scholarly journals INFLUENCE OF BREAKER TYPE ON SURF ZONE DYNAMICS

1986 ◽  
Vol 1 (20) ◽  
pp. 69
Author(s):  
A.S. Arcilla ◽  
A. Vidaor ◽  
J.L. Monso
Keyword(s):  
Surf Zone ◽  
Laboratory Data ◽  
Dynamic State ◽  
Large Set ◽  
Longshore Current ◽  
Stochastic Forcing ◽  
Wave Energy Dissipation ◽  
The Mean ◽  
Definition Of ◽  
Empirical Coefficients

Two of the most significant variables for surf zone hydrodynamic analyses are the mean rate of wave energy dissipation, D, and the longshore current velocity, VI . A detailed theoretical model is extremely difficult to establish (definition of bottom and free surface boundaries, stochastic forcing terms, intense turbulent mixing, etc). The type and amount of existing measured values (laboratory and field) also preclude any accurate calibration, particularly for the more complex formulations. The paper, therefore, presents an average (cross-shore) comparison among state-of-the-art models for D and VI. This illustrates the dependence of these variables on the surf zone dynamic state (closely related to the beach stage, (Short, 1978)), characterized by Iribarren's parameter, ir. Well defined relationships with Ir are obtained for these variables. An expansion of the range of validity of certain models is also attained by calibration of their characteristic free parameters as functions of Ir using a large set of field and laboratory data, and by comparing their general expresion with that of (Losada and S.Arcllla, 1985), which does not include any free parameter. Therefore, theoretical laws for D and VI as simple functions of beach, wave and dynamic state parameters are presented, together with an improved estimation of the empirical coefficients appearing in the various models, suitable for prediction in all ranges of Ir, even though data on the collapsing-surging range are scarce and should require further calibration.

scholarly journals TOWARD AN IMPROVED EMPIRICAL FORMULA FOR LONGSHORE SAND TRANSPORT

1988 ◽  
Vol 1 (21) ◽  
pp. 88 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Kathryn J. Gingerich ◽  
Julie Dean Rosati
Keyword(s):  
Oscillatory Flow ◽  
Field Experiments ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Longshore Current ◽  
Wave Energy Dissipation ◽  
Total Transport ◽  
Local Wave ◽  
Correction Terms

This paper presents results of two field experiments performed using portable traps to obtain point measurements of the longshore sand transport rate in the surf zone. The magnitude of the transport rate per unit width of surf zone is found to depend on the product of the local wave height and mean longshore current speed, but correlation is much improved by including two correction terms, one accounting for local wave energy dissipation and the other for the fluctuation in the longshore current. The field transport rates are also found to be compatible with laboratory rates obtained under combined unidirectional and oscillatory flow. Total transport rates previously reported for this experiment program are revised with recently determined sand trapping efficiencies.

scholarly journals Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade Periprosthetic Joint Infection? A Prospective Study

2019 ◽  
Author(s):  
André Busch ◽  
Marcus Jäger ◽  
Harald Engler ◽  
Marcel Haversath ◽  
Charlotte Bielefeld ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Laboratory Data ◽  
Joint Fluid ◽  
Low Grade ◽  
Synovial Joint ◽  
Knee Infection ◽  
The Mean ◽  
Definition Of

Abstract Background: Since a „gold-standard“ is missing, diagnosing periprosthetic joint infection (PJI) remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (S-PCT and SF-PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection. Methods: Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. S-PCT levels were quantified under the use of immunoassay (Centaur, Siemens, Germany). SF- PCT levels were measured using a standard quantitative PCT enzyme immunoassay kit, according to the manufacturers' instructions (Anti-Procalcitonin antibody ab166963, ABCAM, Cambridge,UK). Results: Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of S-PCT were significantly (p<0.001) higher than those in the aseptic group (PJI 0.05 ng/mL (0.0-1.03) vs. aseptic 0.02 ng/mL (0.0-0.18)). In synovial fluid, the mean PCT values in the aseptic group were significantly higher (p<0.001) than those of PJI group (PJI 2.7 ng/mL (0.53-9.7) vs. aseptic 8.7 ng/mL (0.25-87.9)). S- PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specifity of 91.0%. SF-PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specifity of 52.0%. Conclusion: S-PCT and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

scholarly journals Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade Periprosthetic Joint Infection? A Prospective Study

2020 ◽  
Author(s):  
André Busch ◽  
Marcus Jäger ◽  
Harald Engler ◽  
Marcel Haversath ◽  
Charlotte Bielefeld ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Laboratory Data ◽  
Joint Fluid ◽  
Low Grade ◽  
Synovial Joint ◽  
Knee Infection ◽  
The Mean ◽  
Definition Of

Abstract Background: Since a „gold-standard“ is missing, diagnosing periprosthetic joint infection (PJI) remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (S-PCT and SF-PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection. Methods: Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. S-PCT and SF-PCT levels were measured using standard quantitative PCT enzyme immunoassays. Results: Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of S-PCT were significantly (p<0.001) higher in the PJI group than those in the aseptic group (PJI 0.05 ng/mL ± 0.21 (0.0-1.03) vs. aseptic 0.02 ng/mL ± 0.03 (0.0-0.18)). In synovial fluid, the mean PCT values in the aseptic group were significantly higher (p<0.001) than those of PJI group (PJI 2.7 ng/mL ± 1.4 (0.53-9.7) vs. aseptic 8.7 ng/mL ± 2.5 (0.25-87.9)). S- PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specificity of 91.0%. SF-PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specificity of 52.0%. Conclusion: S-PCT and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

scholarly journals CURRENTS IN THE SURF ZONE

2000 ◽  
Vol 1 (2) ◽  
pp. 3 ◽  
Author(s):  
D. L. Inman ◽  
W. H. Quinn
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Velocity Distribution ◽  
Surf Zone ◽  
Longshore Current ◽  
Mean Velocity ◽  
Single Observation ◽  
Bottom Currents ◽  
Longshore Currents ◽  
The Mean

Surface and bottom currents in the surf zone were measured at 15 equally spaced points along two straight beaches with approximately parallel bottom contours. The measurements showed that offshore currents predominate over onshore currents at the bottom, while at the surface there is a slight predominance in the onshore direction. With regard to the longshore component, it was found that surface and bottom currents have a similar velocity distribution. The variability of the longshore component as measured by its standard deviation is equal to or larger than the mean longshore velocity. This wide variation in longshore currents indicates the impracticability of estimating the mean velocity from a single observation of longshore current. It was found that the momentum approach to the prediction of longshore currents by Putnam, Munk and Traylor (1949) leads to useful forecasts provided the beach friction coefficient k is permitted to vary with the longshore velocity, V. The indicated relation is k~v^(-3/2).

scholarly journals Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade Periprosthetic Joint Infection? A Prospective Study

2020 ◽  
Author(s):  
André Busch ◽  
Marcus Jäger ◽  
Harald Engler ◽  
Marcel Haversath ◽  
Charlotte Bielefeld ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Laboratory Data ◽  
Joint Fluid ◽  
Low Grade ◽  
Synovial Joint ◽  
Knee Infection ◽  
The Mean ◽  
Definition Of

Abstract Background: Since a „gold-standard“ is missing, diagnosing periprosthetic joint infection (PJI) remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (S-PCT and SF-PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection.Methods:Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. S-PCT and SF-PCT levels were measured using standard quantitative PCT enzyme immunoassays.Results: Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of S-PCT were significantly (p<0.001) higher in the PJI group than those in the aseptic group (PJI 0.05 ± 0.21 ng/mL (0.0-1.03) vs. aseptic 0.02 ± 0.03 ng/mL (0.0-0.18)). In synovial fluid, the mean PCT values in the aseptic group were significantly higher (p<0.001) than those of PJI group (PJI 2.7 ± 1.4 ng/mL (0.53-9.7) vs. aseptic 8.7 ± 2.5 ng/mL (0.25-87.9)). S- PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specificity of 91.0%.SF-PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specificity of 52.0%.Conclusion: S-PCT and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

scholarly journals Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade Periprosthetic Joint Infection? A Prospective Study

2020 ◽  
Author(s):  
André Busch ◽  
Marcus Jäger ◽  
Harald Engler ◽  
Marcel Haversath ◽  
Charlotte Bielefeld ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Laboratory Data ◽  
Joint Fluid ◽  
Low Grade ◽  
Synovial Joint ◽  
Knee Infection ◽  
The Mean ◽  
Definition Of

Abstract Background: Since a „gold-standard“ is missing, diagnosing periprosthetic joint infection (PJI) remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (S-PCT and SF-PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection. Methods: Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. S-PCT and SF-PCT levels were measured using standard quantitative PCT enzyme immunoassays. Results: Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of S-PCT were significantly (p<0.001) higher in the PJI group than those in the aseptic group (PJI 0.05 ng/mL ± 0.21 (0.0-1.03) vs. aseptic 0.02 ng/mL ± 0.03 (0.0-0.18)). In synovial fluid, the mean PCT values in the aseptic group were significantly higher (p<0.001) than those of PJI group (PJI 2.7 ng/mL ± 1.4 (0.53-9.7) vs. aseptic 8.7 ng/mL ± 2.5 (0.25-87.9)). S- PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specificity of 91.0%. SF-PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specificity of 52.0%. Conclusion: S-PCT and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

scholarly journals Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade Periprosthetic Joint Infection? A Prospective Study

2019 ◽  
Author(s):  
André Busch ◽  
Marcus Jäger ◽  
Harald Engler ◽  
Marcel Haversath ◽  
Charlotte Bielefeld ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Laboratory Data ◽  
Joint Fluid ◽  
Low Grade ◽  
Synovial Joint ◽  
Mean Values ◽  
The Mean ◽  
Definition Of

Abstract Background Since a „gold-standard“ is missing, diagnosing periprosthetic joint infection remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection.Methods Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. Serum PCT levels were quantified under the use of immunoassay (Centaur, Siemens, Germany). Synovial PCT levels were measured using a standard quantitative PCT enzyme immunoassay kit, according to the manufacturers' instructions (Anti-Procalcitonin antibody ab166963, ABCAM, Cambridge,UK).Results Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of serum PCT was significantly (p<0.001) higher than those in the aseptic group (PJI 0.05 ng/mL (0.0-1.03) vs. aseptic 0.02 ng/mL (0.0-0.18)). In synovial fluid, the mean values in the aseptic group were significantly higher (p<0.001) than those of PJI group (PJI 2.7 ng/mL (0.53-9.7) vs. aseptic 8.7 ng/mL (0.25-87.9)). Serum PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specifity of 91.0%. Synvial fluid PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specifity of 52.0%.Conclusion Serum and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

scholarly journals Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade Periprosthetic Joint Infection? A Prospective Study

2020 ◽  
Author(s):  
André Busch ◽  
Marcus Jäger ◽  
Harald Engler ◽  
Marcel Haversath ◽  
Charlotte Bielefeld ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Periprosthetic Joint Infection ◽  
Joint Infection ◽  
Laboratory Data ◽  
Joint Fluid ◽  
Low Grade ◽  
Synovial Joint ◽  
Knee Infection ◽  
The Mean ◽  
Definition Of

Abstract Background: Since a „gold-standard“ is missing, diagnosing periprosthetic joint infection (PJI) remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (S-PCT and SF-PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection.Methods:Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. S-PCT and SF-PCT levels were measured using standard quantitative PCT enzyme immunoassays.Results: Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of S-PCT were significantly (p<0.001) higher in the PJI group than those in the aseptic group (PJI 0.05 ± 0.21 ng/mL (0.0-1.03) vs. aseptic 0.02 ± 0.03 ng/mL (0.0-0.18)). In synovial fluid, the mean PCT values in the aseptic group were significantly higher (p<0.001) than those of PJI group (PJI 2.7 ± 1.4 ng/mL (0.53-9.7) vs. aseptic 8.7 ± 2.5 ng/mL (0.25-87.9)). S- PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specificity of 91.0%.SF-PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specificity of 52.0%.Conclusion: S-PCT and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

Comparison of Fluorine(18)-fluorodeoxyglucose and Gallium(68)-citrate PET/CT in patients with tuberculosis

2019 ◽  
Vol 58 (05) ◽  
pp. 371-378
Author(s):  
Alfred O. Ankrah ◽  
Ismaheel O. Lawal ◽  
Tebatso M.G. Boshomane ◽  
Hans C. Klein ◽  
Thomas Ebenhan ◽  
...  
Keyword(s):  
Tracer Uptake ◽  
Pet Ct ◽  
The Mean ◽  
18F Fdg ◽  
Definition Of ◽  
Gallium 68 ◽  
Attending Physician ◽  
Pet Scans ◽  
The Brain

Abstract 18F-FDG and 68Ga-citrate PET/CT have both been shown to be useful in the management of tuberculosis (TB). We compared the abnormal PET findings of 18F-FDG- and 68Ga-citrate-PET/CT in patients with TB. Methods Patients with TB on anti-TB therapy were included. Patients had a set of PET scans consisting of both 18F-FDG and 68Ga-citrate. Abnormal lesions were identified, and the two sets of scans were compared. The scan findings were correlated to the clinical data as provided by the attending physician. Results 46 PET/CT scans were performed in 18 patients, 11 (61 %) were female, and the mean age was 35.7 ± 13.5 years. Five patients also had both studies for follow-up reasons during the use of anti-TB therapy. Thirteen patients were co-infected with HIV. 18F-FDG detected more lesions than 68Ga-citrate (261 vs. 166, p < 0.0001). 68Ga-citrate showed a better definition of intracerebral lesions due to the absence of tracer uptake in the brain. The mean SUVmax was higher for 18F-FDG compared to 68Ga-citrate (5.73 vs. 3.01, p < 0.0001). We found a significant correlation between the SUVmax of lesions that were determined by both tracers (r = 0.4968, p < 0.0001). Conclusion Preliminary data shows 18F-FDG-PET detects more abnormal lesions in TB compared to 68Ga-citrate. However, 68Ga-citrate has better lesion definition in the brain and is therefore especially useful when intracranial TB is suspected.

scholarly journals The Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) Study—Defining a Threshold for Non-Cycloplegic Myopia Prevalence in Children

2021 ◽  
Vol 10 (6) ◽  
pp. 1215
Author(s):  
Aparna Gopalakrishnan ◽  
Jameel Rizwana Hussaindeen ◽  
Viswanathan Sivaraman ◽  
Meenakshi Swaminathan ◽  
Yee Ling Wong ◽  
...  
Keyword(s):  
Open Field ◽  
Tamil Nadu ◽  
Mean Difference ◽  
School Vision ◽  
Elite School ◽  
Prevalence Estimates ◽  
The Mean ◽  
Clinically Significant ◽  
Set Up ◽  
Definition Of

The aim of this study was to investigate the agreement between cycloplegic and non-cycloplegic autorefraction with an open-field auto refractor in a school vision screening set up, and to define a threshold for myopia that agrees with the standard cycloplegic refraction threshold. The study was conducted as part of the Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) study, which investigated the prevalence, incidence, and risk factors for myopia among children in South India. Children from two schools aged 5 to 15 years, with no ocular abnormalities and whose parents gave informed consent for cycloplegic refraction were included in the study. All the children underwent visual acuity assessment (Pocket Vision Screener, Elite school of Optometry, India), followed by non-cycloplegic and cycloplegic (1% tropicamide) open-field autorefraction (Grand Seiko, WAM-5500). A total of 387 children were included in the study, of whom 201 were boys. The mean (SD) age of the children was 12.2 (±2.1) years. Overall, the mean difference between cycloplegic and non-cycloplegic spherical equivalent (SE) open-field autorefraction measures was 0.34 D (limits of agreement (LOA), 1.06 D to −0.38 D). For myopes, the mean difference between cycloplegic and non-cycloplegic SE was 0.13 D (LOA, 0.63D to −0.36D). The prevalence of myopia was 12% (95% CI, 8% to 15%) using the threshold of cycloplegic SE ≤ −0.50 D, and was 14% (95% CI, 11% to 17%) with SE ≤ −0.50 D using non-cycloplegic refraction. When myopia was defined as SE of ≤−0.75 D under non-cycloplegic conditions, there was no difference between cycloplegic and non-cycloplegic open-field autorefraction prevalence estimates (12%; 95% CI, 8% to 15%; p = 1.00). Overall, non-cycloplegic refraction underestimates hyperopia and overestimates myopia; but for subjects with myopia, this difference is minimal and not clinically significant. A threshold of SE ≤ −0.75 D agrees well for the estimation of myopia prevalence among children when using non-cycloplegic refraction and is comparable with the standard definition of cycloplegic myopic refraction of SE ≤ −0.50 D.

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