WorldWideScience

Sample records for evolution generation regeneration

  1. A curriculum vitae of teeth: evolution, generation, regeneration.

    Science.gov (United States)

    Koussoulakou, Despina S; Margaritis, Lukas H; Koussoulakos, Stauros L

    2009-01-01

    The ancestor of recent vertebrate teeth was a tooth-like structure on the outer body surface of jawless fishes. Over the course of 500,000,000 years of evolution, many of those structures migrated into the mouth cavity. In addition, the total number of teeth per dentition generally decreased and teeth morphological complexity increased. Teeth form mainly on the jaws within the mouth cavity through mutual, delicate interactions between dental epithelium and oral ectomesenchyme. These interactions involve spatially restricted expression of several, teeth-related genes and the secretion of various transcription and signaling factors. Congenital disturbances in tooth formation, acquired dental diseases and odontogenic tumors affect millions of people and rank human oral pathology as the second most frequent clinical problem. On the basis of substantial experimental evidence and advances in bioengineering, many scientists strongly believe that a deep knowledge of the evolutionary relationships and the cellular and molecular mechanisms regulating the morphogenesis of a given tooth in its natural position, in vivo, will be useful in the near future to prevent and treat teeth pathologies and malformations and for in vitro and in vivo teeth tissue regeneration.

  2. Evolution and developmental diversity of tooth regeneration.

    Science.gov (United States)

    Tucker, Abigail S; Fraser, Gareth J

    2014-01-01

    This review considers the diversity observed during both the development and evolution of tooth replacement throughout the vertebrates in a phylogenetic framework from basal extant chondrichthyan fish and more derived teleost fish to mammals. We illustrate the conservation of the tooth regeneration process among vertebrate clades, where tooth regeneration refers to multiple tooth successors formed de novo for each tooth position in the jaws from a common set of retained dental progenitor cells. We discuss the conserved genetic mechanisms that might be modified to promote morphological diversity in replacement dentitions. We review current research and recent progress in this field during the last decade that have promoted our understanding of tooth diversity in an evolutionary developmental context, and show how tooth replacement and dental regeneration have impacted the evolution of the tooth-jaw module in vertebrates. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Development, regeneration, and evolution of feathers.

    Science.gov (United States)

    Chen, Chih-Feng; Foley, John; Tang, Pin-Chi; Li, Ang; Jiang, Ting Xin; Wu, Ping; Widelitz, Randall B; Chuong, Cheng Ming

    2015-01-01

    The feather is a complex ectodermal organ with hierarchical branching patterns. It provides functions in endothermy, communication, and flight. Studies of feather growth, cycling, and health are of fundamental importance to avian biology and poultry science. In addition, feathers are an excellent model for morphogenesis studies because of their accessibility, and their distinct patterns can be used to assay the roles of specific molecular pathways. Here we review the progress in aspects of development, regeneration, and evolution during the past three decades. We cover the development of feather buds in chicken embryos, regenerative cycling of feather follicle stem cells, formation of barb branching patterns, emergence of intrafeather pigmentation patterns, interplay of hormones and feather growth, and the genetic identification of several feather variants. The discovery of feathered dinosaurs redefines the relationship between feathers and birds. Inspiration from biomaterials and flight research further fuels biomimetic potential of feathers as a multidisciplinary research focal point.

  4. Next generation PON evolution

    Science.gov (United States)

    Srivastava, Anand

    2013-01-01

    Passive optical network (PON) features a point-to-multi-point (P2MP) architecture to provide broadband access. The P2MP architecture has become the most popular solution for FTTx deployment among operators. PON-based FTTx has been widely deployed ever since 2004 when ITU-T Study Group 15Q2 completed recommendations that defined GPON system [ITU-T seriesG.984]. As full services are provisioned by the massive deployment of PON networks worldwide, operators expect more from PONs. These include improved bandwidths and service support capabilities as well as enhanced performance of access nodes and supportive equipment over their existing PON networks. The direction of PON evolution is a key issue for the telecom industry. Full Service Access Network (FSAN) and ITU-T are the PON interest group and standard organization, respectively. In their view, the next-generation PONs are divided into two phases: NG-PON1 and NG-PON2. Mid-term upgrades in PON networks are defined as NG-PON1, while NG-PON2 is a long-term solution in PON evolution. Major requirements of NG-PON1 are the coexistence with the deployed GPON systems and the reuse of outside plant. Optical Distribution Networks (ODNs) account for 70% of the total investments in deploying PONs. Therefore, it is crucial for the NGPON evolution to be compatible with the deployed networks. With the specification of system coexistence and ODN reuse, the only hold-up of the migration from GPON to NG-PON1 is the maturity of the industry chain. Unlike NG-PON1 that has clear goals and emerging developments, there are many candidate technologies for NG-PON2. The selection of NG-PON2 is under discussion. However, one thing is clear, NG-PON2 technology must outperform NG-PON1 technologies in terms of ODN compatibility, bandwidth, capacity, and cost-efficiency.

  5. Concept Generation in Language Evolution

    OpenAIRE

    Lewis, Martha; Lawry, Jonathan

    2016-01-01

    This thesis investigates the generation of new concepts from combinations of existing concepts as a language evolves. We give a method for combining concepts, and will be investigating the utility of composite concepts in language evolution and thence the utility of concept generation.

  6. Amplification and Re-Generation of LNA-Modified Libraries

    DEFF Research Database (Denmark)

    Doessing, Holger; Hansen, Lykke H.; Veedu, Rakesh N.

    2012-01-01

    Locked nucleic acids (LNA) confer high thermal stability and nuclease resistance to oligonucleotides. The discovery of polymerases that accept LNA triphosphates has led us to propose a scheme for the amplification and re-generation of LNA-containing oligonucleotide libraries. Such libraries could...... be used for in vitro selection of e.g., native LNA aptamers. We maintained an oligonucleotide library encoding 40 randomized positions with LNA ATP, GTP, CTP, and TTP for 7 rounds of ‘mock’ in vitro selection in the absence of a target and analyzed the sequence composition after rounds 1, 4 and 7. We...... observed a decrease in LNA-A content from 20.5% in round 1 to 6.6% in round 7. This decrease was accompanied by a substantial bias against successive LNA-As (poly-LNA adenosine tracts) and a relative over-representation of single LNA-As. Maintaining a library with LNA TTP yielded similar results. Together...

  7. Generating private co-investments in area-based urban regeneration: Lessons from Denmark

    DEFF Research Database (Denmark)

    Jensen, Jesper Ole; Larsen, Jacob Norvig; Storgaard, Kresten

    a factor 5 times higher than the public investments in the areas, in terms of urban regeneration subsidies. Private investments, however, might cover different property investment strategies: ‘Passive management’, ‘active management’ and ‘development’. We suggest that for the urban regeneration areas......In recent years, public-private collaboration as well as private co-investments has been intensely promoted in Danish area-based urban regeneration policy and programmes. The paper will discuss to which extent these ambitions have been full-filled, and what has actually attracted private...... investments to the urban regeneration areas. The paper is based on evaluations of the Danish area-based regeneration programmes, as well as research on private investments in selected urban regeneration areas. Our research shows that area-based urban regeneration in average generates private investments...

  8. The sea cucumber genome provides insights into morphological evolution and visceral regeneration.

    Directory of Open Access Journals (Sweden)

    Xiaojun Zhang

    2017-10-01

    Full Text Available Apart from sharing common ancestry with chordates, sea cucumbers exhibit a unique morphology and exceptional regenerative capacity. Here we present the complete genome sequence of an economically important sea cucumber, A. japonicus, generated using Illumina and PacBio platforms, to achieve an assembly of approximately 805 Mb (contig N50 of 190 Kb and scaffold N50 of 486 Kb, with 30,350 protein-coding genes and high continuity. We used this resource to explore key genetic mechanisms behind the unique biological characters of sea cucumbers. Phylogenetic and comparative genomic analyses revealed the presence of marker genes associated with notochord and gill slits, suggesting that these chordate features were present in ancestral echinoderms. The unique shape and weak mineralization of the sea cucumber adult body were also preliminarily explained by the contraction of biomineralization genes. Genome, transcriptome, and proteome analyses of organ regrowth after induced evisceration provided insight into the molecular underpinnings of visceral regeneration, including a specific tandem-duplicated prostatic secretory protein of 94 amino acids (PSP94-like gene family and a significantly expanded fibrinogen-related protein (FREP gene family. This high-quality genome resource will provide a useful framework for future research into biological processes and evolution in deuterostomes, including remarkable regenerative abilities that could have medical applications. Moreover, the multiomics data will be of prime value for commercial sea cucumber breeding programs.

  9. The sea cucumber genome provides insights into morphological evolution and visceral regeneration.

    Science.gov (United States)

    Zhang, Xiaojun; Sun, Lina; Yuan, Jianbo; Sun, Yamin; Gao, Yi; Zhang, Libin; Li, Shihao; Dai, Hui; Hamel, Jean-François; Liu, Chengzhang; Yu, Yang; Liu, Shilin; Lin, Wenchao; Guo, Kaimin; Jin, Songjun; Xu, Peng; Storey, Kenneth B; Huan, Pin; Zhang, Tao; Zhou, Yi; Zhang, Jiquan; Lin, Chenggang; Li, Xiaoni; Xing, Lili; Huo, Da; Sun, Mingzhe; Wang, Lei; Mercier, Annie; Li, Fuhua; Yang, Hongsheng; Xiang, Jianhai

    2017-10-01

    Apart from sharing common ancestry with chordates, sea cucumbers exhibit a unique morphology and exceptional regenerative capacity. Here we present the complete genome sequence of an economically important sea cucumber, A. japonicus, generated using Illumina and PacBio platforms, to achieve an assembly of approximately 805 Mb (contig N50 of 190 Kb and scaffold N50 of 486 Kb), with 30,350 protein-coding genes and high continuity. We used this resource to explore key genetic mechanisms behind the unique biological characters of sea cucumbers. Phylogenetic and comparative genomic analyses revealed the presence of marker genes associated with notochord and gill slits, suggesting that these chordate features were present in ancestral echinoderms. The unique shape and weak mineralization of the sea cucumber adult body were also preliminarily explained by the contraction of biomineralization genes. Genome, transcriptome, and proteome analyses of organ regrowth after induced evisceration provided insight into the molecular underpinnings of visceral regeneration, including a specific tandem-duplicated prostatic secretory protein of 94 amino acids (PSP94)-like gene family and a significantly expanded fibrinogen-related protein (FREP) gene family. This high-quality genome resource will provide a useful framework for future research into biological processes and evolution in deuterostomes, including remarkable regenerative abilities that could have medical applications. Moreover, the multiomics data will be of prime value for commercial sea cucumber breeding programs.

  10. Temporal evolution of mechanical properties of skeletal tissue regeneration in rabbits. An experimental study

    CERN Document Server

    Mokoko, Didier; Chabrand, Patrick

    2007-01-01

    Various mathematical models represent the effects of local mechanical environment on the regulation of skeletal regeneration. Their relevance relies on an accurate description of the evolving mechanical properties of the regenerating tissue. The object of this study was to develop an experimental model which made it possible to characterize the temporal evolution of the structural and mechanical properties during unloaded enchondral osteogenesis in the New Zealand rabbit, a standard animal model for studies of osteogenesis and chondrogenesis. A 25mm segment of tibial diaphysis was removed sub-periosteally from rabbits. The defect was repaired by the preserved periosteum. An external fixator was applied to prevent mechanical loading during osteogenesis. The regenerated skeletal tissues were studied by CT scan, histology and mechanical tests. The traction tests between 7 to 21 days post-surgery were done on formaldehyde-fixated tissue allowing to obtain force/displacement curves. The viscoelastic properties of ...

  11. Generation and evolution of interplanetary slow shocks

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    1996-04-01

    Full Text Available It is well known that most MHD shocks observed within 1 AU are MHD fast shocks. Only a very limited number of MHD slow shocks are observed within 1 AU. In order to understand why there are only a few MHD slow shocks observed within 1 AU, we use a one-dimensional, time-dependent MHD code with an adaptive grid to study the generation and evolution of interplanetary slow shocks (ISS in the solar wind. Results show that a negative, nearly square-wave perturbation will generate a pair of slow shocks (a forward and a reverse slow shock. In addition, the forward and the reverse slow shocks can pass through each other without destroying their characteristics, but the propagating speeds for both shocks are decreased. A positive, square-wave perturbation will generate both slow and fast shocks. When a forward slow shock (FSS propagates behind a forward fast shock (FFS, the former experiences a decreasing Mach number. In addition, the FSS always disappears within a distance of 150R⊙ (where R⊙ is one solar radius from the Sun when there is a forward fast shock (with Mach number ≥1.7 propagating in front of the FSS. In all tests that we have performed, we have not discovered that the FSS (or reverse slow shock evolves into a FFS (or reverse fast shock. Thus, we do not confirm the FSS-FFS evolution as suggested by Whang (1987.

  12. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration.

    Science.gov (United States)

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-02-08

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40(phox) and p47(phox)) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration.

  13. Generation and evolution of interplanetary slow shocks

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    Full Text Available It is well known that most MHD shocks observed within 1 AU are MHD fast shocks. Only a very limited number of MHD slow shocks are observed within 1 AU. In order to understand why there are only a few MHD slow shocks observed within 1 AU, we use a one-dimensional, time-dependent MHD code with an adaptive grid to study the generation and evolution of interplanetary slow shocks (ISS in the solar wind. Results show that a negative, nearly square-wave perturbation will generate a pair of slow shocks (a forward and a reverse slow shock. In addition, the forward and the reverse slow shocks can pass through each other without destroying their characteristics, but the propagating speeds for both shocks are decreased. A positive, square-wave perturbation will generate both slow and fast shocks. When a forward slow shock (FSS propagates behind a forward fast shock (FFS, the former experiences a decreasing Mach number. In addition, the FSS always disappears within a distance of 150R (where R is one solar radius from the Sun when there is a forward fast shock (with Mach number ≥1.7 propagating in front of the FSS. In all tests that we have performed, we have not discovered that the FSS (or reverse slow shock evolves into a FFS (or reverse fast shock. Thus, we do not confirm the FSS-FFS evolution as suggested by Whang (1987.

  14. Semi-automated ontology generation and evolution

    Science.gov (United States)

    Stirtzinger, Anthony P.; Anken, Craig S.

    2009-05-01

    Extending the notion of data models or object models, ontology can provide rich semantic definition not only to the meta-data but also to the instance data of domain knowledge, making these semantic definitions available in machine readable form. However, the generation of an effective ontology is a difficult task involving considerable labor and skill. This paper discusses an Ontology Generation and Evolution Processor (OGEP) aimed at automating this process, only requesting user input when un-resolvable ambiguous situations occur. OGEP directly attacks the main barrier which prevents automated (or self learning) ontology generation: the ability to understand the meaning of artifacts and the relationships the artifacts have to the domain space. OGEP leverages existing lexical to ontological mappings in the form of WordNet, and Suggested Upper Merged Ontology (SUMO) integrated with a semantic pattern-based structure referred to as the Semantic Grounding Mechanism (SGM) and implemented as a Corpus Reasoner. The OGEP processing is initiated by a Corpus Parser performing a lexical analysis of the corpus, reading in a document (or corpus) and preparing it for processing by annotating words and phrases. After the Corpus Parser is done, the Corpus Reasoner uses the parts of speech output to determine the semantic meaning of a word or phrase. The Corpus Reasoner is the crux of the OGEP system, analyzing, extrapolating, and evolving data from free text into cohesive semantic relationships. The Semantic Grounding Mechanism provides a basis for identifying and mapping semantic relationships. By blending together the WordNet lexicon and SUMO ontological layout, the SGM is given breadth and depth in its ability to extrapolate semantic relationships between domain entities. The combination of all these components results in an innovative approach to user assisted semantic-based ontology generation. This paper will describe the OGEP technology in the context of the architectural

  15. Entropy generation in a parallel-plate active magnetic regenerator with insulator layers

    Science.gov (United States)

    Mugica Guerrero, Ibai; Poncet, Sébastien; Bouchard, Jonathan

    2017-02-01

    This paper proposes a feasible solution to diminish conduction losses in active magnetic regenerators. Higher performances of these machines are linked to a lower thermal conductivity of the Magneto-Caloric Material (MCM) in the streamwise direction. The concept presented here involves the insertion of insulator layers along the length of a parallel-plate magnetic regenerator in order to reduce the heat conduction within the MCM. This idea is investigated by means of a 1D numerical model. This model solves not only the energy equations for the fluid and solid domains but also the magnetic circuit that conforms the experimental setup of reference. In conclusion, the addition of insulator layers within the MCM increases the temperature span, cooling load, and coefficient of performance by a combination of lower heat conduction losses and an increment of the global Magneto-Caloric Effect. The generated entropy by solid conduction, fluid convection, and conduction and viscous losses are calculated to help understand the implications of introducing insulator layers in magnetic regenerators. Finally, the optimal number of insulator layers is studied.

  16. Hydroxyl-dependent Evolution of Oxygen Vacancies Enables the Regeneration of BiOCl photocatalyst

    KAUST Repository

    Wu, Sujuan

    2017-05-02

    Photoinduced oxygen vacancies (OVs) are widely investigated as a vital point defect in wide-band-gap semiconductors. Still, the formation mechanism of OVs remains unclear in various materials. To elucidate the formation mechanism of photoinduced OVs in bismuth oxychloride (BiOCl), we synthesized two surface hydroxyl discrete samples in light of the discovery of the significant variance of hydroxyl groups before and after UV light exposure. It is noted that OVs can be obtained easily after UV light irradiation in the sample with surface hydroxyl groups, while variable changes were observed in samples without surface hydroxyls. Density functional theory (DFT) calculations reveal that the binding energy of Bi-O is drastically influenced by surficial hydroxyl groups, which is intensely correlated to the formation of photoinduced OVs. Moreover, DFT calculations reveal that the adsorbed water molecules are energetically favored to dissociate into separate hydroxyl groups at the OV sites via proton transfer to a neighboring bridging oxygen atom, forming two bridging hydroxyl groups per initial oxygen vacancy. This result is consistent with the experimental observation that the disappearance of photoinduced OVs and the recovery of hydroxyl groups on the surface of BiOCl after exposed to a H2O(g)-rich atmosphere, and finally enables the regeneration of BiOCl photocatalyst. Here, we introduce new insights that the evolution of photoinduced OVs is dependent on surface hydroxyl groups, which will lead to the regeneration of active sites in semiconductors. This work is useful for controllable designs of defective semiconductors for applications in photocatalysis and photovoltaics.

  17. Generative NeuroEvolution for Deep Learning

    OpenAIRE

    Verbancsics, Phillip; Harguess, Josh

    2013-01-01

    An important goal for the machine learning (ML) community is to create approaches that can learn solutions with human-level capability. One domain where humans have held a significant advantage is visual processing. A significant approach to addressing this gap has been machine learning approaches that are inspired from the natural systems, such as artificial neural networks (ANNs), evolutionary computation (EC), and generative and developmental systems (GDS). Research into deep learning has ...

  18. Tooth regeneration: a revolution in stomatology and evolution in regenerative medicine.

    Science.gov (United States)

    Yildirim, Sibel; Fu, Susan Y; Kim, Keith; Zhou, Hong; Lee, Chang Hun; Li, Ang; Kim, Sahng Gyoon; Wang, Shuang; Mao, Jeremy J

    2011-07-01

    A tooth is a complex biological organ and consists of multiple tissues including the enamel, dentin, cementum and pulp. Tooth loss is the most common organ failure. Can a tooth be regenerated? Can adult stem cells be orchestrated to regenerate tooth structures such as the enamel, dentin, cementum and dental pulp, or even an entire tooth? If not, what are the therapeutically viable sources of stem cells for tooth regeneration? Do stem cells necessarily need to be taken out of the body, and manipulated ex vivo before they are transplanted for tooth regeneration? How can regenerated teeth be economically competitive with dental implants? Would it be possible to make regenerated teeth affordable by a large segment of the population worldwide? This review article explores existing and visionary approaches that address some of the above-mentioned questions. Tooth regeneration represents a revolution in stomatology as a shift in the paradigm from repair to regeneration: repair is by metal or artificial materials whereas regeneration is by biological restoration. Tooth regeneration is an extension of the concepts in the broad field of regenerative medicine to restore a tissue defect to its original form and function by biological substitutes.

  19. Hydrogen Generation in Microbial Reverse-Electrodialysis Electrolysis Cells Using a Heat-Regenerated Salt Solution

    KAUST Repository

    Nam, Joo-Youn

    2012-05-01

    Hydrogen gas can be electrochemically produced in microbial reverse-electrodialysis electrolysis cells (MRECs) using current derived from organic matter and salinity-gradient energy such as river water and seawater solutions. Here, it is shown that ammonium bicarbonate salts, which can be regenerated using low-temperature waste heat, can also produce sufficient voltage for hydrogen gas generation in an MREC. The maximum hydrogen production rate was 1.6 m3 H2/m3·d, with a hydrogen yield of 3.4 mol H2/mol acetate at a salinity ratio of infinite. Energy recovery was 10% based on total energy applied with an energy efficiency of 22% based on the consumed energy in the reactor. The cathode overpotential was dependent on the catholyte (sodium bicarbonate) concentration, but not the salinity ratio, indicating high catholyte conductivity was essential for maximizing hydrogen production rates. The direction of the HC and LC flows (co- or counter-current) did not affect performance in terms of hydrogen gas volume, production rates, or stack voltages. These results show that the MREC can be successfully operated using ammonium bicarbonate salts that can be regenerated using conventional distillation technologies and waste heat making the MREC a useful method for hydrogen gas production from wastes. © 2012 American Chemical Society.

  20. Hydrogen generation in microbial reverse-electrodialysis electrolysis cells using a heat-regenerated salt solution.

    Science.gov (United States)

    Nam, Joo-Youn; Cusick, Roland D; Kim, Younggy; Logan, Bruce E

    2012-05-01

    Hydrogen gas can be electrochemically produced in microbial reverse-electrodialysis electrolysis cells (MRECs) using current derived from organic matter and salinity-gradient energy such as river water and seawater solutions. Here, it is shown that ammonium bicarbonate salts, which can be regenerated using low-temperature waste heat, can also produce sufficient voltage for hydrogen gas generation in an MREC. The maximum hydrogen production rate was 1.6 m(3) H(2)/m(3)·d, with a hydrogen yield of 3.4 mol H(2)/mol acetate at a salinity ratio of infinite. Energy recovery was 10% based on total energy applied with an energy efficiency of 22% based on the consumed energy in the reactor. The cathode overpotential was dependent on the catholyte (sodium bicarbonate) concentration, but not the salinity ratio, indicating high catholyte conductivity was essential for maximizing hydrogen production rates. The direction of the HC and LC flows (co- or counter-current) did not affect performance in terms of hydrogen gas volume, production rates, or stack voltages. These results show that the MREC can be successfully operated using ammonium bicarbonate salts that can be regenerated using conventional distillation technologies and waste heat making the MREC a useful method for hydrogen gas production from wastes. © 2012 American Chemical Society

  1. A generative representation for the evolution of jazz solos

    DEFF Research Database (Denmark)

    Bäckman, Kjell; Dahlstedt, Palle

    2008-01-01

    This paper describes a system developed to create computer based jazz improvisation solos. The generation of the improvisation material uses interactive evolution, based on a dual genetic representation: a basic melody line representation, with energy constraints ("rubber band") and a hierarchic...

  2. Tooth regeneration: a revolution in stomatology and evolution in regenerative medicine

    OpenAIRE

    Yildirim, Sibel; Fu, Susan Y.; Kim, Keith; Zhou, Hong; Lee, Chang Hun; Li, Ang; Kim, Sahng Gyoon; Wang, Shuang; MAO, JEREMY J.

    2011-01-01

    A tooth is a complex biological organ and consists of multiple tissues including the enamel, dentin, cementum and pulp. Tooth loss is the most common organ failure. Can a tooth be regenerated? Can adult stem cells be orchestrated to regenerate tooth structures such as the enamel, dentin, cementum and dental pulp, or even an entire tooth? If not, what are the therapeutically viable sources of stem cells for tooth regeneration? Do stem cells necessarily need to be taken out of the body, and man...

  3. Using evolution to generate sustainable malaria control with spatial repellents.

    Science.gov (United States)

    Lynch, Penelope Anne; Boots, Mike

    2016-10-25

    Evolution persistently undermines vector control programs through insecticide resistance. Here we propose a novel strategy which instead exploits evolution to generate and sustain new control tools. Effective spatial repellents are needed to keep vectors out of houses. Our approach generates such new repellents by combining a high-toxicity insecticide with a candidate repellent initially effective against only part of the vector population. By killing mosquitoes that enter treated properties the insecticide selects for vector phenotypes deflected by the repellent, increasing efficacy of the repellent against the target vector population and in turn protecting the insecticide against the spread of insecticide resistance. Using such evolved spatial repellents offers an evolutionarily sustainable, 'double-dip' system of disease control combining mortality and repellence. We formalize this idea using models which explore vector population genetics and disease transmission probabilities and show that using evolved spatial repellents is theoretically achievable, effective and sustainable.

  4. Sensory deprivation disrupts homeostatic regeneration of newly generated olfactory sensory neurons after injury in adult mice.

    Science.gov (United States)

    Kikuta, Shu; Sakamoto, Takashi; Nagayama, Shin; Kanaya, Kaori; Kinoshita, Makoto; Kondo, Kenji; Tsunoda, Koichi; Mori, Kensaku; Yamasoba, Tatsuya

    2015-02-11

    Although it is well known that injury induces the generation of a substantial number of new olfactory sensory neurons (OSNs) in the adult olfactory epithelium (OE), it is not well understood whether olfactory sensory input influences the survival and maturation of these injury-induced OSNs in adults. Here, we investigated whether olfactory sensory deprivation affected the dynamic incorporation of newly generated OSNs 3, 7, 14, and 28 d after injury in adult mice. Mice were unilaterally deprived of olfactory sensory input by inserting a silicone tube into their nostrils. Methimazole, an olfactotoxic drug, was also injected intraperitoneally to bilaterally ablate OSNs. The OE was restored to its preinjury condition with new OSNs by day 28. No significant differences in the numbers of olfactory marker protein-positive mature OSNs or apoptotic OSNs were observed between the deprived and nondeprived sides 0-7 d after injury. However, between days 7 and 28, the sensory-deprived side showed markedly fewer OSNs and mature OSNs, but more apoptotic OSNs, than the nondeprived side. Intrinsic functional imaging of the dorsal surface of the olfactory bulb at day 28 revealed that responses to odor stimulation were weaker in the deprived side compared with those in the nondeprived side. Furthermore, prevention of cell death in new neurons 7-14 d after injury promoted the recovery of the OE. These results indicate that, in the adult OE, sensory deprivation disrupts compensatory OSN regeneration after injury and that newly generated OSNs have a critical time window for sensory-input-dependent survival 7-14 d after injury. Copyright © 2015 the authors 0270-6474/15/352657-17$15.00/0.

  5. Functional salivary gland regeneration as the next generation of organ replacement regenerative therapy.

    Science.gov (United States)

    Ogawa, Miho; Tsuji, Takashi

    2015-09-01

    Oral health is maintained by the coordinated function of many organs including the teeth and salivary glands. Dysfunction of these organs causes many problems, such as dental caries, swallowing dysfunction and periodontal disease. Regenerative therapy for salivary gland tissue repair and whole-salivary gland replacement is currently considered a novel therapeutic concept that may have potential for the full recovery of salivary gland function. Salivary gland tissue stem cells are thought to be candidate cell sources for salivary gland tissue repair therapies. In addition, whole-salivary gland replacement therapy may become a novel next-generation organ regenerative therapy. Almost all organs arise from reciprocal epithelial and mesenchymal interactions of the germ layers. We developed a novel bioengineering method, an organ germ method that can reproduce organogenesis through the epithelial-mesenchymal interaction. A bioengineered salivary gland germ can regenerate a structurally correct salivary gland in vitro, and bioengineered salivary glands successfully secrete saliva into the oral cavity from ducts in the recipient through the reestablishment of the afferent-efferent neural network. The bioengineered salivary gland can also improve the symptoms of xerostomia, such as bacterial infection and swallowing dysfunction. In this review, we describe recent findings and technological developments of salivary gland regenerative therapy.

  6. Kinetic and hydrodynamic study of absorption of H{sub 2}S from coal gas with regenerable solid sorbent for advanced power generation systems

    Energy Technology Data Exchange (ETDEWEB)

    Perales, F.; Velo, E.; Puigianer, L. [Polytechnique Univ. of Catalunya, Barcelona (Spain). Dept. of Chemical Engineering

    2003-07-01

    Compared to conventional integrated gasification combined cycle (IGCC) systems used in thermal power plants, hot gas cleanup could increase the thermal efficiency of power generating systems while decreasing the capital cost. Hot gas cleanup also plays a significant role in advanced carbon dioxide control. In this study, absorbed hydrogen sulfide (H{sub 2}S) from coal gas, suitable for IGCC plants, was treated with a regenerable solid zinc titanate sorbent in a bubbling fluidized bed reactor. Reaction kinetics were determined in a previous study using thermogravimetric analysis. A mathematical model was developed to include heterogeneous gas-solid reactions, demonstrating the evolution of the zinc titanate structure. Zinc titanate reduced exhaust concentrations from the bubbling fluidized bed to levels that will be demanded by future regulations. It was concluded that 100 per cent elimination of pollutants requires low solid conversion operating conditions.

  7. An Evolution Based Biosensor Receptor DNA Sequence Generation Algorithm

    Directory of Open Access Journals (Sweden)

    Yupeng Zang

    2009-12-01

    Full Text Available A biosensor is composed of a bioreceptor, an associated recognition molecule, and a signal transducer that can selectively detect target substances for analysis. DNA based biosensors utilize receptor molecules that allow hybridization with the target analyte. However, most DNA biosensor research uses oligonucleotides as the target analytes and does not address the potential problems of real samples. The identification of recognition molecules suitable for real target analyte samples is an important step towards further development of DNA biosensors. This study examines the characteristics of DNA used as bioreceptors and proposes a hybrid evolution-based DNA sequence generating algorithm, based on DNA computing, to identify suitable DNA bioreceptor recognition molecules for stable hybridization with real target substances. The Traveling Salesman Problem (TSP approach is applied in the proposed algorithm to evaluate the safety and fitness of the generated DNA sequences. This approach improves efficiency and stability for enhanced and variable-length DNA sequence generation and allows extension to generation of variable-length DNA sequences with diverse receptor recognition requirements.

  8. An evolution based biosensor receptor DNA sequence generation algorithm.

    Science.gov (United States)

    Kim, Eungyeong; Lee, Malrey; Gatton, Thomas M; Lee, Jaewan; Zang, Yupeng

    2010-01-01

    A biosensor is composed of a bioreceptor, an associated recognition molecule, and a signal transducer that can selectively detect target substances for analysis. DNA based biosensors utilize receptor molecules that allow hybridization with the target analyte. However, most DNA biosensor research uses oligonucleotides as the target analytes and does not address the potential problems of real samples. The identification of recognition molecules suitable for real target analyte samples is an important step towards further development of DNA biosensors. This study examines the characteristics of DNA used as bioreceptors and proposes a hybrid evolution-based DNA sequence generating algorithm, based on DNA computing, to identify suitable DNA bioreceptor recognition molecules for stable hybridization with real target substances. The Traveling Salesman Problem (TSP) approach is applied in the proposed algorithm to evaluate the safety and fitness of the generated DNA sequences. This approach improves efficiency and stability for enhanced and variable-length DNA sequence generation and allows extension to generation of variable-length DNA sequences with diverse receptor recognition requirements.

  9. Generation time and fitness tradeoffs during the evolution of multicellularity.

    Science.gov (United States)

    Leslie, Martin P; Shelton, Deborah E; Michod, Richard E

    2017-10-07

    The evolution of multicellular organisms from their unicellular ancestors is an example of an evolutionary transition in individuality (ETI), i.e. a change in the units of selection and adaptation. The theory of ETIs poses particular challenges because, by definition, key theoretical constructs such as fitness are shifting during an ETI. Past work emphasized the importance of life history tradeoffs during ETIs in which lower level units form groups and become individuals at a higher level. In particular, it has been hypothesized that the convexity of the lower-level tradeoff between viability and fecundity changes with group size and determines the optimality of lower-level specialization in the fitness components of the group. This is important because lower-level specialization is a key indicator of higher-level individuality. Here we show that increasing generation time can increase the convexity of the lower-level viability-fecundity tradeoff. This effect is a novel hypothesis for the positive association between cell-group size and cellular specialization in a major model system for ETIs, the volvocine algae. The pattern in this clade is thought to be an example of a more general size-complexity rule. Our hypothesis is that larger groups have longer generation times and longer generation times lead to more convex lower-level viability-fecundity tradeoffs, which could account for specialization being optimal only in larger cell groups (colonies). We discuss the robustness of this effect to various changes in the assumptions of our model. Our work is important for the study of ETIs in general because viability and fecundity are fundamental components of fitness in all systems and because generation time is expected to be changing during many ETIs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Temporal Evolution of Water Use for Thermoelectric Generation

    Science.gov (United States)

    Reedy, R. C.; Scanlon, B. R.

    2013-12-01

    than that of traditional coal, nuclear, or natural gas steam turbine generators with mostly cooling ponds. The primary control on water withdrawals is cooling system, with ~ two orders of magnitude lower withdrawals for cooling towers relative to once-through ponds statewide. Increases in natural gas combined cycle plants with cooling towers in response to high production of low-cost natural gas has greatly reduced water demand for thermoelectric cooling since 2000. A similar approach will be applied to thermoelectric generation throughout the US using information on fuel sources, generator technologies and cooling systems to better understand current water use for thermoelectric generation based on the legacy of past drivers and long lifespans of power plants. Understanding the historical evolution of water needs for thermoelectricity should allow us to better project future water needs.

  11. Planarian Hh signaling regulates regeneration polarity and links Hh pathway evolution to cilia.

    Science.gov (United States)

    Rink, Jochen C; Gurley, Kyle A; Elliott, Sarah A; Sánchez Alvarado, Alejandro

    2009-12-04

    The Hedgehog (Hh) signaling pathway plays multiple essential roles during metazoan development, homeostasis, and disease. Although core protein components are highly conserved, the variations in Hh signal transduction mechanisms exhibited by existing model systems (Drosophila, fish, and mammals) are difficult to understand. We characterized the Hh pathway in planarians. Hh signaling is essential for establishing the anterior/posterior axis during regeneration by modulating wnt expression. Moreover, RNA interference methods to reduce signal transduction proteins Cos2/Kif27/Kif7, Fused, or Iguana do not result in detectable Hh signaling defects; however, these proteins are essential for planarian ciliogenesis. Our study expands the understanding of Hh signaling in the animal kingdom and suggests an ancestral mechanistic link between Hh signaling and the function of cilia.

  12. EVOLUTION IN SCHOOL: REGENERATION OF THE LIBERAL REPUBLIC (1880-1930

    Directory of Open Access Journals (Sweden)

    Leonardo Tovar Bernal

    2016-09-01

    Full Text Available This article tries to clarify, based on the analysis of some representative texts from the time, the way that the evolution´s notions were materialized on classroom during the conservative dominance of the late nineteenth and early twentieth century, before liberalism took power again in 1930. It is not a definitive study; much less, intended to exhaust the topic. It describes a scene about the reaction, not infrequently acrimonious, that evolution and those explanations did not contemplate the divine idea faced within education profoundly affected by Catholic dogma. It also tries to explain the convoluted situation of this case, therefore, although the dominance of notions influenced by Catholicism, there was a small space for those lessons solved to the evolution, as well as others that conjugated elements of both, which is to show a problematic situation, in which the religious feud was not absolute.

  13. The Regeneration Challenge in the Developed World: Insights Generated from a Capabilities Approach Applied to the Understanding of Regeneration Efforts in Post-Industrial Cities

    Science.gov (United States)

    Cornelius, Nelarine; Trueman, Myfanwy

    2008-01-01

    An important aspect of the urban story of many cities in the developed world is their "regeneration" after many years of long-term social, economic and environmental decline. This is especially so in cities that have sought to reverse a long-standing, negative reputation and pejorative image. Based on the context of post-industrial…

  14. Understanding Cancer Genome and Its Evolution by Next Generation Sequencing

    DEFF Research Database (Denmark)

    Hou, Yong

    evolution by NGS, we first developed high throughput single cell sequencing (SCS) pipeline on whole exome and trascriptome and updated the pipeline after systematically reviewed the existed single cell whole genome amplification (WGA) and whole transcriptome amplification methods. Using SCS pipeline we...

  15. Evolution of coupled lives' dependency across generations and pricing impact

    OpenAIRE

    Luciano, E.; Spreeuw, J.; Vigna, E.

    2012-01-01

    This paper studies the dependence between coupled lives - both within and across generations - and its effects on prices of reversionary annuities in the presence of longevity risk. Longevity risk is represented via a stochastic mortality intensity. Dependence is modelled through copula functions. We consider Archimedean single and multi-parameter copulas. We find that dependence decreases when passing from older generations to younger generations. Not only the level of dependence but also it...

  16. Optical regeneration based on noise generated in bistable devices: going from 2R to 3R

    OpenAIRE

    González Marcos, Ana; Vivero Palmer, Tania Rosa; Rivas Moscoso, José Manuel; Martín Pereda, José Antonio

    2007-01-01

    In this paper we propose to employ an instability that occurs in bistable devices as a control signal at the reception stage to generate the clock signal. One of the adopted configurations is composed of two semiconductor optical amplifiers arranged in a cascaded structure. This configuration has an output equivalent to that obtained from Self-Electrooptic Effect Devices (SEEDs), and it can implement the main Boolean functions of two binary inputs. These outputs, obtained from the addition of...

  17. Generative Models in Deep Learning: Constraints for Galaxy Evolution

    Science.gov (United States)

    Turp, Maximilian Dennis; Schawinski, Kevin; Zhang, Ce; Weigel, Anna K.

    2018-01-01

    New techniques are essential to make advances in the field of galaxy evolution. Recent developments in the field of artificial intelligence and machine learning have proven that these tools can be applied to problems far more complex than simple image recognition. We use these purely data driven approaches to investigate the process of star formation quenching. We show that Variational Autoencoders provide a powerful method to forward model the process of galaxy quenching. Our results imply that simple changes in specific star formation rate and bulge to disk ratio cannot fully describe the properties of the quenched population.

  18. Modeling of a Thermoelectric Generator for Thermal Energy Regeneration in Automobiles

    Science.gov (United States)

    Tatarinov, Dimitri; Koppers, M.; Bastian, G.; Schramm, D.

    2013-07-01

    In the field of passenger transportation a reduction of the consumption of fossil fuels has to be achieved by any measures. Advanced designs of internal combustion engine have the potential to reduce CO2 emissions, but still suffer from low efficiencies in the range from 33% to 44%. Recuperation of waste heat can be achieved with thermoelectric generators (TEGs) that convert heat directly into electric energy, thus offering a less complicated setup as compared with thermodynamic cycle processes. During a specific driving cycle of a car, the heat currents and temperature levels of the exhaust gas are dynamic quantities. To optimize a thermoelectric recuperation system fully, various parameters have to be tested, for example, the electric and thermal conductivities of the TEG and consequently the heat absorbed and rejected from the system, the generated electrical power, and the system efficiency. A Simulink model consisting of a package for dynamic calculation of energy management in a vehicle, coupled with a model of the thermoelectric generator system placed on the exhaust system, determines the drive-cycle-dependent efficiency of the heat recovery system, thus calculating the efficiency gain of the vehicle. The simulation also shows the temperature drop at the heat exchanger along the direction of the exhaust flow and hence the variation of the voltage drop of consecutively arranged TEG modules. The connection between the temperature distribution and the optimal electrical circuitry of the TEG modules constituting the entire thermoelectric recuperation system can then be examined. The simulation results are compared with data obtained from laboratory experiments. We discuss error bars and the accuracy of the simulation results for practical thermoelectric systems embedded in cars.

  19. The Evolution of Random Number Generation in MUVES

    Science.gov (United States)

    2017-01-01

    3 2. Collins JC . Testing, selection, and implementation of random number genera- tors. Aberdeen Proving Ground (MD): Army Research Laboratory (US...261–269. 13, 16 5. L‘Ecuyer P. Tables of linear congruential generators of different sizes and good lattice structure. Mathematics of Computation

  20. Evolution, dissolution and reversible generation of gold and silver ...

    Indian Academy of Sciences (India)

    Unknown

    In this brief communication, we have highlighted for the first time the in situ preparation, dissolution and reversible generation of gold and silver nanoparticles from their cyano complexes by the UV-light. Here we have exhibited the preparation of gold and silver nanoparticles by UV- photoactivation method and then their ...

  1. Creating and Exploring Huge Parameter Spaces: Interactive Evolution as a Tool for Sound Generation

    DEFF Research Database (Denmark)

    Dahlstedt, Palle

    2001-01-01

    In this paper, a program is presented that applies interactive evolution to sound generation, i.e., preferred individuals are repeatedly selected from a population of genetically bred sound objects, created with various synthesis and pattern generation algorithms. This simplifies aural exploratio...

  2. Directed Evolution of DNA Polymerases for Next Generation Sequencing

    Science.gov (United States)

    Leconte, Aaron M.; Patel, Maha P.; Sass, Lauryn E.; McInerney, Peter; Jarosz, Mirna; Kung, Li; Bowers, Jayson L.; Buzby, Philip R.; Efcavitch, J. William; Romesberg, Floyd E.

    2011-01-01

    We present the application of an activity-based phage display method to identify DNA polymerases tailored for next generation sequencing applications. Using this approach, we identify a mutant of Taq DNA polymerase that incorporates the fluorophore-labeled dA, dT, dC, and dG substrates ~50 to 400-fold more efficiently into scarred primers in solution and that also demonstrates significantly improved performance under actual sequencing conditions. PMID:20629059

  3. "Simulated molecular evolution" or computer-generated artifacts?

    Science.gov (United States)

    Darius, F; Rojas, R

    1994-11-01

    1. The authors define a function with value 1 for the positive examples and 0 for the negative ones. They fit a continuous function but do not deal at all with the error margin of the fit, which is almost as large as the function values they compute. 2. The term "quality" for the value of the fitted function gives the impression that some biological significance is associated with values of the fitted function strictly between 0 and 1, but there is no justification for this kind of interpretation and finding the point where the fit achieves its maximum does not make sense. 3. By neglecting the error margin the authors try to optimize the fitted function using differences in the second, third, fourth, and even fifth decimal place which have no statistical significance. 4. Even if such a fit could profit from more data points, the authors should first prove that the region of interest has some kind of smoothness, that is, that a continuous fit makes any sense at all. 5. "Simulated molecular evolution" is a misnomer. We are dealing here with random search. Since the margin of error is so large, the fitted function does not provide statistically significant information about the points in search space where strings with cleavage sites could be found. This implies that the method is a highly unreliable stochastic search in the space of strings, even if the neural network is capable of learning some simple correlations. 6. Classical statistical methods are for these kind of problems with so few data points clearly superior to the neural networks used as a "black box" by the authors, which in the way they are structured provide a model with an error margin as large as the numbers being computed.7. And finally, even if someone would provide us with a function which separates strings with cleavage sites from strings without them perfectly, so-called simulated molecular evolution would not be better than random selection.Since a perfect fit would only produce exactly ones or

  4. Wind Power Generation in India: Evolution, Trends and Prospects

    Directory of Open Access Journals (Sweden)

    M.F. Khan

    2013-10-01

    Full Text Available In the present context of shrinking conventional resources coupled with environmental perils, the wind power offers an attractive alternative. Wind power generation in India started way back in early 1980s with the installation of experimental wind turbines in western and southern states of Gujarat and Tamil Nadu. For first two decades of its existence until about 2000 the progress was slow but steady. In last one decade Indian wind electricity sector has grown at very rapid pace which has promoted the country to the fifth position as largest wind electric power generator and the third largest market in the world. The galvanization of wind sector has been achieved through some aggressive policy mechanisms and persistent support by government organizations such as MNRE and C-WET. This paper articulates the journey of Indian wind program right since its inception to the present trends and developments as well as the future prospects. Keywords: mnre, c-wet, renewable energy, wind power, wind turbines.

  5. Environmental conflicts, research projects and the generation of collective expectations: a case study of a land regeneration project in Tuzla, Bosnia and Herzegovina.

    Science.gov (United States)

    Broto, Vanesa Castan

    2012-05-01

    Locally based research projects may generate multiple and competing expectations from local actors, particularly when they deal with local issues that are perceived as affecting the local quality of life, such as land regeneration. The sociology of expectations provides an entry point through which the expectations of research projects in the context of an environmental conflict can be investigated. This article analyzes a case study of a project (RECOAL) whose remit was to develop regeneration solutions for coal ash disposal sites in the western Balkans.The sociology of expectations is applied here to explain the linkage between the emergence of political discourses and collective expectations. The analysis suggests that the emergence of collective future orientations of locally based research projects needs to be understood with reference to the specific political positions from which such orientations are expressed. While expectations may shape the political debate, the political debate is also generative of such expectations.

  6. Structural evolution of regenerated silk fibroin under shear: Combined wide- and small-angle x-ray scattering experiments using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rossle, Manfred [European Molecular Biology Laboratory (EMBL), France; Panine, Pierre [European Synchrotron Radiation Facility (ESRF); Urban, Volker S [ORNL; Riekel, Christine [European Synchrotron Radiation Facility (ESRF)

    2004-04-01

    The structural evolution of regenerated Bombyx mori silk fibroin during shearing with a Couette cell has been studied in situ by synchrotron radiation small- and wide-angle x-ray scattering techniques. An elongation of fibroin molecules was observed with increasing shear rate, followed by an aggregation phase. The aggregates were found to be amorphous with {beta}-conformation according to infrared spectroscopy. Scanning x-ray microdiffraction with a 5 {micro}m beam on aggregated material, which had solidified in air, showed silk II reflections and a material with equatorial reflections close to the silk I structure reflections, but with strong differences in reflection intensities. This silk I type material shows up to two low-angle peaks suggesting the presence of water molecules that might be intercalated between hydrogen-bonded sheets.

  7. Retina regeneration in zebrafish.

    Science.gov (United States)

    Wan, Jin; Goldman, Daniel

    2016-10-01

    Unlike mammals, zebrafish are able to regenerate a damaged retina. Key to this regenerative response are Müller glia that respond to retinal injury by undergoing a reprogramming event that allows them to divide and generate a retinal progenitor that is multipotent and responsible for regenerating all major retinal neuron types. The fish and mammalian retina are composed of similar cell types with conserved function. Because of this it is anticipated that studies of retina regeneration in fish may suggest strategies for stimulating Müller glia reprogramming and retina regeneration in mammals. In this review we describe recent advances and future directions in retina regeneration research using zebrafish as a model system. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Limb regeneration.

    Science.gov (United States)

    Simon, András; Tanaka, Elly M

    2013-01-01

    Limb regeneration is observed in certain members of the animal phyla. Some animals keep this ability during their entire life while others lose it at some time during development. How do animals regenerate limbs? Is it possible to find unifying, conserved mechanisms of limb regeneration or have different species evolved distinct means of replacing a lost limb? How is limb regeneration similar or different to limb development? Studies on many organisms, including echinoderms, arthropods, and chordates have provided significant knowledge about limb regeneration. In this focus article, we concentrate on tetrapod limb regeneration as studied in three model amphibians: newts, axolotls, and frogs. We review recent progress on tissue interactions during limb regeneration, and place those findings into an evolutionary context. Copyright © 2012 Wiley Periodicals, Inc.

  9. APPLICATION OF RESTART COVARIANCE MATRIX ADAPTATION EVOLUTION STRATEGY (RCMA-ES TO GENERATION EXPANSION PLANNING PROBLEM

    Directory of Open Access Journals (Sweden)

    K. Karthikeyan

    2012-10-01

    Full Text Available This paper describes the application of an evolutionary algorithm, Restart Covariance Matrix Adaptation Evolution Strategy (RCMA-ES to the Generation Expansion Planning (GEP problem. RCMA-ES is a class of continuous Evolutionary Algorithm (EA derived from the concept of self-adaptation in evolution strategies, which adapts the covariance matrix of a multivariate normal search distribution. The original GEP problem is modified by incorporating Virtual Mapping Procedure (VMP. The GEP problem of a synthetic test systems for 6-year, 14-year and 24-year planning horizons having five types of candidate units is considered. Two different constraint-handling methods are incorporated and impact of each method has been compared. In addition, comparison and validation has also made with dynamic programming method.

  10. Cultural Transmission and Evolution of Melodic Structures in Multi-generational Signaling Games

    DEFF Research Database (Denmark)

    Lumaca, Massimo; Baggio, G.

    2017-01-01

    and cognitive constraints similarly affect the evolution of musical systems? We conducted an experiment on the cultural evolution of artificial melodic systems, using multi-generational signaling games as a laboratory model of cultural transmission. Signaling systems, using five-tone sequences as signals......It has been proposed that languages evolve by adapting to the perceptual and cognitive constraints of the human brain, developing, in the course of cultural transmission, structural regularities that maximize or optimize learnability and ease of processing. To what extent would perceptual......, and basic and compound emotions as meanings, were transmitted from senders to receivers along diffusion chains in which the receiver in each game became the sender in the next game. During transmission, structural regularities accumulated in the signaling systems, following principles of proximity, symmetry...

  11. Parameter optimization of differential evolution algorithm for automatic playlist generation problem

    Science.gov (United States)

    Alamag, Kaye Melina Natividad B.; Addawe, Joel M.

    2017-11-01

    With the digitalization of music, the number of collection of music increased largely and there is a need to create lists of music that filter the collection according to user preferences, thus giving rise to the Automatic Playlist Generation Problem (APGP). Previous attempts to solve this problem include the use of search and optimization algorithms. If a music database is very large, the algorithm to be used must be able to search the lists thoroughly taking into account the quality of the playlist given a set of user constraints. In this paper we perform an evolutionary meta-heuristic optimization algorithm, Differential Evolution (DE) using different combination of parameter values and select the best performing set when used to solve four standard test functions. Performance of the proposed algorithm is then compared with normal Genetic Algorithm (GA) and a hybrid GA with Tabu Search. Numerical simulations are carried out to show better results from Differential Evolution approach with the optimized parameter values.

  12. Use of erroneous wolf generation time in assessments of domestic dog and human evolution

    Science.gov (United States)

    Mech, L. David; Barber-meyer, Shannon

    2017-01-01

    Scientific interest in dog domestication and parallel evolution of dogs and humans (Wang et al. 2013) has increased recently (Freedman et al. 2014, Larson and Bradley 2014, Franz et al. 2016,), and various important conclusions have been drawn based on how long ago the calculations show dogs were domesticated from ancestral wolves (Canis lupus). Calculation of this duration is based on “the most commonly assumed mutation rate of 1 x 10-8 per generation and a 3-year gray wolf generation time . . .” (Skoglund et al. 2015:3). It is unclear on what information the assumed generation time is based, but Ersmark et al. (2016) seemed to have based their assumption on a single wolf (Mech and Seal 1987). The importance of assuring that such assumptions are valid is obvious. Recently, two independent studies employing three large data sets and three methods from two widely separated areas have found that wolf generation time is 4.2-4.7 years. The first study, based on 200 wolves in Yellowstone National Park used age-specific birth and death rates to calculate a generation time of 4.16 years (vonHoldt et al. 2008). The second, using estimated first-breeding times of 86 female wolves in northeastern Minnesota found a generation time of 4.3 years and using uterine examination of 159 female wolves from throughout Minnesota yielded a generation time of 4.7 years (Mech et al. 2016). We suggest that previous studies using a 3-year generation time recalculate their figures and adjust their conclusions based on these generation times and publish revised results.

  13. Physical experiments and analysis on the generation and evolution of tsunami-induced turbulent coherent structures

    Science.gov (United States)

    Kalligeris, Nikos; Lynett, Patrick

    2017-11-01

    Numerous historical accounts describe the formation of ``whirpools'' inside ports and harbors during tsunami events, causing port operation disruptions. Videos from the Japan 2011 tsunami revealed complex nearshore flow patters, resulting from the interaction of tsunami-induced currents with the man-made coastline, and the generation of large eddies (or turbulent coherent structures) in numerous ports and harbors near the earthquake epicenter. The aim of this work is to study the generation and evolution of tsunami-induced turbulent coherent structures (TCS) in a well-controlled environment using realistic scaling. A physical configuration is created in the image of a port entrance at a scale of 1:27 and a small-amplitude, long period wave creates a transient flow through the asymmetric harbor channel. A separated region forms, which coupled with the transient flow, leads to the formation of a stable monopolar TCS. The surface flow is examined through mono- and stereo-PTV techniques to extract surface velocity vectors. Surface velocity maps and vortex flow profiles are used to study the experimental TCS generation and evolution, and characterize the TCS structure. Analytical tools are used to describe the TCS growth rate and kinetic energy decay. This work was funded by the National Science Foundation NEES Research program, with Award Number 1135026.

  14. Platelet-rich fibrin: Evolution of a second-generation platelet concentrate

    Directory of Open Access Journals (Sweden)

    Sunitha Raja V

    2008-01-01

    Full Text Available Platelet-rich plasma (PRP is a platelet concentrate that has been used widely to accelerate soft-tissue and hard-tissue healing. The preparation of PRP has been described by several authors. Platelet-rich fibrin (PRF was first described by Choukroun et al. in France. It has been referred to as a second-generation platelet concentrate, which has been shown to have several advantages over traditionally prepared PRP. Its chief advantages include ease of preparation and lack of biochemical handling of blood, which makes this preparation strictly autologous. This article describes the evolution of this novel platelet concentrate, referred to as PRF.

  15. On the generation and evolution of internal solitary waves in the southern Red Sea

    KAUST Repository

    Guo, Daquan

    2015-04-01

    Satellite observations recently revealed the existence of trains of internal solitary waves in the southern Red Sea between 16.0°N and 16.5°N, propagating from the centre of the domain toward the continental shelf [Da silva et al., 2012]. Given the relatively weak tidal velocity in this area and their generation in the central of the domain, Da Silva suggested three possible mechanisms behind the generation of the waves, namely Resonance and disintegration of interfacial tides, Generation of interfacial tides by impinging, remotely generated internal tidal beams and for geometrically focused and amplified internal tidal beams. Tide analysis based on tide stations data and barotropic tide model in the Red Sea shows that tide is indeed very weak in the centre part of the Red Sea, but it is relatively strong in the northern and southern parts (reaching up to 66 cm/s). Together with extreme steep slopes along the deep trench, it provides favourable conditions for the generation of internal solitary in the southern Red Sea. To investigate the generation mechanisms and study the evolution of the internal waves in the off-shelf region of the southern Red Sea we have implemented a 2-D, high-resolution and non-hydrostatic configuration of the MIT general circulation model (MITgcm). Our simulations reproduce well that the generation process of the internal solitary waves. Analysis of the model\\'s output suggests that the interaction between the topography and tidal flow with the nonlinear effect is the main mechanism behind the generation of the internal solitary waves. Sensitivity experiments suggest that neither tidal beam nor the resonance effect of the topography is important factor in this process.

  16. A phase field crystal model simulation of morphology evolution and misfit dislocation generation in nanoheteroepitaxy

    Science.gov (United States)

    Zhang, J.; Chen, Z.; Cheng, C.; Wang, Y. X.

    2017-10-01

    A phase field crystal (PFC) model is employed to study morphology evolution of nanoheteroepitaxy and misfit dislocation generation when applied with enhanced supercooling, lattice mismatch and substrate vicinal angle conditions. Misfit strain that rises due to lattice mismatch causes rough surfaces or misfit dislocations, deteriorates film properties, hence, efforts taken to reveal their microscopic mechanism are significant for film quality improvement. Uniform islands, instead of misfit dislocations, are developed in subcritical thickness film, serving as a way of strain relief by surface mechanism. Misfit dislocations generate when strain relief by surface mechanism is deficient in higher supercooling, multilayers of misfit dislocations dominate, but the number of layers reduces gradually when the supercooling is further enhanced. Rough surfaces like islands or cuspate pits are developed which is ascribed to lattice mismatch, multilayers of misfit dislocations generate to further enhance lattice mismatch. Layers of misfit dislocations generate at a thickening position at enhanced substrate vicinal angle, this further enhancing the angle leading to sporadic generation of misfit dislocations.

  17. Effect of localized microstructural evolution on higher harmonic generation of guided wave modes

    Science.gov (United States)

    Choi, Gloria; Liu, Yang; Yao, Xiaochu; Lissenden, Cliff J.

    2015-03-01

    Higher harmonic generation of ultrasonic waves has the potential to be used to detect precursors to macroscale damage of phenomenon like fatigue due to microstructural evolution contributing to nonlinear material behavior. Aluminum plates having various plastic zone sizes were plastically deformed to different levels. The fundamental shear horizontal mode was then generated in the plate samples via a magnetostrictive transducer. After propagating through the plastic zone the primary wave mode (SH0) and its third harmonic (sh0) were received by a second transducer. Results of a parallel numerical study using the S1-s2 Lamb mode pair, where sensitivity to changes in third order elastic constants were investigated, are described within the context of the experimental results. Specimens used within both studies are geometrically similar and have double edge notches for dog bone samples that introduce localized plastic deformation. Through both studies, the size of the plastic zone with respect to the propagation distance and damage intensity influence the higher harmonics.

  18. On the generation and evolution of internal solitary waves in the southern Red Sea

    KAUST Repository

    Guo, Daquan

    2016-11-28

    Satellite observations recently revealed trains of internal solitary waves (ISWs) in the off-shelf region between 16.0 degrees N and 16.5 degrees N in the southern Red Sea. The generation mechanism of these waves is not entirely clear, though, as the observed generation sites are far away (50 km) from the shelf break and tidal currents are considered relatively weak in the Red Sea. Upon closer examination of the tide properties in the Red Sea and the unique geometry of the basin, it is argued that the steep bathymetry and a relatively strong tidal current in the southern Red Sea provide favorable conditions for the generation of ISWs. To test this hypothesis and further explore the evolution of ISWs in the basin, 2-D numerical simulations with the nonhydrostatic MIT general circulation model (MITgcm) were conducted. The results are consistent with the satellite observations in regard to the generation sites, peak amplitudes and the speeds of first-mode ISWs. Moreover, our simulations suggest that the generation process of ISWs in the southern Red Sea is similar to the tide-topography interaction mechanism seen in the South China Sea. Specifically, instead of ISWs arising in the immediate vicinity of the shelf break via a hydraulic lee wave mechanism, a broad, energetic internal tide is first generated, which subsequently travels away from the shelf break and eventually breaks down into ISWs. Sensitivity runs suggest that ISW generation may also be possible under summer stratification conditions, characterized by an intermediate water intrusion from the strait of Bab el Mandeb.

  19. On the generation and evolution of internal solitary waves in the southern Red Sea

    Science.gov (United States)

    Guo, Daquan; Akylas, T. R.; Zhan, Peng; Kartadikaria, Aditya; Hoteit, Ibrahim

    2016-12-01

    Satellite observations recently revealed trains of internal solitary waves (ISWs) in the off-shelf region between 16.0°N and 16.5°N in the southern Red Sea. The generation mechanism of these waves is not entirely clear, though, as the observed generation sites are far away (50 km) from the shelf break and tidal currents are considered relatively weak in the Red Sea. Upon closer examination of the tide properties in the Red Sea and the unique geometry of the basin, it is argued that the steep bathymetry and a relatively strong tidal current in the southern Red Sea provide favorable conditions for the generation of ISWs. To test this hypothesis and further explore the evolution of ISWs in the basin, 2-D numerical simulations with the nonhydrostatic MIT general circulation model (MITgcm) were conducted. The results are consistent with the satellite observations in regard to the generation sites, peak amplitudes and the speeds of first-mode ISWs. Moreover, our simulations suggest that the generation process of ISWs in the southern Red Sea is similar to the tide-topography interaction mechanism seen in the South China Sea. Specifically, instead of ISWs arising in the immediate vicinity of the shelf break via a hydraulic lee wave mechanism, a broad, energetic internal tide is first generated, which subsequently travels away from the shelf break and eventually breaks down into ISWs. Sensitivity runs suggest that ISW generation may also be possible under summer stratification conditions, characterized by an intermediate water intrusion from the strait of Bab el Mandeb.

  20. Large-scale Vortex Generation and Evolution in Short-crested Isolated Wave Breaking

    Science.gov (United States)

    Derakhti, M.; Kirby, J. T., Jr.

    2016-12-01

    Peregrine (1999), in discussing the effect of localization of wave energy dissipation as a generation mechanism for vorticity at the scale of individual waves, spurred a wave of study of vorticity dynamics and mixing processes in the wave-driven ocean. In deep water, the limited depth of penetration of breaking effects leads to the conceptual forcing of a "smoke-ring" resulting from the localized cross-section of impulsive forcing (Pizzo and Melville, 2013). In shallow water, depth limitations favor the generation of a quasi-two-dimensional field of vertical vortex structures, with a resulting inverse cascade of energy to low wavenumbers and the evolution of flows such as transient rip currents (Johnson and Pattiaratchi, 2006). In this study, we are examining a more detailed picture of the vorticity field evolving during a localized breaking event, with particular interest in the span from deep water to shallow water, with special attention to the transition from weak to strong bottom control. Using an LES/VOF model (Derakhti and Kirby, 2014), we examine the evolution of coherent vortex structures whose initial scales are determined by the width of the breaking region, and are much larger than the locally-controlled reverse horseshoe structures seen in typical studies of along-crest uniform breaking. We study the persistence of three-dimensionality of these structures and their contribution to the development of depth-integrated vertical vorticity, and comment on the suitability of 2D or quasi-3D models to represent nearshore flow fields.

  1. Differential evolution algorithm based automatic generation control for interconnected power systems with

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    Banaja Mohanty

    2014-09-01

    Full Text Available This paper presents the design and performance analysis of Differential Evolution (DE algorithm based Proportional–Integral (PI and Proportional–Integral–Derivative (PID controllers for Automatic Generation Control (AGC of an interconnected power system. Initially, a two area thermal system with governor dead-band nonlinearity is considered for the design and analysis purpose. In the proposed approach, the design problem is formulated as an optimization problem control and DE is employed to search for optimal controller parameters. Three different objective functions are used for the design purpose. The superiority of the proposed approach has been shown by comparing the results with a recently published Craziness based Particle Swarm Optimization (CPSO technique for the same interconnected power system. It is noticed that, the dynamic performance of DE optimized PI controller is better than CPSO optimized PI controllers. Additionally, controller parameters are tuned at different loading conditions so that an adaptive gain scheduling control strategy can be employed. The study is further extended to a more realistic network of two-area six unit system with different power generating units such as thermal, hydro, wind and diesel generating units considering boiler dynamics for thermal plants, Generation Rate Constraint (GRC and Governor Dead Band (GDB non-linearity.

  2. Cyndi: a multi-objective evolution algorithm based method for bioactive molecular conformational generation

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    Li Honglin

    2009-03-01

    Full Text Available Abstract Background Conformation generation is a ubiquitous problem in molecule modelling. Many applications require sampling the broad molecular conformational space or perceiving the bioactive conformers to ensure success. Numerous in silico methods have been proposed in an attempt to resolve the problem, ranging from deterministic to non-deterministic and systemic to stochastic ones. In this work, we described an efficient conformation sampling method named Cyndi, which is based on multi-objective evolution algorithm. Results The conformational perturbation is subjected to evolutionary operation on the genome encoded with dihedral torsions. Various objectives are designated to render the generated Pareto optimal conformers to be energy-favoured as well as evenly scattered across the conformational space. An optional objective concerning the degree of molecular extension is added to achieve geometrically extended or compact conformations which have been observed to impact the molecular bioactivity (J Comput -Aided Mol Des 2002, 16: 105–112. Testing the performance of Cyndi against a test set consisting of 329 small molecules reveals an average minimum RMSD of 0.864 Å to corresponding bioactive conformations, indicating Cyndi is highly competitive against other conformation generation methods. Meanwhile, the high-speed performance (0.49 ± 0.18 seconds per molecule renders Cyndi to be a practical toolkit for conformational database preparation and facilitates subsequent pharmacophore mapping or rigid docking. The copy of precompiled executable of Cyndi and the test set molecules in mol2 format are accessible in Additional file 1. Conclusion On the basis of MOEA algorithm, we present a new, highly efficient conformation generation method, Cyndi, and report the results of validation and performance studies comparing with other four methods. The results reveal that Cyndi is capable of generating geometrically diverse conformers and outperforms

  3. Molecular evolution of the reactive oxygen-generating NADPH oxidase (Nox/Duox family of enzymes

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    Lambeth J David

    2007-07-01

    Full Text Available Abstract Background NADPH-oxidases (Nox and the related Dual oxidases (Duox play varied biological and pathological roles via regulated generation of reactive oxygen species (ROS. Members of the Nox/Duox family have been identified in a wide variety of organisms, including mammals, nematodes, fruit fly, green plants, fungi, and slime molds; however, little is known about the molecular evolutionary history of these enzymes. Results We assembled and analyzed the deduced amino acid sequences of 101 Nox/Duox orthologs from 25 species, including vertebrates, urochordates, echinoderms, insects, nematodes, fungi, slime mold amoeba, alga and plants. In contrast to ROS defense enzymes, such as superoxide dismutase and catalase that are present in prokaryotes, ROS-generating Nox/Duox orthologs only appeared later in evolution. Molecular taxonomy revealed seven distinct subfamilies of Noxes and Duoxes. The calcium-regulated orthologs representing 4 subfamilies diverged early and are the most widely distributed in biology. Subunit-regulated Noxes represent a second major subdivision, and appeared first in fungi and amoeba. Nox5 was lost in rodents, and Nox3, which functions in the inner ear in gravity perception, emerged the most recently, corresponding to full-time adaptation of vertebrates to land. The sea urchin Strongylocentrotus purpuratus possesses the earliest Nox2 co-ortholog of vertebrate Nox1, 2, and 3, while Nox4 first appeared somewhat later in urochordates. Comparison of evolutionary substitution rates demonstrates that Nox2, the regulatory subunits p47phox and p67phox, and Duox are more stringently conserved in vertebrates than other Noxes and Nox regulatory subunits. Amino acid sequence comparisons identified key catalytic or regulatory regions, as 68 residues were highly conserved among all Nox/Duox orthologs, and 14 of these were identical with those mutated in Nox2 in variants of X-linked chronic granulomatous disease. In addition to

  4. Molecular evolution of the reactive oxygen-generating NADPH oxidase (Nox/Duox) family of enzymes

    Science.gov (United States)

    Kawahara, Tsukasa; Quinn, Mark T; Lambeth, J David

    2007-01-01

    Background NADPH-oxidases (Nox) and the related Dual oxidases (Duox) play varied biological and pathological roles via regulated generation of reactive oxygen species (ROS). Members of the Nox/Duox family have been identified in a wide variety of organisms, including mammals, nematodes, fruit fly, green plants, fungi, and slime molds; however, little is known about the molecular evolutionary history of these enzymes. Results We assembled and analyzed the deduced amino acid sequences of 101 Nox/Duox orthologs from 25 species, including vertebrates, urochordates, echinoderms, insects, nematodes, fungi, slime mold amoeba, alga and plants. In contrast to ROS defense enzymes, such as superoxide dismutase and catalase that are present in prokaryotes, ROS-generating Nox/Duox orthologs only appeared later in evolution. Molecular taxonomy revealed seven distinct subfamilies of Noxes and Duoxes. The calcium-regulated orthologs representing 4 subfamilies diverged early and are the most widely distributed in biology. Subunit-regulated Noxes represent a second major subdivision, and appeared first in fungi and amoeba. Nox5 was lost in rodents, and Nox3, which functions in the inner ear in gravity perception, emerged the most recently, corresponding to full-time adaptation of vertebrates to land. The sea urchin Strongylocentrotus purpuratus possesses the earliest Nox2 co-ortholog of vertebrate Nox1, 2, and 3, while Nox4 first appeared somewhat later in urochordates. Comparison of evolutionary substitution rates demonstrates that Nox2, the regulatory subunits p47phox and p67phox, and Duox are more stringently conserved in vertebrates than other Noxes and Nox regulatory subunits. Amino acid sequence comparisons identified key catalytic or regulatory regions, as 68 residues were highly conserved among all Nox/Duox orthologs, and 14 of these were identical with those mutated in Nox2 in variants of X-linked chronic granulomatous disease. In addition to canonical motifs, the B

  5. Adiabatic approximation for the evolution generated by an A-uniformly pseudo-Hermitian Hamiltonian

    Science.gov (United States)

    Wang, Wenhua; Cao, Huaixin; Chen, Zhengli

    2017-09-01

    We discuss an adiabatic approximation for the evolution generated by an A-uniformly pseudo-Hermitian Hamiltonian H(t). Such a Hamiltonian is a time-dependent operator H(t) similar to a time-dependent Hermitian Hamiltonian G(t) under a time-independent invertible operator A. Using the relation between the solutions of the evolution equations H(t) and G(t), we prove that H(t) and H† (t) have the same real eigenvalues and the corresponding eigenvectors form two biorthogonal Riesz bases for the state space. For the adiabatic approximate solution in case of the minimum eigenvalue and the ground state of the operator H(t), we prove that this solution coincides with the system state at every instant if and only if the ground eigenvector is time-independent. We also find two upper bounds for the adiabatic approximation error in terms of the norm distance and in terms of the generalized fidelity. We illustrate the obtained results with several examples.

  6. Evolution of In-Situ Generated Reinforcement Precipitates in Metal Matrix Composites

    Science.gov (United States)

    Sen, S.; Kar, S. K.; Catalina, A. V.; Stefanescu, D. M.; Dhindaw, B. K.

    2004-01-01

    Due to certain inherent advantages, in-situ production of Metal Matrix Composites (MMCs) have received considerable attention in the recent past. ln-situ techniques typically involve a chemical reaction that results in precipitation of a ceramic reinforcement phase. The size and spatial distribution of these precipitates ultimately determine the mechanical properties of these MMCs. In this paper we will investigate the validity of using classical growth laws and analytical expressions to describe the interaction between a precipitate and a solid-liquid interface (SLI) to predict the size and spatial evolution of the in-situ generated precipitates. Measurements made on size and distribution of Tic precipitates in a Ni&I matrix will be presented to test the validity of such an approach.

  7. DNA strand generation for DNA computing by using a multi-objective differential evolution algorithm.

    Science.gov (United States)

    Chaves-González, José M; Vega-Rodríguez, Miguel A

    2014-02-01

    In this paper, we use an adapted multi-objective version of the differential evolution (DE) metaheuristics for the design and generation of reliable DNA libraries that can be used for computation. DNA sequence design is a very relevant task in many recent research fields, e.g. nanotechnology or DNA computing. Specifically, DNA computing is a new computational model which uses DNA molecules as information storage and their possible biological interactions as processing operators. Therefore, the possible reactions and interactions among molecules must be strictly controlled to prevent incorrect computations. The design of reliable DNA libraries for bio-molecular computing is an NP-hard combinatorial problem which involves many heterogeneous and conflicting design criteria. For this reason, we modelled DNA sequence design as a multiobjective optimization problem and we solved it by using an adapted multi-objective version of DE metaheuristics. Seven different bio-chemical design criteria have been simultaneously considered to obtain high quality DNA sequences which are suitable for molecular computing. Furthermore, we have developed the multiobjective standard fast non-dominated sorting genetic algorithm (NSGA-II) in order to perform a formal comparative study by using multi-objective indicators. Additionally, we have also compared our results with other relevant results published in the literature. We conclude that our proposal is a promising approach which is able to generate reliable real-world DNA sequences that significantly improve other DNA libraries previously published in the literature. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Mass exchange in an experimental new-generation life support system model based on biological regeneration of environment

    Science.gov (United States)

    Tikhomirov, A. A.; Ushakova, S. A.; Manukovsky, N. S.; Lisovsky, G. M.; Kudenko, Yu. A.; Kovalev, V. S.; Gubanov, V. G.; Barkhatov, Yu. V.; Gribovskaya, I. V.; Zolotukhin, I. G.; Gros, J. B.; Lasseur, Ch.

    An experimental model of a biological life support system was used to evaluate qualitative and quantitative parameters of the internal mass exchange. The photosynthesizing unit included the higher plant component (wheat and radish), and the heterotrophic unit consisted of a soil-like substrate, California warms, mushrooms and microbial microflora. The gas mass exchange involved evolution of oxygen by the photosynthesizing component and its uptake by the heterotroph component along with the formation and maintaining of the SLS structure, growth of mushrooms and California worms, human respiration, and some other processes. Human presence in the system in the form of "virtual human" that at regular intervals took part in the respirative gas exchange during the experiment. Experimental data demonstrated good oxygen/carbon dioxide balance, and the closure of the cycles of these gases was almost complete. The water cycle was nearly 100% closed. The main components in the water mass exchange were transpiration water and the watering solution with mineral elements. Human consumption of the edible plant biomass (grains and roots) was simulated by processing these products by a unique physicochemical method of oxidizing them to inorganic mineral compounds, which were then returned into the system and fully assimilated by the plants. The oxidation was achieved by "wet combustion" of organic biomass, using hydrogen peroxide following a special procedure, which does not require high temperature and pressure. Hydrogen peroxide is produced from the water inside the system. The closure of the cycle was estimated for individual elements and compounds. Stoichiometric proportions are given for the main components included in the experimental model of the system. Approaches to the mathematical modeling of the cycling processes are discussed, using the data of the experimental model. Nitrogen, as a representative of biogmic elements, shows an almost 100% closure of the cycle inside

  9. Cyclical generation and degeneration of organs in a colonial urochordate involves crosstalk between old and new: a model for development and regeneration.

    Science.gov (United States)

    Lauzon, Robert J; Ishizuka, Katherine J; Weissman, Irving L

    2002-09-15

    Botryllus schlosseri is a colonial marine urochordate in which all adult organisms (called zooids) in a colony die synchronously by apoptosis (programmed cell death) in cyclical fashion. During this death phase called takeover, cell corpses within the dying organism are engulfed by circulating phagocytic cells. The "old" zooids and their organs are resorbed within 24-36 h (programmed cell removal). This process coincides temporally with the growth of asexually derived primary buds, that harbor a small number of undifferentiated cells, into mature zooids containing functional organs and tissues with the same body plan as adult zooids from which they budded. Within these colonies, all zooids share a ramifying network of extracorporeal blood vessels embedded in a gelatinous tunic. The underlying mechanisms regulating programmed cell death and programmed cell removal in this organism are unknown. In this study, we extirpated buds or zooids from B. schlosseri colonies in order to investigate the interplay that exists between buds, zooids, and the vascular system during takeover. Our findings indicate that, in the complete absence of buds (budectomy), organs from adult zooids underwent programmed cell death but were markedly impaired in their ability to be resorbed despite engulfment of zooid-derived cell corpses by phagocytes. However, when buds were removed from only half of the flower-shaped systems of zooids in a colony (hemibudectomy), the budectomized zooids were completely resorbed within 36-48 h following onset of programmed cell death. Furthermore, if hemibudectomies were carried out by using small colonies, leaving only a single functional bud, zooids from the old generation were also resorbed, albeit delayed to 48-60 h following onset of programmed cell death. This bud eventually reached functional maturity, but grew significantly larger in size than any control zooid, and exhibited hyperplasia. This finding strongly suggested that components of the dying

  10. Next generation seismic fragility curves for California bridges incorporating the evolution in seismic design philosophy

    Science.gov (United States)

    Ramanathan, Karthik Narayan

    Quantitative and qualitative assessment of the seismic risk to highway bridges is crucial in pre-earthquake planning, and post-earthquake response of transportation systems. Such assessments provide valuable knowledge about a number of principal effects of earthquakes such as traffic disruption of the overall highway system, impact on the regions’ economy and post-earthquake response and recovery, and more recently serve as measures to quantify resilience. Unlike previous work, this study captures unique bridge design attributes specific to California bridge classes along with their evolution over three significant design eras, separated by the historic 1971 San Fernando and 1989 Loma Prieta earthquakes (these events affected changes in bridge seismic design philosophy). This research developed next-generation fragility curves for four multispan concrete bridge classes by synthesizing new knowledge and emerging modeling capabilities, and by closely coordinating new and ongoing national research initiatives with expertise from bridge designers. A multi-phase framework was developed for generating fragility curves, which provides decision makers with essential tools for emergency response, design, planning, policy support, and maximizing investments in bridge retrofit. This framework encompasses generational changes in bridge design and construction details. Parameterized high-fidelity three-dimensional nonlinear analytical models are developed for the portfolios of bridge classes within different design eras. These models incorporate a wide range of geometric and material uncertainties, and their responses are characterized under seismic loadings. Fragility curves were then developed considering the vulnerability of multiple components and thereby help to quantify the performance of highway bridge networks and to study the impact of seismic design principles on the performance within a bridge class. This not only leads to the development of fragility relations

  11. The evolution of trans-generational altruism: kin selection meets niche construction.

    Science.gov (United States)

    Lehmann, L

    2007-01-01

    A cornerstone result of sociobiology states that limited dispersal can induce kin competition to offset the kin selected benefits of altruism. Several mechanisms have been proposed to circumvent this dilemma but all assume that actors and recipients of altruism interact during the same time period. Here, this assumption is relaxed and a model is developed where individuals express an altruistic act, which results in posthumously helping relatives living in the future. The analysis of this model suggests that kin selected benefits can then feedback on the evolution of the trait in a way that promotes altruistic helping at high rates under limited dispersal. The decoupling of kin competition and kin selected benefits results from the fact that by helping relatives living in the future, an actor is helping individuals that are not in direct competition with itself. A direct consequence is that behaviours which actors gain by reducing the common good of present and future generations can be opposed by kin selection. The present model integrates niche-constructing traits with kin selection theory and delineates demographic and ecological conditions under which altruism can be selected for; and conditions where the 'tragedy of the commons' can be reduced.

  12. The generation and re-generation of social capital and enterprises in multi-stakeholders social cooperative enterprises: a system dynamic approach

    Directory of Open Access Journals (Sweden)

    Claudio Travaglini

    2012-09-01

    Full Text Available Theories on social capital and on social entrepreneurship have mainly highlighted the attitude of social capital to generate enterprises and to foster good relations between third sector organizations and the public sector. This paper considers the social capital in a specific third sector enterprise; here, multi-stakeholder social cooperatives are seen, at the same time, as social capital results, creators and incubators. In the particular enterprises that identify themselves as community social enterprises, social capital, both as organizational and relational capital, is fundamental: SCEs arise from but also produce and disseminate social capital. This paper aims to improve the building of relational social capital and the refining of helpful relations drawn from other arenas, where they were created and from where they are sometimes transferred to other realities, where their role is carried on further (often working in non-profit, horizontally and vertically arranged groups, where they share resources and relations. To represent this perspective, we use a qualitative system dynamic approach in which social capital is measured using proxies. Cooperation of volunteers, customers, community leaders and third sector local organizations is fundamental to establish trust relations between public local authorities and cooperatives. These relations help the latter to maintain long-term contracts with local authorities as providers of social services and enable them to add innovation to their services, by developing experiences and management models and maintaining an interchange with civil servants regarding these matters. The long-term relations and the organizational relations linking SCEs and public organizations help to create and to renovate social capital. Thus, multi-stakeholder cooperatives originated via social capital developed in third sector organizations produce new social capital within the cooperatives themselves and between

  13. Evolution

    Science.gov (United States)

    Peter, Ulmschneider

    When we are looking for intelligent life outside the Earth, there is a fundamental question: Assuming that life has formed on an extraterrestrial planet, will it also develop toward intelligence? As this is hotly debated, we will now describe the development of life on Earth in more detail in order to show that there are good reasons why evolution should culminate in intelligent beings.

  14. Periodontal regeneration.

    Science.gov (United States)

    Ivanovski, S

    2009-09-01

    The ultimate goal of periodontal therapy is the regeneration of the tissues destroyed as a result of periodontal disease. Currently, two clinical techniques, based on the principles of "guided tissue regeneration" (GTR) or utilization of the biologically active agent "enamel matrix derivative" (EMD), can be used for the regeneration of intrabony and Class II mandibular furcation periodontal defects. In cases where additional support and space-making requirements are necessary, both of these procedures can be combined with a bone replacement graft. There is no evidence that the combined use of GTR and EMD results in superior clinical results compared to the use of each material in isolation. Great variability in clinical outcomes has been reported in relation to the use of both EMD and GTR, and these procedures can be generally considered to be unpredictable. Careful case selection and treatment planning, including consideration of patient, tooth, site and surgical factors, is required in order to optimize the outcomes of treatment. There are limited data available for the clinical effectiveness of other biologically active molecules, such as growth factors and platelet concentrates, and although promising results have been reported, further clinical trials are required in order to confirm their effectiveness. Current active areas of research are centred on tissue engineering and gene therapy strategies which may result in more predictable regenerative outcomes in the future.

  15. Plasticity and regeneration of gonads in the annelid Pristina leidyi

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    B. Duygu Özpolat

    2016-10-01

    Full Text Available Abstract Background Gonads are specialized gamete-producing structures that, despite their functional importance, are generated by diverse mechanisms across groups of animals and can be among the most plastic organs of the body. Annelids, the segmented worms, are a group in which gonads have been documented to be plastic and to be able to regenerate, but little is known about what factors influence gonad development or how these structures regenerate. In this study, we aimed to identify factors that influence the presence and size of gonads and to investigate gonad regeneration in the small asexually reproducing annelid, Pristina leidyi. Results We found that gonad presence and size in asexual adult P. leidyi are highly variable across individuals and identified several factors that influence these structures. An extrinsic factor, food availability, and two intrinsic factors, individual age and parental age, strongly influence the presence and size of gonads in P. leidyi. We also found that following head amputation in this species, gonads can develop by morphallactic regeneration in previously non-gonadal segments. We also identified a sexually mature individual from our laboratory culture that demonstrates that, although our laboratory strain reproduces only asexually, it retains the potential to become fully sexual. Conclusions Our findings demonstrate that gonads in P. leidyi display high phenotypic plasticity and flexibility with respect to their presence, their size, and the segments in which they can form. Considering our findings along with relevant data from other species, we find that, as a group, clitellate annelids can form gonads in at least four different contexts: post-starvation refeeding, fission, morphallactic regeneration, and epimorphic regeneration. This group is thus particularly useful for investigating the mechanisms involved in gonad formation and the evolution of post-embryonic phenotypic plasticity.

  16. Gene expression analysis of zebrafish heart regeneration.

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    Ching-Ling Lien

    2006-08-01

    Full Text Available Mammalian hearts cannot regenerate. In contrast, zebrafish hearts regenerate even when up to 20% of the ventricle is amputated. The mechanism of zebrafish heart regeneration is not understood. To systematically characterize this process at the molecular level, we generated transcriptional profiles of zebrafish cardiac regeneration by microarray analyses. Distinct gene clusters were identified based on temporal expression patterns. Genes coding for wound response/inflammatory factors, secreted molecules, and matrix metalloproteinases are expressed in regenerating heart in sequential patterns. Comparisons of gene expression profiles between heart and fin regeneration revealed a set of regeneration core molecules as well as tissue-specific factors. The expression patterns of several secreted molecules around the wound suggest that they play important roles in heart regeneration. We found that both platelet-derived growth factor-a and -b (pdgf-a and pdgf-b are upregulated in regenerating zebrafish hearts. PDGF-B homodimers induce DNA synthesis in adult zebrafish cardiomyocytes. In addition, we demonstrate that a chemical inhibitor of PDGF receptor decreases DNA synthesis of cardiomyocytes both in vitro and in vivo during regeneration. Our data indicate that zebrafish heart regeneration is associated with sequentially upregulated wound healing genes and growth factors and suggest that PDGF signaling is required.

  17. The thermal evolution and dynamo generation of Mercury with an Fe-Si core

    Science.gov (United States)

    Knibbe, Jurrien

    2017-04-01

    The present day partially liquid (as opposed to fully solidified) Fe-rich core of Mercury is traditionally explained by assuming a substantial amount of S to be present in the core (e.g. Grott et al., 2011), because S lowers the core's melting temperature. However, this assumption has problematic implications: Mercury's large Fe-rich core and measured low FeO surface content are indicative of an oxygen poor bulk composition, which is consistent with the volatile-poor material that is expected to have condensed from the solar nebula close to the Sun. In contrast, S is a moderately volatile element. Combined with the high S content of Mercury's crust and (likely) mantle, as indicated by the measured high S/Si surface fraction, the resulting high planetary S abundance is difficult to reconcile with a volatile poor origin of the planet. Additionally, the observed low magnetic field strength is most easily explained if compositional buoyancy fluxes are absent [Manglik et al., 2010], yet such fluxes are produced upon solidifying a pure Fe inner core from Fe-S liquid. Alternatively, both Mercury's high S/Si and Mg/Si surface ratios (Nittler et al., 2011) may indicate that a siderophile fractionation of Si and lithophile fractionation of S took place during Mercury's core-mantle differentiation. This fractionation behaviour of these elements is supported by metal/silicate partitioning experiments that have been performed at the low oxygen conditions inferred for Mercury [e.g. Chabot et al., 2014]. Mercury's bulk composition, in terms of S/Si and Fe/Si ratios, would also approach that of meteorites that are considered as potential building blocks of the planet if the core is Si-rich and S-poor. Here we simulate the thermal evolution of Mercury with an Fe-Si core. Results show that an Fe-Si core can remain largely molten until present, without the need for S. An Fe-Si core also has interesting implications for Mercury's core-convection regime and magnetic field generation

  18. Efficient regeneration of NADPH in a 3-enzyme cascade reaction by in situ generation of glucose 6-phosphate from glucose and pyrophosphate

    NARCIS (Netherlands)

    Hartog, A.F.; van Herk, T.; Wever, R.

    2011-01-01

    We report here a promising method to regenerate NADPH (nicotinamide adenine dinucleotide phosphate) using the intermediate formation of glucose 6-phosphate (G6P) from glucose and pyrophosphate (PPi) catalyzed by the acid phosphatase from Shigella flexneri (PhoN-Sf). The G6P formed is used in turn by

  19. Axon Regeneration Is Regulated by Ets-C/EBP Transcription Complexes Generated by Activation of the cAMP/Ca2+ Signaling Pathways.

    Directory of Open Access Journals (Sweden)

    Chun Li

    2015-10-01

    Full Text Available The ability of specific neurons to regenerate their axons after injury is governed by cell-intrinsic regeneration pathways. In Caenorhabditis elegans, the JNK and p38 MAPK pathways are important for axon regeneration. Axonal injury induces expression of the svh-2 gene encoding a receptor tyrosine kinase, stimulation of which by the SVH-1 growth factor leads to activation of the JNK pathway. Here, we identify ETS-4 and CEBP-1, related to mammalian Ets and C/EBP, respectively, as transcriptional activators of svh-2 expression following axon injury. ETS-4 and CEBP-1 function downstream of the cAMP and Ca2+-p38 MAPK pathways, respectively. We show that PKA-dependent phosphorylation of ETS-4 promotes its complex formation with CEBP-1. Furthermore, activation of both cAMP and Ca2+ signaling is required for activation of svh-2 expression. Thus, the cAMP/Ca2+ signaling pathways cooperatively activate the JNK pathway, which then promotes axon regeneration.

  20. The Architectural Practice of Regeneration

    Directory of Open Access Journals (Sweden)

    Tom Van Malderen

    2013-09-01

    Full Text Available In form and in content, cities are the epitome of diversity. This state is the result of the accumulation of layers of history, of construction, of demolition and reconstruction cycles. These tensions are the catalyst for the emergence of new urban forms and participate in the construction of heritage. As such they should be encouraged. As important as the existing fabric of the city is, its evolution to accommodate the ever-changing needs and fashions of its inhabitants is paramount. For regeneration to be successful it must inscribe itself in this process and it must be driven by an understanding of the environment where it occurs. This paper explores, through the lens of an architectural practice, some design processes and architectural proposals that have been generated by working on the Valletta harbours. It also discusses the necessary dynamics required to accommodate stakeholder engagement and planning policy while ensuring design quality and the perpetuation of the creative process inherent to the city. Finally, the paper introduces, as a possible future, the experiments and studies of the practice on the wider Valletta, putting into perspective the benefits of theoretical research combined with formal and aesthetic explorations of the harbour region.

  1. An ancient dental gene set governs development and continuous regeneration of teeth in sharks.

    Science.gov (United States)

    Rasch, Liam J; Martin, Kyle J; Cooper, Rory L; Metscher, Brian D; Underwood, Charlie J; Fraser, Gareth J

    2016-07-15

    The evolution of oral teeth is considered a major contributor to the overall success of jawed vertebrates. This is especially apparent in cartilaginous fishes including sharks and rays, which develop elaborate arrays of highly specialized teeth, organized in rows and retain the capacity for life-long regeneration. Perpetual regeneration of oral teeth has been either lost or highly reduced in many other lineages including important developmental model species, so cartilaginous fishes are uniquely suited for deep comparative analyses of tooth development and regeneration. Additionally, sharks and rays can offer crucial insights into the characters of the dentition in the ancestor of all jawed vertebrates. Despite this, tooth development and regeneration in chondrichthyans is poorly understood and remains virtually uncharacterized from a developmental genetic standpoint. Using the emerging chondrichthyan model, the catshark (Scyliorhinus spp.), we characterized the expression of genes homologous to those known to be expressed during stages of early dental competence, tooth initiation, morphogenesis, and regeneration in bony vertebrates. We have found that expression patterns of several genes from Hh, Wnt/β-catenin, Bmp and Fgf signalling pathways indicate deep conservation over ~450 million years of tooth development and regeneration. We describe how these genes participate in the initial emergence of the shark dentition and how they are redeployed during regeneration of successive tooth generations. We suggest that at the dawn of the vertebrate lineage, teeth (i) were most likely continuously regenerative structures, and (ii) utilised a core set of genes from members of key developmental signalling pathways that were instrumental in creating a dental legacy redeployed throughout vertebrate evolution. These data lay the foundation for further experimental investigations utilizing the unique regenerative capacity of chondrichthyan models to answer evolutionary

  2. Evolution and Morphogenesis of Simulated Modular Robots: A Comparison Between a Direct and Generative Encoding

    DEFF Research Database (Denmark)

    Veenstra, Frank; Faina, Andres; Risi, Sebastian

    2017-01-01

    Modular robots oer an important benet in evolutionary robotics, which is to quickly evaluate evolved morphologies and control systems in reality. However, articial evolution of simulated modular robotics is a dicult and time consuming task requiring signicant computational power. While articial e...

  3. How evolution generates complexity without design: language as an instructional metaphor.

    Science.gov (United States)

    Gillings, Michael R

    2012-03-01

    One of the major stumbling blocks to understanding evolution is the difficulty in reconciling the emergence of complexity with the apparently undirected forces that drive evolutionary processes. This difficulty was originally framed as the "Watch and Watchmaker" argument and more recently revived by proponents of "intelligent design." Undergraduates in particular often attribute purpose and forethought as the driving force behind biological phenomena, and have difficulty understanding evolutionary processes. To demonstrate that complexity can arise solely through mutations that fix in populations via natural selection or drift, we can use analogies where processes can be observed across short time frames and where the key data are accessible to those without specialized biological knowledge. The evolution of language provides such an example. Processes of natural selection, mutation, genetic drift, acquisition of new functions, punctuated equilibria, and lateral gene transfer can be illustrated using examples of changing spellings, neologism, and acquisition of words from other languages. The examples presented in this article are readily accessible, and demonstrate to students that languages have dynamically increased in complexity, simply driven by the usage patterns of their speakers. © 2011 The Author. Evolution© 2011 The Society for the Study of Evolution.

  4. An autologously generated platelet-rich plasma suturable membrane may enhance peripheral nerve regeneration after neurorraphy in an acute injury model of sciatic nerve neurotmesis.

    Science.gov (United States)

    Giannessi, Elisabetta; Coli, Alessandra; Stornelli, Maria Rita; Miragliotta, Vincenzo; Pirone, Andrea; Lenzi, Carla; Burchielli, Silvia; Vozzi, Giovanni; De Maria, Carmelo; Giorgetti, Margherita

    2014-11-01

    The aim of this study was to investigate the ability of suturable platelet-rich plasma (PRP) membrane to promote peripheral nerve regeneration after neurotmesis and neurorraphy. A total of 36 rats were used: 32 animals underwent surgery and were split in two groups. An interim sacrifice was performed at 6 weeks postsurgery and final sacrifice at 12 weeks; four animals did not sustain nerve injury and served as control. Clinical, electromyographic (EMG), gross, and histological changes were assessed. The EMG signal was evaluated for its amplitude and frequency spectrum. Number of regenerating fibers, their diameter, and myelin thickness were histologically analyzed. Both EMG parameters showed a significant (p < 0.05) effect of treatment at 6 and 12 weeks postsurgery. At 6 weeks, the fiber density was statistically different between treated and untreated animals with a higher observed density in treated nerves. No difference in fiber density was observed at 12 weeks postsurgery. The distribution of fiber diameters showed an effect at 12 weeks when only the sections of the nerves sutured with PRP showed fibers with diameters greater than 6 µm. Our data show that the application of a PRP fibrin membrane around the neurorraphy improves the nerve regeneration process in a rat sciatic nerve model. The use of PRP as a suturable membrane could perform an action not only as a source of bioactive proteins but also as a nerve guide to hold the scar reaction and thus improve axonal regeneration. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  5. Fast Evolution and Waveform Generator for Extreme-Mass-Ratio Inspirals in Equatorial-Circular Orbits

    CERN Document Server

    Han, Wen-Biao

    2016-01-01

    In this paper we discuss the development of a fast and accurate waveform model for the quasi-circular orbital evolution of extreme-mass-ratio-inspirals (EMRIs). This model simply employs the data of a few numerical Teukoulsky-based energy fluxes and waveforms to fit out a set of polynomials for the entire fluxes and waveforms. These obtained polynomials are accurate enough in the entire evolution domain, and much more accurate than the resummation post-Newtonian (PN) energy fluxes and waveforms, especially when the spin of a black hole becomes large. The dynamical equation we adopted for orbital revolution is the effective-one-body (EOB) formalism. Because of the simplified expressions, the efficiency of calculating the orbital evolution with our polynomials is also better than the traditional method which uses the resummed PN analytical fluxes. Our model should be useful in calculation of waveform templates of EMRIs for the gravitational wave detectors such as the evolved Laser Interferometer Space Antenna (...

  6. A generation-time effect on the rate of molecular evolution in bacteria.

    Science.gov (United States)

    Weller, Cory; Wu, Martin

    2015-03-01

    Molecular evolutionary rate varies significantly among species and a strict global molecular clock has been rejected across the tree of life. Generation time is one primary life-history trait that influences the molecular evolutionary rate. Theory predicts that organisms with shorter generation times evolve faster because of the accumulation of more DNA replication errors per unit time. Although the generation-time effect has been demonstrated consistently in plants and animals, the evidence of its existence in bacteria is lacking. The bacterial phylum Firmicutes offers an excellent system for testing generation-time effect because some of its members can enter a dormant, nonreproductive endospore state in response to harsh environmental conditions. It follows that spore-forming bacteria would--with their longer generation times--evolve more slowly than their nonspore-forming relatives. It is therefore surprising that a previous study found no generation-time effect in Firmicutes. Using a phylogenetic comparative approach and leveraging on a large number of Firmicutes genomes, we found sporulation significantly reduces the genome-wide spontaneous DNA mutation rate and protein evolutionary rate. Contrary to the previous study, our results provide strong evidence that the evolutionary rates of bacteria, like those of plants and animals, are influenced by generation time. © 2015 The Author(s).

  7. Evolution of fluid-like granular ejecta generated by sphere impact

    KAUST Repository

    Marston, Jeremy

    2012-05-01

    We present results from an experimental study of the speed and shape of the ejecta formed when a solid sphere impacts onto a granular bed. We use high-speed imaging at frame rates up to 100 000 f.p.s. to provide direct measurement of individual grain velocities and ejecta angles as well as the overall evolution of the granular ejecta. For larger grain sizes, the emergence velocities of the grains during the early stage flow, i.e. before the main ejecta curtain forms, increase with the kinetic energy of the impacting sphere but are inversely proportional to the time from impact. We also observe that the fastest grains, which can obtain velocities up to five times that of the impacting sphere (V g/V 0 = 5), generally emerge at the earliest times and with the lowest ejection angles. As the grain size is decreased, a more fluid-like behaviour is observed whereby the ejected material first emerges as a thin sheet of grains between the sphere and the bed surface, which is also seen when a sphere impacts a liquid pool. In this case, the sheet velocity is approximately double that of the impacting sphere (V s/V 0 = 2) and independent of the bulk packing fraction. For the finest grains we provide evidence of the existence of a vortex ring inside the ejecta curtain where grains following the air flow are entrained through the curtain. In contrast to predictions from previous studies, we find that the temporal evolution of the ejecta neck radius is not initially quadratic but rather approaches a square-root dependence on time, for the finest grains with the highest impact kinetic energy. The evolution therefore approaches that seen for the crown evolution in liquid drop impacts. By using both spherical glass beads and coarse sands, we show that the size and shape distribution are critical in determining the post-impact dynamics whereby the sands exhibit a qualitatively different response to impact, with grains ejected at lower speeds and at later times than for the glass

  8. Evolution of First-generation and Second-generation Antipsychotic Prescribing Patterns in Belgium Between 1997 and 2012: A Population-based Study.

    Science.gov (United States)

    Morrens, Manuel; Destoop, Marianne; Cleymans, Stijn; VAN DER Spek, Susan; Dom, Geert

    2015-07-01

    In recent decades, a substantial increase in prescriptions of antipsychotics has been reported in several countries. This increase in antipsychotic sales has been attributed to the success of second-generation antipsychotics. This national register-based study investigated the evolution of outpatient antipsychotic sales in Belgium between 1997 and 2012. The impact of the specialization of the prescriber and the demographic characteristics of both prescribing doctors and patients were examined. The study used data obtained from the Belgian National Institute for Health and Disability Insurance and IMS Health Belgium. Over this 15-year period, antipsychotic sales increased by 122% in Belgium. This growth was mainly explained by a 3-fold increase in antipsychotic prescriptions by psychiatrists and neurologists. Overall, only 29.5% of prescriptions for antipsychotics were for psychotic disorders and only 26.2% of prescriptions for antipsychotics were for mood disorders, suggesting a large amount of off-label use. A significant shift toward second-generation agents was found in prescriptions by both psychiatrists and general practitioners, although there may have been a small delay in moving toward second-generation agents in the latter group. This increase in second-generation antipsychotic prescribing was mainly due to the steep rise in sales of quetiapine, followed by olanzapine and risperidone. The shift toward the newer products was also mainly seen in younger prescribers. The results of this study suggest that there has been an increase in adequate management of patients in need of antipsychotic treatment. Nevertheless, very few of the patients received continued treatment throughout the year, which implies that few outpatients with schizophrenia are receiving adequate treatment.

  9. Evolution of Wholesale Electricity Market Design with Increasing Levels of Renewable Generation

    Energy Technology Data Exchange (ETDEWEB)

    Ela, E.; Milligan, M.; Bloom, A.; Botterud, A.; Townsend, A.; Levin, T.

    2014-09-01

    Variable generation such as wind and photovoltaic solar power has increased substantially in recent years. Variable generation has unique characteristics compared to the traditional technologies that supply energy in the wholesale electricity markets. These characteristics create unique challenges in planning and operating the power system, and they can also influence the performance and outcomes from electricity markets. This report focuses on two particular issues related to market design: revenue sufficiency for long-term reliability and incentivizing flexibility in short-term operations. The report provides an overview of current design and some designs that have been proposed by industry or researchers.

  10. Bone regeneration during distraction osteogenesis.

    Science.gov (United States)

    Amir, Lisa R; Everts, Vincent; Bronckers, Antonius L J J

    2009-07-01

    Bone has the capacity to regenerate in response to injury. During distraction osteogenesis, the renewal of bone is enhanced by gradual stretching of the soft connective tissues in the gap area between two separated bone segments. This procedure has received much clinical attention as a way to correct congenital growth retardation of bone tissue or to generate bone to fill skeletal defects. The process of bone regeneration involves a complex system of biological changes whereby mechanical stress is converted into a cascade of signals that activate cellular behavior resulting in (enhanced) formation of bone. Over the last decade, significant progress has been made in understanding the bone regeneration process during distraction osteogenesis. The mechanical and biological factors that are important for the success of the distraction treatment have been partially characterized and are discussed in this review.

  11. From Central Pattern Generator to Sensory Template in the Evolution of Birdsong

    Science.gov (United States)

    Konishi, Masakazu

    2010-01-01

    Central nervous networks, be they a part of the human brain or a group of neurons in a snail, may be designed to produce distinct patterns of movement. Central pattern generators can account for the development and production of normal vocal signals without auditory feedback in non-songbirds. Songbirds need auditory feedback to develop and…

  12. Design Evolution and Verification of the A-3 Chemical Steam Generator

    Science.gov (United States)

    Kirchner, Casey K.

    2009-01-01

    Following is an overview of the Chemical Steam Generator system selected to provide vacuum conditions for a new altitude test facility, the A-3 Test Stand at Stennis Space Center (SSC) in Bay St. Louis, MS. A-3 will serve as NASA s primary facility for altitude testing of the J-2X rocket engine, to be used as the primary propulsion device for the upper stages of the Ares launch vehicles. The Chemical Steam Generators (CSGs) will produce vacuum conditions in the test cell through the production and subsequent supersonic ejection of steam into a diffuser downstream of the J-2X engine nozzle exit. The Chemical Steam Generators chosen have a rich heritage of operation at rocket engine altitude test facilities since the days of the Apollo program and are still in use at NASA White Sands Test Facility (WSTF) in New Mexico. The generators at WSTF have been modified to a degree, but are still very close to the heritage design. The intent for the A-3 implementation is to maintain this heritage design as much as possible, making minimal updates only where necessary to substitute for obsolete parts and to increase reliability. Reliability improvements are especially desired because the proposed system will require 27 generators, which is nine times the largest system installed in the 1960s. Improvements were suggested by the original design firm, Reaction Motors, by NASA SSC and NASA WSTF engineers, and by the A-3 test stand design contractor, Jacobs Technology, Inc. (JTI). This paper describes the range of improvements made to the design to date, starting with the heritage generator and the minor modifications made over time at WSTF, to the modernized configuration which will be used at A-3. The paper will discuss NASA s investment in modifications to SSC s E-2 test facility fire a full-scale Chemical Steam Generator in advance of the larger steam system installation at A-3. Risk mitigation testing will be performed in early 2009 at this test facility to verify that the CSGs

  13. Evolution of an impact-generated dust cloud and its effects on the atmosphere

    Science.gov (United States)

    Toon, O. B.; Pollack, J. B.; Ackerman, T. P.; Turco, R. P.; Mckay, C. P.; Liu, M. S.

    1982-01-01

    A simulation is carried out of the evolution of an optically thick dust cloud in the earth's atmosphere, and calculations are made of the effects that such a dust cloud would have on the amount of visible light reaching the surface and the temperature at the earth's surface. It is found that large quantities of dust remain in the atmosphere for periods of only three to six months. This duration is fixed by the physical processes of coagulation; these cause the rapid formation of micron-sized particles and sedimentation that quickly removes the particles from the atmosphere. The duration of the event is found to be nearly independent of the initial altitude, initial particle size, initial mass, atmospheric vertical diffusive mixing rate, and rainout rate. It depends to a slight extent on the particle density and the probability that colliding particles stick together to form a larger particle. In addition, the duration is limited by the rate at which the debris spreads from the initial impact site. A doubling code is used to calculate the visible radiative transfer in the dust clouds. It is found that light levels are too low for vision for one to six months and too low for photosynthesis for two months to one year.

  14. Evolution of a Fourth Generation Catalyst for the Amination and Thioetherification of Aryl Halides

    Science.gov (United States)

    Hartwig, John F.

    2010-01-01

    Conspectus Synthetic methods to form the carbon-nitrogen bonds in aromatic amines are fundamental enough to be considered part of introductory organic courses. Arylamines are important because they are common precursors to or substructures within active pharmaceutical ingredients and herbicides produced on ton scales, as well as conducting polymers and layers of organic light-emitting diodes produced on small scale. For many years, this class of compound was prepared from classical methods, such as nitration, reduction and reductive alkylation, copper-mediated chemistry at high temperatures, addition to benzyne intermediates, or direct nucleophilic substitution on particularly electron-poor aromatic or heteroaromatic halides. During the past decade, these methods to form aromatic amines have been largely supplanted by palladium-catalyzed coupling reactions of amines with aryl halides. The scope and efficiency of the palladium-catalyzed processes has gradually improved with successive generations of catalysts to the point of being useful for the synthesis of both milligrams and kilograms of product. This Account describes the conceptual basis and utility of our latest, “fourth-generation” catalyst for the coupling of amines and related reagents with aryl halides. The introductory sections of this account describe the progression of catalyst development from the first-generation to current systems and the motivation for selection of the components of the fourth-generation catalyst. This progression began with catalysts containing palladium and sterically hindered monodentate aromatic phosphines used initially for coupling of tin amides with haloarenes in the first work on C-N coupling. A second generation of catalysts was then developed based on the combination of palladium and aromatic bisphosphines. These systems were then followed by third-generation systems catalysts on the combination of palladium and a sterically hindered alkylmonophosphine or N

  15. Design of Spiking Central Pattern Generators for Multiple Locomotion Gaits in Hexapod Robots by Christiansen Grammar Evolution.

    Science.gov (United States)

    Espinal, Andres; Rostro-Gonzalez, Horacio; Carpio, Martin; Guerra-Hernandez, Erick I; Ornelas-Rodriguez, Manuel; Sotelo-Figueroa, Marco

    2016-01-01

    This paper presents a method to design Spiking Central Pattern Generators (SCPGs) to achieve locomotion at different frequencies on legged robots. It is validated through embedding its designs into a Field-Programmable Gate Array (FPGA) and implemented on a real hexapod robot. The SCPGs are automatically designed by means of a Christiansen Grammar Evolution (CGE)-based methodology. The CGE performs a solution for the configuration (synaptic weights and connections) for each neuron in the SCPG. This is carried out through the indirect representation of candidate solutions that evolve to replicate a specific spike train according to a locomotion pattern (gait) by measuring the similarity between the spike trains and the SPIKE distance to lead the search to a correct configuration. By using this evolutionary approach, several SCPG design specifications can be explicitly added into the SPIKE distance-based fitness function, such as looking for Spiking Neural Networks (SNNs) with minimal connectivity or a Central Pattern Generator (CPG) able to generate different locomotion gaits only by changing the initial input stimuli. The SCPG designs have been successfully implemented on a Spartan 6 FPGA board and a real time validation on a 12 Degrees Of Freedom (DOFs) hexapod robot is presented.

  16. Generation of novel AAV variants by directed evolution for improved CFTR delivery to human ciliated airway epithelium.

    Science.gov (United States)

    Li, Wuping; Zhang, Liqun; Johnson, Jarrod S; Zhijian, Wu; Grieger, Joshua C; Ping-Jie, Xiao; Drouin, Lauren M; Agbandje-McKenna, Mavis; Pickles, Raymond J; Samulski, R Jude

    2009-12-01

    Recombinant adeno-associated virus (AAV) vectors expressing the cystic fibrosis transmembrane conductance regulator (CFTR) gene have been used to deliver CFTR to the airway epithelium of cystic fibrosis (CF) patients. However, no significant CFTR function has been demonstrated likely due to low transduction efficiencies of the AAV vectors. To improve AAV transduction efficiency for human airway epithelium (HAE), we generated a chimeric AAV library and performed directed evolution of AAV on an in vitro model of human ciliated airway epithelium. Two independent and novel AAV variants were identified that contained capsid components from AAV-1, AAV-6, and/or AAV-9. The transduction efficiencies of the two novel AAV variants for human ciliated airway epithelium were three times higher than that for AAV-6. The novel variants were then used to deliver CFTR to ciliated airway epithelium from CF patients. Here we show that our novel AAV variants, but not the parental, AAV provide sufficient CFTR delivery to correct the chloride ion transport defect to ~25% levels measured in non-CF cells. These results suggest that directed evolution of AAV on relevant in vitro models will enable further improvements in CFTR gene transfer efficiency and the development of an efficacious and safe gene transfer vector for CF lung disease.

  17. The Evolution of Electrospray Generated Droplets is Not Affected by Ionization Mode

    Science.gov (United States)

    Liigand, Piia; Heering (Suu), Agnes; Kaupmees, Karl; Leito, Ivo; Girod, Marion; Antoine, Rodolphe; Kruve, Anneli

    2017-10-01

    Ionization efficiency and mechanism in ESI is strongly affected by the properties of mobile phase. The use of mobile-phase properties to accurately describe droplets in ESI source is convenient but may be inadequate as the composition of the droplets is changing in the plume due to electrochemical reactions occurring in the needle tip as well as continuous drying and fission of droplets. Presently, there is paucity of research on the effect of the polarity of the ESI mode on mobile phase composition in the droplets. In this paper, the change in the organic solvent content, pH, and droplet size are studied in the ESI plume in both ESI+ and ESI- ionization mode. We introduce a rigorous way - the absolute pH (pHabs H 2 O) - to describe pH change in the plume that takes into account organic solvent content in the mobile phase. pHabs H 2 O enables comparing acidities of ESI droplets with different organic solvent contents. The results are surprisingly similar for both ionization modes, indicating that the dynamics of the change of mobile-phase properties is independent from the ESI mode used. This allows us to conclude that the evolution of ESI droplets first of all proceeds via the evaporation of the organic modifier and to a lesser extent via fission of smaller droplets from parent droplets. Secondly, our study shows that qualitative findings related to the ESI process obtained on the ESI+ mode can almost directly be applied also in the ESI- mode. [Figure not available: see fulltext.

  18. Evolution of co-management: role of knowledge generation, bridging organizations and social learning.

    Science.gov (United States)

    Berkes, Fikret

    2009-04-01

    Over a period of some 20 years, different aspects of co-management (the sharing of power and responsibility between the government and local resource users) have come to the forefront. The paper focuses on a selection of these: knowledge generation, bridging organizations, social learning, and the emergence of adaptive co-management. Co-management can be considered a knowledge partnership. Different levels of organization, from local to international, have comparative advantages in the generation and mobilization of knowledge acquired at different scales. Bridging organizations provide a forum for the interaction of these different kinds of knowledge, and the coordination of other tasks that enable co-operation: accessing resources, bringing together different actors, building trust, resolving conflict, and networking. Social learning is one of these tasks, essential both for the co-operation of partners and an outcome of the co-operation of partners. It occurs most efficiently through joint problem solving and reflection within learning networks. Through successive rounds of learning and problem solving, learning networks can incorporate new knowledge to deal with problems at increasingly larger scales, with the result that maturing co-management arrangements become adaptive co-management in time.

  19. Automatic generation of design structure matrices through the evolution of product models

    DEFF Research Database (Denmark)

    Gopsill, James A.; Snider, Chris; McMahon, Chris

    2016-01-01

    Dealing with component interactions and dependencies remains a core and fundamental aspect of engineering, where conflicts and constraints are solved on an almost daily basis. Failure to consider these interactions and dependencies can lead to costly overruns, failure to meet requirements, and le...... sense. For these reasons, tools and methods to support the identification and monitoring of component interactions and dependencies continues to be an active area of research. In particular, design structure matrices (DSMs) have been extensively applied to identify and visualize product...... and organizational architectures across a number of engineering disciplines. However, the process of generating these DSMs has primarily used surveys, structured interviews, and/or meetings with engineers. As a consequence, there is a high cost associated with engineers' time alongside the requirement to continually...... computer-aided design, finite element analysis, and computational fluid dynamics systems. The paper shows that a DSM generated from the changes in the product models corroborates with the product architecture as defined by the engineers and results from previous DSM studies. In addition, further levels...

  20. Simulated evolution of three-dimensional magnetic nulls leading to generation of cylindrically-shaped current sheets

    Science.gov (United States)

    Kumar, Sanjay; Bhattacharyya, R.

    2017-06-01

    The performed magnetohydrodynamic simulation examines the importance of magnetofluid evolution, which naturally leads to current sheets in the presence of three-dimensional (3D) magnetic nulls. The initial magnetic field is constructed by superposing a 3D force-free field on a constant axial magnetic field. The initial field supports 3D magnetic nulls having the classical spine axis and the dome-shaped fan surface and exerts non-zero Lorentz force on the magnetofluid. Importantly, the simulation identifies the development of current sheets near the 3D magnetic nulls. The morphology of the current sheets is similar to a cylindrical surface where the surface encloses the spine axis. The development is because of favorable deformation of magnetic field lines constituting the dome-shaped fan surface. The deformation of field lines is found to be caused by the flow generated by magnetic reconnections at current sheets which are located away from the cylindrically shaped current sheets.

  1. Electrochemical generation of sulfur vacancies in the basal plane of MoS2 for hydrogen evolution

    Science.gov (United States)

    Tsai, Charlie; Li, Hong; Park, Sangwook; Park, Joonsuk; Han, Hyun Soo; Nørskov, Jens K.; Zheng, Xiaolin; Abild-Pedersen, Frank

    2017-01-01

    Recently, sulfur (S)-vacancies created on the basal plane of 2H-molybdenum disulfide (MoS2) using argon plasma exposure exhibited higher intrinsic activity for the electrochemical hydrogen evolution reaction than the edge sites and metallic 1T-phase of MoS2 catalysts. However, a more industrially viable alternative to the argon plasma desulfurization process is needed. In this work, we introduce a scalable route towards generating S-vacancies on the MoS2 basal plane using electrochemical desulfurization. Even though sulfur atoms on the basal plane are known to be stable and inert, we find that they can be electrochemically reduced under accessible applied potentials. This can be done on various 2H-MoS2 nanostructures. By changing the applied desulfurization potential, the extent of desulfurization and the resulting activity can be varied. The resulting active sites are stable under extended desulfurization durations and show consistent HER activity. PMID:28429782

  2. Electrochemical generation of sulfur vacancies in the basal plane of MoS2 for hydrogen evolution

    Science.gov (United States)

    Tsai, Charlie; Li, Hong; Park, Sangwook; Park, Joonsuk; Han, Hyun Soo; Nørskov, Jens K.; Zheng, Xiaolin; Abild-Pedersen, Frank

    2017-04-01

    Recently, sulfur (S)-vacancies created on the basal plane of 2H-molybdenum disulfide (MoS2) using argon plasma exposure exhibited higher intrinsic activity for the electrochemical hydrogen evolution reaction than the edge sites and metallic 1T-phase of MoS2 catalysts. However, a more industrially viable alternative to the argon plasma desulfurization process is needed. In this work, we introduce a scalable route towards generating S-vacancies on the MoS2 basal plane using electrochemical desulfurization. Even though sulfur atoms on the basal plane are known to be stable and inert, we find that they can be electrochemically reduced under accessible applied potentials. This can be done on various 2H-MoS2 nanostructures. By changing the applied desulfurization potential, the extent of desulfurization and the resulting activity can be varied. The resulting active sites are stable under extended desulfurization durations and show consistent HER activity.

  3. The Statistical Evolution of Multiple Generations of Oxidation Products in the Photochemical Aging of Chemically Reduced Organic Aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Kevin R.; Smith, Jared D.; Kessler, Sean; Kroll, Jesse H.

    2011-10-03

    The heterogeneous reaction of hydroxyl radicals (OH) with squalane and bis(2-ethylhexyl) sebacate (BES) particles are used as model systems to examine how distributions of reactionproducts evolve during the oxidation of chemically reduced organic aerosol. A kinetic model of multigenerational chemistry, which is compared to previously measured (squalane) and new(BES) experimental data, reveals that it is the statistical mixtures of different generations of oxidation products that control the average particle mass and elemental composition during thereaction. The model suggests that more highly oxidized reaction products, although initially formed with low probability, play a large role in the production of gas phase reaction products.In general, these results highlight the importance of considering atmospheric oxidation as a statistical process, further suggesting that the underlying distribution of molecules could playimportant roles in aerosol formation as well as in the evolution of key physicochemical properties such as volatility and hygroscopicity.

  4. Helping the Retina Regenerate

    Science.gov (United States)

    ... report summarized two possible therapeutic strategies for RGC regeneration. The first would use stem cells to grow ... recommendations in the report include systematic comparisons of animal models that do and do not regenerate RGCs, ...

  5. An analytic electromagnetic calculation method for performance evolution of doubly fed induction generators for wind turbines

    DEFF Research Database (Denmark)

    Zhang, Wen-juan; Huang, Shou-dao; Chen, Zhe

    2013-01-01

    was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used......An analytic electromagnetic calculation method for doubly fed induction generator (DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed....... The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure...

  6. Illuminating the evolution of equids and rodents with next-generation sequencing of ancient specimens

    DEFF Research Database (Denmark)

    Mouatt, Julia Thidamarth Vilstrup

    The sequencing of ancient DNA provides perspectives on the genetic history of past populations and extinct species. However, ancient DNA research presents specific limitations mostly due to DNA survival, damage and contamination. Yet with stringent laboratory procedures, the sensitivity of target...... enrichment methods and the massive throughput and latest advances within DNA sequencing, the field of ancient DNA has flourished in later years. Those advances have even enabled the sequencing of complete genomes from the past, moving the field into genomic sciences. In this thesis we have used these latest...... developments within ancient DNA research, including target enrichment capture and Next-Generation Sequencing, to address a range of evolutionary questions related to two major mammalian groups, equids and rodents. In particular we have resolved phylogenetic relationships within equids using complete mitochond...

  7. Generation and evolution of internal waves in Banderas Bay, Jalisco-Nayarit, Mexico.

    Science.gov (United States)

    Plata, L. J.; Anatoliy, F.; Iryna, T.; Carlos, V.; Liza, K.; César, M.

    2007-05-01

    The characteristics of internal waves in Banderas Bay (Mexico) were determined by means of data from oceanographical measurements carried on spring and winter during the years 2001 and 2003. The intense fluctuations in the fields of temperature and salinity obtained from a fast oceanographical survey with an undulating CTD on April, 2001, give evidence of the presence and propagation of an internal waves' field. With the help of a bathymetric chart elaborated from a survey carried on in March and May, 2002, we found that the submarine canyon close to the southern coast of the bay, from Cabo Corrientes to Mismaloya, acts like a filter that reflects the diurnal internal tide and allows only the entrance of semidiurnal internal tide. The results of a special experiment measuring the spatiotemporal parameters of internal waves on the wide continental shelf of northwestern Banderas Bay are discussed. The oceanographical measurements consisted of: a) a fast survey with an undulating CTD along a transect perpendicular to the coast, (b) the towing of an array of temperature and depth sensors several times over the continental shelf along transects perpendicular to the coast, and (c) time series of velocity components registered by an acoustic Doppler current profiler placed on the seabed of the bay at 28 m depth. The presence of internal waves generated by semidiurnal tide and corresponding to the second normal oscillation mode (according to the linear theory of internal waves) was determined. Analysis of the data showed that, in the study area, the internal waves generated over the continental slope by the barotropic tide have the shape of an oscillatory bore, which quickly disintegrates during their propagation shoreward, producing short nonlinear waves that dissipate close to the coast, and intense vertical mixing of the whole water column. The interpretation of the results was based on the linear and nonlinear (Korteweg-de Vries equation) theories of internal waves.

  8. Evolution of the collective radiation dose of nuclear reactors from the 2nd through to the 3rd generation and 4th generation sodium-cooled fast reactors

    Science.gov (United States)

    Guidez, Joel; Saturnin, Anne

    2017-11-01

    During the operation of a nuclear reactor, the external individual doses received by the personnel are measured and recorded, in conformity with the regulations in force. The sum of these measurements enables an evaluation of the annual collective dose expressed in man·Sv/year. This information is a useful tool when comparing the different design types and reactors. This article discusses the evolution of the collective dose for several types of reactors, mainly based on publications from the NEA and the IAEA. The spread of good practices (optimization of working conditions and of the organization, sharing of lessons learned, etc.) and ongoing improvements in reactor design have meant that over time, the doses of various origins received by the personnel have decreased. In the case of sodium-cooled fast reactors (SFRs), the compilation and summarizing of various documentary resources has enabled them to be situated and compared to other types of reactors of the second and third generations (respectively pressurized water reactors in operation and EPR under construction). From these results, it can be seen that the doses received during the operation of SFR are significantly lower for this type of reactor.

  9. Temporal evolution of the sulphur oxides emissions from the Greek electricity generation sector.

    Science.gov (United States)

    Kaldellis, J K; Voutsinas, M; Paliatsos, A G; Koronakis, P S

    2004-12-01

    The Greek electricity production sector is based--as far back as the early 60s--on the usage of local lignite and imported heavy-oil. Hence the electricity production process is assumed responsible for a significant contribution to air pollution, including 80% of the national sulphur dioxide emissions. In this context, an extensive and thorough analysis is carried out concerning the SO2 effluents coming from the electricity generation sector during the 1995-2002 period. For this purpose, the available long-term official measurements are taken into consideration and analysed in depth. According to this analysis, the SO2 emissions factor ratio between Southern Greece and Northern Greece lignite fired stations is in the order of 25:1. Additionally, one may definitely state that there is a considerable surcharge of sulphur oxides released by the Greek electricity production system, which although showing a fairly decreasing tendency, is still above the 8.5gr kWh(-1) consumed. Finally, the positive contribution of the natural gas, gradually replacing other fuels, and the operation of a new desulphurisation unit in S. Greece are clearly counterbalanced by the significant and constant annual electricity consumption amplification of the last decade.

  10. Evolution of a Reconfigurable Processing Platform for a Next Generation Space Software Defined Radio

    Science.gov (United States)

    Kacpura, Thomas J.; Downey, Joseph A.; Anderson, Keffery R.; Baldwin, Keith

    2014-01-01

    The National Aeronautics and Space Administration (NASA)Harris Ka-Band Software Defined Radio (SDR) is the first, fully reprogrammable space-qualified SDR operating in the Ka-Band frequency range. Providing exceptionally higher data communication rates than previously possible, this SDR offers in-orbit reconfiguration, multi-waveform operation, and fast deployment due to its highly modular hardware and software architecture. Currently in operation on the International Space Station (ISS), this new paradigm of reconfigurable technology is enabling experimenters to investigate navigation and networking in the space environment.The modular SDR and the NASA developed Space Telecommunications Radio System (STRS) architecture standard are the basis for Harris reusable, digital signal processing space platform trademarked as AppSTAR. As a result, two new space radio products are a synthetic aperture radar payload and an Automatic Detection Surveillance Broadcast (ADS-B) receiver. In addition, Harris is currently developing many new products similar to the Ka-Band software defined radio for other applications. For NASAs next generation flight Ka-Band radio development, leveraging these advancements could lead to a more robust and more capable software defined radio.The space environment has special considerations different from terrestrial applications that must be considered for any system operated in space. Each space mission has unique requirements that can make these systems unique. These unique requirements can make products that are expensive and limited in reuse. Space systems put a premium on size, weight and power. A key trade is the amount of reconfigurability in a space system. The more reconfigurable the hardware platform, the easier it is to adapt to the platform to the next mission, and this reduces the amount of non-recurring engineering costs. However, the more reconfigurable platforms often use more spacecraft resources. Software has similar considerations

  11. Regeneration of periodontal tissues: guided tissue regeneration.

    Science.gov (United States)

    Villar, Cristina C; Cochran, David L

    2010-01-01

    The concept that only fibroblasts from the periodontal ligament or undifferentiated mesenchymal cells have the potential to re-create the original periodontal attachment has been long recognized. Based on this concept, guided tissue regeneration has been applied with variable success to regenerate periodontal defects. Quantitative analysis of clinical outcomes after guided tissue regeneration suggests that this therapy is a successful and predictable procedure to treat narrow intrabony defects and class II mandibular furcations, but offers limited benefits in the treatment of other types of periodontal defects.

  12. Microstructural Evolution and Creep-Rupture Behavior of Fusion Welds Involving Alloys for Advanced Ultrasupercritical Power Generation

    Science.gov (United States)

    Bechetti, Daniel H., Jr.

    Projections for large increases in the global demand for electric power produced by the burning of fossil fuels, in combination with growing environmental concerns surrounding these fuel sources, have sparked initiatives in the United States, Europe, and Asia aimed at developing a new generation of coal fired power plant, termed Advanced Ultrasupercritical (A-USC). These plants are slated to operate at higher steam temperatures and pressures than current generation plants, and in so doing will offer increased process cycle efficiency and reduced greenhouse gas emissions. Several gamma' precipitation strengthened Ni-based superalloys have been identified as candidates for the hottest sections of these plants, but the microstructural instability and poor creep behavior (compared to wrought products) of fusion welds involving these alloys present significant hurdles to their implementation and a gap in knowledge that must be addressed. In this work, creep testing and in-depth microstructural characterization have been used to provide insight into the long-term performance of these alloys. First, an investigation of the weld metal microstructural evolution as it relates to creep strength reductions in A-USC alloys INCONELRTM 740, NIMONICRTM 263 (INCONEL and NIMONIC are registered trademarks of Special Metals Corporation), and HaynesRTM 282RTM (Haynes and 282 are registered trademarks of Haynes International) was performed. gamma'-precipitate free zones were identified in two of these three alloys, and their development was linked to the evolution of phases that precipitate at the expense of gamma'. Alloy 282 was shown to avoid precipitate free zone formation because the precipitates that form during long term aging in this alloy are poor in the gamma'-forming elements. Next, the microstructural evolution of INCONELRTM 740H (a compositional variant of alloy 740) during creep was investigated. Gleeble-based interrupted creep and creep-rupture testing was used to

  13. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators.

    Science.gov (United States)

    Manonmani, N; Subbiah, V; Sivakumar, L

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  14. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators

    Directory of Open Access Journals (Sweden)

    N. Manonmani

    2015-01-01

    Full Text Available The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs. The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation.

  15. Evolution of robust circadian clocks in Drosophila melanogaster populations reared in constant dark for over 330 generations

    Science.gov (United States)

    Shindey, Radhika; Varma, Vishwanath; Nikhil, K. L.; Sharma, Vijay Kumar

    2016-10-01

    Robustness is considered to be an important feature of biological systems which may evolve when the functionality of a trait is associated with higher fitness across multiple environmental conditions. Thus, the ability to maintain stable biological phenotypes across environments is thought to be of adaptive value. Previously, we have reported higher intrinsic activity levels (activity levels of free-running rhythm in constant darkness) and power of rhythm (as assessed by amplitude of the periodogram) in Drosophila melanogaster populations (stocks) reared in constant darkness (DD stocks) as compared to those reared in constant light (LL stocks) and 12:12-h light-dark cycles (LD stocks) for over 19 years (˜330 generations). In the current study, we intended to examine whether the enhanced levels of activity observed in DD stocks persist under various environments such as photoperiods, ambient temperatures, non-24-h light-dark (LD) cycles, and semi-natural conditions (SN). We found that DD stocks largely retain their phenotype of enhanced activity levels across most of the above-mentioned environments suggesting the evolution of robust circadian clocks in DD stocks. Furthermore, we compared the peak activity levels of the three stocks across different environmental conditions relative to their peaks in constant darkness and found that the change in peak activity levels upon entrainment was not significantly different across the three stocks for any of the examined environmental conditions. This suggests that the enhancement of activity levels in DD stocks is not due to differential sensitivity to environment. Thus, these results suggest that rearing in constant darkness (DD) leads to evolution of robust circadian clocks suggesting a possible adaptive value of possessing such rhythms under constant dark environments.

  16. Differential Evolution Based IDWNN Controller for Fault Ride-Through of Grid-Connected Doubly Fed Induction Wind Generators

    Science.gov (United States)

    Manonmani, N.; Subbiah, V.; Sivakumar, L.

    2015-01-01

    The key objective of wind turbine development is to ensure that output power is continuously increased. It is authenticated that wind turbines (WTs) supply the necessary reactive power to the grid at the time of fault and after fault to aid the flowing grid voltage. At this juncture, this paper introduces a novel heuristic based controller module employing differential evolution and neural network architecture to improve the low-voltage ride-through rate of grid-connected wind turbines, which are connected along with doubly fed induction generators (DFIGs). The traditional crowbar-based systems were basically applied to secure the rotor-side converter during the occurrence of grid faults. This traditional controller is found not to satisfy the desired requirement, since DFIG during the connection of crowbar acts like a squirrel cage module and absorbs the reactive power from the grid. This limitation is taken care of in this paper by introducing heuristic controllers that remove the usage of crowbar and ensure that wind turbines supply necessary reactive power to the grid during faults. The controller is designed in this paper to enhance the DFIG converter during the grid fault and this controller takes care of the ride-through fault without employing any other hardware modules. The paper introduces a double wavelet neural network controller which is appropriately tuned employing differential evolution. To validate the proposed controller module, a case study of wind farm with 1.5 MW wind turbines connected to a 25 kV distribution system exporting power to a 120 kV grid through a 30 km 25 kV feeder is carried out by simulation. PMID:26516636

  17. Seasonal evolution of net and regenerated silica production around a natural Fe-fertilized area in the Southern Ocean estimated with Si isotopic approaches

    Science.gov (United States)

    Closset, I.; Lasbleiz, M.; Leblanc, K.; Quéguiner, B.; Cavagna, A.-J.; Elskens, M.; Navez, J.; Cardinal, D.

    2014-10-01

    A massive diatom bloom is observed each year in the surface waters of the naturally Fe-fertilized Kerguelen Plateau (Southern Ocean). We measured biogenic silica production and dissolution fluxes (ρSi and ρDiss, respectively) in the mixed layer in the vicinity of the Kerguelen Plateau during austral spring 2011 (KEOPS-2 cruise). We compare results from a high-nutrient low-chlorophyll reference station and stations with different degrees of iron enrichment and bloom conditions. Above the plateau biogenic ρSi are among the highest reported so far in the Southern Ocean (up to 47.9 mmol m-2 d-1). Although significant (10.2 mmol m-2 d-1 on average), ρDiss were generally much lower than production rates. Uptake ratios (ρSi : ρC and ρSi : ρN) confirm that diatoms strongly dominate primary production in this area. At the bloom onset, decreasing dissolution-to-production ratios (D : P) indicate that the remineralization of silica could sustain most of the low silicon uptake and that the system progressively shifts toward a silica production regime which must be mainly supported by new source of silicic acid. Moreover, by comparing results from the two KEOPS expeditions (spring 2011 and summer 2005), we suggest that there is a seasonal evolution of the processes decoupling Si and N cycles in the area. Indeed, the consumption of H4SiO4 standing stocks occurs only during the growing stage of the bloom when strong net silica production is observed, contributing to higher H4SiO4 depletion relative to NO3-. Then, the decoupling of H4SiO4 and NO3- is mainly controlled by the more efficient nitrogen recycling relative to Si. Gross Si : N uptake ratios were higher in the Fe-rich regions compared to the high-nutrient low-chlorophyll (HNLC) area, likely due to different diatom communities. This suggests that the diatom responses to natural Fe fertilization are more complex than previously thought, and that natural iron fertilization over long timescales does not necessarily

  18. Seasonal evolution of net and regenerated silica production around a natural Fe-fertilized area in the Southern Ocean estimated from Si isotopic approaches

    Science.gov (United States)

    Closset, I.; Lasbleiz, M.; Leblanc, K.; Quéguiner, B.; Cavagna, A.-J.; Elskens, M.; Navez, J.; Cardinal, D.

    2014-05-01

    A massive diatom-bloom is observed each year in the surface waters of the naturally Fe fertilized Kerguelen Plateau (Southern Ocean). We measured biogenic silica production and dissolution fluxes in the mixed layer in the vicinity of the Kerguelen Plateau during austral spring 2011 (KEOPS-2 cruise). We compare results from a High-Nutrient Low-Chlorophyll reference station and stations with different degrees of iron enrichment and bloom conditions. Above the Plateau biogenic silica production fluxes are among the highest reported so far in the Southern Ocean (up to 47.9 mmol m-2 d-1). Although significant (10.2 mmol m-2 d-1 in average), silica dissolution rates were generally much lower than production rates. Uptake ratios (Si:C and Si:N) confirm that diatoms strongly dominate the primary production in this area. At the bloom onset, decreasing dissolution to production ratios (D:P) indicate that the remineralization of silica could sustained most of the low silicon uptake and that the system progressively shifts toward a silica production regime which must be mainly supported by new source of silicic acid. Moreover, by comparing results from the two KEOPS-expeditions (spring 2011 and summer 2005), we suggest that there is a seasonal evolution on the processes decoupling Si and N cycles in the area. Indeed, the consumption of H4SiO4 standing stocks occurs only during the growing stage of the bloom when strong net silica production is observed, contributing to a higher H4SiO4 depletion relative to NO3-. Then, the decoupling between H4SiO4 and NO3- is mainly controlled by the more efficient nitrogen recycling relative to Si. Gross-Si:N uptake ratios were higher in the Fe-rich regions compared to the HNLC area, likely due to different diatoms communities. This suggests that the diatom responses to natural Fe fertilization are more complex than previously thought, and that natural iron fertilization over long time scales does not necessarily decrease Si:N uptake ratios

  19. Reduce, reuse, recycle - Developmental signals in spinal cord regeneration.

    Science.gov (United States)

    Cardozo, Marcos Julian; Mysiak, Karolina S; Becker, Thomas; Becker, Catherina G

    2017-12-01

    Anamniotes, fishes and amphibians, have the capacity to regenerate spinal cord tissue after injury, generating new neurons that mature and integrate into the spinal circuitry. Elucidating the molecular signals that promote this regeneration is a fundamental question in regeneration research. Model systems, such as salamanders and larval and adult zebrafish are used to analyse successful regeneration. This shows that many developmental signals, such as Notch, Hedgehog (Hh), Bone Morphogenetic Protein (BMP), Wnt, Fibroblast Growth Factor (FGF), Retinoic Acid (RA) and neurotransmitters are redeployed during regeneration and activate resident spinal progenitor cells. Here we compare the roles of these signals in spinal cord development and regeneration of the much larger and fully patterned adult spinal cord. Understanding how developmental signalling systems are reactivated in successfully regenerating species may ultimately lead to ways to reactivate similar systems in mammalian progenitor cells, which do not show neurogenesis after spinal injury. Copyright © 2017. Published by Elsevier Inc.

  20. Muscle Cells Provide Instructions for Planarian Regeneration

    Directory of Open Access Journals (Sweden)

    Jessica N. Witchley

    2013-08-01

    Full Text Available Regeneration requires both potential and instructions for tissue replacement. In planarians, pluripotent stem cells have the potential to produce all new tissue. The identities of the cells that provide regeneration instructions are unknown. Here, we report that position control genes (PCGs that control regeneration and tissue turnover are expressed in a subepidermal layer of nonneoblast cells. These subepidermal cells coexpress many PCGs. We propose that these subepidermal cells provide a system of body coordinates and positional information for regeneration, and identify them to be muscle cells of the planarian body wall. Almost all planarian muscle cells express PCGs, suggesting a dual function: contraction and control of patterning. PCG expression is dynamic in muscle cells after injury, even in the absence of neoblasts, suggesting that muscle is instructive for regeneration. We conclude that planarian regeneration involves two highly flexible systems: pluripotent neoblasts that can generate any new cell type and muscle cells that provide positional instructions for the regeneration of any body region.

  1. Muscle cells provide instructions for planarian regeneration.

    Science.gov (United States)

    Witchley, Jessica N; Mayer, Mirjam; Wagner, Daniel E; Owen, Jared H; Reddien, Peter W

    2013-08-29

    Regeneration requires both potential and instructions for tissue replacement. In planarians, pluripotent stem cells have the potential to produce all new tissue. The identities of the cells that provide regeneration instructions are unknown. Here, we report that position control genes (PCGs) that control regeneration and tissue turnover are expressed in a subepidermal layer of nonneoblast cells. These subepidermal cells coexpress many PCGs. We propose that these subepidermal cells provide a system of body coordinates and positional information for regeneration, and identify them to be muscle cells of the planarian body wall. Almost all planarian muscle cells express PCGs, suggesting a dual function: contraction and control of patterning. PCG expression is dynamic in muscle cells after injury, even in the absence of neoblasts, suggesting that muscle is instructive for regeneration. We conclude that planarian regeneration involves two highly flexible systems: pluripotent neoblasts that can generate any new cell type and muscle cells that provide positional instructions for the regeneration of any body region. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  2. The microstructural evolution and elemental distribution of a 3rd generation 1 GPa advanced high strength steel during double pulse resistance spot welding

    NARCIS (Netherlands)

    Eftekharimilani, P.; van der Aa, EM; Hermans, M.J.M.; Richardson, I.M.

    2017-01-01

    This paper presents the effects of double pulse resistance spot welding (RSW) on the microstructural evolution, elemental distribution and mechanical properties of a 3rd generation 1 GPa advanced high strength steel (AHSS). In order to investigate the effect of double pulsing, the steel was exposed

  3. Evolution-based strategy to generate non-genetically modified organisms Saccharomyces cerevisiae strains impaired in sulfate assimilation pathway.

    Science.gov (United States)

    De Vero, L; Solieri, L; Giudici, P

    2011-11-01

    An evolution-based strategy was designed to screen novel yeast strains impaired in sulfate assimilation. Specifically, molybdate and chromate resistance was used as selectable phenotype to select sulfate permease-deficient variants that unable to produce sulfites and hydrogen sulfide (H(2) S). Four Saccharomyces cerevisiae parent strains were induced to sporulate. After tetrad digestion, spore suspensions were observed under the microscope to monitor the conjugation of gametes. Then, the cell suspension was inoculated in tubes containing YPD medium supplemented with ammonium molybdate or potassium chromate. Forty-four resistant strains were obtained and then tested in microvinifications. Three strains with a low sulfite production (SO2 < 10 mg l(-1)) and with an impaired H2S production in grape must without added sulfites were selected. Our strategy enabled the selection of improved yeasts with desired oenological characteristics. Particularly, resistance to toxic analogues of sulfate allowed us to detect strains that unable to assimilate sulfates. This strategy that combines the sexual recombination of spores and application of a specific selective pressure provides a rapid screening method to generate genetic variants and select improved wine yeast strains with an impaired metabolism regarding the production of sulfites and H2S. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

  4. Genome evolution is driven by gene expression-generated biophysical constraints through RNA-directed genetic variation: A hypothesis.

    Science.gov (United States)

    Auboeuf, Didier

    2017-10-01

    The biogenesis of RNAs and proteins is a threat to the cell. Indeed, the act of transcription and nascent RNAs challenge DNA stability. Both RNAs and nascent proteins can also initiate the formation of toxic aggregates because of their physicochemical properties. In reviewing the literature, I show that co-transcriptional and co-translational biophysical constraints can trigger DNA instability that in turn increases the likelihood that sequences that alleviate the constraints emerge over evolutionary time. These directed genetic variations rely on the biogenesis of small RNAs that are transcribed directly from challenged DNA regions or processed from the transcripts that directly or indirectly generate constraints or aggregates. These small RNAs can then target the genomic regions from which they initially originate and increase the local mutation rate of the targeted loci. This mechanism is based on molecular pathways involved in anti-parasite genome defence systems, and implies that gene expression-related biophysical constraints represent a driving force of genome evolution. © 2017 The Authors. BioEssays Published by Wiley Periodicals, Inc.

  5. Complex evolution of the electronic structure from polycrystalline to monocrystalline graphene: generation of a new Dirac point

    Science.gov (United States)

    Nunes, Ricardo; Araújo, Joice

    2010-03-01

    First calculations, employed to address the properties of polycrystalline graphene, indicate that the electronic structure of tilt grain boundaries in this system [1-4] displays a rather complex evolution towards graphene bulk, as the tilt angle decreases, with the generation of a new Dirac point at the Fermi level, and an anisotropic Dirac cone of low energy excitations. Moreover, the usual Dirac point at the K point falls below the Fermi level, and rises towards it as the tilt angle decreases. Further, our calculations indicate that the grain-boundary formation energy behaves non-monotonically with the tilt angle, due to a change in the the spatial distribution and relative contributions of the bond-stretching and bond-bending deformations associated with the formation of the defect.[4pt] [1] L. B. Biedermann et al., Phys. Rev. B 79, 125411 (2009). [0pt] [2] S. S. Datta et al., Nanoletters 9, 7 (2009). [0pt] [3] P. Simonis et al., Surf. Sci. 511, 319 (2002). [0pt] [4] G. Gu et al., Appl. Phys. Lett. 90, 253507 (2007).

  6. Desulfurization sorbent regeneration

    Science.gov (United States)

    Jalan, V.M.; Frost, D.G.

    1982-07-07

    A spent solid sorbent resulting from the removal of hydrogen sulfide from a fuel gas flow is regenerated with a steam-air mixture. The mixture of steam and air may also include additional nitrogen or carbon dioxide. The gas mixture contacts the spent sorbent containing metal sulfide at a temperature above 500/sup 0/C to regenerate the sulfide to metal oxide or carbonate. Various metal species including the period four transition metals and the lanthanides are suitable sorbents that may be regenerated by this method. In addition, the introduction of carbon dioxide gas permits carbonates such as those of strontium, barium and calcium to be regenerated. The steam permits regeneration of spent sorbent without formation of metal sulfate. Moreover, the regeneration will proceed with low oxygen concentrations and will occur without the increase in temperature to minimize the risk of sintering and densification of the sorbent. This method may be used for high-temperature fuel cells.

  7. Regeneration in Swimming

    OpenAIRE

    Lehocký, Jan

    2006-01-01

    Topic: Regeneration in the swimming Aim: Using a questionnaire to find out information and views on the need of regeneration and its use. Process the results and evaluate the survey data into synoptic tables and graphs. Giving a comprehensive overview of the field of regeneration in the swimming sport. Method: The research group of our work happened 30 swimmers - participants Championship Czech Republic 2005 in short swimming pool at the age of 15-33 years. Results: It was confirmed that most...

  8. Collecting, rearing, spawning and inducing regeneration of the starlet sea anemone, Nematostella vectensis.

    Science.gov (United States)

    Stefanik, Derek J; Friedman, Lauren E; Finnerty, John R

    2013-05-01

    Over the past 20 years, the starlet sea anemone, Nematostella vectensis, a small estuarine animal, has emerged as a powerful model system for field and laboratory studies of development, evolution, genomics, molecular biology and toxicology. Here we describe how to collect Nematostella, culture it through its entire sexual life cycle and induce regeneration for the production of clonal stocks. In less than 1 h at a suitable field site, a researcher on foot can collect hundreds of individual anemones. In a few months, it is possible to establish a laboratory colony that will be reliable in generating hundreds or thousands of fertilized eggs on a roughly weekly schedule. By inducing regeneration roughly every 2 weeks, in less than 6 months, one can establish a clonal stock consisting of hundreds of genetically identical anemones. These results can be achieved very inexpensively and without specialized equipment.

  9. Composite Matrix Regenerator for Stirling Engines

    Science.gov (United States)

    Knowles, Timothy R.

    1997-01-01

    This project concerns the design, fabrication and testing of carbon regenerators for use in Stirling power convertors. Radial fiber design with nonmetallic components offers a number of potential advantages over conventional steel regenerators: reduced conduction and pressure drop losses, and the capability for higher temperature, higher frequency operation. Diverse composite fabrication methods are explored and lessons learned are summarized. A pulsed single-blow test rig has been developed that has been used for generating thermal effectiveness data for different flow velocities. Carbon regenerators have been fabricated by carbon vapor infiltration of electroflocked preforms. Performance data in a small Stirling engine are obtained. Prototype regenerators designed for the BP-1000 power convertor were fabricated and delivered to NASA-Lewis.

  10. Gradients in Planarian Regeneration and Homeostasis

    Science.gov (United States)

    Adell, Teresa; Cebrià, Francesc; Saló, Emili

    2010-01-01

    Planarian regeneration was one of the first models in which the gradient concept was developed. Morphological studies based on the analysis of the regeneration rates of planarian fragments from different body regions, the generation of heteromorphoses, and experiments of tissue transplantation led T.H. Morgan (1901) and C.M Child (1911) to postulate different kinds of gradients responsible for the regenerative process in these highly plastic animals. However, after a century of research, the role of morphogens in planarian regeneration has yet to be demonstrated. This may change soon, as the sequencing of the planarian genome and the possibility of performing gene functional analysis by RNA interference (RNAi) have led to the isolation of elements of the bone morphogenetic protein (BMP), Wnt, and fibroblast growth factor (FGF) pathways that control patterning and axial polarity during planarian regeneration and homeostasis. Here, we discuss whether the actions of these molecules could be based on morphogenetic gradients. PMID:20182600

  11. Optic nerve regeneration.

    Science.gov (United States)

    Benowitz, Larry I; Yin, Yuqin

    2010-08-01

    Retinal ganglion cells are usually not able to regenerate their axons after optic nerve injury or degenerative disorders, resulting in lifelong visual loss. This situation can be partially reversed by activating the intrinsic growth state of retinal ganglion cells, maintaining their viability, and counteracting inhibitory signals in the extracellular environment. Advances during the past few years continue to extend the amount of regeneration that can be achieved in animal models. These findings give hope that clinically meaningful regeneration may become a reality within a few years if regenerating axons can be guided to their appropriate destinations.

  12. Functional Tooth Regeneration.

    Science.gov (United States)

    Oshima, Masamitsu; Ogawa, Miho; Tsuji, Takashi

    2017-01-01

    Three-dimensional organogenesis in vivo is principally regulated by the spatiotemporal developmental process that relies on the cellular behavior such as cell growth, migration, differentiation, and cell-to-cell interaction. Organ development and morphogenesis have been elucidated to be regulated by the proper transient expression of various signaling molecules including cytokines, extracellular matrix, and adhesion molecules based on the epithelial and mesenchymal interactions. Current bioengineering technology for regenerating three-dimensional organ has progressed to the replication of organogenesis, thereby enabling the development of fully functional bioengineered organs using bioengineered organ germs that are generated from immature stem cells via tissue engineering technology in vitro.To achieve precise replication of organogenesis, we have developed a novel three-dimensional cell manipulation method designated the organ germ method, and enabled the generation of a structurally correct and fully functional bioengineered tooth in vivo. This method is also expected to be utilized for analyzing gene and protein functions during organogenesis. Here, we describe protocols for the tooth germ reconstitution by using the organ germ method and for the functional analysis of tooth development in vitro and in vivo.

  13. Marine bacteria in deep Arctic and Antarctic ice cores: a proxy for evolution in oceans over 300 million generations

    Directory of Open Access Journals (Sweden)

    P. B. Price

    2012-10-01

    Full Text Available Using fluorescence spectrometry to map autofluorescence of chlorophyll (Chl and tryptophan (Trp versus depth in polar ice cores in the US National Ice Core Laboratory, we found that the Chl and Trp concentrations often showed an annual modulation of up to 25%, with peaks at depths corresponding to local summers. Using epifluorescence microscopy (EFM and flow cytometry (FCM triggered on red fluorescence at 670 nm to study microbes from unstained melts of the polar ice, we inferred that picocyanobacteria may have been responsible for the red fluorescence in the cores. Micron-size bacteria in all ice melts from Arctic and Antarctic sites showed FCM patterns of scattering and of red vs. orange fluorescence (interpreted as due to Chl vs. phycoerythrin (PE that bore similarities to patterns of cultures of unstained picocyanobacteria Prochlorococcus and Synechococcus. Concentrations in ice from all sites were low, but measurable at ~ 1 to ~ 103 cells cm−3. Calibrations showed that FCM patterns of mineral grains and volcanic ash could be distinguished from microbes with high efficiency by triggering on scattering instead of by red fluorescence. Average Chl and PE autofluorescence intensities showed no decrease per cell with time during up to 150 000 yr of storage in glacial ice. Taking into account the annual modulation of ~ 25% and seasonal changes of ocean temperatures and winds, we suggest that picocyanobacteria are wind-transported year-round from warmer ocean waters onto polar ice. Ice cores offer the opportunity to study evolution of marine microbes over ~ 300 million generations by analysing their genomes vs. depth in glacial ice over the last 700 000 yr as frozen proxies for changes in their genomes in oceans.

  14. Hyaluronic acid in the tail and limb of amphibians and lizards recreates permissive embryonic conditions for regeneration due to its hygroscopic and immunosuppressive properties.

    Science.gov (United States)

    Alibardi, Lorenzo

    2017-12-01

    The present review focuses on the role of hyaluronate (hyaluronic acid; HA) during limb and tail regeneration in amphibians and lizards mainly in relation to cells of the immune system. This non-sulfated glycosaminoglycan (GAG) increases in early stages of wound healing and blastema formation, like during limb or tail embryogenesis, when the immune system is still immature. The formation of a regenerating blastema occurs by the accumulation of mesenchymal cells displaying embryonic-like antigens and HA. This GAG adsorbs large amount of water and generates a soft tissue over 80% hydrated where mesenchymal and epithelial cells can move and interact, an obligatory passage for organ regeneration. GAGs and HA in particular rise to a high amount and coat plasma membranes of blastema cells forming a shield that likely impedes to the circulating immune cells to elicit an immune reaction against the embryonic-like antigens present on blastema cells. The evolution of limb-tail regeneration in amphibians dates back to the Devonian-Carboniferous, while tail regeneration in lizards is a more recent evolution process, possibly occurred since the Jurassic, which is unique among amniotes. Both processes are associated with the reactivation of proliferating embryonic programs that involve the upregulation of genes for Wnt, non-coding RNAs, and HA synthesis in an immune-suppress organ, the regenerative blastema. Failure of maintaining a lasting HA synthesis for the formation of a highly hydrated blastema leads to scarring, the common healing process of amniotes equipped with an efficient immune system. The study of amphibian and lizard regeneration indicates that attempts to stimulate organ regeneration in other vertebrates require the induction of a highly hydrated and immune-depressed, HA-rich environment, similar to the extracellular environment present during development. © 2017 Wiley Periodicals, Inc.

  15. Nicotinamide adenine dinucleotide biosynthesis promotes liver regeneration.

    Science.gov (United States)

    Mukherjee, Sarmistha; Chellappa, Karthikeyani; Moffitt, Andrea; Ndungu, Joan; Dellinger, Ryan W; Davis, James G; Agarwal, Beamon; Baur, Joseph A

    2017-02-01

    The regenerative capacity of the liver is essential for recovery from surgical resection or injuries induced by trauma or toxins. During liver regeneration, the concentration of nicotinamide adenine dinucleotide (NAD) falls, at least in part due to metabolic competition for precursors. To test whether NAD availability restricts the rate of liver regeneration, we supplied nicotinamide riboside (NR), an NAD precursor, in the drinking water of mice subjected to partial hepatectomy. NR increased DNA synthesis, mitotic index, and mass restoration in the regenerating livers. Intriguingly, NR also ameliorated the steatosis that normally accompanies liver regeneration. To distinguish the role of hepatocyte NAD levels from any systemic effects of NR, we generated mice overexpressing nicotinamide phosphoribosyltransferase, a rate-limiting enzyme for NAD synthesis, specifically in the liver. Nicotinamide phosphoribosyltransferase overexpressing mice were mildly hyperglycemic at baseline and, similar to mice treated with NR, exhibited enhanced liver regeneration and reduced steatosis following partial hepatectomy. Conversely, mice lacking nicotinamide phosphoribosyltransferase in hepatocytes exhibited impaired regenerative capacity that was completely rescued by administering NR. NAD availability is limiting during liver regeneration, and supplementation with precursors such as NR may be therapeutic in settings of acute liver injury. (Hepatology 2017;65:616-630). © 2016 by the American Association for the Study of Liver Diseases.

  16. Tooth regeneration: Current status

    Directory of Open Access Journals (Sweden)

    Dadu Shifali

    2009-01-01

    Full Text Available Regeneration of a functional tooth has the potential to be a promising therapeutic strategy. Experiments have shown that with the use of principles of bioengineering along with adult stem cells, scaffold material, and signaling molecules, tooth regeneration is possible. Research work is in progress on creating a viable bioroot with all its support. A new culture needs to be created that can possibly provide all the nutrients to the stem cells. With the ongoing research, tissue engineering is likely to revolutionize dental health and well-being of people by regenerating teeth over the next decade.

  17. Tooth regeneration: current status.

    Science.gov (United States)

    Dadu, Shifali S

    2009-01-01

    Regeneration of a functional tooth has the potential to be a promising therapeutic strategy. Experiments have shown that with the use of principles of bioengineering along with adult stem cells, scaffold material, and signaling molecules, tooth regeneration is possible. Research work is in progress on creating a viable bioroot with all its support. A new culture needs to be created that can possibly provide all the nutrients to the stem cells. With the ongoing research, tissue engineering is likely to revolutionize dental health and well-being of people by regenerating teeth over the next decade.

  18. [Regeneration of planarians: experimental object].

    Science.gov (United States)

    Sheĭman, I M; Kreshchenko, I D

    2015-01-01

    We discuss the expediency of using invertebrates, such as flatworms and planarians, as experimental objects. Free-living planarian flatworms (phylum Platyhelminthes, class Turbellaria) are invertebrate animals in which a bilateral symmetry appears for the first time in evolution and organs and tissues form. As the highest ecological link of the food chain--predators--these animals are characterized by a set of behavioral reactions controlled by a differentiated central nervous system. Planarians have unsurpassed ability to regenerate lost or damaged body parts. Owing to the ease of their breeding and their convenience for manipulations, these animals are used to study the influence of chemical and physical factors on the processes of life, growth, and reproduction. Currently, planarians are recognized as a model for biological research in the field of regeneration, stem cell biology, study of their proliferation and differentiation, as well as the regulatory mechanisms of morphogenetic processes. The genome of the planarian Schmidtea mediterranea was fully sequenced, which opened up the opportunity to work with this object at the molecular biological level. Furthermore, planarians are used in neurobiological and toxicological studies, in studying the evolutionary aspects of centralization of the nervous system, mechanisms of muscle contraction, and in the development of new antiparasitic drugs. This review aims to demonstrate the relevance and diversity of research conducted on simple biological objects--planarians--to awider audience to show the historical continuity of these studies and their wide geographical distribution and to focus on the studies carried out in Russia, which, as a rule, are not included in the foreign reviews on planarian regeneration.

  19. Success and complication rates of lead extraction with the first- vs. the second-generation Evolution mechanical sheath.

    Science.gov (United States)

    Witte, Olivier A; Adiyaman, Ahmet; Smit, Jaap Jan J; Ramdat Misier, Anand R; Elvan, Arif; Ghani, Abdul; Delnoy, Peter Paul H M

    2017-10-01

    The Evolution sheath (Cook Medical, USA) is a power sheath frequently used for chronic lead extraction. In 2013, a novel type (bidirectional) of Evolution sheath (the RL type) was introduced. We evaluated differences in success and complication rates of the two types. From 2009 to 2015, all lead extractions requiring the use of an Evolution sheath were prospectively examined. According to the current guidelines, complete procedural success was defined as the removal of all targeted lead materials. Clinical success was the retention of a small portion of the lead, and failure was the inability to achieve either complete procedural or clinical success or the development of any permanently disabling complication. The Evolution sheath was used to extract 149 leads in 103 patients. The first 56 leads were extracted with the original unidirectional sheath, and 93 leads were extracted with the novel bidirectional R/L type. The median age of the lead at the time of extraction was 6.8 vs. 9.1 years (P = 0.007). Complete procedural success was higher for the Evolution R/L (80.0 vs. 98%, P = 0.0004). Clinical success rate was 98 vs. 99%. There were no major complications and 6 (12.0%) vs. 2 (3.8%) minor complications (P = 0.153). We did not observe changes in success rates or complications over time, meaning that the difference cannot be explained by learning curve. Use of the novel Evolution R/L sheath vs. the original Evolution sheath was associated with significant higher complete success rates, without major complications and with a trend towards the reduction of minor complications.

  20. Spatially restricted dental regeneration drives pufferfish beak development

    Science.gov (United States)

    Thiery, Alexandre P.; Shono, Takanori; Kurokawa, Daisuke; Britz, Ralf; Johanson, Zerina

    2017-01-01

    Vertebrate dentitions are extraordinarily diverse in both morphology and regenerative capacity. The teleost order Tetraodontiformes exhibits an exceptional array of novel dental morphologies, epitomized by constrained beak-like dentitions in several families, i.e., porcupinefishes, three-toothed pufferfishes, ocean sunfishes, and pufferfishes. Modification of tooth replacement within these groups leads to the progressive accumulation of tooth generations, underlying the structure of their beaks. We focus on the dentition of the pufferfish (Tetraodontidae) because of its distinct dental morphology. This complex dentition develops as a result of (i) a reduction in the number of tooth positions from seven to one per quadrant during the transition from first to second tooth generations and (ii) a dramatic shift in tooth morphogenesis following the development of the first-generation teeth, leading to the elongation of dental units along the jaw. Gene expression and 1,1′-Dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) lineage tracing reveal a putative dental epithelial progenitor niche, suggesting a highly conserved mechanism for tooth regeneration despite the development of a unique dentition. MicroCT analysis reveals restricted labial openings in the beak, through which the dental epithelium (lamina) invades the cavity of the highly mineralized beak. Reduction in the number of replacement tooth positions coincides with the development of only four labial openings in the pufferfish beak, restricting connection of the oral epithelium to the dental cavity. Our data suggest the spatial restriction of dental regeneration, coupled with the unique extension of the replacement dental units throughout the jaw, are primary contributors to the evolution and development of this unique beak-like dentition. PMID:28507130

  1. A Comprehensive Transcriptomic and Proteomic Analysis of Hydra Head Regeneration.

    Science.gov (United States)

    Petersen, Hendrik O; Höger, Stefanie K; Looso, Mario; Lengfeld, Tobias; Kuhn, Anne; Warnken, Uwe; Nishimiya-Fujisawa, Chiemi; Schnölzer, Martina; Krüger, Marcus; Özbek, Suat; Simakov, Oleg; Holstein, Thomas W

    2015-08-01

    The cnidarian freshwater polyp Hydra sp. exhibits an unparalleled regeneration capacity in the animal kingdom. Using an integrative transcriptomic and stable isotope labeling by amino acids in cell culture proteomic/phosphoproteomic approach, we studied stem cell-based regeneration in Hydra polyps. As major contributors to head regeneration, we identified diverse signaling pathways adopted for the regeneration response as well as enriched novel genes. Our global analysis reveals two distinct molecular cascades: an early injury response and a subsequent, signaling driven patterning of the regenerating tissue. A key factor of the initial injury response is a general stabilization of proteins and a net upregulation of transcripts, which is followed by a subsequent activation cascade of signaling molecules including Wnts and transforming growth factor (TGF) beta-related factors. We observed moderate overlap between the factors contributing to proteomic and transcriptomic responses suggesting a decoupled regulation between the transcriptional and translational levels. Our data also indicate that interstitial stem cells and their derivatives (e.g., neurons) have no major role in Hydra head regeneration. Remarkably, we found an enrichment of evolutionarily more recent genes in the early regeneration response, whereas conserved genes are more enriched in the late phase. In addition, genes specific to the early injury response were enriched in transposon insertions. Genetic dynamicity and taxon-specific factors might therefore play a hitherto underestimated role in Hydra regeneration. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  2. Regeneration review reprise

    OpenAIRE

    Whited, Jessica LaMae; Tabin, Clifford James

    2010-01-01

    There have been notable advances in the scientific understanding of regeneration within the past year alone, including two recently published in BMC Biology. Increasingly, progress in the regeneration field is being inspired by comparisons with stem cell biology and enabled by newly developed techniques that allow simultaneous examination of thousands of genes and proteins. See research articles http://www.biomedcentral.com/1741-7007/7/83 and http://www.biomedcentral.com/1741-7007/8/5.

  3. The (re)generation of splenic tissue

    NARCIS (Netherlands)

    Hovius, J. W. R.; Verberne, H. J.; Bennink, R. J.; Blok, W. L.

    2010-01-01

    A 48-year-old man with a history of a traumatic splenic rupture followed by splenectomy at the age of 5 years was referred to the outpatient clinic with markedly elevated liver enzymes. He was diagnosed with alcoholic liver cirrhosis. Ultrasound of the upper abdomen revealed hepatomegaly and

  4. The (re)generation of splenic tissue

    OpenAIRE

    Hovius, J W R; Verberne, H J; Bennink, R J; Blok, W L

    2010-01-01

    A 48-year-old man with a history of a traumatic splenic rupture followed by splenectomy at the age of 5 years was referred to the outpatient clinic with markedly elevated liver enzymes. He was diagnosed with alcoholic liver cirrhosis. Ultrasound of the upper abdomen revealed hepatomegaly and suggested a central mass in the liver. Subsequent MRI of the abdomen did not show a hepatic mass, but revealed multiple intraperitoneal and retroperitoneal ovoid structures with a maximum diameter of 3 cm...

  5. The (re)generation of splenic tissue

    Science.gov (United States)

    Hovius, J W R; Verberne, H J; Bennink, R J; Blok, W L

    2010-01-01

    A 48-year-old man with a history of a traumatic splenic rupture followed by splenectomy at the age of 5 years was referred to the outpatient clinic with markedly elevated liver enzymes. He was diagnosed with alcoholic liver cirrhosis. Ultrasound of the upper abdomen revealed hepatomegaly and suggested a central mass in the liver. Subsequent MRI of the abdomen did not show a hepatic mass, but revealed multiple intraperitoneal and retroperitoneal ovoid structures with a maximum diameter of 3 cm. A peripheral blood smear did not reveal Howell-Jolly bodies suggesting intact splenic function. The diagnosis splenosis—that is, autotransplantation of splenic tissue after iatrogenic/traumatic rupture of the spleen—was considered and confirmed by SPECT-CT with technetium-99m (99mTc) labelled heat-denatured autologous red blood cells. PMID:22778202

  6. Resolving Heart Regeneration by Replacement Histone Profiling.

    Science.gov (United States)

    Goldman, Joseph Aaron; Kuzu, Guray; Lee, Nutishia; Karasik, Jaclyn; Gemberling, Matthew; Foglia, Matthew J; Karra, Ravi; Dickson, Amy L; Sun, Fei; Tolstorukov, Michael Y; Poss, Kenneth D

    2017-02-27

    Chromatin regulation is a principal mechanism governing animal development, yet it is unclear to what extent structural changes in chromatin underlie tissue regeneration. Non-mammalian vertebrates such as zebrafish activate cardiomyocyte (CM) division after tissue damage to regenerate lost heart muscle. Here, we generated transgenic zebrafish expressing a biotinylatable H3.3 histone variant in CMs and derived cell-type-specific profiles of histone replacement. We identified an emerging program of putative enhancers that revise H3.3 occupancy during regeneration, overlaid upon a genome-wide reduction of H3.3 from promoters. In transgenic reporter lines, H3.3-enriched elements directed gene expression in subpopulations of CMs. Other elements increased H3.3 enrichment and displayed enhancer activity in settings of injury- and/or Neuregulin1-elicited CM proliferation. Dozens of consensus sequence motifs containing predicted transcription factor binding sites were enriched in genomic regions with regeneration-responsive H3.3 occupancy. Thus, cell-type-specific regulatory programs of tissue regeneration can be revealed by genome-wide H3.3 profiling. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. A weakly nonlinear model for multi-modal evolution of wind-generated long internal waves in a closed basin

    Directory of Open Access Journals (Sweden)

    T. Sakai

    2009-07-01

    Full Text Available A weakly nonlinear evolution model that accounts for multi-modal interaction in a small, continuously stratified lake of variable depth is derived. In particular, an evolution model for the first two vertical modes in a lake that is subject to wind stress forcing is numerically simulated. Defining modal energies, energy transfer between the first and the second vertical modes is calculated for several different forms of the density stratification. Modal energy transfer mainly occurs during reflection of mode-one waves at the vertical end walls, and it is shown that the amount of energy transfer from the first to the second mode is greatly dependent on the shape of the stratification profile. Also, the initial modal energy partition at the wind setup is shown to depend significantly on the penetration depth of the internal shear stress induced by the wind stress, especially if the stress distribution extends into the upper levels of the metalimnion.

  8. Inflammation and axon regeneration.

    Science.gov (United States)

    Benowitz, Larry I; Popovich, Phillip G

    2011-12-01

    The inflammatory response that accompanies neural injury involves multiple cell types and effector molecules with both positive and negative effects. Inflammation is essential for normal regeneration in the peripheral nervous system, and here we review evidence that augmenting inflammation can enhance regeneration in areas of the central nervous system in which it normally does not occur. Within the spinal cord, inflammation enables transplanted sensory neurons to regenerate lengthy axons and enhances the ability of a trophic factor to promote corticospinal tract sprouting. Induction of inflammation in the eye supports survival of retinal ganglion cells and enables them to regenerate injured axons through the optic nerve. These effects are linked to an atypical trophic factor, oncomodulin, along with other, better known molecules. Induction of inflammation within dorsal root ganglia, when combined with other treatments, enables peripheral sensory neurons to regenerate axons into the spinal cord. However, inflammation also has negative effects that impede recovery. In light of the importance of inflammation for neural repair, it is important to identify the specific cell types and molecules responsible for the positive and negative effects of inflammation and to develop treatments that tip the balance to favor repair.

  9. A View From The Sea The Regeneration of Marseille Waterfront: Iconic Buildings And Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Maria Elena Buslacchi

    2014-01-01

    Full Text Available In this paper I will discuss how the isomorphic trend of urban regeneration of waterfronts implies a modeling which is not free from critical points. If we focus on the growing use of art and culture as a tool, both in stable museum form both in ephemeral festival form, we must pair this tool with a local contextualization which requires a deep and multi-prospectic knowledge of the territory. In this context a view “from the sea” becomes fundamental when we think to renovate the identity of the port cities materially and, at the same time, symbolically. First a general introduction about the actual evolution of strategies for regeneration of coastal areas will be given. Then two fundamental specific case-studies in the regeneration of the city of Marseille  will be discussed: Vieux Port and the Esplanade - Fort St-Jean. These areas, studied during my Ph. D. thesis, are meaningful for the connection generated between the local reality and the original project, based on a general purpose model. This paper will try to employ ethnographic methodology to examine which functions have been associated to renewed areas and how these acquired functions can be connected with project steps and with already observed results in other cities. A descriptive approach is predominant in this work; anyway a critical judgment cannot be avoided. This sort of judgment is not to be extended to all the other effects which cannot be directly observed within the case-study.

  10. Genome and transcriptome of the regeneration-competent flatworm, Macrostomum lignano.

    Science.gov (United States)

    Wasik, Kaja; Gurtowski, James; Zhou, Xin; Ramos, Olivia Mendivil; Delás, M Joaquina; Battistoni, Giorgia; El Demerdash, Osama; Falciatori, Ilaria; Vizoso, Dita B; Smith, Andrew D; Ladurner, Peter; Schärer, Lukas; McCombie, W Richard; Hannon, Gregory J; Schatz, Michael

    2015-10-06

    The free-living flatworm, Macrostomum lignano has an impressive regenerative capacity. Following injury, it can regenerate almost an entirely new organism because of the presence of an abundant somatic stem cell population, the neoblasts. This set of unique properties makes many flatworms attractive organisms for studying the evolution of pathways involved in tissue self-renewal, cell-fate specification, and regeneration. The use of these organisms as models, however, is hampered by the lack of a well-assembled and annotated genome sequences, fundamental to modern genetic and molecular studies. Here we report the genomic sequence of M. lignano and an accompanying characterization of its transcriptome. The genome structure of M. lignano is remarkably complex, with ∼75% of its sequence being comprised of simple repeats and transposon sequences. This has made high-quality assembly from Illumina reads alone impossible (N50=222 bp). We therefore generated 130× coverage by long sequencing reads from the Pacific Biosciences platform to create a substantially improved assembly with an N50 of 64 Kbp. We complemented the reference genome with an assembled and annotated transcriptome, and used both of these datasets in combination to probe gene-expression patterns during regeneration, examining pathways important to stem cell function.

  11. Evolution of the collective radiation dose of nuclear reactors from the 2nd through to the 3rd generation and 4th generation sodium-cooled fast reactors

    Directory of Open Access Journals (Sweden)

    Guidez Joel

    2017-01-01

    In the case of sodium-cooled fast reactors (SFRs, the compilation and summarizing of various documentary resources has enabled them to be situated and compared to other types of reactors of the second and third generations (respectively pressurized water reactors in operation and EPR under construction. From these results, it can be seen that the doses received during the operation of SFR are significantly lower for this type of reactor.

  12. Performance of Generating Plant: Managing the Changes. Supporting paper: The evolution of the electricity sector and renewable sources in Italy: opportunities and problems for wind power integration

    Energy Technology Data Exchange (ETDEWEB)

    Salvaderi, Luigi [IEEE Fellow (Italy)

    2008-05-15

    The WEC Committee on the Performance of Generating Plant (PGP) has been collecting and analysing power plant performance statistics worldwide for more than 30 years and has produced regular reports, which include examples of advanced techniques and methods for improving power plant performance through benchmarking. A series of reports from the various working groups was issued in 2008. This document serves as a supporting paper. Sections include: features of Italian energy and electricity; the evolution of liberalisation; support mechanism for renewables; connection to wind farm transmission network; wind source integration into power system; and, final comments.

  13. Low-leakage modular regenerators for gas-turbine engines

    Energy Technology Data Exchange (ETDEWEB)

    Kluka, J.A. [Pratt and Whitney, Middletown, CT (United States); Wilson, D.G. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Mechanical Engineering

    1998-04-01

    One of the significant problems plaguing regenerator designs is seal leakage resulting in a reduction of thermal efficiency. This paper describes the preliminary design and analysis of a new regenerative heat-exchanger concept, called a modular regenerator, that promises to provide improved seal-leakage performance. The modular regenerator concept consists of a ceramic-honeycomb matrix discretized into rectangular blocks, called modules. Separating the matrix into modules substantially reduces the transverse sealing lengths and substantially increases the longitudinal sealing lengths as compared with typical rotary designs. Potential applications can range from small gas-turbine engines for automotive applications to large stationary gas turbines for industrial power generation. Descriptions of two types of modular regenerators are presented including sealing concepts. Results of seal leakage analysis for typical modular regenerators sized for a small gas-turbine engine (120 kW) predict leakage rates under one percent for most seal-clearance heights.

  14. Intra-channel evolution of carbon monoxide and its implication on the regeneration of a monolithic Pt/K/Al{sub 2}O{sub 3} NO{sub x} storage-reduction catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae-Soon; Partridge, William P. [Fuels, Engines, and Emissions Research Center, Oak Ridge National Laboratory, P.O. Box 2008, MS-6472, Oak Ridge, TN 37831-6472 (United States); Epling, William S.; Currier, Neal W.; Yonushonis, Thomas M. [Cummins, Inc., 1900 McKinley Avenue, MC 50227, Columbus, IN 47201 (United States)

    2006-04-30

    Understanding how a reductant evolves and is utilized during regeneration of NO{sub x} storage-reduction catalyst can lead to predictive kinetic models, improved catalysts and energy-efficient engine-catalyst systems. We performed practically relevant NO{sub x} storage/regeneration cycling (56s/4s) experiments over a monolithic Pt/K/Al{sub 2}O{sub 3} catalyst in a bench-flow reactor and resolved multiple transient reactions and exotherms. Carbon monoxide was the reductant and intra-channel speciation and temperature measurements were instrumental in resolving CO chemistry. Gas-phase O{sub 2} reacted with CO very fast over the entire regeneration time, and was depleted at the catalyst front. The resulting exotherm was significant and dissipated slowly over time raising the subsequent storage temperature considerably. NO{sub x} release/reduction by CO was also vigorous and primary NO{sub x} removal occurred at early regeneration times. The NO{sub x}-attributable exotherm was smaller than that of the O{sub 2}-CO reaction, but extended deeper into the front portion of catalyst due to axially distributed NO{sub x} storage. Secondary NO{sub x} release/reduction occurred after the primary and produced NH{sub 3} as the main product. Hydrogen appeared when and where both the O{sub 2} consumption and major NO{sub x} release/reduction were near complete. We proposed that H{sub 2} produced via water-gas shift (WGS) reaction had little impact on O{sub 2} depletion and primary NO{sub x} release/reduction under the conditions studied. Further study is necessary to assess the impact of WGS reaction on secondary NO{sub x} release/reduction. (author)

  15. Extracellular Control of Limb Regeneration

    Science.gov (United States)

    Calve, S.; Simon, H.-G.

    Adult newts possess the ability to completely regenerate organs and appendages. Immediately after limb loss, the extracellular matrix (ECM) undergoes dramatic changes that may provide mechanical and biochemical cues to guide the formation of the blastema, which is comprised of uncommitted stem-like cells that proliferate to replace the lost structure. Skeletal muscle is a known reservoir for blastema cells but the mechanism by which it contributes progenitor cells is still unclear. To create physiologically relevant culture conditions for the testing of primary newt muscle cells in vitro, the spatio-temporal distribution of ECM components and the mechanical properties of newt muscle were analyzed. Tenascin-C and hyaluronic acid (HA) were found to be dramatically upregulated in the amputated limb and were co-expressed around regenerating skeletal muscle. The transverse stiffness of muscle measured in situ was used as a guide to generate silicone-based substrates of physiological stiffness. Culturing newt muscle cells under different conditions revealed that the cells are sensitive to both matrix coating and substrate stiffness: Myoblasts on HA-coated soft substrates display a rounded morphology and become more elongated as the stiffness of the substrate increases. Coating of soft substrates with matrigel or fibronectin enhanced cell spreading and eventual cell fusion.

  16. Cuboid Ni2P as a Bifunctional Catalyst for Efficient Hydrogen Generation from Hydrolysis of Ammonia Borane and Electrocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Du, Yeshuang; Liu, Chao; Cheng, Gongzhen; Luo, Wei

    2017-11-16

    The design of high-performance catalysts for hydrogen generation is highly desirable for the upcoming hydrogen economy. Herein, we report the colloidal synthesis of nanocuboid Ni 2 P by the thermal decomposition of nickel chloride hexahydrate (NiCl 2 ⋅6 H 2 O) and trioctylphosphine. The obtained nanocuboid Ni 2 P was characterized by using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectroscopy. For the first time, the as-synthesized nanocuboid Ni 2 P is used as a bifunctional catalyst for hydrogen generation from the hydrolysis of ammonia borane and electrocatalytic hydrogen evolution. Owing to the strong synergistic electronic effect between Ni and P, the as-synthesized Ni 2 P exhibits catalytic performance that is superior to its counterpart without P doping. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Spectral and temporal breathing self-similar evolution in a fiber amplifier for low-noise transform-limited pulse generation.

    Science.gov (United States)

    Wang, Sijia; Chen, Wei; Qin, Peng; Song, Youjian; Hu, Minglie; Liu, Bowen

    2016-11-15

    We demonstrate a simple scheme for high-power low-noise high-contrast ultrashort pulse generation. It is enabled by the spectral and temporal breathing self-similar pulse evolution with an optimized negative pre-chirp. Experiments and simulations indicate the enhanced tolerances of this scheme to the gain-shaping distortions and pump fluctuations. It can lead to ∼16% increase in the compressed pulse quality with more than a two times wider spectrum and ∼31% reduction in the root-mean-square (rms) relative intensity noise (RIN). Transform-limited pulses as short as 36 fs are generated with the rms RIN of 0.029% (1 kHz-5 MHz) from a 2 m Yb-fiber amplifier.

  18. Infection and Pulp Regeneration

    Directory of Open Access Journals (Sweden)

    Sahng G. Kim

    2016-03-01

    Full Text Available The regeneration of the pulp-dentin complex has been a great challenge to both scientists and clinicians. Previous work has shown that the presence of prior infection may influence the characteristics of tissues formed in the root canal space after regenerative endodontic treatment. The formation of ectopic tissues such as periodontal ligament, bone, and cementum has been observed in the root canal space of immature necrotic teeth with apical periodontitis, while the regeneration of dentin and pulp has been identified in previously non-infected teeth. The current regenerative endodontic therapy utilizes disinfection protocols, which heavily rely on chemical irrigation using conventional disinfectants. From a microbiological point of view, the current protocols may not allow a sufficiently clean root canal microenvironment, which is critical for dentin and pulp regeneration. In this article, the significance of root canal disinfection in regenerating the pulp-dentin complex, the limitations of the current regenerative endodontic disinfection protocols, and advanced disinfection techniques designed to reduce the microorganisms and biofilms in chronic infection are discussed.

  19. MODELING THE ASIAN TSUNAMI EVOLUTION AND PROPAGATION WITH A NEW GENERATION MECHANISM AND A NON-LINEAR DISPERSIVE WAVE MODEL

    Directory of Open Access Journals (Sweden)

    Paul C. Rivera

    2006-01-01

    Full Text Available A common approach in modeling the generation and propagation of tsunami is based on the assumption of a kinematic vertical displacement of ocean water that is analogous to the ocean bottom displacement during a submarine earthquake and the use of a non-dispersive long-wave model to simulate its physical transformation as it radiates outward from the source region. In this study, a new generation mechanism and the use of a highly-dispersive wave model to simulate tsunami inception, propagation and transformation are proposed. The new generation model assumes that transient ground motion during the earthquake can accelerate horizontal currents with opposing directions near the fault line whose successive convergence and divergence generate a series of potentially destructive oceanic waves. The new dynamic model incorporates the effects of earthquake moment magnitude, ocean compressibility through the buoyancy frequency, the effects of focal and water depths, and the orientation of ruptured fault line in the tsunami magnitude and directivity.For tsunami wave simulation, the nonlinear momentum-based wave model includes important wave propagation and transformation mechanisms such as refraction, diffraction, shoaling, partial reflection and transmission, back-scattering, frequency dispersion, and resonant wave-wave interaction. Using this model and a coarse-resolution bathymetry, the new mechanism is tested for the Indian Ocean tsunami of December 26, 2004. A new flooding and drying algorithm that consider waves coming from every direction is also proposed for simulation of inundation of low-lying coastal regions.It is shown in the present study that with the proposed generation model, the observed features of the Asian tsunami such as the initial drying of areas east of the source region and the initial flooding of western coasts are correctly simulated. The formation of a series of tsunami waves with periods and lengths comparable to observations

  20. Regenerated Fe is tasty!

    Science.gov (United States)

    Nuester, J.; Twining, B. S.

    2012-12-01

    Bioavailability of nutrients is an essential factor controlling primary productivity in the ocean. In addition to macronutrients such as nitrogen and phosphorous, availability of the trace element iron unequivocally affects growth rates and community structure of phytoplankton and thereby primary productivity in many ocean regions. External sources of iron such as Aeolian dust, upwelling of Fe-rich waters, and hydrothermal are reduced in high-nutrient low-chlorophyll regions, and most Fe used by phytoplankton has been regenerated by zooplankton. While zooplankton regeneration of Fe was first shown two decades ago, major factors controlling this process such as chemical composition of prey and grazer taxonomy are not well constrained. As pH varies significantly in digestive systems between protozoa and mesozooplankton, we hypothesize that the extent and the bioavailability of regenerated Fe is a function of the digestive physiology. Furthermore, major element components such as silica for diatoms and calcium carbonate for cocolithophores may be able to buffer the pH of digestive systems of different grazer taxa. Such effects may further influence the magnitude and bioavailability of regenerated Fe. In order to constrain the effect of grazer taxonomy and chemical composition of prey on Fe bioavailability, 55Fe-labeled phytoplankton were fed to different grazers and unlabeled phytoplankton were subsequently inoculated to the filtrate of the grazing experiment in the regrowth phase of the experiment, and the uptake of 55Fe into the phytoplankton biomass was monitored over time. A parallel uptake experiment using inorganic 55Fe was used to compare the bioavailability of regenerated and inorganic Fe to the same phytoplankton species. Furthermore, some samples of the inorganic and the regenerated uptake experiments were treated with an oxalate rinse to remove any adsorbed Fe. This allowed us to estimate the adsorption of 55Fe from either source to the cell walls of

  1. Stimulating endogenous cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Amanda eFinan

    2015-09-01

    Full Text Available The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration,a combination of these approaches couldameliorate the overall repair process to incorporate the participation ofmultiple cell players.

  2. Generation of fluorescent silver nanoclusters in reverse micelles using gamma irradiation: low vs. high dosages and spectral evolution with time

    Science.gov (United States)

    Martin, Brett D.; Fontana, Jake; Wang, Zheng; Trammell, Scott A.

    2015-04-01

    Reverse micelles (RMs) containing aqueous solutions of Ag+ ions in their core produce fluorescent Ag nanoclusters (NCs), upon exposure to gamma irradiation. The fluorescence spectra of the NCs evolve over days to weeks after the exposure, and usually show large increases in intensity. Responses of as high as 2.8 × 104 CPS/Gy were reached. A dosage as low as 0.5 Gy (10 % of the lethal dosage for humans) produces NCs having fluorescence intensities higher than background. The RMs can be employed in novel gamma radiation detectors with appearance of fluorescence indicating that radiation was once present. In applications involving detection and tracking of fissile materials, the evolution of the fluorescence spectra over time may provide additional information about the radiation source. A two-phase liquid system is used for RM formation in a simple procedure. It is likely that this synthesis method may be adapted to produce NCs from other metal ions.

  3. Regeneration-Type Nerve Electrode Using Bundled Microfluidic Channels

    Science.gov (United States)

    Suzuki, Takafumi; Kotake, Naoki; Mabuchi, Kunihiko; Takeuchi, Shoji

    Neural interface devices that will allow signals from the human nervous system to control external equipment are extremely important for the next generation of prosthetic systems. A novel multichannel regeneration-type nerve electrode designed to record from and stimulate peripheral nerves has been developed to allow the control of artificial hands and to generate artificial sensations. In this study a novel flexible regeneration microelectrode based on the nerve regeneration principle was designed and fabricated using MEMS technologies. The electrode, which was fabricated on a 25-μm-thick Parylene C substrate, has multiple fluidic channels. Each fluidic channel was 100 μm wide × 30 μm high × 1500 μm long and featured multiple electrodes inside them as recording and stimulating sites. They also served as guidance channels for the regenerating axons.

  4. A study by computer simulation of the generation and evolution of the Earth`s magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, G.A.; Hollerbach, R.; Roberts, P.H.

    1995-12-31

    Until recently very little has been known about the maintenance of the Earth`s magnetic field. The general consensus was that some type of convective motion edits in the Earth`s liquid iron alloy core that is affected by rotational forces in a way that continually generates new magnetic field to replace that which diffuses away. Magnetic-field reversals and secular variation have long been measured but no theory existed to explain these phenomena. To gain an understanding of the basic physical mechanisms of the ``geodynamo,`` we produced the first self-consistent computer simulation of convection and magnetic field generation in a rotating three-dimensional spherical fluid shell as an anologue to the Earth`s convective dynamo. This is a final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  5. Generation of Transparent Oxygen Evolution Electrode Consisting of Regularly Ordered Nanoparticles from Self-Assembly Cobalt Phthalocyanine as a Template.

    Science.gov (United States)

    Ziani, Ahmed; Shinagawa, Tatsuya; Stegenburga, Liga; Takanabe, Kazuhiro

    2016-11-30

    The decoration of (photo)electrodes for efficient photoresponse requires the use of electrocatalysts with good dispersion and high transparency for efficient light absorption by the photoelectrode. As a result of the ease of thermal evaporation and particulate self-assembly growth, the phthalocyanine molecular species can be uniformly deposited layer-by-layer on the surface of substrates. This structure can be used as a template to achieve a tunable amount of catalysts, high dispersion of the nanoparticles, and transparency of the catalysts. In this study, we present a systematic study of the structural and optical properties, surface morphologies, and electrochemical oxygen evolution reaction (OER) performance of cobalt oxide prepared from a phthalocyanine metal precursor. Cobalt phthalocyanine (CoPc) films with different thicknesses were deposited by thermal evaporation on different substrates. The films were annealed at 400 °C in air to form a material with the cobalt oxide phase. The final Co oxide catalysts exhibit high transparency after thermal treatment. Their OER measurements demonstrate well expected mass activity for OER. Thermally evaporated and treated transition metal oxide nanoparticles are attractive for the functionalization of (photo)anodes for water oxidation.

  6. Generation of Transparent Oxygen Evolution Electrode Consisting of Regularly Ordered Nanoparticles from Self-Assembly Cobalt Phthalocyanine as a Template

    KAUST Repository

    Ziani, Ahmed

    2016-11-04

    The decoration of (photo)electrodes for efficient photoresponse requires the use of electrocatalysts with good dispersion and high transparency for efficient light absorption by the photoelectrode. As a result of the ease of thermal evaporation and particulate self-assembly growth, the phthalocyanine molecular species can be uniformly deposited layer-by-layer on the surface of substrates. This structure can be used as a template to achieve a tunable amount of catalysts, high dispersion of the nanoparticles, and transparency of the catalysts. In this study, we present a systematic study of the structural and optical properties, surface morphologies, and electrochemical oxygen evolution reaction (OER) performance of cobalt oxide prepared from a phthalocyanine metal precursor. Cobalt phthalocyanine (CoPc) films with different thicknesses were deposited by thermal evaporation on different substrates. The films were annealed at 400 °C in air to form a material with the cobalt oxide phase. The final Co oxide catalysts exhibit high transparency after thermal treatment. Their OER measurements demonstrate well expected mass activity for OER. Thermally evaporated and treated transition metal oxide nanoparticles are attractive for the functionalization of (photo)anodes for water oxidation.

  7. Jupiter After the 2009 Impact: Hubble Space Telescope Imaging of the Impact-Generated Debris and Its Temporal Evolution

    Science.gov (United States)

    Hammel, H. B.; Wong, M. H.; Clarke, J. T.; de Pater, I.; Fletcher, L. N.; Hueso, R.; Noll, K.; Orton, G. S.; Perez-Hoyos, S.; Sanchez-Lavega, A.; hide

    2010-01-01

    We report Hubble Space Telescope images of Jupiter during the aftermath of an impact by an unknown object in 2009 July, The 2009 impact-created debris field evolved more slowly than those created in 1994 by the collision of the tidally disrupted comet D/Shoemaker-Levy 9 (SL9). The slower evolution, in conjunction with the isolated nature of this single impact, permits a more detailed assessment of the altitudes and meridional motion of the debris than was possible with SL9. The color of the 2009 debris was markedly similar to that seen in 1994, thus this dark debris is likely to be Jovian material that is highly thermally processed. The 2009 impact site differed from the 1994 SL9 sites in UV morphology and contrast lifetime; both are suggestive of the impacting body being asteroidal rather than cometary. Transport of the 2009 Jovian debris as imaged by Hubble shared similarities with transport of volcanic aerosols in Earth's atmosphere after major eruptions.

  8. Generator. Generator

    Energy Technology Data Exchange (ETDEWEB)

    Knoedler, R.; Bossmann, H.P.

    1992-03-12

    The invention refers to a thermo-electric generator, whose main part is a sodium concentration cell. In conventional thermo-electric generators of this kind, the sodium moving from a hot space to a colder space must be transported back to the hot space via a circulation pipe and a pump. The purpose of the invention is to avoid the disadvantages of this return transport. According to the invention, the thermo-electric generator is supported so that it can rotate, so that the position of each space relative to its propinquity to the heat source can be changed at any time.

  9. Bionanomaterials for skin regeneration

    CERN Document Server

    Leonida, Mihaela D

    2016-01-01

    This book gives a concise overview of bionanomaterials with applications for skin regeneration. The advantages and challenges of nanoscale materials are covered in detail, giving a basic view of the skin structure and conditions that require transdermal or topical applications. Medical applications, such as wound healing, care for burns, skin disease, and cosmetic care, such as aging of the skin and photodamage, and how they benefit from bionanomaterials, are described in detail. A final chapter is devoted to the ethical and social issues related to the use of bionanomaterials for skin regeneration. This is an ideal book for researchers in materials science, medical scientists specialized in dermatology, and cosmetic chemists working in formulations. It can also serve as a reference for nanotechnologists, dermatologists, microbiologists, engineers, and polymer chemists, as well as students studying in these fields.

  10. Biomaterials for cardiac regeneration

    CERN Document Server

    Ruel, Marc

    2015-01-01

    This book offers readers a comprehensive biomaterials-based approach to achieving clinically successful, functionally integrated vasculogenesis and myogenesis in the heart. Coverage is multidisciplinary, including the role of extracellular matrices in cardiac development, whole-heart tissue engineering, imaging the mechanisms and effects of biomaterial-based cardiac regeneration, and autologous bioengineered heart valves. Bringing current knowledge together into a single volume, this book provides a compendium to students and new researchers in the field and constitutes a platform to allow for future developments and collaborative approaches in biomaterials-based regenerative medicine, even beyond cardiac applications. This book also: Provides a valuable overview of the engineering of biomaterials for cardiac regeneration, including coverage of combined biomaterials and stem cells, as well as extracellular matrices Presents readers with multidisciplinary coverage of biomaterials for cardiac repair, including ...

  11. Implication of Free Fatty Acids in Thrombin Generation and Fibrinolysis in Vascular Inflammation in Zucker Rats and Evolution with Aging

    Directory of Open Access Journals (Sweden)

    Jérémy Lagrange

    2017-11-01

    Full Text Available Background: The metabolic syndrome (MetS and aging are associated with modifications in blood coagulation factors, vascular inflammation, and increased risk of thrombosis.Objectives: Our aim was to determine concomitant changes in thrombin generation in the blood compartment and at the surface of vascular smooth muscle cells (VSMCs and its interplay with adipokines, free fatty acids (FFA, and metalloproteinases (MMPs in obese Zucker rats that share features of the human MetS.Methods: Obese and age-matched lean Zucker rats were compared at 25 and 80 weeks of age. Thrombin generation was assessed by calibrated automated thrombography (CAT.Results: Endogenous thrombin potential (ETP was increased in obese rats independent of platelets and age. Clot half-lysis time was delayed with obesity and age. Interleukin (IL-1β and IL-13 were increased with obesity and age respectively. Addition of exogenous fibrinogen, leptin, linoleic, or palmitic acid increased thrombin generation in plasma whereas adiponectin had an opposite effect. ETP was increased at the surface of VSMCs from obese rats and addition of exogenous palmitic acid further enhanced ETP values. Gelatinase activity was increased in aorta at both ages in obese rats and MMP-2 activity was increased in VSMCs from obese rats.Conclusions: Our study demonstrated in MetS an early prothrombotic phenotype of the blood compartment reinforced by procoagulant properties of dedifferentiated and inflammatory VSMCs. Mechanisms involved (1 increased fibrinogen and impaired fibrinolysis and (2 increased saturated fatty acids responsible for additive procoagulant effects. Whether specifically targeting this hypercoagulability using direct thrombin inhibitors would improve outcome in MetS is worth investigating.

  12. Low Temperature Regenerator Study.

    Science.gov (United States)

    1979-08-01

    program and as used in Table 4 is typical of well designed Stirling qycle or VM cycle machines, and the gross third-stage refrigeration of 2.785w is a...0. McMahon, "A New Refrigeration Process", Proc. 10th Int. Cong. of Refrig. (1959). 26. G. Walker, Stirling - Cycle Machines, Clarendon Press, Oxford...PERFORMANCE ............ 64 3.1 Introduction ..... 0 ... . ......... ... . 64 3.2 Stirling Cycle Analysis ................. 71 3.2.1 Simple Regenerator Model

  13. Regeneration of Optic Nerve

    Directory of Open Access Journals (Sweden)

    Kwok-Fai So

    2011-05-01

    Full Text Available The optic nerve is part of the central nervous system (CNS and has a structure similar to other CNS tracts. The axons that form the optic nerve originate in the ganglion cell layer of the retina and extend through the optic tract. As a tissue, the optic nerve has the same organization as the white matter of the brain in regard to its glia. There are three types of glial cells: Oligodendrocytes, astrocytes, and microglia. Little structural and functional regeneration of the CNS takes place spontaneously following injury in adult mammals. In contrast, the ability of the mammalian peripheral nervous system (PNS to regenerate axons after injury is well documented. A number of factors are involved in the lack of CNS regeneration, including: (i the response of neuronal cell bodies against the damage; (ii myelin-mediated inhibition by oligodendrocytes; (iii glial scarring, by astrocytes; (iv macrophage infiltration; and (v insufficient trophic factor support. The fundamental difference in the regenerative capacity between CNS and PNS neuronal cell bodies has been the subject of intensive research. In the CNS the target normally conveys a retrograde trophic signal to the cell body. CNS neurons die because of trophic deprivation. Damage to the optic nerve disconnects the neuronal cell body from its target-derived trophic peptides, leading to the death of retinal ganglion cells. Furthermore, the axontomized neurons become less responsive to the peptide trophic signals they do receive. On the other hand, adult PNS neurons are intrinsically responsive to neurotrophic factors and do not lose trophic responsiveness after axotomy. In this talk different strategies to promote optic-nerve regeneration in adult mammals are reviewed. Much work is still needed to resolve many issues. This is a very important area of neuroregeneration and neuroprotection, as currently there is no cure after traumatic optic nerve injury or retinal disease such as glaucoma, which

  14. Particle-in-cell simulations of Magnetic Field Generation, Evolution, and Reconnection in Laser-driven Plasmas

    Science.gov (United States)

    Matteucci, Jack; Moissard, Clément; Fox, Will; Bhattacharjee, Amitava

    2016-10-01

    The advent of high-energy-density physics facilities has introduced the opportunity to experimentally investigate magnetic field dynamics relevant to both ICF and astrophysical plasmas. Recent experiments have demonstrated magnetic reconnection between colliding plasma plumes, where the reconnecting magnetic fields were self-generated in the plasma by the Biermann battery effect. In this study, we simulate these experiments from first principles using 2-D and 3-D particle-in-cell simulations. Simulations self-consistently demonstrate magnetic field generation by the Biermann battery effect, followed by advection by the Hall effect and ion flow. In 2-D simulations, we find in both the collisionless case and the semi-collisional case, defined by eVi × B >> Rei /ne (where Rei is the electron ion momentum transfer) that quantitative agreement with the generalized Ohm's law is only obtained with the inclusion of the pressure tensor. Finally, we document that significant field is destroyed at the reconnection site by the Biermann term, an inverse, `anti-Biermann' effect, which has not been considered previously in analysis of the experiment. The role of the anti-Biermann effect will be compared to standard reconnection mechanisms in 3-D reconnection simulations. This research used resources of the ORLC Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. DoE under Contract No. DE-AC05-00OR22725.

  15. The head-regeneration transcriptome of the planarian Schmidtea mediterranea

    Science.gov (United States)

    2011-01-01

    Background Planarian flatworms can regenerate their head, including a functional brain, within less than a week. Despite the enormous potential of these animals for medical research and regenerative medicine, the mechanisms of regeneration and the molecules involved remain largely unknown. Results To identify genes that are differentially expressed during early stages of planarian head regeneration, we generated a de novo transcriptome assembly from more than 300 million paired-end reads from planarian fragments regenerating the head at 16 different time points. The assembly yielded 26,018 putative transcripts, including very long transcripts spanning multiple genomic supercontigs, and thousands of isoforms. Using short-read data from two platforms, we analyzed dynamic gene regulation during the first three days of head regeneration. We identified at least five different temporal synexpression classes, including genes specifically induced within a few hours after injury. Furthermore, we characterized the role of a conserved Runx transcription factor, smed-runt-like1. RNA interference (RNAi) knockdown and immunofluorescence analysis of the regenerating visual system indicated that smed-runt-like1 encodes a transcriptional regulator of eye morphology and photoreceptor patterning. Conclusions Transcriptome sequencing of short reads allowed for the simultaneous de novo assembly and differential expression analysis of transcripts, demonstrating highly dynamic regulation during head regeneration in planarians. PMID:21846378

  16. Investigation of a Novel NDE Method for Monitoring Thermomechanical Damage and Microstructure Evolution in Ferritic-Martensitic Steels for Generation IV Nuclear Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Peter

    2013-09-30

    The main goal of the proposed project is the development of validated nondestructive evaluation (NDE) techniques for in situ monitoring of ferritic-martensitic steels like Grade 91 9Cr-1Mo, which are candidate materials for Generation IV nuclear energy structural components operating at temperatures up to ~650{degree}C and for steam-generator tubing for sodium-cooled fast reactors. Full assessment of thermomechanical damage requires a clear separation between thermally activated microstructural evolution and creep damage caused by simultaneous mechanical stress. Creep damage can be classified as "negligible" creep without significant plastic strain and "ordinary" creep of the primary, secondary, and tertiary kind that is accompanied by significant plastic deformation and/or cavity nucleation and growth. Under negligible creep conditions of interest in this project, minimal or no plastic strain occurs, and the accumulation of creep damage does not significantly reduce the fatigue life of a structural component so that low-temperature design rules, such as the ASME Section III, Subsection NB, can be applied with confidence. The proposed research project will utilize a multifaceted approach in which the feasibility of electrical conductivity and thermo-electric monitoring methods is researched and coupled with detailed post-thermal/creep exposure characterization of microstructural changes and damage processes using state-of-the-art electron microscopy techniques, with the aim of establishing the most effective nondestructive materials evaluation technique for particular degradation modes in high-temperature alloys that are candidates for use in the Next Generation Nuclear Plant (NGNP) as well as providing the necessary mechanism-based underpinnings for relating the two. Only techniques suitable for practical application in situ will be considered. As the project evolves and results accumulate, we will also study the use of this technique for monitoring other GEN IV

  17. Generation and Evolution of High-Mach Number, Laser-Driven Magnetized Collisionless Shocks in the Laboratory

    CERN Document Server

    Schaeffer, Derek; Haberberger, Dan; Fiksel, Gennady; Bhattacharjee, Amitava; Barnak, Daniel; Hu, Suxing; Germaschewski, Kai

    2016-01-01

    Shocks act to convert incoming supersonic flows to heat, and in collisionless plasmas the shock layer forms on kinetic plasma scales through collective electromagnetic effects. These collisionless shocks have been observed in many space and astrophysical systems [Smith 1975, Smith 1980, Burlaga 2008, Sulaiman 2015], and are believed to accelerate particles, including cosmic rays, to extremely high energies [Kazanas 1986, Loeb 2000, Bamba 2003, Masters 2013, Ackermann 2013]. Of particular importance are the class of high-Mach number, supercritical shocks [Balogh 2013] ($M_A\\gtrsim4$), which must reflect significant numbers of particles back into the upstream to accommodate entropy production, and in doing so seed proposed particle acceleration mechanisms [Blandford 1978, McClements 2001, Caprioli 2014, Matsumoto 2015]. Here we present the first laboratory generation of high-Mach number magnetized collisionless shocks created through the interaction of an expanding laser-driven plasma with a magnetized ambient ...

  18. The evolution of epistemology and concepts in an iterative-generative reflective practice: the importance of small differences.

    Science.gov (United States)

    Bishop, Brian J; Sonn, Christopher C; Drew, Neil M; Contos, Natalie E

    2002-08-01

    Using a contextualist epistemology, it would be expected that regional differences in community psychology would develop over time. It is argued that the epistemology and theory of Western Australian community psychology, while largely based on North American approaches, has developed its own idiosyncracies. These developed through the integration of practice and theory in an "iterative-generative" fashion. The process of development is conceptualized in terms of Schön's and Altman's distinctions between foundational knowledge, and professional and socially responsive knowledge (I. Altman, 1996; D. A. Schön, 1983). It has also been characterized as an incremental development based on the reflection on tacit and conceptual knowledge. From the small differences that have developed between regions, a dialogue can emerge that will better allow understanding of how social forces shape people's actions.

  19. Identifying the conceptual evolution in the electromagnetism teaching, through a UEPS based on an automotive sound system generator of energy

    Directory of Open Access Journals (Sweden)

    Carla Beatriz Spohr

    2017-12-01

    Full Text Available In this study we present the proposal of a Potentially Significant Teaching Unit (UEPS for the teaching of electromagnetism from an electric circuit capable of transforming the sound energy emitted by the loudspeaker into electric energy to recharge the battery. This circuit was considered significant to present the relations between the concepts worked, for example, electric current and electromagnetic induction with the operation of speakers and microphones. For this purpose, academics of the Graduation Course in Natural Sciences (UNIPAMPA - Uruguaiana / RS proposed to elaborate, implement and evaluate a UEPS to teach concepts of electromagnetism for secundary-schooll students, based on the use of the electric circuit that has shown to be an instrument that provokes the motivation of the learner, one of the necessary conditions for the meaningful learning to occur. At the end of the UEPS, the motivation on the part of the academics responsible for teaching with theoretical foundations based on the constructivist theory of Ausubel, as well as on the part of the students of high school through the predisposition to learn, evidenced throughout the meetings was notorious. The results obtained in the present study compare the advances, setbacks and stagnations of the participating students in relation to the evidences of meaningful learning indicated through the answers given by the students to the beginning and the end of the meetings. The data indicate that the conceptual evolution is due to the planning and application of the UEPS, which sought to constantly observe the sequential organization of the contents to be developed, in a manner consistent with the dependency relations that naturally exist between them. In addition to the organization of the contents foreseen in the planning of the UEPS, each meeting was considered prior knowledge of the student, as well as the presence of subsumes in their cognitive structure to enable the anchoring of

  20. Generator. Generator

    Energy Technology Data Exchange (ETDEWEB)

    Bossmann, H.P.; Knoedler, R.

    1992-03-12

    The invention refers to a thermo-electric generator, which contains sodium as the means of heat transport. The sodium moves from the space of higher temperature through a space into the space of lower temperature. One can do without a pump for transporting the sodium back from the space of lower temperature to the space of higher temperature, as the thermo-electric generator can rotate around an axis. It is therefore possible to interchange the position of the two spaces relative to the heat source.

  1. Biomaterial Selection for Tooth Regeneration

    OpenAIRE

    Yuan, Zhenglin; Nie, Hemin; Wang, Shuang; Lee, Chang Hun; Li, Ang; Fu, Susan Y.; Zhou, Hong; Chen, Lili(Institute of Particle and Nuclear Physics, Henan Normal University, Xinxiang 453007, China); MAO, JEREMY J.

    2011-01-01

    Biomaterials are native or synthetic polymers that act as carriers for drug delivery or scaffolds for tissue regeneration. When implanted in vivo, biomaterials should be nontoxic and exert intended functions. For tooth regeneration, biomaterials have primarily served as a scaffold for (1) transplanted stem cells and/or (2) recruitment of endogenous stem cells. This article critically synthesizes our knowledge of biomaterial use in tooth regeneration, including the selection of native and/or s...

  2. [Fecal carriage of third-generation cephalosporins-resistant Enterobacteriaceae in asymptomatic young adults: evolution between 1999 and 2009].

    Science.gov (United States)

    Janvier, F; Mérens, A; Delaune, D; Soler, C; Cavallo, J-D

    2011-04-01

    The aim of this work was to evaluate the fecal carriage of third generation cephalosporins resistant Enterobacteriaceae in nonhospitalized asymptomatic young adults. A total of 517 normal fecal samples were spread onto plates agar containing cefotaxime. Isolated strains were identified and studied with agar disk diffusion antibiogram, minimal inhibition concentration in liquid medium and phenotypic and molecular study. Data were compared with a previous study realised in the same conditions in 1999. In 2009, the prevalence of cefotaxime resistant enterobacteria was 4.2%. Of these 22 Enterobacteriaceae, 11 harboured overexpressed cephalosporinase and 11 produced extended-spectrum-betalactamase (ESBL). Among ESBL, six E. coli produced CTX-M from group 1 (n=6), group 2 (n=1), group 9 (n=2), one E. coli produced SHV-12 and one Klebsiella pneumoniae produced CTX-M from group 1. All ESBL were multiresistant. In 1999, all the CTX resistant isolates recovered produced a cephalosporinase and no ESBL was found. This study highlights the increasing prevalence of fecal carriage of ESBL-producing enterobacteria in asymptomatic young patients in the community (0% in 1999 versus 2.1% in 2009; P<0.001). E. Coli with CTX-M from group 1 was the most frequent ESBL identified, while fecal carriage of Enterobacteteriaceae overproducing cephalosporinase was similar (2.1%). Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  3. Next Generation Sequencing of Chromosome-Specific Libraries Sheds Light on Genome Evolution in Paleotetraploid Sterlet (Acipenser ruthenus).

    Science.gov (United States)

    Andreyushkova, Daria A; Makunin, Alexey I; Beklemisheva, Violetta R; Romanenko, Svetlana A; Druzhkova, Anna S; Biltueva, Larisa B; Serdyukova, Natalya A; Graphodatsky, Alexander S; Trifonov, Vladimir A

    2017-11-10

    Several whole genome duplication (WGD) events followed by rediploidization took place in the evolutionary history of vertebrates. Acipenserids represent a convenient model group for investigation of the consequences of WGD as their representatives underwent additional WGD events in different lineages resulting in ploidy level variation between species, and these processes are still ongoing. Earlier, we obtained a set of sterlet (Acipenser ruthenus) chromosome-specific libraries by microdissection and revealed that they painted two or four pairs of whole sterlet chromosomes, as well as additional chromosomal regions, depending on rediploidization status and chromosomal rearrangements after genome duplication. In this study, we employed next generation sequencing to estimate the content of libraries derived from different paralogous chromosomes of sterlet. For this purpose, we aligned the obtained reads to the spotted gar (Lepisosteus oculatus) reference genome to reveal syntenic regions between these two species having diverged 360 Mya. We also showed that the approach is effective for synteny prediction at various evolutionary distances and allows one to clearly distinguish paralogous chromosomes in polyploid genomes. We postulated that after the acipenserid-specific WGD sterlet karyotype underwent multiple interchromosomal rearrangements, but different chromosomes were involved in this process unequally.

  4. Next Generation Sequencing of Chromosome-Specific Libraries Sheds Light on Genome Evolution in Paleotetraploid Sterlet (Acipenser ruthenus

    Directory of Open Access Journals (Sweden)

    Daria A. Andreyushkova

    2017-11-01

    Full Text Available Several whole genome duplication (WGD events followed by rediploidization took place in the evolutionary history of vertebrates. Acipenserids represent a convenient model group for investigation of the consequences of WGD as their representatives underwent additional WGD events in different lineages resulting in ploidy level variation between species, and these processes are still ongoing. Earlier, we obtained a set of sterlet (Acipenser ruthenus chromosome-specific libraries by microdissection and revealed that they painted two or four pairs of whole sterlet chromosomes, as well as additional chromosomal regions, depending on rediploidization status and chromosomal rearrangements after genome duplication. In this study, we employed next generation sequencing to estimate the content of libraries derived from different paralogous chromosomes of sterlet. For this purpose, we aligned the obtained reads to the spotted gar (Lepisosteus oculatus reference genome to reveal syntenic regions between these two species having diverged 360 Mya. We also showed that the approach is effective for synteny prediction at various evolutionary distances and allows one to clearly distinguish paralogous chromosomes in polyploid genomes. We postulated that after the acipenserid-specific WGD sterlet karyotype underwent multiple interchromosomal rearrangements, but different chromosomes were involved in this process unequally.

  5. Promoting Active Species Generation by Electrochemical Activation in Alkaline Media for Efficient Electrocatalytic Oxygen Evolution in Neutral Media.

    Science.gov (United States)

    Xu, Kun; Cheng, Han; Liu, Linqi; Lv, Haifeng; Wu, Xiaojun; Wu, Changzheng; Xie, Yi

    2017-01-11

    In this study, by using dicobalt phosphide nanoparticles as precatalysts, we demonstrated that electrochemical activation of metallic precatalysts in alkaline media (comparing with directly electrochemical activation in neutral media) could significantly promote the OER catalysis in neutral media, specifically realizing a 2-fold enhanced activity and meanwhile showing a greatly decreased overpotential of about 100 mV at 10 mA cm(-2). Compared directly with electrochemical activation in neutral media, the electrochemical activation in harsh alkaline media could easily break the strong Co-Co bond and promote active species generation on the surface of metallic Co2P, thus accounting for the enhancement of neutral OER activity, which is also evidenced by HRTEM and the electrochemical double-layer capacitance measurement. The activation of electrochemical oxidation of metallic precatalysts in alkaline media enhanced neutral OER catalysis could also be observed on CoP nanoparticles and Ni2P nanoparticles, suggesting this is a generic strategy. Our work highlights that the activation of electrochemical oxidation of metallic precatalysts in alkaline media would pave new avenues for the design of advanced neutral OER electrocatalysts.

  6. Bioactive and Biodegradable Nanocomposites and Hybrid Biomaterials for Bone Regeneration

    Directory of Open Access Journals (Sweden)

    Kibret Mequanint

    2012-06-01

    Full Text Available Strategies for bone tissue engineering and regeneration rely on bioactive scaffolds to mimic the natural extracellular matrix and act as templates onto which cells attach, multiply, migrate and function. Of particular interest are nanocomposites and organic-inorganic (O/I hybrid biomaterials based on selective combinations of biodegradable polymers and bioactive inorganic materials. In this paper, we review the current state of bioactive and biodegradable nanocomposite and O/I hybrid biomaterials and their applications in bone regeneration. We focus specifically on nanocomposites based on nano-sized hydroxyapatite (HA and bioactive glass (BG fillers in combination with biodegradable polyesters and their hybrid counterparts. Topics include 3D scaffold design, materials that are widely used in bone regeneration, and recent trends in next generation biomaterials. We conclude with a perspective on the future application of nanocomposites and O/I hybrid biomaterials for regeneration of bone.

  7. Public private co-operation in urban regeneration investment planning

    DEFF Research Database (Denmark)

    Jensen, Jesper Ole; Larsen, Jacob Norvig

    . Previous research shows that area-based urban regeneration generates immense private investments, primarily from local property owners, but also from external developers. For the latter, external private investments can enable large and strategic investments that contributes positively to the urban......Increasing renovation costs and ever more limited public funding for urban regeneration in combination with a political desire to stimulate the development of a sense of ownership in urban regeneration neighbourhoods has brought about a growing interest in attracting private sector funding...... development. However, we believe that municipalities can become much better at attracting private investors and developers, partly because there is knowledge about the motives and backgrounds for the developers' engagement in the urban regeneration. Based on data from a number of case studies and interviews...

  8. Synthetic Phage for Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    So Young Yoo

    2014-01-01

    Full Text Available Controlling structural organization and signaling motif display is of great importance to design the functional tissue regenerating materials. Synthetic phage, genetically engineered M13 bacteriophage has been recently introduced as novel tissue regeneration materials to display a high density of cell-signaling peptides on their major coat proteins for tissue regeneration purposes. Structural advantages of their long-rod shape and monodispersity can be taken together to construct nanofibrous scaffolds which support cell proliferation and differentiation as well as direct orientation of their growth in two or three dimensions. This review demonstrated how functional synthetic phage is designed and subsequently utilized for tissue regeneration that offers potential cell therapy.

  9. Revolutionizing Our Understanding of AGN Feedback and its Importance to Galaxy Evolution in the Era of the Next Generation Very Large Array

    Science.gov (United States)

    Nyland, Kristina; Harwood, Jeremy; Jagannathan, Preshanth; Mukherjee, Dipanjan; Lacy, Mark; Morabito, Leah; Maksym, W. Peter; Kimball, Amy; Alatalo, Katherine; Bicknell, Geoff; Patil, Pallavi; Emonts, Bjorn

    2018-01-01

    Energetic feedback by Active Galactic Nuclei (AGNs) likely plays an important evolutionary role in the regulation of star formation (SF) on galactic scales. However, the effects of this feedback under different host galaxy conditions and environments remain unknown due to the scarcity of observational examples of this process in action given the limitations of current telescopes. The Next Generation Very Large Array (ngVLA) will serve as a transformational new tool in our understanding of how radio jets affect their surroundings. Current plans for the ngVLA consist of an array of 214 18m antennas with baselines out to 500 km operating over a frequency range of 1-115 GHz. By combining deep, broadband continuum data with measurements of the atomic and/or molecular gas content and kinematics, the ngVLA will quantify the energetic impact of radio jets hosted by gas-rich galaxies as the jets interact with the star-forming gas reservoirs of their hosts. Here, we evaluate the progress in our understanding of AGN feedback and its connection to galaxy evolution that may be accomplished with the unique capabilities of the ngVLA. Our analysis includes simulations of ngVLA observations of redshifted analogs of nearby AGNs with diverse properties, along with examples of opportunities for multiwavelength synergies with current and future next-generation instruments that are currently under development.

  10. Macrophages in tissue repair, regeneration, and fibrosis

    Science.gov (United States)

    Wynn, Thomas A.; Vannella, Kevin M.

    2016-01-01

    Inflammatory monocytes and resident tissue macrophages are key regulators of tissue repair, regeneration, and fibrosis. Following tissue injury, monocytes and macrophages undergo marked phenotypic and functional changes to play critical roles during the initiation, maintenance, and resolution phases of tissue repair. Disturbances in macrophage function can lead to aberrant repair, with uncontrolled inflammatory mediator and growth factor production, deficient generation of anti-inflammatory macrophages, or failed communication between macrophages and epithelial cells, endothelial cells, fibroblasts, and stem or tissue progenitor cells all contributing to a state of persistent injury, which may lead to the development of pathological fibrosis. In this review, we discuss the mechanisms that instruct macrophages to adopt pro-inflammatory, pro-wound healing, pro-fibrotic, anti-inflammatory, anti-fibrotic, pro-resolving, and tissue regenerating phenotypes following injury, and highlight how some of these mechanisms and macrophage activation states could be exploited therapeutically. PMID:26982353

  11. Repeat rainfall simulation experiments for assessing the evolution of overland flow generation and inter-rill erosion following wildfire

    Science.gov (United States)

    Keizer, Jan Jacob; Malvar, Maruxa; Prats, Sergio; Nunes, João. Pedro

    2010-05-01

    The EROSFIRE project selected field rainfall simulation experiments (RSE's) as a time-and cost-effective approach to gather runoff and soil loss data under the rapidly changing conditions typical for commercial eucalypt plantations in Portugal following wildfires. These RSE data were first and foremost envisaged for initial parameterization and calibration of a physically-based model like MEFIDIS. Subsequent model assessment at larger spatial scales would then be based on slope-scale erosion plot data collected at a small number of selected sites. The present work, however, will in principle be confined to an analysis of the measurement results of the RSE's in two recently burnt eucalypt plantations. Repeat RSE's were carried out in two adjacent but contrasting eucalypt stands on steep hillslopes in north-central Portugal. This involved six occasions ranging from 3 to 24 months after a moderate severity fire in July 2005. A paired-plot experimental design was employed that comprised two pairs of RSE's at each site and occasion. From a grand total of 46 RSE's: (i) 24 and 22 RSE's involved application rates of 45-50 and 80-85 mm h-1, respectively; (ii) 22 took place in a stand that had been ploughed in downslope direction several years before the wildfire and 24 in an unploughed stand. The results showed a clear tendency for extreme-intensity RSE's to produce higher runoff amounts and greater soil and organic matter losses than the simultaneous high-intensity RSE's on the neighbouring plots. Nonetheless, there were marked exceptions, both in space (for one of the plot pairs) and time (under intermediate soil water repellency conditions). Also, overland flow generation and erosion varied significantly along the various field campaigns. This temporal pattern noticeably differed from a straightforward decline with time-after-fire, rather suggesting a seasonal component that reflected broad variations in topsoil water repellency. The ploughed site produced less runoff

  12. Constellation-X to Generation-X: evolution of large collecting area moderate resolution grazing incidence x-ray telescopes to larger area high-resolution adjustable optics

    Science.gov (United States)

    Reid, Paul B.; Cameron, Robert A.; Cohen, Lester; Elvis, Martin; Gorenstein, Paul; Jerius, Diab; Petre, Robert; Podgorski, William A.; Schwartz, Daniel A.; Zhang, William W.

    2004-10-01

    Large collecting area x-ray telescopes are designed to study the early Universe, trace the evolution of black holes, stars and galaxies, study the chemical evolution of the Universe, and study matter in extreme environments. The Constellation-X mission (Con-X), planned for launch in 2016, will provide ~ 10^4 cm^2 collecting area with 15 arc-sec resolution, with a goal of 5 arc-sec. Future missions require larger collecting area and finer resolution. Generation-X (Gen-X), a NASA Visions Mission, will achieve 100 m^2 effective area at 1 keV and angular resolution of 0.1 arc-sec, half power diameter. We briefly describe the Con-X flowdown of imaging requirements to reflector figure error. To meet requirements beyond Con-X, Gen-X optics will be thinner and more accurately shaped than has ever been accomplished. To meet these challenging goals, we incorporate for the first time active figure control with grazing incidence optics. Piezoelectric material will be deposited in discrete cells directly on the back surface of the optical segments, with the strain directions oriented parallel to the surface. Differential strain between the two layers of the mirror causes localized bending in two directions, enabling local figure control. Adjusting figure on-orbit eases fabrication and metrology. The ability to make changes to mirror figure adds margin by mitigating risk due to launch-induced deformations and/or on-orbit degradation. We flowdown the Gen-X requirements to mirror figure and four telescope designs, and discuss various trades between the designs.

  13. Nanobiomaterials for neural regeneration

    Directory of Open Access Journals (Sweden)

    Nuan Chen

    2016-01-01

    Full Text Available Diseases and disorders associated with nervous system such as injuries by trauma and neurodegeneration are shown to be one of the most serious problems in medicine, requiring innovative strategies to trigger and enhance the nerve regeneration. Tissue engineering aims to provide a highly biomimetic environment by using a combination of cells, materials and suitable biological cues, by which the lost body part may be regenerated or even fully rebuilt. Electrospinning, being able to produce extracellular matrix (ECM-like nanostructures with great flexibility in design and choice of materials, have demonstrated their great potential for fabrication of nerve tissue engineered scaffolds. The review here begins with a brief description of the anatomy of native nervous system, which provides basic knowledge and ideas for the design of nerve tissue scaffolds, followed by five main parts in the design of electrospun nerve tissue engineered scaffolds including materials selection, structural design, in vitro bioreactor, functionalization and cellular support. Performances of biomimetic electrospun nanofibrous nerve implant devices are also reviewed. Finally, future directions for advanced electrospun nerve tissue engineered scaffolds are discussed.

  14. Manipulations to regenerate aspen ecosystems

    Science.gov (United States)

    Wayne D. Shepperd

    2001-01-01

    Vegetative regeneration of aspen can be initiated through manipulations that provide hormonal stimulation, proper growth environment, and sucker protection - the three elements of the aspen regeneration triangle. The correct course of action depends upon a careful evaluation of the size, vigor, age, and successional status of the existing clone. Soils and site...

  15. Acoustic field modulation in regenerators

    Science.gov (United States)

    Hu, J. Y.; Wang, W.; Luo, E. C.; Chen, Y. Y.

    2016-12-01

    The regenerator is a key component that transfers energy between heat and work. The conversion efficiency is significantly influenced by the acoustic field in the regenerator. Much effort has been spent to quantitatively determine this influence, but few comprehensive experimental verifications have been performed because of difficulties in modulating and measuring the acoustic field. In this paper, a method requiring two compressors is introduced and theoretically investigated that achieves acoustic field modulation in the regenerator. One compressor outputs the acoustic power for the regenerator; the other acts as a phase shifter. A RC load dissipates the acoustic power out of both the regenerator and the latter compressor. The acoustic field can be modulated by adjusting the current in the two compressors and opening the RC load. The acoustic field is measured with pressure sensors instead of flow-field imaging equipment, thereby greatly simplifying the experiment.

  16. The Basis of Muscle Regeneration

    Directory of Open Access Journals (Sweden)

    Antonio Musarò

    2014-01-01

    Full Text Available Muscle regeneration recapitulates many aspects of embryonic myogenesis and is an important homeostatic process of the adult skeletal muscle, which, after development, retains the capacity to regenerate in response to appropriate stimuli, activating the muscle compartment of stem cells, namely, satellite cells, as well as other precursor cells. Moreover, significant evidence suggests that while stem cells represent an important determinant for tissue regeneration, a “qualified” environment is necessary to guarantee and achieve functional results. It is therefore plausible that the loss of control over these cell fate decisions could lead to a pathological transdifferentiation, leading to pathologic defects in the regenerative process. This review provides an overview about the general aspects of muscle development and discusses the cellular and molecular aspects that characterize the five interrelated and time-dependent phases of muscle regeneration, namely, degeneration, inflammation, regeneration, remodeling, and maturation/functional repair.

  17. Materializing Heart Regeneration: Biomimicry of Key Observations in Cell Transplantation Therapies and Natural Cardiac Regeneration

    Science.gov (United States)

    Kong, Yen P.; Jongpaiboonkit, Leena

    2016-07-01

    New regenerative paradigms are needed to address the growing global problem of heart failure as existing interventions are unsatisfactory. Outcomes from the current paradigm of cell transplantation have not been stellar but the mechanistic knowledge learned from them is instructive in the development of future paradigms. An emerging biomaterial-based approach incorporating key mechanisms and additional ones scrutinized from the process of natural heart regeneration in zebrafish may become the next evolution in cardiac repair. We highlight, with examples, tested key concepts and pivotal ones that may be integrated into a successful therapy.

  18. Solving local problems through local involvement? Experiences from Danish Urban Regeneration

    DEFF Research Database (Denmark)

    Jensen, Jesper Ole

    Over the last decades, the Danish Urban Regeneration Program has – in line with public well-fare politics in general - increasingly turned towards efforts to generate more local involvement in solving local urban problems. Whereas former periods of urban regeneration have been mainly based on top...... agenda, and what can be learned from the development so far. Although ‘local involvement’ is a commonly used term in various urban regeneration programs, it can have many different meanings and implications. Therefore, the paper will discuss local involvement in the urban regeneration based on four...

  19. Plant grafting: insights into tissue regeneration.

    Science.gov (United States)

    Melnyk, Charles W

    2017-02-01

    For millennia, people have cut and joined different plants together through a process known as grafting. The severed tissues adhere, the cells divide and the vasculature differentiates through a remarkable process of regeneration between two genetically distinct organisms as they become one. Grafting is becoming increasingly important in horticulture where it provides an efficient means for asexual propagation. Grafting also combines desirable roots and shoots to generate chimeras that are more vigorous, more pathogen resistant and more abiotic stress resistant. Thus, it presents an elegant and efficient way to improve plant productivity in vegetables and trees using traditional techniques. Despite this horticultural importance, we are only beginning to understand how plants regenerate tissues at the graft junction. By understanding grafting better, we can shed light on fundamental regeneration pathways and the basis for self/non-self recognition. We can also better understand why many plants efficiently graft whereas others cannot, with the goal of improving grafting so as to broaden the range of grafted plants to create even more desirable chimeras. Here, I review the latest findings describing how plants graft and provide insight into future directions in this emerging field.

  20. Carbon regeneration in the Cariaco Basin, Venezuela

    Directory of Open Access Journals (Sweden)

    Arístides Marquez

    Full Text Available Abstract The carbon regeneration in the water column of the Cariaco Basin (Venezuela was investigated using a regression model of total alkalinity (TA and the concentration of total inorganic carbon (TCO2. Primary productivity (PP was determined from the inorganic carbon fraction assimilated by phytoplankton and the variation of the 22 and 23ºC isotherm was used as an indicator of coastal upwelling. The results indicate that CO2 levels were lowest (1962 µmol/kg at the surface and increased to 2451 µmol/kg below the oxic-anoxic redox interface. The vertical regeneration distribution of carbon was dominated (82% by organic carbon originating from the soft tissue of photosynthetic organisms, whereas 18% originated from the dissolution of biogenic calcite. The regeneration of organic carbon was highest in the surface layer in agreement with the primary productivity values. However, at the oxic-anoxic interface a second more intense maximum was detected (70-80%, generated by chemotrophic respiration of organic material by microorganisms. The percentages in the anoxic layers were lower than in the oxic zone because aerobic decomposition occurs more rapidly than anaerobic respiration of organic material because more labile fractions of organic carbon have already been mineralized in the upper layers.

  1. Vertically- and horizontally-transmitted memories – the fading boundaries between regeneration and inheritance in planaria

    Directory of Open Access Journals (Sweden)

    Moran Neuhof

    2016-09-01

    Full Text Available The Weismann barrier postulates that genetic information passes only from the germline to the soma and not in reverse, thus providing an obstacle to the inheritance of acquired traits. Certain organisms such as planaria – flatworms that can reproduce through asymmetric fission – avoid the limitations of this barrier, thus blurring the distinction between the processes of inheritance and development. In this paper, we re-evaluate canonical ideas about the interaction between developmental, genetic and evolutionary processes through the lens of planaria. Biased distribution of epigenetic effects in asymmetrically produced parts of a regenerating organism could increase variation and therefore affect the species' evolution. The maintenance and fixing of somatic experiences, encoded via stable biochemical or physiological states, may contribute to evolutionary processes in the absence of classically defined generations. We discuss different mechanisms that could induce asymmetry between the two organisms that eventually develop from the regenerating parts, including one particularly fascinating source – the potential capacity of the brain to produce long-lasting epigenetic changes.

  2. Live imaging reveals the progenitors and cell dynamics of limb regeneration

    Science.gov (United States)

    Alwes, Frederike; Enjolras, Camille; Averof, Michalis

    2016-01-01

    Regeneration is a complex and dynamic process, mobilizing diverse cell types and remodelling tissues over long time periods. Tracking cell fate and behaviour during regeneration in active adult animals is especially challenging. Here, we establish continuous live imaging of leg regeneration at single-cell resolution in the crustacean Parhyale hawaiensis. By live recordings encompassing the first 4-5 days after amputation, we capture the cellular events that contribute to wound closure and morphogenesis of regenerating legs with unprecedented resolution and temporal detail. Using these recordings we are able to track cell lineages, to generate fate maps of the blastema and to identify the progenitors of regenerated epidermis. We find that there are no specialized stem cells for the epidermis. Most epidermal cells in the distal part of the leg stump proliferate, acquire new positional values and contribute to new segments in the regenerating leg. DOI: http://dx.doi.org/10.7554/eLife.19766.001 PMID:27776632

  3. Bone regeneration in dentistry

    Science.gov (United States)

    Tonelli, Paolo; Duvina, Marco; Barbato, Luigi; Biondi, Eleonora; Nuti, Niccolò; Brancato, Leila; Rose, Giovanna Delle

    2011-01-01

    Summary The edentulism of the jaws and the periodontal disease represent conditions that frequently leads to disruption of the alveolar bone. The loss of the tooth and of its bone of support lead to the creation of crestal defects or situation of maxillary atrophy. The restoration of a functional condition involves the use of endosseous implants who require adequate bone volume, to deal with the masticatory load. In such situations the bone need to be regenerated, taking advantage of the biological principles of osteogenesis, osteoinduction and osteoconduction. Several techniques combine these principles with different results, due to the condition of the bone base on which we operate changes, the surgical technique that we use, and finally for the bone metabolic conditions of the patient who can be in a state of systemic osteopenia or osteoporosis; these can also affect the result of jaw bone reconstruction. PMID:22461825

  4. An ancient dental gene network regulates development and continuous regeneration of teeth in sharks

    OpenAIRE

    Rasch, L.; Cooper, R.; Martin, K.; Metscher, B.; Underwood, Charlie J.; Fraser, G.

    2016-01-01

    The evolution of oral teeth is considered a major contributor to the overall success of jawed vertebrates. This is especially apparent in cartilaginous fishes including sharks and rays, which develop elaborate arrays of highly specialized teeth, organized in rows and retain the capacity for life-long regeneration. Perpetual regeneration of oral teeth has been either lost or highly reduced in many other lineages including important developmental model species, so cartilaginous fishes are uniqu...

  5. Biomaterial selection for tooth regeneration.

    Science.gov (United States)

    Yuan, Zhenglin; Nie, Hemin; Wang, Shuang; Lee, Chang Hun; Li, Ang; Fu, Susan Y; Zhou, Hong; Chen, Lili; Mao, Jeremy J

    2011-10-01

    Biomaterials are native or synthetic polymers that act as carriers for drug delivery or scaffolds for tissue regeneration. When implanted in vivo, biomaterials should be nontoxic and exert intended functions. For tooth regeneration, biomaterials have primarily served as a scaffold for (1) transplanted stem cells and/or (2) recruitment of endogenous stem cells. This article critically synthesizes our knowledge of biomaterial use in tooth regeneration, including the selection of native and/or synthetic polymers, three-dimensional scaffold fabrication, stem cell transplantation, and stem cell homing. A tooth is a complex biological organ. Tooth loss represents the most common organ failure. Tooth regeneration encompasses not only regrowth of an entire tooth as an organ, but also biological restoration of individual components of the tooth including enamel, dentin, cementum, or dental pulp. Regeneration of tooth root represents perhaps more near-term opportunities than the regeneration of the whole tooth. In the adult, a tooth owes its biological vitality, arguably more, to the root than the crown. Biomaterials are indispensible for the regeneration of tooth root, tooth crown, dental pulp, or an entire tooth. © Mary Ann Liebert, Inc.

  6. Biomaterial Selection for Tooth Regeneration

    Science.gov (United States)

    Yuan, Zhenglin; Nie, Hemin; Wang, Shuang; Lee, Chang Hun; Li, Ang; Fu, Susan Y.; Zhou, Hong

    2011-01-01

    Biomaterials are native or synthetic polymers that act as carriers for drug delivery or scaffolds for tissue regeneration. When implanted in vivo, biomaterials should be nontoxic and exert intended functions. For tooth regeneration, biomaterials have primarily served as a scaffold for (1) transplanted stem cells and/or (2) recruitment of endogenous stem cells. This article critically synthesizes our knowledge of biomaterial use in tooth regeneration, including the selection of native and/or synthetic polymers, three-dimensional scaffold fabrication, stem cell transplantation, and stem cell homing. A tooth is a complex biological organ. Tooth loss represents the most common organ failure. Tooth regeneration encompasses not only regrowth of an entire tooth as an organ, but also biological restoration of individual components of the tooth including enamel, dentin, cementum, or dental pulp. Regeneration of tooth root represents perhaps more near-term opportunities than the regeneration of the whole tooth. In the adult, a tooth owes its biological vitality, arguably more, to the root than the crown. Biomaterials are indispensible for the regeneration of tooth root, tooth crown, dental pulp, or an entire tooth. PMID:21699433

  7. An energy storage and regeneration system

    DEFF Research Database (Denmark)

    2006-01-01

    caverns. When the energy demand exceeds the power production capacity of the plant, the stored gases are burned and the thermal energy is converted into electricity in gas turbine generators. The regenerated electrical power is then used to supplement the output of the electric power plant to meet......  The present invention relates to a method and a system for storing excess energy produced by an electric power plant during periods of lower energy demand than the power plant production capacity. The excess energy is stored by hydrolysis of water and storage of hydrogen and oxygen in underground...

  8. Imaging regenerating bone tissue based on neural networks applied to micro-diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Campi, G.; Pezzotti, G. [Institute of Crystallography, CNR, via Salaria Km 29.300, I-00015, Monterotondo Roma (Italy); Fratini, M. [Centro Fermi -Museo Storico della Fisica e Centro Studi e Ricerche ' Enrico Fermi' , Roma (Italy); Ricci, A. [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, D-22607 Hamburg (Germany); Burghammer, M. [European Synchrotron Radiation Facility, B. P. 220, F-38043 Grenoble Cedex (France); Cancedda, R.; Mastrogiacomo, M. [Istituto Nazionale per la Ricerca sul Cancro, and Dipartimento di Medicina Sperimentale dell' Università di Genova and AUO San Martino Istituto Nazionale per la Ricerca sul Cancro, Largo R. Benzi 10, 16132, Genova (Italy); Bukreeva, I.; Cedola, A. [Institute for Chemical and Physical Process, CNR, c/o Physics Dep. at Sapienza University, P-le A. Moro 5, 00185, Roma (Italy)

    2013-12-16

    We monitored bone regeneration in a tissue engineering approach. To visualize and understand the structural evolution, the samples have been measured by X-ray micro-diffraction. We find that bone tissue regeneration proceeds through a multi-step mechanism, each step providing a specific diffraction signal. The large amount of data have been classified according to their structure and associated to the process they came from combining Neural Networks algorithms with least square pattern analysis. In this way, we obtain spatial maps of the different components of the tissues visualizing the complex kinetic at the base of the bone regeneration.

  9. Active Nanomaterials to Meet the Challenge of Dental Pulp Regeneration

    Directory of Open Access Journals (Sweden)

    Laetitia Keller

    2015-11-01

    Full Text Available The vitality of the pulp is fundamental to the functional life of the tooth. For this aim, active and living biomaterials are required to avoid the current drastic treatment, which is the removal of all the cellular and molecular content regardless of its regenerative potential. The regeneration of the pulp tissue is the dream of many generations of dental surgeons and will revolutionize clinical practices. Recently, the potential of the regenerative medicine field suggests that it would be possible to achieve such complex regeneration. Indeed, three crucial steps are needed: the control of infection and inflammation and the regeneration of lost pulp tissues. For regenerative medicine, in particular for dental pulp regeneration, the use of nano-structured biomaterials becomes decisive. Nano-designed materials allow the concentration of many different functions in a small volume, the increase in the quality of targeting, as well as the control of cost and delivery of active molecules. Nanomaterials based on extracellular mimetic nanostructure and functionalized with multi-active therapeutics appear essential to reverse infection and inflammation and concomitantly to orchestrate pulp cell colonization and differentiation. This novel generation of nanomaterials seems very promising to meet the challenge of the complex dental pulp regeneration.

  10. Comparison of Callus induction and plant regeneration

    African Journals Online (AJOL)

    Sang-Hoon Lee

    2012-02-21

    Feb 21, 2012 ... regeneration frequency from transgenic callus, but also useful for molecular breeding of tall fescue through ... Plant regeneration. The plant regeneration culture medium (Lee et al., 2007) was used to regenerate plants from the mature seed-derived calluses. It was ..... bioassays with tobacco tissue cultures.

  11. Ultraviolet irradiation initiates ectopic foot formation in regenerating ...

    Indian Academy of Sciences (India)

    Unknown

    [Ghaskadbi S S, Shetye L, Chiplonkar S and Ghaskadbi S 2005 Ultraviolet irradiation initiates ectopic foot formation in regenerating hydra and promotes budding; J. Biosci. 30 177–182]. 1. Introduction. Hydra, a member of the phylum Cnidaria, has an oral- aboral body axis and exhibits a remarkable ability to re- generate.

  12. An active magnetic regenerator device

    DEFF Research Database (Denmark)

    2015-01-01

    A rotating active magnetic regenerator (AMR) device comprising two or more regenerator beds, a magnet arrangement and a valve arrangement. The valve arrangement comprises a plurality of valve elements arranged substantially immovably with respect to the regenerator beds along a rotational direction....... A cam surface is arranged substantially immovably with respect to the magnet arrangement along the rotational direction, and comprises a plurality of cam elements arranged to cooperate with the valve elements in order to control opening degrees of the valve elements, in accordance with a relative...... position of the cam elements and the valve elements. Thereby the opening degree of each valve element is controlled in accordance with a relative angular position of the regenerator beds and the magnet arrangement....

  13. DECOLORIZATION AND CHEMICAL REGENERATION OF ...

    African Journals Online (AJOL)

    Preferred Customer

    2006-09-26

    Received September 26, 2006; revised September 22, 2008). ABSTRACT. Citric acid fermentation (CAF) liquor decolorization by granular activated carbon (GAC) was studied and an improved chemical regeneration method of the exhausted ...

  14. Regenerable Contaminant Removal System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regenerable Contaminant Removal System (RCRS) is an innovative method to remove sulfur and halide compounds from contaminated gas streams to part-per-billion...

  15. DECOLORIZATION AND CHEMICAL REGENERATION OF ...

    African Journals Online (AJOL)

    GAC) was studied and an improved chemical regeneration method of the exhausted GAC by the color of CAF liquor was investigated. The effects of the GAC dosage, time and temperature on the decoloring efficiency (DE %) were studied.

  16. Engineering membranes for bone regeneration.

    Science.gov (United States)

    Caridade, Sofia Glória Ferreira; Mano, João Filipe Colardelle da Luz

    2017-09-13

    This review is focused on the use of membranes for the specific application of bone regeneration. The first section focuses on the relevance of membranes in this context and what are the specifications that they should possess in order to improve the regeneration of bone. Afterwards, several techniques to engineer bone membranes by using "bulk"-like methods are discussed where different parameters to induce bone formation are disclosed in a way to have desirable structural and functional properties. Subsequently, the production of nanostructured membranes using a bottom-up approach are discussed by highlighting the main advances in the field of bone regeneration. Primordial importance is given to the promotion of osteoconductive and osteoinductive capability during the membrane design. Whenever possible the films prepared using different techniques are compared in terms of handability, bone guiding ability, osteoinductivity, adequate mechanical properties or biodegradability. A last chapter contemplates membranes only composed by cells, disclosing their potential to regenerate bone.

  17. Phylogenetic and specificity studies of two-domain GNA-related lectins: generation of multispecificity through domain duplication and divergent evolution

    Science.gov (United States)

    Van Damme, Els J. M.; Nakamura-Tsuruta, Sachiko; Smith, David F.; Ongenaert, Maté; Winter, Harry C.; Rougé, Pierre; Goldstein, Irwin J.; Mo, Hanqing; Kominami, Junko; Culerrier, Raphaël; Barre, Annick; Hirabayashi, Jun; Peumans, Willy J.

    2007-01-01

    A re-investigation of the occurrence and taxonomic distribution of proteins built up of protomers consisting of two tandem arrayed domains equivalent to the GNA [Galanthus nivalis (snowdrop) agglutinin] revealed that these are widespread among monotyledonous plants. Phylogenetic analysis of the available sequences indicated that these proteins do not represent a monophylogenetic group but most probably result from multiple independent domain duplication/in tandem insertion events. To corroborate the relationship between inter-domain sequence divergence and the widening of specificity range, a detailed comparative analysis was made of the sequences and specificity of a set of two-domain GNA-related lectins. Glycan microarray analyses, frontal affinity chromatography and surface plasmon resonance measurements demonstrated that the two-domain GNA-related lectins acquired a marked diversity in carbohydrate-binding specificity that strikingly contrasts the canonical exclusive specificity of their single domain counterparts towards mannose. Moreover, it appears that most two-domain GNA-related lectins interact with both high mannose and complex N-glycans and that this dual specificity relies on the simultaneous presence of at least two different independently acting binding sites. The combined phylogenetic, specificity and structural data strongly suggest that plants used domain duplication followed by divergent evolution as a mechanism to generate multispecific lectins from a single mannose-binding domain. Taking into account that the shift in specificity of some binding sites from high mannose to complex type N-glycans implies that the two-domain GNA-related lectins are primarily directed against typical animal glycans, it is tempting to speculate that plants developed two-domain GNA-related lectins for defence purposes. PMID:17288538

  18. The evolution from asparagine or threonine to cysteine in position 146 contributes to generation of a more efficient and stable form of muscle creatine kinase in higher vertebrates.

    Science.gov (United States)

    Zhao, Tong-Jin; Liu, Yang; Chen, Zhao; Yan, Yong-Bin; Zhou, Hai-Meng

    2006-01-01

    Creatine kinase, a key enzyme in vertebrate excitable tissues that require large energy fluxes, catalyzes the reversible transfer of phosphate between adenosine triphosphate and creatine. Sequence alignment indicated that the 146th amino acid is cysteine in the muscle creatine kinase of higher vertebrates including Amphibia, Reptilia, Aves and Mammalia. In fishes, it is cysteine in Agnatha and Chondrichthyes, and asparagine or threonine in Osteichthyes, which is the ancestor of Amphibia, Reptilia, Aves and Mammalia. To explore the structural and functional role of this special residue, a series of site-directed mutants of rabbit muscle creatine kinase were constructed, including C146S, C146N, C146T, C146G, C146A, C146D and C146R. A detailed comparison was made between wild-type creatine kinase and the mutants in catalytic activity, physico-chemical properties and structural stability against thermal inactivation and guanidine hydrochloride denaturation. It was found that except for C146S, the mutants had relatively lower catalytic activity and structural stability than Wt-CK. Wt-CK and C146S were the most stable ones, followed by C146N and C146T, and then C146G and C146A, and C146D and C146R were the least stable mutants. These results suggested that the 146th residue plays a crucial role in maintaining the structural stability of creatine kinase, and that the evolution in this amino acid from asparagine or threonine to cysteine contributes to the generation of a more efficient and more stable form of creatine kinase in higher vertebrates.

  19. Piezoelectric materials for tissue regeneration: A review.

    Science.gov (United States)

    Rajabi, Amir Hossein; Jaffe, Michael; Arinzeh, Treena Livingston

    2015-09-01

    The discovery of piezoelectricity, endogenous electric fields and transmembrane potentials in biological tissues raised the question whether or not electric fields play an important role in cell function. It has kindled research and the development of technologies in emulating biological electricity for tissue regeneration. Promising effects of electrical stimulation on cell growth and differentiation and tissue growth has led to interest in using piezoelectric scaffolds for tissue repair. Piezoelectric materials can generate electrical activity when deformed. Hence, an external source to apply electrical stimulation or implantation of electrodes is not needed. Various piezoelectric materials have been employed for different tissue repair applications, particularly in bone repair, where charges induced by mechanical stress can enhance bone formation; and in neural tissue engineering, in which electric pulses can stimulate neurite directional outgrowth to fill gaps in nervous tissue injuries. In this review, a summary of piezoelectricity in different biological tissues, mechanisms through which electrical stimulation may affect cellular response, and recent advances in the fabrication and application of piezoelectric scaffolds will be discussed. The discovery of piezoelectricity, endogenous electric fields and transmembrane potentials in biological tissues has kindled research and the development of technologies using electrical stimulation for tissue regeneration. Piezoelectric materials generate electrical activity in response to deformations and allow for the delivery of an electrical stimulus without the need for an external power source. As a scaffold for tissue engineering, growing interest exists due to its potential of providing electrical stimulation to cells to promote tissue formation. In this review, we cover the discovery of piezoelectricity in biological tissues, its connection to streaming potentials, biological response to electrical stimulation and

  20. Approaches towards endogenous pancreatic regeneration.

    Science.gov (United States)

    Banerjee, Meenal; Kanitkar, Meghana; Bhonde, Ramesh R

    2005-01-01

    The phenomenon of pancreatic regeneration in mammals has been well documented. It has been shown that pancreatic tissue is able to regenerate in several species of mammal after surgical insult. This tissue is also known to have the potential to maintain or increase its beta-cell mass in response to metabolic demands during pregnancy and obesity. Since deficiency in beta-cell mass is the hallmark of most forms of diabetes, it is worthwhile understanding pancreatic regeneration in the context of this disease. With this view in mind, this article aims to discuss the potential use in clinical strategies of knowledge that we obtained from studies carried out in animal models of diabetes. Approaches to achieve this goal involve the use of biomolecules, adult stem cells and gene therapy. Various molecules, such as glucagon-like peptide-1, beta-cellulin, nicotinamide, gastrin, epidermal growth factor-1 and thyroid hormone, play major roles in the initiation of endogenous islet regeneration in diabetes. The most accepted hypothesis is that these molecules stimulate islet precursor cells to undergo neogenesis or to induce replication of existing beta-cells, emphasizing the importance of pancreas-resident stem/progenitor cells in islet regeneration. Moreover, the potential of adult stem cell population from bone marrow, umbilical cord blood, liver, spleen, or amniotic membrane, is also discussed with regard to their potential to induce pancreatic regeneration.

  1. Regenerable biocide delivery unit

    Science.gov (United States)

    Sauer, Richard L. (Inventor); Colombo, Gerald V. (Inventor); Jolly, Clifford D. (Inventor)

    1993-01-01

    A method and apparatus are disclosed for maintaining continuous, long-term microbial control in the water supply for potable, hygiene, and experimental water for space activities, as well as treatment of water supplies on Earth. The water purification is accomplished by introduction of molecular iodine into the water supply to impart a desired iodine residual. The water is passed through an iodinated anion exchange resin bed. The iodine is bound as I-(sub n) at the anion exchange sites and releases I(sub 2) into the water stream flowing through the bed. The concentration of I(sub 2) in the flowing water gradually decreases and, in the prior art, the ion-exchange bed has had to be replaced. In a preferred embodiment, a bed of iodine crystals is provided with connections for flowing water therethrough to produce a concentrated (substantially saturated) aqueous iodine solution which is passed through the iodinated resin bed to recharge the bed with bound iodine. The bed of iodine crystals is connected in parallel with the iodinated resin bed and is activated periodically (e.g., by timer, by measured flow of water, or by iodine residual level) to recharge the bed. Novelty resides in the capability of inexpensively and repeatedly regenerating the ion-exchange bed in situ.

  2. Mesenchymal stem cell-mediated functional tooth regeneration in swine.

    Science.gov (United States)

    Sonoyama, Wataru; Liu, Yi; Fang, Dianji; Yamaza, Takayoshi; Seo, Byoung-Moo; Zhang, Chunmei; Liu, He; Gronthos, Stan; Wang, Cun-Yu; Wang, Songlin; Shi, Songtao

    2006-12-20

    Mesenchymal stem cell-mediated tissue regeneration is a promising approach for regenerative medicine for a wide range of applications. Here we report a new population of stem cells isolated from the root apical papilla of human teeth (SCAP, stem cells from apical papilla). Using a minipig model, we transplanted both human SCAP and periodontal ligament stem cells (PDLSCs) to generate a root/periodontal complex capable of supporting a porcelain crown, resulting in normal tooth function. This work integrates a stem cell-mediated tissue regeneration strategy, engineered materials for structure, and current dental crown technologies. This hybridized tissue engineering approach led to recovery of tooth strength and appearance.

  3. Mesenchymal stem cell-mediated functional tooth regeneration in swine.

    Directory of Open Access Journals (Sweden)

    Wataru Sonoyama

    2006-12-01

    Full Text Available Mesenchymal stem cell-mediated tissue regeneration is a promising approach for regenerative medicine for a wide range of applications. Here we report a new population of stem cells isolated from the root apical papilla of human teeth (SCAP, stem cells from apical papilla. Using a minipig model, we transplanted both human SCAP and periodontal ligament stem cells (PDLSCs to generate a root/periodontal complex capable of supporting a porcelain crown, resulting in normal tooth function. This work integrates a stem cell-mediated tissue regeneration strategy, engineered materials for structure, and current dental crown technologies. This hybridized tissue engineering approach led to recovery of tooth strength and appearance.

  4. Genome-wide analysis of gene expression during Xenopus tropicalis tadpole tail regeneration

    Directory of Open Access Journals (Sweden)

    Love Nick R

    2011-11-01

    Full Text Available Abstract Background The molecular mechanisms governing vertebrate appendage regeneration remain poorly understood. Uncovering these mechanisms may lead to novel therapies aimed at alleviating human disfigurement and visible loss of function following injury. Here, we explore tadpole tail regeneration in Xenopus tropicalis, a diploid frog with a sequenced genome. Results We found that, like the traditionally used Xenopus laevis, the Xenopus tropicalis tadpole has the capacity to regenerate its tail following amputation, including its spinal cord, muscle, and major blood vessels. We examined gene expression using the Xenopus tropicalis Affymetrix genome array during three phases of regeneration, uncovering more than 1,000 genes that are significantly modulated during tail regeneration. Target validation, using RT-qPCR followed by gene ontology (GO analysis, revealed a dynamic regulation of genes involved in the inflammatory response, intracellular metabolism, and energy regulation. Meta-analyses of the array data and validation by RT-qPCR and in situ hybridization uncovered a subset of genes upregulated during the early and intermediate phases of regeneration that are involved in the generation of NADP/H, suggesting that these pathways may be important for proper tail regeneration. Conclusions The Xenopus tropicalis tadpole is a powerful model to elucidate the genetic mechanisms of vertebrate appendage regeneration. We have produced a novel and substantial microarray data set examining gene expression during vertebrate appendage regeneration.

  5. Carbon dioxide capture process with regenerable sorbents

    Science.gov (United States)

    Pennline, Henry W.; Hoffman, James S.

    2002-05-14

    A process to remove carbon dioxide from a gas stream using a cross-flow, or a moving-bed reactor. In the reactor the gas contacts an active material that is an alkali-metal compound, such as an alkali-metal carbonate, alkali-metal oxide, or alkali-metal hydroxide; or in the alternative, an alkaline-earth metal compound, such as an alkaline-earth metal carbonate, alkaline-earth metal oxide, or alkaline-earth metal hydroxide. The active material can be used by itself or supported on a substrate of carbon, alumina, silica, titania or aluminosilicate. When the active material is an alkali-metal compound, the carbon-dioxide reacts with the metal compound to generate bicarbonate. When the active material is an alkaline-earth metal, the carbon dioxide reacts with the metal compound to generate carbonate. Spent sorbent containing the bicarbonate or carbonate is moved to a second reactor where it is heated or treated with a reducing agent such as, natural gas, methane, carbon monoxide hydrogen, or a synthesis gas comprising of a combination of carbon monoxide and hydrogen. The heat or reducing agent releases carbon dioxide gas and regenerates the active material for use as the sorbent material in the first reactor. New sorbent may be added to the regenerated sorbent prior to subsequent passes in the carbon dioxide removal reactor.

  6. Motor Axonal Regeneration After Partial and Complete Spinal Cord Transection

    Science.gov (United States)

    Lu, Paul; Blesch, Armin; Graham, Lori; Wang, Yaozhi; Samara, Ramsey; Banos, Karla; Haringer, Verena; Havton, Leif; Weishaupt, Nina; Bennett, David; Fouad, Karim; Tuszynski, Mark H.

    2012-01-01

    We subjected rats to either partial mid-cervical or complete upper thoracic spinal cord transections and examined whether combinatorial treatments support motor axonal regeneration into and beyond the lesion. Subjects received cAMP injections into brainstem reticular motor neurons to stimulate their endogenous growth state, bone marrow stromal cell grafts in lesion sites to provide permissive matrices for axonal growth, and brain-derived neurotrophic factor (BDNF) gradients beyond the lesion to stimulate distal growth of motor axons. Findings were compared to several control groups. Combinatorial treatment generated motor axon regeneration beyond both C5 hemisection and complete transection sites. Yet despite formation of synapses with neurons below the lesion, motor outcomes worsened after partial cervical lesions and spasticity worsened after complete transection. These findings highlight the complexity of spinal cord repair, and the need for additional control and shaping of axonal regeneration. PMID:22699902

  7. Bone morphogenetic proteins: periodontal regeneration.

    Science.gov (United States)

    Rao, Subramaniam M; Ugale, Gauri M; Warad, Shivaraj B

    2013-03-01

    Periodontitis is an infectious inflammatory disease that results in attachment loss and bone loss. Regeneration of the periodontal tissues entails de novo formation of cementum, periodontal ligament, and alveolar bone. Several different approaches are currently being explored to achieve complete, reliable, and reproducible regeneration of periodontal tissues. The therapeutic management of new bone formation is one of the key issues in successful periodontal regeneration. Bone morphogenetic proteins form a unique group of proteins within the transforming growth factor superfamily of genes and have a vital role in the regulation in the bone induction and maintenance. The activity of bone morphogenetic proteins was first identified in the 1960s, but the proteins responsible for bone induction were unknown until the purification and cloning of human bone morphogenetic proteins in the 1980s, because of their osteoinductive potential. Bone morphogenetic proteins have gained a lot of interest as therapeutic agents for treating periodontal defects. A systematic search for data related to the use of bone morphogenetic proteins for the regeneration of periodontal defects was performed to recognize studies on animals and human (PUBMED, MEDLINE, COCHRANE, and Google search). All the studies included showed noticeable regeneration of periodontal tissues with the use of BMP.

  8. Mechanisms of urodele limb regeneration

    Science.gov (United States)

    2017-01-01

    Abstract This review explores the historical and current state of our knowledge about urodele limb regeneration. Topics discussed are (1) blastema formation by the proteolytic histolysis of limb tissues to release resident stem cells and mononucleate cells that undergo dedifferentiation, cell cycle entry and accumulation under the apical epidermal cap. (2) The origin, phenotypic memory, and positional memory of blastema cells. (3) The role played by macrophages in the early events of regeneration. (4) The role of neural and AEC factors and interaction between blastema cells in mitosis and distalization. (5) Models of pattern formation based on the results of axial reversal experiments, experiments on the regeneration of half and double half limbs, and experiments using retinoic acid to alter positional identity of blastema cells. (6) Possible mechanisms of distalization during normal and intercalary regeneration. (7) Is pattern formation is a self‐organizing property of the blastema or dictated by chemical signals from adjacent tissues? (8) What is the future for regenerating a human limb? PMID:29299322

  9. Gene expression following induction of regeneration in Drosophila wing imaginal discs. Expression profile of regenerating wing discs

    Directory of Open Access Journals (Sweden)

    Blanco Enrique

    2010-09-01

    Full Text Available Abstract Background Regeneration is the ability of an organism to rebuild a body part that has been damaged or amputated, and can be studied at the molecular level using model organisms. Drosophila imaginal discs, which are the larval primordia of adult cuticular structures, are capable of undergoing regenerative growth after transplantation and in vivo culture into the adult abdomen. Results Using expression profile analyses, we studied the regenerative behaviour of wing discs at 0, 24 and 72 hours after fragmentation and implantation into adult females. Based on expression level, we generated a catalogue of genes with putative role in wing disc regeneration, identifying four classes: 1 genes with differential expression within the first 24 hours; 2 genes with differential expression between 24 and 72 hours; 3 genes that changed significantly in expression levels between the two time periods; 4 genes with a sustained increase or decrease in their expression levels throughout regeneration. Among these genes, we identified members of the JNK and Notch signalling pathways and chromatin regulators. Through computational analysis, we recognized putative binding sites for transcription factors downstream of these pathways that are conserved in multiple Drosophilids, indicating a potential relationship between members of the different gene classes. Experimental data from genetic mutants provide evidence of a requirement of selected genes in wing disc regeneration. Conclusions We have been able to distinguish various classes of genes involved in early and late steps of the regeneration process. Our data suggests the integration of signalling pathways in the promoters of regulated genes.

  10. A Conserved MicroRNA Regulatory Circuit Is Differentially Controlled during Limb/Appendage Regeneration

    Science.gov (United States)

    King, Benjamin L.; Yin, Viravuth P.

    2016-01-01

    Background Although regenerative capacity is evident throughout the animal kingdom, it is not equally distributed throughout evolution. For instance, complex limb/appendage regeneration is muted in mammals but enhanced in amphibians and teleosts. The defining characteristic of limb/appendage regenerative systems is the formation of a dedifferentiated tissue, termed blastema, which serves as the progenitor reservoir for regenerating tissues. In order to identify a genetic signature that accompanies blastema formation, we employ next-generation sequencing to identify shared, differentially regulated mRNAs and noncoding RNAs in three different, highly regenerative animal systems: zebrafish caudal fins, bichir pectoral fins and axolotl forelimbs. Results These studies identified a core group of 5 microRNAs (miRNAs) that were commonly upregulated and 5 miRNAs that were commonly downregulated, as well as 4 novel tRNAs fragments with sequences conserved with humans. To understand the potential function of these miRNAs, we built a network of 1,550 commonly differentially expressed mRNAs that had functional relationships to 11 orthologous blastema-associated genes. As miR-21 was the most highly upregulated and most highly expressed miRNA in all three models, we validated the expression of known target genes, including the tumor suppressor, pdcd4, and TGFβ receptor subunit, tgfbr2 and novel putative target genes such as the anti-apoptotic factor, bcl2l13, Choline kinase alpha, chka and the regulator of G-protein signaling, rgs5. Conclusions Our extensive analysis of RNA-seq transcriptome profiling studies in three regenerative animal models, that diverged in evolution ~420 million years ago, reveals a common miRNA-regulated genetic network of blastema genes. These comparative studies extend our current understanding of limb/appendage regeneration by identifying previously unassociated blastema genes and the extensive regulation by miRNAs, which could serve as a foundation

  11. A leaf-based regeneration and transformation system for maize (Zea mays L.).

    Science.gov (United States)

    Ahmadabadi, Mohammad; Ruf, Stephanie; Bock, Ralph

    2007-08-01

    Efficient methods for in vitro propagation, regeneration, and transformation of plants are of pivotal importance to both basic and applied research. While being the world's major food crops, cereals are among the most difficult-to-handle plants in tissue culture which severely limits genetic engineering approaches. In maize, immature zygotic embryos provide the predominantly used material for establishing regeneration-competent cell or callus cultures for genetic transformation experiments. The procedures involved are demanding, laborious and time consuming and depend on greenhouse facilities. We have developed a novel tissue culture and plant regeneration system that uses maize leaf tissue and thus is independent of zygotic embryos and greenhouse facilities. We report here: (i) a protocol for the efficient induction of regeneration-competent callus from maize leaves in the dark, (ii) a protocol for inducing highly regenerable callus in the light, and (iii) the use of leaf-derived callus for the generation of stably transformed maize plants.

  12. Post-autotomy regeneration of respiratory trees in the holothurian Apostichopus japonicus (Holothuroidea, Aspidochirotida).

    Science.gov (United States)

    Dolmatov, Igor Y; Ginanova, Talia T

    2009-04-01

    Specialised respiratory organs, viz. the respiratory trees attached to the dorsal part of the cloaca, are present in most holothurians. These organs evolved within the class Holothuroidea and are absent in other echinoderms. Some holothurian species can regenerate their respiratory trees but others lack this ability. Respiratory trees therefore provide a model for investigating the origin and evolution of repair mechanisms in animals. We conducted a detailed morphological study of the regeneration of respiratory trees after their evisceration in the holothurian Apostichopus japonicus. Regeneration of the respiratory trees occurred rapidly and, on the 15th day after evisceration, their length reached 15-20 mm. Repair involved cells of the coelomic and luminal epithelia of the cloaca. Peritoneocytes and myoepithelial cells behaved differently during regeneration: the peritoneocytes kept their intercellular junctions and migrated as a united layer, whereas groups of myoepithelial cells disaggregated and migrated as individual cells. Although myoepithelial cells did not divide during regeneration, the peritoneocytes proliferated actively. The contractile system of the respiratory trees was assumed to develop during regeneration by the migration of myoepithelial cells from the coelomic epithelium of the cloaca. The luminal epithelium of the respiratory trees formed as a result of dedifferentiation, migration and transformation of cells of the cloaca lining. The mode of regeneration of holothurian respiratory trees is discussed.

  13. Hospitality, culture and regeneration: urban decay, entrepreneurship and the "ruin" bars of Budapest.

    Science.gov (United States)

    Lugosi, Peter; Bell, David; Lugosi, Krisztina

    2010-01-01

    This paper considers the relationships between hospitality, culture and urban regeneration through an examination of rom (ruin) venues, which operate in dilapidated buildings in Budapest, Hungary. The paper reviews previous work on culture and urban regeneration in order to locate the role of hospitality within emerging debates. It subsequently interrogates the evolution of the rom phenomenon and demonstrates how, in this context, hospitality thrives because of social and physical decay in urban locations, how operators and entrepreneurs exploit conflicts among various actors involved in regeneration and how hospitality may be mobilised purposefully in the regeneration process. The paper demonstrates how networked entrepreneurship maintains these operations and how various forms of cultural production are entangled and mobilised in the venues' hospitality propositions.

  14. THE HISTORY AND ENDURING CONTRIBUTIONS OF PLANARIANS TO THE STUDY OF ANIMAL REGENERATION

    Science.gov (United States)

    Elliott, Sarah A.; Sánchez Alvarado, Alejandro

    2012-01-01

    Having an almost unlimited capacity to regenerate tissues lost to age and injury, planarians have long fascinated naturalists. In the Western hemisphere alone, their documented history spans more than 200 years. Planarians were described in the early 19th century as being “immortal under the edge of the knife,” and initial investigation of these remarkable animals was significantly influenced by studies of regeneration in other organisms and from the flourishing field of experimental embryology in the late 19th and early 20th centuries. This review strives to place the study of planarian regeneration into a broader historical context by focusing on the significance and evolution of knowledge in this field. It also synthesizes our current molecular understanding of the mechanisms of planarian regeneration uncovered since this animal’s relatively recent entrance into the molecular-genetic age. PMID:23799578

  15. QPSK regeneration without active phase-locking

    DEFF Research Database (Denmark)

    Kjøller, Niels-Kristian; Da Ros, Francesco; Røge, Kasper Meldgaard

    2016-01-01

    QPSK regeneration without active phase stabilization is investigated in numerical simulations. We propose an improved scheme for phase-locking free QPSK regeneration showing significant improvements in the error vector magnitude of the signal....

  16. Economics and policy environments for forest regeneration.

    Science.gov (United States)

    Donald F. Flora

    1970-01-01

    MOST OF YOUR DAILY CONCERNS IN FOREST REGENERATION are biologic, technologic, and mechanical. But periodically, perhaps once a year, many of you must consider regeneration in a context that includes alternative uses for the financial resources you have.

  17. Fingernails Yield Clues to Limb Regeneration

    Science.gov (United States)

    ... Spotlight on Research Fingernails Yield Clues to Limb Regeneration By Kirstie Saltsman, Ph.D. | January 5, 2014 ... Diseases has uncovered chemical signals that drive the regeneration of lost digit tips in mice. The findings, ...

  18. Nanostructured Mesoporous Silicas for Bone Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    Isabel Izquierdo-Barba

    2008-01-01

    Full Text Available The research on the development of new biomaterials that promote bone tissue regeneration is receiving great interest by the biomedical scientific community. Recent advances in nanotechnology have allowed the design of materials with nanostructure similar to that of natural bone. These materials can promote new bone formation by inducing the formation of nanocrystalline apatites analogous to the mineral phase of natural bone onto their surfaces, i.e. they are bioactive. They also stimulate osteoblast proliferation and differentiation and, therefore, accelerate the healing processes. Silica-based ordered mesoporous materials are excellent candidates to be used as third generation bioceramics that enable the adsorption and local control release of biological active agents that promote bone regeneration. This local delivery capability together with the bioactive behavior of mesoporous silicas opens up promising expectations in the bioclinical field. In this review, the last advances in nanochemistry aimed at designing and tailoring the chemical and textural properties of mesoporous silicas for biomedical applications are described. The recent developed strategies to synthesize bioactive glasses with ordered mesopore arrangements are also summarized. Finally, a deep discussion about the influence of the textural parameters and organic modification of mesoporous silicas on molecules adsorption and controlled release is performed.

  19. "Restoratively driven papilla regeneration: correcting the dreaded 'black triangle'".

    Science.gov (United States)

    Clark, David

    2008-11-01

    Until now there were very few dedicated tools or techniques for restoratively driven papilla regeneration. Previous attempts at both diastema closure and papilla regeneration using direct composites often ended with significant compromise in periodontal health. The interdental papilla serves as both an esthetic and functional asset, and anatomically ideal interproximal composite shapes can serve as a predictable scaffold to regain this valuable gingival architecture. The reader is strongly cautioned that to attempt this elective procedure using no magnification and without appropriate materials may not be in the patient's best interest, and that non treatment or referral is recommended. This extremely rounded, injection molded composite filling technique is new. Once again, technological advancements allow changes to perform techniques that were previously unthinkable. Slowly, the profession will change their thought patterns, retrain their hands and minds, and allow this substantial clinical evolution in restorative dentistry.

  20. Generation 1.5 Preservice Teachers: The Evolution of Their Writing Confidence Levels and Self-Efficacy in Writing Intensive Courses

    Science.gov (United States)

    Lewis, Katie D.

    2016-01-01

    This action research examines how Generation 1.5 preservice teachers develop as writers during writing intensive courses. Generation 1.5 reflects immigrants who have life experiences inclusive of two or more countries including diverse cultures and languages (Roberge, 2009). Understanding the factors impacting how Generation 1.5 students use…

  1. Effect and mechanism of microwave-activated ultraviolet-advanced oxidation technology for adsorbent regeneration.

    Science.gov (United States)

    Sun, Yanlong; Zheng, Tong; Zhang, Guangshan; Zheng, Yunli; Wang, Peng

    2017-10-15

    To decrease the secondary pollution of volatile organic compounds (VOCs) during adsorbent regeneration by microwave, electrodeless lamp was added in the microwave field to oxidize VOCs in the gas phase. Ultraviolet has a significant improvement on mineralization of VOCs generated from adsorbate during adsorbent regeneration. However, the mechanism and main influence factors on the degradation of VOCs are not clear. The effect of microwave power, regeneration time, airflow rate, and humidity content on the mineralization of adsorbed tetracycline during adsorbent regeneration was studied. Ozone concentration and ultraviolet irradiation intensity were also measured to analyze the mechanism of the microwave-ultraviolet adsorbent regeneration method. Although the electrodeless lamp adsorbed microwave and competed with the regenerated adsorbent, the mineralization percentage of tetracycline increased about 10% with the presence of electrodeless lamp at the same microwave power supply. Besides, humidity content also takes an important role on enhancing the mineralization of tetracycline. The mineralization of tetracycline in the microwave-ultraviolet field consists of three major parts: pyrolysis, ozone oxidation, and free radical oxidation. More than 50% adsorbed tetracycline can be oxidized into H2O and CO2 during regeneration in 5 min. These results support the potential use of electrodeless lamp to treat VOCs in the gas phase to decrease the risk of secondary pollution during adsorbent regeneration.

  2. Regeneration of southern hardwoods: some ecological concepts

    Science.gov (United States)

    David L. Loftis

    1989-01-01

    Classical concepts of post-disturbance succession through well-defined seral stages to a well-defined ,climax stage( s) are not a useful conceptual framework for predicting species composition of regeneration resulting from the application of regeneration treatments in complex southern hardwood forests. Hardwood regeneration can be better understood, and more useful...

  3. Semiconductor devices for all-optical regeneration

    DEFF Research Database (Denmark)

    Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne

    2003-01-01

    We review different implementations of semiconductor devices for all-optical regeneration. A general model will be presented for all-optical regeneration in fiber links, taking into consideration the trade-off between non-linearity and noise. Furthermore we discuss a novel regenerator type, based...

  4. All optical regeneration using semiconductor devices

    DEFF Research Database (Denmark)

    Mørk, Jesper; Öhman, Filip; Tromborg, Bjarne

    All-optical regeneration is a key functionality for implementing all-optical networks. We present a simple theory for the bit-error-rate in links employing all-optical regenerators, which elucidates the interplay between the noise and and nonlinearity of the regenerator. A novel device structure ...... is analyzed, emphasizing general aspects of active semiconductor waveguides....

  5. An experimental study of passive regenerator geometries

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Nielsen, Kaspar Kirstein; Pryds, Nini

    2011-01-01

    experimental uncertainty associated with magnetocaloric material properties, all regenerators are made of aluminum. The performance of corrugated plates and dimpled plates are compared to traditional flat plate regenerators for a range of cycle times and utilizations. Each regenerator is built using 18...

  6. MECHANICAL REGENERATION OF SAND WASTE

    Directory of Open Access Journals (Sweden)

    D. I. Gnir

    2005-01-01

    Full Text Available The experimental activation of the sand regenerator of the firm SINTO is carried out at ОАО “MZOO". It is shown that sand grains are cleared from films of binding agents, that allows to use the treated sand for preparation of agglutinant and core sands.

  7. Bone regeneration during distraction osteogenesis

    NARCIS (Netherlands)

    Amir, L.R.; Everts, V.; Bronckers, A.L.J.J.

    2009-01-01

    Bone has the capacity to regenerate in response to injury. During distraction osteogenesis, the renewal of bone is enhanced by gradual stretching of the soft connec- tive tissues in the gap area between two separated bone segments. This procedure has received much clinical atten- tion as a way to

  8. Skeletal muscle development and regeneration.

    NARCIS (Netherlands)

    Grefte, S.; Kuijpers-Jagtman, A.M.; Torensma, R.; Hoff, J.W. Von den

    2007-01-01

    In the late stages of muscle development, a unique cell population emerges that is a key player in postnatal muscle growth and muscle regeneration. The location of these cells next to the muscle fibers triggers their designation as satellite cells. During the healing of injured muscle tissue,

  9. Nonwoven scaffolds for bone regeneration

    OpenAIRE

    Durham, Elaine R.; Tronci, Giuseppe; Yang,Xuebin; Wood, David J.; Russell, Stephen J.

    2016-01-01

    Developing successful scaffolds requires clinicians to adopt a multidisciplinary approach in order to understand and stimulate the natural bone regeneration process. A variety of natural and synthetic biomaterials, including naturally extracted, chemically functionalised collagen and synthetic Poly(epsilon-caprolactone) (PCL), can be manufactured into fibres, enabling the formation of nonwoven scaffolds. Many different nonwoven architectures and structural features can then be introduced, dep...

  10. Gene therapy for tissue regeneration.

    Science.gov (United States)

    Cutroneo, Kenneth R

    2003-02-01

    Tissue repair and regeneration are the normal biological responses of many different tissues in the body to injury. During the healing process, profound changes occur in cell composition and extracellular matrix (ECM) formation. Fibroblasts and equivalent reparative cells migrate to the wounded area and subsequently proliferate. These cells and reparative cells from the surrounding tissue are responsible for the rapid repair which results in tissue regeneration. Growth factors, one of which is transforming growth factor-beta (TGF-beta), stimulate fibroblasts and smooth muscle cells to proliferate and synthesize ECM proteins. This process of early repair provides a rapid way to restore new tissue and mechanical integrity. This early tissue repair process is normally followed by involution, which requires the production and activation of proteases, tissue maturation and remodeling, reorganization and finally regeneration. Alternately, failure to replace the critical components of the ECM, including elastin and basement membrane, results in abnormal regeneration of the epithelial cell layer. Although remodeling should occur during healing, provisional repair may be followed by excessive synthesis and deposition of collagen, which results in irreversible fibrosis and scarring. This excessive fibrosis which occurs in aberrant healing is at least in part mediated by persistent TGF-beta. Because of the central role of collagen in the wound healing process, the pharmacological control of collagen synthesis has been of paramount importance as a possible way to abrogate aberrant healing and prevent irreversible fibrosis. Fibrosis is an abnormal response to tissue injury. Copyright 2002 Wiley-Liss, Inc.

  11. Mechanical device for tissue regeneration

    NARCIS (Netherlands)

    Herder, J.L.; Maij, E.

    2010-01-01

    The invention relates to a mechanical device for tissue- regeneration inside a patient, comprising means (2, 3) to place a scaffold for the tissue under mechanical stress. Said means comprise a first device-part (2) and a second device-part (3) which parts are arranged to be movable with respect to

  12. Penentuan Kesetimbangan Adsorpsi Regenerated Spent Bleaching Earth (RSBE) terhadap Ion Cu(II)

    OpenAIRE

    s, Andi Muhammad; ', Yusnimar '; Helianty, Sri '

    2015-01-01

    Spent bleaching earth (SBE) is the waste that generated from bleaching units in palm oil refining industry. Solution for the waste reduction is regenerating SBE into regenerated spent bleaching earth (RSBE) which can be used as adsorbent heavy metals in waste waters such as Cu(II) derived from the industry. In this study SBE regenerated by extracting oil soxhletation at 72oC for 8 hours with solvent n-hexane, then washed with 3% HCl and finally physically activated at a temperature of 470oC. ...

  13. Tissue engineering for skeletal muscle regeneration.

    Science.gov (United States)

    Rizzi, Roberto; Bearzi, Claudia; Mauretti, Arianna; Bernardini, Sergio; Cannata, Stefano; Gargioli, Cesare

    2012-07-01

    Stem cells and regenerative medicine have obtained a remarkable consent from the scientific community for their promising ability to recover aged, injured and diseased tissue. However, despite the noteworthy potential, hurdles currently hinder their use and clinical application: cell survival, immune response, tissue engraftment and efficient differentiation. Hence a new interdisciplinary scientific approach, such as tissue engineering, is going deep attempts to mimic neo-tissue-genesis as well as stem cell engraftment amelioration. Skeletal muscle tissue engineering represents a great potentiality in medicine for muscle regeneration exploiting new generation injectable hydrogel as scaffold supporting progenitor/stem cells for muscle differentiation reconstructing the natural skeletal muscle tissue architecture influenced by matrix mechanical and physical property and by a dynamic environment.

  14. Plants regenerated from tissue culture contain stable epigenome changes in rice.

    Science.gov (United States)

    Stroud, Hume; Ding, Bo; Simon, Stacey A; Feng, Suhua; Bellizzi, Maria; Pellegrini, Matteo; Wang, Guo-Liang; Meyers, Blake C; Jacobsen, Steven E

    2013-03-19

    Most transgenic crops are produced through tissue culture. The impact of utilizing such methods on the plant epigenome is poorly understood. Here we generated whole-genome, single-nucleotide resolution maps of DNA methylation in several regenerated rice lines. We found that all tested regenerated plants had significant losses of methylation compared to non-regenerated plants. Loss of methylation was largely stable across generations, and certain sites in the genome were particularly susceptible to loss of methylation. Loss of methylation at promoters was associated with deregulated expression of protein-coding genes. Analyses of callus and untransformed plants regenerated from callus indicated that loss of methylation is stochastically induced at the tissue culture step. These changes in methylation may explain a component of somaclonal variation, a phenomenon in which plants derived from tissue culture manifest phenotypic variability. DOI:http://dx.doi.org/10.7554/eLife.00354.001.

  15. Lead-cooled hybrid reactors and fuel regeneration for energy production and incineration evolution of physical parameters and induced radiotoxicity; Capacites des reacteurs hybrides au plomb pour la production d'energie et l'incineration avec multirecyclage des combustibles evolution des parametres physiques radiotoxicites induites

    Energy Technology Data Exchange (ETDEWEB)

    David, S

    1999-07-01

    The concept of accelerator driven subcritical reactors (hybrid reactors), as re-launched in the beginning of the 1990's by C. Rubbia and C.D. Bowman, allows to open new paths in the management of radioactive wastes. This work treats, first, of the study of the neutron multiplication characteristics in a subcritical reactor core and shows the fundamental differences with critical systems and the advantages that follow. This study is based on the series of measurements performed at Cadarache (Muse experiment), the first results of which are presented. The subcritical property of an hybrid reactor makes this system very flexible and allows to foresee different uses, like the energy production or the incineration of wastes. The second part of this work deals with the Monte Carlo simulation of the capacities of fast spectrum and lead-cooled hybrid systems to produce energy by using different fuel cycles (uranium and thorium), and in the same time regenerating the fissile matter and keeping the reactivity up without any external intervention. Different types of fuel multi-recycles are considered. The results allow to quantify the advantages linked with the use of the thorium cycle, in particular in terms of radiotoxicity abatement. The study of the intermediate steps necessary to develop this reactor technology with the present day fuels (plutonium from thermal reactors and enriched uranium) proposes an efficient management of the actinides produced by today's reactors which are used as auxiliary fissile materials. Finally, the incineration of actinides at the end of the cycle (shutdown scenario) is considered and allows to describe the advantage of lead-cooled hybrid systems for the abatement of the radiotoxicity of an inventory at the end of cycle. (J.S.)

  16. The Evolution of the Stem Cell Theory for Heart Failure.

    Science.gov (United States)

    Silvestre, Jean-Sébastien; Menasché, Philippe

    2015-12-01

    Various stem cell-based approaches for cardiac repair have achieved encouraging results in animal experiments, often leading to their rapid proceeding to clinical testing. However, freewheeling evolutionary developments of the stem cell theory might lead to dystopian scenarios where heterogeneous sources of therapeutic cells could promote mixed clinical outcomes in un-stratified patient populations. This review focuses on the lessons that should be learnt from the first generation of stem cell-based strategies and emphasizes the absolute requirement to better understand the basic mechanisms of stem cell biology and cardiogenesis. We will also discuss about the unexpected "big bang" in the stem cell theory, "blasting" the therapeutic cells to their unchallenged ability to release paracrine factors such as extracellular membrane vesicles. Paradoxically, the natural evolution of the stem cell theory for cardiac regeneration may end with the development of cell-free strategies with multiple cellular targets including cardiomyocytes but also other infiltrating or resident cardiac cells.

  17. Limb Regeneration in Xenopus laevis Froglet

    Directory of Open Access Journals (Sweden)

    Makoto Suzuki

    2006-01-01

    Full Text Available Limb regeneration in amphibians is a representative process of epimorphosis. This type of organ regeneration, in which a mass of undifferentiated cells referred to as the “blastema” proliferate to restore the lost part of the amputated organ, is distinct from morphallaxis as observed, for instance, in Hydra, in which rearrangement of pre-existing cells and tissues mainly contribute to regeneration. In contrast to complete limb regeneration in urodele amphibians, limb regeneration in Xenopus, an anuran amphibian, is restricted. In this review of some aspects regarding adult limb regeneration in Xenopus laevis, we suggest that limb regeneration in adult Xenopus, which is pattern/tissue deficient, also represents epimorphosis.

  18. Mesenchymal Stem Cell-Mediated Functional Tooth Regeneration in Swine

    OpenAIRE

    Wataru Sonoyama; Yi Liu; Dianji Fang; Takayoshi Yamaza; Byoung-Moo Seo; Chunmei Zhang; He Liu; Stan Gronthos; Cun-Yu Wang; Songlin Wang; Songtao Shi

    2006-01-01

    Mesenchymal stem cell-mediated tissue regeneration is a promising approach for regenerative medicine for a wide range of applications. Here we report a new population of stem cells isolated from the root apical papilla of human teeth (SCAP, stem cells from apical papilla). Using a minipig model, we transplanted both human SCAP and periodontal ligament stem cells (PDLSCs) to generate a root/periodontal complex capable of supporting a porcelain crown, resulting in normal tooth function. This wo...

  19. Quantum mechanical evolution operator in the presence of a scalar linear potential: discussion on the evolved state, phase shift generator and tunneling

    Science.gov (United States)

    Fratini, F.; Safari, L.

    2014-08-01

    We discuss the form of the wave-function of a state subjected to a scalar linear potential, focusing on quantum tunneling. We analyze the phases acquired by the evolved state and show that some are of a pure quantum mechanical origin. We propose a simple experimental scenario to measure one of these phases. We apply the evolution equations to re-analyze the Stern and Gerlach experiment and to demonstrate how to manipulate spin by employing constant electric fields.

  20. Regeneration of the radial nerve cord in the sea cucumber Holothuria glaberrima

    Directory of Open Access Journals (Sweden)

    García-Arrarás José E

    2009-01-01

    Full Text Available Abstract Background Regeneration of neurons and fibers in the mammalian spinal cord has not been plausible, even though extensive studies have been made to understand the restrictive factors involved. New experimental models and strategies are necessary to determine how new nerve cells are generated and how fibers regrow and connect with their targets in adult animals. Non-vertebrate deuterostomes might provide some answers to these questions. Echinoderms, with their amazing regenerative capacities could serve as model systems; however, very few studies have been done to study the regeneration of their nervous system. Results We have studied nerve cord regeneration in the echinoderm Holothuria glaberrima. These are sea cucumbers or holothurians members of the class Holothuroidea. One radial nerve cord, part of the echinoderm CNS, was completely transected using a scalpel blade. Animals were allowed to heal for up to four weeks (2, 6, 12, 20, and 28 days post-injury before sacrificed. Tissues were sectioned in a cryostat and changes in the radial nerve cord were analyzed using classical dyes and immmuohistochemistry. In addition, the temporal and spatial distribution of cell proliferation and apoptosis was assayed using BrdU incorporation and the TUNEL assay, respectively. We found that H. glaberrima can regenerate its radial nerve cord within a month following transection. The regenerated cord looks amazingly similar in overall morphology and cellular composition to the uninjured cord. The cellular events associated to radial cord regeneration include: (1 outgrowth of nerve fibers from the injured radial cord stumps, (2 intense cellular division in the cord stumps and in the regenerating radial nerve cords, (3 high levels of apoptosis in the RNC adjacent to the injury and within the regenerating cord and (4 an increase in the number of spherule-containing cells. These events are similar to those that occur in other body wall tissues during wound

  1. The regeneration capacity of the flatworm Macrostomum lignano--on repeated regeneration, rejuvenation, and the minimal size needed for regeneration.

    Science.gov (United States)

    Egger, B; Ladurner, P; Nimeth, K; Gschwentner, R; Rieger, R

    2006-10-01

    The lion's share of studies on regeneration in Plathelminthes (flatworms) has been so far carried out on a derived taxon of rhabditophorans, the freshwater planarians (Tricladida), and has shown this group's outstanding regeneration capabilities in detail. Sharing a likely totipotent stem cell system, many other flatworm taxa are capable of regeneration as well. In this paper, we present the regeneration capacity of Macrostomum lignano, a representative of the Macrostomorpha, the basal-most taxon of rhabditophoran flatworms and one of the most basal extant bilaterian protostomes. Amputated or incised transversally, obliquely, and longitudinally at various cutting levels, M. lignano is able to regenerate the anterior-most body part (the rostrum) and any part posterior of the pharynx, but cannot regenerate a head. Repeated regeneration was observed for 29 successive amputations over a period of almost 12 months. Besides adults, also first-day hatchlings and older juveniles were shown to regenerate after transversal cutting. The minimum number of cells required for regeneration in adults (with a total of 25,000 cells) is 4,000, including 160 neoblasts. In hatchlings only 1,500 cells, including 50 neoblasts, are needed for regeneration. The life span of untreated M. lignano was determined to be about 10 months.

  2. The regeneration capacity of the flatworm Macrostomum lignano—on repeated regeneration, rejuvenation, and the minimal size needed for regeneration

    Science.gov (United States)

    Ladurner, P.; Nimeth, K.; Gschwentner, R.; Rieger, R.

    2006-01-01

    The lion’s share of studies on regeneration in Plathelminthes (flatworms) has been so far carried out on a derived taxon of rhabditophorans, the freshwater planarians (Tricladida), and has shown this group’s outstanding regeneration capabilities in detail. Sharing a likely totipotent stem cell system, many other flatworm taxa are capable of regeneration as well. In this paper, we present the regeneration capacity of Macrostomum lignano, a representative of the Macrostomorpha, the basal-most taxon of rhabditophoran flatworms and one of the most basal extant bilaterian protostomes. Amputated or incised transversally, obliquely, and longitudinally at various cutting levels, M. lignano is able to regenerate the anterior-most body part (the rostrum) and any part posterior of the pharynx, but cannot regenerate a head. Repeated regeneration was observed for 29 successive amputations over a period of almost 12 months. Besides adults, also first-day hatchlings and older juveniles were shown to regenerate after transversal cutting. The minimum number of cells required for regeneration in adults (with a total of 25,000 cells) is 4,000, including 160 neoblasts. In hatchlings only 1,500 cells, including 50 neoblasts, are needed for regeneration. The life span of untreated M. lignano was determined to be about 10 months. PMID:16604349

  3. Analysis of newly established EST databases reveals similarities between heart regeneration in newt and fish

    Directory of Open Access Journals (Sweden)

    Weis Patrick

    2010-01-01

    Full Text Available Abstract Background The newt Notophthalmus viridescens possesses the remarkable ability to respond to cardiac damage by formation of new myocardial tissue. Surprisingly little is known about changes in gene activities that occur during the course of regeneration. To begin to decipher the molecular processes, that underlie restoration of functional cardiac tissue, we generated an EST database from regenerating newt hearts and compared the transcriptional profile of selected candidates with genes deregulated during zebrafish heart regeneration. Results A cDNA library of 100,000 cDNA clones was generated from newt hearts 14 days after ventricular injury. Sequencing of 11520 cDNA clones resulted in 2894 assembled contigs. BLAST searches revealed 1695 sequences with potential homology to sequences from the NCBI database. BLAST searches to TrEMBL and Swiss-Prot databases assigned 1116 proteins to Gene Ontology terms. We also identified a relatively large set of 174 ORFs, which are likely to be unique for urodele amphibians. Expression analysis of newt-zebrafish homologues confirmed the deregulation of selected genes during heart regeneration. Sequences, BLAST results and GO annotations were visualized in a relational web based database followed by grouping of identified proteins into clusters of GO Terms. Comparison of data from regenerating zebrafish hearts identified biological processes, which were uniformly overrepresented during cardiac regeneration in newt and zebrafish. Conclusion We concluded that heart regeneration in newts and zebrafish led to the activation of similar sets of genes, which suggests that heart regeneration in both species might follow similar principles. The design of the newly established newt EST database allows identification of molecular pathways important for heart regeneration.

  4. Regeneration of the exocrine pancreas is delayed in telomere-dysfunctional mice.

    Directory of Open Access Journals (Sweden)

    Guido von Figura

    Full Text Available INTRODUCTION: Telomere shortening is a cell-intrinsic mechanism that limits cell proliferation by induction of DNA damage responses resulting either in apoptosis or cellular senescence. Shortening of telomeres has been shown to occur during human aging and in chronic diseases that accelerate cell turnover, such as chronic hepatitis. Telomere shortening can limit organ homeostasis and regeneration in response to injury. Whether the same holds true for pancreas regeneration in response to injury is not known. METHODS: In the present study, pancreatic regeneration after acute cerulein-induced pancreatitis was studied in late generation telomerase knockout mice with short telomeres compared to telomerase wild-type mice with long telomeres. RESULTS: Late generation telomerase knockout mice exhibited impaired exocrine pancreatic regeneration after acute pancreatitis as seen by persistence of metaplastic acinar cells and markedly reduced proliferation. The expression levels of p53 and p21 were not significantly increased in regenerating pancreas of late generation telomerase knockout mice compared to wild-type mice. CONCLUSION: Our results indicate that pancreatic regeneration is limited in the context of telomere dysfunction without evidence for p53 checkpoint activation.

  5. Muscle regeneration in mitochondrial myopathies

    DEFF Research Database (Denmark)

    Krag, T O; Hauerslev, S; Jeppesen, T D

    2013-01-01

    Mitochondrial myopathies cover a diverse group of disorders in which ragged red and COX-negative fibers are common findings on muscle morphology. In contrast, muscle degeneration and regeneration, typically found in muscular dystrophies, are not considered characteristic features of mitochondrial...... by a dystrophic morphology. The results add to the complexity of the pathogenesis underlying mitochondrial myopathies, and expand the knowledge about the impact of energy deficiency on another aspect of muscle structure and function....

  6. Ultrahigh-Temperature Regeneration of Long Period Gratings (LPGs in Boron-Codoped Germanosilicate Optical Fibre

    Directory of Open Access Journals (Sweden)

    Wen Liu

    2015-08-01

    Full Text Available The regeneration of UV-written long period gratings (LPG in boron-codoped germanosilicate “W” fibre is demonstrated and studied. They survive temperatures over 1000 °C. Compared with regenerated FBGs fabricated in the same type of fibre, the evolution curves of LPGs during regeneration and post-annealing reveal even more detail of glass relaxation. Piece-wise temperature dependence is observed, indicating the onset of a phase transition of glass in the core and inner cladding at ~500 °C and ~250 °C, and the melting of inner cladding between 860 °C and 900 °C. An asymmetric spectral response with increasing and decreasing annealing temperature points to the complex process dependent material system response. Resonant wavelength tuning by adjusting the dwell temperature at which regeneration is undertaken is demonstrated, showing a shorter resonant wavelength and shorter time for stabilisation with higher dwell temperatures. All the regenerated LPGs are nearly strain-insensitive and cannot be tuned by applying loads during annealing as done for regenerated FBGs.

  7. The effect of endogenous hydrogen peroxide induced by cold treatment in the improvement of tissue regeneration efficiency

    NARCIS (Netherlands)

    Szechynska-Hebda, M.; Skrzypek, E.; Dabrowska, G.; Wedzony, M.; Lammeren, van A.A.M.

    2012-01-01

    We propose that oxidative stress resulting from an imbalance between generation and scavenging hydrogen peroxide contributes to tissue regeneration efficiency during somatic embryogenesis of hexaploid winter wheat (Triticum aestivum cv. Kamila) and organogenesis of faba bean (Vicia faba ssp. minor

  8. Tissue-engineered bone regeneration.

    Science.gov (United States)

    Petite, H; Viateau, V; Bensaïd, W; Meunier, A; de Pollak, C; Bourguignon, M; Oudina, K; Sedel, L; Guillemin, G

    2000-09-01

    Bone lesions above a critical size become scarred rather than regenerated, leading to nonunion. We have attempted to obtain a greater degree of regeneration by using a resorbable scaffold with regeneration-competent cells to recreate an embryonic environment in injured adult tissues, and thus improve clinical outcome. We have used a combination of a coral scaffold with in vitro-expanded marrow stromal cells (MSC) to increase osteogenesis more than that obtained with the scaffold alone or the scaffold plus fresh bone marrow. The efficiency of the various combinations was assessed in a large segmental defect model in sheep. The tissue-engineered artificial bone underwent morphogenesis leading to complete recorticalization and the formation of a medullary canal with mature lamellar cortical bone in the most favorable cases. Clinical union never occurred when the defects were left empty or filled with the scaffold alone. In contrast, clinical union was obtained in three out of seven operated limbs when the defects were filled with the tissue-engineered bone.

  9. MHD (Magnetohydrodynamics) recovery and regeneration

    Energy Technology Data Exchange (ETDEWEB)

    McIlroy, R. A. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Probert, P. B. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Lahoda, E. J. [Westinghouse Electric Corp., Pittsburgh, PA (United States); Swift, W. M. [Argonne National Lab. (ANL), Argonne, IL (United States); Jackson, D. M. [Univ. of Tennessee Space Inst. (UTSI), Tullahoma, TN (United States); Prasad, J. [Univ. of Tennessee Space Inst. (UTSI), Tullahoma, TN (United States); Martin, J. [Hudson Engineering (United States); Rogers, C. [Hudson Engineering (United States); Ho, K. K. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Senary, M. K. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Lee, S. [Univ. of Akron, OH (United States)

    1988-10-01

    A two-phase program investigating MHD seed regeneration is described. In Phase I, bench scale experiments were carried out to demonstrate the technical feasibility of a proposed Seed Regeneration Process. The Phase I data has been used for the preliminary design of a Proof-of-Concept (POC) plant which will be built and tested in Phase II. The Phase I data will also be used to estimate the costs of a 300 Mw(t) demonstration plant for comparison with other processes. The Seed Regeneration Process consists of two major subprocesses; a Westinghouse Dry Reduction process and a modified Tampella (sulfur) Recovery process. The Westinghouse process reduces the recovered spent seed (i.e., potassium sulfate) to potassium polysulfide in a rotary kiln. The reduction product is dissolved in water to form green liquor, clarified to remove residual coal ash, and sent to the Tampella sulfur release system. The sulfur is released using carbon dioxide from flue gas in a two stage reaction. The sulfur is converted to elemental sulfur as a marketable by product. The potassium is crystallized from the green liquor and dried to the anhydrous form for return to the MHD unit.

  10. Zebrafish heart regeneration: 15 years of discoveries

    Science.gov (United States)

    González‐Rosa, Juan Manuel; Burns, Caroline E.

    2017-01-01

    Abstract Cardiovascular disease is the leading cause of death worldwide. Compared to other organs such as the liver, the adult human heart lacks the capacity to regenerate on a macroscopic scale after injury. As a result, myocardial infarctions are responsible for approximately half of all cardiovascular related deaths. In contrast, the zebrafish heart regenerates efficiently upon injury through robust myocardial proliferation. Therefore, deciphering the mechanisms that underlie the zebrafish heart's endogenous regenerative capacity represents an exciting avenue to identify novel therapeutic strategies for inducing regeneration of the human heart. This review provides a historical overview of adult zebrafish heart regeneration. We summarize 15 years of research, with a special focus on recent developments from this fascinating field. We discuss experimental findings that address fundamental questions of regeneration research. What is the origin of regenerated muscle? How is regeneration controlled from a genetic and molecular perspective? How do different cell types interact to achieve organ regeneration? Understanding natural models of heart regeneration will bring us closer to answering the ultimate question: how can we stimulate myocardial regeneration in humans? PMID:28979788

  11. Electric fish: new insights into conserved processes of adult tissue regeneration.

    Science.gov (United States)

    Unguez, Graciela A

    2013-07-01

    Biology is replete with examples of regeneration, the process that allows animals to replace or repair cells, tissues and organs. As on land, vertebrates in aquatic environments experience the occurrence of injury with varying frequency and to different degrees. Studies demonstrate that ray-finned fishes possess a very high capacity to regenerate different tissues and organs when they are adults. Among fishes that exhibit robust regenerative capacities are the neotropical electric fishes of South America (Teleostei: Gymnotiformes). Specifically, adult gymnotiform electric fishes can regenerate injured brain and spinal cord tissues and restore amputated body parts repeatedly. We have begun to identify some aspects of the cellular and molecular mechanisms of tail regeneration in the weakly electric fish Sternopygus macrurus (long-tailed knifefish) with a focus on regeneration of skeletal muscle and the muscle-derived electric organ. Application of in vivo microinjection techniques and generation of myogenic stem cell markers are beginning to overcome some of the challenges owing to the limitations of working with non-genetic animal models with extensive regenerative capacity. This review highlights some aspects of tail regeneration in S. macrurus and discusses the advantages of using gymnotiform electric fishes to investigate the cellular and molecular mechanisms that produce new cells during regeneration in adult vertebrates.

  12. Loss of Mgat5a-mediated N-glycosylation stimulates regeneration in zebrafish.

    Science.gov (United States)

    Pei, Wuhong; Huang, Sunny C; Xu, Lisha; Pettie, Kade; Ceci, María Laura; Sánchez, Mario; Allende, Miguel L; Burgess, Shawn M

    2016-01-01

    We are using genetics to identify genes specifically involved in hearing regeneration. In a large-scale genetic screening, we identified mgat5a, a gene in the N-glycosylation biosynthesis pathway whose activity negatively impacts hair cell regeneration. We used a combination of mutant analysis in zebrafish and a hair cell regeneration assay to phenotype the loss of Mgat5a activity in zebrafish. We used pharmacological inhibition of N-glycosylation by swansonine. We also used over-expression analysis by mRNA injections to demonstrate how changes in N-glycosylation can alter cell signaling. We found that mgat5a was expressed in multiple tissues during zebrafish embryo development, particularly enriched in neural tissues including the brain, retina, and lateral line neuromasts. An mgat5a insertional mutation and a CRISPR/Cas9-generated truncation mutation both caused an enhancement of hair cell regeneration which could be phenocopied by pharmacological inhibition with swansonine. In addition to hair cell regeneration, inhibition of the N-glycosylation pathway also enhanced the regeneration of lateral line axon and caudal fins. Further analysis showed that N-glycosylation altered the responsiveness of TGF-beta signaling. The findings from this study provide experimental evidence for the involvement of N-glycosylation in tissue regeneration and cell signaling.

  13. Urodele limb and tail regeneration in early biological thought: an essay on scientific controversy and social change.

    Science.gov (United States)

    Dinsmore, C E

    1996-08-01

    Lazzaro Spallanzani (1729-1799) announced his discoveries of salamander tail and limb regeneration to Charles Bonnet (1729-1793) in the 1760's. The phenomenon soon became embroiled with the ongoing epigenesis/preformation controversy over the fundamental nature of generation. The concept of animal regeneration as a process linked to reproduction had emerged in 1740 with Abraham Trembley's (1710-1783) demonstration that a bisected hydra gives rise to two new, completely formed individuals. The discovery of urodele appendage regeneration revealed for the first time that a quadruped could regenerate and restore complex form, lizard tail regenerates having been recognized as only substitute structures. Moreover, regeneration of a quadruped appendage became problematic because it was not supposed to be possible and because it conflicted with prevailing opinion about the nature of higher organisms. Why animal regeneration in general engendered conflict transcends biological concerns and touches on personal philosophical commitments. Preformation had been adopted into orthodox theology as a validation of predestination and of the hierarchical structuring of man's relationships to nature and within society. Epigenetic interpretations of regeneration represented challenges to certain aspects of the extant social and political fabric in their extrapolation to ideas of what constituted natural order. Urodele regeneration as an integral part of the epigenesis/preformation debate therefore constituted a formative component of eighteenth century thought in a period of social and intellectual revolution.

  14. Thought Evolution

    Directory of Open Access Journals (Sweden)

    Shadrikov V.D.

    2015-08-01

    Full Text Available The thought evolution is studied by historical reconstruction method that is based on the propositions of the theory of culturalhistorical determination of the psyche development, and the data of the morphological analysis and child development, and the conception of the psyche neuroontogenesis. The grounds for advisability of protothinking are presented. The protothinking is understood as the use of objective thought in cases of awareness absence. It is shown that protothinking is a form of transition from animal thinking to human speech. The particular attention is paid to the process of the word producing and thought generation in that process. The conditions of word producing as cooccurring acoustic pattern served for though expression are discussed. It is emphasized that a word is produced by a particular person. The historical development of the language and the specificity of this development are pointed out

  15. Composite cell sheet for periodontal regeneration: crosstalk between different types of MSCs in cell sheet facilitates complex periodontal-like tissue regeneration.

    Science.gov (United States)

    Zhang, Hao; Liu, Shiyu; Zhu, Bin; Xu, Qiu; Ding, Yin; Jin, Yan

    2016-11-14

    Tissue-engineering strategies based on mesenchymal stem cells (MSCs) and cell sheets have been widely used for periodontal tissue regeneration. However, given the complexity in periodontal structure, the regeneration methods using a single species of MSC could not fulfill the requirement for periodontal regeneration. We researched the interaction between the periodontal ligament stem cells (PDLSCs) and jaw bone marrow-derived mesenchymal stem cells (JBMMSCs), and constructed a composite cell sheet comprising both of the above MSCs to regenerate complex periodontium-like structures in nude mice. Our results show that by co-culturing PDLSCs and JBMMSCs, the expressions of bone and extracellular matrix (ECM)-related genes and proteins were significantly improved in both MSCs. Further investigations showed that, compared to the cell sheet using PDLSCs or JBMMSCs, the composite stem cell sheet (CSCS), which comprises these two MSCs, expressed higher levels of bone- and ECM-related genes and proteins, and generated a composite structure more similar to the native periodontal tissue physiologically in vivo. In conclusion, our results demonstrate that the crosstalk between PDLSCs and JBMMSCs in cell sheets facilitate regeneration of complex periodontium-like structures, providing a promising new strategy for physiological and functional regeneration of periodontal tissue.

  16. Storage, generation, and use of hydrogen

    Science.gov (United States)

    McClaine, Andrew W.; Rolfe, Jonathan L.; Larsen, Christopher A.; Konduri, Ravi K.

    2006-05-30

    A composition comprising a carrier liquid; a dispersant; and a chemical hydride. The composition can be used in a hydrogen generator to generate hydrogen for use, e.g., as a fuel. A regenerator recovers elemental metal from byproducts of the hydrogen generation process.

  17. Dendrite Injury Triggers DLK-Independent Regeneration

    Directory of Open Access Journals (Sweden)

    Michelle C. Stone

    2014-01-01

    Full Text Available Axon injury triggers regeneration through activation of a conserved kinase cascade, which includes the dual leucine zipper kinase (DLK. Although dendrites are damaged during stroke, traumatic brain injury, and seizure, it is not known whether mature neurons monitor dendrite injury and initiate regeneration. We probed the response to dendrite damage using model Drosophila neurons. Two larval neuron types regrew dendrites in distinct ways after all dendrites were removed. Dendrite regeneration was also triggered by injury in adults. Next, we tested whether dendrite injury was initiated with the same machinery as axon injury. Surprisingly, DLK, JNK, and fos were dispensable for dendrite regeneration. Moreover, this MAP kinase pathway was not activated by injury to dendrites. Thus, neurons respond to dendrite damage and initiate regeneration without using the conserved DLK cascade that triggers axon regeneration.

  18. The Cellular Basis for Animal Regeneration

    OpenAIRE

    Tanaka, Elly M.; Reddien, Peter W.

    2011-01-01

    The ability of animals to regenerate missing parts is a dramatic and poorly understood aspect of biology. The sources of new cells for these regenerative phenomena have been sought for decades. Recent advances involving cell fate tracking in complex tissues have shed new light on the cellular underpinnings of regeneration in Hydra, planarians, zebrafish, Xenopus, and Axolotl. Planarians accomplish regeneration with use of adult pluripotent stem cells, whereas several vertebrates utilize a col...

  19. A quantitative metabolomics peek into planarian regeneration.

    Science.gov (United States)

    Natarajan, Nivedita; Ramakrishnan, Padma; Lakshmanan, Vairavan; Palakodeti, Dasaradhi; Rangiah, Kannan

    2015-05-21

    The fresh water planarian species Schmidtea mediterranea is an emerging stem cell model because of its capability to regenerate a whole animal from a small piece of tissue. It is one of the best model systems to address the basic mechanisms essential for regeneration. Here, we are interested in studying the roles of various amines, thiols and nucleotides in planarian regeneration, stem cell function and growth. We developed mass spectrometry based quantitative methods and validated the differential enrichment of 35 amines, 7 thiol metabolites and 4 nucleotides from both intact and regenerating planarians. Among the amines, alanine in sexual and asparagine in asexual are the highest (>1000 ng/mg) in the intact planarians. The levels of thiols such as cysteine and GSH are 651 and 1107 ng mg(-1) in planarians. Among the nucleotides, the level of cGMP is the lowest (0.03 ng mg(-1)) and the level of AMP is the highest (187 ng mg(-1)) in both of the planarian strains. We also noticed increasing levels of amines in both anterior and posterior regenerating planarians. The blastema from day 3 regenerating planarians also showed higher amounts of many amines. Interestingly, the thiol (cysteine and GSH) levels are well maintained during planarian regeneration. This suggests an inherent and effective mechanism to control induced oxidative stress because of the robust regeneration and stem cell proliferation. Like in intact planarians, the level of cGMP is also very low in regenerating planarians. Surprisingly, the levels of amines and thiols in head regenerating blastemas are ∼3 times higher compared to those for tail regenerating blastemas. Thus our results strongly indicate the potential roles of amines, thiols and nucleotides in planarian regeneration.

  20. Fanning the flames to regenerate the heart

    OpenAIRE

    Riley, Paul R.

    2014-01-01

    Damage to the adult mammalian heart is irreversible, and lost cells are not replaced through regeneration. In neonatal mice, prior to P7, heart tissue can be regenerated after injury; however, the factors that facilitate cardiac regeneration in the neonatal heart are not known. In this issue of the JCI, Aurora and colleagues evaluated the immune response following myocardial infarction in P1 mice compared with that in P14 mice, which have lost their regenerative capacity, and identified a pop...

  1. Regeneration of phenolic antioxidants from phenoxyl radicals: An ESR and electrochemical study of antioxidant hierarchy

    DEFF Research Database (Denmark)

    Jørgensen, Lars V.; Madsen, Helle L.; Thomsen, Marianne K.

    1999-01-01

    Radicals from the flavonoids quercetin, (+)-catechin, (+/-)-taxifolin and luteolin, and from all-rac-alpha-tocopherol have been generated electrochemically by one-electron oxidation in deaerated dimethylformamide (DMF), and characterised by electron spin resonance spectroscopy (ESR) after spin...... antioxidants from their oxidation products with a regeneration index (defined as moles regenerated of the oxidised phenolic antioxidant divided with moles of all-rac-alpha-tucopherol consumed) of 0.90 +/- 0.16 for quercetin, 0.48 +/- 0.11 for (+)-catechin, 0.48 +/- 0.06 for (+/-)-taxifolin and 0.50 +/- 0.......10 for luteolin in equi molar 1.00 mM solution. Quercetin was found to have the highest regeneration Quercetin was found to have the highest regeneration index among the flavonoids: 0.88 +/- 0.13 for (+)-catechin, 0.41 +/- 0.03 for (+/-)-taxifolin and 0.41 +/- 0.02 for luteolin. The antioxidant hierarchy based...

  2. Effectiveness of high temperature innovative geometry fixed ceramic matrix regenerators used in glass furnaces

    Directory of Open Access Journals (Sweden)

    Wołkowycki Grzegorz

    2016-03-01

    Full Text Available The paper presents the effectiveness of waste heat recovery regenerators equipped with innovative ceramic matrix forming an integral part of a real glass furnace. The paper full description of the regenerators’ matrix structure with its dimensions, thermo-physical properties and operating parameters is included experimentally determined was the effectiveness of the regenerators has been descrbed using the obtained experimental data such as the operating temperature, gas flows as well as the gases generated during the liquid glass manufacturing process. The effectiveness values refer not only to the heating cycle when the regenerator matrix is heated by combustion gases but also to the cooling cycle in which the matrix is cooled as a result of changes in the direction of the flowing gas. On the basis of the determined effectiveness values for both cycles and measurement uncertainties it was possible, to calculate the weighted average efficiency for each of the regenerators.

  3. The planarian flatworm: an in vivo model for stem cell biology and nervous system regeneration

    Science.gov (United States)

    Gentile, Luca; Cebrià, Francesc; Bartscherer, Kerstin

    2011-01-01

    Planarian flatworms are an exception among bilaterians in that they possess a large pool of adult stem cells that enables them to promptly regenerate any part of their body, including the brain. Although known for two centuries for their remarkable regenerative capabilities, planarians have only recently emerged as an attractive model for studying regeneration and stem cell biology. This revival is due in part to the availability of a sequenced genome and the development of new technologies, such as RNA interference and next-generation sequencing, which facilitate studies of planarian regeneration at the molecular level. Here, we highlight why planarians are an exciting tool in the study of regeneration and its underlying stem cell biology in vivo, and discuss the potential promises and current limitations of this model organism for stem cell research and regenerative medicine. PMID:21135057

  4. The planarian flatworm: an in vivo model for stem cell biology and nervous system regeneration

    Directory of Open Access Journals (Sweden)

    Luca Gentile

    2011-01-01

    Full Text Available Planarian flatworms are an exception among bilaterians in that they possess a large pool of adult stem cells that enables them to promptly regenerate any part of their body, including the brain. Although known for two centuries for their remarkable regenerative capabilities, planarians have only recently emerged as an attractive model for studying regeneration and stem cell biology. This revival is due in part to the availability of a sequenced genome and the development of new technologies, such as RNA interference and next-generation sequencing, which facilitate studies of planarian regeneration at the molecular level. Here, we highlight why planarians are an exciting tool in the study of regeneration and its underlying stem cell biology in vivo, and discuss the potential promises and current limitations of this model organism for stem cell research and regenerative medicine.

  5. The cellular basis for animal regeneration

    Science.gov (United States)

    Tanaka, Elly; Reddien, Peter W.

    2011-01-01

    The ability of animals to regenerate missing parts is a dramatic and poorly understood aspect of biology. The sources of new cells for these regenerative phenomena have been sought for decades. Recent advances involving cell fate tracking in complex tissues have shed new light on the cellular underpinnings of regeneration in Hydra, planarians, zebrafish, Xenopus, and Axolotl. Planarians accomplish regeneration with use of adult pluripotent stem cells, whereas several vertebrates utilize a collection of lineage-restricted progenitors from different tissues. Together, an array of cellular strategies—from pluripotent stem cells to tissue-specific stem cells and dedifferentiation—are utilized for regeneration. PMID:21763617

  6. Emerin increase in regenerating muscle fibers

    Directory of Open Access Journals (Sweden)

    S Squarzoni

    2009-06-01

    Full Text Available The fate of emerin during skeletal muscle regeneration was investigated in an animal model by means of crush injury. Immunofluorescence, immunoblotting and mRNA analysis demonstrated that emerin level is increased in regenerating rat muscle fibers with respect to normal mature myofibers. This finding suggests an involvement of emerin during the muscle fiber regeneration process, in analogy with its reported involvement in muscle cell differentiation in vitro. The impairment of skeletal muscle physiological regeneration or reorganization could be a possible pathogenetic mechanism for Emery Dreifuss muscular dystrophy.

  7. Angiogenesis is inhibitory for mammalian digit regeneration

    Science.gov (United States)

    Yu, Ling; Yan, Mingquan; Simkin, Jennifer; Ketcham, Paulina D.; Leininger, Eric; Han, Manjong

    2014-01-01

    Abstract The regenerating mouse digit tip is a unique model for investigating blastema formation and epimorphic regeneration in mammals. The blastema is characteristically avascular and we previously reported that blastema expression of a known anti‐angiogenic factor gene, Pedf, correlated with a successful regenerative response (Yu, L., Han, M., Yan, M., Lee, E. C., Lee, J. & Muneoka, K. (2010). BMP signaling induces digit regeneration in neonatal mice. Development, 137, 551–559). Here we show that during regeneration Vegfa transcripts are not detected in the blastema but are expressed at the onset of differentiation. Treating the amputation wound with vascular endothelial growth factor enhances angiogenesis but inhibits regeneration. We next tested bone morphogenetic protein 9 (BMP9), another known mediator of angiogenesis, and found that BMP9 is also a potent inhibitor of digit tip regeneration. BMP9 induces Vegfa expression in the digit stump suggesting that regenerative failure is mediated by enhanced angiogenesis. Finally, we show that BMP9 inhibition of regeneration is completely rescued by treatment with pigment epithelium‐derived factor. These studies show that precocious angiogenesis is inhibitory for regeneration, and provide compelling evidence that the regulation of angiogenesis is a critical factor in designing therapies aimed at stimulating mammalian regeneration. PMID:27499862

  8. Regeneration in the Era of Functional Genomics and Gene Network Analysis

    Science.gov (United States)

    Smith, Joel; Morgan, Jennifer R.; Zottoli, Steven J.; Smith, Peter J.; Buxbaum, Joseph D.; Bloom, Ona E.

    2014-01-01

    What gives an organism the ability to regrow tissues and to recover function where another organism fails is the central problem of regenerative biology. The challenge is to describe the mechanisms of regeneration at the molecular level, delivering detailed insights into the many components that are cross-regulated. In other words, a broad, yet deep dissection of the system-wide network of molecular interactions is needed. Functional genomics has been used to elucidate gene regulatory networks (GRNs) in developing tissues, which, like regeneration, are complex systems. Therefore, we reason that the GRN approach, aided by next generation technologies, can also be applied to study the molecular mechanisms underlying the complex functions of regeneration. We ask what characteristics a model system must have to support a GRN analysis. Our discussion focuses on regeneration in the central nervous system, where loss of function has particularly devastating consequences for an organism. We examine a cohort of cells conserved across all vertebrates, the reticulospinal (RS) neurons, which lend themselves well to experimental manipulations. In the lamprey, a jawless vertebrate, there are giant RS neurons whose large size and ability to regenerate make them particularly suited for a GRN analysis. Adding to their value, a distinct subset of lamprey RS neurons reproducibly fail to regenerate, presenting an opportunity for side-by-side comparison of gene networks that promote or inhibit regeneration. Thus, determining the GRN for regeneration in RS neurons will provide a mechanistic understanding of the fundamental cues that lead to success or failure to regenerate. PMID:21876108

  9. A second generation genetic map of the bumblebee Bombus terrestris (Linnaeus, 1758 reveals slow genome and chromosome evolution in the Apidae

    Directory of Open Access Journals (Sweden)

    Kube Michael

    2011-01-01

    Full Text Available Abstract Background The bumblebee Bombus terrestris is an ecologically and economically important pollinator and has become an important biological model system. To study fundamental evolutionary questions at the genomic level, a high resolution genetic linkage map is an essential tool for analyses ranging from quantitative trait loci (QTL mapping to genome assembly and comparative genomics. We here present a saturated linkage map and match it with the Apis mellifera genome using homologous markers. This genome-wide comparison allows insights into structural conservations and rearrangements and thus the evolution on a chromosomal level. Results The high density linkage map covers ~ 93% of the B. terrestris genome on 18 linkage groups (LGs and has a length of 2'047 cM with an average marker distance of 4.02 cM. Based on a genome size of ~ 430 Mb, the recombination rate estimate is 4.76 cM/Mb. Sequence homologies of 242 homologous markers allowed to match 15 B. terrestris with A. mellifera LGs, five of them as composites. Comparing marker orders between both genomes we detect over 14% of the genome to be organized in synteny and 21% in rearranged blocks on the same homologous LG. Conclusions This study demonstrates that, despite the very high recombination rates of both A. mellifera and B. terrestris and a long divergence time of about 100 million years, the genomes' genetic architecture is highly conserved. This reflects a slow genome evolution in these bees. We show that data on genome organization and conserved molecular markers can be used as a powerful tool for comparative genomics and evolutionary studies, opening up new avenues of research in the Apidae.

  10. Signals and Cells Involved in Regulating Liver Regeneration

    Directory of Open Access Journals (Sweden)

    Liang-I. Kang

    2012-12-01

    Full Text Available Liver regeneration is a complex phenomenon aimed at maintaining a constant liver mass in the event of injury resulting in loss of hepatic parenchyma. Partial hepatectomy is followed by a series of events involving multiple signaling pathways controlled by mitogenic growth factors (HGF, EGF and their receptors (MET and EGFR. In addition multiple cytokines and other signaling molecules contribute to the orchestration of a signal which drives hepatocytes into DNA synthesis. The other cell types of the liver receive and transmit to hepatocytes complex signals so that, in the end of the regenerative process, complete hepatic tissue is assembled and regeneration is terminated at the proper time and at the right liver size. If hepatocytes fail to participate in this process, the biliary compartment is mobilized to generate populations of progenitor cells which transdifferentiate into hepatocytes and restore liver size.

  11. The Amount of Regenerated Heat Inside the Regenerator of a Stirling Engine

    Directory of Open Access Journals (Sweden)

    J. Škorpík

    2008-01-01

    Full Text Available The paper deals with analytical computing of the regenerated heat inside the regenerator of a Stirling engine. The total sum of the regenerated heat is constructed as a function of the crank angle in the case of Schmidt’s idealization. 

  12. Bone regeneration and stem cells

    DEFF Research Database (Denmark)

    Arvidson, K; Abdallah, B M; Applegate, L A

    2011-01-01

    This invited review covers research areas of central importance for orthopedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and fetal stem cells, effects of sex steroids on mesenchymal stem...... cells, use of platelet rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed....

  13. Internal waves on the upstream side of a large sill of the Mascarene Ridge: a comprehensive view of their generation mechanisms and evolution

    Science.gov (United States)

    da Silva, J. C. B.; Buijsman, M. C.; Magalhaes, J. M.

    2015-05-01

    In this paper we aim to clarify the generation of Internal Solitary Waves (ISWs) at work to the east of the Mascarene Plateau (Indian Ocean) using Synthetic Aperture Radar (SAR) imagery and MITgcm fully nonlinear and nonhydrostatic simulations. Realistic representations of stratification and bathymetry are used with asymmetric tidal forcing (including the steady South Equatorial Current which is assumed barotropic in the model) along a 2D transect aligned with the propagation direction of the wave signatures identified in the SAR. The combined flow (i.e. steady and tidal currents) is subcritical with respect to first-mode Internal Waves (IWs), but supercritical with respect to higher wave modes. Different types of nonlinear wave trains with distinct origins (i.e. tidal phase and location) have been identified with the combined aid of model and SAR: (1) large-scale primary mode-1 ISWs evolve from the disintegration of a multimodal baroclinic structure that appears on the upstream side of the sill; (2) mode-2 ISW-like waves that evolve from this same baroclinic structure and are arrested over the sill before being released upstream at the change of flow condition; (3) a large mode-2 lee wave is generated downstream of the sill (i.e. on the west side), which is trapped there during maximum westward tidal flow and released upstream when the tide relaxes; and (4) mode-2 ISW-like waves whose length-scales are O (20 km) appear some 50 km upstream of the sill, after an Internal Tide (IT) beam scatters into the pycnocline, itself originating from critical topography on the leeward (i.e. westward) side of the sill. The underwater sill being investigated is in the mixed-tidal-lee wave regime, where the internal tide release mechanism, lee wave generation and IT beams can coexist. The large-scale mode-2 ISW-like waves that form far upstream from the sill are long-lived features and can be identified in the SAR due to associated short-scale mode-1 ISWs which propagate with the

  14. A first-generation microsatellite-based genetic linkage map of the Siberian jay (Perisoreus infaustus: insights into avian genome evolution

    Directory of Open Access Journals (Sweden)

    Merilä Juha

    2009-01-01

    Full Text Available Abstract Background Genomic resources for the majority of free-living vertebrates of ecological and evolutionary importance are scarce. Therefore, linkage maps with high-density genome coverage are needed for progress in genomics of wild species. The Siberian jay (Perisoreus infaustus; Corvidae is a passerine bird which has been subject to lots of research in the areas of ecology and evolutionary biology. Knowledge of its genome structure and organization is required to advance our understanding of the genetic basis of ecologically important traits in this species, as well as to provide insights into avian genome evolution. Results We describe the first genetic linkage map of Siberian jay constructed using 117 microsatellites and a mapping pedigree of 349 animals representing five families from a natural population breeding in western Finland from the years 1975 to 2006. Markers were resolved into nine autosomal and a Z-chromosome-specific linkage group, 10 markers remaining unlinked. The best-position map with the most likely positions of all significantly linked loci had a total sex-average size of 862.8 cM, with an average interval distance of 9.69 cM. The female map covered 988.4 cM, whereas the male map covered only 774 cM. The Z-chromosome linkage group comprised six markers, three pseudoautosomal and three sex-specific loci, and spanned 10.6 cM in females and 48.9 cM in males. Eighty-one of the mapped loci could be ordered on a framework map with odds of >1000:1 covering a total size of 809.6 cM in females and 694.2 cM in males. Significant sex specific distortions towards reduced male recombination rates were revealed in the entire best-position map as well as within two autosomal linkage groups. Comparative mapping between Siberian jay and chicken anchored 22 homologous loci on 6 different linkage groups corresponding to chicken chromosomes Gga1, 2, 3, 4, 5, and Z. Quite a few cases of intra-chromosomal rearrangements within the

  15. Photokinesis and Djopsin gene expression analysis during the regeneration of planarian eyes.

    Science.gov (United States)

    Dong, Zimei; Yuwen, Yanqing; Sima, Yingxu; Dong, Yanping; Zhan, Huina; Chen, Guangwen; Liu, Dezeng

    2017-03-01

    Planarians provide the ideal model for studying eye development, with their simple eye structure and exceptionally rapid regeneration. Here, we observed the eye morphogenesis, photophobic behavior, spectral sensitivity and expression pattern of Djopsin in the freshwater planarian Dugesia japonica. The results showed that: (i) Djopsin encoding the putative protein belonged to the rhabdomeric opsins group and displayed high conservation during animal evolution; (ii) planarians displayed diverse photophobic response to different visible wavelengths and were more sensitive to light blue (495 nm) and yellow (635 nm); (iii) the morphogenesis and functional recovery of eyes were related to the expression pattern of Djopsin during head regeneration; and (iv) Djopsin gene plays a major role in functional recovery during eye regeneration and visual system maintenance in adult planarians. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  16. Peripheral Nerve Injuries and Transplantation of Olfactory Ensheathing Cells for Axonal Regeneration and Remyelination: Fact or Fiction?

    Directory of Open Access Journals (Sweden)

    Christine Radtke

    2012-10-01

    Full Text Available Successful nerve regeneration after nerve trauma is not only important for the restoration of motor and sensory functions, but also to reduce the potential for abnormal sensory impulse generation that can occur following neuroma formation. Satisfying functional results after severe lesions are difficult to achieve and the development of interventional methods to achieve optimal functional recovery after peripheral nerve injury is of increasing clinical interest. Olfactory ensheathing cells (OECs have been used to improve axonal regeneration and functional outcome in a number of studies in spinal cord injury models. The rationale is that the OECs may provide trophic support and a permissive environment for axonal regeneration. The experimental transplantation of OECs to support and enhance peripheral nerve regeneration is much more limited. This chapter reviews studies using OECs as an experimental cell therapy to improve peripheral nerve regeneration.

  17. Regeneration and transformation of Crambe abyssinica.

    Science.gov (United States)

    Qi, Weicong; Tinnenbroek-Capel, Iris E M; Schaart, Jan G; Huang, Bangquan; Cheng, Jihua; Visser, Richard G F; Van Loo, Eibertus N; Krens, Frans A

    2014-09-03

    Crambe abyssinica (crambe) is a non-food oil seed crop. Its seed oil is widely used in the chemical industry because of the high erucic acid content. Furthermore, it is a potential platform for various feedstock oils for industrial uses based on genetic modification. Here, we describe the development of a series of protocols for all steps required in the process of generating genetically modified crambe. Different explant types from crambe seedlings were tested for shoot regeneration using different hormone-combinations. Cotyledonary nodes on basic medium with 0.5 μM NAA and 2.2 μM BAP gave the highest regeneration percentages. For propagation by tissue culture, explants of stems, petioles, leaves and axillary buds of in vitro plantlets were tested using the optimized medium. Axillary buds showed the highest shoot proliferation efficiency. Cotyledonary nodes were used to test the proper concentration of kanamycin for selection of transformation events, and 10 to 25 mg · L(-1) were identified as effective. The cotyledonary nodes and cotyledons from 7-day-old seedlings were used in Agrobacterium-mediated transformations with two kinds of selection strategies, shifting or consistent. Using the shifting selection method (10 mg · L(-1) kanamycin, 25 mg · L(-1), then back to 10 mg · L(-1)) cotyledonary nodes gave 10% transformation frequency, and cotyledons 4%, while with the consistent method (25 mg · L(-1)) lower frequencies were found, 1% for cotyledonary nodes and 0% for cotyledons). Later, in vitro plant axillary buds were tried as explants for transformation, however, transformation frequency was low ranging from 0.5 to 2%. Overall, testing six different vectors and two kinds of Agrobacterium strains, the average transformation frequency using the shifting method was 4.4%. Determining T-DNA insertion numbers by Southern blotting showed that approximately 50% of the transgenic lines had a single-copy insertion. Present research revealed the potential of using

  18. Axon Regeneration Requires A Conserved MAP Kinase Pathway

    OpenAIRE

    Hammarlund, Marc; Nix, Paola; Hauth, Linda; Jorgensen, Erik M.; Bastiani, Michael

    2009-01-01

    Regeneration of injured neurons can restore function, but most neurons regenerate poorly or not at all. The failure to regenerate in some cases is due to a lack of activation of cell-intrinsic regeneration pathways. Thus, these pathways might be targeted for the development of therapies that can restore neuron function after injury or disease. Here, we show that the DLK-1 MAP kinase pathway is essential for regeneration in C. elegans motor neurons. Loss of this pathway eliminates regeneration...

  19. Liver Development, Regeneration, and Carcinogenesis

    Directory of Open Access Journals (Sweden)

    Janet W. C. Kung

    2010-01-01

    Full Text Available The identification of putative liver stem cells has brought closer the previously separate fields of liver development, regeneration, and carcinogenesis. Significant overlaps in the regulation of these processes are now being described. For example, studies in embryonic liver development have already provided the basis for directed differentiation of human embryonic stem cells and induced pluripotent stem cells into hepatocyte-like cells. As a result, the understanding of the cell biology of proliferation and differentiation in the liver has been improved. This knowledge can be used to improve the function of hepatocyte-like cells for drug testing, bioartificial livers, and transplantation. In parallel, the mechanisms regulating cancer cell biology are now clearer, providing fertile soil for novel therapeutic approaches. Recognition of the relationships between development, regeneration, and carcinogenesis, and the increasing evidence for the role of stem cells in all of these areas, has sparked fresh enthusiasm in understanding the underlying molecular mechanisms and has led to new targeted therapies for liver cirrhosis and primary liver cancers.

  20. Regeneration of Pelargonium in vitro

    Directory of Open Access Journals (Sweden)

    Agnieszka Wojtania

    2013-12-01

    Full Text Available Pelargonium sp. has been a subject of numerous studies to deterimine the effec tiveness of in vitro techniques to produce a large number of pathogen-free plants. Regeneration of pelargonium plants from the different initial explants as well via organogenesis as via somatic embryogenesis has been obtained. The most effective adventitious shoot formation has been achieved from shoot tips and axillary buds using cytokinin or cytokinin/auxin combinations. Leaf explants, whose general have lower organogenic potency, regenerate better in the presence of thidiazuron. This growth regulator stimulate the somatic embryos production from hypocotyl and cotyledone explants too. The main problem in tissue culture propagation of Pelargonium has been the high tendency to formation of vigorously growing callus with low organogenic potency and rapid senescence of cultures. Moreover, the significant differen ces in requirements to the medium composition (minerals, organic compounds and growth regulators between Pelargonium cultivars has been observed. This makes difficult to develop an universaI method of Pelargonium micropropagation.

  1. Continuing Climate Warming Will Result in Failure of Post-Harvest Natural Regeneration across the Landscape in Interior Alaska

    Science.gov (United States)

    Morimoto, M.; Juday, G. P.; Huettmann, F.

    2016-12-01

    Following forest disturbance, the stand initiation stage decisively influences future forest structure. Understanding post-harvest regeneration, especially under climate change, is essential to predicting future carbon stores in this extensive forest biome. We apply IPCC B1, A1B, and A2 climate scenarios to generate plausible future forest conditions under different management. We recorded presence of white spruce, birch, and aspen in 726 plots on 30 state forest white spruce harvest units. We built spatially explicit models and scenarios of species presence/absence using TreeNet (Stochastic Gradient Boosting). Post-harvest tree regeneration predictions in calibration data closely matched the validation set, indicating tree regeneration scenarios are reliable. Early stage post-harvest regeneration is similar to post-fire regeneration and matches the pattern of long-term natural vegetation distribution, confirming that site environmental factors are more important than management practices. Post-harvest natural regeneration of tree species increases under moderate warming scenarios, but fails under strong warming scenarios in landscape positions with high temperatures and low precipitation. Under all warming scenarios, the most successful regenerating species following white spruce harvest is white spruce. Birch experiences about 30% regeneration failure under A2 scenario by 2050. White spruce and aspen are projected to regenerate more successfully when site preparation is applied. Although white spruce has been the major managed species, birch may require more intensive management. Sites likely to experience regeneration failure of current tree species apparently will experience biome shift, although adaptive migration of existing or new species might be an option. Our scenario modeling tool allows resource managers to forecast tree regeneration on productive managed sites that have made a disproportionate contribution to carbon flux in a critical region.

  2. Adventitious shoots induction and plant regeneration from ...

    African Journals Online (AJOL)

    A highly efficient regeneration system is a prerequisite step for successful genetic transformation of watermelon cultivars (Citrullus lanatus L.). The objective of this study was to establish efficient in vitro plant regeneration for three watermelon cultivars. To achieve optimal conditions for adventitious shoot induction, the ...

  3. Adventitious shoots induction and plant regeneration from ...

    African Journals Online (AJOL)

    Aghomotsegin

    2015-07-08

    Jul 8, 2015 ... A highly efficient regeneration system is a prerequisite step for successful genetic transformation of watermelon cultivars (Citrullus lanatus L.). The objective of this study was to establish efficient in vitro plant regeneration for three watermelon cultivars. To achieve optimal conditions for adventitious.

  4. Clinical implications of advances in liver regeneration.

    Science.gov (United States)

    Kwon, Yong Jin; Lee, Kyeong Geun; Choi, Dongho

    2015-03-01

    Remarkable advances have been made recently in the area of liver regeneration. Even though liver regeneration after liver resection has been widely researched, new clinical applications have provided a better understanding of the process. Hepatic damage induces a process of regeneration that rarely occurs in normal undamaged liver. Many studies have concentrated on the mechanism of hepatocyte regeneration following liver damage. High mortality is usual in patients with terminal liver failure. Patients die when the regenerative process is unable to balance loss due to liver damage. During disease progression, cellular adaptations take place and the organ microenvironment changes. Portal vein embolization and the associating liver partition and portal vein ligation for staged hepatectomy are relatively recent techniques exploiting the remarkable progress in understanding liver regeneration. Living donor liver transplantation is one of the most significant clinical outcomes of research on liver regeneration. Another major clinical field involving liver regeneration is cell therapy using adult stem cells. The aim of this article is to provide an outline of the clinical approaches being undertaken to examine regeneration in liver diseases.

  5. Enhanced regeneration in explants of tomato (Lycopersicon ...

    African Journals Online (AJOL)

    USER

    2010-06-14

    Jun 14, 2010 ... Significant differences for regeneration, time taken to regenerate and number of leaf primordial were observed for different ... caused by fungi, bacteria, viruses and various nematodes. Development of protocols for in vitro ... high quality tomato seedlings via tissue culture could help to reduce the price per ...

  6. Beta secretase activity in peripheral nerve regeneration

    Directory of Open Access Journals (Sweden)

    Carolyn Tallon

    2017-01-01

    Full Text Available While the peripheral nervous system has the capacity to regenerate following a nerve injury, it is often at a slow rate and results in unsatisfactory recovery, leaving patients with reduced function. Many regeneration associated genes have been identified over the years, which may shed some insight into how we can manipulate this intrinsic regenerative ability to enhance repair following peripheral nerve injuries. Our lab has identified the membrane bound protease beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1, or beta secretase, as a potential negative regulator of peripheral nerve regeneration. When beta secretase activity levels are abolished via a null mutation in mice, peripheral regeneration is enhanced following a sciatic nerve crush injury. Conversely, when activity levels are greatly increased by overexpressing beta secretase in mice, nerve regeneration and functional recovery are impaired after a sciatic nerve crush injury. In addition to our work, many substrates of beta secretase have been found to be involved in regulating neurite outgrowth and some have even been identified as regeneration associated genes. In this review, we set out to discuss BACE1 and its substrates with respect to axonal regeneration and speculate on the possibility of utilizing BACE1 inhibitors to enhance regeneration following acute nerve injury and potential uses in peripheral neuropathies.

  7. High-Affinity DNA Aptamer Generation Targeting von Willebrand Factor A1-Domain by Genetic Alphabet Expansion for Systematic Evolution of Ligands by Exponential Enrichment Using Two Types of Libraries Composed of Five Different Bases.

    Science.gov (United States)

    Matsunaga, Ken-Ichiro; Kimoto, Michiko; Hirao, Ichiro

    2017-01-11

    The novel evolutionary engineering method ExSELEX (genetic alphabet expansion for systematic evolution of ligands by exponential enrichment) provides high-affinity DNA aptamers that specifically bind to target molecules, by introducing an artificial hydrophobic base analogue as a fifth component into DNA aptamers. Here, we present a newer version of ExSELEX, using a library with completely randomized sequences consisting of five components: four natural bases and one unnatural hydrophobic base, 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds). In contrast to the limited number of Ds-containing sequence combinations in our previous library, the increased complexity of the new randomized library could improve the success rates of high-affinity aptamer generation. To this end, we developed a sequencing method for each clone in the enriched library after several rounds of selection. Using the improved library, we generated a Ds-containing DNA aptamer targeting von Willebrand factor A1-domain (vWF) with significantly higher affinity (KD = 75 pM), relative to those generated by the initial version of ExSELEX, as well as that of the known DNA aptamer consisting of only the natural bases. In addition, the Ds-containing DNA aptamer was stabilized by introducing a mini-hairpin DNA resistant to nucleases, without any loss of affinity (KD = 61 pM). This new version is expected to consistently produce high-affinity DNA aptamers.

  8. Complement components of nerve regeneration conditioned fluid influence the microenvironment of nerve regeneration

    Directory of Open Access Journals (Sweden)

    Guang-shuai Li

    2016-01-01

    Full Text Available Nerve regeneration conditioned fluid is secreted by nerve stumps inside a nerve regeneration chamber. A better understanding of the proteinogram of nerve regeneration conditioned fluid can provide evidence for studying the role of the microenvironment in peripheral nerve regeneration. In this study, we used cylindrical silicone tubes as the nerve regeneration chamber model for the repair of injured rat sciatic nerve. Isobaric tags for relative and absolute quantitation proteomics technology and western blot analysis confirmed that there were more than 10 complement components (complement factor I, C1q-A, C1q-B, C2, C3, C4, C5, C7, C8ß and complement factor D in the nerve regeneration conditioned fluid and each varied at different time points. These findings suggest that all these complement components have a functional role in nerve regeneration.

  9. Regeneration limit of classical Shannon capacity

    Science.gov (United States)

    Sorokina, M. A.; Turitsyn, S. K.

    2014-05-01

    Since Shannon derived the seminal formula for the capacity of the additive linear white Gaussian noise channel, it has commonly been interpreted as the ultimate limit of error-free information transmission rate. However, the capacity above the corresponding linear channel limit can be achieved when noise is suppressed using nonlinear elements; that is, the regenerative function not available in linear systems. Regeneration is a fundamental concept that extends from biology to optical communications. All-optical regeneration of coherent signal has attracted particular attention. Surprisingly, the quantitative impact of regeneration on the Shannon capacity has remained unstudied. Here we propose a new method of designing regenerative transmission systems with capacity that is higher than the corresponding linear channel, and illustrate it by proposing application of the Fourier transform for efficient regeneration of multilevel multidimensional signals. The regenerative Shannon limit—the upper bound of regeneration efficiency—is derived.

  10. Tityus: a forgotten myth of liver regeneration.

    Science.gov (United States)

    Tiniakos, Dina G; Kandilis, Apostolos; Geller, Stephen A

    2010-08-01

    The ancient Greek myth of Tityus is related to liver regeneration in the same way as the well known myth of Prometheus is. Depictions of the punishment of Prometheus are frequently used by lecturers on liver regeneration; however, Tityus remains unknown despite the fact that he received the same punishment and his myth could also be used as a paradigm for the organ's extraordinary ability to regenerate. Nevertheless, there is no convincing evidence that ancient Greeks had any specific knowledge about liver regeneration, a concept introduced in the early 19th century. We describe and analyze the myth of Tityus and compare it to the myth of Prometheus. We also explore artistic and literary links and summarize recent scientific data on the mechanisms of liver regeneration. Finally, we highlight links of the legend of Tityus with other sciences. Copyright 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  11. Spinal cord regeneration in Xenopus laevis.

    Science.gov (United States)

    Edwards-Faret, Gabriela; Muñoz, Rosana; Méndez-Olivos, Emilio E; Lee-Liu, Dasfne; Tapia, Victor S; Larraín, Juan

    2017-02-01

    Here we present a protocol for the husbandry of Xenopus laevis tadpoles and froglets, and procedures to study spinal cord regeneration. This includes methods to induce spinal cord injury (SCI); DNA and morpholino electroporation for genetic studies; in vivo imaging for cell analysis; a swimming test to measure functional recovery; and a convenient model for screening for new compounds that promote neural regeneration. These protocols establish X. laevis as a unique model organism for understanding spinal cord regeneration by comparing regenerative and nonregenerative stages. This protocol can be used to understand the molecular and cellular mechanisms involved in nervous system regeneration, including neural stem and progenitor cell (NSPC) proliferation and neurogenesis, extrinsic and intrinsic mechanisms involved in axon regeneration, glial response and scar formation, and trophic factors. For experienced personnel, husbandry takes 1-2 months; SCI can be achieved in 5-15 min; and swimming recovery takes 20-30 d.

  12. Current Bioengineering Methods for Whole Kidney Regeneration

    Directory of Open Access Journals (Sweden)

    Shuichiro Yamanaka

    2015-01-01

    Full Text Available Kidney regeneration is likely to provide an inexhaustible source of tissues and organs for immunosuppression-free transplantation. It is currently garnering considerable attention and might replace kidney dialysis as the ultimate therapeutic strategy for renal failure. However, anatomical complications make kidney regeneration difficult. Here, we review recent advances in the field of kidney regeneration, including (i the directed differentiation of induced pluripotent stem cells/embryonic stem cells into kidney cells; (ii blastocyst decomplementation; (iii use of a decellularized cadaveric scaffold; (iv embryonic organ transplantation; and (v use of a nephrogenic niche for growing xenoembryos for de novo kidney regeneration from stem cells. All these approaches represent potentially promising therapeutic strategies for the treatment of patients with chronic kidney disease. Although many obstacles to kidney regeneration remain, we hope that innovative strategies and reliable research will ultimately allow the restoration of renal function in patients with end-stage kidney disease.

  13. Effect of rainfall and tillage direction on the evolution of surface crusts, soil hydraulic properties and runoff generation for a sandy loam soil

    Science.gov (United States)

    Ndiaye, Babacar; Esteves, Michel; Vandervaere, Jean-Pierre; Lapetite, Jean-Marc; Vauclin, Michel

    2005-06-01

    The study was aimed at evaluating the effect of rainfall and tillage-induced soil surface characteristics on infiltration and runoff on a 2.8 ha catchment located in the central region of Senegal. This was done by simulating 30 min rain storms applied at a constant rate of about 70 mm h -1, on 10 runoff micro-plots of 1 m 2, five being freshly harrowed perpendicularly to the slope and five along the slope (1%) of the catchment. Runoff was automatically recorded at the outlet of each plot. Hydraulic properties such as capillary sorptivity and hydraulic conductivity of the sandy loam soil close to saturation were determined by running 48 infiltration tests with a tension disc infiltrometer. That allowed the calculation of a mean characteristic pore size hydraulically active and a time to ponding. Superficial water storage capacity was estimated using data collected with an electronic relief meter. Because the soil was subject to surface crusting, crust-types as well as their spatial distribution within micro-plots and their evolution with time were identified and monitored by taking photographs at different times after tillage. The results showed that the surface crust-types as well as their tillage dependent dynamics greatly explain the decrease of hydraulic conductivity and sorptivity as the cumulative rainfall since tillage increases. The exponential decaying rates were found to be significantly greater for the soil harrowed along the slope (where the runoff crust-type covers more than 60% of the surface after 140 mm of rain) than across to the slope (where crusts are mainly of structural (60%) and erosion (40%) types). That makes ponding time smaller and runoff more important. Also it was shown that soil hydraulic properties after about 160 mm of rain were close to those of untilled plot not submitted to any rain. That indicates that the effects of tillage are short lived.

  14. The rise of the starlet sea anemone Nematostella vectensis as a model system to investigate development and regeneration.

    Science.gov (United States)

    Layden, Michael J; Rentzsch, Fabian; Röttinger, Eric

    2016-07-01

    Reverse genetics and next-generation sequencing unlocked a new era in biology. It is now possible to identify an animal(s) with the unique biology most relevant to a particular question and rapidly generate tools to functionally dissect that biology. This review highlights the rise of one such novel model system, the starlet sea anemone Nematostella vectensis. Nematostella is a cnidarian (corals, jellyfish, hydras, sea anemones, etc.) animal that was originally targeted by EvoDevo researchers looking to identify a cnidarian animal to which the development of bilaterians (insects, worms, echinoderms, vertebrates, mollusks, etc.) could be compared. Studies in Nematostella have accomplished this goal and informed our understanding of the evolution of key bilaterian features. However, Nematostella is now going beyond its intended utility with potential as a model to better understand other areas such as regenerative biology, EcoDevo, or stress response. This review intends to highlight key EvoDevo insights from Nematostella that guide our understanding about the evolution of axial patterning mechanisms, mesoderm, and nervous systems in bilaterians, as well as to discuss briefly the potential of Nematostella as a model to better understand the relationship between development and regeneration. Lastly, the sum of research to date in Nematostella has generated a variety of tools that aided the rise of Nematostella to a viable model system. We provide a catalogue of current resources and techniques available to facilitate investigators interested in incorporating Nematostella into their research. WIREs Dev Biol 2016, 5:408-428. doi: 10.1002/wdev.222 For further resources related to this article, please visit the WIREs website. © 2016 The Authors. WIREs Developmental Biology published by Wiley Periodicals, Inc.

  15. Integrin suppresses neurogenesis and regulates brain tissue assembly in planarian regeneration.

    Science.gov (United States)

    Bonar, Nicolle A; Petersen, Christian P

    2017-03-01

    Animals capable of adult regeneration require specific signaling to control injury-induced cell proliferation, specification and patterning, but comparatively little is known about how the regeneration blastema assembles differentiating cells into well-structured functional tissues. Using the planarian Schmidtea mediterranea as a model, we identify β1-integrin as a crucial regulator of blastema architecture. β1-integrin(RNAi) animals formed small head blastemas with severe tissue disorganization, including ectopic neural spheroids containing differentiated neurons normally found in distinct organs. By mimicking aspects of normal brain architecture but without normal cell-type regionalization, these spheroids bore a resemblance to mammalian tissue organoids synthesized in vitro We identified one of four planarian integrin-alpha subunits inhibition of which phenocopied these effects, suggesting that a specific receptor controls brain organization through regeneration. Neoblast stem cells and progenitor cells were mislocalized in β1-integrin(RNAi) animals without significantly altered body-wide patterning. Furthermore, tissue disorganization phenotypes were most pronounced in animals undergoing brain regeneration and not homeostatic maintenance or regeneration-induced remodeling of the brain. These results suggest that integrin signaling ensures proper progenitor recruitment after injury, enabling the generation of large-scale tissue organization within the regeneration blastema. © 2017. Published by The Company of Biologists Ltd.

  16. Mest but Not MiR-335 Affects Skeletal Muscle Growth and Regeneration

    Science.gov (United States)

    Hiramuki, Yosuke; Sato, Takahiko; Furuta, Yasuhide; Surani, M. Azim; Sehara-Fujisawa, Atsuko

    2015-01-01

    When skeletal muscle fibers are injured, they regenerate and grow until their sizes are adjusted to surrounding muscle fibers and other relevant organs. In this study, we examined whether Mest, one of paternally expressed imprinted genes that regulates body size during development, and miR-335 located in the second intron of the Mest gene play roles in muscle regeneration. We generated miR-335-deficient mice, and found that miR-335 is a paternally expressed imprinted microRNA. Although both Mest and miR-335 are highly expressed during muscle development and regeneration, only Mest+/- (maternal/paternal) mice show retardation of body growth. In addition to reduced body weight in Mest+/-; DMD-null mice, decreased muscle growth was observed in Mest+/- mice during cardiotoxin-induced regeneration, suggesting roles of Mest in muscle regeneration. Moreover, expressions of H19 and Igf2r, maternally expressed imprinted genes were affected in tibialis anterior muscle of Mest+/-; DMD-null mice compared to DMD-null mice. Thus, Mest likely mediates muscle regeneration through regulation of imprinted gene networks in skeletal muscle. PMID:26098312

  17. Visualizing Peripheral Nerve Regeneration by Whole Mount Staining

    Science.gov (United States)

    Dun, Xin-peng; Parkinson, David B.

    2015-01-01

    Peripheral nerve trauma triggers a well characterised sequence of events both proximal and distal to the site of injury. Axons distal to the injury degenerate, Schwann cells convert to a repair supportive phenotype and macrophages enter the nerve to clear myelin and axonal debris. Following these events, axons must regrow through the distal part of the nerve, re-innervate and finally are re-myelinated by Schwann cells. For nerve crush injuries (axonotmesis), in which the integrity of the nerve is maintained, repair may be relatively effective whereas for nerve transection (neurotmesis) repair will likely be very poor as few axons may be able to cross between the two parts of the severed nerve, across the newly generated nerve bridge, to enter the distal stump and regenerate. Analysing axon growth and the cell-cell interactions that occur following both nerve crush and cut injuries has largely been carried out by staining sections of nerve tissue, but this has the obvious disadvantage that it is not possible to follow the paths of regenerating axons in three dimensions within the nerve trunk or nerve bridge. To try and solve this problem, we describe the development and use of a novel whole mount staining protocol that allows the analysis of axonal regeneration, Schwann cell-axon interaction and re-vascularisation of the repairing nerve following nerve cut and crush injuries. PMID:25738874

  18. Visualizing peripheral nerve regeneration by whole mount staining.

    Directory of Open Access Journals (Sweden)

    Xin-peng Dun

    Full Text Available Peripheral nerve trauma triggers a well characterised sequence of events both proximal and distal to the site of injury. Axons distal to the injury degenerate, Schwann cells convert to a repair supportive phenotype and macrophages enter the nerve to clear myelin and axonal debris. Following these events, axons must regrow through the distal part of the nerve, re-innervate and finally are re-myelinated by Schwann cells. For nerve crush injuries (axonotmesis, in which the integrity of the nerve is maintained, repair may be relatively effective whereas for nerve transection (neurotmesis repair will likely be very poor as few axons may be able to cross between the two parts of the severed nerve, across the newly generated nerve bridge, to enter the distal stump and regenerate. Analysing axon growth and the cell-cell interactions that occur following both nerve crush and cut injuries has largely been carried out by staining sections of nerve tissue, but this has the obvious disadvantage that it is not possible to follow the paths of regenerating axons in three dimensions within the nerve trunk or nerve bridge. To try and solve this problem, we describe the development and use of a novel whole mount staining protocol that allows the analysis of axonal regeneration, Schwann cell-axon interaction and re-vascularisation of the repairing nerve following nerve cut and crush injuries.

  19. Müller glia cell reprogramming and retina regeneration

    Science.gov (United States)

    Goldman, Daniel

    2014-01-01

    Müller glia are the major glial component of the retina. They are one of the last retinal cell types to be born during development and they function to maintain retinal homeostasis and integrity. In mammals, Müller glia respond to retinal injury in a variety of ways that can be either protective or detrimental to retinal function. Although under special circumstances these cells can be coaxed to proliferate and generate neurons, these responses are meager and insufficient for repairing a damaged retina. By contrast, in teleost fish (such as zebrafish) the response of Müller glia to retinal injury involves a reprogramming event that imparts retinal stem cell characteristics and allows them to produce a proliferating population of progenitors that can regenerate all major retinal cell types and restore vision. Recent studies have revealed a number of important mechanisms underlying Müller glia reprogramming and retina regeneration in fish that may lead to new strategies for stimulating retina regeneration in mammals. PMID:24894585

  20. Hydrogel based cartilaginous tissue regeneration: recent insights and technologies.

    Science.gov (United States)

    Chuah, Yon Jin; Peck, Yvonne; Lau, Jia En Josias; Hee, Hwan Tak; Wang, Dong-An

    2017-03-28

    Hydrogels have been extensively employed as an attractive biomaterial to address numerous existing challenges in the fields of regenerative medicine and research because of their unique properties such as the capability to encapsulate cells, high water content, ease of modification, low toxicity, injectability, in situ spatial fit and biocompatibility. These inherent properties have created many opportunities for hydrogels as a scaffold or a cell/drug carrier in tissue regeneration, especially in the field of cartilaginous tissue such as articular cartilage and intervertebral discs. A concise overview of the anatomy/physiology of these cartilaginous tissues and their pathophysiology, epidemiology and existing clinical treatments will be briefly described. This review article will discuss the current state-of-the-art of various polymers and developing strategies that are explored in establishing different technologies for cartilaginous tissue regeneration. In particular, an innovative approach to generate scaffold-free cartilaginous tissue via a transient hydrogel scaffolding system for disease modeling to pre-clinical trials will be examined. Following that, the article reviews numerous hydrogel-based medical implants used in clinical treatment of osteoarthritis and degenerated discs. Last but not least, the challenges and future directions of hydrogel based medical implants in the regeneration of cartilaginous tissue are also discussed.

  1. Fibroblasts as maestros orchestrating tissue regeneration.

    Science.gov (United States)

    Costa-Almeida, Raquel; Soares, Raquel; Granja, Pedro L

    2017-01-20

    Fibroblasts constitute a dynamic and versatile population of cells of mesenchymal origin, implicated in both regenerative strategies and pathological conditions. Despite being frequently associated to disease development, particularly through the establishment of fibrotic tissue, fibroblasts hold great potential for tissue engineering and regenerative medicine applications. They are responsible for synthesizing and depositing extracellular matrix components, allowing other cells to settle and migrate along a three-dimensional support and thereby generating an organ-specific architecture. Additionally, they produce bioactive molecules that are involved in several physiological processes, including angiogenesis and tissue repair. Although there seems to be much still to unveil about these fascinating cells they have been attracting increasing interest and are now being intensively explored as a cell source to develop bioengineered tissue constructs or to improve stem cell-based technologies. This review intends to highlight the potential of fibroblasts in orchestrating tissue regeneration, as well as to contribute to uncover uncharted prospective applications of these cells. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  2. Asexual propagation and regeneration in colonial ascidians.

    Science.gov (United States)

    Kürn, Ulrich; Rendulic, Snjezana; Tiozzo, Stefano; Lauzon, Robert J

    2011-08-01

    Regeneration is widely distributed among the metazoans. However, clear differences exist as to the degree of regenerative capacity: some phyla can only replace missing body parts, whereas others can generate entirely new individuals. Ascidians are animals that possess a remarkable regenerative plasticity and exhibit a great diversity of mechanisms for asexual propagation and survival. They are marine invertebrate members of the subphylum Tunicata and represent modern-day descendants of the chordate ancestor; in their tadpole stage they exhibit a chordate body plan that is resorbed during metamorphosis. Solitary species grow into an adult that can reach several centimeters in length, whereas colonial species grow by asexual propagation, creating a colony of genetically identical individuals. In this review, we present an overview of the biology of colonial ascidians as a paradigm for study in stem cell and regenerative biology. Focusing on botryllid ascidians, we introduce the potential roles played by multipotent epithelia and multipotent/pluripotent stem cells as source of asexual propagation and regenerative plasticity in the different budding mechanisms, and consider the putative mechanism of body repatterning in a non-embryonic scenario. We also discuss the involvement of intra-colony homeostatic processes in regulating budding potential, and the functional link between allorecognition, chimerism, and regenerative potential.

  3. Bioinspired scaffolds for osteochondral regeneration.

    Science.gov (United States)

    Lopa, Silvia; Madry, Henning

    2014-08-01

    Osteochondral defects are difficult to treat because the articular cartilage and the subchondral bone have dissimilar characteristics and abilities to regenerate. Bioinspired scaffolds are designed to mimic structural and biological cues of the native osteochondral unit, supporting both cartilaginous and subchondral bone repair and the integration of the newly formed osteochondral matrix with the surrounding tissues. The aim of this review is to outline fundamental requirements and strategies for the development of biomimetic scaffolds reproducing the unique and multifaceted anatomical structure of the osteochondral unit. Recent progress in preclinical animal studies using bilayer and multilayer scaffolds, together with continuous gradient scaffolds will be discussed and placed in a translational perspective with data emerging from their clinical application to treat osteochondral defects in patients.

  4. Reintegration of the regenerated and the remaining tissues during joint regeneration in the newt Cynops pyrrhogaster

    Science.gov (United States)

    Inoue, Takeshi; Yamada, Shigehito

    2015-01-01

    Abstract Urodele amphibians, such as newts, can regenerate a functional limb, including joints, after amputation at any level along the proximal−distal axis of the limb. The blastema can regenerate the limb morphology largely independently of the stump after proximal−distal identity has been established, but the remaining and regenerated tissues must be structurally reintegrated (matched in size and shape). Here we used newt joint regeneration as a model to investigate reintegration, because a functionally interlocking joint requires structural integration between its opposing skeletal elements. After forelimbs were amputated at the elbow joint, the joint was regenerated between the remaining and regenerated skeletal elements. The regenerated cartilage was thick around the amputated joint to make a reciprocally interlocking joint structure with the remaining bone. Furthermore, during regeneration, the extracellular matrix of the remaining tissues was lost, suggesting that the remaining tissues might contribute to the morphogenesis of regenerating cartilage. Our results showed that the area of the regenerated cartilage matched the area of the apposed remaining cartilage, thus contributing to formation of a functional structure. PMID:27499865

  5. Weak Evidence of Regeneration Habitat but Strong Evidence of Regeneration Niche for a Leguminous Shrub.

    Directory of Open Access Journals (Sweden)

    Florian Delerue

    Full Text Available The identification of an ecological niche specific to the regeneration phase has mobilised significant attention. However, the importance of the regeneration niche concept remains unclear. Our main objective was to study the existence of such a regeneration niche for a leguminous shrub, Ulex europaeus. This study was carried out in southwest France in the context of water and nutrient stresses (mainly phosphorus limitation due to the presence of nutrient-poor sandy soils. We analysed the regeneration of the species from the germination of seeds and emergence of new seedlings until the seedlings reached young shrub size. Our design included a P fertilisation treatment. We also investigated microsite characteristics (micro-topography and vegetation development as they can interact with meteorological conditions and determine water availability for seeds and seedlings. We found that P availability controlled seedling growth and the time necessary to reach young shrub size. Water availability appeared to impact the species germination and seedlings survival. We also found that P and water availability depended on the interactions between microsite characteristics and climatic variations. Finally we found evidence that P and water availability are important ecological factors shaping the regeneration niche of the species, but we found weak evidence that any microsite would be appropriate for the regeneration of the species in the long term. Future studies regarding regeneration niches need to distinguish more clearly the ecological factors important for regeneration (the regeneration niche per se and the physical world where the seedlings appear and develop (the regeneration habitat.

  6. Weak Evidence of Regeneration Habitat but Strong Evidence of Regeneration Niche for a Leguminous Shrub

    Science.gov (United States)

    Delerue, Florian; Gonzalez, Maya; Michalet, Richard; Pellerin, Sylvain; Augusto, Laurent

    2015-01-01

    The identification of an ecological niche specific to the regeneration phase has mobilised significant attention. However, the importance of the regeneration niche concept remains unclear. Our main objective was to study the existence of such a regeneration niche for a leguminous shrub, Ulex europaeus. This study was carried out in southwest France in the context of water and nutrient stresses (mainly phosphorus limitation) due to the presence of nutrient-poor sandy soils. We analysed the regeneration of the species from the germination of seeds and emergence of new seedlings until the seedlings reached young shrub size. Our design included a P fertilisation treatment. We also investigated microsite characteristics (micro-topography and vegetation development) as they can interact with meteorological conditions and determine water availability for seeds and seedlings. We found that P availability controlled seedling growth and the time necessary to reach young shrub size. Water availability appeared to impact the species germination and seedlings survival. We also found that P and water availability depended on the interactions between microsite characteristics and climatic variations. Finally we found evidence that P and water availability are important ecological factors shaping the regeneration niche of the species, but we found weak evidence that any microsite would be appropriate for the regeneration of the species in the long term. Future studies regarding regeneration niches need to distinguish more clearly the ecological factors important for regeneration (the regeneration niche per se) and the physical world where the seedlings appear and develop (the regeneration habitat). PMID:26098877

  7. Wavelet dimensions and time evolution

    OpenAIRE

    Guérin, Charles-Antoine; Holschneider, Matthias

    1999-01-01

    International audience; In this chapter, we study some aspects of the chaotic behaviour of the time evolution generated by Hamiltonian systems, or more generally dynamical systems. We introduce a characteristic quantity, namely the lacunarity dimension, to quantify the intermittency phenomena that can arise in the time evolution. We then focus on the time evolution of wave packets according to the Schrödinger equation with time independent Hamiltonian. We introduce a set of fractal dimensions...

  8. System and method for regeneration and recirculation of a reducing agent using highly exothermic reactions induced by mixed industrial slags

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Jinichiro; Bennett, James P.; Nakano, Anna

    2017-12-12

    Embodiments relate to systems and methods for regenerating and recirculating a CO, H.sub.2 or combinations thereof utilized for metal oxide reduction in a reduction furnace. The reduction furnace receives the reducing agent, reduces the metal oxide, and generates an exhaust of the oxidized product. The oxidized product is transferred to a mixing vessel, where the oxidized product, a calcium oxide, and a vanadium oxide interact to regenerate the reducing agent from the oxidized product. The regenerated reducing agent is transferred back to the reduction furnace for continued metal oxide reductions.

  9. MSC/ECM Cellular Complexes Induce Periodontal Tissue Regeneration.

    Science.gov (United States)

    Takewaki, M; Kajiya, M; Takeda, K; Sasaki, S; Motoike, S; Komatsu, N; Matsuda, S; Ouhara, K; Mizuno, N; Fujita, T; Kurihara, H

    2017-08-01

    Transplantation of mesenchymal stem cells (MSCs), which possess self-renewing properties and multipotency, into a periodontal defect is thought to be a useful option for periodontal tissue regeneration. However, developing more reliable and predictable implantation techniques is still needed. Recently, we generated clumps of an MSC/extracellular matrix (ECM) complex (C-MSC), which consisted of cells and self-produced ECM. C-MSCs can regulate their cellular functions in vitro and can be grafted into a defect site, without any artificial scaffold, to induce bone regeneration. Accordingly, this study aimed to evaluate the effect of C-MSC transplantation on periodontal tissue regeneration in beagle dogs. Seven beagle dogs were employed to generate a premolar class III furcation defect model. MSCs isolated from dog ilium were seeded at a density of 7.0 × 104 cells/well into 24-well plates and cultured in growth medium supplemented with 50 µg/mL ascorbic acid for 4 d. To obtain C-MSCs, confluent cells were scratched using a micropipette tip and were then torn off as a cellular sheet. The sheet was rolled up to make round clumps of cells. C-MSCs were maintained in growth medium or osteoinductive medium (OIM) for 5 or 10 d. The biological properties of C-MSCs were evaluated in vitro, and their periodontal tissue regenerative activity was tested by using a dog class III furcation defect model. Immunofluorescence analysis revealed that type I collagen fabricated the form of C-MSCs. OIM markedly elevated calcium deposition in C-MSCs at day 10, suggesting its osteogenic differentiation capacity. Both C-MSCs and C-MSCs cultured with OIM transplantation without an artificial scaffold into the dog furcation defect induced periodontal tissue regeneration successfully compared with no graft, whereas osteogenic-differentiated C-MSCs led to rapid alveolar bone regeneration. These findings suggested that the use of C-MSCs refined by self-produced ECM may represent a novel

  10. Solar fuel generator

    Science.gov (United States)

    Lewis, Nathan S.; West, William C.

    2017-01-17

    The disclosure provides conductive membranes for water splitting and solar fuel generation. The membranes comprise an embedded semiconductive/photoactive material and an oxygen or hydrogen evolution catalyst. Also provided are chassis and cassettes containing the membranes for use in fuel generation.

  11. Solar Fuel Generator

    Science.gov (United States)

    Lewis, Nathan S. (Inventor); West, William C. (Inventor)

    2017-01-01

    The disclosure provides conductive membranes for water splitting and solar fuel generation. The membranes comprise an embedded semiconductive/photoactive material and an oxygen or hydrogen evolution catalyst. Also provided are chassis and cassettes containing the membranes for use in fuel generation.

  12. Grand Views of Evolution.

    Science.gov (United States)

    de Vladar, Harold P; Santos, Mauro; Szathmáry, Eörs

    2017-05-01

    Despite major advances in evolutionary theories, some aspects of evolution remain neglected: whether evolution: would come to a halt without abiotic change; is unbounded and open-ended; or is progressive and something beyond fitness is maximized. Here, we discuss some models of ecology and evolution and argue that ecological change, resulting in Red Queen dynamics, facilitates (but does not ensure) innovation. We distinguish three forms of open-endedness. In weak open-endedness, novel phenotypes can occur indefinitely. Strong open-endedness requires the continual appearance of evolutionary novelties and/or innovations. Ultimate open-endedness entails an indefinite increase in complexity, which requires unlimited heredity. Open-ended innovation needs exaptations that generate novel niches. This can result in new traits and new rules as the dynamics unfolds, suggesting that evolution is not fully algorithmic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Optical Regeneration and Noise in Semiconductor Devices

    DEFF Research Database (Denmark)

    Öhman, Filip

    2005-01-01

    In this report all-optical 2R-regeneration in optical communication systems is investigated. A simple regenerator device based on concatenated semiconductor optical amplifiers (SOAs) and electro absorbers (EAs) is introduced and examined. Experiments show that the monolithic SOA-EA 2R-regenerator......In this report all-optical 2R-regeneration in optical communication systems is investigated. A simple regenerator device based on concatenated semiconductor optical amplifiers (SOAs) and electro absorbers (EAs) is introduced and examined. Experiments show that the monolithic SOA-EA 2R...... sensitivity with more than 8 dB compared to the back-to-back case, using a degraded signal. The noise properties and cascadability of the proposed device are examined through modeling. Furthermore the influence of the saturation properties of the EA on the regeneration performance is investigated....... Calculations show that it is possible to increase the nonlinearity of the transfer function and improve the regenerating properties by lowering the saturation power of the EA and concatenating several SOA-EA pairs, although this also adds more noise to the signal. In order to analyze the influence...

  14. [Tooth regeneration--dream to reality].

    Science.gov (United States)

    Wang, Song-Ling; Wang, Xue-Jiu

    2008-04-01

    Tooth or dentition missing compromises human health physically and psychiatrically. Although several prosthesis methods are used to restore tooth loss, these restorations are still non-biological methods. It is a dream for human being to regenerate a real tooth for hundreds years. There are two ways to regenerate the tooth. One is application of conventional tissue engineering techniques including seed cells and scaffold. The other is regeneration tooth using dental epithelium and dental mesenchymal cells based on the knowledge of tooth initiation and development. Marked progress has been achieved in these two ways, while there is still a long way to go. Recently a new concept has been proposed for regeneration of a biological tooth root based on tooth-related stem cells and tissue engineering technique. A biological tooth root has been regenerated in swine. It may be a valuable method for restoration of tooth loss before successful whole tooth regeneration. A latest research showed that a subpopulation in bone marrow cells can give rise to ameloblast-like cells when mixed with embryonic epithelium and reassociation with integrated mesenchyme, which may provide a new seed cell source for tooth regeneration.

  15. Spatiotemporal Evolution of Ar(3P2) Metastable Density Generated in a Pulsed DC Atmospheric Pressure micro-Plasma Jet Impinging on a Glass Plate

    Science.gov (United States)

    Gazeli, K.; Bauville, G.; Es-Sebbar, Et-T.; Fleury, M.; Neveau, O.; Pasquiers, St.; Santos Sousa, J.; Laboratoire de Physique des gaz et des plasmas Team

    2016-09-01

    Atmospheric Pressure micro-Plasma Jets (APPJs) are promising tools in various domains such as biomedical and material treatments. In this work, APPJs are produced in pure argon at variable flow rates (i.e., 200, 400 and 600 sccm), by applying high voltage positive pulses (250 ns in FWHM and 6 kV in amplitude) at a repetition frequency of 20 kHz. The generated plasma impacts an ungrounded glass plate placed at a distance of 5 mm from the tube's orifice and perpendicular to the streamers propagation. At these conditions, a diffuse discharge is established resulting in a non-filamentary and reproducible plasma, in contrast with the free-jet case (no target). This allows the quantification of the absolute density of the Ar(1s5) metastable state by using laser absorption spectroscopy to probe the transition 1s5 -> 2p9 at 811.531 nm. The experiments show the dependence on the gas flow rate and on the axial and radial positions of the maximum density (6-9x1013 cm-3) . At 200 sccm, it is obtained close to the tube's orifice, while with increasing flow rate it is displaced towards the plate. Regarding the radial variation, density maxima are obtained in a small area around the streamers propagation axis.

  16. Next generation mobile broadcasting

    CERN Document Server

    Gómez-Barquero, David

    2013-01-01

    Next Generation Mobile Broadcasting provides an overview of the past, present, and future of mobile multimedia broadcasting. The first part of the book-Mobile Broadcasting Worldwide-summarizes next-generation mobile broadcasting technologies currently available. This part covers the evolutions of the Japanese mobile broadcasting standard ISDB-T One-Seg, ISDB-Tmm and ISDB-TSB; the evolution of the South Korean T-DMB mobile broadcasting technology AT-DMB; the American mobile broadcasting standard ATSC-M/H; the Chinese broadcasting technologies DTMB and CMMB; second-generation digital terrestrial

  17. Pulp regeneration: Current approaches and future challenges

    Directory of Open Access Journals (Sweden)

    Jingwen eYANG

    2016-03-01

    Full Text Available Regenerative endodontics aims to replace inflamed/necrotic pulp tissues with regenerated pulp-like tissues to revitalize teeth and improve life quality. Pulp revascularization case reports, which showed successful clinical and radiographic outcomes, indicated the possible clinical application of pulp regeneration via cell homing strategy. From a clinical point of view, functional pulp-like tissues should be regenerated with the characterization of vascularization, re-innervation, and dentin deposition with a regulated rate similar to that of normal pulp. Efficient root canal disinfection and proper size of the apical foramen are the two requisite preconditions for pulp regeneration. Progress has been made on pulp regeneration via cell homing strategies. This review focused on the requisite preconditions and cell homing strategies for pulp regeneration. In addition to the traditionally used mechanical preparation and irrigation, antibiotics, irrigation assisted with EndoVac apical negative-pressure system, and ultrasonic and laser irradiation are now being used in root canal disinfection. In addition, pulp-like tissues could be formed with the apical foramen less than 1 mm, although more studies are needed to determine the appropriate size. Moreover, signaling molecules including stromal cell derived factor (SDF-1α, basic Fibroblast Growth Factor (bFGF, Platelet Derived Growth Factor (PDGF, stem cell factor (SCF, and Granulocyte Colony-Stimulating Factor (G-CSF were used to achieve pulp-like tissue formation via a cell homing strategy. Studies on the cell sources of pulp regeneration might give some indications on the signaling molecular selection. The active recruitment of endogenous cells into root canals to regenerate pulp-like tissues is a novel concept that may offer an unprecedented opportunity for the near-term clinical translation of current biology-based therapies for dental pulp regeneration.

  18. Dynamic studies on flagellar regeneration in Dunaliella salina

    Science.gov (United States)

    Liu, Jian-Guo; Bourne, W. F.

    1999-09-01

    Flagella, the basic locomotive organ in algae, as well as bacteria and some cells of animals or high plants, would be damaged in the well stirred mass culture due to the strong forces caused by the fast mixing impellers. The dynamic regeneration of the flagella in deflagellated Dunaliella salina was studied microscopically by using a bench-top flat-bottom photobioreactor. The results showed that 90 minutes was necessary for the repair of flagella, after which half of the cells became motile as their flagella generated within 120 minutes and nearly all of the cells could swim freely within 180 minutes.

  19. Technologies for ECLSS Evolution

    Science.gov (United States)

    Diamant, Bryce L.

    1990-01-01

    Viewgraphs and discussion on technologies for Environmental Control and Life Support System (ECLSS) evolution are presented. Topics covered include: atmosphere revitalization including CO2 removal, CO2 reduction, O2 generation, and trace contaminant control; water recovery and management including urine processing, hygiene water processing, and potable water processing; and waste management. ECLSS technology schematics, process diagrams, and fluid interfaces are included.

  20. Mechanisms of Guided Bone Regeneration: A Review

    Science.gov (United States)

    Liu, Jie; Kerns, David G

    2014-01-01

    Post-extraction crestal bone resorption is common and unavoidable which can lead to significant ridge dimensional changes. To regenerate enough bone for successful implant placement, Guided Bone Regeneration (GBR) is often required. GBR is a surgical procedure that uses barrier membranes with or without particulate bone grafts or/and bone substitutes. There are two approaches of GBR in implant therapy: GBR at implant placement (simultaneous approach) and GBR before implant placement to increase the alveolar ridge or improve ridge morphology (staged approach). Angiogenesis and ample blood supply play a critical role in promoting bone regeneration. PMID:24894890

  1. Cardiac muscle regeneration: lessons from development

    Science.gov (United States)

    Mercola, Mark; Ruiz-Lozano, Pilar; Schneider, Michael D.

    2011-01-01

    The adult human heart is an ideal target for regenerative intervention since it does not functionally restore itself after injury yet has a modest regenerative capacity that could be enhanced by innovative therapies. Adult cardiac cells with regenerative potential share gene expression signatures with early fetal progenitors that give rise to multiple cardiac cell types, suggesting that the evolutionarily conserved regulatory networks that drive embryonic heart development might also control aspects of regeneration. Here we discuss commonalities of development and regeneration, and the application of the rich developmental biology heritage to achieve therapeutic regeneration of the human heart. PMID:21325131

  2. Functional Regeneration Beyond the Glial Scar

    Science.gov (United States)

    Cregg, Jared M.; DePaul, Marc A.; Filous, Angela R.; Lang, Brad T.; Tran, Amanda; Silver, Jerry

    2014-01-01

    Astrocytes react to CNS injury by building a dense wall of filamentous processes around the lesion. Stromal cells quickly take up residence in the lesion core and synthesize connective tissue elements that contribute to fibrosis. Oligodendrocyte precursor cells proliferate within the lesion and help to entrap dystrophic axon tips. Here we review evidence that this aggregate scar acts as the major barrier to regeneration of axons after injury. We also consider several exciting new interventions that allow axons to regenerate beyond the glial scar, and discuss the implications of this work for the future of regeneration biology. PMID:24424280

  3. Adventitious shoot formation and plant regeneration from leaf ...

    African Journals Online (AJOL)

    High root regeneration was obtained when the explants were cultured on medium with NAA only. Shoot regeneration was associated with callus formation. Regenerated shoots were rooted ex vitro, acclimatized and grown normally in the greenhouse. Keywords: Cytokinins, carnation, multiplication, regeneration, thidiazuron

  4. The planarian regeneration transcriptome reveals a shared but temporally shifted regulatory program between opposing head and tail scenarios.

    Science.gov (United States)

    Kao, Damian; Felix, Daniel; Aboobaker, Aziz

    2013-11-16

    Planarians can regenerate entire animals from a small fragment of the body. The regenerating fragment is able to create new tissues and remodel existing tissues to form a complete animal. Thus different fragments with very different starting components eventually converge on the same solution. In this study, we performed an extensive RNA-seq time-course on regenerating head and tail fragments to observe the differences and similarities of the transcriptional landscape between head and tail fragments during regeneration. We have consolidated existing transcriptomic data for S. mediterranea to generate a high confidence set of transcripts for use in genome wide expression studies. We performed a RNA-seq time-course on regenerating head and tail fragments from 0 hours to 3 days. We found that the transcriptome profiles of head and tail regeneration were very different at the start of regeneration; however, an unexpected convergence of transcriptional profiles occurred at 48 hours when head and tail fragments are still morphologically distinct. By comparing differentially expressed transcripts at various time-points, we revealed that this divergence/convergence pattern is caused by a shared regulatory program that runs early in heads and later in tails.Additionally, we also performed RNA-seq on smed-prep(RNAi) tail fragments which ultimately fail to regenerate anterior structures. We find the gene regulation program in response to smed-prep(RNAi) to display the opposite regulatory trend compared to the previously mentioned share regulatory program during regeneration. Using annotation data and comparative approaches, we also identified a set of approximately 4,800 triclad specific transcripts that were enriched amongst the genes displaying differential expression during the regeneration time-course. The regeneration transcriptome of head and tail regeneration provides us with a rich resource for investigating the global expression changes that occurs during

  5. Viscous dissipation as a regional thermal anomaly-generator process: implications on the evolution of Baja California post-subduction volcanism

    Science.gov (United States)

    Negrete-Aranda, R.; Contreras, J.

    2010-12-01

    An intriguing feature of the Baja California peninsula is that volcanic activity thrived and continued along the axis of the peninsula even after the cessation of subduction 10 Ma ago. Post-subduction volcanism in Baja California occurred mainly in monogenetic volcanic fields comprising a variety of compositions, most of them associated with high-temperature regimes and marked by a “slab” signature (i.e., adakites, Niobium-enriched basalts and high-magnesium andesites). Several attempts have been made to explain the origin and compositional diversity of such post-subduction volcanism. Many of them rely on the assumption that anomalous magmas are formed in direct response to tectonic events such as slab window formation or slab-tearing processes. However, none of them can offer a satisfactory explanation as to why volcanism as young as 1 Ma can be found along the Baja California peninsula. Observations elsewhere and in numerical simulations have shown that the slab tearing process is a fast one lasting only a few million years. By contrast the post-subduction volcanism in Baja California has lasted more than 10-million years. Here, we present a physical model that shed light into the origin of this controversial phenomenon. The model calls upon viscous dissipation or shear heating as the process responsible for the generation of a regional heat flow anomaly with a maximum amplitude of 40 mW/m2 clearly observed in deep boreholes drilled in the area. We hypothesize that at moderate depths it may have caused partial melting after the cessation of subduction along the Baja California. Our results show that indeed is possible for rocks to increase their temperatures substantially in this way. Preliminary numerical experimentation shows that the melt fraction could reach up to 10% and the maximum amount of shear heating could lead to a temperature increase close to 200 °C at 35 km depth. Moreover, the rise of magmas and/or hot fluids in the shear zone will enhance

  6. MEMBRANOUS FLOWS IN GAS-LIQUID COLLECTORS-REGENERATORS OF SOLAR ABSORPTIVE SYSTEMS FEATURES

    Directory of Open Access Journals (Sweden)

    Doroshenko А.V.

    2009-12-01

    Full Text Available Article is devoted to the creation of new generation of solar collectors of the gas-liquid type, intended for use in alternative refrigerating and conditioning systems of drying-evaporating type with direct solar regeneration of absorbent. Special attention is given to the study of membranous flows features on inclined surfaces, including questions of such flows stability.

  7. Regeneration in chalk grassland during 150 years in a military area

    NARCIS (Netherlands)

    Bakker, Jan P.

    2014-01-01

    The long-term regeneration of calcareous grassland after agricultural intensification is elucidated in Redhead etal. 2014 (Applied Vegetation Science 17: 408-418). The paper generates thoughts about the impact of different pre-purchase agricultural practices. It makes the reader think about the

  8. Osseointegration of subperiosteal implant via guided tissue regeneration. A pilot study

    DEFF Research Database (Denmark)

    Hjørting-Hansen, E; Helbo, M; Aaboe, M

    1995-01-01

    The principle of guided tissue regeneration was applied in an attempt to generate bone to cover a subperiosteal implant. Titanium frame works, casted on individual impressions of the anterior surface of the tibia of 4 Copenhagen White rabbits, were stabilized to the tibia by microscrews, and half...

  9. Mid-Tertiary magmatism in western Big Bend National Park, Texas, U.S.A.: Evolution of basaltic source regions and generation of peralkaline rhyolite

    Science.gov (United States)

    Parker, Don F.; Ren, Minghua; Adams, David T.; Tsai, Heng; Long, Leon E.

    2012-07-01

    then descended as magmatism died out. Variation within Burro Mesa Rhyolite is best explained by fractional crystallization of a mix of alkali feldspar, fayalite and Fe-Ti oxide. Comendite of the Burro Mesa Rhyolite evolved from trachyte as batches in relatively small independent magma systems, as suggested by widespread occurrence of trachytic magma enclaves within Burro Mesa lava and results of fractionation modeling. Trachyte may have been derived by fractional crystallization of intermediate magma similar to that erupted as part of Bee Mountain Basalt. ɛNdt values of trachyte lava (0.745) and two samples of Burro Mesa Rhyolite (- 0.52 and 1.52) are consistent with the above models. In all, ~ 5 wt.% comendite may be produced from 100 parts of parental trachybasalt. Negative Nb anomalies in some Bee Mountain, Tule Mountain Trachyte and Burro Mesa incompatible element plots may have been inherited from lithospheric mantle rather than from a descending plate associated with subduction. Late phase basalts lack such a Nb anomaly, as do all of our Alamo Creek analyses but one. Even if some slab fluids partially metasomatized lithospheric mantle, these igneous rocks are much more typical of continental rifts than continental arcs. We relate Big Bend magmatism to asthenospheric mantle upwelling accompanying foundering of the subducted Farallon slab as the convergence rate between the North American and the Farallon plates decreased beginning about 50 Ma. Upwelling asthenosphere heated the base of the continental lithosphere, producing the Alamo Creek series; magmatism climaxed with main phase magmatism generated within middle continental lithosphere, and then, accompanying regional extension, gradually died out by 18 Ma.

  10. How-To-Do-It: Plant Regeneration.

    Science.gov (United States)

    Pietraface, William J.

    1988-01-01

    Describes a procedure for the growth of tobacco plants in flasks. Demonstrates plant tissue culture manipulation, totipotency, and plant regeneration in approximately 12 weeks. Discusses methods, materials, and expected results. (CW)

  11. Platform technologies for tubular organ regeneration.

    Science.gov (United States)

    Basu, Joydeep; Ludlow, John W

    2010-10-01

    As a result of recent successes in regenerative medicine approaches to engineering multiple disparate tubular organs, methodology commonalities are emerging. Principal themes include the importance of a biodegradable scaffold seeded with a population of smooth muscle cells. Such composites trigger a regenerative response following in vivo implantation, resulting in de novo organogenesis. In this review, we examine bladder regeneration as a foundational platform technology to highlight key principles applicable to the regeneration of any tubular organ, and illustrate how these general concepts underlie current strategies to regenerate components of gastrointestinal, vascular, pulmonary and genitourinary systems. We focus on identifying the elements of this platform that have facilitated the transition of tubular organ regeneration from academic proof-of-concept to commercial viability. Copyright © 2010 Elsevier Ltd. All rights reserved.

  12. Grazing management that regenerates ecosystem function and ...

    African Journals Online (AJOL)

    Grazing management that regenerates ecosystem function and grazingland livelihoods. ... on real operations, applying adaptive treatments, and combining field studies with modelling approaches. Keywords: ecosystem services, management research, regenerative agriculture, simulation modelling, systems research ...

  13. A neonatal blueprint for cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Enzo R. Porrello

    2014-11-01

    Full Text Available Adult mammals undergo minimal regeneration following cardiac injury, which severely compromises cardiac function and contributes to the ongoing burden of heart failure. In contrast, the mammalian heart retains a transient capacity for cardiac regeneration during fetal and early neonatal life. Recent studies have established the importance of several evolutionarily conserved mechanisms for heart regeneration in lower vertebrates and neonatal mammals including induction of cardiomyocyte proliferation, epicardial cell activation, angiogenesis, extracellular matrix deposition and immune cell infiltration. In this review, we provide an up-to-date account of the molecular and cellular basis for cardiac regeneration in lower vertebrates and neonatal mammals. The historical context for these recent findings and their ramifications for the future development of cardiac regenerative therapies are also discussed.

  14. In vitro regeneration in Allium species.

    Science.gov (United States)

    Rauber, M; Grunewaldt, J

    1988-10-01

    An attempt to induce shoot regeneration from leaf disc explants from Allium sativum L., A. porrum L., and A. schoenoprasum L. and the induction of shoot regeneration from single flower-bud receptacles in A. porrum is presented. While the regeneration rate from leaf disc explants was low, an efficient method for propagating A. porrum in vitro was obtained by cultivating single flower-bud receptacles. The shoot regeneration ability was strongly controlled by the genotype. Up to 294 shoots per leek plant could be harvested. Simultaneously the same plant could be used for seed production and bulbil formation in vivo. The efficiency of the in vitro multiplication method described allows the integration of this procedure into breeding programmes of A. porrum.

  15. Advanced Engineering Strategies for Periodontal Complex Regeneration

    Directory of Open Access Journals (Sweden)

    Chan Ho Park

    2016-01-01

    Full Text Available The regeneration and integration of multiple tissue types is critical for efforts to restore the function of musculoskeletal complex. In particular, the neogenesis of periodontal constructs for systematic tooth-supporting functions is a current challenge due to micron-scaled tissue compartmentalization, oblique/perpendicular orientations of fibrous connective tissues to the tooth root surface and the orchestration of multiple regenerated tissues. Although there have been various biological and biochemical achievements, periodontal tissue regeneration remains limited and unpredictable. The purpose of this paper is to discuss current advanced engineering approaches for periodontal complex formations; computer-designed, customized scaffolding architectures; cell sheet technology-based multi-phasic approaches; and patient-specific constructs using bioresorbable polymeric material and 3-D printing technology for clinical application. The review covers various advanced technologies for periodontal complex regeneration and state-of-the-art therapeutic avenues in periodontal tissue engineering.

  16. Pore structure of natural and regenerated soil aggregates

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Arthur, Emmanuel; de Jonge, Lis Wollesen

    2014-01-01

    Quantitative characterization of aggregate pore structure can reveal the evolution of aggregates under different land use and management practices and their effects on soil processes and functions. Advances in X-ray Computed Tomography (CT) provide powerful means to conduct such characterization....... This study examined aggregate pore structure of three differently managed same textured Danish soils (mixed forage cropping, MFC; mixed cash cropping, MCC; cereal cash cropping, CCC) for (i) natural aggregates, and (ii) aggregates regenerated after 20 months of incubation. In total, 27 aggregates (8-16 mm......) were sampled from nine different treatments; 3 natural soils and 3 repacked lysimeters without and 3 with organic matter (ground rape) amendment. Three dimensional X-ray CT images, tensile strength, and organic carbon were obtained for each aggregate. Aggregate-associated organic carbon differed...

  17. Regeneration in Echinoderms: repair, regrowth, cloning

    OpenAIRE

    MD Candia Carnevali

    2006-01-01

    Regenerative potential is expressed to a maximum extent in echinoderms. It is a commonphenomenon in all the classes, extensively employed to reconstruct external appendages and internalorgans often subjected to amputation, self-induced or traumatic, rapidly followed by completesuccessful re-growth of the lost parts. Regeneration has been studied in adult individuals as well as inlarvae. In armed echinoderms, regeneration of arms is obviously frequent: in many cases, thedetached body fragments...

  18. Proteomics based approach to understand tissue regeneration

    OpenAIRE

    Franco, Catarina de Matos Ferraz

    2011-01-01

    Dissertation presented to obtain the PhD degree in Biochemistry Most echinoderm species share an outstanding capacity for regeneration that is maintained throughout the adult animal lifespan. Regeneration allows these deuterostomes to recover from predation injuries or selfinduced arm autotomy, which are known to occur frequently in nature. Although echinoderms are extremely interesting in terms of their phylogenetic proximity to chordates, most areas of echinoderm research have b...

  19. Advanced tissue engineering in periodontal Regeneration

    OpenAIRE

    Seyed Ali Banihashemrad

    2014-01-01

    The old wishes of people were to regenerate lost tissues of periodontium that this fact is achieved by gen and cell therapy .Periodontal disease is a chronic inflammation around the tooth by microbes that causes destruction of supporting structure of tissue of tooth such as alveolar bone, cementum and periodontal ligament. For treatment of periodontal diseases we can use the biomaterials which help to regenerate the periodontal tissues like; autogenous bone grafts, allograft, guided tissue re...

  20. Emdogain--periodontal regeneration based on biomimicry.

    Science.gov (United States)

    Gestrelius, S; Lyngstadaas, S P; Hammarström, L

    2000-06-01

    Biomimicry has been introduced as a term for innovations inspired by nature [1]. Such innovations may appear in almost every part of modern society. This review on the effects of enamel matrix proteins on the formation of cementum and the development of emdogain for regeneration of periodontal tissues lost due to periodontitis shows an example of biomimicry in dentistry. Findings from clinical and laboratory investigations are summarized and the biological basis for enamel matrix-induced periodontal regeneration is discussed.

  1. Continuous microwave regeneration apparatus for absorption media

    Science.gov (United States)

    Smith, Douglas D.

    1999-01-01

    A method and apparatus for continuously drying and regenerating ceramic beads for use in process gas moisture drying operations such as glove boxes. A microwave energy source is coupled to a process chamber to internally heat the ceramic beads and vaporize moisture contained therein. In a preferred embodiment, the moisture laden ceramic beads are conveyed toward the microwave source by a screw mechanism. The regenerated beads flow down outside of the screw mechanism and are available to absorb additional moisture.

  2. Abiotic factors influencing tropical dry forests regeneration

    Directory of Open Access Journals (Sweden)

    Ceccon Eliane

    2006-01-01

    Full Text Available Tropical dry forests represent nearly half the tropical forests in the world and are the ecosystems registering the greatest deterioration from the anthropogenic exploitation of the land. This paper presents a review on the dynamics of tropical dry forests regeneration and the main abiotic factors influencing this regeneration, such as seasonal nature, soil fertility and humidity, and natural and anthropic disturbances. The main purpose is to clearly understand an important part of TDF succession dynamics.

  3. Advanced Engineering Strategies for Periodontal Complex Regeneration

    OpenAIRE

    Chan Ho Park; Kyoung-Hwa Kim; Yong-Moo Lee; Yang-Jo Seol

    2016-01-01

    The regeneration and integration of multiple tissue types is critical for efforts to restore the function of musculoskeletal complex. In particular, the neogenesis of periodontal constructs for systematic tooth-supporting functions is a current challenge due to micron-scaled tissue compartmentalization, oblique/perpendicular orientations of fibrous connective tissues to the tooth root surface and the orchestration of multiple regenerated tissues. Although there have been various biological an...

  4. Adhesive organ regeneration in Macrostomum lignano.

    Science.gov (United States)

    Lengerer, Birgit; Hennebert, Elise; Flammang, Patrick; Salvenmoser, Willi; Ladurner, Peter

    2016-06-02

    Flatworms possess pluripotent stem cells that can give rise to all cell types, which allows them to restore lost body parts after injury or amputation. This makes flatworms excellent model systems for studying regeneration. In this study, we present the adhesive organs of a marine flatworm as a simple model system for organ regeneration. Macrostomum lignano has approximately 130 adhesive organs at the ventral side of its tail plate. One adhesive organ consists of three interacting cells: one adhesive gland cell, one releasing gland cell, and one modified epidermal cell, called an anchor cell. However, no specific markers for these cell types were available to study the regeneration of adhesive organs. We tested 15 commercially available lectins for their ability to label adhesive organs and found one lectin (peanut agglutinin) to be specific to adhesive gland cells. We visualized the morphology of regenerating adhesive organs using lectin- and antibody staining as well as transmission electron microscopy. Our findings indicate that the two gland cells differentiate earlier than the connected anchor cells. Using EdU/lectin staining of partially amputated adhesive organs, we showed that their regeneration can proceed in two ways. First, adhesive gland cell bodies are able to survive partial amputation and reconnect with newly formed anchor cells. Second, adhesive gland cell bodies are cleared away, and the entire adhesive organ is build anew. Our results provide the first insights into adhesive organ regeneration and describe ten new markers for differentiated cells and tissues in M. lignano. The position of adhesive organ cells within the blastema and their chronological differentiation have been shown for the first time. M. lignano can regenerate adhesive organs de novo but also replace individual anchor cells in an injured organ. Our findings contribute to a better understanding of organogenesis in flatworms and enable further molecular investigations of cell

  5. Reptile scale paradigm: Evo-Devo, pattern formation and regeneration

    Science.gov (United States)

    Chang, Cheng; Wu, Ping; Baker, Ruth E.; Maini, Philip K.; Alibardi, Lorenzo; Chuong, Cheng-Ming

    2010-01-01

    The purpose of this perspective is to highlight the merit of the reptile integument as an experimental model. Reptiles represent the first amniotes. From stem reptiles, extant reptiles, birds and mammals have evolved. Mammal hairs and feathers evolved from Therapsid and Sauropsid reptiles, respectively. The early reptilian integument had to adapt to the challenges of terrestrial life, developing a multi-layered stratum corneum capable of barrier function and ultraviolet protection. For better mechanical protection, diverse reptilian scale types have evolved. The evolution of endothermy has driven the convergent evolution of hair and feather follicles: both form multiple localized growth units with stem cells and transient amplifying cells protected in the proximal follicle. This topological arrangement allows them to elongate, molt and regenerate without structural constraints. Another unique feature of reptile skin is the exquisite arrangement of scales and pigment patterns, making them testable models for mechanisms of pattern formation. Since they face the constant threat of damage on land, different strategies were developed to accommodate skin homeostasis and regeneration. Temporally, they can be under continuous renewal or sloughing cycles. Spatially, they can be diffuse or form discrete localized growth units (follicles). To understand how gene regulatory networks evolved to produce increasingly complex ectodermal organs, we have to study how prototypic scale-forming pathways in reptiles are modulated to produce appendage novelties. Despite the fact that there are numerous studies of reptile scales, molecular analyses have lagged behind. Here, we underscore how further development of this novel experimental model will be valuable in filling the gaps of our understanding of the Evo-Devo of amniote integuments. PMID:19557687

  6. Guided tissue regeneration in periapical surgery.

    Science.gov (United States)

    Lin, Louis; Chen, Melody Y-H; Ricucci, Domenico; Rosenberg, Paul A

    2010-04-01

    Tissue regeneration by using membrane barriers and bone grafting materials in periapical surgery is an example of tissue engineering technology. Membrane barriers and/or bone grafts are often used to enhance periapical new bone formation. However, the periapical tissues also consist of the periodontal ligament (PDL) and cementum. For regeneration of the periapical tissues after periapical surgery, one of the important requirements is recruitment and differentiation of progenitor/stem cells into committed pre-osteoblasts, pre-PDL cells, and pre-cementoblasts. Homing of progenitor/stem cells into the wounded periapical tissues is regulated by factors such as stromal cell-derived factor 1, growth factors/cytokines, and by microenvironmental cues such as adhesion molecules and extracellular matrix and associated noncollagenous molecules. Tissue regeneration after injury appears to recapitulate the pathway of normal embryonic tissue development. Multiple tissue regeneration involves a complex interaction between different cells, extracellular matrix, growth/differentiation factors, and microenvironmental cues. Little is known concerning the biologic mechanisms that regulate temporal and spatial relationship between alveolar bone, PDL, and cementum regeneration during periapical wound healing. Simply applying a membrane barrier and/or bone graft during periapical surgery might not result in complete regeneration of the periapical tissues. It has not been clearly demonstrated that these biomaterials are capable of recruiting progenitor/stem cells and inducing these undifferentiated mesenchymal cells to differentiate into PDL cells and cementoblasts after periapical surgery. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Silymarin Accelerates Liver Regeneration after Partial Hepatectomy

    Directory of Open Access Journals (Sweden)

    Jia-Ping Wu

    2015-01-01

    Full Text Available Partial hepatectomy (PHx is a liver regeneration physiological response induced to maintain homeostasis. Liver regeneration evolved presumably to protect wild animals from catastrophic liver loss caused by toxins or tissue injury. Silymarin (Sm ability to stimulate liver regeneration has been an object of curiosity for many years. Silymarin has been investigated for use as an antioxidant and anticarcinogen. However, its use as a supportive treatment for liver damage is elusive. In this study, we fed silymarin (Sm, 25 mg/kg to male Sprague-Dawley rats for 7 weeks. Surgical 2/3 PHx was then conducted on the rats at 6 hrs, 24 hrs, and 72 hrs. Western blot and RT-PCR were conducted to detect the cell cycle activities and silymarin effects on hepatic regeneration. The results showed that silymarin enhanced liver regeneration by accelerating the cell cycle in PHx liver. Silymarin led to increased G1 phase (cyclin D1/pRb, S phase (cyclin E/E2F, G2 phase (cyclin B, and M phase (cyclin A protein and mRNA at 6 hrs, 24 hrs, and 72 hrs PHx. HGF, TGFα, and TGFβ1 growth factor expressions were also enhanced. We suggest that silymarin plays a crucial role in accelerated liver regeneration after PHx.

  8. Promoting tissue regeneration by modulating the immune system.

    Science.gov (United States)

    Julier, Ziad; Park, Anthony J; Briquez, Priscilla S; Martino, Mikaël M

    2017-04-15

    The immune system plays a central role in tissue repair and regeneration. Indeed, the immune response to tissue injury is crucial in determining the speed and the outcome of the healing process, including the extent of scarring and the restoration of organ function. Therefore, controlling immune components via biomaterials and drug delivery systems is becoming an attractive approach in regenerative medicine, since therapies based on stem cells and growth factors have not yet proven to be broadly effective in the clinic. To integrate the immune system into regenerative strategies, one of the first challenges is to understand the precise functions of the different immune components during the tissue healing process. While remarkable progress has been made, the immune mechanisms involved are still elusive, and there is indication for both negative and positive roles depending on the tissue type or organ and life stage. It is well recognized that the innate immune response comprising danger signals, neutrophils and macrophages modulates tissue healing. In addition, it is becoming evident that the adaptive immune response, in particular T cell subset activities, plays a critical role. In this review, we first present an overview of the basic immune mechanisms involved in tissue repair and regeneration. Then, we highlight various approaches based on biomaterials and drug delivery systems that aim at modulating these mechanisms to limit fibrosis and promote regeneration. We propose that the next generation of regenerative therapies may evolve from typical biomaterial-, stem cell-, or growth factor-centric approaches to an immune-centric approach. Most regenerative strategies have not yet proven to be safe or reasonably efficient in the clinic. In addition to stem cells and growth factors, the immune system plays a crucial role in the tissue healing process. Here, we propose that controlling the immune-mediated mechanisms of tissue repair and regeneration may support

  9. Tissue Regeneration: A Silk Road.

    Science.gov (United States)

    Jao, Dave; Mou, Xiaoyang; Hu, Xiao

    2016-08-05

    Silk proteins are natural biopolymers that have extensive structural possibilities for chemical and mechanical modifications to facilitate novel properties, functions, and applications in the biomedical field. The versatile processability of silk fibroins (SF) into different forms such as gels, films, foams, membranes, scaffolds, and nanofibers makes it appealing in a variety of applications that require mechanically superior, biocompatible, biodegradable, and functionalizable biomaterials. There is no doubt that nature is the world's best biological engineer, with simple, exquisite but powerful designs that have inspired novel technologies. By understanding the surface interaction of silk materials with living cells, unique characteristics can be implemented through structural modifications, such as controllable wettability, high-strength adhesiveness, and reflectivity properties, suggesting its potential suitability for surgical, optical, and other biomedical applications. All of the interesting features of SF, such as tunable biodegradation, anti-bacterial properties, and mechanical properties combined with potential self-healing modifications, make it ideal for future tissue engineering applications. In this review, we first demonstrate the current understanding of the structures and mechanical properties of SF and the various functionalizations of SF matrices through chemical and physical manipulations. Then the diverse applications of SF architectures and scaffolds for different regenerative medicine will be discussed in detail, including their current applications in bone, eye, nerve, skin, tendon, ligament, and cartilage regeneration.

  10. Clinical advances in bone regeneration.

    Science.gov (United States)

    Siddiqui, Nashat A; Owen, John M

    2013-05-01

    Understanding of the biology of bone regeneration has been increasing rapidly, with greater appreciation for the importance of biochemical aspects as well as the mechanical requirements for bone to heal. There are a number of situations where there is difficulty in bone healing such as fracture non-union; or growth such as osteogenesis imperfecta; or a requirement for surplus bone to reconstruct defects such as following surgery for tumour excision or limb lengthening. There is a greater understanding of the complex interplay between osteoblasts and osteoclasts, and the chemical mediators that provide signalling along complex pathways. Although we have known about substances such as Bone Morphogenic Proteins and Growth Hormones for some time, their application in clinical practice is still not widespread, and we need to study them more to understand their role in bone healing. With newer technologies such as stem cells and gene therapy being developed there is the potential for vast improvement in bone regenerative techniques, although we are not at a stage where we can be confident that these techniques will work. In this review article we discuss the basic healing process of bone and how our understanding of this has led to improved techniques as well as the potential for future developments in new technologies.

  11. Modelling and simulation of regenerators with complex flow arrangements for active magnetocaloric refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

    2014-01-01

    Compared to a conventional vapor compression refrigera-tion system, a magnetocaloric refrigerator has many advantages, such as potentially high efficiency, low vibration and avoidance of refrigerants that deplete the ozone layer and cause the green-house effect. As a main component of the active...... magnetic re-generative refrigerator, the regenerator plays an important role in the cooling performance and efficiency of the whole system. However, the regenerator design is constrained by several exter-nal factors, such as the geometry of the magnetic field source and flow resistance. In this work, novel...

  12. Teaching Evolution

    Science.gov (United States)

    Bryner, Jeanna

    2005-01-01

    Eighty years after the famous 1925 Scopes "monkey trial," which tested a teacher's right to discuss the theory of evolution in the classroom, evolution--and its most recent counterview, called "intelligent design"--are in the headlines again, and just about everyone seems to have an opinion. This past July, President Bush weighed in, telling…

  13. The cancer paradigms of mammalian regeneration: can mammals regenerate as amphibians?

    Science.gov (United States)

    Sarig, Rachel; Tzahor, Eldad

    2017-04-01

    Regeneration in mammals is restricted to distinct tissues and occurs mainly by expansion and maturation of resident stem cells. During regeneration, even subtle mutations in the proliferating cells may cause a detrimental effect by eliciting abnormal differentiation or malignant transformation. Indeed, cancer in mammals has been shown to arise through deregulation of stem cells maturation, which often leads to a differentiation block and cell transformation. In contrast, lower organisms such as amphibians retain a remarkable regenerative capacity in various organs, which occurs via de- and re-differentiation of mature cells. Interestingly, regenerating amphibian cells are highly resistant to oncogenic transformation. Therapeutic approaches to improve mammalian regeneration mainly include stem-cell transplantations; but, these have proved unsuccessful in non-regenerating organs such as the heart. A recently developed approach is to induce de-differentiation of mature cardiomyocytes using factors that trigger their re-entry into the cell cycle. This novel approach raises numerous questions regarding the balance between transformation and regeneration induced by de-differentiation of mature mammalian somatic cells. Can this balance be controlled artificially? Do de-differentiated cells acquire the protection mechanisms seen in regenerating cells of lower organisms? Is this model unique to the cardiac tissue, which rarely develops tumors? This review describes regeneration processes in both mammals and lower organisms and, particularly, the ability of regenerating cells to avoid transformation. By comparing the characteristics of mammalian embryonic and somatic cells, we discuss therapeutic strategies of using various cell populations for regeneration. Finally, we describe a novel cardiac regeneration approach and its implications for regenerative medicine. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email

  14. Sustainable Urban Regeneration Based on Energy Balance

    Directory of Open Access Journals (Sweden)

    Sacha Silvester

    2012-07-01

    Full Text Available In this paper, results are reported of a technology assessment of the use and integration of decentralized energy systems and storage devices in an urban renewal area. First the general context of a different approach based on 'rethinking' and the incorporation of ongoing integration of coming economical and environmental interests on infrastructure, in relation to the sustainable urban development and regeneration from the perspective of the tripod people, technology and design is elaborated. However, this is at different scales, starting mainly from the perspective of the urban dynamics. This approach includes a renewed look at the ‘urban metabolism’ and the role of environmental technology, urban ecology and environment behavior focus. Second, the potential benefits of strategic and balanced introduction and use of decentralized devices and electric vehicles (EVs, and attached generation based on renewables are investigated in more detail in the case study of the ‘Merwe-Vierhaven’ area (MW4 in the Rotterdam city port in the Netherlands. In order to optimize the energy balance of this urban renewal area, it is found to be impossible to do this by tuning the energy consumption. It is more effective to change the energy mix and related infrastructures. However, the problem in existing urban areas is that often these areas are restricted to a few energy sources due to lack of available space for integration. Besides this, energy consumption in most cases is relatively concentrated in (existing urban areas. This limits the potential of sustainable urban regeneration based on decentralized systems, because there is no balanced choice regarding the energy mix based on renewables and system optimization. Possible solutions to obtain a balanced energy profile can come from either the choice to not provide all energy locally, or by adding different types of storage devices to the systems. The use of energy balance based on renewables as a

  15. An improved protocol for efficient transformation and regeneration of diverse indica rice cultivars

    Directory of Open Access Journals (Sweden)

    Sahoo Khirod K

    2011-12-01

    Full Text Available Abstract Background Rice genome sequencing projects have generated remarkable amount of information about genes and genome architecture having tremendous potential to be utilized in both basic and applied research. Success in transgenics is paving the way for preparing a road map of functional genomics which is expected to correlate action of a gene to a trait in cellular and organismal context. However, the lack of a simple and efficient method for transformation and regeneration is a major constraint for such studies in this important cereal crop. Results In the present study, we have developed an easy, rapid and highly efficient transformation and regeneration protocol using mature seeds as explants and found its successful applicability to a choice of elite indica rice genotypes. We have optimized various steps of transformation and standardized different components of the regeneration medium including growth hormones and the gelling agent. The modified regeneration medium triggers production of large number of shoots from smaller number of calli and promotes their faster growth, hence significantly advantageous over the existing protocols where the regeneration step requires maximum time. Using this protocol, significantly higher transformation efficiency (up to 46% and regeneration frequency (up to 92% for the untransformed calli and 59% for the transformed calli were achieved for the four tested cultivars. We have used this protocol to produce hundreds of independent transgenic lines of different indica rice genotypes. Upon maturity, these transgenic lines were fertile thereby indicating that faster regeneration during tissue culture did not affect their reproductive potential. Conclusions This speedy, yet less labor-intensive, protocol overcomes major limitations associated with genetic manipulation in rice. Moreover, our protocol uses mature seeds as the explant, which can easily be obtained in quantity throughout the year and kept

  16. Hydrogels as scaffolds and delivery systems to enhance axonal regeneration after injuries

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    Oscar A. Carballo-Molina

    2015-02-01

    Full Text Available Damage caused to neural tissue by disease or injury frequently produces a discontinuity in the nervous system. Such damage generates diverse alterations that are commonly permanent, due to the limited regeneration capacity of the adult nervous system, particularly the Central Nervous System (CNS. The cellular reaction to noxious stimulus leads to several events such as the formation of glial and fibrous scars, which inhibit axonal regeneration in both the CNS and the Peripheral Nervous System (PNS. Although in the PNS there is some degree of nerve regeneration, it is common that the growing axons reinnervate incorrect areas, causing mismatches. Providing a permissive substrate for axonal regeneration in combination with delivery systems for the release of molecules, which enhances axonal growth, could increase regeneration and the recovery of functions in the CNS or the PNS. Currently, there are no effective vehicles to supply growth factors or cells to the damaged/diseased nervous system. Hydrogels are polymers that are biodegradable, biocompatible and have the capacity to deliver a large range of molecules in situ. The inclusion of cultured neural cells into hydrogels forming three-dimensional structures allows the formation of synapses and neuronal survival. There is also evidence showing that hydrogels constitute an amenable substrate for axonal growth of endogenous or grafted cells, overcoming the presence of axonal regeneration inhibitory molecules, in both the central and peripheral nervous systems. Recent experiments suggest that hydrogels can carry and deliver several proteins relevant for improving neuronal survival and axonal growth. Although the use of hydrogels is appealing, its effectiveness is still a matter of discussion, and more results are needed to achieve consistent recovery using different parameters. This review also discusses areas of opportunity where hydrogels can be applied, in order to promote axonal regeneration of

  17. [Molecular mechanism of brain regeneration and reconstruction of dopaminergic neural network in planarians].

    Science.gov (United States)

    Nishimura, Kaneyasu; Kitamura, Yoshihisa; Agata, Kiyokazu

    2008-04-01

    Recently, planarians have received much attention because of their contributions to research on the basic science of stem cell systems, neural regeneration, and regenerative medicine. Planarians can regenerate complete organs, including a well-organized central nervous system (CNS), within about 7 days. This high regenerative capacity is supported by pluripotent stem cells present in the mesenchymal space throughout the body. Interestingly, planarians can regenerate their brain via a molecular mechanism similar to that of mammalian brain development. The regeneration process of the planarian brain can be divided into five steps: (1) anterior blastema formation, (2) brain rudiment formation, (3) brain pattern formation, (4) neural network formation, and (5) functional recovery, with several kinds of genes and molecular cascades acting at each step. Recently, we have identified a planarian tyrosine hydroxylase (TH) gene, a rate-limiting enzyme for dopamine (DA) biosynthesis, and produced TH-knockdown planarians by the RNA interference technique. Studies of TH-knockdown planarians showed that DA has an important role of the modification in behavioral movement in planarians. Using monoclonal anti-planarian TH antibody, we also found that dopaminergic neurons are mainly localized in the planarian brain. When the planarian body was amputated, newly generated TH-immunopositive neurons were detected in the anterior region at day 3 of regeneration (i.e., the period of neural network formation), and the TH-immunopositive axonal and dendritic neural network in the CNS was reconstructed during day 5-7 of regeneration. In this article, recent advances in elucidating the molecular mechanism of planarian brain regeneration and dopaminergic neurons are reviewed, and its future prospects for contribution of this system to basic science and medical science research are described.

  18. Functional Regeneration Following Spinal Transection Demonstrated in the Isolated Spinal Cord of the Larval Sea Lamprey

    Science.gov (United States)

    Cohen, A. H.; Mackler, S. A.; Selzer, M. E.

    1986-04-01

    Axons in the larval sea lamprey can regenerate across the site of a spinal cord transection and form functioning synapses with some of their normal target neurons. The animals recover normal-appearing locomotion, but whether the regenerating axons and their synaptic connections are capable of playing a functional role during this behavior is unknown. To test this, ``fictive'' swimming was induced in the isolated spinal cord by the addition of D-glutamate to the bathing solution. Ventral root discharges of segments above and below a healed transection showed a high degree of phase-locking. This strongly suggests that the behavioral recovery is mediated by regenerated functional synaptic connections subserving intersegmental coordination of the central pattern generator for locomotion.

  19. Concise Review: Regeneration in Mammalian Cochlea Hair Cells: Help from Supporting Cells Transdifferentiation.

    Science.gov (United States)

    Franco, Bénédicte; Malgrange, Brigitte

    2017-03-01

    It is commonly assumed that mammalian cochlear cells do not regenerate. Therefore, if hair cells are lost following an injury, no recovery could occur. However, during the first postnatal week, mice harbor some progenitor cells that retain the ability to give rise to new hair cells. These progenitor cells are in fact supporting cells. Upon hair cells loss, those cells are able to generate new hair cells both by direct transdifferentiation or following cell cycle re-entry and differentiation. However, this property of supporting cells is progressively lost after birth. Here, we review the molecular mechanisms that are involved in mammalian hair cell development and regeneration. Manipulating pathways used during development constitute good candidates for inducing hair cell regeneration after injury. Despite these promising studies, there is still no evidence for a recovery following hair cells loss in adult mammals. Stem Cells 2017;35:551-556. © 2017 AlphaMed Press.

  20. CALLUS FORMATION AND REGENERATION OF Deschampsia antarctica Desv. (Poaceae IN CULTURE in vitro

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    О. M. Zagrychuk

    2013-12-01

    Full Text Available Conditions for induction of callus formation from root and stem explants and long-term maintenance of Deschampsia antarctica Desv. Tissue culture have been specified. Ability to callus formation depended on mineral composition of nutrient medium, combination of growth regulator concentrations, place of donor-plant vegetation and type of explant. The optimal for callus tissue generation was Gamborg, Eveleigh — B5 nutrient medium, supplemented with 0.9–1.0 mg/l 2.4-dichlorophenyl acetic acid and 0.09–0.1 mg/l of cytokinine benzylaminopurine. Callus formation potency from the root explants considerably exceeded (1.5–2 times that of from stem ones. The shoots were derived through spontaneous indirect organogenesis. Regeneration efficiency was found to be affected by nutrient medium composition and callus origin. Regenerated shoots were rooted and conditions for growth of regenerated plants in vitro were specified.

  1. A Study of Regenerator for a Personal Stirling Refrigerator

    Science.gov (United States)

    Murakami, Kazuhiko; Otaka, Toshio; Sakamoto, Moriyoshi; Yamaguchi, Hajime; Ota, Masahiro

    Stirling cycle system is expected as a gentle system to the earth, because the working fluid is completely free from chlorine molecules. A regenerator is the most important element of the Stirling cycle system for the performances. Flow in a regenerator is very complicated because the regenerator is made of matrix. So we are studying about Stirling cycle systems, especially the regenerator for a personal Stirling refrigerator. In this report, flow in a regenerator for a personal Stirling refrigerators is studied by using an original experimental set-up. Flow velocities and pressures at the outside of a matrix in a regenerator were measured in a round pipe. Flow effects of inlet or outlet shape and area for a regenerator were examined in detail. Pressure loss were measured at sides of a regenerator and friction factors were expressed as empirical formulas for each conditions of inlet shape of regenerator or matrixes.

  2. Mechanisms of lymphatic regeneration after tissue transfer.

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    Alan Yan

    2011-02-01

    Full Text Available Lymphedema is the chronic swelling of an extremity that occurs commonly after lymph node resection for cancer treatment. Recent studies have demonstrated that transfer of healthy tissues can be used as a means of bypassing damaged lymphatics and ameliorating lymphedema. The purpose of these studies was to investigate the mechanisms that regulate lymphatic regeneration after tissue transfer.Nude mice (recipients underwent 2-mm tail skin excisions that were either left open or repaired with full-thickness skin grafts harvested from donor transgenic mice that expressed green fluorescent protein in all tissues or from LYVE-1 knockout mice. Lymphatic regeneration, expression of VEGF-C, macrophage infiltration, and potential for skin grafting to bypass damaged lymphatics were assessed.Skin grafts healed rapidly and restored lymphatic flow. Lymphatic regeneration occurred beginning at the peripheral edges of the graft, primarily from ingrowth of new lymphatic vessels originating from the recipient mouse. In addition, donor lymphatic vessels appeared to spontaneously re-anastomose with recipient vessels. Patterns of VEGF-C expression and macrophage infiltration were temporally and spatially associated with lymphatic regeneration. When compared to mice treated with excision only, there was a 4-fold decrease in tail volumes, 2.5-fold increase in lymphatic transport by lymphoscintigraphy, 40% decrease in dermal thickness, and 54% decrease in scar index in skin-grafted animals, indicating that tissue transfer could bypass damaged lymphatics and promote rapid lymphatic regeneration.Our studies suggest that lymphatic regeneration after tissue transfer occurs by ingrowth of lymphatic vessels and spontaneous re-connection of existing lymphatics. This process is temporally and spatially associated with VEGF-C expression and macrophage infiltration. Finally, tissue transfer can be used to bypass damaged lymphatics and promote rapid lymphatic regeneration.

  3. Dental pulp regeneration via cell homing.

    Science.gov (United States)

    Eramo, S; Natali, A; Pinna, R; Milia, E

    2017-10-19

    The typical treatment for irreversibly inflamed/necrotic pulp tissue is root canal treatment. As an alternative approach, regenerative endodontics aims to regenerate dental pulp-like tissues using two possible strategies: cell transplantation and cell homing. The former requires exogenously transplanted stem cells, complex procedures and high costs; the latter employs the host's endogenous cells to achieve tissue repair/regeneration, which is more clinically translatable. This systematic review examines cell homing for dental pulp regeneration, selecting articles on in vitro experiments, in vivo ectopic transplantation models and in situ pulp revascularization. MEDLINE/PubMed and Scopus databases were electronically searched for articles without limits in publication date. Two reviewers independently screened and included papers according to the predefined selection criteria. The electronic searches identified 46 studies. After title, abstract and full-text examination, 10 articles met the inclusion criteria. In vitro data highlighted that multiple cytokines have the capacity to induce migration, proliferation and differentiation of dental pulp stem/progenitor cells. The majority of the in vivo studies obtained regenerated connective pulp-like tissues with neovascularization. In some cases, the samples showed new innervation and new dentine deposition. The in situ pulp revascularization regenerated intracanal pulp-like tissues with neovascularization, innervation and dentine formation. Cell homing strategies for pulp regeneration need further understanding and improvement if they are to become a reliable and effective approach in endodontics. Nevertheless, cell homing currently represents the most clinically viable pathway for dental pulp regeneration. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  4. Differential expression of HDACs and KATs in high and low regeneration capacity neurons during spinal cord regeneration.

    Science.gov (United States)

    Chen, Jie; Laramore, Cindy; Shifman, Michael I

    2016-06-01

    After spinal cord injury (SCI) in mammals, injured axons fail to regenerate. By contrast, lampreys recover from complete spinal transection and axons regenerate selectively in their correct paths. Yet the large, identified reticulospinal neurons in the lamprey brain vary greatly in their regenerative abilities - some have high regeneration capacity (probability of regeneration >50%) and others have low regeneration capacity (regenerating and non-regenerating neurons located in the same brain region and projecting to the same axon tracts suggests that differences in their regenerating abilities depend upon factors intrinsic to the neurons. Previous work has suggested that axon regeneration, especially in PNS, could depend on epigenetic mechanisms of histone modifications, such as the acetylation of histone tails. Our data indicated that expression of the enzymes responsible for regulating the acetylation of histone (KATs and HDACs) - KAT2A, KAT5 and P300 and HDAC3 did not change after SCI in either high regeneration capacity or low regeneration capacity neurons. In the present report, we show a novel and unexpected relationship between neuron regeneration abilities and expression of HDAC1. While HDAC1 expression was downregulated in both high and low regeneration capacity neurons 2 and 4weeks after SCI, it was upregulated at 7weeks at almost all RS neurons. However, at 10weeks post-transection only high regeneration capacity neurons displayed elevated HDAC1 mRNA expression and HDAC1 expression was again downregulated in low regeneration capacity neurons. Moreover, we show that HDAC1 is preferentially expressed in regenerated neurons, but not in non-regenerating neurons. Together, these results suggest that SCI causes significant changes in HDAC1 expression and that HDAC1 expression in regenerating neurons may modulates a survival or regeneration programs. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Stem cell-based growth, regeneration, and remodeling of the planarian intestine

    Science.gov (United States)

    Forsthoefel, David J.; Park, Amanda E.; Newmark, Phillip A.

    2011-01-01

    Although some animals are capable of regenerating organs, the mechanisms by which this is achieved are poorly understood. In planarians, pluripotent somatic stem cells called neoblasts supply new cells for growth, replenish tissues in response to cellular turnover, and regenerate tissues after injury. For most tissues and organs, however, the spatiotemporal dynamics of stem cell differentiation and the fate of tissue that existed prior to injury have not been characterized systematically. Utilizing in vivo imaging and bromodeoxyuridine pulse-chase experiments, we have analyzed growth and regeneration of the planarian intestine, the organ responsible for digestion and nutrient distribution. During growth, we observe that new gut branches are added along the entire anteroposterior axis. We find that new enterocytes differentiate throughout the intestine rather than in specific growth zones, suggesting that branching morphogenesis is achieved primarily by remodeling of differentiated intestinal tissues. During regeneration, we also demonstrate a previously unappreciated degree of intestinal remodeling, in which pre-existing posterior gut tissue contributes extensively to the newly formed anterior gut, and vice versa. By contrast to growing animals, differentiation of new intestinal cells occurs at preferential locations, including within newly generated tissue (the blastema), and along pre-existing intestinal branches undergoing remodeling. Our results indicate that growth and regeneration of the planarian intestine are achieved by coordinated differentiation of stem cells and the remodeling of pre-existing tissues. Elucidation of the mechanisms by which these processes are integrated will be critical for understanding organogenesis in a post-embryonic context. PMID:21664348

  6. Functional tooth restoration by allogeneic mesenchymal stem cell-based bio-root regeneration in swine.

    Science.gov (United States)

    Wei, Fulan; Song, Tieli; Ding, Gang; Xu, Junji; Liu, Yi; Liu, Dayong; Fan, Zhipeng; Zhang, Chunmei; Shi, Songtao; Wang, Songlin

    2013-06-15

    Our previous proof-of-concept study showed the feasibility of regenerating the dental stem cell-based bioengineered tooth root (bio-root) structure in a large animal model. Here, we used allogeneic dental mesenchymal stem cells to regenerate bio-root, and then installed a crown on the bio-root to restore tooth function. A root shape hydroxyapatite tricalcium phosphate scaffold containing dental pulp stem cells was covered by a Vc-induced periodontal ligament stem cell sheet and implanted into a newly generated jaw bone implant socket. Six months after implantation, a prefabricated porcelain crown was cemented to the implant and subjected to tooth function. Clinical, radiological, histological, ultrastructural, systemic immunological evaluations and mechanical properties were analyzed for dynamic changes in the bio-root structure. The regenerated bio-root exhibited characteristics of a normal tooth after 6 months of use, including dentinal tubule-like and functional periodontal ligament-like structures. No immunological response to the bio-roots was observed. We developed a standard stem cell procedure for bio-root regeneration to restore adult tooth function. This study is the first to successfully regenerate a functional bio-root structure for artificial crown restoration by using allogeneic dental stem cells and Vc-induced cell sheet, and assess the recipient immune response in a preclinical model.

  7. The axolotl limb blastema: cellular and molecular mechanisms driving blastema formation and limb regeneration in tetrapods

    Science.gov (United States)

    McCusker, Catherine; Bryant, Susan V.

    2015-01-01

    Abstract The axolotl is one of the few tetrapods that are capable of regenerating complicated biological structures, such as complete limbs, throughout adulthood. Upon injury the axolotl generates a population of regeneration‐competent limb progenitor cells known as the blastema, which will grow, establish pattern, and differentiate into the missing limb structures. In this review we focus on the crucial early events that occur during wound healing, the neural−epithelial interactions that drive the formation of the early blastema, and how these mechanisms differ from those of other species that have restricted regenerative potential, such as humans. We also discuss how the presence of cells from the different axes of the limb is required for the continued growth and establishment of pattern in the blastema as described in the polar coordinate model, and how this positional information is reprogrammed in blastema cells during regeneration. Multiple cell types from the mature limb stump contribute to the blastema at different stages of regeneration, and we discuss the contribution of these types to the regenerate with reference to whether they are “pattern‐forming” or “pattern‐following” cells. Lastly, we explain how an engineering approach will help resolve unanswered questions in limb regeneration, with the goal of translating these concepts to developing better human regenerative therapies. PMID:27499868

  8. dlx and sp6-9 Control optic cup regeneration in a prototypic eye.

    Directory of Open Access Journals (Sweden)

    Sylvain W Lapan

    2011-08-01

    Full Text Available Optic cups are a structural feature of diverse eyes, from simple pit eyes to camera eyes of vertebrates and cephalopods. We used the planarian prototypic eye as a model to study the genetic control of optic cup formation and regeneration. We identified two genes encoding transcription factors, sp6-9 and dlx, that were expressed in the eye specifically in the optic cup and not the photoreceptor neurons. RNAi of these genes prevented formation of visible optic cups during regeneration. Planarian regeneration requires an adult proliferative cell population with stem cell-like properties called the neoblasts. We found that optic cup formation occurred only after migration of progressively differentiating progenitor cells from the neoblast population. The eye regeneration defect caused by dlx and sp6-9 RNAi can be explained by a failure to generate these early optic cup progenitors. Dlx and Sp6-9 genes function as a module during the development of diverse animal appendages, including vertebrate and insect limbs. Our work reveals a novel function for this gene pair in the development of a fundamental eye component, and it utilizes these genes to demonstrate a mechanism for total organ regeneration in which extensive cell movement separates new cell specification from organ morphogenesis.

  9. Engineering Pichia pastoris for improved NADH regeneration: A novel chassis strain for whole-cell catalysis

    Directory of Open Access Journals (Sweden)

    Martina Geier

    2015-09-01

    Full Text Available Many synthetically useful reactions are catalyzed by cofactor-dependent enzymes. As cofactors represent a major cost factor, methods for efficient cofactor regeneration are required especially for large-scale synthetic applications. In order to generate a novel and efficient host chassis for bioreductions, we engineered the methanol utilization pathway of Pichia pastoris for improved NADH regeneration. By deleting the genes coding for dihydroxyacetone synthase isoform 1 and 2 (DAS1 and DAS2, NADH regeneration via methanol oxidation (dissimilation was increased significantly. The resulting Δdas1 Δdas2 strain performed better in butanediol dehydrogenase (BDH1 based whole-cell conversions. While the BDH1 catalyzed acetoin reduction stopped after 2 h reaching ~50% substrate conversion when performed in the wild type strain, full conversion after 6 h was obtained by employing the knock-out strain. These results suggest that the P. pastoris Δdas1 Δdas2 strain is capable of supplying the actual biocatalyst with the cofactor over a longer reaction period without the over-expression of an additional cofactor regeneration system. Thus, focusing the intrinsic carbon flux of this methylotrophic yeast on methanol oxidation to CO2 represents an efficient and easy-to-use strategy for NADH-dependent whole-cell conversions. At the same time methanol serves as co-solvent, inductor for catalyst and cofactor regeneration pathway expression and source of energy.

  10. Fast revascularization of the injured area is essential to support zebrafish heart regeneration.

    Science.gov (United States)

    Marín-Juez, Rubén; Marass, Michele; Gauvrit, Sebastien; Rossi, Andrea; Lai, Shih-Lei; Materna, Stefan C; Black, Brian L; Stainier, Didier Y R

    2016-10-04

    Zebrafish have a remarkable capacity to regenerate their heart. Efficient replenishment of lost tissues requires the activation of different cell types including the epicardium and endocardium. A complex set of processes is subsequently needed to support cardiomyocyte repopulation. Previous studies have identified important determinants of heart regeneration; however, to date, how revascularization of the damaged area happens remains unknown. Here, we show that angiogenic sprouting into the injured area starts as early as 15 h after injury. To analyze the role of vegfaa in heart regeneration, we used vegfaa mutants rescued to adulthood by vegfaa mRNA injections at the one-cell stage. Surprisingly, vegfaa mutants develop coronaries and revascularize after injury. As a possible explanation for these observations, we find that vegfaa mutant hearts up-regulate the expression of potentially compensating genes. Therefore, to overcome the lack of a revascularization phenotype in vegfaa mutants, we generated fish expressing inducible dominant negative Vegfaa. These fish displayed minimal revascularization of the damaged area. In the absence of fast angiogenic revascularization, cardiomyocyte proliferation did not occur, and the heart failed to regenerate, retaining a fibrotic scar. Hence, our data show that a fast endothelial invasion allows efficient revascularization of the injured area, which is necessary to support replenishment of new tissue and achieve efficient heart regeneration. These findings revisit the model where neovascularization is considered to happen concomitant with the formation of new muscle. Our work also paves the way for future studies designed to understand the molecular mechanisms that regulate fast revascularization.

  11. Axon regeneration in C. elegans: Worming our way to mechanisms of axon regeneration.

    Science.gov (United States)

    Byrne, Alexandra B; Hammarlund, Marc

    2017-01-01

    How axons repair themselves after injury is a fundamental question in neurobiology. With its conserved genome, relatively simple nervous system, and transparent body, C. elegans has recently emerged as a productive model to uncover the cellular mechanisms that regulate and execute axon regeneration. In this review, we discuss the strengths and weaknesses of the C. elegans model of regeneration. We explore the technical advances that enable the use of C. elegans for in vivo regeneration studies, review findings in C. elegans that have contributed to our understanding of the regeneration response across species, discuss the potential of C. elegans research to provide insight into mechanisms that function in the injured mammalian nervous system, and present potential future directions of axon regeneration research using C. elegans. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Surface grafting of styrene on polypropylene fibers by argon plasma and its adsorption-regeneration of BTX

    Science.gov (United States)

    Xu, J. J.; Guo, M. L.; Chen, Q. G.; Lian, Z. Y.; Wei, W. J.; Luo, Z. W.; Xie, G.; Chen, H. N.; Dong, K.

    2017-08-01

    Active macromolecular free radicals were generated on polypropylene (PP) fibers surfaces by argon (Ar) plasma irradiation, then, PP surface modified fibers (PP-g-St fibers) were prepared by in-situ grafting reaction of styrene monomers (St). Effects of reaction parameters on grafting percentage were studied and adsorption capacities of PP-g-St fibers for benzene, toluene and xylene (BTX) were evaluated. Afterwards, regeneration adsorption efficiencies after maximum adsorption were explored. The results indicated that the optimum input power, irradiation time and grafting reaction time are 90 W, 3 min and 3 h respectively and the grafting percentage of St reached 5.7 %. The adsorption capacities of PP-g-St fibers towards toluene and xylene emulsions and solutions in water increased by 336.89 % and 344.57 % respectively, compared to pristine PP fibers. In addition, regeneration adsorption efficiencies of modified fibers remained > 90 % after six cycles of regeneration-adsorption experiments, which showed excellent regeneration ability.

  13. Trinity Evolution.

    Science.gov (United States)

    Rush, Shannon M

    2010-06-01

    Trinity Evolution Cryopreserved Cell Viable Bone Matrix is a minimally manipulated, human cellular, and tissue-based allograft containing adult mesenchymal stem cells, osteoprogenitor cells, and a demineralized cortical component. The cancellous bone used to produce Trinity Evolution is derived from freshly recovered donor tissue by Food and Drug Administration-registered facilities and processed under aseptic conditions. Preclinical in vivo and in vitro testing as well as strict donor screening has demonstrated the safety of Trinity Evolution as well as its osteoinductive and osteogenic potential contained within a natural osteoconductive matrix.

  14. Stellar evolution

    CERN Document Server

    Meadows, A J

    2013-01-01

    Stellar Evolution, Second Edition covers the significant advances in the understanding of birth, life, and death of stars.This book is divided into nine chapters and begins with a description of the characteristics of stars according to their brightness, distance, size, mass, age, and chemical composition. The next chapters deal with the families, structure, and birth of stars. These topics are followed by discussions of the chemical composition and the evolution of main-sequence stars. A chapter focuses on the unique features of the sun as a star, including its evolution, magnetic fields, act

  15. Evolution without evolution and without ambiguities

    Science.gov (United States)

    Marletto, C.; Vedral, V.

    2017-02-01

    In quantum theory it is possible to explain time, and dynamics, in terms of entanglement. This is the timeless approach to time, which assumes that the universe is in a stationary state, where two noninteracting subsystems, the "clock" and the "rest," are entangled. As a consequence, by choosing a suitable observable of the clock, the relative state of the rest of the universe evolves unitarily with respect to the variable labeling the clock observable's eigenstates, which is then interpreted as time. This model for an "evolution without evolution" (Page and Wootters, 1983), albeit elegant, has never been developed further, because it was criticized for generating severe ambiguities in the dynamics of the rest of the universe. In this paper we show that there are no such ambiguities; we also update the model, making it amenable to possible new applications.

  16. Radial glial cells play a key role in echinoderm neural regeneration

    Science.gov (United States)

    2013-01-01

    Background Unlike the mammalian central nervous system (CNS), the CNS of echinoderms is capable of fast and efficient regeneration following injury and constitutes one of the most promising model systems that can provide important insights into evolution of the cellular and molecular events involved in neural repair in deuterostomes. So far, the cellular mechanisms of neural regeneration in echinoderm remained obscure. In this study we show that radial glial cells are the main source of new cells in the regenerating radial nerve cord in these animals. Results We demonstrate that radial glial cells of the sea cucumber Holothuria glaberrima react to injury by dedifferentiation. Both glia and neurons undergo programmed cell death in the lesioned CNS, but it is the dedifferentiated glial subpopulation in the vicinity of the injury that accounts for the vast majority of cell divisions. Glial outgrowth leads to formation of a tubular scaffold at the growing tip, which is later populated by neural elements. Most importantly, radial glial cells themselves give rise to new neurons. At least some of the newly produced neurons survive for more than 4 months and express neuronal markers typical of the mature echinoderm CNS. Conclusions A hypothesis is formulated that CNS regeneration via activation of radial glial cells may represent a common capacity of the Deuterostomia, which is not invoked spontaneously in higher vertebrates, whose adult CNS does not retain radial glial cells. Potential implications for biomedical research aimed at finding the cure for human CNS injuries are discussed. PMID:23597108

  17. The human ARF tumor suppressor senses blastema activity and suppresses epimorphic tissue regeneration

    Science.gov (United States)

    Hesse, Robert G; Kouklis, Gayle K; Ahituv, Nadav; Pomerantz, Jason H

    2015-01-01

    The control of proliferation and differentiation by tumor suppressor genes suggests that evolution of divergent tumor suppressor repertoires could influence species’ regenerative capacity. To directly test that premise, we humanized the zebrafish p53 pathway by introducing regulatory and coding sequences of the human tumor suppressor ARF into the zebrafish genome. ARF was dormant during development, in uninjured adult fins, and during wound healing, but was highly expressed in the blastema during epimorphic fin regeneration after amputation. Regenerative, but not developmental signals resulted in binding of zebrafish E2f to the human ARF promoter and activated conserved ARF-dependent Tp53 functions. The context-dependent activation of ARF did not affect growth and development but inhibited regeneration, an unexpected distinct tumor suppressor response to regenerative versus developmental environments. The antagonistic pleiotropic characteristics of ARF as both tumor and regeneration suppressor imply that inducing epimorphic regeneration clinically would require modulation of ARF –p53 axis activation. DOI: http://dx.doi.org/10.7554/eLife.07702.001 PMID:26575287

  18. Iridium-Doped Ruthenium Oxide Catalyst for Oxygen Evolution

    Science.gov (United States)

    Valdez, Thomas I.; Narayan, Sri R.; Billings, Keith J.

    2011-01-01

    NASA requires a durable and efficient catalyst for the electrolysis of water in a polymer-electrolyte-membrane (PEM) cell. Ruthenium oxide in a slightly reduced form is known to be a very efficient catalyst for the anodic oxidation of water to oxygen, but it degrades rapidly, reducing efficiency. To combat this tendency of ruthenium oxide to change oxidation states, it is combined with iridium, which has a tendency to stabilize ruthenium oxide at oxygen evolution potentials. The novel oxygen evolution catalyst was fabricated under flowing argon in order to allow the iridium to preferentially react with oxygen from the ruthenium oxide, and not oxygen from the environment. Nanoparticulate iridium black and anhydrous ruthenium oxide are weighed out and mixed to 5 18 atomic percent. They are then heat treated at 300 C under flowing argon (in order to create an inert environment) for a minimum of 14 hours. This temperature was chosen because it is approximately the creep temperature of ruthenium oxide, and is below the sintering temperature of both materials. In general, the temperature should always be below the sintering temperature of both materials. The iridium- doped ruthenium oxide catalyst is then fabricated into a PEM-based membrane- electrode assembly (MEA), and then mounted into test cells. The result is an electrolyzer system that can sustain electrolysis at twice the current density, and at the same efficiency as commercial catalysts in the range of 100-200 mA/sq cm. At 200 mA/sq cm, this new system operates at an efficiency of 85 percent, which is 2 percent greater than commercially available catalysts. Testing has shown that this material is as stable as commercially available oxygen evolution catalysts. This means that this new catalyst can be used to regenerate fuel cell systems in space, and as a hydrogen generator on Earth.

  19. [Forest soil seed bank and natural regeneration].

    Science.gov (United States)

    Yang, Y; Sun, X; Wang, P

    2001-04-01

    The characteristics of temporal dynamics and spatial distribution of forest soil seed bank and their effects on natural regeneration were reviewed in this paper. The density of the seed bank of forest soil, which is affected by the types and ages of forest, is lower than that of cultivated land and grassplot, and can vary widely. The extent to which the composition of forest soil seed bank is influenced by its counterpart plantation depends on the stages of succession. The dynamics of forest soil seed bank is the combined effect of periodical and random factors. It is suggested that forest soil seed bank is the material base of forest regeneration, and the configuration and function of forest soil seed bank would influence the ability and the direction of natural forest regeneration. According to the characteristics of forest soil seed bank and obstructive factors influencing regeneration, some artificial measures can be adopted to accelerate natural regeneration. Studies on the forest soil seed bank should focus on the application of basic theories of disturbed ecology, and regard the reconstruction of degenerative ecosystem and the succession of populations in the ecotone as the main contents to study. As for the research method, it is advisable to employ long-term and located observations.

  20. Thinning in artificially regenerated young beech stands

    Directory of Open Access Journals (Sweden)

    Novák Jiří

    2015-12-01

    Full Text Available Although beech stands are usually regenerated naturally, an area of up to 5,000 ha year−1 is artificially regenerated by beech in the Czech Republic annually. Unfortunately, these stands often showed insufficient stand density and, consequently, lower quality of stems. Therefore, thinning methods developed for naturally regenerated beech stands are applicable with difficulties. The paper evaluates the data from two thinning experiments established in young artificially regenerated beech stands located in different growing conditions. In both experiments, thinning resulted in the lower amount of salvage cut in following years. Positive effect of thinning on periodic stand basal area increment and on periodic diameter increment of dominant trees was found in the beech stand located at middle elevations. On the other hand, thinning effects in mountain conditions were negligible. Thinning focusing on future stand quality cannot be commonly applied in artificially regenerated beech stands because of their worse initial quality and lower density. However, these stands show good growth and response to thinning, hence their management can be focused on maximising beech wood production.

  1. Schumpeter's Evolution

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    This draft of a book on Schumpeter is distributed for commenting. It is a stylised intellectual biography that focus on the emergence and extension of the Schumpeterian vision and analysis of economic and social evolution. The draft provides novel interpretations of Schumpeter's six major books. He...... originally developed his evolutionary research programme in Wesen from 1908 by studying the inherent limitations of Neoclassical Economics. He presented core results on economic evolution and sketched an extension evolutionary analysis to all social sciences in Entwicklung from 1912. He made a partial...... reworking of his basic theory of economic evolution in Development from 1934, and this reworking was continued in Cycles from 1939. Here Schumpeter also tried to handle the statistical and historical evidence on the waveform evolution of the capitalist economy. Capitalism from 1942 modified the model...

  2. Common developmental pathways link tooth shape to regeneration

    Science.gov (United States)

    Fraser, Gareth J.; Bloomquist, Ryan F.; Streelman, J. Todd

    2013-01-01

    In many non-mammalian vertebrates, adult dentitions result from cyclical rounds of tooth regeneration wherein simple unicuspid teeth are replaced by more complex forms. Therefore and by contrast to mammalian models, the numerical majority of vertebrate teeth develop shape during the process of replacement. Here, we exploit the dental diversity of Lake Malawi cichlid fishes to ask how vertebrates generally replace their dentition and in turn how this process acts to influence resulting tooth morphologies. First, we used immunohistochemistry to chart organogenesis of continually replacing cichlid teeth and discovered an epithelial down-growth that initiates the replacement cycle via a labial proliferation bias. Next, we identified sets of co-expressed genes from common pathways active during de novo, lifelong tooth replacement and tooth morphogenesis. Of note, we found two distinct epithelial cell populations, expressing markers of dental competence and cell potency, which may be responsible for tooth regeneration. Related gene sets were simultaneously active in putative signaling centers associated with the differentiation of replacement teeth with complex shapes. Finally, we manipulated targeted pathways (BMP, FGF, Hh, Notch, Wnt/β-catenin) in vivo with small molecules and demonstrated dose-dependent effects on both tooth replacement and tooth shape. Our data suggest that the processes of tooth regeneration and tooth shape morphogenesis are integrated via a common set of molecular signals. This linkage has subsequently been lost or decoupled in mammalian dentitions where complex tooth shapes develop in first generation dentitions that lack the capacity for lifelong replacement. Our dissection of the molecular mechanics of vertebrate tooth replacement coupled to complex shape pinpoints aspects of odontogenesis that might be re-evolved in the lab to solve problems in regenerative dentistry. PMID:23422830

  3. A novel osteogenesis technique: The expansible guided bone regeneration

    Directory of Open Access Journals (Sweden)

    Osama Zakaria

    2012-12-01

    Full Text Available Guided bone regeneration is a unique osteogenesis technique that requires a barrier membrane under periosteum to create space for bone regeneration. However, creating sizeable spaces is clinically not commonly feasible. A titanium plate and a thin silicone membrane were surgically layered on each calvaria of eight rabbits. Then, the periphery of the silicone membrane was fixed by a plastic ring to the underlying bone using titanium micro screws. After 1 week, a 5-mm-length titanium screw was used to elevate the titanium plate, which in turn elevated the silicone membrane together with overlying soft tissue in a rate of 1 mm/day for 5 days to create a secluded space. Animals were killed at 2 months (n = 4, group 1 and 4 months (n = 4, group 2 after the elevation. Histological and microradiographical analyses demonstrated creation of an amount of de novo bone formation (68.2 ± 22 mm3 in group 1 and 70.3 ± 14 mm3 in group 2 in the sizeable created spaces (207.1 ± 31 mm3 in group 1 and 202 ± 21 mm3 in group 2 without exposure of the device. This novel osteogenesis technique, “expansible guided bone regeneration,” created a substantial in vivo incubator without applying growth factors or osteoprogenitor cells. Creating a growing space over the secluded surface allowed the development of normal biological healing process occurring on the bone surface into a regenerative process, generating bone outside the genetically determined skeletal bone. This technique is a new tissue engineering approach stimulating endogenous tissue repair without applying cells or factors exogenously.

  4. Common developmental pathways link tooth shape to regeneration.

    Science.gov (United States)

    Fraser, Gareth J; Bloomquist, Ryan F; Streelman, J Todd

    2013-05-15

    In many non-mammalian vertebrates, adult dentitions result from cyclical rounds of tooth regeneration wherein simple unicuspid teeth are replaced by more complex forms. Therefore and by contrast to mammalian models, the numerical majority of vertebrate teeth develop shape during the process of replacement. Here, we exploit the dental diversity of Lake Malawi cichlid fishes to ask how vertebrates generally replace their dentition and in turn how this process acts to influence resulting tooth morphologies. First, we used immunohistochemistry to chart organogenesis of continually replacing cichlid teeth and discovered an epithelial down-growth that initiates the replacement cycle via a labial proliferation bias. Next, we identified sets of co-expressed genes from common pathways active during de novo, lifelong tooth replacement and tooth morphogenesis. Of note, we found two distinct epithelial cell populations, expressing markers of dental competence and cell potency, which may be responsible for tooth regeneration. Related gene sets were simultaneously active in putative signaling centers associated with the differentiation of replacement teeth with complex shapes. Finally, we manipulated targeted pathways (BMP, FGF, Hh, Notch, Wnt/β-catenin) in vivo with small molecules and demonstrated dose-dependent effects on both tooth replacement and tooth shape. Our data suggest that the processes of tooth regeneration and tooth shape morphogenesis are integrated via a common set of molecular signals. This linkage has subsequently been lost or decoupled in mammalian dentitions where complex tooth shapes develop in first generation dentitions that lack the capacity for lifelong replacement. Our dissection of the molecular mechanics of vertebrate tooth replacement coupled to complex shape pinpoints aspects of odontogenesis that might be re-evolved in the lab to solve problems in regenerative dentistry. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. The process of urban regeneration in context of information society

    Directory of Open Access Journals (Sweden)

    Bazik Dragana

    2006-01-01

    Full Text Available This paper deals with the concept of innovation of the urban regeneration process in context of transformations which are generated by information-communication technologies. From one aspect, Serbia has an exceptional human potential presented in number of 13,000 graduates each year, or in share of 42% of population who speaks English, which is the largest among all Eastern and Central European countries. This forms a basis for formulation of strategies of information society development in Serbia as well as for economic adjustments based upon knowledge, and for tracing the way to future knowledge society, i.e. eEurope 2020. On the other hand, we are witnessing an intensive development of huge complexes of mega and hypermarkets as a present dominant way for our city spaces' regeneration. At the same time, experiences from some other locations point to the deterioration of cities' urban identity as a consequence of the global capital infiltration and of development within an urban tissue of a huge complex of multi-national companies. Aiming to overcome the mistakes portrayed by international experience, as well as potential oversights that may occur because of routine and mismatch between certain phases of the sustainable development process, this paper makes an emphasis on the importance of an integral evaluation of the information society development trends and the spatial aspects of urban regeneration. It is essential to adjust devastated urban spaces as artifacts of one technological era to the actual information era with indication of future digital knowledge era, i.e. to plan, design and develop *according to new technological requirements and possibilities for new working places and new quality of living.

  6. Nitrogen Chemistry and Coke Transformation of FCC Coked Catalyst during the Regeneration Process

    Science.gov (United States)

    Shi, Junjun; Guan, Jianyu; Guo, Dawei; Zhang, Jiushun; France, Liam John; Wang, Lefu; Li, Xuehui

    2016-06-01

    Regeneration of the coked catalyst is an important process of fluid catalytic cracking (FCC) in petroleum refining, however, this process will emit environmentally harmful gases such as nitrogen and carbon oxides. Transformation of N and C containing compounds in industrial FCC coke under thermal decomposition was investigated via TPD and TPO to examine the evolved gaseous species and TGA, NMR and XPS to analyse the residual coke fraction. Two distinct regions of gas evolution are observed during TPD for the first time, and they arise from decomposition of aliphatic carbons and aromatic carbons. Three types of N species, pyrrolic N, pyridinic N and quaternary N are identified in the FCC coke, the former one is unstable and tends to be decomposed into pyridinic and quaternary N. Mechanisms of NO, CO and CO2 evolution during TPD are proposed and lattice oxygen is suggested to be an important oxygen resource. Regeneration process indicates that coke-C tends to preferentially oxidise compared with coke-N. Hence, new technology for promoting nitrogen-containing compounds conversion will benefit the in-situ reduction of NO by CO during FCC regeneration.

  7. Morphology control of zinc regeneration for zinc-air fuel cell and battery

    Science.gov (United States)

    Wang, Keliang; Pei, Pucheng; Ma, Ze; Xu, Huachi; Li, Pengcheng; Wang, Xizhong

    2014-12-01

    Morphology control is crucial both for zinc-air batteries and for zinc-air fuel cells during zinc regeneration. Zinc dendrite should be avoided in zinc-air batteries and zinc pellets are yearned to be formed for zinc-air fuel cells. This paper is mainly to analyze the mechanism of shape change and to control the zinc morphology during charge. A numerical three-dimensional model for zinc regeneration is established with COMSOL software on the basis of ionic transport theory and electrode reaction electrochemistry, and some experiments of zinc regeneration are carried out. The deposition process is qualitatively analyzed by the kinetics Monte Carlo method to study the morphological change from the electrocrystallization point of view. Morphological evolution of deposited zinc under different conditions of direct currents and pulse currents is also investigated by simulation. The simulation shows that parametric variables of the flowing electrolyte, the surface roughness and the structure of the electrode, the charging current and mode affect morphological evolution. The uniform morphology of deposited zinc is attained at low current, pulsating current or hydrodynamic electrolyte, and granular morphology is obtained by means of an electrode of discrete columnar structure in combination with high current and flowing electrolyte.

  8. Evolution of Active Regions

    Directory of Open Access Journals (Sweden)

    Lidia van Driel-Gesztelyi

    2015-09-01

    Full Text Available The evolution of active regions (AR from their emergence through their long decay process is of fundamental importance in solar physics. Since large-scale flux is generated by the deep-seated dynamo, the observed characteristics of flux emergence and that of the subsequent decay provide vital clues as well as boundary conditions for dynamo models. Throughout their evolution, ARs are centres of magnetic activity, with the level and type of activity phenomena being dependent on the evolutionary stage of the AR. As new flux emerges into a pre-existing magnetic environment, its evolution leads to re-configuration of small-and large-scale magnetic connectivities. The decay process of ARs spreads the once-concentrated magnetic flux over an ever-increasing area. Though most of the flux disappears through small-scale cancellation processes, it is the remnant of large-scale AR fields that is able to reverse the polarity of the poles and build up new polar fields. In this Living Review the emphasis is put on what we have learned from observations, which is put in the context of modelling and simulation efforts when interpreting them. For another, modelling-focused Living Review on the sub-surface evolution and emergence of magnetic flux see Fan (2009. In this first version we focus on the evolution of dominantly bipolar ARs.

  9. Derepression of the plant Chromovirus LORE1 induces germline transposition in regenerated plants.

    Directory of Open Access Journals (Sweden)

    Eigo Fukai

    2010-03-01

    Full Text Available Transposable elements represent a large proportion of the eukaryotic genomes. Long Terminal Repeat (LTR retrotransposons are very abundant and constitute the predominant family of transposable elements in plants. Recent studies have identified chromoviruses to be a widely distributed lineage of Gypsy elements. These elements contain chromodomains in their integrases, which suggests a preference for insertion into heterochromatin. In turn, this preference might have contributed to the patterning of heterochromatin observed in host genomes. Despite their potential importance for our understanding of plant genome dynamics and evolution, the regulatory mechanisms governing the behavior of chromoviruses and their activities remain largely uncharacterized. Here, we report a detailed analysis of the spatio-temporal activity of a plant chromovirus in the endogenous host. We examined LORE1a, a member of the endogenous chromovirus LORE1 family from the model legume Lotus japonicus. We found that this chromovirus is stochastically de-repressed in plant populations regenerated from de-differentiated cells and that LORE1a transposes in the male germline. Bisulfite sequencing of the 5' LTR and its surrounding region suggests that tissue culture induces a loss of epigenetic silencing of LORE1a. Since LTR promoter activity is pollen specific, as shown by the analysis of transgenic plants containing an LTR::GUS fusion, we conclude that male germline-specific LORE1a transposition in pollen grains is controlled transcriptionally by its own cis-elements. New insertion sites of LORE1a copies were frequently found in genic regions and show no strong insertional preferences. These distinctive novel features of LORE1 indicate that this chromovirus has considerable potential for generating genetic and epigenetic diversity in the host plant population. Our results also define conditions for the use of LORE1a as a genetic tool.

  10. Regeneration of neural crest derivatives in the Xenopus tadpole tail

    Directory of Open Access Journals (Sweden)

    Slack Jonathan MW

    2007-05-01

    Full Text Available Abstract Background After amputation of the Xenopus tadpole tail, a functionally competent new tail is regenerated. It contains spinal cord, notochord and muscle, each of which has previously been shown to derive from the corresponding tissue in the stump. The regeneration of the neural crest derivatives has not previously been examined and is described in this paper. Results Labelling of the spinal cord by electroporation, or by orthotopic grafting of transgenic tissue expressing GFP, shows that no cells emigrate from the spinal cord in the course of regeneration. There is very limited regeneration of the spinal ganglia, but new neurons as well as fibre tracts do appear in the regenerated spinal cord and the regenerated tail also contains abundant peripheral innervation. The regenerated tail contains a normal density of melanophores. Cell labelling experiments show that melanophores do not arise from the spinal cord during regeneration, nor from the mesenchymal tissues of the skin, but they do arise by activation and proliferation of pre-existing melanophore precursors. If tails are prepared lacking melanophores, then the regenerates also lack them. Conclusion On regeneration there is no induction of a new neural crest similar to that seen in embryonic development. However there is some regeneration of neural crest derivatives. Abundant melanophores are regenerated from unpigmented precursors, and, although spinal ganglia are not regenerated, sufficient sensory systems are produced to enable essential functions to continue.

  11. Evolution of Autologous Chondrocyte Repair and Comparison to Other Cartilage Repair Techniques

    Directory of Open Access Journals (Sweden)

    Ashvin K. Dewan

    2014-01-01

    Full Text Available Articular cartilage defects have been addressed using microfracture, abrasion chondroplasty, or osteochondral grafting, but these strategies do not generate tissue that adequately recapitulates native cartilage. During the past 25 years, promising new strategies using assorted scaffolds and cell sources to induce chondrocyte expansion have emerged. We reviewed the evolution of autologous chondrocyte implantation and compared it to other cartilage repair techniques. Methods. We searched PubMed from 1949 to 2014 for the keywords “autologous chondrocyte implantation” (ACI and “cartilage repair” in clinical trials, meta-analyses, and review articles. We analyzed these articles, their bibliographies, our experience, and cartilage regeneration textbooks. Results. Microfracture, abrasion chondroplasty, osteochondral grafting, ACI, and autologous matrix-induced chondrogenesis are distinguishable by cell source (including chondrocytes and stem cells and associated scaffolds (natural or synthetic, hydrogels or membranes. ACI seems to be as good as, if not better than, microfracture for repairing large chondral defects in a young patient’s knee as evaluated by multiple clinical indices and the quality of regenerated tissue. Conclusion. Although there is not enough evidence to determine the best repair technique, ACI is the most established cell-based treatment for full-thickness chondral defects in young patients.

  12. Guided Bone Regeneration with Novel Bioabsorbable Membranes

    Science.gov (United States)

    Koyama, Yoshihisa; Kikuchi, Masanori; Yamada, Takeki; Kanaya, Tomohiro; Matsumoto, Hiroko N.; Takakuda, Kazuo; Miyairi, Hiroo; Tanaka, Junzo

    Guided Bone Regeneration (GBR) is a method for bone tissue regeneration. In this method, membranes are used to cover bone defects and to block the invasion of the surrounding soft tissues. It would provide sufficient time for the osteogenic cells from bone marrow to proliferate and form new bony tissues. In spite of the potential usefulness of this method, no appropriate materials for the GBR membrane have been developed. Here we design the ideal mechanical properties of the GBR membranes and created novel materials, which is the composite of β-tricalcium phosphate and block copolymer of L-lactide, glycolide and ɛ-caplolactone. In the animal experiments with the use of the trial products, we observed significant enhancement in the bone regeneration and proved the effectiveness of the materials.

  13. All-optical signal processing and regeneration

    DEFF Research Database (Denmark)

    Wolfson, David

    2001-01-01

    of a detailed large-signal model. An important parameter for SOA-based gates is the input power dynamic range (IPDR) as it determines the cascadability of the devices. Guidelines on how to maximise the IPDR are therefore established. Important trends are that short SOAs with low confinement factors and a low...... to conventional wavelength conversion since conversion of an optical clock signal is used instead of CW light. An investigation of these advantages is carried out and the feasibility of the scheme is demonstrated at 20 Gbit/s. A description of interferometric wavelength converters (IWCs) is also given. The high...... attractive for all-optical regeneration. Experiments carried out at 40 Gbit/s demonstrate excellent performance for 2R regeneration, which is emphasised by a clear improvement of the optical signal-to-noise ratio and a noise suppression capability. 3R regeneration is also illustrated at 40 Gbit/s, where...

  14. Planning and Implementation of Urban Regeneration

    DEFF Research Database (Denmark)

    Aunsborg, Christian; Sørensen, Michael Tophøj

    2008-01-01

    the regeneration challenge became an issue in the professional debate. The urban, economic and spatial problematics rising from structural development trends of society were subject to a committee work from 1999 through 2001. The work resulted in a number of recommendations comprising i.a. suggestions concerning...... new statutory tools to handle the spatial transformation of urban regeneration areas. The paper examines the subsequent development of Danish planning legislation with the purpose of determining whether the present 'statutory toolbox' can be considered sufficient compared to the problems...... and challenges emerging in practice. To evaluate the adequacy of the toolbox the paper draws on case studies on urban regeneration projects in three major Danish cities. The conclusion is that the legislative developments during the last five years must be considered very relevant to problem solving in practice...

  15. Fanning the flames to regenerate the heart.

    Science.gov (United States)

    Riley, Paul R

    2014-03-01

    Damage to the adult mammalian heart is irreversible, and lost cells are not replaced through regeneration. In neonatal mice, prior to P7, heart tissue can be regenerated after injury; however, the factors that facilitate cardiac regeneration in the neonatal heart are not known. In this issue of the JCI, Aurora and colleagues evaluated the immune response following myocardial infarction in P1 mice compared with that in P14 mice, which have lost their regenerative capacity, and identified a population of macrophages as mediators of cardiac repair. Further understanding of the immune modulators that promote the regenerative properties of this macrophage subset could potentially be exploited to recapitulate regenerative function in the adult heart.

  16. Covariant quantum Markovian evolutions

    Science.gov (United States)

    Holevo, A. S.

    1996-04-01

    Quantum Markovian master equations with generally unbounded generators, having physically relevant symmetries, such as Weyl, Galilean or boost covariance, are characterized. It is proven in particular that a fully Galilean covariant zero spin Markovian evolution reduces to the free motion perturbed by a covariant stochastic process with independent stationary increments in the classical phase space. A general form of the boost covariant Markovian master equation is discussed and a formal dilation to the Langevin equation driven by quantum Boson noises is described.

  17. Managing the new generation.

    Science.gov (United States)

    Dunn-Cane, K M; Gonzalez, J L; Stewart, H P

    1999-05-01

    As the Silent Generation quickly approaches retirement, and the Baby Boomer generation moves into management and supervisory roles, a new generation is entering the workforce. Generation Xers were born between 1965 and 1975, at a time when the country experienced high prices, wage inflation, stagnant consumer demands, and increased unemployment. Perhaps as a result, newcomers to today's workforce often have different characteristics, behavioral traits, and belief systems from their predecessors. To effectively supervise and motivate individuals from this unique generation, health care managers must begin by understanding the evolutions that have shaped each generation and influenced the workforce. In doing so, managers can create a thriving multigenerational work environment and embrace supervisory concepts that attract and motivate the new generation.

  18. Optimization for zeolite regeneration and nitrogen removal performance of a hypochlorite-chloride regenerant.

    Science.gov (United States)

    Zhang, Wei; Zhou, Zhen; An, Ying; Du, Silu; Ruan, Danian; Zhao, Chengyue; Ren, Ning; Tian, Xiaoce

    2017-07-01

    Simultaneous zeolites regeneration and nitrogen removal were investigated by using a mixed solution of NaClO and NaCl (NaClO-NaCl solution), and effects of the regenerant on ammonium removal performance and textural properties of zeolites were analyzed by long-term adsorption and regeneration operations. Mixed NaClO-NaCl solution removed more NH4+ exchanged on zeolites and converted more of them to nitrogen than using NaClO or NaCl solution alone. Response surface methodological analysis indicated that molar ratio of hypochlorite and nitrogen (ClO-/N), NaCl concentration and pH value all had significant effects on zeolites regeneration and NH4+ conversion to nitrogen, and the optimum condition was obtained at ClO-/N of 1.75, NaCl concentration of 20 g/L and pH of 10.0. Zeolites regenerated by mixed NaClO-NaCl solution showed higher ammonium adsorption rate and lower capacity than unused zeolites. Zeolites and the regeneration solution were both effective even after 20 cycles of use. Composition and morphological analysis revealed that the main mineral species and surface morphology of zeolites before and after NaClO-NaCl regeneration were unchanged. Textural analysis indicated that NaClO-NaCl regeneration leads to an increased surface area of zeolites, especially the microporosity. The results indicated that NaClO-NaCl regeneration is an attractive method to achieve sustainable removal of nitrogen from wastewater through zeolite. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Microscopic observations show invasion of inflammatory cells in the limb blastema and epidermis in pre-metamorphic frog tadpoles which destroy the Apical Epidermal CAP and impede regeneration.

    Science.gov (United States)

    Alibardi, Lorenzo

    2017-03-01

    Some limb regeneration in tadpoles of Rana dalmatina occurs at stages 44-48 when small hind-limbs are present while scarring occurs at stages 51-52 when forelimbs have developed and metamorphosis is approaching. Ultrastructural analysis of cells forming the regenerating blastema detects mesenchymal cells and an Apical Epidermal Cap (AEC) in regenerating limb blastema 5-6 days post-amputation at stages 46-48. In contrast, granulocytes and numerous macrophages and lymphocytes prevail over mesenchymal cells in limb blastema at stages 51-52, which are destined to form scars. An increase in inflammatory cells in limb blastema prior to metamorphosis suggests a negative influence of immune cells on limb regeneration. Inflammatory cells invade the apical wound epidermis where stem keratinocytes are likely destroyed, impeding the formation of an AEC, the microregion which leads to limb regeneration. The invasion of immune cells, however, may also represent a physiological consequence of the death of cell populations in the tadpoles occurring with approaching metamorphosis. The passage from an aquatic to a terrestrial life in this frog elicits the typical amniote scarring reaction after wounding, and the limb cannot regenerate. The present observations sustain the hypothesis that the evolution of the adaptive immunity in tetrapods while efficiently preserving adult self-condition, determined the loss of tissue regeneration since the embryonic antigens evocated in blastema cells are removed by immune cells of the adult. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. Hydride heat pump with heat regenerator

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  1. Adenovirus-mediated transfer of hepatocyte growth factor gene to human dental pulp stem cells under good manufacturing practice improves their potential for periodontal regeneration in swine.

    Science.gov (United States)

    Cao, Yu; Liu, Zhenhai; Xie, Yilin; Hu, Jingchao; Wang, Hua; Fan, Zhipeng; Zhang, Chunmei; Wang, Jingsong; Wu, Chu-Tse; Wang, Songlin

    2015-12-15

    Periodontitis is one of the most widespread infectious diseases in humans. We previously promoted significant periodontal tissue regeneration in swine models with the transplantation of autologous periodontal ligament stem cells (PDLSCs) and PDLSC sheet. We also promoted periodontal tissue regeneration in a rat model with a local injection of allogeneic bone marrow mesenchymal stem cells. The purpose of the present study is to investigate the roles of the hepatocyte growth factor (HGF) and human dental pulp stem cells (DPSCs) in periodontal tissue regeneration in swine. In the present study, we transferred an adenovirus that carried HGF gene into human DPSCs (HGF-hDPSCs) under good manufacturing practice (GMP) conditions. These cells were then transplanted into a swine model for periodontal regeneration. Twenty miniature pigs were used to generate periodontitis with bone defect of 5 mm in width, 7 mm in length, and 3 mm in depth. After 12 weeks, clinical, radiological, quantitative and histological assessment of regenerated periodontal tissues was performed to compare periodontal regeneration in swine treated with cell implantation. Our study showed that injecting HGF-hDPSCs into this large animal model could significantly improve periodontal bone regeneration and soft tissue healing. A hDPSC or HGF-hDPSC sheet showed superior periodontal tissue regeneration compared to the injection of dissociated cells. However, the sheets required surgical placement; thus, they were suitable for surgically-managed periodontitis treatments. The adenovirus-mediated transfer of the HGF gene markedly decreased hDPSC apoptosis in a hypoxic environment or in serum-free medium, and it increased blood vessel regeneration. This study indicated that HGF-hDPSCs produced under GMP conditions significantly improved periodontal bone regeneration in swine; thus, this method represents a potential clinical application for periodontal regeneration.

  2. Evolution and the origin of the visual retinoid cycle in vertebrates

    OpenAIRE

    Kusakabe, Takehiro G.; Takimoto, Noriko; Jin, Minghao; Tsuda, Motoyuki

    2009-01-01

    Absorption of a photon by visual pigments induces isomerization of 11-cis-retinaldehyde (RAL) chromophore to all-trans-RAL. Since the opsins lacking 11-cis-RAL lose light sensitivity, sustained vision requires continuous regeneration of 11-cis-RAL via the process called ‘visual cycle’. Protostomes and vertebrates use essentially different machinery of visual pigment regeneration, and the origin and early evolution of the vertebrate visual cycle is an unsolved mystery. Here we compare visual r...

  3. Whole Tooth Regeneration as a Future Dental Treatment.

    Science.gov (United States)

    Oshima, Masamitsu; Tsuji, Takashi

    2015-01-01

    Dental problems caused by dental caries, periodontal disease and tooth injury compromise the oral and general health issues. Current advances for the development of regenerative therapy have been influenced by our understanding of embryonic development, stem cell biology, and tissue engineering technology. Tooth regenerative therapy for tooth tissue repair and whole tooth replacement is currently expected a novel therapeutic concept with the full recovery of tooth physiological functions. Dental stem cells and cell-activating cytokines are thought to be candidate approach for tooth tissue regeneration because they have the potential to differentiate into tooth tissues in vitro and in vivo. Whole tooth replacement therapy is considered to be an attractive concept for next generation regenerative therapy as a form of bioengineered organ replacement. For realization of whole tooth regeneration, we have developed a novel three-dimensional cell manipulation method designated the "organ germ method". This method involves compartmentalisation of epithelial and mesenchymal cells at a high cell density to mimic multicellular assembly conditions and epithelial-mesenchymal interactions in organogenesis. The bioengineered tooth germ generates a structurally correct tooth in vitro, and erupted successfully with correct tooth structure when transplanted into the oral cavity. We have ectopically generated a bioengineered tooth unit composed of a mature tooth, periodontal ligament and alveolar bone, and that tooth unit was engrafted into an adult jawbone through bone integration. Bioengineered teeth were also able to perform physiological tooth functions such as mastication, periodontal ligament function and response to noxious stimuli. In this review, we describe recent findings and technologies underpinning whole tooth regenerative therapy.

  4. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water

    Science.gov (United States)

    The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to ...

  5. Regeneration of hair cells in the mammalian vestibular system.

    Science.gov (United States)

    Li, Wenyan; You, Dan; Chen, Yan; Chai, Renjie; Li, Huawei

    2016-06-01

    Hair cells regenerate throughout the lifetime of non-mammalian vertebrates, allowing these animals to recover from hearing and balance deficits. Such regeneration does not occur efficiently in humans and other mammals. Thus, balance deficits become permanent and is a common sensory disorder all over the world. Since Forge and Warchol discovered the limited spontaneous regeneration of vestibular hair cells after gentamicininduced damage in mature mammals, significant efforts have been exerted to trace the origin of the limited vestibular regeneration in mammals after hair cell loss. Moreover, recently many strategies have been developed to promote the hair cell regeneration and subsequent functional recovery of the vestibular system, including manipulating the Wnt, Notch and Atoh1. This article provides an overview of the recent advances in hair cell regeneration in mammalian vestibular epithelia. Furthermore, this review highlights the current limitations of hair cell regeneration and provides the possible solutions to regenerate functional hair cells and to partially restore vestibular function.

  6. In vitro regeneration of sweet potato (Ipomoea batatas (L.) Lam ...

    African Journals Online (AJOL)

    Ipomoea batatas (L.) Lam.) yield. The establishment of in vitro regeneration protocol for this plant is essential to improve it through tissue culture and genetic engineering. The objective of this study was to establish in vitro regeneration protocol ...

  7. Evolutionary Loss of Animal Regeneration: Pattern and Process

    National Research Council Canada - National Science Library

    Alexandra E. Bely

    2010-01-01

    ... animals, describe some of the clearest examples of regeneration loss, discuss some possible scenarios by which regeneration may be lost, and review recent work in annelids that is providing new insights into loss of regenerative ability.

  8. Macrophages are necessary for epimorphic regeneration in African spiny mice

    Science.gov (United States)

    Simkin, Jennifer; Gawriluk, Thomas R; Gensel, John C; Seifert, Ashley W

    2017-01-01

    How the immune system affects tissue regeneration is not well understood. In this study, we used an emerging mammalian model of epimorphic regeneration, the African spiny mouse, to examine cell-based inflammation and tested the hypothesis that macrophages are necessary for regeneration. By directly comparing inflammatory cell activation in a 4 mm ear injury during regeneration (Acomys cahirinus) and scarring (Mus musculus), we found that both species exhibited an acute inflammatory response, with scarring characterized by stronger myeloperoxidase activity. In contrast, ROS production was stronger and more persistent during regeneration. By depleting macrophages during injury, we demonstrate a functional requirement for these cells to stimulate regeneration. Importantly, the spatial distribution of activated macrophage subtypes was unique during regeneration with pro-inflammatory macrophages failing to infiltrate the regeneration blastema. Together, our results demonstrate an essential role for inflammatory cells to regulate a regenerative response. DOI: http://dx.doi.org/10.7554/eLife.24623.001 PMID:28508748

  9. Proteinuria Impairs Podocyte Regeneration by Sequestering Retinoic Acid

    Science.gov (United States)

    Peired, Anna; Angelotti, Maria Lucia; Ronconi, Elisa; la Marca, Giancarlo; Mazzinghi, Benedetta; Sisti, Alessandro; Lombardi, Duccio; Giocaliere, Elisa; Della Bona, Marialuisa; Villanelli, Fabio; Parente, Eliana; Ballerini, Lara; Sagrinati, Costanza; Wanner, Nicola; Huber, Tobias B.; Liapis, Helen; Lazzeri, Elena; Lasagni, Laura

    2013-01-01

    In CKD, the risk of kidney failure and death depends on the severity of proteinuria, which correlates with the extent of podocyte loss and glomerular scarring. We investigated whether proteinuria contributes directly to progressive glomerulosclerosis through the suppression of podocyte regeneration and found that individual components of proteinuria exert distinct effects on renal progenitor survival and differentiation toward a podocyte lineage. In particular, albumin prevented podocyte differentiation from human renal progenitors in vitro by sequestering retinoic acid, thus impairing retinoic acid response element (RARE)-mediated transcription of podocyte-specific genes. In mice with Adriamycin nephropathy, a model of human FSGS, blocking endogenous retinoic acid synthesis increased proteinuria and exacerbated glomerulosclerosis. This effect was related to a reduction in podocyte number, as validated through genetic podocyte labeling in NPHS2.Cre;mT/mG transgenic mice. In RARE-lacZ transgenic mice, albuminuria reduced retinoic acid bioavailability and impaired RARE activation in renal progenitors, inhibiting their differentiation into podocytes. Treatment with retinoic acid restored RARE activity and induced the expression of podocyte markers in renal progenitors, decreasing proteinuria and increasing podocyte number, as demonstrated in serial biopsy specimens. These results suggest that albumin loss through the damaged filtration barrier impairs podocyte regeneration by sequestering retinoic acid and promotes the generation of FSGS lesions. Our findings may explain why reducing proteinuria delays CKD progression and provide a biologic rationale for the clinical use of pharmacologic modulators to induce regression of glomerular diseases. PMID:23949798

  10. Graphene oxide as a scaffold for bone regeneration.

    Science.gov (United States)

    Holt, Brian D; Wright, Zoe M; Arnold, Anne M; Sydlik, Stefanie A

    2017-05-01

    Graphene oxide (GO), the oxidized form of graphene, holds great potential as a component of biomedical devices, deriving utility from its ability to support a broad range of chemical functionalities and its exceptional mechanical, electronic, and thermal properties. GO composites can be tuned chemically to be biomimetic, and mechanically to be stiff yet strong. These unique properties make GO-based materials promising candidates as a scaffold for bone regeneration. However, questions still exist as to the compatibility and long-term toxicity of nanocarbon materials. Unlike other nanocarbons, GO is meta-stable, water dispersible, and autodegrades in water on the timescale of months to humic acid-like materials, the degradation products of all organic matter. Thus, GO offers better prospects for biological compatibility over other nanocarbons. Recently, many publications have demonstrated enhanced osteogenic performance of GO-containing composites. Ongoing work toward surface modification or coating strategies could be useful to minimize the inflammatory response and improve compatibility of GO as a component of medical devices. Furthermore, biomimetic modifications could offer mechanical and chemical environments that encourage osteogenesis. So long as care is given to assure their safety, GO-based materials may be poised to become the next generation scaffold for bone regeneration. WIREs Nanomed Nanobiotechnol 2017, 9:e1437. doi: 10.1002/wnan.1437 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

  11. Urban Voids: renewal and regeneration experiences in Naples

    Directory of Open Access Journals (Sweden)

    Gabriella Punziano

    2017-12-01

    Full Text Available City and society, by definition unstable, constantly redefine the relation between places and actors, generating frequently critical circumstances that are addressed by only temporary solutions. The unexpected and uncontrolled social conditions and lifestyles build new geographies and centres. The activities of dismantlement, degradation, reuse, abandonment, and land use, continuously blend materials and relationships and requires rethinking the methods of describing the city and defining a new grammar of representation closer to the contemporary space, materials, actors, and relationship. Focusing on experiences of renewal, regeneration and recycle, the objective of this exploratory study is to investigate their different impacts in a well-known complex urban system as Naples. The study emphases on the urban and social dimensions, favouring a descriptive and visual perspective from those who experience life in the city, considering  the processes implemented by local actors and the reactions of inhabitants to these processes. Infact in Naples, despite its critical conditions, it is possible to trace signals indicating small informal practices of re-use in vacant or ruined areas, as well as existing small-scale clustering processes to re-adapt single buildings or spaces for new uses. So,  this study uses an innovative methodology to investigate this emerging implied writing as a set of latent questions and needs expressing renewal, regeneration and recycle phenomena. Through this technique, we will focus on the images of the city and its development trajectories.

  12. Burhanpur Cultural Landscape Conservation: Inspiring Quality for Sustainable Regeneration

    Directory of Open Access Journals (Sweden)

    Amit Wahurwagh

    2015-01-01

    Full Text Available The heritage landscape of Burhanpur has an architectural and horticultural composition, consisting of many historic gardens, a unique water management system, a sustainable planning and design framework, the use of landscape and topography with numerous heritage components and historical monuments, temples, tombs and mosques that are locally, regionally and nationally significant. Conserving Burhanpur as an inspirational model for other sites is not only a cultural heritage objective, but it is also a crucial component of the heritage-based sustainable regeneration of the landscape, because it is directly linked to environmental integrity, economic efficiency and resources for present and future generations. Although the last decade has witnessed vigorous efforts by the municipal corporation to preserve and develop Burhanpur by designating it as one of the heritage cities of the UNESCO—Indian Heritage Cities Network (in 2006, a coherent, holistic and sustainable heritage outcome has not been achieved. This paper proposes to harness the cultural landscape as an approach for the sustainable regeneration of Burhanpur heritage and takes a holistic approach to the interpretation of the historic district and natural landscape of the city, where historic buildings are located.

  13. Integrating Biomaterials and Stem Cells for Neural Regeneration.

    Science.gov (United States)

    Maclean, Francesca L; Rodriguez, Alexandra L; Parish, Clare L; Williams, Richard J; Nisbet, David R

    2016-02-01

    The central nervous system has a limited capacity to regenerate, and thus, traumatic injuries or diseases often have devastating consequences. Therefore, there is a distinct need to develop alternative treatments that can achieve functional recovery without side effects currently observed with some pharmacological treatments. Combining biomaterials with pluripotent stem cells (PSCs), either embryonic or induced, has the potential to revolutionize the treatment of neurodegenerative diseases and traumatic injuries. Biomaterials can mimic the extracellular matrix and present a myriad of relevant biochemical cues through rational design or further functionalization. Biomaterials such as nanofibers and hydrogels, including self-assembling peptide (SAP) hydrogels can provide a superior cell culture environment. When these materials are then combined with PSCs, more accurate drug screening and disease modeling could be developed, and the generation of large number of cells with the appropriate phenotype can be achieved, for subsequent use in vitro. Biomaterials have also been shown to support endogenous cell growth after implantation, and, in particular, hydrogels and SAPs have effectively acted as cell delivery vehicles, increasing cell survival after transplantation. Few studies are yet to fully exploit the combination of PSCs and innovative biomaterials; however, initial studies with neural stem cells, for example, are promising, and, hence, such a combination for use in vitro and in vivo is an exciting new direction for the field of neural regeneration.

  14. Neoblast Specialization in Regeneration of the Planarian Schmidtea mediterranea

    Directory of Open Access Journals (Sweden)

    M. Lucila Scimone

    2014-08-01

    Full Text Available Planarians can regenerate any missing body part in a process requiring dividing cells called neoblasts. Historically, neoblasts have largely been considered a homogeneous stem cell population. Most studies, however, analyzed neoblasts at the population rather than the single-cell level, leaving the degree of heterogeneity in this population unresolved. We combined RNA sequencing of neoblasts from wounded planarians with expression screening and identified 33 transcription factors transcribed in specific differentiated cells and in small fractions of neoblasts during regeneration. Many neoblast subsets expressing distinct tissue-associated transcription factors were present, suggesting candidate specification into many lineages. Consistent with this possibility, klf, pax3/7, and FoxA were required for the differentiation of cintillo-expressing sensory neurons, dopamine-β-hydroxylase-expressing neurons, and the pharynx, respectively. Together, these results suggest that specification of cell fate for most-to-all regenerative lineages occurs within neoblasts, with regenerative cells of blastemas being generated from a highly heterogeneous collection of lineage-specified neoblasts.

  15. Neoblast specialization in regeneration of the planarian Schmidtea mediterranea.

    Science.gov (United States)

    Scimone, M Lucila; Kravarik, Kellie M; Lapan, Sylvain W; Reddien, Peter W

    2014-08-12

    Planarians can regenerate any missing body part in a process requiring dividing cells called neoblasts. Historically, neoblasts have largely been considered a homogeneous stem cell population. Most studies, however, analyzed neoblasts at the population rather than the single-cell level, leaving the degree of heterogeneity in this population unresolved. We combined RNA sequencing of neoblasts from wounded planarians with expression screening and identified 33 transcription factors transcribed in specific differentiated cells and in small fractions of neoblasts during regeneration. Many neoblast subsets expressing distinct tissue-associated transcription factors were present, suggesting candidate specification into many lineages. Consistent with this possibility, klf, pax3/7, and FoxA were required for the differentiation of cintillo-expressing sensory neurons, dopamine-β-hydroxylase-expressing neurons, and the pharynx, respectively. Together, these results suggest that specification of cell fate for most-to-all regenerative lineages occurs within neoblasts, with regenerative cells of blastemas being generated from a highly heterogeneous collection of lineage-specified neoblasts. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Hamstring Tendon Regeneration After Harvesting: A Systematic Review.

    Science.gov (United States)

    Suijkerbuijk, Mathijs A M; Reijman, Max; Lodewijks, Susanne J M; Punt, Jorien; Meuffels, Duncan E

    2015-10-01

    Hamstring tendons are often used as autografts for anterior cruciate ligament (ACL) reconstruction. However, no systematic review has been performed describing consequences such as hamstring tendon regeneration rate and determinants of hamstring tendon regeneration. To summarize the current literature regarding hamstring tendon rate regeneration, the time course of regeneration, and determinants of hamstring regeneration. Systematic review. A search was performed in the Embase, Medline (OvidSP), Web of Science, Cochrane, PubMed, and Google Scholar databases up to June 2014 to identify relevant articles. A study was eligible if it met the following inclusion criteria: tendons were harvested, regeneration at harvest site was assessed, population size was at least 10 human subjects, full-text article was available, and the study design was either a randomized controlled trial, prospective cohort study, retrospective cohort study, or case control study. A risk of bias assessment of the eligible articles was determined. Data describing hamstring tendon regeneration rates were pooled per time period. A total of 18 publications met the inclusion criteria. The mean regeneration rate for the semitendinosus and gracilis tendons was, in all cases, 70% or higher. More than 1 year after harvesting, 79% (median [IQR], 80 [75.5-90]) of the semitendinosus tendons and 72% (median [IQR], 80 [61-88.5]) of the gracilis tendons were regenerated. No significant differences in regeneration rate could be found considering patient sex, age, height, weight, or duration of immobilization. Results did not clearly show whether absence of regeneration disadvantages the subsequent hamstring function. Five studies measured the regeneration rate at different moments in time. Hamstring tendons regenerated in the majority of patients after ACL reconstruction. The majority of the hamstring tendon regeneration was found to occur between 1 month and 1 year after harvest. No significant determinants for

  17. Germ cell regeneration-mediated, enhanced mutagenesis in the ascidian Ciona intestinalis reveals flexible germ cell formation from different somatic cells.

    Science.gov (United States)

    Yoshida, Keita; Hozumi, Akiko; Treen, Nicholas; Sakuma, Tetsushi; Yamamoto, Takashi; Shirae-Kurabayashi, Maki; Sasakura, Yasunori

    2017-03-15

    The ascidian Ciona intestinalis has a high regeneration capacity that enables the regeneration of artificially removed primordial germ cells (PGCs) from somatic cells. We utilized PGC regeneration to establish efficient methods of germ line mutagenesis with transcription activator-like effector nucleases (TALENs). When PGCs were artificially removed from animals in which a TALEN pair was expressed, somatic cells harboring mutations in the target gene were converted into germ cells, this germ cell population exhibited higher mutation rates than animals not subjected to PGC removal. PGC regeneration enables us to use TALEN expression vectors of specific somatic tissues for germ cell mutagenesis. Unexpectedly, cis elements for epidermis, neural tissue and muscle could be used for germ cell mutagenesis, indicating there are multiple sources of regenerated PGCs, suggesting a flexibility of differentiated Ciona somatic cells to regain totipotency. Sperm and eggs of a single hermaphroditic, PGC regenerated animal typically have different mutations, suggesting they arise from different cells. PGCs can be generated from somatic cells even though the maternal PGCs are not removed, suggesting that the PGC regeneration is not solely an artificial event but could have an endogenous function in Ciona. This study provides a technical innovation in the genome-editing methods, including easy establishment of mutant lines. Moreover, this study suggests cellular mechanisms and the potential evolutionary significance of PGC regeneration in Ciona. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Neurotrophic Keratopathy: Therapeutic Approach Using a Novel Matrix Regenerating Agent.

    Science.gov (United States)

    Guerra, Marta; Marques, Sara; Gil, João Quadrado; Campos, Joana; Ramos, Paula; Rosa, Andreia Martins; Quadrado, Maria João; Murta, Joaquim Neto

    2017-11-01

    To evaluate the efficacy and tolerance of a new matrix-regenerating agent (RGTA), Cacicol ® , a polymer that mimics heparan sulfates bound to extracellular matrix proteins, avoiding its proteolysis, to treat neurotrophic keratopathy (NK). Uncontrolled prospective clinical study performed between January 2014 and May 2016. Twenty-five patients (25 eyes) with corneal neurotrophic ulcers, nonresponsive to at least 2 weeks of conservative therapy, were treated with Cacicol, instilled once/twice a week. During follow-up, slit-lamp examination, anterior segment photography, fluorescein-dye testing, and best-corrected visual acuity were analyzed. Ulcer evolution was evaluated using image analysis software (ImageJ ® ) and healing defined as decrease of the corneal ulcer area. An independent observer measured ulcer area. All patients had complete corneal healing within an average of 4.13 ± 2.32 weeks. Mean ulcer area decreased significantly (P = 0.001) from 16.51% ± 18.56% (1st day) to 8.68% ± 11.25% at the 7th day and to 4.73% ± 10.75% at the 14th day. Compared with day 1, mean ulcer area decreased 60.24% after 7 days (P = 0.001), 54.92% after 14 days (P = 0.059), and 83.00% after 21 days (P = 0.003). Two cases of recurrence (8.0%) were registered. No systemic or local side effects were noticed. The new regenerating agent, Cacicol, represents an effective and safe therapy to treat NK.

  19. Regulation of Injury-Induced Ovarian Regeneration by Activation of Oogonial Stem Cells.

    Science.gov (United States)

    Erler, Piril; Sweeney, Alexandra; Monaghan, James R

    2017-01-01

    Some animals have the ability to generate large numbers of oocytes throughout life. This raises the question whether persistent adult germline stem cell populations drive continuous oogenesis and whether they are capable of mounting a regenerative response after injury. Here we demonstrate the presence of adult oogonial stem cells (OSCs) in the adult axolotl salamander ovary and show that ovarian injury induces OSC activation and functional regeneration of the ovaries to reproductive capability. Cells that have morphological similarities to germ cells were identified in the developing and adult ovaries via histological analysis. Genes involved in germ cell maintenance including Vasa, Oct4, Sox2, Nanog, Bmp15, Piwil1, Piwil2, Dazl, and Lhx8 were expressed in the presumptive OSCs. Colocalization of Vasa protein with H3 mitotic marker showed that both oogonial and spermatogonial adult stem cells were mitotically active. Providing evidence of stemness and viability of adult OSCs, enhanced green fluorescent protein (EGFP) adult OSCs grafted into white juvenile host gonads gave rise to EGFP OSCs, and oocytes. Last, the axolotl ovaries completely regenerated after partial ovariectomy injury. During regeneration, OSC activation resulted in rapid differentiation into new oocytes, which was demonstrated by Vasa+ /BrdU+ coexpression. Furthermore, follicle cell proliferation promoted follicle maturation during ovarian regeneration. Overall, these results show that adult oogenesis occurs via proliferation of endogenous OSCs in a tetrapod and mediates ovarian regeneration. This study lays the foundations to elucidate mechanisms of ovarian regeneration that will assist regenerative medicine in treating premature ovarian failure and reduced fertility. Stem Cells 2017;35:236-247. © 2016 AlphaMed Press.

  20. Gene expression patterns specific to the regenerating limb of the Mexican axolotl

    Directory of Open Access Journals (Sweden)

    James R. Monaghan

    2012-07-01

    Salamander limb regeneration is dependent upon tissue interactions that are local to the amputation site. Communication among limb epidermis, peripheral nerves, and mesenchyme coordinate cell migration, cell proliferation, and tissue patterning to generate a blastema, which will form missing limb structures. An outstanding question is how cross-talk between these tissues gives rise to the regeneration blastema. To identify genes associated with epidermis-nerve-mesenchymal interactions during limb regeneration, we examined histological and transcriptional changes during the first week following injury in the wound epidermis and subjacent cells between three injury types; 1 a flank wound on the side of the animal that will not regenerate a limb, 2 a denervated limb that will not regenerate a limb, and 3 an innervated limb that will regenerate a limb. Early, histological and transcriptional changes were similar between the injury types, presumably because a common wound-healing program is employed across anatomical locations. However, some transcripts were enriched in limbs compared to the flank and are associated with vertebrate limb development. Many of these genes were activated before blastema outgrowth and expressed in specific tissue types including the epidermis, peripheral nerve, and mesenchyme. We also identified a relatively small group of transcripts that were more highly expressed in innervated limbs versus denervated limbs. These transcripts encode for proteins involved in myelination of peripheral nerves, epidermal cell function, and proliferation of mesenchymal cells. Overall, our study identifies limb-specific and nerve-dependent genes that are upstream of regenerative growth, and thus promising candidates for the regulation of blastema formation.

  1. Adventitious shoot regeneration from in vitro stem explants of ...

    African Journals Online (AJOL)

    An efficient in vitro plant regeneration system from stem explants was established in Phellodendron amurense. Factors influencing shoot regeneration from stems including culture medium type, combinations of plant growth regulators and carbon source in the medium were investigated. Adventitious shoot regeneration was ...

  2. Development of an efficient plant regeneration protocol for sweet ...

    African Journals Online (AJOL)

    An efficient and reproducible plant regeneration protocol for the South African sweet potato (Ipomoea batatas Lam.) cultivar Blesbok was developed in this study. The effect of different hormone combinations and type of explant on shoot regeneration was evaluated in order to optimize the regeneration protocol. Explants in ...

  3. Laboratory studies on vegetative regeneration of the gametophyte of ...

    African Journals Online (AJOL)

    Microscope observation revealed that the protoplast used for regeneration was only part of the protoplasm and the regeneration process was complete in 12 h. The survival rate of ... A relatively completed life history of B. hypnoides is established with newly discovered propagation methods, namely protoplast regeneration.

  4. Natural regeneration - small ownerships from concept to practice

    Science.gov (United States)

    Arthur G., Jr. Dodge

    1977-01-01

    Established concepts of successful natural regeneration are not necessarily practiced on small ownerships of ten to 500 acres. Unevenage management will be the primary management system on small ownerships and natural regeneration is the most practical method of providing for continuous forest production. We can obtain satisfactory natural regeneration by good planning...

  5. High-efficiency regeneration of peanut ( Arachis hypogaea L.) plants ...

    African Journals Online (AJOL)

    A high-efficiency regeneration system for peanut plants was established. The regeneration frequency of leaf discs reached 40.9% on Murashige and Skoog medium supplemented with 0.5 mg l-1 naphthylacetic acid and 0.5 mg l-1 thidiazuron. The regenerated shoots elongated, developed roots and produced seeds.

  6. Establishment of plant regeneration system from anther culture of ...

    African Journals Online (AJOL)

    Frequencies of callus induction and shoot regeneration were 100 and 70.5%, respectively with the whole regeneration procedure completed in 40 days under light. This highly efficient, rapid regeneration system can be applied for both genetic transformation and doubled haploid plant induction. Key words: Tagetes patula, ...

  7. Evaluation of lymphatic regeneration in rat incisional wound healing ...

    African Journals Online (AJOL)

    Objective: During the wound healing process, lymphatic regeneration in the injured skin has not been fully investigated. This work was designed to study the regeneration of lymphatic vessels in rat incisional wounds in relation to the duration after the wound infliction. Material and methods: We studied the regeneration of ...

  8. The Role of Pannexin Hemichannels in Inflammation and Regeneration

    OpenAIRE

    Makarenkova, Helen P.; Shestopalov, Valery I.

    2014-01-01

    Tissue injury involves coordinated systemic responses including inflammatory response, targeted cell migration, cell-cell communication, stem cell activation and proliferation, and tissue regeneration. The inflammatory response is an important prerequisite for regeneration. Multiple studies suggest that extensive cell-cell communication during tissue regeneration is coordinated by purinergic signaling via extracellular ATP. Most recent data indicates that ATP release for such communication is...

  9. Regeneration potential of seedling explants of chilli ( Capsicum ...

    African Journals Online (AJOL)

    A study was conducted with hypocotyl, cotyledon and shoot tip of chilli as explants for regeneration on MS medium supplemented with different concentrations and combinations of auxins and cytokinins. Regeneration potential was determined by two ways. One is regeneration of shoot via callus formation from hypocotyls ...

  10. Effect of the characters of chitosans used and regeneration conditions on the yield and physicochemical characteristics of regenerated products

    National Research Council Canada - National Science Library

    Hsu, Chu Hsi; Chen, Szu Kai; Chen, Wei Yu; Tsai, Min Lang; Chen, Rong Huei

    2015-01-01

    The objective of this study was to explore the effect of the character of chitosans used, and the regeneration conditions employed on, the yield and physicochemical characteristics of regenerated products...

  11. Bone Adaptation and Regeneration - New Developments

    Science.gov (United States)

    Klein-Nulend, Jenneke; Bacabac, Rommel Gaud

    osteocytes sensing different canalicular flow patterns around cutting cone and reversal zone during loading, thus determining the bone's structure. Disturbances in architecture and permeability of the 3D porous network will affect transduction of mechanical loads to the mechanosensors. Uncovering the cellular and mechanical basis of the osteocyte's response to loading represents a significant challenge to our understanding of cellular mechanotransduction and bone remodeling. In view of the importance of mechanical stress for maintaining bone strength, mechanical stimuli have great potential for providing a therapeutic approach for bone (re)generation.

  12. Animal evolution

    DEFF Research Database (Denmark)

    Nielsen, Claus

    This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes it possi......This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes...

  13. Reintegration of the regenerated and the remaining tissues during joint regeneration in the newt Cynops pyrrhogaster

    National Research Council Canada - National Science Library

    Tsutsumi, Rio; Inoue, Takeshi; Yamada, Shigehito; Agata, Kiyokazu

    2015-01-01

    ... (matched in size and shape). Here we used newt joint regeneration as a model to investigate reintegration, because a functionally interlocking joint requires structural integration between its opposing skeletal elements...

  14. Modeling of active magnetic regenerators and experimental investigation of passive regenerators with oscillating flow

    DEFF Research Database (Denmark)

    Lei, Tian

    This thesis presents numerical modeling of active magnetic regenerator (AMR) and passive regenerator tests with oscillating flow. The work serves to investigate and improve the understanding of emerging concepts and technologies in the area of magnetic refrigeration. The discretization scheme...... of a one dimensional (1D) AMR model is improved for decreasing spurious temperature oscillations in the numerical solution. This transient AMR model is further modified for simulating tapered regenerators, heat loss through the housing wall and regenerators using mixed materials. Magnetocaloric materials...... and deduced indicators, including the pressure drop, friction factor, effectiveness, heating power and overall Nusselt number. Finally, based on the research in this thesis, the perspectives and some suggestions for the future work are given....

  15. Nanorheology of regenerated silk fibroin solution

    Indian Academy of Sciences (India)

    We have investigated the rheological properties of regenerated silk fibroin (RSF), a viscoelastic material at micro and nano length scales, by video microscopy. We describe here the principles and technique of video microscopy as a tool in such investigations. In this work, polystyrene beads were dispersed in the matrix of ...

  16. Nucellar embryogenesis and plantlet regeneration in ...

    African Journals Online (AJOL)

    Gamborg's B5 macronutrients, Murashige and Skoog micronutrients, iron source, vitamins and organics were used as standard basal media for all types of media used at each stage of somatic embryo development and regeneration. Induction medium 2 containing 2 mg/l 2,4-Dichlorophenoxyacetic acid and 0.5 mg/l ...

  17. Direct shoot organogenesis and plant regeneration from ...

    African Journals Online (AJOL)

    Using the whole cotyledonary node as explants, a rapid and efficient regeneration protocol was established for kenaf (Hibiscus cannabinus L.) on Murashige and Skoog (MS) basal medium. The effects of the plant growth regulators: N6-benzyladenine (BA), indole-3-aceticacid (IAA) and the non-ironic surfactant pluronic ...

  18. Bioinorganics: synthetic growth factors for bone regeneration

    NARCIS (Netherlands)

    Tahmasebi Birgani, Zeinab

    2016-01-01

    Bone tissue is naturally able to regenerate when damaged. However, in many large defects caused by fractures due to aging or osteoporosis, trauma, tumor removal, etc., the natural regenerative ability of bone is not sufficient to fully heal the defect. In such cases, a graft is required to support

  19. Anatomy, biogenesis and regeneration of salivary glands.

    Science.gov (United States)

    Holmberg, Kyle V; Hoffman, Matthew P

    2014-01-01

    An overview of the anatomy and biogenesis of salivary glands is important in order to understand the physiology, functions and disorders associated with saliva. A major disorder of salivary glands is salivary hypofunction and resulting xerostomia, or dry mouth, which affects hundreds of thousands of patients each year who suffer from salivary gland diseases or undergo head and neck cancer treatment. There is currently no curative therapy for these patients. To improve these patients' quality of life, new therapies are being developed based on findings in salivary gland cell and developmental biology. Here we discuss the anatomy and biogenesis of the major human salivary glands and the rodent submandibular gland, which has been used extensively as a research model. We also include a review of recent research on the identification and function of stem cells in salivary glands, and the emerging field of research suggesting that nerves play an instructive role during development and may be essential for adult gland repair and regeneration. Understanding the molecular mechanisms involved in gland biogenesis provides a template for regenerating, repairing or reengineering diseased or damaged adult human salivary glands. We provide an overview of 3 general approaches currently being developed to regenerate damaged salivary tissue, including gene therapy, stem cell-based therapy and tissue engineering. In the future, it may be that a combination of all three will be used to repair, regenerate and reengineer functional salivary glands in patients to increase the secretion of their saliva, the focus of this monograph.

  20. Optimization of regeneration and transformation parameters in ...

    African Journals Online (AJOL)

    PRECIOUS

    effects on the final product quality (Park et al., 2005;. Zhang and Blumwald, 2001; Jia et al., 2002; Lee et al.,. 2003). The establishment of an efficient in vitro regeneration and transformation protocol is a prerequisite for the genetic improvement of tomato. Although. Agrobacterium-mediated tomato transformation was.

  1. Direct shoot organogenesis and plant regeneration from ...

    African Journals Online (AJOL)

    Jane

    2010-12-13

    Dec 13, 2010 ... Kenaf cultivar P3B was conserved in the Laboratory of Bastfibre. Crops of Guangxi University. Seeds were ..... Planta,. 47: 585-588. Srivatanakul M, Park SH, Sanders JR, Salas MG, Smith RH (2000). Multiple shoot regeneration of kenaf (Hibiscus cannabinus L.) from a shoot apex culture system. Plant Cell ...

  2. Plant Regeneration and Genetic Transformation in Eggplant ...

    African Journals Online (AJOL)

    Dr Harmander Gill

    2014-02-05

    Feb 5, 2014 ... http://www.academicjournals.org/AJB. African Journal of Biotechnology. Review. Plant regeneration in eggplant (Solanum melongena L.): A review. M. K. Sidhu1*, A. S. Dhatt1 and G. S. Sidhu2 ... economically important genes for the improvement of eggplant. Key words: Callus, somatic embryogenesis, ...

  3. Shoot regeneration and micropropagation of Panax vietnamensis ...

    African Journals Online (AJOL)

    The methods for leaf-derived callus induction, callus proliferation, adventitious shoot induction and plant regeneration of Vietnamese ginseng (Panax vietnamensis Ha et Grushv.) were examined. In this study, callus induction was formed on both medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) alone or in ...

  4. Calcium phosphate coatings for bone regeneration

    NARCIS (Netherlands)

    Yang, Liang

    2010-01-01

    As a novel approach to repair and regenerate damaged and degraded bone tissue, tissue engineering has recorded tremendous growth for the last thirty years. This is an emerging interdisciplinary field applying the principles of biology and engineering to the development of viable substitutes that

  5. Advances in fertilization for hardwood regeneration

    Science.gov (United States)

    Douglass F. Jacobs

    2013-01-01

    Optimizing fertilization programs in the nursery and field may help improve regeneration and restoration of temperate deciduous hardwoods. Our research program has demonstrated the applicability of nutrient loading in fine hardwood systems to promote seedling uptake and storage of nutrients during the nursery phase. We also have shown the benefits of nutrient loading...

  6. Somatic embryogenesis and plant regeneration of recalcitrant ...

    African Journals Online (AJOL)

    Many restrictive factors still remain in cotton tissue culture such as long duration, unpredictability and a high degree of genotype dependence. The main objective of this study was to develop a protocol allowing consistent somatic embryogenesis and plant regeneration from five recalcitrant cotton cultivars. Our results ...

  7. Oak Regeneration Guidelines for the Central Appalachians

    Science.gov (United States)

    Kim C. Steiner; James C. Finley; Peter J. Gould; Songlin Fei; Marc McDill

    2008-01-01

    This article presents the first explicit guidelines for regenerating oaks in the central Appalachians. The objectives of this paper are (1) to describe the research foundation on which the guidelines are based and (2) to provide users with the instructions, data collection forms, supplementary tables, and decision charts needed to apply the guidelines in the field. The...

  8. Enhancement of liver regeneration and liver surgery

    NARCIS (Netherlands)

    Olthof, P.B.

    2017-01-01

    Liver regeneration allows surgical resection of up to 75% of the liver and enables curative treatment potential for patients with primary or secondary hepatic malignancies. Liver surgery is associated with substantial risks, reflected by considerable morbidity and mortality rates. Optimization of

  9. Establishment of high effective regeneration and propagation ...

    African Journals Online (AJOL)

    Jane

    2011-07-11

    , 25(3):293-297. Pindel A, Miczynski K (1996). Regeneration of Cymbidium orchidsfrom leaf and root explants. Floria Horticult., 8(2):95-105. Szankowski I, Briviba K, Fleschhut J, Schönherr J, Jacobsen HJ,. Kiesecker H (2003).

  10. Animal Regeneration: From Fact to Concept.

    Science.gov (United States)

    Dinsmore, Charles E.

    1995-01-01

    Examines the history of the transformation of animal regeneration research from observations to hypothesis-based concepts as a classic example of a view of science as a human endeavor, where social context influences the nature of the science undertaken and the science in turn alters the social context. (LZ)

  11. Reparative inflammation takes charge of tissue regeneration

    NARCIS (Netherlands)

    Karin, Michael; Clevers, Hans

    2016-01-01

    Inflammation underlies many chronic and degenerative diseases, but it also mitigates infections, clears damaged cells and initiates tissue repair. Many of the mechanisms that link inflammation to damage repair and regeneration in mammals are conserved in lower organisms, indicating that it is an

  12. Bone regeneration: current concepts and future directions

    Directory of Open Access Journals (Sweden)

    McGonagle Dennis

    2011-05-01

    Full Text Available Abstract Bone regeneration is a complex, well-orchestrated physiological process of bone formation, which can be seen during normal fracture healing, and is involved in continuous remodelling throughout adult life. However, there are complex clinical conditions in which bone regeneration is required in large quantity, such as for skeletal reconstruction of large bone defects created by trauma, infection, tumour resection and skeletal abnormalities, or cases in which the regenerative process is compromised, including avascular necrosis, atrophic non-unions and osteoporosis. Currently, there is a plethora of different strategies to augment the impaired or 'insufficient' bone-regeneration process, including the 'gold standard' autologous bone graft, free fibula vascularised graft, allograft implantation, and use of growth factors, osteoconductive scaffolds, osteoprogenitor cells and distraction osteogenesis. Improved 'local' strategies in terms of tissue engineering and gene therapy, or even 'systemic' enhancement of bone repair, are under intense investigation, in an effort to overcome the limitations of the current methods, to produce bone-graft substitutes with biomechanical properties that are as identical to normal bone as possible, to accelerate the overall regeneration process, or even to address systemic conditions, such as skeletal disorders and osteoporosis.

  13. Stem cells to regenerate the newborn brain

    NARCIS (Netherlands)

    van Velthoven, C.T.J.

    2011-01-01

    Perinatal hypoxia-ischemia (HI) is a frequent cause of perinatal morbidity and mortality with limited therapeutic options. In this thesis we investigate whether mesenchymal stem cells (MSC) regenerate the neonatal brain after HI injury. We show that transplantation of MSC after neonatal brain injury

  14. Possible functional scaffolds for periodontal regeneration

    Directory of Open Access Journals (Sweden)

    Hidetoshi Shimauchi

    2013-11-01

    Full Text Available Periodontal diseases are the most prevalent infectious diseases with the irreversible loss of tooth supporting apparatus. To reestablish the stable health of periodontal tissues after healing, the concept of regenerative surgical procedures has been developed over the past three decades, including various grafting materials, guided tissue regeneration (GTR, and the use of enamel matrix derivatives (EMD in a clinical setting. More recently, tissue engineering strategies have also been applied and developed for periodontal regeneration: (1 stem cell therapies; (2 recombinant human growth factor therapies; (3 combined use of cell and growth factors with matrix-based scaffolds. However, the complete and predictable reconstruction of healthy periodontal tissues still remains a challenging field. To overcome therapeutic limitations and develop stem cell-based strategies, it is necessary to optimize cell–scaffold combinations by understanding the cellular events during periodontal wound healing and regeneration. We reviewed: (1 the current status and strategies for periodontal regeneration; (2 a possible biomaterial design for the scaffold used in periodontal tissue engineering; (3 a possible interaction between scaffold materials and periodontal tissue cells.

  15. Adventitious shoots induction and plant regeneration from ...

    African Journals Online (AJOL)

    Aghomotsegin

    2015-07-08

    Jul 8, 2015 ... cultivars were placed on MB5 media supplemented with different concentrations and combinations of growth regulators (1.0 ... Key words: Watermelon (Citrullus lanatus), cotyledon, growth regulator, kanamycin, regeneration. ..... expression of Saccharomyces cerevisiae HAL1 gene increases salt tolerance ...

  16. Plant regeneration through indirect organogenesis of chestnut ...

    African Journals Online (AJOL)

    Mehrcedeh

    2013-12-18

    Dec 18, 2013 ... The highest shoot multiplication (66.9%) was observed on. MS medium with 0.2 mgLˉ¹ TDZ. Regenerated shoots were rooted in vitro on MS containing 1.5 mgLˉ¹. IBA. Also, plantlets with well developed root and shoot systems were acclimatized inside the green house and 80% of the plantlets survived ...

  17. The histological study of osseous regeneration following ...

    African Journals Online (AJOL)

    2015-10-28

    Oct 28, 2015 ... Background: While various biomaterials are used for bone regeneration, the relative comparative efficiency of them has not been thoroughly investigated. Purpose: This study evaluated histopathological events during osseous healing after implantation of following bone grafts: Demineralized freeze-dried ...

  18. Is pulp regeneration necessary for root maturation?

    Science.gov (United States)

    Nosrat, Ali; Li, Kevin L; Vir, Kunwar; Hicks, M Lamar; Fouad, Ashraf F

    2013-10-01

    True regeneration of the dental pulp-dentin complex in immature teeth with necrotic pulps has not been shown histologically. It is not known to what extent this true tissue regeneration is necessary to achieve clinically acceptable outcomes. This case report describes the treatment of a patient with an immature maxillary right central incisor with a history of impact trauma and enamel-dentin crown fracture. A diagnosis of pulp necrosis with acute apical abscess was established. A regenerative endodontic protocol that used a paste containing Augmentin for 5 weeks as an intracanal medicament was used. Follow-ups at 9, 12, 17, and 31 months revealed complete osseous healing of the periapical lesion and formation of the root apex, but without increase in root length. Clinically, the tooth was functional, asymptomatic, and nonresponsive to pulp vitality tests. The crown discolored over time. On reentering the root canal, no tissues were observed under magnification inside the root canal space. The root canal treatment was completed with mineral trioxide aggregate obturation. Augmentin might be an acceptable choice for root canal disinfection in regenerative endodontic procedures. The protocol for regenerative endodontic treatment is not predictable for pulp-dentin regeneration. Formation of the root apex is possible without pulp regeneration. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. ADAPTATION OF REGENERANTS OF Vaccinium Corymbosum L

    African Journals Online (AJOL)

    Kutas

    2011-05-09

    May 9, 2011 ... increase the turgor of regenerants to its maximum value. It is achieved by plunging the material into a retort containing distillated water for 5 to 6 h. The second essential condition is to keep high humidity rate in the greenhouse (not under 90%) and remove strong air flows, that is, elimination of any wind ...

  20. Factors that influence peripheral nerve regeneration

    DEFF Research Database (Denmark)

    Krarup, Christian; Archibald, Simon J; Madison, Roger D

    2002-01-01

    Regeneration in the peripheral nervous system is often incomplete though it is uncertain which factors, such as the type and extent of the injury or the method or timing of repair, determine the degree of functional recovery. Serial electrophysiological techniques were used to follow recovery from...

  1. The histological study of osseous regeneration following ...

    African Journals Online (AJOL)

    Background: While various biomaterials are used for bone regeneration, the relative comparative efficiency of them has not been thoroughly investigated. Purpose: This study evaluated histopathological events during osseous healing after implantation of following bone grafts: Demineralized freeze‑dried cortical bone ...

  2. Entrepreneurship Education: Ireland's Solution to Economic Regeneration?

    Science.gov (United States)

    O'Connor, John; Fenton, Mary; Barry, Almar

    2012-01-01

    The significance of entrepreneurship has come into sharper focus as enterprise and innovation are being flagged as solutions to regenerate the Irish economy. The Irish Innovation Task Force believes that Ireland could become an "innovation hub", attracting foreign risk capital and international and indigenous entrepreneurs to start and…

  3. Shoot regeneration and micropropagation of Panax vietnamensis ...

    African Journals Online (AJOL)

    ajl yemi

    2011-12-26

    Dec 26, 2011 ... Tay Nguyen Institute of Biology, 116 Xo Viet Nghe Tinh, Dalat, Lam Dong, Vietnam. Accepted 23 November, 2011. The methods for leaf-derived callus induction, callus proliferation, adventitious shoot induction and plant regeneration of Vietnamese ginseng (Panax vietnamensis Ha et Grushv.) ...

  4. Economic analysis of replacement regeneration and coppice regeneration in eucalyptus stands under risk conditions

    Directory of Open Access Journals (Sweden)

    Isabel Carolina de Lima Guedes

    2011-09-01

    Full Text Available Projects are by their very nature subject to conditions of uncertainty that obstruct the decision-making process. Uncertainties involving forestry projects are even greater, as they are combined with time of return on capital invested, being medium to long term. For successful forest planning, it is necessary to quantify uncertainties by converting them into risks. The decision on whether to adopt replacement regeneration or coppice regeneration in a forest stand is influenced by several factors, which include land availability for new forest crops, changes in project end use, oscillations in demand and technological advancement. This study analyzed the economic feasibility of replacement regeneration and coppice regeneration of eucalyptus stands, under deterministic and under risk conditions. Information was gathered about costs and revenues for charcoal production in order to structure the cash flow used in the economic analysis, adopting the Net Present Value method (VPL. Risk assessment was based on simulations running the Monte Carlo method. Results led to the following conclusions: replacement regeneration is economically viable, even if the future stand has the same productivity as the original stand; coppice regeneration is an economically viable option even if productivity is a mere 70% of the original stand (high-tree planted stand, the best risk-return ratio option is restocking the stand (replacement regeneration by one that is 20% more productive; the probabilistic analysis running the Monte Carlo method revealed that invariably there is economic viability for the various replacement and coppice regeneration options being studied, minimizing uncertainties and consequently increasing confidence in decision-making.

  5. A numerical analysis of a reciprocating Active Magnetic Regenerator with a parallel-plate regenerator geometry

    DEFF Research Database (Denmark)

    Petersen, Thomas Frank; Pryds, Nini; Smith, Anders

    2007-01-01

    We have developed a two-dimensional model of a reciprocating Active Magnetic Regenerator(AMR) with a regenerator made of parallel plates arranged in a stack configuration. The time dependent,two-dimensional model solves the Navier-Stokes equations for the heat transfer fluid and the coupled heat...... choices and operating parameters are presented and the implications for optimal AMR operation are discussed....

  6. Lizard tail skeletal regeneration combines aspects of fracture healing and blastema-based regeneration

    Science.gov (United States)

    Tuan, Rocky S.

    2016-01-01

    Lizards are amniotes with the remarkable ability to regenerate amputated tails. The early regenerated lizard tail forms a blastema, and the regenerated skeleton consists of a cartilage tube (CT) surrounding the regenerated spinal cord. The proximal, but not distal, CT undergoes hypertrophy and ossifies. We hypothesized that differences in cell sources and signaling account for divergent cartilage development between proximal and distal CT regions. Exogenous spinal cord implants induced ectopic CT formation in lizard (Anolis carolinensis) blastemas. Regenerated spinal cords expressed Shh, and cyclopamine inhibited CT induction. Blastemas containing vertebrae with intact spinal cords formed CTs with proximal hypertrophic regions and distal non-hypertrophic regions, whereas removal of spinal cords resulted in formation of proximal CT areas only. In fate-mapping studies, FITC-labeled vertebra periosteal cells were detected in proximal, but not distal, CT areas. Conversely, FITC-labeled blastema cells were restricted to distal CT regions. Proximal cartilage formation was inhibited by removal of periosteum and could be recapitulated in vitro by periosteal cells treated with Ihh and BMP-2. These findings suggest that proximal CTs are directly derived from vertebra periosteal cells in response to BMP and Ihh signaling, whereas distal CTs form from blastema cells in response to Shh signals from regenerated spinal cords. PMID:27387871

  7. Circulating Extracellular RNA Markers of Liver Regeneration.

    Directory of Open Access Journals (Sweden)

    Irene K Yan

    Full Text Available Although a key determinant of hepatic recovery after injury is active liver regeneration, the ability to detect ongoing regeneration is lacking. The restoration of liver mass after hepatectomy involves systemic changes with coordinated changes in gene expression guiding regenerative responses, activation of progenitor cells, and proliferation of quiescent hepatocytes. We postulated that these responses involve intercellular communication involving extracellular RNA and that these could represent biomarkers of active regenerative responses.RNA sequencing was performed to identify temporal changes in serum extracellular non-coding RNA after partial hepatectomy in C57BL/6 male mice. Tissue expression of selected RNA was performed by microarray analysis and validated using qRT-PCR. Digital PCR was used to detect and quantify serum expression of selected RNA.A peak increase in extracellular RNA content occurred six hours after hepatectomy. RNA sequencing identified alterations in several small non-coding RNA including known and novel microRNAs, snoRNAs, tRNA, antisense and repeat elements after partial hepatectomy. Combinatorial effects and network analyses identified signal regulation, protein complex assembly, and signal transduction as the most common biological processes targeted by miRNA that altered. miR-1A and miR-181 were most significantly altered microRNA in both serum and in hepatic tissues, and their presence in serum was quantitated using digital PCR.Extracellular RNA selectively enriched during acute regeneration can be detected within serum and represent biomarkers of ongoing liver regeneration in mice. The ability to detect ongoing active regeneration would improve the assessment of hepatic recovery from liver injury.

  8. Representing Evolution

    DEFF Research Database (Denmark)

    Hedin, Gry

    2012-01-01

    . This article discusses Willumsen's etching in the context of evolutionary theory, arguing that Willumsen is a rare example of an artist who not only let the theory of evolution fuel his artistic imagination, but also concerned himself with a core issue of the theory, namely to what extent it could be applied...

  9. Accepting evolution.

    Science.gov (United States)

    Chinsamy, Anusuya; Plagányi, Eva

    2008-01-01

    Poor public perceptions and understanding of evolution are not unique to the developed and more industrialized nations of the world. International resistance to the science of evolutionary biology appears to be driven by both proponents of intelligent design and perceived incompatibilities between evolution and a diversity of religious faiths. We assessed the success of a first-year evolution course at the University of Cape Town and discovered no statistically significant change in the views of students before the evolution course and thereafter, for questions that challenged religious ideologies about creation, biodiversity, and intelligent design. Given that students only appreciably changed their views when presented with "facts," we suggest that teaching approaches that focus on providing examples of experimental evolutionary studies, and a strong emphasis on the scientific method of inquiry, are likely to achieve greater success. This study also reiterates the importance of engaging with students' prior conceptions, and makes suggestions for improving an understanding and appreciation of evolutionary biology in countries such as South Africa with an inadequate secondary science education system, and a dire lack of public engagement with issues in science.

  10. Greening Evolution

    African Journals Online (AJOL)

    Administrator

    African Journal of Environmental Science and Technology Vol. ... Greening Evolution. The second week in July marks the occasion of an extraordinary conference entitled "Future Trends in Genetics and. Biotechnology for Safe Environment," sponsored by the ... For example, the information presented in Figure 2 shows.

  11. Diversification and enrichment of clinical biomaterials inspired by Darwinian evolution.

    Science.gov (United States)

    Green, D W; Watson, G S; Watson, J A; Lee, D-J; Lee, J-M; Jung, H-S

    2016-09-15

    Regenerative medicine and biomaterials design are driven by biomimicry. There is the essential requirement to emulate human cell, tissue, organ and physiological complexity to ensure long-lasting clinical success. Biomimicry projects for biomaterials innovation can be re-invigorated with evolutionary insights and perspectives, since Darwinian evolution is the original dynamic process for biological organisation and complexity. Many existing human inspired regenerative biomaterials (defined as a nature generated, nature derived and nature mimicking structure, produced within a biological system, which can deputise for, or replace human tissues for which it closely matches) are without important elements of biological complexity such as, hierarchy and autonomous actions. It is possible to engineer these essential elements into clinical biomaterials via bioinspired implementation of concepts, processes and mechanisms played out during Darwinian evolution; mechanisms such as, directed, computational, accelerated evolutions and artificial selection contrived in the laboratory. These dynamos for innovation can be used during biomaterials fabrication, but also to choose optimal designs in the regeneration process. Further evolutionary information can help at the design stage; gleaned from the historical evolution of material adaptations compared across phylogenies to changes in their environment and habitats. Taken together, harnessing evolutionary mechanisms and evolutionary pathways, leading to ideal adaptations, will eventually provide a new class of Darwinian and evolutionary biomaterials. This will provide bioengineers with a more diversified and more efficient innovation tool for biomaterial design, synthesis and function than currently achieved with synthetic materials chemistry programmes and rational based materials design approach, which require reasoned logic. It will also inject further creativity, diversity and richness into the biomedical technologies that

  12. Cell fate determination during tooth development and regeneration.

    Science.gov (United States)

    Mitsiadis, Thimios A; Graf, Daniel

    2009-09-01

    Teeth arise from sequential and reciprocal interactions between the oral epithelium and the underlying cranial neural crest-derived mesenchyme. Their formation involves a precisely orchestrated series of molecular and morphogenetic events, and gives us the opportunity to discover and understand the nature of the signals that direct cell fates and patterning. For that reason, it is important to elucidate how signaling factors work together in a defined number of cells to generate the diverse and precise patterned structures of the mature functional teeth. Over the last decade, substantial research efforts have been directed toward elucidating the molecular mechanisms that control cell fate decisions during tooth development. These efforts have contributed toward the increased knowledge on dental stem cells, and observation of the molecular similarities that exist between tooth development and regeneration.

  13. Stem cell-based biological tooth repair and regeneration.

    Science.gov (United States)

    Volponi, Ana Angelova; Pang, Yvonne; Sharpe, Paul T

    2010-12-01

    Teeth exhibit limited repair in response to damage, and dental pulp stem cells probably provide a source of cells to replace those damaged and to facilitate repair. Stem cells in other parts of the tooth, such as the periodontal ligament and growing roots, play more dynamic roles in tooth function and development. Dental stem cells can be obtained with ease, making them an attractive source of autologous stem cells for use in restoring vital pulp tissue removed because of infection, in regeneration of periodontal ligament lost in periodontal disease, and for generation of complete or partial tooth structures to form biological implants. As dental stem cells share properties with mesenchymal stem cells, there is also considerable interest in their wider potential to treat disorders involving mesenchymal (or indeed non-mesenchymal) cell derivatives, such as in Parkinson's disease. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. In vitro regeneration of kidney from pluripotent stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Osafune, Kenji, E-mail: osafu@cira.kyoto-u.ac.jp [Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); JST Yamanaka iPS Cell Special Project, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2010-10-01

    Although renal transplantation has proved a successful treatment for the patients with end-stage renal failure, the therapy is hampered by the problem of serious shortage of donor organs. Regenerative medicine using stem cells, including cell transplantation therapy, needs to be developed to solve the problem. We previously identified the multipotent progenitor cells in the embryonic mouse kidney that can give rise to several kinds of epithelial cells found in adult kidney, such as glomerular podocytes and renal tubular epithelia. Establishing the method to generate the progenitors from human pluripotent stem cells that have the capacity to indefinitely proliferate in vitro is required for the development of kidney regeneration strategy. We review the current status of the research on the differentiation of pluripotent stem cells into renal lineages and describe cues to promote this research field.

  15. Coal-fired generation

    CERN Document Server

    Breeze, Paul

    2015-01-01

    Coal-Fired Generation is a concise, up-to-date and readable guide providing an introduction to this traditional power generation technology. It includes detailed descriptions of coal fired generation systems, demystifies the coal fired technology functions in practice as well as exploring the economic and environmental risk factors. Engineers, managers, policymakers and those involved in planning and delivering energy resources will find this reference a valuable guide, to help establish a reliable power supply address social and economic objectives. Focuses on the evolution of the traditio

  16. Mammalian Cochlear Hair Cell Regeneration and Ribbon Synapse Reformation

    Directory of Open Access Journals (Sweden)

    Xiaoling Lu

    2016-01-01

    Full Text Available Hair cells (HCs are the sensory preceptor cells in the inner ear, which play an important role in hearing and balance. The HCs of organ of Corti are susceptible to noise, ototoxic drugs, and infections, thus resulting in permanent hearing loss. Recent approaches of HCs regeneration provide new directions for finding the treatment of sensor neural deafness. To have normal hearing function, the regenerated HCs must be reinnervated by nerve fibers and reform ribbon synapse with the dendrite of spiral ganglion neuron through nerve regeneration. In this review, we discuss the research progress in HC regeneration, the synaptic plasticity, and the reinnervation of new regenerated HCs in mammalian inner ear.

  17. Simulated big sagebrush regeneration supports predicted changes at the trailing and leading edges of distribution shifts

    Science.gov (United States)

    Schlaepfer, Daniel R.; Taylor, Kyle A.; Pennington, Victoria E.; Nelson, Kellen N.; Martin, Trace E.; Rottler, Caitlin M.; Lauenroth, William K.; Bradford, John B.

    2015-01-01

    Many semi-arid plant communities in western North America are dominated by big sagebrush. These ecosystems are being reduced in extent and quality due to economic development, invasive species, and climate change. These pervasive modifications have generated concern about the long-term viability of sagebrush habitat and sagebrush-obligate wildlife species (notably greater sage-grouse), highlighting the need for better understanding of the future big sagebrush distribution, particularly at the species' range margins. These leading and trailing edges of potential climate-driven sagebrush distribution shifts are likely to be areas most sensitive to climate change. We used a process-based regeneration model for big sagebrush, which simulates potential germination and seedling survival in response to climatic and edaphic conditions and tested expectations about current and future regeneration responses at trailing and leading edges that were previously identified using traditional species distribution models. Our results confirmed expectations of increased probability of regeneration at the leading edge and decreased probability of regeneration at the trailing edge below current levels. Our simulations indicated that soil water dynamics at the leading edge became more similar to the typical seasonal ecohydrological conditions observed within the current range of big sagebrush ecosystems. At the trailing edge, an increased winter and spring dryness represented a departure from conditions typically supportive of big sagebrush. Our results highlighted that minimum and maximum daily temperatures as well as soil water recharge and summer dry periods are important constraints for big sagebrush regeneration. Overall, our results confirmed previous predictions, i.e., we see consistent changes in areas identified as trailing and leading edges; however, we also identified potential local refugia within the trailing edge, mostly at sites at higher elevation. Decreasing

  18. Regeneration of limb joints in the axolotl (Ambystoma mexicanum.

    Directory of Open Access Journals (Sweden)

    Jangwoo Lee

    Full Text Available In spite of numerous investigations of regenerating salamander limbs, little attention has been paid to the details of how joints are reformed. An understanding of the process and mechanisms of joint regeneration in this model system for tetrapod limb regeneration would provide insights into developing novel therapies for inducing joint regeneration in humans. To this end, we have used the axolotl (Mexican Salamander model of limb regeneration to describe the morphology and the expression patterns of marker genes during joint regeneration in response to limb amputation. These data are consistent with the hypothesis that the mechanisms of joint formation whether it be development or regeneration are conserved. We also have determined that defects in the epiphyseal region of both forelimbs and hind limbs in the axolotl are regenerated only when the defect is small. As is the case with defects in the diaphysis, there is a critical size above which the endogenous regenerative response is not sufficient to regenerate the joint. This non-regenerative response in an animal that has the ability to regenerate perfectly provides the opportunity to screen for the signaling pathways to induce regeneration of articular cartilage and joints.

  19. Regeneration of Limb Joints in the Axolotl (Ambystoma mexicanum)

    Science.gov (United States)

    Lee, Jangwoo; Gardiner, David M.

    2012-01-01

    In spite of numerous investigations of regenerating salamander limbs, little attention has been paid to the details of how joints are reformed. An understanding of the process and mechanisms of joint regeneration in this model system for tetrapod limb regeneration would provide insights into developing novel therapies for inducing joint regeneration in humans. To this end, we have used the axolotl (Mexican Salamander) model of limb regeneration to describe the morphology and the expression patterns of marker genes during joint regeneration in response to limb amputation. These data are consistent with the hypothesis that the mechanisms of joint formation whether it be development or regeneration are conserved. We also have determined that defects in the epiphyseal region of both forelimbs and hind limbs in the axolotl are regenerated only when the defect is small. As is the case with defects in the diaphysis, there is a critical size above which the endogenous regenerative response is not sufficient to regenerate the joint. This non-regenerative response in an animal that has the ability to regenerate perfectly provides the opportunity to screen for the signaling pathways to induce regeneration of articular cartilage and joints. PMID:23185640

  20. Perkembangan Terkini Membran Guided Tissue Regeneration/Guided Bone Regeneration sebagai Terapi Regenerasi Jaringan Periodontal

    Directory of Open Access Journals (Sweden)

    Cindy Cahaya

    2015-06-01

    kombinasi prosedur-prosedur di atas, termasuk prosedur bedah restoratif yang berhubungan dengan rehabilitasi oral dengan penempatan dental implan. Pada tingkat selular, regenerasi periodontal adalah proses kompleks yang membutuhkan proliferasi yang terorganisasi, differensiasi dan pengembangan berbagai tipe sel untuk membentuk perlekatan periodontal. Rasionalisasi penggunaan guided tissue regeneration sebagai membran pembatas adalah menahan epitel dan gingiva jaringan pendukung, sebagai barrier membrane mempertahankan ruang dan gigi serta menstabilkan bekuan darah. Pada makalah ini akan dibahas sekilas mengenai 1. Proses penyembuhan terapi periodontal meliputi regenerasi, repair ataupun pembentukan perlekatan baru. 2. Periodontal spesific tissue engineering. 3. Berbagai jenis membran/guided tissue regeneration yang beredar di pasaran dengan keuntungan dan kerugian sekaligus karakteristik masing-masing membran. 4. Perkembangan membran terbaru sebagai terapi regenerasi penyakit periodontal. Tujuan penulisan untuk memberi gambaran masa depan mengenai terapi regenerasi yang menjanjikan sebagai perkembangan terapi penyakit periodontal.   Latest Development of Guided Tissue Regeneration and Guided Bone Regeneration Membrane as Regenerative Therapy on Periodontal Tissue. Periodontitis is a patological state which influences the integrity of periodontal system that could lead to the destruction of the periodontal tissue and end up with tooth loss. Currently, there are so many researches and efforts to regenerate periodontal tissue, not only to stop the process of the disease but also to reconstruct the periodontal tissue. Periodontal regenerative therapy aims at directing the growth of new bone, cementum and periodontal ligament on the affected teeth. Regenerative procedures consist of soft tissue graft, bone graft, roots biomodification, guided tissue regeneration and combination of the procedures, including restorative surgical procedure that is