46 research outputs found

    Lens binarity vs limb darkening in close-impact galactic microlensing events

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    Although point caustics harbour a larger potential for measuring the brightness profile of stars during the course of a microlensing event than (line-shaped) fold caustics, the effect of lens binarity significantly limits the achievable accuracy. Therefore, corresponding close-impact events make a less favourable case for limb-darkening measurements than those events that involve fold-caustic passages, from which precision measurements can easily and routinely be obtained. Examples involving later Bulge giants indicate that a ~ 10 % misestimate on the limb-darkening coefficient can result with the assumption of a single-lens model that looks acceptable, unless the precision of the photometric measurements is pushed below the 1 %-level even for these favourable targets. In contrast, measurement uncertainties on the proper motion between lens and source are dominated by the assessment of the angular radius of the source star and remain practically unaffected by lens binarity. Rather than judging the goodness-of-fit by means of a chi^2 test only, run tests provide useful additional information that can lead to the rejection of models and the detection of lens binarity in close-impact microlensing events.Comment: 11 pages in LaTeX2e format, uses 'mn2e.cls', 6 figures in 10 EPS-files embedded. Submitted to MNRA

    Debris discs in the 27 Myr old open cluster IC4665

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    We present Spitzer IRAC and MIPS 24um imaging of members of the 27+/-5Myr old open cluster IC 4665. Models for the assembly of terrestrial planets through planetesimal collisions and mergers predict episodic dust debris discs at this epoch. We determine that 42(+18-13)% of the solar-type (F5-K5) cluster members have excess emission at 24um indicative of these debris discs, the highest frequency of the clusters studied with Spitzer to date. The majority of these discs have intermediate levels of excess (F_24/F_phot < 2), and no source is found to have extreme levels of excess indicative of a recent transient event as opposed to steady-state collisional evolution. We find no evidence of a link between multiplicity and 24um excess in this cluster sample. Only the early-type star TYC424-473-1 (T_eff~8420K) has significant near-infrared excess from 4.5um as measured with IRAC. Two solar-type targets have low significance 8um excess but no significant 24um excess. All other targets show no evidence for near-infrared excess which could indicate the presence of an optically thick primordial disc, demonstrating that the observed 24um excess arises from a debris disc.Comment: 14 pages, 11 figures, accepted for publication in MNRA

    Dust discs around intermediate mass and Sun-like stars in the 16 Myr old NGC 1960 open cluster

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    We present an analysis of Spitzer IRAC (3.6--8um) and MIPS (24um) imaging of members of the 16(+10/-5)Myr old open cluster NGC 1960 (M36). Models of terrestrial planet formation indicate that rocky planets are likely to achieve their final masses at around 10-30Myr, and thus this cluster is at an interesting epoch for planet formation. We find 21 B-F5 type stars and 14 F6-K9 type stars which have 24um excess emission, and thus determine that >30% of B-F5 type stars and >23% of F6-K9 type stars in this cluster have 24um excess emission. These excess frequencies are similar to those observed in other clusters of similar age. Three early type stars have excesses at near-infrared wavelengths. Analysis of their SEDs confirms that these are true debris discs and not remnant primordial or transitional discs. None of the 61 sun-like stars have confirmed near-infrared excess, and we can place a limit on the frequency of 8um excess emission around sun-like stars of <7%. All of the detected excesses are consistent with emission from debris discs and are not primordial.Comment: 16 pages, 10 figures, accepted for publication in MNRAS (tables 1-4 will be available in full online in the electronic version of the paper

    Guidance of adjuvant instillation in intermediate-risk non-muscle invasive bladder cancer by drug screens in patient derived organoids: a single center, open-label, phase II trial.

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    BACKGROUND In intermediate-risk non-muscle invasive bladder cancer (NMIBC) clinical guidelines suggest an adjuvant instillation with a chemotherapeutic agent. However, the agent and regimen are not clearly defined. Worldwide, less than 15% of patients receive this adjuvant chemotherapeutic instillation. We recently developed a pipeline for the generation of patient derived organoids (PDO) in NMIBC. In this phase II trial, we aim to use our in vitro pipeline to select the most effective drug for chemotherapeutic instillation in NMIBC patients. METHODS Patients with first diagnosis of intermediate-risk NMIBC that are directed to transurethral resection of bladder tumor (TURBT) are enrolled. During TURBT, tumor is sampled, and specimens are directed to generate PDO. Once the PDO are formed, drug screens on them for Epirubicin, Mitomycin C, Gemcitabine and Docetaxel are performed. The drug with the highest antitumor activity in vitro will then be selected for 6 adjuvant intravesical instillations once weekly. Thereafter, patients are followed according to clinical guidelines by cystoscopy. DISCUSSION The aim of this trial is to use drug screens in PDO to precise treatment selection for adjuvant instillation therapies in patients with intermediate-risk NMIBC. The ultimate goal of this trial is to reduce the risk of cancer recurrence. In the future, we aim to conduct clinical multicenter trials with an increased sample size, a broader panel of compounds and a focus on the reduction of cancer recurrence by precision delivery of care. Trial registration NCT05024734

    Extraction of Biofilms From Ureteral Stents for Quantification and Cultivation-Dependent and -Independent Analyses

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    Ureteral stenting is a common surgical procedure, which is associated with a high morbidity and economic burden, but the knowledge on the link between biofilms on these stents, morbidity, and the impact of the involved microbiota is still limited. This is partially due to a lack of methods that allow for a controlled extraction of the biofilms from stents. Development of an appropriate in vitro model to assess prevention of biofilm formation by antimicrobial coatings and biomaterials requires a profound understanding of the biofilm composition, including the involved microbiota. This work describes an analytical pipeline for the extraction of native biofilms from ureteral stents for both cultivation-dependent and -independent analysis, involving a novel mechanical abrasion method of passing stent samples through a tapered pinhole. The efficiency of this novel method was evaluated by quantifying the removed biofilm mass, numbers of cultivable bacteria, calcium content, and microscopic stent analysis after biofilm removal using 30 clinical stent samples. Furthermore, the extraction of in vitro formed Escherichia coli biofilms was evaluated by universal 16S quantitative PCR, a cultivation-independent method to demonstrate efficient biofilm removal by the new approach. The novel method enables effective contamination-free extraction of the biofilms formed on ureteral stents and their subsequent quantification, and it represents a useful tool for comprehensive examinations of biofilms on ureteral stents

    The Evolution of Compact Binary Star Systems

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    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

    Comparison of prostatic artery embolisation (PAE) versus transurethral resection of the prostate (TURP) for benign prostatic hyperplasia: randomised, open label, non-inferiority trial

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    OBJECTIVE To compare prostatic artery embolisation (PAE) with transurethral resection of the prostate (TURP) in the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia in terms of patient reported and functional outcomes. DESIGN Randomised, open label, non-inferiority trial. SETTING Urology and radiology departments of a Swiss tertiary care centre. PARTICIPANTS 103 patients aged ≥40 years with refractory lower urinary tract symptoms secondary to benign prostatic hyperplasia were randomised between 11 February 2014 and 24 May 2017; 48 and 51 patients reached the primary endpoint 12 weeks after PAE and TURP, respectively. INTERVENTIONS PAE performed with 250-400 μm microspheres under local anaesthesia versus monopolar TURP performed under spinal or general anaesthesia. MAIN OUTCOMES AND MEASURES Primary outcome was change in international prostate symptoms score (IPSS) from baseline to 12 weeks after surgery; a difference of less than 3 points between treatments was defined as non-inferiority for PAE and tested with a one sided test. Secondary outcomes included further questionnaires, functional measures, magnetic resonance imaging findings, and adverse events; changes from baseline to 12 weeks were compared between treatments with two sided tests for superiority. RESULTS Mean reduction in IPSS from baseline to 12 weeks was -9.23 points after PAE and -10.77 points after TURP. Although the difference was less than 3 points (1.54 points in favour of TURP (95% confidence interval -1.45 to 4.52)), non-inferiority of PAE could not be shown (P=0.17). None of the patient reported secondary outcomes differed significantly between treatments when tested for superiority; IPSS also did not differ significantly (P=0.31). At 12 weeks, PAE was less effective than TURP regarding changes in maximum rate of urinary flow (5.19 15.34 mL/s; difference 10.15 (95% confidence interval -14.67 to -5.63); P<0.001), postvoid residual urine (-86.36 -199.98 mL; 113.62 (39.25 to 187.98); P=0.003), prostate volume (-12.17 -30.27 mL; 18.11 (10.11 to 26.10); P<0.001), and desobstructive effectiveness according to pressure flow studies (56% 93% shift towards less obstructive category; P=0.003). Fewer adverse events occurred after PAE than after TURP (36 70 events; P=0.003). CONCLUSIONS The improvement in lower urinary tract symptoms secondary to benign prostatic hyperplasia seen 12 weeks after PAE is close to that after TURP. PAE is associated with fewer complications than TURP but has disadvantages regarding functional outcomes, which should be considered when selecting patients. Further comparative study findings, including longer follow-up, should be evaluated before PAE can be considered as a routine treatment. TRIAL REGISTRATION Clinicaltrials.gov NCT02054013
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