University of Turku

About: University of Turku is a education organization based out in Turku, Finland. It is known for research contribution in the topics: Population & Galaxy. The organization has 16296 authors who have published 45124 publications receiving 1505428 citations. The organization is also known as: Turun yliopisto & Åbo universitet.

Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

Abstract: A precision measurement by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49 × 105 antiproton events and 2.42 × 109 proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ∼60 to ∼500 GV, the antiproton ¯p, proton p, and positron eþ fluxes are found to have nearly identical rigidity dependence and the electron e− flux exhibits a different rigidity dependence. Below 60 GV, the ( ¯ p=p), ( ¯ p=eþ), and (p=eþ) flux ratios each reaches a maximum. From ∼60 to ∼500 GV, the ( ¯ p=p), ( ¯ p=eþ), and (p=eþ) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.

Mice devoid of γ-aminobutyrate type A receptor β3 subunit have epilepsy, cleft palate, and hypersensitive behavior

Abstract: γ-Aminobutyric acid type A receptors (GABAA-Rs) mediate the bulk of rapid inhibitory synaptic transmission in the central nervous system. The β3 subunit is an essential component of the GABAA-R in many brain regions, especially during development, and is implicated in several pathophysiologic processes. We examined mice harboring a β3 gene inactivated by gene targeting. GABAA-R density is approximately halved in brain of β3-deficient mice, and GABAA-R function is severely impaired. Most β3-deficient mice die as neonates; some neonatal mortality, but not all, is accompanied by cleft palate. β3-deficient mice that survive are runted until weaning but achieve normal body size by adulthood, although with reduced life span. These mice are fertile but mothers fail to nurture offspring. Brain morphology is grossly normal, but a number of behaviors are abnormal, consistent with the widespread location of the β3 subunit. The mice are very hyperactive and hyperresponsive to human contact and other sensory stimuli, and often run continuously in tight circles. When held by the tail, they hold all paws in like a ball, which is frequently a sign of neurological impairment. They have difficulty swimming, walking on grids, and fall off platforms and rotarods, although they do not have a jerky gait. β3-deficient mice display frequent myoclonus and occasional epileptic seizures, documented by electroencephalographic recording. Hyperactivity, lack of coordination, and seizures are consistent with reduced presynaptic inhibition in spinal cord and impaired inhibition in higher cortical centers and/or pleiotropic developmental defects.

Electron and Positron Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

Abstract: Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at ∼30 GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the differing behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons.

Acute doxorubicin cardiotoxicity involves cardiomyocyte apoptosis.

Abstract: Despite well-documented cardiotoxic effects, doxorubicin remains a major anticancer agent. To study the role of myocardial apoptosis following doxorubicin administration, male Wistar rats were exposed to 1.25, 2.5, and 5 mg/kg of i.p. doxorubicin and terminated on days 1-7 in groups of five. Doxorubicin caused a significant (P < 0.001) and dose-dependent induction of cardiomyocyte apoptosis at 24-48 h after the injection. Repeated injections of 2.5 mg/kg given every other day resulted in peaks of apoptosis at 24 h after each injection. However, no additive effect of repeated dosing was noted. In histological samples, alterations in the cytoskeletal apparatus with focal loss of contractile elements were seen after a single injection. Myocyte necrosis was absent. Thus, acute doxorubicin-induced cardiotoxicity involves cardiomyocyte apoptosis, a potentially preventable form of myocardial tissue loss.