4,779 research outputs found
Usefulness of coronary calcium scoring to myocardial perfusion SPECT in the diagnosis of coronary artery disease in a predominantly high risk population
Coronary calcium scoring (CCS) adds to the diagnostic performance of myocardial perfusion single-photon emission computed tomography (SPECT) to assess the presence of significant coronary artery disease (CAD). Patients with a high pre-test likelihood are expected to have a high CCS which potentially could enhance the diagnostic performance of myocardial perfusion SPECT in this specific patient group. We evaluated the added value of CCS to SPECT in the diagnosis of significant CAD in patients with an intermediate to high pre-test likelihood. In total, 129 patients (mean age 62.7 +/- A 9.7 years, 65 % male) with stable anginal complaints and intermediate to high pre-test likelihood of CAD (median 87 %, range 22-95) were prospectively included in this study. All patients received SPECT and CCS imaging preceding invasive coronary angiography (CA). Fractional flow reserve (FFR) measurements were acquired from patients with angiographically estimated 50-95 % obstructive CAD. For SPECT a SSS > 3 was defined significant CAD. For CCS the optimal cut-off value for significant CAD was determined by ROC curve analysis. The reference standard for significant CAD was a FFR of < 0.80 acquired by CA. Significant CAD was demonstrated in 64 patients (49.6 %). Optimal CCS cut-off value for significant CAD was > 182.5. ROC curve analysis for prediction of the presence of significant CAD for SPECT, CCS and the combination of CCS and SPECT resulted in an area under the curve (AUC) of 0.88 (95 % CI 81-94), 0.75 (95 % CI 66-83 %) and 0.92 (95 % CI 87-97 %) respectively. The difference of the AUC between SPECT and the combination of CCS and SPECT was 0.05 (P = 0.12). The addition of CCS did not significantly improve the diagnostic performance of SPECT in the evaluation of patients with a predominantly high pre-test likelihood of CAD
Dialkyldithiophosphate Acids (HDDPs) as Effective Lubricants of SolâGel Titania Coatings in Technical Dry Friction Conditions
The goal of this study was the investigation of
the effectiveness of dialkyldithiophosphate acids (HDDPs)
films in improving the tribological properties of thin, solâ
gel derived titania coatings. Amorphous, anatase, and rutile
titania coatings were obtained using solâgel dipâcoating
deposition after treatment at 100, 500, and 1,000 C,
respectively. Titania coatings were then modified from the
liquid phase by HDDPs acids having dodecyl-(C12), tetradecyl-(C14),
and hexadecyl-(C16) alkyl chains deposited by
dipâcoating (DC) and LangmuirâBlodgett (LB) methods.
The influence of the deposition procedure, the length of the
HDDPs alkyl chain and the type of titania substrate on the
surface morphology and tribological properties were studied.
It was found, using wetting contact angle measurements,
that these modifications of titania coatings decrease
the surface free energy and increase its hydrophobicity.
The surface topography imaged by Atomic force microscopy
(AFM), exhibit island-like or agglomerate features for
the DC deposition method, while smooth topographies
were observed for LB depositions. Tribological tests were
conducted by means of a microtribometer operating in the
normal load range 30â100 mN. An enhancement of tribological
properties was observed upon modification, as
compared to unmodified titania
Perturbative quantum gravity with the Immirzi parameter
We study perturbative quantum gravity in the first-order tetrad formalism.
The lowest order action corresponds to Einstein-Cartan plus a parity-odd term,
and is known in the literature as the Holst action. The coupling constant of
the parity-odd term can be identified with the Immirzi parameter of loop
quantum gravity. We compute the quantum effective action in the one-loop
expansion. As in the metric second-order formulation, we find that in the case
of pure gravity the theory is on-shell finite, and the running of Newton's
constant and the Immirzi parameter is inessential. In the presence of fermions,
the situation changes in two fundamental aspects. First, non-renormalizable
logarithmic divergences appear, as usual. Second, the Immirzi parameter becomes
a priori observable, and we find that it is renormalized by a four-fermion
interaction generated by radiative corrections. We compute its beta function
and discuss possible implications. The sign of the beta function depends on
whether the Immirzi parameter is larger or smaller than one in absolute value,
and the values plus or minus one are UV fixed-points (we work in Euclidean
signature). Finally, we find that the Holst action is stable with respect to
radiative corrections in the case of minimal coupling, up to higher order
non-renormalizable interactions.Comment: v2 minor amendment
Prevalence of neck pain in subjects with metabolic syndrome - a cross-sectional population-based study
<p>Abstract</p> <p>Background</p> <p>Metabolic syndrome (MetS) is increasingly common. Obesity has been suggested to associate with neck pain but prevalence of neck pain in subjects with MetS has not been studied. Aim of this study was to analyse the association between MetS and neck pain.</p> <p>Methods</p> <p>The study population consisted of 1294 middle-aged subjects in PieksÀmÀki, Finland. A total of 399 males and 500 females participated (69%). The mean age of both males and females was 46 years. Clinical and biochemical measurements were taken. The participants filled out a standard questionnaire. Psychological distress was assessed with the 12-item General Health Questionnaire (GHQ-12). Neck pain was defined as neck pain perceived daily. MetS was defined using National Cholesterol Education Program (NCEP) criteria. Statistical comparisons between the groups were performed using a bootstrap-type t-test or Chi-Square test. Risk ratios of having neck pain were calculated using generalised linear models with age, smoking, alcohol use, exercise and GHQ-12 score as covariates.</p> <p>Results</p> <p>The prevalence of MetS was 33% in males and 29% in females. Neck pain was present in 11% (N = 42) of males and 19% (N = 93) of females (P < 0.001). The prevalence of neck pain was 7.9% (95% CI, 4.9% to 12%) among male subjects without MetS and 16% (95% CI, 10% to 23%) among those with MetS. The respective proportions among females were 16% (95% CI, 12% to 20%) and 25% (95% CI, 18% to 33%). The multivariate analysis showed an increased risk of neck pain in males with MetS (RR 2.1, 95% CI, 1.2 to 3.7, P = 0.010) and in females with MetS (RR 1.5, 95% CI, 1.0 to 2.1, P = 0.040).</p> <p>Conclusions</p> <p>MetS was associated with neck pain. This association was stronger in males, but the prevalence of neck pain was higher in females. Prospective studies should explore the potential causal association between neck pain and MetS and the potential common background factors of neck pain and MetS.</p
Unique Roles of Mothering and Fathering in Child Anxiety; Moderation by Childâs Age and Gender
We examined the associations between the parenting dimensions autonomy granting, over control, and rejection and childrenâs anxiety, in relation to parent and child gender and child age. Elementary school-aged children (n = 179, Mage = 10.27, SD = 1.30), adolescents (n = 127, Mage = 15.02, SD = 1.54) and both their parents completed questionnaires on parenting and childrenâs anxiety. Parenting was more strongly related to child anxiety in elementary school children than in adolescents. Maternal over control was uniquely related to elementary school-aged childrenâs anxiety whereas paternal over control was more important during adolescence. Opposite to our expectations, we found higher levels of parental autonomy granting to be related to higher levels of anxiety for younger elementary school-aged children (age < 10). For adolescents, the association between paternal over control and anxiety was stronger for older adolescents (age > 15), with higher levels of over control related to higher levels of anxiety. For both elementary school-aged children and adolescents, the associations between parenting and child anxiety did not differ as a function of the childâs gender. If we are to understand the associations between parenting and childrenâs anxiety, it is important to distinguish parental autonomy granting from parental over control and to consider the role of parent gender and the age of the child
Magnetization transfer imaging in âpremanifestâ Huntingtonâs disease
To investigate whether magnetization transfer imaging (MTI) is a useful detector of diffuse brain abnormalities in âpremanifestâ carriers of the Huntingtonâs disease (HD) gene mutation. Furthermore we examined the relations between MTI, clinical measures and CAG repeat length. Sixteen premanifest carriers of the HD gene without motor manifestation and 14 non-carriers underwent a clinical evaluation and a MRI scan. MTI analysis of whole brain, grey matter and white matter was performed producing magnetization transfer ratio (MTR) histograms. A lower peak height of the grey matter MTR histogram in carriers was significantly associated with more UHDRS motor abnormalities. Furthermore, a lower peak height of the whole brain, grey and white matter was strongly associated with a longer CAG repeat length. MTI measures themselves did not differ significantly between carriers and non-carriers. In premanifest HD mutation carriers, a lower MTR peak height, reflecting worse histological brain composition, was related to subtle motor abnormalities and higher CAG repeat length. Although we could not detect altered MTI characteristics in carriers of the HD gene mutation without clinical manifestations, we did provide evidence that the MTR peak height might reflect genetic and subclinical disease burden and may be of value in monitoring further disease progression and provide insight in clinical heterogeneity
Spectroscopic analysis of finite size effects around a Kondo quantum dot
We consider a simple setup in which a small quantum dot is strongly connected
to a finite size box. This box can be either a metallic box or a finite size
quantum wire.The formation of the Kondo screening cloud in the box strongly
depends on the ratio between the Kondo temperature and the box level spacing.
By weakly connecting two metallic reservoirs to the quantum dot, a detailed
spectroscopic analysis can be performed. Since the transport channels and the
screening channels are almost decoupled, such a setup allows an easier access
to the measure of finite-size effects associated with the finite extension of
the Kondo cloud.Comment: contribution to Les Houches proceeding, ``Quantum magnetism'' 200
Faculty verbal evaluations reveal strategies used to promote medical student performance
Background: Preceptors rarely follow medical students’ developing clinical performance over time and across disciplines. This study analyzes preceptors’ descriptions of longitudinal integrated clerkship (LIC) students’ clinical development and their identification of strategies to guide students’ progress. Methods: We used a common evaluation framework, reporter-interpreter-manager-educator, to guide multidisciplinary LIC preceptors’ discussions of students’ progress. We conducted thematic analysis of transcripts from preceptors’ (seven longitudinal ambulatory preceptors per student) quarterly group discussions of 15 students’ performance over one year. Results: All students’ clinical development progressed, although most experienced obstacles. Lack of structure in the history and physical exam commonly obstructed progression. Preceptors used templates for data gathering, and modeling or experiences in the inpatient setting to provide time and solidify structure. To advance students’ knowledge acquisition, many preceptors identified focused learning topics with their students; to promote application of knowledge, preceptors used reasoning strategies to teach the steps involved in synthesizing clinical data. Preceptors shared accountability for helping students advance as the LIC allowed them to follow students’ response to teaching strategies. Discussion: These results depict preceptors’ perceptions of LIC students’ developmental continuum and illustrate how multidisciplinary preceptors can use a common evaluation framework to identify strategies to improve performance and follow students’ performance longitudinally
Silicon-hydroxyapatite bioactive coatings (Si-HA) from diatomaceous earth and silica. Study of adhesion and proliferation of osteoblast-like cells
The aim of this study consisted on investigating
the influence of silicon substituted hydroxyapatite (SiâHA)
coatings over the human osteoblast-like cell line (SaOS-2)
behaviour. Diatomaceous earth and silica, together with
commercial hydroxyapatite were respectively the silicon
and HA sources used to produce the SiâHA coatings. HA
coatings with 0 wt% of silicon were used as control of the
experiment. Pulsed laser deposition (PLD) was the selected
technique to deposit the coatings. The SiâHA thin films
were characterized by Fourier Transformed Infrared
Spectroscopy (FTIR) demonstrating the efficient transfer of
Si to the HA structure. The in vitro cell culture was
established to assess the cell attachment, proliferation and
osteoblastic activity respectively by, Scanning Electron
Microscopy (SEM), DNA and alkaline phosphatase (ALP)
quantification. The SEM analysis demonstrated a similar
adhesion behaviour of the cells on the tested materials and
the maintenance of the typical osteoblastic morphology
along the time of culture. The SiâHA coatings did not
evidence any type of cytotoxic behaviour when compared
with HA coatings. Moreover, both the proliferation rate
and osteoblastic activity results showed a slightly better
performance on the SiâHA coatings from diatoms than on
the SiâHA from silica.This work was supported by the UE-Interreg IIIA (SP1.P151/03) Proteus project and Xunta de Galicia ( Projects: 2006/12 and PGIDITO5PXIC30301PN)
Static stretching of the hamstring muscle for injury prevention in football codes: a systematic review
Purpose: Hamstring injuries are common among football players. There is still disagreement regarding prevention. The aim of this review is to determine whether static stretching reduces hamstring injuries in football codes.
Methods: A systematic literature search was conducted on the online databases PubMed, PEDro, Cochrane, Web of Science, Bisp and Clinical Trial register. Study results were presented descriptively and the quality of the studies assessed were based on Cochraneâs ârisk of biasâ tool.
Results: The review identified 35 studies, including four analysis studies. These studies show deficiencies in the quality of study designs.
Conclusion: The study protocols are varied in terms of the length of intervention and follow-up. No RCT studies are available, however, RCT studies should be conducted in the near future
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