Hours Of Darkness Research Articles

Editorial: Zooplankton and Nekton: Gatekeepers of the Biological Pump

Editorial on the Research Topic Zooplankton and Nekton: Gatekeepers of the Biological Pump Zooplankton and nekton organisms create and destroy particles in manifold ways. They feed on the diverse components of the plankton community and on detrital matter. They disaggregate these components, but also repackage them into fecal pellets. Zooplankton and nekton thereby contributes to the attenuation, but also to the export of vertically settling particles. Many zooplankton and nekton organisms also ascend to the surface layer of the ocean at dusk to feed during the dark hours, and return to midwater at the break of dawn. This diurnal vertical migration (DVM) shuttles organic matter from the surface ocean to deeper layers, where it is metabolized and excreted. This active flux (as opposed to the passive flux of sinking particles) can contribute substantially to the biological pump, the downward export of carbon and nutrients into the oceans interior. Due to their multiple roles in oceanic particle dynamics, zooplankton and nekton organisms can actually be considered the gatekeepers of the biological pump. Several articles in this Research Topic deal with the contribution of zooplankton and nekton-mediated active flux to the total export of organic matter. Using biomass and enzyme transport system (ETS) assessments of respiratory flux for both mesozooplankton and micronekton communities, Hernandez-Leon et al. estimated the total active transport of carbon (respiration, excretion, mortality, and egestion) along a transect in the Atlantic from the Canary Islands to Brazil. They found that active flux by these communities ranged from 25 to 80% of the total particulate organic carbon export at 150 m depth and that the importance of active flux increased with increasing surface productivity. Kwong et al. compared biomass, diel vertical migration, and active flux of mesozooplankton and micronekton across a range of mesoscale eddy structures along the east-coast of Australia during winter and spring. They found that although all eddy regimes had similar integrated biomass of mesozooplakton and micronekton, the organisms in the individual eddies had different migratory behavior, which resulted in contrasting importance of active flux. Kiko et al. assessed the impact of mesozooplankton DVM on elemental cycling at three stations in the Eastern Tropical North Atlantic. They found that approximately 31 to 41% of the total nitrogen loss from the upper 200 m of the water column was attributable to DVM mediated fluxes. They also suggest that gut flux-the flux created by migrators when they evacuate their gut at DVM-depth-and migrator mortality at DVM-depth contribute to an Intermediate Particle Maximum. In their study conducted in the Peruvian upwelling system (which features a severe midwater oxygen minimum zone), Kiko and Hauss concluded that the metabolic suppression

“If Necessary for Years, If Necessary Alone”: History, Memory, and Fiction in Contemporary Representations of Dunkirk

A seemingly impossible task, the evacuation of the majority of the British Expeditionary Force (more than 300,000 men) from the shores of Dunkirk, besieged by the German forces, represented a symbol of hope in a moment in which the British Empire was suffering crushing defeats in Europe as well as in Asia. The myth of the ‘finest hour’ of the British people, both spontaneously generated from below and directed from above by the government, has been a central topic of the British propaganda during and after the war, and it still possesses a strongly evocative power over new generations of artists. In recent years, several movies (Atonement, 2007, Dunkirk, 2017, Darkest Hour, 2017) have represented the evacuation of Dunkirk, oscillating between propagandistic rhetoric and a problematization of the memory of the war. By analyzing these films, this article shows how post-war generations have appropriated the cultural memory of Dunkirk as a way of restaging an ideal of Britishness and at the same time as a controversial attempt to update it by highlighting the divisions of class and ideology among British society and the army.

Physiological Responses of Tomato and Cucumber Seedlings under Different Light–Dark Cycles

Tomato and cucumber seedlings were grown in a growth chamber to evaluate the effects of different cycles of light–dark exposure conditions (T0 (control treatment) (1 cycle of 24 h distributed in 18 h of light exposure and six hours of dark), T1 (two cycles of 12 h distributed in nine hours of light exposure and three hours of dark) and T2 (three cycles of eight hours distributed in six hours of light exposure and two hours of dark) on growth, nutrient status, pigment concentration and physiological changes. Total dry weight showed different behaviors in both species, since in tomato the total dry weight remained unchanged under varying light–dark cycles, whereas in cucumber seedlings there was a clear decrease compared to the control treatment. In both species, plants grown under T2 showed the best water content. Nitrogen, P and K content—as well as partitioning in the different organs of the plants—displayed different patterns under varying cycles of light–dark conditions in both species. Chlorophyll (b and a + b) concentration decreased significantly in both species in T1 and T2 compared to the control treatment (T0). At physiological level, the concentration of total soluble sugars and proline in leaf showed the highest value in the control treatment with 18 h of light and six hours of dark.

Fotoperiyodun Acanthoscelides obtectus Say (Coleoptera: Bruchidae)’un gelişim süresi, eşey oranı ve verimine etkisi

In the trials, the influence of photoperiod on the development time, sex ratio, and fecundity of Acanthoscelides obtectus were examined. The trials were carried out in five different photoperiod regimes including 0L:24D [continuous darkness (CD)], 6L:18D (6 hours of light, 18 hours of dark), 12L:12D (12 hours of light, 12 hours of dark), 18L:6D (18 hours of light, 6 hours of dark), 24L:0D [continuous light (CL)] with a temperature of 25±2 ºC and 60±5% relative humidity. The shortest pre-adult development time was determined under CD conditions. While the development period lasted 26.33±0.88 days under CD conditions, it lasted for 35.33±0.66 days under CL conditions. Although the sex ratio did not differ much, CL conditions were in favor of males. The lowest female fecundity was determined under CL and 18L:6D conditions. Fecundity did not differ significantly under CD and 6L:18D, while it decreased significantly under 12L:12D, 18L:6D, and CL conditions. Especially, when CL and CD were compared with each other, statistically significant difference was observed.

Phytochrome-imposed inhibition of PIF7 activity shapes photoperiodic growth in Arabidopsis together with PIF1, 3, 4 and 5.

Under photoperiodic conditions, Arabidopsis thaliana seedling growth is inhibited in long days (LDs), but promoted under the extended nights of short days (SDs). This behavior is partly implemented by phytochrome (phy)-imposed oscillations in the abundance of the growth-promoting, phy-interacting bHLH transcription factors PHY-INTERACTING FACTOR 1 (PIF1), PIF3, PIF4 and PIF5 (PIF quartet or PIFq). However, the observation that a pifq mutant is still stimulated to elongate when given a phy-inactivating end-of-day far-red pulse (EODFR), suggests that additional factors are involved in the phy-mediated suppression of growth during the subsequent dark period. Here, by combining growth-analysis of pif7 single- and higher-order mutants with gene expression analysis under SD, LD, SD-EODFR, and LD-EODFR, we show that PIF7 promotes growth during the dark hours of SD, by regulating growth-related gene expression. Interestingly, the relative contribution of PIF7 in promoting growth is stronger under EODFR, whereas PIF3 role is more important under SD, suggesting that PIF7 is a prominent target of phy-suppression. Indeed, we show that phy imposes phosphorylation and inactivation of PIF7 during the light hours in SD, and prevents full dephosphorylation during the night. This repression can be lifted with an EODFR, which correlates with increased PIF7-mediated gene expression and elongation. In addition, our results suggest that PIF7 function might involve heterodimerization with PIF3. Furthermore, our data indicate that a pifqpif7 quintuple mutant is largely insensitive to photoperiod for hypocotyl elongation. Collectively, the data suggest that PIF7, together with the PIFq, is required for the photoperiodic regulation of seasonal growth.

Future liasing of the lockdown during COVID-19 pandemic: The dawn is expected at hand from the darkest hour

The lockdown during COVID-19 pandemic has converted the world into new experimental laboratories, which may reveal temporal or spatial comparative analysis data. However, some startling information is gathered in terms of reduced premature mortality cases associated with air and water quality improvement, enhanced e-learning on a broader platform, work from home, and successful e-health. The decline in vehicular density on roads and congestion leads to reduced energy consumption and associated greenhouse gases (GHG) and other pollutants emission. The lockdown has also been identified as a possible emergency measure to combat severe air pollution episodes. Similarly, industrial pollution has been recognized as one of the primary causes of water resource pollution and would, therefore, bring change in policy vis-à-vis groundwater pollution control. Our findings suggest that the results of successful e-learning and work from home would be a permanent shift from conventional modes in the near future due to a drastic reduction in socio-economic cost. Our critical analysis also highlights that with such temporary lockdown measures acute/chronic ill-effects of anthropogenic perturbations on planet earth can be effectively estimated through sociocultural, socioeconomical and socio-political/sociotechnological nexus.

Embracing Their Prey at That Dark Hour: Common Cuttlefish (Sepia officinalis) Can Hunt in Nighttime Light Conditions.

Cuttlefish are highly efficient predators, which strongly rely on their anterior binocular visual field for hunting and prey capture. Their complex eyes possess adaptations for low light conditions. Recently, it was discovered that they display camouflaging behavior at night, perhaps to avoid detection by predators, or to increase their nighttime hunting success. This raises the question whether cuttlefish are capable of foraging during nighttime. In the present study, prey capture of the common cuttlefish (Sepia officinalis) was filmed with a high-speed video camera in different light conditions. Experiments were performed in daylight and with near-infrared light sources in two simulated nightlight conditions, as well as in darkness. The body of the common cuttlefish maintained a velocity of less than 0.1 m/s during prey capture, while the tentacles during the seizing phase reached velocities of up to 2.5 m/s and accelerations reached more than 450 m/s2 for single individuals. There was no significant difference between the day and nighttime trials, respectively. In complete darkness, the common cuttlefish was unable to catch any prey. Our results show that the common cuttlefish are capable of catching prey during day- and nighttime light conditions. The common cuttlefish employ similar sensory motor systems and prey capturing techniques during both day- and nighttime conditions.

The effect of varying laboratory conditions on the locomotor activity of the nocturnal Namaqua rock mouse (Micaelamys namaquensis) and the diurnal Four-striped grass mouse (Rhabdomys dilectus)

Rodents are the most common laboratory animals all over the world, however, most studies on the effects of laboratory conditions on the behavior and physiology of the study animals have been performed on traditional laboratory animals. We investigated the effects of environmental enrichment, lighting conditions and ambient temperature cycles on the locomotor activity of wild trapped, nocturnal Namaqua rock mice and diurnal Four-striped grass mice. When considering the general activity of the two species, the diurnal species showed more variability in locomotor activity than the nocturnal species. Cage enrichment differentially affected the intensity of the locomotor activity in the two species. Despite a decrease in activity, the diurnal species showed more structured rhythms in an enriched cage. Twilight conditions changed the behavior of both species, the active time of the nocturnal animal was contracted to the completely dark hours of the light cycle, while the active time of the diurnal species was extended in the longer daylight hours. The natural light appears to stabilize the entrainment of the diurnal species. The natural ambient temperature cycle caused changes in intensity of activity, but reinforced entrainment in both species. These results show that changes in laboratory housing conditions can affect the activity of captive wild animals and that these effects are species specific. By increasing our understanding of the effects of different environmental factors on the outcomes of experiments, both the results obtained, and the welfare of the captive animals may be improved.

Photoperiod effects on carcass traits, meat quality, and stress response in heart and lung of broilers

This study evaluated effects of photoperiod treatments on slaughter and carcass traits, meat quality, indicators of oxidative stress, and heat shock protein 70 (Hsp70) levels of lung and heart tissues in broilers. Five hundred Ross 308 broiler chicks were used. The treatments consisted of 23 hours of continuous light and one hour of darkness (23L1D), four hours of light followed by two hours of darkness (4L2D), eight hours of light and four hours of darkness (8L4D), and 16 hours of light and eight hours of darkness (16L8D). After 42 days, two birds from each replicate were slaughtered. Birds that had been subjected to 16L8D had lower slaughter, carcass, and breast weights than the other treatments. Significant correlations were observed for slaughter, carcass and breast weights and white stripe. At 10 min post mortem, the pH of the breast was the highest in 23L1D. Breasts from birds subjected to 23L1D and 16L8D had most fat and least protein, while white striping was not different among treatments. The 4L2D treatment resulted in the highest lung glutathione (GSH) concentration. Malondialdehyde (MDA) and GSH concentrations in the heart tissues of broilers from 8L4D and 4L2D were greater than those from 23L1D and 16:8. Glutathione peroxidase (GSH-Px) and superoxide dismutase concentrations were greatest for birds subjected to 16L8D. Heat shock protein 70 was lowest in lung and heart from birds subjected to 8L4D. Thus, shorter and more frequent periods of darkness can be recommended for welfare with little compromise in performance.
 Keywords: carcass quality, heat shock protein 70, oxidative stress, white stripe

Influence of Season and Day Length on Production and Reproductive Traits and Egg Characteristics of the Guinea Fowl (Numida meleagris)

Aims: This study was conducted to determine the influence of season and day length on production traits, egg characteristics, fertility and hatchability of laying Guinea fowls (Numida meleagris).
 Study Design: Factorial design was used for the study.
 Place and Duration of Study: The study was conducted at the Poultry Unit of the Department of Animal Science Education, University of Education, Winneba, Ghana, Mampong campus from September, 2015 to December, 2016.
 Methodology: Four (4) hens and one (1) male per replicate and fifteen (15) per treatment were each subjected to 12 hours of artificial light and 12 hours of darkness (12L:12D), 14hours of artificial light and 10 hours of darkness (14L:10D), 16hours of artificial light and 8 hours of darkness (16L:8D) and 18hours of artificial light and 6 hours of darkness (18L:6D). Each group was replicated three times and reared in three seasons (Dry-December-March, Major rains-April-July and Minor rains-August-November) in a 3x4 factorial experiment. Data were analyzed using General Linear Model procedure of SAS.
 Results: Results showed that egg weight, hen-day egg production and egg mass increased (P= .05) with increasing day length. Similar results were observed for yolk height, yolk weight and albumin height. Most production traits, egg characteristics, fertility and hatchability attained the highest (P= .05) value in the major rainy season.
 Conclusion: It was concluded that day length of 14-16 hours is sufficient for improved laying performance and that breeding cycles should be planned to coincide with the major rainy season.

Possible effects of priming on germination performance of white clover (Trifolium repens L.) seeds in hypothermia condition

The aim of the study is investigate the effects of hidropriming on germination performance of white clover (Trifolium repens) seedsunder cold stress, optimum temperature and dark condition. The seeds were germinated applying hidropriming with dH2O in different periods (2, 4, 6, 8, 16, 18, 20, 22, 24 and 48 hours) in dark at 4 oC. The study was applied in according to randomized controlled trials as 4 replications to measure radicular lengths, germination rate and homogeneity parameter in the seeds. The results of the study was indicated that radicle length, germination rate, rate and the homogeneity parameter were positive and statistically significant (P<0.001) comparing with control group in short period (2 and 4 hours). On the other hand radicle length, germination rate, the homogeneity parameter were found negative and statistically significant when compare with control group in the other periods (P<0.001). In addition, this study was discussed possible physiological effects to the priming process implemented with dH2O in hypothermia condition at white clover seeds.

Characterization of Total OH Reactivity in a Rapeseed Field: Results from the COV3ER Experiment in April 2017

Croplands remain poorly studied ecosystems in terms of total hydroxyl radical (OH) reactivity, especially when compared to forests. As part of the COV3ER project, total OH reactivity (ROH), defined as the total loss rate of OH due to its reaction with reactive species in the atmosphere, was characterized in a rapeseed field (Grignon, France) during the blooming season in April 2017. Measurements were performed in a dynamic chamber as well as in ambient air using the Comparative Reactivity Method (CRM). Complementary measurements of organic (including a proton transfer reaction quadrupole ion–time of flight mass spectrometry, PTRQi-ToFMS) and inorganic compounds were also performed in order to calculate the expected OH reactivity and evaluate the missing fraction. Measured ROH varied diurnally in the dynamic chamber (mROHchamber) with maxima around 20 to 30 s−1 at midday and minima during dark hours, following the variability of the enclosed branch VOCsrapeseed, which is light- and temperature-dependent. Oxygenated VOCs were the major compounds emitted by the rapeseed crop. However, in terms of contribution to OH reactivity, isoprene accounted for 40% during the daytime, followed by acetaldehyde (21%) and monoterpenes (18%). The comparison between mROHchamber and calculated ROH (cROHchamber) exhibited little or no difference during dark hours, whereas a maximum difference appeared around midday, highlighting a significant missing fraction (46% on average during daytime) mainly related to biogenic temperature- and/or light-dependent emissions.

Reproductive management of the transitional mare

The mare is a seasonally polyoestrous long-day breeder with a physiological breeding season lasting from April–October in the Northern Hemisphere. The hypothalamic-pituitary-gonadal axis in the mare is subject to a circannual endogenous rhythm that is primarily regulated by day length. Increasing ambient photoperiod in the spring alters the pattern of melatonin secretion. The resulting stimulation of hypothalamic gonadotropin-releasing hormone secretion triggers pituitary follicular stimulating hormone release and follicular growth. Exposure of mares in deep anoestrus to a stimulatory photoperiod remains the most successful method of advancing the first ovulation of the season. The most commonly used lighting regimen is providing a fixed length of 15–16 hours of light exposure and 8–9 hours of dark, with a minimum light intensity in a stable of 100-lux (100–200 watt incandescent bulb). Other methods include using an additional 2.5 hours of light beginning at sunset and a pulse lighting system, providing 1 hour of light, 9.5–10.5 hours after the onset of darkness, during the photosensitive phase. Alternatively, the EquilumeTMlight masks provide a unilateral LED light source emitting 50 lux of blue-light directly to the eye during the hours after dusk (until 11 pm). Mares that have not been maintained under lights, or that have been exposed to ineffective light therapy, may require therapeutic hormonal intervention to advance the onset of the first ovulation of the season. Many hormone protocols involving progestins, GnRH, dopamine agonists and recombinant luteinising hormone/follicle stimulating hormone have been studied with variable results. Therapy is typically more effective when started either in late transitional mares or following a period of stimulatory artificial photoperiod.

Reproductive management of the transitional mare

The mare is a seasonally polyoestrous long-day breeder with a physiological breeding season lasting from April–October in the Northern Hemisphere. The hypothalamic-pituitary-gonadal axis in the mare is subject to a circannual endogenous rhythm that is primarily regulated by day length. Increasing ambient photoperiod in the spring alters the pattern of melatonin secretion. The resulting stimulation of hypothalamic gonadotropin-releasing hormone secretion triggers pituitary follicular stimulating hormone release and follicular growth. Exposure of mares in deep anoestrus to a stimulatory photoperiod remains the most successful method of advancing the first ovulation of the season. The most commonly used lighting regimen is providing a fixed length of 15–16 hours of light exposure and 8–9 hours of dark, with a minimum light intensity in a stable of 100-lux (100–200 watt incandescent bulb). Other methods include using an additional 2.5 hours of light beginning at sunset and a pulse lighting system, providing 1 hour of light, 9.5–10.5 hours after the onset of darkness, during the photosensitive phase. Alternatively, the EquilumeTM light masks provide a unilateral LED light source emitting 50 lux of blue-light directly to the eye during the hours after dusk (until 11 pm). Mares that have not been maintained under lights, or that have been exposed to ineffective light therapy, may require therapeutic hormonal intervention to advance the onset of the first ovulation of the season. Many hormone protocols involving progestins, GnRH, dopamine agonists and recombinant luteinising hormone/follicle stimulating hormone have been studied with variable results. Therapy is typically more effective when started either in late transitional mares or following a period of stimulatory artificial photoperiod.

Quantitative Study of Dual Circadian Oscillator Models under Different Skeleton Photoperiods.

The daily proportion of light and dark hours (photoperiod) changes annually and plays an important role in the synchronization of seasonal biological phenomena, such as reproduction, hibernation, and migration. In mammals, the first step of photoperiod transduction occurs in the suprachiasmatic nuclei (SCN), the circadian pacemaker that also coordinates 24-h activity rhythms. Thus, in parallel with its role in annual synchronization, photoperiod variation acutely shapes day/night activity patterns, which vary throughout the year. Systematic studies of this behavioral modulation help understand the mechanisms behind its transduction at the SCN level. To explain how entrainment mechanisms could account for daily activity patterns under different photoperiods, Colin Pittendrigh and Serge Daan proposed a conceptual model in which the pacemaker would be composed of 2 coupled, evening (E) and morning (M), oscillators. Although the E-M model has existed for more than 40 years now, its physiological bases are still not fully resolved, and it has not been tested quantitatively under different photoperiods. To better explore the implications of the E-M model, we performed computer simulations of 2 coupled limit-cycle oscillators. Four model configurations were exposed to systematic variation of skeleton photoperiods, and the resulting daily activity patterns were assessed. The criterion for evaluating different model configurations was the successful reproduction of 2 key behavioral phenomena observed experimentally: activity psi-jumps and photoperiod-induced changes in activity phase duration. We compared configurations with either separate light inputs to E and M or the same light inputs to both oscillators. The former replicated experimental results closely, indicating that the configuration with separate E and M light inputs is the mechanism that best reproduces the effects of different skeleton photoperiods on day/night activity patterns. We hope this model can contribute to the search for E and M and their light input organization in the SCN.

Moon light and the activity patterns of Baird’s tapir in the Calakmul region, Southern México

The Baird’s tapir (Tapirella bairdii) is an endangered species throughout its distribution area, however many aspects of its biology and ecology have been poorly studied, due to its evasive behavior and low densities. The goal of this study was to evaluate the activity patterns of T. bairdii, a large ungulate species from the Neotropics, in relation to moon phases in two sites with different degree of human perturbation: the Calakmul Biosphere Reserve (CBR) and the Nuevo Becal (NB) community. We monitored twenty waterbodies in each site for 18 months using camera traps. The photographic capture rate (CR) and the corresponding moon phases for both sites were recorded. The CR of T. bairdii was 0.054 in NB and 0.029 in CBR. T. bairdii was more active at night and dawn-twilight periods. In general, T. bairdii showed major activity during the dark moon phases but the differences with the light phases were not statistically significant. However, we found a trend of tapirs to be more active in dark nights and in the darkest hours in NB than CBR. The apparent preferences for dark nights in NB could be caused by the perturbation caused by human activities at site, which may have influenced the behavior of the tapir that avoid moving out in periods of abundant light in disturbed sites. More research is needed to confirm this finding.

THE EFFECT OF PHYTOHORMONES AND LIGHT ON THE GERMINATION OF APPLE POLLEN WITH REDUCED VIABILITY

Background. Studying the effect of phytohormones and light on the germination of apple pollen with reduced viability on an artificial nutrient medium is of importance, because it may facilitate an increase in the germination percentage among plant samples promising for breeding after their long-term preservation under low temperatures.Materials and methods. Pollen viability of the apple-tree cultivar ‘Krasnolistnaya’ was measured by germinating it on an artificial nutrient medium containing 10% sucrose solution and 0.8% agar. Drops of a distilled water suspension of pollen with added phytohormones were applied to the surface of the nutrient medium. Pollen was germinated in the dark (24 hours in a thermostat at 21°C) and under light (in an artificial light chamber at 21°C with a photoperiod of 16 hours of light / 8 hours of darkness). Results. Pollen of cv. ‘Krasnolistnaya’ with reduced viability most effectively germinated with the use of gibberellin at a concentration of 1 mg/l and 10 mg/l: the germination percentage was 22.3±0.8% and 21.8±1.3% respectively (сf. 10.9±1.5% in the reference). The most effective combination of phytohormones was gibberellin 10 mg/l + kinetin 10 mg/l – the percentage of germination was 22.8±6.3%; kinetin 1 mg/l + indolylbutyric acid 1 mg/l – the percentage of germination was 17.5±5.9% vs. 10.9±1.5% in the reference.Conclusion. Phytohormones were observed to have a significant effect on the germination of apple pollen with reduced viability. Effective concentrations and combinations of phytohormones that promote the germination of pollen with reduced viability have been identified. Light does not affect the germination of pollen with reduced viability.

The problem of fire fighting during the hours of darkness

The article presents the results of the first stage of investigation, aimed at improving the efficiency of the system for forest protection from fire by improving the organization and works to extinguish forest fires due to the optimal use of the dark conditions, increasing the safety of workers of forest fire groups in difficult conditions. The possibility of increasing the impact degree on the border of an existing forest fire with available forces and tools on the first day is equivalent to gaining an increase in the amount of labor hours spent within one operational period. It is comparable to the positive effect of using additional forces for a short period of time. The article presents the results of the first stage of the study. The analysis results of the state in the practice of extinguishing forest fires t dark conditions are presented. In analysis, the attention is focused on the peculiarities of the extinguishing forest fires in difficult conditions, taking into account the influence of the main regulatory factors such as limited visibility, terrain, types of plantings and ground cover, weather conditions, tools and fire extinguishing equipment used, tactical techniques and fire extinguishing methods, equipment firefighting units by individual and group protection tools, application of standard procedures for controlling forces and equipment in a fire, presence of hazardous working conditions, compliance the regulations of the existing law. In the course of the analysis, domestic and foreign experience of extinguishing forest fires at dark conditions was considered. A field research program for the next phase has been organized.

Remote Sensing Imagery Improves Safety and Logistics of Arctic Operations

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper OTC 29115, “Application of Remote Sensing Imagery and Ancillary Products to Improve Safety and Logistical Efficiency of Arctic Operations,” by Tiffany Carey and Khalid Soofi, SPE, ConocoPhillips, prepared for the 2018 Arctic Technology Conference, Houston, 5–7. Copyright 2018 Offshore Technology Conference. Reproduced by permission. Many forms of remote sensing imagery can be used, along with datasets and the resultant products, to improve the efficiency and safety of upstream oil and gas operations on the North Slope of Alaska, which is characterized by limited road access, seasonally restrictive operations, and stringent environmental regulations. This paper discusses how optical satellite and aerial imagery, high-resolution light detection and ranging (LiDAR) for digital elevation and digital surface models, and synthetic aperture radar (SAR) have enabled one operator to undertake detailed logistical planning of field operations in the Alaskan Arctic by gaining a better understanding of the landscape, environment, and overall regional investigations. Introduction Significant growth in remote sensing systems and techniques has enabled advanced desktop studies and technical investigations, particularly in remote areas such as the Alaskan Arctic. Arctic regions are, by nature, highly inaccessible and consequently problematic to investigate for the purposes of logistical planning of field operations. The North Slope, covering approximately 100,000 acres of northern Alaska and bounded on the north coast by the Chukchi and Beaufort Seas, exemplifies these qualities. Less than 1% of this region is covered by gravel road systems. North Slope oil fields are concentrated in a very small portion of this area. Extensive regulation governs both ground and air access to protect and preserve the environment and wildlife in the region, and to respect the cultural resources and Inupiat lifestyle of the 10,000 residents spread among eight villages. Meandering and braided fluvial systems and stationary waterbodies vary seasonally in size, volume, and state. The environment has been sculpted by significant fluvial systems that drain from the Brooks Range into the Beaufort Sea. High-energy river drainages with steep-cut banks and expansive gravel bars leave abandoned channels and oxbows across the dynamic landscape. The tundra is marked by numerous waterbodies with a wide range of depths. Small ponds and lakes often have the most significant depth profiles. Light or deep snow levels; thin, thick, or grounded ice conditions on lakes; and overflow conditions on the rivers can plague preparation and execution of North Slope winter operations. Because of the substantial portion of the North Slope that is inaccessible by road, winter tundra access for exploration operations is the only option for most of the region. North Slope winter-season length is established on the ability of the tundra to reach predetermined frost depths and snow thickness, which must be achieved to commence work. The formal annual opening and closing of the tundra is governed by federal and state agencies. All off-road winter operations must adhere to these regulations. The winter season has varied from 97 to 145 total days during the past 15 years. On top of the short winter work season, the Arctic is also known for its winter darkness. More than 50 days of the winter season have no daylight, which dramatically affects health, safety, and environment (HSE) regulations for working in the North. However, given the 24 hours of darkness, International Association of Oil and Gas Producers standards and operator HSE regulations allow for 24-hour operations.

Evidence Against the Defensive Activation Theory of REM Sleep

David Eagleman and DA Vaughn have recently posited a very interesting new hypothesis of the 1​ function of REM sleep and dreaming​ . They posit that REM sleep is there to keep the visual cortex active during the dark hours of night to prevent the neuroplasticity that happens during darkness, making the visual cortex responsive to non-visual stimuli. Here, we make predictions to test the theory and show that the evidence examined does not lend support to the aforementioned theory. In particular, the fact that blind species show REM sleep comparable to that of their vident counterparts suggests the role of REM sleep is not specific to vision.