External System Research Articles

Moderating effect of family structure on the relationship between early clinical exposure and emotional labor of nursing students: a cross-sectional study

BackgroundEmotional labor is an essential component of nursing practice and is important for Generation Z nursing students born from the mid-1990s to early 2010s. They will become the backbone of the nursing workforce but present more emotional regulation problems. Studies on emotional labor are limited to clinical nurses and influencing factors at the individual level. The impacts of external systems on emotional labor of nursing students have not been explored. This study aimed to quantify the relationship between early clinical exposure and emotional labor and test the moderating effect of family structure on the relationship.MethodsThe cross-sectional study recruited 467 nursing students using convenience sampling from seven colleges and universities in mainland China. An e-survey created on WJX.CN was used to collect data in January 2023. Emotional labor (surface acting and deep acting) was measured with the Emotional Labor scale. Early clinical exposure (exposure or not and times of exposure) and family structure (nuclear family, extended family, and single-parent family) were assessed with self-reported questions. Descriptive statistics and the linear mixed-effects modeling were used to do the analyses.ResultsThe mean scores of surface acting and deep acting were 26.66 ± 5.66 and 13.90 ± 2.40, respectively. A significant difference in scores of surface acting was not observed for exposure or not, whereas such a significant difference was found for times of exposure. Nursing students from extended families demonstrated significantly lower scores on surface acting while exposed to clinical practice compared with those from nuclear families. Family structure moderated the relationship between times of exposure and surface acting of nursing students when exposed to clinical practice for one time, but the significance disappeared when the times of exposure increased. No significant findings of early clinical exposure on deep acting were observed.ConclusionsEarly clinical exposure influenced emotional labor, and students from extended families were more likely to get benefits from early clinical exposure. Studies are needed to help students from nuclear families get comparable benefits on emotional labor as those from extended families, and improve deep acting by early clinical exposure.

Beam profile characteristics of a Varian linear accelerator across different photon energy levels

Radiotherapy employs variety of energy radiation to destroy cancer cells. A linear accelerator(also called LINAC) is the machine used to delivered external beam radiation therapy.In order to confirm the treatment planning systems that deliver the best radiation to the tumors while sparing the surrounding normal tissues, extensive measurements of dosimetric parameters are part of the commissioning procedure of a LINAC for clinical usage. This work aimed to compare and assess photon beam profiles with respect to penumbra width, symmetry, and beam flatness. Beam profile measurements were performed for this study atTMSS Cancer Center, Bogura, Bangladesh, using a linear accelerator (Varian VitalBeam SN: 5199) with 6MV,10MV and 15MV photon energies for a set of field sizes (4 × 4, 10 × 10 and 20 × 20 cm2) and various reference depths keeping the same environmental conditions. A 3D water phantom, CC13 ionization chamber (SN:18635)as a reference chamber, CC04 ionization field chamber (SN:18616) as a and IBA myQA Accept software version 1.6 were used to measure the profiles of photon energies 6 MV, 10 MV 15 MV respectively. Utilizing the Eclipse (Version: 16.1) external treatment planning system, the profile calculation was carried out. According to the manufacturer's and IEC specifications, the photon beam profile data from the current investigation are compatible, and all of the tolerances fall within the ranges of clinically acceptable tolerance.

Integration of Salesforce with External Systems: Best Practices for Seamless Data Flow

Integration of Salesforce with External Systems: Best Practices for Seamless Data Flow

The Ilizarov Technique: A Dynamic Solution for Orthopaedic Challenges.

The Ilizarov technique is one of the most important tools that is currently employed in bone reconstruction surgeries. Its inception dates back to the mid-20th century and involves various bone reconstruction methodologies implemented using a circular external fixator system devised by G. A. Ilizarov. The key advantages of this approach include the generation of viable new bone via distraction osteogenesis, high union rates, and the functional utilization of the limb during the treatment process. The exploration of distraction osteogenesis phenomenon triggered by tensile stress with the Ilizarov device served as a catalyst for progress in bone reconstruction surgery. Subsequently, the original technique has been utilized alongside several adaptations resulting from the introduction of novel fixation tools and methods of their application, such as hexapod external fixators and motorized intramedullary lengthening nails. It is crucial to possess a precise comprehension of the Ilizarov principles of deformity correction in order to effectively utilize this fixation system. In this article, we will discuss the history of Ilizarov frame, the basic sciences behind it, the mechanical principles governing its use, and the clinical application of the fixation system in our daily practice.

Combustion Test for the Smallest Reciprocating Piston Internal Combustion Engine with HCCI on the Millimeter Scale

Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to structural simplification of the reciprocating piston internal combustion engines under a micro space constraint but has not been adequately verified at the millimeter scale. The study used a millimeter-scale HCCI reciprocating piston internal combustion engine fueled by a mixture of kerosene, ether, castor oil, and isopropyl nitrate for combustion investigation. The test engine with a displacement of 0.547 cc is the smallest reciprocating piston internal combustion engine known to have undergone in-cylinder combustion diagnosis. It is observed that the HCCI combustion mode at the millimeter scale can realize stable combustion with excellent cooperation for the thermodynamic cycle under appropriate structural and operating conditions, which is essentially not inferior to those in conventional-sized reciprocating piston internal combustion engines. This finding helps the next step of scaling down reciprocating piston internal combustion engines.

Disturbance observer based fixed-time tracking control for unmanned aerial helicopters

In this paper, a fixed-time tracking control scheme based on the fixed-time disturbance observer is proposed for a 6-DOF unmanned aerial helicopter (UAH) with flight path constraints and composite disturbances. The composite disturbances are composed of external disturbances and system uncertainties. By using the hyperbolic tangent function, an improved disturbance observer is developed to estimate composite disturbances. Furthermore, a fixed-time back-stepping control method is employed for the position and attitude loops, which enables the UAH to track the expected path within the flight path constraints. Simulation results are given to demonstrate the effectiveness and advantages of the proposed scheme.

Zebra II as A Novel System to Record Electrophysiological Signals in Zebrafish.

Zebrafish and their mutant lines have been extensively used in biomedical investigations, cardiovascular studies, and drug screening. In the current study, the commercial version of the novel system, Zebra II, is presented. The protocol demonstrates electrocardiogram (ECG) acquisition and analysis from multiple zebrafish within controllable working environments. The device is composed of an external and independent perfusion system, a 4-point electrode, temperature sensors, and an embedded electronic system. In previous studies, the device prototype underwent validation against the established iWORX system through several tests, demonstrating similar data quality and ECG response to drug interventions. Following this, the study delved into examining the impact of anesthetic drugs and temperature fluctuations on zebrafish ECG, necessitating instant data evaluation. Thanks to the apparatus's capacity for consistent delivery of anesthetics and drugs, it was possible to extend ECG data collection up to 1 h, markedly longer than the 5 min duration supported by current systems. This paper introduces a pioneering, cloud-based, automated analysis utilizing data from four zebrafish, offering an efficient method for conducting combination experiments and significantly reducing time and effort. The system proved effective in capturing and analyzing ECG, especially in detecting drug-induced arrhythmias in wild-type zebrafish. Additionally, the capability to gather data across multiple channels facilitated the execution of randomized controlled trials with zebrafish models. The developed ECG system overcomes existing limitations, showing the potential to greatly expedite drug discovery and cardiovascular research involving zebrafish.

Evaluation of atmospheric-plasma-source absorption mode Fourier transform Orbitrap mass spectrometry for chlorinated paraffin mixtures

Chlorinated paraffins (CP) are complex molecular mixtures occurring in a wide range of isomers and homologs of environmental hazards, whose analytical complexity demand advanced mass spectrometry (MS) methods for their characterization. The reported formation of chlorinated olefins (COs) and other transformation products during CP biotransformation and degradation can alter the MS analysis, increasing the high resolution required to distinguish CPs from their degradation products. An advanced setup hyphenating a plasma ionization source and an external high-performance data acquisition and processing system to the legacy hybrid LTQ Orbitrap XL mass spectrometer is reported. First, the study demonstrated the versatility of a liquid sampling atmospheric pressure glow discharge, as a soft ionization technique, for CP analysis. Second, enhanced resolution and sensitivity provided by the absorption mode Fourier transform spectral representation on this legacy mass spectrometer are shown. The developed Orbitrap-based platform allowed the detection of new isotopic clusters and CPs and COs to be distinguished at medium resolution (setting 30,000 at m/z 400, ~ 400 ms transients), and even chlorinated di-olefins (CdiOs) at higher resolution (setting 100,000 at m/z 400, ~ 1500 ms transients). Overall, such proof-of-principle instrumental improvements are promising for environmental and analytical research in the field of CP analysis.Graphical

Electric Taxiing System. Kinetic Energy Recovery System as an Electric Taxiing Solution: Economic and environmental analysis: Phenom 300 case study

The aviation industry has thrived in recent years, with a significant increase in passenger numbers, leading to the development of larger aircraft fleets and the expansion of airport infrastructure. In 2019, more than 4.5 billion passengers traveled by airplane, which represents an 80% increase compared to 2009. As a consequence, this growth has also resulted in longer taxiing times for aircraft, increasing fuel consumption and operational costs. The industry's CO2 emissions have quadrupled since the 1960s, with over 1 billion tons released in 2019, contributing to global warming. Given that the improvements being made to current propulsion systems and the production of over 600 million liters of SAF (Sustainable Aviation Fuel) in 2023 do not seem sufficient to meet the ambitious goals set by regulators and operators, the logical solution would be to develop a system capable of moving the aircraft on the ground using alternative, cleaner, and cheaper energies, such as electric power. This paper explores the latest advancements in electric propulsion systems, specifically focusing on external and onboard systems. After the state of the art is established, this paper will cover a case study and propose a new alternative for an onboard system called ETS – Electric Taxiing System. The ETS is a 100% electric system for ground handling operations designed to use only the kinetic energy stored in a battery pack, which is recovered during aircraft landing and braking events. Although there are some studies on this topic, the author considers this paper to be more comprehensive as the results computed here take into account 96 variables, 60 simulations, several flight plans, and real-world data. The case study focuses on the implementation and dimensioning of the ETS, considering electric motor power and torque, and battery capacity for the Embraer Phenom 300. A brief economic and environmental analysis was also conducted, considering the operation of NetJets Europe, the world's leading and largest private jet company.

The green resource recovery process of a new type of selective bipolar membrane electrodialysis system for saline wastewater treatment

The selective electrodialysis with bipolar membrane (BMSED) is an advanced electro-membrane process that combines monovalent perm-selective ion exchange membrane and a bipolar membrane, and presented significant potential in high salinity wastewater treatment and reclamation. Herein, we accomplished an in-depth assessment of the external-integration and internal-integration systems for the treatment of high-salinity mining wastewater and seawater desalination concentrate brine. The issues surrounding their cycling performance during batch operation, their anti-fouling potential in the presence of Mg2+/Ca2+ ions, and its specific operational cost were thoroughly investigated. The results suggest that the internal integration system demonstrates suitable stability during long-term operation under batch (cycling) mode. Nevertheless, the membrane exhibited inorganic scaling due to co-ion leakage at high current density. A highly pure NaOH was obtained through an internal integration process at a cost of 0.68 $/kg, outperforming the external integration system (98.96 %, 1.85 $/kg). The findings presented in this study offer valuable insights for the industrial application of BMSED technology in managing high salinity wastewaters.

(Invited) Shunt-currents in Alkaline Water-Electrolyzers and Renewable Energy

Shunt-currents in bipolar cell stack design with a common electrolyte-feed and -outlet is an inevitable physical phenomenon governed by Ohms law that causes some extra challenges when alkaline water-electrolysers shall operate on renewable energy that is both dynamic and intermittent. Shunt-currents are also referred to as bypass-current or creep-current. The shunt-currents are to much degree governed by the electrolyte inside the cell stack manifold system that transports lye in and out of the cells. The electrolyte inside the manifold system also electrically connects the individual cells together and enables transport of ions/electricity in parallel to the cell stack. Thus, a small portion of the rectifier current is being shunted outside the cells and does not contribute to any production. Previous work on shunt-current modelling brought new insight on how to design the manifolds and raised the awareness on shunt-current and the use of metallic manifolds which both reduced the ohmic resistivity of the manifold system and was a source of secondary electrolysis.Classic alkaline water-electrolysers are typically using an internal manifold system where the inlet ports are located at the bottom of the cell stack and the outlet ports are located at the top, and where the ports connecting the cell-interior and the common manifold channel are short and straight. Such design has in the past worked satisfactory for alkaline water-electrolysers that have been working on a high nominal load and only being shut-down for maintenance a few times over the stack-lifetime, mainly causing a modest reduction in the current efficiency. Membrane-chlorine electrolysers on the other hand, are designed for very small shunt-currents by using an external manifold system, which enables a current protection system that protects electrodes from corrosion under shutdown conditions.Shunt-currents bypassing the cell stack does not contribute to any product and therefore constitutes a loss in current efficiency and, hence, an accordingly loss in the energy efficiency (the shunt-currents still adds to the electricity bill). The atmospheric alkaline electrolyser has a modest loss in current efficiency at nominal load where the high gas volume blocks much of the current path in the rather open outlet ports. The high-pressure alkaline electrolysers on the other hand, where the gas volumes are much smaller, the current efficiency can be as low as 89% at nominal load due to shunt-currents when using simple internal manifold system. For an electrolyser with already low current efficiency at the nominal load, the current efficiency will drop dramatically as the electrolyser is taken to lower load, severely compromising the energy efficiency. The impact on shunt-currents also dramatically increases for increased number of cells in a cell stack, and eventually limits the number of cells that can be assembled in one single cell stack operating on the same common lye system.Shutdown and discharge of the electrodes may further lead to corrosion and degradation of the electrodes, strongly influenced by the shunt-currents and the manifold system. Large cell stacks will discharge faster and deeper, eventually causing corrosion of the electrodes. As the cell stack is discharged the current in the cell stack is reversed where the hydrogen electrode is being polarized to anodic potentials, and the oxygen electrode is polarized to low cathodic potentials which eventually may challenging the material stability. Thus, evaluation of electrode potentials must be an integral part of development of industrial electrodes [LeRoy] and especially in intermittent operation where frequent shutdown will occur. A good integration of the manifold system into the cell stack can potentially mitigate both the loss of current efficiency under dynamic operation and the electrode corrosion under intermittent operation.

The PolyCraft Polymer–Metal Hybrid Smart Stent System: The Future of Cardiovascular Blood Pressure Management

AbstractTo address the complication of in‐stent restenosis that occurs with traditional stent treatments, this study proposes an innovative hybrid smart stent‐based medical system. This approach allows to overcome the limitations of existing bare metal or polymer‐based smart stents, which interfere with radio frequency signals, less deformability, or do not provide adequate radial support, respectively. The proposed hybrid stent, which uses a Co/Cr–polycaprolactone (PCL)–Co/Cr configuration connected by a unique dual inverted Y‐type connector for metal–polymer integration is integrated with a LC wireless pressure sensor fabricated through a semiconductor process. The fabricated hybrid stent made by laser machining and custom‐made 3D printing, offers excellent properties such as radial strength (0.125 N/mm) and flexibility (2 N mm2) and provides intravascular information to the outside through the integrated sensor without signal degradation. After basic experiments using a phantom, animal experiments are conducted by combining the fabricated sensor with artificial blood vessel, and the results measured by the external antenna system are consistent with the results of a commercial reference sensor. The proposed wireless sensor‐based smart stents and artificial blood vessels aim to gather diverse patient health data for integration with artificial intelligence, laying the groundwork for next‐generation medical innovation.

Development of a Porcine VCA Model Using an External Iliac Vessel-Based Vertical Rectus Abdominus Myocutaneous Flap.

Vascularized composite allotransplantation (VCA) involves transplanting a functional and anatomically complete tissue graft, such as a hand or face, from a deceased donor to a recipient. Although clinical VCA has resulted in successful outcomes, high rates of acute rejection and increased requirements for immunosuppression have led to significant long-term complications. Of note, immunosuppressed graft recipients are predisposed to infections, organ dysfunction, and malignancies. The long-term success of VCA grafts requires the discovery and implementation of unique approaches that avoid these complications altogether. Here, we describe our surgical technique and initial experience with a reproducible heterotopic porcine VCA model for the preclinical assessment of approaches to improve graft outcomes. Six heterotopic porcine allogeneic vertical rectus abdominis myocutaneous flap transplants were performed using Sinclair donors and Yucatan recipients. Immunosuppressive therapy was not used. Each flap was based on the left external iliac vessel system. Animals were followed postoperatively for surgery-related complications. The six pigs underwent successful VCA and were euthanized at the end of the study. Each flap demonstrated complete survival following vessel anastomosis. For the allogeneic recipients, on average, minimal erythema and healthy flap color were observed from postoperative days 1 to 4. There were no surgery-related animal deaths or complications. We have developed a reproducible, technically feasible heterotopic porcine VCA model based on the left external iliac vessel system. Our results demonstrate this model's potential to improve VCA graft outcomes by exploring tolerance induction and rejection biomarker discovery in preclinical studies.

ENHANCING DIGITAL TRANSACTIONS WITH BLOCKCHAIN TECHNOLOGY: DESCRIPTIVE-ANALYTICAL STUDY

Background: The emergence of Blockchain technology has led to profound transformations in digital transactions, offering a secure and transparent ledger for recording and processing transactions. This innovation holds promise for enhancing security, efficiency, and costeffectiveness across various sectors, including healthcare, education, finance, and real estate. Methods: This descriptive-analytical study explores the potential of Blockchain technology to revolutionise digital transactions. It employs a comprehensive review of existing literature and case studies to analyse the impact and applications of Blockchain across different domains. Results and conclusions: This research underscores the multifaceted benefits of Blockchain technology in streamlining processes, reducing transaction times, minimising fraud, and lowering costs across diverse industries. Blockchain emerges as a pioneering technology, functioning as the largest decentralised open database and facilitating transparent and secure data management. The technology, categorised into public, private, and hybrid types, comprises fundamental elements such as blocks, consensus mechanisms, cryptographic hash functions, and timestamps. With its core functions of transmission, storage, and automation, Blockchain disrupts conventional processes. Smart contracts, supported by external intermediaries like Oracle Programs, access data from external systems, enhancing their functionality and applicability. Moreover, Blockchain enables a departure from routine practices, ensuring robust monitoring of manufacturing processes, evaluating product quality, and verifying compliance with standards prior to market release.

In silico ADMET and DFT analysis of methoxy substituted curcumin derivatives

The current study aimed to predict drug ability of methoxy group substituted curcumin derivatives (MC1 to MC4) using ADMETLab 3.0 and DFT approaches. Almost all derivatives exhibited satisfactory physicochemical properties and medicinal chemistry. Pharmacokinetic profile revealed that all derivatives showed higher Caco-2 cell predicted permeability and exhibited a P-glycoprotein (Pgp) inhibitor capability, while non-of them is a Pgp-substrate. MC1 and MC2 exhibited favorable human intestinal absorption (HIA) values. MC1 was in favor of better oral bioavailability. Values for plasma protein binding and volume of distribution were optimum for MC1 and MC2. All compounds were unable to cross blood brain barrier. Fraction unbound in the plasma was moderate for all compounds. All derivatives exhibited moderate clearance rate, while having ultra short half-lives. Toxicity profile was moderate for almost all compounds. Similarly, the DFT computations of the compounds of the curcumin derivatives were conducted at B3LYP/6-311G** level to predict and then assess the key electronic characteristics underlying the bioactivity. Accordingly, the MC4 molecule (ΔEgap = 3.883 eV) would prefer to interact with the external molecular system more than the other molecules due to having the biggest energy gap. The ΔNmax (2.328 eV) and Δεback-donat. (−0.422 eV) scores implied that MC1 would have more charge transfer capability and the lowest stability via back donation among the compounds. In short, the derivative (MC1 to MC4) exhibited strong extrinsic therapeutic properties and therefore stand eligible for further in vitro and in vivo studies.

Ultra-low frequency noise external cavity diode laser systems for quantum applications

We present two distinct ultra-low frequency noise lasers at 729 nm with a fast frequency noise of 30 Hz2/Hz, corresponding to a Lorentzian linewidth of 0.1 kHz. The characteristics of both lasers, which are based on different types of laser diodes, are investigated using experimental and theoretical analysis with a focus on identifying the advantages and disadvantages of each type of system. Specifically, we study the differences and similarities in mode behavior while tuning frequency noise and linewidth reduction. Furthermore, we demonstrate the locking capability of these systems on medium-finesse cavities. The results provide insights into the unique operational characteristics of these ultra-low noise lasers and their potential applications in quantum technology that require high levels of control fidelity.

Narrow linewidth optical feedback vertical cavity surface emitting lasers based on cholesteric liquid crystal

Abstract In this paper, we present a narrow linewidth vertical cavity surface emitting laser (VCSEL) based on cholesteric liquid crystal (CLC). We investigated the impact of incorporating optical feedback into the external cavity on the linewidth of VCSELs, and successfully utilized CLC film as the reflector for the external cavity. This enabled us to achieve mode control and linewidth compression in VCSELs through optical feedback. The linewidth of the optically feedbacked VCSEL was measured at different driving currents and oxidation apertures. Under the same oxidation aperture, when the driving current is 1.2 mA, the linewidth is compressed from 120.9 MHz to 55.97 MHz; when the driving current is 0.8 mA, the linewidth is compressed from 22.87 MHz to 12.68 MHz. When the driving current remains constant, the linewidth is compressed from 169.31 MHz to 72 MHz when the oxidation aperture is 7 μm; and from 39.13 MHz to 10 MHz, when the oxidation aperture is 3 μm. By validating the feasibility of employing CLC film as an external cavity reflector mirror, our findings offer new insights towards achieving narrow-linewidth external cavity systems, thereby laying an experimental foundation for subsequent high-quality and highly integrated LC optical feedback VCSELs.

Relative-belief inference in quantum information theory

We introduce the framework of Bayesian relative belief that directly evaluates whether or not the experimental data at hand support a given hypothesis regarding a quantum system by directly comparing the prior and posterior probabilities for the hypothesis. In model-dimension certification tasks, we show that the relative-belief procedure typically chooses Hilbert spaces that are never smaller in dimension than those selected from optimizing a broad class of information criteria, including Akaike's criterion. As a concrete and focused exposition of this powerful evidence-based technique, we apply the relative-belief procedure to an important application: . In particular, just by comparing prior and posterior probabilities based on data, we demonstrate its capability of tracking multiphoton emissions using (realistically lossy) single-photon detectors in order to assess the actual quality of photon sources without making assumptions, thereby reliably safeguarding source integrity for general quantum-information and communication tasks with Bayesian reasoning. Finally, we discuss how relative belief can be exploited to carry out parametric model certification and estimate the total dimension of the quantum state for the combined (measured) physical and interacting external systems described by the Tavis-Cummings model. Published by the American Physical Society 2024

Reduced scale test bench for investigating the upward flame heat impact on external thermal insulation composite system facades

The project aimed to develop a reduced scale test protocol designed to be repeatable and capable of providing the upward fire evaluation for assessing fire risk on external thermal insulation composite system facade samples. The variation of heat flux is simulated by radiant panel. This experimental setup permits the recording of dynamic variables in flame propagation, such as ignition time, flame extinguishing time, and variations in both surface and back temperatures of the insulation panel. Notably, the measurement of back temperature provides a means to assess the thermal insulation efficiency of the external thermal insulation composite system facade. Furthermore, the fire spreading temperature is collected during the test could also be useful for larger-scale testing.

Adaptive sliding mode anti-swing control of 4-DOF tower crane based on a nonlinear disturbance observer

Tower cranes are widely applied in outdoor environments with inevitable external disturbances, which can reduce transportation efficiency and safety. To improve the transient control performance of the tower crane when transporting goods and to guarantee good robustness, this paper designs an adaptive sliding mode Anti-swing control method based on a nonlinear disturbance observer. Firstly, a 4-DOF tower crane error dynamics model considering external disturbances and air friction is established, and then, a nonlinear disturbance observer is designed to estimate the aggregate disturbance. Further, a disturbance effect indicator (DEI) is set to judge the advantages and disadvantages of the disturbance effect on the tower crane system from a new perspective. Finally, beneficial disturbance effects are organically combined with a sliding mode control method possessing an adaptive mechanism to eliminate payload swing by introducing favorable interference. Using Lyapunov stability analysis in conjunction with the LaSalle invariance principle, the closed-loop system is shown to be asymptotically stable. Simulation results show that the controller proposed in this paper achieves accurate positioning by driving the trolley and the jib, and at the same time, can keep the payload swing angle slight during the working process and eliminate the payload swing angle after accurate positioning. Moreover, it is also robust in the face of external disturbances and system parameter variations.