Changes in heart rate and heart rate variability as a function of age in Thoroughbred horses.

We investigated changes in heart rate (HR) and HR variability as a function of age in newborn foals to old Thoroughbred horses. Experiments were performed on a total of 83 healthy and clinically normal Thoroughbred horses. Resting HR decreased with age from birth. The relationship between age and HR fit the equation Y=48.2X-0.129(R2=0.705); the relationship between age and HR for horses 0-7 years old fit the equation Y=44.1X-0.179(R2=0.882). Seven-day-old horses had the highest HR values (106 ± 10.3 beat/min). The low frequency (LF) and high frequency (HF) powers increased with age in newborn to old horses. These changes in HR and HR variability appear to result from the effects of ageing. Three- to seven-year-old race horses had the lowest HR values (32.9 ± 3.5 beat/min) and the highest LF and HF powers except for the HF powers in the oldest horses. Race training may have contributed to these changes. Horses of ages greater than 25 years old had the highest HF powers and the lowest LF/HF ratios. In individual horses, 8 of the 15 horses over 25 years old had LF/HF ratios of less than 1.0; their HR variability appears to be unique, and they may have a different autonomic balance than horses of younger age

Milnacipran affects mouse impulsive, aggressive, and depressive-like behaviors in a distinct dose-dependent manner

Serotonin/noradrenaline reuptake inhibitors (SNRIs) are widely used for the treatment for major depressive disorder, but these drugs induce several side effects including increased aggression and impulsivity, which are risk factors for substance abuse, criminal involvement, and suicide. To address this issue, milnacipran (0, 3, 10, or 30 mg/kg), an SNRI and antidepressant, was intraperitoneally administered to mice prior to the 3-choice serial reaction time task, residente-intruder test, and forced swimming test to measure impulsive, aggressive, and depressive-like behaviors, respectively. A milnacipran dose of 10 mg/kg suppressed all behaviors, which was accompanied by increased dopamine and serotonin levels in the medial prefrontal cortex (mPFC) but not in the nucleus accumbens (NAc). Although the most effective dose for depressive-like behavior was 30 mg/kg, the highest dose increased aggressive behavior and unaffected impulsive behavior. Increased dopamine levels in the NAc could be responsible for the effects. In addition, the mice basal impulsivity was negatively correlated with the latency to the first agonistic behavior. Thus, the optimal dose range of milnacipran is narrower than previously thought. Finding drugs that increase serotonin and dopamine levels in the mPFC without affecting dopamine levels in the NAc is a potential strategy for developing novel antidepressants

Enhanced temperature variability in high-altitude climate change

In the present article, monthly mean temperature at 56 stations assembled in 18 regional groups in 10 major mountain ranges of the world were investigated. The periods of the analysis covered the last 50 to 110years. The author found that the variability of temperature in climatic time scale tends to increase with altitude in about 65% of the regional groups. A smaller number of groups, 20%, showed the fastest change at an intermediate altitude between the peaks (or ridges) and their foot, while the remaining small number of sites, 15%, showed the largest trends at the foot of mountains. This tendency provides a useful base for considering and planning the climate impact evaluations. The reason for the amplification of temperature variation at high altitudes is traced back to the increasing diabatic processes in the mid- and high troposphere as a result of the cloud condensation. This situation results from the fact that the radiation balance at the earth's surface is transformed more efficiently into latent heat of evaporation rather than sensible heat, the ratio between them being 4 to 1. Variation in the surface evaporation is converted into heat upon condensation into cloud particles and ice crystals in the mid- and high troposphere. Therefore, this is the altitude where the result of the surface radiation change is effectively transferred. Further, the low temperature of the environment amplifies the effect of the energy balance variation on the surface temperature, as a result of the functional shape of Stefan-Boltzmann law. These processes altogether contribute to enhancing temperature variability at high altitudes. The altitude plays an important role in determining the temperature variability, besides other important factors such as topography, surface characteristics, cryosphere/temperature feedback and the frequency and intensity of an inversion. These processes have a profound effect not only on the ecosystem but also on glaciers and permafros

Effects of Elastic Modulus on Single Fiber Uniaxial Deformation

Undergraduate Research ScholarshipTissue engineering offers reductions in both mortality and morbidity of tissue recipients as well as the possibility of a vast pool of implantable tissues. Regrettably, use of engineered tissue is limited by mechanical properties that are insufficient compared to native tissues. A promising avenue to improve this deficiency is mechanical stimulation. Mechanical stimulation, such as the introduction of a cyclical load during tissue formation, is a multi-step process beginning with the translation of scaffold material properties into scaffold micro-deformation. The present study explored this relationship by characterizing the effect of scaffold elastic modulus and initial fiber geometry on scaffold micro-deformation. Finite element modeling was utilized to simulate three geometrically identical sets of 100 unique fiber shapes, with differing elastic moduli of 10 MPa, 100 MPa, and 1000 MPa. Fibers were then strained to 20% strain via ABAQUS, finite element software. Normalized force curves during the straining process, as well as fiber geometry characterized via sine Fourier series and tortuosity, were calculated for each fiber set at 0 and 20% strain. Single fiber deformation appeared to be independent of fiber modulus. This study also indicated that amplitudes of fiber Fourier coefficients reduce proportionally during uniaxial extension, revealing a 75±7% reduction in wavelength amplitude from 0 to 20% strain in all fiber sets. By further defining the role of scaffold mechanics in mechanical stimulation, it is projected that this research will provide a platform for rapid optimization of external environment for tissue growth.This study was funded in part by an instrumentation and facilities grant from the Institute for Materials Research (IMR) at The Ohio State University.Undergraduate Research ScholarshipNo embarg

Japanese scientific activities in the Arctic in retrospect and prospect

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

Observed Mass Balance of Mountain Glaciers and Greenland Ice Sheet in the 20th Century and the Present Trends

Glacier mass balance and secular changes in mountain glaciers and ice caps are evaluated from the annual net balance of 137 glaciers from 17 glacierized regions of the world. Further, the winter and summer balances for 35 glaciers in 11 glacierized regions are analyzed. The global means are calculated by weighting glacier and regional surface areas. The area-weighted global mean net balance for the period 1960-2000 is −270±34mma−1w.e. (water equivalent, in mm per year) or (−149±19km3a−1w.e.), with a winter balance of 890±24mma−1w.e. (490±13km3a−1w.e.) and a summer balance of −1,175±24mma−1w.e. (−647±13km3a−1w.e.). The linear-fitted global net balance is accelerating at a rate of −9±2.1 mm a−2. The main driving force behind this change is the summer balance with an acceleration of −10±2.0mm a−2. The decadal balance, however, shows significant fluctuations: summer melt reached its peak around 1945, followed by a decrease. The negative trend in the annual net balance is interrupted by a period of stagnation from 1960s to 1980s. Some regions experienced a period of positive net balance during this time, for example, Europe. The balance has become strongly negative since the early 1990s. These decadal fluctuations correspond to periods of global dimming (for smaller melt) and global brightening (for larger melt). The total radiation at the surface changed as a result of an imbalance between steadily increasing greenhouse gases and fluctuating aerosol emissions. The mass balance of the Greenland ice sheet and the surrounding small glaciers, averaged for the period of 1950-2000, is negative at −74±10 mma−1w.e. (−128±18km3a−1w.e.) with an accumulation of 297±33mma−1w.e. (519±58km3a−1w.e.), melt ablation −169±18mma−1w.e. (−296±31km3a−1w.e.), calving ablation −181±19mma−1w.e. (−316±33km3a−1w.e.) and the bottom melt-21±2mma−1w.e. (−35±4km3a−1w.e.). Almost half (−60±3km3a−1) of the net mass loss comes from mountain glaciers and ice caps around the ice sheet. At present, it is difficult to detect any statistically significant trends for these components. The total mass balance of the Antarctic ice sheet is considered to be too premature to evaluate. The estimated sea-level contributions in the twentieth Century are 5.7±0.5cm by mountain glaciers and ice caps outside Antarctica, 1.9±0.5cm by the Greenland ice sheet, and 2cm by ocean thermal expansion. The difference of 7cm between these components and the estimated value with tide-gage networks (17cm) must result from other sources such as the mass balance of glaciers of Antarctica, especially small glaciers separated from the ice shee

Observed Long-Term Variations of Solar Irradiance at the Earth's Surface

The variation of global radiation (sum of direct solar and diffuse sky radiation) at the Earth's surface is examined based on pyranometer measurements at about 400~sites. The period of the study covers in general the last 50 years. For Europe the study is extended to the beginning of observations in the 1920s and 1930s. Global radiation generally increased in Europe from the 1920s to the 1950s. After the late 1950s and early 1960s global radiation began to decrease in most areas of the world at a mean rate of 0.7 Wm−2a−1 until 1980s, thereafter 75%; of the stations showed a recovery at a mean rate of 0.7 Wm−2a−1. All stations in the Polar region, which are far from aerosol sources, also show this pattern of change. At the remaining 25% of the stations the decrease has continued to present. These regions are a part of China, most of India, and Central Africa. Both during the declining and recovering phases global radiation observed under the cloudless condition also followed the same tendency, indicating the simultaneous and parallel changes of aerosol and cloud conditions. Long-term observations of total zenith transmittance of the atmosphere indicate a decrease in transmittance to the mid 1980s and an increase after this period. Since the brighter and darker periods correspond to relatively warmer and colder periods, the present study offers the possibility to quantitatively evaluate the mutual relationships between the solar irradiance, atmospheric transmittance, cloud conditions and air temperatur