Maximum Velocity Research Articles

Relative Acceleration and Maximum Velocity in Rugby Players According to Age Category and Playing Position.

Zabaloy, S, Freitas, TT, Alcaraz, PE, Gálvez-González, J, Pereira, LA, Comyns, T, Loturco, I, and Healy, R. Relative acceleration and maximum velocity in rugby players according to age category and playing position. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to: (a) assess the intrasession reliability of the acceleration time constant (i.e., τ) and τ-derived measures; (b) analyze the influence of τ and maximum velocity (Vmax) on 40-m sprint performance and to compare various sprint-related outcomes among rugby players from different playing positions and age categories; and (c) explore the associations between τ and several sprint performance metrics. A total of 300 male rugby players volunteered to participate in this study and were divided into age categories (i.e., under-14 [U14]: n = 91, age: 12.6 ± 0.5 years; under-16 [U16]: n = 85, age: 14.8 ± 0.5 years; under-18 [U18]: n = 75, age: 16.6 ± 0.5 years; and Seniors: n = 49, age: 24.2 ± 4.1 years). The results demonstrated good to excellent reliability for all measured parameters (intraclass correlation coefficient >0.75 and coefficient of variation <9.0%). Younger players (i.e., U14 and U16) displayed lower τ values (effect size: moderate to large; p < 0.02) compared with their older peers (i.e., U18 and Seniors), regardless of their playing position. Moreover, τ was associated with sprint performance metrics at varying levels of correlations (Rho: small to almost perfect; p < 0.001). In conclusion, younger players exhibited lower τ values than their older counterparts, irrespective of their playing positions. The model employed in this study demonstrated its accuracy in assessing several key sprint performance metrics, offering insights that can enhance sprint training programs for rugby players, which can be based on the associations observed among these different variables.

Decoupling the influences of chiral damping and Dzyaloshinskii-Moriya interaction in chiral magnetic domain walls

We revisit the nature and impact of both the chiral damping (CD) and Dzyaloshinskii-Moriya interaction (DMI) in uniaxial chiral ferromagnetic nanowires with broken inversion symmetry. We propose that CD, akin to its chiral energy counterpart (DMI), can be described in terms of the Lifshitz invariants permissible by the underlying symmetry of the system. This representation offers a clearer foundation for integrating CD into the dynamics of various chiral magnetic textures. We theoretically investigate the current-induced motion of chiral domain walls (DWs), driven by both spin-transfer torque and the spin Hall effect in the presence of CD. We demonstrate that it is possible to unambiguously separate the influence of CD from that of DMI by analyzing the current-induced dynamics. In particular, below the Walker breakdown (WB), the DMI does not affect the DW velocity, whereas increases in the strength of CD result in a decrease in the DW velocity. Moreover, for the spin-orbit torque driven motion, while the DMI enhances both the WB current density and the maximum attainable velocity below the WB, the CD only enhances the WB without affecting the maximum attainable velocity below the WB. Our findings open up intriguing opportunities for exploitation in exotic magnetic textures. Published by the American Physical Society 2024

In Vitro Ciclopirox Glucuronidation in Liver Microsomes from Humans and Various Experimental Animals.

Ciclopirox is a widely used antifungal drug, redisposition of which has drawn increasing attentions due to multiple promising activities. The drug undergoes extensive glucuronidation, which acts as a major obstacle in the ongoing novel application and still remains poorly understood. The current study aims to phenotype ciclopirox glucuronidation pathway and as well to decipher the related species differences. Ciclopirox glucuronidation was investigated in liver microsomes from humans (HLM) and various experimental animals. Assays with recombinant uridine diphosphate glucuronosyltransferases (UGTs), enzyme kinetic analyses and selective inhibitors were used to determine the role of individual UGTs in ciclopirox glucuronidation. HLM is highly active in ciclopirox glucuronidation withMichaelis-Menten constant (Km),maximum velocity (Vmax), and intrinsic clearance (CLint)values of 139 μM, 7.89 nmol/min/mg, and 56 μL/min/mg, respectively. UGT1A9 displays by far the highest activity, whereas several other isoforms (UGT1A6, UGT1A7, and UGT1A8) catalyze formation of traced glucuronides. Further kinetic analysis demonstrates that UGT1A9 has a closed Km value (167 μM) to HLM. UGT1A9 selective inhibitor (magnolol) can potently inhibit ciclopirox glucuronidation in HLM with the IC50 value of 0.12 μM. The reaction displays remarkable differences across liver microsomes from mice, rats, cynomolgus monkey, minipig, and beagle dog, with the CLint values in the range of 26-369 μL/min/mg. In addition, ciclopirox glucuronidation activities of experimental animals' liver microsomes were less sensitive to magnolol than that of HLM. Ciclopirox glucuronidation displays remarkable species differences with UGT1A9 as a dominant contributor in humans. It is suggested that the pharmacological or toxicological effects ofciclopirox may be UGT1A9 and species dependent.

Effects of Age and Sex on the Kinematics of the Sprinting Technique in the Maximum Velocity Phase

Effects of Age and Sex on the Kinematics of the Sprinting Technique in the Maximum Velocity Phase

The effect of friction characteristics on electromagnetic impact deformation mechanism of 2A10 aluminum alloy bars

Purpose The purpose objective of this study is to identify the friction coefficient and friction effect in electromagnetic upsetting (EMU) high-speed forming process. Design/methodology/approach Based on numerical simulation and upsetting experiment of 2A10 aluminum alloy bar, the friction coefficient between contact surfaces is obtained by combining the fitting displacement distribution function and the electromagnetic-mechanical coupling numerical model, and the influence of friction effect is analyzed. Findings The maximum impact velocity and acceleration during EMU are 13.9 m/s and −3.3 × 106 m/s2, respectively, and the maximum strain rate is 7700 s−1. The functional distribution relationship between friction coefficient combination (FS, FD) and characteristic parameters [upper diameter (D1) and middle diameter (D2)] is established. The values of FS and FD are 0.1402 and 0.0931, respectively, and the maximum relative error is 2.39%. By analyzing the distribution of equivalent stress and strain, it is found that plastic deformation has obvious zoning characteristics and there is serious failure concentration in the strong shear zone. Originality/value Friction coefficient significantly affects stress or strain distributions in material forming process, but it is difficult to obtain friction coefficients through experimental tests in the high-speed forming process. In this paper, a multi-field coupling numerical model is proposed to determine friction coefficients and applied to the electromagnetic impact loading process (a high-speed forming process). Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0154/

Numerical analysis of blood flow in the abdominal aorta under simulated weightlessness and earth conditions

Blood flow through the abdominal aorta and iliac arteries is a crucial area of research in hemodynamics and cardiovascular diseases. To get in to the problem, this study presents detailed analyses of blood flow through the abdominal aorta, together with left and right iliac arteries, under Earth gravity and weightless conditions, both at the rest stage, and during physical activity. The analysis were conducted using ANSYS Fluent software. The results indicate, that there is significantly less variation in blood flow velocity under weightless conditions, compared to measurement taken under Earth Gravity conditions. Study presents, that the maximum and minimum blood flow velocities decrease and increase, respectively, under weightless conditions. Our model for the left iliac artery revealed higher blood flow velocities during the peak of the systolic phase (systole) and lower velocities during the early diastolic phase (diastole). Furthermore, we analyzed the shear stress of the vessel wall and the mean shear stress over time. Additionally, the distribution of oscillatory shear rate, commonly used in hemodynamic analyses, was examined to assess the effects of blood flow on the blood vessels. Countermeasures to mitigate the negative effects of weightlessness on astronauts health are discussed, including exercises performed on the equipment aboard the space station. These exercises aim to maintain optimal blood flow, prevent the formation of atherosclerotic plaques, and reduce the risk of cardiovascular complications.

The effect of friction characteristics on electromagnetic impact deformation mechanism of 2A10 aluminum alloy bars

Purpose The purpose objective of this study is to identify the friction coefficient and friction effect in electromagnetic upsetting (EMU) high-speed forming process. Design/methodology/approach Based on numerical simulation and upsetting experiment of 2A10 aluminum alloy bar, the friction coefficient between contact surfaces is obtained by combining the fitting displacement distribution function and the electromagnetic-mechanical coupling numerical model, and the influence of friction effect is analyzed. Findings The maximum impact velocity and acceleration during EMU are 13.9 m/s and −3.3 × 106 m/s2, respectively, and the maximum strain rate is 7700 s−1. The functional distribution relationship between friction coefficient combination (FS, FD) and characteristic parameters [upper diameter (D1) and middle diameter (D2)] is established. The values of FS and FD are 0.1402 and 0.0931, respectively, and the maximum relative error is 2.39%. By analyzing the distribution of equivalent stress and strain, it is found that plastic deformation has obvious zoning characteristics and there is serious failure concentration in the strong shear zone. Originality/value Friction coefficient significantly affects stress or strain distributions in material forming process, but it is difficult to obtain friction coefficients through experimental tests in the high-speed forming process. In this paper, a multi-field coupling numerical model is proposed to determine friction coefficients and applied to the electromagnetic impact loading process (a high-speed forming process). Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0154/

A numerical inquiry of the MHD radiative thin film nanofluid flow and heat transfer augmentation for Ni and Ta nanoparticles of different shapes dispersed in C 12 H 26–C 15 H 32 over an unsteady, curved stretching surface

Thin films are a versatile technology used in various industries, including light-emitting diodes, magnetic recording media, electronic device manufacturing, and optical coating. They are crucial for studying quantum phenomena, superlattices, and multiferroic materials. Their small size allows for better thermal transport studies due to the combination of thin film flow and nanoparticles. Therefore, this study aims to investigate thin film flow and heat transfer with the effects of thermal radiations, magnetic field, and velocity slip in association with tantalum ( Ta ) and nickel ( Ni ) nanoparticles that emerged in kerosene oil ( C 12 H 26 − C 15 H 32 ) toward a curved stretching surface. A review of the pertinent literature indicates that no research has previously been done on the present problem of an unsteady thin film flow across a curved stretching surface. The problem under consideration is modeled by choosing the curvilinear coordinate system. The controlling nonlinear system of partial differential equations is transformed into the system of ordinary differential equations by using an appropriate similarity transformation and then solved numerically using the BVP 4 C technique in MATLAB . The impact of significant physical parameters on velocity, temperature, skin friction, and Nusselt numbers are depicted through graphs and radar charts. The investigation highlights the significant influence of magnetohydrodynamics ( MHD ) , thermal radiation, volumetric fraction, and velocity slip on the enhancement of nanofluid temperature. It is also noted that cylindrical-shaped Ta nanoparticles exhibited the maximum velocity, while blade-shaped Ni nanoparticles showed the lowest. Moreover, the maximum and minimum temperatures were observed for blade-shaped Ni nanoparticles and cylindrical Ta nanoparticles, respectively. Additionally, the maximum and minimum values of skin friction are found for cylindrical Ni nanoparticles and blade-shaped Ta nanoparticles, respectively. Similarly, the maximum and minimum Nusselt numbers are recorded for cylindrical Ta nanoparticles and blade-shaped Ni nanoparticles, respectively.

Effect of warm-up protocols using lower and higher loads on multiple-set back squat volume-load

Background The present study aimed to investigate the effects of post-activation performance enhancement (PAPE) after three warm-up protocols on back squat performance in trained men. Methods Fourteen resistance-trained men performed conditioning activity (CA) with high-load (HL-CA), low-load (LL-CA), or usual specific warm-up as a control (CON). HL-CA consisted of one set of three repetitions with 90% of one repetition maximum (RM); LL-CA consisted of one set of six repetitions with 45% of 1 RM performed at maximal velocity; CON involved eight repetitions with 45% of 1 RM at controlled velocity. The participant’s performance was measured using the total number of repetitions and volume load (reps × load × sets). Results There were no significant differences between warm-up for the total number of repetitions (p = 0.17) or total volume load (p = 0.15). There was no difference between conditions for the number of repetitions (main condition effect; p = 0.17); however, participants achieved a significantly higher volume load after HL-PAPE than after CON for the first set (p = 0.04). Conclusion High or low equated-load CA used as warm-up strategies did not potentiate subsequent performance enhancement in multiple-set back squat exercise performed until muscle failure in comparison with usual warm-up.

Effect of warm-up protocols using lower and higher loads on multiple-set back squat volume-load.

The present study aimed to investigate the effects of post-activation performance enhancement (PAPE) after three warm-up protocols on back squat performance in trained men. Fourteen resistance-trained men performed conditioning activity (CA) with high-load (HL-CA), low-load (LL-CA), or usual specific warm-up as a control (CON). HL-CA consisted of one set of three repetitions with 90% of one repetition maximum (RM); LL-CA consisted of one set of six repetitions with 45% of 1 RM performed at maximal velocity; CON involved eight repetitions with 45% of 1 RM at controlled velocity. The participant's performance was measured using the total number of repetitions and volume load (reps × load × sets). There were no significant differences between warm-up for the total number of repetitions (p = 0.17) or total volume load (p = 0.15). There was no difference between conditions for the number of repetitions (main condition effect; p = 0.17); however, participants achieved a significantly higher volume load after HL-PAPE than after CON for the first set (p = 0.04). High or low equated-load CA used as warm-up strategies did not potentiate subsequent performance enhancement in multiple-set back squat exercise performed until muscle failure in comparison with usual warm-up.

An Experimental Investigation Of Local Thermo-Fluidic Heat Transfer In A U-Shaped Mini-Channel Sink

This study investigates experimentally a heated U-shaped mini-channel heat sink using Infrared Thermography and Particle Image Velocimetry for a water coolant flow of Reynolds numbers of 280, 650, and 1350 (based on the hydraulic channel diameter). The choice of this cell geometry is based on its role as a simplified unit of a serpentine heat exchanger, which is proved to be one of the most promising for cooling processes. The use of the infrared camera allows the detection of temperature fields on top of the external surface of the cell. Therefore, aiming to derive the temperature distribution on the channel roof, a dedicated transfer function is implemented. Moreover, we employed the lumped capacitance model for thermal analysis on both infrared measurements and thermocouple data. The latter are recorded to capture the cooling process of the aluminium base and water temperature at the end of the outlet tube. As a result, thermal transient rate, cooling magnitude and equilibrium temperature are obtained. These parameters indicate that higher Reynolds numbers correspond to increased thermal transient rates, enhanced cooling effects, and lower equilibrium temperatures. A non-uniform distribution of heat transfer along the channel is reported, with the most efficient cooling area localized close to the first 90-degree corner. These findings are consistent with numerical simulations and previous experimental observations. PIV results reveal the presence of two fluid acceleration zones following both 90-degree corners, which contribute to improve the water cooling ability in their respective regions. Additionally, the formation of two recirculating bubbles is reported at the inner wall from corners vertices, whose intensity is dependent on Reynolds number, pushing the main flow towards the outer channel wall and reducing the local heat transfer. Turbulent kinetic energy distributions are also investigated, pointing out the presence of intense areas that better match with regions of minimum equilibrium temperature than maximum velocity zones. This suggests the presence of local turbulent unsteadiness and three-dimensional phenomena, which contributes significantly to cooling enhancement.

Gas and water migration in cement slurries at different curing times

Gas and water migration in the hydrating cement slurry is a major cause of well completion failure. Gas and water migration may occur at different curing times due to varying well conditions and cement slurries. The current study has not been carried out to investigate the gas and water migration at different curing times. In this paper, theoretical calculations and migration experiments are used to investigate the gas and water migration in cement slurry at different curing times. The gas and water migration process can be divided into the formation rock to annular cement slurry (F-A) stage and the bottom to top (B-T) stage. At relatively short curing time, the cement slurry is more like a viscous fluid and there is clear interface between the gas and slurry. The pressure difference required for gas migration in F-A stage is very small. Maximum velocity of gas bubble migration in B-T stage is closely related to gas bubble size and cement viscosity. The smaller the size of gas bubble and the greater the viscosity of the cement slurry, the smaller the maximum velocity of the gas bubble will be. There is no clear interface between the water and slurry at relatively short curing time. The pressure difference of water migration is small. At relatively long curing time, the cement slurry has a certain of gel strength and there is also clear interface between the gas/water and slurry. The water migration is similar to gas migration. The pressure difference required for gas and water migration in F-A stage increases as the static gel strength increases. The size of the gas and water bubbles formed after invasion increases as the static gel strength increases. The critical radius at which gas and water bubbles can move is closely related to the static gel strength of the cement slurry. The greater the static gel strength, the larger the critical radius will be. The channeling path sizes of the gas and water migration are all small at relatively short curing times. The dimensions of the channel are gradually increasing from bottom to top. The pressure difference of gas migration and the dimension of channel increase as curing time increases. When the cement slurry cures for a long enough period, the gas cannot migrate in the cement slurry, but only along the weak cement slurry-wellbore interface.

Ergogenic response to caffeine in resistance performance, perceived pain, and female sex hormones following muscular endurance in strength-trained eumenorrheic females during early follicular phase

This study investigates the ergogenic response to caffeine, in terms of repetitions to failure, time under tension, perceived pain, and female sex hormones (oestradiol and progesterone), following muscular endurance during the early follicular phase. Eleven strength-trained eumenorrheic females performed two consecutive trials (48 h apart). Using a double-blind crossover design, participants were randomly assigned to receive either caffeine (4 mg/kg) 1 h before exercise or a placebo. In each trial, participants performed as many repetitions of leg extension and hip adduction as possible at 65% of 1-RM. Two minutes of recovery were allocated between each exercise. Each repetition was performed at maximal velocity. Perceived pain was rated on an 11-point scale immediately after each exercise, and blood samples were drawn from each participant 30 min after completing the test. Data revealed a significant ergogenic response to caffeine in repetitions to failure for leg extension and hip adduction (p = .003 and p = .043, respectively); meanwhile, caffeine led to a significantly longer time under tension in leg extension (p = .001), with no differences in hip adduction (p = .053). In terms of perceived pain, no differences between trials were found for hip adduction (p = .724), but it was rated higher after leg extension in the caffeine trial, when compared to the placebo (p = .011). No differences were observed between trials regarding oestradiol and progesterone levels (p = .138 and p = .350, respectively). In conclusion, ingestion of 4 mg/kg of caffeine increased leg extension and hip adduction repetitions to failure, without main effects on perceived pain and sex hormones, in strength-trained eumenorrheic females during the early follicular phase.

Recent Advances and Perspectives on Food-Grade Immobilisation Systems for Enzymes.

The use of enzyme immobilisation is becoming increasingly popular in beverage processing, as this method offers significant advantages, such as enhanced enzyme performance and expanded applications, while allowing for easy process termination via simple filtration. This literature review analysed approximately 120 articles, published on the Web of Science between 2000 and 2023, focused on enzyme immobilisation systems for beverage processing applications. The impact of immobilisation on enzymatic activity, including the effects on the chemical and kinetic properties, recyclability, and feasibility in continuous processes, was evaluated. Applications of these systems to beverage production, such as wine, beer, fruit juices, milk, and plant-based beverages, were examined. The immobilisation process effectively enhanced the pH and thermal stability but caused negative impacts on the kinetic properties by reducing the maximum velocity and Michaelis-Menten constant. However, it allowed for multiple reuses and facilitated continuous flow processes. The encapsulation also allowed for easy process control by simplifying the removal of the enzymes from the beverages via simple filtration, negating the need for expensive heat treatments, which could result in product quality losses.

The height ratio effects on the flow characteristics of a wall-mounted hemisphere immersed in the turbulent boundary layer

The effects of the height ratios on the flow characteristics of a wall-mounted hemisphere immersed in the turbulent boundary layer are investigated by particle image velocimetry technology (PIV). The Reynolds number based on the hemisphere diameter D is ReD=8160, and three height ratios (i.e., H/D=0.5, 0.4 and 0.3) are selected for comparison at δ/D=0.79, where δ is boundary layer thickness without the presence of hemisphere. The PIV measurements are carried out in x-y plane and x-z plane, and the flow characteristics behind the hemisphere and the distributions of the von Kármán vortices (vK vortices) are investigated. In x-y plane, the curl of the shear layer on the top of the hemisphere brings reverse flow of fluids, and the area of the recirculation region and the area fluctuations are decreased as H/D decreases from 0.5 to 0.3. In x-z plane, the recirculation regions are symmetrical about z/D=0, reflecting reverse flow of fluids induced by the curl of the shear layers on both sides of the hemisphere. Moreover, the maximal velocity deficit is decreased as H/D decreases in x-z plane. The vK vortices are formed from the shear layers on both sides of the hemisphere, and the formation frequencies are same for different H/D, and the value is about 0.35 Hz. The Strouhal number St of the vK vortex is calculated by the hemisphere base diameter, and St slightly decreases from 0.154 to 0.142 as H/D decreases from 0.5 to 0.3. The turbulent fluctuations behind the hemisphere are decreased as H/D decreases.

Present‐Day Three‐Dimensional Crustal Deformation Velocity of the Tibetan Plateau Due to Multi‐Component Land Water Loading

AbstractQuantitative understanding of the land water loading is a prerequisite to the construction of reliable tectonic deformation velocity field in the Tibetan Plateau (TP). Here, for the first time, we image the three‐dimensional crustal loading deformation velocity field of each land water component in the TP. Our results reveal that the loading signal strength of the six land water components ranks from largest to smallest as groundwater, glacier, lake, soil water, permafrost, and snow, with the maximum vertical velocity close to ±1.60 mm/yr and the maximum horizontal velocity exceeding 0.40 mm/yr. All land water components can achieve a strong enough vertical loading velocity exceeding the present‐day Global Positioning System (GPS) velocity at some sites. But for horizontal loading, apparent impacts are only from glacier, lake and groundwater, however, are very limited, with the absolute ratio of loading velocity to GPS velocity being smaller than 5% at almost all the sites.

Flow dynamics and heat transfer in the wake of an rotary oscillating circular cylinder with an isothermal control plate

This research explores the flow dynamics and heat transfer within the wake of a rotary oscillating circular cylinder in the presence of an isothermal control plate. Two-dimensional, unsteady, viscous and laminar flow of a Newtonian fluid is considered using the Higher Order Compact Scheme (HOC) to discretize the governing equations and the Bi-Conjugate Gradient Stabilized method to solve the resulting system. Simulations are performed for various gap ratios, maximum angular velocities, and frequency ratios of oscillation at Prandtl number 0.7 and Reynolds number 150 using an in-house code. Results show a significant increase in heat transmission for d / R 0 = 0.5 and f / f 0 = 0.5 for all αm . Drag and lift coefficients are also analyzed, with the maximum peak of the drag coefficient decreasing by 9.88% for d / R 0 = 3 . This research offers valuable insights for advancing and optimizing aerodynamic forces and heat transfer processes, particularly in the field of fluid dynamics. The study focuses on enhancing the efficiency of heat transfer mechanisms around rotary oscillating circular cylinders, contributing to the development of cutting-edge technologies in aerodynamics and thermal management.

Characteristics of surface flow field and substrate in the spawning ground of Schizothorax grahami

The Spawning ground is a crucial habitat for fish, and the physical characteristics of the habitat are important for fish life history. In this paper, Large-Scale Particle Image Velocimetry (LSPIV) was used to measure the surface flow field and the substrate (particle size and mineral composition) in the spawning ground of Schizothorax grahami. Based on the literature and consideration of experimental feasibility, two spawning grounds in the source of the Chishui River were selected—Erlongqiangbao (located in the mainstream) and Bamaoba (located in the tributary), two and three cross sections of each river section were analyzed respectively. The results show that Erlongqiangbao first flows in the direction of “southeast-northwest” and then “southwest—northeast” after crossing the bridge; the maximum velocity of the reach is 3.374m/s. The size of the substrate is mainly less than 1mm in the upstream section of Erlongqiangbao, both 25-50mm in the middle and downstream, and the substrate type mainly is quartz and calcite; Gushangtian flows in the direction of “southwest-northeast,” the maximum velocity of the reach is 1.537m/s, the size of the substrate is mainly greater than 50mm in the upstream, and 25-50mm in the middle and downstream, the substrate type mainly is quartz, calcite, and dolomite. The mineral compositions of the two spawning sites were analyzed by principal component analysis. Quartz and anorthose are more than 1 in composite scores, respectively ranked first and second, indicating that they play a dominant role in the mineral composition. This study could provide basic data and ideas for restoring S. grahami spawning ground.

Decay Timescales of Chromospheric Condensations in Solar Flare Footpoints

Chromospheric condensations (CCs) are a prominent feature of flare footpoint heating in the solar flare standard model, yet their timescales and velocities are not well understood. Fisher derived several important analytical relationships, which have rarely been examined with modern spectral observations. The Interface Region Imaging Spectrograph (IRIS) provides a wealth of flare data with a high enough cadence to sufficiently capture CC evolution. We analyzed Doppler shifts in Mg ii 2791 and Fe ii 2814 from a sample of flare footpoint pixels observed by IRIS to compare with Fisher's analytics and recent flare models. We found a detection lifetime of 1 minute occurs in 50% of the sample, with Mg ii showing several pixels with longer values and Fe ii almost categorically shorter, and both growing with the maximum velocity, v max. The shifts’ half-life is commonly <40 s and is inversely related to v max, indicating that the first half of the CC evolution has more efficient kinetic energy loss. The lifetime’s wide range and growth with v max indicate that the footpoint atmospherics and heating scenarios can vary more widely than first postulated in Fisher. Around 90% of the sample had observable acceleration periods, lasting an average of 38 and 32 s for Mg ii and Fe ii, respectively. These acceleration periods, as well as serving as flare model diagnostics themselves, could potentially be used to calculate other model diagnostics such as the initially accelerated mass.

Distinct regions of its first intracellular loop contribute to the proper localization, transport activity and substrate-affinity adjustment of the main yeast K+ importer Trk1

Trk1 is the main K+ importer of Saccharomyces cerevisiae. Its proper functioning enables yeast cells to grow in environments with micromolar amounts of K+. Although the structure of Trk1 has not been experimentally determined, the transporter is predicted to be composed of four MPM (transmembrane segment – pore loop – transmembrane segment) motifs which are connected by intracellular loops. Of those, in particular the first loop (IL1) is unique in its length; it forms more than half of the entire protein. The deletion of the majority of IL1 does not abolish the transport activity of Trk1. However IL1 is thought to be involved in the modulation of the transporter's functioning. In this work, we prepared a series of internally shortened versions of Trk1 that lacked various parts of IL1, and we studied their properties in S. cerevisiae cells without chromosomal copies of TRK genes. Using this approach, we were able to determine that both N- and C-border regions of IL1 are necessary for the proper localization of Trk1. Moreover, the N-border part of IL1 is also important for the functioning of Trk1, as its absence resulted in a decrease in the transporter's substrate affinity. In addition, in the internal part of IL1, we newly identified a stretch of amino-acid residues that are indispensable for retaining the transporter's maximum velocity, and another region whose deletion affected the ability of Trk1 to adjust its affinity in response to external levels of K+.