Delineation of the subthalamic nuclei on MRI is critical for deep brain stimulation surgery in patients with Parkinson’s disease. We propose this retrospective cohort study for quantitative analysis of MR signal-to-noise ratio, contrast, and signal difference-to-noise ratio of the STN on pre-operative three-dimensional stereotactic MRI in patients with medication-refractory PD. Forty-five consecutive patients with medication-refractory PD who underwent STN-DBS surgery in our hospital from January 2018 to June 2021 were included in this study. All patients had whole-brain 3D MRI, including (...) T2-weighted imaging, T2-weighted fluid-attenuated inversion recovery, and susceptibility-weighted imaging, at 3.0 T scanner for stereotactic navigation. The signal intensities of the STN, corona radiata, and background noise were obtained after placing regions of interest on corresponding structures. Quantitative comparisons of SNR, contrast, and SDNR of the STN between MR pulse sequences, including the T2WI, FLAIR, and SWI. Subgroup analysis regarding patients’ sex, age, and duration of treatment. We used one-way repeated measures analysis of variance for quantitative comparisons of SNR, contrast, and SDNR of the STN between different MR pulse sequences, and we also used the dependent t-test for the post hoc tests. In addition, we used Mann–Whitney U test for subgroup analyses. Both the contrast and SDNR were highest on FLAIR. The SNR was highest on SWI, and both the SNR and SDNR were lowest on T2WI. Subgroup analyses demonstrated significantly lower SDNR on SWI for patients receiving medication treatment for ≥13 years. In conclusion, on 3D stereotactic MRI of medication-refractory PD patients, the contrast and SDNR for the STN are highest on FLAIR, suggesting the optimal delineation of STN on FLAIR. (shrink)

Efforts from diverse disciplines, including evolutionary studies and biomechanical experiments, have yielded new insights into the genetic, signaling, and mechanical control of tooth formation and functions. Evidence from fossils and non‐model organisms has revealed that a common set of genes underlie tooth‐forming potential of epithelia, and changes in signaling environments subsequently result in specialized dentitions, maintenance of dental stem cells, and other phenotypic adaptations. In addition to chemical signaling, tissue forces generated through epithelial contraction, differential growth, and skeletal constraints act (...) in parallel to shape the tooth throughout development. Here recent advances in understanding dental development from these studies are reviewed and important gaps that can be filled through continued application of evolutionary and biomechanical approaches are discussed. (shrink)

This text is a bilingual Arabic-English translation of one of the most important metaphysical works of the Persian Muslim philosopher known as Mulla Sadra & Sadr al-Din Muhammad al-Shirazi. In this work Mulla Sadra develops an anti-Platonic philosophical position which is non-Aristotelian. He holds that "existents" are ontologically prior to "essence" & that there are two different realms -- the mind dependent domain & entities which exist independent of the mind. Mulla Sadra's views became very popular among Iranian Muslim philosophers (...) & eventually were instrumental in destroying the Aristotelian school of thought in the Islamic world. The translator, Dr. Parviz Morewedge, is the Secretary-Treasurer of the Society for the Study of Islamic Philosophy & Science & has published ten books & numerous articles in Islamic Philosophy & Mysticism. (shrink)

The Nasirean Ethics is the best known ethical digest to be composed in medieval Persia, if not in all mediaeval Islam. It appeared initially in 633/1235 when Tūsī was already a celebrated scholar, scientist, politico-religious propagandist. The work has a special significance as being composed by an outstanding figure at a crucial time in the history he was himself helping to shape: some twenty years later Tūsī was to cross the greatest psychological watershed in Islamic civilization, playing a leading part (...) in the capture of Baghdad and the extinction of the generally acknowledged Caliphate there. In this work the author is primarily concerned with the criteria of human behaviour: first in terms of space and priority allotted, at the individual level, secondly, at the economic level and thirdly at the political level. (shrink)

Ismailites -Doctrines ; Assassins (Ismailites).