Statistical Non-Parametric Mapping in Sensor Space

Michael Wagner,Reyko Tech,Manfred Fuchs,Jo¨rn Kastner,Fernando Gasca 대한의용생체공학회 2017 Biomedical Engineering Letters (BMEL) Vol.7 No.3

Establishing the significance of observed effectsis a preliminary requirement for any meaningful interpretationof clinical and experimental Electroencephalographyor Magnetoencephalography (MEG) data. We propose amethod to evaluate significance on the level of sensorswhilst retaining full temporal or spectral resolution. Inputdata are multiple realizations of sensor data. In this context,multiple realizations may be the individual epochs obtainedin an evoked-response experiment, or group study data,possibly averaged within subject and event type, or spontaneousevents such as spikes of different types. In thiscontribution, we apply Statistical non-Parametric Mapping(SnPM) to MEG sensor data. SnPM is a non-parametricpermutation or randomization test that is assumption-freeregarding distributional properties of the underlying data. The method, referred to as Maps SnPM, is demonstratedusing MEG data from an auditory mismatch negativityparadigm with one frequent and two rare stimuli and validatedby comparison with Topographic Analysis of Variance(TANOVA). The result is a time- or frequencyresolvedbreakdown of sensors that show consistentactivity within and/or differ significantly between event orspike types. TANOVA and Maps SnPM were applied tothe individual epochs obtained in an evoked-responseexperiment. The TANOVA analysis established dataplausibility and identified latencies-of-interest for furtheranalysis. Maps SnPM, in addition to the above, identifiedsensors of significantly different activity between stimulustypes.

Anterior Choroidal Artery Aneurysms: Influence of Regional Microsurgical Anatomy on Safety of Endovascular Treatment

Michael George Zaki Ghali,Visish M. Srinivasan,Kathryn M. Wagner,Sandi Lam,Jeremiah N. Johnson,Peter Kan 대한뇌혈관외과학회 2018 Journal of Cerebrovascular and Endovascular Neuros Vol.20 No.1

Several anatomical variables critically influence therapeutic strategizing for anterior choroidal artery (AChA) aneurysms, and specifically, the safety of flow diversion for these lesions. We review the microsurgical anatomy of the AChA, discussing and detailing these considerations in the treatment of AChA aneurysms, theoretically and in the light of our recent findings.

Imaging Neuror eceptors in the Living Human Brain

Wagner, Henry N.,Dannals, Robert F.,Frost, J. James,Wong, Dean F.,Ravert, Hayden T.,Wilson, Alan A.,Links, Jonathan M.,Burns, H. Donald,Kuhar, Michael J.,Snyder, Solomon H. 대한핵의학회 1984 핵의학 분자영상 Vol.18 No.2

Hemoglobin Andrew-Minneapolis: Hemolytic Erythrocytosis and Severe Iron Overload in Toxic Liver Cirrhosis

Berndt Zur,Birgit Stoffel-Wagner,Michael Ludwig 대한진단검사의학회 2012 Annals of Laboratory Medicine Vol.32 No.6

We report this case involving a 50-yr-old man of Central European descent who presented at our outpatient department with psoriasis. The known preexisting conditions in this case included alcohol-related toxic liver cirrhosis and untreated type 2 diabetes. The patient had an HbA1c level of 6.2%, which was determined during a routine diabetic monitoring visit. We also assessed HbA1c levels via HPLC (Variant; Bio-Rad, Hercules, CA, USA) and noted an anomaly in the HbA fraction. Subsequent chromatographic, electrophoretic, and genetic examinations confirmed Hb Andrew-Minneapolis, a rare genetic Hb anomaly. always been present in this patient, yet the possible causes of its occurrence had not been investigated. On analysis of the patient’s Hb on HPLC, we found an obvious peak of 39.1%. Distinct bands were also noted in the acidic and alkaline hemoglobin electrophoresis (Hydrasys; Sebia, Norcross, GA, USA) results. Capillary zone electrophoresis (Capillarys; Sebia, Norcross, GA,USA) showed an obvious peak of 24.9%. Hemogram analyses (XE-5000; Sysmex, Kobe, Japan) on EDTA-anticoagulated blood (Hb=18.3 g/dL, reference range: 13.5-17.2 g/dL) revealed hyperchromia, macrocytosis (mean corpuscular Hb=37 pg/cell, refernce range: 27-33.5 pg/cell; mean corpuscular volume=103 fL, reference range: 80-99 fL) and reticulocytosis (2.8%, reference range: 0.5-2.0%). Arterial blood gas analysis (Rapidlab 1265; Siemens, Munich, Germany) revealed that the partial pressure of oxygen was 68.5mmHg, slightly lower than the reference range of 70-100 mmHg. The p50 value also decreased, measuring 19 mmHg (reference value: >27 mmHg). Serum sample analysis (Dimension Vista 1500; Siemens, Munich, Germany) indicated that hemolysis (free Hb=386 mg/L, reference value: ≤50 mg/L) was occurring, and the patient had a reduced haptoglobin level of 0.17 g/L (reference range: 0.3-2 g/L). Additionally, the ferritin level distinctly increased to 1,206 ng/mL (reference range: 13-252 ng/mL) and was accompanied by 100% transferrin saturation (reference level: ≤45%). The soluble transferrin receptor level also increased to 1.92 mg/L (reference value: 0.83-1.76 mg/L). Hemochromatosis was excluded via PCR (Lightcycler; Roche, Basel, Switzerland). Gamma-glutamyltransferase (γ-GT), ALT, and AST levels were all slightly elevated. Scleral icterus was visible and the total bilirubin level was 8.3 mg/dL (reference range: 0.2-1.0 mg/dL). Vitamin B12 and folic acid deficiencies were ruled out. Gene sequencing (Applied Biosystems, Carlsbad, CA, USA) revealed the presence of a beta-globin mutation that results in Hb Andrew-Minneapolis [beta 144 (HCl)Lys→Asn]. The polymorphism Hb F-Sardinia [A gamma (E19)Ile→Thr] was also detected. Hb Andrew-Minneapolis is a rare anomaly that results in the formation of a Hb molecule with high oxygen affinity. This results in a left shift of the Hb-oxygen dissociation curve and consecutive erythrocytosis [1]. Only limited reports of falsely high HbA1c levels exist [2, 3]. We suspect that our patient had falsely low HbA1c levels because fasting glucose values were repeatedly >200 mg/dL, and daily blood glucose levels were always pathologically high. The patient presented with hyperchromic macrocytic erythrocytosis with marked hemolysis, indicating an instability of this Hb variant. This anomaly has not been described previously. Likewise, no reports exist substantiating possible iron overload in this variant. Existing liver cirrhosis must obviously be taken into account, as secondary iron overload can occur in alcohol-related toxic liver cirrhosis [4]. However, tranferrin saturation of this high of a level has not been previously described. Misjudgements of the patient’s type 2 diabetes were due to falsely low results of HbA1c levels. Interestingly, only falsely high HbA1c levels have been reported [2, 3]. Hemoglobinopathy with increased oxygen affinity is a rare, yet important, condition in the differential diagnosis of erythrocytosis. To...

MEG and EEG Dipole Clusters from Extended Cortical Sources

Manfred Fuchs,Jo¨rn Kastner,Reyko Tech,Michael Wagner,Fernando Gasca 대한의용생체공학회 2017 Biomedical Engineering Letters (BMEL) Vol.7 No.3

Data from magnetoencephalography (MEG) andelectroencephalography (EEG) suffer from a rather limitedsignal-to-noise-ratio (SNR) due to cortical backgroundactivities and other artifacts. In order to study the effect ofthe SNR on the size and distribution of dipole clustersreconstructed from interictal epileptic spikes, we performedsimulations using realistically shaped volumeconductor models and extended cortical sources with differentsensor configurations. Head models and corticalsurfaces were derived from an averaged magnetic resonanceimage dataset (Montreal Neurological Institute). Extended sources were simulated by spherical patches withGaussian current distributions on the folded cortical surface. Different patch sizes were used to investigate cancellationeffects from opposing walls of sulcal foldings andto estimate corresponding changes in MEG and EEG sensitivitydistributions. Finally, white noise was added to thesimulated fields and equivalent current dipole reconstructionswere performed to determine size and shape of theresulting dipole clusters. Neuronal currents are orientedperpendicular to the local cortical surface and show cancellationeffects of source components on opposing sulcalwalls. Since these mostly tangential aspects from largecortical patches cancel out, large extended sources exhibitmore radial components in the head geometry. This effecthas a larger impact on MEG data as compared to EEG,because in a spherical head model radial currents do notyield any magnetic field. Confidence volumes of singlereconstructed dipoles from simulated data at differentSNRs show a good correlation with the extension ofclusters from repeated dipole reconstructions. Size andshape of dipole clusters reconstructed from extended corticalsources do not only depend on spike and timepointselection, but also strongly on the SNR of the measuredinterictal MEG or EEG data. In a linear approximation thesize of the clusters is proportional to the inverse SNR.

Calibration of ShadowCam

David Carl Humm,Mallory Janet Kinczyk,Scott Michael Brylow,Robert Vernon Wagner,Emerson Jacob Speyerer,Nicholas Michael Estes,Prasun Mahanti,Aaron Kyle Boyd,Mark Southwick Robinson 한국우주과학회 2023 Journal of Astronomy and Space Sciences Vol.40 No.4

ShadowCam is a high-sensitivity, high-resolution imager provided by NASA for the Danuri (KPLO) lunar mission. ShadowCam calibration shows that it is well suited for its purpose, to image permanently shadowed regions (PSRs) that occur near the lunar poles. It is 205 times as sensitive as the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC). The signal to noise ratio (SNR) is greater than 100 over a large part of the dynamic range, and the top of the dynamic range is high enough to accommodate most brighter PSR pixels. The optical performance is good enough to take full advantage of the 1.7 meter/pixel image scale, and calibrated images have uniform response. We describe some instrument artifacts that are amenable to future corrections, making it possible to improve performance further. Stray light control is very challenging for this mission. In many cases, ShadowCam can image shadowed areas with directly illuminated terrain in or near the field of view (FOV). We include thorough qualitative descriptions of circumstances under which lunar brightness levels far higher than the top of the dynamic range cause detector or stray light artifacts and the size and extent of the artifact signal under those circumstances.

Global-scale assessment and combination of SMAP with ASCAT (active) and AMSR2 (passive) soil moisture products

Kim, Hyunglok,Parinussa, Robert,Konings, Alexandra G.,Wagner, Wolfgang,Cosh, Michael H.,Lakshmi, Venkat,Zohaib, Muhammad,Choi, Minha Elsevier 2018 Remote sensing of environment Vol.204 No.-

<P><B>Abstract</B></P> <P>Global-scale surface soil moisture (SSM) products retrieved from active and passive microwave remote sensing provide an effective method for monitoring near-real-time SSM content with nearly daily temporal resolution. In the present study, we first inter-compared global-scale error patterns and combined the Soil Moisture Active Passive (SMAP), Advanced Scatterometer (ASCAT), and Advanced Microwave Scanning Radiometer 2 (AMSR2) SSM products using a triple collocation (TC) analysis and the maximized Pearson correlation coefficient (R) method from April 2015 to December 2016. The Global Land Data Assimilation System (GLDAS) and global <I>in situ</I> observations were utilized to investigate and to compare the quality of satellite-based SSM products.</P> <P>The average R-values of SMAP, ASCAT, and AMSR2 were 0.74, 0.64, and 0.65 when they compared with <I>in situ</I> networks, respectively. The ubRMSD values were (0.0411, 0.0625, and 0.0708) m<SUP>3</SUP> m<SUP>−3</SUP>; and the bias values were (−0.0460, 0.0010, and 0.0418) m<SUP>3</SUP> m<SUP>−3</SUP> for SMAP, ASCAT, and AMSR2, respectively. The highest average R-values from SMAP against the <I>in situ</I> results are very encouraging; only SMAP showed higher R-values than GLDAS in several <I>in situ</I> networks with low ubRMSD (0.0438m<SUP>3</SUP> m<SUP>−3</SUP>). Overall, SMAP showed a dry bias (−0.0460m<SUP>3</SUP> m<SUP>−3</SUP>) and AMSR2 had a wet bias (0.0418m<SUP>3</SUP> m<SUP>−3</SUP>); while ASCAT showed the least bias (0.0010m<SUP>3</SUP> m<SUP>−3</SUP>) among all the products.</P> <P>Each product was evaluated using TC metrics with respect to the different ranges of vegetation optical depth (VOD). Under vegetation scarce conditions (VOD<0.10), such as desert and semi-desert regions, all products have difficulty obtaining SSM information. In regions with moderately vegetated areas (0.10<VOD<0.40), SMAP showed the highest Signal-to-Noise Ratio. Over highly vegetated regions (VOD>0.40) ASCAT showed comparatively better performance than did the other products.</P> <P>Using the maximized R method, SMAP, ASCAT, and AMSR2 products were combined one by one using the GLDAS dataset for reference SSM values. When the satellite products were combined, R-values of the combined products were improved or degraded depending on the VOD ranges produced, when compared with the results from the original products alone.</P> <P>The results of this study provide an overview of SMAP, ASCAT, and AMSR2 reliability and the performance of their combined products on a global scale. This study is the first to show the advantages of the recently available SMAP dataset for effective merging of different satellite products and of their application to various hydro-meteorological problems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SMAP strongly agreed with the temporal dynamics of <I>in-situ</I> observations. </LI> <LI> All remotely sensed soil moisture products were sound over moderately vegetated areas. </LI> <LI> Over densely vegetated areas, ASCAT performed better than the other products. </LI> <LI> The maximized R method was utilized to show the importance of individual datasets. </LI> <LI> The SMAP-ASCAT combination performed better than the other combined products. </LI> </UL> </P>

특집 : 퇴계학보 드디어 50집 ; 본지 창립 50집 기념호에 보내는 국내외 축사

서원섭,우야정일,강전무언,주하,구기성,Michael C . Kalton,Gerhart Schmidt,Edward W . Wagner 퇴계학연구원 1986 退溪學報 Vol.50 No.1

The Architecture of the Multisubunit TRAPP I Complex Suggests a Model for Vesicle Tethering

Kim, Yeon-Gil,Raunser, Stefan,Munger, Christine,Wagner, John,Song, Young-Lan,Cygler, Miroslaw,Walz, Thomas,Oh, Byung-Ha,Sacher, Michael Elsevier 2006 Cell Vol.127 No.4

<P><B>Summary</B></P><P>Transport protein particle (TRAPP) I is a multisubunit vesicle tethering factor composed of seven subunits involved in ER-to-Golgi trafficking. The functional mechanism of the complex and how the subunits interact to form a functional unit are unknown. Here, we have used a multidisciplinary approach that includes X-ray crystallography, electron microscopy, biochemistry, and yeast genetics to elucidate the architecture of TRAPP I. The complex is organized through lateral juxtaposition of the subunits into a flat and elongated particle. We have also localized the site of guanine nucleotide exchange activity to a highly conserved surface encompassing several subunits. We propose that TRAPP I attaches to Golgi membranes with its large flat surface containing many highly conserved residues and forms a platform for protein-protein interactions. This study provides the most comprehensive view of a multisubunit vesicle tethering complex to date, based on which a model for the function of this complex, involving Rab1-GTP and long, coiled-coil tethers, is presented.</P>

Preliminary Characterization of Secondary Illumination at Shackleton Crater Permanently Shadowed Region from ShadowCam Observations and Modeling

Prasun Mahanti,Mark Southwick Robinson,David Carl Humm,Robert Vernon Wagner,Nicholas Michael Estes,Jean-Pierre Williams 한국우주과학회 2023 Journal of Astronomy and Space Sciences Vol.40 No.4

Lunar permanently shadowed regions (PSRs) never see direct sunlight and are illuminated only by secondary illumination - light reflected from nearby topography. The ShadowCam imaging experiment onboard the Korea Pathfinder Lunar Orbiter is acquiring images of these PSRs. We characterize and discuss the nature of secondary illumination for the Shackleton PSR from ShadowCam radiance-calibrated images. We also use modeling to understand the magnitude and direction of the secondary illumination. Results from our analysis highlight the non-homogeneous, dynamic, and complex nature of PSR secondary lighting. Knowledge of the direction of the secondary illumination is crucial for reli-able interpretation of contrasts observed in ShadowCam images. This preliminary analysis of the floor of Shackleton crater from images acquired over multiple secondary illumination conditions does not reveal indications of exposed surface ice, even though temperatures are constantly below 110K.