Explore the vast range of titles available.

Background The effects of diastolic arterial pressure (DAP) and heart rate (HR) on the prognosis of patients with septic shock are unclear, and whether these effects persist over time is unknown. We aimed to investigate the relationship between exposure to different intensities of DAP and HR over time and mortality at 28 days in patients with septic shock. Methods In this cohort study, we obtained data from the Medical Information Mart for Intensive Care IV, which includes the data of adult patients (≥ 18 years) with septic shock who underwent invasive blood pressure monitoring. We excluded patients who received extracorporeal membrane oxygenation (ECMO) or glucocorticoids within 48 h of ICU admission. The primary outcome was mortality at 28 days. Piece-wise exponential additive mixed models were used to estimate the strength of the associations over time. Results In total, 4959 patients were finally included. The median length of stay in the ICU was 3.2 days (IQR: 1.5–7.1 days), and the mortality in the ICU was 12.9%, with a total mortality at 28 days of 15.9%. After adjustment for baseline and time-dependent confounders, both daily time-weighted average (TWA) DAP and HR were associated with increased mortality at 28 days and strong association, mainly in the early to mid-stages of the disease. The results showed that mortality in patients with septic shock was lowest at a DAP of 50–70 mm Hg and an HR of 60–90 beats per minute (bpm). Throughout, a significant increase in the risk of death was found with daily exposure to TWA-DAP ≤ 40 mmHg (hazard ratio 0.99, 95% confidence interval (CI) 0.94–1.03) or TWA-HR ≥ 100 bpm (hazard ratio 1.16, 95% CI 1.1–1.21). Cumulative and interactive effects of harmful exposure (TWA-DAP ≤ 40 mmHg and TWA-HR ≥ 100 bpm) were also observed. Conclusion The optimal ranges for DAP and HR in patients with septic shock are 50–70 mmHg and 60–90 bpm, respectively. The cumulative and interactive effects of exposure to low DAP (≤ 40 mmHg) and tachycardia (≥ 100 bpm) were associated with an increased risk of death.

The trace elements in quartz, Al and Ti, contain considerable information about mineral genesis, and determining their concentrations is of great importance in geology. Electron probe microanalysis has the advantages of non-destructive testing and high spatial resolution; however, it is a challenge to improve the accuracy and precision of trace element detection using this method. The important factors affecting accuracy include the fragility of quartz lattices at high beam currents and the methods used to determine the background. In this paper, the peaks of Al-Kα and Ti-Kα, and their backgrounds, were found to exhibit intensity variations at high beam currents and small beam diameters; therefore, it is necessary to select a large beam diameter (up to 20 µm) to avoid variations in intensity at high currents (500 nA). For background determination of Al, a multipoint background method is proposed to determine the background value, which greatly improves the accuracy of the results. For Ti, the choice of background measurement does not affect the result. In addition, it is verified that the background obtained from other quartz samples can be used as the background of an unknown quartz sample, which reduces the analysis time and minimizes sample damage.

The effect of operating conditions on the time-dependent X-ray intensity variation is of great importance for the optimal EPMA conditions for accurate determinations of various elements in carbonate minerals. Beam diameters of 0, 1, 2, 5, 10, 15, and 20 μm, and beam currents of 3, 5, 10, 20, and 50 nA were tested. Ca, Mg, Zn, and Sr were found to be more sensitive to electron beam irradiation as compared to other elements, and small currents and large beam diameters minimized the time-dependent X-ray intensity variations. We determined the optimal EPMA operating conditions for elements in carbonate: 10 μm and 5 nA for calcite; 10 μm and 10 nA for dolomite; 5 μm and 10 nA or 10 μm and 20 nA for strontianite; and 20 nA and 5 μm for other carbonate. Elements sensitive to electron beam irradiation should be determined first. In addition, silicate minerals are preferred as standards rather than carbonate minerals.

From the standpoint of fishery management, an essential component of the basic information upon which policy can be based consists of intelligence from field data and computations. In certain situations, these studies can provide quite a great deal of the necessary information. However, in other situations they have not been able to give unequivocal answers to important questions, especially where several influential factors are involved in the whole jigsaw of the complex fishery system, in which their relative abundance may vary with the intensity of the recruitment effort or with spatial migration. Here, we propose and analyze a reaction–diffusion model for the fish population incorporating time-dependent fishery intensity. Using the traveling wave coordinate, we derive analytical solutions to the model system. Conditions on the system parameters are derived which ensure stability of the system under study. Phase portrait and traveling wave solution are plotted and discussed in order to gain better insights into the spatial movement of the fish population in time.

We study the throughput and losses of a buffer with stochastically dependent service times. Such dependence occurs not only in packet buffers within TCP/IP networks but also in many other queuing systems. We conduct a comprehensive, time-dependent analysis, which includes deriving formulae for the count of packets processed and lost over an arbitrary period, the temporary intensity of output traffic, the temporary intensity of packet losses, buffer throughput, and loss probability. The model considered enables mimicking any packet interarrival time distribution, service time distribution, and correlation between service times. The analytical findings are accompanied by numerical computations that demonstrate the influence of various factors on buffer throughput and losses. These results are also verified through simulations.

Mass concrete structures under long-term loads are susceptible to time-dependent fractures, which pose a threat to their structural integrity and safety. In order to study the crack growth rate of concrete materials under long-term constant load, the data were processed according to the calculation method of fatigue crack growth rate. The relationship between the crack growth rate and strength factor in the stable growth stage was obtained using the Paris formula. The experimental data and theoretical analysis show that the time-dependent fracture curve CMOR(t)-t of the standard three-point bending beam specimens could be divided into three stages. The relationship between the crack propagation rate da/dt(t) in the second stage and the intensity factor K(t) could be well described by the Paris formula. The life of crack growth of a standard three-point curved beam is inversely proportional to the level of constant load. These conclusions can provide data support for further studies on crack extension life under long-term constant load.

A recent parameter identification technique, the local lagged adapted generalized method of moments, is used to identify the time-dependent disease transmission rate and time-dependent noise for the stochastic susceptible, exposed, infectious, temporarily immune, susceptible disease model (SEIRS) with vital rates. The stochasticity appears in the model due to fluctuations in the time-dependent transmission rate of the disease. All other parameter values are assumed to be fixed, known constants. The method is demonstrated with US influenza data from the 2004–2005 through 2016–2017 influenza seasons. The transmission rate and noise intensity stochastically work together to generate the yearly peaks in infections. The local lagged adapted generalized method of moments is tested for forecasting ability. Forecasts are made for the 2016–2017 influenza season and for infection data in year 2017. The forecast method qualitatively matches a single influenza season. Confidence intervals are given for possible future infectious levels.

The validity of the adiabatic approximation in strong field ionization under typical experimental conditions has recently become a topic of great interest. Experimental results have been inconclusive, in part, due to the uncertainty in experimental calibration of intensity. Here we turn to the time-dependent Schrödinger equation, where all the laser parameters are known exactly. We find that the centre of the electron momentum distribution (typically used for calibration of elliptically and circularly polarized light) is sensitive to non-adiabatic effects, leading to intensity shifts in experimental data that can significantly affect the interpretation of results. On the other hand, the transverse momentum spread in the plane of polarization is relatively insensitive to such effects, even in the Keldysh parameter regime approaching γ 3 . This suggests the transverse momentum spread in the plane of polarization as a good alternative to the usual calibration method, particularly for experimental investigation of non-adiabatic effects using circularly polarized light.

The Green-Ampt (GA) model is one of the most widely used analytical methods of slope stability under rainfall. However, it may overestimate the soil water content above the wetting front. In this study, a novel approach to evaluate the time-dependent slope stability during intense rainfall based on a modified GA model is presented, and is known as the stratified Green-Ampt (SGA) model. By considering the stratified soil water content above the wetting front, the soil above the wetting front can be divided into saturated and transitional layers, and the SGA model is used to analyze the infiltration process of intense rainfall into slopes. Thereafter, safety factors (Fs) of infinite and finite slopes are derived using the SGA model. In the analysis of an infinite slope, the conventional limit equilibrium method is adopted to calculate the safety factor; as for a finite slope, the residual thrust method is introduced to obtain the safety factor with sliding mass divided into multiple soil slices. The performance of the SGA model is illustrated in two cases: an infinite slope and the Majiagou landslide as a finite slope. The results indicate that compared to the GA model, the calculated wetting front based upon the SGA model moves faster, and the wetting front depth shows a positive correlation with the slope surface angle and rainfall intensity. The evolution of the safety factor above the sliding surface can be divided into three phases, while the evolution of the safety factor above the wetting front can be divided into two phases. The critical time of the slope reaching a less stable state (safety factor is 1.05) or unstable state (safety factor is 1.00) decreases exponentially with an increase in rainfall intensity. In addition, the rainfall has a significant influence on the design of stabilizing piles for the Majiagou landslide. The presented SGA model appears to be accurate to investigate slope stability during intense rainfall events.