WorldWideScience

Sample records for single pulsating load

  1. Damage Accumulation in Vertical Breakwaters due to Combined Impact Loading and Pulsating Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Nielsen, Søren R. K.

    1999-01-01

    Vertical wall breakwaters used to protect for example an harbour from large waves usually consist of large concrete caissons placed on the seabed. The wave loads can be divided in two types, pulsating and impact loads. For some types of breakwaters especially the impact wave loads can be very large...

  2. Effect of counter-pulsation control of a pulsatile left ventricular assist device on working load variations of the native heart.

    Science.gov (United States)

    Choi, Seong Wook; Nam, Kyoung Won; Lim, Ki Moo; Shim, Eun Bo; Won, Yong Soon; Woo, Heung Myong; Kwak, Ho Hyun; Noh, Mi Ryoung; Kim, In Young; Park, Sung Min

    2014-04-03

    When using a pulsatile left ventricular assist device (LVAD), it is important to reduce the cardiac load variations of the native heart because severe cardiac load variations can induce ventricular arrhythmia. In this study, we investigated the effect of counter-pulsation control of the LVAD on the reduction of cardiac load variation. A ventricular electrocardiogram-based counter-pulsation control algorithm for a LVAD was implemented, and the effects of counter-pulsation control of the LVAD on the reduction of the working load variations of the left ventricle were determined in three animal experiments. Deviations of the working load of the left ventricle were reduced by 51.3%, 67.9%, and 71.5% in each case, and the beat-to-beat variation rates in the working load were reduced by 84.8%, 82.7%, and 88.2% in each ease after counter-pulsation control. There were 3 to 12 premature ventricle contractions (PVCs) before counter-pulsation control, but no PVCs were observed during counter-pulsation control. Counter-pulsation control of the pulsatile LVAD can reduce severe cardiac load variations, but the average working load is not markedly affected by application of counter-pulsation control because it is also influenced by temporary cardiac outflow variations. We believe that counter-pulsation control of the LVAD can improve the long-term safety of heart failure patients equipped with LVADs.

  3. Pulsating variables

    International Nuclear Information System (INIS)

    1989-01-01

    The study of stellar pulsations is a major route to the understanding of stellar structure and evolution. At the South African Astronomical Observatory (SAAO) the following stellar pulsation studies were undertaken: rapidly oscillating Ap stars; solar-like oscillations in stars; 8-Scuti type variability in a classical Am star; Beta Cephei variables; a pulsating white dwarf and its companion; RR Lyrae variables and galactic Cepheids. 4 figs

  4. Pulsating stars

    CERN Document Server

    Catelan, M?rcio

    2014-01-01

    The most recent and comprehensive book on pulsating stars which ties the observations to our present understanding of stellar pulsation and evolution theory.  Written by experienced researchers and authors in the field, this book includes the latest observational results and is valuable reading for astronomers, graduate students, nuclear physicists and high energy physicists.

  5. Influence of Hydraulic Design on Stability and on Pressure Pulsations in Francis Turbines at Overload, Part Load and Deep Part Load based on Numerical Simulations and Experimental Model Test Results

    International Nuclear Information System (INIS)

    Magnoli, M V; Maiwald, M

    2014-01-01

    Francis turbines have been running more and more frequently in part load conditions, in order to satisfy the new market requirements for more dynamic and flexible energy generation, ancillary services and grid regulation. The turbines should be able to be operated for longer durations with flows below the optimum point, going from part load to deep part load and even speed-no-load. These operating conditions are characterised by important unsteady flow phenomena taking place at the draft tube cone and in the runner channels, in the respective cases of part load and deep part load. The current expectations are that new Francis turbines present appropriate hydraulic stability and moderate pressure pulsations at overload, part load, deep part load and speed-no-load with high efficiency levels at normal operating range. This study presents series of investigations performed by Voith Hydro with the objective to improve the hydraulic stability of Francis turbines at overload, part load and deep part load, reduce pressure pulsations and enlarge the know-how about the transient fluid flow through the turbine at these challenging conditions. Model test measurements showed that distinct runner designs were able to influence the pressure pulsation level in the machine. Extensive experimental investigations focused on the runner deflector geometry, on runner features and how they could reduce the pressure oscillation level. The impact of design variants and machine configurations on the vortex rope at the draft tube cone at overload and part load and on the runner channel vortex at deep part load were experimentally observed and evaluated based on the measured pressure pulsation amplitudes. Numerical investigations were employed for improving the understanding of such dynamic fluid flow effects. As example for the design and experimental investigations, model test observations and pressure pulsation curves for Francis machines in mid specific speed range, around n qopt = 50

  6. Introduction to Single Piles under Lateral Loading

    DEFF Research Database (Denmark)

    Augustesen, Anders; Ibsen, Lars Bo

    The purpose of this chapter is to give a short introduction to single piles subjected to lateral loading. First, the observed behaviour of laterally loaded piles is described, i.e. the effects of loading conditions, installation procedure, pile type etc. on pile behaviour are presented (section 1.......2). The description is based on results of laboratory tests, full-scale field tests as well as numerical investigations presented in literature. Second, general methods that attempt to model lateral pile response are discussed in section 1.4. Third, focus is paid to a widely used method for prediction of the response...... of a lateral loaded pile, namely the Winkler approach in which the pile is modelled as an elastic beam on an elastic foundation (section 1.5). The soil response and thereby the elastic foundation is represented by springs with nonlinear behaviour (p-y curves). In section 1.6 different types and formulations...

  7. The pulsating white dwarfs

    Science.gov (United States)

    Robinson, E. L.

    1980-01-01

    The characteristics of variable white dwarfs are presented through an examination of observational data. The variable white dwarfs are normal, single, DA white dwarfs. The variations are caused by pulsations, but the pulsations are nonradial rather than radial pulsations. The periods are all very long. Excluding harmonics and cross frequencies, the shortest period is 114 sec and the longest period is 1186 sec. Without exception every variable is multiperiodic. The stability of the periods varies from extremely high to very low; the low stability of many of the variables perhaps being due to incomplete data. Finally, there is a strong correlation between the amplitude of the variations and their remaining properties. The higher amplitude variables have more periods in their light curves and the periods are more unstable.

  8. Load compensation for single phase system using series active filter ...

    African Journals Online (AJOL)

    In this paper a new control strategy for series active filter has been proposed for improvement of power quality problems in single phase system. Since the non linear loads in the system comprises of both voltage source harmonic and current source harmonic loads and the dominancy of each type of load varies from time to ...

  9. Pulsating white dwarfs

    Science.gov (United States)

    Kepler, S. O.; Romero, Alejandra D.

    2017-09-01

    The Sloan Digital Sky Survey has allowed us to increase the number of known white dwarfs by a factor of five and consequently the number of known pulsating white dwarfs also by a factor of five. It has also led to the discovery of new types of variable white dwarfs, as the variable hot DQs, and the pulsating Extremely Low Mass white dwarfs. With the Kepler Mission, it has been possible to discover new phenomena, the outbursts present in a few pulsating white dwarfs.

  10. Short-term heat load forecasting for single family houses

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

    2013-01-01

    This paper presents a method for forecasting the load for space heating in a single-family house. The forecasting model is built using data from sixteen houses located in Sønderborg, Denmark, combined with local climate measurements and weather forecasts. Every hour the hourly heat load for each...... house the following two days is forecasted. The forecast models are adaptive linear time-series models and the climate inputs used are: ambient temperature, global radiation and wind speed. A computationally efficient recursive least squares scheme is used. The models are optimized to fit the individual...

  11. Pulsating red variables

    International Nuclear Information System (INIS)

    Whitelock, P.A.

    1990-01-01

    The observational characteristics of pulsating red variables are reviewed with particular emphasis on the Miras. These variables represent the last stage in the evolution of stars on the Asymptotic Giant Branch (AGB). A large fraction of the IRAS sources in the Bulge are Mira variables and a subset of these are also OH/IR sources. Their periods range up to 720 days, though most are between 360 and 560 days. At a given period those stars with the highest pulsation amplitudes have the highest mass-loss rates; this is interpreted as evidence for a causal connection between mass-loss and pulsation. It is suggested that once an AGB star has become a Mira it will evolve with increasing pulsation amplitude and mass-loss, but with very little change of luminosity or logarithmic period. 26 refs

  12. Classical pulsating variables

    International Nuclear Information System (INIS)

    Hacke, G.

    1987-01-01

    The nature of the three types of classical pulsating variables (δ-Cephei stars, W-Virginis stars and RR-Lyrae stars) is studied. Problems of the light-curve analysis such as (1) the frequency distribution of periods for the three types of classical pulsating variables, (2) spurions periods, (3) changes of periods and multiple periodicity as well as (4) the Blazhko-effect and other changes of the light-curve form are discussed

  13. Load Insensitive, Low Voltage Quadrature Oscillator Using Single Active Element

    Directory of Open Access Journals (Sweden)

    Jitendra Mohan

    2017-01-01

    Full Text Available In this paper, a load insensitive quadrature oscillator using single differential voltage dual-X second generation current conveyor operated at low voltage is proposed. The proposed circuit employs single active element, three grounded resistors and two grounded capacitors. The proposed oscillator offers two load insensitive quadrature current outputs and three quadrature voltage outputs simultaneously. Effects of non-idealities along with the effects of parasitic are further studied. The proposed circuit enjoys the feature of low active and passive sensitivities. Additionally, a resistorless realization of the proposed quadrature oscillator is also explored. Simulation results using PSPICE program on cadence tool using 90 nm Complementary Metal Oxide Semiconductor (CMOS process parameters confirm the validity and practical utility of the proposed circuit.

  14. Source of temperature and pressure pulsations during sessile droplet evaporation into multicomponent atmospheres.

    Science.gov (United States)

    Persad, Aaron H; Sefiane, Khellil; Ward, Charles A

    2013-10-29

    During sessile droplet evaporation, studies with IR thermography and shadowgraphs have indicated temperature pulsations. We confirm those observations with microthermocouples, but microthermocouples also indicate temperature pulsations in the atmosphere of the droplet. The pressure in this atmosphere pulsated as well and was correlated with the temperature pulsations in the droplet. Also, we find that if a droplet evaporates into its own vapor, there are no temperature or pressure pulsations. The pulsations occur only if the droplet evaporates into an atmosphere with a component having a heat of solution with the droplet when it adsorbs-absorbs. None of the currently proposed mechanisms for the temperature pulsations provide an explanation for the coupling between the temperature pulsations in the droplet and the vapor-phase pressure pulsations, and for the absence of the pulsations when the system is single-component. As a mechanism for the pulsations, we propose that when a droplet is exposed to an atmosphere containing a component that has a heat of solution with the droplet, energy will be released from adsorption-absorption. This energy will cause pulsations in the evaporation flux, and these pulsations could cause the observed temperature and pressure pulsations. We examine this mechanism by showing that, if the measured temperature pulsations in a water droplet exposed to a methanol atmosphere are used as the input to a theory of evaporation kinetics (statistical rate theory), the pressure pulsations of the water vapor in the methanol atmosphere are predicted and agree with those measured with a quadrupole mass analyzer. When the inputs and outputs are reversed in the theory, we find that the temperature pulsations in the droplet are correctly predicted from the measured water vapor pulsations in the atmosphere.

  15. Immediate loading with single-piece implant following extraction

    Directory of Open Access Journals (Sweden)

    Hemlata Dwivedi

    2017-01-01

    Full Text Available Although dental implantology had evolved over a number of years, many dental surgeons are unaware of the concept of immediate loading with the use of one-piece implant that began in the early 1960s. The goal of successful prosthodontics rehabilitation is to provide function, esthetics, and comfort to the patient. The aim of this literature is to provide an overview of one-piece implant, with its advantages and disadvantages over conventional two-piece implant. Immediate prosthetic of a one-piece system allows for a better tissue healing and better adhesion of gingival mucosa to form a collar which is healthy and adherent to the implant, avoiding a second surgical procedure, and also includes a very important aspect esthetics. This article describes a case report of immediate loading with single-piece implant following extraction.

  16. Estimating DPL photomask fabrication load compared with single exposure

    Science.gov (United States)

    Toyama, Nobuhito; Inazuki, Yuichi; Sutou, Takanori; Nagai, Takaharu; Morikawa, Yasutaka; Mohri, Hiroshi; Hayashi, Naoya; Huckabay, Judy A.; Abe, Yoshikuni

    2007-10-01

    DPL (Double Patterning Lithography) has been identified as one of major candidates for 45nm and 32nm HP since ITRS2006update and several reports of the performance or challenges of DPL have been published. DPL requires at least two photomasks with tighter specification of image placement and the difference of mean to target according to ITRS2006update. On the other hand, approximately half of whole features of single layer are written on each photomask and the densest features are split into other photomask in consequence of pitch relaxation for DPL. Then the photomask writing data of two sets for DPL and single data for single exposure are evaluated for photomask fabrication load. The design will be automatically decomposed with EDA tool and OPC will be tuned as DPL or single exposure. Not only number of fractured features but also feasibility study of automatic decomposition will be presented and discussed. The consequences of relaxed pitch on process, inspection, repair, yield, MEEF and cycle time will be discussed with results as available.

  17. Excitation of Stellar Pulsations

    DEFF Research Database (Denmark)

    Houdek, G.

    2012-01-01

    In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the δ Scuti stars, and stars supporting solar-like oscillations....

  18. Pulsation of black holes

    Science.gov (United States)

    Gao, Changjun; Lu, Youjun; Shen, You-Gen; Faraoni, Valerio

    2018-01-01

    The Hawking-Penrose singularity theorem states that a singularity forms inside a black hole in general relativity. To remove this singularity one must resort to a more fundamental theory. Using a corrected dynamical equation arising in loop quantum cosmology and braneworld models, we study the gravitational collapse of a perfect fluid sphere with a rather general equation of state. In the frame of an observer comoving with this fluid, the sphere pulsates between a maximum and a minimum size, avoiding the singularity. The exterior geometry is also constructed. There are usually an outer and an inner apparent horizon, resembling the Reissner-Nordström situation. For a distant observer the horizon crossing occurs in an infinite time and the pulsations of the black hole quantum "beating heart" are completely unobservable. However, it may be observable if the black hole is not spherical symmetric and radiates gravitational wave due to the quadrupole moment, if any.

  19. Slowly pulsating B stars

    Science.gov (United States)

    Waelkens, C.

    1991-06-01

    Photometric data obtained during several years of observations of seven B-type stars are analyzed, including HD 74195 (Omicron Velorum), HD 74560 (HD 3467), HD 123515 (HR 5296), HD 143309, HD 160124, HD 177863 (HR 7241), and HD 181558 (HR 7339). Results indicate that all seven stars are multiperiodic variables with periods of the order of days. Two periods were identified for HD 177863, three periods for HD 74560 and HD 181558, four periods for HD 123515, five periods for HD 74195, six periods for HD 143309, and eight periods for HD 160124. The multiperiodicity and the amplitude behavior of these stars point toward pulsation in high-radial-order g-modes in the stars. It is suggested that these stars form a distinct group of early-type variables, which are named here 'slowly pulsating B stars'.

  20. Immediate non-occlusal loading of single implants in the aesthetic zone : A randomized clinical trial

    NARCIS (Netherlands)

    den Hartog, Laurens; Raghoebar, Gerry M.; Stellingsma, Kees; Vissink, Arjan; Meijer, Henny J. A.

    P>Aim This study compared the outcome of immediate non-occlusal loading with conventional loading for single implants in the maxillary aesthetic zone. It was hypothesized that immediate non-occlusal loading is not inferior to conventional loading. Materials and Methods Sixty-two patients with a

  1. Radiation tests for a single-GEM-loaded gaseous detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyong Sei; Hong, Byung Sik; Park, Sung Keun [Korea University, Seoul (Korea, Republic of); Kim, Sang Yeol [NoticeKorea, Anyang (Korea, Republic of)

    2014-11-15

    We report on a systematic study of a single-gas-electron-multiplier (GEM)-loaded gaseous detector developed for precision measurements of high-energy particle beams and for dose verification in particle therapy. In the present study, a 256-channel prototype detector having an active area of 16 x 16 cm{sup 2} and operating using a continuous current-integration-mode signal-processing method was manufactured and tested with X-rays emitted from a 70-kV X-ray generator and 43-MeV protons provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science(KIRAMS). The amplified detector response was measured for X-rays with an intensity of about 5 x 10{sup 6} Hz cm{sup -2}. The linearity of the detector response to the particle flux was examined and validated by using 43-MeV proton beams. The non-uniform development of the amplification for the gas electrons in space was corrected by applying a proper calibration to the channel responses of the measured beam-profile data. We conclude from the radiation tests that the detector developed in the present study will allow us to perform quality measurements of various high-energy particle beams and to apply the technology to dose-verification measurements in particle therapy.

  2. Clinical and radiographic outcome following immediate loading and delayed loading of single-tooth implants: Randomized clinical trial.

    Science.gov (United States)

    Gjelvold, Björn; Kisch, Jenö; Chrcanovic, Bruno Ramos; Albrektsson, Tomas; Wennerberg, Ann

    2017-06-01

    Immediate loading of single implants is generally considered a reliable procedure. The objective of the present prospective randomized clinical study was to compare the overall treatment outcome following immediate loading (IL) and delayed loading (DL) of single implants after 1 year of follow-up. Patients with a missing maxillary tooth (15-25) were randomly assigned to IL or DL. The protocol included implant installation in healed sites, immediate loading, delayed loading, temporary screw-retained restoration, and replacement with a permanent single implant crown. Outcome measures were implant survival, marginal bone level, soft tissue changes, papillae index, pink, and white esthetic score (PES and WES), patient judged aesthetics, and oral health impact profile (OHiP-14). Implant survival rate was 100% and 96% for IL and DL, respectively. Implant success rate was 96% and 88% for IL and DL, respectively. Statistically significant lower papilla index scores were found in the IL group at temporary crown and definitive crown placement. An overall statistically significant improvement after 12 months for PES, WES and OHIP-14 was found. This prospective randomized study showed that single implants in the maxilla can present satisfactory results with respect to either immediate loading or delayed loading after 12 months. © 2017 Wiley Periodicals, Inc.

  3. Functional adaptation to loading of a single bone is neuronally regulated and involves multiple bones.

    Science.gov (United States)

    Sample, Susannah J; Behan, Mary; Smith, Lesley; Oldenhoff, William E; Markel, Mark D; Kalscheur, Vicki L; Hao, Zhengling; Miletic, Vjekoslav; Muir, Peter

    2008-09-01

    Regulation of load-induced bone formation is considered a local phenomenon controlled by osteocytes, although it has also been hypothesized that functional adaptation may be neuronally regulated. The aim of this study was to examine bone formation in multiple bones, in response to loading of a single bone, and to determine whether adaptation may be neuronally regulated. Load-induced responses in the left and right ulnas and humeri were determined after loading of the right ulna in male Sprague-Dawley rats (69 +/- 16 days of age). After a single period of loading at -760-, -2000-, or -3750-microepsilon initial peak strain, rats were given calcein to label new bone formation. Bone formation and bone neuropeptide concentrations were determined at 10 days. In one group, temporary neuronal blocking was achieved by perineural anesthesia of the brachial plexus with bupivicaine during loading. We found right ulna loading induces adaptive responses in other bones in both thoracic limbs compared with Sham controls and that neuronal blocking during loading abrogated bone formation in the loaded ulna and other thoracic limb bones. Skeletal adaptation was more evident in distal long bones compared with proximal long bones. We also found that the single period of loading modulated bone neuropeptide concentrations persistently for 10 days. We conclude that functional adaptation to loading of a single bone in young rapidly growing rats is neuronally regulated and involves multiple bones. Persistent changes in bone neuropeptide concentrations after a single loading period suggest that plasticity exists in the innervation of bone.

  4. Microscopic observations during longitudinal compression loading of single pulp fibers

    Science.gov (United States)

    Irving B. Sachs

    1986-01-01

    Paperboard components (linerboard adn corrugating medium) fail in edgewise compression because of failure of single fibers, as well as fiber-to-fiber bonds. While fiber-to-fiber-bond failure has been studied extensively, little is known about the longitudinal compression failure of a single fiber. In this study, surface alterations on single loblolly pine kraft pulp...

  5. Pulsation of Ap-Stars

    Science.gov (United States)

    Weiss, W. W.; Schneider, H.

    1983-09-01

    It has been known for many centuries that one can determine by simple means if a barrel of wine is full, half empty, or- horribile dictu - empty. One knocks against the wall and listens to the echo. Another example of the same technique, but less interesting for the connaisseur en vin is given by seismology. Seismographs distributed all over the globe register earthquakes and since they are differently located with respect to an earthquake centre the registrations look different. From a comparison of such registrations geologists have extracted most of our knowledge about the structure and composition of the terrestrial interior. Corresponding experiments were also planned and successfully executed on the Moon and on Mars. Stellar astronomers, however, are not in the lucky position of their colleagues who work in our solar system with the help of satellites. They are limited to stars which pulsate voluntarily. We will not discuss here the question why some groups of stars pulsate and others do not. We shall only mention that pulsating stars have at least one layer in their interior which does not absorb pulsational energy, as is the case for the rest of the star, but produces energy of variable amount and in phase with PUlsation. This mechanism keeps the star pulsating as long as this (these) layer(s) exists. Oue to stellar evolution, diffusion, magnetic fields, to name only some possible mechanisms, these layers can disappear or undergo substantial changes so that the energy losses due to pulsation cannot be compensated anymore. Oamping will result and finally the star will become stable against pulsation.

  6. Pulsation research during the IMS

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, W.J.

    1982-08-01

    Workers in the pulsation field entered the period of the International Magnetospheric Study (IMS) with a lot of theories that needed testing. Because of this and the wealth of new data available from the IMS observational campaigns, many new observational results have emerged from the IMS. The experience of the IMS shows us that the most fruitful method of working has been small-scale collaborations, between either a few individuals or a few groups with complementary data sets. The larger, more formally organized workshops do not seem to have been as successful in producing results, though they may have fostered useful contacts. In the years to come I hope and expect to see more of this sort of small-scale collaboration; especially as the initial results obtainable from a single data set are now published, experiments should turn to seeing how their data can be used in conjunction with other data sets. I also feel that the time is ripe for more theoretical work. The IMS has left us with a lot of new observations that need explanation.

  7. Reduced Phrenic Motoneuron Recruitment during Sustained Inspiratory Threshold Loading Compared to Single-Breath Loading: A Twitch Interpolation Study.

    Science.gov (United States)

    Raux, Mathieu; Demoule, Alexandre; Redolfi, Stefania; Morelot-Panzini, Capucine; Similowski, Thomas

    2016-01-01

    In humans, inspiratory constraints engage cortical networks involving the supplementary motor area. Functional magnetic resonance imaging (fMRI) shows that the spread and intensity of the corresponding respiratory-related cortical activation dramatically decrease when a discrete load becomes sustained. This has been interpreted as reflecting motor cortical reorganization and automatisation, but could proceed from sensory and/or affective habituation. To corroborate the existence of motor reorganization between single-breath and sustained inspiratory loading (namely changes in motor neurones recruitment), we conducted a diaphragm twitch interpolation study based on the hypothesis that motor reorganization should result in changes in the twitch interpolation slope. Fourteen healthy subjects (age: 21-40 years) were studied. Bilateral phrenic stimulation was delivered at rest, upon prepared and targeted voluntary inspiratory efforts ("vol"), upon unprepared inspiratory efforts against a single-breath inspiratory threshold load ("single-breath"), and upon sustained inspiratory efforts against the same type of load ("continuous"). The slope of the relationship between diaphragm twitch transdiaphragmatic pressure and the underlying transdiaphragmatic pressure was -1.1 ± 0.2 during "vol," -1.5 ± 0.7 during "single-breath," and -0.6 ± 0.4 during "continuous" (all slopes expressed in percent of baseline.percent of baseline -1 ) all comparisons significant at the 5% level. The contribution of the diaphragm to inspiration, as assessed by the gastric pressure to transdiaphragmatic pressure ratio, was 31 ± 17% during "vol," 22 ± 16% during "single-breath" ( p = 0.13), and 19 ± 9% during "continuous" ( p = 0.0015 vs. "vol"). This study shows that the relationship between the amplitude of the transdiaphragmatic pressure produced by a diaphragm twitch and its counterpart produced by the underlying diaphragm contraction is not unequivocal. If twitch interpolation is

  8. Reduced phrenic motoneuron recruitment during sustained inspiratory threshold loading compared to single-breath loading: a twitch interpolation study

    Directory of Open Access Journals (Sweden)

    Mathieu Raux

    2016-11-01

    Full Text Available In humans, inspiratory constraints engage cortical networks involving the supplementary motor area. Functional magnetic resonance imaging (fMRI shows that the spread and intensity of the corresponding respiratory-related cortical activation dramatically decrease when a discrete load becomes sustained. This has been interpreted as reflecting motor cortical reorganisation and automatisation, but could proceed from sensory and/or affective habituation. To corroborate the existence of motor reorganisation between single-breath and sustained inspiratory loading (namely changes in motor neurones recruitment, we conducted a diaphragm twitch interpolation study based on the hypothesis that motor reorganisation should result in changes in the twitch interpolation slope. Fourteen healthy subjects (age: 21 – 40 years were studied. Bilateral phrenic stimulation was delivered at rest, upon prepared and targeted voluntary inspiratory efforts (vol, upon unprepared inspiratory efforts against a single-breath inspiratory threshold load (single-breath, and upon sustained inspiratory efforts against the same type of load (continuous. The slope of the relationship between diaphragm twitch transdiaphragmatic pressure and the underlying transdiaphragmatic pressure was –1.1 ± 0.2 during vol, –1.5 ± 0.7 during single-breath, and -0.6 ± 0.4 during continuous (all slopes expressed in percent of baseline.percent of baseline-1 all comparisons significant at the 5% level. The contribution of the diaphragm to inspiration, as assessed by the gastric pressure to transdiaphragmatic pressure ratio, was 31 ± 17 % during vol, 22 ± 16 % during single-breath (p=0.13, and 19 ± 9 % during continuous (p = 0.0015 vs. vol. This study shows that the relationship between the amplitude of the transdiaphragmatic pressure produced by a diaphragm twitch and its counterpart produced by the underlying diaphragm contraction is not unequivocal. If twitch interpolation is interpreted as

  9. Effect of single physical load of different duration and intensity on cognitive function.

    Science.gov (United States)

    Sipavičienė, Saulė; Dumčienė, Audronė; Ramanauskienė, Irina; Skurvydas, Albertas

    2012-01-01

    The aim of this study was to determine the effect of a single physical load of different duration and intensity on cognitive function. The study population comprised 90 male soldiers. The subjects were randomly divided into two groups: experimental (n=60) and control group (n=30). The soldiers in the experimental group undertook 3 specific loads of different types, durations, and intensities. Attention concentration and tapping tests were carried out, and the reaction time was measured. After the physical load, the soldiers in the experimental group performed the attention concentration test faster, the number of committed mistakes decreased, and the rate of processing information increased as compared to the corresponding values before physical load (all Preaction time, in the experimental group were found to be worse than before physical loads (P<0.05). No significant changes were observed in the control group of soldiers. Despite fatigue, a single physical load of different duration and intensity improved the cognitive function.

  10. Pulsating Star Mystery Solved

    Science.gov (United States)

    2010-11-01

    By discovering the first double star where a pulsating Cepheid variable and another star pass in front of one another, an international team of astronomers has solved a decades-old mystery. The rare alignment of the orbits of the two stars in the double star system has allowed a measurement of the Cepheid mass with unprecedented accuracy. Up to now astronomers had two incompatible theoretical predictions of Cepheid masses. The new result shows that the prediction from stellar pulsation theory is spot on, while the prediction from stellar evolution theory is at odds with the new observations. The new results, from a team led by Grzegorz Pietrzyński (Universidad de Concepción, Chile, Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Poland), appear in the 25 November 2010 edition of the journal Nature. Grzegorz Pietrzyński introduces this remarkable result: "By using the HARPS instrument on the 3.6-metre telescope at ESO's La Silla Observatory in Chile, along with other telescopes, we have measured the mass of a Cepheid with an accuracy far greater than any earlier estimates. This new result allows us to immediately see which of the two competing theories predicting the masses of Cepheids is correct." Classical Cepheid Variables, usually called just Cepheids, are unstable stars that are larger and much brighter than the Sun [1]. They expand and contract in a regular way, taking anything from a few days to months to complete the cycle. The time taken to brighten and grow fainter again is longer for stars that are more luminous and shorter for the dimmer ones. This remarkably precise relationship makes the study of Cepheids one of the most effective ways to measure the distances to nearby galaxies and from there to map out the scale of the whole Universe [2]. Unfortunately, despite their importance, Cepheids are not fully understood. Predictions of their masses derived from the theory of pulsating stars are 20-30% less than predictions from the theory of the

  11. Loading protocols for single-implant crowns: a systematic review and meta-analysis.

    Science.gov (United States)

    Benic, Goran I; Mir-Mari, Javier; Hämmerle, Christoph H F

    2014-01-01

    To test whether or not immediate loading of single-implant crowns renders different results from early and conventional loading with respect to implant survival, marginal bone loss, stability of peri-implant soft tissue, esthetics, and patient satisfaction. An electronic search of Medline and Embase databases including studies published prior to August 1, 2012, was performed and complemented by a manual search. Randomized controlled trials (RCTs) comparing different loading protocols of single-implant crowns with a follow-up after restoration of at least 1 year were included. A meta-analysis yielded odds ratios (OR) and standardized mean differences (SMD) together with the corresponding 95% confidence intervals (95% CI). The search provided 10 RCTs comparing immediate and conventional loading and 1 RCT comparing immediate and early loading. When assessing the implant survival at 1 year of loading, the meta-analysis of 10 studies found no significant differences between immediate and conventional loading (OR = 0.75; 95% CI: 0.32 to 1.76). The total difference of marginal bone loss during the first year of function between immediate and conventional loading protocols in 7 RCTs did not reach statistical significance (SMD = -0.05 mm; 95% CI: -0.41 to 0.31 mm). There were no significant differences between immediate and conventional loading regarding implant survival and marginal bone loss at 2, 3, and 5 years of loading. Three RCTs comparing the change of papilla level between immediate and conventional loading identified no significant differences. One study investigated the recession of the buccal mucosa after implant placement and found significantly inferior soft tissue loss for immediate loading as compared to conventional loading. Two RCTs investigated the recession of the buccal mucosa after insertion of the definitive crown and found no differences between immediate and conventional loading. The esthetics and the patient satisfaction were assessed in one and

  12. Synchronization Model for Pulsating Variables

    Science.gov (United States)

    Takahashi, S.; Morikawa, M.

    2013-12-01

    A simple model is proposed, which describes the variety of stellar pulsations. In this model, a star is described as an integration of independent elements which interact with each other. This interaction, which may be gravitational or hydrodynamic, promotes the synchronization of elements to yield a coherent mean field pulsation provided some conditions are satisfied. In the case of opacity driven pulsations, the whole star is described as a coupling of many heat engines. In the case of stochastic oscillation, the whole star is described as a coupling of convection cells, interacting through their flow patterns. Convection cells are described by the Lorentz model. In both models, interactions of elements lead to various pulsations, from irregular to regular. The coupled Lorenz model also describes a light curve which shows a semi-regular variability and also shows a low-frequency enhancement proportional to 1/f in its power spectrum. This is in agreement with observations (Kiss et al. 2006). This new modeling method of ‘coupled elements’ may provide a powerful description for a variety of stellar pulsations.

  13. A statistical method for draft tube pressure pulsation analysis

    International Nuclear Information System (INIS)

    Doerfler, P K; Ruchonnet, N

    2012-01-01

    Draft tube pressure pulsation (DTPP) in Francis turbines is composed of various components originating from different physical phenomena. These components may be separated because they differ by their spatial relationships and by their propagation mechanism. The first step for such an analysis was to distinguish between so-called synchronous and asynchronous pulsations; only approximately periodic phenomena could be described in this manner. However, less regular pulsations are always present, and these become important when turbines have to operate in the far off-design range, in particular at very low load. The statistical method described here permits to separate the stochastic (random) component from the two traditional 'regular' components. It works in connection with the standard technique of model testing with several pressure signals measured in draft tube cone. The difference between the individual signals and the averaged pressure signal, together with the coherence between the individual pressure signals is used for analysis. An example reveals that a generalized, non-periodic version of the asynchronous pulsation is important at low load.

  14. SEE Transient Response of Crane Interpoint Single Output Point of Load DC-DC Converters

    Science.gov (United States)

    Sanders, Anthony B.; Chen, Dakai; Kim, Hak S.; Phan, Anthony M.

    2011-01-01

    This study was undertaken to determine the single event effect and transient susceptibility of the Crane Interpoint Maximum Flexible Power (MFP) Single Output Point of Load DC/DC Converters for transient interruptions in the output signal and for destructive and non destructive events induced by exposing it to a heavy ion beam..

  15. Computational model of miniature pulsating heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Mario J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Givler, Richard C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-01-01

    The modeling work described herein represents Sandia National Laboratories (SNL) portion of a collaborative three-year project with Northrop Grumman Electronic Systems (NGES) and the University of Missouri to develop an advanced, thermal ground-plane (TGP), which is a device, of planar configuration, that delivers heat from a source to an ambient environment with high efficiency. Work at all three institutions was funded by DARPA/MTO; Sandia was funded under DARPA/MTO project number 015070924. This is the final report on this project for SNL. This report presents a numerical model of a pulsating heat pipe, a device employing a two phase (liquid and its vapor) working fluid confined in a closed loop channel etched/milled into a serpentine configuration in a solid metal plate. The device delivers heat from an evaporator (hot zone) to a condenser (cold zone). This new model includes key physical processes important to the operation of flat plate pulsating heat pipes (e.g. dynamic bubble nucleation, evaporation and condensation), together with conjugate heat transfer with the solid portion of the device. The model qualitatively and quantitatively predicts performance characteristics and metrics, which was demonstrated by favorable comparisons with experimental results on similar configurations. Application of the model also corroborated many previous performance observations with respect to key parameters such as heat load, fill ratio and orientation.

  16. Immediate, early (3 weeks) and conventional loading (4 months) of single implants: Preliminary data at 1 year after loading from a pragmatic multicenter randomised controlled trial.

    Science.gov (United States)

    Grandi, Tommaso; Guazzi, Paolo; Samarani, Rawad; Tohme, Hani; Khoury, Samir; Sbricoli, Luca; Grandi, Giovanni; Esposito, Marco

    2015-01-01

    To compare the clinical outcome of single implants which underwent immediate nonocclusal loading with implants subjected to early non-occlusal loading at 3 weeks, and implants conventionally loaded at 4 months. One hundred and five patients in five private practices requiring a single implant-supported crown were randomised to immediate loading (35 patients), early loading (35 patients) and conventional loading (35 patients) groups. To be immediately or early loaded, implants had to be inserted with a torque superior to 45 Ncm. Immediately and early loaded implants received non-occluding temporary crows, whereas conventionally loaded implants were directly restored with definitive crowns. Temporary crowns were replaced by definitive ones after 4 months. Outcome measures were crown and implant failures, complications and peri-implant marginal bone level changes recorded by a blinded assessor. Two patients dropped out from the immediate loading group up to 1-year post-loading. Two implants failed, one in the immediately loaded and one in the early loaded group (P=0.601). One immediately loaded implant and two early loaded implants were affected by one complication each (P=0.162). Mean peri-implant marginal bone loss after 1 year was -0.120±0.230 mm (95% CI -0.35, 0.10) for immediate, -0.390±0.840 mm (95% CI -1.23, 0.45) for early and -0.201±0.306 mm (95% CI -0.51; 0.11) for conventionally loaded implants. There were no statistically significant differences for any of the outcome measures between the three loading strategies up to 1-year post-loading. No major clinical differences were observed with regard to implant survival, complications and marginal bone level changes when loading single implants immediately, early or conventionally.

  17. Load dependency in force-length relations in isolated single cardiomyocytes.

    Science.gov (United States)

    Iribe, Gentaro; Kaneko, Toshiyuki; Yamaguchi, Yohei; Naruse, Keiji

    2014-08-01

    The previously reported pressure-volume (PV) relationship in frog hearts shows that end-systolic PV relation (ESPVR) is load dependent, whereas ESPVR in canine hearts is load independent. To study intrinsic cardiac mechanics in detail, it is desirable to study mechanics in a single isolated cardiomyocyte that is free from interstitial connective tissue. Previous single cell mechanics studies used a pair of carbon fibers (CF) attached to the upper surface of opposite cell ends to stretch cells. These studies showed that end-systolic force-length (FL) relation (ESFLR) is load independent. However, the range of applicable mechanical load using the conventional technique is limited because of weak cell-CF attachment. Therefore, the behavior of ESFLR in single cells under physiologically possible conditions of greater load is not yet well known. To cover wider loading range, we contrived a new method to hold cell-ends more firmly using two pairs of CF attached to both upper and bottom surfaces of cells. The new method allowed stretching cells to 2.2 μm or more in end-diastolic sarcomere length. ESFLR virtually behaves in a load independent manner only with end-diastolic sarcomere length less than 1.95 μm. It exhibited clear load dependency with higher preload, especially with low afterload conditions. Instantaneous cellular elastance curves showed that decreasing afterload enhanced relaxation and slowed time to peak elastance, as previously reported. A simulation study of a mathematical model with detailed description of thin filament activation suggested that velocity dependent thin filament inactivation is crucial for the observed load dependent behaviors and previously reported afterload dependent change in Ca(2+) transient shape. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Tensile loading induced phase transition and rippling in single-layer MoS2

    Science.gov (United States)

    Bao, Hongwei; Huang, Yuhong; Yang, Zhi; Miao, Yaping; Chu, Paul K.; Xu, Kewei; Ma, Fei

    2017-05-01

    Molecular dynamics (MD) simulation is performed to study the structural evolution of single-layer MoS2 nanosheets under tensile loading and a phase transition from hexagonal structure to quadrilateral one is observed at a large strain when loaded along the zigzag direction but not along the armchair direction. Density functional theory (DFT) calculation illustrates that the newly generated quadrilateral phase is metallic. Further loading along the zigzag direction promotes an inhomogeneous distribution of lateral and shear stress around the phase boundaries due to local mechanical mismatch. As a result, periodic rippling parallel to the loading direction emerges and the wavelength and wave height change with strain according to λ∼ε-1/4 and h∼ε1/4. Accordingly, a graded distribution of strain can be produced or modulated by a simple tensile loading and the strategy might be utilized to enhance the photoelectrical properties of 2D materials and design strain-tunable nanodevices.

  19. Immediate Loading of Anterior Single Tooth Implants Placed in Healed Sites : Five-Year Results of a Randomized Clinical Trial

    NARCIS (Netherlands)

    den Hartog, Laurens; Raghoebar, Gerry M.; Stellingsma, Kees; Vissink, Arjan; Meijer, Henny J. A.

    2016-01-01

    Purpose: The aim of this study was to compare the 5-year outcome of immediate loading with that of conventional loading for anterior single-tooth implants placed in healed sites. It was hypothesized that immediate loading is not inferior to conventional loading. Materials and Methods: A total of 62

  20. Immediate loading of single SLA implants: drilling vs. osteotomes for the preparation of the implant site.

    Science.gov (United States)

    Stavropoulos, Andreas; Nyengaard, Jens R; Lang, Niklaus P; Karring, Thorkild

    2008-01-01

    To evaluate whether or not preparation of the implant site with osteotomes instead of drilling may improve peri-implant bone density and/or osseointegration, and whether or not this further improves the predictability of immediate loading of SLA implants. The second, third, and fourth premolars were extracted in both sides of the mandible in six dogs, and after at least 3 months four SLA implants were inserted into each side of the jaw. In three animals, the implant sites were prepared by means of osteotomes, while standard stepwise drilling was used in the remaining animals. In each side of the jaw, two non-adjacent implants were restored with single crowns 4 days after installation, while the remaining two implants were left without crowns to serve as non-loaded controls. After 2, 4, or 12 weeks of loading, specimens including the implants and surrounding tissues were obtained and processed for histologic analysis of undecalcified sections. All implants placed with osteotomes were lost (five before delivery of the crowns and the rest during the first week after loading). None of the conventionally inserted implants, however, was lost, and histomorphometrical analysis revealed similar soft- and hard peri-implant tissue characteristics at immediately loaded and non-loaded implants at all observation times. Average bone-to-implant contact was 59-72% at immediately loaded implants vs. 60-63% at non-loaded ones. Preparation of the implant site by means of osteotomes had a deleterious effect on osseointegration, while immediate loading of single, free-standing, SLA implants following a conventional surgical protocol did not jeopardize their osseointegration.

  1. Deterministic fabrication of dielectric loaded waveguides coupled to single nitrogen vacancy centers in nanodiamonds

    DEFF Research Database (Denmark)

    Siampour, Hamidreza; Kumar, Shailesh; Bozhevolnyi, Sergey I.

    We report on the fabrication of dielectric-loaded-waveguides which are excited by single-nitrogen-vacancy (NV) centers in nanodiamonds. The waveguides are deterministically written onto the pre-characterized nanodiamonds by using electron beam lithography of hydrogen silsesquioxane (HSQ) resist...... on silver-coated silicon substrate. Change in lifetime for NV-centers is observed after fabrication of waveguides and an antibunching in correlation measurement confirms that nanodiamonds contain single NV-centers....

  2. Immediate loading of single-tooth implants in the posterior region.

    Science.gov (United States)

    Abboud, Marcus; Koeck, Bernd; Stark, Helmut; Wahl, Gerhard; Paillon, Roswitha

    2005-01-01

    The aim of this study was to evaluate the clinical response and safety of immediately loaded single-tooth implants placed in the posterior region of the maxilla and mandible. Single-tooth implants were placed in healed extraction sites in 20 adult patients. Temporary pre-fabricated acrylic resin crowns were prepared and adjusted. The crown occlusion was adjusted to obtain minimal contacts in maximum intercuspation. After 6 weeks a ceramometal or all-ceramic crown was cemented. Radiographic and clinical examinations were made at baseline and at 3, 6, and 12 months. Cortical bone response and peri-implant mucosal responses were evaluated. The marginal bone level at the time of implant placement was preserved. The mean change in marginal bone level was 0.01 mm at 12 months. The mean Periotest value after 360 days was -4. The peri-implant mucosal adaptation to the anatomic form of the provisional crown resulted in a natural esthetic outcome, and a gain in papilla length was observed. One implant failure was recorded because of provisional luting cement impaction. Clinical research has shown that immediate loading is a possible treatment modality. The immediate functional loading of implants placed in this study resulted in bone adaptation to loading. A satisfactory success rate with positive tissue responses was achieved. The results of this limited investigation indicated that immediate loading of unsplinted single-tooth implants in the posterior region may be a viable treatment option with an esthetic outcome.

  3. [Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Meijers, C.C.A.J.; Vergoossen, E.L.; Creugers, N.H.J.

    2014-01-01

    The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and

  4. [Loading and strength of single- and multi-unit fixed dental prostheses 2. Strength

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Meijers, C.C.A.J.; Vergoossen, E.L.; Creugers, N.H.J.

    2014-01-01

    The ultimate strength of a dental prosthesis is defined as the strongest loading force applied to the prosthesis until afracture failure occurs. Important key terms are strength, hardness, toughness and fatigue. Relatively prevalent complications of single- and multi-unit fixed dental prostheses are

  5. Modelling of Vortex-Induced Loading on a Single-Blade Installation Setup

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac; Heinz, Joachim Christian

    2016-01-01

    Vortex-induced integral loading fluctuations on a single suspended blade at various inflow angles were modeled in the presents work by means of stochastic modelling methods. The reference time series were obtained by 3D DES CFD computations carried out on the DTU 10MW reference wind turbine blade...

  6. Immediate, early (6 weeks) and delayed loading (3 months) of single implants: 4-month 
post-loading from a multicenter pragmatic randomised controlled trial.

    Science.gov (United States)

    Esposito, Marco; Siormpas, Konstantinos; Mitsias, Miltiadis; Bechara, Soheil; Trullenque-Eriksson, Anna; Pistilli, Roberto

    To compare the clinical outcome of single, partial and full fixed implant-supported prostheses immediately loaded (within 48 h), early loaded at 6 weeks and conventionally loaded at 3 months (delayed loading). Eighty-one patients (27 requiring single implants, 27 requiring partial fixed prostheses and 27 requiring total fixed cross-arch prostheses) were randomised in equal numbers in three private practices to immediate loading (27 patients), early loading (27 patients) and conventional loading (27 patients) according to a parallel group design with three arms. To be immediately or early loaded, implants had to be inserted with a torque superior to 40 Ncm. Implants were initially loaded with provisional prostheses and replaced after 4 months by definitive ones. Outcome measures were prosthesis and implant failures and complications. No patient dropped out up to 4-months post-loading. No implant or prosthesis failed or any complications occurred. All loading strategies were highly successful and no differences could be observed for implant survival and complications when loading implants immediately, early or conventionally. Conflict-of-interest statement: This trial was partially funded by MegaGen, the manufacturer of the implants evaluated in this investigation, however data belonged to the authors and by no means did the manufacturer interfere with the conduct of the trial or the publication of its results.

  7. Progress of cryogenic pulsating heat pipes at UW-Madison

    Science.gov (United States)

    Diego Fonseca, Luis; Mok, Mason; Pfotenhauer, John; Miller, Franklin

    2017-12-01

    Space agencies continuously require innovative cooling systems that are lightweight, low powered, physically flexible, easily manufactured and, most importantly, exhibit high heat transfer rates. Therefore, Pulsating Heat Pipes (PHPs) are being investigated to provide these requirements. This paper summarizes the current development of cryogenic Pulsating Heat Pipes with single and multiple evaporator sections built and successfully tested at UW-Madison. Recently, a helium based Pulsating Heat Pipe with three evaporator and three condenser sections has been operated at fill ratios between 20 % and 80 % operating temperature range of 2.9 K to 5.19 K, resulting in a maximum effective thermal conductivity up to 50,000 W/m-K. In addition, a nitrogen Pulsating Heat Pipe has been built with three evaporator sections and one condenser section. This PHP achieved a thermal performance between 32,000 W/m-K and 96,000 W/m-K at fill ratio ranging from 50 % to 80 %. Split evaporator sections are very important in order to spread cooling throughout an object of interest with an irregular temperature distribution or where multiple cooling locations are required. Hence this type of configurations is a proof of concept which hasn’t been attempted before and if matured could be applied to cryo-propellant tanks, superconducting magnets and photon detectors.

  8. Geomagnetic Pulsations-Production/Interpretation.

    Science.gov (United States)

    1982-09-01

    determine the shapes of the period distributions. When resonance curves for RLC circuits having various Q values were fitted to period distributions ob...resonances would not, therefore, have been avpreciably altered by the band- pass filters. The RLC circuits wore used for convenience in the calculation of...whether they might furnish any definitely contrad ctory evidence. The resonant periods of the pulsations analyzed under this grant have consistently

  9. Head pulsations in a centrifugal pump

    Science.gov (United States)

    Boiko, V. S.; Sotnyk, M. I.; Moskalenko, V. V.

    2017-08-01

    This article investigated the factors, which affect to the character of the head pulsations of a centrifugal pump. We investigated the dependence of the shape and depth of these pulsations from the operation mode of the pump. Was determined, that the head pulsations at the outlet of the impeller (pulsations on the blade passing frequency) cause head pulsations at the outlet of the pump, that have the same frequency, but differ in shape and depth. These pulsations depend on the design features of the flow-through part of the pump (from the ratio of hydraulic losses on the friction and losses on the vortex formation). A feature of the researches that were conducted is also the using of not only hydraulic but also electric modeling methods. It allows determining the values of the components of hydraulic losses.

  10. Amplitude Modulation of Pulsation Modes in Delta Scuti Stars

    Science.gov (United States)

    Bowman, Dominic M.

    2017-10-01

    The pulsations in δ Sct stars are excited by a heat engine driving mechanism caused by increased opacity in their surface layers, and have pulsation periods of order a few hours. Space based observations in the last decade have revealed a diverse range of pulsational behaviour in these stars, which is investigated using an ensemble of 983 δ Sct stars observed continuously for 4 yr by the Kepler Space Telescope. A statistical search for amplitude modulation of pulsation modes is carried out and it is shown that 61.3 per cent of the 983 δ Sct stars exhibit significant amplitude modulation in at least a single pulsation mode, and that this is uncorrelated with effective temperature and surface gravity. Hence, the majority of δ Sct stars exhibit amplitude modulation, with time-scales of years and longer demonstrated to be significant in these stars both observationally and theoretically. An archetypal example of amplitude modulation in a δ Sct star is KIC 7106205, which contains only a single pulsation mode that varies significantly in amplitude whilst all other pulsation modes stay constant in amplitude and phase throughout the 4-yr Kepler data set. Therefore, the visible pulsational energy budget in this star, and many others, is not conserved over 4 yr. Models of beating of close-frequency pulsation modes are used to identify δ Sct stars with frequencies that lie closer than 0.001 d^{-1}, which are barely resolved using 4 yr of Kepler observations, and maintain their independent identities over 4 yr. Mode coupling models are used to quantify the strength of coupling and distinguish between non-linearity in the form of combination frequencies and non-linearity in the form of resonant mode coupling for families of pulsation modes in several stars. The changes in stellar structure caused by stellar evolution are investigated for two high amplitude δ Sct (HADS) stars in the Kepler data set, revealing a positive quadratic change in phase for the fundamental and

  11. Online short-term heat load forecasting for single family houses

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

    2013-01-01

    This paper presents a method for forecasting the load for heating in a single-family house. Both space and hot tap water heating are forecasted. The forecasting model is built using data from sixteen houses in Sønderborg, Denmark, combined with local climate measurements and weather forecasts....... Every hour the hourly heat load for each house the following two days is forecasted. The forecast models are adaptive linear time-series models and the climate inputs used are: ambient temperature, global radiation, and wind speed. A computationally efficient recursive least squares scheme is used...

  12. BUCKLING BEHAVIOUR OF SINGLE-WALLED CARBON NANOTUBES UNDER AXIAL LOADING

    Directory of Open Access Journals (Sweden)

    Grzegorz Litak

    2017-03-01

    Full Text Available We investigate a single walled Carbon Nanotube under an axially directed compressive line loading applied at both of its edges. The expected buckling behavior we study by application of a molecular computation approach. We formulate a global potential and search for its minimum to obtain the equilibrium configuration. Using besides the main parameter, which is the value of the loading, as second parameter the diameter of the tube, we are able to define the critical value of the diameter, for which we obtain the coincident case of local shell buckling.

  13. Load Rate Effects in Adhesive Single Lap Joints Bonded with Epoxy/Ceramic Composites

    Directory of Open Access Journals (Sweden)

    Heraldo da Costa Mattos

    Full Text Available Abstract The present paper is concerned with the analysis of the effect of the loading rate in a particular class of single lap joints used in the oil industry. The adhesive/adherend system consists of ASTM A36 steel plates bonded with an epoxy/ceramic composite. The loading rate sensitivity is analysed considering two different situations: (i strain controlled quasi-static rupture tests and (ii applications in which the joint may oscillate like a spring. This second situation is motivated by a specific application: the transport of an ethanol reservoir by a crane using a special truss lifting system attached to the tank through bonded joints. Quasi-static tensile tests allow observing a rate-dependent behaviour of the joint with higher strengths for higher cross-head velocities. An algebraic equation is proposed to predict the dependence of the rupture force on the elongation rate in tensile tests and the model predictions are in good agreement with experimental results. However, in the case of the transport of a tank with mass M (situation (ii, the lifting system cannot be only designed to resist the static load (the weight. Fast loading may induce vibration. Like in a spring-mass system, even a very small oscillation of the joint induces a dynamic load that is higher than the static load. A simple analysis allows proposing conditions for a safe operation in this case.

  14. 3D Finite Element Modeling of Single Bolt Connections under Static and Dynamic Tension Loading

    Directory of Open Access Journals (Sweden)

    Emily Guzas

    2015-01-01

    Full Text Available The Naval Undersea Warfare Center has funded research to examine a range of finite element approaches used for modeling bolted connections subjected to various loading conditions. Research focused on developing finite element bolt representations that were accurate and computationally efficient. A variety of finite element modeling approaches, from detailed models to simplified ones, were used to represent the behavior of single solid bolts under static and dynamic tension loading. Test cases utilized models of bolted connection test arrangements (static tension and dynamic tension developed for previous research and validated against test data for hollow bore bolts (Behan et al., 2013. Simulation results for solid bolts are validated against experimental data from physical testing of bolts in these load configurations.

  15. Immediate functional loading of implants in single tooth replacement: a prospective clinical multicenter study.

    Science.gov (United States)

    Donati, Mauro; La Scala, Vincenzo; Billi, Mauro; Di Dino, Biagio; Torrisi, Paolo; Berglundh, Tord

    2008-08-01

    The aim of the present study was to evaluate the outcome of immediate functional loading of implants in single-tooth replacement using two different installation procedures. One hundred and fifty-one subjects, who required single-tooth rehabilitation in the area of 15-25 and 35-45, were enrolled in eight private clinics in Italy. The implant sites were randomly allocated to one of the following treatment groups. In the control group, in which a standard preparation procedure for implant placement and submerged healing of the implant was used, abutment connection and loading of the implants were performed 3 months after installation. In the test group 1, a standard preparation procedure for the implant placement and immediate functional loading of implant was carried out. In the test 2 group, however, a modified implant installation procedure (osteotome technique) was used followed by immediate functional loading of the implant. Clinical and radiographic examinations were performed at 3 and 12 months of follow-up at all sites. Three implants (5.5%) from the test 2 group (osteotome preparation) and one (2%) from the test 1 group (conventional drill preparation) failed to integrate and were removed one and three months after implant installation. The mean marginal bone loss assessed at 12 months was 0.31 mm (test 1), 0.25 mm (test 2) and 0.38 mm (control) (no statistically significant differences were found between the three treatment groups.) It is suggested that immediate functional loading of implants that are placed with a conventional installation technique and with sufficient primary stability may be considered as a valid treatment alternative in a single-tooth replacement.

  16. An Analytical Method for Determining the Load Distribution of Single-Column Multibolt Connection

    Directory of Open Access Journals (Sweden)

    Nirut Konkong

    2017-01-01

    Full Text Available The purpose of this research was to investigate the effect of geometric variables on the bolt load distributions of a cold-formed steel bolt connection. The study was conducted using an experimental test, finite element analysis, and an analytical method. The experimental study was performed using single-lap shear testing of a concentrically loaded bolt connection fabricated from G550 cold-formed steel. Finite element analysis with shell elements was used to model the cold-formed steel plate while solid elements were used to model the bolt fastener for the purpose of studying the structural behavior of the bolt connections. Material nonlinearities, contact problems, and a geometric nonlinearity procedure were used to predict the failure behavior of the bolt connections. The analytical method was generated using the spring model. The bolt-plate interaction stiffness was newly proposed which was verified by the experiment and finite element model. It was applied to examine the effect of geometric variables on the single-column multibolt connection. The effects were studied of varying bolt diameter, plate thickness, and the plate thickness ratio (t2/t1 on the bolt load distribution. The results of the parametric study showed that the t2/t1 ratio controlled the efficiency of the bolt load distribution more than the other parameters studied.

  17. Immediate Replacement of Single Teeth With Immediately Loaded Implants: Retrospective Analysis of a Clinical Case Series.

    Science.gov (United States)

    Sethi, Ashok; Kaus, Thomas

    2017-02-01

    The purpose of this retrospective analysis of clinical data was to evaluate the predictability of replacing failing single teeth with immediately placed implants loaded via a transitional (provisional) restoration. Implants were placed immediately at the time of extraction of failing single teeth that met predetermined inclusion criteria. A detailed protocol was followed to enable immediate loading of the implant with the use of prefabricated abutments in combination with transitional restorations. A total of 375 immediate implants had been placed in 274 patients and loaded immediately. With the certainty of 95%, an estimated overall mean survival rate better than 97.6% was observed after a mean observation period of 36 months. The maximum observation period was 142 months. Four implants had been lost in function. Immediate loading of immediately placed implants is a possible treatment option that might be predictably and successfully achieved. Implants of adequate primary stability coupled with a range of prefabricated abutments permit function to be achieved using transitional restorations. The preliminary results of this clinical case series are very promising.

  18. Non-spherical voids and lattice reorientation patterning in a shock-loaded Al single crystal

    DEFF Research Database (Denmark)

    Hong, Chuanshi; Fæster, Søren; Hansen, Niels

    2017-01-01

    An Al single crystal shock loaded in the direction and captured at incipient spallation was examined by combining X-ray tomography, electron backscatter diffraction on a scanning electron microscope, and transmission electron microscopy (TEM). Octahedral voids with {1 1 1} faces were...... of the observed reorientation patterns based on active slip systems rationalizes the key features observed and suggests that the systematic reorientation patterns result from the dominance of a single slip system in each individual zone. Microstructures revealed by TEM in the spall region show formation...

  19. Partial Shading Detection in Solar System Using Single Short Pulse of Load

    Directory of Open Access Journals (Sweden)

    Bartczak Mateusz

    2017-03-01

    Full Text Available A single photovoltaic panel under uniform illumination has only one global maximum power point, but the same panel in irregularly illuminated conditions can have more maxima on its power-voltage curve. The irregularly illuminated conditions in most cases are results of partial shading. In the work a single short pulse of load is used to extract information about partial shading. This information can be useful and can help to make some improvements in existing MPPT algorithms. In the paper the intrinsic capacitance of a photovoltaic system is used to retrieve occurrence of partial shading.

  20. Evaluation of runner cone extension to dampen pressure pulsations in a Francis model turbine

    Science.gov (United States)

    Gogstad, Peter Joachim; Dahlhaug, Ole Gunnar

    2016-11-01

    Today's energy market has a high demand of flexibility due to introduction of other intermittent renewables as wind and solar. To ensure a steady power supply, hydro turbines are often forced to operate more at part load conditions. Originally, turbines were built for steady operation around the best efficiency point. The demand of flexibility, combined with old designs has showed an increase in turbines having problems with hydrodynamic instabilities such as pressure pulsations. Different methods have been investigated to mitigate pressure pulsations. Air injection shows a significant reduction of pressure pulsation amplitudes. However, installation of air injection requires extra piping and a compressor. Investigation of other methods such as shaft extension shows promising results for some operational points, but may significantly reduce the efficiency of the turbine at other operational points. The installation of an extension of the runner cone has been investigated at NTNU by Vekve in 2004. This has resulted in a cylindrical extension at Litjfossen Power Plant in Norway, where the bolt suffered mechanical failure. This indicates high amplitude pressure pulsations in the draft tube centre. The high pressure pulsation amplitudes are believed to be related to high tangential velocity in the draft tube. The mentioned runner cone extension has further been developed to a freely rotating extension. The objective is to reduce the tangential velocity in the draft tube and thereby the pressure pulsation amplitudes.

  1. Pulsating X-ray sources

    International Nuclear Information System (INIS)

    Trumper, J.

    1986-01-01

    The discovery of pulsating X-ray sources in close binary systems was one of the major achievements of the Uhuru satellite. Today one knows about two dozens of these sources with pulsational periods between 69 ms and 835 s. In most cases the X-ray source orbits an early-type star of high mass having a rather large optical luminosity. There are a few exceptions: GX1+4 is associated with a late-type (M6) giant, 4U1616-67 has a comparison of very low mass (≤ 0.1 M/sub sub solar/), and Her X-1 is a borderline case, since its counterpart HZ Her is an A-F star of -- 2/sub sub solar/. It is clear that the X-ray sources in these systems are rotating magnetized neutron stars accreting from their normal companion, probably in most cases via Roche lobe overflow which leads to the formation of an accretion disk. In some cases (e.g. Vela X-1) the accretion proceeds via a stellar wind. Pulsations occur because in the immediate vicinity of the neutron star the matter is funneled by the strong magnetic field onto the polar caps where a hot and very luminous plasma is formed. Typical luminosities are huge, namely of the order of 10/sup 37/ erg/s which are radiated at effective temperatures of -- 10/sup 8/ K. Much has been learned about these systems and about neutron stars from studies of pulse arrival times and source spectra. The author briefly summarizes some of the major results and discusses some very recent results obtained with EXOSAT

  2. Immediate Loading of Single Implants: A 2-Year Prospective Multicenter Study.

    Science.gov (United States)

    Mangano, Carlo; Raes, Filiep; Lenzi, Carolina; Eccellente, Tammaro; Ortolani, Michele; Luongo, Giuseppe; Mangano, Francesco

    The aim of this prospective multicenter study was to evaluate the outcomes of single implants subjected to immediate functional loading. Inclusion criteria were single-tooth placement in postextraction sockets or fully healed sites, and sufficient bone height and width to place an implant of at least 3.5 × 10.0 mm. All implants were functionally loaded immediately after placement and followed for 2 years. Outcome measures were implant survival, complications, and peri-implant marginal bone loss (MBL). A total of 57 implants (38 maxilla, 19 mandible) were placed in 46 patients (23 men, 23 women, aged 18-73 years). Of these, 10 implants were placed in postextraction sockets. One implant failed, in a healed site, giving a patient-based overall 2-year survival rate of 97.6%. The incidence of biologic complications was 1.8%; prosthetic complications amounted to 7.5%. The peri-implant MBL was 0.37 ± 0.22 mm (healed sites: 0.4 mm ± 0.22; postextraction sockets: 0.3 mm ± 0.22). The immediate functional loading of single implants seems to represent a safe and successful procedure. Long-term follow-up studies on a larger sample of patients are needed to confirm these results.

  3. Self-pulsation in Raman fiber amplifiers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard; Ott, Johan Raunkjær; Rottwitt, Karsten

    2009-01-01

    Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated.......Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated....

  4. Models of cylindrical bubble pulsation.

    Science.gov (United States)

    Ilinskii, Yurii A; Zabolotskaya, Evgenia A; Hay, Todd A; Hamilton, Mark F

    2012-09-01

    Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23-26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion.

  5. Single-stage revision for periprosthetic hip infection using antibiotic loaded impaction graft.

    Science.gov (United States)

    Ebied, Ayman M; Elseedy, Adel I; Gamal, Osama

    2016-11-10

    Staged revision for periprosthetic infection of the hip is an accepted and widely used technique by many surgeons. However, single-stage exchange of the hip prosthesis remains an attractive option to others because of the advantages of reduced morbidity, shorter treatment time and hospital stay in addition to the reduced cost of treatment. Single-stage revision for periprosthetic hip infection can achieve excellent results if a specific protocol for patients' selection and management is followed. 52 patients with evidence of periprosthetic infection had preoperative aspiration of the affected hip. The infecting organisms were identified in 33/52 and single-stage revision was performed. The remaining 19 patients had a 2-stage exchange arthroplasty. Patients in the single-stage revision protocol had antibiotic loaded morsellized bone graft, a cemented cup and a long cementless stem. At an average follow up of 6 (range 4-8) years postoperatively, only 1 case of persistent infection was found in the single-stage group - a 97% rate of eradicating infection was achieved. Single-stage exchange achieves excellent success rate in patients with periprosthetic infection when a specific protocol for patient selection and management is followed.

  6. Large Deflections Mechanical Analysis of a Suspended Single-Wall Carbon Nanotube under Thermoelectrical Loading

    Directory of Open Access Journals (Sweden)

    Assaf Ya'akobovitz

    2011-01-01

    Full Text Available Following the recent progress in integrating single-wall carbon nanotubes (SWCNTs into silicon-based micro-electromechanical systems (MEMS, new modeling tools are needed to predict their behavior under different loads, including thermal, electrical and mechanical. In the present study, the mechanical behavior of SWCNTs under thermoelectrical loading is analyzed using a large deflection geometrically nonlinear string model. The effect of the resistive heating was found to have a substantial influence on the SWCNTs behavior, including significant enhancement of the strain (up to the millistrains range and buckling due to the thermal expansion. The effect of local buckling sites was also studied and was found to enhance the local strain. The theoretical and numerical results obtained in the present study demonstrate the importance of resistive heating in the analysis of SWCNTs and provide an additional insight into the unique mechanics of suspended SWCNTs.

  7. Pulsative hematoma: A penile fracture complication

    Directory of Open Access Journals (Sweden)

    Nale Đorđe

    2007-01-01

    Full Text Available Background. Fracture of the penis is a direct blunt trauma of the erect or semi-erect penis. It can be treated by conservative or surgical means. Retrospective analyses of conservative penile fracture treatment reveal frequent immediate and later complications. Case report. We presented a 41- year-old patient with pulsative hematoma caused by an unusual fracture of the penis. Fracture had appeared 40 days before the admittance during a sexual intercourse. The patient was treated surgically. Conclusion. Pulsative hematoma (pulsative diverticulum is a very rare, early complication of a conservatively treated penile fracture. Surgical treatment has an advantage over surgical one, which was confirmed by our case report.

  8. Interface debond crack growth in tension–tension cyclic loading of single fiber polymer composites

    DEFF Research Database (Denmark)

    Pupurs, Andrejs; Goutianos, Stergios; Brøndsted, Povl

    2013-01-01

    Fiber/matrix interface debond crack growth from a fiber break is defined as one of the key mechanisms of fatigue damage in unidirectional composites. Considering debond as an interface crack its growth in cyclic loading is analyzed utilizing a power law, where the debond growth rate is a power...... for glass fiber/epoxy single fiber composites. Analytical method in the steady-state growth region and FEM for short debonds are combined for calculating the strain energy release rate of the growing debond crack. Interface failure parameters in fatigue are determined by fitting the modeling...

  9. Mechanical performance of a screw-type veterinary suture anchor subjected to single load to failure and cyclic loads.

    Science.gov (United States)

    Balara, Jason M; McCarthy, Robert J; Boudrieau, Randy J; Kraus, Karl H

    2004-01-01

    To characterize the mechanical performance of a veterinary bone anchor under static and cyclic loads. Mechanical testing study. Cadaveric canine humeri. Humeri (6 pairs) were collected from skeletally mature dogs (mean [+/-SD] age, 17.2+/-2.1 months; weight, 20.8+/-1.5 kg). Bone anchors were inserted in the proximal metaphysis using nylon, and were longitudinally extracted. For the opposite humerus, anchors were subjected to longitudinal cyclic load (50% of the load at failure of their pair) for 1200 cycles then longitudinally loaded to failure. Anchors were then installed in a similar and adjacent area of these 2(nd) humeri with nylon and cyclically tested perpendicular to the axis of anchor insertion (100% of the longitudinal holding power of their pair) for 1200 cycles, then perpendicularly loaded to failure. Paired t-tests were used to compare holding power before and after longitudinal cyclic testing. Longitudinal holding power of the screw-type anchor in the proximal humerus was 385+/-30 N. Anchor pullout was the only mode of failure. Anchors in the paired humeri did not fail after 1200 cycles of 50% longitudinal loading, and post-cycle holding strength was not different (335+/-87 N; P=.32). Perpendicularly loaded anchors did not fail after 1200 cycles of 100% of opposite longitudinal holding strength, and had post-cycle perpendicular holding strengths of 514+/-72 N. Suture breakage was the mode of failure. Bone anchor holding strength is dependent on orientation of suture load. Screw-type bone anchor holding strength was not affected by longitudinal cyclic loading, and holding strengths of approximately 385 N can be expected in metaphyseal bone of large-breed mature dogs. Perpendicularly loaded anchors have higher failure loads, and holding strength of approximately 514 N can be expected in metaphyseal bone of the proximal humerus.

  10. Enhanced procollagen processing in skeletal muscle after a single bout of eccentric loading in humans

    DEFF Research Database (Denmark)

    Crameri, Regina M; Langberg, Henning; Teisner, Børge

    2004-01-01

    young healthy male subjects performed a single bout of unaccustomed high intensity eccentric exercise on one leg, with the contralateral leg being the control. A significant increase in the muscle interstitial concentration of the N-terminal propeptide of procollagen type I (PINP) was observed (day 0: 1......-terminal propeptide of procollagen type III (PIIINP) was also shown in the exercising leg only. Further, from day 2 post-exercise, immunoreactivity for tenascin C and reactive macrophages (CD68+ cells) was seen within the perimysial and endomysial connective tissue of the exercising leg only, indicating a high...... mechanical load and inflammation. This study shows that following a single bout of high intensity eccentric exercise there is an increase in procollagen processing within skeletal muscle in humans....

  11. Single-leg landing neuromechanical data following load and land height manipulations

    Directory of Open Access Journals (Sweden)

    Andrew D. Nordin

    2016-09-01

    Full Text Available Lower extremity sagittal kinematic and kinetic data are summarized alongside electrical muscle activities during single-leg landing trials completed in contrasting external load and landing height conditions. Nineteen subjects were analyzed during 9 landing trials in each of 6 experimental conditions computed as percentages of subject anthropometrics (bodyweight: BW and subject height: H; BW, BW+12.5%, BW+25%, and H12.5%, H25%. Twelve lower extremity variables (sagittal hip, knee, ankle angles and moments, vertical ground reaction force (GRFz, gluteus maximus, biceps femoris, vastus medials, medial gastrocnemius, and tibialis anterior muscles were assessed using separate principal component analyses (PCA. Variable trends across conditions were summarized in “Neuromechanical synergies in single-leg landing reveal changes in movement control. Human Movement Science” (Nordin and Dufek, 2016 [1], revealing changes in landing biomechanics and movement control.

  12. Load requirements for maintaining structural integrity of Hanford single-shell tanks during waste feed delivery and retrieval activities

    International Nuclear Information System (INIS)

    JULYK, L.J.

    1999-01-01

    This document provides structural load requirements and their basis for maintaining the structural integrity of the Hanford Single-Shell Tanks during waste feed delivery and retrieval activities. The requirements are based on a review of previous requirements and their basis documents as well as load histories with particular emphasis on the proposed lead transfer feed tanks for the privatized vitrification plant

  13. Load requirements for maintaining structural integrity of Hanford single-shell tanks during waste feed delivery and retrieval activities

    Energy Technology Data Exchange (ETDEWEB)

    JULYK, L.J.

    1999-09-22

    This document provides structural load requirements and their basis for maintaining the structural integrity of the Hanford Single-Shell Tanks during waste feed delivery and retrieval activities. The requirements are based on a review of previous requirements and their basis documents as well as load histories with particular emphasis on the proposed lead transfer feed tanks for the privatized vitrification plant.

  14. Gas Pulsation Control by a Shunt Pulsation Trap with Perforated Tubes and an Optional Absorptive Silencer

    OpenAIRE

    Huang, Paul Xiubao; Yonkers, Sean; Hokey, David

    2016-01-01

    This paper is a continuing work from the same authors on the same topic of gas pulsation control using a shunt pulsation trap method by Huang (2012a, 2014). Traditionally, a serial pulsation dampener/muffler, often a reactive type, is connected AFTER the discharge of a positive displacement compressor or engine. It is capable of reducing pressure pulsation level up to 10-20 folds or 20-40 dB but is bulky and suffers sizable back pressure losses. It has been demonstrated in the previous theore...

  15. MEMS measurements of single cell stiffness decay due to cyclic mechanical loading.

    Science.gov (United States)

    Barazani, Bruno; Warnat, Stephan; MacIntosh, Andrew J; Hubbard, Ted

    2017-08-25

    The goal of this study was to measure the mechanical stiffness of individual cells and to observe changes due to the application of repeated cell mechanical loads. 28 single baker's yeast cells (Saccharomyces cerevisiae) were fatigue tested and had their stiffness measured during repetitive loading cycles performed by a MEMS squeezer in aqueous media. Electrothermal micro-actuators compressed individual cells against a reference back spring; cell and spring motions were measured using a FFT image analysis technique with ~10 nm resolution. Cell stiffness was calculated based on measurements of cell elongation vs. applied force which resulted in stiffness values in the 2-10 N/m range. The effect of increased force was studied for cells mechanically cycled 37 times. Cell stiffness decreased as the force and the cycle number increased. After 37 loading cycles (~4 min), forces of 0.24, 0.29, 0.31, and 0.33 μN caused stiffness drops of 5%, 13%, 31% and 41% respectively. Cells force was then set to 0.29 μN and cells were tested over longer runs of 118 and 268 cycles. After 118 cycles (~12 min) cells experienced an average stiffness drop of 68%. After 268 cycles (~25 min) cells had a stiffness drop of 77%, and appeared to reach a stiffness plateau of 20-25% of the initial stiffness after approximately 200 cycles.

  16. Modeling Laterally Loaded Single Piles Accounting for Nonlinear Soil-Pile Interactions

    Directory of Open Access Journals (Sweden)

    Maryam Mardfekri

    2013-01-01

    Full Text Available The nonlinear behavior of a laterally loaded monopile foundation is studied using the finite element method (FEM to account for soil-pile interactions. Three-dimensional (3D finite element modeling is a convenient and reliable approach to account for the continuity of the soil mass and the nonlinearity of the soil-pile interactions. Existing simple methods for predicting the deflection of laterally loaded single piles in sand and clay (e.g., beam on elastic foundation, p-y method, and SALLOP are assessed using linear and nonlinear finite element analyses. The results indicate that for the specific case considered here the p-y method provides a reasonable accuracy, in spite of its simplicity, in predicting the lateral deflection of single piles. A simplified linear finite element (FE analysis of piles, often used in the literature, is also investigated and the influence of accounting for the pile diameter in the simplified linear FE model is evaluated. It is shown that modeling the pile as a line with beam-column elements results in a reduced contribution of the surrounding soil to the lateral stiffness of the pile and an increase of up to 200% in the predicted maximum lateral displacement of the pile head.

  17. Immediate loading of post-extractive single-tooth implants: a 1-year prospective study.

    Science.gov (United States)

    Cristalli, Maria Paola; Marini, Roberta; La Monaca, Gerardo; Sepe, Claudio; Tonoli, Federica; Annibali, Susanna

    2015-09-01

    The aim of this prospective clinical trial was to assess clinical, radiological, and esthetic outcomes of immediate-loaded post-extractive implants after 1 year of follow-up. Twenty-four consecutive patients (15 females and nine males) with a mean age of 47.27 years (range 35-65) requiring single-tooth extraction in the maxillary or mandibular anterior or premolar areas were enrolled. Twenty-five NobelActive implants (Nobel Biocare, Göteborg, Sweden) were placed and loaded immediately after tooth extraction. The definitive prosthetic restoration was delivered 6 months later. Clinical parameters, marginal bone loss, as well as, pink and white esthetic scores (PES and WES) were evaluated at 3, 6, and 12 months after implant placement. After 12-month follow-up period, a success rate of 91.67% was reported: Two of the 25 initially placed implants were lost after 4 weeks due to lack of osseointegration. The mean marginal bone loss after 1-year follow-up was 0.383 (SD ± 0.749) at mesial site and 0.278 (SD ± 0.595) at distal site. No statistically significant changes in the full-mouth plaque score (FMPS) and in the full-mouth bleeding score (FMBS) were observed from baseline to 12 months. The mean total PES/WES was 17.13 ± 1.91 (range: 13-20). None of 23 implants had an overall score immediate placement and loading of a single NobelActive(™) implant in a fresh extraction socket may be considered a valuable and predictable option in terms of implant success as well as hard and soft tissues stability. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. [Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance].

    Science.gov (United States)

    de Baat, C; Witter, D J; Meijers, C C A J; Vergoossen, E L M; Creugers, N H J

    2014-03-01

    The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and metal-ceramic single-unit fixed dental prosthesis is determined by the configuration's convergence angle, the height, the volume, the interocclusal space, the cervical outline design, the additional preparations, the quality of the (build-up) restoration, and the surface roughness. A silicate ceramic single-unit fixed dental prosthesis is attached through adhesion using a composite cement, but the retention and resistance of an oxide ceramic single-unit fixed dental prosthesis is dependent on the abutment tooth configuration. Most types of multi-unit fixed dental prosthesis have the following additional retention and resistance determining factors: the position in the occlusal system, the number of abutment teeth and their mutual configurations, and the length of (cantilever) pontics. A resin-bonded fixed partial denture's retention and resistance are determined by its bonding as well as its enamel surface coverage and its resistance preparations.

  19. Radial pulsations in DB white dwarfs?

    Science.gov (United States)

    Kawaler, Steven D.

    1993-01-01

    Theoretical models of DB white dwarfs are unstable against radial pulsation at effective temperatures near 20,000-30,000 K. Many high-overtone modes are unstable, with periods ranging from 12 s down to the acoustic cutoff period of approximately 0.1 s. The blue edge for radial instability lies at slightly higher effective temperatures than for nonradial pulsations, with the temperature of the blue edge dependent on the assumed efficiency of convection. Models with increased convective efficiency have radial blue edges that are increasingly closer to the nonradial blue edge; in all models the instability persists into the nonradial instability strip. Radial pulsations therefore may exist in the hottest DB stars that lie below the DB gap; the greatest chance for detection would be observations in the ultraviolet. These models also explain why searches for radial pulsations in DA white dwarfs have failed: the efficient convection needed to explain the blue edge for nonradial DA pulsation means that the radial instability strip is 1000 K cooler than found in previous investigations. The multiperiodic nature of the expected pulsations can be used to advantage to identify very low amplitude modes using the uniform spacing of the modes in frequency. This frequency spacing is a direct indicator of the mass of the star.

  20. Pulsations of Energetic Electron Pulsations In Association With Substorm Onset

    Science.gov (United States)

    Åsnes, A.; Stadsnes, J.; Bjordal, J.; Østgaard, N.; Haaland, S.; Rosenberg, T. J.; Detrick, D. L.

    The Polar Ionospheric X-ray Imaging Experiment (PIXIE) is giving detailed images of the energetic electron precipitation when the POLAR satellite is near perigee over the Antarctica. In this area the PIXIE images have a spatial resolution of the order of 100 km, and a temporal resolution of 10 s can be obtained. In this paper we present the results of a study focusing on the onset and expansion of a substorm occuring on July 24, 1998. In this event we observe strong modulations of the energetic electron precipitation with period around 1 minute following substorm onset. The pulsations were restricted to a narrow magnetic local time sector in the pre-midnight region, about 0.5 hours wide, and showed movement towards higher latitudes and earlier lo- cal times. The event will be discussed in context of measurements from ground sta- tions and satellites in geosynchronous orbit. Precipitation of energetic electrons will be compared with VLF/ELF ground measurements. Features in the energetic elec- tron precipitation will be mapped to the magnetospheric equatorial plane by field line tracing.

  1. Immediate occlusal versus non-occlusal loading of single zirconia implants. A multicentre pragmatic randomised clinical trial.

    Science.gov (United States)

    Cannizzaro, Gioacchino; Torchio, Cinzia; Felice, Pietro; Leone, Michele; Esposito, Marco

    2010-01-01

    To evaluate whether immediate non-occlusal loading of single zirconia implants could reduce early failures when compared to immediate occlusal loading. Forty partially edentulous patients who received one single zirconia implant (Z-Systems) at least 10 mm long and 3.25 mm wide inserted with a torque of at least 35 Ncm were randomised to immediate occlusal or non-occlusal loading groups. All patients received provisional acrylic crowns the same day of implant placement. Provisional crowns were replaced after 4 to 5 months by definitive full ceramic crowns. Outcome measures were implant success, any complications and peri-implant marginal bone levels. One year after loading, no patients had dropped out. Five implants (12.5%) failed early: three occlusally loaded and two non-occlusally loaded. Three complications occurred, all after delivery of the definitive crowns: one crown fractured (occlusal loading), one had to be remade after debridement because of hyperplastic tissues (occlusal loading), and one crown decemented (nonocclusal loading). These differences were not statistically significant. Both groups gradually lost periimplant bone in a highly statistically significant way. One year after loading, patients subjected to non-occlusal loading lost an average of 0.7 mm of peri-implant bone versus 0.9 mm in the occlusal group. This difference in bone loss between groups was not statistically significant. There was an association between immediate post-extractive implants and implant failures (P=0.01). Four of the 10 immediate post-extractive implants (40%) failed versus one out of 30 delayed implants (3%). The results of this study do not provide a conclusive answer to whether immediate non-occlusal loading may decrease implant failures. Immediately loaded zirconia implants placed in post-extractive sites had high failure rates.

  2. First Kepler results on compact pulsators - VI. Targets in the final half of the survey phase

    DEFF Research Database (Denmark)

    H. Østensen, R.; Silvotti, R.; Charpinet, S.

    2011-01-01

    We present results from the final six months of a survey to search for pulsations in white dwarfs and hot subdwarf stars with the Kepler spacecraft. Spectroscopic observations are used to separate the objects into accurate classes, and we explore the physical parameters of the subdwarf B (sd......B) stars and white dwarfs in the sample. From the Kepler photometry and our spectroscopic data, we find that the sample contains 5 new pulsators of the V1093 Her type, one AM CVn type cataclysmic variable, and a number of other binary systems. This completes the survey for compact pulsators with Kepler....... No V361 Hya type of short-period pulsating sdB stars were found in this half, leaving us with a total of one single multiperiodic V361 Hya and 13 V1093 Her pulsators for the full survey. Except for the sdB pulsators, no other clearly pulsating hot subdwarfs or white dwarfs were found, although a few...

  3. Evaluation of single implants placed in the posterior mandibular area under immediate loading: a prospective study.

    Science.gov (United States)

    Guidetti, L G C; Monnazzi, M S; Piveta, A C G; Gabrielli, M A C; Gabrielli, M F R; Pereira Filho, V A

    2015-11-01

    The aim of this study was to evaluate the survival of single dental implants subjected to immediate function. Twelve patients with edentulous areas in the posterior mandible were included in the study. All received at least one regular platform dental implant (3.75mm×11mm or 3.75mm×13mm). Clinical and radiographic parameters were evaluated. The survival rate after 12 months was 83.3%. The implants showed no clinical mobility, had implant stability quotient values (ISQ; Osstell) around 70, bone loss of up to 2mm, and a probing depth of ≤3mm. Although the posterior mandible is an area in which the immediate loading of dental implants should be performed with caution, this treatment presented a good success rate in the present study sample. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  4. New topology of multiple-input single-output PV system for DC load applications

    Directory of Open Access Journals (Sweden)

    Mohsen M. ELhagry

    2016-12-01

    Full Text Available Improving PV system structure and maximizing the output power of a PV system has drawn many researchers attention nowadays. A proposed multi-input single-output PV system is proposed in this paper. The system consists of multiple PV modules; each module feeds a DC–DC converter. The outputs of the converters are tied together to form a DC voltage source. In order to minimize the output ripples of the converters, the control signal of each converter is time shifted from each other by a certain time interval depending on the number of converters used in the topology. In this study a battery is used as the main load, the load current used as the control variable. A fuzzy logic controller designed to modulate the operating point of the system to get the maximum power. The results show that the proposed system has very good response for various operating conditions of the PV system. In addition the output filter is minimized with excellent quality of the DC output voltage.

  5. Single Additive Enables 3D Printing of Highly Loaded Iron Oxide Suspensions.

    Science.gov (United States)

    Hodaei, Amin; Akhlaghi, Omid; Khani, Navid; Aytas, Tunahan; Sezer, Dilek; Tatli, Buse; Menceloglu, Yusuf Z; Koc, Bahattin; Akbulut, Ozge

    2018-03-21

    A single additive, a grafted copolymer, is designed to ensure the stability of suspensions of highly loaded iron oxide nanoparticles (IOPs) and to facilitate three-dimensional (3D) printing of these suspensions in the filament form. This poly (ethylene glycol)-grafted copolymer of N-[3(dimethylamino)propyl]methacrylamide and acrylic acid harnesses both electrostatic and steric repulsion to realize an optimum formulation for 3D printing. When used at 1.15 wt % (by the weight of IOPs), the suspension attains ∼81 wt % solid loading-96% of the theoretical limit as calculated by the Krieger-Dougherty equation. Rectangular, thick-walled toroidal, and thin-walled toroidal magnetic cores and a porous lattice structure are fabricated to demonstrate the utilization of this suspension as an ink for 3D printing. The electrical and magnetic properties of the magnetic cores are characterized through impedance spectroscopy (IS) and vibrating sample magnetometry (VSM), respectively. The IS indicates the possibility of utilizing wire-wound 3D printed cores as the inductive coils. The VSM verifies that the magnetic properties of IOPs before and after the ink formulation are kept almost unchanged because of the low dosage of the additive. This particle-targeted approach for the formulation of 3D printing inks allows embodiment of a fully aqueous system with utmost target material content.

  6. A FLUID PRESSURE-LOADED SINGLE CRACK LOCATED IN A ROCK MASSIF PROPAGATION TRAJECTORY CALCULATION

    Directory of Open Access Journals (Sweden)

    Cherdantsev N.V.

    2017-12-01

    Full Text Available The task solving results of a single crack filled with liquid under pressure propagation in a rock mass are presented. The rock mass is loaded with an unequal component gravitational field of stresses and represents a homogeneous elastic medium. The causes of the crack occurrence and its loading by internal pressure are not considered. In the task set, the rock mass is under conditions of a flat deformed state. In this paper, the effect of the opening on the stressed state of the rock mass and on crack propagation trajectory is not considered. The task is solved within the framework of classical concepts of the state of a crack, its stable and unstable growth in an infinite plate of brittle material, based on the theories of Griffiths - Irwin. Based on the results of the studies carried out, crack propagation trajectories are constructed for a number of the crack to the horizon inclination angle values, the characteristics associated with the strength of the enclosing rocks. An analysis is given of the critical pressures change during the crack intergrowth

  7. Objective detection of retinal vessel pulsation.

    Directory of Open Access Journals (Sweden)

    William H Morgan

    Full Text Available PURPOSE: Retinal venous pulsation detection is a subjective sign, which varies in elevated intracranial pressure, venous obstruction and glaucoma. To date no method can objectively measure and identify pulsating regions. METHOD: Using high resolution video-recordings of the optic disk and retina we measured fluctuating light absorption by haemoglobin during pulsation. Pulsation amplitude was calculated from all regions of the retinal image video-frames in a raster pattern. Segmented retinal images were formed by objectively selecting regions with amplitudes above a range of threshold values. These were compared to two observers manually drawing an outline of the pulsating areas while viewing video-clips in order to generate receiver operator characteristics. RESULTS: 216,515 image segments were analysed from 26 eyes in 18 research participants. Using data from each eye, the median area under the receiver operator curve (AU-ROC was 0.95. With all data analysed together the AU-ROC was 0.89. We defined the ideal threshold amplitude for detection of any pulsating segment being that with maximal sensitivity and specificity. This was 5 units (95% confidence interval 4.3 to 6.0 compared to 12 units before any regions were missed. A multivariate model demonstrated that ideal threshold amplitude increased with increased variation in video-sequence illumination (p = 0.0119, but between the two observers (p = 0.0919 or other variables. CONCLUSION: This technique demonstrates accurate identification of retinal vessel pulsating regions with no areas identified manually being missed with the objective technique. The amplitude values are derived objectively and may be a significant advance upon subjective ophthalmodynamometric threshold techniques.

  8. Numerical Simulations of Fluid Flow in a Single Fracture under Loading and Unloading Conditions

    Science.gov (United States)

    Kling, T.; Huo, D.; Schwarz, J. O.; Enzmann, F.; Blum, P.; Benson, S. M.

    2014-12-01

    Hydraulic aperture is one of the most important parameters to describe fluid flow in fractured rocks. Hydraulic apertures are typically determined indirectly by fluid flow experiments or hydraulic field tests based on the cubic law. Alternatively, there are different equations approximating an empirical relation between mechanical and hydraulic aperture. However, these methods most widely neglect mechanisms such as stress changes, where increasing stresses decrease the mechanical aperture and, therefore, also the effective hydraulic aperture. Hence, the objective of the present study is to simulate fluid flow in a single fracture under loading/unloading conditions and validate the results with core flooding experiments. Core flooding data and X-ray CT scans (voxel size 0.5 x 0.5 x 1 mm) of a sandstone sample with a single fracture (measured mean aperture of around 0.1 mm) were obtained by laboratory experiments. The fluid flow simulations are performed by solving the incompressible Navier-Stokes equation by using a finite volume method. Input data are given by experimental flow rates, pressures, applied stress levels and CT images of the fracture. In addition, an error analysis is performed to establish confidence in results. Results of the validation exhibit significant effects of stress on aperture distribution such as channeling and stress-dependent fracture permeability. A significant stress sensitivity of hydraulic aperture compared to the mechanical aperture was found, which can be explained by roughness changes resulting from loading. Observations indicate that with increasing stress, changes in mechanical aperture are small, while changes in hydraulic aperture can be very large. Since previous equations for hydraulic aperture do not consider changes in normal stress, a modification of these equations is proposed, including the stress-dependency of mechanical apertures to provide a better approximation to the observed hydraulic apertures.

  9. A sensitive branched DNA HIV-1 signal amplification viral load assay with single day turnaround.

    Directory of Open Access Journals (Sweden)

    Mark A Baumeister

    Full Text Available Branched DNA (bDNA is a signal amplification technology used in clinical and research laboratories to quantitatively detect nucleic acids. An overnight incubation is a significant drawback of highly sensitive bDNA assays. The VERSANT® HIV-1 RNA 3.0 Assay (bDNA ("Versant Assay" currently used in clinical laboratories was modified to allow shorter target incubation, enabling the viral load assay to be run in a single day. To dramatically reduce the target incubation from 16-18 h to 2.5 h, composition of only the "Lysis Diluent" solution was modified. Nucleic acid probes in the assay were unchanged. Performance of the modified assay (assay in development; not commercially available was evaluated and compared to the Versant Assay. Dilution series replicates (>950 results were used to demonstrate that analytical sensitivity, linearity, accuracy, and precision for the shorter modified assay are comparable to the Versant Assay. HIV RNA-positive clinical specimens (n = 135 showed no significant difference in quantification between the modified assay and the Versant Assay. Equivalent relative quantification of samples of eight genotypes was demonstrated for the two assays. Elevated levels of several potentially interfering endogenous substances had no effect on quantification or specificity of the modified assay. The modified assay with drastically improved turnaround time demonstrates the viability of signal-amplifying technology, such as bDNA, as an alternative to the PCR-based assays dominating viral load monitoring in clinical laboratories. Highly sensitive bDNA assays with a single day turnaround may be ideal for laboratories with especially stringent cost, contamination, or reliability requirements.

  10. White Dwarf Pulsational Constraints on Stellar Evolution

    Science.gov (United States)

    Dunlap, Bart H.; Clemens, J. Christopher; O'Brien, Patrick C.; Hermes, J. J.; Fuchs, Joshua T.

    2017-01-01

    The complex processes that convert a protostellar cloud into a carbon/oxygen-core white dwarf star are distilled and modeled in state of the art stellar evolution codes. Many of these processes are well-constrained, but several are uncertain or must be parameterized in the models because a complete treatment would be computationally prohibitive—turbulent motions such as convective overshoot cannot, for example, be modeled in 1D. Various free parameters in the models must therefore be calibrated. We will discuss how white dwarf pulsations can inform such calibrations. The results of all prior evolution are cemented into the interiors of white dwarf stars and, so, hidden from view. However, during certain phases of their cooling, pulsations translate the star's evolutionary history into observable surface phenomena. Because the periods of a pulsating white dwarf star depend on an internal structure assembled as it evolved to its final state, white dwarf pulsation periods can be viewed as observable endpoints of stellar evolution. For example, the thickness of the helium layer in a white dwarf directly affects its pulsations; the observed periods are, therefore, a function of the number of thermal pulses during which the star converts helium into core material on the asymptotic giant branch. Because they are also a function of several other significant evolutionary processes, several pulsation modes are necessary to tease all of these apart. Unfortunately, white dwarf pulsators typically do not display enough oscillation modes to constrain stellar evolution. To avoid this limitation, we consider the pulsations of the entire collection of hot pulsating hydrogen-atmosphere white dwarf stars (DAVs). Though any one star may not have sufficient information to place interesting constraints on its evolutionary history, taken together, the stars show a pattern of modes that allows us to test evolutionary models. For an example set of published evolutionary models, we show a

  11. A Search for Rapidly Pulsating Hot Subdwarf Stars in the GALEX Survey

    Science.gov (United States)

    Boudreaux, Thomas M.; Barlow, Brad N.; Fleming, Scott W.; Vasquez Soto, Alan; Million, Chase; Reichart, Dan E.; Haislip, Josh B.; Linder, Tyler R.; Moore, Justin P.

    2017-08-01

    NASA’s Galaxy Evolution Explorer (GALEX) provided near- and far-UV observations for approximately 77% of the sky over a 10-year period; however, the data reduction pipeline initially only released single NUV and FUV images to the community. The recently released Python module gPhoton changes this, allowing calibrated time-series aperture photometry to be extracted easily from the raw GALEX data set. Here we use gPhoton to generate light curves for all hot subdwarf B (sdB) stars that were observed by GALEX, with the intention of identifying short-period, p-mode pulsations. We find that the spacecraft’s short visit durations, uneven gaps between visits, and dither pattern make the detection of hot subdwarf pulsations difficult. Nonetheless, we detect UV variations in four previously known pulsating targets and report their UV pulsation amplitudes and frequencies. Additionally, we find that several other sdB targets not previously known to vary show promising signals in their periodograms. Using optical follow-up photometry with the Skynet Robotic Telescope Network, we confirm p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3, and report it as the most recent addition to the sdBV r class of variable stars.

  12. A Search for Rapidly Pulsating Hot Subdwarf Stars in the GALEX Survey

    Energy Technology Data Exchange (ETDEWEB)

    Boudreaux, Thomas M.; Barlow, Brad N.; Soto, Alan Vasquez [Department of Physics, High Point University, One University Parkway, High Point, NC 27268 (United States); Fleming, Scott W. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Million, Chase [Million Concepts LLC, P.O. Box 119, 141 Mary Street, Lemont, PA 16851 (United States); Reichart, Dan E.; Haislip, Josh B.; Moore, Justin P. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States); Linder, Tyler R. [Department of Physics, Eastern Illinois University, 600 Lincoln Avenue, Charleston, IL 61920 (United States)

    2017-08-20

    NASA’s Galaxy Evolution Explorer ( GALEX ) provided near- and far-UV observations for approximately 77% of the sky over a 10-year period; however, the data reduction pipeline initially only released single NUV and FUV images to the community. The recently released Python module gPhoton changes this, allowing calibrated time-series aperture photometry to be extracted easily from the raw GALEX data set. Here we use gPhoton to generate light curves for all hot subdwarf B (sdB) stars that were observed by GALEX , with the intention of identifying short-period, p-mode pulsations. We find that the spacecraft’s short visit durations, uneven gaps between visits, and dither pattern make the detection of hot subdwarf pulsations difficult. Nonetheless, we detect UV variations in four previously known pulsating targets and report their UV pulsation amplitudes and frequencies. Additionally, we find that several other sdB targets not previously known to vary show promising signals in their periodograms. Using optical follow-up photometry with the Skynet Robotic Telescope Network, we confirm p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3, and report it as the most recent addition to the sdBV{sub r} class of variable stars.

  13. A Search for Rapidly Pulsating Hot Subdwarf Stars in the GALEX Survey

    International Nuclear Information System (INIS)

    Boudreaux, Thomas M.; Barlow, Brad N.; Soto, Alan Vasquez; Fleming, Scott W.; Million, Chase; Reichart, Dan E.; Haislip, Josh B.; Moore, Justin P.; Linder, Tyler R.

    2017-01-01

    NASA’s Galaxy Evolution Explorer ( GALEX ) provided near- and far-UV observations for approximately 77% of the sky over a 10-year period; however, the data reduction pipeline initially only released single NUV and FUV images to the community. The recently released Python module gPhoton changes this, allowing calibrated time-series aperture photometry to be extracted easily from the raw GALEX data set. Here we use gPhoton to generate light curves for all hot subdwarf B (sdB) stars that were observed by GALEX , with the intention of identifying short-period, p-mode pulsations. We find that the spacecraft’s short visit durations, uneven gaps between visits, and dither pattern make the detection of hot subdwarf pulsations difficult. Nonetheless, we detect UV variations in four previously known pulsating targets and report their UV pulsation amplitudes and frequencies. Additionally, we find that several other sdB targets not previously known to vary show promising signals in their periodograms. Using optical follow-up photometry with the Skynet Robotic Telescope Network, we confirm p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3, and report it as the most recent addition to the sdBV r class of variable stars.

  14. Modeling of pulsating heat pipes.

    Energy Technology Data Exchange (ETDEWEB)

    Givler, Richard C.; Martinez, Mario J.

    2009-08-01

    This report summarizes the results of a computer model that describes the behavior of pulsating heat pipes (PHP). The purpose of the project was to develop a highly efficient (as compared to the heat transfer capability of solid copper) thermal groundplane (TGP) using silicon carbide (SiC) as the substrate material and water as the working fluid. The objective of this project is to develop a multi-physics model for this complex phenomenon to assist with an understanding of how PHPs operate and to be able to understand how various parameters (geometry, fill ratio, materials, working fluid, etc.) affect its performance. The physical processes describing a PHP are highly coupled. Understanding its operation is further complicated by the non-equilibrium nature of the interplay between evaporation/condensation, bubble growth and collapse or coalescence, and the coupled response of the multiphase fluid dynamics among the different channels. A comprehensive theory of operation and design tools for PHPs is still an unrealized task. In the following we first analyze, in some detail, a simple model that has been proposed to describe PHP behavior. Although it includes fundamental features of a PHP, it also makes some assumptions to keep the model tractable. In an effort to improve on current modeling practice, we constructed a model for a PHP using some unique features available in FLOW-3D, version 9.2-3 (Flow Science, 2007). We believe that this flow modeling software retains more of the salient features of a PHP and thus, provides a closer representation of its behavior.

  15. Clinical Outcomes After Immediate and Late Implant Loading for a Single Missing Tooth in the Anterior Maxilla.

    Science.gov (United States)

    Yildiz, Pnar; Zortuk, Mustafa; Kiliç, Erdem; Dinçel, Mehmet; Albayrak, Haydar

    2016-08-01

    This study compared the clinical outcomes of 1-year follow-up of immediate and late implant loading after implant restoration of a single tooth in the anterior maxilla. Thirty-three patients with missing teeth in the anterior maxilla were included in this study (18 immediate loading and 15 late loading). Standard periapical radiographs were obtained to evaluate the vertical bone loss around the implant. For both implant groups, periimplant parameters (probing depth, gingival bleeding index, gingival index (GI), modified plaque index, width of keratinized gingiva) were evaluated. There were no significant differences in bone loss, the widths of keratinized gingiva, the GI, and modified plaque index between the immediate implant loading and late implant loading groups (P > 0.05). A significant difference in the probing depth was observed between these groups at the initial and 1-month evaluations (P replacement of a missing tooth in anterior maxilla.

  16. Simulation of laminar pulsations in a rectangular duct containing a rod

    Energy Technology Data Exchange (ETDEWEB)

    Chettle, A.; Lightstone, M.; Tullis, S. [McMaster Univ., Dept. of Mechanical Engineering, Ontario (Canada)

    2011-07-01

    Flow pulsations in subchannel geometries are important in the homogenization of fluid temperatures within a fuel rod bundle cross-section. Recent experimental work by Gosset and Tavoularis has indicated that flow pulsations can occur under laminar conditions. This paper presents the results of computational fluid dynamics investigation of laminar flow pulsations in a single rod geometry matching the experimental geometry and conditions of Gosset and Tavoularis. A gap height to rod diameter ratio of 0.3 and Reynolds numbers of 718 and 900 were considered. Rough agreement between the simulations and the experimental results was obtained for the measured frequency, and the simulations revealed highly complex flow patterns throughout the duct cross-section. (author)

  17. Early Loading of Single-Piece Implant for Partially Edentulous Posterior Arch: A Prospective One-Year Case Report

    Directory of Open Access Journals (Sweden)

    Amol Beldar

    2013-01-01

    Full Text Available Implant therapy is now well established, and there is an increasing need for shorter rehabilitation time. Original prerequisites of osseointegration have been reassessed to satisfy continuously increasing patient's expectation of reduced treatment time, improved esthetics, and increased comfort. Shorter healing time may be appropriate in some circumstances, and examples of early loading have been reported in animal and human studies. However, to date there are insufficient data to determine a universally acceptable opinion on early loading of implants for single-tooth replacement. This case report involves early loading, combined with construction of a restoration, inserted directly after 6 weeks of implant surgery and followup of one year.

  18. Early Loading of Single-Piece Implant for Partially Edentulous Posterior Arch: A Prospective One-Year Case Report

    Science.gov (United States)

    Beldar, Amol; Bhongade, Manohar L.; Byakod, Girish; Buregoni, Chandrashekar

    2013-01-01

    Implant therapy is now well established, and there is an increasing need for shorter rehabilitation time. Original prerequisites of osseointegration have been reassessed to satisfy continuously increasing patient's expectation of reduced treatment time, improved esthetics, and increased comfort. Shorter healing time may be appropriate in some circumstances, and examples of early loading have been reported in animal and human studies. However, to date there are insufficient data to determine a universally acceptable opinion on early loading of implants for single-tooth replacement. This case report involves early loading, combined with construction of a restoration, inserted directly after 6 weeks of implant surgery and followup of one year. PMID:23710375

  19. Pulsating star research and the Gaia revolution

    Directory of Open Access Journals (Sweden)

    Eyer Laurent

    2017-01-01

    Full Text Available In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.

  20. Pulsating Heat Pipes, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Large radiator panels, based upon state of the art conventional heat pipes with attached fins for thermal load distribution and dissipation is the current baseline...

  1. Numerical assessment of pulsating water jet in the conical diffusers

    Science.gov (United States)

    Tanasa, Constantin; Ciocan, Tiberiu; Muntean, Sebastian

    2017-11-01

    The hydraulic fluctuations associated with partial load operating conditions of Francis turbines are often periodic and characterized by the presence of a vortex rope. Two types of pressure fluctuations associated with the draft tube surge are identified in the literature. The first is an asynchronous (rotating) pressure fluctuation due to the precession of the helical vortex around the axis of the draft tube. The second type of fluctuation is a synchronous (plunging) fluctuation. The plunging fluctuations correspond to the flow field oscillations in the whole hydraulic passage, and are generally propagated overall in the hydraulic system. The paper introduced a new control method, which consists in injecting a pulsating axial water jet along to the draft tube axis. Nevertheless, the great calling of this control method is to mitigate the vortex rope effects targeting the vortex sheet and corresponding plunging component. In this paper, is presented our 3D numerical investigations with and without pulsating axial water jet control method in order to evaluate the concept.

  2. Pulsation properties of Mira long period variables

    International Nuclear Information System (INIS)

    Cahn, J.H.

    1980-01-01

    A matter of great interest to variable star students concerns the mode of pulsation of Mira long period variables. In this report we first give observational evidence for the pulsation constant Q. We then compare the observations with calculations. Next, we review two interesting groups of papers dealing with hydrodynamic properties of long period variables. In the first, a fully dynamic nonlinear calculation maps out the Mira instability domain. In the second, special attention is paid to shock propagation beyond the photosphere which in large measure accounts for the complex spectra from this region. (orig./WL)

  3. Gas compressor with side branch absorber for pulsation control

    Science.gov (United States)

    Harris, Ralph E [San Antonio, TX; Scrivner, Christine M [San Antonio, TX; Broerman, III, Eugene L.

    2011-05-24

    A method and system for reducing pulsation in lateral piping associated with a gas compressor system. A tunable side branch absorber (TSBA) is installed on the lateral piping. A pulsation sensor is placed in the lateral piping, to measure pulsation within the piping. The sensor output signals are delivered to a controller, which controls actuators that change the acoustic dimensions of the SBA.

  4. Immediate Nonfunctional Loading of Two Single-Maxillary Postextractive Implants: 6-Year Postloading Results of Two Case Reports

    OpenAIRE

    Ariano, Vincenzo; Mancini, Manuele; Cardi, Andrea; Cond?, Roberta; Cerroni, Loredana; Pasquantonio, Guido

    2016-01-01

    Objectives. The aim of the study was to evaluate and compare crestal bone loss of single-maxillary immediate postextractive implants and immediate nonfunctional loading (INFL) during 72 months of follow-up. Material and Methods. Two single titanium implants (Certain Prevail, Biomet 3I, USA) were placed in two patients using INFL technique. Implant stability and crestal bone level were measured on periapical radiographs at 1, 3, and 6 months after surgery. Results. All osseointegrated implants...

  5. Immediate Loading of Single Implants in the Anterior Maxilla: A 1-Year Prospective Clinical Study on 34 Patients

    Science.gov (United States)

    Stanley, Miguel; Jordao, Beatriz Mota

    2017-01-01

    Purpose To present the outcomes of immediately loaded single implants placed in the anterior maxilla. Methods Over a 2-year period, all patients referred to a private clinic were considered for enrolment in this study. Inclusion criteria were single-tooth placement in postextraction sockets or healed sites of the anterior maxilla. All implants were immediately loaded and followed for a period of 1 year after the placement of definitive crowns. The outcome measures were implant stability, survival, and success. Results 34 patients were selected and 43 tapered implants with a knife-edge thread design and a nanostructured, calcium-incorporated surface (Anyridge®, Megagen, Gyeongsang, Korea) were installed. Two implants were not sufficiently stable at placement (ISQ immediate loading; 41 implants had an ISQ ≥ 60 at placement and were immediately loaded. One year after the placement of definitive crowns, no implant failures were reported, for a survival rate of 100%. No biological complications were found, but 2 implants had their prosthetic abutments loosened: the implant success rate was 95.2%. Conclusions In the present study on the immediate loading of single implants in the anterior maxilla, positive outcomes were reported, with high survival (100%) and success (95.2%) rates (the present study has been registered in the ISRCTN registry, a publicly available trial register recognized by WHO and ICMJE, with number ISRCTN12935478). PMID:28611844

  6. Immediate Loading of Single Implants in the Anterior Maxilla: A 1-Year Prospective Clinical Study on 34 Patients

    Directory of Open Access Journals (Sweden)

    Miguel Stanley

    2017-01-01

    Full Text Available Purpose. To present the outcomes of immediately loaded single implants placed in the anterior maxilla. Methods. Over a 2-year period, all patients referred to a private clinic were considered for enrolment in this study. Inclusion criteria were single-tooth placement in postextraction sockets or healed sites of the anterior maxilla. All implants were immediately loaded and followed for a period of 1 year after the placement of definitive crowns. The outcome measures were implant stability, survival, and success. Results. 34 patients were selected and 43 tapered implants with a knife-edge thread design and a nanostructured, calcium-incorporated surface (Anyridge®, Megagen, Gyeongsang, Korea were installed. Two implants were not sufficiently stable at placement (ISQ < 60 and were considered failed for immediate loading; 41 implants had an ISQ ≥ 60 at placement and were immediately loaded. One year after the placement of definitive crowns, no implant failures were reported, for a survival rate of 100%. No biological complications were found, but 2 implants had their prosthetic abutments loosened: the implant success rate was 95.2%. Conclusions. In the present study on the immediate loading of single implants in the anterior maxilla, positive outcomes were reported, with high survival (100% and success (95.2% rates (the present study has been registered in the ISRCTN registry, a publicly available trial register recognized by WHO and ICMJE, with number ISRCTN12935478.

  7. Immediate Loading of Single Implants in the Anterior Maxilla: A 1-Year Prospective Clinical Study on 34 Patients.

    Science.gov (United States)

    Stanley, Miguel; Braga, Filipa Calheiros; Jordao, Beatriz Mota

    2017-01-01

    To present the outcomes of immediately loaded single implants placed in the anterior maxilla. Over a 2-year period, all patients referred to a private clinic were considered for enrolment in this study. Inclusion criteria were single-tooth placement in postextraction sockets or healed sites of the anterior maxilla. All implants were immediately loaded and followed for a period of 1 year after the placement of definitive crowns. The outcome measures were implant stability, survival, and success. 34 patients were selected and 43 tapered implants with a knife-edge thread design and a nanostructured, calcium-incorporated surface (Anyridge®, Megagen, Gyeongsang, Korea) were installed. Two implants were not sufficiently stable at placement (ISQ immediate loading; 41 implants had an ISQ ≥ 60 at placement and were immediately loaded. One year after the placement of definitive crowns, no implant failures were reported, for a survival rate of 100%. No biological complications were found, but 2 implants had their prosthetic abutments loosened: the implant success rate was 95.2%. In the present study on the immediate loading of single implants in the anterior maxilla, positive outcomes were reported, with high survival (100%) and success (95.2%) rates (the present study has been registered in the ISRCTN registry, a publicly available trial register recognized by WHO and ICMJE, with number ISRCTN12935478).

  8. A Radiographic Comparison of Progressive and Conventional Loading on Crestal Bone Loss and Density in Single Implants

    Directory of Open Access Journals (Sweden)

    Majid Sorouri

    2013-01-01

    Full Text Available Objectives: Crestal bone loss is a biologic complication in implant dentistry. The aim of this study was to compare the effect of progressive and conventional loading on crestal bone height and bone density around single osseointegrated implants in posterior maxilla by a longitudinal radiographic assessment technique.Materials and methods: Twenty micro thread implants were placed in 10 patients (two implants per patient. One of the two implants of each patient was assigned to progressive and the other to conventional loading groups. Eight weeks after surgery, conventional implants were restored with a metal ceramic crown and progressive group underwent a progressive loading protocol. The progressive loading group takes different temporary acrylic crowns at 2, 4 and 6 months. After eight months, acrylic crowns were replaced with metal ceramic crown. Computer radiography of both progressive and conventional implants was taken at 2, 4, 6, and 12 months. Image analysis was performed to measure height of crestal bone loss and bone density.Results: The mean values of crestal bone loss at month 12 were 0.11 (0.19 mm for progressively and 0.36 (0.36 mm for conventionally loaded implants, with a statistically significant difference (P 0.05.Conclusion: Progressive group showed less crestal bone loss in single osseointegrated implant than conventional group. Bone density around progressively loaded implants showed increase in crestal, middle and apica

  9. First Kepler results on compact pulsators - I. Survey target selection and the first pulsators

    DEFF Research Database (Denmark)

    Østensen, Roy H.; Silvotti, Roberto; Charpinet, S.

    2010-01-01

    We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic observations are presented to separate the objects into ...... that hybrid behaviour may be common in these stars, also outside the boundary temperature region where hybrid pulsators have hitherto been found....

  10. Characterization of voids in shock-loaded Al single crystal by combining X-ray tomography and electron microscopy

    DEFF Research Database (Denmark)

    Hong, Chuanshi; Fæster, Søren; Hansen, Niels

    2017-01-01

    A combination of X-ray tomography and electron backscatter diffraction (EBSD) was applied to investigate both the shape of voids and the plastic deformation around voids in an Al single crystal shock-loaded in the direction. The combination of these two techniques allows the addition of crystallo...

  11. The First Kepler Observations of the Pulsations of R Coronae Borealis Stars

    Science.gov (United States)

    Clayton, Geoffrey C.; Jeffery, C. Simon; Montiel, Edward; Saio, Hideyuki; Ramsay, Gavin

    2017-01-01

    K2 has opened a new avenue for the detailed study of the pulsations of the R Coronae Borealis (RCB) stars. These observations are key to understanding the evolution of the RCB stars because their masses cannot be accurately estimated by other means. The ~75 days of near continuous, high-precision observations are ideal for our planned analysis of the brightness variations of the RCB stars. We are observing about 15 RCB stars In K2 Fields 7, 9, and 11.These observations will provide a better understanding of the pulsation mechanisms and modes in RCB stars. RCB stars are thought to be ~0.8-0.9 M(Sun) from previous stellar pulsation modeling. These estimated masses agree well with the predicted masses of the merger products of a CO- and a He-WD. Final-flash stars, since they are single white dwarfs, should typically have masses of 0.55-0.6 M(Sun). No cool RCB star, with T(eff) = 5000-7000 K, is known to be a binary so these mass estimates are of great importance to understanding the evolution of these enigmatic stars. RCB stars show periodic or semi-periodic light and radial velocity fluctuations due to both radial and non-radial pulsations. These stars show pulsation periods in the 40-100 d range. These variations are separate from the large declines in brightness caused by dust forming around the star. The pulsations in RCB stars are thought to arise through strange-mode instabilities. Strange modes occur in stars with high luminosity where radiation pressure dominates. RCB stars comprise a peculiar and rare class of stars that offers an excellent opportunity to reveal crucial insights into the advanced stages of stellar evolution.

  12. Immediate and delayed loading of fixed dental prostheses supported by single or two splinted implants: A histomorphometric study in dogs.

    Science.gov (United States)

    Cesaretti, G; Lang, N P; Viganò, P; Bengazi, F; Apaza Alccayhuaman, K A; Botticelli, D

    2018-04-01

    To evaluate presumptive differences in osseointegration at implants supporting crowns that are physiologically loaded either immediately or 3 months after installation. All premolars and first molars were extracted bilaterally in six dogs. After 3 months of healing, three implants were installed on the premolar region and two in the molar region in one side of the mandible. Likewise, after another 3 months, five implants were installed in the contralateral side, and impressions were taken bilaterally. Within 48 hours, two single crowns were screwed bilaterally onto two implants in the premolar region, and two splinted crowns reproducing the shape of the first molar were screwed bilaterally onto the implants in the molar region. The mesial implants were used as no-loaded controls. Sacrifices were performed after 3 months, and histological analyses were performed. At the premolar sites, mineralised bone-to-implant contact (MBIC%) was 78.0 ± 4.0% and 70.9 ± 7.9% at the delayed and immediately loaded sites, respectively. This difference was statistically significant. At the control implants, MBIC% was 61.4 ± 14.7% and 63.1 ± 13.1% at the delayed and the immediately loaded sites, respectively. At the molar sites, MBIC% was 79.2 ± 10.9% and 61.1 ± 10.3% at the delayed and immediately loaded sites, respectively. Applying a delayed loading to fixed dental prostheses supported by single or two splinted implants yielded higher proportions of bone-to-implant contact (osseointegration) compared to immediately loaded implants. Moreover, both types of loading protocols yielded a higher rate of osseointegration compared to unloaded implant sites after 3 months following implant installation. © 2018 John Wiley & Sons Ltd.

  13. Test Characteristics of Neck Fullness and Witnessed Neck Pulsations in the Diagnosis of Typical AV Nodal Reentrant Tachycardia

    Science.gov (United States)

    Sakhuja, Rahul; Smith, Lisa M; Tseng, Zian H; Badhwar, Nitish; Lee, Byron K; Lee, Randall J; Scheinman, Melvin M; Olgin, Jeffrey E; Marcus, Gregory M

    2011-01-01

    Summary Background Claims in the medical literature suggest that neck fullness and witnessed neck pulsations are useful in the diagnosis of typical AV nodal reentrant tachycardia (AVNRT). Hypothesis Neck fullness and witnessed neck pulsations have a high positive predictive value in the diagnosis of typical AVNRT. Methods We performed a cross sectional study of consecutive patients with palpitations presenting to a single electrophysiology (EP) laboratory over a 1 year period. Each patient underwent a standard questionnaire regarding neck fullness and/or witnessed neck pulsations during their palpitations. The reference standard for diagnosis was determined by electrocardiogram and invasive EP studies. Results Comparing typical AVNRT to atrial fibrillation (AF) or atrial flutter (AFL) patients, the proportions with neck fullness and witnessed neck pulsations did not significantly differ: in the best case scenario (using the upper end of the 95% confidence interval [CI]), none of the positive or negative predictive values exceeded 79%. After restricting the population to those with supraventricular tachycardia other than AF or AFL (SVT), neck fullness again exhibited poor test characteristics; however, witnessed neck pulsations exhibited a specificity of 97% (95% CI 90–100%) and a positive predictive value of 83% (95% CI 52–98%). After adjustment for potential confounders, SVT patients with witnessed neck pulsations had a 7 fold greater odds of having typical AVNRT, p=0.029. Conclusions Although neither neck fullness nor witnessed neck pulsations are useful in distinguishing typical AVNRT from AF or AFL, witnessed neck pulsations are specific for the presence of typical AVNRT among those with SVT. PMID:19479968

  14. LAMOST views δ Scuti pulsating stars

    Science.gov (United States)

    Qian, S.-B.; Li, L.-J.; He, J.-J.; Zhang, J.; Zhu, L.-Y.; Han, Z.-T.

    2018-03-01

    About 766 δ Scuti stars were observed by LAMOST by 2017 June 16. Stellar atmospheric parameters of 525 variables were determined, while spectral types were obtained for all samples. In the paper, those spectroscopic data are catalogued. We detect a group of 131 unusual and cool variable stars (UCVs) that are distinguished from the normal δ Scuti stars (NDSTs). On the H-R diagram and the log g-T diagram, the UCVs are far beyond the red edge of pulsational instability trip. Their effective temperatures are lower than 6700 K with periods in the range from 0.09 to 0.22 d. NDSTs have metallicity close to that of the Sun as expected, while UCVs are slightly metal poor than NDSTs. The two peaks on the distributions of the period and stellar atmospheric parameters are all caused by the existence of UCVs. When those UCVs are excluded, it is discovered that the effective temperature, the gravitational acceleration, and the metallicity all are correlated with the pulsating period for NDSTs and their physical properties and evolutionary states are discussed. Detection of those UCVs indicates that about 25 per cent of the known δ Scuti stars may be misclassified. However, if some of them are confirmed to be pulsating stars, they will be a new-type pulsator and their investigations will shed light on theoretical instability domains and on the theories of interacting between the pulsation and the convection of solar-type stars. Meanwhile, 88 δ Scuti stars are detected to be the candidates of binary or multiple systems.

  15. A Pulsation Mechanism for GW Virginis Variables

    Science.gov (United States)

    Cox, Arthur N.

    2003-03-01

    The mechanism that produces pulsations in the hottest pre-white dwarfs has been uncertain since the early work indicated that helium is a poison that smooths opacity bumps in the opacity-temperature plane caused by the ionizations of the large observed amounts of carbon and oxygen. Very little helium seemed to be needed to prevent the kappa effect pulsation driving, but helium amounts of almost half of the mass in the surface composition are observed in the pulsating PG 1159-035 stars called the GW Virginis variables. Rather little change in the C and O surface abundances is observed from the hottest (RX J2117.1+3412 at 170,000 K) to the coolest (PG 0122+200 at 80,000 K) GW Vir variables. Actually the shortest observed periods (300-400 s) of these variables are generally predicted to be unstable in all models, but the longest observed periods (up to 1000 s) are difficult to excite. Three recent investigations differ in their conclusions, with two finding that helium and even a slight amount of hydrogen does not prevent the kappa effect of C and O ionizations. A more detailed study reported here confirms the poisoning effect of helium. However, the ionization K- and L-edge opacity of the original iron, whose global abundance is unaffected by all previous evolution, especially if enhanced by radiation absorption levitation, can give different, previously unexplored, opacity driving that can explain the observed pulsations. But even this iron ionization driving can be somewhat poisoned by bump smoothing if the C and O abundances are large. Nonvariable GW Vir stars in the observed instability strip could be the result of small composition variations in the pulsation driving layers.

  16. Immediate loading of post-extractive versus delayed placed single implants in the anterior maxilla: outcome of a pragmatic multicenter randomised controlled trial 1-year after loading.

    Science.gov (United States)

    Esposito, Marco; Barausse, Carlo; Pistilli, Roberto; Jacotti, Michele; Grandi, Giovanni; Tuco, Lorenzo; Felice, Pietro

    2015-01-01

    To compare the effectiveness of immediate post-extractive single implants with delayed implants, placed in preserved sockets after 4 months of healing. Implants that achieved an insertion torque of at least 35 Ncm were immediately non-occlusally loaded. Just after tooth extraction, and in the presence of less than 4 mm of vertical loss of the buccal bone in relation to the palatal wall, 106 patients requiring a single immediate post-extractive implant in the maxilla from second to second premolar were randomly allocated to immediate implant placement (immediate group; 54 patients) or to socket preservation using anorganic bovine bone covered by a resorbable collagen barrier (delayed group; 52 patients), according to a parallel group design at three different centres. Bone-to-implant gaps were to be filled with anorganic bovine bone, however this was not carried out in 17 patients (corresponding to 40% of those who should have been grafted). Four months after socket preservation, delayed implants were placed. Implants inserted with an insertion torque of at least 35 Ncm were immediately loaded with non-occluding provisional single crowns, then replaced after 4 months by definitive crowns. Patients were followed up to 1 year after loading. Outcome measures were implant failures, complications, aesthetics assessed using the pink esthetic score (PES), peri-implant marginal bone level changes and patient satisfaction recorded by blinded assessors. Nineteen (35%) implants were not immediately loaded in the immediate group versus 39 (75%) implants in the delayed placement group because an insertion torque superior to 35 Ncm could not be obtained. Six patients dropped out 4 months after loading from the delayed group versus none in the immediate group. Two implants failed in the immediate group (6%) versus none in the delayed group, with the difference showing no statistical significance (difference in proportions = 0.04; 95% CI: -0.03 to 0.11; P = 0.187). Eight minor

  17. Experimental study of Large-scale cryogenic Pulsating Heat Pipe

    Science.gov (United States)

    Barba, Maria; Bruce, Romain; Bonelli, Antoine; Baudouy, Bertrand

    2017-12-01

    Pulsating Heat Pipes (PHP) are passive two-phase heat transfer devices consisting of a long capillary tube bent into many U-turns connecting the condenser part to the evaporator part. They are thermally driven by an oscillatory flow of liquid slugs and vapor plugs coming from phase changes and pressure differences along the tube. The coupling of hydrodynamic and thermodynamic effects allows high heat transfer performances. Three closed-loop pulsating heat pipes have been developed by the DACM (Department of Accelerators, Cryogenics and Magnetism) of CEA Paris-Saclay, France. Each PHP measures 3.7 meters long (0.35 m for the condenser and the evaporator and 3 m for the adiabatic part), being almost 20 times longer than the longest cryogenic PHP tested. These PHPs have 36, 22 and 12 parallel channels. Numerous tests have been performed in horizontal position (the closest configuration to non-gravity) using nitrogen as working fluid, operating between 75 and 90 K. The inner and outer diameters of the stainless steel capillary tubes are 1.5 and 2 mm respectively. The PHPs were operated at different filling ratios (20 to 90 %), heat input powers (3 to 20 W) and evaporator and condenser temperatures (75 to 90 K). As a result, the PHP with 36 parallel channels achieves a certain level of stability during more than thirty minutes with an effective thermal conductivity up to 200 kW/m.K at 10 W heat load and during forty minutes with an effective thermal conductivity close to 300 kW/m.K at 5 W heat load.

  18. Immediate Nonfunctional Loading of Two Single-Maxillary Postextractive Implants: 6-Year Postloading Results of Two Case Reports

    Directory of Open Access Journals (Sweden)

    Vincenzo Ariano

    2016-01-01

    Full Text Available Objectives. The aim of the study was to evaluate and compare crestal bone loss of single-maxillary immediate postextractive implants and immediate nonfunctional loading (INFL during 72 months of follow-up. Material and Methods. Two single titanium implants (Certain Prevail, Biomet 3I, USA were placed in two patients using INFL technique. Implant stability and crestal bone level were measured on periapical radiographs at 1, 3, and 6 months after surgery. Results. All osseointegrated implants were clinically successful after 6 years of functional loading. Conclusion. Within the limit of the present case report, the paper supports the concept that INFL of single dental implant can be a successful treatment procedure.

  19. Load bearing capacity, fracture mode, and wear performance of digitally veneered full-ceramic single crowns.

    Science.gov (United States)

    Schubert, Oliver; Nold, Ephraim; Obermeier, Matthias; Erdelt, Kurt; Stimmelmayr, Michael; Beuer, Florian

    Computer-aided technologies can help to minimize clinical complications of zirconia-based restorations such as veneering porcelain fractures. The aim of this study was to evaluate different veneering approaches for zirconia single crowns regarding contact wear, fracture strength, and failure mode. Six different types of computer-aided design (CAD) crowns were manufactured and conventionally cemented on 10 metal dies each: three groups with a zirconia framework and a CAD/CAM-fabricated veneering cap ("digital veneering system": DVS, CAD-on, Infix CAD), zirconia-based crowns with pressed veneering caps (Infix Press), zirconia framework containing the dentin layer with only the incisal enamel material added (dentin-core), and conventional substructure with powder buildup veneering porcelain (layering technique). All specimens were submitted to artificial aging (120,000 mechanical cycles, 50 N load, 0.7-mm sliding movement, 320 thermocycles). After contact wear was measured with a laser scanning system, fracture resistance and failure mode were examined using a universal testing machine and a scanning electron microscope. Statistical analysis was performed at a significance level of 5%. No statistical difference was revealed regarding the contact wear of the restorations (P = 0.171; ANOVA). No significant difference was found regarding the fracture resistance of the crowns (P = 0.112; ANOVA). Failure analysis revealed three different failure patterns: cohesive veneering fracture, adhesive delamination, and total fracture, with a characteristic distribution between the groups. All tested specimens survived artificial aging and exhibited clinically acceptable wear resistance and fracture resistance. Digital veneering techniques offer a promising, time- and cost-effective manufacturing process for all-ceramic restorations and may usefully complement the digital workflow.

  20. Stability of an anaerobic single reactor filled with dolomitic limestone with increased organic load of sugarcane

    Directory of Open Access Journals (Sweden)

    Maria Magdalena Ribas Döll

    2017-12-01

    Full Text Available The anaerobic single-stage reactor was evaluated to treat vinasse and to evaluate its stability. This bench reactor was filled with dolomitic limestone with a horizontal plug flow to simulate a drainage channel. The experiment lasted 129 days while the reactor was submitted to different applied organic concentrations (chronologically applied: 3.0; 5.0; 12.0; 9.0 and 7.5 g L-1 as COD, chemical oxygen demand. COD removals were 50% and 9% with 3.0 and 7.5 g L-1, respectively. With 12.0 g L-1, reactor efficiency increased to 33%, with an abrupt drop to 3% on the 84th day. Therefore, in order to avoid reactor collapse, a remedial measure was necessary. The system remained in batch without feeding for 19 days (from the 85th to the 104th day with 9.0 g L-1. Afterwards, it was observed that the performance of the system tended to stabilize, reaching 47% with 7.5 g L-1 in the 118th day. At the end of the experiment, the potassium content of the wastewater decreased from 800 mg L-1 to 594 mg L-1 (on an average 25% and calcium and magnesium increased within the reactor liquor. The dissolution of the limestone inside the liquor reactor probably caused this result. After the treatment with limestone, the average pH value of the effluent increased from 4.9 to over 6.0 in all organic concentrations. It could be concluded that the reactor filled with dolomitic limestone in these operational conditions assured a low efficiency in COD removal, potassium reduction, increasing values of pH, alkalinity, calcium and magnesium. The instability was observed when there was increase in organic load to 12 g L-1 with subsequent recovery.

  1. Immediate versus early loading of 6.5 mm-long flapless-placed single implants: a 4-year after loading report of a split-mouth randomised controlled trial.

    Science.gov (United States)

    Cannizzaro, Gioacchino; Felice, Pietro; Leone, Michele; Ferri, Vittorio; Viola, Paolo; Esposito, Marco

    2012-01-01

    To evaluate the medium-term effectiveness of 6.5 mm-long flapless-placed single implants immediately or early loaded at 6 weeks. Thirty patients received two single NanoTite external hex Biomet 3i implants each, which were then randomly allocated to be immediately or early loaded according to a splitmouth design. Implants had to be inserted with a minimum torque of >40 Ncm. Provisional crowns were put in slight occlusal contact and replaced by definitive crowns 3 months after loading. Patients were followed for 4 years after loading. Outcome measures were implant failures, biological and biomechanical complications, peri-implant marginal bone level changes, and patient preference. Twenty-nine implants were immediately loaded and 31 early loaded. Four years after loading, no drop-outs occurred. One implant failed in each group within 2 months after loading. Seven patients experienced complications at immediately loaded implants and 6 at early loaded implants. There were no statistically significant differences between groups for implant losses, complications, mean marginal bone level changes and patient preference. Flapless-placed 6.5 mm-long single implants can be immediately loaded and remain successful up to 4 years after loading. Even longer follow-ups are still needed to evaluate the longterm prognosis of short implants.

  2. Evaluation of pump pulsation in respirable size-selective sampling: part II. Changes in sampling efficiency.

    Science.gov (United States)

    Lee, Eun Gyung; Lee, Taekhee; Kim, Seung Won; Lee, Larry; Flemmer, Michael M; Harper, Martin

    2014-01-01

    This second, and concluding, part of this study evaluated changes in sampling efficiency of respirable size-selective samplers due to air pulsations generated by the selected personal sampling pumps characterized in Part I (Lee E, Lee L, Möhlmann C et al. Evaluation of pump pulsation in respirable size-selective sampling: Part I. Pulsation measurements. Ann Occup Hyg 2013). Nine particle sizes of monodisperse ammonium fluorescein (from 1 to 9 μm mass median aerodynamic diameter) were generated individually by a vibrating orifice aerosol generator from dilute solutions of fluorescein in aqueous ammonia and then injected into an environmental chamber. To collect these particles, 10-mm nylon cyclones, also known as Dorr-Oliver (DO) cyclones, were used with five medium volumetric flow rate pumps. Those were the Apex IS, HFS513, GilAir5, Elite5, and Basic5 pumps, which were found in Part I to generate pulsations of 5% (the lowest), 25%, 30%, 56%, and 70% (the highest), respectively. GK2.69 cyclones were used with the Legacy [pump pulsation (PP) = 15%] and Elite12 (PP = 41%) pumps for collection at high flows. The DO cyclone was also used to evaluate changes in sampling efficiency due to pulse shape. The HFS513 pump, which generates a more complex pulse shape, was compared to a single sine wave fluctuation generated by a piston. The luminescent intensity of the fluorescein extracted from each sample was measured with a luminescence spectrometer. Sampling efficiencies were obtained by dividing the intensity of the fluorescein extracted from the filter placed in a cyclone with the intensity obtained from the filter used with a sharp-edged reference sampler. Then, sampling efficiency curves were generated using a sigmoid function with three parameters and each sampling efficiency curve was compared to that of the reference cyclone by constructing bias maps. In general, no change in sampling efficiency (bias under ±10%) was observed until pulsations exceeded 25% for the

  3. Physical scale modeling of single free head piles under lateral loading in cohesive soils

    Directory of Open Access Journals (Sweden)

    Edgar Leonardo Salamanca-Medina

    2017-06-01

    Full Text Available This paper presents the results of the small scale modeling of free head wood piles under horizontal loading in cohesive soils, tested in order to compare the results with analytical models proposed by various authors. Characteristic Load (CLM and P-Y Curves methods were used for the prediction of lateral deflections at the head of the piles and the method proposed by Broms for estimating the ultimate lateral load. These predictions were compared with the results of the physical modeling, obtaining a good approximation between them.

  4. Three-Dimensional, Inelastic Response of Single-Edge Notch Bend Specimens Subjected to Impact Loading

    Science.gov (United States)

    1993-08-01

    fracture by a swinging pendulum . The loading duration of the Charpy test is on the order of 200.u-seconds [78,9]. The difference between the energy...levels of the pendulum before and after impact with the specimen provides the total energy absorbed by the specimen. By using a pre-cracked Charpy specimen...faster loading rates adopted by Nakamura approximate loading durations observed in Charpy V-Notch (CVN) test speci- mens [78,9]. 4.4 Transition Times

  5. Dynamic response of a single-walled carbon nanotube under a moving harmonic load by considering modified nonlocal elasticity theory

    Science.gov (United States)

    Rahmani, O.; Shokrnia, M.; Golmohammadi, H.; Hosseini, S. A. H.

    2018-02-01

    Transverse forced vibration of a single-walled carbon nanotube (SWCNT) under excitation of a moving harmonic load has been analyzed based on modified nonlocal elasticity theory. In the parametric study, influences of nonlocal parameter, velocity of the moving load, excitation frequency, order of derivative and their interactive effects on forced deflection of the nanotube have been investigated in details. Numerical amounts of the dimensionless static deflection of the SWCNT have been calculated and compared with those of existing papers and an excellent agreement has been achieved. The results show that the variation of N affects the dynamic deflection and natural frequency of SWCNTs, significantly. Also by amplification of the excitation frequency, differences between the amounts of dynamic deflection become smaller for various values of N . Furthermore, decreasing the frequency ratio causes a reduction of the maximum deflection and increasing the frequency ratio causes an increase of the maximum deflection for values of load velocity which are greater than a specified value.

  6. Synthesis of Single-Walled Carbon Nanotubes: Effects of Active Metals, Catalyst Supports, and Metal Loading Percentage

    Directory of Open Access Journals (Sweden)

    Wei-Wen Liu

    2013-01-01

    Full Text Available The effects of active metals, catalyst supports, and metal loading percentage on the formation of single-walled carbon nanotubes (SWNTs were studied. In particular, iron, cobalt, and nickel were investigated for SWNTs synthesis. Iron was found to grow better-quality SWNTs compared to cobalt and nickel. To study the effect of catalyst supports, magnesium oxide, silicon oxide, and aluminium oxide were chosen for iron. Among the studied supports, MgO was identified to be a suitable support for iron as it produced SWNTs with better graphitisation determined by Raman analysis. Increasing the iron loading decreased the quality of SWNTs due to extensive agglomeration of the iron particles. Thus, lower metal loading percentage is preferred to grow better-quality SWNTs with uniform diameters.

  7. Single and multi degree of freedom analysis of steel beams under blast loading

    International Nuclear Information System (INIS)

    Nassr, Amr A.; Razaqpur, A. Ghani; Tait, Michael J.; Campidelli, Manuel; Foo, Simon

    2012-01-01

    Highlights: ► Experimentally tested beams under blast are analyzed using SDOF and MDOF models. ► SDOF model adequately captures the time dependant deformations and internal forces. ► Constant DIF based on a low strain rate leads to conservative estimate of the DIF. ► The responses of the test beams are governed by the first mode of vibration. - Abstract: This paper presents detailed analysis of the results of field tests on 13 full scale wide flange steel beams subjected to blast loads generated by the detonation of up to 250 kg of ANFO explosive. The experimental results are analyzed using an equivalent Single-Degree-of-Freedom (SDOF) model of a beam, which includes material nonlinearity and strain rate effects. To account for strain rate effect on beam stiffness and strength, its full moment-curvature response is determined by dividing its cross-section into a number of layers and a strain rate-dependent stress-strain relationship, based on the Cowper–Symonds strain rate model, is used to capture the nonlinear stress distribution over the section. To determine the effects of higher modes of vibration and the variation of beam mechanical properties along its length on its dynamic response, the test beams are also analyzed using a Multi-Degree-of-Freedom (MDOF) model involving beam finite elements. Each element has two nodes and three degrees of freedom and is again divided into a number of layers to capture the strain rate effect and nonlinear stress distribution over its depth. The predicted displacements and strains by the two models are compared with the corresponding experimental data and the results show that for the given beams, the time-dependant deformations, internal forces, and moments can be adequately predicted by either model because the first mode of vibration is found to dominate their response; however, the use of a constant strain rate through the so-called Dynamic Increase Factor (DIF) can lead to highly conservative estimate of the

  8. Performance enhancement of the single-phase series active filter by employing the load voltage waveform reconstruction and line current sampling delay reduction methods

    DEFF Research Database (Denmark)

    Senturk, O.S.; Hava, A.M.

    2011-01-01

    This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...

  9. Modeling pulsations in hot stars with winds

    Energy Technology Data Exchange (ETDEWEB)

    Noels, Arlette; Godart, Melanie [Institut d' Astrophysique et de Geophysique, Liege (Belgium); Dupret, Marc-Antoine [Observatoire de Paris-Meudon, LESIA (France)], E-mail: Arlette.Noels@ulg.ac.be, E-mail: ma.dupret@obspm.fr, E-mail: Melanie.Godart@ulg.ac.be

    2008-10-15

    The interaction pulsation/mass loss takes different aspects. Pulsations can trigger mass loss as in LBVs and Miras; on the other hand, mass loss can modify the driving conditions within the stars. But the most spectacular aspect is the effect on stellar models which, in turn, opens a royal way to asteroseismology to test physical conditions inside massive stars, such as the extent of convective cores or the appearance of new driving mechanisms. We start with a discussion on MS stars and their strange mode instabilities. We then move on to the excitation of the LBV phenomenon. WR stars and the newly observed MOST period in WR123 are discussed in view of the power of asteroseismology. We then turn to B supergiants, in particular HD163899, and show how asteroseismology can really probe convection, semiconvection and mass loss.

  10. Stellar pulsations in beyond Horndeski gravity theories

    Science.gov (United States)

    Sakstein, Jeremy; Kenna-Allison, Michael; Koyama, Kazuya

    2017-03-01

    Theories of gravity in the beyond Horndeski class recover the predictions of general relativity in the solar system whilst admitting novel cosmologies, including late-time de Sitter solutions in the absence of a cosmological constant. Deviations from Newton's law are predicted inside astrophysical bodies, which allow for falsifiable, smoking-gun tests of the theory. In this work we study the pulsations of stars by deriving and solving the wave equation governing linear adiabatic oscillations to find the modified period of pulsation. Using both semi-analytic and numerical models, we perform a preliminary survey of the stellar zoo in an attempt to identify the best candidate objects for testing the theory. Brown dwarfs and Cepheid stars are found to be particularly sensitive objects and we discuss the possibility of using both to test the theory.

  11. Bringing Pulsating Stars Into the Physics Classroom

    Science.gov (United States)

    Carroll, B. W.; Ostlie, D. A.

    2000-12-01

    Undergraduate physics students at many institutions are never exposed to any aspect of theoretical astrophysics. This is doubly unfortunate because students then miss the opportunity to integrate their knowledge of several disciplines and apply it to interesting astrophysical phenomena. Students find pulsating stars inherently interesting, even more so when the role of these stars in determining cosmological distances is explained. Delta Cephei is such a star, with a pulsation period of 5 days, 8 hours, 48 minutes. Introductory physics students can combine the equations of gravitation and adiabatic gas processes with Newton's 2nd law to produce a simple numerical model of Delta Cephei that precisely reproduces its period. Graphs of the oscillations are distinctly nonsinusoidal. Student curiosity about where the period is ``hiding'' in the equations can lead to the technique of linearization and a discussion of how small departures from stable equilibrium result in simple harmonic motion. This work is supported by the Department of Physics at Weber State University.

  12. Stellar pulsations in beyond Horndeski gravity theories

    Energy Technology Data Exchange (ETDEWEB)

    Sakstein, Jeremy [Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania, 209 S. 33rd St., Philadelphia, PA 19104 (United States); Kenna-Allison, Michael; Koyama, Kazuya, E-mail: sakstein@physics.upenn.edu, E-mail: mka1g13@soton.ac.uk, E-mail: kazuya.koyama@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom)

    2017-03-01

    Theories of gravity in the beyond Horndeski class recover the predictions of general relativity in the solar system whilst admitting novel cosmologies, including late-time de Sitter solutions in the absence of a cosmological constant. Deviations from Newton's law are predicted inside astrophysical bodies, which allow for falsifiable, smoking-gun tests of the theory. In this work we study the pulsations of stars by deriving and solving the wave equation governing linear adiabatic oscillations to find the modified period of pulsation. Using both semi-analytic and numerical models, we perform a preliminary survey of the stellar zoo in an attempt to identify the best candidate objects for testing the theory. Brown dwarfs and Cepheid stars are found to be particularly sensitive objects and we discuss the possibility of using both to test the theory.

  13. Constraints on stellar evolution from pulsations

    International Nuclear Information System (INIS)

    Cox, A.N.

    1984-01-01

    Consideration of the many types of intrinsic variable stars, that is, those that pulsate, reveals that perhaps a dozen classes can indicate some constraints that affect the results of stellar evolution calculations, or some interpretations of observations. Many of these constraints are not very strong or may not even be well defined yet. The author discusses the case for six classes: classical Cepheids with their measured Wesselink radii, the observed surface effective temperatures of the known eleven double-mode Cepheids, the pulsation periods and measured surface effective temperatures of three R CrB variables, the delta Scuti variable VZ Cnc with a very large ratio of its two observed periods, the nonradial oscillations of the Sun, and the period ratios of the newly discovered double-mode RR Lyrae variables. (Auth.)

  14. Modeling pulsations in hot stars with winds

    International Nuclear Information System (INIS)

    Noels, Arlette; Godart, Melanie; Dupret, Marc-Antoine

    2008-01-01

    The interaction pulsation/mass loss takes different aspects. Pulsations can trigger mass loss as in LBVs and Miras; on the other hand, mass loss can modify the driving conditions within the stars. But the most spectacular aspect is the effect on stellar models which, in turn, opens a royal way to asteroseismology to test physical conditions inside massive stars, such as the extent of convective cores or the appearance of new driving mechanisms. We start with a discussion on MS stars and their strange mode instabilities. We then move on to the excitation of the LBV phenomenon. WR stars and the newly observed MOST period in WR123 are discussed in view of the power of asteroseismology. We then turn to B supergiants, in particular HD163899, and show how asteroseismology can really probe convection, semiconvection and mass loss.

  15. Erosion of metals by pulsating water jet

    Czech Academy of Sciences Publication Activity Database

    Foldyna, Josef; Klich, Jiří; Hlaváček, Petr; Zeleňák, M.; Ščučka, Jiří

    2012-01-01

    Roč. 2, č. 19 (2012), s. 381-386 ISSN 1330-3651 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : erosion effects * pulsating water jet * surface characteristics Subject RIV: JQ - Machines ; Tools Impact factor: 0.601, year: 2012 http://hrcak.srce.hr/index.php?show=clanak&id_clanak_jezik=124846

  16. Nonradial pulsations of hot evolved stars

    International Nuclear Information System (INIS)

    Starrfield, S.G.

    1987-01-01

    There are three classes of faint blue variable stars: the ZZ Ceti variables (DAV degenerate dwarfs), the DBV variables (DB degenerate dwarfs), and the GW Vir variables (DOV degenerate dwarfs). None of these classes of variable stars were known at the time of the last blue star meeting. Observational and theoretical studies of the ZZ Ceti variables, the DBV variables, and the GW Vir variables have shown them to be pulsating in nonradial g-modes. The cause of the pulsation has been determined for each class of variable star and, in all cases, also involves predictions of the stars envelope composition. The predictions are that the ZZ Ceti variables must have pure hydrogen surface layers, the DBV stars must have pure helium surface layers, and the GW Vir stars must have carbon and oxygen rich surface layers with less than 30% (by mass) of helium. Given these compositions, it is found that pulsation driving occurs as a result of the kappa and gamma effects operating in the partial ionization zones of either hydrogen or helium. In addition, a new driving mechanism, called convection blocking, also occurs in these variables. For the GW Vir variables, it is the kappa and gamma effects in the partial ionization regions of carbon and oxygen. 45 refs

  17. A Prospective Study of Early Loaded Single Implant-Retained Mandibular Overdentures: Preliminary One-Year Results

    Directory of Open Access Journals (Sweden)

    Ali M. El-Sheikh

    2012-01-01

    Full Text Available Purpose. To investigate the predictability of simplifying mandibular overdenture treatment using one-stage surgery and early prosthetic loading of a single implant. Materials and Methods. Twenty edentulous patients with problematic existing mandibular dentures were treated. A single implant with a chemically modified surface (SLActive, Straumann AG, Basel, Switzerland was placed into the mandibular midline. The patients were recalled at 3, 6 and 12 months. Clinical assessments and marginal bone loss using standardized radiographs were recorded. All complications, failures and maintenance were noted. Visual analog-scale questionnaires were used to record patient satisfaction in five categories. ANOVA was used to determine differences between means of marginal bone loss and different categories of patient staisfaction (=0.05. Results. The 20 early loaded implants were all surviving at the 12-month recall. All implants showed less than 1 mm of marginal bone loss by the end of the 1-year with a significant increase during the follow-up period. Few prosthetic problems were reported. Patient satisfaction was high with a significant increase in all comfort and functional parameters. Conclusions. These preliminary 1-year results indicate that early loading of a single chemically modified surface implant used to retain a mucosa-borne mandibular overdenture is a safe, reliable, and cost-effective treatment.

  18. A dynamic film model of the pulsating heat pipe

    International Nuclear Information System (INIS)

    Nikolayev, Vadim S.

    2011-01-01

    This article deals with the numerical modeling of the pulsating heat pipe (PHP) and is based on the film evaporation/condensation model recently applied to the single-bubble PHP (Das et al., 2010, 'Thermally Induced Two-Phase Oscillating Flow Inside a Capillary Tube', Int. J. Heat Mass Transfer, 53(19-20), pp. 3905-3913). The described numerical code can treat the PHP of an arbitrary number of bubbles and branches. Several phenomena that occur inside the PHP are taken into account: coalescence of liquid plugs, film junction or rupture, etc. The model reproduces some of the experimentally observed regimes of functioning of the PHP such as chaotic or intermittent oscillations of large amplitudes. Some results on the PHP heat transfer are discussed. (author)

  19. Transition from pulsating to rocking localized structures in nonlinear dissipative distributive media with global inhibition

    Science.gov (United States)

    Niedernostheide, F.-J.; Dohmen, R.; Willebrand, H.; Kerner, B. S.; Purwins, H. G.

    1993-12-01

    We consider localized structures generated in a certain of two component reaction-diffusion system. Four different electric systems, namely reverse-biased p-n diodes, p-n-p transistors, a gas-discharge system, and an electrical network are recapitulated and it is shown that, in spite of the existence of different underlying physical mechanisms, in all cases an activator-inhibitor system is realized. If these systems are driven by an external voltage source via a load resistor, the equation for the external circuit leads to the appearance of an integral term in the reaction terms causing a nonlocal additional inhibiting component. Numerical calculations of the equation's system with the simplest reaction terms show exemplarily that there is a critical value of the load resistor in such systems: While below this critical value besides static only pulsating localized structures appear, for values larger than the critical one instead of pulsating only rocking localized structures can be stabilized. Near the critical resistor value we observe patterns composed of pulsating and rocking modes.

  20. Contamination of RR Lyrae stars from Binary Evolution Pulsators

    Science.gov (United States)

    Karczmarek, Paulina; Pietrzyński, Grzegorz; Belczyński, Krzysztof; Stępień, Kazimierz; Wiktorowicz, Grzegorz; Iłkiewicz, Krystian

    2016-06-01

    Binary Evolution Pulsator (BEP) is an extremely low-mass member of a binary system, which pulsates as a result of a former mass transfer to its companion. BEP mimics RR Lyrae-type pulsations but has different internal structure and evolution history. We present possible evolution channels to produce BEPs, and evaluate the contamination value, i.e. how many objects classified as RR Lyrae stars can be undetected BEPs. In this analysis we use population synthesis code StarTrack.

  1. Analysis of an adhesively bonded single lap joint subjected to eccentric loading

    DEFF Research Database (Denmark)

    Anyfantis, Konstantinos; Tsouvalis, N. G.

    2013-01-01

    A new experimental test is proposed, which allows the contribution of Mode I, II and III fracture modes to the failure of the adhesive layer of bonded joints aiming at achieving the realistic conditions often occurring during loading of practical joints. The main objective of this test is benchma......A new experimental test is proposed, which allows the contribution of Mode I, II and III fracture modes to the failure of the adhesive layer of bonded joints aiming at achieving the realistic conditions often occurring during loading of practical joints. The main objective of this test......, which correspond to Mode I, II and III loading and fracture. These tests were designed so that the metal substrates do not enter plasticity and the adhesive achieves a mode mixity ratio between Mode II and Mode III not lower than 0.5. The experiments were simulated in a 3-dimensional finite element...

  2. 33 second X-ray pulsations in AE Aquarii

    Science.gov (United States)

    Patterson, J.; Branch, D.; Chincarini, G.; Robinson, E. L.

    1980-01-01

    The discovery of 33-s pulsations in the 0.1-4.0 keV light curve of the nova-like variable AE Aquarii is reported. These pulsations agree in period and phase with the optical pulsations. The periodicity probably originated from an accretion-induced hot spot on a rapidly rotating, magnetized white dwarf. It is possible that transient pulsations at nearby periods, similar to those seen in the optical light curve, are also present in the X-ray light curve.

  3. TV morphology of some episodes of pulsating auroras

    International Nuclear Information System (INIS)

    Vallance Jones, A.; Gattinger, R.L.

    1981-01-01

    Sets of all-sky TV images of pulsating auroras obtained during the displays through which the sounding rockets of the Pulsating Aurora Campaign were fired are presented and discussed. It is emphasized that these displays are considerably more complex and variable than might seem to be the case on the basis of zenith photometer records. The pulsation modulation pattern was observed to be travelling westward during the first flight; later in the same display this apparent motion ceased. For the second flight the pulsation modulation pattern was almost stationary. (auth)

  4. Musical scale estimation for some multiperiodic pulsating stars

    Science.gov (United States)

    Ulaş, B.

    2009-03-01

    The agreement between frequency arrangements of some multiperiodic pulsating stars and musical scales is investigated in this study. The ratios of individual pulsation frequencies of 28 samples of various types of pulsating stars are compared to 57 musical scales by using two different methods. The residual sum of squares of stellar observational frequency ratios is chosen as the indicator of the accordance. The result shows that the arrangements of pulsation frequencies of Y Cam and HD 105458 are similar to Diminished Whole Tone Scale and Arabian(b) Scale, respectively.

  5. 3D finite element analysis of immediate loading of single wide versus double implants for replacing mandibular molar

    Directory of Open Access Journals (Sweden)

    Shrikar R Desai

    2013-01-01

    Full Text Available Purpose: The purpose of this finite element study was to compare the stresses, strains, and displacements of double versus single implant in immediate loading for replacing mandibular molar. Materials and Methods: Two 3D FEM (finite element method models were made to simulate implant designs. The first model used 5-mm-wide diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Anisotropic properties were assigned to bone model. Each model was analyzed with single force magnitude (100 N in vertical axis. Results: This FEM study suggested that micromotion can be controlled better for double implants compared to single wide-diameter implants. The Von Mises stress for double implant showed 74.44% stress reduction compared to that of 5-mm implant. The Von Mises elastic strain was reduced by 61% for double implant compared to 5-mm implant. Conclusion: Within the limitations of the study, when the mesiodistal space for artificial tooth is more than 12.5 mm, under immediate loading, the double implant support should be considered.

  6. 3D finite element analysis of immediate loading of single wide versus double implants for replacing mandibular molar

    Science.gov (United States)

    Desai, Shrikar R.; Karthikeyan, I.; Gaddale, Reetika

    2013-01-01

    Purpose: The purpose of this finite element study was to compare the stresses, strains, and displacements of double versus single implant in immediate loading for replacing mandibular molar. Materials and Methods: Two 3D FEM (finite element method) models were made to simulate implant designs. The first model used 5-mm-wide diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Anisotropic properties were assigned to bone model. Each model was analyzed with single force magnitude (100 N) in vertical axis. Results: This FEM study suggested that micromotion can be controlled better for double implants compared to single wide-diameter implants. The Von Mises stress for double implant showed 74.44% stress reduction compared to that of 5-mm implant. The Von Mises elastic strain was reduced by 61% for double implant compared to 5-mm implant. Conclusion: Within the limitations of the study, when the mesiodistal space for artificial tooth is more than 12.5 mm, under immediate loading, the double implant support should be considered. PMID:24554890

  7. First Kepler results on compact pulsators - V. Slowly pulsating subdwarf B stars in short-period binaries

    DEFF Research Database (Denmark)

    Kawaler, Stephen D.; Reed, Michael D.; Østensen, Roy H.

    2010-01-01

    The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for non-radial pulsations. We present our analysis of two sdB stars that are found to be g-mode pulsators of the V1093 Her class. These two stars also display the distinct irradiation effect typical o...... spacings that are suggestive of high-overtone g-mode pulsations....

  8. Divertor power load studies for attached L-mode single-null plasmas in TCV

    NARCIS (Netherlands)

    Maurizio, R.; Elmore, S.; Fedorczak, N.; Gallo, A.; Reimerdes, H.; Labit, B.; Theiler, C.; Tsui, C. K.; Vijvers, W. A. J.; TCV team,; MST1 Team,

    2018-01-01

    This paper investigates the power loads at the inner and outer divertor targets of attached, Ohmic L-mode, deuterium plasmas in the TCV tokamak, in various experimental situations using an Infrared thermography system. The study comprises variations of the outer divertor leg length and target flux

  9. Single-Mode to Multi-Mode Crossover in Thin-Load Polymethyl Methacrylate Plasmonic Waveguides

    DEFF Research Database (Denmark)

    Großmann, Malte; Thomaschewski, Martin; Klick, Alwin

    2018-01-01

    Mode character and mode dispersion of sub-60-nm-thick polymethyl methacrylate dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) are investigated using photoemission electron microscopy and finite element method simulations. Experiment and simulation show excellent agreement and all...

  10. Edge-cracks in single crystals under monotonic and cyclic loads

    DEFF Research Database (Denmark)

    Hutchinson, J.W.; Tvergaard, Viggo

    1999-01-01

    . Plasticity is assumed to occur as slip along planes inclined at 45 degrees to the surface. Problems where slip is limited to persistent slip bands are considered side-by-side with the problem where slip is not confined. Results for both monotonic and cyclic loadings are presented, with emphasis on the crack...

  11. CALCULATION OF LOADS ON THE CONTROLS WITH HELICOPTER MAIN ROTOR OF SINGLE-ROTOR DESIGN

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The article describes the method of calculation of the moments about the hinge axis of the main rotor hub from the action of aerodynamic and inertial forces generated on the blade. The assumptions were taken that the blades are absolutely rigid and have a rectangular shape in plan view. Flapping motion of blade is described accurately up to the first harmonic of the Fourier series, inductive speed is considered to be uniformly distributed over the rotor disk.The aerodynamic component of hinge moment is numerical integration of running forces on blade radius taking into account aerodynamic characteristics of the profiles received according to wind tunnel tests at different angles of attack and Mach numbers. The moment from elastic forces is determined for the main rotor hub with the lamellar torsion bar. On the basis of the hinge moments values data loads on rotorcraft rotating ring, arising at different azimuthal location of the rotating main rotor blades are calculated.The calculations executed on the example of Mi-34 helicopter main rotor have shown that average loads in one revolution in the channel of collective pitch control increase in a control path at flying speed. At the same time loads in the channel of longitudinal control make up to 80 % of loads in the channel of collective pitch control, and in the channel oflateral control - to 40 % that will well be coordinated with the provided data of flight tests.

  12. Effect of cyclic load on vertical misfit of prefabricated and cast implant single abutment

    Directory of Open Access Journals (Sweden)

    Rudys Rodolfo de Jesus Tavarez

    2011-02-01

    Full Text Available OBJECTIVES: The purpose of this in vitro study was to evaluate misfit alterations at the implant/abutment interface of external and internal connection implant systems when subjected to cyclic loading. MATERIAL AND METHODS: Standard metal crowns were fabricated for 5 groups (n=10 of implant/abutment assemblies: Group 1, external hexagon implant and UCLA cast-on premachined abutment; Group 2, internal hexagon implant and premachined abutment; Group 3, internal octagon implant and prefabricated abutment; Group 4, external hexagon implant and UCLA cast-on premachined abutment; and Group 5, external hexagon implant and Ceraone abutment. For groups 1, 2, 3 and 5, the crowns were cemented on the abutments and in group 4 crowns were screwed directly on the implant. The specimens were subjected to 500,000 cycles at 19.1 Hz of frequency and non-axial load of 133 N in a MTS 810 machine. The vertical misfit (μm at the implant/abutment interface was evaluated before (B and after (A application of the cyclic loading. Data were analyzed statistically by using two-away ANOVA and Tukey's post-hoc test (p<0.05. RESULTS: Before loading values showed no difference among groups 2 (4.33±3.13, 3 (4.79±3.43 and 5 (3.86±4.60; between groups 1 (12.88±6.43 and 4 (9.67±3.08, and among groups 2, 3 and 4. However, groups 1 and 4 were significantly different from groups 2, 3 and 5. After loading values of groups 1 (17.28±8.77 and 4 (17.78±10.99 were significantly different from those of groups 2 (4.83±4.50, 3 (8.07±4.31 and 5 (3.81±4.84. There was a significant increase in misfit values of groups 1, 3 and 4 after cyclic loading, but not for groups 2 and 5. CONCLUSIONS: The cyclic loading and type of implant/abutment connection may develop a role on the vertical misfit at the implant/abutment interface.

  13. Load-bearing capacity and the recommended thickness of dental monolithic zirconia single crowns.

    Science.gov (United States)

    Sun, Ting; Zhou, Shanyu; Lai, Renfa; Liu, Ruoyu; Ma, Shuyuan; Zhou, Zhiying; Longquan, Shao

    2014-07-01

    The aim of this study was to evaluate the load bearing capacity and a reasonable thicknesss of dental monolithic zirconia crowns. Polymethyl methacrylate (PMMA) abutment tooth specimens were made by CAD/CAM technic. Monolithic zirconia crowns (MZC), monolithic lithium disilicate crowns (MLC), layered zirconia crowns (LZC) and metal ceramic crowns(MCC), of which the occlusal thickness was 1.5mm were thereafter fabricated and cemented on the abutment tooth specimens. MCC with occlusal thicknesses of 0.6mm, 0.8mm, 1.00mm, 1.2mm were also made. All specimens underwent load-to-fracture test. Weibull parameters (σ0) and (m) were calculated. Fracture modes were also evaluated. The mean fracture load was 1863.16±116.81 for MLC, 2284.77±355.60 for MCC, 2308.0±510.94 for LZC, 4109.93±610.18 for MZC (1.5mm), 3068.31±233.88 for MZC (1.2mm), 2429.88±315.03 for MZC (1.0mm), 1814.60±68.21 for MZC (0.8mm) and 1308.38±111.38 for MZC (0.6mm). The fracture load of MZC was significantly higher than MCC, LZC and MLC (P0.05). Monolithic zirconia crowns exhibit higher fracture loads than monolithic lithium disilicate crowns, layered zirconia crowns and metal ceramic crowns. The fracture resistance of monolithic zirconia crowns with a thickness of 1.0mm can be equal to metal ceramic crowns. Doubling the monolithic zirconia core from 0.6mm to 1.5mm increases the fracture resistance of this restorative system threefold. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Lateral Bearing Capacity of Single Connectors in Parallel Loaded Battens used for Truss Bracing

    DEFF Research Database (Denmark)

    Nielsen, Jacob

    In order to analyse the stiffness and the strength of joints used for battens in bracing of trusses 70 tests have been made. The joint was made by a single nail or screw located perpendicular to or at an angle to the grain direction. The single fastener joints did not fulfil the requirements for ...

  15. Preparation and functional studies of hydroxyethyl chitosan nanoparticles loaded with anti-human death receptor 5 single-chain antibody

    Directory of Open Access Journals (Sweden)

    Yang J

    2014-05-01

    Full Text Available Jingjing Yang,1,3,* Xiaoping Huang,1,3,* Fanghong Luo,1 Xiaofeng Cheng,3 Lianna Cheng,3 Bin Liu,4 Lihong Chen,2 Ruyi Hu,1,3 Chunyan Shi,1,3 Guohong Zhuang,1,3 Ping Yin2 1Anti-Cancer Research Center, Medical College, Xiamen University, Fujian, People's Republic of China, 2The Department of Pathology, Zhongshan Hospital, Xiamen University, Xiamen, People's Republic of China, 3Organ transplantation institution, Xiamen University, Xiamen, People's Republic of China, 4Jilin Vocational College of Industry and Technology, Jilin, People's Republic of China  *These authors contributed equally to this work Objective: To prepare hydroxyethyl chitosan nanoparticles loaded with anti-human death receptor 5 single-chain antibody, and study their characteristics, functions, and mechanisms of action. Materials and methods: The anti-human death receptor 5 single-chain antibody was constructed and expressed. Protein-loaded hydroxyethyl chitosan nanoparticles were prepared, and their size, morphology, particle-size distribution and surface zeta potential were measured by scanning electron microscopy and laser particle-size analysis. Mouse H22 hepatocellular carcinoma cells were cultured, and growth inhibition was examined using the CellTiter-Blue cell-viability assay. Flow cytometry and Hoechst 33342 were employed to measure cell apoptosis. Kunming mice with H22 tumor models were treated with protein-loaded hydroxyethyl chitosan nanoparticles, and their body weight and tumor size were measured, while hematoxylin and eosin staining was used to detect antitumor effects in vivo and side effects from tumors. Results: The protein-loaded hydroxyethyl chitosan nanoparticles had good stability; the zeta potential was -24.2±0.205, and the dispersion index was 0.203. The inhibition of the protein-loaded hydroxyethyl chitosan nanoparticles on H22 growth was both time- and dose-dependent. Increased expressions of active caspase 8, active caspase 3, and BAX were detected

  16. Surface acoustic load sensing using a face-shear PIN-PMN-PT single-crystal resonator.

    Science.gov (United States)

    Kim, Kyungrim; Zhang, Shujun; Jiang, Xiaoning

    2012-11-01

    Pb(In(0.5)Nb(0.5))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) resonators for surface acoustic load sensing are presented in this paper. Different acoustic loads are applied to thickness mode, thickness-shear mode, and face-shear mode resonators, and the electrical impedances at resonance and anti-resonance frequencies are recorded. More than one order of magnitude higher sensitivity (ratio of electrical impedance change to surface acoustic impedance change) at the resonance is achieved for the face-shear-mode resonator compared with other resonators with the same dimensions. The Krimholtz, Leedom, and Matthaei (KLM) model is used to verify the surface acoustic loading effect on the electrical impedance spectrum of face-shear PIN-PMN-PT single-crystal resonators. The demonstrated high sensitivity of face-shear mode resonators to surface loads is promising for a broad range of applications, including artificial skin, biological and chemical sensors, touch screens, and other touch-based sensors.

  17. Contrasting Accreting White Dwarf Pulsators with the ZZ Ceti Stars

    Science.gov (United States)

    Mukadam, A. S.; Szkody, P.; Gänsicke, B. T.; Pala, A.

    2017-03-01

    Understanding the similarities and differences between the accreting white dwarf pulsators and their non-interacting counterparts, the ZZ Ceti stars, will eventually help us deduce how accretion affects pulsations. ZZ Ceti stars pulsate in a narrow instability strip in the range 10800-12300 K due to H ionization in their pure H envelopes; their pulsation characteristics depend on their temperature and stellar mass. Models of accreting white dwarfs are found to be pulsationally unstable due to the H/HeI ionization zone, and even show a second instability strip around 15000 K due to HeII ionization. Both these strips are expected to merge for a He abundance higher than 0.48 to form a broad instability strip, which is consistent with the empirical determination of 10500-16000 K. Accreting pulsators undergo outbursts, during which the white dwarf is heated to temperatures well beyond the instability strip and is observed to cease pulsations. The white dwarf then cools to quiescence in a few years as its outer layers cool more than a million times faster than the evolutionary rate. This provides us with an exceptional opportunity to track the evolution of pulsations from the blue edge to quiescence in a few years, while ZZ Ceti stars evolve on Myr timescales. Some accreting pulsators have also been observed to cease pulsations without any apparent evidence of an outburst. This is a distinct difference between this class of pulsators and the non-interacting ZZ Ceti stars. While the ZZ Ceti instability strip is well sampled, the strip for the accreting white dwarfs is sparsely sampled and we hereby add two new potential discoveries to improve the statistics.

  18. Soft controller switching technique to minimize the torque and current pulsations of a SCIM during its reswitching

    International Nuclear Information System (INIS)

    Larik, A.S.

    2010-01-01

    The direct-on-line starting of induction motor draws heavy current and to limit this Inrush current to a safe level normally a star-delta switch is used. However, the switching over from star to delta causes over current transients and this leads to torque pulsations. Therefore, in this paper the current and torque pulsations developed during the switching process are focused and a soft-switched controller is devised to minimize the re-closure transient currents and torque pulsations during star-delta switching of induction motor. The designed system can readily handles the sensing of favorable conditions of re closure of a switched-off running induction motor and it minimizes the inrush current and hence the pulsations of torque of all types of induction motors, whether, single-phase or three phase. An investigation is made into the transient currents and pulsation torques generated due to opening the circuit of a running induction motor and the switching pattern of star-delta switching. The re-switching control scheme for the induction motor is practically tested in the laboratory with and without soft controller. (author)

  19. About vortex-like atomic motion in a loaded single crystal

    Science.gov (United States)

    Dmitriev, A. I.; Nikonov, A. Yu.

    2017-12-01

    The paper presents a molecular dynamics study of internal stress and atomic displacement redistributions in a preliminary loaded solid. The study demonstrates the possibility of self-organized vortices as dynamic defects of typical size 1-5 nm due to atomic motion in the elastic region at the stage of relaxation. The simulation results agree well with experimental data on strain localization in elastic distortion regions which gives rise to nanodipoles of partial disclinations.

  20. Probing exotic physics with pulsating white dwarfs

    Science.gov (United States)

    Kim, Agnes

    2007-08-01

    In the present work, I combine observations of pulsating white dwarf stars with theoretical models of these stars to constrain the mass of axions and the emission rate of plasmon neutrinos (neutrinos that result from the decay of a photon coupled to a plasma). Axions, while hypothetical, are of great interest in Astrophysics because they are good candidates for the mysterious dark matter that pervades our universe. Measuring plasmon neutrino emission rates gives us a unique way to test the theory of weak interactions in the Standard Model of particles physics. Axions arise from an elegant solution to a problem with the Standard Model of particle physics. Along with supersymmetric particles, axions are currently favored candidates for dark matter. But they have not been discovered (neither have supersymmetric particles) and the theory of axions fails to place any constraint on their mass. The possible contribution of axions to dark matter depends of course on their mass. The mass of axions determines how strongly they interact with the matter we know, with more massive axions interacting more strongly. In turn, the stronger the interaction of axions with matter or light, the larger their emission rate. With pulsating white dwarfs, we can constrain the axion emission rates and therefore their mass. While we know a lot about neutrinos produced in nuclear reactions inside the Sun, plasmon decay has never been detected. This is because plasmon neutrino emission rates are expected to be significant only in very dense plasmas, such as in the degenerate interiors of white dwarfs. We cannot reproduce those conditions in the lab, and they are also not present in our nearest neutrino emitter, the Sun. Both axions and plasmon neutrinos should stream freely out of white dwarfs, contributing efficiently to their cooling. We can measure the cooling rate of pulsating white dwarfs by measuring the rate at which the pulsation period of a given mode slows down with time (P ). The

  1. The effect of platinum precursor concentrations on chlorine sensing characteristics of platinum nanoparticles-loaded single walled carbon nanotubes

    Science.gov (United States)

    Choi, Sun-Woo; Byun, Young Tae

    2018-03-01

    The correlation between platinum (Pt) functionalization and chlorine (Cl2) sensing capability in single-walled carbon nanotubes (SWCNTs) was investigated. Utilizing a photoreduction technique via ultraviolet (UV) irradiation, the Pt nanoparticles (NPs) with various diameters of 7-80 nm, which were controlled by Pt precursor concentrations, were successfully functionalized on the sidewalls of SWCNTs. The discrete Pt NP-loaded SWCNTs exhibited significantly enhanced response value (-(ΔR/R0) × 100 = 33.8%) for 1 ppm Cl2 at room temperature (25 °C) compared with that (no response) of pure SWCNTs. On the other hand, in case of continuous Pt NP-loaded SWCNTs, Cl2 sensing capabilities were significantly degraded. The Cl2 sensing capabilities of fabricated sensors tended to correlate with geometric configurations of the catalytic Pt NPs on the sidewalls of SWCNTs, due to differences in the electron pathway.

  2. A new control scheme for PID load frequency controller of single-area and multi-area power systems.

    Science.gov (United States)

    Padhan, Dola Gobinda; Majhi, Somanath

    2013-03-01

    A new control structure with a tuning method to design a PID load frequency controller for power systems is presented. Initially, the controller is designed for single area power system, then it is extended to multi-area case. The controller parameters are obtained by expanding controller transfer function using Laurent series. Relay based identification technique is adopted to estimate power system dynamics. Robustness studies on stability and performance are provided, with respect to uncertainties in the plant parameters. The proposed scheme ensures that overall system remains asymptotically stable for all bounded uncertainties and for system oscillations. Simulation results show the feasibility of the approach and the proposed method improves the load disturbance rejection performance significantly even in the presence of the uncertainties in plant parameters. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Application of PI Current Controller in Single Phase Inverter System Connected to Non Linear Load

    Science.gov (United States)

    Chai Anak Ajot, Tracy; Salimin, Suriana; Aziz, Roziah

    2017-08-01

    This study is concerned with the problem of network power quality when inverter systems are connected to a nonlinear load. Nonlinear loads are well known as one of the biggest source of harmonics in the power system. Besides that, inverter systems also have their nonlinearity characteristic because of the electronic components. As the inverter system is connected to nonlinear load, it resulting in harmonic distortion-related problem and draw non-sinusoidal currents in the system, thus reducing the power quality in the system. The application of Proportional Integral controller in this system is the main interest of this study. This current controller capable of reducing total harmonic distortion and improve the state of current waveform. This paper focuses on application of simple manual trial and error tuning technique to produce the optimum value for the gains. The result of study verifies the trial and error manual tuning of PI current controller in compensating harmonic distortions. Simulation and modelling of the system are successfully developed using Matlab/Simulink.

  4. Common bile duct motion artifacts caused by inferior vena cava pulsation on magnetic resonance cholangiopancreatography. Presidential award proceedings

    International Nuclear Information System (INIS)

    Morita, Satoru; Maruyama, Kazuhiro; Onodera, Yugo; Watanabe, Kunihiro; Suzuki, Takashi; Saito, Naoko; Mitsuhashi, Norio; Ohnishi, Takahiro; Imura, Chiaki

    2008-01-01

    The common bile duct (CBD) moves back and forth, synchronized with the inferior vena cava (IVC) pulsation depending on the cardiac cycle. We retrospectively evaluated the frequency of CBD motion artifact caused by IVC pulsation in magnetic resonance cholangiopancreatography (MRCP). The frequency of pseudo-defects in MRCP was significantly higher in patients with ghost artifact than those without, which was observed at the ventral and dorsal aspects of the CBD on multi-slice half-Fourier acquisition single-shot turbo spin-echo trans-axial (HASTE-ax) images. The present study indicates that pseudo-defects of the CBD caused by IVC pulsation are observed on MRCP. The addition of HASTE-ax images during interpretation can diminish the potential for misinterpreting this CBD motion artifact as a bile duct tumor or biliary stone. (author)

  5. Flow pulsation and network structure in mesenteric microvasculature of rats.

    Science.gov (United States)

    Seki, J

    1994-02-01

    Red cell velocity was measured by a fiber-optic laser-Doppler anemometer microscope in microvessels of the mesentery of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto control rats (WKY) with high temporal resolution. Based on the velocity data, the propagation velocity of flow pulse along single microvessels as well as the arteriovenous distributions of the mean volumetric flow, the amplitude of flow pulsation, and the phase lag of the flow relative to the systemic pressure were analyzed in relationship to the vessel wall rheology and the network topology. The propagation velocity was 3.5-134 cm/s in arterioles of 12-43 microns in diameter, and it increased with increasing diameter. The mean volumetric flow exhibited a power law relationship to the vessel diameter, in which the exponents were 3.16 and 3.30 for arterioles and 3.03 and 2.85 for venules in SHR and WKY, respectively. The exponents for arterioles were > 3 (P flow pulsation also varied in a power law with the vessel diameter, whose exponents for arterioles were 3.41 and 3.52 for SHR and WKY, respectively. The flow phase lag increased gradually with decreasing vessel diameter in arterioles and increased comparatively rapidly with increasing vessel diameter in venules, which suggests more compliant vessel walls for venules than arterioles. The slope of the increase in the flow phase lag with the vessel diameter in arterioles of SHR was larger than that for WKY (P flow phase lag distribution and the difference in the exponent of the mean flow rate vs. diameter relationship may reflect that the number of small arterioles relative to large ones is reduced in SHR microvasculature compared with that in WKY.

  6. Effect of immediate functional loading on osseointegration of implants used for single tooth replacement. A human histological study.

    Science.gov (United States)

    Donati, Mauro; Botticelli, Daniele; La Scala, Vincenzo; Tomasi, Cristiano; Berglundh, Tord

    2013-07-01

    To analyze hard tissue reactions to immediate functionally loaded single implants that were installed either with a conventional drill preparation procedure or with an osteotome preparation technique. Thirteen subjects with two sites requiring single tooth rehabilitation by means of implants volunteered for the study. Each subject received one test (immediate functionally loaded) and one control (non-loaded) implant. In six subjects (group 1) the implants were placed using a conventional drilling procedure, whereas in the remaining seven subjects (group 2) an osteotome preparation procedure was performed. Block biopsies containing test and control implants and peri-implant bone tissues were collected at 1 month in four of the subjects in group 1 and in five subjects of group 2. The remaining implant sites were sampled at 3 months after implant placement. The biopsies were prepared for histological examination. Two implants of the test-2 group (osteotome preparation) representing 1 month of healing and another test-2 implant representing 3 months of healing failed to integrate. A multilevel multivariate statistical analysis demonstrated that no differences in bone-to-implant contact (BIC)% were found in between test and control implants, the density of newly formed peri-implant bone was significantly higher around test than control implants at 1 and 3 months of healing. Sections representing osteotome technique sites showed fractured trabeculae and large amounts of bone particles. It is suggested that immediate loading of implants does not influence the osseointegration process, whereas the density of newly formed peri-implant bone at such sites appears to be increased in relation to unloaded control implants. The use of an osteotome preparation technique during installation results in damage of peri-implant bone and enhances the risk for failure in osseointegration. © 2012 John Wiley & Sons A/S.

  7. Reactive bonding mediated high mass loading of individualized single-walled carbon nanotubes in an elastomeric polymer

    Science.gov (United States)

    Zhao, Liping; Li, Yongjin; Qiu, Jishan; You, Jichun; Dong, Wenyong; Cao, Xiaojun

    2012-09-01

    A reactive chemical bonding strategy was developed for the incorporation of a high mass loading of individual single-wall carbon nanotubes (SWCNTs) into an elastomeric matrix using a reactive ionic liquid as a linker. This method simultaneously prevented the agglomeration of SWCNTs and caused strong interfacial bonding, while the electronic properties of the SWCNTs remained intact. As a result, the high conductivity of the carbon nanotubes (CNTs) and the flexibility of the elastomeric matrix were retained, producing optimum electrical and mechanical properties. A composite material with a loading of 20 wt% SWCNTs was fabricated with excellent mechanical properties and a high conductivity (9500 S m-1). The method could be used to form transparent thin conductive films that could tolerate over 800 bend cycles at a bending angle of 180° while maintaining a constant sheet resistance.A reactive chemical bonding strategy was developed for the incorporation of a high mass loading of individual single-wall carbon nanotubes (SWCNTs) into an elastomeric matrix using a reactive ionic liquid as a linker. This method simultaneously prevented the agglomeration of SWCNTs and caused strong interfacial bonding, while the electronic properties of the SWCNTs remained intact. As a result, the high conductivity of the carbon nanotubes (CNTs) and the flexibility of the elastomeric matrix were retained, producing optimum electrical and mechanical properties. A composite material with a loading of 20 wt% SWCNTs was fabricated with excellent mechanical properties and a high conductivity (9500 S m-1). The method could be used to form transparent thin conductive films that could tolerate over 800 bend cycles at a bending angle of 180° while maintaining a constant sheet resistance. Electronic supplementary information (ESI) available: Conductivity test of the SEBS-SWCNTs film, transmission spectra and sheet resistance for the spin-coated SEBS-SWCNTs thin films on PET slides. See DOI: 10

  8. Role of Inelastic Transverse Compressive Behavior and Multiaxial Loading on the Transverse Impact of Kevlar KM2 Single Fiber

    Directory of Open Access Journals (Sweden)

    Subramani Sockalingam

    2017-02-01

    Full Text Available High-velocity transverse impact of ballistic fabrics and yarns by projectiles subject individual fibers to multi-axial dynamic loading. Single-fiber transverse impact experiments with the current state-of-the-art experimental capabilities are challenging due to the associated micron length-scale. Kevlar® KM2 fibers exhibit a nonlinear inelastic behavior in transverse compression with an elastic limit less than 1.5% strain. The effect of this transverse behavior on a single KM2 fiber subjected to a cylindrical and a fragment-simulating projectile (FSP transverse impact is studied with a 3D finite element model. The inelastic behavior results in a significant reduction of fiber bounce velocity and projectile-fiber contact forces up to 38% compared to an elastic impact response. The multiaxial stress states during impact including transverse compression, axial tension, axial compression and interlaminar shear are presented at the location of failure. In addition, the models show a strain concentration over a small length in the fiber under the projectile-fiber contact. A failure criterion, based on maximum axial tensile strain accounting for the gage length, strain rate and multiaxial loading degradation effects are applied to predict the single-fiber breaking speed. Results are compared to the elastic response to assess the importance of inelastic material behavior on failure during a transverse impact.

  9. A closed pulsating universe with inner dimensionality

    Science.gov (United States)

    Tangherlini, F. R.

    The closed universe begins with a point singularity at the Big Bang and returns to a point singularity at the Big Crunch. These singularities present serious mathematical difficulties in extrapolating to times before the initial and after the final events. Such situations violate Einstein's singularity-free field theory. A possible solution to the crisis posed by gravitational collapse and the singularity problem is to regard Einstein's field equations for the problem as analogous to a dynamical system that requires stabilization. Attention is presently given to a dynamically stabilized model which views the universe as 'pulsating', with a collapse that rebounds at some minimum value of the expansion parameter.

  10. Pulsations in white dwarfs: Selected topics

    Directory of Open Access Journals (Sweden)

    Saio H.

    2013-03-01

    Full Text Available This paper presents a very brief overview of the observed properties of g-mode pulsations in variable white dwarfs. We then discuss a few selected topics: Excitation mechanisms (kappa- and convection- mechanisms, and briefly the effect of a strong magnetic field (∼ 1 MG on g-modes as recently found in a hot DQ (carbon-rich atmosphere white dwarf. In the discussion of excitation mechanisms, a simple interpretation for the convection mechanism is given.

  11. A radiographic evaluation of progressive loading on crestal and bone density changes around single osseointegrated implants in the posterior maxilla

    Directory of Open Access Journals (Sweden)

    Ommati Shabestari Gh.

    2009-11-01

    Full Text Available "nBackground and Aim: The aim of this clinical study was to determine the effectiveness of progressive loading procedures on preserving crestal bone height and improving peri-implant bone density around maxillary implants restored with single crowns by an accurate longitudinal radiographic assessment technique. "n "n "nMaterials and Methods: Eleven Micro-Thread Osseo Speed dental implants were placed in 11 subjects and permitted to heal for 6 weeks before surgical uncovering. Following an 8-week healing period, implants underwent a progressive loading protocol by increasing the height of the occlusal table in increments from adding acrylic resin to an acrylic crown. The progressively loaded crowns were placed in 2 mm infraocclusion for the first 2 months, light occlusion for the second 2 months, and full occlusion for the third 2 months. At forth 2 months, a metal ceramic crown replaced the acrylic crown. Digital radiographs of each implant were made at the time of restoration, then after 2, 4, 6, 8, and 12 months of function. Digital image analysis was done to measure changes in crestal bone height and peri-implant bone density. "n "n "nResults: The mean values of crestal bone loss at 12 months were 0.11 ± 0.19 mm, and when tested with Friedman across the time periods, the differences were not statistically significant (p> 0.05. The mean values of bone density in the crestal, middle, and apical area were tested with Repeated Measure ANOVA across the time periods, the differences were statistically significant (p<0.05. "n "n "nConclusion: Progressive loading doesn’t cause crestal bone loss. The peri-implant density measurements of the progressively loaded implants show continuous increase in crestal, middle and apical peri-implant bone density by time. "n 

  12. The Cepheid mass discrepancy and pulsation-driven mass loss

    NARCIS (Netherlands)

    Neilson, H.R.; Cantiello, M.; Langer, N.

    2011-01-01

    Context. A longstanding challenge for understanding classical Cepheids is the Cepheid mass discrepancy, where theoretical mass estimates using stellar evolution and stellar pulsation calculations have been found to differ by approximately 10−20%. Aims. We study the role of pulsation-driven mass loss

  13. Fracture mode during cyclic loading of implant-supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Kleven, Erik; Gotfredsen, Klaus

    2012-01-01

    restorations of zirconia abutment-retained crowns with zirconia copings veneered with glass-ceramics (n=8) and feldspathic ceramics (n=8). The control group was composed of 16 metal ceramic restorations of titanium abutment-retained crowns with gold alloy copings veneered with glass (n=8) and feldspathic......STATEMENT OF PROBLEM: Fracture of veneering ceramics in zirconia-based restorations has frequently been reported. Investigation of the fracture mode of implant-supported ceramic restorations by using clinically relevant laboratory protocols is needed. PURPOSE: This study compared the mode...... and resisted more cyclic loads than the ceramic restorations, particularly when the metal ceramic crowns were veneered with glass-ceramics....

  14. Realistic kinetic loading of the jaw system during single chewing cycles: a finite element study.

    Science.gov (United States)

    Martinez Choy, S E; Lenz, J; Schweizerhof, K; Schmitter, M; Schindler, H J

    2017-05-01

    Although knowledge of short-range kinetic interactions between antagonistic teeth during mastication is of essential importance for ensuring interference-free fixed dental reconstructions, little information is available. In this study, the forces on and displacements of the teeth during kinetic molar biting simulating the power stroke of a chewing cycle were investigated by use of a finite-element model that included all the essential components of the human masticatory system, including an elastic food bolus. We hypothesised that the model can approximate the loading characteristics of the dentition found in previous experimental studies. The simulation was a transient analysis, that is, it considered the dynamic behaviour of the jaw. In particular, the reaction forces on the teeth and joints arose from contact, rather than nodal forces or constraints. To compute displacements of the teeth, the periodontal ligament (PDL) was modelled by use of an Ogden material model calibrated on the basis of results obtained in previous experiments. During the initial holding phase of the power stroke, bite forces were aligned with the roots of the molars until substantial deformation of the bolus occurred. The forces tilted the molars in the bucco-lingual and mesio-distal directions, but as the intrusive force increased the teeth returned to their initial configuration. The Ogden material model used for the PDL enabled accurate prediction of the displacements observed in experimental tests. In conclusion, the comprehensive kinetic finite element model reproduced the kinematic and loading characteristics of previous experimental investigations. © 2017 John Wiley & Sons Ltd.

  15. SABRE observations of Pi2 pulsations: case studies

    Directory of Open Access Journals (Sweden)

    E. G. Bradshaw

    1997-01-01

    Full Text Available The characteristics of substorm-associated Pi2 pulsations observed by the SABRE coherent radar system during three separate case studies are presented. The SABRE field of view is well positioned to observe the differences between the auroral zone pulsation signature and that observed at mid-latitudes. During the first case study the SABRE field of view is initially in the eastward electrojet, equatorward and to the west of the substorm-enhanced electrojet current. As the interval progresses, the western, upward field-aligned current of the substorm current wedge moves westward across the longitudes of the radar field of view. The westward motion of the wedge is apparent in the spatial and temporal signatures of the associated Pi2 pulsation spectra and polarisation sense. During the second case study, the complex field-aligned and ionospheric currents associated with the pulsation generation region move equatorward into the SABRE field of view and then poleward out of it again after the third pulsation in the series. The spectral content of the four pulsations during the interval indicate different auroral zone and mid-latitude signatures. The final case study is from a period of low magnetic activity when SABRE observes a Pi2 pulsation signature from regions equatorward of the enhanced substorm currents. There is an apparent mode change between the signature observed by SABRE in the ionosphere and that on the ground by magnetometers at latitudes slightly equatorward of the radar field of view. The observations are discussed in terms of published theories of the generation mechanisms for this type of pulsation. Different signatures are observed by SABRE depending on the level of magnetic activity and the position of the SABRE field of view relative to the pulsation generation region. A twin source model for Pi2 pulsation generation provides the clearest explanation of the signatures observed.

  16. Constraints on stellar evolution from pulsations

    International Nuclear Information System (INIS)

    Cox, A.N.

    1983-01-01

    Consideration of the many types of intrinsic variable stars, that is, those that pulsate, reveals that perhaps a dozen classes can indicate some constraints that affect the results of stellar evolution calculations, or some interpretations of observations. Many of these constraints are not very strong or may not even be well defined yet. In this review we discuss only the case for six classes: classical Cepheids with their measured Wesselink radii, the observed surface effective temperatures of the known eleven double-mode Cepheids, the pulsation periods and measured surface effective temperatures of three R CrB variables, the delta Scuti variable VZ Cnc with a very large ratio of its two observed periods, the nonradial oscillations of our sun, and the period ratios of the newly discovered double-mode RR Lyrae variables. Unfortunately, the present state of knowledge about the exact compositions; mass loss and its dependence on the mass, radius, luminosity, and composition; ;and internal mixing processes, as well as sometimes the more basic parameters such as luminosities and surface effective temperatures prevent us from applying strong constraints for every case where currently the possibility exists

  17. Experiments on thermal characteristics of a natural circulation loop with latent heat energy storage under cyclic pulsed heat load

    Science.gov (United States)

    Tan, G. H.; Ho, C. J.

    An experimental investigation has been made of thermal characteristics of a rectangular, annular single-phase natural circulation loop with the inner tube filled with a solid-liquid phase change material (PCM) under cyclic pulsating heat load. A rectangular, annular loop of 150 cm in height and 75 cm in width was constructed with an annular gap of 0.6 cm, within which water was filled. The inner tube of the annular loop was filled with a PCM (n-Eicosene) or air. Under the cyclic pulsating heat load, temperature field within the water-filled annular loop with PCM- or air-filled inner tube was found to evolve into a steady periodic variation for the range of parameters considered. The water temperature and/or its fluctuating amplitude along the heated or cooled sections of the loop with the PCM-filled inner tube were found to be markedly lower than those measured in the loop with the air-filled inner tube under the identical conditions. On the other hand, along the insulated sections of the loop a somewhat minute difference in temporal variations of the water temperatures exists between the loops with PCM- and air-filled inner tube. In addition, at the outer wall along the cooled section, a time-periodic variation of temperature was detected in synchronizing with the pulsating heat load. Parametric effects of varying amplitude and time-period of the pulsating heat input, as well as of varying the inlet coolant temperature of the cooling jacket were investigated.

  18. Learning Effectiveness and Cognitive Loads in Instructional Materials of Programming Language on Single and Dual Screens

    Science.gov (United States)

    Hsu, Jenq-Muh; Chang, Ting-Wen; Yu, Pao-Ta

    2012-01-01

    The teaching and learning environment in a traditional classroom typically includes a projection screen, a projector, and a computer within a digital interactive table. Instructors may apply multimedia learning materials using various information communication technologies to increase interaction effects. However, a single screen only displays a…

  19. Pulsating stars in ω Centauri. Near-IR properties and period-luminosity relations

    Directory of Open Access Journals (Sweden)

    Navarrete Camila

    2017-01-01

    Full Text Available ω Centauri (NGC 5139 contains many variable stars of different types, including the pulsating type II Cepheids, RR Lyrae and SX Phoenicis stars. We carried out a deep, wide-field, near-infrared (IR variability survey of ω Cen, using the VISTA telescope. We assembled an unprecedented homogeneous and complete J and KS near-IR catalog of variable stars in the field of ω Cen. In this paper we compare optical and near-IR light curves of RR Lyrae stars, emphasizing the main differences. Moreover, we discuss the ability of near-IR observations to detect SX Phoenicis stars given the fact that the amplitudes are much smaller in these bands compared to the optical. Finally, we consider the case in which all the pulsating stars in the three different variability types follow a single period-luminosity relation in the near-IR bands.

  20. Decentralized Method for Load Sharing and Power Management in a Hybrid Single/Three-Phase-Islanded Microgrid Consisting of Hybrid Source PV/Battery Units

    DEFF Research Database (Denmark)

    Karimi, Yaser; Oraee, Hashem; Guerrero, Josep M.

    2017-01-01

    This paper proposes a new decentralized power management and load sharing method for a photovoltaic based, hybrid single/three-phase islanded microgrid consisting of various PV units, battery units and hybrid PV/battery units. The proposed method is not limited to the systems with separate PV...... in different load, PV generation and battery conditions is validated experimentally in a microgrid lab prototype consisted of one three-phase unit and two single-phase units....

  1. Observation of martensitic structure evolution in Cu-Al-Ni single crystals with shape memory effect under external load using photoacoustic microscopy

    International Nuclear Information System (INIS)

    Muratikov, K.L.; Glazov, A.L.; Nikolaev, V.I.; Pul'nev, S.A.

    2006-01-01

    Photoacoustic microscopy is applied to observe the surface structure of Cu-Al-Ni shape-memory single crystals in both the loaded and unloaded states. Visualizing the early stages of the loading-induced martensitic transformation in Cu-Al-Ni single crystals is demonstrated to be feasible. The photoacoustic images are distinguished to advantage from the corresponding optical images by a higher contrast between different phases of the Cu-Al-Ni shape-memory alloy [ru

  2. Design and Operation of a Cryogenic Nitrogen Pulsating Heat Pipe

    International Nuclear Information System (INIS)

    Fonseca, Luis Diego; Miller, Franklin; Pfotenhauer, John

    2015-01-01

    We report the design, experimental setup and successful test results using an innovative passive cooling system called a “Pulsating Heat Pipe” (PHP) operating at temperatures ranging from 77 K to 80 K and using nitrogen as the working fluid. PHPs, which transfer heat by two phase flow mechanisms through a closed loop tubing have the advantage that no electrical pumps are needed to drive the fluid flow. In addition, PHPs have an advantage over copper straps and thermal conductors since they are lighter in weight, exhibit lower temperature gradients and have higher heat transfer rates. PHPs consist of an evaporator section, thermally anchored to a solid, where heat is received at the saturation temperature where the liquid portion of the two-phase flow evaporates, and a condenser where heat is rejected at the saturation temperature where the vapor is condensed. The condenser section in our experiment has been thermally interfaced to a CT cryocooler from SunPower that has a cooling capacity of 10 W at 77 K. Alternating regions of liquid slugs and small vapor plugs fill the capillary tubing, with the vapor regions contracting in the condenser section and expanding in the evaporator section due to an electric heater that will generate heat loads up to 10 W. This volumetric expansion and contraction provides the oscillatory flow of the fluid throughout the capillary tubing thereby transferring heat from one end to the other. The thermal performance and temperature characteristics of the PHP will be correlated as a function of average condenser temperature, PHP fill liquid ratio, and evaporator heat load. The experimental data show that the heat transfer between the evaporator and condenser sections can produce an effective thermal conductivity up to 35000 W/m-K at a 3.5 W heat load. (paper)

  3. Survival and Complications of Single Dental Implants in the Edentulous Mandible Following Immediate or Delayed Loading: A Randomized Controlled Clinical Trial.

    Science.gov (United States)

    Kern, M; Att, W; Fritzer, E; Kappel, S; Luthardt, R G; Mundt, T; Reissmann, D R; Rädel, M; Stiesch, M; Wolfart, S; Passia, N

    2018-02-01

    It was the aim of this 24-mo randomized controlled clinical trial to investigate whether the survival of a single median implant placed in the edentulous mandible to retain a complete denture is not compromised by immediate loading. Secondary outcomes were differences in prosthetic complications between the loading principles. Each of the 158 patients who received an implant was randomly assigned to the immediate loading group ( n = 81) or the delayed loading group ( n = 77). Recall visits were performed 1 mo after implant placement (for only the delayed loading group) and 1, 4, 12, and 24 mo after implant loading. Nine implants failed in the immediate loading group, all within the first 3 mo of implant loading, and 1 implant failed in the delayed loading group prior to loading. Noninferiority of implant survival of the immediate loading group, as compared with the delayed loading group, could not be shown ( P = 0.81). Consistent with this result, a secondary analysis with Fisher exact test revealed that the observed difference in implant survival between the treatment groups was indeed statistically significant ( P = 0.019). The most frequent prosthetic complications and maintenance interventions in the mandible were retention adjustments, denture fractures, pressure sores, and matrix exchanges. There was only 1 statistically significant difference between the groups regarding the parameter "fracture of the denture base in the ball attachment area" ( P = 0.007). The results indicate that immediate loading of a single implant in the edentulous mandible reveals inferior survival than that of delayed loading and therefore should be considered only in exceptional cases (German Clinical Trials Register: DRKS00003730).

  4. Single-bunch beam loading on the SLAC two-mile accelerator

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1976-05-01

    The experiments described were initially prompted by interest in the radiation loss of relativistic electron rings passing through periodic structures. Later the same experiments became relevant to the theory of energy loss of electrons in large storage rings. In both of these cases energy loss to the higher order modes of the respective structures could seriously limit their effective operation. In these experiments, single bunches of electrons with intensities up to 7 x 10 8 electrons per bunch are accelerated through the SLAC three-kilometer accelerator, and their energy spectra are analyzed. Early experiments over a wide energy range (900 MeV to 19 GeV) demonstrated that the energy loss was proportional to the total charge in the bunch but was independent of beam energy. The average energy loss of a single bunch normalized to 10 9 electrons was initially measured to be 38 MeV

  5. Immediate placement and loading of maxillary single-tooth implants: a 3-year prospective study of marginal bone level.

    Science.gov (United States)

    Berberi, Antoine N; Noujeim, Ziad N; Kanj, Wasf H; Mearawi, Rita J; Salameh, Ziad A

    2014-03-01

    The purpose of this study was to evaluate marginal bone level around single-tooth implants placed in anterior maxilla and immediately restored. Twenty implants were placed in 20 patients (8 men and 12 women) that were selected for this study. Following atraumatic non-surgical extraction of tooth, all patients immediately received implants and the definitive prefabricated abutment was placed. Implant position was transferred to the scanning unit of the CAD/CAM system using prefabricated surgical guide. Temporary crowns were immediately fabricated and cemented. Eight weeks later final crowns were luted. Outcome assessment as implant survival and level of marginal bone radiographic evaluations were performed at 8 weeks, 1 and 3 years time period after loading. All implants placed osseointegrated successfully after 3 years of functional loading. The mean marginal bone loss was 0.16 mm (SD, 0.167 mm), 0.275 mm (SD, 0.171 mm) and 0.265 mm (SD, 0.171 mm) at 8 weeks, 1 and 3 years time period respectively. Four out of the 20 implants showed no bone loss. Immediate loading technique using the final abutment directly eliminated the need for a second stage surgery and prevented interruption of soft and hard tissue at implant neck, which resulted in better soft tissue response and reduced marginal bone loss. Clinical significance: Immediately loaded implants, in fresh extraction sockets by insertion of a provisional restoration on the titanium abutment without any later manipulation, helped to protect the initially forming blood clot and presented a template for soft tissue contouring that resulted in significant reduction of marginal bone resorption and maintenance of soft tissue architecture.

  6. Clinical evaluation of a novel dental implant system as single implants under immediate loading conditions - 4-month post-loading results from a multicentre randomised controlled trial.

    Science.gov (United States)

    Esposito, Marco; Trullenque-Eriksson, Anna; Blasone, Rodolfo; Malaguti, Giuliano; Gaffuri, Cristiano; Caneva, Marco; Minciarelli, Armando; Luongo, Giuseppe

    To evaluate the safety and clinical effectiveness of a novel dental implant system (GENESIS Implant System, Keystone Dental, Massachusetts, USA) using another dental implant system by the same manufacturer as a control (PRIMA Implant System, Keystone Dental). A total of 53 patients requiring at least two single crowns had their sites randomised according to a split-mouth design to receive both implant systems at six centres. If implants could be placed with a torque superior to 40 Ncm they were to be loaded immediately with provisional crowns, otherwise after 3 months of submerged healing. Provisional crowns were replaced by definitive crowns 4 months after initial loading, when the follow-up period for the initial part of this study was completed. Outcome measures were crown/implant failures, complications, pink esthetic score (PES), peri-implant marginal bone level changes, plaque score, marginal bleeding, patients and preference of the clinician. In total 53 PRIMA and 53 GENESIS implants were placed. Three patients dropped out but all of the remaining patients were followed up to 4-months post-loading. No PRIMA implant failed whereas four GENESIS implants failed. Only two complications were reported for PRIMA implants. There were no statistically significant differences for crown/implant failures (difference in proportions = 0.080; P (McNemar test) = 0.125) and complications (difference in proportions = -0.04; P (McNemar test) = 0.500) between the implant systems. There were no differences at 4-months post-loading for plaque (difference = -0.54, 95% CI: -3.01 to 1.93; P (Paired t-test) = 0.660), marginal bleeding (difference = -3.8, 95% CI: -7.63 to 0.019; P (Paired t-test) = 0.051), PES (difference = 0.47, 95% CI: -0.56 to 1.50; P (Paired t-test) = 0.365) and marginal bone level changes (difference in mm = -0.04, 95% CI: -0.33 to 0.26; P (Paired t-test) = 0.795). The majority of the patients (46) had no

  7. Improving the thermal integrity of new single-family detached residential buildings: Documentation for a regional database of capital costs and space conditioning load savings

    International Nuclear Information System (INIS)

    Koomey, J.G.; McMahon, J.E.; Wodley, C.

    1991-07-01

    This report summarizes the costs and space-conditioning load savings from improving new single-family building shells. It relies on survey data from the National Association of Home-builders (NAHB) to assess current insulation practices for these new buildings, and NAHB cost data (aggregated to the Federal region level) to estimate the costs of improving new single-family buildings beyond current practice. Space-conditioning load savings are estimated using a database of loads for prototype buildings developed at Lawrence Berkeley Laboratory, adjusted to reflect population-weighted average weather in each of the ten federal regions and for the nation as a whole

  8. Pulsational Modes of Mira Variables Examined through IR Interferometry

    Science.gov (United States)

    Creech-Eakman, M. J.; Thompson, R. R.; van Belle, G. T.

    1999-12-01

    We have undertaken a program with the Palomar Testbed Interferometer (PTI) to measure the angular size variations, with respect to pulsational phase, of a group of about 20 mainly O-rich Mira variables. While previous groups have attempted to measure angular size with phase (van Belle et al. 1996, 1997; Tej et al. 1999) these are the first dedicated, spatially-resolved K band observations designed to detect size variations in a large sample of Miras at regular intervals over their pulsation periods. Our first goal has been the unambiguous detection of the mira pulsational cycle with phase, already shown in previous work to be as much as 35% of the radial size over the course of a pulsational period (van Belle et al. 1996; Burns et al. 1997; Tuthill et al. 1995; Perrin et al. 1999 ). We will ultimately use these data, along with the best estimates of stellar distance and effective temperatures for these sources, to determine the mode of pulsation. There has long been a debate as to whether Mira variables pulsate in their fundamental or first-overtone mode (Barthes 1999; Feast 1998; Wood and Sebo 1996). Determination of the pulsation behavior of Mira variables may eventually render them suitable as standard candles for distance determination.

  9. New pulsating casing collar to improve cementing quality

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [Southwest Petroleum Inst., Nanchong, Sichuan (China); He, K. [JiangHan Petroleum Administration Bureau, Qianjiang, Hubei (China); Wu, J. [Chevron Petroleum Tech. Co., Houston, TX (United States)

    1998-12-31

    This paper presents the design and test results of a new pulsating casing collar which improves cementing quality. The new pulsating casing collar (PCC) is designed according to the Helmholtz oscillator to generate a pulsating jet flow by self-excitation in the cementing process. By placing this new pulsating casing collar at the bottom of casing string, the generated pulsating jet flow transmits vibrating pressure waves up through the annulus and helps remove drilling mud in the annulus. It can therefore improve cementing quality, especially when eccentric annulus exists due to casing eccentricity where the mud is difficult to remove. The new pulsating casing collar consists of a top nozzle, a resonant chamber, and a bottom nozzle. It can be manufactured easily and is easy to use in the field. It has been tested in Jianghan oil-field, P.R. China. The field-test results support the theoretical analysis and laboratory test, and the cementing quality is shown greatly improved by using the new pulsating casing collar.

  10. The ionospheric signature of Pi 2 pulsations observed by STARE

    International Nuclear Information System (INIS)

    Sutcliffe, P.R.; Nielsen, E.

    1992-01-01

    This study extends the work of Sutcliffe and Nielsen (1990) in which a classical Pi 2 pulsation was first isolated in Scandinavian Twin Auroral Radar Experiment (STARE) data. A high-pass-filtering technique is used to remove the background electric field in the STARE data and so reveal the spatial and temporal ionospheric signatures of the Pi 2 pulsation electric fields. A number of events are identified and examples presented in which pulsation electric fields up to 50 mV/m are observed. Magnetic field oscillations computed from the filtered STARE data using the Biot-Savart law correlate well with pulsation magnetometer data. A 180 degree phase difference is observed between high- and low-altitude X component pulsations. The ionospheric signature of a Pi 2 is located slightly poleward of the core of the auroral breakup region where the southward, westward, and northward directed background electric fields coverage; the strongest pulsation fields occur in the region of equatorward directed electric fields. The ionospheric electric field patterns of the Pi 2 pulsations determined from the STARE data correlate well with those modeled for a transverse Alfven wave incident on an east-west aligned high-conductivity strip in the ionosphere

  11. Responses of peptide-specific T cells to stimulation with polystyrene beads carrying HLA class I molecules loaded with single peptides.

    Science.gov (United States)

    Chersi, Alberto; Galati, Rossella; Accapezzato, Daniele; Francavilla, Vittorio; Barnaba, Vincenzo; Butler, Richard H; Tanigaki, Nobuyuki

    2004-08-01

    Cell-sized microbeads carrying single peptide-loaded HLA class I molecules were prepared for HLA-A2 and HLA-B7 by a simple procedure which transfers single peptide-loaded HLA class I molecules from cultured cells to polystyrene beads using anti-peptide antibodies directed to an intracellular segment of HLA-A alpha chains. The surface density of peptide-loaded HLA class I molecules on beads was comparable to that on the peptide-loaded cells. HLA-A2 beads loaded with an HCV peptide HCV1073 were tested for stimulation activity on an HCV1073-specific CD8+ T cell clone NS3-1. A substantial level of gamma-IFN production was induced. The stimulation was peptide-specific. The efficiency was dependent on the bead concentration and the surface HLA class I density on beads and enhanced significantly by co-coupling of anti-CD28 to peptide-loaded beads. The peptide-loading efficiency on HLA class I molecules and the transfer efficiency of HLA class I molecules to polystyrene beads were reasonably high for HLA-A2 and HLA-B7. Thus, polystyrene beads carrying these single peptide-loaded HLA class I molecules are potentially useful in further analysis of the co-stimulatory or inhibitory factors involved in CD8+ T cell responses and eventually in detection of cytotoxic T cells in PBLs.

  12. The single mandibular implant study - Short-term effects of the loading protocol on Oral Health-related Quality of Life.

    Science.gov (United States)

    Schwindling, Franz Sebastian; Raedel, Michael; Passia, Nicole; Freitag-Wolf, Sandra; Wolfart, Stefan; Att, Wael; Mundt, Torsten; Reissmann, Daniel; Ismail, Fadi; von Königsmark, Valerie; Kern, Matthias

    2018-02-02

    A single implant can be placed to retain an overdenture in the edentulous mandible. This study aimed at the development of Oral Health-related Quality of Life comparing immediate and delayed implant loading, i.e., loading after 3 months of submerged healing. In a randomized controlled trial, 158 participants received a single mandibular implant in the midline. Quality of life was measured using the summary score of the German 49-item Oral Health Impact Profile at baseline, one month after implant placement (direct loading group) as well as one and four months after loading. Mean scores at baseline were comparable. Four months after implantation, a decrease of mean scores was recognized for both groups, indicating a significantly enhanced quality of life after treatment. When comparing the groups after both 1 and 4 months of loading, quality of life was insignificantly higher in the delayed loading group (1 month: 42.1 vs. 32.3; 4 months: 33.6 vs. 27.7). For immediate loading, an insignificant tendency to an earlier improvement was recognized (Δ 1month-baseline : 9.7, compared to Δ 1month-baseline : 6.4). The single mandibular implant concept was associated with a positive impact on quality of life. However, no statistically significant influence of implant loading on quality of life was found. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Interference fit effect on holed single plates loaded with tension-tension stresses

    Directory of Open Access Journals (Sweden)

    D. Croccolo

    2012-07-01

    Full Text Available This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of high performance steel (1075MPa of Ultimate strength and 990MPa of Yield strength with or without a pin, made of the same material, press fitted into their central hole. Three different conditions have been investigated: free hole specimens, specimens with 0.6% of nominal specific interference and specimens with 2% of nominal specific interference. The experimental stress-life (S–N curves pointed out an increased fatigue life of the interference fit specimens compared with the free hole ones. The numerical investigation was performed in order to analyse the stress fields by applying an elastic plastic 2D simulation with a commercial Finite Element software. The stress history and distribution along the contact interference of the fitted samples indicates a significant reduction of the local stress range due to the externally applied loading (remote stress since a residual and compressive stress field is generated by the pin insertion.

  14. Pharmacokinetic and biodistribution studies of doxorubicin-loaded single-wall carbon nanohorns in mice

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junling [China Pharmaceutical University, Department of Analytical Chemistry (China); Ma, Xiaona [Hohai University, Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment (China); Shu, Chang; Li, Nannan; Zhao, Qian; Wang, Ran; Zhong, Wenying, E-mail: wyzhong@cpu.edu.cn [China Pharmaceutical University, Department of Analytical Chemistry (China)

    2015-09-15

    Pharmacokinetic and biodistribution studies of doxorubicin-loaded carbon nanohorns (DOX@oxSWCNHs/SA) in plasma and tissues were carried out. A high-performance liquid chromatographic method was developed and validated to determine the amount of doxorubicin. Compared with free DOX, the half-life (t{sub 1/2}) of DOX@oxSWCNHs/SA was increased from 5.44 ± 1.09 to 7.38 ± 0.98 h, area under plasma concentration–time curve (AUC{sub 0–∞}) was increased from 0.63 ± 0.008 to 1.42 ± 0.12 μg/(ml h), and the clearance of DOX was declined from 634 ± 10.05 to 280 ± 24.06 ml/h. No DOX was detected in heart after intravenous injection with DOX@oxSWCNHs/SA, while higher concentrations of drug were found in other tissues. These results suggested that DOX@oxSWCNHs/SA had the potential to obtain a long retention time in blood, sustained drug release, and a low toxicity, especially low cardiotoxicity.

  15. Buoyancy effects in vertical rectangular duct with coplanar magnetic field and single sided heat load

    Science.gov (United States)

    Kostichev, P. I.; Poddubnyi, I. I.; Razuvanov, N. G.

    2017-11-01

    In some DEMO blanket designs liquid metal flows in vertical ducts of rectangular cross-section between ceramic breeder units providing their cooling. Heat exchange in these conditions is governed by the influence of magnetic field (coplanar) and by buoyancy effects that depend on the flow orientation to the gravity vector (downward and upward flow). Magnetohydrodynamic and heat transfer of liquid metal in vertical rectangular ducts is not well researched. Experimental study of buoyancy effects in rectangular duct with coplanar magnetic field for one-sided heat load and downward and upward flowsis presented in this paper. The detail research with has been done on mercury MHD close loop with using of the probe technique allow to discover several advantageous and disadvantageous effects. The intensive impact of buoyancy force has been observed in a few regime of downward flow which has been laminarized by magnetic field. Due to the development in the flow of the secondary large-scale vortices heat transfer improved and the temperature fluctuations of the abnormally high intensity have been fixed. On the contrary, in the upward flow the buoyancy force stabilized the flow which lead to decreasing of the turbulence heat transfer ratio and, consequently, deterioration of heat transfer.

  16. Immediate placement or immediate restoration/loading of single implants for molar tooth replacement: a systematic review and meta-analysis.

    Science.gov (United States)

    Atieh, Momen A; Payne, Alan G T; Duncan, Warwick J; de Silva, Rohana K; Cullinan, Mary P

    2010-01-01

    This systematic review and meta-analysis assessed the survival of immediately placed single implants in fresh molar extraction sites and immediately restored/loaded single molar implants in healed molar sites. A search of the main electronic databases, including the Cochrane Oral Health Group's Trials Register, was conducted up to November 1, 2008. The meta-analysis was prepared in accordance with the guidelines of the Academy of Osseointegration Workshop on the State of the Science on Implant Dentistry. The data were analyzed with statistical software. For immediately placed molar implants, nine studies describing 1,013 implants were included to support a survival rate of 99.0%. There were no significant differences between immediate and delayed loading/restoration in molar sites (relative risk of 0.30, 95% confidence interval 0.05 to 1.61; P = .16). For immediate restoration/loading of single implants in healed molar sites, seven studies with 188 single implants were identified. In this case, the implant survival rate was 97.9%, with no difference between immediate and delayed loading (relative risk of 3.0, 95% confidence interval: 0.33 to 27.16; P = .33). Favorable marginal bone level changes in the immediate loading group were detected at 12 months (mean difference of -0.31, 95% confidence interval: -0.53 to -0.096; P = .005). The protocols of immediate placement and immediate restoration/loading of single implants in mandibular molar regions showed encouraging results.

  17. White dwarf evolution - Cradle-to-grave constraints via pulsation

    Science.gov (United States)

    Kawaler, Steven D.

    1990-01-01

    White dwarf evolution, particularly in the early phases, is not very strongly constrained by observation. Fortunately, white dwarfs undergo nonradial pulsation in three distinct regions of the H-R diagram. These pulsations provide accurate masses, surface compositional structure and rotation velocities, and help constrain other important physical properties. We demonstrate the application of the tools of stellar seismology to white dwarf evolution using the hot white dwarf star PG 1159-035 and the cool DAV (or ZZ Ceti) stars as examples. From pulsation studies, significant challenges to the theory of white dwarf evolution emerge.

  18. Finding binaries from phase modulation of pulsating stars with Kepler

    Directory of Open Access Journals (Sweden)

    Shibahashi Hiromoto

    2017-01-01

    Full Text Available Binary orbital motion causes a periodic variation in the path length travelled by light emitted from a star towards us. Hence, if the star is pulsating, the observed phase of the pulsation varies over the orbit. Conversely, once we have observed such phase variation, we can extract information about the binary orbit from photometry alone. Continuous and precise space-based photometry has made it possible to measure these light travel time effects on the pulsating stars in binary systems. This opens up a new way of finding unseen brown dwarfs, planets, or massive compact stellar remnants: neutron stars and black holes.

  19. White dwarf evolution - Cradle-to-grave constraints via pulsation

    International Nuclear Information System (INIS)

    Kawaler, S.D.

    1990-01-01

    White dwarf evolution, particularly in the early phases, is not very strongly constrained by observation. Fortunately, white dwarfs undergo nonradial pulsation in three distinct regions of the H-R diagram. These pulsations provide accurate masses, surface compositional structure and rotation velocities, and help constrain other important physical properties. We demonstrate the application of the tools of stellar seismology to white dwarf evolution using the hot white dwarf star PG 1159-035 and the cool DAV (or ZZ Ceti) stars as examples. From pulsation studies, significant challenges to the theory of white dwarf evolution emerge. 44 refs

  20. THE PULSATION MODE OF THE CEPHEID POLARIS

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. G. [Department of Astronomy and Physics, Saint Mary' s University, Halifax NS B3H 3C3 (Canada); Kovtyukh, V. V.; Usenko, I. A. [Astronomical Observatory, Odessa National University, and Isaac Newton Institute of Chile, Odessa Branch, T. G. Shevkenko Park, 65014 Odessa (Ukraine); Gorlova, N. I., E-mail: turner@ap.smu.ca [Institute of Astronomy, Celestijnenlaan 200D, B-3001 Leuven (Belgium)

    2013-01-01

    A previously derived photometric parallax of 10.10 {+-} 0.20 mas, d = 99 {+-} 2 pc, is confirmed for Polaris by a spectroscopic parallax derived using line ratios in high dispersion spectra for the Cepheid. The resulting estimates for the mean luminosity of (M{sub V} ) = -3.07 {+-} 0.01 s.e., average effective temperature of (T{sub eff}) = 6025 {+-} 1 K s.e., and intrinsic color of ((B) - (V)){sub 0} = +0.56 {+-} 0.01 s.e., which match values obtained previously from the photometric parallax for a space reddening of E{sub B-V} = 0.02 {+-} 0.01, are consistent with fundamental mode pulsation for Polaris and a first crossing of the instability strip, as also argued by its rapid rate of period increase. The systematically smaller Hipparcos parallax for Polaris appears discrepant by comparison.

  1. Copper alloys disintegration using pulsating water jet

    Czech Academy of Sciences Publication Activity Database

    Lehocká, D.; Klich, Jiří; Foldyna, Josef; Hloch, Sergej; Królczyk, J. B.; Cárach, J.; Krolczyk, G.

    2016-01-01

    Roč. 82, March 2016 (2016), s. 375-383 ISSN 0263-2241 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : pulsating water jet * generation of pulses * disintegration * surface morphology * copper alloys Subject RIV: JQ - Machines ; Tools Impact factor: 2.359, year: 2016 http://ac.els-cdn.com/S0263224116000154/1-s2.0-S0263224116000154-main.pdf?_tid=8f8d1de6-99e9-11e6-afbc-00000aacb362&acdnat=1477314089_59912e52847e91e2030d6a1afd09e7b2

  2. The cosmological constant and the pulsating universe.

    Science.gov (United States)

    Tangherlini, F. R.

    1991-02-01

    The author's recently described method for obtaining an upper bound for a recollapsing, closed universe with a positive cosmological constant is extended to obtain a lower bound for a negative Λ. The bounds are readily generalized to cosmologies of higher dimensions. As the radius of recollapse becomes infinite and the metric Minkowskian, the bounds shrink to zero. It is inferred that in a special relativistic theory, the cosmological term should vanish. A special relativistic proof of this is given based on requiring invariance under the "tilting" of the spacelike hypersurface. Some of the remaining problems and possible successes of the pulsating universe are also described. In the appendix, the well-known instability of the Einstein universe is briefly treated by the method used here to obtain bounds on the cosmological constant.

  3. Pulsating stars in SuperWASP

    Directory of Open Access Journals (Sweden)

    Holdsworth Daniel L.

    2017-01-01

    Full Text Available SuperWASP is one of the largest ground-based surveys for transiting exoplanets. To date, it has observed over 31 million stars. Such an extensive database of time resolved photometry holds the potential for extensive searches of stellar variability, and provide solid candidates for the upcoming TESS mission. Previous work by e.g. [15], [5], [12] has shown that the WASP archive provides a wealth of pulsationally variable stars. In this talk I will provide an overview of the SuperWASP project, present some of the published results from the survey, and some of the on-going work to identify key targets for the TESS mission.

  4. Voltage-Sharing Converter to Supply Single-Phase Asymmetrical Four-Level Diode-Clamped Inverter With High Power Factor Loads

    DEFF Research Database (Denmark)

    Boora, Arash A.; Nami, Alireza; Zare, Firuz

    2010-01-01

    of the load is close to unity. In this paper, a new single-inductor multi-output dc/dc converter is proposed that can control the dc-link voltages of a single-phase diode-clamped inverter asymmetrically to achieve voltage quality enhancement. The circuit of the presented converter is explained and the main...

  5. Fatigue crack growth control in pressure vessel using single peak overload and load hold at elevated temperatures

    International Nuclear Information System (INIS)

    Chen, Ling; Nakamura, Haruo; Kobayashi, Hideo

    1995-01-01

    Pressure vessels are periodically subjected to a proof test to assure structural integrity. During that period, it may be possible to control the fatigue crack growth by simultaneous heating globally or locally around a crack tip. From this viewpoint, retardation behavior of a fatigue crack due to a single peak overload at a high temperature (∼300degC) was examined in an A 533 B-1 steel. Parameters investigated were overload ratio, applied temperature, hold time at higher temperature, and unloading temperature of overload. The higher the applied temperature, the greater the effect of retardation especially when unloading of the overload is done at lower temperatures. Also, the hold time at maximum load promotes oxide-film-induced crack closure. To evaluate those effects, a simple model is proposed based on the Dugdale model. (author)

  6. Reverse redistribution in dipyridamole-loading thallium-201 images using single photon emission computed tomography

    International Nuclear Information System (INIS)

    Mori, Kiyoo; Masuda, Masanosuke; Bunko, Hisashi.

    1986-01-01

    Dipyridamole was infused intravenously at a rate of 0.142 mg/kg per min for four min, and a stress image was obtained 10 min after the injection of two mCi 201 Tl. The myocardial image of Tl was analyzed by single photon emission computed tomography and its washout rate was calculated by the segmental ROI method. Myocardial function and the motion of the left ventricular wall were analyzed by 99m Tc-RBC-gated cardiac pool imaging. Reverse redistribution was noted in 27 (21.6 %) of 125 consecutive Tl dipyridamole and redistribution myocardial imaging studies. The stress image demonstrated normal perfusion (group 1) and reduced perfusion (group 2) of Tl. Group 1 consisted of 17 patients with diabetes mellitus, supraventricular arrhythmias, hypertension, and others. Group 2 consisted of 10 patients with subendocardial infarction, diabetes mellitus, and hypertension, and others. The percentage prevalence of reverse redistribution among patients with supraventricular arrhythmia was 62.5 % (five of eight patients), with subendocardial infarction 60.0 % (three of five), with hypertension 42.8 % (six of 14), and with diabetes mellitus 40.0 % (eight of 20), while in those with transmyocardial infarction and angina pectoris no reverse redistribution percentage was found. The washout rate of Tl in normal perfusion areas was 44.0 ± 12.8 %, the reverse redistribution of group 1 was 47.4 ± 12.8 %, and of group 2 was 51.2 ± 8.2 %. The washout rate of the reverse redistribution of group 2 was significantly greater than that of the normal areas. In gated cardiac pool imaging, patients in group 2 had significantly larger areas showing abnormal contraction of the left ventricular wall and significantly lower ejection fraction than did group 1. In the electrocardiogram ST segment depression was noted more frequently in group 2 than group 1. No Q wave was present in the corresponding reverse redistribution area. (J.P.N.)

  7. Micro-Channel Embedded Pulsating Heat Pipes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — As the need for thermal control technology becomes more demanding Micro-Channel Embedded Pulsating Heat Pipes (ME-PHPs) represents a sophisticated and enabling...

  8. Micro-Channel Embedded Pulsating Heat Pipes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As the need for thermal control technology becomes more demanding Micro-Channel Embedded Pulsating Heat Pipes (ME-PHPs) represents a sophisticated and enabling...

  9. Report of geomagnetic pulsation indices for space weather applications

    Science.gov (United States)

    Xu, Z.; Gannon, Jennifer L.; Rigler, Erin J.

    2013-01-01

    The phenomenon of ultra-low frequency geomagnetic pulsations was first observed in the ground-based measurements of the 1859 Carrington Event and has been studied for over 100 years. Pulsation frequency is considered to be “ultra” low when it is lower than the natural frequencies of the plasma, such as the ion gyrofrequency. Ultra-low frequency pulsations are considered a source of noise in some geophysical analysis techniques, such as aeromagnetic surveys and transient electromagnetics, so it is critical to develop near real-time space weather products to monitor these geomagnetic pulsations. The proper spectral analysis of magnetometer data, such as using wavelet analysis techniques, can also be important to Geomagnetically Induced Current risk assessment.

  10. Pulsating Heat Pipe for Cryogenic Fluid Management, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A passive Pulsating Heat Pipe (PHP) system is proposed to distribute cooling over broad areas with low additional system mass. The PHP technology takes advantage of...

  11. New DA white dwarf evolutionary models and their pulsational properties

    OpenAIRE

    Córsico, Alejandro Hugo; Althaus, Leandro Gabriel; Benvenuto, Omar Gustavo; Serenelli, Aldo

    2001-01-01

    In this letter we investigate the pulsational properties of ZZ Ceti stars on the basis of new white dwarf evolutionary models calculated in a self-consistent way with the predictions of time dependent element diffusion and nuclear burning. In addition, full account is taken of the evolutionary stages prior to the white dwarf formation. Emphasis is placed on the trapping properties of such models. By means of adiabatic, non-radial pulsation calculations, we find, as a result of time dependent ...

  12. GD 154: White dwarf with multi- and monoperiodic pulsation

    OpenAIRE

    Bognár Zs.; Paparó M.

    2013-01-01

    We present the white dwarf GD 154 as an example where either monoperiodic or multiperiodic pulsation were found at different epochs. The mono-multi-monoperiodic stage seems to alternate. Many questions have been raised. Is this behaviour connected to the evolution of DAV stars? How often does it happen? Is there any regularity in this change of the pulsational behaviour or is it irregular?

  13. GD 154: White dwarf with multi- and monoperiodic pulsation

    Directory of Open Access Journals (Sweden)

    Bognár Zs.

    2013-03-01

    Full Text Available We present the white dwarf GD 154 as an example where either monoperiodic or multiperiodic pulsation were found at different epochs. The mono-multi-monoperiodic stage seems to alternate. Many questions have been raised. Is this behaviour connected to the evolution of DAV stars? How often does it happen? Is there any regularity in this change of the pulsational behaviour or is it irregular?

  14. Frequency-domain analysis for pulsating combustion of gaseous fuel

    Science.gov (United States)

    Berg, I. A.; Porshnev, S. V.; Oshchepkova, V. Y.; Medvedev, A. N.

    2017-06-01

    Pulsating combustion is among combustion control methods used to suppress formation of NOx. Past experiments showed that the dependency of NOx content from pulsation rate has a minimum. A measuring unit was set up to study torch behavior in infrared band. To study pulsating combustion of gaseous fuel a thermographic camera was used. Thermographic sequences were recorded using the instrument FLIR 7700M with the resolution of 320×240 pixels at the frame rate of 412 Hz. The experiments resulted in obtaining thermographic sequences radiation intensity fields in the longitudinal section of the torch at different pulsation rates. The obtained raw data was preprocessed to obtain distributions of quantities of pixels corresponding to temperatures in each frame, as well as time-domain series for changes of the torch core longitudinal section area. Frequency-domain analysis was run for each time-domain series using Fast Fourier transform (FFT). The results demonstrate that the first maximum of spectral density coincides with the control action rate. The spectrum also contains pronounced second and third harmonics. For each spectrum of the time-domain series signal-to-noise ratio (SNR) was calculated. Comparison of different SNR shows that maximum impact of pulsation control on torch radiation intensity takes place at the on/off valve opening rate of 4 Hz. This method of torch diagnostics can be helpful for future studies and development of pulsating combustion control systems.

  15. Waveform control method for mitigating harmonics of inverter systems with nonlinear load

    DEFF Research Database (Denmark)

    Wang, Haoran; Zhu, Guorong; Fu, Xiaobin

    2015-01-01

    DC power systems connecting to single-phase DC/AC inverters with nonlinear loads will have their DC sources being injected with AC ripple currents containing a low-frequency component at twice the output voltage frequency of the inverter and also other current harmonics. Such a current may create...... ability of the waveform control method on other coexisting harmonics, while the DC source delivers AC power to a nonlinear load. With the application of the waveform control, the average DC output power is supplied by the DC source, while the other harmonics pulsation power can be confined to the AC side...... (between the capacitors and the AC load). Theoretical analyses and experiment results are provided to explain the operation and the inhibiting ability, and to showcase the performance of the approach in tackling the harmonics. Results validate that the proposed solution can achieve significant mitigation...

  16. Effects of different loading protocols on the secondary stability and peri-implant bone density of the single implants in the posterior maxilla.

    Science.gov (United States)

    Akoğlan, Mücahide; Tatli, Ufuk; Kurtoğlu, Cem; Salimov, Fariz; Kürkçü, Mehmet

    2017-08-01

    Immediate or early loading of dental implants becomes a clinically feasible concept. The aim was to evaluate the effects of different loading protocols (immediate, early, and delayed) on secondary stability and peri-implant bone density of single implants in the posterior maxilla. Thirty-nine implants (Dentium, South-Korea) were placed in 39 patients. After placement, implant stability values (ISQ) and baseline peri-implant bone density values derived from cone-beam computed tomography were recorded. Thirteen implants were included randomly in each loading groups. The secondary ISQ values were recorded during follow-up visits. Peri-implant bone density values were measured 1 year after placement again. Data was statistically analyzed. Immediate-loaded group showed the lowest ISQ values, 1 month after placement. During the next follow-up visits, delayed-loaded group showed the lowest ISQ values while other groups showed comparable results. Early loading increased the peri-implant bone density greater than the other groups. The peri-implant bone of early-loaded implants was significantly denser than that of immediate- and delayed-loaded implants, 1 year after placement. Density increment can be judged as the radiological findings of loaded-bone, which may also reduce the need for histomorphometric analysis of human biopsy to evaluate the bone reaction around the implants. © 2017 Wiley Periodicals, Inc.

  17. PULSATION FREQUENCIES AND MODES OF GIANT EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Le Bihan, Bastien [Ecole Polytechnique, Palaiseau, France. (France); Burrows, Adam, E-mail: bastien.le-bihan@polytechnique.edu, E-mail: burrows@astro.princeton.edu [Department of Astrophysical Science, Peyton Hall Princeton University, Princeton, NJ 08544 (United States)

    2013-02-10

    We calculate the eigenfrequencies and eigenfunctions of the acoustic oscillations of giant exoplanets and explore the dependence of the characteristic frequency {nu}{sub 0} and the eigenfrequencies on several parameters: the planet mass, the planet radius, the core mass, and the heavy element mass fraction in the envelope. We provide the eigenvalues for degree l up to 8 and radial order n up to 12. For the selected values of l and n, we find that the pulsation eigenfrequencies depend strongly on the planet mass and radius, especially at high frequency. We quantify this dependence through the calculation of the characteristic frequency {nu}{sub 0} which gives us an estimate of the scale of the eigenvalue spectrum at high frequency. For the mass range 0.5 M{sub J} {<=} M{sub P} {<=} 15 M{sub J} , and fixing the planet radius to the Jovian value, we find that {nu}{sub 0} {approx} 164.0 Multiplication-Sign (M{sub P} /M{sub J} ){sup 0.48}{mu}Hz, where M{sub P} is the planet mass and M{sub J} is Jupiter's mass. For the radius range from 0.9 to 2.0 R{sub J} , and fixing the planet's mass to the Jovian value, we find that {nu}{sub 0} {approx} 164.0 Multiplication-Sign (R{sub P} /R{sub J} ){sup -2.09}{mu}Hz, where R{sub P} is the planet radius and R{sub J} is Jupiter's radius. We explore the influence of the presence of a dense core on the pulsation frequencies and on the characteristic frequency of giant exoplanets. We find that the presence of heavy elements in the envelope affects the eigenvalue distribution in ways similar to the presence of a dense core. Additionally, we apply our formalism to Jupiter and Saturn and find results consistent with both the observational data of Gaulme et al. and previous theoretical work.

  18. Pulsations Induced by Vibrations in Aircraft Engine Two-Stage Pump

    Science.gov (United States)

    Gafurov, S. A.; Salmina, V. A.; Handroos, H.

    2018-01-01

    This paper describes a phenomenon of induced pressure pulsations inside a two-stage aircraft engine pump. A considered pumps consists of a screw-centrifugal and gear stages. The paper describes the cause of two-stage pump elements loading. A number of hypothesis of pressure pulsations generation inside a pump were considered. The main focus in this consideration is made on phenomena that are not related to pump mode of operation. Provided analysis has shown that pump vibrations as well as pump elements self-oscillations are the main causes that lead to trailing vortices generation. Analysis was conducted by means FEM and CFD simulations as well by means of experimental investigations to obtain natural frequencies and flow structure inside a screw-centrifugal stage. To perform accurate simulations adequate boundary conditions were considered. Cavitation and turbulence phenomena have been also taken into account. Obtained results have shown generated trailing vortices lead to high-frequency loading of the impeller of screw-centrifugal stage and can be a cause of the bearing damage.

  19. First Kepler results on compact pulsators - III. Subdwarf B stars with V1093 Her and hybrid (DW Lyn) type pulsations

    DEFF Research Database (Denmark)

    Reed, M.D.; Kawaler, Stephen D.; Østensen, Roy H.

    2010-01-01

    We present the discovery of non-radial pulsations in five hot subdwarf B (sdB) stars based on 27 d of nearly continuous time series photometry using the Kepler spacecraft. We find that every sdB star cooler than ≈27 500 K that Kepler has observed (seven so far) is a long-period pulsator of the V......1093 Her (PG 1716) class or a hybrid star with both short and long periods. The apparently non-binary long-period and hybrid pulsators are described here. The V1093 Her periods range from 1 to 4.5 h and are associated with g-mode pulsations. Three stars also exhibit short periods indicative of p......-modes with periods of 2-5 min and in addition, these stars exhibit periodicities between both classes from 15 to 45 min. We detect the coolest and longest-period V1093 Her-type pulsator to date, KIC010670103 (Teff≈ 20 900 K, Pmax≈ 4.5 h) as well as a suspected hybrid pulsator, KIC002697388, which is extremely cool...

  20. Decentralized method for load sharing and power management in a hybrid single/three-phase islanded microgrid consisting of hybrid source PV/battery units

    DEFF Research Database (Denmark)

    Karimi, Yaser; Guerrero, Josep M.; Oraee, Hashem

    2016-01-01

    This paper proposes a new decentralized power management and load sharing method for a photovoltaic based, hybrid single/three-phase islanded microgrid consisting of various PV units, battery units and hybrid PV/battery units. The proposed method takes into account the available PV power...... for switching between the states. Efficacy of the proposed method in different load, PV generation and battery conditions is validated experimentally in a microgrid lab prototype consisted of one three-phase unit and two single-phase units....

  1. Turbulent Convection and Pulsation Stability of Stars

    Science.gov (United States)

    Xiong, Da-run

    2017-10-01

    The controversies about the excitation mechanism for low-temperature variables are reviewed: (1) Most people believe that γ Doradus variables are excited by the so-called convective blocking mechanism. Our researches show that the excitation of γ Doradus has no substantial difference from that of δ Scuti. They are two subgroups of a broader type of δ Stuti-γ Doradus stars: δ Scuti is the p-mode subgroup, while γ Doradus is the g-mode subgroup. (2) Most people believe that the solar and stellar solar-like oscillations are damped by convection, and they are driven by the so-called turbulent random excitation mechanism. Our researches show that convection is not solely a damping mechanism for stellar oscillations, otherwise it is unable to explain the Mira and Mira-like variables. By using our non-local and time-dependent theory of convection, we can reproduce not only the pulsationally unstable strip of δ Scuti and γ Doradus variables, but also the solar-like oscillation features of low-luminosity red giants and the Mira-like oscillation features of high-luminosity red giants.

  2. Constraining the neutrino magnetic dipole moment from white dwarf pulsations

    International Nuclear Information System (INIS)

    Córsico, A.H.; Althaus, L.G.; Bertolami, M.M. Miller; Kepler, S.O.; García-Berro, E.

    2014-01-01

    Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment (μ ν ) using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. We employ state-of-the-art evolutionary and pulsational codes which allow us to perform a detailed asteroseismological period fit based on fully DB white dwarf evolutionary sequences. Plasmon neutrino emission is the dominant cooling mechanism for this class of hot pulsating white dwarfs, and so it is the main contributor to the rate of change of period with time (Pidot) for the DBV class. Thus, the inclusion of an anomalous neutrino emission through a non-vanishing magnetic dipole moment in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DBV stars. By comparing the theoretical Pidot value with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment with an upper limit of μ ν  ∼< 10 -11  μ B . This bound is somewhat less restrictive than, but still compatible with, other limits inferred from the white dwarf luminosity function or from the color-magnitude diagram of the Globular cluster M5. Further improvements of the measurement of the rate of period change of the dominant pulsation mode of PG 1351+489 will be necessary to confirm our bound

  3. Constraining the neutrino magnetic dipole moment from white dwarf pulsations

    Energy Technology Data Exchange (ETDEWEB)

    Córsico, A.H.; Althaus, L.G. [Grupo de Evolución Estelar y Pulsaciones, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, (1900) La Plata (Argentina); Bertolami, M.M. Miller [Instituto de Astrofísica La Plata, CONICET-UNLP, Paseo del Bosque s/n, (1900) La Plata (Argentina); Kepler, S.O. [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre 91501-970, RS (Brazil); García-Berro, E., E-mail: acorsico@fcaglp.unlp.edu.ar, E-mail: althaus@fcaglp.unlp.edu.ar, E-mail: marcelo@MPA-Garching.MPG.DE, E-mail: kepler@if.ufrgs.br, E-mail: enrique.garcia-berro@upc.edu [Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, 08860, Castelldefels (Spain)

    2014-08-01

    Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment (μ{sub ν}) using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. We employ state-of-the-art evolutionary and pulsational codes which allow us to perform a detailed asteroseismological period fit based on fully DB white dwarf evolutionary sequences. Plasmon neutrino emission is the dominant cooling mechanism for this class of hot pulsating white dwarfs, and so it is the main contributor to the rate of change of period with time (Pidot) for the DBV class. Thus, the inclusion of an anomalous neutrino emission through a non-vanishing magnetic dipole moment in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DBV stars. By comparing the theoretical Pidot value with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment with an upper limit of μ{sub ν} ∼< 10{sup -11} μ{sub B}. This bound is somewhat less restrictive than, but still compatible with, other limits inferred from the white dwarf luminosity function or from the color-magnitude diagram of the Globular cluster M5. Further improvements of the measurement of the rate of period change of the dominant pulsation mode of PG 1351+489 will be necessary to confirm our bound.

  4. KIC 6048106: an Algol-type eclipsing system with long-term magnetic activity and hybrid pulsations - I. Binary modelling

    Science.gov (United States)

    Samadi Ghadim, A.; Lampens, P.; Jassur, M.

    2018-03-01

    The A-F-type stars and pulsators (δ Scuti-γ Dor) are in a critical regime where they experience a transition from radiative to convective transport of energy in their envelopes. Such stars can pulsate in both gravity and acoustic modes. Hence, the knowledge of their fundamental parameters along with their observed pulsation characteristics can help in improving the stellar models. When residing in a binary system, these pulsators provide more accurate and less model-dependent stellar parameters than in the case of their single counterparts. We present a light-curve model for the eclipsing system KIC 6048106 based on the Kepler photometry and the code PHOEBE. We aim to obtain accurate physical parameters and tough constraints for the stellar modelling of this intermediate-mass hybrid pulsator. We performed a separate modelling of three light-curve segments which show a distinct behaviour due to a difference in activity. We also analysed the Kepler Eclipse Time Variations (ETVs). KIC 6048106 is an Algol-type binary with F5-K5 components, a near-circular orbit and a 1.56-d period undergoing variations of the order of Δ P/P˜eq 3.60× 10^{-7} in 287 ± 7 d. The primary component is a main-sequence star with M1 = 1.55 ± 0.11 M⊙, R1 = 1.57 ± 0.12 R⊙. The secondary is a much cooler subgiant with M2 = 0.33 ± 0.07 M⊙, R2 = 1.77 ± 0.16 R⊙. Many small near-polar spots are active on its surface. The second quadrature phase shows a brightness modulation on a time-scale 290 ± 7 d, in good agreement with the ETV modulation. This study reveals a stable binary configuration along with clear evidence of a long-term activity of the secondary star.

  5. Immediate Loading of Anterior Single-Tooth Implants Placed in Healed Sites: Five-Year Results of a Randomized Clinical Trial.

    Science.gov (United States)

    den Hartog, Laurens; Raghoebar, Gerry M; Stellingsma, Kees; Vissink, Arjan; Meijer, Henny Ja

    The aim of this study was to compare the 5-year outcome of immediate loading with that of conventional loading for anterior single-tooth implants placed in healed sites. It was hypothesized that immediate loading is not inferior to conventional loading. A total of 62 patients with a missing maxillary anterior tooth were included. At random, patients were treated with an implant that was restored either with a nonoccluding temporary crown within 24 hours after implant placement (immediate group) or according to a two-stage procedure after 3 months (conventional group). All implants were placed in healed sites. Follow-up visits were performed after definitive crown delivery and 1 and 5 years thereafter. Outcome measures were radiographic marginal bone level changes, implant survival, complications, soft tissue aspects (probing depth, plaque, bleeding, soft tissue level changes), esthetic outcome, and patient satisfaction. Three patients in each study group were lost to follow-up. No significant differences were found in terms of marginal bone loss (1.16 ± 0.93 mm in the immediate group and 1.20 ± 1.10 mm in the conventional group), survival (one implant lost in the immediate group), complications, soft tissue aspects, esthetic outcome, and patient satisfaction. For anterior single-tooth implants placed in healed sites, the outcome of immediate loading is not inferior to conventional loading.

  6. Pulsating flow in a planar diffuser upstream of automotive catalyst monoliths

    International Nuclear Information System (INIS)

    Mat Yamin, A.K.; Benjamin, S.F.; Roberts, C.A.

    2013-01-01

    Highlights: ► Pulsating flow is studied across catalyst monoliths placed downstream of a wide-angled diffuser. ► The ratio of pulse period to residence time within the diffuser (J factor) characterises the flow field. ► Increasing J resulted in greater flow maldistribution in the monoliths. ► Steady flow produces the highest maldistribution for a given Re. -- Abstract: The flow distribution across automotive exhaust catalysts has a significant effect on their conversion efficiency. The exhaust gas is pulsating and flow distribution is a function of engine operating condition, namely speed (frequency) and load (flow rate). This study reports on flow measurements made across catalyst monoliths placed downstream of a wide-angled planar diffuser presented with pulsating flow. Cycle-resolved particle image velocimetry (PIV) measurements were made in the diffuser and hot wire anemometry (HWA) downstream of the monoliths. The ratio of pulse period to residence time within the diffuser (defined as the J factor) characterises the flow distribution. During acceleration the flow remained attached to the diffuser walls for some distance before separating near the diffuser inlet later in the cycle. Two cases with J ∼ 3.5 resulted in very similar flow fields with the flow able to reattach downstream of the separation bubbles. With J = 6.8 separation occurred earlier with the flow field resembling, at the time of deceleration, the steady flow field. Increasing J from 3.5 to 6.8 resulted in greater flow maldistribution within the monoliths; steady flow producing the highest maldistribution in all cases for the same Re

  7. A biomechanical comparison of tendon-bone interface motion and cyclic loading between single-row, triple-loaded cuff repairs and double-row, suture-tape cuff repairs using biocomposite anchors.

    Science.gov (United States)

    Barber, F Alan; Drew, Otis R

    2012-09-01

    To compare tendon-bone interface motion and cyclic loading in a single-row, triple-loaded anchor repair with a suture-tape, rip-stop, double-row rotator cuff repair. Using 18 human shoulders from 9 matched cadaveric pairs, we created 2 groups of rotator cuff repairs. Group 1 was a double-row, rip-stop, suture-tape construct. Group 2 was a single-row, triple-loaded construct. Before mechanical testing, the supraspinatus footprint was measured with calipers. A superiorly positioned digital camera optically measured the tendon footprint motion during 60° of humeral internal and external rotation. Specimens were secured at a fixed angle not exceeding 45° in reference to the load. After preloading, each sample was cycled between 10 N and 100 N for 200 cycles at 1 Hz, followed by destructive testing at 33 mm/s. A digital camera with tracking software measured the repair displacement at 100 and 200 cycles. Ultimate load and failure mode for each sample were recorded. The exposed anterior footprint border (6.5% ± 6%) and posterior footprint border (0.9% ± 1.7%) in group 1 were statistically less than the exposed anterior footprint border (30.3% ± 17%) and posterior footprint border (29.8% ± 14%) in group 2 (P = .003 and P footprint displacements in group 1 (1.6 mm and 1.4 mm, respectively) were less than those in group 2 (both 3.6 mm) (P = .007 and P = .004, respectively). Mean displacement after 100 cycles for group 1 and group 2 was 2.0 mm and 3.2 mm, respectively, and at 200 cycles, mean displacement was 2.5 mm and 4.2 mm, respectively (P = .02). The mean ultimate failure load in group 1 (586 N) was greater than that in group 2 (393 N) (P = .02). The suture-tendon interface was the site of most construct failures. The suture-tape, rip-stop, double-row rotator cuff repair had greater footprint coverage, less rotational footprint displacement, and a greater mean ultimate failure load than the triple-loaded, single-row repair on mechanical testing. No double-row or

  8. Photometric Survey to Search for Field sdO Pulsators

    Science.gov (United States)

    Johnson, C.; Green, E.; Wallace, S.; O'Malley, C.; Amaya, H.; Biddle, L.; Fontaine, G.

    2014-04-01

    We present the results of a campaign to search for subdwarf O (sdO) star pulsators among bright field stars. The motivation for this project is the recent discovery by Randall et al. (2011) of four rapidly pulsating sdO stars in the globular cluster ω Cen, with Teff near 50,000 K, 5.4 -0.1 and similar temperatures and gravities. To date, we have found no detectable pulsations at amplitudes above 0.08% (4 times the mean noise level) in any of the 36 field sdO stars that we observed. The presence of pulsations in ω Cen sdO stars and their apparent absence in seemingly comparable field sdO stars is perplexing. While very suggestive, the significance of this result is difficult to assess more completely right now due to remaining uncertainties about the temperature width and purity of the ω Cen instability strip and the existence of any sdO pulsators with weaker amplitudes than the current detection limit in globular clusters.

  9. Some features of Pc5 pulsations during a solar cycle

    International Nuclear Information System (INIS)

    Rao, D.R.K.; Gupta, J.C.

    1978-01-01

    The morphological features of Pc5 pulsations during a solar cycle are studied using Fort Churchill data for the years 1962 to 1972. Some of the characteristics noted are as follows: (1) Increasing sunspot numbers show little influence on the diurnal variations of the occurrence, amplitude and the period except perhaps some noticeable change in the absolute magnitude of these parameters during different hours of the day. (2) The morning occurrence peak dominates during all phases of the solar cycle. (3) With increasing magnetic activity the day side region(s) of generation of Pc5 is found to shift closer to the subsolar point and in the midnight sector, the occurrence region seemed to shift towards earlier hours with increasing magnetic activity and towards later hours with increasing sunspot numbers. (4) The amplitude of Pc5 pulsations is directly related to all the levels of magnetic activity. (5) The periods of Pc5 pulsations show strong correlation with increasing sunspot numbers and the amplitude and occurrences are found to vary in accordance with the magnetic activity all through the cycle. (6) The annual and semi-annual variations of Pc5 parameters have been demonstrated especially for the pulsations occurring in the morning close to 8 +- 1 h LT and for those occurring near the midnight hours. (7) a suspected 27-day recurrence tendency has been clearly noticed for the occurrence, amplitude and period of Pc5 pulsations. (author)

  10. White dwarf variability with gPhoton: pulsators

    Science.gov (United States)

    Tucker, Michael A.; Fleming, Scott W.; Pelisoli, Ingrid; Romero, Alejandra; Bell, Keaton J.; Kepler, S. O.; Caton, Daniel B.; Debes, John; Montgomery, Michael H.; Thompson, Susan E.; Koester, Detlev; Million, Chase; Shiao, Bernie

    2018-04-01

    We present results from a search for short time-scale white dwarf variability using gPhoton, a time-tagged data base of GALEX photon events and associated software package. We conducted a survey of 320 white dwarf stars in the McCook-Sion catalogue, inspecting each for photometric variability with particular emphasis on variability over time-scales less than ˜30 min. From that survey, we present the discovery of a new pulsating white dwarf: WD 2246-069. A Ca II K line is found in archival ESO spectra and an IR excess is seen in WISE W1 and W2 bands. Its independent modes are identified in follow-up optical photometry and used to model its interior structure. Additionally, we detect UV pulsations in four previously known pulsating ZZ Ceti-type (DAVs). Included in this group is the simultaneous fitting of the pulsations of WD 1401-147 in optical, near-ultraviolet and far-ultraviolet bands using nearly concurrent Whole Earth Telescope and GALEX data, providing observational insight into the wavelength dependence of white dwarf pulsation amplitudes.

  11. Shear and foundation effects on crack root rotation and mode-mixity in moment- and force-loaded single cantilever beam sandwich specimen

    DEFF Research Database (Denmark)

    Saseendran, Vishnu; Carlsson, Leif A.; Berggreen, Christian

    2017-01-01

    Foundation effects play a crucial role in sandwich fracture specimens with a soft core. Accurate estimation of deformationcharacteristics at the crack front is vital in understanding compliance, energy release rate and mode-mixity infracture test specimens. Beam on elastic foundation analysis...... beam specimen (in contrast to themoment-loaded case), it was found that the crack length normalized energy release rate and the mode-mixity phaseangle increase strongly as the crack length decreases, a result of increased dominance of shear loading....... of moment- and force-loaded single cantilever beam sandwichfracture specimens is presented here. In addition, finite element analysis of the single cantilever beam specimen isconducted to determine displacements, rotations, energy release rate and mode-mixity. Based on finite element analysis,a foundation...

  12. Epsilon Aur monitoring during predicted pulsation phase

    Science.gov (United States)

    Waagen, Elizabeth O.; Templeton, Matthew R.

    2014-09-01

    Dr. Robert Stencel (University of Denver Astronomy Program) has requested that AAVSO observers monitor epsilon Aurigae from now through the end of the observing season. "Studies of the long-term, out-of-eclipse photometry of this enigmatic binary suggest that intervals of coherent pulsation occur at roughly 1/3 of the 27.1-year orbital period. Kloppenborg, et al. noted that stable variation patterns develop at 3,200-day intervals' implying that 'the next span of dates when such events might happen are circa JD ~2457000 (2014 December)'. "These out-of-eclipse light variations often have amplitudes of ~0.1 magnitude in U, and ~0.05 in V, with characteristic timescales of 60-100 days. The AAVSO light curve data to the present may indicate that this coherent phenomenon has begun, but we encourage renewed efforts by observers...to help deduce whether these events are internal to the F star, or externally-driven by tidal interaction with the companion star." Nightly observations or one observation every few days (CCD/PEP/DSLR, VUBR (amplitude too small for visual)) are requested. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. Epsilon Aur was the subject of major international campaigns and the AAVSO's Citizen Sky project as it went through its 27.1-year eclipse in 2009-2011. Over 700 observers worldwide submitted over 20,000 multicolor observations to the AAVSO International Database for this project. Much information on eps Aur is available from the AAVSO, including material on the Citizen Sky website (http://www.aavso.org/epsilon-aurigae and http://www.citizensky.org/content/star-our-project). The Journal of the AAVSO, Volume 40, No. 2 (2012) was devoted to discussion of and research results from this event. See full Alert Notice for more details and observations.

  13. Measurement of bubble shape and size in bubbly flow structure for stagnant and pulsating liquid flow using an undivided electrochlorination cell and Telecentric Direct Image Method

    DEFF Research Database (Denmark)

    Andersen, Nikolaj; Stroe, Rodica-Elisabeta; Hedensted, Lau

    2016-01-01

    This study presents the measurement of shape and diameter of bubbles in different regions of the bubbly flow structure at the cathode for stagnant and pulsating liquid flow in a single undivided electrochlorination cell. The cell is filled with a dilute sodium chloride electrolyte solution...... is supported by an increase in fraction of total gas volume constituted by large bubbles. For pulsating liquid flow the mean bubble diameter is observed to remain constant around 35 μm when moving across the bubbly flow structure, which likewise is supported by the fraction of total gas volume investigations...

  14. Period Changes and Evolution in Pulsating Variable Stars

    Science.gov (United States)

    Neilson, H. R.; Percy, J. R.; Smith, H. A.

    2016-12-01

    We review ways in which observations of the changing periods of pulsating variable stars can be used to detect and directly measure their evolution. We briefly describe the two main techniques of analysis-(O-C) analysis and wavelet analysis - and results for pulsating variable star types which are reasonably periodic: type I and II Cepheids, RR Lyrae stars, beta Cephei stars, and Mira stars. We comment briefly on delta Scuti stars and pulsating white dwarfs. For some of these variable star types, observations agree approximately with the predictions of evolutionary models, but there still exist significant areas of disagreement that challenge future models of stellar evolution. There may be a need, for instance, to include processes such as rotation, mass loss, and magnetic fields. There may also be non-evolutionary processes which are contributing to the period changes.

  15. Heat transfer characteristics of impinging jet with pulsating frequency

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.I. [Chonbuk National University Graduate School, Chonju (Korea); Park, B.C.; Baek, B.J. [Chonbuk National University, Chonju (Korea)

    2000-11-01

    The method of impinging jet was applied lots of part in industrial field as a cooling of as gas turbine blade, a annealing of metal and plastic sheets, drying of textile, veneer paper, X-ray medical devices, laser weapons and electronic components. This study's main factor is reciprocating Jet impingement perpendicular to the heated Surface. We researched the effect of heat transfer and enhancement with pulsating air jet. The pulsating air jet has an improvement in pulsating Frequencies(f= 0.5, 1, 1.5, 3 Hz) and nozzle-to-plate distances(1/d= 2 {approx} 4, 6 {approx} 8, 4 {approx} 6, 8 {approx} 10). (author). 9 refs., 13 figs.

  16. Doubling the number of pulsating DB white dwarfs

    International Nuclear Information System (INIS)

    Nitta, Atsuko; Kleinman, S J; Krzenski, J; Kepler, S O; Metcalfe, T S; Mukadam, Anjum S; Mullally, F; Nather, R E; Winget, D E; Sullivan, D; Thompson, Susan E

    2009-01-01

    We are searching for new pulsating DB white dwarf stars (DBVs) based on the newly found white dwarf stars from the spectra obtained by the Sloan Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their better known cousins, DAVs or ZZ Ceti stars. Since the evolution of white dwarf stars is characterized by cooling, asteroseismological studies of DBVs give us opportunities to study white dwarf structure at a different evolutionary stage than the DAVs. The hottest DBVs are thought to have neutrino luminosities exceeding their photon luminosities (Winget et al. 2004), a quantity measurable through asteroseismology. Therefore, they can also be used to study neutrino physics in the stellar interior. At the time of the meeting, we reported on the nine new DBVs, doubling the number of previously known DBVs. Here we report the new nine pulsators' lightcurves and power spectra.

  17. On the pulsation modes and masses of RGB OSARGs

    Directory of Open Access Journals (Sweden)

    Saio H.

    2013-03-01

    Full Text Available OSARG (OGLE Small Amplitude Red Giants variables are RGB or AGB stars that show multi-periodic light variations with periods of about 10-100 days. Comparing linear nonadiabatic pulsation periods and period ratios with observed ones, we determined pulsation modes and masses of the RGB OSARG variables in the LMC. We found that pulsations of OSARGs involve radial 1st to 3rd overtones, p4 of l = 1, and p2 of l = 2 modes. The range of mass isfound to be 0.9-1.4M⊙ for RGB OSARGs and their mass-luminosity relation is logL/L⊙ = 0.79 M/M⊙ + 2.2.

  18. Articulated pipes conveying fluid pulsating with high frequency

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    1999-01-01

    Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hanging...... pipe position will lose stability if the mean flow speed exceeds a certain critical value. Adding a pulsating component to the fluid flow is shown to stabilize the hanging position for high values of the ratio between fluid and pipe-mass, and to marginally destabilize this position for low ratios....... An approximate nonlinear solution for small-amplitude flutter oscillations is obtained using a fifth-order multiple scales perturbation method, and large-amplitude oscillations are examined by numerical integration of the autonomous model equations, using a path-following algorithm. The pulsating fluid component...

  19. Flow rate pulsations of water with flicker power spectrum in an industrial sodium steam generator

    International Nuclear Information System (INIS)

    Reshetnikov, A.V.; Koverda, V.P.; Skokov, V.N.; Karpenko, A.I.; Govorov, P.P.; Bel'tyukov, A.I.

    2005-01-01

    The study on the spectral characteristics of the water flow pulsations in the evaporating modulus of the steam generator with sodium power unit BN-600 at the nominal capacity is carried out. It is shown that the outflow pulsations capacity spectrum changes inversely with the frequency (flicker pulsations). Origination of the identified high-energy low-frequency pulsations of the water outflow is related to the critical mode of the heat exchange, realized in the evaporation modulus [ru

  20. Estimation of friction loss under forced flow pulsations in a channel with discrete roughness elements

    Science.gov (United States)

    Davletshin, I. A.; Dushina, O. A.; Mikheev, N. I.; Kolchin, S. A.

    2017-11-01

    The pulsating flow in a circular channel with semicircular annular ribs as discrete roughness elements has been studied experimentally. Air flow under atmospheric conditions at the channel inlet has been considered. Steady and pulsating air flow has been studied under different frequencies and amplitudes of forced pulsations generated by periodic blockage of the channel cross section by a rotating flap. Flow resistance in pulsating regimes has been estimated from the average static pressure drop. The resistance values attained twice the steady flow ones.

  1. Arctic Black Carbon Loading and Profile Using the Single-Particle Soot Photometer (SP2) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, Arthur J [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-05-01

    One of the major issues confronting aerosol climate simulations of the Arctic and Antarctic cryospheres is the lack of detailed data on the vertical and spatial distribution of aerosols with which to test these models. This is due, in part, to the inherent difficulty of conducting such measurements in extreme environments. However given the pronounced sensitivity of the polar regions to radiative balance perturbations, it is incumbent upon our community to better understand and quantify these perturbations, and their unique feedbacks, so that robust model predictions of this region can be realized. One class of under-measured radiative forcing agents in the polar region is the absorbing aerosol—black carbon and brown carbon. Black carbon (BC; also referred to as light-absorbing carbon [LAC], refractory black carbon [rBC], and soot) is second only to CO2 as a positive forcing agent. Roughly 60% of BC emissions can be attributed to anthropogenic sources (fossil fuel combustion and open-pit cooking), with the remaining fraction being due to biomass burning. Brown carbon (BrC), a major component of biomass burning, collectively refers to non-BC carbonaceous aerosols that typically possess minimal light absorption at visible wavelengths but exhibit pronounced light absorption in the near-ultraviolet (UV) spectrum. Both species can be sourced locally or be remotely transported to the Arctic region and are expected to perturb the radiative balance. The work conducted in this field campaign addresses one of the more glaring deficiencies currently limiting improved quantification of the impact of BC radiative forcing in the cryosphere: the paucity of data on the vertical and spatial distributions of BC. By expanding the Gulfstream aircraft (G-1) payload for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility-sponsored ACME-V campaign to include the Single-Particle Soot Photometer (SP2)) and leveraging the ACME-V campaign

  2. γ DORADUS PULSATIONS IN THE ECLIPSING BINARY STAR KIC 6048106

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Woo, E-mail: jwlee@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 34113 (Korea, Republic of)

    2016-12-20

    We present the Kepler photometry of KIC 6048106, which is exhibiting the O’Connell effect and multiperiodic pulsations. Including a starspot on either of the components, light-curve synthesis indicates that this system is a semi-detached Algol with a mass ratio of 0.211, an orbital inclination of 73.°9, and a large temperature difference of 2534 K. To examine in detail both the spot variations and pulsations, we separately analyzed the Kepler time-series data at the interval of an orbital period in an iterative way. The results reveal that the variable asymmetries of the light maxima can be interpreted as the changes with time of a magnetic cool spot on the secondary component. Multiple frequency analyses were performed in the outside-eclipse light residuals after removal of the binarity effects from the observed Kepler data. We detected 30 frequencies with signal to noise amplitude ratios larger than 4.0, of which six ( f {sub 2}– f {sub 6} and f {sub 10}) can be identified as high-order (17 ≤  n  ≤ 25) low-degree ( ℓ  = 2) gravity-mode pulsations that were stable during the observing run of 200 days. In contrast, the other frequencies may be harmonic and combination terms. For the six frequencies, the pulsation periods and pulsation constants are in the ranges of 0.352–0.506 days and 0.232–0.333 days, respectively. These values and the position on the Hertzsprung–Russell diagram demonstrate that the primary star is a γ Dor variable. The evolutionary status and the pulsation nature of KIC 6048106 are discussed.

  3. Pulsation-based method for reduction of nitrogen oxides content in torch combustion products

    Science.gov (United States)

    Berg, I. A.; Porshnev, S. V.; Oshchepkova, V. Y.; Kit, M.

    2018-01-01

    Out of all ways to fuel bum the torch combustion systems is used most often. Even though the processes in the steam boiler are stochastic, the system can be controlled rather easily by changing the flowrate of the air pumped into it and – in case of balanced flue units – exhausters load. Advantages offered by torch-based combustion systems are offset by a disadvantage resulted in oxidation of nitrogen contained in the air. This paper provides rationale for an NOx content reduction method that employs pulsation mode of fuel combustion; it also describes combustion control and monitoring system employed for implementation of this method. Described methodology can be used not only for pulsation combustion studies but also for studies of torches formed by conventional burning systems. The outcome of the experimental study supports the assumption that it is possible to create conditions for NOx content reduction in flue gases by means of cycling the fuel supply on/off valve at the rate of 6 Hz.

  4. The Post-outburst Pulsations of GW Librae

    Science.gov (United States)

    Chote, P.; Mukadam, A. S.; Aungwerojwit, A.; Szkody, P.; Gänsicke, B. T.; Sullivan, D. J.; Poshyachinda, S.; Reichart, D. E.; Haislip, J. B.; Moore, J. P.

    2017-03-01

    We present new observations of GW Librae obtained between 2012 and 2016. GW Librae was the first accreting white dwarf to be discovered with non-radial pulsations, which were wiped out in 2007 when a dwarf nova outburst heated the surface of the WD outside the instability strip. In the years that followed, we have seen pulsations return with periods near 280 and 1200 seconds, but find that their periods and amplitudes vary on timescales longer than a few hours. Some of these changes are found to correlate with changes in the mysterious 2/3/4 hour modulation that has been seen both before and after the outburst.

  5. Transformerless photovoltaic inverters with leakage current and pulsating power elimination

    DEFF Research Database (Denmark)

    Tang, Yi; Yao, Wenli; Wang, H.

    2015-01-01

    This paper presents a transformerless inverter topology, which is capable of simultaneously solving leakage current and pulsating power issues in grid-connected photovoltaic (PV) systems. Without adding any additional components to the system, the leakage current caused by the PV-to-ground parasi......This paper presents a transformerless inverter topology, which is capable of simultaneously solving leakage current and pulsating power issues in grid-connected photovoltaic (PV) systems. Without adding any additional components to the system, the leakage current caused by the PV...

  6. Forced Transverse Vibration of a Closed Double Single-Walled Carbon Nanotube System Containing a Fluid with Effect of Compressive Axial Load

    Directory of Open Access Journals (Sweden)

    Mehrdad Nasirshoaibi

    2015-01-01

    Full Text Available Based on the Rayleigh beam theory, the forced transverse vibrations of a closed double single-walled carbon nanotube (SWCNT system containing a fluid with a Pasternak layer in-between are investigated. It is assumed that the two single-walled carbon nanotubes of the system are continuously joined by a Pasternak layer and both sides of SWCNTs containing a fluid are closed. The dynamic responses of the system caused by arbitrarily distributed continuous loads are obtained. The effect of compressive axial load on the forced vibrations of the double single-walled carbon nanotube system is discussed for one case of particular excitation loading. The properties of the forced transverse vibrations of the system are found to be significantly dependent on the compressive axial load. The steady-state vibration amplitudes of the SWCNT decrease with increasing of length of SWCNT. Vibrations caused by the harmonic exciting forces are discussed, and conditions of resonance and dynamic vibration absorption are formulated. The SWCNT-type dynamic absorber is a new concept of a dynamic vibration absorber (DVA, which can be applied to suppress excessive vibrations of corresponding SWCNT systems.

  7. Mismatch in mechanical and adhesive properties induces pulsating cancer cell migration in epithelial monolayer.

    Science.gov (United States)

    Lee, Meng-Horng; Wu, Pei-Hsun; Staunton, Jack Rory; Ros, Robert; Longmore, Gregory D; Wirtz, Denis

    2012-06-20

    The mechanical and adhesive properties of cancer cells significantly change during tumor progression. Here we assess the functional consequences of mismatched stiffness and adhesive properties between neighboring normal cells on cancer cell migration in an epithelial-like cell monolayer. Using an in vitro coculture system and live-cell imaging, we find that the speed of single, mechanically soft breast carcinoma cells is dramatically enhanced by surrounding stiff nontransformed cells compared with single cells or a monolayer of carcinoma cells. Soft tumor cells undergo a mode of pulsating migration that is distinct from conventional mesenchymal and amoeboid migration, whereby long-lived episodes of slow, random migration are interlaced with short-lived episodes of extremely fast, directed migration, whereas the surrounding stiff cells show little net migration. This bursty migration is induced by the intermittent, myosin II-mediated deformation of the soft nucleus of the cancer cell, which is induced by the transient crowding of the stiff nuclei of the surrounding nontransformed cells, whose movements depend directly on the cadherin-mediated mismatched adhesion between normal and cancer cells as well as α-catenin-based intercellular adhesion of the normal cells. These results suggest that a mechanical and adhesive mismatch between transformed and nontransformed cells in a cell monolayer can trigger enhanced pulsating migration. These results shed light on the role of stiff epithelial cells that neighbor individual cancer cells in early steps of cancer dissemination. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. Immediate loading versus immediate provisionalization of maxillary single-tooth replacements: a prospective randomized study with BioComp implants

    NARCIS (Netherlands)

    Lindeboom, Jerome A.; Frenken, Joost W.; Dubois, Leander; Frank, Michael; Abbink, Ingmar; Kroon, Frans H.

    2006-01-01

    PURPOSE: The aim of this prospective randomized study was to evaluate the clinical outcome of immediately loaded solid plasma sprayed (TPS) BioComp (BioComp Industries BV, Vught, The Netherlands) implants versus immediate provisionalized but non-loaded BioComp implants in the anterior and premolar

  9. High resolution in-situ x-ray diffraction of single carbon fibres at high loads and temperatures up to 1800oC

    International Nuclear Information System (INIS)

    Rennhofer, H.; Puchegger, S.; Pabisch, S.; Weinberger, M.; Peterlik, H.; Loidl, D.; Paris, O.

    2008-01-01

    Full text: A specially designed test equipment has been developed to perform in-situ x-ray diffraction experiments of single carbon fibres (HTA 5131, diameter 7 microns) with simultaneously applying high loads and temperatures up to 1800 o C. The test equipment operates in vacuum (pressure -4 mbar) and direct heating with cold grips is used. The structural change of the nm-wide crystallites, in particular with respect to their size, orientation and lattice parameters is followed in dependence on load and temperature. The results are compared to similar experiments on fiber-bundles, which were performed in the laboratory equipment. (author)

  10. Immediate Implant Placement and Loading of Single Implants in the Esthetic Zone: Clinical Outcome and Esthetic Evaluation in a Japanese Population.

    Science.gov (United States)

    Takeshita, Kenji; Vandeweghe, Stefan; Vervack, Valentin; Sumi, Takashi; De Bruyn, Hugo; Jimbo, Ryo

    2015-01-01

    This study evaluated the clinical outcomes of immediately loaded maxillary anterior single implants placed in fresh extraction sockets. A patient cohort that was treated 1.5 years earlier was recalled, and 18 patients (6 men, 12 women) with 21 implants were included. Clinical photographs and periapical radiographs were taken at follow-up and baseline to determine the bone loss and change in esthetics. No marginal bone loss was detected at follow-up (mean bone level ± standard deviation = 0.32 ± 0.82 mm). Immediate implant placement and loading resulted in predictable clinical and esthetic outcomes, with soft and hard tissue levels remaining stable over time.

  11. The occurrence of binary evolution pulsators in classical instability strip of RR Lyrae and Cepheid variables

    Science.gov (United States)

    Karczmarek, P.; Wiktorowicz, G.; Iłkiewicz, K.; Smolec, R.; Stępień, K.; Pietrzyński, G.; Gieren, W.; Belczynski, K.

    2017-04-01

    Single star evolution does not allow extremely low-mass stars to cross the classical instability strip (IS) during the Hubble time. However, within binary evolution framework low-mass stars can appear inside the IS once the mass transfer (MT) is taken into account. Triggered by a discovery of low-mass (0.26 M⊙) RR Lyrae-like variable in a binary system, OGLE-BLG-RRLYR-02792, we investigate the occurrence of similar binary components in the IS, which set up a new class of low-mass pulsators. They are referred to as binary evolution pulsators (BEPs) to underline the interaction between components, which is crucial for substantial mass-loss prior to the IS entrance. We simulate a population of 500 000 metal-rich binaries and report that 28 143 components of binary systems experience severe MT (losing up to 90 per cent of mass), followed by at least one IS crossing in luminosity range of RR Lyrae (RRL) or Cepheid variables. A half of these systems enter the IS before the age of 4 Gyr. BEPs display a variety of physical and orbital parameters, with the most important being the BEP mass in range 0.2-0.8 M⊙, and the orbital period in range 10-2 500 d. Based on the light curve only, BEPs can be misclassified as genuine classical pulsators, and as such they would contaminate genuine RRL and classical Cepheid variables at levels of 0.8 and 5 per cent, respectively. We state that the majority of BEPs will remain undetected and we discuss relevant detection limitations.

  12. Early survival of single-tooth implants in the esthetic zone may be predictable despite timing of implant placement or loading.

    Science.gov (United States)

    Knoernschild, Kent L

    2012-09-01

    The authors used MEDLINE, EMBASE, and CENTRAL (Cochrane Central Register of Controlled Trials) databases to locate studies for this systematic review (SR). For studies to be eligible for this SR, all had to evaluate single-implant restorations with a follow-up of at least 1 year after implant loading. A total of 19 prospective studies met inclusion and exclusion criteria. Fifteen studies provided implant survival data (499 patient/509 implants), whereas 5 studies provided radiographic marginal bone height data (52 patients/52 implants). The analysis included studies with patients with single anterior or premolar, maxillary or mandibular edentulous sites bounded by anterior and posterior neighboring teeth. Meta-analyses of prospective trials (randomized-controlled trials, clinical trials, cohort studies, case series) reported loaded implant survival with one-year or more than one-year follow-up. Meta-analysis of prospective trials reporting marginal bone loss with one-year follow-up was also reported. The key interventions were the timing of implant placement following extraction and the timing of implant loading after implant placement. Comparisons following greater than one-year follow-up were made between implants with immediate placement with immediate loading, immediate/early placement with conventional loading, conventional placement with immediate/early loading, or conventional placement with conventional loading. The main outcome was implant survival. Radiographically determined peri-implant bone level change was also reported. Meta-analyses were completed using studies that reported one-year implant survival data (15 studies) and more than one-year implant survival data (11 studies). One-year marginal bone level data were analyzed for implants treated conventionally (5 studies). For survival and marginal bone levels, weighted rates and random effects models were used to calculate overall effects of the included studies. For greater than one-year follow

  13. Pulsating aurora from electron scattering by chorus waves

    Science.gov (United States)

    Kasahara, S.; Miyoshi, Y.; Yokota, S.; Mitani, T.; Kasahara, Y.; Matsuda, S.; Kumamoto, A.; Matsuoka, A.; Kazama, Y.; Frey, H. U.; Angelopoulos, V.; Kurita, S.; Keika, K.; Seki, K.; Shinohara, I.

    2018-02-01

    Auroral substorms, dynamic phenomena that occur in the upper atmosphere at night, are caused by global reconfiguration of the magnetosphere, which releases stored solar wind energy. These storms are characterized by auroral brightening from dusk to midnight, followed by violent motions of distinct auroral arcs that suddenly break up, and the subsequent emergence of diffuse, pulsating auroral patches at dawn. Pulsating aurorae, which are quasiperiodic, blinking patches of light tens to hundreds of kilometres across, appear at altitudes of about 100 kilometres in the high-latitude regions of both hemispheres, and multiple patches often cover the entire sky. This auroral pulsation, with periods of several to tens of seconds, is generated by the intermittent precipitation of energetic electrons (several to tens of kiloelectronvolts) arriving from the magnetosphere and colliding with the atoms and molecules of the upper atmosphere. A possible cause of this precipitation is the interaction between magnetospheric electrons and electromagnetic waves called whistler-mode chorus waves. However, no direct observational evidence of this interaction has been obtained so far. Here we report that energetic electrons are scattered by chorus waves, resulting in their precipitation. Our observations were made in March 2017 with a magnetospheric spacecraft equipped with a high-angular-resolution electron sensor and electromagnetic field instruments. The measured quasiperiodic precipitating electron flux was sufficiently intense to generate a pulsating aurora, which was indeed simultaneously observed by a ground auroral imager.

  14. Pc1 with a broad frequency spectrum - "Goose pulsations"

    Czech Academy of Sciences Publication Activity Database

    Feygin, F. Z.; Prikner, Karel; Kangas, J.

    2009-01-01

    Roč. 53, č. 4 (2009), s. 519-536 ISSN 0039-3169 Institutional research plan: CEZ:AV0Z30120515 Keywords : geomagnetic pulsations * nonlinear particle-wave interaction * Pc1 wave packets * ionospheric Alfvén resonator (IAR) Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.000, year: 2009

  15. Large-scale coordinated observations of Pc5 pulsation events

    Directory of Open Access Journals (Sweden)

    Z. Mtumela

    2016-09-01

    Full Text Available HF (high-frequency radars belonging to SuperDARN (Super Dual Auroral Radar Network receive backscatter over substantial fields of view which, when combined, allow for simultaneous returns over extensive regions of the polar caps and midlatitudes. This makes them ideal instruments for the observation of pulsations in the Pc5 (1–5 mHz frequency band. Relatively few pulsation events observed by multiple radars have been reported in the literature. Here we describe observations of three such events which extend over more than 120° of magnetic longitude in the Northern Hemisphere and one of which is also detected in the Southern Hemisphere. All three events show characteristics of field line resonances. In one case the pulsation has also been observed by magnetometers under or near the radar fields of view. The extensive longitudinal coverage allows accurate determination of azimuthal wave numbers. These are at the upper end of the lower values associated with external sources such as those in the solar wind. Such sources imply antisunward flow. However, the azimuthal wave number is negative, implying westward propagation at magnetic local times on both sides of noon, as would be expected from drift–bounce resonance with positive particles. Quiet conditions and a very low ring current during the events argue against this. The identification of the source of pulsations from a number of different mechanisms remains a problem of interest.

  16. Pulsation and precession of the resonant swinging spring

    Science.gov (United States)

    Lynch, Peter; Houghton, Conor

    2004-03-01

    When the frequencies of the elastic and pendular oscillations of an elastic pendulum or swinging spring are in the ratio 2:1, there is a regular exchange of energy between the two modes of oscillation. We refer to this phenomenon as pulsation. Between the horizontal excursions, or pulses, the spring undergoes a change of azimuth which we call the precession angle. The pulsation and stepwise precession are the characteristic features of the dynamics of the swinging spring. The modulation equations for the small-amplitude resonant motion of the system are the well-known three-wave equations. We use Hamiltonian reduction to determine a complete analytical solution. The amplitudes and phases are expressed in terms of both Weierstrass and Jacobi elliptic functions. The strength of the pulsation may be computed from the invariants of the equations. Several analytical formulas are found for the precession angle. We deduce simplified approximate expressions, in terms of elementary functions, for the pulsation amplitude and precession angle and demonstrate their high accuracy by numerical experiments. Thus, for given initial conditions, we can describe the envelope dynamics without solving the equations. Conversely, given the parameters which determine the envelope, we can specify initial conditions which, to a high level of accuracy, yield this envelope.

  17. Ground pulsation magnetometer observations conjugated with relativistic electron precipitation

    Science.gov (United States)

    Yahnin, A. G.; Yahnina, T. A.; Raita, T.; Manninen, J.

    2017-09-01

    In this report, we investigate the role of electromagnetic ion cyclotron (EMIC) waves in production of relativistic electron precipitation (REP). Over a thousand REP events were detected from four NOAA Polar-orbiting Operational Environmental Satellites in July-December 2005. Of these, a total of 112 events were conjugated with a ground-based network of six Finnish induction coil magnetometers and one in Lovozero observatory at Kola Peninsula, Russia. The observation of geomagnetic pulsations during the conjugated events showed that about one third of them were accompanied by pulsations in the Pc1 range, which are the signature of EMIC waves. In fact, the sources of some of these EMIC waves were well outside the location of the REP event. This means that in such cases the REP events were not originated from scattering by EMIC waves. Finally, it is concluded that for this limited set of conjugated events only a quarter might be related to scattering by EMIC waves. The majority of the events are not correlated with EMIC wave signatures in ground-based observations; they were associated with either no pulsations or noise-like pulsations PiB and PiC.

  18. Pulsational instabilities in hot pre-horizontal branch stars

    Directory of Open Access Journals (Sweden)

    Battich Tiara

    2017-01-01

    Full Text Available The ϵ mechanism is a self-excitation mechanism of pulsations which acts on the regions where nuclear burning takes place. It has been shown that the ϵ mechanism can excite pulsations in models of hot helium-core flash, and that the pulsations of LS IV-14· 116, a He-enriched hot subdwarf star, could be explained that way. We aim to study the ϵmechanism effects on models of hot pre-horizontal branch stars and determine, if possible, a domain of instability in the log g — log Teff plane. We compute non-adiabatic non-radial pulsations on such stellar models, adopting different values of initial chemical abundances and mass of the hydrogen envelope at the time of the main helium flash. We find an instability domain of long-period (400 s ≲ P ≲ 2500 s g-modes for models with 22000K ≲ Teff ≲ 50000K and 4.67 ≲ log g ≲ 6.15.

  19. A test of Pulsation Theory in Hot B Subdwarfs

    Science.gov (United States)

    Fontaine, Gilles

    There are currently of the order of 15 hot B subdwarf (sdB) stars which are known to exhibit low-amplitude (a few to tens of millimag), short-period (100-500 s), multiperiodic luminosity variations. These pulsations are thought to be driven by an opacity bump linked to the presence of a local enhancement of the iron abundance in the envelopes of sdB stars. Such an enhancement results quite naturally from the diffusive equilibrium between gravitational settling and radiative support in the stellar envelope. Nevertheless, surveys for pulsating sdB stars show that, in several instances, variable and non-variable objects with similar effective temperatures and gravities may coexist in the HR diagram. This result suggests that an additional parameter, perhaps a weak stellar wind, might affect the extent of the iron reservoir and thus the ability of the latter to drive pulsations in sdB stars. Fortunately, it is expected that such a wind might also leave its mark on the photospheric heavy element abundance patterns. The intended FUSE observations will i) permit a direct comparison of the heavy element abundance patterns in variable and nonvariable stars of similar atmospheric parameters; ii) provide a consistency check with our wind models; and iii) provide a test of the currently-favored explanation for the driving of the observed pulsations.

  20. A Test of Pulsation Theory in Hot B Subdwarfs (bis)

    Science.gov (United States)

    Fontaine, G.

    There are currently 33 hot B subdwarf (sdB) stars which are known to exhibit low-amplitude (a few to tens of mmag), short-period (100-500 s), multiperiodic luminosity variations caused by acoustic mode instabilities. These pulsations are thought to be driven by an opacity bump linked to the presence of a local enhancement of the iron and other iron-peak elements) abundance in the envelopes of sdB stars. Such an enhancement results quite naturally from the diffusive equilibrium between gravitational settling and radiative support in the stellar envelope. Nevertheless, surveys for pulsating sdB stars show that variable and nonvariable objects with similar effective temperatures and gravities coexist in the log g-Teff diagram. This puzzling result suggests that an additional parameter, perhaps a weak stellar wind, might affect the extent of the iron reservoir and thus the ability of the latter to drive pulsations in sdB stars. Fortunately, it is expected that such a wind might also leave its mark on the photospheric heavy element abundance patterns. The intended FUSE observations will 1) permit a direct comparison of the heavy element abundance patterns in variable and nonvariable stars of similar atmospheric parameters, 2) provide a consistency check with our wind models, and 3) provide a test of the currently-favored explanation for the driving of the observed pulsations.

  1. Massive B-type pulsators in low-metallicity environments

    Science.gov (United States)

    Karoff, C.; Arentoft, T.; Glowienka, L.; Coutures, C.; Nielsen, T. B.; Dogan, G.; Grundahl, F.; Kjeldsen, H.

    2009-07-01

    Massive B-type pulsators such as β Cep and slowly pulsating B (SPB) stars pulsate due to layers of increased opacity caused by partial ionization. The increased opacity blocks the energy flux to the surface of the stars which causes the layers to rise and the opacity to drop. This cyclical behavior makes the star act as a heat engine and the star will thus pulsate. For β Cep and SPB stars the increased opacity is believed to be caused by partial ionization of iron and these stars should therefore contain non-insignificant quantities of the metal. A good test of this theory is to search for β Cep and SPB stars in low-metallicity environments. If no stars are found the theory is supported, but, on the other hand, if a substantial number of β Cep and SPB stars are found in these environments then the theory is not supported and a %solutions solution is needed. With a growing number of identified β Cep and SPB stars in the low-metallicity Magellanic Clouds we seem to be left with the second case. We will in this context discuss recent findings of β Cep and SPB stars in the Magellanic Clouds and some possible solutions to the discrepancy between these observations and the theory. We also describe an ambitious project that we have initiated on the Small Magellanic Cloud open cluster NGC 371 which will help to evaluate these solutions.

  2. Shear transfer across a single crack in reinforced concrete under sustained loading. Part III : Analysis of experiments

    NARCIS (Netherlands)

    Frénay, J.W.

    1985-01-01

    The results of experimental investigations on internally reinforced "pushoff" test specimens, each formed with one central crack and subjected to a constant external shear loading, were analysed. The crack width and the parallel displacement were measured periodically. The experimental variables

  3. Lower limb muscle pre-motor time measures during a choice reaction task associate with knee abduction loads during dynamic single leg landings.

    Science.gov (United States)

    McLean, Scott G; Borotikar, Bhushan; Lucey, Sarah M

    2010-07-01

    Female neuromuscular control during dynamic landings is considered central to their increased ACL injury risk relative to males. There is limited insight, however, into the neuromuscular parameters governing this risk, which may hinder prevention success. This study targeted a new screenable and potentially trainable neuromuscular risk factor. Specifically, we examined whether lower limb muscle pre-motor times, being the time between stimulus presentation and initiation of the muscle EMG burst, elicited during a simple choice reaction task correlated with knee abduction loads during separate single leg landings. Twenty female NCAA athletes had muscle (n=8) pre-motor time and knee biomechanics data recorded bilaterally during a choice reaction task. Knee biomechanics were also quantified during anticipated and unanticipated single (dominant and non-dominant) leg landings. Mean peak knee abduction loads during landings were submitted to a two-way ANOVA to test for limb and decision effects. Individual regression coefficients were initially computed between-limb-based muscle pre-motor times and peak abduction moments elicited during both the choice reaction and landing tasks. Limb-based linear stepwise regression coefficients were also computed between muscle PMT's demonstrating significant (Pmuscle pre-motor times during a specific choice reaction task are associated with peak knee abduction loads during separate single leg landings. These muscles appear critical in stabilizing the knee against the extreme dynamic load states associated with such tasks. Targeted screening and training of supraspinal processes governing these muscle pre-motor times may ultimately enable external knee loads associated with landings to be more effectively countered by the overarching neuromuscular strategy. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  4. Colors of the pulsations and flickering of Sy Cancri during outburst

    International Nuclear Information System (INIS)

    Middleditch, J.; Cordova, F.A.

    1982-01-01

    The spectra of the short period (approx.30 s) oscillations and flickering of the dwarf nova Sy Cnc have been determined by simultaneous measuring the optical flux in three broad, contiguous spectral bands during an optical outburst of the star. The spectrum of the oscillation rises too rapidly toward short wavelengths to be consistent with any simple thermal model. The colors of the flickering are even more extreme (i.e., more ultraviolet) than those of the pulsations. No timing differences were detected to a fraction of a second between the ultraviolet (U), cyan (B+V, or C) and red (R, to 9000 A) bands of the pulsations; thus, the optical oscillations appear to arise from a single physical location in the binary system. Without a detailed study of a more complicated class of models, which may include recombination radiation from H I, He I, and He II in addition to a thermal model, it is impossible to assign a temperature to the oscillations and thereby determine whether they are produced directly on the white dwarf or in the accretion disk

  5. Correlations between fracture load of zirconia implant supported single crowns and mechanical properties of restorative material and cement.

    Science.gov (United States)

    Rohr, Nadja; Märtin, Sabrina; Fischer, Jens

    2017-11-23

    Zirconia implants that were restored with veneered zirconia displayed severe chipping rates of the restorations in clinical studies. Purpose of this study was to evaluate the fracture load of different zirconia implant supported monolithic crown materials (zirconia, alumina, lithium disilicate, feldspar ceramic and polymer-infiltrated ceramic) cemented with various cements (Harvard LuteCem SE, Harvard Implant Semi-permanent, Multilink Automix, VITA Adiva F-Cem). Flexural strength and fracture toughness of crown materials and compressive strength of the cements were measured. Fracture load values of crowns fabricated from lithium disilicate, feldspar ceramic and polymer-infiltrated ceramic were increased when cement with high compressive strength was used. Fracture loads for zirconia and alumina crowns were not influenced by the cement. Flexural strength and fracture toughness of the ceramics correlated linearly with the respective fracture load when using adhesive cement with high compressive strength. To achieve sufficient fracture load values, cementation with adhesive cement is essential for feldspar and polymer-infiltrated ceramic.

  6. The Effect of Compressive Cyclic Loading on the Retention of Cast Single Crowns Cemented to Implant Abutments.

    Science.gov (United States)

    Alvarez-Arenal, Angel; Gonzalez-Gonzalez, Ignacio; Pinés-Hueso, Javier; deLlanos-Lanchares, Hector; del Rio Highsmith, Jaime

    2016-01-01

    The aim of this study was to evaluate and compare the retention strength of three cements commonly used in implant-supported prostheses before and after compressive cyclic loading. The working model consisted of five solid abutments, 7 mm in height and with a 6-degree taper, screw retained to five implant analogs secured in a rectangular block of self-curing acrylic. On the abutments, 30 metal Cr-Ni alloy copings were cemented using three luting agents: glass ionomer, resin urethane-based, and compomer cement (n = 10). Two tensile tests were conducted with a universal testing machine, before and after 100,000 cycles of 100 N and 0.72 Hz compressive cyclic loading in a humid environment. Before applying the compressive load, the retention strength of the resin urethane-based cement was slightly higher than that of the compomer cement and 75% greater than the glass-ionomer cement. After compressive loading, the resin urethane-based cement showed the highest percentage of loss of retention (64.45%, compared with 50% for glass-ionomer and compomer cement). However, the glass-ionomer cement showed the lowest mean retentive strength with 50.35 N as opposed to 75.12 N for the compomer cement and 71.25 N for the resin urethane-based. Compressive cyclic loading significantly influences the retention strength of the luting agents tested. All three cements may favor the retrievability of the crowns.

  7. Immediate non-occlusal loading of immediate post-extractive versus delayed placement of single implants in preserved sockets of the anterior maxilla: 1-year post-loading outcome of a randomised controlled trial.

    Science.gov (United States)

    Felice, Pietro; Pistilli, Roberto; Barausse, Carlo; Trullenque-Eriksson, Anna; Esposito, Marco

    2015-01-01

    To compare the effectiveness of immediate post-extractive single implants with delayed implants placed in preserved sockets after 4 months of healing. Implants that achieved an insertion torque of at least 35 Ncm were immediately non-occlusally loaded. Just after tooth extraction, and in the presence of less than 4 mm of vertical loss of the buccal bone in relation to the palatal wall, 50 patients requiring a single immediate post-extractive implant in the maxilla from second to second premolar were randomly allocated for either immediate implant placement (immediate group; 25 patients) or for socket preservation using an algae-derived (phycogenic) bone substitute, covered by a resorbable collagen barrier (delayed group; 25 patients), according to a parallel group design in one centre. Bone-to-implant gaps were filled with an algae-derived bone substitute. Four months after socket preservation, delayed implants were placed. Implants inserted with an insertion torque of at least 35 Ncm were immediately loaded with non-occluding provisional single crowns, then replaced, after 4 months, by definitive crowns. Patients were followed up to 1 year after loading. Outcome measures were implant failures, complications, aesthetics assessed using the pink esthetic score (PES), peri-implant marginal bone level changes and patient satisfaction, recorded by blinded assessors. Nine (36%) implants were not immediately loaded in the immediate group versus 19 (76%) implants in the delayed placement group, because an insertion torque superior to 35 Ncm could not be obtained, the difference being statistically significant (difference = - 0.40, 95% CI: -0.652 to -0.148, P = 0.010). Two patients dropped out 4 months after loading in the delayed group versus none in the immediate group. Two implants failed in the immediate group (8%) versus none in the delayed group, with the difference showing no statistical significance (considering 25 and 23 patients, the difference in proportions was

  8. Alveolar Bone Resorption Evaluation Around Single-piece Designed Bicortical Implants, Using Immediate Loading Protocol, Based on Orthopantomographs

    Directory of Open Access Journals (Sweden)

    Száva Dániel-Tamás

    2017-12-01

    Full Text Available Background: Inserting dental implants in severely atrophied jawbones is a great challenge for the dental practitioner. There are an increasing number of patients who choose dental implantanchored prosthetic restorations despite compromised bone quality and quantity. There have been numerous attempts in adapting implant design for the atrophic crestal bone. One-piece, needle-type basal implant design is a typical design for these cases. These implants are inserted in the remaining compact bone located in the basal aspect of the jawbones. If high primary stability is achieved, these implants are used for immediate loading protocol. From many points of view, this technique is based on contradictory principles compared to classic implant surgery and loading protocols. The aim of this study was to investigate the long-term success of basal one-piece short-diameter dental implants used for immediate loading protocol.

  9. Inlay-retained cantilever fixed dental prostheses to substitute a single premolar: impact of zirconia framework design after dynamic loading.

    Science.gov (United States)

    Shahin, Ramez; Tannous, Fahed; Kern, Matthias

    2014-08-01

    The purpose of this in-vitro study was to evaluate the influence of the framework design on the durability of inlay-retained cantilever fixed dental prostheses (IR-FDPs), made from zirconia ceramic, after artificial ageing. Forty-eight caries-free human premolars were prepared as abutments for all-ceramic cantilevered IR-FDPs using six framework designs: occlusal-distal (OD) inlay, OD inlay with an oral retainer wing, OD inlay with two retainer wings, mesial-occlusal-distal (MOD) inlay, MOD inlay with an oral retainer ring, and veneer partial coping with a distal box (VB). Zirconia IR-FDPs were fabricated via computer-aided design/computer-aided manufacturing (CAD/CAM) technology. The bonding surfaces were air-abraded (50 μm alumina/0.1 MPa), and the frameworks were bonded with adhesive resin cement. Specimens were stored for 150 d in a 37°C water bath during which they were thermocycled between 5 and 55°C for 37,500 cycles; thereafter, they were exposed to 600,000 cycles of dynamic loading with a 5-kg load in a chewing simulator. All surviving specimens were loaded onto the pontic and tested until failure using a universal testing machine. The mean failure load of the groups ranged from 260.8 to 746.7 N. Statistical analysis showed that both MOD groups exhibited significantly higher failure loads compared with the other groups (i.e. the three OD groups and the VB group) and that there was no significant difference in the failure load among the OD groups and the VB group. In conclusion, zirconia IR-FDPs with a modified design exhibited promising failure modes. © 2014 Eur J Oral Sci.

  10. Immediate non-occlusal loading of immediate post-extractive versus delayed placement of single implants in preserved sockets of the anterior maxilla: 4-month post-loading results from a pragmatic multicentre randomised controlled trial.

    Science.gov (United States)

    Felice, Pietro; Soardi, Elisa; Piattelli, Maurizio; Pistilli, Roberto; Jacotti, Michele; Esposito, Marco

    2011-01-01

    To compare the effectiveness of immediate post-extractive single implants with delayed implants placed in preserved sockets after 4 months of healing. Implants that achieved an insertion torque of at least 35 Ncm were immediately non-occlusally loaded. Just after tooth extraction and in the presence of a loss of the buccal plate bone less than 4 mm, compared to the palatal wall, 106 patients requiring a single immediate postextractive implant in the maxilla from second premolar to second premolar were randomly allocated to immediate implant placement (immediate group; 54 patients) or to socket preservation using anorganic bovine bone covered by a resorbable collagen barrier (delayed group; 52 patients) according to a parallel group design at three different centres. Bone-to-implant gaps were to be filled with anorganic bovine bone, however this was not done in 17 patients (corresponding to 40% of those who should have been grafted). Four months after socket preservation, delayed implants were placed. Implants placed with an insertion torque >35 Ncm were immediately loaded with non-occluding provisional single crowns, replaced, after 4 months, by definitive crowns. Outcome measures were implant failures, complications, aesthetics assessed using the pink esthetic score (PES), and patient satisfaction, recorded by blinded assessors. All patients were followed up to 4 months after loading. Nineteen (35%) implants were not immediately loaded in the immediate group versus 39 (75%) implants in the delayed placement group because an insertion torque >35 Ncm could not be obtained. No patient dropped out. Two implants failed in the immediate group (4%) versus none in the delayed group. More minor complications occurred in the immediate group (8) than the in the delayed group (1) and this was statistically significant (P = 0.032). At delivery of definitive crowns, 4 months after loading, aesthetics were scored as 12.8 and 12.6 in the immediate and delayed groups, respectively

  11. Pulsating combustion - Combustion characteristics and reduction of emissions

    Energy Technology Data Exchange (ETDEWEB)

    Lindholm, Annika

    1999-11-01

    In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy. Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well founded theory of the phenomenon. Research concerning control over the combustion process is essential for developing high efficiency pulse combustors with low emissions. Natural gas fired Helmholtz type pulse combustors have been the experimental objects of this study. In order to investigate the interaction between the fluid dynamics and the chemistry in pulse combustors, laser based measuring techniques as well as other conventional measuring techniques have been used. The experimental results shows the possibilities to control the combustion characteristics of pulsating combustion. It is shown that the time scales in the large vortices created at the inlet to the combustion chamber are very important for the operation of the pulse combustor. By increasing/decreasing the time scale for the large scale mixing the timing of the heat release is changed and the operating characteristics of the pulse combustor changes. Three different means for NO{sub x} reduction in Helmholtz type pulse combustors have been investigated. These include exhaust gas recirculation, alteration of air/fuel ratio and changed inlet geometry in the combustion chamber. All used methods achieved less than 10 ppm NO{sub x} emitted (referred to stoichiometric

  12. Ionospheric electron heating associated with pulsating auroras: A Swarm survey and model simulation

    Science.gov (United States)

    Liang, Jun; Yang, B.; Donovan, E.; Burchill, J.; Knudsen, D.

    2017-08-01

    In this paper we report a study on the plasma signatures (electron temperature, plasma density, and field-aligned current) of patchy pulsating auroras in the upper F region ionosphere using Swarm satellite data. Via a survey of 38 patch crossing events, we repeatedly identify a strong electron temperature enhancement associated with the pulsating aurora. On average, the electron temperature at Swarm satellite altitudes ( 460 km) increases from 2200 K at subauroral latitudes to a peak of 3000 K within the pulsating auroral patch. This indicates that pulsating auroras may act as an important heating source for the nightside ionosphere. On the other hand, no well-defined trend of plasma density variations associated with pulsating auroras is identified at Swarm altitudes. The field-aligned currents within the pulsating aurora patch are mostly upward, with mean magnitudes on order of 1 μA/m2. We then perform a numerical simulation to explore the potential mechanisms underlying the strong electron heating associated with the pulsating aurora. Via simulations we find that to account for the realistic electron temperature observation in a major portion of our events, pulsating auroras are likely accompanied by substantial magnetospheric heat fluxes around the order of 1010 eV/cm2. We propose that such magnetospheric heat fluxes may be pertinent to one long-hypothesized feature of pulsating auroras, namely, the coexistence of an enhanced low-energy plasma population in magnetic flux tubes threading the pulsating aurora, in addition to the energetic electron precipitation. Via a Swarm survey we repeatedly find a strong electron temperature enhancement associated with the pulsating aurora The field-aligned currents within pulsating auroras are moderately upward, with mean magnitudes on the order of 1e-6 A/m2 To explain the observed electron heating, pulsating auroras are likely accompanied by magnetospheric heat fluxes around 1E+10 eV/cm2/s.

  13. First Kepler results on compact pulsators – VIII. Mode identifications via period spacings in g-mode pulsating subdwarf B stars

    DEFF Research Database (Denmark)

    Reed, M.D.; Baran, A.; Quint, A.C.

    2011-01-01

    consecutive overtones making period spacings easy to detect, six others have fewer consecutive overtones but period spacings are readily detected, and two stars show marginal indications of equal-period spacings. We also examine a g-mode sdB pulsator observed by CoRoT with a rich pulsation spectrum, and our...

  14. Triple-Loaded Single-Row Versus Suture-Bridge Double-Row Rotator Cuff Tendon Repair With Platelet-Rich Plasma Fibrin Membrane: A Randomized Controlled Trial.

    Science.gov (United States)

    Barber, F Alan

    2016-05-01

    To compare the structural healing and clinical outcomes of triple-loaded single-row with suture-bridging double-row repairs of full-thickness rotator cuff tendons when both repair constructs are augmented with platelet-rich plasma fibrin membrane. A prospective, randomized, consecutive series of patients diagnosed with full-thickness rotator cuff tears no greater than 3 cm in anteroposterior length were treated with a triple-loaded single-row (20) or suture-bridging double-row (20) repair augmented with platelet-rich plasma fibrin membrane. The primary outcome measure was cuff integrity by magnetic resonance imaging (MRI) at 12 months postoperatively. Secondary clinical outcome measures were American Shoulder and Elbow Surgeons, Rowe, Simple Shoulder Test, Constant, and Single Assessment Numeric Evaluation scores. The mean MRI interval was 12.6 months (range, 12-17 months). A total of 3 of 20 single-row repairs and 3 of 20 double-row repairs (15%) had tears at follow-up MRI. The single-row group had re-tears in 1 single tendon repair and 2 double tendon repairs. All 3 tears failed at the original attachment site (Cho type 1). In the double-row group, re-tears were found in 3 double tendon repairs. All 3 tears failed medial to the medial row near the musculotendinous junction (Cho type 2). All clinical outcome measures were significantly improved from the preoperative level (P plasma fibrin membrane. No difference could be demonstrated between these repairs on clinical outcome scores. I, Prospective randomized study. Copyright © 2016 Arthroscopy Association of North America. All rights reserved.

  15. Changing distribution and geometry of S′ in Al–Cu–Mg single crystals during stress aging by controlling the loading orientation

    International Nuclear Information System (INIS)

    Chen, Jiqiang; Chen, Zhiguo; Guo, Xiaobin; Deng, Yunlai

    2016-01-01

    The precipitation behavior of S′ phase in Al–Cu–Mg single crystals during stress-free and stress aging was investigated by transmission electron microscopy (TEM). Different compressive stress magnitudes and loading orientations were applied to determine their effects on the precipitation of S′ in Al–Cu–Mg alloy during stress aging. The results indicate that a noticeable preferential orientation of S′ is generated in the sample under applied compressive stress of 33 MPa loading along close to [001] Al , whilst no obviously preferential orientation of S′ can be observed in the sample loaded along close to [101] Al under the same applied stress or even larger applied stress. The precipitation distribution of S′ phase during stress aging can be changed by the loading orientation of the applied stress. Moreover, compressive stress aging may lead to S′ phase shorter in length, and the length of S′ phase shows a decreasing tendency with increasing applied stress, which are associated with the positive misfit between S′ and Al matrix.

  16. An analysis of the static load test on single square pile of 40x40 cm2, using finite element method in Rusunawa project, Jatinegara, Jakarta

    Science.gov (United States)

    Harasid, Harun; Roesyanto; Iskandar, Rudi; Silalahi, Sofyan A.

    2018-03-01

    Piling Foundation is one of the foundations which is used to penetrate its load through soil layer. The power carried by the piling is obtained from the end bearing capacity, that is, the compressive end piling and friction bearing capacity obtained from friction bearing and adhesive capacity between the piling and the soil around it. The investigation on the Standard Penetration Test is aimed to get the description of soil layer, based on the type and color of soil through visual observation, and soil characteristics. SPT data can be used to calculate bearing capacity. Besides investigating the SPT, this study is also been equipped by taking the samples in laboratory and loading test on the piling and Ducth Cone Penetrometer (DCP) data to confirm its bearing capacity. This study analyzed bearing capacity and settlement in the square pile of 40X40 cm in diameter in a single pile or grouped, using an empirical method, AllPile program, Plaxis program, and comparing the result with interpreting its loading test in the foundation of Rusunawa project, Jatinegara, Jakarta. The analysis was been done by using the data on soil investigation and laboratory by comparing them with Mohr-Coulomb soil model. Ultimate bearing capacity from the SPT data in the piling of 15.4 meters was 189.81 tons and the parameter of soil shear strength was 198.67 tons. The sander point, based on Aoki and De Alencar bearing capacity was 276.241 tons and based on Mayerhoff it was 305.49 tons. Based on the loading test of bearing capacity, unlimited bearing capacity for the three methods was Davisson (260 tons), Mazurkiewich (270 tons), and Chin (250 tons). The efficiency of grouped piles according to Converse-Library Equation method = 0.73, according to Los Angeles Group Action Equation method = 0.59, and according to Sheila-Keeny method = 0.94. Bearing capacity based on piling strength was 221.76 tons, bearing capacity based on calendaring data was 201.71 tons, and lateral bearing capacity of a

  17. The First Six Outbursting Cool DA White Dwarf Pulsators

    Science.gov (United States)

    Bell, K. J.; Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Gentile Fusillo, N. P.; Raddi, R.; Gänsicke, B. T.

    2017-03-01

    Extensive observations from the Kepler spacecraft have recently revealed a new outburst phenomenon operating in cool pulsating DA (hydrogen atmosphere) white dwarfs (DAVs). With the introduction of two new outbursting DAVs from K2 Fields 7 (EPIC 229228364) and 8 (EPIC 220453225) in these proceedings, we presently know of six total members of this class of object. We present the observational commonalities of the outbursting DAVs: (1) outbursts that increase the mean stellar flux by up to ≍15%, last many hours, and recur irregularly on timescales of days; (2) effective temperatures that locate them near the cool edge of the DAV instability strip; and (3) rich pulsation spectra with modes that are observed to wander in amplitude/frequency.

  18. Experimental investigation on a pulsating heat pipe with hydrogen

    International Nuclear Information System (INIS)

    Deng, H R; Liu, Y M; Ma, R F; Han, D Y; Gan, Z H; Pfotenhauer, J M

    2015-01-01

    The pulsating heat pipe (PHP) has been increasingly studied in cryogenic application, for its high transfer coefficient and quick response. Compared with Nb 3 Sn and NbTi, MgB 2 whose critical transformation temperature is 39 K, is expected to replace some high-temperature superconducting materials at 25 K. In order to cool MgB 2 , this paper designs a Hydrogen Pulsating Heat Pipe, which allows a study of applied heat, filling ratio, turn number, inclination angle and length of adiabatic section on the thermal performance of the PHP. The thermal performance of the hydrogen PHP is investigated for filling ratios of 35%, 51%, 70% at different heat inputs, and provides information regarding the starting process is received at three filling ratios. (paper)

  19. New student laboratory work about pulsational phenomena in astronomy

    Science.gov (United States)

    Nuritdinov, Salakhutdin N.

    The pulsation phenomenon is inherent to the most of the object types and it plays a great role at certain stages of the evolution of the Universe objects. That's why students must study this phenomenon in the framework of laboratory hours. Often the study of these phenomena is reduced to an analysis of some differential equations with variable coefficients. A class of these equations is connected with the stability problem of the self-gravitating system oscillations ( S.Nuritdinov, Sov. Astron., 1985, 29, 293) . In order to carry out this laboratory work every student is bound to compose a computer program using the periodical solution stability method and the parameter resonance theory. It will find critical amplitude of the pulsation and some dependences between physical parameters.

  20. Quantitative results of stellar evolution and pulsation theories.

    Science.gov (United States)

    Fricke, K.; Stobie, R. S.; Strittmatter, P. A.

    1971-01-01

    The discrepancy between the masses of Cepheid variables deduced from evolution theory and pulsation theory is examined. The effect of input physics on evolutionary tracks is first discussed; in particular, changes in the opacity are considered. The sensitivity of pulsation masses to opacity changes and to the ascribed values of luminosity and effective temperature are then analyzed. The Cepheid mass discrepancy is discussed in the light of the results already obtained. Other astronomical evidence, including the mass-luminosity relation for main sequence stars, the solar neutrino flux, and cluster ages are also considered in an attempt to determine the most likely source of error in the event that substantial mass loss has not occurred.

  1. Numerical study on transient local entropy generation in pulsating ...

    Indian Academy of Sciences (India)

    The simulations are extended to include different pulsating flow cases (sinusoidal flow, step flow, and saw-down flow) and for varying periods. The flow and temperature fields are computed numerically with the help of the Fluent computational fluid dynamics (CFD) code, and a computer program developed by us by using ...

  2. Effects of pulsating water jet impact on aluminium surface

    Czech Academy of Sciences Publication Activity Database

    Foldyna, Josef; Sitek, Libor; Ščučka, Jiří; Martinec, Petr; Valíček, Jan; Páleníková, K.

    2009-01-01

    Roč. 2009, č. 20 (2009), s. 6174-6180 ISSN 0924-0136 R&D Projects: GA ČR GA101/07/1451; GA ČR GP101/07/P512 Institutional research plan: CEZ:AV0Z30860518 Keywords : pulsating water jet * jet impact * material erosion * surface characteristics Subject RIV: JQ - Machines ; Tools Impact factor: 1.420, year: 2009 http://www.sciencedirect.com/science

  3. Decreasing of pulsation intensity levels in X-ray receivers

    CERN Document Server

    Dvoryankin, V F; Kudryashov, A A; Petrov, A G

    2002-01-01

    The low frequency filter is applied in the multichannel receiver on the basis of the GaAs epitaxial structures for decreasing the pulsations level at the signals amplifier outlet. The optimal band of the filter is determined by the transition processes by the detector scanning in the roentgen beams. The X-ray source of radiation with the medium-frequency feeding generator is used for verifying the quality of the obtained X-ray image

  4. Investigation of shock wave loading and crater creation by means of single and double targets in the PALS experiment

    Czech Academy of Sciences Publication Activity Database

    Gus'kov, S. Yu.; Borodziuk, S.; Kálal, M.; Kasperzcuk, A.; Kondrashov, V. N.; Limpouch, J.; Pisarczyk, T.; Rohlena, Karel; Skála, Jiří; Ullschmied, Jiří

    2005-01-01

    Roč. 26, č. 3 (2005), s. 228-244 ISSN 1071-2836 R&D Projects: GA MŠk LN00A100; GA AV ČR KSK2043105 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z10100523 Keywords : shock waves * hydrodynamic efficiency * ablation loading * interferometry * PALS Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.500, year: 2005

  5. Evaluation of crestal bone loss and stability of immediate functional loading versus immediate non-functional loading of single-mandibular posterior implants: A pilot randomized controlled clinical trial.

    Science.gov (United States)

    Mantena, Satyanarayana Raju; Sivagami, G; Gottumukkala, Sruthima Nvs

    2014-09-01

    The aim of this study is to evaluate and compare the crestal bone loss and stability of single mandibular posterior dental implants placed in immediate functional loading (IFL) and immediate nonfunctional loading (INFL) during 6 months after placement. Forty single piece root form titanium implants were placed in 20 patients using IFL and INFL techniques. The change in the level of crestal bone was measured on standardized digital periapical radiographs using SOPRO imaging software and stability of implants using resonance frequency analyser taken at the baseline, 1, 3, and 6 months. The measurements were statistically analyzed using the independent and paired t-test (P implant stability quotient (ISQ) values at first and third months were lower than those at the baseline for both the groups. However, the ISQ values at the sixth month were similar to baseline for both the groups. The crestal bone changes and the ISQ values when compared between the groups showed no statistically significant difference. IFL of dental implants have equivalent results and success rate as that of immediately provisionalized implants within the limitations of this study.

  6. Evaluation of crestal bone loss and stability of immediate functional loading versus immediate non-functional loading of single-mandibular posterior implants: A pilot randomized controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Satyanarayana Raju Mantena

    2014-01-01

    Full Text Available Background: The aim of this study is to evaluate and compare the crestal bone loss and stability of single mandibular posterior dental implants placed in immediate functional loading (IFL and immediate nonfunctional loading (INFL during 6 months after placement. Materials and Methods: Forty single piece root form titanium implants were placed in 20 patients using IFL and INFL techniques. The change in the level of crestal bone was measured on standardized digital periapical radiographs using SOPRO imaging software and stability of implants using resonance frequency analyser taken at the baseline, 1, 3, and 6 months. The measurements were statistically analyzed using the independent and paired t-test (P < 0.05, statistically significant. Results: The mean change in the crestal bone level from baseline to 6 months was significant in both techniques. The implant stability quotient (ISQ values at first and third months were lower than those at the baseline for both the groups. However, the ISQ values at the sixth month were similar to baseline for both the groups. The crestal bone changes and the ISQ values when compared between the groups showed no statistically significant difference. Conclusion: IFL of dental implants have equivalent results and success rate as that of immediately provisionalized implants within the limitations of this study.

  7. Performance comparison of single-stage mixed-refrigerant Joule–Thomson cycle and reverse Brayton cycle for cooling 80 to 120 K temperature-distributed heat loads

    Science.gov (United States)

    Wang, H. C.; Chen, G. F.; Gong, M. Q.; Li, X.

    2017-12-01

    Thermodynamic performance comparison of single-stage mixed-refrigerant Joule–Thomson cycle (MJTR) and pure refrigerant reverse Brayton cycle (RBC) for cooling 80 to 120 K temperature-distributed heat loads was conducted in this paper. Nitrogen under various liquefaction pressures was employed as the heat load. The research was conducted under nonideal conditions by exergy analysis methods. Exergy efficiency and volumetric cooling capacity are two main evaluation parameters. Exergy loss distribution in each process of refrigeration cycle was also investigated. The exergy efficiency and volumetric cooling capacity of MJTR were obviously superior to RBC in 90 to 120 K temperature zone, but still inferior to RBC at 80 K. The performance degradation of MJTR was caused by two main reasons: The high fraction of neon resulted in large entropy generation and exergy loss in throttling process. Larger duty and WLMTD lead to larger exergy losses in recuperator.

  8. Geomagnetic precursors of intensive earthquakes in the 1-0.-2 Hz frequency range of geomagnetic pulsations

    Science.gov (United States)

    Gogatishvili, Y. M.

    1985-02-01

    During intensive geotectonic processes such as earthquakes, pulsations are observed in the geomagnetic field at a frequency of 0.02 to 1 Hz with anomalously high amplitudes. These pulsations usually apppear as beat phenomena lasting from several minutes to several hours. It has been found that the pulsations are excited only in magnetic compontents of the terrestrial electromagnetic field. The periods and amplitudes of the pulsations are nonlinearly related to the intensity of the earthquakes. Pulsations of this type are not observed when earthquakes do not occur. Additional analysis shows that frequently the pulsations precede intensive earthquakes by 10 to 200 minutes, then drop for about 1 hour, then appear once again during the actual earthquake. Oscillograms of such pulsations are presented. The periods and amplitudes of the geomagnetic pulsations preceding earthquakes are found to be linearly related to the magnitude of the earthquakes. A regression equation relating earthquake magnitude to pulsation characteristics is presented.

  9. THE PULSATION MODE AND DISTANCE OF THE CEPHEID FF AQUILAE

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. G. [Department of Astronomy and Physics, Saint Mary' s University, Halifax, NS B3H 3C3 (Canada); Kovtyukh, V. V. [Astronomical Observatory, Odessa National University, and Isaac Newton Institute of Chile, Odessa Branch, T. G. Shevkenko Park, 65014 Odessa (Ukraine); Luck, R. E. [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7215 (United States); Berdnikov, L. N., E-mail: turner@ap.smu.ca, E-mail: val@deneb1.odessa.ua, E-mail: rel2@case.edu, E-mail: leonid.berdnikov@gmail.com [Sternberg Astronomical Institute, Moscow M. V. Lomonosov State University, Moscow 119992 (Russian Federation)

    2013-07-20

    The determination of pulsation mode and distance for field Cepheids is a complicated problem best resolved by a luminosity estimate. For illustration a technique based on spectroscopic luminosity discrimination is applied to the 4.47 day s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable yield values of (M{sub V} ) = -3.40 {+-} 0.02 s.e. ({+-}0.04 s.d.), average effective temperature T{sub eff} = 6195 {+-} 24 K, and intrinsic color ((B) - (V)){sub 0} = +0.506 {+-} 0.007, corresponding to a reddening of E{sub B-V} = 0.25 {+-} 0.01, or E{sub B-V}(B0) = 0.26 {+-} 0.01. The skewed light curve, intrinsic color, and luminosity of FF Aql are consistent with fundamental mode pulsation for a small-amplitude classical Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A distance of 413 {+-} 14 pc is estimated from the Cepheid's angular diameter in conjunction with a mean radius of (R) = 39.0 {+-} 0.7 R{sub Sun} inferred from its luminosity and effective temperature. The dust extinction toward FF Aql is described by a ratio of total-to-selective extinction of R{sub V} = A{sub V} /E(B - V) = 3.16 {+-} 0.34 according to the star's apparent distance modulus.

  10. Articulated pipes conveying fluid pulsating with high frequency

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    1999-01-01

    Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hangin...... is shown to affect the nonlinear behavior of the system, e.g. bifurcation types can change from supercritical to subcritical, creating several coexisting stable solutions and also anti-symmetrical flutter may appear.......Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hanging....... An approximate nonlinear solution for small-amplitude flutter oscillations is obtained using a fifth-order multiple scales perturbation method, and large-amplitude oscillations are examined by numerical integration of the autonomous model equations, using a path-following algorithm. The pulsating fluid component...

  11. Linear viral load increase of a single HPV-type in women with multiple HPV infections predicts progression to cervical cancer.

    Science.gov (United States)

    Depuydt, Christophe E; Thys, Sofie; Beert, Johan; Jonckheere, Jef; Salembier, Geert; Bogers, Johannes J

    2016-11-01

    Persistent high-risk human papillomavirus (HPV) infection is strongly associated with development of high-grade cervical intraepithelial neoplasia or cancer (CIN3+). In single type infections, serial type-specific viral-load measurements predict the natural history of the infection. In infections with multiple HPV-types, the individual type-specific viral-load profile could distinguish progressing HPV-infections from regressing infections. A case-cohort natural history study was established using samples from untreated women with multiple HPV-infections who developed CIN3+ (n = 57) or cleared infections (n = 88). Enriched cell pellet from liquid based cytology samples were subjected to a clinically validated real-time qPCR-assay (18 HPV-types). Using serial type-specific viral-load measurements (≥3) we calculated HPV-specific slopes and coefficient of determination (R(2) ) by linear regression. For each woman slopes and R(2) were used to calculate which HPV-induced processes were ongoing (progression, regression, serial transient, transient). In transient infections with multiple HPV-types, each single HPV-type generated similar increasing (0.27copies/cell/day) and decreasing (-0.27copies/cell/day) viral-load slopes. In CIN3+, at least one of the HPV-types had a clonal progressive course (R(2)  ≥ 0.85; 0.0025copies/cell/day). In selected CIN3+ cases (n = 6), immunostaining detecting type-specific HPV 16, 31, 33, 58 and 67 RNA showed an even staining in clonal populations (CIN3+), whereas in transient virion-producing infections the RNA-staining was less in the basal layer compared to the upper layer where cells were ready to desquamate and release newly-formed virions. RNA-hybridization patterns matched the calculated ongoing processes measured by R(2) and slope in serial type-specific viral-load measurements preceding the biopsy. In women with multiple HPV-types, serial type-specific viral-load measurements predict the natural history of the

  12. A 5-year comparison of marginal bone level following immediate loading of single-tooth implants placed in healed alveolar ridges and extraction sockets in the maxilla

    Science.gov (United States)

    Berberi, Antoine N.; Sabbagh, Joseph M.; Aboushelib, Moustafa N.; Noujeim, Ziad F.; Salameh, Ziad A.

    2014-01-01

    Purpose: The aim of present investigation was to evaluate marginal bone level after 5-year follow-up of implants placed in healed ridges and fresh extraction sockets in maxilla with immediate loading protocol. Materials and Methods: Thirty-six patients in need of a single-tooth replacement in the anterior maxilla received 42 Astra Tech implants (Astra Tech Implant system™, Dentsply Implants, Mölndal, Sweden). Implants were placed either in healed ridges (group I) or immediately into fresh extraction sockets (group II). Implants were restored and placed into functional loading immediately by using a prefabricated abutment. Marginal bone level relative to the implant reference point was recorded at implant placement, crown cementation, 12, 36, and 60 months following loading using intra-oral radiographs. Measurements were made on the mesial and distal sides of each implant. Results: Overall, two implants were lost from the group II, before final crown cementation: they were excluded from the study. The mean change in marginal bone loss (MBL) after implant placement was 0.26 ± 0.161 mm for 1 year, and 0.26 ± 0.171 mm for 3 years, and 0.21 ± 0.185 mm for 5 years in extraction sockets and was 0.26 ± 0.176 mm for 1 year and 0.21 ± 0.175 mm for 3 years, and 0.19 ± 0.172 mm for 5 years in healed ridges group. Significant reduction of marginal bone was more pronounced in implants inserted in healed ridges (P implant after cementation of the provisional (P immediately loaded implants placed either in extraction sockets or healed ridges were similar. Functional loading technique by using prefabricated abutment placed during the surgery time seems to maintain marginal bone around implant in both healed and fresh extraction sites. PMID:24550840

  13. A 5-year comparison of marginal bone level following immediate loading of single-tooth implants placed in healed alveolar ridges and extraction sockets in the maxilla.

    Science.gov (United States)

    Berberi, Antoine N; Sabbagh, Joseph M; Aboushelib, Moustafa N; Noujeim, Ziad F; Salameh, Ziad A

    2014-01-01

    The aim of present investigation was to evaluate marginal bone level after 5-year follow-up of implants placed in healed ridges and fresh extraction sockets in maxilla with immediate loading protocol. Thirty-six patients in need of a single-tooth replacement in the anterior maxilla received 42 Astra Tech implants (Astra Tech Implant system™, Dentsply Implants, Mölndal, Sweden). Implants were placed either in healed ridges (group I) or immediately into fresh extraction sockets (group II). Implants were restored and placed into functional loading immediately by using a prefabricated abutment. Marginal bone level relative to the implant reference point was recorded at implant placement, crown cementation, 12, 36, and 60 months following loading using intra-oral radiographs. Measurements were made on the mesial and distal sides of each implant. Overall, two implants were lost from the group II, before final crown cementation: they were excluded from the study. The mean change in marginal bone loss (MBL) after implant placement was 0.26 ± 0.161 mm for 1 year, and 0.26 ± 0.171 mm for 3 years, and 0.21 ± 0.185 mm for 5 years in extraction sockets and was 0.26 ± 0.176 mm for 1 year and 0.21 ± 0.175 mm for 3 years, and 0.19 ± 0.172 mm for 5 years in healed ridges group. Significant reduction of marginal bone was more pronounced in implants inserted in healed ridges (P implant after cementation of the provisional (P immediately loaded implants placed either in extraction sockets or healed ridges were similar. Functional loading technique by using prefabricated abutment placed during the surgery time seems to maintain marginal bone around implant in both healed and fresh extraction sites.

  14. Retrospective analysis of 56 edentulous dental arches restored with 344 single-stage implants using an immediate loading fixed provisional protocol: statistical predictors of implant failure.

    Science.gov (United States)

    Kinsel, Richard P; Liss, Mindy

    2007-01-01

    The purpose of this retrospective study was to evaluate the effects of implant dimensions, surface treatment, location in the dental arch, numbers of supporting implant abutments, surgical technique, and generally recognized risk factors on the survival of a series of single-stage Straumann dental implants placed into edentulous arches using an immediate loading protocol. Each patient received between 4 and 18 implants in one or both dental arches. Periapical radiographs were obtained over a 2- to 10-year follow-up period to evaluate crestal bone loss following insertion of the definitive metal-ceramic fixed prostheses. Univariate tests for failure rates as a function of age ( or = 60 years), gender, smoking, bone grafting, dental arch, surface type, anterior versus posterior, number of implants per arch, and surgical technique were made using Fisher exact tests. The Cochran-Armitage test for trend was used to evaluate the presence of a linear trend in failure rates regarding implant length and implant diameter. Logistic regression modeling was used to determine which, if any, of the aforementioned factors would predict patient and implant failure. A significance criterion of P = .05 was utilized. Data were collected for 344 single-stage implants placed into 56 edentulous arches (39 maxillae and 17 mandibles) of 43 patients and immediately loaded with a 1-piece provisional fixed prosthesis. A total of 16 implants failed to successfully integrate, for a survival rate of 95.3%. Increased rates of failure were associated with reduced implant length, placement in the posterior region of the jaw, increased implant diameter, and surface treatment. Implant length emerged as the sole significant predictor of implant failure. In this retrospective analysis of 56 consecutively treated edentulous arches with multiple single-stage dental implants loaded immediately, reduced implant length was the sole significant predictor of failure.

  15. White Dwarf Period Tables - I. Pulsators with hydrogen-dominated atmospheres

    OpenAIRE

    Bognár, Zs.; Sódor, Á.

    2016-01-01

    We aimed at collecting all known white dwarf pulsators with hydrogen-dominated atmospheres and list their main photometric and atmospheric parameters together with their pulsation periods and amplitudes observed at different epochs. For this purpose, we explored the pulsating white dwarf related literature with the systematic use of the SIMBAD and the NASA's Astrophysics Data System (ADS) databases. We summarized our results in four tables listing seven ZZ Ceti stars in detached white dwarf p...

  16. Investigation on the Possible Relationship between Magnetic Pulsations and Earthquakes

    Science.gov (United States)

    Jusoh, M.; Liu, H.; Yumoto, K.; Uozumi, T.; Takla, E. M.; Yousif Suliman, M. E.; Kawano, H.; Yoshikawa, A.; Asillam, M.; Hashim, M.

    2012-12-01

    The sun is the main source of energy to the solar system, and it plays a major role in affecting the ionosphere, atmosphere and the earth surface. The connection between solar wind and the ground magnetic pulsations has been proven empirically by several researchers previously (H. J. Singer et al., 1977, E. W. Greenstadt, 1979, I. A. Ansari 2006 to name a few). In our preliminary statistical analysis on relationship between solar and seismic activities (Jusoh and Yumoto, 2011, Jusoh et al., 2012), we observed a high possibility of solar-terrestrial coupling. We observed high tendency of earthquakes to occur during lower phase solar cycles which significantly related with solar wind parameters (i.e solar wind dynamic pressure, speed and input energy). However a clear coupling mechanism was not established yet. To connect the solar impact on seismicity, we investigate the possibility of ground magnetic pulsations as one of the connecting agent. In our analysis, the recorded ground magnetic pulsations are analyzed at different ranges of ultra low frequency; Pc3 (22-100 mHz), Pc4 (6.7-22 mHz) and Pc5 (1.7-6.7 mHz) with the occurrence of local earthquake events at certain time periods. This analysis focuses at 2 different major seismic regions; north Japan (mid latitude) and north Sumatera, Indonesia (low latitude). Solar wind parameters were obtained from the Goddard Space Flight Center, NASA via the OMNIWeb Data Explorer and the Space Physics Data Facility. Earthquake events were extracted from the Advanced National Seismic System (ANSS) database. The localized Pc3-Pc5 magnetic pulsations data were extracted from Magnetic Data Acquisition System (MAGDAS)/Circum Pan Magnetic Network (CPMN) located at Ashibetsu (Japan); for earthquakes monitored at north Japan and Langkawi (Malaysia); for earthquakes observed at north Sumatera. This magnetometer arrays has established by International Center for Space Weather Science and Education, Kyushu University, Japan. From the

  17. Cepheids in Magellanic Cloud star clusters - Fundamental and overtone pulsators in NGC 2157

    Science.gov (United States)

    Mateo, Mario; Olszewski, Edward W.; Madore, Barry F.

    1990-01-01

    CCD survey data are employed to examine Cepheids in young Magellanic Cloud star clusters. The properties of three Cepheids observed in NGC 2157 are described. It is detected that the two short-period (3 days) Cepheids have photometric properties that correspond to overtone pulsators and the long-period (7.7 days) Cepheid pulses in the fundamental mode. The pulsational masses for the three Cepheids are calculated to be about 5 solar masses. This mass value does not correlate with the average pulsational mass for Cepheids of 3.0 + or - 0.4 solar masses. The potential cause of this deviation in evolutionary/pulsational mass is investigated.

  18. Energies of precipitating electrons during pulsating aurora events derived from ionosonde observations

    International Nuclear Information System (INIS)

    MacDougall, J.W.; Hofstee, J.; Koehler, J.A.

    1981-01-01

    The time-history of particle energies and fluxes associated with pulsating auroras in the morning sector is derived from ionosonde measurements. All the pulsating auroras studied showed a similar history with the pulsations occurring during a time interval of the order of an hour during which the average auroral Maxwellian characteristic energy stays relatively constant but the energy flux decreases progressively during the event. A possible explanation for this behaviour in terms of an injection of particles into a magnetospheric 'bottle' near the midnight meridian and the progressive precipitation out of the bottle during the pulsating event is suggested. (auth)

  19. Time-Series Spectroscopy and Photometry of the Helium Atmosphere Pulsating White Dwarf EC 20058-5234

    Science.gov (United States)

    Sullivan, D. J.

    2017-03-01

    We summarise both photometric and spectroscopic observations of the southern DBV white dwarf EC 20058-5234 (QU Tel) obtained primarily using a Magellan 6.5 m telescope. With the aim of identifying pulsation-induced spectral variations, the time-resolved 30 sMagellan spectra are phased using 54 h of contiguous time-series photometry obtained using the Mt John (NZ) 1.0 m telescope. A comparison of the DFTs obtained from a 1997 nine day multisite WET run and the two day single site Magellan observations is made. The difficulty of establishing a reliable surface temperatures for DBVs is mentioned.

  20. Immediate functional loading of single-tooth TiO2 grit-blasted implant restoration. A controlled prospective study in a porcine model. Part II: Histology and histomorphometry.

    NARCIS (Netherlands)

    Bousdras, V.A.; Walboomers, F.; Jansen, J.A.; Cunningham, J.L.; Blunn, G.; Petrie, A.; Jaecques, S.V.; Naert, I.E.; Sindet-Pedersen, S.; Goodship, A.E.

    2007-01-01

    BACKGROUND: Evidently, there is a fast-moving shift from delayed to immediate implant loading. The hypothesis to be tested was that bone reactions adjacent to single TiO2-microthreaded implants exposed to immediate masticatory loading for 10 weeks after placement would modulate osseointegration.

  1. Immediate loading and customized restoration of a single implant in the maxillary esthetic zone : A clinical report

    NARCIS (Netherlands)

    den Hartog, Laurens; Raghoebar, Gerry M.; Stellingsma, Kees; Meijer, Henny J. A.

    2009-01-01

    The replacement of a single missing anterior tooth with an implant-supported crown Is a demanding therapy. This report describes a treatment in which an anterior maxillary implant was immediately restored with a provisional restoration. During the provisional phase, an optimal emergence profile was

  2. Low-Complexity Model Predictive Control of Single-Phase Three-Level Rectifiers with Unbalanced Load

    DEFF Research Database (Denmark)

    Ma, Junpeng; Song, Wensheng; Wang, Xiongfei

    2018-01-01

    The fluctuation of the neutral-point potential in single-phase three-level rectifiers leads to coupling between the line current regulation and dc-link voltage balancing, deteriorating the quality of line current. For addressing this issue, this paper proposes a low-complexity model predictive...

  3. Single-tooth replacement in the anterior maxilla by means of immediate implantation and early loading: clinical and aesthetic results at 5 years.

    Science.gov (United States)

    Guarnieri, Renzo; Ceccherini, Alessandro; Grande, Maurizio

    2015-04-01

    The hypothesis of the present study was that the early loading of single implants-supported restorations, replacing single extracting teeth in the anterior region of the maxilla in case of fresh extraction sockets with residual hard and soft tissue preservation, could be a successful procedure. Twenty-one implants were placed into maxillary anterior fresh extraction sockets using a flapless technique. Temporary restorations, which were fabricated from the impression taken immediately after implant placement, were connected within 2 weeks. These temporary restorations were adjusted in order to avoid any direct occlusive contacts. Six months after implantation, the implants were restored with single-teeth all-ceramic prostheses. Patients were followed for 5 years. Radiographic and clinical examinations were made at baseline, at time of definitive crowns delivery, and each subsequent year. Survival rate, cortical bone responses, and peri-implant mucosal responses were evaluated. One implant was lost at 6 months. Clinical osseointegration of 20 implants was achieved (95.2% implant survival rate after 5 years) with minimal gingival recession and papillae preservation. The mean change in marginal cortical bone level was 0.40 mm at 6 months and 0.83 mm at 5 years. Within the limit of the present study, the data indicate that, under a strictly controlled oral hygienic regimen, single-tooth implants, with immediate placement and early loading protocol, may be used in anterior maxillary fresh extraction sockets with residual hard and soft tissues preservation, if patients are selected carefully and if high primary stability is strictly followed. © 2013 Wiley Periodicals, Inc.

  4. Sound spectrum of a pulsating optical discharge

    Energy Technology Data Exchange (ETDEWEB)

    Grachev, G N; Smirnov, A L; Tishchenko, V N [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Dmitriev, A K; Miroshnichenko, I B [Novosibirsk State Technical University (Russian Federation)

    2016-02-28

    A spectrum of sound of an optical discharge generated by a repetitively pulsed (RP) laser radiation has been investigated. The parameters of laser radiation are determined at which the spectrum of sound may contains either many lines, or the main line at the pulse repetition rate and several weaker overtones, or a single line. The spectrum of sound produced by trains of RP radiation comprises the line (and overtones) at the repetition rate of train sequences and the line at the repetition rate of pulses in trains. A CO{sub 2} laser with the pulse repetition rate of f ≈ 3 – 180 kHz and the average power of up to 2 W was used in the experiments. (optical discharges)

  5. Sinus Floor Elevation with Modified Crestal Approach and Single Loaded Short Implants: A Case Report with 4 Years of Follow-Up

    Directory of Open Access Journals (Sweden)

    Michele Perelli

    2017-01-01

    Full Text Available Tooth extraction is usually followed by bone reduction. In the maxillary posterior region, this remodelling combined with sinus pneumatisation and periodontal defects may lead to a reduced basal bone height available for implant placement. Sinus floor elevation can be performed with different surgical techniques. Crestal approach has demonstrated to be effective, less invasive, and associated with a reduced morbidity. This article reports a modified sinus floor elevation by means of rotary, noncutting instruments, addition of xenograft, and 2 short-threaded implant placements. The aim of the study was to evaluate the implant’s success and intrasinus radiographical bone gain after 4 years of functional loading. The premolar implant site presented a starting basal bone height of 6 mm, while the molar site was of 2 mm. In the first surgical step, sinus floor elevation was performed mesially and the implant was inserted, and distally only sinus floor elevation was performed. After 6 months, the mesial implant was uncovered and the second implant was inserted; 4 months later, the second fixture was uncovered, and both fixtures were loaded with single provisional screw-retained crowns and later with single screw-retained porcelain fused to metal crowns. Implants integrated successfully, and crestal bone remodelling did not exceed the smooth collar. Bone gain was 3 mm for the mesial implant and more than 5 mm for the distal one.

  6. Behavior of instantaneous lateral velocity and flow pulsation in duct flow with cylindrical rod

    International Nuclear Information System (INIS)

    Lee, Chi Young; Shin, Chang Hwan; Park, Ju Yong; Oh, Dong Seok; Chun, Tae Hyun; In, Wang Kee

    2012-01-01

    pulsation in single rod-inserted duct flow is reported and discussed, using various W/D (wall distance between wall and rod to rod diameter ratio) cases

  7. A Computational Study for the Utilization of Jet Pulsations in Gas Turbine Film Cooling and Flow Control

    Science.gov (United States)

    Kartuzova, Olga V.

    2012-01-01

    This report is the second part of a three-part final report of research performed under an NRA cooperative Agreement contract. The first part is NASA/CR-2012-217415. The third part is NASA/CR-2012-217417. Jets have been utilized in various turbomachinery applications in order to improve gas turbines performance. Jet pulsation is a promising technique because of the reduction in the amount of air removed from compressor. In this work two areas of pulsed jets applications were computationally investigated using the commercial code Fluent (ANSYS, Inc.); the first one is film cooling of High Pressure Turbine (HPT) blades and second one is flow separation control over Low Pressure Turbine (LPT) airfoil using Vortex Generator Jets (VGJ). Using pulsed jets for film cooling purposes can help to improve the effectiveness and thus allow higher turbine inlet temperature. Effects of the film hole geometry, blowing ratio and density ratio of the jet, pulsation frequency and duty cycle of blowing on the film cooling effectiveness were investigated. As for the low-pressure turbine (LPT) stages, the boundary layer separation on the suction side of airfoils can occur due to strong adverse pressure gradients. The problem is exacerbated as airfoil loading is increased. Active flow control could provide a means for minimizing separation under conditions where it is most severe (low Reynolds number), without causing additional losses under other conditions (high Reynolds number). The effects of the jet geometry, blowing ratio, density ratio, pulsation frequency and duty cycle on the size of the separated region were examined in this work. The results from Reynolds Averaged Navier-Stokes and Large Eddy Simulation computational approaches were compared with the experimental data.

  8. A 5- Year Comparison of Marginal Bone Level Following Immediate Loading of Single-Tooth Implants Placed in Healed Alveolar Ridges and Extraction Sockets in the Maxilla.

    Directory of Open Access Journals (Sweden)

    Antoine Nicolas Berberi

    2014-01-01

    Full Text Available AbstractPurpose: The aim of present investigation was to evaluate marginal bone level after 5-year follow-up of implants placed in healed ridges and fresh extraction sockets in maxilla with immediate loading protocol.Materials and Methods: Thirty-six patients in need of a single tooth replacement in the anterior maxilla received 42 Astra Tech implants (Astra Tech Implant system™, Dentsply Implants, Mölndal, Sweden. Implants were placed in healed ridges (group I or immediately into extraction sockets (group II. Implants were restored and placed into functional loading immediately by using a prefabricated abutment. Marginal bone level relative to the implant reference point was recorded at implant placement, crown cementation, 12, 36 and 60 months following loading using intra-oral radiographs. Measurements were made on the mesial and distal sides of each implantResults: Overall, two implants were lost from the group II, before final crown cementation: they were excluded from the study and all remaining implants osseointegrated successfully after 5 years of functional loading. The mean change in marginal bone loss after implant placement was 0.267±0.161 for one year, and 0.265±0.171 for three years and 0.213±0.185 for five years in extraction sockets and was 0.266±0.176 for one year and 0.219±0.175 for three years and 0.194±0.172 for five years in healed ridges group. Significant reduction of marginal bone loss was more pronounced in implants inserted in healed ridges (P

  9. Performance of the tariffs of a single-phase electric energy meter, type electronic, operating with non-linear loads; Desempenho tarifario do medidor monofasico de energia eletrica do tipo eletronico operando com cargas nao-lineares

    Energy Technology Data Exchange (ETDEWEB)

    Santos, G.B.; Pinheiro Neto, D.; Lisita, L.R.; Machado, P.C.M.; Oliveira, J.V.M. [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Escola de Engenharia Eletrica e de Computacao], Emails: guilhermebsantos@gmail.com, daywes@gmail.com, lrlisi-ta@gmail.com, pcesar@eee.ufg.br, joao.eee@gmail.com

    2009-07-01

    This paper analyzes the behavior of a electronic meter of single-phase in the laboratory when it is subjected to a environment with linear loads and nonlinear loads kind residential and commercial. It differs from correlated studies mainly for making use of real loads encountered in day-to-day, rather than as sources of electronic loads how has been observed in the state of the art. The comparison of results is made based on high precision energy pattern developed by virtual instrumentation means.

  10. Mandibular single-implant overdentures: preliminary results of a randomised-control trial on early loading with different implant diameters and attachment systems.

    Science.gov (United States)

    Alsabeeha, Nabeel H M; Payne, Alan G T; De Silva, Rohana K; Thomson, W Murray

    2011-03-01

    To determine surgical and prosthodontic outcomes of mandibular single-implant overdentures, opposing complete maxillary dentures, using a wide diameter implant and large ball attachment system compared with different regular diameter implants with standard attachment systems. Thirty-six edentulous participants (mean age 68 years, SD 9.2) were randomly assigned into three treatment groups (n=12). A single implant was placed in the mandibular midline of participants to support an overdenture using a 6-week loading protocol. The control group received Southern regular implants and standard ball attachments. One group received Southern 8-mm-wide implants and large ball attachments. Another group received Neoss regular implants and Locator attachments. Parametric and non-parametric tests of a statistical software package (SPSS) were used to determine between groups differences in marginal bone loss, implant stability, implant, and prosthodontic success (PImplant success after 1 year was 75% for Southern regular implant (control) group; and 100% for the Southern wide and Neoss regular implant groups (P=0.038). Mean marginal bone loss at 1 year was 0.19 mm (SD 0.39) without significant differences observed. Implant stability quotient (ISQ) at baseline was significantly lower for the Southern regular (control) group than the other two groups (P=0.001; P=0.009). At 1 year, no significant difference in implant stability was observed (mean ISQ 74.6, SD 6.1). The change in implant stability from baseline to 1 year was significant for the control group (P=0.025). Prosthodontic success was comparable between the groups but the maintenance (41 events overall, mean 1.2) was greater for the Locator and the standard ball attachments. Mandibular single-implant overdentures are a successful treatment option for older edentulous adults with early loading protocol using implants of different diameters and with different attachment systems. © 2010 John Wiley & Sons A/S.

  11. Four new massive pulsating white dwarfs including an ultramassive DAV

    Science.gov (United States)

    Curd, Brandon; Gianninas, A.; Bell, Keaton J.; Kilic, Mukremin; Romero, A. D.; Allende Prieto, Carlos; Winget, D. E.; Winget, K. I.

    2017-06-01

    We report the discovery of four massive (M > 0.8 M⊙) ZZ Ceti white dwarfs, including an ultramassive 1.16 M⊙ star. We obtained ground-based, time series photometry for 13 white dwarfs from the Sloan Digital Sky Survey Data Release 7 and Data Release 10 whose atmospheric parameters place them within the ZZ Ceti instability strip. We detect monoperiodic pulsations in three of our targets (J1015, J1554 and J2038) and identify three periods of pulsation in J0840 (173, 327 and 797 s). Fourier analysis of the remaining nine objects does not indicate variability above the 4 detection threshold. Our preliminary asteroseismic analysis of J0840 yields a stellar mass M = 1.14 ± 0.01 M⊙, hydrogen and helium envelope masses of MH = 5.8 × 10-7 M⊙ and MHe = 4.5 × 10-4 M⊙ and an expected core crystallized mass ratio of 50-70 per cent. J1015, J1554 and J2038 have masses in the range 0.84-0.91 M⊙ and are expected to have a CO core; however, the core of J0840 could consist of highly crystallized CO or ONeMg given its high mass. These newly discovered massive pulsators represent a significant increase in the number of known ZZ Ceti white dwarfs with mass M > 0.85 M⊙, and detailed asteroseismic modelling of J0840 will allow for significant tests of crystallization theory in CO and ONeMg core white dwarfs.

  12. Appraisal of electromagnetic induction effects on magnetic pulsation studies

    Directory of Open Access Journals (Sweden)

    B. R. Arora

    Full Text Available The quantification of wave polarization characteristics of ULF waves from the geomagnetic field variations is done under ‘a priori’ assumption that fields of internal induced currents are in-phase with the external inducing fields. Such approximation is invalidated in the regions marked by large lateral conductivity variations that perturb the flow pattern of induced currents. The amplitude and phase changes that these perturbations produce, in the resultant fields at the Earth’s surface, make determination of polarization and phase of the oscillating external signals problematic. In this paper, with the help of a classical Pc5 magnetic pulsation event of 24 March 1991, recorded by dense network of magnetometers in the equatorial belt of Brazil, we document the nature and extent of the possible influence of anomalous induction effects in the wave polarization of ULF waves. The presence of anomalous induction effects at selected sites lead to an over estimation of the equatorial enhancement at pulsation period and also suggest changes in the azimuth of ULF waves as they propagate through the equatorial electrojet. Through numerical calculations, it is shown that anomalous horizontal fields, that result from induction in the lateral conductivity distribution in the study region, vary in magnitude and phase with the polarization of external source field. Essentially, the induction response is also a function of the period of external inducing source field. It is further shown that when anomalous induction fields corresponding to the magnitude and polarization of the 24 March 1991 pulsation event are eliminated from observed fields, corrected amplitude in the X and Y horizontal components allows for true characterisation of ULF wave parameters.

    Key words. Geomagnetism and paleomagnetism (geomagnetic induction – Ionosphere (equatorial ionosphere – Magnetospheric physics (magnetosphere-ionosphere interactions

  13. The domains of instability for the pulsating PG1159 stars.

    Energy Technology Data Exchange (ETDEWEB)

    Quirion, P.-O.; Fontaine, Gilles.; Brassard, Pierre; Herwig, F. H. (Falk H.)

    2004-01-01

    The fact that we find pulsating and nonpulsating stars mixed together in the PG 1159 region of the log g - T{sub eff} diagram has been a long standing puzzle. The poor understanding of the driving mechanism in those stars has been the reason why it has taken so long to address properly this problem. Following the work of Saio (1996) and Gautschy (1997) based on the OPAL opacities, Quirion, Fontaine, & Brassard (2004) recently showed that we are now able to understand and reproduce the ranges of observed periods in the pulsating PG 1159 stars in terms of the original {kappa}-mechanism associated with the partial ionization of the K-shell electrons of C and O which, along with He, make up the composition of the envelope of those stars. Contrary to others, those three studies agree in that no composition gradients are needed between the atmospheric layers and the driving region. Furthermore, the cohabitation of pulsating and nonpulsating PG 1159 stars is naturally explained in terms of a dispersion in atmospheric parameters and in terms of a variation in surface composition from star to star. In particular, the most He-rich stars tend to be stable. We go beyond the findings discussed by Quirion et al. (2004) in this paper, and present the results of additional calculations aimed at describing better the role of the chemical composition (in particular the role of metallicity) as well as that of the stellar mass on the boundaries of the instability domain in the log g - T{sub eff} plane.

  14. Mesospheric ozone destruction by high-energy electron precipitation associated with pulsating aurora

    Science.gov (United States)

    Turunen, Esa; Kero, Antti; Verronen, Pekka T.; Miyoshi, Yoshizumi; Oyama, Shin-Ichiro; Saito, Shinji

    2016-10-01

    Energetic particle precipitation into the upper atmosphere creates excess amounts of odd nitrogen and odd hydrogen. These destroy mesospheric and upper stratospheric ozone in catalytic reaction chains, either in situ at the altitude of the energy deposition or indirectly due to transport to other altitudes and latitudes. Recent statistical analysis of satellite data on mesospheric ozone reveals that the variations during energetic electron precipitation from Earth's radiation belts can be tens of percent. Here we report model calculations of ozone destruction due to a single event of pulsating aurora early in the morning on 17 November 2012. The presence of high-energy component in the precipitating electron flux (>200 keV) was detected as ionization down to 68 km altitude, by the VHF incoherent scatter radar of European Incoherent Scatter (EISCAT) Scientific Association (EISCAT VHF) in Tromsø, Norway. Observations by the Van Allen Probes satellite B showed the occurrence of rising tone lower band chorus waves, which cause the precipitation. We model the effect of high-energy electron precipitation on ozone concentration using a detailed coupled ion and neutral chemistry model. Due to a 30 min, recorded electron precipitation event we find 14% odd oxygen depletion at 75 km altitude. The uncertainty of the higher-energy electron fluxes leads to different possible energy deposition estimates during the pulsating aurora event. We find depletion of odd oxygen by several tens of percent, depending on the precipitation characteristics used in modeling. The effect is notably maximized at the sunset time following the occurrence of the precipitation.

  15. Stellar Pulsations and Stellar Evolution: Conflict, Cohabitation, or Symbiosis?

    Science.gov (United States)

    Weiss, Achim

    While the analysis of stellar pulsations allows the determination of current properties of a star, stellar evolution models connect it with its previous history. In many cases results from both methods do not agree. In this review some classical and current cases of disagreement are presented. In some cases these conflicts led to an improvement of the theory of stellar evolution, while in others they still remain unsolved. Some well-known problems of stellar physics are pointed out as well, for which it is hoped that seismology—or in general the analysis of stellar pulsations—will help to resolve them. The limits of this symbiosis will be discussed as well.

  16. Dissipative double-well potential: Nonlinear stationary and pulsating modes

    International Nuclear Information System (INIS)

    Zezyulin, Dmitry A.; Konotop, Vladimir V.; Alfimov, Georgy L.

    2010-01-01

    The analysis of nonlinear modes in a complex absorbing double-well potential supported by linear gain is presented. Families of the nonlinear modes and their bifurcations are found numerically by means of the properly modified 'shooting' method. Linear stability and dynamics of the modes are studied. It is shown that no stable modes exist in the case of attractive nonlinearity, while stable modes, including nonsymmetric ones, are found when the nonlinearity is repulsive. Varying a control parameter (e.g., the height of barrier between the wells) results in switching from one mode to another. Apart from stationary modes we have found pulsating solutions emergent from unstable modes.

  17. Analytical and molecular dynamics studies on the impact loading of single-layered graphene sheet by fullerene

    Science.gov (United States)

    Hosseini-Hashemi, Shahrokh; Sepahi-Boroujeni, Amin; Sepahi-Boroujeni, Saeid

    2018-04-01

    Normal impact performance of a system including a fullerene molecule and a single-layered graphene sheet is studied in the present paper. Firstly, through a mathematical approach, a new contact law is derived to describe the overall non-bonding interaction forces of the "hollow indenter-target" system. Preliminary verifications show that the derived contact law gives a reliable picture of force field of the system which is in good agreements with the results of molecular dynamics (MD) simulations. Afterwards, equation of the transversal motion of graphene sheet is utilized on the basis of both the nonlocal theory of elasticity and the assumptions of classical plate theory. Then, to derive dynamic behavior of the system, a set including the proposed contact law and the equations of motion of both graphene sheet and fullerene molecule is solved numerically. In order to evaluate outcomes of this method, the problem is modeled by MD simulation. Despite intrinsic differences between analytical and MD methods as well as various errors arise due to transient nature of the problem, acceptable agreements are established between analytical and MD outcomes. As a result, the proposed analytical method can be reliably used to address similar impact problems. Furthermore, it is found that a single-layered graphene sheet is capable of trapping fullerenes approaching with low velocities. Otherwise, in case of rebound, the sheet effectively absorbs predominant portion of fullerene energy.

  18. Thermal-diffusional Instability in White Dwarf Flames: Regimes of Flame Pulsation

    Science.gov (United States)

    Xing, Guangzheng; Zhao, Yibo; Modestov, Mikhail; Zhou, Cheng; Gao, Yang; Law, Chung K.

    2017-05-01

    Thermal-diffusional pulsation behaviors in planar as well as outwardly and inwardly propagating white dwarf (WD) carbon flames are systematically studied. In the 1D numerical simulation, the asymptotic degenerate equation of state and simplified one-step reaction rates for nuclear reactions are used to study the flame propagation and pulsation in WDs. The numerical critical Zel’dovich numbers of planar flames at different densities (ρ = 2, 3, and 4 × 107 g cm-3) and of spherical flames (with curvature c = -0.01, 0, 0.01, and 0.05) at a particular density (ρ = 2 × 107 g cm-3) are presented. Flame front pulsation in different environmental densities and temperatures are obtained to form the regime diagram of pulsation, showing that carbon flames pulsate in the typical density of 2 × 107 g cm-3 and temperature of 0.6 × 109 K. While being stable at higher temperatures, at relatively lower temperatures, the amplitude of the flame pulsation becomes larger. In outwardly propagating spherical flames the pulsation instability is enhanced and flames are also easier to quench due to pulsation at small radius, while the inwardly propagating flames are more stable.

  19. Pulsations in surf zone currents on a high energy mesotidal beach in New Zealand

    NARCIS (Netherlands)

    Gallop, S.L.; Bryan, K.R.; Pitman, S.J.; Ranasinghe, Ranasinghe W M R J B; Sandwell, D.

    2016-01-01

    The exchange of material between the surf zone and continental shelf can be driven by pulsations in rip current velocities. However, there is a poor understanding of the relationship of these pulsations to surf zone morphology and material exchange. Moreover, understanding of rip current dynamics

  20. Continuous versus pulsating flow boiling. Experimental comparison, visualization, and statistical analysis

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2017-01-01

    This experimental study investigates an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The hypothesis is that pulsations increase the flow boiling heat transfer by means of better bulk fluid mixing, increased wall wetting, and flow-regime destabilization...

  1. Continuous vs. pulsating flow boiling. Part 1: Experimental comparison and visualization

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2016-01-01

    This experimental study investigates an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The hypothesis is that pulsations increase the flow boiling heat transfer by means of better bulk fluid mixing, increased wall wetting and flow-regime destabilization...

  2. Ultracam Photometry of Pulsating Subdwarf B Stars rf B Binaries in the Edinburgh-Cape Survey

    NARCIS (Netherlands)

    Jeffery, C.S.; Aerts, C.C.; Dhillon, V.S.; Marsh, T.R.; Morales-Rueda, L.; Maxted, P.F.L.; Kilkenny, D.; O'Donoghue, D.

    2006-01-01

    High-speed multicolor photometry with ultracam promises to revolutionize the study of pulsating subdwarf B stars. As well as providing high S/N light curves with excellent temporal resolution, color amplitude ratios may be used to discriminate between different pulsation modes. In this paper we

  3. Thermal-diffusional Instability in White Dwarf Flames: Regimes of Flame Pulsation

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Guangzheng; Zhao, Yibo; Zhou, Cheng; Gao, Yang; Law, Chung K. [Center for Combustion Energy, Tsinghua University, Beijing 100084 (China); Modestov, Mikhail, E-mail: gaoyang-00@mails.tsinghua.edu.cn [Nordita, KTH Royal Institute of Technology and Stockholm University, SE-10691, Stockholm (Sweden)

    2017-05-20

    Thermal-diffusional pulsation behaviors in planar as well as outwardly and inwardly propagating white dwarf (WD) carbon flames are systematically studied. In the 1D numerical simulation, the asymptotic degenerate equation of state and simplified one-step reaction rates for nuclear reactions are used to study the flame propagation and pulsation in WDs. The numerical critical Zel’dovich numbers of planar flames at different densities ( ρ = 2, 3, and 4 × 10{sup 7} g cm{sup −3}) and of spherical flames (with curvature c = −0.01, 0, 0.01, and 0.05) at a particular density ( ρ = 2 × 10{sup 7} g cm{sup −3}) are presented. Flame front pulsation in different environmental densities and temperatures are obtained to form the regime diagram of pulsation, showing that carbon flames pulsate in the typical density of 2 × 10{sup 7} g cm{sup −3} and temperature of 0.6 × 10{sup 9} K. While being stable at higher temperatures, at relatively lower temperatures, the amplitude of the flame pulsation becomes larger. In outwardly propagating spherical flames the pulsation instability is enhanced and flames are also easier to quench due to pulsation at small radius, while the inwardly propagating flames are more stable.

  4. Connection between nonradial pulsations and stellar winds in massive stars. IV. Atmospheric structure and mass loss from pulsation with speculative application to B and Be stars

    International Nuclear Information System (INIS)

    Willson, L.A.

    1986-01-01

    Pulsation produces alterations in the density structure of a stellar atmosphere, and it drives or enhances mass loss. A summary is provided of some very general results which were obtained on the basis of an analysis of models calculated by Bowen (1985) for the atmospheres of radially pulsating cool stars. It is pointed out that four parameters are needed to characterize the structure of the atmosphere of a pulsating star, if simplifying assumptions are made regarding isothermal conditions with respect to shocks and the global temperature distribution. Some possible implications of the nonradial pulsations observed in B and Be stars for the structure of their atmospheres are discussed. Attention is given to the stellar wind, and applications to B and Be stars. 9 references

  5. Design optimization of a linear permanent magnet synchronous motor for extra low force pulsations

    International Nuclear Information System (INIS)

    Isfahani, Aarsh Hassanpour; Vaez-Zadeh, Sadegh

    2007-01-01

    Air cored linear permanent magnet synchronous motors have essentially low force pulsations due to the lack of the primary iron core and teeth. However, a motor design with much lower force pulsations is required for many precise positioning systems, as in fabrication of microelectronic chips. This paper presents the design optimization of an air cored linear permanent magnet synchronous motor with extra low force pulsations for such applications. In order to achieve the goal, an analytical layer model of the machine is developed. A very effective objective function regarding force pulsations is then proposed; while the selected motor dimensions are regarded as the design variables. A genetic algorithm is used to find the optimal motor dimensions. This results in a substantial ninety percent reduction in the force pulsations. The design optimization is verified by a finite element method

  6. Searching for X-ray Pulsations from Neutron Stars Using NICER

    Science.gov (United States)

    Ray, Paul S.; Arzoumanian, Zaven; Gendreau, Keith C.; Bogdanov, Slavko; Bult, Peter; Chakrabarty, Deepto; Chakrabarty, Deepto; Guillot, Sebastien; Harding, Alice; Ho, Wynn C. G.; Lamb, Frederick; Mahmoodifar, Simin; Miller, Cole; Strohmayer, Tod; Wilson-Hodge, Colleen; Wolff, Michael T.; NICER Science Team Working Group on Pulsation Searches and Multiwavelength Coordination

    2018-01-01

    The Neutron Star Interior Composition Explorer (NICER) presents an exciting new capability for discovering new modulation properties of X-ray emitting neutron stars, including large area, low background, extremely precise absolute time stamps, superb low-energy response and flexible scheduling. The Pulsation Searches and Multiwavelength Coordination working group has designed a 2.5 Ms observing program to search for pulsations and characterize the modulation properties of about 30 known or suspected neutron star sources across a number of source categories. A key early goal will be to search for pulsations from millisecond pulsars that might exhibit thermal pulsations from the surface suitable for pulse profile modeling to constrain the neutron star equation of state. In addition, we will search for pulsations from transitional millisecond pulsars, isolated neutron stars, LMXBs, accretion-powered millisecond pulsars, central compact objects and other sources. We present our science plan and initial results from the first months of the NICER mission.

  7. Frequency of common bile duct motion artifacts caused by inferior vena cava pulsation on magnetic resonance cholangiopancreatography

    International Nuclear Information System (INIS)

    Morita, Satoru; Ueno, Eiko; Saito, Naoko

    2008-01-01

    We assessed the frequency of common bile duct (CBD) motion artifacts caused by inferior vena cava (IVC) pulsation on magnetic resonance cholangiopancreatography (MRCP). We retrospectively evaluated CBD motion artifacts in 4 MRCP sequences from each of 115 consecutive patients. We observed 37 (32.2%) ghost artifacts at the ventral and dorsal aspects of the CBD on transaxial, half-Fourier acquisition single-shot turbo spin-echo (HASTE-ax) images; no such artifacts were observed on transaxial T 2 -weighted turbo spin-echo images. In 10 patients, we observed 9 (7.8%) pseudo-defects of the CBD on 3-dimensional T 2 -weighted turbo spin-echo with navigator-triggered prospective acquisition correction technique MRCP and 6 (5.2%) pseudo-defects on single-shot rapid acquisition with relaxation enhancement MRCP. Pseudo-defects were significantly more frequent in patients with ghost artifacts than without (9 of 37 [24.3%] versus one of 78 [1.3%]; P<0.01, McNemar test). Although uncommon, pseudo-defects of the CBD caused by IVC pulsation are observed on MRCP. MRCP interpretation that includes comparison with HASTE-ax images can diminish the potential misinterpretation of such CBD motion artifact as bile duct tumor or biliary stone. (author)

  8. Ventricular dilation and elevated aqueductal pulsations in a new experimental model of communicating hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Wagshul, M.; Smith, S.; Wagshul, M.; McAllister, J.P.; Rashid, S.; Li, J.; Egnor, M.R.; Walker, M.L.; Yu, M.; Smith, S.D.; Zhang, G.; Chen, J.J.; Beneveniste, H.

    2009-03-01

    In communicating hydrocephalus (CH), explanations for the symptoms and clear-cut effective treatments remain elusive. Pulsatile flow through the cerebral aqueduct is often significantly elevated, but a clear link between abnormal pulsations and ventriculomegaly has yet to be identified. We sought to demonstrate measurement of pulsatile aqueductal flow of CSF in the rat, and to characterize the temporal changes in CSF pulsations in a new model of CH. Hydrocephalus was induced by injection of kaolin into the basal cisterns of adult rats (n = 18). Ventricular volume and aqueductal pulsations were measured on a 9.4 T MRI over a one month period. Half of the animals developed ventricular dilation, with increased ventricular volume and pulsations as early as one day post-induction, and marked chronic elevations compared to intact controls (volume: 130.15 {+-} 83.21 {mu}l vs. 15.52 {+-} 2.00 {mu}l; pulsations: 114.51 nl {+-} 106.29 vs. 0.72 {+-} 0.13 nl). Similar to the clinical presentation, the relationship between ventricular size and pulsations was quite variable. However, the pulsation time-course revealed two distinct sub-types of hydrocephalic animals: those with markedly elevated pulsations which persisted over time, and those with mildly elevated pulsations which returned to near normal levels after one week. These groups were associated with severe and mild ventriculomegaly respectively. Thus, aqueductal flow can be measured in the rat using high-field MRI and basal cistern-induced CH is associated with an immediate change in CSF pulsatility. At the same time, our results highlight the complex nature of aqueductal pulsation and its relationship to ventricular dilation.

  9. Characterization of ultra low frequency (ULF pulsations and the investigation of their possible source

    Directory of Open Access Journals (Sweden)

    S. H. Mthembu

    2009-08-01

    Full Text Available In this paper we present the results from the observation of ultra low frequency (ULF pulsations in the Doppler velocity data from SuperDARN HF radar located at Goose Bay (61.94° N, 23.02° E, geomagnetic. Fourier spectral techniques were used to determine the spectral content of the data and the results show Pc 5 ULF pulsations (with a frequency range of 1 to 4 mHz where the magnetic field lines were oscillating at discrete frequencies of about 1.3 and 1.9 mHz. These pulsations are classified as field lines resonance (FLR since the 1.9 mHz component exhibited an enhancement in amplitude with an associated phase change of approximately 180° across a resonance latitude of 71.3°. The spatial and temporal structure of the ULF pulsations was examined by investigating their instantaneous amplitude which was calculated as the amplitude of the analytic signal. The results presented a full field of view which exhibit pulsations activity simultaneously from all beams. This representation shows that the peak amplitude of the 1.9 mHz component was observed over the longitudinal range of 13°. The temporal structure of the pulsations was investigated from the evolution of the 1.9 mHz component and the results showed that the ULF pulsations had a duration of about 1 h. Wavelet analysis was used to investigate solar wind as a probable source of the observed ULF pulsations. The time delay compared well with the solar wind travel time estimates and the results suggest a possible link between the solar wind and the observed pulsations. The sudden change in dynamic pressure also proved to be a possible source of the observed ULF pulsations.

  10. Numerical Calculation on Cavitation Pressure Pulsation in Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Weidong Shi

    2014-02-01

    Full Text Available In order to study the internal flow in centrifugal pump when cavitation occurs, numerical calculation of the unsteady flow field in the WP7 automobile centrifugal pump is conducted based on the Navier-Stokes equations with the RNG k – ε turbulence model and Zwart-Gerber-Belamri cavitation model. The distributions of bubble volume fraction and pressure pulsation laws in the pump are analyzed when cavitation occurs. The conclusions are as follows: the bubble volume fraction is larger on the suction side of impeller blade near the inlet edge, which is consistent with the low-pressure region distribution. Bubble volume is determined by the growth rate and collapse rate of every bubble in the bubble group. The cavitation degree changes over time with the impeller rotation and the bubble growth and collapse coexist in the impeller flow channels. The main pulsation results from the cyclic and static coupling between the impeller and the tongue, while the fluctuating amplitude is increased by the cavitation.

  11. Parallel electric fields inferred during a pulsating aurora

    Directory of Open Access Journals (Sweden)

    J. D. Williams

    2006-08-01

    Full Text Available A sounding rocket, equipped to study pulsating aurora launched from Poker Flat, Alaska on 13 March 1997 at 10:20:31 UT, measured electron precipitation over the range ~10 eV to 500 keV covering pitch-angles from 0 to 180°. Data show electrons with energies <1 keV are mostly secondaries produced below the rocket altitude by the higher energy precipitated electrons. We observed nearly equal fluxes of up and down going electrons for energies <1 keV at altitudes from 265 to 380 km. Electron transport simulation results indicate the secondaries produced by the more energetic electrons will have two times higher flux in the upward direction as compared to the downward direction. Our observations of nearly equal fluxes of up and downgoing electrons over a large range of altitudes is consistent with the presence of an electric potential above the rocket that reflects the upgoing electrons back toward the rocket where they are detected as downward going electrons. The strength of the potential is estimated to be 1.5±0.5 kV and its location is no greater than 5000km above the rocket. Finally, the inferred potential drop exists independently of the presence of pulsations.

  12. Study of electric field pulsation in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S; Itoh, K

    2011-01-01

    A model for the experimental results of the periodic oscillation of the electric field, so-called the electric field pulsation, observed in the Compact Helical Device (Fujisawa et al 1998 Phys. Rev. Lett. 81 2256) and the Large Helical Device (Shimizu et al 2010 Plasma Fusion Res. 5 S1015) is presented. A self-generated oscillation of the radial electric field is shown as the simulation result in helical plasmas. The reduction of the anomalous transport diffusivity in the core region is observed due to the strong shear of the radial electric field when the positive electric field is shown in the core region in the periodic oscillation of E r . Two different time scales are found in the self-generated oscillation, which are the transport time scale and the fast time scale at the transition of the radial electric field. This oscillation because of the hysteresis characteristic is attributed to the electric field pulsation observed in helical plasmas. The parameter region of the condition for the self-generated oscillation is derived. It is shown that the multiple solutions of the radial electric field for the ambipolar condition are necessary but not sufficient for obtaining the self-generated oscillation.

  13. Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares

    Science.gov (United States)

    McLaughlin, J. A.; Nakariakov, V. M.; Dominique, M.; Jelínek, P.; Takasao, S.

    2018-02-01

    Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic pulsations (QPPs), to emphasise that they often contain apparent amplitude and period modulation. We review the current understanding of quasi-periodic pulsations in solar and stellar flares. In particular, we focus on the possible physical mechanisms, with an emphasis on the underlying physics that generates the resultant range of periodicities. These physical mechanisms include MHD oscillations, self-oscillatory mechanisms, oscillatory reconnection/reconnection reversal, wave-driven reconnection, two loop coalescence, MHD flow over-stability, the equivalent LCR-contour mechanism, and thermal-dynamical cycles. We also provide a histogram of all QPP events published in the literature at this time. The occurrence of QPPs puts additional constraints on the interpretation and understanding of the fundamental processes operating in flares, e.g. magnetic energy liberation and particle acceleration. Therefore, a full understanding of QPPs is essential in order to work towards an integrated model of solar and stellar flares.

  14. TIDALLY INDUCED PULSATIONS IN KEPLER ECLIPSING BINARY KIC 3230227

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Zhao; Gies, Douglas R. [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States); Fuller, Jim, E-mail: guo@astro.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: jfuller@caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125 (United States)

    2017-01-01

    KIC 3230227 is a short period (P  ≈ 7.0 days) eclipsing binary with a very eccentric orbit ( e  = 0.6). From combined analysis of radial velocities and Kepler light curves, this system is found to be composed of two A-type stars, with masses of M {sub 1} = 1.84 ± 0.18  M {sub ⊙}, M {sub 2} = 1.73 ± 0.17  M {sub ⊙} and radii of R {sub 1} = 2.01 ± 0.09  R {sub ⊙}, R {sub 2} = 1.68 ± 0.08 R {sub ⊙} for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than 10 pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for l  = 2, m  = −2 prograde modes.

  15. Dynamic strain distribution measurement and crack detection of an adhesive-bonded single-lap joint under cyclic loading using embedded FBG

    International Nuclear Information System (INIS)

    Ning, Xiaoguang; Murayama, Hideaki; Kageyama, Kazuro; Wada, Daichi; Kanai, Makoto; Ohsawa, Isamu; Igawa, Hirotaka

    2014-01-01

    In this study, the dynamic strain distribution measurement of an adhesive-bonded single-lap joint was carried out in a cyclic load test using a fiber Bragg grating (FBG) sensor embedded into the adhesive/adherend interface along the overlap length direction. Unidirectional carbon fiber reinforced plastic (CFRP) substrates were bonded by epoxy resin to form the joint, and the FBG sensor was embedded into the surface of one substrate during its curing. The measurement was carried out with a sampling rate of 5 Hz by the sensing system, based on the optical frequency domain reflectometry (OFDR) throughout the test. A finite element analysis (FEA) was performed for the measurement evaluation using a three-dimensional model, which included the embedded FBG sensor. The crack detection method, based on the longitudinal strain distribution measurement, was introduced and performed to estimate the cracks that occurred at the adhesive/adherend interface in the test. (paper)

  16. Immediate Placement and Occlusal Loading of Single-Tooth Restorations on Partially Threaded, Titanium-Tantalum Combined Dental Implants: 1-Year Results.

    Science.gov (United States)

    Peron, Cristian; Romanos, Georgios

    2016-01-01

    Single nonrestorable teeth were atraumatically extracted and hybrid titanium implants with tantalum-based midsections (TM) were placed in fresh extraction sockets. Provisional acrylic crowns were delivered (in occlusion) immediately after surgery. Occlusal contacts were present in the maximal intercuspation but not in the lateral movements of the mandible. Two weeks after placement, the implants were finally restored with screw-retained or cemented lithium disilicate crowns. A total of 25 patients were treated (26 implants). Most implants were placed in maxillary premolar locations and in lower-density bone. Mean crestal bone loss was 0.58 ± 0.34 mm. Implant survival and success rates were 100%, respectively (follow-up: 14.1 ± 1.5 months). Within the limitations of this study, immediate placement and loading of TM implants resulted in predictable clinical, functional, and esthetic outcomes.

  17. Enhancement of the thermal and mechanical properties of polyurethane/polyvinyl chloride blend by loading single walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    A.M. Hezma

    2017-06-01

    Full Text Available Structural, thermal, and mechanical properties of pure blend and nanocomposites based on polyurethane (PU and polyvinyl chloride (PVC doped with low different content of single walled-carbon nanotubes (SWCNTs were studied. The nanocomposites at different concentration were prepared via casting technique. The interaction between PU/PVC and CNTs were examined via FT-IR studies. The changes in the structures of the nanocomposites were examined using X- Ray Diffraction (XRD, and the results indicated that the amorphous domains of nanocomposites increased with increasing SWCNTs content. Transmission electron microscope (TEM observation indicated that SWCNTs surface was wrapped with the polymer with the thermal properties of nanocomposites improved. The mechanical behavior of the nanocomposites was evaluated as a function of SWCNTs content. The main enhancement in tensile properties was observed, e.g., the tensile strength and elastic modulus increased compared with the pure blend, which may be attributed to the interaction and adhesion between CNTs and the polymer matrices due to the hydrogen bonding between carbonyl groups (C=O of polymer blend chains and carboxylic acid (COOH groups of CNTs.

  18. Pressure Hull Analysis under Shock Loading

    Directory of Open Access Journals (Sweden)

    Ya-Jung Lee

    2008-01-01

    Full Text Available The hull of high performance submarines must resist underwater shock loading due to exploding torpedoes or depth bombs. An underwater shock involving an initial shock wave and successive bubble pulsating waves is so complex that a theoretical technique for deriving shock pressure distribution is required for improving simulation efficiency. Complete shock loading is obtained theoretically in this work, and responses of a submarine pressure hull are calculated using ABAQUS USA (Underwater Shock Analysis codes. In the long run, this deflection and stress data will assist in examining the structural arrangement of the submarine pressure hull.

  19. ON THE PULSATIONAL-ORBITAL-PERIOD RELATION OF ECLIPSING BINARIES WITH δ-SCT COMPONENTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X. B.; Luo, C. Q. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Fu, J. N. [Department of Astronomy, Beijing Normal University, Beijing 100875 (China)

    2013-11-01

    We have deduced a theoretical relation between the pulsation and orbital-periods of pulsating stars in close binaries based on their Roche lobe filling. It appears to be of a simple linear form, with the slope as a function of the pulsation constant, the mass ratio, and the filling factor for an individual system. Testing the data of 69 known eclipsing binaries containing δ-Sct-type components yields an empirical slope of 0.020 ± 0.006 for the P{sub pul}-P{sub orb} relation. We have further derived the upper limit of the P{sub pul}/P{sub orb} ratio for the δ-Sct stars in eclipsing binaries with a value of 0.09 ± 0.02. This value could serve as a criterion to distinguish whether or not a pulsator in an eclipsing binary pulsates in the p-mode. Applying the deduced P{sub pul}-P{sub orb} relation, we have computed the dominant pulsation constants for 37 δ-Sct stars in eclipsing systems with definite photometric solutions. These ranged between 0.008 and 0.033 days with a mean value of about 0.014 days, indicating that δ-Sct stars in eclipsing binaries mostly pulsate in the fourth or fifth overtones.

  20. The pulsation modes of the pre-white dwarf PG 1159-035

    OpenAIRE

    Costa, J. E. S.; Riddle, R.

    2008-01-01

    Context. PG 1159-035, a pre-white dwarf with T_(eff) ≃ 140 000 K, is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope (WET) showed a rich frequency spectrum allowing the identification of 122 pulsation modes. Analyzing the periods of pulsation, it is possible to measure the stellar mass, the rotational period and the inclination of the rotation axis, to estim...

  1. Driving and damping mechanisms in hybrid pressure-gravity modes pulsators

    Energy Technology Data Exchange (ETDEWEB)

    Dupret, M A [Observatoire de Paris, LESIA, CNRS UMR 8109, 5 place J. Janssen, 92195 Meudon (France); Miglio, A; Montalban, J; Noels, A [Institut d' Astrophysique et Geophysique, Universite de Liege (Belgium); Grigahcene, A [CRAAG - Algiers Observatory BP 63 Bouzareah 16340, Algiers (Algeria)], E-mail: MA.dupret@obspm.fr

    2008-10-15

    We study the energetic aspects of hybrid pressure-gravity modes pulsations. The case of hybrid {beta} Cephei-SPB pulsators is considered with special attention. In addition to the already known sensitivity of the driving mechanism to the heavy elements mixture (mainly the iron abundance), we show that the characteristics of the propagation and evanescent regions play also a major role, determining the extension of the stable gap in the frequency domain between the unstable low order pressure and high order gravity modes. Finally, we consider the case of hybrid {delta} Sct-{gamma} Dor pulsators.

  2. Behavior of heat transfer in pulsating flow in the channel entrance region

    Science.gov (United States)

    Davletshin, I. A.; Paereliy, A. A.

    2017-09-01

    Convective heat transfer in the entrance region of a plane channel has been studied experimentally. Steady and pulsating air flow regimes have been considered. Heat transfer distributions over the channel wall have been obtained. Non-monotonous behavior of heat transfer coefficient has been revealed at some frequencies and amplitudes of forced flow pulsations. It was accompanied by heat transfer enhancement that was almost double for the local heat transfer coefficients. This may result from generation of vortices in the inlet duct in conditions of flow pulsations.

  3. Observation of quasi-periodic pulsations in the solar flare SF 900610

    DEFF Research Database (Denmark)

    Terekhov, O.V.; Shevchenko, A.V.; Kuz'min, A.G.

    2002-01-01

    A quasi-periodic component was found at the maximum of the X-ray light curve for the June 10, 1990 solar flare detected by the Granat observatory. The pulsation period was 143.2 +/- 0.8 s. The intensity of the pulsing component is not constant; the maximum amplitude of the pulsations is similar to5......% of the total flare intensity. An analysis of the data showed the characteristic size of the magnetic loop responsible for these pulsations to be similar to(1-3) x 10(10) cm....

  4. The propagation of pressure pulsations in the primary circuit of power plant A1

    International Nuclear Information System (INIS)

    Pecinka, L.

    1976-01-01

    A classification is made of the exciting forces of pressure pulsations in the primary coolant circuit with forced coolant circulation. A mathematical model is constructed of the propagation of pressure pulsations in the system and examples of measurements are given. The measurement methods used and the methods for the generalization of obtained data are assessed. The methods and results of the measurements of hydrodynamic pressure pulsations in a closed primary circuit with forced coolant circulation of the A-1 nuclear power plant are given. (F.M.)

  5. The pulsation-rotation interaction: Greatest hits and the B-side

    Science.gov (United States)

    Townsend, Rich

    2014-02-01

    It has long been known that rotation can have an appreciable impact on stellar pulsation - by modifying the usual p and g modes found in the non-rotating case, and by introducing new classes of modes. However, it's only relatively recently that advances in numerical simulations and complementary theoretical treatments have enabled us to model these phenomena in any great detail. In this talk I'll review highlights in this area (the `Greatest Hits'), before considering the flip side (or the `B-side', for those of us old enough to remember vinyl records) of the pulsation-rotation interaction: how pulsation can itself influence internal rotation profiles.

  6. A comparison of Pc magnetic pulsations on the ground and at synchronous orbit

    International Nuclear Information System (INIS)

    Veroe, J.; Hollo, L.

    1983-01-01

    The paper presents a summary of results on the comparison of pulsations data from the satellite ATS 6 and the surface station Nagycenk for a year in 1973-74. In spite of the difference in position and L-value, strong similarities were observed, and even a part of the existing differences could be explained in terms of the afternoon-activity unobservable on ground. Diurnal variation of short period pulsation amplitudes were detected. The dependence of observed pulsation characteristics on solar wind velocity are discussed. (D.Gy.)

  7. Secular Pulsation Amplitude Variations in the Subdwarf-B Star Component of the V4640 Sgr Binary

    Science.gov (United States)

    Lynas-Gray, A. E.

    2013-12-01

    V4640 Sgr (EC 20117-4014) is understood to be a long-period binary consisting of a V361 Hya type pulsating subdwarf-B star and a F5 V star. Observations obtained before 2010 show the amplitude of the dominant power spectrum peak (7.28 mHz) to be constant when data from all nights in each season are combined and analysed as a single time-series. Because of the need to constrain mass-transfer scenarios in binaries like V4640 Sgr when the subdwarf-B star progenitor was at or near the Helium Flash, this object was selected for further photometric monitoring with the intention of using a changing light travel-time to improve the orbit determination. An analysis of 2011 August, and existing 2001 July, time series show the 7.28 mHz frequency to have secular nightly amplitude changes. Comparing with similar pulsation amplitude changes in V541 Hya and KIC 010139564 suggested these are a consequence of unresolved rotation splitting, with two or more split components beating against each other. Modelling for confirmation, and assessment of any associated frequency changes, would be needed before any refinement of the light travel-time orbit determination.

  8. Zinc electrodeposition from alkaline zincate solution by pulsating overpotentials

    Directory of Open Access Journals (Sweden)

    MILOS V. SIMICIC

    2000-09-01

    Full Text Available It is well known that smooth zinc deposits cannot be obtained from alkaline zincate using constant overpotential and current rate. During prolonged metal deposition, spongy and dendritic deposits are formed. It has been shown that the deposits are less agglomerated in the case of square-wave pulsating overpotentials regime than the ones obtained in case of constant overpotential regime. This is explained in a semiquantitative way by two phenomena: selective anodic dissolution during overpotentials “off” period and decreasing diffusion control. These effects is more pronounced at higher pause-to-pulse ratio. Increasing the pause-to-pulse ratio causes a reduction of the ratio between diffusion and activation overpotential, resulting in a more compact deposit. Confirmation of the proposed semiquantitative mathematical model was obtained by zinc electrodeposition onto a copper wire from a 0.1 M zincate solution in 1.0 M KOH at room temperature.

  9. Numerical investigation on pulsating heat pipes with nitrogen or hydrogen

    Science.gov (United States)

    Y Han, D.; Sun, X.; Gan, Z. H.; Y Luo, R.; Pfotenhauer, J. M.; Jiao, B.

    2017-12-01

    With flexible structure and excellent performance, pulsating heat pipes (PHP) are regarded as a great solution to distribute cooling power for cryocoolers. The experiments on PHPs with cryogenic fluids have been carried out, indicating their efficient performances in cryogenics. There are large differences in physical properties between the fluids at room and cryogenic temperature, resulting in their different heat transfer and oscillation characteristics. Up to now, the numerical investigations on cryogenic fluids have rarely been carried out. In this paper, the model of the closed-loop PHP with multiple liquid slugs and vapor plugs is performed with nitrogen and hydrogen as working fluids, respectively. The effects of heating wall temperature on the performance of close-looped PHPs are investigated and compared with that of water PHP.

  10. Pulsating jet-like structures in magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, V. P. [A. M. Obukhov Institute of Atmospheric Physics RAS, 109017 Moscow (Russian Federation); Pavlov, V. I. [UFR des Mathématiques Pures et Appliquées, Univ. Lille, CNRS FRE 3723 - LML, F-59000 Lille (France)

    2016-08-15

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as “radio pulsars.” The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  11. Pulsations of microwave flaring emission at low and high frequencies

    Science.gov (United States)

    Reznikova, V. E.; Melnikov, V. F.; Su, Y.; Huang, G.

    2007-07-01

    A wavelet analysis of the flare-intensity variations has been carried out for a solar flare observed with the Nobeyama Radioheliograph at 17 and 34 GHz and the spectrometer of Purple Mountain Observatory at 4.5-7.5 GHz. The signals contain a well-pronounced periodicity with a period of P = 14-17 s and stable, coherent behavior at frequencies higher and lower than the peak frequency. We simulated the modulation of the gyrosynchrotron emission by fast sausage magnetoacoustic oscillations for the cases of low and high plasma density in the radio source. The synchronism of the pulsations at high and low frequencies can be realized only in the case of high plasma density, when the low-frequency turnover of the microwave spectrum is due to the Razin effect, not self-absorption.

  12. A 'one in a million' case of pulsating thoracoabdominal mass.

    LENUS (Irish Health Repository)

    Tan, Lay Ong

    2012-11-01

    Ectopia cordis is a rare congenital malformation in which the heart is located partially or totally outside the thoracic cavity. It comprises 0.1% of congenital heart diseases. The authors present a case of a male baby born at term by emergency caesarean section due to prolonged fetal bradycardia, who was noted to have a large pulsating mass in the thoracoabdominal area. In view of lower thoracolumbar abdominal defect, ectopic placement of the umbilicus, deficiency of the diaphragmatic pericardium, deficiency of anterior diaphragm and intracardiac abnormalities, a diagnosis of ectopia cordis-Pentalogy of Cantrell was made. He was transferred to a tertiary centre and required oxygen supplement initially. He was sent home after 1 week, on propanolol, with weekly oxygen saturation checks. He is awaiting further surgical intervention pending the required weight gain.

  13. Asteroseismology of pulsating DA white dwarfs with fully evolutionary models

    Directory of Open Access Journals (Sweden)

    Althaus L.G.

    2013-03-01

    Full Text Available We present a new approach for asteroseismology of DA white dwarfs that consists in the employment of a large set of non-static, physically sound, fully evolutionary models representative of these stars. We already have applied this approach with success to pulsating PG1159 stars (GW Vir variables. Our white dwarf models, which cover a wide range of stellar masses, effective temperatures, and envelope thicknesses, are the result of fully evolutionary computations that take into account the complete history of the progenitor stars from the ZAMS. In particular, the models are characterized by self-consistent chemical structures from the centre to the surface, a crucial aspect of white dwarf asteroseismology. We apply this approach to an ensemble of 44 bright DAV (ZZ Ceti stars.

  14. The Immediate Effects of Conventional Physical Therapy on the Knee Joint Load in Subjects with Moderate Knee Osteoarthritis; A Preliminary Single Blinded Randomized Control Trial

    Directory of Open Access Journals (Sweden)

    Leila Fattahi

    2015-12-01

    Full Text Available Background: Subjects with knee osteoarthritis typically have higher knee adduction moment. Current research efforts are mainly focused on therapeutic procedures that potentially may modify disease progression. This preliminary study was designed as a single blind (examiner randomized control trial to investigate the impact of conventional physical therapy on pain, and knee joint load in subjects with moderate knee osteoarthritis. Methods: Twelve participants diagnosed with moderate knee OA were randomly assigned into control and intervention groups. Three-dimensional knee kinematic and kinetic data were recorded during the gait before and after 10 sessions of conventional physical therapy. In addition, pain intensity was evaluated by visual analog scale and pain subscale of KOOS questionnaire. The control group did not receive any intervention during the same period. Gait parameters were analyzed within and between groups using nonparametric tests. Results: There was a significant difference between groups in baseline KOOS-pain Score and ML knee force (P=0.048 and P=0.01. Immediately after ten sessions of physical therapy the initial (first peak of knee adduction moment was significantly (P=0.03 lower than that of the control group while the first and second peak of knee AP velocity were significantly (P=0.02, P=0.01 respectively higher. In the intervention group, the second peaks of vertical and anteroposterior (AP knee forces were strongly correlated with the pretest KOOS-pain Score (r=0.99 and r=0.98, P<0.001. Therefore a multivariate general linear model was adopted with adjustment to baseline KOOS-pain. By this adjustment, 51% alleviation of VAS pain score and 81% decrement of first peak of knee adduction moment in comparison to control group was statistically significant (P=0.02, P=0.03 respectively. Conclusion: It seems that ten sessions of conventional physical therapy may modify knee joint load in subjects with moderate knee

  15. Influence of Laser-Lok surface on immediate functional loading of implants in single-tooth replacement: a 2-year prospective clinical study.

    Science.gov (United States)

    Farronato, Davide; Mangano, Francesco; Briguglio, Francesco; Iorio-Siciliano, Vincenzo; Riccitiello, Francesco; Guarnieri, Renzo

    2014-01-01

    The purpose of this study was to evaluate the influence of a Laser-Lok microtexturing surface on clinical attachment level and crestal bone remodeling around immediately functionally loaded implants in single-tooth replacement. Seventy-seven patients were included in a prospective, randomized study and divided into two groups. Group 1 (control) consisted of non-Laser-Lok type implants (n = 39), while in group 2 (test), Laser-Lok type implants were used (n = 39). Crestal bone loss (CBL) and clinical parameters including clinical attachment level (CAL), Plaque Index (PI), and bleeding on probing were recorded at baseline examinations and at 6, 12, and 24 months after loading with the final restoration. One implant was lost in the control group and one in the test group, giving a total survival rate of 96.1% after 2 years. PI and BOP outcomes were similar for both implant types without statistical differences. A mean CAL loss of 1.10 ± 0.51 mm was observed during the first 2 years in group 1, while the mean CAL loss observed in group 2 was 0.56 ± 0.33 mm. Radiographically, group 1 implants showed a mean crestal bone loss of 1.07 ± 0.30 mm compared with 0.49 ± 0.34 mm for group 2. The type of implant did not influence the survival rate, whereas Laser-Lok implants resulted in greater CAL and in shallower radiographic peri-implant CBL than non-Laser-Lok implants.

  16. Pulsation, Mass Loss and the Upper Mass Limit

    Science.gov (United States)

    Klapp, J.; Corona-Galindo, M. G.

    1990-11-01

    RESUMEN. La existencia de estrellas con masas en exceso de 100 M0 ha sido cuestionada por mucho tiempo. Lfmites superiores para la masa de 100 M0 han sido obtenidos de teorfas de pulsaci6n y formaci6n estelar. En este trabajo nosotros primero investigamos la estabilidad radial de estrellas masivas utilizando la aproximaci6n clasica cuasiadiabatica de Ledoux, la aproximaci6n cuasiadiabatica de Castor y un calculo completamente no-adiabatico. Hemos encontrado que los tres metodos de calculo dan resultados similares siempre y cuando una pequefia regi6n de las capas externas de la estrella sea despreciada para la aproximaci6n clasica. La masa crftica para estabilidad de estrellas masivas ha sido encontrada en acuerdo a trabajos anteriores. Explicamos Ia discrepancia entre este y trabajos anteriores por uno de los autores. Discunmos calculos no-lineales y perdida de masa con respecto a) lfmite superior de masa. The existence of stars with masses in excess of 100 M0 has been questioned for a very long time. Upper mass limits of 100 Me have been obtained from pulsation and star formation theories. In this work we first investigate the radial stability of massive stars using the classical Ledoux's quasiadiabatic approximation. the Castor quasiadiabatic approximation and a fully nonadiabatic calculation. We have found that the three methods of calculation give similar results provided that a small region in outer layers of the star be neglected for the classical approximation. The critical mass for stability of massive stars is found to be in agreement with previous work. We explain the reason for the discrepancy between this and previous work by one of the authors. We discuss non-linear calculations and mass loss with regard to the upper mass limit. Key words: STARS-MASS FUNCTION - STARS-MASS LOSS - STARS-PULSATION

  17. Cerebrospinal fluid pulsation amplitude and its quantitative relationship to cerebral blood flow pulsations: a phase-contrast MR flow imaging study

    International Nuclear Information System (INIS)

    Bhadelia, R.A.; Bogdan, A.R.; Kaplan, R.F.; Wolpert, S.M.

    1997-01-01

    Our purpose in this investigation was to explain the heterogeneity in the cerebrospinal fluid (CSF) flow pulsation amplitudes. To this end, we determined the contributions of the cerebral arterial and jugular venous flow pulsations to the amplitude of the CSF pulsation. We examined 21 healthy subjects by cine phase-contrast MRI at the C2-3 disc level to demonstrate the CSF and vascular flows as waveforms. Multiple regression analysis was performed to calculate the contributions of (a) the arterial and venous waveform amplitudes and (b) the delay between the maximum systolic slopes of the arterial and venous waveforms (AV delay), in order to predict the amplitude of the CSF waveform. The contribution of the arterial waveform amplitude was positive (r = 0.61; p 0.003) to the CSF waveform amplitude and that of the venous waveform amplitude was negative (r = -0.50; p = 0.006). Both in combination accounted for 56 % of the variance in predicting the CSF waveform amplitude (p < 0.0006). The contribution of AV delay was not significant. The results show that the variance in the CSF flow pulsation amplitudes can be explained by concurrent evaluation of the CSF and vascular flows. Improvement in the techniques, and controlled experiments, may allow use of CSF flow pulsation amplitudes for clinical applications in the non-invasive assessment of intracranial dynamics by MRI. (orig.). With 3 figs., 2 tabs

  18. A systematic search for new X-ray pulsators in ROSAT fields

    Science.gov (United States)

    Israel, G. L.

    1996-10-01

    possible frequency interval; the other to detect periodic signals of reduced coherence. This thesis represents the first detailed timing analysis study of a very large number of X-ray sources. So far the automated search for coherent pulsations was performed twice over the whole sample: the first time by preserving the original Fourier resolution while the second extending the search to the maximum possible Nyquist frequency (depending on the total source photon). About 500 sources were found to possess power spectrum peaks above the detection threshold (besides the spurious peaks) but so far, only for about 10 of them a detailed analysis was carried out to confirm the presence of a reliable periodic signal. A search in the same light curves sample but at different energy intervals is in progress. Among the detected peaks in the database, there is a small number of especially interesting pulsator candidates, that were extensively analysed. This led to very significant results. This is the case of the strong 13s pulsations discovered (15sigma confidence level) in the X-ray flux of HD49798 / 1WGA J0648.0-4418 (Israel et al. 1995, 1996a), a 1.55 day single-component spectroscopic binary containing a hydrogen depleted subdwarf O6 star. The source X-ray spectrum is extremely soft, with an unabsorbed 0.1-2 keV luminosity of a few 10^32 erg/s (distance of 650 pc). A higher luminosity might be hidden in the EUV. These results indicate that the companion of HD49798 is a compact star: an accreting degenerate star, a white dwarf or, more likely, a neutron star. In either case HD49798 corresponds to a previously unobserved evolutionary stage of a massive binary system, after common envelope and spiral-in. If the 13s pulsations arise directly from the rotation of the degenerate star, they would be coherent enough to make HD 49798 a ``double spectroscopic" binary; in this case the system would hold a great potential for accurate mass measurement. A further important result is the

  19. K2 Observations of the New Pulsating White Dwarf EPIC 245988146

    Science.gov (United States)

    Vasquez Soto, Alan; Barlow, Brad; Hermes, JJ

    2018-01-01

    In 2015 we discovered low-amplitude pulsations in the white dwarf EPIC 245988146 using ground-based observations with the CTIO 0.9-m telescope. Three months of follow-up, short cadence photometry obtained with K2 reveals a much richer pulsation spectrum than could be achieved from the ground. We have identified several independent pulsation modes, a large number of combination frequencies, and even a few multiplets indicative of stellar rotation. Here we present our preliminary analysis of the K2 photometry, along with the Fourier transform (FT) of the full light curve and a sliding FT to highlight changes in the pulsation spectrum over the 77-day observation period.

  20. Recent Advances in the Theoretical Modeling of Pulsating Low-mass He-core White Dwarfs

    Science.gov (United States)

    Córsico, A. H.; Althaus, L. G.; Calcaferro, L. M.; Serenelli, A. M.; Kepler, S. O.; Jeffery, C. S.

    2017-03-01

    Many extremely low-mass (ELM) white-dwarf (WD) stars are currently being found in the field of the Milky Way. Some of these stars exhibit long-period nonradial g-mode pulsations, and constitute the class of ELMV pulsating WDs. In addition, several low-mass pre-WDs, which could be precursors of ELM WDs, have been observed to show short-period photometric variations likely due to nonradial p modes and radial modes. They could constitute a new class of pulsating low-mass pre-WD stars, the pre-ELMV stars. Here, we present the recent results of a thorough theoretical study of the nonadiabatic pulsation properties of low-mass He-core WDs and pre-WDs on the basis of fully evolutionary models representative of these stars.

  1. The Nainital Cape Survey Project : A Search for Pulsation in Chemically Peculiar Stars

    Science.gov (United States)

    Chakradhari, Nand Kumar; Joshi, Santosh

    2018-04-01

    The Nainital-Cape Survey is a dedicated search programme initiated in 1999 in the coordination of astronomers from SAAO South Africa, ARIES Nainital and ISRO Bangalore. Over the last 17 years a total of 345 chemically peculiar stars were monitored for photometric variability, making it one of the longest ground-based survey to search for pulsation in chemically peculiar stars in terms of both time span and sample size. Under this survey, we discovered rapid pulsation in the Ap star HD12098 while δ Scuti-type pulsations were detected in seven Am stars. Those stars in which pulsations were not detected have also been tabulated along with their detailed astrophysical parameters for further investigation.

  2. Reduction of a Double Supply Frequency Pressure Pulsation in an Electro-Magnetic Pump

    International Nuclear Information System (INIS)

    Seong, Seung-Hwan; Park, Rae-Young; Lee, Tae-Ho; Kim, Seong-O

    2007-01-01

    Fast breeder reactors using sodium coolant have adopted the AC induction electro-magnetic (EM) pump as a coolant pump for a liquid metal flow. The EM pumps have some disadvantages such as a double supply frequency (DSF) pressure pulsation and so on. The DSF pressure pulsation occurs in the induction EM pump, when an alternating current is supplied to the coils. The magnetic field produced by the coils reacts with the alternating current being passed through the sodium, and then the pressure developed pulsates at twice the input frequency. The DSF pressure pulsation is dominantly affected by the disturbances of the electromagnetic force near the stator or core ends. The disturbance of the electromagnetic force can be derived the Lenz's Law which means that the opposite forces are generated when the magnetic field abruptly changed by the liquid metal flows near the stator ends. This phenomenon is called as the end effect

  3. Effect of the August 11, 1999 total solar eclipse on geomagnetic pulsations

    Czech Academy of Sciences Publication Activity Database

    Pal, B.; Heilig, B.; Zieger, B.; Szendröi, J.; Verö, J.; Lühr, H.; Yumoto, K.; Tanaka, Y.; Střeštík, Jaroslav

    2007-01-01

    Roč. 42, č. 1 (2007), s. 23-58 ISSN 1217-8977 Institutional research plan: CEZ:AV0Z30120515 Keywords : field line resonance * geomagnetic pulsations * solar eclipse Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  4. Optimisation of single-phase dry-thermophilic anaerobic digestion under high organic loading rates of industrial municipal solid waste: population dynamics.

    Science.gov (United States)

    Zahedi, S; Sales, D; Romero, L I; Solera, R

    2013-10-01

    Different high feed organic loading rates (OLRs) (from 5.7 g to 46.0 g TVS/l/d) or hydraulic retention times (HRTs) (from 15 d to 2 d) in single-phase dry-thermophilic anaerobic digestion (AD) of organic fraction municipal solid waste (OFMSW) were investigated. The specific gas production (SGP) values (0.25-0.53 m(3)/kg TVS) and the percentages of Eubacteria, Archaea, H2-utilising methanogens (HUMs) and acetate-utilising methanogens (AUMs) were stable within the ranges 80.2-91.1%, 12.4-18.5%, 4.4-9.8% and 5.5-10.9%, respectively. A HUM/AUM ratio greater than 0.7 seems to be necessary to maintain very low partial pressures of H2 required for dry AD process. Increasing OLR resulted in an increase in all the populations, except for propionate-utilising acetogens (PUAs). Optimal conditions were obtained at 3d HRT (OLR=30.7 g TVS/l/d), which is lower than the doubling time of acetogens and methanogens. The methane production (MP) was clearly higher than those reported in AD of OFMSW. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Photothermal-triggered control of sub-cellular drug accumulation using doxorubicin-loaded single-walled carbon nanotubes for the effective killing of human breast cancer cells

    Science.gov (United States)

    Oh, Yunok; Jin, Jun-O.; Oh, Junghwan

    2017-03-01

    Single-walled carbon nanotubes (SWNTs) are often the subject of investigation as effective photothermal therapy (PTT) agents owing to their unique strong optical absorption. Doxorubicin (DOX)-loaded SWNTs (SWNTs-DOX) can be used as an efficient therapeutic agent for combined near infrared (NIR) cancer photothermal and chemotherapy. However, SWNTs-DOX-mediated induction of cancer cell death has not been fully investigated, particularly the reaction of DOX inside cancer cells by PTT. In this study, we examined how the SWNTs-DOX promoted effective MDA-MB-231 cell death compared to DOX and PTT alone. We successfully synthesized the SWNTs-DOX. The SWNTs-DOX exhibited a slow DOX release, which was accelerated by NIR irradiation. Furthermore, DOX released from the SWNTs-DOX accumulated inside the cells at high concentration and effectively localized into the MDA-MB-231 cell nucleus. A combination of SWNTs-DOX and PTT promoted an effective MDA-MB-231 cell death by mitochondrial disruption and ROS generation. Thus, SWNTs-DOX can be utilized as an excellent anticancer agent for early breast cancer treatment.

  6. Outbursts from Cool Pulsating White Dwarfs in Kepler and K2

    Science.gov (United States)

    Bell, Keaton J.; Hermes, J. J.; Montgomery, Michael H.; Winget, Donald E.

    2017-01-01

    Data from the Kepler and K2 missions have captured the signatures of a new pulsation-related phenomenon in hydrogen atmosphere white dwarfs. Some pulsating white dwarfs within 500 K of the empirical cool edge of the ZZ Ceti instability strip exhibit outburst-like brightness enhancements of up to 15% that last many hours and recur irregularly on timescales on days. In this thesis talk, I summarize the observational characteristics of this new outbursting class of ZZ Ceti.

  7. Attenuation of Vane-Rotor Shock Interactions with Pulsating Coolant Flows

    Science.gov (United States)

    2012-03-01

    consists on, pulsating coolant blowing through the trailing edge of the airfoils . This paper presents an unprecedented experimental and numerical...A transonic turbine airfoil was experimentally and numerically tested to resolve the effects of pulsating cooling The model was tested at four Mach...interactions are one of the major sources of losses in supersonic airfoils . Additionally, vane shocks cause large pressure fluctuations that may result in

  8. Optical pulsations from 4U 0900--40: Do they exist

    International Nuclear Information System (INIS)

    Nelson, J.; Middleditch, J.; Cordova, F.

    1979-01-01

    A search for optical pulsations from 4U 0900--40 (HD 77581) was made in 1977--1978 using Hβ interference filters. No pulsations were detected above 10 -3 of the observed flux. This contrasts with Steiner's detection of pulsatons at the 2% level. Ariel 5 data covering both our observations and Steiner's show that X-ray variability does not support this decrepancy

  9. The pulsation mode and period-luminosity relationship of cool variables in globular clusters

    International Nuclear Information System (INIS)

    Whitelock, P.A.

    1986-01-01

    The period-luminosity-temperature relationship for globular cluster red and yellow variables is examined. The results suggest that the higher temperature, more metal-deficient cluster variables pulsate in the fundamental mode, while the lower temperature more metal-rich variables pulsate in the first overtone. On the assumption that this is correct, a relationship between fundamental period and bolometric magnitude is derived for cluster variables with observed periods of between 1 and 300 days. (author)

  10. Photometric Evidence of Changes in Pulsation Characteristics of Hot Subdwarf B Stars

    Science.gov (United States)

    Raghavan, Arjun

    2014-01-01

    Rapidly pulsating subdwarf B stars (sdBVR stars) are the fastest pulsating star class in the Universe, exhibiting pulsations in light energy ranging from 80 to 600 seconds. These rare stars are especially important because the multiple pulsation frequencies found in them provide astronomers with the remarkable opportunity to research the internal structures of stars through asteroseismology. Until now, only about 70 sdBVR’s have been identified and a number of these have never been re-observed after their discoveries to look for any differences in their pulsation characteristics. This study thoroughly examines changes in the pulsation characteristics of 8 of the 70 sdBVR stars. Thousands of images were processed, Fourier transforms of light curves were calculated, and multiple noise-accounting procedures were undertaken. After analysis, it was found that the observational evidence substantiated the theory that amplitude changes occur in most sdBVR’s, with 6 out of the 8 stars showing significant amplitude changes with time. Thus, a current compilation of changes on a variety of timescales, essential for further research, was documented in this study.

  11. Analysis of Pressure Pulsation Induced by Rotor-Stator Interaction in Nuclear Reactor Coolant Pump

    Directory of Open Access Journals (Sweden)

    Xu Zhang

    2017-01-01

    Full Text Available The internal flow of reactor coolant pump (RCP is much more complex than the flow of a general mixed-flow pump due to high temperature, high pressure, and large flow rate. The pressure pulsation that is induced by rotor-stator interaction (RSI has significant effects on the performance of pump; therefore, it is necessary to figure out the distribution and propagation characteristics of pressure pulsation in the pump. The study uses CFD method to calculate the behavior of the flow. Results show that the amplitudes of pressure pulsation get the maximum between the rotor and stator, and the dissipation rate of pressure pulsation in impellers passage is larger than that in guide vanes passage. The behavior is associated with the frequency of pressure wave in different regions. The flow rate distribution is influenced by the operating conditions. The study finds that, at nominal flow, the flow rate distribution in guide vanes is relatively uniform and the pressure pulsation amplitude is the smallest. Besides, the vortex shedding or backflow from the impeller blade exit has the same frequency as pressure pulsation but there are phase differences, and it has been confirmed that the absolute value of phase differences reflects the vorticity intensity.

  12. Pseudo-field line resonances in ground Pc5 pulsation events

    Directory of Open Access Journals (Sweden)

    D. V. Sarafopoulos

    2005-02-01

    Full Text Available In this work we study four representative cases of Pc5 ground pulsation events with discrete and remarkably stable frequencies extended at least in a high-latitude range of ~20°; a feature that erroneously gives the impression for an oscillation mode with "one resonant field line". Additionally, the presented events show characteristic changes in polarization sense, for a meridian chain of stations from the IMAGE array, and maximize their amplitude at or close to the supposed resonant magnetic field shell, much like the typical FLR. Nevertheless, they are not authentic FLRs, but pseudo-FLRs, as they are called. These structures are produced by repetitive and tilted twin-vortex structures caused by magnetopause surface waves, which are probably imposed by solar wind pressure waves. The latter is confirmed with in-situ measurements obtained by the Cluster satellites, as well as the Geotail, Wind, ACE, and LANL 1994-084 satellites. This research effort is largely based on two recent works: first, Sarafopoulos (2004a has observationally established that a solar wind pressure pulse (stepwise pressure variation produces a twin-vortex (single vortex current system over the ionosphere; second, Sarafopoulos (2004b has studied ground events with characteristic dispersive latitude-dependent structures and showed that these are associated with twin-vortex ionosphere current systems. In this work, we show that each pseudo-FLR event is associated with successive and tilted large-scale twin-vortex current systems corresponding to a magnetopause surface wave with wavelength 10-20RE. We infer that between an authentic FLR, which is a spatially localized structure with an extent 0.5RE in the magnetospheric equatorial plane, and the magnetopause surface wavelength, there is a scale factor of 20-40. A chief observational finding, in this work, is that there are Pc5 ground pulsation events showing two gradual and latitude

  13. A 59-year-old woman with visible precordial pulsations.

    Science.gov (United States)

    Moss, Alastair J; Pessotto, Renzo; Flapan, Andrew D

    2018-02-01

    CLINICAL INTRODUCTION: A retired 59-year-old woman presented to the cardiology clinic concerned with cardiac pulsations that were visible on her chest wall. These were not associated with dyspnoea, syncope or chest discomfort.Of note, 8 years previously, she complained of recurrent nocturnal diaphoresis and 5 kg weight loss. Blood sampling at that time revealed a microcytic anaemia, reactive thrombocytosis and raised inflammatory markers (erythrocyte sedimentation rate 99 mm/hour, C-reactive protein 161 mg/L). Following an episode of transient diplopia, ophthalmoscopy demonstrated a cotton wool spot in the left inferotemporal retinal arcade. She commenced a 2-year tapering course of 1 mg/kg prednisolone.On examination, she had a lean physique with a supine blood pressure of 162/60 mm Hg and palpable Corrigan's pulse. She had a prominent apical pulsation and a loud early diastolic murmur was present at the left sternal edge radiating to the apex. Echocardiography showed severe central aortic regurgitation and a dilated aortic root (see online supplementary figure 1). Cardiac CT was performed to clarify the diagnosis (figure 1).DC1SP110.1136/heartjnl-2017-312193.supp1Supplementary file 1 heartjnl;104/3/273/F1F1F1Figure 1Contrast-enhanced CT of the thorax at index presentation (A) and 6 months (B). Prospective ECG-gated cardiac CT angiogram (75% R-R interval) performed at 8 years from index presentation (C) with a stretched multiplanar reconstruction of the aortic annulus, aortic root and thoracic aorta (D). Which of the following diagnoses best explains this presentation?Ankylosing spondylitisTakayasu arteritisSalmonellosisIgG4-related aortitisGiant cell aortitis. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  14. Immediate loading of bimaxillary total fixed prostheses supported by five flapless-placed implants with machined surfaces: A 6-month follow-up prospective single cohort study.

    Science.gov (United States)

    Cannizzaro, Gioacchino; Felice, Pietro; Loi, Ignazio; Viola, Paolo; Ferri, Vittorio; Leone, Michele; Collivasone, Dario; Esposito, Marco

    2016-01-01

    To evaluate the clinical outcome of fully edentulous patients rehabilitated with immediately loaded bimaxillary screw-retained metal-resin prostheses supported by five implants placed flapless: two in the mandible and three in the maxillae. Twenty-five consecutively treated patients were recruited. To be immediately loaded, implants had to be inserted with a minimum torque of 80 Ncm. Outcome measures were prosthesis and implant failures, and complications. Six months after loading no patients dropped out and no prosthesis or implant failed. Two maxillary prostheses were loaded early at 8 weeks because implants were inserted with a torque inferior to 45 Ncm. Three complications occurred in two patients but they were all successfully treated. Six months after loading, immediately loaded bimaxillary cross-arch prostheses can be supported by only two mandibular and three maxillary flapless-placed dental implants. Longer follow-ups of approximately 10 years are needed to understand the prognosis of this treatment modality.

  15. KIC 4552982: outbursts and pulsations in the longest-ever pseudo-continuous light curve of a ZZ Ceti

    Directory of Open Access Journals (Sweden)

    Bell K. J.

    2015-01-01

    Full Text Available KIC 4552982 was the first ZZ Ceti (hydrogen-atmosphere pulsating white dwarf identified to lie in the Kepler field, resulting in the longest pseudo-continuous light curve ever obtained for this type of variable star. In addition to the pulsations, this light curve exhibits stochastic episodes of brightness enhancement unlike any previously studied white dwarf phenomenon. We briefly highlight the basic outburst and pulsation properties in these proceedings.

  16. Self-organized compound pattern and pulsation of dissipative solitons in a passively mode-locked fiber laser

    Science.gov (United States)

    Wang, Zhenhong; Wang, Zhi; Liu, Yange; He, Ruijing; Zhao, Jian; Wang, Guangdou; Yang, Guang

    2018-02-01

    We experimentally observe soliton self-organization and pulsation in a passively mode-locked fiber laser. The optomechanical interaction in the optical fiber is key to the formation of equidistant soliton bunches. These solitons simultaneously undergo a pulsation process with a period corresponding to tens of the cavity round trip time. Using the dispersive Fourier transformation technique, we find that the Kelly sidebands in the shot-to-shot spectra appear periodically, synchronizing with the pulsation.

  17. Resistance Training with Single vs. Multi-joint Exercises at Equal Total Load Volume: Effects on Body Composition, Cardiorespiratory Fitness, and Muscle Strength

    Science.gov (United States)

    Paoli, Antonio; Gentil, Paulo; Moro, Tatiana; Marcolin, Giuseppe; Bianco, Antonino

    2017-01-01

    The present study aimed to compare the effects of equal-volume resistance training performed with single-joint (SJ) or multi-joint exercises (MJ) on VO2max, muscle strength and body composition in physically active males. Thirty-six participants were divided in two groups: SJ group (n = 18, 182.1 ± 5.2, 80.03 ± 2.78 kg, 23.5 ± 2.7 years) exercised with only SJ exercises (e.g., dumbbell fly, knee extension, etc.) and MJ group (n = 18, 185.3 ± 3.6 cm, 80.69 ± 2.98 kg, 25.5 ± 3.8 years) with only MJ exercises (e.g., bench press, squat, etc.). The total work volume (repetitions × sets × load) was equated between groups. Training was performed three times a week for 8 weeks. Before and after the training period, participants were tested for VO2max, body composition, 1 RM on the bench press, knee extension and squat. Analysis of covariance (ANCOVA) was used to compare post training values between groups, using baseline values as covariates. According to the results, both groups decreased body fat and increased fat free mass with no difference between them. Whilst both groups significantly increased cardiorespiratory fitness and maximal strength, the improvements in MJ group were higher than for SJ in VO2max (5.1 and 12.5% for SJ and MJ), bench press 1 RM (8.1 and 10.9% for SJ and MJ), knee extension 1 RM (12.4 and 18.9% for SJ and MJ) and squat 1 RM (8.3 and 13.8% for SJ and MJ). In conclusion, when total work volume was equated, RT programs involving MJ exercises appear to be more efficient for improving muscle strength and maximal oxygen consumption than programs involving SJ exercises, but no differences were found for body composition. PMID:29312007

  18. Numerical simulation of nonlinear dynamics of 1D pulsating detonations

    Science.gov (United States)

    Borisov, S. P.; Kudryavtsev, A. N.

    2017-10-01

    The development of 1D instability of a detonation wave is numerically simulated for a two-stage chemical model. The shock-fitting approach is employed to track the leading detonation front. In order to determine its motion, the equation for the acceleration of the shock wave derived from the Rankine-Hugoniot conditions and the characteristic relations is integrated along with the reactive Euler equations. The fifth-order WENO scheme is used, time stepping is performed with the four-stage Runge-Kutta-Gill method. It is shown that in a certain range of parameters of the problem (the degree of overdrive f, the dissociation energy Ed and the activation energy Ea ), the Zeldovich-Neumann-Döring stationary solution is unstable with respect to 1D disturbances. The evolution of disturbances at later nonlinear stages is studied. Nonlinear saturation of the growth of disturbances leads to the formation of a stable limit cycle. When changing the parameters of the problem, the period doubling bifurcation can occur leading to the appearance of pulsations with two different maxima of the amplitude.

  19. On the Propagation of Gravitation from a Pulsating Source

    Directory of Open Access Journals (Sweden)

    Stavroulakis N.

    2007-04-01

    Full Text Available According to an idea underlying the classical relativity, a pulsating (or simply expanding or simply contracting spherical source does not generate an external dynamical (i.e. non-stationary gravitational field. The relativists believe that this idea is well based on account of the so-called Birkhoff’s theorem, which, contrary to the fundamental principles of general relativity, states that the external gravitational field of a non-stationary spherical mass is necessarily static. However, as shown in several papers [2, 3, 4, 7, 8], Birkhoff’s theorem is, in fact, a vicious circle arising from the introduction of inadmissible implicit transformations which eliminate in advance the boundary conditions defining the radial motion of the sphere bounding the matter, namely the boundary conditions inducing the non-stationary states of the gravitational field. In the present paper we deal with the rigorous mathematical theory of the subject and put forward the corresponding form of the spacetime metric in order to prepare a thorough study of the equations of gravitation related to the dynamical states of the gravitational field.

  20. Pulsational constraints to the metallicity gradient in the Galactic disk

    Science.gov (United States)

    Caputo, F.; Marconi, M.; Musella, I.; Pont, F.

    2001-06-01

    BVI data of Galactic Cepheids observed in the solar neighborhood and in the outer disk are analyzed on the basis of nonlinear, non-local and time-dependent convective pulsating models computed for different assumptions on the chemical composition. We show that the theoretical color-color, period-luminosity, and period-luminosity-color relations, as predicted by the models with varying metal content, provide the way to simultaneously estimate the true distance modulus mu_0 and the metal content Z of each individual variable. On this basis, we estimate that the metallicity distribution of Cepheids with Galactocentric distances d from ~ 6 to ~ 19 kpc can be represented by a linear gradient of -0.05 +/- 0.01 dex kpc-1, which is close to previous empirical determinations based on Cepheids, Planetary Nebulae and HII regions. However, our results are not excluding a different scenario, such as a two-zone model with a discontinuity in metallicity near d=10 kpc (see Twarog et al. 1997).

  1. Quantifying Temporal and Spatial Characteristics of Pulsating Aurora

    Science.gov (United States)

    Marchese, A. K.; Samara, M.; Michell, R.

    2017-12-01

    Aurorae are phenomena of colorful light due to charged solar wind particles colliding with gases in Earth's atmosphere. These events tend to be more prominent in higher latitudes since the particles travel along the magnetic field lines until they reach the poles where they enter the atmosphere. The effects of these energetic particles, however, also may damage technology. It is important to study aurorae to understand solar activity and how the magnetosphere responds to it to better deal with these problems. Imagers are located in Montana and Alaska facing towards the sky in order to take pictures of the aurora. Using the data from the imagers, numerous mathematical techniques were applied in order to extract quantitative information from the pictures to analyze pulsating aurora and study the differences between the aurora in Alaska and Montana. The two locations are at different latitudes and, thus, it is expected that they have different characteristics. Alaska, which is at a higher latitude, should have a more intense aurora than Montana.

  2. New Bounce Size Estimate for the Pulsating Universe

    Science.gov (United States)

    Tangherlini, Frank

    2001-04-01

    The pulsating model introduces an energy-momentum tensor for the vacuum that differs from the standard cosmological term and also quintessence. Although like them, it exhibits negative pressure, unlike them, its energy density is negative. It is of the same form as the CMB radiation tensor, but opposite in sign. When it dominates the CMBR, it gives rise to a bounce (for a flat or open universe), and for a closed universe, an infinite succession of bounces. Since the theory does not predict bounce size, one has to estimate. If the bounce is sufficiently small, and hence the background temperature is high enough to disintegrate heavy nuclei, presumably formed in the previous cycle of the universe, so that standard initial conditions for nucleosynthesis prevail, then the net mass at the bounce can be, depending on Ω, about the mass of a galaxy (due to cancellation of mass by vacuum energy), and the bounce size would be that of its Schwarzschild radius. However the model does not permit the universe to be accelerating at the present epoch, and hence disagrees with the predominant interpretation of the Type Ia supernovae observations.

  3. Quasiperiodic ULF-pulsations in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Kleindienst

    2009-02-01

    Full Text Available Recent magnetic field investigations made onboard the Cassini spacecraft in the magnetosphere of Saturn show the existence of a variety of ultra low frequency plasma waves. Their frequencies suggest that they are presumably not eigenoscillations of the entire magnetospheric system, but excitations confined to selected regions of the magnetosphere. While the main magnetic field of Saturn shows a distinct large scale modulation of approximately 2 nT with a periodicity close to Saturn's rotation period, these ULF pulsations are less obvious superimposed oscillations with an amplitude generally not larger than 3 nT and show a package-like structure. We have analyzed these wave packages and found that they are correlated to a certain extent with the large scale modulation of the main magnetic field. The spatial localization of the ULF wave activity is represented with respect to local time and Kronographic coordinates. For this purpose we introduce a method to correct the Kronographic longitude with respect to a rotation period different from its IAU definition. The observed wave packages occur in all magnetospheric regions independent of local time, elevation, or radial distance. Independent of the longitude correction applied the wave packages do not occur in an accentuated Kronographic longitude range, which implies that the waves are not excited or confined in the same selected longitude ranges at all times or that their lifetime leads to a variable phase with respect to the longitudes where they have been exited.

  4. High-Speed Hubble Space Telescope Ultraviolet photometry of two DB white dwarfs: Nonradial and radial pulsations

    Science.gov (United States)

    Kawaler, Steven D.; Bond, Howard E.; Sherbert, Lisa E.; Watson, Todd K.

    1994-01-01

    We observed two DB white dwarf stars with the High Speed Photometer aboard the Hubble Space Telescope. The two targets, the nonradial pulsator GD 358, and PG 0112+104, a non-pulsating white dwarf with similar temperature, were each observed for 1800 s with a time resolution of 10 ms. We used the F140LP configuration, which gives a broadband response in the UV between 1400 and 3000 A. The data clearly show the long period (about 700 s) pulsations in GD 358. Comparison with optical observations obtained two weeks earlier shows that the amplitude of the pulsations in the UV is approximately 1.4 times higher, consistent with nonradial pulsations due solely to temperature changes at constant radius. The high time resolution of these observations allows us to search for high-frequency pulsations (such as p modes or high overtone radial modes). No firm evidencefor high-frequency pulsations was seen in either object between 1 and 12 Hz. Correlation analysis of GD 358 shows no clear signal of multifrequency high overtone radial pulsations at the 0.00075 mag level, with no individual modes above the 0.0016 mag level. Upper limits for PG 0112+104 are approximately 2 times higher than for GD 358. Implications of this study for the theory of white dwarf pulsations are discussed.

  5. First Kepler results on compact pulsators - II. KIC 010139564, a new pulsating subdwarf B (V361 Hya) star with an additional low-frequency mode

    DEFF Research Database (Denmark)

    Kawaler, Stephen; Reed, M.D.; Quint, A.C.

    2010-01-01

    curve suggest that a significant number of additional pulsation frequencies may be present. The long duration of the run, the extremely high duty cycle and the well-behaved noise properties allow us to explore the stability of the periodic variations, and to place strong constraints on how many of them...

  6. Optical observations of Magnetosphere-Ionosphere coupling: Inter-hemispheric electron reflections within pulsating aurora

    Science.gov (United States)

    Samara, M.; Michell, R.; Khazanov, G. V.; Grubbs, G. A., II

    2017-12-01

    Magnetosphere-Ionosphere coupling is exhibited in reflected primary and secondary electrons which constitute the second step in the formation of the total precipitating electron distribution. While they have largely been missing from the current theoretical studies of particle precipitation, ground based observations point to the existence of a reflected electron population. We present evidence that pulsating aurora is caused by electrons bouncing back and forth between the two hemispheres. This means that these electrons are responsible for some of the total light in the aurora, a possibility that has largely been ignored in theoretical models. Pulsating auroral events imaged optically at high time resolution present direct observational evidence in agreement with the inter-hemispheric electron bouncing predicted by the SuperThermal Electron Trans-port (STET) model. Immediately following each of the `pulsation-on' times are equally spaced, and subsequently fainter pulsations, which can be explained by the primary precipitating electrons reflecting upwards from the ionosphere, traveling to the opposite hemisphere, and reflecting upwards again. The high time-resolution of these data, combined with the short duration of the `pulsation-on' time ( 1 s) and the relatively long spacing between pulsations ( 6 to 9 s) made it possible to observe the faint optical pulses caused by the reflected electrons coming from the opposite hemisphere. These results are significant and have broad implications because they highlight that the formation of the auroral electron distributions within regions of diffuse and pulsating aurora contain contributions from reflected primary and secondary electrons. These processes can ultimately lead to larger fluxes than expected when considering only the primary injection of magnetospheric electrons.

  7. Impact of loaded sit-to-stand exercises at different speeds on the physiological cost of walking in children with spastic diplegia: A single-blind randomized clinical trial.

    Science.gov (United States)

    Kusumoto, Yasuaki; Nitta, Osamu; Takaki, Kenji

    2016-10-01

    In the present study, we aimed to determine whether similarly loaded sit-to-stand exercises at different speeds improve the physiological cost of walking in children with spastic diplegia. This design was a single-blind randomized clinical trial. Sixteen children with cerebral palsy (CP), aged 12-18 years, with a diagnosis of spastic diplegia, were randomly allocated to a slow loaded sit-to-stand exercise group (n=8) and a self-paced loaded sit-to-stand exercise group (n=8). Loaded sit-to-stand exercise was conducted at home for 15min, 4 sets per day, 3-4days per week, for 6 weeks. The patients were evaluated immediately before the intervention and after the training. Lower limb muscle strength using a hand-held dynamometer, selective voluntary motor control using SCALE, 6-min walk distance (6MWD), and Physiological Cost Index (PCI) were measured. The 6MWD showed a significant difference before and after intervention. PCI showed a significant difference between the two groups and the two time points. 6MWD and the PCI improved after intervention in the slow sit-to-stand exercise group. Compared to loaded sit-to-stand exercise at a regular speed, slow low-loaded sit-to-stand exercise improved the 6MWD and PCI in children with CP, suggesting that this decrease in speed during exercise improves the physiological cost of walking in these children. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Dynamic loading of galvanized parts

    Directory of Open Access Journals (Sweden)

    Michal Černý

    2010-01-01

    Full Text Available This work is divided into two parts: the theoretical part includes actual knowledge and points of view about degradation processes in construction materials, anticorrosion protection, zinc coat composition and high frequency fatigue. The laboratory part follow-up existing regulations contents Czech standards and formulate specifications for acquisition of objective information from acceleration la­bo­ra­to­ry tests in condensation chests, mechanical high frequency fatigue tests on pulsator machine and possibilities of evaluation of fatigue tests. Laboratory findings declare to fundamental types of damage of constructions with anticorrosion protection in real loading conditions with dynamic high frequency character. Laboratory tests were made in sulphide and chloride environments.

  9. The pulsation index, effective temperature, and thickness of the hydrogen layer in the pulsating DA white dwarf G117-B15A

    Science.gov (United States)

    Robinson, E. L.; Mailloux, T. M.; Zhang, E.; Koester, D.; Stiening, R. F.; Bless, R. C.; Percival, J. W.; Taylor, M. J.; Van Citters, G. W.

    1995-01-01

    We have measured the amplitude of the 215 s pulsation of the pulsating DA white dwarf, or ZZ Ceti star, G117-B15A in six passbands with effective wavelengths from 1570 to 6730 A. We find that the index of the pulsation is l = 1 with a high degree of confidence, the first unambiguous determination of l for a pulsation of a ZZ Ceti star. We also find that log g and T(sub eff) are tightly correlated for model atmospheres that fit the data, such that at log g = 7.5 the temperature is 11,750 K and at log g = 8.0 the temperature is 12,375 K. Adopting log g = 7.97 +/- 0.06 from published observations of the optical spectrum of G117-B15A, the correlation yields T(sub eff) = 12,375 +/- 125 K. This temperature is free of flux calibration errors and should be substantially more reliable than temperatures derived for IUE spectra. Since G117-B15A is thought to lie close to the blue edge of the ZZ Ceti instability strip, this low temperature also implies a low temperature for the blue edge. Using pulsation models calculated by Fontaine et al. (1992) and Bradley (1994), we find that the mass of the hydrogen layer in G117-B15A lies between 1.0 x 10(exp -6) solar mass (for k = 1) and 8 x 10(exp -5) solar mass (for k = 2). This range of masses is (barely) consistent with the masses predicted by recent models for the ejection of planetary nebulae, (8-13) x 10(exp -5) solar mass. The mass is too large to be consistent with models invoking thin hydrogen layers to explain the spectral evolution of white dwarfs.

  10. Possible link of sudden onset and short-time periodic pulsation of polar mesosphere summer echoes to ULF Pc5 geomagnetic pulsations and solar wind dynamic pressure enhancement

    Science.gov (United States)

    Lee, Y.; Kirkwood, S.; Kwak, Y. S.

    2016-12-01

    The EISCAT VHF incoherent scatter radar in Tromsö, Norway, makes occasional observations of electron densities and Polar Mesosphere Summer Echoes, in the summer polar D-region ionosphere. In one of those datasets, pulsating polar mesospheric summer echoes (PMSE) are observed, with periodicities in the ultra-low frequency (ULF) Pc5 band (1.6-6.7 mHz), following an abrupt increase of the radar reflectivity when a geomagnetic field excursion is started, in turn linked to dynamic pressure (Pdyn) enhancement in the solar wind. At the excursion of the magnetic field, at auroral altitudes of 90 km and above, electron density is abruptly enhanced, followed by a series of short-lived peaks, superimposed on an enhanced level. The short-lived peaks are likely a signature of transient Pc5 geomagnetic pulsations and associated energetic electron precipitation from pitch-angle scattering into the loss cone in the magnetosphere. At the same time, at altitudes around 80-90 km, a sharp increase of PMSE reflectivity occurs, 100 times greater than the increase of electron density, and is followed by pulsating PMSE reflectivity with periodicities in the Pc5 band, increasing and decreasing in magnitude during the course of the next hour. The increase of the pulsation magnitude may be attributed to an increase of high-energy electron precipitation flux ( >30 keV) penetrating to at least the height of maximum PMSE reflectivity. This study suggests that Pc5 pulsation bursts in both magnetic field and high energy electron precipitation could play a crucial role in producing PMSE fluctuations on minute-to-minute time scales.

  11. Hydrodynamics of piston-driven laminar pulsating flow: Part 2. Fully developed flow

    International Nuclear Information System (INIS)

    Aygun, Cemalettin; Aydin, Orhan

    2014-01-01

    Highlights: • The piston-driven laminar pulsating flow in a pipe is studied. • Fully developed flow is examined analytically, numerically and experimentally. • An increase in F results an increase in the amplitude of the centerline velocity. • The characters of the radial velocity profiles critically depend on both the frequency and the phase angle. • The near/off-wall flow reversals are observed for F = 105, 226 and 402. - Abstract: Piston-driven pulsating flow is a specific type of pressure-driven pulsating flows. In this study, piston-driven laminar pulsating flow in a pipe is studied. This study mainly exists of two parts: developing flow and fully developed flow. In this part, hydrodynamically fully developed flow is examined analytically, numerically and experimentally. A constant value of the time-averaged Reynolds number is considered, Re = 1000. In the theoretical studies, both analytical and numerical, an inlet velocity profile representing the experimental case, i.e., the piston driven flow, is assumed. In the experiments, in the hydrodynamically fully developed region, radial velocity distribution and pressure drop are obtained using hot-wire anemometer and pressure transmitter, respectively. The effect pulsation frequency on the friction coefficient as well as velocity profiles are obtained. A good agreement is observed among analytical, numerical and experimental results

  12. Electrochemical Drilling of Deep Small Holes in Titanium Alloys with Pulsating Electrolyte Flow

    Directory of Open Access Journals (Sweden)

    Yongbin Zeng

    2014-06-01

    Full Text Available Inherent characteristics of electrochemical drilling (ECD mean that it is a major solution to the machining of deep small holes in difficult-to-cut materials. The removal of insoluble by-products from the machining gap determines the accuracy of control and limits process capacity. Pulsating electrolyte flow is introduced to enhance the removal rate of insoluble products by reducing the hold-down pressure caused by the electrolyte. Experiments are conducted to optimize a stimulus signal for the pulsation and to investigate the electrolyte pulsation frequency, pulsation amplitude, applied voltage, and electrode feed rate in the machining of deep small holes. The results indicate that optimized pulsating flow is effective in accelerating by-product removal and enhancing machining accuracy and maximum machining depth. With the optimized parameters of 5 Hz in frequency, 0.2 MPa in amplitude, and 0.5 MPa in average pressure, a deep hole was machined in titanium alloys of 20 mm depth and 1.97 mm averaged diameter.

  13. Kinematics of pulsating flow in the entry region of the channel with discrete roughness elements

    Science.gov (United States)

    Dushin, N. S.; Mikheev, N. I.; Paereliy, A. A.; Gazizov, I. M.; Shakirov, R. R.

    2017-11-01

    One of the efficient ways to disrupt and redevelop the boundary layer for the purpose of heat transfer enhancement is application of discrete roughness elements in the form of spanwise ribs. To further improve the efficiency of this method, the flow can be exposed to some additional forcing. Forced pulsations of flow are considered to be a promising technique. The paper studies the combined effect of discrete roughness elements and forced pulsations of flow on heat transfer. Turbulent pulsating flow in the entrance region of the channel with discrete roughness elements has been considered. The Reynolds number based on the channel hydraulic diameter was ReD = 18200, relative rib height e/h = 0.117, rib pitch p/e = 10. Strouhal number, Sr, and relative amplitude of forced velocity pulsations, β, varied in the following ranges: Sr = 0.04 … 0.6; β = 0.15 … 0.8. The Strouhal number was based on the bulk velocity and the rib height. Smoke visualization of flow downstream of the third rib in the channel has revealed the effects introduced by forced periodic pulsations to mass transfer behavior. The obtained flow behavior allowed qualitative and quantitative classification of the flow pattern.

  14. Discovery of Three Pulsating, Mixed-atmosphere, Extremely Low-mass White Dwarf Precursors

    Science.gov (United States)

    Gianninas, A.; Curd, Brandon; Fontaine, G.; Brown, Warren R.; Kilic, Mukremin

    2016-05-01

    We report the discovery of pulsations in three mixed-atmosphere, extremely low-mass white dwarf (ELM WD, M ≤slant 0.3 M ⊙) precursors. Following the recent discoveries of pulsations in both ELM and pre-ELM WDs, we targeted pre-ELM WDs with mixed H/He atmospheres with high-speed photometry. We find significant optical variability in all three observed targets with periods in the range 320-590 s, consistent in timescale with theoretical predictions of p-mode pulsations in mixed-atmosphere ≈0.18 M ⊙ He-core pre-ELM WDs. This represents the first empirical evidence that pulsations in pre-ELM WDs can only occur if a significant amount of He is present in the atmosphere. Future, more extensive, timeseries photometry of the brightest of the three new pulsators offers an excellent opportunity to constrain the thickness of the surface H layer, which regulates the cooling timescales for ELM WDs. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  15. Development of pulsating twin jets mechanism for mixing flow heat transfer analysis.

    Science.gov (United States)

    Gitan, Ali Ahmed; Zulkifli, Rozli; Abdullah, Shahrir; Sopian, Kamaruzzaman

    2014-01-01

    Pulsating twin jets mechanism (PTJM) was developed in the present work to study the effect of pulsating twin jets mixing region on the enhancement of heat transfer. Controllable characteristics twin pulsed jets were the main objective of our design. The variable nozzle-nozzle distance was considered to study the effect of two jets interaction at the mixing region. Also, the phase change between the frequencies of twin jets was taken into account to develop PTJM. All of these factors in addition to the ability of producing high velocity pulsed jet led to more appropriate design for a comprehensive study of multijet impingement heat transfer problems. The performance of PTJM was verified by measuring the pulse profile at frequency of 20 Hz, where equal velocity peak of around 64 m/s for both jets was obtained. Moreover, the jet velocity profile at different pulsation frequencies was tested to verify system performance, so the results revealed reasonable velocity profile configuration. Furthermore, the effect of pulsation frequency on surface temperature of flat hot plate in the midpoint between twin jets was studied experimentally. Noticeable enhancement in heat transfer was obtained with the increasing of pulsation frequency.

  16. STRAIN ELASTOGRAPHY USING DOBUTAMINE-INDUCED CAROTID ARTERY PULSATION IN CANINE THYROID GLAND.

    Science.gov (United States)

    Lee, Gahyun; Jeon, Sunghoon; Lee, Sang-Kwon; Kim, Hyunwoo; Yu, Dohyeon; Choi, Jihye

    2015-01-01

    Thyroid disease is common in dogs and conventional ultrasonography is a standard diagnostic test for diagnosis and treatment planning. Strain elastography can provide additional information about tissue stiffness noninvasively after applying external or internal compression. However, natural carotid artery pulsations in the canine thyroid gland are too weak to maintain sufficient internal compression force. The objective of the present study was to describe the feasibility of strain elastography for evaluating the canine thyroid gland and the repeatability of dobutamine-induced carotid artery pulsation as an internal compression method. In seven healthy Beagle dogs, strain on each thyroid lobe was induced by external compression using the ultrasound probe and internal compression using carotid artery pulsation after dobutamine infusion. The thyroid appeared homogeneously green and the subcutaneous fat superficial to the thyroid lobe appeared blue. Strain values and strain ratios did not differ among dogs or between the left and right lobes. Interobserver repeatability was excellent for both compression methods. Intraobserver repeatability of the strain ratio measured using the carotid artery pulsation method (intraclass coefficient correlation = 0.933) was higher than that measured using the external compression method (0.760). Mean strain values of thyroid lobes for the external compression method (142.93 ± 6.67) differed from the internal method (147.31 ± 8.24; P thyroid stiffness in dogs. Carotid artery pulsation induced by dobutamine infusion can be used for canine thyroid strain elastography with excellent repeatability. © 2015 American College of Veterinary Radiology.

  17. QUASI-PERIODIC PULSATIONS DURING THE IMPULSIVE AND DECAY PHASES OF AN X-CLASS FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, L. A.; Gallagher, P. T. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Dennis, B. R.; Ireland, J.; Inglis, A. R.; Ryan, D. F. [Solar Physics Laboratory, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-08-20

    Quasi-periodic pulsations (QPPs) are often observed in X-ray emission from solar flares. To date, it is unclear what their physical origins are. Here, we present a multi-instrument investigation of the nature of QPP during the impulsive and decay phases of the X1.0 flare of 2013 October 28. We focus on the character of the fine structure pulsations evident in the soft X-ray (SXR) time derivatives and compare this variability with structure across multiple wavelengths including hard X-ray and microwave emission. We find that during the impulsive phase of the flare, high correlations between pulsations in the thermal and non-thermal emissions are seen. A characteristic timescale of ∼20 s is observed in all channels and a second timescale of ∼55 s is observed in the non-thermal emissions. SXR pulsations are seen to persist into the decay phase of this flare, up to 20 minutes after the non-thermal emission has ceased. We find that these decay phase thermal pulsations have very small amplitude and show an increase in characteristic timescale from ∼40 s up to ∼70 s. We interpret the bursty nature of the co-existing multi-wavelength QPPs during the impulsive phase in terms of episodic particle acceleration and plasma heating. The persistent thermal decay phase QPPs are most likely connected with compressive magnetohydrodynamic processes in the post-flare loops such as the fast sausage mode or the vertical kink mode.

  18. Kepler observations of rapidly oscillating Ap, δ Scuti and γ Doradus pulsations in Ap stars

    DEFF Research Database (Denmark)

    Balona, Luis A.; Cunha, Margarida S.; Kurtz, Donald W.

    2011-01-01

    Observations of the A5p star KIC 8677585 obtained during the Kepler 10-d commissioning run with 1-min time resolution show that it is a rapidly oscillating Ap (roAp) star with several frequencies with periods near 10 min. In addition, a low frequency at 3.142 d−1 is also clearly present....... Multiperiodic γ Doradus (γ Dor) and δ Scuti (δ Sct) pulsations, never before seen in any Ap star, are present in Kepler observations of at least three other Ap stars. Since γ Dor pulsations are seen in Ap stars, it is likely that the low frequency in KIC 8677585 is also a γ Dor pulsation. The simultaneous...... presence of both γ Dor and roAp pulsations and the unexpected detection of δ Sct and γ Dor pulsations in Ap stars present new opportunities and challenges for the interpretation of these stars. Since it is easy to confuse Am and Ap stars at classification dispersions, the nature of these Ap stars...

  19. Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

    Energy Technology Data Exchange (ETDEWEB)

    Wit, Julien de [Department of Earth, Atmospheric and Planetary Sciences, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Lewis, Nikole K. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Knutson, Heather A.; Batygin, Konstantin [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Fuller, Jim [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Antoci, Victoria [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Fulton, Benjamin J. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Laughlin, Gregory [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Deming, Drake [Department of Astronomy, University of Maryland at College Park, College Park, MD 20742 (United States); Shporer, Avi [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91009 (United States); Cowan, Nicolas B. [Department of Physics, Department of Earth and Planetary Sciences, McGill University, 3550 rue University, Montreal, QC H3A 2A7 (Canada); Agol, Eric [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Burrows, Adam S. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

    2017-02-20

    Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μ m observations with the Spitzer Space Telescope . The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μ m photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

  20. Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

    International Nuclear Information System (INIS)

    Wit, Julien de; Lewis, Nikole K.; Knutson, Heather A.; Batygin, Konstantin; Fuller, Jim; Antoci, Victoria; Fulton, Benjamin J.; Laughlin, Gregory; Deming, Drake; Shporer, Avi; Cowan, Nicolas B.; Agol, Eric; Burrows, Adam S.; Fortney, Jonathan J.; Langton, Jonathan; Showman, Adam P.

    2017-01-01

    Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μ m observations with the Spitzer Space Telescope . The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μ m photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

  1. Study on the Pressure Pulsation inside Runner with Splitter Blades in Ultra-High Head Turbine

    International Nuclear Information System (INIS)

    Meng, L; Zhang, S P; Zhou, L J; Wang, Z W

    2014-01-01

    Runners with splitter blades were used widely for the high efficiency and stability. In this paper, the unsteady simulation of an ultra-high head turbine at the best efficiency point, 50% and 75% discharge points were established, to analyze the pressure pulsation in the vaneless space, rotating domain and the draft tube. First of all, runners with different length splitter blades and without splitter blades were compared to learn the efficiency and the pressure distribution on the blade surface. And then the amplitude of the pressure pulsation was analysed. The peak efficiency of the runner with splitter blades is remarkably higher than that of the corresponding impeller without splitter blades. And the efficiency of the turbine is the highest when the length ratio of the splitter blades is 0.75 times the main blades. The pressure pulsation characteristics were also influenced, because the amplitudes of the pulsation induced by the RSI phenomenon were changed as a result of more blades. At last, the best design plan of the length of the splitter blades (length ratio=0.825) was obtained, which improved the pressure pulsation characteristics without significant prejudice to the efficiency

  2. On the effect of pulsating flow on surge margin of small centrifugal compressors for automotive engines

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, J.; Climent, H.; Guardiola, C.; Tiseira, A. [CMT-Motores Termicos, Universidad Politecnica de Valencia (Spain); Camino de Vera s/n, E 46022, Valencia (Spain)

    2009-11-15

    Surge is becoming a limiting factor in the design of boosting systems of downsized diesel engines. Although standard compressor flowcharts are used for the selection of those machines for a given application, on-engine conditions widely differ from steady flow conditions, thus affecting compressor behaviour and consequently surge phenomenon. In this paper the effect of pulsating flow is investigated by means of a steady gas-stand that has been modified to produce engine-like pulsating flow. The effect of pressure pulses' amplitude and frequency on the compressor surge line location has been checked. Results show that pulsating flow in the 40-67 Hz range (corresponding to characteristic pulsation when boosting an internal combustion engine) increases surge margin. This increased margin is similar for all the tested frequencies but depends on pulsation amplitude. In a further step, a non-steady compressor model is used for modelling the tests, thus allowing a deeper analysis of the involved phenomena. Model results widely agree with experimental results. (author)

  3. An Analysis of Pulsating Subdwarf B Star EPIC 203948264 Observed During Campaign 2 of K2

    Directory of Open Access Journals (Sweden)

    Ketzer Laura

    2017-01-01

    Full Text Available We present a preliminary analysis of the newly–discovered pulsating subdwarf B (sdB star EPIC 203948264. The target was observed for 83 days in short cadence mode during Campaign 2 of K2, the two–gyro mission of the Kepler space telescope. A time–series analysis of the data revealed 22 independent pulsation frequencies in the g–mode region ranging from 100 to 600 μHz (0:5 to 2:8 hours. The main method we use to identify pulsation modes is asymptotic period spacing, and we were able to assign all but one of the pulsations to either l = 1 or l = 2. The average period spacings of both sequences are 261:34 ± 0.78 s and 151:18 ± 0.34 s, respectively. The pulsation amplitudes range from 0.77 ppt down to the detection limit at 0.212 ppt, and are not stable over the duration of the campaign. We detected one possible low–amplitude, l = 2, rotationally split multiplet, which allowed us to constrain the rotation period to 46 days or longer. This makes EPIC 203948264 another slowly rotating sdB star.

  4. Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

    Science.gov (United States)

    Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Cacciari, C.; Clementini, C.

    2016-05-01

    We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a least squares deconvolution (LSD) of the line profiles in order to an- alyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (+- 2 kms^-1) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 kms^-1 even with a low number of high- resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

  5. Resistance Training with Single vs. Multi-joint Exercises at Equal Total Load Volume: Effects on Body Composition, Cardiorespiratory Fitness, and Muscle Strength

    Directory of Open Access Journals (Sweden)

    Antonio Paoli

    2017-12-01

    Full Text Available The present study aimed to compare the effects of equal-volume resistance training performed with single-joint (SJ or multi-joint exercises (MJ on VO2max, muscle strength and body composition in physically active males. Thirty-six participants were divided in two groups: SJ group (n = 18, 182.1 ± 5.2, 80.03 ± 2.78 kg, 23.5 ± 2.7 years exercised with only SJ exercises (e.g., dumbbell fly, knee extension, etc. and MJ group (n = 18, 185.3 ± 3.6 cm, 80.69 ± 2.98 kg, 25.5 ± 3.8 years with only MJ exercises (e.g., bench press, squat, etc.. The total work volume (repetitions × sets × load was equated between groups. Training was performed three times a week for 8 weeks. Before and after the training period, participants were tested for VO2max, body composition, 1 RM on the bench press, knee extension and squat. Analysis of covariance (ANCOVA was used to compare post training values between groups, using baseline values as covariates. According to the results, both groups decreased body fat and increased fat free mass with no difference between them. Whilst both groups significantly increased cardiorespiratory fitness and maximal strength, the improvements in MJ group were higher than for SJ in VO2max (5.1 and 12.5% for SJ and MJ, bench press 1 RM (8.1 and 10.9% for SJ and MJ, knee extension 1 RM (12.4 and 18.9% for SJ and MJ and squat 1 RM (8.3 and 13.8% for SJ and MJ. In conclusion, when total work volume was equated, RT programs involving MJ exercises appear to be more efficient for improving muscle strength and maximal oxygen consumption than programs involving SJ exercises, but no differences were found for body composition.

  6. Making Sense Out of Pulsating Pre-ELM and ELM White Dwarfs

    Science.gov (United States)

    Fontaine, G.; Istrate, A.; Gianninas, A.; Brassard, P.; Van Grootel, V.

    2017-03-01

    We present a unified view of pulsations in both pre-ELM and ELM white dwarfs within the framework of state-of-the-art binary evolution calculations that take into account the combined effects of diffusion and rotational mixing. We find that rotational mixing is able to maintain against settling a sufficient amount of helium in the envelope in order to fuel pulsations through He II-He III ionization on the pre-ELM branch of the evolutionary track in the spectroscopic HR diagram. By the time such a low-mass white dwarf enters the ZZ Ceti instability strip on the cooling branch, settling has taken over rotational mixing and produced a pure H envelope. Such a star then pulsates again, but, this time, as a DA white dwarf of the ZZ Ceti type.

  7. On application of the SSA method in the pulsating combustion studies

    Science.gov (United States)

    Berg, I. A.; Porshnev, S. V.; Oshchepkova, V. Y.

    2017-11-01

    Pulsating combustion is among combustion control methods used to suppress formation of NOx. An upgraded automatic setup with a direct gas injection burner was used for pulsating torch studies. Experiments resulted in obtaining time series of torch area changing in longitudinal section. Singular Spectral Analysis method (SSA) upgraded to allow for choosing the size of the window was used. Spectra of the extracted components of the time series demonstrate that they contain periodic components that match the fuel supply valve on/off cycle frequency. When increasing the control frequency the spectrum of the extracted component of the time series gets broader. With further frequency increase, the spectrum approaches that of no control action and the system operates in quasi-continuous mode. The results correspond to the results obtained earlier through the spectrum analysis that confirms the phenomenon of periodic change of the torch core area in the longitudinal section under pulsating supply of fuel.

  8. Finding the first cosmic explosions. III. Pulsational pair-instability supernovae

    International Nuclear Information System (INIS)

    Whalen, Daniel J.; Smidt, Joseph; Even, Wesley; Fryer, Chris L.; Woosley, S. E.; Heger, Alexander; Stiavelli, Massimo

    2014-01-01

    Population III supernovae have been the focus of growing attention because of their potential to directly probe the properties of the first stars, particularly the most energetic events that can be seen at the edge of the observable universe. But until now pulsational pair-instability supernovae, in which explosive thermonuclear burning in massive stars fails to unbind them but can eject their outer layers into space, have been overlooked as cosmic beacons at the earliest redshifts. These shells can later collide and, like Type IIn supernovae, produce superluminous events in the UV at high redshifts that could be detected in the near infrared today. We present numerical simulations of a 110 M ☉ pulsational pair-instability explosion done with the Los Alamos radiation hydrodynamics code Radiation Adaptive Grid Eulerian. We find that collisions between consecutive pulsations are visible in the near infrared out to z ∼ 15-20 and can probe the earliest stellar populations at cosmic dawn.

  9. Continuous vs. pulsating flow boiling. Part 2: Statistical comparison using response surface methodology

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2016-01-01

    Response surface methodology is used to investigate an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The flow pulsations are introduced by a flow modulating expansion device and compared with the baseline continuous flow provided by a stepper......-motor expansion valve. Two experimental designs (data point sets) are generated using a modified Central Composite Design for each valve and their response surfaces are compared using the quadratic model. Statistical information on the significant model terms are used to clarify whether the effect of fluid flow....... The response surface comparison reveals that the flow pulsations improves the time-averaged heat transfer coefficient by as much as 10 % at the smallest cycle time compared with continuous flow. On the other hand, at highest cycle time and heat flux, the reduction may be as much as 20 % due to significant dry...

  10. On the Field of a Spherical Charged Pulsating Distribution of Matter

    Directory of Open Access Journals (Sweden)

    Stavroulakis N.

    2010-10-01

    Full Text Available In the theory of the gravitational field generated by an isotropic spherical mass, the spheres centered at the origin of $R^3$ are non-Euclidean objects, so that each of them possesses a curvature radius distinct from its Euclidean radius. The classical theory suppresses this distinction and consequently leads to inadmissible errors. Specifically, it leads to the false idea that the field of a pulsating source is static. In a number of our previous publications (see references, we have exposed the inevitable role that the curvature radius plays and demonstrated that the field generated by a pulsating not charged spherical course is dynamical. In the present paper we prove that the curvature radius plays also the main role in the description of the gravitational field generated by a charged pulsating source.

  11. K2 Campaign 5 observations of pulsating subdwarf B stars: binaries and super-Nyquist frequencies

    Science.gov (United States)

    Reed, M. D.; Armbrecht, E. L.; Telting, J. H.; Baran, A. S.; Østensen, R. H.; Blay, Pere; Kvammen, A.; Kuutma, Teet; Pursimo, T.; Ketzer, L.; Jeffery, C. S.

    2018-03-01

    We report the discovery of three pulsating subdwarf B stars in binary systems observed with the Kepler space telescope during Campaign 5 of K2. EPIC 211696659 (SDSS J083603.98+155216.4) is a g-mode pulsator with a white dwarf companion and a binary period of 3.16 d. EPICs 211823779 (SDSS J082003.35+173914.2) and 211938328 (LB 378) are both p-mode pulsators with main-sequence F companions. The orbit of EPIC 211938328 is long (635 ± 146 d) while we cannot constrain that of EPIC 211823779. The p modes are near the Nyquist frequency and so we investigate ways to discriminate super- from sub-Nyquist frequencies. We search for rotationally induced frequency multiplets and all three stars appear to be slow rotators with EPIC 211696659 subsynchronous to its orbit.

  12. Moment of Inertia Dependence of Vertical Axis Wind Turbines in Pulsating Winds

    Directory of Open Access Journals (Sweden)

    Yutaka Hara

    2012-01-01

    Full Text Available Vertical Axis Wind Turbines (VAWTs are unaffected by changes in wind direction, and they have a simple structure and the potential for high efficiency due to their lift driving force. However, VAWTs are affected by changes in wind speed, owing to effects originating from the moment of inertia. In this study, changes in the rotational speed of a small VAWT in pulsating wind, generated by an unsteady wind tunnel, are investigated by varying the wind cycle and amplitude parameters. It is shown that the responses observed experimentally agree with simulations based on torque characteristics obtained under steady rotational conditions. Additionally, a simple equation expressing the relationship between the rotational change width and amplitude of the pulsating wind is presented. The energy efficiency in a pulsating wind remains constant with changes in both the moment of inertia and the wind cycle; however, the energy efficiency decreases when the wind amplitude is large.

  13. On a method of numerical calculation of nonlinear radial pulsations of stars

    International Nuclear Information System (INIS)

    Kosovichev, A.G.

    1984-01-01

    Some features of using the finite difference method for numerical investigation of nonradial pulsations of stars were considered. The mathematical model of these pulsations is described by time-dependent gasdynaMic equations with gravity. A one-dimentional (spherically-symmetric) case is considered. It was obtained a two-parametric family of ultimate conservative difference schemes where the diffepence analogy of the main conservative laws as well as the additional relations for the balance to individual kinds of energy are performed. Such difference schemes provide more exact calculation of nonlinear flows with shocks as compared with the other difference schemes with the same order of approximation. The methods of numerical solution of implicit (absolute stable) difference schemes for a given family were considered. The coupled equations are solved through iterative Newton method Using martrix and separate successive eliminations. Numerical method can be used for calculation of large amplitude radial pulsations of stars

  14. Unraveling the oscillations of the richest pulsating hydrogen-atmosphere white dwarf

    Science.gov (United States)

    Hermes, JJ

    2016-10-01

    Most stars in our Galaxy will end or have already ended their lives as white dwarf stars, making them important benchmarks for stellar evolution. Here we propose to obtain COS far-ultraviolet spectroscopy of a pulsating hydrogen-atmosphere white dwarf (DAV) with extensive, space-based photometry obtained by the Kepler spacecraft during the K2 mission. The pulsation spectrum is the richest of any DAV collected to date, but to extract any information about the white dwarf interior we must identify the spherical degree (l) of the modes present. Our time-tagged ultraviolet observations will enable us to identify the spherical degree of the highest-amplitude pulsation modes, since the ratios of the ultraviolet-to-optical pulsation amplitudes strongly depend on the geometry of the pulsation modes. This will decisively determine if most of the modes present are a series of l=3 modes, as it appears from the frequency multiplets in the K2 data; however, l=3 modes have never been clearly identified in a pulsating white dwarf. Our far-ultraviolet spectroscopy, covering the H2/H2+ quasi-molecular satellites around 1400 and 1600 AA, will also measure the white dwarf temperature and mass to an accuracy unachievable from the ground. This robust temperature and mass will anchor our detailed asteroseismic investigation of this stellar remnant. The unique combination of HST and Kepler observations will make this white dwarf a benchmark for the unprecedented opportunities for white dwarf archaeology enabled by the original Kepler mission and its extension into the ecliptic, K2.

  15. Association between substorm onsets in auroral all-sky images and geomagnetic Pi2pulsations

    Science.gov (United States)

    Miura, T.; Ieda, A.; Teramoto, M.; Kawashima, T.

    2017-12-01

    Substorms are explosive disturbances in the magnetosphere and ionosphere of Earth. Substorm onsets are often identified usingsudden auroral brightenings (auroral breakup) or geomagnetic Pi2 pulsations. These auroral brightenings and Pi2 pulsations aresupposed to occur simultaneously within approximately 1 min of each other. However, as auroral brightenings typically includea two-stage development, this simultaneity is not straightforward. In this study, we clarify the correspondence between Pi2 pulsations and auroral brightenings, including the two-stage development.The first stage of the development is the sudden brightening of an auroral arc near the midnight (initial brightening)and the second stage is the poleward expansion of the auroral arc. We compared all-sky images (3 s resolution) in Canada andgeomagnetic observations (0.5-1 s resolution) in North and Central America, using data from the THEMIS project. In this study,we examined three substorms events that exhibit evidence of the two-stage auroral development. In the first event (4 March 2008), an auroral initial brightening occurred at 0533:57 UT and a poleward expansion was observedat 0538:12 UT (4 min after the initial brightening) in Gillam (magnetic latitude:66.0 °, longitude:333 °, MLT:22.9). In contract,the Pi2 pulsation started at 0539:30 UT, which is closer to the time of the poleward expansion, in Carson City (magnetic latitude:45.0 °, longitude:304 °). and San Juan (magnetic latitude:27.9 °, longitude:6.53 °). Thus, we consider this Pi2 pulsation ascorresponding to the poleward expansion rather than the initial brightening. This correspondence was also seen in the other twoevents, suggesting that it is not exceptional. We interpret that the Pi2 pulsation corresponds to the poleward expansion becauseboth are caused by the magnetic field dipolarization, which is a drastic change that propagates from low- to high-latitude fieldlines.

  16. A Large-Scale Search for Evidence of Quasi-Periodic Pulsations in Solar Flares

    Science.gov (United States)

    Inglis, A. R.; Ireland, J.; Dennis, B. R..; Hayes, L.; Gallagher, P.

    2016-01-01

    The nature of quasi-periodic pulsations (QPP) in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with QPP in solar flares, focusing on the 1300 s timescale. We analyze 675 M- and X-class flares observed by the Geostationary Operational Environmental Satellite (GOES) series in 18 soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyze Fermi/Gamma-ray Burst Monitor (GBM) 1525 keV X-ray data for each of these flares associated with a Fermi/GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, based on three tested models; a power-law plus a constant, a broken power-law plus constant, and a power-law-plus-constant with an additional QPP signature component. From this, we determine that approx. 30% of GOES events and approx. 8% of Fermi/GBM events show strong signatures consistent with classical interpretations of QPP. For the remaining events either two or more tested models cannot be strongly distinguished from each other, or the events are well-described by single power-law or broken power-law Fourier power spectra. For both instruments, a preferred characteristic time-scale of approx. 5-30 s was found in the QPP-like events, with no dependence on flare magnitude in either GOES or GBM data. We also show that individual events in the sample show similar characteristic time-scales in both GBM and GOES data sets. We discuss the implications of these results for our understanding of solar flares and possible QPP mechanisms.

  17. A LARGE-SCALE SEARCH FOR EVIDENCE OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARES

    International Nuclear Information System (INIS)

    Inglis, A. R.; Ireland, J.; Dennis, B. R.; Hayes, L; Gallagher, P.

    2016-01-01

    The nature of quasi-periodic pulsations (QPP) in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with QPP in solar flares, focusing on the 1–300 s timescale. We analyze 675 M- and X-class flares observed by the Geostationary Operational Environmental Satellite (GOES) series in 1–8 Å soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyze Fermi /Gamma-ray Burst Monitor (GBM) 15–25 keV X-ray data for each of these flares associated with a Fermi /GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, based on three tested models; a power-law plus a constant, a broken power-law plus constant, and a power-law-plus-constant with an additional QPP signature component. From this, we determine that ∼30% of GOES events and ∼8% of Fermi /GBM events show strong signatures consistent with classical interpretations of QPP. For the remaining events either two or more tested models cannot be strongly distinguished from each other, or the events are well-described by single power-law or broken power-law Fourier power spectra. For both instruments, a preferred characteristic timescale of ∼5–30 s was found in the QPP-like events, with no dependence on flare magnitude in either GOES or GBM data. We also show that individual events in the sample show similar characteristic timescales in both GBM and GOES data sets. We discuss the implications of these results for our understanding of solar flares and possible QPP mechanisms.

  18. A LARGE-SCALE SEARCH FOR EVIDENCE OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Inglis, A. R.; Ireland, J.; Dennis, B. R. [Solar Physics Laboratory, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Hayes, L; Gallagher, P. [Trinity College Dublin, Dublin (Ireland)

    2016-12-20

    The nature of quasi-periodic pulsations (QPP) in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with QPP in solar flares, focusing on the 1–300 s timescale. We analyze 675 M- and X-class flares observed by the Geostationary Operational Environmental Satellite (GOES) series in 1–8 Å soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyze Fermi /Gamma-ray Burst Monitor (GBM) 15–25 keV X-ray data for each of these flares associated with a Fermi /GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, based on three tested models; a power-law plus a constant, a broken power-law plus constant, and a power-law-plus-constant with an additional QPP signature component. From this, we determine that ∼30% of GOES events and ∼8% of Fermi /GBM events show strong signatures consistent with classical interpretations of QPP. For the remaining events either two or more tested models cannot be strongly distinguished from each other, or the events are well-described by single power-law or broken power-law Fourier power spectra. For both instruments, a preferred characteristic timescale of ∼5–30 s was found in the QPP-like events, with no dependence on flare magnitude in either GOES or GBM data. We also show that individual events in the sample show similar characteristic timescales in both GBM and GOES data sets. We discuss the implications of these results for our understanding of solar flares and possible QPP mechanisms.

  19. Thermal-Diffusional Instability in White Dwarf Flames: Regimes of Flame Pulsation

    OpenAIRE

    Xing, Guangzheng; Zhao, Yibo; Modestov, Mikhail; Zhou, Cheng; Gao, Yang; Law, Chung K.

    2017-01-01

    Thermal-diffusional pulsation behaviors in planar as well as outwardly and inwardly propagating white dwarf carbon flames are systematically studied. In the 1D numerical simulation, the asymptotic degenerate equation of state and simplified one-step reaction rates for nuclear reactions are used to study the flame propagation and pulsation in white dwarfs. The numerical critical Zel'dovich numbers of planar flames at different densities ($\\rho=2$, 3 and 4$\\times 10^7$~g/cm$^3$) and of spherica...

  20. A survey of pulsating DA and DB white dwarfs Observations with the Whole Earth Telescope

    Science.gov (United States)

    Provencal, J. L.; Montgomery, M.; Shipman, H.

    2017-09-01

    White dwarfs represent the end point of stellar evolution for the majority of stars. As such, they are excellent astrophysical laboratories. They are structurally simple, with electron degenerate cores surrounded by thin surface layers of helium and/or hydrogen. The g-mode pulsations provide a window into their internal structure. The Whole Earth Telescope has been conducting a long-term survey of pulsating white dwarfs with the goal of providing an empirical map of convection parameters across the DA and DB instability strips. We present an overview of white dwarf asteroseismology, and discuss the current status of our survey.

  1. Super-Nyquist White Dwarf Pulsations in K2 Long-Cadence Data

    Science.gov (United States)

    Bell, Keaton J.; Hermes, JJ; Montgomery, Michael H.; Vanderbosch, Zach

    2017-06-01

    The Kepler and K2 missions have recently revolutionized the field of white dwarf asteroseismology. Since white dwarfs pulsate on timescales of order 10 minutes, we aim to observe these objects at K2’s short cadence (1 minute). Occasionally we find signatures of pulsations in white dwarf targets that were only observed by K2 at long cadence (30 minute). These signals suffer extreme aliasing since the intrinsic frequencies exceed the Nyquist sampling limit. We present our work to recover accurate frequency determinations for these targets, guided by a limited amount of supplementary, ground-based photometry from McDonald Observatory.

  2. The Large Synoptic Survey Telescope: A summary update on the scientific potential for pulsating star research

    Science.gov (United States)

    Graham, Melissa L.

    2017-09-01

    The Large Synoptic Survey Telescope (LSST) will provide hundreds of deep images of the southern sky over its 10 year duration, enabling variability studies for an unprecedentedly large and unbiased population of objects. In this proceeding paper I will cover the aspects of the LSST's survey and data products that are most relevant to the study of stellar pulsations (Sect. 1), and provide a directory of pertinent materials for further information. I will also summarize the anticipated variable star sample sizes from the LSST, and highlight recent research from several members of the scientific community which evaluates the scientific potential of the LSST's data products with respect to pulsating stars (Sect. 2).

  3. Analysis of Pressure Pulsation Induced by Rotor-Stator Interaction in Nuclear Reactor Coolant Pump

    OpenAIRE

    Zhang, Xu; Wang, Pengfei; Ruan, Xiaodong; Xu, Zhongbin; Fu, Xin

    2017-01-01

    The internal flow of reactor coolant pump (RCP) is much more complex than the flow of a general mixed-flow pump due to high temperature, high pressure, and large flow rate. The pressure pulsation that is induced by rotor-stator interaction (RSI) has significant effects on the performance of pump; therefore, it is necessary to figure out the distribution and propagation characteristics of pressure pulsation in the pump. The study uses CFD method to calculate the behavior of the flow. Results s...

  4. Pulsations of the white dwarf component in V471 tauri-like binaries

    Energy Technology Data Exchange (ETDEWEB)

    Stanghellini, L. (Osservatorio Astronomico di Bologna (Italy)); Cox, A.N. (Los Alamos National Lab., NM (USA)); Starrfield, S.G. (Arizona State Univ., Tempe, AZ (USA). Dept. of Physics and Astronomy Los Alamos National Lab., NM (USA))

    1990-01-01

    The eclipsing spectroscopic binary V471 Tau has a compact DA component that has been observed to pulsate with multimode, low amplitude oscillations. We test three models with different masses (M/M{sub {circle dot}} = 0.6, 0.8, 1.0) against nonradial instability. Our models are derived from an evolutionary track calculated by Iben. The results confirm that the pulsations are driven by the {kappa} and {gamma} mechanisms operating in the ionization zones of carbon and oxygen. 18 refs., 1 fig., 1 tab.

  5. A pulsation phase-dependent dust shell model of OH 26.5 + 0.6

    International Nuclear Information System (INIS)

    Suh, Kyungwon; Jones, T.J.; Bowen, G.H.

    1990-01-01

    The spectral energy distribution of the radio-luminous OH/IR star 26.5 + 0.6 was modeled as a function of pulsation phase, using standard radiative-transfer techniques but with more self-consistent input parameters based partly on pulsation model calculations. The changes in spectral shape and overall intensity are easily explained in terms of the radial movement of the dust condensation radius with the changing luminosity of the star. The derived amplitude of the bolometric light curve is only 1.2 mag, considerably less than expected. 30 refs

  6. A pulsation phase-dependent dust shell model of OH 26.5 + 0.6

    Science.gov (United States)

    Suh, Kyung-Won; Jones, Terry Jay; Bowen, G. H.

    1990-01-01

    The spectral energy distribution of the radio-luminous OH/IR star 26.5 + 0.6 was modeled as a function of pulsation phase, using standard radiative-transfer techniques but with more self-consistent input parameters based partly on pulsation model calculations. The changes in spectral shape and overall intensity are easily explained in terms of the radial movement of the dust condensation radius with the changing luminosity of the star. The derived amplitude of the bolometric light curve is only 1.2 mag, considerably less than expected.

  7. Immediate loading of fixed prostheses in fully edentulous jaws - 1-year follow-up from a single-cohort retrospective study.

    Science.gov (United States)

    Giordano, Francesco; Esposito, Marco

    To evaluate the clinical outcome of four to five implants immediately restored with metal-resin screw-retained cross-arch fixed prostheses in edentulous jaws 1 year after loading. In total, 104 consecutive patients received four 11 × 4.5 mm implants with a torque superior to 35 Ncm. If one implant did not reach a torque superior to 35 Ncm a fifth implant was added. If two implants did not reach a torque superior to 35 Ncm, loading was postponed after 3 months. A total of 127 metal-resin screw-retained fixed prostheses (59 mandibular and 68 maxillary) were to be delivered within 3 days. Outcome measures, evaluated by the treating clinician, were: prosthesis and implant failures, as well as complications. In total, 549 implants were placed (195 immediate post-extractive implants). Twelve maxillary prostheses were delayed loaded, whereas all others were loaded immediately. One year after loading, six patients dropped out, 12 implants failed in eight patients (two patients lost three implants each), and 87 prostheses were remade in 68 patients, one because of three implant failures and then again in the recall programme (replaced twice), one because of tree implant failures and five prosthesis fractures, 10 because of prostheses fractures and 74 in a recall programme for prosthesis replacement. All patients were wearing the planned fixed prostheses at the end of the first year in function. Ninety-eight complications occurred in 66 patients, but all were successfully solved. Immediately loaded cross-arch prostheses supported by four to five implants are a viable therapeutic option, if prostheses are made with resistant frameworks.

  8. Radar detection of a localized 1.4 Hz pulsation in auroral plasma, simultaneous with pulsating optical emissions, during a substorm

    Directory of Open Access Journals (Sweden)

    R. Cosgrove

    2010-10-01

    Full Text Available Many pulsating phenomena are associated with the auroral substorm. It has been considered that some of these phenomena involve kilometer-scale Alfvén waves coupling the magnetosphere and ionosphere. Electric field oscillations at the altitude of the ionosphere are a signature of such wave activity that could distinguish it from other sources of auroral particle precipitation, which may be simply tracers of magnetospheric activity. Therefore, a ground based diagnostic of kilometer-scale oscillating electric fields would be a valuable tool in the study of pulsations and the auroral substorm. In this study we attempt to develop such a tool in the Poker Flat incoherent scatter radar (PFISR. The central result is a statistically significant detection of a 1.4 Hz electric field oscillation associated with a similar oscillating optical emission, during the recovery phase of a substorm. The optical emissions also contain a bright, lower frequency (0.2 Hz pulsation that does not show up in the radar backscatter. The fact that higher frequency oscillations are detected by the radar, whereas the bright, lower frequency optical pulsation is not detected by the radar, serves to strengthen a theoretical argument that the radar is sensitive to oscillating electric fields, but not to oscillating particle precipitation. Although it is difficult to make conclusions as to the physical mechanism, we do not find evidence for a plane-wave-like Alfvén wave; the detected structure is evident in only two of five adjacent beams. We emphasize that this is a new application for ISR, and that corroborating results are needed.

  9. Radar detection of a localized 1.4 Hz pulsation in auroral plasma, simultaneous with pulsating optical emissions, during a substorm

    Science.gov (United States)

    Cosgrove, R.; Nicolls, M.; Dahlgren, H.; Ranjan, S.; Sanchez, E.; Doe, R.

    2010-10-01

    Many pulsating phenomena are associated with the auroral substorm. It has been considered that some of these phenomena involve kilometer-scale Alfvén waves coupling the magnetosphere and ionosphere. Electric field oscillations at the altitude of the ionosphere are a signature of such wave activity that could distinguish it from other sources of auroral particle precipitation, which may be simply tracers of magnetospheric activity. Therefore, a ground based diagnostic of kilometer-scale oscillating electric fields would be a valuable tool in the study of pulsations and the auroral substorm. In this study we attempt to develop such a tool in the Poker Flat incoherent scatter radar (PFISR). The central result is a statistically significant detection of a 1.4 Hz electric field oscillation associated with a similar oscillating optical emission, during the recovery phase of a substorm. The optical emissions also contain a bright, lower frequency (0.2 Hz) pulsation that does not show up in the radar backscatter. The fact that higher frequency oscillations are detected by the radar, whereas the bright, lower frequency optical pulsation is not detected by the radar, serves to strengthen a theoretical argument that the radar is sensitive to oscillating electric fields, but not to oscillating particle precipitation. Although it is difficult to make conclusions as to the physical mechanism, we do not find evidence for a plane-wave-like Alfvén wave; the detected structure is evident in only two of five adjacent beams. We emphasize that this is a new application for ISR, and that corroborating results are needed.

  10. KIC 8262223: A Post-mass Transfer Eclipsing Binary Consisting of a Delta Scuti Pulsator and a Helium White Dwarf Precursor

    Science.gov (United States)

    Guo, Zhao; Gies, Douglas R.; Matson, Rachel A.; García Hernández, Antonio; Han, Zhanwen; Chen, Xuefei

    2017-03-01

    KIC 8262223 is an eclipsing binary with a short orbital period (P = 1.61 day). The Kepler light curves are of Algol-type and display deep and partial eclipses, ellipsoidal variations, and pulsations of δ Scuti type. We analyzed the Kepler photometric data, complemented by phase-resolved spectra from the R-C Spectrograph on the 4 meter Mayall telescope at the Kitt Peak National Observatory and determined the fundamental parameters of this system. The low-mass and oversized secondary ({M}2=0.20{M}⊙ , {R}2=1.31{R}⊙ ) is the remnant of the donor star that transferred most of its mass to the gainer, and now the primary star. The current primary star is thus not a normal δ Scuti star but the result of mass accretion from a lower mass progenitor. We discuss the possible evolutionary history and demonstrate with the MESA evolution code that this system and several other systems discussed in prior literature can be understood as the result of non-conservative binary evolution for the formation of EL CVn-type binaries. The pulsations of the primary star can be explained as radial and non-radial pressure modes. The equilibrium models from single star evolutionary tracks can match the observed mass and radius ({M}1=1.94{M}⊙ , {R}1=1.67{R}⊙ ) but the predicted unstable modes associated with these models differ somewhat from those observed. We discuss the need for better theoretical understanding of such post-mass transfer δ Scuti pulsators.

  11. Immediate loading of two flapless placed mandibular implants supporting cross-arch fixed prostheses: a 3-year follow-up prospective single cohort study.

    Science.gov (United States)

    Cannizzaro, Gioacchino; Felice, Pietro; Boveri, Muriel; Lazzarini, Matteo; Ferri, Vittorio; Leone, Michele; Esposito, Marco

    2014-01-01

    To evaluate the clinical outcome of two implants placed flapless in fully edentulous mandibles and immediately restored with a metal-resin screw-retained cross-arch prostheses 3 years after loading. Eighty consecutively patients were recruited. Implants for immediate loading had to be inserted with a minimum torque of 80 Ncm. Outcome measures, evaluated by two independent assessors, were: prosthesis and implant failures, complications, marginal bone level changes, implant stability quotient (ISQ) values and patient satisfaction. Three years after loading, all prostheses were in function although one patient did not come back for the 1- and 3-year follow-ups. Two implants failed early in two patients, but were successfully replaced and their prostheses remade. Twelve complications occurred in 10 patients but were all successfully treated. After 3 years, mean marginal bone loss was 0.43 mm, mean ISQ values decreased from 75.4 to 75.3, and all but four patients were fully satisfied with the therapy. Four patients were partially satisfied because, lacking molars, they could not chew as they wished. Immediately loaded mandibular cross-arch partial dentures can be supported by only two dental implants up to 3 years. Longer follow-ups (around 10 years) are needed to know the prognosis of this treatment modality.

  12. Deterministic Hydraulic Load Analysis on Reactor Internals of APR1400

    International Nuclear Information System (INIS)

    Kim, Kyu Hyung; Ko, Do Young; Gu, Ja Yeong

    2011-01-01

    The structural integrity of the reactor vessel internals (RVI) of the nuclear power plants that have been constructed should be verified in accordance with the US Nuclear Regulatory Commission Regulatory Guide 1.20 (RG1.20) comprehensive vibration assessment program (CVAP) during preoperational and initial startup testing. The program consists of a vibration and stress analysis, a vibration measurement, an inspection, and an assessment of each program. The vibration and stress analysis program is comprised of a hydraulic load analysis and a structural response analysis. The hydraulic loads include the random hydraulic loads induced by turbulent flow and deterministic hydraulic loads induced by pump pulsation. This paper describes a developed full scope 3-D model and the deterministic hydraulic loads for the RVI of the APR1400

  13. Active power decoupling with reduced converter stress for single ...

    Indian Academy of Sciences (India)

    Single-phase DC–AC power electronic converters suffer from pulsating power at double the line frequency. The commonest practice to handle the issue is to provide a huge electrolytic capacitor for smoothening out the ripple. However, the electrolytic capacitors having short end of lifetime limit the overall lifetime of the ...

  14. Improvement of Torque Production in Single-Phase Induction Motors ...

    African Journals Online (AJOL)

    Existing single phase induction motors exhibit low starting torque. Moreover, during accelerating time and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM ...

  15. Load Measurements

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes Load measurements carried out on a given wind turbine. The aim of the measurement program regarding the loads on the turbine is to verify the basic characteristics of the wind turbine and loads on the blades, the rotor and the tower, using [Ref 1], [Ref2] and [Ref 3]. Regarding...... the fatigue loads, the rotor, blades and tower moments are presented. The fatigue loads are evaluated using rainflow counting described in detail in Ref. [1]. The 1Hz equivalent load ranges are calculated at different wind speeds. All information regarding the instrumentation is collected in [ref 4] and [ref...

  16. ON THE CHALLENGING VARIABILITY OF LS IV-140116: PULSATIONAL INSTABILITIES EXCITED BY THE ε-MECHANISM

    International Nuclear Information System (INIS)

    Miller Bertolami, M. M.; Corsico, A. H.; Althaus, L. G.

    2011-01-01

    We investigate the pulsation driving mechanism responsible for the long-period photometric variations observed in LS IV-14 0 116, a subdwarf B star showing a He-enriched atmospheric composition. To this end, we perform detailed nonadiabatic pulsation computations over fully evolutionary post-He-core-flash stellar structure models, appropriate for hot subdwarf stars at evolutionary phases previous to the He-core burning stage. We found that the variability of LS IV-14 0 116 can be attributed to non-radial g-mode pulsations excited by the ε-mechanism acting in the He-burning shells that appear before the star settles in the He-core burning stage. Even more interestingly, our results show that LS IV-14 0 116 could be the first known pulsating star in which the ε-mechanism of mode excitation is operating. Last but not the least, we find that the period range of destabilized modes is sensitive to the exact location of the burning shell, something that might help in distinguishing between the different evolutionary scenarios proposed for the formation of this star.

  17. Pulsational instability of high-luminosity H-rich pre-white dwarf star

    Science.gov (United States)

    Calcaferro, Leila M.; Córsico, Alejandro H.; Camisassa, María E.; Althaus, Leandro G.; Shibahashi, Hiromoto

    2017-09-01

    We present a pulsational stability analysis on high-luminosity H-rich (DA) white dwarf models evolved from low-metallicity progenitors. We found that the ɛ mechanism due to H-shell burning is able to excite low-order g modes.

  18. Numerical simulation of the pulsating catheter pump : A left ventricular assist device

    NARCIS (Netherlands)

    Verkerke, GJ; Mihaylov, D; Geertsema, AA; Lubbers, J; Rakhorst, G

    1999-01-01

    The pulsating catheter (PUCA) pump, a left ventricular assist device, consists of a hydraulically or pneumatically driven membrane pump, extracorporeally placed and mounted to a valved catheter. The catheter is introduced into an easily accessible artery and positioned with its distal tip in the

  19. Flow-induced pulsations in closed side branches with wet gas

    NARCIS (Netherlands)

    Sanna, F.; Golliard, J.

    2014-01-01

    In a recent paper it has been shown that the presence of liquid has an influence on Flow Induced Pulsations (FIPs) in closed side branches. Even larger effects of liquid in case of whistling in corrugated pipes were reported. For this experimental study, the “Tandem configuration” with two closed

  20. Effect of external pulsation on kinematics of fluid particles in the field ...

    Indian Academy of Sciences (India)

    S Ananth Pai

    utilized to increase mixing characteristics in micro-fluidic devices by using acoustic, electrical or magnetic means. [18]. Effect of external pulsations on the wake behind cir- cular cylinders on vortex shedding behavior has been studied by Lu and Papadakis [19]. The pair of Lamb–Oseen vortices in a fluid move under.

  1. Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

    DEFF Research Database (Denmark)

    Balona, L. A.; Cunha, M. S.; Gruberbauer, M.

    2011-01-01

    Photometry of KIC 10483436 was obtained continuously with 1-min exposures over a 27-d period from the Kepler satellite. The light curve shows rotational variations from surface spots with a period of 4.303 ± 0.002 d, an amplitude of about 6 mmag and eight pulsation frequencies typical of roAp sta...

  2. Diagnostics of high-speed streams and coronal holes using geomagnetic pulsations

    International Nuclear Information System (INIS)

    Bol'shakova, O.V.; Troitskaya, V.A.

    1980-01-01

    In order to study the relations of high-speed solar wind streams and coronal holes analyzed are the parameters of geomagnetic pulsations of the Rs3 type and of high-speed streams at the decrease branch and in the minimum of solar activity. On the basis of the analysis of exciting pulsation regime determined are the differences in characteristics of high-speed stream properties. Presented are the graphical distributions of a number of occurrances of high-speed streams, coronal holes and pure regimes of Rs3R pulsations in several sections of 1973 in the Sun rotations of N1903-1919 and of the change of solar wind velocity while passing through the high-speed streams. It is found that Rs3R occurrance can serve an indicator of the high-speed flux connection with the large equatorial coronal hole. On the basis of the analysis of exciting pulsation properties determined are the differences in the stream characteristics. However the preliminary estimates permit to adopt neither the first nor the second of the existing hypotheses on the sourse of formation of high-speed streams

  3. Discovery of the magnetic field in the pulsating B star β Cephei

    NARCIS (Netherlands)

    Henrichs, H.F.; de Jong, J.A.; Verdugo, E.; Schnerr, R.S.; Neiner, C.; Donati, J.-F.; Catala, C.; Shorlin, S.L.S.; Wade, G.A.; Veen, P.M.; Nichols, J.S.; Damen, E.M.F.; Talavera, A.; Hill, G.M.; Kaper, L.; Tijani, A.M.; Geers, V.C.; Wiersema, K.; Plaggenborg, B.; Rygl, K.L.J.

    2013-01-01

    Context. Although the star itself is not helium enriched, the periodicity and the variability in the UV wind lines of the pulsating B1 IV star β Cephei are similar to what is observed in magnetic helium-peculiar B stars, suggesting that β Cep is magnetic. Aims. We searched for a magnetic field using

  4. Natural convection in square enclosure induced by inner circular cylinder with time-periodic pulsating temperature

    KAUST Repository

    Huang, Zhu

    2015-03-01

    The periodic unsteady natural convection flow and heat transfer in a square enclosure containing a concentric circular cylinder is numerically studied. The temperature of the inner circular cylinder fluctuates periodically with time at higher averaged value while the temperature of the enclosure keeps lower constant, and the natural convection is driven by the temperature difference. The two-dimensional natural convection is simulated with high accuracy temporal spectral method and local radial basis functions method. The Rayleigh number is studied in the range 103 ≤ Ra ≤ 106, the temperature pulsating period ranges from 0.01 to 100 and the temperature pulsating amplitudes are a = 0.5, 1.0 and 1.5. Numerical results reveal that the fluid flow and heat transfer is strongly dependent on the pulsating temperature of inner cylinder. Comparing with the steady state natural convection, the heat transfer is enhanced generally for the time-periodic unsteady natural convection, and the local maximum heat transfer rate is observed for Ra = 105 and 106. Moreover, the phenomenon of backward heat transfer is discussed quantitatively. Also, the influence of pulsating temperature on the unsteady fluid flow and heat transfer are discussed and analyzed.

  5. Cross-Correlation Analysis of UV Profile Variations and Nonradial Pulsations in Be Stars

    Science.gov (United States)

    Gies, Douglas R.

    2001-01-01

    This study is an investigation of the role of photospheric nonradial pulsations in the mass loss processes of Be stars. Some 18 Be stars were the focus of intensive, multi-wavelength campaigns between 1985 and 1996 with the NASA/ESA International Ultraviolet Explorer Satellite (IUE) . The campaigns were designed to monitor variations in the UV flux and stellar wind lines with near simultaneous, high signal-to-noise, optical spectroscopy of photospheric lines. The high quality, ground-based spectra were required to record the subtle, blue-to-red moving bump patterns in spectral line profiles that result from nonradial pulsations. We found that the same fine variations in the UV photospheric lines can be extracted from noisy IUE spectra by cross-correlating each target spectrum with a narrow-lined standard spectrum. Time series analyses of the cross-correlation functions then reveal the periodic signals, amplitudes, phases, and modal identifications of the pulsations. Our goals are to compare such results from UV and optical time series in order to model the stellar photospheric temperature and velocity fluctuations, and to search for correlated UV wind line variations to determine whether there is a connection between pulsation and mass loss.

  6. 76 FR 51876 - Medical Devices; Ophthalmic Devices; Classification of the Eyelid Thermal Pulsation System

    Science.gov (United States)

    2011-08-19

    ... validate electromagnetic compatibility (EMC) and safety of exposure to non-ionizing radiation; (2) Design... HUMAN SERVICES Food and Drug Administration 21 CFR Part 886 Medical Devices; Ophthalmic Devices; Classification of the Eyelid Thermal Pulsation System AGENCY: Food and Drug Administration, HHS. ACTION: Final...

  7. Dose-remission of pulsating electromagnetic fields as augmentation in therapy-resistant depression

    DEFF Research Database (Denmark)

    Straasø, Birgit; Lauritzen, Lise; Lunde, Marianne

    2014-01-01

    OBJECTIVE: To evaluate to what extent a twice daily dose of Transcranial Pulsating ElectroMagnetic Fields (T-PEMF) was superior to once daily in patients with treatment-resistant depression as to obtaining symptom remission after 8 weeks of augmentation therapy. METHODS: A self-treatment set...

  8. Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods

    Energy Technology Data Exchange (ETDEWEB)

    Hora, H. (PS-Division, CERN, CH1211 Geneva 23 (Switzerland)); Aydin, M. (Department of Theoretical Physics, University of New South Wales, Kensington 2033 (Australia))

    1992-04-15

    The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too.

  9. Pulsational instability of high-luminosity H-rich pre-white dwarf star

    Directory of Open Access Journals (Sweden)

    Calcaferro Leila M.

    2017-01-01

    Full Text Available We present a pulsational stability analysis on high-luminosity H-rich (DA white dwarf models evolved from low-metallicity progenitors. We found that the ε mechanism due to H-shell burning is able to excite low-order g modes.

  10. Effect of external pulsation on kinematics of fluid particles in the field ...

    Indian Academy of Sciences (India)

    The effect of external pulsation on a pair of stationary Lamb–Oseen vortices of equal strength has been analyzed to investigate kinematic behavior of a fluid particle. The assumption of vortices being treated stationary or fixed vortex filaments is valid in a reference frame attached to the vortex system with axes along and ...

  11. Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

    Czech Academy of Sciences Publication Activity Database

    Miyoshi, Y.; Oyama, S.; Saito, S.; Kurita, S.; Fujiwara, H.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G.; Santolík, Ondřej; Clilverd, M.; Rodger, C. J.; Turunen, E.; Tsuchiya, F.

    2015-01-01

    Roč. 120, č. 4 (2015), s. 2754-2766 ISSN 2169-9380 Institutional support: RVO:68378289 Keywords : pulsating aurora * EISCAT * Van Allen Probes * pitch angle scattering Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.318, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020690/abstract

  12. Investigation on Characterizing Heated Pulsating Flows with Hot Wire Anemometers - A Hands-On Approach

    Directory of Open Access Journals (Sweden)

    Marius Alexandru PANAIT

    2014-06-01

    Full Text Available The pulsating heated flows are traditionally a difficult subject to treat with conventional hot wire or film methods. Special factors that complicate matters are flow reversal and non linear flow effects of vortices and wire probe wake disturbances on the heat transfer to the hot film or wire sensor in heated pulsating flows. The presence of these strongly nonlinear and unknown terms leads to great difficulties in calibration of hot film probes in this particular regime. The paper analyses the current state of matters in the field and reports a series of solutions that have been practically tested in a case of a high speed pulsated heated flow. Normally such measurements are made in a non-contact fashion using a LDV system or various visualization techniques but there have been recent attempts to use a constant temperature hot wire anemometer system (CTA.To obtain meaningful calibration for hot wire films in hot pulsating flows, a comparison system on other principles (LDV was used, as well as a specially designed nozzle to replace the calibrator unit that could not be operated with heated fluid due to structural integrity reasons. The method as described below works well for the expected speed range that could be generated using the special nozzle.

  13. Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods

    International Nuclear Information System (INIS)

    Hora, H.; Aydin, M.

    1992-01-01

    The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too

  14. Coordinated ground-based and geosynchronous satellite-based measurements of auroral pulsations

    Energy Technology Data Exchange (ETDEWEB)

    Suszcynsky, David M.; Borovsky, Joseph E.; Thomsen, Michelle F.; McComas, David J.; Belian, Richard D.

    1996-09-01

    We describe a technique that uses a ground-based all-sky video camera and geosynchronous satellite-based plasma and energetic particle detectors to study ionosphere-magnetosphere coupling as it relates to the aurora. The video camera system was deployed in Eagle, Alaska for a seven month period at the foot of the magnetic field line that threads geosynchronous satellite 1989-046. Since 1989-046 corotates with the earth, its footprint remains nearly fixed in the vicinity of Eagle, allowing for routine continuous monitoring of an auroral field line at its intersections with the ground and with geosynchronous orbit. As an example of the utility of this technique, we present coordinated ground-based and satellite based observations during periods of auroral pulsations and compare this data to the predictions of both the relaxation oscillator theory and flow cyclotron maser theory for the generation of pulsating aurorae. The observed plasma and energetic particle characteristics at geosynchronous orbit during pulsating aurorae displays are found to be in agreement with the predictions of both theories lending further support that a cyclotron resonance mechanism is responsible for auroral pulsations.

  15. Pressure Pulsations of the Blade Region in S-Shaped Shaft-Extension Tubular Pumping System

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2014-01-01

    Full Text Available The three-dimensional unsteady numerical method is applied to investigate the pressure fluctuation of the S-shaft extension pumping system. Some monitor pointers are set at the key positions of blade region to capture the changing rules of the pressure pulsations, from which the data are collected through time-domain and spectrum analysis. The predicted head and efficiency were validated by the comparison with the tested results, and the comparison result shows that the unsteady flow characteristic of pumping system can be simulated by this method. The pulsating amplitude decreases gradually from blade tip to hub, under the condition of large flow rate for both the inlet and outlet of the impeller, in the way different from the smaller flow rate condition. Through adjusting the impeller rotation speed and the number of blades, the dominant frequency can be controlled. For the same monitor point at the impeller, as the flow coefficient is becoming larger, the pulsating amplitude decreases, in which case, it decreases firstly and then increases between the impeller and the guide vane, and the pulsating amplitude is smallest on the high efficiency condition. The rotation speed of impeller has little effect on the dominant frequency at the outlet of guide vane.

  16. Lattice Boltzmann simulation to laminar pulsating flow past a circular cylinder with constant temperature

    Science.gov (United States)

    Zheng, Youqu; Li, Guoneng; Guo, Wenwen; Dong, Cong

    2017-09-01

    In order to investigate the heat transfer characteristics of pulsating flows past a circular cylinder, a Lattice Boltzmann (LB) numerical code based on a 2-dimension-9-velocity frame is developed. The local Nusselt number and the dimensionless viscous force around the cylinder surface are explored in detail. Double Particle Distribution Function model and the second order extrapolation method for the curve boundary of the cylinder are employed in the LB numerical code. Numerical results found that the spatial averaged Nusselt number of the cylinder is oscillating with the same pulsating frequency of the incoming air flows. The heat transfer enhancement is mainly located in the windward side of the cylinder, and the heat transfer enhancement only happens in one half cycle of the pulsation. Whereas the heat transfer in the leeward side of the cylinder is found to be unaffected, and the heat transfer is slightly deteriorated in the other half cycle of the pulsation. Further analysis showed that the heat transfer enhancement is proportional to the magnitude of dimensionless viscous force.

  17. The effect of the August 11, 1999 total solar eclipse on geomagnetic pulsations

    Czech Academy of Sciences Publication Activity Database

    Střeštík, Jaroslav

    2001-01-01

    Roč. 31, č. 1 (2001), s. 335-338 ISSN 1335-2806. [IAGA Workshop /9./. Hurbanovo, 12.06.2000-18.06.2000] R&D Projects: GA ČR GA205/99/0915 Institutional research plan: CEZ:AV0Z3012916 Keywords : solar eclipse * geomagnetic pulsations * geomagnetic observatories Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  18. Geomagnetic Pc3 pulsations during the total solar eclipse on Aug 11, 1999

    Czech Academy of Sciences Publication Activity Database

    Střeštík, Jaroslav; Prikner, Karel

    2003-01-01

    Roč. 47, č. 3 (2003), s. 565-578 ISSN 0039-3169 R&D Projects: GA ČR GA205/99/0915 Institutional research plan: CEZ:AV0Z3012916 Keywords : geomagnetic pulsations * solar eclipse * MHD waves Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.426, year: 2003

  19. Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?

    Science.gov (United States)

    Corti, M. A.; Kanaan, A.; Córsico, A. H.; Kepler, S. O.; Althaus, L. G.; Koester, D.; Sánchez Arias, J. P.

    2016-03-01

    Context. The discovery of pulsations in low-mass stars opens an opportunity to probe their interiors and determine their evolution by employing the tools of asteroseismology. Aims: We aim to analyse high-speed photometry of SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25 and discover brightness variabilities. In order to locate these stars in the Teff - log g diagram, we fit optical spectra (SDSS) with synthetic non-magnetic spectra derived from model atmospheres. Methods: To carry out this study, we used the photometric data we obtained for these stars with the 2.15 m telescope at CASLEO, Argentina. We analysed their light curves and applied the discrete Fourier transform (FT) to determine the pulsation frequencies. Finally, we compare both stars in the Teff - log g diagram, with two known pre-white dwarfs and seven pulsating pre-ELM white dwarf stars, δ Scuti, and SX Phe stars Results: We report the discovery of pulsations in SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25. We determine their effective temperature and surface gravity to be Teff = 7972 ± 200 K, log g = 4.25 ± 0.5 and Teff = 7925 ± 200 K, log g = 4.25 ± 0.5, respectively. With these parameters, these new pulsating low-mass stars can be identified with either ELM white dwarfs (with ~0.17 M⊙) or more massive SX Phe stars. We identified pulsation periods of 3278.7 and 1633.9 s for SDSS J145847.02+070754.46 and a pulsation period of 3367.1 s for SDSS J173001.94+070600.25. These two new objects, together with those of Maxted et al. (2013, 2014), indicate the possible existence of a new instability domain towards the late stages of evolution of low-mass white dwarf stars, although their identification with SX Phe stars cannot be discarded. Visiting Astronomer, Complejo Astronómico El Leoncito operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

  20. Influence of speed and frequency towards the automotive turbocharger turbine performance under pulsating flow conditions

    International Nuclear Information System (INIS)

    Padzillah, M.H.; Rajoo, S.; Martinez-Botas, R.F.

    2014-01-01

    Highlights: • 3D CFD modeling of a turbocharger turbine with pulsating flow. • Characterization based on turbine speed and frequency. • Speed has higher influence on turbine performance compared to frequency. • Detailed localized flow behavior are shown for better understanding. - Abstract: The ever-increasing demand for low carbon applications in automotive industry has intensified the development of highly efficient engines and energy recovery devices. Even though there are significant developments in the alternative powertrains such as full electric, their full deployment is hindered by high costing and unattractive life-cycle energy and emission balance. Thus powertrain based on highly efficient internal combustion engines are still considered to be the mainstream for years to come. Traditionally, turbocharger has been an essential tool to boost the engine power, however in recent years it is seen as an enabling technology for engine downsizing. It is a well-known fact that a turbocharger turbine in an internal combustion engine operates in a highly pulsating exhaust flow. There are numerous studies looking into the complex interaction of the pulsating exhaust gas within the turbocharger turbine, however the phenomena is still not fully integrated into the design stage. Industry practice is still to design and match the turbine to an engine based on steady performance maps. The current work is undertaken with the mind to move one step closer towards fully integrating the pulsating flow performance into the turbocharger turbine design. This paper presents the development efforts and results from a full 3-D CFD model of a turbocharger turbine stage. The simulations were conducted at 30,000 rpm and 48,000 rpm (50% and 80% design speed respectively) for both 20 Hz and 80 Hz pulsating flow inlet conditions. Complete validation procedure using cold-flow experimental data is also described. The temporal and spatial resolutions of the incidence angle at the

  1. Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star

    Science.gov (United States)

    Holdsworth, Daniel L.; Kurtz, D. W.; Saio, H.; Provencal, J. L.; Letarte, B.; Sefako, R. R.; Petit, V.; Smalley, B.; Thomsen, H.; Fletcher, C. L.

    2018-01-01

    We present a new analysis of the rapidly oscillating Ap (roAp) star, 2MASS J19400781 - 4420093 (J1940; V = 13.1). The star was discovered using SuperWASP broad-band photometry to have a frequency of 176.39 d-1 (2041.55 μHz; P = 8.2 min; Holdsworth et al. 2014a) and is shown here to have a peak-to-peak amplitude of 34 mmag. J1940 has been observed during three seasons at the South African Astronomical Observatory, and has been the target of a Whole Earth Telescope campaign. The observations reveal that J1940 pulsates in a distorted quadrupole mode with unusual pulsational phase variations. A higher signal-to-noise ratio spectrum has been obtained since J1940's first announcement, which allows us to classify the star as A7 Vp Eu(Cr). The observing campaigns presented here reveal no pulsations other than the initially detected frequency. We model the pulsation in J1940 and conclude that the pulsation is distorted by a magnetic field of strength 1.5 kG. A difference in the times of rotational maximum light and pulsation maximum suggests a significant offset between the spots and pulsation axis, as can be seen in roAp stars.

  2. Successful transcatheter closure of coronary artery fistula in a child with single coronary artery: a heavy load and a long road.

    Science.gov (United States)

    Phasalkar, Manjunath; Thakkar, Bhavesh; Poptani, Vishal

    2013-07-01

    Single coronary artery is an uncommon variation of the coronary circulation. After transposition of great arteries, coronary artery fistulas are the most common associated cardiac anomalies in these patients. Transcatheter closure of coronary artery fistula (CAF) involving single coronary artery is a challenging intervention. In the absence of contralateral coronary artery, a complex anatomy of the CAF and a large myocardial perfusion territory of the dominant circulation pose an additional risk during interventional procedure. We report our experience of a successful transcatheter closure of a coronary artery fistula in a patient with single coronary artery. Copyright © 2013 Wiley Periodicals, Inc.

  3. Ulraviolet fluxes and dynamical structure in the pulsating atmosphere of helium star V652 Her

    Science.gov (United States)

    Jeffery, C.

    2016-10-01

    V652 Her is a B-type extreme helium star which pulsates with a period of 154 minutes and a velocity amplitude of 70 km/s. It is believed to have formed from the merger of two helium white dwarfs, and to be the progenitor of a helium-rich hot subdwarf. Its remarkable velocity curve consists of a short shocked acceleration followed by near-ballistic deceleration. Optical spectroscopy has recently resolved dynamical structure within the pulsating photosphere.In contrast, the radius and mass of V652 Her have been measured with a precision seriously limited by sparse low-resolution IUE photometry. To measure the mass to better than +/- 0.1 Msun, constrain the progenitor binary and test the physics of the hydrodynamic pulsation model, a precise measurement of the total flux variation throughout the pulsation cycle is vital.We propose a series of time-resolved HST/STIS ultraviolet observations. These will measure the effective temperature and angular radius with a phase resolution of 0.025 cycles and precision comparable to the velocities provided by recent optical spectroscopy. The shifted and co-added spectrum will explore the surface abundances of iron-group and heavier elements, and hence address questions of origin and evolution. Unleashing the full power of tomography, the dynamical behaviour of the CIV and SiIV absorption lines, formed at optical depths 100 time smaller than the optical helium lines, will be used to explore how pulsations propagate to the outermost layers of the atmosphere and, possibly, into the wind itself.

  4. [Imaging Blood Flow and Pulsation of Retinal Vessels with Full-Field Swept-Source OCT].

    Science.gov (United States)

    Spahr, H; Hillmann, D; Hain, C; Pfäffle, C; Sudkamp, H; Franke, G; Koch, P; Hüttmann, G

    2016-12-01

    Optical coherence tomography (OCT) uses interference to image the retina with high axial resolution. In the last 25 years, new technologies have permitted a steady increase in imaging speed, which made it possible to enlarge the imaged field and to avoid motion artefacts. The speed and precision of retinal imaging is now limited by photodamage of the retina caused by the focused OCT beam and by the speed of the scanning mechanics. Full-field swept-source (FF-SS)-OCT decreases irradiance on the retina and dispenses moving parts by using a camera to acquire the full volume of the retina in parallel. Here we show that FF-SS-OCT is rapid and precise enough to image pulsation in the retina induced by the heart beat. Series of OCT volumes 1.8 × 0.7 mm wide and 1.8 mm deep were recorded in young volunteers over a few cycles of the heart beat. Morphology of the retinal vessels, blood flow and tissue motion as caused by vessel pulsation were calculated from the OCT data. FF-SS-OCT was able to visualise the main structures of the neuronal retina, including vessels and small capillaries and without any motion artefacts. Information on three different dynamic processes was obtained from only one recorded series of OCT volumes: pulsation of blood flow and blood pressure in retinal vessels as well as pulsation of the choroid. Delays between arterial and venous pulse and delay between pulsation in retinal and choroidal vessels were calculated. With a time resolution of 0.5 ms, FF-SS-OCT is able to visualise previously unmeasurably fast changes in the retina, including the propagation of pulse waves. Georg Thieme Verlag KG Stuttgart · New York.

  5. Influence of high-latitude geomagnetic pulsations on recordings of broadband force-balanced seismic sensors

    Directory of Open Access Journals (Sweden)

    E. Kozlovskaya

    2012-08-01

    Full Text Available Seismic broadband sensors with electromagnetic feedback are sensitive to variations of surrounding magnetic field, including variations of geomagnetic field. Usually, the influence of the geomagnetic field on recordings of such seismometers is ignored. It might be justified for seismic observations at middle and low latitudes. The problem is of high importance, however, for observations in Polar Regions (above 60° geomagnetic latitude, where magnitudes of natural magnetic disturbances may be two or even three orders larger. In our study we investigate the effect of ultra-low frequency (ULF magnetic disturbances, known as geomagnetic pulsations, on the STS-2 seismic broadband sensors. The pulsations have their sources and, respectively, maximal amplitudes in the region of the auroral ovals, which surround the magnetic poles in both hemispheres at geomagnetic latitude (GMLAT between 60° and 80°. To investigate sensitivity of the STS-2 seismometer to geomagnetic pulsations, we compared the recordings of permanent seismic stations in northern Finland to the data of the magnetometers of the IMAGE network located in the same area. Our results show that temporary variations of magnetic field with periods of 40–150 s corresponding to regular Pc4 and irregular Pi2 pulsations are seen very well in recordings of the STS-2 seismometers. Therefore, these pulsations may create a serious problem for interpretation of seismic observations in the vicinity of the auroral oval. Moreover, the shape of Pi2 magnetic disturbances and their periods resemble the waveforms of glacial seismic events reported originally by Ekström (2003. The problem may be treated, however, if combined analysis of recordings of co-located seismic and magnetic instruments is used.

  6. Experimental investigation of pulsating heat pipe performance with regard to fuel cell cooling application

    International Nuclear Information System (INIS)

    Clement, Jason; Wang Xia

    2013-01-01

    A pulsating heat pipe (PHP) is a closed loop, passive heat transfer device. Its operation depends on the phase change of a working fluid within the loop. Design and performance testing of a pulsating heat pipe was conducted under conditions to simulate heat dissipation requirements of a proton exchange membrane (PEM) fuel cell stack. Integration of pulsating heat pipes within bipolar plates of the stack would eliminate the need for ancillary cooling equipment, thus also reducing parasitic losses and increasing energy output. The PHP under investigation, having dimensions of 46.80 cm long and 14.70 cm wide, was constructed from 0.3175 cm copper tube. Heat pipes effectiveness was found to be dependent upon several factors such as energy input, types of working fluid and its filling ratio. Power inputs to the evaporator side of the pulsating heat pipe varied from 80 to 180 W. Working fluids tested included acetone, methanol, and deionized water. Filling ratios between 30 and 70 percent of the total working volume were also examined. Methanol outperformed other fluids tested; with a 45 percent fluid fill ratio and a 120 W power input, the apparatus took the shortest time to reach steady state and had one of the smallest steady state temperature differences. The various conditions studied were chosen to assess the heat pipe's potential as cooling media for PEM fuel cells. - Highlights: ► Methanol as a working fluid outperformed both acetone and water in a pulsating heat pipe. ► Performance for the PHP peaked with methanol and a fill ratio of 45 percent fluid to total volume. ► A smaller resistance was associated with a higher power input to the system.

  7. Pulsating aurora and cosmic noise absorption associated with growth-phase arcs

    Directory of Open Access Journals (Sweden)

    D. McKay

    2018-01-01

    Full Text Available The initial stage of a magnetospheric substorm is the growth phase, which typically lasts 1–2 h. During the growth phase, an equatorward moving, east–west extended, optical auroral arc is observed. This is called a growth-phase arc. This work aims to characterize the optical emission and riometer absorption signatures associated with growth-phase arcs of isolated substorms. This is done using simultaneous all-sky camera and imaging riometer observations. The optical and riometric observations allow determination of the location of the precipitation within growth-phase arcs of low- (< 10  keV and high- (>  10 keV energy electrons, respectively. The observations indicate that growth-phase arcs have the following characteristics: 1. The peak of the cosmic noise absorption (CNA arc is equatorward of the optical emission arc. This CNA is contained within the region of diffuse aurora on the equatorward side.2. Optical pulsating aurora are seen in the border region between the diffuse emission region on the equatorward side and the bright growth-phase arc on the poleward side. CNA is detected in the same region. 3. There is no evidence of pulsations in the CNA. 4. Once the equatorward drift starts, it proceeds at constant speed, with uniform separation between the growth-phase arc and CNA of 40 ± 10 km. Optical pulsating aurora are known to be prominent in the post-onset phase of a substorm. The fact that pulsations are also seen in a fairly localized region during the growth phase shows that the substorm expansion-phase dynamics are not required to closely precede the pulsating aurora.

  8. Immediate placement of single implant simultaneously with immediate loading in a fresh socket associated to periapical infection: A clinical case report.

    Science.gov (United States)

    Agustín-Panadero, Rubén; Serra-Pastor, Blanca; Chust-López, Cesar; Fons-Font, Antonio; Ferreiroa, Alberto

    2015-02-01

    Early restoration of the masticatory function, phonatory and aesthetics is some of the current goals of the therapy based on endosseous implants. Facing the classic protocols of implant insertion, which recommend a period of several months between extraction and implant placement, alternatives have been developed that demonstrate that immediate implant placement after tooth extraction permits adequate osseointegration, even in those cases where there is a periapical disease. The immediate restoration of implants after placement is a possibility where aesthetic requirements are high. This article presents a case with immediate implant placement and immediate loading of a first upper premolar with prior periapical pathology due to a vertical fracture. The immediate prosthetic was performed using the extracted crown, which is adapted to be attached to a titanium temporary abutment using a resin cement. After a 4 month healing period work began on the final prosthetic crown. The screw crown was made of zirconium oxide with a covering feldspathic ceramic. At the 12-month follow-up, there were no mechanical or biological complications. The patient gave high satisfaction marks for the overall treatment, giving visual analogue scale score of nine. Immediate post-extraction implants have arisen as an alternative to traditional implants on completely healed bone. Their main aim is to reduce treatment time and number of surgical procedures, along with other objectives such as reduced bone re-absorption and improved aesthetics. Key words:Post-extraction implants, immediate loading prosthetic, implant-retained prosthesis, periapical disease, vertical fracture.

  9. The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

    DEFF Research Database (Denmark)

    Kurtz, Donald W.; Cunha, Margarida S.; Saio, H.

    2011-01-01

    . The principal pulsation mode is an oblique dipole mode that shows a rotationally split frequency septuplet that provides information on the geometry of the mode. The secondary mode also appears to be a dipole mode with a rotationally split triplet, but we are able to show within the improved oblique pulsator...... to these values that reproduces the rotational variations of the two obliquely pulsating modes with different pulsation axes. The star shows overabundances of the rare earth elements, but these are not as extreme as most other roAp stars. The spectrum is variable with rotation, indicating surface abundance...... spotted magnetic variable that shows a complex rotational light variation with a period of Prot= 5.684 59 d. For the first time for any spotted magnetic star of the upper main sequence, we find clear evidence of light variation with a period of twice the rotation period, that is, a subharmonic frequency...

  10. Load forecasting

    International Nuclear Information System (INIS)

    Mak, H.

    1995-01-01

    Slides used in a presentation at The Power of Change Conference in Vancouver, BC in April 1995 about the changing needs for load forecasting were presented. Technological innovations and population increase were said to be the prime driving forces behind the changing needs in load forecasting. Structural changes, market place changes, electricity supply planning changes, and changes in planning objectives were other factors discussed. It was concluded that load forecasting was a form of information gathering, that provided important market intelligence

  11. The Application of Load-cell Technique in the Study of Armour Unit Responses to Impact Loads Tests

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Z.

    1995-01-01

    The slender, complex types of armour units, such as Tetrapods and Dolosse are widely used for rubble mound breakwaters. Many of the recent failures of such structures were caused by unforeseen early breakage of the units, thus revealing an in balance between the strength (structural integrity......) of the units and the hydraulic stability (resistance to displacements) of the armour layers. Breakage is caused by stresses from static, pulsating and impact loads. Impact load generated stresses are difficult to investigate due to non-linear scaling laws. The paper describes a method by which impact loads on....... slender armour units can be studied. by load-cell technique. Moreover, the paper presents DoJos design diagrams for the prediction of both breakage and hydraulic stability...

  12. The Application of Load-cell Technique in the Study of Armour Unit Responses to Impact Loads

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Zhou

    1994-01-01

    The slender, complex types of armour units, such as Tetrapods and Dolosse are widely used for rubble mound breakwaters. Many of the recent failures of such structures were caused by unforeseen early breakage of the units, thus revealing an inbalance between the strength (structural integrity......) of the units and the hydraulic stability (resistance to displacements) of the armour layers. Breakage is caused by stresses from static, pulsating and impact loads. Impact load generated stresses are difficult to investigate due to non-linear scaling laws. The paper describes a method by which impact loads...... on slender armour units can be studied by load-cell technique. Moreover, the paper presents Dolos design diagrams for the prediction of both breakage and hydraulic stability....

  13. Comparing the asteroseismic properties of pulsating extremely low-mass pre-white dwarf stars and δ Scuti stars

    Science.gov (United States)

    Arias, J. P. Sánchez; Córsico, A. H.; Romero, A. D.; Althaus, L. G.

    2017-09-01

    We present the first results of a detailed comparison between the pulsation properties of pulsating Extremely Low-Mass pre-white dwarf stars (the pre-ELMV variable stars) and δ Scuti stars. The instability domains of these very different kinds of stars nearly overlap in the log Teff vs. log g diagram, leading to a degeneracy in the classification of the stars. Our aim is to provide asteroseismic tools for their correct classification.

  14. Comparing the asteroseismic properties of pulsating extremely low-mass pre-white dwarf stars and δ Scuti stars

    Directory of Open Access Journals (Sweden)

    Arias J.P.Sánchez

    2017-01-01

    Full Text Available We present the first results of a detailed comparison between the pulsation properties of pulsating Extremely Low-Mass pre-white dwarf stars (the pre-ELMV variable stars and δ Scuti stars. The instability domains of these very different kinds of stars nearly overlap in the log Teff vs. log g diagram, leading to a degeneracy in the classification of the stars. Our aim is to provide asteroseismic tools for their correct classification.

  15. 40 to 10 Gbit/s demultiplexing using a self-pulsating DFB laser for clock recovery

    DEFF Research Database (Denmark)

    Buxens Azcoaga, Alvaro Juan; Clausen, Anders; Poulsen, Henrik Nørskov

    1998-01-01

    A self-pulsating DFB laser has been used as the clock recovery unit in an OTDM demultiplexing system experiment. Error free demultiplexing from 40 Gb/s to 10 Gb/s is achieved......A self-pulsating DFB laser has been used as the clock recovery unit in an OTDM demultiplexing system experiment. Error free demultiplexing from 40 Gb/s to 10 Gb/s is achieved...

  16. Unusual strong quasi-monochromatic ground Pc5 geomagnetic pulsations in the recovery phase of November 2003 superstorm

    Directory of Open Access Journals (Sweden)

    N. G. Kleimenova

    2005-10-01

    Full Text Available Unusually large-amplitude morning Pc5 magnetic pulsations during the recovery phase of the huge magnetic storm in November 2003 have been studied by using ground-based multi-point observations. Two main spectral Pc5 enhancements were observed: at f≈2 mHz, which featured slowly increasing frequency with decreasing latitude, and at f≈3 mHz, which was latitude independent. The Pc5 pulsations were observed at wide range of latitudes (more than 10° with the same very strong amplitude (up to 500nT and with the same polarization. Only the 3-mHz peak was clearly seen in the spectra of pulsating auroral radio absorption, as observed by the Finnish riometer chain. Short and localized bursts of PiB (f~50–100 mHz magnetic pulsations and simultaneous short bursts of energetic electron precipitation were observed in the morning sector, as well. The beginning of the large-amplitude morning Pc5 activity occurred simultaneously with a substorm onset in the evening and midnight sectors. However, the spectra of pulsations in the morning and evening sectors were different. They were compared with spectra of IMF and solar wind parameters, measured by ACE spacecraft. The similarity between the spectra of morning Pc5 and IMF By was found, but the spectra of evening Pi3 pulsations were similar to the spectra of solar wind density variations. The Pc5 and PiB pulsations, as well as bursts of the auroral radio absorption, suddenly disappeared, when the solar wind density abruptly dropped. We suppose that the ~2-mHz Pc5 geomagnetic pulsations could be attributed to field line resonance (FLR, however, the 3-mHz oscillations were apparently non-resonance origin. Keywords. Magnetospheric physics (MHD waves and instabilities; Solar wind-magnetosphere interaction; Storms and substorms

  17. Unusual strong quasi-monochromatic ground Pc5 geomagnetic pulsations in the recovery phase of November 2003 superstorm

    Directory of Open Access Journals (Sweden)

    N. G. Kleimenova

    2005-10-01

    Full Text Available Unusually large-amplitude morning Pc5 magnetic pulsations during the recovery phase of the huge magnetic storm in November 2003 have been studied by using ground-based multi-point observations. Two main spectral Pc5 enhancements were observed: at f≈2 mHz, which featured slowly increasing frequency with decreasing latitude, and at f≈3 mHz, which was latitude independent. The Pc5 pulsations were observed at wide range of latitudes (more than 10° with the same very strong amplitude (up to 500nT and with the same polarization. Only the 3-mHz peak was clearly seen in the spectra of pulsating auroral radio absorption, as observed by the Finnish riometer chain. Short and localized bursts of PiB (f~50–100 mHz magnetic pulsations and simultaneous short bursts of energetic electron precipitation were observed in the morning sector, as well. The beginning of the large-amplitude morning Pc5 activity occurred simultaneously with a substorm onset in the evening and midnight sectors. However, the spectra of pulsations in the morning and evening sectors were different. They were compared with spectra of IMF and solar wind parameters, measured by ACE spacecraft. The similarity between the spectra of morning Pc5 and IMF By was found, but the spectra of evening Pi3 pulsations were similar to the spectra of solar wind density variations. The Pc5 and PiB pulsations, as well as bursts of the auroral radio absorption, suddenly disappeared, when the solar wind density abruptly dropped. We suppose that the ~2-mHz Pc5 geomagnetic pulsations could be attributed to field line resonance (FLR, however, the 3-mHz oscillations were apparently non-resonance origin.

    Keywords. Magnetospheric physics (MHD waves and instabilities; Solar wind-magnetosphere interaction; Storms and substorms

  18. Crack growth in Fe-2.7 wt% Si single crystals under cyclic loading and 3D atomistic results in bcc iron

    Czech Academy of Sciences Publication Activity Database

    Landa, Michal; Machová, Anna; Uhnáková, Alena; Pokluda, J.; Lejček, Pavel

    2016-01-01

    Roč. 87, June (2016), s. 63-70 ISSN 0142-1123 R&D Projects: GA ČR(CZ) GAP108/10/0698; GA ČR GAP108/12/0144; GA ČR(CZ) GA15-20666S; GA ČR GA13-13616S Institutional support: RVO:61388998 ; RVO:68378271 Keywords : grack growth * cyclic loading * Bcc iron Subject RIV: JL - Materials Fatigue, Friction Mechanics; BM - Solid Matter Physics ; Magnetism (FZU-D) Impact factor: 2.899, year: 2016 http://ac.els-cdn.com/S014211231500448X/1-s2.0-S014211231500448X-main.pdf?_tid=96e3e5a0-fb08-11e5-92cb-00000aab0f02&acdnat=1459845181_19fcdd93d31b1f140714e52b835b33d8

  19. Immediate occlusal loading of single lower molars using Brånemark System Wide-Platform TiUnite implants: an interim report of a prospective open-ended clinical multicenter study.

    Science.gov (United States)

    Calandriello, Roberto; Tomatis, Massimiliano; Vallone, Roberto; Rangert, Bo; Gottlow, Jan

    2003-01-01

    First and second molars in the lower jaw are the most commonly missing teeth. As in other jaw regions with tooth loss, implant therapy is an attractive concept. Owing to the wide dimension of the molar teeth, wide implants seem to be a natural choice. However, wide implants in posterior mandibular regions sometimes present a problem. As an oxidized surface seems to facilitate implant integration and to result in a stronger fixation to bone, it was hypothesized that this surface would improve the performance of wide implants in posterior mandibles. As high initial stability most often is achieved in this region, it was hypothesized that the load per se is not a problem. The purpose of the present study is to evaluate immediate loading of Brånemark System TiUnite Wide-Platform implants (Nobel Biocare AB, Gothenburg, Sweden) supporting single molar crowns in the lower jaw. The study includes 44 patients treated in three separate private dental offices between March 2001 and June 2002. A total of 50 implants were placed, and all implants have passed the 6-month follow-up; 24 have been followed up for 1 year. All implants were provided with provisional crowns in centric occlusion at the time of surgery. No implant has been lost. Marginal bone levels were found in accordance with normal biologic width requirements. Resonance frequency analysis showed high and consistent implant stability. No biomechanical problems were found associated with the use of wide implants, and the potential physiologic problem in dense mandibular bone was eliminated. Although limited by being a short-term study, the result encourages immediate loading of single Brånemark System TiUnite Wide-Platform implants placed in the molar regions in the lower jaw.

  20. Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation.

    Science.gov (United States)

    Straubinger, Rainer; Beyer, Andreas; Volz, Kerstin

    2016-06-01

    A reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa.

  1. Variable Myocardial Response to Load Stresses in Infants with Single Left Ventricular Anatomy: Influence of Initial Physiology and Surgical Palliative Strategy.

    Science.gov (United States)

    Horriat, Narges L; Deatsman, Sara L; Stelter, Jessica; Frommelt, Peter C; Hill, Garick D

    2016-12-01

    Initial surgical strategies in neonates with single left ventricular (LV) anatomy vary based on adequacy of pulmonary and systemic blood flow. Differing myocardial responses to these strategies, as reflected in indices of systolic function, ventricular size, and mass have not been well defined. We sought to evaluate single LV myocardial response to varied physiology and initial palliation and determine whether the response is consistent and predictable. Infants with single LV physiology were divided based on neonatal palliation: no palliation/PA band (NO); BT shunt only (BT); or Norwood procedure (NP). Echo measures were obtained at presentation, early post-bidirectional Glenn (BDG), late post-BDG follow-up, and post-Fontan procedure. Measures included ejection fraction, LV mass indexed to height 2.7 and end diastolic volume indexed to body surface area, and mass/volume ratio. The cohort included 38 children (13 NO, 13 BT, 12 NP). Ejection fraction was similar but depressed in all groups at all stages. LV mass was higher in the NP group than the BT group at early post-BDG (p = 0.03) and higher than both BT and NO groups (p < 0.01) at late post-BDG, but the difference was resolved by post-Fontan follow-up. The NP group had the most remarkable remodeling in LV size from BDG to Fontan, suggesting that volume unloading is most valuable in this subgroup. Ventricular remodeling can be identified by echocardiography in children with single LV physiology, despite variable initial surgical palliative strategies. Importantly, these initial surgical strategies do not result in significant differences after Fontan palliation during early childhood.

  2. Asteroseismology of Pulsating Stars Santosh Joshi∗ & Yogesh C ...

    Indian Academy of Sciences (India)

    a Johnson B filter with continuous 10 s integration. The observations were acquired in a single channel with occasional interruptions to measure the sky background, depending on the phase and position of the moon. To minimize the effects of seeing fluctuations and tracking errors, an aperture of 30′′ was selected.

  3. FUNCTIONS AND REQUIREMENTS FOR RUSSIAN PULSATING MONITOR DEPLOYMENT IN THE GUNITE AND ASSOCIATED TANKS AT OAK RIDGE NATIONAL LABORATORY

    International Nuclear Information System (INIS)

    Thomas Albert

    1999-01-01

    This document provides functions and requirements to support deployment of pulsating mixer pump technology in the Oak Ridge National Laboratory (ORNL) Gunite and Associated Tanks to mobilize and mix the settled sludge and solids in these tanks. In FY 1998 pulsating mixer pump technology, a jet mixer powered by a reciprocating air supply, was selected for FY 1999 deployment in one of the GAAT tanks to mobilize settled solids. Pulsating mixer pump technology was identified in FY 1996 during technical exchanges between the US Department of Energy (DOE) Tanks Focus Area Retrieval and Closure program, the DOE Environmental Management International Programs, and delegates from Russia as a promising technology that could be implemented in the US. The pulsating mixer pump technology, provided by the Russian Integrated Mining Chemical Company, was tested at Pacific Northwest National Laboratory (PNNL) to observe its ability to mobilize settled solids. Based on the results of this demonstration, ORNL and DOE staff determined that a modified pulsating mixer pump would meet project needs for bulk mobilization of Gunite tank sludge prior to deployment of other retrieval systems. The deployment of this device is expected to significantly reduce the costs of operation and maintenance of more expensive retrieval systems. The functions and requirements presented here were developed by evaluating the results and recommendations that resulted from the pulsating mixer pump demonstration at PNNL, and by coupling this with the remediation needs identified by staff at ORNL involved with the remediation of the Gunite and Associated Tanks

  4. Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number

    KAUST Repository

    Yoon, Sung Hwan

    2017-10-12

    According to previous theory, pulsating propagation in a premixed flame only appears when the reduced Lewis number, β(Le-1), is larger than a critical value (Sivashinsky criterion: 4(1 +3) ≈ 11), where β represents the Zel\\'dovich number (for general premixed flames, β ≈ 10), which requires Lewis number Le > 2.1. However, few experimental observation have been reported because the critical reduced Lewis number for the onset of pulsating instability is beyond what can be reached in experiments. Furthermore, the coupling with the unavoidable hydrodynamic instability limits the observation of pure pulsating instabilities in flames. Here, we describe a novel method to observe the pulsating instability. We utilize a thermoacoustic field caused by interaction between heat release and acoustic pressure fluctuations of the downward-propagating premixed flames in a tube to enhance conductive heat loss at the tube wall and radiative heat loss at the open end of the tube due to extended flame residence time by diminished flame surface area, i.e., flat flame. The thermoacoustic field allowed pure observation of the pulsating motion since the primary acoustic force suppressed the intrinsic hydrodynamic instability resulting from thermal expansion. By employing this method, we have provided new experimental observations of the pulsating instability for premixed flames. The Lewis number (i.e., Le ≈ 1.86) was less than the critical value suggested previously.

  5. Signature of the Core Stratification in Pulsating White Dwarfs and Tests of Seismic Inversion

    Science.gov (United States)

    Charpinet, S.; Giammichele, N.; Brassard, P.; Fontaine, G.

    2017-03-01

    We discuss and illustrate how the C/O stratification in the core of white dwarf stars affects their g-mode pulsation spectrum. This effect, mostly occurring through the interplay of partial wave reflection (mode trapping), leaves a subtle but detectable signature, in particular with now available ultra high precision photometry from space, that could be exploited to infer the main structures in this stratification. We provide tests demonstrating that asteroseismology can indeed be used, in some cases, to probe the innermost composition stratification of pulsating white dwarfs. This brings interesting prospects to constrain the core chemical stratification inherited from previous evolutionary phases, which is one of the most uncertain aspect of white dwarf internal structure.

  6. Pulsating-gliding transition in the dynamics of levitating liquid nitorgen droplets.

    Energy Technology Data Exchange (ETDEWEB)

    Snezhko, A.; Jacob, E. B.; Aranson, I. S.; Materials Science Division; Tel-Aviv Univ.

    2008-04-21

    Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets.

  7. Pulsating-gliding transition in the dynamics of levitating liquid nitrogen droplets

    Energy Technology Data Exchange (ETDEWEB)

    Snezhko, Alexey; Aranson, Igor S [Materials Science Division, Argonne National Laboratory, 9700 S Cass Avenue, Argonne, IL 60439 (United States); Jacob, Eshel Ben [School of Physics and Astronomy, 69978 Tel Aviv University, Tel Aviv (Israel)], E-mail: aranson@msd.anl.gov

    2008-04-15

    Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 {sup 0}C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets.

  8. The Large Synoptic Survey Telescope: A summary update on the scientific potential for pulsating star research

    Directory of Open Access Journals (Sweden)

    Graham Melissa L.

    2017-01-01

    Full Text Available The Large Synoptic Survey Telescope (LSST will provide hundreds of deep images of the southern sky over its 10 year duration, enabling variability studies for an unprecedentedly large and unbiased population of objects. In this proceeding paper I will cover the aspects of the LSST’s survey and data products that are most relevant to the study of stellar pulsations (Sect. 1, and provide a directory of pertinent materials for further information. I will also summarize the anticipated variable star sample sizes from the LSST, and highlight recent research from several members of the scientific community which evaluates the scientific potential of the LSST’s data products with respect to pulsating stars (Sect. 2.

  9. γ Doradus pulsation in two pre-main sequence stars discovered by CoRoT

    Science.gov (United States)

    Zwintz, K.; Fossati, L.; Ryabchikova, T.; Kaiser, A.; Gruberbauer, M.; Barnes, T. G.; Baglin, A.; Chaintreuil, S.

    2013-02-01

    Context. Pulsations in pre-main sequence stars have been discovered several times within the last years. But nearly all of these pulsators are of δ Scuti-type. γ Doradus-type pulsation in young stars has been predicted by theory, but lack observational evidence. Aims: We present the investigation of variability caused by rotation and (γ Doradus-type) pulsation in two pre-main sequence members of the young open cluster NGC 2264 using high-precision time series photometry from the CoRoT satellite and dedicated high-resolution spectroscopy. Methods: The variability found using the CoRoT data was combined with the fundamental parameters and chemical abundances derived from high-resolution spectroscopy, obtained at the Mc Donald Observatory, to discuss the presence of pulsation and rotation in the two NGC 2264 cluster members. Time series photometry of NGC 2264 VAS 20 and NGC 2264 VAS 87 was obtained by the CoRoT satellite during the dedicated short run SRa01 in March 2008. NGC 2264 VAS 87 was re-observed by CoRoT during the short run SRa05 in December 2011 and January 2012. Frequency analysis was conducted using Period04 and SigSpec. The spectral analysis was performed using equivalent widths and spectral synthesis. Results: The frequency analysis yielded ten (NGC 2264 VAS 20) and fourteen (NGC 2264 VAS 87) intrinsic frequencies in the range from 0 to 1.5 d-1, which are attributed to be caused by a combination of rotation and pulsation. The effective temperatures were derived to be 6380 ± 150 K for NGC 2264 VAS 20 and 6220 ± 150 K for NGC 2264 VAS 87. Membership of the two stars to the cluster is confirmed independently using X-ray fluxes, radial velocity measurements, and proper motions available in the literature. The derived lithium abundances of log n(Li) = 3.34 and 3.54 for NGC 2264 VAS 20 and NGC 2264 VAS 87 agree with the lithium abundance for other stars in NGC 2264 of similar Teff reported in the literature. Conclusions: We conclude that the two objects

  10. Using internal jugular pulsations as a manometer for right atrial pressure measurements.

    Science.gov (United States)

    Constant, J

    2000-01-01

    External jugulars are not reliable as an indication of right atrial pressure because of their passage through two right angles and also because they are often not visible. The top level of internal jugular pulsations which are transmitted to the skin of the neck serves as a pulsation manometer. A standard chest angle of 45 degrees and a standard zero at the sternal angle can be used together with a centimeter ruler to give a useful measurement of jugular venous pressure. The use of a carpenter level (spirit level) and a round-bottomed tongue blade measured off in centimeters will allow accurate follow-up. An increase in tone-volume can be detected by the abdominal compression test or abdominojugular test (also known by the outdated terminology of hepatojugular reflux). Copyright 2000 S. Karger AG, Basel

  11. TURNING THE PULSATING FLOW INTO LAMINAR FLOW, REDUCTION / ELIMINATION OF EFFECT OF VACUUM, NEW CONSTRUCTIVE SOLUTIONS

    Directory of Open Access Journals (Sweden)

    STANCIU Alexandru Lucian

    2017-05-01

    Full Text Available The article, as a new concept, analyzes the notion of « pulsating flow », the physical phenomenon seen when emptying bottles of PET or Tetra Pak; which do not have a disposal system of the vacuum created while emptying them, situation in which the fluid stream becomes oscillating in terms of the speed and the flow of the fluid passing through the drain area / section. Pulsating flow is a result of the vacuum created in the container, as opposed to laminar and turbulent flow whose existence is determined by the relative speed of the layers of fluid and the friction forces [2]. In the paper I present some new constructive solutions, designed by AutoCAD and created physically with rapid-prototyping

  12. One abutment-one time versus a provisional abutment in immediately loaded post-extractive single implants: a 1-year follow-up of a multicentre randomised controlled trial.

    Science.gov (United States)

    Grandi, Tommaso; Guazzi, Paolo; Samarani, Rawad; Maghaireh, Hassan; Grandi, Giovanni

    2014-01-01

    To compare immediately loaded post-extractive single implants using a definitive abutment versus provisional abutment later replaced by custom-made abutment. In two private clinics, 28 patients in need of one single post-extractive implant in the maxilla or mandible from the left second premolar to the right second premolar area were randomised shortly before tooth extraction to provisional abutment (PA) and definitive abutment (DA) groups. Three patients had to be excluded for buccal wall fracture after tooth extraction. In the PA group, implants were immediately restored using a platform-switched provisional titanium abutment and definitive platform-switched titanium abutments were used in the DA group. In both groups, a non-occluding provisional single crown was provided. Implants were definitively restored after 4 months. In the PA group, the abutment was removed and the impression was made directly on the implant platform. In the DA group an impression of the abutment was made using a retraction cord. Outcome measures were: implant failures; complications; and marginal peri-implant bone level changes. Patients were followed up to 1 year after loading. Twelve patients were randomised to the DA group and 13 patients to the PA group. At the 12-month follow-up, no implant failed. One biological complication occurred in the DA group and one mechanical complication occurred in the PA group. All complications were successfully treated. One year after loading, implants in the DA group lost an average of 0.11 mm (SD: 0.06) of periimplant bone and implants in PA group about 0.58 mm (SD: 0.11). At the 12-month follow-up, there was a statistically significant difference in bone level change between groups (mean difference: 0.48 mm, CI 95% 0.40; 0.55, P < 0.0001). Within the limits of this study, the non-removal of abutments placed at the time of surgery resulted in the maintenance of 0.5 mm more bone levels around immediately restored postextractive single implants than

  13. Pulsating strings from two-dimensional CFT on (T4N/S(N

    Directory of Open Access Journals (Sweden)

    Carlos Cardona

    2015-04-01

    Full Text Available We propose a state from the two-dimensional conformal field theory on the orbifold (T4N/S(N as a dual description for a pulsating string moving in AdS3. We show that, up to first order in the deforming parameter, the energy in both descriptions has the same dependence on the mode number, but with a non-trivial function of the coupling.

  14. Pitch angle scattering and particle precipitation in a pulsating aurora - an experimental study

    International Nuclear Information System (INIS)

    Sandahl, I.

    1984-10-01

    A pulsating aurora occurring during the recovery phase of a substorm on January 27, 1979 was monitored by a large set of instruments. The Swedish sounding rocket S23-L2 was launched at magnetic midnight over pulsating patches, some of which exhibited 3+-1 Hz modulation. The ground based instrumentation included auroral TV cameras, all sky cameras, photometers and magnetometers. The geostationary satellite GEOS-2 was located in the equatorial plane, approximately conjugate to the rocket. The central experiment of this study is the particle experiment on the rocket. Several aspects of pulsating auroras have been investigated. The auroral luminosity variations were very well correlated to variations in the flux of precipitating hot electrons. The 1-20 second pulsations were caused by increased fluxes of 4-40 keV electrons. The 3+-1 Hz modulation was detected in 7-200 keV electrons, but the biggest energy flux modulation occurred for electrons of about 60 keV. Model calculations involving the electron distributions measured by the sounding rocket and GEOS-2, consistently show that the electrons may have been scattered into the loss cone through the Doppler shifted gyroresonance with whistler mode waves. The scattering was not a pure pitch angle scattering as in the classical Coroniti and Kennel theory, but involved also a systematic energy loss from the particles. The waves were probably hiss with some chorus elements. The equatorial plane plasma density was estimated in two independent ways to be about 2x10 6 m- 3 . The 3+-1 Hz modulation was measured both by the particle experiment on the rocket and by the wave experiment on GEOS-2. Properties of the modulated fluxes are described and a qualitative model for the cause of the modulation is proposed. (author)

  15. Experimental in-vitro bone cements disintegration with ultrasonic pulsating water jet for revision arthroplasty

    Czech Academy of Sciences Publication Activity Database

    Hloch, Sergej; Foldyna, Josef; Pude, F.; Kloc, J.; Zeleňák, Michal; Hvizdoš, P.; Monka, P.; Smolko, I.; Ščučka, Jiří; Kozak, D.; Sedmak, A.; Mihalčinová, E.

    2015-01-01

    Roč. 22, č. 6 (2015), s. 1609-1616 ISSN 1330-3651 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : bone cement * revision arthroplasty * ultrasonic pulsating water jet Subject RIV: JQ - Machines ; Tools Impact factor: 0.464, year: 2015 http://www.tehnicki-vjesnik.com/web/public/archive

  16. Eternal and pulsating universes in Einstein-Cartan space-time

    Science.gov (United States)

    Assad, M. J. D.; Romero, C.

    1992-05-01

    A class of closed (Bianchi type IX), homogeneous and isotropic universes generated by an unpolarized spinning perfect fluid on the basis of Einstein-Cartan theory is presented. The models are nonsingular and pulsate around a static configuration in an endless number of cycles. All of them undergo periodic phases of accelerated (inflationary) expansion and may be reduced to the dynamics of an anharmonic oscillator.

  17. Energetic particle counterparts for geomagnetic pulsations of Pc1 and IPDP types

    Directory of Open Access Journals (Sweden)

    T. A. Yahnina

    2003-12-01

    Full Text Available Using the low-altitude NOAA satellite particle data, we study two kinds of localised variations of energetic proton fluxes at low altitude within the anisotropic zone equatorward of the isotropy boundary. These flux variation types have a common feature, i.e. the presence of precipitating protons measured by the MEPED instrument at energies more than 30 keV, but they are distinguished by the fact of the presence or absence of the lower-energy component as measured by the TED detector on board the NOAA satellite. The localised proton precipitating without a low-energy component occurs mostly in the morning-day sector, during quiet geomagnetic conditions, without substorm injections at geosynchronous orbit, and without any signatures of plasmaspheric plasma expansion to the geosynchronous distance. This precipitation pattern closely correlates with ground-based observations of continuous narrow-band Pc1 pulsations in the frequency range 0.1–2 Hz (hereafter Pc1. The precipitation pattern containing the low energy component occurs mostly in the evening sector, under disturbed geomagnetic conditions, and in association with energetic proton injections and significant increases of cold plasma density at geosynchronous orbit. This precipitation pattern is associated with geomagnetic pulsations called Intervals of Pulsations with Diminishing Periods (IPDP, but some minor part of the events is also related to narrow-band Pc1. Both Pc1 and IPDP pulsations are believed to be the electromagnetic ion-cyclotron waves generated by the ion-cyclotron instability in the equatorial plane. These waves scatter energetic protons in pitch angles, so we conclude that the precipitation patterns studied here are the particle counterparts of the ion-cyclotron waves.Key words. Ionosphere (particle precipitation – Magnetospheric physics (energetic particles, precipitating – Space plasma physics (wave-particle interactions

  18. Load Balancing Scientific Applications

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, Olga Tkachyshyn [Texas A & M Univ., College Station, TX (United States)

    2014-12-01

    The largest supercomputers have millions of independent processors, and concurrency levels are rapidly increasing. For ideal efficiency, developers of the simulations that run on these machines must ensure that computational work is evenly balanced among processors. Assigning work evenly is challenging because many large modern parallel codes simulate behavior of physical systems that evolve over time, and their workloads change over time. Furthermore, the cost of imbalanced load increases with scale because most large-scale scientific simulations today use a Single Program Multiple Data (SPMD) parallel programming model, and an increasing number of processors will wait for the slowest one at the synchronization points. To address load imbalance, many large-scale parallel applications use dynamic load balance algorithms to redistribute work evenly. The research objective of this dissertation is to develop methods to decide when and how to load balance the application, and to balance it effectively and affordably. We measure and evaluate the computational load of the application, and develop strategies to decide when and how to correct the imbalance. Depending on the simulation, a fast, local load balance algorithm may be suitable, or a more sophisticated and expensive algorithm may be required. We developed a model for comparison of load balance algorithms for a specific state of the simulation that enables the selection of a balancing algorithm that will minimize overall runtime.

  19. Two-phase ultraviolet spectrophotometry of the pulsating white dwarf ZZ Piscium

    Science.gov (United States)

    Bond, H. E.; Kemper, E.; Grauer, A. D.; Holm, A. V.; Panek, R. J.; Schiffer, F. H., III

    1985-01-01

    Spectra of the pulsating white dwarf ZZ Psc (= G29-38) were obtained using the International Ultraviolet Explorer. By using a multiple-exposure technique in conjunction with simultaneous ground-based exposure-metering photometry, it was possible to obtain mean on-pulse and off-pulse spectra in the 1950-1310 A wavelength range. The ratio of the time-averaged on-pulse to off-pulse spectra is best fitted by a temperature variation that is in phase with the optical light variation. This result is consistent with the hypothesis that the observed variation is due to a high-order nonradial pulsation. Conventional ultraviolet spectra of ZZ Psc showed broad absorption features at 1390 and 1600 A. These features are also found in the spectra of the cool DA-type white dwarfs G226-29 and G67-23, and appear to increase in strength with decreasing temperature. A possible explanation for the 1600 A feature is absorption by the satellite band of resonance-broadened hydrogen Ly-alpha. Such absorption would also help explain a discrepancy between the observed pulsation amplitude shortward of 1650 A and the predicted amplitudes based on model atmospheres.

  20. On the relevance of source effects in geomagnetic pulsations for induction soundings

    Science.gov (United States)

    Neska, Anne; Tadeusz Reda, Jan; Leszek Neska, Mariusz; Petrovich Sumaruk, Yuri

    2018-03-01

    This study is an attempt to close a gap between recent research on geomagnetic pulsations and their usage as source signals in electromagnetic induction soundings (i.e., magnetotellurics, geomagnetic depth sounding, and magnetovariational sounding). The plane-wave assumption as a precondition for the proper performance of these methods is partly violated by the local nature of field line resonances which cause a considerable portion of pulsations at mid latitudes. It is demonstrated that and explained why in spite of this, the application of remote reference stations in quasi-global distances for the suppression of local correlated-noise effects in induction arrows is possible in the geomagnetic pulsation range. The important role of upstream waves and of the magnetic equatorial region for such applications is emphasized. Furthermore, the principal difference between application of reference stations for local transfer functions (which result in sounding curves and induction arrows) and for inter-station transfer functions is considered. The preconditions for the latter are much stricter than for the former. Hence a failure to estimate an inter-station transfer function to be interpreted in terms of electromagnetic induction, e.g., because of field line resonances, does not necessarily prohibit use of the station pair for a remote reference estimation of the impedance tensor.