37 research outputs found
Recommended from our members
The contribution of tropical cyclones to the atmospheric branch of Middle America's hydrological cycle using observed and reanalysis tracks
Middle America is affected by tropical cyclones (TCs) from the Eastern Pacific and the North Atlantic Oceans. We characterize the regional climatology (1998-2016) of the TC contributions to the atmospheric branch of the hydrological cycle, from May to December. TC contributions to rainfall are quantified using Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42 and TC tracks derived from three sources: the International Best Track Archive for Climate Stewardship (IBTrACS), and an objective feature tracking method applied to the Japanese 55-year and ERA-Interim reanalyses. From July to October, TCs contribute 10-30% of rainfall over the west and east coast of Mexico and central Mexico, with the largest monthly contribution during September over the Baja California Peninsula (up to 90%). TCs are associated with 40-60% of daily extreme rainfall (above the 95th percentile) over the coasts of Mexico. IBTrACS and reanalyses agree on TC contributions over the Atlantic Ocean but disagree over the Eastern Pacific Ocean and continent; differences over the continent are mainly attributed to discrepancies in TC tracks in proximity to the coast and TC lifetime. Reanalysis estimates of TC moisture transports show that TCs are an important moisture source for the regional water budget. TC vertically integrated moisture flux (VIMF) convergence can turn regions of weak VIMF divergence by the mean circulation into regions of weak VIMF convergence. We discuss deficiencies in the observed and reanalysis TC tracks, which limit our ability to quantify robustly the contribution of TCs to the regional hydrological cycle
Inflammatory response to the administration of mesenchymal stem cells in an equine experimental model: effect of autologous, and single and repeat doses of pooled allogeneic cells in healthy joints
Electrical stimulation of the auditory nerve: the effect of electrode position on neural excitation
Publisher’s permission requested and denied.Histological studies have shown that the Melbourne/Cochlear electrode array lies along the outer wall of the scala tympani and is therefore some distance from the residual VIIIth nerve elements. In order to investigate the influence of electrode position on neural excitation we systematically varied the position of the electrode array within the cat scala tympani while recording electrically evoked auditory brainstem responses (EABRs). Using both normal hearing and long-term deafened animals, we observed significant reductions in EABR thresholds as the electrode array was moved from the outer wall towards the modiolus. Further threshold reductions were observed when the array was placed underneath the osseous spiral lamina (OSL) close to the peripheral dendrites. These changes were independent of the bipolar inter-electrode separation, and were observed over a wide range of cochlear pathologies varying from normal to a moderate spiral ganglion cell loss. Interestingly, the one animal exhibiting extensive neural loss showed no correlation between EABR threshold and electrode position. There was also a general decrease in the gradient of the EABR input-output function as the electrode array was moved closer to the neural elements. This was, however, only statistically significant when the electrode was positioned adjacent to the peripheral dendrites. Significant reductions in EABR threshold were also observed as the inter-electrode spacing of the bipolar electrodes was increased. The gradient of the EABR input-output function also increased with increasing inter-electrode spacing, although again, this was only significant when the electrode array was positioned close to the neural elements.
The present results indicate that the optimum placement of a Melbourne/Cochlear electrode array is adjacent to the peripheral dendrites. However, such a site would be difficult to achieve in practice while minimizing insertion trauma. An array lying adjacent to the modiolus would be a safe alternative while ensuring a significant reduction in threshold compared with the existing site (outer wall). This placement should result in more localized neural excitation patterns, an increase in the number of bipolar electrodes available, together with an increase in their dynamic range. These changes may lead to further improvements in speech perception among cochlear implant patients
The influence of electrode geometry on the electrically evoked auditory brain stem response
The electrically-evoked auditory brainstem response (EABR) consists of a series of far-field potentials that reflect synchronous neural activity within the auditory brainstem in response to a transient electrical stimulus. The EABR appears relatively simply organized in terms of its amplitude and latency behaviour. The growth in amplitude of wave IV of the EABR, for example, reflects changes in the amplitude of the electrically-evoked VIII nerve compound action potential as a function of stimulus intensity. In addition, single unit population studies have shown a monotonic relationship between the growth in EABR amplitude and the number of nerve fibres being stimulated (Merzenich and White, 1977). The EABR can therefore, provide an insight into the response of the auditory nerve to electrical stimulation. We have used this technique to investigate the efficacy of electrical stimulation of the auditory nerve using a variety of stimulating electrode geometries
Simulating river discharge in a snowy region of Japan using output from a regional climate model
Snowfall amounts have fallen sharply along the eastern coast of the Sea of
Japan since the mid-1980s. Toyama Prefecture, located approximately in the
center of the Japan Sea region, includes high mountains of the northern
Japanese Alps on three of its sides. The scarcity of meteorological
observation points in mountainous areas limits the accuracy of hydrological
analysis. With the development of computing technology, a dynamical
downscaling method is widely applied into hydrological analysis. In this
study, we numerically modeled river discharge using runoff data derived by a
regional climate model (4.5-km spatial resolution) as input data to river
networks (30-arcseconds resolution) for the Toyama Prefecture. The five main
rivers in Toyama (the Oyabe, Sho, Jinzu, Joganji, and Kurobe rivers) were
selected in this study. The river basins range in area from 368 to 2720 km2. A numerical experiment using climate comparable to that at present
was conducted for the 1980s and 1990s. The results showed that seasonal
river discharge could be represented and that discharge was generally
overestimated compared with measurements, except for Oyabe River discharge,
which was always underestimated. The average correlation coefficient for
10-year average monthly mean discharge was 0.8, with correlation
coefficients ranging from 0.56 to 0.88 for all five rivers, whereas the
Nash-Sutcliffe efficiency coefficient indicated that the simulation accuracy
was insufficient. From the water budget analysis, it was possible to
speculate that the lack of accuracy of river discharge may be caused by
insufficient accuracy of precipitation simulation