In order to increase the operating speed of a CMOS image sensor (CIS), a new technique of digital correlated double sampling (CDS) is described. In general, the fixed pattern noise (FPN) of a CIS has ...been reduced with the subtraction algorithm between the reset signal and pixel signal. This is because a single-slope analog-to-digital converter (ADC) has been normally adopted in the conventional digital CDS with the reset ramp and signal ramp. Thus, the operating speed of a digital CDS is much slower than that of an analog CDS. In order to improve the operating speed, we propose a novel digital CDS based on a differential difference amplifier (DDA) that compares the reset signal and the pixel signal using only one ramp. The prototype CIS has been fabricated with 0.13 µm CIS technology and it has the VGA resolution of 640 × 480. The measured conversion time is 16 µs, and a high frame rate of 131 fps is achieved at the VGA resolution.
In this paper, a 120 frames per second (fps) low noise CMOS Image Sensor (CIS) based on a Two-Step Single Slope ADC (TS SS ADC) and column self-calibration technique is proposed. The TS SS ADC is ...suitable for high speed video systems because its conversion speed is much faster (by more than 10 times) than that of the Single Slope ADC (SS ADC). However, there exist some mismatching errors between the coarse block and the fine block due to the 2-step operation of the TS SS ADC. In general, this makes it difficult to implement the TS SS ADC beyond a 10-bit resolution. In order to improve such errors, a new 4-input comparator is discussed and a high resolution TS SS ADC is proposed. Further, a feedback circuit that enables column self-calibration to reduce the Fixed Pattern Noise (FPN) is also described. The proposed chip has been fabricated with 0.13 μm Samsung CIS technology and the chip satisfies the VGA resolution. The pixel is based on the 4-TR Active Pixel Sensor (APS). The high frame rate of 120 fps is achieved at the VGA resolution. The measured FPN is 0.38 LSB, and measured dynamic range is about 64.6 dB.
Dental fear and anxiety are known determinants of delaying or avoiding dental care and vary considerably based on factors such as age and gender. However, little is known about dental fear and ...anxiety in racial/ethnic minority populations, which bear a disproportionate burden of poor oral health outcomes. Structural and social pathways responsible for producing these disparities are also understudied. Experiences of racism over the lifecourse may contribute to poor oral health outcomes through a pathway of dental fear and anxiety. This paper aimed to evaluate perceived experiences with racism, dental fear and anxiety, and the utilization of dental services, in the Black Women's Health Study (BWHS), a United States-based prospective cohort.
Analysis of prospective data obtained from a geographic subset of participants in the BWHS was conducted. In 2014, BWHS participants residing in Massachusetts responded to a mailed oral health questionnaire that included the Index of Dental Anxiety and Fear (IDAF-4C+) instrument (N = 484; 69% response rate). Previously collected demographic and health information, along with reported experiences of everyday and lifetime racism, obtained from national BWHS questionnaires between 1995 and 2009, were merged with the Massachusetts-based sub-sample. Associations between high dental anxiety (HDA) (mean IDAF-4C+ score ≥2.5 on the dental fear and anxiety module) and oral health outcomes and perceived racism and HDA were explored via prevalence ratios (PR) calculated using log-binomial regression models, including adjustment for potential confounders.
Reported exposures to everyday racism occurred weekly on average for the top 25% of the sample, while 13% of participants reported exposure to multiple (n = 3) experiences of unfair treatment due to their race over their lifetime. HDA was prevalent among 17.8% of the sample and was significantly associated with indicators of poor oral health status. High exposures to everyday and lifetime experiences of racism were positively associated with HDA (PR = 1.08; 95% CI: 0.90, 1.58 and PR = 1.72; 95% CI: 1.03, 2.88, respectively).
Significant associations between racism and HDA, and between HDA and poor oral health and reduced utilization of dental care were observed. Dental anxiety may be a pathway through which perceived experiences with racism may impact oral health outcomes.
Streptavidin–fluorescent proteins (SA-FPs) are a versatile tool to visualize a broad range of biochemical applications on a fluorescence microscope. Although the avidin–biotin interaction is widely ...used, the use of SA-FPs has not been applied to single-molecule DNA visualization. Here, we constructed 12 bright SA-FPs for DNA staining or labeling reagents. To date, 810 FPs are available, many of which are brighter than organic dyes. In this study, 12 bright FPs were selected to construct SA-FP plasmids covering green to red colors. Their brightness ranges from 40 to 165 mM–1 cm–1. Moreover, SA-FP is brighter than FP itself because streptavidin forms a tetramer complex; thus, four FPs are in a single complex. In addition, FPs often form a dimer or a tetramer, resulting in multiple FPs in a single spot on a microscopic image. This feature is advantageous because multiple fluorescent β-barrels on a single biotin tag provide enough brightness to be easily visualized by epifluorescence microscopy. Using SA-FPs, we visualized DNA backbones, nickase-based optical mapping, and AT-frequency profiling. Finally, we demonstrated the combination of nickase-based optical mapping using SA-FP and AT-frequency profiling.
Abstract
Fluorophore-linked, sequence-specific DNA binding reagents can visualize sequence information on a large DNA molecule. In this paper, we synthesized newly designed TAMRA-linked polypyrrole ...to visualize adenine and thymine base pairs. A fluorescent image of the stained DNA molecule generates an intensity profile based on A/T frequency, revealing a characteristic sequence composition pattern. Computer-aided comparison of this intensity pattern with the genome sequence allowed us to determine the DNA sequence on a visualized DNA molecule from possible intensity profile pattern candidates for a given genome. Moreover, TAMRA-polypyrrole offers robust advantages for single DNA molecule detection: no fluorophore-mediated photocleavage and no structural deformation, since it exhibits a sequence-specific pattern alone without the use of intercalating dyes such as YOYO-1. Accordingly, we were able to identify genomic DNA fragments from Escherichia coli cells by aligning them to the genomic A/T frequency map based on TAMRA-polypyrrole-generated intensity profiles. Furthermore, we showed band and interband patterns of polytene chromosomal DNA stained with TAMRA-polypyrrole because it prefers to bind AT base pairs.
Abstract
In this study, we specifically visualized DNA molecules at their AT base pairs after in vitro phage ejection. Our AT-specific visualization revealed that either end of the DNA molecule could ...be ejected first with a nearly 50% probability. This observation challenges the generally accepted theory of Last In First Out (LIFO), which states that the end of the phage λ DNA that enters the capsid last during phage packaging is the first to be ejected, and that both ends of the DNA are unable to move within the extremely condensed phage capsid. To support our observations, we conducted computer simulations that revealed that both ends of the DNA molecule are randomized, resulting in the observed near 50% probability. Additionally, we found that the length of the ejected DNA by LIFO was consistently longer than that by First In First Out (FIFO) during in vitro phage ejection. Our simulations attributed this difference in length to the stiffness difference of the remaining DNA within the phage capsid. In conclusion, this study demonstrates that a DNA molecule within an extremely dense phage capsid exhibits a degree of mobility, allowing it to switch ends during ejection.
Large DNA molecules are a promising platform for in vitro single-molecule biochemical analysis to investigate DNA-protein interactions by fluorescence microscopy. For many studies, intercalating ...fluorescent dyes have been primary DNA staining reagents, but they often cause photo-induced DNA breakage as well as structural deformation. As a solution, we previously developed several fluorescent-protein DNA-binding peptides or proteins (FP-DBP) for reversibly staining DNA molecules without structural deformation or photo-induced damage. However, they cannot stain DNA in a condition similar to a physiological salt concentration that most biochemical reactions require. Given these concerns, here we developed a salt-tolerant FP-DBP: truncated transcription activator-like effector (tTALE-FP), which can stain DNA up to 100 mM NaCl. Moreover, we found an interesting phenomenon that the tTALE-FP stained DNA evenly in 1 × TE buffer but showed AT-rich specific patterns from 40 mM to 100 mM NaCl. Using an assay based on fluorescence resonance energy transfer, we demonstrated that this binding pattern is caused by a higher DNA binding affinity of tTALE-FP for AT-rich compared to GC-rich regions. Finally, we used tTALE-FP in a single molecule fluorescence assay to monitor real-time restriction enzyme digestion of single DNA molecules. Altogether, our results demonstrate that this protein can provide a useful alternative as a DNA stain over intercalators.
Many kinds of high dynamic range (HDR) CMOS Image Sensors (CIS) have been reported, such as a multiple sampling, a multiple exposure technique, and so on. However, those techniques have some ...disadvantages of noise increasing, large power consumption, and huge chip area. In this paper, a new digital configurable logarithmic counter is described. Since the proposed scheme is easily implemented with a very simple technique, we can reduce power consumption and chip area drastically. Further, the logarithmic counter enhances the dynamic range (DR). The chip which has been fabricated using a 0.13um CIS process has an excellent SNDR at high speed sampling rate.
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