Performance Enhancement of Opto-electronic Oscillators using Photonic Bandgap Phase and Mach-Zehnder Modulators

Highly stable oscillators are an important component in heterodyne receivers used in telecommunications, remote sensing, and instrumentation. Stable oscillators require high quality factor (Q) resonators that are challenging at radio frequencies of above 1GHz. The opto-electronic oscillators (OEO) using long low-loss fiber optic (FO) delay lines are developed for stable local oscillators for a variety of radio frequency (RF) applications at frequencies of 10 GHz and above. The OEO takes advantage of optical modulation by stable RF signal before transmission over kilometer long fiber spools. The optical modulation is being done using phase modulation, or interferometric modulation using the Mach-Zehnder modulator (MZM). The phase sensitivity of the phase modulator (PM) and its losses influence the behavior of the PM or MZM, which is a critical component to the overall performance of FO delay line in the OEO, and particularly for the forced oscillation neucleation noise of the OEOs using self-injection locking (SIL) and self-phase locking (SPLL). To improve on sensitivity of the optical modulators, photonic bandgap (PBG) based PM and MZM structures are considered with electro-optic (EO) polymers to increase the modulation efficiency and modulation bandwidth using integrated Si-photonics structures. This thesis covers the modeling and performance of the OEO with both PBG based and the conventional realization of PMs and MZMs each with various insertion loss and half-wave voltage performance characteristics. The half-wave voltage, Vπ, of the modulators is the voltage necessary to achieve a π radian (180o) phase shift. The phase noise and frequency stability at close-in and far away from carrier is analyzed with MZMs operating at the quadrature point (Vπ/2) and their impact is demonstrated on the overall SILPLL OEO performance. The previously developed and experimentally demonstrated self-injection locked phase locked loop (SILPLL) OEO is used and the performance is predicted when a PBG based modulator with a Vπ of 2.17V and optical insertion loss of 1.6dB is used. The forced oscillation techniques of SIL and SPLL are also modeled to reduce the close-in to carrier phase noise of a 10GHz OEO. A Sagnac loop topology is analyzed and modeled as a method of performing the PM-IM conversion for the PM based OEO. The simulated phase noise performance for the PBG based PM is -149.6dBc/Hz as compared to -142.8dBc/Hz at 10kHz offset frequency for a conventional Lithium Niobate (LN) PM. At 10MHz offset frequency, the simulated phase noise is dominated by the amplitude noise of the FO delay line and for the PBG based PM is -166.5dBc/Hz compared to -158.3dBc/Hz for the conventional LN based PM. For the PBG based MZM, the simulated phase noise is -146.9dBc/Hz compared to -144.0dBc/Hz for the conventional MZM and -163.8dBc/Hz compared to -160.9dBc/Hz at offset frequency of 10kHz and 10MHz respectively. Time domain analyses of the Allan deviation and timing jitter are performed for each modulator and OEO topology. The Allan deviation at a sampling time of 10ms for the PBG based PM in the Sagnac loop SILPLL OEO was estimated to be 1.80x10-12, with an improvement from 2.80x10-12 for the conventional PM. Using the same topology, a jitter of 11.2fs was estimated, improving on calculated jitters of the conventional PM by 17.3fs. For the PBG based MZM in the SILPLL forced OEO, the Allan deviation at a sampling time of 10ms was calculated to be 2.47x10-12, improving by 2.40x10-12 from the conventional PM. A jitter of 15.3fs is expected, reducing by 14.9fs from the conventional PM's jitters. An analytical modeling and performance enhancement of both the standard and SILPLL OEO were presented in this thesis. Recommendation for experimental validations is also made in this thesis.M.S., Electrical Engineering -- Drexel University, 201

Oral contraceptives combined with interferon β in multiple sclerosis

Objective: To test the effect of oral contraceptives (OCs) in combination with interferon b (IFN-b) on disease activity in patients with relapsing-remitting multiple sclerosis (RRMS). Methods: One hundred fifty women with RRMS were randomized in a 1:1:1 ratio to receive IFNb-1a subcutaneously (SC) only (group 1), IFN-b-1a SC plus ethinylstradiol 20 mg and desogestrel 150 mg (group 2), or IFN-b-1a SC plus ethinylestradiol 40 mg and desogestrel 125 mg (group 3). The primary endpoint was the cumulative number of combined unique active (CUA) lesions on brain MRI at week 96. Secondary endpoints included MRI and clinical and safety measures. Results: The estimated number of cumulative CUA lesions at week 96 was 0.98 (95% confidence interval [CI] 0.81–1.14) in group 1, 0.84 (95% CI 0.66–1.02) in group 2, and 0.72 (95% CI 0.53–0.91) in group 3, with a decrease of 14.1% (p 5 0.24) and 26.5% (p 5 0.04) when comparing group 1 with groups 2 and 3, respectively. The number of patients with no gadoliniumenhancing lesions was greater in group 3 than in group 1 (p 5 0.03). No significant differences were detected in other secondary endpoints. IFN-b or OC discontinuations were equally distributed across groups. Conclusions: Our results translate the observations derived from experimental models to patients, supporting the anti-inflammatory effects of OCs with high-dose estrogens, and suggest possible directions for future research

Impeller optimization in crossflow hydraulic turbines

Crossflow turbines represent a valuable choice for energy recovery in aqueducts, due to their constructive simplicity and good efficiency under variable head jump conditions. Several experimental and numerical studies concerning the optimal design of crossflow hydraulic turbines have already been proposed, but all of them assume that structural safety is fully compatible with the sought after geometry. We show first, with reference to a specific study case, that the geometry of the most efficient impeller would lead shortly, using blades with a traditional circular profile made with standard material, to their mechanical failure. A methodology for fully coupled fluid dynamic and mechanical optimization of the blade cross-section is then proposed. The methodology assumes a linear variation of the curvature of the blade external surface, along with an iterative use of two-dimensional (2D) computational fluid dynamic (CFD) and 3D structural finite element method (FEM) simulations. The proposed methodology was applied to the design of a power recovery system (PRS) turbine already installed in an operating water transport network and was finally validated with a fully 3D CFD simulation coupled with a 3D FEM structural analysis of the entire impeller

General Relativistic Dynamics of Irrotational Dust: Cosmological Implications

The non--linear dynamics of cosmological perturbations of an irrotational collisionless fluid is analyzed within General Relativity. Relativistic and Newtonian solutions are compared, stressing the different role of boundary conditions in the two theories. Cosmological implications of relativistic effects, already present at second order in perturbation theory, are studied and the dynamical role of the magnetic part of the Weyl tensor is elucidated.Comment: 12 pages , DFPD 93/A/6

Effect on cognition of estroprogestins combined with Interferon beta in multiple sclerosis: analysis of secondary outcomes from a randomized controlled trial

Introduction Cognitive impairment is a disabling symptom in multiple sclerosis (MS). While its management remains challenging, beneficial effects on cognition of interferon beta (IFN-β) have been reported and a positive effect from estroprogestins has been hypothesised, suggesting that the combination of the two medications in women with MS could offer a promising treatment strategy. Objectives We investigated whether a combination of estroprogestins and IFN-β can improve cognition in women with MS. Methods Women with relapsing-remitting (RR) MS were randomly assigned (1:1:1) to receive subcutaneous IFN-β-1a (Rebif®, Merck Serono, Geneva, Switzerland) 44 mcg three times a week (tiw) (group 1), subcutaneous IFN-β-1a 44 mcg tiw plus ethinyl estradiol 20 mcg and desogestrel 150 mcg (Mercilon®, MSD Italia SRL, Rome, Italy) (group 2) or subcutaneous IFN-β-1a 44 mcg tiw plus ethinyl estradiol 40 mcg and desogestrel 125 mcg (Gracial®, Organon Italia S.p.A., Rome, Italy) (group 3) in a randomised controlled trial, for which we report the analysis of secondary outcomes. At baseline and at 24 months, all patients underwent magnetic resonance imaging (MRI) and a comprehensive cognitive assessment, including Rao’s Brief Repeatable Battery (RBRB) and questionnaires for depression, fatigue and quality of life. Failure in at least two of the RBRB tests defined ‘cognitive impairment’. Results At baseline, there was no difference in the proportion of cognitively impaired patients. At month 24, the proportion of patients with cognitive impairment was lower in group 3 (34.8%) than in group 1 (47.6%) (p = 0.03). The risk of developing cognitive impairment over 24 months was lower in group 3 (p = 0.02). Mood and fatigue scores were comparable across the groups over time at both time points. However, at month 24, group 3 showed worsening on the sexual function subscale of the 54-item MS quality-of-life questionnaire (p = 0.03). Conclusions This study suggests that the combination of high-dose estroprogestins and IFN-β may have positive effects on cognition. However, the effect of this treatment on sexual function requires caution to be exercised

Augmented Reality: What Motivates Late Millennials towards Fashion Mobile Apps?

Generation Z is expected to be a dominant demographic and economic group. Cyber-waviness, constant reliance on smart devices that allows them to be always connected are among some of their intrinsic characteristics. The combination of this reality with the ever-changing technological environment is compelling retailers to reshape their business strategies, to meet this group desires and expectations and to foster their engagement. Augmented reality (AR) is emerging as a technological solution that pleases both consumers and retailers. This paper aims to answer two main questions: (1) How does generation Z evaluate an AR experience? (2) Which attributes/benefits do they value or not during an AR experience? Drawing on a qualitative methodology – content analysis of 34 interviewees – we discuss six main dimensions the potential customer value of the relationship between them and AR experiences under retailer context.info:eu-repo/semantics/publishedVersio

Paternal Diet Defines Offspring Chromatin State and Intergenerational Obesity

The global rise in obesity has revitalized a search for genetic and epigenetic factors underlying the disease. We present a Drosophila model of paternal-diet-induced intergenerational metabolic reprogramming (IGMR) and identify genes required for its encoding in offspring. Intriguingly, we find that as little as 2 days of dietary intervention in fathers elicits obesity in offspring. Paternal sugar acts as a physiological suppressor of variegation, desilencing chromatin-state-defined domains in both mature sperm and in offspring embryos. We identify requirements for H3K9/K27me3-dependent reprogramming of metabolic genes in two distinct germline and zygotic windows. Critically, we find evidence that a similar system may regulate obesity susceptibility and phenotype variation in mice and humans. The findings provide insight into the mechanisms underlying intergenerational metabolic reprogramming and carry profound implications for our understanding of phenotypic variation and evolution

Analysis of Transaction Logs from National Museums Liverpool

The websites of Cultural Heritage institutions attract the full range of users, from professionals to novices, for a variety of tasks. However, many institutions are reporting high bounce rates and therefore seeking ways to better engage users. The analysis of transaction logs can provide insights into users’ searching and navigational behaviours and support engagement strategies. In this paper we present the results from a transaction log analysis of web server logs representing user-system interactions from the seven websites of National Museums Liverpool (NML). In addition, we undertake an exploratory cluster analysis of users to identify potential user groups that emerge from the data. We compare this with previous studies of NML website users

Digital transformation: A multidisciplinary perspective and future research agenda

Digital transformation has had an unprecedented influence on all sectors of business over the last decade. We are now entering an era characterized by the extensive digital transformation of businesses, society, and consumers. Therefore, digital transformation has become a pivotal focus for organizations across various sectors in recent years. Despite differing scholarly perspectives on the concept and elements of digital transformation, a consensus exists that it significantly impacts consumer decisions and necessitates organizational adaptation. Recent challenges such as the COVID‐19 pandemic have further accelerated the need for digital transformation and its effects on consumers. This necessitates an editorial perspective on this most important topic to establish future research agenda encompassing the various dimensions of digital transformation. The purpose of this editorial perspective is to review research on digital transformation from a multidisciplinary viewpoint and provide insights into several key domains—Internet‐of‐Things, social media, mobile apps, artificial intelligence, augmented and virtual reality, the metaverse, and corporate digital responsibility—that are poised to fuel the pace of digital transformation. Each domain is analyzed through a lens of introduction, role, importance, multifaceted impact, and conclusions. Future research directions are suggested

Anti-EGFR Therapy in Metastatic Small Bowel Adenocarcinoma: Myth or Reality?

Background: Due to the relative rarity of small bowel adenocarcinoma (SBA), prospective trials, helping to guide therapeutic decisions, are lacking and the optimal therapy for advanced SBA is unknown. The role of targeted agents, such as anti\u2013epidermal growth factor receptor (EGFR) and anti\u2013vascular endothelial growth factor (VEGF), is unknown. Patients and Methods: This is a retrospective multicenter observational study that included patients with metastatic SBA treated with anti-EGFR antibodies (cetuximab or panitumumab) \ub1 chemotherapy in the first (I) or second (II) line. Results: Thirteen patients with metastatic SBA, recruited from 5 Italian referral institutions, were included in the present retrospective analysis. All patients received anti-EGFR inhibitors as a single agent or in association with chemotherapy. More common G2 treatment\u2013related side effects were skin reaction (8 patients, 53.8%), hypomagnesemia (6 patients, 46.2%), and diarrhea (8 patients, 61.5%). Grade 3 diarrhea was observed in only 1 patient. Conjunctivitis was not reported in any patients. Grade 4 toxicity was not reported. In the overall population, median progression-free survival was 5.526 months (95% confidence interval [CI]: 3.684-12.467). Median overall survival was 15.86 months (95% CI: 14.43-24.30). Complete response was observed in 15% of patients, partial response in 39% of patients, stable disease in 23% of patients, and progression disease in 15% of patients. Conclusions: In this retrospective analysis, anti-EGFR inhibitors showed to be a suitable addendum to chemotherapy in the I and II line, with an excellent tolerance and safety profile both in I and II line