Cycle Position Research Articles

Enhancing model identification with SINDy via nullcline reconstruction.

Many dynamical systems exhibit oscillatory behavior that can be modeled with differential equations. Recently, these equations have increasingly been derived through data-driven methods, including the transparent technique known as Sparse Identification of Nonlinear Dynamics (SINDy). This paper illustrates the importance of accurately determining the system's limit cycle position in phase space for identifying sparse and effective models. We introduce a method for identifying the limit cycle position and the system's nullclines by applying SINDy to datasets adjusted with various offsets. This approach is evaluated using three criteria: model complexity, coefficient of determination, and generalization error. We applied this method to several models: the oscillatory FitzHugh-Nagumo model, a more complex model consisting of two coupled cubic differential equations with a single stable state, and a multistable model of glycolytic oscillations. Our results confirm that incorporating detailed information about the limit cycle in phase space enhances the accuracy of model identification in oscillatory systems.

Konsep Daur Belajar sebagai Implementasi Manajemen Kurikulum di Sanggar Anak Alam Yogyakarta

This research aims to describe the learning cycle concept as an implementation of curriculum management at Sanggar Anak Alam (SALAM) Yogyakarta. Indonesia's curriculum policy nomenclature changes from year to year, however, Sanggar Anak Alam (SALAM) itself consistently carries out learning cycle-based curriculum practices as a form of research. This curriculum practice has been running since the inception of SALAM in 1988 until now. Researchers use a case study approach with a qualitative type of research. Data was obtained through interviews, observation and documentation. The data is then analyzed using condensation techniques, presenting the data until conclusions are drawn. The results of the research include first, SALAM holistic education is carried out through a learning cycle and is supported by activities such as the Monday Legi market and minitrip. Second, learning cycle-based curriculum management practices with curriculum planning, implementation and evaluation. Curriculum management through the learning cycle positions students as real subjects, choosing to carry out and achieve goals with the help of facilitators so that holistic education is achieved.

A low-cost open-source imaging platform reveals spatiotemporal insight into leaf elongation and movement.

Plant organs move throughout the diurnal cycle, changing leaf and petiole positions to balance light capture, leaf temperature, and water loss under dynamic environmental conditions. Upward movement of the petiole, called hyponasty, is one of several traits of the shade avoidance syndrome (SAS). SAS traits are elicited upon perception of vegetation shade signals such as far-red light (FR) and improve light capture in dense vegetation. Monitoring plant movement at a high temporal resolution allows studying functionality and molecular regulation of hyponasty. However, high temporal resolution imaging solutions are often very expensive, making this unavailable to many researchers. Here, we present a modular and low-cost imaging set-up, based on small Raspberry Pi computers, that can track leaf movements and elongation growth with high temporal resolution. We also developed an open-source, semi-automated image analysis pipeline. Using this setup we followed responses to FR enrichment, light intensity, and their interactions. Tracking both elongation and the angle of the petiole, lamina, and entire leaf in Arabidopsis (Arabidopsis thaliana) revealed insight into R:FR sensitivities of leaf growth and movement dynamics and the interactions of R:FR with background light intensity. The detailed imaging options of this system allowed us to identify spatially separate bending points for petiole and lamina positioning of the leaf.

The life cycle and competitive position of tourism destinations: a global empirical approach

ABSTRACT The competitiveness of tourism destinations depends on their degree of development or maturity. This article uses cluster analysis methods to establish the position in the life cycle of destinations in a pool of 154 countries. The article also explores their evolution between 2007 and 2017 doing a static comparative exercise. The position in the life cycle is determined by using confidence intervals for the means of the main variables. Following a recent and innovative methodology, thresholds are proposed that could potentially allow for a change of phase in the life cycle. Moreover, the article examines the main determinants of the competitiveness of the different destination groups as a function of their life-cycle position.

CCRG-01. INFERENCE OF CELL CYCLE REGULATION BETWEEN GLIOBLASTOMA SUBPOPULATIONS IN VIVO TO DRIVE COMPUTATIONAL AND MATHEMATICAL MODELS OF THE CANCER COMPLEX SYSTEM

Abstract Glioblastoma (GBM) is the most aggressive and most common primary malignant brain tumor in adults, with a poor median survival time of 15 months. One of the key challenges in treating GBM is its highly heterogeneous nature, with multiple distinct subtypes that have been shown to occur on both inter- and intra-patient levels. Three main classifications, known as classical/proliferative, mesenchymal and proneural have become commonly demonstrated phenotypes. The cell cycle is a fundamental and highly conserved process that controls faithful division of cells; dysregulation of the cell cycle is known to be a key driver in many cancers. However, how the cell cycle is differently regulated between these subtypes has not been well classified in vivo. We investigate these three GBM subtypes using a recently published single nucleus RNAseq (snRNAseq) data set. We compare cell cycle regulation/dysregulation among these three subtypes using Tricycle, an R/Bioconductor package that utilises dimension reduction via principal component analysis and transfer learning to infer cell cycle position from any snRNAseq data set. We find that the classical GBM subtype has the highest proportion of actively dividing cells (cells in: S/G2/M phases), while the mesenchymal and proneural subtypes have a very low proportion of actively dividing cells. This supports the idea of a proliferation-migration dichotomy between GBM subtypes. We use this proportion of actively proliferating cells to calibrate a minimal spatiotemporal mathematical model for GBM tumor growth that accounts for the differences in cell cycle regulation between these three GBM subtypes.

Microfluidic single-cell measurements of oxidative stress as a function of cell cycle position.

Single-cell measurements routinely demonstrate high levels of variation between cells, but fewer studies provide insight into the analytical and biological sources of this variation. This is particularly true of chemical cytometry, in which individual cells are lysed and their contents separated, compared to more established single-cell measurements of the genome and transcriptome. To characterize population-level variation and its sources, we analyzed oxidative stress levels in 1278 individual Dictyostelium discoideum cells as a function of exogenous stress level and cell cycle position. Cells were exposed to varying levels of oxidative stress via singlet oxygen generation using the photosensitizer Rose Bengal. Single-cell data reproduced the dose-response observed in ensemble measurements by CE-LIF, superimposed with high levels of heterogeneity. Through experiments and data analysis, we explored possible biological sources of this heterogeneity. No trend was observed between population variation and oxidative stress level, but cell cycle position was a major contributor to heterogeneity in oxidative stress. Cells synchronized to the same stage of cell division were less heterogeneous than unsynchronized cells (RSD of 37-51% vs 93%), and mitotic cells had higher levels of reactive oxygen species than interphase cells. While past research has proposed changes in cell size during the cell cycle as a source of biological noise, the measurements presented here use an internal standard to normalize for effects of cell volume, suggesting a more complex contribution of cell cycle to heterogeneity of oxidative stress.

A novel method of determining the active drag profile in swimming via data manipulation of multiple tension force collection methods

A novel method aimed at evaluating the active drag profile during front-crawl swimming is proposed. Fourteen full trials were conducted with each trial using a stationary load cell set-up and a commercial resistance trainer to record the tension force in a rope, caused by an athlete swimming. Seven different stroke cycles in each experiment were identified for resampling time dependent data into position dependent data. Active drag was then calculated by subtracting resistance trainer force data away from the stationary load cell force data. Mean active drag values across the stroke cycle were calculated for comparison with existing methods, with mean active drag values calculated between 76 and 140 N depending on the trial. Comparing results with established active drag methods, such as the Velocity Perturbation Method (VPM), shows agreement in the magnitude of the mean active drag forces. Repeatability was investigated using one athlete, repeating the load cell set-up experiment, indicating results collected could range by 88 N depending on stroke cycle position. Variation in results is likely due to inconsistencies in swimmer technique and power output, although further investigation is required. The method outlined is proposed as a representation of the active drag profile over a full stroke cycle.

Discrete electrocardiogram T amplitude detection based on cycle duration

In each cycle of the electrocardiogram wave there are P, Q, R, S and T amplitudes. Many studies have been conducted to obtain amplitude and QRS waves because they are related to ventricular depolarization, but to obtain T amplitude values related to ventricular repolarization are still rarely done, not even for the clinical standard (12 leads). This study aims to obtain the amplitude T value in each cycle and each electrocardiogram lead. Obtaining the amplitude T position on the reference lead will also find the amplitude T value on the other lead. Each cycle duration obtained from the duration RN to RN+1 is used to obtain the position of the endpoint of each cycle. The maximum value between the amplitude S position and the end point of the cycle is the amplitude T value. The results of research on 10 Physionet sinus rhythm samples and 10 Saiful Anwar Hospital Malang samples show that the duration of the cycle was successful in obtaining the amplitude T value for each lead. All samples can display a value. The amplitude in each cycle, where the values obtained in each cycle are still in normal conditions. The amplitude T value obtained is certainly accurate because there is only one positive value between the amplitude S position and the end of the cycle position. The position of the amplitude integer T found in a cycle in one lead will be the same as the position of the amplitude integer T in the cycle for the other lead. This occurs because of the simultaneous transmission of impulses that affect the atrial and ventricular muscle cells. The position of the amplitude T for each cycle can be found by filtering the maximum amplitude value between the amplitude position S and the final position of the cycle. Practically, this method can be programmed to be added to a digital electrocardiograph

Revisiting the cycle-rotation connection for late-type stars

Aims. We analyse the relation between the activity cycle length and the Rossby number, which serves as a ‘normalised’ rotation period and appears to be the natural parameter in any cycle relation. Methods. We collected a sample of 44 main sequence stars with well-known activity cycle periods and rotation periods. To compute the Rossby numbers from the observed rotation periods, we used the respective B − V-dependent empirical turnover-times and derived the empirical relation between the cycle length and Rossby number. Results. We found a linear behaviour in the double-logarithmic relation between the Rossby number and cycle period. The bifurcation into a long and a short period branch is clearly real but it depends, empirically, on the colour index B − V, indicating a physical dependence on effective temperature and position on the main sequence. Furthermore, there is also a correlation between cycle length and convective turnover time with the relative depth of the convection zone. Based on this, we derived empirical relations between cycle period and Rossby number individually for narrow B − V ranges, for both cycle branches, as well as a global relation for the short-period branch. For the short period cycle branch relations, we estimated a scatter of the relative deviation between 14% and 28% on the long-period cycle branch. With these relations derived purely from stellar data, we obtained a good match with the 10.3−1.0+1.1 yr period for the well known 11-year solar Schwabe cycle and a long-period branch value of 104−34+50 yr for the Gleissberg cycle of the Sun. Finally, we suggest that the cycles on the short-period branch appear to be generated in the deeper layers of the convective zone, while long-period branch cycles seem to be related to fewer deep layers in that zone. Conclusions. We show that for a broader B − V range, the Rossby number is a more suitable parameter for universal relation with cycle-rotation than just the rotation period alone. As proof, we demonstrate that our empirical stellar relations are consistent with the 11-year solar Schwabe cycle, in contrast to earlier studies using just the rotation period in their relations. Previous studies have tried to explain the cycle position of the Sun in the cycle-rotation presentation via other kinds of dynamo, however, in our study, no evidence is found that would suggest another type of dynamo for the Sun and other stars.

Evaluation of the NDVI Index as a Source of Information on Aboveground Phytomass in Steppes

The complexity of phytomass measurements on sample plots hinders the extrapolation of plot-related data to areas comparable to land use or landscape units. Vegetation indices calculated from satellite images are usually considered as indicators of green phytomass and are used for its areal estimates. The study solves the problem of establishing the information content of the normalized difference vegetation index NDVI depending on the fractional structure of living and dead aboveground phytomass, seasonal dynamics of the biological cycle, hydrothermal conditions and landscape position. We used the results of monthly measurements of aboveground phytomass fractions at 13 sites covered by Stipa zalesskii and Stipa lessingiana formations in the Burtinskaya steppe (Orenburgsky nature reserve) from May to September in 2015–2020. For each period, NDVI values were calculated from Landsat satellite images at all sites. Hypotheses about geobotanical, hydrothermal, phenological and landscape factors of NDVI informativity were tested by using the Spearman correlation coefficients, analysis of variance and multiple regression. The discrepancy between the seasonal peaks of NDVI and green phytomass is not consistent with the common opinion of a direct indicator value of NDVI. The total live biomass correlates more clearly with the index in June and July but weaker at the end of the season. NDVI turned out to be sensitive not so much to green phytomass as such, but to the mass and proportion of forbs and the ratio of live and dead phytomass. In late spring and early summer, NDVI is most closely associated with forbs while in July – with grasses. The hypothesis about the possibility of screening green mass with standing dead biomass was confirmed, which leads to a decrease in NDVI despite the absence of a decrease in green phytomass. NDVI may underestimate the real green phytomass if there is a sharp increase in the mass of dead biomass, usually in the second half of summer and early autumn. NDVI more adequately reflects the state of the aboveground phytomass of steppe communities that have not been exposed to fires for a long time, compared to burned communities and fallows.

Demand for Basketball: A Comparison of the WNBA and NBA

Abstract: There is considerable discussion regarding interest in women’s basketball, with critics often comparing the Women’s National Basketball Association (WNBA) and the National Basketball Association (NBA). This comparison is problematic because the WNBA is in an early growth phase while the NBA organizational life cycle position is far more mature. We investigate whether the demand features of early growth leagues are similar by comparing attendance data from the 8th-21st seasons of the WNBA with attendance from the same point in NBA history and the current NBA. We find the factors that affect demand in the WNBA are uniquely different than the NBA in both size and significance in either period; thus, it is inappropriate to compare the two leagues.

Multi-Objective Optimization of Fiber Laser Cutting of Stainless-Steel Plates Using Taguchi-Based Grey Relational Analysis

Stainless-steel has become a widely preferred material type in the marine, aerospace, sanitary, industrial equipment, and construction industries due to its superior corrosion resistance, high mechanic properties, high strength, formability, and thermal and electrical conductivity. In this study, a multi-objective optimization method based on grey relational analysis was employed to optimize the fiber laser-cutting parameters of cutting speed, focal position, frequency, and duty cycle. Surface roughness and kerf width, which are the two most important parameters that determine laser-cutting quality, were simultaneously optimized. In order to assign the optimum level of each parameter individually, the Taguchi technique was applied. The cutting surface morphology was examined according to the grey relational grade with a 3D optical profilometer, and maps of the cutting surfaces were created. According to the results achieved using Analysis of Variance (ANOVA), it was seen that the parameters that affected surface roughness and kerf width the most were duty cycle, with a contribution rate of 49.01%, and frequency, with a contribution rate of 31.2%. Frequency was the most important parameter in terms of multiple responses, with a contribution rate of 18.55%. Duty cycle and focal position were the second and third most effective parameters, respectively. It was determined that the optimum parameter values for minimum surface roughness and minimum kerf width that could be obtained with the fiber laser cutting of 20 mm thick AISI 304L (DIN EN 1.4301) material were 310 mm/min cutting speed, −11 mm focal position, 105 Hz frequency, and 60% duty cycle.

The effect of reverse factoring financial changes on supply chain

The consequences of reverse factoring in a supply chain are examined in this article. Reverse factoring occurs when a buying firm offers a reduced short-term borrowing rate to a supplier company in exchange for longer payment terms. From the standpoint of a supplier, this paper investigates the impact of rating changes, interest rate fluctuations, and business cycle position on the cost-benefit trade-off in the SMEs and manufacturing companies. However, the data was collected using a questionnaire. The main result is that changes in critical financial variables like ratings, news alerts and interest rates will shift former win–win circumstances for the supplier dependent on the business cycle into win–lose situations for the supplier. Overall, the reverse factoring results reveal sophisticated trade-offs, necessitating careful consideration in managerial decisions.

Cyclic Analogs of Desferrioxamine E Siderophore for 68Ga Nuclear Imaging: Coordination Chemistry and Biological Activity in Staphylococcus aureus.

As multidrug-resistant bacteria are an emerging problem and threat to humanity, novel strategies for treatment and diagnostics are actively sought. We aim to utilize siderophores, iron-specific strong chelating agents produced by microbes, as gallium ion carriers for diagnosis, applying that Fe(III) can be successfully replaced by Ga(III) without losing biological properties of the investigated complex, which allows molecular imaging by positron emission tomography (PET). Here, we report synthesis, full solution chemistry, thermodynamic characterization, and the preliminary biological evaluation of biomimetic derivatives (FOX) of desferrioxamine E (FOXE) siderophore, radiolabeled with 68Ga for possible applications in PET imaging of S. aureus. From a series of six biomimetic analogs, which differ from FOXE with cycle length and position of hydroxamic and amide groups, the highest Fe(III) and Ga(III) stability was determined for the most FOXE alike compounds–FOX 2-4 and FOX 2-5; we have also established the stability constant of the Ga-FOXE complex. For this purpose, spectroscopic and potentiometric titrations, together with the Fe(III)–Ga(III) competition method, were used. [68Ga]Ga-FOXE derivatives uptake and microbial growth promotion studies conducted on S. aureus were efficient for compounds with a larger cavity, i.e., FOX 2-5, 2-6, and 3-5. Even though showing low uptake values, Fe-FOX 2-4 seems to be also a good Fe-source to support the growth of S. aureus. Overall, proposed derivatives may hold potential as inert and stable carrier agents for radioactive Ga(III) ions for diagnostic medical applications or interesting starting compounds for further modifications.

Supply Chain Finance: Cost–Benefit Differentials under Reverse Factoring with Extended Payment Terms

This article studies the effects of reverse factoring in a supply chain when the buyer company facilitates its lower short-term borrowing rates to the supplier corporation in return for extended payment terms. We explore the role of interest rate changes, rating changes, and the business cycle position on the cost and benefit trade-off from a supplier perspective. We utilize a combined empirical approach consisting of an event study in Step 1 and a simulation model in Step 2. The event study identifies the quantitative magnitude of central bank decisions and rating changes on the interest rate differential. The simulation computes with a rolling-window methodology the daily cost and benefits of reverse factoring from 2010 to 2018 under the assumption of the efficient market hypothesis. Our major finding is that changes of crucial financial variables such as interest rates, ratings, or news alerts will turn former win–win into win–lose situations for the supplier contingent to the business cycle. Overall, our results exhibit sophisticated trade-offs under reverse factoring and consequently require a careful evaluation in managerial decisions.

The effects of public debt accumulation and business cycle on government spending multipliers

ABSTRACT We examine the impact of public debt changes as well as the effects of the business cycle on the expenditure multipliers. We adopt the structural vector autoregressive (SVAR) methodology on quarterly data for a sample of 18 OECD countries. The results show that expenditure multipliers are sensitive to the fiscal position, particularly the public debt changes as well as the business cycle. In particular, fiscal multipliers recorded high size in recessions than in expansions, in line with the recent findings about fiscal multipliers. Considering the public debt, leads to larger multipliers in debt accumulation under recessions than in debt accumulation under expansions. Many studies confirmed weak fiscal multipliers in expansions than in recessions, while others confirmed lower multipliers for countries with weak fiscal position. Our paper adds to this literature by joining the two effects of the business cycle and fiscal position, showing that fiscal position acts to lower multipliers when debt is rather accumulated in times of expansion than in recessions. We conclude that in times of expansion, the accumulated public debt effects are likely transmitting through Ricardian equivalence effect and concerns from expected high long-term interest rate leading to crowding-out effect, thus, lowering fiscal multipliers.

Numerical Simulation of the Effect of Freeze–Thaw Cycles on the Durability of Concrete in a Salt Frost Environment

In order to improve the accuracy of the analysis of the impact of freeze–thaw cycle on concrete durability in a salt freezing environment, the numerical simulation of the impact of the freeze–thaw cycle on concrete durability in a salt freezing erosion environment is studied in this paper. Firstly, considering the influence of axial force and bending moment on the relationship between bending moment and curvature, a concrete fiber beam column model is established. Then, according to the joint influence of temperature field, stress field and seepage field on concrete in the process of freezing and thawing, the control differential equation of the freezing and thawing cycle is established. The freeze–thaw damage section is divided, the non-uniform distribution of freeze–thaw damage is determined, and the division of the freeze–thaw damage section is completed. According to the linear relationship between freeze–thaw damage degree, relative dynamic elastic modulus, freeze–thaw cycle times and position variables, the durability of concrete is numerically simulated, and the attenuation law of bond strength at different section depths after freeze–thaw is determined. The results show that the temperature curve simulated by the design method is consistent with the actually measured temperature curve, which can better reduce the temperature change of the inner core of the test block during freezing and thawing, and the relative dynamic elastic modulus is in good agreement with the actual value, which can prove that the method in this paper has certain practical application value. It is expected to provide some reference for solving the durability problem of concrete in a salt frost erosion environment and the optimal design of concrete structures.

Trajectory-based energy landscapes of gene regulatory networks

Multistability and natural biological variability can result in significant heterogeneity within a cell population, leading to challenges in understanding and modulating cell behavior. Energy landscapes can offer qualitatively intuitive visualizations of cell phenotype and facilitate a more quantitative understanding of cellular dynamics, but current methods for landscape generation are mathematically involved and often require specific system properties (e.g., ergodicity or independent gene/protein probability distributions) that do not always hold. Here, we present a simple kinetic Monte Carlo-based method for landscape generation from a system of ordinary differential equations using only simulation trajectories initialized throughout the phase space of interest. The resulting landscape produces three quantitative features relevant to understanding cell behavior: stability (reflected by the depth or potential of landscape valleys), velocity (representing average directional movement on the landscape), and variance in velocity (indicative of landscape positions with heterogeneous movements). We applied this method to a genetic toggle switch, a core decision-making network in binary cellular responses, to elucidate effects of biologically relevant intrinsic and extrinsic cues. Intrinsic noise, such as stochasticity in transcription-translation and differences in cell cycle position, manifests through changes in valley width and position, reflecting increased population heterogeneity and more probabilistic cell fate transitions. The landscapes also capture the effect of an external inducer, revealing a quantitative correlation between the rate of cell fate transition and the energy barrier above a threshold inducer concentration determined by the permissivity of the valley. Further, in tracking dynamically changing landscapes under time-varying external cues, we unexpectedly found that an oscillatory inducer input can modulate cell fate heterogeneity and lead to periodic cell fate transitions entrained to the input frequency, depending on the intrinsic degradation rate of the switch. The landscape generation approach outlined herein is generalizable to other network topologies and may provide new quantitative insights into their dynamics.

Modelling cyclical variation in the cost pass-through: a regime-dependent approach

In this study a regime-dependent ARDL model is developed in order to investigate how labour costs feed through into prices conditional on the business cycle position. Its estimates enable inference on the cyclical behaviour of markups. The proposed methodology is applied to the Polish industrial sectors. The obtained estimates point to procyclicality as the prevailing pattern of markup adjustment. Thus, overall markups in the Polish industry seem to have a mitigating effect on business cycle fluctuations. The degree of procyclicality seems, however, to be positively correlated with the degree of the industry’s competitiveness.

Inhibitory effects of iron depletion plus eribulin on the breast cancer microenvironment

BackgroundIron is required for the proliferation of cancer cells, and its depletion suppresses tumor growth. Eribulin mesylate (eribulin), a non-taxane microtubule inhibitor, disrupts the tumor microenvironment via vascular remodeling and obstruction of the epithelial-mesenchymal transition (EMT). Herein, we investigated the effects of the iron chelator on tumor-related properties of breast cancer cells and the effects of iron chelator plus eribulin on tumor growth in vivo.MethodsTwo triple-negative breast cancer (TNBC) cell lines, MDA-MB-231 and BT-549, and one hormone-receptor positive breast cancer cell line, MCF-7, were used in our study. Cell proliferation, cell migration, cell cycle position, and gene expression were analyzed via MTT assays, wound-healing assays, flow cytometry, and quantitative real-time-polymerase chain reaction, respectively. For the in vivo experiments, mice with breast cancer xenografts were treated with the inhibitors, alone or together, and tumor volume was determined.ResultsIron chelator inhibited breast cancer cell proliferation and decreased the proportion of S-phase cells. Conversely, it induced hypoxia, angiogenesis, EMT, and immune checkpoints, as determined by quantifying the expression of marker mRNAs in MDA-MB-231 and MCF-7 cells. Eribulin suppressed the expression of the hypoxia and EMT related marker mRNAs in the presence of iron chelator. Iron chelator plus eribulin inhibited tumor growth in vivo to a greater extent than did either inhibitor alone.ConclusionsAlthough iron chelator induces oncogenic events (hypoxia, angiogenesis, EMT, and immune checkpoints), it may be an effective treatment for breast cancer when administered in combination with eribulin.