Time series prediction
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In the year 2010 a continual radon measurement was established at Mladeč Caves in the Czech Republic using a continual radon monitor RADIM3A. In order to model radon time series in the years 2010-15, the Box-Jenkins Methodology, often used in econometrics, was applied. Because of the behavior of radon concentrations (RCs), a seasonal integrated, autoregressive moving averages model with exogenous variables (SARIMAX) has been chosen to model the measured time series. This model uses the time series seasonality, previously acquired values and delayed atmospheric parameters, to forecast RC. The developed model for RC time series is called regARIMA(5,1,3). Model residuals could be retrospectively compared with seismic evidence of local or global earthquakes, which occurred during the RCs measurement. This technique enables us to asses if continuously measured RC could serve an earthquake precursor.
- MeSH
- analýza přerušované časové série MeSH
- jeskyně MeSH
- monitorování radiace metody MeSH
- prediktivní hodnota testů MeSH
- radioaktivní látky znečišťující půdu analýza MeSH
- radon analýza MeSH
- roční období MeSH
- zemětřesení * MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
There has recently been increasing interest in neutral models of biodiversity and their ability to reproduce the patterns observed in nature, such as species abundance distributions. Here we investigate the ability of a neutral model to predict phenomena observed in single-population time series, a study complementary to most existing work that concentrates on snapshots in time of the whole community. We consider tests for density dependence, the dominant frequencies of population fluctuation (spectral density) and a relationship between the mean and variance of a fluctuating population (Taylor's power law). We simulated an archipelago model of a set of interconnected local communities with variable mortality rate, migration rate, speciation rate, size of local community and number of local communities. Our spectral analysis showed 'pink noise': a departure from a standard random walk dynamics in favor of the higher frequency fluctuations which is partly consistent with empirical data. We detected density dependence in local community time series but not in metacommunity time series. The slope of the Taylor's power law in the model was similar to the slopes observed in natural populations, but the fit to the power law was worse. Our observations of pink noise and density dependence can be attributed to the presence of an upper limit to community sizes and to the effect of migration which distorts temporal autocorrelation in local time series. We conclude that some of the phenomena observed in natural time series can emerge from neutral processes, as a result of random zero-sum birth, death and migration. This suggests the neutral model would be a parsimonious null model for future studies of time series data.
In this comparative study, six causality detection methods were compared, namely, the Granger vector autoregressive test, the extended Granger test, the kernel version of the Granger test, the conditional mutual information (transfer entropy), the evaluation of cross mappings between state spaces, and an assessment of predictability improvement due to the use of mixed predictions. Seven test data sets were analyzed: linear coupling of autoregressive models, a unidirectional connection of two Hénon systems, a unidirectional connection of chaotic systems of Rössler and Lorenz type and of two different Rössler systems, an example of bidirectionally connected two-species systems, a fishery model as an example of two correlated observables without a causal relationship, and an example of mediated causality. We tested not only 20000 points long clean time series but also noisy and short variants of the data. The standard and the extended Granger tests worked only for the autoregressive models. The remaining methods were more successful with the more complex test examples, although they differed considerably in their capability to reveal the presence and the direction of coupling and to distinguish causality from mere correlation.
- MeSH
- časové faktory MeSH
- kauzalita MeSH
- systémová analýza MeSH
- teoretické modely * MeSH
- Publikační typ
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Východiska: Časový faktor hraje v radioterapii klíčovou roli. Celková doba trvání radioterapie patří mezi významné prediktivní faktory efektu radioterapie a je spojena s lepší lokální kontrolou i vlivem na přežití pacientů. Důležitou roli má též délka období od stanovení diagnózy k radikální radioterapii či od operace k zahájení radioterapie nebo využití alternativních frakcionačních schémat zkracujících celkovou dobu léčby. Zásadním a dobře proveditelným způsobem aplikace časového faktoru v radioterapii zůstává zejména zamezení prodloužení ozařovací série. Cíl: K přerušení radioterapie většinou dochází z technických důvodů, kvůli faktorům na straně pacienta nebo z personálních důvodů pracoviště. Standardní postupy pro kompenzaci pauzy v léčbě jsou součástí léčebných standardů radioterapeutických pracovišť. Rozvaha o závažnosti možných dopadů přerušení radioterapie a o nutnosti kompenzovat pauzu v léčbě probíhá na podkladě typu a rozsahu onemocnění, léčebného záměru a celkového stavu pacienta. Pacienti jsou zařazeni do tří kategorií dle uvedených parametrů a z nich plynoucího rizika snížení efektu radioterapie z důvodu přerušení léčby. Kompenzaci pauzy v radioterapii provádíme pomocí výpočtu ekvivalentní dávky k normofrakcionaci (EQD2), přičemž je preferován způsob kompenzace umožňující dodržení plánované celkové doby radioterapie bez prodloužení. Vždy je nutné zvažovat přínos pro zachování lokální kontroly nádoru a rizika navýšení akutní nebo zejména pozdní toxicity. V současné epidemiologické situaci často dochází k přerušení radioterapie kvůli onemocnění COVID-19 a následně je z důvodu delších pauz v léčbě často nutné u jednoho pacienta kombinovat více způsobů kompenzace přerušení radioterapie.
Background: The time factor plays a key role in radiotherapy. The radiotherapy overall treatment time is one of the most important predictive factors in the treatment effectiveness and is associated with better local control and impact on the overall survival. The length of the time from the diagnosis to radical radiotherapy or from surgery to adjuvant radiotherapy or the use of alternative fractionation schemes shortening the total treatment time also play an important role. The prevention of prolongation of the radiation series remains a fundamental and well feasible way of applying the time factor in radiotherapy. Purpose: Interruption of radiotherapy usually occurs for technical reasons, due to factors at the patient’s side or for personnel reasons of the department. Standard procedures for the compensation for treatment breaks are part of the treatment protocols at radiotherapy departments. Possible risks of the discontinuation of radiotherapy are considered on the basis of the type and extent of the disease, the treatment intent and the condition of the patient, and the need of compensation for a break in the treatment is set. Patients are classified into three categories according to the above mentioned parameters. Compensation for the pause in radiotherapy is performed by calculating the equivalent dose in 2 Gy per fraction (EQD2); the preferred method of compensation is the one which enables observation of the planned total time of radiotherapy without extension. The benefit of local tumor control and the risk of increased acute or especially late toxicity should always be considered. In the current epidemiological situation, radiotherapy is often discontinued for COVID-19, and due to longer breaks in the treatment, it is necessary to combine multiple compensation methods in one patient.
- MeSH
- časové faktory MeSH
- COVID-19 MeSH
- lidé MeSH
- nádory radioterapie MeSH
- pandemie MeSH
- radioterapie * MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
Accurate risk assignment in childhood acute lymphoblastic leukaemia is essential to avoid under- or over-treatment. We hypothesized that time-series gene expression profiles (GEPs) of bone marrow samples during remission-induction therapy can measure the response and be used for relapse prediction. We computed the time-series changes from diagnosis to Day 8 of remission-induction, termed Effective Response Metric (ERM-D8) and tested its ability to predict relapse against contemporary risk assignment methods, including National Cancer Institutes (NCI) criteria, genetics and minimal residual disease (MRD). ERM-D8 was trained on a set of 131 patients and validated on an independent set of 79 patients. In the independent blinded test set, unfavourable ERM-D8 patients had >3-fold increased risk of relapse compared to favourable ERM-D8 (5-year cumulative incidence of relapse 38·1% vs. 10·6%; P = 2·5 × 10-3 ). ERM-D8 remained predictive of relapse [P = 0·05; Hazard ratio 4·09, 95% confidence interval (CI) 1·03-16·23] after adjusting for NCI criteria, genetics, Day 8 peripheral response and Day 33 MRD. ERM-D8 improved risk stratification in favourable genetics subgroups (P = 0·01) and Day 33 MRD positive patients (P = 1·7 × 10-3 ). We conclude that our novel metric - ERM-D8 - based on time-series GEP after 8 days of remission-induction therapy can independently predict relapse even after adjusting for NCI risk, genetics, Day 8 peripheral blood response and MRD.
- MeSH
- akutní lymfatická leukemie krev genetika mortalita MeSH
- dítě MeSH
- hodnocení rizik MeSH
- kojenec MeSH
- lidé MeSH
- míra přežití MeSH
- prediktivní hodnota testů MeSH
- předškolní dítě MeSH
- přežití bez známek nemoci MeSH
- recidiva MeSH
- regulace genové exprese u leukemie * MeSH
- stanovení celkové genové exprese * MeSH
- Check Tag
- dítě MeSH
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- klinické zkoušky MeSH
- multicentrická studie MeSH
- práce podpořená grantem MeSH
- MeSH
- časové faktory MeSH
- lidé MeSH
- longitudinální studie MeSH
- nenasazení léčby MeSH
- prognóza MeSH
- prospektivní studie MeSH
- resuscitační péče * MeSH
- senioři MeSH
- smrt * MeSH
- získávání tkání a orgánů * metody MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- dopisy MeSH
- multicentrická studie MeSH
- práce podpořená grantem MeSH
BACKGROUND: To identify predictors of survival in patients treated with docetaxel chemotherapy for castration-resistant prostate cancer (CRPC). METHODS: We retrospectively analyzed clinical data from 186 patients who underwent docetaxel chemotherapy for CRPC from 2005 to 2016 at a single center. Pretreatment baseline variables including demographic and clinicopathological data were reviewed. Disease progression was defined by imaging and/or consecutive prostate-specific antigen (PSA) elevation. The systemic immune-inflammation index (SII), the modified Glasgow Prognostic Score (mGPS), and the neutrophil-lymphocyte ratio (NLR) were calculated. Univariable and multivariable Cox proportional hazards regression analyses reporting hazard ratios assessed the risk for disease progression and overall survival (OS). A survival nomogram was constructed. RESULTS: Most patients (n = 139, 74.7%) completed at least 6 cycles of docetaxel chemotherapy. 156 patients (82.9%) experienced disease progression during the studied period. Only mGPS was independently associated with disease progression in a multivariable model (P < 0.01). During the studied period, 98 patients (52.1%) died. The built survival nomogram included statistically significant variables for OS in univariable analysis: hemoglobin, PSA, alkaline phosphatase (AP), lactate dehydrogenase, SII, neutrophil-lymphocyte ratio, mGPS, and site of metastases; and had a concordance index of 0.703. At decision curve analysis, the nomogram led to superior outcomes for any decision associated with a threshold probability of above 40%. In multivariable analysis, only AP (P = 0.02), hemoglobin and PSA (P < 0.01, respectively) remained associated with OS. CONCLUSIONS: PSA, AP, and hemoglobin are independent prognosticators for OS. Although mGPS is a promising marker for tumor progression and SII is a plausible prognostic marker for OS, valid integration of inflammatory indices into a prognostic model requires validation studies. Predictive and prognostic biomarkers are desperately needed to guide physicians in treatment counseling given the heterogeneous nature of CRPC and the plethora of effective therapies.
- MeSH
- časové faktory MeSH
- docetaxel terapeutické užití MeSH
- lidé středního věku MeSH
- lidé MeSH
- míra přežití MeSH
- nádory prostaty rezistentní na kastraci farmakoterapie mortalita MeSH
- prognóza MeSH
- protinádorové látky terapeutické užití MeSH
- retrospektivní studie MeSH
- senioři MeSH
- statistické modely MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- Publikační typ
- časopisecké články MeSH
Úvod a cíl: S100B protein a neuron specifická enoláza (NSE) jsou intenzivně zkoumané markery poškození CNS. Ověření referenční hodnot v séru a variability výsledků na čase odběru, pohlaví a věku jsou základní podmínky interpretace měřených hodnot. Matriál a metoda: Referenční interval jsme ověřili na 50 dobrovolnících, z nichž 10 mělo opakované odběry po 6 a 24 hodinách. Následně jsme analyzovali vliv věku, pohlaví, doby odběru na referenční meze, která byly stanoveny jako 95% percentil referenční skupiny. Výsledky a závěr: Zjistili jsem, že hodnoty NSE a S100B nevykazují klinicky významnou závislost na době odběru, pohlaví a věku. Hodnoty NSE mají vyšší variabilitu výsledků a cca 8 % vzorků muselo být vyloučeno z analýzy pro viditelnou hemolýzu. U S100B proteinu jsme zjistili vyšší horní referenční limit 0,2 μg/l, než je udávaný výrobcem; to však nemá zásadní klinický dopad na hodnocení výsledků.
Objective: S100B protein and neuron specific enolase (NSE) are nowadays intensively investigated as markers of central nervous system damage. Verification of reference values and result variability (biological) are basic conditions of results interpretation. Material and Methods: Reference intervals were verified on 50 volunteers, from them 10 had done repeatedly blood sampling after 6 and 24 hours from baseline. The influence of age, sex and time of sampling on reference cut offs were than analysed. Cut-offs were established as 95% percentile of marker level in analysed group. Results and conclusion: We found that, NSE and S100B levels do not show any clinically important dependence on the time of sampling, age and sex. NSE levels appear to have higher result variability and approximately 8% of samples had to be excluded from analysis due to visible haemolysis. We established a higher reference cut off for S100B – 0.2 μg/l, than manufacturer had set up, but it did not have any crucial effect on clinical evaluation of results.
The mathematical prediction of cell proliferation in porous scaffold still remains a challenge. The analysis of existing models and experimental data confirms a need for a new solution, which takes into account cells" development on the scaffold pore walls as well as some additional parameters such as the pore size, cell density in cellular layers, the thickness of the growing cell layer and others. The simulations, presented below, are based on three main approaches. The first approach takes into account multilayer cell growth on the pore walls of the scaffold. The second approach is a simulation of cell proliferation in a discrete process as a continuous one. The third one is the representation of scaffold structure as a system of cylindrical channels. Oxygen (nutrient) mass transfer is realized inside these channels. The model, described below, proposes the new solution to time dependent description of cell proliferation in porous scaffold and optimized trophical conditions for tissue development.
BACKGROUND AND OBJECTIVE: The not quite rare occurrence of inaccurate clinical diagnoses of burns in early post-burn days leads to an inappropriate conservative treatment strategy, or unnecessary surgery. LDI (Laser Doppler Imaging) objectively evaluates skin blood circulation, which correlates with the depth of the burn and the length of healing. The aim of this work was to suggest cutoff values for detecting burns without healing potential within 3 weeks, which should have undergone surgery. METHOD: The burned area's average blood perfusion of 148 burns was measured on 115 patients, using the Laser Doppler Imager PIM III. A total of 268 measurements were performed from the one to the ninth post-burn day (PBD). The perfusion values were compared to the healing time or histology in the case of the surgical treatment. Cutoff values indicating surgery were investigated in various post-burn days; the ROC analysis was used. RESULTS: This work suggest statistically significant increasing cutoff values for indication to surgery (P = 0.05). From the third to the fifth day 148.5 perfusion units (PU), from the sixth to the seventh day 186.0 PU, from the eighth to the ninth PBD 269.5 PU. The cutoff value is not possible to establish until the second day. CONCLUSION: LDI is a useful method for wound healing prediction and an indication of the necessity of surgery. We have demonstrated that the diagnosis of the healing capacity of LDI needs to take into account the factor of time.
- MeSH
- čas zasáhnout při rozvinutí nemoci MeSH
- časové faktory MeSH
- dítě MeSH
- dospělí MeSH
- hojení ran MeSH
- laser doppler flowmetrie * MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- popálení diagnóza chirurgie MeSH
- prediktivní hodnota testů MeSH
- předškolní dítě MeSH
- prospektivní studie MeSH
- ROC křivka MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- výběr pacientů MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- pozorovací studie MeSH
- práce podpořená grantem MeSH
