1,721,292 research outputs found
Loudspeakers performance variance due to components and assembly process - Field assessment
Full text linkThis paper is the continuation of the study presented at the past convention "AES Berlin 2017-142nd International Convention" regarding the main causes of scrap during the production of a typical midrange loudspeaker. Various samples with reference and modified components parameters have been built and characterized in terms of frequency response, total harmonic distortion and electrical-mechanical parameters. In addition, a second set of samples has been built using reference components but varying the assembly process parameters and these samples also have been characterized as the previous ones. After measurements performed both in an anechoic chamber and in a real production line, a new set of measurements has been done inside a production car, in order to check if the results obtained in the preceding study would have been confirmed by field measurements. In more detail, authors aim was to verify that critical components individuated in the former paper would also have a relevant role after samples installation in a vehicle
Loudspeakers performance variance due to components and assembly process
Full text linkThis paper presents an experimental study of the main causes of scrap during the production of a typical
midrange loudspeaker. After analyzing the most critical components of a transducer, various samples with
reference and defected components have been built and characterized in terms of frequency response and
distortion. In addition, a second set of samples has been built using reference components but varying the
assembly process parameters; these samples also have been characterized as the previous ones. Measurements
have been performed both in an anechoic chamber and in a real production line and, by the analysis of acquired
data, the authors have individuated the most influential components and assembly parameters in terms of
required performance
Immunosuppressive regimens and outcomes of inflammatory bowel disease patients requiring kidney transplantation
No full textPatients with Patients with inflammatory bowel disease (IBD) can develop extra-renal complications and as a result, suffer from end stage renal failure requiring kidney transplantation (KT). A brief review of available literature revealed that IBD patients undergoing KT have shorter overall survival rates compared to their controls. Literature reporting steroid regimens and survival outcomes specific to IBD and post kidney transplant are scarce and these studies have small sample sizes thus making it difficult to draw accurate conclusions. Further research is required in the form of a randomized controlled study to clarify the effect and mechanism of steroid immunosuppression on the prognosis of renal transplant recipients and explore new treatment schemes.
Singh U, Singh B, Bellini MI. Immunosuppressive regimens and outcomes of inflammatory bowel disease patients requiring kidney transplantation. World J Transplant 2022; 12(2): 21-23 [PMID: 35211378 DOI: 10.5500/wjt.v12.i2.21]. A brief review of available literature revealed that IBD patients undergoing KT have shorter overall survival rates compared to their controls. Literature reporting steroid regimens and survival outcomes specific to IBD and post kidney transplant are scarce and these studies have small sample sizes thus making it difficult to draw accurate conclusions. Further research is required in the form of a randomized controlled study to clarify the effect and mechanism of steroid immunosuppression on the prognosis of renal transplant recipients and explore new treatment schemes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Organ preservation. Which temperature for which organ?
Full text linkIn 1954, Joseph Murray performed the first successful human organ transplant from a live kidney donor, Richard Herrick, into the donor’s twin, Robert. Since no form of organ preservation was available, the surgeries happen in two simultaneous operating rooms. In this way, the kidney damage subsequent to the lack of blood supply before the vascular anastomoses between Richard’s vessels and Robert’s kidney were confectioned, was reduced to the shortest possible (1). Richard recovered well and died in 1962 for recurrence of his original nephritis disease.
Seventy years later from Murray’s pioneering surgery, the optimal graft preservation prior to implantation in the recipient’s body remains one of the major challenges in transplantation. The primary graft function and its long-term outcomes are dependant from the ischaemia-reperfusion injury (IRI)(2), with considerable parenchymal damage occurring after retrieval and before implant, during the preservation period. There is evidence that different organs have different resistance thresholds to the ischaemic insult, and these thresholds could be affected by the preservation modality (3, 4).
The three main organ preservation techniques include static cold storage (SCS), Hypothermic Machine Perfusion (HMP) and Normothermic Machine Perfusion (NMP); to date, SCS is still the most common preservation modality because of its simplicity and lower cost, despite growing evidence of a higher risk of subsequent transplant failure (5).
Literature has shown that organs retrieved from extend criteria donors (ECD) and donors after cardiocirculatory death (DCD), are more susceptible to the IRI when compared to standard donors (6, 7). Thus, to keep expanding the donor pool with marginal organs, it is paramount to tailor the preservation modality to the characteristics of the single isolated graft (8).
Ex situ organ perfusion was introduced in the early 1900s by Charles Lindbergh and Alexis Carrel, who developed the first idea of HMP to preserve kidneys and vessels (9), but it was not until 1967, when Belzer transplanted a deceased donor kidney after 17 hours of preservation, including HMP (10). The graft worked immediately post transplantation.
What is the rationale to cool the organ down before implantation? Is there a temperature paradigm? We know that in kidneys, hypothermia slows down the cell metabolism, thus reducing oxygen requirements during the ischaemic period outside the human body (11). Yet, there is no evidence on the gold standard temperature for the rest of the human grafts. Unpublished data from our laboratory, assessed the role of different temperature in terms of human cell survival after the ischaemic insult: we found that the optimal temperature storage is the same for kidney and heart (4 C°), but higher for lung (7C°) and lower for the liver (1C°). Despite these findings are limited to in vitro models, in 1998, we copyrighted a device allowing modification of the temperature according to the human graft to transport (12). This was a compact bio air conditioner able to switch and maintain a set temperature between -20 C° and + 37C°, to allow storage of different organs and tissues from the donor’s hospital to the recipient’s site. Is 37 C°, the human body temperature, a possible way forward? The NRP basic principle of organ preservation is to minimize the deleterious effects of ischemia and anoxia while the organ is outside the human body. The hypothermic setting slows the cell metabolism and demand for oxygen, but it does not prevent the chemical processes that cause the ischemic injury during the preservation period. Despite the possibility to deliver oxygen during HMP, in what is so called the Hypothermic Oxygenated Machine Perfusion (HOPE), in preliminary studies, NRP seems to provide in addition of oxygen, a platform to repair marginal organs by delivering therapeutics (13).
In conclusion, one size might not fit all. It is still not clear which temperature setting is to prefer to another for an optimal organ preservation. Current research is directed at different techniques to improve practices, assessment and reconditioning of organ viability pre-transplantation
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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