Relevant bibliographies by topics / Desynchronization under constant light

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Desynchronization under constant light'

Author: Grafiati
Published: 28 June 2021
Last updated: 12 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Desynchronization under constant light.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Desynchronization under constant light"

1

Rumanova, Valentina S., Monika Okuliarova, and Michal Zeman. "Differential Effects of Constant Light and Dim Light at Night on the Circadian Control of Metabolism and Behavior." International Journal of Molecular Sciences 21, no. 15 (July 31, 2020): 5478. http://dx.doi.org/10.3390/ijms21155478.

Full text
Abstract:
The disruption of circadian rhythms by environmental conditions can induce alterations in body homeostasis, from behavior to metabolism. The light:dark cycle is the most reliable environmental agent, which entrains circadian rhythms, although its credibility has decreased because of the extensive use of artificial light at night. Light pollution can compromise performance and health, but underlying mechanisms are not fully understood. The present review assesses the consequences induced by constant light (LL) in comparison with dim light at night (dLAN) on the circadian control of metabolism and behavior in rodents, since such an approach can identify the key mechanisms of chronodisruption. Data suggest that the effects of LL are more pronounced compared to dLAN and are directly related to the light level and duration of exposure. Dim LAN reduces nocturnal melatonin levels, similarly to LL, but the consequences on the rhythms of corticosterone and behavioral traits are not uniform and an improved quantification of the disrupted rhythms is needed. Metabolism is under strong circadian control and its disruption can lead to various pathologies. Moreover, metabolism is not only an output, but some metabolites and peripheral signal molecules can feedback on the circadian clockwork and either stabilize or amplify its desynchronization.
APA, Harvard, Vancouver, ISO, and other styles
2

Poulis, J. A., F. Roelfsema, and D. van der Heide. "Circadian urinary excretion rhythms in adrenalectomized rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, no. 3 (September 1, 1986): R441—R449. http://dx.doi.org/10.1152/ajpregu.1986.251.3.r441.

Full text
Abstract:
The impact of the adrenal system on urinary rhythms was investigated in adrenalectomized (ADX) rats under various experimental conditions. During a 12:12 light-dark cycle the acrophases were shifted in ADX rats with respect to control rats. Under constant light conditions ADX rats displayed free-running rhythms, similar to those of control rats. The periods were stable in blind rats but not in rats maintained on a constant light cycle. The abrupt change in period, which occurred after approximately 8 days, suggests a stage of internal desynchronization. A 6-h delay in the administration of corticosterone to ADX rats caused a delay shift of the acrophases. A single intraperitoneal injection of corticosterone in blind free-running ADX rats caused delay or advance shifts so that we could construct phase-response curves for the various excretory rhythms. These observations indicate that the adrenals are not essential for the establishment of the urinary rhythms; however, corticosterone influences the phase setting of these rhythms. The site of action is probably the X pacemaker (controlling the body temperature rhythm), although we cannot totally exclude an additional effect on secondary (renal) oscillators.
APA, Harvard, Vancouver, ISO, and other styles
3

Guerriero, Maria Luisa, Alexandra Pokhilko, Aurora Piñas Fernández, Karen J. Halliday, Andrew J. Millar, and Jane Hillston. "Stochastic properties of the plant circadian clock." Journal of The Royal Society Interface 9, no. 69 (August 31, 2011): 744–56. http://dx.doi.org/10.1098/rsif.2011.0378.

Full text
Abstract:
Circadian clocks are gene regulatory networks whose role is to help the organisms to cope with variations in environmental conditions such as the day/night cycle. In this work, we explored the effects of molecular noise in single cells on the behaviour of the circadian clock in the plant model species Arabidopsis thaliana . The computational modelling language Bio-PEPA enabled us to give a stochastic interpretation of an existing deterministic model of the clock, and to easily compare the results obtained via stochastic simulation and via numerical solution of the deterministic model. First, the introduction of stochasticity in the model allowed us to estimate the unknown size of the system. Moreover, stochasticity improved the description of the available experimental data in several light conditions: noise-induced fluctuations yield a faster entrainment of the plant clock under certain photoperiods and are able to explain the experimentally observed dampening of the oscillations in plants under constant light conditions. The model predicts that the desynchronization between noisy oscillations in single cells contributes to the observed damped oscillations at the level of the cell population. Analysis of the phase, period and amplitude distributions under various light conditions demonstrated robust entrainment of the plant clock to light/dark cycles which closely matched the available experimental data.
APA, Harvard, Vancouver, ISO, and other styles
4

Yamanaka, Yujiro. "Basic concepts and unique features of human circadian rhythms: implications for human health." Nutrition Reviews 78, Supplement_3 (November 26, 2020): 91–96. http://dx.doi.org/10.1093/nutrit/nuaa072.

Full text
Abstract:
Abstract Most physiological functions and behaviors exhibit a robust approximately 24-hour rhythmicity (circadian rhythm) in the real world. These rhythms persist under constant conditions, but the period is slightly longer than 24 hours, suggesting that circadian rhythms are endogenously driven by an internal, self-sustained oscillator. In mammals, including humans, the central circadian pacemaker is located in the hypothalamic suprachiasmatic nucleus. The primary zeitgeber for this pacemaker is bright sunlight, but nonphotic time cues also affect circadian rhythms. The human circadian system uniquely exhibits spontaneous internal desynchronization between the sleep-wake cycle and core body temperature rhythm under constant conditions and partial entrainment of the sleep-wake cycle in response to nonphotic time cues. Experimental and clinical studies of human circadian rhythms must take into account these unique features. This review covers the basic concepts and unique features of the human circadian system, the mechanisms underlying phase adjustment of the circadian rhythms by light and nonphotic time cues (eg, physical exercise), and the effects of eating behavior (eg, chewing frequency) on the circadian rhythm of glucose metabolism.
APA, Harvard, Vancouver, ISO, and other styles
5

Madrid, J. A., F. J. Sánchez-Vázquez, P. Lax, P. Matas, E. M. Cuenca, and S. Zamora. "Feeding behavior and entrainment limits in the circadian system of the rat." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 275, no. 2 (August 1, 1998): R372—R383. http://dx.doi.org/10.1152/ajpregu.1998.275.2.r372.

Full text
Abstract:
The entrainment limits of the circadian rhythms of feeding activity were studied in Wistar rats exposed to gradually increasing and decreasing or to static light-dark cycles. In the former, the entrainment limits of feeding behavior were 22 h 10 min and 26 h 40 min. In the latter, the upper limit was higher, because rats under zeitgeber period ( t) length = 27 h ( t27) and t28 met the criteria of entrainment. The lower limit, on the other hand, was not modified because none of the t22 animals showed entrained rhythms and one-half of the t23 rats exhibited two components in their circadian feeding rhythms, one with a period of 23 h and the other free running. This 23-h component reflected not only the masking effect of light-dark cycles but also seemed a true light-entrained component. In well-synchronized animals, food intake seemed to depend more on the number of cycles that the animal experienced than on actual time lived; however, other feeding parameters, such as meal frequency and feeding duration, remained constant when expressed per 24 h, irrespective of the t cycle. These results concerning feeding duration, meal frequency, and food intake revealed that the homeostatic and circadian controls interacted to a degree that depended on the type of variable considered. In conclusion, the entrainment limits appeared much more imprecise than they were previously thought to be, because the circadian system can only be partially synchronized near its entrainment limits. The hypothesis that the rat’s circadian system is composed of multiple oscillators with different intrinsic frequencies and varying capacities for light synchronization would explain the partial desynchronization observed near the entrainment limits.
APA, Harvard, Vancouver, ISO, and other styles
6

RAMÍREZ ÁVILA, GONZALO M., JEAN-LUC GUISSET, and JEAN-LOUIS DENEUBOURG. "INFLUENCE OF UNIFORM NOISE ON TWO LIGHT-CONTROLLED OSCILLATORS." International Journal of Bifurcation and Chaos 17, no. 12 (December 2007): 4453–62. http://dx.doi.org/10.1142/s0218127407020117.

Full text
Abstract:
We study the influence of uniform noise on a system of two light-controlled oscillators (LCOs) under three different configurations: uncoupled, master–slave and mutually coupled LCOs. We find that noise can induce desynchronization via a phase transition-like phenomenon depending on the noise intensity and the characteristics of the LCOs.
APA, Harvard, Vancouver, ISO, and other styles
7

Aryal, Uma K., Jana Stöckel, Eric A. Welsh, Marina A. Gritsenko, Carrie D. Nicora, David W. Koppenaal, Richard D. Smith, Himadri B. Pakrasi, and Jon M. Jacobs. "Dynamic Proteome Analysis ofCyanothecesp. ATCC 51142 under Constant Light." Journal of Proteome Research 11, no. 2 (December 2011): 609–19. http://dx.doi.org/10.1021/pr200959x.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Liu, Ji, Klara Pendrak, Cheryl Capehart, Reiko Sugimoto, Gregor F. Schmid, and Richard A. Stone. "Emmetropisation under continuous but non-constant light in chicks." Experimental Eye Research 79, no. 5 (November 2004): 719–28. http://dx.doi.org/10.1016/j.exer.2004.08.007.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Rosenwasser, Alan M., Walter D. McCulley, Matthew C. Hartmann, Michael C. Fixaris, and John C. Crabbe. "Suppression of voluntary ethanol intake in mice under constant light and constant darkness." Alcohol 83 (March 2020): 37–46. http://dx.doi.org/10.1016/j.alcohol.2019.05.009.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Mizutani, Hiromi, Risa Tamagawa‐Mineoka, Risa Yasuike, Yoichi Minami, Kazuhiro Yagita, and Norito Katoh. "Effects of constant light exposure on allergic and irritant contact dermatitis in mice reared under constant light conditions." Experimental Dermatology 30, no. 5 (February 25, 2021): 739–44. http://dx.doi.org/10.1111/exd.14308.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Desynchronization under constant light"

1

Petrželková, Lucie. "Vývoj cirkadiánního systému potkana v podmínkách stálého světla." Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-446412.

Full text
Abstract:
The circadian system is a mechanism designed to generate circadian time and to synchronize it with the solar cycle. Its function is to adjust to behavioral and physiological function with the 24-hour period. The adjustment is performed using a so-called zeitgeber or synchronizer. The main circadian clock is in the suprachiasmatic nuclei (SCN) in the hypothalamus. Prolonged exposure of the organism to constant light conditions results in desynchronization of the circadian clock, which can lead to many pathologies. The impact of light at night on the organism has been studied for a long time, but the question of the impact of constant light on the development of the circadian system of the organism has been less studied. My thesis deals with this issue. Using RT-qPCR I investigated how the rhytm changes in the expression of selected clock genes in selected parts of the rat's brain, which has been kept in constant light sice birth. I also tested the impact of exposure to constant light on the early development of rhytm in locomotor activity later in the rat's life. Keywords: circadian system, photic entrainment, desynchronization under constant light, development, rat
APA, Harvard, Vancouver, ISO, and other styles

Books on the topic "Desynchronization under constant light"

1

Deruelle, Nathalie, and Jean-Philippe Uzan. The Lambda-CDM model of the hot Big Bang. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198786399.003.0059.

Full text
Abstract:
This chapter introduces the Lambda-CDM (cold dark matter) model. In 1948, under the impetus of George Gamow, Robert Hermann, Ralph Alpher, and Hans Bethe in particular, relativistic cosmology entered the second phase of its history. In this phase, physical processes, in particular, nuclear and atomic processes, are taken into account. This provides two observational tests of the model: primordial nucleosynthesis, which explains the origin of light nuclei, and the existence of the cosmic microwave background, and it establishes the fact that the universe has a thermal history. Study of the large-scale structure of the universe then indicates the existence of dark matter and a nonzero cosmological constant. This model, known as the Λ‎CDM model, is the standard model of contemporary cosmology.
APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "Desynchronization under constant light"

1

Hansen, U., and V. Höflich. "Efficiency of Primary Reactions of Young Beeches (Fagus Sylvatica L.) in the Understorey of Mature Beech Trees Under Lightfleck- and Constant Irradiation." In Photosynthesis: from Light to Biosphere, 4745–48. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-009-0173-5_1111.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Swendsen, Robert H. "Black-Body Radiation." In An Introduction to Statistical Mechanics and Thermodynamics, 322–30. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198853237.003.0025.

Full text
Abstract:
A black body is a perfect absorber of electromagnetic radiation. The energy spectrum was correctly calculated by Max Planck under the assumption that the energy of light waves only came in discrete multiples of a constant (called Planck’s constant) times the frequency. This was perhaps the first achievement of quantum mechanics. The derivation is presented here. The purpose of the current chapter is to calculate the spectrum of radiation emanating from a black body. The calculation was originally carried out by Max Planck in 1900 and published the following year. This was before quantum mechanics had been invented, or perhaps it could be regarded the first step in its invention.
APA, Harvard, Vancouver, ISO, and other styles
3

Guettari, Moez, and Ahmed El Aferni. "Propagation Analysis of the Coronavirus Pandemic on the Light of the Percolation Theory." In Biotechnology to Combat COVID-19 [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97772.

Full text
Abstract:
Efforts to combat the Covid-19 pandemic have not been limited to the processes of vaccine production, but they first began to analyze the dynamics of the epidemic’s spread so that they could adopt barrier measures to bypass the spread. To do this, the works of modeling, predicting and analyzing the spread of the virus continue to increase day after day. In this context, the aim of this chapter is to analyze the propagation of the Coronavirus pandemic by using the percolation theory. In fact, an analogy was established between the electrical conductivity of reverse micelles under temperature variation and the spread of the Coronavirus pandemic. So, the percolation theory was used to describe the cumulate infected people versus time by using a modified Sigmoid Boltzman equation (MSBE) and several quantities are introduced such as: the pandemic percolation time, the maximum infected people, the time constant and the characteristic contamination frequency deduced from Arrhenius equation. Scaling laws and critical exponents are introduced to describe the spread nature near the percolation time. The speed of propagation is also proposed and expressed. The novel approach based on the percolation theory was used to study the Coronavirus (Covid-19) spread in five countries: France, Italy, Germany, China and Tunisia, during 6 months of the pandemic spread (the first wave). So, an explicit expression connecting the number of people infected versus time is proposed to analyze the pandemic percolation. The reported MSBE fit results for the studied countries showed high accuracy.
APA, Harvard, Vancouver, ISO, and other styles
4

Mukhopadhyay, Sumitra, and Soumyadip Das. "Application of Nature-Inspired Algorithms for Sensing Error Optimisation in Dynamic Environment." In Nature-Inspired Algorithms for Big Data Frameworks, 124–69. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-5852-1.ch006.

Full text
Abstract:
Spectrum sensing errors in cognitive radio may occur due to constant changes in the environment like changes in background noise, movements of the users, temperature variations, etc. It leads to under usage of available spectrum bands or may cause interference to the primary user transmission. So, sensing parameters like detection threshold are required to adapt dynamically to the changing environment to minimise sensing errors. Correct sensing requires processing huge data sets just like Big Data. This chapter investigates sensing in light of Big Data and presents the study of the nature inspired algorithms in sensing error minimisation by dynamic adaptation of the threshold value. Death penalty constrained handing techniques are integrated to the genetic algorithm, particle swarm optimisation, the firefly algorithm and the bat algorithm. Based on them, four algorithms are developed for minimizing sensing errors. The reported algorithms are found to be faster and more accurate when compared with previously proposed threshold adaptation algorithms based on a gradient descend.
APA, Harvard, Vancouver, ISO, and other styles
5

G. Abrahamyan, Martin. "Vortices in Rotating and Gravitating Gas Disk and in a Protoplanetary Disk." In Vortex Dynamics Theories and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92028.

Full text
Abstract:
Nonlinear equations describing dynamics of 2D vortices are very important in the physics of the ocean and the atmosphere and in plasma physics and Astrophysics. Here linear and nonlinear 2D vortex perturbations of gravitating and light gaseous disks are examined in the geostrophic and post-geostrophic approximations. In the frame of geostrophic approximation, it is shown that the vortex with positive velocity circulation is characterized by low pressure with negative excess mass density of substance. Vortex with negative circulation has higher pressure and is a relatively tight formation with the positive excess mass density. In the post-geostrophic approximation, structures of the isolated monopole and dipole vortex (modons) solutions of these equations are studied. Two types of mass distributions in dipole vortices are found. The first type of modon is characterized by an asymmetrically positioned single circular densification and one rarefaction. The second type is characterized by two asymmetrically positioned densifications and two rarefactions, where the second densification-rarefaction pair is crescent shaped. The constant density contours of a dipole vortex in a light gas disk coincide with the streamlines of the vortex; in a self-gravitating disk, the constant density contours in the vortex do not coincide with streamlines. Possible manifestations of monopole and dipole vortices in astrophysical objects are discussed. Vortices play decisive role in the process of planet formation. Gas in a protoplanetary disk practically moves on sub-Keplerian speeds. Rigid particles, under the action of a head wind drags, lose the angular momentum and energy. As a result, the ~10 cm to meter-sized particles drift to the central star for hundreds of years. Long-lived vortical structures in gas disk are a possible way to concentrate the ~10 cm to meter sized particles and to grow up them in planetesimal. Here the effect of anticyclonic Burgers vortex on formation of planetesimals in a protoplanetary dusty disc in local approach is also considered. It is shown that the Burgers vortex with homogeneously rotating kernel and a converging radial stream of substance can effectively accumulate in its nuclear area the meter-sized rigid particles of total mass ∼1028 g for characteristic time ∼106 year.
APA, Harvard, Vancouver, ISO, and other styles
6

"to within 1% for power levels up to ten Watts. The detector size was 50 mm in diameter and its collecting solid angle is 1.6-1.7. The area of the sample was 10 square millimeters +/- 0.75 square millimeters. Finally, emission spectra are measured using a standard Fourier Transform Infrared Spectrometer on a range of samples and sample sizes. Fig. 1 SEM Micrograph of a metallic Fig. 2 Emission from a structure with photonic crystal. minimum feature size of 0.8 microns. In Fig. 2, the measured emission spectra are shown for a resistively heated sample emitting at —4 p.m. When we measure the actual power density of emission in the range of wavelengths between 3.5 and 4.5 gm. we find that the power density exceeds the value obtained from Planck's law by almost an order of magnitude. We have obtained the same result for thermally heated samples and for samples with emission peaks ranging from 1.5 gm to 6 gm. The emission peak positions are found to scale with the pitch of the lattice. The peak emission is linearly shifted to longer wavelengths for a larger lattice constant. As yet, there is no satisfactory explanation for this experimentally observed deviation from the Planck Radiation Law and its corollaries. Nonetheless, we point out that there exist sufficient differences between blackbody and tungsten photonic-crystal emitters. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL 85000." In Light Sources 2004 Proceedings of the 10th International Symposium on the Science and Technology of Light Sources, 206. CRC Press, 2004. http://dx.doi.org/10.1201/9781482269178-34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Tinker, Peter B., and Peter Nye. "The Mineral Nutrition of Single Plants in Soil." In Solute Movement in the Rhizosphere. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195124927.003.0014.

Full text
Abstract:
Earlier chapters in this book have dealt with the various components of the soil –root system. In this chapter we aim to synthesize them into a unified treatment of a single whole plant growing in soil. Solute movement and root system uptake models are still the central subject, but we must also deal with the growth of the whole plant, which provides the growing sink for the absorbed solutes, and the expanding root system through which they enter. Here we deal only with homogeneous soils and constant growing conditions, usually in pot culture, and call this ‘simplified conditions’. This is necessary in dealing with such complicated systems, so that essential principles shall not be obscured. In chapter 11 we apply these ideas, so far as it is possible, to crops and natural vegetation. Models are often referred to in this book, because the ideas and concepts are most easily and precisely formulated in this way (Nye 1992a). Here, we outline the different types of models that will be dealt with, and their relationships with each other. Readers may consult Rengel (1993) and Silberbush (1996) for recent reviews of the modelling of nutrient uptake, and Penning de Vries & Rabbinge (1995) for general crop modelling concepts. There are three basic situations: (1) Models of single or few plants growing in pots under simplified conditions in greenhouse or growth chambers, in homogeneous soils, with ample supplies of water, constant temperature, etc. (2) Models of monoculture crops. If a unit cell can be defined, only the vertical dimension need be considered, except possibly for light interception, and for radial transport around roots. These models are normally used for field situations. (3) Vegetation models with mixed species. Separation of the uptakes by the different species can be extremely difficult. If the geometrical arrangement of the species is regular, it is possible to determine a recurring unit cell, which simplifies treatment. Within each situation there is a hierarchy of complexity in the number of processes covered. All models may include water uptake as well as nutrient uptake.
APA, Harvard, Vancouver, ISO, and other styles
8

Herz, Norman, and Ervan G. Garrison. "Applications of Stable Isotopes in Archaeological Geology." In Geological Methods for Archaeology. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195090246.003.0020.

Full text
Abstract:
Isotopic ratios of elements in natural materials on the earth either have been constant in time and space or have varied as a result of radioactive decay or geochemical fractionation. Elements which show variations in isotopic abundances in different samples and the reasons for these variations have helped resolve many geological and archaeological problems. Radioactive decay has provided absolute dating clocks: for archaeology, the most useful systems have been associated with 14C, 40Ar, and U-disequilibrium series. Variations in isotopic ratios of the stable elements H, C, O, N, S, Sr, and Pb have helped solve problems of provenance, paleoenvironments, and paleodiets. The rationale for isotopic variations of individual elements will determine the types of applications to archaeological geology. The most important applications are the determinations of artifact signatures, paleodiet, and paleoenvironment. Isotopic fractionation of light elements by physical, chemical, and biological processes is controlled by those thermodynamic properties which are determined by atomic weight and electronic configuration. Thermodynamic properties of molecules that are mass and temperature dependent include energy, which decreases with decreasing temperature, and vibrational frequency, which varies inversely in proportion to the square root of the reduced mass. Easily measurable isotopic separation is generally restricted to the lighter elements, that is, with atomic weights less than 40. Because isotopic fractionation is mass dependent, the separation is greater for elements with the greater mass difference between isotopes. The greatest separation is expected for hydrogen (mass 1) versus deuterium (mass 2); the other light elements commonly have isotopic differences closer to 10%. Thus, the lighter isotopes have higher vibrational energy and their chemical bonds are more easily broken. The different reactivity of lighter versus heavier isotopes of an element is responsible for their separation during geochemical and biological processes. Thermodynamic behavior has been considered a principal cause for variations, not in isotopic abundances of the heavier elements Sr and Pb, but rather in abundances of their parent radionuclides: Rb for Sr and U and Th for Pb. Recently, however, P. Budd and others suggested that under nonequilibrium conditions, fractionation could theoretically take place among the lead isotopes.
APA, Harvard, Vancouver, ISO, and other styles
9

Rodger, Alison, and Matthew A. Ismail. "Introduction to circular dichroism." In Spectrophotometry and Spectrofluorimetry. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780199638130.003.0008.

Full text
Abstract:
Circular dichroism (CD) is the ideal technique for studying chiral molecules in solution. It is uniquely sensitive to the asymmetry of the system. These features make it particularly attractive for biological systems. CD is by definition the difference in absorption, A, of left and right circularly polarized light (CPL): . . . CD = Ae − Ar . . . . . . 1 . . . CPL has the electric field vector of the electromagnetic radiation retaining constant magnitude in time but tracing out a helix about the propagation direction. Following the optics convention we take the tip of the electric field vector of right CPL to trace out a right-handed helix in space at any instant of time (1, 2). CD spectra can in principle be measured with any frequency of electromagnetic radiation. In practice, most CD spectroscopy involves the ultraviolet-visible (UV-visible) regions of the spectrum and electronic transitions, though increasing progress is being made with measuring the CD spectra of vibrational transitions using infrared radiation. We shall limit our consideration to electronic CD spectroscopy since the practical considerations for vibrational CD differ from those for electronic CD. For randomly oriented samples, such as solutions, a net CD signal will only be observed for chiral molecules (ones that cannot be superposed on their mirror images (3)). Oriented samples of achiral molecules, such as crystals, will also give a CD spectrum unless the optical axis of the sample aligns with the propagation direction of the radiation. However, such spectra are seldom useful. CD is now a routine tool in many laboratories. The most common applications include proving that a chiral molecule has indeed been synthesized or resolved into pure enantiomers and probing the structure of biological macromolecules, in particular determining the α-helical content of proteins. Figure 3 gives an example of a CD spectrum. The key points to remember are that a CD signal is observed only at wavelengths where the sample absorbs radiation, i.e. under absorption bands, and the signal may be positive or negative depending on the handedness of the molecules in the sample and the transition being studied.
APA, Harvard, Vancouver, ISO, and other styles
10

"clash between the beauty-loving Renaissance and the he [Spenser] was quickly swept overboard because of moral Reformation. In the light of the medieval reli-his inability to write like Donne, Eliot, and Allen gious tradition examined by Tuve, Guyon destroys Tate’ (1968:2). His extended interpretation of Book the Bower because he ‘looks at the kind of complete II, The Allegorical Temper (1957), followed by essays seduction which means the final death of the soul’ on the other books, traces the changing psycholo-(31). gical or psychic development of the poem’s major If the New Critics of the 1930s to the early 1950s characters by ‘reading the poem as a poem’ (9) rather had been interested in Spenser (few were), they than as a historical document. My own book, The would not have considered his intention in writing Structure of Allegory in ‘The Faerie Queene’ (1961a), The Faerie Queene because that topic had been dis-which I regard now as the work of a historical critic missed as a fallacy. For Wimsatt and Beardsley partly rehabilitated by myth and archetypal criticism, 1954:5 (first proclaimed in 1946), ‘The poem is not examines the poem’s structure through its patterns the critic’s own and not the author’s (it is detached of imagery, an interest shared with Alastair Fowler, from the author at birth and goes about the world Spenser and the Numbers of Time (1964), and by beyond his power to intend about it or control it)’. Kathleen Williams, Spenser’s ‘Faerie Queene’: The So much for any poet’s intention, conscious or World of Glass (1966). unconscious, realized or not. Not that it would have In any history of modern Spenser criticism – for a mattered much, for the arbiter of taste at that time, general account, see Hadfield 1996b – Berger may T.S. Eliot, had asked rhetorically: ‘who, except schol-serve as a key transitional figure. In a retrospective ars, and except the eccentric few who are born with glance at his essays on Spenser written from 1958 to a sympathy for such work, or others who have delib-1987, he acknowledges that ‘I still consider myself erately studied themselves into the right apprecia-a New Critic, even an old-fashioned one’ who tion, can now read through the whole of The Faerie has been ‘reconstructed’ by New Historicism Queene with delight?’ (1932:443). In Two Letters, (1989:208). In Berger 1988:453–56, he offers a per-Spenser acknowledges that the gods had given him sonal account of his change, admitting that as a New the gift to delight but never to be useful (Dii mihi, Critic he had been interested ‘in exploring complex dulce diu dederant: verùm vtile numquam), though representations of ethico-psychological patterns’ he wishes they had; and, in the Letter to Raleigh, he apart from ‘the institutional structures and discourses recognizes that the general end of his poem could be that give them historical specificity’. Even so, he had achieved only through fiction, which ‘the most part allowed that earlier historical study, which had been of men delight to read, rather for variety of matter, concerned with ‘historical specificity’, was ‘solid and then for profite of the ensample’ (10). As a conse-important’. For the New Historicist Louis Adrian quence, he addresses his readers not by teaching them Montrose, however, earlier historical scholarship didactically but rather through delight. It follows that ‘merely impoverished the text’ (Berger 1988:8), and if his poem does not delight, it remains a closed book. he is almost as harsh towards Berger himself, com-Several critics who first flourished in the 1950s and plaining that his writings ‘have tended to avoid direct 1960s responded initially to Spenser’s words and confrontations of sociopolitical issues’, though he imagery rather than to his ideas, thought, or histor-blames ‘the absence of a historically specific socio-ical context. One is Donald Cheney, who, in Spenser’s political dimension’ on the time they were written – Image of Nature (1966), read The Faerie Queene a time when ‘the sociopolitical study of Spenser was ‘under the intensive scrutiny which has been applied epitomized by the pursuit of topical identifications or in recent decades to metaphysical lyrics’, seeking the cataloguing of commonplaces’ (7). In contrast, out ‘ironic, discordant impulses’, ‘rapidly shifting the New Historicism, of which he is the most elo-allusions’, and the poet’s ‘constant insistence upon quent theorist, sees a work embedded – i.e. intrins-the ambiguity of his images’ (7, 17, 20). Another is ically, inextricably fixed – not in history generally, Paul Alpers, whose The Poetry of ‘The Faerie Queene’ and certainly not in ‘cosmic politics’ that Thomas (1967) demonstrated that individual stanzas of the Greene 1963:406 claims to be the concern of all epics, poem may be subjected to very intense scrutiny. A but in a historically specific sociopolitical context. third, the most influential of all, is Harry Berger, Jr, (For further comments on their clash, see Hamilton." In Spenser: The Faerie Queene, 25. Routledge, 2014. http://dx.doi.org/10.4324/9781315834696-23.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Desynchronization under constant light"

1

Xu, Xiao-Ming, Wen-Qing Zhu, Qiang Wang, Zhi-Lin Zhang, and Xue-Yin Jiang. "Study on the degradation of sealed organic light-emitting diodes under constant current." In High Density Packaging (ICEPT-HDP). IEEE, 2009. http://dx.doi.org/10.1109/icept.2009.5270644.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Moon, Swapnil, I. Joga Rao, and Fangda Cui. "Modeling Circular Shear in Shape Memory Polymers With Triple Shape Effect Subjected to Crystallization Under Constant Shear." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50203.

Full text
Abstract:
The capacity of a material to sense its environment and to change its shape on demand in a predefined way has tremendous technological significance for a wide variety of application areas. Shape memory polymers (SMPs) belong to this category of smart materials as they have the ability to undergo a shape change in a predetermined manner under the influence of an external stimulus. SMPs can recover their permanent shape after undergoing large deformation to a temporary shape on exposure to external triggers such as light, PH values and heat. Thermally induced SMPs are first generation SMPs and have been widely recognized. Crystallizable SMPs are a class of thermally induced SMPs whose temporary shape is due to formation of crystalline phases, and they will revert back to their permanent shape when the crystallization phase is melted through heating. Traditional crystallizable SMPs can only perform dual-shape memory cycles and this limits applications of crystallizable SMPs. Recently SMPs with triple shape effect have been reported that can switch from a second temporary shape to the first temporary shape and from there to the permanent shape under stimulation by heat. Our research focuses on modeling the mechanical behavior of these SMPs with triple-shape effect. The framework used in developing the model is built upon the theory of multiple natural configurations [3]. In order to model the mechanics associated with these polymers different stages of the shape fixation and recovery cycle and different phases of the material during this cycle need to be characterized. This includes developing a model for the amorphous phase and the subsequent semi-crystalline phases with different stress free states and melting of these phases. The model subsequently has been used to simulate results for a typical deformation cycle involving circular shear.
APA, Harvard, Vancouver, ISO, and other styles
3

Lourenc¸o, Marcelo Igor, Theodoro A. Netto, Neilon S. Silva, Paulo Emi´lio Valada˜o de Miranda, and Joa˜o Carloes Ribeiro Pla´cido. "Experimental and Numerical Evaluations of Aluminum Drill Pipes Under Cyclic Loads." In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92160.

Full text
Abstract:
Experimental program and numerical analyses were carried out to investigate the fatigue mechanisms of aluminum drill pipes designed and manufactured in compliance with ISO 15546. Material mechanical properties, including S-N curve, were determined through small-scale tests on specimens cut from actual drill pipes. Full-scale experiments were also performed in laboratory. Initially, the tool-joint assembly procedure was actually performed to monitor the resulting strain/stress level in selected points of the aluminum pipe. Three full-scale aluminum drill pipe specimens were then fatigue tested under combined cyclic bending and constant axial tension. In parallel, a finite element model of the tool-joint region, where two drill pipe specimens failed in the fatigue tests, was developed. The model was first used to reproduce the tool-joint assembly. Then, the physical experiments were simulated numerically in order to obtain the actual stress distribution in this region. Good correlation between full-scale and small-scale fatigue tests was obtained by adjusting the strain/stress levels monitored in the full-scale tests in light of the numerical simulations.
APA, Harvard, Vancouver, ISO, and other styles
4

Nomura, Yuichiro, Makoto Higuchi, Yasuhide Asada, and Katsumi Sakaguchi. "The Modified Rate Approach Method to Evaluate Fatigue Life Under Synchronously Changing Temperature and Strain Rate in Elevated Temperature Water in Austenitic Stainless Steel." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-2679.

Full text
Abstract:
The fatigue life of steel of light water reactor (LWR) in elevated temperature water is affected by the composition of the environmental water, decreasing strain rate and increasing temperature. The effects of these parameters on fatigue life reduction have been investigated experimentally. One problem to be discussed is the fact that the previous studies which leaded main results on the environmental effects were generally executed by experimental parameters constant. On the other hand, in an actual plant, such parameters as temperature and strain rate are changing transient. In order to evaluate fatigue damage in an actual plant on the basis of experimental results under constant temperature and constant strain rate conditions, the modified rate approach method was developed. The study has conducted as a part of the EFT project in order to evaluate the applicability of the modified rate approach to the case that LWR environment. The applicability of a modified rate approach method to the case where temperature and strain rate varied simultaneously was discussed in the previous paper(1). In order to confine the applicability under extended condition, the tests of which conditions were different from those of the previous study were conducted. The accuracy of modified rate approach is same level of the result of previous paper.
APA, Harvard, Vancouver, ISO, and other styles
5

Eason, Ernest, and Raj Pathania. "Crack Tip Strain Rate Models for Environmentally-Assisted Fatigue Crack Growth in Light Water Reactor Environments." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63640.

Full text
Abstract:
This paper demonstrates the feasibility of using theoretically-motivated crack tip strain rate (CTSR) models to estimate environmentally-assisted fatigue (EAF) crack growth rate (CGR) in light water reactor (LWR) environments. Four models, each combining one of two CTSR expressions with one of two theoretical derivations from Faraday’s Law, were fitted to measured CGR data under dynamic loadings. The four models were compared with each other and with experimental crack growth data from examples where various austenitic stainless steel base metals and nickel-alloy welds were tested in LWR environments under EAF, periodic partial unloading (PPU) with various hold times, loading gradients with increasing and decreasing stress intensity factor K (±dK/da), and constant K loading. All four models produced good fits to the data on some examples, and the models using the newer derivation performed well on all examples. Default model parameters and an equation for the distance from the crack tip at which strain rate is estimated were successful in simplifying the application of the models. Both variable effects and measured CGR were well modeled. Advantages and issues of theoretically-based CTSR models are presented.
APA, Harvard, Vancouver, ISO, and other styles
6

Mei, Joseph S., Esmail R. Monazam, and Lawerence J. Shadle. "The Mapping of Flow Regimes for a Light Material: Cork." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-014.

Full text
Abstract:
A series of experiments was conducted in the 0.3-meter diameter circulating fluidized bed test facility at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL). Cork, the bed material used in this study, is a coarse, light material, with a particle density of 189 kg/m3 and a mean diameter of 1007 μm. Fluidizing this material in ambient air provides approximately the same gas to solids density ratio as coal and coal char in a pressurized gasifier. Furthermore, the density ratio of cork to air under ambient conditions is similar to the density ratio of coal to gas at the gasification and pressurized fluidized bed combustion environment. The purpose of this study is to generate reliable data to validate the mathematical models currently under development at NETL. Using such coarse, light material can greatly facilitate the computation of these mathematical models. This paper presents and discusses data for the operating flow regimes of dilute-phase, fast-fluidization, and dense-phase transport by varying the solid flux (Gs) at a constant gas velocity (Ug). Data are presented by mapping the flow regime for coarse cork particles in a ΔP/ ΔL-Gs-Ug plot. The coarse cork particles exhibited different behavior than the measurements on heavier materials found in published literature, such as alumina, sand, FCC, and silica gel. Stable operation can be obtained at a fixed riser gas velocity that is higher than the transport velocity (e.g. at Ug = 3.2 m/sec), even though the riser is operating within the fast fluidization flow regime. Depending upon the solid influx, the riser can also be operated at dilute-phase or dense-phase flow regimes. Experimental data were compared to empirical correlations in published literature for flow regime boundaries, and solid fractions in the upper-dilute and the lower-dense regions of a fast fluidization flow regime. Comparisons of measured data show rather poor agreement with these empirical correlations. Xu et al. (2000) have observed this lack of agreement in their study of the effect of bed diameter on the saturation carrying capacity. The basis of empirical correlations depends on bed diameter and particle type, and are generally not well understood.
APA, Harvard, Vancouver, ISO, and other styles
7

Barua, Bipul, Subhasish Mohanty, William K. Soppet, Saurindranath Majumdar, and Krishnamurti Natesan. "Fatigue Modeling of 508 LAS Under Variable Amplitude Loading: A Mechanistic Based Analytical Approach." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65876.

Full text
Abstract:
A Chaboche-based evolutionary cyclic plasticity model is proposed to model the elastic-plastic behavior of 508 Low Alloy Steel (LAS), a commonly used material for Light Water Reactor (LWR), under variable amplitude loading. A novel parameter estimation technique is developed to incorporate the amplitude dependency of the material behavior into the earlier developed time-dependent material models based on constant amplitude fatigue test data. The resulting new material model can be referred as time-dependent-amplitude-independent material models. Variable amplitude fatigue tests under different environmental conditions (in air and pressurized water reactor (PWR) coolant water at 300°C) are analytically/mechanistically modeled. The analytical modeling results show that the time-dependent-amplitude-independent material parameters are able to capture the stress-strain state under variable amplitude fatigue loading. The developed model and reported material parameters can be utilized for more accurate stress analysis of safety-critical reactor components under real-life loading scenarios with variable/random loading transients. Recently a report on related 508 LAS material characterization work has been published by Argonne National Laboratory [1]. In this work a summary of the related work is presented.
APA, Harvard, Vancouver, ISO, and other styles
8

Azetsu, Akihiko, Youhei Nagashima, and Kei Yamamoto. "Combustion Characteristics of Diesel Spray Under Low O2 Concentration Condition." In ASME 2013 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icef2013-19155.

Full text
Abstract:
The spray combustion of diesel fuel under conditions of very low ambient O2 concentrations was examined in this study. The detailed combustion characteristics were evaluated using two different sets of experimental apparatuses. A high-temperature, high-pressure combustion vessel with dual observation windows was employed to visualize the spray flame. The sequential images were obtained by using a high-speed color video camera and were analyzed using the two color method to quantify the temporal variation of the two dimensional distribution of soot temperature and KL factor. Both the ambient O2 concentration and the CO2 mixing ratio were varied as experimental parameters. A second constant volume vessel with a smaller internal volume was also employed as an experimental apparatus to conduct analyses of heat release rates based on temporal variations of pressure. Based on a series of systematic experiments, we confirmed that O2 concentration is the primary factor affecting both the ignition delay and combustion period, while the level of CO2 mixing has little effect. Decreasing O2 concentrations were associated with delays in the appearance of the luminous flame following the onset of light emission from OH radicals. The heat release rate study showed the possibility of the existence of endothermic reactions during this period. The flame temperature was observed to decrease as the O2 concentration decreased and as the CO2 ratio increased, resulting in reduced NOx emissions. The amount of soot inside the flame initially increased with decreasing O2 concentrations, but then decreased starting at an O2 concentration of approximately 11%, such that minimal amounts of soot were generated at very low O2 levels. Both visual observations and emissions measurements confirmed that the simultaneous reduction of NOx, soot and CO can be successfully achieved under very low O2 concentrations.
APA, Harvard, Vancouver, ISO, and other styles
9

Li, Huiyu, Xufang Zhang, and Hornsen Tzou. "Frequency Control of Light-Activated Shape Memory Polymer Laminated Beams: Characterization and Experiments." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59818.

Full text
Abstract:
Light-activated shape memory polymers (LaSMPs) exhibit stiffness variations when exposed to ultraviolet (UV) lights. Thus, LaSMP could manipulate structural natural frequencies with UV light exposures when laminated on structures. This study aims to experimentally demonstrate the effectiveness of LaSMP frequency control of a flexible beam. The natural frequency of a three-layered Euler-Bernoulli beam composed of LaSMP, adhesive tape and the flexible beam is analyzed and its frequency formulation exhibits the LaSMP stiffness influence. As the LaSMP adopted in this study is a new spiropyran based composition, a generic Young’s modulus model is proposed and then simplified to model the present LaSMP composition. To make sure the experiment is carried out in a homogenous light field, the light intensities of the UV surface light source at different positions are tested. The temperature change of the LaSMP sample under UV exposures is also measured. The time constant of the reverse reaction and the threshold intensity of the reverse reaction are measured. LaSMP Young’s modulus variation is tested with a uniaxial tension experiment. The constitutive model of LaSMP’s Young’s modulus is validated by experimental data. With these preparations, the LaSMP laminated flexible beam model is exposed to the UV lights and its natural frequencies are identified with a data acquisition and analysis system. The maximum natural frequency variation ratio achieves 5.67%. Comparing both theoretical and experimental data of natural frequency control, this study also validates the LaSMP Young’s modulus constitutive model.
APA, Harvard, Vancouver, ISO, and other styles
10

Chen, Y., B. Alexandreanu, and A. S. Rao. "Cracking Behavior of a Decommissioned Material in Light Water Reactor Environment." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21141.

Full text
Abstract:
Abstract The performance of structural materials is critical for the safe and economic operation of light water reactors. During power operation, reactor core internal materials are exposed to aggressive corrosive coolant environment, vigorous thermal/mechanical loading, and intensive neutron irradiation. Such severe service conditions can activate and enhance a wide range of degradation processes, leading to deteriorated material properties and service performance. To ensure the structural integrity and functionality of nuclear reactor components, material degradation and damage mechanisms must be understood and managed adequately. It has been recognized that there are knowledge and data gaps in the existing information and technical bases for long-term operation and aging management. In particular, post-irradiation data on fracture toughness and crack growth rate are lacking. In this work, irradiated materials harvested from a decommissioned reactor are studied for their cracking susceptibility and fracture resistance as a function of irradiation dose. The materials are a Type 304 stainless steel sectioned from the baffle plates of a pressurized water reactor after 38 years of service. Miniature compact-tension specimens about 6.5-mm thick are machined from these materials with different levels of irradiation damage, ranging from < 1 to ∼50 dpa depending on the original locations with respect to the reactor core. Crack growth rate and fracture toughness J-R curve tests are performed in a low-corrosion-potential environment at ∼315°C. All samples behave similarly under cyclic loading, and no deteriorated corrosion fatigue behavior can been seen in the test environment. Under constant loads, most of samples show no elevated crack growth rates, suggesting an adequate stress corrosion cracking resistance for these irradiated samples in the test environment. An unstable cracking behavior was observed occasionally where step-wise crack advances upon load increases can be seen. The effect of neutron irradiation is evident on fracture toughness. With the increasing dose, the J-R curve declined constantly, and became very shallow at high doses. It is evident that this baffle plate material has been severely embrittled by neutron irradiation. In addition, an unexpected fully IG morphology has been observed for the all high-dose samples fractured at room temperature in air atmosphere. The occurrence of this brittle fracture in the absence of aggressive environment confirmed a high degree of embrittlement of this material resulting from its service exposure to neutron irradiation.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Desynchronization under constant light' for particular source types:
Journal articles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography