Comparison of As-Constructed and As-Designed Flexible Pavement Layer Thicknesses

2003 ◽  
Vol 1853 (1) ◽  
pp. 165-176 ◽  
Author(s):  
Goran Mladenovic ◽  
Y. Jane Jiang ◽  
Olga Selezneva ◽  
Susanne Aref ◽  
Michael Darter
Keyword(s):  
Layer Thickness ◽  
Flexible Pavement ◽  
Target Thickness ◽  
Pavement Performance ◽  
Design Values ◽  
The Mean ◽  
Design Value ◽  
Thickness Deviation ◽  
The Individual ◽  
Distribution Type

Sound pavement design is important for improving pavement performance, but construction is equally critical. Because of variations in pavement construction, the as-constructed pavement layer thickness varies spatially within a pavement section, and the mean constructed pavement layer thickness often deviates from the designed values. The as-constructed pavement layer thicknesses are compared to their design values by using data from the newly constructed flexible pavement sections in the Long-Term Pavement Performance program. First, the distribution type of the mean layer thickness deviation was investigated, and a combined statistical test for skewness and kurtosis showed that the mean thickness deviations may be assumed to be normally distributed for a given layer type and target thickness. Typical thickness deviation summary statistics values were derived to estimate the extent of deviations from the design thicknesses. Second, the analysis showed that elevation thickness data differ from the core examination data. Furthermore, as-constructed layer thickness values were compared to their design values by looking into the percentage of the individual measurements falling into specified ranges from the design values and by using two-sided and one-sided t-tests to compare the mean constructed thicknesses and the design values. The analyses showed that the mean constructed layer thicknesses tend to be above the design value for the thinner layers and below the design value for the thicker layers for the same layer and material type. Results from the study will be useful as inputs for reliability-based design procedures.

Estimation of Pavement Layer Thickness Variability for Reliability-Based Design

2003 ◽  
Vol 1849 (1) ◽  
pp. 156-165 ◽  
Author(s):  
Y. “Jane” Jiang ◽  
Olga Selezneva ◽  
Goran Mladenovic ◽  
Susanne Aref ◽  
Michael Darter
Keyword(s):  
Layer Thickness ◽  
Core Layer ◽  
Pavement Design ◽  
Pavement Performance ◽  
Reliability Based Design ◽  
Thickness Variability ◽  
Design Values ◽  
The Mean ◽  
Thickness Variations ◽  
Distribution Type

Estimating the variability of key pavement design inputs is essential to reliability-based pavement design. The thickness of most pavement layers has a great impact on the outcome of practically all analyses of pavement performance. The within-section layer thickness variability is investigated here, as is the extent of the mean layer thickness deviation from its design thickness. Pavement layer thickness data (elevation and core measurements) from a large number of newly constructed flexible and rigid pavement sections in the Long-Term Pavement Performance (LTPP) program were examined. To determine the distribution type of the thickness data, a combined statistical test for skewness and kurtosis showed that ( a) thickness variations within a layer indicate a normal distribution for 86% of 1,034 layers and ( b) the mean thickness deviations from the design values may be assumed to be normally distributed for a layer having a given type and design thickness. The estimated thickness-within-layer variability values and the estimated typical thickness deviations derived from LTPP data may serve as benchmarks for use in pavement design reliability, construction quality assurance specifications, and other research studies. In addition, statistical comparisons of layer thickness variability indicators were made between the elevation and core layer thickness data to determine whether there are systematic differences between these two measuring methods. These results will be very useful to both researchers and practitioners who develop or use reliability-based pavement design procedures.

scholarly journals Analysis of CBR design value selection methods on flexible pavement design: Colombia case study

2020 ◽  
Vol 9 (2) ◽  
pp. 509
Author(s):  
Otto Mora L. ◽  
Michel Murillo A. ◽  
Tiana Rosania A. ◽  
Abraham Castañeda A. ◽  
Rosa Pinto C. ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Resilient Modulus ◽  
Flexible Pavement ◽  
Pavement Design ◽  
Selection Methods ◽  
Essential Variable ◽  
The Mean ◽  
Design Value ◽  
Criterion Method

A comparative analysis was carried out to observe the variation of a flexible pavement structural thickness, due to the use of different meth-ods to calculate the CBR design value, as an essential variable to estimate the Subgrade Resilient Modulus (Mr) through an empirical corre-lation. The Asphalt Institute Method and the Mean Criterion Method were applied to calculate de Design CBR value of a homogeneous roadway division from a representative track section located in the Bolivar Department, Colombia. As a result, the Design Percentiles of the CBR design unit were expanded for the Asphalt Institute method, thus, allowing the approach of more reliable and safe designs, considering that this method limits the selection percentiles to three traffic levels.  

scholarly journals Effect of variations in layer thickness and resilience modulus on flexible pavement performance

2021 ◽  
Vol 10 (8) ◽  
pp. e42610817466
Author(s):  
Thaís Ferrari Réus ◽  
Heliana Barbosa Fontenele
Keyword(s):  
Layer Thickness ◽  
Design Method ◽  
Flexible Pavement ◽  
Empirical Method ◽  
Performance Criteria ◽  
Pavement Performance ◽  
Layered System ◽  
State Highway ◽  
Pavement Performance Prediction ◽  
Resilience Modulus

A pavement mechanistic-empirical analysis is based on a pre-designed structure checked for required performance criteria. In case the latter are not met, this structure is modified and reprocessed. In this context, analyzing the effect of variations in project parameters on pavement performance prediction subsidizes a better understanding of results provided by computer programs. The objective of this study is to assess the effect of layer thickness and resilience modulus variations on flexible pavement performance. To do so, performance was estimated for the 20th project year through Elastic Layered System Model 5 (ELSYM5) software and American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical method (ME). Using multiple regression models for result adjustment and through statistical assessments on regression coefficients calculated, it can be concluded that pavement lifespan consumption, predicted by simulations on ELSYM5, is sensitive to variations in coating and subbase thickness and in subgrade resilience modulus. For AASHTO ME method, predicted values for distresses were significantly sensitive to variations in coating, base and subbase thickness, and in base and subgrade resilience modulus. Comparing both approaches, it is concluded that ELSYM5 can be a viable alternative to the application of a ME pavement design method.

A Simple Method for the Evaluation of Internal Doses in Nuclear Medicine

1974 ◽  
Vol 13 (02) ◽  
pp. 193-206
Author(s):  
L. Conte ◽  
L. Mombelli ◽  
A. Vanoli
Keyword(s):  
Nuclear Medicine ◽  
Close Agreement ◽  
Whole Body ◽  
Simple Method ◽  
Rapid Estimation ◽  
Absorbed Doses ◽  
The Mean ◽  
The Individual ◽  
Estimation Of Risk

SummaryWe have put forward a method to be used in the field of nuclear medicine, for calculating internally absorbed doses in patients. The simplicity and flexibility of this method allow one to make a rapid estimation of risk both to the individual and to the population. In order to calculate the absorbed doses we based our procedure on the concept of the mean absorbed fraction, taking into account anatomical and functional variability which is highly important in the calculation of internal doses in children. With this aim in mind we prepared tables which take into consideration anatomical differences and which permit the calculation of the mean absorbed doses in the whole body, in the organs accumulating radioactivity, in the gonads and in the marrow; all this for those radionuclides most widely used in nuclear medicine. By comparing our results with dose obtained from the use of M.I.R.D.'s method it can be seen that when the errors inherent in these types of calculation are taken into account, the results of both methods are in close agreement.

SERUM THYROTROPHIN AND THE RESPONSE TO THYROTROPHIN RELEASING HORMONE IN SYMPTOMLESS AUTOIMMUNE THYROIDITIS AND IN BORDERLINE AND OVERT HYPOTHYROIDISM

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg
Keyword(s):  
Autoimmune Thyroiditis ◽  
Elevated Serum ◽  
Mean Value ◽  
Primary Hypothyroidism ◽  
Overt Hypothyroidism ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
The Mean ◽  
The Individual ◽  
Serum Tsh

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.

Quality of Life for Children with Persistent Sinonasal Symptoms

2003 ◽  
Vol 128 (1) ◽  
pp. 17-26 ◽  
Author(s):  
David J. Kay ◽  
Richard M. Rosenfeld
Keyword(s):  
Quality Of Life ◽  
Clinical Care ◽  
Longitudinal Change ◽  
Good Test ◽  
Routine Clinical Care ◽  
Before And After ◽  
The Mean ◽  
The Individual ◽  
Sinonasal Symptoms

OBJECTIVE: The goal was to validate the SN-5 survey as a measure of longitudinal change in health-related quality of life (HRQoL) for children with persistent sinonasal symptoms. DESIGN AND SETTING: We conducted a before and after study of 85 children aged 2 to 12 years in a metropolitan pediatric otolaryngology practice. Caregivers completed the SN-5 survey at entry and at least 4 weeks later. The survey included 5 symptom-cluster items covering the domains of sinus infection, nasal obstruction, allergy symptoms, emotional distress, and activity limitations. RESULTS: Good test-retest reliability ( R = 0.70) was obtained for the overall SN-5 score and the individual survey items ( R ≥ 0.58). The mean baseline SN-5 score was 3.8 (SD, 1.0) of a maximum of 7.0, with higher scores indicating poorer HRQoL. All SN-5 items had adequate correlation ( R ≥ 0.36) with external constructs. The mean change in SN-5 score after routine clinical care was 0.88 (SD, 1.19) with an effect size of 0.74 indicating good responsiveness to longitudinal change. The change scores correlated appropriately with changes in related external constructs ( R ≥ 0.42). CONCLUSIONS: The SN-5 is a valid, reliable, and responsive measure of HRQoL for children with persistent sinonasal symptoms, suitable for use in outcomes studies and routine clinical care.

scholarly journals VARIABILITY OF EVOLUTIONARY RATES OF DNA

Genetics ◽  
1986 ◽  
Vol 113 (4) ◽  
pp. 1077-1091
Author(s):  
John H Gillespie
Keyword(s):  
Dna Sequences ◽  
Significant Excess ◽  
Ergodic Markov Chain ◽  
The Third ◽  
Markov Chain Models ◽  
Rate Of Molecular Evolution ◽  
The Mean ◽  
Nuclear Loci ◽  
The Individual ◽  
Evolution Of Proteins

ABSTRACT A statistical analysis of DNA sequences from four nuclear loci and five mitochondrial loci from different orders of mammals is described. A major aim of the study is to describe the variation in the rate of molecular evolution of proteins and DNA. A measure of rate variability is the statistic R, the ratio of the variance in the number of substitutions to the mean number. For proteins, R is found to be in the range 0.16 < R < 35.55, thus extending in both directions the values seen in previous studies. An analysis of codons shows that there is a highly significant excess of double substitutions in the first and second positions, but not in the second and third or first and third positions. The analysis of the dynamics of nucleotide evolution showed that the ergodic Markov chain models that are the basis of most published formulas for correcting for multiple substitutions are incompatible with the data. A bootstrap procedure was used to show that the evolution of the individual nucleotides, even the third positions, show the same variation in rates as seen in the proteins. It is argued that protein and silent DNA evolution are uncoupled, with the evolution at both levels showing patterns that are better explained by the action of natural selection than by neutrality. This conclusion is based primarily on a comparison of the nuclear and mitochondrial results.

Evaluation of retinal inflammatory biomarkers after intravitreal steroid implant and Ranibizumab injection in diabetic macular edema

2021 ◽  
pp. 112067212110294
Author(s):  
Ilkay Kilic Muftuoglu ◽  
Ecem Onder Tokuc ◽  
Fatma Sümer ◽  
V Levent Karabas
Keyword(s):  
Macular Edema ◽  
Diabetic Macular Edema ◽  
Outer Nuclear Layer ◽  
Plexiform Layer ◽  
Retinal Layer ◽  
Treatment Naïve ◽  
The Mean ◽  
The Individual ◽  
Inflammatory Component

Purpose: To compare the efficacy of intravitreal (IV) ranibizumab (IVR) injection with IV dexamethasone implant (IVDEX) in treatment naive diabetic macular edema (DME) patients with inflammatory component. Materials and methods: Treatment naive DME eyes with subfoveal neurosensorial detachment (SND) and hyperreflective spots (HRS) were treated either three loading doses of IVR (18 eyes) or one dose of IVDEX (19 eyes). Central macular thickness (CMT), height of SND, the number of HRSs scattered on the individual retinal layers and photoreceptor integrity were assessed using spectral domain- optical coherence tomography scans over 3-months follow-up. Results: The mean change in best-corrected visual acuity (BCVA) was −0.11 ± 0.08 logMAR in IVDEX group and −0.04 ± 0.06 logMAR in IVR group at 1-month ( p = 0.011). IVDEX group showed statistically significant more increase in BCVA compared to those receiving IVR injections at 2-months ( p = 0.004) and 3-months ( p = 0.017) visits. Compared to baseline, the number of total HRSs and the number of HRSs at each individual inner retinal layer significantly decreased in both groups at all follow-up visits. However, IVDEX group showed more decrease in the total number of HRSs at 2- and 3-months ( p < 0.001 at 2-months, and p = 0.006 at 3-months) and in the mean number of HRSs located at inner nuclear layer–outer plexiform layer level ( p = 0.016 at 1-month, p < 0.001 at 2-months, and p < 0.001 at 3-months). After treatment, the number of HRSs on the outer nuclear layer showed some non-significant increase in both groups. Conclusion: HRSs tended to migrate from inner retina to the outer retina in DME eyes by treatment. Dexamethasone seemed to be more effective option in such cases with inflammatory component.

scholarly journals Effects of the Carrier Phrase on Word Recognition Performances by Younger and Older Listeners Using Two Stimulus Paradigms

2020 ◽  
Vol 31 (06) ◽  
pp. 412-441 ◽  
Author(s):  
Richard H. Wilson ◽  
Victoria A. Sanchez
Keyword(s):  
Word Recognition ◽  
Target Word ◽  
Speaker Recognition ◽  
Repeated Measures ◽  
Recognition Performance ◽  
Test Word ◽  
Root Mean Square Amplitude ◽  
Repeated Measures Design ◽  
The Mean ◽  
The Individual

Abstract Background In the 1950s, with monitored live voice testing, the vu meter time constant and the short durations and amplitude modulation characteristics of monosyllabic words necessitated the use of the carrier phrase amplitude to monitor (indirectly) the presentation level of the words. This practice continues with recorded materials. To relieve the carrier phrase of this function, first the influence that the carrier phrase has on word recognition performance needs clarification, which is the topic of this study. Purpose Recordings of Northwestern University Auditory Test No. 6 by two female speakers were used to compare word recognition performances with and without the carrier phrases when the carrier phrase and test word were (1) in the same utterance stream with the words excised digitally from the carrier (VA-1 speaker) and (2) independent of one another (VA-2 speaker). The 50-msec segment of the vowel in the target word with the largest root mean square amplitude was used to equate the target word amplitudes. Research Design A quasi-experimental, repeated measures design was used. Study Sample Twenty-four young normal-hearing adults (YNH; M = 23.5 years; pure-tone average [PTA] = 1.3-dB HL) and 48 older hearing loss listeners (OHL; M = 71.4 years; PTA = 21.8-dB HL) participated in two, one-hour sessions. Data Collection and Analyses Each listener had 16 listening conditions (2 speakers × 2 carrier phrase conditions × 4 presentation levels) with 100 randomized words, 50 different words by each speaker. Each word was presented 8 times (2 carrier phrase conditions × 4 presentation levels [YNH, 0- to 24-dB SL; OHL, 6- to 30-dB SL]). The 200 recorded words for each condition were randomized as 8, 25-word tracks. In both test sessions, one practice track was followed by 16 tracks alternated between speakers and randomized by blocks of the four conditions. Central tendency and repeated measures analyses of variance statistics were used. Results With the VA-1 speaker, the overall mean recognition performances were 6.0% (YNH) and 8.3% (OHL) significantly better with the carrier phrase than without the carrier phrase. These differences were in part attributed to the distortion of some words caused by the excision of the words from the carrier phrases. With the VA-2 speaker, recognition performances on the with and without carrier phrase conditions by both listener groups were not significantly different, except for one condition (YNH listeners at 8-dB SL). The slopes of the mean functions were steeper for the YNH listeners (3.9%/dB to 4.8%/dB) than for the OHL listeners (2.4%/dB to 3.4%/dB) and were <1%/dB steeper for the VA-1 speaker than for the VA-2 speaker. Although the mean results were clear, the variability in performance differences between the two carrier phrase conditions for the individual participants and for the individual words was striking and was considered in detail. Conclusion The current data indicate that word recognition performances with and without the carrier phrase (1) were different when the carrier phrase and target word were produced in the same utterance with poorer performances when the target words were excised from their respective carrier phrases (VA-1 speaker), and (2) were the same when the carrier phrase and target word were produced as independent utterances (VA-2 speaker).

The Perennial Problem of Variability In Adenosine Triphosphate (ATP) Tests for Hygiene Monitoring Within Healthcare Settings

2015 ◽  
Vol 36 (6) ◽  
pp. 658-663 ◽  
Author(s):  
Greg S. Whiteley ◽  
Chris Derry ◽  
Trevor Glasbey ◽  
Paul Fahey
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Staphylococcus Epidermidis ◽  
Test Point ◽  
Dilution Series ◽  
Healthcare Settings ◽  
Speed Of Response ◽  
Numerical Scale ◽  
Dilution Step ◽  
The Mean ◽  
The Individual

OBJECTIVETo investigate the reliability of commercial ATP bioluminometers and to document precision and variability measurements using known and quantitated standard materials.METHODSFour commercially branded ATP bioluminometers and their consumables were subjected to a series of controlled studies with quantitated materials in multiple repetitions of dilution series. The individual dilutions were applied directly to ATP swabs. To assess precision and reproducibility, each dilution step was tested in triplicate or quadruplicate and the RLU reading from each test point was recorded. Results across the multiple dilution series were normalized using the coefficient of variation.RESULTSThe results for pure ATP and bacterial ATP from suspensions ofStaphylococcus epidermidisandPseudomonas aeruginosaare presented graphically. The data indicate that precision and reproducibility are poor across all brands tested. Standard deviation was as high as 50% of the mean for all brands, and in the field users are not provided any indication of this level of imprecision.CONCLUSIONSThe variability of commercial ATP bioluminometers and their consumables is unacceptably high with the current technical configuration. The advantage of speed of response is undermined by instrument imprecision expressed in the numerical scale of relative light units (RLU).Infect Control Hosp Epidemiol2015;00(0):1–6

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