3,836 research outputs found
Temperatures in Pigs During 3 T MRI Temperatures, Heart Rates, and Breathing Rates of Pigs During RF Power Deposition in a 3 T (128 MHz) Body Coil
Exposure to radiofrequency (RF) power deposition during magnetic resonance imaging (MRI) induces elevated body-tissue temperatures and may cause changes in heart and breathing rates, disturbing thermoregulation. Eleven temperature sensors were placed in muscle tissue and one sensor in the rectum (measured in 10 cm depth) of 20 free-breathing anesthetized pigs to verify temperature curves during RF exposure. Tissue temperatures and heart and breathing rates were measured before, during, and after RF exposure. Pigs were placed into a 60-cm diameter whole-body resonator of a 3 T MRI system. Nineteen anesthetized pigs were divided into four RF exposure groups: sham (0 W/kg), low-exposure (2.7 W/kg, mean exposure time 56 min), moderate-exposure (4.8 W/kg, mean exposure time 31 min), and high-exposure (4.4 W/kg, mean exposure time 61 min). One pig was exposed to a whole-body specific absorption rate (wbSAR) of 11.4 W/kg (extreme-exposure). Hotspot temperatures, measured by sensor 2, increased by mean 5.0 ± 0.9°C, min 3.9; max 6.3 (low), 7.0 ± 2.3°C, min 4.6; max 9.9 (moderate), and 9.2 ± 4.4°C, min 6.1, max 17.9 (high) compared with 0.3 ± 0.3°C in the sham-exposure group (min 0.1, max 0.6). Four time-temperature curves were identified: sinusoidal, parabolic, plateau, and linear. These curve shapes did not correlate with RF intensity, rectal temperature, breathing rate, or heart rate. In all pigs, rectal temperatures increased (2.1 ± 0.9°C) during and even after RF exposure, while hotspot temperatures decreased after exposure. When rectal temperature increased by 1°C, hotspot temperature increased up to 42.8°C within 37 min (low-exposure) or up to 43.8°C within 24 min (high-exposure). Global wbSAR did not correlate with maximum hotspot. Bioelectromagnetics. 2021;42:37–50
Laser-free pelvic alignment in an online adaptive radiotherapy environment.
The MR-Linac (MRL) provides a novel treatment modality that enables online adaptive treatments, but also creates new challenges for patient positioning in a laser-free environment. The accuracy and duration of prostate patient set-up on the MRL using two different methods for patient alignment was determined to establish standard of practice on the MRL. Differences in set-up accuracy were significant in the longitudinal direction and are accounted for in online plan adaption. Both methods recorded similar set-up times. The vendor recommended alignment method involves less manipulation of the patient and will be adopted as the standard positioning method for prostate and other pelvic patients on the MRL in future
Multivariate Hierarchical Modelling of Household Air Pollution
This is the author accepted manuscript. The final version is available from the Statistical Modelling Society via the link in this recordExposure to household air pollution has been attributed to an estimated 3.8 million deaths per year. A major contributor to this exposure is the reliance on various polluting fuels for cooking by almost half of all households in low and middle-income countries. We present a multivariate hierarchical model for surveys of the proportion of people relying on each fuel type, for the period 1990-2017, addressing several challenges with modelling the data including incomplete surveys and sampling bias.Natural Environment Research Council (NERC)World Health Organizatio
Linear Growth through 12 Years is Weakly but Consistently Associated with Language and Math Achievement Scores at Age 12 Years in 4 Low- or Middle-Income Countries.
BackgroundWhether linear growth through age 12 y is associated with language and math achievement at age 12 y remains unclear.ObjectiveOur objective was to investigate associations of linear growth through age 12 y with reading skill, receptive vocabulary, and mathematics performance at age 12 y in 4 low- or middle-income countries (LMICs).MethodsWe analyzed data from the Young Lives Younger Cohort study in Ethiopia (n = 1275), India (n = 1350), Peru (n = 1402), and Vietnam (n = 1594). Age 1, 5, 8, and 12 y height-for-age z scores (HAZ) were calculated. Language and math achievement at age 12 y was assessed with the use of country-specific adaptations of the Peabody Picture Vocabulary Test, the Early Grades Reading Assessment, and a mathematics test; all test scores were standardized by age within country. We used path analysis to examine associations of HAZ with achievement scores. Twelve models were examined at each age (3 tests across 4 countries).ResultsMean HAZ in each country was <-1.00 at all ages. Overall, linear growth through age 12 y was associated with 0.4-3.4% of the variance in achievement scores. HAZ at 1 y was positively and significantly associated with the test score in 11 of the 12 models. This association was significantly mediated through HAZ at 5, 8, and 12 y in 9 of the models. HAZ at 5, 8, and 12 y was positively and significantly associated with test scores in 8, 8, and 6 models, respectively. These associations were mediated through HAZ at older ages in 6 of the HAZ at 5-y models and in 6 of the HAZ at 8-y models.ConclusionChild relative linear growth between ages 1 and 12 y was weakly but consistently associated with language and math achievement at age 12 y in 4 LMICs
Physical State of Molecular Gas in High Galactic Latitude Translucent Clouds
The rotational transitions of carbon monoxide (CO) are the primary means of
investigating the density and velocity structure of the molecular interstellar
medium. Here we study the lowest four rotational transitions of CO towards
high-latitude translucent molecular clouds (HLCs). We report new observations
of the J = (4-3), (2-1), and (1-0) transitions of CO towards eight
high-latitude clouds. The new observations are combined with data from the
literature to show that the emission from all observed CO transitions is
linearly correlated. This implies that the excitation conditions which lead to
emission in these transitions are uniform throughout the clouds. Observed
13CO/12CO (1-0) integrated intensity ratios are generally much greater than the
expected abundance ratio of the two species, indicating that the regions which
emit 12CO (1-0) radiation are optically thick. We develop a statistical method
to compare the observed line ratios with models of CO excitation and radiative
transfer. This enables us to determine the most likely portion of the physical
parameter space which is compatible with the observations. The model enables us
to rule out CO gas temperatures greater than 30K since the most likely
high-temperature configurations are 1 pc-sized structures aligned along the
line of sight. The most probable solution is a high density and low temperature
(HDLT) solution. The CO cell size is approximately 0.01 pc (2000 AU). These
cells are thus tiny fragments within the 100 times larger CO-emitting extent of
a typical high-latitude cloud. We discuss the physical implications of HDLT
cells, and we suggest ways to test for their existence.Comment: 19 pages, 13 figures, 2 tables, emulateapj To be published in The
Astrophysical Journa
Preparation and preclinical evaluation of humanised A33 immunoconjugates for radioimmunotherapy.
A humanised IgG1/k version of A33 (hA33) has been constructed and expressed with yields up to 700 mg l-1 in mouse myeloma NS0 cells in suspension culture. The equilibrium dissociation constant of hA33 (KD = 1.3 nM) was shown to be equivalent to that of the murine antibody in a cell-binding assay. hA33 labelled with yttrium-90 using the macrocyclic chelator 12N4 (DOTA) was shown to localise very effectively to human colon tumour xenografts in nude mice, with tumour levels increasing as blood concentration fell up to 144 h. A Fab' variant of hA33 with a single hinge thiol group to facilitate chemical cross-linking has also been constructed and expressed with yields of 500 mg l-1. Trimaleimide cross-linkers have been used to produce a trivalent Fab fragment (hA33 TFM) that binds antigen on tumour cells with greater avidity than hA33 IgG. Cross-linkers incorporating 12N4 or 9N3 macrocycles have been used to produce hA33 TFM labelled stably and site specifically with yttrium-90 or indium-111 respectively. These molecules have been used to demonstrate that hA33 TFM is cleared more rapidly than hA33 IgG from the circulation of animals but does not lead to accumulation of these metallic radionuclides in the kidney. 90Y-labelled hA33 TFM therefore appears to be the optimal form of the antibody for radioimmunotherapy of colorectal carcinoma
Recognition without identification, erroneous familiarity, and déjà vu
Déjà vu is characterized by the recognition of a situation concurrent with the awareness that this recognition is inappropriate. Although forms of déjà vu resolve in favor of the inappropriate recognition and therefore have behavioral consequences, typical déjà vu experiences resolve in favor of the awareness that the sensation of recognition is inappropriate. The resultant lack of behavioral modification associated with typical déjà vu means that clinicians and experimenters rely heavily on self-report when observing the experience. In this review, we focus on recent déjà vu research. We consider issues facing neuropsychological, neuroscientific, and cognitive experimental frameworks attempting to explore and experimentally generate the experience. In doing this, we suggest the need for more experimentation and amore cautious interpretation of research findings, particularly as many techniques being used to explore déjà vu are in the early stages of development.PostprintPeer reviewe
The Early Days of Research on Carbonic Anhydrase
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73862/1/j.1749-6632.1984.tb12310.x.pd
Global household energy model: a multivariate hierarchical approach to estimating trends in the use of polluting and clean fuels for cooking
This is the final version. Available on open access from Wiley via the DOI in this recordIn 2017 an estimated 3 billion people used polluting fuels and technologies as their primary cooking solution, with 3.8 million deaths annually attributed to household exposure to the resulting fine particulate matter air pollution. Currently, health burdens are calculated using aggregations of fuel types, e.g. solid fuels, as country-level estimates of the use of specific fuel types, e.g. wood and charcoal, are unavailable. To expand the knowledge base about impacts of household air pollution on health, we develop and implement a Bayesian hierarchical model, based on Generalized Dirichlet Multinomial distributions, that jointly estimates non-linear trends in the use of eight key fuel types, overcoming several data-specific challenges including missing or combined fuel use values. We assess model fit using within-sample predictive analysis and an out-of-sample prediction experiment to evaluate the model's forecasting performance.Natural Environment Research Council (NERC)World Health Organizatio
Reverberation Mapping Measurements of Black Hole Masses in Six Local Seyfert Galaxies
We present the final results from a high sampling rate, multi-month,
spectrophotometric reverberation mapping campaign undertaken to obtain either
new or improved Hbeta reverberation lag measurements for several relatively
low-luminosity AGNs. We have reliably measured thetime delay between variations
in the continuum and Hbeta emission line in six local Seyfert 1 galaxies. These
measurements are used to calculate the mass of the supermassive black hole at
the center of each of these AGNs. We place our results in context to the most
current calibration of the broad-line region (BLR) R-L relationship, where our
results remove outliers and reduce the scatter at the low-luminosity end of
this relationship. We also present velocity-resolved Hbeta time delay
measurements for our complete sample, though the clearest velocity-resolved
kinematic signatures have already been published.Comment: 52 pages (AASTeX: 29 pages of text, 8 tables, 7 figures), accepted
for publication in the Astrophysical Journa
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