Pair Of Ridges Research Articles

Evaluation of Plants Extracts from Capsicum annum and Allium sativum against Aphis craccivora Attacking Cowpea Plant in Kano, Nigeria

The efficacy of Capsicum annum fruits and Allium sativum cloves methanolic crude extracts were evaluated on field for the control of Aphis craccivora attacking cowpea plants. Two cowpea genotypes (IAR-48 and IT97K-499-35) were planted separately in a randomized block design, for a cowpea genotype an experimental plots measured 5m x 3m with 1.5m space between plots was demarcated. The plot contained four subplots each measured 1.67m x 3m and replicated three times, given the total of twelve subplots. Within a subplot are three pairs of ridges (70cm apart) tallied with the three different concentrations (200, 600 and 1000ppm) for the plant extracts treatments application. Plant extract treatments along side with synthetic chemical insecticide (Magic force) as positive control were applied to the subplots using Knapsack sprayer 15 days after sowing. The results showed that the population scores of A. craccivora after treatments application on susceptible genotype IAR-48 was reduced significantly (p <0.05) when compared with untreated control subplot. The least population scores of this insect on genotype IAR-48 was recorded in plants treated with A. sativum at 600ppm concentration level which was effective over positive control (synthetic chemical). The genotype IT97K-499-35 recorded no population aphid in plants treated with A. sativum at 200ppm concentration level which is also effective over the positive control. There is critical need to enhance the use of plant extracts scientifically on field as part of Integrated Pests Management for safe food production.

On the geomagnetic secular variation in the Pacific region

It is widely believed that in the Pacific region the geomagnetic secular variation is low and that the non-dipole field is weak. This is also known as hemispherical asymmetry between the Pacific and the Atlantic hemispheres, representing the low secular variation in the Pacific hemisphere. With this characteristic feature, a question has been left unsolved whether it is a permanent feature or a transient one.Reexamination of the geomagnetic field for the past 400 years indicates that in the early 17th century the non-dipole field was not weak, nor the secular variation was low in the Pacific region, implying that the hemispherical asymmetry is not a permanent phenomenon. This paper examines the secular variation for the past 400 years from viewpoint of drifting and standing field model. It has been found that the low secular variation in the Pacific region is mainly caused by the drift of the drifting field. At the Earth’s surface the drifting field is dominated by spherical harmonics Y22(θ,ϕ) with two pairs of ridges and troughs with their axes aligned in the meridional direction. The two pairs are not equal; one pair is stronger than the other. Movements of the different magnitude of the pairs are considered to have caused the hemispherical asymmetry of the secular variation for recent years, giving rise to the non-weak field in the Pacific region in the early 17th century.

Fabrication of optical gratings through surface patterning of zirconium-based metallic glass by laser irradiation

Periodic lines with intervals ranging from ∼220 μm down to ∼27 μm were fabricated on the surface of Zr55Cu30Al10Ni5 metallic glass ribbon and disk samples by laser irradiation. The X-ray diffraction results indicated that both oxides (monoclinic ZrO2, tetragonal ZrO2) and crystallites (Cu10Zr7, NiZr2) existed together with the amorphous phase on the surface of the laser-patterned metallic glass samples. The energy-dispersive X-ray spectroscopy of a cross section of a disk sample clearly showed that high amounts of aluminum (292% of the nominal composition) and oxygen were present in the laser-irradiated area, suggesting that Al2O3 formed on the surface of the laser-irradiated region. Reflective diffraction spots were observed from the fine grids with a grating period of ∼27 μm, indicating the excellent periodicity and accuracy of the pattern in two dimensions on the surface of the metallic glass substrates. Calculation of the grating period using Bragg's law confirmed that the spots originated from the periodic patterns of the laser-irradiated lines. Along the lines, pairs of ridges and hollows with a height/depth of ∼0.5 μm were observed; such specific morphology generated the diffraction spots as a reflective grating. We observed structural color gradation from the periodic fine grids under a fluorescent light. The present study showed that it is possible to prepare optical gratings on the surface of metallic glasses by laser irradiation more cheaply and easily than by conventional imprinting.

A new edentulous pterosaur from the Cretaceous Kem Kem beds of south eastern Morocco

A new genus and species, Xericeps curvirostris gen. et sp. nov., is erected for a highly distinctive pterosaur mandible from the mid-Cretaceous (?Albian to lower Cenomanian) Kem Kem beds of south east Morocco. The new taxon is referred to Azhdarchoidea based on the absence of teeth, slenderness of its mandible with sulcate occlusal surface, presence on the posterior section of the mandibular symphysis of short paired ridges bounding a central groove, and the presence of elongate foramina on its occlusal and lateral surfaces. A slight dorsal curvature determines it as a distinct genus of azhdarchoid, as does an autapomorphy: the presence of a continuous longitudinal groove on the ventral midline of the mandibular symphysis. The new species brings to three the number of named pterosaurs from the Kem Kem beds and together with an unnamed tapejarid, points to a relatively diverse pterosaur assemblage in these deposits.

Relationships of the Indian phytosaur Parasuchus hislopi Lydekker, 1885

AbstractThe neotype skull of the Indian phytosaur Parasuchus hislopi Lydekker, 1885 (ISI R42) is re‐evaluated and compared with the type material of other basal phytosaurs. Parasuchus hislopi is extremely similar to species previously placed in Paleorhinus (P. bransoni and P. angustifrons), sharing with them such characters as a series of nodes on the lateral surface of the jugal, paired ridges on the squamosal and a frontal depression. Parasuchus hislopi represents a valid species: it can be distinguished from P. bransoni by a relatively low narial eminence and P. angustifrons by the absence of paired nasal depressions. Inclusion of Parasuchus hislopi in a phylogenetic analysis of phytosaurs recovers it in a well‐supported clade with P. bransoni and P. angustifrons. Parasuchus is considered the senior synonym of Paleorhinus and Arganarhinus. Parasuchus (here considered to include P. hislopi, P. angustifrons, P. bransoni and P. magnoculus) has a broad circum‐Pangaean distribution, with species occurring in the south‐western United States, Morocco, central Europe and India. Phytosaur higher‐level taxonomy is also revised: Parasuchidae is redefined to include ‘Paleorhinus‐grade’ phytosaurs and the later‐diverging Mystriosuchinae (the group formerly known as Phytosauridae), and Pseudopalatinae is renamed Mystriosuchini for reason of priority.

An ameghinornithid-like bird (Aves, Cariamae, ?Ameghinornithidae) from the early Oligocene of Egypt

The Ameghinornithidae are an enigmatic group of potentially flightless Paleogene birds currently known from three European species. Herein, we report a new fossil that represents the first record of an ameghinornithid-like bird from Africa. The new specimen was collected from the early Oligocene Jebel Qatrani Formation exposed in the Fayum Depression of northern Egypt, and may represent the youngest record of the clade. The new specimen exhibits many similarities with European ameghinornithids, including the absence of an ossified supratendinal bridge on the tibiotarsus, a circular lateral condyle of the tibiotarsus, and a large medial epicondyle. The Fayum specimen is intermediate in size compared to the European ameghinornithids and is characterized by the absence of a projection of the medial condyle cranial to the lateral condyle and the presence of paired ridges (and associated grooves) proximal to the lateral condyle. The occurrence of Ameghinornithidae in the early Oligocene of Africa would have implications regarding the timing and pattern of biogeographic interchanges across the Tethys seaway. Thomas A. Stidham. Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China. presbyornis@gmail.com N. Adam Smith. National Evolutionary Synthesis Center, 2024 West Main Street, Suite A200, Durham, North Carolina 27705 U.S.A.; North Carolina Museum of Natural Sciences, 11 West Jones Street, Raleigh, North Carolina 27601 U.S.A. adam_smith@utexas.edu

Experimental investigation of double-groove grating satisfying total internal reflection condition.

We experimentally demonstrate a TiO(2) double-groove grating coupler with two different groove widths on a SiO(2) substrate in the visible region. Tolerance investigations based on Bloch-mode profiles in the grating and coupling strengths between the Bloch modes and diffraction orders reveal that the transmission performance is robust when one of the paired ridges is narrow enough (60 nm and less) considering a typical nanofabrication accuracy. Moreover, the ridge shape affects weakly the transmission performance due to the non-resonance operation of our dielectric device. Such tolerance investigations together with current nanofabrication technology enable us to accomplish a 70% efficiency for coupling the normal incident light into the + 1st order transmission diffraction satisfying the total internal reflection condition at a 640 nm wavelength of operation.

Redescription of the phytosaursPaleorhinus(‘Francosuchus’)angustifronsandEbrachosuchus neukamifrom Germany, with implications for Late Triassic biochronology

Phytosaurs are a diverse and morphologically distinctive clade of superficially crocodile-like archosauriforms that had a near global distribution during the Late Triassic. Because their remains are among the most abundant vertebrate remains recovered in many Upper Triassic terrestrial formations, phytosaurs are used extensively in long-range biochronological and biostratigraphic correlations. The biochronologically oldest and earliest branching known phytosaurs include an array of nominal species from the early Late Triassic of the United States, Germany, Poland, Morocco, and India that have been synonymized within the genus Paleorhinus, and subsequently used to define a global ‘Paleorhinus biochron’. However, recent phylogenetic work suggested that the North American species previously referred to Paleorhinus are paraphyletic. Here, we reassess the systematics and anatomy of putative specimens of Paleorhinus from southern Germany. Two well-preserved basal phytosaur skulls from the Blasensandstein (Carnian) of Bavaria form the holotypes of Francosuchus angustifrons and Ebrachosuchus neukami, both of which were synonymized with Paleorhinus by previous workers. We demonstrate that Francosuchus angustifrons shares unique synapomorphies with specimens referred to Paleorhinus bransoni from the Late Triassic of Texas, and thus refer the species to Paleorhinus. By contrast, the longirostrine Ebrachosuchus is highly distinctive in morphology, and our new cladistic analysis of Phytosauria demonstrates that it represents a valid taxon that is more closely related to Phytosauridae than to Paleorhinus. We provide the first autapomorphy-based support for a monophyletic but restricted Paleorhinus (supported by a nodal row on the jugal, and low paired ridges on the squamosal) and confirm that previous broader conceptions of Paleorhinus are likely to be paraphyletic. © 2013 The Linnean Society of London

Differential Fabry–Perot Resonator Antennas

The differential Fabry-Perot resonator (FPR) antenna is investigated for the first time. It has advantages of suppressing the cross polarization and enabling integration with differential circuits. Its basic structure consists of two vertical parallel metal plates, which are connected by a horizontal ground plane. The differential FPR antenna is fed by a pair of differential L-probes protruding from the ground plane. It is found that the basic differential FPR antenna has considerable sidelobes in the E-plane. To suppress the sidelobes, a modified differential FPR antenna is proposed which has a pair of ridges at each side-opening of the parallel plates. In addition, a second modified differential FPR antenna is also proposed to reduce undesirable backward radiation. The second modified antenna has a pair of ridges placed at the top of each metal plate. It is found that all of the basic and modified antennas have low cross polarizations. The two modified differential FPR antennas were fabricated and measured, and the measurements agree reasonably well with HFSS simulations. The first and second modified antennas have calibrated measured gains of 14.2 dBi and 15.4 dBi, respectively, with measured 10-dB impedance bandwidths of ~ 2.4%.

3D Flow in the Venom Channel of a Spitting Cobra: Do the Ridges in the Fangs Act as Fluid Guide Vanes?

The spitting cobra Naja pallida can eject its venom towards an offender from a distance of up to two meters. The aim of this study was to understand the mechanisms responsible for the relatively large distance covered by the venom jet although the venom channel is only of micro-scale. Therefore, we analysed factors that influence secondary flow and pressure drop in the venom channel, which include the physical-chemical properties of venom liquid and the morphology of the venom channel. The cobra venom showed shear-reducing properties and the venom channel had paired ridges that span from the last third of the channel to its distal end, terminating laterally and in close proximity to the discharge orifice. To analyze the functional significance of these ridges we generated a numerical and an experimental model of the venom channel. Computational fluid dynamics (CFD) and Particle-Image Velocimetry (PIV) revealed that the paired interior ridges shape the flow structure upstream of the sharp 90° bend at the distal end. The occurrence of secondary flow structures resembling Dean-type vortical structures in the venom channel can be observed, which induce additional pressure loss. Comparing a venom channel featuring ridges with an identical channel featuring no ridges, one can observe a reduction of pressure loss of about 30%. Therefore it is concluded that the function of the ridges is similar to guide vanes used by engineers to reduce pressure loss in curved flow channels.

A new aetosaur from the Upper Triassic Chinle Formation of the Eagle Basin, Colorado, USA

Abstract A small aetosaur skull and skeleton and referred material from the Chinle Formation, Eagle Basin of Colorado, USA, is described as a new taxon, Stenomyti huangae gen. et sp. nov, distinguished from other aetosaurs by the following autapomorphies: three premaxillary teeth; four palpebrals; pronounced midline ridge on frontals and parietals; paired ridges flanking midline ridge on parietal and frontal; exclusion of quadratojugal from ventral margin of skull by contact between jugal and quadrate; exclusion of postorbital from infratemporal fenestra; infratemporal fenestra a horizontally oriented oval that embays the posterior edge of the jugal; retroarticular process longer than distance between articular glenoid and posterior edge of external mandibular fenestra; oval to irregularly shaped ventral osteoderms that do not contact each other. Paramedian and lateral osteoderms of S . huangae are nearly identical to those of Aetosaurus ferratus , and other shared cranial characters suggest that these taxa are closely related and lie outside the clade Typothoracisinae + Desmatosuchinae. This discovery indicates that other reports of Aetosaurus across Laurasia based on osteoderms should be reassessed. Similar confusion with the osteoderms of other non-typothoracisine/desmatosuchine aetosaurs such as Aetosauroides , Stagonolepis and Calyptosuchus suggests that osteoderms are not always reliable taxonomic indicators.

Micro-relief development in polygonal patterned ground in the Dry Valleys of Antarctica

Polygonal patterned ground in polar regions of both Earth and Mars has received considerable attention. In comparison with the size, shape, and arrangement of the polygons, the diverse micro-relief and topography (termed here simply “relief”) of polygonal patterned ground have been understudied. And yet, the relief reflects important conditions and processes occurring directly below the ground surface, and it can be observed readily in the field and through remote sensing. Herein, we describe the relief characteristic of the simplest and relatively young form of patterned ground in the Dry Valleys of Antarctic. We also develop a numerical model to examine the generation of relief due to subsurface material being shouldered aside contraction cracks by incremental sand wedges growth, and to down-slope creep of loose granular material on the surface. We model the longterm subsurface deformation of ice-cemented permafrost as a non-linear viscous material. Our modeling is guided and validated using decades of field measurements of surface displacements of the permafrost and relief. This work has implications for assessing the activity of surfaces on Earth and Mars, and much larger scale potential manifestations of incremental wedging in icy material, namely the distinct paired ridges on Europa.

Uniqueness of the palatine rugae (ridges) - morphological analysis

The transverse palatine rugae (PR) are asymmetrical and irregular folds of the anterior one third of the palatine mucosa. The PR were considered relevant for the human identification, due to their stability, similar to the fingerprints; their study is identified as palatoscopy. The aim of this study is to describe the shape and the biometrical characteristics of the palatine ridges. We evaluated 72 adult subjects, of which 64 were dentate and 8 edentate. Each patient was imprinted at the level of the upper jaw. Each cast was analyzed in terms of total number of ridges, number of primary, secondary and fragmented ridges, shape, unification and direction. In terms of total number of ridges, the smallest number of ridges was 6, and the largest 18. A feature of the dentate group was the asymmetry of the ridges, only 12 showed paired ridges. Among the non-dentate group we noticed that the total number of ridges is higher in females than in males. The length of the palatine ridges is mainly of a primary type, followed by the secondary type and the fragmentary one. What differentiates the sexes in this case is the number of fragmentate ridges, predominant within female patients. Concerning the shape of the palatine rugae, we noticed, among all the age groups that the linear ridges are predominant, followed by the wavy, curved, angular, punctiform and circular type. Regarding the orientation and the unification of the ridges, we noticed similarities between males and females. The only aspect that may differentiate them is the variety of shapes and their number, which gives them individuality. The palatine rugae are paired only in a small proportion in our study, 19% versus 81%. The length is mainly primary type, regardless of sex, age or degree of edentation. The large number of fragmented ridges is typical to females. The individuality of each ridge drawing is certain as long as we did not encounter identical models.

Even and odd mode cut-off parameters of pairs of ridges in rectangular waveguide using a mode matching solver

A waveguide geometry of some interest consists of a symmetrical pair of ridges in a rectangular waveguide. The paper gives the even and odd mode cut-off spaces of such a structure in addition to its corresponding standing wave patterns. The classic power-voltage, power-current and voltage-current definitions of impedance of the two solutions are also evaluated. The calculations are based on a mode matching procedure and are verified separately using a finite element solver. A knowledge of these parameters is sufficient for the design of a proximity, reverse, directional coupler.

Perforation Plate Pit Membrane Remnants and Other Vessel Details of Clethraceae: Primitive Features in Wood of Ericales

Wood of 12 species of Clethra was studied with SEM; wood features are illustrated here for eight of these. Pit membrane remnants were observed in perforations of all species, although in some, the remnants occur only in the form of small webs at the lateral ends of perforations. Pit membranes take the form of threads or porose sheets; the former are more common. Extensive pit membrane remnants are uncommon in tropical species and are more characteristic of temperate species, perhaps because of water flow characteristics. As with other dicotyledons, occurrence of pit membrane remnants in perforations is considered a primitive feature in Clethraceae. Pit membrane remnants also occur in families of Ericales placed in primitive positions in the order and close to Clethraceae: Cyrillaceae and Sarraceniaceae. Bars of perforation plates are numerous and are prominently bordered. Grooves interconnecting pit apertures occur in distal portions of vessel elements and are accompanied by pairs of ridges in some specie...

Experiments of autoresonant peniotron using a parallel transmission line with double pairs of ridges

A parallel transmission line with double pairs of ridges was proposed and fabricated to support the autoresonant peniotron at the second cyclotron harmonic. A test circuit was designed to yield an efficiency of 57% in the second harmonic n = 16 mode. Experiments using this design demonstrated transverse electromagnetic mode excitation by the autoresonant peniotron interaction in the n = 17 mode at 21.4 GHz, albeit with an efficiency (6.8%) significantly lower than predicted by the simulation. Future experiments for improving the efficiency are discussed.

Canine ocular onchocercosis in Hungary

An adult male mongrel dog that had spent its entire life in Hungary, was found to have infection with filaroid nematodes of the genus Onchocerca. The gravid male and female parasites were embedded in bean-sized granulomatous masses on the conjunctiva and the sclera of both eyes. The cuticle of females consisted of two separated layers in longitudinal sections, the external layer bearing ridges and the internal layer showing striations. The ridges were marked, rounded in shape, and the ratio of body diameter to the distance between ridges varied between 7:1 and 10:1. At midbody of the worms, two striations could be seen between each pair of ridges: one under every ridge and one between neighbouring ridges. Numerous exceptionally small ( 96.4 μm×6.4 μm) microfilariae were seen in the uteri of females and the surrounding tissues and isolated from skin biopsy materials. The morphology and location of the parasite and histopathological lesions of the Hungarian case were similar to that described in dogs in the United States. This case is the first documented ocular Onchocerca infection in dogs outside the western United States. Thus, onchocercosis should be considered in the differential diagnosis of ocular and periocular nodules in dogs also in Europe.

Ridge belts on Venus: Morphology and origin

Ridge belts, composed of closely spaced individual ridges 5–20 km wide, form sinuous patterns 30–400 km wide and 200–2000 km long in the plains of northern Venus. They are not homogeneously distributed, but occur primarily in two regions: between 0 ° E and 90 ° E ridge belts are associated with large blocks of tessera, and have a cumulative length of about 13,200 km; and between 150 ° E and 250 ° E, the ridge belts form a fan-shaped pattern and have a total cumulative length of about 25,800 km. Most ridge belts trend within 10 ° of N-S. Five morphologic components exist within the ridge belts: (1) broad ridges, which have no sharp crest and usually occur individually in the plains: (2) discontinuous ridges, with short ridge segments less than 20 km long; (3) paired ridges, with closely spaced ridges (less than 10 km apart) that never merge; (4) parallel ridges, with widely spaced (10–50 km), less prominent ridges; and (5) anastomosing ridges, in which ridges splay at angles up to 30 °. Subtle cross-strike lineaments cut the ridge belts at angles of 30–90 ° to the ridge belt, and augen-shaped plains are often present in anastomosing ridges. We examine the relationships between the components, plains, cross-strike lineaments, and augen-shaped plains in five ridge belts. Broad arches similar to the arches associated with wrinkle ridges on the Moon, Mars and Mercury appear in all of the ridge belts examined. Through studying each of these components individually and in the context of five specific ridge belts, we conclude that these ridge belts formed by compressional forces. The ridge belts form a continuum of deformation, from the simple broad arches (Nephele Dorsa), representing small amounts of shortening, through asymmetric ridge belts in the plains (Pandrosa Dorsa) and adjacent to tessera (Kamari Dorsa), to ridge belts in troughs representing underthrusting (Ausra and Lukelong Dorsa). Underthrusting is also observed along the borders of Lakshmi Planum, associated with Freyja and Danu Montes.

Angiographic features in the infarct-related artery after intracoronary urokinase followed by prolonged anticoagulation. Role of ruptured atheromatous plaque and adherent thrombus in acute myocardial infarction in vivo.

To unravel sequential morphological features in infarct-related coronary arteries (IRCA), we performed coronary angiography (CAG) before, during, and immediately after intracoronary urokinase infusion in 43 consecutive patients. After 1 month of rigorous anticoagulation by intravenous heparin and subsequent oral warfarin or after the same period of treatment by antiplatelet agents, we repeated CAG in all patients except for one, who died 6 days after thrombolytic therapy. Thirty-two IRCAs were totally occluded, and 11 were severely occluded at baseline. With recanalization and/or reduction in luminal narrowing at the site of the occlusion by progressive removal of the overlying thrombus and plaque content, we recognized the development of extraluminal contrast pooling in an ellipsoid shape (type A), single or paired linear radiolucency(ies) with or without outpouching (type B), and definite outpouching (type C). The development of type A, B, and C lesions occurred in 4, 6, and 0 IRCAs immediately after thrombolytic therapy and in 0, 18, and 3 IRCAs 1 month later, respectively. Throughout the study, at least one of type A-C lesions developed in 23 of 43 (53.5%) IRCAs. Lesion development proceeded from total or severe occlusion to type A, then to type B or C, both accompanied by progressive reduction in luminal narrowing and frequent enlargement of outpouching. A postmortem study in one patient whose CAG immediately after thrombolytic therapy was interpreted as a type B lesion demonstrated a ruptured plaque with paired ridges. Serial observations in vivo indicate that many IRCAs are associated with a complex underlying spatial structure, probably composed of some part of ruptured atheromatous plaque with or without adherent thrombus. Recognition and identification of such complex structures beneath the accumulated thrombus are of great importance in both CAG interpretation and elucidation of the pathophysiological sequence of acute myocardial infarction in vivo and may enable prevention or more effective therapy of acute coronary events.

Flow visualization experiments on stably stratified flow over ridges and valleys

Flow visualization experiments on stably stratified flow over ridges and valleys formed by a pair of ridges were conducted in a large towing tank filled with stratified salt water. The ambient flow was normal to the axis of the ridges. Three experimental parameters were varied during the study: the steepness of the ridges, the separation distance between the ridges and the Froude number. The flow field in the valley was strongly influenced by flow separation from the lee side of the upstream ridge. For the gentle and intermediate ridges with maximum slopes of 13° and 27°, this separation was controlled by the lee waves when their wavelength was less than or equal to the width of the ridge. The flow field in the valley was similar to that downstream of a single ridge. For the steep ridge with a maximum slope of 40°, separation from the lee side of the upstream ridge and the flow field in the valley were influenced significantly by the presence of the downstream ridge.