LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 35

Search options

  1. Article: A Brief Theory of Epidemic Kinetics.

    Louchet, François

    Biology

    2020  Volume 9, Issue 6

    Abstract: In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops ... ...

    Abstract In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops through contacts between contagious and exposed people, with a rate proportional to the number of contagious and of non-immune individuals, to contact duration and turnover, inversely proportional to the efficiency of protection measures, and balanced by the average individual recovery response. The obvious initial exponential increase is readily hindered by the growing recovery rate, and also by the size reduction of the exposed population. The system converges towards a stable attractor whose value is expressed in terms of the "reproductive rate"
    Keywords covid19
    Language English
    Publishing date 2020-06-22
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2661517-4
    ISSN 2079-7737
    ISSN 2079-7737
    DOI 10.3390/biology9060134
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  2. Article ; Online: A Brief Theory of Epidemic Kinetics

    François Louchet

    Biology, Vol 9, Iss 134, p

    2020  Volume 134

    Abstract: In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops ... ...

    Abstract In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops through contacts between contagious and exposed people, with a rate proportional to the number of contagious and of non-immune individuals, to contact duration and turnover, inversely proportional to the efficiency of protection measures, and balanced by the average individual recovery response. The obvious initial exponential increase is readily hindered by the growing recovery rate, and also by the size reduction of the exposed population. The system converges towards a stable attractor whose value is expressed in terms of the “reproductive rate” R 0 , depending on contamination and recovery factors. Various properties of the attractor are examined, and particularly its relations with R 0 . Decreasing this ratio below a critical value leads to a tipping threshold beyond which the epidemic is over. By contrast, significant values of the above ratio may bring the system through a bifurcating hierarchy of stable cycles up to a chaotic behaviour.
    Keywords epidemic ; COVID-19 ; contamination kinetics ; herd immunity ; dynamical systems ; reproductive rate ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  3. Book ; Online: A Brief Theory of Epidemic Kinetics

    François Louchet

    Biology ; Volume 9 ; Issue 6

    2020  

    Abstract: In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops ... ...

    Abstract In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops through contacts between contagious and exposed people, with a rate proportional to the number of contagious and of non-immune individuals, to contact duration and turnover, inversely proportional to the efficiency of protection measures, and balanced by the average individual recovery response. The obvious initial exponential increase is readily hindered by the growing recovery rate, and also by the size reduction of the exposed population. The system converges towards a stable attractor whose value is expressed in terms of the “

    reproductive rate”

    R0, depending on contamination and recovery factors. Various properties of the attractor are examined, and particularly its relations with R0. Decreasing this ratio below a critical value leads to a tipping threshold beyond which the epidemic is over. By contrast, significant values of the above ratio may bring the system through a bifurcating hierarchy of stable cycles up to a chaotic behaviour.
    Keywords epidemic ; COVID-19 ; contamination kinetics ; herd immunity ; dynamical systems ; reproductive rate ; critical state ; attractor ; stable cycle ; chaos ; covid19
    Subject code 612
    Language English
    Publishing date 2020-06-22
    Publisher Multidisciplinary Digital Publishing Institute
    Publishing country ch
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  4. Article: A Brief Theory of Epidemic Kinetics

    Louchet, François

    Biology. 2020 June 22, v. 9, no. 6

    2020  

    Abstract: In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops ... ...

    Abstract In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops through contacts between contagious and exposed people, with a rate proportional to the number of contagious and of non-immune individuals, to contact duration and turnover, inversely proportional to the efficiency of protection measures, and balanced by the average individual recovery response. The obvious initial exponential increase is readily hindered by the growing recovery rate, and also by the size reduction of the exposed population. The system converges towards a stable attractor whose value is expressed in terms of the “reproductive rate” R₀, depending on contamination and recovery factors. Various properties of the attractor are examined, and particularly its relations with R₀. Decreasing this ratio below a critical value leads to a tipping threshold beyond which the epidemic is over. By contrast, significant values of the above ratio may bring the system through a bifurcating hierarchy of stable cycles up to a chaotic behaviour.
    Keywords COVID-19 infection ; at-risk population ; epidemiology ; people
    Language English
    Dates of publication 2020-0622
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2661517-4
    ISSN 2079-7737
    ISSN 2079-7737
    DOI 10.3390/biology9060134
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  5. Article: A brief theory of epidemic kinetics

    Louchet, François

    Biology

    Abstract: In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops ... ...

    Abstract In the context of the COVID-19 epidemic, and on the basis of the Theory of Dynamical Systems, we propose a simple theoretical approach for the expansion of contagious diseases, with a particular focus on viral respiratory tracts. The infection develops through contacts between contagious and exposed people, with a rate proportional to the number of contagious and of non-immune individuals, to contact duration and turnover, inversely proportional to the efficiency of protection measures, and balanced by the average individual recovery response. The obvious initial exponential increase is readily hindered by the growing recovery rate, and also by the size reduction of the exposed population. The system converges towards a stable attractor whose value is expressed in terms of the “reproductive rate” R0, depending on contamination and recovery factors. Various properties of the attractor are examined, and particularly its relations with R0. Decreasing this ratio below a critical value leads to a tipping threshold beyond which the epidemic is over. By contrast, significant values of the above ratio may bring the system through a bifurcating hierarchy of stable cycles up to a chaotic behaviour.
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #614828
    Database COVID19

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  6. Article ; Online: Trends in harmful drug exposure during pregnancy in France between 2013 and 2019: A nationwide cohort study.

    Louchet, Margaux / Collier, Mathis / Beeker, Nathanaël / Mandelbrot, Laurent / Sibiude, Jeanne / Chouchana, Laurent / Treluyer, Jean Marc

    PloS one

    2024  Volume 19, Issue 1, Page(s) e0295897

    Abstract: ... in France.: Design: Nationwide cohort study.: Setting: The French National administrative health ...

    Abstract Objective: Describe the trends of exposure to harmful drugs during pregnancy over recent years in France.
    Design: Nationwide cohort study.
    Setting: The French National administrative health Data System (SNDS).
    Population: Pregnancies starting between 2013 and 2019 and outcomes corresponding to live births, medical terminations of pregnancy, and stillbirths.
    Methods: Each pregnancy was divided into a preconceptional period of 90 days before conception and three trimesters from conception to birth. Harmful drugs were defined according to their risks to the fetus: teratogenicity or fetotoxicity. Exposure was defined using the critical period during pregnancy for each type of harmful drug: preconceptional period or first trimester for teratogenic drugs and second or third trimesters for fetotoxic drugs.
    Main outcome measures: Prevalence of pregnancies exposed to at least one harmful drug.
    Results: Among 5,253,284 pregnancies, 204,402 (389 per 10,000) pregnancies were exposed to at least one harmful drug during the critical periods: 48,326 (92 per 10,000) pregnancies were exposed to teratogenic drugs during the preconceptional period or the first trimester, and 155,514 (299 per 10,000) pregnancies were exposed to fetotoxic drugs during the second or third trimesters. Teratogenic drugs were mainly retinoids for topical use (44 per 10,000 pregnancies), antiepileptics (13 per 10,000 pregnancies) and statins (13 per 10,000 pregnancies). Fetotoxic drugs were mainly non-steroidal anti-inflammatory drugs (NSAIDs), for systemic (128 per 10,000 pregnancies) and topical use (122 per 10,000 pregnancies). Exposure to teratogenic drugs decreased from the preconceptional period to the first trimester. Exposure to fetotoxic drugs decreased from the second to the third trimester. Between 2013 and 2019, we found a decrease in harmful drug exposure overall, mainly for topical and systemic NSAIDs and for topical retinoids.
    Conclusions: In this nationwide study, about one in 25 pregnancies was exposed to at least one harmful drug, mainly NSAIDs and topical retinoids. Although the prevalence of harmful drug exposure decreased over the study period, NSAID exposure in the second and third trimester remains of concern.
    MeSH term(s) Female ; Pregnancy ; Humans ; Cohort Studies ; France/epidemiology ; Anti-Inflammatory Agents, Non-Steroidal/adverse effects ; Anticonvulsants ; Retinoids ; Teratogens
    Chemical Substances Anti-Inflammatory Agents, Non-Steroidal ; Anticonvulsants ; Retinoids ; Teratogens
    Language English
    Publishing date 2024-01-10
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2267670-3
    ISSN 1932-6203 ; 1932-6203
    ISSN (online) 1932-6203
    ISSN 1932-6203
    DOI 10.1371/journal.pone.0295897
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  7. Article ; Online: Trends in harmful drug exposure during pregnancy in France between 2013 and 2019

    Margaux Louchet / Mathis Collier / Nathanaël Beeker / Laurent Mandelbrot / Jeanne Sibiude / Laurent Chouchana / Jean Marc Treluyer

    PLoS ONE, Vol 19, Iss 1, p e

    A nationwide cohort study.

    2024  Volume 0295897

    Abstract: ... in France. Design Nationwide cohort study. Setting The French National administrative health Data System ...

    Abstract Objective Describe the trends of exposure to harmful drugs during pregnancy over recent years in France. Design Nationwide cohort study. Setting The French National administrative health Data System (SNDS). Population Pregnancies starting between 2013 and 2019 and outcomes corresponding to live births, medical terminations of pregnancy, and stillbirths. Methods Each pregnancy was divided into a preconceptional period of 90 days before conception and three trimesters from conception to birth. Harmful drugs were defined according to their risks to the fetus: teratogenicity or fetotoxicity. Exposure was defined using the critical period during pregnancy for each type of harmful drug: preconceptional period or first trimester for teratogenic drugs and second or third trimesters for fetotoxic drugs. Main outcome measures Prevalence of pregnancies exposed to at least one harmful drug. Results Among 5,253,284 pregnancies, 204,402 (389 per 10,000) pregnancies were exposed to at least one harmful drug during the critical periods: 48,326 (92 per 10,000) pregnancies were exposed to teratogenic drugs during the preconceptional period or the first trimester, and 155,514 (299 per 10,000) pregnancies were exposed to fetotoxic drugs during the second or third trimesters. Teratogenic drugs were mainly retinoids for topical use (44 per 10,000 pregnancies), antiepileptics (13 per 10,000 pregnancies) and statins (13 per 10,000 pregnancies). Fetotoxic drugs were mainly non-steroidal anti-inflammatory drugs (NSAIDs), for systemic (128 per 10,000 pregnancies) and topical use (122 per 10,000 pregnancies). Exposure to teratogenic drugs decreased from the preconceptional period to the first trimester. Exposure to fetotoxic drugs decreased from the second to the third trimester. Between 2013 and 2019, we found a decrease in harmful drug exposure overall, mainly for topical and systemic NSAIDs and for topical retinoids. Conclusions In this nationwide study, about one in 25 pregnancies was exposed to at least one harmful drug, mainly NSAIDs ...
    Keywords Medicine ; R ; Science ; Q
    Subject code 610
    Language English
    Publishing date 2024-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  8. Article ; Online: Delayed-interval delivery of twins in 13 pregnancies.

    Louchet, Margaux / Dussaux, Chloé / Luton, Dominique / Goffinet, François / Bounan, Stéphane / Mandelbrot, Laurent

    Journal of gynecology obstetrics and human reproduction

    2019  Volume 49, Issue 2, Page(s) 101660

    Abstract: Background: Delayed interval delivery is a rare practice aiming at prolonging gestation for the second twin in case of pre-viable birth of twin one. Our objective was to identify factors related to successful delayed delivery of the second twin, among ... ...

    Abstract Background: Delayed interval delivery is a rare practice aiming at prolonging gestation for the second twin in case of pre-viable birth of twin one. Our objective was to identify factors related to successful delayed delivery of the second twin, among cases in which the interval after delivery of the first twin was above 24h.
    Method: A descriptive, retrospective and multicenter study of all delayed interval deliveries in dichorionic twins in 4 perinatal centers in Paris over a 14-year period.
    Results: In 13 cases of delayed interval delivery, delivery of twin 1 was at a median of 18 weeks' gestation (range 14WG+2days to 24WG), and none survived. Delivery of the second twin occurred at a median of 25 weeks' gestation +3 days, 51 days after twin 1 (range 13-138 days). Seven of the 13s twins (54 %) survived. There were 5 cases of chorioamnionitis and 1 case of maternal disseminated intravascular coagulation. Poor outcome was not significantly associated with the gestational age, presentation for PPROM or inflammatory markers (C-reactive protein and white blood cell count) at the time of delivery of twin 1.
    Conclusion: Delayed-interval delivery of the second twin may prolong pregnancy and lead the second twin child to a viable term of birth; but carries a risk of maternal complications.
    MeSH term(s) Adult ; Delivery, Obstetric/methods ; Female ; Gestational Age ; Humans ; Infant, Newborn ; Pregnancy ; Pregnancy, Twin ; Retrospective Studies ; Time Factors
    Language English
    Publishing date 2019-12-03
    Publishing country France
    Document type Journal Article ; Multicenter Study
    ISSN 2468-7847
    ISSN (online) 2468-7847
    DOI 10.1016/j.jogoh.2019.101660
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  9. Article ; Online: Ultrasound-modulated optical tomography in scattering media: flux filtering based on persistent spectral hole burning in the optical diagnosis window.

    Venet, Caroline / Bocoum, Maïmouna / Laudereau, Jean-Baptiste / Chaneliere, Thierry / Ramaz, François / Louchet-Chauvet, Anne

    Optics letters

    2018  Volume 43, Issue 16, Page(s) 3993–3996

    Abstract: Ultrasound-modulated optical tomography (UOT) is a powerful imaging technique to discriminate healthy from unhealthy biological tissues based on their optical signature. Among the numerous detection techniques developed for acousto-optic imaging, only ... ...

    Abstract Ultrasound-modulated optical tomography (UOT) is a powerful imaging technique to discriminate healthy from unhealthy biological tissues based on their optical signature. Among the numerous detection techniques developed for acousto-optic imaging, only those based on spectral filtering are intrinsically immune to speckle decorrelation. This Letter reports on UOT imaging based on spectral hole burning in Tm:YAG crystal under a moderate magnetic field (200G) with a well-defined orientation. The deep and long-lasting holes translate into a more efficient UOT imaging with a higher contrast and faster imaging frame rate. We demonstrate the potential of this method by imaging calibrated phantom scattering gels.
    Language English
    Publishing date 2018-08-14
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4794
    ISSN (online) 1539-4794
    DOI 10.1364/OL.43.003993
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  10. Article ; Online: Structured ultrasound-modulated optical tomography.

    Bocoum, Maïmouna / Gennisson, Jean-Luc / Laudereau, Jean-Baptiste / Louchet-Chauvet, Anne / Tualle, Jean-Michel / Ramaz, François

    Applied optics

    2019  Volume 58, Issue 8, Page(s) 1933–1940

    Abstract: Ultrasound-modulated optical tomography (UOT) is an imaging technique that couples light and ultrasound in order to perform in-depth imaging of highly scattering media. In previous work, we introduced plane wave UOT, an imaging method analogous to x-ray ... ...

    Abstract Ultrasound-modulated optical tomography (UOT) is an imaging technique that couples light and ultrasound in order to perform in-depth imaging of highly scattering media. In previous work, we introduced plane wave UOT, an imaging method analogous to x-ray tomography based on the filtered backprojection for image reconstruction. Angle-limited measurements, however, led to drastic loss of lateral spatial resolution. Here, we present a new structured ultrasonic plane wave UOT method that allows partial recovery of the resolution. For image reconstruction, we present a generalization of the Fourier slice theorem along with a generalized filtered backprojection formalism. The method is successfully tested on simulated and experimental data.
    Language English
    Publishing date 2019-03-15
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.58.001933
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

To top