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Ultra-Wideband Power And Low Noise Distributed Amplifiers With Area Reduction Methods
Get PDFUltra-wideband (UWB) amplifiers are essential components of communication systems,radar, and fiber-optic technologies that require a wide bandwidth and minimallatency. Distributed amplifiers (DAs) effectively manage parasitic capacitancesthrough artificial transmission-line structures, offering inherent broadband performance.However, conventional DAs typically consume large silicon areas due tonumerous stages and extensive interconnections, and passives.This thesis introducesincreased transconductance bandwidth with a fully-shunt peaking method in cascodeand compact inductor-based area reduction methods with decreased quality factoroptimization for distributed power amplifiers (DPA) and distributed low-noise amplifiers(DLNA). The proposed DPA achieves an average 13.75 dB gain and stableoutput power with average of 13.69 dBm across a minimum 70 GHz bandwidth.The DLNA has a noise figure below 6 dB with an average gain of 13.6 dB within thesame frequency range. Both designs, implemented in TSMC’s 65-nm bulk CMOStechnology, outperform literature in noise figure, gain, and output power
Long-Term X-Ray Luminosıty And Rotational Evolution Of Accreting Milisecond X-Ray Pulsars Evolution Of Accreting Millisecond X-Ray Pulsars
Get PDFAccreting millisecond X-ray pulsars (AMXPs) are neutron stars in low mass X-raybinaries (LMXBs). They spun-up through mass accretion from their companion. Todate, 26 AMXPs including three transitional millisecond pulsars have been observedwith spin periods shorter than 10 ms. All known AMXPs are transient sources likelyto be in the final stages of the LMXB evolution, showing periodic X-ray pulsesduring their outbursts. It is important to study the rotational evolution of AMXPssince there are uncertainties in the disc-field interaction and torque mechanismsleading these sources to their descendants namely the radio millisecond pulsars.Observations show that the average torques acting on these systems during theirlong-term evolution are spin-down torques. In some conventional models, observedlong-term spin-down behaviour of AMXPs require external spin-down torques, likegravitational radiation, in addition to disc and magnetic dipole torques. In thisthesis, we investigate the torques acting on the AMXPs during their outburst andquiescent states. We use observational data of five AMXPs which have been observedduring more than one outburst and have spin period derivative measurements forboth outburst and quiescent states. We have found that the spin-up torques duringthe shorter outbursts are dominated by the spin-down torques during the muchlonger quiescent states, resulting in a net spin-down in their long-term transientevolution. Our model results are consistent with the observed X-ray luminositiesand rotational properties of these five sources, which indicate that the long-termrotational evolution of AMXPs can be reproduced by the accretion torque, disc(magnetic) torque, and magnetic dipole torque, without invoking any additionalexternal torque mechanisms
Optimized Budget Selection For Local Differential Privacy
Get PDFIn recent years, local differential privacy (LDP) has emerged as a popular privacystandard and received significant attention from academia and the industry. Thereis increasing interest in its deployment in industrial applications, smart homes, andsmart cities. A pivotal problem in LDP is how to select the value of the privacybudget parameter ε, which controls the tradeoff between the strength of privacyprotection and utility loss.In this dissertation, we propose Optimus, a utility-driven and optimization-basedapproach for ε budget selection in LDP. Given a utility constraint, Optimus formulatesthe problem of budget selection as an optimization problem and contains fivesolution methods for finding the minimal ε that satisfies the given constraint. We experimentallyevaluate the five solution methods in Optimus using five popular LDPprotocols, two datasets, and varying utility constraints. We find that the ε budgetsselected by the different methods are consistent, which is important considering thatLDP is randomized and the optimization process is heuristic. Furthermore, we performcomparative analyses regarding the methods’ efficiency and hyperparametersto assist in their future use. To the best of our knowledge, Optimus is the firstwork to provide a quantitative and algorithmic approach to solving the challenge ofε budget selection in LDP.Beside Optimus which is a general approach for utility-driven budget selection in LDP, we also consider the capacity planning problem specifically, as a practicalapplication in smart homes. Since, the main premise of LDP is that data is perturbedto protect privacy, therefore consumption statistics estimated via LDP are inherentlynoisy. When noisy estimates are used for capacity planning, they can lead to falsepositives (false claims of capacity exceedance) or false negatives (actual exceedancesare neglected).To address these concerns, we propose a system called CAPRI for capacity planningand optimized budget selection in smart city applications under LDP. Based ona specified set of conditions (e.g., number of clients, possible consumption values,LDP protocol) and constraints (e.g., false positive probability should be below 0.01),CAPRI is able to determine the ε privacy budget which simultaneously satisfies thedesired constraints and maximizes clients’ privacy. To do so, CAPRI proposes anoptimization-based problem formulation and a search-based solution which relies onLDP simulations. We experimentally validate and demonstrate the effectiveness ofCAPRI using real-world and synthetic datasets, three popular LDP protocols, andvarious constraints and conditions
Bent partitions and Maiorana-McFarland association schemes
No full textThe recently introduced generalized semifield spreads are partitions of Fpm×Fpm, which are constructed from presemifields with a certain property, called right Fpk-linearity. These partitions have similar properties as spreads. In particular, they are bent partitions, hence they yield a large number of bent functions, vectorial bent functions and amorphic association schemes. We show that with a slight change of parameters, we obtain inequivalent bent partitions, non-isomorphic divisible designs, and bent functions with various algebraic degrees. This is in contrast to classical spreads of Fpm×Fpm, which yield bent functions all of which have algebraic degree (p-1)m. We show that with right Fpk-linear presemifields we can obtain a large variety of vectorial dual-bent functions, which yield, not necessarily amorphic, association schemes. We investigate fusions of these association schemes, which reveal information on their inner structure, and may provide a tool to distinguish non-isomorphic association schemes
Investigating the fluorescence in C-dots immobilised on alginate hydrogels-a study on diffusion kinetics and adsorption mechanisms
No full textImmobilisation of fluorescent carbon dots (C-dots) in a hydrogel matrix, such as alginates, prevents fluorescence quenching in bioimaging and biosensing applications. However, critical parameters influencing the fluorescence, including the diffusion kinetics of C-dots and their distribution within the hydrogel matrix, remain unexplored. Herein, we investigated two distinct methods for immobilising C-dots within alginate hydrogel beads: (i) adsorption and (ii) premixing the C-dots prior to hydrogel cross-linking. Our batch adsorption experiments and kinetic model fittings revealed rapid, concentration-dependent diffusion from the external solution to the beads, along with their binding to surface active sites. The rate-determining step was the diffusion into interconnecting layers within the matrix, which impacts both diffusion rates and the overall distribution of C-dots within the beads. The fluorescence signal in the hydrogel matrix from the adsorption method exhibited limited penetration depth compared to the premixed method, which showed a more uniform distribution. We demonstrated that C-dots are well-immobilised and interact effectively with the hydrogel matrix, exhibiting stable fluorescence intensities and improved structural integrity. Our findings provide valuable insights into the interaction and diffusion of C-dots in hydrogel systems and will help advance research on the fluorescence properties of C-dots for bioimaging and bio-sensing applications
Downward nominal wage rigidity and the optimal inflation target
No full textI investigate the welfare maximizing steady-state inflation rate in a heterogeneous-agent New Keynesian model with Downward Nominal Wage Rigidity (DNWR). After matching the annual wage change distribution in the U.S., I demonstrate that DNWR has a significant impact on the economy, particularly when the inflation target is set low. The optimal inflation rate is estimated to be as high as 8.8%, and increasing the inflation target to the optimal level yields a welfare gain of nearly 3.50%. While the results exhibit sensitivity to parameterization, a broad range of calibrations indicates that the optimal inflation rate is consistently above 3%
Novel alginate-hydroxyapatite composite cryogel for bone regeneration
No full textBone tissue engineering requires biomaterials that not only support cell growth and differentiation but also mimic the mechanical and structural properties of native bones. In this study, we developed a novel alginate-hydroxyapatite (HA) composite cryogel using a one-step cryogelation process, where alginate chains were covalently crosslinked via carbodiimide (EDC) chemistry, with HA incorporated to enhance osteoconductivity. The resulting cryogels were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Solid-State Nuclear Magnetic Resonance (13C NMR), water uptake analysis, mechanical testing, scanning electron microscopy (SEM), and Micro-Computed Tomography (µ-CT). In vitro studies with MC3T3-E1 pre-osteoblasts were conducted to evaluate biocompatibility and osteogenic potential. The cryogels exhibited a highly interconnected porous architecture, maintaining mechanical integrity and excellent swelling properties. Structural and chemical analyses confirmed successful crosslinking and uniform distribution of HA. In vitro cytocompatibility studies demonstrated enhanced cell viability and alkaline phosphatase (ALP) activity, indicating the material's ability to support osteogenic differentiation. These results suggest that the developed composite cryogels hold great potential as a platform for bone regeneration applications
Design of high isolation and low actuation voltage micro cantilever RF-MEMS switch for enhanced performance in mm-wave applications
No full textOne of the significant challenges in advancing RF-MEMS switch technology is achieving low actuation voltage and high capacitance ratio, simultaneously. Reducing the structural spring constant and integrating Metal-Insulator-Metal (MIM) capacitors have been recognized as optimal strategies for lowering actuation voltage; while significantly improving the capacitance ratio in RF-MEMS switches. This study aims to design and development of an RF-MEMS shunt switch in which a cantilever microbeam with a MIM capacitor is integrated to enhance the RF performance in mm-wave frequency band. Simulation using COMSOL®, revealed that the actuation voltage, von mises stress, first resonance frequency mode, switch mass, and the spring constant of the designed switch is about 2.3 V, 5.16 MPa, 1352 Hz, 1.62 µg, and 0.017 N.m-1, respectively; which are promising results. The switch's performance was evaluated across a wide frequency range from 1 to 100 GHz using ANSYS HFSS® simulation The simulation results indicate excellent radio frequency characteristics, i.e. isolation of -52 dB across the frequency range of 70 GHz to 75 GHz, with an insertion loss of -1 dB at 73 GHz and capacitance ratio of 142. These results highlight the favorable RF performance of the proposed switch, which is suitable for next-generation mm-wave applications
Intensive parenting of mothers in 11 countries differing in individualism, income inequality, and social mobility
No full textAlthough intensive parenting has been found to be mostly detrimental for both children and parents, less is known about the correlates and sources of this type of parenting. This study aimed to examine associations between mother's primary involvement in caregiving and intensive parenting, as well as their potential sources, thereby focusing on: family social status, characteristics of the national economy (income inequality and social mobility) and culture (individualism-collectivism) in 11 culturally diverse countries. Participants were 2535 mothers of children aged between 6 and 10. Mothers reported on their intensive parenting behaviors, entailing both supportive and undermining aspects of meeting their child's needs, as well as their level of involvement in daily caregiving tasks and the subjective family social status. Hypotheses were tested controlling for country level response style. Results revealed that: mothers who were more often the primary caregiver across daily tasks used more intensive parenting behaviors; high social status mothers were using less child need undermining yet more supportive intensive parenting behaviors, and less frequently served as the primary caregiver for daily tasks; the undermining intensive parenting behaviors related positively to country-level individualism and income inequality, whereas relations with social mobility were mixed
Foreign bank lending during COVID-19
Get PDFWe study whether foreign banks’ exposure to the pandemic in their home countries affected their lending in Türkiye. Although foreign banks issued more loans than domestic banks, the ones with higher exposure to the pandemic decreased their lending significantly: 1 percentage point higher number of deaths per thousand people in their home countries led to an almost 0.5 percent reduction in lending. This reduction was alleviated by the fiscal support provided in their home countries. Our results support an international spillover of the pandemic shock and the implemented fiscal policies via banks