Periodic Variations Research Articles

Analysis of the evolution in the number of manufacturing companies in Portugal between 2009 and 2021 to understand growth and decline trends

This project analyzes the evolution of the manufacturing sector in Portugal from 2009 to 2021, focusing on the variations in the number of active companies across various subcategories, such as food, textiles, and metal product industries. The goal of this analysis is to understand the dynamics of growth and contraction within each sector, providing insights for companies to adjust their market and operational strategies. Key objectives include analyzing the overall evolution in the number of companies, identifying subcategories with notable changes, and providing a comprehensive analysis of observed trends and patterns. The study is based on data from PORDATA 2024, and the research employs temporal trend analysis, linear and quadratic regression, and the Pareto representation to identify patterns of growth and decline. By comparing annual data, the project uncovers periods of growth and decline, allowing for a deeper understanding of the sector’s dynamics. The findings also highlight variations in periods of economic crises and during the Covid-19 pandemic, and recommendations for action are presented to support businesses resilience and continuity. These results are valuable for companies within the manufacturing sectors analyzed and policy makers, guiding strategic decisions to navigate the complexities of the market dynamics and to ensuring long-term organizational sustainable success.

Anomalous pumping in the non-Hermitian Rice-Mele model.

We study topological charge pumping (TCP) in the Rice-Mele (RM) model with irreciprocal hopping. The non-Hermiticity gives rise to interesting pumping physics, owing to the presence of skin effect and exceptional points. In the static one-dimensional (1D) RM model, we find two independent tuning knobs that can drive the topological transition, namely, non-Hermitian parameter $\gamma$ and system size $N$. To elucidate the system-size dependency, we use a finite-size generalized Brillouin zone (GBZ) scheme to show that the edge modes can be distinguished from the non-hermiticity induced skin modes. Moreover, this scheme can capture the state pumping of topological edge modes as a function of $\gamma$ in the static 1D RM model and it further provides insight into engineering novel gapless exceptional edge modes with the help of adiabatic drive. Furthermore, we show that the standard topological pumping due to the adiabatic and periodic variation of the model parameters survives even with finite $\gamma$. However, we observe that it depends upon the driving protocols and strength of the non-Hermiticity ($\gamma$). With increasing $\gamma$, the adiabatic pumping for non-trivial protocols is destroyed first and then re-emerges as an anomalous pumping which does not have any Hermitian counterpart. Additionally, we observe that even a trivial adiabatic protocol can give rise to pumping as opposed to the Hermitian system. This is attributed to the inherent point gap physics of non-Hermitian system which we explain by reformulating a non-Bloch topological invariant for the 1+1D RM model. This invariant explains the number of pumped charges (in each period) for all the driving protocols.

Photometric Analysis of the Cataclysmic Variable Star LT Eri

Abstract LT Eri is a long-period eclipsing cataclysmic variable star (CV). This study investigates its outbursts, negative superhumps (NSHs), tilted-disk precession, eclipse-depth variations, and observed minus calculated (O – C) behavior, using photometric data from the Transiting Exoplanet Survey Satellite (TESS), the Zwicky Transient Facility, the All-Sky Automated Survey for Supernovae, and the American Association of Variable Star Observers. Our analysis reveals an outburst period of 14.7(31) days, with variable periods ranging from 11.62(4) to 22.15(13) days. Both long and short outbursts were detected, lasting approximately 18 and 10 days, respectively. Analysis of the TESS photometry shows that the NSH period is updated to 0.16265161(7) days, persists during the outburst, and its amplitude is correlated with the outburst phase. A suspected signal of tilted-disk precession with a period of 3.5781(6) days is also detected. Additionally, the eclipse depth shows a periodic variation of 3.6270(9) days, closely matching the tilted-disk precession period; however, no biperiodic variation is found, as seen in the dwarf nova HS 2325+8205, suggesting that this phenomenon is not universal. An O – C analysis reveals a weak oscillation with a period of 3.5772(6) days. Our superposition of sine curves consistent with the NSH period and amplitude, along with mean eclipse curves, produces periodic O – C variations with a period of 3.6666(2) days. This indicates that the observed periodic variations in O – C, often around the disk precession period in CVs, may result from the beat between the NSHs and the eclipse rather than actual variations in the accretion disk.

Anomalous pumping in the non-Hermitian Rice-Mele model.

We study topological charge pumping (TCP) in the Rice-Mele (RM) model with irreciprocal hopping. The non-Hermiticity gives rise to interesting pumping physics, owing to the presence of skin effect and exceptional points. In the static one-dimensional (1D) RM model, we find two independent tuning knobs that can drive the topological transition, namely, non-Hermitian parameter $\gamma$ and system size $N$. To elucidate the system-size dependency, we use a finite-size generalized Brillouin zone (GBZ) scheme to show that the edge modes can be distinguished from the non-hermiticity induced skin modes. Moreover, this scheme can capture the state pumping of topological edge modes as a function of $\gamma$ in the static 1D RM model and it further provides insight into engineering novel gapless exceptional edge modes with the help of adiabatic drive. Furthermore, we show that the standard topological pumping due to the adiabatic and periodic variation of the model parameters survives even with finite $\gamma$. However, we observe that it depends upon the driving protocols and strength of the non-Hermiticity ($\gamma$). With increasing $\gamma$, the adiabatic pumping for non-trivial protocols is destroyed first and then re-emerges as an anomalous pumping which does not have any Hermitian counterpart. Additionally, we observe that even a trivial adiabatic protocol can give rise to pumping as opposed to the Hermitian system. This is attributed to the inherent point gap physics of non-Hermitian system which we explain by reformulating a non-Bloch topological invariant for the 1+1D RM model. This invariant explains the number of pumped charges (in each period) for all the driving protocols.

Model-Free Speed Control for Pumping Kite Generator Systems Based on Nonlinear Hyperbolic Tangent Tracking Differentiator

This paper investigates the emerging field of grid-connected wind-powered pumping kite generator system (PKGS), focusing on the challenges associated with the generator/motor speed control. Conventional use of proportional–integral (PI) controllers faces difficulties in meeting requirements for dynamic response, tracking performance, stability, and disturbance rejection encountered in this technology, notably the periodical variation in the rotational speed reference in maximum power point tracking in generation phases and the dynamic response for the step reference in transient ones. To overcome these limitations, a model-free controller (MFC) approach is introduced, also known as intelligent PID controllers. Unlike traditional methods, MFC does not rely on a control model of the system and adapts to uncertainties and disturbances through online estimation based on the system’s input–output behavior. To further improve the control performances, a tracking differentiator based on a nonlinear hyperbolic tangent function is integrated in the MFC. The effectiveness of the proposed strategy is proved through simulations in MATLAB/Simulink. The results highlight the superior performances of the proposed MFC approach in terms of speed control accuracy, response time, and robustness.

Determining the Nature of IC 10 X-2: A Comprehensive Study of the Optical/IR Emission from an Extragalactic BeHMXB

We present a comprehensive analysis of the optical and infrared (IR) properties of high-mass X-ray binary (HMXB) IC 10 X-2, classified as a supergiant HMXB and superfast X-ray transient by previous work. Our analysis of regular (daily and weekly) observations by both the Zwicky Transient Facility and Las Cumbres Observatory over a 5 yr period indicates both periodic flares and variations in the apparent magnitude and color with a period of ∼26.5 days—likely the orbital period of this binary system. The periodic flaring suggests the stellar companion is a Be star, with flares resulting from increased accretion onto the neutron star (NS) when it enters the stellar decretion disk. The periodic variations in the optical/IR brightness and color likely result from orbital variations in the hydrogen column density along the line of sight or a transient accretion disk around the NS. Lastly, the numerous short-duration episodes where IC 10 X-2 is significantly “redder” or “bluer” than normal likely result from clumps within this system—which can accrete onto the NS (causing IC 10 X-2 to appear bluer) or pass through the line of sight (causing IC 10 X-2 to appear redder). These results substantially increase our understanding of the evolution of this source, which is a significant source of ionizing photons in its host galaxy IC 10, a low-mass, metal-poor starburst galaxy similar in many respects to those thought to be common in the early Universe.

The Periodic Variation in Iron Availability in Soils Affected by Saline Water Conditions

The Periodic Variation in Iron Availability in Soils Affected by Saline Water Conditions

A DUGKS study of rarefied gas flowing in a square cavity under harmonic heating

In order to examine the impact of wall temperature change on the flow and heat transfer properties of rarefied gases in restricted space, the discrete unified gas kinetic scheme (DUGKS) is applied to the simulation of the thermal creep flows in a square cavity. All the boundaries of the cavity are stationary and diffuse reflection walls. The left and right walls have a lower temperature, and the upper and lower ones are under harmonic heating. The simulation parameters considered in the present work are set as follows: the Knudsen number 0.01 ≤ <i>Kn</i> ≤ 10, temperature change frequency 0.5 ≤ <i>St</i> ≤ 5, and Temperature change amplitude 0.1 ≤ <i>A<sub>h</sub></i> ≤ 0.8. The results indicate that the velocity and temperature fields in the cavity exhibit periodic variations. No inverse Fourier heat transfer phenomenon was observed within the parameter ranges studied. The intensity of the thermal creep flow can be increased by increasing the frequency and amplitude of the temperature, and the Knudsen number. This can also raise the temperature jump and velocity slip close to the temperature change walls. Heat transfer lag and a reduction in the wall's heat transfer capability are caused by increases in <i>St</i> and <i>Kn</i>. When <i>St</i> = 0.5 is small, a complex vortex structure is seen in the cavity. As the value of <i>St</i> rises to 5, the vortex disappears, the gas travels from the variable temperature wall to the cavity's horizontal centerline, and the region close to the middle of the left and right walls changes from an endothermic to an exothermic zone. Furthermore, the temperature and velocity fields inside the cavity hardly change, but the degree of heat transfer on the wall decreases with larger <i>A<sub>h</sub></i>. This work offers helpful recommendations for the design of MEMS devices that use pulsing heating.

The dynamic characteristics of the shearer cable drag system.

Based on the 5615 working face of Beisu Coal Mine, a virtual prototype of the shearer cable drag system was developed using the MG2×70/325-BWD electric traction shearer as the carrier, in combination with CERO and ADAMS software. The shearer cable was equivalently modeled using the discrete rigid body method to study the dynamic characteristics of the drag system. This research provides a foundation for the design and optimization of both the cable and cable clamps. The results indicate that during the bending process of ordinary and reinforced cables in the cable drag system, the tensile force between the cable clamps increases from approximately 28 N and 37 N to a maximum value of 133 N and 146 N, respectively, before decreasing to around 57 N and 66 N. At the connection point between the drag system and the shearer, the tensile force between the cable clamps fluctuates and increases, reaching a maximum value of 925.2 N and 1134.7 N when the shearer reaches the end of the working face. These values are significantly lower than the cable clamp's breaking tensile strength of 70 kN, with peak values of 57.4 N and 94.1 N, respectively. During the cable bending process, The contact force with the cable clamp continuously changes with the bending angle, During 0 ~90°, the contact force between ordinary and reinforced cable and cable clamp gradually increases to the maximum values 61.3N and 86.2N, After 90 have plummeted to near 23 N and 25 N, In the process of dragging the cable to the top of the roller, it fluctuates between 45.2~51.7 N and 66.3~73.6 N respectively, Cable exit bends are slowly reduced to fluctuations around 16 N and 17 N, The tensile force between ordinary and reinforced discrete cables increased to around 58.4 N and 80.5 N and then decreased to around 12.6 N and 32.8 N, respectively. During the bending process of reinforced cables, the average contact force with the cable clamps increased by 22.3 N compared to the ordinary cables, while the average discrete tensile force between the cables increased by 18.7 N. Although the tensile and contact forces of the reinforced cable are slightly higher than those of the ordinary cable, the reinforced cable has a higher safety factor and greater adaptability. The drag motion of the cable is correlated with the characteristics of the ring-chain drive, and the drag speed and tensile force exhibit periodic variations due to the polygonal effect of the chain drive. The findings provide valuable insights for intelligent cable drag research and lay the foundation for the optimization of mining cables and cable clamps.

The radiologic perspective of pulmonary tuberculosis seasonality in south-south Nigeria

Background: The periodic variation in the occurrence of disease within a calendar period is relatively common among many diseases, especially infectious diseases like tuberculosis (TB). Objective: The study is to radiologically evaluate the seasonality of pulmonary tuberculosis in our environment. Materials and Method: The study was a descriptive cross-sectional study over a period of 6 years (2017-2022) with one thousand, three hundred and fifty (1350) chest radiographs diagnosed of pulmonary tuberculosis. The chest radiographs were reviewed by three Radiologists with certification from the Faculty of Radiology of the West African College of Surgeons or the National Postgraduate Medical College of Nigeria. The data was analyzed descriptively using the statistical package for social science, SPSS version 23.0. Result: The monthly time series distribution of the radiologic diagnosis of pulmonary tuberculosis showed the lowest occurrences in the year 2020. The monthly average Seasonal Index of the radiologic occurrence of pulmonary TB shows that the months of June (1.29), July (1.95), and August (2.09) demonstrated the highest average seasonal index. The monthly averages from January to December over the 6 years of the study showed the highest occurrences in the month of August, and the lowest occurrences in the month of October. Conclusion: Although there were inconsistencies in the monthly pattern over the six year period, the highest incidence was in the month of August, followed by the month of July. Thus the study concludes that there exist seasonal variations in the radiologic diagnosis of pulmonary tuberculosis.

Prognostic significance of preoperative prognostic nutritional index in hepatocellular carcinoma after curative hepatectomy: a meta-analysis and systemic review

BackgroundThe Prognostic Nutritional Index (PNI), which reflects both nutritional and immune status, has emerged as a potential predictor of survival outcomes in cancer patients. However, its role in forecasting the prognosis of hepatocellular carcinoma (HCC) following curative hepatectomy remains unclear. To further investigate the association between PNI and survival outcomes in HCC patients, we conducted a systematic review and meta-analysis.MethodsWe performed a comprehensive search across Web of Science, PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure to identify studies evaluating the prognostic value of PNI in HCC following curative hepatectomy. Overall survival (OS), recurrence-free survival (RFS), and disease-free survival (DFS) were extracted as primary outcomes. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using fixed-effect or random-effect models. Additionally, heterogeneity, publication bias, and sensitivity analyses were performed to evaluate the consistency and robustness of the obtained results.ResultsThis systematic review and meta-analysis included 19 studies comprising a total of 9,830 patients. The results indicated that higher PNI was significantly associated with longer overall survival (OS) (n = 6,812; HR = 1.60; 95% CI: 1.44–1.77; p < 0.001) and recurrence-free survival (RFS) (n = 8,529; HR = 1.48; 95% CI: 1.30–1.69; p < 0.001). There was significant heterogeneity among studies for RFS (I2 = 56.0%, p = 0.004). Subgroup analysis indicated that age, variations in PNI cutoff values and follow-up periods were the primary contributors to this heterogeneity. The trim-and-fill method indicated that publication bias did not impact the OS results, and Egger’s test found no publication bias for RFS (p = 0.104). Sensitivity analysis further confirmed the stability of these results.ConclusionPreoperative PNI is a significant prognostic indicator in HCC patients undergoing curative hepatectomy, with higher PNI correlating with improved survival outcomes.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024530150, identifier CRD42024530150.

Synthesis of Porous Anodic Alumina Featuring a Periodic Pore Structure by Regulating the Anode Temperature

Abstract Porous anodic alumina (PAA) with a periodic pore structure has been synthesized by using an innovative preparation method. The morphology of PAA pores can be modulated within the same electrolyte by adjusting the temperature of the aluminum anode, enabling periodic variations in pore size (Dp). The formation mechanism of PAA has been elucidated through analyses of micromorphology, anodization current density (ia), interpore distance (Dint), and Dp of the samples. Results indicate that the average Dint for the synthesized PAA is approximately 260–340 nm, while the average Dp ranges from 90 to 260 nm. Both ia and Dp exhibit periodic fluctuations corresponding to changes in anode temperature under consistent electrolyte conditions and anodization voltage (Ua). Lateral pores are generated via a phosphoric acid etching process, resulting in PAA with a distinctive three-dimensional interconnected pore architecture. Furthermore, ridges with an arc-like shape on the outer walls of PAA pores have been observed; their formation mechanism can be effectively explained by the convection model and the viscous flow model. These findings contribute significantly to achieving precise control over the pore structure of PAA.

Induction arrow spatial and temporal variations

The induction arrow C is a characteristic of the variable geomagnetic field at one observation point (x, y) for a certain period T of geomagnetic variations B. It visually describes the magnitude and direction of the deviation of the geomagnetic field vector from the horizontal plane. The induction arrow is nonzero only when the vertical component Bz appears. Bz appears in three cases: 1) electrical conductivity’s horizontal gradients under the surface of the globe; 2) incomplete compensation of the vertical component of the primary field of the ionosphere-magnetosphere source by the secondary field induced in the horizontally layered Earth. The degree of compensation systematically changes during the day, year..., leading to temporal variations in the induction arrow (source effect); 3) the appearance of not-removed noise or lithosphere emission containing Bz. This article presents the spatial and temporal variations of the induction arrows. Real (in-phase) and imaginary (out-of-phase) induction arrows (vertical response functions or tippers) were obtained for every day with proper observations from 1991 to 2014 years for five intervals of periods: 150—300 s, 300—600 s, 600—1200 s, 1200—2400 s, 2400—3600 s, calculated from three components of geomagnetic field recorded at 137 observatories of the global network INTERMAGNET. To reduce the scatter, the daily values were recalculated to monthly values. Such global material from +87° to –88° of geomagnetic latitude was obtained for the first time and its analysis yielded new scientific results. The annual variations (with a period one year) are visible at about 2/3 of the observatories (at the other observatories, they are below the background level of shorter period variations and/or noise). Its amplitude strongly depends on the geomagnetic latitude and sometimes reaches such a high value as 0.4—0.5 (peak-to-peak) at high (>65°) latitudes and varies within 0.01—0.15 at middle and low latitudes. Previous studies at middle latitudes discovered that the annual variations in the northern component Au is positive everywhere (maximum in June, minimum in December) and proposed, as a global source model for the annual variations explanation, the ring current at the height 3―6 Earth’s radii. We discovered that at high latitudes, Au is usually negative. We propose to explain all the observed features of the induction arrow’s annual variations by variations of the ionosphere currents in the aurora zone. 11-year variations are found at ≈30 % of observatories located at all latitudes but more frequently in aurora zones. At a few observatories, trends (monotonous changes in arrows) were found. The largest trend of magnitude 0.2 for all periods was found in southern Greenland, where glaciers have been melting rapidly over the past 30 years, which makes it possible to associate both trends with global warming. In a few aurora observatories of North America trends of magnitude ≈0.1 were noticed. In these same years, the North Magnetic Pole unusually rapidly migrated for 1100 km in 23 years. It can be assumed that these trends are related to changes in the aurora oval position. At geomagnetic latitudes from –78° to +78°, the main harmonic (24 hours=86400 s) of daily variations of the geomagnetic field is always accompanied by at least one higher order harmonic 24/n (n=1÷7). At higher latitudes >78° of both hemispheres only the fundamental 24-hour harmonic is visible. Induction arrow temporal variations create difficulties in determining its constant component used to study the electrical conductivity of the Earth’s crust and upper mantle but can be very useful for geodynamic processes study

Metal Transfer Behavior and Molten Pool Dynamics in Cold Metal Transfer Pulse Advanced Additive Manufacturing of 7075 Aluminum Alloy.

Wire arc additive manufacturing (WAAM) with a special arc mode of cold metal transfer pulse advanced (CMT-PADV) is an ideal additive manufacturing process for fabricating aerospace components, primarily high-strength aluminum alloys, offering advantages such as high deposition rates and low cost. However, the numerical simulation of the CMT-PADV WAAM process has not been researched until now. In this study, we first developed a three-dimensional fluid dynamics model for the CMT-PADV WAAM of 7075 aluminum alloy, aiming at analyzing the droplet transition and molten pool flow. The results indicate that, under the CMT-PADV mode, droplet transition follows a mixed transition mode, combining short-circuiting and spray transition. The Direct Current Electrode Positive period of the arc accelerates droplet spray transition, significantly increasing molten pool flow. In contrast, the Direct Current Electrode Negative period of the arc predominantly features droplet short-circuiting transition with low heat input and a weak impact on the molten pool. The periodic switching of the current polarity of CMT-PADV mode results in periodic variations in molten pool size and volume, reducing heat input while maintaining high deposition quality. The revelation of this mechanism provides process-based guidance for low-defect, high-performance manufacturing of critical components.

Cataract Surgery and Intraocular Lens Implantation in Aviation Pilots.

The rising age of pilots and the extension of retirement age underscore the importance of investigating Presbyopia correction intraocular lenses during cataract surgery for Aviation Pilots. This study aims to assess recommendations from aviation regulatory agencies, providing guidance on the use of multifocal intraocular lenses in both commercial and military pilots. A review analysed the perspectives of aviation regulatory agencies regarding the implantation of multifocal intraocular lenses in pilots. Findings reveal a lack of consensus among agencies regarding the use of multifocal intraocular lenses. Some adopt a permissive stance, permitting their use, while others maintain restrictive approaches. Variations in the post-cataract surgery unfit assessment period were observed, ranging from six to twelve weeks. The implantation of multifocal intraocular lenses in aviation pilots remains contentious. Further research is crucial to address unresolved aspects associated with using multifocal intraocular lenses in this context.

Experimental simulation of friction and wear between carbon fiber tow and heddle eye under periodic tension during the 3D weaving process

AbstractWeaving is the predominant technology for fabricating carbon fiber composite preforms. Carbon fibers are subjected to various forms of reciprocating friction in the weaving process. Especially, the friction between carbon tow and heddle eyes is difficult to describe due to the complex conditions of variable tension. In this study, a novel experimental simulator was developed to characterize the friction behavior between warp yarn and heddle eye under periodic tension variation. The friction force (Ff) and coefficient of friction (COF) under variable tension conditions were tested. To investigate the variation of real contact area between carbon tow and heddle eyes under variable tension conditions, a silicon‐film indentation method was developed, and the effect of pre‐tension on carbon tow was obtained by combining three‐dimensional micro surface morphology and Hertz analysis methods. The results indicated that both the COF and Ff decreased with increasing pre‐tension. 3D morphology analysis suggested that the tow contact area reached its maximum when the pre‐tension was 1.2 N. In the Hertzian calculation of the actual contact area, the change of the contact area and the pre‐tension was generated by taking into account the evolving contact length, which differed from the measured friction force value by a constant factor.Highlights A variable tension device was designed and developed. The friction between carbon tow and heddle eye was simulated under variable tension. The Ff and COF under different pre‐tensions were tested. A silicon‐film indentation method was proposed. The relationship between contact area and friction was studied.

Combined Impacts of Thermal and Mass Stratification on Unsteady MHD Parabolic Flow Along an Infinite Vertical Plate With Periodic Temperature Variation and Variable Mass Diffusion

ABSTRACTThis study investigates the dynamics of unsteady MHD parabolic flow along an infinite vertical plate, with a focus on the impacts of thermal and mass stratification under periodic temperature variations and variable mass diffusion. Utilizing the Laplace transform technique for deriving exact solutions, this research innovatively integrates both thermal and mass stratification effects without resorting to approximations. The main objective is to assess how these stratifications influence flow dynamics, temperature, and concentration profiles in environments with varying magnetic fields. The study contrasts these findings against classical non‐stratification cases, offering a detailed comparison of fluid behavior under different conditions. Results indicate that thermal and mass stratifications substantially decrease velocity and stabilize temperature profiles, pointing to a damping effect on fluid motion while also controlling diffusion processes. These stratifications lead to higher Nusselt and Sherwood numbers, suggesting improved heat and mass transfer efficiencies. In contrast, the absence of stratification results in higher velocities and less stable temperature and concentration distributions. The findings underscore the significant role of stratification in optimizing fluid dynamics and enhancing the efficiency of heat and mass transfer processes, providing crucial insights for engineering and environmental applications where such conditions prevail.

Biophysical mechanism of animal magnetoreception, orientation and navigation

We describe a biophysical mechanism for animal magnetoreception, orientation and navigation in the geomagnetic field (GMF), based on the ion forced oscillation (IFO) mechanism in animal cell membrane voltage-gated ion channels (VGICs) (IFO-VGIC mechanism). We review previously suggested hypotheses. We describe the structure and function of VGICs and argue that they are the most sensitive electromagnetic sensors in all animals. We consider the magnetic force exerted by the GMF on a mobile ion within a VGIC of an animal with periodic velocity variation. We apply this force in the IFO equation resulting in solution connecting the GMF intensity with the velocity variation rate. We show that animals with periodic velocity variations, receive oscillating forces on their mobile ions within VGICs, which are forced to oscillate exerting forces on the voltage sensors of the channels, similar or greater to the forces from membrane voltage changes that normally induce gating. Thus, the GMF in combination with the varying animal velocity can gate VGICs and alter cell homeostasis in a degree depending, for a given velocity and velocity variation rate, on GMF intensity (unique in each latitude) and the angle between velocity and GMF axis, which determine animal position and orientation.

Roles of ecological and hydrological processes in the variability of carbon fluxes in a salt marsh of the Yangtze Estuary: Model simulations vs. measurements

Carbon exchange in coastal wetlands is a complex biochemical process regulated by a combination of meteorological, plant-soil, and hydrological factors. In the Yangtze Estuary, a process-based carbon flux model was developed to further elucidate the spatiotemporal dynamics of carbon fluxes of different marsh species and elevations, incorporating the roles of climatic, hydrological, and geographical factors. The model was validated based on measurements of CO2 and CH4 fluxes using the static chamber and eddy covariance methods. The results showed that the model reproduced well the time series of the net ecosystem change (NEE) and CH4 flux from diel to half-month scales. During tidal cycling, the ecosystem CO2 and CH4 fluxes were suppressed under inundation, and the magnitude of suppression was proportional to the water depth. The landform of the tidal flat determined the submerged height and duration, and the hydrological effects on carbon fluxes varied with elevation. The model also reasonably reflected the negative correlation between tidal height and salinity and carbon fluxes during the spring-neap cycle. Sensitivity tests revealed that temperature and tidal height were the two most critical factors affecting the carbon fluxes. Wavelet coherence analysis further indicated that temperature and tidal height explained most of the periodic variations in NEE at the diel scale. Specifically, temperature dominated CH4 emission dynamics in spring and winter, whereas tides replaced temperature as the dominant factor in summer. The temperature also exhibited a stronger coherent intensity at high elevations, whereas the influence of tides was greater in low-lying regions. This study emphasizes the associated effects of climatic, biological, and hydrological factors on the spatiotemporal heterogeneity of carbon fluxes in the coastal marshes. This coupled model is expected to be beneficial for estimating the carbon sequestration capacity in China's coastal salt marshes under global change conditions.

Observing periodic gap variations in cuprates

The presence of multiple orders in strongly correlated electronic materials like the cuprate superconductors, coupled with spatial inhomogeneity, poses a challenge to the interpretation of spectroscopic data taken on them. Here, we present a technique that directly acknowledges these orders and inhomogeneities and extracts statistically significant features from such data. Applying this technique to scanning tunneling spectroscopy measurements from single and bilayer cuprates spanning a wide doping range, we peer through local inhomogeneities and identify a gaplike feature that breaks translational and rotational symmetries and varies periodically in a fourfold pattern. This identification of spectral features aligns well with theoretical predictions of spatially modulated pair density. Published by the American Physical Society 2024