990 resultados para Contrast media
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The National Library of Finland realizes the Digitization Project of Kindred Languages in 2012–15. The project is financially supported by the Kone Foundation. During this project the National Library of Finland has digitized and made available approximately 1200 monograph and more than 100 newspaper titles in several Uralic languages. The materials are available to both researchers and citizens in the National Library’s Fenno-Ugrica collection. The project will produce digitized materials in the Uralic languages as well as their development tools to support linguistic research and citizen science. The resulting materials will constitute the largest resource for the Uralic languages in the world. Through this project, researchers will gain access to corpora which they have not been able to study before and to which all users will have open access regardless of their place of residence. In my presentation, I will discuss 1) how we utilized the social media (Facebook, Twitter, VKontakte etc) to gain audience for our collection and 2) how the needs of researchers and laymen were met in crowdsourcing.
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We measured visual performance in achromatic and chromatic spatial tasks of mercury-exposed subjects and compared the results with norms obtained from healthy individuals of similar age. Data were obtained for a group of 28 mercury-exposed subjects, comprising 20 Amazonian gold miners, 2 inhabitants of Amazonian riverside communities, and 6 laboratory technicians, who asked for medical care. Statistical norms were generated by testing healthy control subjects divided into three age groups. The performance of a substantial proportion of the mercury-exposed subjects was below the norms in all of these tasks. Eleven of 20 subjects (55%) performed below the norms in the achromatic contrast sensitivity task. The mercury-exposed subjects also had lower red-green contrast sensitivity deficits at all tested spatial frequencies (9/11 subjects; 81%). Three gold miners and 1 riverine (4/19 subjects, 21%) performed worse than normal subjects making more mistakes in the color arrangement test. Five of 10 subjects tested (50%), comprising 2 gold miners, 2 technicians, and 1 riverine, performed worse than normal in the color discrimination test, having areas of one or more MacAdam ellipse larger than normal subjects and high color discrimination thresholds at least in one color locus. These data indicate that psychophysical assessment can be used to quantify the degree of visual impairment of mercury-exposed subjects. They also suggest that some spatial tests such as the measurement of red-green chromatic contrast are sufficiently sensitive to detect visual dysfunction caused by mercury toxicity.
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The aim of this master’s thesis was to examine antecedents of eWOM communication in social media in the higher education context. In order to achieve this goal, eWOM communications of the students’ of international master’s programmes at Lappeenranta University of Technology were studied. The main research question was formulated as follows: What kind of effect do service-, brand-related antecedents, contextual antecedents and moderating factors have on LUT’s international master’s degree students’ eWOM communication in social media regarding their studies? The theory part of the master’s thesis was focused on the discussion of service- and brand related eWOM antecedents, contextual antecedents, as well as moderating relationships between them. The empirical part of the master’s thesis was based on quantitative research method. A web-based survey was carried out among current students of international master’s degree programmes at LUT. Out of 712 e-mail invitations sent, 159 responses were received in total. Thus, response rate was 22%. The results of the study showed that satisfaction, commitment, virtual brand community commitment, need for an advice, positive altruistic concerns, negative altruistic concerns, and attitude towards eWOM communications have an effect on eWOM in higher education context. Several moderating effects on eWOM were determined in the present study as well. On the other hand, it was found that dissatisfaction, loyalty, brand identification, desire to help the organization, need for positive self-enhancement, and social risk perception do not have an effect on eWOM in higher education context.
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Acute otitis media (AOM) is the most prevalent bacterial infection among children. Tympanometry and spectral gradient acoustic reflectometry (SG-AR) are adjunctive diagnostic tools to pneumatic otoscopy. The aim was to investigate the diagnostic accuracy and success rates of tympanometry and SG-AR performed by physicians and nurses. The study populations comprised 515 (I-II), 281 (III), and 156 (IV) outpatients (6-35 months). Physicians performed 4246 tympanometric (I) and SG-AR (II) examinations. Nurses performed 1782 (III) and 753 (IV) examinations at symptomatic and asymptomatic visits, respectively. Pneumatic otoscopy by the physician was the diagnostic standard. The accuracy of test results by physicians or nurses (I-IV) and the proportion of visits with accurate exclusive test results from both ears (III-IV) were analyzed. Type B tympanogram and SG-AR level 5 (<49˚) predicted middle ear effusion (MEE). At asymptomatic visits, type A and C1 tympanograms (peak pressure > -200 daPa) and SG-AR level 1 (>95˚) indicated healthy middle ear. Negative predictive values of type A and C1 tympanograms by nurses in excluding AOM at symptomatic and MEE at asymptomatic visits were 94% and 95%, respectively. Nurses obtained type A or C1 tympanogram from both ears at 94/459 (20%) and 81/196 (41%) of symptomatic and asymptomatic visits, respectively. SG-AR level 1 was rarely obtained from both ears. Type A and C1 tympanograms were accurate in excluding AOM at symptomatic and MEE at asymptomatic visits. However, nurses obtained these tympanograms from both ears only at one fifth of symptomatic visits and less than half of asymptomatic visits.
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Subclinical hypothyroidism (SHT) is a disease for which exact therapeutic approaches have not yet been established. Previous studies have suggested an association between SHT and coronary heart disease. Whether this association is related to SHT-induced changes in serum lipid levels or to endothelial dysfunction is unclear. The aim of this study was to determine endothelial function measured by the flow-mediated vasodilatation of the brachial artery and the carotid artery intima-media thickness (IMT) in a group of women with SHT compared with euthyroid subjects. Triglycerides, total cholesterol, HDL-C, LDL-C, apoprotein A (apo A), apo B, and lipoprotein(a) were also determined. Twenty-one patients with SHT (mean age: 42.4 ± 10.8 years and mean thyroid-stimulating hormone (TSH) levels: 8.2 ± 2.7 µIU/mL) and 21 euthyroid controls matched for body mass index, age and atherosclerotic risk factors (mean age: 44.2 ± 8.5 years and mean TSH levels: 1.4 ± 0.6 µIU/mL) participated in the study. Lipid parameters (except HDL-C and apo A, which were lower) and IMT values were higher in the common carotid and carotid bifurcation of SHT patients with positive serum thyroid peroxidase antibodies (TPO-Ab) (0.62 ± 0.2 and 0.62 ± 0.16 mm for the common carotid and carotid bifurcation, respectively) when compared with the negative TPO-Ab group (0.55 ± 0.24 and 0.58 ± 0.13 mm, for common carotid and carotid bifurcation, respectively). The difference was not statistically significant. We conclude that minimal thyroid dysfunction had no adverse effects on endothelial function in the population studied. Further investigation is warranted to assess whether subclinical hypothyroidism, with and without TPO-Ab-positive serology, has any effect on endothelial function.
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Invokaatio: D.F.G.
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Enrichment of culture media with amino acids improves embryo development. However, little is known about the specific action of each amino acid during embryogenesis. The present study was undertaken to examine the effect of L-glutamine (Gln) and tryptophan (Trp) on mouse embryo hatching, expansion and viability in vitro. Blastocysts were collected from 6- to 8-week-old female BALB/c mice (N = 30) and cultured in M2 medium containing either 0.125, 0.25 or 0.5 mM Trp, 1 mM Gln, or M2 alone. Gln significantly increased (100%; P < 0.05) blastocyst hatching at 24 h compared to M2 alone or Trp; moreover, Trp inhibited blastocyst hatching when compared to M2 alone (P < 0.05) at 72 h. In contrast, the percentage of embryos reaching the state of expanded blastocyst at 48 h was significantly higher in medium with 1 mM Gln (66.6%; P < 0.05) or with 0.125 mM Trp (61.1%; P < 0.05). Unexpectedly, Trp increased the percentage of degenerated blastocysts after 48 h (67.7%; P < 0.05), while Gln preserved blastocyst viability. These results suggest that Gln may enhance blastocyst hatching, expansion and viability in vitro.
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The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P < 0.05, ANOVA). Blue-yellow chromatic functions showed no specific tuning shape; however, at high spatial frequencies the evoked potentials showed higher contrast sensitivity than the psychophysical methods (P < 0.05, ANOVA). Evoked potentials can be used reliably to evaluate chromatic red-green CSFs in agreement with psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.
Differential effects of aging on spatial contrast sensitivity to linear and polar sine-wave gratings
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Changes in visual function beyond high-contrast acuity are known to take place during normal aging. We determined whether sensitivity to linear sine-wave gratings and to an elementary stimulus preferentially processed in extrastriate areas could be distinctively affected by aging. We measured spatial contrast sensitivity twice for concentric polar (Bessel) and vertical linear gratings of 0.6, 2.5, 5, and 20 cycles per degree (cpd) in two age groups (20-30 and 60-70 years). All participants were free of identifiable ocular disease and had normal or corrected-to-normal visual acuity. Participants were more sensitive to Cartesian than to polar gratings in all frequencies tested, and the younger adult group was more sensitive to all stimuli tested. Significant differences between sensitivities of the two groups were found for linear (only 20 cpd; P<0.01) and polar gratings (all frequencies tested; P<0.01). The young adult group was significantly more sensitive to linear than to circular gratings in the 20 cpd frequency. The older adult group was significantly more sensitive to linear than to circular gratings in all spatial frequencies, except in the 20 cpd frequency. The results suggest that sensitivity to the two kinds of stimuli is affected differently by aging. We suggest that neural changes in the aging brain are important determinants of this difference and discuss the results according to current models of human aging.
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Vascular calcification decreases compliance and increases morbidity. Mechanisms of this process are unclear. The role of oxidative stress and effects of antioxidants have been poorly explored. We investigated effects of the antioxidants lipoic acid (LA) and tempol in a model of atherosclerosis associated with elastocalcinosis. Male New Zealand white rabbits (2.5-3.0 kg) were fed regular chow (controls) or a 0.5% cholesterol (chol) diet+104 IU/day vitamin D2 (vitD) for 12 weeks, and assigned to treatment with water (vehicle, n=20), 0.12 mmol·kg-1·day-1 LA (n=11) or 0.1 mmol·kg-1·day-1 tempol (n=15). Chol+vitD-fed rabbits developed atherosclerotic plaques associated with expansive remodeling, elastic fiber disruption, medial calcification, and increased aortic stiffness. Histologically, LA prevented medial calcification by ∼60% and aortic stiffening by ∼60%. LA also preserved responsiveness to constrictor agents, while intima-media thickening was increased. In contrast to LA, tempol was associated with increased plaque collagen content, medial calcification and aortic stiffness, and produced differential changes in vasoactive responses in the chol+vitD group. Both LA and tempol prevented superoxide signals with chol+vitD. However, only LA prevented hydrogen peroxide-related signals with chol+vitD, while tempol enhanced them. These data suggest that LA, opposite to tempol, can minimize calcification and compliance loss in elastocalcionosis by inhibition of hydrogen peroxide generation.
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The aim of this study was to assess contrast sensitivity for angular frequency stimuli as well as for sine-wave gratings in adults under the effect of acute ingestion of alcohol. We measured the contrast sensitivity function (CSF) for gratings of 0.25, 1.25, 2.5, 4, 10, and 20 cycles per degree of visual angle (cpd) as well as for angular frequency stimuli of 1, 2, 4, 24, 48, and 96 cycles/360°. Twenty adults free of ocular diseases, with normal or corrected-to-normal visual acuity, and no history of alcoholism were enrolled in two experimental groups: 1) no alcohol intake (control group) and 2) alcohol ingestion (experimental group). The average concentration of alcohol in the experimental group was set to about 0.08%. We used a paradigm involving a forced-choice method. Maximum sensitivity to contrast for sine-wave gratings in the two groups occurred at 4 cpd sine-wave gratings and at 24 and 48 cycles/360° for angular frequency stimuli. Significant changes in contrast sensitivity were observed after alcohol intake compared with the control condition at spatial frequency of 4 cpd and 1, 24, and 48 cycles/360° for angular frequency stimuli. Alcohol intake seems to affect the processing of sine-wave gratings at maximum sensitivity and at the low and high frequency ends for angular frequency stimuli, both under photopic luminance conditions.
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Coronary angiography can be a high-risk condition for the incidence of contrast-induced nephropathy (CIN) in elderly patients. Reduced glutathione, under a variety of mechanisms, may prevent CIN in this procedure. We prospectively examined whether hydration with reduced glutathione is superior to hydration alone for prevention of CIN in an elderly Han Chinese population. A total of 505 patients (271 males and 234 females) aged 75 years or older who underwent non-emergency coronary angiography or an intervention were randomly divided into two groups. The treatment group received hydration with reduced glutathione (n=262) and the control group received hydration alone (n=243). Serum creatinine and blood urea nitrogen levels were measured prior to coronary angiography and 48 h after this procedure. The primary endpoint was occurrence of CIN, which was defined as 25% or 44.2 µmol/L above baseline serum creatinine levels 48 h after the procedure. The overall incidence of CIN was 6.49% in the treatment group and 7.41% in the control group, with no significant difference between the groups (P=0.68). In subgroup analysis by percutaneous coronary intervention, no significant differences were found between the two groups. In summary, reduced glutathione added to optimal hydration does not further decrease the risk of CIN in elderly patients undergoing coronary angiography or an intervention.
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This study aimed to evaluate the effect of preoperative imaging techniques on the success and complication rates of ureteroscopy. We performed a retrospective analysis of 736 patients (455 males and 281 females), with a mean age of 45.5±15.2 years (range, 1-88 years), who underwent rigid ureteroscopic procedures for removal of ureteral stones. Patients were divided into 4 groups according to the type of imaging modality used: group I, intravenous urography (n=116); group II, computed tomography (n=381); group III, computed tomography and intravenous urography (n=91), and group IV, ultrasonography and abdominal plain film (n=148). Patients’ demographics, stone size and location, prior shock wave lithotripsy, lithotripsy technique, operation time, success rate, and rate of intraoperative complications were compared among the groups. There were no significant differences in success and complication rates among the groups. The stone-free rate after primary ureteroscopy was 87.1% in group I, 88.2% in group II, 96.7% in group III, and 89.9% in group IV (P=0.093). The overall incidence of intraoperative complications was 11.8%. According to the modified Satava classification system, 6.1% of patients had grade 1, 5.1% had grade 2, and 0.54% had grade 3 complications. Intraoperative complications developed in 12.1% of patients in group I, 12.6% of patients in group II, 7.7% of patients in group III, and 12.2% of patients in group IV (P=0.625). Our findings clearly demonstrate that ureteroscopic treatment of ureteral stones can be safely and effectively performed with no use of contrast study imaging, except in doubtful cases of anatomical abnormalities.
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Tutkimuksen tavoite on selvittää digitaalisen sisällön ominaisuuksia, jotka vaikuttavat ryhtyvätkö kuluttajat jakamaan, tykkäämään ja kommentoimaan sitä sosiaalisessa mediassa. Tällä pyritään auttamaan yrityksiä ymmärtämään paremmin viraalisuutta, jotta he pystyisivät tuottamaan ja julkaisemaan nettisivuillaan ja sosiaalisessa mediassa parempaa sisältöä, jota kuluttajat jakaisivat enemmän. Tutkimus toteutetaan muodostamalla hypoteeseja mahdollisista ominaisuuksista kirjallisuuden perusteella ja testaamalla niitä regressioanalyyseillä empiirisessä osiossa. Tulokset paljastavat yhdeksän piirrettä, jotka lisäävät viraalisuutta: kiinnostavuus, neutraalisuus, yllättävyys, viihdyttävyys, epäkäytännöllisyys, artikkelin ja Facebook julkaisun pituus, eri sisältö taktiikoiden käyttö (erityisesti blogit ja kuvat lisäävät viraalisuutta) sekä kun mielipidevaikuttaja tai kuuluisuus jakaa sisällön.
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The purpose of this qualitative research is to analyze western-based companies’ social media usage in internationalization into China and to identify social media presence’ impact on the internationalization process. Additionally, the benefits and challenges a western company may face while using social media in China will be illustrated. Competitive advantages, knowledge, networks and relations, and costs and risks could be identified as the key antecedents for successful internationalization. A great social media presence could create a competitive advantage for a western company while competitive advantages may be communicated in social media marketing, knowledge and networks can be enhanced and utilized in internationalization via social media two-way communication. The biggest benefit for internationalization resulted from decreased marketing costs due to cost-effectiveness of social media. The results revealed that cost effective brand awareness was the main benefit from the social media usage in internationalization into China. However, companies struggled with the limited resources and despite of understanding the importance of Chinese social media, lacked sufficient resources for the social media operations. Companies should determine clear strategy and goals that they are willing to achieve via social media in internationalization process, and allocate required resources according to the social media strategy. Localization of the social media operations is important in China, and business-to-consumer companies tend to benefit more from the social media presence. Business-to-business companies may increase the brand’s credibility by successful Chinese social media operations.