Performance and Analysis of Segmented Multiple Bus Systems.

The dissertation introduces a new class of bus-based systems called the Segmented Multiple Bus System (SMBS). One of the unique characteristics of the SMBS is that it allows the exploitation of memory reference locality even though it is a bus-based nondirect network. This comes from the architectural interconnection feature that the SMBS can be viewed as a large-scale multiple bus system (MBS) that has been partitioned into smaller partitions called segments. Each such segment is in effect a small conventional MBS whose size is chosen so as to avoid bus loading problems. The SMBS overcomes the architectural limitations of bus-based shared memory systems while maintaining their advantages in terms of high degree of fault tolerance, ease of expansion and ease of programming. In addition SMBS\u27s are scalable; unlike conventional MBS\u27s. Another interesting feature of the SMBS is that it supports wormhole routing which is traditionally used in direct network topologies. We develop performance models to study the SMBS with wormhole routing. Ours is the first attempt to adapt wormhole routing to a bus-based nondirect network. In our performance modeling, features of both direct and nondirect networks are incorporated. We include the effect of blocking and pipelining properties of wormhole routing in the analysis. The bus group of each segment is modeled as a flow equivalent service center which represents a load dependent service center. Two performance models, one assuming single flit buffers and the other assuming infinite flit buffers at segment switches, are developed. Using approximate Mean Value Analysis, we evaluate performance in terms of processing efficiency and request response time. We also simulate the two models without applying any approximations. We report comparisons of analytical results with simulation results to support the accuracy and appropriateness of our new and novel performance models. The results demonstrate good match between simulation and analytical results and show good scalability for the SMBS. The approach we adopt in developing the models is comprehensive in the sense that the models incorporate features of both direct and nondirect networks. This makes our models easily adaptable to several other network topologies

Spectrum of Cuscuton Bounce and Cosmological Parameter Inference Using Dark Sirens

Over the last couple of decades, cosmology has become an exciting area to study. Technological developments in both the computational and observational fronts have propelled cosmology into the limelight of modern physics. Since cosmology is the study of the Universe, many areas of physics — such as astronomy, astrophysics, gravitation, fundamental physics, statistical mechanics, and quantum theory — all couple together and present some of the most fascinating puzzles in modern physics in a natural meeting place. In this thesis I will present my research in two very different epochs of our cosmological history. In order to describe my research, I will first provide a brief introduction to cosmology and Einstein's field equations in a cosmological background. I will then review some of the developments in understanding the very early Universe — a cosmological epoch that corresponds to the very first moments of what we believe to be our cosmological history. I will outline the successes and criticisms of the current paradigm, and discuss the status of alternative proposals that could address some of these criticisms. In particular, bouncing cosmologies are an interesting alternative to inflation since they naturally resolve the singularity problem. I will then present my own work on a bouncing cosmology driven by a modification to general relativity called Cuscuton gravity. In particular, I show the prospects of this model for producing initial conditions for the ripples of spacetime at early times are consistent with observational constraints. In the second half of my thesis, I will drastically shift in time to the ``present day'' Universe, only up to about 2 billion years ago, where I will discuss the prospects of using gravitational waves to extract significant information about the previously hidden sectors of the Universe. To be specific, since the gravitational waves emitted when a compact binary system merges provide an opportunity to measure cosmological distances, this information can then be used alongside previous electromagnetic signals to shed new light on cosmological mysteries. In particular, by assuming that the binary mergers and galaxies both come from the same underlying distribution of matter in our Universe, I show that one can use Bayesian inference methods to infer cosmological parameters without making an excessive amount of assumptions

Directed evolution of CRISPR-Cas9 to increase its specificity

The use of CRISPR-Cas9 as a therapeutic reagent is hampered by its off-target effects. Although rationally designed S. pyogenes Cas9 (SpCas9) variants that display higher specificities than the wild-type SpCas9 protein are available, these attenuated Cas9 variants are often poorly efficient in human cells. Here, we develop a directed evolution approach in E. coli to obtain Sniper-Cas9, which shows high specificities without killing on-target activities in human cells. Unlike other engineered Cas9 variants, Sniper-Cas9 shows WT-level on-target activities with extended or truncated sgRNAs with further reduced off-target activities and works well in a preassembled ribonucleoprotein (RNP) format to allow DNA-free genome editing.

The impact of writing on academic performance for medical students

Abstract Background Writing is a useful learning activity that promotes higher-order thinking, but there are limited studies that prove its effectiveness. In previous research, researchers tested the effect of summary writing on students comprehension and found no significant difference from that of re-studying texts. The purpose of this study, therefore, is to expand previous findings and investigate the effect of two types of writing tasks on medical students academic performance, specifically in the transfer of knowledge. Methods An experiment was conducted with 139 medical students from Seoul National University College of Medicine. They were randomly assigned to three study conditions: self-study (SS), expository writing (EW), and argumentative writing (AW) group. Each group studied the given material by the method they were assigned, and they were tested on their comprehension and transfer of knowledge using rote-memory type items and transfer type items respectively. Results The results showed that the two writing groups displayed better performance than the SS group in transfer type items, while there was no difference in scores between the EW and AW group. However, the three groups showed no significant difference in their scores for rote-memory type items. Also, there was a positive correlation between the writing scores and transfer type item scores in the AW group. Conclusions This study provides empirical evidence for writing to be adopted in medical education for greater educational benefits. Our findings indicate that writing can enhance learning and higher-order thinking, which are critical for medical students

CMOS Skin Sensor for Mobile Skin Diagnosis Using an Electronic Cotton Pad

This paper presents a complementary metal-oxide semiconductor (CMOS) skin sensor for detecting hydration, sebum, and ultraviolet (UV) protection. This sensor employs pixels comprising interdigitated capacitors (IDCs) for detecting hydration and a 30 x 24 photodiode (PD) array for detecting UV protection and sebum. The 4 x 8 pixels with IDCs over the PDs are used for area efficiency; they afford reliable detection regardless of the skin contact area and a high sensitivity, which is achieved via pixel merging. For the readout of both IDCs and PDs, a column-parallel multiple-sampling analog front-end and a 9b successive approximation register analog-to-digital converter are integrated. To detect UV protection under different wavelengths of UVA and UVB, we implement the spatiotemporal delta readout of the PDs. Furthermore, a fully characterized, proof-of-concept prototype chip is fabricated using a 110-nm CMOS process. Compared with conventional skin sensors, the proposed sensor exhibits higher sensitivities of 0.25%/min and 2.32%/mL in detecting dehydration rate and sebum levels, respectively. Moreover, the sensor can detect UV protection under UVA and UVB wavelengths. Owing to its core size of 2.32 x 4.65 mm(2), the proposed sensor can potentially be integrated into cotton pads for mobile skin diagnosis

Relationship matters: a qualitative study of medical students' experiences in a learner-driven research program in South Korea

Background Although research experience is important for medical students, it is difficult to develop research skills only through a formal curriculum. To develop research programs that address the authentic needs of students and align with the entirety of the medical school curriculum, a learner-centered approach may be more effective than an instructor-centered approach. This study investigates medical student perspectives on factors that help them develop research competency. Methods Hanyang University College of Medicine in South Korea operates the Medical Scientist Training Program (MSTP) as a supplement to its formal curriculum. Semi-structured interviews were held with 18 students (20 cases) in the program, and qualitative content analysis was performed using the software tool MAXQDA20. Results The findings are discussed in relation to three domains: learner engagement, instructional design, and program development. The students were more engaged when they perceived the program as a new experience, had prior research experience, wanted to make a good impression, and felt a sense of contribution. In terms of instructional design, they positively participated in research when their supervisors respected them, set clear tasks, provided constructive feedback, and invited them into the research community. In particular, the students highly valued relationships with their professors, and these relationships served not only as a main motivating factor in their research participation but also affected their college lives and careers. Conclusions The longitudinal relationship between students and professors has newly emerged in the Korean context as a factor that strengthens student engagement in research and the complementary relationship between formal curriculum and MSTP was highlighted to encourage student engagement in research

Active learning through discussion: ICAP framework for education in health professions

Background The ICAP framework based on cognitive science posits four modes of cognitive engagement: Interactive, Constructive, Active, and Passive. Focusing on the wide applicability of discussion as interactive engagement in medical education, we investigated the effect of discussion when it was preceded by self-study and further investigated the effect of generating questions before discussions. Methods This study was conducted in the second semester of 2018 and was participated in by 129 students majoring in health professions, including medicine, dentistry, veterinary medicine, and nursing. The students were assigned to four different trial groups and were asked to fill out a Subjective Mental Effort Questionnaire after completing each session. Their performance in posttest scores was analyzed using Bonferroni test, and mental effort was analyzed using mediation analysis. Results These results indicated that the self-study and question group had the highest performance and that the lecture and summary group had the lowest performance when comparing the total score. Using the analysis of mental effort, it was confirmed that the relationship between different study conditions and post-test performance was mediated by mental effort during test. Conclusions Our findings support the ICAP framework and provide practical implications for medical education, representing the fact that students learn more when they are involved in active learning activities, such as self-study and question generation, prior to discussions.This work was supported by Research Resettlement Fund, funded by Seoul National University to allow the new faculty to design and develop new teaching and learning paradigms in higher education

The rostroventral part of the thalamic reticular nucleus modulates fear extinction

The thalamus has been implicated in fear extinction, yet the role of the thalamic reticular nucleus (TRN) in this process remains unclear. Here, in mice, we show that the rostroventral part of the TRN (TRNrv) is critically involved in the extinction of tone-dependent fear memory. Optogenetic excitation of TRNrv neurons during extinction learning dramatically facilitated, whereas the inhibition disrupted, the fear extinction. Single unit recordings demonstrated that TRNrv neurons selectively respond to conditioned stimuli but not to neutral stimuli. TRNrv neurons suppressed the spiking activity of the medial part of the dorsal midline thalamus (dMTm), and a blockade of this inhibitory pathway disrupted fear extinction. Finally, we found that the suppression of dMTm projections to the central amygdala promotes fear extinction, and TRNrv neurons have direct connections to this pathway. Our results uncover a previously unknown function of the TRN and delineate the neural circuit for thalamic control of fear memory. © The Author(s) 201911Nsci

A Mapping of Marine Biodiversity Research Trends and Collaboration in the East Asia Region from 1996–2015

Many countries define policies to manage oceans and coastal areas in order to utilize marine ecosystems strategically. When we reviewed the strategies and policies of various countries in relation to ocean sustainability, we found that biodiversity preservation is a key issue for policies related to sustainable marine development. We investigated the research trends and collaboration status of China, Japan and South Korea regarding marine biodiversity through the analysis of scientific articles using bibliometric analysis. The results showed that Japan collaborated the most with other countries compared to China and South Korea. All three countries collaborated with the Organization for Economic Cooperation and Development (OECD) and Association of Southeast Asian Nations (ASEAN) countries frequently. South Korea showed the strongest inter-collaboration amongst China, Japan and South Korea. Microorganism research is a common research topic in China, Japan and South Korea. Each country demonstrated its own prominent research area, such as local region research in China, deep-sea research in Japan and aquaculture research in South Korea

Highly efficient saturated power amplifier with realizable harmonic loading circuits

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