Stationary Status Research Articles

Construction and validation of a risk prediction model for soldiers with frostbite in northeast China: a cross-sectional study

BackgroundOne of the challenges of physical training in extreme condition is frostbite, especially in Northeast China. In this study, we aimed to construct a risk prediction model for frostbite among soldiers in Northeast China, and verify its effect.Methods698 participants were selected via convenience sampling from Northeast China from December 2021 to January 2022 (winter). They were randomly divided into a training set (N = 479) and a testing set (N = 202) in a ratio of 7:3. All participants completed a researcher-made questionnaire on frostbite. The prediction model was constructed through the use of Logistic regression analysis, which was used to predict the independent risk factors for frostbite formation and screen significant indicators. The model’s performance was assessed using the receiver operating characteristic (ROC) curve and decision curve analysis (DCA) to evaluate the prediction efficiency and goodness of fit.ResultsThe incidence of frostbite in the training set was 19.83% (95 people), all of which were first-degree frostbite. Among them, frostbite in multiple parts was the most common (58.95%), followed by singular body parts like hands (24.21%), ears (11.58%) and feet (5.26%). Single factor logistic regression analyses showed that ambient temperature, ambient wind speed, outdoor stationary time, stationary status, and history of frostbite are independent risk factors that affect the occurrence of frostbite. Furthermore, we constructed the frostbite risk prediction model for soldiers in the northeastern region of China. The area under the receiver operating characteristic curve (AUC) for the risk of frostbite in the training set and testing set was 0.816 (95% CI, 0.770 ~ 0.862) and 0.787 (95% CI, 0.713 ~ 0.860), respectively. The Hosmer-Lemeshow test of the model showed χ2 = 11.328 and P = 0.184 (> 0.05). The DCA curve indicated that most of the clinical net benefits of the model are greater than 0, demonstrating good clinical usefulness.ConclusionThe constructed frostbite prediction model can effectively identify soldiers with a higher risk of frostbite. It provided theoretical support for commanders to take preventive measures to reduce the incidence of frostbite among soldiers and was of great clinical guiding significance.

Stationary status of discrete and continuous age-structured population models

From Leonhard Euler to Alfred Lotka and in recent years understanding the stationary process of the human population has been of central interest to scientists. Population reproductive measure NRR (net reproductive rate) has been widely associated with measuring the status of population stationarity and it is also included as one of the measures in the millennium development goals. This article argues how the partition theorem-based approach provides more up-to-date and timely measures to find the status of the population stationarity of a country better than the NRR-based approach. We question the timeliness of the value of NRR in deciding the stationary process of the country. We prove associated theorems on discrete and continuous age distributions and derive measurable functional properties. The partitioning metric captures the underlying age structure dynamic of populations at or near stationarity. As the population growth rates for an ever-increasing number of countries trend towards replacement levels and below, new demographic concepts and metrics are needed to better characterize this emerging global demography.

On the recovery of internal source for an elliptic system by neural network approximation

Abstract Consider a source detection problem for a diffusion system at its stationary status, which is stated as the inverse source problem for an elliptic equation from the measurement of the solution specified only in part of the domain. For this linear ill-posed problem, we propose to reconstruct the interior source applying neural network algorithm, which projects the problem into a finite-dimensional space by approximating both the unknown source and the corresponding solution in terms of two neural networks. By minimizing a novel loss function consisting of PDE-fit and data-fit terms but without the boundary condition fit, the modified deep Galerkin method (MDGM) is applied to solve this problem numerically. Based on the stability result for the analytic extension of the solution, we strictly estimate the generalization error caused by the MDGM algorithm employing the property of conditional stability and the regularity of the solution. Numerical experiments show that we can obtain satisfactory reconstructions even in higher-dimensional cases, and validate the effectiveness of the proposed algorithm for different model configurations. Moreover, our algorithm is stable with respect to noisy inversion input data for the noise in various structures.

Longitudinal assessment of milestone development among internal medicine residents in Taiwan

The Accreditation Council for Graduate Medical Education (ACGME) milestones have been implemented in residency training worldwide. We investigated the development of individual competency in first-year residents (R1) and second-year postgraduate students (PGY2) who received internal medicine training in Taiwan. A multicenter observational cohort study was conducted to evaluate the competency-based milestone evaluation designed by the Taiwan Society of Internal Medicine in 2019. The evaluation was based on the ACGME-accredited milestone ratings. Periodic evaluation of milestone achievements of R1 and PGY2, who entered the internal medicine residency training at six medical centers, was performed. Each resident was evaluated every 3 months. Among the 98 R1 enrolled in 2019, substantial improvement in sub-competencies, including skill in performing procedures (Patient Care 4), clinical knowledge (Medical Knowledge 1), knowledge of diagnostic testing and procedures (Medical Knowledge 2), and identify impact the cost of health care and practices cost-effective care (Systems Based Practice 3) during the two years of training. Among the 107 R1 and 46 PGY2 enrolled in 2020, no significant difference in baseline milestone ratings was observed. However, the milestone assessments of R1 in 2020 showed improvement in nearly all sub-competencies compared with the stationary status of PGY2 in 2020. We demonstrate the application of ACGME-based accredited milestone ratings to target the educational goals of internal medicine residency training in Taiwan. Differences in milestone ratings between different PGY training systems exist. The long-term impact of performance among different PGY training systems requires further investigation.

Energy Consumption Dynamics and Sustainable Growth in Nigeria

The paper empirically examined the energy consumption dynamics and sustainable growth in Nigeria using time series data spanning from 1980 to 2020. The major sources of data were from the World Development Index (WDI) and Central Bank of Nigeria (CBN) Statistical Bulletin various issues. In checking the stationary status of all the data engaged, the paper applied modified Ng-Perron unit root test to check the stationary properties of the series, and the results showed that GDP growth rate (GDPgr) was integrated at level (that is I(0)) while electricity consumption (ECNP), coal consumption (CCNP) and petroleum consumption (PCNP) were integrated of order one (that is, I (1)). This justified the application of Autoregressive Distributed Lag (ARDL) model of co-integration, whose results revealed that all series exhibited a stable long run relationship among them. The ARDL bound test result showed that the F-statistics was 4.35, which was greater than the upper bounds critical value of 3.79 at 5 percent level of significant. This further showed that the null hypothesis, which postulated that energy consumption dynamics has no significant impact on sustainable growth in Nigeria can be rejected. Based on the above findings, the paper submitted inter-alia that government should establish a renewable biomass as a supplement to energy sources in order to drive a sustainable growth in Nigeria.

Arc-remodified long period fiber grating for monitoring absolute bending condition

In this paper, we propose an arc-remodified long period fiber grating (AR-LPFG) and introduce the ratios of shift-distance of two resonant dips (RSRDs) as a novel distinguishing index to monitor bending absolute condition which refers to detect the curvature and directions of fiber under a stationary status. The AR-LPFG is configured by arc-remodifying the LPFG that prepared from CO2 laser. The refractive index of the fiber is modulated again by the arc-remodification method which results in new resonant dips. Two orthogonal bending directions are distinguished by comparing the RSRDs, which are calculated to be 0.51 and 1.42 for 0° and 90°, respectively. Two opposite bending directions are distinguished by the opposite shift directions of two resonant dips. The stability and reliability of the novel distinguishing method are verified by a series of comparative experiments. The AR-LPFG still contains a conspicuous performance for bending variation sensing with a maximum sensitivity of 17.02 nm m−1. The AR-LPFG, together with the orientation distinguishing index, can be widely applied at the fields that the bending relative variation or absolute condition need to be monitored.

Impact of External Debt on Economic Growth Rate: An Empirical Evidence from Pakistan

The major objective of this study is to check the effect of external debt on the GDP growth of Pakistan. For this purpose annual time series data were used for the period 1980 to 2020. Augmented Dickey-Fuller test was applied to check the stationary status of the data and the least square method was applied for the estimation of the results. For the analysis GDP growth rate was taken as a dependent variable and other variables, such as economic growth (Annual %), inflation rate (CPI %), Foreign Direct Investment net inflow (% of GDP), multi-lateral debt services (% of public and publically generated debt service), Total debt service (% of GNI), Short term debt (% of total reserves) were taken as explanatory variables. Findings revealed that the total debt and multilateral debt negatively affect the GDP growth rate, whereas, FDI and short term debt are positively associated with growth rate. It is suggested that to improve the economic growth Pakistan should focus on investment projects and there is a need to implementation better policies for foreign debt utilization

Impact of External Debt on Economic Growth in Nigeria

This study examined external borrowing and economic growth in Nigeria covering the period 1981 – 2019. The main objective of the study is to ascertain the impact of external borrowing on economic growth in Nigeria. Times series data on GDP, external debt, exchange rate, external debt servicing payments and inflation were extracted from the Central Bank of Nigeria (CBN) statistical bulletin 2018 was used for the study. The method of data analysis and evaluation were the unit-root test which was used to ascertain the stationary status of the variables, the linear regression with the application of Ordinary Least Squares (OLS) technique and the Granger causality analysis. The major findings of the study are that all the variables are stationary at first difference I(1), external debt has a negative and insignificant relationship with economic growth in Nigeria ( = -0004912, p-value = 0.6944 > 0.05) and there is no causality relationship existing between external debt and economic growth in Nigeria. The study therefore recommends that the federal government should acquire external debt largely for economic reasons rather than social or political reasons. This would increase the Gross Domestic Product (GDP) of the nation.

A strategy to decelerate and capture a spinning object by a dual-arm space robot

With the increasing requirement of grasping the non-cooperative objects in space by space robots, this paper introduces a new strategy operated by a dual-arm space robot. The strategy includes path planning to capture a spinning target, hybrid control of the motion and the contact force for the end-effectors, coordinated control of the base attitude, and parameter identification of the spinning target during the capture phase. Notably, a pair of proper contact forces can be applied to the two grasp points of the spinning target by the two manipulators, which can decelerate the spinning speed of the target and be utilized to identify the target's moment of inertia around its spinning axis. Considering the non-cooperative situation with the spinning target like a defunct satellite, the uncertainties of the space robot and the target, such as parameters of mass and moment of inertia, are concerned in the design of the Sliding Mode Controller (SMC) with good robustness. Moreover, due to the coupling movement of the base and arms of a dual-arm space robot, the base attitude will be simultaneously maintained by the mounted reaction wheels during the capture operation for good communications and effective solar energy collection. The post-capture process is also presented in the paper to bring the entire system of the space robot and the target into stationary status. To compare the system performance against the uncertainties by different controllers, PID-type Computed Torque Controller (CTC) and SMC are designed together for comparison. When the uncertainties of the mass and the moment of inertia are applied to the system, the simulation results show that SMC has better performance against the uncertainties by delivering higher accuracy of the tracking errors to the desired trajectories than CTC.

Propagation and transformation of a light beam on a curved surface

Starting from the wave equation with a non-zero space curvature, a generalized coordinate-independent expression for the evolution of a light beam on a curved space is derived. By defining the propagation axes, the expression reduces to integrable Green functions without an inevitable singular point. With a Gaussian incident field, the stationary status and refocusing effect of the light field on different shapes of curved surfaces are discussed. Different from a constant diffusion behavior in a flat space, the field experiences a periodical diffraction and refocusing spontaneously with no additional optical elements. To be more specific, we noticed that the laser field on a curved surface experiences a fractional Fourier transform, with a propagation angle to be the transform order. We hope our theoretical results can provide some references for the practical application in a curved surface space.

Addressing Non-linear System Dynamics of Single-Strand RNA Virus-Host Interaction.

Positive single-strand ribonucleic acid [(+)ssRNA] viruses can cause multiple outbreaks, for which comprehensive tailored therapeutic strategies are still missing. Virus and host cell dynamics are tightly connected, generating a complex dynamics that conveys in virion assembly to ensure virus spread in the body. Starting from the knowledge of relevant processes in (+ss)RNA virus replication, transcription, translation, virions budding and shedding, and their respective energy costs, we built up a systems thinking (ST)–based diagram of the virus–host interaction, comprehensive of stocks, flows, and processes as well-described in literature. In ST approach, stocks and flows are expressed by a proxy of the energy embedded and transmitted, respectively, whereas processes are referred to the energy required for the system functioning. In this perspective, healthiness is just a particular configuration, in which stocks relevant for the system (equivalent but not limited to proteins, RNA, DNA, and all metabolites required for the survival) are constant, and the system behavior is stationary. At time of infection, the presence of additional stocks (e.g., viral protein and RNA and all metabolites required for virion assembly and spread) confers a complex network of feedbacks leading to new configurations, which can evolve to maximize the virions stock, thus changing the system structure, output, and purpose. The dynamic trajectories will evolve to achieve a new stationary status, a phenomenon described in microbiology as integration and symbiosis when the system is resilient enough to the changes, or the system may stop functioning and die. Application of external driving forces, acting on processes, can affect the dynamic trajectories adding a further degree of complexity, which can be captured by ST approach, used to address these new configurations. Investigation of system configurations in response to external driving forces acting is developed by computational analysis based on ST diagrams, with the aim at designing novel therapeutic approaches.

Пороговость и двоичные божества как покровители древнего мореплавания. Обрядово-мифологический аспект

Статья посвящена выявлению типов двоичных божеств в контексте их взаимосвязи с мореплаванием древности, представляющих пограничное состояние, связанное с качествами переходности. Выявляются слои их символизма, происходящие из сложившейся системы морских обрядов, с учетом вплетения рассматриваемых божеств в индоевропейский солярный миф эпохи бронзы, воплощающий, в первую очередь, двоичность космоса. Семантика небесных близнецов и двуликого бога Януса фокусируется на пороговых качествах, которые требуют защиты. Диоскуры-Ашвины не столько спасают солнце из нижнего мира, сколько обеспечивают безопасность перехода: пограничное состояние опасно не менее, чем нижний мир. И если Диоскуры выступают стражами границы ввиду полярности, а также с учетом динамики соответствующего мифа (они разделены и могут путешествовать по разным сферам Оси Мира), то Янус выполняет идентичную функцию, но исходя из своего стационарного статуса – он «разрешает» солнцу проход. Римский Янус концентрирует в себе свойства «пересечения» пространства-времени, из которого следует четырех-, пятиликость божеств данного типа. Солярный сюжет разворачивается, соответственно, на уровне микрокосма: и Янус, и Диоскуры мифопоэтизируются как покровители тех, кто находится в пограничном состоянии, то есть путешественников и мореплавателей.

The transient changing of forces in interrupted milling

The knowledge of cutting force in practical technology is increasingly important due to the growing quality and performance requirements. Therefore, especially in the case of milling, it also represents an important research area of cutting theory. The aim of the research in the project presented here was the study of transient processes assumed in milling. For this purpose, a model that describes cutting force in interrupted cutting realistically was developed. According to the initial hypothesis, cutting force reaches a stationary status in a finite time due to the fact that the thermodynamic processes of deformation are time consuming. This influences the energy characteristics of cutting significantly in the case of milling. It was assumed that the transient increase of cutting force can be described by a formula where Kienzle’s force formula is supplemented by an exponential function. The validation of this force model was performed by force measuring during the machining of normalized C-steel of C45 quality. One tool insert was used in the face milling tool. The measurements justified the applicability of the model; the Pearson index of the correlation was R2 > 0.9, moreover, it was higher than 0.95 in many cases.

Changes of Serum IL-6, IL-17, and Complements in Systemic Lupus Erythematosus Patients.

Cytokines activation and low complement levels are common in systemic lupus erythematosus (SLE) patients. This study is aimed to explore the relationship and clinical significance of cytokines and complements with SLE activity. Serum samples of 140 SLE patients and 36 age- and gender-matched healthy controls (HC) were collected. Serum interleukin (IL)-6, IL-17, high-sensitivity C-reactive proteins (hsCRP), and complements (C3, C4) were measured in all samples. These patients were divided into 3 subgroups based on clinical disease activity with SLE Disease Activity Index 2000 (SLEDAI-2K): stationary status subgroup, mild activity subgroup, and moderate/severe activity subgroup. The serum IL-6, IL-17, and hsCRP levels in SLE patients (4.72 ± 0.28 pg/mL, 23.34 ± 1.32 pg/mL, and 4.78 ± 0.34 mg/mL) were significantly higher than those in the HC group (1.51 ± 0.05 pg/mL, 18.28 ± 1.93 pg/mL, and 1.32 ± 0.29 mg/mL), whereas C3 and C4 levels in SLE patients (0.80 ± 0.28 and 0.21 ± 0.08 g/L) were significantly lower than those in the HC group (1.49 ± 0.08 and 0.36 ± 0.02 g/L). A positive correlation was noted between the SLEDAI-2K scores and serum IL-6, IL-17, and hsCRP levels. These results support the proinflammatory cytokines and complements in the pathogenesis of SLE. The serum IL-6, IL-17, and hsCRP levels were correlated with the disease activity.

PIV measurements in near-wake turbulent regions

Particle image velocimetry (PIV) is a non-intrusive optical diagnostic and must be made of the seedings (foreign particles) instead of the fluid itself. However, reliable PIV measurement of turbulence requires sufficient numbers of seeding falling in each interrogation window of image. A gray-level criterion is developed in this work to check the attainment of statistically stationary status of turbulent flow properties. It is suggested that the gray level of no less than 0.66 is used as the threshold for reliable PIV measurements in the present near-wake turbulent regions.

Prevalence of Kaposi\u2019s sarcoma-associated herpesvirus in Uygur and Han populations from the Urumqi and Kashgar regions of Xinjiang, China

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the infectious etiologic agent associated with Kaposi’s sarcoma (KS), primary effusion lymphoma, and multicentric Castleman disease. It has been shown that high KSHV prevalence and high incidence of both classic KS and AIDSassociated KS are found mostly among people of Uygur ethnicity in Xinjiang, while people of Han ethnicity in Xinjiang have a higher KSHV seroprevalence than those of other Han populations in mainland China. However, it is still unclear why there is such geographical and population variation in KSHV distribution in China. In this work, we focused on the populations in the Kashgar region and Urumqi area, where a total of 1294 research subjects were randomly selected to investigate the potential correlation between KSHV prevalence and different ethnicities in endemic areas of Xinjiang, and to determine risk factors that may affect KSHV infection rates or KS incidence. We identified a high seroprevalence of KSHV and high peripheral blood DNA infection in the general Uygur and Han populations in both Urumqi and Kashgar regions of Xinjiang, and determined that advancing age, low education level, and stationary population status affect KSHV infection rates. Further, KSHV-positive Uygur participants were shown to have higher prevalence of neutralizing antibodies and neutralizing antibody titers than KSHV-positive Han participants.

Performance Investigation of Spatial Modulation Systems Under Non-Stationary Wideband High-Speed Train Channel Models

In this paper, the bit error rate (BER) performance of a new multiple-input-multiple-output technique, named spatial modulation (SM), is studied under a novel non-stationary wideband high-speed train (HST) channel model in different scenarios. Time-varying parameters obtained from measurement results are used to configure the channel model to make all results more realistic. A novel statistic property called the stationary interval in terms of the space-time correlation function is proposed to describe the channel model’s time-varying behavior. The accurate theoretical BER expression of SM systems is derived under the time-varying wideband HST channel model with the non-ideal channel estimation assumption. The simulation results demonstrate that the BER performance of SM systems shows a time-varying behavior due to the non-stationary property of the employed HST channel model. The system performance can maintain a relative stationary status within the specified stationary interval. It can also be observed that the BER performance of SM systems under the HST channel model is mainly affected by the correlation between sub-channels, inter-symbol-interference, Doppler shift, and channel estimation errors.

Analysis of river health variation under the background of urbanization based on entropy weight and matter-element model: A case study in Huzhou City in the Yangtze River Delta, China

Maintaining the health of the river ecosystem is an essential ecological and environmental guarantee for regional sustainable development and one of the basic objectives in water resource management. With the rapid development of urbanization, the river health situation is deteriorating, especially in urban areas. The river health evaluation is a complex process that involves various natural and social components; eight eco-hydrological indicators were selected to establish an evaluation system, and the variation of river health status under the background of urbanization was explored based on entropy weight and matter-element model. The comprehensive correlative degrees of urban river health of Huzhou City in 2001, 2006 and 2010 were then calculated. The results indicated that river health status of the study area was in the direction of pathological trend, and the impact of limiting factors (such as Shannon's diversity index and agroforestry output growth rate) played an important role in river health. The variation of maximum correlative degree could be classified into stationary status, deterioration status, deterioration-to-improvement status, and improvement-to-deterioration status. There was a severe deterioration situation of river health under the background of urbanization.

A User Proprietary Obfuscate System for Positions Sharing in Location-Aware Social Networks

A user’s trajectory can be maliciously monitored by adversaries when they share the positions in location-aware social networking applications which require users to update their own locations continuously. An adversary infers user’s locations from the trajectories, and gleans user’s private information through them via location-aware social networking applications and public available geographic data. In this paper, we propose a user proprietary obfuscate system to suit situations for position sharing and location privacy preserving in location-aware social network. Users transform the public available geographic data into personal obfuscate region maps with pre-defined profile to prevent the location leaking in stationary status. Our obfuscation with size restricted regions method tunes user’s transformed locations fitting into natural movement and prevents unreasonable snapshot locations been recorded in the trajectory.

English

The scope of this paper is to explore the relationship between tourism development and carbon emission in Maldives. Data used are already published data for Maldives tourism development and carbon emission. Individual Model for tourism development indicators and combined model of all the indicators were used to test the relationship. Unit root test was used to test the stationary status of the data. Empirical tests were performed using Ordinary Least square Method. Unit root results suggest that data are stationary at first differentiation. Regression results show very significant positive correlation between tourism development indicators and carbon emission. The relationship between carbon emission and tourism development shows very directional positive relationship. The results suggest growth of tourism and development of the industry is one major factor driving the carbon emission in Maldives. To reduce the carbon emission to achieve the goal of becoming the first carbon natural country, government could encourage opening of guest houses with more simulative rules by increasing the number of beds without increasing the number of resorts, increasing number of international airports, limiting domestic transfers and developing tourist sites to increase the output of the industry. Key words: Tourism development, carbon emission, Maldives.