80 research outputs found
High ions towards white dwarfs: circumstellar line shifts and stellar temperature
Based on a compilation of OVI, CIV, SiIV and NV data from IUE, FUSE, GHRS,
STIS, and COS, we derive an anti- correlation between the stellar temperature
and the high ion velocity shift w.r.t. to the photosphere, with positive (resp.
negative) velocity shifts for the cooler (resp. hotter) white dwarfs. This
trend probably reflects more than a single process, however such a dependence
on the WD's temperature again favors a CS origin for a very large fraction of
those ion absorptions, previously observed with IUE, HST-STIS, HST-GHRS, FUSE,
and now COS, selecting objects for which absorption line radial velocities,
stellar effective temperature and photospheric velocity can be found in the
literature. Interestingly, and gas in near-equilibrium in the star vicinity. It
is also probably significant that the temperature that corresponds to a null
radial velocity, i.e. \simeq 50,000K, also corresponds to the threshold below
which there is a dichotomy between pure or heavy elements atmospheres as well
as some temperature estimates for and a form of balance between radiation
pressure and gravitation. This is consistent with ubiquitous evaporation of
orbiting dusty material. Together with the fact that the fraction of stars with
(red-or blue-) shifted lines and the fraction of stars known to possess heavy
species in their atmosphere are of the same order, such a velocity-temperature
relationship is consistent with quasi-continuous evaporation of orbiting CS
dusty material, followed by accretion and settling down in the photosphere. In
view of these results, ion measurements close to the photospheric or the IS
velocity should be interpreted with caution, especially for stars at
intermediate temperatures. While tracing CS gas, they may be erroneously
attributed to photospheric material or to the ISM, explaining the difficulty of
finding a coherent pattern of the high ions in the local IS 3D distribution.Comment: Accepted by A&A. Body of paper identical to v1. This submission has a
more appropriate truncation of the original abstrac
The management of the painful bipartite patella: a systematic review
Purpose: This study aimed to identify the most effective method for the treatment of the symptomatic bipartite patella. Methods: A systematic review of the literature was completed, and all studies assessing the management of a bipartite patella were included. Owing to the paucity of randomised controlled trials, a narrative review of 22 studies was completed. A range of treatments were assessed: conservative measures, open and arthroscopic fixation or excision and soft tissue release and excision. Results: All of the methods provided results ranging from good to excellent, with acceptable complication rates. Conclusions: This is a poorly answered treatment question. No firm guidance can be given as to the most appropriate method of treating the symptomatic bipartite patella. This study suggests that there are a number of effective treatments with acceptable complication rates and it may be that treatments that conserve the patella are more appropriate for larger fragments
Thermal Instability & the Feedback Regulation of Hot Halos in Clusters, Groups, and Galaxies
Observations of clusters and groups imply that such halos are roughly in
global thermal equilibrium, with heating balancing cooling when averaged over
sufficiently long time- and length-scales; the ICM is, however, very likely to
be locally thermally unstable. Using simple observationally-motivated heating
prescriptions, we show that local thermal instability (TI) can produce a
multi-phase medium---with ~ 10000 K cold filaments condensing out of the hot
ICM---only when the ratio of the TI timescale in the hot plasma (t_{TI}) to the
free-fall timescale (t_{ff}) satisfies t_{TI}/t_{ff} <~ 10. This criterion
quantitatively explains why cold gas and star formation are preferentially
observed in low-entropy clusters and groups. In addition, the interplay among
heating, cooling, and TI reduces the net cooling rate and the mass accretion
rate at small radii by factors of ~ 100 relative to cooling-flow models. This
dramatic reduction is in line with observations. The feedback efficiency
required to prevent a cooling-flow is ~ 0.001 for clusters and decreases for
lower mass halos; supernova heating may be energetically sufficient to balance
cooling in galactic halos. We further argue that the ICM self-adjusts so that
t_{TI}/t_{ff} >~ 10 at all radii. When this criterion is not satisfied, cold
filaments condense out of the hot phase and reduce the density of the ICM.
These cold filaments can power the black hole and/or stellar feedback required
for global thermal balance, which drives t_{TI}/t_{ff} >~ 10. In comparison to
clusters, groups have central cores with lower densities and larger radii. This
can account for the deviations from self-similarity in the X-ray
luminosity-temperature (L_X-T_X) relation. The high-velocity clouds observed in
the Galactic halo can also be due to local TI producing multi-phase gas close
to the virial radius.Comment: 26 pages, 18 figures; abstract abridged; to be submitted to MNRA
20-Year Risks of Breast-Cancer Recurrence after Stopping Endocrine Therapy at 5 Years
The administration of endocrine therapy for 5 years substantially reduces recurrence rates during and after treatment in women with early-stage, estrogen-receptor (ER)-positive breast cancer. Extending such therapy beyond 5 years offers further protection but has additional side effects. Obtaining data on the absolute risk of subsequent distant recurrence if therapy stops at 5 years could help determine whether to extend treatment
Moose and snowshoe hare competition and a mechanistic explanation from foraging theory
Moose ( Alces alces ) and snowshoe hare ( Lepus americanus ) appear to compete with each other. This was determined using the “natural experiments” of populations found in sympatry and allopatry on islands at Isle Royale National Park, Michigan, and manipulated exclosures. The population densities from these areas are fit to a series of competition models based upon different competitive mechanisms (Schoener 1974a), using non-linear regression techniques. A model of competition for food where the food can be separated into exclusively used and shared categories is found to predict observed densities of moose and hare best. Finally, the competition model's parameters (fraction of food shared and competition coefficients) are shown to agree with values predicted independently from a foraging model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47750/1/442_2004_Article_BF00396753.pd
Long-term outcomes for neoadjuvant versus adjuvant chemotherapy in early breast cancer: meta-analysis of individual patient data from ten randomised trials
Background
Neoadjuvant chemotherapy (NACT) for early breast cancer can make breast-conserving surgery more feasible and might be more likely to eradicate micrometastatic disease than might the same chemotherapy given after surgery. We investigated the long-term benefits and risks of NACT and the influence of tumour characteristics on outcome with a collaborative meta-analysis of individual patient data from relevant randomised trials.
Methods
We obtained information about prerandomisation tumour characteristics, clinical tumour response, surgery, recurrence, and mortality for 4756 women in ten randomised trials in early breast cancer that began before 2005 and compared NACT with the same chemotherapy given postoperatively. Primary outcomes were tumour response, extent of local therapy, local and distant recurrence, breast cancer death, and overall mortality. Analyses by intention-to-treat used standard regression (for response and frequency of breast-conserving therapy) and log-rank methods (for recurrence and mortality).
Findings
Patients entered the trials from 1983 to 2002 and median follow-up was 9 years (IQR 5–14), with the last follow-up in 2013. Most chemotherapy was anthracycline based (3838 [81%] of 4756 women). More than two thirds (1349 [69%] of 1947) of women allocated NACT had a complete or partial clinical response. Patients allocated NACT had an increased frequency of breast-conserving therapy (1504 [65%] of 2320 treated with NACT vs 1135 [49%] of 2318 treated with adjuvant chemotherapy). NACT was associated with more frequent local recurrence than was adjuvant chemotherapy: the 15 year local recurrence was 21·4% for NACT versus 15·9% for adjuvant chemotherapy (5·5% increase [95% CI 2·4–8·6]; rate ratio 1·37 [95% CI 1·17–1·61]; p=0·0001). No significant difference between NACT and adjuvant chemotherapy was noted for distant recurrence (15 year risk 38·2% for NACT vs 38·0% for adjuvant chemotherapy; rate ratio 1·02 [95% CI 0·92–1·14]; p=0·66), breast cancer mortality (34·4% vs 33·7%; 1·06 [0·95–1·18]; p=0·31), or death from any cause (40·9% vs 41·2%; 1·04 [0·94–1·15]; p=0·45).
Interpretation
Tumours downsized by NACT might have higher local recurrence after breast-conserving therapy than might tumours of the same dimensions in women who have not received NACT. Strategies to mitigate the increased local recurrence after breast-conserving therapy in tumours downsized by NACT should be considered—eg, careful tumour localisation, detailed pathological assessment, and appropriate radiotherapy
Verkannte Verse (Zu einer thessalischen Inschrift)
Peek Werner. Verkannte Verse (Zu einer thessalischen Inschrift). In: Bulletin de correspondance hellénique. Volume 93, livraison 2, 1969. pp. 838-840
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