A document by Zhiyi MA. Click on the document to view its contents.

An increasing number of COVID-19 cases worldwide has overwhelmed the healthcare system. Physicians are struggling to allocate resources and to focus their attention on high-risk patients, partly because early identification of high-risk individuals is difficult. This can be attributed to the fact that COVID-19 is a novel disease and its pathogenesis is still partially understood. However, machine learning algorithms have the capability to correlate a large number of parameters within a short period of time to identify the predictors of disease outcome. Implementing such an algorithm to predict high-risk individuals during the early stages of infection, would be helpful in decision making for clinicians. Here, we propose recommendations to integrate machine learning model with electronic health records so that a real-time risk score can be developed for COVID-19.

Background: Institutional factors have been shown to impact outcomes following orthotopic heart transplantation (OHT). This study evaluated center variability in the utilization of induction therapy for OHT and its implications on clinical outcomes. Methods: Adult OHT patients between 2010 and 2018 were identified from the UNOS registry. Transplant centers were stratified based on their rates of induction therapy utilization. Mixed-effects logistic regression models were created with drug-treated rejection within 1-year as primary endpoint and individual centers as random parameter. Risk-adjusted Cox regression was used to evaluate patient-level mortality outcomes. Results: In 17,524 OHTs performed at 100 centers, induction therapy was utilized in 48.6% (n=8411) with substantial variability between centers (IQR 21.4 – 79.1%).There were 36, 30, and 34 centers in the low (<29%), intermediate (29-66%), and high (>67%) induction utilization terciles groups, respectively. Induction therapy did not account for the observed variability in the treated rejection rate at 1-year among centers after adjusting for donor and recipient factors (p=0.20). No differences were observed in postoperative outcomes among induction utilization centers groups (all, p>0.05). Furthermore, there was a weak correlation between the percentage of induction therapy utilization at the center-level and recipients found to have moderate (r=0.03) or high (r=0.04) baseline risks for acute rejection at 1-year. Conclusions: This analysis demonstrates there is substantial variability in the use of induction therapy among OHT centers. In addition, there was a minimal correlation with baseline recipient risk or 1-year rejection rates, suggesting a need for better-standardized practices for induction therapy use in OHT.

The use of intraoperative epicardial ultrasound in order to aid physicians and surgeons in open cardiac surgery has been established for quite some time. Recently, the development of ultra-high frequency ultrasound (UFHUS) technology has resulted in high-resolution imaging capabilities previously unavailable for clinical use. This report is the first to describe the use of intraoperative UFHUS epicoronary scanning to assess coronary anatomy and visualize cardioplegia flow within native coronary vessels.

Extracorporeal membrane oxygenation (ECMO) is a technology that has allowed for further cardiopulmonary support in the setting of respiratory failure refractory to mechanical ventilation. While it has evolved since its first description, one area of improvement continues to be its implementation. With advancements in cannulation techniques, in recent years, there has been a plethora of new cannulas that has been introduced to the market. For urgent venous-venous cannulation, the right internal jugular vein along with either femoral veins remain the most utilized strategy due to minimal need for imaging support. This allows for safe bedside cannulation. However, as the number of days of ECMO support continue to increase bridging patients to an easier to ambulate and more comfortable cannulation strategy is preferred. Therefore, we describe a method for bridging right jugular-femoral cannulation to left subclavian placement of the CrescentTM Dual Lumen Catheter without interrupting ECMO support.

Diversification rates and evolutionary trajectories are known to be influenced by phenotypic traits and the geographic history of the landscapes that organisms inhabit. One of the most conspicuous traits in butterflies is their wing color pattern, which has been shown to be important in speciation. The evolution of many taxa in the Neotropics has also been influenced by the closure of the Panama Isthmus and the dynamic uplift of the Andes. Using a dated, species-level molecular phylogenetic hypothesis for Preponini, a colorful Neotropical butterfly tribe, we evaluated if diversification rates were constant or varied through time, and if they were dependent on color patterns or biogeographic events. We also estimated the rate of forewing color evolution and ancestral geographic ranges. We found that Preponini originated approximately 28 million years ago and that diversification has increased through time dependent on Andean uplift. Even though some clades show evolutionarily rapid transitions in coloration, these traits seem decoupled from diversification regimes. Preponini apparently originated within South America and range evolution has since been dynamic, congruent with Andean geologic activity, closure of the Panama Isthmus and Miocene climate variability. The potential involvement in mimicry rings with other butterfly groups might explain rapid changes in dorsal color patterns in this tribe.

The small brown planthopper (SBPH), Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) is a most destructive rice pest which has caused serious economic losses in China. To effectively manage this pest, we investigated genomic polymorphism, evaluated genetic divergence and populations genetic structure of SBPH at 31 sampling sites in China using a population genomics approach. In this study, we generated over 2,813,221,369 high-quality paired-end reads (413,689.55 Mb) across 306 individuals derived from double-digest restriction site-associated DNA sequencing (ddRAD-seq), and 1925 reliable single nucleotides (SNPs) were detected with an average sequencing depth of 13.99×. Overall, low levels of genetic diversity and strong genetic differentiation among all of populations were obtained (Global FST = 0.261). Neighbour-joining dendrograms, Bayesian clustering methods, discriminant analysis of principal components (DAPC) and principal component analysis (PCA) revealed three genetically distinct groups: Southwestern group, Northern group and Eastern group. Furthermore, we also observed a high degree of admixture, widespread hybridization and gene flow among populations of Northern China. A Mantel test indicated a pattern of isolation-by-distance throughout China (r = 0.211, P = 0.031). Neutrality test indicated SBPH has experienced a recent population expansion. Accordingly, our results provide new insights into the genetics of SBPH and thus contribute to develop effective management strategies for this pest.

1. Some small mammals exhibit Dehnel’s phenomenon, a drastic decline in body mass, braincase and brain size from summer to winter, followed by a regrowth in spring. This is accompanied by a reorganization of the brain and changes in other organs. The evolutionary link between these changes and seasonality remains unclear, although the magnitude of change varies between locations as the phenomenon is thought to lead to energy savings during winter. 2. Here we explored geographic variation of the intensity of Dehnel’s phenomenon in Sorex araneus. We compiled the literature on seasonal changes in braincase size, brain and body mass, supplemented by our own data from Poland, Germany and Czech Republic. 3. We analysed the effect of geographic and climate variables on the magnitude of change and patterns of brain reorganization. 4. From summer to winter the braincase height decreased by 13%, followed by 10% regrowth in spring. For body mass the changes were -21%/+82%, respectively. Changes increased along the north-east axis. Several climate variables were correlated with these transformations, confirming a link of the magnitude of the changes with environmental conditions. This relationship differed for the brain mass decline vs. regrowth, suggesting that they may have evolved under different selective pressures. 5. We found no geographic trends explaining variability in the brain mass changes although they were similar (-21%/+10%) to those of the braincase size. Underlying patterns of change in brain organisation in North-Eastern Poland were almost identical to the pattern observed in Southern Germany. This indicates that local habitat characteristics may play a more important role in determining brain structure than broad scale geographic conditions. 6. We discuss the techniques and criteria used for studying this phenomenon, as well as its potential presence in other taxa and the importance of distinguishing it from other kinds of seasonal variation.

The forest people around the world through their indigenous knowledge contribute to the sustainable management of forests. This article argues that the Sheka people in southwestern Ethiopia by their ecological knowledge, values, and spiritual use could manage the Ororo tree (Ekebergia capensis). The Ororo tree (Ekebergia capensis) is one of the most important endemic tree species in the Sheka zone southwestern Ethiopia and, at the same time, one of the most endangered species. Data collected on the indigenous ecological knowledge of the Sheka people and how the Ororo tree could be managed and conserved through the DEDO culture documented and the spiritual connection between the Ororo trees and the Sheka people traditional belief system measured. The findings revealed that through their traditional forestrelated knowledge, the Sheka people conserve and manage a single larger tree called Ororo. The Ororo tree is a special type of tree that has cultural and spiritual attachments that are presently non-existent. This unique forest conservation practice has been referred to as the DEDO culture. The culture of DEDO comes up with worshiping around the Ororo tree. Thus, the culture of DEDO played an important role in maintaining the conservation of the DEDO sacred tree (Ororo) and biodiversity therein. Over time, the DEDO sacred tree (Ororo) conservation culture has been decline, and various factors have contributed to the decline of this useful ecological knowledge.

1. Many policies and studies globally have highlighted the pivotal role of wetland ecosystems regarding wetland biota and their ecological status. With the strengthening of wetland ecosystem management legislation and policy, wetland restoration should also consider increasing habitat diversity to improve biota. We explore whether the construction of artificial ecological islands can increase the diversity of wetland birds and macroinvertebrates before assessing the effects of actively constructing islands via human intervention on wetland protection. 2. We discuss changes in waterfowl and macroinvertebrate diversity (i) with and without islands, (ii) at different water level gradients surrounding the islands, (ⅲ) on different island substrates, and (ⅳ) at different time scales. We used ANOVA, ANOSIM and cluster analysis to test the differences. 3. The waterfowl and macroinvertebrate communities had spatially heterogeneous distributions and vary over time due to both natural and anthropogenic stresses. The establishment of islands significantly changed the community composition and biodiversity of the macroinvertebrate and the waterfowl. The waterfowl and macroinvertebrate communities had different compositions at different water levels. Macroinvertebrates are the main food components of waterfowl and are closely related to them, and overall, abundance and diversity of macroinvertebrates directly and/or indirectly affect the biodiversity of waterfowl. Potentially, the construction of islands could provide some co-benefits for the conservation of wetland birds and macroinvertebrates. Synthesis and applications. Establishing artificial ecological islands in broad open water areas and increasing the water level gradient and substrate diversity. It can increase the micro-habitat diversity by artificially increasing the heterogeneity of the water depth conditions of a habitat. These changes can accommodate aquatic organisms with different ecological niches to increase the biodiversity, affecting the ecological restoration of inland freshwater marshes and wetlands. As such, wetland parks can play a positive role in protecting important bird migration pathways in northeast Asia.

In this study, we developed an integrated cellular automata and thermal lattice Boltzmann model to investigate the effects of different temperatures and velocities in a microbioreactor. Compared with previous studies this model accounted for the direct effects of transient temperature on biofilm growth and indirect effects caused by changes of properties. In addition, the algorithms on variations in solid boundary conditions, detachment and extra mass transport have been improved. Results showed that temperature affected both the maximum biofilm concentration and growth speed. Roughly a 10-75% increase in biofilm concentration was observed, while in some cases the time needed to reach maximum concentration decreased from 30 days to 5 days. Despite of geometrical symmetry, changes in the upper inlet characteristics were more effective on biofilm growth. This demonstrates the capability of the present model to simulate biofilm behaviour in the microbioreactor and its potential industrial and clinical applications.

In this study, time-space fractional heat conduction equation (HCEs), which plays an important role in thermal science, is considered on Cantor set. The analytical solution of this equation is obtained by using local fractional reduced differentiable transform method in fractal spaces. After giving preliminaries, some definitions and fundamental properties belong to this procedure are given. Then to make it easy to understand, this method is applied to homogeneous and non-homogeneous time-space fractional HCEs and analytic solutions are obtained. After that, physical behaviours of the solutions on fractal spaces are illustrated in 3D graphics. This shows the efficiency and reliability of the method.

We consider a parameter identification problem associated with a quasi-linear elliptic Neumann boundary value problem involving a parameter function a(⋅) and the solution u(⋅), where the problem is to identify a(⋅) on an interval $I:= g(\G)$ from the knowledge of the solution u(⋅) as g on $\G$, where $\G$ is a given curve on the boundary of the domain $\O\subseteq \R^3$ of the problem and g is a continuous function. The inverse problem is formulated as a problem of solving an operator equation involving a compact operator depending on the data, and for obtaining stable approximate solutions under noisy data, a new regularization method is considered. The derived error estimates are similar to, and in certain cases better than, the classical Tikhonov regularization considered in the literature in the recent past.

This paper is devoted to analyzing the controllability to rest of the Gurtin-Pipkin model, which is a class of differential equations with memory terms. The goal is not only to derive the state to vanish at some time but also to require the memory term to vanish at the same time, ensuring that the controlled system is controllable to rest. In order to get rid of the influence of memory, the controllability result is obtained by means of the Fourier type approach and the moment theory.

The substantial, tempered, and shifted fractional derivatives are introduced in a unified framework. Their properties are studied and, in the light of the strict sense criterion for derivative definitions, they are characterized and assessed. In the scope of the framework, new tempered linear sytems and transfer functions are introduced.

In this work, we demonstrate uniqueness of the weak solution to the fractional anisotropic Navier-Stokes system with only horizontal dissipation.

Using the invariance group properties of the system describing one-dimensional unsteady flow of a non-ideal dusty reacting gas, the evolutions of characteristic shock and singular surface are obtained. The influence of non-idealness, reaction mechanism and dusty gas parameters on the characteristic shock and singular surface are analyzed. Further, the amplitude of reflected wave and (or) transmitted wave, which generated from the interaction of a characteristic shock with a singular surface, and bounce in the acceleration of shock are shown.

Let $R$ be a commutative local ring whose maximal ideal is generated by a nilpotent element, and $\Mat (n, R)$ be the multiplicative monoid of the square matrices of order $n$ over $R$. In this article, we provide (1) the construction of the Green’s $H$-equivalence classes in $\Mat (n, R)$, and (2) the enumeration of the Green’s $H$-equivalence classes in $\Mat (n, Z/ p^d Z)$.

In this paper, some important results of the classical power series are generalized for the fractional power series. Some of these theorems are constructed by using conformable fractional derivatives. The ratio test has been specifically established to calculate the radius of convergence of a fractional power series, and several theorems of differentiability and integrability of the sum of a power series have been discussed in the sense of conformable fractional definition. In addition, the proposed series solution has been applied for the case of conformable fractional Airy differential equation.

The controlling nanofiller aggregation and strengthening interfacial interaction are of great scientific significance for mixed matrix membranes (MMMs). In this study, the polymer-embedded metal-organic framework (pMOF) microspheres (MSs) are designed by one-pot synthesis and employed as microfillers for improving separation performance of MMMs. Through adding polymer during solvothermal crystallization, the polymer chains are embedded into the MOF materials, and the morphologies of the MOFs are transformed from nanopaticles to polycrystalline MSs. Since the embedding of the identical polymer promotes the compatibility of polymeric matrixes and fillers, as well as the micrometer-sized porous MSs offer additionally superior and permanent transport pathways, the resulted MMMs display simultaneously enhanced selectivity and permeability for carbon capture. The CO2/CH4 selectivity and CO2 permeability of the pMOF MMMs are achieved at 1.3 and 2.2 times as those of the pure polymeric membranes, and 1.5 and 1.2 times as those of the MOF MMMs, respectively.

A bosonic Laplacian is a conformally invariant second order differential operator acting on smooth functions defined on domains in Euclidean space and taking values in higher order irreducible representations of the special orthogonal group. In this paper, we firstly introduce the motivation for study of the generalized Maxwell operators and bosonic Laplacians (also known as the higher spin Laplace operators). Then, with the help of connections between Rarita-Schwinger type operators and bosonic Laplacians, we solve Poisson’s equation for bosonic Laplacians. A representation formula for bounded solutions to Poisson’s equation in Euclidean space is also provided. In the end, we provide Green’s formulas for bosonic Laplacians in scalar-valued and Clifford-valued cases, respectively. These formulas reveal that bosonic Laplacians are self-adjoint with respect to a given L2 inner product on certain compact supported function spaces.

In this study, coupling of Rosenau-KdV and Rosenau-RLW equation is solved by a collocation technique based on quintic B-spline as basis functions which models the motion of shallow water waves. For this, spatial domain is discretized using quintic B-splines, which leads to a system of first order ordinary differential equations. Strong stability preserving Runge-Kutta method of fourth stage, third-order (SSP-RK43) is applied to solve the obtained system. All the calculations are performed without any linearization or transformation. Couple of test problems are solved to show the efficacy and accuracy of the technique by calculating L2 and L(infinity) error norms as well as discrete energy (E) and mass (Q) conservation properties. Stability analysis of the technique is performed using the concept of Jacobian matrix along with eigenvalues and is shown to be stable.

In this study a reproducing kernel Hilbert space method with Chebyshev function is proposed for approximating solutions of a nonlinear system of ordinary differential equations under multi-point boundary conditions. Based on reproducing kernel theory, reproducing kernel functions with a polynomial form will be erected in the reproducing kernel spaces spanned by the shifted Chebyshev polynomials. Convergence analysis of the proposed technique is theoretically investigated. This approach is successfully used for solving a system of ordinary differential equations with multi-point boundary conditions arising in flow of an electrically conducting nanofluid over an impermeable stretching cylinder.

The influence of the inputs on thermal risk parameters in a chemical reactor is important to know. This knowledge can establish adequate safety barriers. The following thermal risk parameters were studied: the maximum reaction temperature, the temperature rise and the time to reach this reaction maximum temperature. Global sensitivity analysis was proposed as a new perspective to evaluate the influence and the interaction of the inputs on thermal risk parameters. This method was applied to the exothermic system: epoxidation of cottonseed oil by performic acid in semibatch mode under isoperibolic conditions.