840 research outputs found
Influence of the Lower Hybrid Drift Instability on the onset of Magnetic Reconnection
Two-dimensional and three-dimensional kinetic simulation results reveal the
importance of the Lower-Hybrid Drift Instability LHDI to the onset of magnetic
reconnection. Both explicit and implicit kinetic simulations show that the LHDI
heats electrons anisotropically and increases the peak current density. Linear
theory predicts these modifications can increase the growth rate of the tearing
instability by almost two orders of magnitude and shift the fastest growing
modes to significantly shorter wavelengths. These predictions are confirmed by
nonlinear kinetic simulations in which the growth and coalescence of small
scale magnetic islands leads to a rapid onset of large scale reconnection
Removal of Escherichia coli in treated wastewater used for food production in Morogoro, Tanzania
Acadmic Journal Vol. 10(33), pp. 1344-1350The aim of this study was to assess the removal efficiency of Escherichia coli at Mafisa and
Mzumbe domestic wastewater treatment ponds in Morogoro, Tanzania. The study was done from
October, 2013 to April, 2014. A total of 125 water samples from inlets and subsequent anaerobic,
facultative and maturation ponds as well as treated wastewater were collected and analysed for E.
coli. The estimated retention times of the wastewater treatment units were 19 and 22 days in Mafisa
and Mzumbe ponds, respectively. The concentration of E. coli ranged from 4.70 to 5.60 log cfu/mL in
untreated wastewater and was reduced to <1.00 to 2.00 log cfu/mL in the treated wastewater. During
rainy and cold seasons, the effluent discharged out at Mafisa during August 2013; and March and
April, 2014 was about 2 log cfu/mL while at Mzumbe E. coli concentration in effluent discharged out
was up to 1.23 log cfu/mL. The concentration of E. coli in untreated and treated wastewater from the
two wastewater treatment ponds study sites were comparable (P<0.05). Reduction of E. coli
concentration in wastewater treatment ponds study sites was significant with less reduction seen at
Mafisa, during rainy and cold seasons in March, April and August. To conclude, the simple
wastewater treatment ponds in the study sites were effective and demonstrated potential for
reduction of public health risks associated with use of treated wastewater in agricultural irrigation
and aquaculture
Oxidative DNA damage stalls the human mitochondrial replisome
Oxidative stress is capable of causing damage to various cellular constituents, including DNA. There is however limited knowledge on how oxidative stress influences mitochondrial DNA and its replication. Here, we have used purified mtDNA replication proteins, i.e. DNA polymerase γ holoenzyme, the mitochondrial single-stranded DNA binding protein mtSSB, the replicative helicase Twinkle and the proposed mitochondrial translesion synthesis polymerase PrimPol to study lesion bypass synthesis on oxidative damage-containing DNA templates. Our studies were carried out at dNTP levels representative of those prevailing either in cycling or in non-dividing cells. At dNTP concentrations that mimic those in cycling cells, the replication machinery showed substantial stalling at sites of damage, and these problems were further exacerbated at the lower dNTP concentrations present in resting cells. PrimPol, the translesion synthesis polymerase identified inside mammalian mitochondria, did not promote mtDNA replication fork bypass of the damage. This argues against a conventional role for PrimPol as a mitochondrial translesion synthesis DNA polymerase for oxidative DNA damage; however, we show that Twinkle, the mtDNA replicative helicase, is able to stimulate PrimPol DNA synthesis in vitro, suggestive of an as yet unidentified role of PrimPol in mtDNA metabolism
Faecal contamination and health aspects of processing tomatoes (<em>Solanum lycopersicum</em>) irrigated with wastewater treated by decentralised wastewater treatment technologies
Cosmic Ray Acceleration by Spiral Shocks in the Galactic Wind
Cosmic ray acceleration by shocks related with Slipping Interaction Regions
(SIRs) in the Galactic Wind is considered. SIRs are similar to Solar Wind
Corotating Interaction Regions. The spiral structure of our Galaxy results in a
strong nonuniformity of the Galactic Wind flow and in SIR formation at
distances of 50 to 100 kpc. SIRs are not corotating with the gas and magnetic
field because the angular velocity of the spiral pattern differs from that of
the Galactic rotation. It is shown that the collective reacceleration of the
cosmic ray particles with charge in the resulting shock ensemble can
explain the observable cosmic ray spectrum beyond the "knee" up to energies of
the order of eV. For the reaccelerated particles the Galactic Wind
termination shock acts as a reflecting boundary.Comment: LATEX, 14 pages, 7 figures, accepted to A&
Three-Dimensional Fermi Surface of Overdoped La-Based Cuprates
We present a soft x-ray angle-resolved photoemission spectroscopy study of
the overdoped high-temperature superconductors LaSrCuO and
LaEuSrCuO. In-plane and out-of-plane components of
the Fermi surface are mapped by varying the photoemission angle and the
incident photon energy. No dispersion is observed along the nodal
direction, whereas a significant antinodal dispersion is identified.
Based on a tight-binding parametrization, we discuss the implications for the
density of states near the van-Hove singularity. Our results suggest that the
large electronic specific heat found in overdoped LaSrCuO can
not be assigned to the van-Hove singularity alone. We therefore propose quantum
criticality induced by a collapsing pseudogap phase as a plausible explanation
for observed enhancement of electronic specific heat
Confirming the high pressure phase diagram of the Shastry-Sutherland model
A Muon Spin Rotation (μ + SR) study was conducted to investigate the magnetic properties of SrCu2(BO3)2 (SCBO) as a function of temperature/pressure. Measurements in zero field and transverse field confirm the absence of long range magnetic order at high pressures and low temperatures. These measurements suggest changes in the Cu spin fluctuations characteristics above 21 kbar, consistent with the formation of a plaquette phase as previously suggested by inelastic neutron scattering measurements. SCBO is the only known realisation of the Shatry-Sutherland model, thus the ground state mediating the dimer and antiferromagnetic phase is likekly to be a plaquette state
Neutron powder diffraction study of NaMnO and LiMnO: New insights on spin-charge-orbital ordering
The high-pressure synthesized quasi-one-dimensional compounds NaMnO
and LiMnO are both antiferromagnetic insulators, and here
their atomic and magnetic structures were investigated using neutron powder
diffraction. The present crystal structural analyses of NaMn2O4 reveal that
Mn3+/Mn4+ charge-ordering state exist even at low temperature (down to 1.5 K).
It is evident from one of the Mn sites shows a strongly distorted Mn3+
octahedra due to the Jahn-Teller effect. Above TN = 39 K, a two-dimensional
short-range correlation is observed, as indicated by an asymmetric diffuse
scattering. Below TN, two antiferromagnetic transitions are observed (i) a
commensurate long-range Mn3+ spin ordering below 39 K, and (ii) an
incommensurate Mn4+ spin ordering below 10 K. The commensurate magnetic
structure (kC = 0.5, -0.5, 0.5) follows the magnetic anisotropy of the local
easy axes of Mn3+, while the incommensurate one shows a spin-density-wave order
with kIC = (0,0,0.216). For LiMnO, on the other hand, absence
of a long-range spin ordered state down to 1.5 K is confirmed.Comment: 11 pages, 8 figure
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Rural telemedicine project in northern New Mexico
A virtual electronic medical record system is being deployed over the Internet with security in northern New Mexico using TeleMed, a multimedia medical records management system that uses CORBA-based client-server technology and distributed database architecture. The goal of the NNM Rural Telemedicine Project is to implement TeleMed into fifteen rural clinics and two hospitals within a 25,000 square mile area of northern New Mexico. Evaluation of the project consists of three components: job task analysis, audit of immunized children, and time motion studies. Preliminary results of the evaluation components are presented
Role of surface roughness in hard x-ray emission from femtosecond laser produced copper plasmas
The hard x-ray emission in the energy range of 30-300 keV from copper plasmas
produced by 100 fs, 806 nm laser pulses at intensities in the range of
10 W cm is investigated. We demonstrate that surface
roughness of the targets overrides the role of polarization state in the
coupling of light to the plasma. We further show that surface roughness has a
significant role in enhancing the x-ray emission in the above mentioned energy
range.Comment: 5 pages, 4 figures, to appear in Phys. Rev.
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