Variation in movement: Multiple locomotor gaits in neotropical harvestmen

Navigation of complex environments is crucial for animals to find food, mates and/or shelter and to escape enemies. In order to move successfully in variable conditions, many animals have evolved the ability to switch between several patterns of locomotion or gaits. Here, we describe and differentiate between putative locomotor gaits in the harvestman, an arachnid that uses a hexapod-like alternate tripod gait. We recorded Neotropical harvestmen of the genus Prionostemma moving across a flat surface using high-speed video. We reconstructed three-dimensional trajectories and associated kinematics and found four different locomotor gaits: running, stotting, bobbing and walking. Gaits differed in their performance and postural kinematics, body trajectory, gait diagrams and/or kinetic and potential energy exchange. Our approach points out the importance of using multiple kinematic features to differentiate gaits. The use of a specific gait was not predicted by leg length, body area or sex. We propose testable hypotheses regarding the function of each gait and the factors that drive the evolution of different gaits. Ultimately, the diversity of locomotory gaits can allow animals to respond to different environmental challenges and contexts

FACTORS AFFECTING THE PROFITABILITY OF GOLF COURSES IN GEORGIA

Land Economics/Use,

Effect of different micro-algae mixtures and rations in hatchery broodstock conditioning of the mussel Mytilus galloprovincialis.

Reproduction of the blue mussel Mytilus galloprovincialis in wild populations follows seasonal changes of environmental factors such as food availability.The aim of this experiment was to analyse the effects of three conditioning diets on the maturation and development of M. galloprovincialis. We experimented three different algae-based treatments: two Non-Tetraselmis (NT) groups and one Tetraselmis (TS) group. Those in the NT groups received a mixture of Isochrysis galbana (clon T-Iso) and Chaetoceros sp. (1:1, based on cell volume). Those in the TS group received Isochrysis sp. (T-Iso), Chaetoceros sp., and Tetraselmis suecica (1:1:1, based on cell volume). Mussels in the NT-1, NT-2 and TS groups received, respectively, 1%, 2% and 2% of the mussels dry weight (MDW) based in algae dry weight (ADW) a day. After 2 months of conditioning, significant changes between wild mussels and the NT-1 group were not detected either in condition index (CI) value or in gonad stadia percentages. On the opposite, after conditioning CI values of mussels having received 2 % ration were higher than those of wild populations and NT-1 group, and ripe female percentage was higher in the TS group than in the NT-2 group. As a conclusion, this study demonstrates that for M. galloprovincialis conditioning, 1% of the MDW in ADW is not enough, and that a varied diet is more suitable.This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.La reproducci&oacute;n del mejill&oacute;n Mytilus galloprovincialis en las poblaciones naturales sigue los cambios estacionales de factores ambientales como la disponibilidad de comida. El objetivo de este experimento fue analizar los efectos de tres dietas de acondicionamiento en la maduraci&oacute;n y el desarrollo de M. galloprovincialis. Para ello, se experimentaron tres tratamientos diferentes a base de microalgas: dos grupos sin la microalga Tetraselmis suecica (NT) y un tercero con esta microalga (TS). Los mejillones de los grupos NT recibieron una mezcla de Isochrysis galbana (clon T-Iso) y Chaetoceros sp. (1:1, basado en el volumen celular). Los del grupo de TS recibido I. galbana (clon T-Iso), Chaetoceros sp., y T. suecica (1:1:1, basado en el volumen celular). Los ejemplares de los grupos NT-1, NT-2 y TS recibieron, respectivamente, 1%, 2% y 2% del peso seco de la masa corporal (PSM) basado en el peso seco del fitoplancton (PSF) al d&iacute;a. Despu&eacute;s de 2 meses de acondicionamiento no se detectaron diferencias significativas en el valor del &iacute;ndice de condici&oacute;n (IC) ni en los porcentajes de estadios de madurez gonadal entre los mejillones del medio natural y el grupo NT-1. Sin embargo, despu&eacute;s del acondicionamiento valores del IC de los mejillones que recibieron el 2% de raci&oacute;n fueron superiores a los de las poblaciones del medio natural y el grupo NT-1. Adem&aacute;s, el porcentaje de hembras maduras fue mayor en el grupo TS que en el grupo NT-2. Como conclusi&oacute;n, este estudio demuestra que para el acondicionamiento de M. galloprovincialis un 1% de la PSM en PSF no es suficiente, y que una dieta variada es m&aacute;s adecuada.Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional). www.juntadeandalucia.es / agriculturaypesca / IFAPA / ecoaqua. &nbsp;</p

ANÁLISIS DE LAS CAPACIDADES DE ABSORCIÓN COMO DETERMINANTE CLAVE PARA LA COMPETITIVIDAD EN LAS PYME´S CAMARONÍCOLAS EN EL LITORAL DEL NORTE DE SINALOA

El presente artículo tiene como propósito evaluar las capacidades de absorción de conocimiento (CapAb) –Adquisición, Asimilación, Transformación y Explotación– en las PYME´s camaronícolas situadas en el litoral norte del estado de Sinaloa y examinar la relación existente entre sus principales dimensiones, coadyuvando en la competitividad de estas unidades de producción. Para ello se realizó una investigación de carácter empírico sobre una población de 71 granjas de las cuales fueron encuestadas 58 granjas acuícolas. Diseñándose un instrumento de medición (cuestionario) que permitió obtener información de primera mano en base a la percepción de los empresarios, con el fin de realizar una medición en las distintas dimensiones de la capacidad de absorción de conocimiento. Se evidencia una relación significativa entre las distintas capacidades de absorción y la competitividad de acuerdo al tamaño de las PYME´s estudiadas. La presente investigación aporta a la literatura científica un análisis empírico con soporte teórico al evidenciar el papel que representa hoy en día las capacidades de absorber conocimiento científico y tecnológico contribuyendo en la competitividad de las empresas, sobre un sector primario poco estudiado hasta este momento en esta línea de investigación. Palabras clave: Capacidad de Absorción, Competitividad, Camaronicultura, Sinaloa

¿Está el manejo comunitario de los recursos naturales inherentemente ligado a la resiliencia? Análisis de la comunidad de Santiago Comaltepec (México)

The sustainable management of forests is a current pressing need. Many communities around the world manage common pool forests and base their livelihoods on forest products. The communitybased management of natural resources approach has been often considered as a suitable approach to govern the commons. However, the application of these principles does not simply lead to harmonise development and conservation. We explore the links between community-based management of natural resources and social-ecological resilience in a Mexican indigenous community by: 1) analysing the trade-offs between environmentally sound forest management and socio-economic sustainability; 2) identifying the local strategies to face local, national and international challenges and analysing how they contribute to the socialecological resilience; and 3) reflecting about how the current situation might affect future social-ecological resilience. The results showed that land and forests are sustainably managed from an environmental perspective, but current social and economic pressures, within and outside the community, represent a serious threat to the traditional common management and sustainability cultureEl manejo sostenible de los bosques es hoy día más urgente que nunca. A nivel global existen muchos bosques gestionados por comunidades que dependen de ellos para su supervivencia. El manejo comunitario de recursos naturales es considerado como un enfoque adecuado para la gestión de bienes comunes. Sin embargo, la aplicación de estos principios no necesariamente ha conseguido aunar los principios de conservación de la naturaleza y desarrollo de las comunidades que realizan este manejo. En este artículo se analizan las relaciones entre la gestión comunitaria de los recursos naturales y la resiliencia socioecológica en una comunidad indígena mejicana. Para ello: 1) se exploran las relaciones entre gestión ambientalmente sostenible del bosque y sostenibilidad socioeconómica; 2) se identifican las estrategias locales frente a desafíos locales, nacionales e internacionales y se analiza como las mismas contribuyen a la resiliencia socioecológica y 3) se reflexiona sobre las principales amenazas a esta resiliencia socioecológica. Los resultados muestran que en la comunidad se está haciendo un manejo ambientalmente sostenible, pero que las actuales presiones sociales y económicas representan una seria amenaza al manejo tradicional colectivo y a la cultura de la sostenibilidad existente en la comunida

Fodder and Grain Yield in Native Maize (Zea mays L.)

The objective of the present study was to quantify in 7 varieties of native or landrace corn (Zea mays L): grain yield, biomass, stubble and leaf: stem index; as well as the relationship between biomass, stubble and plant height. .Design / methodology / approach: The treatments consisted in the sowing of seven cultivars of native corn (Zea mays L.). The experimental design was randomized blocks with four repetitions. The height of the plant, total biomass, its accumulation in stem, sheets, bracts, cob, grain and stubble (stem biomass + sheets + bracts + cob) were evaluated. An analysis of variance, the Tukey mean comparison test, and a regression analysis were applied. Results: Significant differences were found between native corn cultivars for the variables under study. The outstanding ones were Yellow from Ixtenco, followed in terms of biomass and stubble by Blanco-ancho from Texcoco, Blanco and Rojo from Ixtenco. The height of the plant determined the biomass in 67% and the stubble in 77%. Study limitations / implications: The trends found may vary depending on the native cultivars studied and their management. Findings / conclusions: In the study region, there are differences between native maize cultivars for the agronomic characteristics evaluated. In relation to grain yield, biomass and stubble, the cultivar Amarillo from Ixtenco was the outstanding one, followed by Blanco-ancho from Texcoco, Blanco and Rojo from Ixtenco. The height of the plant determined in 67% and 77% the amount of stubble and biomass.Objective: To quantify the grain yield, biomass, crop stubble, and leaf:stalk index in seven varieties of maize (Zea mays L.), as well as the relationship between biomass, stubble, and plant height. Design/Methodology/Approach: The process consisted in planting seven genotypes of native maize (Zea mays L.). The experimental design comprised randomized blocks with four repetitions. The plant’s height, total biomass, its accumulation in stalk, leaf, husk, cob, grain, and stubble (biomass of stalk?leaf?husk?cob) were evaluated. A varianceanalysis, the Tukey means comparison test, and a regression analysis were applied. Results: Significant differences were found between the native maize genotypes. Notable cases were the Ixtenco Yellow, followed in terms of biomass and stubble by the Texcoco White-Wide, then the Ixtenco White and Red. The plant height determined biomass in 67% and stubble in 77%. Study Limitations/Implications: The tendencies found could vary depending on the native cultivars studied and their management. Findings/Conclusions: In the study region, there are differences between native maize cultivars for the agronomic characteristics evaluated. With respect to the yield of grain, biomass, and stubble, the Ixtenco Yellow cultivar was outstanding, followed by the Texcoco White-Wide, and Ixtenco White and Red. The plant height determined biomass in 67%, and stubble quantity in 77%

A model of impairment and functional limitation in rheumatoid arthritis

BACKGROUND: We have previously proposed a theoretical model for studying physical disability and other outcomes in rheumatoid arthritis (RA). The purpose of this paper is to test a model of impairment and functional limitation in (RA), using empirical data from a sample of RA patients. We based the model on the disablement process framework. METHODS: We posited two distinct types of impairment in RA: 1) Joint inflammation, measured by the tender, painful and swollen joint counts; and 2) Joint deformity, measured by the deformed joint count. We hypothesized direct paths from the two impairments to functional limitation, measured by the shirt-button speed, grip strength and walking velocity. We used structural equation modeling to test the hypothetical relationships, using empirical data from a sample of RA patients recruited from six rheumatology clinics. RESULTS: The RA sample was comprised of 779 RA patients. In the structural equation model, the joint inflammation impairment displayed a strong significant path toward the measured variables of joint pain, tenderness and swelling (standardized regression coefficients 0.758, 0.872 and 0.512, P ≤ 0.001 for each). The joint deformity impairment likewise displayed significant paths toward the measured upper limb, lower limb, and other deformed joint counts (standardized regression coefficients 0.849, 0.785, 0.308, P ≤ 0.001 for each). Both the joint inflammation and joint deformity impairments displayed strong direct paths toward functional limitation (standardized regression coefficients of -0.576 and -0.564, respectively, P ≤ 0.001 for each), and explained 65% of its variance. Model fit to data was fair to good, as evidenced by a comparative fit index of 0.975, and the root mean square error of approximation = 0.058. CONCLUSION: This evidence supports the occurrence of two distinct impairments in RA, joint inflammation and joint deformity, that together, contribute strongly to functional limitations in this disease. These findings may have implications for investigators aiming to measure outcome in RA

A pure Dirac's canonical analysis for four-dimensional BF theories

We perform Dirac's canonical analysis for a four-dimensional $BF$ and for a generalized four-dimensional $BF$ theory depending on a connection valued in the Lie algebra of SO(3,1). This analysis is developed by considering the corresponding complete set of variables that define these theories as dynamical, and we find out the relevant symmetries, the constraints, the extended Hamiltonian, the extended action, gauge transformations and the counting of physical degrees of freedom. The results obtained are compared with other approaches found in the literature.Comment: Submitted to Journal of Physics A, Mathematical and Theoretica