866 resultados para ELECTRONIC POLARIZATION
Resumo:
The electronic structure of the wurtzite-type phase of aluminum nitride has been investigated by means of periodic ab initio Hartree-Fock calculations. The binding energy, lattice parameters (a,c), and the internal coordinate (u) have been calculated. All structural parameters are in excellent agreement with the experimental data. The electronic structure and bonding in AlN are analyzed by means of density-of-states projections and electron-density maps. The calculated values of the bulk modulus, its pressure derivative, the optical-phonon frequencies at the center of the Brillouin zone, and the full set of elastic constants are in good agreement with the experimental data.
Yellow submarine of the Wnt/Frizzled signaling: submerging from the G protein harbor to the targets.
Resumo:
The Wnt/Frizzled signaling pathway plays multiple functions in animal development and, when deregulated, in human disease. The G-protein coupled receptor (GPCR) Frizzled and its cognate heterotrimeric Gi/o proteins initiate the intracellular signaling cascades resulting in cell fate determination and polarization. In this review, we summarize the knowledge on the ligand recognition, biochemistry, modifications and interacting partners of the Frizzled proteins viewed as GPCRs. We also discuss the effectors of the heterotrimeric Go protein in Frizzled signaling. One group of these effectors is represented by small GTPases of the Rab family, which amplify the initial Wnt/Frizzled signal. Another effector is the negative regulator of Wnt signaling Axin, which becomes deactivated in response to Go action. The discovery of the GPCR properties of Frizzled receptors not only provides mechanistic understanding to their signaling pathways, but also paves new avenues for the drug discovery efforts.
Resumo:
BACKGROUND: Poor long-term adherence is an important cause of uncontrolled hypertension. We examined whether monitoring drug adherence with an electronic system improves long-term blood pressure (BP) control in hypertensive patients followed by general practitioners (GPs). METHODS: A pragmatic cluster randomised controlled study was conducted over one year in community pharmacists/GPs' networks randomly assigned either to usual care (UC) where drugs were dispensed as usual, or to intervention (INT) group where drug adherence could be monitored with an electronic system (Medication Event Monitoring System). No therapy change was allowed during the first 2 months in both groups. Thereafter, GPs could modify therapy and use electronic monitors freely in the INT group. The primary outcome was a target office BP<140/90 mmHg. RESULTS: Sixty-eight treated uncontrolled hypertensive patients (UC: 34; INT: 34) were enrolled. Over the 12-month period, the likelihood of reaching the target BP was higher in the INT group compared to the UC group (p<0.05). At 4 months, 38% in the INT group reached the target BP vs. 12% in the UC group (p<0.05), and 21% vs. 9% at 12 months (p: ns). Multivariate analyses, taking account of baseline characteristics, therapy modification during follow-up, and clustering effects by network, indicate that being allocated to the INT group was associated with a greater odds of reaching the target BP at 4 months (p<0.01) and at 12 months (p=0.051). CONCLUSION: GPs monitoring drug adherence in collaboration with pharmacists achieved a better BP control in hypertensive patients, although the impact of monitoring decreased with time.
Resumo:
Purpose. To evaluate the impact of mobile devices and apps on the daily clinical activity of young radiation oncologists. Methods. A web-based questionnaire was sent to 382 young (≤40 years) members of the Italian Association of Radiation Oncology (AIRO). The 14 items investigated the diffusion of mobile devices (smartphones and/or tablets), their impact on daily clinical activity, and possible differences perceived by the participants over time. Results. A total of 158 questionnaires were available for statistical evaluation (response rate 41%). Up to 75% of respondents declared they used an electronic device during their clinical activity. Conversely, 82% considered the impact of smartphones/tables on daily practice low to moderate. Daily device use increased significantly from 2009 to 2012, with high daily use rates rising from 5% to 39.9%. Fulfillment of professional needs was declared by less than 42% of respondents and compliance with app indications by 32%. Almost all physicians desired in 2012 a comprehensive website concerning a variety of apps covering radiation oncologists' needs. Conclusions. Mobile devices are widely used by young Italian radiation oncologists in their daily clinical practice, while the indications so obtained are not always followed. Nevertheless, it would be important to verify the consistency of information found within apps, in order to avoid potential errors that might be detrimental to patients.
Resumo:
Local conditions in the past often limited opportunities for scholarly exchange. But now these limits are gone and the global workplace has replaced them. It is important to react to these changes. Every academic department must now adopt new methods and rethink processes. Another is the intense national and international debate about open access to scholarly knowledge. The Open Access Initiative shows that a change is taking place in the communication process. This change is also important for service departments within research institutions. Libraries, computer centers and related units have to ask themselves how to react appropriately to the new conditions. What services must be changed or redeveloped, and in what quality and quantity should they be offered? This article focuses on changes in the scholarly publication process. It describes both technological changes and the changes needed in people's attitudes.
Resumo:
This paper describes a project led by the Instituto Brasileiro de Informações em Ciência e Tecnologia (Ibict), a government institution, to build a national digital library for electronic theses and dissertations - Bibliteca Digital de Teses e Dissertações (BDTD). The project has been a collaborative effort among Ibict, universities and other research centers in Brazil. The developers adopted a system architecture based on the Open Archives Initiative (OAI) in which universities and research centers act as data providers and Ibict as a service provider. A Brazilian metadata standard for electronic theses and dissertations was developed for the digital library. A toolkit including open source package was also developed by Ibict to be distributed to potential data providers. BDTD has been integrated with the international initiative: the Networked Digital Library of Thesis and Dissertation (NDLTD). Discussions in the paper address various issues related to project design, development and management as well as the role played by Ibict. Conclusions highlight some important lessons learned to date and challenges for the future in expanding the BDTD project.
Resumo:
There is a wide range of evidence to suggest that permeability can be constrained through of induced polarization measurements. For clean sands and sandstones, current mechanistic models of induced polarization predict a relationship between the low-frequency time constant inferred from induced polarization measurements and the grain diameter. A number of observations do, however, disagree with this and indicate that the observed relaxation behavior is rather governed by the so-called dynamic pore radius L. To test this hypothesis, we have developed a set of new scaling relationships, which allow the relaxation time to be computed from the pore size and the permeability to be computed from both the Cole-Cole time constant and the formation factor. Moreover, these new scaling relationships can be also used to predict the dependence of the Cole-Cole time constant as a function of the water saturation under unsaturated conditions. Comparative tests of the proposed new relationships with regard to various published experimental results for saturated clean sands and sandstones as well as for partially saturated clean sandstones, do indeed confirm that the dynamic pore radius L is a much more reliable indicator of the observed relaxation behavior than grain-size-based models.
Resumo:
This study explores the cognitive structures, understood as construct systems, of patients suffering from bulimia nervosa (BN). Previous studies investigated the construct systems of disordered eaters suggesting that they had a higher distance between their construction of the self and the «ideal self», and also more rigidity. In addition to these aspects, this study explored the presence of implicative dilemmas (ID). Thirty two women who met criteria for BN and were treated in a specialized center were compared to a non clinical group composed by 32 women matched by age. All participants were assessed using Repertory Grid Technique (RGT). In BN patients it was more common (71.9%) to find IDs than in controls (18.8%). They also showed higher polarization and higher self-ideal discrepancies (even more for those with a long history of BN). The measures provided by the RGT can be useful for the assessment of self-construction and cognitive conflicts in BN patients and to appreciate their role in this disorder. In addition, this technique could be helpful for clinicians to explore the patient"s constructs system, and specially to identify IDs that could be maintaining the symptoms or hindering change in order to focus on them to facilitate improvement.
Resumo:
The primary objectives of the Electronic Bulletin Board System (BBS) project were to: (1) Provide an electronic communication tool which would link city and county engineering offices to each other and to other governmental agencies for messaging and data sharing; (2) Provide a dial-up site for reference information or files accessible on-demand; and (3) Provide a "stepping stone" to the world of electronic data transfer, recognizing that most local government employees face a huge complex of technology with limited knowledge of computers and communications tools. The system was designed to be as simple as possible, and to require minimal equipment and software cost to the users. The original system was an Apex 386/25 computer with MS-DOS 5.0 software and the final configuration was an HP Vectra XM Pentium 90 with MS-NT 3.51 and Mustang - Wildcat 5.0 software. The users of the BBS were county engineers and their staff, offices in the central office of the Iowa Department of Transportation (DOT) and Resident Construction Engineers at the Iowa DOT. Much of the activity was between the county engineers, and their staffs, and the Iowa DOT offices with which they have ongoing business activities. The BBS contained files for mapping, Internet e-mail service, Accident Location Analysis System (ALAS) data, Iowa DOT bid lettings, and Autocad and Intergraph maps and standards. The 800 line calls were recorded and gave the best indication of the usage and the trends that were being followed. The usage tended to be higher in the winter months when design activities are occurring and lower in the summer months when the construction is in progress. The project was judged a success. The BBS did provide a "stepping stone" to the world of electronic data transfer.
Resumo:
Polychlorinated trityl radicals bearing carboxylate substituents are water soluble persistent radicals that can be used for dynamic nuclear polarization. In contrast to other trityl radicals, the polarization mechanism differs from the classical solid effect. DFT calculations performed to rationalize this behaviour support the hypothesis that polarization is transferred from the unpaired electron to chlorine nuclei and from these to carbon by spin diffusion. The marked differences observed between neutral and anionic forms of the radical will be discussed.