new species is located at the basal position of clade 3 of the Aphelenchoididae, clearly separate fromS. demani, its congener with unclear rectum and anus, which is located at the derived position, suggesting that further generic revision is necessary for the genus.Aphelenchoides liin. comb. (=Seinura lii) is proposed.

Description of Rotylenchus rhomboides n. sp. and a Belgian population of Rotylenchus buxophilus (Tylenchomorpha: Hoplolaimidae).

During a survey in the Botanical garden of Ghent University, a new species Rotylenchus rhomboides n. sp. and a population of Rotylenchus buxophilus were found. Rotylenchus rhomboides n. sp. is characterized by the presence of a rhomboid-like widening of the mid-ridge of lateral field at the level of vulva, a feature previously unknown within the genus. The population of the new species, composed only by females, has a rounded labial region with 4 to 5 annuli, robust stylet (31–37 μm long), short dorsal esophageal gland (9–19 μm) overlap of the intestine, vulva located slightly posterior to mid-body, and hemispherical or rounded tail shape with large phasmids located 3 to 5 annuli anterior to the level of anus. The hierarchical cluster analysis based on morphological features indicated that the new species closely resembles R. corsicus, R. gracilidens, and R. rugatocuticulatus. The DNA analyses of the D2-D3 of 28S rDNA, ITS rDNA, and COI mtDNA sequences of Rotylenchus rhomboides n. sp. show a close relationship with R. buxophilus, R. goodeyi, R. laurentinus, R. pumilus, and R. incultus, all of which can also be differentiated from the new species by morphological features. The combination of morphological, morphometric, and molecular characteristics confirmed the new species and the first report of R. buxophilus on yam (Dioscorea tokoro) in Belgium.

Investigation on Nose and Tail Shape Effects on Hydrodynamic Parameters in Autonomous Underwater Vehicles

Development of autonomous underwater vehicles (AUVs) which meets the design constraints and provides the best hydrodynamic performance is really an important challenge in the field of hydrodynamics. In this paper a new profile is used for designing the hull of AUVs. The nose and tail profiles of an AUV using presented profile is designed such that it can properly consider the length constraints due to arrangement of different components in the AUV body. In the current work the flow around an AUV is simulated numerically. Then, the nose and tail profiles are changed in order to investigate the contribution of each of these elements on pressure distribution over the body as well as total drag of the underwater vehicle. The effects of nose and tail profiles on hydrodynamic performance of body were evaluated for this underwater vehicle. Results showed that modified nose and tail shape improved the hydrodynamic behavior of AUVs effectively.

Molecular and morphological characterization of Paurodontoides siddiqii n. sp. (Nematoda: Hexatylina, Sphaerulariidae) associated with bark samples of Pinus eldarica from western Iran.

A new species of Paurodontoides, P. siddiqii n. sp., is described and illustrated based on its morphological, morphometric, and molecular characters. The new species is characterized by a female 550-729 μm long, lip region continuous with body contour, stylet length 7.0-8.0 μm long or c. 1.0-1.2 times the lip region diameter, lateral fields with four smooth incisures, excretory pore at 85-125 μm from anterior end located at the base of the pharyngeal bulb or posterior to it, basal pharyngeal bulb with a short posterior extension projecting into the intestine, monodelphic-prodelphic reproductive system with prominent 19-22 μm long post-uterine sac, and elongate conoid tail with a filiform terminus. The new species is compared with two known species of the genus. It differs from the type species of the genus, P. linfordi, by having slightly shorter stylet, lateral field with smooth incisures, different position of the excretory pore, and absence of male. Compared to P. latus, the new species has a shorter body, shorter stylet, different position of the excretory pore, female tail shape and absence of male. The new species was also compared with close species of the genus Paurodontus because of lateral field marked with four lines, asymmetrical stylet knobs and absence of male. Molecular phylogenetic studies of the new species using partial sequences of 18S rDNA revealed that it forms a clade with a species of the genus Ficotylus. In phylogenetic analyses using partial sequences of the 28S rDNA D2-D3 domain, the new species formed a monophyletic group with a species of the genus Veleshkinema and Sphaerularia spp. (Sphaerulariinae).

You cannot have it all: Heritability and constraints of predator-induced developmental plasticity in a Neotropical treefrog.

Many organisms have evolved phenotypic plasticity but examples of a heritable genetic basis or genetic constraints for plasticity across environments remain scarce. Tadpoles of the Neotropical treefrog Dendropsophus ebraccatus alter tail coloration and shape differently in response to fish or aquatic insect predators. To assess the genetic basis of plasticity we raised 1020 tadpoles from 17 maternal half-sib pairs (34 unique families) individually with chemical cues of fish or aquatic insects, or with cue-free control water. We used Bayesian animal models to estimate narrow sense heritability of morphology and cross-trait genetic correlations in all three treatments, heritability of plasticity in response to each predator, and genetic correlations between responses to fish and insects. Families showed remarkably different responses to predators and heritability was often high (0.45-0.75), as was heritability of plasticity itself (0.42-0.62). We detected strong negative genetic correlations for responses to each predator (-0.45 and -0.59), providing clear evidence of a limit to plasticity. Most importantly, we show that prey genotypes are constrained in their capacity to respond to different types of predators, which likely maintains genetic variation for plasticity in a temporally and spatially dynamic landscape where there is no single adaptive peak.

Impact of Stokes Shift on the Performance of Near-Infrared Harvesting Transparent Luminescent Solar Concentrators

Visibly transparent luminescent solar concentrators (TLSC) have the potential to turn existing infrastructures into net-zero-energy buildings. However, the reabsorption loss currently limits the device performance and scalability. This loss is typically defined by the Stokes shift between the absorption and emission spectra of luminophores. In this work, the Stokes shifts (SS) of near-infrared selective-harvesting cyanines are altered by substitution of the central methine carbon with dialkylamines. We demonstrate varying SS with values over 80 nm and ideal infrared-visible absorption cutoffs. The corresponding TLSC with such modification shows a power conversion efficiency (PCE) of 0.4% for a >25 cm2 device area with excellent visible transparency >80% and up to 0.6% PCE over smaller areas. However, experiments and simulations show that it is not the Stokes shift that is critical, but the total degree of overlap that depends on the shape of the absorption tails. We show with a series of SS-modulated cyanine dyes that the SS is not necessarily correlated to improvements in performance or scalability. Accordingly, we define a new parameter, the overlap integral, to sensitively correlate reabsorption losses in any LSC. In deriving this parameter, new approaches to improve the scalability and performance are discussed to fully optimize TLSC designs to enhance commercialization efforts.

Determining the Horizontal Tail Optimum Dimension of Civil Transport Class Aircraft Based on the Previous Model for Upgrading the Passengers Number

As is well known, the horizontal tail of the plane has a function to produce a force to provide stability in the longitudinal spell of the plane. The determination of the contribution of the horizontal tail to longitudinal stability on the plane can be determined by simple methods such as using Digital DATCOM software. The simulations predicted by this method can save both time and cost. Nevertheless, the determination of the horizontal tail volume ratio can still be taken into further calculation so that the horizontal tail of the aircraft to work optimally. Using the analytic calculation of the aircraft equation of motion, the value of the horizontal tail volume ratio on the plane can be determined. The value of this horizontal tail volume ratio can be used as a reference to modify the area of the horizontal tail dimension of the aircraft. The calculation results show that the area of the horizontal tail of the aircraft can be reduced to 13.16 m2 and the dimensions for the new horizontal tail shape can be determined by considering the aspect ratio and taper ratio of the reference design.

Intra-specific morphological and morphometric variability of Radopholus similis (Cobb, 1893) Thorne, 1949

All the root inhabiting migratory endoparasitic nematode populations of Radopholus procured from banana crop of Vellayani, Thiruvananthapuram, Kerala were identified as Radopholus similis. Heat killed females were straight to slightly ventrally curved posteriorly. Female’s head was low, rounded, continuous or slightly setoff with the body contour. Females were 500-660 µm long and were comparatively longer than males. Males had button shaped head set off by a constriction; female with three to five lip annuli, four crenate and areolated lateral incisures, stylet 14-18 µm long with rounded knobs, vulva post-equatorial (58%), sometimes with slight protuberant lips, ovary paired and equally developed, oesophageal gland overlapped the intestine dorsally, tail elongate-conoid with narrowly rounded terminus. The stylet length (µm), width of stylet knob (µm), distance of excretory pore from anterior end (µm), distance from head to basal bulb (µm), lateral field structure, shape of stylet knob, head region, position of phasmid, tail shape with its terminus, morphometric values like m%, o% and v% and a, c and c´ ratios of females were stable (CV<12%) features. There is an existence of intra-specific variability in the morphological and morphometric features of R. similis. The main morphological diversity was observed with P% of male and female, b ratio of female and stylet length, distance of DEGO from stylet base, o% and T% of male. All the root inhabiting migratory endoparasitic nematode populations of Radopholus Thorne, 1949 procured from banana of Vellayani, Thiruvananthapuram, Kerala were identified as Radopholus similis (Cobb, 1893) Thorne, 1949. A high degree of intra-specific morphometric variability was observed with regard to the total body length (µm), body width (µm), stylet length (µm), distance of dosrsal oesophageal gland orifice (DEGO) from stylet base (µm), number of lip annuli, lip height (µm), distance from head to basal bulb (µm), distance of anus from anterior end (µm), tail length (µm), anal body width (µm), distance of phasmid from tail terminus (µm), number of lateral lines, width of lateral field (µm), b ratio and P % among females of R. similis. Morphometric features like m%, o% and v% of females of R. similis showed least variability. These can be considered as the stable morphometric characters for discrimination of females of R. similis. Ratios like ‘a’ and ‘c’ of females of R. similis were found moderately variable. The morphometric feature and of male i.e. distance from head to basal bulb (µm) was found least variable; while number of lip annuli and spicule length (µm) were moderately variable.

First Description of the Tadpole ofTheloderma gordoni(Anura: Rhacophoridae) from Vietnam

Abstract Here we describe the tadpoles of Theloderma gordoni. These tadpoles can be distinguished from other members of the genus Theloderma by having the combination of the following characters: total length (50.1–54.5 mm, stages 28–33); tail shape (abdominal and dorsal fins with a gradual tapering toward the anterior and posterior portions, without an abrupt tapering in the posterior portion); number of marginal papillae in one row on the oral disc (51–55); degree of pigmentation (body dorsally and ventrally practically black, with a slight bluish tint). We also include a comparative analysis and thorough review of tadpole descriptions of other Theloderma.

Effects of Yellow Sea Cold Water Mass on marine nematodes based on biological trait analysis

The Yellow Sea Cold Water Mass (YSCWM) is a seasonal hydrological phenomenon with significant effects on benthic animals. Based on a range of biological traits, including feeding type, tail shape, adult body length, body shape and life history (c-p value), the biological trait analysis (BTA) of marine nematodes in the southern Yellow Sea was studied in June 2003 (summer) and January 2004 (winter) in order to reveal the effects of YSCWM on benthic animals. In terms of biological traits composition of marine nematode assemblages, results of ANOSIM showed that there were no significant differences among sites inside the YSCMW area. However, for spatial distribution, marine nematode assemblages showed significant differences between sites inside and outside of the YSCWM area in terms of body shape, as there was higher percentage of nematodes with slender body shape while lower percentage with stout and long thin body shape at the sites inside the YSCWM area. Results of BIOENV analysis showed that water depth and sediment silt-clay percentage were the most important factors contributed to the differences of biological traits of marine nematode assemblages in summer, while sediment phaeophorbide content best explained the differences of marine nematode assemblages in winter. The existence of the YSCWM may provide a stable environment for marine nematode assemblages, keeping them in a continuous state during the seasonal changes. The higher percentage of nematodes with slender body may be the response to the YSCWM.

Exploiting phenotype diversity in a local animal genetic resource: Identification of a single nucleotide polymorphism associated with the tail shape phenotype in the autochthonous Casertana pig breed

Casertana is a local pig breed mainly raised in Central-South regions of Italy. Pigs of this breed are considered the descendants of the ancient Neapolitan population that largely influenced the constitution of the modern commercial pigs. The pigs of this breed are usually curly-tailed, like several other domestic pig populations. However, Casertana population shows some variability for this trait, including animals having straight tail as observed in wild boars. In this study, we run, for the first time, a genome wide association study (GWAS) comparing the curly tailed (no. = 53) and straight tailed (no. = 19) Casertana pigs to identify genomic regions associated with the tail shape phenotype in Sus scrofa. All animals were genotyped with the Illumina PorcineSNP60 BeadChip v.2. GEMMA software was used in the GWAS for which we were able to correct for stratification in the analysed cohort. A single nucleotide polymorphism (rs81439488), located on porcine chromosome 12, was significantly associated with the investigated trait. This marker is close to the SRY-box 9 (SOX9) gene that encodes for a transcription factor that is required during sequential steps of the chondrocyte differentiation pathway, notochord maintenance and skeletogenesis. As the shape of the tail could be important in relation to the problem of tail biting in pigs, the obtained results might open new perspectives for defining selection programs answering indirectly animal welfare issues. This work demonstrated that autochthonous animal genetic resources might be used to disclose genetic factors affecting peculiar traits by exploiting segregating phenotypes and genetic variability.

A morphological database for 606 Colombian bird species

Colombia is the country with the highest bird diversity in the world. Despite active research in ornithology, compelling morphological information of most bird species is still sparse. However, morphological information is the baseline to understand how species respond to environmental variation and how ecosystems respond to species loss. As part of a national initiative, the Instituto Alexander von Humboldt in collaboration with 12 Colombian institutions and seven biological collections, measured up to 15 morphological traits of 9,892 individuals corresponding to 606 species: 3,492 from individuals captured in field and 6,400 from museum specimens. Species measured are mainly distributed in high Andean forest, páramo, and wetland ecosystems. Seven ornithological collections in Colombia and 18 páramo complexes throughout Colombia were visited from 2013 to 2015. The morphological traits involved measurements from bill (total and exposed culmen, bill width and depth), wing (length, area, wingspan, and the distance between longest primary and longest secondary), tail (length and shape), tarsus (length), hallux (length and claw hallux), and mass. The number of measured specimens per species was variable, ranging from 1 to 321 individuals with a median of four individuals per species. Overall, this database gathered morphological information for >30% of Colombian bird diversity. No copyright, proprietary, or cost restrictions apply; the data should be cited appropriately when used.

Banking crises in the US: the response of top income shares in a historical perspective

This paper examines the response of income concentration in the US to the occurrence of major systemic banking crises since the beginning of the twentieth century. In doing so, the paper analyzes the shape of the upper income tail as well as the national income shares accruing to different groups within the richest decile. The findings suggest that systemic banking crises reduce income concentration within the top decile of the US pre–tax and transfers income distribution, and more generally, that the effect is highly heterogeneous across different top income groups. While the richest income group loses ground, the lower half of the top decile appears to gain in relative terms. However, evidence suggests that the estimated short-term effect of market forces stemming from banking crises can be relatively small in magnitude and even temporary in nature, as it may be quickly reabsorbed. These findings lend indirect support to the idea that only substantial changes in government policies and institutional frameworks can bring about radical changes in income distribution.

Exploiting tail shape biases to discriminate between stable and student t alternatives

SummaryThe nonnormal stable laws and Student t distributions are used to model the unconditional distribution of financial asset returns, as both models display heavy tails. The relevance of the two models is subject to debate because empirical estimates of the tail shape conditional on either model give conflicting signals. This stems from opposing bias terms. We exploit the biases to discriminate between the two distributions. A sign estimator for the second‐order scale parameter strengthens our results. Tail estimates based on asset return data match the bias induced by finite‐variance unconditional Student t data and the generalized autoregressive conditional heteroscedasticity process.

Quantifying Tail Risk with Bad Data

We document substantial practitioner interest in measures of the downside tail risk of hedge funds, such as maximum drawdown (MDD) and worst one-period loss, together with a general sentiment that volatility does not convey enough information about tail risk. We show that past observed extremes are inappropriate estimators of tail risk, and propose a better, parametric estimator that is simple to implement and needs only short return histories as input. In addition, we characterize the statistical properties of downside risk measures and show that they depend linearly on volatility. Together with evidence that tail shape does not change much across funds, this explains why extreme downside performance measures rank funds similarly to the Sharpe ratio. Finally, we note that using sample standard deviation to estimate volatility when returns have fat tails is problematic. We show that the same technique employed in the paper can be used to improve estimation of the Sharpe ratio and other measures based on volatility.

Exploring the capabilities of monochromated electron energy loss spectroscopy in the infrared regime

Monochromated electron energy loss spectroscopy (EELS) is one of the leading techniques to study materials properties that correspond to low (<5 eV) energy losses (i.e. band-gaps, plasmons, and excitons) with nanoscale spatial resolution. Recently a new generation of monochromators have become available, opening regimes and unlocking excitations that were previously unobservable in the electron microscope. The capabilities of these new instruments are still being explored, and here we study the effect of monochromation on various aspects of EELS analysis in the infrared (<1 eV) regime. We investigate the effect of varying levels of monochromation on energy resolution, zero-loss peak (ZLP) tail reduction, ZLP tail shape, signal-to-noise-ratio, and spatial resolution. From these experiments, the new capabilities of monochromated EELS are shown to be highly promising for the future of localized spectroscopic analysis.

Description of Longidorus cheni sp. n. (Nematoda, Longidoridae) from China.

Longidorus cheni sp. n., an amphimictic species recovered from the rhizosphere of Larix principis-rupprechtii and Pyracantha fortuneana in Shanxi and Beijing, China, is described and illustrated. The taxonomic position of L. cheni sp. n. among other species within the genus was elucidated using morphometric and molecular data, and phylogenetic relationships were inferred using D2–D3 expansion domains of 28S and 18S rRNA genes by Bayesian Inference (BI) method. The new species is characterised by females with a medium body size (L = 4.9–6.6 mm), a lip region slightly expanded, broadly rounded frontally and laterally, the amphidial fovea broad and symmetrically bilobed at base, odontostyle long and slender (143–168 μm), odonthophore slightly swollen at the base, tail short bluntly conoid to rounded. Guide ring located far posterior from the oral aperture (70–93 μm). Males with two ad-cloacal pairs of supplements preceded by a row of 10–14 ventromedian supplements, with robust spicules measuring 111–126 μm along the median line. Three juvenile stages were present, tail shape of J1 elongate conoid while in J2 and J3 the tail gradually becomes bluntly rounded. Codes for identifying the new species are: A6-B3-C5-D2-E2-F3-G1-H1-I2-J2-K2. Longidorus cheni sp. n. belongs to a group of species with a guide ring at the mid-odontostyle position that have a predominantly Asiatic origin. It differs from all of them by a combination of morphological characters and unique sequences of partial 18S and D2–D3 region of 28S rRNA genes. The percentage dissimilarities in partial 18S and D2–D3 28S rRNA genes of L. cheni to the closest species (L. litchii, L. fangi, L. jonesi and L. juglans) were 1.5 %–1.8 % and 16.8–18.3 %, respectively.

On the Reliability and Tightness of GP and Exponential Models for Probabilistic WCET Estimation

As computer architectures evolve, guaranteeing that Real-Time Systems’ (RTSs’) timing requirements are met through Worst Case Execution Time (WCET) upper bounds becomes increasingly difficult. Techniques such as Measurement-Based Probabilistic Timing Analysis (MBPTA) have emerged that estimate WCET bounds exceeded only with arbitrarily low probabilities (i.e., pWCETs) through Extreme Value Theory (EVT). The Peaks Over Threshold (POT) approach for applying EVT involves adjusting a tail-shaped distribution, e.g., Generalized Pareto (GP) or Exponential, to the values that exceed a carefully selected high threshold. Several works suggest that GP should be used within POT for best representing different tail shapes, while others consider the Exponential model more adequate for providing upper bounds with increased reliability. This work presents empirical reliability and tightness evaluations of the pWCET estimates yielded by the GP and Exponential models while applying MBPTA through the POT approach. It mainly provides counter-evidence to the GP model reliability and evidence of the Exponential model adequacy in this context.