Prominent Cusp Research Articles

Prevalence of Cusp of Carabelli in Upper First Molars in Salahdin Governate and Its Caries Susptability

This study was performed to measure distribution of different types of Carabelli cusps among population and relationship of each cusp type with dental caries. Method: this study included the examination of 200 patients for both right and left sides, to find the distribution of Carabelli cusp and their caries susptability. Patients with severe destructed or extracted upper first molar from any side were excluded. Results: percentage of presence or appearance of prominent Carabelli cusp was approximately 23%. Groove obtained in 33% of total examined teeth. Prominent cusps showed higher rate of caries infection, while smooth surface had lower caries susptability. Conclusion: according to the anatomical differences of mesiopalatal surface of upper first molar, Carabelli cusp prevalence was high and caries susptability was increased in positive cusp expression

A functional analysis of Carabelli trait in Australian aboriginal dentition.

Carabelli is a nonmetric dental trait variably expressed as a small pit to a prominent cusp in the maxillary molars of modern humans. Investigations on the occurrence and expression rates of this trait have been conducted extensively, tracing its origin to genetic sources. However, there remains a lack of understanding about its potential role in chewing. In this study, we examine molar macrowear with the aim of reconstructing Carabelli trait occlusal dynamics occurring during chewing. We have examined 96 deciduous and permanent maxillary molars of children and young adults from Yuendumu, an Australian Aboriginal population that was at an early stage of transition from a nomadic and hunter-gatherer way of life to a more settled existence. We apply a well-established method, called Occlusal Fingerprint Analysis, which is a digital approach for analyzing dental macrowear allowing the reconstruction of jaw movements required to produce wear pattern specific to each tooth. Carabelli trait slightly enlarges the surface functional area, especially in those molars where this feature is expressed in its cuspal form and it is closer to the occlusal plane. Moreover, the highly steep contact planes would also indicate that Carabelli wear areas contribute to increasing the shearing abilities of the occluded teeth, which are particularly important when processing fibrous and tough foods. The macrowear analysis suggests that Carabelli trait in the Aboriginal people from Yuendumu slightly enhanced occlusion and probably played some functional role during mastication. Future biomechanical and microwear analyses could provide additional information on the mechanical adaptation of Carabelli trait in modern human dentition.

A late Paleocene probable metatherian (?deltatheroidan) survivor of the Cretaceous mass extinction.

Deltatheroidans are primitive metatherian mammals (relatives of marsupials), previously thought to have become extinct during the Cretaceous mass extinction. Here, we report a tiny new deltatheroidan mammal (Gurbanodelta kara gen. et sp. nov.) discovered at the South Gobi locality in China (Xinjiang Province) that is the first Cenozoic record of this clade and renders Deltatheroida a Lazarus taxon (with a new record 10 million years younger than their supposed extinction). The vertebrate fauna associated with Gurbanodelta is most similar to that from the slightly older late Paleocene Subeng locality in Inner Mongolia. The upper molars of Gurbanodelta exhibit a broad stylar shelf with one prominent cusp (stylocone), and a paracone that is sharp and significantly taller than the metacone. The lower molar tentatively assigned to Gurbanodelta has a very small talonid without an entoconid. This combination of these features is known only in deltatheroidans. Phylogenetic analysis places Gurbanodelta as the sister taxon of the North American latest Cretaceous Nanocuris. Gurbanodelta is the smallest-known deltatheroidan, and roughly the same size as the smallest living marsupial. It is likely that the Gurbanodelta lineage dispersed between Asia and North America as part of known intercontinental mammalian dispersals in the late Paleocene, or possibly earlier.

Emergence of an Out-of-Plane Optical Phonon (ZO) Kohn Anomaly in Quasifreestanding Epitaxial Graphene

In neutral graphene, two prominent cusps known as Kohn anomalies are found in the phonon dispersion of the highest optical phonon at q=Γ (LO branch) and q=K (TO branch), reflecting a significant electron-phonon coupling (EPC) to undoped Dirac electrons. In this work, high-resolution electron energy loss spectroscopy is used to measure the phonon dispersion around the Γ point in quasifreestanding graphene epitaxially grown on Pt(111). The Kohn anomaly for the LO phonon is observed at finite momentum q~2k_{F} from Γ, with a shape in excellent agreement with the theory and consistent with known values of the EPC and the Fermi level. More strikingly, we also observe a Kohn anomaly at the same momentum for the out-of-plane optical phonon (ZO) branch. This observation is the first direct evidence of the coupling of the ZO mode with Dirac electrons, which is forbidden for freestanding graphene but becomes allowed in the presence of a substrate. Moreover, we estimate the EPC to be even greater than that of the LO mode, making graphene on Pt(111) an optimal system to explore the effects of this new coupling in the electronic properties.

On the mechanical properties of tooth enamel under spherical indentation

The mechanical properties of tooth enamel generally exhibit large variations, which reflect its structural and material complexity. Some key properties were evaluated under localized contact, simulating actual functioning conditions. Prominent cusps of extracted human molar teeth were polished down ∼0.7mm below the cusp tip and indented by tungsten carbide balls. The internal damage was assessed after unloading from longitudinal or transverse sections. The ultimate tensile stress (UTS) was determined using a novel bilayer specimen. The damage is characterized by penny-like radial cracks driven by hoop stresses and cylindrical cracks driven along protein-rich interrod materials by shear stresses. Shallow cone cracks typical of homogeneous materials which may cause rapid tooth wear under repeat contact are thus avoided. The mean stress vs. indentation strain curve is highly nonlinear, attributable to plastic shearing of protein between and within enamel rods. This curve is also affected by damage, especially radial cracks, the onset of which depends on ball radius. Several material properties were extracted from the tests, including shear strain at the onset of ring cracks γF (=0.14), UTS (=119MPa), toughness KC (=0.94MPam1/2), a crack propagation law and a constitutive response determined by trial and error with the aid of a finite-element analysis. These quantities, which are only slightly sensitive to anatomical location within the enamel region tested, facilitate a quantitative assessment of crown failure. Causes for variations in published UTS and KC values are discussed.

Morphological alterations in the dentition of type I diabetes mellitus patients.

Introduction:Type 1 diabetes mellitus (DM) is an endocrine disorder that occurs commonly in an age group, where the development of primary and permanent dentition takes place. As altered endocrine functions may affect the shape and size of teeth leading to dental anomalies, this study was conducted to look for the occurrence of any dental anomalies in type I DM patients.Materials and Methods:A diabetic camp was conducted at Alur Chandrashekharappa Memorial Hospital, Davangere, where 30 diabetic patients were examined and the impressions of their maxillary and mandibular arches were recorded. Age and sex matched controls were selected randomly, and similar recordings were done.Results:Type I diabetic patients showed statistically significant (P < 0.001) morphological alterations of total number of cusps, including presence of 6th cusp in mandibular molars and extra cusps in mandibular premolars. Other alterations such as microdontia, flower shaped mandibular molars, prominent cusp of carabelli, and oblique ridge in maxillary molars were also noted. Severe attrition was found in 11 (36.6%) of the diabetic patients, whereas the control group showed attrition only in 2 (6.8%) patients.Conclusion:Remarkable morphological alterations do occur in the dentition of type I DM patients.

Dia-Magnetic to Ferro-Magnetic Behavioral Change of Fe-Catalysts Based Nitrogenated Carbon Nanotubes (NCNTs) by the Process of Chlorination/Oxidation

In this work, we have synthesized multiwall nitrogenated carbon nanotubes (MW-NCNTs) with Fe-catalysts by the microwave plasma-enhanced chemical vapor deposition process @950 degrees C and subsequently functionalized with chlorine and oxygen. The dia-magnetic behavioral M-H loop of non-functionalized MW-NCNTs were turn into ferromagnetic behaviors by the process of chlorination and oxidation respectively; which were characterized by means of superconducting quantum interference device magnetometer within the temperature range 5-300 K. A prominent cusp like behavior is also observed at around approximately 45 K in M(FC) and M(ZFC) measurements confirming the ferromagnetic behaviors of these MW-NCNTs after chlorination and oxidation.

Anisotropic edge retraction and hole growth during solid-state dewetting of single crystal nickel thin films

At elevated temperatures, single crystal thin films sometimes undergo solid-state dewetting to form holes and islands with anisotropic morphologies and regular features. We have measured the rates of edge retraction for single crystal Ni(1 0 0) and Ni(1 1 0) films with edges patterned along different in-plane crystallographic directions. The polar plots of the edge retraction velocities have anisotropic shapes with prominent cusps in particular directions. The characteristic anisotropy in the edge retraction velocity can be understood in terms of in-plane orientation-dependent edge faceting, with single faceting of specific edges and multiple micro-faceting in other edges. Faceting occurs due to surface energy minimization, and is modified by changes in the annealing ambient. Changes in facet morphologies affect the relative edge retraction rates in different crystallographic orientations and also the initial shapes of holes growing in the film. The mechanistic understanding of edge retraction provided through these studies will provide a basis for understanding the evolution of complex morphologies that result from solid-state dewetting of unpatterned single crystal films.

A rare Danian (early Paleocene) Chlamydoselachus (Chondrichthyes: Elasmobranchii) from the Takatika Grit, Chatham Islands, New Zealand

ABSTRACT Chlamydoselachus teeth recorded from the Takatika Grit, Chatham Islands, Southwest Pacific, are Danian in age and represent a new species of Chlamydoselachidae and the oldest Cenozoic record in the world, once considered to be Lazarus taxon for the early Paleogene. The new species Chlamydoselachus tatere n. sp. is diagnosed by three prominent upright cusps that display weak ornamentation restricted to the base of the cusp, a cutting edge that reaches the root and lacks intermediate cusplets. The root is broader than long and is labiolingually shortened with a wide transverse notch and poorly differentiated lobes. The variable tooth morphology within these Chatham specimens confirms that the fossil taxon has a slight degree of intraspecific variation laterally within dentition. Posterolaterally, the cusps become more gracile with greater lingual inclination and increasing separation between cusps. Also, the root becomes labiolingually shorter and the transverse notch wider and shallower. The presence of the chlamydoselachians in the shallow marine Takatika Grit indicates that early in its evolutionary history the group may have inhabited shallow neritic environments and their teeth were more robust, possibly a reflection of the sharks predatory lifestyle.

On a new Ercolania Trinchese, 1872 (Opisthobranchia, Sacoglossa, Limapontiidae) living within Boergesenia Feldmann, 1950 (Cladophorales), with notes on anatomy, histology and biology

A new sacoglossan species, belonging to the genus Ercolania Trinchese, 1872 is described. E. kencolesi sp. nov. has a similar biology as E. endophytophaga Jensen, 1999. Both are living within syncytial algal tubes of members of the Siphonocladales, E. kencolesi sp. nov. in Boergesenia forbesii and E. endophytophaga in Struvea plumosa. Assignment to the genus Ercolania is possible on the base of the cerata, which are round in cross-section, the digitiform rhinophores, sabot-shaped teeth and the presence of a penial stylet. The new species can be easily distinguished from E. endophyto-phaga, by the teeth with a prominent cusp, as well as other Ercolania species, by its unique colouration and its peculiar association to the food alga Boergesenia. Feeding, copulation, egg masses and development are noted. Differences in development further strengthen the distinction of E. kencolesi to E. endophytophaga. Measurement of photosynthetic activity of incorporated chloroplasts during several days clearly shows that chloroplasts are digested.

PS-wave moveout inversion for tilted TI media: A physical-modeling study

Mode-converted PS-waves can provide critically important information for velocity analysis in transversely isotropic (TI) media. We demonstrate, with physical-modeling data, that the combination of long-spread reflection traveltimes of PP- and PS-waves can be inverted for the parameters of a horizontal TI layer with a tilted symmetry axis. The 2D multicomponent reflection data are acquired over a phenolic sample manufactured to simulate the effective medium formed by steeply dipping fracture sets or shale layers.The reflection moveout of PS-waves in this model is asymmetric with respect to the source and receiver positions, and the moveout-asymmetry attributes play a crucial role in constraining the TI parameters. Applying the modified [Formula: see text] method to the PP and PS traveltimes recorded in the symmetry-axis plane, we compute the time and offset asymmetry attributes of the PS-waves along with the traveltimes of the pure SS reflections. The algorithm of Dewangan and Tsvankin is then used to invert the combination of the moveout attributes of PP-, SS-, and PS-waves for the medium parameters and the thickness of the sample. It should be emphasized that the pure-mode (PP and SS) traveltimes alone are insufficient for the inversion, even if 3D wide-azimuth data are available.Our estimates of the symmetry axis tilt and layer thickness almost coincide with the actual values. The inverted model is also validated by reproducing the results of transmission experiments with both P- and S-wave sources. The transmitted SV wavefield exhibits a prominent cusp (triplication) accurately predicted by the parameter-estimation results.

Study of the magnetic behavior of single-crystalline Nd0.5Sr0.5MnO3

Zero-field-cooled and field-cooled magnetization data in single-crystalline Nd0.5Sr0.5MnO3 revealed the existence of thermodynamic irreversibility below Curie temperature (TC), indicating the presence of frustration of spins. The imaginary part of ac susceptibility (χ″) indicates a prominent cusp below TC, which shifts to higher temperatures with increasing frequency. Magnetization, ac susceptibility, resistivity, and specific-heat measurements were used to find three critical exponents α=0.12(1), β=0.5(0), and γ=1.02(2). The values of the critical exponents are all between mean-field values and three-dimensional Heisenberg model values.

Earliest mammal with transversely expanded upper molar from the Late Triassic (Carnian) Tiki Formation, South Rewa Gondwana Basin, India

ABSTRACT A mammalian upper molariform tooth recovered from the Late Triassic (Carnian) Tiki Formation of the South Rewa Gondwana Basin, India, is described as a new taxon, Tikitherium copei, gen. et sp. nov. Coming from such an ancient horizon, the tooth is remarkable in having on its crown, which is supported by three roots, three buccally placed cusps forming an obtuse triangle, another prominent cusp with two associated shearing crests in the posterolingual corner, and a talon-like depression anterior to the latter. The molar with its several derived features, though showing partial similarity with those of some seemingly allied early mammalian dentitions, stands apart as a distinctly different entity in detailed comparison. Through close examination of the Tikitherium upper molar, its probable occlusal relationship with the unknown lower dentition is suggested. The posterolingual cusp with its two shearing crests and basin, appearing as a significant apomorphy, probably indicates the development of a better mode of mastication by grinding. The molar of Tikitherium copei, may thus be regarded as the earliest representative of several independent evolutionary developments of the grinding mechanism found in later mammalian groups such as the boreosphenidans, australosphenidans, shuotheriids, and docodonts.

Magnetotransport studies in La 0.7Ca 0.3Mn 1− xM xO 3 (M=Co and Ga)

The effect of doping a magnetic ion like Co and a non-magnetic ion like Ga at the Mn-site in La 0.7Ca 0.3MnO 3 was studied. ac magnetic susceptibility ( χ) measurements show a large suppression in the ferromagnetic transition temperature ( T C) for the Ga substituted compounds compared to that of the Co substituted compounds indicating that the decrease in ferromagnetic coupling in the former is due to smaller electronic bandwidth. The appearance of a prominent cusp in the χ– T curves for the Ga-compounds compared to the Co-compounds, even at low doping and also the deviation from the Curie–Weiss behaviour at low temperatures indicates a cluster glass kind of behaviour which is less pronounced in identical compositions of the Co-compounds. It has been seen that clustering of spins takes place either when the number of Mn 4+ ions [J. Appl. Phys. 85 (1999) 1663] or when the number of mobile charge carriers is reduced [J. Magn. Magn. Mater. 214 (2000) L149]. In this case the number of Mn 4+ ions is the same for identical compositions of Co and Ga-substituted compounds and hence the observed changes in T C can be attributed to the differences in the active electronic bandwidth. Resistivity measurements clearly confirm the presence of smaller electronic bandwidth in the Ga-compounds.

Gobiatherium (Mammalia: Dinocerata) from the Middle Eocene of Asia: Taxonomy and biochronological significance

GobiatheriumOsborn & Granger 1932 is a highly distinctive genus of dinoceratan known from Eocene strata in Kyrgyzstan, Kazakstan, and Nei Mongol and Henan, People’s Republic of China. Autapomorphies ofGobiatherium among uintatheriids are: skull long, narrow and shallow with a flat sagittal region; nasals strongly arched with bony septum connecting their anterior ends to the premaxillae; zygomatic arches broad and flare outward in region of glenoid fossae; lower jaw long and shallow with tall ascending ramus and without an inframandibular flange; no upper canines; lower canines greatly reduced; P2 has prominent cingular cusp on its anterolabial corner; metacarpals relatively long and slender. Two species ofGobiatherium are valid, the type speciesG. mirificumOsborn & Granger 1932 (=G.? major Qi 1987) and the much smaller and poorly knownG. minutumCheng & Ma 1990. G.?monolobotum Qi 1987 is a junior subjective synonym of the coryphodontid pantodontEudinoceras mongoliensisOsborn 1924. The distribution ofGobiatherium supports recognition of an Arshantan land-mammal ‘age’ (LMA) older than the Irdinmanhan LMA. The Arshantan LMA is redefined as the time interval between the first appearance datum (FAD) of the coryphodontid pantodontEudinoceras and the FAD of the brontotheriid perissodactylProtitan. Gobiatherium is one of several index taxa that allow mammalian assemblages of Arshantan age to be identified in China, Mongolia, Kazakstan and Kyrgyzstan.

Energy of (110) twist boundaries in [formula omitted] and its variation with induced strain

The energy of (110) twist boundaries in the Ag Ni system, as a function of twist angle, has been calculated using the embedded atom method (EAM). Two major cusps appear at 0° and 54.74° in addition to some less prominent cusps, including 35.26° and 70.53°. The variation of the boundary energy with coincidence strain has been studied. It is shown that calculations with small coincidence strains, up to about 2%, yield reasonable approximations to the energy of the strain-free interface. Perturbing the initial atomic positions in the two crystals significantly reduces the energy associated with some special boundaries, one of which is the 54.74° boundary. This is shown to be a consequence of a reconstruction of the boundary that is not accessible to the unperturbed crystals.

Characterization of the magnetic switching properties of single-domain particles

We investigated the characteristics of the magnetic switching of the single-domain particles (SDP) and studied its variation as a function of the field orientation, sweep rate, textural distribution and thermal relaxation effects. Our analysis is based on the non-interacting bi-state model using the probabilistic approach. The hysteresis loops measured at high sweep rates are much wider and the corresponding coercivities H c much larger than those taken at slower sweep rates. An increase in the field-angle orientation from the easy axis reduces the H c field, while decreasing the sweep rate flattens the trend of the variation of the curve until a very large angle is reached. The thermal factor KV/k BT, on the other hand, plays essentially the same role as the sweep rate does to the H c values: the larger the value of KV/k BT, the larger the value of H c . The transition energy barrier is roughly equal to ≈ 25 k B T if the field sweep period is 1 h, in agreement with the usual concept of the blocking temperature. However, this concept is subject to dispute if the sweep period is comparatively faster or slower. The variation of the reversible transverse susceptibility (RTS) with respect to the field orientation and thermal relaxation has also been systematically investigated. The cusps or trenches of the RTS due to thermal relaxation were shown to be substantially shaved or filled, while the corresponding H c values were shifted and reduced. The RTS of the SDPs may exhibit one, two or three prominent cusps at high values of KV/k BT depending upon the configuration and texture or randomness of the system given. The height of the cusp also varies with the field-orientation angles, and the corresponding switching-field distribution becomes broadened and decreases with the values of KV/k BT.

Thermal relaxation, textural and sweep rate effects on reversible transverse susceptibility of magnetic particles

We investigated the effect of thermal relaxation on reversible transverse susceptibility (RTS), χ, of single domain Stoner–Wohlfarth particles. We studied such an effect as a function of the orientation β of the easy axis with respect to the drive field (the z axis) within a non-interacting bi-state model. At β=00 one prominent cusp occurs for both χt1 and χt2 along the direction perpendicular to the drive field at H≂HC&amp;lt;HN (nucleation field) at high values KV/kBT (the ratio of the anisotropy energy versus thermal energy). The height of the cusp varies with β and reduces with decreasing values of KV/kBT. Correspondingly, the switching field distribution (SFD) becomes broadened with decreasing values of KV/kBT. The RTS may exhibit one, two, or three prominent cusps at high values of KV/kBT depending upon the textural distribution of the easy axes. For cos2 θ distribution of the easy axis about the x axis, y axis, and z axis there exists two, three, and one cusps, respectively. For random distribution of the easy axis in 2-D in the XZ and YZ plane there are one and three cusps, respectively, while there are three for random distribution in 3-D. Finally, we studied coercivity, RTS and SFD as a function of sweep rate. All these quantities are found to increase with sweeping frequency of the drive field. The peak field value of RTS is consistently the smallest of the three, while that of SFD is equal to or a shade larger than HC depending upon whether the hysteresis loop is rectangular or severely sheared.

Textural and sweep rate effects on transverse susceptibility of magnetic particles

Depending on the textural distribution of easy axes of the particles there could exhibit one, two or three prominent cusps in the curves for the reversible transverse susceptibility at high KV/kBT. Experimentally, the number of cusps detected at low KV/kBT may be one less since the cusp at Hc is fairly sensitive to thermal relaxation.

Black hole models for the dark matter in Draco and Ursa Minor

view Abstract Citations (8) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Black Hole Models for the Dark Matter in Draco and Ursa Minor Strobel, Nicolas V. ; Lake, George Abstract The stellar velocity dispersions of Draco and Ursa Minor have been used to infer large dark matter halos with central mass densities that are two orders of magnitude larger than found in brighter galaxies. We offer a different dark matter model. We fit the star count profiles using massive central black holes (1-2 x 10^7^ M_sun_) and investigate the agreement between this model and the latest velocity data. Such black holes produce the large observed velocity dispersions and create a density and distinctive velocity cusp close to the center. Star counts reaching the main sequence will lead to more accurate centering of the isopleths and may reveal a more prominent cusp. Publication: The Astrophysical Journal Pub Date: April 1994 DOI: 10.1086/187280 Bibcode: 1994ApJ...424L..83S Keywords: Black Holes (Astronomy); Cusps (Mathematics); Dark Matter; Halos; Milky Way Galaxy; Nomographs; Velocity; Ellipticity; Globular Clusters; Space Density; Astrophysics; COSMOLOGY: DARK MATTER; GALAXIES: LOCAL GROUP full text sources ADS | data products SIMBAD (2) NED (2)