652 research outputs found
Isolation of Glyoxysomes from Pumpkin Cotyledons
Peroxisomes are singleâ membraneâ bound organelles found in virtually all eukaryotes. In plants, there are several classes of peroxisomes. Glyoxysomes are found in germinating seedlings and contain enzymes specific for the glyoxylate cycle, including isocitrate lyase and malate synthase. After seedlings become photosynthetic, leaf peroxisomes participate in reactions of the photorespiration pathway and contain characteristic enzymes such as glycolate oxidase and hydroxypyruvate reductase. As leaves begin to senesce, leaf peroxisomes are transformed back into glyoxysomes. Root peroxisomes in the nodules of legumes, for example, sequester enzymes such as allantoinase and uricase, which contribute to nitrogen metabolism in these tissues. Thus, peroxisomes participate in many metabolic pathways and contain specific enzyme complements, depending on the tissue source. All peroxisomes contain catalase to degrade hydrogen peroxide and enzymes to accomplish βâ oxidation of fatty acids. Glyoxysomes can be isolated from pumpkin cotyledons by standard differential centrifugation and density separation, as described in this article.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143713/1/cpcb0319.pd
Exact solutions of Dirac equation on (1+1)-dimensional spacetime coupled to a static scalar field
We use a generalized scheme of supersymmetric quantum mechanics to obtain the
energy spectrum and wave function for Dirac equation in (1+1)-dimensional
spacetime coupled to a static scalar field.Comment: 7 pages, Late
Metabolomics reveals distinct neurochemical profiles associated with stress resilience
Acute social defeat represents a naturalistic form of conditioned fear and is an excellent model in which to investigate the biological basis of stress resilience. While there is growing interest in identifying biomarkers of stress resilience, until recently, it has not been feasible to associate levels of large numbers of neurochemicals and metabolites to stress-related phenotypes. The objective of the present study was to use an untargeted metabolomics approach to identify known and unknown neurochemicals in select brain regions that distinguish susceptible and resistant individuals in two rodent models of acute social defeat. In the first experiment, male mice were first phenotyped as resistant or susceptible. Then, mice were subjected to acute social defeat, and tissues were immediately collected from the ventromedial prefrontal cortex (vmPFC), basolateral/central amygdala (BLA/CeA), nucleus accumbens (NAc), and dorsal hippocampus (dHPC). Ultra-high performance liquid chromatography coupled with high resolution mass spectrometry (UPLC-HRMS) was used for the detection of water-soluble neurochemicals. In the second experiment, male Syrian hamsters were paired in daily agonistic encounters for 2 weeks, during which they formed stable dominant-subordinate relationships. Then, 24 h after the last dominance encounter, animals were exposed to acute social defeat stress. Immediately after social defeat, tissue was collected from the vmPFC, BLA/CeA, NAc, and dHPC for analysis using UPLC-HRMS. Although no single biomarker characterized stress-related phenotypes in both species, commonalities were found. For instance, in both model systems, animals resistant to social defeat stress also show increased concentration of molecules to protect against oxidative stress in the NAc and vmPFC. Additionally, in both mice and hamsters, unidentified spectral features were preliminarily annotated as potential targets for future experiments. Overall, these findings suggest that a metabolomics approach can identify functional groups of neurochemicals that may serve as novel targets for the diagnosis, treatment, or prevention of stress-related mental illness
Space-time evolution of ultra-relativistic heavy ion collisions and hadronic spectra
The space-time evolution of the hot and dense matter formed after the
collisions of heavy nuclei at ultra-relativistic energies is investigated using
(3+1) dimensional hydrodynamical models. The effects of the spectral shift of
the hadronic properties are incorporated in the equation of state (EOS) of the
evolving matter. In-medium shift of hadronic properties are considered for
Quantum Hadrodynamics (QHD) and universal scaling scenarios. It is found that
the EOS for the hadronic matter for universal scaling of hadronic masses
(except pseudoscalar mesons) is similar to the recent lattice results. We
observe that the space-time volume of the hadronic matter at the freeze-out is
considerably different from the one when medium effects on the hadrons are
ignored. The sensitivity of the results on the initial radial velocity profile
is investigated. The transverse mass spectra of pions and protons of NA49
collaboration are analyzed.Comment: Total 17 pages with 18 figure
Nucleation versus Spinodal decomposition in a first order quark hadron phase transition
We investigate the scenario of homogeneous nucleation for a first order
quark-hadron phase transition in a rapidly expanding background of quark gluon
plasma. Using an improved preexponential factor for homogeneous nucleation
rate, we solve a set of coupled equations to study the hadronization and the
hydrodynamical evolution of the matter. It is found that significant
supercooling is possible before hadronization begins. This study also suggests
that spinodal decomposition competes with nucleation and may provide an
alternative mechanism for phase conversion particularly if the transition is
strong enough and the medium is nonviscous. For weak enough transition, the
phase conversion may still proceed via homogeneous nucleation.Comment: LaTeX, 10 pages with 7 Postscript figures, more discussions and
referencese added, typos correcte
Modern topics in theoretical nuclear physics
Over the past five years there have been profound advances in nuclear physics
based on effective field theory and the renormalization group. In this brief,
we summarize these advances and discuss how they impact our understanding of
nuclear systems and experiments that seek to unravel their unknowns. We discuss
future opportunities and focus on modern topics in low-energy nuclear physics,
with special attention to the strong connections to many-body atomic and
condensed matter physics, as well as to astrophysics. This makes it an exciting
era for nuclear physics.Comment: 8 pages, 1 figure, prepared for the Nuclear Physics Town Hall Meeting
at TRIUMF, Sept. 9-10, 2005, comments welcome, references adde
- and -hypernuclei
- and -hypernuclei are studied in the quark-meson
coupling (QMC) model. Comparisons are made with the results for
-hypernuclei studied in the same model previously. Although the scalar
and vector potentials felt by the , and in
the corresponding hypernuclei multiplet which has the same baryon numbers are
quite similar, the wave functions obtained, e.g., for state, are
very different. The baryon density distribution in
Pb is much more pushed away from the center than that for
the in Pb due to the Coulomb force. On the contrary,
the baryon density distributions in -hypernuclei are
much larger near the origin than those for the in the corresponding
-hypernuclei due to its heavy mass. It is also found that level
spacing for the single-particle energies is much smaller than that
for the and .Comment: Latex, 14 pages, 4 figures, text was extended, version to appear in
Phys. Rev.
Observing many body effects on lepton pair production from low mass enhancement and flow at RHIC and LHC energies
The spectral function at finite temperature calculated using the
real-time formalism of thermal field theory is used to evaluate the low mass
dilepton spectra. The analytic structure of the propagator is studied
and contributions to the dilepton yield in the region below the bare
peak from the different cuts in the spectral function are discussed. The
space-time integrated yield shows significant enhancement in the region below
the bare peak in the invariant mass spectra. It is argued that the
variation of the inverse slope of the transverse mass () distribution can
be used as an efficient tool to predict the presence of two different phases of
the matter during the evolution of the system. Sensitivity of the effective
temperature obtained from the slopes of the spectra to the medium effects
are studied
Constraints on Nucleus Dynamics from Dirac Phenomenology of Atoms
Strong interaction level shifts and widths in atoms are analyzed
by using a nucleus optical potential constructed within the
relativistic mean field approach. The analysis leads to potentials with a
repulsive real part in the nuclear interior. The data are sufficient to
establish the size of the isovector meson--hyperon coupling. Implications to
hypernuclei are discussed.Comment: 18 pages, RevTex, 4 uuencoded figures, subm. Nucl.Phys.
Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
Extensive experimental data from high-energy nucleus-nucleus collisions were
recorded using the PHENIX detector at the Relativistic Heavy Ion Collider
(RHIC). The comprehensive set of measurements from the first three years of
RHIC operation includes charged particle multiplicities, transverse energy,
yield ratios and spectra of identified hadrons in a wide range of transverse
momenta (p_T), elliptic flow, two-particle correlations, non-statistical
fluctuations, and suppression of particle production at high p_T. The results
are examined with an emphasis on implications for the formation of a new state
of dense matter. We find that the state of matter created at RHIC cannot be
described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted
to Nuclear Physics A as a regular article; v3 has minor changes in response
to referee comments. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
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