Contraction Dynamics Research Articles

Informal contracts' influence on shipping efficiency: a customer- perspective of package delivery agent

Understanding the role of informal agreements can help delivery services prioritize customer preferences, leading to improved service quality and customer satisfaction. Unfortunately, where there are gaps either on general understanding of communication stand in-between the different of failure and success. This qualitative research study delves into the dynamics of informal contracts between customers and package delivery agents, and their impact on the efficiency of the shipping process. The research aims to gain a deeper understanding of how these unwritten agreements affect various aspects of the delivery process from both the customer and delivery agent viewpoints. Through in-depth interviews and thematic analysis, this study sheds light on the nuances of these informal arrangements and their role in shaping the overall shipping experience. The study revealed that informal agreements play a significant role in package delivery experiences. Participants described unspoken arrangements formed through trust and effective communication. Adherence to these agreements positively influenced service efficiency, with prioritized deliveries and improved accuracy. However, deviations from agreements led to emotional reactions such as frustration and disappointment, impacting the perceived trustworthiness of the delivery service. Additionally, the study highlighted cultural variations in the adoption of informal agreements and the importance of clear communication in establishing and maintaining these arrangements.

Modeling the Impacts of Climate Change on Potential Distribution of Betula luminifera H. Winkler in China Using MaxEnt

Betula luminifera H. Winkler, a fast-growing broad-leaved tree species native to China’s subtropical regions, possesses significant ecological and economic value. The species’ adaptability and ornamental characteristics make it a crucial component of forest ecosystems. However, the impacts of global climate change on its geographical distribution are not well understood, necessitating research to predict its potential distribution shifts under future climate scenarios. Our aims were to forecast the impact of climate change on the potential suitable distribution of B. luminifera across China using the MaxEnt model, which is recognized for its high predictive accuracy and low sample data requirement. Geographical coordinate data of B. luminifera distribution points were collected from various databases and verified for redundancy. Nineteen bioclimatic variables were selected and screened for correlation to avoid overfitting in the model. The MaxEnt model was optimized using the ENMeval package, and the model accuracy was evaluated using the Akaike Information Criterion Correction (delta.AICc), Training Omission Rate (OR10), and Area Under the Curve (AUC). The potential distribution of B. luminifera was predicted under current and future climate scenarios based on the Shared Socio-economic Pathways (SSPs). The optimized MaxEnt model demonstrated high predictive accuracy with an AUC value of 0.9. The dominant environmental variables influencing the distribution of B. luminifera were annual precipitation, minimum temperature of the coldest month, and standard deviation of temperature seasonality. The potential suitable habitat area and its geographical location were predicted to change significantly under different future climate scenarios, with complex dynamics of habitat expansion and contraction. The distribution centroid of B. luminifera was also predicted to migrate, indicating a response to changing climatic conditions. Our findings underscore the importance of model optimization in enhancing predictive accuracy and provide valuable insights for the development of conservation strategies and forest management plans to address the challenges posed by climate change.

Precise Needle and Cannula Placement in the Forehead During Aesthetic Procedures: Can Device and Angulation Influence Accuracy? A Fresh Frozen Specimen Study.

Myomodulation is a technique aimed at enhancing the dynamics of muscle contraction and relaxation through methods like hyaluronic acid (HA) injection. Achieving optimal outcomes depends on the precise placement of the injected product within the targeted anatomical plane. This is particularly important in the forehead, an area with elevated vascular risk. The selected treatment techniques must ensure both efficacy and safety. This study aims to assess the anatomical precision of HA injections in the forehead using different techniques and devices. Four fresh frozen specimens were injected with HA by five experienced board-certified plastic surgeons using three different techniques/devices: (1) a 50mm, 22G microcannula; (2) a 13mm, 27G needle with the bevel down at a 45-degree angle; and (3) the same needle positioned at a 90-degree angle. Ultrasound analysis was used to evaluate the precision of each approach. Both the cannula technique and the needle technique with the bevel down at a 45-degree angle consistently delivered the filler to the supraperiosteal layer in 100% of cases without spreading. However, the 90-degree needle technique, despite correct placement on the periosteum, resulted in filler dispersion across multiple layers. The accuracy of filler placement in the forehead is influenced by the choice of device and its angulation. It is recommended to use a cannula with the entry point at the frontalis crest or a needle angled at 45 degrees to the skin. The use of a needle at a 90-degree angle should be avoided to ensure precise placement and avoid filler migration. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Mechanical boundary conditions for motor protein dictate geometric pattern and dynamics of actin gel contraction

Mechanical boundary conditions for motor protein dictate geometric pattern and dynamics of actin gel contraction

Adapting and optimizing GCaMP8f for use in Caenorhabditis elegans.

Improved genetically encoded calcium indicators (GECIs) are essential for capturing intracellular dynamics of both muscle and neurons. A novel set of GECIs with ultrafast kinetics and high sensitivity was recently reported by Zhang et al. (2023). While these indicators, called jGCaMP8, were demonstrated to work in Drosophila and mice, data for Caenorhabditis elegans were not reported. Here, we present an optimized construct for C. elegans and use this to generate several strains expressing GCaMP8f (fast variant of the indicator). Utilizing the myo-2 promoter, we compare pharyngeal muscle activity measured with GCaMP7f and GCaMP8f and find that GCaMP8f is brighter upon binding to calcium, shows faster kinetics, and is not disruptive to the intrinsic contraction dynamics of the pharynx. Additionally, we validate its application for detecting neuronal activity in touch receptor neurons which reveals robust calcium transients even at small stimulus amplitudes. As such, we establish GCaMP8f as a potent tool for C. elegans research which is capable of extracting fast calcium dynamics at very low magnifications across multiple cell types.

P-198 Time to maximum blastocyst expansion (tmBE) may represent a novel metric for assessing embryo competence

Abstract Study question Can the time to achieve maximum blastocyst expansion (tmBE) and the frequency of spontaneous collapses serve as useful indicators of embryo competence? Summary answer Compared to the frequency of spontaneous collapses, tmBE was a better indicator of embryo competence, potentially serving as a valuable metric for embryo selection. What is known already Identifying the most viable blastocyst for transfer is essential for success in assisted reproduction. In scenarios with good prognosis, such as oocyte donation, blastocyst selection may require a more nuanced approach, given the high number of available good quality embryos. Exploring indicators of embryo competence beyond traditional morphology-based criteria may be beneficial, however an in-depth understanding is still lacking. Blastocyst expansion and contraction dynamics have been suggested to play a role in developmental and chromosomal fitness. However, their predictive value has not been investigated across a wide range of patient populations. Study design, size, duration This is a single-center retrospective study of 287 blastocysts transferred in autologous (n = 88) and heterologous (n = 199) cycles, performed between September 2019 and September 2022. Only fresh single embryo transfers were considered. We compared blastocysts across two groups: advanced maternal age (AMA) patients (>35 years old, n = 88) and oocyte donors (<35 years old, n = 199). We evaluated well-established indicators of embryo quality, as well as novel metrics, including tmBE and the frequency of spontaneous collapses. Participants/materials, setting, methods Conventional indicators of embryo quality included blastocyst grade and morphokinetic timings (tPNf, t2, t3, t4, t5, t8, tSB and tB). tMBE was defined as the maximum time (hpi) required for the blastocyst to reach its largest diameter, extending beyond tB. Blastocyst contractions were measured as a decrease and subsequent recovery of the blastocoel area over time. ImageJ was employed for size measurements. p<0.05 was considered statistically significant after Two-tailed Student’s t-test or Chi-square test. Main results and the role of chance We observed a significant difference in live birth rates between oocyte donors and AMA patients (40% vs 18%, p=0.0004). Nevertheless, there were no differences across blastocyst expansion scores between oocyte donors and AMA patients (5= 58% vs 65%; 4= 38% vs 30% and 3= 4% vs 5%, p > 0.05), nor in their morphology score (Excellent= 57% vs 61%; Good= 24% vs 18%; Average= 15% vs 16% and Poor= 4% vs 5%). In terms of morphokinetics, when comparing oocyte donor and AMA embryos, the only significant difference was observed at tPNF (22.0±2.4 vs 22.6±2.3; p= 0.04). No differences were found at t2, t3, t4, t5, t8, tSB and tB. Additionally, the frequency of spontaneous collapses showed no significant differences between the oocyte donor and AMA group (1.4±1.2 vs 1.5±1.0, p=0.66). However, blastocysts from oocyte donors reached tmBE significantly faster than AMA embryos (115.0±4.8 vs 117.2±3.4; p = 0.0003). When these variables were further correlated to clinical outcomes, the frequency of spontaneous collapses did not appear to influence live birth in either group. Notably, however, tmBE was significantly shorter for embryos resulting in a live birth, across both the oocyte donor (113.5 vs 115.4, p = 0.04) and AMA group (115.6 vs 117.6, p = 0.04). Limitations, reasons for caution This is a single center retrospective study with a relatively small sample size, especially in the AMA group. Caution should be made when generalizing results to other patient populations, as confounding were not taken into consideration. No data on the chromosomal status of embryos was available. Wider implications of the findings Our results suggest that tMBE may serve as a reliable indicator of embryo potential, allowing a more nuanced embryo selection, particularly in cases with a high number of good quality embryos. This study opens avenues for further research into novel metrics for assessing embryo competence Trial registration number not applicable

Modeling normal mouse uterine contraction and placental perfusion with non-invasive longitudinal dynamic contrast enhancement MRI.

The placenta is a transient organ critical for fetal development. Disruptions of normal placental functions can impact health throughout an individual's entire life. Although being recognized by the NIH Human Placenta Project as an important organ, the placenta remains understudied, partly because of a lack of non-invasive tools for longitudinally evaluation for key aspects of placental functionalities. Our goal is to create a non-invasive preclinical imaging pipeline that can longitudinally probe murine placental health in vivo. We use advanced imaging processing schemes to establish functional biomarkers for non-invasive longitudinal evaluation of placental development. We implement dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) and analysis pipeline to quantify uterine contraction and placental perfusion dynamics. We use optic flow and time-frequency analysis to quantify and characterize contraction-related placental motion. Our novel imaging and analysis pipeline uses subcutaneous administration of gadolinium for steepest slope-based perfusion evaluation, enabling non-invasive longitudinal monitoring. We demonstrate that the placenta exhibits spatially asymmetric contractile motion that develops from E14.5 to E17.5. Additionally, we see that placental perfusion, perfusion delivery rate, and substrate delivery all increase from E14.5 to E17.5, with the High Perfusion Chamber (HPC) leading the placental changes that occur from E14.5 to E17.5. We advance the placental perfusion chamber paradigm with a novel, physiologically based threshold model for chamber localization and demonstrate spatially varying placental chambers using multiple functional metrics that assess mouse placental development and remodeling throughout gestation. Our pipeline enables the non-invasive, longitudinal assessment of multiple placenta functions from a single imaging session. Our pipeline serves as a key toolbox for advancing research in mouse models of placental disease and disorder.

Compliant control of biomimetic parallel torso based on musculoskeletal control

Compliant movement and stress buffering of the torso are particularly important for state transition during high-speed locomotion in quadrupedal mammals. Currently, passive compliant control is commonly used in bionic torsos of quadruped robots, while active compliant control remains rare and immature. In previous research, we developed an active six-Degree-of-Freedom (DoF) bionic parallel torso. In this paper, we establish a muscle model that includes four biomechanical elements representing muscle characteristics (muscle force-fiber length and muscle velocity relationships) from the perspective of biology and physiology. We propose a musculoskeletal model that simulates the biological motion control system to control the compliant movement of each joint of the parallel mechanism. This model includes: 1) a neural equilibrium point controller that represents the transmission of motion commands, 2) activation dynamics that describe the activation of stimulated muscles, 3) contraction dynamics that emphasize the biomechanical characteristics of muscle tendons, 4) skeletal dynamics that describe bone movement. The effects of flexor and extensor stimulation on muscle activation, force, length, and velocity were analyzed. The results showed that both the flexor and extensor muscles will contract after corresponding stimulation. Furthermore, adjusting muscle stimulation through the musculoskeletal model can drive the parallel mechanism to reach the desired position. The musculoskeletal control method based on external force feedback can establish new torque balance in joints and drive the parallel torso to achieve compliant movements. Simulation and experiments have demonstrated the feasibility of the musculoskeletal control method. This method enhances the compliance and environmental adaptability of the parallel torso in practical applications.

Myosin light chain phosphatase is a downstream target of Rho-kinase in endothelin-1-induced transactivation of the TGF-β receptor.

Rho-kinase (ROCK) regulates actomyosin contraction, coronary vasospasm, and cytoskeleton dynamics. ROCK and of NADPH oxidase (NOX) play an essential role in cardiovascular disease and proteoglycan synthesis, which promotes atherosclerosis by trapping low density lipoprotein. ROCK is activated by endothelin-1 (ET1) and transactivates the transforming growth factor beta receptor (TGFβR1), intensifying Smad signaling and proteoglycan production. This study aimed to identify the role of myosin light chain phosphatase (MLCP) as a downstream target of ROCK in TβR1 transactivation. Vascular smooth muscle cells were treated with ET1 and inhibitors of ROCK and MLCP were added. The phosphorylation levels of Smad2C, myosin light chain (MLC), and MLCP were monitored by western blot, and the mRNA expression of chondroitin 4-O-sulfotransferase 1 (C4ST1) was assessed by quantitative real-time PCR. We examined ROCK's role in ET1-induced TGFβR1 activation. ROCK phosphorylated MLCP at the MYPT1 T853 residue, blocked by the ROCK inhibitor Y27632. ROCK also increased MLC phosphorylation and actomyosin contraction in response to ET1, enhanced by the phosphatase inhibitor Calyculin A. Calyculin A also increased C4ST1 expression, GAG-chain synthesizing enzymes. This work suggests that ROCK is involved in ET1-mediated TβR1 activation through increased MLCP phosphorylation, which leads to Smad2C phosphorylation and stimulates C4ST1 expression.

Fluid dynamics and leukocyte transit in the lymphatic system.

The lymphatic system plays a vital role in maintaining fluid balance in living tissue and serves as a pathway for the transport of antigen, immune cells, and metastatic cancer cells. In this study, we investigate how the movement of cells through a contracting lymphatic vessel differs from steady flow, using a lattice Boltzmann-based computational model. Our model consists of cells carried by flow in a 2D vessel with regularly spaced, bi-leaflet valves that ensure net downstream flow as the vessel walls contract autonomously in response to calcium and nitric oxide levels regulated by stretch and shear stress levels. The orientation of the vessel with respect to gravity, which may oppose or assist fluid flow, significantly modulates cellular motion due to its effect on the contraction dynamics of the vessel, even when the cells themselves are neutrally buoyant. Additionally, our model shows that cells are carried along with the flow, but when the vessel is actively contracting, they move faster than the average fluid velocity. We also find that the fluid forces cause significant deformation of the compliant cells, especially in the vicinity of the valves. Our study highlights the importance of considering the complex, transient flows near the valves in understanding cellular motion in lymphatic vessels.

Imaging the dynamics of murine uterine contractions in early pregnancy†.

Uterine muscle contractility is essential for reproductive processes including sperm and embryo transport, and during the uterine cycle to remove menstrual effluent. Even still, uterine contractions have primarily been studied in the context of preterm labor. This is partly due to a lack of methods for studying the uterine muscle contractility in the intact organ. Here, we describe an imaging-based method to evaluate mouse uterine contractility of both the longitudinal and circular muscles in the cycling stages and in early pregnancy. By transforming the image-based data into three-dimensional spatiotemporal contractility maps, we calculate waveform characteristics of muscle contractions, including amplitude, frequency, wavelength, and velocity. We report that the native organ is highly contractile during the progesterone-dominant diestrus stage of the cycle when compared to the estrogen-dominant proestrus and estrus stages. We also observed that during the first phase of uterine embryo movement when clustered embryos move toward the middle of the uterine horn, contractions are dynamic and non-uniform between different segments of the uterine horn. In the second phase of embryo movement, contractions are more uniform and rhythmic throughout the uterine horn. Finally, in Lpar3-/- uteri, which display faster embryo movement, we observe global and regional increases in contractility. Our method provides a means to understand the wave characteristics of uterine smooth muscle in response to modulators and in genetic mutants. Better understanding uterine contractility in the early pregnancy stages is critical for the advancement of artificial reproductive technologies and a possibility of modulating embryo movement during clinical embryo transfers.

Psychological Contract: A Systematic Literature Review

English abstract only consisted of one paragraph This comprehensive study thoroughly examines the psychological contract literature by reviewing 134 papers published from 1989 to 2022. It extensively explores various aspects, including the conceptual framework, classifications, influencing factors, measurement criteria, and evolutionary trends of psychological contracts. Through a critical analysis, this paper reveals that certain areas within the realm of psychological contracts have reached a saturation point, with a wealth of existing research. It highlights the need for a paradigm shift towards studies conducted from the employer's standpoint, which can offer invaluable insights into the dynamics of psychological contracts. In essence, this review encapsulates the existing knowledge on psychological contracts and maps out a roadmap for future research, emphasizing the importance of diverse perspectives and methodological approaches

Enhancing and Decoding the Performance of Muscle Actuators with Flexures

Leveraging living muscle as an efficient and adaptive actuator for soft robots has been of increasing interest over the past decade, with a focus on proof‐of‐concept demonstrations of function. Reproducible design and scalable manufacturing of biohybrid machines requires methods to increase the stroke output of strain‐limited muscle actuators and enable accurate and precise quality control and performance monitoring. Compliant mechanical elements, termed flexures, are designed to enhance muscle contractile stroke to ≈5× previously reported values and decode contraction dynamics with high spatiotemporal resolution. Combining rigid and flexible elements within a linear elastic flexure enables us to outperform the sensitivity of gold standard elastomeric beam‐based measurements of muscle contraction at both low‐ and high‐frequency stimulations. Flexures are leveraged to make quantitative comparisons of force, work, and power outputs in muscle actuators, driving us to discover a new observation of frequency‐dependent fatigue in muscle, and also develop a novel method for tuning muscle contractile dynamics in a frequency‐independent manner. By enhancing the contractile stroke of muscle actuators and precisely tuning contractile dynamics and endurance with unprecedented precision, this study sets the stage for leveraging flexures to improve robust, reproducible, and predictive design and manufacturing of next‐generation biohybrid robots.

The Turkish Constitutional Court and Turkey’s Democratic Breakdown: Judicial Politics Under Pressure

Abstract Under Turkey’s democratic breakdown, the Turkish Constitutional Court offers a case study to identify the dynamics of judicial politics in electoral autocracies. Although the Court has been subject to criticism regarding its low commitment to the political pluralism and rights-based approach previously, the current situation presents itself differently. It is marked by a massive erosion in democratic qualities including an abuse of the judiciary against dissents in an unprecedented manner. Yet, the Court is still formally independent and empowered through constitutional norms such as the fixed tenure, retirement age, and jurisdiction in crucial matters. Since the institutional guarantees of the Constitutional Court are untouched, it has still the potential to become a major political player. Therefore, its study may also contribute to the comparative scholarship on the role of constitutional review under new pressures of the third wave autocratization that contraction and expansion dynamics of judiciaries can be better understood. The present study aims to feature the judicial politics of the Court under Turkey’s current democratic regression by conceptualizing a resistance-deference paradox on the ground politically significant cases.

Psychological Contract, Organizational Commitment and Relational Performance of College Teachers in Guangxi, China

This study aims to provide an in-depth study of the complex dynamics of psychological contracts among teachers at several different types of universities in the Guangxi region of China and their impact on improving relationship performance. Data were collected from teachers in comprehensive universities and vocational colleges through questionnaires. The study found that teachers' evaluation of psychological contract is closely related to their organizational commitment and relationship performance, among which organizational commitment plays a mediating role between psychological contract and relationship performance. There are certain differences in psychological contract, organizational commitment and relationship performance among different types of university teachers, but overall, they show a consistent trend. Based on the research results, a series of suggestions are put forward to promote the improvement of teacher relationship performance, with a view to providing reference for educational management and practice.

The effect of C60 fullerenes on the recovery of muscle soleus contraction dynamics in rats after chronic alcoholization

Background. It has been shown that the available therapeutic agents do not eliminate the consequences of miotic pathologies in chronic alcoholism, the most significant of which are disturbances in the dynamics of muscle contraction. A positive effect of biocompatible water-soluble C60 fullerenes on the contraction parameters of damaged muscles has been established. In addition, administration of C60 fullerene aqueous solution during chronic alcoholization of rats protects muscle tissue from damage caused by oxidative stress. Materials and Methods. Biomechanical parameters such as the values of the minimum and maximum contraction force and the muscle force impulse were evaluated using tensometry. The blood levels of creatine phosphokinase and lactate dehydrogenase, creatinine and lactate as well as the level of oxidative processes in muscle tissue of experimental animals (content of hydrogen peroxide, activity of catalase, glutathione peroxidase and superoxide dismutase) as markers of muscle damage were determined using methods of biochemical analysis. Results. The C60 fullerene aqueous solution effect on the skeletal muscle contraction dynamics in rats after chronic alcoholization for 9 months and cessation of alcohol consumption for 1 month was investigated. It was established that water-soluble C60 fullerenes (daily dose of 1 mg/kg) reduce the effects of chronic alcoholization by 35–40±2 % on the studied biomechanical parameters and by 20±1 % on the studied biochemical parameters compared to the group of alcoholized animals, thus increasing the energy capabilities of the muscular system. Conclusions. The obtained data indicate a pronounced protective effect of C60 fullerenes on the muscle soleus contraction dynamics during the development of alcoholic myopathy, which opens up the potential possibility of their use for the prevention and correction of miotic damage.

A novel technique to quantify the kinetics of blood clot contraction based on the expulsion of fluorescently labeled albumin into serum

BackgroundThe platelet-driven contraction or retraction of blood clots has been utilized to obtain blood serum for laboratory studies, but now, in vitro clot contraction assays are used in research laboratories and clinics to assess platelet functionality. The static final extent of clot contraction measured using a clot size or expelled serum volume can be supplemented substantially with a dynamic analysis. ObjectivesTo provide a step-by-step protocol for a relatively simple and affordable new automated methodology to follow the kinetics of blood clot contraction, which allows for simultaneous measurements of various samples at a time and requires only a fluorescence plate reader. MethodsThe kinetics of clot contraction in whole blood was assessed by continuously detecting the fluorescence intensity of fluorescein isothiocyanate-albumin added to a blood sample before clotting and expelled into the serum during clot shrinkage. ResultsThe clots are formed and fluorescence is measured in the wells of a black multiwell plate using a standard plate fluorescent reader. The specificity of this technique for clot contraction has been demonstrated by the strong inhibitory effects of blebbistatin, latrunculin A, and abciximab. To validate the new technique, increased fluorescence intensity in the contracting clots was measured in parallel with a visual decrease in clot size performed with the same blood samples. ConclusionThe resulting clot contraction dynamics based on the expulsion of fluorescein isothiocyanate-albumin can be quantified using a number of kinetic parameters as well as a phase kinetics analysis. The advantages and drawbacks of the new technique are discussed.

Comparative Pangenomic Insights into the Distinct Evolution of Virulence Factors Among Grapevine Trunk Pathogens.

The permanent organs of grapevines (Vitis vinifera L.), like those of other woody perennials, are colonized by various unrelated pathogenic ascomycete fungi secreting cell wall-degrading enzymes and phytotoxic secondary metabolites that contribute to host damage and disease symptoms. Trunk pathogens differ in the symptoms they induce and the extent and speed of damage. Isolates of the same species often display a wide virulence range, even within the same vineyard. This study focuses on Eutypa lata, Neofusicoccum parvum, and Phaeoacremonium minimum, causal agents of Eutypa dieback, Botryosphaeria dieback, and Esca, respectively. We sequenced 50 isolates from viticulture regions worldwide and built nucleotide-level, reference-free pangenomes for each species. Through examination of genomic diversity and pangenome structure, we analyzed intraspecific conservation and variability of putative virulence factors, focusing on functions under positive selection and recent gene family dynamics of contraction and expansion. Our findings reveal contrasting distributions of putative virulence factors in the core, dispensable, and private genomes of each pangenome. For example, carbohydrate active enzymes (CAZymes) were prevalent in the core genomes of each pangenome, whereas biosynthetic gene clusters were prevalent in the dispensable genomes of E. lata and P. minimum. The dispensable fractions were also enriched in Gypsy transposable elements and virulence factors under positive selection (polyketide synthase genes in E. lata and P. minimum, glycosyltransferases in N. parvum). Our findings underscore the complexity of the genomic architecture in each species and provide insights into their adaptive strategies, enhancing our understanding of the underlying mechanisms of virulence. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

The Contents of Indonesian Muslim Academics’ Psychological Contract

This case study describes the dynamics of psychological contracts within the academic environment, with a focused examination on the experiences of academics at the University of Darussalam Gontor. Eight distinct psychological contracts emerge, encompassing appropriate compensation, fair distribution of workload, flexible working hours, attention from the university, organisational support, clear systems and rules, quick movement, and good culture. Each represents a unique set of expectations and obligations. Additionally, the study sheds light on the development of these contracts, highlighting how prior experiences, interactions within the university, institutional policies, and organizational culture collectively shape and influence academics’ perceptions of their roles and responsibilities. The findings provide invaluable insights into the nuanced interplay between individual expectations and institutional obligations, offering a deeper understanding of the factors that underpin a thriving academic community. Moreover, this study serves as a foundation for fostering an environment that supports the holistic development of both academics and the institution.

Optimal fibre length and maximum isometric force are the most influential parameters when modelling muscular adaptations to unloading using Hill-type muscle models.

Introduction: Spaceflight is associated with severe muscular adaptations with substantial inter-individual variability. A Hill-type muscle model is a common method to replicate muscle physiology in musculoskeletal simulations, but little is known about how the underlying parameters should be adjusted to model adaptations to unloading. The aim of this study was to determine how Hill-type muscle model parameters should be adjusted to model disuse muscular adaptations. Methods: Isokinetic dynamometer data were taken from a bed rest campaign and used to perform tracking simulations at two knee extension angular velocities (30°·s-1 and 180°·s-1). The activation and contraction dynamics were solved using an optimal control approach and direct collocation method. A Monte Carlo sampling technique was used to perturb muscle model parameters within physiological boundaries to create a range of theoretical and feasible parameters to model muscle adaptations. Results: Optimal fibre length could not be shortened by more than 67% and 61% for the knee flexors and non-knee muscles, respectively. Discussion: The Hill-type muscle model successfully replicated muscular adaptations due to unloading, and recreated salient features of muscle behaviour associated with spaceflight, such as altered force-length behaviour. Future researchers should carefully adjust the optimal fibre lengths of their muscle-models when trying to model adaptations to unloading, particularly muscles that primarily operate on the ascending and descending limbs of the force-length relationship.