267 research outputs found
Short-term occupations at high elevation during the Middle Paleolithic at Kalavan 2 (Republic of Armenia)
The Armenian highlands encompasses rugged and environmentally diverse landscapes and is characterized by a mosaic of distinct ecological niches and large temperature gradients. Strong seasonal fluctuations in resource availability along topographic gradients likely prompted Pleistocene hominin groups to adapt by adjusting their mobility strategies. However, the role that elevated landscapes played in hunter-gatherer settlement systems during the Late Pleistocene (Middle Palaeolithic [MP]) remains poorly understood. At 1640 m above sea level, the MP site of Kalavan 2 (Armenia) is ideally positioned for testing hypotheses involving elevation-dependent seasonal mobility and subsistence strategies. Renewed excavations at Kalavan 2 exposed three main occupation horizons and ten additional low densities lithic and faunal assemblages. The results provide a new chronological, stratigraphical, and paleoenvironmental framework for hominin behaviors between ca. 60 to 45 ka. The evidence presented suggests that the stratified occupations at Kalavan 2 locale were repeated ephemerally most likely related to hunting in a high-elevation within the mountainous steppe landscape
The Orbital Structure of Triaxial Galaxies with Figure Rotation
We survey the properties of all orbit families in the rotating frame of a
family of realistic triaxial potentials with central supermassive black holes
(SMBHs). In such galaxies, most regular box orbits (vital for maintaining
triaxiality) are associated with resonances which occupy two-dimensional
surfaces in configuration space. For slow figure rotation all orbit families
are largely stable. At intermediate pattern speeds a significant fraction of
the resonant box orbits as well as inner long-axis tubes are destabilized by
the "envelope doubling" that arises from the Coriolis forces and are driven
into the destabilizing center. Thus, for pattern rotation periods .2 Gyr < Tp <
5 Gyr, the two orbit families that are most important for maintaining
triaxiality are highly chaotic. As pattern speed increases there is also a
sharp decrease in the overall fraction of prograde short-axis tubes and a
corresponding increase in the retrograde variety. At the highest pattern speeds
(close to that of triaxial bars), box-like orbits undergo a sudden transition
to a new family of stable retrograde loop-like orbits, which resemble orbits in
three-dimensional bars, and circulate about the short axis. Our analysis
implies that triaxial systems (with central cusps and SMBHs) can either have
high pattern speeds like fast bars or low patten speeds like triaxial
elliptical galaxies or dark matter halos found in N-body simulations.
Intermediate pattern speeds produce a high level of stochasticity in both the
box and inner long-axis tube orbit families implying that stable triaxial
systems are unlikely to have such pattern speeds.Comment: Version accepted for publication in ApJ, Vol 727, Feb. 1 issue, 201
A Search for the Most Massive Galaxies. II. Structure, Environment and Formation
We study a sample of 43 early-type galaxies, selected from the SDSS because
they appeared to have velocity dispersion > 350 km/s. High-resolution
photometry in the SDSS i passband using HRC-ACS on board the HST shows that
just less than half of the sample is made up of superpositions of two or three
galaxies, so the reported velocity dispersion is incorrect. The other half of
the sample is made up of single objects with genuinely large velocity
dispersions. None of these objects has sigma larger than 426 +- 30 km/s. These
objects define rather different relations than the bulk of the early-type
galaxy population: for their luminosities, they are the smallest, most massive
and densest galaxies in the Universe. Although the slopes of the scaling
relations they define are rather different from those of the bulk of the
population, they lie approximately parallel to those of the bulk "at fixed
sigma". These objects appear to be of two distinct types: the less luminous
(M_r>-23) objects are rather flattened and extremely dense for their
luminosities -- their properties suggest some amount of rotational support and
merger histories with abnormally large amounts of gaseous dissipation. The more
luminous objects (M_r<-23) tend to be round and to lie in or at the centers of
clusters. Their properties are consistent with the hypothesis that they are
BCGs. Models in which BCGs form from predominantly radial mergers having little
angular momentum predict that they should be prolate. If viewed along the major
axis, such objects would appear to have abnormally large sigma for their sizes,
and to be abnormally round for their luminosities. This is true of the objects
in our sample once we account for the fact that the most luminous galaxies
(M_r<-23.5), and BCGs, become slightly less round with increasing luminosity.Comment: 21 pages, 19 figures, accepted for publication in MNRA
Vitamin B12 Attenuates Changes in Phospholipid Levels Related to Oxidative Stress in SH-SY5Y Cells
Oxidative stress is closely linked to Alzheimer’s disease (AD), and is detected peripherally
as well as in AD-vulnerable brain regions. Oxidative stress results from an imbalance between
the generation and degradation of reactive oxidative species (ROS), leading to the oxidation of
proteins, nucleic acids, and lipids. Extensive lipid changes have been found in post mortem AD
brain tissue; these changes include the levels of total phospholipids, sphingomyelin, and ceramide,
as well as plasmalogens, which are highly susceptible to oxidation because of their vinyl ether
bond at the sn-1 position of the glycerol-backbone. Several lines of evidence indicate that a deficiency in the neurotropic vitamin B12 is linked with AD. In the present study, treatment of the
neuroblastoma cell line SH-SY5Y with vitamin B12 resulted in elevated levels of phosphatidylcholine,
phosphatidylethanolamine, sphingomyelin, and plasmalogens. Vitamin B12 also protected plasmalogens from hydrogen peroxide (H2O2
)-induced oxidative stress due to an elevated expression of the
ROS-degrading enzymes superoxide-dismutase (SOD) and catalase (CAT). Furthermore, vitamin B12
elevates plasmalogen synthesis by increasing the expression of alkylglycerone phosphate synthase
(AGPS) and choline phosphotransferase 1 (CHPT1) in SH-SY5Y cells exposed to H2O2
-induced
oxidative stress
Aspartame and Its Metabolites Cause Oxidative Stress and Mitochondrial and Lipid Alterations in SH-SY5Y Cells
Due to a worldwide increase in obesity and metabolic disorders such as type 2 diabetes,
synthetic sweeteners such as aspartame are frequently used to substitute sugar in the diet. Possible
uncertainties regarding aspartame’s ability to induce oxidative stress, amongst others, has led to the
recommendation of a daily maximum dose of 40 to 50 mg per kg. To date, little is known about the
effects of this non-nutritive sweetener on cellular lipid homeostasis, which, besides elevated oxidative
stress, plays an important role in the pathogenesis of various diseases, including neurodegenerative
diseases such as Alzheimer’s disease. In the present study, treatment of the human neuroblastoma
cell line SH-SY5Y with aspartame (271.7 µM) or its three metabolites (aspartic acid, phenylalanine,
and methanol (271.7 µM)), generated after digestion of aspartame in the human intestinal tract,
resulted in significantly elevated oxidative stress associated with mitochondrial damage, which was
illustrated with reduced cardiolipin levels, increased gene expression of SOD1/2, PINK1, and FIS1,
and an increase in APF fluorescence. In addition, treatment of SH-SY5Y cells with aspartame or
aspartame metabolites led to a significant increase in triacylglycerides and phospholipids, especially
phosphatidylcholines and phosphatidylethanolamines, accompanied by an accumulation of lipid
droplets inside neuronal cells. Due to these lipid-mediating properties, the use of aspartame as a
sugar substitute should be reconsidered and the effects of aspartame on the brain metabolism should
be addressed in vivo
Short-term occupations at high elevation during the Middle Paleolithic at Kalavan 2 (Republic of Armenia)
The Armenian highlands encompasses rugged and environmentally diverse landscapes and is characterized by a mosaic of distinct ecological niches and large temperature gradients. Strong seasonal fluctuations in resource availability along topographic gradients likely prompted Pleistocene hominin groups to adapt by adjusting their mobility strategies. However, the role that elevated landscapes played in hunter-gatherer settlement systems during the Late Pleistocene (Middle Palaeolithic [MP]) remains poorly understood. At 1640 m above sea level, the MP site of Kalavan 2 (Armenia) is ideally positioned for testing hypotheses involving elevation-dependent seasonal mobility and subsistence strategies. Renewed excavations at Kalavan 2 exposed three main occupation horizons and ten additional low densities lithic and faunal assemblages. The results provide a new chronological, stratigraphical, and paleoenvironmental framework for hominin behaviors between ca. 60 to 45 ka. The evidence presented suggests that the stratified occupations at Kalavan 2 locale were repeated ephemerally most likely related to hunting in a high-elevation within the mountainous steppe landscape.info:eu-repo/semantics/publishedVersio
Therapeutic Effects of Topical Application of Ozone on Acute Cutaneous Wound Healing
This study was undertaken to evaluate the therapeutic effects of topical ozonated olive oil on acute cutaneous wound healing in a guinea pig model and also to elucidate its therapeutic mechanism. After creating full-thickness skin wounds on the backs of guinea pigs by using a 6 mm punch biopsy, we examined the wound healing effect of topically applied ozonated olive oil (ozone group), as compared to the pure olive oil (oil group) and non-treatment (control group). The ozone group of guinea pig had a significantly smaller wound size and a residual wound area than the oil group, on days 5 (P<0.05) and 7 (P<0.01 and P<0.05) after wound surgery, respectively. Both hematoxylin-eosin staining and Masson-trichrome staining revealed an increased intensity of collagen fibers and a greater number of fibroblasts in the ozone group than that in the oil group on day 7. Immunohistochemical staining demonstrated upregulation of platelet derived growth factor (PDGF), transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) expressions, but not fibroblast growth factor expression in the ozone group on day 7, as compared with the oil group. In conclusion, these results demonstrate that topical application of ozonated olive oil can accelerate acute cutaneous wound repair in a guinea pig in association with the increased expression of PDGF, TGF-β, and VEGF
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