243 research outputs found
Compact Inverses of The Multipoint Normal Diferential Operators For First Order
In this work, firstly all normal extensions of a multipoint minimal operator
generated by linear multipoint diferential-operator expression for first order
in the Hilbert space of vector functions in terms of boundary values at the
endpoints of the infinitely many separated subintervals are described. Finally,
a compactness properties of the inverses of such extensions has been
investigated.Comment: 9 page
Spectrum of the Direct Sum of Operators
In this work, a connection between some spectral properties of direct sum of
operators in the direct sum of Hilbert spaces and its coordinate operators has
been investigated.Comment: 10 page
Effect of Aging Treatment on Surface Roughness, Mechanical Properties, and Fracture Behavior of 6xxx and 7xxx Aluminum Alloys
The effect of aging treatment on the surface
roughness and mechanical properties of AA6061
and AA7075 alloys was studied. Microhardness
and tensile tests were used to investigae the mechanical
properties. X-ray diffraction analysis
was used to investigate the surface of the specimens.
Furthermore, after tensile tests fractured
surfaces were examined with scanning electron
microscopy. An atomic force microscope was
employed for analysis of the effect of aging
treatment on surface roughness. Higher surface
roughness with an increase in the volume fraction
of the precipitate was revealed.Исследовано влияние процесса старения на шероховатость поверхности и механические
свойства алюминиевых сплавов AA6061 и AA7075. Механические свойства исследовали при
испытаниях на микротвердость и растяжение. Поверхность образцов исследовали с помощью рентгеноструктурного анализа. После испытания на растяжение поверхность разрушения исследовали методом растровой электронной микроскопии. Влияние процесса старения
на шероховатость поверхности изучали с помощью атомно-силового микроскопа. Показано,
что с ростом шероховатости поверхности увеличивается количество выделившихся фаз.Досліджено вплив процесу старіння на шорсткість поверхні і механічні властивості
алюмінієвих сплавів АА6061 та АА7075. Механічні властивості досліджували при
випробуваннях на мікротвердість і розтяг. Поверхню зразків досліджували за допомогою рентгеноструктурного аналізу. Після випробувань на розтяг поверхню руйнування досліджували методом растрової електронної мікроскопії. Вплив процесу
старіння на шорсткість поверхні вивчали за допомогою атомно-силового мікроскопа.
Показано, що з ростом шорсткості поверхні збільшується кількість виділених фа
Source apportionment of fine particulate matter in Houston, Texas: insights to secondary organic aerosols
Online and offline measurements of ambient particulate matter (PM) near the
urban and industrial Houston Ship Channel in Houston, Texas, USA, during May
2015 were utilized to characterize its chemical composition and to evaluate
the relative contributions of primary, secondary, biogenic, and anthropogenic
sources. Aerosol mass spectrometry (AMS) on nonrefractory PM1 (PM ≤
1 µm) indicated major contributions from sulfate (averaging
50 % by mass), organic aerosol (OA, 40 %), and ammonium (14 %).
Positive matrix factorization (PMF) of AMS data categorized OA on average as
22 % hydrocarbon-like organic aerosol (HOA), 29 % cooking-influenced
less-oxidized oxygenated organic aerosol (CI-LO-OOA), and 48 %
more-oxidized oxygenated organic aerosol (MO-OOA), with the latter two
sources indicative of secondary organic aerosol (SOA). Chemical analysis of
PM2.5 (PM ≤ 2.5 µm) filter samples agreed that organic
matter (35 %) and sulfate (21 %) were the most abundant components.
Organic speciation of PM2.5 organic carbon (OC) focused on molecular
markers of primary sources and SOA tracers derived from biogenic and
anthropogenic volatile organic compounds (VOCs). The sources of PM2.5 OC
were estimated using molecular marker-based positive matric factorization
(MM-PMF) and chemical mass balance (CMB) models. MM-PMF resolved nine factors
that were identified as diesel engines (11.5 %), gasoline engines
(24.3 %), nontailpipe vehicle emissions (11.1 %), ship emissions
(2.2 %), cooking (1.0 %), biomass burning (BB, 10.6 %), isoprene
SOA (11.0 %), high-NOx anthropogenic SOA (6.6 %),
and low-NOx anthropogenic SOA (21.7 %). Using available
source profiles, CMB apportioned 41 % of OC to primary fossil sources
(gasoline engines, diesel engines, and ship emissions), 5 % to BB,
15 % to SOA (including 7.4 % biogenic and 7.6 % anthropogenic),
and 39 % to other sources that were not included in the model and are
expected to be secondary.This study presents the first application of in situ AMS-PMF, MM-PMF, and
CMB for OC source apportionment and the integration of these methods to
evaluate the relative roles of biogenic, anthropogenic, and BB-SOA. The three
source apportionment models agreed that ∼  50 % of OC is associated
with primary emissions from fossil fuel use, particularly motor vehicles.
Differences among the models reflect their ability to resolve sources based
upon the input chemical measurements, with molecular marker-based methods
providing greater source specificity and resolution for minor sources. By
combining results from MM-PMF and CMB, BB was estimated to contribute
11 % of OC, with 5 % primary emissions and 6 % BB-SOA. SOA was
dominantly anthropogenic (28 %) rather than biogenic (11 %) or
BB-derived. The three-model approach
demonstrates significant contributions of anthropogenic SOA to fine PM. More
broadly, the findings and methodologies presented herein can be used to
advance local and regional understanding of anthropogenic contributions to
SOA.</p
A FRUITFULL-like gene is associated with genetic variation for fruit flesh firmness in apple (Malus domestica Borkh.)
The FRUITFULL (FUL) and SHATTERPROOF (SHP) genes are involved in regulating fruit development and dehiscence in Arabidopsis. We tested the hypothesis that this class of genes are also involved in regulating the development of fleshy fruits, by exploring genetic and phenotypic variation within the apple (Malus domestica) gene pool. We isolated and characterised the genomic sequences of two candidate orthologous FUL-like genes, MdMADS2.1 and MdMADS2.2. These were mapped using the reference population ‘Prima x Fiesta’ to loci on Malus linkage groups LG14 and LG06, respectively. An additional MADS-box gene, MdMADS14, shares high amino acid identity with the Arabidopsis SHATTERPROOF1/2 genes and was mapped to Malus linkage group LG09. Association analysis between quantitative fruit flesh firmness estimates of ‘Prima x Fiesta’ progeny and the MdMADS2.1, MdMADS2.2 and MdMADS14 loci was carried out using a mixed model analysis of variance. This revealed a significant association (P < 0.01) between MdMADS2.1 and fruit flesh firmness. Further evidence for the association between MdMADS2.1 and fruit flesh firmness was obtained using a case–control population-based genetic association approach. For this, a polymorphic repeat, (AT)n, in the 3′ UTR of MdMADS2.1 was used as a locus-specific marker to screen 168 apple accessions for which historical assessments of fruit texture attributes were available. This analysis revealed a significant association between the MdMADS2.1 and fruit flesh firmness at both allelic (χ 2 = 34, df = 9, P < 0.001) and genotypic (χ 2 = 57, df = 32, P < 0.01) levels
Bioenergetics Failure and Oxidative Stress in Brain Stem Mediates Cardiovascular Collapse Associated with Fatal Methamphetamine Intoxication
Background: Whereas sudden death, most often associated with cardiovascular collapse, occurs in abusers of the psychostimulant methamphetamine (METH), the underlying mechanism is much less understood. The demonstration that successful resuscitation of an arrested heart depends on maintained functionality of the rostral ventrolateral medulla (RVLM), which is responsible for the maintenance of stable blood pressure, suggests that failure of brain stem cardiovascular regulation, rather than the heart, holds the key to cardiovascular collapse. We tested the hypothesis that cessation of brain stem cardiovascular regulation because of a loss of functionality in RVLM mediated by bioenergetics failure and oxidative stress underlies the cardiovascular collapse elicited by lethal doses of METH. Methodology/Principal Findings: Survival rate, cardiovascular responses and biochemical or morphological changes in RVLM induced by intravenous administration of METH in Sprague-Dawley rats were investigated. High doses of METH induced significant mortality within 20 min that paralleled concomitant the collapse of arterial pressure or heart rate and loss of functionality in RVLM. There were concurrent increases in the concentration of METH in serum and ventrolateral medulla, along with tissue anoxia, cessation of microvascular perfusion and necrotic cell death in RVLM. Furthermore, mitochondrial respiratory chain enzyme activity or electron transport capacity and ATP production in RVLM were reduced, and mitochondria-derived superoxide anion level was augmented. All those detrimental physiological and biochemica
Neuronal Deletion of Caspase 8 Protects against Brain Injury in Mouse Models of Controlled Cortical Impact and Kainic Acid-Induced Excitotoxicity
system. mice demonstrated superior survival, reduced seizure severity, less apoptosis, and reduced caspase 3 processing. Uninjured aged knockout mice showed improved learning and memory, implicating a possible role for caspase 8 in cognitive decline with aging.Neuron-specific deletion of caspase 8 reduces brain damage and improves post-traumatic functional outcomes, suggesting an important role for this caspase in pathophysiology of acute brain trauma
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