Improving Signal To Noise Ratio And Time Resolution For Solid-State Nanopore Measurements

Nanopores have seen broad applicability as single-molecule sensors because of their spatiotemporally localized transduction and high intrinsic gain. In this dissertation, we seek to increase the bandwidths accessible to nanopore measurements through improvements to nanopores, associated measurements electronics, and their integration. Solid-state pores, in particular, can generate signals that are often more than an order of magnitude larger than their biological counterparts. These larger signals make solid-state pores much more amenable to high-bandwidth measurements. Earlier work showed DNA translocation measurements with sub-microsecond temporal resolution using silicon nitride nanopores. In this dissertation, we further improve the temporal resolution to 100 ns by a recently developed CMOS nanopore amplifier (CNP2) with 10 MHz bandwidth capacity using silicon nitride pores thinned with electronic beam techniques to \u3c 3 nm thickness, with pore diameter compatible for ssDNA that hugs the molecules as it translocates. Overall signal-to-noise-ratio-limited bandwidth is optimized through appropriate choice of pore size, salt and bias voltage. To further reduce Cpore, we are passivating silicon-nitride pores with thick dielectrics. We have previously reported on fused-silica based solid state membrane carrying platform which allows us to reduce Cpore to values \u3c 1 pF. We also make use of this versatile, low-capacitance platform to suspend other thin, two-dimensional membrane such as MoS2 to take advantage of the atomic thickness of these 2D materials to increase spatial resolution. In this dissertation, we present data of improvements in DNA translocation recordings in both time resolution and signal to noise ratio (SNR) from combining our custom electronics with these low-capacitance, high-conductance ultra-thin pores. The ultra-low measurement noise allows us to observe an excess current dependent noise due to the pore itself, and the rich dynamics as DNA translocate through the nanopore. We also explore other applications beyond single nanopore such as nanopore arrays and nanoribbon-nanopore devices

Generalize Synchronization Mechanism: Specification, Properties, Limits

Shared resources synchronization is a well studied problem, in both shared memory environment or distributed memory environment. Many synchronization mechanisms are proposed, with their own way to reach certain consistency level. This thesis further found that there is no perfect synchronization mechanism. Each of them has its properties at different level. For example, to enforce strong consistency, writers may loose writing freedom or it would take more time to coordinate. This thesis proposes a framework to generalize all synchronization mechanism in a formal way for better reasoning on properties, from the perspective of multi-writer to single-writer convergence. Therefore, limitations prevent a synchronization mechanism from achieving every property at its optimal level. CAP and ROLL were proposed in previous works to explain such. CAP theorem states that it can only achieve two of Consistency, Availability and Partition tolerance properties. ROLL Theorem uses a framework to model leaderless SMR protocol and states quorum size and fault tolerance are trading off. The thesis covers five properties in a more understandable way to analyze trade-offs and explore new mechanisms.Comment: 17 pages, 1 figure. To be submitted to conferences in 202

Segmenting Taipei’s Real Estate Data – A Cluster Analysis

Data mining has been widely used for knowledge discovery from large amount of data. In this paper, clustering analysis is applied to Taiwan government open data platform (DATA.GOV.TW), segmenting the real estate data so as to understand the real estate market structure in Taiwan. This paper use design science research methodology (DSRM) as research method. The result provides valuable insights into market structures in Taipei City that has limited addressed in past research and contributes to real estate agencies and practitioners an insight-seeking approach that they can follow to generate values from data

Haute couture-to-table? A study of luxury fashion-brand restaurants/Cafés

The significant rise in luxury shopping has recently gained much attention. This paper seeks to better understand the factors involved in luxury consumption. Specifically, a list of 10 luxury fashion-brand restaurants/cafés are identified and used to survey customers’ motivations, perceptions, demographics, and purchase behavior. This study finds that brand equity drivers significantly influence individual’s intention to visit other luxury fashion-brand restaurants/cafés, and purchase products that are associate with the luxury fashion-brand restaurants/cafés where he/she has previously patronized. Female customers show loyalty to luxury fashion brand products and revisit that specific fashion brand restaurants/cafés. These findings enrich and update the existing body of knowledge on luxury-branded restaurants/cafés in relation to customers’ decision making. This study also provides practical implications for luxury fashion-brand F&B owners

Lack of Association Between Total Serum Homocysteine and Extracranial Cerebral Flow

Background/PurposeHigh homocysteine (Hcy) concentration is associated with slow coronary flow. This study examined the association between Hcy and hemodynamic status in the extracranial cerebral arteries in healthy individuals.MethodsA total of 535 healthy adults underwent physical examination and duplex ultrasonography of the extracranial carotid and vertebral arteries, and blood laboratory tests, including biochemistry and serum total Hcy. Flow hemodynamic parameters including velocity, resistance, and volume of the carotid and vertebral arteries were measured. Multiple regression analysis was performed to examine the association between Hcy and the flow parameters.ResultsParticipants with higher Hcy were more likely to have a lower systolic velocity of the internal carotid artery (p = 0.01) and vertebral artery (p < 0.001), and lower resistance of the vertebral artery (p = 0.004). However, the multiple-adjusted means of the flow velocity, resistance, and flow volume of the carotid or vertebral artery were not significantly different across quartiles of Hcy. When Hcy was treated as a continuous variable, there was still no significant relationship between Hcy levels and the aforementioned hemodynamic status.ConclusionOur results did not support the hypothesis that the levels of Hcy are associated with the flow velocity, resistance, and volume of the extracranial cerebral artery in healthy individuals

Therapeutic and Radiosensitizing Effects of Armillaridin on Human Esophageal Cancer Cells

Background. Armillaridin (AM) is isolated from Armillaria mellea. We examined the anticancer activity and radiosensitizing effect on human esophageal cancer cells. Methods. Human squamous cell carcinoma (CE81T/VGH and TE-2) and adenocarcinoma (BE-3 and SKGT-4) cell lines were cultured. The MTT assay was used for cell viability. The cell cycle was analyzed using propidium iodide staining. Mitochondrial transmembrane potential was measured by DiOC6(3) staining. The colony formation assay was performed for estimation of the radiation surviving fraction. Human CE81T/VGH xenografts were established for evaluation of therapeutic activity in vivo. Results. AM inhibited the viability of four human esophageal cancer cell lines with an estimated concentration of 50% inhibition (IC50) which was 3.4–6.9 μM. AM induced a hypoploid cell population and morphological alterations typical of apoptosis in cells. This apoptosis induction was accompanied by a reduction of mitochondrial transmembrane potential. AM accumulated cell cycle at G2/M phase and enhanced the radiosensitivity in CE81T/VGH cells. In vivo, AM inhibited the growth of CE81T/VGH xenografts without significant impact on body weight and white blood cell counts. Conclusion. Armillaridin could inhibit growth and enhance radiosensitivity of human esophageal cancer cells. There might be potential to integrate AM with radiotherapy for esophageal cancer treatment

A Comparative Study on Spin-Orbit Torque Efficiencies from W/ferromagnetic and W/ferrimagnetic Heterostructures

It has been shown that W in its resistive form possesses the largest spin-Hall ratio among all heavy transition metals, which makes it a good candidate for generating efficient dampinglike spin-orbit torque (DL-SOT) acting upon adjacent ferromagnetic or ferrimagnetic (FM) layer. Here we provide a systematic study on the spin transport properties of W/FM magnetic heterostructures with the FM layer being ferromagnetic Co$_{20}$Fe$_{60}$B$_{20}$ or ferrimagnetic Co$_{63}$Tb$_{37}$ with perpendicular magnetic anisotropy. The DL-SOT efficiency $|\xi_{DL}|$, which is characterized by a current-induced hysteresis loop shift method, is found to be correlated to the microstructure of W buffer layer in both W/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ systems. Maximum values of $|\xi_{DL}|\approx 0.144$ and $|\xi_{DL}|\approx 0.116$ are achieved when the W layer is partially amorphous in the W/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ heterostructures, respectively. Our results suggest that the spin Hall effect from resistive phase of W can be utilized to effectively control both ferromagnetic and ferrimagnetic layers through a DL-SOT mechanism

Mycobacterium tuberculosis and M. bovis infection in Feedlot Deer (Cervus unicolor swinhoei and C. nippon taiouanus) in Taiwan

Background/purposeMycobacterium bovis frequently infects wild and farm deer species with tuberculosis. This study investigated mycobacterial infection in two native deer species Cervus unicolor swinhoei (Formosan Sambar, Sambar) and C. nippon taiouanus (Formasan Sika, Sika).MethodsBased on different sampling sources of 19 intradermal tuberculin test (ITT) Sambar, mycobacterial infection and/or species were detected by acid-fast stain, duplex polymerase chain reaction (PCR) and multiplex nested PCR (mnPCR) methods, traditional mycobacterial culture and gross lesion. Blood samples of 167 Sambar deer and 147 Sika deer were then tested by duplex PCR and mnPCR methods to investigate the prevalence of mycobacterial infection. Sequence variations of these mycobacterial species were analyzed as well.ResultsDuplex PCR and mnPCR assays could differentiate between MTBC (M. bovis and M. tuberculosis) and M. avium, as well as between M. bovis and M. tuberculosis, respectively. These PCR methods showed a higher detection rate than traditional culture and matched the gross lesions examined in 19 ITT-examined Sambar. Therefore, the mycobacterial infection in blood samples of 314 deer samples was detected using these PCR methods. Duplex PCR and mnPCR showed an identical prevalence of 16.1% in Sambar and 8.2% in Sika and a significant difference in prevalence between these two deer species. M. bovis and M. tuberculosis were the species detected in feedlot Sambar and Sika. M. tuberculosis was found only and first in Sambar fed in central Taiwan. Sequence analysis revealed diverse genetic variations in M. bovis and M. tuberculosis associated with deer subspecies.ConclusionMultiplex PCR methods were established, and M. bovis and M. tuberculosis were identified in feedlot deer in Taiwan. Sequence variations indicated diverse sources of both mycobacterial species

Correlation between Pineal Activation and Religious Meditation Observed by Functional Magnetic Resonance Imaging

The human brain possesses plenty of functions but little is known about its scientific relationship with mind and spirit. Conferences^1,2^ focused on the connection between science and religion were held very recently in which neuroscientists, Buddhist scholars and Dalai Lama discussed attention, mental imagery, emotion, mind, brain functions and meditation, suggesting religious meditation offers an effective means to investigate the mystery of mind and spirit. In the past decade, scientists struggled to obtain brain mappings for various meditation styles using different brain imaging techniques and stimulating results have been observed^3-17^. In this letter we report that, together with other brain regions, pineal body exhibit significant activation during meditation process, supporting the long lasting speculation that pineal plays an important role in the intrinsic awareness which might concern spirit or soul. Pineal is known as an endocrine organ which produces substrates including melatonin and has been ascribed numerous even mysterious functions but its activation during meditation has never been observed by brain imaging technique. In seventeenth century, based on anatomic observation, Descartes ventured to suggest that pineal serves as the principal seat of the soul^18-20^. Inspired by its geometric center in the brain, physiologists, psychologists, philosophers and religionists have been speculating for centuries about pineal&#x27;s function relevant to spirit and soul. In this study, we chose Chinese Original Quiet Sitting, one style of meditation, to explore this long lasting speculation by functional magnetic resonance imaging technique. Our results demonstrate a correlation between pineal activation and religious meditation which might have profound implications in physiological understanding of the intrinsic awareness