Tag: statistics

Stat Med. 2022 Dec 23. doi: 10.1002/sim.9636. Online ahead of print.

ABSTRACT

In this paper we propose a new robust estimation of precision matrices for high-dimensional data when the number of variables is larger than the sample size. Different from the existing methods in literature, the proposed model combines the technique of modified Cholesky decomposition (MCD) with the robust generalized M-estimators. The MCD reparameterizes a precision matrix and transforms its estimation into solving a series of linear regressions, in which the commonly used robust techniques can be conveniently incorporated. Additionally, the proposed method adopts the model averaging idea to address the ordering issue in the MCD approach, resulting in an accurate estimation for precision matrices. Simulations and real data analysis are conducted to illustrate the merits of the proposed estimator.

PMID:36563324 | DOI:10.1002/sim.9636

Am J Gastroenterol. 2022 Dec 23. doi: 10.14309/ajg.0000000000002088. Online ahead of print.

ABSTRACT

BACKGROUND: Evidence on the comparative diagnostic performance of endoscopic ultrasound (EUS)-based techniques for pancreatic cyst lesions (PCLs) is limited. This network meta-analysis comprehensively compared EUS-based techniques for PCLs diagnosis.

METHODS: A comprehensive literature search was performed for all comparative studies assessing the accuracy of 2 or more modalities for PCLs diagnosis. The primary outcome was the diagnostic efficacy for mucinous PCLs. Secondary outcomes were the diagnostic efficacy for malignant PCLs, diagnostic success rate, and adverse event rate. A network meta-analysis was conducted using the ANOVA model to assess the diagnostic accuracy of each index.

RESULTS: Forty studies comprising 3641 patients were identified. The network ranking of the superiority index for EUS-guided needle-based confocal laser endomicroscopy (EUS-nCLE) and EUS-guided through-the-needle biopsy (EUS-TTNB) were significantly higher than other techniques for differentiating mucinous PCLs; besides, EUS-TTNB was also the optimal technique in identifying malignant PCLs. The evidence was inadequate for EUS-nCLE diagnosing malignant PCLs and CH-EUS for diagnosing both mucinous and malignant PCLs. Glucose showed a high sensitivity but low specificity, and molecular analysis (KRAS, GNAS and KRAS+GNAS mutations) showed a high specificity but low sensitivity for diagnosing mucinous PCLs. Satisfactory results were not obtained during the evaluation of the efficiency of pancreatic cyst fluid (PCF) biomarkers in detecting malignant PCLs.

CONCLUSIONS: For centers with relevant expertise and facilities, EUS-TTNB and EUS-nCLE were better choices for the diagnosis of PCLs. Further studies are urgently required for further improving PCF biomarkers and validating diagnostic performance of the index techniques.

PMID:36563321 | DOI:10.14309/ajg.0000000000002088

Am J Gastroenterol. 2022 Dec 23. doi: 10.14309/ajg.0000000000002118. Online ahead of print.

ABSTRACT

INTRODUCTION: Patency capsule (PC) is a recommended procedure to rule-out small-bowel stenosis before video capsule endoscopy (VCE). We examined future clinical outcomes among patients with failed-PC versus patients in whom PC had passed (passed-PC).

METHODS: A Post-hoc analysis of two prospective cohort studies of adult patients with quiescent small-bowel CD that underwent PC between 2013-2020. The primary composite-outcome was the need for intestinal-surgery or endoscopic-dilation during follow-up in patients with or without failed-PC.

RESULTS: A total of 190 patients were included (47-failed PC, 143-passed PC, median follow-up 34.12 months). Patients with a failed-PC had higher rates of the primary composite-outcome (21.3% vs. 1.4%, Hazard ratio [HR] 20.3, 95% confidence interval [CI] 4.4-93.7, p<0.001) and also secondary outcomes including intestinal-surgery (14.9% vs. 0.70%, p<0.001), endoscopic-dilation (14.9% vs. 0.70%, p<0.001), admissions (23.3% vs. 5.7%, p<0.001) and clinical-flares (43.9% vs. 27.7%, p=0.005) during follow-up compared with controls. Failed-PC was the only statistically significant factor for surgery and/or endoscopic-dilation, regardless of a B2/B3 phenotype at baseline. In sensitivity-analyses restricted only to patients with stricturing phenotype (n=73), failed-PC still predicted worse long-term composite-outcome (HR 8.68 95% CI 1.72-43.68, p=0.002). Of the 190 patients ingesting a PC, only one patient with a failed-PC had 48 hours of self-limiting mild symptoms.

DISCUSSION: Clinically-stable CD patients with failed-PC have worse long-term clinical outcomes than those without, independently of CD phenotype. Standalone PC may serve as a novel, safe and affordable prognostic examination, to identify patients with quiescent CD who have a higher risk for future worse clinical outcomes.

PMID:36563317 | DOI:10.14309/ajg.0000000000002118

Am J Gastroenterol. 2022 Dec 22. doi: 10.14309/ajg.0000000000002108. Online ahead of print.

ABSTRACT

BACKGROUND AND AIMS: Nocebo effects are thought to influence the rate of reported adverse events (AEs) and subject withdrawal in both the treatment and placebo groups of randomized clinical trials (RCTs). Neuromodulators are commonly prescribed to treat disorders of gut-brain interaction (DGBIs), but adherence to these medications is often limited by side effects such as headache, dry mouth, fatigue, and altered bowel habits. We performed a systematic review and meta-analysis to assess the proportion and risk difference of patients who experienced side effects leading to withdrawal in the placebo arm versus the treatment arm of RCTs of neuromodulators for DGBIs. We also sought to estimate the risk of developing any AE in the placebo arm of these studies as well as the rate of specific individual adverse events.

METHODS: We searched MEDLINE, Embase, Web of Science Core Collection, and the Cochrane Central Register of Controlled Trials Searches to identify RCTs that included terms for DGBIs and for commonly prescribed neuromodulators. We calculated pooled proportions of patients experiencing an AE leading to withdrawal in the active treatment group versus the placebo group with 95% confidence intervals (CI), the pooled proportions of patients experiencing any adverse event, the pooled proportions of patients experiencing specific adverse events such as dizziness and headache, the pooled proportions of patients experiencing severe adverse events and corresponding pooled risk differences with 95% CIs.

RESULTS: There were 30 RCTs included representing 2284 DGBI patients. 27 RCTs reported data on AEs leading to withdrawal. The pooled proportion of total patients with AEs leading to withdrawal in the placebo group was 4% (95% CI 0.02 – 0.04). The pooled proportion of patients with AEs leading to withdrawal who received neuromodulators was 9% (95% CI 0.06-0.13). In the 12 studies reporting data on patients experiencing at least one AE, the pooled proportion of patients experiencing any adverse event in the placebo group was 18% (95% CI 0.08 – 0.30), compared to 43% (95% CI 0.24 – 0.63) in the neuromodulator group. Thus, approximately 44% of the rate of withdrawal (0.04/0.09) and 42% of the rate reporting any side effects (0.18/0.43) in the neuromodulator group may be attributed to nocebo effects in the right context. Subgroup analysis by sex, medication class, risk of bias, and specific DGBIs revealed differing withdrawal rates. There was no statistically significant difference in patients experiencing individual AEs of dizziness, headache or diarrhea. Rates of dry mouth, fatigue and constipation were higher in treatment groups compared to placebo groups.

CONCLUSION: Patients with DGBIs in RCTs randomized to placebo groups frequently experience AEs and AEs that lead to withdrawal consistent with a strong nocebo effect. Non-specific AEs such as dizziness, headaches and diarrhea occurred similarly in patients receiving placebo compared to those receiving neuromodulators.

PMID:36563308 | DOI:10.14309/ajg.0000000000002108

Phys Rev Lett. 2022 Dec 9;129(24):241102. doi: 10.1103/PhysRevLett.129.241102.

ABSTRACT

A striking feature of the solar cycle is that at the beginning, sunspots appear around midlatitudes, and over time the latitudes of emergences migrate toward the equator. The maximum level of activity (e.g., sunspot number) varies from cycle to cycle. For strong cycles, the activity begins early and at higher latitudes with wider sunspot distributions than for weak cycles. The activity and the width of sunspot belts increase rapidly and begin to decline when the belts are still at high latitudes. Surprisingly, it has been reported that in the late stages of the cycle the level of activity (sunspot number) as well as the widths and centers of the butterfly wings all have the same statistical properties independent of how strong the cycle was during its rise and maximum phases. We have modeled these features using a Babcock-Leighton type dynamo model and show that the flux loss through magnetic buoyancy is an essential nonlinearity in the solar dynamo. Our Letter shows that the nonlinearity is effective if the flux emergence becomes efficient at the mean-field strength of the order of 10^{4} G in the lower part of the convection zone.

PMID:36563250 | DOI:10.1103/PhysRevLett.129.241102

Phys Rev Lett. 2022 Dec 2;129(23):230502. doi: 10.1103/PhysRevLett.129.230502.

ABSTRACT

Fracton models provide examples of novel gapped quantum phases of matter that host intrinsically immobile excitations and therefore lie beyond the conventional notion of topological order. Here, we calculate optimal error thresholds for quantum error correcting codes based on fracton models. By mapping the error-correction process for bit-flip and phase-flip noises into novel statistical models with Ising variables and random multibody couplings, we obtain models that exhibit an unconventional subsystem symmetry instead of a more usual global symmetry. We perform large-scale parallel tempering Monte Carlo simulations to obtain disorder-temperature phase diagrams, which are then used to predict optimal error thresholds for the corresponding fracton code. Remarkably, we found that the X-cube fracton code displays a minimum error threshold (7.5%) that is much higher than 3D topological codes such as the toric code (3.3%), or the color code (1.9%). This result, together with the predicted absence of glass order at the Nishimori line, shows great potential for fracton phases to be used as quantum memory platforms.

PMID:36563231 | DOI:10.1103/PhysRevLett.129.230502

Environ Sci Technol. 2022 Dec 23. doi: 10.1021/acs.est.2c03967. Online ahead of print.

ABSTRACT

Atmospheric models of secondary organic aerosol (OA) (SOA) typically rely on parameters derived from environmental chambers. Chambers are subject to experimental artifacts, including losses of (1) particles to the walls (PWL), (2) vapors to the particles on the wall (V2PWL), and (3) vapors to the wall directly (VWL). We present a method for deriving artifact-corrected SOA parameters and translating these to volatility basis set (VBS) parameters for use in chemical transport models (CTMs). Our process involves combining a box model that accounts for chamber artifacts (Statistical Oxidation Model with a TwO-Moment Aerosol Sectional model (SOM-TOMAS)) with a pseudo-atmospheric simulation to develop VBS parameters that are fit across a range of OA mass concentrations. We found that VWL led to the highest percentage change in chamber SOA mass yields (high NO_x: 36-680%; low NO_x: 55-250%), followed by PWL (high NO_x: 8-39%; low NO_x: 10-37%), while the effects of V2PWL are negligible. In contrast to earlier work that assumed that V2PWL was a meaningful loss pathway, we show that V2PWL is an unimportant SOA loss pathway and can be ignored when analyzing chamber data. Using our updated VBS parameters, we found that not accounting for VWL may lead surface-level OA to be underestimated by 24% (0.25 μg m^-3) as a global average or up to 130% (9.0 μg m^-3) in regions of high biogenic or anthropogenic activity. Finally, we found that accurately accounting for PWL and VWL improves model-measurement agreement for fine mode aerosol mass concentrations (PM_2.5) in the GEOS-Chem model.

PMID:36563184 | DOI:10.1021/acs.est.2c03967

Sci Adv. 2022 Dec 23;8(51):eade8817. doi: 10.1126/sciadv.ade8817. Epub 2022 Dec 23.

ABSTRACT

The pursuit of compact lasers with low thresholds has imposed strict requirements on tight light confinements with minimized radiation losses. Bound states in the continuum (BICs) have been recently demonstrated as an effective mechanism to trap light. However, most reported BIC lasers are still bulky due to the absence of in-plane light confinement. Here, we combine BICs and photonic bandgaps to realize three-dimensional light confinements, as referred to miniaturized BICs (mini-BICs). We demonstrate highly compact active mini-BIC resonators with a record high-quality (Q) factor of up to 32,500, which enables single-mode lasing with the lowest threshold of 80 W/cm² among the reported BIC lasers. In addition, photon statistics measurements further confirm the occurrence of the stimulated emission in our devices. Our work reveals a path toward compact BIC lasers with ultralow power consumption and potentially boosts the applications in cavity quantum electrodynamics, nonlinear optics, and integrated photonics.

PMID:36563161 | DOI:10.1126/sciadv.ade8817

Sports Med Arthrosc Rev. 2023 Mar 1;31(1):27-32. doi: 10.1097/JSA.0000000000000306. Epub 2022 Dec 27.

ABSTRACT

PURPOSE: One of the most frequent concerns of the increasing number of patients undergoing shoulder arthroplasty is the possibility to resume sport after surgery. This systematic review determined the rate of return to sport after total shoulder arthroplasty (TSA) and hemiarthroplasty (HA).

MATERIALS AND METHODS: The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed to perform this systematic review. A systematic electronic search was performed using the PubMed (MEDLINE), EMBASE, and Cochrane Library databases. All the studies analyzing the rates of reverse shoulder arthroplasties were pooled; data were extracted and statistically analyzed. Only studies with at least 10 adult patients recruited were considered. All studies had to relate return to sport after TSA or HA.

RESULTS: A total of 76 studies were included for a total of 694 patients. The mean age and average follow-up were, respectively, 64.5 years (range: 24 to 92 y) and 4.5 years (range: 0.5 to 12 y). The mean rate of return to sport ranged from 49.3% to 96.4%. The mean time to resume sports was 8.1 months. The overall rate of return to sport after the procedures, according to a random effect model, was 83%. The mean level of sports at the time of the survey was worsened in 9.4% (±2.82%), improved or reported from good to excellent in 55.6% (±13.6%), and did not change in 40% (±1.4) of patients.

CONCLUSIONS: On the basis of current available data, return to sports after TSA and HA is possible and is highly frequent. The subjective level of practice does not change or improve in most patients. More studies and better designed trials are needed to enrich the evidence on specific sport recovery after the procedure.

PMID:36563123 | DOI:10.1097/JSA.0000000000000306

Trans R Soc Trop Med Hyg. 2022 Dec 23:trac119. doi: 10.1093/trstmh/trac119. Online ahead of print.

ABSTRACT

BACKGROUND: Although the WHO has made an effort to ensure optimal participation of the community in mass drug administration (MDA) against lymphatic filariasis (LF) and soil-transmitted helminth infections (STHIs), studies are still reporting suboptimal coverage. This study assessed the knowledge and participation of the community in MDA against LF and SHTIs in Tanzania to provide updates on its acceptability.

METHODS: A cross-sectional study was conducted in Dar es Salaam from December 2021 to February 2022 among market vendors. The information regarding demographic characteristics, knowledge and participation in MDA was collected using a questionnaire. Statistical Package for Social science version 26 was used for data analysis.

RESULTS: More than half of the participants demonstrated an adequate level of knowledge of LF and STHI, 212 (50.8%) and 267 (64%), respectively. Only 286 (68.5%) reported having heard about MDA against LF and STHIs, out of which 119 (42%) had taken the medication. Of those who disagreed to participate in MDA, 20 (50%) claimed to fear the side effects of the medication.

CONCLUSIONS: This study found that the community has average knowledge and poor participation in MDA against LF and STHIs. Community sensitization is recommended to increase the participation of the community.

PMID:36563099 | DOI:10.1093/trstmh/trac119