Simultaneous multislice acquisition using rosette trajectories (SMART): a new imaging method for functional MRI

OBJECTIVES: Despite the recent introduction of new peroral drugs as well as neurosurgical methods for Parkinson's disease, treatment of late stage parkinsonian patients remains difficult and many patients become severely handicapped because of fluctuations in their motor status. Injections and infusions of apomorphine has been suggested as an alternative in the treatment of these patients, but the number of studies describing the effects of such a treatment over longer time periods is still limited. The objective was to investigate the therapeutic response and range of side effects during long term treatment with apomorphine in advanced Parkinson's disease. METHODS: Forty nine patients (30 men, 19 women; age range 42-80 years) with Parkinson's disease were treated for 3 to 66 months with intermittent subcutaneous injections or continuous infusions of apomorphine. RESULTS: Most of the patients experienced a long term symptomatic improvement. The time spent in "off" was significantly reduced from 50 to 29.5% with injections and from 50 to 25% with infusions of apomorphine. The quality of the remaining "off" periods was improved with infusion treatment, but was relatively unaffected by apomorphine injections. The overall frequency and intensity of dyskinesias did not change. The therapeutic effects of apomorphine were stable over time. The most common side effect was local inflammation at the subcutaneous infusion site, whereas the most severe were psychiatric side effects occurring in 44% of the infusion and 12% of the injection treated patients. CONCLUSION: Subcutaneous apomorphine is a highly effective treatment which can substantially improve the symptomatology in patients with advanced stage Parkinson's disease over a prolonged period of time.     

Read-react-respond: An integrative model for understanding sexual revictimization.

Females who have been sexually abused in childhood are at significantly higher risk to be revictimized in adolescence and adulthood. Revictimization is associated with a raft of adverse mental and physical health outcomes, and so understanding why victims of childhood sexual abuse are more vulnerable to later sexual assaults has critical implications for their development. It has been hypothesized that sexual abuse in childhood results in reduced ability to recognize and/or respond effectively to sexual threats later in life, but studies examining these ideas have produced inconsistent results. Further, this research has failed to incorporate the powerful physiological reaction elicited by threats of imminent harm to the self, which has the potential to disrupt cognitive processing and coping behavior. In the present paper, we propose a model of revictimization that integrates contemporary theory and research on the biological stress response with cognitive, affective, and behavioral factors believed to be involved in adaptive responding to sexual threats. The model provides a conceptual guide for understanding why females with a history of sexual abuse are more vulnerable to revictimization and offers ideas for improving prevention programs designed to strengthen females' ability to resist sexual coercion. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Multishot rosette trajectories for spectrally selective MR imaging

In nuclear magnetic resonance, different spectral components often correspond to different chemical species and as such, spectral selectivity can be a valuable tool for diagnostic imaging. In the work presented here, a multishot image acquisition method based upon rosette k-space trajectories has been developed and implemented for spectrally selective magnetic resonance imaging (MRI). Parametric forms for the gradient waveforms and design constraints are derived, and an example multishot gradient design is presented. The spectral behaviour for this imaging method is analyzed in a simulation model. For frequencies that are near to the resonant frequency, this method results in a lower intensity, but undistorted image, while for frequencies that are off-resonance by a large amount, the object is incoherently dephased into noise. A method by which acquisitions are delayed by small amounts is introduced to further reduce the residual intensity for off-resonant signals. An image reconstruction method based on convolution gridding, including a correction method for small amounts of magnetic field inhomogeneity, is implemented. Finally, the spectral selectivity is demonstrated in vivo in a study in which both water and lipid images are generated from a single imaging data set     

Videotex: Anatomy of a failure

Considerable excitement has been generated in Europe and North America in videotex - namely, the concept of electronic access in the home to centrally - located computerized databases containing vast amounts of data. However, the public offering of such services has thus far been unsuccessful in achieving significant penetrations in the residential market.Videotex is examined in this paper to illuminate possible reasons for its failure thus far in the residential marketplace. Comparisons are made with somewhat similar on-line systems for accessing computerized data-bases and for performing transactions and transmitting messages to other people. The final conclusion is that most consumers simply do not have a need nor a desire to access vast computerized data-bases of general information. Videotex or any other similar system that attempts to satisfy consumer needs for information in such a fashion will surely fail.     

Localizing the lexicon for reading aloud:replication of a PET study using fMRI

Functional magnetic resonance imaging (fMRI) was used to investigate the neural basis of written word recognition in two normal subjects. With a 1.5T scanner and temporal surface coil, T2 gradient echo images were obtained while subjects read words aloud. As a control condition, subjects visualized false font strings and said the word "range' each time such a string appeared. These two conditions were presented in an oscillatory pattern, alternating 30 s of each condition for a total of 4 min. Comparison of the two conditions using cross-correlation demonstrated strong activation in both subjects in the left posterior superior temporal gyrus, near the site predicted for the visual input lexicon by Déjerine and recently demonstrated by positron emission tomography.     

Deposition and Suspension of Large,Airborne Particles

The focus of this paper is the experimental determination of size-resolved estimates of both deposition and suspension velocities for large, airborne particles (greater than 10 μm diameter). Measurements of particle dry flux onto the top and bottom surface of a smooth, horizontal, surrogate surface were divided by measurements of the concentration of airborne particles to provide estimates of deposition and suspension velocities in 14 size intervals between 5 and 100 μm diameter. Eddy inertial deposition efficiencies (η_di) were determined as a function of eddy Stokes numbers (Stke) larger than 1 and the results agree with the model of Slinn and Slinn (1980) Slinn, S. A. and Slinn, W. G. N. 1980. Predictions for Particle Deposition on Natural Waters. Atmos. Environ., 14: 1013–1016. [CSA][CROSSREF][Crossref], [Web of Science ®] , [Google Scholar]. The model was used to provide estimates of both the inertial and gravitational components for total upward and downward particle velocities. Experimental results for individual particle size intervals produced highly variable results. Much of this variation can be attributed to experimental errors associated with the nature of the atmospheric experiments and not to problems with the model. Upward large particle suspension velocities are similar in magnitude to downward deposition velocities at higher wind speeds and represent a counteracting process to deposition processes that cannot be ignored for accurate representation of the long-range transport for particles between 5 and 50 μm diameter.     

Dissociating working memory from task difficulty in human prefrontal cortex

A functional magnetic resonance imaging (fMRI) study was conducted to determine whether prefrontal cortex (PFC) increases activity in working memory (WM) tasks as a specific result of the demands placed on WM, or to other processes affected by the greater difficulty of such tasks. Increased activity in dorsolateral PFC (DLPFC) was observed during task conditions that placed demands on active maintenance (long retention interval) relative to control conditions matched for difficulty. Furthermore, the activity was sustained over the entire retention interval and did not increase when task difficulty was manipulated independently of WM requirements. This contrasted with the transient increases in activity observed in the anterior cingulate, and other regions of frontal cortex, in response to increased task difficulty but not WM demands. Thus, this study established a double-dissociation between regions responsive to WM versus task difficulty, indicating a specific involvement of DLPFC and related structures in WM function.     

Preoperative cortical localization with functional MRI for use in stereotactic radiosurgery

Accurate localization of the lesion with respect to functionally significant brain is essential to safe stereotactic radiosurgical dose planning. We report the use of functional MR imaging in 3 patients to identify critical areas of surrounding brain and to provide assistance with dose planning, especially with regard to shaping the peripheral isodose around the lesion. We used a functional MRI system employing a conventional 1.5-tesla MRI unit that can detect decreases in deoxyhemoglobin concentration occurring with performance of specific tasks. Two of the patients had supratentorial arteriovenous malformations and 1 patient had a recurrent parasagittal meningioma. Functional MRI provided information on the location of speech, motor, and sensory cortex in these patients. Radiosurgical dose plans were constructed that kept these cortical areas outside of the 30% isodose curves. We believe that the safety of supratentorial parenchymal radiosurgery will be enhanced by the localization of critical brain regions around the target.     

Relationship between elemental carbon, total carbon, and diesel particulate matter in several underground metal/non-metal mines

Elemental carbon (EC) is currently used as a surrogate for diesel particulate matter (DPM) in underground mines since it can be accurately measured at low concentrations and diesels are the only source of submicrometer EC in underground mines. A disadvantage of using EC as a surrogate for DPM is that the fraction of EC in DPM is a function of various engine parameters and fuel formulations, etc. In order to evaluate how EC predicts DPM in the underground mining atmosphere, measurements of total carbon (TC; representing over 80% of the DPM) and EC were taken away from potential interferences in four underground metal/non-metal mines during actual production. In a controlled atmosphere, DPM mass, TC, and EC measurements were also collected while several different types of vehicles simulated production with and without different types of control technologies. When diesel particulate filters (DPFs) were not used, both studies showed that EC could be used to predict DPM mass or TC. The variability of the data started to increase at TC concentrations below 230 microg/m3 and was high (> +/- 20%) at TC concentrations below 160 microg/m3, probably due to the problem with sampling organic carbon (OC) at these concentrations. It was also discovered that when certain DPFs were used, the relationship between DPM and EC changed at lower DPM concentrations.