In the framework of Object Oriented Data Analysis, a permutation approach to the two-sample testing problem for network-valued data is proposed. In details, the present framework proceeds in four ...steps: (i) matrix representation of the networks, (ii) computation of the matrix of pairwise (inter-point) distances, (iii) computation of test statistics based on inter-point distances and (iv) embedding of the test statistics within a permutation test. The proposed testing procedures are proven to be exact for every finite sample size and consistent. Two new test statistics based on inter-point distances (i.e., IP-Student and IP-Fisher) are defined and a method to combine them to get a further inferential tool (i.e., IP-StudentFisher) is introduced. Simulated data shows that tests with our statistic exhibit a statistical power that is either the best or second-best but very close to the best on a variety of possible $ Corresponding author alternatives hypotheses and other statistics. A second simulation study that aims at better understanding which features are captured by specific combinations of matrix representations and distances is presented. Finally, a case study on mobility networks in the city of Milan is carried out. The proposed framework is fully implemented in the R package nevada (NEtwork-VAlued Data Analysis).
Motion capture systems enable in-depth interpretations of human movements based on data from three-dimensional joint angles and moments. Such analyses carry important bearings for evaluation of ...movement control during for instance hop landings among sports-active individuals from a performance perspective but also in rehabilitation. Recent statistical development allows analysis of entire time-series of angle and moment during hops using functional data analysis, but the reliability of such multifaceted data is not established. We used integrated pointwise indices (intra-class correlation, ICC; standard error of measurement, SEM) to establish the test–retest reliability of three-dimensional hip, knee and ankle angle and moment curves during landings of one-leg hop for distance (OLHD) in 23 asymptomatic individuals aged 18–28. We contrasted these findings to reliability of discrete variables extracted at specific events (initial contact, peak value). We extended the calculations of ICC and SEM to handle unbalanced situations (varying number of repetitions) to include all available data. Hip and knee angle curves proved reliable with stable ICC curves throughout the landing, with integrated ICCs ≥ 0.71 for all planes except for knee internal/external rotation (ICC = 0.57). Hip and knee moment curves and ankle angle and moments were less reliable and less stable, particularly in the first ~ 10–25% of the landing (integrated ICCs 0.44–0.57). Curve data were generally not in agreement with the results for discrete event data, thus advocating analysis of curve data which contains more information. To conclude, hip and knee angle curve data during OLHD landings can reliably be evaluated, while moment curves necessitate careful consideration.
Abstract
Summary
With increased generation of high-resolution sequence-based 'Omics' data, detecting statistically significant effects at different genomic locations and scales has become key to ...addressing several scientific questions. IWTomics is an R/Bioconductor package (integrated in Galaxy) that, exploiting sophisticated Functional Data Analysis techniques (i.e. statistical techniques that deal with the analysis of curves), allows users to pre-process, visualize and test these data at multiple locations and scales. The package provides a friendly, flexible and complete workflow that can be employed in many genomic and epigenomic applications.
Availability and implementation
IWTomics is freely available at the Bioconductor website (http://bioconductor.org/packages/IWTomics) and on the main Galaxy instance (https://usegalaxy.org/).
Supplementary information
Supplementary data are available at Bioinformatics online.
Background and Objectives:
Endovascular aneurism repair (EVAR) is a minimally invasive alternative to open surgery for the treatment of abdominal aortic aneurysm. Iodine contrast medium (ICM) is ...considered the gold standard, at the high price of related nephrotoxicity and allergic reactions. Carbon dioxide (CO2) has been suggested as an alternative non-nephrotoxic contrast media agent. We aimed to evaluate the safety and the renal impact of the administration of CO2, compared with ICM in EVAR procedures.
Design, Setting, Participants, and Measurements:
We retrospectively reviewed data of patients who underwent EVAR at the Vascular Surgery Department of the Sant’Orsola Hospital in Bologna. Estimated glomerular filtration rate (eGFR) was evaluated before intervention, immediately after and at 12 months.
Results:
In total, 22 patients received CO2 and low-dose ICM (CO2 Group) and 22 received standard ICM (Control Group), matched for clinical characteristics and renal function at the time of procedure. Pre and post-operative renal function values (eGFR) were compared between the two groups: in the immediate post-operative the group treated with CO2 and low-dose ICM globally showed a slight improvement in renal function (mean eGFR +5.10%±3.2), meanwhile the group treated with standard dose of ICM presented a significant worsening of renal function compared with pre-procedure values (mean eGFR −9.65%±4). Incidence of post-contrast acute kidney injury (PC-AKI) was 9% in the CO2 group vs 27% in the Control group. At 12 months, the renal impairment was significantly greater in the ICM group than in the CO2 group (mean eGFR decrease −19.2%±11.1 and −7.40%±3.5, respectively).
Conclusions:
Administration of either CO2 alone or along with low-dose ICM showed to be safer than full-dose ICM alone, lowering the incidence of PC-AKI in patients undergoing EVAR. Unexpectedly, our study revealed also a significant worsening of renal function in patients treated with standard dose of ICM in 1-year follow-up, introducing the concept that acute renal damage caused by ICM could elicit a chronic injury process that affect long-term renal outcomes.
Clinical Impact
Evaluating the safety and the renal impact of the administration of CO2, compared to Iodinate Contrast Medium, in EVAR procedures represents a first step in order to further tayloring medical procedures on patients characteristics. Our findings can guide the clinicians and surgeons in the procedures choice, not considering only the immediate effect of ICM on renal function but also the potential long-term effects.
Simultaneous inference for functional data in sports biomechanics Pataky Todd Colin; Abramowicz Konrad; Liebl Dominik ...
Advances in statistical analysis : AStA : a journal of the German Statistical Society,
01/2023, Letnik:
107, Številka:
1-2
Journal Article
Recenzirano
The recent sports science literature conveys a growing interest in robust statistical methods to analyze smooth, regularly-sampled functional data. This paper focuses on the inferential problem of ...identifying the parts of a functional domain where two population means differ. We considered four approaches recently used in sports science: interval-wise testing (IWT), statistical parametric mapping (SPM), statistical nonparametric mapping (SnPM) and the Benjamini-Hochberg (BH) procedure for false discovery control. We applied these procedures to both six representative sports science datasets, and also to systematically varied simulated datasets which replicated ten signal- and/or noise-relevant parameters that were identified in the experimental datasets. We observed generally higher IWT and BH sensitivity for five of the six experimental datasets. BH was the most sensitive procedure in simulation, but also had relatively high false positive rates (generally > 0.1) which increased sharply (> 0.3) in certain extreme simulation scenarios including highly rough data. SPM and SnPM were more sensitive than IWT in simulation except for (1) high roughness, (2) high nonstationarity, and (3) highly nonuniform smoothness. These results suggest that the optimum procedure is both signal and noise-dependent. We conclude that: (1) BH is most sensitive but also susceptible to high false positive rates, (2) IWT, SPM and SnPM appear to have relatively inconsequential differences in terms of domain identification sensitivity, except in cases of extreme signal/noise characteristics, where IWT appears to be superior at identifying a greater portion of the true signal.
This paper proposes a novel nonparametric approach to model and reveal differences in the geochemical properties of the soil, when these are described by space–time measurements collected in a ...spatial region naturally divided into two parts. The investigation is motivated by a real study on a space–time geochemical data set, consisting of measurements of potassium chloride pH, water pH, and percentage of organic carbon collected during the growing season in the agricultural and forest areas of a site near Brno (Czech Republic). These data are here modeled as spatially distributed functions of time. A permutation approach is introduced to test for the effect of covariates in a spatial functional regression model with heteroscedastic residuals. In this context, the proposed method accounts for the heterogeneous spatial structure of the data by grounding on a permutation scheme for estimated residuals of the functional model. Here, a weighted least squares model is fitted to the observations, leading to asymptotically exchangeable and, thus, permutable residuals. An extensive simulation study shows that the proposed testing procedure outperforms the competitor approaches that neglect the spatial structure, both in terms of power and size. The results of modeling and testing on the case study are shown and discussed.
Background:
Current guidelines recommend radiocephalic arteriovenous fistula (RCAVF) as a first choice access for hemodialysis, without specific indication for octogenarians .This study was ...undertaken to assess the efficacy of RCAVF in octogenarians compared with younger patients.
Material and methods:
All patients treated by RCAVF from January 2013 to December 2017 were included in a prospective database for a retrospective analysis. Patient demographics, comorbidities, and dialytic treatment data were collected prospectively and compared in patients <80 year-old and ⩾80 years-old. Clinical surveillance was performed during each dialysis session. The main endpoints were primary (PP) and assisted patency (AP).
Results:
Within the study period, a total of 294 RCAVF were analyzed: 245 (83.3%) RCAVF were performed in <80 year-old and 49 (16.7%) ⩾80 years old. The overall PP and AP at 2-year was 69% ± 2% and 73% ± 3%, respectively. Patients ⩾ 80 years-old had a significantly reduced 2-year PP, AP of RCAVF compared with the younger patients: 50% ± 8% and 62% ± 7% versus 73% ± 3% and 75% ± 3%, p = 0.01 and p = 0.03, respectively.
The analysis for possible risk factors for reduction of PP in patients ⩾80 years identified in the central venous catheter(CVC) a predictor of earlier RCAVF failure: HR 3.03(95% CI 1.29–7.13), p = 0.01.Kaplan–Meier curve confirms the reduction of PP in ⩾80 years old patients at 2-year follow-up with previous CVC compared patients without history of CVC: 59% ± 10% versus 24% ± 11%, p = 0.01. A comparison between the two groups was made in order to evaluate the impact of previous history of CVC .In absence of a history of CVC use older patients had a similar 2-year PP compared with younger patients: 59% ± 10% versus 72% ± 4%, p = 0.46. Otherwise, the history of a previous CVC reduced significantly the 2-year PP in ⩾80 years old patients compared the younger: 24% ± 12% versus 75% ± 5%, p = 0.0001.
Conclusions:
Despite lower overall primary and primary assisted patency, RCAVF are associated with satisfactory results also in octogenarians if performed in absence of history of CVC. Under these circumstances RCAVF can be considered a first choice treatment.
Although respiratory failure is the most common feature in coronavirus disease 2019 (COVID-19), abdominal organ involvement is likewise frequently observed. To investigate visceral and thoracic ...circulation and abdominal organ damage in COVID-19 patients.
A monocentric observational study was carried on. In COVID-19 patients affected by acute respiratory distress syndrome (ARDS) (n = 31) or mild pneumonia (n = 60) thoracoabdominal circulation was evaluated using Doppler-ultrasound and computed tomography. The study also included non-COVID-19 patients affected by ARDS (n = 10) or portal hypertension (n = 10) for comparison of the main circulatory changes.
Patients affected by COVID-19 ARDS showed hyperdynamic visceral flow and increased portal velocity, hepatic artery resistance-index, and spleen diameter relative to those with mild-pneumonia (p = 0.001). Splanchnic circulatory parameters significantly correlated with the main respiratory indexes (p < 0.001) and pulmonary artery diameter (p = 0.02). The chest and abdominal vascular remodeling pattern of COVID-19 ARDS patients resembled the picture observed in the PH group, while differed from that of the non-COVID ARDS group. A more severe COVID-19 presentation was associated with worse liver dysfunction and enhanced inflammatory activation; these parameters both correlated with abdominal (p = 0.04) and chest imaging measures (p = 0.03).
In COVID-19 ARDS patients there are abdominal and lung vascular modifications that depict a portal hypertension-like pattern. The correlation between visceral vascular remodeling, pulmonary artery enlargement, and organ damage in these critically ill patients is consistent with a portal hyperlfow-like syndrome that could contribute to the peculiar characteristics of respiratory failure in these patients.
our data suggest that the severity of COVID-19 lung involvement is directly related to the development of a portal hyperflow-like syndrome. These observations should help in defining the need for a closer monitoring, but also to develop dedicated therapeutic strategies.
•COVID-19 is a systemic disease that affect thoracic and abdominal organs•Patients affected by COVID-19 ARDS showed a portal hyperflow-like pattern with hyperdynamic visceral flow.•The correlation between visceral and pulmonary vascular remodeling, and organ damage is consistent with pulmonary hypertension secondary to hyperdynamic flow that could contribute to these patients' peculiar characteristics of respiratory failure
Background:
Arteriovenous fistula (AVF) for hemodialysis integrates outward remodeling with vessel wall thickening in response to drastic hemodynamic changes. Aim of this study is to determine the ...role of Ki67, a well-established proliferative marker, related to AVF, and its relationship with time-dependent histological morphologic changes.
Materials and methods:
All patients were enrolled in 1 year and stratified in two groups: (A) pre-dialysis patients submitted to first AVF and (B) patients submitted to revision of AVF. Morphological changes: neo-angiogenesis (NAG), myointimal thickening (MIT), inflammatory infiltrate (IT), and aneurysmatic fistula degeneration (AD). The time of AVF creation was recorded. A biopsy of native vein in Group A and of arterialized vein in Group B was submitted to histological and immunohistochemical (IHC) analysis. IHC for Ki67 was automatically performed in all specimens. Ki67 immunoreactivity was assessed as the mean number of positive cells on several high-power fields, counted in the hot spots.
Results:
A total of 138 patients were enrolled, 69 (50.0%) Group A and 69 (50.0%) Group B. No NAG or MIT were found in Group A. Seven (10.1%) Group A veins showed a mild MIT. Analyzing the Group B, a moderate-to-severe MIT was present in 35 (50.7%), IT in 19 (27.5%), NAG in 37 (53.6%); AD was present in 10 (14.5%). All AVF of Group B with the exception of one (1.4%) showed a positivity for Ki67, with a mean of 12.31 ± 13.79 positive cells/hot spot (range 0–65). Ki67-immunoreactive cells had a subendothelial localization in 23 (33.3%) cases, a myointimal localization in SMC in 35 (50.7%) cases. The number of positive cells was significantly correlated with subendothelial localization of Ki67 (p = 0.001) and with NA (p = 0.001).
Conclusions:
Native veins do not contain cycling cells. In contrast, vascular cell proliferation starts immediately after AVF creation and persists independently of the time the fistula is set up. The amount of proliferating cells is significantly associated with MIT and subendothelial localization of Ki67-immunoreactive cells, thus suggesting a role of Ki-67 index in predicting AVF failure.
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