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  • 1
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    FRIPON: a worldwide network to track incoming meteoroids
    EDP Sciences ; 2020
    In:  Astronomy & Astrophysics Vol. 644 ( 2020-12), p. A53-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 644 ( 2020-12), p. A53-
    Abstract: Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile – hence precious – meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 10 6 km 2 . Methods. The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results. Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag 〈 –5; meteoroid size ≥~1 cm) amounts to 1250/yr/10 6 km 2 . This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202038649
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 2
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    Cavezzo, the first Italian meteorite recovered by the PRISMA fireball network. Orbit, trajectory, and strewn-field
    Oxford University Press (OUP) ; 2020
    In:  Monthly Notices of the Royal Astronomical Society Vol. 501, No. 1 ( 2020-12-30), p. 1215-1227
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 501, No. 1 ( 2020-12-30), p. 1215-1227
    Abstract: Two meteorite pieces have been recovered in Italy, near the town of Cavezzo (Modena), on 2020 January 4th. The associated fireball was observed on the evening of New Year’s Day 2020 by eight all-sky cameras of the PRISMA fireball network, a partner of FRIPON. The computed trajectory had an inclination angle of approximately 68° and a velocity at infinity of 12.8 km s−1. Together with the relatively low terminal height, estimated as 21.5 km, those values were indicating the significant possibility of a meteorite dropping event, as additionally confirmed by the non-zero residual total mass. The strewn-field was computed taking into account the presence of two bright light flashes, revealing that the meteoroid had been very likely subject to fragmentation. Three days after the event, two samples, weighing 3.1 and 52.2 g, were collected as a result of a dedicated field search and thanks to the involvement of the local people. The two pieces were immediately recognized as freshly fallen fragments of meteorite. The computed orbital elements, compared with the ones of known Near-Earth Asteroids from the NEODyS database, are compatible with one asteroid only; 2013 VC10. The estimated original mass of the meteoroid, 3.5 kg, and size, approximately 13 cm, is so far the smallest among the current 35 cases in which meteorites were recovered from precise strewn-field computation thanks to observational data. This result demonstrates the effectiveness of accurate processing of fireball network data even on challenging events generated by small size meteoroids.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1093/mnras/staa3646
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2020
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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  • 3
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    Luminous efficiency of meteors derived from ablation model after assessment of its range of validity
    EDP Sciences ; 2021
    In:  Astronomy & Astrophysics Vol. 652 ( 2021-8), p. A84-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 652 ( 2021-8), p. A84-
    Abstract: Context. The luminous efficiency, τ , can be used to compute the pre-atmospheric masses of meteoroids from corresponding recorded meteor brightnesses. The derivation of the luminous efficiency is non-trivial and is subject to biases and model assumptions. This has led to greatly varying results in the last decades of studies. Aims. The present paper aims to investigate how a reduction in various observational biases can be achieved to derive (more) reliable values for the luminous efficiency. Methods. A total of 281 meteors observed by the Fireball Recovery and InterPlanetary Observation Network (FRIPON) are studied. The luminous efficiencies of the events are computed using an ablation-based model. The relations of τ as a function of the pre-atmospheric meteoroid velocity, v e , and mass, M e , are studied. Various aspects that could render the method less valid, cause inaccuracies, or bias the results are investigated. On this basis, the best suitable meteors were selected for luminous efficiency computations. Results. The presented analysis shows the limits of the used method. The most influential characteristics that are necessary for reliable results for the τ computation were identified. We study the dependence of τ on the assumed meteoroid’s density, ρ , and include improved ρ -values for objects with identified meteoroid stream association. Based on the discovered individual biases and constraints we create a pre-debiased subset of 54 well-recorded events with a relative velocity change 〉 80%, a final height 〈 70 km, and a Knudsen number Kn 〈 0.01; this last value indicates that the events were observed in the continuum-flow regime. We find τ -values in the range between 0.012% and 1.1% for this pre-debiased subset and relations of τ to v e and M e of: τ =7.33⋅ v e −1.10 and τ =0.28⋅ M e −0.33 . Conclusions. The derived luminous efficiency of meteoroids depends on the assumed material density. Our results indicate that the applied debiasing method improves the analysis of τ from decelerated meteoroids. The underlying method is only valid for meteors in the continuum-flow regime. These events tend to have low end heights, large masses, and high deceleration.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202140917
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 4
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    Luminous efficiency based on FRIPON meteors and limitations of ablation models
    EDP Sciences ; 2021
    In:  Astronomy & Astrophysics Vol. 650 ( 2021-6), p. A159-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 650 ( 2021-6), p. A159-
    Abstract: Context. In meteor physics, the luminous efficiency τ is used to convert the meteor’s magnitude to the corresponding meteoroid’s mass. However, a lack of sufficiently accurate verification methods or adequate laboratory tests mean that discussions around this parameter are a subject of controversy. Aims. In this work, we aim to use meteor data obtained by the Fireball Recovery and InterPlanetary Observation to calculate the luminous efficiencies of the recorded meteors. We also show the limitations of the methods presented herein. Methods. Deceleration-based formulas were used to calculate the masses of the pre-atmospheric meteoroids. These can in turn be compared to the meteor brightnesses to assess the luminous efficiencies of the recorded objects. Fragmentation of the meteoroids is not considered within this model. Good measurements of the meteor deceleration are required. Results. We find τ -values, as well as the shape change coefficients, of 294 meteors and fireballs with determined masses in the range of 10 −6 –100 kg. The derived τ -values have a median of τ median = 2.17%. Most of them are of the order of 0.1–10%. We present how our values are obtained, compare them with data reported in the literature, and discuss several methods. A dependence of τ on the pre-atmospheric velocity of the meteor, v e , is noticeable with a relation of τ = 0.0023⋅ v e 2.3 . Furthermore, a dependence of τ on the initial meteoroid mass, M e , is found with negative linear behaviour in log–log space: τ = 0.48⋅ M e −0.47 . Conclusions. The higher luminous efficiency of fast meteors could be explained by the higher amount of energy released. Fast meteoroids produce additional emission lines that radiate more efficiently in specific wavelengths due to the appearance of the so-called second component of higher temperature. Furthermore, the negative dependence of τ on M e implies that the radiation of smaller meteoroids is more efficient. The results of this study also show the limitations of the ablation-based model for the determination of the luminous efficiency.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202040204
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 5
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    Hypoxic stimulus alters hypothalamic AMP-activated protein kinase phosphorylation concomitant to hypophagia
    American Physiological Society ; 2007
    In:  Journal of Applied Physiology Vol. 102, No. 6 ( 2007-06), p. 2135-2141
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 102, No. 6 ( 2007-06), p. 2135-2141
    Abstract: Acute exposure to hypobaric hypoxia is known to decrease food intake, but the molecular mechanisms of such alteration in feeding behavior remain unknown. We tested the hypothesis that hypothalamic AMP-activated protein kinase (AMPK) phosphorylation is affected by acute exposure to hypobaric hypoxia and thus would be involved in initial anorexia. To address this issue, male rats weighing 255–270 g were either submitted to hypobaric hypoxia (H, equivalent altitude of 5,500 m), maintained under local barometric pressure conditions (N), or pair-fed an equivalent quantity of food to that consumed by H rats (PF), for 6, 24, or 48 h. Daily food intake dropped by 73% during the first day of hypoxia ( P 〈 0.01) and remained by 46% lower than in N rats thereafter ( P 〈 0.01). Hypoxia per se, as estimated by comparing experimental data between the H and PF groups, increased ob gene transcription and plasma leptin concentration. A transient increase in glucose availability occurred in the H group compared with PF animals ( P 〈 0.05). The hypoxic stimulus led to an early and transient decrease in hypothalamic AMPK and acetyl-CoA carboxylase (ACC) phosphorylation, concomitant with hypophagia and associated alterations in nutrients and hormones. An increase in NPY mRNA levels occurred from day 1, similarly in H and PF rats, and thus mainly related to food restriction alone ( P 〈 0.05). In conclusion, the present study demonstrates that hypoxia per se inhibited AMPK and ACC phosphorylation in the hypothalamus, concomitant with profound anorexia. A powerful counterregulation occurs rapidly, mediated by NPY and devoted to avoid prolonged anorexia.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.01150.2006
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2007
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 6
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    Energy signature of ton TNT-class impacts: analysis of the 2018 December 22 fireball over Western Pyrenees
    Oxford University Press (OUP) ; 2021
    In:  Monthly Notices of the Royal Astronomical Society Vol. 508, No. 4 ( 2021-10-30), p. 5716-5733
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 508, No. 4 ( 2021-10-30), p. 5716-5733
    Abstract: The increase in detector sensitivity and availability in the past three decades has allowed us to derive knowledge of the meteoroid flux and impact energy into the Earth’s atmosphere. We present the multi-instrument detected 2018 December 22 fireball over Western Pyrenees, and compare several techniques aiming to obtain a reliable method to be used when measuring impacts of similar scale. From trajectory data alone, we found a bulk density of 3.5 g cm−3 to be the most likely value for the Pyrenean meteoroid. This allowed to further constrain the dynamic mass, which translated into a kinetic energy of 1 ton TNT (4.184 × 109 J). For the second energy derivation, via the fireball’s corrected optical radiation, we obtained a more accurate empirical relation measuring well-studied bolides. The result approximates to 1.1 ton TNT, which is notably close to the nominal dynamic result, and agrees with the lower margin of the seismic-based energy estimation, yet way lower than the infrasound estimate. Based on the relation derived in this study, we consider the nominal estimate from both the dynamic and photometric methods to be the most accurate value of deposited energy (1 ton TNT). We show that the combination of these two methods can be used to infer the meteoroid density. Among the methods presented in this paper, we found that the optical energy is the most reliable predictor of impact energy near the ton TNT-scale.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1093/mnras/stab2968
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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  • 7
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    Variabilité des compositions cellulaire et moléculaire des extraits de concentrés plaquettaires (platelet-rich plasma, PRP)
    Elsevier BV ; 2012
    In:  Journal de Traumatologie du Sport Vol. 29, No. 4 ( 2012-12), p. 236-240
    Details
    In: Journal de Traumatologie du Sport, Elsevier BV, Vol. 29, No. 4 ( 2012-12), p. 236-240
    Type of Medium: Online Resource
    ISSN: 0762-915X
    URL: Article
    DOI: 10.1016/j.jts.2012.10.002
    Language: French
    Publisher: Elsevier BV
    Publication Date: 2012
    SSG: 31
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  • 8
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    Effect of hypoxia exposure on the phenotypic adaptation in remodelling skeletal muscle submitted to functional overload
    Wiley ; 2013
    In:  Acta Physiologica Vol. 209, No. 4 ( 2013-12), p. 272-282
    Details
    In: Acta Physiologica, Wiley, Vol. 209, No. 4 ( 2013-12), p. 272-282
    Abstract: To determine whether hypoxia influences the phenotypic adaptation of skeletal muscle induced by mechanical overload. Methods Plantaris muscles of female rats were submitted to mechanical overload following synergist ablation. After 3 days of overload, rats were exposed to either hypobaric hypoxia (equivalent to 5500 m) or normoxia. Muscles were collected after 5, 12 and 56 days of overload (i.e. after 3, 9 and 53 days of hypoxia). We determined the myosin heavy chain (MHC) distribution, mRNA levels of myocyte‐enriched calcineurin‐integrating protein 1 (MCIP1) to indirectly assess calcineurin activity, the changes in oxidative capacity from the activities of citrate synthase (CS) and cytochrome c oxidase (COX), and the expression of regulators involved in mitochondrial biogenesis (Pgc‐1α, NRF1 and Tfam) and degradation (BNIP‐3). Results Hypoxia did not alter the fast‐to‐slow MHC shift and the increase in calcineurin activity induced by overload; it only transiently slowed down the overload‐induced transition in MHC isoforms. Hypoxia similarly decreased CS and COX activities in overloaded and control muscles. Nuclear respiratory factor 1 (NRF1) and transcription factor A (Tfam) mRNA and BNIP‐3 protein were not influenced by hypoxia in overloaded muscles, whereas Pgc‐1α mRNA and protein contents did not correlate with changes in oxidative capacity. Conclusion Hypoxia is not a critical stimulus to modulate the fast‐to‐slow MHC transition associated with overload. Thus, the impairment of the fast‐to‐slow fibre shift often observed during post‐natal development in hypoxia could be explained by the lower voluntary locomotor activity associated with hypoxia. Hypoxia alters mitochondrial oxidative capacity, but this adaptive response is similar in overloaded and control muscles.
    Type of Medium: Online Resource
    ISSN: 1748-1708 , 1748-1716
    URL: Issue
    URL: Article
    DOI: 10.1111/apha.2013.209.issue-4
    DOI: 10.1111/apha.12110
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2617148-X
    detail.hit.zdb_id: 2219379-0
    SSG: 12
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  • 9
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    Pitfalls in target mRNA quantification for real-time quantitative RT-PCR in overload-induced skeletal muscle hypertrophy
    American Physiological Society ; 2011
    In:  Physiological Genomics Vol. 43, No. 4 ( 2011-02), p. 228-235
    Details
    In: Physiological Genomics, American Physiological Society, Vol. 43, No. 4 ( 2011-02), p. 228-235
    Abstract: Quantifying target mRNA using real-time quantitative reverse transcription-polymerase chain reaction requires an accurate normalization method. Determination of normalization factors (NFs) based on validated reference genes according to their relative stability is currently the best standard method in most usual situations. This method controls for technical errors, but its physiological relevance requires constant NF values for a fixed weight of tissue. In the functional overload model, the increase in the total RNA concentration must be considered in determining the NF values. Here, we pointed out a limitation of the classical geNorm-derived normalization. geNorm software selected reference genes despite that the NF values extensively varied under experiment. Only the NF values calculated from four intentionally selected genes were constant between groups. However, a normalization based on these genes is questionable. Indeed, three out of four genes belong to the same functional class (negative regulator of muscle mass), and their use is physiological nonsense in a hypertrophic model. Thus, we proposed guidelines for optimizing target mRNA normalization and quantification, useful in models of muscle mass modulation. In our study, the normalization method by multiple reference genes was not appropriate to compare target mRNA levels between overloaded and control muscles. A solution should be to use an absolute quantification of target mRNAs per unit weight of tissue, without any internal normalization. Even if the technical variations will stay present as a part of the intergroup variations, leading to less statistical power, we consider this method acceptable because it will not generate misleading results.
    Type of Medium: Online Resource
    ISSN: 1094-8341 , 1531-2267
    URL: Article
    DOI: 10.1152/physiolgenomics.00109.2010
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2011
    detail.hit.zdb_id: 2031330-5
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  • 10
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    Quantification of low-expressed mRNA using 5′ LNA-containing real-time PCR primers
    Elsevier BV ; 2007
    In:  Biochemical and Biophysical Research Communications Vol. 354, No. 1 ( 2007-03), p. 246-252
    Details
    In: Biochemical and Biophysical Research Communications, Elsevier BV, Vol. 354, No. 1 ( 2007-03), p. 246-252
    Type of Medium: Online Resource
    ISSN: 0006-291X
    URL: Article
    DOI: 10.1016/j.bbrc.2006.12.194
    RVK:
    WA 15000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2007
    detail.hit.zdb_id: 1461396-7
    SSG: 12
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