Blunt Tail Research Articles

Aerodynamic Performance Analysis of a Modified Joukowsky Airfoil: Parametric Control of Trailing Edge Thickness

In order to ensure the blade strength of large-scale wind turbine, the blunt trailing edge airfoil structure is proposed, aiming at assessing the impact of the trailing edge shape on the flow characteristics and airfoil performance. In this paper, a Joukowsky airfoil is modified by adding the tail thickness parameter K to achieve the purpose of accurately modifying the thickness of the blunt tail edge of the airfoil. Using Ansys Fluent as a tool, a large eddy simulation (LES) model was used to analyze the vortex structure of the airfoil trailing edge. The attack angles were used as variables to analyze the aerodynamic performance of airfoils with different K-values. It was found that when α = 0°, α = 4°, and α = 8°, the lift coefficient and lift–drag ratio increased with increasing K-value. With the increase in the angle of attack from 8° to 12°, the lift–drag ratio of the airfoil with the blunt tail increased from +70% to −7.3% compared with the original airfoil, which shows that the airfoil with the blunt trailing edge has a better aerodynamic performance at a small angle of attack. The aerodynamic characteristics of the airfoil are affected by the periodic shedding of the wake vortex and also have periodic characteristics. By analyzing the vortex structure at the trailing edge, it was found that the value of K can affect the size of the vortex and the position of vortex generation/shedding. When α = 0°, α = 4°, and α = 8°, the blunt trailing edge could improve the aerodynamic performance of the airfoil; when α = 12°, the position of vortex generation changed, which reduced the aerodynamic performance of the airfoil. Therefore, when designing the trailing edge of an airfoil, the thickness of the trailing edge can be designed according to the specific working conditions. It can provide valuable information for the design and optimization of blunt trailing edge airfoil.

Scanning electron microscopy of A scaridia galli in Gallus gallus domesticus in Lucknow, U.P, India

Background/objectives: Ascaridia galli (Schrank) is a well-known nematode parasite of poultry birds. Heavy infection causes an economic loss to the poultry farmers. Information related to its detailed morphological and anatomical structure is inadequate. A study of ultrastructure has revealed the possibility of differentiating the nematodes. Methodology: Ascaridia galli were collected from the domestic fowl (Gallus gallus domesticus) from Lucknow, UP. Scanning electron microscopy was used for the detailed identification of Ascaridia galli. Findings: Scanning electron microscopy exposed that mouth was surrounded with three trilobed lips. Internal rim of each lip was surrounded with fine teeth, and sensory papillae on the outside. Annulations of cuticle occur on the body surface, which is further divided into subannuli. Posterior end of male was pointed and curved having a precloacal sucker and anus. Females had a blunt and straight tail with an anus at ventral side. Caudal papillae and the lateral caudal alae are the tiny outgrowths which surrounds the each side of posterior opening. A sclerotized ring bounded to precloacal sucker was present. These signs of Ascaridia galli attained in the present study could be helpful in the taxonomical studies of nematode worms. Development of control strategies is very essential by understanding the host–parasite relationships. For this purpose, identification of nematode parasite will be very useful. Novelty/ contribution: The present study was designed to understand the morphology of A. galli. Therefore, these markers could be helpful in the taxonomical status of ascaridia nematode worms in domestic fowl. Keywords: Domestic fowl; A galli; Precloacal sucker; Trilobed lips; Caudal papillae; Scanning electron microscopy

UCH-L1 is a Poor Serum Biomarker of Murine Traumatic Brain Injury After Polytrauma

BackgroundSeveral serum biomarkers have been studied to diagnose incidence and severity of traumatic brain injury (TBI), but a reliable biomarker in TBI has yet to be identified. Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) has been proposed as a biomarker in clinical and preclinical studies, largely in the setting of isolated TBI or concussion. The aim of this study was to evaluate the performance of UCH-L1 as a serum biomarker in the setting of polytrauma and TBI. MethodsMultiple variations of murine TBI and polytrauma models were used to evaluate serum biomarkers. The different models included TBI with and without hemorrhagic shock and resuscitation, isolated extremity vascular ligation, extremity ischemia/reperfusion, and blunt tail injury. Blood was drawn at intervals after injury, and serum levels of neuron-specific enolase, UCH-L1, creatine kinase, and syndecan-1 were evaluated by enzyme-linked immunosorbent assay. ResultsUCH-L1 levels were not significantly different between TBI, tail injury, and sham TBI. By contrast, neuron-specific enolase levels were increased in TBI mice compared with tail injury and sham TBI mice. UCH-L1 levels increased regardless of TBI status at 30 min and 4 h after hemorrhagic shock and resuscitation. In mice that underwent femoral artery cannulation followed by hemorrhagic shock/resuscitation, UCH-L1 levels were significantly elevated compared with shock sham mice at 4 h (3158 ± 2168 pg/mL, 4 h shock versus 0 ± 0 pg/mL, 4 h shock sham; P < 0.01) and at 24 h (3253 ± 2954 pg/mL, 24 h shock versus 324 ± 482 pg/mL, 24 h shock sham; P = 0.03). No differences were observed in UCH-L1 levels between the sham shock and the arterial ligation, vein ligation, or extremity ischemia/reperfusion groups at any time point. Similar to UCH-L1, creatine kinase was elevated only after shock compared with sham mice at 4, 24, and 72 h after injury. ConclusionsOur study demonstrates that UCH-L1 is not a specific marker for TBI but is elevated in models that induce central and peripheral nerve ischemia. Given the increase in UCH-L1 levels observed after hemorrhagic shock, we propose that UCH-L1 may be a useful adjunct in quantifying severity of shock or global ischemia rather than as a specific marker of TBI.

Mild Traumatic Brain Injury in Mice Beneficially Alters Lung NK1R and Structural Protein Expression to Enhance Survival after Pseudomonas aeruginosa Infection

Mild traumatic brain injury (mTBI) in a murine model increases survival to a bacterial pulmonary challenge compared with blunt tail trauma (TT). We hypothesize substance P and its receptor, the neurokinin 1 receptor (NK1R; official name TACR1), play a role in the increased survival of mTBI mice. Mice were subjected to mTBI or TT, and 48 hours after trauma, the levels of NK1R mRNA and protein were significantly up-regulated in mTBI lungs. Examination of the lung 48 hours after injury by microarray showed significant differences in the expression of 433 gene sets between groups, most notably genes related to intercellular proteins. Despite down-regulated gene expression of connective proteins, the presence of an intact pulmonary vasculature was supported by normal histology and bronchoalveolar lavage protein levels. To determine whether these mTBI-induced lung changes benefited invivo responses, two chemotactic stimuli (a CXCL1 chemokine and a live Pseudomonas aeruginosa infection) were administered 48 hours after trauma. For both stimuli, mTBI mice recruited more neutrophils to the lung 4 hours after instillation (CXCL1: mTBI=6.3±1.3 versus TT=3.3±0.7 neutrophils/mL; Pseudomonas aeruginosa: mTBI=9.4±1.4 versus TT=5.3±1.1 neutrophils/mL). This study demonstrates that the downstream consequences of mTBI on lung NK1R levels and connective protein expression enhance neutrophil recruitment to a stimulus that may contribute to increased survival.

An experimental study of dynamics of towed flexible cylinders

In this paper, some experiments are described which were designed to illustrate the dynamical behaviour of towed flexible cylinders and to test the theory. A silicone rubber cylinder was manufactured such that it was almost neutrally buoyant when immersed in water. The cylinder was terminated by plexiglas end-pieces and was held in horizontal water flow by a length of nylon thread (towrope). Video capturing along with image processing techniques were used to measure the transverse displacement of the cylinder in the horizontal plane. For the cylinder with relatively streamlined nose and tail end-pieces, non-flexural (rigid-body), as well as flexural instabilities developed as the flow velocity was increased; shortening the towrope was not very effective for stabilizing the system, but a sufficiently blunt tail end-piece had a very significant stabilizing effect. The experimental observations are generally in qualitative agreement with the available nonlinear theory. Quantitative comparison of various quantities, e.g. the instability thresholds, between experiment and theory, based on the estimated values of some of the theoretical nondimensional parameters, is also fairly good.

Effect of vehicle configuration on the performance of a submersible pulsed-jet vehicle at intermediate Reynolds number

Recent results have demonstrated that pulsed-jet propulsion can achieve propulsive efficiency greater than that for steady jets when short, high frequency pulses are used, and the pulsed-jet advantage increases as Reynolds number decreases into the intermediate range (∼50). An important aspect of propulsive performance, however, is the vehicle configuration. The nozzle configuration influences the jet speed and, in the case of pulsed-jets, the formation of the vortex rings with each jet pulse, which have important effects on thrust. Likewise, the hull configuration influences the vehicle speed through its effect on drag. To investigate these effects, several flow inlet, nozzle, and hull tail configurations were tested on a submersible, self-propelled pulsed-jet vehicle (‘Robosquid’ for short) for jet pulse length-to-diameter ratios (L/D) in the range 0.5–6 and pulsing duty cycles (StL) of 0.2 and 0.5. For the configurations tested, the vehicle Reynolds number (Reυ) ranged from 25 to 110. In terms of propulsive efficiency, changing between forward and aft-facing inlets had little effect for the conditions considered, but changing from a smoothly tapered aft hull section to a blunt tail increased propulsive efficiency slightly due to reduced drag for the blunt tail at intermediate Reυ. Sharp edged orifices also showed increased vehicle velocity and propulsive efficiency in comparison to smooth nozzles, which was associated with stronger vortex rings being produced by the flow contraction through the orifice. Larger diameter orifices showed additional gains in propulsive efficiency over smaller orifices if the rate of mass flow was matched with the smaller diameter cases, but using the same maximum jet velocity with the larger diameter decreased the propulsive efficiency relative to the smaller diameter cases.

α5β1 Integrin-Mediated Adhesion to Fibronectin Is Required for Axis Elongation and Somitogenesis in Mice

The arginine-glycine-aspartate (RGD) motif in fibronectin (FN) represents the major binding site for α5β1 and αvβ3 integrins. Mice lacking a functional RGD motif in FN (FNRGE/RGE) or α5 integrin develop identical phenotypes characterized by embryonic lethality and a severely shortened posterior trunk with kinked neural tubes. Here we show that the FNRGE/RGE embryos arrest both segmentation and axis elongation. The arrest is evident at about E9.0, corresponding to a stage when gastrulation ceases and the tail bud-derived presomitic mesoderm (PSM) induces α5 integrin expression and assumes axis elongation. At this stage cells of the posterior part of the PSM in wild type embryos are tightly coordinated, express somitic oscillator and cyclic genes required for segmentation, and form a tapered tail bud that extends caudally. In contrast, the posterior PSM cells in FNRGE/RGE embryos lost their tight associations, formed a blunt tail bud unable to extend the body axis, failed to induce the synchronised expression of Notch1 and cyclic genes and cease the formation of new somites. Mechanistically, the interaction of PSM cells with the RGD motif of FN is required for dynamic formation of lamellipodia allowing motility and cell-cell contact formation, as these processes fail when wild type PSM cells are seeded into a FN matrix derived from FNRGE/RGE fibroblasts. Thus, α5β1-mediated adhesion to FN in the PSM regulates the dynamics of membrane protrusions and cell-to-cell communication essential for elongation and segmentation of the body axis.

Two New Species Of Aporcelaimellus (Nematoda: Dorylaimida) From The Americas

This paper provides the descriptions and illustrations of two new species of the nematode genus Aporcelaimellus (family Aporcelaimidae). Aporcelaimellus salsus sp. n. from the United States is characterized by the medium-sized body, short odontostyle, unsclerotized vulva, conical, dorsally not concave tail with distinctly separated layers of terminal cuticle. Aporcelaimellus acaudatus sp. n. from Ecuador is distinguished by the large body, sclerotized vulva and especially by the exceedingly short and blunt tail with strongly thickened inner layer of terminal cuticle.

New Species of Amphisbaena with a Nonautotomic and Dorsally Tuberculate Blunt Tail From State of Bahia, Brazil (Squamata, Amphisbaenidae)

A new species of Amphisbaena is described from Fazenda Caraibas, municipality of Mucugê, state of Bahia, Brazil, in the northern portion of the Serra do Espinhaço. The new species is a small amphisbaenian without precloacal pores, 210–213 body annuli, 12–13 tail annuli without evident autotomic site, and 14 dorsal and 14–15 ventral segments per annuli at midbody. The striking difference of this form is the presence of small tubercles on the dorsal region of its tail. This feature is unique among its congeners, although Rhineura floridana, a North American amphisbaenian, has tubercles on its tail. We suggest that the presence of tubercles on the tail of Amphisbaena sp. nov. and Rhineura floridana has arisen independently.

Two new species of Entomelas (Nematoda: Rhabdiasidae), parasites of Barisia spp. and Mesaspis spp. (Reptilia: Sauria) in Mexico

Entomelas campbelli n. sp. (Rhabdiasidae) from the lungs of Barisia imbricata and Mesaspis gadovii (Sauria) and Entomelas floresvillelai n. sp. from B. imbricata, B. herrerae and M. viridiflava (Sauria) are described and illustrated. Both species are similar to E. duellmani in the equatorial location of vulva; E. campbelli resembles E. duellmani in measurements of the buccal capsule, but differs in the shape of the tail, body length, egg size, esophagus length and tail length/body length ratio; E. floresvillelai resembles E. duellmani by possessing a blunt tail, but differs in the body length, egg size, depth of the buccal capsule, length of the esophagus and tail length/ body length ratio. Entomelas campbelli differs from E. florevillelai in the shape of the anterior end and the tail, width of the body and buccal capsule, width of the esophageal bulb, egg size and esophagus length/body length ratio. These are the second and third species assigned to New World Entomelas and the second record of the genus from Mexico.

Male development

The features that differentiate the C. elegans male from the hermaphrodite arise during postembryonic development. The major male mating structures, consisting of the blunt tail with fan and rays, the hook, the spicules and proctodeum, and the thin body, form just before the last larval molt. Male and hermaphrodite embryogenesis are similar but some essential male cell fates are already established at hatching. The male mating structures arise from three important sets of male-specific blast cells. These cells generate a total of 205 male-specific somatic cells, including 89 neurons, 36 neuronal support cells, 41 muscles, 23 cells involved in differentiating the hindgut, and 16 hypodermal cells associated with mating structures. Genetic and molecular studies have identified many genes required for male development, most of which also function in the hermaphrodite. Cell-cell interactions play a role in patterning all three of the generative tissues. Male-specific neurons, including sensory neurons of the rays, hook, post-cloacal sensilla, and spicules, differentiate at the end of the last larval stage and send out axons to make connections into the existing neuropil, greatly enlarging the posterior ganglia. The hindgut is highly differentiated to accommodate the spicules and the joining of the reproductive tract to the cloaca. A complex male-specific program generates many new muscles for copulation. The cell lineage and genetic program that gives rise to the one-armed male gonad appears to be a variation on that of the hermaphrodite.

Three species of Tobrilidae (Nematoda: Enoplida) from Li River at Guiling, China

Eutobrilus annetteae Joubert & Heyns, 1979 with its male reported for the first time, Semitobrilus pellucidus (Bastian, 1865) Tsalolichin, 1983, and Epitobrilus allophysis(Steiner, 1919) Tsalolichin, 1996 are described from the Li River at Guiling, China. The male of Eutobrilus annetteae is characterized by lots of crystalloids inside body, almost straight spicules about one anal body diameter long and seven equally sized supplements. Semitobrilus pellucidus from Guiling shows large variation in body width, position of amphids, form of buccal cavity, distance between denticles, direction of vagina, arrangement of oocytes, and shape of eggs. It is different from other populations in its shorter cephalic setae, less than 60% of head width, in its shorter tail and smaller c′ value. In males, there are 6–9 supplements, reduced and irregulary spaced. Epitobrilus allophysisis characterized by its labial setae longer than 50% of head width, small, posteriorly located ovoid amphid, single egg occupying whole space of uterus and blunt tail tip.

Four New Nematode Species From the Bothnian Bay, Northern Baltic Sea, With a Redescription of Microlaimus Globiceps De Man, 1880 (Nematoda)

Four free-living nematodes from the Bothnian Bay, the northern part of the Baltic Sea, are described as new to science. A key to the genus Eleutherolaimus Filipjev, 1922, is given. Eleutherolaimus schneideri sp. n. is characterized by unequal cephalic setae and subcephalic setae, subcephalic setae shorter than the head diameter, amphid position in junction of buccal cavity and oesophagus, long cardia and short spicules. Microlaimus limnophilus sp. n. belongs to the group of small microlaimids (shorter than 0.5 mm) and is characterized by very small teeth (dorsal tooth about 0.5 μm long) and wide body annules (2.5-3.0 μm in midbody). Prismatolaimus paraprimitivus sp. n. has a slender body (a = 56-65), outer labial setae and cephalic setae in separate circles, wide amphid (2/3 of corresponding body diameter), precloacal supplements confined to posterior body region and long tail. Halalaimus dimorphus sp. n. is recognized by long amphid, posteriorly narrow oesophagus, setose inner labial sense organs, well-separated head setae, swollen, blunt tail end. The reproductive system of Halalaimus dimorphus sp. n. is unique in showing both sperm and egg dimorphism; the spermatozoa have longitudinal striations. Microlaimus globiceps de Man, 1880 is redescribed.

Four New Species of Labronema Thorne, 1939 From Islands in the Western Indian Ocean (Nematoda: Dorylaimoidea)

Four new Labronema species are described from islands in the western Indian Ocean. L. bicuticulum sp. n., found on Mahe, Seychelles is characterized by a convex-conoid bluntly rounded tail with double cuticle. L. seychellense sp. n. from both La Digue and Mahe in the Seychelles resembles L. pygmaeum Heyns, 1963 and L. pusillum Andrassy, 1985, but can be distinguished from these species by the short, bluntly rounded tail with thickened cuticle, and the absence of lateral guiding pieces. L. malagasi sp. n. from Nosi-Komba, Madagascar, closely resembles L. mauritiense Williams, 1959, from which it differs mainly in the very short uterus without differentiated ovejector, and internal tail structure. L. brevicauda sp. n., also from Nosi-Komba, has a very short, blunt tail with the hyaline part mostly comprising more than half the tail length. It is compared with L. chilense Andrassy, 1967, from which it can be separated by the tail shape and vulva position.

Nematode parasites of Orthoporus americanus (Diplopoda; Spirobolida) from Paraguay

Three new species of the Rhigonematida (Nematoda) are described from the posterior intestine of Orthoporus americanus from Paraguay. Heth orthopori n.sp. resembles Heth hamatus Bowie, 1985 from Eumastigonus kaorinus from New Zealand in that striae posterior to the cervical collar of the females bear rows of tiny spines; it differs from this species in that all spines in the cervical collar are of approximately the same size. Rondonema nelsonae n.sp. is most similar to the type species Rondonema rondoni Artigas, 1926 from an unidentified Brazilian diplopod in that lateral spines in the cervical region of the female are conical; it differs from this species in that these spines are much smaller, and differs from all species in the genus by the shape of the tail of the male. Rhigonema carlosi n.sp. most closely resembles Rhigonema truncatum Artigas, 1926 from an unidentified Brazilian diplopod and Rhigonema subtruncatum Dollfus, 1952 from Gymnostreptus sp. from Brazil in having a short subconical tail in the female and a short blunt tail and robust arcuate spicules in the male; it differs from both species in having at least two more pairs of caudal papillae and by the shape of the distal extremity of the spicule.

Numerical analysis of supersonic base flow in the presence of thermal action on the wake

There exist several types of aircraft for which the base drag at supersonic speed is a significant fraction of the total aerodynamic drag. The base drag is determined by the low pressure in the region of the near wake formed behind the body with a blunt tail cutoff. One way to raise the pressure on the tail is to deliver heat from the combustion of fuel injected into the base region or the external inviscid flow from the surface of the body. The effectiveness of this method has already been proven experimentally; the authors of this paper seek to carry out a detailed theoretical analysis of the complex base flow when this process of drag reduction is employed.

Filarid Parasites of South Kalimantan (Borneo) Indonesia. Wuchereria kalimantani sp. n. (Nematoda: Filarioidea) from the Silvered Leaf Monkey, Presbytis cristatus Eschscholtz 1921

On the basis of morphological characteristics of adult and microfilarial stages, Wuchereria kalimantani sp. n. (Nematoda: Filarioidea) is described. The parasites were recovered from the inguinal lymph nodes and testes of silvered leaf monkeys (Presbytis cristatus) from a rubber estate, Banjar Regency, South Kalimantan (Borneo), Indonesia. Adult males are characterized by having more than 24 caudal papillae, a left spicule with a simple lamina, four pairs of sessile caudal papillae, a blunt tail, a mean overall length of 41 mm, and sheathed microfilariae with a nude tail tip; accordingly, the parasite is placed in the genus Wuchereria. This is the second species of Wuchereria described on the basis of both adult and embryonic forms, and is the first such species that has been found to infect primates naturally.

Regional Specialization of Reptilian Scale Surfaces: Relation of Texture and Biologic Role

The iridescent body scales of the fossorial uropeltid snakes produce these interference colors by keratinous ridges spaced at 2500 A. The pattern inhibits wetting of the surface and adhesion of soil particles and thus reduces friction between the snake's trunk and walls of its tunnel. The epidermal scales of the blunt tail show a sharply defined pattern of spines and ridges with convergent flutings. Dirt caught here forms a plug that protects the snake's caudal end. The sharp transition of surface textures suggests (i) that selection for each of the two roles is great, and (ii) that the interference colors of many fossorial snakes indicate that friction as well as dirt adhesion are being reduced.

Capillaria colubra sp. n. from the Oviducts of Coluber constrictor priapus

Capillaria colubra sp. n. is described from the oviducts of the southern black racer, Coluber constrictor priapus, from southern Louisiana. It is distinguished from the closely related Capillaria heterodontis by its larger size, transverse striations on the spicule and spicule sheath, and a more elaborate caudal bursalike expansion and two ventral papillae in the male. It is smaller and has a lower ratio of anterior to posterior body regions than Capillaria longispicula. It differs from other snake capillarids in its greater size, higher ratio of anterior to posterior body regions, larger eggs, and more elaborate male caudal bursalike expansion. This is the first capillarid reported from the oviducts of a vertebrate host. Several species of Capillaria have been reported from snakes in South and Middle America (Teixiera de Freitas and Lent, 1935; Aravjo and Gandra, 1943; Caballero and Cerecero, 1944; Yamaguti, 1961). However, Capillaria heterodontis Harwood, 1932, is apparently the only species described from a snake endemic to the United States. Between 1967 and 1969 17 specimens of Capillaria were removed from the oviducts of three southern black racers collected near New Orleans, Louisiana. These specimens represent a new species. Capillarids were removed from the oviducts, fixed in glacial acetic acid, stored in a mixture of alcohol, formalin, and glycerin, and studied in glycerin mounts after evaporation of the alcohol at room temperature. Drawings were made with the aid of a camera lucida. In the following description measurements are in millimeters unless otherwise noted. Capillaria colubra sp. n. (Figs. 1-6) Definition: Trichuridae Railliet, 1915; Capillariinae Railliet, 1915; Capillaria Zeder, 1800. Body diameter increasing from anterior to about the posterior three-fourths. Body very slender, threadlike. Cuticle smooth. Two lateral bacillary bands. Mouth small, porelike. Esophagus consisting of a single chain of stichocytes, some cells darker than others and containing granules, alternating with lighter cells devoid of granules. Anterior region shorter than posterior region of body in male and female. Female slightly longer than male. Received for publication 10 October 1969. * Supported in part by a Predoctoral Fellowship, 5-F01-GM-38,070, awarded by National Institute of General Medical Sciences, NIH, Public Health Service. Male (9 specimens): 19.56 to 26.40 (21.83) long, 68 to 78 /L (72) maximum width. Anterior region of body 5.54 to 6.90 (5.96) long, with muscular pharynx 304 to 552 /L (425) long, followed by 40 to 59 (45) stichocytes. Posterior egion of body 13.84 to 19.50 (15.88) long. Ratio of anterior to posterior region 1:2.4 to 1:2.9 (1:2.7). Ratio of anterior region to total length 1:3.4 to 1:3.9 (1:3.7). Posterior extremity bears ventrally a small bursalike expansion and 2 small papillae. Body terminates in short blunt tail dorsally. Cloaca 3.31 to 3.70 (3.45) in length. Anus subterminal, surrounded by bursa. Spicule 2.22 to 2.96 (2.59) long, 12 to 17 /u (14) at maximum width, transversely striated, with blunt tip. Spicule sheath long, transversely striated, 18 to 26 / (22) at maximum width. Female (8 specimens): 29.15 to 36.46 (31.99) long, 77 to 100 ,u (87) at maximum width. Anterior region of body with muscular pharynx 276 to 684 /, (490) long, followed by 40 to 52 (48) stichocytes. Posterior region 24.51 to 30.29 (25.71) long. Ratio of anterior to posterior regions 1:3.4 to 1:4.9 (1:4.1). Ratio of anterior to total length 1:4.4 to 1:5.9 (1:5.1). Vulva 100 to 150 A (130) posterior to last stichocyte, anterior and posterior lips slightly salient. Anus subterminal. Posterior extremity slightly rounded and blunt, caudal papillae absent. Eggs unembryonated, 61 to 70 / (65) in length, 28 to 31 ,/ (30) in width. Holotype male: USNM Helm. Coll. No. 70563. Allotype female: USNM Helm. Coll. No. 70564. Paratypes: USNM Helm. Coll. No. 70565. Host: Coluber constrictor priapus Dunn and Wood, 1939. Location: Posterior region of oviducts; anterior end threaded into the mucosa, posterior region free in the lumen. Locality: Covington, Louisiana, USA 30?30' N, 90010' W. DISCUSSION The capillarids of cold-blooded vertebrates were thoroughly reviewed by Teixiera de Freitas and Lent (1935). In addition, Yama-

Stability of towed, totally submerged flexible cylinders

A general theory is presented to account for the small, free, lateral motions of a flexible, slender, cylindrical body with tapered ends, totally submerged in liquid and towed at steady speedU. For particular shapes of the ends and length of tow-rope, it is shown that the body may be subject to oscillatory and non-oscillatory instabilities forU&gt; 0; at smallU, these instabilities correspond to those of a rigid body. At higherU, the system generally regains stability in the above modes, but may be subject to higher-mode, flexural oscillatory instabilities. The critical conditions of stability are calculated extensively and the effect on stability of a number of dimensionless parameters is discussed. It is shown that optimum stability is achieved with a streamlined nose, a blunt tail and a short tow-rope.Some experiments are described which were designed to test the theory. Rubber cylinders of neutral buoyancy were held in vertical water flow by a nylon ‘tow-rope’. Provided the tail was streamlined and the tow-rope not too short, ‘criss-crossing’, non-flexural oscillations developed at very low flow. Increasing the flow, these oscillations ceased and the cylinder buckled like a column; subsequently higher-mode flexural oscillations developed. However, for a sufficiently blunt tail and short tow-rope, the system was completely stable.The experimental observations are generally in qualitative agreement with theory. Quantitative comparison of the various instability thresholds and stable zones between experiment and theory, based on estimated values of some of the theoretical dimensionless parameters, is also fairly good.