Tag: statistics

Results Phys. 2021 Feb 19:103913. doi: 10.1016/j.rinp.2021.103913. Online ahead of print.

ABSTRACT

In this paper we consider ant-eating pangolin as a possible source of the novel corona virus (COVID-19) and propose a new mathematical model describing the dynamics of COVID-19 pandemic. Our new model is based on the hypotheses that the pangolin and human populations are divided into measurable partitions and also incorporates pangolin bootleg market or reservoir. First we study the important mathematical properties like existence, boundedness and positivity of solution of the proposed model. After finding the threshold quantity for the underlying model, the possible stationary states are explored. We exploit linearization as well as Lyapanuv function theory to exhibit local stability analysis of the model in terms of the threshold quantity. We then discuss the global stability analyses of the newly introduced model and found conditions for its stability in terms of the basic reproduction number. It is also shown that for certain values of R0 , our model exhibits a backward bifurcation. Numerical simulations are performed to verify and support our analytical findings.

PMID:33623730 | PMC:PMC7892304 | DOI:10.1016/j.rinp.2021.103913

Results Phys. 2021 Feb 19:103976. doi: 10.1016/j.rinp.2021.103976. Online ahead of print.

ABSTRACT

One of the greatest challenges facing the humankind nowadays is to confront that emerging virus, which is the Coronavirus (COVID-19), and therefore all organizations have to unite in order to tackle that the transmission risk of this virus. From this standpoint, the scientific researchers have to find good mathematical models that do describe the transmission of such virus and contribute to reducing it in one way or another, where the study of COVID-19 transmission dynamics by mathematical models is very important for analyzing and controlling this disease propagation. Thus, in the current work, we present a new fractional-order mathematical model that describes the dynamics of COVID-19. In the proposed model, the total population is divided into eight classes, in addition to three compartments used to estimate the parameters and initial values. The effective reproduction number ( R0 ) is derived by next generation matrix (NGM) method and all possible equilibrium points and their stability are investigated in details. We used the reported data (from January 23, 2020, to November 21, 2020) from the National Health Commission (NHC) of China to estimate the parameters and initial conditions (ICs) which suggested for our model. Simulation outcomes demonstrate that the fractional order model (FOM) represents behaviors that follow the real data more accurately than the integer-order model. The current work enhances the recent reported results of Zu et al. published in THE LANCET (doi:10.2139/ssrn.3539669).

PMID:33623732 | PMC:PMC7892305 | DOI:10.1016/j.rinp.2021.103976

Results Phys. 2021 Mar;22:103956. doi: 10.1016/j.rinp.2021.103956. Epub 2021 Feb 18.

ABSTRACT

It is of great curiosity to observe the effects of prevention methods and the magnitudes of the outbreak including epidemic prediction, at the onset of an epidemic. To deal with COVID-19 Pandemic, an SEIQR model has been designed. Analytical study of the model consists of the calculation of the basic reproduction number and the constant level of disease absent and disease present equilibrium. The model also explores number of cases and the predicted outcomes are in line with the cases registered. By parameters calibration, new cases in Pakistan are also predicted. The number of patients at the current level and the permanent level of COVID-19 cases are also calculated analytically and through simulations. The future situation has also been discussed, which could happen if precautionary restrictions are adopted.

PMID:33623733 | PMC:PMC7889458 | DOI:10.1016/j.rinp.2021.103956

Geriatr Orthop Surg Rehabil. 2021 Feb 9;12:2151459321991503. doi: 10.1177/2151459321991503. eCollection 2021.

ABSTRACT

In patients over 65y.o. who were surgically treated for a hip fracture, electrolytes have not been specifically studied as predictors of mortality. The main purpose of this study was to assess whether electrolytes and chronic kidney disease (CKD) stages, evaluated at admission, could represent a pre-operative prognostic factor in this population. Moreover, the role of epidemiological and clinical parameters was analyzed with and without a surgical timing stratification. This retrospective study included 746 patients. For each patient, their age, gender, fracture classification, Hb value, comorbidities, ASA class, chronic kidney disease, creatinine levels, electrolytes and surgical timing were collected. CKD-epi, MDRD, modified MDRD and BIS1 were used to obtain eGFR and CKD stages. All parameters were analyzed individually and in relation to the different surgical timing. Descriptive statistics, Chi-square test and survivability analysis with Kaplan Meier curve were used. In patients with a hip fracture non-significant association with increased mortality was shown for the following variables: Hb value, sodium values, calcium values, CKD stages and creatinine values. Otherwise altered kalemia was associated with a statistically significant increase in mortality as well as male gender, two or more comorbid medical conditions, advanced age (>75 years), higher ASA class. Surgery performed within 72h resulted in a statistically significant reduction in mortality at 6 months and, when performed in 24h-48h, a further reduction at 4 years. Age and ASA class statistically significant increased mortality regardless the surgical timing. Male patients operated after 48h from hospitalization were associated with a statistically significant increase in mortality rate. Two or more comorbidities were related to a statistically significant increased number of deaths when patients were treated after 96h. Altered kalemia values at hospitalization are associated with a statistically significant increase in mortality in patients operated after 72h from admission.

PMID:33623723 | PMC:PMC7876745 | DOI:10.1177/2151459321991503

Vet Surg. 2021 Feb 24. doi: 10.1111/vsu.13594. Online ahead of print.

ABSTRACT

OBJECTIVE: To describe medium-term functional outcome after nail osteosynthesis in feline traumatology and report clinically relevant recommendations for I-Loc angle-stable interlocking nail use in cats.

STUDY DESIGN: Prospective clinical study.

SAMPLE POPULATION: Client-owned cats (n = 29).

METHODS: Consecutive cases with femoral, tibial, or humeral fractures were included. Outcome measures included fracture and surgical procedure description, limb alignment, nail size vs body weight (BW), percentage of nail medullary canal (MC) fill, time to limb function at clinical union (CU), and complications. Descriptive statistics were reported and compared with historical data.

RESULTS: Bone distribution was 53.3% femora, 30% tibiae, and 16.7% humeri. There were six epimetaphyseal and 24 diaphyseal fractures. Overall, 67% of fractures were comminuted. Open reduction and minimally invasive techniques were used in 73% and 27% of cases, respectively. Seventeen I-Loc 3 (cat mean BW 4.4 ± 2.2 kg) and 13 I-Loc 4 (cat mean BW 5.2 ± 1.2 kg) nails were placed with mean MC fill of ≤50%. Average time to CU was 7.2 weeks. At CU, lameness had resolved or was mild in every cat, and all cats ultimately regained full limb function. No major complications were encountered.

CONCLUSION: Because of improved CU times, excellent functional outcomes, and low complication rate, our results provide evidence that I-Loc nails are safe and effective for feline traumatology.

CLINICAL SIGNIFICANCE: The I-Loc may be advantageous for fixation of epimetaphyseal fractures. Because of feline bone specific dimensional constraints, I-Loc 3 is likely appropriate for all feline humeri and most tibiae, while I-Loc 4 is well sized for feline femora.

PMID:33625791 | DOI:10.1111/vsu.13594

J Magn Reson Imaging. 2021 Feb 24. doi: 10.1002/jmri.27542. Online ahead of print.

ABSTRACT

BACKGROUND: Clinical examination and lymphoscintigraphy are the current standard for investigating lymphatic function. Magnetic resonance imaging (MRI) facilitates three-dimensional (3D), nonionizing imaging of the lymphatic vasculature, including functional assessments of lymphatic flow, and may improve diagnosis and treatment planning in disease states such as lymphedema.

PURPOSE: To summarize the role of MRI as a noninvasive technique to assess lymphatic drainage and highlight areas in need of further study.

STUDY TYPE: Systematic review.

POPULATION: In October 2019, a systematic literature search (PubMed) was performed to identify articles on magnetic resonance lymphangiography (MRL).

FIELD STRENGTH/SEQUENCE: No field strength or sequence restrictions.

ASSESSMENT: Article quality assessment was conducted using a bespoke protocol, designed with heavy reliance on the National Institutes of Health quality assessment tool for case series studies and Downs and Blacks quality checklist for health care intervention studies.

STATISTICAL TESTS: The results of the original research articles are summarized.

RESULTS: From 612 identified articles, 43 articles were included and their protocols and results summarized. Field strength was 1.5 or 3.0 T in all studies, with 25/43 (58%) employing 3.0 T imaging. Most commonly, imaging of the peripheries, upper and lower limbs including the pelvis (32/43, 74%), and the trunk (10/43, 23%) is performed, including two studies covering both regions. Imaging protocols were heterogenous; however, T₂ -weighted and contrast-enhanced T₁ -weighted images are routinely acquired and demonstrate the lymphatic vasculature. Edema, vessel, quantity and morphology, and contrast uptake characteristics are commonly reported indicators of lymphatic dysfunction.

DATA CONCLUSION: MRL is uniquely placed to yield large field of view, qualitative and quantitative, 3D imaging of the lymphatic vasculature. Despite study heterogeneity, consensus is emerging regarding MRL protocol design. MRL has the potential to dramatically improve understanding of the lymphatics and detect disease, but further optimization, and research into the influence of study protocol differences, is required before this is fully realized.

LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

PMID:33625795 | DOI:10.1002/jmri.27542

J Magn Reson Imaging. 2021 Feb 24. doi: 10.1002/jmri.27568. Online ahead of print.

ABSTRACT

BACKGROUND: Longitudinal magnetic resonance imaging (MRI) studies have become increasingly important to assess the changes in brain morphology during normal aging and neurodegenerative disorders. However, the reliability of longitudinal morphometric changes has not been fully evaluated.

PURPOSE: To examine the reliability of longitudinal (2-year) changes in brain morphology determined by longitudinal voxel-based morphometry (VBM) in healthy elderly subjects, patients with mild cognitive impairment (MCI), and patients with Alzheimer’s disease (AD).

STUDY TYPE: Retrospective analysis.

SUBJECTS: Twenty-four healthy elderly subjects, 28 MCI patients, and 16 AD patients.

FIELD STRENGTH/SEQUENCE: A 1.5 T, magnetization-prepared rapid gradient-echo.

ASSESSMENT: Longitudinal (2-year) changes in gray matter volume determined by longitudinal VBM processing, and visual assessment of image quality.

STATISTICAL TESTS: Intraclass correlation coefficient (ICC) and Kruskal-Wallis test.

RESULTS: The ICC maps differed among the three groups. The mean ICC was 0.81 overall (0.86 for healthy elderly subjects, 0.75 for MCI patients, and 0.76 for AD patients). The reliability was good to excellent (ICC, 0.60-1.00) for 92% of voxels (99% for healthy elderly subjects, 83% for MCI patients, and 83% for AD patients). The image quality differed significantly among the three groups (P < 0.05).

DATA CONCLUSION: These results indicate that the reliability of longitudinal gray matter volume changes by VBM is good to excellent for most voxels. However, reliability may be affected by the disease, possibly due to differences in head motion during imaging. Evidence Level 3 Technical Efficacy Stage 1.

PMID:33625755 | DOI:10.1002/jmri.27568

Diabetes Obes Metab. 2021 Feb 24. doi: 10.1111/dom.14363. Online ahead of print.

ABSTRACT

AIMS: To explore early effects of dapagliflozin on myocardial function and metabolism in patients with type 2 diabetes without heart failure.

MATERIALS AND METHODS: Patients with type 2 diabetes on metformin treatment were randomized to double-blind 6-week placebo or dapagliflozin 10 mg daily treatment. Investigations included cardiac function and structure with myocardial resonance imaging (MRI); cardiac oxygen consumption, perfusion and efficiency with [¹¹ C]-acetate positron emission tomography (PET); and cardiac and hepatic fatty acid uptake with [¹⁸ F]-FTHA PET, analyzed by ANCOVA as least square means with 95% confidence intervals.

RESULTS: Evaluable patients (placebo: n = 24, dapagliflozin: n = 25; 53% males) had mean age 64.4 years, BMI 30.2 kg/m² , and HbA1c 6.7%. Body weight and HbA1c were significantly decreased by dapagliflozin vs placebo. Dapagliflozin had no effect on myocardial efficiency, but external left ventricular (LV) work -0.095 (-0.145, -0.043) J/g/min, and LV oxygen consumption were significantly reduced -0.30 (-0.49, -0.12) J/g/min by dapagliflozin, but changes were not statistically significant vs changes in placebo group. Change in left atrial maximal volume with dapagliflozin vs placebo was -3.19 (-6.32, -0.07) mL/m² , p = 0.056. Peak global radial strain decreased with dapagliflozin vs placebo, -3.92 (-7.57, -0.28) %, p = 0.035; peak global longitudinal and circumferential strains were unchanged. Hepatic fatty acid uptake was increased by dapagliflozin vs placebo, 0.024 (0.004, 0.044) μmol/g/min, p = 0.018, while cardiac uptake was unchanged.

CONCLUSIONS: This exploratory study indicates reduced heart work but limited effects on myocardial function, efficiency, and cardiac fatty acid uptake, while hepatic fatty acid uptake increased, after 6 weeks treatment with dapagliflozin.

CLINICAL TRIAL REGISTRATION: NCT03387683. This article is protected by copyright. All rights reserved.

PMID:33625777 | DOI:10.1111/dom.14363

Mol Divers. 2021 Feb 24. doi: 10.1007/s11030-021-10181-y. Online ahead of print.

ABSTRACT

Histone deacetylases (HDACs) were highlighted as a novel category of anticancer targets. Several HDACs inhibitors were approved for therapeutic use in cancer treatment. Comparatively, receptor-dependent 4D-QSAR, LQTA-QSAR, is a new approach which generates conformational ensemble profiles of compounds by molecular dynamics simulations at binding site of enzyme. This work describes a receptor-dependent 4D-QSAR studies on hydroxamate-based HDACs inhibitors. The 4D-QSAR model was generated by multiple linear regression method of QSARINS. Leave-N-out cross-validation (LNO) and Y-randomization were performed to analysis of the independent test set and to verify the robustness of the model. Best 4D-QSAR model showed the following statistics: R² = 0.8117, Q²_LOO = 0.6881, Q²_LNO = 0.6830, R²_Pred = 0.884. The results may be used for further virtual screening and design for novel HDACs inhibitors. The receptor dependent 4D-QSAR model was developed for the hydroxamate derivatives as HDAC inhibitors by making use of molecular dynamics simulation to obtain conformational ensemble profile for each compound. The multiple linear regression method was used to generate 4D-QSAR model with the suitable predictive ability and the excellent statistical parameters.

PMID:33625673 | DOI:10.1007/s11030-021-10181-y

Environ Sci Pollut Res Int. 2021 Feb 24. doi: 10.1007/s11356-021-12792-2. Online ahead of print.

ABSTRACT

Precise monitoring of cyanobacteria concentration in water resources is a daunting task. The development of reliable tools to monitor this contamination is an important research topic in water resources management. Indirect methods such as chlorophyll-a determination, cell counting, and toxin measurement of the cyanobacteria are tedious, cumbersome, and often lead to inaccurate results. The quantity of phycocyanin (PC) pigment is considered more appropriate for cyanobacteria monitoring. Traditional approaches for PC estimation are time-consuming, expensive, and require high expertise. Recently, some studies have proposed the application of artificial intelligence (AI) techniques to predict the amount of PC concentration. Nonetheless, most of these researches are limited to standalone modeling schemas such as artificial neural network (ANN), multilayer perceptron (MLP), and support vector machine (SVM). The independent schema provides imprecise results when faced with highly nonlinear systems and data uncertainties resulting from environmental disturbances. To alleviate the limitations of the existing models, this study proposes the first application of a hybrid AI model that integrates the potentials of relevance vector machine (RVM) and flower pollination algorithm (RVM-FPA) to predict the PC concentration in water resources. The performance of the hybrid model is compared with the standalone RVM model. The prediction performance of the proposed models was evaluated at two stations (stations 508 and 478) using different statistical and graphical performance evaluation methods. The results showed that the hybrid models exhibited higher performance at both stations compared to the standalone RVM model. The proposed hybrid RVM-FPA can therefore serve as a reliable predictive tool for PC concentration in water resources.

PMID:33625698 | DOI:10.1007/s11356-021-12792-2