5,720 research outputs found
Cancelled - Berkeley\u27s A Priori Argument for God\u27s Exstence
Berkeleyâs appeal to a posteriori arguments for Godâs existence supports belief only in a God who is finite. But by appealing to an a priori argument for Godâs existence, Berkeley emphasizes Godâs infinity. In this latter argument, God is not the efficient cause of particular finite things in the world, for such an explanation does not provide a justification or rationale for why the totality of finite things would exist in the first place. Instead, God is understood as the creator of the total unity of all there is, the whole of creation. In this a priori argument, we should not focus on the specific objects that God creates, for that requires that we think that God knows each finite thing as distinct from every other. Rather, we should recognize how God creates all things in creating the complex, infinite totality of finite perceivings, each of which exists in virtue of the distinctions and relations it expresses
Unique thermal behavior of sphingomyelin species with nonhydroxy and 2-hydroxy very-long-chain (C28-C32) PUFAs
In rat germ cells and spermatozoa, sphingomyelin (SM) contains molecular species with nonhydroxy (n) and 2-hydroxy (h) very-long-chain polyunsaturated fatty acids (V), the most abundant being SMs with (n- and h-) 28:4n-6, 30:5n-6, and 32:5n-6 as acyl chains. The aim of this study was to gain information about their thermotropic behavior and interactions with other lipids. After isolation from rat testis, multilamellar and giant unilamellar vesicles from these SMs were examined using fluorescent probes. Only n-32:5 SM and h-32:5 SM displayed a gel-liquid transition temperature (Tt â 21?22°C), the rest remaining in the liquid state in the 5°C?45°C range. The degree of order was larger in bilayers of any of the h-V SMs than in those of their chain-matched n-V SMs. Both, but n-V SM relatively more than h-V SM, decreased the Tt of dimyristoylphosphatidylcholine as their proportion increased in binary phosphatidylcholine:SM liposomes. In contrast to the established ability of 16:0 SM to form lateral cholesterol/SM-rich ordered domains in ternary dioleoylphosphatidylcholine:cholesterol:SM bilayers, neither n-V SM nor h-V SM showed a tendency to do so. Thus, these SMs are in the fluid state and are not involved in this type of domains in spermatozoa at physiological temperatures. However, this state could be altered at the very low temperatures at which these gametes are usually preserved.Fil: Peñalva, Daniel Alejandro. Consejo Nacional de Investigaciones Cientificas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Bahia Blanca. Instituto de Investigaciones BioquĂmicas Bahia Blanca (i); ArgentinaFil: Furland, Natalia Edith. Consejo Nacional de Investigaciones Cientificas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Bahia Blanca. Instituto de Investigaciones BioquĂmicas Bahia Blanca (i); ArgentinaFil: Lopez, Gustavo H.. Universidad Nacional del Sur. Departamento de BiologĂa, BioquĂmica y Farmacia; ArgentinaFil: Aveldaño, Marta Isabel. Consejo Nacional de Investigaciones Cientificas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Bahia Blanca. Instituto de Investigaciones BioquĂmicas Bahia Blanca (i); ArgentinaFil: Antollini, Silvia Susana. Consejo Nacional de Investigaciones Cientificas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Bahia Blanca. Instituto de Investigaciones BioquĂmicas Bahia Blanca (i); Argentin
Seeing double with K2: Testing re-inflation with two remarkably similar planets around red giant branch stars
Despite more than 20 years since the discovery of the first gas giant planet
with an anomalously large radius, the mechanism for planet inflation remains
unknown. Here, we report the discovery of EPIC228754001.01, an inflated gas
giant planet found with the NASA K2 Mission, and a revised mass for another
inflated planet, K2-97b. These planets reside on ~9 day orbits around host
stars which recently evolved into red giants. We constrain the irradiation
history of these planets using models constrained by asteroseismology and
Keck/HIRES spectroscopy and radial velocity measurements. We measure planet
radii of 1.31 +\- 0.11 Rjup and and 1.30 +\- 0.07 Rjup, respectively. These
radii are typical for planets receiving the current irradiation, but not the
former, zero age main sequence irradiation of these planets. This suggests that
the current sizes of these planets are directly correlated to their current
irradiation. Our precise constraints of the masses and radii of the stars and
planets in these systems allow us to constrain the planetary heating efficiency
of both systems as 0.03% +0.03%/-0.02%. These results are consistent with a
planet re-inflation scenario, but suggest the efficiency of planet re-inflation
may be lower than previously theorized. Finally, we discuss the agreement
within 10% of stellar masses and radii, and planet masses, radii, and orbital
periods of both systems and speculate that this may be due to selection bias in
searching for planets around evolved stars.Comment: 18 pages, 15 figures, accepted to AJ. Figures 11, 12, and 13 are the
key figures of the pape
Theory of the Quantum Hall Smectic Phase II: Microscopic Theory
We present a microscopic derivation of the hydrodynamic theory of the Quantum
Hall smectic or stripe phase of a two-dimensional electron gas in a large
magnetic field. The effective action of the low energy is derived here from a
microscopic picture by integrating out high energy excitations with a scale of
the order the cyclotron energy.The remaining low-energy theory can be expressed
in terms of two canonically conjugate sets of degrees of freedom: the
displacement field, that describes the fluctuations of the shapes of the
stripes, and the local charge fluctuations on each stripe.Comment: 20 pages, RevTex, 3 figures, second part of cond-mat/0105448 New and
improved Introduction. Final version as it will appear in Physical Review
Downregulation of 26S proteasome catalytic activity promotes epithelial-mesenchymal transition.
The epithelial-mesenchymal transition (EMT) endows carcinoma cells with phenotypic plasticity that can facilitate the formation of cancer stem cells (CSCs) and contribute to the metastatic cascade. While there is substantial support for the role of EMT in driving cancer cell dissemination, less is known about the intracellular molecular mechanisms that govern formation of CSCs via EMT. Here we show that ÎČ2 and ÎČ5 proteasome subunit activity is downregulated during EMT in immortalized human mammary epithelial cells. Moreover, selective proteasome inhibition enabled mammary epithelial cells to acquire certain morphologic and functional characteristics reminiscent of cancer stem cells, including CD44 expression, self-renewal, and tumor formation. Transcriptomic analyses suggested that proteasome-inhibited cells share gene expression signatures with cells that have undergone EMT, in part, through modulation of the TGF-ÎČ signaling pathway. These findings suggest that selective downregulation of proteasome activity in mammary epithelial cells can initiate the EMT program and acquisition of a cancer stem cell-like phenotype. As proteasome inhibitors become increasingly used in cancer treatment, our findings highlight a potential risk of these therapeutic strategies and suggest a possible mechanism by which carcinoma cells may escape from proteasome inhibitor-based therapy
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Electrophysiological Guidance of Epidural Electrode Array Implantation over the Human Lumbosacral Spinal Cord to Enable Motor Function after Chronic Paralysis.
Epidural electrical stimulation (EES) of the spinal cord has been shown to restore function after spinal cord injury (SCI). Characterization of EES-evoked motor responses has provided a basic understanding of spinal sensorimotor network activity related to EES-enabled motor activity of the lower extremities. However, the use of EES-evoked motor responses to guide EES system implantation over the spinal cord and their relation to post-operative EES-enabled function in humans with chronic paralysis attributed to SCI has yet to be described. Herein, we describe the surgical and intraoperative electrophysiological approach used, followed by initial EES-enabled results observed in 2 human subjects with motor complete paralysis who were enrolled in a clinical trial investigating the use of EES to enable motor functions after SCI. The 16-contact electrode array was initially positioned under fluoroscopic guidance. Then, EES-evoked motor responses were recorded from select leg muscles and displayed in real time to determine electrode array proximity to spinal cord regions associated with motor activity of the lower extremities. Acceptable array positioning was determined based on achievement of selective proximal or distal leg muscle activity, as well as bilateral muscle activation. Motor response latencies were not significantly different between intraoperative recordings and post-operative recordings, indicating that array positioning remained stable. Additionally, EES enabled intentional control of step-like activity in both subjects within the first 5 days of testing. These results suggest that the use of EES-evoked motor responses may guide intraoperative positioning of epidural electrodes to target spinal cord circuitry to enable motor functions after SCI
Formation of Super-Earths
Super-Earths are the most abundant planets known to date and are
characterized by having sizes between that of Earth and Neptune, typical
orbital periods of less than 100 days and gaseous envelopes that are often
massive enough to significantly contribute to the planet's overall radius.
Furthermore, super-Earths regularly appear in tightly-packed multiple-planet
systems, but resonant configurations in such systems are rare. This chapters
summarizes current super-Earth formation theories. It starts from the formation
of rocky cores and subsequent accretion of gaseous envelopes. We follow the
thermal evolution of newly formed super-Earths and discuss their atmospheric
mass loss due to disk dispersal, photoevaporation, core-cooling and collisions.
We conclude with a comparison of observations and theoretical predictions,
highlighting that even super-Earths that appear as barren rocky cores today
likely formed with primordial hydrogen and helium envelopes and discuss some
paths forward for the future.Comment: Invited review accepted for publication in the 'Handbook of
Exoplanets,' Planet Formation section, Springer Reference Works, Juan Antonio
Belmonte and Hans Deeg, Ed
On the Electromagnetic Response of Charged Bosons Coupled to a Chern-Simons Gauge Field: A Path Integral Approach
We analyze the electromagnetic response of a system of charged bosons coupled
to a Chern-Simons gauge field. Path integral techniques are used to obtain an
effective action for the particle density of the system dressed with quantum
fluctuations of the CS gauge field. From the action thus obtained we compute
the U(1) current of the theory for an arbitrary electromagnetic external field.
For the particular case of a homogeneous external magnetic field, we show that
the quantization of the transverse conductivity is exact, even in the presence
of an arbitrary impurity distribution. The relevance of edge states in this
context is analyzed. The propagator of density fluctuations is computed, and an
effective action for the matter density in the presence of a vortex excitation
is suggested.Comment: LaTex file, 27 pages, no figure
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