4,208 research outputs found
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
sj-docx-1-jbr-10.1177_07487304231176936 – Supplemental material for Impact of Light Schedules and Model Parameters on the Circadian Outcomes of Individuals
No full textSupplemental material, sj-docx-1-jbr-10.1177_07487304231176936 for Impact of Light Schedules and Model Parameters on the Circadian Outcomes of Individuals by Caleb Mayer, Olivia Walch, Daniel B. Forger and Kevin Hannay in Journal of Biological Rhythms</p
A Period2 Phosphoswitch Regulates and Temperature Compensates Circadian Period
No full textPeriod (PER) protein phosphorylation is a critical regulator of circadian period, yet an integrated understanding of the role and interaction between phosphorylation sites that can both increase and decrease PER2 stability remains elusive. Here, we propose a phosphoswitch model, where two competing phosphorylation sites determine whether PER2 has a fast or slow degradation rate. This mathematical model accurately reproduces the three-stage degradation kinetics of endogenous PER2. We predict and demonstrate that the phosphoswitch is intrinsically temperature sensitive, slowing down PER2 degradation as a result of faster reactions at higher temperatures. The phosphoswitch provides a biochemical mechanism for circadian temperature compensation of circadian period. This phosphoswitch additionally explains the phenotype of Familial Advanced Sleep Phase (FASP) and CK1 epsilon(tau) genetic circadian rhythm disorders, metabolic control of PER2 stability, and how drugs that inhibit CK1 alter period. The phosphoswitch provides a general mechanism to integrate diverse stimuli to regulate circadian period.
Seasonal timing and interindividual differences in shiftwork adaptation
No full textMillions of shift workers in the U.S. face an increased risk of depression, cancer, and metabolic disease, yet individual responses to shift work vary widely. We find that a conserved biological system of morning and evening oscillators, which evolved for seasonal timing, may contribute to these interindividual differences. In this study, we analyze seasonality in medical interns working shifts, revealing that summer-winter variation correlates with increased circadian misalignment after shift work. Mathematical modeling suggests that seasonal timing influences the rate of adaptation to new schedules, predicting differential effects on morning and evening oscillators. Additionally, we examine genetic polymorphisms linked to seasonality in animals and find that human variants can impact how quickly circadian rhythms respond to schedule changes. Based on our findings, we hypothesize that the vast interindividual differences in shift work adaptation-critical for shift worker health-can in part be explained by biological mechanisms for seasonal timing.
Predicting circadian phase in community-dwelling later-life adults using actigraphy data
No full textThe accurate estimation of circadian phase in the real-world has a variety of applications, including chronotherapeutic drug delivery, reduction of fatigue, and optimal jet lag or shift work scheduling. Recent work has developed and adapted algorithms to predict time-consuming and costly laboratory circadian phase measurements using mathematical models with actigraphy or other wearable data. Here, we validate and extend these results in a home-based cohort of later-life adults, ranging in age from 58 to 86 years. Analysis of this population serves as a valuable extension to our understanding of phase prediction, since key features of circadian timekeeping (including circadian amplitude, response to light stimuli, and susceptibility to circadian misalignment) may become altered in older populations and when observed in real-life settings. We assessed the ability of four models to predict ground truth dim light melatonin onset, and found that all the models could generate predictions with mean absolute errors of approximately 1.4 h or below using actigraph activity data. Simulations of the model with activity performed as well or better than the light-based modelling predictions, validating previous findings in this novel cohort. Interestingly, the models performed comparably to actigraph-derived sleep metrics, with the higher-order and nonphotic activity-based models in particular demonstrating superior performance. This work provides evidence that circadian rhythms can be reasonably estimated in later-life adults living in home settings through mathematical modelling of data from wearable devices.
Entraining stimulus and corresponding limit cycle of the Jewett-Forger-Kronauer model.
No full text<p>The top plot shows the entraining stimulus (LD-cycle) and the leftmost plot, the entrained limit cycle corresponding to this stimulus. Here pink corresponds to day and black to night. The middle plot shows the oscillations in the first coordinate of the entrained limit cycle. The last plot shows the phase of periodic stimulus or, equivalently, of the entrained oscillator. All significant features are labeled with the appropriate notation (See <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003523#s4" target="_blank">Methods</a>, or Notation in supplemental <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003523#pcbi.1003523.s016" target="_blank">text S1</a>).</p
Histoire de la Deuxième Guerre Mondiale (1992-1997) (04). Conférence de Daniel Cordier (1) - face B
No full textSéminaire organisé et enregistré par l'IHTP (Paris), entre 1992 et 1997 ; sous la direction de Jean-Pierre Azéma et Dominique Veillon. Conférence de Daniel Cordier
The process of re-entrainment to a phase shift of the Jewett-Forger-Kronauer Model.
No full text<p>The top plot shows the entraining stimulus (LD-cycle) to the oscillator, plotted on a log scale, shifted by hours at time 0. The light level increases from 100 lux before time 0 to ( = 10,000 lux) after time 0. In this case ( = 7 hours) is positive, so the schedule is advanced. The middle plot shows the oscillations in first coordinate of the model. The entrained oscillator before the phase shift is shown with a solid line, and the dotted line shows how the oscillator would behave were it entrained to the shifted stimulus. The solid line after time 0 shows the process of re-entrainment to the phase shift. The last plot shows the phase of the stimulus or, equivalently, of the entrained oscillator. Notice that the shift takes place when the phase of the stimulus (and therefore of the entrained oscillator) is ( = 7 hours). All significant features are labeled with the appropriate notation (See <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003523#s4" target="_blank">Methods</a>, or Setting up the Problem in supplemental <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003523#pcbi.1003523.s016" target="_blank">text S1</a>).</p
Optimal schedules for re-entrainment to 8 and 12 hour shifts of the LD-cycle.
No full text<p>Predicted core body temperature minima (CBTmin, magenta triangles) are plotted against the pattern of optimal exposure to bright light (200 lux–10,000 lux, yellow), moderate light (100 lux, white), and darkness (0 lux, black). Predicted CBTmin under noisy light levels (See supplemental <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003523#pcbi.1003523.s001" target="_blank">figure S1</a>), with circadian period randomly sampled from an experimentally measured distribution <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003523#pcbi.1003523-Czeisler2" target="_blank">[18]</a>, is plotted for 20 hypothetical subjects (blue circles). The timing of entrained CBTmin in the new time zone is indicated by the dotted line. Circadian amplitude at CBTmin is indicated by the brightness of the markers, with white corresponding to zero amplitude. The subjects are initially entrained to a 16∶8 LD-cycle in moderate light. At day 0 the schedule shift occurs. Optimal schedules are grouped in rows by maximum admissible bright light level (yellow), and in columns by effected phase shift. Figures (<b>A</b>), (<b>B</b>), (<b>C</b>) use a maximum light level of 10,000 lux; (<b>D</b>), (<b>E</b>), (<b>F</b>) use 1000 lux; (<b>G</b>), (<b>H</b>), (<b>I</b>) use 500 lux; (<b>J</b>), (<b>K</b>), (<b>L</b>) use 200 lux; (<b>M</b>), (<b>N</b>), (<b>O</b>) use 100 lux. Figures (<b>A</b>), (<b>D</b>), (<b>G</b>), (<b>J</b>), (<b>M</b>) are optimal schedules for an 8-hour delay; (<b>B</b>), (<b>E</b>), (<b>H</b>), (<b>K</b>), (<b>N</b>) a 12-hour shift; (<b>C</b>), (<b>F</b>), (<b>I</b>), (<b>L</b>), (<b>O</b>) an 8-hour advance.</p
- …
