Chaos, Complexity, and Random Matrices

Chaos and complexity entail an entropic and computational obstruction to describing a system, and thus are intrinsically difficult to characterize. In this paper, we consider time evolution by Gaussian Unitary Ensemble (GUE) Hamiltonians and analytically compute out-of-time-ordered correlation functions (OTOCs) and frame potentials to quantify scrambling, Haar-randomness, and circuit complexity. While our random matrix analysis gives a qualitatively correct prediction of the late-time behavior of chaotic systems, we find unphysical behavior at early times including an $\mathcal{O}(1)$ scrambling time and the apparent breakdown of spatial and temporal locality. The salient feature of GUE Hamiltonians which gives us computational traction is the Haar-invariance of the ensemble, meaning that the ensemble-averaged dynamics look the same in any basis. Motivated by this property of the GUE, we introduce $k$-invariance as a precise definition of what it means for the dynamics of a quantum system to be described by random matrix theory. We envision that the dynamical onset of approximate $k$-invariance will be a useful tool for capturing the transition from early-time chaos, as seen by OTOCs, to late-time chaos, as seen by random matrix theory.Comment: 61 pages, 14 figures; v2: references added, typos fixe

Tor Bridge Distribution Powered by Threshold RSA

Since its inception, Tor has offered anonymity for internet users around the world. Tor now offers bridges to help users evade internet censorship, but the primary distribution schemes that provide bridges to users in need have come under attack. This thesis explores how threshold RSA can help strengthen Tor\u27s infrastructure while also enabling more powerful bridge distribution schemes. We implement a basic threshold RSA signature system for the bridge authority and a reputation-based social network design for bridge distribution. Experimental results are obtained showing the possibility of quick responses to requests from honest users while maintaining both the secrecy and the anonymity of registered clients and bridges

Model-based evaluation of cost-effectiveness of nerve growth factor inhibitors in knee osteoarthritis: impact of drug cost, toxicity, and means of administration

Studies suggest nerve growth factor inhibitors (NGFi) relieve pain but may accelerate disease progression in some patients with osteoarthritis (OA). We sought cost and toxicity thresholds that would make NGFi a cost-effective treatment for moderate-to-severe knee OA

Cost-effectiveness of nonsteroidal anti-inflammatory drugs and opioids in the treatment of knee osteoarthritis in older patients with multiple comorbidities

To evaluate long-term clinical and economic outcomes of naproxen, ibuprofen, celecoxib or tramadol for OA patients with cardiovascular disease (CVD) and diabetes

Association of urinary metabolites with radiographic progression of knee osteoarthritis in overweight and obese adults: an exploratory study

Metabolic factors may contribute to osteoarthritis (OA).This study employed metabolomics analyses to determine if differences in metabolite profiles could distinguish people with knee OA who exhibited radiographic progression

Evaluating knowledge of falls risk factors and falls prevention strategies among lower extremity amputees after inpatient prosthetic rehabilitation: a prospective study

Purpose: Falls are prevalent among people with lower extremity amputations. A knowledge of risk factors is important in preventing falls, though no research has evaluated patient understanding of falls in this population. The study objective was to evaluate knowledge of falls risk factors and falls prevention strategies at discharge and 4-months after inpatient prosthetic rehabilitation. Methods: Participants completed a falls questionnaires with four sections: (1) falls during rehabilitation and after discharge, (2) falls self-efficacy using the Activities-specific Balance Confidence scale, (3) knowledge of falls risk factors, and (4) falls prevention strategies. Questionnaire responses were quantified using means and standard deviations or frequencies and percentages. Data were analyzed using paired t-tests for the Activities-specific Balance Confidence scale and the knowledge of falls risk factors, and using chi-square analyses for fall prevention strategies. Results: Twenty-seven individuals (aged 62.6 ± 8.4; 55.6% male) were included. Unsafe or risky behaviours and not paying attention to surroundings were perceived as the top two falls risk factors. Although these factors are modifiable, only 5.9% of participants listed preventative behavioural modifications. No significant differences were found in Activities-specific Balance Confidence scale scores (p = 0.404) or knowledge of falls risk factors (p = 0.361) between discharge and follow-up. Conclusion: This study highlights a gap between knowledge of falls risk factors and the application of knowledge to prevent falls. Follow-up data suggest that lived experience does not affect the knowledge of falls risk factors

OXPHOS Inhibition via LUC7L2 as a Target for SF3B1-Mutant Myelodysplastic Syndrome

SF3B1 gene mutations are the most common spliceosome mutations seen in myelodysplastic syndrome (MDS) patients. Though it is well known SF3B1 mutations cause downstream changes in erythroid differentiation and the cell cycle, which leads to malignancy, metabolic changes arising from this mutation are unknown. We conducted RNA sequencing from SF3B1-mutant MDS patient samples and found several genes related to metabolism were alternatively spliced. Of these, LUC7L2 was selected as our target as previous studies show its involvement in promoting oxidative phosphorylation (OXPHOS) via various downstream mechanisms when knocked down.We show that OXPHOS is increased in MOLM-13 myeloid malignant cells when LUC7L2 is inhibited. The results suggested that this gene, which is alternatively spliced and shows lower expression in SF3B1-mutant MDS, increases myeloid malignant dependence on OXPHOS