1,385 research outputs found
Small class number fields in the family
We study the class number one problem for real quadratic fields
, where is an odd integer. We show that for there is only one such field with class number one and only
one such field with class number two.Comment: 20 pages. Comments are welcom
Uncovering the role of DICER and pericentric heterochromatin expression during spermatogenesis
Male germ cell differentiation is a complex process that includes mitotic proliferation, meiosis and haploid differentiation phase, during which the cell undergoes dramatic morphological changes to produce mature spermatozoa. Male germ cells have unusually diverse transcriptomes that include a broad variety of protein-coding mRNAs and their isoforms, but also a considerable number of noncoding RNAs (ncRNAs). This research focuses on a specific type of ncRNAs, major satellite repeat (MSR) transcripts that originate from the pericentric heterochromatin regions of the chromosomes and their interplay with the endonuclease DICER during mouse spermatogenesis. Using a germ cell-specific Dicer1 knockout mouse model, I showed that DICER is essential for spermatogenesis and male fertility. The deletion of Dicer1 mainly affected haploid male germ cell differentiation and resulted in defective chromatin condensation and nuclear shaping of spermatids, leading to severe oligoasthenoteratozoospermia and infertility. I revealed that MSRs are transcribed during normal spermatogenesis, particularly in meiotic spermatocytes. Interestingly, MSR transcripts were shown to be aberrantly induced in DICER-null spermatocytes. Only those transcripts that originate from the forward strand of MSR DNA were misregulated in the absence of DICER, suggesting a strand-specific function for DICER in vivo. The forward MSR transcripts and DICER were localized to both the cytoplasm and the nucleus, where nuclear DICER was specifically associated with pericentric heterochromatin regions of chromosomes. Moreover, I showed that MSR transcripts are found in complexes with DICER in the testis, and their processing into small RNAs is compromised in Dicer1 knockout mice leading to an elevated level of forward MSR transcripts in meiotic cells. I also provided evidence of epigenetic imbalance of the pericentric heterochromatin and meiotic chromosome missegregation in Dicer1 knockout testes. These results clearly illustrate that DICER is essential for male fertility, and it contributes to the regulation of pericentric heterochromatin during spermatogenesis by direct targeting MSR transcripts. Furthermore, these studies strongly suggest that the expression of pericentric heterochromatin may have a functional role in the regulation of male germ cell differentiation and fertility.DICER ja perisentromeerisen heterokromatiinin ilmentyminen spermatogeneesin aikana
Spermatogeneesissä sukusolut jakautuvat meioottisesti ja erilaistuvat haploideiksi hedelmöityskykyisiksi siittiöiksi. Tämän prosessin aikana ne ilmentävät genomiaan laajasti, ja proteiineja koodaavien RNA:iden lisäksi niiden transkriptomi koostuu myös huomattavasta määrästä ei-koodaavia RNA:ita. Tässä tutkimuksessa keskityttiin tiettyihin ei-koodaaviin RNA-molekyyleihin, jotka ovat peräisin kromosomien perisentromeerisella heterokromatiinialueella sijaitsevista satelliittitoistojaksoista (major satellite repeats, MSR). Erityisesti tutkimuksessa selvitettiin DICERendonukleaasin toimintaa MSR-RNA:iden säätelyssä hiiren spermatogeneesin aikana. Käyttämällä poistogeenistä Dicer1-hiirimallia osoitin, että sukusolujen DICER-proteiinilla on keskeinen merkitys hedelmällisyyden ylläpidossa, sillä Dicer1-geenin poistaminen esti normaalin siittiötuotannon. Varsinkin haploidi erilaistumisvaihe häiriintyi, mikä johti rakenteeltaan epänormaalien siittiöiden muodostukseen. Tutkimukseni paljasti, että MSR-RNA:ita tuotetaan spermatogeneesin aikana etenkin meioottisissa sukusoluissa, ja että Dicer1-poistogeenisen hiiren sukusoluissa MSR-RNA:iden määrä oli huomattavasti kohonnut. Tulosteni mukaan MSR-RNA:t ja DICER sijaitsivat sekä solulimassa että tumassa, ja näytin DICER-proteiinin sitoutuvan perisentromeerisille heterokromatiinialueelle. Lisäksi osoitin, että kiveksessä DICER ja MSR-RNA-molekyylit löytyvät samoista komplekseista, ja että Dicer1-poistogeenisessä hiiressä MSR-RNA:iden prosessointi oli häiriintynyt. Tämä viittaa siihen, että DICER säätelee MSR-RNA-molekyylejä osallistumalla niiden prosessointiin. Lopuksi osoitin, että Dicer1-geenin poistaminen sai aikaan muutoksia sukusolujen heterokromatiinin epigeneettisessä tilassa. Lisäksi Dicer1-geenin poistaminen oli yhteydessä meioottisten jakautumisten häiriöihin ja aneuploidiaan, mikä mahdollisesti johtuu häiriöistä perisentromeerisen heterokromatiinin toiminnassa. Kaiken kaikkiaan tutkimukseni tulokset osoittavat, että DICER-proteiinilla on keskeinen rooli miesten sukusolujen erilaistumisessa ja MSR-RNA:iden säätelyssä. Tulokset myös viittaavat siihen, että perisentromeerinen heterokromatiini on toiminnallisesti tärkeää normaalin siittiötuotannon ja hedelmällisyyden kannalt
The Political Exploitation of Feminine Sensibility in Alphabet of Lust
Kamala Das is one of the great voices of feminine sensibility in the history of Indian English literature. She wrote poetical and non-poetical works on love and sex very openly and frankly. Political issues have also been a concerning matter in the personal as well as political life of Kamala Das. Her poetical or non-poetical works have the source of political issues in the form of feminine exploitation to the core of life in the patriarchal society all over the world. Her literary works have a great source of such exploitation in not only her social views but also in the politics, extending from the local to the upper level of cabinet ministry. The present research paper is trying to explore the political exploitation of the feminine sensibility in her novel, Alphabet of Lust, 1976
Pain and Pleasure in Kamala Das’ My Story
Pain and Pleasure are the two psychological terms, used in English language and literature to show or describe the state of human mind with the perception of occurring incidents in their lives. In the relation of meaning, both of the terms are adversative adjectives to each other but both have the most important elements in the existence of human beings in the absence of each other. Pain describes the dark side of life or mental the state of human sufferings while pleasure is expressed during the mental state of joy and entertainment or light side of the life. Both of the terms have been well expressed in the autobiographical work of Kamala Das, My Story published in February 1973. This paper is going to explore the human state of mind in the most autobiographical work of Kamala Das, the female Keats and Lawrence of Indian English literature
Realization of Delayed Least Mean Square Adaptive Algorithm using Verilog HDL for EEG Signals
An efficient architecture for the implementation of delayed least mean square (DLMS) adaptive filter is presented in this paper. It is shown that the proposed architectures reduces the register complexity and also supports the faster convergence. Compared to transpose form, the direct form LMS adaptive filter has fast convergence but both has most similar critical path. Further it is shown that in most of the practical cases, very small adaptation delay is sufficient enough to implement a direct-form LMS adaptive filter where in normal cases a very high sampling rate is required and also it shows that no pipelining approach is necessary. From the above discussed estimations three different architectures of LMS adaptive filter has been designed. They are, first design comprise of zero delays i.e., with no adaptation delays, second design comprises of only single delay i.e., with only one adaptation delay, and lastly the third design comprises of two adaptation delays. Among all the three designs zero adaptation delay structure gives efficient performance comparatively. Design with zero adaptation delay involves the minimum energy per sample (EPS) and also minimum area compared to other two designs. The aim of this thesis is to design an efficient filter structures to create a system-on-chip (SoC) solution by using an optimized code for solving various adaptive filtering problems in the system. In this thesis our main focus is on interference cancellation in electroencephalogram (EEG) applications by using the proposed filter structures. Modern field programmable gate arrays (FPGAs) have the resources that are required to design an effective adaptive filtering structures. The designs are evaluated in terms of design time, area and delays
Heat transfer in combined convective magnetohydrodynamic motion of nanofluid holding different shapes of nanoparticles in a channel under the influence of heat source
Heat transfer in mixed convection unsteady MHD flow of an incompressible nanofluid in a channel under the influence of heat source is studied. The channel with non-uniform walls temperature is taken in a perpendicular direction with a transverse magnetic field. Based on the substantial boundary conditions, three different flow conditions are examined. The problem is formed in PDEs with substantial boundary conditions. Four different forms of nanoparticles of identical volume fraction are employed in traditional base fluid water (H2O). Solutions for momentum and energy are attained by the perturbation method and examined graphically in different graphs. It is established that viscosity and thermal conductivity are the mainly well-known variables accountable for different results of velocity and temperature. It is also found that increasing heat source leads to an increase in nanofluid velocity and temperature and nano-size particles instance platelet and blade shapes have lesser momentum as related to brick and cylinder size of nanoparticles
Heat transfer in combined convective magnetohydrodynamic motion of nanofluid holding different shapes of nanoparticles in a channel under the influence of heat source
87-98Heat transfer in mixed convection unsteady MHD flow of an incompressible nanofluid in a channel under the influence of heat source is studied. The channel with non-uniform walls temperature is taken in a perpendicular direction with a transverse magnetic field. Based on the substantial boundary conditions, three different flow conditions are examined. The problem is formed in PDEs with substantial boundary conditions. Four different forms of nanoparticles of identical volume fraction are employed in traditional base fluid water (H2O). Solutions for momentum and energy are attained by the perturbation method and examined graphically in different graphs. It is established that viscosity and thermal conductivity are the mainly well-known variables accountable for different results of velocity and temperature. It is also found that increasing heat source leads to an increase in nanofluid velocity and temperature and nano-size particles instance platelet and blade shapes have lesser momentum as related to brick and cylinder size of nanoparticles
CFD analysis of electroviscous effects in pressure-driven flow of electrolyte liquid through an asymmetrically charged non-uniform microfluidic device
The electroviscous effects in the pressure-driven flow of electrolyte liquid
through an asymmetrically charged contraction-expansion (4:1:4) slit
microfluidic device have been investigated numerically. The mathematical model
(i.e., Poisson's, Navier-Stokes, and Nernst-Planck equations) is solved using
the finite element method to obtain the electrical potential, velocity,
pressure, ion concentration fields, excess charge, an induced electric field
strength for the following ranges of parameters: Reynolds number (),
Schmidt number (), inverse Debye length (),
top wall surface charge density (), surface charge ratio
() and contraction ratio (). Results show
that the charge asymmetry at the different walls of the microfluidic device
plays a significant role in the induced electric field development and
microfluidic hydrodynamics. The total potential () and pressure
drop () maximally increase by 197.45\% and 25.46\%, respectively,
with asymmetry of the charge. {The electroviscous correction factor (ratio of
apparent to physical viscosity) maximally increases by 20.85\% (at ,
for ), 25.46\% (at , for ), and 39.13\% (at , for ).}
Further, a simpler analytical model is developed to predict the pressure drop
in electroviscous flow considering asymmetrically charged surface, based on the
Poiseuille flow in the individual uniform sections and pressure losses due to
orifice, estimates the pressure drop 1--2\% within the numerical results. The
robustness of this model enables the use of present numerical results for
design aspects in microfluidic applications.Comment: 44 pages, 15 figure
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