First-principles investigation of organic photovoltaic materials C60_{60}, C70_{70}, [C60_{60}]PCBM, and bis-[C60_{60}]PCBM using a many-body G0W0G_0W_0-Lanczos approach

We present a first-principles investigation of the excited-state properties of electron acceptors in organic photovoltaics including C$_{60}$, C$_{70}$, [6,6]-phenyl-C$_{61}$-butyric-acid-methyl-ester ([C$_{60}$]PCBM), and bis-[C$_{60}$]PCBM using many-body perturbation theory within the Hedin's $G_0W_0$ approximation and an efficient Lanczos approach. Calculated vertical ionization potentials (VIP) and vertical electron affinities (VEA) of C$_{60}$ and C$_{70}$ agree very well with experimental values measured in gas phase. The density of states of all three molecules is also compared to photoemission and inverse photoemission spectra measured on thin-films, exhibiting a close agreement - a rigid energy-gap renormalization owing to intermolecular interactions in the thin-films. In addition, it is shown that the low-lying unoccupied states of [C$_{60}$]PCBM are all derived from the highest-occupied molecular orbitals and the lowest-unoccupied molecular orbitals of fullerene C$_{60}$. The functional side group in [C$_{60}$]PCBM introduces a slight electron transfer to the fullerene cage, resulting in small decreases of both VIP and VEA. This small change of VEA provides a solid justification for the increase of open-circuit voltage when replacing fullerene C$_{60}$ with [C$_{60}$]PCBM as the electron acceptor in bulk heterojunction polymer solar cells.Comment: 9 pages, 4 figures, and 7 table

Raman spectra of disordered oxides from first principles

This thesis is devoted to the study of Raman scattering from first-principles. We develop two different methods to calculate Raman spectra of large model structures. The first method concerns the extension of the perturbative variational approach for the calculation of dielectric tensors to the case of ultrasoft pseudopotentials, allowing a significant improvement in the size of the affordable systems. The second method permits to treat finite electric fields in Car-Parrinello molecular dynamics simulations with periodic boundary conditions. Applied to the calculation of Raman spectra, this approach, in the case of large systems, gives a further significant reduction of the computational effort required to obtain Raman spectra. The methods we develop in the first part of the thesis are then applied to the study of vitreous silica and vitreous boron oxide. By applying our perturbative approach, we obtain the Raman spectrum for a model structure of vitreous silica. The accurate description of the Raman couplings allows us to derive an estimate from the experimental spectrum for the concentration of oxygen atoms in three- and four-membered rings. Finally, we apply the finite field method to calculate the Raman spectrum of a large model structure of vitreous boron oxide. By investigating the contributions to the Raman spectrum from vibrations of different symmetry, we can extract from the experimental spectrum an estimate for the concentration of boron atoms belonging to three-membered rings

The challenge of improving evidence-based therapy adherence in the secondary prevention of coronary artery disease: the next frontier of cardiac rehabilitation

Non-adherence to prescribed drug regimens is an increasing medical problem affecting physicians and patients and contribute to negative outcomes, such as the increased risk of subsequent cardiovascular events. Analysis of various patient populations shows that the choice of drug, its tolerability and the duration of treatment influence the non-adherence. Intervention is required toward patients and health-care providers to improve medication adherence. This review deals about the prevalence of non-adherence to therapy after medical and surgical cardiac event, the risk factors affecting non-adherence and the strategies to implement it. Interventions that may successfully improve adherence should include improved physician compliance with guidelines, patient education and patient reminders, frequent visits or telephone calls from staff, simplification of the patient's drug regimen by reducing the number of pills and daily doses. Since single interventions do not appear efficaceous, it is necessary to establish multiple interventions simultaneously addressing a number of barriers to adherence

Relativistic Solar Cells

Hybrid AMX3 perovskites (A=Cs, CH3NH3; M=Sn, Pb; X=halide) have revolutionized the scenario of emerging photovoltaic technologies. Introduced in 2009 by Kojima et al., a rapid evolution very recently led to 15% efficient solar cells. CH3NH3PbI3 has so far dominated the field, while the similar CH3NH3SnI3 has not been explored for photovoltaic applications, despite the reduced band-gap. Replacement of Pb by the more environment-friendly Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 properties are discussed in light of their exploitation for solar cells, and found to be entirely due to relativistic effects.Comment: 16 pages, 4 figure

Photoelectron properties of DNA and RNA bases from many-body perturbation theory

The photoelectron properties of DNA and RNA bases are studied using many-body perturbation theory within the GW approximation, together with a recently developed Lanczos-chain approach. Calculated vertical ionization potentials, electron affinities, and total density of states are in good agreement with experimental values and photoemission spectra. The convergence benchmark demonstrates the importance of using an optimal polarizability basis in the GW calculations. A detailed analysis of the role of exchange and correlation in both many-body and density-functional theory calculations shows that while self-energy corrections are strongly orbital-dependent, they nevertheless remain almost constant for states that share the same bonding character. Finally, we report on the inverse lifetimes of DNA and RNA bases, that are found to depend linearly on quasi-particle energies for all deep valence states. In general, our G0W0-Lanczos approach provides an efficient yet accurate and fully converged description of quasiparticle properties of five DNA and RNA bases

[Nurse involvement in primary care: it is the key to improve the outcomes in primary and secondary prevention?].

Difficulties in management of risk factors, lifestyle and medications adherence to achieve secondary prevention of ischemic heart disease were described. Many studies indicate that the benefit of cardiac rehabilitaton therapy after acute coronary events is only partially maintained during the following year. Thereafter, new strategies of medical care are needed to improve the long-term outcomes in coronary patients. Nurse co-ordinated, multidisciplinary cardiac rehabilitative programme could help patients to improve their lifestyle, to control their risk factors and to achieve their therapeutic goals for secondary prevention of ischemic heart disease

Lower is better: ENHANCE affair

Ezetimibe lowers the intestinal absorption of cholesterol, being complementary to the effects of statin. To check its efficacy in lowering the carotid intima-media thickness, in 2002 a multicenter international trial called ENHANCE was started, in order to assess by ultrasound the regression of atherosclerotic plaques. The protocol tested the use of simvastatin 80 mg + placebo versus simvastatin 80 mg + ezetimibe 10 mg in 720 randomized patients. Both drugs were well tolerated. Combination therapy was associated with a larger reduction in LDL cholesterol, but there were no differences in the intima-media thickness measured at three sites in the carotid arteries, nor differences in cardiovascular events between the two groups in the trial. These results provoked disappointment of sponsors (Merck, Schering Plough) who, although the results of the trial were available since march 2007, delayed official communication of about 18 months. This led to speculations and rumors among media, American Government, cardiologic scientific associations, and consequences in the Ezetimibe market and at Wall Street. In particular, the American College of Cardiology didn't accept the communication of ENHANCE results to the Late Breaking Trial Session of the Chicago congress, diverting it to another secondary forum. In conclusion, the experience of the ENHANCE trial suggests to pharmaceutical companies, researchers, clinicians, scientific companies and media a deep meditation in order to avoid in the future similar problems in the management of results of medical research

Prevention and treatment of infectious complications after urogenital prosthesis surgery

Prostheses are widely used in urogenital surgery for many decades and have gained a fundamental role in the management of multiple diseases with good results in terms of functionality, aesthetic outcomes and patients\u2019 satisfaction. It is remarkable that prosthetic device vary in term of mechanical sophistication, costs and surgical implantation techniques ranging from simple device widely used in urological practice like testicular prosthesis to highly sophisticated devices as Inflatable Penile Prosthesis (IPP) and Artificial Urinary Sphincter (AUS). Despite continuous implementations of the devices and improvements of surgical implantation techniques infective complications are still fearful and not uncommon events. Risk of infection depends on patients\u2019 individual features, perioperative strategies, implantation techniques and prosthetic devices. Prevent these complications is imperative because the management of prosthesis infection requires removal of the device in most cases. Centres that plan prosthetic implantations should based on these strategies protocols in order to prevent as far as possible infective complications