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Literatura académica sobre el tema "Gain molecules"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Gain molecules"

Amato, I. "Shiny Molecules Gain New Luster". Science 259, n.º 5098 (19 de febrero de 1993): 1122. http://dx.doi.org/10.1126/science.259.5098.1122.

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Philippidis, Alex. "Large Molecules Continue to Gain Favor". Genetic Engineering & Biotechnology News 32, n.º 10 (15 de mayo de 2012): 10–11. http://dx.doi.org/10.1089/gen.32.10.04.

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Scotognella, Francesco. "Multilayer plasmonic photonic structures embedding photochromic molecules or optical gain molecules". Physica E: Low-dimensional Systems and Nanostructures 120 (junio de 2020): 114081. http://dx.doi.org/10.1016/j.physe.2020.114081.

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Hengel, H., K. Burke, D. Kyburz, R. M. Zinkernagel y U. H. Koszinowski. "Peptides control the gain and loss of allele specificity by mutated MHC class I molecules." Journal of Immunology 154, n.º 9 (1 de mayo de 1995): 4557–64. http://dx.doi.org/10.4049/jimmunol.154.9.4557.

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Abstract To analyze the molecular basis of MHC class I allele-restricted peptide recognition, a set of eight Ld/Lq mutants was constructed and tested for peptide recognition by allele-restricted and peptide-specific CTL. The MHC molecules H-2Ld and H-2Lq differ at six amino acid positions (95, 97, 107, 116, 155, 157) located within the alpha 2 domain of the molecule. Both molecules present the lymphocytic choriomeningitis virus (LCMV) nucleoprotein-derived peptide RPQASGVYM and the murine cytomegalovirus (MCMV) pp89-derived peptide YPHFMPTNL to the respective virus-specific CD8+ CTL is a strictly allele-restricted fashion. All mutated MHC class I molecules did still bind the LCMV peptide and seven of eight mutants retained MCMV peptide binding. The exchange Arg-->Trp at position 97 of Lq in pocket C of the peptide binding groove prevented binding of the MCMV ligand and this loss was compensated by the additional exchange of Ile-->Leu in position 95 (pocket F). Within the Lq molecule, single mutations at either position 97 on the floor of the groove or position 155 of the wall sufficed for a gain of LCMV peptide recognition by Ld-restricted CTL. Altogether, six of eight mutants resulted in a gain of recognition by CTL specific for the other allele. Thus, six of the eight mutants lost MHC-restricted recognition and were accepted by both Ld- as well as Lq-restricted CTL when presenting the LCMV peptide. Only one case of simultaneous recognition of the MCMV peptide by both Ld- as well as Lq-restricted CTL was noted. In other mutations, a gain of recognition by Ld-restricted CTL was associated with a loss of recognition of Lq-restricted CTL. Analysis of extracted MCMV peptide from mutant molecules excluded quantitative differences in presented MCMV peptide as a reason for the lack of CTL recognition. Altogether, the results show that, rather than aminoacids at certain residue positions, individual peptides govern MHC allele specificity of CTL recognition.

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STARIKOV, E. B. "WHY DNA ELECTRICAL PROPERTIES CHANGE ON MOLECULAR OXYGEN DOPING: A QUANTUM-CHEMICAL STUDY". Modern Physics Letters B 18, n.º 16 (10 de julio de 2004): 785–90. http://dx.doi.org/10.1142/s0217984904007311.

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A detailed semiempirical quantum-chemical study is reported on homogeneous adenosine-thymidine and guanosine-cytidine base pair steps, both pure ones and their complexes with oxygen molecules. The results of this study help gain detailed insight into physico-chemical mechanisms of electrical conduction control in DNA molecules when doping them with molecular oxygen or related molecules.

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Bethanis, Kostas, Elias Christoforides, Athena Andreou y Elias Eliopoulos. "Molecular Symmetry of Permethylated β-Cyclodextrins upon Complexation". Symmetry 14, n.º 10 (20 de octubre de 2022): 2214. http://dx.doi.org/10.3390/sym14102214.

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The Cn molecular symmetry implicated by the schemes with which cyclodextrins (CDs), the well-known cyclic oligosaccharides, are introduced in the literature, is not valid. Numerous studies have shown that CDs are rather flexible with their macrocycle adopting various conformations that enable the inclusion complexation of guest molecules of various shapes. In this work, the loss and gain of the C7 symmetry of the heptakis (2, 3, 6-tri-O-methyl)-β-CD (TM-β-CD) is investigated by means of its conformation geometrical features in its hydrated form and upon complexation with molecules of different shapes. For this, the crystal structure of the inclusion complex of a bulky guest molecule (giberellic acid) in TM-β-CD is presented for the first time and compared with the previously determined crystal structures of monohydrated TM-β-CD and the inclusion complex of a linear monoterpenoid (geraniol) in TM-β-CD. The structural investigation was complemented by molecular dynamics simulations in an explicit solvent, based on the crystallographically determined models. The crucial role of the guest, in the symmetry gain of the host, reveals a pronounced induced-fit complexation mechanism for permethylated CDs.

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Nam, Ki Hyun. "Molecular Dynamics—From Small Molecules to Macromolecules". International Journal of Molecular Sciences 22, n.º 7 (5 de abril de 2021): 3761. http://dx.doi.org/10.3390/ijms22073761.

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All molecular systems, from small molecules to macromolecules, exhibit specific characteristics for a specific environment and time. In order to gain an accurate understanding of the functions of all types of molecules, studies of their structure and dynamics are essential. Through dynamic studies, using techniques such as spectroscopy, structure determination, and computer analysis, it is possible to collect functional information on molecules at specific times and in specific environments. Such information not only reveals the properties and mechanisms of action of molecules but also provides insights that can be applied to various industries, such as the development of new materials and drugs. Herein, I discuss the importance of molecular dynamics studies, present the time scale of molecular motion, and review techniques for analyzing molecular dynamics.

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Balducci, G., G. Gigli y G. Meloni. "Dissociation energies of the Ga2, In2, and GaIn molecules". Journal of Chemical Physics 109, n.º 11 (15 de septiembre de 1998): 4384–88. http://dx.doi.org/10.1063/1.477041.

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Winata, Anggun. "Enhancing Students' Visual-Spatial Abilities through the Use of Bonat Berakal Media in Understanding Shapes of Molecules". Hydrogen: Jurnal Kependidikan Kimia 11, n.º 1 (15 de febrero de 2023): 40. http://dx.doi.org/10.33394/hjkk.v11i1.6911.

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Students in 10th grade often get low learning outcomes on one of the chemical concepts, the shapes of molecules. Based on the test results, it can be seen that most students have difficulty on understanding and drawing the shapes of molecules. Many students have difficulty drawing shapes of molecules because shapes of molecules cannot be observed directly using the sense of sight, so students cannot project molecular images on their minds. The inability of students to understand molecular drawings in predicting the shape of molecules may be related to spatial visual abilities. The study aimed to investigate the effectiveness of using Bonat berakal media in enhancing tenth-grade students' visual-spatial abilities in understanding shapes of molecules. The students from classes A, B, and C in academic year 2022/2023 at SMAN 1 Tuban participated in the study. The research design was one group pre-test post-test. The instruments used were a teaching module on shapes of molecules and a spatial visual test. The data was analyzed using N-Gain score. The results showed that the pre-test average of students' spatial visual abilities was low but improved to a high category post-test. The study concluded that the use of Bonat berakal media was effective in improving students' visual-spatial abilities in shapes of melecules concepts, as indicated by an N-Gain score of 0.620.

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Belloche, Arnaud. "Exploring molecular complexity in the Galactic Center with ALMA". Proceedings of the International Astronomical Union 13, S332 (marzo de 2017): 383–94. http://dx.doi.org/10.1017/s1743921317007815.

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AbstractThe search for complex organic molecules (COMs) in the ISM has revealed chemical species of ever greater complexity. This search relies heavily on the progress made in the laboratory to characterize the rotational spectra of these molecules. Observationally, the advent of ALMA with its high angular resolution and sensitivity has allowed to reduce the spectral confusion and detect low-abundance molecules that could not be probed before. We present results of the EMoCA survey conducted with ALMA toward the star-forming region Sgr B2(N). This spectral line survey aims at deciphering the molecular content of Sgr B2(N) in order to test the predictions of astrochemical models and gain insight into the chemical processes at work in the ISM. We report on the tentative detection of N-methylformamide, on deuterated COMs, and on the detection of a branched alkyl molecule. Prospects for probing molecular complexity in the ISM even further are discussed at the end.

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Tesis sobre el tema "Gain molecules"

Kim, Kilyoung. "Super Collision Energy Transfer Studies in Single Collisions Between Vibrationally Hot Benzene Like Molecules and Ground State Bath Molecules: The Effect of Physical Properties of Donor and Bath Molecules on Super Collision Energy Transfer". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2497.

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This research is focused on single-collision energy transfer events between highly vibrationally excited benzene-like donor molecules and small bath molecules, CO2 and N2O in the vibrational ground level. Measuring how much energy is transferred from donors to bath molecules was accomplished by probing bath molecules scattered into specific-rotational states using a tunable Δv=0.0003 cm-1 solid state diode laser. The normalized energy transfer probability distribution function, P(E,E'), determined from energy gain information, is very useful in comparing collisional energy transfer efficiency between various collision systems. P(E,E') is also used to investigate the effects of donor and bath physical properties on collisional energy transfer. The first chapter details the C6H5F–CO2 system, which is the basis of a study on the effect of donor fluorination on strong collision energy transfer. The second chapter is about all fluorobenzene–CO2 systems, which investigates the effect of excess vibrational excitation energy of donors on supercollision energy transfer efficiency as well as donor fluorination effect. The third chapter focuses on how the physical properties of bath molecules affect supercollision energy transfer by measuring state-specific energy gain of N2O scattered into 0000, J=59−75. Instead of CO2, N2O was used as a bath molecule with a pyrazine donor to compare energy gain results of bath molecules with somewhat different physical properties. N2O and CO2 are isoelectronic and have similar mass, but N2O has a small dipole moment. Comparison of P(E,E') obtained from pyrazine–CO2, –N2O, –DCl, and –H2O systems helps to elucidate the effect of the bath physical properties on supercollision energy transfer efficiency. The last chapter is dedicated to the extension of the measurement range of N2O energy gain to the mid J states (J=37–75). In this chapter I discuss reliability of P(E,E') obtained from only high J tail as well as the correction of overall energy transfer rate constant.

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Park, Jeongho. "Molecular Beam Epitaxy (MBE) Growth of Rare Earth Doped Gallium Nitride for Laser Diode Application". University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148273402.

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Azarm, Ali, Paul Corkum y Pavel Polynkin. "Optical gain in rotationally excited nitrogen molecular ions". AMER PHYSICAL SOC, 2017. http://hdl.handle.net/10150/626190.

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We pump low-pressure nitrogen gas with ionizing femtosecond laser pulses at 1.5 mu m wavelength. The resulting rotationally excited N-2(+) 2 molecular ions generate directional, forward-propagating stimulated and isotropic spontaneous emissions at 428 nmwavelength. Through high-resolution spectroscopy of these emissions, we quantify rotational population distributions in the upper and lower emission levels. We show that these distributions are shifted with respect to each other, which has a strong influence on the transient optical gain in this system. Although we find that electronic population inversion exists in our particular experiment, we show that sufficient dissimilarity of rotational distributions in the upper and lower emission levels could, in principle, lead to gain without net electronic population inversion.

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Britton, Mathew. "Isolating the gain in the nitrogen molecular cation". Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41238.

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The nitrogen molecular cation is a promising gain medium for the air laser, which could be a powerful tool for remote sensing applications. After nearly a decade of international scientific effort, there are still questions about the gain mechanisms. This thesis explores gain in the nitrogen molecular ion using an experimental configuration that isolates the generation of gain from uncontrolled effects. We use a narrow nitrogen gas jet in vacuum to minimize propagation distance and a probe pulse to measure gain. We first test the role of inelastic scattering during electron recollision as a mechanism to populate the excited state, and we find that it has a small contribution. Then, we measure gain dynamics by varying the probe delay. We measure short- and long-term gain in different conditions. The long-term gain is consistent with the decay of population inversion due to collisions between electrons and ions in the plasma. The decay is modulated due to rotational wave packets in the states of the ion. Rotational coherence decays on the same timescale as the gain due to the incoherent mixing of states. We then introduce an additional non-ionizing pulse that interacts with the ion after ionization. The additional pulse changes the experiment to pump-probe spectroscopy on the ion itself. It can manipulate the rotational wave packets. It can also halt or redirect the emission following the probe pulse by coupling the ground lasing state with a middle state. In both cases, it controls the characteristics of gain and emission at a distance. These interactions highlight the role of the middle state, which is an essential ingredient for gain. Short-term gain appears at low pump intensity when the pump or control pulses overlap the probe pulse. It is consistent with wave mixing due to Raman gain in a V-system.

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Stephens, James M. "Gain characterization and donor molecule production for a proposed chemical laser system". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/31025.

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Panneerselvam, Nishanthi. "Exploring the sequence landscape of the model protein Rop to gain insights into sequence-stability relationship in proteins". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492735031524266.

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Wang, Yifan. "A Gain of Function Senescence Bypass Screen Identifies the Homeobox Transcription Factor DLX2 as a Regulator of ATM-P53 Signaling". Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:26718730.

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Senescence stimuli activate multiple tumor suppressor pathways to initiate cycle arrest and a differentiation program characteristic of senescent cells. We performed a two-stage, gain-of function screen to select for the genes whose enhanced expression can bypass replicative senescence. We uncovered multiple genes known to be involved in p53 and Rb regulation, ATM regulation and two components of the CST complex involved in preventing telomere erosion and additional genes such as REST and FOXO4 that have been implicated in aging. Among the new genes now implicated in senescence we identified DLX2, a Homeobox transcription factor that has been shown to be required for tumor growth, metastasis and associates with poor cancer prognosis. Growth analysis showed that DLX2 expression led to increased cellular replicative lifespan. We found that DLX2 expression inhibited p53 activation, and DLX2 reduced the protein level of upstream activator kinases ATM and DNA-PK. Our data suggest that DLX2 expression reduces the protein components of the TTI1/TTI2/TEL2 complex, a key complex required for the proper folding and stabilization of ATM, DNA-PK and other members of the PIKK family. Over-expression of DLX2 exhibit mutual exclusivity with p53 alteration in cancer patients, suggesting DLX2 may attenuate the p53 pathway during tumor formation. Our functional screen identified novel players that may promote tumorigenesis by regulating the ATM-p53 pathway and senescence.
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Assefa, Kebebew. "Phenotypic and molecular diversity in the Ethiopian cereal, tef [Eragrostis tef (Zucc.) Trotter] : implications on conservation and breeding /". Alnarp : Dept. of Crop Science, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a426-ab.html.

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Shen, Yu. "Neural Mechanisms of Gait Regulation and Olfactory Plasticity in Caenorhabditis elegans". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226051.

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One of the fundamental questions in biological science is to understand how the nervous system functions to generate behavior. The past decades have witnessed much progress in behavioral neuroscience, but it is often challenging to gain mechanistic insights at the molecular and cellular level. The small nervous system and experimental accessibility of the nematode Caenorhabditis elegans offer an opportunity to study neural mechanisms underlying behavior in greater detail. Because many of the genes and proteins are conserved across species, studies in C. elegans provide useful information to the broad research community. In this dissertation, I use the locomotory gait regulation and olfactory aversive learning as two examples to demonstrate that C. elegans neurobiology can offer unique insights into the organization of behavior in more complex organisms. Chapter 2 of this dissertation characterizes a small neuronal circuit that modulates the amplitude of head deflection in C. elegans. C. elegans moves its head rhythmically along the dorsal-ventral axis during forward movement. By quantifying local head curvature, I found the cholinergic SMD neurons facilitate head deflection, whereas the GABAergic RME neurons restrain head deflection. I then examined the calcium dynamics in RME and found the activity is correlated with, but not dependent on, dorsal-ventral head movement. Using a combination of neurophysiological, behavioral and optogenetic approaches, I found that the SMD neurons drive the calcium oscillation in RME via cholinergic neurotransmission. In return, the activated RME releases GABA, tuning down SMD activity via the B-type GABA receptor, and negatively regulates the head bending amplitude. The interaction between SMD and RME contributes to an excitation-inhibition balance in the motor system, which fine-tunes the bending angle and thus optimizes the phase velocity during forward movement. This oscillatory circuit suggests a parsimonious model for a small neural network to regulate the locomotory gait. The SMD motor neurons are also implicated in a sensori-motor circuit underlying olfactory learning. In Chapter 3, I investigate the plasticity of the circuit in pathogen-induced learning behavior. C. elegans learns to avoid the smell of pathogenic bacteria after being infected by the pathogen. I characterize a mutant that displays enhanced olfactory learning, eol-1, isolated from a forward genetic screen. eol-1 acts in the URX sensory neurons to inhibit learning. The protein product of eol-1 has many homologs in eukaryotes, including the mammalian protein Dom3Z implicated in pre-mRNA quality control. Expressing the mouse Dom3z in eol-1-expressing cells fully rescues the learning phenotype in eol-1 mutants, indicating that EOL-1 shares functional similarities with Dom3Z in regulating learning. Mutating the residues that are critical for the enzymatic activity of Dom3Z, and the equivalent residues in EOL-1, abolishes the function of these molecules in learning. These results provide insights into the function of a conserved protein in regulating experience-dependent behavioral plasticity. In summary, this dissertation aims to understand how a small nervous system regulates complex behavior in C. elegans. I show that the neural circuits underlying rhythmic locomotion share common properties, and evolutionarily conserved molecules have similar functions in regulating neural plasticity. Some of the principles uncovered in C. elegans may be generalizable and informative to our understanding of the human brain.

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Rosvall, Ola. "Enhancing gain from long-term forest tree breeding while conserving genetic diversity /". Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5643-6.pdf.

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Libros sobre el tema "Gain molecules"

The molecular biology of Gaia. New York: Columbia University Press, 1996.

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MacLennan, Bruce J. Theoretical and technological advancements in nanotechnology and molecular computation: Interdisciplinary gains. Editado por IGI Global. Hershey, Pa: IGI Global (701 E. Chocolate Avenue, Hershey, Pennsylvania, 17033, USA), 2011.

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Takao, Kumazawa, Kruger Lawrence y Mizumura Kazue, eds. The polymodal receptor: A gateway to pathological pain. Amsterdam: Elsevier, 1996.

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Williams, George Ronald. Molecular Biology of Gaia. Columbia University Press, 1996.

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Kumar Sharma, Mukesh y Pallavi Kaushik, eds. Therapeutic Implications of Natural Bioactive Compounds. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/97898150800251220301.

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This volume is a comprehensive compilation of contributions on the state of art knowledge about bioactive compounds including their sources, isolation methods, biological effects, health benefits and potential applications. These bioactive compounds could serve as alternatives in the prevention or treatment of multifactorial diseases for vulnerable population groups. Chapters in the book incorporate the knowledge based on traditional medicine with recent findings on bioactive molecules and their pharmaceutical implications in neurodegenerative diseases, cancer, COVID 19, diabetes, immunomodulation and farm animal diseases. The book also highlights the latest breakthroughs in the field of screening, characterization, and novel applications of natural bioactive compounds from diverse group of organisms ranging from bacteria, algae, fungi, higher plants, and marine sources. Authors from renowned institutions of India, Japan and China have shared their expertise in the contributed chapters with the goal of enhancing readers knowledge about the significance of use of bioactives in therapeutics and nutraceuticals. It is an informative reference for researchers, professors, graduate students, science enthusiasts, and all those who wish to gain insights into various aspects of bioactive compounds and development of new pharmacological active constituents and nutritional science.

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Wackerhage, Henning, Jonathon Smith y Darren Wisniewski. Molecular exercise physiology. Editado por Neil Armstrong y Willem van Mechelen. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198757672.003.0031.

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Molecular exercise physiology is the study of exercise physiology using molecular biology methods. The development of differentiated cell types is regulated by transcription factors like the muscle-making MyoD that specifies cell type, while others regulate the development of muscle, tendons, and bones. Maternal nutrition and exercise commonly affect embryonic development through epigenetic mechanisms. Adaptation to exercise involves sensor proteins detecting exercise-related signals, the processing of signals by signalling proteins and networks, and the regulation of the actual adaptations by effector proteins. Many sport- and exercise-related traits depend on both common and rare DNA sequence variations, including the muscle mass-increasing myostatin (GDF8) loss-of-function and the haematocrit-increasing EPOR gain-of-function mutations. Additionally, common DNA sequence variations contribute to the inherited variability of development, body height, strength, and endurance. Finally, in addition to ethical concerns, current genetic performance tests only explain a fraction of the variation of sport and exercise-related traits.

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Morawetz, Klaus. Nonequilibrium Quantum Hydrodynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797241.003.0015.

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The balance equations resulting from the nonlocal kinetic equation are derived. They show besides the Landau-like quasiparticle contributions explicit two-particle correlated parts which can be interpreted as molecular contributions. It looks like as if two particles form a short-living molecule. All observables like density, momentum and energy are found as a conserving system of balance equations where the correlated parts are in agreement with the forms obtained when calculating the reduced density matrix with the extended quasiparticle functional. Therefore the nonlocal kinetic equation for the quasiparticle distribution forms a consistent theory. The entropy is shown to consist also of a quasiparticle part and a correlated part. The explicit entropy gain is proved to complete the H-theorem even for nonlocal collision events. The limit of Landau theory is explored when neglecting the delay time. The rearrangement energy is found to mediate between the spectral quasiparticle energy and the Landau variational quasiparticle energy.

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White, P. Lewis y Rosemary A. Barnes. Molecular diagnosis of fungal disease. Editado por Christopher C. Kibbler, Richard Barton, Neil A. R. Gow, Susan Howell, Donna M. MacCallum y Rohini J. Manuel. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198755388.003.0043.

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Molecular techniques to aid in the diagnosis of fungal disease have been in use for over two decades. However, for polymerase chain reaction (PCR) to gain widespread acceptance outside of specialist centres, methodology must be standardized and in line with general microbiological molecular diagnostics assays, yet for infections other than fungal disease. Apart from Aspergillus PCR, standardized methodology is lacking. It is also essential to identify the optimal role for an assay. Whether this is to confirm a specific disease in symptomatic patients or to exclude disease and prevent the unnecessary use of antifungals will, in part, be determined by prevalence, but will also, along with the disease manifestation, dictate specimen choice and subsequent methodological procedure. This chapter will focus on disease processes determining optimal sample types, before concentrating on the clinical validation of molecular tests for the diagnosis of the main causes of invasive fungal disease, concluding with recent developments. The clinical utility of molecular approaches and potential future benefits that can address emerging issues, such as azole resistance, will also be discussed.

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Farghaly, Samir A., ed. Ovarian Cancer Immunotherapy. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190248208.001.0001.

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Ovarian Cancer Immunotherapy provides a broad overview of several aspects of basic sciences and clinical and therapeutic aspects of immunotherapy for ovarian cancer, as well as state-of-the-art information on molecular genetics and biology. Chapters are written by a team of expert contributors from around the world and explore topics such as antibody therapeutics for ovarian carcinoma, emerging serum biomarkers, ovarian cancer immunity, adoptive cell immunotherapy, the biology of dendritic cells, the role of growth factors, and more. Readers will also gain a better understanding of the molecular and cellular events that underlie ovarian cancer immunology. This book is an ideal reference for clinicians and medical students caring for patients with ovarian cancer, including attending surgeons and physicians, and clinical fellows and residents in the disciplines of gynecologic oncology, medical oncology, and surgical oncology.

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Flynn, Brigid, Natalia S. Ivascu, Vivek K. Moitra, Brigid Flynn y Alan Gaffney, eds. Cardiothoracic Critical Care. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780190082482.001.0001.

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Practicing critical care entails understanding human physiology, pharmacokinetics, and molecular pathways in concert with adherence to evidence-based literature. Some may say combining all of these entities into practice creates the “art” of critical care medicine. One strategy to gain proficiency in the practice of critical care medicine is to simulate what you would do in specific problem-based scenarios. That is the aim of this textbook, with each chapter asking aptly “What Do You Do Now?” This text focuses on cardiothoracic critical care and covers guidelines for evidence-based practice, respiratory and metabolic physiology, common hemodynamic perturbations, ventricular failure, and mechanical circulatory support devices. All clinicians who care for cardiothoracic patients who are critically ill can find pearls of practice wisdom complemented by literature citations within this text. So go ahead, place yourself at the foot of the bed and try to think through “What Do You Do Now?” when presented with each patient within these pages of your handheld cardiothoracic intensive care unit.

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Capítulos de libros sobre el tema "Gain molecules"

Pustovit, Vitaliy, F. Capolino y A. Aradian. "Unified Theoretical Model of Loss Compensation and Energy Transfer for Plasmonic Nanoparticles Coated with a Shell of Active Gain Molecules". En NATO Science for Peace and Security Series B: Physics and Biophysics, 389–90. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-5313-6_27.

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Guelachvili, G. "112 Ga2N (GaNGa)". En Linear Triatomic Molecules, 262–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-74187-9_45.

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Stenholm, Stig. "Absorption and Gain Spectra". En Springer Handbook of Atomic, Molecular, and Optical Physics, 1009–21. New York, NY: Springer New York, 2006. http://dx.doi.org/10.1007/978-0-387-26308-3_69.

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Stenholm, Stig. "Absortion and Gain Spectra". En Springer Handbook of Atomic, Molecular, and Optical Physics, 1057–68. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-030-73893-8_73.

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Abernathy, C. R. "Growth of Group III Nitrides from Molecular Beams". En GaN and Related Materials, 11–51. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211082-2.

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Lavery, Danielle L. y Stefan Hoppler. "Gain-of-Function and Loss-of-Function Strategies in Xenopus". En Methods in Molecular Biology, 401–15. Totowa, NJ: Humana Press, 2008. http://dx.doi.org/10.1007/978-1-60327-469-25.

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Lipsitch, Marc. "Why Do Exceptionally Dangerous Gain-of-Function Experiments in Influenza?" En Methods in Molecular Biology, 589–608. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-8678-1_29.

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Marco, Francisco y Pedro Carrasco. "Transcriptome Analysis of PA Gain and Loss of Function Mutants". En Methods in Molecular Biology, 347–71. New York, NY: Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-7398-9_30.

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Apollonov, V. V. "Small-Signal Gain of CO2 Lasers Pumped by an SSVD". En High-Energy Molecular Lasers, 91–95. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-33359-5_15.

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Bjørklund, Martin Mæng, Juan A. Bernal y Jacob F. Bentzon. "Atherosclerosis Induced by Adeno-Associated Virus Encoding Gain-of-Function PCSK9". En Methods in Molecular Biology, 461–73. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1924-7_27.

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Actas de conferencias sobre el tema "Gain molecules"

Barnes, M. D., W. B. Whitten, J. M. Ramsey y S. Arnold. "Photophysics of Surfactant Molecules in Microdroplets". En Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/lacea.1996.lwb.6.

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Over the last several years, the study of fluorescence properties in both time and frequency domain of atoms in micron-sized optical cavities has held considerable interest in the physics and quantum optics communities. In addition to fascinating purely scientific aspects of the phenomenon of cavity quantum electrodynamics (QED), the ability to modify molecular fluorescence properties in a microcavity offers potentially significant sensitivity advantages for ultrasensitive - or, single molecule - fluorescence detection. For example, two important quantities which limit sensitivity in single molecule fluorescence detection - the saturated absorption rate and the integrated fluorescence yield - can be significantly increased by enhancing the fluorescence decay rate. We have shown previously that fluorescence decay rates1 as well as the integrated fluorescence yield2 of rhodamine 6G can be significantly enhanced in glycerol microdroplets. However, exploitation of these effects in order to gain sensitivity in single molecule fluorescence detection is nontrivial for at least two important reasons. First, the magnitude of decay rate enhancement depends on the position of the molecule within the droplet; molecules near the center of the droplet are not coupled to high Q resonances while molecules near the surface may strongly interact with cavity resonances associated with droplet. Thus, diffusion limits the amount of time a given molecule may interact with the resonances thereby limiting the fluorescence decay rate. Second, the fluorescence decay rate depends on the orientation of the transition moment with respect to the cavity "axis"; e.g., the surface normal for spherical cavities.

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Peng, Peng, Yonghao Mi, Marianna Lytova, Mathew Britton, Xiaoyan Ding, A. Yu Naumov, P. B. Corkum y D. M. Villeneuve. "Coherent control of molecular absorption line shape and optical gain in XUV". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.th2a.2.

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We demonstrated coherent control of molecular absorption line shape and optical gain in XUV. The control is achieved by creating a quantum coherence in the ground electronic state of hydrogen molecules.

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Truesdell, Keith A. y Richard A. Keller. "Intracavity gain detection: example I2, Br2". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.fa5.

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It is well known that a broadband dye laser is extremely sensitive to small absorption losses within the laser cavity and this phenomenon forms the basis for intracavity absorption spectroscopy. In a similar fashion, introduction of small optical gains into the laser cavity results in the laser locking onto wavelengths corresponding to these small gains. This internal gain injection locking leads to a method for (1) sensitive detection of small optical gains, and (2) specific state preparation for spectroscopic or chemical dynamic studies. A particularly attractive feature of this technique is that it is not necessary to know the wavelength where gain occurs before the measurement because the dye laser automatically finds the correct wavelength. Optical pumping with radiation from an external Ar+ laser was used to create population inversions between vibronic levels in molecular I2 and Br2 samples placed inside the cavity of a cw dye laser. We are able to detect optical gains as small as 2 × 10−5 on transitions between states in these molecules. By tuning the Lyot filter we are able to selectively populate specific, high-lying vibrational levels of the ground electronic state of both I2 and Br2. The internal injection resulted in the first reported cw lasing of Br2 in the visible spectral region.

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Grubbs, W. Tandy y Richard A. MacPhail. "High Resolution Stimulated Brillouin Gain Spectroscopy". En High Resolution Spectroscopy. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/hrs.1993.ma3.

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Brillouin spectroscopy has been an important source of information about the collective dynamics of molecules in liquids.1,2 In a conventional Brillouin experiment, a Fabry-Perot interferometer is used to measure the spectrum of laser light scattered at an angle θ by spontaneous density fluctuations in a sample. The Brillouin peaks in the spectrum arise from the acoustic wave component of these density fluctuations, and accordingly the shift of the Brillouin peaks from the elastic Rayleigh scattering peak corresponds to the acoustic frequency, while the width of the Brillouin peaks corresponds to the acoustic damping rate. By varying θ, and thus the scattering wavevector, one can determine the dispersion in the speed of sound and the acoustic attenuation, which in turn characterize the elastic and viscous responses of the fluid. A more detailed analysis of the spectral lineshape with the aid of generalized hydrodynamic theories allows one to determine the values of transport coefficients that describe the molecular dynamics.1

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Kodama, Yutaka y Heihachi Sato. "Effect of Molecular Sieve on Transient Output-Reduction and Laser Parameters in DC Discharged /Room Temperature Operated FAF CO Laser". En The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cthj5.

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The output power tends to transiently decrease with discharge time in a dc electrically pumped fast axial-flow (FAF) CO laser. This output reduction is mainly caused by both the temperature rise of gas mixture and deactivation of the excited CO molecule due to its dissociation into CO2 and O2 molecules.1 Especially, the latter seems to be predominant in the room temperature operated FAF CO laser system. The gas temperature rise due to the discharge can be compensated by fast gas-circulation through a heat exchanger along with either ethanol/dry ice coolants (or liquid nitrogen at subroom temperature operation) , whereas the CO2 molecules generated through the discharge process cannot be avoided at room temperature operation, though, it is well trapped with a cold trap of liquid nitrogen. Thus, we shall try to recover the output reduction transiently induced above by adsorbing the generated CO2 molecules by molecular sieve for the room temperature operation together with theoretical explanation. In addition, we shall also examine how the laser parameters such as the small-signal gain γ0.v saturation intensity Is and a measure of partial homogeneity m are influenced with insertion of molecular sieve.

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Kabanemi, Kalonji K., Jean-Franc¸ois He´tu y Samira H. Sammoun. "Experimental Study on Flow-Front Fingering Instabilities in Injection Molding of Polymer Solutions and Melts". En ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59078.

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An experimental investigation of the flow behavior of dilute, semi-dilute and concentrated polymer solutions has been carried out to gain a better understanding of the underlying mechanisms leading to the occurrence of instabilities at the advancing flow front during the filling of a mold cavity. Experiments were performed using various mass concentrations of low and high molecular weight polyacrylamide polymers in corn syrup and water. This paper reports a new type of elastic fingering instabilities at the advancing flow front that has been observed only in semi-dilute polymer solutions of high molecular weight polymers. These flow front elastic instabilities seem to arise as a result of a mixture of widely separated high molecular weight polymer molecules and low molecular weight solvent molecules, which gives rise to a largely non-uniform polydisperse solution, with respect to all the kinds of molecules in the resulting mixture (solvent molecules and polymer molecules). The occurrence of these instabilities appears to be independent of the injection flow rate and the cavity thickness. Moreover, these instabilities do not manifest themselves in dilute or concentrated regimes, where respectively, polymer molecules and solvent molecules are minor perturbation of the resulting solution. In those regimes, smooth flow fronts are confirmed from our experiments. Based on these findings, the experimental investigations have been extended to polymer melts. Different mixtures of polycarbonate melts of widely separated molecular weights (low and high molecular weights) were first prepared. The effect of the large polydispersity of the resulting mixtures on the flow front behavior was subsequently studied. The same instabilities at the flow front were observed only in the experiments where a very small amount of high molecular weight polycarbonate polymer has been mixed to a low molecular weight polycarbonate melt (oligomers).

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Kobayashi, Takayoshi. "Gain, Lasing, And Nonlinear Optical Properties Of Giant Dipole Molecules And Polydiacetylene". En 30th Annual Technical Symposium, editado por Garo Khanarian. SPIE, 1987. http://dx.doi.org/10.1117/12.939631.

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Yang, C. C. "Statistics of laser intensity amplified by a slightly saturated optical amplifier with a random gain medium". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.md1.

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Recently, attention has been paid to the laser noise caused by the turbulence in the gain cell of a gas or liquid laser. In such a gain medium, the spatial and/or temporal variations of resonance molecules are supposed to be stochastic. Therefore, the gain coefficient and propagation constant in this medium become random. In this research, the statistics of a linearly polarized monochromatic plane wave are evaluated after the wave is propagated through an optical amplifier with a random gain medium. A partially homogeneously broadened slightly saturated laser amplifier is considered. To deal with nonlinear propagation, the perturbation method is used in which the slight saturation is regarded as the perturbative factor. As for the random molecule distributions, the relative fluctuation of molecule number density is assumed to follow a Gaussian probability distribution. Also, a Gaussian correlation function is used for describing the random structure. The average laser intensity and the contrast of intensity fluctuation are to be evaluated. The couplings among the random gain, random propagation constant, and nonlinear effect are discussed. Here only weak turbulences are considered. Numerical examples are presented.

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Zaviyalov, Alexandr, Philippe Grelu y Falk Lederer. "Effect of Slow Gain Dynamics in Mode-Locked Fiber Lasers: Chirped Soliton Molecules". En Nonlinear Photonics. Washington, D.C.: OSA, 2012. http://dx.doi.org/10.1364/np.2012.nm4c.3.

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Coombe, Robert D. "Azide reactions for advanced chemical lasers". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.wh1.

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An efficient short-wavelength chemical laser will be a device which couples a highly constrained chemical pumping mechanism with an atomic or molecular species whose spectroscopic characteristics are appropriate for lasing. Research in the past several years has identified a number of candidates (e.g., interhalogens, group VI atoms and molecules, CN, NO, and others) which are capable of lasing in the UV or visible regions. Recent work in our laboratory has sought means by which the very highly constrained reactions of azide radicals may be used to pump these known candidate systems. The electronic ground state of N3 correlates adiabatically to an excited N(2D) atom and a ground state N2 molecule. As a consequence, R + N3 reactions effectively proceed on excited state potential energy surfaces and are very strongly constrained to produce electronically excited metastable NR molecules. This view is supported by experimental studies of reactions of N3 with a number of first and second row atoms.1,2 The products of these reactions are useful as either energy storage agents or lasing species in a number of potential SWCL systems. N3 reactions can be operated in either continuous or pulsed modes. Pulsed experiments with these systems hold promise for early tests at reagent densities commensurate with measurable gain levels.

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Informes sobre el tema "Gain molecules"

J.S. Bakos, G. Djotyan, Zsuzsa Soerlei, J. Szigeti, D. K. Mansfield y J. Sarkozi. Broadening and shifting of the methanol 119 {mu}m gain line of linear and circular polarization by collision with chiral molecules. Office of Scientific and Technical Information (OSTI), junio de 2000. http://dx.doi.org/10.2172/756995.

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Azim, Gamal-Abdel y A. E. Gene Freeman. Maximum Gain by Using Molecular Markers for Selection. Ames (Iowa): Iowa State University, enero de 2004. http://dx.doi.org/10.31274/ans_air-180814-34.

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McClure, Michael A., Yitzhak Spiegel, David M. Bird, R. Salomon y R. H. C. Curtis. Functional Analysis of Root-Knot Nematode Surface Coat Proteins to Develop Rational Targets for Plantibodies. United States Department of Agriculture, octubre de 2001. http://dx.doi.org/10.32747/2001.7575284.bard.

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The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.

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Schroyen, Martine, Juan Pedro Steibel, Igseo Choi, James E. Koltes, Christopher J. Eisley, Eric R. Fritz-Waters, James M. Reecy et al. Identifying Molecular Differences in Pigs with Extreme Phenotypes for Weight Gain and Viral Load in Response to PRRS. Ames (Iowa): Iowa State University, enero de 2015. http://dx.doi.org/10.31274/ans_air-180814-1332.

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Hodges, Thomas K. y David Gidoni. Regulated Expression of Yeast FLP Recombinase in Plant Cells. United States Department of Agriculture, septiembre de 2000. http://dx.doi.org/10.32747/2000.7574341.bard.

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Research activities in both our laboratories were directed toward development of control of the FLP/frt recombination system for plants. As described in the text of the research proposal, the US lab has been engaged in developing regulatory strategies such as tissue-specific promoters and the steroid-inducible activation of the FLP enzyme while the main research activities in Israel have been directed toward the development and testing of a copper-regulated expression of flp recombinase in tobacco (this is an example of a promoter activation by metal ions). The Israeli lab hat additionally completed experiments of previous studies regarding factors affecting the efficiency of recombinase activity using both a gain-of-function assay (excisional-activation of a gusA marker) and loss of function assay (excision of a rolC marker) in tobacco. Site-specific recombinase systems, in particular the FLP/frt and R/RS systems of yeast and the Cre/lox system of bacteriophage P1, have become an essential component of targeted genetic transformation procedures both in animal and plant organisms. To provide more flexibility in transgene excisions by the recombinase systems as well as gene targeting, and to widen possible applications, the development of controlled or regulated recombination systems is highly desirable and was therefore the subject of this research proposal. There are a few possible mechanisms to regulate expression of a recombinase system. They include: 1) control of the recombination system by having the target sites (e.g. frt) in one plant and the flp recombinase gene in another, and bringing the two together by cross fertilization. 2) regulation of promoter activities by external stimuli such as temperature, chemicals, metal ions, etc. 3) regulation of promoter activities by internal signals, i.e. cell- or tissue-specific, or developmental regulation. 4) regulation of enzyme activity by providing cofactors essential for biochemical reactions to take place such as steroid molecules in conjunction with a steroid ligand-binding protein (domains). During the course of this research our major emphasis have been focused toward studying the feasibility of hybrid seed production in Arabidopsis, using FLP/frt. Male-sterility was induced using the antisence of a pollen- and tapetum-specific gene, bcp1, isolated from Arabidopsis. The sterility inducing gene was flanked by frt sites. Upon cross pollination of flowers of male-sterile plants with pollen from FLP-containing plants, viable seeds were produced, and the progeny hybrid plants developed normally. The major achievement from this work is the first demonstration of using a site-specific recombinase to restore fertility in male-sterile plants (see attached paper, Luo et al., Plant J 2000; 23:423-430). The implication from this finding is that site-specific recombination systems can be applied in crop plants as a useful alternative method for hybrid seed production.

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Speck, James S. Systematic Studies of Carbon Doping in High Quality GaN Grown by Molecular Beam Epitaxy. Fort Belvoir, VA: Defense Technical Information Center, diciembre de 2004. http://dx.doi.org/10.21236/ada430009.

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Morin, Shai, Gregory Walker, Linda Walling y Asaph Aharoni. Identifying Arabidopsis thaliana Defense Genes to Phloem-feeding Insects. United States Department of Agriculture, febrero de 2013. http://dx.doi.org/10.32747/2013.7699836.bard.

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The whitefly (Bemisia tabaci) is a serious agricultural pest that afflicts a wide variety of ornamental and vegetable crop species. To enable survival on a great diversity of host plants, whiteflies must have the ability to avoid or detoxify numerous different plant defensive chemicals. Such toxins include a group of insect-deterrent molecules called glucosinolates (GSs), which also provide the pungent taste of Brassica vegetables such as radish and cabbage. In our BARD grant, we used the whitefly B. tabaci and Arabidopsis (a Brassica plant model) defense mutants and transgenic lines, to gain comprehensive understanding both on plant defense pathways against whiteflies and whitefly defense strategies against plants. Our major focus was on GSs. We produced transgenic Arabidopsis plants accumulating high levels of GSs. At the first step, we examined how exposure to high levels of GSs affects decision making and performance of whiteflies when provided plants with normal levels or high levels of GSs. Our major conclusions can be divided into three: (I) exposure to plants accumulating high levels of GSs, negatively affected the performance of both whitefly adult females and immature; (II) whitefly adult females are likely to be capable of sensing different levels of GSs in their host plants and are able to choose, for oviposition, the host plant on which their offspring survive and develop better (preference-performance relationship); (III) the dual presence of plants with normal levels and high levels of GSs, confused whitefly adult females, and led to difficulties in making a choice between the different host plants. These findings have an applicative perspective. Whiteflies are known as a serious pest of Brassica cropping systems. If the differences found here on adjacent small plants translate to field situations, intercropping with closely-related Brassica cultivars could negatively influence whitefly population build-up. At the second step, we characterized the defensive mechanisms whiteflies use to detoxify GSs and other plant toxins. We identified five detoxification genes, which can be considered as putative "key" general induced detoxifiers because their expression-levels responded to several unrelated plant toxic compounds. This knowledge is currently used (using new funding) to develop a new technology that will allow the production of pestresistant crops capable of protecting themselves from whiteflies by silencing insect detoxification genes without which successful host utilization can not occur. Finally, we made an effort to identify defense genes that deter whitefly performance, by infesting with whiteflies, wild-type and defense mutated Arabidopsis plants. The infested plants were used to construct deep-sequencing expression libraries. The 30- 50 million sequence reads per library, provide an unbiased and quantitative assessment of gene expression and contain sequences from both Arabidopsis and whiteflies. Therefore, the libraries give us sequence data that can be mined for both the plant and insect gene expression responses. An intensive analysis of these datasets is underway. We also conducted electrical penetration graph (EPG) recordings of whiteflies feeding on Arabidopsis wild-type and defense mutant plants in order to determine the time-point and feeding behavior in which plant-defense genes are expressed. We are in the process of analyzing the recordings and calculating 125 feeding behavior parameters for each whitefly. From the analyses conducted so far we conclude that the Arabidopsis defense mutants do not affect adult feeding behavior in the same manner that they affect immatures development. Analysis of the immatures feeding behavior is not yet completed, but if it shows the same disconnect between feeding behavior data and developmental rate data, we would conclude that the differences in the defense mutants are due to a qualitative effect based on the chemical constituency of the phloem sap.

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Meir, Shimon, Michael S. Reid, Cai-Zhong Jiang, Amnon Lers y Sonia Philosoph-Hadas. Molecular Studies of Postharvest Leaf and Flower Senescence. United States Department of Agriculture, enero de 2011. http://dx.doi.org/10.32747/2011.7592657.bard.

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Original objectives: To understand the regulation of abscission by exploring the nature of changes of auxin-related gene expression in tomato (Lycopersicon esculatumMill) abscission zones (AZs) following organ removal, and by analyzing the function of these genes. Our specific goals were: 1) To complete the microarray analyses in tomato flower and leaf AZs, for identifying genes whose expression changes early in response to auxin depletion; 2) To examine, using virus-induced gene silencing (VIGS), the effect of silencing target genes on ethylene sensitivity and abscission competence of the leaf and flower AZs; 3) To isolate and characterize promoters from AZ-specific genes to be used in functional analysis; 4) To generate stable transgenic tomato plants with selected genes silenced with RNAi, under the control of an AZ-specific promoter, for further characterization of their abscission phenotypes. Background: Abscission, the separation of organs from the parent plant, results in postharvest quality loss in many ornamentals and other fresh produce. The process is initiated by changes in the auxin gradient across the AZ, and is triggered by ethylene. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the initiation of the abscission process, as the AZ becomes sensitized to ethylene. The present project was focused on elucidating these early molecular regulatory events, in order to gain a better control of the abscission process for agricultural manipulations. Major conclusions, solutions, achievements: Microarray analyses, using the Affymetrix Tomato GeneChip®, revealed changes in expression, occurring early in abscission, of many genes with possible regulatory functions. These included a range of auxin- and ethylene-related transcription factors (TFs), other TFs that are transiently induced just after flower removal, and a set of novel AZ-specific genes. We also identified four different defense-related genes, including: Cysteine-type endopeptidase, α- DOX1, WIN2, and SDF2, that are newly-associated with the late stage of the abscission process. This supports the activation of different defense responses and strategies at the late abscission stages, which may enable efficient protection of the exposed tissue toward different environmental stresses. To facilitate functional studies we implemented an efficient VIGS system in tomato, and isolated two abscission-specific promoters (pTAPG1 and pTAPG4) for gene silencing in stable transformation. Using the VIGS system we could demonstrate the importance of TAPGs in abscission of tomato leaf petioles, and evaluated the importance of more than 45 genes in abscission. Among them we identified few critical genes involved in leaf and flower abscission. These included: PTRP-F1, PRP, TKN4, KNOTTED-like homeobox TF, KD1, and KNOX-like homeodomain protein genes, the silencing of which caused a striking retardation of pedicel abscission, and ERF1, ERF4, Clavata-like3 protein, Sucrose transporter protein, and IAA10 genes, the silencing of which delayed petiole abscission. The importance of PRPand KD1 genes in abscission was confirmed also by antisense–silencing using pTAPG4. Experiments testing the effects of RNAi silencing of few other genes are still in progress, The analysis of the microarray results of flower and leaf AZs allowed us to establish a clear sequence of events occurring during acquisition of tissue sensitivity to ethylene, and to confirm our hypothesis that acquisition of ethylene sensitivity in the AZ is associated with altered expression of auxin-regulated genes in both AZs. Implication, both scientific and agricultural: Our studies had provided new insights into the regulation of the abscission process, and shaded light on the molecular mechanisms that drive the acquisition of abscission competence in the AZ. We pointed out some critical genes involved in regulation of abscission, and further expanded our knowledge of auxin-ethylene cross talk during the abscission process. This permits the development of novel techniques for manipulating abscission, and thereby improving the postharvest performance of ornamentals and other crops.

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Lever, James y Jason Weale. High efficiency fuel sleds for Polar traverses. Engineer Research and Development Center (U.S.), marzo de 2022. http://dx.doi.org/10.21079/11681/43445.

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We describe here the evolution of lightweight, high-efficiency fuel sleds for Polar over-snow traverses. These sleds consist of flexible bladders strapped to sheets of high molecular weight polyethylene. They cost 1/6th, weigh 1/10th and triple the fuel delivered per towing tractor compared with steel sleds. An eight-tractor fleet has conducted three 3400-km roundtrips to South Pole with each travers delivering 320,000 kg of fuel while emitting <1% the pollutants, consuming 1/2 the fuel and saving $1.6 M compared with aircraft resupply. A two tractor fleet in Greenland recently delivered 83,000 kg of fuel in bladder sleds to Summit with similar benefits. Performance monitoring has revealed that bladder-sled towing resistance is largely governed by sliding friction, which can start high and drop in half over the first 30 min of travel. Frictional heating probably produces a thin water layer that lubricates the sled–snow interface. Consequently, towing resistance depends on the thermal budget of the sled. For example, black fuel bladders increase solar gain and thus decrease sled resistance; data suggest they could double again the fuel delivered per tractor. The outstanding efficiency and low cost of these sleds has transformed fuel delivery to Polar research stations.

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Paran, Ilan y Molly Jahn. Genetics and comparative molecular mapping of biochemical and morphological fruit characters in Capsicum. United States Department of Agriculture, marzo de 2005. http://dx.doi.org/10.32747/2005.7586545.bard.

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Original objectives: The overall goal of our work was to gain information regarding the genetic and molecular control of pathways leading to the production of secondary metabolites determining major fruit quality traits in pepper and to develop tools based on this information to assist in crop improvement. The specific objectives were to: (1) Generate a molecular map of pepper based on simple sequence repeat (SSR) markers. (2) Map QTL for capsaicinoid (pungency) content (3) Determine possible association between capsaicinoid and carotenoid content and structural genes for capsaicinoid and carotenoid biosynthesis. (4) Map QTL for quantitative traits controlling additional fruit traits. (5) Map fruit-specific ESTs and determine possible association with fruit QTL (6) Map the C locus that determines the presence and absence of capsaicinoid in pepper fruit and identify candidate genes for C.locus. Background: Pungency, color, fruit shape and fruit size are among the most important fruit quality characteristics of pepper. Despite the importance of the pepper crop both in the USA and Israel, the genetic basis of these traits was poorly understood prior to the studies conducted in the present proposal. In addition, molecular tools for use in pepper improvement were lacking. Major conclusions and achievements: Our studies enabled the development of a saturated genetic map of pepper that includes numerous SSR markers. This map has been integrated with a number of other independent maps resulting in the publication of a single resource map consisting of more than 2000 markers. Unlike previous maps based primarily on tomato-originated RFLP markers, the new maps are based on PCR markers that originate in Capsicum providing a comprehensive and versatile resource for marker-assisted selection in pepper. We determined the genetic and molecular bases of qualitative and quantitative variation of pungency, a character unique to pepper fruit. We mapped and subsequently cloned the Pun1 gene that serves as a master regulatoar for capsaicinoid accumulation and showed that it is an acyltransferase. By sequencing the Pun1 gene in pungent and non-pungent cultivars we identified a deletion that abolishes the expression of the gene in the latter cultivars. We also identified QTL that control capsaicinoid content and therefore pungency level. These genes will allow pepper breeders to manipulate the level of pungency for specific agricultural and industrial purposes. In addition to pungency we identified genes and QTL that control other key developmental processes of fruit development such as color, texture and fruit shape. The A gene controlling anthocyanin accumulation in the immature fruit was found as the ortholog of the petunia transcription factor Anthocyanin2. The S gene required for the soft flesh and deciduous fruit nature typical of wild peppers was identified as the ortholog of tomato polygalacturonase. We identified two major QTL controlling fruit shape, fs3.1 and fs10.1, that differentiate elongated and blocky and round fruit shapes, respectively. Scientific and agricultural implications: Our studies allowed significant advances in our understanding of important processes of pepper fruit development including the isolation and characterization of several well known genes. These results also provided the basis for the development of molecular tools that can be implemented for pepper improvement. A total of eleven refereed publications have resulted from this work, and several more are in preparation.

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