Profile order and time-dependent artifacts in contrast-enhanced coronary MR angiography at 3T: origin and prevention.

To enhance the clinical value of coronary magnetic resonance angiography (MRA), high-relaxivity contrast agents have recently been used at 3T. Here we examine a uniform bilateral shadowing artifact observed along the coronary arteries in MRA images collected using such a contrast agent. Simulations were performed to characterize this artifact, including its origin, to determine how best to mitigate this effect, and to optimize a data acquisition/injection scheme. An intraluminal contrast agent concentration model was used to simulate various acquisition strategies with two profile orders for a slow-infusion of a high-relaxivity contrast agent. Filtering effects from temporally variable weighting in k-space are prominent when a centric, radial (CR) profile order is applied during contrast infusion, resulting in decreased signal enhancement and underestimation of vessel width, while both pre- and postinfusion steady-state acquisitions result in overestimation of the vessel width. Acquisition during the brief postinfusion steady-state produces the greatest signal enhancement and minimizes k-space filtering artifacts.

Effect of hypoxia on cerebral blood flow regulation during rest and exercise : role of cerebral oxygen delivery on performance

Adequate supply of oxygen to the brain is critical for maintaining normal brain function. Severe hypoxia, such as that experienced during high altitude ascent, presents a unique challenge to brain oxygen (O2) supply. During high-intensity exercise, hyperventilation-induced hypocapnia leads to cerebral vasoconstriction, followed by reductions in cerebral blood flow (CBF), oxygen delivery (DO2), and tissue oxygenation. This reduced O2 supply to the brain could potentially account for the reduced performance typically observed during exercise in severe hypoxic conditions. The aims of this thesis were to document the effect of acute and chronic exposure to hypoxia on CBF control, and to determine the role of cerebral DO2 and tissue oxygenation in limiting performance during exercise in severe hypoxia. We assessed CBF, arterial O2 content (CaO2), haemoglobin concentration ([Hb]), partial pressure of arterial O2 (PaO2), cerebrovascular CO2 reactivity, ventilatory response to CO2, cerebral autoregulation (CA), and estimated cerebral DO2 (CBF ⨉ CaO2) at sea level (SL), upon ascent to 5,260 m (ALT1), and following 16 days of acclimatisation to 5,260 m (ALT16). We found an increase in CBF despite an elevated cerebrovascular CO2 reactivity at ALT1, which coincided with a reduced CA. Meanwhile, PaO2 was greatly decreased despite increased ventilatory drive at ALT1, resulting in a concomitant decrease in CaO2. At ALT16, CBF decreased towards SL values, while cerebrovascular CO2 reactivity and ventilatory drive were further elevated. Acclimatisation increased PaO2, [Hb], and therefore CaO2 at ALT16, but these changes did not improve CA compared to ALT1. No differences were observed in cerebral DO2 across SL, ALT1, and ALT16. Our findings demonstrate that cerebral DO2 is maintained during both acute and chronic exposure to 5,260 m, due to the reciprocal changes in CBF and CaO2. We measured middle cerebral artery velocity (MCAv: index of CBF), cerebral DO2, ventilation (VE), and performance during incremental cycling to exhaustion and 15km time trial cycling in both normoxia and severe hypoxia (11% O2, normobaric), with and without added CO2 to the inspirate (CO2 breathing). We found MCAv was higher during exercise in severe hypoxia compared in normoxia, while cerebral tissue oxygenation and DO2 were reduced. CO2 breathing was effective in preventing the development of hyperventilation-induced hypocapnia during intense exercise in both normoxia and hypoxia. As a result, we were able to increase both MCAv and cerebral DO2 during exercise in hypoxia with our CO2 breathing setup. However, we concomitantly increased VE and PaO2 (and presumably respiratory work) due to the increased hypercapnic stimuli with CO2 breathing, which subsequently contributed to the cerebral DO2 increase during hypoxic exercise. While we effectively restored cerebral DO2 during exercise in hypoxia to normoxic values with CO2 breathing, we did not observe any improvement in cerebral tissue oxygenation or exercise performance. Accordingly, our findings do not support the role of reduced cerebral DO2 in limiting exercise performance in severe hypoxia. -- Un apport adéquat en oxygène au niveau du cerveau est primordial pour le maintien des fonctions cérébrales normales. L'hypoxie sévère, telle qu'expérimentée au cours d'ascensions en haute altitude, présente un défi unique pour l'apport cérébral en oxygène (O2). Lors d'exercices à haute intensité, l'hypocapnie induite par l'hyperventilation entraîne une vasoconstriction cérébrale suivie par une réduction du flux sanguin cérébral (CBF), de l'apport en oxygène (DO2), ainsi que de l'oxygénation tissulaire. Cette réduction de l'apport en O2 au cerveau pourrait potentiellement être responsable de la diminution de performance observée au cours d'exercices en condition d'hypoxie sévère. Les buts de cette thèse étaient de documenter l'effet de l'exposition aiguë et chronique à l'hypoxie sur le contrôle du CBF, ainsi que de déterminer le rôle du DO2 cérébral et de l'oxygénation tissulaire comme facteurs limitant la performance lors d'exercices en hypoxie sévère. Nous avons mesuré CBF, le contenu artériel en oxygène (CaO2), la concentration en hémoglobine ([Hb]), la pression partielle artérielle en O2 (PaO2), la réactivité cérébrovasculaire au CO2, la réponse ventilatoire au CO2, et l'autorégulation cérébrale sanguine (CA), et estimé DO2 cérébral (CBF x CaO2), au niveau de la mer (SL), au premier jour à 5.260 m (ALT1) et après seize jours d'acclimatation à 5.260 m (ALT16). Nous avons trouvé des augmentations du CBF et de la réactivité cérébrovasculaire au CO2 après une ascension à 5.260 m. Ces augmentations coïncidaient avec une réduction de l'autorégulation cérébrale. Simultanément, la PaO2 était grandement réduite, malgré l'augmentation de la ventilation (VE), résultant en une diminution de la CaO2. Après seize jours d'acclimatation à 5.260 m, le CBF revenait autour des valeurs observées au niveau de la mer, alors que la réactivité cérébrovasculaire au CO2 et la VE augmentaient par rapport à ALT1. L'acclimatation augmentait la PaO2, la concentration en hémoglobine, et donc la CaO2, mais n'améliorait pas l'autorégulation cérébrale, comparé à ALT1. Aucune différence n'était observée au niveau du DO2 cérébral entre SL, ALT1 et ALT16. Nos résultats montrent que le DO2 cérébral est maintenu constant lors d'expositions aiguë et chronique à 5.260m, ce qui s'explique par la réciprocité des variations du CBF et de la CaO2. Nous avons mesuré la vitesse d'écoulement du sang dans l'artère cérébrale moyenne (MCAv : un indice du CBF), le DO2 cérébral, la VE et la performance lors d'exercice incrémentaux jusqu'à épuisement sur cycloergomètre, ainsi que des contre-la-montres de 15 km en normoxie et en hypoxie sévère (11% O2, normobarique) ; avec ajout ou non de CO2 dans le mélange gazeux inspiré. Nous avons trouvé que MCAv était plus haute pendant l'exercice hypoxique, comparé à la normoxie alors que le DO2 cérébral était réduit. L'ajout de CO2 dans le gaz inspiré était efficace pour prévenir l'hypocapnie induite par l'hyperventilation, qui se développe à l'exercice intense, à la fois en normoxie et en hypoxie. Nous avons pu augmenter MCAv et le DO2 cérébral pendant l'exercice hypoxique, grâce à l'ajout de CO2. Cependant, nous avons augmenté la VE et la PaO2 (et probablement le travail respiratoire) à cause de l'augmentation du stimulus hypercapnique. Alors que nous avons, grâce à l'ajout de CO2, efficacement restauré le DO2 cérébral au cours de l'exercice en hypoxie à des valeurs obtenues en normoxie, nous n'avons observé aucune amélioration dans l'oxygénation du tissu cérébral ou de la performance. En conséquence, nos résultats ne soutiennent pas le rôle d'un DO2 cérébral réduit comme facteur limitant de la performance en hypoxie sévère.

Effect of mating history on gender preference in the hermaphroditic snail physa acuta

Several internally fertilizing hermaphroditic animals can only perform one sexual role at a time. In such species, two individuals that engage in a copulation may have different interests in acting as male or female. A gender choice must be made which, if both individuals have the same preference, may give rise to a severe sexual conflict. Here we tested the hypothesis that gender choice could be influenced by mating history, using the freshwater snail, Physa acuta. We recorded the copulatory behaviour of 240 pairs composed of a focal individual and a partner, each either short- or long-isolated. We found that the time to the first copulation was unaffected by isolation status, suggesting that first contacts in this species are random processes. In contrast, the duration of copulations and the frequency of rejection behaviours suggested that individual gender preference switches from male biased to female biased as isolation increases. In addition, snails rejected copulations more frequently when presented to a partner with the same isolation status. Reciprocity, measured as the rate of gender swapping between the first and second copulations, was high irrespective of gender status. We suggest possible evolutionary causes for this gender preference switch and discuss its potential importance in natural population as well as its consequences for the maintenance of hermaphroditism

Effect of Pcbs (Aroclor 1254) on spermatogenesis In Testis Of Mouse

Polychlorinated biphenyls (PCBs) are a group of halogenated aromatic hydrocarbons, synthetic chemicals which do not occur naturally in the environment. PCBs are considered potential endocrine disruptors. They are estrogen-like and anti-androgenic chemicals in the environment contain potentially hazardous effects on male reproductive axis resulting in infertility and other hormonal dependent reproductive functions. These toxic substance cause alteration of the endocrine systems, mimic natural hormones and inhibit the action of hormones. The aim of this study is to examine the effect of Polychlorinated biphenyls (PCBs) on testicular development of male reproductive system in mice. The male mice were randomly assigned to five groups with each group comprising twenty-one members. In those mice were administered 0 μg/kg (control group) and 0.5, 5, 50, 500 μg/kg Aroclor 1254 (treated group) by gavages three time per week. Treatment was carried out for 50 days after which the mouse was sacrificed and the body weight, testicular weight; epedidymis weight, sperm mortality, sperm count and sperm abnormality were taken. However, there was no significant difference in testicular/body weight and epididymis/body weight ratio in treated group compared with the control group. According to the analysis of sperm quality, Aroclor 1254 treated group demonstrated significant increased in sperm mortality in 500 μg/kg; decreased the sperm count in 0.5 μg/kg, 5 μg/kg, 50 μg/kg and 500 μg/kg; and significantly elevate the sperm abnormality in 50 μg/kg and 500 μg/kg compared to the control in a dose-dependent manner. The sex hormone levels in the testes were detected by radio-immunoassay (RIA) method. The levels of testosterone and 17β-estradiol did not reveal significant alteration (p< 0.05) in PCBs treated groups compared to the control in a dose-dependent manner. The testis were obtained and subjected to routine histopathology following exposure to PCBs in supplement diet. The diameter of the seminiferous tubule and the number of Sertoli cells in the treated group increased significantly (p< 0.05) in comparison to the control group. For the spermatogenic cell, the number of germ cell in high concentration decreased significantly (p< 0.05). However, spermatogonia cells in PCB treated group showed non-significant difference (p< 0.05) compared to the control. vii Western blot analysis was used to determine the level of protein between the control and treated group. The level of Proliferating cell nuclear antigen (PCNA) was determined and the results have shown no significant alteration between the treated groups and the control. the level of sex hormone receptor (ER α/β); Androgen receptor (AR) were identified in the testes to detect the proliferative effect induced by PCBs. Statistical analyses of AR, ER α and ER β did not reveal significant difference between the control and the treated groups. In the present study, we continue to investigate adverse effect of Aroclor 1254 and their mechanism on spermatogenesis. The result of Sperm quality and histopathology showed that Aroclor 1254 at low concentration induce inhibitory effect on testicular function of male mouse.

Effect of reducing sensory and environmental stimuli during hospitalized premature infant sleep

OBJECTIVETo compare the total sleep time of premature infant in the presence or absence of reducing sensory and environmental stimuli in the neonatal unit.METHODLongitudinal study in a Neonatal Intermediate Care Unit of a public hospital in Sao Paulo. The sample consisted of 13 premature infants. We used polysomnograph and unstructured observation for data collection. We analyzed 240 and 1200 minutes corresponding to the periods of the presence and absence of environmental management, respectively. Data were compared in proportion to the total sleep time in the two moments proposed by the study.RESULTSThe total sleep time in periods without environmental management was on average 696.4 (± 112.1) minutes and with management 168.5 (± 27.9) minutes, proportionally premature infant slept an average of 70.2% during periods with no intervention and 58.0% without management (p=0.002).CONCLUSIONReducing stimulation and handling of premature infant environment periods was effective to provide greater total sleep time.

Dispersal strategies, few dominating or many coexisting: the effect of environmental spatial structure and multiple sources of mortality.

Interspecific competition, life history traits, environmental heterogeneity and spatial structure as well as disturbance are known to impact the successful dispersal strategies in metacommunities. However, studies on the direction of impact of those factors on dispersal have yielded contradictory results and often considered only few competing dispersal strategies at the same time. We used a unifying modeling approach to contrast the combined effects of species traits (adult survival, specialization), environmental heterogeneity and structure (spatial autocorrelation, habitat availability) and disturbance on the selected, maintained and coexisting dispersal strategies in heterogeneous metacommunities. Using a negative exponential dispersal kernel, we allowed for variation of both species dispersal distance and dispersal rate. We showed that strong disturbance promotes species with high dispersal abilities, while low local adult survival and habitat availability select against them. Spatial autocorrelation favors species with higher dispersal ability when adult survival and disturbance rate are low, and selects against them in the opposite situation. Interestingly, several dispersal strategies coexist when disturbance and adult survival act in opposition, as for example when strong disturbance regime favors species with high dispersal abilities while low adult survival selects species with low dispersal. Our results unify apparently contradictory previous results and demonstrate that spatial structure, disturbance and adult survival determine the success and diversity of coexisting dispersal strategies in competing metacommunities.

The Effect of Four-Lane to Three-Lane Conversion on the Number of Crashes and Crash Rates in Iowa Roads, June 2005

We analyze crash data collected by the Iowa Department of Transportation using Bayesian methods. The data set includes monthly crash numbers, estimated monthly traffic volumes, site length and other information collected at 30 paired sites in Iowa over more than 20 years during which an intervention experiment was set up. The intervention consisted in transforming 15 undivided road segments from four-lane to three lanes, while an additional 15 segments, thought to be comparable in terms of traffic safety-related characteristics were not converted. The main objective of this work is to find out whether the intervention reduces the number of crashes and the crash rates at the treated sites. We fitted a hierarchical Poisson regression model with a change-point to the number of monthly crashes per mile at each of the sites. Explanatory variables in the model included estimated monthly traffic volume, time, an indicator for intervention reflecting whether the site was a “treatment” or a “control” site, and various interactions. We accounted for seasonal effects in the number of crashes at a site by including smooth trigonometric functions with three different periods to reflect the four seasons of the year. A change-point at the month and year in which the intervention was completed for treated sites was also included. The number of crashes at a site can be thought to follow a Poisson distribution. To estimate the association between crashes and the explanatory variables, we used a log link function and added a random effect to account for overdispersion and for autocorrelation among observations obtained at the same site. We used proper but non-informative priors for all parameters in the model, and carried out all calculations using Markov chain Monte Carlo methods implemented in WinBUGS. We evaluated the effect of the four to three-lane conversion by comparing the expected number of crashes per year per mile during the years preceding the conversion and following the conversion for treatment and control sites. We estimated this difference using the observed traffic volumes at each site and also on a per 100,000,000 vehicles. We also conducted a prospective analysis to forecast the expected number of crashes per mile at each site in the study one year, three years and five years following the four to three-lane conversion. Posterior predictive distributions of the number of crashes, the crash rate and the percent reduction in crashes per mile were obtained for each site for the months of January and June one, three and five years after completion of the intervention. The model appears to fit the data well. We found that in most sites, the intervention was effective and reduced the number of crashes. Overall, and for the observed traffic volumes, the reduction in the expected number of crashes per year and mile at converted sites was 32.3% (31.4% to 33.5% with 95% probability) while at the control sites, the reduction was estimated to be 7.1% (5.7% to 8.2% with 95% probability). When the reduction in the expected number of crashes per year, mile and 100,000,000 AADT was computed, the estimates were 44.3% (43.9% to 44.6%) and 25.5% (24.6% to 26.0%) for converted and control sites, respectively. In both cases, the difference in the percent reduction in the expected number of crashes during the years following the conversion was significantly larger at converted sites than at control sites, even though the number of crashes appears to decline over time at all sites. Results indicate that the reduction in the expected number of sites per mile has a steeper negative slope at converted than at control sites. Consistent with this, the forecasted reduction in the number of crashes per year and mile during the years after completion of the conversion at converted sites is more pronounced than at control sites. Seasonal effects on the number of crashes have been well-documented. In this dataset, we found that, as expected, the expected number of monthly crashes per mile tends to be higher during winter months than during the rest of the year. Perhaps more interestingly, we found that there is an interaction between the four to three-lane conversion and season; the reduction in the number of crashes appears to be more pronounced during months, when the weather is nice than during other times of the year, even though a reduction was estimated for the entire year. Thus, it appears that the four to three-lane conversion, while effective year-round, is particularly effective in reducing the expected number of crashes in nice weather.

Negativity effect and the emergence of ideologies

``Negativity effect'' refers to the psychological phenomenon that peopletend to attach greater weight to negative information than to equallyextreme and equally likely positive information in a variety of informationprocessing tasks. Numerous studies of impression formation have found thatnegative information is weighted more heavily than positive information asimpressions of others are formed. There is empirical evidence in politicalscience that shows the importance of the negativity effect in the informationprocessing of the voters. This effect can explain the observed decreaseof popularity for a president the longer he is in office. \\We construct a dynamic model of political competition, incorporating thenegativity effect in the decision rule of the voters and allowing their preferencesto change over time, according to the past performance of the candidateswhile in office. Our model may explain the emergence of ideologies out ofthe competition for votes of myopic candidates freely choosing policypositions. This result gives rise to the formation of political parties,as infinitely--lived agents with a certain ideology. Furthermore, in thismodel some voters may start out by switching among parties associated withdifferent policies, but find themselves supporting one of the parties fromsome point on. Thus, the model describes a process by which some votersbecome identified with a ``right'' or ``left'' bloc, while others ``swing''between the two parties.

Time-Lapse AFM Imaging of DNA Conformational Changes Induced by Daunorubicin.

Cancer is a major health issue that absorbs the attention of a large part of the biomedical research. Intercalating agents bind to DNA molecules and can inhibit their synthesis and transcription; thus, they are increasingly used as drugs to fight cancer. In this work, we show how atomic force microscopy in liquid can characterize, through time-lapse imaging, the dynamical influence of intercalating agents on the supercoiling of DNA, improving our understanding of the drug's effect.

Hypotensive effect of the active fragment derived from factor XII is mediated by an activation of the plasma kallikrein-kinin system.

Plasma protein fraction (PPF) contaminated by factor XII active fragment (XIIf) may cause hypotensive reactions when infused to patients. This study was planned to assess in conscious normotensive rats whether the blood pressure response to the factor XIIf is mediated by an activation of the plasma kallikrein-kinin system or by stimulation of prostaglandin synthesis. To test whether the factor XIIf-induced blood pressure fall is due partially to an enhanced generation of vasodilating prostaglandins, the blood pressure effect of XIIf (1 microgram i.v.) was investigated 15 min after treatment with indomethacin (5 mg i.v.), an inhibitor of cyclo-oxygenase. Factor XIIf reduced mean blood pressure similarly in indomethacin- and vehicle-treated rats (-23 +/- 4 mmHg, n = 5, and -23 +/- 5 mmHg, n = 4, respectively). Other rats received factor XIIf 15 min after depletion of circulating prekallikrein by the administration of dextran sulfate. Thirty minutes after a 0.25 mg i.v. dose of this agent, plasma prekallikrein activity averaged 0.12 +/- 0.015 mumol/min/ml (n = 6) as compared to 2.48 +/- 0.31 mumol/min/ml in control rats (n = 4, P less than .001). Factor XIIf decreased mean blood pressure by only 4 +/- 2 mm Hg in rats pretreated with dextran sulfate. Thus, it was possible to blunt the acute hypotensive effect of factor XIIf by depleting circulating prekallikrein, but not by inhibiting prostaglandin production. This strongly suggests that the blood pressure effects of factor XIIf is mediated by a stimulation of the plasma kallikrein-kinin system.

The effect of divorce laws on divorce rates in Europe

This paper analyzes a panel of 18 European countries spanning from 1950 to 2003 toexamine the extent to which the legal reforms leading to easier divorce that took placeduring the second half of the 20th century have contributed to the increase in divorce rates across Europe. We use a quasi-experimental set-up and exploit the different timing of the reforms in divorce laws across countries. We account for unobserved country-specificfactors by introducing country fixed effects, and we include country-specific trends tocontrol for time-varying factors at the country level that may be correlated with divorcerates and divorce laws, such as changing social norms or slow moving demographictrends. We find that the reforms were followed by significant increases in divorce rates.Overall, we estimate that the introduction of no-fault, unilateral divorce increased thedivorce rate by about 1, a sizeable effect given the average rate of 4.2 divorces per 1,000married people in 2002.

A Hull and White formula for a general stochastic volatility jump-diffusion model with applications to the study of the short-time behavior of the implied volatility

In this paper, generalizing results in Alòs, León and Vives (2007b), we see that the dependence of jumps in the volatility under a jump-diffusion stochastic volatility model, has no effect on the short-time behaviour of the at-the-money implied volatility skew, although the corresponding Hull and White formula depends on the jumps. Towards this end, we use Malliavin calculus techniques for Lévy processes based on Løkka (2004), Petrou (2006), and Solé, Utzet and Vives (2007).

Functional response of Telenomus remus Nixon(Hymenoptera, Scelionidae) to Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae) eggs: effect of female age

Functional response of Telenomus remus Nixon (Hymenoptera, Scelionidae) to Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae) eggs: effect of female age. Functional response of 24-h and 48-h-old Telenomus remus adults was studied on Spodoptera frugiperda eggs. The study was carried out in climatic chamber regulated at 25 ± 1°C, 70 ± 10% RH and 12:12h (L: D). Females of T. remus were honey fed and individualized in glass vials along with 25, 50, 75, 100, 150, 200, 250 or 300 eggs of S. frugiperda for 24 h. Complete randomized design with ten replications was adopted. The parameters evaluated to construct the functional response curve were daily average parasitism, searching rate and oviposition time. It was observed that the higher the egg density, the higher the parasitism for 24-h and 48-h-old females although there was a tendency of parasitism stabilization at 150-egg density. The results showed a type II functional response curve for both 24-h and 48-h-old female.

Synergistic effect of calcitriol and interferon-α on hepatitis C virus replication in vitro

Background and aims: V itamin D is an important modulator o fnumerous c ellular processes, including innate and adaptive immunepathways. A recent large-scale genetic validation study performed withinthe framework of the Swiss Hepatitis C Cohort S tudy has demonstratedan association between t he 1α-hydroxylase promoter single nucleotidepolymorphism CYP27B1-1260 rs10877012 and sustained virologicresponse (SVR) after pegylated interferon-α ( PEG-IFN-α) plus ribavirintreatment of c hronic hepatitis C in patients w ith a p oor-response IL28Bgenotype. This suggests an intrinsic role o f vitamin D signaling in theresponse t o treatment of chronic hepatitis C, especially in patients withlimited sensitivity to IFN-α. In the present study, we investigated theeffect of 1,25-(OH)2 v itamin D3 (calcitriol) alone or in combination withIFN-α on the hepatitis C virus (HCV) life cycle in vitro.Methods: H uh-7.5 cells harboring Con1- or JFH-1-derived HCVreplicons or cell culture-derived HCV were exposed to 0.1-100 nMcalcitriol ± 1 -100 IU/ml IFN-α. The effect on HCV RNA replication andviral particle production was investigated by quantitative r eal-time PCR,immunoblot analyses, and infectivity titration analyses. The expression ofinterferon-stimulated genes (ISGs) and of calcitriol target genes wasassessed by quantitative real-time PCR.Results: Calcitriol had no relevant effect on the viability of Huh-7.5 cells.Calcitriol strongly induced and repressed the expression of the calcitrioltarget genes CYP24A1 and CCNC, respectively, confirming that Huh-7.5cells c an respond to c alcitriol signaling. P hysiological doses of calcitrioldid not significantly a ffect HCV RNA replication or i nfectious particleproduction in vitro, and calcitriol alone h ad no significant effect on theexpression of several ISGs. However, calcitriol in combination with IFN-αsubstantially increased the expression of ISGs compared to IFN-α alone.In addition, calcitriol plus IFN-α s ynergistically inhibited HCV RNAreplication.Conclusions: C alcitriol at physiological concentrations and IFN-α a ctsynergistically on the expression of I SGs and HCV RNA replication i nvitro. Experiments exploring the underlying mechanisms are underway.

The role of incidental variables of time in mood assessment

Determining what influences mood is important for theories of emotion and research onsubjective well-being. We consider three sets of factors: activities in which people areengaged; individual differences; and incidental variables that capture when mood ismeasured, e.g., time-of-day. These three factors were investigated simultaneously in a studyinvolving 168 part-time students who each responded 30 times in an experience samplingstudy conducted over 10 working days. Respondents assessed mood on a simple bipolarscale from 1 (very negative) to 10 (very positive). Activities had significant effects but,with the possible exception of variability in the expression of mood, no systematicindividual differences were detected. Diurnal effects, similar to those already reported inthe literature, were found as was an overall Friday effect. However, these effects weresmall. Lastly, the weather had little or no influence. We conclude that simple measures ofoverall mood are not greatly affected by incidental variables.