Transient Period Research Articles

Approach to the Patient: Diagnosis of Cushing Syndrome.

Cushing syndrome results from supraphysiological exposure to glucocorticoids and is associated with significant morbidity and mortality. The pathogenesis includes administration of corticosteroids (exogenous Cushing syndrome) or autonomous cortisol overproduction, whether or not ACTH-dependent (endogenous Cushing syndrome). An early diagnosis of Cushing syndrome is warranted; however, in clinical practice, it is very challenging partly because of resemblance with other common conditions (ie, pseudo-Cushing syndrome). Initial workup should start with excluding local and systemic corticosteroid use. First-line screening tests including the 1-mg dexamethasone suppression test, 24-hour urinary free cortisol excretion, and late-night salivary cortisol measurement should be performed to screen for endogenous Cushing syndrome. Scalp-hair cortisol/cortisone analysis helps in the assessment of long-term glucocorticoid exposure as well as in detection of transient periods of hypercortisolism as observed in cyclical Cushing syndrome. Interpretation of results can be difficult because of individual patient characteristics and hence requires awareness of test limitations. Once endogenous Cushing syndrome is established, measurement of plasma ACTH concentrations differentiates between ACTH-dependent (80%-85%) or ACTH-independent (15%-20%) causes. Further assessment with different imaging modalities and dynamic biochemical testing including bilateral inferior petrosal sinus sampling helps further pinpoint the cause of Cushing's syndrome. In this issue of "Approach to the patient," the diagnostic workup of Cushing syndrome is discussed with answering the questions when to screen, how to screen, and how to differentiate the different causes. In this respect, the latest developments in biochemical and imaging techniques are discussed as well.

Numerical transient modeling of a flat plate solar collector

The present study deals with numerical simulation of a typical flat plate solar collector. The transient two-dimensional governing differential equations of absorber plate, working fluid and glass cover were formulated to describe the thermal problem of the collector. The governing differential equations were solved numerically using Finite Differences Method and the transient problem was formulated using implicit scheme which gives a stable solution for any grid size and time step. The two-dimensional temperature distribution in absorber plate was achieved at 2211 nodes at every 10 s of the simulation period that extended for 1800 s. The variation of fluid exit temperature and glass cover temperature were also estimated. The estimation of top heat loss coefficient and collector efficiency becomes possible using the temperature distributions of absorber plate and working fluid along with cover temperature. The variations of mean plate temperature, fluid exit temperature, cover temperature, top heat loss coefficient and collector efficiency were drawn during the simulation period. Temperature distribution contours were also drawn at selected time intervals and irradiance values. It was concluded that the top heat loss coefficient of the solar collector is a strong function of the irradiance and working fluid mass flow rate. Increasing the value of mass flow rate shortened the transient period of the solar collector and rendered the transient curves of the collector parameters more flat. The study can be useful for further understanding the complex transient two-dimensional thermal problem occurring in flat plate solar collectors.

WE7.10 Traumatic abdominal wall hernia and CT missed severe intra-abdominal injuries

Abstract Despite traumatic abdominal wall hernia (TAWH) being a rare entity, the incidence of associated intra-abdominal injuries is extremely common. With only few cases published, TAWH remains a diagnostic as well as a therapeutic challenge. We present an obese 47-year-old female, front seat passenger, that was transferred to our hospital from a neighbouring DGH with a diagnosis of TAWH after a 30mph road traffic collision. On arrival, she was haemodynamically stable, abdominal examination showed a large hernia, extensive bruising but the abdomen was otherwise unremarkable. The CT performed before transfer showed a large hernia but no obvious other injury, no free fluid or gas was identified. Hernia repair was planned for the following day. Overnight there was a transient period of hypotension responsive to transfusion of multiple RBC units. The surgical approach was over the hernia site. Within the sac a transected end of small bowel was found and so laparotomy was undertaken, which demonstrated a bucket handle mesenteric tear of terminal ileal mesentery with infarction of 20 cm of small bowel and a complete transverse tear of mid sigmoid colon and its mesentery. Remarkably there was no intraperitoneal contamination from either injury. Our clinical case highlights that although the CT scan is the gold standard for initial diagnosis of intra-abdominal injuries in TAWH, these can still be missed. To note that failure to make a timely diagnosis can result in delayed complications with significant morbidity and mortality. Therefore, a high clinical suspicion, despite of negative imaging, is crucial to provide appropriate management.

Effects of waveform shape and electrode material on KiloHertz frequency alternating current block of mammalian peripheral nerve

ObjectivesKiloHertz frequency alternating current waveforms produce conduction block in peripheral nerves. It is not clearly known how the waveform shape affects block outcomes, and if waveform effects are frequency dependent. We determined the effects of waveform shape using two types of electrodes.Materials and methodsAcute in-vivo experiments were performed on 12 rats. Bipolar electrodes were used to electrically block motor nerve impulses in the sciatic nerve, as measured using force output from the gastrocnemius muscle. Three blocking waveforms were delivered (sinusoidal, square and triangular) at 6 frequencies (10–60 kHz). Bare platinum electrodes were compared with carbon black coated electrodes. We determined the minimum amplitude that could completely block motor nerve conduction (block threshold), and measured properties of the onset response, which is a transient period of nerve activation at the start of block. In-vivo results were compared with computational modeling conducted using the NEURON simulation environment using a nerve membrane model modified for stimulation in the kilohertz frequency range.ResultsFor the majority of parameters, in-vivo testing and simulations showed similar results: Block thresholds increased linearly with frequency for all three waveforms. Block thresholds were significantly different between waveforms; lowest for the square waveform and highest for triangular waveform. When converted to charge per cycle, square waveforms required the maximum charge per phase, and triangular waveforms the least. Onset parameters were affected by blocking frequency but not by waveform shape. Electrode comparisons were performed only in-vivo. Electrodes with carbon black coatings gave significantly lower block thresholds and reduced onset responses across all blocking frequencies. For 10 and 20 kHz, carbon black coating significantly reduced the charge required for nerve block.ConclusionsWe conclude that both sinusoidal and square waveforms at frequencies of 20 kHz or higher would be optimal. Future investigation of carbon black or other high charge capacity electrodes may be useful in achieving block with lower BTs and onsets. These findings will be of importance for designing clinical nerve block systems.

Competition rather than facilitation affects plant performance across an abiotic stress gradient in a restored California salt marsh

The Stress Gradient Hypothesis predicts facilitation will become more important than competition where abiotic stress is high, and the framework successfully predicts positive interactions between species in many systems. Fewer studies have focused on intraspecific facilitation, and to our knowledge none examine intraspecific interactions in Pacific Coast salt marshes of North America. We used two species that tend to occur in large, monospecific patches to test for intraspecific facilitation in a restored California marsh, where tides and evaporation during summer create moisture and salinity gradients across elevation. We tested performance of Frankenia salina or Jaumea carnosa in restoration plots using two treatments: clustered plantings to promote facilitation, and widely spaced plantings to limit interaction between individuals. We characterized the soil water potential gradient and measured plant survival, cover, physiology, and susceptibility to herbivory across elevation and planting treatments. Soil water potential declined sharply with elevation, suggesting plant stress should be higher upslope. However, tissue water potential was unaffected by elevation, and survival was high—suggesting growing conditions remained benign. A seawater addition treatment did not alter the response of plants or plant interactions to the abiotic gradient. At 19 months, intraspecific competition prevailed across the entire elevation gradient for both species, with less transplant cover in clustered plantings. However, clustered Frankenia fared better during a transient period of heavy rabbit herbivory. Aside from this temporary benefit, clustering did not reduce stress and strongly suppressed growth—suggesting that restoration designs for the high marsh should minimize competition.

Spatiotemporal dynamics of EEG microstates in four- to eight-year-old children: Age- and sex-related effects

The ultrafast spatiotemporal dynamics of large-scale neural networks can be examined using resting-state electroencephalography (EEG) microstates, representing transient periods of synchronized neural activity that evolve dynamically over time. In adults, four canonical microstates have been shown to explain most topographic variance in resting-state EEG. Their temporal structures are age-, sex- and state-dependent, and are susceptible to pathological brain states. However, no studies have assessed the spatial and temporal properties of EEG microstates exclusively during early childhood, a critical period of rapid brain development. Here we sought to investigate EEG microstates recorded with high-density EEG in a large sample of 103, 4–8-year-old children. Using data-driven k-means cluster analysis, we show that the four canonical microstates reported in adult populations already exist in early childhood. Using multiple linear regressions, we demonstrate that the temporal dynamics of two microstates are associated with age and sex. Source localization suggests that attention- and cognitive control-related networks govern the topographies of the age- and sex-dependent microstates. These novel findings provide unique insights into functional brain development in children captured with EEG microstates.

The effect of the multimodal intervention including an automatic notification of catheter days on reducing central line-related bloodstream infection: a retrospective, observational, quasi-experimental study

BackgroundA central venous catheter (CVC) is an important medical device, but it could be preceding infection and the risk of central line-associated bloodstream infection (CLABSI). CLABSI is a common healthcare-associated infection but results in high cost and mortality; therefore, various efforts to reduce CLABSI have been attempted.MethodsThis is a retrospective, observational, quasi-experimental study in the intensive care unit (ICU) of a single tertiary care hospital. We reviewed and analysed the data of CLABSI rates and days from the insertion to the removal of the temporary CVC between January 2018 and June 2021 with transient periods over 9 months. Sequentially, all patients with the CVC in the ICU underwent the following interventions: maximal barrier precaution, automatic notification of catheter days and 2% chlorhexidine gluconate bathing. A segmented regression analysis of interrupted time series was conducted to compare the CLABSI rates before and after the introduction of multimodal interventions. During study periods, the impact of interventions on CLABSI was evaluated using multivariate logistic regression analyses.ResultsA total of 76,504 patient-days, 28,312 catheter days and 66 CLABSI cases were reviewed in ICU-hospitalised patients. As additional interventions, the CLABSI rate declined from 3.1 per 1000 CVC days to 1.2 per 1000 CVC days in post-interventions. In the pre-intervention and post-intervention periods, 4146 patents had one more short-term CVC. In the multivariate logistic regression analyses, multimodal intervention was one of determinants reducing CLABSI rates (odds ratio (OR), 0.52 [95% confidence interval {CI}, 0.28–0.94]). Indwelling time of CVC over 10 days was the risk factor for CLABSI rates (OR, 6.27 [95% CI, 3.36–12.48]). Of the three interventions, the automatic notification of catheter days was associated with decreased median monthly total CVC days and duration of CVC days per patient.ConclusionsMultidisciplinary and evidence-based interventions could lead to a decrease in the CLABSI rates. Moreover, the automatic notification of catheter days of the electronic medical healthcare system has shortened the time of indwelling CVC.

Microstructure Evolution of Nanosecond Laser Annealed Si/Si1-XGex/Si Structures

Si1-xGex has a liquidus temperature lower than the melting point of Si [1], and the liquidus temperature decrease with the Ge concentration. Here, we investigate the possibility of selectively melting a buried Si1-xGex layer in Si during annealing. However, as Si and Ge are miscible over the entire composition range [2], Ge can diffuse into the Si matrix before such melting occurs. To avoid this effect, we used a nanosecond Laser Annealing (nLA) which allows raising the temperature at a fast heating rate (1010 K/s).Pseudomorphic Si1-xGex layers [3] of 20 nm for x = 0.3 or 0.4, and of 15 nm for x= 0.5 (corresponding to Delta Temperature = Tmelt Si – Tliq Si1-xGex of 60°C, 95°C, and 139°C respectively) were grown on 300 mm (001)-Si wafers. The Si1-xGex layers were covered with 17 nm of Si. Selected areas of the wafers were irradiated with nLA (308 nm wavelength and pulse duration of 160 ns) at different energy densities (ED). After laser annealing, the samples were characterized by X-Ray Diffraction (XRD), SP2 Haze, Atomic Force Microscopy (AFM), and Scanning Electron Microscopy (SEM).In Fig. 1a, we show the in-situ time-resolved reflectometry (TRR) recorded during the laser annealing. For ED lower than the ones indicated by the dotted lines, the surface reflectivity remains unchanged during annealing. For higher ED, the reflectivity increases sharply for a transient period ranging from 100 ns to 380 ns. This is typically associated with a melting process [4].In Fig. 1b, we display the (004) XRD scans for the three studied structures. For low ED, the Si1-xGex diffraction pattern may present a gradual reduction in intensity. For an ED higher than a threshold ED (different for each substrate), we report on a sharp transition of the Si1-xGex peak to a characteristic position of lower Ge concentration. This new characteristic peak increases in intensity with ED. The peak gradually shifts towards lower Ge concentrations for the higher tested EDs.In Fig. 1c, we show the measurements of the SP2 haze and AFM Root Mean Square (RMS) roughness. For ED lower than a threshold ED (zone 1), the roughness is low, characteristic of an unmodified surface. For intermediate ED (zone 2), the roughness rises abruptly. It then gradually falls with increasing ED to enter a third zone showing constant values.In Fig. 1d, we display SEM micrographs using secondary electrons (SE) and backscattered electrons (BSE). The SE provides topographic information and BSE provides additional chemical information from a higher depth range in the substrate. In the stacks with Si0.7Ge0.3 and Si0.6Ge0.4 layers, four-fold structures with symmetry along <110>-directions are observed in the images obtained using SE and BSE. For the stack with Si0.5Ge0.5, these formations are observed only with the BSE.The presented results show that using AFM, Haze, and SEM, surface modifications are detected at a lower ED compared to intensity rise obtained by TRR, providing then a higher sensitivity to identify the melt onset. By XRD, the first modifications are detected at a higher ED compared to TRR, wherein a larger modified volume is likely required to provide enough diffraction intensity. The characteristic Si1-xGex peak in the diffraction diagrams (Fig. 1b), abruptly appearing at a threshold ED for each stack, is associated with the formation of the four-fold structures in the SEM micrographs (Fig. 1d). Therefore, it is a signature of its composition/structure. The SEMs have also shown that for the Si1-xGex layers with up to 40 at% Ge, the Si1-xGex and top Si layers are both molten at the detected melt onset. In contrast, for the stack with Si0.5Ge0.5, the four-fold structure is only detected with BSE, evidencing a buried transformation. Therefore, for our experimental setup, a minimum Ge content of 50 at% or a Delta Temperature of 139°C was necessary to obtain a buried melted layer.

On-Demand Nanoliter Sampling Probe for the Collection of Brain Fluid.

Continuous fluidic sampling systems allow collection of brain biomarkers in vivo. Here, we propose a new sequential and intermittent sampling paradigm using droplets, called Droplet on Demand (DoD). It is implemented in a microfabricated neural probe and alternates phases of analyte removal from the tissue and phases of equilibration of the concentration in the tissue. It allows sampling droplets loaded with molecules from the brain extracellular fluid punctually, without the long transient equilibration periods typical of continuous methods. It uses an accurately defined fluidic sequence with controlled timings, volumes, and flow rates, and correct operation is verified by the embedded electrodes and a flow sensor. As a proof of concept, we demonstrated the application of this novel approach in vitro and in vivo, to collect glucose in the brain of mice, with a temporal resolution of 1-2 min and without transient regime. Absolute quantification of the glucose level in the samples was performed by direct infusion nanoelectrospray ionization Fourier transform mass spectrometry (nanoESI-FTMS). By adjusting the diffusion time and the perfusion volume of DoD, the fraction of molecules recovered in the samples can be tuned to mirror the tissue concentration at accurate points in time. Moreover, this makes quantification of biomarkers in the brain possible within acute experiments of only 20-120 min. DoD provides a complementary tool to continuous microdialysis and push-pull sampling probes. Thus, the advances allowed by DoD will benefit quantitative molecular studies in the brain, i.e., for molecules involved in volume transmission or for protein aggregates that form in neurodegenerative diseases over long periods.

Realistic operation of two residential cordwood-fired outdoor hydronic heater appliances—Part 1: Particulate and gaseous emissions

ABSTRACT This study investigated how heat demand and fuel loading affect the emissions from outdoor wood-fired hydronic heaters by testing two such appliances using an integrated-duty cycle test method. This test included transient operating conditions, such as cold and hot-starts and modulation between 15 and 100% of maximum rated output. Emission values indicate transient operating conditions produce higher emissions than steady state operation. Cold starts resulted in elevated particulate matter emission factors for both appliances; in one case the particulate matter emission factor for this period was >3500 mg/MJ, which represented emissions 20 times the average value. Additionally, when heat demand was cycled—elevated CO emission factors were measured, with values >5000 mg/MJ for both appliances and more than 3 times the appliance averages, respectively. It follows that the appliance average particulate matter emission factors and CO emission factors were not representative of the actual EF values during these transient periods. In contrast, methane emission factors were relatively stable throughout all tested combustion conditions; however, they were much higher than oil-fired appliances are therefore should not be ignored. These findings demonstrate that wood-fired hydronic heater emissions during transient operating conditions can be significantly greater than emissions during steady-state test conditions, such as those used in typical certification tests. Consequently, certification test values for particulate matter and CO emission factors may significantly underestimate the actual emissions of these appliances when operated in a home. Use of integrated duty-cycle test protocols that capture cold-starts and reloading are better for representing in-use operations of wood-fired hydronic heaters and provide more realistic emissions and delivered efficiency measurements. Implications: In this work we provide information on the particulate and gaseous emissions from two wood fired outdoor hydronic heaters. The units were tested using an integrated duty cycle test method that captured cold starts, reload, cyclic and modulating periods between 15 and 100% of maximum rated output. The data and results show a much higher emission factor than those reported by current certification test methods but are more representative of how the units operate in the field.

Numerical investigations of hydraulic transient and thermodynamic characteristics of water flow impacting air pocket inside pipe based on CLSVOF

Abstract The hydraulic transient and thermodynamic characteristics of water flows impacting an air pocket at the vertical end of an elbow pipe are investigated. The CLSVOF (coupled level-set and volume of fluid) and URANS (unsteady Reynolds-averaged Navier–Stokes) equations with energy equation are implemented, where the RNG (Re-Normalization Group) k–ε turbulence model is adopted and the pressure–density equation is introduced to allow for the water-phase compressibility. All numerical predictions are consistent with the experimental in the literature. The evolution characteristics and mechanism of the water–air interface are analyzed based on the Froude number and dimensionless water–air mixing degree. For air-pocket Type I and Type II with the water–air mixing degree threshold of 10%, based on the first law of engineering thermodynamics and related process laws and basic theory of statistics, the applicability of the ideal gas model in the thermodynamic process of air pocket, the polytropic index regulation in the evolution process and its association with relevant typical thermodynamic processes are systematically analyzed. The polytropic index of air-pocket Type I fluctuates a little with the averaged median of 1.35 in different transient periods under different initial pressure conditions, while it fluctuates largely with the averaged median of 1.26 and 1.21 under the low and the high initial pressure conditions, respectively.

Agent-based model generating stylized facts of fixed income markets

We develop an agent-based model (ABM) of a financial market with multiple assets belonging either to the fixed income or equity asset classes. The aim is to reproduce the main stylized facts of fixed income markets with regards to the emerging dynamics of the yield curves. Our ABM is rooted in the market model of Kaizoji et al. (J Econ Behav Organ 112:289–310, 2015) formulated with two types of traders: the rational and risk-averse fundamentalist investors and the noise traders who invest under the influence of social imitation and price momentum. The investors involved in the present market model diversify their investments between a preferred stock equivalent to a perpetual bond and multiple bonds of selected maturities. Among those, a zero-coupon bond provides a constant rate of return, while the prices of the coupon-paying bonds are determined at each time step by the equilibrium between the investors’ demands and supplies. As a result, the ABM creates an evolving yield curve determined by the aggregate impact of the traders’ investments. In agreement with real markets, it also produces transient turbulent periods in the prices’ time series as well as a humped term structure of volatility. We compare the dynamics arising from different processes governing the risk-free rate with those of the historical US Treasury market. Introducing Vasicek’s model of interest rates to both synthetic and empirical rates demonstrates the capacity of our ABM in reproducing the main characteristics of the surface of autocorrelation of the volatilities of the yields to maturity of the US Treasury bonds for the selected time-frame.

Numerical simulation of single aluminum droplet evaporation based on VOF method

In order to explore the law of single aluminum droplet evaporation process in argon, based on the VOF method, this paper carried out a corresponding two-dimensional transient multiphase flow numerical simulation. The evaporation process of droplet behavior in forced convection environment is compared and analyzed, and the influences of gas velocity on evaporation rate, the change of the droplet temperature and concentration boundary layer, and the variation of the velocity field around the droplet are studied. The research results showed that droplet evaporation can be divided into transient variation period and steady-state period. As the gas velocity increased from 2 m/s to 5 m/s, the evaporation rate at the transient variation period of aluminum droplets was increased by 22%–36%, and the evaporation rate at the steady-state stage was increased by 16%–33%; At 2 m/s, the temperature boundary layer on the windward and leeward sides of the droplet was thicker than the concentration boundary layer, indicating that the temperature diffusion was greater than the concentration diffusion; In addition, when the airflow around the droplet, the double row of vortices periodically fell off from the upper and lower sides of the droplet with opposite rotation direction and regular arrangement. With the mutual interference and influence between shedding vortices, Karman vortex street was formed, and the formation of the Karman vortex street became more obvious with the increase of the Reynolds number. The research results of this paper could provide reference for the unsteady numerical simulation of aluminum droplets combustion with chemical reaction in the future.

Using Agarwal analytical approach with superposition rate and time solutions to analyze multi and single well systems

There are many RTA (Rate Transient Analysis) methods available to analyze wells producing from unconventional formations. The approach of Agarwal (2010) is one of the RTA techniques which have gained an increasing interest due to its simplicity, flexibility, and wide range of applications. In this study, the approach of Agarwal (2010) was adopted to analyze not only single well systems but also multi-well systems by using three different equations. These equations were then integrated with the principle of superposition rate rather than conventional superposition time. By using two field cases, the accuracy of the proposed approaches was validated with current analytical methods and reservoir simulation. The first case represents a multi-well system in which the wells producing with a fixed flowing pressure were put on production at the same time. The operating conditions were then relaxed in the second case by allowing the wells to have different production starting times and varying production profiles.Additionally, this work examined in details the ability of the superposition rate function in converting various production behaviors to their equivalent constant rate solutions. This research clearly shows the advantage of the superposition rate solution over the traditional superposition time function (material balance time) in maintaining the data order in time. Such an advantage makes it easier for the analyst to observe the production changes in well performance in real normal time.Several case studies were used to show how Agarwal (2010) can be utilized to extract different information from boundary-dominated flow period which are useful in the evaluation of reservoir compartmentalization and the effectiveness of infill drilling campaigns. In addition to that, the application of Agarwal (2010) in terms of frac hits evaluation and refracturing operations encountered during the transient flow period was also examined.

“Modeling of Saline Water Intrusion using MODFLOW in Una Coastal Aquifer of Gujarat, India.”

Abstract: Groundwater is the most valuable and extensively dispersed resource on the planet, and unlike any other mineral resource, it is replenished annually by meteoric precipitation. The present study would include simulation and modelling of the problem of seawater intrusion in the Una coastal area of Gujarat. The interrelationships of two miscible fluids in porous media have been widely explored both theoretically and experimentally. Because of the extreme salinity, many agricultural wells are no longer used. This high salinity is a sign of a process known as saltwater intrusion, which occurs mostly in coastal aquifers due to excessive pumping. Modelling software has also been utilized to analyze the behavior of groundwater flow models. Numerical models may simulate diverse groundwater scenarios and link them to groundwater management. To simulate seawater intrusion, MODFLOW-2005, a grid-based variable density-dependent flow model, is used. Water balance research reveals that rainwater recharge is the aquifer's primary input. To compute the water level in the area and estimate the position of the seawater intrusion barrier, the saltwater intrusion phenomena were simulated using the MODFLOW software combined with the SWI2 package. The model was used to visualize the salinity levels of the coastal aquifer's groundwater and their fluctuation over time and space from May 2004 to October 2014. The model was developed for a 10-year stress period with 100-time steps, which included a 5-year steady state and 5 years transient state stress period using the previous 10 years of pre-monsoon and postmonsoon data. This research would assist to describe Pumping's impact on groundwater levels and seawater intrusion was studied. Keywords: MODFLOW, Saltwater Intrusion, Modelling, Numerical Model, Coastal aquifer

Characterization of the Time-Domain Isotopic Beat Patterns of Monoclonal Antibodies in Fourier Transform Mass Spectrometry.

The time-domain transients in the Fourier transform mass spectrometry (FTMS) analysis of monoclonal antibodies (mAbs) are known to exhibit characteristic isotopic beat patterns. These patterns are defined by the isotopic distributions of all gaseous mAb ions present in the FTMS mass analyzer, originating from single or multiple charge states, and from single or multiple proteoforms. For an isolated charge state of a single proteoform, the mAb isotopic beat pattern resembles narrow splashes of signal amplitude (beats), spaced periodically in the time-domain transient, with broad (often exceeding 1 s) "valleys" between them. Here, we reinforce the importance of isotopic beat patterns for the accurate interpretation and presentation of FTMS data in the analysis of mAbs and other large biopolymers. An updated, mAb-grade version of the transient-mediated FTMS data simulation and visualization tool, FTMS Simulator is introduced and benchmarked. We then apply this tool to evaluate the charge-state dependent characteristics of isotopic beats in mAbs analyses with modern models of Orbitrap and ion cyclotron resonance (ICR) FTMS instruments, including detection of higher-order harmonics. We demonstrate the impact of the isotopic beat patterns on the analytical characteristics of the resulting mass spectra of individual and overlapping mAb proteoforms. The results reported here detail highly nonlinear dependences of resolution and signal-to-noise ratio on the time-domain transient period, absorption or magnitude mode spectra representation, and apodization functions. The provided description and the demonstrated ability to routinely conduct accurate simulations of FTMS data for large biopolymers should aid the end-users of Orbitrap and ICR FTMS instruments in the analysis of mAbs and other biopolymers, including viruses.

Performance guaranteed attack reconstruction for cyber–physical systems: A new intermediate estimator-based framework

For attack reconstruction issue of cyber–physical systems (CPSs), it is a challenge to guarantee online computational efficiency and reconstruction accuracy simultaneously, especially for cases with actuator attacks. However, most existing approaches are only focused on sensor attacks. This brief paper studies the multiple attack reconstruction problem for CPSs. A new projected intermediate estimator is proposed, where the computation complexity problem is solved by reducing the number of loop iterations significantly via enhancing the designs of loop iteration, termination condition and parameter selection strategy, without sacrificing the attack reconstruction performance. Compared with traditional intermediate estimators, the dependence of linear matrix inequality technique is completely removed, besides, the intrinsic heavy overshooting problem in transient period is effectively alleviated. The application to a networked motion control system verifies the effectiveness and superiority of the presented method.

Autogenic Signals in the Sedimentary Record of Organic Carbon Preservation

The burial of organic carbon (OC) preserves paleoenvironmental archives and drives the evolution of Earth's biogeochemical cycles. While the impact of kinetic heterogeneity on OC preservation has been studied, the effects of sedimentation dynamics remain largely unknown. Here, we incorporate the expected stochastic variability in sedimentation rates into a reactive-transport model, generate predictions for stratigraphic variability of OC burial efficiency, and compare the model outputs to field observations. We find that internal sedimentation dynamics profoundly influence OC preservation efficiencies and create autogenic signals that may obscure signals originated from external forcings. Simulations match observations in terms of power spectra when our model considers transient periods of erosion during net deposition, implying that the manifestation of sedimentation dynamics and their interactions with biogeochemistry in chemostratigraphic records are prevalent in nature. As sedimentary OC records reflect both internal variability and external forcing, they may be used as proxies for past depositional conditions.

A Two-Stage Simultaneous Control Scheme for the Transient Angle Stability of VSG Considering Current Limitation and Voltage Support

Since the wide application of virtual synchronous generators (VSGs), the power grid faces great challenges in the safe and stable operation due to their limited thermal capacity and weak anti-disturbance ability. During transient period, for example, a fault occurs in the transmission line, the VSG may lose the transient angle stability and provoke the current hard limit. Even if the fault is cleared by tripping of line, it still faces the problem of instability and voltage dips. To address this problem, in this paper, the post-fault large-signal model of VSG is derived first via the travelling waves based fault information acquisition. Subsequently, with the effect of both active and reactive power loops taken into account, a two-stage simultaneous control scheme is proposed for improving the transient stability of VSG, while considering the current limitation during fault state and voltage support after fault clearance. This method is fulfilled by mode switching and an additional feedback control based on the fault signal. Finally, the effectiveness of the proposed method under both symmetrical and asymmetrical faults is verified. Moreover, the application of the proposed method in a multiple VSGs system is also verified. Besides, the robustness to parameter mismatch and the feasible operating region for the method are discussed.

On the analysis of plasticity induced crack closure in welded specimens: A mechanism controlled by the stress intensity factor resulting from residual stresses

The aim of this paper is to clarify how and to what extent varied welding residual stresses (WRSes) affect the plane stress plasticity induced crack closure (PICC) simulation. A well-characterized, representative WRS field with tensile and compressive reversals was imported and the predicted PICC results were evaluated against the relevant WRS-free ones. It turned out that instead of WRS typically reported in the literature, there is actually a Kres (stress intensity factor resulting from residual stresses) controlled crack closure mechanism when investigating the PICC behavior in the presence of a WRS field, i.e., WRS influences PICC in the form of Kres. Four major categories where the crack tip was located in different Kres zones were defined using MT (middle tension) and SENT (single edge notch tension) specimens to investigate the mechanism in detail. In summary, the Kres value determined the general steady-state PICC level in the WRS field, i.e., a diminished steady-state opening stress level was predicted in the WRS field with a positive Kres regardless of whether the crack is located in a tensile or a compressive WRS zone, and an elevated value was estimated when the Kres was negative. Besides, the initial transient period was scrutinized that occurred in some WRS scenarios and the concept of primary and secondary plastic wake evolution was proposed to explain its formation. It was found that the transient behavior could be eradicated by tailoring the secondary plastic wake employing appropriate constitutive models and mesh refinement levels. The results attained in the present work provide some guidelines for the WRS-PICC modeling and simulation in the fracture mechanics community.