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1. The second data release from the European Pulsar Timing Array IV. Search for continuous gravitational wave signals

Author

Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferranti, I., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Manzini, S., Mickaliger, M. B., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, Joris, Wang, J., Wang, L., Wu, Z., AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Laboratoire Univers et Théories (LUTH (UMR_8102))

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics of Galaxies (astro-ph.GA), [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the results of a search for continuous gravitational wave signals (CGWs) in the second data release (DR2) of the European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this search has a gravitational wave frequency of 4-5 nHz. Such a signal could be generated by a supermassive black hole binary (SMBHB) in the local Universe. We present the results of a follow-up analysis of this candidate using both Bayesian and frequentist methods. The Bayesian analysis gives a Bayes factor of 4 in favor of the presence of the CGW over a common uncorrelated noise process, while the frequentist analysis estimates the p-value of the candidate to be 1%, also assuming the presence of common uncorrelated red noise. However, comparing a model that includes both a CGW and a gravitational wave background (GWB) to a GWB only, the Bayes factor in favour of the CGW model is only 0.7. Therefore, we cannot conclusively determine the origin of the observed feature, but we cannot rule it out as a CGW source. We present results of simulations that demonstrate that data containing a weak gravitational wave background can be misinterpreted as data including a CGW and vice versa, providing two plausible explanations of the EPTA DR2 data. Further investigations combining data from all PTA collaborations will be needed to reveal the true origin of this feature., 12 figures, 15 pages, to be submitted

Published
2023

2. The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals

Author

Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. -S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. -M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Mickaliger, M. B., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, Joris, Wang, J., Wang, L., Wu, Z., AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Laboratoire Univers et Théories (LUTH (UMR_8102))

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the results of the search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using the second data release of the European Pulsar Timing Array (EPTA) for 25 millisecond pulsars and a combination with the first data release of the Indian Pulsar Timing Array (InPTA). We analysed (i) the full 24.7-year EPTA data set, (ii) its 10.3-year subset based on modern observing systems, (iii) the combination of the full data set with the first data release of the InPTA for ten commonly timed millisecond pulsars, and (iv) the combination of the 10.3-year subset with the InPTA data. These combinations allowed us to probe the contributions of instrumental noise and interstellar propagation effects. With the full data set, we find marginal evidence for a GWB, with a Bayes factor of four and a false alarm probability of $4\%$. With the 10.3-year subset, we report evidence for a GWB, with a Bayes factor of $60$ and a false alarm probability of about $0.1\%$ ($\gtrsim 3\sigma$ significance). The addition of the InPTA data yields results that are broadly consistent with the EPTA-only data sets, with the benefit of better noise modelling. Analyses were performed with different data processing pipelines to test the consistency of the results from independent software packages. The inferred spectrum from the latest EPTA data from new generation observing systems is rather uncertain and in mild tension with the common signal measured in the full data set. However, if the spectral index is fixed at 13/3, the two data sets give a similar amplitude of ($2.5\pm0.7)\times10^{-15}$ at a reference frequency of $1\,{\rm yr}^{-1}$. By continuing our detection efforts as part of the International Pulsar Timing Array (IPTA), we expect to be able to improve the measurement of spatial correlations and better characterise this signal in the coming years., Comment: 21 pages, 14 figures, 4 appendix figures, accepted for publication in A&A

Published
2023
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7. Assessment of Eating Behavior During the COVID-19 Pandemic Period. A Pilot Study

Author

Nitu Ionel, Rus Victoria Ancuta, Sipos Remus Sebastian, Nyulas Tiberiu, Cherhat Maria Paula, Ruta Florina, and Tita Constanta Corina Nitu

Subjects
covid-19, isolation, lifestyle, nutrition, diet, Medicine
Abstract

Background: In order to counter and control the spread of the new COVID-19 pandemic, at the beginning of March 2020, the Romanian government decided to apply strict isolation and quarantine measures. Objective: In the present study, we aimed to analyze the impact of the COVID-19 pandemic and isolation/quarantine at home on lifestyle and daily diet, and to identify changes caused by the pandemic related to the nutritional status and food preferences of the Romanian population. Material and Method: We conducted a prospective observational study based on a structured questionnaire that included 30 items for investigating multiple aspects regarding the dietary habits in the context of the pandemic, quarantine and social isolation imposed by the new SARS-CoV-2 coronavirus. The questionnaire was disseminated on various online platforms accessible from any device with an internet connection in Romania, on social media groups between January and March 2021. The questionnaire was made online, using the Google Forms platform, this method being very useful for carrying out the proposed evaluation, as it facilitated the national dissemination of the evaluation questionnaire. The final study group consisted of 620 respondents from 35 counties of Romania. Results: Regarding weight status, we found that the respondents showed significantly more frequent weight fluctuations during the pandemic than before (p

Published
2021
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9. Relative Contribution of Metabolic Syndrome Components in Relation to Obesity and Insulin Resistance in Postmenopausal Osteoporosis.

Author

Greere D, Grigorescu F, Manda D, Voicu G, Lautier C, Nitu I, and Poiana C

Abstract

Introduction . Osteoporosis (OP) affects 30% of postmenopausal women, often complicated by metabolic syndrome (MetS) with a still controversial role. We aimed to characterize MetS and its components in relation to bone mineral density (BMD), body mass index (BMI), and insulin resistance. Methods . Patients ( n = 188) underwent DEXA scans, spine X-rays, and metabolic and hormonal investigations, including bone biomarkers, muscular strength, and physical performance tests, while insulin resistance was evaluated by the Homeostasis Model Assessment (HOMA-IR). Results . Patients with a normal BMD or osteopenia ( n = 68) and with OP ( n = 120) displayed 51.5% and 30.8% of MetS, but without differences in insulin resistance. When BMD was studied as a function of the cumulative MetS criteria and centiles of BMI, lower levels of BMD were observed beyond an inflection point of 27.2 kg/m 2 for BMI, allowing for further stratification as lean and overweight/obese (OW/OB) subjects. In contrast with lean individuals ( n = 74), in OW/OB patients ( n = 46), MetS was associated with HbA1c ( p < 0.0037, OR 9.6, 95% CI [1.64-55.6]) and insulin resistance ( p < 0.0076, OR 6.7, 95% CI [1.49-30.8]) in the context where BMD values were lower than those predicted from BMI in non-OP subjects. In OP patients with fragility fractures (31% of MetS), glycemia also appeared to be the dominant factor for MetS ( p < 0.0005, OR 4.1, 95% CI [1.63-10.39]). Conclusions . These data indicate a detrimental effect of insulin resistance in MetS on OP patients, while the prevalence of the syndrome depends on the proportion of obesity. These findings provide new insights into the pathogenic role of MetS and reveal the need to consider different strata of BMI and insulin resistance when studying postmenopausal OP.

Published
2024
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10. Biologic response to desmopressin in patients with severe type 1 and type 2 von Willebrand disease: results of a multicenter European study.

Author

Federici AB, Mazurier C, Berntorp E, Lee CA, Scharrer I, Goudemand J, Lethagen S, Nitu I, Ludwig G, Hilbert L, and Mannucci PM

Subjects
Adolescent, Adult, Aged, Child, Europe, Genotype, Humans, Middle Aged, Phenotype, Point Mutation, Prospective Studies, Severity of Illness Index, Treatment Outcome, von Willebrand Diseases genetics, Deamino Arginine Vasopressin administration & dosage, Hemostatics administration & dosage, von Willebrand Diseases drug therapy
Abstract

This study prospectively evaluated the rate of biologic response to desmopressin (DDAVP) in 66 patients with type 1 or 2 von Willebrand disease (VWD), each of whom had, on the basis of available records, a clinically significant bleeding history and at least one of the following laboratory abnormalities: bleeding time (BT) longer than 15 minutes, ristocetin cofactor activity (VWF:RCo) less than 10 IU/dL, factor VIII coagulant activity (FVIII:C) less than 20 IU/dL (severe VWD). Before the study, responsive patients were defined as those who, 2 hours after infusion of 0.3 microg/kg DDAVP, had increased baseline values of VWF:RCo and FVIII:C by at least 3-fold and achieved levels of at least 30 IU/dL for both and a BT of 12 minutes or less. The rate of biologic response varied according to VWD types and was higher in type 1 (7 of 26, 27%) than in type 2 (7 of 40, 18%) (type 2A [1 of 15, 7%], type 2M [3 of 21, 14%], type 2N [3 of 4, 75%]). Mutations in the VWF gene were previously known or newly identified in most patients with types 2A (n = 15 of 15), 2M (n = 15 of 21), and 2N (n = 4 of 4), but in none of those with type 1 VWD. Genotype provided more information than phenotype in predicting individual responses to DDAVP only in patients with 2A and 2N VWD. This prospective study showed that the rate of biologic response to DDAVP is relatively low not only in type 2 but also in type 1 VWD when uniform and stringent criteria for patient selection and responsiveness are applied.

Published
2004
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