Design Review Report: Zero G Design Group

The purpose of this report is to describe the design, construction, and testing of an apparatus capable of testing and recording the deployment of thin film shells in a microgravity environment. The group has designed a prototype and ideal model to test a deceleration system that, in full scale, would provide sufficient deceleration without harming the testing apparatus. This project does not involve dropping the constructed apparatus and equipment. A counter weight chain and pulley system was chosen as the deceleration prototype for testing. Issues with budget and time constraints have limited aspects originally planned for completion in this phase of the project. Budgetary issues have restricted mounting of the electrical components within the fabricated apparatus and purchasing housing for the enclosure. Data from the prototype tests from the counterweight deceleration were collected and compared to an ideal model. Analysis of results determined that a counterweight system is sufficient for decelerating the load, but modifications need to be made to the model to accurately predict its behavior. Despite issues integrating the full system with the Efika, the automation timing sequence and video recording drivers have been successfully written and tested. In the face of obstacles and delays, the project is taking shape and the group feels confident with its direction and design

Uncovering convolutional neural network decisions for diagnosing multiple sclerosis on conventional MRI using layer-wise relevance propagation

Machine learning-based imaging diagnostics has recently reached or even superseded the level of clinical experts in several clinical domains. However, classification decisions of a trained machine learning system are typically non-transparent, a major hindrance for clinical integration, error tracking or knowledge discovery. In this study, we present a transparent deep learning framework relying on convolutional neural networks (CNNs) and layer-wise relevance propagation (LRP) for diagnosing multiple sclerosis (MS). MS is commonly diagnosed utilizing a combination of clinical presentation and conventional magnetic resonance imaging (MRI), specifically the occurrence and presentation of white matter lesions in T2-weighted images. We hypothesized that using LRP in a naive predictive model would enable us to uncover relevant image features that a trained CNN uses for decision-making. Since imaging markers in MS are well-established this would enable us to validate the respective CNN model. First, we pre-trained a CNN on MRI data from the Alzheimer's Disease Neuroimaging Initiative (n = 921), afterwards specializing the CNN to discriminate between MS patients and healthy controls (n = 147). Using LRP, we then produced a heatmap for each subject in the holdout set depicting the voxel-wise relevance for a particular classification decision. The resulting CNN model resulted in a balanced accuracy of 87.04% and an area under the curve of 96.08% in a receiver operating characteristic curve. The subsequent LRP visualization revealed that the CNN model focuses indeed on individual lesions, but also incorporates additional information such as lesion location, non-lesional white matter or gray matter areas such as the thalamus, which are established conventional and advanced MRI markers in MS. We conclude that LRP and the proposed framework have the capability to make diagnostic decisions of..

Neural Processes of Psychological Stress and Relaxation Predict the Future Evolution of Quality of Life in Multiple Sclerosis

Health-related quality of life (HRQoL) is an essential complementary parameter in the assessment of disease burden and treatment outcome in multiple sclerosis (MS) and can be affected by neuropsychiatric symptoms, which in turn are sensitive to psychological stress. However, until now, the impact of neurobiological stress and relaxation on HRQoL in MS has not been investigated. We thus evaluated whether the activity of neural networks triggered by mild psychological stress (elicited in an fMRI task comprising mental arithmetic with feedback) or by stress termination (i.e., relaxation) at baseline (T0) predicts HRQoL variations occurring between T0 and a follow-up visit (T1) in 28 patients using a robust regression and permutation testing. The median delay between T0 and T1 was 902 (range: 363-1,169) days. We assessed HRQoL based on the Hamburg Quality of Life Questionnaire in MS (HAQUAMS) and accounted for the impact of established HRQoL predictors and the cognitive performance of the participants. Relaxation-triggered activity of a widespread neural network predicted future variations in overall HRQoL (t = 3.68, p(family-wise error [FWE])-corrected = 0.008). Complementary analyses showed that relaxation-triggered activity of the same network at baseline was associated with variations in the HAQUAMS mood subscale on an alpha(FWE) = 0.1 level (t = 3.37, p(FWE) = 0.087). Finally, stress-induced activity of a prefronto-limbic network predicted future variations in the HAQUAMS lower limb mobility subscale (t = -3.62, p(FWE) = 0.020). Functional neural network measures of psychological stress and relaxation contain prognostic information for future HRQoL evolution in MS independent of clinical predictors

Altered Coupling of Psychological Relaxation and Regional Volume of Brain Reward Areas in Multiple Sclerosis

Background:Psychological stress can influence the severity of multiple sclerosis (MS), but little is known about neurobiological factors potentially counteracting these effects. Objective:To identify gray matter (GM) brain regions related to relaxation after stress exposure in persons with MS (PwMS). Methods:36 PwMS and 21 healthy controls (HCs) reported their feeling of relaxation during a mild stress task. These markers were related to regional GM volumes, heart rate, and depressive symptoms. Results:Relaxation was differentially linked to heart rate in both groups (t= 2.20,p= 0.017), i.e., both markers were only related in HCs. Relaxation was positively linked to depressive symptoms across all participants (t= 1.99,p= 0.045) although this link differed weakly between groups (t= 1.62,p= 0.108). Primarily, the volume in medial temporal gyrus was negatively linked to relaxation in PwMS (t= -5.55, p(family-wise-error(FWE)corrected)= 0.018). A group-specific coupling of relaxation and GM volume was found in ventromedial prefrontal cortex (VMPFC) (t= -4.89, p(FWE)= 0.039). Conclusion:PwMS appear unable to integrate peripheral stress signals into their perception of relaxation. Together with the group-specific coupling of relaxation and VMPFC volume, a key area of the brain reward system for valuation of affectively relevant stimuli, this finding suggests a clinically relevant misinterpretation of stress-related affective stimuli in MS

Ultrabroadband Density of States of Amorphous In-Ga-Zn-O

The sub-gap density of states of amorphous indium gallium zinc oxide ($a$-IGZO) is obtained using the ultrabroadband photoconduction (UBPC) response of thin-film transistors (TFTs). Density functional theory simulations classify the origin of the measured sub-gap density of states peaks as a series of donor-like oxygen vacancy states and acceptor-like Zn vacancy states. Donor peaks are found both near the conduction band and deep in the sub-gap, with peak densities of $10^{17}-10^{18}$ cm$^{-3}$eV$^{-1}$. Two deep acceptor-like metal vacancy peaks with peak densities in the range of $10^{18}$ cm$^{-3}$eV$^{-1}$ and lie adjacent to the valance band Urbach tail region at 2.0 to 2.5 eV below the conduction band edge. By applying detailed charge balance, we show increasing the density of metal vacancy deep-acceptors strongly shifts the $a$-IGZO TFT threshold voltage to more positive values. Photoionization (h$\nu$ > 2.0 eV) of metal vacancy acceptors is one cause of transfer curve hysteresis in $a$-IGZO TFTs owing to longer recombination lifetimes as they get captured into acceptor-like vacancies.Comment: 31 pages, 5 figures, supplementary section include

Search for Pair-Produced Resonances Decaying to Quark Pairs in Proton-Proton Collisions at √s = 13 TeV

A general search for the pair production of resonances, each decaying to two quarks, is reported. The search is conducted separately for heavier resonances (masses above 400 GeV), where each of the four final-state quarks generates a hadronic jet resulting in a four-jet signature, and for lighter resonances (masses between 80 and 400 GeV), where the pair of quarks from each resonance is collimated and reconstructed as a single jet resulting in a two-jet signature. In addition, a b-tagged selection is applied to target resonances with a bottom quark in the final state. The analysis uses data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 35.9  fb⁻¹, from proton-proton collisions at a center-of-mass energy of 13 TeV. The mass spectra are analyzed for the presence of new resonances, and are found to be consistent with standard model expectations. The results are interpreted in the framework of R-parity-violating supersymmetry assuming the pair production of scalar top quarks decaying via the hadronic coupling λ′′312 or λ′′323 and upper limits on the cross section as a function of the top squark mass are set. These results probe a wider range of masses than previously explored at the LHC, and extend the top squark mass limits in the ˜t→qq′ scenario

Search for electroweak production of charginos and neutralinos in multilepton final states in proton-proton collisions at √s = 13 TeV

Results are presented from a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more leptons, which can include up to two hadronically decaying tau leptons. The results are based on a sample of proton-proton collision data collected at s√=13 TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb⁻¹. The observed event yields are consistent with the expectations based on the standard model. The results are interpreted in simplified models of supersymmetry describing various scenarios for the production and decay of charginos and neutralinos. Depending on the model parameters chosen, mass values between 180 GeV and 1150 GeV are excluded at 95% CL. These results significantly extend the parameter space probed for these particles in searches at the LHC. In addition, results are presented in a form suitable for alternative theoretical interpretations

Search for Standard Model Production of Four Top Quarks with Same-Sign and Multilepton Final States in Proton–proton Collisions at √s = 13 TeV

A search for standard model production of four top quarks (tt¯tt¯) is reported using events containing at least three leptons (e,μ) or a same-sign lepton pair. The events are produced in proton–proton collisions at a center-of-mass energy of 13TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9fb[superscript −1]. Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the tt¯tt¯ cross section is measured to be 16.9[superscript +13.8][subscript −11.4] fb, in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level