131,695 research outputs found
Random matrix theory for quantum and classical metastability in local Liouvillians
No full textWe consider the effects of strong dissipation in quantum systems with a notion of locality, which induces a hierarchy of many-body relaxation timescales as shown by K. Wang, F. Piazza, and D. J. Luitz [Phys. Rev. Lett. 124, 100604 (2020)]. If the strength of the dissipation varies strongly in the system, additional separations of timescales can emerge, inducing a manifold of metastable states, to which observables relax first, before relaxing to the steady state. Our simple model, involving one or two "good" qubits with dissipation reduced by a factor alpha < 1 compared to the other "bad" qubits, confirms this picture and admits a perturbative treatment
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Possible graft-related complications in visceral debranching for hybrid B dissection repair.
No full textDalitz plot analyses of B-0 -> (D-DK+)-K-0 and B+-> (D)over-bar(-)D(0)K(+) decays
No full text© 2015, APS Journal
Open treatment of extent IV thoracoabdominal aortic aneurysms
No full textAim. Extent IV thoracoabdominal aortic aneurysm (TAAA) open repair is considered relatively safer to repair than other extents of TAAA in terms of both perioperative mortality and spinal cord ischemia. Our purpose is to report our experience and to perform a literature review regarding extent IV TAAA open repair in order to provide an updated benchmark for comparison with any other alternative strategy in this aortic segment. Methods. From 1993 to 2015 we performed 736 open repairs for TAAA (177 extent I, 196 extent II, 141 extent III, 222 extent IV). In extent IV group there were 164 men (73.9%) and the mean age was 67.4 +/- 9.3 years (range 32-84). The aneurysm etiology was degenerative in 198 patients (95.6%). Twelve patients (5.4%) underwent emergent operation. Totally abdominal approach was used in 22.0% of the cases. Until 2006 left heart bypass (LHBP) and cerebrospinal fluid drainage (CSFD) were almost never performed during extent IV repair. Since 2006 we changed our approach with a more aggressive use of LHBP (22.9%) and CSFD (43.4%) in 83 consecutive extent IV. Renal arteries perfusion was performed with 4 degrees C Ringer's solution until 2009 and with 4 degrees C Custodiol solution since September 2009 to date. Literature search was performed on several databases (PubMed, BioMed-Central, Embase, and the Cochrane Central Register of clinical trials). Research was updated on March 1th 2015. Results. Perioperative mortality in our overall group of TAAA and in the extents IV was 10.7% and 4.9%, respectively (P=0.01); spinal cord ischemia rate 11.4% and 2.7%, respectively (P=0.0001). In the extents IV treated between 2006 and 2015 we observed a further trend of outcomes improvement with a rate of peri-operative mortality and spinal cord ischemia of 1.2%, and 2.4%, respectively. Database searches yielded a total of 767 articles. Excluding non-pertinent titles or abstracts, we retrieved in complete form and assessed 27 studies according to the selection criteria. Nine studies were further excluded because of our pre-specified exclusion criteria. The final 18 manuscripts included a total of 2098 patients. In this group median mortality rate was 4.8% (interquartile range 3-6) and the mean incidence of spinal cord ischemia was 1.56 +/- 1.54%. Conclusion. Perioperative outcomes after extent IV TAAA open repair were significantly better compared to our overall TAAA series. A more aggressive use of CSFD, LHBP and renal perfusion with Custodiol solution allowed a further trend of outcomes improvement in our series of extent IV TAAA open repair. Literature analysis confirmed during extent IV open repair very satisfactory perioperative outcomes with rates of mortality and spinal cord ischemia dropped to under 5% and 2%, respectively. OI tshomba, yamume/0000-0001-8316-4702Aim. Extent IV thoracoabdominal aortic aneurysm (TAAA) open repair is considered relatively safer to repair than other extents of TAAA in terms of both perioperative mortality and spinal cord ischemia. Our purpose is to report our experience and to perform a literature review regarding extent IV TAAA open repair in order to provide an updated benchmark for comparison with any other alternative strategy in this aortic segment. Methods. From 1993 to 2015 we performed 736 open repairs for TAAA (177 extent I, 196 extent II, 141 extent III, 222 extent IV). In extent IV group there were 164 men (73.9%) and the mean age was 67.4 +/- 9.3 years (range 32-84). The aneurysm etiology was degenerative in 198 patients (95.6%). Twelve patients (5.4%) underwent emergent operation. Totally abdominal approach was used in 22.0% of the cases. Until 2006 left heart bypass (LHBP) and cerebrospinal fluid drainage (CSFD) were almost never performed during extent IV repair. Since 2006 we changed our approach with a more aggressive use of LHBP (22.9%) and CSFD (43.4%) in 83 consecutive extent IV. Renal arteries perfusion was performed with 4 degrees C Ringer's solution until 2009 and with 4 degrees C Custodiol solution since September 2009 to date. Literature search was performed on several databases (PubMed, BioMed-Central, Embase, and the Cochrane Central Register of clinical trials). Research was updated on March 1th 2015. Results. Perioperative mortality in our overall group of TAAA and in the extents IV was 10.7% and 4.9%, respectively (P=0.01); spinal cord ischemia rate 11.4% and 2.7%, respectively (P=0.0001). In the extents IV treated between 2006 and 2015 we observed a further trend of outcomes improvement with a rate of peri-operative mortality and spinal cord ischemia of 1.2%, and 2.4%, respectively. Database searches yielded a total of 767 articles. Excluding non-pertinent titles or abstracts, we retrieved in complete form and assessed 27 studies according to the selection criteria. Nine studies were further excluded because of our pre-specified exclusion criteria. The final 18 manuscripts included a total of 2098 patients. In this group median mortality rate was 4.8% (interquartile range 3-6) and the mean incidence of spinal cord ischemia was 1.56 +/- 1.54%. Conclusion. Perioperative outcomes after extent IV TAAA open repair were significantly better compared to our overall TAAA series. A more aggressive use of CSFD, LHBP and renal perfusion with Custodiol solution allowed a further trend of outcomes improvement in our series of extent IV TAAA open repair. Literature analysis confirmed during extent IV open repair very satisfactory perioperative outcomes with rates of mortality and spinal cord ischemia dropped to under 5% and 2%, respectively. OI tshomba, yamume/0000-0001-8316-470
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
The Bolton Treovance endograft: single center experience
No full textAim. In the last two decades, results of endovascular aortic repair (EVAR) for the treatment of infrarenal abdominal aortic aneurysms (AAAs) have significantly improved thanks to the evolution of stent-grafts and endovascular delivery systems. However, further development is still needed to reduce the incidence of complications and secondary reinterventions. We present our initial experience with the Treovance abdominal aortic stent-graft (Bolton Medical, Barcelona, Spain), a new-generation trimodular endovascular device, developed to increase flexibility, lower profile, improve deployment and sealing mechanisms. Methods. We treated 8 patients with anatomically suitable non-ruptured AAA. Results. Primary technical success was obtained in all patients, and no 30-day device-related complications nor deaths were reported. One patient experienced graft limb occlusion at 3 months, and underwent surgical conversion. At 1-year follow-up (completed in 6 patients), no device-related complications nor type I or III endoleak were observed. Conclusion. Initial personal experience with the Treovance abdominal stent-graft was satisfactory with regard to technical success and short-term clinical results. This new-generation endovascular device performed well even in angulated or heavily calcified anatomies. OI tshomba, yamume/0000-0001-8316-470
- …
