225 research outputs found
Crystal structure and electronic states of tripotassium picene
The crystal structure of potassium doped picene with an exact stoichiometry
(K3C22H14, K3picene from here onwards) has been theoretically determined within
Density Functional Theory allowing complete variational freedom of the crystal
structure parameters and the molecular atomic positions. A modified herringbone
lattice is obtained in which potassium atoms are intercalated between two
paired picene molecules displaying the two possible orientations in the
crystal.Along the c-axis, organic molecules alternate with chains formed by
three potassium atoms. The electronic structureof the doped material resembles
pristine picene, except that now the bottom of the conduction band is occupied
by six electrons coming from the ionized K atoms (six per unit cell).
Wavefunctions remain based mainly on picene molecular orbitals getting their
dispersion from intralayer edge to face CH/pi bonding, while eigenenergies have
been modified by the change in the electrostatic potential. The small
dispersion along the c-axis is assigned to small H-H overlap. From the
calculated electronic density of states we expect metallic behavior for
potassium doped picene.Comment: Published version: 8 twocolumn pages, 7 color figures, 2 structural
.cif files include
The interplay between double exchange, super-exchange, and Lifshitz localization in doped manganites
Considering the disorder caused in manganites by the substitution of Mn by Fe
or Ga, we accomplish a systematic study of doped manganites begun in previous
papers. To this end, a disordered model is formulated and solved using the
Variational Mean Field technique. The subtle interplay between double exchange,
super-exchange, and disorder causes similar effects on the dependence of T_C on
the percentage of Mn substitution in the cases considered. Yet, in
LaCaMnGaO our results suggest a quantum
critical point (QCP) for , associated to the localization of
the electronic states of the conduction band. In the case of
LaCaMnFeO (with ) no such QCP is expected.Comment: 6 pages + 3 postscript figures. Largely extended discussio
Tricritical Point and the Doping Dependence of the Order of the Ferromagnetic Phase Transition of La1-xCaxMnO3
We report the doping dependence of the order of the ferromagnetic metal to
paramagnetic insulator phase transition in La1-xCaxMnO3. At x = 0.33,
magnetization and specific heat data show a first order transition, with an
entropy change (2.3 J/molK) accounted for by both volume expansion and the
discontinuity of M ~ 1.7 Bohr magnetons via the Clausius-Clapeyron equation. At
x = 0.4, the data show a continuous transition with tricritical point exponents
alpha = 0.48+/- 0.06, beta = 0.25+/- 0.03, gamma = 1.03+/- 0.05, and delta =
5.0 +/- 0.8. This tricritical point separates first order (x<0.4) from second
order (x>0.4) transitions.Comment: 14 pages, including 4 figures: i.e. 10 pages of text and 4 pages of
figures. to appear in Physical Review Letters (accepted
Impact of non-adherence to radiotherapy on 1-year survival in cancer patients in Catalonia, Spain
This study aims to assess the effects of non-adherence to external beam radiation therapy in cancer patients receiving treatment with a curative. This retrospective cohort study collected health records data for all cancer patients treated with external beam radiotherapy with curative intent in 2016 in Catalonia, Spain. Adherence was defined as having received at least 90% of the total dose prescribed. A logistic regression model was used to assess factors related to non-adherence, and its association with one-year survival was evaluated using Cox regression. The final sample included 8721 patients (mean age 63.6 years): breast cancer was the most common tumour site (38.1%), followed by prostate and colon/rectum. Treatment interruptions prolonged the total duration of therapy in 70.7% of the patients, and 1.0% were non-adherent. Non-adherence was associated with advanced age, female gender, and some localization of primary tumour (head and neck, urinary bladder, and haematological cancers). The risk of death in non-adherent patients was higher than in adherent patients (hazard ratio [HR] 1.63, 95% confidence interval 0.97-2.74), after adjusting for the potential confounding effect of age, gender, tumour site and comorbidity. Non-adherence to radiotherapy, as measured by the received dose, is very low in our setting, and it may have an impact on one-year survival
ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases
The objective of this document was to standardise published cardiopulmonary exercise testing (CPET) protocols for improved interpretation in clinical settings and multicentre research projects. This document: 1) summarises the protocols and procedures used in published studies focusing on incremental CPET in chronic lung conditions; 2) presents standard incremental protocols for CPET on a stationary cycle ergometer and a treadmill; and 3) provides patients’ perspectives on CPET obtained through an online survey supported by the European Lung Foundation. We systematically reviewed published studies obtained from EMBASE, Medline, Scopus, Web of Science and the Cochrane Library from inception to January 2017. Of 7914 identified studies, 595 studies with 26 523 subjects were included. The literature supports a test protocol with a resting phase lasting at least 3 min, a 3-min unloaded phase, and an 8- to 12-min incremental phase with work rate increased linearly at least every minute, followed by a recovery phase of at least 2–3 min. Patients responding to the survey (n=295) perceived CPET as highly beneficial for their diagnostic assessment and informed the Task Force consensus. Future research should focus on the individualised estimation of optimal work rate increments across different lung diseases, and the collection of robust normative data.The document facilitates standardisation of conducting, reporting and interpreting cardiopulmonary exercise tests in chronic lung diseases for comparison of reference data, multi-centre studies and assessment of interventional efficacy. http://bit.ly/31SXeB
Recommendation of RILEM TC 271-ASC: New accelerated test procedure for the assessment of resistance of natural stone and fired-clay brick units against salt crystallization
This recommendation is devoted to testing the resistance of natural stone and fired-clay brick units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the durability of porous building materials against salt crystallization through a laboratory method that allows for accelerated testing without compromising the reliability of the results. The new procedure is designed to replicate salt damage caused by crystallization near the surface of materials as a result of capillary transport and evaporation. A new approach is proposed that considers the presence of two stages in the salt crystallization test. In the first, the accumulation stage, salts gradually accumulate on or near the surface of the material due to evaporation. In the second, the propagation stage, damage initiates and develops due to changes in moisture content and relative humidity that trigger salt dissolution and crystallization cycles. To achieve this, two types of salt were tested, namely sodium chloride and sodium sulphate, with each salt tested separately. A methodology for assessing the salt-induced damage is proposed, which includes visual and photographical observations and measurement of material loss. The procedure has been preliminarily validated in round robin tests
Type D patients report poorer health status prior to and after cardiac rehabilitation compared to non-type D patients
Background: Type D personality is an emerging risk factor in coronary artery disease (CAD). Cardiac rehabilitation (CR) improves outcomes, but little is known about the effects of CR on Type D patients. Purpose: We examined (1) variability in Type D caseness following CR, (2) Type D as a determinant of health status, and (3) the clinical relevance of Type D as a determinant of health status compared to cardiac history. Methods: CAD patients (n = 368) participating in CR completed the Type D Scale, the Short-Form Health Survey 36 pre- and post-CR, and the Hospital Anxiety and Depression Scale pre-CR, to assess health status and depressive and anxious symptomatology, respectively. Results: The prevalence of Type D decreased from 26.6% to 20.7% (p = 0.012) following CR, but Type D caseness remained stable in 81% of patients. Health status significantly improved following CR [F(1,359) = 17.48, p < 0.001], adjusting for demographic and clinical factors and anxious and depressive symptoms. Type D patients reported poorer health status [F(1,359) = 10.40, p = 0.001], with the effect of Type D being stable over time [F(1,359) = 0.49, p = 0.48]. Patients with a cardiac history benefited less from CR [F(1,359) = 5.76, p = 0.02]. The influence of Type D on health status was larger compared to that for cardiac history, as indicated by Cohen's effect size index. Conclusions: Type D patients reported poorer health status compared to non-Type D patients pre- and post-CR. In the majority of patients, CR did not change Type D caseness, with Type D being associated with a stable and clinically relevant effect on outcome. These high-risk patients should
Efficacy and safety of alirocumab in insulin-treated patients with type 1 or type 2 diabetes and high cardiovascular risk:Rationale and design of the ODYSSEY DM-INSULIN trial
Aims: The coadministration of alirocumab, a PCSK9 inhibitor for treatment of hypercholesterolaemia, and insulin in diabetes mellitus (DM) requires further study. Described here is the rationale behind a phase-IIIb study designed to characterize the efficacy and safety of alirocumab in insulin-treated patients with type 1 (T1) or type 2 (T2) DM with hypercholesterolaemia and high cardiovascular (CV) risk. Methods: ODYSSEY DM-INSULIN (NCT02585778) is a randomized, double-blind, placebo-controlled, multicentre study that planned to enrol around 400 T2 and up to 100 T1 insulin-treated DM patients. Participants had low-density lipoprotein cholesterol (LDL-C) levels at screening. ≥. 70. mg/dL (1.81. mmol/L) with stable maximum tolerated statin therapy or were statin-intolerant, and taking (or not) other lipid-lowering therapy; they also had established CV disease or at least one additional CV risk factor. Eligible patients were randomized 2:1 to 24. weeks of alirocumab 75. mg every 2. weeks (Q2W) or a placebo. Alirocumab-treated patients with LDL-C. ≥. 70. mg/dL at week 8 underwent a blinded dose increase to 150. mg Q2W at week 12. Primary endpoints were the difference between treatment arms in percentage change of calculated LDL-C from baseline to week 24, and alirocumab safety. Results: This is an ongoing clinical trial, with 76 T1 and 441 T2 DM patients enrolled; results are expected in mid-2017. Conclusion: The ODYSSEY DM-INSULIN study will provide information on the efficacy and safety of alirocumab in insulin-treated individuals with T1 or T2 DM who are at high CV risk and have hypercholesterolaemia not adequately controlled by the maximum tolerated statin therapy
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