Geometry-induced memory effects in isolated quantum systems: Observations and applications

Memory effects can lead to history-dependent behavior of a system, and they are ubiquitous in our daily life and have broad applications. Here we explore possibilities of generating memory effects in simple isolated quantum systems. By utilizing geometrical effects from a class of lattices supporting flat-bands consisting of localized states, memory effects could be observed in ultracold atoms in optical lattices. As the optical lattice continuously transforms from a triangular lattice into a kagome lattice with a flat band, history-dependent density distributions manifest quantum memory effects even in noninteracting systems, including fermionic as well as bosonic systems in the proper ranges of temperatures. Rapid growth in ultracold technology predicts a bright future for quantum memory-effect systems, and here two prototypical applications of geometry-induced quantum memory effects are proposed: An accelerometer recording the mechanical change rate in a coupled system and a rate-controlled memvalve where the rate of ramping the lattice potential acts as a control of the remnant density in the lattice.Comment: 13 pages, 11 figures, update figures and references. We provided one more application - quantum memory effects atomic memory (QMEAM

EOR USING IONIC LIQUIDS

As the fact goes, oil is not a renewable energy. As this powerful source is gradually depleting, the demand to recover any single possible drop of the reserves is given serious concern. In conjunction, Enhanced Oil Recovery (EOR), which is a third stage of oil recovery that was carried out after secondary recovery, plays an important role in retrieving petroleum more efficiently. In improving the fluid flows, this project works on refining a compatible Ionic Liquids (ILs) in EOR applications. ILs are salts that are in liquid state below 100°C, composed wholly of anions and cations (Divya Nair G, Development of Ionic Liquids as a Novel EOR Agent Master Symposium, 2012). Studies show that long alkyl chain ionic liquids have the potential to decrease the interfacial tension (IFT) of n-alkanes. Reservoir oil residual will be mobilized if the capillary forces are reduced due to the reduction of IFT against crude oil. In this study, the characterization of ILs will be carried out after its synthesis. After that, the best synthesized ILs will be attempted and run for effectiveness of EOR by using core flood test

Utilization Of Antibody-Conjugated Gold Nanoparticles, Dynamic Light Scattering And Sers In Influenza Virus Detection

Influenza A H3N2, H1N1, and influenza B viruses primarily cause winter illness in humans, leading to significant morbidity and mortality in the population of the very young, the elderly, and people with chronic disease. In addition to the regular seasonal epidemics of influenza, influenza pandemics associated with the emergence of new influenza A strains are threatening due to high levels of mortality, social disruption, and economic losses. These novel strains are not affected by the human immunity developed to older strains of influenza, therefore can spread readily and infect a vast number of people. The most recent flu pandemic outbreak was in 2009, in which pandemic swine influenza A H1N1 was transmitted. Thus, an initiative to prevent human infections with new strains of influenza A virus with pandemic potential has been supported by the government and become a focus of many laboratories. The first step in any preventative measures is early detection. Therefore, it is essential to develop a detection platform that is capable of simultaneous multiplexing and exploitable for point-of-care (POC) analysis. Virus culture, nucleic acid testing, and immunoassays are primary detection approaches to confirm acute human influenza virus infection. Nucleic acid testing has great sensitivity and specificity to subtype influenza strains, and high capacity for multiplexed detection. However, it is time and labor intensive, and expensive. Virus isolation is slow, costly, and not feasible for routine diagnostic testing. Immunoassays, in contrast, are known for availability, low-cost, accuracy, and versatility, and therefore have become a centerpiece in diagnostics. Among a number of analytical detection techniques developed for immunoassays, SERS (surface enhanced Raman spectroscopy) biosensing utilizing antibody-conjugated gold nanoparticles (Ab-AuNPs) is a promising virus detection technique providing high sensitivity (down to single molecule detection) and multiplexing (distinction of different strains of a single virus type). Herein a simple, rapid, sensitive AuNP-based immunoassay was developed to quantitatively detect influenza A virus, utilizing dynamic light scattering (DLS) and surface enhanced Raman spectroscopy (SERS). The assay platform was established based on the principle of homogeneous format. Antigen-specific antibodies (Abs) were attached to the surface of gold nanoparticles (AuNPs), rendering the biospecificity for the detection. AuNPs serve as a signal generator or label. A biological sample containing targeted analytes was mixed with Ab-conjugated AuNPs (or AuNP probes); aggregation of nanoparticle was induced in the presence of the analyte(s). The antibody molecules on the particle surface recognized and bound to the analyte via the key-lock like mechanism, cross-linking AuNPs together to form aggregates. The quantification of antigen became the matter of detecting aggregation. The reaction happened in a timely fashion, oftentimes in a few minutes owing to the fast solution phase kinetics. No washing was required; therefore, time and labor were remarkably saved relative to heterogeneous assays. When utilizing this platform, alteration of different antigen-specific antibodies can perform detection of different antigen analytes individually (singleplexing). The combination of multiple types of AuNP probes in one assay allows simultaneously multiplexed detection. In order to ensure the robustness of the assay, optimization for each stage of the platform design was thoroughly studied. The optimal conditions for maintaining the stability of the gold nanoparticles coated with monoclonal antibodies (mAbs) were investigated by varying pH, conjugation chemistry, mAbs concentrations, and blocking reagents. DLS is exploited to monitor the conjugation of the antibodies on AuNPs and verify the aggregate formation of the antigen-induced AuNP probes based on hydrodynamic diameter measurements. The DLS-based immunoassay has been demonstrated as an excellent rapid screening method to evaluate the specificity and affinity of antibody-antigen binding. Comparing to a conventional method for antibody screening (i.e. ELISA), a DLS assay requires only 30 min while it takes 24 h to perform an ELISA. To address the urgent need for multiplexed detection, we have slightly modified the DLS assay to develop a SERS-based homogeneous immunoassay. Namely, Raman reporters and antibody were co-immobilized on the AuNPs to construct ERLs (extrinsic Raman labels). Raman reporters provide distinctive and amplified signal for detection. In order to detect multiple analytes, multiple types of ERLs were separately prepared; each type was a unique combination of one antigen-specific antibody and one Raman reporter. The ERLs were then mixed together and added to the sample. Aggregation was induced upon the introduction of the antigen to the suspension of ERLs on the order of minutes. ERLs of the same type were cross-linked via the antigen specific to the antibody conjugated to the very type of ERLs. The nonspecific ERLs remained unreacted if their antigens were not present in the sample. Once aggregation occurred, the SERS signals provided by the Raman reporters on the reacted ERLs were turned on. AuNPs in the aggregating state were in proximity to each other and created small gaps between them. Raman reporters once trapped in those gaps generated signal for detection. In theory, SERS analysis can be performed in solution but in reality poor plasmonic coupling between antibody-modified AuNP limits the SERS enhancement. However, dehydration of the aggregates reduces interparticle spacing to yield higher SERS signals. Therefore, separation of aggregated ERLs on a well-defined nanoporous membrane was applied to intensify the signal. The conditions for optimal filtration process have been investigated. Preliminary data have shown progress made toward a fully developed configuration for a portable multiplexed, sensitive, and rapid POC detection platform

Effect of patterned sensory enhancement on sit-to-stand movements in people with Parkinson's disease, The

2019 Summer.Includes bibliographical references.Parkinson's disease (PD) is considered an age-related neurologic disorder that causes motor and non-motor disabilities. Patients with PD present different motor characteristics including bradykinesia, reducing muscular strength, weaker motor and postural control, abnormal range of motion and joint torque, and greater variability during movement. These features cause difficulties in patients' activities of daily living and also bring higher fall risks when they do transferred movements, such as sit-to-stand (STS). The purpose of this study was to consider if Patterned Sensory Enhancement (PSE), a neurologic music therapy (NMT) technique might impact sit-to-stand movement with people with PD. Data were collected on fifteen participants who completed sit-to-stand exercises in baseline, PSE music, and no music conditions. Each sit-to-stand movement was divided into three phases: standing, balance, and sitting. Movements were analyzed for duration/time of movements, sum of movement acceleration (standard deviations) of x, y, and z, pitch of movements, and rotation rate (in z). Significant differences were found in sum of acceleration of x, y, and z in all three phases, with means that participants showed less postural control under PSE music condition. Another significant difference was found in fluctuations of the rotation rate (in z) in the sitting phase, with means indicating participants presented less postural control under PSE music condition compared to no music condition. No other significant differences were found. These results are contrary to prior findings and more research is needed to determine the influence of PSE on STS movements

Maximization of Laplace-Beltrami eigenvalues on closed Riemannian surfaces

Let $(M,g)$ be a connected, closed, orientable Riemannian surface and denote by $\lambda_k(M,g)$ the $k$-th eigenvalue of the Laplace-Beltrami operator on $(M,g)$. In this paper, we consider the mapping $(M, g)\mapsto \lambda_k(M,g)$. We propose a computational method for finding the conformal spectrum $\Lambda^c_k(M,[g_0])$, which is defined by the eigenvalue optimization problem of maximizing $\lambda_k(M,g)$ for $k$ fixed as $g$ varies within a conformal class $[g_0]$ of fixed volume $textrm{vol}(M,g) = 1$. We also propose a computational method for the problem where $M$ is additionally allowed to vary over surfaces with fixed genus, $\gamma$. This is known as the topological spectrum for genus $\gamma$ and denoted by $\Lambda^t_k(\gamma)$. Our computations support a conjecture of N. Nadirashvili (2002) that $\Lambda^t_k(0) = 8 \pi k$, attained by a sequence of surfaces degenerating to a union of $k$ identical round spheres. Furthermore, based on our computations, we conjecture that $\Lambda^t_k(1) = \frac{8\pi^2}{\sqrt{3}} + 8\pi (k-1)$, attained by a sequence of surfaces degenerating into a union of an equilateral flat torus and $k-1$ identical round spheres. The values are compared to several surfaces where the Laplace-Beltrami eigenvalues are well-known, including spheres, flat tori, and embedded tori. In particular, we show that among flat tori of volume one, the $k$-th Laplace-Beltrami eigenvalue has a local maximum with value $\lambda_k = 4\pi^2 \left\lceil \frac{k}{2} \right\rceil^2 \left( \left\lceil \frac{k}{2} \right\rceil^2 - \frac{1}{4}\right)^{-\frac{1}{2}}$. Several properties are also studied computationally, including uniqueness, symmetry, and eigenvalue multiplicity.Comment: 43 pages, 18 figure