bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental variation influences the magnitude of inbreeding depression in Cucurbita pepo ssp. texana (Cucurbitaceae)
Authors: Nelson Hayes C. , Winsor James A. , Stephenson Andrew G.
Published: January 2005

We grew inbred and outcrossed Cucurbita pepo ssp. texana plants and measured inbreeding depression for several male and female fitness traits 4 years in a row in adjacent fields at the same field station under the same cultivation conditions. We found that the magnitude of inbreeding depression varied from 0.16 to 0.53 from year to year and that those traits which were most affected tended to vary with year. We also grew inbred and outcrossed C. pepo ssp. texana plants in two adjacent fields differing only in the presence of nitrogen fertilizer to examine the effect of nutrient limitation as a form of environmental stress on the magnitude of inbreeding depression. We found that inbreeding depression was more severe in the unfertilized field. Overall, this study illustrates the notion that any estimate of inbreeding depression represents a single point in a cluster of possible estimates that can vary (often dramatically) with growing conditions.
Spatial and temporal patterns of parthenogenesis and parasitism in the freshwater snail Melanoides tuberculata
Authors: Ben‐Ami F. , Heller J.
Published: January 2005

The Red Queen hypothesis predicts that sex should be more common in populations heavily infested with parasites, than in those without. This hypothesis was investigated in the aquatic snail Melanoides tuberculata, in which both sexual and parthenogenetic individuals exist in natural populations, and some populations are heavily infested by trematodes. The presence of fertile males and the higher genetic diversity of bisexual populations are indicative of sexual reproduction. We compared sites in 1990, 1999, and 2001, and we looked for a positive correlation between male and parasite frequencies. Male frequency was not correlated with the frequency of individuals infected by trematodes. This lack of correlation was reconfirmed in a retrospective power analysis. In a period of 9 years, male frequencies decreased but infection levels increased. These results do not support the Red Queen hypothesis. In samples with high male frequency the number of embryos was low, perhaps indicating that males may have a negative effect on embryo numbers. This effect of males on fitness could perhaps suggest that the cost of sex is fewer embryos. The reduction in embryo numbers may also represent a trade‐off between mating and egg production costs.
Pitfalls in experiments testing predictions from sperm competition theory
Authors: Engqvist L. , Reinhold K.
Published: January 2005

As females of many species mate with more than one male, ejaculates often face competition from the sperm of other males. In recent years, numerous papers have been published on theoretical predictions of evolutionary, behavioural and physiological responses to variation in the strength of sperm competition (SC). These theoretical predictions have also been extensively tested. However, although predictions from SC theory are relatively straightforward, extra caution has to be paid in the design of experiments testing them. One difficulty is for example to disentangle immediate and mean SC risk and intensity. Without carefully designed experiments, it is also very easy to simultaneously increase SC risk and the probability of intense SC – a situation for which we currently have no clear predictions, as the theoretical models to date only assume variation in either SC risk or intensity. In this paper, we discuss these and some other pitfalls related to manipulations of SC risk and intensity and suggest how to avoid them.
Population differentiation and hybrid success inCampanula americana: geography and genome size
Authors: Galloway L. F. , Etterson J. R.
Published: January 2005

Populations within a species may diverge through genetic drift and natural selection. Few studies report on population differentiation in autopolyploids where multiple gene copies and the ratio of cytoplasmic to nuclear genes differ from diploids and may influence divergence. In autotetraploidCampanula americanawe created hybrids between populations that differed in geographic proximity and genome size. Differences in genome size (up to 6.5%) did not influence hybrid performance. In contrast, hybrid performance was strongly influenced by population proximity. F1 hybrids between distant populations performed poorly relative to their parents while hybrids between proximate populations outperformed their parents. Outbreeding depression was strongest for juvenile traits. The expression of outbreeding depression often differed between reciprocal hybrids indicating interactions between nuclear and cytoplasmic genes contribute to population differentiation. Because plants were grown under greenhouse conditions, the outbreeding depression was likely due to genetic (underdominance or loss of additive‐by‐additive epistasis) rather than ecological factors.
Covariation between brain size and immunity in birds: implications for brain size evolution
Authors: Møller A. P. , Erritzøe J. , Garamszegi L. Z.
Published: January 2005

Parasitism can negatively affect learning and cognition, setting the scene for coevolution between brain and immunity. Greater susceptibility to parasitism by males may impair their cognitive ability, and relatively greater male investment in immunity could compensate for greater susceptibility to parasites, in particular when males have a relatively large brain. We analysed covariation between relative size of immune defence organs and brain in juvenile and adult birds. The relative size of the bursa of Fabricius and the spleen in adults covaried positively with relative brain size across bird species. The relative size of these two immune defence organs covaried with sex differences in relative size of the brain, indicating that the relationship between immune defence and brain size was stronger for males. In contrast, liver and heart size or sexual size dimorphism in size did not covary with immune defence. Thus, species in which males have relatively large brains also have relatively large immune defence organs.
Granule cell number, cell death and cell proliferation in the dentate gyrus of wild‐living rodents
Authors: Amrein Irmgard , Slomianka Lutz , Lipp Hans‐Peter
Published: January 2005

Adult neurogenesis in the dentate gyrus occurs at species‐specific levels. Wood mice (Apodemus flavicollis) show higher proliferation rates than laboratory mice and voles (Clethrionomys glareolus, Microtus subterraneus). We compare rates of cell death and proliferation and investigate if cell proliferation leads to the long‐term recruitment of granule cells. Granule and pyknotic cell numbers were estimated in wild‐living rodents in different age classes and compared with laboratory mice of mixed genetic background. All species differ significantly in their number of granule cells, except for the comparison of laboratory mice with European pine voles. Granule cell number is significantly higher in old bank voles and wood mice as compared to adults (23 and 37%, respectively). The number of pyknotic cells is highest in wood mice and lowest in laboratory mice. Across all species, the numbers of proliferating and pyknotic cells correlate. Despite differences in cell proliferation and cell death, the ratio of proliferating to pyknotic cells does not differ between adults of the wild‐living species, but in laboratory mice a significantly lower proportion of cells die compared with the other species. In addition, the ratio of proliferating to pyknotic cells was significantly higher in old wood mice than in adults. We conclude (i) that cell proliferation can lead to an increase in granule cell number in wild‐living rodents and (ii) that species‐ and age‐specific changes of the ratio between proliferating and pyknotic cells occur as deviations from a close correlation of these two numbers across all species and age groups.
Regulation of the lateral wall stiffness by acetylcholine and GABA in the outer hair cells of the guinea pig
Authors: Batta Tamás József , Panyi György , Szűcs Attila , Sziklai István
Published: January 2005

Acetylcholine (ACh) and GABA, the main neurotransmitters of the efferent innervation of the outer hair cells (OHCs), are assumed to regulate the efficacy of the cochlear amplifier through a variety of mechanisms. The recently described stretch‐induced changes of the lateral wall stiffness (regulatory stiffness response) and the stretch‐induced slow cell motility of OHCs may be important regulatory mechanisms in this process [J.T. Batta et al. (2003) Eur. J. Physiol. 424, 328–336]. We found that ACh in cochleobasal OHCs significantly reduces the stiffness of the lateral wall but increases the regulatory stiffness response and stretch‐induced slow cell motility. Qualitatively similar cellular responses were evoked by GABA in cochleoapical OHCs. The effects of ACh could be inhibited by strychnine, the specific inhibitor of the α9 ACh receptors expressed in OHCs, whereas the effects of GABA could be blocked by bicuculline, a specific GABAA receptor antagonist. In the absence of extracellular Ca2+ the effects of ACh and GABA on the regulatory stiffness response were reduced, indicating the involvement of Ca2+ in the control of this process. Based on our results we suggest that efferent innervation protects the organ of Corti against high sound intensities and supports adaptation by modification of the micromechanical properties of OHCs. This could be governed by ACh and GABA indirectly, via the potentiation of stretch‐induced cell shortening in a Ca2+‐dependent manner, rather than by a direct stiffness regulation‐related mechanism.
Fractalkine reduces N‐methyl‐d‐aspartate‐induced calcium flux and apoptosis in human neurons through extracellular signal‐regulated kinase activation
Authors: Deiva Kumaran , Geeraerts Thomas , Salim Hassan , Leclerc Philippe , Héry Christiane , Hugel Bénédicte , Freyssinet Jean‐Marie , Tardieu Marc
Published: January 2005

Our purpose was to investigate in human neurons the neuroprotective pathways induced by Fractalkine (FKN) against glutamate receptor‐induced excitotoxicity. CX3CR1 and FKN are expressed constitutively in the tested human embryonic primary neurons and SK‐N‐SH, a human neuroblastoma cell line. Microfluorometry assay demonstrated that CX3CR1 was functional in 44% of primary neurons and in 70% of SK‐N‐SH. Fractalkine induced ERK1/2 phosphorylation within 1 min and Akt phosphorylation after 10 min, and both phosphorylation decreased after 20 min. No p38 and SAPK/JNK activation was observed after FKN treatment. Application of FKN triggered a 53% reduction of the NMDA‐induced neuronal calcium influx, which was insensitive to pertussis toxin and LY294002 an inhibitor of Akt pathway, but abolished by PD98059, an ERK1/2 pathway inhibitor. Moreover, FKN significantly reduced neuronal NMDA‐induced apoptosis, which was pertussis toxin insensitive and abolished in presence of PD98059 and LY294002. In conclusion, FKN protected human neurons from NMDA‐mediated excitotoxicity in at least two ways with different kinetics: (i) an early ERK1/2 activation which reduced NMDA‐mediated calcium flux; and (ii), a late Akt activation associated with the previously induced ERK1/2 activation.
Low‐voltage‐activated A‐current controls the firing dynamics of mouse hypothalamic orexin neurons
Authors: Burdakov Denis , Alexopoulos Haris , Vincent Angela , Ashcroft Frances M.
Published: January 2005

The activity of hypothalamic neurons that release the neuropeptides orexin‐A and orexin‐B is essential for normal wakefulness. Orexin neurons fire spontaneously and are hyperpolarized and inhibited by physiological neuromodulators, but the intrinsic determinants of their electrical activity are poorly understood. We show that mouse orexin neurons coexpress orexin‐A and orexin‐B, and possess a low‐voltage‐activated A‐type K+ current (A‐current) likely to be composed of Kv4.3 subunits. The A‐current enhances the inhibitory influence of hyperpolarizing currents via two mechanisms: by delaying the resumption of spiking after hyperpolarization and by increasing the slope of the relation between the firing frequency and injected current. These results identify an important determinant of the firing dynamics of orexin neurons, and support the idea that the A‐current can control neuronal gain.
Estimating the Rank of the Spectral Density Matrix
Authors: Camba‐Mendez Gonzalo , Kapetanios George
Published: January 2005

Abstract. The rank of the spectral density matrix conveys relevant information in a variety of statistical modelling scenarios. This note shows how to estimate the rank of the spectral density matrix at any given frequency. The method presented is valid for any hermitian positive definite matrix estimate that has a normal asymptotic distribution with a covariance matrix the rank of which is known.
Unit‐root testing against the alternative hypothesis of up to m structural breaks
Authors: Kapetanios George
Published: January 2005

Abstract.  In this paper we provide tests for the unit‐root hypothesis against the occurrence of an unspecified number of breaks which may be larger than 2 but smaller that the maximum number of breaks allowed, m, in univariate time‐series models. The advocated procedure is considerably less computationally intensive than those widely used in the literature. We provide critical values for the test and examine its small sample properties through Monte Carlo experiments.
Testing for EGARCH Against Stochastic Volatility Models
Authors: Kobayashi Masahito , Shi Xiuhong
Published: January 2005

Abstract. It is shown that the EGARCH model is the degenerate case of Danielsson's [Journal of Econometrics(1994) Vol. 61, pp. 375–400] stochastic volatility model where the disturbance of the transition equation of conditional volatility has zero variance. The Lagrange multiplier test statistic is obtained for the EGARCH model against the stochastic volatility model by expressing the degenerate density under the null hypothesis by the Dirac delta function. The finite sample performance of the test is studied in a small Monte Carlo experiment.
Clinical effects of scaling and root planing on untreated teeth
Authors: Pawlowski Adrian P. , Chen Allen , Hacker Beth M. , Mancl Lloyd A. , Page Roy C. , Roberts Frank A.
Published: January 2005

Objective: The aim of this report is to examine whether scaling and root planing (SRP) in one area of the mouth may affect periodontal improvement in untreated areas in the same patient, possibly through systemic effects of treatment.

Material and Methods: Twenty patients diagnosed with generalized aggressive periodontitis were randomized into treatment (n=11) and no treatment (n=9) groups. Within the treatment group, three quadrants were treated by SRP at week 0, 3, 12, and 24, while a single experimental quadrant remained untreated throughout the study. The outcome for all teeth was assessed using clinical parameters, subtraction radiography, and pathogenic bacteria levels in the subgingival flora over the 24‐week study period.

Results: Compared with sites in no treatment patients, the treated sites in the treated patients showed a 1 mm decrease in probing depth (PD) (p<0.01) and a 0.5 mm increase in bone height (p<0.01) by 24 weeks. In untreated sites within treated subjects, however, PDs tended to improve (p=0.09) but at a reduced rate compared with treated sites. The levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis (Bacteroides forsythus) remained unchanged in untreated sites while levels of Prevetolla intermedia and Treponema denticola tended to decrease as compared with controls but did not reach significance.

Conclusions: This study indicates that untreated sites in treated periodontitis patients show a trend towards clinical improvement and exhibit reductions in some but not all periodontopathic bacterial species tested.
Periodontitis, a marker of risk in pregnancy for preterm birth
Authors: Dörtbudak Orhun , Eberhardt Rita , Ulm Martin , Persson G. Rutger
Published: January 2005

Background: Why chronic periodontitis may induce an inflammatory response with premature pregnancy termination is unclear.

Aims: (1) To assess if periodontitis predicts premature gestation; (2) to study amniotic fluid cytokines and periodontitis variables in early‐stage pregnancy.

Material and Methods: A periodontal examination and collection of amniotic fluid was performed (weeks 15–20) of pregnancy in 36 women at risk for pregnancy complications. Amniotic fluid (bacteria), vaginal smears and intra‐oral plaque samples were studied. Cytokine levels in amniotic fluid were studied in relation to other study variables.

Results: Periodontitis was diagnosed in 20% of normal and in 83% of preterm birth cases (p<0.01). Bacteria were never found in the amniotic fluids studied. Sub‐gingival plaque samples including bacteria in the orange and red complexes were found in 18% of full‐term 100% of preterm cases (p<0.001) and total colony‐forming units (CFUs) were higher in preterm birth (p<0.01). Amniotic levels of interleukin (IL)‐6 and prostaglandin‐E2 (PGE2) were higher in preterm cases (p<0.001). Amniotic IL‐6 (r=0.56, p<0.01) and PGE2 (r=0.50, p<0.01) cytokine levels were correlated with CFU from sub‐gingival plaque samples (r2=0.44).The odds ratio of preterm delivery and having periodontitis was 20.0 (95% confidence interval (CI): 2.0–201.7, p<0.01). The odds of >60 CFU in sub‐gingival plaque and preterm birth was 32.5:1 (95% CI: 3.0–335.1, p<01).

Conclusions: Pregnant women with findings of elevated amniotic fluid levels of PGE2, IL‐6 and IL‐8 in the 15–20 weeks of pregnancy and with periodontitis are at high risk for premature birth. The implication of this is that periodontitis can induce a primary host response in the chorioamnion leading to preterm birth.
Periodontal repair in dogs: guided tissue regeneration enhances bone formation in sites implanted with a coral‐derived calcium carbonate biomaterial
Authors: Koo Ki‐Tae , Polimeni Giuseppe , Qahash Mohammed , Kim Chong Kwan , Wikesjö Ulf ME
Published: January 2005

Background: Previous studies suggest that a bioresorbable calcium carbonate coral implant (CI) supports space provision and bone formation for guided tissue regeneration (GTR). However, it could not be discerned whether observed effects were because of GTR or whether the CI possessed osteoconductive properties enhancing bone formation. The objective of this study was to evaluate bone formation associated with the CI biomaterial in the presence and absence of provisions for GTR.

Methods: Routine, critical size, 6 mm, supra‐alveolar periodontal defects were created in 12 young adult Beagle dogs. Five animals received the CI alone (Biocoral® 1000). Seven animals received the CI/GTR combination using an expanded polytetrafluoroethylene barrier (GORE‐TEX® Regenerative Material). The animals were euthanized at 4 weeks postsurgery and tissue blocks of the experimental sites were collected and processed for histometric analysis.

Results: Clinical healing was uneventful. The histopathologic and histometric analysis revealed significantly increased bone formation (height and area) in sites receiving the CI/GTR combination compared with CI alone (2.3±0.6 versus 1.2±0.9 mm; and 3.1±0.8 versus 1.2±1.1 mm2; p<0.05). The CI biomaterial appeared to be mostly unassociated with new bone formation; the CI particles were observed sequestered in newly formed bone, fibrovascular marrow, and in the supra‐alveolar connective tissue. Cementum formation was limited and observed in few sites for both treatment protocols.

Conclusion: While GTR promoted new bone formation, the CI contributed limited, if any, osteoconductive effects.
Evaluation of the relationship between smoking during pregnancy and subgingival microbiota
Authors: Buduneli Nurcan , Baylas Haluk , Buduneli Eralp , Türkoğlu Oya , Dahlen Gunnar
Published: January 2005

Background: Numerous studies have shown that smoking negatively affects periodontal health. Hormonal changes, which occur during pregnancy have also been reported to have adverse effects on the periodontal tissues or indirectly through alterations in the subgingival bacterial flora. At present, no knowledge exists concerning possible effects of smoking on the composition of subgingival plaque in pregnancy. The purpose of the present study was to evaluate the effects of smoking during pregnancy on the subgingival plaque bacteria most commonly associated with periodontal disease.

Methods: A total number of 181 women were examined within 72 h post‐partum. Smoking status was recorded by means of a self‐reported questionnaire and the study population was divided into three groups; non‐smokers, light smokers, and heavy smokers. In each woman, two subgingival plaque samples were obtained from mesio‐ or disto‐buccal aspect of randomly selected one molar and one incisor tooth by sterile paperpoints. Clinical periodontal recordings comprising presence of dental plaque, bleeding on probing (BOP), and probing pocket depth (PPD) were performed at six sites per each tooth at all teeth. Plaque samples were analysed by checkerboard DNA–DNA hybridization with respect to 12 bacterial species. In all analyses, the individual subject was the computational unit. Thus, mean values for all clinical parameters were calculated and bacterial scores from each individual sample were averaged. Statistical methods included χ2 test, Kruskal–Wallis test and Mann–Whitney U‐test.

Results: Mean ages were similar in the study groups. Plaque, BOP and PPD recordings were lower in the heavy‐smoker group, but the differences were not statistically significant (p>0.05). The detection rates and bacterial loads of the specific subgingival bacteria exhibited no significant differences between the groups. No correlation could be found between smoking status and detection rates and bacterial loads of various bacterial species.

Conclusion: The present findings suggest that smoking during pregnancy does not have a significant effect on the composition of subgingival plaque bacteria.
Total fluoride intake in children aged 22–35 months in four Colombian cities
Authors: Franco Ángela M. , Martignon Stefanía , Saldarriaga Alexandra , González María C. , Arbeláez María I. , Ocampo Alvaro , Luna Luz M. , Martínez‐Mier E. Angeles , Villa Alberto E.
Published: January 2005

Abstract –  Objective: To obtain information on the level of total fluoride intake from food, beverages and toothpaste by children at the age of 22–25 months of low and high socioeconomic status (SES) in major Colombian cities.

Methods:  Daily fluoride intake was assessed by the duplicate plate method and by recovered toothpaste solution during a 3‐day period and afterwards analysed by the microdiffusion method.

Results:  Mean daily fluoride intake was 0.11 (±0.10), 0.14 (±0.12), 0.10 (±0.07) and 0.07 (±0.06) mg/kg body weight (bw)/day in Bogotá, Medellín, Manizales and Cartagena, respectively. The total fluoride intake was higher in low‐SES subjects in the cities of Medellín and Bogotá. In the high‐SES children of the four cities, the average intakes ranged from 0.06 to 0.09 mg F/kg bw, whereas, the low‐SES children in three cities had intakes between 0.11 and 0.21 mg F/kg bw (Cartagena, 0.07). Toothpaste (containing 1000–1500 ppm F, with 1500 ppm F being more common) accounted for approximately 70% of total fluoride intake, followed by food (24%) and beverages (<6%). More than half the children had their teeth brushed by an adult, on average twice a day, using 0.22–0.65 g of toothpaste.

Conclusion:  Children from three Colombian cities have a mean total daily fluoride intake above the ‘optimal range’. Health authorities should promote an appropriate use of fluoridated dentifrices discouraging the use of dentifrices containing 1500 ppm F in children younger than 6 years of age and promoting a campaign of education of parents and oral health professionals on adequate toothbrushing practices.
Relationships between lifestyle and dental health behaviors in a rural population in Japan
Authors: Harada Shoji , Akhter Rahena , Kurita Keiko , Mori Miyako , Hoshikoshi Misuzu , Tamashiro Hidehiko , Morita Manabu
Published: January 2005

Abstract –  Objectives:  The aim of this study was to determine associations of lifestyle with dental health behaviors such as tooth brushing frequency, use of extra cleaning devices, and regular dental visits to a dentist.

Methods:  Data were collected from 1182 dentate residents 18 years of age or older who resided in a typical farming district. The data included data on the demographic factors, dental health behavior, and various aspects of lifestyle, i.e. mental condition, alcohol consumption, smoking habit, physical activity, social activity, dietary habits, and presence of systemic diseases.

Results:  Multiple logistic regression analysis revealed that subjects in a younger group (18–39 years of age) and subjects who had never smoked brushed their teeth more frequently. Experience of social volunteer work and presence of systemic disease were correlated with use of extra cleaning devices. Associations of female gender with frequency of tooth brushing and use of extra cleaning devices were weakly positive. The subjects who considered dietary combination carefully and those who lived alone were predisposed to visit a dentist regularly.

Conclusions:  The results indicate that dental health behavior is associated with lifestyle as well as demographic factors.
Risk indicators for oral candidiasis and oral hairy leukoplakia in HIV‐infected adults
Authors: Chattopadhyay Amit , Caplan Daniel J. , Slade Gary D. , Shugars Diane C. , Tien Hsaio‐Chuan , Patton Lauren L.
Published: January 2005

Abstract –  Objectives:  Oral candidiasis (OC) and oral hairy leukoplakia (OHL) are the most common oral mucosal diseases associated with HIV infection. Independent risk indicators associated with these sentinel opportunistic diseases have not been established in mixed race and gender adult populations in the southeast USA. The purposes of this study were 1) to estimate prevalence of OC and OHL among an HIV‐1 positive adult population, and 2) to develop explanatory multivariable models for each disease outcome.

Methods:  This cross‐sectional study evaluated 631 adult dentate HIV‐1 seropositive persons examined for HIV‐associated oral mucosal diseases between 1995 and 2000 at University of North Carolina Hospitals in Chapel Hill, North Carolina using data collected from medical record review, interview questionnaire and clinical examination. We analyzed the data using t‐tests, anova, and unconditional logistic regression.

Results:  Prevalent OC was associated with low CD4+ cell count [<200 cells/μl, adj. OR=12.7 (95%CI: 4.9–32.9)], antiretroviral combination therapy [OR=0.6 (0.3–0.9)], and current smoking [OR=2.5 (1.3–4.8)]. Prevalent OHL was associated with low CD4+ cell count [<200 cells/μl, OR=7.2 (2.7–18.9)], antifungal medication use [OR=1.8 (1.1–2.9)], current recreational drug use [OR=2.5 (1.3–4.9)], and male gender [OR=2.5 (1.3–4.8)].

Conclusions:  While CD4+ cell count, and antiretroviral medication were important risk indicators for OC, and OHL, cigarette smoking appears to be an important risk indicator for OC in HIV‐1‐infected populations.
Effect of augmented visual feedback from a virtual reality simulation system on manual dexterity training
Authors: Wierinck E. , Puttemans V. , Swinnen S. , van Steenberghe D.
Published: January 2005

Little research has been published about the impact of simulation technology on the learning process of novel motor skills. Especially the role of augmented feedback (FB) on the quality of performance and the transfer of the acquired behaviour to a no‐augmented FB condition require further investigation. Therefore, novice dental students were randomly assigned to one of three groups and given the task of drilling a geometrical class 1 cavity. The FB group trained under augmented visual FB conditions, provided by the virtual reality (VR) system (DentSimTM). The no‐FB group practised under normal vision conditions, in the absence of augmented FB. A control group performed the test sessions without participating in any training programme. All preparations were evaluated by the VR grading system according to four traditional (outline shape, floor depth, floor smoothness and wall inclination), and two critical, criteria (pulp exposure and damage to adjacent teeth). Performance analyses revealed an overall trend towards significant improvement with training for the experimental groups. The FB group obtained the highest scores. It scored better for floor depth (P < 0.001), whilst the no‐FB group was best for floor smoothness (P < 0.005). However, at the retention tests, the FB group demonstrated inferior performance in comparison with the no‐FB group. The transfer test on a traditional unit revealed no significant differences between the training groups. Consequently, drilling experience on a VR system under the condition of frequently provided FB and lack of any tutorial input was considered to be not beneficial to learning. The present data are discussed in view of the guidance hypothesis of FB, which refers to the apprentice's dependence on FB.
A comparative evaluation of computer literacy amongst dental educators and students
Authors: Mattheos N. , Schittek M. Janda , Nattestad A. , Shanley D. , Attström R.
Published: January 2005

A task‐oriented questionnaire was designed, aiming to quickly assess competence with the use of computers. The questionnaire consisted of distinct computer‐related skills, representing various competences in educational computer use. A total score from 0 to 49 was calculated upon completion of the questionnaire, based on the sum of all the positively identified competences. The questionnaire was distributed to an international group of leading dental educators during the DentEd Global Congress in Prague in 2001 and to a cohort of first year dental students (2001) in the Dental Faculty, University of Malmö, Sweden. Certain attitudes towards the role of information and communication technology (ICT) in dental education were also measured through Visual Analogue Scales in the educator's group. A total of 149 questionnaires were collected from the educators’ group and 58 from the dental students. There was no significant difference in the average computer competence score between the two groups. The educators’ group average score was 20.7 (SD 9.9) and students’ average was 18.1 (SD 8.5). A significant positive correlation (r = 0.395277, P < 0.0001) was found between the competence measured by the questionnaire and the year of graduation in the educators’ group. The attitudes towards the role of ICT in dental education amongst the educators were very positive, regardless of their competence with computers, year of graduation or academic position. The results from this study indicate that there is wide diversity in computer competence amongst both students and academic staff. In addition, students’ actual competence in the use of computers might not be as high as is often perceived through self‐assessment and ordinal scales.
Learning from the Past to Change Our Future
Authors: Flannery Tim
Published: January 2005

Collapse
How Societies Choose to Fail or Succeed.
By Jared Diamond
. Viking Press, New York, 2005. 591 pp. $29.95, C$44. ISBN 0-670-03337-5.

Examining cases such as Easter Island, the Greenland Norse, and the Classic Maya, the author provides a comparative study of the economic and social ruin that occurs when societies undermine their ecological foundations.
A computational model of mitochondrial deoxynucleotide metabolism and DNA replication
Authors: Bradshaw Patrick C. , Samuels David C.
Published: January 2005

We present a computational model of mitochondrial deoxynucleotide metabolism and mitochondrial DNA (mtDNA) synthesis. The model includes the transport of deoxynucleosides and deoxynucleotides into the mitochondrial matrix space, as well as their phosphorylation and polymerization into mtDNA. Different simulated cell types (cancer, rapidly dividing, slowly dividing, and postmitotic cells) are represented in this model by different cytoplasmic deoxynucleotide concentrations. We calculated the changes in deoxynucleotide concentrations within the mitochondrion during the course of a mtDNA replication event and the time required for mtDNA replication in the different cell types. On the basis of the model, we define three steady states of mitochondrial deoxynucleotide metabolism: the phosphorylating state (the net import of deoxynucleosides and export of phosphorylated deoxynucleotides), the desphosphorylating state (the reverse of the phosphorylating state), and the efficient state (the net import of both deoxynucleosides and deoxynucleotides). We present five testable hypotheses based on this simulation. First, the deoxynucleotide pools within a mitochondrion are sufficient to support only a small fraction of even a single mtDNA replication event. Second, the mtDNA replication time in postmitotic cells is much longer than that in rapidly dividing cells. Third, mitochondria in dividing cells are net sinks of cytoplasmic deoxynucleotides, while mitochondria in postmitotic cells are net sources. Fourth, the deoxynucleotide carrier exerts the most control over the mtDNA replication rate in rapidly dividing cells, but in postmitotic cells, the NDPK and TK2 enzymes have the most control. Fifth, following from the previous hypothesis, rapidly dividing cells derive almost all of their mtDNA precursors from the cytoplasmic deoxynucleotides, not from phosphorylation within the mitochondrion.
Innate Immunity and Angiogenesis
Authors: Frantz Stefan , Vincent Karen A. , Feron Olivier , Kelly Ralph A.
Published: January 2005

Activation of an innate immune response is among the first lines of defense after tissue injury. Restoring blood flow to the site of injured tissue is often a necessary prerequisite for mounting an initial immune response to pathogens and for subsequent initiation of a successful repair of wounded tissue. The multiple links among pathogen recognition and suppression, increased angiogenesis, and tissue repair are the topics of this review, which examines of the roles of antimicrobial peptides, mammalian toll-like receptors (TLRs), inflammatory cytokines, and putative “danger” signals, among other signaling pathways, in triggering, sustaining, and then terminating an angiogenic response.
'Modernising Conservatism' in Early Twentieth-Century China: the Discourse and Practice of Women's Education
Authors: Bailey Paul
Published: January 2005

This paper focuses on a pervasive strand of thinking on women's public education during the last years of the Qing and early years of the Republic which sought to reconfigure traditional virtues and skills in the cause of family harmony, social order and national prosperity. A study of this 'modernising conservative' discourse on women's education and its critique of the behaviour and attitudes of female students also provides an insight into how female students themselves responded to the new educational opportunities available to them.
Leveled Mountains and Broken Fences: Measuring and Analysing De Facto Decentralisation in Vietnam
Authors: Malesky Edmund
Published: January 2005

The article seeks to measure and explain provincial autonomy in Vietnam during the reform era, arguing that the absence of an effective measure of autonomy to date has limited the scope for developing an overarching theory capable of explaining autonomy across a range of settings. The article pioneers a method for measuring autonomy involving a content analysis of Vietnamese newspapers over a ten-year period, noting whenever provinces are reported for engaging in a series of carefully defined autonomous acts. Having developed the measure of autonomy, the article seeks to test four hypotheses for explaining it, namely geographical location, relations with central government, initial conditions on the eve of reform, and the dominant source of economic activity in terms of ownership. The article finds that no single factor accounts for autonomy on its own but also that there is only a weak relationship between autonomy and a province's geographical location and that provinces heavily represented in central government tend to be among the least autonomous.
Flux Replacement as a Method to Diagnose Coupled Land–Atmosphere Model Feedback
Authors: Dirmeyer Paul A. , Zhao Mei
Published: January 2005

The potential role of the land surface state in improving predictions of seasonal climate is investigated with a coupled land–atmosphere climate model. Climate simulations for 18 boreal-summer seasons (1982–99) have been conducted with specified observed sea surface temperature (SST). The impact on prediction skill of the initial land surface state (interannually varying versus climatological soil wetness) and the effect of errors in downward surface fluxes (precipitation and longwave/shortwave radiation) over land are investigated with a number of parallel experiments. Flux errors are addressed by replacing the downward fluxes with observed values in various combinations to ascertain the separate roles of water and energy flux errors on land surface state variables, upward water and energy fluxes from the land surface, and the important climate variables of precipitation and near-surface air temperature.

Large systematic errors are found in the model, which are only mildly alleviated by the specification of realistic initial soil wetness. The model shows little skill in simulating seasonal anomalies of precipitation, but it does have skill in simulating temperature variations. Replacement of the downward surface fluxes has a clear positive impact on systematic errors, suggesting that the land–atmosphere feedback is helping to exacerbate climate drift. Improvement in the simulation of year-to-year variations in climate is even more evident. With flux replacement, the climate model simulates temperature anomalies with considerable skill over nearly all land areas, and a large fraction of the globe shows significant skill in the simulation of precipitation anomalies. This suggests that the land surface can communicate climate anomalies back to the atmosphere, given proper meteorological forcing. Flux substitution appears to have the largest benefit to improving precipitation skill over the Northern Hemisphere midlatitudes, whereas use of realistic land surface initial conditions improves skill to significant levels over regions of the Southern Hemisphere. Correlations between sets of integrations show that the model has a robust and systematic global response to SST anomalies.
Incorporating Hydraulic Lift into a Land Surface Model and Its Effects on Surface Soil Moisture Prediction
Authors: Ren Diandong , Xue Ming , Henderson-Sellers Ann
Published: January 2005

In comparison with the Oklahoma Atmospheric Surface-layer Instrumentation System (OASIS) measurements, the Simulator for Hydrology and Energy Exchange at the Land Surface (SHEELS), a multilayer soil hydrological model, simulates a much faster drying of the superficial soil layer (5 cm) for a densely vegetated area at the OASIS site in Norman, Oklahoma, under dry conditions. Further, the measured superficial soil moisture contents also show a counterintuitive daily cycle that moistens the soil during daytime and dries the soil at night. The original SHEELS model fails to simulate this behavior. This work proposes a treatment of hydraulic lift processes associated with stressed vegetation and shows via numerical experiments that both problems reported above can be much alleviated by including the hydraulic lift effect associated with stressed vegetation.
Optimized Surface Radiation Fields Derived from Meteosat Imagery and a Regional Atmospheric Model
Authors: Meetschen Dirk , van den Hurk Bart J. J. M. , Ament Felix , Drusch Matthias
Published: January 2005

High-quality fields of surface radiation fluxes are required for the development of Land Data Assimilation Systems. A fast offline integration scheme was developed to modify NWP model cloud fields based on Meteosat visible and infrared observations. From the updated cloud fields, downward shortwave and longwave radiation at the surface are computed using the NWP radiative transfer model.

A dataset of 15 months covering Europe was produced and validated against measurements of ground stations on a daily basis. In situ measurements are available for 30 stations in the Netherlands and two Baseline Surface Radiation Network (BSRN) stations in Germany and France. The accuracy of shortwave surface radiation is increased when the integration system is applied. The rms error in the model forecast is found to be 32 and 42 W m−2 for the period from October 1999 to December 2000 for the two BSRN stations. These values are reduced to 21 and 25 W m−2 through the application of the integration scheme. During the summer months the errors are generally larger than in winter. Because of an integrated monitoring of surface albedo, the performance of the scheme is not affected by snow cover. The errors in the longwave radiation field of the original NWP model are already small. However, they are slightly reduced by applying the integration scheme.
Effects of Spatial and Temporal Aggregation on the Accuracy of Statistically Downscaled Precipitation Estimates in the Upper Colorado River Basin
Authors: Gangopadhyay Subhrendu , Clark Martyn , Werner Kevin , Brandon David , Rajagopalan Balaji
Published: January 2005

To test the accuracy of statistically downscaled precipitation estimates from numerical weather prediction models, a set of experiments to study what space and time scales are appropriate to obtain downscaled precipitation forecasts with maximum skill have been carried out. Fourteen-day forecasts from the 1998 version of the National Centers for Environmental Prediction (NCEP) Medium-Range Forecast (MRF) model were used in this study. It has been previously found that downscaled temperature fields have significant skill even up to 5 days of forecast lead time, but there is practically no valuable skill in the downscaled precipitation forecasts. Low skill in precipitation forecasts revolves around two main issues. First, the (intermittent) precipitation variability on daily and subdaily time scales could be too noisy to derive meaningful relationships with atmospheric predictors. Second, the model parameterizations and the coarse spatial resolution of the current generation of global-scale forecast models might be unable to resolve the local-scale variability in precipitation. Both of these issues may be addressed by spatial and temporal averaging.

In this paper the authors present a diagnostic study using a set of numerical experiments to understand how spatial and temporal aggregations affect the skill of downscaled precipitation forecasts in the upper Colorado River basin. The question addressed is, if the same set of predictor variables from numerical weather prediction models is used, what space (e.g., station versus regional average) and time (e.g., subdaily versus daily) scales optimize regression-based downscaling models so as to maximize forecast skill for precipitation? Results in general show that spatial and temporal averaging increased the skill of downscaled precipitation estimates. At subdaily (6 hourly) and daily time scales, the skill of downscaled estimates at spatial scales greater than 50 km was generally higher than the skill of downscaled estimates at individual stations. For the 6-hourly time scale both for stations and for mean areal precipitation estimates the maximum forecast skill was found to be approximately half that of the daily time scale. At forecast lead times of 5 days, when there is very little skill at daily and subdaily time scales, useful skill emerged when station data are aggregated to 3- and 5-day averages.
The Effect of Perceived Learner Advantages on Teachers' Beliefs About Critical-Thinking Activities
Authors: Warburton Edward , Torff Bruce
Published: January 2005

To investigate teachers' beliefs about critical-thinking (CT) activities for different populations of learners, the Critical Thinking Belief Appraisal (CTBA) was administered to 145 practicing secondary teachers. Teachers rated both high-CT and low-CT activities as more effective for highadvantage learners than low-advantage ones, demonstrating strong “advantage effects.” They also rated high-CT activities as more effective than low-CT ones for both high-advantage and lowadvantage learners, demonstrating “pedagogical-preference effects” stronger for high-advantage learners than low-advantage ones. Although these results are inconsistent with the assertion that teachers favor low-CT activities over high-CT ones for low-advantage learners, the results suggest that low-advantage learners may receive fewer high-CT activities in schools, which may hinder their academic performance. Studies of the development of teachers' CT-related beliefs are needed, with the goal of establishing teacher-education practices emphasizing appropriate use of high-CT activities for low-advantage learners.
Preservice Teachers Becoming Agents of Change
Authors: Price Jeremy N. , Valli Linda
Published: January 2005

This article examines the construction and experience of change agency within action research courses in preservice teacher education. Four preservice teachers' experiences of action research are analyzed, and tensions and challenges teacher educators and preservice teachers face as they attend to change processes in learning to teach are explored. This analysis suggests five central tensions in the process and pedagogy of action research: individual and institutional change, action and understanding, support and challenge, passion and reason, and regulation and emancipation. Rather than selecting one side of a tension over another, the authors argue that teacher educators need to work with tensions to develop understandings of change in relation to biography, teaching, and context. The authors argue that such contradictory and complex dimensions provide a useful frame for a pedagogy of action research. They are integral to the process of helping teacher candidates develop conceptions of teaching that embody change agency.
Addressing Teacher Quality Through Induction, Professional Compensation, and Evaluation: The Effects on Labor-Management Relations
Authors: Koppich Julia
Published: January 2005

Conventional wisdom has it that teacher unions are singularly concerned with enhancing the compensation packages of those whom they represent. Issues central to educational quality, from better teacher preparation to more rigorous professional evaluation, play second fiddle to the primary union focus on wages and benefits, according to conventional wisdom. However, the notion that teacher unions are interested only in improving salary levels belies an emerging truth in some school district-union partnerships. In the locales that are the subject of this article, union and management are creating a new text about labor-management relations. Minneapolis’s Achievement of Tenure process, Denver’s Professional Compensation system, and Montgomery County, Maryland’s Professional Growth System reflect very different kinds of labor-management agreements than are the usual subject of discourse and critique. In these places, labor-management agreements form the foundation of programs designed to improve the quality of teaching and levels of student learning.
Hardiness, Job Satisfaction, and Stress Among Home Health Nurses
Authors: Judkins Sharon , Rind Raedel
Published: January 2005

This descriptive study examines the relationship between hardiness, job satisfaction, and stress among home health nurses. Results of the study indicate that nurses with high levels of hardiness tend to have lower stress and higher levels of job satisfaction. Implications for home health managers and administrators include providing a high-hardy environment to improve retention and to decrease staff turnover.