Lighter Loads Research Articles

Review of the biological aspects in the periodontal ligament and alveolar bone associated with compression

Background: Tissue remodeling requires protein degradation through a process directly dependent on metalloproteinases — enzymes capable of degrading the majority of proteins in this system. This process is regulated by some enzyme inhibitors, and balance between enzyme and inhibitor activity is fundamental to tissue integrity and health. Bone resorption and formation, and the molecules involved in these processes, raise questions on possible differences in tissue behavior in the system. Histological studies of tissues surrounding teeth that have been subjected to such forces show the presence of tension (associated with bone formation) and compression, which induce bone resorption. The duration of load application is an important parameterin osteoclastogenesis. The present study aimed to analyze the biological aspects associated with in vitro compression of the PL and alveolar bone. To this end, we reviewed articles describing the biological events that occur in the PL and alveolar bone during load application on this system and the possible influence of culture medium on the expression of molecules involved in response to such an event.
 Methods: This literature review included articles published between March 2008 and January 2018 describing in vitro laboratory tests and data on load application and its associated biological events in the human PL and alveolar bone, including studies on molecular-expression events and pathways involved in the process.
 Conclusions: Intermittent compressive forces stimulate bone resorption in orthodontic treatment, while cyclical forces induce cellular apoptosis at lighter loads than do compressive forces. Both 2D and 3D cell-culture systems seem to reproduce the physiology of evaluated tissues and are reliable analytical models for research purposes.

Contribution of prostaglandins to exercise hyperaemia: workload, ethnicity and sex matter!

The contribution of prostaglandins (PGs) to exercise hyperaemia is controversial. In this review, we argue this is partly explained by differences in exercise intensity between studies. The effects of cyclooxygenase (COX) inhibition and PG assays indicate that PGs contribute more at moderate to heavy than at light workloads and are mainly released by low tissue O2 . But, the release and actions of PGs also depend on other O2 -dependent dilators including ATP, adenosine and NO. K+ may inhibit the action of PGs and other mediators by causing hyperpolarization, but contributes to the hyperaemia. Thus, at lighter loads, the influence of PGs may be blunted by K+ , while COX inhibition leads to compensatory increases in other O2 -dependent dilators. In addition, we show that other sources of variability are sex and ethnicity. Our findings indicate that exercise hyperaemia following rhythmic contractions at 60% maximum voluntary contraction, is smaller in young black African (BA) men and women than in their white European (WE) counterparts, but larger in men than in women of both ethnicities. We propose the larger absolute force in men causes greater vascular occlusion and accumulation of dilators, while blunted hyperaemia in BAs may reflect lower oxidative capacity and O2 requirement. Nevertheless, COX inhibition attenuated peak hyperaemia by ∼30% in WE, BA men and WE women, indicating PGs make a substantial contribution in all three groups. There was no effect in BA women. Lack of PG involvement may provide early evidence of endothelial dysfunction, consistent in BA women with their greater risk of cardiovascular disease.

A Preliminary Analysis of Relationships between a 1RM Hexagonal Bar Load and Peak Power with the Tactical Task of a Body Drag

A critical job task for law enforcement officers that should be influenced by strength is the body drag. This study analyzed relationships between absolute and relative strength measured by a one-repetition maximum hexagonal bar deadlift (1RM HBD), with body drags completed with 74.84 kg and 90.72 kg dummies. Twenty recreationally-trained individuals completed the 1RM HBD in one session, with peak power measured via a linear position transducer. Over two subsequent sessions, participants dragged the 74.84 kg and 90.72 kg dummies with two techniques. The first technique followed Californian standards, where participants wrapped their arms around the dummy and lifted it to standing before timing commenced. In the adapted technique, timing included the initial manipulation of the dummy. Participants dragged the dummy as quickly as possible over a 9.75 m distance. Partial correlations and linear regression (controlling for sex; p < 0.05) analyzed relationships between the HBD and body drags. The standard 74.84 kg body drag correlated with every HBD variable (r = -0.477 to -0.666), and was predicted by the absolute 1RM HBD (r2 = 0.467). The adapted 74.84 kg drag correlated with all HBD variables (r = -0.535 to - 0.754), and was predicted by peak power and the 1RM HBD (r2 = 0.758). Both 90.72 kg drags correlated with absolute and relative 1RM HBD (r = -0.517 to -0.670). Strength related to all body drags; peak power may be more important for drags with lighter loads. Strength training should be a focus in law enforcement to enhance drag performance.

Weightlifting load effect on intra-limb coordination of lower extremity during pull phase in snatch: Vector coding approach

ABSTRACT This study examined the weightlifting load effects on the lower extremity coordination pattern during a snatch pull movement. Twenty male elite weightlifters performed snatch trials in each of the three load conditions [light (30%), medium (65%) and heavy (90%) of their maximum weightlifting capacities]. Kinematic data for the transition, second pull and take-off phases of a snatch were collected at 200 Hz using an eight-camera motion capture system. Angle-angle plots and coupling angles were calculated for further analyses. The results indicate that participants utilised knee flexion control-strategy in light and medium load conditions during the transition phase, but not for in-phase strategy in heavy load condition. In the second pull phase, participants utilised concurrent ankle dorsiflexion and knee extension, followed by hip extension strategy. The heavy load condition exhibited the distinct coordination strategies before knee extension. In the take-off phase, light and medium load conditions appeared to use thigh-phase strategy (right ankle-knee: p = 0.788, left: p = 0.035, right knee-hip: p = 0.012, left: p = 0.017, right ankle-hip: p = 0.029, left: p = 0.011). This suggests that the heavy load condition requires the use of two-joint coordination patterns (in-phase or anti-phase) as compared to the other lighter load conditions.

Effects of High Intensity Resistance Training on Cardiac Autonomic Modulation in Hypertensive Women

Individuals with arterial hypertension often have an autonomic nervous system (ANS) imbalance with predominance of sympathetic ANS. This predominance can lead to injury of several organs affecting its functioning. There is evidence that performing high intensity resistance training (RT) with heavier loads and a lower number of repetitions results in lower cardiovascular stress when compared with lighter loads and a higher number of repetitions. However, the effects of different protocols of RT in autonomic modulation are not known specially using nonlinear analyses methods. PURPOSE: Analyze and compare the effects of different protocols of high intensity of effort RT on autonomic cardiac modulation of hypertensive women using nonlinear methods. METHODS: A randomized crossover design clinical trial was conducted with 15 postmenopausal hypertensive women who underwent a control session and two high intensity RT protocols involving 6 and 15 repetition maximum (RM). The nonlinear variables that compose Heart Rate Variability (HRV) were collected pre, immediately post, 1 h post, and 24 h post each protocol. Repeated-measures ANOVA were used. RESULTS: The SD1 indices that represent parasympathetic activity in the system were lower in 15RM protocol immediately after the exercise (9.32±11.40) when compared with 6RM (16.38±13.15) and control (19.39±13.40) (p<0.05). The SD2 indices that represent a global variability in the system also were lower in 15RM protocol especially immediately after (13.84±9.57) the exercise when compared with 6RM (24.19±17.50) and control (29.32±17.41) (p<0.05). For the 6RM protocol no relevant clinical changes were observed. CONCLUSIONS: Performing high intensity RT with lower loads and a higher number of repetitions decreases parasympathetic ANS activity, which may be related to an increased cardiovascular stress. On the other hand, heavier load and lower repetition RT did not have a significant impact upon autonomic modulation when compared to a control session.

Adaptive load balancing based on accurate congestion feedback for asymmetric topologies

Datacenter load balancing schemes exist to facilitate parallel data transmission with multiple paths under various uncertainties such as traffic dynamics and topology asymmetries. Taking deployment challenges into account, several optimized schemes (e.g. CLOVE, Hermes) to ECMP balance load at end hosts. However, inaccurate congestion feedback exists in these solutions. They either detect congestion through Explicit Congestion Notification (ECN) and coarse-grained Round-Trip Time (RTT) measurements or are congestion-oblivious. These congestion feedbacks are not sufficient enough to indicate the accurate congestion status under asymmetry. And when rerouting events occur, outdated ACKs carrying congestion feedback of other paths can improperly influence the current sending rate. After our observations and analyses, these inaccurate congestion feedback can degrade performance.Therefore, we explore how to address above problems while ensuring good adaptation to existing switch hardware and network protocol stack. We propose ALB, an adaptive load balancing mechanism based on accurate congestion feedback running at end hosts, which is resilient to asymmetry. ALB leverages a latency-based congestion detection to precisely reroute new flowlets to the paths with lighter load, and an ACK correction method to avoid inaccurate flow rate adjustment. In large-scale simulations, ALB achieves up to 13% and 48% better average flow completion time (FCT) than CONGA and CLOVE-ECN under asymmetry, respectively. And compared with other schemes ALB improves the average and the 99th percentile FCTs for small flows under high bursty traffic by 43–174% and 75–129%. Under the situation of dynamic network changes, ALB also provides competitive overall performance and maintains stable performance for small flows.

Fundamental research on the effective contact area of micro-/nano-textured surface in triboelectric nanogenerator

The triboelectric nanogenerator (TENG) is a new energy technology to convert mechanical energy into electricity based on contact electrification and electrostatic induction. An effective way to improve power generation of TENG is to increase the effective contact area through introducing micro-/nano-textures onto the contact surface. However, the definition and quantitative analysis on the “effective” contact area of micro-/nano-textures is still in doubt so that the design of surface texture to improve the output of TENG is lack of theoretical basis. In this paper, an adhesive contact model considering textures is established, and the computational methods such as inexact Newton method, bi-conjugate stabilized (Bi-CGSTAB) method and fast Fourier transform (FFT) technique are employed to quantitatively analyze the effects of applied force and texture size on the effective contact area and open-circuit voltage. On the other hand, the pyramid textured surfaces of TENG are fabricated through lithography, wet etching and replication techniques, the test platforms of contact area and electrical output for TENGs are constructed as well, and results from simulation and experiment are compared at last. It is shown that, firstly, the four sides of pyramid texture are involved in the contact electrification and therefore the effective contact area should be the sum of the pyramid lateral area involved in contact when contact only happens in texture region, or the sum of pyramid lateral area and flat area involved in contact when contact happens in both texture and flat regions. Secondly, under lighter loading, the open-circuit voltage of TENGs with pyramid textures increases due to the increase of contact area, while under heavier loading, the open-circuit voltage remains stable due to the unchanged contact area. In addition, the contact area and open-circuit voltage of TENGs will increase with increased texture pitch under lighter applied force while decrease with increased texture pitch under heavier applied force. This study reveals the correlation between the contact area and electrical performance of TENG with textured surfaces and provides theoretical basis for texture design of TENG.

The Effects of Ballistic and Nonballistic Bench Press on Mechanical Variables.

Moir, GL, Munford, SN, Moroski, LL, Davis, SE. The effects of ballistic and nonballistic bench press on mechanical variables. J Strength Cond Res 32(12): 3333-3339, 2018-The purpose of this study was to investigate the effects of ballistic and nonballistic bench press performed with loads equivalent to 30 and 90% 1 repetition maximum (1RM) on mechanical variables. Eleven resistance-trained men (age: 23.0 ± 1.4 years; mass: 98.4 ± 14.4 kg) attended 4 testing sessions where they performed one of the following sessions: (a) 3 sets of 5 nonballistic repetitions performed with a load equivalent to 30% 1RM (30N-B), (b) 3 sets of 5 ballistic repetitions performed with a load equivalent to 30% 1RM (30B), (c) 3 sets of 4 nonballistic repetitions with a load equivalent to 90% 1RM (90N-B), or (d) 3 sets of 4 ballistic repetitions with a load equivalent to 90% 1RM (90B). Force plates and a 3-dimensional motion analysis system were used to determine the velocity, force, power output (PO), and work during each repetition. The heavier loads resulted in significantly greater forces applied to the barbell (mean differences: 472-783 N, p < 0.001), but lower barbell velocities (mean differences: 0.85-1.20 m·s, p < 0.001) and PO (mean differences: 118-492 W, p ≤ 0.022). The ballistic conditions enhanced the mechanical variables only at the lower load, with 30B producing significantly greater force (mean difference: 263 N, p < 0.001), velocity (mean difference: 0.33 m·s, p < 0.001), and PO (mean difference: 335 W, p < 0.001) compared with 30N-B. Furthermore, the increase in PO across the 3 sets in 30B was significantly different from all other conditions (p = 0.013). The total mechanical work performed was significantly greater for the conditions with the heavier loads compared with those with the lighter loads (mean differences: 362-5,600 J, p < 0.001) and that performed during the ballistic conditions was significantly greater than that performed during the nonballistic conditions with the same load (mean differences: 945-1,030 J, p < 0.001). Ballistic bench press may be an effective exercise for developing PO, and multiple sets may elicit postactivation potentiation that enhances force production. However, these benefits may be negated at heavier loads.

Heavier- and lighter-load isolated lumbar extension resistance training produce similar strength increases, but different perceptual responses, in healthy males and females.

ObjectivesMuscles dominant in type I muscle fibres, such as the lumbar extensors, are often trained using lighter loads and higher repetition ranges. However, literature suggests that similar strength adaptations can be attained by the use of both heavier- (HL) and lighter-load (LL) resistance training across a number of appendicular muscle groups. Furthermore, LL resistance exercise to momentary failure might result in greater discomfort.DesignThe aims of the present study were to compare strength adaptations, as well as perceptual responses of effort (RPE-E) and discomfort (RPE-D), to isolated lumbar extension (ILEX) exercise using HL (80% of maximum voluntary contraction; MVC) and LL (50% MVC) in healthy males and females.MethodsTwenty-six participants (n = 14 males, n = 12 females) were divided in to sex counter-balanced HL (23 ± 5 years; 172.3 ± 9.8 cm; 71.0 ± 13.1 kg) and LL (22 ± 2 years; 175.3 ± 6.3 cm; 72.8 ± 9.5 kg) resistance training groups. All participants performed a single set of dynamic ILEX exercise 1 day/week for 6 weeks using either 80% (HL) or 50% (LL) of their MVC to momentary failure.ResultsAnalyses revealed significant pre- to post-intervention increases in isometric strength for both HL and LL, with no significant between-group differences (p > 0.05). Changes in strength index (area under torque curves) were 2,891 Nm degrees 95% CIs [1,612–4,169] and 2,865 Nm degrees 95% CIs [1,587–4,144] for HL and LL respectively. Changes in MVC were 51.7 Nm 95% CIs [24.4–79.1] and 46.0 Nm 95% CIs [18.6–73.3] for HL and LL respectively. Mean repetitions per set, total training time and discomfort were all significantly higher for LL compared to HL (26 ± 8 vs. 8 ± 3 repetitions, 158.5 ± 47 vs. 50.5 ± 15 s, and 7.8 ± 1.8 vs. 4.8 ± 2.5, respectively; all p < 0.005).ConclusionsThe present study supports that that low-volume, low-frequency ILEX resistance exercise can produce similar strength increases in the lumbar extensors using either HL or LL. As such personal trainers, trainees and strength coaches can consider other factors which might impact acute performance (e.g. effort and discomfort during the exercise). This data might prove beneficial in helping asymptomatic persons reduce the risk of low-back pain, and further research, might consider the use of HL exercise for chronic low-back pain symptomatic persons.

Explosive Resistance Training Using Elastic Bands in Young Female Team Handball Players.

The aim of the study was to examine the effects of full-body elastic resistance band training in young female team handball players. 12 players (16.5±0.7 years, 166±5.0 cm, 65.9±8.8 kg) completed an 11-week control period followed by a 9-week elastic resistance band training period. The training program, consisting of 6 exercises, was incorporated into the teams’ regular handball training sessions 3 times per week. Each exercise was performed with 3 sets of 6–10 explosive repetitions (5–9 on the Borg CR10 Scale®). The maximal power output in squat and bench press, jump height, throwing velocity and repeated agility run was tested before and after the control and training periods. The elastic resistance band period had greater improvement vs. the control period for countermovement jump with or without arm swing (10% vs. –6 to –2%) and power output at lighter loads (10 to 12% vs. –6 to 0%). For the 3 throwing velocity tests, there were tendencies towards increased velocity in the elastic resistance band period compared to the control period ( p =0.07–0.10). For the repeated agility run, there was a reduction in the mean and fastest time compared to the training period (2 to 3% vs. –1 to 1%). In conclusion, a brief, elastic resistance band training program, incorporated into the regular handball training sessions, improved explosive lower-limb performance in young female handball players more than handball training alone.

Study of High-Voltage Power Supply for Electronic Beam Welder Based on Soft-switching Technology

Due to the lower frequency of traditional high-voltage power supply for Electronic Beam Welder(EBW) and larger volume and weight of transformer, the working frequency of the inverter circuit is improved to reduce the volume and weight of transformer. The soft switch of power tube is implemented using the LC resonant converter. Soft switch technology is also utilized to avoid the harmonic and to reduce the switching loss when the power tube opens and shuts off under high speed. The working principle of LC resonant converter is also analyzed. The fault that the voltage is hard to change by FM in lighter load is avoided using BUCK circuit to adjust busbar voltages. The rationality of design is demonstrated by debugging the high-voltage power supply for EBW, and analyzing the test parameters.

Wireless Photoelectric Sensor Network Scheduling Algorithm Based on Divisible Load

To discuss the divisible load scheduling in wireless photoelectric sensor networks, a load scheduling algorithm called EDDLT based on residual energy landscape is proposed. In the algorithm, the constant of the time needed for the induction and reporting unit data is adjusted to the variable parameters based on the residual energy. In addition, the ratio of the initial energy to the residual energy is used to carry out the effective load scheduling. By using this algorithm, when the load is allocated to each sensor node, the remaining energy of nodes is considered, and a lighter load is allocated to sensor nodes with less residual energy. EDDLT, compared to the standard divisible load scheduling method SDLT, the number of execution rounds is greatly increased when the first sensor node is dead. The experimental results showed that EDDLT had a certain effect on prolonging the lifetime of wireless photoelectric sensor networks. To sum up, the scheduling algorithm has good performance in exploring divisible load.

Acute effects of different resistance training loads on cardiac autonomic modulation in hypertensive postmenopausal women

BackgroundIndividuals with arterial hypertension often have an autonomic nervous system (ANS) imbalance with predominance of sympathetic ANS. This predominance can lead to injury of several organs affecting its functioning. There is evidence that performing high intensity resistance training (RT) with heavier loads and a lower number of repetitions results in lower cardiovascular stress when compared with lighter loads and a higher number of repetitions. However, the effects of different protocols of RT in autonomic modulation are not known. Therefore, the aim of the study was to analyze and compare the effects of different protocols of high intensity of effort RT on autonomic cardiac modulation of hypertensive women.MethodsA randomized crossover design clinical trial was conducted with 15 postmenopausal hypertensive women who underwent a control session and two high intensity RT protocols involving 6 and 15 repetition maximum (RM). Heart rate variability (HRV), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and double product (DP) were collected pre, immediately post, 1 h post, and 24 h post each protocol. Repeated-measures ANOVA were used.ResultsSBP was higher for 6RM than control immediately after session (p < 0.05). There were no differences for DBP among protocols (p ≥ 0.05). HR was higher for 15RM than 6RM and control immediately after and 1 h after session (p ≤ 0.05). DP values for 15RM were significantly higher than 6RM and control immediately after the session and remained higher than control 1 h after session (p ≤ 0.05). The indices that compose HRV (rMSSD) were lower after 15RM than 6RM and control (p ≥ 0.05). The parameters of parasympathetic activity (HF) were decreased and sympathetic (LF) activity was increased for 15RM when compared to the 6RM and control session immediately after the exercise session (p ≤ 0.05).ConclusionPerforming high intensity RT with lower loads and a higher number of repetitions seems to promote acute increases in sympathetic ANS activity, which may be related to cardiovascular stress. On the other hand, heavier load and lower repetition RT did not significantly impact upon autonomic modulation when compared to a control session.

Intention, attention and long-term memory for visual scenes: It all depends on the scenes

Humans have an ability to remember up to 10,000 previously viewed scenes with apparently robust memory for visual detail, a phenomenon that has been interpreted as suggesting a visual memory system of massive capacity. Attempts at explanation have largely focused on the nature of the stimuli and been influenced by theoretical accounts of object recognition. Our own study aims to supplement this by considering two observer-based aspects of visual long-term memory, one strategic, whether the observers are aware or not that their memory will subsequently be tested and the other executive, based on the amount of attentional capacity available during encoding. We describe six studies involving visual scenes ranging in difficulty from complex manmade scenes (d′ = 2.54), to door scenes with prominent features removed (d′ = 0.79). To ensure processing of the stimuli, all participants have to make a judgement of pleasantness (Experiments 1 and 2) or of the presence or absence of a dot (Experiment 3). Intention to learn influence performance only in the most impoverished condition comprising doors with prominent features removed. Experiments 4–6 investigated the attentional demands of visual long-term memory using a concurrent task procedure. While the demanding task of counting back in threes clearly impaired performance across the range of materials, a lighter load, counting back in ones influences only the most difficult door scenes. Detailed analysis of error patterns indicated that clear differences in performance level between manmade and natural scenes and between unmodified and modified door scenes was reflected in false alarm scores not detections, while concurrent task load affected both. We suggest an interpretation in terms of a two-level process of encoding at the visual feature rather than the whole scene level, with natural images containing many features encoded richly, rapidly and without explicit intent. Only when scenes are selected from a single category and with distinctive detail minimised does memory depend on intention to remember and on the availability of substantial executive capacity.

Loadbearing capacity of infill masonry walls considering the deformation‐based membrane effect

AbstractAccording to currently valid codes, it is not possible to determine the loadbearing capacity of unreinforced infill walls considering the deformation‐based membrane effect by incorporating the exact support conditions. One reason for this is the lack of a validated calculation procedure, which in addition to the equilibrium conditions also realistically represents the compatibility conditions of these systems. In the present paper, therefore, a new non‐linear analytical calculation procedure is presented. The main focus of the analysis of walls subject to area loading is the incorporation of the support conditions and thus the consideration of the deformation‐based membrane compressive force. Through generalised formulation and a standardised notation of the determination equations, different material behaviours and various support conditions can be taken into account with few parameters. On the action side, both lighter loading like wind loads and heavier loading like explosion loads can be considered. Through the implementation of the partial factor concept, it is possible to comply with the requirements of European codes and thus ensure the applicability of the analysis model.

Reduction of lateral earth pressure using Geo-foam blocks

Geo-foam is an expanded polystyrene (EPS) or extruded polystyrene manufactured into large lightweight blocks. EPS Geo-foam density is only about 1% that of soil and rock, making it a superior, ultra-lightweight fill material that significantly reduces the stress on underlying subgrades. The lighter load can reduce settlements and can improve stability against bearing and slope failures. Geo-foam offers special advantages for construction on soft ground, slope stabilization, and retaining walls. A parametric study is carried out using ADINA program, different values of Geo-foam thickness (t), and Geo-foam height (H). Loaded and unloaded retaining wall models are also studied. The study aims at achieving the lowest possible stresses in both soil and the retaining wall body. This will reduce the expected soil settlement. Results showed that the most effective and preferable value of the Geo-foam thickness (t) is equal to 1.00 m. Numerical results pointed indicated that the decrease in soil settlement was about 35% when using Geo-foam of thickness equal to 1.00 m. Also, results showed that soil settlements and lateral stresses decreased by about 20% for loaded cases for different values of the Geo-foam thickness when compared with unloaded ones.

Training at maximal power in resisted sprinting: Optimal load determination methodology and pilot results in team sport athletes.

AimsIn the current study we investigated the effects of resisted sprint training on sprinting performance and underlying mechanical parameters (force-velocity-power profile) based on two different training protocols: (i) loads that represented maximum power output (Lopt) and a 50% decrease in maximum unresisted sprinting velocity and (ii) lighter loads that represented a 10% decrease in maximum unresisted sprinting velocity, as drawn from previous research (L10).MethodsSoccer [n = 15 male] and rugby [n = 21; 9 male and 12 female] club-level athletes were individually assessed for horizontal force-velocity and load-velocity profiles using a battery of resisted sprints, sled or robotic resistance respectively. Athletes then performed a 12-session resisted (10 × 20-m; and pre- post-profiling) sprint training intervention following the L10 or Lopt protocol.ResultsBoth L10 and Lopt training protocols had minor effects on sprinting performance (average of -1.4 to -2.3% split-times respectively), and provided trivial, small and unclear changes in mechanical sprinting parameters. Unexpectedly, Lopt impacted velocity dominant variables to a greater degree than L10 (trivial benefit in maximum velocity; small increase in slope of the force-velocity relationship), while L10 improved force and power dominant metrics (trivial benefit in maximal power; small benefit in maximal effectiveness of ground force orientation).ConclusionsBoth resisted-sprint training protocols were likely to improve performance after a short training intervention in already sprint trained athletes. However, widely varied individualised results indicated that adaptations may be dependent on pre-training force-velocity characteristics.

Comparison of Pigtail with J Anchor Bolt in Normal Concrete

Anchor bolts have been used to attach the steel structure of concrete and transfer load into the concrete. Anchor bolts in concrete are to withstand the shear force as they connect steel beams to the reinforced concrete foundations. The research was carried out to increase the understanding and investigating the performance of anchor bolts Pigtail since there is a lack of research on the bolt and to compare it with anchor bolts J which have been widely used by the industry. According to the methodology, testing the tensile load was used in this research to get a maximum load capacity of the anchor bolt in concrete. The sample was embedded in concrete cylinders of 75mm radius and 300mm height. Depths of embedment were 200mm, 230mm, and 260mm. The Universal Testing Machine, UTM was used to test the strength of tensile. 12 samples were used, each type and depth used two samples to get the average value using concrete grade 30. The samples underwent the process of curing for 28 days. The anchor bolts J used a 40mm bending radius and the length of hook was 100mm. Anchor bolts pigtail also used the 10 bending radius with depth of 8mm that have been compressed using 16mm radius rigs with a load of 500kN. Results of the research showed the depth of 260mm for Pigtail almost the same with J 60.529kN and 53.628kN and anchor bolts J were 75.557kN and 76.332kN. Difference of the values was not too far vary when compared with the 200mm and 230mm depths. Each comparison showed the ability of each bolt and anchor bolt failure occurred. Performance of the anchor bolts pigtail can be used on a structure or a higher load at an embedment of 260mm. Embedment of 200mm and 230mm can be used on a lighter load if steel material saving is a priority in every usage.

LED 램프를 위한 지능형 범용 드라이버 회로 설계

This paper presents a universal driver circuit for light emitting diode (LED) using linear current regulation technology. The proposed driver circuit has a unique feature (i.e., universality) which operates in both alternating current (AC) or direct current (DC) domain of the supply. Additional features, such as improved power factor, lower self-power consumption, lower cost, design simplicity for higher load makes it distinctive than existing LED driver circuits in the market. To verify the feasibility of the proposed driver circuit, a laboratory prototype has been designed and checked from lighter load (3 watt) to the higher load (30 watt).

Heavy vs Light Load Single-Joint Exercise Performance with Different Rest Intervals.

The aim of the study was to compare the effect of three distinct rest period lengths between sets of upper body single-joint exercise with different load zones and volume designed for either endurance or hypertrophy (50% or 80% of 1-RM). Sixteen trained men (20.75 ± 2.54 years; 76.35 ± 5.03 kg; 176.75 ± 3.33 cm, 24.53 ± 1.47 kg/m2) performed a test and retest of 1-RM on non-consecutive days. Forty-eight hours after load testing, the participants were randomly assigned to six sessions consisting of four sets of the triceps pull-down, combining different intensities with distinct rest periods between sets. The shorter 1 minute rest promoted a significant reduction in the total repetition number compared to 3 minute rest for both workloads. There was a difference between 3 and 5 minute conditions for the 50% of 1-RM that did not occur for the 80% of 1-RM condition. Both intensities presented significant interaction values for the rest conditions vs. each set (50% p = 0.0001; 80% p = 0.0001). Additionally, significant values were found for the main effect of the performance of subsequent sets (50% p = 0.003; 80% p = 0.001) and rest conditions (50% p = 0.0001; 80% p = 0.0001). In conclusion, for heavier loads (80%) to fatigue, longer rest of 3 to 5 minutes seems to allow for better recovery between sets and thus, promotes a greater volume. However, when training with lighter loads (50%), the magnitude of the rest seems to directly affect the performance of subsequent sets, and also presents a correlation with total volume achieved for the upper body single-joint exercise scheme.