Independent Observers Research Articles

Electrocardiographic and Autonomic Nervous System Changes after Changes in the Posture of Children and Adolescents with Duchenne Muscular Dystrophy.

Duchenne Muscular Dystrophy (DMD) is a rare inherited neuromuscular disease. At first, cardiac involvement may be asymptomatic. Therefore, assessing patients using non-invasive methods can help detect any changes. Analyze the electrocardiogram (ECG) test and heart rate variability (HRV) of the DMD group and compare the information with that of the age-matched control group. A prospective study with 27 male patients with DMD (11.9 years old), who underwent clinical evaluation, ECG, echocardiogram, and Holter monitoring. ECG (200% increase) was assessed by two independent observers. HRV was measured over time (24 h) and in the frequency domain, in the supine and sitting positions. The healthy group consisted of nine patients (11.0 years old). A value of p < 0.05 was considered statistically significant. The mean ejection fraction (EF) was 60% (34 to 71%). The Kappa coefficient for ECG measurements ranged from 0.64 to 1.00. An increase in the R/S ratio in V1 was observed in 25.9% of the subjects, pathological Q wave in 29.6%, and fragmented QRS in 22.2% in inferior/high lateral regions, with a negative correlation with EF (p = 0.006). There was low HRV, without the influence of any variable, including treatment. With the change in position, there was an increase in HR (p = 0.004), but there was no change in HRV. The LF/HF ratio was 2.7 in the DMD group and 0.7 in the control group (p = 0.002). In DMD subjects, prominent R waves in V1 and changes in the inferior/high lateral regions occurred in almost 30% of the cases. Lower vagal tone was observed without the influence of the variables age, ejection fraction, QT dispersion, and treatment. Despite the increase in HR, there was no adequate HRV response to the change in position.

Selecting drill size for post space preparation based on final endodontic radiographs: An in vitro study.

For placement of intraradicular posts the intracanal filling material has to be removed. If drills are employed for this purpose, extra widening of the canal, incomplete cracks or root perforation are probable when inappropriate size of drill is used. This in vitro study assessed the efficacy of radiographs taken after completion of root canal therapy in selecting the appropriate-sized Peeso reamer for post space preparation. Canals of 53 extracted maxillary and mandibular teeth of different types were cleaned and shaped. Then with acrylic resin 3-dimensional model of the intracanal space of each tooth was fabricated. Next, all canals were filled with gutta-percha and teeth were radiographed buccolingually. Based on these radiographs two observers selected a Peeso reamer that best matched each canal's diameter. The diameter of the selected Peeso reamer was compared to the diameter of the corresponding resin model of each canal by two independent observers and the difference was measured. The data were analyzed by paired sample t-test using SPSS version 22. The diameter of the selected Peeso reamers ranged from 0.21 mm smaller to 0.12 mm larger than the diameter of intracanal spaces. The difference between reamer and resin model was less than 0.1 mm in 75% of the cases. The result of this study suggests that post-operation endodontic radiographs are reliable means for selecting a size of Peeso reamer that does not encroach on dentinal wall during removal of intracanal filling material and post space preparation.

Quantitative MRI assessment of joint effusion using T2-relaxometry at 3 Tesla: a feasibility and reproducibility study

ObjectiveT2-relaxometry could differentiate between physiological and haemorrhagic joint effusion (≥ 5% blood) in vitro. Are quantitative T2-relaxation time measurements of synovial fluid feasible and reproducible in vivo in clinically bleed-free joints of men with haemophilia?Materials and methodsIn this cross-sectional study, we measured T2-relaxation times of synovial fluid in clinically bleed-free ankles, knees or elbows of men with severe haemophilia A using a T2-mapping sequence (duration ≤ 7 min) at 3 Tesla MRI. Manual and circular regions of interest (ROI) were drawn in the synovial fluid of each joint by two independent observers to measure T2-relaxation times. Measurement feasibility was expressed as the success rate of the measurements by both observers. The interobserver and intraobserver reproducibility of the measurements were evaluated by the intraclass correlation coefficient of absolute agreement (ICC) and the limits of agreement (LoA) from Bland Altman analysis.ResultsWe evaluated 39 clinically bleed-free joints (11 ankles, 12 knees, 16 elbows) of 39 men (median age, 24 years; range 17–33) with severe haemophilia A. The success rate of the T2-measurements was ≥ 90%. Interobserver reliability was good to excellent (manual ROI: ICC = 0.92, 95% CI 0.76–0.97; circular ROI: ICC = 0.82, 95% CI 0.66–0.91) and interobserver agreement was adequate (manual ROI: LoA = 71 ms; circular ROI: LoA = 146 ms). Intraobserver reliability was good to excellent (manual ROI: ICC = 0.78, 95% CI − 0.06–0.94; circular RO: ICC = 0.99, 95% CI 0.98–0.99) and intraobserver agreement was good (manual ROI: LoA = 63 ms; circular ROI: LoA = 41 ms).ConclusionT2-relaxometry of synovial fluid in haemophilia patients is feasible with good interobserver and intraobserver reproducibility.

The Long-Term Esthetic and Radiographic Outcome of Implants Placed in the Anterior Maxilla after Ridge Preservation, Combining Bovine Xenograft with Collagen Matrix.

The objective of the study was to evaluate the long-term esthetic and radiographic results of implants placed in the anterior maxilla after ridge preservation, combining bovine xenograft with collagen matrix. Fifteen patients who required a single tooth extraction because of fracture, root resorption, or extended caries were included in the study. After extraction, all sites were grafted using Deproteinized Bovine Bone Mineral (DBBM) with collagen and covered by a resorbable collagen matrix (CM). Five months after socket grafting, implants were successfully installed. The implant diameter range was between 3.8 and 4.2 mm. All patients were monitored for over 7 years, both clinically and radiographically. Three independent observers evaluated the long-term esthetic outcome, employing the Pink Esthetic Score (PES) technique. Over a period exceeding seven years, a 100% survival rate was observed for all 15 implants, with minimal marginal bone loss. The mean PES was 11.40 (±1.44) at the first assessment and 11.38 (±1.63) at the second assessment. The difference was not statistically significant (p = 0.978), and the scores of PES measurements indicated excellent esthetic results even after seven years. Based on these preliminary results, it seems that placing collagen bovine bone in a fresh extraction socket, covered with a collagen matrix, can preserve the alveolar ridge and provide long-term stable esthetic results.

Frequently Encountered Artifacts in the Application of Dual-Energy Computed Tomography to Cardiovascular Imaging for Urate Crystals in Gout: A Matched-Control Study.

There is surging interest in using dual-energy computed tomography (DECT) to identify cardiovascular monosodium urate (MSU) deposits in patients with gout. We sought to examine the prevalence and characterization of cardiovascular DECT artifacts using non-electrocardiogram (EKG)-gated DECT pulmonary angiograms. We retrospectively reviewed non-EKG-gated DECT pulmonary angiograms performed on patients with and without gout at a single academic center. We noted the presence and locations of vascular green colorization using the default postprocessing two-material decomposition algorithm for MSU. The high- and low-energy grayscale images and advanced DECT measurements were used to determine whether they were true findings or artifacts. We classified artifacts into five categories: streak, contrast medium mixing, misregistration due to motion, foreign body, and noise. Our study included CT scans from 48 patients with gout and 48 age- and sex-matched controls. The majority of patients were male with a mean age of 67 years. Two independent observers attributed all areas of vascular green colorization to artifacts. The most common types of artifacts were streak (56% vs 57% between patients and controls, respectively) and contrast medium mixing (51% vs 65%, respectively). Whereas some of the default DECT measurements of cardiovascular green colorization were consistent with values reported for subcutaneous tophi, advanced DECT measurements were not consistent with that of tophi. Artifacts that could be misconstrued as cardiovascular MSU deposits were commonly identified in patients with and without gout on non-EKG-gated DECT pulmonary angiograms. These artifacts can inform future vascular DECT studies on patients with gout to minimize false-positive findings.

Vascular study of decellularized porcine long bones: Characterization of a tissue engineering model

IntroductionMassive bone allografts enable the reconstruction of critical bone defects in numerous conditions (e.g. tumoral, infection or trauma). Unfortunately, their biological integration remains insufficient and the reconstruction may suffer from several postoperative complications. Perfusion-decellularization emerges as a tissue engineering potential solution to enhance osseointegration. Therefore, an intrinsic vascular study of this novel tissue engineering tool becomes essential to understand its efficacy and applicability. Material and methods32 porcine long bones (humeri and femurs) were used to assess the quality of their vascular network prior and after undergoing a perfusion-decellularization protocol. 12 paired bones were used to assess the vascular matrix prior (N = 6) and after our protocol (N = 6) by immunohistochemistry. Collagen IV, Von Willebrand factor and CD31 were targeted then quantified. The medullary macroscopic vascular network was evaluated with 12 bones: 6 were decellularized and the other 6 were, as control, not treated. All 12 underwent a contrast-agent injection through the nutrient artery prior an angio CT-scan acquisition. The images were processed and the length of medullary vessels filled with contrast agent were measured on angiographic cT images obtained in control and decellularized bones by 4 independent observers to evaluate the vascular network preservation. The microscopic cortical vascular network was evaluated on 8 bones: 4 control and 4 decellularized. After injection of gelatinous fluorochrome mixture (calcein green), non-decalcified fluoroscopic microscopy was performed in order to assess the perfusion quality of cortical vascular lacunae. ResultsThe continuity of the microscopic vascular network was assessed with Collagen IV immunohistochemistry (p-value = 0.805) while the decellularization quality was observed through CD31 and Von Willebrand factor immunohistochemistry (p-values <0.001). The macroscopic vascular network was severely impaired after perfusion-decellularization; nutrient arteries were still patent but the amount of medullary vascular channels measured was significantly higher in the control group compared to the decellularized group (p-value <0.001). On average, the observers show good agreement on these results, except in the decellularized group where more inter-observer discrepancies were observed. The microscopic vascular network was observed with green fluoroscopic signal in almost every canals and lacunae of the bone cortices, in three different bone locations (proximal metaphysis, diaphysis and distal metaphysis). ConclusionDespite the aggressiveness of the decellularization protocol on medullary vessels, total porcine long bones decellularized by perfusion retain an acellular cortical microvascular network. By injection through the intact nutrient arteries, this latter vascular network can still be used as a total bone infusion access for bone tissue engineering in order to enhance massive bone allografts prior implantation.

A validation study to analyze the reliability of center of pressure data in static posturography in dogs.

Center of pressure (COP) parameters are frequently assessed to analyze movement disorders in humans and animals. Methodological discrepancies are a major concern when evaluating conflicting study results. This study aimed to assess the inter-observer reliability and test-retest reliability of body COP parameters including mediolateral and craniocaudal sway, total length, average speed and support surface in healthy dogs during quiet standing on a pressure plate. Additionally, it sought to determine the minimum number of trials and the shortest duration necessary for accurate COP assessment. Twelve clinically healthy dogs underwent three repeated trials, which were analyzed by three independent observers to evaluate inter-observer reliability. Test-retest reliability was assessed across the three trials per dog, each lasting 20 seconds (s). Selected 20 s measurements were analyzed in six different ways: 1 × 20 s, 1 × 15 s, 2 × 10 s, 4 × 5 s, 10 × 2 s, and 20 × 1 s. Results demonstrated excellent inter-observer reliability (ICC ≥ 0.93) for all COP parameters. However, only 5 s, 10 s, and 15 s measurements achieved the reliability threshold (ICC ≥ 0.60) for all evaluated parameters. The shortest repeatable durations were obtained from either two 5 s measurements or a single 10 s measurement. Most importantly, statistically significant differences were observed between the different measurement durations, which underlines the need to standardize measurement times in COP analysis. The results of this study aid scientists in implementing standardized methods, thereby easing comparisons across studies and enhancing the reliability and validity of research findings in veterinary medicine.

Soft Governance Across Digital Platforms Using Transparency

Platform governance helps align the activities of participating actors to deliver value within the platforms. These platforms can operate in environments where governance is intentionally or conventionally weak in favor of open access, frictionless transactions, or free speech. Such low- or no-governance environments leave room for illegitimate actors to penetrate platforms with illegitimate content or transactions. We propose that an external observer can employ transparency mechanisms to establish “soft” governance that allows participants in a low-governance environment to distinguish between sources of legitimate and illegitimate content. We examine how this might work in the context of disinformation Internet domains by training a machine learning classifier to discern between low-legitimacy from high-legitimacy content providers based on website registration data. The results suggest that an independent observer can employ such a classifier to provide an early, although imperfect, signal of whether a website is intended to host illegitimate content. We show that the independent observer can be effective at serving multiple platforms by providing intermediate prediction results that platforms can align with their unique governance priorities. We expand our analysis with a signaling game model to ascertain whether such a soft governance structure can be resilient to adversarial responses. Funding: Funding for this research was provided by UCL School of Management and Emory University. Supplemental Material: The online appendix is available at https://doi.org/10.1287/stsc.2023.0006 .

Characterization of renal masses with MRI-based radiomics: assessment of inter-package and inter-observer reproducibility in a prospective pilot study.

To evaluate radiomics features' reproducibility using inter-package/inter-observer measurement analysis in renal masses (RMs) based on MRI and to employ machine learning (ML) models for RM characterization. 32 Patients (23M/9F; age 61.8 ± 10.6years) with RMs (25 renal cell carcinomas (RCC)/7 benign masses; mean size, 3.43 ± 1.73cm) undergoing resection were prospectively recruited. All patients underwent 1.5T MRI with T2-weighted (T2-WI), diffusion-weighted (DWI)/apparent diffusion coefficient (ADC), and pre-/post-contrast-enhanced T1-weighted imaging (T1-WI). RMs were manually segmented using volume of interest (VOI) on T2-WI, DWI/ADC, and T1-WI pre-/post-contrast imaging (1-min, 3-min post-injection) by two independent observers using two radiomics software packages for inter-package and inter-observer assessments of shape/histogram/texture features common to both packages (104 features; n = 26 patients). Intra-class correlation coefficients (ICCs) were calculated to assess inter-observer and inter-package reproducibility of radiomics measurements [good (ICC ≥ 0.8)/moderate (ICC = 0.5-0.8)/poor (ICC < 0.5)]. ML models were employed using reproducible features (between observers and packages, ICC > 0.8) to distinguish RCC from benign RM. Inter-package comparisons demonstrated that radiomics features from T1-WI-post-contrast had the highest proportion of good/moderate ICCs (54.8-58.6% for T1-WI-1min), while most features extracted from T2-WI, T1-WI-pre-contrast, and ADC exhibited poor ICCs. Inter-observer comparisons found that radiomics measurements from T1-WI pre/post-contrast and T2-WI had the greatest proportion of features with good/moderate ICCs (95.3-99.1% T1-WI-post-contrast 1-min), while ADC measurements yielded mostly poor ICCs. ML models generated an AUC of 0.71 [95% confidence interval = 0.67-0.75] for diagnosis of RCC vs. benign RM. Radiomics features extracted from T1-WI-post-contrast demonstrated greater inter-package and inter-observer reproducibility compared to ADC, with fair accuracy for distinguishing RCC from benign RM. Knowledge of reproducibility of MRI radiomics features obtained on renal masses will aid in future study design and may enhance the diagnostic utility of radiomics models for renal mass characterization.

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Photon Counting Computed Tomography for Accurate Cribriform Plate (Lamina Cribrosa) Imaging in Adult Patients.

Detailed visualization of the cribriform plate is challenging due to its intricate structure. This study investigates how computed tomography (CT) with a novel photon counting (PC) detector enhance cribriform plate visualization compared to traditionally used energy-integrated detectors in patients. A total of 40 patients were included in a retrospective analysis, with half of them undergoing PC CT (Naeotom Alpha Siemens Healthineers, Forchheim, Germany) and the other half undergoing CT scans using an energy-integrated detector (Somatom Sensation 64, Siemens, Forchheim, Germany) in which the cribriform plate was visualized with a temporal bone protocol. Both groups of scans were evaluated for signal-to-noise ratio, radiation dose, the imaging quality of the whole scan overall, and, separately, the cribriform plate and the clarity of volume rendering reconstructions. Two independent observers conducted a qualitative analysis using a Likert scale. The results consistently demonstrated excellent imaging of the cribriform plate with the PC CT scanner, surpassing traditional technology. The visualization provided by PC CT allowed for precise anatomical assessment of the cribriform plate on multiplanar reconstructions and volume rendering imaging with reduced radiation dose (by approximately 50% per slice) and higher signal-to-noise ratio (by approximately 75%). In conclusion, photon-counting technology provides the possibility of better imaging of the cribriform plate in adult patients. This enhanced imaging could be utilized in skull base-associated pathologies, such as cerebrospinal fluid leaks, to visualize them more reliably for precise treatment.

Assessment of the Anterior Loop and Pattern of Entry of Mental Nerve Into the Mental Foramen: A Radiographic Study of Panoramic Images.

The precise location of the mental foramina is an essential landmark in planning the position of dental implants in the anterior mandible. Injury to inferior alveolar nerve during anterior mandibular implant surgery causes altered sensation which greatly affects patient satisfaction. In this study, we assessed the prevalence of anterior loop of mental nerve and the pattern of entry of mental nerve into the mental foramen. Three hundred panoramic radiographs (600 hemimandibles) obtained from records maintained in the Department of Oral Medicine and Radiology were randomly selected for the study. The radiographs were evaluated by two independent observers for the pattern of entry of mental nerve into the mental foramen on either side of the mandible and for the presence or absence of anterior loop of mental nerve. The most prevalent pattern of mental nerve observed was Straight pattern which totals to 67.5% followed by Anterior loop pattern (18.8%) and then the Perpendicular pattern (13.7%). There was no significant association between the gender and subtypes of looping pattern on the left and right side and a highly significant association between the side of the mandible and loop pattern was observed by Chi square test. The Anterior loop pattern of mental nerve has been found in 18.8% of the population suggesting to accurate planning with three-dimensional imaging techniques to avoid injury to mental nerve during dental implant placement and other surgical procedure involving the interforaminal region of the mandible.

Clinician and Consultation Factors Associated with CBT Fidelity Growth: Independent Observers vs. Consultant Fidelity Raters

ABSTRACT Post-training consultation support is linked to improvements in evidence-based treatment fidelity following initial training, but little is known about what makes it work, and how clinician-level factors may moderate its effects. This study examined the adherence and competence of N = 33 school-based clinicians trained to provide modular Cognitive Behavioral Therapy to youth, while receiving ongoing consultation. We examined two aspects of consultation as predictors of growth in adherence and competence, consultation dosage and use of session audio review. We also examined several clinician-level predictors of fidelity growth, including education, years of experience, burnout, and self-efficacy. Fidelity was rated by both independent observers and consultants, with differing findings. Independent observer ratings of adherence and competence did not change during consultation, and were not associated with any predictors. Consultant ratings of competence showed a trend toward growth during consultation. Greater clinician self-efficacy and years of experience were associated with lower initial consultant-rated competence, but more rapid growth over time. Higher consultation dosage and use of session audio review were negatively associated with growth in consultant-rated competence. These findings reinforce the need for further study of the active ingredients of consultation (i.e. consultation practices that help clinicians improve their treatment implementation), and the factors associated with perceptions of consultant fidelity raters.

Visualizing Agreement: Bland–Altman Plots as a Supplement to Inter-Rater Reliability Indices

ABSTRACT Even when raters demonstrate agreement in the use of a measure, limited score variability or violation of often-ignored statistical assumptions can result in lower reliability estimates than intuitively expected. This article uses data drawn from two randomized controlled trials of schema therapy and cognitive behavioral therapy for the treatment of major depression and binge eating disorder or bulimia nervosa (N = 212) to illustrate the limits of the intraclass coefficient. Randomly selected therapy sessions were rated for therapeutic alliance quality by independent observers using the well-validated Vanderbilt Psychotherapy Process Scale and Vanderbilt Therapeutic Alliance Scale. Scores on subscales related to therapist behavior were restricted, indicating consistent alliance-supportive actions. Inter-rater reliability estimates were low despite high agreement between raters, however. The use of Bland–Altman plots to visualize agreement and data spread is suggested as a useful tool for researchers, consistent with the ideal of exploring reliability from a number of perspectives.

Passive sea ice thickness inference using cryophones.

Mechanical properties of Arctic sea ice can be inferred by observations of in-ice propagation of compressional, shear, and flexural waves. During the 1980s, impulsive signals were generated by a lead ball or sledgehammer dropped onto the sea ice, and the inference required observation of wave speeds. During ICEX20 and ARCEX23, passive cryophone observations were made of naturally occurring compressional wave resonances. Average first-year ice thicknesses during ICEX20 and ARCEX23 were inferred to be 1.3 and 1.6 m, respectively; these are consistent with independent observations and indicate the potential for remote, autonomous monitoring of sea ice thickness.

Morphometric Analysis of the Neural Arch of C2 Vertebra in Indian Population.

The most common injuries to upper cervical spine are fractures of the second cervical vertebrae. The study aims to evaluate the morphometry of the neural arch of the second cervical vertebrae in the South Indian population. Sixty-three second cervical vertebrae of undetermined gender and age without any gross defect were used for the study. The dimensions of neural arch, including superior articular facet, inferior articular facet, pediculoisthmic component, lamina, spinous process, foramen transversarium, and vertebral foramen, were measured by two independent observers using digital vernier caliper accurate to 0.1 mm and the data was analyzed. Descriptive statistics were obtained for the variables. Paired t-test was done to compare the measurements between right and left sides. There was no statistical difference between the right and left sides of the dimensions of superior articular facets, foramen transversarium, and the transverse diameter of inferior articular facet. The anteroposterior diameter of the inferior articular facets was more on the right side (P = 0.009). The width of the pediculoisthmic component in both the superior and inferior aspects was found to be less on the right side than that of the left (P = 0.006 and P = 0.031, respectively). The thickness in the middle one-third of laminae was optimum for bilateral safe screw insertion (≥4.0 mm) in 77% specimens. In summary, measurements of the transverse diameter of superior articular facet and thickness of lamina differed significantly from those reported in literature. This should be kept in mind while doing neurosurgery procedures in the Indian population.

PET/CT and SPECT/CT imaging of 90Y hepatic radioembolization at therapeutic and diagnostic activity levels: Anthropomorphic phantom study.

Prior to 90Y radioembolization procedure, a pretherapy simulation using 99mTc-MAA is performed. Alternatively, a small dosage of 90Y microspheres could be used. We aimed to assess the accuracy of lung shunt fraction (LSF) estimation in both high activity 90Y posttreatment and pretreatment scans with isotope activity of ~100 MBq, using different imaging techniques. Additionally, we assessed the feasibility of visualising hot and cold hepatic tumours in PET/CT and Bremsstrahlung SPECT/CT images. Anthropomorphic phantom including liver (with two spherical tumours) and lung inserts was filled with 90Y chloride to simulate an LSF of 9.8%. The total initial activity in the liver was 1451 MBq, including 19.4 MBq in the hot sphere. Nine measurement sessions including PET/CT, SPECT/CT, and planar images were acquired at activities in the whole phantom ranging from 1618 MBq down to 43 MBq. The visibility of the tumours was appraised based on independent observers' scores. Quantitatively, contrast-to-noise ratio (CNR) was calculated for both spheres in all images. LSF estimation. For high activity in the phantom, PET reconstructions slightly underestimated the LSF; absolute difference was <1.5pp (percent point). For activity <100 MBq, the LSF was overestimated. Both SPECT and planar scintigraphy overestimated the LSF for all activities. Lesion visibility. For SPECT/CT, the cold tumour proved too small to be discernible (CNR <0.5) regardless of the 90Y activity in the liver, while hot sphere was visible for activity >200 MBq (CNR>4). For PET/CT, the cold tumour was only visible with the highest 90Y activity (CNR>4), whereas the hot one was seen for activity >100 MBq (CNR>5). PET/CT may accurately estimate the LSF in a 90Y posttreatment procedure. However, at low activities of about 100 MBq it seems to provide unreliable estimations. PET imaging provided better visualisation of both hot and cold tumours.

The potential recording of North Ionian Gyre’s reversals as a decadal signal in sea level during the instrumental period

In recent decades, the north Ionian Sea, central Mediterranean Sea, has witnessed shifts in surface current circulation from cyclonic to anticyclonic and vice versa at the quasi-decadal scale, a phenomenon termed the North Ionian Gyre (NIG) reversal. This process impacts parameters such as sea level by altering thermohaline properties and redistributing water masses at the sub-basin scale. Previous studies have shown that during anticyclonic (cyclonic) phases, the Ionian sea-level trend is falling (rising), the opposite of what is observed in other Mediterranean sub-basins. Assuming that sea level records reversals, this study employed signal decomposition to analyze satellite altimetry data and tide gauge observations across the region, some dating back to the 1900s. A distinct quasi-decadal periodicity emerges as the second dominant oscillatory mode from all independent observations, aligning its peaks and troughs (i.e., changes in sea-level trend) with known NIG reversals and associated changes in the state of North Ionian vorticity. Furthermore, this mode from altimetry data clearly depicts the spatial variability of sea level attributed to the opposite NIG states. This periodicity appears coherent among different sub-basins within the domain, especially in the eastern Mediterranean, with a shared generalized out of phase and weakening occurred from the 1930s to the 1950s. This study presents a century-scale reconstruction of NIG reversals, contributing to the understanding of this phenomenon prior to 1987 using direct observations from sea-level data.

Investigating twelve mainstream global precipitation datasets: Which one performs better on the Tibetan Plateau?

Acquiring precipitation information is a critical yet challenging task for the Tibetan Plateau (TP) with sparse gauges and high altitudes. Presently, there is a multitude of operational precipitation products merged from different data sources. A major concern within the TP science community is which one of these available precipitation datasets performs best on the TP. To address this concern, we selected and compared twelve widely used global precipitation datasets, including six satellite-based precipitation estimates (GSMaP-Gauge, IMERG-Final, TMPA-v7, CMORPH-BLD, PERSIANN-CDR, CHIRPS), five reanalysis data (ERA5, JRA-55, MERRA2, GLDAS, NCEP2), and one multi-source fusion product (MSWEP). Benchmarked against both automatic weather stations and independent field observations, we comprehensively investigate the spatiotemporal accuracy and regional applicability of these global precipitation products on the TP. The evaluation results indicate that almost all the datasets have a consistent tendency to overestimate lower precipitation rates and underestimate higher ones. However, four out of the twelve studied datasets (i.e., GSMaP-Gauge, IMERG-Final, ERA5, and MSWEP) significantly outperform others. Specifically, the two GPM-based satellite precipitation products, GSMaP-Gauge and IMERG-Final, can better reflect the difference between different rain intensities and perform better at moderate rain rates. In contrast, the reanalysis-based ERA5 exhibits a more clustered data series, with relatively higher accuracy at low precipitation rates. Moreover, ERA5 demonstrates a stable superiority in the mountainous areas characterized by complex local terrains. Furthermore, we find that the applicability of different precipitation datasets has an obvious region-related feature. Thus, a regional distribution map was made to clearly outline the optimal choice of current mainstream global precipitation datasets over different climate zones within the TP. This study can offer valuable insights for TP researchers, especially aiding them to select the appropriate precipitation data for their specific studies.

Travel to allies or adversaries? A compositional analysis of U.S. diplomatic visits

AbstractObjectiveWhen and why do U.S. leaders visit their allies or adversaries? Much of the literature on diplomatic visits treats each visit as an independent observation. In this article, we analyze high‐level diplomatic visits as compositional data based on the assumption that they are scarce political resources.MethodsWe conduct a compositional analysis of U.S. high‐level officials' diplomatic visits between 1950 and 2010.ResultsWe find that U.S. diplomatic visits to its allies are defense‐oriented, so leaders spend more time touring them during their security crises to signal reassurance. Additionally, we find that visits to adversaries are motivated by leaders' domestic political concerns, particularly their high public unpopularity. Visiting a hostile country is a challenging and salient foreign policy task, providing a high‐profile opportunity to improve their domestic image and standing. This effect is particularly significant in a divided government, where leaders turn to foreign policy to maximize domestic political impacts amid domestic gridlock.ConclusionThe findings suggest that U.S. leaders travel to allies and adversaries for distinct strategic purposes. Furthermore, our study suggests that future research on diplomatic visits should use a compositional variable approach to better model the dynamics and competitive nature of travel diplomacy.