1,595 research outputs found
STUDIES OF PHYSIOLOGICALLY ACTIVE ARTHROPOD SECRETIONS: X. SEX PHEROMONE OF THE EASTERN SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)
The sex pheromone of the female eastern spruce budworm was identified as trans-11-tetradecenal by a combination of electroantennogram techniques, laboratory bioassays, and chemical analysis. Subsequent field trapping showed that this compound is a potent attractant for both male Choristoneura fumiferana (Clem.) and C. occidentalis Free, thus supporting its identification as a sex pheromone of the eastern spruce budworm and suggesting that it is also a major component in the pheromone system of C. occidentali
Theory of adsorbate induced surface reconstruction on W(100)
We report results of a theoretical study on an adsorbate induced surface
reconstruction. Hydrogen adsorption on a W(100) surface causes a switching
transition in the symmetry of the displacements of the W atoms within the
ordered c(2x2) phase. This transition is modeled by an effective Hamiltonian,
where the hydrogen degrees of freedom are integrated out. Based on extensive
Monte Carlo renormalisation group calculations we show that the switching
transition is of second order at high temperatures and of first order at low
temperatures. This behavior is qualitatively explained in terms of an XY model
where there is an interplay between four and eight fold anisotropy fields. We
also compare the calculated phase diagrams with a simple mean field theory.Comment: CSC Preprint, 31 pages (plain TeX file, no figures
Attractancy of Racemic Disparlure and Certain Analogues to Male Gypsy Moths and the Effect of Trap Placement
Traps hung on small trees of 3-8 cm diam and baited with racemic epoxides, hydrocarbons and other analogues related to racemic cis-7,8-epoxy-2-methyloctadecane (disparlure) resulted in male Lymantria dispar L. (gypsy moth) catches statistically indistinguishable from those of unbaited traps. Only (±)-disparlure yielded trap catches statistically above the level of unbaited traps. However, trap placement on trees of ca. 0.5 m diam produced appreciable trap catches, even in unbaited trap
The impact of organ motion and the appliance of mitigation strategies on the effectiveness of hypoxia-guided proton therapy for non-small cell lung cancer.
BACKGROUND AND PURPOSE
To investigate the impact of organ motion on hypoxia-guided proton therapy treatments for non-small cell lung cancer (NSCLC) patients.
MATERIALS AND METHODS
Hypoxia PET and 4D imaging data of six NSCLC patients were used to simulate hypoxia-guided proton therapy with different motion mitigation strategies including rescanning, breath-hold, respiratory gating and tumour tracking. Motion-induced dose degradation was estimated for treatment plans with dose painting of hypoxic tumour sub-volumes at escalated dose levels. Tumour control probability (TCP) and dosimetry indices were assessed to weigh the clinical benefit of dose escalation and motion mitigation. In addition, the difference in normal tissue complication probability (NTCP) between escalated proton and photon VMAT treatments have been assessed.
RESULTS
Motion-induced dose degradation was found for target coverage (CTV V95% up to -4%) and quality of the dose-escalation-by-contour (QRMS up to 6%) as a function of motion amplitude and amount of dose escalation. The TCP benefit coming from dose escalation (+4-13%) outweighs the motion-induced losses (<2%). Significant average NTCP reductions of dose-escalated proton plans were found for lungs (-14%), oesophagus (-10%) and heart (-16%) compared to conventional VMAT plans. The best plan dosimetry was obtained with breath hold and respiratory gating with rescanning.
CONCLUSION
NSCLC affected by hypoxia appears to be a prime target for proton therapy which, by dose-escalation, allows to mitigate hypoxia-induced radio-resistance despite the sensitivity to organ motion. Furthermore, substantial reduction in normal tissue toxicity can be expected compared to conventional VMAT. Accessibility and standardization of hypoxia imaging and clinical trials are necessary to confirm these findings in a clinical setting
Supersymmetric version of a Gaussian irrotational compressible fluid flow
The Lie point symmetries and corresponding invariant solutions are obtained
for a Gaussian, irrotational, compressible fluid flow. A supersymmetric
extension of this model is then formulated through the use of a superspace and
superfield formalism. The Lie superalgebra of this extended model is determined
and a classification of its subalgebras is performed. The method of symmetry
reduction is systematically applied in order to derive special classes of
invariant solutions of the supersymmetric model. Several new types of
algebraic, hyperbolic, multi-solitonic and doubly periodic solutions are
obtained in explicit form.Comment: Expanded introduction and added new section on classical Gaussian
fluid flow. Included several additional reference
SDSS J124058.03-015919.2: A new AM CVn star with a 37-minute orbital period
We present high time resolution VLT spectroscopy of SDSS J124058.03-015919.2,
a new helium-transferring binary star identified in the Sloan Digital Sky
Survey. We measure an orbital period of 37.355+/-0.002 minutes, confirming the
AM CVn nature of the system. From the velocity amplitudes of the accretor and
the accretion stream--disc impact, we derive a mass ratio q=0.039+/-0.010. Our
spectral coverage extends from 3700A--9500A and shows the presence of helium,
nitrogen, silicon and iron in the accretion disc, plus the redshifted,
low-velocity "central spikes" in the helium lines, known from the low-state AM
CVn stars GP Com and CE 315. Doppler tomography of the helium and silicon
emission lines reveals an unusual pattern of two bright emission sites in the
tomograms, instead of the usual one emission site identified with the impact of
the mass stream into the accretion disc. One of the two is preferred as the
conventional stream--disc impact point in velocity space, at the 3-sigma
confidence level. We speculate briefly on the origin of the second.Comment: Accepted for publication in MNRA
A search for the hidden population of AM CVn binaries in the Sloan Digital Sky Survey
We present the latest results from a spectroscopic survey designed to uncover the hidden population of AM Canum Venaticorum (AM CVn) binaries in the photometric data base of the Sloan Digital Sky Survey (SDSS). We selected ∼2000 candidates based on their photometric colours, a relatively small sample which is expected to contain the majority of all AM CVn binaries in the SDSS (expected to be ∼50).
We present two new candidate AM CVn binaries discovered using this strategy: SDSS J104325.08+563258.1 and SDSS J173047.59+554518.5. We also present spectra of 29 new cataclysmic variables, 23 DQ white dwarfs and 21 DZ white dwarfs discovered in this survey.
The survey is now approximately 70 per cent complete, and the discovery of seven new AM CVn binaries indicates a lower space density than previously predicted. From the essentially complete g ≤ 19 sample, we derive an observed space density of (5 ± 3) × 10^(−7) pc^(−3); this is lower than previous estimates by a factor of 3.
The sample has been cross-matched with the GALEX All-Sky Imaging Survey data base, and with Data Release 9 of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS). The addition of UV photometry allows new colour cuts to be applied, reducing the size of our sample to ∼1100 objects. Optimizing our follow-up should allow us to uncover the remaining AM CVn binaries present in the SDSS, providing the larger homogeneous sample required to more reliably estimate their space density
Anemia in young children living in the Surinamese interior:The influence of age, nutritional status and ethnicity
Purpose: This study investigates the prevalence of anemia in young children living in the interior of Suriname and the influence of the associated factors age, nutritional status and ethnicity. Patients and methods: In this cross-sectional observational study, 606 children aged 1-5 years from three different regions of Suriname's interior were included, and hemoglobin levels and anthropometric measurements were collected. Logistic regression models were computed to examine independent associations between anemic and nonanemic groups and to measure the influence of age, nutritional status and ethnicity. Results: A total of 606 children were included, of whom 330 (55%) were aged 1-3 years and 276 were aged 4-5 years. The overall prevalence of anemia was 63%. Younger age was associated with anemia (odds ratio [OR]= 1.78; 95% confidence interval [CI]: 1.27-2.51). Anemia was less prevalent in Amerindian than in Maroon children (OR=0.51; 95% CI: 0.34-0.76). Hemoglobin level was not influenced by nutritional status nor by sex. Conclusion: The prevalence of anemia in children aged 1-5 years living in Suriname's interior is high (63%) compared to that in similar aged children in Latin America and the Caribbean (4-45%). Children aged 1-3 years were more affected than those aged 4-5 years as were Maroon children compared to Amerindian children. Nutritional status and sex were not of influence
Invariant vector fields and the prolongation method for supersymmetric quantum systems
The kinematical and dynamical symmetries of equations describing the time
evolution of quantum systems like the supersymmetric harmonic oscillator in one
space dimension and the interaction of a non-relativistic spin one-half
particle in a constant magnetic field are reviewed from the point of view of
the vector field prolongation method. Generators of supersymmetries are then
introduced so that we get Lie superalgebras of symmetries and supersymmetries.
This approach does not require the introduction of Grassmann valued
differential equations but a specific matrix realization and the concept of
dynamical symmetry. The Jaynes-Cummings model and supersymmetric
generalizations are then studied. We show how it is closely related to the
preceding models. Lie algebras of symmetries and supersymmetries are also
obtained.Comment: 37 pages, 7 table
Porto-sinusoidal vascular disorder and nephrotic-range proteinuria due to venous vasculitis in Behçet's disease
Behçet's disease (BD) is an autoinflammatory disease with multifactorial and polygenic etiology, potentially involving arteries and veins of any size resulting in variable vessel vasculitis. We report a case of an Iranian male who presented with porto-sinusoidal vascular disorder due to venous vasculitis as initial manifestation of BD. Despite immunosuppression, anticoagulation and venous recanalization, he subsequently developed severe nephrotic-range proteinuria mimicking a primary renal disease which was completely and immediately ameliorated by stenting of the vena cava. This demonstrates that the proteinuria was caused by increased intraglomerular pressure due to venous outflow obstruction as a consequence of venous vasculitis. To our knowledge, this is the first report of massive proteinuria caused by venous obstruction of the caval vein in the context of BD. Altogether, this case demonstrates the extensive spectrum of vascular disease in BD.</p
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