The Effect of a Biological Clock on the Developmental Rate of Drosophila Pupae

1965 ◽  
Vol 42 (2) ◽  
pp. 323-337
Author(s):  
JANET E. HARKER
Keyword(s):  
Biological Clock ◽  
Bright Light ◽  
Developmental Rate ◽  
Time Of Day ◽  
Time Interval ◽  
Light Cycle ◽  
Continuous Darkness ◽  
Pupal Development ◽  
Wide Range ◽  
Three Stages

1. A study of the course of pupal development in two strains of Drosophila melanogaster has been made in an attempt to establish the factors affecting the time of adult eclosion. 2. The time taken to complete three stages of pupal development has been measured for pupae entering each stage at each particular hour of the day when insects were kept in 12 hr. light:12 hr. darkness, 12 hr. bright light: 12 hr. dim light, or in continuous darkness. 3. The duration of each stage, in both strains, is affected by the time of day, relative to the light cycle, at which the stage is entered. The duration of each stage for pupae kept in continuous darkness is affected by the time of day at which the stage is entered, relative to the light cycle to which they had been exposed as larvae. 4. The time-interval curves for all three stages of any one strain take the same form. 5. Because of the very wide range of developmental rates, dependent upon the time within the light cycle at which each stage begins, a population in which the larvae all pupate within a 24 hr. period will continue to produce adult flies over several days. 6. The eclosion rhythm is a population effect and does not reflect the phasing of individuals to a dawn eclosion; the majority of adults emerge at dawn because of the summation effect of circadian rhythms of development at earlier stages.

The Effect of Photoperiod on the Developmental Rate of Drosophila Pupae

1965 ◽  
Vol 43 (3) ◽  
pp. 411-423
Author(s):  
JANET E. HARKER
Keyword(s):  
Dark Period ◽  
Developmental Rate ◽  
Time Of Day ◽  
Constant Darkness ◽  
Time Interval ◽  
Simple Relationship ◽  
Light Cycle ◽  
Rate Of Development ◽  
Eclosion Rhythm ◽  
Developmental Rates

1. The time taken for Drosophila melanogaster to complete three stages of pupal development has been measured for pupae entering each stage at each particular hour of the day in cycles of 12 hr. light:12 hr. darkness, 4 hr. light:20 hr. darkness, 18 hr. light:6 hr. darkness. Similar measurements have been made for insects in which the larvae were subjected to the light cycles but the pupae remained in constant darkness. 2. The duration of each stage is affected by the time of day, relative to the light cycle, at which the stage is entered. When pupae are in constant darkness the developmental rate of each stage is affected by the time of day at which the stage is entered relative to the particular light cycle to which the larval stage had been exposed. 3. The eclosion rhythm, which arises as a summation effect of rhythms of development at earlier stages, may become bimodal in light cycles with suitable photofractions. 4. The rate of development of a pupa entering a stage during the light period is related to the time-interval since the light-on signal; the preceding dark period has no effect. 5. The developmental rate of pupa entering a stage during the dark period is affected by the time-interval since the light-off signal, but may also be affected by the previous light-on signal although there is no simple relationship between them. 6. As the developmental rates are maintained in constant darkness it is concluded that the rate of development is affected by factors following a diurnal rhythm. The form of the rhythm is determined by both light-on and light off signals, but the timing of the rhythm is determined by the two signals acting independently of each other.

Nonphotic entrainment of the human circadian pacemaker

1998 ◽  
Vol 274 (4) ◽  
pp. R991-R996 ◽  
Author(s):  
Elizabeth B. Klerman ◽  
David W. Rimmer ◽  
Derk-Jan Dijk ◽  
Richard E. Kronauer ◽  
Joseph F. Rizzo ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Light Exposure ◽  
Core Body Temperature ◽  
Biological Clock ◽  
Bright Light ◽  
Circadian Pacemaker ◽  
Temperature Rhythms ◽  
Blind Individuals ◽  
Nonphotic Entrainment ◽  
Core Body

In organisms as diverse as single-celled algae and humans, light is the primary stimulus mediating entrainment of the circadian biological clock. Reports that some totally blind individuals appear entrained to the 24-h day have suggested that nonphotic stimuli may also be effective circadian synchronizers in humans, although the nonphotic stimuli are probably comparatively weak synchronizers, because the circadian rhythms of many totally blind individuals “free run” even when they maintain a 24-h activity-rest schedule. To investigate entrainment by nonphotic synchronizers, we studied the endogenous circadian melatonin and core body temperature rhythms of 15 totally blind subjects who lacked conscious light perception and exhibited no suppression of plasma melatonin in response to ocular bright-light exposure. Nine of these fifteen blind individuals were able to maintain synchronization to the 24-h day, albeit often at an atypical phase angle of entrainment. Nonphotic stimuli also synchronized the endogenous circadian rhythms of a totally blind individual to a non-24-h schedule while living in constant near darkness. We conclude that nonphotic stimuli can entrain the human circadian pacemaker in some individuals lacking ocular circadian photoreception.

scholarly journals A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sebastiano Piccolroaz ◽  
Bieito Fernández-Castro ◽  
Marco Toffolon ◽  
Henk A. Dijkstra
Keyword(s):  
Turbulent Mixing ◽  
Meteorological Data ◽  
Time Of Day ◽  
Monthly Basis ◽  
Lake Garda ◽  
Standardized Protocol ◽  
Wide Range ◽  
Buoyancy Driven Convection ◽  
Monitoring Activity ◽  
Additional Monitoring

AbstractA multi-site, year-round dataset comprising a total of 606 high-resolution turbulence microstructure profiles of shear and temperature gradient in the upper 100 m depth is made available for Lake Garda (Italy). Concurrent meteorological data were measured from the fieldwork boat at the location of the turbulence measurements. During the fieldwork campaign (March 2017-June 2018), four different sites were sampled on a monthly basis, following a standardized protocol in terms of time-of-day and locations of the measurements. Additional monitoring activity included a 24-h campaign and sampling at other sites. Turbulence quantities were estimated, quality-checked, and merged with water quality and meteorological data to produce a unique turbulence atlas for a lake. The dataset is open to a wide range of possible applications, including research on the variability of turbulent mixing across seasons and sites (demersal vs pelagic zones) and driven by different factors (lake-valley breezes vs buoyancy-driven convection), validation of hydrodynamic lake models, as well as technical studies on the use of shear and temperature microstructure sensors.

scholarly journals Fear of light: On the cause and remediation of photophobia

2021 ◽  
Vol 53 (5) ◽  
pp. 395-404
Author(s):  
A Wilkins
Keyword(s):  
Spatial Pattern ◽  
Bright Light ◽  
Visual Discomfort ◽  
Wide Range

Photophobia (fear of light) occurs in a wide range of ophthalmic, neurological and behavioural conditions, the most common of which is migraine. The visual discomfort associated with migraine can occur not only in response to bright light but also flicker, spatial pattern and colour. The principles that underlie the discomfort are explored and methods to reduce it are proposed.

scholarly journals Mathematical modeling shows that ball-rolling dung beetles can use dances to avoid competition

2021 ◽  
Author(s):  
Zhanyuan Yin ◽  
Leif Zinn-Brooks
Keyword(s):  
Mathematical Modeling ◽  
Optimal Strategy ◽  
Rolling Direction ◽  
Dung Beetles ◽  
Time Interval ◽  
Angular Deviation ◽  
Ball Rolling ◽  
Wide Range

Abstract Ball-rolling dung beetles shape a portion of dung into a ball and roll it away from the dung pile for later burial and consumption. These beetles perform dances (rotations and pauses) atop their dung balls in order to choose an initial rolling direction and to correct their rolling direction (reorient). Previous mathematical modeling showed that dung beetles can use reorientation to move away from the dung pile more efficiently. In this work, we study if reorientation can help beetles avoid competition (i.e., avoid having their dung balls captured), and if so, under what circumstances? This is investigated by implementing a model with two different type of beetles, a roller with a dung ball and a searcher which seeks to capture that dung ball. We show that reorientation can help rollers avoid searchers in a wide range of conditions, but that there are some circumstances in which rolling without reorienting can be a beetle's optimal strategy. We also show that rollers can minimize the probability that their dung ball is captured without making precise measurements of the time interval between dances or the angular deviation for dances.

scholarly journals Comparative verification in complex topography

2021 ◽  
Author(s):  
Jonas Bhend ◽  
Jean-Christophe Orain ◽  
Vera Schönenberger ◽  
Christoph Spirig ◽  
Lionel Moret ◽  
...  
Keyword(s):  
Weather Forecasting ◽  
Absolute Error ◽  
Time Of Day ◽  
Probabilistic Forecasts ◽  
Wide Range ◽  
Direct Model ◽  
Forecasting System ◽  
The Mean ◽  
Update Frequency ◽  
Core Activity

<p>Verification is a core activity in weather forecasting. Insights from verification are used for monitoring, for reporting, to support and motivate development of the forecasting system, and to allow users to maximize forecast value. Due to the broad range of applications for which verification provides valuable input, the range of questions one would like to answer can be very large. Static analyses and summary verification results are often insufficient to cover this broad range. To this end, we developed an interactive verification platform at MeteoSwiss that allows users to inspect verification results from a wide range of angles to find answers to their specific questions.</p><p>We present the technical setup to achieve a flexible yet performant interactive platform and two prototype applications: monitoring of direct model output from operational NWP systems and understanding of the capabilities and limitations of our pre-operational postprocessing. We present two innovations that illustrate the user-oriented approach to comparative verification adopted as part of the platform. To facilitate the comparison of a broad range of forecasts issued with varying update frequency, we rely on the concept of time of verification to collocate the most recent available forecasts at the time of day at which the forecasts are used. In addition, we offer a matrix selection to more flexibly select forecast sources and scores for comparison. Doing so, we can for example compare the mean absolute error (MAE) for deterministic forecasts to the MAE and continuous ranked probability scores of probabilistic forecasts to illustrate the benefit of using probabilistic forecasts.</p>

scholarly journals PHILOSOPHICAL ATTITUDES OF THE EARLY WORKS OF P. TYCHYNA AS AN OBJECT OF MODERNIST-POSTMODERN MYTH CREATION

2019 ◽  
pp. 5-11
Author(s):  
H. V. Vdovychenko
Keyword(s):  
Cultural Development ◽  
Soviet Period ◽  
The Political ◽  
Political Environment ◽  
Philosophical Foundations ◽  
Early Twenty ◽  
Wide Range ◽  
Three Stages ◽  
Systematic Development ◽  
Almost All

The article classifies and highlights three stages spanning the last hundred years – pre-Soviet, Soviet and post-Soviet, of research and mythol- ogization of the life and creation of P.Tychyna, using the example of studying the philosophical attitudes of his early work in the Ukrainian state, the Ukrainian SSR, Ukraine and abroad. The specifics of the formation of the mentioned stages during 1918 – 2019 were systematically considered on materials, including little-known, studies of more than fifty representatives of domestic and foreing tychynology, as well as a wide range of materi- als of the poetic, prosaic, scientific-journalistic and epistolary heritage of P. Tychyna and his contemporary colleagues. In the context of this review an attempt was made of critical interdisciplinary analysis – cultural and philosophical and literary, of the ideological foundations and the results of the modernist and postmodern mythologization of the early creativity of P. Tychyna as the leading creator and symbol of Ukrainian Modernist and Socialist-Realistic literature and, in general, cultural development. The article identifies three leading aspects of defining and studying the philosophical foundations of P. Tychyna's early work in the twentieth – early twenty first centuries: 1) the absence of the formulation and systematic development of the topic in P. Tychyna studies, except for the initial attempts at each of its stages, so far; 2) the narrow specialty of individual attempts at such research, first of all, almost entirely literary or linguistic, but not professional philosophical and cultural philosophical; 3) the dominant conditionality of the major achievements of almost all of these studies, mainly the Soviet period, the political environment of the development of national humanities and, as a consequence, the consistent isolationist-Soviet-anti-European mythology of P. Tychyna's creative figure and heritage. In view of this, the development of this topic in the context of an interdisciplinary, critically-demythologizing scientific search, formed in the contemporary P. Tychyna studies, has been identified as promising.

Psychiatric side effects induced by supraphysiological doses of combinations of anabolic steroids correlate to the severity of abuse

2006 ◽  
Vol 21 (8) ◽  
pp. 551-562 ◽  
Author(s):  
Thomas A. Pagonis ◽  
Nikiforos V. Angelopoulos ◽  
George N. Koukoulis ◽  
Christos S. Hadjichristodoulou
Keyword(s):  
Side Effects ◽  
Anabolic Steroids ◽  
Linear Regression Analysis ◽  
Control Group ◽  
Time Interval ◽  
Psychological Consequences ◽  
Psychometric Instruments ◽  
Wide Range ◽  
Significant Difference ◽  
Psychiatric Side Effects

AbstractObjectiveThe objective of our study was to evaluate the psychological consequences of real-world AAS use in athletes abusing such agents, in comparison with a placebo and control group of comparable athletes, while correlating the severity of abuse with the side effects observed. The hypothesis tested by the study was that the use of AAS induces a wide range of psychological side effects whose impact and emergence is dependent upon the severity of the abuse.DesignThe study includes a substantial group of AAS abusing athletes and two more groups demographically similar to the first, one composed of athletes not using any substance and a placebo group. All athletes were stratified according to the severity of AAS abuse. Psychometric instruments were applied to all athletes in specific time intervals, dependent to the AAS abusers' regimens, providing us with a final psychological profile that was to be compared to the pre-study profile. All results were comparable (within and between groups) for statistically significant differences and correlated to the severity of the abuse. Homogeneity of all groups was safeguarded by random doping controls, monitoring of drug levels and analysis of all self obtained drugs by method of liquid chromatography/mass spectrometry. All athletes were provided with a common exercise and dietary regime, so common training and nutritional conditions were achieved.MethodsWe studied a cohort of 320 body-building, amateur and recreational athletes, of whom 160 were active users of AAS (group C), 80 users administering placebo drugs (group B) and 80 not abusing any substance (Group A). Group C athletes were stratified according to AAS abuse parameters, thus providing us with three subgroups of “light, medium and heavy abuse”. Athletes of groups A and B were included in a “no abuse” subgroup. The psychometric instruments used were the Symptoms Check List-90 (SCL-90) and the Hostility and Direction of Hostility Questionnaire (HDHQ). The psychometric evaluations took place within a time interval of 13 months. Statistical analysis was performed by using the Mann–Whitney/Wilcoxon two-sample non-parametric test (Kruskal–Wallis test for two groups) for data that were not normally distributed and Linear regression analysis was used to ascertain the correlation between severity of use and escalation of side effects.ResultsThe study showed a statistically significant increase in all psychometric subscales recorded in group C, and no statistically significant difference in group C and A. There was a significant increase in the scorings of group C for all subscales of SCL-90 and HDHQ. Correlation of abuse severity and side effects showed that there was a statistical significant increase in Δ values of all SCL-90 and HDHQ subscales that escalated from light abuse to medium and heavy abuse/consumption patterns.ConclusionsThe results of the study suggest that the wide range of psychiatric side effects induced by the use of AAS is correlated to the severity of abuse and the force of these side effects intensifies as the abuse escalates.

Functionalization of Gold Nanoparticles with Monosaccharide Mannose

2021 ◽  
pp. 6281-6284
Author(s):  
Sambit Dash ◽  
Pragna Rao ◽  
Ullas Kamath ◽  
Aparna R Pai ◽  
Prasanna Kumar Reddy Gayam ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Phase Transfer ◽  
Colour Change ◽  
Cost Effective ◽  
Biomedical Sciences ◽  
Size Dependent ◽  
Nanoparticles Dispersion ◽  
Wide Range ◽  
Three Stages ◽  
Transfer Method

Gold nanoparticles have found a wide range of application in biomedical sciences. Unique properties of these metal nanoparticles include surface plasmon resonance and size dependent colour change. Various molecules have been functionalized on the gold nanoparticles surface but carbohydrates have garnered attention due to their properties and their role in living systems. However certain challenges make carbohydrate-gold nanoparticles association difficult to obtain and stabilize. This study was carried out to chemically remodel gold nanoparticles by adding a monosaccharide mannose to its surface. A modified phase transfer method was used to synthesize gold nanoparticles. The surface of the nanoparticles was fixed with cyanuric chloride to serve as a linker. Mannose was then linked to the linker molecule. All three stages of the process, gold nanoparticles, and gold nanoparticles with linker and gold nanoparticles with the carbohydrate were analyzed for size and stability. Zeta potential and UV-vis data exhibited stable gold nanoparticles dispersion, successful binding of linker molecule as well as the carbohydrate. This study shows a simple, cost-effective and robust method of glycomodification of gold nanoparticles surface which can further find use in wide ranging applications.

Prometheus

2018 ◽  
Author(s):  
Andrew C. Scott
Keyword(s):  
Volcanic Activity ◽  
Human Interaction ◽  
Time Interval ◽  
C4 Grasses ◽  
Fossil Plants ◽  
Natural Fire ◽  
Lightning Strikes ◽  
Wide Range ◽  
Cooked Meat ◽  
Vegetation And Climate

It is sometimes said that humans were born of fire. While a wide range of animal species interact with fire, we appear to be the only species to have learned to tame it, and more importantly to make it. There is evidence that early humans were aware of fire and may have exploited naturally occurring fire, but only later did they control and manage it. Human interaction with fire must have proceeded through various levels, the first of which can be described as the opportunistic phase. In this phase, natural fire may have been exploited to help in hunting, for example. When, how, and why did this happen? It is widely agreed that our story begins in Africa. It is here that we see the evolution of hominins, a group of related genera that include the Australopithecines and later the genus Homo. How common would fire have been in the environments in which they lived? We already know from the study of fossil plants, as well as isotope data, that there were important changes in both the vegetation and climate over the past 10 million years. It is also during this time interval that hominins emerged from apes. Through the Oligocene and Miocene (30–8 million years ago), Africa was largely covered by tropical rainforest, where fire was present but infrequent, started both by lightning strikes and volcanic activity. As the climate began to dry and C4 grasses spread at the end of the Miocene Epoch, around 8 million years ago, habitats became more open. Fire became more frequent, and from an animal perspective would have become more visible, not just from flames but also smoke. Frequent fire in the landscape would have had many consequences for the early hominins, not just because game was more easily killed, but burned animals (naturally cooked meat) would have made a useful addition to the diet, and the new flush of growth following fire would also have attracted large herds of herbivores. Fire may have been conserved through adding fuel, including dung, which is slow burning.

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