1,721,213 research outputs found
Modified reverse tapering method to prevent frequency shift of the radiation in the planar undulator
Get PDFThis paper presents a modified reverse tapering method to generate a polarized soft x ray in x-ray free-electron lasers (XFELs) with a higher photon power and a shorter undulator length than the simple linear reverse tapering method. In the proposed method, a few untapered planar undulators are added before the simple linear reverse tapering section of the undulator line. This simple modification prevents the frequency shift of the radiation that occurs when the simple linear reverse tapering method is applied to planar undulators. In the proposed method, the total length of planar undulators decreased in spite of the additional untapered undulators. When the modified reverse tapering method is used with four untapered planar undulators, the total length of the planar undulators is 64.6 m. On the other hand, the required length of the planar undulators is 94.6 m when the simple linear reverse tapering method is used. The proposed method gives us a way to generate a soft x-ray pulse (1.24 keV) with a high degree of polarization (>0.99) and radiation power (>30 GW) at the new undulator line with a 10-GeV electron beam in the Pohang Accelerator Laboratory X-ray Free-Electron Laser. This method can be applied in the existing XFELs in the world without any change in the undulator lines. ? 2017 authors. Published by the American Physical Society.111Ysciescopu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Isolated terawatt sub-attosecond high-energy x-ray pulse generated by an x-ray free-electron laser
No full textThe endless quest for dynamics in natural phenomena has resulted in the generation and application of attosecond pulses to trace electron dynamics in atomic and molecular systems. The next challenge is to generate powerful pulses on the zeptosecond time scale, which is currently inaccessible. Through a simulation study, a new type of x-ray source that can generate an isolated terawatt sub-attosecond pulse at high-energy x rays by combining attosecond pulse technology with free-electron laser technology is proposed. The successful generation of a sub-attosecond pulse necessitates the consideration of nanometer-wide current-spikes, the sub-attosecond pulse amplification, and pulse duration and background noise control. The underlying interaction mechanism between a sub-attosecond pulse and a current-spike is closely investigated using the simulation results. The proposed method is expected to produce an isolated ~700 zs pulse with a peak output of 2.9 TW at a photon energy of 247.5 keV. (C) 2022 Author(s).11Ysciescopu
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
(The) effects of preoperative nursing instruction on the physical and emotional recovery of pediatric surgical patients - an experimental study
No full text간호학과/석사[한글]
The Effects of Preoperative Nursing Instruction on the Physical and Emotional
Recovery of Pediatric Surgical Patients-An Experimental Study.
Shim, Chi Joung
Department of Nursing Graduate School of Yonsei University
(directed by Dr. Chun, San Cho)
Very few studies regarding the effects of preoperative nursing intervention on
children's welfare after surgery have been conducted. The purpose of this study was
1) to evaluate the effects of preoperative nursing instructions on children's
physical recovery and emotional state after surgery and 2) to analyse the
relationship between the effects of preoperative nursing instructions and the age
and general anxiety of child.
The study was conducted from August 15th to October 30th at Severance Hospital,
Seoul, Korea. A total of 41 Pediatric surgical Patients, between the age of 4 to
14, participated in the study. Twenty patients, randomly selected, were visited by
the experimenter in the evening before surgery and received specific preoperative
nursing instructions. These instructions were designed to alleviated emotional
stress and were adopted o the age of child. The postoperative recovery of these
patients were then compared with a randomly selected control group of 21 patients
who received only the routine preoperative care by the staff in the hospital.
Dependent variable were vomiting, pain, medication, ability to void, elevation of
temperature, infection, time between surgery and hospital discharge and
postoparative emotional stress which was measured by the vital signs.
Because of the limitation of the sample size it was difficult to obtain valid
statistical results. However, the analysis of the raw data indicates that;
1) the preoperative nursing instructionsappears to promote physical recovery and
it seems especially effective in preventing elevation of temperature and shortening
the length of the hospital stay,
2) the preoperative nursing instruction also seems to be effective in relieveing
the child's emotional stress(situational anxiety) after surgery,
3) the patient's general anxiety level prooperatively seems to be a predictor of
postoperative problems,
4) the preoperative nursing instructions were and effective means of promoting
physical recovery in every age group as long as the child understood the
instructions.
The above data would seem to indicate that all preoperative pediatric patients
four years of age or older, if they can understand, should have preoperative
nursing instruction in order to alleviate postoperative stress and enhance physical
recovery.
The lvel of general anxiety preoperatively deserves special attention since the
amount of nursing instruction needed seems to vary with the level of anxiety.
[영문]
Very few studies regarding the effects of preoperative nursing intervention on children's welfare after surgery have been conducted. The purpose of this study was 1) to evaluate the effects of preoperative nursing instructions on children's
physical recovery and emotional state after surgery and 2) to analyse the relationship between the effects of preoperative nursing instructions and the age and general anxiety of child.
The study was conducted from August 15th to October 30th at Severance Hospital, Seoul, Korea. A total of 41 Pediatric surgical Patients, between the age of 4 to 14, participated in the study. Twenty patients, randomly selected, were visited by
the experimenter in the evening before surgery and received specific preoperative nursing instructions. These instructions were designed to alleviated emotional stress and were adopted o the age of child. The postoperative recovery of these patients were then compared with a randomly selected control group of 21 patients who received only the routine preoperative care by the staff in the hospital.
Dependent variable were vomiting, pain, medication, ability to void, elevation of temperature, infection, time between surgery and hospital discharge and postoparative emotional stress which was measured by the vital signs.
Because of the limitation of the sample size it was difficult to obtain valid statistical results. However, the analysis of the raw data indicates that;
1) the preoperative nursing instructionsappears to promote physical recovery and it seems especially effective in preventing elevation of temperature and shortening the length of the hospital stay,
2) the preoperative nursing instruction also seems to be effective in relieveing the child's emotional stress(situational anxiety) after surgery,
3) the patient's general anxiety level prooperatively seems to be a predictor of postoperative problems,
4) the preoperative nursing instructions were and effective means of promoting physical recovery in every age group as long as the child understood the instructions.
The above data would seem to indicate that all preoperative pediatric patients four years of age or older, if they can understand, should have preoperative nursing instruction in order to alleviate postoperative stress and enhance physical recovery.
The lvel of general anxiety preoperatively deserves special attention since the amount of nursing instruction needed seems to vary with the level of anxiety.restrictio
Usefulness of Left Ventricular Vortex Flow Analysis for Predicting Clinical Outcomes in Patients with Chronic Heart Failure: A Quantitative Vorticity Imaging Study Using Contrast Echocardiography
No full textThe goal of the study described here was to evaluate whether left ventricular vortex flow parameters, as assessed by contrast echocardiography, enhance prediction of major adverse cardiac events (MACE) in patients with chronic heart failure and systolic dysfunction. A total of 75 patients with contrast echocardiography and systolic dysfunction (ejection fraction 45%) were prospectively enrolled and underwent vortex flow analysis with particle image velocimetry using contrast echocardiography. Vortex flow parameters, including kinetic energy fluctuation (KEF), were evaluated. Patients were followed up for a primary endpoint of MACE that comprised hospital admission for cardiovascular causes and cardiac deaths. Across a median 277-d follow-up, 29 patients (38.7%) experienced MACE. Among these, the incidence of diabetes and the E/e’ ratio were significantly higher in patients with MACE than in those without, whereas the hemoglobin level and ejection fraction were significantly lower. KEF was significantly lower in patients with MACE. In the multivariate analysis, higher KEF was associated with a lower risk of MACE (hazard ratio = 0.18, 95% confidence interval: 0.040.97, p = 0.046). The addition of KEF to a model with conventional parameters (e.g., age, diabetes, ejection fraction and the E/e’ ratio) significantly improved the model’s discrimination. Elevations in the quantitative left ventricular vortex flow parameter, KEF, as determined by contrast echocardiography, are associated with a lower risk of MACE and improved functional status among patients with chronic heart failure
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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