bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality of life and treatment satisfaction in the context of diabetes self‐management education
Authors: Gurková Elena , Čáp Juraj , Žiaková Katarína
Published: March 2009

The aim of this study is to identify and compare factors affecting quality of life and treatment satisfaction in people attending the structured educational programme for patients with intensified insulin therapy. A sample of 104 patients was recruited from diabetes specialized centre between November 2006 and March 2007. For measure patient's quality of life, the Audit Diabetes Dependent Quality of Life questionnaire and for measure patient's satisfaction with their treatment regimen, the Diabetes Treatment Satisfaction Questionnaire status version was used. Treatment satisfaction has different variables or predictors from quality of life. Quality of life was affected by the number of reported diabetic late complications, type of insulin regimen, age and diabetes duration. Type of insulin regimen, the frequency of blood glucose self‐monitoring and perceived frequency of hyperglycaemia demonstrated the significant association with treatment satisfaction. Our findings might help health‐care professionals have a deeper understanding of the factors affecting quality of life and treatment satisfaction and thereby aid in the design of strategies to maintain or improve quality of life and treatment satisfaction.
Relationship between parental knowledge of fetal gender and newborns' birthweight among Jordanian families
Authors: Al‐Akour Nemeh
Published: March 2009

The purpose of this study was to examine the relationship between women knowing the fetal gender and their newborns' birthweight. Four‐hundred and eighty‐four post‐partum mothers before discharge from the maternity unit participated in this study. We collected our data from the women by using two sources: a demographic data questionnaire and reviews of hospital records. For this study, we considered normal birthweight as > 2500 and < 4000 g and low birthweight as < 2500 g. The findings of the study suggested that knowledge of fetal gender was significantly related to the mean birthweight of newborns. When the gender was known prenatally, the mean birthweight of male newborns was significantly higher than that of female newborns. Also knowledge of fetal gender was found to increase the probability of low birthweight among female newborns compared with male newborns. Identifying sociocultural factors that might be linked to the gender preference could improve mothers' and their newborns' well‐beings. Nurses have to be aware of the consequences of gender preference such as low birthweight.
A descriptive study of douching practices in Turkish women
Authors: Hacıalioğlu Nazlı , Nazik Evşen , Kılıç Meral
Published: March 2009

Vaginal douching is a common hygiene practice for many women all over the world. Little is known about the beliefs and attitudes that promote and maintain douching practices. Therefore, the aim of this study is to evaluate the status of vaginal douching practices of women in the Erzurum province of Turkey. The present study was a descriptive and cross‐sectional quality. All participants were 15–49 years of age and all were married. Data analysis included descriptive statistics and χ2 test. The present study revealed that the frequency of douching was 51.4% among women and that the most common reason for their habit was feminine hygiene and the most popular material used was water. A statistically significant relationship was found between the habit of doing the vaginal douching and the educational level, age of marriage, number of births, case of genital infections within the last year and presence of complaints indicating vaginal infections for the last month. This study provides preliminary information about women's douching practices and attitudes. It might also provide information to health‐care practitioners in their efforts to educate women on the adverse effects of vaginal douching.
The predictive role of C‐reactive protein in patients with hypertension and subclinical atherosclerosis
Authors: Rizzo M. , Corrado E. , Coppola G. , Muratori I. , Mezzani A. , Novo G. , Novo S.
Published: March 2009

Background: Recent guidelines published by the joint European Society of Hypertension/European Society of Cardiology have suggested the inclusion of C‐reactive protein (CRP) in the standard assessment of cardiovascular risk in hypertensive patients, but few data are available on the role of CRP in patients with carotid lesions.

Methods: We studied 472 patients, 236 with and 236 without hypertension, sex‐ and age‐matched, with and without early stages of atherosclerosis (e.g. those with an asymptomatic intima–media thickness of >0.9 mm), the influence of all the other traditional cardiovascular risk factors (e.g. older age, male sex, obesity, diabetes, smoking habit, family history of coronary artery disease, dyslipidaemia) and of high‐sensitivity CRP levels on cerebrovascular and cardiovascular events in a 5‐year follow up.

Results: At the end of follow up, patients with hypertension had more events than those without (25% vs 17%, P < 0.05). Proportional hazard analysis revealed in the group of patients without hypertension the presence of baseline carotid lesions (P= 0.02) as predictor of events. In patients with hypertension, the presence of baseline carotid lesions (P= 0.04) and elevated CRP levels (P= 0.02) predicted clinical events. Patients with hypertension also showed a significant relationship between clinical events and quintiles of CRP levels (P < 0.01).

Conclusion: Beyond the utility of high‐sensitivity CRP levels in the prediction of early and late stages of atherosclerosis and subsequently on its association with clinical events, the therapeutic implications of these results remain to be evaluated by further studies.
End‐of‐life decision‐making in individuals with Locked‐in syndrome in the acute period after brainstem stroke
Authors: Anderson J. F. I. , Augoustakis L. V. , Holmes R. J. , Chambers B. R.
Published: March 2009

Locked‐in syndrome (LIS) is commonly associated with a poor prognosis, particularly if the aetiology is stroke. Dealing with individuals with LIS and a poor prognosis raises the issue of introducing end‐of‐life discussions with the patient and/or family in the acute period of the illness. Existing literature regarding LIS provides little guidance about end‐of‐life decision‐making in the acute management phase. We aim to provide some guidance for clinicians holding end‐of‐life discussions in the acute management period. We report two cases of relatively young individuals with LIS secondary to brainstem stroke. Both cases had a very poor prognosis and end‐of‐life discussions were commenced by the treating team in the acute phase. Despite the severity of their conditions, in neither case were end‐of‐life discussions well tolerated by the family in the weeks following admission. We suggest that LIS patients and their families, who have chosen to persist with full medical management after diagnosis of LIS, should be provided with sufficient time to adjust to the catastrophic changes that have occurred before further end‐of‐life discussions are pursued. Education and support are likely to be highly beneficial in the acute period post stroke as they allow the patient and family to develop a realistic understanding of the likely outcomes of their decisions.
An Australian cardiovascular risk equation for type 2 diabetes: the Fremantle Diabetes Study
Authors: Davis W. A. , Knuiman M. W. , Davis T. M. E.
Published: March 2009

Background: There is no valid cardiovascular disease (CVD) risk prediction equation for Australians with diabetes. The aim of this study is to develop and validate a multivariate risk function for 5‐year cardiovascular risk prediction in Australian type 2 diabetes patients.

Methods: The Fremantle Diabetes Study is a community‐based longitudinal observational study. A total of 1240 type 2 diabetic patients (95.8% of the baseline cohort) with all required risk factor data were followed from baseline (1993–1996) for 5 years or until they experienced a cardiovascular event or died, whichever came first. CVD during follow up was defined as hospitalization for/with myocardial infarction or stroke, and death from cardiac or cerebrovascular causes or sudden death. Validation of the algorithm was performed on an independent diabetic cohort from the Busselton Health Study.

Results: During 5570 patient‐years of follow up, 185 (14.9%) had at least one CVD event and 175 (14.1%) died (57.7% from CVD). Variables in the final model comprised age, sex, prior CVD, ln(urinary albumin : creatinine ratio), lnHbA1c, ln(high density lipoprotein‐cholesterol), Southern European ethnic background and Aboriginality. The mean 5‐year predicted risk of a CVD event was 15.5%. Applied to the Busselton cohort, discrimination of the model was good (AUC = 0.84, P < 0.001) as was the goodness‐of‐fit (Hosmer–Lemeshow Ĉ‐test, P= 0.85) and accuracy (mean squared error (95% confidence interval) = 0.09 (0–0.76)). The positive and negative predictive values for a 10% 5‐year CVD risk cut‐off were 23.4% and 97.7% respectively.

Conclusion: This simple diabetes‐specific 5‐year CVD risk equation is the first validated, population‐based Australian model. It should have a role in diabetes management in primary and specialist care.
Acidosis in the hospital setting: is metformin a common precipitant?
Authors: Scott K. A. , Martin J. H. , Inder W. J.
Published: March 2009

Background: Acidosis is commonly seen in the acute hospital setting, and carries a high mortality. Metformin has been associated with lactic acidosis, but it is unclear how frequently this is a cause of acidosis in hospitalized inpatients. The aim of this study is to explore the underlying comorbidities and acute precipitants of acidosis in the hospital setting, including the relationship between type 2 diabetes (T2DM) and metformin use.

Methods: Retrospective review. Cases of acidosis were identified using the hospital discharge code for acidosis for a 3‐month period: October–December 2005.

Results: A total of 101 episodes of acidosis were identified: 29% had isolated respiratory acidosis, 31% had metabolic acidosis and 40% had a mixed respiratory and metabolic acidosis. There were 28 cases of confirmed lactic acidosis. Twenty‐nine patients had T2DM, but only five of the subjects with T2DM had lactic acidosis; two were on metformin. The major risk factors for development of lactic acidosis were hepatic impairment (OR 33.8, P = 0.01), severe left ventricular dysfunction (OR 25.3, P = 0.074) and impaired renal function (OR 9.7, P = 0.09), but not metformin use.

Conclusion: Most cases of metabolic and lactic acidosis in the hospital setting occur in patients not taking metformin. Hepatic, renal and cardiac dysfunction are more important predictors for the development of acidosis.
Measuring the quality of hospital care: an inventory of indicators
Authors: Copnell B. , Hagger V. , Wilson S. G. , Evans S. M. , Sprivulis P. C. , Cameron P. A.
Published: March 2009

Background: Development of indicators to measure health‐care quality has progressed rapidly. This development has, however, rarely occurred in a systematic fashion, and some aspects of care have received more attention than others. The aim of this study is to identify and classify indicators currently in use to measure the quality of care provided by hospitals, and to identify gaps in current measurement.

Methods: A literature search was undertaken to identify indicator sets. Indicators were included if they related to hospital care and were clearly being collected and reported to an external body. A two‐person independent review was undertaken to classify indicators according to aspects of care provision (structure, process or outcome), dimensions of quality (safety, effectiveness, efficiency, timeliness, patient‐centredness and equity), and domain of application (hospital‐wide, surgical and non‐surgical clinical specialities).

Results: 383 discrete indicators were identified from 22 source organizations or projects. Of these, 27.2% were relevant hospital‐wide, 26.1% to surgical patients and 46.7% to non‐surgical specialities, departments or diseases. Cardiothoracic surgery, cardiology and mental health were the specialities with greatest coverage, while nine clinical specialities had fewer than three specific indicators. Processes of care were measured by 54.0% of indicators and outcomes by 38.9%. Safety and effectiveness were the domains most frequently represented, with relatively few indicators measuring the other dimensions.

Conclusion: Despite the large number of available indicators, significant gaps in measurement still exist. Development of indicators to address these gaps should be a priority. Work is also required to evaluate whether existing indicators measure what they purport to measure.
Probabilistic high cycle fatigue behaviour of nodular cast iron containing casting defects
Authors: NASR A. , BOURAOUI CH. , FATHALLAH R. , NADOT Y.
Published: March 2009

Theoretical and experimental investigations were combined to characterize the influence of surface casting defects (shrinkages) on the high cycle fatigue (HCF) reliability. On fracture surfaces of fatigue samples, the defect is located at the surface. The shape used for the calculation is a spherical void with variable radius. Finite‐element simulations were then performed to determine stress distribution around defects for different sizes and different loadings. Correlated expressions of the maximum hydrostatic stress and the amplitude of the shear stress were obtained by using the response surface technique. The loading representative point in the HCF criterion was then transformed into a scattering surface, which has been obtained by a random sampling of the defect sizes. The HCF reliability has been computed by using the Monte Carlo simulation method. Tension and torsion fatigue tests were conducted on nodular cast iron with quantification of defect size on the fracture surface. The S–N curves show a large fatigue life scattering; shrinkages are at the origin of the fatal crack leading to the final failure. The comparison of the computed HCF reliability to the experimental results shows a good agreement. The capability of the proposed model to take into account the influence of the range of the defect sizes and the type of its statistical distribution has been demonstrated. It is shown that the stress distribution at the fatigue limit is log‐normal, which can be explained by the log‐normal defect distribution in the nodular cast iron tested.
An invariant‐based approach for high‐cycle fatigue calculation
Authors: CRISTOFORI A. , TOVO R.
Published: March 2009

Fatigue failures of in‐service components are frequently due to multiaxial loadings; therefore, damage quantification in such conditions is important to many industrial applications. In this work a multiaxial criterion suitable for high‐cycle fatigue assessment is formalized. It makes use of hydrostatic stress component and deviatoric stress component to estimate fatigue damage. A new formulation for the equivalent amplitude of the deviatoric component is formalized and compared with definitions proposed by Deperrois and Li and De Freitas. Damage evaluation procedure is discussed for deterministic loads and explicit analytical formulation is presented for sinusoidal loadings. Fatigue criterion is applied to experimental data taken from literature, related to several materials subjected to either in‐phase or out‐of‐phase loads. It is shown that the new approach gives good predictions for both smooth and notched specimens. A similar comparison between experimental and theoretical results is also presented for other common criteria. It appears that the quality of the fatigue assessments obtained with the present criterion is better or, at most, similar to that of the other criteria analysed.
A multiaxial fretting fatigue test for spline coupling contact
Authors: WAVISH P. M. , HOUGHTON D. , DING J. , LEEN S. B. , WILLIAMS E. J. , McCOLL I. R.
Published: March 2009

A novel fretting fatigue experimental methodology is presented for mimicking the salient fretting variables for arbitrary axial locations within a complex spline coupling geometry, under combined torque, axial loading and rotating bending moment. The approach permits the simulation, in a simplified test arrangement, of the superimposed multiaxial fretting conditions between the spline teeth. This is achieved via the combination of a low frequency in‐plane cyclic normal clamping load and a higher frequency out‐of‐plane cyclic fatigue stress. The latter is known from spline fatigue tests to play a critical role, along with torque and axial loads, in fretting fatigue cracking of splines.
Fatigue fracture toughness of metals
Authors: TROSHCHENKO V. T.
Published: March 2009

The paper considers the peculiarities of fatigue crack propagation and final fracture of metals under cyclic loading. It is shown that the value of the fatigue fracture toughness of steels in an embrittled state is appreciably lower than that of the fracture toughness under static loading. A model of the transition from stable to unstable fatigue crack propagation is justified.
Corticomotor excitability of back muscles is affected by intervertebral disc lesion in pigs
Authors: Hodges Paul W. , Galea Mary P. , Holm Sten , Holm Allison Kaigle
Published: March 2009

Morphological and behavioural changes in back muscles are common in back pain and injury. Recent data indicate a rapid reduction in the size of the multifidus, a deep back muscle, within 3 days of experimental intervertebral disc (IVD) injury in pigs. A reduced neural drive may contribute to this. We investigated changes in corticomotor excitability following IVD lesion by evaluation of the response of back muscles to electrical stimulation of the motor cortex. Motor evoked potentials (MEPs) were studied in 12 Swedish landrace pigs before injury, immediately after abdominal incision, immediately after L3‐4 IVD lesion with a scalpel, and 15 min later. In two animals, responses were also evoked by descending volleys excited at the level of the mastoid processes (cervicomedullary evoked potentials) without motor cortex activation. In five animals, a sham procedure was followed without IVD lesion. MEPs were recorded in short (deep) and long (superficial) fibres of the multifidus at L3‐5 on the lesioned side and at L4 contralaterally with intramuscular wire electrodes. Although the MEP amplitude increased in several muscles after incision, at 15 min after IVD lesion only the MEP amplitude of the deep L4 multifidus on the lesioned side was increased [36% (SD 15%), P < 0.05]. There were no changes in MEP amplitude after 15 min at adjacent or contralateral levels. The response to cervicomedullary stimulation reduced slightly. This suggests that the increased MEP amplitude was due to changes in cortical excitability. These data indicate that IVD lesion induces localized increases, and not decreases, in the excitability of cortical inputs to the deep paraspinal muscles that cross a lesioned disc.
Attenuated human auditory middle latency response and evoked 40‐Hz response to self‐initiated sounds
Authors: Baess Pamela , Widmann Andreas , Roye Anja , Schröger Erich , Jacobsen Thomas
Published: March 2009

For several modalities, it has been shown that the processing of sensory information generated by our own actions is attenuated relative to the processing of sensory information of externally generated stimuli. It has been proposed that the underlying mechanism builds predictions about the forthcoming sensory input and forwards them to the respective sensory processing levels. The present study investigated whether early auditory processing is suppressed by the top‐down influences of such an internal forward model mechanism. To this end, we compared auditory middle latency responses (MLRs) and evoked 40‐Hz responses elicited by self‐initiated sounds with those elicited by externally initiated but otherwise identical sounds. In the self‐initiated condition, the amplitudes of the Pa (27–33 ms relative to sound onset) and Nb (40–46 ms) components of the MLRs were significantly attenuated when compared to the responses elicited by click sounds presented in the externally initiated condition. Similarly, the evoked activity in the 40‐Hz and adjacent frequency bands was attenuated. Considering that previous research revealed subcortical and auditory cortex contributions to MLRs and 40‐Hz responses, our results support the existence of auditory suppression effects with self‐initiated sounds on temporally and structurally early auditory processing levels. This attenuation in the processing of self‐initiated sounds most probably contributes to the optimal processing of concurrent external acoustic events.
Expression of Zif268 in the granule cell layer of the adult mouse olfactory bulb is modulated by experience
Authors: Busto Germain U. , Elie Julie E. , Kermen Florence , Garcia Samuel , Sacquet Joëlle , Jourdan François , Marcel Dominique , Mandairon Nathalie , Didier Anne
Published: March 2009

Behavioral and physiological evidence indicates that odor processing in the main olfactory bulb is influenced by olfactory experience. At the cellular level, changes in inhibitory influence exerted by granular interneurons may contribute to restructuring odor representations. To assess experience‐dependent modulation in the responsiveness of granule cells, we measured the level and spatial distribution of odor‐induced expression of the immediate–early gene Zif268 in the granule cell layer of adult mice submitted or not to olfactory discrimination conditioning. We first show that stimulation by the reinforced odorant in conditioned animals did not induce any increase in Zif268 expression in contrast to stimulation with an unfamiliar odorant which induced an odor‐specific three‐fold increase in Zif268 expression. The same lack of Zif268 induction was observed in animals exposed to odorants without learning, indicating that familiarity to the odorant with or without conditioning similarly reduced responsiveness of granule cells to odorant stimulation. Second, conditioning induced a spatial reorganization of Zif268‐positive cells leading to higher contrast and significant enlargement of their distribution pattern. The latter effect was also present in animals exposed to the odorants without conditioning but was significantly weaker. Taken together, these data indicate that distinct populations of granule cells are solicited by odorant processing, depending on its familiarity or behavioral significance. Finally, we report that the expression pattern of Zif268 in the granule cell layer is constrained by anteroposterior and dorsolateral gradients in cell density, pointing to anatomical and possibly functional disparity within the layer.
On the positive side of error processing: error‐awareness positivity revisited
Authors: Shalgi Shani , Barkan Ido , Deouell Leon Y.
Published: March 2009

Performance errors are indexed in the brain even if they are not consciously registered, as demonstrated by the error‐related negativity (ERN or Ne) event‐related potential. It has recently been shown that another response‐locked potential, the error positivity (Pe), follows the Ne, but only in those trials in which the participants consciously detect making the error (‘Aware Errors’). In the present study we generalize these findings to an auditory task and investigate possible caveats in the interpretation of the Pe as an index of error awareness. In an auditory Go/No‐Go error‐awareness task (auditory EAT) participants pressed an additional ‘fix error’ button after noticing that they had made an error. As in visual tasks, the Ne was similar for aware (‘fixed’) and unaware (‘unfixed’) errors, while the Pe was enhanced only for Aware Errors. Within subjects, the Ne and Pe behaved in similar fashions for auditory and visual errors. A control condition confirmed that the awareness effect was not due to the requirement to report error awareness. These results reinforce the evidence in favor of the Pe as a correlate of conscious error processing, and imply that this process is not modality‐specific. Nevertheless, single‐trial analysis suggested that the Pe may be a delayed P3b related to stimulus processing rather than to response monitoring.
The maintenance of specific aspects of neuronal function and behavior is dependent on programmed cell death of adult‐generated neurons in the dentate gyrus
Authors: Kim Woon Ryoung , Park Ok‐hee , Choi Sukwoo , Choi Se‐Young , Park Soon Kwon , Lee Kea Joo , Rhyu Im Joo , Kim Hyun , Lee Yeon Kyung , Kim Hyun Taek , Oppenheim Ronald W. , Sun Woong
Published: March 2009

A considerable number of new neurons are generated daily in the dentate gyrus (DG) of the adult hippocampus, but only a subset of these survive, as many adult‐generated neurons undergo programmed cell death (PCD). However, the significance of PCD in the adult brain for the functionality of DG circuits is not known. Here, we examined the electrophysiological and behavioral characteristics of Bax‐knockout (Bax‐KO) mice in which PCD of post‐mitotic neurons is prevented. The continuous increase in DG cell numbers in Bax‐KO mice resulted in the readjustment of afferent and efferent synaptic connections, represented by age‐dependent reductions in the dendritic arborization of DG neurons and in the synaptic contact ratio of mossy fibers with CA3 dendritic spines. These neuroanatomical changes were associated with reductions in synaptic transmission and reduced performance in a contextual fear memory task in 6‐month‐old Bax‐KO mice. These results suggest that the elimination of excess DG neurons via Bax‐dependent PCD in the adult brain is required for the normal organization and function of the hippocampus.
Depth‐dependent detection of microampere currents delivered to monkey V1
Authors: Tehovnik Edward J. , Slocum Warren M.
Published: March 2009

Monkeys can detect electrical stimulation delivered to the striate cortex (area V1). We examined whether such stimulation is layer dependent. While remaining fixated on a spot of light, a rhesus monkey was required to detect a 100‐ms train of electrical stimulation delivered to a site within area V1. A monkey signaled the delivery of stimulation by depressing a lever after which he was rewarded with a drop of apple juice. Control trials were interleaved during which time no stimulation was delivered and the monkey was rewarded for not depressing the lever. Biphasic pulses were delivered at 200 Hz, and the current was typically at or < 30 μA using 0.2‐ms cathode‐first biphasic pulses. For some experiments, the pulse duration was varied from 0.05 to 0.7 ms and anode‐first pulses were used. The current threshold for detecting cathode‐first pulses 50% of the time was the lowest (< 10 μA) when stimulation was delivered to the deepest layers of V1 (between 1.0 and 2.5 mm below the cortical surface). Also, the shortest chronaxies (< 0.2 ms) and the shortest latencies (< 200 ms) for detecting the stimulation were observed at these depths. Finally, anode‐first pulses were most effective at evoking a detection response in superficial V1 and cathode‐first pulses were most effective at evoking a detection response in deep V1 (> 1.75 mm below the cortical surface). Accordingly, the deepest layers of V1 are the most sensitive for the induction of a detection response to electrical stimulation in monkeys.
The dorsomedial hypothalamic nucleus is not necessary for food‐anticipatory circadian rhythms of behavior, temperature or clock gene expression in mice
Authors: Moriya Takahiro , Aida Reiko , Kudo Takashi , Akiyama Masashi , Doi Masao , Hayasaka Naomi , Nakahata Norimichi , Mistlberger Ralph , Okamura Hitoshi , Shibata Shigenobu
Published: March 2009

Circadian rhythms in mammals are regulated by a light‐entrainable circadian pacemaker in the hypothalamic suprachiasmatic nucleus and food‐entrainable oscillators located elsewhere in the brain and body. The dorsomedial hypothalamic nucleus (DMH) has been proposed to be the site of oscillators driving food‐anticipatory circadian rhythms, but this is controversial. To further evaluate this hypothesis, we measured clock gene, temperature and activity rhythms in intact and DMH‐ablated mice. A single 4‐h midday feeding after an overnight fast inducedmPer1andmPer2mRNA expression in the DMH, arcuate nucleus, nucleus of the solitary tract and area postrema, and reset daily rhythms ofmPer1,mPer2andmBMAL1in the DMH, arcuate and neocortex. These rhythms persisted during 2 days of food deprivation after 12 days of scheduled daytime feeding. Acute induction of DMHmPer1andmPer2wasN‐methyl‐d‐aspartate (NMDA) receptor‐dependent, whereas rhythmic expression after 6 days of restricted feeding was not. Thermal DMH lesions did not affect acute induction or rhythmic expression of clock genes in other brain regions in response to scheduled daytime feeding. DMH lesions attenuated mean daily activity levels and nocturnality but did not affect food‐anticipatory rhythms of activity and body temperature in either light–dark or constant darkness. These results confirm that the DMH and other brain regions express circadian clock gene rhythms sensitive to daytime feeding schedules, but do not support the hypothesis that DMH oscillations drive food‐anticipatory behavioral or temperature rhythms.
Soil aggregation and carbon sequestration are tightly correlated with the abundance of arbuscular mycorrhizal fungi: results from long‐term field experiments
Authors: Wilson Gail W. T. , Rice Charles W. , Rillig Matthias C. , Springer Adam , Hartnett David C.
Published: March 2009

We examined the role of arbuscular mycorrhizal fungi (AMF) in ecosystems using soil aggregate stability and C and N storage as representative ecosystem processes. We utilized a wide gradient in AMF abundance, obtained through long‐term (17 and 6 years) large‐scale field manipulations. Burning and N‐fertilization increased soil AMF hyphae, glomalin‐related soil protein (GRSP) pools and water‐stable macroaggregates while fungicide applications reduced AMF hyphae, GRSP and water‐stable macroaggregates. We found that AMF abundance was a surprisingly dominant factor explaining the vast majority of variability in soil aggregation. This experimental field study, involving long‐term diverse management practices of native multispecies prairie communities, invariably showed a close positive correlation between AMF hyphal abundance and soil aggregation, and C and N sequestration. This highly significant linear correlation suggests there are serious consequences to the loss of AMF from ecosystems.
Categorical speech perception deficits distinguish language and reading impairments in children
Authors: Robertson Erin K. , Joanisse Marc F. , Desroches Amy S. , Ng Stella
Published: March 2009

We examined categorical speech perception in school‐age children with developmental dyslexia or Specific Language Impairment (SLI), compared to age‐matched and younger controls. Stimuli consisted of synthetic speech tokens in which place of articulation varied from ‘b’ to ‘d’. Children were tested on categorization, categorization in noise, and discrimination. Phonological awareness skills were also assessed to examine whether these correlated with speech perception measures. We observed similarly good baseline categorization rates across all groups; however, when noise was added, the SLI group showed impaired categorization relative to controls, whereas dyslexic children showed an intact profile. The SLI group showed poorer than expected between‐category discrimination rates, whereas this pattern was only marginal in the dyslexic group. Impaired phonological awareness profiles were observed in both the SLI and dyslexic groups; however, correlations between phonological awareness and speech perception scores were not significant. The results of the study suggest that in children with language and reading impairments, there is a significant relationship between receptive language and speech perception, there is at best a weak relationship between reading and speech perception, and indeed the relationship between phonological and speech perception deficits is highly complex.
Color correction for tone mapping
Authors: Mantiuk R. , Mantiuk R. , Tomaszewska A. , Heidrich W.
Published: March 2009

Tone mapping algorithms offer sophisticated methods for mapping a real‐world luminance range to the luminance range of the output medium but they often cause changes in color appearance. In this work we conduct a series of subjective appearance matching experiments to measure the change in image colorfulness after contrast compression and enhancement. The results indicate that the relation between contrast compression and the color saturation correction that matches color appearance is non‐linear and smaller color correction is required for small change of contrast. We demonstrate that the relation cannot be fully explained by color appearance models. We propose color correction formulas that can be used with existing tone mapping algorithms. We extend existing global and local tone mapping operators and show that the proposed color correction formulas can preserve original image colors after tone scale manipulation.
Mixing Fluids and Granular Materials
Authors: Lenaerts Toon , Dutré Philip
Published: March 2009

Fluid animations in computer graphics show interactions with various kinds of objects. However, fluid flowing through a granular material such as sand is still not possible within current frameworks. In this paper, we present the simulation of fine granular materials interacting with fluids. We propose a unified Smoothed Particle Hydrodynamics framework for the simulation of both fluid and granular material. The granular volume is simulated as a continuous material sampled by particles. By incorporating previous work on porous flow in this simulation framework we are able to fully couple fluid and sand. Fluid can now percolate between sand grains and influence the physical properties of the sand volume. Our method demonstrates various new effects such as dry soil transforming into mud pools by rain or rigid sand structures being eroded by waves.
Simulation of two‐phase flow with sub‐scale droplet and bubble effects
Authors: Mihalef Viorel , Metaxas Dimitris , Sussman Mark
Published: March 2009

We present a new Eulerian‐Lagrangian method for physics‐based simulation of fluid flow, which includes automatic generation of sub‐scale spray and bubbles. The Marker Level Set method is used to provide a simple geometric criterion for free marker generation. A filtering method, inspired from Weber number thresholding, further controls the free marker generation (in a physics‐based manner). Two separate models are used, one for sub‐scale droplets, the other for sub‐scale bubbles. Droplets are evolved in a Newtonian manner, using a density‐extension drag force field, while bubbles are evolved using a model based on Stokes' Law. We show that our model for sub‐scale droplet and bubble dynamics is simple to couple with a full (macro‐scale) Navier‐Stokes two‐phase flow model and is quite powerful in its applications. Our animations include coarse grained multiphase features interacting with fine scale multiphase features.
Scalable real‐time animation of rivers
Authors: Yu Qizhi , Neyret Fabrice , Bruneton Eric , Holzschuch Nicolas
Published: March 2009

Many recent games and applications target the interactive exploration of realistic large scale worlds. These worlds consist mostly of static terrain models, as the simulation of animated fluids in these virtual worlds is computationally expensive. Adding flowing fluids, such as rivers, to these virtual worlds would greatly enhance their realism, but causes specific issues: as the user is usually observing the world at close range, small scale details such as waves and ripples are important. However, the large scale of the world makes classical methods impractical for simulating these effects. In this paper, we present an algorithm for the interactive simulation of realistic flowing fluids in large virtual worlds. Our method relies on two key contributions: the local computation of the velocity field of a steady flow given boundary conditions, and the advection of small scale details on a fluid, following the velocity field, and uniformly sampled in screen space.
Shadowing Dynamic Scenes with Arbitrary BRDFs
Authors: Nowrouzezahrai Derek , Kalogerakis Evangelos , Fiume Eugene
Published: March 2009

We present a real‐time relighting and shadowing method for dynamic scenes with varying lighting, view and BRDFs. Our approach is based on a compact representation of reflectance data that allows for changing the BRDF at run‐time and a data‐driven method for accurately synthesizing self‐shadows on articulated and deformable geometries. Unlike previous self‐shadowing approaches, we do not rely on local blocking heuristics. We do not fit a model to the BRDF‐weighted visibility, but rather only to the visibility that changes during animation. In this manner, our model is more compact than previous techniques and requires less computation both during fitting and at run‐time. Our reflectance product operators can re‐integrate arbitrary low‐frequency view‐dependent BRDF effects on‐the‐fly and are compatible with all previous dynamic visibility generation techniques as well as our own data‐driven visibility model. We apply our reflectance product operators to three different visibility generation models, and our data‐driven model can achieve framerates well over 300Hz.
Anisotropic Radiance‐Cache Splatting for Efficiently Computing High‐Quality Global Illumination with Lightcuts
Authors: Herzog Robert , Myszkowski Karol , Seidel Hans‐Peter
Published: March 2009

Computing global illumination in complex scenes is even with todays computational power a demanding task. In this work we propose a novel irradiance caching scheme that combines the advantages of two state‐of‐the‐art algorithms for high‐quality global illumination rendering:lightcuts, an adaptive and hierarchical instant‐radiosity based algorithm and the widely used (ir)radiance caching algorithm for sparse sampling and interpolation of (ir)radiance in object space. Our adaptive radiance caching algorithm is based on anisotropic cache splatting, which adapts the cache footprints not only to the magnitude of the illumination gradient computed with light‐cuts but also to its orientation allowing larger interpolation errors along the direction of coherent illumination while reducing the error along the illumination gradient. Since lightcuts computes the direct and indirect lighting seamlessly, we use a two‐layer radiance cache, to store and control the interpolation of direct and indirect lighting individually with different error criteria. In multiple iterations our method detects cache interpolation errors above the visibility threshold of a pixel and reduces the anisotropic cache footprints accordingly. We achieve significantly better image quality while also speeding up the computation costs by one to two orders of magnitude with respect to the well‐known photon mapping with (ir)radiance caching procedure.
Physics‐driven Multi Dimensional Keyframe Animation for Artist‐directable Interactive Character
Authors: Mitake Hironori , Asano Kazuyuki , Aoki Takafumi , Marc Salvati , Sato Makoto , Hasegawa Shoichi
Published: March 2009

Various forms of art and entertainment involve many different characters, and advances in human interfaces have necessitated physical interactions in order to develop an improved sense of reality. In this paper we propose a method for generating the motions of characters using multidimensional keyframe animation in parallel with real‐time physical simulation. The method generates characters capable of physical interaction, and also allows animators to use traditional methods for designing character motion. We have implemented the system and confirmed its effectiveness experimentally.
Adaptive Caustic Maps Using Deferred Shading
Authors: Wyman Chris , Nichols Greg
Published: March 2009

Caustic maps provide an interactive image‐space method to render caustics, the focusing of light via reflection and refraction. Unfortunately, caustic mapping suffers problems similar to shadow mapping: aliasing from poor sampling and map projection as well as temporal incoherency from frame‐to‐frame sampling variations. To reduce these problems, researchers have suggested methods ranging from caustic blurring to building a multiresolution caustic map. Yet these all require a fixed photon sampling, precluding the use of importance‐based photon densities. This paper introduces adaptive caustic maps. Instead of densely sampling photons via a rasterization pass, we adaptively emit photons using a deferred shading pass. We describe deferred rendering for refractive surfaces, which speeds rendering of refractive geometry up to 25% and with adaptive sampling speeds caustic rendering up to 200%. These benefits are particularly noticable for complex geometry or using millions of photons. While developed for a GPU rasterizer, adaptive caustic map creation can be performed by any renderer that individually traces photons, e.g., a GPU ray tracer.
Into the Blue: Better Caustics through Photon Relaxation
Authors: Spencer B. , Jones M.W.
Published: March 2009

The photon mapping method is one of the most popular algorithms employed in computer graphics today. However, obtaining good results is dependent on several variables including kernel shape and bandwidth, as well as the properties of the initial photon distribution. While the photon density estimation problem has been the target of extensive research, most algorithms focus on new methods of optimising the kernel to minimise noise and bias. In this paper we break from convention and propose a new approach that directly redistributes the underlying photons. We show that by relaxing the initial distribution into one with a blue noise spectral signature we can dramatically reduce background noise, particularly in areas of uniform illumination. In addition, we propose an efficient heuristic to detect and preserve features and discontinuities. We then go on to demonstrate how reconfiguration also permits the use of very low bandwidth kernels, greatly improving render times whilst reducing bias.
Simplification of Articulated Meshes
Authors: Landreneau Eric , Schaefer Scott
Published: March 2009

We present a method for simplifying a polygonal character with an associated skeletal deformation such that the simplified character approximates the original shape well when deformed. As input, we require a set of example poses that are representative of the types of deformations the character undergoes and we produce a multi‐resolution hierarchy for the simplified character where all simplified vertices also have associated skin weights. We create this hierarchy by minimizing an error metric for a simplified set of vertices and their skin weights, and we show that this quartic error metric can be effectively minimized using alternating quadratic minimization for the vertices and weights separately. To enable efficient GPU accelerated deformations of the simplified character, we also provide a method that guarantees the maximum number of bone weights per simplified vertex is less than a user specified threshold at all levels of the hierarchy.
Fast BVH Construction on GPUs
Authors: Lauterbach C. , Garland M. , Sengupta S. , Luebke D. , Manocha D.
Published: March 2009

We present two novel parallel algorithms for rapidly constructing bounding volume hierarchies on manycore GPUs. The first uses a linear ordering derived from spatial Morton codes to build hierarchies extremely quickly and with high parallel scalability. The second is a top‐down approach that uses the surface area heuristic (SAH) to build hierarchies optimized for fast ray tracing. Both algorithms are combined into a hybrid algorithm that removes existing bottlenecks in the algorithm for GPU construction performance and scalability leading to significantly decreased build time. The resulting hierarchies are close in to optimized SAH hierarchies, but the construction process is substantially faster, leading to a significant net benefit when both construction and traversal cost are accounted for. Our preliminary results show that current GPU architectures can compete with CPU implementations of hierarchy construction running on multicore systems. In practice, we can construct hierarchies of models with up to several million triangles and use them for fast ray tracing or other applications.
Shape Decomposition using Modal Analysis
Authors: Huang Qi‐Xing , Wicke Martin , Adams Bart , Guibas Leonidas
Published: March 2009

We introduce a novel algorithm that decomposes a deformable shape into meaningful parts requiring only a single input pose. Using modal analysis, we are able to identify parts of the shape that tend to move rigidly. We define a deformation energy on the shape, enabling modal analysis to find the typical deformations of the shape. We then find a decomposition of the shape such that the typical deformations can be well approximated with deformation fields that are rigid in each part of the decomposition. We optimize for the best decomposition, which captures how the shape deforms. A hierarchical refinement scheme makes it possible to compute more detailed decompositions for some parts of the shape.

Although our algorithm does not require user intervention, it is possible to control the process by directly changing the deformation energy, or interactively refining the decomposition as necessary. Due to the construction of the energy function and the properties of modal analysis, the computed decompositions are robust to changes in pose as well as meshing, noise, and even imperfections such as small holes in the surface.
Linear Time Super‐Helices
Authors: Bertails Florence
Published: March 2009

Thin elastic rods such as cables, phone coils, tree branches, or hair, are common objects in the real world but computing their dynamics accurately remains challenging. The recent Super‐Helix model, based on the discrete equations of Kirchhoff for a piecewise helical rod, is one of the most promising models for simulating non‐stretchable rods that can bend and twist. However, this model suffers from a quadratic complexity in the number of discrete elements, which, in the context of interactive applications, makes it limited to a few number of degrees of freedom ‐ or equivalently to a low number of variations in curvature along the mean curve. This paper proposes a new, recursive scheme for the dynamics of a Super‐Helix, inspired by the popular algorithm of Featherstone for serial multibody chains. Similarly to Featherstone's algorithm, we exploit the recursive kinematics of a Super‐Helix to propagate elements inertias from the free end to the clamped end of the rod, while the dynamics is solved within a second pass traversing the rod in the reverse way. Besides the gain in linear complexity, which allows us to simulate a rod of complex shape much faster than the original approach, our algorithm makes it straightforward to simulate tree‐like structures of Super‐Helices, which turns out to be particularly useful for animating trees and plants realistically, under large displacements.
Wrinkling Captured Garments Using Space‐Time Data‐Driven Deformation
Authors: Popa T. , Zhou Q. , Bradley D. , Kraevoy V. , Fu H. , Sheffer A. , Heidrich W.
Published: March 2009

The presence of characteristic fine folds is important for modeling realistic looking virtual garments. While recent garment capture techniques are quite successful at capturing the low‐frequency garment shape and motion over time, they often fail to capture the numerous high‐frequency folds, reducing the realism of the reconstructed space‐time models. In our work we propose a method for reintroducing fine folds into the captured models using data‐driven dynamic wrinkling. We first estimate the shape and position of folds based on the original video footage used for capture and then wrinkle the surface based on those estimates using space‐time deformation. Both steps utilize the unique geometric characteristics of garments in general, and garment folds specifically, to facilitate the modeling of believable folds. We demonstrate the effectiveness of our wrinkling method on a variety of garments that have been captured using several recent techniques.