Publications by authors named "Nikola Grujic"

Earthworms are a key faunal group in agricultural soils, but little is known on how farming systems affect their communities across wide climatic gradients and how farming system choice might mediate earthworms' exposure to climate conditions. Here, we studied arable soil earthworm communities on wheat fields across a European climatic gradient, covering nine pedo-climatic zones, from Mediterranean to Boreal (S to N) and from Lusitanian to Pannonian (W to E). In each zone, 20-25 wheat fields under conventional or organic farming were sampled.

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Pupil size is a widely used metric of brain state. It is one of the few signals originating from the brain that can be readily monitored with low-cost devices in basic science, clinical, and home settings. It is, therefore, important to investigate and generate well-defined theories related to specific interpretations of this metric.

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Does the brain track how fast our blood glucose is changing? Knowing such a rate of change would enable the prediction of an upcoming state and a timelier response to this new state. Hypothalamic arousal-orchestrating hypocretin/orexin neurons (HONs) have been proposed to be glucose sensors, yet whether they track glucose concentration (proportional tracking) or rate of change (derivative tracking) is unknown. Using simultaneous recordings of HONs and blood glucose in behaving male mice, we found that maximal HON responses occur in considerable temporal anticipation (minutes) of glucose peaks due to derivative tracking.

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Information seeking, such as standing on tiptoes to look around in humans, is observed across animals and helps survival. Its rodent analog-unsupported rearing on hind legs-was a classic model in deciphering neural signals of cognition and is of intense renewed interest in preclinical modeling of neuropsychiatric states. Neural signals and circuits controlling this dedicated decision to seek information remain largely unknown.

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Brain orexin (hypocretin) neurons are implicated in sleep-wake switching and reward-seeking but their roles in rapid arousal dynamics and reward perception are unclear. Here, cell-specific stimulation, deletion and in vivo recordings revealed strong correlative and causal links between pupil dilation-a quantitative arousal marker-and orexin cell activity. Coding of arousal and reward was distributed across orexin cells, indicating that they specialize in rapid, multiplexed communication of momentary arousal and reward states.

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Behavior exhibited by humans and other organisms is generally inconsistent and biased and, thus, is often labeled irrational. However, the origins of this seemingly suboptimal behavior remain elusive. We developed a behavioral task and normative framework to reveal how organisms should allocate their limited processing resources such that sensory precision and its related metabolic investment are balanced to guarantee maximal utility.

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Saccadic eye movements, which dramatically alter retinal images, are associated with robust perimovement perceptual alterations. Such alterations, thought to reflect brain mechanisms for maintaining perceptual stability in the face of saccade-induced retinal image disruptions, are often studied by asking subjects to localize brief stimuli presented around the time of horizontal saccades. However, other saccade directions are not usually explored.

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Introduction: Anaerobic capacity is much less evaluated in literature compared to aerobic component. Anaerobic performance of athletes can be measured using different motoric tests, lasting 20 to 30 seconds, one of them being the Wingate anaerobic test (WAnT).

Objective: The aim of this study was to determine the work performed and power generated by athletes and non-athletes during a 30-second high intensity exercise, as well as to compare explosive characteristics of subjects using a new parameter of WAnT, named explosive power, or slope of power.

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Context: As a result of the adaptation process, some functional properties show different functions over time during strength training. Muscle strength and fatigue may show different adaptation patterns in reaching the improvement plateau after several weeks of training.

Objective: To follow muscle endurance and fatigue values during resistance training of the elbow extensors in young nonathletes.

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Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow- and pressure-generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non-athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age- and gender-matched healthy sedentary controls participated in this study.

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Background: Bradykinin type 2 receptor (B2BRK) genotype was reported to be associated with changes in the left-ventricular mass as a response to aerobic training, as well as in the regulation of the skeletal muscle performance in both athletes and non-athletes. However, there are no reports on the effect of B2BRK 9-bp polymorphism on the response of the skeletal muscle to strength training, and our aim was to determine the relationship between the B2BRK SNP and triceps brachii functional and morphological adaptation to programmed physical activity in young adults.

Methods: In this 6-week pretest-posttest exercise intervention study, twenty nine healthy young men (21.

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Cardiac power output (CPO) is a unique and direct measure of overall cardiac function (i.e. cardiac pumping capability) that integrates both flow- and pressure-generating capacities of the heart.

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Purpose: To determine the triceps brachii functional adaptation and regional body composition changes after 12 months of detraining.

Materials And Methods: Seventeen healthy young men (22.2 ± 1.

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The 30-s all-out Wingate test has been used in athletes of all sport specialties to measure the capacity for short duration, high power output while cycling. The aim of this study was to establish differences in measuring anaerobic capacity between the classic Wingate test on a cycling ergometer and the modified Wingate test on a rowing ergometer in rowers. A group of20 rowers was tested by both the cycle and rowing ergometers during 30s of maximum power to test anaerobic capacity and to make correlation between these tests.

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The aim of this study was to determine whether triceps brachii muscle volume can be adequately estimated from a single anatomical cross-sectional area (ACSA) and can the same model be used for prediction after training. Thirty-five healthy male non-athletes (age 21.6 ± 2.

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The effects of different recovery protocols on heart rate recovery (HRR) trend through fitted heart rate (HR) decay curves were assessed. Twenty one trained male athletes and 19 sedentary male students performed a submaximal cycle exercise test on four occasions followed by 5 min: 1) inactive recovery in the upright seated position, 2) active (cycling) recovery in the upright seated position, 3) supine position, and 4) supine position with elevated legs. The HRR was assessed as the difference between the peak exercise HR and the HR recorded following 60 seconds of recovery (HRR60).

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The aim of this study was to determine morphological and functional changes of the elbow extensor muscles in response to a 12-week self-perceived maximal resistance training (MRT). Twenty-one healthy sedentary young men were engaged in elbow extensor training using isoacceleration dynamometry for 12 weeks with a frequency of five sessions per week (five sets of ten maximal voluntarily contractions, 1-min rest period between each set). Prior to, at 6 weeks and after the training, a series of cross-sectional magnetic resonance images of the upper arm were obtained and muscle volumes were calculated.

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Our aim was to determine the dynamics in muscle strength increase and fatigue development during repetitive maximal contraction in specific maximal self-perceived elbow extensors training program. We will derive our functional model for m. triceps brachii in spirit of traditional Hill's two-component muscular model and after fitting our data, develop a prediction tool for this specific training system.

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Muscle cell adaptation to physical activity is well known. Hypertrophy is one of the basic changes but metabolic changes are following the anatomic ones as well. The aim of the study was to follow up the changes of the ergometric parameters and surface area of the thigh muscles evoked by the heavy resistance strength training.

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Background/aim: The Wingate anaerobic test is a valid and reliable method of measuring anaerobic capacity. The aim of this study was to determine whether other modified test can be used instead of the Wingate test.

Methods: A group of 30 sedentary young men were first tested with a cycle ergometer (classic Wingate test), and then with a dynamometer during 30 s of "all out" leg extension exercise (modified Wingate test; WAnTe) in order to test anaerobic capacity.

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The purpose of this study was to assess the effect of three different body positions on HRV measures following short-term submaximal exercise. Thirty young healthy males performed submaximal cycling for five minutes on three different occasions. Measures of HRV were obtained from 5-min R to R wave intervals before the exercise (baseline) and during the last five minutes of a 15 min recovery (post-exercise) in three different body positions (seated, supine, supine with elevated legs).

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Introduction: Several studies show that nursing is, by its very nature, an occupation exposed to a high degree of stress. The main aims of the present research were to analyze the presence and to identify occupational stress factors and assess stress levels among nurses in clinical/hospital settings.

Material And Methods: The research was conducted as a cross-sectional study.

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The aim of this study was to investigate the values of anaerobic energetic capacity variables in athletes engaged in different sport disciplines and to compare them in relation to specific demands of each sport. Wingate anaerobic tests were conducted on 145 elite athletes (14 boxers, 17 wrestlers, 27 hockey players, 23 volleyball players, 20 handball players, 25 basketball players, and 19 soccer players). Three variables were measured as markers of anaerobic capacity: peak power, mean power, and explosive power.

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Purpose: To evaluate the effect of 6-week self-perceived maximal resistance training on muscle volume utilizing magnetic resonance imaging and maximal, average, and endurance strength of the elbow extensors and to assess the relationship between muscle strength and volume before and after the training.

Materials And Methods: This was a prospective blinded study. A total of 15 healthy untrained men, aged 22.

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Introduction: A number of articles on physical activity analyze the effects of acute bouts of physical exercise on the whole body. These experiments mainly include questionnaires and measurements of reaction time. The use of event-related potentials in laboratories for functional diagnostics is only of recent date.

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