2,514 research outputs found
Vertex-Coloring with Star-Defects
Defective coloring is a variant of traditional vertex-coloring, according to
which adjacent vertices are allowed to have the same color, as long as the
monochromatic components induced by the corresponding edges have a certain
structure. Due to its important applications, as for example in the
bipartisation of graphs, this type of coloring has been extensively studied,
mainly with respect to the size, degree, and acyclicity of the monochromatic
components.
In this paper we focus on defective colorings in which the monochromatic
components are acyclic and have small diameter, namely, they form stars. For
outerplanar graphs, we give a linear-time algorithm to decide if such a
defective coloring exists with two colors and, in the positive case, to
construct one. Also, we prove that an outerpath (i.e., an outerplanar graph
whose weak-dual is a path) always admits such a two-coloring. Finally, we
present NP-completeness results for non-planar and planar graphs of bounded
degree for the cases of two and three colors
Electrically Switchable Photonic Molecule Laser
We have studied the coherent intercavity coupling of the evanescent fields of
the whispering gallery modes of two terahertz quantum-cascade lasers
implemented as microdisk cavities. The electrically pumped single-mode
operating microcavities allow to electrically control the coherent mode
coupling for proximity distances of the cavities up to 30-40 \mu\m. The optical
emission of the strongest coupled photonic molecule can be perfectly switched
by the electrical modulation of only one of the coupled microdisks. The
threshold characteristics of the strongest coupled photonic molecule
demonstrates the linear dependence of the gain of a quantum-cascade laser on
the applied electric field.Comment: 4 pages, 4 figure
Modification of Drosophila cell surfaces by concanavalin A
The effect of Con A on the surface morphology of cultured cells of Drosophilia melanogaster growing on coverglasses was examined by scanning electron microscopy. With low lectin concentrations (5–10μg/ml) surface filaments disappeared and the cells flattened and spread against the glass surface. Cytoplasmic fusion bridges were observed in areas where cells made contact. Concentrations of Con A ranging between 50–500 μg/ml caused cell shrinkage and surface distortions without cell flattening and filament loss. These morphologic effects were not apparent if Con A binding sites were blocked by preincubation with α-methyl-D-mannopyranoside before application to the cell cultures. However, once the Con A-mediated changes were in effect, the cells failed to show recovery when they were returned to growth medium and a majority of the cells on the coverglasses degenerated. Presumably the cells whose morphology appears unaffected by Con A treatment are the survivors that repopulate cultures returned to growth medium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47670/1/441_2004_Article_BF00220663.pd
Crack-Like Processes Governing the Onset of Frictional Slip
We perform real-time measurements of the net contact area between two blocks
of like material at the onset of frictional slip. We show that the process of
interface detachment, which immediately precedes the inception of frictional
sliding, is governed by three different types of detachment fronts. These
crack-like detachment fronts differ by both their propagation velocities and by
the amount of net contact surface reduction caused by their passage. The most
rapid fronts propagate at intersonic velocities but generate a negligible
reduction in contact area across the interface. Sub-Rayleigh fronts are
crack-like modes which propagate at velocities up to the Rayleigh wave speed,
VR, and give rise to an approximate 10% reduction in net contact area. The most
efficient contact area reduction (~20%) is precipitated by the passage of slow
detachment fronts. These fronts propagate at anomalously slow velocities, which
are over an order of magnitude lower than VR yet orders of magnitude higher
than other characteristic velocity scales such as either slip or loading
velocities. Slow fronts are generated, in conjunction with intersonic fronts,
by the sudden arrest of sub-Rayleigh fronts. No overall sliding of the
interface occurs until either of the slower two fronts traverses the entire
interface, and motion at the leading edge of the interface is initiated. Slip
at the trailing edge of the interface accompanies the motion of both the slow
and sub-Rayleigh fronts. We might expect these modes to be important in both
fault nucleation and earthquake dynamics.Comment: 19 page, 5 figures, to appear in International Journal of Fractur
A UK survey of current ENT practice in the assessment of nasal patency
Nasal obstruction is a common ENT complaint; however, decisions on its management are challenging, with high rates of dissatisfaction following surgery. This study investigated the practice of UK clinicians in the evaluation of nasal patency.
Seventy-eight UK-based rhinologists were surveyed at the 2015 British Academic Conference in Otolaryngology.
Clinical history and examination are almost universally used to evaluate nasal blockage. The most commonly used test was the nasal misting pattern (73 per cent), followed by peak nasal inspiratory flow (19 per cent). The Sino-Nasal Outcome Test 22 or 23 was utilised by 29 per cent of respondents. Sixty-three per cent of respondents reported that a lack of equipment was the principle reason for not using objective measures, followed by time constraints and a lack of correlation with symptom scores.
British clinicians rely on clinical skills to evaluate nasal blockage. There is a desire for a simple, non-invasive device that objectively measures airflow for nasal breathing during physiological resting and correlates with subjective symptom scores
Spatially resolved mid-infrared observations of the triple system T Tauri
To enhance our knowledge of the characteristics and distribution of the
circumstellar dust associated with the individual components of the young
hierarchical triple system T Tau, observations in the N-band with MIDI at the
VLTI were performed. Our study is based on both the interferometric and the
spectrophotometric measurements and is supplemented by new visual and infrared
photometry. Also, the phases were investigated to determine the dominating
mid-infrared source in the close southern binary. The data were fit with the
help of a sophisticated physical disc model. This model utilises the radiative
transfer code MC3D that is based on the Monte-Carlo method. Extended
mid-infrared emission is found around all three components of the system.
Simultaneous fits to the photometric and interferometric data confirm the
picture of an almost face-on circumstellar disc around T Tau N. Towards this
star, the silicate band is seen in emission. This emission feature is used to
model the dust content of the circumstellar disc. Clear signs of dust
processing are found. Towards T Tau S, the silicate band is seen in absorption.
This absorption is strongly pronounced towards the infrared companion T Tau Sa
as can be seen from the first individual N-band spectra for the two southern
components. Our fits support the previous suggestion that an almost edge-on
disc is present around T Tau Sa. This disc is thus misaligned with respect to
the circumstellar disc around T Tau N. The interferometric data indicate that
the disc around T Tau Sa is oriented in the north-south direction, which
favours this source as launching site for the east-western jet. We further
determine from the interferometric data the relative positions of the
components of the southern binary.Comment: 24 pages, 19 figures, accepted for publication in A&
Trajectories of self-rated health in people with diabetes: Associations with functioning in a prospective community sample
© 2013 Schmitz et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Self-rated health (SRH) is a single-item measure that is one of the most widely used measures of general health in population health research. Relatively little is known about changes and the trajectories of SRH in people with chronic medical conditions. The aims of the present study were to identify and describe longitudinal trajectories of self-rated health (SRH) status in people with diabetes. Methods: A prospective community study was carried out between 2008 and 2011. SRH was assessed at baseline and yearly at follow-ups (n=1288). Analysis was carried out through trajectory modeling. The trajectory groups were subsequently compared at 4 years follow-up with respect to functioning. Results: Four distinct trajectories of SRH were identified: 1) 72.2% of the participants were assigned to a persistently good SRH trajectory; 2) 10.1% were assigned to a persistently poor SRH trajectory; 3) mean SRH scores changed from good to poor for one group (7.3%); while 4) mean SRH scores changed from poor to medium/good for another group (10.4%). Those with a persistently poor perception of health status were at higher risk for poor functioning at 4 years follow-up than those whose SRH scores decreased from good to poor. Conclusions: SRH is an important predictor for poor functioning in diabetes, but the trajectory of SRH seems to be even more important. Health professionals should pay attention to not only SRH per se, but also changes in SRH over time.This work was supported by Operating Grant MOP-84574 from the Canadian Institutes of Health Research (CIHR). GG was supported by a doctoral fellowship from the CIHR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Immunostimulation and Immunoinhibition of Premalignant Lesions
BACKGROUND: The immune reaction may be either stimulatory or inhibitory to tumor growth, depending upon the local ratio of immune reactants to tumor cells. HYPOTHESIS: A tumor-stimulatory immune response may be essential for survival of a neoplasm in vivo and for the biological progression from a premalignant lesion to a malignancy. Neither a positive nor a negative correlation between the magnitude of an immune-cell infiltrate and a cancer's prognosis can reveal whether the infiltrate was stimulating or inhibiting to the tumor's growth unless the position on the nonlinear curve that relates tumor growth to the magnitude of the immune reaction is known. DISCUSSION: This hypothesis is discussed in relation to the development of human malignant melanomas and colorectal cancers
Quantum Superposition States of Bose-Einstein Condensates
We propose a scheme to create a macroscopic ``Sch\"odinger cat'' state formed
by two interacting Bose condensates. In analogy with quantum optics, where the
control and engineering of quantum states can be maintained to a large extend,
we consider the present scheme to be an example of quantum atom optics at work.Comment: 24 pages, 6 figure
Developments in the Photonic Theory of Fluorescence
Conventional fluorescence commonly arises when excited molecules relax to their ground electronic state, and most of the surplus energy dissipates in the form of photon emission. The consolidation and full development of theory based on this concept has paved the way for the discovery of several mechanistic variants that can come into play with the involvement of laser input – most notably the phenomenon of multiphoton-induced fluorescence. However, other effects can become apparent when off-resonant laser input is applied during the lifetime of the initial excited state. Examples include a recently identified scheme for laser-controlled fluorescence. Other systems of interest are those in which fluorescence is emitted from a set of two or more coupled nanoemitters. This chapter develops a quantum theoretical outlook to identify and describe these processes, leading to a discussion of potential applications ranging from all-optical switching to the generation of optical vortices
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