19,858 research outputs found
A pilot search for mm-wavelength recombination lines from emerging ionized winds in pre-planetary nebulae candidates
We report the results from a pilot search for radio recombination line (RRL)
emission at millimeter wavelengths in a small sample of pre-planetary nebulae
(pPNe) and young PNe (yPNe) with emerging central ionized regions. Observations
of the H30\alpha, H31a, H39a, H41a, H48b, H49b, H51b, and H55g lines at 1 and
3mm have been performed with the IRAM 30 m radio telescope. These lines are
excellent probes of the dense inner (<~150 au) and heavily obscured regions of
these objects, where the yet unknown agents for PN-shaping originate. We
detected mm-RRLs in three objects: CRL 618, MWC 922, and M 2-9. For CRL 618,
the only pPN with previous published detections of H41a, H35a, and H30a
emission, we find significant changes in the line profiles indicating that
current observations are probing regions of the ionized wind with larger
expansion velocities and mass-loss rate than ~29 years ago. In the case of MWC
922, we observe a drastic transition from single-peaked profiles at 3mm to
double-peaked profiles at 1mm, which is consistent with maser amplification of
the highest frequency lines; the observed line profiles are compatible with
rotation and expansion of the ionized gas, probably arranged in a disk+wind
system around a ~5-10 Msun central mass. In M 2-9, the mm-RRL emission appears
to be tracing a recent mass outburst by one of the stars of the central binary
system. We present the results from non-LTE line and continuum radiative
transfer models, which enables us to constrain the structure, kinematics, and
physical conditions (electron temperature and density) of the ionized cores of
our sample. (abridged). We deduce mass-loss rates of ~1e-6-1e-7 Msun/yr, which
are significantly higher than the values adopted by stellar evolution models
currently in use and would result in a transition from the asymptotic giant
branch to the PN phase faster than hitherto assumed.Comment: Accepted by Astronomy and Astrophysics. 28 pages, including figure
Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius association
We present the discovery of a companion near the deuterium burning mass limit
located at a very wide distance, at an angular separation of 4.6+/-0.1 arcsec
(projected distance of ~ 670 AU) from UScoCTIO108, a brown dwarf of the very
young Upper Scorpius association. Optical and near-infrared photometry and
spectroscopy confirm the cool nature of both objects, with spectral types of M7
and M9.5, respectively, and that they are bona fide members of the association,
showing low gravity and features of youth. Their masses, estimated from the
comparison of their bolometric luminosities and theoretical models for the age
range of the association, are 60+/-20 and 14^{+2}_{-8} MJup, respectively. The
existence of this object around a brown dwarf at this wide orbit suggests that
the companion is unlikely to have formed in a disk based on current planet
formation models. Because this system is rather weakly bound, they did not
probably form through dynamical ejection of stellar embryos.Comment: 10 pages, including 4 figures and 2 table
An improved model of the Earth's gravitational field: GEM-T1
Goddard Earth Model T1 (GEM-T1), which was developed from an analysis of direct satellite tracking observations, is the first in a new series of such models. GEM-T1 is complete to degree and order 36. It was developed using consistent reference parameters and extensive earth and ocean tidal models. It was simultaneously solved for gravitational and tidal terms, earth orientation parameters, and the orbital parameters of 580 individual satellite arcs. The solution used only satellite tracking data acquired on 17 different satellites and is predominantly based upon the precise laser data taken by third generation systems. In all, 800,000 observations were used. A major improvement in field accuracy was obtained. For marine geodetic applications, long wavelength geoidal modeling is twice as good as in earlier satellite-only GEM models. Orbit determination accuracy has also been substantially advanced over a wide range of satellites that have been tested
Human Amniocytes Are Receptive to Chemically Induced Reprogramming to Pluripotency
Restoring pluripotency using chemical compounds alone would be a major step forward in developing clinical-grade pluripotent stem cells, but this has not yet been reported in human cells. We previously demonstrated that VPA_ AFS cells, human amniocytes cultivated with valproic acid (VPA) acquired functional pluripotency while remaining distinct from human embryonic stem cells (hESCs), questioning the relationship between the modulation of cell fate and molecular regulation of the pluripotency network. Here, we used single-cell analysis and functional assays to reveal that VPA treatment resulted in a homogeneous population of self-renewing non-transformed cells that fulfill the hallmarks of pluripotency, i.e., a short G1 phase, a dependence on glycolytic metabolism, expression of epigenetic modifications on histones 3 and 4, and reactivation of endogenous OCT4 and downstream targets at a lower level than that observed in hESCs. Mechanistic insights into the process of VPA-induced reprogramming revealed that it was dependent on OCT4 promoter activation, which was achieved independently of the PI3K (phosphatidylinositol 3-kinase)/ AKT/ mTOR (mammalian target of rapamycin) pathway or GSK3 beta inhibition but was concomitant with the presence of acetylated histones H3K9 and H3K56, which promote pluripotency. Our data identify, for the first time, the pluripotent transcriptional and molecular signature and metabolic status of human chemically induced pluripotent stem cells
Movement Analysis of Philippine Folk Dance Tinikling
The purpose of the study was to describe the dance movements of the folk dance Tinikling which is the most popular traditional dance and former national dance of the Philippines. The researchers adopted the movement analysis method similar to that of Mackenzie that involves the (1) description of the actual movements which occur at the joints involved; (2) the plane in which the movement occurs; and (3) the muscles producing the movement (agonist & antagonist). In addition, the researchers also had done a mechanical analysis on the lever type involved in the execution of the dance movement in terms of force, axis, and resistance. The prominent dance steps in the Philippine local dance Tinikling are the (1) running, (2) tinikling steps, (3) diagonal step, and (4) straddle jump with a turn step. The joints involved are: hip muscle which is ball and socket type of joint; and knee and ankle which are hinge joints. The major muscles involved in the dance include mostly the lower body muscle groups such as the quadriceps, hamstring, gluts, adductor muscle group, and calves. The type of lever used in performing the dance comprise majority of 1st, 2nd and 3rd class levers. Thus, the Tinikling is a viable dance which could improve the health related fitness of the performers in terms of muscular strength, muscular endurance, cardiovascular endurance and flexibility. Also, the dance could improve skill-related fitness such as power, agility, balance and coordination
Characterization of optical properties of ZnO nanoparticles for quantitative imaging of transdermal transport
Widespread applications of ZnO nanoparticles (NP) in sun-blocking cosmetic products have raised safety concerns related to their potential transdermal penetration and resultant cytotoxicity. Nonlinear optical microscopy provides means for high-contrast imaging of ZnO NPs lending in vitro and in vivo assessment of the nanoparticle uptake in skin, provided their nonlinear optical properties are characterized. We report on this characterization using ZnO NP commercial product, Zinclear, mean-sized 21 nm. Two-photon action cross-section of this bandgap material (Ebg = 3.37 eV, λbg = 370 nm) measured by two techniques yielded consistent results of ηZnOÏZnO(2ph) = 6.2 ± 0.8 ÎŒGM at 795 nm, and 32 ± 6 ÎŒGM at 770 nm per unit ZnO crystal cell, with the quantum efficiency of ηZnO = (0.9 ± 0.2) %. In order to demonstrate the quantitative imaging, nonlinear optical microscopy images of the excised human skin topically treated with Zinclear were acquired and processed using ÏZnO(2ph) and ηZnOvalues yielding nanoparticle concentration map in skin. Accumulations of Zinclear ZnO nanoparticles were detected only on the skin surface and in skin folds reaching concentrations of 800 NPs per ÎŒm3
Nanoinformatics: developing new computing applications for nanomedicine
Nanoinformatics has recently emerged to address the need of computing applications at the nano level. In this regard, the authors have participated in various initiatives to identify its concepts, foundations and challenges. While nanomaterials open up the possibility for developing new devices in many industrial and scientific areas, they also offer breakthrough perspectives for the prevention, diagnosis and treatment of diseases. In this paper, we analyze the different aspects of nanoinformatics and suggest five research topics to help catalyze new research and development in the area, particularly focused on nanomedicine. We also encompass the use of informatics to further the biological and clinical applications of basic research in nanoscience and nanotechnology, and the related concept of an extended ?nanotype? to coalesce information related to nanoparticles. We suggest how nanoinformatics could accelerate developments in nanomedicine, similarly to what happened with the Human Genome and other -omics projects, on issues like exchanging modeling and simulation methods and tools, linking toxicity information to clinical and personal databases or developing new approaches for scientific ontologies, among many others
Large Deformation Effects in the N = Z 44Ti Compound Nucleus
The N = Z 44Ti* nucleus has been populated in Fusion Evaporation process at
very high excitation energies and angular momenta using two entrance channels
with different mass-asymmetry. The deformation effects in the rapidly rotating
nuclei have been investigated through the energy distribution of the
alpha-particle combined to statistical-model calculations. In the case of
low-multiplicity events, the ratio between first particle emitted has been
measured and shows significant disagreement with the predictions of the
statistical-model. This may explain The large discrepancies observed in proton
energy spectra measured in previous experiments performed in the same mass
region.Comment: Proceeding of the 10th International Conference on Nuclear Reaction
Mechanisms, Varenna Italy, June 9-13 2003. 10 pages, 6 figures, 1 tabl
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