Abstract 182: Time is Brain on the Collateral Clock! Collaterals and Reperfusion Determine Tissue Injury

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
David S Liebeskind ◽  
Dezhi Liu ◽  
Nerses Sanossian ◽  
Sunil A Sheth ◽  
Conrad Liang ◽  
...  
Keyword(s):  
Linear Models ◽  
Tissue Injury ◽  
Ischemic Injury ◽  
Realistic Model ◽  
Consecutive Series ◽  
Imaging Data ◽  
Advanced Imaging ◽  
Lesion Growth ◽  
Linear Fit ◽  
The Relationship

Background: The pace of ischemic injury due to stroke may vary due to collaterals and degree of reperfusion. Previous linear models that estimate time is brain have not incorporated individual patient data from advanced imaging such as diffusion-weighted imaging (DWI) and angiographic assessment of collateral grade or reperfusion. We developed a realistic model of ischemic injury using detailed imaging data in a homogenous cohort of isolated M1 middle cerebral artery occlusions. Methods: Retrospective analysis of a consecutive series of isolated M1 occlusions was conducted at an expert core lab. ASITN collateral grade was assessed at baseline and extent of reperfusion after endovascular therapy (EVT) was scored with 3 distinct versions of TICI. A separate imaging expert measured DWI lesion volumes on serial MRI acquired from admission to discharge. Graphical analyses illustrated curves demarcating extent of injury over time, based on both collateral grade and extent of reperfusion. Results: 126 patients (median age 73; 88 women; median NIHSS 17; median time to 1 st DWI, 4h08min) with acute stroke due to M1 occlusion (61 proximal, 65 distal) underwent EVT during a 6-year period. Median collateral grade was 2 (range 0-4) and median TICI, 2B (range 0-3). mTICI scores were 0 (n=18), 1 (6), 2A (25), 2B (73), and 3 (4) with 24 TICI 2C scores when evaluated in detail. Total number of DWI scans was 323, with mean 2.5 per patient. Collateral grade strongly influenced pace of development of initial tissue injury (ASITN 0, 0.445 cc/min; 1, 0.276 cc/min; 2, 0.178 cc/min; 3, 0.106 cc/min; 4, 0.031 cc/min). The relationship between time and DWI lesion growth was not linear, but best fit logarithmically (R 2 = 0.985, RMSE 2.1 for log fit; R 2 = 0.757, RMSE 8.1 for linear fit). Individual lesion growth varied markedly with both collateral grade (ANOVA p<0.001) and the degree (TICI 2B/3 vs. 0,1,2A) of reperfusion (ANOVA p=0.013). Conclusions: Collateral grade and the degree of reperfusion strongly dictate the timecourse of ischemic injury in the brain after stroke onset. Advanced imaging and angiographic assessment of collaterals and reperfusion confirm a logarithmic, not linear, model that can be used to differentiate stroke patients and streamline therapeutic strategies.

A realistic model for transverse shear stiffness prediction of composite corrugated-core sandwich structure with bonding effect

2021 ◽  
pp. 109963622199386
Author(s):  
Tianshu Wang ◽  
Licheng Guo
Keyword(s):  
Present Model ◽  
Shear Stiffness ◽  
Realistic Model ◽  
Torsional Stiffness ◽  
Fem Model ◽  
The Core ◽  
Bonding Effect ◽  
Stiffness Model ◽  
Bonding Area ◽  
The Relationship

In this paper, a shear stiffness model for corrugated-core sandwich structures is proposed. The bonding area is discussed independently. The core is thought to be hinged on the skins with torsional stiffness. The analytical model was verified by FEM solution. Compared with the previous studies, the new model can predict the valley point of the shear stiffness at which the relationship between the shear stiffness and the angle of the core changes from negative correlation to positive correlation. The valley point increases when the core becomes stronger. For the structure with a angle of the core smaller than counterpart for the valley point, the existing analytical formulations may significantly underestimate the shear stiffness of the structure with strong skins. The results obtained by some previous models may be only 10 persent of that of the present model, which is supported by the FEM model.

scholarly journals The Relationships Between Serum DHEA-S and AMH Levels in Infertile Women: A Retrospective Cross-Sectional Study

2021 ◽  
Vol 10 (6) ◽  
pp. 1211
Author(s):  
Li-Te Lin ◽  
Kuan-Hao Tsui
Keyword(s):  
Generalized Linear Models ◽  
Large Scale ◽  
Linear Models ◽  
Positive Association ◽  
Cross Sectional Study ◽  
Dehydroepiandrosterone Sulphate ◽  
Sectional Study ◽  
Cross Sectional ◽  
Infertile Women ◽  
The Relationship

The relationship between serum dehydroepiandrosterone sulphate (DHEA-S) and anti-Mullerian hormone (AMH) levels has not been fully established. Therefore, we performed a large-scale cross-sectional study to investigate the association between serum DHEA-S and AMH levels. The study included a total of 2155 infertile women aged 20 to 46 years who were divided into four quartile groups (Q1 to Q4) based on serum DHEA-S levels. We found that there was a weak positive association between serum DHEA-S and AMH levels in infertile women (r = 0.190, p < 0.001). After adjusting for potential confounders, serum DHEA-S levels positively correlated with serum AMH levels in infertile women (β = 0.103, p < 0.001). Infertile women in the highest DHEA-S quartile category (Q4) showed significantly higher serum AMH levels (p < 0.001) compared with women in the lowest DHEA-S quartile category (Q1). The serum AMH levels significantly increased across increasing DHEA-S quartile categories in infertile women (p = 0.014) using generalized linear models after adjustment for potential confounders. Our data show that serum DHEA-S levels are positively associated with serum AMH levels.

scholarly journals Relationship between Cycling Infrastructure and Transportation Cycling in a Small Urban Area

2021 ◽  
Vol 1 (1) ◽  
pp. 99-112
Author(s):  
Richard Larouche ◽  
Nimesh Patel ◽  
Jennifer L. Copeland
Keyword(s):  
Generalized Linear Models ◽  
Qualitative Data ◽  
Linear Models ◽  
The Other ◽  
Small City ◽  
The Road ◽  
The Past ◽  
Low Prevalence ◽  
The Relationship

The role of infrastructure in encouraging transportation cycling in smaller cities with a low prevalence of cycling remains unclear. To investigate the relationship between the presence of infrastructure and transportation cycling in a small city (Lethbridge, AB, Canada), we interviewed 246 adults along a recently-constructed bicycle boulevard and two comparison streets with no recent changes in cycling infrastructure. One comparison street had a separate multi-use path and the other had no cycling infrastructure. Questions addressed time spent cycling in the past week and 2 years prior and potential socio-demographic and psychosocial correlates of cycling, including safety concerns. Finally, we asked participants what could be done to make cycling safer and more attractive. We examined predictors of cycling using gender-stratified generalized linear models. Women interviewed along the street with a separate path reported cycling more than women on the other streets. A more favorable attitude towards cycling and greater habit strength were associated with more cycling in both men and women. Qualitative data revealed generally positive views about the bicycle boulevard, a need for education about sharing the road and for better cycling infrastructure in general. Our results suggest that, even in smaller cities, cycling infrastructure may encourage cycling, especially among women.

scholarly journals Predicting Rates of Inbreeding in Populations Undergoing Selection

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1851-1864 ◽  
Author(s):  
John A Woolliams ◽  
Piter Bijma
Keyword(s):  
Overlapping Generations ◽  
Linear Models ◽  
Selection Process ◽  
Correction Term ◽  
Random Mating ◽  
Nonrandom Mating ◽  
Selection Processes ◽  
Genetic Contributions ◽  
The Relationship

AbstractTractable forms of predicting rates of inbreeding (ΔF) in selected populations with general indices, nonrandom mating, and overlapping generations were developed, with the principal results assuming a period of equilibrium in the selection process. An existing theorem concerning the relationship between squared long-term genetic contributions and rates of inbreeding was extended to nonrandom mating and to overlapping generations. ΔF was shown to be ~¼(1 − ω) times the expected sum of squared lifetime contributions, where ω is the deviation from Hardy-Weinberg proportions. This relationship cannot be used for prediction since it is based upon observed quantities. Therefore, the relationship was further developed to express ΔF in terms of expected long-term contributions that are conditional on a set of selective advantages that relate the selection processes in two consecutive generations and are predictable quantities. With random mating, if selected family sizes are assumed to be independent Poisson variables then the expected long-term contribution could be substituted for the observed, providing ¼ (since ω = 0) was increased to ½. Established theory was used to provide a correction term to account for deviations from the Poisson assumptions. The equations were successfully applied, using simple linear models, to the problem of predicting ΔF with sib indices in discrete generations since previously published solutions had proved complex.

scholarly journals Bayonet-shaped language development in autism with regression: a retrospective study

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
David Gagnon ◽  
Abderrahim Zeribi ◽  
Élise Douard ◽  
Valérie Courchesne ◽  
Borja Rodríguez-Herreros ◽  
...  
Keyword(s):  
Language Development ◽  
Linear Models ◽  
Autism Spectrum ◽  
Early Language ◽  
Verbal Iq ◽  
Logistic Regression Models ◽  
Language Level ◽  
Language Outcome ◽  
Almost All ◽  
The Relationship

Abstract Background Language delay is one of the major referral criteria for an autism evaluation. Once an autism spectrum diagnosis is established, the language prognosis is among the main parental concerns. Early language regression (ELR) is observed by 10–50% of parents but its relevance to late language level and socio-communicative ability is uncertain. This study aimed to establish the predictive value of ELR on the progression of language development and socio-communicative outcomes to guide clinicians in addressing parents’ concerns at the time of diagnosis. Methods We used socio-communicative, language, and cognitive data of 2,047 autism spectrum participants from the Simons Simplex Collection, aged 4–18 years (mean = 9 years; SD = 3.6). Cox proportional hazard and logistic regression models were used to evaluate the effect of ELR on language milestones and the probability of using complex and flexible language, as defined by the choice of ADOS module at enrollment. Linear models were then used to evaluate the relationship of ELR and non-verbal IQ with socio-communicative and language levels. Results ELR is associated with earlier language milestones but delayed attainment of fluent, complex, and flexible language. However, this language outcome can be expected for almost all autistic children without intellectual disability at 18 years of age. It is mostly influenced by non-verbal IQ, not ELR. The language and socio-communicative level of participants with flexible language, as measured by the Vineland and ADOS socio-communicative subscales, was not affected by ELR. Limitations This study is based on a relatively coarse measure of ultimate language level and relies on retrospective reporting of early language milestones and ELR. It does not prospectively document the age at which language catches up, the relationship between ELR and other behavioral areas of regression, nor the effects of intervention. Conclusions For autistic individuals with ELR and a normal level of non-verbal intelligence, language development follows a “bayonet shape” trajectory: early first words followed by regression, a plateau with limited progress, and then language catch up.

scholarly journals Gender Differences in Phytoestrogens and the Relationship with Speed of Processing in Older Adults: A Cross-Sectional Analysis of NHANES, 1999–2002

Nutrients ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1780 ◽  
Author(s):  
Alwerdt ◽  
Patterson ◽  
Sliwinski
Keyword(s):  
Older Adults ◽  
Gender Differences ◽  
Cognitive Aging ◽  
Linear Models ◽  
Speed Of Processing ◽  
Cross Sectional ◽  
Health And Nutrition ◽  
Performance Results ◽  
Sectional Analysis ◽  
The Relationship

Sex hormone changes in adults are known to play a part in aging, including cognitive aging. Dietary intake of phytoestrogens can mimic estrogenic effects on brain function. Since sex hormones differ between genders, it is important to examine gender differences in the phytoestrogen–cognition association. Therefore, the goal of this study is to examine the relationship between urinary phytoestrogens and speed of processing (SOP) and the variation of the association between genders in older adults. Participants were drawn from the 1999–2002 National Health and Nutrition Examination Survey and included 354 individuals aged 65–85 years old. General linear models (GLMs) were used to test for significant gender differences in the relationship between phytoestrogens and SOP. Results from the GLMs showed significant gender differences in the relationship between genistein and SOP. Higher levels of genistein were associated with better SOP in women. This relationship was reversed in men: higher genistein levels were associated with worse performance. Results indicate that there are distinct gender differences in the relationship between genistein and SOP. These results emphasize the importance of considering gender differences when devising dietary and pharmacologic interventions that target phytoestrogens to improve brain health.

Signaling sustainability: impact that learning how to report has on enrollment, endowment and emissions of North American higher education institutions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marcel C. Minutolo ◽  
Albena Ivanova ◽  
Michelle Cong
Keyword(s):  
Higher Education ◽  
Linear Models ◽  
Higher Education Institutions ◽  
Main Hypothesis ◽  
Signaling Mechanism ◽  
Content Type ◽  
Improved Performance ◽  
And Performance ◽  
Reporting Mechanism ◽  
The Relationship

Purpose The purpose of this paper is to develop an integrated model assessing the frequency and timing between reports on the Association for the Advancement of Sustainability in Higher Education (AASHE) Sustainability Tracking, Assessment and Rating System (STARS) reporting the framework by higher education institutions (HEIs) and the relationship between the STARS score and reputation (enrollment), finances (endowment) and performance (emissions). Design/methodology/approach The development of the theoretical model is based on learning, signaling and legitimacy theories. This study collects data from the AASHE STARS to indicate the rating level of 202 HEIs, control variables, enrollment, endowments and emissions. The hypotheses were tested using generalized linear models. Findings Findings suggest that as HEIs report on their sustainability activity, they learn to report better but that there is also an “un-learning” aspect if the HEI skips reporting in a period. The results support the main hypothesis that there is a relationship between reporting and engagement with the HEIs in the form of enrollment and endowments. Finally, the findings provide evidence that the HEIs’ reporting is associated with a reduction in emissions. Practical implications The findings suggest that HEIs should develop a reporting strategy on a standardized framework such as AASHE STARs and they ought to codify the approach to learn from prior reporting. Students and alumni are increasingly seeking to engage the HEI in the sustainability process and the report is a mechanism for signaling activities. Social implications The findings suggest that AASHE STARS scores may be used by HEIs as a signaling mechanism to stakeholders of their commitment to sustainability. The signal is a mechanism to reduce information asymmetry between the HEI and stakeholders who may want more information on the institution’s attempts toward sustainability but lack access to information. Further, HEI partners have a mechanism to assess the overall level of commitment of the HEI toward sustainability and can, therefore, engage accordingly. Originality/value There has been significant work on signaling theory and sustainability. However, the relationship between STARs reporting as a signal that legitimates the HEI, learning how to report well and HEI performance has received less attention. The current study demonstrates that the STARS framework as a reporting mechanism signals the HEIs’ level of commitment to sustainability thereby legitimating it resulting in improved performance.

Is duodenal biopsy always necessary for the diagnosis of coeliac disease in adult patients with high anti-tissue transglutaminase (TTG) antibody titres?

2021 ◽  
pp. flgastro-2020-101728
Author(s):  
Junaid Beig ◽  
Kamran Rostami ◽  
David T S Hayman ◽  
Summer Hassan ◽  
Stephen Gerred ◽  
...  
Keyword(s):  
Coeliac Disease ◽  
Linear Models ◽  
Tissue Transglutaminase ◽  
Signs And Symptoms ◽  
Duodenal Biopsy ◽  
Adult Patients ◽  
Antibody Titres ◽  
Red Flag ◽  
The Relationship ◽  
Duodenal Biopsies

ObjectiveAvoiding duodenal biopsy in adults for coeliac disease (CD) diagnosis is controversial. Some retrospective and prospective studies have shown that CD can be reliably diagnosed in adults with serology rather than duodenal biopsies. This study aimed to check the accuracy of a cut-off value of ≥10 upper limit of normal of anti-tissue transglutaminase antibody (anti-TTG IgA) titres for CD diagnosis in adult patients.MethodWe retrospectively analysed adult patients (≥16 years) who underwent gastroscopy from 2013 to 2018 for positive coeliac serology. The relationship between titres and disease was determined by using linear models, whereas sensitivity and specificity were assessed by receiver operator curve.ResultsWe analysed 144 newly anti-TTG antibody-positive adult patients with a median age of 48.5 years (IQR 32–62); among them, 86 (60%) patients had CD (Marsh III: n=68 and Marsh II and I: n=18) with a higher prevalence in females (n=59 (69%)) and Europeans (n=60 (70%)). Fifty (58%) patients with CD had colonoscopy and five (6%) had imaging; only six patients were diagnosed with additional conditions. An anti-TTG IgA titre cut-off value of 150 U/L was 100% specific for CD in our dataset, with 70% (95% CI: 60% to 88%) sensitivity for this patient group.ConclusionCoeliac serology using anti-TTG IgA with titres ≥10× normal value is an excellent predictor of CD, irrespective of age, gender and ethnicity. Duodenal biopsy may not be necessary in selected adult patients with CD, especially younger than 50 years of age without additional gastrointestinal red-flag signs and symptoms.

Relationship between plasma osmolality and plasma vasopressin in human subjects

1980 ◽  
Vol 238 (4) ◽  
pp. E313-E317 ◽  
Author(s):  
M. Hammer ◽  
J. Ladefoged ◽  
K. Olgaard
Keyword(s):  
Linear Models ◽  
Human Subjects ◽  
Plasma Osmolality ◽  
Metabolic Clearance ◽  
Parabolic Model ◽  
Pronounced Increase ◽  
Plasma Vasopressin ◽  
Log Linear ◽  
The Relationship ◽  
Best Fit

The relationship between plasma osmolality (pOsm) and plasma vasopressin (pAVP) was studied in 13 human subjects during dehydration. The fit of linear, log-linear, parabolic, and exponential models was tested. For all of the data, the nonlinear models had the best fit. However, when individual differences in either gain or threshold were allowed for, the linear models were better than log-linear models. Finally, analyses were made with individual data points. Linear models had the best fit in half of the subjects, whereas for the others the parabolic model gave the best fit. For those subjects investigated in the low range of the osmoregulatory curve, a linear relationship was found, whereas, for those having the most pronounced increase in pOsm, the most significant improvement was found with the parabolic model. This finding indicates that the relationship is not stable during dehydration in the whole range and that hypovolemia probably can influence the secretion rate and/or metabolic clearance rate and thereby the relationship.

scholarly journals Temporal analysis of the relationship between dengue and meteorological variables in the city of Rio de Janeiro, Brazil, 2001-2009

2012 ◽  
Vol 28 (11) ◽  
pp. 2189-2197 ◽  
Author(s):  
Adriana Fagundes Gomes ◽  
Aline Araújo Nobre ◽  
Oswaldo Gonçalves Cruz
Keyword(s):  
Minimum Temperature ◽  
Rio De Janeiro ◽  
Linear Models ◽  
Negative Binomial ◽  
Critical Factor ◽  
Temporal Analysis ◽  
Temporal And Spatial Distribution ◽  
Temperature And Precipitation ◽  
The Relationship ◽  
The City

Dengue, a reemerging disease, is one of the most important viral diseases transmitted by mosquitoes. Climate is considered an important factor in the temporal and spatial distribution of vector-transmitted diseases. This study examined the effect of seasonal factors and the relationship between climatic variables and dengue risk in the city of Rio de Janeiro, Brazil, from 2001 to 2009. Generalized linear models were used, with Poisson and negative binomial distributions. The best fitted model was the one with "minimum temperature" and "precipitation", both lagged by one month, controlled for "year". In that model, a 1°C increase in a month's minimum temperature led to a 45% increase in dengue cases in the following month, while a 10-millimeter rise in precipitation led to a 6% increase in dengue cases in the following month. Dengue transmission involves many factors: although still not fully understood, climate is a critical factor, since it facilitates analysis of the risk of epidemics.

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