Conditions Of Total Darkness Research Articles

Phosphor-Enhanced, Visible-Light-Storing g-C3N4/Ag3PO4/SrAl2O4:Eu2+,Dy3+ Photocatalyst Immobilized on Fractal 3D-Printed Supports.

The combination of a phosphor with semiconductor photocatalysts can provide photoactivity in the dark. Indeed, the phosphor acts as a "light battery", harvesting photons during irradiation and later re-emitting light that can be used by the catalytic phase when in conditions of total darkness. This allows for continued activity of the composite catalyst, even in conditions of unstable light stimulation. In this study, we assess the use of a heterojunction, namely graphitic-C3N4/Ag3PO4, that enables efficient photoactivity specifically under visible light stimulation, in combination with a phosphor that exhibits green-blue phosphorescence (510 nm), that is SrAl2O4:Eu2+,Dy3+. Our findings showed that this combination was particularly interesting, noticeably displaying significant photoactivity in darkness, after short periods of activation by visible light. After finding the right combination and optimal ratios for maximum efficiency, the resulting catalyst composite was immobilized on resin supports with a fractal surface, printed by LCD-SLA 3D printing. The immobilization was effectuated via an aqueous-phase plasma-aided grafting (APPAG) process, using cold plasma discharge (CPD) and using vinylphosphonic acid (VPA) as a coupling agent. Whereas the colloidal photocatalyst displayed a serious problem of partial physical separation between the catalytic phase, g-C3N4/Ag3PO4, and the phosphor, the immobilization of the composite catalyst on polymer supports allowed solving this issue. Photodegradation assessments confirmed that the hybrid supported phosphor-enhanced catalyst was active, notably in dark conditions, as well as fairly photostable. This study offers new prospects for the fabrication of polymer-based panels for water purification, with round-the-clock activity and that are, in addition, extremely easy to recover and reuse, by comparison with colloidal catalysts.

Melatonin rhythm and other outputs of the master circadian clock in the desert goat (Capra hircus) are entrained by daily cycles of ambient temperature.

In desert areas, mammals such as camel and goat are exposed to harsh environmental conditions. The ambient temperature (Ta) cycles have been shown to entrain the circadian clock in the camel. In the present work, we assumed that, in the goat living in a desert biotope, Ta cycles would have the same synchronizing effect on the central clock. Therefore, the effects of Ta cycles on body temperature (Tb), locomotor activity (LA) and melatonin (Mel) rhythms as outputs of the master circadian clock have been studied. The study was performed on bucks kept first under constant conditions of total darkness (DD) and constant Ta, then maintained under DD conditions but exposed to Ta cycles with heat period during subjective day and cold period during subjective night. Finally, the Ta cycles were reversed with highest temperatures during the subjective night and the lowest temperatures during the subjective day. Under constant conditions, the circadian rhythms of Tb and LA were free running with an endogenous period of 25.3 and 25.0hours, respectively. Ta cycles entrained the rhythms of Tb and LA to a period of exactly 24.0hours; while when reversed, the Ta cycles led to an inversion of Tb and LA rhythms. Similarly, Ta cycles were also able to entrain Mel rhythm, by adjusting its secretion to the cooling phase before and after Ta cycles inversion. All together, these results show that the Ta cycles entrain the master circadian clock in the goat.

Nocturnal oviposition of the forensic scuttle fly, Megaselia scalaris (Loew) (Diptera: Phoridae) indoors

In forensic entomology, nocturnal oviposition of flies could reduce discrepancy of minimum post-mortem interval (PMImin) estimation which is due to assumption that oviposition only occurs during day time hours. Previous records indicate that some forensic species of Calliphoridae and Sarcophagidae displayed nocturnal oviposition and larviposition but such occurrences can be inconsistent. Apart from blow flies and flesh flies, the scuttle flies (Diptera: Phoridae) are known to be forensically important indoors and they exhibit diurnal and nocturnal behaviour. To investigate if oviposition by scuttle flies occurs during night or day time hours, baited scuttle fly traps consisting decomposed cow’s liver were placed inside the Forensic Entomology Laboratory, Faculty of Health Sciences, Universiti Kebangsaan Malaysia on diurnal and nocturnal intervals. The traps were divided into two groups, i.e. light-exposed and total dark conditions. It was discovered that all specimens collected were Megaselia scalaris (Loew) and they were active and performed oviposition during day and night times. Light exposure did not affect oviposition activity during diurnal and nocturnal periods. Therefore, it is recommended that nocturnal oviposition must be taken into consideration when using this fly as reference for PMImin estimation.

Semiconductor Laser Night Vision Image of Vehicle Recognition Based on Image Processing

The semiconductor laser night imaging system introduced in this paper is an active imaging system. The system using laser as light source,can get the night scene in total darkness conditions at night. So this system has been widely used in the field of public security and vehicle recognition.This system is composed of semiconductor laser diode array, laser transmitting and receiving optical system, camera receiver and DSP system and so on. The main character of this system is the technology of non-scanning laser imaging to obtain laser range images, and then the images are under the treatments of real-time collection, storing, superpose filtering, and characteristics extraction. With the program of centroid coordinate of the target, the optical axis of the optical system will be in coincidence and the action order will be formed.

Induction of anthocyanin pigments in callus cultures of Rosa hybrida L. in response to sucrose and ammonical nitrogen levels

The influence of varied concentrations of sucrose and ammonical (NH4+) nitrogen on in vitro induction and expression of anthocyanin pigments from Rosa hybrida cv. ‘Pusa Ajay’ was investigated. Of two explants (petal and leaf discs) selected and cultured under two different conditions (light and dark), leaf discs were found to be most suitable for callus initiation. Profuse and early callus induction was observed when leaf discs of rose were cultured under total dark conditions on solid Murashige and Skoog (MS) medium supplemented with 4.0 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D). Early pigment initiation, enhancement and maximum anthocyanin production from calluses were recorded when leaf discs were cultured on Euphorbia millii (EM) medium supplemented with 7% sucrose compared with calluses cultured at 4% sucrose concentration under 16/8 h (light/dark) photoperiod regime. Reducing the concentration of NH4+ nitrogen in the solid MS medium led to slight improvement in anthocyanin production in rose leaf calluses.

Are There Adaptation Levels to Cave Life in Crayfish?

Abstract The stygobitic crayfish Procambarus cavernicola and Procambarus oaxacae reddelli and the epigeal crayfish Procambarus olmecorum were maintained in laboratory conditions in order to compare their oxygen consumption rates by measuring the decreasing oxygen concentration. These closely related species belong to the same subgenus and live in nearby caves and surface streams located in the same karstic region found in northern Oaxaca, Mexico. The consumption rates were monitored in laboratory conditions during fifteen hours in water maintained at 20°C without food. Significant differences among the species were found. Although these species live in similar conditions of total darkness during their life cycles, P. cavernicola had the higher oxygen consumption rate; this is a result of being slightly conditioned to oxygen partial pressures of the experimental bottle. Procambarus oaxacae reddelli showed a lower oxygen consumption rate strongly correlated to the oxygen partial pressure of the water. The e...

REGULATION OF PHOSPHATASE ACTIVITY IN CHROOCOCCID- IOPSIS ISOLATES FROM TWO DIVERSE HABITATS: EFFECT OF LIGHT, PH AND TEMPERATURE

Phosphomonoeaterase (PMEase) and phosphodiesterase (PDEase) activity was studied in the cyanobacterial cultures of Chroococcidiopsis isolated from two diverse cryptoendolithic habitats of Antarctic and Arizona. Because this organism is found within the rocks it appears that phosphorus metab- olism by alkaline phosphatase activity is a key factor to sustain growth of these organisms in that state, there being no other source of external P except in bound form in the rocks. The main findings in this paper show that specific pH and temperature regulate the PMEase and PDEase activities studied with different substrates in isolated of Chroococcidiopsis 1 and 2 although values were vastly different. The pH and tem- perature optima for phosphatase activity (PMEase and PDEase) of Chroococcidiopsis 1 and 2 were 9.5, 20 °C and 8.5, 40 °C respectively. It needs mentioning here that although the pH optimum for the enzyme activities in the Antarctic rock samples was the same i.e. 9.5 there was a striking difference in the tem- perature optimum in which maximum activity of both enzymes were recorded at 5 °C. A very crucial role of light and dark conditions were important for the enzyme activity and differed to a significant extent when compared with naturally occurring organisms in the Antarctic rocks. Low light fluxes of about 8 µmol photon m -2 s -1 showed higher PMEase and PDEase activity then total dark conditions in the Chroococcidiopsis -1 culture. However under natural conditions when this organism is found within the rocks 8-µmol photon m -2 s -1 was found to be inhibitory and dark conditions gave higher PMEase and PDEase activity. Arizona rock samples containing Chroococcidiopsis -2 however did not show dark stim- ulation. Increase in light intensity from 8 µmol photon m -2 s -1 to 60 µmol photon m -2 s -1 maintained in the cul- ture room increased the PMEase and PDEase activity of both cultures. The unique light and temperature responses for PMEase and PDEase activities in Chroococcidiopsis-1 found within the Antarctic rocks are unique. It points to some change in the cells probably by producing some cryoprotectant which protects the enzymes from becoming non functional at low temperatures. It also indicates that exposure to light fluxes as low as 8 µmol photon m -2 s

Habitat‐adapted communication in Trite planiceps, a New Zealand jumping spider (Araneae, Salticidae)

The natural history and intraspecific interactions of Trite planiceps, a common New Zealand jumping spider (Salticidae), are described for the first time and discussed in relation to this salticid's unusual microhabitat ‐ the rolled‐up leaves of New Zealand flax (Phormium tenax) and similar plants. In many respects, T. planiceps’ display and mating behaviour resembles other salticids. Males have conditional courtship and mating tactics, and the tactics used depend on the female's maturity and location. If in the light, the male uses vision‐based courtship and mates in the open; if at a nest (inside a rolled‐up leaf), the male uses vibratory courtship and mates inside the rolled‐up leaf; if the female is immature but within c. 10 days of maturing, the male cohabits until the female matures and then mates inside the rolled‐up leaf. Regardless of which mating tactic is used, after males mount females there is a phase during which the pair are in physical contact and communicate using tactile signals ('post‐mount courtship'). Other sex and age classes of T. planiceps also communicate using visual displays when in light, away from rolled‐up leaves, and also sometimes employ tactile signals when at nests or during escalated contests in the light. In addition to these typical salticid characteristics, T. planiceps has some atypical display behaviours that appear to be adapted for communicating in its unusual habitat. Even when no conspecific has been encountered, T. planiceps males sometimes display when approaching openings of rolled‐up leaves occupied by conspecific females. These displays closely resemble visual displays used while facing a conspecific in the light. Later, while entering the cavites within rolled‐up leaves and while moving about inside simulated rolled‐up leaves (glass tubes kept away from visible light and observed using infra‐red video), males and females use vibratory displays, tapping the leaf surface with Legs I and vibrating their abdomens, even when no conspecific has been encountered. Finally, when spiders interact within simulated rolled‐up leaves, they appear to communicate using both tactile signals and vibratory signals that are transmitted through nests or leaf surfaces. Many other salticids use nests as a medium for transmission of vibratory signals. However, T. planiceps’ use of the leaves forming its nesting microhabitat for this function is unusual. This is the first study in which infra‐red video has been used to observe interactions between salticids under conditions of total darkness for the spider, and also the first report of a salticid possessing a display repertoire for use in darkness but away from nests. We emphasise adaptation for typical habitat as a partial explanation for species differences in salticid communication systems.

A novel circadianly expressed Drosophila melanogaster gene dependent on the period gene for its rhythmic expression.

The Drosophila melanogaster period (per) gene is required for expression of endogenous circadian rhythms of locomotion and eclosion. per mRNA is expressed with a circadian rhythm that is dependent on Per protein; this feedback loop has been proposed to be essential to the central circadian pacemaker. This model would suggest the Per protein also controls the circadian expression of other genetic loci to generate circadian behavior and physiology. In this paper we describe Dreg-5, a gene whose mRNA is expressed in fly heads with a circadian rhythm nearly identical to that of the per gene. Dreg-5 mRNA continues to cycle in phase with that of per mRNA in conditions of total darkness and also when the daily feeding time is altered. Like per mRNA, Dreg-5 mRNA is not expressed rhythmically in per null mutant flies. Dreg-5 encodes a novel 298 residue protein and Dreg-5 protein isoforms also oscillate in abundance with a circadian rhythm. The phase of Dreg-5 protein oscillation, however, is different from that of Per protein expression, suggesting that Dreg-5 and per have common translational but different post-translational control mechanisms. These results demonstrate that the per gene is capable of modulating the rhythmic expression of other genes; this activity may form the basis of the output of circadian rhythmicity in Drosophila.

Use of the lateral line for feeding in the torrentfish (Cheimarrichthys fosteri)

Torrent fish feeding on natural prey in an artificial stream were studied under conditions of total darkness. The distance at which prey could be detected increased with size of prey, and decreased...

褐藻ジョロモクとアカモク幼はいの低照度下の生長

The effect of low light intensity on thallus and rhizoid growth of the germlings of Myagropsis myagroides and Sargassum horneri was studied. The germlings were cultured for 8 weeks at 20°C under two different light intensities with 12L/12D and total darkness. In both species, the thalli and rhizoids of the germlings grew well at 2000-2800lx. In S. horneri, furthermore, under this condition many adventitious branches were formed from rhizoids of individuals. In M. myagroides and S. horneri, the thalli and rhizoids of the germlings grew very slowly under the conditions of total darkness and 200-300lx. In both species, however, after 8 weeks under these conditions no individuals detached from the substratum or died. Moreover, the germlings of these two species had been cultured for 2, 4, and 6 weeks under these conditions, after which they were transferred to the condition of 2000-2800lx and cultured for 2 weeks. These germlings showed rapid growth after the transfer. In both species, the germlings which were cultured in this study were attached to the substratum by rhizoids. Staining with alcian blue revealed that an adhesive substance surrounded the rhizoids.

Transcranial Doppler ultrasonographic assessment of intermittent light stimulation at different frequencies.

Seven normal adult volunteers underwent intermittent photic stimulation at frequencies of 5-60 Hz while their posterior cerebral arteries were monitored using transcranial Doppler ultrasound. Baseline measurements were obtained under conditions of total darkness, and sampling was also done during continuous illumination. Overall variation in mean flow velocity between complete darkness and continuous illumination was 9.8%, but the maximal change (expressed as percentage deviation from baseline) occurred consistently when stimulation was undertaken at frequencies of 10 (21%) and 20 (19%) Hz (p = 0.05). Frequencies higher than 20 Hz resulted in mean flow velocity variations that were not significantly different from that found during continuous illumination. The optimal frequency of intermittent visual stimulation required to induce measurable changes in posterior cerebral artery Doppler characteristics appears to be in the range 10-20 Hz.

DRL responding under conditions of total darkness

The effects of total darkness on DRL schedule control were studied with pigeons under two lighting conditions. Increased DRL schedule control is indicated by decreased response and response/reinforcer rates and by increased reinforcer rates. Four pigeons with prior training on DRL schedules were conditioned to keypeck in total darkness. There were five blocks of sessions. In Blocks 1–4, subjects were trained on four alternating blocks of sessions under dark and light conditions (ABAB design). Block 5 consisted of four alternating sessions of dark and light conditions (ABAB design). Comparison of the dark with the light condition showed 3 subjects with decreased response and response/reinforcer rates and increased reinforcer rates in the dark condition. The results indicate increased control with DRL schedules under conditions of total darkness and are in agreement with Robinson and Shelley’s (1974) study in which increased control was demonstrated for FI, VI, FR, and VR schedules.

Modulation of reproductive output in Drosophila by spectral properties of ambient light

The net reproductive output was determined for two strains of Drosophila melanogaster, wild-type (+) and white-eyed (w), under conditions of varied wavelength and intensity of illumination. The reproductive output of wild-type flies raised under blue light (max. 470 nm) was significantly lower (p < 0.01) than that of organisms grown under red (max. 630 and 660 nm) or green(max. 530 nm) illumination, or under conditions of total darkness. In contrast, blue light did not depress the reproductive output of white-eyed flies. The differential reproductive response of the two strains, then, appears to be related to genetically determined properties of the eye. Changes in the radiant fluence rate over a 10-fold range were not found to significantly modify reproductive output of wild-type flies, and if flies were illuminated with red, green, or blue light at identical fluence rates, those under blue, again, had a significantly lower (p < 0.01) reproductive output than the other two. The data suggest that the emission spectrum, not the radiant light intensity, significantly affects the number of offspring produced per parent.

VERGENCE EYE‐MOVEMENT RESPONSES TO WHOLE‐BODY LINEAR ACCELERATION STIMULI IN MAN*

Eight human subjects were exposed to periodic linear acceleration stimuli of +/- 1.0 ms-2 at 0.2 Hz and +/- 2.5 ms-2 at 0.3, 0.45 and 0.67 Hz, whilst lying in the supine position on a large-stroke vertical vibration platform. Eye movements were recorded by an infrared corneal reflection technique. In conditions of total darkness, with no visual stimulation, all subjects exhibited eye-movement responses composed of both conjugate and vergence components. Subsequent computer analysis of the vergence eye-movement responses showed that they were periodic and related to subject displacement. In a second experimental condition, a platen-fixed LED matrix fixation target was illuminated 0.91 m vertically above the subject. It was found that fixation upon this target did not abolish the vergence eye-movement response, although it was suppressed by approximately 50%.

Activity and metabolism of 9‐substituted cytokinins during lettuce seed germination

The activities of N6‐benzyladenine (BA) and its 9‐substituted methyl, methoxymethyl, tetrahydropyranyl, cyclopentyl, and cyclohexyl analogs were determined for the promotion of lettuce seed (Lactuca sativa L. cv. Grand Rapids) germination. Cytokinin concentrations used were 10−4, 10−5, 10−6 and 10−7M. All seeds were incubated under total dark conditions at 28 ± 1°C. After 48 h the percentage of germination was recorded. A comparison of means based on Duncan's Multiple Range Test allowed for a ranking of cytokinin activities for the promotion of lettuce seed germination. The activities were: BA = 9‐tetrahydropyranyl BA > 9‐methyl BA > 9‐methoxymethyl BA > 9‐cyclopentyl BA > 9‐cyclohexyl BA. The results were significant at the 95% confidence level as determined by analysis of variance. In order to study the metabolism of a cytokinin, lettuce seeds were incubated with 9‐methyl‐BA‐methylene‐14C. The labeled cytokinin was prepared by refluxing benzylamine hydrochloride (methylene‐14C) with an equal molar ratio of 6‐chloro‐9‐methylpurine. Final cytokinin concentration was 10−5M. Incubation periods were 2, 4, 8, 12, 16 and 20 h at 28 ± 1°C under total dark conditions. At the end of the various time periods the seeds were extracted with 70 percent methanol. The resulting extracts were purified and radioactive metabolites identified by solvent fractionation, Sephadex LH‐20 column chromatography, and paper chromatography. Co‐chromatography with authentic standards in the appropriate solvent system revealed that the metabolites were 9‐methyl BA, N6‐benzyladenosine‐5′‐monophosphate, and N6‐benzyladenosine. The results lend support to the theory that the cytokinin ribonucleotide serves as a storage form which is converted to the active ribonucleoside as needed during lettuce seed germination.

Flower Initiation of Brassica Species under Total Darkness1

Abstract The in vitro flowering responses in conditions of total darkness were studied in several cultivars of diploid and tetraploid Brassica species. Diploid species with the A genome tended to form flowers about equally at high or low temperature, the single B genome species formed some flowers only at high temperature and those with C genome not at all. Similarly, allotetraploid species with the AC genomes tended to flower as did certain of those with the BC and AB genomes but to a considerably lesser extent. Leaf formation was correlated with flowering.

Effects of seasonal acclimation on the preferred body temperature of Thamnophis elegans vagrans

1. 1.|An Experimental group of wandering garter snakes from a montane habitat was maintained over winter under laboratory conditions of total darkness and 4°C. 2. 2.|Their mean preferred body temperature (30.7°C) on a constant temperature thermal gradient was significantly higher than the preferred body temperature (24.5°C) of another group of wandering garter snakes collected and tested in late summer.

Suppression of visual phosphenes during saccadic eye movements

A loss of visual sensitivity is shown to accompany a saccadic eye movement even under conditions of total darkness. Optical factors are eliminated by the use of electrically produced phosphenes, rather than flashes of light, to test the changes in visual threshold. Separate experiments matching the brightness of electrical phosphenes to real lights allow the threshold changes to be expressed in terms of real light. The results point to the conclusion that a substantial portion of saccadic suppression is neural, rather than optical in its origin. The time course of the suppression is consistent with electrophysiological studies in cat and monkey in which inhibition of nerve impulses occurs over a period that includes, but is considerably longer than the duration of the eye movement. No correlation has yet been shown, however, between the occurrence of saccadic suppression and identifiable features of the human visually evoked occipital responses. Saccades of a given amplitude are found to be slower in total darkness.

Light effects on fruiting in Panus tigrinus var. tigrinus

In the Basidiomycete Panus tigrinus var. tigrinus, continuous fluorescent light results in increased production of numbers of abnormal fruiting bodies. With progressively longer dark periods before continuous light there is a decrease of abnormal fruits. The total number of fruiting bodies remains relatively constant regardless of light/dark treatment. However, no fruiting occurs under conditions of total darkness. Differentiation between normal and abnormal fruiting bodies begins after light exposure, and the normal primordia develop a dark pigmentation near the tip. Such pigmentation is believed to be significant in inducing normal basidiocarps.