15,861 research outputs found
The diastereoselective Meth-Cohn epoxidation of camphor-derived vinyl sulfones
Some camphor-derived vinyl sulfones bearing oxygen functionality at the allylic position have been synthesized and their nucleophilic epoxidation reactions under Meth-Cohn conditions have been explored. The γ-oxygenated camphor-derived vinyl sulfones underwent mildly diastereoselective nucleophilic epoxidation reactions, affording the derived sulfonyloxiranes in up to 5.8:1 dr. The observed diastereoselectivities were sensitive to the reaction conditions employed. In contrast, no stereoselectivity was observed in the nucleophilic epoxidation of the corresponding γ-oxygenated isobornyl vinyl sulfone. A tentative mechanism has been proposed to explain the origins of the diastereoselectivit
Residual tumor cells that drive disease relapse after chemotherapy do not have enhanced tumor initiating capacity.
Although chemotherapy is used to treat most advanced solid tumors, recurrent disease is still the major cause of cancer-related mortality. Cancer stem cells (CSCs) have been the focus of intense research in recent years because they provide a possible explanation for disease relapse. However, the precise role of CSCs in recurrent disease remains poorly understood and surprisingly little attention has been focused on studying the cells responsible for re-initiating tumor growth within the original host after chemotherapy treatment. We utilized both xenograft and genetically engineered mouse models of non-small cell lung cancer (NSCLC) to characterize the residual tumor cells that survive chemotherapy treatment and go on to cause tumor regrowth, which we refer to as tumor re-initiating cells (TRICs). We set out to determine whether TRICs display characteristics of CSCs, and whether assays used to define CSCs also provide an accurate readout of a cell's ability to cause tumor recurrence. We did not find consistent enrichment of CSC marker positive cells or enhanced tumor initiating potential in TRICs. However, TRICs from all models do appear to be in EMT, a state that has been linked to chemoresistance in numerous types of cancer. Thus, the standard CSC assays may not accurately reflect a cell's ability to drive disease recurrence
Living with multiple losses: Insights from patients living with pressure injury
© 2017 Australian College of Nursing Ltd Background: Pressure injury is a common problem. Its prevention and treatment is predominantly focussed on views, perceptions and knowledge of healthcare staff rather than on patient experience, particularly those patients living in their own homes. Aim: This paper reports findings on patients experiences and perceptions of loss associated with PI. These findings are drawn from a larger study of pressure injury patients living and receiving care in the community. Methods: Qualitative interviews with 12 participants with pressure injury and five carers. Data was audio recorded and thematically analysed. The study is reported in accordance with the COREQ guidelines. Findings: Having a pressure injury negatively affected many aspects of life for our participants resulting in multiple losses. These losses included loss of mobility and independence, privacy and dignity, and social engagement and ability to engage in preferred activities. Discussion: Although the effects of a pressure injury may be similar for many people, the most important issues will differ from person-to-person thus treatment and prevention of pressure injury requires a multidisciplinary team having a holistic care approach. Some patients’ pressure injury will never heal and it is increasingly important to involve the patient to find out what matters most to them and how their wound is impacting on them, to jointly develop a holistic, person-centred plan. Conclusion: Policy and practice should recognise and reflect that patients living with a pressure injury at home have different challenges and needs to those in acute or long term care. Pragmatic solutions in the delivery of pressure injury care are needed to compliment the drive to move healthcare from the hospital-to-home
Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being
This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics
The nature and origins of the low surface brightness outskirts of massive, central galaxies in Subaru HSC
We explore the stellar mass density and colour profiles of 118 low redshift,
massive, central galaxies, selected to have assembled 90 percent of their
stellar mass 6 Gyr ago, finding evidence of the minor merger activity expected
to be the driver behind the size growth of quiescent galaxies. We use imaging
data in the bands from the Subaru Hyper Suprime-Cam survey and
perform SED fitting to construct spatially well-resolved radial profiles in
colour and stellar mass surface density. Our visual morphological
classification reveals that percent of our sample displays tidal
features, similar to previous studies, percent of the remaining
sample display a diffuse stellar halo and only percent display no
features, down to a limiting 28 mag
arcsec. We find good agreement between the stacked colour profiles of
our sample to those derived from previous studies and an expected smooth,
declining stellar mass surface density profile in the central regions (< 3
R). However, we also see a flattening of the profile ( M kpc) in the outskirts (up to 10
R), which is revealed by our method of specifically targeting
tidal/accretion features. We find similar levels of tidal features and
behaviour in the stellar mass surface density profiles in a younger comparison
sample, however a lack of diffuse haloes. We also apply stacking techniques,
similar to those in previous studies, finding such procedures wash out tidal
features and thereby produces smooth declining profiles. The stellar material
in the outskirts contributes on average M or a few
percent of the total stellar mass and has similar colours to SDSS satellites of
similar stellar mass.Comment: 14 pages, 9 figures, 1 tabl
Attenuation of acoustic waves in glacial ice and salt domes
Two classes of natural solid media (glacial ice and salt domes) are under
consideration as media in which to deploy instruments for detection of
neutrinos with energy >1e18 eV. Though insensitive to 1e11 to 1e16 eV neutrinos
for which observatories (e.g., AMANDA and IceCube) that utilize optical
Cherenkov radiation detectors are designed, radio and acoustic methods are
suited for searches for the very low fluxes of neutrinos with energies >1017
eV. This is because, due to the very long attenuation lengths of radio and
acoustic waves in ice and salt, detection modules can be spaced very far apart.
In this paper, I calculate the absorption and scattering coefficients as a
function of frequency and grain size for acoustic waves in glacial ice and salt
domes and show that experimental measurements on laboratory samples and in
glacial ice and salt domes are consistent with theory. For South Pole ice with
grain size 0.2 cm at -51 degrees C, scattering lengths are calculated to be
2000 km and 25 km at 10 kHz and 30 kHz, respectively, and the absorption length
is calculated to be 9 km at frequencies above 100 Hz. For NaCl (rock salt) with
grain size 0.75 cm, scattering lengths are calculated to be 120 km and 1.4 km
at 10 kHz and 30 kHz, and absorption lengths are calculated to be 30,000 km and
3300 km at 10 kHz and 30 kHz. Existing measurements are consistent with theory.
For ice, absorption is the limiting factor; for salt, scattering is the
limiting factor.Comment: 16 pages, 7 figures, submitted to Journal of Geophysical Research -
Solid Eart
Gravity and the Quantum Vacuum Inertia Hypothesis
In previous work it has been shown that the electromagnetic quantum vacuum,
or electromagnetic zero-point field, makes a contribution to the inertial
reaction force on an accelerated object. We show that the result for inertial
mass can be extended to passive gravitational mass. As a consequence the weak
equivalence principle, which equates inertial to passive gravitational mass,
appears to be explainable. This in turn leads to a straightforward derivation
of the classical Newtonian gravitational force. We call the inertia and
gravitation connection with the vacuum fields the quantum vacuum inertia
hypothesis. To date only the electromagnetic field has been considered. It
remains to extend the hypothesis to the effects of the vacuum fields of the
other interactions. We propose an idealized experiment involving a cavity
resonator which, in principle, would test the hypothesis for the simple case in
which only electromagnetic interactions are involved. This test also suggests a
basis for the free parameter which we have previously defined to
parametrize the interaction between charge and the electromagnetic zero-point
field contributing to the inertial mass of a particle or object.Comment: 18 pages, no figures. Annalen der Physik, 2005, in press. New version
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