Evolution of the Nucleoli During Oogenesis in Xenopus Laevis Studied by Electron Microscopy

1972 ◽  
Vol 10 (2) ◽  
pp. 339-367 ◽  
Author(s):  
P. VAN GANSEN ◽  
A. SCHRAM
Keyword(s):  
Xenopus Laevis ◽  
De Novo ◽  
Dna Amplification ◽  
Cellular Growth ◽  
Phase Iii ◽  
Second Phase ◽  
Nucleolar Structure ◽  
Third Phase ◽  
Electron Microscopes ◽  
Germinal Cells

Xenopus laevis tadpoles and toads were killed at several ages. The structure of the nuclei of the germinal cells has been observed by light and electron microscopes. We distinguish 11 successive stages in nucleolar structure: (1) a single, essentially granular nucleolus in the oogonium (10 µm diameter), (2) a reticulated nucleolus in the leptotene oocyte, (3) fragmentation of this nucleolus into a few smaller nucleoli, (4) multiple tiny nucleoli appearing in the cap of the pachytene oocyte, (5) enrichment in the fibrillar constituent of these intra-cap nucleoli, (6) grouped spherical nucleoli, with well segregated granular and fibrillar constituents, as the disintegration of the cap is going on (diplotene A oocyte, 30 µm diameter), (7) dispersion of those nucleoli in the nuclear sap (diplotene B oocyte, 50 µm diameter), (8) formation of long, ribboned nucleoli with multiple DNA-rich spots (diplotene C oocyte, 100 µm diameter), (9) fragmentation of the nucleolar ribbons into multiple spherical nucleoli with excentric fibrillar core and granular cortex (diplotene D oocyte, 150 µm diameter), (10) multiple purely fibrillar nucleoli (diplotene E oocyte, between 150 and 400 µm diameter), and (11) multiple classical nucleoli with concentric fibrillar core and granular cortex (diplotene F oocyte, between 400 and 1000 µm diameter). The multiplication of the nucleoli in Xenopus laevis may occur successively (a) by the fragmentation of the single oogonium nucleolus at the leptotene stage, (b) by de novo formation of nucleolar bodies inside the cap at the pachytene stage, and (c) by the growth of those nucleoli lying free in the nucleolar sap at the early diplotene stage. They evolve into nucleolar ribbons which later on fragment into spherical bodies. Four successive phases during the growth of an oocyte can be distinguished with respect to the ribosomal system. (I) The first phase is characterized by the nucleolar DNA amplification. (II) During the second phase, the multiplication of the nucleoli is going on. Ribosomes are present in the cytoplasm and the rate of cellular growth is very high. (III) During the third phase, the synthesis of rRNAs seem to be repressed while the synthesis of heterogenous small RNAs is going on. Ribosomes are no longer visible in the cytoplasm. The nucleoli are purely fibrillar. The rate of cell growth is lower than in the preceding phase. (IV) During the fourth ( = Duryee lampbrush stages 3-6), or vitellogenic phase, rRNAs are actively synthesized and numerous ribosomes appear in the cytoplasm. The nucleoli have the classical structure and the rate of growth is about the same as during phase III.

Double-Alternation Runway Performance as a Function of Inter- and Intra-Reinforcement Odor Cues

1974 ◽  
Vol 35 (2) ◽  
pp. 787-793 ◽  
Author(s):  
Stephen F. Davis ◽  
Robert E. Prytula ◽  
Wyatt E. Harper ◽  
Howard K. Tucker ◽  
Clarence Lewis ◽  
...  
Keyword(s):  
Phase Iii ◽  
Second Phase ◽  
Goal Measure ◽  
Reinforcement Schedules ◽  
Runway Performance ◽  
Odor Cues ◽  
Double Alternation ◽  
Third Phase ◽  
Three Phase ◽  
Two Phases

Two groups of 12 rats served as Ss in a three-phase investigation into the production and utilization of odor cues in the runway. Both groups were trained under double-alternation patterns of reward-nonreward with one group serving as start-box donor-odorants, while the second group actually traversed the runway. During the first two phases the run- Ss were water-reinforced, and the donor-odorants were food-reinforced. The reinforcement schedules for the run and donor-odorant Ss were positively correlated during the first phase and negatively correlated during the second phase. In the third phase both groups were food reinforced and the reinforcement schedules once again positively correlated. The results indicated that significant double-alternation patterning was shown by the run- Ss only in the goal measure during Phases I and II. However, significant patterning was shown in start, run, and goal measures during Phase III, suggesting the specificity of odor cues to deprivational states.

scholarly journals Design and analysis 5G mobile network model to enhancement high-density subscribers

2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Musa H. Wali ◽  
Ali Khalid Jassim ◽  
Hasan Ma Almgotir
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Mobile Network ◽  
Phase Iii ◽  
Second Phase ◽  
High Data ◽  
Fifth Generation ◽  
Third Phase ◽  
5G Network ◽  
Phase Phase

To obtain a high data rate that is commensurate with the growing demand for internet services, the fifth generation (5G) cellular networks will use the bandwidth beyond 6 GHz, called millimeters waves (mm-waves), to obtain a higher. The first phase (phase I) of the 5G network design for high user density, where the optimized microcells are deployed at carrier frequency 700 MHz with 20 MHz bandwidth. The second phase (phase II) of the design consists of the deployment of microcells which are operating at 3.6 GHz with 100 MHz bandwidth; this phase is planned to cover 200000 users within the province. The third phase (phase III) of the design is represented by the deployment of picocells, which are planned to operate at 26 GHz frequency and bandwidth 500 MHz; this phase is planned to cover 3,500,000 users within the province. Two types of modulation are adopted for the network (orthogonal frequency division multiplexing (OFDM) and 256 quadrature amplitude modulation (QAM)); the overall performance of the network is studied with regards to the percentage of coverage, power overlapping ratio, frequency interference, and quality of service (QoS).

scholarly journals Using Life Cycle Assessment Method for Selecting Optimal Waste Management System in Tehran City

2019 ◽  
Author(s):  
Fahimeh Rahimi ◽  
Farideh Atabi ◽  
Jafar Nouri ◽  
GhasemAli Omrani
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Waste Management ◽  
Assessment Method ◽  
Phase Iii ◽  
Current Status ◽  
Second Phase ◽  
The Third ◽  
Third Phase

Introduction: In Tehran with a population of 9 million currently, about 2.5 million tons municipal solid waste have been producing annually. Materials and Models: In this study by using Life Cycle Assessment (LCA) model an optimal system of waste management of Tehran was recommended. Based on the quantity and quality of waste in Tehran in 2013 and facilities, three scenarios were selected. First, current status (15% compost, 5% recycling and 80% landfill), second, the maximum use of the capabilities of waste of Tehran (70% compost, 20% recycled and 10% landfill ) and third, the optimal scenario according to conditions of Tehran (55% compost, 10% recycling, 5% energy recovery and 30% landfill). The IWM model and WRATE model was used for Phase II and Phase III, respectively. Results: Results of the conducting second Phase showed in compared to the first scenario by the second and third scenario, the amount of emissions was decreased 64% and 72%, respectively. The third phase results showed the third scenario has the lowest environmental impact in chosen six impact groups. Conclusion: Considering the quality and quantity of wastes in Tehran and also the current facilities, conducting the third scenario could be useful for reducing emissions, the external costs and environmental impacts.

PENERAPAN MODEL QUANTUM LEARNING UNTUK MENINGKATKAN HASIL BELAJAR AUTOCAD SISWA KELAS X TEKNIK PEMESINAN SMK NEGERI 1 STABAT

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Abdul Hasan Saragih
Keyword(s):  
Positive Response ◽  
Phase 1 ◽  
First Grade ◽  
Learning Model ◽  
Second Phase ◽  
Phase 2 ◽  
Phase 3 ◽  
The Third ◽  
Third Phase ◽  
Quantum Learning

This classroom research was conducted on the autocad instructions to the first grade of mechinary class of SMK Negeri 1 Stabat aiming at : (1) improving the student’ archievementon autocad instructional to the student of mechinary architecture class of SMK Negeri 1 Stabat, (2) applying Quantum Learning Model to the students of mechinary class of SMK Negeri 1 Stabat, arising the positive response to autocad subject by applying Quantum Learning Model of the students of mechinary class of SMK Negeri 1 Stabat. The result shows that (1) by applying quantum learning model, the students’ achievement improves significantly. The improvement ofthe achievement of the 34 students is very satisfactory; on the first phase, 27 students passed (70.59%), 10 students failed (29.41%). On the second phase 27 students (79.41%) passed and 7 students (20.59%) failed. On the third phase 30 students (88.24%) passed and 4 students (11.76%) failed. The application of quantum learning model in SMK Negeri 1 Stabat proved satisfying. This was visible from the activeness of the students from phase 1 to 3. The activeness average of the students was 74.31% on phase 1,81.35% on phase 2, and 83.63% on phase 3. (3) The application of the quantum learning model on teaching autocad was very positively welcome by the students of mechinary class of SMK Negeri 1 Stabat. On phase 1 the improvement was 81.53% . It improved to 86.15% on phase 3. Therefore, The improvement ofstudent’ response can be categorized good.

Mixed-Methods Evaluation as Scaffold to the Development of a Mobile Health Application to Support the Prescription of Wheelchairs and Postural Support Devices (Preprint)

2020 ◽  
Author(s):  
Adriana Klein ◽  
Roseli de Deus Lopes ◽  
Rodrigo Suigh
Keyword(s):  
Mixed Methods ◽  
Mobile Health ◽  
Second Phase ◽  
The Third ◽  
Evaluation Approach ◽  
Mixed Methods Evaluation ◽  
Usability Tests ◽  
Third Phase ◽  
Postural Support ◽  
Support Devices

BACKGROUND EasySeating is a mobile health (mHealth) app that supports the prescription of wheelchair and postural support devices (WPSD). It can be used by occupational therapists (OT) and physiotherapists (PT) who prescribe WPSD. The app offers a standardization of the prescription procedure, showing images, metrics and details that guide the prescriber to decide on the best equipment. It was developed with an iterative mixed-methods evaluation approach. Objective: The aim of this study was to investigate the processes involved in the prescription of WPSD and to propose, develop and evaluate a mHealth to support OT and PT prescribers. OBJECTIVE The aim of this study was to investigate the processes involved in the prescription of WPSD and to propose, develop and evaluate a mHealth to support OT and PT prescribers. METHODS This study was divided into three phases and was carried out as an iterative process composed of user consulting/testing (using a mixed-methods evaluation approach), system (re)design and software development. The first phase consisted of the collection of qualitative and quantitative data to map and understand the users requirements and of the development of the first prototype (v1) of the app. This data collection was performed through semi-structured interviews with 14 OT and PT prescribers, 5 specialized technicians and 5 WPSD users. The second phase aimed at improving the overall functionality of the app and consisted in the development, test and evaluation of the prototypes v1, v2, v3 and v4. A total of 59 prescribers tested and evaluated these prototypes by means of open interviews, semi-structured questionnaires and focus groups. The third phase focused in the usability aspects of the app. It consisted in the development and test of the prototype v5. Eight technology specialists assessed its usability through heuristics evaluation. RESULTS Data collected in phase one indicated there is a lack of standardization on the prescription of postural support devices (PSD). A divergent nomenclature for the PSDs was also found and classified in eight categories. These information guided the development of the first prototype of the EasySeating app. Phase two results pointed that the prescribers value the insertion of the app into their clinical practice, as it accelerates and increases the quality of the evaluation process and improves the organization of the prescription information. Significant suggestions for the improvement of the app were given during the users tests, including the use of images to represent the PSDs. The usability tests from the third phase revealed two strong issues that must be solved: the need of greater feedback and failures in the persistence of the input data. CONCLUSIONS This study demonstrated that there is a lack of systematization of the WPSD prescription process. The evaluation of the developed EasySeating app demonstrated that there is a potential to standardize, integrate and organize the WPSD prescription information, supporting and facilitating the decision making process of the prescribers. CLINICALTRIAL This study was approved by the Research Ethics Board of the Universidade de São Paulo (registered protocol n°53929516.6.0000.0065) URL - http://plataformabrasil.saude.gov.br/login.jsf

Foucault as Superauthor

2019 ◽  
Vol 29 (2) ◽  
pp. 104-125
Keyword(s):  
Free Speech ◽  
Second Phase ◽  
Contemporary Society ◽  
Sovereign Power ◽  
Ancient Greek ◽  
Main Motivation ◽  
Critical Attitude ◽  
The Third ◽  
Third Phase ◽  
Lecture Courses

Three phases in Foucault’s examination of authorship and free speech were essential to him throughout his life. They can be linked to such texts as the three lectures “What is an Author?” (first phase), “What is Critique?,” and “What is Revolution?” (second phase), and the two lecture courses, “Fearless Speech,” and “The Courage of Truth” (third phase). Initially, Foucault merely describes the founders of discursivity (hence, “superauthors”), among whom he reckoned only Marx and Freud, as the sole alternative to his own conceptualization of the author function, which is exhibited en masse in contemporary society. He then modifies his views on superauthorship by making Kant the paradigm and by linking his own concept of free speech to a Kan-tian critical attitude. However, Foucault claims only the half of Kant’s philosophical legacy that is related to the study of the ontology of the self.The article advances the hypothesis that the sovereign power of speech, which can be found in Marx and Heidegger and in generally in the concept of “superauthorship,” becomes unacceptable for Foucault. During the third phase, the danger of a tyrannical use of free speech compels Foucault to make a number of fruitful but questionable choices in his work. He focuses on a single aspect of free speech in which a speaker is in a weaker position and therefore has to overcome his fear in order to tell the truth. Foucault associates this kind of free speech with the ancient Greek notion of parrhesia, which according to his interpretation means “fearless speech”; however, this reading is not always supported by the ancient Greek sources. Foucault’s deliberations bring him to the radical conclusion that free speech transforms into performative “aesthetics of existence.” Foucault’s main motivation for pursuing this line of thought all through his life was to investigate his own abilities and powers as an author

scholarly journals Structural and Thermodynamic Analysis of the Resistance Development to Pimodivir (VX-787), the Clinical Inhibitor of Cap Binding to PB2 Subunit of Influenza A Polymerase

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1007
Author(s):  
Jiří Gregor ◽  
Kateřina Radilová ◽  
Jiří Brynda ◽  
Jindřich Fanfrlík ◽  
Jan Konvalinka ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Influenza A ◽  
Polymerase Activity ◽  
Second Phase ◽  
Missense Mutations ◽  
Wild Type ◽  
Resistance Development ◽  
Third Phase ◽  
Major Mutation ◽  
Control And Prevention

Influenza A virus (IAV) encodes a polymerase composed of three subunits: PA, with endonuclease activity, PB1 with polymerase activity and PB2 with host RNA five-prime cap binding site. Their cooperation and stepwise activation include a process called cap-snatching, which is a crucial step in the IAV life cycle. Reproduction of IAV can be blocked by disrupting the interaction between the PB2 domain and the five-prime cap. An inhibitor of this interaction called pimodivir (VX-787) recently entered the third phase of clinical trial; however, several mutations in PB2 that cause resistance to pimodivir were observed. First major mutation, F404Y, causing resistance was identified during preclinical testing, next the mutation M431I was identified in patients during the second phase of clinical trials. The mutation H357N was identified during testing of IAV strains at Centers for Disease Control and Prevention. We set out to provide a structural and thermodynamic analysis of the interactions between cap-binding domain of PB2 wild-type and PB2 variants bearing these mutations and pimodivir. Here we present four crystal structures of PB2-WT, PB2-F404Y, PB2-M431I and PB2-H357N in complex with pimodivir. We have thermodynamically analysed all PB2 variants and proposed the effect of these mutations on thermodynamic parameters of these interactions and pimodivir resistance development. These data will contribute to understanding the effect of these missense mutations to the resistance development and help to design next generation inhibitors.

scholarly journals Hand Surgery in Thailand

2021 ◽  
Vol 13 (01) ◽  
pp. 35-41
Author(s):  
Sunyarn Niempoog ◽  
Kiat Witoonchart ◽  
Woraphon Jaroenporn
Keyword(s):  
World War Ii ◽  
Traffic Accidents ◽  
Hand Surgery ◽  
Vital Role ◽  
Second Phase ◽  
World War ◽  
Third Phase ◽  
Foreign Countries ◽  
General Surgeons ◽  
Set Up

AbstractModern hand surgery in Thailand started after the end of World War II. It is divided into 4 phases. In the initial phase (1950-1965), the surgery of the hand was mainly performed by general surgeons. In 1965-1975, which was the second phase, many plastic surgeons and orthopaedic surgeons graduated from foreign countries and came back to Thailand. They played a vital role in the treatment of the surgery of the hand and set up hand units in many centers. They also contributed to the establishment of the “Thai Society for Surgery of the Hand,” which still continues to operate. In the third phase (1975-2000), there was a dramatic development of microsurgery because of the rapid economic expansion. There were many replantation, free tissue transfers, and brachial plexus surgeries in traffic and factory-related accidents. The first hand-fellow training program began in 1993. In the fourth phase (since 2000), the number of hand injuries from factory-related accidents began declining. But the injury from traffic accidents had been increasing both in severity and number. Moreover, the diseases of hand that relate to aging and degeneration had been on the rise. Thai hand surgeons have been using several state-of-the-art technologies such as arthroscopic and endoscopic surgery. They are continuing to invent innovations, generating international publications, and frequently being invited as speakers in foreign countries.

scholarly journals Tacrolimus Once Daily (ADVAGRAF) Versus Twice Daily (PROGRAF) in De Novo Renal Transplantation: A Randomized Phase III Study

2010 ◽  
Vol 10 (12) ◽  
pp. 2632-2643 ◽  
Author(s):  
B. K. Krämer ◽  
B. Charpentier ◽  
L. Bäckman ◽  
H. Tedesco Silva Jr ◽  
G. Mondragon-Ramirez ◽  
...  
Keyword(s):  
Renal Transplantation ◽  
De Novo ◽  
Phase Iii ◽  
Once Daily ◽  
Phase Iii Study

Recrystallization in Ultra-Fine Grain Structures of AA3104 Alloy Processed by ECAP and HPT

2012 ◽  
Vol 715-716 ◽  
pp. 346-353
Author(s):  
H. Paul ◽  
T. Baudin ◽  
K. Kudłacz ◽  
A. Morawiec
Keyword(s):  
High Pressure Torsion ◽  
Deformation Mode ◽  
Second Phase ◽  
Orientation Measurement ◽  
Angular Pressing ◽  
Second Phase Particles ◽  
Average Grain Size ◽  
The Matrix ◽  
Electron Microscopes ◽  
Different Strains

The objective of this study was to determine the effect of deformation mode on recrystallization behavior of severely deformed material. Commercial purity AA3104 aluminum alloy was deformed via high pressure torsion and equal channel angular pressing to different strains and then annealed to obtain the state of partial recrystallization. The microstructure and the crystallographic texture were analysed using scanning and transmission electron microscopes equipped with orientation measurement facilities. The nucleation of new grains was observed in bulk recrystallized samples and during in-situ recrystallization in the transmission microscope. Irrespective of the applied deformation mode, a large non-deformable second phase particles strongly influenced strengthening of the matrix through deformation zones around them. It is known that relatively high stored energy stimulates the nucleation of new grains during the recrystalization. In most of the observed cases, the growth of recrystallized grains occurred by the coalescence of neighboring subcells. This process usually led to nearly homogeneous equiaxed grains of similar size. The diameter of grains in the vicinity of large second phase particles was only occasionally significantly larger than the average grain size. Large grains were most often observed in places far from the particles. TEM orientation mapping from highly deformed zones around particles showed that orientations of new grains were not random and only strictly defined groups of orientations were observed.

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