The organization and temporal properties of appetitive behavior in rats     

Kathleen M. Silva  William Timberlake 《Learning & behavior》1998,26(2):182-195

In the presence and absence of an externalinterfood clock stimulus (a sequence of flashing lights), rats showed a multimodal behavior pattern during successive quarters of interfood intervals (IFI) ranging from 12 to 192 sec. Responses near the feeder peaked before and just after food presentations, whereas locomotion remote from the feeder peaked toward the middle of the IFI. The temporal patterns of nosing in the feeder and remote locomotion were scalar (the time at which a response peaked in the IFI was proportional to the IFI length), whereas the patterns of postfood feeder-directed behavior, rearing, and pawgrooming were time bound (peaking at a fixed time after food, regardless of IFI length). Responses varied in their control by the external clock stimulus. During the last half of the IFI, rats nosed in the feeder more with an external clock, but only at intermediate IFIs. During the first quarter of the IFI, rats pawgroomed more with an external clock, but only at the longest IFI. The general sequence of responses during the interfood clock was consistent with the view that food delivery engages an organized sequence of search states that are expressed through a variety of responses.  相似文献   

Exploring features for the automatic identification of user goals in web search     

Mauro Rojas Herrera  Edleno Silva de Moura  Marco Cristo  Thomaz Philippe Silva  Altigran Soares da Silva 《Information processing & management》2010

Queries submitted to search engines can be classified according to the user goals into three distinct categories: navigational, informational, and transactional. Such classification may be useful, for instance, as additional information for advertisement selection algorithms and for search engine ranking functions, among other possible applications. This paper presents a study about the impact of using several features extracted from the document collection and query logs on the task of automatically identifying the users’ goals behind their queries. We propose the use of new features not previously reported in literature and study their impact on the quality of the query classification task. Further, we study the impact of each feature on different web collections, showing that the choice of the best set of features may change according to the target collection.  相似文献   

History effects on induced and operant variability     

da Silva Souza A  Abreu-Rodrigues J  Baumann AA 《Learning & behavior》2010,38(4):426-437

Two experiments evaluated history effects on induced and operant variability. College students typed three-digit sequences on a computer keyboard. Sequence variability was induced (by no reinforcement or variation- independent reinforcement) or reinforced (by variation- or repetition-dependent reinforcement). Conditions with induced and operant variability were presented according to a reverse between-groups design. In Experiment 1, we examined transitions from the variation or repetition contingencies to no reinforcement, and vice versa. In Experiment 2, the variation or repetition contingencies were followed or preceded by variation-independent reinforcement. The results showed that (1) a history of no reinforcement impaired operant variability learning; (2) induced variability levels were higher and lower after a history of reinforcement for variation and repetition, respectively; (3) repetition was more easily disrupted by no reinforcement and independent reinforcement than was variation; and (4) response variability and stability were a function of past and current reinforcement conditions. These results indicate that reinforcement history influences both induced and operant variability levels.  相似文献   

The effects of resistance training volume on osteosarcopenic obesity in older women     

Paolo M. Cunha  Alex S. Ribeiro  Crisieli M. Tomeleri  Brad J. Schoenfeld  Analiza M. Silva  Mariana F. Souza 《Journal of sports sciences》2018,36(14):1564-1571

The aim of this study was to analyze the effects of resistance training (RT) performed with 1 or 3 sets per exercise on osteosarcopenic obesity (OSO) syndrome parameters in older women. Sixty-two older women (68.0 ± 4.3 years, 26.8 ± 4.4 kg/m²) participated in a 12-week RT program. Participants were randomly assigned into one of the three groups: two training groups that performed either 1 set (G1S, n = 21) or 3 sets (G3S, n = 20) 3 times weekly, or a control group (CG, n = 21). Body composition was assessed by dual X-ray absorptiometry, strength was evaluated by 1 repetition maximum testing. The G3S presented significantly higher strength changes than G1S. The changes for percentage of body fat were higher for G3S compared to G1S. There was no difference in skeletal muscle mass between G3S and G1S, however both training groups displayed greater increases in this outcome compared to CG. There was no effect for bone mineral density. The overall analysis indicated higher (P < 0.05) positive changes for G3S than G1S (composed Z-score: G3S = 0.62 ± 0.40; G1S = 0.11 ± 0.48). The results suggest that a 12-week RT period is effective to improve the risk factors of OSO, and that 3 sets induce higher improvements than a single set.  相似文献   

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats     

Helenita Antonia de Oliveira  Ednei Luiz Antonio  Flávio André Silva  Paulo de Tarso Camillo de Carvalho  Regiane Feliciano  Amanda Yoshizaki 《Journal of sports sciences》2018,36(20):2349-2357

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.  相似文献   

Do the Demographic Differences Manifest in Motivation to Learn Science and Impact on Science Performance? Evidence from Sri Lanka     

Anthoni Durage Asoka De Silva  Ali Khatibi  S. M. Ferdous Azam 《International Journal of Science and Mathematics Education》2018,16(1):47-67

The present study examined whether gender, ethnicity, instructional medium and school category differences manifest in science performance and motivation to learn science among secondary school students in Sri Lanka. The mean of five successive term test scores was used as the measure of science performance. Level of motivation in terms of six dimensions was measured by using the Science Motivation Questionnaire. A sample of 1316 grade 11 students representing Sinhala, Tamil, and Muslim ethnic groups from the three categories of public schools, which provide instructions in the vernacular languages of Sinhala or Tamil, participated in the study. Girls showed significantly higher performance in science compared to boys, and there was a significant gender difference in the levels of motivational dimensions in favor of girls. Although Tamil medium students possessed a higher level of motivation to learn science, Sinhala medium students outperformed their Tamil medium counterparts in science performance. Significant differences in science performance between Sinhala, Tamil, and Muslim students were also observed. However, motivation towards learning science between Tamils and Muslims was not significantly different. Highly significant differences in both motivation to learn science and performance in science were found between three categories of schools. The present study provides information to education officials who have to achieve equity across gender, ethnicity, medium of instruction, and school category, teachers who deliver the subject and school principals who design academic support programs.  相似文献   

The influence of pitch dimensions on performance during small-sided and conditioned soccer games     

Luís Vilar  Ricardo Duarte  Pedro Silva  Jia Yi Chow  Keith Davids 《Journal of sports sciences》2013,31(19):1751-1759

Abstract

This study examined the influence of pitch dimensions in small-sided soccer games in shaping opportunities for performers to maintain ball possession, pass to teammates and shoot at goal. Fifteen amateur standard male participants (M = 21.87, σ = 1.96 years) played 5 v 5 small-sided soccer games in three varying pitch conditions (28 m × 14 m, 40 m × 20 m and 52 m × 26 m). Thirty sequences of play in each condition were selected for digitisation using TACTO software, allowing the capture of bi-dimensional displacement coordinate data of all players and the ball. The values of interpersonal distance between all attackers and immediate defenders and the relative distances of defenders to intercept a shot and a pass were computed as dependent variables. Results showed existence of fewer opportunities to maintain ball possession on smaller pitches, compared to medium and larger pitches. Conversely, the different dimensions set to the pitch did not influence opportunities for players to shoot at goal, or to perform passes to other teammates. By examining the specific spatial–temporal relationships of players and key-task constraints, the data from this study explain how effects of manipulating pitch dimensions of small-sided games might enhance opportunities for acquiring specific movement and decision-making skills.  相似文献   

Creatine supplementation does not decrease oxidative stress and inflammation in skeletal muscle after eccentric exercise     

Luciano A. Silva  Camila B. Tromm  Guilherme Da Rosa  Karoliny Bom  Thais F. Luciano  Talita Tuon 《Journal of sports sciences》2013,31(11):1164-1176

Abstract

Thirty-six male rats were used; divided into 6 groups (n = 6): saline; creatine (Cr); eccentric exercise (EE) plus saline 24 h (saline + 24 h); eccentric exercise plus Cr 24 h (Cr + 24 h); eccentric exercise plus saline 48 h (saline + 48 h); and eccentric exercise plus Cr 48 h (Cr + 48h). Cr supplementation was administered as a solution of 300 mg · kg body weight^?1 · day^?1 in 1 mL water, for two weeks, before the eccentric exercise. The animals were submitted to one downhill run session at 1.0 km · h^?1 until exhaustion. Twenty-four and forty-eight hours after the exercise, the animals were killed, and the quadriceps were removed. Creatine kinase levels, superoxide production, thiobarbituric acid reactive substances (TBARS) level, carbonyl content, total thiol content, superoxide dismutase, catalase, glutathione peroxidase, interleukin-1b (IL-1β), nuclear factor kappa B (NF-kb), and tumour necrosis factor (TNF) were analysed. Cr supplementation neither decreases Cr kinase, superoxide production, lipoperoxidation, carbonylation, total thiol, IL-1β, NF-kb, or TNF nor alters the enzyme activity of superoxide dismutase, catalase, and glutathione peroxides in relation to the saline group, respectively (P < 0.05). There are positive correlations between Cr kinase and TBARS and TNF-α 48 hours after eccentric exercise. The present study suggests that Cr supplementation does not decrease oxidative stress and inflammation after eccentric contraction.  相似文献   

A Psychophysiological Assessment of Elite Wrestlers     

John M. Silva III  Barry B. Shultz  Robert W. Haslam  Donald Murray 《Research quarterly for exercise and sport》2013,84(3):348-358

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Technical Reliability Assessment of the Actigraph GT1M Accelerometer     

Pedro Silva  Jorge Mota  Dale Esliger  Gregory Welk 《Measurement in physical education and exercise science》2013,17(2):79-91

The purpose of this study was to determine the reliability of the Actigraph GT1M (Pensacola, FL, USA) accelerometer activity count and step functions. Fifty GT1M accelerometers were initialized to collect simultaneous acceleration counts and steps data using 15-sec epochs. All reliability testing was completed using a mechanical shaker plate to perform six different test conditions in Experiment 1 and 18 test conditions in Experiment 2. The overall intra- and inter-instrument reliability of the GT1M was CV_intra = 2.9% and CV_inter = 3.5% for counts and CV_intra = 1.1% and CV_inter = 1.2% for steps. No batch effects were evident in the 50 GT1Ms. The Actigraph GT1M accelerometer demonstrated good reliability for measuring both counts and steps. However, the ability of the GT1M to consistently detect acceleration at a given acceleration and frequency condition varied widely. Future studies clarifying the filtering limitations and the threshold necessary to detect the occurrence of movement are warranted.  相似文献