2,940 research outputs found
Analytical treatment of SUSY Quasi-normal modes in a non-rotating Schwarzschild black hole
We use the Fock-Ivanenko formalism to obtain the Dirac equation which
describes the interaction of a massless 1/2-spin neutral fermion with a
gravitational field around a Schwarzschild black hole (BH). We obtain
approximated analytical solutions for the eigenvalues of the energy
(quasi-normal frequencies) and their corresponding eigenstates (quasi-normal
states). The interesting result is that all the excited states [and their
supersymmetric (SUSY) partners] have a purely imaginary frequency, which can be
expressed in terms of the Hawking temperature. Furthermore, as one expects for
SUSY Hamiltonians, the isolated bottom state has a real null energy eigenvalue.Comment: Version to be published in European Physical Journal
CQESTR Simulation of Management Practice Effects on Long-Term Soil Organic Carbon
Management of soil organic matter (SOM) is important for soil productivity and responsible utilization of crop residues for additional uses. CQESTR, pronounced “sequester,” a contraction of “C sequestration” (meaning C storage), is a C balance model that relates organic residue additions, crop management, and soil tillage to SOM accretion or loss. Our objective was to simulate SOM changes in agricultural soils under a range of climate and management systems using the CQESTR model. Four long-term experiments (Champaign, IL, \u3e100 yr; Columbia, MO, \u3e100 yr; Lincoln, NE, 20 yr; Sidney, NE, 20 yr) in the United States under various crop rotations, tillage practices, organic amendments, and crop residue removal treatments were selected for their documented history of the long-term effects of management practice on SOM dynamics. CQESTR successfully simulated a substantial decline in SOM with 50 yr of crop residue removal under various rotations at Columbia and Champaign. The increase in SOM following addition of manure was simulated well; however, the model underestimated SOM for a fertilized treatment at Columbia. Predicted and observed values from the four sites were signifi cantly related (r2 = 0.94, n = 113, P \u3c 0.001), with slope not signifi cantly different from 1. Given the high correlation of simulated and observed SOM changes, CQESTR can be used as a reliable tool to predict SOM changes from management practices and offers the potential for estimating soil C storage required for C credits. It can also be an important tool to estimate the impacts of crop residue removal for bioenergy production on SOM level and soil production capacity
HEAT TRANSFER TO IMMERSED COOLING TUBES AND PARTICLES IN A FLUIDIZED BED REACTOR
A simple heat transfer model is utilized to determine the heat transfer coefficients for multiple tubes immersed in an industrial fluidized bed reactor supporting an exothermic reaction. From the temperatures at their outlets, superheating occurs in some blocks of tubes, but not in others. A four-zone heat transfer model is then used to evaluate the axial and lateral temperature differences due to the existence of a bottom un-cooled entrance zone and two cooled zones, corresponding to the regions where superheating does and does not occur
Cystic meningioangiomatosis with enhancing mural nodule on MRI and no calcification on CT
The neuroradiological features of meningioangiomatosis (MA) are non-specific. We report a young man with sporadic MA. The plain computerized tomography (CT) demonstrated a deep located right cystic lesion without calcification. On magnetic resonance imaging, the cystic mass lesion was confirmed with a mural nodule with significant enhancement on contrast-enhanced images
Single-cell genomic analysis in plants
Individual cells in an organism are variable, which strongly impacts cellular processes. Advances in sequencing technologies have enabled single-cell genomic analysis to become widespread, addressing shortcomings of analyses conducted on populations of bulk cells. While the field of single-cell plant genomics is in its infancy, there is great potential to gain insights into cell lineage and functional cell types to help understand complex cellular interactions in plants. In this review, we discuss current approaches for single-cell plant genomic analysis, with a focus on single-cell isolation, DNA amplification, next-generation sequencing, and bioinformatics analysis. We outline the technical challenges of analysing material from a single plant cell, and then examine applications of single-cell genomics and the integration of this approach with genome editing. Finally, we indicate future directions we expect in the rapidly developing field of plant single-cell genomic analysis
Professor David Minnikin Memorial Lecture:An era of the mycobacterial cell wall lipid biomarkers
This paper is dedicated to the memory of Professor David Ernest Minnikin (1939–2021). David was one of the key scientists who pioneered the field of Mycobacterium tuberculosis cell envelope research for over half a century. From the classification, identification, and extraction of the unusual lipids of the mycobacterial cell wall, to exploiting them as characteristic lipid biomarkers for sensitive detection, his ideas enlightened a whole world of possibilities within the tuberculosis (TB) field. In addition, his definition of the intricate models now forms a key milestone in our understanding of the M. tuberculosis cell envelope and has resolved many unanswered questions on the evolution of M. tuberculosis
Twist Symmetry and Classical Solutions in Open String Field Theory
We construct classical solutions of open string field theory which are not
invariant under ordinary twist operation. From detailed analysis of the moduli
space of the solutions, it turns out that our solutions become nontrivial at
boundaries of the moduli space. The cohomology of the modified BRST operator
and the CSFT potential evaluated by the level truncation method strongly
support the fact that our nontrivial solutions correspond to the closed string
vacuum. We show that the nontrivial solutions are equivalent to the twist even
solution which was found by Takahashi and Tanimoto, and twist invariance of
open string field theory remains after the shift of the classical backgrounds.Comment: 19 pages, 2 figures; v2: errors fixe
Numerical solution of an inverse problem of determining the parameters of a source of groundwater pollution
The article deals with an inverse problem of determining parameters of groundwater pollution sources. We test three ways to solve the problem on the simulated data for a simple case of contamination. We discover that, in the presence of noise in the data of the inverse problem, the first method does not produce satisfactory recovery results, while the second and third ones are comparable in accuracy of the recovery of required parameters. Taking into account the ease of implementation, the speed of computing and parallelization feasibility the second method of solving the inverse problem is found to be most preferable. We also propose a method of finding pollution parameters in general case..
Asymmetric neutrino emission due to neutrino-nucleon scatterings in supernova magnetic fields
We derive the cross section of neutrino-nucleon scatterings in supernova
magnetic fields, including weak-magnetism and recoil corrections. Since the
weak interaction violates the parity, the scattering cross section
asymmetrically depends on the directions of the neutrino momenta to the
magnetic field; the origin of pulsar kicks may be explained by the mechanism.
An asymmetric neutrino emission (a drift flux) due to neutrino-nucleon
scatterings is absent at the leading level of , where
is the nucleon magneton, is the magnetic field strength, and is
the matter temperature at a neutrinosphere. This is because at this level the
drift flux of the neutrinos are exactly canceled by that of the antineutrinos.
Hence, the relevant asymmetry in the neutrino emission is suppressed by much
smaller coefficient of , where is the nucleon mass;
detailed form of the relevant drift flux is also derived from the scattering
cross section, using a simple diffusion approximation. It appears that the
asymmetric neutrino emission is too small to induce the observed pulsar kicks.
However, we note the fact that the drift flux is proportional to the deviation
of the neutrino distribution function from the value of thermal equilibrium at
neutrinosphere. Since the deviation can be large for non-electron neutrinos, it
is expected that there occurs cancellation between the deviation and the small
suppression factor of . Using a simple parameterization,
we show that the drift flux due to neutrino-nucleon scatterings may be
comparable to the leading term due to beta processes with nucleons, which has
been estimated to give a relevant kick velocity when the magnetic field is
sufficiently strong as -- G.Comment: 19 pages, 1 figure. Accepted by Physical Review
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