bluuebunny/crossref_metadata_2025 huggingface dataset:
Components of tree resilience: effects of successive low‐growth episodes in old ponderosa pine forests
Authors: Lloret Francisco , Keeling Eric G. , Sala Anna
Published: July 2011

Recent world‐wide episodes of tree dieback have been attributed to increasing temperatures and associated drought. Because these events are likely to become more common, improved knowledge of their cumulative effects on resilience and the ability to recover pre‐disturbance conditions is important for forest management. Here we propose several indices to examine components of individual tree resilience based on tree ring growth: resistance (inverse of growth reduction during the episode), recovery (growth increase relative to the minimum growth during the episode), resilience (capacity to reach pre‐episode growth levels) and relative resilience (resilience weighted by the damage incurred during the episode).

Based on tree ring analyses, we analyzed historical patterns of tree resilience to successive drought‐induced low growth periods in ponderosa pine trees growing in unmanaged, remote forests of the Rocky Mountains. Low‐growth periods registered in tree rings were related to anomalies in the Palmer drought severity index (PDSI) and were attributed to drought.

Independently of the impact of a specific event, subsequent growth after a single low‐growth episode was related to the growth prior to the event. Growth performance differed with tree age: young trees were overall more resistant to low‐growth periods, but older trees recovered better from more recent events. Regardless of tree age, recently burned sites exhibited lower post‐episode growth and lower resistance and resilience than unburned ones. We found mixed evidence for the cumulative effect of past low‐growth episodes: overall, greater impacts of a prior event and greater cumulative effects of past low‐growth periods caused a decrease in resistance. However, we did not find a progressive decrease in resilience over time in old trees.

Our results highlight the value of using a combination of estimators to evaluate the different components of resilience. Specifically, while tree responses to disturbance depend on past disturbance episodes, the response is context‐specific and depends on the impact the capacity to recover after disturbance. This suggests that recent increases in forest mortality under current climate trends could relate to thresholds on specific components of resilience (resistance, recovery, resilience itself) rather than to an overall loss of resilience over time. Identifying such thresholds and their underlying mechanisms is a promising area of research with important implications for forest management.
Stochastic LTRE analysis of the effects of herbivory on the population dynamics of a perennial grassland herb
Authors: Jacquemyn Hans , Brys Rein , Davison Raziel , Tuljapurkar Shripad , Jongejans Eelke
Published: July 2011

Herbivores can have strong deleterious effects on vital rates (growth, reproduction, and survival) and thus negatively impact the population dynamics of plant species. In practice, however, these effects might be strongly correlated, for example as a result of tradeoffs between vital rates. To get better insights into the effects of herbivory on the population dynamics of the long‐lived grassland plant Primula veris population projection matrices were constructed from demographic data collected between 1999 and 2008 (nine annual transitions). Data were collected in two large grassland populations, each of which was subjected to two treatments (grazing by cattle versus a mowing treatment), yielding a total of 36 matrices. We applied a lower‐level vital rate life table response experiment (LTRE) using the small noise approximation (SNA) of the stochastic population growth rate to disentangle the contributions of changes in mean vital rates, variability in vital rates, correlations between vital rates and vital rate elasticities to the difference in the stochastic growth rate. Stochastic growth rates (a= log λS) were significantly lower in grazed than in mown plots (a= 0.0185 and 0.1019, respectively). SNA LTRE analysis showed that contributions of mean vital rates by far made the largest contribution to the observed difference in a between grazed and control plots. In particular, changes in sexual reproduction rates made the largest contributions to lower the stochastic growth rate in grazed plots: both adult flowering probabilities and flower and seed production were importantly lower in grazed populations, but these negative effects were largely buffered by increased establishment and seedling survival rates. Among the stochastic terms of the SNA decomposition, contributions of covariance and correlations between vital rates had the largest impact, whereas contributions of elasticities were smaller. The strongest correlation driver was the association between adult survival and seedling establishment, suggesting that environmental conditions favouring adult survival also are beneficial for seedling establishment. Overall, our results show that herbivory had a strong negative effect on the long‐term population growth rate of P. veris that was primarily mediated by differences in fecundity (flower and seed production) and germination.
Why Iranian adolescents do not brush their teeth: a qualitative study
Authors: Pakpour AH , Hidarnia A , Hajizadeh E , Kumar S , Fridlund B
Published: July 2011

To cite this article:
 
Int J Dent Hygiene 10, 2012; 86–90  DOI: 10.1111/j.1601‐5037.2011.00513.x

Pakpour AH, Hidarnia A, Hajizadeh E, Kumar S, Fridlund B. Why Iranian adolescents do not brush their teeth: a qualitative study.

Objectives:  To explore and describe attitudes towards tooth‐brushing among Iranian adolescents.

Methods:  A series of focus‐group sessions were held with 37 Iranian adolescents in schools. The groups comprised five to eight adolescents. All focus‐group discussions were tape‐recorded and then transcribed verbatim. All transcripts, codes and categories were read several times to extract a theme. Data were analysed using a qualitative content analysis approach.

Results:  Four major categories emerged from the analysis: brushing teeth is a necessary evil, parental influence on not brushing teeth, brushing teeth is insignificant, and brushing teeth is a health hazard. The theme identified in the latent content described that tooth‐brushing is not part of the adolescents’ activities of daily living.

Conclusions:  Health educators should stress on the engagement of parents, awareness of the adolescents on brushing techniques and causes of toothache, and address any misconceptions regarding tooth‐brushing.
IMAGING ASSESSMENT OF THE MODIFIED DOUBLE CONTRAST BARIUM ENEMA USING CARBOXYMETHYLCELLULOSE ON RADIOGRAPHY AND ULTRASONOGRAPHY IN DOGS
Authors: CHOI MIHYUN , LEE NAMSOON , KIM JUNYOUNG , YI KANGJAE , JUNG JOOHYUN , YOON JUNGHEE , CHOI MINCHEOL
Published: July 2011

A modified double contrast barium enema using carboxymethylcellulose was evaluated in beagle dogs and compared with dogs receiving a conventional barium enema. The experimental group was divided into three groups (1, 2, and 3) and given 30 ml/kg of different volume ratios of a barium vs. carboxymethylcellulose mixture. Each group underwent sonography following radiography. The volume ratio of one part barium to three parts carboxymethylcellulose was judged to be the optimal mixture, resulting in a general distribution of contrast and bowel radiolucency on radiographs and adequate postradiography sonography. The modified barium enema using carboxymethylcellulose is useful for assessing the general morphology and mucosal layers of the colon simultaneously on radiographs and ultrasonographs.
Effect of the N‐terminal sequence on the binding affinity of transthyretin for human retinol‐binding protein
Authors: Leelawatwattana Ladda , Praphanphoj Verayuth , Prapunpoj Porntip
Published: July 2011

During vertebrate evolution, the N‐terminal region of transthyretin (TTR) subunit has undergone a change in both length and hydropathy. This was previously shown to change the binding affinity for thyroid hormones (THs). However, it was not known whether this change affects other functions of TTR. In the present study, the effect of these changes on the binding of TTR to retinol‐binding protein (RBP) was determined. Two wild‐type TTRs from human and Crocodylus porosus, and three chimeric TTRs, including a human chimeric TTR in which its N‐terminal sequence was changed to that of C. porosus TTR (croc/huTTR) and two C. porosus chimeric TTRs (hu/crocTTR in which its N‐terminal sequence was changed to that of human TTR and xeno/crocTTR in which its N‐terminal sequence was changed to that of Xenopus laevis TTR), were analyzed for their binding to human RBP by native‐PAGE followed by immunoblotting and a chemilluminescence assay. The Kd of human TTR was 30.41 ± 2.03 μm, and was similar to that reported for the second binding site, whereas that of crocodile TTR was 2.19 ± 0.24 μm. The binding affinities increased in croc/huTTR (Kd = 23.57 ± 3.54 μm) and xeno/crocTTR (Kd = 0.61 ± 0.16 μm) in which their N‐termini were longer and more hydrophobic, but decreased in hu/crocTTR (Kd = 5.03 ± 0.68 μm) in which its N‐terminal region was shorter and less hydrophobic. These results suggest an influence of the N‐terminal primary structure of TTR on its function as a co‐carrier for retinol with RBP.

Structured digital abstract

 RBP and TTR bind by blue native page (View interaction)

RBP
 and TTR bind by blue native page (View interaction)

RBP
 binds to TTR by surface plasmon resonance (View interaction)

TTR
 binds to TTR by blue native page (View interaction)

TTR
 binds to TTR by blue native page (View interaction)
Calcium‐regulated conformational change in the C‐terminal end segment of troponin I and its binding to tropomyosin
Authors: Zhang Zhiling , Akhter Shirin , Mottl Steven , Jin Jian‐Ping
Published: July 2011

The troponin complex plays an essential role in the thin filament regulation of striated muscle contraction. Of the three subunits of troponin, troponin I (TnI) is the actomyosin ATPase inhibitory subunit and its effect is released upon Ca2+ binding to troponin C. The exon‐8‐encoded C‐terminal end segment represented by the last 24 amino acids of cardiac TnI is highly conserved and is critical to the inhibitory function of troponin. Here, we investigated the function and calcium regulation of the C‐terminal end segment of TnI. A TnI model molecule was labeled with Alexa Fluor 532 at a Cys engineered at the C‐terminal end and used to reconstitute the tertiary troponin complex. A Ca2+‐regulated conformational change in the C‐terminus of TnI was shown by a sigmoid‐shape fluorescence intensity titration curve similar to that of the CD calcium titration curve of troponin C. Such corresponding Ca2+ responses are consistent with the function of troponin as a coordinated molecular switch. Reconstituted troponin complex containing a mini‐troponin T lacking its two tropomyosin‐binding sites showed a saturable binding to tropomyosin at pCa 9 but not at pCa 4. This Ca2+‐regulated binding was diminished when the C‐terminal 19 amino acids of cardiac TnI were removed. These results provided novel evidence for suggesting that the C‐terminal end segment of TnI participates in the Ca2+ regulation of muscle thin filament through interaction with tropomyosin.

Structured digital abstract

 McTnT binds to Tropomyosin by enzyme linked immunosorbent assay (View interaction)

 McTnI binds to TnC by enzyme linked immunosorbent assay (View interaction)

 Tropomyosin physically interacts with McTnT and McTnI by enzyme linked immunosorbent assay (View interaction)

 McTnI binds to TnT by enzyme linked immunosorbent assay (View interaction)
Older Adult Who Falls: A Case Study
Authors: McLean Patricia A.
Published: July 2011

PURPOSE.  The purpose of this case study is to illustrate the nursing process by incorporating the standardized nursing languages of NANDA International, the Nursing Interventions Classification, and the Nursing Outcomes Classification to assist an older adult with a history of falls.

DATA SOURCES.  The data sources were the author's clinical nursing practice and research‐based evidence related to falls of older adults.

DATA SYNTHESIS.  The data were synthesized by using clinical reasoning to select the best possible nursing diagnoses, interventions, and patient outcomes.

CONCLUSIONS.  To provide a framework for nurses to achieve positive patient outcomes, standardized nursing languages should be incorporated into patients' clinical nursing databases.

IMPLICATIONS FOR NURSING.  In determining factors that relate to falls, nurses need to obtain baseline data, set goals with patients, and identify milestones, while encouraging patients to be active participants in plans of care.
How neutral is the intergalactic medium surrounding the redshift z = 7.085 quasar ULAS J1120+0641?
Authors: Bolton J. S. , Haehnelt M. G. , Warren S. J. , Hewett P. C. , Mortlock D. J. , Venemans B. P. , McMahon R. G. , Simpson C.
Published: July 2011

The quasar ULAS J1120+0641 at redshift z = 7.085 has a highly ionized near zone which is smaller than those around quasars of similar luminosity at z ≃ 6. The spectrum also exhibits evidence for a damping wing extending redward of the systemic Lyα redshift. We use radiative transfer simulations in a cosmological context to investigate the implications for the ionization state of the inhomogeneous intergalactic medium (IGM) surrounding this quasar. Our simulations show that the transmission profile is consistent with an IGM in the vicinity of the quasar with a volume averaged H i fraction of and that ULAS J1120+0641 has been bright for 106–107 yr. The observed spectrum is also consistent with smaller IGM neutral fractions, , if a damped Lyα system in an otherwise highly ionized IGM lies within 5 proper Mpc of the quasar. This is, however, predicted to occur in only ∼5 per cent of our simulated sightlines for a bright phase of 106–107 yr. Unless ULAS J1120+0641 grows during a previous optically obscured phase, the low age inferred for the quasar adds to the theoretical challenge of forming a 2 × 109 M⊙ black hole at this high redshift.
New exact solutions of magnetic ellipsoidal figures of equilibrium
Authors: Kawamura Takumu , Taniguchi Keisuke , Yoshida Shin’ichirou , Eriguchi Yoshiharu
Published: July 2011

In this Letter we report brand new analytic stationary solutions of constant density stars with magnetic field and self-gravity. These solutions include prolate configurations even for purely poloidal magnetic fields as well as oblate configurations. These new analytic solutions are expressed in very simple forms and can be considered as generalized configurations of uniformly rotating constant density spheroids, i.e. Maclaurin spheroids, and of constant density ellipsoids with constant vorticity, i.e. Dedekind ellipsoids. As the axisymmetric Maclaurin spheroids and the triaxial Dedekind ellipsoids have been widely used for the estimation of the effect of rotations and/or internal motions on the self-gravitating bodies, our new analytic solutions may be used widely to estimate the effect of the magnetic fields semi-quantitatively in various contexts hereafter.
Parent stars of extrasolar planets – XII. Additional evidence for trends with υ sin i, condensation temperature and chromospheric activity
Authors: Gonzalez Guillermo
Published: July 2011

Several recent studies have reported differences in υ sin i, abundance–condensation temperature trends and chromospheric activity between samples of stars with and without Doppler-detected planets. These findings have been disputed, and the status of these results remains uncertain. We evaluate these claims using additional published data and find support for all three.
Bayesian evidence for two companions orbiting HIP 5158
Authors: Feroz F. , Balan S. T. , Hobson M. P.
Published: July 2011

We present results of a Bayesian analysis of radial velocity data for the star HIP 5158, confirming the presence of two companions and also constraining their orbital parameters. Assuming Keplerian orbits, the two-companion model is found to be e48 times more probable than the one-planet model, although the orbital parameters of the second companion are only weakly constrained. The derived orbital periods are 345.6 ± 2.0 and 9017.8 ± 3180.7 d, respectively, and the corresponding eccentricities are 0.54 ± 0.04 and 0.14 ± 0.10. The limits on planetary mass (m sin i) and semimajor axis are (1.44 ± 0.14MJ, 0.89 ± 0.01 au) and (15.04 ± 10.55MJ, 7.70 ± 1.88 au), respectively. Owing to the large uncertainty on the mass of the second companion, we are unable to determine whether it is a planet or a brown dwarf. The remaining ‘noise’ (stellar jitter) unaccounted for by the model is 2.28 ± 0.31 m s−1. We also analysed a three-companion model, but found it to be e8 times less probable than the two-companion model.
The application of GIS and spatiotemporal analyses to investigations of unusual marine mammal strandings and mortality events
Authors: Norman Stephanie A. , Huggins Jessie , Carpenter Tim E. , Case James T. , Lambourn Dyanna M. , Rice Jim , Calambokidis John , Gaydos Joseph K. , Hanson M. Bradley , Duffield Deborah A. , Dubpernell Sandra , Berta Susan , Klope Matt
Published: July 2011

Abstract

In 2006–2007, an unusually high number of harbor porpoises (Phocoena phocoena) stranded along the Washington and Oregon coastlines. Spatiotemporal analyses were used to examine their ability to detect clusters of porpoise strandings during an unusual mortality event (UME) in the Pacific Northwest using stranding location data. Strandings were evaluated as two separate populations, outer coast and inland waters. The presence of global clustering was evaluated using the Knox spatiotemporal test, and the presence of local clusters was investigated using a spatiotemporal scan statistic (space–time permutation). There was evidence of global clustering, but no local clustering, supporting the hypothesis that strandings were due to more varied etiologies instead of localized causes. Further analyses at subregional levels, and concurrently assessing environmental factors, might reveal additional geographic distribution patterns. This article describes the spatial analytical tools applied in this study and how they can help elucidate the spatiotemporal epidemiology of other UMEs and assist in determining their causes. More than one spatial analytical technique should be used if the study objective is to detect and describe clustering in time and space and to generate hypotheses regarding causation of marine mammal disease and stranding events.
Modeling the diet of humpback whales: An approach using stable carbon and nitrogen isotopes in a Bayesian mixing model
Authors: Witteveen Briana H. , Worthy Graham A. J. , Foy Robert J. , Wynne Kate M.
Published: July 2011

Abstract

Humpback whales are considered generalist predators, feeding on schooling fish, and zooplankton, but variability likely exists among regional feeding aggregations. We explored the diet of one feeding aggregation of humpback whales near Kodiak Island, Alaska, through analysis of the stable carbon (δ13C) and nitrogen (δ15N) isotope ratios of their skin and regional prey sources. Humpback whales were sampled during the summer feeding season over 3 yr (n= 93; 2004–2006). Prey samples were collected from the same region during trawl surveys conducted between 2003 and 2005. Isotope values of humpback whale skin and prey were entered into a Bayesian dietary mixing model to estimate feasible contributions of prey to humpback diets. Diet results indicated that humpbacks feed heavily on euphausiids, but also consume juvenile walleye pollock, capelin, and Pacific sand lance. The diet of humpback whales in 2004 was the most diverse, while diets in 2005 and 2006 showed a higher proportion of euphausiids. Our results reveal annual differences in humpback diets from the Kodiak region due to either individual prey preferences or prey availability. Application of a Bayesian mixing model to stable isotope analysis improves description of regional diets and comparison of these diets to resource availability and quality.
Postrelease dive ability in rehabilitated harbor seals
Authors: Morrison Catriona , Sparling Carol , Sadler Laila , Charles Alison , Sharples Ruth , McConnell Bernie
Published: July 2011

Abstract

The efficacy of seal rehabilitation is examined in a postrelease study of dive ability in harbor seal pups (Phoca vitulina) in the Wash, United Kingdom. Six rehabilitated seals were fitted with Sea Mammal Research Unit (SMRU) Argos Satellite Relay Data Logger tags and their individual dive behavior was monitored for an average of 122 d. The upper 90 percentile edge of dive behavior (dive duration [DD90] and percentage of time at‐sea spent in a dive [PD90]), in 7 d bins, was used as a proxy for physiological dive ability. The results are compared with data from five wild adult harbor seals. There was no statistically significant difference between (1) the mean track duration of rehabilitated seals (126.20 ± 27.48 [SD] d) and adult seals (150.2 ± 24.62 d) (P= 0.108), indicating no evidence that short‐term survival was less in the rehabilitated group; (2) the mean mass‐scaled DD90 of rehabilitated seals (3.95 ± 0.37 min) and adult seals (4.09 ± 0.55 min) (P= 0.632); and (3) the mean PD90 of rehabilitated seals (81.62 ± 1.21%) and adult seals (81.48 ± 3.93%) (P= 0.943). These three results all suggest the success of the rehabilitation program in terms of short‐term survival and dive ability.
A quantitative real‐time polymerase chain reaction assay for the seagrass pathogen Labyrinthula zosterae
Authors: BERGMANN NINA , FRICKE BIRGIT , SCHMIDT MARTINA C. , TAMS VERENA , BEINING KATRIN , SCHWITTE HILDEGARD , BOETTCHER ANNE A. , MARTIN DANIEL L. , BOCKELMANN ANNA‐CHRISTINA , REUSCH THORSTEN BH , RAUCH GISEP
Published: July 2011

The protist Labyrinthula zosterae (Phylum Bigyra, sensu Tsui et al. 2009) has been identified as a causative agent of wasting disease in eelgrass (Zostera marina), of which the most intense outbreak led to the destruction of 90% of eelgrass beds in eastern North America and western Europe in the 1930s. Outbreaks still occur today, albeit at a smaller scale. Traditionally, L. zosterae has been quantified by measuring the necrotic area of Z. marina leaf tissue. This indirect method can however only lead to a very rough estimate of pathogen load. Here, we present a quantitative real‐time polymerase chain reaction (qPCR) approach to directly detect and quantify L. zosterae in eelgrass tissue. Based on the internal transcribed spacer (ITS) sequences of rRNA genes, species‐specific primers were designed. Using our qPCR, we were able to quantify accurately and specifically L. zosterae load both from culture and eelgrass leaves using material from Europe and North America. Our detection limit was less than one L. zosterae cell. Our results demonstrate the potential of this qPCR assay to provide rapid, accurate and sensitive molecular identification and quantification of L. zosterae. In view of declining seagrass populations worldwide, this method will provide a valuable tool for seagrass ecologists and conservation projects.
Identifying grasslands suitable for cellulosic feedstock crops in the Greater Platte River Basin: dynamic modeling of ecosystem performance with 250 m eMODIS
Authors: Gu Yingxin , Boyte Stephen P. , Wylie Bruce K. , Tieszen Larry L.
Published: July 2011

This study dynamically monitors ecosystem performance (EP) to identify grasslands potentially suitable for cellulosic feedstock crops (e.g., switchgrass) within the Greater Platte River Basin (GPRB). We computed grassland site potential and EP anomalies using 9‐year (2000–2008) time series of 250 m expedited moderate resolution imaging spectroradiometer Normalized Difference Vegetation Index data, geophysical and biophysical data, weather and climate data, and EP models. We hypothesize that areas with fairly consistent high grassland productivity (i.e., high grassland site potential) in fair to good range condition (i.e., persistent ecosystem overperformance or normal performance, indicating a lack of severe ecological disturbance) are potentially suitable for cellulosic feedstock crop development. Unproductive (i.e., low grassland site potential) or degraded grasslands (i.e., persistent ecosystem underperformance with poor range condition) are not appropriate for cellulosic feedstock development. Grassland pixels with high or moderate ecosystem site potential and with more than 7 years ecosystem normal performance or overperformance during 2000–2008 are identified as possible regions for future cellulosic feedstock crop development (ca. 68 000 km2 within the GPRB, mostly in the eastern areas). Long‐term climate conditions, elevation, soil organic carbon, and yearly seasonal precipitation and temperature are important performance variables to determine the suitable areas in this study. The final map delineating the suitable areas within the GPRB provides a new monitoring and modeling approach that can contribute to decision support tools to help land managers and decision makers make optimal land use decisions regarding cellulosic feedstock crop development and sustainability.
The Association between Severity of Atherosclerosis and Lower Urinary Tract Function in Male Patients with Lower Urinary Tract Symptoms
Authors: TAKAHASHI Norio , SHISHIDO Keiichi , SATO Yuichi , OGAWA Soichiro , OGURO Toshiki , KATAOKA Masao , SHIOMI Homare , UCHIDA Hisashi , HAGA Nobuhiro , HOSOI Takayuki , NOMIYA Masanori , AIKAWA Ken , MURAKAMI Husao , YAMAGUCHI Osamu
Published: July 2011

Objectives: The present study was undertaken to investigate the association between the severity of atherosclerosis and lower urinary tract function in male patients with lower urinary tract symptoms.

Methods: Male patients with lower urinary tract symptoms were examined with routine investigation. The severity of atherosclerosis was assessed by ultrasound examination of carotid artery. Patients were divided into two groups: control group and atherosclerosis group. The voiding function and storage function were compared between the two groups.

Results: A total of 50 men (69.9 ± 9.1 years [mean ± standard deviation]) entered the study. There was no significant difference in age distribution (control group: 68.7 ± 7.6 years; atherosclerosis group: 72.5 ± 9.7 years) and prostate volume (control group: 26.5 ± 17.3 mL; atherosclerosis group: 22.2 ± 11.0 mL) between the two groups. In the voiding parameters, maximum flow rate in the atherosclerosis group (13.4 ± 5.5 mL/s, P < 0.05) was significantly lower than that in the control group (16.7 ± 7.7 mL/s). Postvoid residual urine volume showed no significant difference between the two groups. In the storage parameters, voided volume was significantly reduced in the atherosclerosis group (161.8 ± 46 mL, P < 0.05), as compared to control group (201.1 ± 78 mL). Moreover, daytime frequency was 7.13 ± 3.02 times in the control group, and significantly higher in the atherosclerosis group (8.75 ± 2.50 times, P < 0.05).

Conclusion: Development of atherosclerosis impairs both voiding and storage function independently of age, suggesting atherosclerosis leads to lower urinary dysfunction.
Effect of supplementation of soft drinks with green tea extract on their erosive potential against dentine
Authors: Barbosa CS , Kato MT , Buzalaf MAR
Published: July 2011

Background:  Matrix metalloproteinase (MMP) inhibitors reduce dentine erosion. This in vitro study evaluated the effect of the supplementation of soft drinks with green tea extract, a natural inhibitor of MMPs, on their erosive potential against dentine.

Methods:  For each drink tested (Coca‐Cola™, Kuat™ guarana, Sprite™ and light Coca‐Cola™), 40 dentine specimens were divided into two subgroups differing with respect to supplementation with green tea extract at 1.2% (OM24®, 100%Camellia sinensis leaf extract, containing 30 ± 3% of catechin; Omnimedica, Switzerland) or not (control). Specimens were subjected to four pH cycles, alternating de‐ and remineralization in one day. For each cycle, samples were immersed in pure or supplemented drink (10 minutes, 30 mL per block) and in artificial saliva (60 minutes, 30 mL per block) at 37 °C, under agitation. Dentine alterations were determined by profilometry (μm). Data were analysed by two‐way ANOVA and Bonferroni’s test (p < 0.05).

Results:  A significant difference was observed among the drinks tested with Sprite™ leading to the highest surface loss and light Coca‐Cola™ to the lowest. Supplementation with green tea extract reduced the surface loss by 15% to 40% but the difference was significant for Coca‐Cola™ only.

Conclusions:  Supplementation of soft drinks with green tea extract might be a viable alternative to reduce their erosive potential against dentine.
Seroprevalence of Seven Zoonotic Infections in Nunavik, Quebec (Canada)
Authors: Messier V. , Lévesque B. , Proulx J.‐F. , Rochette L. , Serhir B. , Couillard M. , Ward B. J. , Libman M. D. , Dewailly É. , Déry S.
Published: July 2011

In Nunavik, common practices and food habits such as consumption of raw meat and untreated water place the Inuit at risk for contracting zoonotic diseases. The aim of this study was to determine the seroprevalence of seven zoonotic infections among the permanent residents of Nunavik. The study was conducted in the fall 2004 as part of the Nunavik Health Survey. Blood samples from adults aged 18–74 years (n = 917) were collected and analysed for the presence of antibodies against Trichinella spp., Toxocara canis, Echinococcus granulosus, Brucella spp., Coxiella burnetii, Leptospira spp. and Francisella tularensis. Information on sociodemographic characteristics, traditional activities, drinking water supply and nutrition was gathered using english/inuktitut bilingual questionnaires. The chi‐squared test was used to evaluate associations between seropositivity and other measured variables. Statistically significant variables were included in a multivariate logistic regression model to control for confounding factors. Estimated seroprevalences were 8.3% for E. granulosus, 3.9% for T. canis, 5.9% for Leptospira spp. and 18.9% for F. tularensis. Seroprevalence was ≤1% for Trichinella spiralis, Brucella spp. and C. burnetii. For most infections, seropositivity tended to increase with age. In multivariate analyses, seroprevalence was positively (i.e. directly) associated with age and residence in the Ungava coast area for F. tularensis; age and residence in the Hudson coast area for T. canis; female gender, lower level of schooling and frequent cleaning of water reservoirs for E. granulosus. No risk factor for Leptospira spp. infection was identified. No associations were detected with regards to food habits or environmental exposures. A small but significant portion of the Nunavik population has serologic evidence of exposure to at least one of the pathogenic microorganisms investigated. Further studies are needed to better understand the mechanisms for transmission of zoonotic infections and their potential reservoirs in Nunavik.
Psychometric properties and population‐based norms of the Life Orientation Test Revised (LOT‐R)
Authors: Glaesmer Heide , Rief Winfried , Martin Alexandra , Mewes Ricarda , Brähler Elmar , Zenger Markus , Hinz Andreas
Published: July 2011

Objectives. The relevance of the construct optimism in health psychology has been convincingly demonstrated in numerous studies. Population‐based studies about dispositional optimism and the psychometric properties of the Life Orientation Test LOT‐R as well as population‐based norms are lacking.

Design. A representative population survey in Germany was conducted to investigate psychometric properties of the LOT‐R and to deliver population‐based norms.

Methods. A representative sample of 2,372 adults aged 18–93 years were screened using self‐rating instruments.

Results. The confirmatory factor analysis (CFA) confirmed two factors. Optimism and pessimism are negatively correlated (r=−.20). Indications for convergent validity were demonstrated with depression, satisfaction with life, subjective state of health and health care utilization. Optimism is more strongly related to all indicators than pessimism. Since there are only marginal age and gender differences, norm data are given for the entire population.

Conclusions. Our study confirms the bi‐dimensionality of the LOT‐R and thus underpins that optimism and pessimism are two independent constructs rather than a single bipolar trait. Psychometric properties were found to be satisfactory. Together with the norm values reported in the paper, this instrument can, thus, be employed to measure dispositional optimism or pessimism in individual diagnostics as well as in epidemiological research.
Neural mechanisms of the automatic processing of emotional information from faces and voices
Authors: Straube Thomas , Mothes‐Lasch Martin , Miltner Wolfgang H. R.
Published: July 2011

Theoretical accounts suggest an increased and automatic neural processing of emotional, especially threat‐related, facial expressions and emotional prosody. In line with this assumption, several functional imaging studies showed activation to threat‐related faces and voices in subcortical and cortical brain areas during attentional distraction or unconscious stimulus processing. Furthermore, electrophysiological studies provided evidence for automatic early brain responses to emotional facial expressions and emotional prosody. However, there is increasing evidence that available cognitive resources modulate brain responses to emotional signals from faces and voices, even though conflicting findings may occur depending on contextual factors, specific emotions, sensory modality, and neuroscientific methods used. The current review summarizes these findings and suggests that further studies should combine information from different sensory modalities and neuroscientific methods such as functional neuroimaging and electrophysiology. Furthermore, it is concluded that the variable saliency and relevance of emotional social signals on the one hand and available cognitive resources on the other hand interact in a dynamic manner, making absolute boundaries of the automatic processing of emotional information from faces and voices unlikely.
On the Precision and Complexity of Numerical Contact Calculations
Authors: Lubrecht A. A.
Published: July 2011

The current paper analyses the complexity and precision of FEM calculations in 2 dimensional solid mechanics. The work shows that both grid refinement and domain enlargement are required to increase precision.
A 3D Compressible Flow Model for Weak Rotating Waves in Vaneless Diffusers—Part I: The Model and Mach Number Effects
Authors: Chen Hua , Shen Feng , Zhu Xiao-Cheng , Du Zhao-Hui
Published: July 2011

A three-dimensional compressible flow model is presented to study the occurrence of weak rotating waves in vaneless diffusers of centrifugal compressors. The diffuser considered has two parallel walls, and the undisturbed flow is assumed to be circumferentially uniform, isentropic, and to have no axial velocity. Linearized 3D compressible Euler equations were casted on a rotating coordinate system traveling at the same angular speed as the wave cells. A uniform static pressure at the outlet of the diffuser was imposed. Complex functions of the solutions to the equations were obtained by a second-order finite difference method and the singular value decomposition technique. The influences of the inlet Mach number of undisturbed flow, inlet spanwise distribution of undisturbed radial velocity, and diffuser radius ratio on the rotating waves were studied and results show that (1) the critical flow angle and rotating wave speed are both affected by the Mach number. However, the angle only increases slightly with the Mach number while the wave speed increases rapidly with the Mach number; (2) inlet distribution has minor influences on diffuser instability but the wave speed increases with the inlet distortion; (3) diffuser instability increases rapidly and the wave speed decreases quickly with the diffuser radius ratio; and (4) backward traveling rotating wave may occur if diffuser is sufficiently long and the inlet Mach number is sufficiently small.
Effect of Impeller Blade Loading on Compressor Stage Performance in a High Specific Speed Range
Authors: Shibata Takanori , Yagi Manabu , Nishida Hideo , Kobayashi Hiromi , Tanaka Masanori
Published: July 2011

The authors previously found that compressor stage efficiency in a high specific speed range was significantly improved by employing an increased relative velocity diffusion ratio coupled with a high backsweep angle (Shibata et al., “Performance Improvement of a Centrifugal Compressor Stage by Increasing Degree of Reaction Optimizing Blade Loading of a 3D-Impeller,” ASME Paper No. GT2009-59588). In spite of such a high relative velocity diffusion ratio, the same surge margin as with a conventional design was able to be achieved by using a special front loading distribution with a lightly loaded inducer. In the present study, the blade loading distribution was further optimized in order to achieve a larger surge margin than previously. Four types of fully shrouded impellers were designed, manufactured, and tested to evaluate the effects of blade loading, backsweep angle, and relative velocity diffusion ratio on compressor performance. The design suction flow coefficient was 0.125 and the machine Mach number was 0.87. Test results showed that the developed impeller achieved 3.8% higher stage efficiency and 11% larger surge margin than the conventional design without reducing the pressure coefficient and choke margin. It was concluded that aft loading coupled with a high degree of reaction was a very effective way to improve surge margin as well as stage efficiency. Stator matching was also investigated by changing the design incidence angle, which was shown to have a little influence on surge margin in the present test results.
Deposition Near Film Cooling Holes on a High Pressure Turbine Vane
Authors: Ai Weiguo , Murray Nathan , Fletcher Thomas H. , Harding Spencer , Lewis Scott , Bons Jeffrey P.
Published: July 2011

Deposition on film-cooled turbine components was studied in an accelerated test facility. The accelerated deposition facility seeds a natural-gas burning combustor with finely ground coal ash particulate at 1180°C and 180 m/s (M=0.25). Both cylindrical and shaped holes, with and without thermal barrier coating, were studied over a range of blowing ratios from 0.5 to 4.0. Coolant density ratios were maintained at values from 2.1 to 2.4. Deposition patterns generated with the cylindrical film cooling holes indicated regions of low deposition in the path of the coolant with heightened deposition between film holes. This distinctive pattern was more accentuated at higher blowing ratios. Optical temperature measurements of the turbine component surface during deposition showed elevated temperatures between coolant paths. This temperature nonuniformity became more accentuated as deposition increased, highlighting a mechanism for deposition growth that has been documented on in-service turbines as well. The shaped-hole components exhibited little or no deposition in the region just downstream of the holes due to the distributed coolant film. Close cylindrical hole spacing of 2.25d displayed similar behavior to the shaped-hole configuration.
Film Cooling Performance of Sharp Edged Diffuser Holes With Lateral Inclination
Authors: Heneka Christian , Schulz Achmed , Bauer Hans-Jörg , Heselhaus Andreas , Crawford Michael E.
Published: July 2011

An experimental study on film cooling performance of laterally inclined diffuser shaped cooling holes is presented. The measurements have been conducted on a flat plate with coolant ejected from a plenum. The film cooling effectiveness downstream of a row of four laidback fanshaped holes with sharp edged diffusers has been determined by means of infrared (IR) thermography. A variety of geometric parameters has been tested, including the inclination angle, the compound angle, the area ratio, and the pitch to diameter ratio. All tests have been performed over a wide range of engine typical blowing ratios (M=0.5–3.0). The hot gas Reynolds number and the coolant to hot gas density ratio have been kept constant close to engine realistic conditions. The results, presented in terms of contour plots of related adiabatic film cooling effectiveness as well as laterally averaged related values, clearly show the influences of the cooling hole geometry. Increasing the area ratio and the compound angle, in general, leads to higher values of the effectiveness, whereas steeper injection causes a reduction of the effectiveness.
Load Capacity and Durability of H-DLC Coated Hydrodynamic Thrust Bearings
Authors: Jahanmir Said , Hunsberger Andrew Z. , Heshmat Hooshang
Published: July 2011

Hydrogenated diamondlike carbon (H-DLC) coatings provide excellent wear resistance and low friction for bearing applications. However, the use of such coatings with aqueous lubricants could pose some difficulties due to the hydrophobic nature of the surface. A thrust bearing tribometer was used to compare performance of hydrophilic and hydrophobic surfaces in hydrodynamic lubrication with a mixture of water and glycerol as the lubricant. Hydrophobic surfaces on both runner and bearing were achieved with the deposition of H-DLC films on titanium alloy surfaces. Hydrophilic surfaces were created through modification of H-DLC surface with covalently bonded heparin. Several possible combinations of hydrophobic and hydrophilic surface conditions were used on the bearing and runner surfaces to provide full-wetting, partial-wetting, and half-wetting conditions. The experimental results confirmed that load support is still possible, when the bearing is half-wetted or partially wetted. However, the full-wetted bearing combination (i.e., Reynolds no-slip boundary condition) provided the highest load support. Introduction of slip at the surface resulted in a lower measured torque. Heparin treatment resulted in a lower than expected static friction and friction in full lubrication regime. The durability of coated surfaces was evaluated in a series of start–stop tests and in impact tests. The results confirmed that the coatings are stable and survive the test regiment that exceeded 50 test cycles; whereas the uncoated titanium alloy bearing surfaces were damaged after ten test cycles.
Impact Micro-Elastohydrodynamics in Point Contacts
Authors: Kaneta M. , Guo F. , Wang J.
Published: July 2011

The influences of a single bump (dent) or regularly arranged bumps (dents) on the film thickness in impact circular elasthydrodynamic lubrication (EHL) contacts lubricated with a Newtonian lubricant are investigated numerically. It has been found that the deformation of the bump or the dent at the contact center depends mainly on the macroscopic pressure distribution produced between the smooth surfaces by impact. The macroscopic pressure distribution is influenced by the initial impact gap, the loading speed, and the mass of the moving body. The central bump or dent hardly deforms when the initial impact gap or the base radius of the bump or dent is small. When the initial impact gap is large and the radius of the base of the central bump is not so small, the oil is entrapped in the bump, and micro-dimple is formed. The deformation of noncentral bumps or dents is mainly influenced by the film profile under conditions of smooth surfaces.
An empirical model of diagnostic x‐ray attenuation under narrow‐beam geometry
Authors: Mathieu Kelsey B. , Kappadath S. Cheenu , White R. Allen , Atkinson E. Neely , Cody Dianna D.
Published: July 2011

Purpose:

The purpose of this study was to develop and validate a mathematical model to describe narrow‐beam attenuation of kilovoltage x‐ray beams for the intended applications of half‐value layer (HVL) and quarter‐value layer (QVL) estimations, patient organ shielding, and computer modeling.

Methods:

An empirical model, which uses the Lambert W function and represents a generalized Lambert‐Beer law, was developed. To validate this model, transmission of diagnostic energy x‐ray beams was measured over a wide range of attenuator thicknesses [0.49–33.03 mm Al on a computed tomography (CT) scanner, 0.09–1.93 mm Al on two mammography systems, and 0.1–0.45 mm Cu and 0.49–14.87 mm Al using general radiography]. Exposure measurements were acquired under narrow‐beam geometry using standard methods, including the appropriate ionization chamber, for each radiographic system. Nonlinear regression was used to find the best‐fit curve of the proposed Lambert W model to each measured transmission versus attenuator thickness data set. In addition to validating the Lambert W model, we also assessed the performance of two‐point Lambert W interpolation compared to traditional methods for estimating the HVL and QVL [i.e., semilogarithmic (exponential) and linear interpolation].

Results:

The Lambert W model was validated for modeling attenuation versus attenuator thickness with respect to the data collected in this study (R2 > 0.99). Furthermore, Lambert W interpolation was more accurate and less sensitive to the choice of interpolation points used to estimate the HVL and/or QVL than the traditional methods of semilogarithmic and linear interpolation.

Conclusions:

The proposed Lambert W model accurately describes attenuation of both monoenergetic radiation and (kilovoltage) polyenergetic beams (under narrow‐beam geometry).
Impact of the calculation resolution of AAA for small fields and RapidArc treatment plans
Authors: Ong Chin Loon , Cuijpers Johan P. , Senan Suresh , Slotman Ben J. , Verbakel Wilko F. A. R.
Published: July 2011

Purpose:

To investigate the impact of the calculation resolution of the anisotropic analytical algorithms (AAA) for a variety of small fields in homogeneous and heterogeneous media and for RapidArc plans.

Methods:

Dose distributions calculated using AAA version 8.6.15 (AAA8) and 10.0.25 (AAA10) were compared to measurements performed with GafChromic EBT film, using phantoms made of polystyrene or a combination of polystyrene and cork. The accuracy of the algorithms calculated using grid resolutions of 2.5 and 1.0 mm was investigated for different field sizes, and for a limited selection of RapidArc plans (head and neck, small meningioma, and lung). Additional plans were optimized to create excessive multileaf collimator modulation and measured on a homogenous phantom. Gamma evaluation criterion of 3% dose difference and 2‐ or 1‐mm distance to agreement (DTA) were applied to evaluate the accuracy of the algorithms.

Results:

For fields ≤3 × 3 cm2, both versions of AAA predicted lower peak doses and broader penumbra widths than the measurements. However, AAA10 and a finer calculation grid improved the agreement. For RapidArc plans with many small multileaf collimator (MLC) segments and relatively high number of monitor units (MU), AAA8 failed to identify small dose peaks within the target. Both versions performed better in polystyrene than in cork. In homogeneous cork layers, AAA8 underestimated the average target dose for a clinical lung plan. This was improved with AAA10 calculated using a 1 mm grid.

Conclusions:

AAA10 improves the accuracy of dose calculations, and calculation grid of 1.0 mm is superior to using 2.5 mm, although calculation times increased by factor of 5. A suitable upper MU constraint should be assigned during optimization to avoid plans with high modulation. For plans with a relative high number of monitor units, calculations using 1 mm grid resolution are recommended. For planning target volume (PTV) which contains relatively large area of low density tissue, users should be aware of possible dose underestimation in the low density region and recalculation with AAA10 grid 1.0 mm is recommended.