1,721,004 research outputs found
Pseudo-Hermitian topology in multiband non-Hermitian systems
No full textThe complex eigenenergies and nonorthogonal eigenstates of non-Hermitian systems exhibit unique topological phenomena that cannot appear in Hermitian systems. Representative examples are the non-Hermitian skin effect and exceptional points. In a two-dimensional parameter space, topological classifications of nonseparable bands in multiband non-Hermitian systems can be established by invoking a permutation group, where the product of the permutation represents state exchange due to exceptional points in the space. We unveil in this work the role of pseudo-Hermitian lines in non-Hermitian topology for multiple bands. In particular, the nonseparability of non-Hermitian multibands can be topologically nontrivial without exceptional points in two-dimensional space. As a physical illustration of the role of pseudo-Hermitian lines, we examine a multiband structure of a photonic crystal system with lossy materials. Our work builds on the fundamental and comprehensive understanding of non-Hermitian multiband systems and also offers versatile applications and realizations of non-Hermitian systems without the need to consider exceptional points.
Interobserver Agreement in Ultrasound Risk Stratification Systems for Thyroid Nodules on Static Images Versus Cine-Loop Video Sequences
Full text linkPurpose: To evaluate the impact of video sequences (cine-loops) on the interobserver agreement (IOA) using risk stratification systems (RSSs) for thyroid nodules (TNs). Methods: Twenty TNs were randomly selected from a large database and evaluated by twelve experienced observers using five different RSSs (Kwak-, ACR-, EU-, Korean-TIRADS, ATA Guidelines). In the first step, the evaluation was conducted based on static ultrasound (US) images in two planes (“static”). Six months later, these cases were reevaluated by the same observers using video sequences in two planes (“cine-loops”). Fleiss’ kappa (κ) was calculated for the IOA analyses. Results: IOA on static was moderate with κ values of 0.46, 0.42, 0.40, 0.45, and 0.38 for the Kwak-, ACR-, EU-, Korean-TIRADS, and ATA Guidelines, respectively, while the IOA on cine-loops was fair with κ values of 0.41, 0.38, 0.37, 0.36, and 0.34 for the Kwak-, ACR-, EU-, Korean-TIRADS, and ATA Guidelines, respectively. The overall IOA was superior in static images versus cine-loops (p = 0.024). Among other findings, the subgroup analyses (related to age, gender, US certificates, number of thyroid US per week, and RSSs experience) particularly showed that the experience of the observers in using RSSs had a significant influence on the IOA. Conclusions: The overall IOA (all twelve observers and all five RSSs) was superior on static US images in comparison to cine-loops. Furthermore, the overall IOA of the five US features revealed superior κ values of the static images over cine-loops. However, this impact was significantly lower when the observers were highly experienced in the use of US RSSs of TNs
Diagnosis of Acanthamoeba Keratitis: Past, Present and Future
Full text linkAcanthamoeba keratitis (AK) is a painful and sight-threatening parasitic corneal infection. In recent years, the incidence of AK has increased. Timely and accurate diagnosis is crucial during the management of AK, as delayed diagnosis often results in poor clinical outcomes. Currently, AK diagnosis is primarily achieved through a combination of clinical suspicion, microbiological investigations and corneal imaging. Historically, corneal scraping for microbiological culture has been considered to be the gold standard. Despite its technical ease, accessibility and cost-effectiveness, the long diagnostic turnaround time and variably low sensitivity of microbiological culture limit its use as a sole diagnostic test for AK in clinical practice. In this review, we aim to provide a comprehensive overview of the diagnostic modalities that are currently used to diagnose AK, including microscopy with staining, culture, corneal biopsy, in vivo confocal microscopy, polymerase chain reaction and anterior segment optical coherence tomography. We also highlight emerging techniques, such as next-generation sequencing and artificial intelligence-assisted models, which have the potential to transform the diagnostic landscape of AK
Electro-Stimulation System with Artificial-Intelligence-Based Auricular-Triggered Algorithm to Support Facial Movements in Peripheral Facial Palsy: A Simulation Pilot Study
Full text linkBackground: Facial palsy causes severe functional disorders and impairs quality of life. Disturbing challenges for patients with acute facial palsy, but also with those with chronic facial palsy with synkinesis, are the loss of the ability to smile and insufficient eyelid closure. A potential treatment for these conditions could be a closed-loop electro-stimulation system that stimulates the facial muscles on the paretic side as needed to elicit eye closure, eye blink and smile in a manner similar to the healthy side. Methods: This study focuses on the development and evaluation of such a system. An artificial intelligence (AI)-based auricular-triggered algorithm is used to classify the intended facial movements. This classification is based on surface electromyography (EMG) recordings of the extrinsic auricular muscles, specifically the anterior, superior, and posterior auricular muscle on the paretic side. The system then delivers targeted surface electrical stimulation to contract the appropriate facial muscles. Results: The evaluation of the system was conducted with 17 patients with facial synkinesis, who performed various facial movements according to a paradigm video. The system’s performance was evaluated through a simulation, using previously captured data as the inputs. The performance was evaluated by means of the median macro F1-score, which was calculated based on the stimulation signal (output of the system) and the actual movements the patients performed. Conclusions: This study showed that such a system, using an AI-based auricular-triggered algorithm, can support with a median macro F1-score of 0.602 for the facial movements on the synkinetic side in patients with unilateral chronic facial palsy with synkinesis
Prognostic implications of Ki-67 index and p53, bcl-2 protein expression in primary central nervous system lymphoma
No full text의학과/석사[한글]
중추신경계의 원발성 림프종은 드문 종양으로 두개강내 모든 종양의 1%미만에 불과하나 최근 AIDS 또는 장기이식과 같이 면역결핍상태를 유발할 수 있는 질환과 동반되어 증가하는 추세이며 면역상태가 정상인 사람에서도 증가하고 있다. 대부분의 환자가 방사선, 또는 화학요법 치료에도 불구하고 2년 이내에 사망하지만 이 질환의 예후인자에 대해서는 아직 논란이 많다. 본 연구에서는 수술 또는 생검에 의해 원발성 중추신경계 림프종으로 밝혀진 42명의 환자를 대상으로 임상소견과 병리조직학적소견을 조사하고 35예를 대상으로 p53, bcl-2단백, Ki-67에 대한 면역조직화학염색을 시행하여 환자의 생존률과의 관계를 검사 하였으며 그 결과는 다음과 같다.
1. 원발성 중추신경계 림프종을 Kiel 분류법과 Working formulation에 따라 분류한 결과 저등급(low-grade)이 5예, 중등급(intermediate-grade)이 4예, 고등급(high-grade)이 33예였으며, 면역표현형을 보면 30예는 B세포, 8예는 T세포였다.
2. Ki-67 표지지수는 1.0%에서 92.0%까지 다양하였다(평균 51.1%). 고등급인 경우 61.3%인 반면 저등급에서는 2.0%였고, B세포형은 65.1%인 반면 T세포형에서는 17.5%였으며, 림프종의 등급과 면역표현형에 따라 P값이 각각 0.0002였다.
3. p53 단백은 35예 중 13예(37.1%)에서 발현되었는데 모두 고등급의 B세포림프종이었으며 특히 세포의 면역표현형과는 통계적으로 유의하였다(p=0.02).
4. Bcl-2 단백은 35예 중 18예(51.4%)에서 발현되었지만 종양의 등급이나 면역표현형과는 상관관계가 얼었다.
5. 종양의 등급, 면역표현형 및 Ki-67표지지수 각각에 대하여 Kaplan-Meier 방법으로 생존률과의 관계를 분석한 결과 의미있는 예후인자는 Ki-67 표지지수였다.
이상의 결과로 보아 원발성 중추신경계 림프종 환자의 생존률을 예측하는데 Ki-67 표지지수가 다른 변수에 관계없이 중요하며 따라서 Ki-67 표지지수가 높은 고등급이나 B세포 림프종의 경우 예후가 나쁠 것으로 생각된다. P53과 bcl-2단백의 발현여부와 생존률과는 직접적인 상관이 없었다
[영문]
It has been claimed that CNS lymphoma, a rare neoplasm accounting for only a small fraction of malignant brain tumors, occurs with increasing frequency in immunologically normal as well as immunocompromised individuals. We investigated the prognostic value of Ki-67 index, p53 and bcl-2 oncoprotein expression in relation to clinicopathological parameters in primary CNS lymphoma patients. The tumors were graded by Kiel classification and Working formulation and included 33 high-grade,4 intermediate-grade and 5 low-grade. The phenotype was determined in 38 cases: 30 were B cell type and 8 were T cell type. All cases were found to display variable degrees of nuclear Ki-67 staining from 1.0% to 92.0%(mean 51.1%). A highly significant correlation was established between the proportion of Ki-67 positive cells and the classification into grades(p=0.0002) and phenotypes(p=0.0002).
Overexpression of p53 and bcl-2 protein was found in 37.1% and 51.4% of 35 patients, respectively. And p53 expression is significantly increased in B cell type(p=0.02) . On Kaplan-Meier survival curve, the phenotype and grade of tumors, p53 and bcl-2 protein expression were not correlated with overall survival. On
multivariate analyses, overall survival was independently influenced by Ki-67 index. In conclusion, it is suggested that Ki-67 proliferating index is the most important marker for predicting biologic behavior of primary CNS lymphoma.restrictio
정상 조직 및 유방의 섬유샘종, 엽상종양에서의 anaphase-promoting complex7의 발현
No full textDept. of Medicine/박사[한글]
세포주기에 따른 사이클린(Cyclins)의 단백질 가수 분해는 세포 분열을 위한 기본적인 과정이다. 사이클린 B 단백질 분해는 APC(Anaphase-promoting complex)에 의해 이루어진다. 그러나 증식능이 없는 세포와 조직에서 APC의 발현은 잘 알려지지 않았고, 각 장기의 분화된 세포에서 APC의 발현 여부도 알려지지 않았다. 게다가 APC 발현이상 또는 기능이상에 의한 세포주기의 조절이상은 세포의 형질전환 및 암을 유발할 수 있는데, 인간의 암, 특히 유방의 엽상종양과 같은 기질성 종양(stromal tumor)에서 APC 발현 이상에 관한 보고는 거의 없었다.이러한 문제들을 다루기 위해서, 이 연구는 다양한 정상 조직 혹은 세포, 그리고 유방의 기질세포종양에서의 ACP7 발현에 대해 조사하고, 증식표식자 Ki-67, 합성기 분획(S-phase fraction)과 비교하였다.다양한 정상 조직과 섬유샘종 20예, 소아섬유샘종 20예, 양성 엽상종양 50예, 경계성 엽상종양 20예, 악성 엽상종양 22예로부터 아래와 같은 결과를 얻었다.1) 위장관, 유방 및 타액선의 상피세포, 림프망상계의 림프구와 같은 불안정 세포는 빈번한 APC7과 Ki-67의 발현을 보였다. 이와는 대조적으로 영구세포와 안정세포는 APC7과 Ki-67 발현이 낮거나 거의 없었다.2) APC7과 Ki-67 표지지수의 평균치는 엽상종양군에서 양성에서 악성으로 갈수록 증가했다. 그리고 섬유샘종과 소아섬유샘종의 APC7과 Ki-67의 발현은 엽상종양에서의 발현보다 낮았다.3) 엽상종양군에서 APC7의 발현은 유사분열 수, 세포밀도, 다형성, 기질의 증식 정도와 관련이 있었으나 종양의 크기와는 관련이 없었다.4) 엽상종양군에서 Ki-67의 발현은 유사분열 수, 세포밀도, 다형성, 기질의 증식 정도 그리고 종양의 크기와 관련이 있었다.5) 엽상종양군과 모든 유방 종양에서 APC7 양성 간질세포의 빈도는 Ki-67과 상호 관련이 있었다.6) 유세포 측정기에 의한 합성기 분획값은 엽상종양군이 섬유샘종군 보다 더 높았으며, 합성기 분획값은 Ki-67 지수와 관련이 있었다.위의 결과는 APC7과 Ki-67이 세포증식과 밀접한 관련이 있음을 보여준다. 그러므로 간질세포의 증식을 특징으로 하는 엽상종양은 APC7과 Ki-67 면역조직화학 검사에 의해 그와 유사하게 유사분열 수와 세포밀도가 증가된 섬유샘종과 구별될 것이다. APC7이 Ki-67보다 높은 빈도수로 발현되기 때문에, 섬유샘종으로부터 양성 엽상종양을 구별해내는데 있어 Ki-67 표지지수의 단점을 보완할 수 있다. 게다가 악성 엽상종양에서 다형성이 심한 세포에서 APC7의 발현이 안 되는 소견은 APC7의 소실이 염색체 불안정이나 종양과 관련된 유전자의 변이를 통하여 악성 종양을 유발시키는데 중요함을 시사한다.
[영문]The proteolytic destruction of cyclins is a fundamental process during cell division. Cyclin B proteolysis is triggered by the anaphase-promoting complex (APC). However, the levels and patterns of APC expression in nonproliferating cells and tissue have yet to be determined, and it currently remains unknown as to whether the APC is expressed in differentiated cells from each organ. In addition, cell cycle dysregulation due to APC loss may contribute to cell transformation and human carcinogenesis. There have been only a few reports regarding APC expression in human cancer, particularly in stromal tumors, including phyllodes breast tumors.In order to address these questions, this study investigates APC7 expression in a variety of normal tissues and cells, and in spindle cell breast tumors, and also includes a comparison between the proliferation antigen Ki-67 and S-phase fraction.We selected a representative area in various normal tissues, 20 cases of fibroadenoma, 20 cases of juvenile fibroadenoma, 50 cases of benign phyllodes tumor, 20 cases of borderline phyllodes tumor, and 22 cases of malignant phyllodes tumor.The following results were obtained.1) Labile cells, such as the epithelial cells of the gastrointestinal tract, breast, and salivary gland, and the lymphoid cells of the lymphoreticular system, exhibited frequent expressions of APC7 and Ki-67. However, no or low-level APC7 and Ki-67 expression was noted in permanent and stable cells.2) The average values of the APC7 and Ki-67 labeling indices increased in order from benign to malignant within the phyllodes tumor group, and the fibroadenomas and juvenile fibroadenomas exhibited lower levels of APC7 and Ki-67 expression than did the phyllodes tumors (26.67±13.60% versus 66.07±14.53% and 0.51±0.87% versus 4.29±7.42%, respectively, p=0.000).3) A significant positive correlation was noted between the frequency of APC7 and mitotic count (R=0.32, p=0.002), cellularity (R=0.26, p=0.012), pleomorphism (R=0.34, p=0.001), and degree of stromal overgrowth (R=0.35, p=0.001) in the phyllodes tumor group. APC7 expression was not correlated with tumor size (R=-0.016, p=0.878).4) The Ki-67 expression correlated positively with mitotic count (R=0.632, p=0.000), cellularity (R=0.29, p=0.005), pleomorphism (R=0.53, p=0.000), degree of stromal overgrowth (R=0.46, p=0.000) and tumor size (R=0.25.p=0.015) in phyllodes tumors.5) The frequency of APC7 positive stromal cells correlated with Ki-67 expression in phyllodes tumors (R=0.21, p=0.048), and in all of the examined breast tumors (R=0.303, p=0.000).6) The fibroadenoma group exhibited a lower S-phase fraction than did the phyllodes tumor group (4.19±2.15% versus 6.15±6.05%), but this was determined not to be statistically significant (p=0.163). APC7 expression did not correlate with the S-phase fraction or the G2M fraction. However, Ki-67 expression was correlated positively with the S-phase fraction (R=0.375, p=0.001).The above results indicate that APC7 and Ki-67 are closely related to cell proliferation. Also, phyllodes tumors, which are characterized by the monoclonal proliferation of stromal cells, can be differentiated from cellular fibroadenomas with increased mitotic figures mimicking phyllodes tumors by APC7 and Ki-67 immunochemistry. As APC7 is expressed at higher levels than is Ki-67, it may overcome the limitations of the Ki-67 labeling index with regard to the differentiation of benign phyllodes tumors from fibroadenomas. In addition, considering APC7 loss in highly pleomorphic cells in cases of malignant phyllodes tumors, APC7 downregulation may be associated with sarcomatous transformation via chromosome instability, or accelerated oncogene signaling.ope
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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