98 research outputs found
Content of lipids in blood and tissues of animals during hypodynamia
Experiments on 97 rats and 50 rabbits were undertaken to study the influence of hypodynamia on the lipid content in the blood, liver, heart, and in the aorta. Reduction of muscular activity contributed to the increase of cholesterol and beta lipoprotein levels in the blood and to accumulation of cholesterol in the liver and the heart. The total lipid content in these tissues decreased. In the aorta the total lipid content increased, while lecithin and cephalin figures went down. The character of biochemical changes in hypodynamia resembles in many ways the lipid metabolism changes in atherosclerosis
A variational problem on Stiefel manifolds
In their paper on discrete analogues of some classical systems such as the
rigid body and the geodesic flow on an ellipsoid, Moser and Veselov introduced
their analysis in the general context of flows on Stiefel manifolds. We
consider here a general class of continuous time, quadratic cost, optimal
control problems on Stiefel manifolds, which in the extreme dimensions again
yield these classical physical geodesic flows. We have already shown that this
optimal control setting gives a new symmetric representation of the rigid body
flow and in this paper we extend this representation to the geodesic flow on
the ellipsoid and the more general Stiefel manifold case. The metric we choose
on the Stiefel manifolds is the same as that used in the symmetric
representation of the rigid body flow and that used by Moser and Veselov. In
the extreme cases of the ellipsoid and the rigid body, the geodesic flows are
known to be integrable. We obtain the extremal flows using both variational and
optimal control approaches and elucidate the structure of the flows on general
Stiefel manifolds.Comment: 30 page
RHEB1 Expression in Embryonic and Postnatal Mouse
Ras homolog enriched in brain (RHEB1) is a member within the superfamily of GTP-binding proteins encoded by the RAS oncogenes. RHEB1 is located at the crossroad of several important pathways including the insulin-signaling pathways and thus plays an important role in different physiological processes. To understand better the physiological relevance of RHEB1 protein, the expres-sion pattern of RHEB1 was analyzed in both embryonic (at E3.5–E16.5) and adult (1-month old) mice. RHEB1 immu-nostaining and X-gal staining were used for wild-type and Rheb1 gene trap mutant mice, respectively. These inde-pendent methods revealed similar RHEB1 expression pat-terns during both embryonic and postnatal developments. Ubiquitous uniform RHEB1/β-gal and/or RHEB1 expres-sion was seen in preimplantation embryos at E3.5 and post-implantation embryos up to E12.5. Between stages E13.5 and E16.5, RHEB1 expression levels became complex: In particular, strong expression was identified in neural tis-sues, including the neuroepithelial layer of the mesenceph-alon, telencephalon, and neural tube of CNS and dorsal root ganglia. In addition, strong expression was seen in certain peripheral tissues including heart, intestine, muscle, and urinary bladder. Postnatal mice have broad spatial RHEB1 expression in different regions of the cerebral cortex, sub-cortical regions (including hippocampus), olfactory bulb, medulla oblongata, and cerebellum (particularly in Purkinje cells). Significant RHEB1 expression was also viewed in internal organs including the heart, intestine, urinary blad-der, and muscle. Moreover, adult animals have complex tis-sue- and organ-specific RHEB1 expression patterns with different intensities observed throughout postnatal develop-ment. Its expression level is in general comparable in CNS and other organs of mouse. Thus, the expression pattern of RHEB1 suggests that it likely plays a ubiquitous role in the development of the early embryo with more tissue-specific roles in later development
An essential bifunctional enzyme in Mycobacterium tuberculosis for itaconate dissimilation and leucine catabolism
Mycobacterium tuberculosis (Mtb) is the etiological agent of tuberculosis. One-fourth of the global population is estimated to be infected with Mtb, accounting for ∼1.3 million deaths in 2017. As part of the immune response to Mtb infection, macrophages produce metabolites with the purpose of inhibiting or killing the bacterial cell. Itaconate is an abundant host metabolite thought to be both an antimicrobial agent and a modulator of the host inflammatory response. However, the exact mode of action of itaconate remains unclear. Here, we show that Mtb has an itaconate dissimilation pathway and that the last enzyme in this pathway, Rv2498c, also participates in L-leucine catabolism. Our results from phylogenetic analysis, in vitro enzymatic assays, X-ray crystallography, and in vivo Mtb experiments, identified Mtb Rv2498c as a bifunctional β-hydroxyacyl-CoA lyase and that deletion of the rv2498c gene from the Mtb genome resulted in attenuation in a mouse infection model. Altogether, this report describes an itaconate resistance mechanism in Mtb and an L-leucine catabolic pathway that proceeds via an unprecedented (R)-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) stereospecific route in nature
Atomic spectroscopy studies of short-lived isotopes and nuclear isomer separation with the ISOLDE RILIS
The Resonance Ionization Laser Ion Source (RILIS) at the ISOLDE on-line isotope separator is based on the selective excitation of atomic transitions by tunable laser radiation. Ion beams of isotopes of 20 elements have been produced using the RILIS setup. Together with the mass separator and a particle detection system it represents a tool for high-sensitive laser spectroscopy of short-lived isotopes. By applying narrow-bandwidth lasers for the RILIS one can study isotope shifts (IS) and hyperfine structure (HFS) of atomic optical transitions. Such measurements are capable of providing data on nuclear charge radii, spins and magnetic moments of exotic nuclides far from stability. Although the Doppler broadening of the optical absorption lines limits the resolution of the technique, the accuracy of the HFS measurements examined in experiments with stable Tl isotopes approaches a value of 100 MHz. Due to the hyperfine splitting of atomic lines the RILIS gives an opportunity to separate nuclear isomers. Isomer selectivity of the RILIS has been used in studies of short-lived Ag, Cu and Pb isotopes
Conductivity of underdoped YBa2Cu3O7-d : evidence for incoherent pair correlations in the pseudogap regime
Conductivity due to superconducting fluctuations studied in optimally doped
YBa2Cu3O7-d films displays a stronger decay law in temperature than explainable
by theory. A formula is proposed, which fits the data very well with two
superconductive parameters, Tc and the coherence length ksi_c0, and an energy
scale Delta*. This is also valid in underdoped materials and enables to
describe the conductivity up to 300 K with a single-particle excitations
channel in parallel with a channel whose contribution is controlled by ksi_c0,
Tc and Delta*.
This allows to address the nature of the pseudogap in favour of incoherent
pairing.Comment: 14 pages, 4 figures, 1 tabl
A Model Study of Discrete Scale Invariance and Long-Range Interactions
We investigate the modification of discrete scale invariance in the bound
state spectrum by long-range interactions. This problem is relevant for
effective field theory descriptions of nuclear cluster states and
manifestations of the Efimov effect in nuclei. As a model system, we choose a
one dimensional inverse square potential supplemented with a long-range Coulomb
interaction. We study the renormalization and bound-state spectrum of the
system as a function of the Coulomb interaction strength. Our results indicate,
that the counterterm required to renormalize the inverse square potential alone
is sufficient to renormalize the full problem. However, the breaking of the
discrete scale invariance through the Coulomb interaction leads to a modified
bound state spectrum. The shallow bound states are strongly influenced by the
Coulomb interaction while the deep bound states are dominated by the inverse
square potential.Comment: 8 pages, 6 figures, EPJ style, published versio
The symmetric representation of the rigid body equations and their discretization
This paper analyses continuous and discrete versions of the generalized rigid body equations and the role of these equations in numerical analysis, optimal control and integrable Hamiltonian systems. In particular, we present a symmetric representation of the rigid body equations on the Cartesian product SO(n)×SO(n) and study its associated symplectic structure. We describe the relationship of these ideas with the Moser-Veselov theory of discrete integrable systems and with the theory of variational symplectic integrators. Preliminary work on the ideas discussed in this paper may be found in Bloch et al (Bloch A M, Crouch P, Marsden J E and Ratiu T S 1998 Proc. IEEE Conf. on Decision and Control 37 2249-54).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49076/2/no2416.pd
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