The role of electron irradiation history in liquid cell transmission electron microscopy.

In situ liquid cell transmission electron microscopy (LC-TEM) allows dynamic nanoscale characterization of systems in a hydrated state. Although powerful, this technique remains impaired by issues of repeatability that limit experimental fidelity and hinder the identification and control of some variables underlying observed dynamics. We detail new LC-TEM devices that improve experimental reproducibility by expanding available imaging area and providing a platform for investigating electron flux history on the sample. Irradiation history is an important factor influencing LC-TEM results that has, to this point, been largely qualitatively and not quantitatively described. We use these devices to highlight the role of cumulative electron flux history on samples from both nanoparticle growth and biological imaging experiments and demonstrate capture of time zero, low-dose images on beam-sensitive samples. In particular, the ability to capture pristine images of biological samples, where the acquired image is the first time that the cell experiences significant electron flux, allowed us to determine that nanoparticle movement compared to the cell membrane was a function of cell damage and therefore an artifact rather than visualizing cell dynamics in action. These results highlight just a subset of the new science that is accessible with LC-TEM through the new multiwindow devices with patterned focusing aides

The ontological basics of perfectionism in designing educational sites

Background and Objectives: The ultimate goal of education is the learner’s growth. Therefore, the main concern of the architects in this field is the educational environment design in accordance with the high goals of educational system. In this study, relying on the opinions of Islamic thinkers in Quranic sciences field, the teachings derived from the Holy Quran and basic components underlying the perfection has extracted. These components have proposed, as the main contents of design criteria and improving the quality of schools and educational places, in three areas of meaning, function and body to help the architects benefit from an efficient design. Materials and Methods: This study has considered as an effective fundamental research, using quantitative-qualitative methodology. The methodology, in beginning, is survey. Then, the validity of the researcher-made questionnaires and the reliability of the variables have been calculated and confirmed through Cronbach's alpha test with a coefficient of 0.764. In addition, Q factor analysis (extracting expert opinions) and R factor analysis (extracting users' interests) were also performed using spss19 software. The specialist’s statistical population includes 25 professors specialized in the fields of Islamic education, educational sciences and architecture. Next, 40 female trade school junior were selected, from Tehran trade schools, as a non-random environmental users sample. Finally, the illustrated questionnaires obtained from the views of the professors were prepared and analyzed. Findings: After 990 minutes of interviews with specialized professors of Shahid Rajaee University, Tehran University, Science and Technology University and Imam Khomeini international University of Qazvin, two-stage coding and extraction of effective categories were done to prepare a researcher-made questionnaire with 40 items. According to the results of the factor analysis, the following three factors have detected; 1- Physical characteristics of educational buildings as a factor of human spiritual excellence, 2- Introversion as an effective factor in human self-knowledge and self-construction, 3- Extroversion as a factor in regulating environmental conditions and natural areas of human perfection from the view of the specialists. Then, the users’ illustrated questionnaires in 9 different educational fields with 3 quality grades, have distributed among users. Conclusion:: The students’ identified needs, regarding the meaning and spiritual growth, "creating peace and security, a sense of satisfaction, increasing thinking power, fostering creativity and increasing responsibility." In the ​​function field, the following issues are supposed to have taken into account: "individualized places, observance of hierarchy, flexibility, social interactions, multifunctional spaces and the cultivation of sensory powers". In the body field, "observance of diversity, attention to details, scalability, beauty and connection with nature" should have given priority in designing the school and campus. Therefore, based on these identified variables, the obtained correlation model of the factors making students' spiritual excellence in school design is specified through: 1- body design with considering growth factor characteristics, 2- human self-knowledge and self-construction, 3- nature and environment. Therefore, considering the important role of the body and especially the characteristics of the school environment in the growth of students' talents, the optimal design of educational environments is clearly effective to make a suitable ground for their spiritual growth. ===================================================================================== COPYRIGHTS©2021 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers. ====================================================================================

Genome Sequence Analysis of Dengue Virus 1 Isolated in Key West, Florida

Dengue virus (DENV) is transmitted to humans through the bite of mosquitoes. In November 2010, a dengue outbreak was reported in Monroe County in southern Florida (FL), including greater than 20 confirmed human cases. The virus collected from the human cases was verified as DENV serotype 1 (DENV-1) and one isolate was provided for sequence analysis. RNA was extracted from the DENV-1 isolate and was used in reverse transcription polymerase chain reaction (RT-PCR) to amplify PCR fragments to sequence. Nucleic acid primers were designed to generate overlapping PCR fragments that covered the entire genome. The DENV-1 isolate found in Key West (KW), FL was sequenced for whole genome characterization. Sequence assembly, Genbank searches, and recombination analyses were performed to verify the identity of the genome sequences and to determine percent similarity to known DENV-1 sequences. We show that the KW DENV-1 strain is 99% identical to Nicaraguan and Mexican DENV-1 strains. Phylogenetic and recombination analyses suggest that the DENV-1 isolated in KW originated from Nicaragua (NI) and the KW strain may circulate in KW. Also, recombination analysis results detected recombination events in the KW strain compared to DENV-1 strains from Puerto Rico. We evaluate the relative growth of KW strain of DENV-1 compared to other dengue viruses to determine whether the underlying genetics of the strain is associated with a replicative advantage, an important consideration since local transmission of DENV may result because domestic tourism can spread DENVs

Rift Valley fever virus (Bunyaviridae: Phlebovirus): an update on pathogenesis, molecular epidemiology, vectors, diagnostics and prevention

Rift Valley fever (RVF) virus is an arbovirus in the Bunyaviridae family that, from phylogenetic analysis, appears to have first emerged in the mid-19th century and was only identified at the begininning of the 1930s in the Rift Valley region of Kenya. Despite being an arbovirus with a relatively simple but temporally and geographically stable genome, this zoonotic virus has already demonstrated a real capacity for emerging in new territories, as exemplified by the outbreaks in Egypt (1977), Western Africa (1988) and the Arabian Peninsula (2000), or for re-emerging after long periods of silence as observed very recently in Kenya and South Africa. The presence of competent vectors in countries previously free of RVF, the high viral titres in viraemic animals and the global changes in climate, travel and trade all contribute to make this virus a threat that must not be neglected as the consequences of RVF are dramatic, both for human and animal health. In this review, we present the latest advances in RVF virus research. In spite of this renewed interest, aspects of the epidemiology of RVF virus are still not fully understood and safe, effective vaccines are still not freely available for protecting humans and livestock against the dramatic consequences of this virus

Common pitfalls and recommendations for using machine learning to detect and prognosticate for COVID-19 using chest radiographs and CT scans

Abstract: Machine learning methods offer great promise for fast and accurate detection and prognostication of coronavirus disease 2019 (COVID-19) from standard-of-care chest radiographs (CXR) and chest computed tomography (CT) images. Many articles have been published in 2020 describing new machine learning-based models for both of these tasks, but it is unclear which are of potential clinical utility. In this systematic review, we consider all published papers and preprints, for the period from 1 January 2020 to 3 October 2020, which describe new machine learning models for the diagnosis or prognosis of COVID-19 from CXR or CT images. All manuscripts uploaded to bioRxiv, medRxiv and arXiv along with all entries in EMBASE and MEDLINE in this timeframe are considered. Our search identified 2,212 studies, of which 415 were included after initial screening and, after quality screening, 62 studies were included in this systematic review. Our review finds that none of the models identified are of potential clinical use due to methodological flaws and/or underlying biases. This is a major weakness, given the urgency with which validated COVID-19 models are needed. To address this, we give many recommendations which, if followed, will solve these issues and lead to higher-quality model development and well-documented manuscripts

Considerations for imaging thick, low contrast, and beam sensitive samples with liquid cell transmission electron microscopy

© 2018 Transmission electron microscopy of whole cells is hindered by the inherently large thickness and low atomic contrast intrinsic of cellular material. Liquid cell transmission electron microscopy allows samples to remain in their native hydrated state and may permit visualizing cellular dynamics in-situ. However, imaging biological cells with this approach remains challenging and identifying an optimal imaging regime using empirical data would help foster new advancements in the field. Recent questions about the role of the electron beam inducing morphological changes or damaging cellular structure and function necessitates further investigation of electron beam-cell interactions, but such comparisons are complicated by variability in imaging techniques used across various studies currently present in literature. The necessity for using low electron fluxes while imaging biological samples requires finding an imaging strategy which produces the strongest contrast and signal to noise ratio for the electron flux used. Here, we experimentally measure and evaluate signal to noise ratios and damage mechanisms between liquid and cryogenic samples of intact cells using multiple electron imaging modalities all on the same instrument and with equivalent beam parameters to standardize the comparison. We also discuss considerations for optimal electron microscopy imaging conditions for future studies on whole cells within liquid environments