A Modified Multiplicative Thinning-Based INARCH Model: Properties, Saddlepoint Maximum Likelihood Estimation, and Application.

In this article, we propose a modified multiplicative thinning-based integer-valued autoregressive conditional heteroscedasticity model and use the saddlepoint maximum likelihood estimation (SPMLE) method to estimate parameters. A simulation study is given to show a better performance of the SPMLE. The application of the real data, which is concerned with the number of tick changes by the minute of the euro to the British pound exchange rate, shows the superiority of our modified model and the SPMLE.

A Systematic Review of INGARCH Models for Integer-Valued Time Series.

Count time series are widely available in fields such as epidemiology, finance, meteorology, and sports, and thus there is a growing demand for both methodological and application-oriented research on such data. This paper reviews recent developments in integer-valued generalized autoregressive conditional heteroscedasticity (INGARCH) models over the past five years, focusing on data types including unbounded non-negative counts, bounded non-negative counts, Z-valued time series and multivariate counts. For each type of data, our review follows the three main lines of model innovation, methodological development, and expansion of application areas. We attempt to summarize the recent methodological developments of INGARCH models for each data type for the integration of the whole INGARCH modeling field and suggest some potential research topics.

Retrospective Study of 23 Patients with Traumatic Posterolateral Tibial Plateau Fracture Treated in a Single Center Between 2017 and 2019 with Lateral Arthrotomy, Reduction, and Plate Fixation Using the Frosch Approach.

BACKGROUND The Frosch approach is a posterolateral surgical procedure performed with or without osteotomy of the fibula for the treatment of posterolateral tibial plateau fractures (PLFs). This retrospective study from a single center aimed to evaluate 23 patients with PLFs who underwent surgical reduction with the Frosch approach between January 2017 and October 2019. MATERIAL AND METHODS Twenty-three patients, 4 with Schatzker type V and 19 with Schatzker type II fractures were enrolled. Postoperative radiographs were performed regularly to measure the medial proximal tibial angle (MTPA), lateral posterior slope angle (LPSA), medial posterior slope angle (MPSA), and articular step-off to evaluate the fracture reduction. At the last follow-up, the Hospital for Special Surgery (HSS) knee score and knee range of motion (ROM) were used to assess knee function. RESULTS Radiograph examinations indicated excellent reduction and fixation of fractures in all patients. The average HSS scores and ROM of the 23 patients were 88.0±3.5 and 131.8±7.8°, respectively, with an average of 30.5±4.6 months of follow-up. Skin numbness occurred in 3 patients but was recovered within 6 months. One patient sustained superficial wound infection, and another patient had superficial adipose tissue liquefaction necrosis. CONCLUSIONS This experience from a single center demonstrated the advantage of the Frosch approach in visualizing the posterolateral and lateral tibial plateau from a single surgical incision and resulted in excellent postoperative outcomes at follow-up when evaluated by the HSS score, ROM, and radiographic evaluation of the MTPA, LPSA, and MPSA.

A New First-Order Integer-Valued Autoregressive Model with Bell Innovations.

A Poisson distribution is commonly used as the innovation distribution for integer-valued autoregressive models, but its mean is equal to its variance, which limits flexibility, so a flexible, one-parameter, infinitely divisible Bell distribution may be a good alternative. In addition, for a parameter with a small value, the Bell distribution approaches the Poisson distribution. In this paper, we introduce a new first-order, non-negative, integer-valued autoregressive model with Bell innovations based on the binomial thinning operator. Compared with other models, the new model is not only simple but also particularly suitable for time series of counts exhibiting overdispersion. Some properties of the model are established here, such as the mean, variance, joint distribution functions, and multi-step-ahead conditional measures. Conditional least squares, Yule-Walker, and conditional maximum likelihood are used for estimating the parameters. Some simulation results are presented to access these estimates' performances. Real data examples are provided.

A New Extension of Thinning-Based Integer-Valued Autoregressive Models for Count Data.

The thinning operators play an important role in the analysis of integer-valued autoregressive models, and the most widely used is the binomial thinning. Inspired by the theory about extended Pascal triangles, a new thinning operator named extended binomial is introduced, which is a general case of the binomial thinning. Compared to the binomial thinning operator, the extended binomial thinning operator has two parameters and is more flexible in modeling. Based on the proposed operator, a new integer-valued autoregressive model is introduced, which can accurately and flexibly capture the dispersed features of counting time series. Two-step conditional least squares (CLS) estimation is investigated for the innovation-free case and the conditional maximum likelihood estimation is also discussed. We have also obtained the asymptotic property of the two-step CLS estimator. Finally, three overdispersed or underdispersed real data sets are considered to illustrate a superior performance of the proposed model.

Diagnostic checks in time series models based on a new correlation coefficient of residuals.

For checking time series models, the Ljung-Box, Li-Mak and Zhu-Wang statistics play an important role, which use the Pearson's correlation coefficient to implement (squared) residual (partial) autocorrelation tests. In this paper, we replace the Pearson's correlation coefficient with a new rank correlation coefficient and propose a new test statistic to conduct diagnostic checks for residuals in autoregressive moving average models, autoregressive conditional heteroscedasticity models and integer-valued time series models, respectively. We conduct simulations to assess the performance of the new test statistic, and compare it with existing ones, and the results show the superiority of the proposed one. We use three real examples to exhibit its usefulness.

Biomechanical comparison of femoral neck anti-rotation and support system versus femoral neck system for unstable pauwels III femoral neck fractures.

BACKGROUND: The optimal treatment method for managing unstable Pauwels III femoral neck fractures remains undetermined. The aim of this study was to compare the biomechanical properties of two types of Femoral Neck Anti-rotation and Support System (FNAS) and a Femoral Neck System (FNS) in unstable Pauwels III femoral neck fractures. METHODS: Eighteen synthetic femoral models were implanted with one of three fixation devices: FNS, FNAS I, or FNAS II. An unstable Pauwels III (OTA/AO 31-B2.3) femoral neck fracture was simulated using a custom-made needle and osteotomy guide. Torsion and axial compression loading tests were conducted, and the torque, torsion angle, load to failure, displacement, and stiffness values were recorded. RESULTS: FNAS II exhibited significantly higher torsional stiffness (0.67 ± 0.10 Nm/°) compared to FNAS I (0.52 ± 0.07 Nm/°, P = 0.01) and FNS (0.54 ± 0.07 Nm/°, P = 0.005). FNS demonstrated significantly greater mean axial stiffness (239.24 ± 11.38 N/mm) than both FNAS I (179.33 ± 31.11 N/mm, P = 0.005) and FNAS II (190.07 ± 34.11 N/mm, P = 0.022). FNAS I (302.37 ± 33.88 N/mm, P = 0.001) and FNAS II (319.59 ± 50.10 N/mm, P < 0.001) showed significantly higher initial axial stiffness compared to FNS (197.08 ± 33.68 N/mm). Both FNAS I and II improved resistance to deforming forces at a load level before approximately 1000 N, which is sufficient to withstand the load from most daily life activities. No significant differences were observed in compression failure load among the groups. The failure patterns at the point of failure included the pull-out of the distal locking screw and reverse oblique intertrochanteric femur fracture for FNS, while for FNAS I and II, the failures were characterized by a cleft on the calcar femorale and a decrease in the load-displacement curve. CONCLUSIONS: In unstable Pauwels III femoral neck fractures, the FNAS II enhances stability and is easier to manage for reoperation. The results of the current study support the potential of FNAS II as an alternative option for treating unstable Pauwels III femoral neck fractures in young individuals.

The Exosome-Mediated Bone Regeneration: An Advanced Horizon Toward the Isolation, Engineering, Carrying Modalities, and Mechanisms.

Exosomes, nanoparticles secreted by various cells, composed of a bilayer lipid membrane, and containing bioactive substances such as proteins, nucleic acids, metabolites, etc., have been intensively investigated in tissue engineering owing to their high biocompatibility and versatile biofunction. However, there is still a lack of a high-quality review on bone defect regeneration potentiated by exosomes. In this review, the biogenesis and isolation methods of exosomes are first introduced. More importantly, the engineered exosomes of the current state of knowledge are discussed intensively in this review. Afterward, the biomaterial carriers of exosomes and the mechanisms of bone repair elucidated by compelling evidence are presented. Thus, future perspectives and concerns are revealed to help devise advanced modalities based on exosomes to overcome the challenges of bone regeneration. It is totally believed this review will attract special attention from clinicians and provide promising ideas for their future works.

Leukemia risk assessment of exposure to low-levels of benzene based on the linearized multistage model.

Objectives: To assess leukemia risk in occupational populations exposed to low levels of benzene. Methods: Leukemia incidence data from the Chinese Benzene Cohort Study were fitted using the Linearized multistage (LMS) model. Individual benzene exposure levels, urinary S-phenylmercapturic acid (S-PMA) and trans, trans-muconic acid (t, t-MA) were measured among 98 benzene-exposed workers from factories in China. Subjects were categorized into four groups by rounding the quartiles of cumulative benzene concentrations (< 3, 3-5, 5-12, ≥12 mg/m3·year, respectively). The risk of benzene-induced leukemia was assessed using the LMS model, and the results were validated using the EPA model and the Singapore semi-quantitative risk assessment model. Results: The leukemia risks showed a positive correlation with increasing cumulative concentration in the four exposure groups (excess leukemia risks were 4.34, 4.37, 4.44 and 5.52 × 10-4, respectively; Ptrend < 0.0001) indicated by the LMS model. We also found that the estimated leukemia risk using urinary t, t-MA in the LMS model was more similar to those estimated by airborne benzene compared to S-PMA. The leukemia risk estimated by the LMS model was consistent with both the Singapore semi-quantitative risk assessment model at all concentrations and the EPA model at high concentrations (5-12, ≥12 mg/m3·year), while exceeding the EPA model at low concentrations (< 3 and 3-5 mg/m3·year). However, in all four benzene-exposed groups, the leukemia risks estimated by these three models exceeded the lowest acceptable limit for carcinogenic risk set by the EPA at 1 × 10-6. Conclusion: This study demonstrates the utility of the LMS model derived from the Chinese benzene cohort in assessing leukemia risk associated with low-level benzene exposure, and suggests that leukemia risk may occur at cumulative concentrations below 3 mg/m3·year.

Modeling air quality level with a flexible categorical autoregression.

To study urban air quality, this paper proposes a novel categorical time series model, which is based on a linear combination of bounded Poisson distribution and discrete distribution to describe the dynamic and systemic features of air quality, respectively. Daily air quality level data of three major cities in China, including Beijing, Shanghai and Guangzhou, are analyzed. It is concluded that the air quality in Beijing is the worst among the three cities but is gradually improving, and its dynamics is also the most pronounced. Theoretically, the design of our model increases the flexibility of the probabilistic structure while ensuring a dynamic feedback mechanism without high computational stress. We estimate the parameters through an adaptive Bayesian Markov chain Monte Carlo sampling scheme and show the satisfactory finite sample performance of the model through simulation studies.

A preliminary study of the surgical approach for posterior tibial plateau fractures: Based on posterior fragment segment classification.

PURPOSE: The optimal surgical approach for the posterior tibial plateau fractures (PTPFs) remains controversial. This study aims to establish a method for posterior fragment segment classification to guide the choice of surgical approach and to reveal the outcome of their early reduction and health status. METHODS: The medical records of 42 PTPFs patients treated with the strategy were collected retrospectively from December 2017 to December 2021. The posterior cortex of the tibial plateau was classified into postero-medial (PM), postero-central (PC), and postero-lateral (PL) segments. A posteromedial inverted L-shaped approach was adopted when the fractures involved the PM segment in the presence or absence of PC. The Frosch approach was performed when the PL segment was concerned. Fractures containing both PM and PL segments were treated by combined approaches. Four factors were measured to evaluate the reduction effect, including medial proximal tibial angle (MPTA), lateral posterior slope angle (LPSA), medial posterior slope angle (MPSA), and articular step-off. The Short Form 36 (SF-36) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were completed at the last follow-up to assess health status and the degree of osteoarthritis. RESULTS: A posteromedial inverted L-shaped approach was adopted in 16 PTPFs patients, a Frosch approach was adopted in 14 PTPFs patients, and a combined approach was adopted in 12 PTPFs patients. Immediate radiographic results indicated a promising fixation performance with this treatment strategy. The results of SF-36 and WOMAC scores reported good health status in all patients with a mean follow-up time of 34.50 (23-50) months. Two patients developed superficial wound infections, and one patient had liquefaction necrosis in adipose tissue. Although skin numbness occurred in 4 patients, they recovered within 6 months. CONCLUSION: PTPFs patients treated under the guidance of posterior fragment segment classification achieved encouraging levels of immediate fixation and health status.

The Biosafety Evaluation for Crustaceans: A Novel Molluscicide PBQ Using against Oncomelania hupensis, the Intermediate Host of Schistosoma japonica.

A new formulation (suspension concentrate, SC) of PBQ [1-(4-chlorophenyl)-3-(pyridin-3-yl) urea] was used in water network schistosomiasis-endemic areas to test its molluscicidal efficacy and the acute toxicity to crustaceans. PBQ (20% SC), 26% metaldehyde, and niclosamide suspension concentrate [MNSC (26% SC)] were used both in ditch and field experiments for the molluscicidal efficacy comparison. Acute toxicity tests of two molluscicides were conducted using Neocaridina denticulate and Eriocheir sinensis. Both in the field and ditch experiments, PBQ exhibited comparable molluscicidal efficacy with MNSC. At doses of 0.50 g/m3 and 0.50 g/m2, the snail mortalities were more than 90% three days after PBQ (20% SC) application. Compared with previous tests, PBQ (20% SC) exhibited higher molluscicidal activity than PBQ (25% wettable powder, 25% WP) used in Jiangling and showed similar mollucicidal activity to PBQ (25% WP) used in Dali and Poyang Lake. The 96 h LC50 value of MNSC against Eriocheir sinensis was 283.84 mg a.i./L. At the concentration of PBQ (20% SC) 1000 mg a.i./L, all Eriocheir sinensis were alive. The 96 h LC50 values of PBQ and MNSC against Neocaridina denticulate were 17.67 and 14.05 mg a.i./L, respectively. In conclusion, PBQ (20% SC) had a comparable molluscicidal efficacy with MNSC (26% SC) and PBQ (25% WP). Furthermore, it showed lower toxicity to the crustacean species, better solubility, no floating dust, and convenience for carriage. PBQ (20% SC) was suitable for controlling snails in the water network schistosomiasis-endemic areas.