2,402 research outputs found
Comparative genomics on gene and single nucleotide level
No full textBlom J. Comparative genomics on gene and single nucleotide level. Bielefeld: Universitätsbibliothek; 2013
Transferência eletrônica em sistemas moleculares
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2012O presente trabalho apresenta uma análise teórica do fenômeno de transferência eletrônica (ET) para dois sistemas moleculares. Inicialmente é apresentada uma breve introdução sobre o processo de transferência eletrônica, seguida de uma descrição de seu papel em dispositivos fotovoltaicos orgânicos e poliméricos. Prossegue-se com uma descrição detalhada da teoria usada nesta dissertação e das diferentes técnicas computacionais utilizadas para realizar a propagação temporal de pacotes de onda eletrônicos em sistemas moleculares. Dois modelos físicos são investigados pelo formalismo. No primeiro caso apresenta-se uma análise do fenômeno de transferência eletrônica em um sistema doador-aceitador assistido por ponte: dois átomos de berílio atuam como o par doado-aceitador, para os quais a transferência é intermediada por uma estrutura molecular rígida (cadeia de polietileno) C17H36. Examinou-se as consequência para a transferência dos diferentes comprimentos de ligação que conectam doador e aceitador com a ponte, e a variação do número de unidades de etileno na ponte. Os cálculos demonstram a transição entre a transferência de carácter ôhmico e a super-trânsferência, em acordo com outros formalismos. O segundo modelo de estudo consiste de uma cadeia triatômica dinâmica idealizada para a investigação dos efeitos do movimento iônico sobre a dinâmica eletrônica. Fica evidenciado que em frequências nucleares baixas a dinâmica eletrônica é de carácter adiabático. Em contrapartida, frequências maiores conduzem à efeitos de carácter não adiabático.Abstract : This work presents a theoretical analysis of the electron transfer process for two types of molecular systems. It begins with a brief introduction about the electron transfer process, which is followed by a discussion about the relevance of the process to the operation of organic and polymeric photovoltaic devices. In the sequence, the relevant theory is explained in detail, particularly the computational methods that are used to time propagate electronic wavepackets in molecular structures. Two physical models are investigated with the formalism. In the first case, the analysis of the electron transfer mechanism is carried for a donor-acceptor system coupled by a bridge: two beryllium atoms act as the donor-acceptor pair, and the electronic transfer takes place through a rigid molecular structure (polyethylene chain) C17H36. The effects caused by changing bond lengths between donor/acceptor sites and the bridge as well as varying the number of ethylene units in the bridge were investigated. The calculations show a transition of the transfer behaviour from ohmic to super-exchange, in accordance with predictions made by different formalisms. The second model system consists of a tri-atomic dynamic chain, which is thought for studying the effects of the ionic motion on the electronic dynamics. The present study shows that the electronic dynamics is adiabatic at low nuclear frequencies whereas at high nuclear frequencies non-adiabatic effects arise
Esperienza ed evento della verità. Pratica filosofica e astrazione scientifica nel pensiero di A.N. Whitehead
No full textThis article analyzes the relationship between philosophy, experience and event in A.N. Whitehead’s thought. From the critics of the concept of object, the author retraces and describes the peculiar “abstract-concrete dialectic”, at the center of the researches concerning the perceptual experience.
Furthermore, according to Whitehead’s later works, she demonstrates how the philosophical practice is different from all other kinds of science, although it requires science itself because of the co-implication of object and event, abstraction and recognition
Il "Guerrin Meschino" di Gesualdo Bufalino : un'"opra" in versi
No full textGesualdo Bufalino first published Il Guerrin Meschino in 1991 in a non-commercial edition. In 1993, after a deep revision, he re-published his work with publisher Bompiani: the novel has a modified plot, and the author decided to insert three new poems in addition to the opening and closing poems, formerly present in 1991’s edition. This paper, in its entirety supported by handwritten material preserved at Fondazione Gesualdo Bufalino (Comiso), is divided in two parts: the first part illustrates the differences between the first and the second edition, the second part provides a critical edition of the five poems
Energy Loss Analysis of Tandem PV Modules under Realistic Operating Conditions
No full textTo complete the energy transition, a high efficiency for photovoltaic (PV) modules is desirable to reduce the needed material and surface area (per unit of generated electrical energy). The tandem PV technology has the potential to increase the efficiency of PV modules over 30%. In order to design efficient solar cells, a quantification of the different losses is important. Moreover, research in the losses of PV system has resulted in important insights for PV technology.This work introduces a comprehensive model for quantifying the different loss mechanisms in a PV system with tandem cells. The loss analysis model will be added to the PVMD Toolbox, which is a software developed at Photovoltaic Materials and Devices group at Delft University of Technology.This software can be used to simulate the energy yield of a PV system at any given location. In the loss analysis model, 17 losses are defined and divided into four categories (fundamental, optical, electrical and system losses).The developed model will be used to analyse the loss distribution under different operating conditions for four different PV modules. These different modules are a mono-facial crystalline silicon, a bifacial crystalline silicon, a two-terminal perovskite/silicon tandem, and a three-terminal perovskite/silicon tandem module. The design of these modules is based on a >29% efficient perovskite/silicon tandem cell, fabricated by HZB.The loss distribution of every module is simulated for Standard Test Conditions (STC) and for real word conditions at four geographical locations. Generally, we find that modules operating in tropical high irradiance climates have the lowest efficiency. For all locations, the difference in losses compared to STC follow similar trends. When the two-terminal perovskite/silicon module is simulated at STC, the loss distribution of the fundamental, optical, electrical, and system losses are 54.8%, 8.9%, 8.5%, and 0.1%, leaving a DC module efficiency of 27.7%.At real-world operating conditions, various differences can be found. The most significant differences are the thermalization, reflection, and recombination losses, which increase with 1.4%, 1.1%, and 0.5% respectively for the two terminal perovskite/silicon tandem module. Furthermore, the simulated two-terminal module has a higher efficiency than the three-terminal modules for all operatingconditions due to lower mismatch losses.Additionally, this study was able to quantify the fill factor gain for two-terminal devices. Due to spectral variations, there can be a mismatch between the absorbed current in the top cell and bottom cell, which can lead to losses. However, this loss is partially compensated by an increase in fill factor. For example, a current mismatch of 7.0% is reduced to a power mismatch loss of 1.2%, due to an increase in fill factor. Therefore, the power mismatch should be used as an indicator for mismatch losses instead of the current mismatch.Finally, this study simulated different improvements on operating conditions. The results show that solar tracking does not only increase the in-plane irradiance of the PV system, but can also increase the efficiency. For example, dual-axis tracking can increase the efficiency with 1.1%. Also, the gain of active cooling is simulated and quantified. The increase of efficiency when cooling at 20oCcompared to a PV system without cooling is around 0.4%, mostly caused by decrease in emission and recombination losses. Furthermore, the optimal perovskite thickness for real world conditions is found, by simulating different thicknesses for the perovskite layer. The results shows that the optimalthickness under STC (575 nm) is also optimal under real-world operating conditions. Finally, the optimal bandgap energies for reducing the fundamental losses are found for tandem cells. For all conditions (including STC), the optimal bandgap energies for the top and bottom cell are 1.73 and 0.94 eV respectively.Electrical Engineering | Sustainable Energy Technolog
P.1.04 Expression of histone variants H3.3 and H2a.z in the rat brain: Physiopathological and pharmacological implications
No full textIn the overall context of epigenetic modifications in charge of managing genome plasticity and dynamics [1, 2], the role of nucleosomal loading of histone variants is becoming increasingly captivating. Two replication-independent isoforms of histones H3 and H2A, namely H3.3 and H2A.Z, have caught attention because of their involvement in neuronal plasticity processes, cognitive functions and behavioral outcomes. In fact, their incorporation/eviction in nucleosomes and their turnover in neurons influence chromatin accessibility and therefore transcription. H3.3 enrichment at gene bodies and promoters of genes involved in synaptic plasticity was proved to be positively correlated with their expression, while learning-induced H2A.Z eviction in specific genes promotes gene transcription, intervening in memory consolidation processes. H3.3 is encoded by H3f3a and H3f3b independent genes, generating identical proteins, namely H3.3A and H3.3B. Notably, H3f3b gene, but not H3f3a, was proved responsive to neuronal activating stimuli as well as environmental triggers and stressful procedures [3]. H2A.Z hypervariants H2A.Z.1 and H2A.Z.2, encoded respectively by H2afz and H2afv genes, regulate both basal and stimulus-induced neuronal gene expression of independent gene sets [4]. Starting from this evidence, the purpose of this study was to characterize basal expression levels of all genes encoding for the histones variants above mentioned in rodent hippocampus and prefrontal cortex (PFC), two brain regions closely related to brain plasticity, cognition and behavior. Adult male rats (n=7) were sacrificed, their brains removed and dissected. Total RNA extraction was performed, followed by total RNA reverse transcription and Real Time PCR, where specific forward and reverse primer were used for each gene encoding for H3.3 (H3f3a and H3f3b), H2A.Z (H2afz and H2afv) and endogenous control GAPDH. Statistical analysis was performed by means of one-way ANOVA; p<0.05 was considered as a threshold for statistically significant difference. Molecular analyses revealed that, for both hippocampus and PFC, H3f3a mRNA was more expressed at the steady-state compared to H3f3b (p<0.001), as happens for H2afz mRNA, which displays higher levels than H2afv (p<0.001). Moreover, comparing hippocampal and PFC mRNA levels for each variant, H3f3a and H3f3b expression was increased in the hippocampus with respect to the prefrontal cortex (p<0.001), and a comparable outcome was showed for H2afv (p<0.001) but not for H2afz (p>0.05). Our results suggest that 1) differential basal expression levels of genes encoding for H3.3 and H2A.Z may underlie unique gene responsiveness following different stimuli, as previously hypothesized by others [3,4], and this may be crucial in highly-responsive, pathological- and environment-related tissues like hippocampus and PFC; 2) striking lower steady-state expression of H3f3b and H2afv genes might imply a major sensitivity to neuronal inputs compared to their correspondent counterparts; 3) higher expression levels in the hippocampus with respect to the PFC might underpin brain-region specific expression and function for histone variants and their isoforms. Together, these data clear the way for further studies meant at investigating stimulus-dependent regulation of H3.3 and H2A.Z gene isoforms expression and their putative involvement in the physiopathology of brain and its diseases [5]. References [1] Rigillo, G., Vilella, A., Benatti, C., Schaeffer, L., Brunello, N., Blom, J.M.C., Zoli, M., Tascedda, F., 2018. LPS-induced histone H3 phospho(Ser10)-acetylation(Lys14) regulates neuronal and microglial neuroinflammatory response. Brain Behav Immun. https://doi.org/10.1016/j.bbi.2018.09.019. [2] Ottaviani, E., Accorsi, A., Rigillo, G., Malagoli, D., Blom, J.M., Tascedda, F., 2013. Epigenetic modification in neurons of the mollusc Pomacea canaliculata after immune challenge. Brain Res. 1537, 18–26. [3] Maze, I., Wenderski, W., Noh, K.M., Bagot, R.C., Tzavaras, N., Purushothaman, I., Elsässer, S.J., Guo, Y., Ionete, C., Hurd, Y.L., Tamminga, C.A., Halene, T., Farrelly, L., Soshnev, A.A., Wen, D., Rafii, S., Birtwistle, M.R., Akbarian, S., Buchholz, B.A., Blitzer, R.D., Nestler, E.J., Yuan, Z.F., Garcia, B.A., Shen, L., Molina, H,. Allis, C.D., 2015. Critical Role of Histone Turnover in Neuronal Transcription and Plasticity. Neuron, 87(1), 77-94. [4] Dunn, C. J., Sarkar, P., Bailey, E. R., Farris, S., Zhao, M., Ward, J. M., Dudek, S.M., Saha, R. N., 2017. Histone Hypervariants H2A.Z.1 and H2A.Z.2 Play Independent and Context-Specific Roles in Neuronal Activity-Induced Transcription of Arc/Arg3.1 and Other Immediate Early Genes. eNeuro, 4(4), ENEURO.0040–17.2017. http://doi.org/10.1523/ENEURO.0040-17.2017. [5] Benatti, C., Blom, J.M., Rigillo, G., Alboni, S., Zizzi, F., Torta, R., Brunello, N., Tascedda, F., 2016. Disease-Induced Neuroinflammation and Depression. CNS Neurol. Disord. Drug Targets 15, 414–433
A FEW WORDS ABOUT THE TEACHER. IN MEMORY OF THE EXCELLENT TEACHER AND SCIENTIST M.R. SAPIN
No full textM.R. Sapin (1925–2015) was a professor at I.M. Sechenov First Moscow State Medical University, honorary academician of Russian academy of medical sciences (1988), and an outstanding representative of the Moscow anatomical school of the middle of XX – early XXI century. From the very beginning of his medical training, Mikhail Romanovich got interested in anatomy, especially in angiology and lymphology, and later concentrated on its studying. The author of more than 30 text books and guidelines for schools, universities, and colleges, Mikhail Romanovich was the doctoral and thesis advisor of 51 Ph.D. and approximately 70 MD dissertations. M.R. Sapin made a significant contribution to the development of anatomical education providing the departments with a various range of dry and wet specimens. His stunning and effective work as a tutor was highly appreciated by his students and colleagues, Russian and foreign anatomists. M.R. Sapin was the leader of the Laboratory of Functional Anatomy since 1972, president of the International Association of Morphologists (1992–2006), chairman of the expert commission of Higher Attestation Commission (1959–1994), etc. A man of a great willpower, M.R. Sapin faced a lot of obstacles in his life and research work but overcame that all successfully. The article presents the most important facts of anatomist’s career and lifetime.</jats:p
Verslag van het voorgevallene tijdens het hooge opperwater op de Nederlandsche rivieren in den winter van 1919 op 1920
No full textNadat de Rijn op 20 December 1919 tot even beneden den middelbaren zomerstand 1901-1910 (M.R.) was gedaald vertoonde zich op die rivier een sterke en vrij snelle was, waardoor het water te Keulen tot 6m +M.R. bij het einde van het jaar steeg. In de daarop volgende 11 dagen daalde de waterstand tot 1.5m +M.R. om daarna in 5 dagen weder te rijzen tot den zeer hoogen stand van 7m +M.R. Door een aanvankelijk sterken later flauweren val liep de stand weder terug tot 1.5m +M.R. op 30 Januari. Ook op de Maas vertoonden zich twee dicht op elkaar volgende sterke wassen. Bij den aanvang van den eersten was op 19 december stond het water te Maastricht op ruim 1m +M.R. en steeg het in 6 dagen tot 4.37m +M.R.; in de daaropvolgende 9 dagen bleef de stand steeds hoger dan 4m +M.R. en daalde toen tot ongeveer 2m +M.R. op 10 Januari 1920. De tweede was trad op laatsgenoemde datum in waarbij het water oplied tot 4.94m +M.R. op 15 Januari. Het water daalde daarna dadelijk en was op 29 Januari tot ongeveer 2m +M.R. weggevallen. Bij den tweeden was op Rijn en Maas werden de hoogst bekende waterstanden bij open rivieren overtroffen te Keulen met 7 cm en te Maastricht met 2 cm. De rivieren waren ijsvrij.Hoogwaterversla
Seismic prevention and rahabilitation of nonstructural elements. Criteria to define a post-seismic damage analysis procedure
No full textIt reports very briefly the research work, developed by the author during her Doctorate course, about a post-seismic damage analysis procedure for nonstructural elements of framed structure building system
The Ontology of the Causal Basis of Man : To the Theory of Time
No full textIn 2014, Amirbegov Y.M.'s monograph titled "Mechanics of Thinking" or "Ontological Basis of the Subject" was published, which dealt with a philosophical question: the relationship of matter with consciousness and time of our being. But since the monograph duplicated the thesis conceived by the author and did not go beyond the material presented in it, on the advice of the consultant the author of the monograph is preparing its second edition in an expanded version with a new title: " Ontology of Causal Basis of Man", attracting his mentor, the author of "The Theory of Time or Principle of Formation of Matter Forms" Amirbegov M.R., as a co-author of this book,
Adhering to the opinion that matter between past and future temporal conti-nuity of eternity is reduced to nothing and in reality there remains only a causeless "Nothing", the authors of this book from a clean sheet, but with baggage of knowledge about objective forms of being and causeless reality with its possibili-ties, build an unparalleled theoretical model of human integrity, answering the question: what does a man, his sensorium, consciousness, his thinking apparatus and thought itself, why and how? The authors submit this book to the judgment of the reader
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