#lets-discuss:Analyzing Student Affect in Course Forums Using Emoji

Emoji are commonly used in social media to convey attitudes and emotions. While popular, their use in educational contexts has been sparsely studied. This paper reports on the students’ use of emoji in an online course forum in which students annotate and discuss course material in the margins of the online textbook. For this study, instructors created 11 custom emoji-hashtag pairs that enabled students to quickly communicate affects and reactions in the forum that they experienced while interacting with the course material. Example reporting includes, inviting discussion about a topic, declaring a topic as interesting, or requesting assistance about a topic. We analyze emoji usage by over 1,800 students enrolled in multiple offerings of the same course across multiple academic terms. The data show that some emoji frequently appear together in posts associated with the same paragraphs, suggesting that students use the emoji in this way to communicating complex affective states. We explore the use of computational models for predicting emoji at the post level, even when posts are lacking emoji. This capability can allow instructors to infer information about students’ affective states during their”at home” interactions with course readings. Finally, we show that partitioning the emoji into distinct groups, rather than trying to predict individual emoji, can be both of pedagogical value to instructors and improve the predictive performance of our approach using the BERT language model. Our procedure can be generalized to other courses and for the benefit of other instructors

Structural basis of tRNA modification with CO2 fixation and methylation by wybutosine synthesizing enzyme TYW4†

Wybutosine (yW), one of the most complicated modified nucleosides, is found in the anticodon loop of eukaryotic phenylalanine tRNA. This hypermodified nucleoside ensures correct codon recognition by stabilizing codon-anticodon pairings during the decoding process in the ribosome. TYW4 is an S-adenosylmethionine (SAM)-dependent enzyme that catalyzes the final step of yW biosynthesis, methylation and methoxycarbonylation. However, the structural basis for the catalytic mechanism by TYW4, and especially that for the methoxycarbonylation, have remained elusive. Here we report the apo and cofactor-bound crystal structures of yeast TYW4. The structures revealed that the C-terminal domain folds into a β-propeller structure, forming part of the binding pocket for the target nucleoside. A comparison of the apo, SAM-bound, and S-adenosylhomocysteine-bound structures of TYW4 revealed a drastic structural change upon cofactor binding, which may sequester solvent from the catalytic site during the reaction and facilitate product release after the reaction. In conjunction with the functional analysis, our results suggest that TYW4 catalyzes both methylation and methoxycarbonylation at a single catalytic site, and in the latter reaction, the methoxycarbonyl group is formed through the fixation of carbon dioxide

Structure-Function Analysis of Human TYW2 Enzyme Required for the Biosynthesis of a Highly Modified Wybutosine (yW) Base in Phenylalanine-tRNA

Posttranscriptional modifications are critical for structure and function of tRNAs. Wybutosine (yW) and its derivatives are hyper-modified guanosines found at the position 37 of eukaryotic and archaeal tRNAPhe. TYW2 is an enzyme that catalyzes α-amino-α-carboxypropyl transfer activity at the third step of yW biogenesis. Using complementation of a ΔTYW2 strain, we demonstrate here that human TYW2 (hTYW2) is active in yeast and can synthesize the yW of yeast tRNAPhe. Structure-guided analysis identified several conserved residues in hTYW2 that interact with S-adenosyl-methionine (AdoMet), and mutation studies revealed that K225 and E265 are critical residues for the enzymatic activity. We previously reported that the human TYW2 is overexpressed in breast cancer. However, no difference in the tRNAPhe modification status was observed in either normal mouse tissue or a mouse tumor model that overexpresses Tyw2, indicating that hTYW2 may have a role in tumorigenesis unrelated to yW biogenesis

Agminated syringocystadenoma papilliferum: a new clinical presentation of a rare benign adnexal neoplasm

Syringocystadenoma papilliferum is a rare adnexal tumor that often occurs as a solitary tumor in the head and neck region, although occurrences on other anatomical locations have been described. Linear configurations have been described, but an agminated form is a more rare and underreported variant of this tumor. We describe a case of a healthy 10-year old female with agminated syringocystadenoma papilliferum occurring on her left supraclavicular region, with the clinical appearance of grouped molluscum contagiosum papules.Case synopsisA healthy 10-year-old girl was referred for the treatment of a "collection of molluscum contagiosum" of the left supra clavicular region of several years duration. The lesions were asymptomatic and refractory to cryotherapy. The patient was a healthy girl with no significant systemic findings. Cutaneous exam revealed a clustered group of pink, dome shaped, umbilicated papules over a 1.5 x 1 cm area within the left supraclavicular fossa (Figure 1a). An excisional biopsy was performed. Routine H&E stained sections revealed cystic epidermal invaginations with papillary projections. The superficial portions of the cyst were lined by stratified keratinizing epithelium, whereas the deeper papillated portion exhibited a double layer of basal-like cells and luminal eosinophilic columnar cells with focal decapitation secretion. The papillary structures contained fibrovascular cores and lymphoplasmacytic infiltrates. A component of hamartomatous follicular growth was not identified (Figure 1b-d.).  A diagnosis was made of agminated syringocystadenoma papilliferum