9,617 research outputs found
On the mechanism of action of the cytostatic drug anguidine and of the immunosuppressive agent ovalicin, two sesquiterpenes from fungi
Transient behavior of surface plasmon polaritons scattered at a subwavelength groove
We present a numerical study and analytical model of the optical near-field
diffracted in the vicinity of subwavelength grooves milled in silver surfaces.
The Green's tensor approach permits computation of the phase and amplitude
dependence of the diffracted wave as a function of the groove geometry. It is
shown that the field diffracted along the interface by the groove is equivalent
to replacing the groove by an oscillating dipolar line source. An analytic
expression is derived from the Green's function formalism, that reproduces well
the asymptotic surface plasmon polariton (SPP) wave as well as the transient
surface wave in the near-zone close to the groove. The agreement between this
model and the full simulation is very good, showing that the transient
"near-zone" regime does not depend on the precise shape of the groove. Finally,
it is shown that a composite diffractive evanescent wave model that includes
the asymptotic SPP can describe the wavelength evolution in this transient
near-zone. Such a semi-analytical model may be useful for the design and
optimization of more elaborate photonic circuits whose behavior in large part
will be controlled by surface waves.Comment: 12 pages, 10 figure
The Bose-Einstein correlation function from a Quantum Field Theory point of view
We show that a recently proposed derivation of Bose-Einstein correlations
(BEC) by means of a specific version of thermal Quantum Field Theory (QFT),
supplemented by operator-field evolution of the Langevin type, allows for a
deeper understanding of the possible coherent behaviour of the emitting source
and a clear identification of the origin of the observed shape of the BEC
function . Previous conjectures in this matter obtained by other
approaches are confirmed and have received complementary explanation.Comment: Some misprints corrected. To be publishe in Phys. Rev.
Second order equation of motion for electromagnetic radiation back-reaction
We take the viewpoint that the physically acceptable solutions of the
Lorentz--Dirac equation for radiation back-reaction are actually determined by
a second order equation of motion, the self-force being given as a function of
spacetime location and velocity. We propose three different methods to obtain
this self-force function. For two example systems, we determine the second
order equation of motion exactly in the nonrelativistic regime via each of
these three methods, the three methods leading to the same result. We reveal
that, for both systems considered, back-reaction induces a damping proportional
to velocity and, in addition, it decreases the effect of the external force.Comment: 13 page
Incorporation of an Interprofessional Palliative Care-Ethics Experience Into a Required Critical Care Acting Internship.
Introduction: The literature documents inadequate palliative medicine training in undergraduate and graduate medical education. As the population lives longer, many people will experience multiple chronic illnesses and the associated symptom burden. All physicians involved in clinical care of patients need to be equipped with the knowledge, attitudes, and skills necessary to provide palliative care, yet most physicians do not feel adequately prepared. We designed a curriculum to provide a meaningful palliative care-ethics (PCE) clinical experience to prepare senior medical students for future practice regardless of specialty choice.
Methods: The Zucker School of Medicine at Hofstra/Northwell integrated a PCE experience into the required 4-week acting internship in critical care (AICC). Students met weekly with an interprofessional faculty member and presented clinical cases focusing on communication and/or bioethical challenges. Faculty facilitators ensured that the presentations integrated discussion of communication skills. During the final session, students shared written reflections. Students were invited to complete a satisfaction survey postrotation and 1 year after graduation.
Results: The curriculum was evaluated positively by the graduating classes of 2015 (
Discussion: It is feasible to incorporate an interprofessional PCE experience into a required AICC. Students indicated a better understanding of palliative care and, at 1 year postgraduation, reported feeling comfortable caring for patients with serious illness
Enhancement and evaluation of Skylab photography for potential land use inventories, part 1
The author has identified the following significant results. Three sites were evaluated for land use inventory: Finger Lakes - Tompkins County, Lower Hudson Valley - Newburgh, and Suffolk County - Long Island. Special photo enhancement processes were developed to standardize the density range and contrast among S190A negatives. Enhanced black and white enlargements were converted to color by contact printing onto diazo film. A color prediction model related the density values on each spectral band for each category of land use to the spectral properties of the various diazo dyes. The S190A multispectral system proved to be almost as effective as the S190B high resolution camera for inventorying land use. Aggregate error for Level 1 averaged about 12% while Level 2 aggregate error averaged about 25%. The S190A system proved to be much superior to LANDSAT in inventorying land use, primarily because of increased resolution
Frege on the Generality of Logical Laws
Frege claims that the laws of logic are characterized by their âgenerality,â but it is hard to see how this could identify a special feature of those laws. I argue that we must understand this talk of generality in normative terms, but that what Frege says provides a normative demarcation of the logical laws only once we connect it with his thinking about truth and science. He means to be identifying the laws of logic as those that appear in every one of the scientific systems whose construction is the ultimate aim of science, and in which all truths have a place. Though an account of logic in terms of scientific systems might seem hopelessly antiquated, I argue that it is not: a basically Fregean account of the nature of logic still looks quite promising
AEGIS: Extinction and Star Formation Tracers from Line Emission
Strong nebular emission lines are a sensitive probe of star formation and
extinction in galaxies, and the [O II] line detects star forming populations
out to z>1. However, star formation rates from emission lines depend on
calibration of extinction and the [O II]/H-alpha line ratio, and separating
star formation from AGN emission. We use calibrated line luminosities from the
DEEP2 survey and Palomar K magnitudes to show that the behavior of emission
line ratios depends on galaxy magnitude and color. For galaxies on the blue
side of the color bimodality, the vast majority show emission signatures of
star formation, and there are strong correlations of extinction and [O
II]/H-alpha with restframe H magnitude. The conversion of [O II] to
extinction-corrected H-alpha and thus to star formation rate has a significant
slope with M_H, 0.23 dex/mag. Red galaxies with emission lines have a much
higher scatter in their line ratios, and more than half show AGN signatures. We
use 24 micron fluxes from Spitzer/MIPS to demonstrate the differing populations
probed by nebular emission and by mid-IR luminosity. Although extinction is
correlated with luminosity, 98% of IR-luminous galaxies at z~1 are still
detected in the [O II] line. Mid-IR detected galaxies are mostly bright and
intermediate color, while fainter, bluer galaxies with high [O II] luminosity
are rarely detected at 24 microns.Comment: 4 pages, 3 figures. Accepted for publication in ApJ Letters AEGIS
special editio
Deciphering nonfemtoscopic two-pion correlations in collisions with simple analytical models
A simple model of nonfemtoscopic particle correlations in proton-proton
collisions is proposed. The model takes into account correlations induced by
the conservation laws as well as correlations induced by minijets. It
reproduces well the two-pion nonfemtoscopic correlations of like-sign and
unlike-sign pions in proton-proton collision events at GeV
analyzed by the ALICE Collaboration. We also argue that similar nonfemtoscopic
correlations can appear in the hydrodynamic picture with event-by-event
fluctuating nonsymmetric initial conditions that are typically associated with
nonzero higher-order flow harmonics.Comment: 21 pages, 10 figures, misprints correcte
Analysis of the Relationship Between Diet and Exercise Beliefs and Actual Behaviors Among Breast Cancer Survivors in Northwest Ohio
Introduction: Studies have shown that a diet high in fruit and vegetable intake, as well as a routine including daily exercise or physical activity, can independently affect relapse rates and survivorship in breast cancer patients. Fruits and vegetables contain powerful anti-oxidant molecules, capable of preventing tumor formation and proliferation. Exercise can lower circulating levels of estrogen, the female hormone responsible for tumor proliferation in the estrogen-sensitive form of the disease. The most beneficial results have been shown in women who exercise and consume a diet rich in fruits and vegetables. We studied the attitudes towards and behaviors related to fruit and vegetable intake and exercise in a cohort of breast cancer survivors in northwest Ohio. Materials and Methods: Data were gathered from a survey sent out by the Northwest Ohio Branch of the Susan G. Komen For the Cure Foundation. We assessed and evaluated survivorsâ self-reported beliefs, attitudes, and behaviors regarding exercise and fruit and vegetable intake. Results: Nearly half of the survivors (46.5%) reported being unsure or in disagreement with the statement âEating at least 5 servings of fruits and/or vegetables per day will reduce the risk of breast cancer recurrence.â Only 46.8% of those in agreement with the previous statement actually report eating at least 5 fruits and/or vegetables per day. With respect to exercise, 32.9% reported being unsure or in disagreement with the statement âEngaging in regular physical activity will reduce the risk of breast cancer recurrence.â Only 68.5% of those in agreement with the previous statement report any physical activity in the past 30 days. Conclusions: Many breast cancer survivors do not appear to be aware of the benefits of diet and exercise. Further, a large proportion of those who are aware of the benefits do not adapt a healthy diet and exercise as part of their lifestyle. A majority of these survivors see a primary care physician, which we believe is the best venue to bridge this education gap. It is apparent by the pattern our data shows that more needs to be done to educate breast cancer survivors about the benefits of exercise and fruit and vegetable intake. Steps need to be taken to ensure that those who are educated also remain motivated to engage in a healthy lifestyle with the hopes of avoiding breast cancer recurrence
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