Although it is agreed that physicochemical features of molecules determine their perceived odor, the rules governing this relationship remain unknown. A significant obstacle to such understanding is the high dimensionality of features describing both percepts and molecules. We applied a statistical method to reduce dimensionality in both odor percepts and physicochemical descriptors for a large set of molecules. We found that the primary axis of perception was odor pleasantness, and critically, that the primary axis of physicochemical properties reflected the primary axis of olfactory perception. This allowed us to predict the pleasantness of novel molecules by their physicochemical properties alone. Olfactory perception is strongly shaped by experience and learning. However, our findings suggest that olfactory pleasantness is also partially innate, corresponding to a natural axis of maximal discriminability among biologically relevant molecules.

Students' motivations in choosing a career in the health professions are of great interest for educators and admission committees, particularly in the ield of dentistry. This study conducted in four private dental institutions in India was designed to investigate dental students' motivations in their choice of dentistry as a career and their perceptions regarding dentistry in India. A total of 400 questionnaires were distributed, and 369 students responded in a combination of selected responses to the questions, for a response rate of 92.3 percent. In the results, 53.7 percent of the students reported pursuing dentistry because it offers stable work (p<0.002); 38.7 percent because the profession is highly paid; and 7.6 percent due to the ease in inding a regular job in dental schools or hospitals. The survey also found that 44.4 percent of the students pursued dentistry because they can determine their own hours of work and 36.6 percent said they liked to be their own boss. Among these students, 64.5 percent said they were content to be joining dentistry as a professional course, but 35.5 percent were discontented (p<0.001). Regarding the specialties, 79.1 percent said they want to become specialists in the ield of dentistry (p<0.001); oral surgery was the leading choice followed by orthodontics. Only 11.7 percent reported wanting to pursue dentistry for research purposes. Overall, this study found that inancial and professional factors were the chief criteria for students' pursuing dentistry in India; however, the strongest inluence in the choice of dentistry was the students' parents or family.

Background. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or COVID-19) continues to spread globally. It has become a major cause of concern for health care professionals all over the world. Objective. The aim of this study was to assess knowledge, awareness and hygiene practices regarding COVID-19 among private dental practitioners practicing in Tricity (Chandigarh, Panchkula and Mohali) in India during these critical times. Materials and Methods. A total of 245 private dentists participated in this cross-sectional survey and finally 215 constituted the final sample size. A self-administered, multiple choice type questionnaire (verified by a specialist) was administered to obtain information from the subjects. The questionnaire was divided into two parts and included 15 questions on knowledge and awareness regarding COVID-19. Statistical analysis was done using ANOVA and Student’s t-test. Results. Percentage of subjects who answered correctly regarding main symptoms of COVID-19 and primary mode of transmission was 87% and 82.5% respectively. One-third of the subjects were not aware regarding Personal Protective Equipment (PPE) to be used while rendering dental treatment. 75% of subjects were of the opinion that supportive care is the current treatment regime for COVID-19. Less than one-third of subjects (30.2%) reported high scores. Education level (p=0.018) and health sector profile (p=0.024) of the subjects were significantly associated with mean knowledge scores. Conclusion. The findings of the present study showed that some notable deficiencies in knowledge existed among dental professionals regarding some vital aspects of COVID-19. Therefore, there is an urgent need for improving dentists’ knowledge via health education and training programs. Further studies on the subject are also warranted once the situation normalizes.

Background: Differentiating glioblastoma, brain metastasis, and central nervous system lymphoma (CNSL) on conventional magnetic resonance imaging (MRI) can present a diagnostic dilemma due to the potential for overlapping imaging features. We investigate whether machine learning evaluation of multimodal MRI can reliably differentiate these entities. Methods: Preoperative brain MRI including diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE), and dynamic susceptibility contrast (DSC) perfusion in patients with glioblastoma, lymphoma, or metastasis were retrospectively reviewed. Perfusion maps (rCBV, rCBF), permeability maps (K-trans, Kep, Vp, Ve), ADC, T1C+ and T2/FLAIR images were coregistered and two separate volumes of interest (VOIs) were obtained from the enhancing tumor and non-enhancing T2 hyperintense (NET2) regions. The tumor volumes obtained from these VOIs were utilized for supervised training of support vector classifier (SVC) and multilayer perceptron (MLP) models. Validation of the trained models was performed on unlabeled cases using the leave-one-subject-out method. Head-to-head and multiclass models were created. Accuracies of the multiclass models were compared against two human interpreters reviewing conventional and diffusion-weighted MR images. Results: Twenty-six patients enrolled with histopathologically-proven glioblastoma (n=9), metastasis (n=9), and CNS lymphoma (n=8) were included. The trained multiclass ML models discriminated the three pathologic classes with a maximum accuracy of 69.2% accuracy (18 out of 26; kappa 0.540, P=0.01) using an MLP trained with the VpNET2 tumor volumes. Human readers achieved 65.4% (17 out of 26) and 80.8% (21 out of 26) accuracies, respectively. Using the MLP VpNET2 model as a computer-aided diagnosis (CADx) for cases in which the human reviewers disagreed with each other on the diagnosis resulted in correct diagnoses in 5 (19.2%) additional cases. Conclusions: Our trained multiclass MLP using VpNET2 can differentiate glioblastoma, brain metastasis, and CNS lymphoma with modest diagnostic accuracy and provides approximately 19% increase in diagnostic yield when added to routine human interpretation.

Study design: Prospective Pilot Study. Objectives: To determine the safety and feasibility of autologous olfactory mucosal transplantation into the spinal cord in chronic spinal cord injured using the technique developed by Carlos Lima et al. Setting: Spinal Injury Center, New Delhi. Methods: Five chronic, motor complete, traumatic spinal cord injury (SCI) patients with neurological level C5-T12 underwent the procedure. Participants were assessed at baseline and at 6 monthly intervals. Safety and tolerability were evaluated through monitoring for any adverse events and tests including magnetic resonance imaging (MRI) evaluation. Efficacy assessment was done through neurological, functional and psychological evaluation, electrophysiological studies and urodynamics. Results: Surgery was tolerated well by all American Spinal Injury Association (ASIA) Impairment Scale (AIS) A participants. The only AIS B participant lost sensory scores significantly after surgery but is gradually regaining it. MRI evaluation revealed a syrinx in one participant and increase in length of myelomalacia in four participants. There were no other adverse findings on MRI evaluation. There was no significant improvement in any of the neurological, electrophysiological or urodynamic efficacy variables. Statistically significant improvement was seen in functional scores as evaluated by Spinal Cord Independence Measure, Beck Depression Inventory scores and life impact scores on International Spinal Cord Injury Scale. Conclusions: The procedure is relatively safe and feasible in AIS A participants with thoracic level injuries at 18 month follow-up. No efficacy could be demonstrated which could be attributed to the procedure.