Cycle Phenomena Research Articles

Transgenic rats expressing dominant negative BMAL1 showed circadian clock amplitude reduction and rapid recovery from jet lag.

The circadian rhythms are endogenous rhythms of about 24h, and are driven by the circadian clock. The clock centre locates in the suprachiasmatic nucleus. Light signals from the retina shift the circadian rhythm in the suprachiasmatic nucleus, but there is a robust part of the suprachiasmatic nucleus that causes jet lag after an abrupt shift of the environmental lighting condition. To examine the effect of attenuated circadian rhythm on the duration of jet lag, we established a transgenic rat expressing BMAL1 dominant negative form under control by mouse Prnp-based transcriptional regulation cassette [BMAL1 DN (+)]. The transgenic rats became active earlier than controls, just after light offset. Compared to control rats, BMAL1 DN (+) rats showed smaller circadian rhythm amplitudes in both behavioural and Per2 promoter driven luciferase activity rhythms. A light pulse during the night resulted in a larger phase shift of behavioural rhythm. Furthermore, at an abrupt shift of the light-dark cycle, BMAL1 DN (+) rat showed faster entrainment to the new light-dark cycle compared to controls. The circadian rhythm has been regarded as a limit cycle phenomenon, and our results support the hypothesis that modification of the amplitude of the circadian limit cycle leads to alteration in the length of the phase shift.

Bifurcation Analysis of the Regulatory Modules of the Mammalian <i>M/G<sub>1</sub></i> Phase with Time Delay

G0/G1 “gaps” joint the S phase and M phase to form the cell cycle. The dynamics of enzyme reaction to drive the target protein production in M phase is analyzed mathematically. Time delay is introduced since the signal transmission need time in G0/G1 “gaps” phase. Hopf bifurcation of DDEs model is analyzed by applying geometrical analytical method. The instability oscillating periodic solutions arise as subcritical Hopf bifurcation occurs. The Hysteresis phenomena of the limit cycle are also observed underlying the saddle-node bifurcation of the limit cycle. Due to stability switching, interestingly, the bifurcating periodical solution dies out near the vicinity of Hopf lines. By Lyapunov-Schmidt reduction scheme, the normal form is computed on the center manifold. Finally, it is verified that the theory analytical results are in coincidence with the numerical simulation.

Značaj monitoringa kvaliteta vode u jezerima hidroelektrana

When planning the construction of a hydroelectric power plant, an important segment is adequate monitoring of water quality. With an appropriate monitoring program, the multifunctional use of artificial lakes is enabled. Eutrophication (nutrient over-enrichment) of water in a lake is a phenomenon that has been noticed in all lakes. The consequence of eutrophication is the endangerment of the aquatic ecosystem. Eutrophication is a phenomenon that occurs as a response of the aquatic ecosystem to the increased concentration of nutrients, phosphorus (P) and nitrogen (N), due to natural and anthropogenic activities. Recent research indicates a correlation between local climate change and water circulation and the impact of climate change on all phenomena in the hydrological cycle. Temperature fluctuations, huge amounts of rain when precipitation is analysed, constant heating and increase in humidity all affect more intense eutrophication. The key conclusions of the research dealing with the construction of the hydroelectric power plant in Komarnica are: to introduce monitoring (permanent control) of water quality in lakes in order to minimize or control, even prevent eutrophication. Each artificial lake has its own unique characteristics. The dependence of chlorophyll, phosphorus and lake volume varies depending on the month, season and year. The proposal for the lake that will be built on Komarnica, which is part of the future hydroelectric power plant, is a monthly monitoring of the concentration of chlorophyll, nutrients and the volume of the lake. Seasonal monitoring depends on precipitation, hydrological and limnological characteristics and trends of dry and rainy episodes. Analyzes and previous research have shown that the introduction of mandatory parameters for monitoring water quality does not increase the cost of electricity production and energy conservation, but significantly improves and enhances the quality of the environment.

Phase sensitivity for coherence resonance oscillators

The phase reduction approach has manifested its power in analyzing the rhythmic behaviors for limit cycle oscillators. For coherent oscillation purely induced by noise, e.g., the coherence resonance oscillator, the stochastic dynamics exhibit almost deterministic limit cycle phenomenon which inspires the application of the phase reduction approach to this kind of systems. In this paper, the FitzHugh–Nagumo system in coherence resonance is modeled as a jump process. The phase sensitivity is obtained by applying the phase reduction approach for the hybrid system. A modified direct method is proposed to compare the theoretical results with those of Monte Carlo simulation for the stochastic system, which shows a relatively good agreement for the perturbation not being too small. The phase reduction results of the coherent oscillators are applied to two coupled FitzHugh–Nagumo neurons. It is interesting that the phase difference of the coupled coherent oscillators does not converge as the deterministic oscillators, but forms a distribution where the peaks and valleys correspond to the stable and unstable synchronizations predicted by the phase coupling functions. The idea in this paper could be applied to other coherent oscillators where the stochastic dynamics follow almost deterministic paths.

Study of diffusionless and diffusional transformations usingin situcooling and heating techniques in a scanning electron microscope

In situ electron microscopy can be an effective tool to investigate the underlying science of many transformation mechanisms in materials science. Useful utilization of these experimentations will provide greater insight into many of the existing theories, as microstructural changes can be visualized in real time under some applied constraints. In this study, we have investigated two basic phase transformation phenomena: diffusionless and diffusional mechanisms with the help of insitu cooling and heating techniques in scanning electron microscope (SEM). In situ cooling experiments have been carried out on secondary hardening ultra-high-strength steels to understand the diffusionless transformation of austenite to martensite. Nucleation and growth of the martensites have been observed with cooling in different steps to -194°C. Details of the formation of different variants of martensites in steel were studied with the help of orientation imaging microscopy. Diffusional transformations were studied in terms of oxidation of pure copper in SEM using in situ heating technique. Different heating cycles were adopted for different samples by in situ heating to a maximum temperature of 950°C for the oxidation study. Nucleation of copper oxides and subsequent growth of the copper oxides at different temperatures were studied systematically. Raman spectroscopy and orientation imaging were done to confirm the formation of oxides and their orientations. The thermal cycling phenomenon was replicated inside SEM with heating and cooling and it has been demonstrated how the nature of copper and its oxides changes with the thermal cycle. This article is part of a discussion meeting issue 'Dynamic in situ microscopy relating structure and function'.

Limit Cycle Detection in Line Start Interior Permanent Magnet Motors

A limit cycle phenomenon refers to an isolated closed trajectory of the states of a non-linear dynamic system in a two-dimensional phase space. Line start interior permanent magnet (LSIPM) motors often experience limit cycles due to variations in the load or supply, causing sustained oscillations in the drive system. This article presents an analysis of the limit cycle phenomenon in LSIPM motors, and proposes a method to detect its existence in the system using the stator current signal analysis in time-frequency domain. The proposed method is first validated by conducting the finite element analysis for a three-phase 1-HP 4-pole LSIPM motor under various limit cycle induced operating conditions. It is further validated experimentally in the lab using a 1-HP LSIPM motor drive. Both simulation and experimental results indicate that the proposed method can successfully detect the existence of limit cycles in LSIPM motor drives.

Hydrological Simulation of Runoff for a Watershed in Punpun Basin using SWAT

Runoff is a very important phenomenon of hydrological cycle and it is relevant for the watershed management programme for conservation and development or natural resources and its management. However, In India the availability of accurate information on runoff is very scarce and needs to be calculated empirically for further developments. The Soil and Water Assessment Tool (SWAT) is a physical parameter model which has been developed to estimate values for the runoff, sediment and nutrient carry off from the agricultural watersheds under various distinct land management practices. For the present study, a small agricultural watershed has been selected for runoff assessment. Watershed is considered to be the ideal unit for management of the natural resources. Extraction of watershed parameters using Remote Sensing and Geographical Information System (GIS) and use of mathematical models is one of the current trends for hydrologic evaluation of these watersheds monitored. The Soil and Water Assessment Tool (SWAT) having an interface with Quantum GIS (QGIS) software (QSWAT version 1.3) was selected for the estimation of surface runoff from an area of Punpun basin near Patna an intermediate watershed of Punpun river, located in southern Bihar region. Maps of the region obtained from the Bihar Remote Sensing Application Centre (BIRSAC) were used for computation. The model was run and validated with the observed runoff and for the years 2005-2010. The performance of the model was evaluated using statistical and graphical methods to assess the capability of the model in simulating the surface runoff from the study area. According to the model estimates, the value for the surface runoff was maximum for the year 2007 as 710 mm and was minimum for the year 2005 with about 185 mm. As per the observed values of discharge from the Central Water Commission (CWC), the values for surface runoff for these years were different by about 10 to 11%.

Investigating the origin and pathways of atmospheric rivers in the world

Atmospheric rivers (ARs) play an important role in the water cycle and destructive phenomena such as floods and storms. Thus, here the origin, structure, and pathway of ARs in the world were investigated considering the importance of the issue. To this end, the daily wind vector and jet stream data of the ERA-Interim were obtained with 0.25° × 0.25° spatial resolution for 1995–2019. Satellite images of Moderate Resolution Imaging Spectroradiometer (MODIS), Global Precipitation Measurement (GPM), and Geostationary Operational Environmental Satellite (GEOS) Water Vapor were used to examine the amount of precipitation caused by ARs. Also, graphical images were produced to study the origin, pathway, and expansion of ARs. The results indicated that jet streams play a major role in the genesis, direction, and pathway of ARs. Also, high-pressure (low-pressure) centers have a substantial role in the expansion (destination) of ARs. Regions such as west of the USA, west of southern headland of South America, northwest of Europe, the path of northeast Saudi Arabia to northeast Iran, Australia, and the distance between Japan and the east coast of Russia were the most affected regions of precipitation due to ARs. According to the results, there were seven major sources of ARs in the world, of which the most important one was located in southeast Asia. Regarding monthly distribution, January, September, and October had the highest occurrence of ARs. There was a minor difference in the number of ARs in two hemispheres. Only in the southern hemisphere did the ARs have a longer longitude. Investigating the number of occurrences of ARs indicated that in the highest state, three to four ARs were observed in the world simultaneously. Also, more than 90% of the ARs moved through the oceans.

Experimental assessment of short cycling in a hybrid photovoltaic-thermal heat pump system

An experiment is conducted in this paper to analyse the effect of short cycling phenomenon on the performance of a hybrid photovoltaic-thermal heat pump system. The system utilises indirect expansion to cool a photovoltaic-thermal panel through a photovoltaic-thermal water buffer tank that supplies a heat pump, providing space heating using a convection radiator. A photovoltaic-thermal module rated at 200 W electrically and 650 W thermally is generates electricity and absorbs heat to be utilized by a water-to-water heat pump with heating capacity of 7.77 kW. The system was monitored over one-hour operating times for a range of solar irradiances [250–650 W/m2], water flow rates through the photovoltaic-thermal module [7.3 l/min–17.3 l/min] and photovoltaic-thermal buffer tank water volumes [45–75 litres]. Results show the system successfully cools the photovoltaic surface by up to 33 °C. This leads to an electrical efficiency increase of up to 0.7%, correlating to a 17.5% increase in generated electricity. The heat pump experiences coefficient of performance values up to 7. Short cycling frequency increased as the solar irradiance increased. Varying water flow rates through the photovoltaic-thermal module have less influence on system performance than solar irradiance, however, increasing the flow rate from 7.3 l/min to 17.3 l/min results in the photovoltaic surface temperature reducing by 1 °C and short cycling frequency increasing. Variation in the photovoltaic-thermal buffer tank water volume from 45 to 75 litres decreased the photovoltaic surface temperature by 5 °C and increased the short cycling frequency from 6 cycles/hour to 3 cycles/hour.

Business cycles in emerging markets: the role of liability dollarization and valuation effects

Understanding differences in business cycle phenomena between Emerging Market Economies (EMEs) and industrialized countries has been at the center of recent research on macroeconomic fluctuations. The purpose of this paper is to investigate the importance of certain credit market imperfections in different EMEs. To this end, we develop a small open economy Dynamic Stochastic General Equilibrium (DSGE) framework featuring both permanent and transitory productivity shocks, differentiated home and foreign goods, and endogenous exchange rate movements. Furthermore, our model incorporates liability dollarization as a particular form of financial frictions in EMEs. In this vein, we account for the fact that emerging markets traditionally have had difficulties in borrowing in domestic currency on international capital markets and thus allow for valuation effects in our analysis. We estimate our model using Bayesian techniques for a number of EMEs and thereby control for potential heterogeneity across countries. Contrary to previous studies in this strand of the literature, we include a (vector-)autoregressive measurement error component to capture off-model dynamics. Regarding business cycles in emerging markets, our main findings are that (i) even though we incorporate financial frictions in the framework, trend shocks are the main determinant of macroeconomic fluctuations, (ii) accounting for liability dollarization ameliorates the model fit, and (iii) valuation effects on average stabilize changes in the net foreign asset position.

Long-Term Observations of Atmospheric Speciated Mercury at a Coastal Site in the Northern Gulf of Mexico during 2007–2018

Atmospheric mercury species (gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM)), trace pollutants (O3, SO2, CO, NO, NOY, and black carbon), and meteorological parameters have been continuously measured since 2007 at an Atmospheric Mercury Network (AMNet) site that is located on the northern coast of the Gulf of Mexico in Moss Point, Mississippi. For the data that were collected between 2007 and 2018, the average concentrations and standard deviations are 1.39 ± 0.22 ng m−3 for GEM, 5.1 ± 10.2 pg m−3 for GOM, 5.9 ± 13.0 pg m−3 for PBM, and 309 ± 407 ng m−2 wk−1 for mercury wet deposition, with interannual trends of −0.009 ng m−3 yr−1 for GEM, −0.36 pg m−3 yr−1 for GOM, 0.18 pg m−3 yr−1 for PBM, and 2.8 ng m−2 wk−1 yr−1 for mercury wet deposition. The diurnal variation of GEM shows lower concentrations in the early morning due to GEM depletion, likely due to plant uptake in high humidity events and slight elevation during the day, likely due to downward mixing to the surface of higher concentrations of GEM in the air aloft. The seasonal variation of GEM shows higher levels in winter and spring and lower levels in summer and fall. Diurnal variations of both GOM and PBM show broad peaks in the afternoon likely due to the photochemical oxidation of GEM. Seasonally, PBM measurements exhibit higher levels in winter and early spring and lower levels in summer with rising levels in fall, while GOM measurements show high levels in late spring/early summer and late fall and low levels in winter. The seasonal variation of mercury wet deposition shows higher values in summer and lower values in winter, due to larger rainfall amounts in summer than in winter. As expected, anticorrelation between mercury wet deposition and the sum of GOM and PBM, but positive correlation between mercury wet deposition and rainfall were observed. Correlation among GOM, ozone, and SO2 suggests possible different GOM sources: direct emissions and photochemical oxidation of GEM, with the possible influence of boundary layer dynamics and seasonal variability. This study indicates that the monitoring site experiences are impacted from local and regional mercury sources as well as large scale mercury cycling phenomena.

Germination of physically dormant seeds of Colubrina glandulosa Perkins (Rhamnaceae)

This study analyzed morpho-anatomy and histochemistry of seed coats, the effect of temperature on breaking seed dormancy and changes in water gap of Colubrina glandulosa Perkins (Rhamnaceae). Thermal shocks, alternating temperatures and forest environments were tested to analyze the break of physical dormancy. Morpho-anatomical studies were made using fresh or fixed tissue observed under stereoscopic, optical and scanning microscopes. To perform histochemical studies, sections of fresh seeds were left to stain in different reagents and then observed under epifluorescence microscope. Seedling emergence in forest edge and forest understory was similar to seed germination under laboratory conditions, indicating that the differences between environments had no effect on the germination of seeds. The germination ability of fresh seeds was lost in forest gap environments or when stored. Alternating temperature and thermal shocks have not alleviated the physical dormancy of seeds with the exception of dormancy acquired during seed storage. The results of germination suggest the presence of sensitive cycling phenomenon in these seeds. The seed coat features were similar to those of species undergoing physical dormancy, presenting a layer of macrosclereids impregnated with substances impermeable to water, as callose and lignin, in addition to compact sclerenchymatic tissue. Treatments of sulfuric acid and alternating temperatures increased the width and number of cracks around the hilar fissure; however, water could not penetrate the seed through these cracks, suggesting that water enters through the hilar slit.

Optimization analysis of heavy metal pollutants removal from fine-grained soil by freeze-thaw and washing technology

Heavy metal contaminants in clay soils can be removed through freeze–thaw cycles and washing, but the removal efficiency is low. In this study, the cause of low remediation efficiency was analyzed through the influence of eluent concentration and replenishment sequence on the frost heave of soil in combination with one-dimensional freezing soil column experiments. Results showed that the viscosity coefficient of 0.15 mol/L ethylene diamine tetraacetic acid (EDTA) increased by approximately 10% compared with that of deionized water. This condition led to an increase in the migration resistance of the eluent in the soil and a decrease in the liquid–solid ratio, which in turn decreased water absorption by approximately 62% and affected removal efficiency. The pH of the soil column increased by approximately 12.9% compared with the initial value (pH 6.93). Its value was between 7 and 8, which was within the range for conducive crop growth after freeze-thaw cycles and washing. The original structure of soil particles could be destroyed during the freeze-thaw cycles, which contributed to improving washing efficiency. After seven freeze-thaw cycles, the concentrations of the single leachate were 642.3 mg/L of lead (Pb) and 3439 mg/L of cadmium (Cd), and the extraction efficiencies were 77.24% for Pb and 37.78% for Cd. This research provids new methods that utilizes the freeze-thaw cycle phenomenon in nature for the remediation of heavy-metal-contaminated clay soils.

A recurrent neural network approach to predicting hemoglobin trajectories in patients with End-Stage Renal Disease.

The most severe form of kidney disease, End-Stage Renal Disease (ESRD) is treated with various forms of dialysis - artificial blood cleansing. Dialysis patients suffer many health burdens including high mortality and hospitalization rates, and symptomatic anemia: a low red blood cell count as indicated by a low hemoglobin (Hgb) level. ESRD-induced anemia is treated, with variable patient response, by erythropoiesis stimulating agents (ESAs): expensive injectable medications typically administered during dialysis sessions. The dosing protocol is typically a population level protocol based on original clinical trials, the use of which often results in Hgb cycling. This cycling phenomenon occurs primarily due to the mismatch in the time between dosing decisions and the time it takes for the effects of a dosing change to be fully realized. In this paper we develop a recurrent neural network approach that uses historic data together with future ESA and iron dosing data to predict the 1, 2, and 3 month Hgb levels of patients with ESRD-induced anemia. The results of extensive experimentation indicate that this approach generates predictions that are clinically relevant: the mean absolute error of the predictions is comparable to estimates of the intra-individual variability of the laboratory test for Hgb.

Effects of longitudinal vortex generators on the heat transfer deterioration of supercritical CO2 in vertical tubes

In order to improve the safety performance of supercritical heat exchanger, vertical tubes with three kinds of longitudinal vortex generators (LVGs) are numerically investigated to understand the mechanism of mitigation effects on the HTD phenomenon. The results show that the thermal efficiency index η in tube with single-row LVG is increased by 15.2% and the maximum value of wall temperature is decreased by 8.7 K. It is concluded that the mitigation of wall temperature peak benefits from the reduction of the boundary layer thickness and enhancement of flow mixing in the downwash zone. Furthermore, the thermal efficiency index η in tube with single-row LVG is increased by 73.4% and the maximum value of wall temperature is decreased by 67.7 K, which fully demonstrates the potential of LVG for supercritical heat exchanger. When the vortex structure produced by LVG array covers only part of the inner wall, HTD cycles may occur and lead to the decrease of thermal efficiency. On the other hand, HTD cycle phenomenon is eliminated when the inner wall is fully covered by the vortex pairs.

Putting the Cycle Back into Business Cycle Analysis

Are business cycles mainly a response to persistent exogenous shocks, or do they instead reflect a strong endogenous mechanism which produces recurrent boom-bust phenomena? In this paper we present evidence in favor of the second interpretation and we highlight the set of key elements that influence our answer. The elements that tend to favor this type of interpretation of business cycles are (i) slightly extending the frequency window one associates with business cycle phenomena, (ii) allowing for strategic complementarities across agents that arise due to financial frictions, and (iii) allowing for a locally unstable steady state in estimation. (JEL E22, E24, E23, E44)

Power Converters Topological Transformation Using Dual and Isomorphic Principles

In this article, topology transformations of power converters are realized through the dual and isomorphic principles for both the planar and nonplanar circuits. The topology cycling phenomenon is discovered in the topology transformation process and investigated in the power electronics field for the first time. It fills the gap between the dual converter and isomorphic converter and reveals the fundamental relationships among various power converters (existing and/or future ones). By utilizing this new discovery, the operation analysis, modulation/control design, topology derivation can be facilitated in a more comprehensive way. Numerous examples with both theoretical and experimental verifications show the feasibility and versatility of this work.

How interest rate influences a business cycle model

We study the effect of interest rate on phenomenon of business cycle in a Kaldor-Kalecki model. From the information of the People's Bank of China and the Federal Reserve System, we know the interest rate is not a constant but with remarkable periodic volatility. Therefore, we consider periodically forced interest rate in the model and study its dynamics. It is found that, both limit cycle through Hopf bifurcation in unforced system and periodic solutions generated by period doubling bifurcation or resonance in periodically forced system, can lead to cyclical economic fluctuations. Our analysis reveals that the cyclical fluctuation of interest rate is one of a key formation mechanism of business cycle, which agrees well with the pure monetary theory on business cycle. Moreover, this fluctuation can cause chaos in a business cycle system.

A MUSE inquiry into the physical processes taking place within the Abell 2667 Brightest Cluster Galaxy

AbstractBrightest cluster galaxies (BCGs) residing in cool-core clusters are known to be the stage of intricate baryon cycle phenomena (e.g. gas inflows, AGN outflows, star formation feedback). The scenarios describing the observed properties of these galaxies are still controversial, suffering from limitations due to the spatial resolving power of the instruments, specifically for galaxies beyond the Local Universe. However, the dramatic improvements introduced by the integral-field unit instruments (e.g. MUSE) could shed light on the physical processes driving the evolution of these galaxies. We present an extensive analysis of the stellar and gas properties (i.e. kinematics, stellar mass, star formation rate) of the radio-loud BCG sitting at the centre of the X-ray luminous cool-core cluster Abell 2667 (z = 0.23), based on MUSE data. Our results indicate that the BCG is a massive elliptical, hosting an AGN that is possibly undergoing accretion of cold star-forming clouds of ICM or galactic cannibalism.

Analytical solution for post-death transmission model of Ebola epidemics

In this paper, we shall introduce deceased human (D) transmission to the cycle phenomenon of disease modelling, which has a direct relationship with the infective compartment of the stochastic Susceptible-Infected-Recovered (SIR) disease model. Due to this, the noise covariance matrices of the standard stochastic SIR model will be modified. This will be done by using van Kampen's expansion method to approximate the master equation and the stochastic Fokker–Planck equation to analytically calculate a power spectral density (PSD) expression. A vector-valued process is used and shows that the absolute value of the real part of the principal diagonal of the PSD matrix solution is the spectral density of the system which is compared to the average PSD of the stochastic simulations. We aim to investigate the problem of identifiability when deceased humans act as an extended state of host infection using the SIR-D model during Ebola epidemics. Using our analytical solution model, we show that for an increasing degree of transmission parameter values the infected route cannot be identified, whereas the deceased human transmission shows enhancement for the persistence of Ebola virus disease using epidemiology data of the Democratic Republic of Congo.