349 research outputs found
Theologian by Day, Double Bass Player by Night: Luther on Instruments
In addition to supporting the voice in worship, are there other ways of thinking about the use of instruments in worship? In this session, we will explore Martin Luther\u27s contributions toward a Christological and soteriological understanding of the use of instruments in church. We will do so in conversation with U.S. Hispanic reflections on the Christological understanding of beauty, which stress the link between discipleship and ethics. Some reflections on the role of instrumentalists in worship will follow, including the idea that instrumentalists have challenging roles to play as both theologians and interpreters of culture in today\u27s society. A musical setting on a Hispanic hymn composed by the presenter for devotional purposes will be used to illustrate some of the concepts discussed in the sectional
Flip angle mapping with the accelerated 3D look-locker sequence
Purpose A new approach to mapping the flip angle quickly and efficiently in 3D based on the Look-Locker technique is presented. Methods We modified the accelerated 3D Look-Locker T1 measurement technique to allow rapid measurement of flip angle. By removing the inversion pulses and interleaving two radio frequency pulses with different amplitude, it is possible to fit directly for the true flip angle using a reduced number of parameters. This technique, non-inverted Double Angle Look-Locker, allows quick and efficient mapping of the flip angle in 3D. Results non-inverted Double Angle Look-Locker is validated in vitro against the actual flip angle imaging technique for a range of flip angles and T1 values. Flip angle maps produced with non-inverted Double Angle Look-Locker can be acquired in approximately 1 min, and are accurate to within 10% of the actual flip angle imaging measurement. It is shown to accurately measure the excited slab profile of several different pulses. An application to correcting in vivo DESPOT T1 data is presented. Conclusion The presented technique is a rapid method for mapping flip angles across a 3D volume, capable of producing a flip angle map in approximately 1 min. © 2013 Wiley Periodicals, Inc
Are Scores on the PPT Useful in Determination of Risk of Future Falls in Individuals With Dementia?
Individuals with dementia or Alzheimer’s disease (AD), exhibit both a progressive decline in cognitive function and accumulating difficulty with physical function.1 As cognitive impairment begins, individuals will initially demonstrate difficulties with short-term memory and with instrumental activities of daily living. As the dementia progresses, individuals will increasingly demonstrate difficulties with long-term memory, communication, and basic activities of daily living
MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis.
BACKGROUND AND PURPOSE: The relationship between middle cerebral artery (MCA) flow velocity (CFV) and cerebral blood flow (CBF) is uncertain because of unknown vessel diameter response to physiological stimuli. The purpose of this study was to directly examine the effect of a simulated orthostatic stress (lower body negative pressure [LBNP]) as well as increased or decreased end-tidal carbon dioxide partial pressure (P(ET)CO(2)) on MCA diameter and CFV.
METHODS: Twelve subjects participated in a CO(2) manipulation protocol and/or an LBNP protocol. In the CO(2) manipulation protocol, subjects breathed room air (normocapnia) or 6% inspired CO(2) (hypercapnia), or they hyperventilated to approximately 25 mm Hg P(ET)CO(2) (hypocapnia). In the LBNP protocol, subjects experienced 10 minutes each of -20 and -40 mm Hg lower body suction. CFV and diameter of the MCA were measured by transcranial Doppler and MRI, respectively, during the experimental protocols.
RESULTS: Compared with normocapnia, hypercapnia produced increases in both P(ET)CO(2) (from 36+/-3 to 40+/-4 mm Hg, P
CONCLUSIONS: Under the conditions of this study, changes in MCA diameter were not detected. Therefore, we conclude that relative changes in CFV were representative of changes in CBF during the physiological stimuli of moderate LBNP or changes in P(ET)CO(2)
Modelling environmental influences on calving at Helheim Glacier in eastern Greenland
Calving is an important mass-loss process for many glaciers worldwide, and
has been assumed to respond to a variety of environmental influences. We
present a grounded, flowline tidewater glacier model using a physically-based
calving mechanism, applied to Helheim Glacier, eastern
Greenland. By qualitatively examining both modelled size and frequency of
calving events, and the subsequent dynamic response, the model is found to
realistically reproduce key aspects of observed calving behaviour. Experiments explore four
environmental variables which have been suggested to affect calving rates:
water depth in crevasses, basal water pressure, undercutting of the calving
face by submarine melt and backstress from ice mélange. Of the four
variables, only crevasse water depth and basal water pressure were found to
have a significant effect on terminus behaviour when applied at a realistic
magnitude. These results are in contrast to previous modelling studies, which
have suggested that ocean temperatures could strongly influence the calving
front. The results raise the possibility that Greenland outlet glaciers could
respond to the recent trend of
increased surface melt observed in Greenland more strongly than previously thought, as surface ablation can
strongly affect water depth in crevasses and water pressure at the glacier
bed
Comparing the MRI Appearance of the Lymph Nodes and Spleen in Wild-Type and Immuno-Deficient Mouse Strains
The goal of this study was to investigate the normal MRI appearance of lymphoid organs in immuno-competent and immuno-deficient mice commonly used in research. Four mice from each of four different mouse strains (nude, NOG, C57BL/6, CB-17 SCID (SCID)) were imaged weekly for one month. Images were acquired with a 3D balanced steady state free precession (bSSFP) sequence. The volume of the lymph nodes and spleens were measured from MR images. In images of nude and SCID mice, lymph nodes sometimes contained a hyperintense region visible on MRI images. Volumes of the nodes were highly variable in nude mice. Nodes in SCID mice were smaller than in nude or C57Bl/6 mice (p<0.0001). Lymph node volumes changed slightly over time in all strains. The spleens of C57Bl/6 and nude mice were similar in size and appearance. Spleens of SCID and NOG mice were significantly smaller (p<0.0001) and abnormal in appearance. The MRI appearance of the normal lymph nodes and spleen varies considerably in the various mouse strains examined in this study. This is important to recognize in order to avoid the misinterpretation of MRI findings as abnormal when these strains are used in MRI imaging studies
Substantia Nigra Volume Dissociates Bradykinesia and Rigidity from Tremor in Parkinson’s Disease: A 7 Tesla Imaging Study
Background: In postmortem analysis of late stage Parkinson’s disease (PD) neuronal loss in the substantial nigra (SN) correlates with the antemortem severity of bradykinesia and rigidity, but not tremor.
Objective: To investigate the relationship between midbrain nuclei volume as an in vivo biomarker for surviving neurons in mild-to-moderate patients using 7.0 Tesla MRI.
Methods: We performed ultra-high resolution quantitative susceptibility mapping (QSM) on the midbrain in 32 PD participants with less than 10 years duration and 8 healthy controls. Following blinded manual segmentation, the individual volumes of the SN, subthalamic nucleus, and red nucleus were measured. We then determined the associations between the midbrain nuclei and clinical metrics (age, disease duration, MDS-UPDRS motor score, and subscores for bradykinesia/rigidity, tremor, and postural instability/gait difficulty).
Results: We found that smaller SN correlated with longer disease duration (r = –0.49, p = 0.004), more severe MDS-UPDRS motor score (r = –0.42, p = 0.016), and more severe bradykinesia-rigidity subscore (r = –0.47, p = 0.007), but not tremor or postural instability/gait difficulty subscores. In a hemi-body analysis, bradykinesia-rigidity severity only correlated with SN contralateral to the less-affected hemi-body, and not contralateral to the more-affected hemi-body, possibly reflecting the greatest change in dopamine neuron loss early in disease. Multivariate generalized estimating equation model confirmed that bradykinesia-rigidity severity, age, and disease duration, but not tremor severity, predicted SN volume
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