The effect of diffusive nuclear burning in neutron star envelopes on cooling in accreting systems

M J P Wijngaarden; Wynn C G Ho; Philip Chang; Dany Page; Rudy Wijnands; Laura S Ootes; Andrew Cumming; Nathalie Degenaar; Mikhail Beznogov

doi:10.1093/mnras/staa595

The effect of diffusive nuclear burning in neutron star envelopes on cooling in accreting systems

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa595 ◽

2020 ◽

Vol 493 (4) ◽

pp. 4936-4944

Author(s):

M J P Wijngaarden ◽

Wynn C G Ho ◽

Philip Chang ◽

Dany Page ◽

Rudy Wijnands ◽

...

Keyword(s):

Neutron Star ◽

Thermal Evolution ◽

Theoretical Models ◽

Light Elements ◽

Heating Source ◽

Total Luminosity ◽

Deep Interior ◽

Nuclear Burning ◽

Short Time ◽

Over Time

ABSTRACT Valuable information about the neutron star (NS) interior can be obtained by comparing observations of thermal radiation from a cooling NS crust with theoretical models. Nuclear burning of lighter elements that diffuse to deeper layers of the envelope can alter the relation between surface and interior temperatures and can change the chemical composition over time. We calculate new temperature relations and consider two effects of diffusive nuclear burning (DNB) for H–C envelopes. First, we consider the effect of a changing envelope composition and find that hydrogen is consumed on short time-scales and our temperature evolution simulations correspond to those of a hydrogen-poor envelope within ∼100 d. The transition from a hydrogen-rich to a hydrogen-poor envelope is potentially observable in accreting NS systems as an additional initial decline in surface temperature at early times after the outburst. Second, we find that DNB can produce a non-negligible heat flux, such that the total luminosity can be dominated by DNB in the envelope rather than heat from the deep interior. However, without continual accretion, heating by DNB in H–C envelopes is only relevant for <1–80 d after the end of an accretion outburst, as the amount of light elements is rapidly depleted. Comparison to crust cooling data shows that DNB does not remove the need for an additional shallow heating source. We conclude that solving the time-dependent equations of the burning region in the envelope self-consistently in thermal evolution models instead of using static temperature relations would be valuable in future cooling studies.

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Thermal evolution and quiescent emission of transiently accreting neutron stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936003 ◽

2019 ◽

Vol 629 ◽

pp. A88 ◽

Cited By ~ 11

Author(s):

A. Y. Potekhin ◽

A. I. Chugunov ◽

G. Chabrier

Keyword(s):

Neutron Star ◽

Neutron Stars ◽

Nuclear Reactions ◽

Thermal Evolution ◽

Theoretical Models ◽

Equilibrium Temperature ◽

Theoretical Interpretation ◽

Quasi Equilibrium ◽

Accretion Rates

Aims. We study the long-term thermal evolution of neutron stars in soft X-ray transients (SXTs), taking the deep crustal heating into account consistently with the changes of the composition of the crust. We collect observational estimates of average accretion rates and thermal luminosities of such neutron stars and compare the theory with observations. Methods. We performed simulations of thermal evolution of accreting neutron stars, considering the gradual replacement of the original nonaccreted crust by the reprocessed accreted matter, the neutrino and photon energy losses, and the deep crustal heating due to nuclear reactions in the accreted crust. We also tested and compared results for different modern theoretical models. We updated a compilation of the observational estimates of the thermal luminosities in quiescence and average accretion rates in the SXTs and compared the observational estimates with the theoretical results. Results. The long-term thermal evolution of transiently accreting neutron stars is nonmonotonic. The quasi-equilibrium temperature in quiescence reaches a minimum and then increases toward the final steady state. The quasi-equilibrium thermal luminosity of a neutron star in an SXT can be substantially lower at the minimum than in the final state. This enlarges the range of possibilities for theoretical interpretation of observations of such neutron stars. The updates of the theory and observations leave the previous conclusions unchanged, namely that the direct Urca process operates in relatively cold neutron stars and that an accreted heat-blanketing envelope is likely present in relatively hot neutron stars in the SXTs in quiescence. The results of the comparison of theory with observations favor suppression of the triplet pairing type of nucleon superfluidity in the neutron-star matter.

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Nuclear equation of state and neutron star cooling

International Journal of Modern Physics E ◽

10.1142/s021830131750015x ◽

2017 ◽

Vol 26 (04) ◽

pp. 1750015 ◽

Cited By ~ 14

Author(s):

Yeunhwan Lim ◽

Chang Ho Hyun ◽

Chang-Hwan Lee

Keyword(s):

Neutron Star ◽

Equation Of State ◽

Neutron Stars ◽

Nuclear Matter ◽

Thermal Evolution ◽

Observation Data ◽

Nuclear Equation Of State ◽

The Core ◽

Dense Nuclear Matter ◽

Nuclear Models

In this paper, we investigate the cooling of neutron stars with relativistic and nonrelativistic models of dense nuclear matter. We focus on the effects of uncertainties originated from the nuclear models, the composition of elements in the envelope region, and the formation of superfluidity in the core and the crust of neutron stars. Discovery of [Formula: see text] neutron stars PSR J1614−2230 and PSR J0343[Formula: see text]0432 has triggered the revival of stiff nuclear equation of state at high densities. In the meantime, observation of a neutron star in Cassiopeia A for more than 10 years has provided us with very accurate data for the thermal evolution of neutron stars. Both mass and temperature of neutron stars depend critically on the equation of state of nuclear matter, so we first search for nuclear models that satisfy the constraints from mass and temperature simultaneously within a reasonable range. With selected models, we explore the effects of element composition in the envelope region, and the existence of superfluidity in the core and the crust of neutron stars. Due to uncertainty in the composition of particles in the envelope region, we obtain a range of cooling curves that can cover substantial region of observation data.

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The Thermal Evolution following a Superburst on an Accreting Neutron Star

The Astrophysical Journal ◽

10.1086/382873 ◽

2004 ◽

Vol 603 (1) ◽

pp. L37-L40 ◽

Cited By ~ 52

Author(s):

Andrew Cumming ◽

Jared Macbeth

Keyword(s):

Neutron Star ◽

Thermal Evolution

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What Influences Customer Satisfaction When? Product and Service Over Time

Journal of Management Research ◽

10.5296/jmr.v8i3.9538 ◽

2016 ◽

Vol 8 (3) ◽

pp. 45 ◽

Cited By ~ 1

Author(s):

Shueh-Chin Ting

Keyword(s):

Customer Satisfaction ◽

Service Performance ◽

Customer Relationship ◽

Long Time ◽

Curvilinear Relationships ◽

Short Time ◽

Time Frames ◽

Post Purchase ◽

Product Weight ◽

Over Time

Though researchers have examined the changes in the effects of product and service performance on customer satisfaction, the short time frames of most studies prevents deeper understanding of this relationship. This study collects information from pre-purchase to 15 years post-purchase from 11,056 potential and existing automobile customers in the Taiwan market. The data is analyzed by a regression model. Results reveal that the importance of both product and service performance change over long time and the long-term trends of product and service performance weights are non-linear. In addition, from pre-purchase to the second year post-purchase, service weight is higher than product weight, but after the third year, product weight exceeds service weight. Product and service weight on customer satisfaction over time exhibit curvilinear relationships. Therefore, which one of product or service a company should stress depends on the stage in the customer relationship.

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Trender i insidens og mortalitet av kreft i Norge

Norsk Epidemiologi ◽

10.5324/nje.v11i2.554 ◽

2009 ◽

Vol 11 (2) ◽

Author(s):

Steinar Tretli ◽

Trude Eid Robsahm ◽

Elisabeth Svensson

Keyword(s):

Case Fatality ◽

English Summary ◽

Classification Rules ◽

Font Size ◽

Treatment Results ◽

Mortality Trends ◽

Calendar Time ◽

Incidence And Mortality ◽

Short Time ◽

Over Time

ENGLISH SUMMARYTretli S, Robsahm TE, Svensson E. Time trends in cancer incidence and mortality in Norway.Nor J Epidemiol 2001; 11 (2): 177-185.The aim of this study is to decribe the trends in incidence and mortality of cancer by calendar time.Most types of cancer, except those with high case fatality short time after the diagnosis, demonstrate alarger increase in incidence than in mortality over time. For persons below 70 years of age during theperiod 1931-95 the mortality rate has been close to constant. Obviously, the mortality of lung andstomach cancer has changed over time, however, these have changed in different direction and almostlevelled out. In this paper, it is discussed how registration routines, classification rules, treatment resultsand the basis of the diagnosis can influence the incidence and mortality trends.

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Do organizations learn? Results of a Hungarian longitudinal school-research program

Opus et Educatio ◽

10.3311/ope.473 ◽

2021 ◽

Vol 8 (3) ◽

Author(s):

Tamás Kersánszki ◽

Tibor Baráth ◽

Ágnes Fazekas

Keyword(s):

Student Achievement ◽

Knowledge Sharing ◽

Learning Organization ◽

Research Program ◽

Quantitative Data ◽

Longitudinal Research ◽

Theoretical Models ◽

Organization Model ◽

School Research ◽

Over Time

Our study was based on the results of longitudinal research conducted between 2015 and 2021, which examined the schools learning organizations and sought to answer the question of what factors may be most decisive in the operation of schools that can effectively support student achievement, and how they change over time. After describing the theoretical models describing the learning organization of schools, the correlations of quantitative data and models and their five-year change are analyzed.It is clear from the data that educators and leaders see shared goals and a vision, and a willingness to take risks and innovate as the most advanced. There is a lack of responsibility and a collaborative atmosphere, and a dimension of knowledge sharing and partnerships. The shift in primary variables and more advanced statistical analyzes predict the emergence of newer learning organization model alternatives that can more accurately describe changes and areas of learning organization dimensions.

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IMPROVEMENT OF THE ROUGHNESS FORECASTING MODEL OF COATING OF NON-RIGID ROAD PAVEMENT COATING

Municipal economy of cities ◽

10.33042/2522-1809-2021-4-164-71-76 ◽

2021 ◽

Vol 4 (164) ◽

pp. 71-76

Author(s):

A. Batrakova ◽

H. Sarkisian ◽

E. Zakharova

Keyword(s):

Experimental Data ◽

Service Life ◽

Pearson Correlation ◽

Safety Margin ◽

Calculated Data ◽

Statistical Processing ◽

Theoretical Models ◽

Rigid Pavement ◽

Improved Model ◽

Over Time

To ensure safe, comfortable driving at high speeds, a strong, even surface is required for the entire life of the pavement. In this regard, the issue of predicting changes in the equality of coverage over time is very important. The article considers the peculiarities of changing the longitudinal equality of the road surface. Purpose is to improve the model of forecasting the equality of non-rigid pavement. Methods – analytical and experimental. The analysis of existing decisions on the issue of forecasting the equality of coverage is performed. The most important factors influencing the change in the equality of road coverage have been identified. Based on the analysis of theoretical models and a number of experimental data, an improved model for predicting the equality of coverage of non-rigid pavement is proposed. MathCAD and MS Excel were involved in the development of an improved model that takes into account the most important factors. The model of change of coverage roughness, where increase in the roughness index over time is considered as a function of such parameters, is improved: the modulus of pavement elasticity (actual or required); the number of load cycles for t years of pavement operation; the share of trucks in the traffic flow; the factor of safety margin of the pavement structure. The adequacy of the developed model of changing the roughness of coverage is confirmed by statistical processing of experimental data obtained by the thesis author and other researchers on public roads with different service life, and calculated data under the theoretical model. The Pearson correlation coefficient between experimental and calculated data is more than 0.95, which indicates the adequacy of the developed model. Compared to the well-known models of forecasting coverage roughness, the improved model allows to apply a wider range of values of the general equivalent modulus of elasticity of pavement design (from 100 MPa to 600 MPa) and to receive forecast values of roughness for service life of non-rigid pavement over 5 years.

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383. Feasibility of Specimen Self-collection in Young Children Undergoing SARS-CoV-2 Surveillance for In-person Learning

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab466.584 ◽

2021 ◽

Vol 8 (Supplement_1) ◽

pp. S293-S293

Author(s):

Jonathan Altamirano ◽

Grace Tam ◽

Marcela Lopez ◽

India Robinson ◽

Leanne Chun ◽

...

Keyword(s):

Young Children ◽

Time Window ◽

School Administrators ◽

Error Rates ◽

Independent Observer ◽

Specimen Collection ◽

Timing Data ◽

Short Time Window ◽

Short Time ◽

Over Time

Abstract Background While pediatric cases of COVID-19 are at low risk for adverse events, schoolchildren should be considered for surveillance as they can become infected at school and serve as sources of household or community transmission. Our team assessed the feasibility of young children self-collecting SARS-CoV-2 samples for surveillance testing in an educational setting. Methods Students at a K-8 school were tested weekly for SARS-CoV-2 from September 2020 - June 2021. Error rates were collected from September 2020 - January 2021. Clinical staff provided all students with instructions for anterior nares specimen self-collection and then observed them to ensure proper technique. Instructions included holding the sterile swab while making sure not to touch the tip, inserting the swab into their nostril until they start to feel resistance, and rubbing the swab in four circles before repeating the process in their other nostril. An independent observer timed random sample self-collections from April - June 2021. Results 2,590 samples were collected from 209 students during the study period when data on error rates were collected. Errors occurred in 3.3% of all student encounters (n=87). Error rates over time are shown in Figure 1, with the highest rate occurring on the first day of testing (n=20/197, 10.2%) and the lowest in January 2021 (n=1/202, 0.5%). 2,574 visits for sample self-collection occurred during the study period when independent timing data was collected (April - June 2021). Of those visits, 7.5% (n=193) were timed. The average duration of each visit was 70 seconds. Figure 1. Swab Error Rates Over Time Conclusion Pediatric self-collected lower nasal swabs are a viable and easily tolerated specimen collection method for SARS-CoV-2 surveillance in school settings, as evidenced by the low error rate and short time window of sample self-collection during testing. School administrators should expect errors to drop quickly after implementing testing. Disclosures All Authors: No reported disclosures

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Active Optimum Control of Orthotropic Plates Using Piezoelectric Stiffeners

14th Biennial Conference on Mechanical Vibration and Noise: Intelligent Structures, Materials, and Vibrations ◽

10.1115/detc1993-0157 ◽

1993 ◽

Author(s):

Victor Birman ◽

Sarp Adali

Keyword(s):

Time Interval ◽

Short Time Interval ◽

Bending Moments ◽

Optimum Control ◽

Orthotropic Plates ◽

Time Intervals ◽

Control Forces ◽

Short Time ◽

Alternating Voltage ◽

Over Time

Abstract Active control of orthotropic plates subjected to an impulse loading is considered. The dynamic response is minimized using in-plane forces or bending moments induced by piezoelectric stiffeners bonded to the opposite surfaces of the plate and placed symmetrically with respect to the middle plane. The control forces and moments are activated by a piece-wise constant alternating voltage with varying switch-over time intervals. The magnitude of voltage is bounded while the switch-over time intervals are constantly adjusted to achieve an optimum control. Numerical examples presented in the paper demonstrate the effectiveness of the method and the possibility of reducing the vibrations to very small amplitudes within a short time interval which is in the order of a second.

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Understanding Molecular Clocks and Time Trees

10.7591/cornell/9781501752773.003.0011 ◽

2021 ◽

pp. 326-337

Author(s):

Andrew V. Z. Brower ◽

Randall T. Schuh

Keyword(s):

Amino Acid ◽

Molecular Clock ◽

Significant Error ◽

Evolutionary Tree ◽

Molecular Clocks ◽

Amino Acid Substitutions ◽

Absolute Minimum ◽

Short Time ◽

Over Time ◽

Age Estimates

This chapter examines molecular clocks and time trees. Although laden with numerous process assumptions that may or may not be true (or knowable), the idea is appealingly straightforward: if amino acid substitutions in proteins occurred at a relatively steady pace that were more or less constant both over time and along each of the branches of a diverging evolutionary tree, then the number of substitutions would be directly related to the time since the taxa in question diverged from one another. However, evidence does not support a universal molecular clock. Evidence might or might not support “local” clocklike evolution among closely related taxa over relatively short time spans. Although absolute minimum ages for clades may be inferred from fossils, from biogeographical patterns, or extrapolated from secondary calibrations, such age estimates are subject to potentially significant error due to vagaries of geological dating as well as ambiguities of fossil identity. The test of a time tree hypothesis is to discover new fossil evidence that corroborates or falsifies it.

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