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1.
Sensors (Basel) ; 24(4)2024 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-38400303

RESUMEN

Currently, basketball teams use inertial devices for monitoring external and internal workload demands during training and competitions. However, the intensity thresholds preset by device manufacturers are generic and not adapted for specific sports (e.g., basketball) and players' positions (e.g., guards, forwards, and centers). Using universal intensity thresholds may lead to failure in accurately capturing the true external load faced by players in different positions. Therefore, the present study aimed to identify external load demands based on playing positions and establish different intensity thresholds based on match demands in order to have specific reference values for teams belonging to the highest competitive level of Spanish basketball. Professional male players (n = 68) from the Spanish ACB league were monitored during preseason official games. Three specific positions were used to group the players: guards, forwards, and centers. Speed, accelerations, decelerations, impacts/min, and player load/min were collected via inertial devices. Two-step clustering and k-means clustering categorized load metrics into intensity zones for guards, forwards, and centers. Guards covered more distance at high speeds (12.72-17.50 km/h) than forwards and centers (p < 0.001). Centers experienced the most impacts/min (p < 0.001). Guards exhibited greater accelerations/decelerations, albeit mostly low magnitude (p < 0.001). K-means clustering allowed the setting of five zones revealing additional thresholds. All positions showed differences in threshold values (p < 0.001). The findings provide insights into potential disparities in the external load during competition and help establish position-specific intensity thresholds for optimal monitoring in basketball. These data are highly applicable to the design of training tasks at the highest competitive level.


Asunto(s)
Rendimiento Atlético , Baloncesto , Masculino , Humanos , Carga de Trabajo , Aceleración
2.
Sensors (Basel) ; 24(10)2024 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-38794099

RESUMEN

Basketball involves frequent high-intensity movements requiring optimal aerobic power. Altitude training can enhance physiological adaptations, but research examining its effects in basketball is limited. This study aimed to characterize the internal/external workload of professional basketball players during preseason and evaluate the effects of altitude and playing position. Twelve top-tier professional male basketball players (Liga Endesa, ACB; guards: n = 3, forwards: n = 5, and centers: n = 4) participated in a crossover study design composed of two training camps with nine sessions over 6 days under two different conditions: high altitude (2320 m) and sea level (10 m). Internal loads (heart rate, %HRMAX) and external loads (total distances covered across speed thresholds, accelerations/decelerations, impacts, and jumps) were quantified via wearable tracking and heart rate telemetry. Repeated-measures MANOVA tested the altitude x playing position effects. Altitude increased the total distance (+10%), lower-speed running distances (+10-39%), accelerations/decelerations (+25-30%), average heart rate (+6%), time in higher-intensity HR zones (+23-63%), and jumps (+13%) across all positions (p < 0.05). Positional differences existed, with guards accruing more high-speed running and centers exhibiting greater cardiovascular demands (p < 0.05). In conclusion, a 6-day altitude block effectively overloads training, providing a stimulus to enhance fitness capacities when structured appropriately. Monitoring workloads and individualizing training by playing position are important when implementing altitude training, given the varied responses.


Asunto(s)
Altitud , Baloncesto , Frecuencia Cardíaca , Carga de Trabajo , Humanos , Baloncesto/fisiología , Masculino , Frecuencia Cardíaca/fisiología , Adulto , Adulto Joven , Estudios Cruzados , Rendimiento Atlético/fisiología , Aceleración , Carrera/fisiología , Atletas
3.
Sensors (Basel) ; 24(3)2024 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-38339521

RESUMEN

Rice (Oryza sativa L.) is a staple cereal in the diet of more than half of the world's population. Within the European Union, Spain is a leader in rice production due to its climate and tradition, accounting for 26% of total EU production in 2020. The Valencian rice area covers around 15,000 hectares and is strongly influenced by biotic and abiotic factors. An important biotic factor affecting rice production is weeds, which compete with rice for sunlight, water and nutrients. The dominant weed in Spain is Echinochloa spp., although wild rice is becoming increasingly important. Rice cultivation in Valencia takes place in the area of L'Albufera de Valencia, which is a natural park, i.e., a special protection area. In this natural area, the use of phytosanitary products is limited, so it is necessary to use the minimum amount possible. Therefore, the objective of this work is to evaluate the possibility of using remote sensing effectively to determine the effectiveness of the application of the herbicide cyhalofop-butyl by drone for the control of Echinochloa spp. in rice crops in Valencia. The results will be compared with those obtained by using sterilisation machines (electric backpack sprayers) to apply the herbicide. To evaluate the effectiveness of the application, the reflectance obtained by the satellite sensors in the red and near infrared (NIR) wavelengths, as well as the normalised difference vegetation index (NDVI), were used. The remote sensing results were analysed and complemented by the number of rice plants and weeds per area, plant dry weight, leaf area, BBCH phenological state, SPAD index values, chlorophyll content and relative growth rate. Remote sensing is validated as an effective tool for determining the efficacy of an herbicide in controlling weeds applied by both the drone and the electric backpack sprayer. The weeds slowed down their development after the treatment. Depending on the phenological state of the crop and the active ingredient of the herbicide, these results are applicable to other areas with different climatic and environmental conditions.


Asunto(s)
Echinochloa , Herbicidas , Oryza , Herbicidas/farmacología , España , Tecnología de Sensores Remotos , Dispositivos Aéreos No Tripulados , Malezas
4.
Sensors (Basel) ; 22(1)2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-35009866

RESUMEN

In previous studies found in the literature speed (SP), acceleration (ACC), deceleration (DEC), and impact (IMP) zones have been created according to arbitrary thresholds without considering the specific workload profile of the players (e.g., sex, competitive level, sport discipline). The use of statistical methods based on raw data could be considered as an alternative to be able to individualize these thresholds. The study purposes were to: (a) individualize SP, ACC, DEC, and IMP zones in two female professional basketball teams; (b) characterize the external workload profile of 5 vs. 5 during training sessions; and (c) compare the external workload according to the competitive level (first vs. second division). Two basketball teams were recorded during a 15-day preseason microcycle using inertial devices with ultra-wideband indoor tracking technology and microsensors. The zones of external workload variables (speed, acceleration, deceleration, impacts) were categorized through k-means clusters. Competitive level differences were analyzed with Mann-Whitney's U test and with Cohen's d effect size. Five zones were categorized in speed (<2.31, 2.31-5.33, 5.34-9.32, 9.33-13.12, 13.13-17.08 km/h), acceleration (<0.50, 0.50-1.60, 1.61-2.87, 2.88-4.25, 4.26-6.71 m/s2), deceleration (<0.37, 0.37-1.13, 1.14-2.07, 2.08-3.23, 3.24-4.77 m/s2), and impacts (<1, 1-2.99, 3-4.99, 5-6.99, 7-10 g). The women's basketball players covered 60-51 m/min, performed 27-25 ACC-DEC/min, and experienced 134-120 IMP/min. Differences were found between the first and second division teams, with higher values in SP, ACC, DEC, and IMP in the first division team (p < 0.03; d = 0.21-0.56). In conclusion, k-means clustering can be considered as an optimal tool to categorize intensity zones in team sports. The individualization of external workload demands according to the competitive level is fundamental for designing training plans that optimize sports performance and reduce injury risk in sport.


Asunto(s)
Rendimiento Atlético , Baloncesto , Aceleración , Análisis por Conglomerados , Femenino , Humanos , Carga de Trabajo
5.
Sensors (Basel) ; 22(9)2022 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-35590988

RESUMEN

The general objective of this study was to identify the variation in heart rate (HR) of Portuguese skydivers during 6 moments in their first jump of the day, bearing in mind the variable level of experience. Thirty-one Portuguese skydivers, 28 men and 3 women, aged between 19 and 62, participated in the study, 12 had A and B licenses (less experienced) and 19 had C and D licences (more experienced). The instrument used to record the heart rate of the skydivers at the different moments of their first jump of the day was the WIMU PRO. A repeated measures analysis of variance was used to analyse HR at different moments in the jump and its relation with the variables level of experience. Bonferroni multiple comparisons were performed to study the importance of the differences observed in HR at the different moments. The effect size was evaluated with partial eta squared. The results showed that average HR in this group of skydivers was 130 bpm, in the different moments of the jump. HR increases from the value recorded at rest until the moment of jumping from the plane and opening the parachute, reaching the highest average at that moment, then decreasing until contact with the ground. Comparing the variable, we found that the less experienced had higher HR than the more experienced at all moments during the jump. Statistically significant differences were found at the different moments of the jump, regarding HR (Max: p < 0.001, ƞ2p = 0.820; Min: p < 0.001, ƞ2p = 0.821; AVG: p < 0.001, ƞ2p = 0.834) Level of experience with jumping moment interaction, we only verified differences related to HR Min (p = 0.007, ƞ2p = 0.056),. With regard to experience, the identified differences were not statistically significant. Skydiving triggers an acute adaptive cardiovascular response which is reflected in the increase in the HR, between the moment of boarding the plane and the moment at which the parachute opens, thereafter decreasing until contact with the ground. The most experienced parachutists recorded the highest HR at the moment of landing and the least experienced at the moment of free fall.


Asunto(s)
Aviación , Adulto , Fenómenos Biomecánicos , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Articulación de la Rodilla , Masculino , Persona de Mediana Edad , Portugal , Adulto Joven
6.
Sensors (Basel) ; 22(12)2022 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-35746216

RESUMEN

This study aimed to investigate how different strategies of task constraint manipulation impact physical and tactical demands in small-sided and conditioned games (SSCG). Ten recreational U-17 soccer players participated in this study (16.89 ± 0.11 years). We used different strategies of task manipulation to design two 4 vs. 4 SSCG: Structural SSCG and Functional SSCG. In Structural SSCG, pitch format and goal sizes were manipulated, while in Functional SSCG, players were allowed to kick the ball twice and at least 5 passes to shoot at the opponent's goal. Players participated in four Structural and Functional SSCG, of five minutes duration with a two-minute interval in between. Players' physical performance and tactical behavior were assessed using the WIMU PROTM inertial device. Structural SSCG stimulated players to cover more distance in sprinting (p = 0.003) and high-speed running (p < 0.001). Regarding tactical behavior, Structural SSCG stimulated players to explore game space better (p < 0.001). Moreover, Functional SSCG stimulated players to be closer to the ball, decreasing the effective playing space (p = 0.008). We conclude that these strategies of task constraint manipulation impact physical and tactical demands of the game.


Asunto(s)
Rendimiento Atlético , Carrera , Fútbol , Motivación , Rendimiento Físico Funcional
7.
Plant Cell Environ ; 44(5): 1642-1662, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33464573

RESUMEN

Adventitious roots (ARs) are produced from non-root tissues in response to different environmental signals, such as abiotic stresses, or after wounding, in a complex developmental process that requires hormonal crosstalk. Here, we characterized AR formation in young seedlings of Solanum lycopersicum cv. 'Micro-Tom' after whole root excision by means of physiological, genetic and molecular approaches. We found that a regulated basipetal auxin transport from the shoot and local auxin biosynthesis triggered by wounding are both required for the re-establishment of internal auxin gradients within the vasculature. This promotes cell proliferation at the distal cambium near the wound in well-defined positions of the basal hypocotyl and during a narrow developmental window. In addition, a pre-established pattern of differential auxin responses along the apical-basal axis of the hypocotyl and an as of yet unknown cell-autonomous inhibitory pathway contribute to the temporal and spatial patterning of the newly formed ARs on isolated hypocotyl explants. Our work provides an experimental outline for the dissection of wound-induced AR formation in tomato, a species that is suitable for molecular identification of gene regulatory networks via forward and reverse genetics approaches.


Asunto(s)
Ácidos Indolacéticos/metabolismo , Raíces de Plantas/fisiología , Brotes de la Planta/fisiología , Solanum lycopersicum/fisiología , Transporte Biológico , Ambiente , Gravitropismo/fisiología , Hipocótilo/fisiología
8.
Sensors (Basel) ; 21(10)2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-34063340

RESUMEN

The present study analyzed the multi-location external workload profile in basketball players using a previously validated test battery and compared the demands among anatomical locations. A basketball team comprising 13 semi-professional male players was evaluated in five tests (abilities/skills/tests): (a) aerobic, linear movement, 30-15 IFT; (b) lactic anaerobic, acceleration and deceleration, 16.25 m RSA (c) alactic anaerobic, curvilinear movement, 6.75 m arc (d) elastic, jump, Abalakov test (e) physical-conditioning, small-sided game, 10' 3 vs.3 10 × 15 m. PlayerLoadRT was evaluated at six anatomical locations simultaneously (interscapular line, lumbar region, knees and ankles) by six WIMU PROTM inertial devices attached to the player using an ad hoc integral suit. Statistical analysis was composed of an ANOVA of repeated measures and partial eta squared effect sizes. Significant differences among anatomical locations were found in all tests with higher values in the location nearer to ground contact (p < 0.01). However, differences between lower limb locations were only found in curvilinear movements, with a higher workload in the outside leg (p < 0.01). Additionally, high between-subject variability was found in team players, especially at lower limb locations. In conclusion, multi-location evaluation in sports movements will make it possible to establish an individual external workload profile and design specific strategies for training and injury prevention programs.


Asunto(s)
Rendimiento Atlético , Baloncesto , Aceleración , Masculino , Movimiento , Carga de Trabajo
9.
Sensors (Basel) ; 21(13)2021 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-34206600

RESUMEN

The external workload measured in one anatomical location does not determine the total load supported by the human body. Therefore, the purpose of the present study was to characterize the multi-location external workload through PlayerLoadRT of 13 semi-professional women's basketball players, as well as to analyze differences among anatomical locations (inter-scapulae line, lumbar region, 2× knee, 2× ankle) and laterality (left vs. right) during five tests that represent the most common movements in basketball-(a) linear locomotion, 30-15 IFT; (b) acceleration and deceleration, 16.25-m RSA (c) curvilinear locomotion, 6.75-m arc (d) jump, Abalakov test (e) small-sided game, 10' 3 vs. 3 10 × 15-m. Statistical analysis was composed of a repeated-measures t-test and eta partial squared effect size. Regarding laterality, differences were found only in curvilinear locomotion, with a higher workload in the outer leg (p < 0.01; ηp2 = 0.33-0.63). In the vertical profile, differences among anatomical locations were found in all tests (p < 0.01; ηp2 = 0.56-0.98). The nearer location to ground contact showed higher values except between the scapulae and lumbar region during jumps (p = 0.83; ηp2 = 0.00). In conclusion, the multi-location assessment of external workload through a previously validated test battery will make it possible to understand the individual effect of external workload in each anatomical location that depends on the type of locomotion. These results should be considered when designing specific strategies for training and injury prevention.


Asunto(s)
Baloncesto , Aceleración , Femenino , Humanos , Movimiento , Carga de Trabajo
10.
Sensors (Basel) ; 20(3)2020 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-32012864

RESUMEN

In this work, we present a bifocal Fresnel zone plate (BiFZP) capable of generating focusing profiles with two different foci. The performance of the BiFZP is demonstrated in the ultrasound domain, with a very good agreement between the experimental measurements and the finite element method (FEM) simulations. This lens becomes an appealing alternative to other dual-focusing lenses, in which the foci location can only be set at a limited range of positions, such as M-bonacci zone plates. Moreover, the variation of the operating frequency has also been analyzed, providing an additional dynamic control parameter in this type of lenses.

11.
J Strength Cond Res ; 34(10): 2920-2928, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30216248

RESUMEN

González-Espinosa, S, Antúnez, A, Feu, S, and Ibáñez, SJ. Monitoring the external and internal load under 2 teaching methodologies. J Strength Cond Res 34(10): 2920-2928, 2020-The purpose of this study was to analyze and compare the physical demands produced by the implementation of 2 sport teaching methods during a class and their relation with the learning achieved by the students. Two intervention programs were used to teach the sport of basketball, one based on the direct instruction (DI) method and the other on the tactical-game approach (TGA). The intervention programs were administered to 4 groups of students, 2 for each methodology, with 88 students participating in the study. A total of 10 practical sessions were given, as well as a pre-test and post-test. The practical sessions and the tests were recorded with an inertial system for monitoring and recording physical activity and movement in real time. Differences were found between the methodologies in the teaching sessions in the variables m·min, acc·min, PL·min, and HRmax (p < 0.000). In the assessment tests, there were also differences between both methodologies in the walk and sprint variables (p < 0.005). The results obtained from the analysis of the sessions using each methodology show that the TGA method obtained better results in the variables of external and internal loads than the DI methodology. The TGA methodology permitted a greater development of the students' physical fitness. Moreover, performance in play was not associated with the achievement of higher values in the results of external and internal load in the tests. The students trained with the TGA methodology recorded better performance indicators in the game. These results lead us to recommend physical education teachers to use a student-centered approach in their lessons because it improved both the students' physical fitness and their sports performance.


Asunto(s)
Rendimiento Atlético/fisiología , Baloncesto/fisiología , Frecuencia Cardíaca/fisiología , Educación y Entrenamiento Físico/métodos , Esfuerzo Físico/fisiología , Logro , Niño , Femenino , Humanos , Aprendizaje , Estudios Longitudinales , Masculino , Aptitud Física/fisiología
12.
J Strength Cond Res ; 34(5): 1227-1236, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-31809460

RESUMEN

Gómez-Carmona, CD, Bastida-Castillo, A, Rojas-Valverde, D, de la Cruz Sánchez, E, García-Rubio, J, Ibáñez, SJ, and Pino-Ortega, J. Lower-limb dynamics of muscle oxygen saturation during the back-squat exercise: effects of training load and effort level. J Strength Cond Res 34(5): 1227-1236, 2020-The aim of this study was to analyze the effect of strength training on lower limb muscle oxygenation. The sample consisted of 12 male subjects (22.4 ± 1.73 years; 1.81 ± 0.08 cm height and 77.76 ± 8.77 kg body mass). Six different strength training stimuli were analyzed, based on the training variables: load (60-75% 1 repetition maximum [1RM]) and level of effort (LE) (E1: 4 × 8 [20RM], E2: 4 × 12 [20RM], E3: 4 × 16 [20RM], E4: 4 × 4 [10RM], E5: 4 × 6 [10RM], and E6: 4 × 8 [10RM]) in the squat exercise up to 90° with a 2-second stop between repetitions to avoid the myotatic reflex. Oxygen saturation at the beginning of the series (SmO2start), oxygen saturation at the end of the series (SmO2stop), percentage of oxygen saturation loss (▽%SmO2), and reoxygenation time (SmO2recT) were assessed using a near-infrared spectroscopy device. In addition, the percentage of mean propulsive velocity loss (%MPVL) was recorded using a linear transducer. The results suggested an influence of LE and training load on muscle oxygenation. A greater LE was directly associated with SmO2recT (r = 0.864), ▽%SmO2 (r = 0.873), and %MPVL (r = 0.883) and inversely with SmO2stop (r = -0.871). When the same LE was used (E1 vs. E4, E2 vs. E5, and E3 vs. E6), it was found that the stimuli with a higher load had a lower SmO2recT, ▽%SmO2, and %MPVL and a higher SmO2stop. Muscle oxygen saturation was found to be minimal (%SmO2 = 0) in stimuli with a LE greater than 60% (E3 and E6). The SmO2 variables studied in the present research could be considered as an easier and more useful method for understanding skeletal muscle fatigue during resistance training.


Asunto(s)
Extremidad Inferior/fisiología , Fuerza Muscular/fisiología , Músculo Esquelético/fisiología , Oxígeno/metabolismo , Entrenamiento de Fuerza/métodos , Estudios Transversales , Humanos , Masculino , Fatiga Muscular , Postura , Adulto Joven
13.
J Sport Rehabil ; 29(6): 738-747, 2020 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-31629327

RESUMEN

OBJECTIVES: (1) To describe the fast Fourier transform (FFT) multijoint as monopodal postural stability measurement in well-trained athletes, (2) to compare the within-subject FFT between laterality, joints, and body segments, and (3) to establish the within- and between-subject relationship between joints. METHODS: Twelve national-level basketball players participated voluntarily in this investigation. The participants performed two 60-second repetitions of a monopodal stability test (1 repetition with each lower limb), separated by 3 minutes of active recovery. All tests were recorded by 4 WIMU PRO™ inertial devices located on the ankle, knee, lumbar spine, and thoracic spine. The main variable was total acceleration, where the FFT was applied. RESULTS: The higher instability results were found in the ankle and in the nondominant lower limb (dominant = 1.131 [0.122] a.u. (arbitrary units); nondominant = 1.141 [0.172] a.u). In the body segment analysis, the greater percentage of differences (%diff) were shown between lumbar spine and knee in the dominant (%diff = -2.989%; d = 0.87) and nondominant (%diff = -3.243%; d = 0.90) lower limb. Finally, very large between-subjects variability was found in all joints and body segments. CONCLUSIONS: The described protocol is proposed for monopodal postural stability assessment, being useful to provide information about the stability of joints and the body segment between joints. Besides, a within-subject analysis is recommended, and the FFT calculation will enable a linear analysis of each test.


Asunto(s)
Acelerometría/métodos , Atletas , Equilibrio Postural/fisiología , Aceleración , Acelerometría/instrumentación , Adulto , Baloncesto , Humanos , Masculino , Tecnología Inalámbrica , Adulto Joven
14.
Plant Physiol ; 176(2): 1709-1727, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29233938

RESUMEN

Body regeneration through formation of new organs is a major question in developmental biology. We investigated de novo root formation using whole leaves of Arabidopsis (Arabidopsis thaliana). Our results show that local cytokinin biosynthesis and auxin biosynthesis in the leaf blade followed by auxin long-distance transport to the petiole leads to proliferation of J0121-marked xylem-associated tissues and others through signaling of INDOLE-3-ACETIC ACID INDUCIBLE28 (IAA28), CRANE (IAA18), WOODEN LEG, and ARABIDOPSIS RESPONSE REGULATORS1 (ARR1), ARR10, and ARR12. Vasculature proliferation also involves the cell cycle regulator KIP-RELATED PROTEIN2 and ABERRANT LATERAL ROOT FORMATION4, resulting in a mass of cells with rooting competence that resembles callus formation. Endogenous callus formation precedes specification of postembryonic root founder cells, from which roots are initiated through the activity of SHORT-ROOT, PLETHORA1 (PLT1), and PLT2. Primordia initiation is blocked in shr plt1 plt2 mutant. Stem cell regulators SCHIZORIZA, JACKDAW, BLUEJAY, and SCARECROW also participate in root initiation and are required to pattern the new organ, as mutants show disorganized and reduced number of layers and tissue initials resulting in reduced rooting. Our work provides an organ regeneration model through de novo root formation, stating key stages and the primary pathways involved.


Asunto(s)
Arabidopsis/genética , Reprogramación Celular , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Transducción de Señal , Arabidopsis/crecimiento & desarrollo , Regulación del Desarrollo de la Expresión Génica , Modelos Biológicos , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Regeneración
15.
Sensors (Basel) ; 19(18)2019 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-31514385

RESUMEN

A method of detecting dielectric objects hidden behind an opaque barrier located on a reflective background, based on the distortion of interference fringes, is proposed in this article. Experiments conducted in the millimeter wavelength range demonstrated the effectiveness of the method under consideration, which does not require a holographic image reconstruction. Such a system can be classified as contour imaging.

16.
Sensors (Basel) ; 19(2)2019 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-30658500

RESUMEN

The image performance of acoustic and ultrasound sensors depends on several fundamental parameters such as depth of focus or lateral resolution. There are currently two different types of acoustic diffractive lenses: those that form a diffraction-limited spot with a shallow depth of focus (zone plates) and lenses that form an extended focus (quasi-Bessel beams). In this paper, we investigate a pupil-masked Soret zone plate, which allows the tunability of a normalized angular spectrum. It is shown that the depth of focus and the lateral resolution can be modified, without changing the lens structure, by choosing the size of the pupil mask. This effect is based on the transformation of spherically-converging waves into quasi-conical waves, due to the apodization of the central part of the zone plate. The theoretical analysis is verified with both numerical simulations and experimental measurements. A Soret zone plate immersed in water with D/2F = 2.5 and F = 4.5 λ changes its depth of focus from 2.84 λ to 5.9 λ and the lateral resolution increases from 0.81 λ to 0.64 λ at a frequency of 250 kHz, by modifying the pupil mask dimensions of the Soret zone plate.

17.
Sensors (Basel) ; 17(7)2017 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-28737674

RESUMEN

The focusing capabilities of a pinhole zone plate lens are presented and compared with those of a conventional Fresnel zone plate lens. The focusing properties are examined both experimentally and numerically. The results confirm that a pinhole zone plate lens can be an alternative to a Fresnel lens. A smooth filtering effect is created in pinhole zone plate lenses, giving rise to a reduction of the side lobes around the principal focus associated with the conventional Fresnel zone plate lens. The manufacturing technique of the pinhole zone plate lens allows the designing and constructing of lenses for different focal lengths quickly and economically and without the need to drill new plates.

18.
Sensors (Basel) ; 17(12)2017 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-29206137

RESUMEN

The focusing properties of Fresnel Zone Plates (FZPs) against frequency are analyzed in this work. It is shown that the FZP focal length depends almost linearly on the operating frequency. Focal depth and focal distortion are also considered, establishing a limit on the frequency span at which the operating frequency can be shifted. An underwater FZP ultrasound focusing system is demonstrated, and experimental results agree with the theoretical analysis and simulations.

19.
J Funct Morphol Kinesiol ; 9(1)2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38535415

RESUMEN

The unprecedented COVID-19 health crisis severely disrupted global sports in 2020, prompting lengthy suspensions followed by resumed competitions under abnormal behind-closed-doors conditions without fans. These disruptions necessitated tactical adaptations by coaches and teams, attempting to still achieve successful outcomes. This study investigates the pandemic's impacts on performance metrics and indicators within Spanish professional soccer. Utilizing systematic notational analysis, 760 match cases from the 2019-2020 La Liga season were examined, comprising 27 matchdays from the pre-COVID context and 11 after resumption. Multivariate tests identified significant pre/post differences and interactions for various technical indicators including shots, cards, corners, and offside calls. The pandemic was associated with a reduction from 12 to just 5 identifiable playing styles, suggestive of increased conservatism featuring more passive play, limited attacking depth, and horizontal ball movement. Such tactical changes appear provoked by condensed fixture scheduling post-lockdown, the lack of supportive crowds, and compromised player fitness/recovery. By quantifying these COVID-precipitated changes, the analysis provides tangible evidence for coaches to make informed adjustments in training and preparation for functioning effectively in disrupted environments. The findings emphasize that versatility and flexibility will be vital to optimize performance during times of unprecedented uncertainty.

20.
Mar Environ Res ; 199: 106604, 2024 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-38908113

RESUMEN

The edible chiton Chiton articulatus is a commercially important mollusk found in the rocky intertidal zones of the Mexican tropical Pacific. Despite the intense harvesting in Acapulco Bay, Mexico, knowledge of its growth patterns is limited, hindering the development of effective management strategies. This study investigated the growth dynamics of C. articulatus using a multi-model inference approach based on size structure data collected in four sampling periods covering four decades. Results revealed continuous recruitment throughout the year, contributing to population resilience. The species exhibited growth plasticity, highlighting its adaptive potential. We found complex temporal patterns influenced mainly by climatic events. The El Niño event sowed higher growth rates and lower asymptotic length, while La Niña events showed the opposite pattern. This research provides insights into the growth dynamics of C. articulatus, highlighting the need for holistic management strategies for this commercially important species in the face of environmental change.

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