1,837 research outputs found
Improved localization of seizure onset zones using spatiotemporal constraints and time-varying source connectivity
Presurgical evaluation of brain neural activity is commonly carried out in refractory epilepsy patients to delineate as accurately as possible the seizure onset zone (SOZ) before epilepsy surgery. In practice, any subjective interpretation of electroencephalographic (EEG) recordings is hindered mainly because of the highly stochastic behavior of the epileptic activity. We propose a new method for dynamic source connectivity analysis that aims to accurately localize the seizure onset zones by explicitly including temporal, spectral, and spatial information of the brain neural activity extracted from EEG recordings. In particular, we encode the source nonstationarities in three critical stages of processing: Inverse problem solution, estimation of the time courses extracted from the regions of interest, and connectivity assessment. With the aim to correctly encode all temporal dynamics of the seizure-related neural network, a directed functional connectivity measure is employed to quantify the information flow variations over the time window of interest. Obtained results on simulated and real EEG data confirm that the proposed approach improves the accuracy of SOZ localization
Exploring host genetic polymorphisms involved in SARS-CoV infection autcomes: implications for personalized medicine in COVID-19
Objective. To systematically explore genetic polymorphisms associated with the clinical outcomes in SARS-CoV infection in
humans. Methods. This comprehensive literature search comprised available English papers published in PubMed/Medline and
SCOPUS databases following the PRISMA-P guidelines and PICO/AXIS criteria. Results. Twenty-nine polymorphisms located
in 21 genes were identified as associated with SARS-CoV susceptibility/resistance, disease severity, and clinical outcomes
predominantly in Asian populations. Thus, genes implicated in key pathophysiological processes such as the mechanisms
related to the entry of the virus into the cell and the antiviral immune/inflammatory responses were identified. Conclusions.
Although caution must be taken, the results of this systematic review suggest that multiple genetic polymorphisms are
associated with SARS-CoV infection features by affecting virus pathogenesis and host immune response, which could have
important applications for the study and understanding of genetics in SARS-CoV-2/COVID-19 and for personalized
translational clinical practice depending on the population studied and associated environments
Enhancement of the non-invasive electroenterogram to identify intestinal pacemaker activity
Surface recording of electroenterogram (EEnG) is a non-invasive method for
monitoring intestinal myoelectrical activity. However, surface EEnG is seriously
affected by a variety of interferences: cardiac activity, respiration, very low frequency
components and movement artefacts. The aim of this study is to eliminate respiratory
interference and very low frequency components from external EEnG recording by
means of empirical mode decomposition (EMD), so as to obtain more robust indicators
of intestinal pacemaker activity from external EEnG signal.
For this purpose, 11 recording sessions were performed in an animal model
under fasting conditions and in each individual session the myoelectrical signal was
recorded simultaneously in the intestinal serosa and the external abdominal surface in
physiological states. Various parameters have been proposed for evaluating the efficacy
of the method in reducing interferences: the signal-to-interference ratio (S/I ratio),
attenuation of the target and interference signals, the normal slow wave percentage and
the stability of the dominant frequency (DF) of the signal.
The results show that the S/I ratio of the processed signals is significantly greater
than the original values (9.66±4.44 dB vs. 1.23±5.13 dB), while the target signal was
barely attenuated (-0.63±1.02 dB). The application of the EMD method also increased
the percentage of the normal slow wave to 100% in each individual session and enabled
the stability of the DF of the external signal to be increased considerably. Furthermore,
the variation coefficient of the DF derived from the external processed signals is
comparable to the coefficient obtained using internal recordings. Therefore the EMD
method could be a very useful tool to improve the quality of external EEnG recording in
the low frequency range, and therefore to obtain more robust indicators of the intestinal
pacemaker activity from non invasive EEnG recordingsThe authors would like to thank D Alvarez-Martinez, Dr C Vila and the Veterinary Unit of the Research Centre of 'La Fe' University Hospital (Valencia, Spain), where the surgical interventions and recording sessions were carried out, and the R+D+I Linguistic Assistance Office at the UPV for their help in revising this paper. This research study was sponsored by the Ministerio de Ciencia y Tecnologia de Espana (TEC2007-64278) and by the Universidad Politecnica de Valencia, as part of a UPV research and development Grant Programme.Ye Lin, Y.; Garcia Casado, FJ.; Prats Boluda, G.; Ponce, JL.; Martínez De Juan, JL. (2009). Enhancement of the non-invasive electroenterogram to identify intestinal pacemaker activity. PHYSIOLOGICAL MEASUREMENT. 30(9):885-902. https://doi.org/10.1088/0967-3334/30/9/002S885902309Amaris, M. A., Sanmiguel, C. P., Sadowski, D. C., Bowes, K. L., & Mintchev, M. P. (2002). Digestive Diseases and Sciences, 47(11), 2480-2485. doi:10.1023/a:1020503908304Bass, P., & Wiley, J. N. (1965). Electrical and extraluminal contractile-force activity of the duodenum of the dog. The American Journal of Digestive Diseases, 10(3), 183-200. doi:10.1007/bf02233747Bradshaw, L. A., Allos, S. H., Wikswo, J. P., & Richards, W. O. (1997). Correlation and comparison of magnetic and electric detection of small intestinal electrical activity. American Journal of Physiology-Gastrointestinal and Liver Physiology, 272(5), G1159-G1167. doi:10.1152/ajpgi.1997.272.5.g1159Camilleri, M., Hasler, W. L., Parkman, H. P., Quigley, E. M. M., & Soffer, E. (1998). Measurement of gastrointestinal motility in the GI laboratory. Gastroenterology, 115(3), 747-762. doi:10.1016/s0016-5085(98)70155-6Chen, J. D. Z., & Lin, Z. (1993). Adaptive cancellation of the respiratory artifact in surface recording of small intestinal electrical activity. Computers in Biology and Medicine, 23(6), 497-509. doi:10.1016/0010-4825(93)90097-kChen, J., & McCallum, R. W. (1991). Electrogastrography: measuremnt, analysis and prospective applications. Medical & Biological Engineering & Computing, 29(4), 339-350. doi:10.1007/bf02441653Chen, J. D. Z., Schirmer, B. D., & McCallum, R. W. (1993). Measurement of electrical activity of the human small intestine using surface electrodes. IEEE Transactions on Biomedical Engineering, 40(6), 598-602. doi:10.1109/10.237682Garcia-Casado, J., Martinez-de-Juan, J. L., & Ponce, J. L. (2005). Noninvasive Measurement and Analysis of Intestinal Myoelectrical Activity Using Surface Electrodes. IEEE Transactions on Biomedical Engineering, 52(6), 983-991. doi:10.1109/tbme.2005.846730Gordon, A. D. (1987). A Review of Hierarchical Classification. Journal of the Royal Statistical Society. Series A (General), 150(2), 119. doi:10.2307/2981629Huang, N. E., Shen, Z., Long, S. R., Wu, M. C., Shih, H. H., Zheng, Q., … Liu, H. H. (1998). The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 454(1971), 903-995. doi:10.1098/rspa.1998.0193Irimia, A., & Bradshaw, L. A. (2005). Artifact reduction in magnetogastrography using fast independent component analysis. Physiological Measurement, 26(6), 1059-1073. doi:10.1088/0967-3334/26/6/015Lammers, W. J. E. P., & Stephen, B. (2008). Origin and propagation of individual slow waves along the intact feline small intestine. Experimental Physiology, 93(3), 334-346. doi:10.1113/expphysiol.2007.039180Liang, H. (2001). Adaptive independent component analysis of multichannel electrogastrograms. Medical Engineering & Physics, 23(2), 91-97. doi:10.1016/s1350-4533(01)00019-4Liang, J., Cheung, J. Y., & Chen, J. D. Z. (1997). Detection and deletion of motion artifacts in electrogastrogram using feature analysis and neural networks. Annals of Biomedical Engineering, 25(5), 850-857. doi:10.1007/bf02684169Liang, H., Lin, Z., & McCallum, R. W. (2000). Artifact reduction in electrogastrogram based on empirical mode decomposition method. Medical & Biological Engineering & Computing, 38(1), 35-41. doi:10.1007/bf02344686Zhi-Yue Lin, Chen, Z., & Jian De. (1994). Time-frequency representation of the electrogastrogram-application of the exponential distribution. IEEE Transactions on Biomedical Engineering, 41(3), 267-275. doi:10.1109/10.284945Lin, Z. Y., & Chen, J. D. Z. (1994). Recursive running DCT algorithm and its application in adaptive filtering of surface electrical recording of small intestine. Medical & Biological Engineering & Computing, 32(3), 317-322. doi:10.1007/bf02512529Lin, Z., & Chen, J. D. Z. (1995). Comparison of three running spectral analysis methods for electrogastrographic signals. Medical & Biological Engineering & Computing, 33(4), 596-604. doi:10.1007/bf02522520Maestri, R., Pinna, G. D., Porta, A., Balocchi, R., Sassi, R., Signorini, M. G., … Raczak, G. (2007). Assessing nonlinear properties of heart rate variability from short-term recordings: are these measurements reliable? Physiological Measurement, 28(9), 1067-1077. doi:10.1088/0967-3334/28/9/008Martinez-de-Juan, J. ., Saiz, J., Meseguer, M., & Ponce, J. . (2000). Small bowel motility: relationship between smooth muscle contraction and electroenterogram signal. Medical Engineering & Physics, 22(3), 189-199. doi:10.1016/s1350-4533(00)00032-1Mintchev, M. P., Kingma, Y. J., & Bowes, K. L. (1993). Accuracy of cutaneous recordings of gastric electrical activity. Gastroenterology, 104(5), 1273-1280. doi:10.1016/0016-5085(93)90334-9Prats-Boluda, G., Garcia-Casado, J., Martinez-de-Juan, J. L., & Ponce, J. L. (2007). Identification of the slow wave component of the electroenterogram from Laplacian abdominal surface recordings in humans. Physiological Measurement, 28(9), 1115-1133. doi:10.1088/0967-3334/28/9/012Quigley, E. M. M. (1996). GASTRIC AND SMALL INTESTINAL MOTILITY IN HEALTH AND DISEASE. Gastroenterology Clinics of North America, 25(1), 113-145. doi:10.1016/s0889-8553(05)70368-xSeidel, S. A., Bradshaw, L. A., Ladipo, J. K., Wikswo, J. P., & Richards, W. O. (1999). Noninvasive detection of ischemic bowel. Journal of Vascular Surgery, 30(2), 309-319. doi:10.1016/s0741-5214(99)70142-4Tomomasa, T., Morikawa, A., Sandler, R. H., Mansy, H. A., Koneko, H., Masahiko, T., … Itoh, Z. (1999). Gastrointestinal Sounds and Migrating Motor Complex in Fasted Humans. American Journal of Gastroenterology, 94(2), 374-381. doi:10.1111/j.1572-0241.1999.00862.xWang, Z. S., Cheung, J. Y., & Chen, J. D. Z. (1999). Blind separation of multichannel electrogastrograms using independent component analysis based on a neural network. Medical & Biological Engineering & Computing, 37(1), 80-86. doi:10.1007/bf0251327
Incidence and risk factors for acute gastroenteritis among pilgrims following the French way to Santiago de Compostela (Spain) in summer 2008.
[ES] Conocer la incidencia de gastroenteritis aguda en los peregrinos del Camino de Santiago, los factores de riesgo asociados y su caracterización microbiológica.
Se diseñaron dos estudios simultáneos, uno transversal mediante encuestas autocumplimentadas de peregrinos llegados a Santiago y otro de casos y controles a los peregrinos en el camino. Se hizo un análisis multivariado mediante regresión logística.
En el estudio transversal la densidad de incidencia fue de 23,5 episodios de gastroenteritis aguda por 1.000 peregrinos-día (intervalo de confianza del 95% [IC95%]: 18,9–29,4/103). En el estudio de casos y controles los factores de mayor riesgo fueron la edad <20 años (odds ratio [OR]=4,72; IC95%: 2,16–10,28), viajar en grupo (tres personas o más) (OR=1,49; IC95%: 0,98–2,28) y consumir agua no embotellada (OR=2,09; IC95%: 0,91–4,82). Norovirus fue el microorganismo aislado con más frecuencia (56%).
Ser peregrino menor de 20 años, realizar el camino en grupo y consumir agua no embotellada se asocian con un mayor riesgo de presentar gastroenteritis aguda.
[EN] To determine the incidence of acute gastroenteritis in pilgrims on St. James' Way, as well as associated risk factors and microbiological characteristics.
Two studies were designed simultaneously: a cross-sectional study through self-completed questionnaires among pilgrims reaching Santiago, and a case-control study of pilgrims traveling along the Way. Multivariate analysis was performed using logistic regression.
In the cross-sectional study, the incidence rate was 23.5 episodes of acute gastroenteritis/10³ pilgrims-day (95% CI: 18.9-2.4/10³. In the case-control study, the major risk factors were age <20 years (OR=4.72; 95% CI: 2.16-10.28), traveling in groups (three or more) (OR=1.49; 95% CI: 0.98-2.28), and drinking unbottled water (OR=2.09; 95% CI: 0.91-4.82). The most frequent etiologic agent was norovirus (56%).
Age less than 20 years, traveling in groups and drinking unbottled water were important risk factors for acute gastroenteritis.Para desarrollar el trabajo de campo, el Centro Nacional de Epidemiología (Instituto de Salud Carlos III) financió el desplazamiento y las dietas de los miembros del PEAC, la Consellería de Sanidade de Galicia aportó el material técnico necesario y cedió un vehículo para los desplazamientos a lo largo del Camino, y S.A. de Xestion do Xacobeo facilitó el alojamiento de los investigadores de campo.S
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
The genetic ancestry of American Creole cattle inferred from uniparental and autosomal genetic markers
Cattle imported from the Iberian Peninsula spread throughout America in the early years of discovery and colonization to originate Creole breeds, which adapted to a wide diversity of environments and later received influences from other origins, including zebu cattle in more recent years. We analyzed uniparental genetic markers and autosomal microsatellites in DNA samples from 114 cattle breeds distributed worldwide, including 40 Creole breeds representing the whole American continent, and samples from the Iberian Peninsula, British islands, Continental Europe, Africa and American zebu. We show that Creole breeds differ considerably from each other, and most have their own identity or group with others from neighboring regions. Results with mtDNA indicate that T1c-lineages are rare in Iberia but common in Africa and are well represented in Creoles from Brazil and Colombia, lending support to a direct African influence on Creoles. This is reinforced by the sharing of a unique Y-haplotype between cattle from Mozambique and Creoles from Argentina. Autosomal microsatellites indicate that Creoles occupy an intermediate position between African and European breeds, and some Creoles show a clear Iberian signature. Our results confirm the mixed ancestry of American Creole cattle and the role that African cattle have played in their development
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