692 research outputs found
Temperature responses of some North AtlanticCladophora species (Chlorophyceae) in relation to their geographic distribution
Distance Dependence in the Solar Neighborhood Age-Metallicity Relation
The age-metallicity relation for F and G dwarf stars in the solar
neighborhood, based on the stellar metallicity data of Edvardsson et al.
(1993), shows an apparent scatter that is larger than expected considering the
uncertainties in metallicities and ages. A number of theoretical models have
been put forward to explain the large scatter. However, we present evidence,
based on Edvardsson et al. (1993) data, along with Hipparcos parallaxes and new
age estimates, that the scatter in the age-metallicity relation depends on the
distance to the stars in the sample, such that stars within 30 pc of the Sun
show significantly less scatter in [Fe/H]. Stars of intermediate age from the
Edvardsson et al. sample at distances 30-80 pc from the Sun are systematically
more metal-poor than those more nearby. We also find that the slope of the
apparent age-metallicity relation is different for stars within 30 pc than for
those stars more distant. These results are most likely an artifact of
selection biases in the Edvardsson et al. star sample. We conclude that the
intrinsic dispersion in metallicity at fixed age is < 0.15 dex, consistent with
the < 0.1 dex scatter for Galactic open star clusters and the interstellar
medium.Comment: 15 pages, 5 figures, uses AASTex aaspp4 style; accepted for
publication in the Astrophysical Journa
Transarterial RAdioembolization versus ChemoEmbolization for the treatment of hepatocellular carcinoma (TRACE) : study protocol for a randomized controlled trial
Background: Hepatocellular carcinoma is a primary malignant tumor of the liver that accounts for an important health problem worldwide. Only 10 to 15% of hepatocellular carcinoma patients are suitable candidates for treatment with curative intent, such as hepatic resection and liver transplantation. A majority of patients have locally advanced, liver restricted disease (Barcelona Clinic Liver Cancer (BCLC) staging system intermediate stage). Transarterial loco regional treatment modalities offer palliative treatment options for these patients; transarterial chemoembolization (TACE) is the current standard treatment. During TACE, a catheter is advanced into the branches of the hepatic artery supplying the tumor, and a combination of embolic material and chemotherapeutics is delivered through the catheter directly into the tumor. Yttrium-90 radioembolization (Y-90-RE) involves the transarterial administration of minimally embolic microspheres loaded with Yttrium-90, a beta-emitting isotope, delivering selective internal radiation to the tumor. Y-90-RE is increasingly used in clinical practice for treatment of intermediate stage hepatocellular carcinoma, but its efficacy has never been prospectively compared to that of the standard treatment (TACE). In this study, we describe the protocol of a multicenter randomized controlled trial aimed at comparing the effectiveness of TACE and Y-90-RE for treatment of patients with unresectable (BCLC intermediate stage) hepatocellular carcinoma.
Methods/design: In this pragmatic randomized controlled trial, 140 patients with unresectable (BCLC intermediate stage) hepatocellular carcinoma, with Eastern Cooperative Oncology Group performance status 0 to 1 and Child-Pugh A to B will be randomly assigned to either Y-90-RE or TACE with drug eluting beads. Patients assigned to Y-90-RE will first receive a diagnostic angiography, followed by the actual transarterial treatment, which can be divided into two sessions in case of bilobar disease. Patients assigned to TACE will receive a maximum of three consecutive transarterial treatment sessions. Patients will undergo structural follow-up for a timeframe of two years post treatment. Post procedural magnetic resonance imaging (MRI) will be performed at one and three months post trial entry and at three-monthly intervals thereafter for two years to assess tumor response. Primary outcome will be time to progression. Secondary outcomes will be overall survival, tumor response according to the modified RECIST criteria, toxicities/adverse events, treatment related effect on total liver function, quality of life, treatment-related costs and cost-effectiveness
Differential miRNA expression profiles in cumulus and mural granulosa cells from human pre-ovulatory follicles
BACKGROUND: mural granulosa cells (MGCs) and cumulus cells (CCs) are two specialized cell types that differentiate from a common progenitor during folliculogenesis. Although these two cell types have specialized functions and gene expression profiles, little is known about their microRNA (miRNA) expression patterns.OBJECTIVE: to describe the miRNA profile of mural and cumulus granulosa cells from human pre-ovulatory follicles Methods: using small RNA sequencing, we definedinvestigated the miRNA expression profiles of human primary MGCs and CCs, isolated from healthy women undergoing ovum pick-up for in vitro fertilization (IVF).RESULTS: small RNA sequencing revealed expression of several hundreds of miRNAs in MGCsMGC and CCsCC with 53 miRNAs being significantly differentially expressed between MGCs and CCs. We validated differential expression for miR-146a-5p, miR-149-5p, miR-509-3p and miR-182-5p by RT-qPCR. Analysis of proven targets revealed 37 targets for miR-146a-5p, 43 for miR-182-5p, 2 for miR-509-3p and 9 for miR-149-5p. Gene ontology (GO) analysis for these 4 target gene sets revealed enrichment of 12 GO terms for miR-146a-5p and 10 for miR-182-5p. The GO term ubiquitin-like protein conjugation was enriched within both miRNA target gene sets.CONCLUSION: we generated miRNA expression profiles for MGCs and CCs and identified several differentially expressed miRNAs.</p
Role of age in presentation, response to therapy and outcome of autoimmune hepatitis
Background: Few studies with diverging results and a small sample size have compared autoimmune hepatitis (AIH) in the elderly to younger patients.Aim: To unbiasedly investigate the role of age in behaviour and treatment outcome of AIH.Methods: All patients with probable or definite AIH type 1 in four tertiary academic centres were included in this retrospective- and since 2006 prospective-cohort study. Influence of age on presentation, remission and outcome of AIH were investigated.Results: 359 patients were included. Presence of cirrhosis at AIH diagnosis around 30% was independent of age. ALAT was higher at age 30-60 years on AIH diagnosis, and above age 60 there were less acute onset, less jaundice and more concurrent autoimmune disease. Remission was reached in 80.2%, incomplete remission in 18.7%, only 1.1% (all aged 50-65) was treatment-refractory. Age was not an independent predictor of remission, while cirrhosis was. Above age 45 there was more diabetes, above age 60 more loss of remission. Rate of progression to cirrhosis was 10% in the 10 years after diagnosis and unrelated to age at AIH diagnosis. With onset below age 30, there was more development of decompensated cirrhosis over time. With higher age at AIH diagnosis there was a lower survival free of liver-related death or liver transplantation.Conclusions: AIH presents at all ages. Age influences features at diagnosis, but not response to treatment, while survival without liver-related death or liver transplantation decreases with higher age at diagnosis.</p
Evaluation of robustly optimised intensity modulated proton therapy for nasopharyngeal carcinoma
BACKGROUND AND PURPOSE: To evaluate the dosimetric changes occurring over the treatment course for nasopharyngeal carcinoma (NPC) patients treated with robustly optimised intensity modulated proton therapy (IMPT). MATERIALS AND METHODS: 25 NPC patients were treated to two dose levels (CTV1: 70Gy, CTV2: 54.25Gy) with robustly optimised IMPT plans. Robustness evaluation was performed over 28 error scenarios using voxel-wise minimum distributions to assess target coverage and voxel-wise maximum distributions to assess possible hotspots and critical organ doses. Daily CBCT was used for positioning and weekly repeat CTs (rCT) were taken, on which the plan dose was recalculated and robustly evaluated. Deformable image registration was used to warp and accumulate the nominal, voxel-wise minimum and maximum rCT dose distributions. Changes to target coverage, critical organ and normal tissue dose between the accumulated and planned doses were investigated. RESULTS: 2 patients required a plan adaptation due to reduced target coverage. The D98% in the accumulated voxel-wise minimum distribution was higher than planned for CTV1 in 24/25 patients and for CTV2 in 20/25 patients. Maximum doses to the critical organs remained acceptable in all patients. Other normal tissue doses showed some variation as a result of soft tissue deformations and weight change. Normal tissue complication probabilities for grade ≥2 dysphagia and grade ≥2 xerostomia remained similar to planned values. CONCLUSION: Robustly optimised IMPT plans, in combination with volumetric verification imaging and adaptive planning, provided robust target coverage and acceptable OAR dose variation in our NPC cohort when accumulated over longitudinal data
Normal Globular Cluster Systems in Massive Low Surface Brightness Galaxies
We present the results of a study of the globular cluster systems of 6
massive spiral galaxies, originally cataloged as low surface brightness
galaxies but here shown to span a wide range of central surface brightness
values, including two intermediate to low surface brightness galaxies. We used
the Advanced Camera for Surveys on board HST to obtain photometry in the F475W
and F775W bands and select sources with photometric and morphological
properties consistent with those of globular clusters. A total of 206
candidates were identified in our target galaxies. From a direct comparison
with the Galactic globular cluster system we derive specific frequency values
for each galaxy that are in the expected range for late-type galaxies. We show
that the globular cluster candidates in all galaxies have properties consistent
with globular cluster systems of previously studied galaxies in terms of
luminosity, sizes and color. We establish the presence of globular clusters in
the two intermediate to low surface brightness galaxies in our sample and show
that their properties do not have any significant deviation from the behavior
observed in the other sample galaxies. Our results are broadly consistent with
a scenario in which low surface brightness galaxies follow roughly the same
evolutionary history as normal (i.e. high surface) brightness galaxies except
at a much lower rate, but require the presence of an initial period of star
formation intense enough to allow the formation of massive star clusters.Comment: 14 pages, 6 figures. AJ accepte
Emission Line Spectroscopy of a Damped Lyman-alpha Absorbing Galaxy at z = 0.437
We present Keck/LRIS spectra of a candidate damped Lyman-alpha (DLA) galaxy
toward the QSO 3C196 (z_em = 0.871). The DLA absorption system has a redshift
of z_DLA = 0.437, and a galaxy at 1.5" from the QSO has been identified in high
resolution imaging with WFPC2/HST. We have detected emission lines of [O II]
3727A, Hbeta, [O III] 5007A, Halpha and [N II] 6584A at the absorption
redshift. Based on the emission lines, we have found the redshift of the galaxy
to be z_em = 0.4376 +/- 0.0006. The emission lines also enabled us to calculate
the extinction-corrected luminosities and metallicity indicators using
established indices based on line strengths of different emission lines. These
indicators suggest that the ISM of the DLA galaxy has a high metallicity
comparable to or perhaps twice as much as solar (e.g. 12+log (O/H) = 8.98 +/-
0.07). Based on the strengths of Halpha and on the reddening derived from the
relative strengths of Halpha and Hbeta, the star formation rate is 4.7 +/- 0.8
M_solar/yr. This places the galaxy in the range of gas-rich spiral galaxies.Comment: 24 pages, 7 figures, 2 tables, accepted for publication in A
Dissecting the luminosity function of the Coma cluster of galaxies using CFHT wide field images
[Abridged] We determined the luminosity function (LF) of the Coma cluster
galaxies selected by luminosity, and the LF bi-variate in central brightness.
The Coma cluster and control fields were imaged using the CFH12K (42x28 arcmin)
and UH8K (28x28 arcmin) wide-field cameras at the CFHT. Selected HST images
were used for testing. Quantities were derived from measurements in at least
two colors, which have the following features: (1) Galaxies as faint as three
times the luminosity of the brightest globular clusters are in the completeness
region of our data. (2) We have a complete census (in the explored region) of
low surface brightness galaxies with central surface brightness galaxies almost
as low as the faintest so far cataloged ones. (3) The explored area is among
the largest ever sampled with CCDs at comparable depth for any cluster of
galaxies. (4) The error budget includes all sources of errors known to date.
Using HST images we also discovered that blends of globular clusters, not
resolved in individual components due to seeing, look like dwarf galaxies when
observed from the ground and are numerous and bright. The derived Coma LF is
relatively steep (alpha=-1.4) over the 11 magnitudes sampled, but the slope and
shape depend on color. A large population of faint low surface brightness
galaxies was discovered, representing the largest contributor (in number) to
the LF at faint magnitudes. We found a clear progression for a faintening of
the LF from high surface brightness galaxies (mu~20 mag/arcsec2) to galaxies of
very faint central brightnesses (mu~24.5 mag/arcsec2), and some evidence for a
steepening. Compact galaxies, usually classified as stars and therefore not
included in the LF, are found to be a minor population in Coma.Comment: ApJ, in pres
Deep-water macroalgae from the Canary Islands: new records and biogeographical relationships
Due to the geographical location and paleobiogeography of the Canary Islands, the
seaweed flora contains macroalgae with different distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae recently collected around the Canarian archipelago are discussed. These are Bryopsidella neglecta (Berthotd) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck, Hincksia onslowensis (Amsler et Kapraun)P.C. Silva, Syringoderma floridana Henry, Peyssonnelia harveyana J. Agardh, Cryptonemia seminervis(C. Agardh) J. Agardh, Botryodadia wynnei Ballantine, Gloiocladia blomquistii (Searles) R. E.Norris, PIahchrysis peltata (W. R. Taylor) P. Huv4 et H. Huv4, Leptofauchea brasiliensis Joly, and Sarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae,support the strong affinity of the Canary Islands seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western Atlantic regions
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