Linear Relation Research Articles

Overweight, Obesity, and Age Are the Main Determinants of Cardiovascular Risk Aggregation in the Current Mexican Population: The FRIMEX III Study.

Background: The Mexican population exhibits several cardiovascular risk factors (CVRF) including high blood pressure (HBP), dysglycemia, dyslipidemia, overweight, and obesity. This study is an extensive observation of the most important CVFRs in six of the most populated cities in Mexico. Methods: In a cohort of 297,370 participants (54% female, mean age 43 ± 12.6 years), anthropometric (body mass index (BMI)), metabolic (glycemia and total cholesterol (TC)), and blood pressure (BP) data were obtained. Results: From age 40, 40% and 30% of the cohort's participants were overweight or obese, respectively. HBP was found in 27% of participants. However, only 8% of all hypertensive patients were controlled. Fifty percent of the subjects 50 years and older were hypercholesterolemic. Glycemia had a constant linear relation with age. BMI had a linear correlation with SBP, glycemia, and TC, with elevated coefficients in all cases and genders. The β1 coefficient for BMI was more significant in all equations than the other β, indicating that it greatly influences the other CVRFs. Conclusions: TC, glycemia, and SBP, the most critical atherogenic factors, are directly related to BMI.

Textural indices of aerial images reveal urban landscapes temporal dynamics and their effects on plants and birds

Landscape temporal dynamics are a crucial concern in ecology to understand current biodiversity. But historical environmental data are often not easily available. This study assesses for the first time the potential of historical orthophotographs to describe past landscape conditions and determine the temporal lag between landscape changes and biotic communities responses.This method utilizes Gray level Co-occurrence Matrix (GLCM) texture indices computed from black and white orthophotographs to construct continuous metrics of landscape composition. Metrics were first developed using present-day data, i.e. 2015, and calibrated with categorical land cover maps of the Strasbourg Eurometropolis, France. Subsequently, these metrics were applied to historical orthophotographs from 1966, 1976, 1986, and 2000. Plant and bird data from research and citizen science programs were used to estimate the time delay in which these communities respond to evolutions in built areas and high vegetation.Obtained texture-based models reveal that built areas exhibit high contrast and homogeneity, depicted through a linear relation, and that high vegetation display low pixel brightness and high brightness diversity, better described via a nonlinear model. We successfully applied those findings to historical orthophotographs, and revealed dependencies on landscape composition up to 50 years ago for plants and up to 30 years ago for birds, with the time lag and the influence of built and high vegetation areas depending on the selected biodiversity indices.These results demonstrate the utility of archive black and white orthophotographs' texture indices for describing urban landscapes over the past five decades, making them valuable tools for ecological research. These indices are more accessible than categorical data like land cover maps for past years. They have the potential to greatly benefit future studies investigating time lags in landscape ecology, simplifying access to historical landscape features and contributing to sustainable urban planning efforts.

Monotonic and Linear Relations between Growth of Quality vs Growth in Quantity in Open-Source Software Projects

Mathematical models have been developed to study the relation between the growth of quantity and the growth of quality of open-source collaborative software repositories of GitHub. GitHub events triggering the growth of quantity and quality have been identified. Linear regression analysis, Pearson’s, Spearman’s, and Kendall’s correlation coefficients have been used. Hypothesis testing has led to the conclusion that there may be a linear relation between quality and quantity within a certain range of values. Positive monotonic relations and dependency between quantity and quality have been strongly established. Scripts for automated testing have been developed.

Positivity-hardness results on Markov decision processes

This paper investigates a series of optimization problems for one-counter Markov decision processes (MDPs) and integer-weighted MDPs with finite state space. Specifically, it considers problems addressing termination probabilities and expected termination times for one-counter MDPs, as well as satisfaction probabilities of energy objectives, conditional and partial expectations, satisfaction probabilities of constraints on the total accumulated weight, the computation of quantiles for the accumulated weight, and the conditional value-at-risk for accumulated weights for integer-weighted MDPs. Although algorithmic results are available for some special instances, the decidability status of the decision versions of these problems is unknown in general. The paper demonstrates that these optimization problems are inherently mathematically difficult by providing polynomial-time reductions from the Positivity problem for linear recurrence sequences. This problem is a well-known number-theoretic problem whose decidability status has been open for decades and it is known that decidability of the Positivity problem would have far-reaching consequences in analytic number theory. So, the reductions presented in the paper show that an algorithmic solution to any of the investigated problems is not possible without a major breakthrough in analytic number theory. The reductions rely on the construction of MDP-gadgets that encode the initial values and linear recurrence relations of linear recurrence sequences. These gadgets can flexibly be adjusted to prove the various Positivity-hardness results.

University students’ burnout profiles and their relation to creativity and multilingualism

The present study aims to identify burnout profiles among Russian-speaking university students (n = 509) and their relation to creativity and multilingualism. The Maslach Burnout Inventory, Reisman Diagnostic Creativity Assessment, and Multilingual and Multicultural Experience Questionnaire were used to measure burnout, creativity, and language/cultural background, respectively. Five burnout profiles were identified through latent profile analysis, three consistent and two inconsistent. Consistent profiles with similar levels of all burnout dimensions (High, Average, Low burnout) showed a linear relation to creativity: the higher the burnout level, the lower the creativity level was. The inconsistent Cynic-exhausted-efficacious profile demonstrated exceptionally high scores on multilingualism compared to all burnout profiles and creativity scores comparable to low and average burnout profiles. The inconsistent Inefficacious profile was negligibly small compared to those reported in the literature, so no conclusions can be drawn regarding creativity and multilingualism in this profile. The results are considered within the framework of emotional burnout and plurilingual creativity research.

Colored multizeta values in positive characteristic

Abstract In 2004, Thakur introduced a positive characteristic analogue of multizeta values. Later, in 2017, he mentioned the two colored variants which are positive characteristic analogues of colored multizeta values in his survey of multizeta values in positive characteristic. In this paper, we study one of those two variants. We establish their fundamental properties, that include their non-vanishing, sum-shuffle relations, 𝑡-motivic interpretation and linear independence. For the linear independence results, we prove that there are no nontrivial k ̄ \overline{k} -linear relations among the colored multizeta values with different weights.

The Role Of Corporate Social Responsibility On Pakistani CSR Award-Winning Firms And Its Impact On A Firm's Financial Performance

The critical study in vogue spells out the relationship between CSR and an established firm's financial performance. The study sample size is the CSR Award-winning companies of Pakistan. We have scientifically derived this research on CSR activities which are not directly affecting a firm's revenue, sales, operations, etc. The results interpreted that Award-winning-firm policies of CSR received an encouraging impact on Companies' financial performance, productivity, routine operations, and social policies. The contemporary study results invariably find that the best Award-winning CSR company's social legislation properly obtains meaningful contribution on social CSR activities since CSR (-1) merely enjoys a linear relation with CSR.

Two-dimensional time-resolved scintillating sheet monitoring of proton pencil beam scanning FLASH mouse irradiations.

Dosimetry in pre-clinical FLASH studies is essential for understanding the beam delivery conditions that trigger the FLASH effect. Resolving the spatial and temporal characteristics of proton pencil beam scanning (PBS) irradiations with ultra-high dose rates (UHDR) requires a detector with high spatial and temporal resolution. To implement a novel camera-based system for time-resolved two-dimensional (2D) monitoring and apply it in vivo during pre-clinical proton PBS mouse irradiations. Time-resolved 2D beam monitoring was performed with a scintillation imaging system consisting of a 1mm thick transparent scintillating sheet, imaged by a CMOS camera. The sheet was placed in a water bath perpendicular to a horizontal PBS proton beam axis. The scintillation light was reflected through a system of mirrors and captured by the camera with 500 frames per second (fps) for UHDR and 4 fps for conventional dose rates. The raw images were background subtracted, geometrically transformed, flat field corrected, and spatially filtered. The system was used for 2D spot and field profile measurements and compared to radiochromic films. Furthermore, spot positions were measured for UHDR irradiations. The measured spot positions were compared to the planned positions and the relative instantaneous dose rate to equivalent fiber-coupled point scintillator measurements. For in vivo application, the scintillating sheet was placed 1cm upstream the right hind leg of non-anaesthetized mice submerged in the water bath. The mouse leg and sheet were both placed in a 5cm wide spread-out Bragg peak formed from the mono-energetic proton beam by a 2D range modulator. The mouse leg position within the field was identified for both conventional and FLASH irradiations. For the conventional irradiations, the mouse foot position was tracked throughout the beam delivery, which took place through repainting. For FLASH irradiations, the delivered spot positions and relative instantaneous dose rate were measured. The pixel size was 0.1mm for all measurements. The spot and field profiles measured with the scintillating sheet agreed with radiochromic films within 0.4mm. The standard deviation between measured and planned spot positions was 0.26mm and 0.35mm in the horizontal and vertical direction, respectively. The measured relative instantaneous dose rate showed a linear relation with the fiber-coupled scintillator measurements. For in vivo use, the leg position within the field varied between mice, and leg movement up to 3mm was detected during the prolonged conventional irradiations. The scintillation imaging system allowed for monitoring of UHDR proton PBS delivery in vivo with 0.1mm pixel size and 2ms temporal resolution. The feasibility of instantaneous dose rate measurements was demonstrated, and the system was used for validation of the mouse leg position within the field.

A study on the metallicity gradients in the galactic disk using open clusters

We study the metallicity distribution and evolution in the galactic disk based on the largest sample of open star clusters in the galaxy. From the catalog of 1,879 open clusters in the range of galactocentric distance (RGC) from 4 to 20 kpc, we investigate the variation in metallicity in the galactic disk as functions of RGC, vertical distance (Z), and ages of the clusters. In the direction perpendicular to the galactic plane, the variation in metallicity is found to follow a stepped linear relation. We estimate a vertical metallicity gradient d[Fe/H]d|Z| of −0.545 ± 0.046 dex kpc−1 for |Z| < 0.487 kpc and −0.075 ± 0.093 dex kpc−1 for 0.487 < |Z| < 1.8 kpc. On average, metallicity variations above and below the galactic plane are found to change at similar rates. The change in metallicity in the radial direction is also found to follow a two-function linear relation. We obtain a radial metallicity gradient d[Fe/H]dRGC of −0.070 ± 0.002 dex kpc−1 for 4.0 ≲ RGC ≲ 12.8 kpc and −0.005 ± 0.018 dex kpc−1 for 12.8 ≲ RGC ≲ 20.5 kpc, which clearly shows a strong variation in the metallicity gradient when moving from the inner to the outer galactic disk. The age–metallicity relation (AMR) is found to follow a steeper negative slope of −0.031 ± 0.006 dex Gyr−1 for clusters older than 240 Myr; however, there is some hint of positive metallicity age gradient for younger clusters.

Weyl Fermions on a Finite Lattice.

The phenomenon of unpaired Weyl fermions appearing on the sole 2n-dimensional boundary of a (2n+1)-dimensional manifold with massive Dirac fermions was recently analyzed in D. B. Kaplan [preceding Letter, Chiral gauge theory at the boundary between topological phases, Phys. Rev. Lett. 132, 141603 (2024).PRLTAO0031-900710.1103/PhysRevLett.132.141603]. In this Letter, we show that similar unpaired Weyl edge states can be seen on a finite lattice. In particular, we consider the discretized Hamiltonian for a Wilson fermion in (2+1) dimensions with a 1+1 dimensional boundary and continuous time. We demonstrate that the low lying boundary spectrum is indeed Weyl-like: it has a linear dispersion relation and definite chirality and circulates in only one direction around the boundary. We comment on how our results are consistent with Nielsen-Ninomiya theorem. This work removes one potential obstacle facing the program outlined in D. B. Kaplan, preceding Letter, for regulating chiral gauge theories.

Mathematical analysis of left ventricular elastance with respect to afterload change during ejection phase.

Since the left ventricle (LV) has pressure (Plv) and volume (Vlv), we can define LV elastance from the ratio between Plv and Vlv, termed as "instantaneous elastance." On the other hand, end-systolic elastance (Emax) is known to be a good index of LV contractility, which is measured by the slope of several end-systolic Plv-Vlv points obtained by using different loads. The word Emax originates from the assumption that LV elastance increases during the ejection phase and attains its maximum at the end-systole. From this concept, we can define another elastance determined by the slope of isochronous Plv-Vlv points, that is Plv-Vlv points at a certain time after the ejection onset time by using different loads. We refer to this elastance as "load-dependent elastance." To reveal the relation between these two elastances, we used a hemodynamic model that included a detailed ventricular myocyte contraction model. From the simulation results, we found that the isochronous Plv-Vlv points lay in one line and that the line slope corresponding to the load-dependent elastance slightly decreased during the ejection phase, which is quite different from the instantaneous elastance. Subsequently, we analyzed the mechanism determining these elastances from the model equations. We found that instantaneous elastance is directly related to contraction force generated by the ventricular myocyte, but the load-dependent elastance is determined by two factors: one is the transient characteristics of the cardiac cell, i.e., the velocity-dependent force drops characteristics in instantaneous shortening. The other is the force-velocity relation of the cardiac cell. We also found that the linear isochronous pressure-volume relation is based on the approximately linear relation between the time derivative of the cellular contraction force and the cellular shortening velocity that results from the combined characteristics of LV and aortic compliances.

Statistical analysis on branching characteristics of positive streamer discharges in N2–O2 mixtures

Streamers are fast-propagating ionization channels that can usually branch and form complex tree-like structures in dielectric media. In this paper, we perform experiments on positive streamers in different N2–O2 mixtures under varying conditions including voltage, pressure, and electrode geometry, with at least 125 discharge images captured for each condition. We present a statistical analysis on streamer branching characteristics from 3D models that are reconstructed by stereoscopic stroboscopic images and our dedicated semi-automatic 3D reconstruction method.We found that by varying the concentration of O2, the morphology and branching characteristics are greatly changed. Specifically, the average branching angle decrease significantly from 90∘ in air to 66∘ in 1% O2, suggesting that photoionization plays an important role in streamer branching. The branching angles in our work are generally larger than previously reported results due to the resolved 3D structures of discharges by our method. A linear relation between the streamer diameter ratio and the branching direction difference of two daughter branches is found, which intersects the vertical axis almost at unity. It is also found that the average branching angles, streamer velocities and diameters increase as the voltage increases. This is again attributed to stronger photoionization effect under higher voltages. The velocities and diameters are similar at different pressures but at the same reduced electric field. The average branching angle decreases from 90∘ at 133 mbar to 79∘ at 200 mbar. This suggests that stochastic fluctuations become dominant over photoionization effect at higher pressures.

Paraxial and ray approximations of acoustic vortex beams.

A compact analytical solution obtained in the paraxial approximation is used to investigate focused and unfocused vortex beams radiated by a source with a Gaussian amplitude distribution. Comparisons with solutions of the Helmholtz equation are conducted to determine bounds on the parameter space in which the paraxial approximation is accurate. A linear relation is obtained for the dependence of the vortex ring radius on the topological charge, characterized by its orbital number, in the far field of an unfocused beam and in the focal plane of a focused beam. For a focused beam, it is shown that as the orbital number increases, the vortex ring not only increases in radius but also moves out of the focal plane in the direction of the source. For certain parameters, it is demonstrated that with increasing orbital number, the maximum amplitude in a focused beam becomes localized along a spheroidal surface enclosing a shadow zone in the prefocal region. This field structure is described analytically by ray theory developed in the present work, showing that the spheroidal surface in the prefocal region coincides with a simple expression for the coordinates of the caustic surface formed in a focused vortex beam.

Processes explaining increased ocean dynamic sea level in the North Sea in CMIP6

Ocean dynamic sea level (ODSL) is expected to be one of the major contributors to sea level rise in the North Sea during the 21st century. This component is defined as the spatial sea level anomaly due to ocean currents, wind stresses and local thermosteric and halosteric effects. Climate models from CMIP5 and CMIP6 show a large spread, as well as an increase between CMIP5 and CMIP6 North Sea ODSL projections. In this study, we apply linear regression models on CMIP5 and CMIP6 data to get a better understanding of the processes that influence ODSL change in the North Sea. We find that neither global surface air temperature nor global mean thermosteric sea level can reproduce ODSL projections based on a linear relation in CMIP6, whereas this was the case for CMIP5. Including the strength of the Atlantic meridional overturning circulation (AMOC) as an additional predictor enables us to reproduce long-term changes in ODSL for both ensembles. The sensitivity to the AMOC increased in CMIP6, which points to a difference in model dynamics between CMIP5 and CMIP6, and a more important role of the deep ocean. To investigate this further, we analyse mixed layer depth data in the North Atlantic. We find that models with a relatively deep mixed layer in the Greenland Sea over the period 1985–2004, project larger rise in ODSL in the North Sea for both CMIP5 and CMIP6. This implies that the location of deep water formation in the North Atlantic potentially influences ODSL in the North Sea. The number of these models increased from CMIP5 to CMIP6, again pointing to a different sensitivity to larger scale processes, potentially explaining the difference between the two ensembles.

Mechanical behaviors and rupture processes of a typical granitic stratum

Granitic veins (GVs) have a significant influence on the mechanical responses of tunnels excavated in granitic strata. Distinguishing the mechanical properties of host granites (HGs), GVs and vein-granite interfaces (VGIs) is critical. For this, this paper analyzed the mechanical behaviors and rupture processes of typical HG, GV, and VGI samples under uniaxial compression condition. For the rocks studied, although the linear axial stress‒strain relation can be identified and the deformation modulus can be determined, the transverse deformation developed nonlinearly with axial stress. As a result, the instantaneous Poisson's ratio increases continuously and may even exceed 0.5, making it extremely difficult to accurately determine the Poisson's ratio. In addition, the studied GV samples were found to be significantly brittle, indicating that large-scale GVs cannot be ignored when assessing rockburst hazards in granitic strata with brittle GVs. In terms of the rupture process, the HG and GV samples were gradually damaged by the formation of small-scale cracks and then ruptured by large cracks formed from small-scale cracks, whereas the VGI samples ruptured along large cracks with significant energy release. By examining the characteristic stress thresholds of these three granites, it is noted that the crack closure stress σcc exceeds both the crack initiation stress σci and the crack damage stress σcd for the HG and VGI samples. The transverse damage to a tested sample appears to be significantly greater than the axial damage, which is essentially related to the rock grain size and grain size distribution.

Mixing and Combustion of Methane-Oxygen Flame in a Coaxial Dual-Shear Jet Nozzle

In this study, a coaxial dual-shear jet nozzle is designed to enhance mixing and establish stable methane–oxygen combustion. The characteristics of mixing and combustion of methane–oxygen flames are experimentally investigated in nonreacting and reacting cases by varying the outer-to-middle velocity ratio ru from 1.1 to 5.7. In the nonreacting cases, acetone–planar-laser-induced fluorescence technology is applied to experimentally study the mixing behavior near the nozzle exit. Since the coaxial dual-shear configuration generates a sandwich structure, a flow structure near the exit, including three potential cores and three mixing layers, is established. Two mixture fraction fields divided by a critical velocity ratio ruc are observed, in which the stoichiometric contours have different appearances. Based on the mixing characteristics, a mixing model and a linear scaling relation were presented to predict the stoichiometric mixing length in both nonreacting and reacting flows. Besides, the coaxial dual-shear jets yield more compact flames in cases of ru<2.9, while the conventional coaxial jets produce longer flames with yellow tips. This shows the improvement of the coaxial dual-shear nozzle in mixing and combustion efficiency due to the formation of two shear layers near the nozzle exit. Furthermore, the OH* distribution indicates that the coaxial dual-shear flames produce a lower thermal load on the nozzle, preventing the combustor from experiencing the hazards of ablation.

Quasar Winds Caught on Acceleration and Deceleration

We present an observational study of wind acceleration based on four low-ionization broad absorption line (BAL) quasars (J0136, J1238, J1259, and J1344). J0136 and J1344 (group 1) are radio-quiet and show large BAL-velocity shifts as opposed to stable line-locking associated absorption lines (AALs). Notably, J1344 displays a linear relation between BAL-velocity shift and time interval over three consecutive epochs, characteristic of compelling evidence for BAL acceleration. J1238 and J1259 (group 2) exhibit small BAL-velocity shifts along with steep-spectrum, weak radio emission at 3.0 and 1.4 GHz. All four quasars have spectral energy distributions (SEDs) with a peak at λ rest ∼ 10 μm, suggesting a link between the BAL acceleration and hot dust emission. The group-2 quasars are redder than group-1 quasars and have a steeper rise at 1 μm < λ rest < 3 μm in their SEDs. All but J1238 exhibit a steep rise followed by a plateau-like time evolution in BAL-velocity shift. Our investigations, combined with previous studies of BAL acceleration, indicate that (1) the coupling process between the BALs and the interstellar medium (ISM) is one of the major avenues for the origin of quasar reddening and patchy obscuration, (2) AAL outflows are ubiquitous and likely signify large-scale remnants of BAL winds coupled to the ISM, and (3) wind deceleration that is closely linked to the BAL–ISM coupling process may produce weak radio emission in otherwise radio-quiet quasars.

Prediction of the amplitude of solar cycle 25 from the ratio of sunspot number to sunspot-group area, low latitude activity, and 130-year solar cycle

Prediction of the amplitude of solar cycle is important for understanding the mechanism of solar cycle and solar activity influence on space-weather. We analysed the combined data of sunspot groups from Greenwich Photoheliographic Results (GPR) during the period 1874–1976 and Debrecen Photoheliographic Data (DPD) during 1977–2017 and determined the monthly mean, annual mean, and 13-month smoothed monthly mean whole sphere sunspot-group area (WSGA). We also analysed the monthly mean, annual mean, and 13-month smoothed monthly mean version 2 of international sunspot number (SNT) during the period 1874–2017. We fitted the annual mean WSGA and SNT data during each of Solar Cycles 12–24 separately to the linear and nonlinear (parabola) forms. In the cases of Solar Cycles 14, 17, and 24 the nonlinear fits are found better than the linear fits. We find that there exists a secular decreasing trend in the slope of the WSGA–SNT linear relation during Solar Cycles 12–24. A secular decreasing trend is also seen in the coefficient of the first order term of the nonlinear relation. The existence of ≈77-year variation is clearly seen in the ratio of the amplitude to WSGA at the maximum epoch of solar cycle. From the pattern of this long-term variation of the ratio we inferred that Solar Cycle 25 will be larger than both Solar Cycles 24 and 26. Using an our earlier method (now slightly revised), i.e. using high correlations of the amplitude of a solar cycle with the sums of the areas of sunspot groups in 0–10° latitude intervals of the northern hemisphere during 3.75-year interval around the minimum–and the southern hemisphere during 0.4-year interval near the maximum–of the corresponding preceding solar cycle, we predicted 127±26 and 141±19 for the amplitude of Solar Cycle 25, respectively. Based on ≈130-year periodicity found in the cycle-to-cycle variation of the amplitudes of Solar Cycles 12–24 we find the shape of Solar Cycle 25 would be similar to that of Solar Cycle 13 and predicted for Solar Cycle 25 the amplitude 135±8, maximum epoch 2024.21 (March 2024)±6-month, and the following minimum epoch 2032.21 (March 2032)±6-month with SNT≈4.

Impact of Organic Carbons Addition on the Enrichment Culture of Nitrifying Biofloc from Aquaculture Water: Process, Efficiency, and Microbial Community.

In this study, we developed a rapid and effective method for enriching the culture of nitrifying bioflocs (NBF) from aquacultural brackish water. The self-designed mixotrophic mediums with a single or mixed addition of sodium acetate, sodium citrate, and sucrose were used to investigate the enrichment process and nitrification efficiency of NBF in small-scale reactors. The results showed that NBF with an MLVSSs from 1170.4 mg L-1 to 2588.0 mg L-1 were successfully enriched in a period of less than 16 days. The citrate group performed the fastest enrichment time of 10 days, while the sucrose group had the highest biomass of 2588.0 ± 384.7 mg L-1. In situ testing showed that the highest nitrification efficiency was achieved in the citrate group, with an ammonia oxidation rate of 1.45 ± 0.34 mg N L-1 h-1, a net nitrification rate of 2.02 ± 0.20 mg N L-1 h-1, and a specific nitrification rate of 0.72 ± 0.14 mg N g-1 h-1. Metagenomic sequencing revealed that Nitrosomonas (0.0~1.0%) and Nitrobacter (10.1~26.5%) were dominant genera for AOB and NOB, respectively, both of which had the highest relative abundances in the citrate group. Linear regression analysis further demonstrated significantly positive linear relations between nitrification efficiencies and nitrifying bacterial genera and gene abundance in NBF. The results of this study provide an efficient enrichment culture method of NBF for the operation of biofloc technology aquaculture systems, which will further promote its wide application in modern intensive aquaculture.

Iron-driven self-assembly of dopamine into dumbbell-shaped nanozyme for visual and rapid detection of norfloxacin on a smartphone-assisted platform

Antibiotics in aquatic environments raise health concerns. Therefore, the rapid, on-site, and accurate detection of antibiotic residues is crucial for protecting the environment and human health. Herein, a dumbbell-shaped iron (Fe3+)-dopamine coordination nanozyme (Fe-DCzyme) was developed via an iron-driven self-assembly strategy. It exhibited excellent peroxidase-like activity, which can be quenched by adding l-cysteine to prevent Fe3+/Fe2+ electron transfer but restored by adding norfloxacin. Given the ‘On-Off-On’ effect of peroxidase-like activity, Fe-DCzyme was used as a colourimetric sensor for norfloxacin detection, and showed a wide linear range from 0.05 to 6.00 μM (R2 = 0.9950) and LOD of 27.0 nM. A portable smartphone-assisted detection platform using Fe-DCzyme was also designed to convert norfloxacin-induced color changes into RGB values as well as to realise the rapid, on-site and quantitative detection of norfloxacin. A good linear relation (0.10–6.00 μM) and high sensitivity (LOD = 79.3 nM) were achieved for the smartphone-assisted Fe-DCzyme detection platform. Its application was verified using norfloxacin spiking methods with satisfactory recoveries (92.66%–119.65%). Therefore, the portable smartphone-assisted Fe-DCzyme detection platform with low cost and easy operation can be used for the rapid, on-site and visual quantitative detection of antibiotic residues in water samples.