bluuebunny/crossref_metadata_2025 huggingface dataset:
Probabilistic assessment of contamination using the two-phase flow model
Authors: Chen Guan-Zhi , Hsu Kuo-Chin , Lee Cheng-Haw
Published: April 2009

A physically motivated model is indispensable for a successful analysis of the impact of leaching from nuclear waste storage sites on the environment and public health. While most analyses use the single-phase flow model for modelling unsaturated flow and solute transport, the two-phase flow model considering the resistance of gas to water flow is a more realistic one. The effect of the two-phase flow model on the water content is theoretically investigated first in this study. Then, by combining a geostatistical generator using the turning bands method and a multi-phase transport code TOUGH2, an automatic process is used for Monte Carlo simulation of the solute transport. This stochastic approach is applied to a potentially polluted site by low-level nuclear waste in Taiwan. In the simulation, the saturated hydraulic conductivity is treated as the random variable. The stochastic approach provides a probabilistic assessment of contamination. The results show that even though water content from the two-phase flow model is only 1.5% less than the one from the single-phase flow model, the two-phase flow causes a slower movement but a wider lateral spreading of the plume in the unsaturated zone. The stochastic approach provides useful probability information which is not available from the deterministic approach. The probability assessment of groundwater contamination provides the basis for more informed waste management, better environmental assessment and improved evaluation of impact on public health.
Evaluation of pre-treatment methods for landfill disposal of residues from municipal solid waste incineration
Authors: Kim Sang-Yul , Matsuto Toshihiko , Tanaka Nobutoshi
Published: April 2009

This study presents results concerning leaching of Pb, Cd, Ca, and Cl with reference to one individual batch of bottom ash and fly ash (5:1) resulting from a municipal solid waste incinerator (MSWI) in Japan. This ash mixture was stabilised by the following pre-treatments: water washing, carbonation, and phosphate stabilisation. Once the optimum processing condition for each pre-treatment was determined, the performances were evaluated using both pH-stat leaching (pH 6, 9, 12) and availability tests. These performance tests were carried out with only fly ash without considering the mixture of MSWI residues, in order to accurately determine leaching differences among the pre-treatments.

Water washing effectively removed the major elements from MSWI residues and also reduced the leachability of trace metals, such as Pb and Cd. A washing time of 15 minutes with a liquid/solid ratio of 5 was reasonably effective. Carbonation had a significant effect on leachability in alkaline ranges (pH 9 and 12), when the reaction occurred only on the surface of MSWI residues, moreover a moisture content of 10-16.7% was proved suitable for carbonation. On the other hand, phosphate stabilisation, even with small amounts of phosphate (0.16 mol-PO43- kg-1), was very effective in reducing the leach-ability of heavy metals.
Use of lignite fly ash as an additive in alkaline stabilisation and pasteurisation of wastewater sludge
Authors: Kocaer Fatma Olcay , Alkan Ufuk , Baskaya Hüseyin Savas
Published: April 2009

In this study, the possibility of using lignite fly ash in low doses for reducing the pathogen levels in wastewater sludge was investigated. The results showed that using fly ash alone in doses of 40%, 80% and 120% (on a dry weight basis), did not produce an alkaline environment for an efficient removal of pathogens. However, using fly ash in conjunction with the minimum amount of quicklime may act as an effective way of fecal coliform removal in both alkaline stabilisation and pasteurisation processes. It was shown that using fly ash in doses of 80% and 120% in alkaline stabilisation and pasteurisation processes prevented the pH decays and regrowth of pathogens during 60 days of storage period. The results of the study confirmed that alkaline pasteurisation process produces a product which is more resistant to pH decays and regrowth of fecal coliforms compared to that of alkaline stabilisation. Consequently, the overall results of this study indicated that the minimum lime and fly ash dosages required to generate a Class B biosolid were 10-15% and 80%, respectively. On the other hand, heating sludge to 50°C prior to the addition of 10-15% quicklime and 80% fly ash followed by further heating to 70°C and then sustaining at this temperature for 30 minutes were sufficient to generate a Class A biosolid.
Spent potlining utilisation possibilities
Authors: Mikša Dragan , Homšak Marko , Samec Niko
Published: April 2009

As the world’s capacity for aluminium production increases, the amount of waste connected with this industry is also increasing. Spent potlining (SPL) from aluminium reduction cell cathodes presents a major environmental concern in the primary aluminium industry. It is concluded, after laboratory tests, that leachable cyanide and fluoride compounds present the major problem in SPL disposal. The behaviour of cyanide and fluoride under high temperature treatment has been investigated.

On the basis of this laboratory investigation, the possibilities for SPL utilisation in red brick manufacturing, cement industry and thermal power stations were evaluated. SPL refractory material is already re-used in red brick manufacturing. In the cement industry, a pilot test on the utilisation of 25 t SPL carbon waste mixed with green petrol coke gave positive results. Additionally a fluoride emission forecast for a thermal power station utilising carbon waste SPL mixed with coal was elaborated.
Report: Pipeline transport of solid waste in the Grand Holy Mosque in Makkah
Authors: Al-Ghamdi Abdullah Saeed , Abu-Rizaiza Asad Seraj
Published: April 2009

The Grand Holy Mosque, located in the Holy City of Makkah in Saudi Arabia, attracts millions of Muslim visitors from all over the world, especially during the pilgrimage season. The daily amount of refuse generated in the Grand Holy Mosque and surrounding plazas reached a maximum value of 192.8 tons/day in 1998. Collection and transport of the solid waste generated during the peak times present a challenge to the Makkan authorities. The congested streets and high population density in the Holy Mosque and its surrounding plazas make the traditional methods of collecting and transporting solid waste impractical.

This paper presents an alternative system for the collection and transport of solid waste generated in and around the Grand Holy Mosque in Makkah. The proposed system is based on a pneumatic transport technique, by which the waste is collected and transported in underground pipelines. A conceptual layout of the proposed system in the Mosque area is presented, and the merits of the suggested system are discussed.
Hydraulic activity of cement mixed with slag from vitrified solid waste incinerator fly ash
Authors: Lin Kae-Long , Wang Kuen-Sheng , Tzeng Bor-Yu , Lin Chung-Yei
Published: April 2009

This study investigates the effects of the slag composition on the hydraulic activity in slag blended cement pastes that incorporate synthetic slag prepared by melting CaO-modified municipal solid waste incinerator fly ash. Two types of composition-modified slag were prepared for this study. First, fly ash was mixed with the modifier (CaO) at 5% and 15% (by weight) respectively, resulting in two fly ash mixtures. These mixtures were then melted at 1400°C for 30 minutes and milled to produce two types of slag with different modifier contents, designated as C1-slag and C2-slag. These synthetic slags were blended with ordinary Portland cement at various weight ratios ranging from 10% to 40%. The synthetic slags presented sufficient hydraulic activity, and the heavy metal leaching concentrations all met the EPA's regulatory thresholds. The pore size distribution was determined by mercury intrusion porosimetry, and the results correlated with the compressive strength. The results also indicate that the incorporation of the 10% C1-slag tended to enhance the hydration degree of slag blended cement pastes during the early ages (3-28 days). However, at later ages, no significant difference in hydration degree was observed between ordinary Portland cement pastes and 10% C1-slag blended cement pastes. In the 10% C2-slag case, the trend was similar, but with a more limited enhancement during the early ages (3-28 days). Thus vitrified waste incinerator fly ash is a technically useful additive to cement, reducing the disposal needs for the toxic fly ash.
Long-term assessment of waste management options - a new, integrated and goal-oriented approach
Authors: DöBerl G. , Huber R. , Brunner P. H. , Eder M. , Pierrard R. , Schönbäck W. , Frühwirth W. , Hutterer H.
Published: April 2009

Selected waste management scenarios were evaluated with regard to the goals of the Austrian Waste Management Act, taking into account long-term environmental protection and resource conservation as well as costs. Municipal solid waste (MSW) and sewage sludge have been chosen as the system inputs. The scenarios were compared to the status-quo scenario by combining Material Flow Analysis (MFA) and economic evaluation methods. Both, welfare-oriented Cost-Benefit Analysis (CBA) and Modified Cost-Effectiveness Analysis (MCEA) were applied for this assessment. Unlike CBA, MCEA takes into consideration long-term impacts of landfilled material in non-monetary terms. The results of the CBA correspond to those of the MCEA. Both evaluation methods confirm: If long-term effects are taken into account with the same weight irrespective of when they occur, the Austrian goals of waste management are reached more efficiently by thermal waste treatment scenarios than by mechanical-biological treatment scenarios or by landfilling without pre-treatment.
Availability and quality of solid waste and wastewater in Southern Thailand and its potential use as fertiliser
Authors: Schouw Nanette Levanius , Tjell Jens Christian , Mosbæk Hans , Danteravanich Somtip
Published: April 2009

Recycling nutrients to agriculture with waste in Southern Thailand has been assessed in three model-areas: Kuan Lang, Prik and Phattalung. Samples of biodegradable solid waste and gray wastewater were collected and characteris ed physically and chemically.

At present nutrients in the biodegradable solid waste and wastewater are lost, but especially kitchen waste and grey household wastewater constitute a large fertiliser potential. The average daily per capita generation rate of household kitchen waste is 228 g wet matter, 0.65 gN, 0.16 gP, 0.34 gK, 0.05 gS, 0.39 gCa, 0.06 gMg, 6.9 mgZn, 0.29 mgCu, 0.05 mgNi, 0.02 mgPb, 0.09 mgCd and 0.006 mgHg. The average daily per capita generation rate of grey household wastewater is 102 L, 2.4 gN, 2.4 gP, 4.2 gK, 2.0 gS, 2.2 gCa, 0.82 gMg, 42 mgZn, 0.91 mgCu, 1.6 mgNi, 0.46 mgPb, 0.20 mgCd and < 0.06 mgHg. The waste products generally contain higher amounts of K, Ca, Mg, Zn, Cu and Pb (relative to phosphorous) than conventional chemical fertiliser, while N, S, Ni, Hg and Cd is at the same level.
Removal of hydrophobic organic pollutants by coagulation-precipitation process with dissolved humic matter
Authors: Kim Yongjin , Osako Masahiro , Lee Donghoon
Published: April 2009

The removal of hydrophobic organic pollutants (HOPs) from water with precipitating dissolved humic matter (DHM) was found to depend on the physical and chemical properties of the HOPs themselves, and could be estimated theoretically. The removal efficiency of HOPs was decreased at high pH and with increasing ionic strength; in particular, when ionic strength increased, the decrease was small. In deionised water, the removal efficiencies of pyrene, fluoranthene, anthracene and phenanthrene were about 75%, 57%, 40% and 30% respectively in the DHM range used, and increased clearly with increasing concentration of DHM. The difference of removal efficiency resulted from the physical and chemical characteristics of the HOPs such as partition coefficient to DHM (KOC), whose order is pyrene > fluoranthene > anthracene > phenanthrene. Because of the large partition coefficients of dioxins to DHM, removal efficiencies of 90 to 99.9% could be obtained with only a few mg l-1 of organic carbon (OC) in DHM and 99 to 99.99% with over ten mg-OC l-1 in DHM.
Characterisation and treatment of roads covered with zinc ashes, muffle furnace fragments and lead slags from former non-ferrous metal industries in Belgium
Authors: Vandecasteele C. , Van den Broeck K. , Van Gerven T. , Dutré V. , Seuntjens P. , Berghmans P. , Cornelis C. , Nouwen J.
Published: April 2009

Zinc ashes, muffle furnace fragments and lead slags from non-ferrous industries were applied to pave roads in the North of Belgium. From an inventory it appeared that there are at least 490 km of such roads. In our survey the materials on these roads were characterised. The total metal concentration, the availability and the leaching as a function of time were determined. It appeared that these materials contain high concentrations of heavy metals, some of which are readily available. The high leaching of some metals makes them as such unsuitable as secondary construction material.

Methods for the application of these materials for road construction were examined where the materials replaced part of the sand and gravel fraction in lean concrete and in bituminous mixtures, or where they replaced the sand in sand-cement mixtures, all these to be used for road foundations, cycle tracks, etc. When lead slags were applied in lean concrete, a material was obtained complying with the standards for secondary construction materials and with sufficient compressive strength for road foundations. When zinc ashes or muffle fragments were used to replace sand in sand-cement mixtures, again a suitable construction material was obtained. The other combinations tried out were rather unsuccessful, because of high metal leaching and/or poor compressive strength.
Temporal and Spatial Expression of the period Gene in the Reproductive System of the Codling Moth
Authors: Gvakharia Barbara O. , Kilgore Jason A. , Bebas Piotr , Giebultowicz Jadwiga M.
Published: April 2009

The authors examined patterns of spatial and temporal expression of Drosophila per gene homologue in the codling moth, Cydia pomonella. Since sperm release in moths is regulated in a circadian manner by an autonomous clock that is independent from the brain, the authors investigated per expression in male reproductive system along with its expression in moth heads. per mRNA is rhythmically expressed with the same phase and amplitude in both tissues under light-dark (LD) conditions. The levels of per mRNA are low during the day, start to increase before lights-off, reach the peak in dark, and decrease after lights-on. In constant darkness (DD), cycling of per mRNA continued in heads with severely blunted amplitude. No cycling of per mRNA was detected in testis in DD. In situ hybridization and immunocytochemistry revealed distinct spatial patterns of per expression in the moth reproductive system. There is no expression of per in cells forming the wall of testes or in sperm bundles. However, permRNA and protein are rhythmically expressed in the epithelial cells forming the wall of the upper vas deferens (UVD) and in the cells of the terminal epithelium, which are involved in the circadian gating of sperm release. Increase in permRNA in the UVD coincides with sperm accumulation in this part of the insect reproductive system.
Restricted Daytime Feeding Attenuates Reentrainment of the Circadian Melatonin Rhythm after an 8-h Phase Advance of the Light-Dark Cycle
Authors: Kalsbeek A. , Barassin S. , van Heerikhuize J. J. , van der Vliet J. , Buijs R. M.
Published: April 2009

It is well established that in the absence of photic cues, the circadian rhythms of rodents can be readily phase-shifted and entrained by various nonphotic stimuli that induce increased levels of locomotor activity (i.e., benzodiazepines, a new running wheel, and limited food access). In the presence of an entraining light-dark (LD) cycle, however, the entraining effects of nonphotic stimuli on (parts of) the circadian oscillator are far less clear. Yet, an interesting finding is that appropriately timed exercise after a phase shift can accelerate the entrainment of circadian rhythms to the new LD cycle in both rodents and humans. The present study investigated whether restricted daytime feeding (RF) (1) induces a phase shift of the melatonin rhythm under entrained LD conditions and (2) accelerates resynchronization of circadian rhythms after an 8-h phase advance. Animals were adapted to RF with 2-h food access at the projected time of the new dark onset. Before and at several time points after the 8-h phase advance, nocturnal melatonin profiles were measured in RF animals and animals on ad libitum feeding (AL). In LD-entrained conditions, RF did not cause any significant changes in the nocturnal melatonin profile as compared to AL. Unexpectedly, after the 8-h phase advance, RF animals resynchronized more slowly to the new LD cycle than AL animals. These results indicate that prior entrainment to a nonphotic stimulus such as RF may “phase lock” the circadian oscillator and in that way hinder resynchronization after a phase shift.
Probing the Circadian Pacemaker of a Mouse Using Two Light Pulses
Authors: Sharma Vijay Kumar , Chidambaram R. , Chandrashekaran Maroli K.
Published: April 2009

In two separate sets of experiments, the phases of the locomotor activity rhythm of the nocturnal field mouse Mus booduga were probed using two light pulses (LPs). In the first set of experiments, the circadian pacemaker underlying the locomotor activity rhythm was perturbed at circadian time 14 (CT 14) using a resetting light pulse LP1 of 1000 lux intensity and 15 min duration. The phases of the resetting pacemaker were then probed at all even CTs between CT 16 and CT 14 using a PRC probing light pulse LP2 of equal strength. The “LP2PRC” thus obtained was then compared with the single light pulse PRC in terms of the area under delay (D) and advance (A) zones of the PRCs. The time course and waveform of the two LP PRCs suggest that the LP2PRC resembled the single LP PRC, displaced by 2 h toward the right. The LP2PRC had smaller D compared to the single LPPRC ( p = 0.007), whereas both the PRCs had A of equal magnitude ( p = 0.23). This suggests that the pacemaker phase shifts rapidly after LP perturbations. In the second set of experiments, the LP1 was administered at CT 14. The phase of the pacemaker was then perturbed on day 1 (next cycle after LP1) either 2 h after activity onset (at ca. CT 14 of the transient cycle) or 8 h after activity onset (at ca. CT 20 of the transient cycle) using an LP2 of equal strength. It was observed that the steady-state phase shifts evoked by positioning an LP2, 2 h after activity onset, were positively correlated with the phase shifts observed on day 1. The steady-state phase shifts observed, when the LP2 was positioned, 8 h after activity onset, were negatively correlated with the phase shifts observed on day 1. These results suggest that the transient cycles do not mirror the state of the pacemaker oscillator.
What Can the Chronobiologist Do to Help the Shift Worker?
Authors: Monk Timothy H.
Published: April 2009

This article is composed of a review of how the increasing numbers of people working abnormal hours (referred to as “shift workers”) can best be helped by the science of chronobiology. While recognizing that chronobiologists can give much general advice regarding such things as diet, sleep hygiene, cardiovascular health, and the need to address social and domestic tensions, this article will focus specifically on the advice that can be given to employers and employees, which is directly rooted in our knowledge of chronobiology.
Fos in the Suprachiasmatic Nucleus of House Mouse Lines That Reveal a Different Phase-Delay Response to the Same Light Pulse
Authors: Amy Scott P. , Chari Ramya , Bult Abel
Published: April 2009

Increased light intensity of a 5-min light pulse is positively correlated with Fos mRNA and Fos protein levels in the suprachiasmatic nucleus (SCN) of hamsters. These findings suggest that the level of Fos activation is proportional to the light intensity and that the magnitude of the phase-shift response depends on the level of Fos activation. However, to what extent different phase-delay responses to the same light pulse are mediated by differential Fos activation is unknown. To elucidate this, the authors used selected house mouse lines that reveal an almost threefold difference in phase-delay responses in constant darkness (DD) between circadian time (CT) 16 and CT 20 to the same light pulse. The authors measured wheel-running activity and subjected male mice of these lines to a 15-min light pulse at CT 16 after 2 weeks in DD. The behavioral response was measured and 10 to 12 days later the animals were again subjected to the same light pulse at CT 16. One hour after the start of the second light pulse, the animals were sacrificed for Fos immunocytochemistry. Results indicate a significant difference between the lines in the phase-delay response (F2,26 = 5.112, p < 0.017) and the level of Fos activation (F2,26 = 27.15, p < 0.0001) after a 15-min light pulse at CT 16. These findings support the hypothesis that the magnitude of the phase-delay response is proportional to the number of cells in the SCN that exhibit Fos induction after the same 15-min light pulse at CT 16 in DD. It also indicates a possible difference in the input pathways among the lines.
The Effects of Melatonin and L-DOPA on the Diurnal Rhythms of Free Amino Acids Content in the Rat Retina
Authors: Pozdeyev N. V. , Doroshenko E. M. , Lavrikova E. V. , Etingof R. N.
Published: April 2009

The effects of melatonin and dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) intraperitoneal administration on the rhythms of free amino acids content in the retina of rats were studied. The authors found that the levels of those amino acids, which are protein constituents but not neurotransmitters in the rat retina, change diurnally with maximum at 3-6 h after light onset. Diurnal changes of Ala, Arg, Asn, Ile, Met, Ser, Trp, and Val content persisted in the retina of rats maintained at constant darkness. This fact confirms the true circadian nature of these rhythms. Constant lighting abolished diurnal changes of the content of all amino acids with the exception of Trp. Daytime but not nighttime administration of melatonin decreased the levels of Ala, Asn, Gln, Ile, Met, and Ser down to nocturnal values. Diurnal changes of amino acids content vanished in melatonin-injected rats. The effect of melatonin administration disappeared when the protein synthesis was inhibited by cycloheximide. The effect of intraperitoneal administration of L-DOPAon the levels of free amino acids was opposite the effect of melatonin administration. L-DOPA increased nocturnal levels of Gly, Thr, Trp, and Val but had no effect on the daytime amino acids content. As in the case of melatonin administration, significant diurnal changes of amino acid levels disappeared in L-DOPA-injected rats. The authors hypothesize that melatonin and dopamine can serve as zeitgebersantagonists of amino acids content rhythms in the rat retina.
Circadian Ovulatory Rhythms in Japanese Quail: Role of Ocular and Extraocular Pacemakers
Authors: Zivkovic Bora D. , Underwood Herbert , Siopes Thomas
Published: April 2009

Previous studies have shown that the circadian system of Japanese quail is composed of multiple photic inputs and multiple oscillators. Among these are extraretinal photoreceptors that mediate both circadian and photoperiodic responses and circadian pacemakers in the eyes that, via neural and hormonal outputs, help to maintain rhythmicity of central circadian clocks (presumably located in the suprachiasmatic area of the hypothalamus). Furthermore, a component of the central circadian system is influenced by reproductive hormones. Under certain conditions, the circadian system of female quail can be induced to split into two circadian components: one driven by ocular pacemakers and one driven by feedback from reproductive hormones. Importantly, ovulation is either inhibited or permitted as these two oscillators (or sets of oscillators) constantly change internal phase relationships with each other, suggesting an “internal coincidence” mechanism in the control of ovulation. The oviposition patterns of quail in light-dark (LD) cycles also support an internal coincidence mechanism. The authors tested the hypothesis that the ocular pacemakers are an important component of an internal coincidence mechanism controlling ovulation by examining the effects of blinding by complete eye removal (EX), and the effects of eye-patching, on the body temperature and oviposition patterns of quail exposed to 24-h LD cycles. They also examined the effects of EX on quail exposed to continuous light (LL) and to continuous darkness (DD). Neither EX nor eyepatching affected the oviposition patterns of birds in LD. Furthermore, robust body temperature and oviposition rhythms continued in EX birds in LL, but body temperature became arrhythmic in DD with the cessation of ovulation. The results do not show a role for ocular pacemakers in the control of ovulation, but they do support the hypotheses that (1) entrainment of the central oscillators by extraretinally perceived light is sufficient to preserve a normal ovulatory pattern in LD in the absence of the ocular pacemakers, and (2) in LL, feedback of reproductive hormones onto the central oscillators is sufficient to organize the circadian system even in the absence of the ocular pacemakers. Whether or not the ocular pacemakers are normally involved in the control of ovulation is still an open question.
Circadian Rhythms in Neurospora: A New Measurement, the Reset Zone
Authors: Shaw Jonathan , Brody Stuart
Published: April 2009

The authors define a new feature of a circadian rhythm, the reset zone, and point out its usefulness for predictions concerning oscillator behavior. The reset zone measures the responses of a circadian system to resetting pulses. It can be easily determined from a phase transition curve (PTC), which is simply a phase response curve (PRC) replotted as new phase versus old phase (Winfree's format). The reset zone is the range of new phases seen in such a plot and has two potentially useful characteristics: its size and its midpoint. A series of experiments with Neurospora involving temperature pulses indicated that the size of the reset zone changed in a nonlinear way in response to both the duration of 40°C pulses and to the magnitude of temperature change for 3-h pulses. Other existing data are replotted to show how the reset zone size varies with growth temperature and with the period of different clock mutants. Employing exclusively reset zone data within the framework of a limit cycle displacement model, an equation is formulated that predicts the relative changes in the values of state variables of the oscillator for changes in any given environmental condition, such as temperature. Examples are also drawn from other organisms, such as hamsters, Gonyalaux, Kalanchoe, and Drosophila, illustrating the usefulness of the reset zone measurement. It can be used as a numerical scale for assessing the strength of a pulse, for comparing the relative effects of a given pulse applied to different organisms or mutants, for determining the directionality of the changes in state variables produced by various types of pulses, and possibly for measuring clock amplitude.
No Melatonin Suppression by Illumination of Popliteal Fossae or Eyelids
Authors: Jean-Louis Girardin , Kripke Daniel F. , Cole Roger J. , Elliott Jeffrey A.
Published: April 2009

A recent report that popliteal illumination shifted the circadian rhythms of body temperature and melatonin challenged the longstanding belief that light phase-shifting the circadian system in mammals is mediated only through the retina. The authors tested effects of popliteal illumination and illumination provided through the eyelids on melatonin suppression. In randomized, counterbalanced orders, healthy volunteers received three treatments from midnight until 2:00 AM, one on each of three visits to the laboratory. Treatments included (1) no illumination from light pads applied to the popliteal fossae, with light mask maintained at < 3 lux (control); (2) light mask illuminated at 1700 lux, with popliteal light pads extinguished; and (3) popliteal light pads illuminated (13,000 lux) and light mask at < 3 lux (control). Saliva specimens were sampled at midnight, at 1:00 AM, and at 2:00 AM. Mean salivary melatonin concentrations rose from an average of 30.8 (3.9) pg/ml at midnight (baseline), to 33.2 (4.0) pg/ml at 1:00 AM, and to 37.2 (3.8) pg/ml at 2:00 AM in all three conditions, but no statistical differences were found using repeated-measures ANOVA. No evidence of melatonin suppression by either popliteal or closed eyelid light stimulation was found. These data suggest that bright retinal illumination is necessary for suppression of melatonin mediated through the suprachiasmatic nuclei.
Long Photoperiod Restores the 24-h Rhythm of Sleep and EEG Slow-Wave Activity in the Djungarian Hamster (Phodopus sungorus)
Authors: Deboer Tom , Vyazovskiy Vladyslav V. , Tobler Irene
Published: April 2009

Photoperiod influences the distribution of sleep and waking and electroencephalogram (EEG) power density in the Djungarian hamster. In an experimental procedure combining short photoperiod (SP) and low ambient temperature, the light-dark difference in the amount of sleep was decreased, and the changes in slow-wave activity (SWA) (mean EEG power density between 0.75 and 4.0 Hz) in nonrapid eye movement (NREM) sleep within 24 h were abolished. These findings, obtained in three different groups of animals, suggested that at the lower ambient temperature, the influence of the circadian clock on sleep-wake behavior was diminished. However, it remained unclear whether the changes were due to the photoperiod, ambient temperature, or both. Here, the authors show that EEG and electromyogram recordings in a single group of animals sequentially adapted to a short and long photoperiod (LP) at low ambient temperature (~15 °C) confirm that EEG power is reduced in SP. Moreover, the nocturnal sleep-wake behavior and the changes in SWAin NREM sleep over 24 h were restored by returning the animals to LP and retaining ambient temperature at 15 °C. Therefore, the effects cannot be attributed to ambient temperature alone but are due to a combined effect of temperature and photoperiod. When the Djungarian hamster adapts to winter conditions, it appears to uncouple sleep regulation from the circadian clock.
Pseudorabies Virus and the Functional Architecture of the Circadian Timing System
Authors: Card J. Patrick
Published: April 2009

Transneuronal tracing of neuronal circuitry with neurotropic viruses has provided valuable insights in the way in which the nervous system imposes temporal organization on physiological processes and behavior. The swine alpha herpes virus known as pseudorabies virus, or PRV, has been particularly useful in this regard. Early studies identified attenuated mutants with selective tropism for visual circuitry involved in circadian regulation, and subsequent experiments employing this virus have provided considerable insight into the polysynaptic organization of the suprachiasmatic nuclei and associated circuitry. This literature, which has emerged during the past decade, is the subject of this mini review.
The period E-box Is Sufficient to Drive Circadian Oscillation of Transcription In Vivo
Authors: Darlington Thomas K. , Lyons Lisa C. , Hardin Paul E. , Kay Steve A.
Published: April 2009

The minimum element from the Drosophila period promoter capable of driving in vivo cycling mRNA is the 69 bp circadian regulatory sequence (CRS). In cell culture, an 18 bp E-box element from the period promoter is regulated by five genes that are involved in the regulation of circadian expression in flies. This E-box is a target for transcriptional activation by bHLH-PAS proteins dCLOCK (dCLK) and CYCLE (CYC), this activation is inhibited by PERIOD (PER) and TIMELESS (TIM) together, and inhibition of dCLK/CYC by PER and TIM is blocked by CRYPTOCHROME (CRY) in the presence of light. Here, the same 18 bp E-box region generated rhythmic expression of luciferase in flies under both light-dark cycling and constant conditions. Flies heterozygous for the Clk mutation maintained rhythmic expression from the E-box although at a lower level than wild type. Homozygous mutant Clk animals had drastically lowered and arrhythmic expression. In a per background, expression from the E-box was high and not rhythmic. Transcription mediated by the per E-box was restricted to the same spatial pattern as the CRS. The per E-box DNAelement and cognate binding proteins can confer per-like temporal and spatial expression. This demonstrates in vivo that the known circadian genes that form the core of the circadian oscillator in Drosophila integrate their activities at a single DNA element.
Specific Sequences Outside the E-box Are Required for Proper per Expression and Behavioral Rescue
Authors: Lyons Lisa C. , Darlington Thomas K. , Hao Haiping , Houl Jerry , Kay Steve A. , Hardin Paul E.
Published: April 2009

A 69 bp circadian regulatory sequence (CRS) upstream of the per gene is sufficient to drive circadian transcription, mediate proper spatial expression, and rescue behavioral rhythmicity in per01 flies. Within the CRS, an E-box is required for transcriptional activation by two basic-helix-loop-helix (bHLH) PERARNT-SIM (PAS) transcription factors, dCLOCK (dCLK) and CYCLE (CYC). To define sequences within the CRS that are required for spatial expression, circadian expression, and behavioral rhythmicity, a series of mutants that alter blocks of 3 to 12 nucleotides across the entire CRS were used to drive lacZ or per expression in vivo. As expected, the E-box within the CRS is necessary for high-level expression and behavioral rhythmicity, but sequences outside the E-box are also required for transcriptional activation, proper spatial expression, and behavioral rhythmicity. These results indicate that the dCLK-CYC target site extends beyond the E-box and that factors other than dCLK and CYC modulate per transcription.
The Coincidence of Light and Melatonin with a Specific Phase of the Circadian Pacemaker Is Important for the Timing of Seasonal Breeding in the Ewe
Authors: Guerin Michael V. , Deed Jim R. , Matthews Colin D.
Published: April 2009

The timing of reproductive activity in seasonal breeding sheep relies on daily photoperiodic signals being relayed to provide information on the time of year. Although light and melatonin are involved, the exact mechanism is not understood. In this experiment, three groups of 6 Romney Marsh ewes, a highly seasonal breed, were provided with 8 weeks of short nights (9.6-9.8 h, by artificially advancing dawn) around the winter solstice, near the end of their natural breeding season. One group of animals was infused to a physiological level with melatonin for 5 h during the afternoon prior to the onset of dark, while a second group was identically infused but for5hfromthe time of lights on. A third group received the short-night treatment only. Following the short-night treatment, all groups were exposed to long nights (> 14 h, by delaying dawn) until the summer solstice. Ovarian activity, assessed by progesterone monitoring twice weekly, showed that the noninfused and the morning-infused groups displayed renewed reproductive activity in response to the short-night/long-night treatment. There was no renewed ovarian activity in the afternoon-infused group, indicating that the time of day that melatonin is present, rather than the duration of melatonin exposure, is an important signal in the control of reproductive timing. Measurements of a marker of the endogenous circadian pacemaker, by melatonin measurements under acutely extended darkness, revealed that the short-night treatments phase advanced the onset of the pacemaker in all groups such that the afternoon phase of the pacemaker was coincident with light. The results provide strong support for the model that proposes that an afternoon-located sensitive phase of the pacemaker is responsible for the relay of photoperiodic signals in the timing control of seasonal breeding. The model proposes that the reproductive axis be primed during short nights when the sensitive phase is coincident with light in the afternoon so ovarian activity can be induced when the sensitive phase is located within the longer nights of autumn and coincident with endogenous melatonin.
Effects of Aging on the Intrinsic Circadian Period of Totally Blind Humans
Authors: Kendall Adam R. , Lewy Alfred J. , Sack Robert L.
Published: April 2009

Age-related changes in the intrinsic circadian period ([.tau]) have been hypothesized to account for sleep symptoms in the elderly such as early morning awakening. The authors sought to determine whether the aging process produced quantifiable differences in the [.tau] of totally blind men who had free-running circadian rhythms. The melatonin onset was used as the indicator of circadian phase. Melatonin rhythms had been characterized about a decade previously when the participants were 38 ± 6 (SD) years old. Both previous and current assessments of [.tau] were derived from at least 3 serial measurements of the 24-h melatonin profile from which the melatonin onset was determined. All 6 participants exhibited a longer [.tau] in the 2nd assessment (mean increase ± SD of 0.13 ± 0.08 h; p < 0.01). Four participants exhibited differences in [.tau] with nonoverlapping 95% confidence intervals. The results do not support the commonly held view that [.tau] shortens during human aging. On the contrary, [.tau] appears to slightly, but significantly, lengthen during at least 1 decade in midlife.
Postmortem Stability of Melatonin Receptor Binding and Clock-Relevant mRNAs in Mouse Suprachiasmatic Nucleus
Authors: Weaver David R. , Capodice Camala E.
Published: April 2009

The stability of receptor proteins and mRNAs in brain tissue is variable after death. As a prelude to quantitative studies of melatonin receptor density and clock gene expression in the human brain, the stability of these macromolecules was examined in the mouse brain under simulated postmortem conditions using the model of Spokes and Koch (1978). In the mouse suprachiasmatic nucleus (SCN), melatonin receptor binding was significantly reduced after 18 to 24 h under postmortem conditions. Two mRNAs that are rhythmically expressed in the SCN, mPer1 and prepropressophysin ( AVP), also decreased significantly over the interval studied, and mPer1 declined more rapidly than AVP. Both mPer1 and AVP mRNA levels in the SCN declined more rapidly in vivo than under postmortem conditions, suggesting that the degradation of these mRNAs is an active process. The results indicate that quantitative studies of melatonin receptor density on human postmortem material are feasible and that detection of rhythmic gene expression in the human SCN will likely require collection of specimens with a rather short (< 8 h) interval from death to tissue collection. The relative stability of melatonin receptor binding in the SCN also suggests that receptor binding may be a reliable marker for the location of the SCN in studies assessing clock gene expression in postmortem material.
Robust Circadian Rhythmicity of Per1 and Per2 Mutant Mice in Constant Light, and Dynamics of Per1 and Per2 Gene Expression under Long and Short Photoperiods
Authors: Steinlechner Stephan , Jacobmeier Birgit , Scherbarth Frank , Dernbach Haiko , Kruse Friederike , Albrecht Urs
Published: April 2009

The Per1 and Per2 genes are components of the mammalian circadian clock. Mutations in these genes alter phase resetting in response to a nocturnal light pulse, and Per2 mutant mice are known to become arrhythmic in constant darkness. We show that under constant light conditions, Per2 mutant mice exhibit robust activity rhythms as well as body temperature rhythms with a period length that is less than 24 h. In Per1 mutants, the period length of both activity and body temperature rhythms is longer than 24 h in constant light. Per1mutants prolong their period length ([.tau]) when illuminance is increased, whereas Per2 mutants shorten their endogenous period. Additionally, the authors show that the circadian pattern of Per1 and Per2 gene expression in mice is modified under different photoperiods and that there is a mutual influence of these genes on their timing of expression. We propose that, in mice, the phase relationship between Per1 and Per2 gene expression might be critical for transducing day length information to the organism. Per1 could be part of a morning oscillator tracking dawn, and Per2 could be part of an evening oscillator tracking dusk.
Djungarian Hamsters: A Species with a Labile Circadian Pacemaker? Arrhythmicity under a Light-Dark Cycle Induced by Short Light Pulses
Authors: Steinlechner Stephan , Stieglitz Ariane , Ruf Thomas
Published: April 2009

In most cases, phase-shifting effects of light pulses are studied in animals kept in constant darkness (DD) or in animals released into DD following the stimulus. In this study, the authors exposed Djungarian hamsters ( Phodopus sungorus) to short light pulses during the dark phase of a 16:8 light-dark (LD) cycle and thus obtained a type VI phase response curve. Light pulses early in the night caused phase delays of the activity onset as well as phase advances of the activity offset, whereas light pulses later in the night resulted in phase advances of the activity offset only. Acombination of two 15-min light pulses—the first one given late in the scotophase and the second given early in the dark phase of the following night—led to a strong compression of the activity phase [.alpha]. In 75% of all animals, daily rhythms were no longer visible after complete [.alpha] compression, and long-term arrhythmicity (up to 145 days) persisted despite continued exposure to an LD cycle. Because three independent output rhythms of the clock (i.e., activity, body temperature, and melatonin rhythms) were equally affected, the authors conclude that overt arrhythmicity was due not merely to disrupted output pathways but to an altered state of the central pacemaker. The authors suggest a qualitative two-oscillator model to explain this phenomenon. Their hypothesis assumes that, due to loose coupling, the pacemaker of Djungarian hamsters can be driven to a state of zero phase difference between the two oscillators, with zero amplitude of their outputs.
Phase-Dependent Effect of Room Light Exposure in a 5-h Advance of the Sleep-Wake Cycle: Implications for Jet Lag
Authors: Boivin Diane B. , James Francine O.
Published: April 2009

The acute disruption in sleep quality, vigilance levels, and cognitive and athletic performance observed after transmeridian flights is presumed to be the result of a transient misalignment between the endogenous circadian pacemaker and the shifted sleep schedule. Several laboratory and field experiments have demonstrated that exposure to bright artificial light can accelerate circadian entrainment to a shifted sleep-wake schedule. In the present study, the authors investigated whether the schedule of exposure to indoor room light, to which urban dwellers are typically exposed, can substantially affect circadian adaptation to a simulated eastward voyage. We enrolled 15 healthy young men in a laboratory simulation of a Montreal-to-London voyage. Subjects were exposed to 6 h of room light (mean ± SD: 379 ± 10) prior to bedtime ( n = 7) or when on a progressively advancing schedule ( n = 8) early in the day. The remaining 10 hours of wakefulness were spent in dim light (4 ± 1 lux). Circadian assessments, performed via the constant routine procedure, evaluated the phase of the endogenous circadian rhythms of core body temperature and plasma melatonin before and after 1 week on the shifted schedule. At the end of the study, only subjects exposed to room light on the advancing schedule expressed oscillations of the endogenous circadian pacemaker in phase with the new sleep-wake cycle. In this group, a mean advance shift of the nadir of core body temperature of +5:22 ± 0:15 h was observed, with parallel shifts in plasma melatonin concentration and subjective alertness. The circadian rhythms of subjects exposed to room light later in the day remained much more adjusted to the departure than to the destination time zone. These results demonstrate that the schedule of exposure to room light can substantially affect circadian adaptation to a shifted sleep-wake schedule.
Maternal Entrainment of the Developing Circadian System in the Siberian Hamster (Phodopus sungorus)
Authors: Duffield Giles E. , Ebling Francis J. P.
Published: April 2009

The aim of these studies was to investigate maternal entrainment of developing circadian locomotor activity rhythms in the Siberian hamster. In Experiment 1, mothers were transferred from a 16:8 LD cycle into constant dim red light (DD) from the day of parturition, and wheel-running activity of the mother and pups was individually monitored from the time of weaning. The phases of the individual pups’ rhythms were found to be synchronized both to the phase of the mother and to the phase of lights off (ZT 12) of the photo cycle that the mother was exposed to until the day of parturition. To investigate whether this synchrony might reflect direct effects of light acting upon the fetal circadian system in late gestation, the experiment was repeated but with mothers placed into DD early in pregnancy ([.lessequal] day 7 of gestation). The results were similar to the first study, suggesting that the mother rather than the photo cycle during the latter part of gestation entrains the developing circadian system. The third experiment investigated whether this entrainment occurred during the postnatal period. Breeding pairs were maintained on alternative light-dark cycles, LD and DL, that were 12 h out of phase. Litters born to mothers on one light-dark cycle were exchanged on the day of birth with foster mothers from the reversed light-dark cycle, then raised in DD. Control litters exchanged between mothers from the same light-dark cycle had similar litter synchrony as shown by nonfostered litters of Experiment 1. However, pups cross-fostered with mothers on reversed LD cycles showed a very different distribution of pup phases. Pups were not synchronized to their natural mother but to their foster mother. Moreover, pups were more scattered over the 24-h period and were found to be significantly synchronized to the phase of the reversed LD cycle. These results demonstrate the occurrence of postnatal entrainment in the Siberian hamster. The increased scatter produced by the cross-fostering paradigm results from some litters being completely entrained to the phase of the foster mother, some with an intermediate distribution between the phases of the natural and foster mothers, and a minority being associated with the phase of the natural mother. These results suggest that Siberian hamster pups are initially synchronized either prenatally or at birth but that the mother continues to provide entrainment signals during the postnatal period.