This study, which is a part of the initiative 'Lifting The Burden: The Global Campaign to Reduce the Burden of Headache Worldwide', assesses and presents all existing evidence of the world prevalence ...and burden of headache disorders. Population-based studies applying International Headache Society criteria for migraine and tension-type headache, and also studies on headache in general and 'chronic daily headache', have been included. Globally, the percentages of the adult population with an active headache disorder are 46% for headache in general, 11% for migraine, 42% for tension-type headache and 3% for chronic daily headache. Our calculations indicate that the disability attributable to tension-type headache is larger worldwide than that due to migraine. On the World Health Organization's ranking of causes of disability, this would bring headache disorders into the 10 most disabling conditions for the two genders, and into the five most disabling for women.
The rapid growth of data in water resources has created new opportunities to accelerate knowledge discovery with the use of advanced deep learning tools. Hybrid models that integrate theory with ...state‐of‐the art empirical techniques have the potential to improve predictions while remaining true to physical laws. This paper evaluates the Process‐Guided Deep Learning (PGDL) hybrid modeling framework with a use‐case of predicting depth‐specific lake water temperatures. The PGDL model has three primary components: a deep learning model with temporal awareness (long short‐term memory recurrence), theory‐based feedback (model penalties for violating conversation of energy), and model pretraining to initialize the network with synthetic data (water temperature predictions from a process‐based model). In situ water temperatures were used to train the PGDL model, a deep learning (DL) model, and a process‐based (PB) model. Model performance was evaluated in various conditions, including when training data were sparse and when predictions were made outside of the range in the training data set. The PGDL model performance (as measured by root‐mean‐square error (RMSE)) was superior to DL and PB for two detailed study lakes, but only when pretraining data included greater variability than the training period. The PGDL model also performed well when extended to 68 lakes, with a median RMSE of 1.65 °C during the test period (DL: 1.78 °C, PB: 2.03 °C; in a small number of lakes PB or DL models were more accurate). This case‐study demonstrates that integrating scientific knowledge into deep learning tools shows promise for improving predictions of many important environmental variables.
Key Points
Process‐Guided Deep Learning (PGDL) models integrate advanced empirical techniques with process knowledge
We used PGDL to accurately predict lake water temperatures for various conditions
PGDL performance improved significantly when pretraining data included diverse conditions generated by an existing process‐based model
Epidemiology of headache in Europe Stovner, L. J.; Zwart, J.-A.; Hagen, K. ...
European journal of neurology,
April 2006, Letnik:
13, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The present review of epidemiologic studies on migraine and headache in Europe is part of a larger initiative by the European Brain Council to estimate the costs incurred because of brain disorders. ...Summarizing the data on 1‐year prevalence, the proportion of adults in Europe reporting headache was 51%, migraine 14%, and ‘chronic headache’ (i.e. ≥15 days/month or ‘daily’) 4%. Generally, migraine, and to a lesser degree headache, are most prevalent during the most productive years of adulthood, from age 20 to 50 years. Several European studies document the negative influence of headache disorders on the quality of life, and health‐economic studies indicate that 15% of adults were absent from work during the last year because of headache. Very few studies have been performed in Eastern Europe, and there are also surprisingly little data on tension‐type headache from any country. Although the methodology and the quality of the published studies vary considerably, making direct comparisons between different countries difficult, the present review clearly demonstrates that headache disorders are extremely prevalent and have a vast impact on public health. The data collected should be used as arguments to increase resources to headache research and care for headache patients all over the continent.
Cortical activity during periods of rest is punctuated by widespread, synchronous events in both electrophysiological and hemodynamic signals, but their behavioral relevance remains unclear. Here we ...report that these events correspond to momentary drops in cortical arousal and are associated with activity changes in the basal forebrain and thalamus. Combining fMRI and electrophysiology in macaques, we first establish that fMRI transients co-occur with spectral shifts in local field potentials (LFPs) toward low frequencies. Applying this knowledge to fMRI data from the human connectome project, we find that the fMRI transients are strongest in sensory cortices. Surprisingly, the positive cortical transients occur together with negative transients in focal subcortical areas known to be involved with arousal regulation, most notably the basal forebrain. This subcortical involvement, combined with the prototypical pattern of LFP spectral shifts, suggests that commonly observed widespread variations in fMRI cortical activity are associated with momentary drops in arousal.
To examine the relationship between recurrent headache disorders (i.e., migraine and tension-type headache) and lifestyle factors (overweight, low physical activity, and smoking) in an unselected ...population study among adolescents.
In this cross-sectional study from Norway, a total of 5,847 students were interviewed about headache complaints and completed a comprehensive questionnaire including items concerning physical activity and smoking. In addition, they underwent a clinical examination with height and weight measurements. Adolescents with high physical activity who were not current smokers and not overweight were classified as having a good lifestyle status. These students were compared to those with 1 or more of the negative lifestyle factors present in regard to headache diagnosis and headache frequency.
In adjusted multivariate analyses, recurrent headache was associated with overweight (odds ratio OR = 1.4, 95% confidence interval CI 1.2-1.6, p < 0.0001), low physical activity (OR = 1.2, 95% CI 1.1-1.4, p = 0.002), and smoking (OR = 1.5, 95% CI 1.3-1.7, p < 0.0001). The prevalence of OR increased with more than 1 negative lifestyle factor present, evident for headache diagnoses and frequency.
The results from the present study show that overweight, smoking, or low physical activity are independently and in combination associated with recurrent headache among adolescents. The associations observed and the additive effect of these negative lifestyle factors on the prevalence of recurrent headache indicates possible targets for preventive measures.
Hip and knee osteoarthritis (OA) are leading causes of global disability. Most research to date has focused on the knee, with results often extrapolated to the hip, and this extends to treatment ...recommendations in clinical guidelines. Extrapolating results from research on knee OA may limit our understanding of disease characteristics specific to hip OA, thereby constraining development and implementation of effective treatments. This review highlights differences between hip and knee OA with respect to prevalence, prognosis, epigenetics, pathophysiology, anatomical and biomechanical factors, clinical presentation, pain and non-surgical treatment recommendations and management.
Purpose
Accelerate multislice 2D MRI by using RF pulses that simultaneously act on different slices to combine contrast preparation and image acquisition.
Theory and Methods
MRI applications often ...require the use of multiple RF pulses to generate desired contrast and prepare the signal for readout. Examples are the use of inversion prepulses to generate T1 contrast, or the use of spin‐echo preparations to generate T2 or diffusion contrast. In multislice MRI, this separation of contrast preparation and readout can render scans time‐inefficient and lengthy. We introduce a class of pulse sequences that overcomes this inefficiency by combining contrast preparation and signal readout. This is accomplished by using RF pulses that manipulate the magnetization of multiple slices simultaneously and a gradient crusher scheme that selects a target slice for readout.
Results
Feasibility of the method was demonstrated for spin echo–based measurement of water diffusion and tissue pulsation in human brain at 3 T. Increases in time‐efficiency and reductions in scan time were highly dependent on specific implementation and reached as high as 25% and 53%, respectively.
Conclusion
A novel approach to multislice MRI is demonstrated that reduces scan time for specific applications.
Purpose
To demonstrate a practical implementation of an eight‐channel parallel‐transmit system for brain imaging at 7 T based on on‐coil amplifier technology.
Methods
An eight‐channel parallel ...transmit‐receive system was built with optimized on‐coil switch‐mode current RF power amplifiers. The amplifiers were optically controlled from an eight‐channel interface that was connected to a 7 T MRI scanner. The interface also optically received a down‐converted version of the coil current sensed in each amplifier for monitoring and feedback adjustments.
Results
Each on‐coil amplifier delivered more than 100 W peak power and provided enough amplifier decoupling (<−15 dB) for the implemented eight‐channel array configuration. Phantom and human images were acquired to demonstrate practical operation of this new technology in a 7 T MRI scanner.
Conclusion
Further development and improvement of previously demonstrated on‐coil technology led to successful implementation of an eight‐channel parallel‐transmit system able to deliver strong B1 fields for typical brain imaging applications. This is an important step forward toward implementation of on‐coil RF amplification for high‐field MRI.
MRI at high field can be sensitized to the magnetic properties of tissues, which introduces a signal dependence on the orientation of white matter (WM) fiber bundles relative to the magnetic field. ...In addition, study of the NMR relaxation properties of this signal has indicated contributions from compartmentalized water environments inside and outside the myelin sheath that may be separable. Here we further investigated the effects of water compartmentalization on the MRI signal with the goal of extracting compartment-specific information. By comparing MRI measurements of human and marmoset brain at 7T with magnetic field modeling, we show that: (1) water between the myelin lipid bilayers, in the axonal, and in the interstitial space each experience characteristic magnetic field effects that depend on fiber orientation (2) these field effects result in characteristic relaxation properties and frequency shifts for these compartments; and (3) compartmental contributions may be separated by multi-component fitting of the MRI signal relaxation (i.e. decay) curve. We further show the potential application of these findings to the direct mapping of myelin content and assessment of WM fiber integrity with high field MRI.
•Susceptibility contrast in cerebral white matter shows three T2⁎ relaxation components.•Field modeling suggests these components originate from distinct water environments.•Myelin, axonal, and interstitial water each experience characteristic magnetic fields.•Their contributions may be separated by multi-component fitting of the decay curve.
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