1,677 research outputs found
Optical Observations of the Binary Millisecond Pulsars J2145-0750 and J0034-0534
We report on optical observations of the low-mass binary millisecond pulsar
systems J0034-0534 and J2145-0750. A faint (I=23.5) object was found to be
coincident with the timing position of PSR J2145-0750. While a galaxy or
distant main-sequence star cannot be ruled out, its magnitude is consistent
with an ancient white dwarf, as expected from evolutionary models. For PSR
J0034-0534 no objects were detected to a limiting magnitude of R=25.0,
suggesting that the white dwarf in this system is cold. Using white dwarf
cooling models, the limit on the magnitude of the PSR J0034-0534 companion
suggests that at birth the pulsar in this system may have rotated with a period
as short as 0.6 ms. These observations provide further evidence that the
magnetic fields of millisecond pulsars do not decay on time scales shorter than
1 Gyr.Comment: 6 pages, uuencoded, gz -9 compressed postscript, accepted by ApJ
Relationship between emergency presentation, systemic inflammatory response, and cancer-specific survival in patients undergoing potentially curative surgery for colon cancer
Background
Emergency presentation is recognized to be associated with poorer cancer-specific survival following curative resection for colorectal cancer. The present study examined the hypothesis that an enhanced systemic inflammatory response, prior to surgery, might explain the impact of emergency presentation on survival.
Methods
In all, 188 patients undergoing potentially curative resection for colorectal cancer were studied. Of these, 55 (29%) presented as emergencies. The systemic inflammatory response was assessed using the Glasgow Prognostic Score (mGPS), which is the combination of an elevated C-reactive protein (>10 mg/L) and hypoalbuminemia (<35 g/L).
Results
In the emergency group, tumor stage was greater (P < 0.01), more patients received adjuvant therapy (P < 0.01) more patients had an elevated mGPS (P < 0.01), and more patients died of their disease (P < 0.05). The minimum follow-up was 12 months; the median follow-up of the survivors was 48 months. Emergency presentation was associated with poorer 3-year cancer-specific survival in those patients aged 65 to 74 years (P < 0.01), in both males and females (P < 0.05), in the deprived (P < 0.01), in patients with tumor-node-metastasis (TNM) stage II disease (P < 0.01), in those who received no adjuvant therapy (P < 0.01), and in the mGPS 0 and 1 groups (P < 0.05) groups. On multivariate survival analysis of patients undergoing potentially curative surgery for TNM stage II colon cancer, emergency presentation (P < 0.05) and mGPS (P < 0.05) were independently associated with cancer-specific survival.
Conclusions
These results suggest that emergency presentation and the presence of systemic inflammatory response prior to surgery are linked and account for poorer cancer-specific survival in patients undergoing potentially curative surgery for colon cancer. Both emergency presentation and an elevated mGPS should be taken into account when assessing the likely outcome of these patients
Direct Amidation of Esters via Ball Milling
The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent
Preoperative systemic inflammation predicts postoperative infectious complications in patients undergoing curative resection for colorectal cancer
The presence of systemic inflammation before surgery, as evidenced by the glasgow prognostic score (mGPS), predicts poor long-term survival in colorectal cancer. The aim was to examine the relationship between the preoperative mGPS and the development of postoperative complications in patients undergoing potentially curative resection for colorectal cancer. Patients (n=455) who underwent potentially curative resections between 2003 and 2007 were assessed consecutively, and details were recorded in a database. The majority of patients presented for elective surgery (85%) were over the age of 65 years (70%), were male (58%), were deprived (53%), and had TNM stage I/II disease (61%), had preoperative haemoglobin (56%), white cell count (87%) and mGPS 0 (58%) in the normal range. After surgery, 86 (19%) patients developed a postoperative complication; 70 (81%) of which were infectious complications. On multivariate analysis, peritoneal soiling (P<0.01), elevated preoperative white cell count (P<0.05) and mGPS (P<0.01) were independently associated with increased risk of developing a postoperative infection. In elective patients, only the mGPS (OR=1.75, 95% CI=1.17-2.63, P=0.007) was significantly associated with increased risk of developing a postoperative infection. Preoperative elevated mGPS predicts increased postoperative infectious complications in patients undergoing potentially curative resection for colorectal cancer
HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation
We present the results of a comparative study of HI narrow self-absorption
(HINSA), OH, 13CO, and C18O in five dark clouds. The HINSA follows the
distribution of the emission of the carbon monoxide isotopologues, and has a
characteristic size close to that of 13CO. This confirms that the HINSA is
produced by cold HI which is well mixed with molecular gas in well-shielded
regions. The ratio of the atomic hydrogen density to total proton density for
these sources is 5 to 27 x 10^{-4}. Using cloud temperatures and the density of
HI, we set an upper limit to the cosmic ray ionization rate of 10^{-16} s^{-1}.
Comparison of observed and modeled fractional HI abundances indicates ages for
these clouds to be 10^{6.5} to 10^{7} yr. The low values of the HI density we
have determined make it certain that the time scale for evolution from an
atomic to an almost entirely molecular phase, must be a minimum of several
million years. This clearly sets a lower limit to the overall time scale for
star formation and the lifetime of molecular clouds
Simulation Study of Chic -> J/Psi + gamma Detection with J/Psi -> e+ e- in pp Collisions
We present Monte Carlo preliminary results about the feasibility to detect
the Chic family in p-p collisions at 14 TeV in the ALICE Central Barrel at CERN
LHC. The Chic1 and Chic2 were forced to decay in the channel J/Psi + gamma ->
e+ e- + gamma and were merged with a proton-proton non-biased collision. After
MonteCarlo transport and simulation of the detector response, the e+, e- and
converted gamma were reconstructed and identified in the ALICE ITS, TPC and TRD
detectors. Separate signals corresponding to gamma from Chic1 and from Chic2
were observed. The position and relative weight of the fit to gaussians agreed
with the input values within the statistical limits. Similar studies will be
done for Pb-Pb collisions
Recurrent allopolyploidizations diversify ecophysiological traits in marsh orchids (Dactylorhiza majalis s.l.).
Whole-genome duplication has shaped the evolution of angiosperms and other organisms, and is important for many crops. Structural reorganization of chromosomes and repatterning of gene expression are frequently observed in allopolyploids, with physiological and ecological consequences. Recurrent origins from different parental populations are widespread among polyploids, resulting in an array of lineages that provide excellent models to uncover mechanisms of adaptation to divergent environments in early phases of polyploid evolution. We integrate here transcriptomic and ecophysiological comparative studies to show that sibling allopolyploid marsh orchid species (Dactylorhiza, Orchidaceae) occur in different habitats (low nutrient fens vs. meadows with mesic soils) and are characterized by a complex suite of intertwined, pronounced ecophysiological differences between them. We uncover distinct features in leaf elemental chemistry, light-harvesting, photoprotection, nutrient transport and stomata activity of the two sibling allopolyploids, which appear to match their specific ecologies, in particular soil chemistry differences at their native sites. We argue that the phenotypic divergence between the sibling allopolyploids has a clear genetic basis, generating ecological barriers that maintain distinct, independent lineages, despite pervasive interspecific gene flow. This suggests that recurrent origins of polyploids bring about a long-term potential to trigger and maintain functional and ecological diversity in marsh orchids and other groups
Measurement of the Crab nebula polarization at 90 GHz as a calibrator for CMB experiments
CMB experiments aiming at a precise measurement of the CMB polarization, such
as the Planck satellite, need a strong polarized absolute calibrator on the sky
to accurately set the detectors polarization angle and the cross-polarization
leakage. As the most intense polarized source in the microwave sky at angular
scales of few arcminutes, the Crab nebula will be used for this purpose. Our
goal was to measure the Crab nebula polarization characteristics at 90 GHz with
unprecedented precision. The observations were carried out with the IRAM 30m
telescope employing the correlation polarimeter XPOL and using two orthogonally
polarized receivers. We processed the Stokes I, Q, and U maps from our
observations in order to compute the polarization angle and linear polarization
fraction. The first is almost constant in the region of maximum emission in
polarization with a mean value of alpha_Sky=152.1+/-0.3 deg in equatorial
coordinates, and the second is found to reach a maximum of Pi=30% for the most
polarized pixels. We find that a CMB experiment having a 5 arcmin circular beam
will see a mean polarization angle of alpha_Sky=149.9+/-0.2 deg and a mean
polarization fraction of Pi=8.8+/-0.2%.Comment: Accepted for publication in A&A, 9 pages, 4 figure
Analysis of lesion localisation at colonoscopy: outcomes from a multi-centre U.K. study
Background:
Colonoscopy is currently the gold standard for detection of colorectal lesions, but may be limited in anatomically localising lesions. This audit aimed to determine the accuracy of colonoscopy lesion localisation, any subsequent changes in surgical management and any potentially influencing factors.
Methods:
Patients undergoing colonoscopy prior to elective curative surgery for colorectal lesion/s were included from 8 registered U.K. sites (2012–2014). Three sets of data were recorded: patient factors (age, sex, BMI, screener vs. symptomatic, previous abdominal surgery); colonoscopy factors (caecal intubation, scope guide used, colonoscopist accreditation) and imaging modality. Lesion localisation was standardised with intra-operative location taken as the gold standard. Changes to surgical management were recorded.
Results:
364 cases were included; majority of lesions were colonic, solitary, malignant and in symptomatic referrals. 82% patients had their lesion/s correctly located at colonoscopy. Pre-operative CT visualised lesion/s in only 73% of cases with a reduction in screening patients (64 vs. 77%; p = 0.008). 5.2% incorrectly located cases at colonoscopy underwent altered surgical management, including conversion to open. Univariate analysis found colonoscopy accreditation, scope guide use, incomplete colonoscopy and previous abdominal surgery significantly influenced lesion localisation. On multi-variate analysis, caecal intubation and scope guide use remained significant (HR 0.35, 0.20–0.60 95% CI and 0.47; 0.25–0.88, respectively).
Conclusion:
Lesion localisation at colonoscopy is incorrect in 18% of cases leading to potentially significant surgical management alterations. As part of accreditation, colonoscopists need lesion localisation training and awareness of when inaccuracies can occur
Quarkonia production at RHIC
Quarkonia (J/Psi, Psi', Upsilon) production provides a sensitive probe of
gluon distributions and their modification in nuclei; and is a leading probe of
the hot-dense (deconfined) matter created in high-energy collisions of heavy
ions. I will discuss our current understanding of the modification of gluon
distributions in nuclei and other cold-nuclear-matter effects in the context of
recent p-p and p(d)-A quarkonia measurements. Then I will review the latest
results for nucleus-nucleus collisions from RHIC, and together with the
baseline results from d-A and p-p collisions, discuss several alternative
explanations for the observed suppressions and future prospects for
distinguishing these different pictures.Comment: 8 pages including figures, writeup of talk given at Strange Quark
Matter 2006, UCLA 26-31 March, 200
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