Photon Mass and Very Long Baseline Interferometry

A relation between the photon mass, its frequency, $\nu$, and the deflection parameter, $\gamma$, determined by experimentalists (which characterizes the contribution of space curvature to gravitational deflection) is found. This amazing result allows us to conclude that the knowledge of the parameters $\nu$ and $\gamma$ is all we need to set up gravitational bounds on the photon mass. By considering as inputs the most recent measurements of the solar gravitational deflection of radio waves obtained via the Very Long Baseline Interferometry, upper bounds on the photon mass are estimated.Comment: Accepted for publication in International Journal of Modern Physics

Effects of Nutrient Availability and Other Elevational Changes on Bromeliad Populations and Their Invertebrate Communities in a Humid Tropical Forest in Puerto Rico

Nutrient inputs into tank bromeliads were studied in relation to growth and productivity, and the abundance, diversity and biomass of their animal inhabitants, in three forest types along an elevational gradient. Concentrations of phosphorus, potassium and calcium in canopy-derived debris, and nitrogen and phosphorus in phytotelm water, declined with increasing elevation. Dwarf forest bromeliads contained the smallest amounts of debris/plant and lowest concentrations of nutrients in plant tissue. Their leaf turnover rate and productivity were highest and, because of high plant density, they comprised 12.8and contained 3.3 t ha -1 of water. Annual nutrient budgets indicated that these microcosms were nutrient-abundant and accumulated \u3c 5dwarf forest, where accumulation was c. 25biomass/plant peaked in the intermediate elevation forest, and were positively correlated with the debris content/bromeliad across all forest types. Animal species richness showed a significant mid-elevational peak, whereas abundance was independent of species richness and debris quantities, and declined with elevation as forest net primary productivity declined. The unimodal pattern of species richness was not correlated with nutrient concentrations, and relationships among faunal abundance, species richness, nutrient inputs and environment are too complex to warrant simple generalizations about nutrient resources and diversity, even in apparently simple microhabitats

Pure red cell aplasia induced by epoetin zeta

Pure red cell aplasia (PRCA) may develop in patients with chronic kidney disease receiving erythropoiesis-stimulating agents (ESA). We report on a 72-year-old patient who developed hypo-proliferative anaemia unresponsive to ESA following the administration of epoetin zeta subcutaneously for 7 months. On the basis of severe isolated hypoplasia of the erythroid line in the bone marrow and high-titre neutralizing anti-erythropoietin antibodies (Ab), a diagnosis of Ab-mediated PRCA was made. Epoetin zeta was discontinued and the patient was given steroids. This was associated with anaemia recovery. To our knowledge this is the first PRCA case related to epoetin zeta

Effects of Hurricane Disturbance on Stream Water Concentrations and Fluxes in Eight Tropical Forest Watersheds of the Luquillo Experimental Forest, Puerto Rico

Stream water chemistry responds substantially to watershed disturbances, but hurricane effects have not been extensively investigated in tropical regions. This study presents a long-term (2.5-11 y) weekly record of stream water chemistry on eight forested watersheds (catchment basins) in the Luquillo Mountains of Puerto Rico. This includes a period before and at least 2 y after the disturbance caused by the 1989 Hurricane Hugo. Nitrate, potassium and ammonium concentrations increased after the hurricane and remained elevated for up to 2 y. Sulphate, chloride, sodium, magnesium and calcium showed smaller relative significant changes. Average stream water exports of potassium, nitrate and ammonium increased by 13.1, 3.6 and 0.54 kg ha -1 y -1 in the first post-hurricane year across all watersheds. These represent increases of 119, 182 and 102 of record. The increased stream outputs of potassium and nitrogen in the first 2 y post-hurricane are equivalent to 3of the hurricane-derived plant litter. Effects of hurricanes on tropical stream water potassium and nitrogen can be greater than those caused by canopy gaps or limited forest cutting, but less than those following large-scale deforestation or fire

VISUAL FLOW DOES NOT ALTER MUSCLE ACTIVITY DURING TREADMILL WALKING OR RUNNING

The current study examined the effect of visual flow (patterns of visual movement of surroundings) on muscle activity during treadmill walking and running. Participants (n=14 walked (1 -39 m-s4) and ran (2.78 msl) in visual flow and control conditions. Activity of the vastus medalis (VM), biceps fernoris (BF), gluteus maximus (GM ), gastrocnemius (GA), tibialis anterior (TA), erector spinae (ES), mtus abdominis (RA), and C4 paraspinal (C4) were assessed via electromyography (EMG) during each condition. Repeated Measures ANOVA revealed EMG differences (p < 0.05) between walking and running for RA, VM, GM, and BF. There were no differences in speeds for the other muscles, or across the visual conditions for any of the muscles. Visual flow does not alter muscle activity during walking or running

The effects of the frog Eleutherodactylus coqui on invertebrates and ecosystem processes at two scales in the Luquillo Experimental Forest, Puerto Rico

Determining the ubiquity of top-down control effects of predators on their prey and ecosystem processes is important for understanding community and ecosystem-level consequences that may result from predator loss. We conducted experiments at two spatial scales to investigate the effects of terrestrial frogs (Eleutherodactylus coqui) on aerial and litter invertebrates, plant growth and herbivory, and litter decomposition. At both scales, frogs reduced aerial invertebrates and leaf herbivory, but had no effect on litter invertebrates. At the smaller scale, frogs increased foliage production rates, measured as the number of new leaves and new leaf area produced, by 80% and decomposition rates by 20%. The influence of E. coqui on increasing primary productivity and decomposition rates at the smaller scale appeared to be a result of elimination and excretion rather than of controlling prey. While the results provide evidence for frogs controlling herbivorous prey at both scales, species effects on ecosystem processes were only detectable at the smaller scale. The results highlight the difficulties in conducting experiments at large spatial scales. The findings from this study imply that the loss of amphibians and other species of higher trophic levels may affect nutrient cycling rates in tropical forests

Redução dos desmatamentos na Amazônia: política agrícola ou ambiental?

bitstream/item/125042/1/Reducao.pdfApresentado na 3. Conferencia Internacional de Integração de Sistemas - ICSI'94, São Paulo, 1994. Publicado também em: HOMMA, A. K. O. (Ed.). Amazônia: meio ambiente e desenvolvimento agrícola. Brasília, DF: EMBRAPA-SPI; Belém, PA: EMBRAPA-CPATU, 1998. p. 119-141

Mitochondrial myopathy and comorbid major depressive disorder. effectiveness of dTMS on gait and mood symptoms

Background: Mitochondrial myopathies (MMs) often present with leukoencephalopathy and psychiatric symptoms, which do not respond to or worsen with psychiatric drugs. Case report: A 67-year-old woman with a 10-year history of probable chronic progressive external ophthalmoplegia, an MM, had drug-resistant, anxious-depressive symptoms. Since she had never had seizures, we proposed 20 sessions of deep transcranial magnetic stimulation (dTMS) for her depression. Surprisingly, besides the expected improvement of depression, we observed marked improvement of movement disorder that lasted as long as the patient was undergoing dTMS. She also improved her performance on neuropsychological tests of executive function and cognitive speed. Depressive symptom improvement was persistent, while anxiety symptoms recurred after the end of the sessions. Conclusions: dTMSmay be an alternative antidepressant strategy in patients withMMs, provided that they are free from seizures. The mechanism of improvement of motor disturbance may relate to dorsolateral prefrontal cortex stimulation and improved executive function and needs further investigation