A Detailed Metallogenic Study of the McFaulds Lake Chromite Deposits, Northern Ontario

The Black Label, Black Thor and Big Daddy chromite deposits are a series of chromitite layers that are hosted by the 2734.5 +/-1.0 Ma ‘Ring of Fire’ Intrusion in the McFaulds Lake greenstone belt of Northern Ontario. Over 4200 electron microprobe analyses and 142 laser ablation ICP-MS analyses were performed on chromite and record individual fractionation sequences of chromitite below the metre scale. In comparing results, the dunite-hosted Black Thor chromites are higher grade with 53 to 49 wt. % Cr2O3, more primitive than Black Label chromites at 50 to 46 wt. % Cr2O3. Heterogeneous growth of orthopyroxene oikocrysts in Black Label chromitite accounts for increased silicate content. Massive chromitite at Big Daddy shows remarkable homogeneity at 50 to 51 wt. % Cr2O3. The homogeneity of the massive ore is attributed to development of chromitite layers by continuous magma pooling. A strong linear regression of increasing Cr2O3 with MgO from disseminated to massive chromite at all deposits indicates the primary chromite compositions are magmatic. Elemental variation in the chromites include decreasing Cr, increasing Fe, slightly decreasing Al and decreasing Mg due to differentiation. Near constant low-Al compositions are characteristic of komatiitic chromite. Laser ablation results show trends of depletion in Ti, V, Zn, Mn and Co, but enrichment in Ni and Sc, consistent with fractionation of chromitite. The chromitites contain mineral inclusions of pyroxene, igneous amphibole, and phlogopite that have very magnesian contents suggesting a source in the ultramafic magma. The host dunite and pyroxenite have negative Nb-Ta and Zr-Hf anomalies that signify an inherent contamination of ultramafic magma by TTG crust. The Ring of Fire Intrusion has been autohydrated, causing pervasive serpentinization and tremolitization of host dunite and pyroxenite. Secondary ferrichromite with higher wt. % FeOT and Cr2O3 forms as rims on primary chromites, thereby enriching the Cr content of the ore. The rims of primary chromites are leached of Mg and Al leaving high Cr and Fe. The released Mg and Al forms magnesian clinochlore that contains up to 9 wt. % Cr2O3

Is the perceived impact of disciplinary procedures on medical doctors’ professional practice associated with working in an open culture and feeling supported?:A questionnaire among medical doctors in the Netherlands who have been disciplined

Introduction Disciplinary procedures can have a negative impact on the professional functioning of medical doctors. In this questionnaire study, doctors’ experience with open culture and support during a disciplinary procedure is studied to determine whether open culture and support are associated with perceived changes in the professional practice of doctors. Methods All doctors who received a warning or a reprimand from the Dutch Medical Disciplinary Board between July 2012 and August 2016 were invited to fill in a 60-item questionnaire concerning open culture, perceived support during the disciplinary procedure and the impact of the procedure on professional functioning as reported by doctors themselves. The response rate was 43% (n=294). Results A majority of doctors perceive their work environment as a safe environment in which to talk about and report incidents (71.2% agreed). Respondents felt supported by a lawyer or legal representative and colleagues (92.8% and 89.2%, respectively). The disciplinary procedure had effects on professional practice. Legal support and support from a professional confidant and a professional association were associated with fewer perceived changes to professional practice. Conclusion Our study shows that doctors who had been disciplined perceive their working environment as open. Doctors felt supported by lawyers and/or legal representatives and colleagues. Legal support was associated with less of a perceived impact on doctors’ professional practice

Assessment of “silent” restenosis and long-term follow-up after successful angioplasty in single vessel coronary artery disease: The value of quantitative exercise electrocardiography and quantitative coronary angiography

AbstractExercise electrocardiographic (ECG) testing during follow-up after coronary angioplasty is widely applied to evaluate the efficacy of angioplasty, even in asymptomatic patients. One hundred forty-one asymptomatic patients without previous myocardial infarction underwent quantitative exercise ECG testing and quantitative coronary angiography 1 to 6 months after successful angioplasty in single vessel coronary artery disease to 1) determine the value of exercise ECG testing to detect “silent” restenosis, and 2) assess the long-term prognostic value of exercise ECG testing and coronary angiography.The prevalence of restenosis (defined as ≥50% luminal narrowing at the dilation site) was 12% in this selected study group. Of 26 patients with an abnormal exercise ECG (ST segment depression ≥0.1 mV), only 4 (15%) showed recurrence of stenosis. Sensitivity and specificity for detection of restenosis were 24% and 82%, respectively.One hundred thirty-four patients (95%) were followed up 1 to 64 months (mean 35) after exercise ECG testing and coronary angiography. Thirty-two patients (24%) experienced a cardiac event: in 25 patients (78%) the initial event was recurrent angina pectoris (New York Heart Association class III or IV) and in 7 patients (22%) it was myocardial infarction, although cardiac death did not occur. The mean interval between exercise ECG testing and the initial cardiac events was 14 months (range 1 to 55), whereas 47% of the initial events took place ≤6 months after exercise ECG testing. An abnormal exercise test result and angiographic restenosis had, respectively, a predictive value of 36% and 41% and a relative risk of 1.7 and 1.9. Gender, age and extent of ST segment depression were not related to the occurrence of cardiac events.Thus, exercise ECG testing is not the technique of choice to detect silent restenosis after coronary angioplasty of single vessel coronary artery disease. An abnormal exercise test result and angiographic evidence of restenosis had only limited value in predicting long-term outcome in this patient group

Impact of percutaneous coronary intervention timing on 5-year outcome in patients with non-ST-segment elevation acute coronary syndromes. The ‘wait a day’ approach might be safer

Background The OPTIMA trial was a randomised multicentre trial exploring the influence of the timing of percutaneous coronary intervention (PCI) on patient outcomes in an intermediate to high risk non-ST-elevation acute coronary syndrome (NSTE-ACS) population. In order to decide the best treatment strategy for patients presenting with NSTEACS, long-term outcomes are essential. Methods Five-year follow-up data from 133 of the 142 patients could be retrieved (94 %). The primary endpoint was a composite of death and spontaneous myocardial infarction (MI). Spontaneous MI was defined as MI occurring more than 30 days after randomisation. Secondary endpoints were the individual outcomes of death, spontaneous MI or re-PCI. Results No significant difference with respect to the primary endpoint was observed (17.8 vs. 10.1 %; HR 1.55, 95 % CI: 0.73–4.22, p = 0.21). There was no significant difference in mortality rate. However, spontaneous MI was significantly more common in the group receiving immediate PCI (11.0 vs. 1.4 %; HR 4.46, 95 % CI: 1.21–16.50, p = 0.02). We did not find a significant difference between the groups with respect to re-PCI rate. Conclusion There was no difference in the composite of death and spontaneous MI. The trial suggests an increased long-term risk of spontaneous MI for patients treated with immediate PCI

Platform Dependent Verification: On Engineering Verification Tools for 21st Century

The paper overviews recent developments in platform-dependent explicit-state LTL model checking.Comment: In Proceedings PDMC 2011, arXiv:1111.006

Maintenance of long-term clinical benefit with sirolimus-eluting coronary stents - Three-year results of the RAVEL trial

Background— The use of sirolimus-eluting coronary stents has been associated with a nearly complete elimination of restenosis at 6 months and with a very low 1-year incidence of major adverse cardiac events (MACE). This analysis examined whether these beneficial effects persist over the longer term. Methods and Results— This multicenter trial randomly assigned 238 patients to revascularization of single, de novo, native coronary artery lesions with sirolimus-eluting versus conventional bare-metal stents. Survival free from target lesion revascularization (TLR), target vessel failure (TVF), and MACE up to 3 years of follow-up was compared between the 2 treatment groups. Complete data sets were available in 94.2% of patients treated with sirolimus-eluting stents and in 94.1% of patients randomized to the control group. The cumulative 1-, 2-, and 3-year event-free survival rates were 99.2%, 96.5%, and 93.7% for TLR and 95.8%, 92.3%, and 87.9% for TVF, respectively, in the sirolimus-eluting stent group, versus 75.9%, 75.9%, and 75.0% for TLR and 71.2%, 69.4%, and 67.3% for TVF in the control group (P<0.001 for both comparisons at 3 years). Rates of MACE at 3 years were 15.8% in patients randomly assigned to sirolimus-eluting stents versus 33.1% in patients assigned to bare-metal stents (P=0.002). One patient treated with a sirolimus-eluting stent died of a cardiac cause between 12 and 36 months. Conclusions— Treatment of de novo coronary stenosis with sirolimus-eluting stents was associated with a sustained clinical benefit and very low rates of TLR and of other MACE up to 3 years after device implantation