Dimensionality reduction and unsupervised learning techniques applied to clinical psychiatric and neuroimaging phenotypes

Unsupervised learning and other multivariate analysis techniques are increasingly recognized in neuropsychiatric research. Here, finite mixture models and random forests were applied to clinical observations of patients with major depression to detect and validate treatment response subgroups. Further, independent component analysis and agglomerative hierarchical clustering were combined to build a brain parcellation solely on structural covariance information of magnetic resonance brain images. Übersetzte Kurzfassung: Unüberwachtes Lernen und andere multivariate Analyseverfahren werden zunehmend auf neuropsychiatrische Fragestellungen angewendet. Finite mixture Modelle wurden auf klinische Skalen von Patienten mit schwerer Depression appliziert, um Therapieantwortklassen zu bilden und mit Random Forests zu validieren. Unabhängigkeitsanalysen und agglomeratives hierarchisches Clustering wurden kombiniert, um die strukturelle Kovarianz von Magnetresonanz­tomographie-Bildern für eine Hirnparzellierung zu nutzen

The physical structure of Tabriz in Shah Tahmasp Safavid’s era based on Matrakçı Miniature

Tabriz, located in Northwestern Iran, is one of the most ancient cities of the country before and after Islam. Until the middle of Shah Tahmasp's reign, the second King of Safavid dynasty 962AH/1555AD, Tabriz was the capital city; and after that, up to the end of the Qajarid dynasty 1194AH/1780AD, it has always been the second most important and unique city in Iran considering the religious, political, and economic standpoints, and consequently the architecture and urbanism. Unfortunately, consecutive earthquakes and wars with the neighboring Ottoman Empire have destroyed the spatial structure of this historical city. Likewise, after three decades, the spatial structure of Tabriz during Safavid era is ambiguous. The only documents related to this era are limited to itineraries and some drawings recorded by tourists. The miniature drawn by Nasuh in 944Ah/1537AD known as Matrakci is the oldest and most important recorded document from Safavid Tabriz because of political- military reasons. It was drawn during the military campaign of Sultan Suleiman, the Ottoman king, to Iran under the reign of Shah Tahmasp I; however, none of the architecture and urbanism researchers has attempted to reread this important historical document. Therefore, the purpose of the present paper is to restitute the physical structure of Dar Al-Saltaneh (24) of Tabriz in Safavid dynasty using historic texts based on Matrakci miniature and other historical documents. For this purpose, the recreation was done on the oldest and most complete historical map of Tabriz drawn in 1297Ah/1880AD named Qarajadagi Dar Al-Saltaneh, so that a fairly accurate picture of Tabriz could be presented in this period. Information was gathered using historical-interpretative method or phenomenological approach and data were analyzed and interpreted using analytical-comparative method. The results of the pictorial modeling showed that the structural system of Tabriz was based on two main centralities. First, the governmental center, located at North of the river, with aggregation of the urban spaces and tombs, and the second, the southern center, located at south of the river, which was considered city center or aggregation of religious and commercial services as well as residential spaces.Publisher's Versio

Plasmon-exciton coupling for signal amplification and biosensing : fundamentals and application

Surface plasmon resonance (SPR) is the collective oscillation of frequency-matched free-space photons and surface electrons at a metal/dielectric interface. Their inherent sensitivity to refractive index changes and ability to couple with exciton species and enhance light-matter interaction make them ideal candidates for low-concentration analyte detection compared to conventional biosensors. The use of metal nanostructures and nanomaterials to excite SPR represents the current state-of-the-art. However, the challenges associated with repeatable synthesis of uniform nanomaterials, complex nanostructure fabrication, low SPR generation efficiency and limited understanding of the mechanism of plasmon-exciton coupling for signal amplification have motivated the search for alternative architectures and procedures. The uniform and repeatable gold nanoslit (NS) and nanoledge (NL) array architectures offers a promising route towards addressing the above issues, and hence this research attempts to take advantage of these platforms to achieve efficient SPR generation and exciton coupling for biosensing applications. The overarching scope of this dissertation extends to the design, fabrication, and optimization of metal NS and NL structures for SPR generation and sensing applications. Emphasis is placed on investigating the mechanism of optical signal enhancement arising from plasmon-exciton coupling (PEC) with particular focus on (a) exploring the role of geometry and size of the nanostructures (b) examining the influence of SPR spectral mode overlap with exciton’s absorption and/or emission energies on the overall optical signal in a NS or NL system, and (c) investigating the analytical sensitivity and signal transduction of the PEC system to biomolecular interactions. The nanoimprinting technique based on soft lithography for NS fabrication, which is used in this work for NS array fabrication, required addressing a critical issue, namely PDMS diffusion into nanoscale patterns for high aspect ratio realization. This was mitigated by curing temperature variation and incubation time to achieve 50 nm-130 nm width NS arrays with an intense, broad spectral response that red-shifts and diminishes with increasing NS width. The 50 nm width structure exhibited ~57× optical enhancement when coupled with acridine orange, a fluorescence dye, whose absorption and emission spectra closely overlaps with plasmonic spectra. A sensitive assay for detecting DNA hybridization was generated using the interaction of the selected SARS-CoV-2 ssDNA and dsDNA with AO to trigger the metachromatic behaviour of the dye to produce a strong optical signal amplification on the formation of AO-ssDNA complex and a quenched signal upon hybridization to the complementary target DNA along with a blue shift in the fluorescence of AO-dsDNA. The SARS-CoV-2 DNA hybridization assay, based on the PEC exhibited 0.21 nM sensitivity to complementary strand target, distinguished 1-, 2-, and 3-base mismatched DNA targets, reusability of ~6 x with 96% signal recovery, stable for up to 10 days at room temperature. Regarding the NL sensing platform, the principle of the sensing mechanism is based on plasmon-mediated extraordinary optical transmission (EOT) whose wavelength red-shifts with increase in refractive index (RI) at near-metal surface. The NL plasmonic-based biosensor fabricated using a patented E-beam writing method exhibited ~ 384.08 nm/RIU sensitivity, limit of detection to cardiac troponin I (TnI) at 0.079 ng/mL, 0.084 ng/mL and 0.097 ng/mL in PBS buffer, human serum, and human blood, respectively. The direct measurement of TnI in whole human blood without any purification or sample preparation step highlights the significance of the sensing platform for point-of-care detection. Thus, this work innovates (a) a tunable SPR to meet the requirement for plasmon-exciton spectral overlap for optical signal amplification, (b) the mechanism of optical enhancements due to PEC in NS arrays, and (c) a new application of PEC in NS and EOT in NL for the sensitive detection of SARS-CoV-2 DNA hybridization and cardiovascular biomarker TnI in human blood, respectively. The enhanced light-matter interactions have a broader impact beyond healthcare to light harvesting for solar cells, heat generation for cancer therapy, and photocatalysis for nanoscale reactions like water splitting

Enacting Inquiry Learning in Mathematics through History

International audienceWe explain how history of mathematics can function as a means for enacting inquiry learning activities in mathematics as a scientific subject. It will be discussed how students develop informed conception about i) the epistemology of mathematics, ii) of how mathematicians produce mathematical knowledge, and iii) what kind of questions that drive mathematical research. We give examples from the mathematics education at Roskilde University and we show how (teacher) students from this program are themselves capable of using history to establish inquiry learning environments in mathematics in high school. The realization is argued for in the context of an explicit-reflective framework in the sense of Abd-El-Khalick (2013) and his work in science education