5,216 research outputs found
OPTIMAL REGULATION AND GROWTH IN A NATURAL-RESOURCE-BASED ECONOMY
This paper develops a two-sector model for a renewable natural resource based economy. Pareto efficient results show the optimal harvesting rate that allows for sustained long-run optimal growth, which is upper-bounded by the biological rate of reproduction. Regulation prevents from resource over-exploitation and exhaustion which arise under open access. The Ramsey policy allowing the competitive economy to reach the first-best solution, leads the government to tax harvesting activity from firms and distribute the receipts among households. In the short-run the tax is variable. In the long-run, the lower the intrinsic rate of reproduction the higher the constant unit tax on the resource use.Natural Resources, Efficiency, Open Access, Ramsey Regulation, Growth.
Effects of 8 weeks strength training on vertical jump performance in elite male volleyball players during the in-season
Relationship of pull-up repetitions to maximal and relative lat-pull strength in trained athletes.
Efectos de un entrenamiento de fuerza de corta duración sobre la capacidad de salto vertical en jugadores de voleibol de elite durante la temporada
The aim of this study was to describe the effects of 6 weeks of combined strength and jump training which incorporated modera
te loads and
high intensity contractions on the vertical jump ability (VJ), loaded jumps and velocity of execution in full squat in a group
of professional male
volleyball players during the competition season. It was hypothesized that the VJ improved by cross combined strength and jump
training both
characterized by high velocity of execution (>1m/s). The participants in this study were twelve players who competed in the fir
st national division of
the Spanish National League during the 2011-2012 season. The neuromuscular performance was estimated by unloaded (CMJ) and load
ed
countermovement jumps (CMJ
loaded
) height (cm); and by velocity of displacement in the concentric phase of full squat (FS) (m/s). There was a
significant increase in CMJ and CMJ
loaded
after 6-week of training (5%, p<0.01; and 5.7%, p<0.05; respectively). These changes were accompanied by
a small and moderate value of Effect Size (0.47, and 0.67; respectively). No significant differences were observed for velocity
of displacement in FS.
The linear correlation analysis showed a single moderate correlation statistically significant between the changes in CMJ-CMJ
loaded
and CMJ-FS (r=0.62
and r=0.59, p<0.05; respectively). Albeit speculative, our results suggest that the use of moderate loads could be enough to im
prove the vertical jump
performance, since in our study a load equivalent to 60% 1RM in the FS was not exceeded and jumping exercises were performed wi
th light loads.El objetivo de este estudio fue describir los efectos de 6 semanas de entrenamiento combinado de fuerza y salto, el cual incorpora cargas
moderadas e intensidades de contracción altas, sobre la capacidad de salto vertical, saltos con cargas y la velocidad de ejecución en el ejercicio de sentadilla
en un grupo de jugadores profesionales de voleibol durante la temporada de competición. Se estableció la hipótesis de que el sa
lto vertical mejoro por el
uso combinado de entrenamiento de fuerza y salto, ambos caracterizados por una alta velocidad de ejecución (>1m/s). El rendimie
nto neuromuscular fue
estimado por la altura (cm) del salto sin cargas (CMJ), salto con cargas (CMJ
loaded
), y por la velocidad (m/s) de desplazamiento en la fase concéntrica en
la sentadilla completa (FS). Tuvo lugar un incremento significativo en CMJ y CMJ
loaded
después de 6 semanas de entrenamientos (5%, p<0.01; y 5.7%,
p<0.05; respectivamente). Estos cambios fueron acompañados por un valor de Tamaño del Efecto pequeño y moderado (0.47, and 0.67
; respectivamente). No se observaron diferencias significativas en la velocidad de desplazamiento en FS. El análisis de correlación lineal
mostró una correlación
moderada estadísticamente significativa entre los cambios en CMJ-CMJ
loaded
y CMJ-FS (r=0.62; y r=0.59, p<0.05; respectivamente). Aunque algo
especulativo, nuestros resultados sugieren que el uso de cargas moderadas podría ser suficiente para mejorar el rendimiento del
salto vertical, ya que en
nuestro estudio no se excedió una carga equivalente al 60% de 1RM en FS y los ejercicios de saltos también fueron realizados con cargas ligeras
An approximation to the prediction of the summery emergence of "Ochlerotatus caspius" (Diptera: Culicidae) based on the relationship between degree-days accumulations and adult captures
Ochlerotatus caspius (Pallas) (Diptera, Culicidae) es el culícido más abundante durante el verano en las marismas de Huelva. Este estudio demuestra que la relación entre capturas de adultos, convertidas en probit, y la acumulación de temperatura o número de días-grado, convenientemente adaptada mediante a una transformación logarítmica, muestra ser signifi cativamente lineal para cada generación de este mosquito a lo largo de cada verano. Además, si se procesan todos los datos disponibles de todos los años considerados en el estudio se obtiene una alta correlación lineal y, en consecuencia, las ecuaciones resultantes poseen valor predictivo. Los resultados de la validación de los pronósticos que se extraen de las rectas de regresión log-probit, permiten que se puedan considerar estas rectas como una herramienta más de cara a aumentar la efi cacia de los programas de control integrado que se llevan a cabo en esta zona.Predicción de la emergencia estival de Ochlerotatus caspius (Diptera:
Culicidae) basada en la relación entre la acumulación de días-grado y
la captura de adultos.
Ochlerotatus caspius (Pallas) (Diptera, Culicidae) es el culícido más
abundante durante el verano en las marismas de Huelva. Este estudio
demuestra que la relación entre capturas de adultos, convertidas en
probit, y la acumulación de temperatura o número de días-grado, convenientemente adaptada mediante a una transformación logarítmica,
muestra ser signifi cativamente lineal para cada generación de este
mosquito a lo largo de cada verano. Además, si se procesan todos
los datos disponibles de todos los años considerados en el estudio se
obtiene una alta correlación lineal y, en consecuencia, las ecuaciones
resultantes poseen valor predictivo. Los resultados de la validación de
los pronósticos que se extraen de las rectas de regresión log-probit,
permiten que se puedan considerar estas rectas como una herramienta
más de cara a aumentar la efi cacia de los programas de control integrado
que se llevan a cabo en esta zona
One- and two-photon scattering from generalized V-type atoms
The one- and two-photon scattering matrix S is obtained analytically for a
one-dimensional waveguide and a point-like scatterer with N excited levels
(generalized V -type atom). We argue that the two-photon scattering matrix
contains sufficient information to distinguish between different level
structures which are equivalent for single-photon scattering, such as a V -atom
with N = 2 excited levels and two two-level systems. In particular, we show
that the scattering with the V -type atom exhibits a destructive interference
effect leading to two-photon Coupled-Resonator-Induced Transparency, where the
nonlinear part of the two-photon scattering matrix vanishes when each incident
photon fulfills a single-photon condition for transparency
Single photons by quenching the vacuum
Heisenberg's uncertainty principle implies that the quantum vacuum is not
empty but fluctuates. These fluctuations can be converted into radiation
through nonadiabatic changes in the Hamiltonian. Here, we discuss how to
control this vacuum radiation, engineering a single-photon emitter out of a
two-level system (2LS) ultrastrongly coupled to a finite-band waveguide in a
vacuum state. More precisely, we show the 2LS nonlinearity shapes the vacuum
radiation into a nonGaussian superposition of even and odd cat states. When the
2LS bare frequency lays within the band gaps, this emission can be well
approximated by individual photons. This picture is confirmed by a
characterization of the ground and bound states, and a study of the dynamics
with matrix product states and polaron Hamiltonian methods.Comment: 9 pages, 10 figure
The baroque artist Peter Rellins: review of his life and his work
Pedro Rellins (h. 1676-1728) fue un escultor y retablista, nacido en la actual Holanda, que desarrolló su actividad en Sanlúcar de Barrameda (Cádiz), ciudad a la que se trasladó siendo aún niño. En este artículo se hace un repaso por la historiografía que ha tratado al artista, se profundiza en los nuevos datos biográficos emanados de su expediente matrimonial y se aportan novedades sobre su obra.Pedro Rellins (c. 1676-1728) was a sculptor and architect of altarpieces, born in the current Netherlands, who worked in Sanlucar de Barrameda (Cadiz), city to which moved still a child. In this article we review the historiography that has studied the artist, we delve into the new biographical details of your marriage certificate and we bring news about his work
Determinant factors of pull up performance in trainedathletes
Aim: to investigate the relationship among pull up and lat pull exercises and differentanthropometric dimensions in trained athletes. Methods: twenty-five males were evaluated for maximum number of pull ups, one-repetitionmaximum lat pull (1RM Lat Pull), lat pull repetitions at 80% 1RM (Lat Pull at 80% 1RM), latpull repetitions at a load equivalent to body mass (Lat Pull at BM-load), and differentanthropometric variables. Furthermore, the subjects were divided in higher (HPG, n = 12) andlower pull up performance (LPG, n = 13) to compare the differences in the variables analyzedbetween both levels. Results: pull ups were significantly correlated with Lat Pull at BM-load (r = .62, P < .01) butneither with 1RM Lat Pull (r = .09) nor with Lat Pull at 80% 1RM (r = -.15). Pull ups showed asignificant (P < .05) negative relationship with body mass (BM, r = -.55), lean body mass(LBM, r = -.51), and fat mass (FM, r = -.52), while BM and LBM were significantly correlatedwith 1RM Lat Pull (r = .55, P < .05). HPG showed significantly (P < .05) lower BM (0/3/97%),FM (1/3/97%) and LBM (1/4/95%) than LPG. Furthermore, HPG attained significantly (P < .05– .001) greater performance in Lat Pull at BM-load (100/0/0%) and 1RM Lat Pull•BM-1(96/3/2%) than LPG. Conclusion: these findings suggest that pull up and lat pull exercises have common elements.Moreover, the anthropometric dimensions seem to influence differently on both exercises,depending on the strength indicator evaluated
Plant Growth Promotion and Biocontrol of Pythium ultimum by Saline Tolerant Trichoderma Isolates under Salinity Stress
This present study evaluates three isolates of Trichoderma as plant growth promoting or biological control agents: Trichoderma aggressivum f. sp. europaeum, Trichoderma saturnisporum, and the marine isolate obtained from Posidonia oceanica, Trichoderma longibrachiatum. The purpose is to contribute to an overall reduction in pesticide residues in the fruit and the environment and to a decrease in chemical fertilizers, the excess of which aggravates one of the most serious abiotic stresses, salinity. The tolerance of the different isolates to increasing concentrations of sodium chloride was evaluated in vitro, as well as their antagonistic capacity against Pythium ultimum. The plant growth promoting capacity and effects of Trichoderma strains on the severity of P. ultimum on melon seedlings under saline conditions were also analysed. The results reveal that the three isolates of Trichoderma, regardless of their origin, alleviate the stress produced by salinity, resulting in larger plants with an air-dry weight percentage above 80% in saline stress conditions for T. longibrachiatum, or an increase in root-dry weight close to 50% when T. aggressivum f. sp. europaeum was applied. Likewise, the three isolates showed antagonistic activity against P. ultimum, reducing the incidence of the disease, with the highest response found for T. longibrachiatum. Biological control of P. ultimum by T. aggressivum f. sp. europaeum and T. saturnisporum is reported for the first time, reducing disease severity by 62.96% and 51.85%, respectively. This is the first description of T. aggressivum f. sp. europaeum as a biological control agent and growth promoter. The application of these isolates can be of enormous benefit to horticultural crops, in both seedbeds and greenhouses
- …