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Author |
Walmsley, L.; Hanna, L.; Mouland, J.; Martial, F.; West, A.; Smedley, A.R.; Bechtold, D.A.; Webb, A.R.; Lucas, R.J.; Brown, T.M. |
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Title |
Colour As a Signal for Entraining the Mammalian Circadian Clock |
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Journal Article |
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Year |
2015 |
Publication |
PLoS Biology |
Abbreviated Journal |
PLoS Biol |
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Volume |
13 |
Issue |
4 |
Pages  |
e1002127 |
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Keywords |
Animals; biology; color; circadian disruption; animal models; mouse models; Suprachiasmatic Nucleus; Photoperiod; twilight |
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Abstract |
Twilight is characterised by changes in both quantity (“irradiance”) and quality (“colour”) of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue-yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision. |
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Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom |
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PLOS |
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English |
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English |
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1544-9173 |
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PMID:25884537 |
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no |
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Call Number |
IDA @ john @ |
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1152 |
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Author |
Escobar, C.; Salgado-Delgado, R.; Gonzalez-Guerra, E.; Tapia Osorio, A.; Angeles-Castellanos, M.; Buijs, R.M. |
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Title |
Circadian disruption leads to loss of homeostasis and disease |
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Journal Article |
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Year |
2011 |
Publication |
Sleep Disorders |
Abbreviated Journal |
Sleep Disord |
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Volume |
2011 |
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Pages |
964510 |
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Keywords |
Human Health |
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Abstract |
The relevance of a synchronized temporal order for adaptation and homeostasis is discussed in this review. We present evidence suggesting that an altered temporal order between the biological clock and external temporal signals leads to disease. Evidence mainly based on a rodent model of “night work” using forced activity during the sleep phase suggests that altered activity and feeding schedules, out of phase from the light/dark cycle, may be the main cause for the loss of circadian synchrony and disease. It is proposed that by avoiding food intake during sleep hours the circadian misalignment and adverse consequences can be prevented. This review does not attempt to present a thorough revision of the literature, but instead it aims to highlight the association between circadian disruption and disease with special emphasis on the contribution of feeding schedules in circadian synchrony. |
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Departamento de Anatomia, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, 04360 Mexico City, DF, Mexico |
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English |
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ISSN |
2090-3553 |
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PMID:23471148; PMCID:PMC3581131 |
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no |
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Call Number |
LoNNe @ kagoburian @ |
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745 |
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Author |
Ban, Y.; Cao, C.; Shao, X. |
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Title |
Assessment of scan-angle dependent radiometric bias of Suomi-NPP VIIRS day/night band from night light point source observations |
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Journal Article |
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Year |
2015 |
Publication |
Proc. SPIE 9607, Earth Observing Systems XX, 2015 |
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960727 |
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Keywords |
Remote sensing; Suomi NPP; VIIRS DNB; calibration |
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Abstract |
The low gain stage of VIIRS Day/Night Band (DNB) on Suomi-NPP is calibrated using onboard solar diffuser. The calibration is then transferred to the high gain stage of DNB based on the gain ratio determined from data collected along solar terminator region. The calibration transfer causes increase of uncertainties and affects the accuracy of the low light radiances observed by DNB at night. Since there are 32 aggregation zones from nadir to the edge of the scan and each zone has its own calibration, the calibration versus scan angle of DNB needs to be independently assessed. This study presents preliminary analysis of the scan-angle dependence of the light intensity from bridge lights, oil platforms, power plants, and flares observed by VIIRS DNB since 2014. Effects of atmospheric path length associated with scan angle are analyzed. In addition, other effects such as light changes at the time of observation are also discussed. The methodology developed will be especially useful for JPSS J1 VIIRS due to the nonlinearity effects at high scan angles, and the modification of geolocation software code for different aggregation modes. It is known that J1 VIIRS DNB has large nonlinearity across aggregation zones, and requires new aggregation modes, as well as more comprehensive validation. |
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Univ. of Maryland, College Park, USA |
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SPIE |
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English |
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English |
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no |
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Call Number |
IDA @ john @ |
Serial |
1259 |
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Author |
Lee, S.; Wang, W.; Cao, C. |
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Title |
JPSS-1 VIIRS DNB nonlinearity and its impact on SDR calibration |
Type |
Journal Article |
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Year |
2015 |
Publication |
Proc. SPIE 9607, Earth Observing Systems XX, 2015 |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
960717 |
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Keywords |
Remote sensing; Suomi NPP; VIIRS DNB; JPSS-1; calibration |
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Abstract |
During JPSS-1 VIIRS testing at Raytheon El Segundo, a larger than expected radiometric response nonlinearity was discovered in Day-Nigh Band (DNB). In addition, the DNB nonlinearity is aggregation mode dependent, where the most severe non-linear behavior are the aggregation modes used at high scan angles (<~50 degree). The DNB aggregation strategy was subsequently modified to remove modes with the most significant non-linearity. We characterized the DNB radiometric response using pre-launch tests with the modified aggregation strategy. The test data show the DNB non-linearity varies at each gain stages, detectors and aggregation modes. The non-linearity is most significant in the Low Gain Stage (LGS) and could vary from sample-to-sample. The non-linearity is also more significant in EV than in calibration view samples. The HGS nonlinearity is difficult to quantify due to the higher uncertainty in determining source radiance. Since the radiometric response non-linearity is most significant at low dn ranges, it presents challenge in DNB cross-stage calibration, an critical path to calibration DNB’s High Gain Stage (HGS) for nighttime imagery. Based on the radiometric characterization, we estimated the DNB on-orbit calibration accuracy and compared the expected DNB calibration accuracy using operational calibration approaches. The analysis showed the non-linearity will result in cross-stage gain ratio bias, and have the most significant impact on HGS. The HGS calibration accuracy can be improved when either SD data or only the more linearly behaved EV pixels are used in cross-stage calibration. Due to constrain in test data, we were not able to achieve a satisfactory accuracy and uniformity for the JPSS-1 DNB nighttime imagery quality. The JPSS-1 DNB nonlinearity is a challenging calibration issue which will likely require special attention after JPSS-1 launch. |
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NOAA National Environmental Satellite, Data, and Information Service, USA |
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SPIE |
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English |
Summary Language |
English |
Original Title |
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no |
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Call Number |
IDA @ john @ |
Serial |
1262 |
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Author |
Salgado-Delgado, R.; Tapia Osorio, A.; Saderi, N.; Escobar, C. |
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Title |
Disruption of circadian rhythms: a crucial factor in the etiology of depression |
Type |
Journal Article |
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Year |
2011 |
Publication |
Depression Research and Treatment |
Abbreviated Journal |
Depress Res Treat |
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Volume |
2011 |
Issue |
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Pages |
839743 |
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Keywords |
Human Health |
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Abstract |
Circadian factors might play a crucial role in the etiology of depression. It has been demonstrated that the disruption of circadian rhythms by lighting conditions and lifestyle predisposes individuals to a wide range of mood disorders, including impulsivity, mania and depression. Also, associated with depression, there is the impairment of circadian rhythmicity of behavioral, endocrine, and metabolic functions. Inspite of this close relationship between both processes, the complex relationship between the biological clock and the incidence of depressive symptoms is far from being understood. The efficiency and the timing of treatments based on chronotherapy (e.g., light treatment, sleep deprivation, and scheduled medication) indicate that the circadian system is an essential target in the therapy of depression. The aim of the present review is to analyze the biological and clinical data that link depression with the disruption of circadian rhythms, emphasizing the contribution of circadian desynchrony. Therefore, we examine the conditions that may lead to circadian disruption of physiology and behavior as described in depressive states, and, according to this approach, we discuss therapeutic strategies aimed at treating the circadian system and depression. |
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Departamento de Biologia Celular y Fisiologia, Instituto de Investigaciones Biomedicas, Universidad Nacional Autonoma de Mexico, 04306 Mexico, DF, Mexico |
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English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2090-1321 |
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Notes |
PMID:21845223; PMCID:PMC3154570 |
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no |
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Call Number |
LoNNe @ christopher.kyba @ |
Serial |
524 |
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