2,773 research outputs found
Early-Season Phenology and Temporal Dynamics of the Common Asparagus Beetle, \u3ci\u3eCrioceris Asparagi\u3c/i\u3e (Coleoptera: Chrysomelidae), in Southern Minnesota
During the years 1991-1994, studies were conducted to determine the early-season phenology and temporal dynamics of Crioceris asparagi (L.) (Co- leoptera: Chrysomelidae) in southern Minnesota asparagus. To document the early-season phenology, asparagus plots were sampled for egg, larval, and adult stages of C. asparagi during the months of May and June. Temporal dynamics of C. asparagi were determined by measuring the diurnal activity of adults and sampling asparagus plots at specific times (7 am, 9 am, 11 am, 1 pm, 3 pm and 5 pm) throughout May and June. We first detected C. asparagi adults in early May and they remained active throughout the sampling period. Eggs and larvae were also found; larval infestations on spears, however, were consistently lower than those for eggs. The temporal dynamics of C. asparagi adults showed that a higher percentage of asparagus plants were observed to be infested with beetles during the afternoon hours of 1 and 5 pm. The information provided in this paper illustrates the importance of determining the optimum time of day for sampling and will assist in properly targeting sampling efforts in future asparagus research and integrated pest management (IPM) programs
Quasar 3C 298: a test-case for meteoritic nanodiamond 3.5 µm emission
Aims. We calculate the dust emission expected at 3.43 and 3.53 µm if meteoritic (i.e. hydrogenated) nanodiamonds are responsible for most of the far-UV break observed in quasars.
Methods. We integrate the UV flux that hydrogenated nanodiamonds must absorb to reproduce the far-UV break. Based on laboratory spectra of H-terminated diamond surfaces, we analyse the radiative energy budget and derive theoretically the IR emission profiles expected for possible C-H surface stretch modes of the diamonds.
Results. Using as test case a spectrum of 3C 298 provided by the Spitzer Observatory, we do not find evidence of these emission bands.
Conclusions. While diamonds without surface adsorbates remain a viable candidate for explaining the far-UV break observed in quasars, hydrogenated nanodiamonds appear to be ruled out, as they would give rise to IR emission bands, which have not been observed so far
Ibuprofen Ameliorates Fatigue- And Depressive-Like Behavior in Tumor-Bearing Mice
Aims: Cancer-related fatigue (CRF) is often accompanied by depressed mood, both of which reduce functional status and quality of life. Research suggests that increased expression of pro-inflammatory cytokines is associated with skeletal muscle wasting and depressive- and fatigue-like behaviors in rodents and cancer patients. We have previously shown that treatment with ibuprofen, a nonsteroidal anti-inflammatory drug, preserved muscle mass in tumor-bearing mice. Therefore, the purpose of the present study was to determine the behavioral effects of ibuprofen in a mouse model of CRF.
Main methods: Mice were injected with colon-26 adenocarcinoma cells and treated with ibuprofen (10 mg/kg) in the drinking water. Depressive-like behavior was determined using the forced swim test (FST). Fatigue-like behaviors were determined using voluntary wheel running activity (VWRA) and grip strength. The hippocampus, gastrocnemius muscle, and serum were collected for cytokine analysis.
Key findings: Tumor-bearing mice showed depressive-like behavior in the FST, which was not observed in mice treated with ibuprofen. VWRA and grip strength declined in tumor-bearing mice, and ibuprofen attenuated this decline. Tumor-bearing mice had decreased gastrocnemius muscle mass and increased expression of IL-6, MAFBx and MuRF mRNA, biomarkers of protein degradation, in the muscle. Expression of IL-1β and IL-6 was also increased in the hippocampus. Treatment with ibuprofen improved muscle mass and reduced cytokine expression in both the muscle and hippocampus of tumor-bearing mice.
Significance: Ibuprofen treatment reduced skeletal muscle wasting, inflammation in the brain, and fatigue- and depressive-like behavior in tumor-bearing mice. Therefore, ibuprofen warrants evaluation as an adjuvant treatment for CRF
Tumor Growth Increases Neuroinflammation, Fatigue and Depressive-like Behavior Prior to Alterations in Muscle Function
Cancer patients frequently suffer from fatigue, a complex syndrome associated with loss of muscle mass, weakness, and depressed mood. Cancer-related fatigue (CRF) can be present at the time of diagnosis, during treatment, and persists for years after treatment. CRF negatively influences quality of life, limits functional independence, and is associated with decreased survival in patients with incurable disease. Currently there are no effective treatments to reduce CRF. The aim of this study was to use a mouse model of tumor growth and discriminate between two main components of fatigue: loss of muscle mass/function and altered mood/motivation. Here we show that tumor growth increased fatigue- and depressive-like behaviors, and reduced body and muscle mass. Decreased voluntary wheel running activity (VWRA) and increased depressive-like behavior in the forced swim and sucrose preference tests were evident in tumor-bearing mice within the first two weeks of tumor growth and preceded the loss of body and muscle mass. At three weeks, tumor-bearing mice had reduced grip strength but this was not associated with altered expression of myosin isoforms or impaired contractile properties of muscles. These increases in fatigue and depressive-like behaviors were paralleled by increased expression of IL-1β mRNA in the cortex and hippocampus. Minocycline administration reduced tumor-induced expression of IL-1β in the brain, reduced depressive-like behavior, and improved grip strength without altering muscle mass. Taken together, these results indicate that neuroinflammation and depressed mood, rather than muscle wasting, contribute to decreased voluntary activity and precede major changes in muscle contractile properties with tumor growth
Fluoxetine Prevents the Development of Depressive-like Behavior in a Mouse Model of Cancer Related Fatigue
Cancer patients frequently suffer from fatigue, a complex syndrome associated with tiredness and depressed mood. Cancer-related fatigue (CRF) can be present at the time of diagnosis, escalates during treatment, and can persist for years after treatment. CRF negatively influences quality of life, limits functional independence, and is associated with decreased survival in patients with incurable disease. We have previously shown that increased pro-inflammatory cytokine expression in the brain contributes to depressive- and fatigue-like behaviors in a mouse model of CRF. Inflammatory cytokines increase the activity of indoleamine 2,3-dioxygenase (IDO) and kynurenine 3-monooxygenase (KMO), which competitively reduce serotonin synthesis. Reduced serotonin availability in the brain and increased production of alternative neuroactive metabolites of tryptophan are thought to contribute to the development of depression and fatigue. The purpose of this study was to determine the effects of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), on brain cytokines and behavioral measures of fatigue and depression in tumor-bearing mice. Here we show that tumor growth increased brain expression of pro-inflammatory cytokines and KMO. Treatment with fluoxetine had no effect on tumor growth, muscle wasting, fatigue behavior, or cytokine expression in the brain. Fluoxetine, however, reduced depressive-like behaviors in tumor bearing mice. In conclusion, our data confirm that increased brain expression of pro-inflammatory cytokines is associated with tumor-induced fatigue- and depressive-like behaviors. However, it is possible to separate the effects of tumor growth on mood and fatigue-like behaviors using SSRIs such as fluoxetine
JHK Observations of Faint Standard Stars in the Mauna Kea Near-Infrared Photometric System
JHK photometry in the Mauna Kea Observatory (MKO) near-IR system is presented
for 115 stars. Of these, 79 are UKIRT standards and 42 are LCO standards. The
average brightness is 11.5 mag, with a range of 10 to 15. The average number of
nights each star was observed is 4, and the average of the internal error of
the final results is 0.011 mag. These JHK data agree with those reported by
other groups to 0.02 mag. The measurements are used to derive transformations
between the MKO JHK photometric system and the UKIRT, LCO and 2MASS systems.
The 2MASS-MKO data scatter by 0.05 mag for redder stars: 2MASS-J includes H2O
features in dwarfs and MKO-K includes CO features in giants. Transformations
derived for stars whose spectra contain only weak features cannot give accurate
transformations for objects with strong absorption features within a filter
bandpasses. We find evidence of systematic effects at the 0.02 mag level in the
photometry of stars with J<11 and H,K<10.5. This is due to an underestimate of
the linearity correction for stars observed with the shortest exposure times;
very accurate photometry of stars approaching the saturation limits of infrared
detectors which are operated in double-read mode is difficult to obtain. Four
stars in the sample, GSPC S705-D, FS 116 (B216-b7), FS 144 (Ser-EC84) and FS 32
(Feige 108), may be variable. 84 stars in the sample have 11< J< 15 and
10.5<H,K<15, are not suspected to be variable, and have magnitudes with an
estimated error <0.027 mag; 79 of these have an error of <0.020 mag. These
represent the first published high-accuracy JHK stellar photometry in the MKO
photometric system; we recommend these objects be employed as primary standards
for that system [abridged].Comment: Accepted for publication in MNRAS, 14 pages, 5 Figure
Two-electron atoms, ions and molecules
The quantum mechanics of two-electron systems is reviewed, starting with the
ground state of the helium atom and helium-like ions, with central charge . For Z=1, demonstrating the stability of the negative hydrogen ion, H,
cannot be achieved using a mere product of individual electron wave functions,
and requires instead an explicit account for the anticorrelation among the two
electrons. The wave function proposed by Chandrasekhar is revisited, where the
permutation symmetry is first broken and then restored by a counter-term. More
delicate problems can be studied using the same strategy: the stability of
hydrogen-like ions for any value of the proton-to-electron mass
ratio ; the energy of the lowest spin-triplet state of helium and
helium-like ions; the stability of the doubly-excited hydrogen ion with
unnatural parity. The positronium molecule , which has been
predicted years ago and discovered recently, can also be shown to be stable
against spontaneous dissociation, though the calculation is a little more
involved. Emphasis is put on symmetry breaking which can either spoil or
improve the stability of systems.Comment: 16 pages, 2 figure
A Deep XMM-Newton Survey of M33: Point Source Catalog, Source Detection and Characterization of Overlapping Fields
We have obtained a deep 8-field XMM-Newton mosaic of M33 covering the galaxy
out to the D isophote and beyond to a limiting 0.2--4.5 keV unabsorbed
flux of 510 erg cm s (L410
erg s at the distance of M33). These data allow complete coverage of the
galaxy with high sensitivity to soft sources such as diffuse hot gas and
supernova remnants. Here we describe the methods we used to identify and
characterize 1296 point sources in the 8 fields. We compare our resulting
source catalog to the literature, note variable sources, construct hardness
ratios, classify soft sources, analyze the source density profile, and measure
the X-ray luminosity function. As a result of the large effective area of
XMM-Newton below 1 keV, the survey contains many new soft X-ray sources. The
radial source density profile and X-ray luminosity function for the sources
suggests that only 15% of the 391 bright sources with
L3.610 erg s are likely to be associated with M33,
and more than a third of these are known supernova remnants. The log(N)--log(S)
distribution, when corrected for background contamination, is a relatively flat
power-law with a differential index of 1.5, which suggests many of the other
M33 sources may be high-mass X-ray binaries. Finally, we note the discovery of
an interesting new transient X-ray source, which we are unable to classify.Comment: 26 pages, 6 tables, 13 figures, accepted for publication in ApJ
Evolution of trace gases and particles emitted by a chaparral fire in California
Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 hectare prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured physical and chemical changes that occurred in the isolated downwind plume in the first ~4 h after emission. The measurements were carried out onboard a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR), aerosol mass spectrometer (AMS), single particle soot photometer (SP2), nephelometer, LiCor CO_2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO_2; CO; NO_x; NH_3; non-methane organic compounds; organic aerosol (OA); inorganic aerosol (nitrate, ammonium, sulfate, and chloride); aerosol light scattering; refractory black carbon (rBC); and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O_3 to excess CO in the plume (ΔO_3/ΔCO) increased from −5.13 (±1.13) × 10^(−3) to 10.2 (±2.16) × 10^(−2) in ~4.5 h following smoke emission. Excess acetic and formic acid (normalized to excess CO) increased by factors of 1.73 ± 0.43 and 7.34 ± 3.03 (respectively) over the same time since emission. Based on the rapid decay of C_2H_4 we infer an in-plume average OH concentration of 5.27 (±0.97) × 10^6 molec cm^(−3), consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased over the course of 4 h. The observed ammonium increase was a factor of 3.90 ± 2.93 in about 4 h, but accounted for just ~36% of the gaseous ammonia lost on a molar basis. Some of the gas phase NH_3 loss may have been due to condensation on, or formation of, particles below the AMS detection range. NO_x was converted to PAN and particle nitrate with PAN production being about two times greater than production of observable nitrate in the first ~4 h following emission. The excess aerosol light scattering in the plume (normalized to excess CO_2) increased by a factor of 2.50 ± 0.74 over 4 h. The increase in light scattering was similar to that observed in an earlier study of a biomass burning plume in Mexico where significant secondary formation of OA closely tracked the increase in scattering. In the California plume, however, ΔOA/ΔCO_2 decreased sharply for the first hour and then increased slowly with a net decrease of ~20% over 4 h. The fraction of thickly coated rBC particles increased up to ~85% over the 4 h aging period. Decreasing OA accompanied by increased scattering/particle coating in initial aging may be due to a combination of particle coagulation and evaporation processes. Recondensation of species initially evaporated from the particles may have contributed to the subsequent slow rise in OA. We compare our results to observations from other plume aging studies and suggest that differences in environmental factors such as smoke concentration, oxidant concentration, actinic flux, and RH contribute significantly to the variation in plume evolution observations
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