Variance Reduction in Analytical Processes in the Clinical Laboratory by Digital Filtering

1983 ◽  
Vol 20 (3) ◽  
pp. 174-181 ◽  
Author(s):  
R T P Jansen ◽  
P J M Bonants
Keyword(s):  
Variance Reduction ◽  
Clinical Laboratory ◽  
Digital Filtering ◽  
Process Variations ◽  
Mean Value ◽  
Time Varying ◽  
Short Term ◽  
Serum Samples ◽  
Filtering Procedure

A model is postulated describing the fluctuations in analytical chemical processes in the clinical laboratory. In this model the process variations are described by a non-stationary stochastic process with a significant time-varying mean value. Experiments demonstrate a short-term variance within a run and a long-term variance between runs determined by the time-varying mean value. For four different analytical systems used for determining six serum analytes between-run variance was demonstrated to be significantly greater than within-run variance. Based on the model a digital filtering procedure is presented which in each run estimates the process mean and subsequently corrects serum samples for its deviation. Thus significant variance reductions are obtained. The filtering procedure was tested for the determination in inorganic phosphate with a continuous-flow system in an experimental environment.

scholarly journals A SLR Pre-Processing Algorithm Based on Satellite Signature Effect

2021 ◽  
Vol 11 (19) ◽  
pp. 8880
Author(s):  
Bowen Guan ◽  
Cunbo Fan ◽  
Ning An ◽  
Ricardo Cesar Podesta ◽  
Dra Ana Pacheco ◽  
...  
Keyword(s):  
Mean Value ◽  
Observation Data ◽  
Short Term ◽  
Error Sources ◽  
Effect Model ◽  
The Mean ◽  
The Stability ◽  
First Time ◽  
Satellite Signature Effect

As one of the major error sources, satellite signature effect should be reduced or even erased from the distribution of the post-fit residuals to improve the ranging precision. A simulation of satellite signature effect removal process for normal point algorithm is conducted based on a revised model of satellite response, which fully considers the structural and distribution characteristics of retroreflectors. In order to eliminate both long-term and short-term satellite signature effect, a clipping method for SLR data processing is proposed by defining the clipping location as 5.6 mm away from the mean value of the long-term fit residuals to select effective returns for normal points. The results indicate that, compared to normal points algorithm, the RMS per NP of LAGEOS-1 observation data processed by the clipping method is reduced from 62.90 ± 9.9 mm to 56.07 ± 4.69 mm, and the stability of RMS is improved 53%. This study improves the satellite signature effect model and simulates the fluctuation of normal points caused by satellite signature effect for the first time. The new method based on the simulation of satellite signature effect has stronger robustness and applicability, which can further minimize the influence of satellite signature effect on the SLR production and significantly improve the data property.

scholarly journals Time-Varying Network Connectedness of G-7 Economic Policy Uncertainties: A Locally Stationary TVP-VAR Approach

2021 ◽  
Vol 7 (2) ◽  
pp. 47-59
Author(s):  
Onur Polat
Keyword(s):  
Economic Policy ◽  
Global Financial Crisis ◽  
Dynamic Networks ◽  
Time Varying ◽  
Short Term ◽  
Frequency Dependent ◽  
Vector Autoregressive ◽  
Network Connectedness ◽  
The Global Financial Crisis

This work analyzes the frequency-dependent network structure of Economic Policy Uncertainties (EPU) across G-7 countries between January 1998 and April 2021. We implement an approach that builds dynamic networks relying on a locally stationary Time-Varying Parameter-Vector Autoregressive model using Quasi-Bayesian Local Likelihood methods. We compute short-, medium-, and long-term network connectedness of G-7 EPUs over a period covering several economic/financial turmoils. Furthermore, we structure short-term network topologies for the Global Financial Crisis (GFC) and the COVID-19 pandemic periods. Findings of the study indicate amplified interdependencies between G-7 EPUs around well-known economic/geopolitical incidents, frequency-dependent connectedness networks among them, and stronger interdependencies than the medium-, and long-term linkages. Finally, we find that short-term spillovers are not persistent in the long-term for both turmoil periods.

scholarly journals Clinical Risk Factors for Long-term Hospital Stay in Common Patients with coronavirus disease 2019(COVID-19)

2020 ◽  
Author(s):  
Wei Lu ◽  
Junjie Fang ◽  
Bin Chen ◽  
Dan Wu ◽  
Chunyao Yu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Hospital Stay ◽  
Potential Risk ◽  
Clinical Laboratory ◽  
Short Term ◽  
Factors Associated ◽  
Regression Methods ◽  
Potential Risk Factors ◽  
Multivariable Regression

Abstract Background This study aimed to investigate the potential risk factors associated with hospital stay in mild patients with COVID-19. Methods A total of 109 laboratory-confirmed COVID patients with initial common subtype diseased by real-time RT-PCR that meet discharge standards were retrospectively included from January 16 to March 15 of 2020. Baseline demographic, clinical, laboratory examination was extracted from electronic medical records at the first day of admission and compared between short-term hospital stay and long-term hospital stay. Univariable and multivariable logistic regression methods were used to explore the risk factors associated with hospital stay. Results Of 109 COVID-19 patients, 61 patients were short-term stay (≤ 10 days) and 48 patients were long-term stay (> 10 days). The average age of patients in short-term stay were younger than those long-term stay(P = 0.01). Hypertension was the most common comorbidity (34%, 21/61), followed by diabetes (15%,9/61) and Cardiopathy (8%, 5/61). Fever and cough were the typical clinical manifestation in two group. Decreased WBC, Hemoglobin and increased Monocyte, MLR (Monocyte Lymphocyte ratio) and Hypersensitive CRP showed a long-term stay (all P < 0.05). The treatment of Resochin and Human immunoglobulin had a shorter hospital stay. Multivariable regression showed that MLR and CRP on admission were risk factors for predicting the hospital stay, with the HR (hazard ratio 2.03, 1.02–5.39; P = 0.022) and (1.32,1.05–3.24, P = 0.045) respectively. Conclusions The potential risk factors of MLR and CRP may help clinicians to predict the hospital stay of COVID-19 patients.

Representational content determines the long-term dynamics of the CA1 spatial code

2021 ◽  
Author(s):  
Alexandra Keinath ◽  
Coralie-Anne Mosser ◽  
Mark Brandon
Keyword(s):  
Episodic Memory ◽  
Prior Experience ◽  
Representational Content ◽  
Spatial Code ◽  
Time Varying ◽  
Short Term ◽  
Daily Experience ◽  
Neural Ensembles ◽  
Spatial Geometry

Abstract Hippocampal subregion CA1 is thought to support episodic memory by reinstating a stable spatial code. Yet recent experiments have demonstrated that this code is largely unstable on a timescale of days, challenging its presumed function. While these dynamics may indeed reflect homogenous drift within the population, they may alternatively reflect distinct time-varying representational component(s) which coexists alongside other stable components. Here we adjudicate between these possibilities. To this end, we characterized the mouse CA1 spatial code over more than a month of daily experience in an extended geometric morph paradigm. We find that this code is governed by distinct representational components with different long-term dynamics, including stable components representing spatial geometry and prior experience. These components are mediated by separate neural ensembles with similar short-term spatial reliability and precision. Together, these results demonstrate that the long-term dynamics of the CA1 spatial code are defined by representational content, not homogenous drift.

scholarly journals Comparing the effect of cardiac biomarkers on the outcome of normotensive patients with acute pulmonary embolism

2017 ◽  
Vol 87 (1) ◽  
Author(s):  
Yaser Jenab ◽  
Marzieh Pourjafari ◽  
Maryam Sotoudeh ◽  
Masoumeh Lotfi-tokaldany ◽  
Nasrin Etesamifard ◽  
...  
Keyword(s):  
Pulmonary Embolism ◽  
Acute Pulmonary Embolism ◽  
Adverse Outcome ◽  
Mean Value ◽  
Cardiac Biomarkers ◽  
Short Term ◽  
Fatty Acid Binding ◽  
The Mean ◽  
Long Term Mortality

Acute pulmonary embolism (PE) is a cardiovascular challenge with potentially fatal consequences. This study was designed to observe the association of novel cardiac biomarkers with outcome in this setting. In this prospective study, from 86 patients with a confirmed diagnosis of PE, 59 patients met the inclusion criteria (22 men, 37 women; mean age, 63.36±15.04 y).The plasma concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP), growth differentiation factor-15 (GDF-15), heart-type fatty acid-binding protein (H-FABP), tenascin-C, and D-dimer were measured at the time of confirmed diagnosis. The endpoints of the study were defined as the short-term adverse outcome and long-term all-cause mortality. Totally, 11.8% (7/59) of the patients had the short-term adverse outcome. The mean value of logNT-proBNP was 6.40±1.66 pg/ml. Among all the examined biomarkers, only the mean value of logNT-proBNP was significantly higher in the patients with the short-term adverse outcome (7.88±0.67 vs. 6.22± 1.66 pg/ml; OR, 2.359; 95% CI, 1.037 to 5.367; P=0.041). After adjustment, a threefold increase in the short-term adverse outcome was identified (OR, 3.239; 95% CI, 0.877 to 11.967; P=0.078).Overall, 18.64% (11/59) of the patients had expired by the long-term follow-up. Moreover, adjustment revealed an evidence regarding association between increased logNT-proBNP levels and long-term mortality (HR, 2.163; 95%CI, 0.910 to 5.142; P=0.081). Our study could find evidences on association between increased level of NT-proBNP and short-term adverse outcome and/or long-term mortality in PE. This biomarker may be capable of improving prediction of outcome and clinical care in non-high-risk PE.

Distributed Stochastic Power Control for Time-Varying Long-Term and Short-Term Fading Wireless Networks

2007 ◽  
Author(s):  
Mohammed M. Olama ◽  
Seddik M. Djouadi ◽  
Charalambos D. Charalambous ◽  
Samir Sahyoun
Keyword(s):  
Wireless Networks ◽  
Power Control ◽  
Time Varying ◽  
Short Term

scholarly journals Extended experience reveals distinct representational dynamics governing the CA1 spatial code

2021 ◽  
Author(s):  
Alexandra T. Keinath ◽  
Coralie-Anne Mosser ◽  
Mark P. Brandon
Keyword(s):  
Episodic Memory ◽  
Calcium Imaging ◽  
Prior Experience ◽  
Representational Content ◽  
Spatial Code ◽  
Time Varying ◽  
Short Term ◽  
Neural Ensembles ◽  
Free Exploration

SummaryHippocampal subregion CA1 is thought to support episodic memory by reinstating a stable spatial code. However, recent calcium imaging experiments have challenged this presumed function by demonstrated that this code is largely unstable on a timescale of days. This turnover may reflect homogenous drift within the population; alternatively, it may reflect distinct time-varying representational component(s) which coexists alongside other stable components. Here we characterized the mouse CA1 spatial code over more than a month of daily free exploration experience in an extended geometric morph paradigm. We find that this code is governed by distinct representational components with different long-term dynamics, including stable components representing the shape of space and prior experience. These components are mediated by separate neural ensembles with similar short-term spatial reliability and precision. Together, these results demonstrate that the long-term dynamics of the CA1 spatial code are defined by representational content, not homogenous drift.

Long-term studies of Serum Concentrations of reproductively related Steriod Hormones in individual captive Carcharhinids

1992 ◽  
Vol 43 (1) ◽  
pp. 273 ◽  
Author(s):  
LEL Rasmussen ◽  
FL Murru
Keyword(s):  
Steroid Hormones ◽  
Mature Female ◽  
Serum Concentrations ◽  
Carcharhinus Plumbeus ◽  
Short Term ◽  
Serum Samples ◽  
Negaprion Brevirostris ◽  
Serial Serum ◽  
Long Term Studies

Valuable information on maturity and reproductive status can be obtained by the measurement of the concentrations of steroid hormones in the serum of captive carcharhinid sharks. The sharks at Sea World of Florida, Orlando, Florida, include mature females of several species of placental sharks. Serial serum samples from four mature female Carcharhinus plumbeus, one maturing female C. leucas, and one mature and one nearly mature female Negaprion brevirostris were used to determine serum concentrations of 17�-oestradiol, progesterone, testosterone and dihydrotestosterone. The data from these mature placental sharks were then compared with concentrations measured in immature female and male conspecifics and in mature female Eugomphodus taurus (family Odontaspididae). Evidence of repetitive cyclical patterns was obtained from a mature female N. brevirostris. This shark was monitored from June 1988 to July 1990 by means of more than 50 samples that were often obtained at weekly intervals. Concentrations of 17�-oestradiol in the serum of this shark varied in a cyclical fashion, with the highest values obtained in Year 1 (1988-89) being during April (the normal mating season) and those in Year 2 (1989-90) being during June. Concomitant elevations of testosterone concentrations were observed either simultaneously or immediately before or after maximal oestradiol concentrations were noted. Progesterone concentrations were low except for definitive spikes that immediately preceded the maximal concentrations of testosterone and 17�-oestradiol. These periodicities suggest, for placental sharks, that consistently rising oestradiol concentrations may set in motion preovulatory events, that testosterone may be important for the initiation of subsequent ovulatory events, and that transitory elevations of progesterone concentrations may have specific short-term roles. These cyclical changes in the concentrations of steroid hormones observed in captive elasmobranchs support observations of hormone concentrations during reproduction in wild carcharhinids.

scholarly journals Provisional standardization of hepcidin assays: creating a traceability chain with a primary reference material, candidate reference method and a commutable secondary reference material

2019 ◽  
Vol 57 (6) ◽  
pp. 864-872 ◽  
Author(s):  
Laura E. Diepeveen ◽  
Coby M.M. Laarakkers ◽  
Gustavo Martos ◽  
Marta E. Pawlak ◽  
Fatih F. Uğuz ◽  
...  
Keyword(s):  
Reference Material ◽  
Clinical Laboratory ◽  
Isotope Dilution Mass Spectrometry ◽  
Reference Method ◽  
Serum Samples ◽  
Traceability Chain ◽  
Long Term Stability ◽  
Purity Analysis ◽  
Primary Reference

Abstract Background Hepcidin concentrations measured by various methods differ considerably, complicating interpretation. Here, a previously identified plasma-based candidate secondary reference material (csRM) was modified into a serum-based two-leveled sRM. We validated its functionality to increase the equivalence between methods for international standardization. Methods We applied technical procedures developed by the International Consortium for Harmonization of Clinical Laboratory Results. The sRM, consisting of lyophilized serum with cryolyoprotectant, appeared commutable among nine different measurement procedures using 16 native human serum samples in a first round robin (RR1). Harmonization potential of the sRM was simulated in RR1 and evaluated in practice in RR2 among 11 measurement procedures using three native human plasma samples. Comprehensive purity analysis of a candidate primary RM (cpRM) was performed by state of the art procedures. The sRM was value assigned with an isotope dilution mass spectrometry-based candidate reference method calibrated using the certified pRM. Results The inter-assay CV without harmonization was 42.1% and 52.8% in RR1 and RR2, respectively. In RR1, simulation of harmonization with sRM resulted in an inter-assay CV of 11.0%, whereas in RR2 calibration with the material resulted in an inter-assay CV of 19.1%. Both the sRM and pRM passed international homogeneity criteria and showed long-term stability. We assigned values to the low (0.95±0.11 nmol/L) and middle concentration (3.75±0.17 nmol/L) calibrators of the sRM. Conclusions Standardization of hepcidin is possible with our sRM, which value is assigned by a pRM. We propose the implementation of this material as an international calibrator for hepcidin.

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