589 research outputs found
Molecular-Marker-Mediated Characterization of Favorable Exotic Alleles at Quantitative Trait Loci in Maize
Exotic maize (Zea mays L.) germplasm, shown to be useful for developing improved temperate cultivars, has remained little used partly because of many inherent shortcomings. Five F2 populations, developed from South American and U.S. germplasm, were used to detect favorable factors of exotic origin at quantitative trait loci (QTL) with isozymes and RFLPs. A number of traits of agronomic importance, including grain yield, were measured on F2 individuals and/or F3 families grown in several environments. Many QTLs, mostly with small effects, were identified. Major QTLs for grain yield and number of ears per plant were located on chromosomes 3 and 6. Stability of QTLs across environments was high. Favorable alleles of exotic origin were found at QTLs for several traits including grain yield and number of ears per plant. Most of these alleles also showed undesirable effects on other traits, however. Nevertheless, the superiority of exotic alleles over adapted alleles was demonstrated clearly at a few QTLs, re-affirming the usefulness of exotic germplasm for temperate maize breeding
Robust Beamforming with Pilot Reuse Scheduling in a Heterogeneous Cloud Radio Access Network
© 1967-2012 IEEE. This paper considers a downlink ultradense heterogeneous cloud radio access network, which guarantees seamless coverage and can provide high date rates. In order to reduce channel state information (CSI) feedback overhead, incomplete intercluster CSI is considered, i.e., each remote radio head or macro base station only measures the CSI from user equipments (UEs) in its serving cluster. To reduce pilot consumption, pilot reuse among UEs is assumed, resulting in imperfect intracluster CSI. A two-stage optimization problem is then formulated. In the first stage, a pilot scheduling algorithm is proposed to minimize the sum mean square error (MSE) of all channel estimates. Specifically, the minimum number of required pilots along with a feasible pilot allocation solution are first determined by applying the Dsatur algorithm, and adjustments based on the defined level of pilot contamination are then carried out for further improvement. Based on the pilot allocation result obtained in the first stage, the second stage aims at maximizing the sum spectral efficiency (SE) of the network by optimizing the beam vectors. Due to incomplete intercluster CSI and imperfect intracluster CSI, an explicit expression of each UE's achievable rate is unavailable. Hence, a lower bound on the achievable rate is derived based on Jensen's inequality, and an alternative robust transmission design algorithm along with its distributed realization are then proposed to maximize the derived tight lower bound. Simulation results show that compared with the existing algorithms, the system performance can be greatly improved by the proposed algorithms in terms of both sum MSE and sum SE
Die Rangfolge psychischer und sozialer PrĂ€diktoren und Kriterien fĂŒr die Prognose Herztransplantierter
Bei 44 Herztransplantierten wurden prĂ€operativ und bis zu einem und drei Jahre postoperativ psychiatrisch/psychologische Untersuchungen durchgefĂŒhrt und psychosoziale Daten erhoben. Die PrĂ€diktoren und Kriterien fĂŒr eine gute Prognose wurden ihrer Rangfolge nach hierarchisiert. Es ergab sich folgende PrĂ€diktorrangfolge: 1. die eindeutige Motivation und der unauffĂ€llige psychopathologische Befund, 2. der gute soziale RĂŒckhalt und die vor der Transplantation zum Ausdruck gebrachte positive Berufsperspektive, 3. das BewuĂtsein der Geborgenheit durch die Familie und die reife psychologische Verarbeitung der Herzerkrankung und der bevorstehenden Herztransplantation, 4. der fortgeschrittene Schweregrad der Herzerkrankung (Schweregrad IV NYHA), 5. der relativ geringe Fernsehkonsum (weniger als an 4 Abenden), und 6. u. a. noch lebende Eltern und das Vorhandensein von Kindern. FĂŒr die 7 prognostischen Kriterien lieĂ sich folgendeKriterienrangfolge ermitteln: 1. die soziale Reintegration, 2. die Lebenszufriedenheit, 3. die Compliance und der psychopathologische Befund, 4. die berufliche Rehabilitation, und 5. die körperliche Belastbarkeit und der körperliche Zustand. Die Studie zeigt, daĂ es eine unterschiedliche Gewichtung psychosozialer Faktoren vor und nach der Herztransplantation gibt, und daĂ die soziale Reintegration der beste Indikator fĂŒr eine erfolgreiche Herztransplantation ist.44 patients underwent psychiatric/psychological and psychosocial examinations before and for one to three years after heart transplantation. Predictors and prognostic criteria for a good result were established according to the rank of their significance. The rank sequence for the predictors were 1. strong motivation and absence of psychiatric symptomatology, 2. good social support and determination to return to work after transplantation, 3. the feeling of being cared for by the family and a mature psychological coping with the heart disease and the expected transplantation, 4. advanced heart failure (stage IV NYHA), 5. watching TV less than 4 evenings a week, 6. parents still living and having oneâs own children. The rank sequence for the 7 prognostic criteria for a good result after heart transplantation were 1. social reintegration, 2. being content with life. 3. good compliance and absence of psychopathology, 4. returning to work, and 5. physical exercise tolerance and general physical condition. The study shows that there is a different magnitude of significance for psychosocial factors before and after heart transplantation and that social reintegration is the best indicator for a good result after heart transplantation
Combined Free-running 4D anatomical and flow MRI with native contrast using Synchronization of Neighboring Acquisitions by Physiological Signals (SyNAPS).
BACKGROUND
4D flow MRI often relies on the injection of gadolinium- or iron-oxide-based contrast agents to improve vessel delineation. In this work, a novel technique is developed to acquire and reconstruct 4D flow data with excellent dynamic visualization of blood vessels but without the need for contrast injection. Synchronization of Neighboring Acquisitions by Physiological Signals (SyNAPS) uses Pilot Tone (PT) navigation to retrospectively synchronize the reconstruction of two free-running 3D radial acquisitions, to create co-registered anatomy and flow images.
METHODS
Thirteen volunteers and two Marfan Syndrome patients were scanned without contrast agent using one free-running fast interrupted steady-state (FISS) sequence and one free-running phase-contrast MRI (PC-MRI) sequence. PT signals spanning the two sequences were recorded for retrospective respiratory motion correction and cardiac binning. The magnitude and phase images reconstructed, respectively, from FISS and PC-MRI, were synchronized to create SyNAPS 4D flow datasets. Conventional 2D flow data were acquired for reference in ascending (AAo) and descending aorta (DAo). The blood-to-myocardium contrast ratio, dynamic vessel area, net volume, and peak flow were used to compare SyNAPS 4D flow with Native 4D flow (without FISS information) and 2D flow. A score of 0-4 was given to each dataset by two blinded experts regarding the feasibility of performing vessel delineation.
RESULTS
Blood-to-myocardium contrast ratio for SyNAPS 4D flow magnitude images (1.5±0.3) was significantly higher than for Native 4D flow (0.7±0.1, p<0.01), and was comparable to 2D flow (2.3±0.9, p=0.02). Image quality scores of SyNAPS 4D flow from the experts (MP: 1.9±0.3, ET: 2.5±0.5) were overall significantly higher than the scores from Native 4D flow (MP: 1.6±0.6, p=0.03, ET: 0.8±0.4, p<0.01) but still significantly lower than the scores from the reference 2D flow datasets (MP: 2.8±0.4, p<0.01, ET: 3.5±0.7, p<0.01). The Pearson correlation coefficient between the dynamic vessel area measured on SyNAPS 4D flow and that from 2D flow was 0.69±0.24 for the AAo and 0.83±0.10 for the DAo, whereas the Pearson correlation between Native 4D flow and 2D flow measurements was 0.12±0.48 for the AAo and 0.08±0.39 for the DAo. Linear correlations between SyNAPS 4D flow and 2D flow measurements of net volume (r2=0.83) and peak flow (r2=0.87) were larger than the correlations between Native 4D flow and 2D flow measurements of net volume (r2=0.79) and peak flow (r2=0.76).
DISCUSSION AND CONCLUSION
The feasibility and utility of SyNAPS was demonstrated for joint whole-heart anatomical and flow MRI without requiring ECG gating, respiratory navigators, or contrast agents. Using SyNAPS a high-contrast anatomical imaging sequence can be used to improve 4D flow measurements that often suffer from poor delineation of vessel boundaries in the absence of contrast agents
Effect of Thyroid Hormone Therapy on Fatigability in Older Adults with Subclinical Hypothyroidism: A Nested Study within a Randomized Placebo-Controlled Trial
Background: Fatigue often triggers screening for and treatment of subclinical hypothyroidism. However, data on the impact of levothyroxine on fatigue is limited and previous studies might not have captured all aspects of fatigue. Method: This study is nested within the randomized, placebo-controlled, multicenter TRUST trial, including community-dwelling participants aged =65 and older, with persistent subclinical hypothyroidism (TSH 4.60-19.99 mIU/L, normal free thyroxine levels) from Switzerland and Ireland. Interventions consisted of daily levothyroxine starting with 50 ”g (25 ”g if weight <50 kg or known coronary heart diseases) together with dose adjustments to achieve a normal TSH and mock titration in the placebo group. Main outcome was the change in physical and mental fatigability using the Pittsburgh Fatigability Scale over 1 year, assessed through multivariable linear regression with adjustment for country, sex, and levothyroxine starting dose. Results: Among 230 participants, the mean ± standard deviation (SD) TSH was 6.2 ± 1.9 mIU/L at baseline and decreased to 3.1 ± 1.3 with LT4 (n = 119) versus 5.3 ± 2.3 with placebo (n = 111, p <. 001) after 1 year. After adjustment we found no between-group difference at 1 year on perceived physical (0.2; 95% CI -1.8 to 2.1; p =. 88), or mental fatigability (-1.0; 95% CI -2.8 to 0.8; p =. 26). In participants with higher fatigability at baseline (=15 points for the physical score [n = 88] or =13 points for the mental score [n = 41]), the adjusted between-group differences at 1 year were 0.4 (95% CI -3.6 to 2.8, p =. 79) and -2.2 (95% CI -8.8 to 4.5, p =. 51). Conclusions: Levothyroxine in older adults with mild subclinical hypothyroidism provides no change in physical or mental fatigability
Leadership and capacity building in international chiropractic research: introducing the chiropractic academy for research leadership (CARL).
In an evidence-based health care environment, healthcare professions require a sustainable research culture to remain relevant. At present however, there is not a mature research culture across the chiropractic profession largely due to deficiencies in research capacity and leadership, which may be caused by a lack of chiropractic teaching programs in major universities. As a response to this challenge the Chiropractic Academy for Research Leadership, CARL, was created with the aim of develop a global network of successful early-career chiropractic researchers under the mentorship of three successful senior academics from Australia, Canada, and Denmark. The program centres upon an annual week-long program residential that rotates continental locations over the first three-year cycle and between residentials the CARL fellows work on self-initiated research and leadership initiatives. Through a competivite application process, the first cohort was selected and consists of 13 early career researchers from five professions in seven countries who represent diverse areas of interests of high relevance for chiropractic. The first residential was held in Odense, Denmark, with the second being planned in April 2018 in Edmonton, Canada, and the final residential to be held in Sydney, Australia in 2019
Effect of thyroid hormone therapy on fatigability in older adults with subclinical hypothyroidism: a nested study within a randomized placebo-controlled trial
Background:
Fatigue often triggers screening for and treatment of subclinical hypothyroidism. However, data on the impact of levothyroxine on fatigue is limited and previous studies might not have captured all aspects of fatigue.
Method:
This study is nested within the randomized, placebo-controlled, multicenter TRUST trial, including community-dwelling participants aged â„65 and older, with persistent subclinical hypothyroidism (TSH 4.60â19.99 mIU/L, normal free thyroxine levels) from Switzerland and Ireland. Interventions consisted of daily levothyroxine starting with 50 ÎŒg (25 ÎŒg if weight <50 kg or known coronary heart diseases) together with dose adjustments to achieve a normal TSH and mock titration in the placebo group. Main outcome was the change in physical and mental fatigability using the Pittsburgh Fatigability Scale over 1 year, assessed through multivariable linear regression with adjustment for country, sex, and levothyroxine starting dose.
Results:
Among 230 participants, the mean ± standard deviation (SD) TSH was 6.2 ± 1.9 mIU/L at baseline and decreased to 3.1 ± 1.3 with LT4 (n = 119) versus 5.3 ± 2.3 with placebo (n = 111, p < .001) after 1 year. After adjustment we found no between-group difference at 1 year on perceived physical (0.2; 95% CI â1.8 to 2.1; p = .88), or mental fatigability (â1.0; 95% CI â2.8 to 0.8; p = .26). In participants with higher fatigability at baseline (â„15 points for the physical score [n = 88] or â„13 points for the mental score [n = 41]), the adjusted between-group differences at 1 year were 0.4 (95% CI â3.6 to 2.8, p = .79) and â2.2 (95% CI â8.8 to 4.5, p = .51).
Conclusions:
Levothyroxine in older adults with mild subclinical hypothyroidism provides no change in physical or mental fatigability
Thyroid antibodies and levothyroxine effects in subclinical hypothyroidism: A pooled analysis of two randomized controlled trials
Background: Antithyroid antibodies increase the likelihood of developing overt hypothyroidism, but their clinical utility remains unclear. No large randomized controlled trial (RCT) has assessed whether older adults with subclinical hypothyroidism (SHypo) caused by autoimmune thyroid disease derive more benefits from levothyroxine treatment (LT4). Objective: To determine whether older adults with SHypo and positive antibodies derive more clinical benefits from LT4 than those with negative antibodies. Methods: We pooled individual participant data from two RCTs, Thyroid Hormone Replacement for Untreated Older Adults with Subclinical Hypothyroidism and IEMO 80+. Participants with persistent SHypo were randomly assigned to receive LT4 or placebo. We compared the effects of LT4 versus placebo in participants with and without antiâthyroid peroxidase (TPO) at baseline. The two primary outcomes were 1-year change in Hypothyroid Symptoms and Tiredness scores on the Thyroid-Related Quality-of-Life Patient-Reported Outcome Questionnaire. Results: Among 660 participants (54% women) â„65 years, 188 (28.5%) had positive anti-TPO. LT4 versus placebo on Hypothyroid Symptoms lead to an adjusted between-group difference of â2.07 (95% confidence interval: â6.04 to 1.90) for positive antibodies versus 0.89 (â1.76 to 3.54) for negative antibodies (p for interaction = 0.31). Similarly, there was no treatment effect modification by baseline antibody status for Tiredness scoresâadjusted between-group difference 1.75 (â3.60 to 7.09) for positive antibodies versus 1.14 (â1.90 to 4.19) for negative antibodies (p for interaction = 0.98). Positive anti-TPO were not associated with better quality of life, improvement in handgrip strength, or fewer cardiovascular outcomes with levothyroxine treatment. Conclusions: Among older adults with SHypo, positive antithyroid antibodies are not associated with more benefits on clinical outcomes with LT4
Ethical procedures and patient consent differ in Europe
BACKGROUND: Research ethics approvals, procedures and requirements for institutional research ethics committees vary considerably by country and by type of organisation. OBJECTIVE: To evaluate the requirements and procedures of research ethics committees, details of patient information and informed consent based on a multicentre European trial. DESIGN: Survey of European hospitals participating in the prospective observational study on chronic postsurgical pain (euCPSP) using electronic questionnaires. SETTING: Twenty-four hospitals in 11 European countries. PARTICIPANTS: From the 24 hospitals, 23 local investigators responded; 23 answers were analysed. OUTCOME MEASURES: Comparison of research ethics procedures and committee requirements from the perspective of clinical researchers. Comparison of the institutions' procedures regarding patient information and consent. Description of further details such as costs and the duration of the approval process. RESULTS: The approval process lasted from less than 2 weeks up to more than 2 months with financial fees varying between 0 and 575 âŹ. In 20 hospitals, a patient information sheet of variable length (half page up to two pages) was provided. Requirements for patients' informed consent differed. Written informed consent was mandatory at 12, oral at 10 and no form of consent at one hospital. Details such as enough time for consideration, possibility for withdrawal and risks/benefits of participation were provided in 25 to 30% of the institutions. CONCLUSION: There is a considerable variation in the administrative requirements for approval procedures by research ethics committees in Europe. This results in variation of the extent of information and consent procedures for the patients involved
Obesity, stigma, and responsibility in health care: A synthesis of qualitative studies
Objective: To synthesize research findings on experiences and attitudes about obesity and stigma in health care. Methods: We compiled qualitative studies and applied Noblitt & Hare's meta ethnography to identify, translate, and summarize across studies. Thirteen qualitative studies on experiences and attitudes about obesity and stigma in health care settings were identified and included. Results: The study reveals how stigmatizing attitudes are enacted by health care providers and perceived by patients with obesity. Second-order analysis demonstrated that apparently appropriate advice can be perceived as patronizing by patients with obesity. Furthermore, health care providers indicate that abnormal bodies cannot be incorporated in the medical systems—exclusion of patients with obesity consequently happens. Finally, customary standards for interpersonal respect are legitimately surpassed, and patients with obesity experience contempt as if deserved. Third-order analysis revealed conflicting views between providers and patients with obesity on responsibility, whereas internalized stigma made patients vulnerable for accepting a negative attribution. A theoretical elaboration relates the issues of stigma with those of responsibility. Conclusion: Contradictory views on patients’ responsibility, efforts, knowledge, and motivation merge to internalization of stigma, thereby obstructing healthy coping and collaboration and creating negative contexts for empowerment, self-efficacy, and weight management. Professionals need to develop their awareness for potentially stigmatizing attitudes towards vulnerable patient populations
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