Constraining the number of compact remnants near Sgr A*

NASA Astrophysics Data System (ADS)

Deegan, Patrick; Nayakshin, Sergei

2007-05-01

Due to dynamical friction stellar mass black holes and neutron stars are expected to form high-density cusps in the inner parsec of our Galaxy. These compact remnants, expected to number around 20000, may be accreting cold dense gas present there, and give rise to potentially observable X-ray emission. Here we build a simple but detailed time-dependent model of such emission. The possibility that these accretion flows are radiatively inefficient is taken into account and brings in some uncertainty in the conclusions. Despite this uncertainty, we find that at least several X-ray sources of this nature should be detectable with Chandra at any one time. Turning this issue around, we also ask a question of what current observational constraints might be telling us about the total number of compact remnants. In our `best guess' model, a cusp of ~40000 remnants overpredicts the number of discrete sources and the total X-ray luminosity of the inner parsec, and is hence ruled out. In the most radiatively inefficient scenario that we consider, the radiative efficiency is set to be as small as ɛ = 10-5. In this rather unlikely scenario, a cusp of ~40000 black holes would be allowed by the data, but several individual sources should still be visible. Future observations of the distribution and orbits of the cold ionized gas in the inner parsec of our Galaxy will put tighter constraints on the cusp of compact remnants.

Accretion onto stellar mass black holes

NASA Astrophysics Data System (ADS)

Deegan, Patrick

2009-12-01

I present work on the accretion onto stellar mass black holes in several scenarios. Due to dynamical friction stellar mass black holes are expected to form high density cusps in the inner parsec of our Galaxy. These compact remnants may be accreting cold dense gas present there, and give rise to potentially observable X-ray emission. I build a simple but detailed time-dependent model of such emission. Future observations of the distribution and orbits of the gas in the inner parsec of Sgr A* will put tighter constraints on the cusp of compact remnants. GRS 1915+105 is an LMXB, whose large orbital period implies a very large accretion disc and explains the extraordinary duration of its current outburst. I present smoothed particle hydrodynamic simulations of the accretion disc. The models includes the thermo-viscous instability, irradiation from the central object and wind loss. I find that the outburst of GRS 1915+105 should last a minimum of 20 years and up to ˜ 100 years if the irradiation is playing a significant role in this system. The predicted recurrence times are of the order of 104 years, making the duty cycle of GRS 1915+105 to be a few 0.1%. I present a simple analytical method to describe the observable behaviour of long period black hole LMXBs, similar to GRS 1915+105. Constructing two simple models for the surface density in the disc, outburst and quiescence times are calculated as a function of orbital period. LMXBs are an important constituent of the X-ray light function (XLF) of giant elliptical galaxies. I find that the duty cycle can vary considerably with orbital period, with implications for modelling the XLF.

Planetary camera observations of the central parsec of M32

NASA Technical Reports Server (NTRS)

Lauer, Tod R.; Faber, S. M.; Currie, Douglas G.; Ewald, S. P.; Groth, Edward J.; Hester, J. J.; Holtzman, Jon A.; Light, Robert M.; O'Neil, Earl J., Jr.; Shaya, Edward J.

1992-01-01

New HST observations are reported which show that the M32 nucleus is extremely dense, with rho0 not less than 4 x 10 exp 6 solar masses/cu pc if M32 has a core with rc not greater than 0.37 pc, and rho0 greater than 3 x 10 exp 7 solar masses/cu pc if it instead has a central r exp -1/2 cusp. Limits on the M32 core radius are nearly three times smaller, and those on the central density at least four times greater, than values inferred from the best ground-based observations. A central relaxation that is almost an order of magnitude shorter than previous estimates is inferred from the new core parameters; a shorter stellar collision time is also inferred. It is argued that a starlight cusp surrounds the central black hole.

Planetary camera observations of the central parsec of M32

NASA Astrophysics Data System (ADS)

Lauer, Tod R.; Faber, S. M.; Currie, Douglas G.; Ewald, S. P.; Groth, Edward J.; Hester, J. Jeff; Holtzman, Jon A.; Light, Robert M.; O'Neil, Earl J., Jr.; Shaya, Edward J.; Westphal, James A.

1992-08-01

New HST observations are reported which show that the M32 nucleus is extremely dense, with rho0 not less than 4 x 10 exp 6 solar masses/cu pc if M32 has a core with rc not greater than 0.37 pc, and rho0 greater than 3 x 10 exp 7 solar masses/cu pc if it instead has a central r exp -1/2 cusp. Limits on the M32 core radius are nearly three times smaller, and those on the central density at least four times greater, than values inferred from the best ground-based observations. A central relaxation that is almost an order of magnitude shorter than previous estimates is inferred from the new core parameters; a shorter stellar collision time is also inferred. It is argued that a starlight cusp surrounds the central black hole.

Associations between Carabelli trait and cusp areas in human permanent maxillary first molars.

PubMed

Kondo, Shintaro; Townsend, Grant C

2006-02-01

Few dental anthropological studies have investigated the associations between tooth crown size and crown traits in humans using quantitative methods. We tested several hypotheses about overall crown size, individual cusp areas, and expression of Carabelli cusps in human permanent first molars by obtaining data from standardized occlusal photographs of 308 Australians of European descent (171 males and 137 females). Specifically, we aimed to calculate the areas of the four main molar cusps, and also Carabelli cusp, and to compare the relative variability of cusp areas in relation to timing of development. We also aimed to compare cusp areas between males and females and to describe how Carabelli cusp interacted with other molar cusps. Measurements included maximum crown diameters (mesiodistal and buccolingual crown diameters), the areas of the four main cusps, and the area of Carabelli cusp. The pattern of relative variability in absolute areas of molar cusps corresponded with their order of formation, the first-forming paracone displaying the least variation, and the last-forming Carabelli cusp showing the greatest. Overall crown size and areas of individual cusps all showed sexual dimorphism, with values in males exceeding those in females. Sexual dimorphism was smallest for paracone area and greatest for Carabelli cusp area. Overall crown size and cusp areas were larger in individuals displaying a Carabelli cusp, especially the hypocone area. Although the combined area of the protocone and a Carabelli cusp was greater in cuspal forms than noncuspal forms, protocone area alone was significantly smaller in the former. Our findings lead us to propose that, in individuals with the genotype for Carabelli trait expression, larger molar crowns are more likely to display Carabelli cusps, whereas molars with smaller crowns are more likely to display reduced forms of expression of the trait. We suggest that the pattern of folding of the internal enamel epithelium in developing molar crowns, particularly in the protocone region, can be modified by a developing Carabelli cusp.

The distribution of stars around the Milky Way's central black hole. II. Diffuse light from sub-giants and dwarfs

NASA Astrophysics Data System (ADS)

Schödel, R.; Gallego-Cano, E.; Dong, H.; Nogueras-Lara, F.; Gallego-Calvente, A. T.; Amaro-Seoane, P.; Baumgardt, H.

2018-01-01

Context. This is the second of three papers that search for the predicted stellar cusp around the Milky Way's central black hole, Sagittarius A*, with new data and methods. Aims: We aim to infer the distribution of the faintest stellar population currently accessible through observations around Sagittarius A*. Methods: We used adaptive optics assisted high angular resolution images obtained with the NACO instrument at the ESO VLT. Through optimised PSF fitting we removed the light from all detected stars above a given magnitude limit. Subsequently we analysed the remaining, diffuse light density. Systematic uncertainties were constrained by the use of data from different observing epochs and obtained with different filters. We show that it is necessary to correct for the diffuse emission from the mini-spiral, which would otherwise lead to a systematically biased light density profile. We used a Paschen α map obtained with the Hubble Space Telescope for this purpose. Results: The azimuthally averaged diffuse surface light density profile within a projected distance of R ≲ 0.5 pc from Sagittarius A* can be described consistently by a single power law with an exponent of Γ = 0.26 ± 0.02stat ± 0.05sys, similar to what has been found for the surface number density of faint stars in Paper I. Conclusions: The analysed diffuse light arises from sub-giant and main-sequence stars with Ks ≈ 19-22 with masses of 0.8-1.5 M⊙. These stars can be old enough to be dynamically relaxed. The observed power-law profile and its slope are consistent with the existence of a relaxed stellar cusp around the Milky Way's central black hole. We find that a Nuker law provides an adequate description of the nuclear cluster's intrinsic shape (assuming spherical symmetry). The 3D power-law slope near Sgr A* is γ = 1.13 ± 0.03model ± 0.05sys. The stellar density decreases more steeply beyond a break radius of about 3 pc, which corresponds roughly to the radius of influence of the massive black hole. At a distance of 0.01 pc from the black hole, we estimate a stellar mass density of 2.6 ± 0.3 × 107 M⊙ pc-3 and a total enclosed stellar mass of 180 ± 30 M⊙. These estimates assume a constant mass-to-light ratio and do not take stellar remnants into account. The fact that a flat projected surface density is observed for old giants at projected distances R ≲ 0.3 pc implies that some mechanism may have altered their appearance or distribution.

Probing Black Holes With Gravitational Radiation

NASA Astrophysics Data System (ADS)

Cornish, Neil J.

2006-09-01

Gravitational radiation can provide unique insights into the dynamics and evolution of black holes. Gravitational waveforms encode detailed information about the spacetime geometry, much as the sounds made by a musical instrument reflect the geometry of the instrument. The LISA gravitational wave observatory will be able to record black holes colliding out to the edge of the visible Universe, with an expected event rate of tens to thousands per year. LISA has unmatched capabilities for studying the role of black holes in galactic evolution, in particular, by studying the mergers of seed black holes at very high redshift, z > 5. Merger events at lower redshift will be detected at extremely high signal-to-noise, allowing for precision tests of the black hole paradigm. Below z=1 LISA will be able to record stellar remnants falling into supermassive black holes. These extreme mass ratio inspiral events will yield insights into the dynamics of galactic cusps, and the brighter events will provide incredibly precise tests of strong field, dynamical gravity.

Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions

NASA Astrophysics Data System (ADS)

Strigari, Louis E.; Frenk, Carlos S.; White, Simon D. M.

2018-06-01

We compare the transverse velocity dispersions recently measured within the Sculptor dwarf spheroidal galaxy to the predictions of our previously published dynamical model. This was designed to fit the observed number count and velocity dispersion profiles of both metal-rich and metal-poor stars, both in cored and in cusped potentials. At the projected radius where the proper motions (PMs) were measured, this model (with no change in parameters) predicts transverse dispersions in the range of 6–9.5 km s‑1, with the tangential dispersion about 1 km s‑1 larger than the (projected) radial dispersion. Both dispersions are predicted to be about 1 km s‑1 larger for metal-poor than for metal-rich stars. At this projected radius, cored and cusped potentials predict almost identical transverse dispersions. The measured tangential dispersion (8.5 ± 3.2 km s‑1) agrees remarkably well with these predictions, while the measured radial dispersion (11.5 ± 4.3 km s‑1) differs only at about the 1σ level. Thus, the PM data are in excellent agreement with previous data, but do not help to distinguish between cored and cusped potentials. This will require velocity dispersion data (either from PMs or from radial velocities) with uncertainties well below 1 km s‑1 over a range of projected radii.

Design of a cusped field thruster for drag-free flight

NASA Astrophysics Data System (ADS)

Liu, H.; Chen, P. B.; Sun, Q. Q.; Hu, P.; Meng, Y. C.; Mao, W.; Yu, D. R.

2016-09-01

Drag-free flight has played a more and more important role in many space missions. The thrust control system is the key unit to achieve drag-free flight by providing a precise compensation for the disturbing force except gravity. The cusped field thruster has shown a significant potential to be capable of the function due to its long life, high efficiency, and simplicity. This paper demonstrates a cusped field thruster's feasibility in drag-free flight based on its instinctive characteristics and describes a detailed design of a cusped field thruster made by Harbin Institute of Technology (HIT). Furthermore, the performance test is conducted, which shows that the cusped field thruster can achieve a continuously variable thrust from 1 to 20 mN with a low noise and high resolution below 650 W, and the specific impulse can achieve 1800 s under a thrust of 18 mN and discharge voltage of 1000 V. The thruster's overall performance indicates that the cusped field thruster is quite capable of achieving drag-free flight. With the further optimization, the cusped field thruster will exhibit a more extensive application value.

Examination of ceramic restoration adhesive coverage in cusp-replacement premolar using acoustic emission under fatigue testing.

PubMed

Chang, Yen-Hsiang; Yu, Jin-Jie; Lin, Chun-Li

2014-12-13

This study investigates CAD/CAM ceramic cusp-replacing restoration resistance with and without buccal cusp replacement under static and dynamic cyclic loads, monitored using the acoustic emission (AE) technique. The cavity was designed in a typical MODP (mesial-occlusal-distal-palatal) restoration failure shape when the palatal cusp has been lost. Two ceramic restorations [without coverage (WOC) and with (WC) buccal cuspal coverage with 2.0 mm reduction in cuspal height] were prepared to perform the fracture and fatigue tests with normal (200 N) and high (600 N) occlusal forces. The load versus AE signals in the fracture and fatigue tests were recorded to evaluate the restored tooth failure resistance. The results showed that non-significant differences in load value in the fracture test and the accumulated number of AE signals under normal occlusal force (200 N) in the fatigue test were found between with and without buccal cuspal coverage restorations. The first AE activity occurring for the WOC restoration was lower than that for the WC restoration in the fracture test. The number of AE signals increased with the cyclic load number. The accumulated number of AE signals for the WOC restoration was 187, higher than that (85) for the WC restoration under 600 N in the fatigue test. The AE technique and fatigue tests employed in this study were used as an assessment tool to evaluate the resistances in large CAD/CAM ceramic restorations. Non-significant differences in the tested fracture loads and accumulated number of AE signals under normal occlusal force (200 N) between different restorations indicated that aggressive treatment (with coverage preparation) in palatal cusp-replacing ceramic premolars require more attention for preserving and protecting the remaining tooth.

The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

NASA Astrophysics Data System (ADS)

Zocchi, Alice; Gieles, Mark; Hénault-Brunet, Vincent

2018-06-01

The search for intermediate-mass black holes (IMBHs) in the centre of globular clusters is often based on the observation of a central cusp in the surface brightness profile and a rise towards the centre in the velocity dispersion profiles. Similar signatures, however, could result from other effects, that need to be taken into account in order to determine the presence (or the absence) of an IMBH in these stellar systems. Following our previous exploration of the role of radial anisotropy in shaping these observational signatures, we analyse here the effects produced by the presence of a population of centrally concentrated stellar-mass black holes. We fit dynamical models to ω Cen data, and we show that models with ˜5% of their mass in black holes (consistent with ˜100% retention fraction after natal kicks) can reproduce the data. When simultaneously considering both radial anisotropy and mass segregation, the best-fit model includes a smaller population of remnants, and a less extreme degree of anisotropy with respect to the models that include only one of these features. These results underline that before conclusions about putative IMBHs can be made, the effects of stellar-mass black holes and radial anisotropy need to be properly accounted for.

Methods for quantitative measurement of tooth wear using the area and volume of virtual model cusps.

PubMed

Kim, Soo-Hyun; Park, Young-Seok; Kim, Min-Kyoung; Kim, Sulhee; Lee, Seung-Pyo

2018-04-01

Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methods of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models. The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed. The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ρ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference ( P <0.01) from the other cusps in the paired t -test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp. Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear.

Probing dark matter with star clusters: a dark matter core in the ultra-faint dwarf Eridanus II

NASA Astrophysics Data System (ADS)

Contenta, Filippo; Balbinot, Eduardo; Petts, James A.; Read, Justin I.; Gieles, Mark; Collins, Michelle L. M.; Peñarrubia, Jorge; Delorme, Maxime; Gualandris, Alessia

2018-05-01

We present a new technique to probe the central dark matter (DM) density profile of galaxies that harnesses both the survival and observed properties of star clusters. As a first application, we apply our method to the `ultra-faint' dwarf Eridanus II (Eri II) that has a lone star cluster ˜45 pc from its centre. Using a grid of collisional N-body simulations, incorporating the effects of stellar evolution, external tides and dynamical friction, we show that a DM core for Eri II naturally reproduces the size and the projected position of its star cluster. By contrast, a dense cusped galaxy requires the cluster to lie implausibly far from the centre of Eri II (>1 kpc), with a high inclination orbit that must be observed at a particular orbital phase. Our results, therefore, favour a DM core. This implies that either a cold DM cusp was `heated up' at the centre of Eri II by bursty star formation or we are seeing an evidence for physics beyond cold DM.

Enamel microstructure and microstrain in the fracture of human and pig molar cusps.

PubMed

Popowics, T E; Rensberger, J M; Herring, S W

2004-08-01

The role of microstructure in enamel strain and breakage was investigated in human molar cusps and those of the pig, Sus scrofa. Rosette strain gauges were affixed to cusp surfaces (buccal human M3, n=15, and lingual pig M1, n=13), and a compressive load was applied to individual cusps using an MTS materials testing machine. Load and strain data were recorded simultaneously until cusp fracture, and these data were used to estimate enamel stresses, principal strains, and stiffness. Fractured and polished enamel fragments were examined in multiple planes using scanning electron microscopy (SEM). Human cusp enamel showed greater stiffness than pig enamel (P=0.02), and tensile stress at yield was higher (17.9 N/mm2 in humans versus 8.9 N/mm2 in pigs, P=0.06). SEM revealed enamel rod decussation in both human and pig enamel; however, only pig enamel showed a decussation plane between rod and inter-rod crystallites. Human inter-rod enamel was densely packed between rods, whereas in pig enamel, inter-rod enamel formed partitions between rows of enamel rods. Overall, human enamel structure enabled molar cusps to withstand horizontal tensile stress during both elastic and plastic phases of compressive loading. In contrast, pig cusp enamel was less resistant to horizontal tensile stresses, but appeared to fortify the enamel against crack propagation in multiple directions. These structural and biomechanical differences in cusp enamel are likely to reflect species-level differences in occlusal function.

The presence of accessory cusps in chimpanzee lower molars is consistent with a patterning cascade model of development

PubMed Central

Skinner, Matthew M; Gunz, Philipp

2010-01-01

Tooth crown morphology is of primary importance in fossil primate systematics and understanding the developmental basis of its variation facilitates phenotypic analyses of fossil teeth. Lower molars of species in the chimp/human clade (including fossil hominins) possess between four and seven cusps and this variability has been implicated in alpha taxonomy and phylogenetic systematics. What is known about the developmental basis of variation in cusp number – based primarily on experimental studies of rodent molars – suggests that cusps form under a morphodynamic, patterning cascade model involving the iterative formation of enamel knots. In this study we test whether variation in cusp 6 (C6) presence in common chimpanzee and bonobo lower molars (n = 55) is consistent with predictions derived from the patterning cascade model. Using microcomputed tomography we imaged the enamel-dentine junction of lower molars and used geometric morphometrics to examine shape variation in the molar crown correlated with variation in C6 presence (in particular the size and spacing of the dentine horns). Results indicate that C6 presence is consistent with predictions of a patterning cascade model, with larger molars exhibiting a higher frequency of C6 and with the location and size of later-forming cusps correlated with C6 variation. These results demonstrate that a patterning cascade model is appropriate for interpreting cusp variation in Pan and have implications for cusp nomenclature and the use of accessory cusp morphology in primate systematics. PMID:20629983

Fracture Resistance of Teeth Restored with Direct and Indirect Composite Restorations

PubMed Central

Torabzadeh, Hassan; Ghasemi, Amir; Dabestani, Atoosa; Razmavar, Sara

2013-01-01

Objective: Tooth fracture is a common dental problem. By extension of cavity dimensions, the remaining tooth structure weakens and occlusal forces may cause tooth fracture. The aim of this study was to evaluate and compare the fracture resistance of teeth restored with direct and indirect composite restorations. Materials and Methods: Sixty-five sound maxillary premolar teeth were chosen and randomly divided into five groups each comprising thirteen. Fifty-two teeth received mesio-occluso-distal (MOD) cavities with 4.5mm bucco-lingual width, 4mm pulpal depth and 3mm gingival depth and were divided into the following four groups. G-1: restored with direct composite (Z-250, 3M/ESPE) with cusp coverage, G-2: restored with direct composite (Z-250) without cusp coverage, G-3: restored with direct composite (Gradia, GC-international) with cusp coverage, G-4: restored with indirect composite (Gradia, GC-International) with cusp coverage. Intact teeth were used in G-5 as control. The teeth were subjected to a compressive axial loading using a 4 mm diameter rod in a universal testing machine with 1 mm/min speed. Data were analyzed using one-way ANOVA and Tukey tests. Results: The mean fracture strength recorded was: G-1: 1148.46N±262, G-2: 791.54N±235, G-3: 880.00N±123, G-4: 800.00N±187, G-5: 1051.54N±345. ANOVA revealed significant differences between groups (p<0.05). Tukey test showed significant difference between group 1 and the other groups. There was no significant difference among other groups. Conclusion: Direct composite (Z-250) with cusp coverage is a desirable treatment for weakened teeth. Treatment with Z-250 without cusp coverage, direct and indirect Gradia with cusp coverage restored the strength of the teeth to the level of intact teeth. PMID:24910649

A central black hole in M32

NASA Technical Reports Server (NTRS)

Tonry, John L.

1987-01-01

Observations are presented of the stellar rotation and velocity dispersion in M32. The projected rotation curve has an unresolved cusp at the center, with an amplitude of at least 60 km/s. The stellar velocity dispersion is constant at 56 + or - 5 km/s to a radius of 20 arcsec; a central bump in the observed dispersion is an artifact due to the rotation. The form of the rotation is such that isophotes have constant angular rotation velocity. The three-dimensional rotation field is modeled and the internal mean rotation of the stars around the center of M32 must reach at least 90 km/s at a radius of 2 pc. Hydrostatic equilibrium then requires 3-10 x 10 to the 6th solar masses of dark mass within the central parsec of M32. The possibility that M32 is undergoing core collapse and that this dark mass consists of dark stellar remnants is discussed, but ultimately rejected because the time scale for core collapse of M32 should be 2000 Hubble times. A more likely explanation of this dark mass, especially because of the presence of an X-ray point source at the center of M32, is a massive black hole.

Cuspal reinforcement in endodontically treated molars.

PubMed

Uyehara, M Y; Davis, R D; Overton, J D

1999-01-01

This in vitro study compared the ability of horizontal pins and a dental adhesive to reinforce the facial cusps of endodontically treated mandibular molars. Seventy-two mandibular molars were divided into six groups and mounted in acrylic blocks (n = 12). In Groups 1-5 standardized endodontic access and instrumentation in the coronal one-third of each root canal were completed. In Groups 1-4 the lingual cusps were reduced, leaving the buccal cusps intact. The facial cusps of the teeth in each group received one of the following modes of reinforcement: Group 1--no reinforcement; Group 2--dentin adhesive (Amalgambond Plus); Group 3--two horizontal TMS Minim pins; Group 4--two horizontal TMS Minim pins and Amalgambond Plus. Teeth in Group 5 were prepared for and restored with a complete cuspal coverage amalgam restoration using four vertical TMS Minim pins. Group 6 consisted of intact natural teeth. Using an Instron Universal Testing Machine, the lingual slope of the facial cusp of each specimen was loaded to failure using a compressive force applied at an angle 60 degrees to the long axis of the tooth. The mean fracture strengths for all groups were analyzed using a one-way ANOVA and Student-Newman-Keuls multiple range test (alpha = 0.05). Fracture patterns and modes of failure were also evaluated. The intact teeth (Group 6) were significantly more fracture resistant than all other groups, with the exception of Group 4 (combination of pins and adhesive). Group 1 (non-reinforced teeth) was significantly weaker than all other groups. Groups 2-4 (specimens with reinforced cusps) were not significantly different from each other. The use of horizontal pins or a combination of horizontal pins plus dentin adhesive for cuspal reinforcement resulted in significantly more teeth demonstrating favorable fracture patterns than did the use of adhesives alone. The buccal cusps of endodontically treated mandibular molars reinforced with a combination of horizontal pins and dentin adhesive were not significantly weaker than intact teeth. Of the restored teeth, those which had buccal cusps reinforced with horizontal pins and those treated with complete cuspal coverage amalgam restorations exhibited the most favorable restorative prognosis following cusp fracture.

Molar cusp deformation evaluated by micro-CT and enamel crack formation to compare incremental and bulk-filling techniques.

PubMed

Oliveira, Laís Rani Sales; Braga, Stella Sueli Lourenço; Bicalho, Aline Arêdes; Ribeiro, Maria Tereza Hordones; Price, Richard Bengt; Soares, Carlos José

2018-07-01

To describe a method of measuring the molar cusp deformation using micro-computed tomography (micro-CT), the propagation of enamel cracks using transillumination, and the effects of hygroscopic expansion after incremental and bulk-filling resin composite restorations. Twenty human molars received standardized Class II mesio-occlusal-distal cavity preparations. They were restored with either a bulk-fill resin composite, X-tra fil (XTRA), or a conventional resin composite, Filtek Z100 (Z100). The resin composites were tested for post-gel shrinkage using a strain gauge method. Cusp deformation (CD) was evaluated using the images obtained using a micro-CT protocol and using a strain-gauge method. Enamel cracks were detected using transillumination. The post-gel shrinkage of Z100 was higher than XTRA (P < 0.001). The amount of cusp deformation produced using Z100 was higher compared to XTRA, irrespective of the measurement method used (P < 0.001). The thinner lingual cusp always had a higher CD than the buccal cusp, irrespective of the measurement method (P < 0.001). A positive correlation (r = 0.78) was found between cusp deformation measured by micro-CT or by the strain-gauge method. After hygroscopic expansion of the resin composite, the cusp displacement recovered around 85% (P < 0.001). After restoration, Z100 produced more cracks than XTRA (P = 0.012). Micro-CT was an effective method for evaluating the cusp deformation. Transillumination was effective for detecting enamel cracks. There were fewer negative effects of polymerization shrinkage in bulk-fill resin restorations using XTRA than for the conventional incremental filling technique using conventional composite resin Z100. Shrinkage and cusp deformation are directly related to the formation of enamel cracks. Cusp deformation and crack propagation may increase the risk of tooth fracture. Copyright © 2018 Elsevier Ltd. All rights reserved.

Methods for quantitative measurement of tooth wear using the area and volume of virtual model cusps

PubMed Central

2018-01-01

Purpose Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methods of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models. Methods The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed. Results The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ρ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference (P<0.01) from the other cusps in the paired t-test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp. Conclusions Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear. PMID:29770241

Intermediate mass black holes in AGN discs - I. Production and growth

NASA Astrophysics Data System (ADS)

McKernan, B.; Ford, K. E. S.; Lyra, W.; Perets, H. B.

2012-09-01

Here we propose a mechanism for efficiently growing intermediate mass black holes (IMBH) in discs around supermassive black holes. Stellar mass objects can efficiently agglomerate when facilitated by the gas disc. Stars, compact objects and binaries can migrate, accrete and merge within discs around supermassive black holes. While dynamical heating by cusp stars excites the velocity dispersion of nuclear cluster objects (NCOs) in the disc, gas in the disc damps NCO orbits. If gas damping dominates, NCOs remain in the disc with circularized orbits and large collision cross-sections. IMBH seeds can grow extremely rapidly by collisions with disc NCOs at low relative velocities, allowing for super-Eddington growth rates. Once an IMBH seed has cleared out its feeding zone of disc NCOs, growth of IMBH seeds can become dominated by gas accretion from the active galactic nucleus (AGN) disc. However, the IMBH can migrate in the disc and expand its feeding zone, permitting a super-Eddington accretion rate to continue. Growth of IMBH seeds via NCO collisions is enhanced by a pile-up of migrators. We highlight the remarkable parallel between the growth of IMBH in AGN discs with models of giant planet growth in protoplanetary discs. If an IMBH becomes massive enough it can open a gap in the AGN disc. IMBH migration in AGN discs may stall, allowing them to survive the end of the AGN phase and remain in galactic nuclei. Our proposed mechanisms should be more efficient at growing IMBH in AGN discs than the standard model of IMBH growth in stellar clusters. Dynamical heating of disc NCOs by cusp stars is transferred to the gas in an AGN disc helping to maintain the outer disc against gravitational instability. Model predictions, observational constraints and implications are discussed in a companion paper (Paper II).

Ceramic inlays and partial ceramic crowns: influence of remaining cusp wall thickness on the marginal integrity and enamel crack formation in vitro.

PubMed

Krifka, Stephanie; Anthofer, Thomas; Fritzsch, Marcus; Hiller, Karl-Anton; Schmalz, Gottfried; Federlin, Marianne

2009-01-01

No information is currently available about what the critical cavity wall thickness is and its influence upon 1) the marginal integrity of ceramic inlays (CI) and partial ceramic crowns (PCC) and 2) the crack formation of dental tissues. This in vitro study of CI and PCC tested the effects of different remaining cusp wall thicknesses on marginal integrity and enamel crack formation. CI (n = 25) and PCC (n = 26) preparations were performed in extracted human molars. Functional cusps of CI and PCC were adjusted to a 2.5 mm thickness; for PCC, the functional cusps were reduced to a thickness of 2.0 mm. Non-functional cusps were adjusted to wall thicknesses of 1) 1.0 mm and 2) 2.0 mm. Ceramic restorations (Vita Mark II, Cerec3 System) were fabricated and adhesively luted to the cavities with Excite/Variolink II. The specimens were exposed to thermocycling and central mechanical loading (TCML: 5000 x 5 degrees C-55 degrees C; 30 seconds/cycle; 500000 x 72.5N, 1.6Hz). Marginal integrity was assessed by evaluating a) dye penetration (fuchsin) on multiple sections after TCML and by using b) quantitative margin analysis in the scanning electron microscope (SEM) before and after TCML. Ceramic- and tooth-luting agent interfaces (LA) were evaluated separately. Enamel cracks were documented under a reflective light microscope. The data were statistically analyzed with the Mann Whitney U-test (alpha = 0.05) and the Error Rates Method (ERM). Crack formation was analyzed with the Chi-Square-test (alpha = 0.05) and ERM. In general, the remaining cusp wall thickness, interface, cavity design and TCML had no statistically significant influence on marginal integrity for both CI and PCC (ERM). Single pairwise comparisons showed that the CI and PCC of Group 2 had a tendency towards less microleakage along the dentin/LA interface than Group 1. Cavity design and location had no statistically significant influence on crack formation, but the specimens with 1.0 mm of remaining wall thickness had statistically significantly more crack formation after TCML than the group with 2.0 mm of remaining cusp wall thickness for CI. The remaining cusp wall thickness of non-functional cusps of adhesively bonded restorations (especially for CI) should have a thickness of at least 2.0 mm to avoid cracks and marginal deficiency at the dentin/LA interface.

X-ray constraints on the number of stellar mass black holes in the inner parsec

NASA Astrophysics Data System (ADS)

Deegan, Patrick; Nayakshin, Sergei

2006-12-01

Due to dynamical friction stellar mass black holes should form a cusp in the inner parsec. Calculations [5, 6] show that approximately 20 thousand black holes would be present in a sphere with radius of about a parsec around Sgr A*. The presence of these objects opens up the possibility that they might be accreting ''cool'' gas (i.e. the Minispiral) as discussed by Morris [6]. Here we calculate the X-ray emission expected from these black holes as a method to constrain their population. We find that the data limits the total number of such black holes to around 10 - 20 thousand. Even a much smaller number of such black holes, i.e. 5 thousand, is sufficient to produce several sources with X-ray luminosity above Lx ~ 1033 erg s-1 at any one time. We suggest that some of the discrete X-ray sources observed by Muno [7] with Chandra in the inner parsec may be such ''fake X-ray binaries''.

Enhanced Discharge Performance in a Ring Cusp Plasma Source

NASA Technical Reports Server (NTRS)

Foster, John E.; Patterson, Michael J.

2000-01-01

There is a need for a lightweight, low power ion thruster for space science missions. Such an ion thruster is under development at NASA Glenn Research Center. In an effort to better understand the discharge performance of this thruster, a thruster discharge chamber with an anode containing electrically isolated electrodes at the cusps was fabricated and tested. Characteristics of this ring cusp ion discharge were measured without ion beam extraction. Discharge current was measured at collection electrodes located at the magnetic cusps and at the anode body itself. Discharge performance and plasma properties were measured as a function of power, which was varied between 20 and 50 W. It was found that ion production costs decreased by as much as 20 percent when the two most downstream cusp electrodes were allowed to float. Floating the electrodes did not give rise to a significant increase in discharge power even though the plasma density increased markedly. The improved performance is attributed to enhanced electron containment.

Test of an argon cusp plasma for tin LPP power scaling

NASA Astrophysics Data System (ADS)

McGeoch, Malcolm W.

2015-03-01

Scaling the power of the tin droplet laser-produced-plasma (LPP) extreme ultraviolet (EUV) source to 500W has eluded the industry after a decade of effort. In 2014 we proposed [2] a solution: placing the laser-plasma interaction region within an argon plasma in a magnetic cusp. This would serve to ionize tin atoms and guide them to a large area annular beam dump. We have since demonstrated the feasibility of this approach. We present first results from a full-scale test plasma at power levels relevant to the generation of at least 200W, showing both that the argon cusp plasma is very stable, and that its geometrical properties are ideal for the transport of exhaust power and tin to the beam dump.

Renormalization-group theory for the eddy viscosity in subgrid modeling

NASA Technical Reports Server (NTRS)

Zhou, YE; Vahala, George; Hossain, Murshed

1988-01-01

Renormalization-group theory is applied to incompressible three-dimensional Navier-Stokes turbulence so as to eliminate unresolvable small scales. The renormalized Navier-Stokes equation now includes a triple nonlinearity with the eddy viscosity exhibiting a mild cusp behavior, in qualitative agreement with the test-field model results of Kraichnan. For the cusp behavior to arise, not only is the triple nonlinearity necessary but the effects of pressure must be incorporated in the triple term. The renormalized eddy viscosity will not exhibit a cusp behavior if it is assumed that a spectral gap exists between the large and small scales.

A morphometric analysis of maxillary molar crowns of Middle-Late Pleistocene hominins.

PubMed

Bailey, Shara E

2004-09-01

This study explores the significance of shape differences in the maxillary first molar crowns of Neandertals and anatomically modern humans. It uses morphometric analysis to quantify these differences and to investigate how the orientation of major cusps, relative cusp base areas and occlusal polygon area influence crown shape. The aims of this study were to 1) quantify these data to test whether the tooth shapes of Neandertals and anatomically modern humans differ significantly and 2) to explore if either of the shapes is derived relative to earlier fossil hominins. Data were collected from digital occlusal photographs using image-processing software. Cusp angles, relative cusp base areas and occlusal polygon areas were measured on Neandertals (n=15), contemporary modern humans (n=62), Upper Paleolithic humans (n=6), early anatomically modern humans (n=3) and Homo erectus (n=3). Univariate and multivariate statistical tests were used to evaluate the differences between contemporary modern humans and Neandertals, while the much sparser data sets from the other fossil samples were included primarily for comparison. Statistically significant differences reflecting overall crown shape and internal placement of the crown apices were found. Neandertals are distinguished from contemporary humans by possessing maxillary first molars that 1) are markedly skewed; 2) possess a narrower distal segment of the occlusal polygon compared to the mesial segment; 3) possess a significantly smaller metacone and a significantly larger hypocone; and 4) possess a significantly smaller relative occlusal polygon area reflecting internally placed cusps. Differences in relative cusp base areas of the hypocone and metacone may contribute to the shape differences observed in Neandertals. However, early anatomically modern humans possessing a pattern of relative cusp base areas similar to Neandertals lack their unusual shape. That the morphology observed in non-Neandertal fossil hominins is more anatomically modern human-like than Neandertal-like, suggests that this distinctive morphology may be derived in Neandertals.

Ultraluminous Infrared Mergers: Elliptical Galaxies in Formation?

NASA Astrophysics Data System (ADS)

Genzel, R.; Tacconi, L. J.; Rigopoulou, D.; Lutz, D.; Tecza, M.

2001-12-01

We report high-quality near-IR spectroscopy of 12 ultraluminous infrared galaxy mergers (ULIRGs). Our new VLT and Keck data provide ~0.5" resolution, stellar and gas kinematics of these galaxies, most of which are compact systems in the last merger stages. We confirm that ULIRG mergers are ``ellipticals in formation.'' Random motions dominate their stellar dynamics, but significant rotation is common. Gasdynamics and stellar dynamics are decoupled in most systems. ULIRGs fall on or near the fundamental plane of hot stellar systems, and especially on its less evolution-sensitive, reff-σ projection. The ULIRG velocity dispersion distribution, their location in the fundamental plane, and their distribution of vrotsini/σ closely resemble those of intermediate-mass (~L*), elliptical galaxies with moderate rotation. As a group ULIRGs do not resemble giant ellipticals with large cores and little rotation. Our results are in good agreement with other recent studies indicating that disky ellipticals with compact cores or cusps can form through dissipative mergers of gas-rich disk galaxies while giant ellipticals with large cores have a different formation history. Based on observations at the European Southern Observatory, Chile (ESO 65.N-0266, 65.N-0289), and on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, The University of California, and the National Aeronautics and Space Administration. The Keck Observatory was made possible by the general financial support by the W. M. Keck Foundation.

Beach-cusp formation

USGS Publications Warehouse

Sallenger, A.H.

1979-01-01

Field experiments on beach-cusp formation were undertaken to document how the cuspate form develops and to test the edge-wave hypothesis on the uniform spacing of cusps. These involved observations of cusps forming from an initially plane foreshore. The cuspate form was observed to be a product of swash modification of an intertidal beach ridge as follows. A ridge, cut by a series of channels quasi-equally spaced along its length, was deposited onto the lower foreshore. The ridge migrated shoreward with flood tide, while the longshore positions of the channels remained fixed. On ebb tide, changes in swash circulation over the ridge allowed the upwash to flow shoreward through the channels and the channel mouths were eroded progressively wider until adjacent mouths met, effecting a cuspate shape. Measured spacings of cusps, ranging in size from less than 1 m to more than 12 m, agree well with computed spacings due to either zero-mode subharmonic or zero-mode synchronous edge waves. Edge-wave-induced longshore variations in run up will cause water ponded behind a ridge to converge at points of low swash and flow seaward as relatively narrow currents eroding channels spaced at one edge-wave wavelength for synchronous edge waves or one half wavelength for subharmonic edge waves. The channels are subsequently modified into cusp troughs as described above.

A web-based tool for the Comprehensive Unit-based Safety Program (CUSP).

PubMed

Pronovost, Peter J; King, Jay; Holzmueller, Christine G; Sawyer, Melinda; Bivens, Shauna; Michael, Michelle; Haig, Kathy; Paine, Lori; Moore, Dana; Miller, Marlene

2006-03-01

An organization's ability to change is driven by its culture, which in turn has a significant impact on safety. The six-step Comprehensive Unit-Based Safety Program (CUSP) is intended to improve local culture and safety. A Web-based project management tool for CUSP was developed and then pilot tested at two hospitals. HOW ECUSP WORKS: Once a patient safety concern is identified (step 3), a unit-level interdisciplinary safety committee determines issue criticality and starts up the projects (step 4), which are managed using project management tools within eCUSP (step 5). On a project's completion, the results are disseminated through a shared story (step 6). OSF St. Joseph's Medical Center-The Medical Birthing Center (Bloomington, Illinois), identified 11 safety issues, implemented 11 projects, and created 9 shared stories--including one for its Armband Project. The Johns Hopkins Hospital (Baltimore) Medical Progressive Care (MPC4) Unit identified 5 safety issues and implemented 4 ongoing projects, including the intravenous (IV) Tubing Compliance Project. The eCUSP tool's success depends on an organizational commitment to creating a culture of safety.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morscher, Meagan; Pattabiraman, Bharath; Rodriguez, Carl

Our current understanding of the stellar initial mass function and massive star evolution suggests that young globular clusters (GCs) may have formed hundreds to thousands of stellar-mass black holes (BHs), the remnants of stars with initial masses from ∼20-100 M {sub ☉}. Birth kicks from supernova explosions may eject some BHs from their birth clusters, but most should be retained. Using a Monte Carlo method we investigate the long-term dynamical evolution of GCs containing large numbers of stellar BHs. We describe numerical results for 42 models, covering a broad range of realistic initial conditions, including up to 1.6 × 10{supmore » 6} stars. In almost all models we find that significant numbers of BHs (up to ∼10{sup 3}) are retained all the way to the present. This is in contrast to previous theoretical expectations that most BHs should be ejected dynamically within a few gigayears The main reason for this difference is that core collapse driven by BHs (through the Spitzer {sup m}ass segregation instability{sup )} is easily reverted through three-body processes, and involves only a small number of the most massive BHs, while lower-mass BHs remain well-mixed with ordinary stars far from the central cusp. Thus the rapid segregation of stellar BHs does not lead to a long-term physical separation of most BHs into a dynamically decoupled inner core, as often assumed previously. Combined with the recent detections of several BH X-ray binary candidates in Galactic GCs, our results suggest that stellar BHs could still be present in large numbers in many GCs today, and that they may play a significant role in shaping the long-term dynamical evolution and the present-day dynamical structure of many clusters.« less

Double cusp encounter by Cluster: double cusp or motion of the cusp?

NASA Astrophysics Data System (ADS)

Escoubet, C. P.; Berchem, J.; Trattner, K. J.; Pitout, F.; Richard, R.; Taylor, M. G. G. T.; Soucek, J.; Grison, B.; Laakso, H.; Masson, A.; Dunlop, M.; Dandouras, I.; Reme, H.; Fazakerley, A.; Daly, P.

2013-04-01

Modelling plasma entry in the polar cusp has been successful in reproducing ion dispersions observed in the cusp at low and mid-altitudes. The use of a realistic convection pattern, when the IMF-By is large and stable, allowed Wing et al. (2001) to predict double cusp signatures that were subsequently observed by the DMSP spacecraft. In this paper we present a cusp crossing where two cusp populations are observed, separated by a gap around 1° Invariant Latitude (ILAT) wide. Cluster 1 (C1) and Cluster 2 (C2) observed these two cusp populations with a time delay of 3 min, and about 15 and 42 min later Cluster 4 (C4) and Cluster 3 (C3) observed, respectively, a single cusp population. A peculiarity of this event is the fact that the second cusp population seen on C1 and C2 was observed at the same time as the first cusp population on C4. This would tend to suggest that the two cusp populations had spatial features similar to the double cusp. Due to the nested crossing of C1 and C2 through the gap between the two cusp populations, C2 being first to leave the cusp and last to re-enter it, these observations are difficult to be explained by two distinct cusps with a gap in between. However, since we observe the cusp in a narrow area of local time post-noon, a second cusp may have been present in the pre-noon sector but could not be observed. On the other hand, these observations are in agreement with a motion of the cusp first dawnward and then back duskward due to the effect of the IMF-By component.

Mapping the tidally disrupting Andromeda XXVII and its stellar stream

NASA Astrophysics Data System (ADS)

Preston, Janet; Collins, Michelle; Bonaca, Ana; Ibata, Rodrigo; Tollerud, Erik; Geha, Marla; PAndAS Collaboration

2017-03-01

Andromeda XXVII is a dwarf spheroidal galaxy in the outskirts of the Andromeda galaxy (M31). It appears to be dissolving in to the Northern arc of M31, and could be the remnant of a strong tidal disruption. In the upcoming months, our spectroscopic program, which has measured velocities for multiple stars within both the dwarf galaxy progenitor and its stream (using the Keck II DEIMOS telescope, as part of the PAndAS survey), will determine velocity dispersions, scale radii and metallicities of both the dwarf and the stream. This in turn may enable us to ascertain the progenitor mass profile and determine whether it is cusped or cored.

Cluster observations of two separated cusp populations: double cusp or motion of the cusp?

NASA Astrophysics Data System (ADS)

Escoubet, C.-Philippe; Berchem, Jean; Trattner, Karlheinz; Pitout, Frederic; Richard, Robert; Taylor, Matt; Soucek, Jan; Grison, Benjamin; Laakso, Harri; Masson, Arnaud; Dunlop, Malcolm; Dandouras, Iannis; Reme, Henri; Fazakerley, Andrew; Daly, Patrick

2013-04-01

Modelling plasma entry in the polar cusp has been successful in reproducing ion dispersions observed in the cusp at low and mid-altitudes. The use of a realistic convection pattern allowed Wing et al. (2001) to predict double cusp signatures that were subsequently observed by the DMSP spacecraft. In this paper, we present a cusp crossing where two cusp populations are observed, separated by a gap around 1° ILAT wide. Cluster 1 (C1) and Cluster 2 (C2) observed these two cusp populations with a time delay of three minutes and about 15 and 42 minutes later, Cluster 4 (C4) and Cluster 3 (C3) observed, respectively, a single cusp population. A peculiarity of this event is the fact that the second cusp population seen on C1 and C2 was observed at the same time as the first cusp population on C4. This would tend to suggest that the two cusp populations were spatial features similar to the double cusp. Due to the nested crossing of C1 and C2 through the gap between the two cusp encounters, C2 being first to leave the cusp and last to re-enter it, these observations cannot be explained by two stable cusps with a gap of precipitation in between. On the other hand these observations are in agreement with a motion of the cusp first dawnward and then back duskward due to the effect of the IMF-By component.

On the Relation Between Soft Electron Precipitations in the Cusp Region and Solar Wind Coupling Functions

NASA Astrophysics Data System (ADS)

Dang, Tong; Zhang, Binzheng; Wiltberge, Michael; Wang, Wenbin; Varney, Roger; Dou, Xiankang; Wan, Weixing; Lei, Jiuhou

2018-01-01

In this study, the correlations between the fluxes of precipitating soft electrons in the cusp region and solar wind coupling functions are investigated utilizing the Lyon-Fedder-Mobarry global magnetosphere model simulations. We conduct two simulation runs during periods from 20 March 2008 to 16 April 2008 and from 15 to 24 December 2014, which are referred as "Equinox Case" and "Solstice Case," respectively. The simulation results of Equinox Case show that the plasma number density in the high-latitude cusp region scales well with the solar wind number density (ncusp/nsw=0.78), which agrees well with the statistical results from the Polar spacecraft measurements. For the Solstice Case, the plasma number density of high-latitude cusp in both hemispheres increases approximately linearly with upstream solar wind number density with prominent hemispheric asymmetry. Due to the dipole tilt effect, the average number density ratio ncusp/nsw in the Southern (summer) Hemisphere is nearly 3 times that in the Northern (winter) Hemisphere. In addition to the solar wind number density, 20 solar wind coupling functions are tested for the linear correlation with the fluxes of precipitating cusp soft electrons. The statistical results indicate that the solar wind dynamic pressure p exhibits the highest linear correlation with the cusp electron fluxes for both equinox and solstice conditions, with correlation coefficients greater than 0.75. The linear regression relations for equinox and solstice cases may provide an empirical calculation for the fluxes of cusp soft electron precipitation based on the upstream solar wind driving conditions.

Double cusp encounter by Cluster: double cusp or motion of the cusp?

NASA Astrophysics Data System (ADS)

Escoubet, C. P.; Berchem, J.; Trattner, K. J.; Pitout, F.; Richard, R. L.; Taylor, M. G.; Soucek, J.; Grison, B.; Laakso, H. E.; Masson, A.; Dunlop, M. W.; Dandouras, I. S.; Reme, H.; Fazakerley, A. N.; Daly, P. W.

2012-12-01

Modeling plasma entry in the polar cusp has been successful in reproducing ion dispersions observed in the cusp at low and mid-altitudes. The use of a realistic convection pattern allowed Wing et al. [2001] to model double cusp signatures that were observed by the DMSP spacecraft when the Interplanetary Magnetic Field (IMF) is southward but has a dominant By component (|IMF-By|>|IMF-Bz|). Under these conditions, reconnection between the IMF and the geomagnetic field is predicted to occur both at high latitudes and around the equatorial plane (or subsolar region). This multiple reconnection topology subsequently produces two different injections of plasma into the cusp, hence the observation of the so-called double cusp. However, the two cusps can be very close to each other and a detailed analysis of the dispersion of the precipitating ions is very often required to clearly identify them. We will present a cusp crossing where two cusps are observed, separated by 1° ILAT. Cluster 1 and 2 observed these two cusps within a few minute interval and about 10 and 50 min later, respectively, Cluster 4 and 3 observed a single cusp only. A peculiarity of this event was the fact that the second cusp seen on C1 and C2 was observed at the same time as the first cusp on C4. This would tend to suggest that the two dispersions are spatial features similar to the double cusp. However more detailed analysis of the characteristics of the cusps (ion dispersion, boundaries) and the IMF abrupt changes clearly showed that the double cusp was in fact a single cusp that had moved toward dawn and then back toward dusk following the changes in the IMF direction.

Mechanical constraint from growing jaw facilitates mammalian dental diversity

PubMed Central

Renvoisé, Elodie; Kavanagh, Kathryn D.; Lazzari, Vincent; Häkkinen, Teemu J.; Rice, Ritva; Pantalacci, Sophie; Salazar-Ciudad, Isaac; Jernvall, Jukka

2017-01-01

Much of the basic information about individual organ development comes from studies using model species. Whereas conservation of gene regulatory networks across higher taxa supports generalizations made from a limited number of species, generality of mechanistic inferences remains to be tested in tissue culture systems. Here, using mammalian tooth explants cultured in isolation, we investigate self-regulation of patterning by comparing developing molars of the mouse, the model species of mammalian research, and the bank vole. A distinct patterning difference between the vole and the mouse molars is the alternate cusp offset present in the vole. Analyses of both species using 3D reconstructions of developing molars and jaws, computational modeling of cusp patterning, and tooth explants cultured with small braces show that correct cusp offset requires constraints on the lateral expansion of the developing tooth. Vole molars cultured without the braces lose their cusp offset, and mouse molars cultured with the braces develop a cusp offset. Our results suggest that cusp offset, which changes frequently in mammalian evolution, is more dependent on the 3D support of the developing jaw than other aspects of tooth shape. This jaw–tooth integration of a specific aspect of the tooth phenotype indicates that organs may outsource specific aspects of their morphology to be regulated by adjacent body parts or organs. Comparative studies of morphologically different species are needed to infer the principles of organogenesis. PMID:28808032

Model of Tooth Morphogenesis Predicts Carabelli Cusp Expression, Size, and Symmetry in Humans

PubMed Central

Hunter, John P.; Guatelli-Steinberg, Debbie; Weston, Theresia C.; Durner, Ryan; Betsinger, Tracy K.

2010-01-01

Background The patterning cascade model of tooth morphogenesis accounts for shape development through the interaction of a small number of genes. In the model, gene expression both directs development and is controlled by the shape of developing teeth. Enamel knots (zones of nonproliferating epithelium) mark the future sites of cusps. In order to form, a new enamel knot must escape the inhibitory fields surrounding other enamel knots before crown components become spatially fixed as morphogenesis ceases. Because cusp location on a fully formed tooth reflects enamel knot placement and tooth size is limited by the cessation of morphogenesis, the model predicts that cusp expression varies with intercusp spacing relative to tooth size. Although previous studies in humans have supported the model's implications, here we directly test the model's predictions for the expression, size, and symmetry of Carabelli cusp, a variation present in many human populations. Methodology/Principal Findings In a dental cast sample of upper first molars (M1s) (187 rights, 189 lefts, and 185 antimeric pairs), we measured tooth area and intercusp distances with a Hirox digital microscope. We assessed Carabelli expression quantitatively as an area in a subsample and qualitatively using two typological schemes in the full sample. As predicted, low relative intercusp distance is associated with Carabelli expression in both right and left samples using either qualitative or quantitative measures. Furthermore, asymmetry in Carabelli area is associated with asymmetry in relative intercusp spacing. Conclusions/Significance These findings support the model's predictions for Carabelli cusp expression both across and within individuals. By comparing right-left pairs of the same individual, our data show that small variations in developmental timing or spacing of enamel knots can influence cusp pattern independently of genotype. Our findings suggest that during evolution new cusps may first appear as a result of small changes in the spacing of enamel knots relative to crown size. PMID:20689576

Selective Angiography Using the Radiofrequency Catheter: An Alternative Technique for Mapping and Ablation in the Aortic Cusps.

PubMed

Roca-Luque, Ivo; Rivas, Nuria; Francisco, Jaume; Perez, Jordi; Acosta, Gabriel; Oristrell, Gerard; Terricabres, Maria; Garcia-Dorado, David; Moya, Angel

2017-01-01

Ablation in aortic cusps could be necessary in up to 15% of the patients, especially in para-Hisian atrial tachycardia and ventricular arrhythmias arising from outflow tracts. Risk of coronary damage has led to recommendation of systematic coronary angiography (CA) during the procedure. Other image tests as intravascular (ICE) or transesophageal echocardiography (TEE) have been proposed. Both methods have limitations: additional vascular access for ICE and need for additional CA in some patients in case of TEE. We describe an alternative method to assess relation of catheter tip and coronary ostia during ablation in aortic cusps without additional vascular accesses by performing selective angiography with the ablation catheter. We prospectively evaluated 12 consecutive patients (69.3 ± 8.5, 6 female) who underwent ablation in right (1), left (5), and noncoronary cusps (6). We performed angiography through the ablation cooled tip radiofrequency catheter at the ablation site. Ablation was effective in 91.6% of the patients (3 patients needed additional ablation out of coronary cusps: pulmonary cusp, right ventricular outflow tract (RVOT), and coronary sinus and 1 patient underwent a second procedure because recurrence). No complications occurred neither during procedure nor follow-up (6.2 ± 3.8 months). No technical problems occurred with the ablation catheter after contrast injection. Selective angiography through a cooled-tip radiofrequency ablation catheter is feasible to assess relation of coronary ostia and ablation site when ablation in aortic cusps. It allows continuous real-time assessment of this relation, avoids the need for additional vascular accesses and no complications occurred in our series. © 2016 Wiley Periodicals, Inc.

Planar biaxial testing of heart valve cusp replacement biomaterials: Experiments, theory and material constants.

PubMed

Labrosse, Michel R; Jafar, Reza; Ngu, Janet; Boodhwani, Munir

2016-11-01

Aortic valve (AV) repair has become an attractive option to correct aortic insufficiency. Yet, cusp reconstruction with various cusp replacement materials has been associated with greater long-term repair failures, and it is still unknown how such materials mechanically compare with native leaflets. We used planar biaxial testing to characterize six clinically relevant cusp replacement materials, along with native porcine AV leaflets, to ascertain which materials would be best suited for valve repair. We tested at least six samples of: 1) fresh autologous porcine pericardium (APP), 2) glutaraldehyde fixed porcine pericardium (GPP), 3) St Jude Medical pericardial patch (SJM), 4) CardioCel patch (CC), 5) PeriGuard (PG), 6) Supple PeriGuard (SPG) and 7) fresh porcine AV leaflets (PC). We introduced efficient displacement-controlled testing protocols and processing, as well as advanced convexity requirements on the strain energy functions used to describe the mechanical response of the materials under loading. The proposed experimental and data processing pipeline allowed for a robust in-plane characterization of all the materials tested, with constants determined for two Fung-like hyperelastic, anisotropic strain energy models. Overall, CC and SPG (respectively PG) patches ranked as the closest mechanical equivalents to young (respectively aged) AV leaflets. Because the native leaflets as well as CC, PG and SPG patches exhibit significant anisotropic behaviors, it is suggested that the fiber and cross-fiber directions of these replacement biomaterials be matched with those of the host AV leaflets. The long-term performance of cusp replacement materials would ideally be evaluated in large animal models for AV disease and cusp repair, and over several months or more. Given the unavailability and impracticality of such models, detailed information on stress-strain behavior, as studied herein, and investigations of durability and valve dynamics will be the best surrogates, as they have been for prosthetic valves. Overall, comparison with Fig. 3 suggests that CC and SPG (respectively PG) patches may be the closest mechanical equivalents to young (respectively aged) AV leaflets. Interestingly, the thicknesses of these materials are close to those reported for porcine and younger human AV leaflets, which may facilitate surgical implantation, by contrast to the thinner APP which has poor handling qualities. Because the native leaflets as well as CC, PG and SPG patches exhibit anisotropic behaviors, from a mechanistic perspective alone, it stands to reason that cardiac surgeons should seek to intraoperatively match the fiber and cross-fiber directions of these replacement biomaterials with those of the repaired AV leaflets. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Internal Plasma Properties and Enhanced Performance of an 8 cm Ion Thruster Discharge

NASA Technical Reports Server (NTRS)

Foster, John E.; Patterson, Michael J.

1999-01-01

There is a need for a lightweight, low power ion thruster for space science missions. Such an ion thruster is under development at NASA Glenn Research Center. In an effort to better understand the discharge performance of this thruster. a version of this thruster with an anode containing electrically isolated electrodes at the cusps was fabricated and tested. Discharge characteristics of this ring cusp ion thruster were measured without ion beam extraction. Discharge current was measured at collection electrodes located at the cusps and at the anode body itself. Discharge performance and plasma properties were measured as a function of discharge power, which was varied between 20 and 50 W. It was found that ion production costs decreased by as much as 20 percent when the two most downstream cusp electrodes were allowed to float. Floating the electrodes did not give rise to a significant increase in discharge power even though the plasma density increased markedly. The improved performance is attributed to enhanced electron containment.

The functional significance of morphological changes in the dentitions of early mammals.

PubMed

Conith, Andrew J; Imburgia, Michael J; Crosby, Alfred J; Dumont, Elizabeth R

2016-11-01

The Mesozoic marked a time of experimentation in the tooth morphology of early mammals. One particular experiment involved the movement of three points, or cusps, on the surface of a molar tooth from a line into a triangle. This transition is exemplified by two extinct insectivorous mammals, Morganucodon (cusps in a line) and Kuehneotherium (cusps in a triangle). Here we test whether this difference in cusp arrangement, alongside cusp heights and angles between cusps, is associated with differences in the ability of the teeth to fracture proxy-insect prey. We gathered measurements from molar teeth of both species and used them to create physical models. We then measured the force, time and energy at fracture and peak force, and the amount of damage inflicted by the models on hard and soft gels encased in a tough film that mimicked the material properties of insects. The Morganucodon model required less force and energy to fracture hard gels and reach peak force compared with Kuehneotherium Kuehneotherium required a similar time, force and energy to fracture soft gels but reduced the time, force and energy to reach peak force. More importantly, Kuehneotherium also inflicted more damage to both the hard and the soft gels. These results suggest that changes in dental morphology in some early mammals was driven primarily by selection for maximizing damage, and secondarily for maximizing biomechanical efficiency for a given food material property. © 2016 The Author(s).

Effects of cusped field thruster on the performance of drag-free control system

NASA Astrophysics Data System (ADS)

Cui, K.; Liu, H.; Jiang, W. J.; Sun, Q. Q.; Hu, P.; Yu, D. R.

2018-03-01

With increased measurement tasks of space science, more requirements for the spacecraft environment have been put forward. Those tasks (e.g. the measurement of Earth's steady state gravity field anomalies) lead to the desire for developing drag-free control. Higher requirements for the thruster performance are made due to the demand for the drag-free control system and real-time compensation for non-conservative forces. Those requirements for the propulsion system include wide continuous throttling ability, high resolution, rapid response, low noise and so on. As a promising candidate, the cusped field thruster has features such as the high working stability, the low erosion rate, a long lifetime and the simple structure, so that it is chosen as the thruster to be discussed in this paper. Firstly, the performance of a new cusped field thruster is tested and analyzed. Then a drag-free control scheme based on the cusped field thruster is designed to evaluate the performance of this thruster. Subsequently, the effects of the thrust resolution, transient response time and thrust uncertainty on the controller are calculated respectively. Finally, the performance of closed-loop system is analyzed, and the simulation results verify the feasibility of applying cusped field thruster to drag-free flight in the space science measurement tasks.

Long-term Variability of Beach Cusps

NASA Astrophysics Data System (ADS)

Pianca, C.; Holman, R. A.; Siegle, E.

2016-02-01

The most curious morphological features observed on beaches are the cusps. Due to their rhythmic spacing, beach cusps have attracted many observers and many, often contradictory, theories as to their form. Moreover, most of the research about beach cusps has focused on their formation. Few had available long time series to study such things as the variability of alongshore and cross-shore position and spacing on the cusp field, the presence, longevity and interactions between higher and lower sets of cusps, and the processes by which cusp fields extend, shrink or change length scale. The purpose of this work is to use long-term data sets of video images from two study sites, an intermediate (Duck, USA, 26 years) and a reflective beach (Massaguaçu, Brazil, 3 years), to investigate the temporal and spatial changes of cusps conditions. Time-evolving shoreline data were first extracted using an algorithm called ASLIM (Pianca et al 2015). Cusps were then identified based on the band-passed variability of time exposure image data about this shoreline as a function of elevation relative to MSL. The identified beaches cusps will be analyzed for cusp spacing, positions (upper or lower cusps), alongshore variability, merging events, percentage of cusp events, patterns of the events and time scales of variability. Finally, the relationship of these characteristics to environmental conditions (wave, tides, beach conditions) will be studied.

Biomaterial Characterization of Off-the-Shelf Decellularized Porcine Pericardial Tissue for use in Prosthetic Valvular Applications.

PubMed

Choe, Joshua A; Jana, Soumen; Tefft, Brandon J; Hennessy, Ryan S; Go, Jason; Morse, David; Lerman, Amir; Young, Melissa D

2018-05-10

Fixed pericardial tissue is commonly used for commercially available xenograft valve implants, and has proven durability, but lacks the capability to remodel and grow. Decellularized porcine pericardial tissue has the promise to outperform fixed tissue and remodel, but the decellularization process has been shown to damage the collagen structure and reduce mechanical integrity of the tissue. Therefore, a comparison of uniaxial tensile properties was performed on decellularized, decellularized-sterilized, fixed, and native porcine pericardial tissue, versus native valve leaflet cusps. The results of non-parametric analysis showed statistically significant differences (p<0.05) between the stiffness of 1) decellularized vs. native pericardium, and native cusps as well as fixed tissue respectively; however decellularized tissue showed large increases in elastic properties. Porosity testing of the tissues showed no statistical difference between decellularized or decell-sterilized tissue compared to native cusps (p>0.05). SEM confirmed that valvular endothelial and interstitial cells colonized the decellularized pericardial surface when seeded and grown for 30 days in static culture. Collagen assays and TEM analysis showed limited reductions in collagen with processing; yet, GAG assays showed great reductions in the processed pericardium relative to native cusps. Decellularized pericardium had comparatively lower mechanical properties amongst the groups studied; yet, the stiffness was comparatively similar to the native cusps and demonstrated a lack of cytotoxicity. Suture retention, accelerated wear, and hydrodynamic testing of prototype decellularized and decell-sterilized valves showed positive functionality. Sterilized tissue could mimic valvular mechanical environment in vitro, therefore making it a viable potential candidate for off-the-shelf tissue engineered valvular applications. KEYTERMS Decellularization, Sterilization, Pericardial Tissue, Heart Valves, Tissue Engineering, Biomechanics. This article is protected by copyright. All rights reserved.

Understanding the structural features of symptomatic calcific aortic valve stenosis: A broad-spectrum clinico-pathologic study in 236 consecutive surgical cases.

PubMed

Galli, Daniela; Manuguerra, Roberta; Monaco, Rodolfo; Manotti, Laura; Goldoni, Matteo; Becchi, Gabriella; Carubbi, Cecilia; Vignali, Giulia; Cucurachi, Nicola; Gherli, Tiziano; Nicolini, Francesco; Lorusso, Roberto; Vitale, Marco; Corradi, Domenico

2017-02-01

With age, aortic valve cusps undergo varying degrees of sclerosis which, sometimes, can progress to calcific aortic valve stenosis (AVS). To perform a retrospective clinico-pathologic investigation in patients with calcific AVS. We characterized and graded the structural remodeling in 236 aortic valves (200 tricuspid and 36 bicuspid) from patients with calcific AVS (148 males; average 72years); possible relationships between general/clinical/echocardiographic characteristics and the histopathologic changes were explored. Twenty autopsy aortic valves served as controls. In 40 cases, we also tested the immunohistochemical expression of metalloproteinases and cytokines, and characterized the inflammatory infiltrate. In 5 cases, we cultured cusp stem cells and explored their potential to differentiate into osteoblasts/adipocytes. AVS cusps showed structural remodeling as severe fibrosis (100%), calcific nodules (100%), neoangiogenesis (81%), inflammation (71%), bone metaplasia with or without hematopoiesis (6% and 53%, respectively), adipose metaplasia (16%), and cartilaginous metaplasia (7%). At multivariate analysis, AVS degree and interventricular septum thickness were the only predictors of remodeling (barring inflammation). All the tested metalloproteinases (except MMP-13) and cytokines were expressed in AVS cusps. Inflammation mainly consisted of B and T lymphocytes (CD4+/CD8+ cell ratio 3:1) and plasma cells. AVS changes were mostly different from typical atherosclerosis. Cultured mesenchymal cusp stem cells could differentiate into osteoblasts/adipocytes. Structural remodeling in AVS is peculiar and considerable, and is related to the severity of the disease. However, the different newly formed tissues-where "valvular interstitial cells" play a key role-and their well-known slow turnover suggest a reverse structural remodeling improbable. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Remote magnetic navigation to map and ablate left coronary cusp ventricular tachycardia.

PubMed

Burkhardt, J David; Saliba, Walid I; Schweikert, Robert A; Cummings, Jennifer; Natale, Andrea

2006-10-01

Premature ventricular contractions (PVCs) and ventricular tachycardia may arise from the coronary cusps. Navigation, mapping, and ablation in the coronary cusps can be challenging. Remote magnetic navigation may offer an alternative to conventional manually operated catheters. We report a case of left coronary cusp ventricular tachycardia ablation using remote magnetic navigation. Right ventricular outflow tract and coronary cusp mapping, and ablation of the left coronary cusp using a remote magnetic navigation and three-dimensional (3-D) mapping system was performed in a 28-year-old male with frequent, symptomatic PVCs and ventricular tachycardia. Successful ablation of left coronary cusp ventricular tachycardia was performed using remote magnetic navigation. Remote magnetic navigation may be used to map and ablate PVCs and ventricular tachycardia originating from the coronary cusps.

Study on an azimuthal line cusp ion source for the KSTAR neutral beam injector.

PubMed

Jeong, Seung Ho; Chang, Doo-Hee; In, Sang Ryul; Lee, Kwang Won; Oh, Byung-Hoon; Yoon, Byung-Joo; Song, Woo Sob; Kim, Jinchoon; Kim, Tae Seong

2008-02-01

In this study it is found that the cusp magnetic field configuration of an anode bucket influences the primary electron behavior. An electron orbit code (ELEORBIT code) showed that an azimuthal line cusp (cusp lines run azimuthally with respect to the beam extraction direction) provides a longer primary electron confinement time than an axial line cusp configuration. Experimentally higher plasma densities were obtained under the same arc power when the azimuthal cusp chamber was used. The newly designed azimuthal cusp bucket has been investigated in an effort to increase the plasma density in its plasma generator per arc power.

Dark Matter Profiles in Dwarf Galaxies: A Statistical Sample Using High-Resolution Hα Velocity Fields from PCWI

NASA Astrophysics Data System (ADS)

Relatores, Nicole C.; Newman, Andrew B.; Simon, Joshua D.; Ellis, Richard; Truong, Phuongmai N.; Blitz, Leo

2018-01-01

We present high quality Hα velocity fields for a sample of nearby dwarf galaxies (log M/M⊙ = 8.4-9.8) obtained as part of the Dark Matter in Dwarf Galaxies survey. The purpose of the survey is to investigate the cusp-core discrepancy by quantifying the variation of the inner slope of the dark matter distributions of 26 dwarf galaxies, which were selected as likely to have regular kinematics. The data were obtained with the Palomar Cosmic Web Imager, located on the Hale 5m telescope. We extract rotation curves from the velocity fields and use optical and infrared photometry to model the stellar mass distribution. We model the total mass distribution as the sum of a generalized Navarro-Frenk-White dark matter halo along with the stellar and gaseous components. We present the distribution of inner dark matter density profile slopes derived from this analysis. For a subset of galaxies, we compare our results to an independent analysis based on CO observations. In future work, we will compare the scatter in inner density slopes, as well as their correlations with galaxy properties, to theoretical predictions for dark matter core creation via supernovae feedback.

Evolutionary patterns in the dentition of duplicidentata (mammalia) and a novel trend in the molarization of premolars.

PubMed

Kraatz, Brian P; Meng, Jin; Weksler, Marcelo; Li, Chuankui

2010-09-20

The cusp homology of Lagomorpha has long been problematic largely because their teeth are highly derived relative to their more typically tribosphenic ancestors. Within this context, the lagomorph central cusp has been particularly difficult to homologize with other tribosphenic cusps; authors have previously considered it the paracone, protocone, metacone, amphicone, or an entirely new cusp. Here we present newly described fossil duplicidentates (Lagomorpha and Mimotonidae) in the context of a well-constrained phylogeny to establish a nomenclatural system for cusps based on the tribosphenic pattern. We show that the central cusp of lagomorphs is homologous with the metaconule of other mammals. We also show that the buccal acquisition of a second cusp on the premolars (molarization) within duplicidentates is atypical with respect to other mammalian lineages; within the earliest lagomorphs, a second buccal cusp is added mesially to an isolated buccal cusp. The distal shift of the 'ancestral' paracone within early duplicidentates amounts to the changing of a paracone into a metacone in these lineages. For this reason, we support a strictly topological approach to cusp names, and suggest a discontinuity in nomenclature to capture the complexity of the interplay between evolutionary history and the developmental process that have produced cusp patterns in duplicidentates.

Evolutionary Patterns in the Dentition of Duplicidentata (Mammalia) and a Novel Trend in the Molarization of Premolars

PubMed Central

Kraatz, Brian P.; Meng, Jin; Weksler, Marcelo; Li, Chuankui

2010-01-01

Background The cusp homology of Lagomorpha has long been problematic largely because their teeth are highly derived relative to their more typically tribosphenic ancestors. Within this context, the lagomorph central cusp has been particularly difficult to homologize with other tribosphenic cusps; authors have previously considered it the paracone, protocone, metacone, amphicone, or an entirely new cusp. Methodology/Principal Findings Here we present newly described fossil duplicidentates (Lagomorpha and Mimotonidae) in the context of a well-constrained phylogeny to establish a nomenclatural system for cusps based on the tribosphenic pattern. We show that the central cusp of lagomorphs is homologous with the metaconule of other mammals. We also show that the buccal acquisition of a second cusp on the premolars (molarization) within duplicidentates is atypical with respect to other mammalian lineages; within the earliest lagomorphs, a second buccal cusp is added mesially to an isolated buccal cusp. Conclusions/Significance The distal shift of the ‘ancestral’ paracone within early duplicidentates amounts to the changing of a paracone into a metacone in these lineages. For this reason, we support a strictly topological approach to cusp names, and suggest a discontinuity in nomenclature to capture the complexity of the interplay between evolutionary history and the developmental process that have produced cusp patterns in duplicidentates. PMID:20877465

The Evolution of Dwarf Galaxy Satellites with Different Dark Matter Density Profiles in the ErisMod Simulations. I. The Early Infalls

NASA Astrophysics Data System (ADS)

Tomozeiu, Mihai; Mayer, Lucio; Quinn, Thomas

2016-02-01

We present the first simulations of tidal stirring of dwarf galaxies in the Local Group carried out in a fully cosmological context. We use the ErisDARK cosmological simulation of a Milky Way (MW)-sized galaxy to identify some of the most massive subhalos (Mvir > 108 M⊙) that fall into the main host before z = 2. Subhalos are replaced before infall with extremely high-resolution models of dwarf galaxies comprising a faint stellar disk embedded in a dark matter halo. The set of models contains cuspy halos as well as halos with “cored” profiles (with the cusp coefficient γ = 0.6) consistent with recent results of hydrodynamical simulations of dwarf galaxy formation. The simulations are then run to z = 0 with as many as 54 million particles and resolutions as small as ∼4 pc using the new parallel N-body code ChaNGa. The stellar components of all satellites are significantly affected by tidal stirring, losing stellar mass, and undergoing a morphological transformation toward a pressure supported spheroidal system. However, while some remnants with cuspy halos maintain significant rotational flattening and disk-like features, all the shallow halo models achieve vrot/σ⋆ < 0.5 and round shapes typical of dSph satellites of the MW and M31. Mass loss is also enhanced in the latter, and remnants can reach luminosities and velocity dispersions as low as those of ultra-faint dwarfs.

The center of the core-cusp globular cluster M15: CFHT and HST Observations, ALLFRAME reductions

NASA Astrophysics Data System (ADS)

Stetson, Peter B.

1994-03-01

The central brightness cusps seen in some globular clusters are thought to be the relics of a gravothermal core collapse that occurred sometime in the clusters' past. Recent observations show that the centers of such clusters are bluer than their outskirts, indicating that the stellar populations there are somehow different than those farther out, presumably as a result of unusual physical processes that took place in these extremely dense regions. Here I analyze a large body of digital imagery from the Canada-France-Hawaii Telescope and the Hubble Space Telescope to obtain color-magnitude and color-color diagrams for stars in the central two arcminutes of the prototypical core-cusp globular cluster M15 = NGC 7078 = C 2127 + 119. These data were reduced with a new computer program, named ALLFRAME, that is described in detail here for the first time. ALLFRAME makes simultaneous use of the geometric and photometric information from all images of a given field to derive a self-consistent set of positions and magnitudes for all detected starlike objects in that area of sky, thereby extending the range of magnitude and crowding conditions for which useful photometry is obtainable. I tentatively conclude that the color gradient in M15 is due to three distinct effects: (1) there is a deficiency of the brightest red giants in the central regions of the cluster; (2) the giant branch of the dominant cluster population shifts systematically toward the blue as the center of the cluster is approached; and (3) the very center of the cluster (radius approximately equal or less than 12 seconds) contains a large population of blue and yellow stragglers that occupy the area of the color-magnitude diagram between the main-sequence turnoff and the horizontal branch and between the extended blue horizontal branch and the subgiant branch; many of these appear to have a significant ultraviolet excess.

The polar cusp: Cluster observations and simulations

NASA Astrophysics Data System (ADS)

Escoubet, C. Philippe; Berchem, Jean; Pitout, Frederic; Richard, Robert; Trattner, Karlheinz; Grison, Benjamin; Taylor, Matthew; Laakso, Harri; Masson, Arnaud; Dunlop, Malcolm; Dandouras, Iannis; Reme, Henri; Fazakerley, Andrew N.

The polar cusp, together with the magnetopause, are the magnetospheric regions in direct contact with the shocked solar wind flowing continuously from the Sun. Therefore any changes in the solar wind plasma reaching the magnetopause induce changes in the polar cusp with a delay of a few minutes to a few tens of minutes. For instance a change of the interplanetary magnetic field (IMF) direction from South to North will displace the polar cusp poleward and at the same time will change the injection of ions from the subsolar magnetopause to the magnetotail lobes. In the mid and low-altitude cusp a spacecraft will then observe a reversal of the dispersion in energy of the ions. We will use Cluster string of pearl configuration in the mid-altitude polar cusp to investigate the temporal variations of ion injections in the polar cusp. In the period from July to September, the Cluster spacecraft follow each other in the mid-altitude cusp with a delay of few minutes up to one hour. A few examples of cusp crossings will be presented to illustrate the influence of solar wind changes in the polar cusp. We will show that a sudden change in the IMF direction from South to North produces a double cusp crossing. By opposition, a change of the IMF from North to South produces a temporal injection on the equatorward side of the cusp and an erosion of the magnetosphere. Finally, we will show that when the interplanetary conditions are stable with the IMF pointing Northward or Southward for more than 10 min the polar cusp ion dispersion stays constant. MHD and large-scale particle simulations will also be used to complement the Cluster data.

Protection motivation theory and cigarette smoking among vocational high school students in China: a cusp catastrophe modeling analysis.

PubMed

Xu, Yunan; Chen, Xinguang

2016-01-01

Tobacco use is one of the greatest public health problems worldwide and the hazards of cigarette smoking to public health call for better recognition of cigarette smoking behaviors to guide evidence-based policy. Protection motivation theory (PMT) provides a conceptual framework to investigate tobacco use. Evidence from diverse sources implies that the dynamics of smoking behavior may be quantum in nature, consisting of an intuition and an analytical process, challenging the traditional linear continuous analytical approach. In this study, we used cusp catastrophe, a nonlinear analytical approach to test the dual-process hypothesis of cigarette smoking. Data were collected from a random sample of vocational high school students in China ( n = 528). The multivariate stochastic cusp modeling was used and executed with the Cusp Package in R. The PMT-based Threat Appraisal and Coping Appraisal were used as the two control variables and the frequency of cigarette smoking (daily, weekly, occasional, and never) in the past month was used as the outcome variable. Consistent with PMT, the Threat Appraisal (asymmetry, α 1 = 0.1987, p < 0.001) and Coping Appraisal (bifurcation, β 2 = 0.1760, p < 0.05) significantly predicted the smoking behavior after controlling for covariates. Furthermore, the cusp model performed better than the alternative linear and logistic regression models with regard to higher R 2 (0.82 for cusp, but 0.21 for linear and 0.25 for logistic) and smaller AIC and BIC. Study findings support the conclusion that cigarette smoking in adolescents is a quantum process and PMT is relevant to guide studies to understand smoking behavior for smoking prevention and cessation.

Frequency and variability of dental morphology in deciduous and permanent dentition of a Nasa indigenous group in the municipality of Morales, Cauca, Colombia.

PubMed

Díaz, Eider; García, Lorena; Hernández, Michelle; Palacio, Lesly; Ruiz, Diana; Velandia, Nataly; Villavicencio, Judy; Moreno, Freddy

2014-01-01

To determine the frequency, variability, sexual dimorphism and bilateral symmetry of fourteen dental crown traits in the deciduous and permanent dentition of 60 dental models (35 women and 25 men) obtained from a native, indigenous group of Nasa school children of the Musse Ukue group in the municipality of Morales, Department of Cauca, Colombia. This is a quantitative, descriptive, cross-sectional study that characterizes dental morphology by means of the systems for temporary dentition from Dahlberg (winging), and ASUDAS (crowding, reduction of hypocone, metaconule and cusp 6), Hanihara (central and lateral incisors in shovel-shape and cusp 7), Sciulli (double bit, layered fold protostylid, cusp pattern and cusp number) and Grine (Carabelli trait); and in permanent dentition from ASUDAS (Winging, crowding, central and lateral incisors in shovel-shape and double shovel-shape, Carabelli trait, hypocone reduction, metaconule, cusp pattern, cusp number, layered fold protostylid, cusp 6 and cusp 7). The most frequent dental crown features were the shovel-shaped form, grooved and fossa forms of the Carabelli trait, metaconule, cusp pattern Y6, layered fold, protostylid (point P) and cusp 6. Sexual dimorphism was not observed and there was bilateral symmetry in the expression of these features. The sample studied presented a great affinity with ethnic groups belonging to the Mongoloid Dental Complex due to the frequency (expression) and variability (gradation) of the tooth crown traits, upper incisors, the Carabelli trait, the protostylid, cusp 6 and cusp 7. The influence of the Caucasoide Dental Complex associated with ethno-historical processes cannot be ruled out.

Cusp conditions for two electrons atoms in the Hylleraas aproximation

NASA Astrophysics Data System (ADS)

Carvalho, F. S.; Braga, J. P.

2018-07-01

In this work it was shown how cusp conditions in radial coordinates are implied in the fundamental idea of the R12 method used in electronic structure calculations. We also derived the cusp conditions in Hylleraas coordinates through Hamiltonian singularities analysis. The functions described in literature which depend on these variables were investigated and it was found that these functions do not necessarily satisfy the cusp conditions, although they return good energy results with few parameters. Starting from the cusp conditions derived in the Hylleraas coordinates, three restrictions were established for the wavefunctions. An example of this correct cusp behavior for a particular wavefunctions is given. This issue is of great importance since the cusp conditions guarantee a better convergence for numerical results.

How wide in magnetic local time is the cusp? An event study

NASA Astrophysics Data System (ADS)

Maynard, N. C.; Weber, E. J.; Weimer, D. R.; Moen, J.; Onsager, T.; Heelis, R. A.; Egeland, A.

1997-03-01

A unique pass of the DMSP F11 satellite, longitudinally cutting through the cusp and mantle, combined with simultaneous optical measurements of the dayside cusp from Svalbard has been used to determine the width in local time of the cusp. We have shown from this event study that the cusp was at least 3.7 hours wide in magnetic local time. These measurements provide a lower limit for the cusp width. The observed cusp optical emissions are relatively constant, considering the processes which lead to the 630.0 nm emissions, and require precipitating electron flux to be added each minute during the DMSP pass throughout the local time extent observed by the imaging photometer and probably over the whole extent of the cusp defined by DMSP data. We conclude that the electron fluxes which produce the cusp aurora are from a process which must have been operable sometime during each minute but could have had both temporal and spatial variations. The measured width along with models of cusp precipitation provide the rationale to conclude that the region of flux tube opening in the dayside merging process involves the whole frontside magnetopause and can extend beyond the dawn-dusk terminator. The merging process for this event was found to be continuous, although spatially and temporally variable.

Localized Models of Charged Particle Motion in Martian Crustal Magnetic Cusps

NASA Astrophysics Data System (ADS)

Brain, D. A.; Poppe, A. R.; Jarvinen, R.; Dong, Y.; Egan, H. L.; Fang, X.

2017-12-01

The induced magnetosphere of Mars is punctuated by localized but strong crustal magnetic fields that are observed to play host to a variety of phenomena typically associated with global magnetic fields, such as auroral processes and particle precipitation, field-aligned current systems, and ion outflow. Each of these phenomena occur on the night side, in small-scale magnetic `cusp' regions of vertically aligned field. Cusp regions are not yet capable of being spatially resolved in global scale models that include the ion kinetics necessary for simulating charged particle transport along cusps. Local models are therefore necessary if we are to understand how cusp processes operate at Mars. Here we present the first results of an effort to model the kinetic particle motion and electric fields in Martian cusps. We are adapting both a 1.5D Particle-in-Cell (PIC) model for lunar magnetic cusps regions to the Martian case and a hybrid model framework (used previously for the global Martian plasma interaction and for lunar magnetic anomaly regions) to cusps in 2D. By comparing the models we can asses the importance of electron kinetics in particle transport along cusp field lines. In this first stage of our study we model a moderately strong nightside cusp, with incident hot hydrogen plasma from above, and cold planetary (oxygen) plasma entering the simulation from below. We report on the spatial and temporal distribution of plasma along cusp field lines for this initial case.

Analysis of the curve of Spee and the curve of Wilson in adult Indian population: A three-dimensional measurement study.

PubMed

Surendran, Sowmya Velekkatt; Hussain, Sharmila; Bhoominthan, S; Nayar, Sanjna; Jayesh, Ragavendra

2016-01-01

When reconstructing the occlusal curvatures dentists often use a 4-inch radii arc as a rough standard based on Monson spherical theory. The use of an identical radius for the curve of Spee for all patients may not be appropriate because each patient is individually different. The validity of application of this theory in the Indian population and the present study has been undertaken. This study is an attempt to evaluate the curve of Spee and curve of Wilson in young Indian population using three dimensional analysis. This study compared the radius and the depth of right and left, maxillary and mandibular curves of Spee and the radius of maxillary and mandibular curves of Wilson in males and females. The cusp tips of canines, buccal cusp tips of premolars and molars and palatal/lingual cusp tips of second molars of 60 maxillary and 60 mandibular casts were obtained. Three-dimensional (x, y, z) coordinates of the cusp tips of the molars, premolars, and canines of the right and left sides of the maxilla and mandible were obtained with three dimensional coordinate measuring machine. The radius and the depth of right and left, maxillary and mandibular curves of Spee and the radius of maxillary and mandibular curves of Wilson were measured by means of computer software Metrologic-XG. Pearson's correlation test and Independent t-test were used to test the statistical significance (α=.05). The values of curve of Spee and curve of Wilson in Indian population obtained from this study were higher than the 4 inch (100 mm) radius proposed by Monson. These findings suggest ethnic differences in the radius of curve of Spee and curve of Wilson.

Frequency and variability of dental morphology in deciduous and permanent dentition of a Nasa indigenous group in the municipality of Morales, Cauca, Colombia

PubMed Central

Díaz, Eider; García, Lorena; Hernández, Michelle; Palacio, Lesly; Ruiz, Diana; Velandia, Nataly; Villavicencio, Judy

2014-01-01

Objectives: To determine the frequency, variability, sexual dimorphism and bilateral symmetry of fourteen dental crown traits in the deciduous and permanent dentition of 60 dental models (35 women and 25 men) obtained from a native, indigenous group of Nasa school children of the Musse Ukue group in the municipality of Morales, Department of Cauca, Colombia. Methods: This is a quantitative, descriptive, cross-sectional study that characterizes dental morphology by means of the systems for temporary dentition from Dahlberg (winging), and ASUDAS (crowding, reduction of hypocone, metaconule and cusp 6), Hanihara (central and lateral incisors in shovel-shape and cusp 7), Sciulli (double bit, layered fold protostylid, cusp pattern and cusp number) and Grine (Carabelli trait); and in permanent dentition from ASUDAS (Winging, crowding, central and lateral incisors in shovel-shape and double shovel-shape, Carabelli trait, hypocone reduction, metaconule, cusp pattern, cusp number, layered fold protostylid, cusp 6 and cusp 7). Results: The most frequent dental crown features were the shovel-shaped form, grooved and fossa forms of the Carabelli trait, metaconule, cusp pattern Y6, layered fold, protostylid (point P) and cusp 6. Sexual dimorphism was not observed and there was bilateral symmetry in the expression of these features. Conclusions: The sample studied presented a great affinity with ethnic groups belonging to the Mongoloid Dental Complex due to the frequency (expression) and variability (gradation) of the tooth crown traits, upper incisors, the Carabelli trait, the protostylid, cusp 6 and cusp 7. The influence of the Caucasoide Dental Complex associated with ethno-historical processes cannot be ruled out. PMID:24970955

Computational Study of Primary Electrons in the Cusp Region of an Ion Engine's Discharge Chamber

NASA Technical Reports Server (NTRS)

Stueber, Thomas J. (Technical Monitor); Deshpande, Shirin S.; Mahalingam, Sudhakar; Menart, James A.

2004-01-01

In this work a computer code called PRIMA is used to study the motion of primary electrons in the magnetic cusp region of the discharge chamber of an ion engine. Even though the amount of wall area covered by the cusps is very small, the cusp regions are important because prior computational analyses have indicated that most primary electrons leave the discharge chamber through the cusps. The analysis presented here focuses on the cusp region only. The affects of the shape and size of the cusp region on primary electron travel are studied as well as the angle and location at which the electron enters the cusp region. These affects are quantified using the confinement length and the number density distributions of the primary electrons. In addition to these results comparisons of the results from PRIMA are made to experimental results for a cylindrical discharge chamber with two magnetic rings. These comparisons indicate the validity of the computer code called PRIMA.

The acquisition of problem behavior in individuals with developmental disabilities as a behavioral cusp.

PubMed

Robertson, Rachel E

2015-07-01

A behavioral cusp has been defined as a behavior change that produces contact with new contingencies with important and far-reaching consequences. The concept of behavioral cusps has most frequently been used to select target skills taught to learners and to evaluate the importance of those skills; however, the concept is equally applicable to behavior changes that bring about important and far-reaching negative consequences. Although it has been acknowledged that socially undesirable behavior change can also qualify as a behavioral cusp, this area of the cusp concept has been under-examined. In this article, an undesirable behavior change, the acquisition of problem behavior in individuals with developmental disabilities, is compared with criteria for behavioral cusps previously identified in the literature. The advantages of viewing problem behavior as a behavioral cusp are outlined, and implications for practice and research from a behavioral cusp approach to problem behavior are provided. © The Author(s) 2015.

Anomalous dynamical phase in quantum spin chains with long-range interactions

NASA Astrophysics Data System (ADS)

Homrighausen, Ingo; Abeling, Nils O.; Zauner-Stauber, Valentin; Halimeh, Jad C.

2017-09-01

The existence or absence of nonanalytic cusps in the Loschmidt-echo return rate is traditionally employed to distinguish between a regular dynamical phase (regular cusps) and a trivial phase (no cusps) in quantum spin chains after a global quench. However, numerical evidence in a recent study (J. C. Halimeh and V. Zauner-Stauber, arXiv:1610.02019) suggests that instead of the trivial phase, a distinct anomalous dynamical phase characterized by a novel type of nonanalytic cusps occurs in the one-dimensional transverse-field Ising model when interactions are sufficiently long range. Using an analytic semiclassical approach and exact diagonalization, we show that this anomalous phase also arises in the fully connected case of infinite-range interactions, and we discuss its defining signature. Our results show that the transition from the regular to the anomalous dynamical phase coincides with Z2-symmetry breaking in the infinite-time limit, thereby showing a connection between two different concepts of dynamical criticality. Our work further expands the dynamical phase diagram of long-range interacting quantum spin chains, and can be tested experimentally in ion-trap setups and ultracold atoms in optical cavities, where interactions are inherently long range.

Cusps in the center of galaxies: a real conflict with observations or a numerical artefact of cosmological simulations?

NASA Astrophysics Data System (ADS)

Baushev, A. N.; del Valle, L.; Campusano, L. E.; Escala, A.; Muñoz, R. R.; Palma, G. A.

2017-05-01

Galaxy observations and N-body cosmological simulations produce conflicting dark matter halo density profiles for galaxy central regions. While simulations suggest a cuspy and universal density profile (UDP) of this region, the majority of observations favor variable profiles with a core in the center. In this paper, we investigate the convergency of standard N-body simulations, especially in the cusp region, following the approach proposed by [1]. We simulate the well known Hernquist model using the SPH code Gadget-3 and consider the full array of dynamical parameters of the particles. We find that, although the cuspy profile is stable, all integrals of motion characterizing individual particles suffer strong unphysical variations along the whole halo, revealing an effective interaction between the test bodies. This result casts doubts on the reliability of the velocity distribution function obtained in the simulations. Moreover, we find unphysical Fokker-Planck streams of particles in the cusp region. The same streams should appear in cosmological N-body simulations, being strong enough to change the shape of the cusp or even to create it. Our analysis, based on the Hernquist model and the standard SPH code, strongly suggests that the UDPs generally found by the cosmological N-body simulations may be a consequence of numerical effects. A much better understanding of the N-body simulation convergency is necessary before a `core-cusp problem' can properly be used to question the validity of the CDM model.

Cusps in the center of galaxies: a real conflict with observations or a numerical artefact of cosmological simulations?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baushev, A.N.; Valle, L. del; Campusano, L.E.

2017-05-01

Galaxy observations and N-body cosmological simulations produce conflicting dark matter halo density profiles for galaxy central regions. While simulations suggest a cuspy and universal density profile (UDP) of this region, the majority of observations favor variable profiles with a core in the center. In this paper, we investigate the convergency of standard N-body simulations, especially in the cusp region, following the approach proposed by [1]. We simulate the well known Hernquist model using the SPH code Gadget-3 and consider the full array of dynamical parameters of the particles. We find that, although the cuspy profile is stable, all integrals ofmore » motion characterizing individual particles suffer strong unphysical variations along the whole halo, revealing an effective interaction between the test bodies. This result casts doubts on the reliability of the velocity distribution function obtained in the simulations. Moreover, we find unphysical Fokker-Planck streams of particles in the cusp region. The same streams should appear in cosmological N-body simulations, being strong enough to change the shape of the cusp or even to create it. Our analysis, based on the Hernquist model and the standard SPH code, strongly suggests that the UDPs generally found by the cosmological N-body simulations may be a consequence of numerical effects. A much better understanding of the N-body simulation convergency is necessary before a 'core-cusp problem' can properly be used to question the validity of the CDM model.« less

Beach Cusps: Spatial distribution and time evolution at Massaguaçú beach (SP), Brazil

NASA Astrophysics Data System (ADS)

dos Santos, H. H.; Siegle, E.; Sousa, P. H.

2013-05-01

Beach cusps are crescentic morphological structures observed on the foreshore of beaches characterized by steep seaward protruding extensions, called cusp horns, and gently sloped landward extensions, called cusp embayments. Their formation depends on the grain size, beach slope, tidal range and incoming waves. Cusps are best developed on gravel or shingle beaches, small tidal range with a large slope for incoming waves generate a well-developed swash excursion. These structures are quickly responding to wave climate and tidal range, changing the position of the rhythmic features on the beach face. Beach cusps are favored by normal incoming waves, while oblique waves tend to wash these features out. This study aims to analyze the spatial distribution and temporal evolution of rhythmic features such as beach cusps in Massaguaçú embayment (Caraguatatuba, northern coast of São Paulo, Brazil). This embayment has an extension of 7.5 km with reflective beaches cusped mainly in its more exposed central portion. The data set for this study consists of a series of video images (Argus system), covering a stretch of the beach. Visible beach cusps were digitalized from these rectified images. Results obtained from the images were related to the wave climate, water level and the storm surges. Results show that the cusps on the upper portion of the foreshore were more regular and present than the cusps on the lower portion of the foreshore due to the tidal modulation of wave action. The cusp spacing on the upper portion of the foreshore is of about 38 m and the lower portion of the foreshore is of about 28 m and their presence was correlated with the wave direction and water elevation. As expected, waves approaching with shore-normal angles (southeast direction) were favorable to the formation of beach cusps while the waves from the southwest, south, east and northeast generated a longshore current that reduced or destroyed any rhythmic feature. Other important forcing was the influence of the water level. Waves acting at higher water levels are able to produce the less dynamic upper layer of cusps. During 31 consecutive days from 8 July 2011 to 8 August of the same year these features show four periods with the presence of cusps on the upper and lower portion of the foreshore with three periods with cups only on the upper portion of the foreshore. The analyzed dataset shows the highly dynamic behavior of cusps, with rapid generation and destruction, related directly to its forcing hydrodynamic conditions.

Cusp observations with Cluster and THEMIS in preparation for the SMILE mission

NASA Astrophysics Data System (ADS)

Escoubet, C.-Philippe

2017-04-01

Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a novel self-standing mission, being designed in collaboration between ESA and the Chinese Academy of Science. Its objective is to observe solar wind-magnetosphere coupling via simultaneous in situ solar wind/magnetosheath plasma and magnetic field measurements, soft X-Ray images of the magnetosheath and polar cusps, and UV images of global auroral distributions. The observations of the cusps and magnetosheath with the X-ray imager are possible thanks to the relatively recent discovery of solar wind charge exchange (SWCX) X-ray emissions, first at comets and subsequently in the vicinity of the Earth's magnetosphere. To prepare for the mission, we must determine the cusp's expected morphology, motion, and in situ properties (density, velocity, temperature). We have selected a series of Cluster cusp crossings that define these properties and can therefore be used to estimate X-ray emissions across the width of the cusp for different IMF orientations. We will show that the peak soft X-ray emissions occur near the centre of the cusp where ion densities maximize. We then show that the integral lines of sight emissions through the cusp are a factor of 2.4 times larger for IMF-Bz northward than for IMF-Bz southward. The mid-altitude cusp is a factor of 7 brighter than the exterior cusp.

Development of a compact filament-discharge multi-cusp H- ion source.

PubMed

Jia, XianLu; Zhang, TianJue; Zheng, Xia; Qin, JiuChang

2012-02-01

A 14 MeV medical cyclotron with the external ion source has been designed and is being constructed at China Institute of Atomic Energy. The H(-) ion will be accelerated by this machine and the proton beam will be extracted by carbon strippers in dual opposite direction. The compact multi-cusp H(-) ion source has been developed for the cyclotron. The 79.5 mm long ion source is 48 mm in diameter, which is consisting of a special shape filament, ten columns of permanent magnets providing a multi-cusp field, and a three-electrode extraction system. So far, the 3 mA∕25 keV H(-) beam with an emittance of 0.3 π mm mrad has been obtained from the ion source. The paper gives the design details and the beam test results. Further experimental study is under way and an extracted beam of 5 mA is expected.

A comparison of linear versus non-linear models of aversive self-awareness, dissociation, and non-suicidal self-injury among young adults.

PubMed

Armey, Michael F; Crowther, Janis H

2008-02-01

Research has identified a significant increase in both the incidence and prevalence of non-suicidal self-injury (NSSI). The present study sought to test both linear and non-linear cusp catastrophe models by using aversive self-awareness, which was operationalized as a composite of aversive self-relevant affect and cognitions, and dissociation as predictors of NSSI. The cusp catastrophe model evidenced a better fit to the data, accounting for 6 times the variance (66%) of a linear model (9%-10%). These results support models of NSSI implicating emotion regulation deficits and experiential avoidance in the occurrence of NSSI and provide preliminary support for the use of cusp catastrophe models to study certain types of low base rate psychopathology such as NSSI. These findings suggest novel approaches to prevention and treatment of NSSI as well.

Some low-altitude cusp dependencies on the interplanetary magnetic field

NASA Technical Reports Server (NTRS)

Newell, Patrick T.; Meng, CHING-I.; Sibeck, David G.; Lepping, Ronald

1989-01-01

The low-altitude cusp dependencies on the interplanetary magnetic field (IMF) were investigated using the algorithm of Newell and Meng (1988) to identify the cusp proper. The algorithm was applied to 12,569 high-latitude dayside passes of the DMSP F7 spacecraft, and the resulting cusp positioning data were correlated with the IMF. It was found that the cusp latitudinal position correlated reasonably well (0.70) with the Bz component when the IMF had a southward component. The correlation for the northward Bz component was only 0.18, suggestive of a half-wave rectifier effect. The ratio of cusp ion number flux precipitation for Bz southward to that for Bz northward was 1.75 + or - 0.12. The statistical local time widths of the cusp proper for the northward and the southward Bz components were found to be 2.1 h and 2.8 h, respectively.

21 CFR 872.3350 - Gold or stainless steel cusp.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gold or stainless steel cusp. 872.3350 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3350 Gold or stainless steel cusp. (a) Identification. A gold or stainless steel cusp is a prefabricated device made of austenitic alloys or alloys...

21 CFR 872.3350 - Gold or stainless steel cusp.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gold or stainless steel cusp. 872.3350 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3350 Gold or stainless steel cusp. (a) Identification. A gold or stainless steel cusp is a prefabricated device made of austenitic alloys or alloys...

21 CFR 872.3350 - Gold or stainless steel cusp.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gold or stainless steel cusp. 872.3350 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3350 Gold or stainless steel cusp. (a) Identification. A gold or stainless steel cusp is a prefabricated device made of austenitic alloys or alloys...

21 CFR 872.3350 - Gold or stainless steel cusp.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gold or stainless steel cusp. 872.3350 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3350 Gold or stainless steel cusp. (a) Identification. A gold or stainless steel cusp is a prefabricated device made of austenitic alloys or alloys...

21 CFR 872.3350 - Gold or stainless steel cusp.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gold or stainless steel cusp. 872.3350 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3350 Gold or stainless steel cusp. (a) Identification. A gold or stainless steel cusp is a prefabricated device made of austenitic alloys or alloys...

Cusp observation at Saturn's high-latitude magnetosphere by the Cassini spacecraft.

PubMed

Jasinski, J M; Arridge, C S; Lamy, L; Leisner, J S; Thomsen, M F; Mitchell, D G; Coates, A J; Radioti, A; Jones, G H; Roussos, E; Krupp, N; Grodent, D; Dougherty, M K; Waite, J H

2014-03-16

We report on the first analysis of magnetospheric cusp observations at Saturn by multiple in situ instruments onboard the Cassini spacecraft. Using this we infer the process of reconnection was occurring at Saturn's magnetopause. This agrees with remote observations that showed the associated auroral signatures of reconnection. Cassini crossed the northern cusp around noon local time along a poleward trajectory. The spacecraft observed ion energy-latitude dispersions-a characteristic signature of the terrestrial cusp. This ion dispersion is "stepped," which shows that the reconnection is pulsed. The ion energy-pitch angle dispersions suggest that the field-aligned distance from the cusp to the reconnection site varies between ∼27 and 51 R S . An intensification of lower frequencies of the Saturn kilometric radiation emissions suggests the prior arrival of a solar wind shock front, compressing the magnetosphere and providing more favorable conditions for magnetopause reconnection. We observe evidence for reconnection in the cusp plasma at SaturnWe present evidence that the reconnection process can be pulsed at SaturnSaturn's cusp shows similar characteristics to the terrestrial cusp.

Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field

NASA Astrophysics Data System (ADS)

Arthur, N. A.; Foster, J. E.; Barnat, E. V.

2018-05-01

Two-dimensional electron density measurements are made in a magnetic ring cusp discharge using laser collisional induced fluorescence. The magnet rings are isolated from the anode structure such that they can be biased independently in order to modulate electron flows through the magnetic cusps. Electron density images are captured as a function of bias voltage in order to assess the effects of current flow through the cusp on the spatial extent of the cusp. We anticipated that for a fixed current density being funneled through the magnetic cusp, the leak width would necessarily increase. Unexpectedly, the leak width, as measured by LCIF images, does not increase. This suggests that the current density is not constant, and that possibly either electrons are being heated or additional ionization events are occurring within the cusp. Spatially resolving electron temperature would be needed to determine if electrons are being heated within the cusp. We also observe breakdown of the anode magnetosheath and formation of anode spots at high bias voltage.

On the evolutionary advantage of multi-cusped teeth

PubMed Central

Bush, Mark B.; Barani, Amir; Lawn, Brian R.

2016-01-01

A hallmark of mammalian evolution is a progressive complexity in postcanine tooth morphology. However, the driving force for this complexity remains unclear: whether to expand the versatility in diet source, or to bolster tooth structural integrity. In this study, we take a quantitative approach to this question by examining the roles of number, position and height of multiple cusps in determining sustainable bite forces. Our approach is to use an extended finite-element methodology with due provision for step-by-step growth of an embedded crack to determine how fracture progresses with increasing occlusal load. We argue that multi-cusp postcanine teeth are well configured to withstand high bite forces provided that multiple cusps are contacted simultaneously to share the load. However, contact on a single near-wall cusp diminishes the strength. Location of the load points and cusp height, rather than cusp number or radius, are principal governing factors. Given these findings, we conclude that while complex tooth structures can enhance durability, increases in cusp number are more likely to be driven by the demands of food manipulation. Structural integrity of complex teeth is maintained when individual cusps remain sufficiently distant from the side walls and do not become excessively tall relative to tooth width. PMID:27558851

Parallel computation of fluid-structural interactions using high resolution upwind schemes

NASA Astrophysics Data System (ADS)

Hu, Zongjun

An efficient and accurate solver is developed to simulate the non-linear fluid-structural interactions in turbomachinery flutter flows. A new low diffusion E-CUSP scheme, Zha CUSP scheme, is developed to improve the efficiency and accuracy of the inviscid flux computation. The 3D unsteady Navier-Stokes equations with the Baldwin-Lomax turbulence model are solved using the finite volume method with the dual-time stepping scheme. The linearized equations are solved with Gauss-Seidel line iterations. The parallel computation is implemented using MPI protocol. The solver is validated with 2D cases for its turbulence modeling, parallel computation and unsteady calculation. The Zha CUSP scheme is validated with 2D cases, including a supersonic flat plate boundary layer, a transonic converging-diverging nozzle and a transonic inlet diffuser. The Zha CUSP2 scheme is tested with 3D cases, including a circular-to-rectangular nozzle, a subsonic compressor cascade and a transonic channel. The Zha CUSP schemes are proved to be accurate, robust and efficient in these tests. The steady and unsteady separation flows in a 3D stationary cascade under high incidence and three inlet Mach numbers are calculated to study the steady state separation flow patterns and their unsteady oscillation characteristics. The leading edge vortex shedding is the mechanism behind the unsteady characteristics of the high incidence separated flows. The separation flow characteristics is affected by the inlet Mach number. The blade aeroelasticity of a linear cascade with forced oscillating blades is studied using parallel computation. A simplified two-passage cascade with periodic boundary condition is first calculated under a medium frequency and a low incidence. The full scale cascade with 9 blades and two end walls is then studied more extensively under three oscillation frequencies and two incidence angles. The end wall influence and the blade stability are studied and compared under different frequencies and incidence angles. The Zha CUSP schemes are the first time to be applied in moving grid systems and 2D and 3D calculations. The implicit Gauss-Seidel iteration with dual time stepping is the first time to be used for moving grid systems. The NASA flutter cascade is the first time to be calculated in full scale.

Feedbacks of Composition and Neutral Density Changes on the Structure of the Cusp Density Anomaly

NASA Astrophysics Data System (ADS)

Brinkman, D. G.; Walterscheid, R. L.; Clemmons, J. H.

2015-12-01

The Earth's magnetospheric cusp provides direct access of energetic particles to the thermosphere. These particles produce ionization and kinetic (particle) heating of the atmosphere. The increased ionization coupled with enhanced electric fields in the cusp produces increased Joule heating and ion drag forcing. These energy inputs cause large wind and temperature changes in the cusp region. Measurements by the CHAMP satellite (460-390- km altitude) have shown strongly enhanced density in the cusp region. The Streak mission (325-123 km), on the other hand, showed a relative depletion. The atmospheric response in the cusp can be sensitive to composition and neutral density changes. In response to heating in the cusp, air of heavier mean molecular weight is brought up from lower altitudes significantly affecting pressure gradients. This opposes the effects of temperature change due to heating and in-turn affects the density and winds produced in the cusp. Also changes in neutral density change the interaction between precipitating particles and the atmosphere and thus change heating rates and ionization in the region affected by cusp precipitation. In this study we assess the sensitivity of the wind and neutral density structure in the cusp region to changes in the mean molecular weight induced by neutral dynamics, and the changes in particle heating rates and ionization which result from changes in neutral density. We use a high resolution two-dimensional time-dependent nonhydrostatic nonlinear dynamical model where inputs can be systematically altered. The resolution of the model allows us to examine the complete range of cusp widths. We compare the current simulations to observations by CHAMP and Streak. Acknowledgements: This research was supported by The Aerospace Corporation's Technical Investment program

Valve-sparing reimplantation for neoaortic root dilatation and regurgitation with an unbalanced cusp after the arterial switch operation.

PubMed

Yoneyama, Fumiya; Okamura, Toru; Harada, Yorikazu; Okita, Yutaka

2018-02-01

A 13-year-old male presented with neoaortic root dilatation and severe aortic valve regurgitation 13 years following an arterial switch operation. The valve cusps were unbalanced due to an enlarged non-coronary cusp. A valve-sparing reimplantation with a cusp plication was performed which resulted in a competent valve with trivial regurgitation. Thus, even in an unbalanced cusp, valve-sparing reimplantation can be used for neoaortic root dilatation and valve regurgitation after an arterial switch operation. © 2018 Wiley Periodicals, Inc.

Genetic integration of molar cusp size variation in baboons

PubMed Central

Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T.; Fletcher, Zachary; Mahaney, Michael C.; Hlusko, Leslea J.

2010-01-01

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the non-occluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. PMID:20034010

Genetic integration of molar cusp size variation in baboons.

PubMed

Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T; Fletcher, Zachary; Mahaney, Michael C; Hlusko, Leslea J

2010-06-01

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the nonoccluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. Copyright 2009 Wiley-Liss, Inc.

First records of talon cusps on baboon maxillary incisors argue for standardizing terminology and prompt a hypothesis of their formation.

PubMed

Heaton, Jason L; Pickering, Travis Rayne

2013-12-01

Dental characters can provide vital clues for understanding intra- and intertaxonomic morphological variation and its underlying genetic and environmental components. However, the unambiguous identification of particular traits and their comparative study is often confounded by lack of consistent terminology in the relevant literature. This difficulty is exacerbated when the etiologies are not completely understood, as is the case with talon cusps. To date, research on talon cusps has focused on modern humans. In many instances, descriptions of talon cusps appear in clinical case studies focusing on their treatment and removal. What is lacking in those discussions, though, is a comparative framework, in which the occurrence of talon cusps in nonhuman primates, and possibly other mammals, is established and understood. Here, we report on a taloned upper central incisor of a wild baboon (Papio hamadryas ursinus) from South Africa. The anomalous incisor of this individual includes an exaggerated accessory cusp diagnosed as a Type II talon. Microcomputed tomographic and radiographic analyses show that the taloned cusp possesses enamel, dentin, and pulp. In addition, we identified an unclassifiable talon cusp on a central maxillary incisor of a baboon skull housed in the Smithsonian Institution's Natural History Museum collection. Our observations of talon cusps on baboon incisors demonstrate that, with regard to this phenomenon, systematic study of nonhuman primates is much needed, along with a consistent use of terminology in the anatomical and anthropological literature. Finally, we present a hypothesis of the formation of talon cusps on mammalian incisors. Copyright © 2013 Wiley Periodicals, Inc.

Statistical Study in the mid-altitude cusp region: wave and particle data comparison using a normalized cusp crossing duration

NASA Astrophysics Data System (ADS)

Grison, B.; Escoubet, C. P.; Pitout, F.; Cornilleau-Wehrlin, N.; Dandouras, I.; Lucek, E.

2009-04-01

In the mid altitude cusp region the DC magnetic field presents a diamagnetic cavity due to intense ion earthward flux coming from the magnetosheath. A strong ultra low frequency (ULF) magnetic activity is also commonly observed in this region. Most of the mid altitude cusp statistical studies have focused on the location of the cusp and its dependence and response to solar wind, interplanetary magnetic field, dipole tilt angle parameters. In our study we use the database build by Pitout et al. (2006) in order to study the link of wave power in the ULF range (0.35-10Hz) measured by STAFF SC instrument with the ion plasma properties as measured by CIS (and CODIF) instrument as well as the diamagnetic cavity in the mid-altitude cusp region with FGM data. To compare the different crossings we don`t use the cusp position and dynamics but we use a normalized cusp crossing duration that permits to easily average the properties over a large number of crossings. As usual in the cusp, it is particularly relevant to sort the crossings by the corresponding interplanetary magnetic field (IMF) orientation in order to analyse the results. In particular we try to find out what is the most relevant parameter to link the strong wave activity with. The global statistic confirms previous single case observations that have noticed a simultaneity between ion injections and wave activity enhancements. We will also present results concerning other ion parameters and the diamagnetic cavity observed in the mid altitude cusp region.

Beach cusp destruction, formation, and evolution during and subsequent to an extratropical storm, Duck, North Carolina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, J.R.; Miller, S.M.O.; Torzynski, C.A.

Many studies have debated whether beach cusps are erosional or depositional features. The April 12-14, 1988, extratropical storm provided an opportunity to view the direct effects of one of the largest storms of the past decade upon beach sedimentology and morphology on barrier islands near Duck, North Carolina. Prior to the storm, the beach at Duck was characterized by a well-defined pattern of beach cusps with horn-to-horn spacings averaging 35 m. Storm-induced alterations were dominated by an initial period of beach erosion that remobilized the upper 30 to 50 cm of beach sediment, followed by aggradation. Net aggradation was mostmore » prominent along the middle beachface and within the pre-storm cusp bays. These morphologic adjustments resulted in the destruction of cusps, which were replaced with a post-storm planar beachface composed of horizontally bedded fine- to coarse-grained sediments. Within 24 hrs of storm subsidence, new beach cusps formed sequentially along the coast in the direction of longshore transport. Initial cusp formation resulted from beach erosion and the creation of bays in the planar storm-beach surface at positions of preferential post-storm runup. The initial cusp horns were composed of truncated horizontal beds of the planar beach accreted during the storm. After their formation, the cusps sequentially migrated downdrift. Migrating horns were composed of a coarse-grained sediment wedge that thickened toward horn crests, suggesting formation by deposition. It is concluded from these observations that beach cusps are both erosional and depositional in nature.« less

Features of polar cusp electron precipitation associated with a large magnetic storm

NASA Technical Reports Server (NTRS)

Berko, F. W.

1974-01-01

Measurements of precipitating electrons made by the OGO-4 satellite reveal several interesting phenomena in the polar cusp. Extremely high fluxes of 0.7 keV electrons were observed in the polar cusp ninety minutes following the sudden commencement of a very large magnetic storm. Structured, fairly high fluxes of 7.3 keV electrons were also observed in the cusp region, accompanied by very strong search coil magnetometer fluctuations, indicative of strong field-aligned currents. The observations confirm previously reported latitudinal shifts in the location of the polar cusp in response to southward interplanetary magnetic fields.

Particle Detectors and Data Analysis for Cusp Transient Features Campaign

NASA Technical Reports Server (NTRS)

Sharber, J. R.

1998-01-01

Grant NAG5-5084 was awarded to support the participation of South West Research Institute (SwRI) in building the energy per unit charge particle detectors for the Cusp Transient Features Campaign and analysis of flight data from these instruments. The detectors are part of an instrumented payload (Rocket 36.152, Dr. R. Pfaff, P.I.) launched from Svalbard on December 3, 1997, into the dark cusp. The particle instruments, a Cusp Electron Detector (CED) and a Cusp Ion Detector (CID), built on this project, provided differential energy and angular measurements along the rocket trajectory throughout the flight.

Feedbacks of Composition and Neutral Density Changes on the Structure of the Cusp Density Anomaly

NASA Astrophysics Data System (ADS)

Brinkman, D. G.; Walterscheid, R. L.; Clemmons, J. H.

2016-12-01

The Earth's magnetospheric cusp provides direct access of energetic particles to the thermosphere. These particles produce ionization and kinetic (particle) heating of the atmosphere. The increased ionization coupled with enhanced electric fields in the cusp produces increased Joule heating and ion drag forcing. These energy inputs cause large wind and temperature changes in the cusp region. Measurements by the CHAMP satellite (460-390- km altitude) have shown strongly enhanced density in the cusp region. The Streak mission (325-123 km), on the other hand, showed a relative depletion. The atmospheric response in the cusp can be sensitive to composition and neutral density changes. In response to heating in the cusp, air of heavier mean molecular weight is brought up from lower altitudes significantly affecting pressure gradients. This opposes the effects of temperature change due to heating and in-turn affects the density and winds produced in the cusp. Also changes in neutral density change the interaction between precipitating particles and the atmosphere and thus change heating rates and ionization in the region affected by cusp precipitation. In this study we assess the sensitivity of the wind and neutral density structure in the cusp region to changes in the mean molecular weight induced by neutral dynamics via advection, and the changes in particle heating rates and ionization which result from changes in neutral density. We use a high resolution two-dimensional time-dependent nonhydrostatic nonlinear dynamical model where inputs can be systematically altered. The resolution of the model allows us to examine the complete range of cusp widths. We compare the current simulations to observations by CHAMP and Streak. Acknowledgements: This material is based upon work supported by the National Aeronautics and Space Administration under Grant: NNX16AH46G issues through the Heliophysics Supporting Research Program. This research was also supported by The Aerospace Corporation's Technical Investment program

High-Energy Electron Confinement in a Magnetic Cusp Configuration

NASA Astrophysics Data System (ADS)

Park, Jaeyoung; Krall, Nicholas A.; Sieck, Paul E.; Offermann, Dustin T.; Skillicorn, Michael; Sanchez, Andrew; Davis, Kevin; Alderson, Eric; Lapenta, Giovanni

2015-04-01

We report experimental results validating the concept that plasma confinement is enhanced in a magnetic cusp configuration when β (plasma pressure/magnetic field pressure) is of order unity. This enhancement is required for a fusion power reactor based on cusp confinement to be feasible. The magnetic cusp configuration possesses a critical advantage: the plasma is stable to large scale perturbations. However, early work indicated that plasma loss rates in a reactor based on a cusp configuration were too large for net power production. Grad and others theorized that at high β a sharp boundary would form between the plasma and the magnetic field, leading to substantially smaller loss rates. While not able to confirm the details of Grad's work, the current experiment does validate, for the first time, the conjecture that confinement is substantially improved at high β . This represents critical progress toward an understanding of the plasma dynamics in a high-β cusp system. We hope that these results will stimulate a renewed interest in the cusp configuration as a fusion confinement candidate. In addition, the enhanced high-energy electron confinement resolves a key impediment to progress of the Polywell fusion concept, which combines a high-β cusp configuration with electrostatic fusion for a compact, power-producing nuclear fusion reactor.

Plasma rotation in the Peking University Plasma Test device.

PubMed

Xiao, Chijie; Chen, Yihang; Yang, Xiaoyi; Xu, Tianchao; Wang, Long; Xu, Min; Guo, Dong; Yu, Yi; Lin, Chen

2016-11-01

Some preliminary results of plasma rotations in a linear plasma experiment device, Peking University Plasma Test (PPT) device, are reported in this paper. PPT has a cylindrical vacuum chamber with 500 mm diameter and 1000 mm length, and a pair of Helmholtz coils which can generate cylindrical or cusp magnetic geometry with magnitude from 0 to 2000 G. Plasma was generated by a helicon source and the typical density is about 10 13 cm -3 for the argon plasma. Some Langmuir probes, magnetic probes, and one high-speed camera are set up to diagnose the rotational plasmas. The preliminary results show that magnetic fluctuations exist during some plasma rotation processes with both cylindrical and cusp magnetic geometries, which might be related to some electromagnetic processes and need further studies.

Aortic regurgitation due to fibrous strand rupture in the fenestrated left coronary cusp of the tricuspid aortic valve.

PubMed

Irisawa, Yusuke; Itatani, Keiichi; Kitamura, Tadashi; Hanayama, Naoji; Oka, Norihiko; Tomoyasu, Takahiro; Inoue, Nobuyuki; Hayashi, Hidenori; Inoue, Takamichi; Miyaji, Kagami

2014-01-01

Fenestration-related massive aortic regurgitation is rare. The underlying mechanism is reported to be rupture of the fenestrated fibrous strand, and most ruptured cords have been reported in the bicuspid valve or in the right coronary cusp of the tricuspid aortic valve. We encountered a rare case of acute aortic regurgitation due to fibrous strand rupture in the fenestrated left coronary cusp. Preoperative echocardiography detected left coronary cusp prolapse, and operative findings revealed rupture of a fibrous strand in the left coronary cusp. For cases such as this, preoperative echocardiography would be useful for appropriate diagnosis.

Density Variations in the Earth's Magnetospheric Cusps

NASA Technical Reports Server (NTRS)

Walsh, B. M.; Niehof, J.; Collier, M. R.; Welling, D. T.; Sibeck, D. G.; Mozer, F. S.; Fritz, T. A.; Kuntz, K. D.

2016-01-01

Seven years of measurements from the Polar spacecraft are surveyed to monitor the variations of plasma density within the magnetospheric cusps. The spacecraft's orbital precession from 1998 through 2005 allows for coverage of both the northern and southern cusps from low altitude out to the magnetopause. In the mid- and high- altitude cusps, plasma density scales well with the solar wind density (n(sub cusp)/n(sub sw) approximately 0.8). This trend is fairly steady for radial distances greater then 4 R(sub E). At low altitudes (r less than 4R(sub E)) the density increases with decreasing altitude and even exceeds the solar wind density due to contributions from the ionosphere. The density of high charge state oxygen (O(greater +2) also displays a positive trend with solar wind density within the cusp. A multifluid simulation with the Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme MHD model was run to monitor the relative contributions of the ionosphere and solar wind plasma within the cusp. The simulation provides similar results to the statistical measurements from Polar and confirms the presence of ionospheric plasma at low altitudes.

TIDAL STIRRING OF SATELLITES WITH SHALLOW DENSITY PROFILES PREVENTS THEM FROM BEING TOO BIG TO FAIL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomozeiu, Mihai; Mayer, Lucio; Quinn, Thomas, E-mail: mihai@physik.uzh.ch

The “too big to fail” problem is revisited by studying the tidal evolution of populations of dwarf satellites with different density profiles. The high-resolution cosmological ΛCDM “ErisMod” set of simulations is used. These simulations can model both the stellar and dark matter components of the satellites, and their evolution under the action of the tides of a Milky Way (MW)-sized host halo at a force resolution better than 10 pc. The stronger tidal mass loss and re-shaping of the mass distribution induced in satellites with γ = 0.6 dark matter density distributions, as those resulting from the effect of feedbackmore » in hydrodynamical simulations of dwarf galaxy formation, are sufficient to bring the circular velocity profiles in agreement with the kinematics of MW’s dSphs. In contrast, in simulations in which the satellites retain cusps at z = 0 there are several “massive failures” with circular velocities in excess of the observational constraints. Various sources of deviations in the conventionally adopted relation between the circular velocity at the half-light radius and the one-dimensional line of sight velocity dispersions are found. Such deviations are caused by the response of circular velocity profiles to tidal effects, which also varies depending on the initially assumed inner density profile and by the complexity of the stellar kinematics, which include residual rotation and anisotropy. In addition, tidal effects naturally induce large deviations in the stellar mass–halo mass relation for halo masses below 10{sup 9} M {sub ⊙}, preventing any reliable application of the abundance matching technique to dwarf galaxy satellites.« less

SIDM on FIRE: hydrodynamical self-interacting dark matter simulations of low-mass dwarf galaxies

NASA Astrophysics Data System (ADS)

Robles, Victor H.; Bullock, James S.; Elbert, Oliver D.; Fitts, Alex; González-Samaniego, Alejandro; Boylan-Kolchin, Michael; Hopkins, Philip F.; Faucher-Giguère, Claude-André; Kereš, Dušan; Hayward, Christopher C.

2017-12-01

We compare a suite of four simulated dwarf galaxies formed in 1010 M⊙ haloes of collisionless cold dark matter (CDM) with galaxies simulated in the same haloes with an identical galaxy formation model but a non-zero cross-section for DM self-interactions. These cosmological zoom-in simulations are part of the Feedback In Realistic Environments (FIRE) project and utilize the FIRE-2 model for hydrodynamics and galaxy formation physics. We find the stellar masses of the galaxies formed in self-interacting dark matter (SIDM) with σ/m = 1 cm2 g-1 are very similar to those in CDM (spanning M⋆ ≈ 105.7-7.0M⊙) and all runs lie on a similar stellar mass-size relation. The logarithmic DM density slope (α = d log ρ/d log r) in the central 250-500 pc remains steeper than α = -0.8 for the CDM-Hydro simulations with stellar mass M⋆ ∼ 106.6 M⊙ and core-like in the most massive galaxy. In contrast, every SIDM hydrodynamic simulation yields a flatter profile, with α > -0.4. Moreover, the central density profiles predicted in SIDM runs without baryons are similar to the SIDM runs that include FIRE-2 baryonic physics. Thus, SIDM appears to be much more robust to the inclusion of (potentially uncertain) baryonic physics than CDM on this mass scale, suggesting that SIDM will be easier to falsify than CDM using low-mass galaxies. Our FIRE simulations predict that galaxies less massive than M⋆ ≲ 3 × 106 M⊙ provide potentially ideal targets for discriminating models, with SIDM producing substantial cores in such tiny galaxies and CDM producing cusps.

A field data assessment of contemporary models of beach cusp formation

USGS Publications Warehouse

Allen, J.R.; Psuty, N.P.; Bauer, B.O.; Carter, R.W.G.

1996-01-01

Cusp formation was observed during an instrumented, daily profiled, time series of a reflective beach in Canaveral National Seashore, Florida on January 5, 1988. The monitored cusp embayment formed by erosion of the foreshore and the cusp series had a mean spacing of approximately 28 m. During this time, inshore fluid flows were dominated by two standing edge waves at frequencies of 0.06 Hz (primary) and 0.035 Hz (secondary) whereas incident waves were broadbanded at 0.12-0.16 Hz. Directly measured flows (and indirectly estimated swash excursion) data support both the standing wave subharmonic model and the self-organization model of cusp formation in this study.

CEP populations observed by ISEE 1

NASA Astrophysics Data System (ADS)

Whitaker, Katherine E.; Chen, Jiasheng; Fritz, Theodore A.

2006-12-01

Observations on October 30, 1978 show the ISEE 1 spacecraft passing though the high-altitude dayside northern cusp region from roughly 16:00 to 18:30 UT, during a slow solar wind period (~380 km/s). More than two orders of magnitude enhancements of the cusp energetic particle (CEP) fluxes are observed along with a depressed and turbulent local magnetic field and both ionospheric and solar wind plasma. The clock angle of the local magnetic field is different from that of the IMF, implying that the spacecraft was indeed inside the magnetosphere. The observed variations of the pitch angle distributions provide a unique opportunity to determine the structure of the cusp. The CEP fluxes were measured at about 8.5 hours MLT when the IMF had both an 8-10 nT duskward and southward component. The dawnside location of the cusp under these IMF conditions is unexpected by the existing models. No obvious time-energy dispersion is measured for the CEP fluxes. The time evolution of the phase space density as the spacecraft crossed the cusp boundary layer exhibits a positive gradient pointed to the high-altitude cusp, indicating a probable cusp source of the energetic particles. Through a careful analysis of the data available, we report the first detailed study of the equatorial orbiting ISEE 1 spacecraft passing through the high altitude cusp region.

Interobserver error involved in independent attempts to measure cusp base areas of Pan M1s

PubMed Central

Bailey, Shara E; Pilbrow, Varsha C; Wood, Bernard A

2004-01-01

Cusp base areas measured from digitized images increase the amount of detailed quantitative information one can collect from post-canine crown morphology. Although this method is gaining wide usage for taxonomic analyses of extant and extinct hominoids, the techniques for digitizing images and taking measurements differ between researchers. The aim of this study was to investigate interobserver error in order to help assess the reliability of cusp base area measurement within extant and extinct hominoid taxa. Two of the authors measured individual cusp base areas and total cusp base area of 23 maxillary first molars (M1) of Pan. From these, relative cusp base areas were calculated. No statistically significant interobserver differences were found for either absolute or relative cusp base areas. On average the hypocone and paracone showed the least interobserver error (< 1%) whereas the protocone and metacone showed the most (2.6–4.5%). We suggest that the larger measurement error in the metacone/protocone is due primarily to either weakly defined fissure patterns and/or the presence of accessory occlusal features. Overall, levels of interobserver error are similar to those found for intraobserver error. The results of our study suggest that if certain prescribed standards are employed then cusp and crown base areas measured by different individuals can be pooled into a single database. PMID:15447691

Colliding holes in Riemann surfaces and quantum cluster algebras

NASA Astrophysics Data System (ADS)

Chekhov, Leonid; Mazzocco, Marta

2018-01-01

In this paper, we describe a new type of surgery for non-compact Riemann surfaces that naturally appears when colliding two holes or two sides of the same hole in an orientable Riemann surface with boundary (and possibly orbifold points). As a result of this surgery, bordered cusps appear on the boundary components of the Riemann surface. In Poincaré uniformization, these bordered cusps correspond to ideal triangles in the fundamental domain. We introduce the notion of bordered cusped Teichmüller space and endow it with a Poisson structure, quantization of which is achieved with a canonical quantum ordering. We give a complete combinatorial description of the bordered cusped Teichmüller space by introducing the notion of maximal cusped lamination, a lamination consisting of geodesic arcs between bordered cusps and closed geodesics homotopic to the boundaries such that it triangulates the Riemann surface. We show that each bordered cusp carries a natural decoration, i.e. a choice of a horocycle, so that the lengths of the arcs in the maximal cusped lamination are defined as λ-lengths in Thurston-Penner terminology. We compute the Goldman bracket explicitly in terms of these λ-lengths and show that the groupoid of flip morphisms acts as a generalized cluster algebra mutation. From the physical point of view, our construction provides an explicit coordinatization of moduli spaces of open/closed string worldsheets and their quantization.

Effective Power-Law Dependence of Lyapunov Exponents on the Central Mass in Galaxies

NASA Technical Reports Server (NTRS)

Delis, N.; Efthymiopoulos, C.; Kalapotharakos, C.

2015-01-01

Using both numerical and analytical approaches, we demonstrate the existence of an effective power-law relation L alpha m(sup p) between themean Lyapunov exponent L of stellar orbits chaotically scattered by a supermassive black hole (BH) in the centre of a galaxy and the mass parameter m, i.e. ratio of the mass of the BH over the mass of the galaxy. The exponent p is found numerically to obtain values in the range p approximately equals 0.3-0.5. We propose a theoretical interpretation of these exponents, based on estimates of local 'stretching numbers', i.e. local Lyapunov exponents at successive transits of the orbits through the BH's sphere of influence. We thus predict p = 2/3 - q with q approximately equaling 0.1-0.2. Our basic model refers to elliptical galaxy models with a central core. However, we find numerically that an effective power-law scaling of L with m holds also in models with central cusp, beyond a mass scale up to which chaos is dominated by the influence of the cusp itself. We finally show numerically that an analogous law exists also in disc galaxies with rotating bars. In the latter case, chaotic scattering by the BH affects mainly populations of thick tube-like orbits surrounding some low-order branches of the x(sub 1) family of periodic orbits, as well as its bifurcations at low-order resonances, mainly the inner Lindblad resonance and the 4/1 resonance. Implications of the correlations between L and m to determining the rate of secular evolution of galaxies are discussed.

Cusp-related Pc3-5 Wave Activity

NASA Astrophysics Data System (ADS)

Pilipenko, V.; Engebretson, M. J.; Kozlovsky, A.; Belakhovsky, V.; Lessard, M.; Yeoman, T. K.

2009-12-01

Pc3-5 pulsations were found to be an ubiquitous element of dayside ULF wave activity at the cusp region. We examine observations of Pc3-5 wave activity by search coil and flux-gate magnetometers at three locations on Svalbard, covering geomagnetic latitudes 74o-76o. To identify the ionospheric projections of the cusp, we use the width of the return signal from the SuperDARN Finland radar covering the Svalbard archipelago. The ULF meridional spatial structure is examined using the amplitude-phase gradient technique. This analysis shows no specific mode conversion pattern near the cusp region. The amplitude gradient mainly has the same direction at all frequencies, and only during periods when the cusp is shifted to very high latitudes, the gradient may change sign. The phase delay is chaotic and does not show any consistent pattern. This behavior corresponds to the occurrence of a localized peak in the latitudinal distribution of Pc3-5 power, but not under the cusp proper as was previously thought, but about several degrees southward from the equatorward cusp boundary. We suppose that compressional Pc3 fluctuations leaking from the magnetosheath into the entry layer of the magnetosphere can modulate the precipitating electron fluxes, which produce the ground response.

Structure of the Outer Cusp and Sources of the Cusp Precipitation during Intervals of a Horizontal IMF

NASA Technical Reports Server (NTRS)

Berchem, Jean; Nemecek, Z.; Safrankova, J.; Prech, L.; Simunek, J.; Sauvaud, J.-A.; Fedorov, A.; Stenuit, H.; Fuselier, S. A.; Savin, S.;

High-Latitude Neutral Density Structures Investigated by Utilizing Multi-Instrument Satellite Data and NRLMSISE-00 Simulations

NASA Astrophysics Data System (ADS)

Horvath, Ildiko; Lovell, Brian C.

2018-02-01

This study investigates various types of neutral density features developed in the cusp region during magnetically active and quiet times. Multi-instrument Challenging Minisatellite Payload data provide neutral density, electron temperature, neutral wind speed, and small-scale field-aligned current (SS-FAC) values. Gravity Recovery and Climate Experiment neutral density data are also employed. During active times, cusp densities or density spikes appeared with their underlying flow channels (FCs) and enhanced SS-FACs implying upwelling, fueled by Joule heating, within/above FCs. Both the moderate nightside cusp enhancements under disturbed conditions and the minor dayside cusp enhancements under quiet conditions developed without any underlying FC and enhanced SS-FACs implying the role of particle precipitation in their development. Observations demonstrate the relations of FCs, density spikes, and upwelling-related divergent flows and their connections to the underlying (1) dayside magnetopause reconnection depositing magnetospheric energy into the high-latitude region and (2) Joule heating-driven disturbance dynamo effects. Results provide observational evidence that the moderate nightside cusp enhancements and the minor dayside cusp enhancements detected developed due to direct heating by weak particle precipitation. Chemical compositions related to the dayside density spike and low cusp densities are modeled by Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended 2000. Modeled composition outputs for the dayside density spike's plasma environment depict some characteristic upwelling signatures. Oppositely, in the case of low dayside cusp densities, composition outputs show opposite characteristics due to the absence of upwelling.

Estimation and Psychometric Analysis of Component Profile Scores via Multivariate Generalizability Theory

ERIC Educational Resources Information Center

Grochowalski, Joseph H.

2015-01-01

Component Universe Score Profile analysis (CUSP) is introduced in this paper as a psychometric alternative to multivariate profile analysis. The theoretical foundations of CUSP analysis are reviewed, which include multivariate generalizability theory and constrained principal components analysis. Because CUSP is a combination of generalizability…

Evidence of Multiple Reconnection Lines at the Magnetopause from Cusp Observations

NASA Technical Reports Server (NTRS)

Trattner, K. J.; Petrinec, S. M.; Fuselier, S. A.; Omidi, N.; Sibeck, David Gary

2012-01-01

Recent global hybrid simulations investigated the formation of flux transfer events (FTEs) and their convection and interaction with the cusp. Based on these simulations, we have analyzed several Polar cusp crossings in the Northern Hemisphere to search for the signature of such FTEs in the energy distribution of downward precipitating ions: precipitating ion beams at different energies parallel to the ambient magnetic field and overlapping in time. Overlapping ion distributions in the cusp are usually attributed to a combination of variable ion acceleration during the magnetopause crossing together with the time-of-flight effect from the entry point to the observing satellite. Most "step up" ion cusp structures (steps in the ion energy dispersions) only overlap for the populations with large pitch angles and not for the parallel streaming populations. Such cusp structures are the signatures predicted by the pulsed reconnection model, where the reconnection rate at the magnetopause decreased to zero, physically separating convecting flux tubes and their parallel streaming ions. However, several Polar cusp events discussed in this study also show an energy overlap for parallel-streaming precipitating ions. This condition might be caused by reopening an already reconnected field line, forming a magnetic island (flux rope) at the magnetopause similar to that reported in global MHD and Hybrid simulations

Electromagnetic Ion Cyclotron Waves in the High Altitude Cusp: Polar Observations

NASA Technical Reports Server (NTRS)

Le, Guan; Blanco-Cano, X.; Russell, C. T.; Zhou, X.-W.; Mozer, F.; Trattner, K. J.; Fuselier, S. A.; Anderson, B. J.; Vondrak, Richard R. (Technical Monitor)

2001-01-01

High-resolution magnetic field data from the Polar Magnetic Field Experiment (MFE) show that narrow band waves at frequencies approximately 0.2 to 3 Hz are a permanent feature in the vicinity of the polar cusp. The waves have been found in the magnetosphere adjacent to the cusp (both poleward and equatorward of the cusp) and in the cusp itself. The occurrence of waves is coincident with depression of magnetic field strength associated with enhanced plasma density, indicating the entry of magnetosheath plasma into the cusp region. The wave frequencies are generally scaled by the local proton cyclotron frequency, and vary between 0.2 and 1.7 times local proton cyclotron frequency. This suggests that the waves are generated in the cusp region by the precipitating magnetosheath plasma. The properties of the waves are highly variable. The waves exhibit both lefthanded and right-handed polarization in the spacecraft frame. The propagation angles vary from nearly parallel to nearly perpendicular to the magnetic field. We find no correlation among wave frequency, propagation angle and polarization. Combined magnetic field and electric field data for the waves indicate that the energy flux of the waves is guided by the background magnetic field and points downward toward the ionosphere.

Experimental and analytical investigation of a modified ring cusp NSTAR engine

NASA Technical Reports Server (NTRS)

Sengupta, Anita

2005-01-01

A series of experimental measurements on a modified laboratory NSTAR engine were used to validate a zero dimensional analytical discharge performance model of a ring cusp ion thruster. The model predicts the discharge performance of a ring cusp NSTAR thruster as a function the magnetic field configuration, thruster geometry, and throttle level. Analytical formalisms for electron and ion confinement are used to predict the ionization efficiency for a given thruster design. Explicit determination of discharge loss and volume averaged plasma parameters are also obtained. The model was used to predict the performance of the nominal and modified three and four ring cusp 30-cm ion thruster configurations operating at the full power (2.3 kW) NSTAR throttle level. Experimental measurements of the modified engine configuration discharge loss compare well with the predicted value for propellant utilizations from 80 to 95%. The theory, as validated by experiment, indicates that increasing the magnetic strength of the minimum closed reduces maxwellian electron diffusion and electrostatically confines the ion population and subsequent loss to the anode wall. The theory also indicates that increasing the cusp strength and minimizing the cusp area improves primary electron confinement increasing the probability of an ionization collision prior to loss at the cusp.

Miniature ion thruster ring-cusp discharge performance and behavior

NASA Astrophysics Data System (ADS)

Dankongkakul, Ben; Wirz, Richard E.

2017-12-01

Miniature ion thrusters are an attractive option for a wide range of space missions due to their low power levels and high specific impulse. Thrusters using ring-cusp plasma discharges promise the highest performance, but are still limited by the challenges of efficiently maintaining a plasma discharge at such small scales (typically 1-3 cm diameter). This effort significantly advances the understanding of miniature-scale plasma discharges by comparing the performance and xenon plasma confinement behavior for 3-ring, 4-ring, and 5-ring cusp by using the 3 cm Miniature Xenon Ion thruster as a modifiable platform. By measuring and comparing the plasma and electron energy distribution maps throughout the discharge, we find that miniature ring-cusp plasma behavior is dominated by the high magnetic fields from the cusps; this can lead to high loss rates of high-energy primary electrons to the anode walls. However, the primary electron confinement was shown to considerably improve by imposing an axial magnetic field or by using cathode terminating cusps, which led to increases in the discharge efficiency of up to 50%. Even though these design modifications still present some challenges, they show promise to bypassing what were previously seen as inherent limitations to ring-cusp discharge efficiency at miniature scales.

Electromagnetic Ion Cyclotron Waves in the High-Altitude Cusp: Polar Observations

NASA Technical Reports Server (NTRS)

Le, G.; Blanco-Cano, X.; Russell, C. T.; Zhou, X.-W.; Mozer, F.; Trattner, K. J.; Fuselier, S. A.; Anderson, B. J.

2005-01-01

High-resolution magnetic field data from the Polar Magnetic Field Experiment (MFE) show that narrow-band waves at frequencies approx. 0.2-3 Hz are a permanent feature in the vicinity of the polar cusp. The waves have been found in the magnetosphere adjacent to the cusp (both poleward and equatorward of the cusp) and in the cusp itself. The occurrence of waves is coincident with depression of magnetic field strength associated with enhanced plasma density, indicating the entry of magnetosheath plasma into the cusp region. The wave frequencies are generally scaled by the local proton cyclotron frequency and vary between 0.2 and 1.7 times local proton cyclotron frequency. This suggests that the waves are generated in the cusp region by the precipitating magnetosheath plasma. The properties of the waves are highly variable. The waves exhibit both left-handed and right-handed polarization in the spacecraft frame. The propagation angles vary from nearly parallel to nearly perpendicular to the magnetic field. We find no correlation among wave frequency, propagation angle, and polarization. Combined magnetic field and electric field data for the waves indicate that the energy flux of the waves is guided by the background magnetic field and points downward toward the ionosphere.

Solar wind controls on Mercury's magnetospheric cusp

NASA Astrophysics Data System (ADS)

He, Maosheng; Vogt, Joachim; Heyner, Daniel; Zhong, Jun

2017-06-01

This study assesses the response of the cusp to solar wind changes comprehensively, using 2848 orbits of MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) observation. The assessment entails four steps: (1) propose and validate an approach to estimate the solar wind magnetic field (interplanetary magnetic field (IMF)) for MESSENGER's cusp transit; (2) define an index σ measuring the intensity of the magnetic disturbance which significantly peaks within the cusp and serves as an indicator of the cusp activity level; (3) construct an empirical model of σ as a function of IMF and Mercury's heliocentric distance rsun, through linear regression; and (4) use the model to estimate and compare the polar distribution of the disturbance σ under different conditions for a systematic comparison. The comparison illustrates that the disturbance peak over the cusp is strongest and widest extending in local time for negative IMF Bx and negative IMF Bz, and when Mercury is around the perihelion. Azimuthal shifts are associated with both IMF By and rsun: the cusp moves toward dawn when IMF By or rsun decrease. These dependences are explained in terms of the IMF Bx-controlled dayside magnetospheric topology, the component reconnection model applied to IMF By and Bz, and the variability of solar wind ram pressure associated with heliocentric distance rsun. The applicability of the component reconnection model on IMF By indicates that at Mercury reconnection occurs at lower shear angles than at Earth.